Bulletin of the American Physical Society
65th Annual Gaseous Electronics Conference
Volume 57, Number 8
Monday–Friday, October 22–26, 2012; Austin, Texas
Session NW1: Poster Session I (7:00-9:30PM) |
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Room: Salon CDE |
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NW1.00001: ATOMIC AND MOLECULAR PROCESSES |
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NW1.00002: Comparison of spherical and spheroidal expansions for energies and oscillator strengths of H\(_2^+\) Jeremy Savage, Dmitry Fursa, Mark Zammit, Igor Bray We calculate the bound state energies and oscillator strengths of the hydrogen molecule ion using configuration interaction expansions in both spherical and prolate spheroidal coordinates. States were built from similar Laguerre bases in the fixed nuclei approximation, allowing for the direct comparison of convergence rates and accuracy. Such a comparison will demonstrate the relative usefulness of spherical and spheroidal expansions for scattering on diatomic molecules. Specifically, this will assist in the implementation of the convergent close-coupling approach to scattering which is optimised by a smaller, more efficient set of configurations. It will be shown that the spheroidal basis is significantly faster to converge and more accurate for the low-lying states but this advantage gradually dissipates as state energy increases and the orbitals become more spherical. [Preview Abstract] |
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NW1.00003: Electron Scattering from Pyrazine compared with Pyrimidine and Benzene P.D. Palihawadana, J.P. Sullivan, S.J. Buckman, M.J. Brunger, C. Winstead, V. McKoy, G. Garcia, F. Blanco Pyrazine (C$_{4}$H$_{4}$N$_{2})$ is a model molecule for studying electron interactions with nucleases. Also pyrazine is an ideal target, due to its high symmetry ($D_{2h})$, for theoreticians to investigate electron collisions with complex DNA/RNA bases. In this work we present absolute elastic differential cross sections and elastic excitation functions for scattering of low-energy electrons by pyrazine measured using a crossed electron-target beam apparatus at the Australian National University. A comparison is also made between pyrazine cross sections with previously measured pyrimidine and benzene cross sections. Since all those molecules are similar in structure and considered as analogues to nucleobases, we intend to discuss similarities and differences in electron scattering results between three molecules. [Preview Abstract] |
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NW1.00004: Comparison of ion-molecule reactions in cyclohexane, methylcyclohexane and ethylcyclohexane Charles Jiao, Steven Adams Cyclohexanes including cyclohexane (C$_{6}$H$_{12})$, methylcyclohexane (C$_{7}$H$_{14})$ and ethylcyclohexane (C$_{8}$H$_{16})$ are significant components of many practical fuels. C$_{6}$H$_{12}$ and C$_{7}$H$_{14}$ have been chosen as representative cycloalkanes in several proposed surrogate mixtures for jet fuels. In this study, the gas-phase ion-molecule reactions in these three cyclohexanes are examined, and comparison of the reaction channels in each of the cyclohexanes are made. A variety of reaction channels has been observed, which include charge transfer, H$^{-}$ transfer, H$_{2}^{-}$ transfer, H$_{3}^{-}$ transfer, hydrocarbon anion transfer, and association with concerted fragmentation. Among these channels, H$^{-}$ transfer is the most prevalent in the three cyclohexanes and, for many reactant ions, is the exclusive channel. Also observed is that H$_{3}^{-}$ transfer occurs only in C$_{6}$H$_{12}$ while C$_{3}$H$_{7}^{-}$ transfer occurs only in C$_{8}$H$_{16}$. [Preview Abstract] |
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NW1.00005: Electron Impact Excitation and Ionization of Neon Oleg Zatsarinny, Klaus Bartschat We have further developed the $B$-Spline $R$-matrix (BSR) code~[1] to allow for a large number of pseudo-states in the close-coupling expansion. In the present work, the BSRMPS approach~[2] was employed to perform semi-relativistic (Breit-Pauli) close-coupling calculations for elastic scattering, excitation, and ionization of neon from both the ground state and the metastable excited states. Coupling to the ionization continuum through the pseudo-states is important for low-energy elastic scattering (to represent polarizability effects), for excitation in the ``intermediate'' energy regime of about 1-5 times the ionization potential, and to allow for the calculation of ionization processes by transforming the results obtained for excitation of the positive-energy pseudo-states. The current results represent a significant extension of our earlier near-threshold work~[3] and previous non-relativistic RMPS calculations~[4,5].\\[4pt] [1] O.~Zatsarinny, Comp. Phys. Commun.~{\bf 174} (2006) 273.\\[0pt] [2] O.~Zatsarinny and K.~Bartschat, Phys.~Rev.~Lett.~{\bf 107} (2011) 023203.\\[0pt] [3] O.~Zatsarinny and K.~Bartschat, J.~Phys.~B~{\bf 37} (2004) 2173.\\[0pt] [4] C.~P.~Ballance and D.~C.~Griffin, J.~Phys.~B~{\bf 37} (2004) 2943.\\[0pt] [5] C.~P.~Ballance {\it et al.}, J.~Phys.~B~{\bf 37} (2004) 4779. [Preview Abstract] |
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NW1.00006: Relativistic convergent close-coupling calculation of the spin polarization of electrons scattered from indium Christopher Bostock, Dmitry Fursa, Igor Bray The measurements of the spin asymmetry parameter (Sherman function) for elastic and inelastic electron-indium scattering by Bartsch {\em et al.} [J.~Phys.~B 25(1992)1511 are compared with corresponding relativistic convergent close-coupling calculations. The RCCC results provide the first theoretical data to span the full range of energies (1-14~eV) and transitions measured by Bartsch {em et al.}. The spin asymmetry parameter is presented for $(5p)^2P^o_{1/2}~\rightarrow~(5p)^2P^o_{1/2}$ elastic scattering, $(5p)^2P^o_{1/2}~\rightarrow~(5p)^2P^o_{3/2}$, $(5p)^2P^o_{1/2}~\rightarrow~(6s)^2S_{1/2}$, and $(5p)^2P^o_{3/2}~\rightarrow~(6s)^2S_{1/2}$ inelastic transitions. There is very good agreement between theory and experiment for the elastic spin asymmetries. Some discrepancies still exist between theory and experiment for excited state spin asymmetries. [Preview Abstract] |
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NW1.00007: Electronic excitation of methanol by low energy electrons Joshua Tanner, Leigh Hargreaves, Murtadha Khakoo Measurement of absolute differential and integral cross sections for the lowest lying electronically excited states of methanol will be presented. These cross sections were measured using a crossed electron gas beam spectrometer incorporating a moveable gas beam. The data were normalized against the elastic scattering signal, with the elastic cross sections previously determined in our laboratory [1] using the relative flow method with an aperture-type gas collimator [2]. These data are, to the best of the author's knowledge, the first reported study of these cross sections and have important implications for dosimetry modeling of radiation therapy. \\[4pt] [1] M.A. Khakoo \textit{et al.}, \textit{Phys. Rev. A}, \textbf{77}, 042705 (2008)\\[0pt] [2] M.A. Khakoo \textit{et al.}, \textit{J. Phys. B: At. Mol Phys.}, \textbf{40}, 3601 (2007) [Preview Abstract] |
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NW1.00008: ABSTRACT WITHDRAWN |
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NW1.00009: Generalized Hyperspherical Sturmian functions applied to three-body ionization problems Lorenzo Ugo Ancarani, Dario M. Mitnik, Gustavo Gasaneo Very recently we introduced a methodology to solve three-body break-up problems based on hyperspherical Generalized Sturmian Functions (HGSF) [1]. The use of hyperspherical coordinates makes easier and more natural the incorporation of Peterkop's asymptotic behavior for ionization processes. This technique is an extension of the Generalized Sturmian method implemented before in spherical coordinates [2]. In this report we address different issues involved in the study of single and double ionization of atoms by electron impact, in particular with respect to the so called (e,2e) and (e,3e) processes. For example, we analyze the physical characteristics of different spatial regions of the scattering wave function and the extraction of transition amplitudes. \\[4pt] [1] G. Gasaneo and L. U. Ancarani, J. Phys. A \textbf{45}, 045304 (2012).\\[0pt] [2] A. L. Frapiccini, J. M. Randazzo, G. Gasaneo and F. D. Colavecchia, J. Phys. B \textbf{43} 101001 (2010). [Preview Abstract] |
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NW1.00010: Low energy studies (e,2e) studies from Ammonia (NH$_{3})$ Hari Chaluvadi, Don Madison, K.L. Nixon, Andrew J. Murray, Chuangang Ning, James Colgan Experimental and theoretical Triply Differential Cross Sections (TDCS) will be presented for electron-impact ionization of Ammonia (NH$_{3})$ for highest occupied molecular orbital (HOMO), next highest occupied molecular orbital (NHOMO) and next next highest occupied molecular orbital (N$^{2}$HOMO). M3DW (molecular 3-body distorted wave) results will be compared with experiment for coplanar geometry. The final state electron energies and observation angles are symmetric. [Preview Abstract] |
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NW1.00011: High Energy Proton-Impact Single Electron Capture from Helium K. Morrison, A.L. Harris In single electron capture, the incident proton collides with a helium atom, captures an electron, and leaves the collision as a neutral hydrogen atom. This process has been studied experimentally and theoretically for decades, but recent advancements in experimental technology now allow for more accurate and detailed measurements. Experimental fully differential cross sections are now available for high projectile energies and large scattering angles, and there is a newly-seen peak at the large scattering angles. We will present results from a fully quantum mechanical 4-body model and compare with experiment. [Preview Abstract] |
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NW1.00012: Experimental measurement of plasma parameters and electron energy distribution in ferrite-core side type Ar/He inductively coupled plasma Duksun Han, Jin-Young Bang, Hyo-Chang Lee, Chin-Wook Chung Spatial distributions of a plasma density and an effective electron temperature (Teff) were studied from the measurement of an electron energy probability function (EEPF) in the side type ferrite-core inductively coupled plasma with an argon-helium mixture. As the helium gas was diluted at the fixed total gas pressure of 5 mTorr in an argon discharge, the distribution of the plasma density was changed from a concave to a flat, and finally became a convex, while all spatial profiles of Teff were the hollow shapes with the helium dilution. This evolution of the plasma uniformity with the helium gas could be explained by the increased energy relaxation length and the changed plasma potential, indicating the transition of the electron kinetics from the local to non-local kinetics. From this result, it is expected that the addition of helium gas could be applied as a method to control the plasma uniformity in a large area plasma processing. [Preview Abstract] |
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NW1.00013: Spatial plasma potentials and electron energy distributions in inductively and capacitively coupled plasmas under a weakly collisional and nonlocal electron kinetic regime Hyo-Chang Lee, Chin-Wook Chung Spatial profiles of the plasma potential and electron energy distribution function (EEDF) were measured in inductively and capacitively coupled plasmas (ICP and CCP) under weakly collisional and nonlocal electron kinetic regimes [1]. The measured EEDF at the discharge center was a bi-Maxwellain distribution with low (T$_{1})$ and high (T$_{2})$ electron temperature groups at both the ICP and the CCP, while the EEDF at the radial boundary was closely Maxwellian distribution in the ICP due to cutting of the low energy electrons by relatively large ambipolar potential in this discharge regime. The ambipolar potential in the entire radial region was in the scale of T$_{eff}$ -1.5 T$_{eff}$, where T$_{eff}$ is the effective electron temperature. At the boundary region with the ion mean free path scale, the ambipolar potential increased abruptly and was about T$_{eff,edge}$/2, where the Teff,edge is the effective electron temperature at the boundary, which corresponds to the presheath scale. These results of the ICP, which are contrary to the ambipolar potential of the CCP in a nearly free-fall regime [2], are caused by relatively high T$_{1}$ and a small portion of low energy electron group density to total electron density in the ICP under the weakly collisional and nonlocal electron kinetic regimes. \\[4pt] [1] H. C. Lee and C. W. Chung, Phys. Plasmas \textbf{19} 033514 (2012).\\[0pt] [2] V. A. Godyak, V. P. Meytlis, and H. R. Strauss, IEEE Trans. Plasma Sci. \textbf{23} 728 (1995). [Preview Abstract] |
