Bulletin of the American Physical Society
71st Annual Gaseous Electronics Conference
Volume 63, Number 10
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session LW1: Poster Session II |
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Room: Oregon Convention Center Exhibit Hall A1 |
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LW1.00001: 2D Plasma Current Distribution in an Plasma Etch Tool with Dual-coil ICP Operation Patrick Pribyl, Walter Gekelman, Jia Han, Alex Paterson An industrial plasma etch tool installed at UCLA has been modified for accessibility and research purposes. Plasma is generated using two co-planar stove-top type coils with different radii, positioned above a top ceramic window. The inner antenna operates at 13 MHz and the outer at 2 MHz. A computerized probe drive enables three dimensional magnetic field measurements over the major portion of the interior volume. Local current density is then computed from $\mu_0 \vec J=\nabla \times \vec B$. Local power deposition is inferred from $P=\vec E \cdot \vec J$ with $E$ computed from Faraday's law, or from $P=\eta \vec J \cdot \vec J$, with $\eta$ being consistent with the current diffusion time and profile. Similar volumetric Langmuir probe measurements give $n_e$ and $T_e$. In much of this work profiles are computed from 2D planar measurements assuming azimuthal symmetry, verified against the 3D measurements. Gekelman and Han present extensive results from 2 MHz single-coil operation in adjacent posters at this meeting. This work describes the addition of the second antenna and its resulting modification to the 2 MHz-only profiles. Current distributions from only the 13 MHz, and from combined operation are also presented. [Preview Abstract] |
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LW1.00002: Effect of rf bias frequency on plasma parameters in a remote inductively coupled plasma Zhang Aixian, Lee Moo-Young, Moon Ho-Jun, Chung Chin-Wook The variation of the plasma parameters according to the bias frequency was observed in a remote inductively coupled plasma. A cylindrical Langmuir probe is used to measure the electron energy distribution function (EEDF) and the plasma parameters in this experiment. As the bias power (2 MHz) increases, the plasma density increases linearly and the effective electron temperature decreases inversely at a fixed frequency of main source (13.56 MHz). While applying a bias power having a frequency greater than or similar to the frequency of the main source to the bias electrode results in a trend different from that described previously. The trend of the effective temperature is not significantly affected by the bias power, and the plasma density increases slightly or almost does not change. These changes show that secondary electron emission occurs at the surface of the electrode due to the application of low frequency power. [Preview Abstract] |
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LW1.00003: Effect of RF bias frequency and gas pressure on discharge mode transition in an inductively coupled plasma Howon Lee, Chinwook Chung The discharge mode transition occurs as increasing radio frequency (RF) power in the RF-biased Inductively coupled plasma (ICP) . Plasma density is measured using a Langmuir probe with various gas pressures and frequencies. At fixed ICP power, the plasma density has a maximum value at a certain bias power. Also, as changing the pressure and the bias frequency, the RF bias power that maximizes the plasma density is changed. This can be explained by the mode transition according to the RF bias power. A mode transition occurs when the power dissipation in the ion acceleration mode becomes larger than that in the electron heating mode and the ion acceleration mode is determined by the pressure and the bias frequency. This shows that the plasma density is determined by the balance between the electron heating energy and the ion loss energy. [Preview Abstract] |
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LW1.00004: Experimental and theoretical results on effect of multi-step ionization on total energy loss in an argon inductive discharge Young-Hun Hong, Chin-Wook Chung The change of total energy loss ($\varepsilon_{\mbox{T}} )$ with electron temperature was analyzed by a global model considering multi-step ionization in the argon inductive discharge. As pressure increases, collisional energy loss ($\varepsilon_{\mbox{c}} )$ increases but mean kinetic energy lost per ion lost ($\varepsilon_{\mbox{i}} )$ and mean kinetic energy lost per electron lost ($\varepsilon_{\mbox{e}} )$ decrease. Therefore, there is a pressure that $\varepsilon_{\mbox{T}} $ becomes minimum and its corresponding electron temperature is present. When $\varepsilon_{\mbox{T}} $ is minimized at certain pressure and electron temperature, the plasma is more efficiently generated and the density is maximized. The $\varepsilon _{\mbox{c}} $ considered the multi-step ionization is lower than the unconsidered case. It can be predicted that there will be a minimum value of $\varepsilon_{\mbox{T}} $ at lower electron temperature. In this work, we studied the effect of multi-step ionization on the electron temperature where $\varepsilon_{\mbox{T}} $ is the minimum. For each condition, the electron temperature and the plasma density were measured and the total energy loss $\varepsilon_{\mbox{T}} $ was obtained through these measured values. [Preview Abstract] |
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LW1.00005: Electrical characteristics and plasma parameters during E – H mode transition in an inductively coupled plasma Jun-Hyeon Moon, Ho-Jun Moon, Chin-Wook Chung The phenomena that the antenna coil current is decreased after the E – H mode transition is investigated in a cylindrical inductively coupled plasma. When the E – H mode transition is occurred in certain discharge conditions such as low driving frequency and high pressure, the decrease of antenna coil current and voltage are observed. This phenomenon has explained by negative differential impedance. For this phenomenon to be possible, the slope of absorbed power to the plasma must be lower than the slope of transferred power. In this work, the calculation of transferred power and absorbed power is used to explain the decrease of antenna coil current. The density jump after E – H mode transition is also explained by the transferred power and dissipated power. [Preview Abstract] |
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LW1.00006: Nonlinear circuit analysis of intermodulation currents via plasma sheath in a floating Langmuir probe Kyung-Hyun Kim, Moo-Young Lee, Chin-Wook Chung When dual frequency $\omega_{1} ,\mbox{\thinspace }\omega_{2} $voltage having small amplitude are biased to a floating Langmuir probe, intermodulation currents $i_{\omega_{2} \pm \omega_{1} } ,\mbox{\thinspace }i_{\omega_{2} \pm 2\omega_{1} } $are generated due to nonlinearity of sheath near the probe. From the intermodulation currents, electron temperatures and plasma densities can be obtained. If the probe has a capacitive load such as contaminated tip of the probe, harmonic and intermodulation voltages of the probe bias are applied to the sheath. The currents are split into several harmonic currents through harmonic balance technique that analyzes nonlinear circuit. The sum of the harmonic currents was compared with the measured intermodulation current. Electron temperature and plasma density obtained from the currents were compared to that of a single Langmuir probe. [Preview Abstract] |
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LW1.00007: Effect of step ionizations on the high energy electron temperature in an argon inductively coupled plasma. Park Geun-Hong, Kim Kyung-Hyun, Chung Chin-Wook The effect of step ionizations on the high energy electron temperature was studied in an argon inductive discharge. The electron energy distribution function (EEDF) was measured by using Langmuir probe at various powers and pressures. The optical emission spectrum was also measured to obtain metastable densities. We observed the change of high energy electron temperature as increasing absorbed power. This can be explained that the contribution of multi-step ionizations increases with the electron density and pressure. The high metastable densities tend to be more affected the variation of the high energy electron temperature. As a result, the high metastable densities enhance the multi-step ionizations and therefore the high energy electron temperature increases. [Preview Abstract] |
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LW1.00008: Electrical diagnostic method on electron temperature and ion density using the self-bias effect of square waveform voltage in a Langmuir probe Hyundong Eo, Moo-Young Lee, Kyung-Hyun Kim, Chin-Wook Chung A method for measuring the electron temperature and ion density of a plasma using a dc self-bias effect generated by biasing two square voltages to a Langmuir probe is proposed. By sequentially applying square voltages with two amplitudes to the probe, each dc self-bias voltage is measured. Electron temperature can be obtained from the difference of the self-bias. The amplitude of the fundamental frequency with respect to the square voltage is obtained by Fourier transform. Ion density is obtained using the amplitude and the electron temperature. The measured electron temperature and ion density via our method are compared and good in agreement with the results of EEPF at various discharge conditions. [Preview Abstract] |
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LW1.00009: Effect of non-uniform magnetic field on antenna-plasma coupling efficiency in a low magnetic field helicon discharge. Sonu Yadav, Kshitish Kumar Barada, Prabak Kumar Chattopadhyay The ionization efficiency of helicon plasma discharge is explored by changing the low axial magnetic field gradients near the helicon antenna. The highest plasma density is found for most possible diverging field near the antenna by keeping the other operating parameters unchanged. Measurement of axial wave number together with estimated radial wave number suggests the oblique mode propagation of helicon wave along the resonance cone boundary. Propagation of helicon wave near the resonance cone angle boundary can excite electrostatic fluctuations which subsequently can deposit energy in the plasma. This process has been shown to be responsible for peaking in density in low field helicon discharges, where the helicon wave propagates at an angle with respect to the applied uniform magnetic field. The increased efficiency can be explained on the basis of multiple resonances for multimode excitation by the helicon antenna due to the availability of a broad range of magnetic field values in the near field of the antenna when a diverging magnetic field is applied in the source. [Preview Abstract] |
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LW1.00010: Magnetic Configuration of Magnet-embedded Lisitano Antenna and Sputter Source for High Current Metal Ions Generation Oleksii Girka, Hyun Jong You The magnetic drift of the fast electrons, due to the gradient and curvature of the magnetic field, plays an important role in the efficiency of the ECR plasma production in the multipolar magnetic field structure [1]. The objective of present research is to find the optimum magnetic configuration of the Magnet-embedded Lisitano antenna (MeLA) [2,3] and sputter source. The combination of the MeLA and sputter source is used for the high-density plasma production and successive high-current ion beam generation. The magnetic field gradient and curvature for the trapping higher density of the fast electrons are investigated via 3D magneto-static modelling of the MeLA and planar sputter. The results of 3-axis magnetic probe measurements are in good agreement with the results of magneto-static modeling. The ECR plasma parameters are also measured for Ar and Cu plasmas. The optimized magnetic configuration based on 3D magneto-static modelling and experimental plasma characterization is discussed. [1] T. Lagarde et al. Pl. Sources Sci. Technol. 6, 53 (1997); [2] G. Lisitano et al. Rev. Sci. Instr. 39, 295 (1968); [3] H.J. You et al. US8648534B2, KR10-1791350. [Preview Abstract] |
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LW1.00011: Tomographic reconstruction of the azimuthal current distribution in a HiPIMS discharge Kevin Koehn, Dennis Krueger, Ralf Peter Brinkmann High power impulse magnetron sputtering (HiPIMS) is a novel physical vapor deposition technique capable of depositing thin films with superior properties. A characteristic feature of this magnetron based discharge is a torus of plasma embedded inside the external poloidal magnetic field. This azimuthal current distribution is primarily driven by a combination of guiding center drifts and a contribution which stems from a pressure gradient. The current distribution can in principle be obtained from measurements of the induced radial and axial magnetic field. A first approach is based on the solution of Ampere's law, however, it is limited to the area where magnetic field measurements are available. Particularly, the region in close vicinity to the target where most of the azimuthal current is expected, is excluded. In this work, we investigate alternative approaches to determine the current density. The plasma torus is modeled by $N$ ring currents scanning the whole domain. The total magnetic field generated by the superposition of all current contributions is fitted to the experimental data. Different regression methods like linear regression, ridge regression and an approach based on Bayes' theorem are implemented and compared against each other. [Preview Abstract] |
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LW1.00012: Effect of the magnetic field on rotating spoke in ExB discharge Eduardo Rodriguez, Yevgeny Raitses, Andrew Powis, Igor Kaganovich, Andrei Smolyakov The internal structure and behavior of self-organised quasi-periodic m$=$1 mode disturbances (so called rotating spokes) in low pressure ExB discharges is studied, and the effect that the magnetic field has on it is experimentally pursued. Both the influence of the field magnitude and topology are explored in an ExB Penning discharge [1], with particular emphasis on fringing/divergent B fields.~ The assessment of cross-field anomalous transport in the plasma is a primary focus of this research.~For example, probe measurements of plasma density and plasma potential variations demonstrate that the electron cross-field current due to these fluctuations is nearly 90{\%} of the total discharge current. Changes of the magnetic field topology can lead to a significant reduction of the spoke with quieter oscillations, partially consistent with our suppression predictions from Particle-in-Cell Simulations. [1] J. Carlsson, et al., Phys. Plasmas 25, 061201 (2018) [Preview Abstract] |
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LW1.00013: Fluid modeling and linear analysis of instabilities in ExB discharge plasmas in Hall Thrusters Sarah Sadouni, Gerjan Hagelaar, Andrei Smolyakov ExB discharge plasmas, present in devices such as Hall thrusters, show the emergence and growth of instabilities, subject of our study. The LAPLACE laboratory in Toulouse elaborated its own self-consistent fluid code called “MAGNIS”, previously used for the study of transport phenomena occurring in the negative ion source for ITER. This 2D code considers the plane perpendicular to the magnetic field for its simulations, and can describe the ExB plasma configuration. The aim is to compare the instabilities described by MAGNIS to the results of an analytical linear analysis : measured growth rate, frequency and wave numbers compared to those given by elementary dispersion relations characteristic of reference instabilities in literature that are likely to develop in the Hall thruster configuration. Through this analysis we are able to verify the relevance and the numerical capabilities of the MAGNIS code to describe the instabilities in a Hall thruster and better understand their behavior over a wide range of parameters and their effects. [Preview Abstract] |
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LW1.00014: A magnetized plasma apparatus for non-linear microwave interaction experiments K Ronald, D Speirs, A Phelps, B Eliasson, A Cross, C Whyte, C Robertson, R Cairns, M Koepke, R Bingham Following a series of laboratory experiments [1,2] simulating natural plasma instabilities [3], a larger apparatus is being constructed for experiments on nonlinear coupling between microwaves in plasma, relevant to laser-plasma, ionospheric, and magnetically confined fusion plasma environments. Normalized intensities approaching those used in some recent laser plasma interactions can be generated using flexible microwave amplifiers, whilst the relatively accessible plasma relevant to coupling of microwave frequency signals will enable the use of insertion diagnostics in addition to stand-off analysis of the EM signals. The linear plasma experiment will be magnetized at up to 0.08T, an RF helicon source will be used to generate a dense, large, cool plasma with high ionization fraction (n$_{\mathrm{e}}$ up to 10$^{\mathrm{19}}$m$^{\mathrm{-3}}$ has been reported in other helicon experiments). The paper will present the proposed apparatus and outline the envisioned research program. [1] S.L. McConville, et al., Plasma Phys. Control. Fusion, 50, 2008, 074010, [2] K. Ronald, et al., Phys. Plasmas, 15, 2008, 056503, [3] D.C. Speirs, et al., Phys. Rev. Lett., 113, 2014, 155002. [Preview Abstract] |
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LW1.00015: Efficient Switching of a Microwave Pulse Compressor by a Laser Initiated Gas Discharge Yoav Hadas, Jacob Cohen, John Leopold, Yakov Krasik Microwave Pulse Compressor (MPC) is an HPM device designed for generation of 100's of MW's thru amplification. The amplification is based upon time compression of an initial Microwave (RF) pulse characterized by a long (usec) duration to a short (ns) output pulse, ideally increasing the RF power by the duration ratio of the pulses. The MPC utilizes a pressurized RF resonator. Initiating a discharge in the gas, forms in a thin plasma channel sufficient to reduce the Q factor of the resonator, i.e. switch the resonator from a storage phase to a release phase. This switching enables the accumulated RF power to be radiated outside the system. We demonstrate experimentally an efficient way to cause a discharge in the pressurized gas, filling the resonator, by focusing an intense (\textasciitilde 1GW) laser pulse inside the MPC volume. We found that as the accumulated energy inside the resonator increases, the time delay between lasing and switching decreases. We were able to simulate this phenomenon by 2D-Lsp hybrid PIC modeling where we assume that the resonator is pressurized with gas, uniformly distributed background electron density of 103 cm-3 and seed electrons density occupying the laser focal region. Electron impact ionization develops self consistently with the oscillating RF field which eventually creates a plasma channel sufficient for the MPC switching. We fitted the seed electron density and the volume of the focal region to match the experimental results. [Preview Abstract] |
