THz based phase space manipulation in a zero-slippage IFEL

TL;DR

This paper proposes a THz-driven phase space manipulation technique in a zero-slippage IFEL to compress relativistic electron bunches and synchronize them with lasers, using a guided broadband THz source and waveguide for sustained interaction.

Contribution

It introduces a novel THz-based phase space manipulation method in an IFEL with group velocity matching, enabling efficient electron bunch compression and synchronization.

Findings

Demonstrated waveform measurement before and after waveguide

Predicted nearly tenfold electron bunch compression

Potential for femtosecond-scale temporal resolution in diagnostics

Abstract

We describe an IFEL interaction driven by a guided broadband THz source to compress a relativistic electron bunch and synchronize it with an external laser pulse. A high field near single-cycle THz pulse, generated via optical rectification from the external laser source, is group velocity-matched to the electron bunch inside a waveguide, allowing for a sustained interaction in a magnetic undulator. We present measurements of the THz waveform before and after a curved parallel plate waveguide with varying aperture size and estimate the reduced group velocity. For a proof-of-concept experiment at the UCLA PEGASUS laboratory, a 6 MeV, 100 fs electron bunch with an initial 0.03 % energy spread can be readily produced. Given these parameters and a projected THz peak field of 10 MV/m, our simulation model predicts a phase space rotation of the bunch distribution that compresses the electron bunch by nearly an order of magnitude and reduces any initial timing jitter within the phase acceptance window. We also discuss the application of this guided-THz IFEL experimental set-up towards a THz streaking diagnostic with the potential for femtosecond scale temporal resolution.