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

This paper reports first observations in a tokamak plasma of MeV energy ions produced by close elastic collisions (knock-on) between deuterium–tritium fusion α-particles and thermal plasma fuel ions. Measurements of flux of MeV energy helium and deuterium atoms from the plasma in the Joint European Torus [P.-H. Rebut, A. Gibson, M. Huget et al., Nucl. Fusion 32, 187 (1992)] were made from which line-integrated energy distribution function of knock-on deuterons, F̄d(E), was deduced. Neutralization of the deuterons and α-particles was effected by charge-exchange with one- and two-electron species of the main intrinsic plasma impurities, carbon, beryllium, and helium. Deduced F̄d(E) is shown to be in agreement with calculations using classical confinement and slowing-down of fusion α-particles and knock-on deuterons.