Tomography analysis for resistive interchange mode driven internal disruption in Heliotron E

Sawtooth oscillations and internal disruptions are investigated in currentless heliotron plasmas with soft X-ray arrays. The time evolution of the tomographical images of the crash phase is studied and the m=2 mode is seen dominantly, where m is a poloidal mode number. The relative decrease of soft X-ray intensity is roughly proportional to the amplitude of the m=2 mode at the crash. The growth rate of the m=2 mode before the crash is show as a function of the radial gradient of background soft X-ray intensity near the q=2 rational surface, where q is a safety factor. (author)