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LW1.00016: Modeling of a large experimental DBD reactor using Ar-HMDSO mixtures at atmospheric pressure M. M. Becker, D. Hegemann, B. Nisol, S. Watson, M. R. Wertheimer, C.-P. Klages, D. Loffhagen Hexamethyldisiloxane (HMDSO) is often used as monomer in dielectric barrier discharges (DBDs) for the deposition of %silicon-organic organosilicon films. Already small admixtures of a few ppm of this monomer to the noble carrier gas lead to drastic changes of the discharge characteristics due to Penning ionization processes. In the present contribution, the impact of HMDSO on the electrical discharge characteristics of a large reactor for performing DBD experiments at atmospheric-pressure is investigated by means of numerical modeling. A time-dependent, spatially one-dimensional fluid model has been used to analyze discharges in argon with monomer admixture in the range from 0 to 600\,ppm applying an a.c.\ voltage with an amplitude of 4\,kV and a frequency of 20\,kHz. First comparison with corresponding experimental data shows quite good agreement between measured and modeling data for the discharge current. [Preview Abstract] |
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LW1.00017: Measurement of atomic oxygen and estimation of local temperature in narrow gap discharge for ozone generator Yusuke Nakagawa, Takuya Kawakita, Satoshi Uchida, Fumiyoshi Tochikubo Ozone generator is a very popular application of atmospheric pressure plasma. Recent ozone generators improve the ozone yield and density using sub-mm narrow discharge gap. On another front, ozone generation in pure oxygen has 'ozone zero' problem, which is a gradual drop in ozone yield under continuous operation. Although trace additive gas or electrode surface treatment are known technique to prevent ozone zero, the mechanism has not been investigated in detail. The chemical process near the electrode is quite important to understand the ozone zero mechanism. To clarify the ozone generating reaction near the electrode, we measured the density of atomic oxygen using two-photon absorption laser induced fluorescence (TALIF) method in 0.5 mm narrow gap oxygen discharge. The density of atomic oxygen decays within 40 $\mu$s after a discharge pulse, which is supposed to be faster than in air discharge. Besides, the local temperature in discharge region is important to understand the chemical reactions of radicals. The rate coefficients strongly depend on temperature; therefore, we can estimate the temperature by comparing the measured decay of atomic oxygen density with the chemical reaction simulation. The local temperature after the discharge is estimated to be about 480 K. [Preview Abstract] |
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LW1.00018: Study of Single Filament Dielectric Barrier Discharge in Argon Bahram Mahdavipour, Sebastian Dahle, Jens Oberrath Dielectric barrier discharges are devices, which were first invented to generate ozone. Today, they have a lot of applications such as surface modification, plasma-enhanced chemical vapor deposition, excitation of CO$_{\mathrm{2}}$ lasers and excimer lamps, plasma display panels, pollution control, as well as gas and air cleaning. At atmospheric pressure DBDs are typically filamentary, comprising a number of individual breakdown channels (micro discharges) with very short time duration of several nanoseconds. Most of the chemical effects of filamentary DBDs take place in their micro discharges. Due to that, this work focusses on the study of micro discharges at low temperature and atmospheric pressure conditions in argon to investigate its creation process. Therefore, a symmetric needle-to-needle geometry was designed, where both electrodes are covered by dielectric. A 2D simulation in COMSOL Multiphysics is presented to show the characteristics of the micro discharge. The overall discharge behavior can be validated by electrical measurements and optical emission spectroscopy, thus allowing to compare mean electron densities and energies. [Preview Abstract] |
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LW1.00019: The Role of Initial Metastables in Discharge Evolution Matthew Hopkins, Nicholas Roberds, George Nail, Edward Barnat The evolution of a discharge process in a repetitively discharged system of atomic gas can be complicated due to the presence of unknown amounts of metastable neutral atoms. This is due to the lower ionization energies required for a metastable atom than a ground state one. To better understand the change in discharge behavior of such a repetitively discharged system we investigate the role of initial metastable populations in discharge. If there is a sufficient initial metastable population, then the transient behavior of the discharge, and indeed perhaps the existence of a discharge at all, can be strongly influenced. The work presented here aims to demonstrate the effects of different initial metastable populations, and identify the different discharge modalities (e.g., faster initiation) by simulating moderate pressure 1D helium discharges in the Particle-in-Cell Direct Simulation Monte Carlo code, Aleph. The change in Paschen curves due to the presence of different densities of metastable atoms will be explored. Finally, comparisons to experimental results will also be shown. [Preview Abstract] |
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LW1.00020: One-dimensional plasma chemistry model for parallel plate dielectric barrier discharges (DBDs) and conversion to volume averaged model Changho Yi, Sung-Young Yoon, Sangheum Eom, Seungil Park, Seungmin Ryu, Seong Bong Kim The volume averaged plasma chemistry models (0D models) commonly assumed spatially homogeneous Gaussian-like pulsed electric fields (SHGP E-fields) to calculate the transient behaviors of microdischarges and chemistry. Thus discharges were also homogeneous, and their characteristics depended on the E-field only. However, for volume microdischarges such as parallel plate DBDs (PP-DBDs), the discharge characteristics depend on the electrode geometries, e.g. as gap distance, as well as E-fields, and the microdischarges in air generally do not fill entire volume of PP-DBDs for one period. Thus, for PP-DBDs, the characteristics of E-field may need some adjustments to properly reflect the characteristics of microdischarges while keeping the assumption of SHGP E-fields. In this paper, PP-DBDs in humid air were numerically investigated by using the 0D and 1D fluid models, and the characteristics of SHGP E-fields of the 0D model were adjusted. Finally, transient behabiors of plasma chemistries were calculated by using the adjusted 0D model and compared with those of experiments. [Preview Abstract] |
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LW1.00021: Generations and accessibilities of field-emitting surface dielectric barrier discharges in various environments Moriyuki Kanno, Ryo Tanaka, Sven Stauss, Tsuyohito Ito, Kazuo Terashima Discharges are often used for providing charges and charging is applied for separating toxic particles in environments, material analysis, and so on. To avoid high reactivities, discharges without breakdown are sometimes required. When electrons are provided via field emissions, ionizations are not required for sustaining discharge and thus electron energy could be kept low for avoiding high reactivity. Such discharge mode in surface dielectric barrier discharges have been achieved in high-pressure CO$_{\mathrm{2}}$ including supercritical fluids and in silicone oil. The mode was named as field-emitting surface dielectric barrier discharge (FESDBD) [1] and its applicability for charging particles has been demonstrated [2]. In order to verify its generality, we experimentally investigated the possibility of FESDBD generations even in Ar or N$_{\mathrm{2}}$ gases. In addition, we will show that the accessibility to the FESDBD mode depending on the environmental species could be qualitatively expected via a Townsend-based theory. The details will be presented at the conference. [1] D. Z. Pai, \textit{et al.}, \textit{Plasma Sources Sci. Technol.}, \textbf{23} 25019 (2014). [2] T. Kawamura, \textit{et al.}, \textit{J. Appl. Phys.}, \textbf{123 }043301 (2018). [Preview Abstract] |
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LW1.00022: NO generation using surface dielectric barrier discharges with gas heating. Seungil Park, Changho Yi, Sung-Young Yoon, Seungmin Ryu, Seong Bong Kim This paper represents a nitric oxide (NO) generation using surface dielectric barrier discharges (SDBDs) at atmospheric pressure (AP) with gas heating. Nitric oxide is one of the dominant long-lived reactive species generated by the plasma, and is identified to play a key role in sterilization and inhibition of respiration in agricultural products. By adjusting the gas temperature, the plasma chemistry can be changed from an ozone (O$_{\mathrm{3}})$-dominated mode to nitrogen oxides (NO$_{\mathrm{x}})$-dominated mode. The ambient gas was heated using an IR lamp heater installed on the electrode of SDBDs, and clean dry air (CDA) was used to minimized the influence of the humidity at atmospheric pressure. The concept of NO generation using SDBDs with gas heating was verified by measuring the O$_{\mathrm{3}}$ and NO$_{\mathrm{x}}$ concentrations with gas analyzers, and the mode transition due to temperature rise of ambient gas was observed with a constant power at atmospheric pressure. This plasma source is characterized to generate only NO by controlling the gas heating temperature and time interval between heating and plasma discharge. The measured data was compared with the calculated data using global model. [Preview Abstract] |
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LW1.00023: Phase-resolved modelling of a filamentary argon plasma in an RF plasma jet F. Sigeneger, M. M. Becker, J. Sch\"{a}fer, R. Foest, D. Loffhagen A time-dependent, spatially two-dimensional fluid model, combined with a model of the gas flow and heating, is used to describe the RF plasma in a miniaturized non-thermal plasma jet. The jet is configured as a capacitively coupled capillary discharge driven by an RF voltage at a frequency of 27.12\,MHz which is supplied to the upper of both the ring-shaped electrodes attached to the capillary. The lower electrode is grounded. In the active zone between both electrodes, a filamentary plasma is ignited in the argon gas flowing from above through the capillary. In the present contribution, first results of a combined model including the temporal resolution of the RF period and the influence of the gas flow and heating are presented. A curved trajectory representing the filament is obtained which guides the current between the powered and grounded electrodes. Along this path, the electron density reaches values of more than $10^{20}$\,m$^{-3}$. The gas flow leads to density profiles of all species which are shifted in downstream direction. Striations are generated from the upstream side and spread in downstream direction. The phase-resolved evolution of the mean energy shows slight modulations in the bulk and large ones in the sheath regions in front of the electrodes. [Preview Abstract] |
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LW1.00024: Effect of differing electrode metals on reactive species generation in humid N2/O2 atmospheric pressure dielectric barrier discharge plasmas Alex Gemsheim, Shivam Patel, Matthew Goeckner, Lawrence Overzet Atmospheric dielectric barrier discharge (DBD) plasma is rapidly expanding as a research field because of its applications in medical, industrial, and processing technologies. To form a DBD plasma, a strong dielectric is used to separate two metal electrodes. This plasma dissociates the surrounding gas, producing reactive oxygen and nitrogen species (RONS). Two RONS of interest include ozone and nitric acid because of the potential to use them in myriad applications. The RONS concentrations in a particular environment can be time dependent. Here we make use of a GEC Reference Cell to create and maintain a well-controlled environment. The Cell is first evacuated, and then refilled to atmospheric pressure with precise mixtures of N2, O2 and H2O. Using Fourier transform infrared spectroscopy we are able to monitor the time evolution of several RONS created in the Cell. By using differing electrode materials, with all other parameters held constant, we are able to examine the effect of differing metal surfaces on RONS generation. For example, gold electrodes enabled the production of 30{\%} more ozone and 3{\%} more nitric acid than copper electrodes at essentially the same operating conditions and time. [Preview Abstract] |
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LW1.00025: Temporal evolution of electron density in anomalously dense non-equilibrium argon plasma Taemin Yong, Mark Cappelli This study investigates generating a dense non-equilibrium plasma states in high presure (up to 10 bar) Argon. Initially, electric discharges are generated using high voltage nanosecond pulses (10 kV, 20ns) and then a relatively low energy picosecond laser (\textasciitilde 1 mJ) is applied for the further ionization of the initial dischage plasma. The electrode configuration consists of a pin-to-pin geometry with short gap (\textasciitilde 200 um). The temporal evolution of electron density during one cycle (\textasciitilde 100 ns) is measured by optical emission spectroscopy with 10 picosecond-resolution streak camera. The electron density is inferred from the Stark broadening of H \begin{figure}[htbp] \centerline{\includegraphics[width=0.09in,height=0.17in]{150620181.eps}} \label{fig1} \end{figure} line (656.2nm) and Ar I (2p-1s) line (696.5 nm). [Preview Abstract] |
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LW1.00026: Abstract Withdrawn
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LW1.00027: Numerical Characterization of Ar and He/N2 RF Atmospheric Pressure Plasma Discharges Steven Marcinko, Davide Curreli, Sangwon Lee, Se Youn Moon Atmospheric Pressure Plasma Discharges (APPD) are attractive for a number of industrial applications in surface processing due to the absence of vacuum systems found in traditional plasma processes, lowering costs and permitting continuous operation. Helium has traditionally been used in these discharges due to the stability granted by the long-lived metastable of both the singlet and triplet states, and considerable Penning ionization. However, the cost of helium is becoming prohibitive at industrial scales. Argon is cheaper, abundant, and well characterized, but it is comparatively less efficient due to shorter-lived metastable states. In this work, the discharge characteristics of APPD operating with pure argon, helium with trace nitrogen impurities, and helium-nitrogen gas mixtures ranging from 10-20\% N2 are systematically studied under applied RF voltages of amplitude 200-300V and RF frequencies of 13.56 MHz. Resulting data sets are compared to analyze the effect of voltage and gas composition on discharge parameters including spatially-dependent electron densities, temperatures, voltages, and densities of relevant ionized and excited heavy species. Expected surface fluxes of charged particles are computed and used to infer deposition rates of heavy species onto the target. [Preview Abstract] |
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LW1.00028: Electron dynamics in micro atmospheric pressure radio frequency plasma jets Lena Bischoff, Gerrit Huebner, Ihor Korolov, Julian Held, Volker Schulz-von der Gathen, Thomas Mussenbrock, Yue Liu, Peter Hartmann, Zoltan Donko, Julian Schulze Radio frequency driven micro atmospheric pressure plasma jets ($\mu $-APPJ) are often used as efficient sources of reactive species at low temperatures for, e.g. biomedical applications. Reactive species can be generated via electron impact excitation/dissociation of the neutral gas. To understand these processes, we investigate the electron dynamics in a $\mu $-APPJ operated at 13.56 MHz in He/O$_{\mathrm{2}}$/N$_{\mathrm{2}}$ by phase resolved optical emission spectroscopy using different emission lines. The results show that the spatio-temporal excitation dynamics obtained from the plasma emission at different wavelengths are different. This effect is explained by different energy thresholds of the electron impact excitation of the corresponding excited state and generally by the shape of the corresponding cross section. Thus, different parts of the electron energy distribution function are probed by using different emission lines and a careful selection of the emission lines is required to determine the mode of discharge operations. [Preview Abstract] |
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LW1.00029: 2D Particle-In-Cell Simulation for the Effect of ION Enhanced Field Emission on Micro Gap Discharges Chang Ho Kim, Hae June Lee Due to the pioneering study for the analytical model of breakdown curve including field emission effect [1,2], we can approach the phenomena that were not explicitly described by classical Paschen's breakdown theory in a few micrometer regimes. During plasma processing, it is important to figure out if undesirable micro gap discharges occur and develop to a micro-arc, which leads to yield loss by wafer damage, wafer contamination, and tool downtime. A number of studies have been conducted to investigate micro gap discharges, but most of them have been performed experimentally or in a one-dimensional simulation [2]. In this study, we investigate the tendency of the primary parameters of plasma in a simulation domain with a gap size of a few micrometers using a two-dimensional particle-in-cell (PIC) simulation. The effect of ion-enhanced field emission is imposed in the simulation, and the breakdown voltage has been measured and compared with the theory [1] with the variance of the gap distance and the electrode structure. [1] D. B. Go and D. A. Pohlman, J. Appl. Phys. \textbf{107}, 103303 (2010). [2] D. B. Go and A Venkattraman, J. Phys. D: Appl. Phys. \textbf{47}, 503001 (2014). [Preview Abstract] |
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LW1.00030: Numerical simulations of an atmospheric pressure microplasma jet driven by tailored voltage waveforms Yue Liu, Thomas Mussenbrock, Torben Hemke, Ihor Korolov, Julian Schulze Capacitive microplasma jets driven at atmospheric pressure by sinusoidal or particularly tailored voltage waveforms are employed as efficient plasma sources for surface modification and other processes. One special variant is the micro atmospheric pressure plasma jet ($\mu$APPJ). In this contribution the characteristics of the $\mu$APPJ driven by different voltage waveforms in a helium-oxygen mixture are studied by numerical simulations. The density and temperature of the electrons, as well as the concentration of all reactive species are studied in both the region between the electrodes and within the effluent, particularly with regard to the effect of different driving voltage waveforms. [Preview Abstract] |
