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Title: Return current instability driven by a temperature gradient in ICF plasmas

Here, hot plasmas with strong temperature gradients in inertial confinement fusion (ICF) experiments are examined for ion acoustic instabilities produced by electron heat flow. The return current instability (RCI) due to a neutralizing current of cold electrons arising in response to a large electron heat flux has been considered. First, the linear threshold and growth rates are derived in the nonlocal regime of thermal transport. They are compared with the results of Vlasov-Fokker-Planck (VFP) simulations in one spatial dimension. Very good agreement has been found between kinetic VFP simulations and the linear theory of the RCI. A quasi-stationary state of ion acoustic turbulence produced by the RCI is achieved in the VFP simulations. Saturation of the RCI involves heating of ions in the tail of the ion distribution function and convection of the enhanced ion acoustic fluctuations from the unstable region of the plasma. Further evolution of the ion acoustic turbulence and its effects on absorption and transport are also discussed.
Authors:
 [1] ;  [2] ;  [3] ;  [2]
  1. Univ. of Alberta, Edmonton, AB (Canada)
  2. Russian Academy of Science, Moscow (Russia)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-PROC-737115
Journal ID: ISSN 0741-3335
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 1; Conference: Presented at: European Physical Society Plasma Physics, Belfast (United Kingdom), 26-30 Jun 2017; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United Kingdom)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; return current instability; ion acoustic turbulence; anomalous absorption and transport
OSTI Identifier:
1393332