Bulletin of the American Physical Society
71st Annual Gaseous Electronics Conference
Volume 63, Number 10
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session FT3: Microdischarges |
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Chair: John Foster, University of Michigan Room: Oregon Convention Center A106 |
Tuesday, November 6, 2018 2:00PM - 2:15PM |
FT3.00001: Student Excellence Award Finalist: Three Dimensional Microplasma/Metal/Dieletric Photonic Crystal : Dynamic Bandstop Filters Peter P. Sun, Wenyuan Chen, Runyu Zhang, Zhihu Liang, Paul Braun, J.Gary Eden We demonstrate dynamic bandstop filters in the 120 -- 170 GHz region based on 3D photonic crystals microcolumn plasmas in metal/dielectric scaffold. Comprising 200 - 400 micrometer diameter columns of low temperature plasma, these photonic crystals have functional structures with staggered geometries capable of being reconfigured electronically. The Blue shifts of specific attenuation peaks by more than 2 GHz has been demonstrated through one 3D dielectric plasma photonic crystal design. Narrow band (\textless 1GHz) attenuation over 18 dB is demonstrated at 138 GHz through 3D metallic plasma photonic crystals. The presence of plasma also increases the Q of several resonances to \textgreater 2000. The ability to control three-dimensional arrays of microplasma columns in compact (\textasciitilde 100 mm$^{\mathrm{3}})$ polymer structures offers enormous versatility for microwave devices and communications systems. [Preview Abstract] |
Tuesday, November 6, 2018 2:15PM - 2:30PM |
FT3.00002: Study of long lifetime DC microdischarges on silicon elaborated by MEMS fabrication techniques Ronan Michaud, Arnaud Stolz, Sylvain Iseni, Olivier Aubry, Philippe Lefaucheux, Sebastian Dzikowski, Volker Schulz-von der Gathen, Leanne Pitchford, Rémi Dussart DC microdischarges can operate in a stable and non-thermal regime at atmospheric pressure with breakdown voltage below 300V [1]. By MEMS fabrication techniques it is possible to elaborate micro hollow cathode discharge (MHCD) directly integrated on silicon. This provides a large field of applications like micro-sensors on chip or surface treatment. However using silicon as cathode material, the discharge does not operate in a stable regime and the lifetime is very short. By changing the cathode material, it is possible to obtain a stable discharge even at atmospheric pressure with a high current density operating in He during more than 24 hours [2]. This study compares three different geometries (planar, cavity and hollow) of long lifetime DC microdischarges operating in different gases (He, Ar, N2, mixtures) Experimental characterizations by electrical and optical measurements were performed and compared to simulations using a fluid model developed at LAPLACE (Toulouse). A portable device integrating these DC microdischarges was also developed for gas treatment applications. [1] K.H. Schoenbach et al 1997 Plasma Sources Sci. Technol. 6 468--477 [2] R. Michaud et al 2018 Plasma Sources Sci. Technol. 27 025005 [Preview Abstract] |
Tuesday, November 6, 2018 2:30PM - 2:45PM |
FT3.00003: Voltage Waveform Tailoring in microscopic atmospheric pressure radio-frequency plasma jets Ihor Korolov, Andrew Gibson, Lena Bischoff, Gerrit Hübner, Jerome Bredin, Zoltan Donko, Peter Hartmann, Thomas Mussenbrock, Timo Gans, Deborah O'Connell, Julian Schulze Microscopic atmospheric pressure plasma jets are important tools for biomedical applications and surface modifications. They are typically operated at a single driving frequency with limited control of the electron power absorption dynamics and the Electron Energy Distribution Function (EEDF). For such applications the generation of reactive species, e.g. reactive oxygen and nitrogen species, at low temperatures plays a key role. Based on experiments and kinetic Particle-in-Cell/Monte Carlo simulations, we demonstrate that Voltage Waveform Tailoring (VWT) allows to control the spatio-temporal excitation/ionization dynamics and the EEDF as the basis to optimize the generation of selected reactive particle species. [Preview Abstract] |
Tuesday, November 6, 2018 2:45PM - 3:00PM |
