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Title: Kinetic simulations of gas breakdown in the dense plasma focus

We describe the first fully-kinetic, collisional, and electromagnetic simulations of the breakdown phase of a MA-scale dense plasma focus and are shown to agree with measured electrical characteristics, including breakdown time. In the model, avalanche ionization is driven by cathode electron emission and this results in incomplete gas breakdown along the insulator. This reinforces the importance of the conditioning process that creates a metallic layer on the insulator surface. The simulations, nonetheless, help explain the relationship between the gas pressure, the insulator length, and the coaxial gap width. In the past, researchers noted three breakdown patterns related to pressure. Simulation and analytic results show that at low pressures, long ionization path lengths lead to volumetric breakdown, while high pressures lead to breakdown across the relatively small coaxial electrode gap. In an intermediate pressure regime, ionization path lengths are comparable to the insulator length which promotes ideal breakdown along the insulator surface.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [2] ;  [1] ;  [3]
  1. National Security Technologies, LLC. (NSTec), Las Vegas, NV (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Voss Scientific, Inc., Albuquerque, NM (United States)
Publication Date:
Grant/Contract Number:
AC52-06NA25946
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
National Security Technologies, LLC. (NSTec), Las Vegas, NV (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Insulators; Dense plasma focusIonization; Cathodes; Plasma sheaths
OSTI Identifier:
1363871
Alternate Identifier(s):
OSTI ID: 1366568