Rotational Stabilization of Resistive Wall Mode on JT-60U

抄録

We have carried out experiments to clarify the stabilizing effect of a plasma rotation on the resistive wall mode (RWM) that could limit the achievable-β_N in high-β_N plasmas above the no-wall ideal β_N-limit. On JT-60U plasma rotations are controlled using neutral beams with varying combinations of net torque input while keeping β_N constant. The RWM is destabilized as the plasma rotation is being reduced. Detailed measurements of the mode structure revealed that the RWM has a global structure that rotates with the order of the resistive wall time. In these experiments, it is found that the critical toroidal rotation speed for the RWM stabilization is less than 1% of the Alfvén speed. Moreover, the critical rotation does not strongly depend on β_N. The results suggest that high-β_N operation up to the ideal wall β_N-limit could be possible by suppressing the RWM with a slow plasma rotation in fusion reactors.