Author: Schlarb, H.
Paper Title Page
MOPO038 RF Operation Experience at the European XFEL 109
MOOP09   use link to see paper's listing under its alternate paper code  
 
  • J. Branlard, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hierholzer, M.G. Hoffmann, M. Hoffmann, M. Killenberg, D. Kostin, T. Lamb, L. Lilje, U. Mavrič, M. Omet, S. Pfeiffer, R. Rybaniec, H. Schlarb, Ch. Schmidt, N. Shehzad, V. Vogel, N. Walker
    DESY, Hamburg, Germany
 
  After its successful commissioning which took place during the first half of 2017, the European X-ray free electron laser is in now in regular operation delivering photons to users since September 2017. This paper presents an overview on the experience gathered during the first couple of years of operation. In particular, the focus is set on RF operation, maintenance activities, availability and typical failures. A first look on machine performance in terms of RF and beam stability, energy reach, radiation related investigations and microphonics studies will also be presented.  
slides icon Slides MOPO038 [2.421 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO038  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO039 Status Update of the Fast Energy Corrector Cavity at FLASH 112
 
  • S. Pfeiffer, J. Branlard, Ł. Butkowski, M. Hierholzer, M. Hoffmann, K. Honkavaara, H. Schlarb, Ch. Schmidt, S. Schreiber, M. Vogt, J. Zemella
    DESY, Hamburg, Germany
  • M. Fakhari
    CFEL, Hamburg, Germany
 
  Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 312453.
Linear accelerator facilities driving a free-electron laser require femtosecond precision synchronization between external laser systems and the electron beam. Such high precision is required for pump-probe experiments and also for example for the electron bunch injection into a plasma bubble for laser plasma acceleration. An upgrade of the fast intra-train beam-based feedback system is planned at the Free-Electron Laser FLASH in Hamburg, Germany. This linear accelerator is based on superconducting (SRF) technology operating with pulse trains of maximum 1 MHz bunch repetition rate. Arrival time fluctuations of the electron beam are correctable by introducing small energy modulations prior to the magnetic bunch compressor. This contribution focuses on the design and the characterization of a normal-conducting RF (NRF) cavity with large bandwidth, mandatory to correct fast arrival time fluctuations. The cavity has recently been installed in the FLASH beamline. First measurements with the new cavity will be presented.
 
poster icon Poster MOPO039 [1.884 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO039  
About • paper received ※ 13 September 2018      issue date ※ 18 January 2019  
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MOPO102 Progress of MicroTCA.4 based LLRF System of TARLA 220
 
  • C. Gumus, M. Hierholzer, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  • A.A. Aksoy, A. Aydin, Ç. Kaya
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • O.F. Elcim
    Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
 
  The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave RF operation. DESY is responsible for delivering a turnkey LLRF system based on MicroTCA.4 standard that will be used to control four superconducting (SC) TESLA type cavities as well as the two normal conducting buncher cavities. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. With the usage of ChimeraTK framework, integration to EPICS control system is also implemented. This poster describes the system setup and integration to the existing accelerator environment with hardware and software components along with the latest updates from the facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO102  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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MOPO104 LLRF R&D Towards CW Operation of the European XFEL 223
SPWR026   use link to see paper's listing under its alternate paper code  
 
  • A. Bellandi, V. Ayvazyan, J. Branlard, C. Gumus, S. Pfeiffer, K.P. Przygoda, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz
    DESY, Hamburg, Germany
  • W. Cichalewski
    TUL-DMCS, Łódź, Poland
 
  The ever growing request for machines with a higher average beam pulse rate and also with a relaxed (< 1 MHz) pulse separation calls for superconducting linacs that operate in Long Pulse (LP) or Continuous Wave (CW) mode. For this purpose the European X-ray Free Electron Laser (European XFEL) could be upgraded to add the ability to run in CW/LP mode. Cryo Module Test Bench (CMTB) is a facility used to perform tests on superconducting cavity cryomodules. Because of the interest in upgrading European XFEL to a CW machine, CMTB is now used to perform studies on XM-3, a 1.3 GHz European XFEL-like cryomodule with modified coupling that is able to run with very high quality factor (QL = 10E7…10E8) values. The RF power source allows running the cavities at gradients larger than 16 MV/m. Because of the QL and gradient values involved in these tests, detuning effects like mechanical resonances and microphonics became more challenging to regulate. The goal is then to determine the appropriate set of parameters for the LLRF control system to keep the error to be less than 0.01° in phase and 0.01% in amplitude.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO104  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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MOPO121 Large-Scale Optical Synchronization System of the European XFEL 253
 
