Plasma terminating disruptions in tokamaks may result in relativistic runaway
electron beams with potentially serious consequences for future devices with
large plasma currents. In this paper we investigate the effect of plasma
elongation on the coupled dynamics of runaway generation and resistive
diffusion of the electric field. We find that elongated plasmas are less likely
to produce large runaway currents, partly due to the lower induced electric
fields associated with larger plasmas, and partly due to direct shaping
effects, which mainly lead to a reduction in the runaway avalanche gain.Comment: 11 pages, 3 figure