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arXiv · 1501.00130

Beam energy distribution influences on density modulation efficiency in seeded free-electron lasers

Guanglei Wang·Chao Feng·Haixiao Deng·Weiqing Zhang·Guorong Wu·Dongxu Dai·Dong Wang·Zhentang Zhao·Xueming Yang
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Abstract

The beam energy spread at the entrance of undulator system is of paramount importance for efficient density modulation in high-gain seeded free-electron lasers (FELs). In this paper, the dependences of high harmonic micro-bunching in the high-gain harmonic generation (HGHG), echo-enabled harmonic generation (EEHG) and phase-merging enhanced harmonic generation (PEHG) schemes on the electron energy spread distribution are studied. Theoretical investigations and multi-dimensional numerical simulations are applied to the cases of uniform and saddle beam energy distributions and compared to a traditional Gaussian distribution. It shows that the uniform and saddle electron energy distributions significantly enhance the performance of HGHG-FELs, while they almost have no influence on EEHG and PEHG schemes. A numerical example demonstrates that, with about 84keV RMS uniform and/or saddle slice energy spread, the 30th harmonic radiation can be directly generated by a single-stage seeding scheme for a soft x-ray FEL facility.

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Guanglei Wang, Chao Feng, Haixiao Deng, Weiqing Zhang, Guorong Wu, Dongxu Dai, Dong Wang, Zhentang Zhao, Xueming Yang. 2014-12-31. Beam energy distribution influences on density modulation efficiency in seeded free-electron lasers. https://arxiv.org/abs/1501.00130

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