Stationary high confinement plasmas with large bootstrap current fraction in JT-60U

Full text: Recent experiments on the JT-60U tokamak have achieved long sustainment of a large noninductive current drive fraction (>90%) with a large bootstrap current fraction (∼75%) for 7.4 s (>current relaxation time) in a reversed shear plasma with an ELMy H-mode edge. The high confinement enhancement factor of ∼3.0 (HH∼1.7) was sustained, and the profiles of current and pressure approached the stationary condition after the current relaxation time. The large bootstrap current and the off-axis beam driven current sustained this reversed shear q- profile. This duration was limited only by the duration of the neutral beam injection.(author)