Keyword: flattop
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TUP002 Progress in Preparing a Proof-of-Principle Experiment for THz SASE FEL at PITZ laser, FEL, undulator, experiment 41
 
  • X. Li, P. Boonpornprasert, Y. Chen, G.Z. Georgiev, J.D. Good, M. Groß, P.W. Huang, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
 
  A proof-of-princle experiment for a THz SASE FEL is undergoing preparation at the Photo Injector Test facility at DESY in Zeuthen (PITZ), as a prototype THz source for pump-probe experiments at the European XFEL, which could potentially provide up to mJ/pulse THz radiation while maintaining the identical pulse train structure as the XFEL pulses. In the proof-of-principle experiment, LCLS-I undulators will be installed to generate SASE radiation in the THz range of 3-5 THz from electron bunches of 16-22 MeV/c. One key design is to obtain the peak current of nearly 200 A from the heavily charged bunches of a few nC. In this paper, we report our simulation results on the optimization of the space charge dominated beam in the photo injector and the following transport line with two cathode laser setups. Experimental results based on a short Gaussian laser will also be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP002  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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WEP012 THz Spectroscopy with MHz Repetition Rates for Bunch Profile Reconstructions at European XFEL radiation, FEL, electron, undulator 350
 
  • N.M. Lockmann, C. Gerth, B. Schmidt, S. Wesch
    DESY, Hamburg, Germany
 
  The European X-ray Free-Electron Laser generates most powerful and brilliant X-ray laser pulses. Exact knowledge about the longitudinal electron bunch profile is crucial for the operation of the linear accelerator as well as for photon science experiments. The only longitudinal diagnostic downstream of the main linac is based on spectroscopy of diffraction radiation (DR). The spectral intensity of the DR in the THz and infrared regime is monitored by a four-staged grating spectrometer and allows non-invasive bunch length characterization based on form factor measurements in the range 0.7 - 60 THz. As the readout and signal shaping electronics of the spectrometer allow MHz readout rates, the longitudinal bunch profile of all bunches inside the bunch train can be characterized non-invasively and simultaneously to FEL operation. In this paper, form factor measurements along the bunch train will be described and presented as well as the resulting reconstructed current profiles.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP012  
About • paper received ※ 20 August 2019       paper accepted ※ 29 August 2019       issue date ※ 05 November 2019  
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WEP013 Fast Kicker System for European XFEL Beam Distribution kicker, FEL, feedback, septum 353
 
  • F. Obier, W. Decking, M. Hüning, J. Wortmann
    DESY, Hamburg, Germany
 
  A special feature of the European XFEL X-ray laser is the possibility to distribute the electron bunches of one beam pulse to different free-electron laser (FEL) beam-lines. This is achieved through a combination of kickers and a Lambertson DC septum. The integration of a beam abort dump allows a flexible selection of the bunch pattern at the FEL experiment, while the superconducting linear accelerator operates with constant beam loading. The driver linac of the FEL can deliver up to 600 µs long bunch trains with a repetition rate of 10 Hz and a maximum energy of 17.5 GeV. The FEL process poses very strict requirements on the stability of the beam position and hence on all upstream magnets. It was therefore decided to split the beam distribution system into two kicker systems, long pulse kickers with very stable amplitude (flat-top) and relatively slow pulses and fast stripline kickers with moderate stability but very fast pulses. This contribution gives a brief overview of the fast kicker system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP013  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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WEP014 Long Pulse Kicker for European XFEL Beam Distribution kicker, FEL, timing, septum 357
 
  • F. Obier, W. Decking, M. Hüning, J. Wortmann
    DESY, Hamburg, Germany
 
  A special feature of the European XFEL X-ray laser is the possibility to distribute the electron bunches of one beam pulse to different free-electron laser (FEL) beam-lines. This is achieved through a combination of kickers and a Lambertson DC septum. The integration of a beam abort dump allows a flexible selection of the bunch pattern at the FEL experiment, while the superconducting linear accelerator operates with constant beam loading. The driver linac of the FEL can deliver up to 600 µs long bunch trains with a repetition rate of 10 Hz and a maximum energy of 17.5 GeV. The FEL process poses very strict requirements on the stability of the beam position and hence on all upstream magnets. It was therefore decided to split the beam distribution system into two kicker systems, long pulse kickers with very stable amplitude (flat-top) and relatively slow pulses and fast stripline kickers with moderate stability but very fast pulses. This contribution gives a brief overview of the long pulse kicker system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP014  
About • paper received ※ 20 August 2019       paper accepted ※ 27 August 2019       issue date ※ 05 November 2019  
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WEP050 Status of Chirped Pulse Laser Shaping for the PITZ Photoinjector laser, electron, optics, simulation 437
 
  • C. Koschitzki, Y. Chen, J.D. Good, M. Groß, M. Krasilnikov, G. Loisch, R. Niemczyk, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
  • E. Khazanov, S. Mironov
    IAP/RAS, Nizhny Novgorod, Russia
  • T. Lang, L. Winkelmann
    DESY, Hamburg, Germany
 
  The beam emittance at FEL facilities like European XFEL and FLASH is dominated by the emittance sources in the electron injector. Shaping of the laser pulses that are employed to release electrons from the cathode of a photo injector, was shown in theory to allow improved beam emittance starting from the electron emission process. At the photo injector test facility at DESY in Zeuthen (PITZ) a laser system capable of controlling the temporal and spatial profile of laser pulses is being set up to demonstrate the predicted emittance reduction experimentally. The presentation will show its current capabilities to provide temporally and spatially shaped laser pulses from a pulse shaper operating at infrared (IR) wavelengths. Furthermore, results from a shape preserving conversion into fourth harmonic ultra-violet (UV), as needed for the photo emission process, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP050  
About • paper received ※ 21 August 2019       paper accepted ※ 17 September 2019       issue date ※ 05 November 2019  
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WEP058 Drive Laser Temporal Shaping Techniques for Shanghai Soft X-Ray Free Electron Laser laser, electron, FEL, cathode 466
 
  • X.T. Wang, T. Lan, M. Zhang, W.Y. Zhang
    SINAP, Shanghai, People’s Republic of China
  • L. Feng, B. Liu
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • C.L. Li
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
 
  The design of Shanghai soft X-ray free electron laser (SXFEL) is based on laser driven photocathode, which can provide emittance <2.0 mm’mrad with 500 pC charge. The temporal shape of drive laser has significant influence on the electron beam emittance and brightness. This paper presents the transport line of drive laser system and the temporal shaping techniques for SXFEL. This drive laser produces 8 picosecond 266nm ultraviolet pulses with repetition rate 10Hz. A transverse deflecting cavity was used for indirectly characterizing the laser pulse temporal structure. Here we present the drive laser system with its temporal shaping method, and measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP058  
About • paper received ※ 20 August 2019       paper accepted ※ 28 August 2019       issue date ※ 05 November 2019  
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