Effect of plasma elongation on current dynamics during tokamak\n disruptions

Abstract

Plasma terminating disruptions in tokamaks may result in relativistic runaway\nelectron beams with potentially serious consequences for future devices with\nlarge plasma currents. In this paper we investigate the effect of plasma\nelongation on the coupled dynamics of runaway generation and resistive\ndiffusion of the electric field. We find that elongated plasmas are less likely\nto produce large runaway currents, partly due to the lower induced electric\nfields associated with larger plasmas, and partly due to direct shaping\neffects, which mainly lead to a reduction in the runaway avalanche gain.\n