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LW1.00031: Observation of cross sectional plasma structure in a gap of an atmospheric pressure microwave discharge Hirotaka Toyoda, Yoshiki Baba, Haruka Suzuki Microwave discharge plasma using slot is attractive due to its ability of high-density and stable plasma production, and we have developed a long-scale AP microwave plasma (AP microwave line plasma: AP-MLP) source up to 1 m in length using loop-structured waveguide and travelling wave. So far, we have measured plasma structure from the outside of the waveguide, but cross-sectional observation of the plasma inside the gap has not been observed yet. In this work, we have developed an atmospheric pressure pulsed-microwave plasma source where outer conductor of a coaxial waveguide is cut into two and plasma is produced in the gap. Cross sectional structure of the plasma is observed using a microscope and an ICCD camera. Emission from the plasma showed that the most intense region in the vicinity of the gap electrode and that the emission intensity decays with the distance from the inner side of the waveguide to the outer side. With increasing the gas flow speed, shift of the emission region from the inside to the outside is clearly observed, indicating the importance of the gas flow on the plasma structure. Time-resolved measurement of the emission shows development of the plasma after turning on the microwave power. [Preview Abstract] |
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LW1.00032: Influence of gas heating on atmospheric-pressure dc glow discharge Fumiyoshi Tochikubo, Kenichi Kitano, Yusuke Nakagawa, Satoshi Uchida DC atmospheric-pressure glow discharge (APGD) using noble gas is one of easy methods to obtain a nonequilibrium plasma at atmospheric pressure. It can be applied to glow discharge electrolysis with stable plasma-liquid interface$^{(1)}$. We investigated the structure of DC APGD along helium flow in nitrogen by 2D simulation$^{(2)}$. In that work, the gas flow was calculated first without APGD, and then the APGD was calculated under the calculated local gas composition. In the real DC APGD, Joule heating of gas will strongly influence the discharge structure and the local plasma chemistry. In this work, we carried out the coupled 2D simulation of gas dynamics and DC APGD in nozzle-plate electrode geometry with helium flow from the nozzle in nitrogen. The body force and Joule heating from charged particle motion are considered in the gas dynamics, and the local gas composition and gas temperature are included in the APGD simulation. The body force due to positive ions in cathode fall region accelerated the gas flow. The gas temperature in the positive column exceeds 1000 K, which is confirmed from the rotational temperature of N$_2$ 2nd positive band. (1) F. Tochikubo et al., Jpn. J. Appl. Phys. {\bf 53} (2014) 126201. (2) F. Tochikubo et al., APEX {\bf 4} (2011) 056001. [Preview Abstract] |
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LW1.00033: High Current Arc Modulation with Solid-State Switching Power Supply Kenneth E. Miller, Seth Anderson, Jim Prager, Timothy Ziemba Modulation of high current arcs is important for both research and industrial applications. Eagle Harbor Technologies, Inc. (EHT) has constructed a test system using an EHT Nanosecond Pulser to initiate the discharge and four EHT Integrated Power Modules (IPM) to drive and modulate the current in the arc. The EHT Nanosecond Pulser can produce high voltage pulses up to 20 kV with adjustable pulse width (30 -- 250 ns), and high pulse repetition frequency (10 kHz). The EHT IPM is a solid-state high current switch that can be operated at several megahertz. We will present the circuit diagram, test setup, and waveforms demonstrating current modulation at high frequency (2 MHz). [Preview Abstract] |
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LW1.00034: Formation of Arc Anode Spot as Function of Rotate Magnetic Field and Moving Speed of Welding Torch. Yoshiyuki Zama, Yoshifumi Maeda, Toru Iwao Tungsten inert gas arc welding has useful joining technology because of high-energy and high-current characteristics. However, the welding speed should be slow because of the electrode erosion. If the moving speed of torch increased, the arc stagnates at the anode spot, and the restrike occurs. In this case, the weld defect occurs. Thus, the arc deflection should be prevented with applying the rotate magnetic field. In this research, the formation of arc anode spot as function of the rotate magnetic field and moving speed of welding torch is elucidated. That magnetic flux density and moving speed of the torch were varied from 0 to 3 mT and 300 to 3,000?mm /?min, respectively. The axial plasma gas argon flow rate was varied from 5 to 8?slm. A rotate magnetic field is applied to the arc using Helmholtz coil and Solenoid Coil. The anode is used by a SUS 304. As a result, the arc anode spot increases with increasing the moving speed of welding torch. Thus, it became difficult to form the arc anode spot, and stagnation hardly occurred as function of rotate magnetic field. Therefore, the welding speed can improve. [Preview Abstract] |
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LW1.00035: Rotation Radius of Spiral Arc Affected by Rigidity Decrement in Axial Magnetic Field Yuto Naito, Yoshifumi Maeda, Toru Iwao HVDC (High Voltage Direct Current) used in the case of electric transmission of renewable energy. However, it is difficult to cut off current in HVDC. The method of applying axial magnetic field to the arc is considered. Axial magnetic field is applied to same direction with arc. The arc makes the circular motion in axial magnetic field. This condition arc is called spiral arc. The length of spiral arc is longer than that of steady when the arc becomes spiral, the voltage increases. Thus, it is easy to interrupt the current. The arc length and voltage increase because of rigidity decrement affected by current decrement. Therefore, the axial magnetic field is useful to DC circuit breaker. In this paper, the rotation radius of spiral arc affected by arc rigidity in axial magnetic field is elucidated. The arc rigidity with rotation radius of spiral arc is calculated. As a result, when the appropriate electrode distance and magnetic flux intensity can be chosen, the arc length increases and the arc is interrupted. [Preview Abstract] |
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LW1.00036: Movement Track of Cathode Spot Affected by Applying Alternating Magnetic Field Masashi Shimazaki, Maeda Yoshifumi, Reggie Gustilo, Toru Iwao, Kenji Suzuki The surface treatment is expected for the promotion of circulation production. The oxide layer removal of the metal using the vacuum arc is proposed in the technology for surface treatment. It has the advantage that the high speed removal is possible and the secondary waste does not occur. However, it is the problem that the cathode spot of vacuum arc moves randomly. The movement of cathode spot is controlled by applying a external magnetic field in order to prevent this phenomenon. It has been reported that the retrograde movement is changed by applying a transverse magnetic field. It is considered that the movement in the diagonal direction becomes possible with a synthetic magnetic field derived from the alternating magnetic field and transverse magnetic field. The frequency and current of alternating magnetic field are controlled by using an inverter. In this paper, the movement track of cathode spot affected by applying the alternating magnetic field was elucidated. The movement track of the cathode spot was improved by changing the alternating magnetic field. As a result, when the frequency of alternating magnetic field increases, the length of diagonal direction decreases. [Preview Abstract] |
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LW1.00037: Frequency of Splitting and Moving Direction of Cathode Spot Affected by Transverse Magnetic Field in Vacuum arc. Yuriko Takeda, Soshi Iwata, Yoshifumi Maeda, Reggie gustilo, Kenji Suzuki, Toru Iwao The vacuum arc cathode spot can be applied as pre-treatment of thermal spray because it can remove oxide layer on the metal surface. However, the removal of oxide layer is not enough and re-melting occurs because the cathode spot moves with random manner on the metal surface. Therefore, it is necessary to control the moving direction of the cathode spot. The method of applying a lateral external magnetic field to the arc has been considered in order to control the moving direction of this cathode spot. However, when multiple cathode spots exist, it is considered that the moving direction changes due to the electromagnetic force caused by magnetic field derived from electrodes current. In this paper, the frequency of splitting and moving direction of the cathode spot affected by the transverse magnetic field in vacuum arc is elucidated. While focusing on magnetic flux density, and the respective splitting frequencies and moving directions were calculated. As a result, the splitting frequency is decreased with increasing magnetic flux density, and the movement in a straight line is improved. [Preview Abstract] |
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LW1.00038: Contribution to Re-strike of Arc Affected by Electromagnetic Force in Magnetic Driven Arc. Yutaro Inuzuka, Kazuki Kawasaki, Takashi Yamato, Yoshifumi Maeda, Toru Iwao Magnetic driven arc has been applied to DC breaker. However, several phenomena in magnetic driving arc have not been elucidated. In this paper, the electromagnetic force acting on magnetic driven arc in external magnetic field is calculated. Also, the process of re-strike of arc affected by external magnetic field in magnetic driven arc is elucidated. Specifically, the behavior of magnetic driven arc with external magnetic field is measured by using the oscilloscope and HSVC�iHigh Speed Video Camera�j. The additing an external magnetic field was applied by helmholtz coil. As a result, the electromagnetic force increases with increasing the external magnetic field. The arc mean moving speed increases with increasing the external magnetic field. The re-strike of arc time increases and stagnation time decreases with increasing the external magnetic field. Therefore, the anode spot moving speed increases because the re-strike of arc occurs easily with the external magnetic field. The distance between the arc column and anode becomes shorter and re-strike of arc occurs easily because the arc column precedes the anode spot with the external magnetic field. The re-strike of arc occurs on the extension of electromagnetic force. Therefore, the direction of the electromagnetic force contributes to the re-strike of arc. [Preview Abstract] |
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LW1.00039: Arc Rotation Radius and Driven Force Affected by Frequency of Transverse Rotating Magnetic Field Koki Matsumoto, Toru Shiino, Yoshifumi Maeda, Reggie Gustilo, Kenji Suzuki, Toru Iwao TIG arc welding is used in the case of joining two metals deflection When the lateral gas blew the arc, an inappropriate heat transfer occurs because of the arc deflection. A proposed method of applying transverse magnetic field, in order to prevent the arc deflection, has been considered. One direction of transverse magnetic field only prevents the arc deflection to the lateraled gas direction which is affected by lateral gas. Thus, the control is difficult to achieve one direction affected by transverse magnetic field. When a rotating transverse magnetic field is applied to the arc, the Lorentz force can be applied in any direction. The arc is restrained by this force and it can prevent the arc from deflecting. In this paper, the arc rotation radius and the driven force affected by frequency of transverse rotating magnetic field in atmospheric pressure arc were analyzed. Specifically, the arc rotation radius affected by the magnetic frequency and the magnetic flux density are measured by two high speed video cameras. As a result, the arc rotation radius and the driven force decreases with increasing the frequency of transverse rotating magnetic field. [Preview Abstract] |
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LW1.00040: Image analysis of dc plasma torch using Singular Value Decomposition technique Vidhi Goyal, G Ravi In a recent work using fast imaging diagnostics on a magnetized dc non-transferred plasma torch, it was revealed that plasma column consists of different parts, each governed by a different set of forces, rendering the overall physical processes very complex. The end-on imaging clearly showed the formation of fully three dimensional structures and complex arc root motion. However, standard image analysis using conventional techniques could provide only macroscopic information on the arc root dynamics such as rotation and shunting. Singular Value Decomposition (SVD) is a powerful technique to extract fundamental features of a physical process and has been widely used in laser produced plasmas, tokamaks etc. In the present work, SVD technique has been applied on datasets derived from fast images of the plasma torch. Using this technique, dynamics of each segment of the column have been unraveled for various experimental conditions viz. gas flow rates, currents and magnetic fields. Detailed results will be presented and discussed. [Preview Abstract] |
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LW1.00041: Temperature and Thermal Equilibrium States in Bubbles with Varied Bubble Size and Discharge Energy Kunpeng Wang, Christopher Campbell, Xin Tang, Shariful Bhuiyan, Abdullah Baky, David Staack To optimize plasma-liquid interaction in non-thermal plasma processing of liquids with gas bubbles, we studied the effects of bubble size and discharge energy on temperature and product distribution at equilibrium states in bubbles and seek to control them by varying bubble size and discharge energy. Pulsed energy deposition to methane bubbles was simulated as a constant volume heating process with varied gas heat capacity and compositions. Energy deposition process is highly non-equilibrium and takes place at a time scale of 100-200ns. Gas temperature based on the deposited energy was evaluated. Reaction kinetics and species distribution at this temperature were studied by assuming at thermodynamic equilibrium. Reaction kinetics in methane bubbles showed when temperature is 1500K, it takes about 150ms to reach an equilibrium state. C2 species is highly concentrated and might lead to solid production. At 2500K, the time for equilibrium is only 5us and more C2 species were present in the bubble. Smaller bubbles will have higher temperature for the same energy deposition. Energy deposition to 0.5mm bubbles should be less than 3.5mJ to keep bubble temperature below 1500K. If bubble size is less than 0.2mm, deposition energy needs to be smaller than 0.5mJ to make temperature less than 1500K. Low temperature is preferred because it produces less C2 products and allows longer plasma liquid interaction time. [Preview Abstract] |
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LW1.00042: Effect of dissolved oxygen on the synthesis of copper oxide nanoparticles by atmospheric pressure plasma electrolysis J. Liu, N. Sharai, K. Sasaki Plasma-liquid interactions have drawn much attention due to its unique ability of producing highly reactive species which make it possible for a wide range of materials synthesis. Here, we present a simple one-step route to synthesize copper oxide (CuO or Cu$_{2}$O) nanoparticles by using atmospheric pressure plasma electrolysis system. In this system, a helium plasma was generated via a stainless steel tube which acted as a cathode. The plasma was contacted with the NaCl-containing solution and a copper plate was partially immersed into the solution as the counter electrode. In the work, we investigated the effect of chloridion (Cl$^{-}$) by tuning the concentration of NaCl and also compared the experiments by using solution with different concentration of dissolved oxygen (DO). The results showed that the dissolved oxygen played a key role to determine which kind of copper oxide was formed. In the case of high concentration of DO, cupric oxide (CuO) was synthesized while cuprous oxide (Cu$_{2}$O) was obtained in the case of low concentration of DO. The synthesis processes and mechanism leading to the nanoparticles are also been demonstrated. [Preview Abstract] |
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LW1.00043: Numerical study on discharge generated in a helium bubble in water at atmospheric pressure Wen Yan, Yang Xia, Zhenhua Bi In this work, a 2D simulation of underwater discharge in a helium bubble at atmospheric pressure was performed. The dynamics of the discharge ignition, propagation and the formation of ROS were studied. Upon ignition, the discharge propagated mainly along the gas-water interface until a circle was formed. OH was found to be the dominant ROS in the bubble, followed by O and then H$_{\mathrm{2}}$O$_{\mathrm{2}}$. The influence of the voltage amplitude and the position of needle electrode on the discharge development, reactive species and corresponding fluxes to the gas-water interface was also investigated. As the voltage increased, the discharge was ignited earlier and the propagation path was closer to the gas-water interface. For the case of the needle tip inside the tube, the discharge was initiated as a surface streamer inside the tube, then exited the tube into the bubble with surface hugging discharge mode. For the case of the needle tip outside the tube, an additional volumetric discharge was observed, based on the surface hugging discharge. The densities of O, OH and their fluxes at the gas-water interface increased either by increasing voltage amplitude or moving the needle tip outside of the tube. [Preview Abstract] |
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LW1.00044: Plasma Discharge Development in Dissimilar Multi-liquid Configuration Ali Charchi Aghdam, Tanvir Farouk Plasma discharges in liquids is an emerging field of research and is involved into a wide range of applications -- water purification, fuel reforming, material synthesis etc. Having a high treatment efficiency with low energy consumption is one of the main objectives driving the research agenda. In this work we present a numerical study of nanosecond plasma discharge formation in a multi-liquid system where the dielectric permittivity of the two liquids are significantly different. The simulations are conducted with a recently developed multiphysics model comprising of species conservation equations, Poisson's equation for the electric field and a compressible momentum equation solver. Special attention has been given to the numerical approximation of the electrical forces since they are highly dependent on the fluid property gradients which are difficult to evaluate at the interface discontinuity. Predictions from the model provide insight on the role of interface position relative to the anode tip on the discharge initiation process. It is observed that since the dielectric permittivity is discontinuous at the interface, the electric field is enhanced by a factor that depends on the relative value of the dielectric permittivity of the two liquids. [Preview Abstract] |