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NW1.00014: Momentum transfer cross sections for the heavy noble gases A.D. Stauffer, R.P. McEachran We have used our relativistic optical potential method [1] to calculate the momentum transfer cross sections for Ar, Kr and Xe from threshold to 1000 eV. The target ground state as well as the open excited and ionization channels used in the optical potential have been calculated using the MCDF program [2]. We have included 17 excitation channels for Ar, 26 for Kr and 15 for Xe. In the ionization channels, ionization of the outer p, s and d shells were included for Kr and Xe while for Ar all electrons were allowed to be ionized. Comparisons with previous calculations and experimental measurements will be included. We also include analytic fits to our cross sections to aid in plasma modelling studies. \\[4pt] [1] S. Chen, R. P. McEachran and A. D. Stauffer, J. Phys. B \textbf{41} 025201 (2008) \\[0pt] [2] I. P. Grant, B. J. McKenzie, P. H. Norrington, D. F. Mayers and N. C. Pyper, Comput. Phys. Commun. \textbf{21} 207 (1980) [Preview Abstract] |
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NW1.00015: Positron scattering off the H$_{2}^{+}$ and H$_{2}$ molecules using the convergent close-coupling method Mark Zammit, Jeremy Savage, Dmitry Fursa, Igor Bray We have extended a single center formulation of the convergent close-coupling (CCC) method for modeling positron-atom collisions [1] to positron scattering from diatomic molecules. CCC calculations have been applied to positron scattering off the H$_{2}^{+}$ and H$_{2}$ molecules. A single center approach to the calculation of molecular structure was utilised by diagonalizing the target Hamiltonian in a large Sturmian (Laguerre) basis. Such expansions allow us to model positronium formation channels indirectly. A fixed nuclei formulation was used to obtain electronic excitation and total cross sections, which are compared with available experimental and theoretical data. In the near future we will generalize this work to electron and photon scattering off molecules.\\[4pt] [1] D. V. Fursa and I. Bray, New J. Phys., 14 (2012) 035002. [Preview Abstract] |
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NW1.00016: Positron Reaction Microscope Dennis Mueller, Simon Armitage, Corbin Vermet, Chistopher Lee, Alexander Dorn, Stephen Buckman, James Sullivan We are developing a positron reaction microscope to measure kinematically complete ionization reactions of atoms and dissociative ionization of simple molecules by positron impact. The experiment is designed to use the slow positron beamline at the ARC Centre for Antimatter Matter Studies (CAMS) node at the Australian National University (ANU). This project is a collaboration among the University of North Texas, CAMS, and the Max Planck Insitute for Kern Phyzik in Heidelberg. Initial measurements and apparatus calibration will be performed using electrons. For positron measurements, the apparatus will be rolled into position on the slow positron beamline at the CAMS site at ANU. [Preview Abstract] |
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NW1.00017: Positron scattering from helium Roisin Boadle, Joshua Machacek, Emma Anderson, Peter Caradonna, Casten Makochekanwa, Adric Jones, James Sullivan, Stephen Buckman We present new measurements of positron scattering cross sections for helium, including total scattering, total elastic and total inelastic cross sections, which have been extended up to energies of 180eV. We also present a range of low energy elastic differential cross sections. The measurements were performed using our high-resolution, Surko trap-based positron beamline with a typical energy resolution of $\sim $50meV. Comparisons will be made with previous experimental results and with up to date theoretical predictions. [Preview Abstract] |
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NW1.00018: Low Energy Positron Scattering from Molecular Hydrogen Emma Anderson, Roisin Boadle, Joshua Machacek, Casten Makochekanwa, Dennis Mueller, James Sullivan, Stephen Buckman As the simplest homonuclear diatomic molecule, molecular hydrogen is an attractive target for fundamental measurements of positron interactions, and comparisons of these measurements with the best contemporary scattering theory. Using a low-energy, high-resolution positron beam, measurements have been taken of positron scattering from molecular hydrogen between 1 and 200 eV. Total scattering, total elastic scattering, and positronium formation cross sections will be presented, as will as a range of elastic differential cross sections. Comparisons will be made with previous positron and electron scattering measurements and theoretical calculations. [Preview Abstract] |
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NW1.00019: Positron scattering from tetrahydrofuran M.J. Brunger, L. Chiari, W. Tattersall, E. Anderson, J. Machacek, C. Makochekanwa, J. Sullivan, S.J. Buckman We present recent experimental results for positron scattering from tetrahydrofuran. Being a model for the deoxyribose sugar rings in the nucleic acids backbone, tetrahydrofuran is of particular interest for investigating radiation damage in biomolecular systems. The measurements on this species were carried out using the atomic and molecular trap-based positron beamline at The Australian National University with an energy resolution of $\sim $60 meV. Total cross sections and integral cross sections for the positronium formation, elastic and inelastic (direct ionization and electronic excitation) scattering channels are presented over the energy range of 1-190 eV. Low-energy elastic differential cross sections are also presented at selected energies between 1 eV and 25 eV. A fairly good agreement is found with the total cross section results from the only existing previous experimental investigation on this target species by the Trento group. [Preview Abstract] |
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NW1.00020: Low Energy Elastic Electron Scattering from Acetaldehyde Alexsander Gauf, George Balch, Christopher Navarro, Leigh R. Hargreaves, Murtadha A. Khakoo, Carl Winstead, Vincent McKoy We report experimental and theoretical (Schwinger Multi-Channel method, with polarization effects) for electron scattering from acetaldehyde. The incident energies range from 1eV to 30eV and scattering angles from 10 to 130$^{\circ}$. The experimental method used a moveable aperture source with the relative flow method. Comparisons between theory and experiment will be presented. [Preview Abstract] |
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NW1.00021: PLASMA APPLICATIONS |
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NW1.00022: Method to reduce particles and defects on unprocessed wafers caused by clusterization and cross contamination from processed wafers Sanket Sant One of the leading problems in the semiconductor industry with device scaling is defects and particles. Of this the most important ones are particles that can clusterize (condensate) with exposure to atmosphere. These clusters can be formed by residual halides or halide structures on the wafer surface reacting with surface moisture which is unavoidable. Such clusters can prove detrimental to the processed wafer, but more interestingly can migrate inside the FOUP onto unetched wafers. This migration of clusters can cause micro masking and other defects when these wafers are processed. This reduces the wafer yield and is challenging to resolve as we move towards smaller nodes. In this work, different methods of eliminating cross condensation defects and avoiding cluster formation on processed wafers are discussed. UV, Ozone and heat are the primary candidates explored and the mechanism behind each method is explored and optimized. Impact of each mechanism on wafer yield, part corrosion in a reactor platform and wafer throughput has been studied. [Preview Abstract] |
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NW1.00023: Plasma-liquid system with rotational gliding arc with liquid electrode Oleg Nedybaliuk, Valeriy Chernyak, Eugene Martysh, Natalia Belenok, Tamara Lisitchenko Atmospheric pressure plasmas can be created by various types of discharges: transverse arc; discharge in gas channel with liquid wall and others. But most of them aren't sufficiently stable. Stabilization of discharge in the high pressure powerful plasmatron is attained by vortex flow of gas. In the low-powered high pressure discharges the reverse vortex flow ``tornado'' type can be used for the space stabilization. The voltage-current characteristics of discharge at the different regimes are measured. Typical emission spectra of plasma in plasma-liquid system with rotational gliding arc were measured. The population temperatures of excited electronic, vibrational, rotational levels and the flame temperature are determined. [Preview Abstract] |
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NW1.00024: Amplification of femtosecond vacuum ultraviolet laser pulses at 126 nm in an optical-field-induced ionized argon plasma Shoichi Kubodera, Masanori Kaku, Masahito Katto, Kenzo Miyazaki Short-wavelength lasers in the vacuum ultraviolet (VUV) spectral region between 100 and 200 nm have not yet been developed to the same degree as visible and infrared lasers. We have been developing the argon excimer laser at 126 nm by using an optical-field-induced ionized (OFI) argon plasma. We have observed the gain of 0.86 /cm at 126 nm in the OFI Ar plasma, which was produced inside a hollow fiber with a diameter of 250 microns and a length of 5 cm. In this paper, we have used the OFI plasma gain medium as an amplifier of the 126 nm radiation. A femtosecond 126 nm pulse was produced by the seventh-order nonlinear wavelength conversion of a femtosecond Ti:sapphire laser at 882 nm. The femtosecond wavelength-converted coherent VUV beam was then injected inside the OFI plasma that was produced by the same Ti:sapphire laser, resulting in a 2.4-fold increase of the VUV intensity with one-pass amplification. The gain-length product of 0.87 with the one-pass amplification was evaluated, which was consistent with the value we have observed in the previous measurements. The further extension of the OFI plasma by using a hollow fiber would be plausible to increase the gain-length product and the VUV amplified intensity. [Preview Abstract] |
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NW1.00025: Modelling of microwave-driven micro-plasmas in HCPCF L.L. Alves, O. Leroy, C. Boisse-Laporte, P. Leprince, B. Debord, F. Gerome, R. Jamier, F. Benabid New UV sources based on microwave-driven micro-plasmas filling a Hollow-Core Photonic Crystal Fibre (HCPCF) [1], exhibit an unprecedented compactness, flexibility, low-cost and high conversion efficiency. The micro-plasma ($>$10$^{14}$ cm$^{-3}$ electron density, estimated by electromagnetic calculations) is produced by a surface-wave discharge (2.45 GHz frequency) in argon, at 1000-1400 K gas temperatures (measured by OES diagnostics). Our first approach to simulate this system replaces the cladding structure of the fibre (air-holes region) by a capillary cylindrical quartz tube. Simulations use a one-dimensional (radial) stationary model that solves the fluid transport equations for electrons and positive ions, the electron mean energy transport equations, Poisson's and Maxwell's equations for the fields and the gas energy balance equation, coupled to the electron Boltzmann equation for the calculation of the relevant electron parameters [2,3]. We analyze the modification of the plasma with changes in the work conditions, presenting simulations for various HCPCF core radii (50--500 $\mu $m) and electron densities (1--5x10$^{14}$ cm$^{-3})$, at 1mbar pressure. [1] B. Debord et al, ECOC conference Mo.2.LeCervin.5. (2011) [2] L.L. Alves et al, Phys. Rev. E 79, 016403 (2009) [3] J. Greg\'{o}rio et al, Plasma Sources Sci. Technol. 21, 015013 (2012) [Preview Abstract] |
