Development of Reversed Shear Plasmas with Large Bootstrap Current Fraction towards Reactor Relevant Regime in JT-60U

Abstract. This paper reports the development of reversed magnetic shear (RS) plasmas with a large bootstrap current fraction (fBS) towards reactor relevant regime, especially lower q95 regime. By utilizing large volume configuration close to the conductive wall for wall stabilization, the beta limit of RS plasmas is significantly improved. As a result, high confinement RS plasmas with large fBS exceeding no-wall beta limit are obtained in reactor relevant regime, where βN~2.7, βp~2.3 is achieved with reversed q profile with qmin~2.4, and then HH98y2~1.7, ne/nGW~0.87 and fBS~90% are also obtained at q95~5.27.