Stability of ballooning modes in tokamaks with energetic particles
The effects of energetic particles are of interest since fast ions are present in neutral beam and rf-heated tokamaks and will occur in ignition devices in the form of alpha particles. Moreover, it may be desirable to create such particles by auxiliary heating in order to exploit their stabilizing properties and thus attain a high beta plasma. Here a range of issues related to the stabilization of MHD ballooning modes in tokamaks by using energetic particles is investigated analytically and numerically. The presence of a highly energetic plasma component can stabilize MHD ballooning modes in tokamaks and may allow direct access to the high-beta second stability regime. Here, an improved estimate of such stability was obtained, in the large-aspect-ratio circular limit, by means of a variational refinement of the lower bound for the energetic-particle potential energy. The effect of various profiles for the hot-particle pressure on stability is investigated and the stability of off-angle modes is explored. Moderately energetic particles, however, can destabilize the plasma through resonant interaction at their curvature drift frequency. Finally, even if the ideal modes and resonantly excited modes can be simultaneously stabilized, resistive ballooning instabilities may persist.
- Research Organization:
- Texas Univ., Austin (USA)
- OSTI ID:
- 6636836
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
TOKAMAK DEVICES
BALLOONING INSTABILITY
ANALYTICAL SOLUTION
ASPECT RATIO
HIGH-BETA PLASMA
MAGNETOHYDRODYNAMICS
NUMERICAL SOLUTION
STABILIZATION
CLOSED PLASMA DEVICES
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
THERMONUCLEAR DEVICES
700107* - Fusion Energy- Plasma Research- Instabilities
700101 - Fusion Energy- Plasma Research- Confinement
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