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LW1.00045: Status of high throughput plasma water reactor John Foster, Selman Mujovic A pathway to scale-up has been a key obstacle to the practical implementation of plasma-based water purification systems. In an attempt to circumvent this problem, an alternative plasma applicator geometry has been developed. This embodiment features the conversion of pipe flow into thin streams of water, which in turn serve as a dielectric barriers. Plasma is generated in the interstitial spaces between water streams and at the surface of the streams, thereby delivering the requisite treatment dose. Here, we report on preliminary high power operation of this system, treating flows up to 20 liters/min both in batch mode and once-through configuration. Advanced oxidation dose is assessed as a function of input power and pulse frequency, using real time ozone and peroxide sensors. [Preview Abstract] |
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LW1.00046: Remote deflecting plasma source for novel plasma processing Norihiro Kodama, Haruhiko Himura, Takashi Morioka, Deyan Liu, Sadao Masamune, Akio Sanpei, Okada Shigefumi, Kingo Azuma, Takashi Kanki Currently IoT technologies are progressing rapidly, which demands for downsizing and sophistication of mobile devices. Thus, various devices such as sensors and other circuit elements mounted on those must be more miniaturized and complicated. Generally, those are manufactured by producing a plasma containing ions or radical of atoms to be deposited. However, in such a conventional plasma, it is difficult to operate behaviors of ions, radicals, and electrons. Especially, the energy of ions cannot exactly controlled, which frequently causes crucial damages on the surface. This results in deteriorating the device performance and reliability. Therefore, a novel method by which fine processing on the nanoscale can be performed is required. Recently, we propose a novel plasma processing in which only ions having high chemical activity are used for contributing to the formation of thin films or nanostructures. To verify the proposed method experimentally, we have developed an O$_{\mathrm{2}}$ plasma source from which only O$^{\mathrm{-}}$ are extracted and deflected toward a reactor chamber by using an electrostatic lens and a set of magnetic coils. In this meeting, we present the detail of the machine and data obtained from it. [Preview Abstract] |
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LW1.00047: Effect of negative ion density on plasma flow measurement of a Mach probe in DC Ar/O$_{\mathrm{2}}$ plasma I.J. Kang, M.-K. Bae, I.S. Park, S.H. Lee, S.J. Jeong, K.-S. Chung In DC Ar/O$_{\mathrm{2}}$ plasma, axial plasma flow velocity was measured by using a parallel Mach probe. To analyse the effect of negative ion density on the deduction of the Mach numbers, the ratio of upstream to downstream current densities was measured by adjusting the ratio of flow rate of O$_{\mathrm{2}} \quad =$ 0 -- 10 {\%} to that of Ar. Electronegative plasma was performed by adding O$_{\mathrm{2}}$ gas to Ar plasma with a DC filament discharge source. The normal conditions, measured by a cylindrical electric probe, of a DC filament discharge source with heating power (4.3 V/33 A) and discharge power (32 V/0.5 A) are the following: plasma density $=$ 1 -- 3 × 10$^{\mathrm{9}}$ cm$^{\mathrm{-3}}$ and electron temperature $=$ 1 -- 4 eV. To check the effect of negative ion density in term of O$_{\mathrm{2}}$/Ar, negative ion density was estimated by measurement of a cylindrical electric probe. Before analysis of effect of negative ion density, the results of a Mach probe in pure Ar plasma were fit to the data of a laser induced fluorescence system, which composes of a tunable diode laser with a master oscillator power amplifier (MOPA) and fluorescence light collection system, to check plasma flow velocity measured by a Mach probe with an unmagnetized Mach probe theory. For the effect of negative ion density on the deduction of the Mach numbers, variations of Mach numbers were analysed with comparison of pure to negative ion containing plasmas in same pressure. [Preview Abstract] |
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LW1.00048: Scattering of infrared light by charged microparticles using dynamic properties induced by varying electric fields Tatsuki Hangai, Akinori Iwai, Manami Iga, Shigeyuki Miyagi, Osamu Sakai Optical devices (e.g. electronic papers and optical switches) are required to have external controllability for reactions to light. When the size of scattering object can be tuned, we obtain tunable reactions to light. A microparticle is one of the tunable materials for this purpose because a group of microparticles can change scattering of light by aggregation and dispersion, which regulate the effective size of the object. We successfully charged up microparticles (1 - 5 $\mu $m) with both polarities, similar to plasma, and observed their transport by externally applied voltage, like a collective motion in plasma [1]. The intensity of the scattering IR field with wavelength 3.39 $\mu $m was enhanced by their aggregation in our experiment. A tungsten carbide probe whose tip size was smaller than the microparticles was used as an electrode. By collecting the microparticles in advance and irradiating them with the IR laser, we confirmed the relationship between the effective size of the group of microparticles on the tip of the probe and the reflected light intensity to clarify that they can be useful components for future optical devices. [1] I. Laut, C. Räth, L. Wörner, V. Nosenko, S. K. Zhdanov, J. Schablinski, D. Block, H. M. Thomas, G. E. Morfill, Phys. Rev. E 89, 023104 (2014). [Preview Abstract] |
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LW1.00049: Issues with the CFR T4B device Robert Jones In Lockheed-Martin's CFR T4B fusion device the line cusps that pass over the internal rings experience bad magnetic curvature and this will excite instabilities. This turbulence will produce cross field plasma losses to the wall and broaden the cusps. Lockheed-Martin underestimates how wide their cusps will be and overestimates the plasma confinement. [Preview Abstract] |
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LW1.00050: High Voltage Nanosecond Pulser Operating at 30 kW and 400 kHz Morgan Quinley, Timothy Ziemba, Kenneth E. Miller, James Prager, Ilia Slobodov The generation of high voltage nanosecond pulses at high average power is important for a variety of industrial applications including water treatment, semiconductor processing, materials processing, and sterilization. Eagle Harbor Technologies, Inc. (EHT) has previously developed high voltage nanosecond pulsers that operate at 5 kW of average power and pulse at 100 kHz. This work has been extended to higher average power. This new nanosecond pulser can drive capacitive loads (7 nF) to 8 kV with rise times of 55 ns and a 200 ns pulse width. The pulses can be produced at 400 kHz for bursts of 1 ms with a burst repetition frequency of 200 Hz. The output voltage can be modulated between 500 V and 8 kV on the burst timescale. This system can be air or water cooled. EHT will present testing results demonstrating these new capabilities. [Preview Abstract] |
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LW1.00051: Laser Induced Fluorescence Measurements of Ion Beamlets in REVAN David Caron, Thomas Steinberger, John McKee, Costel Biloiu, Earl Scime Plasma doping and etching has become increasingly important for production of three-dimensional semiconductors. To increase the packing density of transistors beyond the levels achievable with \textasciitilde 10 nm feature lithography, industries are moving to three-dimensional structures. Here we present the initial measurements of ion beamlet structure and energy in the Ribbon Experiment for Velocity and Angular distributioN (REVAN). REVAN employs a commercial-style plasma source with an extraction geometry designed to create beams of high energy ions to dope and etch silicon wafers. We will present laser induced fluorescence (LIF) measurements of ion beamlet angle and energy distribution in an argon plasma. The dependence of beam parameters on source RF power, gas pressure, and extraction voltage are investigated. [Preview Abstract] |
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LW1.00052: Study on plasma parameter in oxygen plasma using a hybrid plasma source Kwan-Yong Kim, Kyung-Hyun Kim, Young-Hun Hong, Ho-Jun Moon, ChinWook Chung The characteristics of oxygen plasma are studied in a hybrid plasma source by adjusting the current flow through each source. The hybrid plasma source consists of a bias electrode at the top and an antenna at the bottom, which connected in parallel. A single RF power generator and impedance matching system is used, and the variable capacitor is installed in series at the antenna to control the current flow of each sources. A single reactor is divided into two discharge spaces according to plasma sources. In the primary space, the low-density plasma is generated via the capacitive coupling of the bias electrode, and the O2 gas is decomposed to the O radical. In the secondary space, a high-density plasma is generated via the inductive coupling of the antenna coil, and once again the O2 gas is decomposed to the O radical. It is found that there is a potential dip in the middle of reactor and the potential dip is formed to keep two plasmas quasi-neutrality. In this work, Langmuir probe and optical emission spectroscopy (OES) are used to measure the EEDFs and the emission intensity. By adjusting the current ratio of the bias electrode and the antenna, the change of emission intensity of O species was obtained. [Preview Abstract] |
(Author Not Attending)
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LW1.00053: The Influence of N$_{\mathrm{2\thinspace }}$gas at wafer-less dry cleaning process in mass production system Kyumin Cho, Hyungseok Choi, Yunsung Lee Wafer-Less Dry Cleaning(WLDC) is a process that maintain chamber surface stability as well as other contaminates after etch process are carried out in the chamber. It is important to maintain constant inner circumstance for product quality in mass production system. WLDC has popularly used fluorocarbon and O$_{\mathrm{2}}$ gas to eliminate byproducts. Recently coating materials of etch chamber normally use Y$_{\mathrm{2}}$O$_{\mathrm{3\thinspace }}$and Al$_{\mathrm{2}}$O$_{\mathrm{3.\thinspace }}$But continuous fluorination of coating surface by fluorocarbon and O$_{\mathrm{2}}$ gas influence plasma elements and stability. Although O$_{\mathrm{2}}$ gas is good at chamber cleaning, it has caused side effect. Experimentally O$_{\mathrm{2}}$ addition in fluorocarbon gas base accelerates poly and oxide etch rate. It means chamber wall surface rapidly can be transformed. The focus of our study is on effect of process gas at WLDC for long lasting and constant plasma status. Through gas composition experiments, we have focused on researching role of N$_{\mathrm{2\thinspace }}$gas for replacing O$_{\mathrm{2\thinspace }}$gas and reducing side effects despite of long term use. [Preview Abstract] |
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LW1.00054: Effect of plasma nonuniform on etching profile Wan Dong, Zhongling Dai, Yuanhong Song, Younian Wang With the development of microelectronics industry, atomic layer etching (ALE) increasingly plays an irreplaceable role in realizing higher precision control of etching. In the research, by coupling a fluid/MC model with a trenching model, we simulate the ALE cycle in Ar/CF4 and Ar capacitively coupled plasmas, in which four steps are involved. For the first step in an Ar/CF4 plasma, fluorocarbon (CFx) film is deposited by the CFx radicals. Secondly, we simulate the process of purging the residual gas. The third step is about the Ar positive ion bombardment on the fluorocarbon (CFx) layer in Ar plasma; In the last step the residual gas is removed. Based on the two-dimensional fluid model coupled with ion MC model, the parameters of etching, for example the particle densities as well as electron and ion energy distributions, are utilized to simulate the etching profiles in the trenching model. Our results show that the etching profiles and etching uniformity can be improved with the etching rate increasing by changing the bias voltage waveform as well as the ion bombardment. [Preview Abstract] |
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LW1.00055: Fluorine Radical Production from Dissociation of CF$_{\mathrm{4}}$ in Inductively Coupled Plasma Mitchell Paul, Costel Biliou, Earl Scime Defining parameters for the fluxes of fluorine radicals in an ion assisted directional reactive etch (DRE) device are presented. The etching device consists of an inductively coupled plasma source and angular distribution controlled ion extraction optics. Optical emission spectra of CF$_{\mathrm{4}}$/O$_{\mathrm{2}}$ plasma were analyzed over the 200 to 800 nm wavelength range and characteristic spectral features of CF$_{\mathrm{4}}$ and its dissociation byproducts identified. Fluorine radical production rates were inferred by actinometry from ratios of integrated spectral intensities of F lines and trace rare gas lines. F radical production was investigated in correlation with precursor gas pressure and RF input power. The obtained results allow for optimization of the ion assisted etch process in CF$_{\mathrm{4}}$/O$_{\mathrm{2}}$ plasma. [Preview Abstract] |
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LW1.00056: Control the standing wave effect by increasing low frequency source power. Eunjeong Kim We make metal lines along the circuit patterns of semiconductors. We faced one problem in the process of etching this metal line. The depth of metal line was deep at the center of wafer. This phenomenon reduced the separation distance between the metal line and the contact hole, which led to leakage current. The standing wave effect is the cause of this phenomenon. We etch the wafer in a CCP Chamber using a symmetric electrode. The standing wave effect is formed whenever two progressive waves of same amplitude and wavelength travel in opposite directions and superimpose. The electron density is highest at the center of the wafer where this wavelength overlap. So the etching amount at the center is peak. The source power we use is 13MHz and 100MHz . Wavelength is inversely proportional to the frequency of the source power. The lower the frequency, the greater the wavelength. As a result, the standing wave effect is reduced and the electron density in the chamber becomes uniform. We tried to research a best 13MHz source power to reduce the standing wave effect. As a result, We improved the depth dispersion of the metal line between the center and edge points of the wafer was improved by 50 percent. [Preview Abstract] |
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LW1.00057: Synthesis of boron nitride using a micro hollow cathode discharge deposition reactor. Claudia Lazzaroni, Hiba Kabbara, Salima Kasri, Ludovic William, Vianney Mille, Xavier Aubert, Guillaume Lombardi, Alexandre Tallaire In this study, a Micro Hollow Cathode Discharge reactor is used to deposit hexagonal boron nitride (h-BN), a strategic material which is highly demanded for electronic and optoelectronic applications. The deposition reactor is composed of two chambers and the micro-plasmas, arranged into an array, are located at the junction between them. The array consists of an anode-dielectric-cathode sandwich through which several holes of 400 \textmu m in diameter are drilled. The higher pressure chamber (several tens of mbar), favors the production of high density plasma, and consequently high nitrogen dissociation, while the lower pressure chamber (several mbar) limits the nitrogen recombination. The polarizable and heating substrate holder is located in the lower pressure chamber where the boron precursor is injected. The polarization of the substrate holder allows the discharge to be expanded from the holes to the substrate. The deposited films are characterized by X-ray diffraction and Raman spectroscopy to evaluate the h-BN phase purity and quality, and by scanning electron and confocal laser microscopy to observe the surface morphology. The influence of the operating conditions (pressure, gas mixture, bias voltage,..) on the deposited film properties will be presented. [Preview Abstract] |
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LW1.00058: Study of Irradiation Damage Induced by Helium Ion in Fe-based Metallic Glass Xianxiu Mei, Xiaonan Zhang, Jianbing Qiang, Younian Wang The changes in structure and surface morphology of metallic glasses Fe$_{\mathrm{80}}$Si$_{\mathrm{7.43}}$B$_{\mathrm{12.57}}$ and Fe$_{\mathrm{68}}$Zr$_{\mathrm{7}}$B$_{\mathrm{25}}$ before and after the irradiation of He ions with the energy of 300keV were investigated, and were compared with that of the tungsten. In metallic glass Fe$_{\mathrm{80}}$Si$_{\mathrm{7.43}}$B$_{\mathrm{12.57}}$, when the fluence of He ions was up to 4×10$^{\mathrm{17}}$ions/cm$^{\mathrm{2\thinspace }}$(19dpa), crystallization occurred, and a small amount of metastable $\beta $-Mn type phase nanocrystals formed. When the fluence increased to 1×10$^{\mathrm{18}}$ions/cm$^{\mathrm{2\thinspace }}$(47dpa), the quantity of nanocrystals increased and metastable $\beta $-Mn type phase transformed into $\alpha $-Fe phase and tetragonal Fe$_{\mathrm{2}}$B phase. Then orthogonal Fe$_{\mathrm{3}}$B phase and $\beta $-Mn type phase formed and were added to the nanocrystals as the fluence increased to 1.6×10$^{\mathrm{18}}$ions/cm$^{\mathrm{2}}$(69dpa), while metallic glass Fe$_{\mathrm{68}}$Zr$_{\mathrm{7}}$B$_{\mathrm{25}}$ maintained amorphous under the He ion irradiation, till the fluence was up to 1.6×10$^{\mathrm{18}}$ions/cm$^{\mathrm{2\thinspace }}$(69dpa). This indicates that the irradiation resistance of Fe$_{\mathrm{68}}$Zr$_{\mathrm{7}}$B$_{\mathrm{25}}$ is better. After the irradiation, different damage morphologies were exhibited on the surfaces of the two kinds of Fe-based metallic glasses. When the fluence was 1.6×10$^{\mathrm{18}}$ions/cm$^{\mathrm{2}}$, cracks and ductile shear steps appeared on the surface of metallic glass Fe$_{\mathrm{80}}$Si$_{\mathrm{7.43}}$B$_{\mathrm{12.57}}$, and spalling as well as brittle fracture morphology appeared on the surface of metallic glass Fe$_{\mathrm{68}}$Zr$_{\mathrm{7}}$B$_{\mathrm{25}}$. However, blisters and spallings occured on the surface of tungsten at the irradiation fluence of 1×10$^{\mathrm{18}}$ions/cm$^{\mathrm{2}}$, and with the increase of irradiation fluence, the spalling phenomenon became more serious. Thus the irradiation resistance of Fe-based metallic glasses is better than that of tungsten. [Preview Abstract] |
