Investigation of pressure profile controllability during plasma current ramp-up with reduced magnetic flux consumption in JT-60SA

Wakatsuki, Takuma; Suzuki, Takahiro; Hayashi, Nobuhiko; Shiraishi, Junya; Ide, Shunsuke; Kubo, Hirotaka; Takase, Yuichi*

Feasibility of plasma current ramp-up in JT-60SA without additional CS flux consumption after initial plasma formation has been investigated using an integrated modeling code suite (TOPICS). In our previous study, we developed a scenario in which the plasma current is ramped-up from 0.6 MA to 2.1 MA without additional CS flux consumption by overdriving the plasma current using neutral beams (NB) and electron cyclotron (EC) waves. The investigation of the ramp-up scenarios with several prescribed density profiles revealed that a pressure profile with an H-mode pedestal and a wide internal transport barrier (ITB) whose foot is located at a large minor radius is required in order to obtain a large bootstrap current within the MHD stability limit. In this study, we introduce a particle transport model according to experimental results of JT-60U. Particle transport is calculated by assuming that the particle diffusivity is a sum of neoclassical and anomalous diffusivities and particle pinch velocity is zero. As a result, it is shown that the location and strength of the ITB can be modified by changing the heating, current drive and fueling method using NB and EC. An ITB which is strong enough to overdrive the plasma current can be obtained within the proposed NB and EC capability at JT-60SA. We will show controllability of the pressure profile considering the ideal MHD stability.