Magnetohydrodynamic waves and instabilities in rotating tokamak plasmas

Research output: ThesisDissertation (external)

Abstract

One of the most promising ways to achieve controlled nuclear fusion
for the commercial production of energy is the tokamak design. In
such a device, a hot plasma is confined in a toroidal geometry using
magnetic fields. The present generation of tokamaks shows significant
plasma rotation, primarily in the toroidal direction. This plasma
flow has an important impact on stability and confinement, aspects of
which can be described quite well by the theory of magnetohydrodynamics
(MHD).
This work contains a comprehensive theoretical analysis,
supported by numerical simulations, of the MHD equilibrium, waves,
and instabilities of rotating tokamak plasmas. A new general description
of the thermodynamic state of the equilibrium is presented. Next,
a stability criterion is derived that generalizes various previous results
by including toroidal rotation. This criterion shows that a radially decreasing
rotation profile can be stabilizing. The previously unknown
origin of this stabilization is shown to be the Coriolis effect, with a mediating
role for the pressure. Various factors that affect stability also
influence stable waves and eigenmodes of the plasma. New modes
that are created by rotation are found, and the effect of rotation on a
type of experimentally well-known modes is described.
Finally, the step to nonlinear magnetohydrodynamics is made
by extending an existing reduced MHD code to the full viscoresistive
MHD equations. This allows a study of the nonlinear evolution of the
equilibria, waves, and instabilities described in this thesis.
Original languageEnglish
Publication statusPublished - 21 Mar 2013
Externally publishedYes

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