Towards a compact all optical terahertz-driven electron source at Tsinghua University

TL;DR

This paper presents a compact, all-optical terahertz-driven electron source design with optimized components, capable of producing high-quality electron beams suitable for tabletop applications, and demonstrates promising simulation results.

Contribution

It introduces a novel design of a compact THz-driven electron source integrating multiple components, with detailed simulations showing high beam quality and stability under realistic conditions.

Findings

Produces 19 fC, 3 MeV electron beams with low emittance

Achieves a minimum energy spread of 0.04% and bunch length of 6.1 fs

Demonstrates effective operation under 1.5% THz power jitter

Abstract

We propose a physical design of a compact all optical terahertz (THz)-driven electron source. The 300 mm accelerator beamline, powered by Joule level laser system, is easily to be integrated to tabletop scale. A dual-feed THz-driven electron gun with an exponential impedance, a tapered dielectric loaded cylindrical waveguide, THz-driven bunch compressors and permanent magnet solenoids (PMS) have been designed and optimized. Dynamics simulations show that the electron source can deliver a 19 fC, 3 MeV electron beams with a normalized transverse emittance of 0.079 {\pi}.mm.mrad. A minimum relative energy spread of 0.04% or a minimum root-mean-square bunch length of 6.1 fs can be achieved by adjusting the beam shaping line. Sensitivity analysis shows that the THz-driven electron source can effectively work under a 1.5% energy jitter of the THz power system. Simulated diffraction pattern up to the fourth order of an aluminum sample based on the beamline can be clearly distinguished. A prototype THz gun has beam fabricated and is now under testing, more results will be reported in future works.