A numerical study on plasma acceleration processes with ion dynamics at the sub-nanosecond timescale

TL;DR

This study uses numerical simulations to investigate how ion dynamics influence plasma recovery times in wakefield acceleration, comparing Particle-in-Cell and fluid models to understand their effectiveness.

Contribution

It provides new insights into ion motion effects on plasma recovery and evaluates the accuracy of fluid models against Particle-in-Cell simulations.

Findings

Ion dynamics significantly affect plasma recovery times.

Fluid models can approximate Particle-in-Cell results under certain conditions.

Non-monotonic plasma recovery dependence on initial density is explained by ion motion.

Abstract

Plasma wakefield acceleration is a groundbreaking technique for accelerating particles, capable of sustaining gigavolt-per-meter accelerating fields. Understanding the physical mechanisms governing the recovery of plasma accelerating properties over time is essential for successfully achieving high-repetition-rate plasma acceleration, a key requirement for applicability in both research and commercial settings. In this paper, we present numerical simulations of the early-stage plasma evolution based on the parameters of the SPARC_LAB hydrogen plasma recovery time experiment (Pompili et al., Comm. Phys. 7, 241 (2024)), employing spatially resolved Particle-in-Cell and fluid models. The experiment reports on a non-monotonic dependence of the plasma recovery time on the initial plasma density, an effect for which ion motion has been invoked as a contributing factor. The simulations presented here provide further insight into the role of ion dynamics in shaping this behavior. Furthermore, comparing Particle-in-Cell and fluid approaches allows us to assess the quality of fluid models for describing this class of plasma dynamics.