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LW1.00059: Fabrication of glucose fuel cell using carbon nanowalls as anode electrode Hitoshi Nozaki, Keigo Takeda, Mineo Hiramatsu Glucose fuel cell (GFC) is a promising implantable battery because of the abundance of glucose in body tissue and the possibility of stable power generation through the coupling of the glucose oxidation and oxygen reduction reactions. Glucose is oxidized at the surface of catalytic platinum nanoparticles (Pt-NPs) on the anode, and proton is produced. An ionomer layer as proton conducting membrane is held between anode and cathode. Oxygen is reduced to water at the cathode surface composed of nanocarbon. Since the efficiency of GFC depends on the catalytic ability to oxidize glucose at the anode, structure optimization of anode with Pt-NPs is of great importance in realizing high performance of GFC. Here, carbon nanowall (CNW) film was used as a supporting material of Pt-NPs. CNWs are vertically standing few-layer graphenes to form a self-supported network of wall structures with large surface area. CNW film was grown on SiO2 substrate by inductively coupled plasma enhanced chemical vapor deposition employing CH4/H2/Ar mixture. The CNW surface was decorated with Pt-NPs by the reduction of chloroplatinic acid to form anode electrode. Anode area (Pt-NP/CNWs) was coated with ionomer to form proton exchange membrane. Then the entire area was covered with cathode comprising carbon black embedded in ionomer. The prototype of GFC was immersed in phosphate buffered saline containing 10 mM glucose, and electrochemical measurement was conducted. [Preview Abstract] |
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LW1.00060: Cold plasma processing of biochar using point-to-point corona discharge in atmospheric pressure dry air Shuzheng Xie, Patrick Pedrow, Karl Englund Cold plasma generated from a gas admixture of helium and dry air with 60 Hz AC voltage at 6.5 kV RMS was utilized to process biochar. We expect reactive oxygen and nitrogen species (RONS) to be generated in the cold plasma and that these chemical radicals will modify the biochar. Processed samples are immersed in distilled water after which the pH of the solid/water mixture is measured. pH analysis shows processed samples/water admixture has lower pH, indicating plasma process introduces more acidic group to the biochar. After pH analysis the solid biochar granules are reclaimed from solution and the solute is evaluated for carbon and nitrogen content resulting from material leaching into the distilled water. FTIR spectra are measured for dry samples of biochar before and after immersion in the distilled water. Experimental results indicate that new oxygen- and nitrogen- containing functional groups have been introduced to the surface of the samples. Our current hypothesis is that the cold plasma processing converts recalcitrant biochar mass into labile biochar mass, resulting in and enhanced amount of water-extractable carbon. [Preview Abstract] |
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LW1.00061: Fluid Modeling of Microwave Plasma under an External Magnetic Field Masayuki Takahashi, Naofumi Ohnishi A dense plasma is ignited when an intense microwave is focused on using focusing devices, which is utilized in a microwave rocket system. A thrust performance of the microwave rocket was measured by flight demonstration, which indicated that its thrust performance drastically decreased with a decrease in an ambient pressure. Takahashi and Ohnishi numerically described that speeding up in the plasma propagation and a decrease in the energy absorption caused the performance degradation in the microwave rocket. Applying an external magnetic field into the rocket nozzle was proposed to improve the thrust performance by confining the plasma inside the rocket nozzle and enhancing a shock wave. However, a multi-dimensional dynamics of the microwave plasma under the magnetic field was not examined in the previous studies. In this study, a plasma fluid model is developed to capture the multi-dimensional plasma transport during the microwave irradiation when the magnetic field is applied to the discharge domain. The discharge pattern obtained by the fluid model is compared with that reproduced by a particle model to check a validity of the fluid model developed by us. [Preview Abstract] |
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LW1.00062: Spectroscopic study of an iodine plasma in a low pressure RF-ICP ion source Florian Marmuse, Theo Courtois, Jean-Paul Booth, Cyril Drag, Ane Aanesland, Pascal Chabert Iodine is being considered as an alternative to Xenon for plasma propulsion, mainly because of its lower cost and possibility for solid storage. However, iodine plasmas are less well understood than Xenon plasmas, making a need for reliable diagnostic measurements to validate the models of iodine plasmas. We present initial measurements on two iodine plasma systems: an RF-CCP plasma in a closed cell (around 50 Pa), and an RF-ICP plasma (PEGASES plasma source) with flowing I2 gas in the pressure range 0.2-20 Pa. Several diagnostics are presented: emission spectroscopy, laser absorption spectroscopy, cavity ring-down spectroscopy, and a RF compensated Langmuir probe. Absorption from excited states of atomic iodine (at 804, 906 and 911nm) were measured using a cw Ti:Sa laser. Ground state I atoms were measured by the magnetic-dipole allowed spin-orbit transition at 1315nm using a diode laser, either by multi-pass absorption or by cavity ring-down spectroscopy (for greater sensitivity). The absolute atom density was deduced using the transition strengths found in the literature, and the gas temperature was deduced from the Doppler width. The electron density and temperature was deduced from the RF-compensated Langmuir probe. An early comparison with a global model is presented. [Preview Abstract] |
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LW1.00063: Abstract Withdrawn
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LW1.00064: 3D Particle-in-Cell simulation of the ExB electron drift instability in Hall thrusters: effect of the dielectric surfaces on the anomalous transport Gwenael Fubiani, Jean-pierre Boeuf, Laurent Garrigues Kinetic drift instabilities are the likely cause for the anomalous electron transport in Hall-effect thrusters (HETs). This work is a continuation of previous efforts to model drift waves in HETs with a Particle-In-Cell (PIC) algorithm [1]. The latter demonstrated the occurrence of an Electron Cyclotron Drift type Instability (ECDI). The model had a couple of simplifying assumptions in order to speed-up the calculation and pinpoint the mechanisms leading to the formation of the instability. The electron transport was decoupled from ionization and neutral transport, collisions with neutrals were neglected, the magnetic field had solely an axial profile and the simulation domain was 2D (axial-azimuthal plane). In this work, we address the impact of the ceramic walls on the properties of the instabilities. The simulations are performed with a 3D PIC model (parallelized using both OpenMP and MPI). We will analyse: (1) the characteristics of the instability and the anomalous transport versus the discharge power, (2) the effect of the applied discharge voltage on the plasma properties and lastly, (3) the incidence of the numerical capacitance on the convergence time of the simulation.\\ \\$[1]$ J.P. Boeuf et al., Physics of Plasmas \textbf{25}, 061204 (2018) [Preview Abstract] |
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LW1.00065: Stabilization of lean flames by nanosecond sparks Sergey Stepanyan, Nicolas Minesi, Erwan Pannier, Gabi-Daniel Stancu, Christophe Laux Flame stabilization by plasma has been demonstrated for various combustors and using various types of plasma discharges. The mechanism of this stabilization is clearly related to the production of active species by the plasma and its heat release. However the exact roles of these factors have not been determined, particularly because of the complexity of the considered systems. The energy initially deposited in the plasma in the form of heat can be converted toward the production of active species or the development of hydrodynamic effects that enhance the combustion process. Measurements of active species number densities and temperatures during the combustion initiation~must be performed simultaneously with measurements of the discharge parameters. In this work we use a nanosecond spark to stabilize a lean premixed methane turbulent flame (Re$=$30000). We will report on measurements of flame/gas temperature, electron temperature, and electron number density. [Preview Abstract] |
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LW1.00066: Characterization of plasma properties in a hollow cathode discharge Nathaniel Wirgau, John Foster An important life limiter in conventional gridded ion and Hall thrusters is lifetime of the hollow cathode assembly. The cathode’s lifetime is a function of the barium supply within the insert. While barium can be lost from the cathode via gas phase diffusion, models predict that significant barium recirculation within the insert actually occurs. The recirculation and transport of barium is dependent on plasma conditions prevailing in the hollow cathode. Presented here are plasma measurements made within the hollow cathode under conditions of spot and plume mode operation. Ion acoustic wave spectra is also examined in an attempt to assess recirculating barium concentration within the insert region using krypton as a propellant. [Preview Abstract] |
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LW1.00067: Hydrogen gas sensing performance of high-dimensional tungsten oxide fuzz (He induced nanostructure) Yoshihiro Kimura, Kenzo Ibano, Kazuki Yuzawa, Kenya Uehata, Heun Tae Lee, Yoshio Ueda Characteristic nano-fiber structure is formed by He plasma irradiation to metal surfaces at certain temperatures. This nano-fiber structure, usually called `fuzz', is expected to be applied to catalysts and sensors because of their remarkably large surface area due to high-dimensionality. Also, it is known that tungsten oxide has a promising hydrogen sensing ability through redox. Therefore, hydrogen sensitivity of He-induced tungsten fuzz was examined. A thin film of tungsten was formed on a quartz glass plate and tungsten fuzz was made on this by He plasma irradiation using an ECR plasma apparatus. Then, thermal oxidation of the tungsten fuzz was performed in air. The tungsten-oxide fuzz samples were placed in a glass furnace, then resistivity changes by introducing hydrogen containing air were measured as a function of surface temperature. Influence of detailed fuzz structure and oxidation time on the sensing performance were investigated. [Preview Abstract] |
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LW1.00068: Gaseous Plasmonic Resonators for Metamaterial Applications Roberto Colon Quinones, Thomas Underwood, Mark Cappelli We examine the properties of a gaseous plasma resonator generated by focusing a high-energy laser pulse through a lens and into a gas. An analytical model is presented describing the scattering resonance of these near-ellipsoidal plasmas and its dependence on their eccentricity and intrinsic plasma properties. This dependence is confirmed through Ku band transmission experiments of a waveguide with an embedded single plasma element and through optical diagnostics of the laser-induced plasma. The described resonator has the potential to be used as the building block in a new class of metamaterials with fully three-dimensional structural flexibility. [Preview Abstract] |
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LW1.00069: Lattice resonances in two-dimensional plasma photonic crystals: experiments and simulations. Fabio Righetti, Benjamin Wang, Mark Cappelli We describe the experimental verification of lattice resonances in two-dimensional photonic crystals constructed from an array of gaseous plasma columns. Enhancements are seen in the extinction of normal incidence transverse electric electromagnetic waves when the localized surface plasmon modes of the plasma columns are shifted into the vicinity of the photonic crystal Bragg resonances. Simulations and experiments are in reasonable agreement and confirm the appearance of a Fano-like profile with deep and broad extinction bands. The broadening of the spectra as surface plasmon modes come into coincidence with Bragg gaps suggest that the Bragg fields couple strongly into the radiating Mie dipoles to drive enhanced damping of the photonic crystal resonance. [Preview Abstract] |
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LW1.00070: Novel semiconductor nanocomposites for plasma electronic systems Aleksandr Mustafaev, Rostislav Smerdov The realisation of photon-enhanced thermionic emission (PETE) process for solar concentrators allows to integrate photovoltaic and thermionic effects in a single device thus facilitating a significant increase in the overall efficiency. The prototype PETE concentrator with semiconductor (GaN) electrodes is described. The quantity of incident photons with energies greater than the band gap of GaN (E$_{g}$ = 3.3 eV) does not exceed 1 $\%$ of their total amount. Further research on porous silicon (PS) and PS-based nanocomposites for electrode synthesis is required, since a possibility to modify the E$_{g}$ of such materials in a wide range from 1 to 3 eV exists due to the quantum confinement effect and considerable capabilities for surface functionalisation. The development of anodes for thermionic plasma energy systems requires the creation of unique materials characterised with low electron work function ($\phi$$_{a}$). The use of a nickel-based anode coated with graphite/graphene layers intercalated by cesium atoms allowed to achieve a significant decrease in the electron work function ($\phi$$_{a}$ values amount to less than 1 eV), thus resulting in a threefold increase in energy conversion efficiency.\footnote{A.S. Mustafaev et al., \textbf{J. Appl. Phys.} 2018. 123. In print} [Preview Abstract] |
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LW1.00071: Fluid simulations of plasma-based microwave power limitation Antoine Simon, Gerjan Hagelaar, Thierry Callegari, Laurent Liard, Olivier Pascal, Romain Pascaud This paper presents numerical simulations of an experimental plasma-based power limiter for microwave transmission lines, aiming to protect receiver systems from high power microwaves. The system under study features a microstrip transmission line immersed in 10 Torr argon gas, coupled with a micro-hollow cathode discharge sustaining a certain level of pre-ionization at a given point along the line, which enables rapid ignition of a protective plasma discharge as soon as the microwave power exceeds a certain limit of the order of 1 W. The formation of this plasma discharge and its effect on the microwaves are simulated self-consistently using a 2D multi-fluid code including Poisson's equation and a microwave simulation module. The simulation results are compared with various electrical and optical measurements, and help to interpret these experimental data. [Preview Abstract] |
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LW1.00072: Synthesis of Silver Nanoparticles in Ionic Liquids by Electron Irradiation Angela Capece Silver nanoparticles exhibit unique optical, catalytic, and antibacterial properties as a result of their shape and size, making them useful for a variety of applications. Conventional nanoparticle synthesis methods often require high pressures and the use of toxic materials such as organic solvents, reducing agents, and stabilizers. However, plasma synthesis in ionic liquids provides an alternative that circumvents these requirements. As a result of their low vapor pressure, ionic liquids can be combined with low-pressure plasmas to produce metal nanoparticles through the reduction of dissolved metal salts by the reactive species produced in the plasma. In this work, we demonstrate the synthesis of silver nanoparticles by irradiating a solution of AgBF4 powder in the ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, with a 15-kV electron beam. The liquid droplet was imaged during irradiation using a field emission scanning electron microscope (SEM). The size and morphology of the resulting nanoparticles were characterized using SEM, and the particle composition was determined using energy dispersive X-ray spectroscopy and X-Ray photoelectron spectroscopy. [Preview Abstract] |
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LW1.00073: Synthesis of nanomaterials by means of pulsed anodic arc discharge Carles Corbella Roca, Sabine Portal, Denis Zolotukhin, Luis Martinez, Michael Keidar Nanoparticles and two-dimensional materials, such as graphene and nanotubes, have been deposited by means of anodic arc discharge in helium atmosphere excited with a square-wave modulated signal. Combination of Langmuir probe diagnostics and optical emission measurements provided plasma parameters of the pulsed discharge. Plasma species dynamics has been described using computational models. The obtained samples were characterized with Raman spectroscopy and scanning electron microscopy (SEM). The structural properties of the nanomaterials synthesized in pulsed arc mode, as well as their growth rates and conversion efficiency of the ablated anode, are compared to reference samples grown in dc continuous arc mode. This deposition method is promising for the fabrication of semiconducting nanomaterials with tuneable electrical and optical properties. [Preview Abstract] |
