Particle-in-cell simulations of an RF emission mechanism associated with hypervelocity impact plasmas

Abstract

Radio frequency (RF) emission from hypervelocity impacts has been detected in multiple experiments, but the physical mechanism responsible is not well understood. Plasma is created by these impacts and rapidly expands into the surrounding vacuum; it's been argued that the observed RF emission is associated with a process in the plasma. A recent model proposes that coherent oscillations from a large scale charge separation due to the expansion of the plasma can produce RF. In this paper, we use a discontinuous Galerkin particle-in-cell technique to simulate this process. Initial conditions are drawn from hydrocode impact simulations, and the results are compared to experimental measurements. Under the assumption that there exists a difference in bulk speed of electrons and ions at a certain point in the expansion, we do find that radiation is produced by the plasma.