Effect of plasma inhomogeneity on plasma wakefield acceleration driven by long bunches

TL;DR

This study numerically investigates how plasma inhomogeneity affects wakefield acceleration driven by long proton bunches, highlighting the importance of density uniformity for efficient particle acceleration.

Contribution

It provides new insights into the impact of plasma density variations on wakefield phase stability and particle acceleration efficiency in long-bunch driven plasma accelerators.

Findings

Plasma inhomogeneity causes phase shifts and particle loss.

Wakefield wavelength changes are sensitive to density variations.

Transverse instability is less affected by inhomogeneity.

Abstract

Effects of plasma inhomogeneity on self-modulating proton bunches and accelerated electrons were studied numerically. The main effect is the change of the wakefield wavelength which results in phase shifts and loss of accelerated particles. This effect imposes severe constraints on density uniformity in plasma wakefield accelerators driven by long particle bunches. The transverse two stream instability that transforms the long bunch into a train of micro-bunches is less sensitive to density inhomogeneity than are the accelerated particles. The bunch freely passes through increased density regions and interacts with reduced density regions.