Bulletin of the American Physical Society
74th Annual Gaseous Electronics Conference
Volume 66, Number 7
Monday–Friday, October 4–8, 2021;
Virtual: GEC Platform
Time Zone: Central Daylight Time, USA
Session RR44: Basic Plasma Physics Phenomena in Low-temperature Plasmas II |
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Chair: Greg Severn, University of San Diego Room: Virtual GEC platform |
Thursday, October 7, 2021 2:00PM - 2:15PM |
RR44.00001: Self-Consistent Model of Kinetic Striations in Noble Gases Juan G Alonso Guzman, Robert Arslanbekov, Vladimir I Kolobov
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Thursday, October 7, 2021 2:15PM - 2:45PM |
RR44.00002: Electron Dynamics and Anomalous Processes in Low- Temperature Plasmas Invited Speaker: Trevor Lafleur The role of electrons in the formation and behavior of plasmas is at once both obvious and incredibly subtle. Electrons are at the heart of plasma physics, and their complex interaction with electric and magnetic fields, together with the friction forces they experience due to collisional processes, leads to a remarkable richest and diversity in plasma properties. The disparity in spatial and temporal scales caused by just the electron mass leads to important plasma phenomena, and can result in non-local effects or instabilities that produce "anomalous" behavior: often defying intuition and conventional explanations. In this talk, we examine different plasma systems and show how a combination of experiment, theory and numerical simulation has allowed new insight into the underlying electron dynamics, and a better understanding of overall system operation. The plasmas considered are relevant to material processing and space propulsion applications, and include both well-established systems such as RF capacitively coupled plasmas and DC Hall thrusters, as well as emerging concepts using magnetic nozzles and accelerators based on RF biased electrodes. We also discuss recent advances in our understanding of charged particle collisions, and how external magnetic fields can influence electron dynamics to produce fundamentally new collisional behavior. |
Thursday, October 7, 2021 2:45PM - 3:00PM |
RR44.00003: On the justification of the Poisson-Boltzmann equation in the context of technological plasmas Ralf Peter Brinkmann, Kevin Koehn, Dennis Krueger, Efe Kemaneci, Denis Eremin The Poisson-Boltzmann equation is a nonlinear differential equation for the electric potential that describes equilibria of conducting fluids. Its standard justification is based on a variational principle which characterizes the thermodynamic equilibrium of a system in contact with a heat reservoir as a minimum of the Helmholtz free energy. The Poisson-Boltzmann equation is also employed for the electron component of technological plasmas. There, however, the standard justification is inapplicable: The electrons of technological plasmas are neither in thermodynamic equilibrium nor in contact with heat reservoirs. This study presents an alternative variational principle which is based on the functionals of entropy, particle number, and electromagnetic enthalpy. It allows to justify the Poisson-Boltzmann equation for a wide class of technological plasmas under realistic assumptions. |
Thursday, October 7, 2021 3:00PM - 3:15PM |
RR44.00004: A semi-analytical RF sheath model Tagra Samir, Ralf Peter Brinkmann The dynamics of radio frequency driven capacitively coupled plasma (RF-CCP) is, to a large extent, determined by the characteristics of the boundary sheath. Reliable models of the sheath are therefore of theoretical and practical interest. Particularly interesting are “semi-analytical” models which describe the particle densities and the electrical field of the sheath in a compact form. This contribution presents a semi-analytical model of the RF modulated boundary sheath which applies for a wide range of excitation waveforms and amplitudes, and levels of collisionality. In contrast to many other sheath models, it is not based on the quasi-static assumption and therefore suited to describe dynamical phenomena such as field reversal and anomalous heating. |
Thursday, October 7, 2021 3:15PM - 3:30PM |
RR44.00005: Characterization of the Electron Energy Distribution Function of Plasma Sphere in the Inertial Electrostatic Confinement Device with Optical Emission Spectroscopy and Collisional-Radiative Model Yung-An C Chan, Georg Herdrich The discharge behavior within inertial electrostatic confinement (IEC) devices is not yet fully understood. A working principle based on the double-layer theory is proposed to explain the discharge mechanism. [1-3] Optical emission spectroscopy (OES) is used to evaluate the non-Maxwellian electron energy distribution function (EEDF) and the respective effective electron temperature (Te) across the radius of the plasma sphere within the IEC. An optimized super-symmetrical cathode structure is implemented for the IEC device to reduce the uncertainty of the discharge [4] and argon is used as the demonstrating gas for the evaluation. |
Thursday, October 7, 2021 3:30PM - 3:45PM |
RR44.00006: Influence of the energy dependence of the electron distribution function on the stability of the electron beam - plasma system at Knudsen numbers of the order of 1 Vladimir S Sukhomlinov, Rustem J Matveev, Aleksandr S Mustafaev, Alexandr S Zaitsev, Nikolai A Timofeev Within the framework of the kinetic approach, using the example of a low-voltage beam discharge in rare gases (LVBD), stability conditions are investigated depending on the temperature of the electron beam, the dispersion of the electron beam velocity in the direction of the discharge axis, and the form of the electron energy distribution function (EEDF). Regimes are considered when the inter-electrode distance is of the order of the electron mean free path relative to elastic collisions with rare gas atoms. |
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