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Plasma stability theory including the resistive wall effects

Part of: Focus on Fusion

Published online by Cambridge University Press:  09 December 2015

V. D. Pustovitov
V. D. Pustovitov*
Affiliation:
National Research Centre ‘Kurchatov Institute’, Kurchatov Sq., 1, Moscow 123182, Russian Federation National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow 115409, Russian Federation
*
†Email address for correspondence: Pustovitov_VD@nrcki.ru
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Abstract

Plasma stabilization due to a nearby conducting wall can provide access to better performance in some scenarios in tokamaks. This was proved by experiments with an essential gain in ${\it\beta}$ and demonstrated as a long-lasting effect at sufficiently fast plasma rotation in the DIII-D tokamak (see, for example, Strait et al., Nucl. Fusion, vol. 43, 2003, pp. 430–440). The rotational stabilization is the central topic of this review, though eventually the mode rotation gains significance. The analysis is based on the first-principle equations describing the energy balance with dissipation in the resistive wall. The method emphasizes derivation of the dispersion relations for the modes which are faster than the conventional resistive wall modes, but slower than the ideal magnetohydrodynamics modes. Both the standard thin wall and ideal-wall approximations are not valid in this range. Here, these are replaced by an approach incorporating the skin effect in the wall. This new element in the stability theory makes the energy sink a nonlinear function of the complex growth rate. An important consequence is that a mode rotating above a critical level can provide a damping effect sufficient for instability suppression. Estimates are given and applications are discussed.

Type
Research Article
Information
Journal of Plasma Physics , Volume 81 , Issue 6 , December 2015 , 905810609
Copyright
© Cambridge University Press 2015 

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