WEOA —  Longitudinal diagnostic and synchronization   (12-Sep-18   09:00—10:30)
Chair: M. Ferianis, Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
Paper Title Page
Femtosecond Synchronization of PAL-XFEL  
  • C. Kim, H.-S. Kang, I.S. Ko, C.-K. Min
    PAL, Pohang, Kyungbuk, Republic of Korea
  The PAL-XFEL achieved a 20 fs jitter in the bunch arrival time at the end of undulators and its pump-probe system, which is extremely useful for maintaining a high stability of machine and time-resolved experiments with high time resolution. A low phase noise timing system and high stability high power RF system enable this low jitter. The measurement result shows 10 fs jitter of bunch arrival time at the injector and it increased ~ 20 fs due to the bunch energy variation. The possibility of improving the final jitter is described based on the optimization of bunch compressors and a longitudinal feedback.  
slides icon Slides WEOA01 [9.603 MB]  
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WEOA02 Optical Investigation to Minimize the Electron Bunch Arrival-time Jitter Between Femtosecond Laser Pulses and Electron Bunches for Laser-Driven Plasma Wakefield Accelerators 332
  • S. Mattiello, A. Penirschke
    THM, Friedberg, Germany
  • H. Schlarb
    DESY, Hamburg, Germany
  Funding: The work of S. Mattiello is supported by the German Federal Ministry of Education and Research (BMBF) within the Project ' MAKE-PWA.
In a laser driven plasma based particle accelerators a stable synchronization of the electron bunch and of the plasma wakefield in the range of less than 2 fs is necessary in order to optimize the acceleration. For this purpose we are developing a new shot to shot feedback system with a time resolution of less than 1 fs. As a first step, stable THz pulses are generated by optical rectification of a fraction of the plasma generating high energy laser pulses in a nonlinear lithium niobate crystal. It is planed that the generated THz pulses will energy modulate the electron bunches shot to shot before the plasma to achieve the time resolution of 1 fs. In this contribution we systematically investigate the influence of the optical properties as well as the theoretical description of the THz generation on the conversion efficiency of the generation of short THz pulses in undepleted approximation. We compare different approximations for the modeling of the generation dynamics and of the dielectric function in order to investigate the importance of a detailed description of the optical properties. First results by considering intensity decreasing of the laser pump will be presented.
*The feedback system will be tested at the Accelerator R&D facility SINBAD (Short Innovative Bunches and Accelerators at DESY).
slides icon Slides WEOA02 [1.605 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOA02  
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WEOA03 First Electro-Optical Bunch Length Measurements from the European XFEL 338
  • B. Steffen, M.K. Czwalinna, C. Gerth, P. Peier
    DESY, Hamburg, Germany
  Three electro-optical bunch length detection systems based on spectral decoding have been installed and are being commissioned at the European XFEL. The systems are capable of recording individual longitudinal bunch profiles with sub-picosecond resolution at a bunch repetition rate 1.13 MHz. Bunch lengths and arrival times of entire bunch trains with single-bunch resolution have been measured as well as jitter and drifts for consecutive bunch trains. In this paper, we present first measurement results for the electro-optical detection system located after the second bunch compressor. A preliminary comparison with data from the bunch arrival-time monitor shows good agreement.  
slides icon Slides WEOA03 [4.496 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOA03  
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WEOA04 The Application of Beam Arrival Time Measurement at SXFEL 342
  • S.S. Cao, J. Chen, Y.B. Leng, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
  Shanghai soft X-ray free electron laser (SXFEL) is able to generate high brightness and ultra-short light pulses. The generation of the light sources relies on the synchronization between seeded laser and electron bunch. Beam arrival time play an important role to keep the synchronization. For the SXFEL, a beam arrival time resolution under 100 fs is required. In this paper, the application of beam arrival time measurement scheme on SXFEL has been presented. The whole BAM system consists of four parts: beam arrival time monitor, electronic front-end, signal acquisition system, and high-level signal processing and presentation. Currently, four sets of beam arrival time monitors (BAMs) have been installed in the SXFEL and distributed in four different locations. The relevant beam arrival time experiment and beam flight time experiment based on the dual-cavities mixing method have also been performed so as to evaluate and analyze the beam status.  
slides icon Slides WEOA04 [4.588 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2018-WEOA04  
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