Few-Cycle Pulse Generation in an X-Ray Free-Electron Laser

TL;DR

This paper proposes a novel method to generate extremely short, few-cycle x-ray pulses using an FEL with an afterburner extension, achieving pulse durations around 700 zeptoseconds, vastly shorter than traditional FELs.

Contribution

The paper introduces a compact afterburner extension for FELs that produces ultrashort x-ray pulses with unprecedented brevity and spectral properties, advancing FEL technology.

Findings

Pulse durations of approximately 700 zeptoseconds achieved.

Spectrum is discretely multichromatic with increased bandwidth.

Method significantly shortens pulse duration compared to standard FELs.

Abstract

A method is proposed to generate trains of few-cycle x-ray pulses from a Free-Electron Laser (FEL) amplifier via a compact 'afterburner' extension consisting of several few-period undulator sections separated by electron chicane delays. Simulations show that in the hard x-ray (wavelength ~0.1 nm; photon energy ~10 keV) and with peak powers approaching normal FEL saturation (GW) levels, root mean square pulse durations of 700 zeptoseconds may be obtained. This is approximately two orders of magnitude shorter than that possible for normal FEL amplifier operation. The spectrum is discretely multichromatic with a bandwidth envelope increased by approximately two orders of magnitude over un-seeded FEL amplifier operation. Such a source would significantly enhance research opportunity in atomic dynamics, and push capability towards nuclear dynamics.