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NW1.00026: ABSTRACT WITHDRAWN |
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NW1.00027: Interconnection resistance improvement by plasma treatment after etching the contact hole Nam-Gun Kim, Sung-Il Cho, Yoon-Jae Kim, Chan-Min Lee, Ji-Hee Kim, Cheol-Kyu Lee, Seok-Woo Nam As the feature size diminished, it becomes important to control the interconnect resistance, especially, on the interface. Conventionally CF$_{4}$ based plasma and HF treatment have been used to remove damaged layer induced during etching the contact holes. However, these methods were limited due to contact enlargement or increment of recess depth. We developed the new treatment to improve contact resistance using H$_{2}$/N$_{2}$ plasma. The H$_{2}$/N$_{2}$ plasma assisted treatment (HAT) after etching contact holes improve the cell current 4{\%} compared with the conventional method. Based on the XPS (X-ray Photoelectron Spectroscopy) and OES (Optical Emission Spectroscopy) analysis, it was found that HAT effectively removed the SiC layer. The atomic concentration of carbon on the surface decreases from 22.3{\%} to 1.5{\%} on the XPS analysis by HAT. Though the carbon concentration on the surface significantly decrease during HAT, the contact profile changed less than 5{\AA}, so that the leakage current of gate, called as short channel effect, rarely degraded. [Preview Abstract] |
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NW1.00028: Seeking Methods to Reduce the Aspect Ratio Dependence in Deep Silicon Etch Robert L. Bates, M.J. Goeckner, L.J. Overzet We are examining how to reduce the Aspect Ratio Dependence (ARD) of deep silicon etch processes while maintaining both smooth sidewalls and an acceptable etch rate. In particular, SF6/O2/Ar and SF6/C4F8/Ar plasmas have both been shown to etch silicon with good anisotropy in a continuous etch process producing good sidewall profiles and at acceptable etch rates. Unfortunately, these processes also suffer from significant ARD. We are proposing to use an ARD deposition process to balance the ARD of the etch process and thereby find a reasonably AR independent process having an acceptable overall etch rate. To do this, we propose to examine both the ARD deposition rate into various AR trenches and the ARD etch rate of the passivation layer in those trenches. We are pursuing this in part because other researchers have shown that the etch rate of low AR features can be reduced (by depositing a passivation layer) and allow larger AR features to ``catch up.'' As a result, the same depth trench can be obtained [1]. The work is being carried out in a Plasma-Therm Versaline reactor in the UTD clean room. \\[4pt] [1] See for example: S. Lai, D. Johnson {\&} R. Westerman, J.Vac. Sci. Tech. A, 24, 1283, (2006). [Preview Abstract] |
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NW1.00029: Feature Profile Simulations and Finite Penetration Depth Paul Moroz, Daniel Moroz In plasma materials processing, energetic ions, neutrals and UV photons typically penetrate deep inside solid materials breaking atomic bonds and displacing atoms on their paths. These important phenomena are rarely taken into consideration in processing simulation software, primarily because the proper penetration depths and the corresponding energy depositions, breaking bonds, and atom displacements are difficult and computationally expensive to compute. The FPS-3D feature profile simulator [1-2] is doing that computationally efficiently by utilizing tabulated results obtained with other methods. We discuss, compare, and present results of such simulations made with different methods, one of which is the molecular dynamics analysis. In general, molecular dynamics could be used for simulating materials processing, etching and deposition, but it is extremely computationally expensive to be used for large groups of atoms. In practice, molecular dynamics methods are too slow to be used for feature profile simulations. However, they could help in defining proper chemical reactions and corresponding rates to be used in an advanced feature profile simulator such as FPS-3D. We present results of FPS-3D simulations for Si and SiO2 etching in Ar/Cl2 and Ar/C4F6/O2 plasmas. \\[4pt] [1] P. Moroz, ``General Feature Profile Simulator FPS-3D,'' ECS Transactions, \textbf{35}, 25 (2011). \\[0pt] [2] P. Moroz, ``Numerical Simulation of Feature Profile Evolution using FPS-3D,'' IEEE Transactions of Plasma Science, \textbf{39}, 2804 (2011). [Preview Abstract] |
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NW1.00030: Precise plasma process control based on combinatorial plasma etching Makoto Sekine, Toshiya Suzuki, Keigo Takeda, Hiroki Kondo, Kenji Ishikawa, Yuichi Setsuhara, Masaharu Shiratani, Masaru Hori For the realization of super-fine plasma etching process, fluctuations of plasma parameters such as densities of radicals, ions and electrons is required to be minimized. In particular, conditions of inner surface of reactor wall can significantly influence on the radical density in subsequent plasma process owing to outgas consisting of deposited reaction products and adsorbed species from the previous process on the wall. To investigate variety of gaseous radical densities for H$_{2}$/N$_{2}$ plasma when inner wall condition was changed by the previous process, we analyzed the radical densities using vacuum ultraviolet absorption spectroscopy (VUVAS). It was clearly confirmed that the radical densities in 100-MHz capacitively coupled plasma (CCP) of H$_{2}$/N$_{2 }$were temporally changed subsequently after different kind of conditions for H$_{2}$/N$_{2}$ plasma, O$_{2}$ plasma, and air exposure. We clarified how and what kind of etched products or process gases adsorbed on inner wall surface during the previous process and what species desorbed from the wall into bulk plasmas. Then we are trying to establish a precise process control systematically based on the plasma nano-science database that is constructing using the combinatorial plasma etching approach [1]. \\[4pt] [1] C. Moon, et al., Applied Physics Express 2 (2009) 096001. [Preview Abstract] |
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NW1.00031: GPU based 3D feature profile simulation for plasma etch process Deog-Gyun Cho, Dong-Hun Yu, Yeong-Geun Yook, Won-Seok Chang, Poo-Reum Chun, Se-A Lee, Yeon-Ho Im Recently, one of the critical issues in the plasma etching processes of the nanosize devices is to achieve ultra-high deep contact hole without abnormal behaviors such as sidewall bowing and necking However, it is well-known that the predictable modeling for this plasma etching process needs heavy computations due to the inherent complexities of plasma physics and chemistry. As an effort to address this issue, we have developed ultra-fast 3D feature profile simulation codes using CUDA computing technology. In this work, the 3D feature profile simulation is mainly composed of level set based moving algorithm, ballistic transport module and surface reaction module. Especially, the ballistic transport module requiring the time consumable computations are improved drastically by CUDA based numerical schemes, leading to the real time computation. Finally we demonstrated real-time 3D feature profile simulation for ultra-high aspect contact hole etching under fluorocarbon plasma. [Preview Abstract] |
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NW1.00032: Preparation of Alq$_{3}$ thin films using a pulsed laser deposition method with cooling target by liquid nitrogen Yoshiaki Suda, Tamiko Ohshima, Hiroharu Kawasaki, Toshinobu Shigematsu, Yoshihito Yagyu, Takeshi Ihara We have prepared Alq$_{3}$ (tris (8-hydroxyquinoline) aluminum) thin films for organic electroluminescence by a pulsed laser deposition (PLD) method. The bulk Alq$_{3}$ target was not able to produce by sintering above 1,000 $^{\circ}$C, because the glass transition temperature of Alq$_{3}$ was about 160 $^{\circ}$C. Therefore, the density of Alq$_{3}$ target (about 1.3 g/cm$^{3})$ was lower than that of the target used by PLD generally. In order to stabilize the density of the Alq$_{3}$ target, we cooled the target by liquid nitrogen. The temperature of Alq$_{3}$ target cooled by liquid nitrogen was --120 $^{\circ}$C. In this study, we have prepared Alq$_{3}$ thin films by a Nd:YAG laser (532 nm) deposition method with the cooling target by liquid nitrogen. The experimental results suggest that Alq$_{3}$ thin films are deposited at the fluence above 2.3 J/cm$^{2}$. FT-IR spectra of the prepared films are as same as those of the Alq$_{3}$ powder. UV-Vis spectrum shows that the prepared films have an absorption peak around 400 nm, which is distinct absorption peak of Alq$_{3}$. The results suggest that structural and optical properties of the films prepared by cooling target are in agreement with Alq$_{3}$ for organic electroluminescence. [Preview Abstract] |
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NW1.00033: Study of thin film formation using an rf non-thermal plasma jet at atmospheric pressure Florian Sigeneger, Jan Sch\"afer, R\"udiger Foest, Detlef Loffhagen, Klaus-Dieter Weltmann The deposition of thin films using an RF-excited plasma jet at atmospheric pressure has been investigated. On flat polymer and glass samples, thin silicon-organic films have been deposited in static experiments using the silicon containing molecules HMDSO and OMCTS. The deposited films have been analysed using profilometry and Fourier transform infrared spectroscopy depending on power and flow rate. High quality films with an O/Si ratio close to two were found for laminar flow regimes. A two-dimensional axisymmetric fluid model describes the interaction of gas heating and flow, the plasma generation in the active volume, the transport of active plasma particles into the effluent and the generation and transport of precursor fragments towards the substrate surface. A remarkable influence of the gas flow on the plasma kinetics is observed only with respect to the density of molecular argon ions, which are transported together with electrons into the effluent. The calculated flux of precursor fragments onto the substrate surface qualitatively agrees with measured profiles of the film thickness. [Preview Abstract] |
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NW1.00034: High Power Pulsed Magnetron Sputtering for Deposition of Amorphous Carbon Films Takashi Kimura, Ryotaro Nishimura High power pulsed magnetron sputtering technology has been recently attracted, because target species sputtered by energetic ion bombardment are highly ionized and the energy of the ions is high enough to modify the substrate surface. In this study, the relationship between the properties of deposited films and the operating conditions of the high power pulsed plasmas has been experimentally investigated. The distance between the carbon target (80mm in diameter) and the substrate is 55mm, and the strength of magnetic field is approximately 0.04T in the vicinity of the target surface. In our experiment, the dissipated power and the repetition frequency are fixed at 50W and 50Hz, respectively. On the other hand, the maximum of instantaneous power is varied from 5kW to 30 kW by changing the duty ratio, and the magnitude of the current is also varied up to 40A. The typical deposition rate is around 5nm per minute and the typical film thickness is around 0.6$\mu$m. The films can be regarded as diamond-like carbon (DLC) films. The maximum of the hardness increases with the magnitude of the pulsed current and reaches 18GPa at 35A. [Preview Abstract] |
