Experimental study of the runaway beam in the J-TEXR Tokamak

Plasma major disruption on the Tokamak often generated runaway beam which contains electrons with energies of several tens megaelectronvolts. It can cause substantial damage when it loss the control and hits the limiters or the vessel wall. Soft X-ray line emission result from the interaction between the runaway electrons and the impurities inside the plasma could provide runaway generation process and the confinement of runaway electrons. The vertical soft X-ray array at the top of the J-TEXT was used to study the disruption generated runaway beam. The runaway production and the confinement of runaway beam were obtained from the soft X-ray line emission. (authors)