Controlling external injection in laser-plasma accelerators with terahertz frequency bunch manipulation

TL;DR

This paper introduces a terahertz-controlled electron bunch injection method for laser-plasma accelerators, enabling stable, high-quality, GeV-scale acceleration with minimal energy jitter and spread.

Contribution

It presents a novel terahertz-frequency approach for external electron injection that improves beam stability and quality in laser-plasma accelerators.

Findings

Numerical simulations show GeV-scale acceleration with 0.2% energy jitter.

Terahertz control enables sub-10-fs electron bunch compression.

The method improves stability for multi-stage laser-driven accelerators.

Abstract

Laser-plasma wakefield acceleration (LWFA) offers ultrahigh accelerating gradients in compact setups, but the complex non-linear nature of the process makes it challenging to generate high-quality beams. Injection of electron bunches from an external source into a plasma accelerator provides a promising route to improved performance; however, electron bunches from conventional radio-frequency (RF)-based injectors suffer from non-linear compression and laser-beam asynchrony, leading to energy jitter and emittance growth. We present a fundamental concept of terahertz-controlled electron bunches for external injection into LWFA. This terahertz-frequency approach provides temporal locking between the electron beam and the drive laser, and enables the compression of high-quality beams to sub-10-fs durations before injection into the LWFA. Numerical simulations demonstrate that GeV-scale acceleration with excellent beam quality and stability -- energy jitter and energy spread around 0.2% -- can be achieved using this method. This concept opens new opportunities for stable, multi-stage laser-driven accelerators and supports the development of next-generation applications such as free-electron lasers (FELs).