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NW1.00035: Plasma modification in a rotating reactor of vanadium oxide for electro-chromic devices Gamze Ongoren, Muhammed Sancak, Sorin Manolache, Neslihan Nohut, Ali Gulec, Aysegul Uygun, Lutfi Oksuz Titanium as doping material in spraying solution has been reported to enhance properties of electrochromic devices based on vanadium oxide. In this contribution, titanium tetrachloride plasma has been used for treatment of vanadium oxide powder. The treatments have been performed in a glass rotating reactor using ferrofluidic feedthroughs operated at 100 mTorr pressure and 100 W 13.56 MHz RF power; the reaction volume is 1 L and the RF coupling is capacitive using conformal copper electrodes outside of glass cylinder. UV-visible spectroscopy has been used for plasma diagnostic. Plasma treated and untreated vanadium oxide powders have been used for deposition of 100 nm electrochromic layers on ITO conductive electrodes; the deposition has been done by pyrolysis spraying hydrogen peroxide solution of materials. The deposited layers have been characterized by cyclic voltammetry, visible spectroscopy, AFM, SEM and EDS. The devices have been investigated in visible spectral range for optical transmission and color changes with applied voltages. This Work has been supported by TUBITAK TEYDEB project no:9100036 [Preview Abstract] |
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NW1.00036: Plasma characteristics of PTFE and hexafluoropropene deposition on AISI 1050 Stainless steel for lubrication Erdogan Teke, Ferhat Bozduman, Ali Gulec, Hatice Varol, Sorin Manolache, Erdem Camurlu, Cahit Kurbanoglu, Lutfi Oksuz Optical and electrical characteristics of sprayed polytetrafluoroethylene (PTFE) by Argon plasma and also hexafluoropropene (C$_{3}$F$_{6})$ plasma were measured for different plasma parameters (treatment time, type of gas, power, pressure, electrode distance). The coated thin film onto AISI 1050 stainless steel characteristics were also investigated. After the deposition, surface morphology was analysed by Scaning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), Atomic force microscope (AFM). Abrasion of samples was tested. As a result of abrasion test the PTFE plasma processes more effective than C$_{3}$F$_{6}$ coating. This Work has been supported by TUBITAK TEYDEB project no:9100036 [Preview Abstract] |
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NW1.00037: Enhancing antibacterial properties of UHMWPE via ion implantation Vincenzo Nassisi, Domenico Delle Side, Luciano Velardi, Pietro Alifano, Adelfia Tal\`a, Salvatore Maurizio Tredici In the last decades, the demand for biomaterials of antimicrobial quality sensibly increased. The essential properties of these materials must be the biocompatibility, wettability, durability and their antibacterial characteristics. One of the most important biomaterial for medical applications is the ultra high molecular weight polyethylene (UHMWPE) that it is used to make components of prosthetic knee, hip and shoulder. It is well known that the presence in UHMWPE of Ag atoms increase its antibacterial properties while Cu and its alloys are known as natural antimicrobial materials. In this work it is proposed a dedicated laser ion source (LIS) accelerator to perform ion implantation together with a systematic study of the surface properties of UHMWPE samples treated with different metals in order to modify their antibacterial characteristics. The proposed technique consists in the application of a dose of specific ions inside the first layer of the sample to be treated. This goal can be effectively achieved if the ions are preventively accelerated. This technique seems to be interesting, since it can open the way to an easier realization of antibacterial materials using various metal ions. [Preview Abstract] |
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NW1.00038: Industrial application of the decomposition of CO$_{2}$ $\cdot$ NO$_{x}$ by large flow atmospheric microwave plasma LAMP employed in motorcar Anil Pandey, Syunta Niwa, Yoshinari Morii, Shunjiro Ikezawa In order to decompose CO$_{2}$ $\cdot$ NO$_{x}$ [1], we have developed the large flow atmospheric microwave plasma; LAMP [2]. It is very important to apply it for industrial innovation, so we have studied to apply the LAMP into motorcar. The characteristics of the developed LAMP are that the price is cheap and the decomposition efficiencies of CO$_{2}$ $\cdot$ NO$_{x}$ are high. The mechanism was shown as the vertical configuration between the exhaust gas pipe and the waveguide was suitable [2]. The system was set up in the car body with a battery and an inverter. The battery is common between the engine and the inverter. In the application of motorcar, the flow is large, so the LAMP which has the merits of large flow, high efficient decomposition, and cheap apparatus will be superior.\\[4pt] [1] H. Barankova, L. Bardos, ISSP 2011, Kyoto.\\[0pt] [2] S. Ikezawa, S. Parajulee, S. Sharma, A. Pandey, ISSP 2011, Kyoto (2011) pp. 28-31; S. Ikezawa, S. Niwa, Y. Morii, JJAP meeting 2012, March 16, Waseda U. (2012). [Preview Abstract] |
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NW1.00039: Time constants in the transition between equilibrium and nonequilibrium combustion states of premixed burner flame irradiated by pulsed microwave K. Sasaki, K. Shinohara We investigated the time constants in the transition between the equilibrium and nonequilibrium combustion states. We examined the temporal variations of the optical emission intensities from the flame irradiated by pulsed microwave. The transitions (optical emissions) we detected were $C^3\Pi_u - B^3\Pi_g$ of N$_2$, $A^2\Sigma^+ - X^2\Pi$ of OH, $A^2\Delta - X^2\Pi$ of CH, and continuum at a wavelength of 430 nm. The temporal variations were approximated using exponential functions. The rise and fall time constants of the optical emission intensity of N$_2$ were 0.35 and less than 0.05 ms, respectively. Both the rise and fall time constants of the optical emission intensities of OH and CH were 0.35-0.4 ms, while the rise and fall time constants of the continuum optical emission intensity were 0.5 ms, which coincided with the time constant of the transport (flow) loss of particles. It is considered that the fall time constant of N$_2$ represents the heating (cooling) time constant of the electron energy, while its rise time constant represents the loss time constant of electrons. The time constants of electrons, OH, and CH are governed mainly by the transport loss, but the experimental results suggest additional frequencies of $(0.5 - 1) \times 10^3$ Hz for their volume losses. [Preview Abstract] |
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NW1.00040: Laser-induced breakdown stabilization of non-premixed jet diffusion flames Moon Soo Bak, Mark A. Cappelli Laser-induced breakdown is used to stabilize non-premixed jet diffusion flames under co-flow conditions well exceeding flame blow-off. Our focus has been on methane, ethane, and propane in co-flowing air. The 23 mJ, 10 ns pulse width frequency doubled output from a 15 Hz repetition rate Nd: YAG laser is focused down by a lens to generate the plasma kernel. Gas chromatography is carried out at downstream locations to determine the extent of combustion. The same laser pulse is used to carry out laser-induced breakdown spectroscopy (LIBS) to characterize the fuel-air mixing and to obtain the local equivalence ratios in the flow. Effective stabilization is found for all of the tested fuels but only when the laser-produced plasma is generated in regions of the flow where the local equivalence ratio is around a critical value. With the use of a numerical simulation, we discuss the prospects of using distributed laser pulses for volume plasma filling and control of complex jet flames. [Preview Abstract] |
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NW1.00041: Nanosecond repetitively pulsed discharge control of premixed lean methane-air combustion Moon Soo Bak, Mark A. Cappelli Two-dimensional kinetic simulations are carried out to investigate the effects of the discharge repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse widths are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns respectively, while the total power is held constant. The lower repetition rates, because of their higher pulse energies, produce a larger fraction of radicals such as O, H, and OH. Surprisingly, however, the effect on flame stabilization is found to be essentially the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization is also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied. [Preview Abstract] |
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NW1.00042: Gas-phase Reactive Oxygen and Nitrogen Species in Air Surface Dielectric Barrier Discharges by FTIR and UV spectroscopy Hung-wen Chang, Yukinori Sakiyama, Cheng-che Hsu, David B. Graves Atmospheric pressure plasmas are considered promising for biomedical treatment purpose due to the production of reactive oxygen species and reactive nitrogen species during the discharge. In this study, a surface micro-discharge system which operates at 10 kHz, 0.01 -- 1 W/cm$^2$ in ambient air is used. FTIR and UV-absorbance are used to investigate the time-average gas phase composition and time-resolved ozone concentration, respectively. The results showed that the gas composition is greatly influenced by the power consumption in plasmas. At 0.3 W/cm$^2$, the gas phase is dominant by NOx species and nearly no ozone is observed while at 0.05 W/cm$^2$ the amount of NOx is less and the ozone is dominant. Also, time-resolved ozone measurement by means of UV (254 nm) absorbance shows that ozone concentration reaches higher than 1000 ppm in the first tens of seconds and quenched within 1 minutes at high power condition. However, at low power condition no obvious quench of ozone is observed and the ozone concentration attains a steady state in response to the equilibrium of ozone generation and diffusion loss [Preview Abstract] |
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NW1.00043: Viability and apoptosis of cultured cancer cells induced by atmospheric pressure plasma jet Hea Min Joh, Sun Ja Kim, Tae Hun Chung, Sun Hee Leem Recent studies have shown that atmospheric pressure plasmas are a possible candidate in cancer therapy. In the case of biological structure damage induced by plasma treatment, the primary role is played by reactive oxygen species (ROS), UV photons, charged particles and electric fields. Among them, extracellular and intracellular ROS produced by plasma are considered to be the key constituents that induce cellular changes and apoptosis. These changes were different depending on the discharge conditions controlled by many operating parameters including applied voltage, driving frequency, supply gas and flow rate, and treatment time. Thus, the effects of operating parameters including working gases, plasma dose, treated time and media on cellular changes in plasma-cell interactions need to be investigated. The cellular changes in cultured cancer cells were detected using TUNEL assay with DAPI staining. Cell viability was investigated by using MTT assay which is a method for measurement of metabolic events leading to a reduction in cell survival and necrosis or apoptosis. Also we examined whether cell viability was dependent on plasma-induced cellular ROS generation. [Preview Abstract] |
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NW1.00044: Effect of Neoangiogenesis Using Micro-spot Atmospheric Pressure Plasma Chihiro Tsutsui, Toshifumi Komachi, Takumi Kishimoto, Takamichi Hirata, Akira Mori Using an in vitro model, we investigated the effect of the atmospheric pressure plasma irradiation to NIH3T3 and porcine aortic endothelial cells. In the plasma exposure experiment using cell proliferation was inhibited in proportion to processing time. However, it was found that this inhibitory effect was suppressed by plasma irradiation and cells are rather on an increase trend. And, in comparison with the cell growth curve for the He gas flow group, the curve for the plasma irradiation group was shifted to the left. We investigated expression analysis in the subsequent experiment with focus on factors related to angiogenesis, it was found that the transient overexpression of VEGF are observed in 24 h from the plasma irradiation. This proliferative effect is likely related to several growth factor releases due to plasma-induced reactive ion/radical interaction. [Preview Abstract] |
