Author: Bock, M.K.
Paper Title Page
MOOAA03 Fast Feedback Strategies for Longitudinal Beam Stabilization 26
 
  • S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • W. Jałmużna
    TUL-DMCS, Łódź, Poland
  • G. Lichtenberg, H. Werner
    TUHH, Hamburg, Germany
 
  The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method *. The combination of both approaches will be presented and possible advantages are discussed.
* C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.
 
slides icon Slides MOOAA03 [0.544 MB]  
 
WEPPD049 Characterization of the Engineered Photodiode-based Fiber Link Stabilization Scheme for Optical Synchronization Systems 2627
 
  • T. Lamb, M.K. Bock, M. Felber, F. Ludwig, H. Schlarb, S. Schulz
    DESY, Hamburg, Germany
  • S. Jabłoński
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
 
  Pulsed optical synchronization systems are used in modern FELs like FLASH and will be used in the upcoming European XFEL. Their purpose is to distribute synchronization signals with femtosecond stability throughout the machine. Optical fibers are used to transport the pulses carrying the timing information to their end-stations. These fibers have to be continuously delay stabilized in order to achieve the desired precision. In this paper, a photodiode-based detector to measure the drifts of the fiber delay and allows their active correction is presented. Promising results from a first prototype setup of a photodiode-stabilized optical fiber link were the starting point for an engineering of this concept. An enclosure with free-space optics, fiber optics and integrated electronics for the detector, operating at 9.75 GHz, was designed. This unit includes all required parts to stabilize four fiber links. It allows to investigate the temperature sensitivity of the detector. Furthermore, results from drift measurements carried out with a two channel engineered detector are presented in this paper.