Nonlinear plasma waves driven by short ultrarelativistic electron bunches

TL;DR

This paper develops a theory and simulation approach to study nonlinear plasma wave excitation by ultrarelativistic electron bunches, revealing bubble formation dynamics and secondary wave effects.

Contribution

It introduces a quasistatic approximation and a novel electrostatic-like particle-in-cell code to analyze plasma bubbles driven by ultrarelativistic electrons, including simple models for large charge regimes.

Findings

Determined plasma bubble radius and length for different beam charges.

Identified secondary plasma waves caused by expelled electrons.

Explained bubble formation mechanisms at high charges.

Abstract

We advance a theory of quasistatic approximation and investigate the excitation of nonlinear plasma waves by the driving beam of ultrarelativistic electrons using novel electrostatic-like particle- in-cell code. Assuming that the beam occupies an infinitesimally small volume, we find the radius and length of the plasma bubble formed in the wake of the driver for varying values of the beam charge. The mechanism of the bubble formation is explained by developing simple models of the bubble at large charges. Plasma electrons expelled by the driver charge excite secondary plasma waves which complicate the plasma electron flow near the bubble boundary.