FIRST EVIDENCE OF COLLECTIVE ALPHA-PARTICLE EFFECT ON TOROIDAL ALFVENEIGENMODES IN THE TFTR D-T EXPERIMENT

The alpha particle effect on the excitation of toroidal Alfven eigenmo des (TAE) was investigated in deuterium-titrium (D-T) plasmas in the T okamak Fusion Test Reactor. rf power was used to position the plasma n ear the instability threshold, and the alpha particle effect was infer red from the reduction of rf power threshold for TAE instability in D- T plasmas. Initial calculations indicate that the alpha particles cont ribute 10%-30% of the total drive in a D-T plasma with 3 MW of peak fu sion power.