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Loehl, F.

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MOPAN020 Status of the Laser Master Oscillator System at FLASH 191
  • A. Winter, F. Loehl, H. Schlarb, P. Schmuser
    DESY, Hamburg
  • W. J. Jalmuzna
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw
  An optical synchronization system based on the timing-stabilized distribution of ultra-short optical pulses has been proposed for next generation light sources, e.g. the European XFEL. The concept will be implemented and tested at FLASH at DESY. This paper describes the status of the optical master oscillator, which consists of two mode-locked Erbium-doped fiber lasers running in parallel.  
WEPMN012 Beam Loading Compensation Using Real Time Bunch Charge Information from a Toroid Monitor at FLASH 2074
  • E. Vogel, C. Gerth, W. Koprek, F. Loehl, D. Noelle, H. Schlarb, T. Traber
    DESY, Hamburg
  Funding: Deutsches Elektronen-Synchrotron - DESY

At pulsed linear accelerators, fast proportional rf control compensates beam loading sufficiently for single or a few bunches. In the case of long bunch trains, additional measures have to be taken commonly by adding a compensation signal to the rf drive signals calculated from the predicted beam intensity. In contrast to predictive methods, techniques based on real time beam measurements are sensitive to fast changes of the beam intensity and bunch patterns. At FLASH we apply a beam loading compensation scheme based on toroid monitor signals. This paper presents the compensation scheme, the calibration procedure and the effect on the beam.

THPAN026 Beam Profile Measurements and Analysis at FLASH 3283
  • E. Prat, W. Decking, T. Limberg, F. Loehl
    DESY, Hamburg
  • K. Honkavaara
    Uni HH, Hamburg
  FLASH (Free Electron LASer in Hamburg) is a SASE FEL user facility at DESY, Hamburg. It serves also as a pilot project for the European XFEL. Although the slice emittance is a more appropriate parameter to characterize the SASE process, the projected emittance is a good indicator of the electron beam quality which can be measured in an easy and fast way. In this paper we present measurements of the projected emittance along FLASH. We also analyze the effect of the dispersion on transverse electron beam profiles.  
FROAC04 Sub-10 Femtosecond Stabilization of a Fiber Link Using a Balanced Optical Cross Correlator 3804
  • F. Loehl, H. Schlarb
    DESY, Hamburg
  • J. Chen, F. X. Kaertner, J. Kim, F. Wong
    MIT, Cambridge, Massachusetts
  • J. M. Mueller
    TUHH, Hamburg
  Synchronization of various components with fs stability is needed for the operation of free-electron-lasers such as FLASH or the European XFEL. One possibility to realize a high precision synchronization is to use a mode-locked Er-doped fiber laser as a master clock and to distribute ultra short laser pulses inside the machine using actively stabilized fiber links. In this paper we demonstrate the stabilization of a 300 m long fiber link with a self-aligned balanced cross-correlator using a single type II phase-matched PPKTP crystal. This approach allowed us to reduce the timing jitter added by the link to below 10 fs.  
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