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NW1.00045: Development of plasma apparatus for plasma irradiation to living cell model Yoshiyuki Suda, Ryo Kato, Hideto Tanoue, Hirofumi Takikawa, Ryugo Tero Atmospheric pressure plasma has been studied for the industrial applications of biotechnology and medical care. For the development of these fields, understanding the influence of atmospheric pressure plasma on living cell and the mechanism of cell death is necessary. We focus on a basic structure of cell membrane, called lipid bilayer. Lipid bilayer is composed of lipid molecules with an amphipathic property and can be formed on hydrophilic substrates. In this paper, we report the development of the plasma apparatus for the treatment of lipid bilayer. The plasma apparatus uses a typical dielectric barrier discharge (DBD) system and employs parallel plate electrodes with a gap distance of 1 mm [1]. Each electrode is covered with a quartz plate and the substrate temperature is kept constant by cooling medium. The lower quartz electrode has a dimple, in which the substrate coated with a lipid bilayer and buffer fluid are mounted. \\[4pt] [1] Y. Sugioka, et al, IEEE Trans. Plasma Sci., in press [Preview Abstract] |
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NW1.00046: Body tissue activation using micro-spot atmospheric pressure plasma source Takumi Kishimoto, Takamichi Hirata, Chihiro Tsutsui, Masahiro Akiya, Akira Mori Experiments have been performed involving directly irradiating body tissues with atmospheric pressure plasma for various medical engineering applications of plasmas. Plasma irradiation was used to burn back dermis of rats. Then, healing and improvement of the scald areas were observed. Additionally, we devoted attention to the angiogenesis, which is a key component of the healing mechanism. Plasma irradiated rats and non treatment were performed an intravenous injection of fluorescein isothiocyanate (FITC) labelled tomato-lectin. The neo-vascular vessels were observed by a confocal laser scanning microscopy, and the quantities were calculated. Each quantity was the non treatment: 9.2 +/-- 0.77 and plasma irradiation: 18.4 +/-- 2.9. These data indicates that direct plasma irradiation involving ion/radical may promote angiogenesis, and it promotes living-body activation. [Preview Abstract] |
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NW1.00047: Self-consistent collisional-radiative model for shock tube in Jupiter atmosphere Gianpiero Colonna, Daniela Lucia Pietanza, Giuliano D'Ammando Modeling vehicle entering in planetary atmospheres is a complex problem involving thermal and chemical non-equilibrium interacting with the radiation field. In this contribution we present a kinetic model that couples self-consistently the free electron Boltzmann equation, state-to-state chemical kinetics and radiation transport equation for shock wave in Jupiter atmosphere. The rapid growth of the translational temperature, induce the increase of the energy of internal degrees, followed by dissociation and ionization. The radiation causes non-local effects, because the radiation emitted inside the shock wave, can be absorbed in different location. The fluid dynamic equations considered here are those of the one-dimensional stationary shock tube. Collisional-radiative model of hydrogen and helium atoms has been considered, including atom-atom collisions. Non-equilibrium distributions arise, showing steps and plateaux, inducing anomalous behaviors as non-monotone trend of the internal temperature of atomic species and strong interaction between the radiation field and the ionization degree. [Preview Abstract] |
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NW1.00048: Effect of the voltage waveform on induced flow of a dielectric barrier discharge plasma actuator Naohiko Shimura, Motofumi Tanaka, Hiroyuki Yasui Flow control technique using surface plasma is attracting a lot of attention because of its ability to be the innovative technology for the wide range application. In this paper, we have conducted experiments to inspect relationship of velocity of the induced flow, frequency and voltage of power source. First, when sinusoidal voltage was applied between the electrodes, the result showed the induced flow was the faster, the greater the power was, regardless of the frequency and voltage. Then, the waveform was changed to bipolar pulse with shorter ON period than that of sine wave with a frequency of 3 kHz, almost the same induced velocity was observed at the same power, regardless of the voltage waveform. By the same experiment with a frequency of 10 kHz, the relationship of induced velocity and the power was affected by the waveform unlike the case of frequency at 3 kHz. The highest induced velocity was observed in case of sine wave. Induced velocity was able to be expressed as a function of the full width half maximum of voltage waveform, under constant power. From these facts, it is believed that it is required for external electric field to be applied for more than certain period of time in order for ions to be accelerated by electric field even in a case that almost same amount of ions were generated under an almost same condition of discharge power. [Preview Abstract] |
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NW1.00049: Plasma aerodynamic control of both subsonic and supersonic flows Seong-kyun Im, Mark A. Cappelli We present both subsonic and supersonic aerodynamic flow control studies using dielectric barrier discharge (DBD) actuators. Flow-aligned DBD actuators designed to impart spanwise forcing and create streamwise vorticity are used for reattaching separated subsonic flows on inclined flat plates and trailing angled flaps. We demonstrate enhanced control authority when these DBD actuators are used in conjunction with boundary layer bleeding, also driven by DBD actuators within the bleed channels. DBD actuators of similar configuration are also used to control boundary layer separation in unstarting supersonic flows at Mach 4.7 flow condition. In these unstart studies, planer laser Rayleigh scattering is used to visualize flow features such as boundary layer thinning, thickening, and shock waves. A significant thinning of the boundary layer is observed with DBD actuation and spanwise forcing. This thinning is the result of the drawing in of high speed fluid from the supersonic core and is shown to lead to a delay in the unstart process. [Preview Abstract] |
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NW1.00050: Plasma assisted combustion of paraffin mixture Oleg Nedybaliuk, Valeriy Chernyak, Eugene Martysh, Olena Aktan, Svitlana Orlovska, Natalia Belenok, Tamara Lisitchenko The question of the additional activation of paraffin based solid fuels is examined. The use of plasma stimulation for this purpose is proposed. The mixture of n-paraffin and stearin in the solid state as the model of the solid paraffin based fuel is used. The plasma assisted combustion of this model is experimentally investigated. The voltage-current characteristics of discharge at the different regimes are measured. The emission spectrums of a flame and the plasma torch emission spectrum are obtained. The population temperatures of excited rotational levels and the flame temperature are determined. [Preview Abstract] |
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NW1.00051: Laser Induced Fluorescence Measurements of Ion Velocity in Magnetic Cusped Plasma Accelerators Natalia MacDonald, Mark Cappelli, William Hargus, Jr Cusped Field Thrusters (CFTs) are magnetized plasma accelerators that use strong cusps to shape the magnetic field and hence the electrostatic potential. The cusped magnetic field lines meter the electron transport to the anode and reduce the energetic ion flux towards the dielectric channel walls, thereby reducing the effects of erosion. This work presents time averaged laser induced fluorescence velocity measurements of the ions in the plumes of three CFT variants. These include the Cylindrical Hall Thruster (CHT), Cylindrical Cusped Field Thruster (CCFT), and Diverging Cusped Field Thruster (DCFT). Results indicate that magnetic cusps form equipotential surfaces, and that the majority of ion acceleration occurs outside of the thruster channels. [Preview Abstract] |
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NW1.00052: Influence Of Secondary Electrons Produced From Plasma Material Interaction In Presence Of Crossed Electric And Magnetic Fields Kapil Sawlani, Joshua M. Herzog, Joowon Kwak, John Foster The electron energy distribution function (EEDF) plays a very important role in determining thruster efficiency as it determines various gas phase reaction rates. In Hall thrusters, secondary electron emission derived from the interaction of energetic electrons with ceramic channel surfaces influence the overall shape of the EEDF as well as determine the potential difference between the plasma and wall. The role of secondary electrons on the discharge operation of Hall thrusters is poorly understood. Experimentally, determining this effect is even more taxing as the secondary electron yield (SEY) varies drastically based on many parameters such as incident electron energies, flux and impact angle, and also on the surface properties such as temperature and roughness. The electron transport is also affected by the profile of the magnetic field, which is not uniform across the length of the accelerating channel. The goal of this work is to map out the variation of the EEDF and potential profile in response to the controlled introduction of secondary electrons. This data is expected to serve as a tool to validate and improve existing numerical models by providing boundary conditions and SEY for various situations that are encountered in Hall thrusters. [Preview Abstract] |
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NW1.00053: WO3 nanoparticles modification for electrochromic applications using a plasma rotating reactor Muhammed Sancak, Gamze Ongoren, Sorin Manolache, Neslihan Nohut, Ali Gulec, Aysegul Uygun, Lutfi Oksuz Functional nanoparticles are required for various applications including biotechnology, analytics, nanocomposites, etc. In this contribution, a rotating reactor has been used for treatment of tungsten oxide nanopowder under titanium tetrachloride plasma environments. The reactor volume is 1 L and consist of a Pyrex glass tube. Copper electrodes outside of glass cylinder are used for RF capacitive coupling. Ferrofluidic feedthroughs at both ends of reaction chamber are sealing in order to operate under vacuum conditions. The treatments have been performed at 100 mTorr pressure and 100 W 13.56 MHz RF power. Plasma treated and untreated tungsten oxide powders have been used for deposition by pyrolysis spraying of 100 nm layers from hydrogen peroxide solution on ITO conductive electrodes. The deposited layers have been characterized by cyclic voltammetry, visible spectroscopy, AFM, SEM and EDS. The devices have been investigated in visible spectral range for optical transmission and changes with applied voltages. This Work has been supported by TUBITAK TEYDEB project no:9100036 [Preview Abstract] |
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NW1.00054: The production of magnetic nanoparticles of Iron Oxide by arc discharge in water Hamid Reza Yousefi, Sara Fathollah, Maryam Nikeyn, Shohreh Khatami Nanoparticles can be utilized for any practical application. In recent years; considerable attention has been paid to iron oxide magnetic. Iron oxide nanoparticles are the class of nanoparticle which can have useful magnetic properties. In this research, magnetic iron oxide nanoparticles were produced by Arc discharge method in water. Structural analysis carried out by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM), and Spectrophotometer. Various magnetic nanoparticles like iron carbide (Fe3c), magnetic iron oxide (magnetite /maghemite) are obtained by arc discharge method in water. In this work have been showed, the influence of the time duration on the number of magnetic nanoparticles and the influence of the gap between the two electrodes on particle structure and size distribution. Furthermore, when iron nanoparticles are used under applied magnetic field, the particles would move in the direction of magnetic field. When the magnetic field is removed, the particles stop moving and still remain stably suspend in the dielectric liquid. [Preview Abstract] |
