Keyword: resonance
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MOPP007 Versatile Beamline Cryostat for the Cryogenic Current Comparator (CCC) for FAIR cryogenics, operation, simulation, vacuum 77
 
  • D.M. Haider, F. Kurian, M. Schwickert, T. Sieber, T. Stöhlker, F. Ucar
    GSI, Darmstadt, Germany
  • H. De Gersem, N. Marsic, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  • J. Golm
    FSU Jena, Jena, Germany
  • J. Golm, T. Koettig
    CERN, Meyrin, Switzerland
  • M. Schmelz, R. Stolz, V. Zakosarenko
    IPHT, Jena, Germany
  • T. Stöhlker
    IOQ, Jena, Germany
  • T. Stöhlker, V. Tympel
    HIJ, Jena, Germany
  • V. Zakosarenko
    Supracon AG, Jena, Germany
 
  Funding: Work supported by AVA - Accelerators Validating Antimatter the EU H2020 Marie-Curie Action No. 721559 and by the BMBF under contract No. 05P15SJRBA and 5P18SJRB1.
The Cryogenic Current Comparator (CCC) extends the measurement range of traditional non-destructive current monitors used in accelerator beamlines down to a few nano-amperes of direct beam current. This is achieved by a cryogenic environment of liquid helium around the beamline, in which the beam’s magnetic field is measured with a Superconducting Quantum Interference Device (SQUID), which is itself enclosed in a superconducting shielding structure. For this purpose, a versatile UHV-beamline cryostat was designed for the CCCs at FAIR and is currently in production. It is built for long-term autonomous operation with a closed helium re-liquefaction cycle and with good access to all inner components. The design is supported by simulations of the cryostat’s mechanical eigenmodes to minimize the excitation by vibrations in an accelerator environment. A prototype at GSI has demonstrated the self-contained cryogenic operation in combination with a 15 l/day re-liquefier. The cryostat will be used in CRYRING to compare the FAIR-CCC-X with newly developed CCC-types for 150 mm beamlines. Both which will supply a nA current reading during commissioning and for the experiments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP007  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEAO01 Technological Review of Beam Position Button Design and Manufacture FEL, electron, electronics, SRF 445
 
  • A.F.D. Morgan
    DLS, Oxfordshire, United Kingdom
 
  A workshop in May 2019, hosted by DLS (UK), reviewed both the design and the manufacturing aspects of beam position monitor (BPM) pick-up buttons with an integrated UHV feedthrough and coaxial connector. The UHV feedthrough technology (e.g. ceramic brazing vs glass-sealing), the limits on mechanical tolerances, reproducibility and material choices for high reliability were examined by more than 20 diagnostics users of these devices and a number of reputed manufacturers. Calibration techniques and tools and methods for inspection & testing were also assessed. This talk will present the outcome & conclusions of this workshop and identify challenges and opportunities for future BPM manufacture.  
slides icon Slides WEAO01 [1.824 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO01  
About • paper received ※ 05 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEAO02 Pile-Up Effect of Cold Button BPMs in the European XFEL Accelerator cavity, FEL, electron, electronics 450
 
  • D. Lipka, B. Lorbeer
    DESY, Hamburg, Germany
 
  The European XFEL facility is in operation with a maximum of 2700 bunches in one train. The highest bunch repetition rate is 4.5 MHz; this corresponds to a minimum time separation of 222 ns. The measurement of the beam properties for each bunch in a train is required. Therefore the beam position monitor (BPM) system needs to separate the signals from each bunch. All BPM types (button, re-entrant and cavity) fulfill this requirement except a few button BPMs installed inside of the cold accelerator module, where Pile-Up from the train can be observed. To identify the cause of this effect we measured the S-parameters during a shutdown of the accelerator, compared it with a similar BPM at the FLASH accelerator but located in a warm section and finally measured the spectrum of the button signal during beam operation. As a result, resonances were found at about 2.46 GHz with relatively high quality factor that remains within the frequency range accepted by the electronics.  
slides icon Slides WEAO02 [5.621 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEAO02  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WECO03 Tune Computation via Model Fitting to Swept Machine Response Measurement synchrotron, feedback, operation, betatron 482
 
  • M.G. Abbott, G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  At Diamond Light Source we compute the horizontal and vertical tunes by fitting a simple multi-pole resonator model to the measured electron beam frequency response. The transverse (and longitudinal) tune response is measured by sweeping an excitation across the range of possible tune frequencies and synchronously measuring the IQ response. The multi-pole resonator model is a good fit to the measured behaviour, but the fitting process is surprisingly challenging. Problems include noisy measurements, very complex beam responses in the presence of increasing chromaticity, poor data when the beam is close to instability, and a number of challenges with the stability of the algorithm. The tune fitting algorithm now in use at Diamond has been developed and refined over many years. It is finally stable enough to work reliably throughout most beam operating conditions. The algorithm involves alternating peak finding and non-linear fitting, with a fairly naive mathematical approach; the main focus is on providing reliable results.  
slides icon Slides WECO03 [1.059 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO03  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)