Observation of MeV energy deuterons produced by knock-on collisions between deuterium-tritium fusion alpha-particles and plasma fuel ions

This paper reports first observations in a tokamak plasma of MeV energy ion s produced by close elastic collisions (knock-on) between deuterium-tritium fusion alpha-particles and thermal plasma fuel ions. Measurements of flux of MeV energy helium and deuterium atoms from the plasma in the Joint Europ ean Torus [P.-H. Rebut, A. Gibson, M. Huget , Nucl. Fusion 32, 187 (1992)] were made from which line-integrated energy distribution function of knock- on deuterons, (F) over bar(d)(E), was deduced. Neutralization of the deuter ons and alpha-particles was effected by charge-exchange with one- and two-e lectron species of the main intrinsic plasma impurities, carbon, beryllium, and helium. Deduced (F) over bar(d)(E) is shown to be in agreement with ca lculations using classical confinement and slowing-down of fusion alpha-par ticles and knock-on deuterons. (C) 2000 American Institute of Physics. [S10 70-664X(00)00503-6].