Author: Geloni, G.
Paper Title Page
Study of an External Laser Seeding at the European XFEL  
  • T. Tanikawa, G. Geloni, S. Karabekyan, S. Serkez, S.I. Tomin
    XFEL. EU, Schenefeld, Germany
  Several XFEL facilities are currently in the commissioning or operation phase and have opened new exciting scientific opportunities. In May 2017, the European XFEL successfully achieved a first lasing. Recently, most of the FEL facilities are going to invest (or have already invested) in advanced schemes to increase the longitudinal coherence properties of radiation compared to SASE. As one of the techniques, an external laser seeding is currently applicable at soft X-ray facilities, in a frequency range where external seed pulses are powerful enough to overcome the SASE shot noise. However, these techniques are now also being considered at several hard X-ray FEL facilities and aim for the production of nearly Fourier-limited pulses up to the keV range. At the European XFEL, the challenge of HGHG and EEHG options is the usage of very high electron beam energy. In this presentation, we will report the preliminary simulation results of the external laser seeding feasibility at the European XFEL.  
MOP008 Status of the Hard X-Ray Self-Seeding Project at the European XFEL 1
  • G. Geloni, S. Karabekyan, L. Samoylova, S. Serkez, H. Sinn
    XFEL. EU, Hamburg, Germany
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • W. Decking, C. Engling, N. Golubeva, V. Kocharyan, B. Krause, S. Lederer, S. Liu, A. Petrov, E. Saldin, T. Wohlenberg
    DESY, Hamburg, Germany
  • X. Dong
    European X-Ray Free-Electron Laser Facility GmbH, Schelefeld, Germany
  • D. Shu
    ANL, Argonne, Illinois, USA
  A Hard X-ray Self-Seeding setup is currently under realization at the European XFEL, and will be ready for installation in 2018. The setup consists of two single-crystal monochromators that will be installed at the SASE2 undulator line. In this contribution, after a short summary of the physical principles and of the design, we will discuss the present status of the project including both electron beam and X-ray optics hardware. We will also briefly discuss the expected performance of the setup, which is expected to produce nearly Fourier-limited pulses of X-ray radiation with increased brightness compared to the baseline of the European XFEL, as well as possible complementary uses of the two electron chicanes.  
poster icon Poster MOP008 [2.440 MB]  
MOP037 Opportunities for Two-Color Experiments at the SASE3 Undulator Line of the European XFEL 1
  • S. Serkez, G. Geloni, T. Mazza, M. Meyer
    XFEL. EU, Hamburg, Germany
  • V. Kocharyan, E. Saldin
    DESY, Hamburg, Germany
  As is well known, the installation of a simple magnetic chicane in the baseline undulator of an XFEL allows for producing two-color FEL pulses. In this work we discuss the possibility of applying this simple and cost-effective method at the SASE3 soft X-ray beamline of the European XFEL. We consider upgrades of this method that include the further installation of a mirror chicane. We also discuss the scientific interest of this upgrade for the Small Quantum Systems (SQS) instrument, in connection with the high-repetition rate of the European XFEL, and we provide start-to-end simulations up to the radiation focus on the sample, proving the feasibility of our concept. Our proposed setup has been recently funded by the Finnish Research Infrastructure (FIRI) and will be built at SASE3 in 2020-2021.  
poster icon Poster MOP037 [1.844 MB]  
TUP004 Longitudinal Phase Space Optimization for the Hard X-ray Self-Seeding 1
  • S. Liu, W. Decking, G. Feng, V. Kocharyan, I. Zagorodnov
    DESY, Hamburg, Germany
  • G. Geloni, S. Serkez
    XFEL. EU, Schenefeld, Germany
  For the implementation of Hard X-ray Self-Seeding (HXRSS) at European XFEL, short electron-beam bunches (FWHM ≤ 50 fs) are preferred to mitigate spatio-temperal coupling effect and to fit to the seeding bump width. Therefore, operations with low charges (< 250 pC) are preferred. Longitudinal phase-space optimization has been performed for the 100 pC case by flattening the current distribution. Start-to-end simulations show that, with the optimized distribution, for the photon energy of 14.4 keV, the HXRSS output power, pulse energy and spectral intensity can be increased by a factor of approximately 2 as compared to the nominal working point.  
Generation of Sub-fs X-Ray Pulses at the European XFEL  
  • S. Serkez, G. Geloni, S. Karabekyan, M. Lederer, S.I. Tomin
    XFEL. EU, Hamburg, Germany
  • G. Feng, V. Kocharyan, E. Saldin, I. Zagorodnov
    DESY, Hamburg, Germany
  • A. Kalaydzhyan
    CFEL, Hamburg, Germany
  Time-resolved studies of free electron lasers are of a great importance. The resulting temporal resolution of the user measurements is determined by FEL pulse duration. Here we investigate possibilities to obtain sub-fs-long pulses at the European XFEL. Installation of the drive laser, modulator and magnetic chicane before the baseline undulator is required.  
poster icon Poster TUP044 [0.680 MB]  
TUP045 Interference-Based Ultrafast Polarization Control at Free Electron Lasers 1
  • S. Serkez, G. Geloni
    XFEL. EU, Hamburg, Germany
  • E. Saldin
    DESY, Hamburg, Germany
  We present a scheme to generate two distinct FEL pulses with different polarization properties and down to 50 fs-order temporal separation. The scheme is based on installation of two consecutive helical undulators, a corrugated structure and emittance spoiler on top of a baseline variable gap undulator, and is exemplified on the SASE3 beamline of the European XFEL. Good temporal coherence by either self or external seeding is preferable. Our schemes can be used for pump-probe experiments and in combination with the "twin-bunch" technique.  
poster icon Poster TUP045 [0.568 MB]  
Study of a Superconducting THz Undulator at the European XFEL  
  • T. Tanikawa, G. Geloni, S. Karabekyan
    XFEL. EU, Schenefeld, Germany
  • V. B. Asgekar, M. Gensch
    HZDR, Dresden, Germany
  • S. Casalbuoni
    KIT, Eggenstein-Leopoldshafen, Germany
  The European XFEL has successfully achieved a first lasing in May 2017. Meanwhile, a THz radiation for pump-probe experiments etc. is under consideration at the European XFEL using laser-based and/or accelerator-based techniques. A superconducting THz undulator as an afterburner is one option, but a challenge to this approach is the usage of very high electron-beam energy up to 17.5 GeV and the requirement of a high magnetic field. In this presentation, we will report the preliminary study of the THz undulator design and the radiation properties at the European XFEL.