Target-Plasma Expansion Induced by 20-MeV Intense Electron Beam

The typical response of an X-ray converter material to the passage of a high-current relativistic electron beam is ionization and rapid dispersal. Experiments have been performed on the Dragon-I linear induction accelerator to study this phenomenon. In this paper, we report the fast photography and Faraday cup experiments performed to quantify the plasma-plume expansion and velocities of ions. Monte Carlo simulation shows that the energy deposition in a multilayer target is about 7 kJ/g. By solving the Saha equation, the ionization degree of the plasma was figured out to be only 14%.