TOROIDAL ALFVEN EIGENMODES IN TFTR DEUTERIUM-TRITIUM PLASMAS

Purely alpha-particle-driven toroidal Alfven eigenmodes (TAEs) with to roidal mode numbers n = 1-6 have been observed in deuterium-tritium (D -T) plasmas on the tokamak fusion test reactor [D. J. Grove and D. M. Meade, Nucl. Fusion 25, 1167 (1985)]. The appearance of mode activity following termination of neutral beam injection in plasmas with q(0)>1 is generally consistent with theoretical predictions of TAE stability [G. Y. Fu et al. Phys. Plasmas 3, 4036 (1996)]. Internal reflectomete r measurements of TAE activity is compared with theoretical calculatio ns of the radial mode structure. Core localization of the modes to the region of reduced central magnetic shear is confirmed, however the mo de structure can deviate significantly from theoretical estimates. The peak measured TAE amplitude of delta n/n similar to 10(-4) at r/a sim ilar to 0.3-0.4 corresponds to delta B/B similar to 10(-5), while delt a B/B similar to 10(-8) is measured at the plasma edge. Enhanced alpha particle lass associated with TAE activity has not been observed. (C) 1998 American Institute of Physics.