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Applied Plasma Physics and Fusion Energy Seminar Series

Fall 2002

Tuesday, 3:30-4:30 PM in 479 EBU-II


October 29

An overview of fast particle physics in MFE devices
Prof. William Heidbrink
UC Irvine

ABSTRACT:

Suprathermal ions with energies much greater than the thermal ions and electrons are commonplace in magnetic fusion devices. Sources of fast ions include fusion reactions, neutral-beam heating, and radio-frequency heating in the ion cyclotron range of frequencies. For dilute populations, Coulomb scattering theory accurately describes thermalization. The basic confinement properties in the absence of fluctuating fields are well understood in tokamaks; in configurations where the orbital invariants are broken the confinement properties are an active area of research. In tokamaks, fast-ion transport due to micro-turbulence is much smaller than typical thermal transport rates. On the other hand, field distortions associated with large-scale MHD activity often cause large losses. When the fast-ion pressure is large, fast ions can drive instabilities through wave-particle resonances. One class of instabilities, such as the various Alfven gap modes, are weakly-damped normal modes of the background plasma. Another class of waves known as Energetic Particle Modes rely on the fast-ion population for their existence.

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