Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session ER1: Thermal and Arc Plasma II |
Hide Abstracts |
Chair: Masaya Shigeta, Tohoku University Room: Sendai International Center Hagi |
Thursday, October 6, 2022 8:00AM - 8:15AM |
ER1.00001: Numerical Simulation of Time Evolution of Cathode Sheath Voltage Contributing to Evaporation of Fe Cathode in Vacuum Arc Masahiro Takagi, Hiroto Suzuki, Honoka Morishita, Yuki Suzuki, Yusuke Nemoto, Zhenwei Ren, Reggie C Gustilo, Toru Iwao It has been required to elucidate physics of cathode spots in vacuum arc in order to control it for industrial applications. The cathode spots in vacuum arc moves at high speed with evaporation from cathode metal caused by ion heating. The ion bombardment, which is the heating factor of the cathode, occurs when ions generated from the thermal plasma are accelerated in the cathode sheath and bombard the cathode. This heating is considered to cause the cathode to melt and evaporate, forming a new plasma spot. Since the cathode sheath voltage depends on the behavior of the plasma and the amount of electron emission from the cathode, it is considered that spatial distribution and variation with time of cathode sheath are formed. However, few papers have been quantitatively researched. In this research, it was constructed that numerical simulation based on electromagnetic thermodynamic fluid analysis coupled with an analysis of the electrostatic field in the cathode sheath. The analysis of electrostatic field in the cathode sheath was computed based on the Poisson's equation. Using this simulation model, it was analyzed that the spatial and time evolution in the cathode sheath voltage distribution contributing to the evaporation of the cathode metal. |
Thursday, October 6, 2022 8:15AM - 8:30AM |
ER1.00002: Investigation of the electro-thermal dynamics of a low pressure DC plasma spray torch Ram K Mohanta, Ganesh Ravi The dynamics a DC plasma torch is studied experimentally in the pressure range of 1 – 30 mbar, with a focus on low pressure spraying and coating applications. The low pressure plasma spray technique bridges the gap between physical vapor deposition (PVD), chemical vapor deposition (CVD) techniques and atmospheric plasma spray processes. Hence, it becomes imperative to study the plasma torch dynamics. In this study, the effect of various operating conditions such as (i) pressure (ii) gas flow rate (iii) type of gas (iv) arc current and (v) anode geometry on the electro-thermal output of the plasma torch is investigated. Current-voltage characteristics (CVC) of plasma torch with different operating parameters are explored, highlighting their differences. A semi-empirical relation between voltage and current is constructed using theory of dynamic similarity to predict the behaviour of the DC plasma torch under low pressure conditions (1 – 30 mbar). The influence of input controllable parameters on the output of the plasma torch is highlighted using dimensionless numbers. This study also unravels interesting correlations between the anode exit diameter and the threshold limit for subsonic to supersonic transition of the jet at 30 mbar chamber pressure. The spectral analysis reveals the different fluctuations associated with the arc voltage, classified into three different modes (i) restrike (ii) Helmholtz and (iii) acoustic. While the restrike mode is superimposed over the complete spectrum and the power density is constant, the power associated with the Helmholtz mode and acoustic mode oscillations have direct correlation with the kinetic energy component influencing the plasma jet velocity. The power density corresponding to the Helmholtz mode and acoustic mode acts as a signature of the transition from subsonic to supersonic regime. |
Thursday, October 6, 2022 8:30AM - 9:00AM |
ER1.00003: Generation of stationary high-density cascade arc plasmas and its application to plasma windows Invited Speaker: Shinichi Namba In order to realize plasma windows for virtual vacuum interfaces, we have developed cascade arc plasma sources. For windowless vacuum–atmosphere separation, a compact arc discharge source having a channel diameter of 3 mm is fabricated, and an atmospheric Ar thermal plasma is generated. For an alternative differential pumping system, separating low- and high-pressure vacuum chambers, a larger arc device with an 8-mm diameter is also constructed, producing a high-density He plasma. The performances of the two cascade arcs as plasma windows are investigated by variations of pressure gradient between high- and low-pressure chambers and by UV/visible emission spectroscopy. The 3-mm arc discharge generates a steep pressure gradient of Ar 100 kPa–100 Pa through the discharge channel, while the 8-mm discharge apparatus isolates the high-pressure side at 7 kPa from the lower pressure of 54 Pa. Emission spectroscopy determines the electron density and temperature of Ar and He plasmas, yielding the temperature of ~1 eV (Boltzmann plot) in both discharges and electron density of 1.5×1016 cm-3 for Ar 35 A with a gas flow rate of 5.0 l/min and 1.5×1014 cm-3 under a He 100-A and 0.5-l/min condition by means of Stark broadenings of the H-b and Ar I lines. |
Thursday, October 6, 2022 9:00AM - 9:15AM |
ER1.00004: Arc resistance increasing during DC interruption using SiO2/Si3N4 mixture powder as arc interruption medium Naoto Kodama, Yasunobu Yokomizu, Waku Takenaka, Kaito Hasegawa This paper applied mixture powder of silica-sand(low-purity SiO2 sand) and silicon-nitride(Si3N4) as new direct-current(DC) arc interruption medium. The present research carried out theoretical calculation of gas properties for SiO2/Si3N4 mixture arc and a DC arc interruption experiment using the mixture powder. As a calculation result of gas properties, thermal conductivity was increased with Si3N4 vapor admixing into SiO2 vapor. In addition, arc resistance rarc was increased under condition using the SiO2/Si3N4 mixture powder compared to rarc under condition using only the SiO2 powder. The arc resistance rise could be explained based on increase in the thermal conductivity of the arc due to the Si3N4 vapor admixing and consequent rise in thermal energy dissipation from the DC arc. |
Thursday, October 6, 2022 9:15AM - 9:30AM |
ER1.00005: Bidirectional vortex stabilization of a supersonic ICP torch Ashley Pascale, Trevor Lafleur, Cormac Corr RF inductively coupled plasma (ICP) torches with a supersonic nozzle are used for materials processing and have also been proposed as electrothermal plasma thrusters for space propulsion applications. At the relatively high operating pressures used, the gas injection method plays an important role in stabilizing the ICP discharge. Bidirectional vortex gas injection is a novel configuration that has been proposed for both subsonic ICP torches and liquid propellant combustion chambers for chemical rocket engines. In this configuration, gas is injected tangentially at the downstream end near the nozzle and first spirals up along the outer edge of the chamber before reversing direction at the upstream chamber end and spiralling back down through the central region towards the nozzle exit. Here we investigate such a bidirectional vortex with a supersonic ICP torch and show that both the effective torch stagnation temperature and thermal efficiency can be increased by almost 50% compared with conventional gas injection configurations. This enhancement occurs because of the unique vortex flow field which leads to reduced gas-wall heat losses and consequently an increased flow enthalpy leaving the torch. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700