Excitation of Alfven Modes by Energetic Particles in Magnetic Fusion
Authors: N.N. Gorelenkov
Abstract: Ions with energies above the plasma ion temperature (also called super thermal,
hot or energetic particles - EP) are utilized in laboratory experiments as a plasma
heat source to compensate for energy loss. Sources for super thermal ions are direct injection
via neutral beams, RF heating and fusion reactions. Being super thermal, ions have
the potential to induce instabilities of a certain class of magnetohydrodynamics (MHD)
cavity modes, in particular, various Alfven and Alfven-acoustic Eigenmodes. It is an area
where ideal MHD and kinetic theories can be tested with great accuracy. This paper
touches upon key motivations to study the energetic ion interactions with MHD modes.
One is the possibility of controlling the heating channel of present and future tokamak
reactors via EP transport. In some extreme circumstances, uncontrolled instabilities led
to vessel wall damages. This paper reviews some experimental and theoretical advances
and the developments of the predictive tools in the area of EP wave interactions. Some
recent important results and challenges are discussed. Many predicted instabilities pose a
challenge for ITER, where the alpha-particle population is likely to excite various modes.
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Submitted to: International ITER Summer School Aux Provence, France (June 2011)
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Download PPPL-4715 (pdf 6696 KB 15 pp)
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