Longitudinally resolved measurement of energy-transfer efficiency in a plasma-wakefield accelerator

TL;DR

This paper introduces a noninvasive, longitudinally resolved diagnostic technique for measuring local energy-transfer efficiency in plasma-wakefield accelerators, achieving up to 58% efficiency, which aids optimization and stability studies.

Contribution

The paper presents a novel optical diagnostic method for noninvasively measuring local energy-transfer efficiency in plasma accelerators, enabling real-time optimization and detailed stability analysis.

Findings

Achieved up to 58% local energy-transfer efficiency measurement.

Demonstrated noninvasive, longitudinally resolved diagnostic capability.

Enabled studies of efficiency relation to transverse instability.

Abstract

Energy-transfer efficiency is an important quantity in plasma-wakefield acceleration, especially for applications that demand high average power. Conventionally, the efficiency is measured using an electron spectrometer; an invasive method that provides an energy-transfer efficiency averaged over the full length of the plasma accelerator. Here, we experimentally demonstrate a novel diagnostic utilizing the excess light emitted by the plasma after a beam-plasma interaction, which yields noninvasive, longitudinally resolved measurements of the local energy-transfer efficiency from the wake to the accelerated bunch; here, as high as (58 $\pm$ 3)%. This method is suitable for online optimization of individual stages in a future multistage plasma accelerator, and enables experimental studies of the relation between efficiency and transverse instability in the acceleration process.