Bulletin of the American Physical Society
73rd Annual Gaseous Electronics Virtual Conference
Volume 65, Number 10
Monday–Friday, October 5–9, 2020; Time Zone: Central Daylight Time, USA.
Session SR4: High Pressure Discharges and Microdischarges IILive
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Chair: Tanvir Farouk, University of South Carolina |
Thursday, October 8, 2020 8:00AM - 8:15AM Live |
SR4.00001: Experimental characterization of a MHCD in Ar/N$_{\mathrm{2}}$ mixture: Ar(1s$_{\mathrm{5}})$ and N density measurements by absorption spectroscopy Alice Remigy, Claudia Lazzaroni, Guillaume Lombardi, Hiba Kabbara, Ludovic Williams, Gérard Bauville, Thibault Darny, Kristaq Gazeli, Stéphane Pasquiers, Joao Santos-Sousa, Nelson De Oliveira An experimental characterization of a Micro Hollow Cathode Discharge (MHCD) in Ar/N$_{\mathrm{2}}$ mixture, used in a deposition reactor of hexagonal boron nitride (h-BN), has been carried out. h-BN is a highly requested material for electronic and optoelectronic, given its large band gap and compatibility with graphene. The absolute densities of N-atoms and metastable argon (Ar(1s$_{\mathrm{5}}))$ have been measured. Ar (1s$_{\mathrm{5}})$ is an important species in the dissociation process of N$_{\mathrm{2}}$, whereas N-atoms are required for growing h-BN films. The Ar (1s$_{\mathrm{5}})$ has been measured by means of tunable diode laser absorption spectroscopy (TDLAS) and the N-atoms density was assessed with the VUV high resolution Fourier Transform spectrometer of the DESIRS beamline of the SOLEIL synchrotron. We have performed a parametric study, varying the MHCD hole diameter, the percentage of N$_{\mathrm{2}}$ in the Ar/N$_{\mathrm{2}}$ mixture, the discharge current and the gas pressure, so as to investigate their effect on the absolute densities of Ar(1s$_{\mathrm{5}})$ and N-atoms. The results are compared to those of a global model of the MHCD. [Preview Abstract] |
Thursday, October 8, 2020 8:15AM - 8:30AM Live |
SR4.00002: Computational studies of the frequency response of impedance characteristics of a plasma capacitor Saurav Gautam, Gabriele Morra, Venkattraman Ayyaswamy Microplasmas ignited at atmospheric pressure provide a useful building block for the development of tunable electrical and electronic components with potentially useful properties that cannot be achieved by traditional electronic components. One such attractive property is the negative capacitance that can be demonstrated by plasmas at input frequencies higher than the plasma frequency. While simple analytical models assuming a fixed electron number density can be used for preliminary analysis of impedance characteristics of microplasmas, the strong spatial gradients make it necessary to use numerical methods for more accurate analyses. In this talk, we present computational studies of the impedance characteristics and its frequency dependence in the microwave frequency regime for a microplasma capacitor. The microplasma is ignited using a specified input power at a frequency of 100 MHz with an additional low-voltage (about 1 V) high-frequency input signal used to analyze the frequency response of the reactance. The low-voltage input signal ensures that its influence on the baseline plasma is negligible. The impedance variation shows negative capacitance (positive impedance resembling an inductor) at a certain frequency which can be tuned by modifying the input power delivered to ignite the plasma. [Preview Abstract] |
Thursday, October 8, 2020 8:30AM - 8:45AM Live |
SR4.00003: Investigation On Gap Arrangements For Pseudo Spark Based High Current Density Electron Beam Generation K. Singhal, S. Jain, Vishant . In recent time, Pseudo spark (PS) discharge driven devices have been used for strategic applications like millimetre-wave generation and switching. The PS discharge generally operates in the range of 50-500 mTorr gas pressure to create plasma inside the hollow cathode cavity by applying electric field. The formation of plasma inside the hollow cathode cavity depends upon different geometrical design parameters like aperture size and shape, number of gap insulator and arrangement of the inter electrode gap etc. Researchers have worked on the role of aperture, beam shape, aspect ratio, etc. More attention is needed in the direction of gap arrangement for PS based high current density electron beam generation. Therefore, in the present work, analysis of inter-electrode gap structure inside the PS based electron beam source has been performed. Simulation study has been performed for multi gap structures using COMSOL Multiphysics. The delayed breakdown behaviour has been analysed using different multi-gap structures. The number of gaps has been varied between 3 to 8 for different applied gap voltages ranging between 20 kV-40 kV. The simulation studies have been carried out to analyse effects of gap structure on the generation of energetic and high current density electron beam. Comparative analysis has also been performed using self-breakdown experiments by applying gap voltage similar to the simulation studies. These studies will be helpful for design and development of high power sub-THz oscillator. [Preview Abstract] |
Thursday, October 8, 2020 8:45AM - 9:00AM Live |
SR4.00004: Relationship between current waveform and Taylor cone tip vibration in Trichel-like pulse discharge from liquid-filled nozzle electrode Fumiyoshi Tochikubo, Keisuke Nagao, Yusuke Nakagawa, Satoshi Uchida Electrospray as a common tool for the source of fine liquid droplets is formed by applying a high voltage between a liquid-filled nozzle electrode and a plate electrode. When a negative high voltage is applied to the liquid-filled nozzle electrode, Trichel-like pulse discharge is generated simultaneously with the electrospray. In Trichel-like pulse discharge, current pulse groups repeatedly and regularly appear with intervals. In each pulse group, a number of current pulses with duration shorter than 200 ns follow a large initial pulse with an increase in their height and interval$^{(1)}$. The shape of pulse group as well as droplet emission strongly depends on both discharge and liquid conditions. In this work, we experimentally investigated the current waveform of Trichel-like pulse discharge as parameters of applied voltage, discharge gap, conductivity and viscosity of liquid. The vibration of Taylor cone tip as well as droplet emission was observed by a high speed camera synchronized with the current waveforms. The tip of Taylor cone vibrates with a displacement of 20-40 $\mu$m synchronized with the frequency of pulse group appearance, which is influenced by the liquid viscosity. (1)T. Sugimoto et al., J. Electrostat. $\bf 53$ (2001) 25. [Preview Abstract] |
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