MC6: Beam Instrumentation, Controls, Feedback and Operational Aspects
T25 Lasers
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WEPAB289 Machine Learning Based Spatial Light Modulator Control for the Photoinjector Laser at FLUTE 3332
 
  • C. Xu, E. Bründermann, A.-S. Müller, M.J. Nasse, A. Santamaria Garcia, C. Sax, C. Widmann
    KIT, Karlsruhe, Germany
  • A. Eichler
    DESY, Hamburg, Germany
 
  Funding: C. Xu acknowledges the support by the DFG-funded Doctoral School "Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology".
FLUTE (Ferninfrarot Linac- und Test-Experiment) at KIT is a compact linac-based test facility for novel accelerator technology and a source of intense THz radiation. FLUTE is designed to provide a wide range of electron bunch charges from the pC- to nC-range, high electric fields up to 1.2 GV/m, and ultra-short THz pulses down to the fs-timescale. The electrons are generated at the RF photoinjector, where the electron gun is driven by a commercial titanium sapphire laser. In this kind of setup the electron beam properties are determined by the photoinjector, but more importantly by the characteristics of the laser pulses. Spatial light modulators can be used to transversely and longitudinally shape the laser pulse, offering a flexible way to shape the laser beam and subsequently the electron beam, influencing the produced THz pulses. However, nonlinear effects inherent to the laser manipulation (transportation, compression, third harmonic generation) can distort the original pulse. In this paper we propose to use machine learning methods to manipulate the laser and electron bunch, aiming to generate tailor-made THz pulses. The method is demonstrated experimentally in a test setup.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB289  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 26 August 2021  
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WEPAB290 Pointing Stabilization Algorithms Explored and Implemented with the Low Energy RHIC Electron Cooling Laser 3336
 
  • L.K. Nguyen
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The electron beam for the Low Energy RHIC electron Cooler (LEReC) at Brookhaven National Laboratory (BNL) is generated by a high-power fiber laser illuminating a photocathode, with a total propagation distance of 34 m separating the laser output and the photocathode. This propagation is facilitated by three independent laser tables that have varying responses to changes in time of day, weather, and season. Alignment drifts induced by these environmental changes are mitigated by an active "slow" pointing stabilization system found along the length of the transport, and this in-house system was commissioned as part of the full laser transport in 2019, as previously reported*. In 2020, the system became fully operational alongside LEReC, the world’s first electron cooler in a collider, and helped establish the transverse stability of the electron beam required for cooling. A summary of the different slow stabilization algorithms, which were continually refined during the run in order to achieve long-term center-of-mass stability of the laser spot on the photocathode to within 10 microns RMS, is provided.
* L. K. Nguyen et al., "Active Pointing Stabilization Techniques Applied to the Low Energy RHIC Electron Cooling Laser Transport at BNL", presented at NAPAC’19, paper THYBA6.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB290  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 24 August 2021  
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