Acceleration rate enhancement by negative plasma density gradient in multi-bunch driven plasma wakefield accelerator

TL;DR

This paper explores how a small negative plasma density gradient can locally enhance the acceleration rate in multi-bunch driven plasma wakefield accelerators, improving energy gain within limited plasma lengths.

Contribution

It introduces a regime where a negative plasma density gradient stabilizes the wave phase and boosts energy transfer efficiency in plasma wakefield acceleration.

Findings

Negative density gradient increases acceleration rate.

Wave phase stability is maintained with the gradient.

Enhanced energy gain in limited plasma sections.

Abstract

In a plasma wakefield accelerator driven by a train of short particle bunches, it is possible to locally increase the acceleration rate by introducing a small negative gradient of the plasma density. A regime is possible in which the gradient affects only the relative phasing of the driver bunches and the wave, keeping the wave phase behind the driver stable. With this technique, it is possible to increase the energy gain of the accelerated witness bunch in a plasma section of limited length.