Facilities - Progress
operational experiences
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MOFAA2 Operation of the European XFEL Towards the Maximum Energy 9
 
  • M. Omet, V. Ayvazyan, J. Branlard, S. Choroba, W. Decking, V.V. Katalev, D. Kostin, L. Lilje, P. Morozov, Y. Nachtigal, H. Schlarb, V. Vogel, N. Walker, B. Yildirim
    DESY, Hamburg, Germany
 
  After the initial commissioning of the available 25 radio frequency (RF) stations of the European XFEL (RF gun, A1, AH1 and stations A2 through A23) a maximum electron beam energy of 14.5 GeV was achieved, 3 GeV short of the design energy of 17.5 GeV. In order to tackle this problem, the Maximum Gradient Task Force (MGTF) was formed. In the scope of the work of the MGTF, RF stations A6 through A25 (linac L3) were systematically investigated and voltage-limiting factors of the SRF accelerating modules and their RF distribution system were identified and improved. As a result, the design electron beam energy was exceeded at 17.6 GeV on the 18.7.2018. Beside this an overview over the regular RF operation at the European XFEL is given.  
slides icon Slides MOFAA2 [5.695 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA2  
About • paper received ※ 21 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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MOFAB6
More than 15 Years of CW SRF Operation at ELBE  
 
  • A. Arnold, M. Freitag, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, J. Teichert, R. Xiang
    HZDR, Dresden, Germany
 
  ELBE is a compact, accelerator-driven photon and particle source. Since 2001 it is operated as a user facility, providing more than 5500 hours of beam time each year. The electron accelerator is based on four superconducting 9-cell TESLA cavities that are driven in full CW operation to accelerate an average current of 1 mA up to beam energies of 40 MeV. The first part of the talk will summarize our experiences of operating TESLA cavities in CW. In detail, this includes their performance and attempts to improve it, as well as investigations on limitations. Additionally, we will discuss several issues that are related to the high average RF as well as beam power and we will present appropriate measures to protect the machine. In this regard, a resonant ring for RF component tests up to 100 kW was set up. The second part of the talk will focus on the development and operation of our SRF guns that are designed to produce short bunches with high charges and repetition rates of 1 MHz and beyond. Recently, SRF gun II was successfully transferred into routine user operation and delivers now more than 200 pC at 100 kHz to the experiment. First convincing results will be presented.  
slides icon Slides MOFAB6 [13.841 MB]  
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WETEB3 CEBAF C100 Fault Classification based on Time Domain RF Signals 763
 
  • T. Powers, A.D. Solopova
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The CEBAF 12 GeV upgrade project, which was completed and commissioned in 2014, included the construction and installation of 80 new 7-cell superconducting cavities that were configured in 10 cryomodules. In 2018, the software and hardware in the digital low level RF systems were configured such that a fault would trigger an acquisition process which records waveform records of 17 of the RF signals for each of the 8 cavities within the cryomodule for subsequent analysis. These waveforms are especially useful in C100 cryomodules as there is a 10% mechanical coupling between adjacent cavities. When one cavity has a fault and the gradient is reduced quickly, it will mechanically deform due relaxation of the Lorentz force effects. This deformation change causes perturbations in the adjacent cavities which, in turn, causes a cascade of cavity faults that are difficult to understand without the time domain data. This contribution will describe the types of faults encountered during operation and their signatures in the time domain data, as well as how is being used to modify the setup of the machine and implement improvements to the cryomodules.
 
slides icon Slides WETEB3 [3.169 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB3  
About • paper received ※ 21 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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THP023 RF Commissioning of the CBETA Main Linac Cryomodule 881
SUSP017   use link to see paper's listing under its alternate paper code  
 
  • N. Banerjee, J. Dobbins, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, C.W. Miller, P. Quigley, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was performed through the support of New York State Energy Research and Development Agency (NYSERDA).
The Cornell BNL ERL Test Accelerator (CBETA) employs a superconducting Main Linac Cryomodule in order to perform multi-turn energy recovery operation. Optimizing the field stability of the low bandwidth SRF cavities in the presence of microphonics with limited available RF power is a challenging task. Despite of this, the Main Linac Cryomodule has been successfully used in CBETA to impart a maximum energy gain of 54 MeV, well above the energy gain requirement of CBETA. In this paper, we present an overview of our RF commissioning procedure including automatic coarse tuning, measurement of DAC and phase offsets. We further detail our microphonics measurements from our most recent run period.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP023  
About • paper received ※ 23 June 2019       paper accepted ※ 29 June 2019       issue date ※ 14 August 2019  
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THP025 Overview of Superconducting RF Cavity Reliability at Diamond Light Source 885
THP024   use link to see paper's listing under its alternate paper code  
 
  • C. Christou, P. Gu, P.J. Marten, S.A. Pande, A.F. Rankin, D. Spink, L.T. Stant, A. Tropp
    DLS, Oxfordshire, United Kingdom
 
