NBI Beam Ion Distributions in the Presence of Magnetic Islands in Helical Plasmas

Abstract

Neutral beam injection (NBI) heating simulations of Large Helical Device (LHD) plasma in the presence of magnetic islands are performed using a drift kinetic equation solver, GNET. A magnetic perturbation that causes a magnetic island with poloidal and toroidal mode numbers (m, n) = (1, 1) is considered. It is found that the spatial distribution of beam ions for counter-tangential NBI is significantly modified near the magnetic island, exhibiting a strong dependency on the mode phase of the island. The changes in the velocity space distribution and orbits of the transition particles imply an enhancement in the ripple transport of beam ions near the magnetic island.