Together with one of its variants, the recently proposed phase-merging enhanced harmonic generation (PEHG) free-electron lasers (FELs) have been systematically studied in this paper. Different form the standard-HGHG, a transverse gradient undulator is employed for introducing a phase-merging effect into the transversely dispersed electron beam in PEHG. The analytical theory of the phase-merging effect and the physical mechanism behind the phenomenon were presented. Using a representative and realistic set of beam parameters, intensive start-to-end simulations for soft x-ray FEL generation were given to illustrate the performance of PEHG. Moreover, some practical issues that may affect the performance of PEHG were also discussed.
@article{arxiv.1312.2823,
title = {Phase-merging Enhanced Harmonic Generation Free-electron Laser},
author = {Chao Feng and Haixiao Deng and Dong Wang and Zhentang Zhao},
journal= {arXiv preprint arXiv:1312.2823},
year = {2015}
}