  • J.M. Müller, M. Felber, T. Kozak, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
    DESY, Hamburg, Germany
 
  At the European XFEL, a facility-wide optical synchronization system providing a femtosecond-stable timing reference at more than 40 end-stations had been developed and installed. The system is based on an ultra-stable, low-noise laser oscillator, whose signals are distributed via actively length-stabilized optical fibers to the different locations across the accelerator and experimental areas. There, it is used to locally re-synchronize radio frequency signals, to precisely measure the arrival time of the electron beam for fast beam-based feedbacks, and to phase-lock optical laser systems for electron bunch generation, beam diagnostics and user pump-probe experiments with femtosecond temporal resolution. In this paper, we present the system’s architecture and discuss design choices to realize an extensible, large-scale synchronization infrastructure for accelerators that meets reliability, maintainability as well as the performance requirements. Furthermore, the latest performance result of an all-optically synchronized laser oscillator is shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MOPO121  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO017 The New Light Ion Injector for NICA 362
 
  • B. Koubek, M. Basten, H. Höltermann, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede
    BEVATECH, Frankfurt, Germany
  • A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • C. K. Kampmeyer, H. Schlarb
    DESY, Hamburg, Germany
 
  Within the upgrade scheme of the injection complex of the NICA project and after a successful beam commissioning of a heavy ion linac, Bevatech GmbH will build a first part of a new light ion linac as an injector for the Nuclotron ring. The linac will provide a beam of polarised protons and light ions with a mass to charge ratio up to 3 and an energy of 7 MeV/u. The mandate of the Linac does not only include the hardware for the accelerating structures, focusing magnets and beam diagnostic devices, but also the LLRF control soft- and hardware based on the MicroTCA.4 standard in collaboration with the MicroTCA Technology Lab at DESY. An overview of the Linac is presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO017  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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TUPO029 Highlights of the XM-3 Cryomodule Tests at DESY 388
 
  • J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gumus, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
    DESY, Hamburg, Germany
  • W. Cichalewski
    TUL-DMCS, Łódź, Poland
 
  To investigate the feasibility of the continuous wave (cw) upgrade of the European XFEL (E-XFEL) DESY, on-going tests are performed on E-XFEL prototype and production cryomodules since 2011. For these studies, DESY’s Cryo-Module Test Bench (CMTB) has been equipped with a 105 kW cw operating IOT in addition to the 10MW pulsed klystron, making CMTB a very flexible test stand, enabling both cw and pulse operation. For these tests, E-XFEL-like LLRF electronics is used to stabilize amplitude and phase of the voltage Vector Sum (VS) of all 8 cavities of the cryomodule under test. The cryomodule most often tested is the pre-series XM-3, unique since it is housing one fine grain niobium and seven large grain niobium cavities. In autumn 2017, additional spacers were installed on all 8 input couplers to increase the maximum reachable loaded quality factor Ql beyond 2·107. With higher Ql, up to 6·107 for 6 cavities and 2.7·107 for 2 cavities, we have investigated the VS stability and SRF-performance of this cryomodule under various conditions of cooling down rate and operation temperature 1.65K, 1.8K and 2K, at gradients up to ca. 18MV/m. The results of these tests are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO029  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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TUPO132 Implementation of the Beam Loading Compensation Algorithm in the LLRF System of the European XFEL 594
 
  • Ł. Butkowski, J. Branlard, M. Omet, R. Rybaniec, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
 
  In the European XFEL, a maximum number of 2700 electron bunches per RF pulse with beam currents up to 4.5mA can be accelerated. Such large beam currents can cause a significant drop of the accelerating gradients, which results in large energy changes across the macro-pulse. But, the electron bunch energies should not deviate from the nominal energy to guarantee stable and reproducible generation of photon pulses for the European XFEL users. To overcome this issue, the Low Level RF system (LLRF) compensates in real-time the beam perturbation using a Beam Loading Compensation algorithm (BLC) minimizing the transient gradient variations. The algorithm takes the charge information obtained from beam diagnostic systems e.g. Beam Position Monitors (BPM) and information from the timing system. The BLC is a part of the LLRF controller implemented in the FPGA. The article presents the implementation of the algorithm in the FPGA and shows the results achieved with the BLC in the European XFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO132  
About • paper received ※ 11 September 2018      issue date ※ 18 January 2019  
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