Particle control study towards burning plasma control in JT-60U

Takenaga, Hidenobu; JT-60 Team

Particle control is important for burning plasma control, because fuel density is one of a few controllable parameters in a burning plasma. First, mechanisms responsible for determining density profiles and dependence of impurity transport on density profiles were investigated. Peakedness of density profiles increased with decreasing collisionality, which is consistent with ITG/TEM turbulence theory. However, other hidden parameters, such as toroidal rotation, existed. Metal impurity accumulation was observed with peaked density profile, while light impurity accumulation was not. Next, effects of fuelling on confinement was investigated using newly installed supersonic molecular beam injection (SMBI). SMBI directly affected the plasma parameters at r/a 0.8 as similar as pellet injection. However, confinement degraded with constant pedestal pressure in contrast to pellet injection. Using the burning plasma simulation scheme, it was demonstrated to reduce the simulated a-heating with SMBI due to confinement degradation and flattening of pressure profile.