  Diamond Light Source has been providing beam for users since January 2007. The electron beam in the storage ring is normally driven by two superconducting CESR-B cavities, with two similar cavities available as spares. Day-to-day reliability of the cavities, measured by storage ring MTBF, has improved enormously over the years. A full analysis of how this improvement has been achieved is given, with particular attention paid to cavity voltage and vacuum pressure management, and the scheduling and procedure of cavity conditioning. The benefits and risks of full and partial warm-ups of the cavities are discussed, and details and impacts of cavity failure and repair are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP025  
About • paper received ※ 21 June 2019       paper accepted ※ 01 July 2019       issue date ※ 14 August 2019  
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THP026 Initial Operation of the LCLS-II Electron Source 891
 
  • C. Adolphsen, A.L. Benwell, G.W. Brown, M.P. Dunning, S. Gilevich, K. Grouev, X. Liu, J.F. Schmerge, T. Vecchione, F.Y. Wang, F. Zhou
    SLAC, Menlo Park, California, USA
  • G. Huang, M.J. Johnson, T.H. Luo, F. Sannibale, S.P. Virostek
    LBNL, Berkeley, California, USA
 
  Funding: This work supported under DOE Contract DE-AC02-76SF00515
The Early Injector Commissioning program for LCLS-II aims to demonstrate CW electron beam production this year in the first two meters of the injector that includes the room-temperature 185.7 MHz single-cell gun and the 1.3 GHz two-cell buncher cavity. These cavities were designed and built by LBNL based on their experience with similar ones for their Advanced Photo-Injector Experiment (APEX) program. With the 258 nm laser system and Cs2Te cathodes, bunches of up to 300 pC are expected at rates as high as 1 MHz. The paper presents results from this program including the vacuum levels achieved, RF processing and field control experience, dark current measurements and laser and beam characterization.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP026  
About • paper received ※ 26 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP027 Cryogenics Performance of the Vertical Cryostat for Qualifying ESS-SRF High Beta Cavities 895
 
  • S.M. Pattalwar, R.K. Buckley, P.C. Hornickel, K.J. Middleman, M.D. Pendleton, P. Pizzol, P.A. Smith, T.M. Weston, A.E. Wheelhouse, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.J. May, A. Oates, J.T.G. Wilson
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  An innovative vertical cryostat has been developed and commissioned at STFC Daresbury Laboratory for qualifying the high-beta SRF cavities for the ESS (European Spallation Source). The cryostat is designed to test 3 dressed cavities in horizontal configuration in one cold run at 2K. The cavities are cooled to 2K with superfluid liquid helium filled into individual helium jackets of the cavities. This reduces the liquid helium consumption by more than 70% in comparison with the conventional vertical tests. The paper describes the cryogenic system and its performance with detail discussions on the initial results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP027  
About • paper received ※ 22 June 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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THP028 Superconducting RF Modules of TARLA 900
 
  • Ç. Kaya, Ö. Karslı, İ.B. Koç
    Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
  • A. Aksoy, Ö.F. Elçim
    Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
 
  The Turkish Accelerator and Radiation Laboratory (TARLA) is proposed as an accelerator-based radiation source facility to provide a research instrument for researchers from both Turkey and region. The facility is located at the Ankara University Institute of Accelerator Technologies and proposed as the first accelerator based research infrastructure in Turkey. The superconducting accelerator of TARLA is currently under commissioning and will drive two Free Electron Laser (FEL) lines in the mid- and far-infrared ranges and a high flux Bremsstrahlung radiation to 40 MeV electron beam in Continuous Wave (CW) mode. The SRF cryomodules have been delivered by industry in 2017. In this paper, we present the achieved vertical test results of the SRF cavities, the results of the high power RF test of the fundamental power couplers and the first test results of the integrated piezo tuner. After the successful commissioning of the cryogenic plant operating at 1.8 K with ±0.2 mbar pressure stability, the commissioning of the SRF cryomodules is now ongoing and the current status and results achieved so far are explained.  
poster icon Poster THP028 [1.996 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP028  
About • paper received ※ 28 June 2019       paper accepted ※ 02 July 2019       issue date ※ 14 August 2019  
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THP029 Towards Real-time Data Processing using FPGA Technology for High-speed Data Acquisition System at MHz Repetition Rates 905
 
  • M. Bawatna, A. Arnold, J.-C. Deinert, B.W. Green, S. Kovalev
    HZDR, Dresden, Germany
 
  Accelerator-based light sources, in particular, those based on linear accelerators, are intrinsically less stable than lasers or other more conventional light sources because of their large scale. In order to achieve optimal data quality, the properties of each light pulse need to be detected and implemented into the analysis of each experiment. Such schemes are of particular advantage in 4th generation light sources based on superconducting radiofrequency (SRF) technology, since here the combination of pulse-resolved detection schemes with high-repetition-rate is particularly fruitful. Implementation of several different purpose-built CMOS linear array detector will enable to perform arrival-time measurements at MHz repetition rates. An architecture based on FPGA technology will allow an online analysis of the measured data at MHz repetition rate and will decrease the amount of data throughput and disk capacity for storing the data by orders of magnitude. In this contribution, we will outline how the pulse-resolved data acquisition scheme of the TELBE user facility shall be upgraded to allow operation at MHz repetition rates and sub-femtosecond timing precision.  
poster icon Poster THP029 [1.616 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP029  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP031 Operation Experience with the LHC ACS RF System 911
 
