Neutralization of ion beam by electron injection, Part 2: Excitation and propagation of electrostatic solitary waves

TL;DR

This paper investigates how electrostatic solitary waves are generated and behave during the charge neutralization of an ion beam by electron injection, revealing their long-lasting nature and interactions through particle-in-cell simulations.

Contribution

It demonstrates the robust generation, long propagation, and interaction dynamics of electrostatic solitary waves during ion beam neutralization using detailed simulations.

Findings

Electrostatic solitary waves can last over 30 microseconds.

ESWs can pass through each other with minimal amplitude change.

Interactions include partial electron exchange and coalescence.

Abstract

The charge neutralization of an ion beam by electron injection is investigated using a two-dimensional electrostatic particle-in-cell code. The simulation results show that electrostatic solitary waves (ESWs) can be robustly generated in the neutralization process and last for long time (for more than 30 us); and therefore ESW can strongly affect the neutralization process. The ESWs propagate along the axis of the ion beam and reflect from the beam boundaries. The simulations clearly show that two ESWs can pass through each other with only small changes in amplitude. Partial exchange of trapped electrons in collisions of two ESWs is observed in the simulations and can explain interaction during collisions of two ESWs. Coalescence of two ESWs is also observed.