Numerical simulations of electron acceleration driven by heavy ion beams in plasma with alternating density gradients

TL;DR

This paper proposes a novel plasma density modulation technique to enhance electron acceleration efficiency driven by heavy ion beams, overcoming limitations of short dephasing length and wakefield degradation.

Contribution

It introduces a method of periodically switching the witness beam phase to maintain wakefield structure and improve energy gain in plasma acceleration with heavy ion drivers.

Findings

The proposed phase switching method maintains wakefield stability.

Simulation results show increased energy gain of the witness beam.

The technique mitigates wakefield degradation caused by plasma density mismatches.

Abstract

Plasma-Based Acceleration (PBA) has been demonstrated using laser, electron, and proton drivers. However, significant challenges remain in achieving high efficiency, stable acceleration, and scalable energy gain. Heavy ion beam drivers, with their high kinetic energy, offer the potential for greater energy transfer to the witness beam. Unfortunately, limited by the relatively low velocity of heavy ion, the dephasing length is really short leading to a low energy gain of the witness beam. Conventional method that increase plasma density linearly is ineffective in this context because the mismatch between the RMS beam radius and plasma wavelength will make the wakefield degrade or even disappear. In this paper, we propose a method that periodically switches the witness beam between different accelerating phase, allowing it to shift between adjacent accelerating cavities. Therefore, the plasma density does not only strictly increase, but also decrease. This will help maintain the structure of wakefield and increase the energy gain of the witness beam.