EXPANSION OF PARAMETER SPACE FOR TOROIDAL ALFVEN EIGENMODE EXPERIMENTS IN TFTR

Several techniques were used to excite toroidal Alfven eigenmodes (TAE ) in the Tokamak Fusion Test Reactor (TFTR) (Proc. 13th Int. Conf. on Plasma Physics and Controlled Nuclear Fusion Research Vol 1 (Vienna: I AEA, 1990) 9) at magnetic fields above 10 kG. These involved pellet in jection to raise the plasma density, variation of the plasma current t o change the energetic ion orbit and the q-profile. and ICRF heating t o produce energetic hydrogen ions al velocities comparable with 3.5 Me V alpha particles created in deuterium-tritium (d-t) fusion reactions. The amplitude of the TAE modes observed in ICRF-heated plasmas behave s differently from those driven bv neutral beams. This can be explaine d by the difference in the energetic ion orbits. These experimental re sults are presented and relevance to fusion reactors are discussed.