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NW1.00055: Study on synthesis processes and crystallinity changes of nanographene materials synthesized by alcohol liquid-plasma Hiroki Kondo, Tatsuya Hagino, Keigo Takeda, Kenji Ishikawa, Hiroyuki Kano, Makoto Sekine, Masaru Hori Nanometer-sized graphene is one of promising materials for novel applications such as electrical device, compound materials, and so forth, owing to its excellent and unique electrical, physical and morphological properties. In recent years, we have realized the high-speed synthesis, over 1mg/min., of the nanographene with high-crystallinity using in-liquid plasma. In this study, elementary steps of nanographene synthesis and crystallinity change during synthesis were investigated. A high-voltage (10 kV) 60 Hz ac-voltage was applied to the two electrodes above and below alcohol surface. After the plasma discharge for 15 minutes, nanographene materials were dispersed in the alcohols and collected by a filtration method. According to the Raman spectra, when ethanol was used, types of metal electrodes did not affect synthesis rates and crystallinity. However, when 1-butanol was used, crystallinity of nanographenes drastically changed depending on types of metal electrodes. It is because different synthesis processes depending on types of alcohols have different dependence on metal electrodes. [Preview Abstract] |
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NW1.00056: PLASMA SCIENCE I |
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NW1.00057: Effects of Boundaries on Plasma Jet Formation Mehmet Akman, Erdinc Karakas, Mounir Laroussi The dynamics of non thermal plasma jets consisting of plasma bullets change with background gas pressure. Our recent study indicates that this dependence is not limited to the pressure alone but also to a physical boundary confining the working gas flow. It is observed that in a Helium filled chamber, no plasma bullet propagation occurs; however inside the tube in which the Helium is flown into the chamber, plasma bullet propagation is visible. The physical boundary created by this tube enables the bullets to propagate while the lack thereof inside the chamber results in the diffuse plasma at the same pressure. This boundary does not need to be an object that surrounds the gas flow. This is evident when a background gas different than helium is introduced into the chamber. In this case, at the same pressure (75 torr), the diffuse plasma transitions into a jet as a result of the formation of a helium channel in which the plasma bullets propagate. The background gas creates a boundary layer around the helium flow inside the chamber. Therefore, it is believed that in order for plasma bullets to propagate, there needs to be a boundary surrounding the gas channel. In addition to this visual observation, in the case of helium, emission profile in VIS range also shows distinct transitions, specifically at 587.4nm. In this paper, experimental evidence supporting these observations explained above will be presented. [Preview Abstract] |
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NW1.00058: Modeling of radical productions and subsequent decay processes in an atmospheric pressure streamer discharge Atsushi Komuro, Ryo Ono, Tetsuji Oda A streamer discharge has been considered to be an effective production source of chemically active radicals. However, theoretical understanding of the discharge phenomenon and the chemical kinetics is still poor. This study is devoted to reveal the radical behaviors in an atmospheric pressure streamer discharge in H$_2$O/O$_2$/N$_2$ gas mixtures. The present model includes a discharge model, a gas dynamics model and chemical kinetics model with vibrationally excited molecules. It is shown that the numerically obtained axial distributions of O, N and OH radical are consistent with our experimental results. Direct dissociation processes, two-step dissociation with vibrationally excited molecules and a quenching of excited O atoms are predominant for O, N and OH radical productions, respectively. In addition, a gas temperature and decay rates of radicals in post-discharge periods are also compared with our experimental results. Numerically simulated gas temperatures in post-discharge phase increase as humidity increase. This tendency has already shown in our previous experimental results and it is successfully reproduced in our model. It is also shown that the rise in gas temperature affects subsequent radical decay processes. [Preview Abstract] |
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NW1.00059: Effect of rare gas and product concentration on the electron kinetics of He/CH4/CO2 mixtures for Syngas production Vasco Guerra, Andr\'e Janeco, Nuno Pinh\~ao In this work we study the electron kinetics in He/CH$_4$/CO$_2$ mixtures with the objective of studying Syngas production in cold or warm plasmas. The electron Boltzmann equation is solved in a hydrodynamic regime in a density gradients expansion, using a discrete ordinates numerical method. The electron collision cross sections used are based on sets published by different authors, mostly tested on two-term angular expansion solvers. However the cross sections were modified to ensure coherence between the transport parameters obtained with our Boltzmann solver and the experimental transport parameters. Warm plasma conditions are studied including both super-elastic collisions and multi-step electronic excitation and ionization from vibrational excited levels, mechanisms usually neglected in electron kinetic studies in CH$_4$ and CO$_2$. The influence of the rare gas concentration, vibrational temperature and product (CO and H$_2$) concentrations on the electron velocity distribution function, transport parameters, collision frequencies and fractional power losses is discussed. These results allow the identification of the main energy transfer channels and are a necessary step for the develop a full kinetic model. [Preview Abstract] |
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NW1.00060: Experimental characterization of the electron transport across a magnetic field barrier F. Gaboriau, R. Baude, L. Liard, G.J.M. Hagelaar Magnetized plasma transport plays a key role not only in fusion plasmas but also in low-temperature plasma sources operating at low pressure. Due to the presence of chamber walls, magnetized low-temperature plasmas can show ill-understood complex behavior while most available experimental data is too application-oriented and not detailed enough for model validation. In this context, the objective of that work is to study the magnetized transport as a problem of its own. A new dedicated laboratory set-up with flexible magnetic field has been built with simple but detailed diagnostics of the plasma transport. In addition to the commonly used Langmuir probe diagnostic, we have developed space-resolved wall-current measurements to characterize the different transport regimes governed by the classical cross field mobility and magnetic drifts. We will present and discuss the first experimental results obtained in argon discharges by varying the magnetic field intensity and the DC bias voltage on an electrode placed in front of the magnetic field region. This work is supported by French National Research Agency (project METRIS ANR-11-JS09-008). [Preview Abstract] |
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NW1.00061: Bi-ionic Dust Solitary Waves Julio Puerta, Pablo Martin Propagation of nonlinear solitary waves in dusty plasmas with two ions is analyzed. In the present treatment the mass of one of ions is assumed to be much smaller than the other one, in such way that there is enough time for ions to reach quasi thermal equilibrium. Maxwell Boltzmann factors are therefore applied for the ions an the whole dynamic is on the grain. Now we use the method of the pseudo-potential taking in to account temperature effects in function of the density of the heavy ion. In the limit where the heavy ion density tends to zero we recover effects found by other authors. Several numerical calculations for different values of the characteristic parameters will be shown using dimensionless variables. [Preview Abstract] |
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NW1.00062: Determination of collisional quenching rate coefficient of $N_2 (A^3\Sigma _u^+ )$ Yuusuke Koizumi, Susumu Suzuki, Haruo Itoh We have previously determined the collisional quenching rate coefficient of $N_2 (A^3\Sigma _u^+ )$ by an air pollutant gas [1-4]. In this paper we report the collisional quenching rate coefficient $k$' of $N_2 (A^3\Sigma _u^+ )$ by $p$-xylene (C$_{8}$H$_{10})$, which was determined to be (6.5$\pm$0.9)$\times$10$^{-9}$ cm$^{3}$/s. In addition, through repeated experiments it was found that by-products of $p$-xylene were deposited on the cathode, similarly to the cases of $m$-xylene and $o$-xylene previously reported [4], and then the current-voltage curves consistently shifed to a higher-$E$/$p_{0}$ region. To clarify the reason for this behavior, we confirmed by Auger electron spectroscopy (AES) and Fourier transform infrared spectroscopy (FTIR) that these changes in the current-voltage curves were caused by the deposition of a thin film of by-product of decomposed xylene on the cathode surface. According to the results of AES, C atoms were detected in a sample exposed to an electrical discharge, and we confirmed that the deposit of C was thickest in the case of electrical discharge in $p$-xylene. According to the results of FTIR, it was found that CH$_{2}$ and CH were obtained from the deposition of $p$-xylene. \\[4pt] [1] S. Suzuki, H. Itoh, H. Sekizawa and N. Ikuta, J. Phys. Soc. Jpn., 62, No.8, 2692-2697 (1993)\\[0pt] [2] S. Suzuki, H. Itoh, H. Sekizawa and N. Ikuta, Jpn. J. Appl. Phys., 36, 4744-4746 (1997)\\[0pt] [3] S. Suzuki, T. Suzuki and H. Itoh, Cont. of HAKONE X Saga, Japan, 132-135 (2006)\\[0pt] [4] S. Suzuki, H. Itoh, Proc. of 30th ICPIG (Belfast, UK), A1-12 (2011) [Preview Abstract] |
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NW1.00063: Nonlocal control of electron temperature in short-discharge plasma with active boundaries V.I. Demidov, S.F. Adams, E. Bogdanov, M.E. Koepke, A.A. Kudryavtsev It is known that boundaries are very important in formation of nonlocal plasma properties [1]. This study combines experimental and modeling demonstration of controlling electron temperature in a plasma with active boundaries. To demonstrate that, a short dc discharge with cold cathode and application of different voltages to the conducting discharge wall for argon plasma at 1 Torr pressure has been used in experiments and modeling. It is demonstrated in the model for this discharge that spatial distributions of electron density and temperature and argon metastable atom density depend on the dc voltage applied to different conducting parts of the wall. Applied voltage can trap within the device volume energetic electrons arising from atomic and molecular processes in the plasma. This leads to a modification in the heating of slow electrons by energetic electrons and as a result modifies the electron temperature. Conducted experiments also demonstrate that the measured electron temperature is a function of potential applied to the wall and it is possible to see increasing the electron temperature with increasing absolute value of the applied negative potential.\\[4pt] [1] E. Bogdanov, S. Adams, V. Demidov, A. Kudryavtsev, J. M. Williamson, Phys. Plasmas 17, 103502 (2010) [Preview Abstract] |
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NW1.00064: Control of Electron Energy Distribution Functions Using a Tandem Source Reactor Shyam Sridhar, Lei Liu, Weiye Zhu, Hyungjoo Shin, Vincent Donnelly, Demetre Economou The electron energy distribution function (EEDF) governs most of the reactions in plasma processing, as well as determining the intensity and wavelengths of light produced by the plasma. Therefore, measuring and controlling EEDF is essential to understand and develop advanced plasma processing technologies, and suppress damaging vacuum ultraviolet production. With the goal of gaining some added control of the EEDF, we have begun studies of a tandem source plasma reactor consisting of a helical resonator (HR) operating in conjunction with an inductively coupled plasma (ICP) main source. Operating the reactor in this configuration enables us to inject plasma from the dense upstream HR through a metal grid to the downstream ICP. Preliminary studies were conducted using this setup and the effect of upstream plasma on downstream plasma was measured using a Langmuir probe. EEDFs were obtained as a function of gas pressure, bias applied to the boundary electrode, and different grid opening sizes. For grids with openings larger than the sheath thickness, the coupling between the plasmas was found to be strong, compared to grids with openings comparable to the sheath width. In the latter case, the coupling was found to be weaker and population of low energy electrons decreased due to the injection of upstream plasma. [Preview Abstract] |
