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Ion kinetic effects on linear pressure driven magnetohydrodynamic instabilities in helical plasmas

Part of: Focus on Fusion

Published online by Cambridge University Press:  11 June 2020

M. Sato Open the ORCID record for M. Sato [Opens in a new window]  and
Y. Todo Open the ORCID record for Y. Todo [Opens in a new window]
M. Sato*
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki, Gifu509-5292, Japan
Y. Todo
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi, Toki, Gifu509-5292, Japan
*
†Email address for correspondence: masahiko@nifs.ac.jp
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Abstract

The linear MHD (magnetohydrodynamic) stability for high beta plasmas in the inward shifted Large Helical Device (LHD) configurations has been investigated for a wide range of magnetic Reynolds numbers $S$ using numerical simulations based on the kinetic MHD model with kinetic thermal ions where the beta is the ratio of the plasma pressure to the magnetic pressure. It is found that the dependence of the linear growth rate of the resistive ballooning modes on the $S$ number changes from $\unicode[STIX]{x1D6FE}\propto S^{-1/3}$ to $\unicode[STIX]{x1D6FE}\propto S^{-1}$ by the kinetic thermal ion effects so that the resistive ballooning modes are significantly suppressed as the $S$ number increases. For a high $S$ number comparable to experimental values, the most unstable modes are interchange modes. The kinetic thermal ion effects change the most unstable interchange mode from the ideal mode to the resistive mode. This transition of the interchange modes by kinetic thermal ion effects is consistent with the shift of the marginal stability boundary for the ideal interchange modes observed in the LHD experiments.

Keywords

plasma confinementplasma simulation
Type
Research Article
Information
Journal of Plasma Physics , Volume 86 , Issue 3 , June 2020 , 815860305
Copyright
© The Author(s), 2020. Published by Cambridge University Press

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