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Title: Radiation transport in kinetic simulations and the influence of photoemission on electron current in self-sustaining discharges

A kinetic description for electronic excitation of helium for principal quantum number n $$\leqslant $$ 4 has been included into a particle-in-cell (PIC) simulation utilizing direct simulation Monte Carlo (DSMC) for electron-neutral interactions. The excited electronic levels radiate state-dependent photons with wavelengths from the extreme ultraviolet (EUV) to visible regimes. Photon wavelengths are chosen according to a Voigt distribution accounting for the natural, pressure, and Doppler broadened linewidths. This method allows for reconstruction of the emission spectrum for a non-thermalized electron energy distribution function (EEDF) and investigation of high energy photon effects on surfaces, specifically photoemission. A parallel plate discharge with a fixed field (i.e. space charge neglected) is used to investigate the effects of including photoemission for a Townsend discharge. When operating at a voltage near the self-sustaining discharge threshold, it is observed that the electron current into the anode is higher when including photoemission from the cathode than without even when accounting for self-absorption from ground state atoms. As a result, the photocurrent has been observed to account for as much as 20% of the total current from the cathode under steady-state conditions.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Iowa, Iowa City, IA (United States)
Publication Date:
Report Number(s):
SAND-2016-11833J
Journal ID: ISSN 0022-3727; 649379; TRN: US1700998
Grant/Contract Number:
AC04-94AL85000; AC05-06OR23100; SC0001939
Type:
Accepted Manuscript
Journal Name:
Journal of Physics. D, Applied Physics
Additional Journal Information:
Journal Volume: 50; Journal Issue: 6; Journal ID: ISSN 0022-3727
Publisher:
IOP Publishing
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; radiation transport; photons; monte carlo; particle in cell
OSTI Identifier:
1340276
Alternate Identifier(s):
OSTI ID: 1339005