n-dependence of ballooning instabilities

The critical beta for stability against ideal hydromagnetic internal ballooning modes as a function of the toroidal mode number, n, is calculated for two different equilibrium sequences by use of a finite-element technique (n less than approximately 20), and a WKB formalism (n greater than approxima...

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Bibliographic Details
Published inNuclear fusion Vol. 21; no. 4; pp. 493 - 498
Main Authors Dewar, R.L, Manickam, J, Grimm, R.C, Chance, M.S
Format Journal Article
LanguageEnglish
Published IOP Publishing 01.04.1981
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Summary:The critical beta for stability against ideal hydromagnetic internal ballooning modes as a function of the toroidal mode number, n, is calculated for two different equilibrium sequences by use of a finite-element technique (n less than approximately 20), and a WKB formalism (n greater than approximately 5). The agreement between the two methods is good in the overlap region n between 5 and 20. The WKB formula reduces to the 1/n correction at very high n, but is much more accurate at moderate n. The critical-beta-versus-n curves exhibit oscillatory structure at low n, but in both sequences the lower bound on the critical beta is set by n = infinity modes at critical beta of about 5%.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0029-5515
1741-4326
DOI:10.1088/0029-5515/21/4/008