CONFINED ALPHA-DISTRIBUTION MEASUREMENTS IN A DEUTERIUM-TRITIUM TOKAMAK PLASMA

Fusion-produced alpha particles with energy less than or equal to 0.7 MeV have been spectroscopically observed in the core of a deuterium-tr itium plasma in the TFTR tokamak at alpha densities of 3 x 10(16) m(-3 ). During a sawtooth-free discharge, the measured energy spectra at r/ a = 0.3 are in good agreement with those predicted on the basis of col lisional transport. Time-resolved measurements during the alpha therma lization after alpha source turn-off show decay of the distribution fu nction to lower energies consistent with the classical slowing-down ti me of 0.5 s.