Hydrodynamic response of converter target impacted by high-current relativistic electron beam

Abstract

The typical response of the X-ray converter material impacted by an intense relativistic electron beam is vaporization and rapid expansion. For the Dragon-I accelerator (2.5 kA, 20 MeV, 60 ns), the slab target is replaced by a multi-foil target in order to reduce the unwanted debris ejected from the target. Comparisons of the output X-ray performance and the hydrodynamic response between the slab target and the multi-foil target are calculated by numerical methods. We found that vaporization and melt ejection dominate the hydrodynamic response in the multi-foil target while the mechanical effect plays an important role in the slab target. We also report the single-pulse experiments which measure the surface density decrease of the converter material after a specified delay. The experimental results show good agreement with the numerical prediction. Hydrodynamic response of the multi-foil target impacted by three successive pulses in 1 μs is also studied by simulation. The results indicate that although the surface density of the material decreases rapidly during the inter-pulse time scale, the X-ray dose produced by the second and the third pulse will nearly maintain the same as the first one.