Fully coherent hard X-ray generation by two-stage of Phase-merging Enhanced Harmonic Generation

TL;DR

This paper proposes a novel two-stage phase-merging enhanced harmonic generation scheme for free electron lasers, enabling fully coherent, high-brightness hard X-ray production with peak powers over 2 GW at 1 angstrom wavelength.

Contribution

It introduces a new cascading PEHG scheme with a dogleg and two PEHG stages, advancing the design for future coherent X-ray FELs.

Findings

Feasibility within current technology

Produces narrow bandwidth, fully coherent X-ray pulses

Achieves over 2 GW peak power at 1 Å wavelength

Abstract

Cascading stages of seeded free electron laser (FEL) is a promising way to produce fully coherent X-ray radiations. We study a new approach to produce coherent hard X-rays by cascading the recently proposed phase-merging enhanced harmonic generation (PEHG). The scheme consists of one dogleg and two PEHG configurations, which may be one of the leading candidates for the extracted undulator branch in future X-ray FEL facilities. FEL physics studies show that such a scheme is feasible within the present technology and can provide high brightness X-ray radiation pulses with narrow bandwidth and fully coherence, and the radiated peak power at 1 angstrom wavelength converted from an initial 200 nm seed laser is over 2 GW.