Fluctuations in Plasma Equilibrium Control on JT-60U

Experimental analyses are presented of fluctuations observed in a plasma-current-center, I_p-center, location and the inward clearance between the outermost flux surface and the first wall at plasma perturbations (e.g., β_p collapse and disruption) for JT-60U divertor plasmas. The neutral point for vertical and horizontal movement of the I_p center at plasma disturbances is confirmed, and attachment of the plasma to the inward first wall is avoided because of the increase in l_i, at fast plasma-current quench. These experimental observations will support the design of fusion reactors like the International Thermonuclear Experimental Reactor (ITER).