Method for the determination of the three-dimensional structure of ultrashort relativistic electron bunches

TL;DR

This paper introduces a new technique combining existing diagnostics to enable real-time, single-shot 3D imaging of ultrashort relativistic electron bunches in X-ray Free-Electron Lasers using coherent Optical Transition Radiation.

Contribution

It proposes a novel method that integrates Optical Replica Synthesizer and Optical Transition Radiation imaging for 3D electron bunch characterization.

Findings

Demonstrates feasibility of 3D imaging of ultrashort electron bunches

Enables real-time, single-shot measurements

Utilizes coherent radiation for high-resolution imaging

Abstract

We describe a novel technique to characterize ultrashort electron bunches in X-ray Free-Electron Lasers. Namely, we propose to use coherent Optical Transition Radiation to measure three-dimensional (3D) electron density distributions. Our method relies on the combination of two known diagnostics setups, an Optical Replica Synthesizer (ORS) and an Optical Transition Radiation (OTR) imager. Electron bunches are modulated at optical wavelengths in the ORS setup. When these electron bunches pass through a metal foil target, coherent radiation pulses of tens MW power are generated. It is thereafter possible to exploit advantages of coherent imaging techniques, such as direct imaging, diffractive imaging, Fourier holography and their combinations. The proposed method opens up the possibility of real-time, wavelength-limited, single-shot 3D imaging of an ultrashort electron bunch.