Study of α-particle confinement in an LHD-type heliotron reactor

Confinement of ? particles is investigated in heliotron-type reactors extending the current Large Helical Device (LHD) magnetic configurations. The GNET (Global NEoclassical Transport) code is used to study ?-particle confinement including energy slow-down and scattering of energy and pitch angle. It is found that the energy loss rate is reduced from 29% to 5% due to the improvement of the trapped particle orbit in the inward-shifted magnetic configurations. The density dependences of the ?-particle confinement is also investigated to make the possibility of a high-density heliotron-type reactor clear. It is found that the energy loss rate depends strongly on the plasma density and reaches almost 0% at a high density near 5???1020?m?3 in the inward-shifted configurations.