Abstract
The Lausanne ideal MHD stability code ERATO is used to investigate spectral properties of Solovèv's equilibrium at small aspect ratios. Two different elongations are considered. Both free and rigid boundary models are computed and compared. Modes characterized by a large radial extension have been found which appear to be due to a coupling ofm=1 andm=2 modes due to toricity. The internal modes spectrum is compared with the predictions of the full mercier criterion, taking into account its spatial dependence, and with the ballooning modes stability criterion.
Résumé
Les propriétés spectrales des équilibres analytiques de Solov'èv à petit rapport d'aspect sont étudiées à l'aide du code numérique ERATO qui permet de calculer le spectre magnétohydrodynamique d'une configuration Tokomak quelconque. Nous avons examiné deux situations différentes: paroi conductrice collée contre la surface du plasma et vide infini ainsi que deux élongations. Nous avons trouvé que les modes instables ont une grande extension radiale, due au couplage torique entre les modesm=1 etm=2. Le spectre des modes internes est comparé aux prédictions du critère de Mercier, prenant en considération sa dépendance radiale. La limite de stabilité aux modes internes à basn est comprise entre la limite de Mercier correspondante et la limite ballooning.
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Presently at IBM Lausanne.
Presently at General Atomics, San Diego.
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Berger, D., Bernard, L.C., Gruber, R. et al. Numerical study of the unstable MHD spectrum of a small aspect ratio, flat current, non-circular tokamak. Journal of Applied Mathematics and Physics (ZAMP) 31, 113–132 (1980). https://doi.org/10.1007/BF01601708
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DOI: https://doi.org/10.1007/BF01601708