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LW1.00074: Development of the high-current plasma modulators using Pierce instability. Aleksandr Mustafaev, Artem Grabovskiy, Boris Klimenkov, Vladimir Soukhomlinov, Viktor Kuznetsov At present, the problems of current control in the electrical circuits of space nuclear power plants are topical [1]. In this talk results of experimental studies of the diode and triode current modulators, intended for use in terrestrial and space current conversion systems are presented. These devices effect current modulation through propagation of plasma structures in the electrode gap and does not require any use of external forces. Such structures are formed through propagation of electronic Pierce instability in plasma. Experiments conducted in a Knudsen diode with a Cs-Ba filling demonstrated the feasibility of full modulation of current at voltage of 5-6 V and discharge current density of \textasciitilde 10 A/cm$^{\mathrm{2}}$. With electrode gap 0.2-2.0 mm wide, a stable modulation of current and voltage with frequencies of 5-20 kHz and complete current cut-off existed at Cs pressures of 1,5\textbullet 10$^{\mathrm{-3}}$-3,5\textbullet 10$^{\mathrm{-3}}$ Torr. Investigations of triode device demonstrated that mechanisms of discharge extinction and spontaneous breakage are associated with nonlinear oscillations. Stable modulation at frequencies of 1-10 kHz of specific electric power of 5 kW/cm$^{\mathrm{2}}$ and an efficiency of more than 95{\%} was obtained at the anode voltage 50 V. [1] A. Mustafaev, A. Grabovskiy, O. Murillo, V. Sukhomlinov, V. Kuznetsov. Cont. pap. of the 44$^{\mathrm{th}}$ EPS Conference on Plasma Physics. Vol. 41F, P5.309. [Preview Abstract] |
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LW1.00075: High fidelity three-dimensional simulations of thermionic energy converters Nathan Cook, Jonathan Edelen, Christopher Hall, Paul Moeller, Robert Nagler, Jean-Luc Vay Thermionic energy converters (TEC) are a class of thermoelectric devices, which promise improvements to the efficiency and cost of both small- and large-scale electricity generation.~A TEC is comprised of a narrowly-separated thermionic emitter and an anode.~Simple structures are often space-charge limited as operating temperatures produce currents exceeding the Child-Langmuir limit.~We present results from 3D simulations of these devices using the particle-in-cell code Warp, developed at Lawrence Berkeley National Lab. We demonstrate improvements to the Warp code permitting high fidelity simulations of complex device geometries. These improvements include modeling of non-conformal geometries using mesh refinement and cut-cells with a dielectric solver. We also consider self-consistent effects to model Schottky emission near the space-charge limit for arrays of shaped emitters. The efficiency of these devices is computed by modeling distinct loss channels, including kinetic losses, radiative losses, and dielectric charging.~We demonstrate many of these features within an open-source, browser-based interface for running 3D electrostatic simulations with Warp, including design and analysis tools, as well as streamlined submission to HPC centers. [Preview Abstract] |
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LW1.00076: Removal of cyanobacteria from water via advanced oxidation processes Janis Lai, John Foster Harmful algal blooms (HAB) such as those derived from cyanobacteria pose challenges to drinking water derived from surface sources such as reservoirs and lakes. The treatment is complex in that the algae-derived toxins exists both within the algae cell as well as in the water, so simple destruction of the cells can lead to additional toxin release. Any effective treatment approach must manage both toxin sources, keeping the total concentration below the provisional maximum concentration limit. We investigate the effectiveness of a plasma-derived treatment method on mitigating bloom-derived contamination of drinking water. Here, we investigate the capacity of the discharge approach to selectively treat the microcystin in solution as opposed to lysing the cells. Additionally we quantify plasma reaction conditions necessary to both lyse cells and treat released microcystin in solution. This way, we assess the capacity of the plasma-based method to comprehensively address persistent toxic algal blooms. [Preview Abstract] |
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LW1.00077: Atmospheric Pressure Plasma Propagation through Porous Bone Scaffolding Runchu Ma, Juliusz Kruszelnicki, Mark J. Kushner Bone scaffolding in the form of porous dielectric media has been of interest in the medical field for the purpose of tissue regeneration following trauma. Low temperature plasmas can be used to improve cell growth in the scaffolding by surface functionalization through sterilization, increasing hydrophilicity and deposition of non-reactive surfactants. In this study, we investigate the behavior of atmospheric pressure plasmas propagating inside porous media having the topography of bone scaffolding using the plasma hydrodynamic modeling platform, \textit{nonPDPSIM}. A dielectric barrier discharge with a 1 mm gap generates plasma in dry air which then propagates into a dielectric having pores 150 $\mu $m diameter, 40 $\mu $m openings between pores and 100{\%} interconnectivity. We found that electrons initially propagate into the gaps as Townsend avalanches following the electric field which produces some shadowing. As the plasma develops in the pores, surface charging then leads to formation of Surface Ionization Waves (SIW). As the charging continues, microdischarges form between pores. The initial breakdown process is little unaffected by the alignment of the pore-chains with the applied electric field. However, as this alignment became more orthogonal, SIWs preferentially form on one side of the pore-chain, leading to non-uniform treatment of internal surfaces. [Preview Abstract] |
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LW1.00078: Surface Sterilization of Spacecraft for Planetary Protection with Plasma Jet Array James Prager, Timothy Ziemba, Jonathan Miller Contamination Control for Planetary Protection is a serious issue as we explore solar system bodies with missions that have the potential for detecting life. Currently, dry heat microbial reduction (DHMR) and vapor hydrogen peroxide (VHP) are the only microbial reduction methods approved for planetary protection. DHMR is extremely time consuming and chamber time is difficult to schedule, while the use of VHP is not usable for some state-of-the-art electronics and materials. Eagle Harbor Technologies, Inc. (EHT) has developed an array of atmospheric pressure plasma jets (APPJs) to kill endospores on the surfaces spacecraft. The APPJ array is driven by an EHT Nanosecond Pulser. A microbiology lab at Edmonds Community College investigated a wide range of parameters to evaluate pulse and gas parameter efficacy for killing endospores. During the Phase I, they demonstrated a six-log reduction of endospores in petri dishes and provided preliminary evidence of real-world sterilization. Additionally, an FPGA and SDRAM continued to function after plasma exposures showing that this treatment will not impact sensitive electronics. [Preview Abstract] |
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LW1.00079: Ozone densities in the effluent of an APPJ Brayden Myers, Katharina Stapelmann Ozone concentrations in the effluent of a plasma jet are measured using absorption spectroscopy. A COST atmospheric pressure plasma jet is used with a total plasma volume of 30 cubic mm [1]. The COST source is a reference source built to better characterize the parameters of -APPJs. -APPJs are being actively examined for applications in the medical field, including sterilization and wound treatment. Gas flows of 1-1.5 slm of helium, along with small admixtures of oxygen, less than 1%, are used. The absorption spectra are acquired using a broadband UV light source and an Echelle Spectra Analyzer. Densities of ozone are obtained by focusing on the Hartley band, which is characterized by a strong absorption peak at 255 nm [2]. Variable flow rates of oxygen and helium are considered, as well as changes in applied voltage to the plasma. [1] J. Golda et al., J. Phys. D: Appl. Phys., 49, 2016 [2] D. Ellerweg et al., Plasma Sources Sci. Technol., 21, 2012 [Preview Abstract] |
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LW1.00080: Characterization of a flexible dielectric barrier discharge Sierra Jubin, Sophia Gershman, Shurik Yatom, Yevgeny Raitses A flexible dielectric barrier discharge (DBD) device is well-suited for use in applications where sensitive tissue is to be treated. Such a device is capable of generating cold, homogeneous plasma in ambient atmosphere and can be used to treat large surfaces. The DBD is readily made with printed circuit board technology, and its effectiveness as an antimicrobial treatment in wound healing has previously been investigated.\footnote{B K H L Boekema \textit{et al.} 2016, \textit{J. Phys. D: Appl. Phys.} \textbf{49} 044001} In this work, we have built and characterized the operation of a flexible DBD device with a compact power supply. We have evaluated the plasma characteristics and the plasma-induced chemistry by means of optical emission spectroscopy and spectral and fast imaging. The production of chemically active species\footnote{J Ehlbeck \textit{et al.} 2011, \textit{J. Phys. D: Appl. Phys.} \textbf{44}, pp.13002} is evaluated in different environments, such as in ambient atmosphere, in conditions of increased humidity, and in the vicinity of a hydrogen peroxide carrier. [Preview Abstract] |
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LW1.00081: Gas temperature control of low-frequency helium plasma jet using Peltier device for biological experiments Shinji Yoshimura, Mitsutoshi Aramaki, Yoko Otsubo, Akira Yamashita, Kazunori Koga We are planning to conduct experiments on the biological effects of plasma irradiation to fission yeasts, one of popular model organisms. We adopted a commonly-used low-frequency (LF) helium plasma jet as a plasma source because of its accessibility. In addition to stability and reproducibility of the plasma, which are obviously important for such biological experiments, a good control of the gas temperature is crucial especially when using temperature-sensitive mutants. The gas temperature of an atmospheric-pressure LF plasma jet is generally around room temperature in the initial stage of the discharge. However, the gas temperature in our experimental setup gradually increased with time up to 70 degrees Celsius in one minute. In order to prevent the gas heating, we attempted to actively control the temperature of helium gas supplied to the discharge region by using a Peltier device. A plasma jet with almost constant gas temperature, which is below critical temperature, for more than one minute has successfully been obtained. Some preliminary results of direct plasma jet irradiation to fission yeasts with controlling gas temperature will be presented. [Preview Abstract] |
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LW1.00082: Hall-Effect Thruster with Wide Acceleration Zone, Ballistic and Magnetic Beam Focusing Oleksii Girka, Yuliia Balkova, Sergey Reva, Olexander Bizyukov An efficient, long-life Hall effect thrusters (HET) would be attractive for a wide range of aerospace missions [1], research tasks [2-3] and technological applications [4]. The objective of research is developing focusing system for HET with wide acceleration zone. Previous research [3] showed attractive set of applications. Average ion energy of anode layer thruster was 2 keV, which is high enough for some surface treatment applications. Therefore scheme of Hall-effect thruster with wide acceleration zone, ballistic and magnetic beam focusing is proposed. Magnetic field distribution in reversed magnetic focusing system and trajectories of Hydrogen and Argon ions with energy of 800 eV in inhomogeneous magnetic field are calculated, optimal values of currents in magnetic field coils are determined. Technical documentation on source manufacturing is completed and further experimental testing is planned. [1] S. Mazouffre. Plasma Sources Sci. Technol. 25 (2016) 033002 (27pp) [2] J. Kurzyna, et. al. Laser and Particle Beams, 36(1) (2018), 105-114 [3] O. Girka, et. al. Rev. Sci. Instr. 83 (2012), 083501 [4] O. Girka, et. al. Nukleonika, 60(2) (2015), 327-330 [Preview Abstract] |
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LW1.00083: Experimental characterization of a new design of double stage Hall Thruster, ID-Hall: relevance of the concept Freddy Gaboriau, Loic Dubois, Alexandre Guglielmi, Jean-Pierre Boeuf In conventional Hall thruster, the same electric field provides electron energy for ionization and controls the ion acceleration, thus thrust and specific impulse are closely linked. The concept of double-stage Hall thruster (DSHT), where ionization is separated and controlled independently from ion acceleration, allows separating thrust and specific impulse. The challenge is to obtain a high degree of ionization in the first stage, an efficient extraction of the ions from the ionization region to the acceleration stage with limited charged particle losses. To address this issue, we propose a new concept of DSHT called ID-Hall (Inductive Double-stage HALL Thruster) where the ionization stage is a cylindrical magnetized RF source placed inside the inner cylinder and magnetically connected to the standard Hall acceleration stage. ID-Hall thruster will be presented and characterized both in single stage mode and double stage mode by measuring plasma density, electron temperature, total extracted ion current and ion energy distribution function in the plume of the thruster. Finally, the relevance of the DSHT concept will be discussed. [Preview Abstract] |
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LW1.00084: SPECT3D, Imaging and Spectral Analysis Package Sudhir Kulkarni SPECT3D is a collisional-radiative spectral analysis package designed to compute detailed emission, absorption, or x-ray scattering spectra, filtered images, XRD signals, and other synthetic diagnostics. The spectra and images are computed for virtual detectors by post-processing the results of hydrodynamics simulations in 1D, 2D, and 3D geometries. SPECT3D can account for a variety of instrumental response effects so that direct comparisons between simulations and experimental measurements can be made. We will present new features of SPECT3D and highlight their application to the analysis of HEDP experiments. Recent additions to SPECT3D include an updated version of Prism's Atomic Database that incorporates NIST atomic data version 5.0 and improves the consistency for modeling He- and Li-like satellite transitions. X-Ray Thompson scattering calculation times have been improved for the RPA model, and multi-threading has been added for the short characteristics method. Future development plans for SPECT3D will also be discussed. [Preview Abstract] |
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LW1.00085: Vectorial Electric Field Characterization Of Plasmas Using An Optical Probe Farah Aljammal, Gwenael Gaborit, Laurence Galtier, Guillaume Revillod, Sylvain Iseni, Remi Dussart, Lionel Duvillaret Since several years, there has been an impressive revival of interest in the characterization of discharges and Plasma due to their wide range of application. Our study is focusing on the measurement of electric (E) field associated to non-equilibrium atmospheric pressure plasmas such as DBD, ionisation waves(IW) and micro discharges. For that purpose, we have designed and realized a fully dielectric and millimeter sized optical probe based on the Pockels effect, also called electro-optic (EO) effect[1].This probe is coupled to an optoelectronic measurement bench delivering a voltage proportional to one E-field eigen component. The measurement can be performed in real time from some 10 Hz up to several GHz with a dynamic exceeding exceeds 120 dB. The investigation of the very near field of the ionized media concerns both AC and DC plasma: -determination of the breakdown voltage/field strength, -transient evolution of the field vector induced IW, -vectorial mapping of two eigen field components[2], -non-disturbing probe in the field to be measured. Further improvements of the EO technique will also be presented. [1] G. Gaborit et al, IEEE Trans.on Plas. Sci. 42(5),1265-1273,2014. [2] arXiv:1709.03109v1 [physics.plasm-ph] [Preview Abstract] |
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LW1.00086: Investigation of optical spectroscopy for the different phases of helium . Nelly Bonifaci, Joel Rosato, Zhiling Li, Jussi Eloranta, Vyacheslav Shakhatov, Vladimir Atrazhev The micro-plasma created by corona discharge was established around the point electrode in gas and supercritical helium. The visible light from the microplasma was investigated by optical emission spectroscopy as a function of temperature and pressure. The impurity in the helium gas can be considered the addition to allow acquiring the optical emission spectra from not only the helium but also nitrogen and hydrogen. Profiles of the high resolution emission spectra for several species such as H, N$_{\mathrm{2}}$, N$^{\mathrm{+}}_{\mathrm{2}}$, He$_{\mathrm{2}}$ and He were presented and compared. [Preview Abstract] |
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LW1.00087: Thrust measurement of an electro-magnetic thruster applying a pseudo-spark discharge Masayuki Watanabe, Hayata Maebara, Toru Fukata, Hikaru Nakamura, Atsuri Miyauchi, Takaharu Kamada An electro-magnetic thruster is one of thrust systems for outer space. The plasma accelerated and ejected by the Lorentz force becomes the thrust of the spacecraft. In general, the electro-magnetic thruster has a high thrust and wide range of specific impulse. However, it has not been put to practical use yet because the electrode durability is low performance due to a high current arc discharge. To realize the electro-magnetic thruster with the high electrode durability, the electric thruster which is applied a pseud-spark discharge (PSD) to the plasma generation part, has been developed. The electrode damage is expected to decrease because the PSD is a high current glow discharge rather than arc mode. In this presentation, some performance evaluations of the electro-magnetic thruster applying a PSD will be reported. The electron temperature and density are approximately 5 eV and on the order of 10$^{\mathrm{20}}$ m$^{\mathrm{-3}}$ respectively. The thrust, which is measured by a strain gauge, is up to 150 N and almost proportional to the square of the discharge current. The estimated thrust density and specific thrust are on the orders of 10$^{\mathrm{5}}$ N/m$^{\mathrm{2}}$ and 10$^{\mathrm{4}}$ s. [Preview Abstract] |
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LW1.00088: Fundamental Study for Laser Ablation Plasma Electrostatic Acceleration Kaede Yano, Takato Ogasawara, Ayaka Hamada, Hideyuki Horisawa, Haruo Shindo Laser electric hybrid acceleration system is composed of a solid planar propellant and an accelerating electrode with a single circular hole in a copper plate. Focusing a laser pulse onto the surface of the propellant a laser ablation plasma, or LAP is generated and then supplied into the accelerating channel and accelerated by electrode with the electrostatic field. However, the spatial structure and temporal behavior of LAP are complicated. In addition, to realize higher performance of the propulsion system, it is necessary to apply the electrostatic field appropriately after diagnosing these features in detail. Therefore, in this research, to achieve the optimum electrostatic acceleration, measurement of plasma parameters of LAP was conducted using an emissive probe. In this study, we measured the characteristics of plasma which mainly include plasma space potentials, electron temperatures, electron densities, etc. For the plasma diagnostics, we used emissive probes that are suitable for plasma space potential measurement. From the results, it was shown that the plasma potential and electron temperature rose up to 14 V and 20 eV, respectively, in 30 ms after laser ablation. [Preview Abstract] |
