Title: 1D PIC-DSMC analysis of a high-pressure nanosecond pulse discharge breakdown in helium

Abstract

Kinetic simulations of plasma phenomena during and after formation of the conductive plasma channel of a nanosecond pulse discharge are analyzed and compared to existing experimental measurements. Particle-in-cell with direct simulation Monte Carlo collisions (PIC-DSMC) modeling is used to analyze a discharge in helium at 200 Torr and 300 K over a 1 cm gap. The analysis focuses on physics that would not be reproduced by fluid models commonly used at this high number density and collisionality, specifically non-local and stochastic phenomena. Similar analysis could be used to improve the predictive capability of lower fidelity or reduced order models. First, the modeling results compare favorably with experimental measurements of electron number density, temperature, and 1D electron energy distribution function at the same conditions. Second, it is shown that the ionization wave propagates in a stochastic, stepwise manner, dependent on rare, random ionization events ahead of the ionization wave when the ionization fraction in front of the ionization wave is very low, analagous to the stochastic branching of streamers in 3D. Third, analysis shows high-energy runaway electrons accelerated in the cathode layer produce electron densities in the negative glow region over an order of magnitude above those in the positive column.more » Finally, future work to develop reduced order models of these two phenomena would improve the accuracy of fluid plasma models without the cost of PIC-DSMC simulations.« less

Authors:

Eckert, Zakari  ^[1];

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Boerner, Jeremiah J. ^[1]; Grillet, Anne M. ^[1]

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+ Show Author Affiliations

1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Publication Date:

2019-11-07

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1574487

Report Number(s):

SAND2019-13505J
Journal ID: ISSN 0022-3727; 681175

Grant/Contract Number:  

AC04-94AL85000; NA000352; NA0002374

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physics. D, Applied Physics

Additional Journal Information:

Journal Volume: 53; Journal Issue: 3; Journal ID: ISSN 0022-3727

Publisher:

IOP Publishing

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS