Numerical investigation on relativistic electron scattering by a plasma density gradient

Abstract

A Monte-Carlo code based on a single scattering model is developed for numerical investigations on relativistic electron scattering by a plasma density gradient in electron radiography. A relativistic electron beam is taken to side-on radiograph a steep density gradient region in a fully ionized polystyrene foil target and the beam’s kinetic energy is chosen to be much higher than its energy loss in the target. The beam profile of the transmitted electrons on the radiograph shows a modulation of peak-to-trough structure due to electron scattering from the density gradient region. For a 30 μm thick target made up of densities from 1 g cm−3 to 3 g cm−3 across the gradient region, a maximum modulation contrast of about 13% could be produced. The influence of beam energy and spread, density gradient width, detection distance, and plasma self-generated electromagnetic fields are investigated. In an approximation of multiple scattering, an analytical model is introduced to assist in the interpretation of the scattering characteristics resulting from the density gradient. The modulation features and their relations to the gradient width may be applied to diagnose a steep density gradient region of width 1 μm in dense plasma.