Analytical and numerical studies of the complex interaction of a fast ion beam pulse with a background plasma

Abstract

Summary form only given. Plasma neutralization of an intense ion beam pulse is of interest for many applications, including plasma lenses, heavy ion fusion, high energy physics, etc. Comprehensive analytical, numerical and experimental studies are underway to investigate the complex interaction of a fast ion beam with a background plasma. The positively charged ion beam attracts plasma electrons, and as a result, the plasma electrons have a tendency to neutralize the beam charge and current. An analytical electron fluid model has been developed to describe the plasma response to a propagating non-relativistic ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration is much longer than the electron plasma period. In the opposite limit, the beam pulse excites large-amplitude plasma waves. If the beam density is larger than plasma background density, the plasma waves break. Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. A suite of particle-in-cell codes has been developed to study the propagation of an ion beam pulse through the background plasma. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The reduced fluid description derived in this paper can provide an important benchmark for numerical codes and yield scaling relations for different beam and plasma parameters. The visualization of the data obtained in the numerical simulations shows complex collective phenomena during beam entry into and exit from the plasma.