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LW1.00089: Study of plasma thruster using ICRH in sheet plasma Miku Nishimura, Toshikio Takimoto, Akira Tonegawa, Kohnosuke Sato, Kazutaka Kawamura Long-term space missions be required the ability to more widely vary thrust and specific impulse. The thrust and the specific impulse are possible to be freely controlled by the plasma production and the ion heating region are separation. We have developed a newly plasma thruster using ion cyclotron resonance heating (ICRH) in sheet plasma device, TPD-Sheet IV. The sheet plasma is a magnetized thin slab plasma which extends along a uniform static magnetic field, with a certain width, and a very small thickness. Because of these characteristics energetic ions in a sheet plasma, traverse the dense plasma region only momentarily in each cyclotron gyration. The adverse effect of collision on plasma heating by ICRH can be negligibly small, resulting the efficiency of ICRH of the sheet plasma is larger than that of the cylindrical plasma. In this study, we have demonstrated the characteristics of sheet plasma in ICRH. The propellant gas is helium at 1.34e-7 kg/s, DC discharge power is 7 to 15 kW, the stationary magnetic field is \textasciitilde 0.1 T and RF power is \textasciitilde 300 W. Operation at an RF power level of 300W, yields a thruster of 5.9 mN and a specific impulse of 4500 s. [Preview Abstract] |
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LW1.00090: Cross-field electron transport inside an insulating cylinder of a baffled probe Andrew Alt, Yevgeny Raitses Short-circuiting effects in magnetized plasmas by conductive walls, such as the Simon effect [1], have long been observed in laboratory plasmas. In this work, a different short-circuit effect is suggested that is due to bouncing of magnetized electrons off the sheath near confining walls. Experiments have been performed in a magnetized Xe plasma in a cross-field Penning configuration with density \textasciitilde 10$^{\mathrm{12}}$cm$^{\mathrm{-3}}$ and an electron temperature \textasciitilde 2eV [2]. A cylinder with one open end was placed across field lines so that electrons were blocked from reaching a wire recessed behind the shield while ions were unimpeded. This configuration is relevant to the magnetically insulated baffled probe (MIB), a diagnostic for passively measuring plasma potential [3]. However, the measured electron current was much higher than expected even when the wire was recessed several electron gyroradii behind the baffle. The bouncing motion is suggested as a potential cause for the short-circuiting to the bulk plasma and has been studied with numerical approaches and with separate experiments designed to isolate the effect. This work highlights an effect that may be important for cross-field transport near the walls in a variety of other magnetized plasmas. [1] A. Simon, J. Geophys. Res. 75, 6287 (1970). [2] Raitses, et. al., 34th IEPC, Kobe, Japan (2015). [3] Demidov et. al., Rev. Sci. Instrum. 81 10E129 (2010). [Preview Abstract] |
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LW1.00091: Dual RF assisted Pulsed Laser Deposition of Transitional Metal Nitride Thin Films. Heman Bhuyan, Partha Saikia, Miguel Escalona, Mario Favre, Edmundo Wyndham, Julian Schulze, Felipe Veloso Dual radio frequency capacitively coupled plasma assisted pulsed laser deposition (PA-PLD) have the advantage of preventing the micro-particles reaching the substrate during thin film depositions. The plasma DC self-bias activates the substrate surface and destroy the large micro-particles reaching on it. The dual frequency offers the advantage of controlling the ion bombardment energy independently of the ion flux by tuning the low frequency (LF) power. We have compared transition metal nitride thin films such as the titanium nitride (TiN) and tungsten nitride (WN) in the hybrid configuration PAPLD. Optical emission spectroscopy was carried out during deposition. Standard surface science diagnostics like, x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy and atomic force microscopy were used to characterize the deposited thin films. A comparative analysis of the thin films deposited by conventional PLD and PA-PLD, has shown that the PA-PLD technique improves the quality of the deposited films with respect to their stoichiometry, morphology and deposition rate. [Preview Abstract] |
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LW1.00092: Prebreakdown Luminosity Increase In Flames Jackson Pleis, Robert Geiger, Donald Kendrick When an external electric field is applied to the combustion zone electron-neutral collisions can lead to vibrational excitation and ionization at higher electric field strengths. Prebreakdown electric fields are observed to affect the luminosity of the flame. This is accompanied by changes in combustion efficiency, pollutant production, and heat transfer. Luminosity increases rapidly (\textasciitilde 10 ms) and is voluminous. Pulsed voltages shorter than 5 ms do not affect the luminosity. These timescales suggest that an increase in soot production is not the cause. Furthermore, electron impact reactions are also not a likely culprit. An ionic mechanism seems most plausible. At a critical applied voltage, transient breakdown occurs within the flame. Plasma discharges were observed using a high-speed camera. Discharges can occur between hot spots within the flame. These breakdowns occur randomly, due to the turbulent nature of the flame. Certain conditions lead to CO decreases with increases in the corrected NOx (cNOx) while other conditions can produce the opposite result. When breakdown occurs, cNOx increases with little effect on CO. A prebreakdown optimum is observed for minimizing the CO and cNOx emissions. The dominant mechanism is expected to be enhanced mixing due to ion wind effects. [Preview Abstract] |
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LW1.00093: Investigation of plasma dynamics in a packed bed plasma reactor (PBPR) Zaka ul Islam Mujahid, Ahmed Hala Packed bed plasma reactors (PBPR) are very promising for abatement of environmental pollutants and hydrocarbon gas conversion. Several computational studies have extensively investigated the plasma formation in a PBPR, however the exact details about plasma dynamics are still unknown. In this work, we have studied the phase synchronized space and time resolved emission from a packed bed DBD, using an ICCD camera from two different axis i.e. top, through a transparent electrode and the side between the two electrodes. It was found that the plasma dynamics change with the applied voltage and power. The time resolved current shows that in each half cycle of the applied voltage, multiple discharge current pulses can be generated. It was observed that the first current pulse in each half cycle generates a filamentary discharge. The subsequent pulse generates surface ionization waves over the surface. All the following current pulses generate intense plasma at the contact points between the dielectric pellets. The study validates the modeling expectations of the major role of intense electric field at the contact points. [Preview Abstract] |
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LW1.00094: Characterization of cold atmospheric pressure plasma plume in the ambient air for medical applications Veda Prakash Gajula, Kiran Patel, Narayan Behera, Ajai Kumar Over the last few years, many researchers have performed experiments to understand the low temperature atmospheric pressure plasma parameters for medical applications. Still there is a lack of clarity about optimization of the plasma jet parameters for specific medical applications. Possibly this is due to the adopting various experimental conditions. In this work, we have attempted to further understand the plasma plume parameters such as temperature, velocity and electron density, along the plume length. For this a 4kVp-p, 33 kHz sinusoidal voltage source has been developed. Helium as an active gas with flow rates of up to 11 lpm is used to produce the plume length of 4 cm into the ambient air. Thorough characterization of the plume has been carried out by using optical diagnostics such as emission spectra measurements, ICCD imaging and electrical discharge using voltage and current probes. The plasma density along the length of plume has been assessed by using the data obtained from the ICCD images (for plume drift velocity) and plume current measurements. The estimated values are in the range of 0.05-3.2 x 10$^{\mathrm{12}}$ cm$^{\mathrm{-3}}$. Furthermore, the discharge ignition and plasma plume dynamics with gas flow rate will be presented. [Preview Abstract] |
(Author Not Attending)
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LW1.00095: The second type of sharp-front wave mechanism of strong magnetic field diffusion in metal Bo Xiao, Chunhui Yan, Ganghua Wang, Mingxian Kan, Shuchao Duan When a strong magnetic field diffuses into a metal, the metal is ablated by Joule heating companying the magnetic diffusion process, and the metal's resistance changes violently with the fastly growing temperature. If the metal is heated to partially ionized plasmas which has a resisitance that is several orders higher than the resistance of the cold metal, the magnetic diffusion process can be approximately described by the sharp-front diffusion wave theory [1], which gives a simple formulas for describing the velocity of diffusion process. However, if the plasmas escapes immediately by, for example, blowing, the sharp-front diffusion wave theory is no longer applicable because the resistance of the conductor becomes infinity. We would need another type of sharp-front diffusion wave theory (Type II Theory) to describe the magnetic diffusion behaviors in this situation. In Type II Theory, the sharp-front diffusion wave velocity depends on 3 parameters, i.e., the magnetic boundary condition $B_0$, the critial temperature $T_c$, and the cold metal resistance $\eta_s$. The dependence of the velocity on the three parameters is analyzed in details in this presentation. \\[4pt] [1] Bo Xiao, et al, \textit{Physics of Plasmas}, \textbf{23}:082104 (2016) [Preview Abstract] |
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LW1.00096: Generation of reactive oxygen and nitrogen species in cancer and normal cells exposed to atmospheric pressure plasma jets: Selectivity and Effects of the operating parameters. Tae Hun Chung, Sun Ja Kim, Hea Min Joh, Tae Hong Kang Exposure of cold atmospheric plasma to cancer cells increases the cellular levels of reactive oxygen and nitrogen species (RONS), which has been linked to apoptosis and the damage of cellular proteins, and may also indirectly cause structural damage to DNA. We investigated the effects of the operating parameters of plasma jet on the generation of the extracellular and intracellular RONS. Cold plasma-induced differential effects between normal and cancer cells were comparatively examined. Melanoma and normal skin fibroblast cells (counterparts, isolated from the same patient) were used for plasma--cell interactions. The remarkable increase of intracellular reactive oxygen species (ROS, such as nitric oxide (NO), hydroxyl radicals (OH), and hydrogen peroxides (H2O2)) production only occurred in melanoma cancer cells rather than in normal cells. In addition, the effect of additive oxygen gas on the plasma-induced oxidative stress in cancer cells was investigated. It was observed that DNA damage was significantly increased with helium/oxygen plasma compared to with pure helium plasma. [Preview Abstract] |
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LW1.00097: The fully magnetized Fokker-Planck and Balescu-Lenard-Guernsey equations. Ding Li, Chao Dong, Wenlu Zhang In the magnetized and laser fusion plasma, space and astrophysical plasma, the particles' gyro-radii can be smaller than the Debye length when there is a strong magnetic field. This will have a significant influence on collision dynamics and many physical processes such as parallel velocity slowing down, temperature relaxation, particle diffusion, thermal transport, and so on. The fully magnetized Fokker-Planck equation is derived in which collision term includes a uniform magnetic field meanwhile the analytical expressions of magnetized Fokker-Planck coefficients have been derived explicitly within the binary collision model. The fully magnetized Fokker-Planck kinetic equation is also manipulated into the Landau form. The fully magnetized Balescu-Lenard-Guernsey equation is derived in which a uniform magnetic field is included in collision term by employing the Fokker-Planck approach. By using the fluctuating electrostatic field for quiescent plasmas, the magnetized Fokker-Planck coefficients are calculated explicitly based on the wave theory which includes the collective effects in a proper manner. Manipulating the magnetized Fokker-Planck collision term into the Landau form, the magnetized Balescu-Lenard-Guernsey collision term is obtained. [Preview Abstract] |
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LW1.00098: Nanoparticles growth regions in carbon arc: simulations and experiments Alexander Khrabry, Shurik Yatom, Vladislav Vekselman, Igor Kaganovich, Andrei Khodak, Yevgeny Raitses Growth of nanoparticles (NPs) in atmospheric pressure carbon arc in helium was modeled in 2D. Non-equilibrium plasma model was coupled to heat transfer in electrodes and multiple surface physics phenomena, such as radiation, electron emission, ion recombination, space-charge limited sheaths. This allowed accurate prediction of carbon ablation region at the anode surface, carbon transport to colder regions outside the arcing volume where it condenses to form NPs, with their further coagulation [1]. Chemical composition of the plasma gas was computed; good agreement on C$_{\mathrm{2}}$ molecules density profile with results of LIF measurements [2] was obtained. The simulations showed that C$_{\mathrm{2}}$ and C$_{\mathrm{3}}$ molecules are precursors for the formation of NPs. Consumption of carbon gas for the NPs growth is fast, preventing formation of larger carbon molecules. Thermal convection of gas heated by the electrodes affects the shape of NPs growth region, while the role of particle diffusion is small. The shape of the NPs growth region and the NPs sizes simulated were in a good agreement with results of LII measurements [3]. [1] P. Kappler et al., J. Appl. Phys. \textbf{50} (1979), 308. [2] V. Vekselman et al., Plasma Sources Sci. Technol. \textbf{27} (2018) 025008 [3] S. Yatom et al., MRS Comm. (2018) doi:10.1557/mrc.2018.91 [Preview Abstract] |
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LW1.00099: Electron Temperature and Plasma Density in Ar/N2 Admixtured Non-thermal Atmospheric Pressure Plasma Jet Pradoong Suanpoot, Jirapong Sornsakdanuphap, Bhagirath Ghimire, Bhagirath Ghimire, Young June Hong, Guang-Sup Cho, Eun-Ha Choi A model based on plasma propagation velocity has been recently developed to estimate the electron temperature (Te) of non-thermal plasma jets. In this work, we have extended this model to calculate Te for plasma generated with mixed gases (Ar/N2) and the results are compared with pure Ar. Plasma has been generated by input discharge voltage of 3.0 kV at driving frequency of ≈ 40 kHz. A high-speed single-frame intensified charged coupled device (ICCD) has been used to observe the space and time-resolved discharge images and estimate the value of plasma propagation velocity (ug). The value of ug for Ar/N2 admixtures (0-5\%) has been obtained in the range of 104-105 m/s. The electron temperature have been calculated for these mixed gas plasmas. The average electron temperature has been found to be about 1.18 eV for Ar plasma and it increases up to 1.39 eV for plasma with Ar/N2 admixture. Also, the average plasma density has been found to be about 6.61×1014 cm-3 for Ar plasma and it decreases down to 2.74×1014 cm-3 for plasma with Ar/N2 admixture. Our results obtained with modified convective-wave packet model can be a new contribution to plasma medicine. [Preview Abstract] |
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LW1.00100: Discharges in liquids: Experiment and Simulations of plasma kinetics Bill Graham, Leonidas Asimakoulas, Tomo Murakami, Tom Field Plasma discharges in liquids interest researchers and users in areas such as bio-medicine, food safety and agriculture. Here a voltage (~300 V) is applied to a metal electrode in grounded saline to produce a range of chemical and physical phenomena. Our focus is to use experiment and modelling to explore, understand and harness them. This follows some previous work on vapour layer production (Schaper et al P.S.ST. 20, 34004, 2011). Here we use a single-shot ICCD camera alongside a100,000 fps fast framing camera to image the vapour formation and the subsequent discharge characteristics. From these images synced with electrical measurements we have found that the electrical breakdown is due to a vaporization cycle of Joule heating of the electrode and then transfer to the bulk liquid. The electric field values within these time evolving vapour layers are obtained by importing the vapour - liquid boundaries for each frame into a Finite Element software model. This feeds into plasma kinetics and chemistry simulations to predict the space and time evolution of the electric fields. Early results show that at very high gas temperatures (~2000 K) the electron density can have a value of up to 2.1x1011 cm-3. [Preview Abstract] |
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LW1.00101: High Thrust-To-Power Annular ION Engine Status. Michael Patterson, John Foster The NASA-patented Annular Ion Engine (AIE) may be one means of achieving significant advances in performance over state-of-art electric propulsion thruster technologies presently employed in space. In particular, the AIE may enable increases in the thrust-to-power (F/P) ratio. A technology option that can deliver increased F/P ratio is particularly attractive for application to Earth-orbital missions, where minimizing the transfer-time to operational orbit, or rapidly executing maneuvers, may be highly desirable. This work discusses the on-going activities at NASA Glenn Research Center and at University of Michigan to optimize the AIE ion optics and the discharge magnetics designs, to yield a high F/P AIE for Earth-orbital applications. [Preview Abstract] |
