Thermally driven convective cells and tokamak edge turbulence
作者:
D. R. Thayer,
P. H. Diamond,
期刊:
Physics of Fluids(00319171)
(AIP Available online 1987)
卷期:
Volume 30,
issue 12
页码: 3724-3734
ISSN:0031-9171
年代: 1987
DOI:10.1063/1.866409
出版商: AIP
数据来源: AIP
摘要:
A unified theory for the dynamics of thermally driven convective cell turbulence is presented. The cells are excited by the combined effects of radiative cooling and resistivity gradient drive. The model also includes impurity dynamics. Parallel thermal and impurity flows enhanced by turbulent radial diffusion regulate and saturate overlapping cells, even in regimes dominated by thermal instability. Transport coefficients and fluctuation levels characteristic of the saturated turbulence are calculated. It is found that the impurity radiation increases transport coefficients for high density plasmas, while the parallel conduction damping, elevated by radial diffusion, in turn quenches the thermal instability. The enhancement due to radiative cooling provides a resolution to the dilemma of explaining the experimental observation that potential fluctuations exceed density fluctuations in the edge plasma (e&Fgr;/Te>n/n0).
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