Toroidally localized and nonlocalized ballooning instabilities in a stellarator

It is shown that the coexistence of toroidally nonlocalized ideal-hydromagnetic ballooning instabilities, with a quasidiscrete spectrum, and toroidally localized ballooning instabilities with a broad continuous spectrum, as predicted by Dewar and Glasser [Phys. Fluids 26, 3038 (1983)] can be realized in a Mercier-unstable equilibrium case modeling the Large Helical Device (LHD) [A. Iiyoshi et al., Fusion Technol. 17, 148 (1990)] with a broad pressure profile. The quasidiscrete, interchange branch corresponds to extended modes that can be understood on the basis of a ripple-averaged ballooning equation, whereas the broad-continuum, ballooning branch corresponds to modes localized along a flux tube, The physical origin of the two branches is discussed. (C) 1998 American Institute of Physics.


Published in:
Physics of Plasmas, 5, 8, 2921-2931
Year:
1998
ISSN:
1070-664X
ISBN:
1070-664X
Laboratories:
SPC
CRPP




 Record created 2008-04-16, last modified 2018-01-28


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