Short Electron Bunch Generation Using Single-Cycle Ultrafast Electron Guns

TL;DR

This paper presents a novel approach to generate ultrashort, high-charge electron bunches using single-cycle THz pulses in compact guns, enabling high acceleration gradients and ultrahigh brightness for advanced applications.

Contribution

It demonstrates that low-energy THz pulses can produce relativistic electron bunches in a compact setup, advancing miniaturized ultrafast electron source technology.

Findings

THz pulses as low as 20 ?J can generate multi-10 keV electron bunches.

2 mJ THz energy can produce electron bunches exceeding 2 MeV.

Achieved electron bunch durations of 30 fs at 30 keV and 45 fs at 2 MeV.

Abstract

We introduce a solution for producing ultrashort ($\sim$fs) high charge ($\sim$pC) from ultra-compact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20 ?J are sufficient to generate multi-10 keV electron bunches. Moreover, It is demonstrated that THz energies of 2mJ are sufficient to generate relativistic electron bunches with higher than 2 MeV energy. The high acceleration gradients possible in the structures provide 30 fs electron bunches at 30 keV energy and 45 fs bunches at 2 MeV energy. These structures will underpin future devices for strong field THz physics in general and miniaturized electron guns, in which the high fields combined with the short pulse duration enable electron beams with ultrahigh brightness.