Potential For Laser-Induced Microbunching Studies with the 3-MHZ-Rate Electron Beams at ASTA

TL;DR

This paper proposes experiments at ASTA to study laser-induced microbunching in electron beams, aiming to improve diagnostics and free-electron laser performance using high-repetition-rate micropulses.

Contribution

It introduces a novel experimental setup at ASTA to investigate microbunching effects with high repetition rate electron beams, combining diagnostics and free-electron laser applications.

Findings

Potential to generate coherent optical/UV radiation via microbunching

Measurement of microbunching factors related to HGHG

Use of 3-MHz micropulse train for detailed studies

Abstract

Investigations of the laser-induced microbunching as it is related to time-sliced electron-beam diagnostics and high-gain-harmonic generation (HGHG) free-electron lasers using bright electron beams are proposed for the ASTA facility. Initial tests at 40-50 MeV with an amplified 800-nm seed laser beam co-propagating with the electron beam through a short undulator (or modulator) tuned for the resonance condition followed by transport through a subsequent chicane will result in energy modulation and z-density modulation (microbunching), respectively. The latter microbunching will result in generation of coherent optical or UV transition radiation (COTR, CUVTR) at a metal converter screen which can reveal slice beam size, centroid, and energy spread. Additionally, direct assessment of the microbunching factors related to HGHG by measurement of the COTR intensity and harmonic content after the chicane as a function of seed laser power and beam parameters will be done. These experiments will be performed using the ASTA 3-MHz-rate micropulse train for up to 1ms which is unique to test facilities in the USA.