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NW1.00065: Experimental Studies of Laser-Induced Fluorescence of Kr$^+$ Greg Severn, Tim Welsh, Noah Hershkowitz We have succeeded in obtaining a laser-induced fluorescence (LIF) signal from $Kr^+$ in a low temperature Kr plasma discharge, using a diode laser, for a wavelength near 729nm. An atomic energy level scheme that is accessible to diode lasers is $^{4}D_{7/2} \rightarrow$ $^{4}P_{5/2}^0 \rightarrow$ $^{4}P_{5/2}$. The metastable state, $^{4}D_{7/2}$, one of several possible metastables states for excitation, proved to be sufficiently populated in the in a low temperature DC plasma discharge ($T_e \sim 1 eV, T_i \sim 1/40 eV, n_i \sim 10^9 cm^{-3}$) to produced a high quality signal. The excitation wavelength is nominally 729 nm, and the detected photon is nominally 473 nm. We used an extended cavity diode laser in the Littrow configuration (Sacher-Lasertechnik TEC-100-0730-20). Successful completion of these experiments will provide a new ion velocity diagnostic for Kr ions which will aid in at least 3 basic plasma science experiments: 1) Hall Thruster ion plume measurements, 2) sheath formation in the case of multiple ion species plasmas (with 3 ion species), and 3) studies of the comparison between ion velocities of metastable state rare gas ions and known ground state ion mobilities. [Preview Abstract] |
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NW1.00066: On the application of a physically based higher order fluid model for low-temperature plasmas Nathan Garland, Ron White, Robert Robson, Peter Nicoletopoulos, Sasa Dujko We present a high resolution, computationally efficient non-local fluid model of a low-temperature parallel plate plasma discharge. The non-local model uses low-order velocity moments of the Boltzmann equation representing particle, momentum and energy balance equations, coupled with Poisson's equations to determine space-charge fields. The system of equations is closed used a physically sound heat flux ansatz [1]. A new scheme is implemented for prescribing the relevant collisional terms in the balance equations, based on available electron swarm transport coefficients [2]. The model is applied to simulation of various configurations including the Gaseous Electronics Conference (GEC) reference cell and compared to previous models of the system. Results of the model yield spatial and temporal profiles of electron densities, flux and energy in addition to electric field distributions inside the GEC reference cell. In this paper, we highlight differences associated with local and non-local fluid equation treatments, as well as highlight the importance of correct implementation of electron swarm transport data. [1] R.E. Robson, R.D. White and Z. Lj. Petrovic, Rev. Mod. Phys. 77, 1303 (2005) [2] R.E. Robson, P. Nicoletopoulos, M. Hildebrandt and R.D. White, J. Chem. Phys. (sub [Preview Abstract] |
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NW1.00067: Investigation of the temporal sheath dynamics in the intermediate RF regime M. Shihab, A.T. Elgendy, D. Eremin, T. Mussenbrock, R.P. Brinkmann, I. Korolov, A. Derzsi, Z. Donko, J. Schulze The nonlinear dynamics of modulated RF plasma boundary sheaths is investigated employing a recently published model termed Ensemble In Spacetime (EST) and Particle In Cell (PIC) model. The EST enables a fast, and kinetically self-consistent simulation of all RF modulated plasma boundary sheaths in all technically relevant discharge regimes, (Shihab et al 2012 J. Phys. D: Appl. Phys. {\bf 45} 185202). A numerical experiment has been done using PIC approach with an electrically and geometrically symmetric capacitively coupled plasma. Using the resulting ion flux to the sheath and the sheath potential as input parameters, the sheath dynamics is simulated with EST as well. The results of EST are in excellent agreement with the PIC results. A huge reduction in the simulation time is achieved using EST. The ion dynamics in the intermediate regime (i.e., the ion transit time is of the order of the RF period) causes a temporal asymmetry for the sheath dynamics. The memory effects due to the ion inertia is supposed to give rise to a phase difference between the expansion and the contraction phases of the plasma sheath and consequently to a hysteresis of the sheath charge voltage relation. [Preview Abstract] |
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NW1.00068: Online platform for simulations of ion energy distribution functions behind a plasma boundary sheath Alexander Wollny, Mohammed Shihab, Ralf Peter Brinkmann Plasma processes, particularly plasma etching and plasma deposition are crucial for a large variety of industrial manufacturing purposes. For these processes the knowledge of the ion energy distribution function plays a key role. Measurements of the ion energy and ion angular distribution functions (IEDF, IADF) are at least challenging and often impossible in industrial processes. An alternative to measurements of the IEDF are simulations. With this contribution we present a self-consistent model available online for everyone. The simulation of ion energy and ion angular distribution functions involves the well known plasma boundary sheath model by Brinkmann [1-4], which is controlled via a web interface (http://sheath.tet.rub.de). After a successful simulation run all results are evaluable within the browser and ready for download for further analysis.\\[4pt] [1] R.P. Brinkmann, \textit{J. Phys. D: Appl. Phys.} \textbf{44}, 042002 (2011)\\[0pt] [2] R.P. Brinkmann, \textit{J. Phys. D: Appl. Phys.} \textbf{42}, 194009 (2009)\\[0pt] [3] R.P. Brinkmann, \textit{J. App. Phys.} \textbf{102}, 093303 (2007)\\[0pt] [4] M. Kratzer et al., \textit{J. Appl. Phys.} \textbf{90}, 2169 (2001) [Preview Abstract] |
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NW1.00069: The Bohm Criterion in Collisional Plasmas: Can the Contoversy be solved? Ralf Peter Brinkmann The existence or non-existence of a collisionally modified Bohm criterion is the subject of intense discussion, with contributions by Godyak (\textit{Phys. Lett. A} 89 80, 1982), Riemann (J. Phys. D: Appl. Phys. 24 493, 1991), Valentini (\textit{Phys. Plasmas} \textbf{3} 1459, 1996), Chen (\textit{Phys. Plasmas} \textbf{5} 804, 1997), Sternberg (\textit{Phys. Plasmas} \textbf{9} 4427, 2002), Franklin (\textit{J. Phys. D: Appl. Phys.} \textbf{36} 2821, 2003), Benilov (\textit{IEEE TPS} \textbf{28} 2207, 2000), Brinkmann (\textit{J. Phys. D: Appl. Phys.} \textbf{44}, 042002, 2011), and others. All authors agree on the fact that that collisional plasmas do not obey a Bohm criterion in a strict sense, but are add odds whether (and how) such a criterion may be formulated in an approximate sense. This contribution will propose a solution to that controversy. In particular, it will show that Godyak's and Sternberg's thesis on the existence of a collisionally modified Bohm criterion (in the interpretation by Brinkmann) and Riemann's proof of its non-existence are mathematically not in contradiction: they just reflect different opinions on what constitutes a physically reasonable approximation. [Preview Abstract] |
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NW1.00070: Plasma-Wall Interaction in Presence of Intense Electron Emission from Walls Igor D. Kaganovich, Yevgeny Raitses, Alex V. Khrabrov, Michael D. Campanell, Erinc Tokluoglu, Hongyue Wang, Dmytro Sydorenko The plasma-surface interaction in presence of strong thermionic or secondary electron emission has been studied theoretically and experimentally both as a basic phenomenon and in relation to numerous plasma applications. The electron flux to the wall is determined by the electron velocity distribution function (EVDF) and by the sheath potential, which is set by ambipolar condition consistent with the EVDF and the wall emitting properties. Nonlinear coupling between EVDF and sheath potential is responsible for a number of unusual phenomena [1]. We observed new regime where all plasma electrons leave and are substituted by secondary electrons. In this regime, there is practically no electric field in plasma and sheath, so that ions are not drawn to the wall, plasma electrons are not confined and the plasma potential is negative [2]. Finally, methods to control plasma profiles with an auxiliary electrode in dc discharges are studied experimentally [3]. \\[4pt] [1] M. D. Campanell, \textit{et al}, Phys. Rev. Lett. \textbf{108}, 235001 (2012).\\[0pt] [2] M. D. Campanell, A. Khrabrov and I. Kaganovich, to be published in Phys. Rev. Lett. \textbf{108} (2012). \\[0pt] [3] Y. Raitses, \textit{et al}, IEEE Trans. on Plasma Scie. \textbf{39}, 995 (2011). [Preview Abstract] |
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NW1.00071: Fourier Transform Infrared Spectroscopy of Trifluoroiodomethane ICP Discharge Cassius Fagioli, David Urrabazo, Matthew Goeckner Trifluoroiodomethane (CF3I) is an experimental gas that currently is being considered for semiconductor etching. We will report the breakdown characteristics of CF3I in an ICP plasma. In this study, the gas chemistry was examined through the use of Fourier transform infrared (FTIR) spectroscopy. This allowed us to identify the fraction of CF3I remaining in the discharge as well as some of the daughter species produced. Our results indicate that the major multi-atomic species found in the system include Tetrafluoromethane (CF4) and Trifluoromethyl (CF3). Mass balance examination also suggests the creation of atomic and molecular Iodide. [Preview Abstract] |
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NW1.00072: In-situ Monitoring of Surface Modification of GaN Films Exposed to Inductively-Coupled Plasmas Keiji Nakamura, Miao-Gen Chen, Yoshitaka Nakano, Hideo Sugai This paper reports in-situ monitoring of surface modification of plasma-treated GaN films based on photoluminescence (PL) technique. Irradiation of 313 nm ultraviolet (UV) light induced the photoluminescence of the GaN film, which typically consists of ~365 nm luminescence caused by transition between near band edges (NBE) andbroad yellow luminescence (YL) for an approximate wavelength range of 480-700 nm corresponding to defect-states-related transition before plasma exposure. However, after turning on discharges, a broad blue luminescence (BL) of 400-480 nm was also observed, and the BL intensity significantly increased, whereas the NBE and the YL decreased after the plasma exposure. The plasma-induced significant nitrogen deficiency near top surface will cause the decreases in both the NBE and the YL as non-emissive defects, and diffusion of the defects in the depth direction will attribute to the appearance of the BL. These results suggested that the PL measurements is useful for in-situ surface monitoring of plasma-treated GaN films. This work is partly supported by the 2nd stage Knowledge Cluster Initiative and Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Culture, Sports, Science and Technology of Japan. [Preview Abstract] |
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NW1.00073: Active Control of the Secondary Electron Emission Coefficient: A New Plasma Control Paradigm? David Urrabazo, C. Liu, L. Overzet, L. Raja, D. Breden, H. Hariswaran, P.K. Paneerchelvam Many discharges, from low to high pressure, are strongly dependent upon Secondary Electron Emission (SEE) at a cathode surface. As a result, the SEE process is generally thought to play a key role in determining plasma properties. Great efforts have been expended to control SEE from surfaces by controlling the electron work function energy through surface chemistry; but in the end, all of the standard devices suffer from one large detriment: Once the emitter/cathode is built, the magnitude of the SEE Coefficient is set. Control over SEE is possible only through changing the temperature of the surface. Recently published data, however, points to the possibility of controlling the SEE Coefficient of some surfaces in real time through the use of surface embedded electronic devices. We are just beginning an investigation of exactly this. To the best of our knowledge, no such study has ever been attempted even though it could lead to the formation of whole new classes of plasma based devices and systems. In this poster, we will describe the background physics/chemistry of the problem, the beginning of our modeling and experiments as well as the data we have obtained so far. [Preview Abstract] |