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LW1.00102: Plasmas Sustained by High Repetition Rate Nanosecond Pulses: Recombination Mechanisms in Ar with H2O Impurities Vladlen Podolsky, Sergey Macheret Previously, microwave diagnostics was performed for a quasi-steady plasma generated with repetitive nanosecond pulses at several Torr in argon with H2O impurity. In this work, a 0-D kinetic model was developed to understand the recombination between the pulses. The model included electron energy and continuity equations. In pure argon, both the electron temperature relaxation and recombination are very slow. The presence of trace amounts ($<0.1\% $by volume) of H2O drastically changes the mechanisms and rates of recombination and thermalization. Ar+ ions are rapidly converted to H3O+, and the electron losses are primarily due to dissociative recombination with H3O+. The electron thermalization time is drastically reduced due to excitation of rotational and vibrational levels of water molecules. The model agrees well with the experimental data. The results show that generating plasma with high electron density and low time-averaged electron temperature is possible by combining repetitive pulses and controlled addition of molecular species to noble gases. [Preview Abstract] |
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LW1.00103: Capacitively Coupled Discharge in Alpha Mode as a Plasma Varactor Andrey Khomenko, Sergey Macheret Increasingly congested electromagnetic spectrum calls for RF systems to be electronically tunable and reconfigurable. Weakly ionized plasma devices can offer attractive solutions in this application because their properties depend on the electron density and frequency and can thus be electronically controlled. Since the capacitance of a plasma discharge is determined in many cases by the sheath capacitance, controlling the sheath thickness can result in a novel plasma varactor (tunable capacitor). In particular, the sheath thickness in capacitively-coupled RF discharges operating in the alpha regime is inversely proportional to the driving RF frequency. In applications, tuning the sheath thickness by carrying the driving RF frequency (e.g. 10-100 MHz) can be used to control the plasma varactor operating in a different frequency range (e.g. 300 MHz-3 GHz). The proof-of-principle experiments were conducted with parallel-plate electrode geometry in air at 1 Torr with an RF amplifier operating at a constant voltage in a wide range of frequencies, 10-120 MHz. The impedance characteristics and the sheath and plasma parameters were inferred from the current and voltage measurements supplemented with optical imaging. The experimental data confirmed that the sheath thickness is inversely proportional to the driving RF frequency, so that the capacitance is proportional to the frequency. [Preview Abstract] |
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LW1.00104: Investigation on Multiple Plasma Modes in Medium Pressure NF3/He Plasma Soonwook Jung, Soonam Park, Tae Cho, Ken Schatz A plasma mode change in He/NF3 plasma in the medium pressure range ($\le$ 10 Torr) has been investigated both theoretically and experimentally. Pressure often plays an important role in achieving certain process requirements. However, by changing NF3 or RF power in the medium pressure range, we found discontinuous changes in plasma. The mode changes are very similar to well - known $\alpha$ - $\gamma$ transition, based on I-V characteristics and OES diagnostic results. In order to theoretically understand this phenomena in He/NF3 mixture, We used a simple RF breakdown formula with a modification in $\alpha$ and $\eta$ to address the effect of NF3 electron-attachment loss. The theoretical prediction reasonably agrees with the experiments. In sum, this study indicates that the mode transition is related with the modified $\alpha$ to $\gamma$ transition, and suggests that the onset of the mode change can be controlled with external parameters. [Preview Abstract] |
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LW1.00105: Plasma-derived Advanced Oxidation Dose Assessment of Modular Dielectric Barrier Discharge Plasma Reactor Joseph Groele, John Foster The abundant generation of hydroxyl radicals induced via plasma-water interaction is a promising, novel advanced oxidation technology for the treatment of challenging wastewaters that contain recalcitrant and emerging contaminants not removed by conventional wastewater treatment. Although plasma-driven advanced oxidation processes have successfully demonstrated removal of a wide range of contaminants in laboratory-scale reactors, the scale-up to high-throughput processing represents a technology development problem that must be solved to make practical plasma-based water treatment economically feasible. To facilitate scale-up, a modular approach involving multiple dielectric barrier discharge plasma applicators inserted into liquid cross-flow is developed to inject the required advanced oxidation dose for contaminant decomposition. The concentrations of hydrogen peroxide, ozone, and hydroxyl radicals transferred to the liquid as it passes the applicator are measured, and the performance is compared to traditional advanced oxidation processes. [Preview Abstract] |
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LW1.00106: Mesocrystal and the NANOCUBE to Class Action Widastra Hidajatullah, Polycarpus SWANTORO,HE Mr Drs-. Follows Fukunaga -2007 cube model in micromagnetics herewith Fig 8a of ``structural features of self-assembled arrays of iron oxide \textbf{NANOCUBES }depict in Bergstroem: \textbf{Mesocrystals in Biominerals {\&} Colloidal Arrays''- }\underline {Acc.Chem.Res, } 2015 Shiaki-Hyodo confirm of meso-scale fusion . For Denis Gebauer \textbf{``Non-Classical Crystallisation {\&} Mesocrystals'' } also provide Borgonovi {\&} Guarneri: \textbf{``Fractal vs Qauasi Classical Diffusive Transport in a class Qauantmu Systems''} Aug 1995 as well as ``transformation of information between the quantum {\&} classical pictures''. Aobe all we sought ``\textit{if they win the case''}in \underline {https://en.wikipedia.org/wiki/Class\textunderscore action} sociophysics {\&} econophyscis dealt with. [Preview Abstract] |
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LW1.00107: Nanoindentation Between Isomorphicity to Displacement through Attractor MayBe Anastasia Praditha Adelina, Widastra Hidajatullah Took the furthers of ``constricted loop'' from Lanci {\&} Kent-2003 we compare ``generic Stoner-Wohlfarth particle'' with ``generic stable deformation'' provided by Mayr involves gauge theory as \textbf{``A Room Temperature Molecular/Organic-based Magnet''}-1991. Defined by \textbf{nanoindentaion'' }dealt with ``load displacement measurement'' we sought ``anisotropic elastic moduli ever inspected of ``isomorphicity of these moduli spaces for general G'' --\textit{ibid}-h 11 coincides such as the moduli of elliptic curves depict in genericSW. Describes if we appreciates biomolecular electronics'' i.e. we adopt autocatalyst as the ability of certain chemicals to enhance we offers for Engel elasticity `` as well as \textit{constant elasticity of substitution''-}Hollis Chenery- so ``anisotropy distribution is extentively \underline {\textbf{iterated }}to fig 5a from Elwenspoek whereas the fig 5b of ``strange attractor'' for ``the attractor maybe a point, a line or a fractal''/Paul Davies-1992. [Preview Abstract] |
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LW1.00108: 20Calcium-bearing of Fluorapatite & Nannofossils, between MESOFRACTALS and Nanocubes Widastra Hidajatullah,SSi From Sendhil Kumar,et.al provided nanomaterials to polymer expatiaition inherentedly to RE-Expiate as well as calcareous nannofosils and fluorapatite have similar properties in 20-Ca bearing. To 187 imply of nanocubes herewith MESOFRACTALS: denotes cartoons whose generator intervals fall into two non-empty classes:(i). diagonal intervals sharing a unique H satisfying 0 |
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LW1.00109: Quantum Fractals to Kneading Sequences Anastasia Praditha Adelina,SE, Irene Prastiyani,SS Those were ``function transformation {\&} Mandelbrot set'' described in Bonanno's ``kneading sequences'' to ``when the $\Phi $q$_{\mathrm{\thinspace \thinspace }}$transformation is \textbf{iterated }`` from Arkadius Jadczyk 2006's \textbf{``Quantum Fractals, Geometric Modeling of Quantum Jumps into Conformat Maps'' }further sought Lapidus, \textit{et.al }:\textbf{''Fractal Strings {\&} Multifractal zeta functions'' }-- 2009 . To explains ``fluxions'' from Isaac Newton [ 1642 -- 1727 ] in The Riemann Integral we ussually dealt with Riemann zeta function fro Catherine Zeta- Jones retrieved by HE. Mr. Prof. THE HOUW LIONG,PhD fom Prodi of Physics ITB. FORMAPPI[Forum Masyarakat Peduli Parlemen INDONESIA ] evovles through \textbf{``Dynamics of Continued Fractions {\&} Kneading Sequences of unimodal MAPS''} instead excerpts bifurcation etc... [Preview Abstract] |
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LW1.00110: Neutrosophic Permittivity Florentin Smarandache Neutrosophic Permittivity is the (t$_{\mathrm{P}}$, i$_{\mathrm{P}}$, f$_{\mathrm{P}})$-neutrosophic degree to which a medium resists an electric charge flow, where: t$_{\mathrm{P}} \quad =$ degree of permittivity; i$_{\mathrm{P}} \quad =$ degree of indeterminate-permittivity; and f$_{\mathrm{P}} \quad =$ degree of unpermittivity. We prove several theorems related to Neutrosophic Permittivity. [Preview Abstract] |
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LW1.00111: A Ku band Relativistic Magnetron Driven by a PFN-Marx Generator WEI LI, Tao Xun, Han-Wu Yang, Jun Zhang A Ku band Relativistic Magnetron Driven by a PFN-Marx Generator is proposed in this paper. The relativistic magnetron has 18-resonant cavities and a diffraction output configuration. The radiation parameters are that the central frequency of 14.4GHz, microwave power of 400MW, pulse duration of 50ns, far-field pattern of TE01. The PFN-Marx generator, which can produce 400kV of voltage and 4GW of electric power, is composed of multi-level ceramic capacitors and copper wire inductances. A triggered cascade gas switch is employed in the generator for discharging to the relativistic magnetron. [Preview Abstract] |
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LW1.00112: Characterization of the flashover plasma across a ceramic-vacuum interface in a high-power microwave tube Tao Xun Driven by a negative high voltage pulse (-500 kV, 150 ns), the flashover plasma luminescence process and its spectrum characteristics were observed by high-speed framing camera and specter. A brighter and faster luminescence process with an expansion velocity of 2×10\textasciicircum 8 cm/s.The radial and angular expansion velocity components were analyzed and got respectively. A higher average electron temperature of 4.57 eV was obtained from the spectrum results. Particle-in-cell simulation results of electron multiplication process and their movement along the ceramic surface with different primary electron emission modes agreed with the experimental observations. All these results indicate that since the explosive emission provides more energy than field emission and causes stronger secondary avalanche and gas ionization processes, the surface flashover initiated with explosive electron emission can occur much easier and develop faster. This work can give a reference for evaluation and design of ceramic vacuum interfaces for high-current applications. [Preview Abstract] |
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LW1.00113: A repetitive high current e-beam accelerator based on spark gap switch and liquid forming line Hanwu Yang, Zicheng Zhang, Jingming Gao, Tao Xun, Song Li Studies of a multi-gigawatt high power microwave (HPM) tube require an e-beam accelerator in the tens gigawatt GW level. Such a repetitive accelerator is built and it has a Tesla transformer (TT) and a helical liquid insulated forming line (PFL). The primary capacitor of the transformer is charged by a constant-current high voltage power supply of 120 kJ/s. The TT is an open-core autotransformer, with coupling coefficient greater than 0.9 and output voltage up to 1.2 MV. The co-axial forming line is insulated with water-ethanol mixture, to achieve an optimum dielectric constant and line impedance. The forming line is switched by to the transmission line by a SF$_{\mathrm{6}}$ gas switch. The transmission line is used to further increase the HPM load voltage. A ceramic interface is used for improving vacuum level. The accelerator operates well with 5 Hz repetition, 80 ns FWHM and about 30 GW peak power. [Preview Abstract] |
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LW1.00114: Role of keV electrons in atmospheric pressure transient nanosecond-pulsed plasmas Sanjana Kerketta, Martin Gundersen Nanosecond pulsed plasmas have demonstrated high energy efficiencies and low energy costs for applications including the treatment of combustion exhaust and plasma assisted ignition. The reason behind this increased effectiveness is not well understood due to incomplete knowledge of electron-molecule dynamics at microscopic scales and during sub-nanosecond time intervals. We hypothesize that the presence of high energy electrons (\textgreater keV) for a brief time (nanoseconds) is one of the probable reasons for the high radical populations which can lead to different combustion chemistry. A mechanism involving thermo-field emission processes from surface macro and micro irregularities is considered for the generation of keV electrons. A simulation code employing Monte Carlo collision algorithm is developed to compare differences in electron trajectories and radical populations in the gas medium. It is concluded that high energy electrons alter radical production rates significantly and deserve study for understanding of the high efficiencies observed in transient plasma applications. [Preview Abstract] |
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LW1.00115: Simultaneous Control of Multiple Resistive Wall Modes on the DIII-D Tokamak Alexander Battey, Jeremy Hanson, Jim Bialek, Gerald Navratil Resistive wall modes (RWM) with toroidal mode number greater than one have been observed on the DIII-D tokamak following the successful stabilization of the n$=$1 mode. This implies a need to understand the role of multiple unstable modes on RWM control as well as a strategy for multiple mode control. We have simulated successful, simultaneous control of n$=$1 and n$=$2 RWMs on DIII-D using the VALEN code. It has also been shown that modes may couple through induced currents in the vessel wall. This coupling can affect both the growth and rotation of both stable and unstable modes, but is small enough so that each mode can be approximated as independent of one another. This allows each RWM to be controlled through independent feedback relationships. Several multi-mode feedback strategies are presented and their ability to raise the normalized beta limit is discussed. [Preview Abstract] |
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LW1.00116: Invoices, Values {\&} Votes of IVP/Veritas, Probitas, Iustitia Jakob Oetama, Dr-HC Furtherances of $\Psi (x$, 0) $=$ 2 [ 1 $+ \quad e^{-\alpha x}$] of wave-function generates from IVP-InitialValueProblem, Hans J. Wospakrik {\&} Freddy P. Zen: \textbf{``Inhomogeneous Burgers Equatio and the Feynman-Kac path Integral''-}Dec 15, 1998 we have retrieves \underline {https://doi.org/10.1137/0505061} as well as \textit{d/dx[}ln (1 $+ \quad e^{x}$ )$] =$ [ 1 $+$ ($e^{-x\thinspace } \quad +$ 1)] quotes in realms of Fermi-Dirac statistics by A.Purwanto,PhD:''\textbf{Fisika Statistik `` }, h 188. Firmly, about \textit{initial value problem/IVP }also sought in Thierry Goudon,\textit{et.al}-2004 h 1530/1549 instead from Wospakrik,Zen-98. ``spalled'' reaction produces high energy secondary particles (neutrons, protons, mesons, gamma ) of synergistic from Dr. Nadia Fomin we have at least OSC/OpenSetCondition for the Topology of $R $-- Bartle {\&} Sherbert: \textbf{``Introduction to Real Analysis''- }1991- h 346 denotes we provides MSMock:\textbf{''An Initial Value Problem for Semiconductors Device Theory''}-1974 we vote [in]-Voices Recognitions of E-Voting Machine from Dr. Maman BUDIMAN/Prodi of Physics ITB. To adopts \textbf{pro deo }attorney {\&} \textbf{pro bono }legal aids public goods. PC Gration `s \textbf{gratis }not always profites.. [Preview Abstract] |
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LW1.00117: Refined Neutrosophic Memory Florentin Smarandache According to Sigmund Freud, memory is divided into three parts: conscious, preconscious, and unconscious. We reorganize and extend this division by adding the neutral/indeterminate part, that we call ``aconscious'', which is neither conscious nor unconscious, but a blend of both. Memory is thus divided into three main parts. It is a symmetric triad of the form (\textless A\textgreater , \textless neutA\textgreater , \textless antiA\textgreater ) as in neutrosophy: 1) Conscious, meaning things that we are currently aware of. (It corresponds to \textless A\textgreater .) 2) Unconscious, which comprises things that we are not aware of; they are hard to access because they are deep inside our mind. It is the opposite of conscious. (It corresponds to \textless antiA\textgreater .) 3) Aconscious. We coin the concept of ``aconscious'' (adj.), which means: away from conscious and unconscious, or neither conscious nor unconscious, but in between, or a mixture of conscious and unconscious -- a vague buffer zone between them. The consciousness, aconsciousness, and unconsciousness are the sources of positive, neutral (or blended), and negative emotions, thoughts, and behaviors throughout our lifespan. [Preview Abstract] |
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LW1.00118: Physical Plithogenic Set Florentin Smarandache Let $U$ be a universe of discourse. A Plithogenic Set is a set $P$ included in $U$, such that each element $x$ in \quad $P$ is characterized by one or more attributes $\alpha_{\mathrm{1}}$, $\alpha_{\mathrm{2}}$, \textellipsis , $\alpha_{\mathrm{m}}$, and each attribute $\alpha_{i\thinspace }$has many values. The element $x$ is characterized by all attributes' values: $V =$\textit{ \textbraceleft v}$_{1}, v_{2}$\textit{, \textellipsis , v}$_{n}$\textit{\textbraceright . } Each attributes value $v $ in $V$ has a corresponding \textit{degree of appurtenance d(x, v)} of the element $x,$ to the set $P$, with respect to some given criteria. For each attribute $\alpha_{i\thinspace }$there is a \textit{dominant (most important) attribute value}, and one computes the \textit{contradiction degree} function between any attribute values $v $and its corresponding dominant attribute value $v_{D}$, \quad denoted by $c(v_{D}, v).$ Plithogenic aggregation operators are further constructed for practical applications. [Preview Abstract] |
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