  • K. Turaj, L. Arnaudon, P. Baudrenghien, O. Brunner, A.C. Butterworth, F. Gerigk, M. Karppinen, P. Maesen, E. Montesinos, F. Peauger, G.J. Rosaz, E.N. Shaposhnikova, D. Smekens, M. Taborelli, M. Therasse, H. Timko, D. Valuch, N. Valverde Alonso, W. Venturini Delsolaro
    CERN, Meyrin, Switzerland
 
  The LHC accelerating RF system consists of two cryomodules per beam, each containing four single-cell niobium sputtered 400.8 MHz superconducting cavities working at 4.5 K and an average accelerating voltage of 2 MV. The paper summarises the experience, availability and evolution of the system within 10 years of operation. The lessons learned from the successful replacement and re-commissioning of one cryomodule with a spare module, and the recent re-test of the originally installed module on the test stand are also included. Finally, a review of currently launched spare cavity production and long-term developments are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP031  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP032 SRF Gun and SRF Linac Driven THz at ELBE Successfully in User Operation 915
 
  • R. Xiang, A. Arnold, P.E. Evtushenko, S. Kovalev, U. Lehnert, P.N. Lu, S. Ma, P. Michel, P. Murcek, A.A. Ryzhov, J. Schaber, Ch. Schneider, J. Teichert
    HZDR, Dresden, Germany
  • H. Vennekate
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • I. Will
    MBI, Berlin, Germany
 
  Funding: The work was partly supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and Deutsche Forschungsgemeinschaft (DFG) project (XI 106/2-1).
The first all-SRF accelerator driven THz source has been operated as a user facility since 2018 at ELBE radiation center. The CW electron beam is extracted from SRF gun II, accelerated to relativistic energies and compressed to sub-ps length in the ELBE SRF linac with a chicane. THz pulses are produced by pass-ing the short electron bunches through a diffraction radiator (CDR) and an undulator. The coherent THz power increases quadratically with bunch charge. The pulse energy up to 10 µJ at 0.3 THz with 100 kHz has been generated.
 
poster icon Poster THP032 [1.207 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP032  
About • paper received ※ 02 July 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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THP033 Cryogenic Systems Studies for the MINERVA 100 MeV Proton SC LINAC Project 918
 
  • O. Kochebina, F. Dieudegard, T. Junquera
    Accelerators and Cryogenic Systems, Orsay, France
  • D. Vandeplassche
    SCK•CEN, Mol, Belgium
 
  The construction of the first phase of the MYRRHA project (MINERVA: 100 MeV-4 mA proton Linac) was recently decided by the Belgium Government. In the long term, the MYRRHA project plans to construct an ADS demonstrator for the transmutation of long-lived radioactive waste. It will include a subcritical reactor of 100 MW thermal power and a CW proton Linac accelerator (600 MeV-4 mA). The main challenge of this Linac is an extremely high reliability performance to limit stresses and long restart procedures of the reactor. The MINERVA Linac includes 30 cryomodules housing 60 Single-Spoke SC cavities. A cryomodule prototype with its valve box is under construction at IPNO institute. The cavities operate at 352 MHz in a superfluid Helium bath at 2K. Therefore, a reliable SC Linac Cryogenic System is essential. This article presents the preliminary studies in this subject including the analysis of high thermal loads induced by the CW mode operation of cavities (950 W@2 K per cryomodule). A Cryogenic Refrigerator with an equivalent power capacity of 2645 W @4.5 K (3970 W with 1.5 overcapacity factor) is proposed. The constrains for the He distribution in the Linac tunnel are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP033  
About • paper received ※ 23 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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THP034 The First Tests on Vertical Cryostat GERSEMI at FREIA Facility 921
 
  • J.P. Thermeau
    Laboratoire APC, Paris, France
  • K.J. Gajewski, L. Hermansson, R.J.M.Y. Ruber, R. Santiago Kern
    Uppsala University, Uppsala, Sweden
  • T. Junquera, O. Kochebina
    Accelerators and Cryogenic Systems, Orsay, France
 
  A new vertical cryostat, called Gersemi, installed at FREIA Laboratory at Uppsala University, Sweden, is designed to test superconducting magnets and radio-frequency cavities and operates at temperatures between 1.8 K and 4.2 K. Two different inserts can be used to test different superconducting equipment: a helium saturated bath insert for cavities without a helium vessel and a λ-plate insert for magnet testing in superfluid helium pressurized bath. The cold vessel cryostat has an internal diameter of 1.1 m and a useful height of 3.5 m. A valve box supplies the cryostat with the cryogens (LN2, LHe, SHe) and is linked to a gas reheater. The last one is connected to a helium recovery circuit and to a helium pumping system (4.5 g/s at 16 mbar). The Gersemi vertical cryostat is a part of FREIA cryogenic facility which also contains a helium liquefier and a horizontal cryostat inside of a bunker allowing the test of superconducting cavity cryomodules. The first results of the cryogenic tests on this equipment are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP034  
About • paper received ※ 23 June 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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