Speaker
Andrew Fierro
(Sandia National Laboratories)
Description
Largely absent from kinetic, low-temperature plasma simulations is the capability for simulating radiation transport. It is largely acknowledged that self-produced radiation from gas discharges may have an impact on plasma formation and there is a need to include this physics into modern simulation codes. As such, there has been some effort in including photon dynamics into plasma simulations although they are generally only applicable to a single gas mixture such as air or focus on a small subset of transitions. In this work, a thorough kinetic description of Helium is included into a massively parallel Particle-in-Cell (PIC) utilizing Direction Simulation Monte Carlo (DSMC) for electron-neutral interactions. Additionally, a method for radiation transport is included that includes both natural and Doppler line broadening as well as self-absorption mechanisms. This method demonstrates the capability of modern PIC simulations to simulate temporally and spatially-resolved emission spectra and include energy-dependent photon dynamics such as photo-emission from the electrode surfaces. One-dimensional simulations of a Townsend discharge at various pressures in pure helium depict the evolution of the excited state densities and subsequent spontaneous emission. It is shown that high-energy photons emitted from the ground state transitions of helium (41P -> 11S, 31P -> 11S, 21P -> 11S), while heavily self-absorbed by background neutral particles, are capable of reaching the cathode causing additional electron current due to photo-emission.
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\* Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
Author
Andrew Fierro
(Sandia National Laboratories)
Co-authors
Mr
Brett Scheiner
(University of Iowa)
Dr
Chris Moore
(Sandia National Laboratories)
Dr
Matt Hopkins
(Sandia National Laboratories)
