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Title: Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation

Abstract

Parallel transport of long mean-free-path plasma along an open magnetic field line is characterized by strong temperature anisotropy, which is driven by two effects. The first is magnetic moment conservation in a non-uniform magnetic field, which can transfer energy between parallel and perpendicular degrees of freedom. The second is decompressional cooling of the parallel temperature due to parallel flow acceleration by conventional presheath electric field which is associated with the sheath condition near the wall surface where the open magnetic field line intercepts the discharge chamber. To the leading order in gyroradius to system gradient length scale expansion, the parallel transport can be understood via the Chew-Goldbeger-Low (CGL) model which retains two components of the parallel heat flux, i.e., q{sub n} associated with the parallel thermal energy and q{sub s} related to perpendicular thermal energy. It is shown that in addition to the effect of magnetic field strength (B) modulation, the two components (q{sub n} and q{sub s}) of the parallel heat flux play decisive roles in the parallel variation of the plasma profile, which includes the plasma density (n), parallel flow (u), parallel and perpendicular temperatures (T{sub Parallel-To} and T{sub Up-Tack }), and the ambipolar potential ({phi}). Both theirmore » profile (q{sub n}/B and q{sub s}/B{sup 2}) and the upstream values of the ratio of the conductive and convective thermal flux (q{sub n}/nuT{sub Parallel-To} and q{sub s}/nuT{sub Up-Tack }) provide the controlling physics, in addition to B modulation. The physics described by the CGL model are contrasted with those of the double-adiabatic laws and further elucidated by comparison with the first-principles kinetic simulation for a specific but representative flux expander case.« less

Authors:
;  [1]
  1. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
22086020
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 19; Journal Issue: 8; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ADIABATIC PROCESSES; ANISOTROPY; DEGREES OF FREEDOM; ELECTRIC DISCHARGES; ELECTRIC FIELDS; HEAT FLUX; MAGNETIC FIELDS; MAGNETIC MOMENTS; MEAN FREE PATH; MODULATION; PLASMA DENSITY; PLASMA RADIAL PROFILES; PLASMA SIMULATION; POTENTIALS

Citation Formats

Zehua, Guo, and Xianzhu, Tang. Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation. United States: N. p., 2012. Web. doi:10.1063/1.4747167.
Zehua, Guo, & Xianzhu, Tang. Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation. United States. https://doi.org/10.1063/1.4747167
Zehua, Guo, and Xianzhu, Tang. Wed . "Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation". United States. https://doi.org/10.1063/1.4747167.
@article{osti_22086020,
title = {Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation},
author = {Zehua, Guo and Xianzhu, Tang},
abstractNote = {Parallel transport of long mean-free-path plasma along an open magnetic field line is characterized by strong temperature anisotropy, which is driven by two effects. The first is magnetic moment conservation in a non-uniform magnetic field, which can transfer energy between parallel and perpendicular degrees of freedom. The second is decompressional cooling of the parallel temperature due to parallel flow acceleration by conventional presheath electric field which is associated with the sheath condition near the wall surface where the open magnetic field line intercepts the discharge chamber. To the leading order in gyroradius to system gradient length scale expansion, the parallel transport can be understood via the Chew-Goldbeger-Low (CGL) model which retains two components of the parallel heat flux, i.e., q{sub n} associated with the parallel thermal energy and q{sub s} related to perpendicular thermal energy. It is shown that in addition to the effect of magnetic field strength (B) modulation, the two components (q{sub n} and q{sub s}) of the parallel heat flux play decisive roles in the parallel variation of the plasma profile, which includes the plasma density (n), parallel flow (u), parallel and perpendicular temperatures (T{sub Parallel-To} and T{sub Up-Tack }), and the ambipolar potential ({phi}). Both their profile (q{sub n}/B and q{sub s}/B{sup 2}) and the upstream values of the ratio of the conductive and convective thermal flux (q{sub n}/nuT{sub Parallel-To} and q{sub s}/nuT{sub Up-Tack }) provide the controlling physics, in addition to B modulation. The physics described by the CGL model are contrasted with those of the double-adiabatic laws and further elucidated by comparison with the first-principles kinetic simulation for a specific but representative flux expander case.},
doi = {10.1063/1.4747167},
url = {https://www.osti.gov/biblio/22086020}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 8,
volume = 19,
place = {United States},
year = {2012},
month = {8}
}