An Electron Beam Penetrating an Overdense Plasma Simulated with Fine Resolution on a Long Timescale

Summary form only given. When an electron beam encounters an overdense plasma, the beam is quickly destabilized by the two stream instability and dispersed. However, it was shown previously by means of 2D simulations that over long time scales the beam ejects the background electrons from the region where the beam is propagating, leaving the background ions to neutralize the beam charge, thus stabilizing the beam propagation over timescales that are long compared to the electron-electron two stream instability growth time. Subsequently, long timescale simulations with coarse spatial resolution were presented which seemed to show that the behavior carried over to 3D, although a firm conclusion was not possible because of the coarse resolution. The purpose of this paper is to present simulations of the interaction between the beam and the overdense plasma in 3D with a spatial resolution comparable to the resolution of the 2D calculations. It is shown that some 3D modes grow to a moderate amplitude, but that these do not cause disruption of the plasma on the simulated timescale. These simulations thus show that the stable beam propagation at longer times that was found in the 2D simulations is also found when 3 dimensional perturbations are included