FT3.00004: Plasma properties of DC silicon based micro hollow cavity discharge (MHCD) operating in various gases - a spectroscopic study Sylvain Iseni, Ronan Michaud, Claudia Lazzaroni, Philippe Lefaucheux, Volker Schulz-von der Gathen, Goran Sretenovic, Remi Dussart Taking advantage of MEMS fabrication technologies, silicon (Si) based MHCD allow reducing significantly the electrode gap (8$\mu$m SiO$_2$ layer) and the cavity size (50 to 200$\mu$m diameter, 30$\mu$m depth). Operated in DC at pressure ranges from 10$^4$ to 10$^5$ Pa, the plasma ignites in the cavity and operates in the normal or abnormal regime. Although Si-based MHCD operating in DC used to suffer from their short lifetime, recent advances on the design allow for extending their lifetime~[1]. This study focuses on the measurement of the gas temperature in and out the cavity by means of space resolved optical emission spectroscopy. Two approaches are applied depending on the gas mixture (He, Ar, N$_2$, O$_2$, H$_2$O): either by studying the profile of resonant atomic lines or with the determination of the N$_2$(C-B) rotational temperature. Limitations of the latter approach will be discussed specifically. In addition, the electron density and the electric field value within the cavity have been investigated. [1]~R.~Michaud~et.~al., PSST, 27, 025005 (2018). [Preview Abstract] |
Tuesday, November 6, 2018 3:00PM - 3:15PM |
FT3.00005: Tailoring electron heating in rf capacitive discharges at atmospheric pressure Sanghoo Park, Wonho Choe, Se Youn Moon, Jian Jun Shi Over the several decades, the tailoring electron heating has been actively attempted to control the electron characteristics in ionized gases, but it has been tough to achieve the desired outcome due to its nonlinear nature. In this presentation, we report the electrical characteristics and electron information in single-frequency (4.52 MHz and 13.56 MHz) and dual-frequency (a combination of 4.52 MHz and 13.56 MHz) capacitive discharges in the abnormal $\alpha $-mode at atmospheric pressure. A continuum radiation-based electron diagnostic method is employed to estimate the electron density ($n_{\mathrm{e}})$ and temperature ($T_{\mathrm{e}})$. Our experimental observations reveal that time-averaged $n_{\mathrm{e}}$ (7.7--14 × 10$^{\mathrm{11}}$ cm$^{\mathrm{-3}})$ and $T_{\mathrm{e}}$ (1.75--2.5 eV) can be independently controlled in dual-frequency discharge, whereas such control is nontrivial in single-frequency discharges, which shows a linear increase in $n_{\mathrm{e}}$ and little to no change in $T_{\mathrm{e}}$ with increases in the rf input power. Furthermore, the two-dimensional spatiotemporal evolution of neutral bremsstrahlung and associated electron heating structures is demonstrated. These results reveal that a symmetric structure in electron heating becomes asymmetric (via a local suppression of electron temperature) as two-frequency power is simultaneously introduced. [Preview Abstract] |
Tuesday, November 6, 2018 3:15PM - 3:30PM |
FT3.00006: Study of Ar/N$_{\mathrm{2}}$ microplasma sources for the production of atomic nitrogen for nitride deposition Salima Kasri, Kristaq Gazeli, Joao Santos Sousa, Gerard Bauville, Michel Fleury, Stephane Pasquiers, Ludovic William, Xavier Aubert, Guillaume Lombardi, Jocelyn Achard, Alexandre Tallaire, Claudia Lazzaroni A ns-pulsed Micro-Hollow Cathode Discharge (MHCD) array reactor running in Ar/N$_{\mathrm{2}}$ has been studied and developed, the objective being the production of high densities of atomic nitrogen for material deposition. MHCDs are a type of microplasmas in which a set of holes of several hundreds of micrometers in diameter is drilled through an electrode-dielectric-electrode sandwich structure. MHCDs generate high electron densities (up to 10$^{\mathrm{16}}$ cm$^{\mathrm{-3}})$, potentially allowing a high dissociation degree of nitrogen molecules, which is particularly suited for nitride deposition. The microplasma reactor is composed of two chambers at different pressure levels, with the MHCD array located at their junction. The high-pressure chamber (50 mbar) favors the production of high-density plasmas and, consequently, the nitrogen dissociation, while the low-pressure chamber (1 mbar) limits the nitrogen recombination. 1 and 7 MHCDs operating in different Ar/N$_{\mathrm{2}}$ gas mixtures have been experimentally characterized by using different diagnostics (electrical measurements, optical emission spectroscopy and fast imaging) to better understand the physics of the discharge. This has been done by varying the repetition frequency rate (10 to 40 kHz) and the Ar to N$_{\mathrm{2}}$ ratio in the gas mixture. [Preview Abstract] |
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