Electrostatic solitary waves in ion beam neutralization

TL;DR

This paper investigates the formation and effects of electrostatic solitary waves during ion beam neutralization, revealing their impact on beam neutralization efficiency and electron heating through particle-in-cell simulations.

Contribution

It presents the first detailed simulation study of ESWs in ion beam neutralization, highlighting their size, stability, and influence on neutralization performance.

Findings

ESWs reach several centimeters in size and are stable over time.

Large-amplitude ESWs reduce ion beam neutralization.

Dissipation of ESWs heats electrons and causes their escape.

Abstract

The excitation and propagation of electrostatic solitary waves(ESWs) are observed in two-dimensional particle-in-cell simulations of ion beam neutralization by electron injection by a filament. Electrons from the filament are attracted by positive ions and bounce inside ion beam pulse. Bouncing back and forth electron streams then starts to mix, creating the two-stream instability. The instability saturates with the formation of ESWs. These ESWs reach several centimeters in longitudinal size and are stable for a long time. The excitation of large-amplitude ESWs reduces the degree of neutralization of the ion beam pulse. In addition, the dissipation of ESWs causes heating of neutralizing electrons and their escape from the ion beam, leading to further reduction of neutralization degree.