球状トカマクの実用炉への展望 -トカマクの低アスペクト比化への挑戦- 3.高閉じ込めは高ベータと両立するか? 3.2 低アスペクト比トカマク炉のアルファ粒子閉じ込め

Studies were made on ripple losses of fusion produced alpha particles in a low-aspect-ratio tokamak reactor (VECTOR) by using an orbit-following Monte-Carlo code. Alpha particles are well confined in VECTOR. In a low-aspect-ratio tokamak, the dependence of ripple losses on the number of toroidal-field (TF) coils N is very weak. Assuming a toroidal peaking factor of 2 for the heat load due to loss particles, about 1.5% and 1.0% of TF ripple at the outer edge of plasma might be allowable for the first wall with and without cooling system, respectively. In both cases, the number of TF-coils can be reduced to about 4.