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Abstract

The ideal stability of cylindrical plasma with mass flows is investigated using the guiding centre plasma (GCP) model of Grad. For rotating plasmas, the kinetic treatment of the parallel motion in GCP gives significantly different results from the fluid models, where the pressures are obtained from equations of state. In particular, GCP removes the resonance with slow magnetoacoustic waves and the loss of stability that occurs in magnetohydrodynamics (MHD) for near-sonic flows. Because of the strong kinetic damping of the sound waves in an isothermal plasma, the slow waves have little influence on plasma stability in GCP at low beta. In the large aspect ratio, low-beta tokamak ordering, Alfvènic flows are needed to change the ideal GCP stability significantly. At lowest order in the inverse aspect ratio, flow can be favourable or unfavourable for stability of local modes depending on the profiles, but external kinks are always destabilized by flow if the velocity vanishes at the edge. For high-beta, reversed field pinch equilibria, numerical computations show that flow can be stabilizing for local modes, but external modes are destabilized by flow. In three dimensions, the MHD equilibrium problem becomes hyperbolic for arbitrarily small flows across the magnetic field, whereas the GCP equilibrium equation remains elliptic for sub-Alfvènic flows.

Additional information

Authors: BONDESON A, Centre de Recherches en Physique des Plasmas, École Polytechnique Fédérale de Lausanne, 21, avenue des Bains, CH-1007 Lausanne (CH);IACONO R, Centre de Recherches en Physique des Plasmas, École Polytechnique Fédérale de Lausanne, 21, avenue des Bains, CH-1007 Lausanne (CH)
Bibliographic Reference: Paper presented: International Sherwood Theory Meeting, University of Texas, San Antonia, Texas, United States, April 3-5, 1989 Article: Phys. Fluids. Vol. 1 (1989), No. 7, pp. 1431-1443
Availability: Available from (1) as Paper EN 34609 ORA
Record Number: 198911085 / Last updated on: 1994-12-01
Category: PUBLICATION
Original language: en
Available languages: en
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