Tokamak equilibria with nearly zero central current; The Current hole

中心電流がほとんどゼロのトカマク平衡; 電流ホール

藤田 隆明

Fujita, Takaaki

Results of experimental and theoretical studies on the "current hole", namely nearly zero current density region in the central part of a tokamak plasma, is reviewed. The observation of stable sustainment of the current hole opened a new class of configurations in tokamak plasmas, and a variety of researches in view point of equilibrium, MHD stability, particle orbit, and radial transport has been generated. Some theories and codes have been tested and extended by being tested and applied to extreme conditions in the current hole with very weak poloidal field. Current hole is generated in high confinement plasmas with a large fraction of bootstrap current in an advanced tokamak operation. The current hole is very stiff against the current drive, which suggests that it is a highly self-regulated system. Appearance of current hole in ITER and DEMO is expected and its influence and its control methods have been studied.