Cascaded high-gradient terahertz-driven acceleration of relativistic electron beams

TL;DR

This paper demonstrates a significant advancement in terahertz-driven electron acceleration, achieving record energy gains and cascaded acceleration with high gradients, paving the way for compact, efficient electron sources.

Contribution

It reports the first cascaded relativistic electron acceleration using THz fields, achieving a 204 keV energy gain in a two-stage setup with high acceleration gradients.

Findings

Record single-stage energy gain of 170 keV.

First demonstration of cascaded THz-driven acceleration.

Achieved average gradient of 85 MV/m with peak field of 1.1 GV/m.

Abstract

Terahertz (THz)-driven acceleration has recently emerged as a new route for delivering ultrashort bright electron beams efficiently, reliably, and in a compact setup. Many THz-driven acceleration related working schemes and key technologies have been successfully demonstrated and are continuously being improved to new limits. However, the achieved acceleration gradient and energy gain remain low, and the potential physics and technical challenges in the high field and high energy regime are still under-explored. Here we report a record energy gain of 170 keV in a single-stage configuration, and demonstrate the first cascaded acceleration of a relativistic beam with a 204 keV energy gain in a two-stages setup. Whole-bunch acceleration is accomplished with an average accelerating gradient of 85 MV/m and a peak THz electric field of 1.1 GV/m. This proof-of-principle result is a crucial advance in THz-driven acceleration with a major impact on future electron sources and related scientific discoveries.