Proposal for High-harmonic EEHG Lasing at Shanghai Deep Ultra-Violet Free-electron Laser

TL;DR

This paper explores the feasibility of achieving high-harmonic EEHG lasing at the 10th harmonic at SDUV-FEL through physical design and simulations, demonstrating potential approaches with minimal impact from coherent synchrotron radiation.

Contribution

It presents the first detailed investigation and simulation of 10th harmonic EEHG lasing at SDUV-FEL using two different seed laser configurations.

Findings

Both seed laser configurations could enable 10th harmonic EEHG lasing.

Coherent synchrotron radiation has minimal effect on EEHG performance.

Simulations show promising results for high-harmonic EEHG at SDUV-FEL.

Abstract

The echo-enabled harmonic generation (EEHG) free-electron laser (FEL) has been already demonstrated at lower harmonics and the first lasing at third harmonic also has been achieved at Shanghai deep ultra-violet FEL (SDUV-FEL). While the great advantage of much higher harmonic up-conversion efficiency of EEHG over other seeded FELs only shows evidently at much higher harmonics. In this paper, we investigate the possibility of EEHG lasing at 10-th harmonic of the seed laser at SDUV-FEL, both physical designs and numerical simulations have been studied carefully. Two proposals of EEHG at 10-th harmonic have been studied respectively, i.e. with the seed lasers of the same color and two difference colors, the simulation results indicate that both approaches could be the candidate for EEHG lasing at 10-th harmonic at SDUV-FEL, meanwhile the coherent synchrotron radiation does not affect the performance of EEHG-FEL but only slightly shifts the central radiation frequency.