Differential pumping for kHz operation of a Laser Wakefield accelerator based on a continuously flowing Hydrogen gas jet

TL;DR

This paper demonstrates a novel differential pumping system enabling continuous kHz Laser Wakefield Acceleration with a high-pressure Hydrogen gas jet, maintaining low pressure and improving beam quality for practical applications.

Contribution

The work introduces a new differential pumping design that allows continuous Hydrogen gas flow in kHz LWFA experiments, a significant advancement over previous pulsed or limited-flow setups.

Findings

Achieved continuous kHz LWFA operation with Hydrogen gas jet

Maintained pressure below 3e-4 mbar at 140 bar backing pressure

Validated system design with fluid dynamics and optical simulations

Abstract

Laser-Wakefield Accelerators (LWFA) running at kHz repetition rates hold great potential for applications. They typically operate with low-energy, highly compressed laser pulses focused in high-pressure gas targets. Experiments have shown that the best-quality electron beams are achieved using Hydrogen gas targets. However, continuous operation with Hydrogen requires a dedicated pumping system. In this work, we present a method for designing a differential pumping system, which we successfully implemented in our experiments. This enabled the first demonstration of continuous operation of a kHz LWFA using a high-pressure Hydrogen gas jet. The system effectively maintained a pressure below 3e-4 mbar, even with a free-flowing gas jet operating at 140 bar backing pressure. Numerical fluid dynamics and optical simulations were used to guide and validate the system's design.