Higher order modes at FELs: a machine interpretation

Peihao Sun; Yanwen Sun; Diling Zhu; Sanghoon Song; Haoyuan Li; Matthieu Chollet; Matthew Seaberg; Jerome B. Hastings; Aymeric Robert; Mark Sutton; Yiping Feng

doi:10.1117/12.2522912

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24 April 2019 Higher order modes at FELs: a machine interpretation

Peihao Sun, Yanwen Sun, Diling Zhu, Sanghoon Song, Haoyuan Li, Matthieu Chollet, Matthew Seaberg, Jerome B. Hastings, Aymeric Robert, Mark Sutton, Yiping Feng

Author Affiliations +

Proceedings Volume 11038, X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation V; 1103803 (2019) https://doi.org/10.1117/12.2522912
Event: SPIE Optics + Optoelectronics, 2019, Prague, Czech Republic

Abstract

In X-ray Free-Electron Lasers (FELs), intense and coherent pulses are generated via amplification of the undulator radiation from micro-bunched electron pulses. The initial radiation is spontaneous and intrinsically stochastic, thus causing shot-to-shot fluctuations in the intensity, pointing, and spatiotemporal profile of the X-ray beam. In this work, we use deep neural networks to investigate the fluctuations in X-ray beam profiles, thereby obtaining statistical information on the lasing process. A supervised model was built to classify X-ray images, and an unsupervised one to study the distribution of beam profiles. We have found that round-shaped profiles appear more often with increasing monochromator bandwidth, suggesting that some round-shaped images can be superpositions of higher-order modes. Our results also suggest that the X-ray beam continues to evolve past the FEL saturation length towards a round-shaped beam profile.

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Peihao Sun, Yanwen Sun, Diling Zhu, Sanghoon Song, Haoyuan Li, Matthieu Chollet, Matthew Seaberg, Jerome B. Hastings, Aymeric Robert, Mark Sutton, and Yiping Feng "Higher order modes at FELs: a machine interpretation", Proc. SPIE 11038, X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation V, 1103803 (24 April 2019); https://doi.org/10.1117/12.2522912

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