Real-time measurement and feedback control of ion temperature profile and toroidal rotation using fast CXRS system in JT-60U

A fast charge exchange recombination spectroscopy (CXRS) system has been developed for the real-time measurement and feedback control of ion temperature (T_i) profile and toroidal rotation velocity (V_t) in JT-60U. In order to control T_i and V_t in real-time, the charge exchange recombination spectroscopy with high time resolution, the real-time processor system, and the real-time control system have been developed. Utilizing this system, real-time control of the T_i gradient between r/a ∼ 0.25-0.5 has been demonstrated with neutral beams at high beta plasmas (normalized beta β_N ∼ 1.6-2.8). The strength of the internal transport barrier is controlled. Moreover, the real-time control of V_t has been demonstrated from counter (anti-parallel to the plasma current, I_p) to co (parallel to the I_p) direction. Then the behavior of edge localized mode (ELM) is changed by controlling the V_t.