Estimations of Beam-Beam Fusion Reaction Rates in the Deuterium Plasma Experiment on LHD

Abstract

Beam-beam nuclear fusion reactions in the Large Helical Device (LHD) deuterium plasma are investigated by the Global NEoclassical Transport (GNET) code, which can solve the five-dimensional drift kinetic equation using Monte Carlo methods. We evaluate the velocity space distribution of the energetic deuterons to calculate the fusion reaction rates between the beams. The calculated fraction of the beam-beam contribution is approximately 1.3% in the 1 MW heating power case and 6.7% in the 5 MW case, which would not be negligible. The beam-beam fusion rate depends on the square of the beam density and on the direction of the injected beams. When both the co- and counter-tangential beams are injected simultaneously, the synergetic beam-beam reaction rates can be approximately 2.9 times larger than the co-beamline contribution alone because of an increase in the relative velocity.