Advanced tokamak research on JT-60

The Japanese large tokamak JT-60 has been focusing its research emphasis on the development of high performance plasmas, with high confinement, high temperature and high density and non-inductive sustainment for a long time with possible minimization of external power input. The first demonstration of high bootstrap current discharges up to 80% of the total plasma current in a high-poloidal-beta (high-βp) mode and the concept development of a steady-state tokamak reactor (SSTR) based on this experimental achievement initiated the so-called 'advanced tokamak research'. The internal transport barriers (ITBs), discovered in the JT-60 high-βp mode, have been followed by worldwide explorations of reversed shear discharges associated with ITBs. The highest DT equivalent energy gain of was achieved in the JT-60 reversed shear H-mode discharges. The highest ion temperature of Ti = 45 keV and the highest fusion triple product of ni(0)τETi(0) = 1.5 × 1021 m−3 s keV were obtained in high-βp discharges. Advanced tokamak research is now the major trend of the current tokamak development. A new concept of compact ITER has been developed and proposed in the context of this advanced tokamak approach pursued on JT-60. Prospects for burning plasma physics have been investigated along the progress made in these modern tokamak experiments on JT-60 and related computer simulation analyses.