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NW1.00074: Large Volume Plasma Production in SRF Cavities with Complex Geometrical Shape Janardan Upadhyay, Joseph Newton, Alex Godunov, Svetozar Popovic, Lepsha Vuskovic Plasma based surface modification is the only technology with promises of in situ processing of superconducting radio frequency (SRF) cavities. These are the electrodynamically resonant components of complex shape, such as accelerating, deflecting, or ``crabbing'' cavities. Each shape is optimized for the electromagnetic field distribution that is needed to achieve a particularly required performance. As a result, cavity geometry is quite complex at a relatively large volume that is 5-10 liters, approximately. Hence, to create uniform plasma with varying pressure range at the resonant frequency is a nontrivial task. In this work, a simplified model of resonant microwave breakdown and the sustained plasma is developed with the goal to maximize plasma uniformity over the cavity structure. Its results are compared with the experimental results for a 1.5 GHz multiple cell accelerating structure. The model is based on the macroscopic plasma approach and the results were evaluated for the room temperature, non-superconducting conditions. We will discuss conditions and consequences of two cases, where free and ambipolar diffusion are dominant. Besides the symmetrical accelerating structures, the model for more complex, asymmetric, cavities is being developed and will be discussed. [Preview Abstract] |
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NW1.00075: Adsorption and reactivity of O and N atoms on oxide surfaces under plasma exposure D. Marinov, O. Guaitella, A. Rousseau Interaction of nitrogen and oxygen atoms with oxide surfaces (SiO2, pyrex, TiO2) was studied. Stable N (O) were grafted to the surface by a low pressure ($\sim $1 mbar) rf discharge in N$_{2}$ (O$_{2})$ and then characterized by a number of techniques. Conversion and production of new molecules (such as NO, NO$_{2})$ on the surface catalyzed by O$_{ads}$ and N$_{ads}$ was investigated using in-situ laser absorption measurements. Reactivity of adsorbed atoms under plasma exposure was studied with isotopic substitution technique. Typically, the pretreated surface containing $^{14}$N$_{ads}$ (or $^{16}$O$_{ads})$ was exposed to a pulsed discharge in isotopic gas $^{30}$N$_{2}$ (or $^{36}$O$_{2})$ and production of $^{14}$N$^{15}$N (or $^{16}$O$^{18}$O) on the surface was monitored using a quadrupole mass spectrometer. This allowed absolute measurements of the density of adsorbed species and assessment of the role of chemisorbed atoms as active sites for surface recombination. Kinetics of adsorption and desorption processes was studied by varying the duration of plasma exposure. It was found that under direct plasma exposure not only adsorbed atoms but also atoms of the material participate in surface reactions. Oxygen atoms composing the outmost layer of silica-like surfaces are continuously exchanged with the gas phase O and N atoms produced in the discharge. [Preview Abstract] |
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NW1.00076: Reaction model for etching surface interacted with hydrofluorocarbon plasmas Kenji Ishikawa, Yusuke Kondo, Yudai Miyawaki, Toshio Hayashi, Makoto Sekine, Keigo Takeda, Hiroki Kondo, Masaru Hori We report a model for plasma etching on the basis of understanding interactions between hydrofluorocarbon plasmas and dielectric surface. To construct the model, we carried out quadpole mass spectroscopic measurements of cracking patterns with changing electron energy of ionization, and estimated the cross-sections for ionizing dissociation of gases such as CH$_{x}$F$_{4-x}$ (x:1-3) molecules. Assuming a electron temperature, rate constants for these reactions were calculated by integrating over whole electron energy range. Next we made comparison in performance for plasma etching among CHF$_{3}$, CH$_{2}$F$_{2}$ and CH$_{3}$F gases by measuring densities of both ions and radicals and compared the results of etch rate with the results of the densities of the species in gas phase. For CHF$_{3}$, CH$_{2}$F$_{2}$ and CH$_{3}$F molecules, hydrogen atom was dissociated easier than fluorine atom. Cross section is ordered by CH$_{3}$F $>$ CH$_{2}$F$_{2} >$ CHF$_{3}$. According to the experimental results, the chemical reaction model was constructed and we have evaluated interaction of dielectric surface with hydrofluorocarbon plasmas. [Preview Abstract] |
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NW1.00077: 3D feature profile simulation based on realistic surface kinetic studies of silicon dioxide etch process in fluorocarbon plasmas Won-Seok Chang, Dong-Hun Yu, Deog-Gyun Cho, Yeong-Geun Yook, Poo-Reum Chun, Se-A Lee, Deuk-Chul Kwon, Mi-Young Song, Jung-Sik Yoon, Yeon-Ho Im Low pressure fluorocarbon plasmas are commonly used in microelectronics fabrication of plasma etching of dielectric materials. Recently, one of the critical issues in the etching processes of the nanoscale devices is to achieve ultrahigh deep contact hole without anomalous behaviors such as sidewall bowing and twisting profile. To achieve this goal, the fluorocarbon gases have been used to optimize the reactant fluxes and obtain the ideal etch profile. However, the semiconductor industries still suffer from the absence of the robust and predictable modeling tools due to the inherent complex plasma chemistry. As an effort to address this issue, we have developed a 3D topography simulator using the level set algorithm based on new memory saving technique, which is suitable in the contact hole etching. For this feature profile simulation, we performed a fluorocarbon plasma-surface kinetic modeling based on our experimental data, a polymer layer based this model was proposed as considering material balance of deposition and etching through steady-state FC layer. Finally, the modeling results showed good agreements with experimental data and could be used successfully for 3D etch profile simulations with consideration of polymer layer. [Preview Abstract] |
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NW1.00078: POST-DEADLINE ABSTRACTS |
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NW1.00079: Design of an ECR coaxial microwave plasma source using solid state microwave generator Louis Latrasse, Marilena Radoiu Since the use of electrodes in plasma processing presents many disadvantages, e.g. contamination or corrosion, microwaves are frequently used to supply high density plasmas. Stable and reliable microwave plasma equipment based on magnetrons and designed for automatic control of the operating variables has already proved its efficiency in low temperature diamond deposition, exhaust gas abatement, thin film deposition, etc. Large-scale processing with high density and uniform plasma is necessary for surface treatments that need highly uniform etching or deposition rates. To meet these industrial requirements, Sairem has designed a new ECR coaxial microwave plasma source with very high performances in terms of plasma density and working pressure range. Furthermore, each plasma source has its own microwave generator, the solid state generator developed by Sairem, which uses transistor technology. The advantages and the performance of this combination of technology will be reported. For example, plasma scaling up requires to distribute and apply uniform electric field over large areas. Thus, by distributing the plasma sources and by controlling the supply of power of each source, it is now possible to produce large, uniform and high density plasma without scale limitation. [Preview Abstract] |
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NW1.00080: Development of a high-power non-ablative capillary discharge source for plasma-materials interactions studies Michael Pachulio, Francesco Stefani, Roger Bengtson, Laxminarayan Raja We report the development of a new non-ablative high-pressure thermal plasma capillary discharge source for studying plasma-surface materials interactions phenomena under pulsed plasma conditions. A key requirement is to allow for a high degree of control over the composition, power, and energy of the plasma, which is not achievable with classical ablative-liner supported capillary discharges. This paper describes the design and performance of a non-ablative capillary discharge that uses a quartz liner, to produce $\sim$1 eV argon thermal (near-equilibrium) plasma. We describe an approach to reliably ignite the source using a secondary wire electrode that creates a travelling surface discharge along the quartz surface prior to the main discharge event. The argon feed-gas contains 2\% hydrogen for permitting additional spectroscopic diagnostics of the plasma. Measurements of plasma temperature, plasma density, and power are provided for various configurations of the power supply and capillary which was operated between 4 and 25 kV. [Preview Abstract] |
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NW1.00081: Atmospheric Gaseous Plasma with Large Dimensions Sergey Korenev The forming of atmospheric plasma with large dimensions using electrical discharge typically uses the Dielectric Barrier Discharge (DBD). The study of atmospheric DBD was shown some problems related to homogeneous volume plasma. The volume of this plasma determines by cross section and gas gap between electrode and dielectric. The using of electron beam for volume ionization of air molecules by CW relativistic electron beams was shown the high efficiency of this process [1, 2]. The main advantage of this approach consists in the ionization of gas molecules by electrons in longitudinal direction determines by their kinetic energy. A novel method for forming of atmospheric homogeneous plasma with large volume dimensions using ionization of gas molecules by pulsed non-relativistic electron beams is presented in the paper. The results of computer modeling for delivered doses of electron beams in gases and ionization are discussed. The structure of experimental bench with plasma diagnostics is considered. The preliminary results of forming atmospheric plasma with ionization gas molecules by pulsed nanosecond non-relativistic electron beam are given. The analysis of potential applications for atmospheric volume plasma is presented. Reference: [1] S. Korenev. ``The ionization of air by scanning relativistic high power CW electron beam,'' 2002 IEEE International Conference on Plasma Science. May 2002, Alberta, Canada. [2] S. Korenev, I. Korenev. ``The propagation of high power CW scanning electron beam in air.'' BEAMS 2002: 14th International Conference on High-Power Particle Beams, Albuquerque, New Mexico (USA), June 2002, AIP Conference Proceedings Vol. 650(1), pp. 373-376. December 17. [Preview Abstract] |
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NW1.00082: The Pulsed Cylindrical Magnetron for Deposition Sergey Korenev The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered. [Preview Abstract] |
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NW1.00083: Pulmonary and heart diseases with inhalation of atmospheric pressure plasma flow Takamichi Hirata, Shigeru Murata, Takumi Kishimoto, Chihiro Tsutsui, Akane Kondo, Akira Mori We examined blood pressure in the abdominal aorta of mini pig under plasma inhalation of atmospheric pressure plasma flow. The coaxial atmospheric pressure plasma source has a tungsten wire inside a glass capillary, that is surrounded by a grounded tubular electrode. Plasma was generated under the following conditions; applied voltage: 8 kVpp, frequency: 3 kHz, and helium (He) gas flow rate: 1 L/min. On the other hand, sphygmomanometry of a blood vessel proceeded using a device comprising a disposable force transducer, and a bedside monitor for simultaneous electrocardiography and signal pressure measurements. We directly measured Nitric oxide (NO) using a catheter-type NO sensor placed in the coronary sinus through an angiography catheter from the abdomen. Blood pressure decreased from 110/65 to 90/40 mm Hg in the animals \textit{in vivo} under plasma inhalation. The NO concentration in the abdominal aorta like the blood pressure, reached a maximum value at about 40 s and then gradually decreased. [Preview Abstract] |
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