Collapse of Alfvén modes into ballooning-type modes due to toroidal nonaxisymmetry
The effect of nonaxisymmetry on Alfvén modes in toroidal geometry is investigated numerically. A model equation is used which simplifies the analysis on the resonant surfaces. Alfvén modes, characterised by their poloidal and toroidal node numbers (m, n), are found to exist in moderate nonaxisymmetry as well. For fixed (m, n), however, the mode collapses from a global feature on the resonant surface into an infinitely thin Alfvén ballooning mode along a field line if the nonaxisymmetry exceeds a critical threshold or, with given nonaxisymmetry, if the poloidal variation does so. Alfvén balloonings are polarised within the magnetic surfaces and are stable.
Bibliographic Reference: Report: IPP6/305 EN (1991) 34 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199210211 / Last updated on: 1994-12-02
Original language: en
Available languages: en