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Destabilization of TAE modes by particle anisotropy

1999; Elsevier BV; Volume: 251; Issue: 2 Linguagem: Inglês

10.1016/s0375-9601(98)00866-4

1873-2429

H. Vernon Wong, H. L. Berk,

Solar and Space Plasma Dynamics

Plasmas heated by ICRF produce energetic particle distribution functions which are sharply peaked in pitch-angle, and we show that at moderate toroidal mode numbers, this anisotropy is a competitive and even dominant instability drive when compared with the universal instability drive due to spatial gradient.The universal drive, acting alone.destabilizes only co-propagating waves (i.e.waves propagating in the same toroidal direction as the diamagnetic flow of the energetic particles), but stabilizes counter-propagating waves (i.e.waves propagating in the opposite toroidal direction as the diamagnetic flow of the energetic particles).Nonetheless, we show that in a tokamak, it is possible that particle anisotropy can produce a larger linear growth rate for counter-propagating waves, and provide a mechanism for preferred destabilization of the counter-propagating TAE modes that are sometimes experimentally observed.