Author: Branlard, J.
Paper Title Page
MOC3O07 Low Level RF Control Implementation and Simultaneous Operation of Two FEL Undulator Beamlines at FLASH 1
 
  • V. Ayvazyan, S. Ackermann, J. Branlard, B. Faatz, M.K. Grecki, O. Hensler, S. Pfeiffer, H. Schlarb, Ch. Schmidt, M. Scholz, S. Schreiber
    DESY, Hamburg, Germany
  • A. Piotrowski
    FastLogic Sp. z o.o., Łódź, Poland
 
  The Free-Electron Laser in Hamburg (FLASH) is a user facility delivering femtosecond short radiation pulses in the wavelength range between 4.2 and 45 nm using the SASE principle. The tests performed in the last few years have shown that two FLASH undulator beamlines can deliver FEL radiation simultaneously to users with a large variety of parameters such as radiation wavelength, pulse duration, intra-bunch spacing etc. FLASH has two injector lasers on the cathode of the gun to deliver different bunch trains with different charges, needed for different bunch lengths. Because the compression settings depend on the charge of bunches the low level RF system needs to be able to supply different compression for both beamlines. The functionality of the controller has been extended to provide intra-pulse amplitude and phase changes while maintaining the RF field amplitude and the phase stability requirements. The RF parameter adjustment and tuning for RF gun and accelerating modules can be done independently for both laser systems. Having different amplitudes and phases within the RF pulse in several RF stations simultaneous lasing of both systems has been demonstrated.  
slides icon Slides MOC3O07 [4.640 MB]  
 
MOPGF079 European XFEL Cavities Piezoelectric Tuners Control Range Optimization 1
 
  • W. Cichalewski, A. Napieralski
    TUL-DMCS, Łódź, Poland
  • J. Branlard, Ch. Schmidt
    DESY, Hamburg, Germany
 
  The piezo based control of the superconducting cavity tuning has been under the development over last years. Automated compensation of Lorentz force detuning of FLASH and European X-FEL resonators allowed to maintain cavities in resonance operation even for high acceleration gradients (in range of 30 MV/m). It should be emphasized that cavity resonance control consists of two independent subsystems. First of all the slow motor tuner based system can be used for slow, wide range mechanical tuning (range of hundreds of kHz). Additionally the piezo tuning system allows for fine, dynamic compensation in a range of ~1 kHz. In mentioned pulse mode experiments (like FLASH), the piezo regulation budget should be preserved for in-pulse detuning control. In order to maintain optimal cavity frequency adjustment capabilities slow motor tuners should automatically act on the static detuning component at the same time. This paper presents work concerning development, implementation and evaluation of automatic superconducting cavity frequency control towards piezo range optimization. FLASH and X-FEL dedicated cavities tuning control experiences are also summarized.  
poster icon Poster MOPGF079 [0.932 MB]  
 
WEPGF029 High Level Software Structure for the European XFEL LLRF System 1
 
  • Ch. Schmidt, V. Ayvazyan, J. Branlard, Ł. Butkowski, O. Hensler, M. Killenberg, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb
    DESY, Hamburg, Germany
  • W. Cichalewski, F. Makowski
    TUL-DMCS, Łódź, Poland
  • A. Piotrowski
    FastLogic Sp. z o.o., Łódź, Poland
 
  The Low level RF system for the European XFEL is controlling the accelerating RF fields in order to meet the specifications of the electron bunch parameters. A hardware platform based on the MicroTCA.4 standard has been chosen, to realize a reliable, remotely maintainable and high performing integrated system. Fast data transfer and processing is done by field programmable gate arrays (FPGA) within the crate, controlled by a CPU via PCIe communication. In addition to the MTCA system, the LLRF comprises external supporting modules also requiring control and monitoring software. In this paper the LLRF system high level software used in E-XFEL is presented. It is implemented as a semi-distributed architecture of front end server instances in combination with direct FPGA communication using fast optical links. Miscellaneous server tasks have to be executed, e.g. fast data acquisition and distribution, adaptation algorithms and updating controller parameters. Furthermore the inter-server data communication and integration within the control system environment as well as the interface to other subsystems are described.