The ion motion in self-modulated plasma wakefield accelerators

TL;DR

This paper investigates how plasma ion motion affects self-modulated plasma wakefield accelerators, revealing that ion dynamics can limit acceleration efficiency and proposing mitigation strategies based on analytical modeling and simulations.

Contribution

It develops an analytical model for ion motion in narrow beam regimes and demonstrates its impact on self-modulation instability and acceleration gradients.

Findings

Ion motion causes early saturation of self-modulation

Ion dynamics suppresses accelerating gradients

Mitigation methods can reduce ion motion effects

Abstract

The effects of plasma ion motion in self-modulated plasma based accelerators is examined. An analytical model describing ion motion in the narrow beam limit is developed, and confirmed through multi-dimensional particle-in-cell simulations. It is shown that the ion motion can lead to the early saturation of the self-modulation instability, and to the suppression of the accelerating gradients. This can reduce the total energy that can be transformed into kinetic energy of accelerated particles. For the parameters of future proton-driven plasma accelerator experiments, the ion dynamics can have a strong impact. Possible methods to mitigate the effects of the ion motion in future experiments are demonstrated.