Recent progress in JT-60U experiments

Regarding JT-60U, two major objectives have been investigated: one is the confinement study and the other is the steady state physics. In the confinement study, the high βp H-mode regime was successfully obtained by controlling the heating profile. The high-energy particle-driven instability (toroidal Alfvén eigen-mode) has progressed recently. For the steady state operation, a reduction in the electromagnetic forces during disruptions is being investigated. The stored energy just before the energy quench plays an important role as regards the current quench rate. The fracture of the carbon fiber composite (CFC) first-wall tiles suggest a toroidal asymmetry of the halo current. The radiative divertor also is now being investigated.