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: IAEA, 1990) 9) at magnetic fields above 10 kG. These involved pellet injection to raise the plasma density, variation of the plasma current to change the energetic ion orbit and the q-profile, and ICRF heating to produce energetic hydrogen ions at velocities comparable with 3.5 MeV alpha particles created in deuterium-tritium (d-t) fusion reactions. The amplitude of the TAE modes observed in ICRF-heated plasmas behaves differently from those driven by neutral beams. This can be explained by the difference in the energetic ion orbits. These experimental results are presented and relevance to fusion reactors are discussed.