|WEPP039||Single-Shot Diagnostics of Microbunched Electrons in Laser-Driven Plasma Accelerators and Free-Electron Lasers||628|
Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The need for single-shot diagnostics of the periodic longitudinal density modulation of relativistic electrons at the resonant wavelength (microbunching) in a free-electron laser (FEL) or at broadband visible wavelengths as in a laser-driven plasma accelerator (LPA) has been reaffirmed. In the self-amplified spontaneous emission (SASE) FEL case, statistical fluctuations in the microbunching occur in the startup-from-noise process. In the LPA, the plasma itself is chaotic and varies shot to shot. Fortunately, we have shown that coherent optical transition radiation (COTR) techniques, can assess beam size, divergence, spectral evolution, and z-dependent gain (100, 000) of microbunched electrons in a past SASE FEL experiment at 530 nm*. Recently, the application to LPAs has been demonstrated with single-shot near-field (NF) and far-field (FF) COTR imaging done at the exit of an LPA for the first time**. In this case few-micron beam sizes and extensive fringes due to sub-mrad divergences were measured based on point-spread-function effects and an analytical model for COTR interferometry, respectively. A proposed diagnostics application at 266 nm to pre-bunched beams is also described.
*A.H. Lumpkin et al., Phys. Rev. Lett. 88, No.23, 234801 (2002).
**A.H. Lumpkin, M. LaBerge, D.W. Rule, et al., Proceedings of AAC18, (IEEE), 2019.
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP039|
|About •||paper received ※ 10 September 2019 paper accepted ※ 11 September 2019 issue date ※ 10 November 2019|
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