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Title: Effect of neutrals on scrape-off-layer and divertor stability in tokamaks

Abstract

The influence of ion{endash}neutral interactions (charge exchange, elastic scattering) on scrape-off-layer (SOL) stability is studied in the eikonal limit for a single-null X-point geometry typical of tokamak divertors. Instability drives due to curvature and to the ion{endash}neutral drag effect are included in the model. The ion{endash}neutral interaction terms are highly localized near the divertor plates; these terms are stabilizing for typical parameters and large enough to affect the SOL ballooning-interchange stability in the absence of resistivity. It is shown that the growth rate of ideal curvature-driven modes is significantly reduced by the ion{endash}neutral interaction terms; the growth rate of resistive ballooning modes is not affected much by the neutrals, because resistivity allows the mode to disconnect from the divertor region. In both cases, the X-point geometry significantly affects the stability. An ion{endash}neutral drag instability localized near the plates is only found in a small region of parameter space. Conditions for the existence of this instability in X-point geometry are discussed. {copyright} {ital 1999 American Institute of Physics.}

Authors:
;  [1]
  1. Lodestar Research Corporation, 2400 Central Avenue, Boulder, Colorado 80301 (United States)
Publication Date:
OSTI Identifier:
295519
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 6; Journal Issue: 2; Other Information: PBD: Feb 1999
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; PLASMA INSTABILITY; TOKAMAK DEVICES; PLASMA SCRAPE-OFF LAYER; DIVERTORS; ELASTIC SCATTERING; CHARGE EXCHANGE; BALLOONING INSTABILITY

Citation Formats

DIppolito, D A, and Myra, J R. Effect of neutrals on scrape-off-layer and divertor stability in tokamaks. United States: N. p., 1999. Web. doi:10.1063/1.873196.
DIppolito, D A, & Myra, J R. Effect of neutrals on scrape-off-layer and divertor stability in tokamaks. United States. doi:10.1063/1.873196.
DIppolito, D A, and Myra, J R. Mon . "Effect of neutrals on scrape-off-layer and divertor stability in tokamaks". United States. doi:10.1063/1.873196.
@article{osti_295519,
title = {Effect of neutrals on scrape-off-layer and divertor stability in tokamaks},
author = {DIppolito, D A and Myra, J R},
abstractNote = {The influence of ion{endash}neutral interactions (charge exchange, elastic scattering) on scrape-off-layer (SOL) stability is studied in the eikonal limit for a single-null X-point geometry typical of tokamak divertors. Instability drives due to curvature and to the ion{endash}neutral drag effect are included in the model. The ion{endash}neutral interaction terms are highly localized near the divertor plates; these terms are stabilizing for typical parameters and large enough to affect the SOL ballooning-interchange stability in the absence of resistivity. It is shown that the growth rate of ideal curvature-driven modes is significantly reduced by the ion{endash}neutral interaction terms; the growth rate of resistive ballooning modes is not affected much by the neutrals, because resistivity allows the mode to disconnect from the divertor region. In both cases, the X-point geometry significantly affects the stability. An ion{endash}neutral drag instability localized near the plates is only found in a small region of parameter space. Conditions for the existence of this instability in X-point geometry are discussed. {copyright} {ital 1999 American Institute of Physics.}},
doi = {10.1063/1.873196},
journal = {Physics of Plasmas},
number = 2,
volume = 6,
place = {United States},
year = {1999},
month = {2}
}