A singular finite element technique for calculating continuum damping of Alfvén eigenmodes
Date
2015-02-06
Authors
Bowden, G. W.
Hole, M. J.
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Publisher
American Institute of Physics
Abstract
Damping due to continuum resonances can be calculated using dissipation-less ideal magnetohydrodynamics provided that the poles due to these resonances are properly treated. We describe a singular finite element technique for calculating the continuum damping of Alfvén waves. A Frobenius expansion is used to determine appropriate finite element basis functions on an inner region surrounding a pole due to the continuum resonance. The location of the pole due to the continuum resonance and mode frequency is calculated iteratively using a Galerkin method. This method is used to find the complex frequency and mode structure of a toroidicity-induced Alfvén eigenmode in a large aspect ratio circular tokamak and is shown to agree closely with a complex contour technique.
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Source
Physics of Plasmas
Type
Journal article