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Stability of a tokamak plasma with diffuse toroidal rotation

Part of: Focus on Fusion

Published online by Cambridge University Press:  20 October 2020

O. E. López Open the ORCID record for O. E. López [Opens in a new window]  and
L. Guazzotto Open the ORCID record for L. Guazzotto [Opens in a new window]
O. E. López*
Affiliation:
Physics Department, Auburn University, Auburn, AL36849, USA
L. Guazzotto
Affiliation:
Physics Department, Auburn University, Auburn, AL36849, USA
*
†Email address for correspondence: [email protected]
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Abstract

The present work considers the stability of a high-$\beta$, large aspect ratio, circular plasma with diffuse profiles for the safety factor and the angular toroidal frequency (López & Guazzotto, Phys. Plasmas, vol. 24, 032501). An application of the Frieman–Rotenberg formalism results in a system of scalar eigenmode equations whose coupling is retained at the plasma–vacuum transition but is disregarded across the plasma column, which is a standard practice. The solution technique consists of a multidimensional shooting method for the poloidal harmonics; robust initial guesses are constructed by solving the dispersion relation in the static scenario with vanishing magnetic shear. Flow shear appears as a high-$\beta$ toroidal contribution, and we illustrate its destabilizing influence on $n=1$ external kink modes in the presence of ideal and resistive walls. Internal resonances are avoided by means of the selection of appropriate equilibrium parameters. The stabilizing influence of a finite positive average magnetic shear is also exemplified.

Keywords

plasma flowsfusion plasmaplasma instabilities
Type
Research Article
Information
Journal of Plasma Physics , Volume 86 , Issue 5 , October 2020 , 905860514
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Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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References

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