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Proceedings Paper

Higher order modes at FELs: a machine interpretation
Author(s): Peihao Sun; Yanwen Sun; Diling Zhu; Sanghoon Song; Haoyuan Li; Matthieu Chollet; Matthew Seaberg; Jerome B. Hastings; Aymeric Robert; Mark Sutton; Yiping Feng
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Paper 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.

Paper Details

Date Published: 24 April 2019
PDF: 9 pages
Proc. SPIE 11038, X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation V, 1103803 (24 April 2019); doi: 10.1117/12.2522912
Show Author Affiliations
Peihao Sun, SLAC National Accelerator Lab. (United States)
Stanford Univ. (United States)
Yanwen Sun, SLAC National Accelerator Lab. (United States)
Stanford Univ. (United States)
Diling Zhu, SLAC National Accelerator Lab. (United States)
Sanghoon Song, SLAC National Accelerator Lab. (United States)
Haoyuan Li, SLAC National Accelerator Lab. (United States)
Matthieu Chollet, SLAC National Accelerator Lab. (United States)
Matthew Seaberg, SLAC National Accelerator Lab. (United States)
Jerome B. Hastings, SLAC National Accelerator Lab. (United States)
Aymeric Robert, SLAC National Accelerator Lab. (United States)
Mark Sutton, McGill Univ. (Canada)
Yiping Feng, SLAC National Accelerator Lab. (United States)


Published in SPIE Proceedings Vol. 11038:
X-Ray Free-Electron Lasers: Advances in Source Development and Instrumentation V
Thomas Tschentscher; Luc Patthey; Kai Tiedtke; Marco Zangrando, Editor(s)

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