1D3V PIC simulation of propagation of relativistic electron beam in an inhomogeneous plasma

TL;DR

This study uses 1D3V PIC simulations to demonstrate that plasma inhomogeneity suppresses filamentation instability, enhancing relativistic electron beam transport in inhomogeneous plasmas, with detailed analysis of various parameters affecting this suppression.

Contribution

First detailed PIC simulation analysis showing how plasma inhomogeneity suppresses filamentation instability for relativistic electron beams.

Findings

Inhomogeneous plasma suppresses filamentation instability.

Beam propagation is improved in inhomogeneous plasma regimes.

Inhomogeneity scale length and amplitude significantly influence instability suppression.

Abstract

A recent experimental observation has shown efficient transport of Mega Ampere of electron currents through aligned carbon nanotube arrays [Phys. Rev Letts. 108, 235005 (2012)]. The result was subsequently interpreted on the basis of suppression of the filamentation instability in an inhomogeneous plasma [Phys. Plasmas 21, 012108 (2014)]. This inhomogeneity forms as a result of the ionization of the carbon nanotubes. In the present work a full 1D3V Particle-in-Cell (PIC) simulations have been carried out for the propagation of relativistic electron beams (REB) through an inhomogeneous background plasma. The suppression of the filamentation instability, responsible for beam divergence, is shown. The simulation also confirms that in the nonlinear regime too the REB propagation is better when it propagates through a plasma whose density is inhomogeneous transverse to the beam. The role of inhomogeneity scale length, its amplitude and the transverse beam temperature etc., in the suppression of the instability is studied in detail.