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Author(s):
N. Nakajima
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Title:
Three Dimensional Ideal MHD Stability Analysis in L=2 Heliotron Systems
Date of publication:
Oct. 2000
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Key words:
IAEA, fusion energy conference, Sorrento
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Abstract:
Global mode analyses of ideal MHD instability are performed under both fixed and free boundary conditions for L/M = 2/10 heliotron configurations, where L and M are the polarity and toroidal field period of helical coils, respectively. Under the fixed boundary condition, dangerous low-n ballooning modes with n < M (n is a typical toroidal mode number) are not destabilized, when the pressure gradient almost vanishes near plasma periphery. However, such ballooning modes and/or peeling modes are destabilized under the free boundary condition even for the currentless condition, when a steep pressure gradient exists near the plasma boundary. Effects of the net toroidal current on the external modes are also discussed.
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