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Title: A short mean-free path, coupled neutral-ion transport description of a tokamak edge plasma

Abstract

The ion and neutral densities and temperatures in the edge region of a diverted plasma can vary over two or more orders of magnitude causing atomic physics processes to modify the usual short mean-free path transport descriptions of magnetized plasmas. The short-mean-free path ordering is particularly relevant to the rather cold, moderately dense plasmas of interest in gas target divertor operation. Under such conditions, charge-exchange, ionization, and recombination couple the ions to the neutrals and alter the transport coefficients of both species. The coupling modifications to the ions are evaluated in the short mean-free path limit by a minor adjustment in standard procedures when neutral--neutral collisions are negligible. The short-mean-free path coupling modifications to the neutrals are evaluated by assuming the charge-exchange rate coefficient is velocity independent. A closed neutral-ion fluid description is obtained by assuming temperatures sufficiently high that ion energy and momentum exchange with the electrons is unaffected by atomic processes and densities sufficiently low that electron--neutral collisions may be neglected.

Authors:
 [1]
  1. Massachusetts Institute of Technology, Plasma Fusion Center, 167 Albany Street, NW16-236, Cambridge, Massachusetts 02139 (United States)
Publication Date:
OSTI Identifier:
7270405
DOE Contract Number:  
FG02-91ER54109
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas; (United States)
Additional Journal Information:
Journal Volume: 1:6; Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA; KINETIC EQUATIONS; TOKAMAK DEVICES; ION DRIFT; CHARGE EXCHANGE; ION-ATOM COLLISIONS; IONIZATION; MEAN FREE PATH; NEUTRAL-PARTICLE TRANSPORT; RECOMBINATION; ATOM COLLISIONS; CLOSED PLASMA DEVICES; COLLISIONS; EQUATIONS; ION COLLISIONS; RADIATION TRANSPORT; THERMONUCLEAR DEVICES; 700330* - Plasma Kinetics, Transport, & Impurities- (1992-)

Citation Formats

Catto, P J. A short mean-free path, coupled neutral-ion transport description of a tokamak edge plasma. United States: N. p., 1994. Web. doi:10.1063/1.870649.
Catto, P J. A short mean-free path, coupled neutral-ion transport description of a tokamak edge plasma. United States. doi:10.1063/1.870649.
Catto, P J. Wed . "A short mean-free path, coupled neutral-ion transport description of a tokamak edge plasma". United States. doi:10.1063/1.870649.
@article{osti_7270405,
title = {A short mean-free path, coupled neutral-ion transport description of a tokamak edge plasma},
author = {Catto, P J},
abstractNote = {The ion and neutral densities and temperatures in the edge region of a diverted plasma can vary over two or more orders of magnitude causing atomic physics processes to modify the usual short mean-free path transport descriptions of magnetized plasmas. The short-mean-free path ordering is particularly relevant to the rather cold, moderately dense plasmas of interest in gas target divertor operation. Under such conditions, charge-exchange, ionization, and recombination couple the ions to the neutrals and alter the transport coefficients of both species. The coupling modifications to the ions are evaluated in the short mean-free path limit by a minor adjustment in standard procedures when neutral--neutral collisions are negligible. The short-mean-free path coupling modifications to the neutrals are evaluated by assuming the charge-exchange rate coefficient is velocity independent. A closed neutral-ion fluid description is obtained by assuming temperatures sufficiently high that ion energy and momentum exchange with the electrons is unaffected by atomic processes and densities sufficiently low that electron--neutral collisions may be neglected.},
doi = {10.1063/1.870649},
journal = {Physics of Plasmas; (United States)},
issn = {1070-664X},
number = ,
volume = 1:6,
place = {United States},
year = {1994},
month = {6}
}