Keyword: impedance
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MOPP010 Design and Properties of a New DCCT Chamber for the PF-Ring at KEK simulation, operation, HOM, cavity 90
 
  • R. Takai, T. Honda, T. Nogami, T. Obina, Y. Tanimoto
    KEK, Ibaraki, Japan
 
  A DC current transformer (DCCT) for the PF-ring was renewed during the 2018 summer shutdown. A vacuum chamber for the new DCCT was designed based on a circular duct with an inner diameter of 100 mm and has a structure housing a toroidal core inside of electromagnetic shields. The geometry of the ceramic break for interrupting the wall current flow was optimized using a three-dimensional electromagnetic field simulator, and the break was fabricated considering some technical limitations. Both ends of the ceramic break were short-circuited in a high-frequency manner by a sheet-like capacitive structure to suppress the radiation of unneeded higher-order modes (HOMs) into the core housing. The ceramic break is also equipped with water-cooling pipes on metal sleeves brazed to the both ends to efficiently remove the heat generated by HOMs. The new DCCT chamber has been used already in user operation without any problems. A temperature rise near the ceramic break is still approximately six degrees Celsius, even when a 50-mA isolated bunch is stored.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP010  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP020 Development of a Gated IPM System for J-PARC MR electron, detector, operation, GUI 338
 
  • K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  In the Main Ring (MR) of Japan Proton Accelerator Research Complex (J-PARC), a residual-gas ionization profile monitor (IPM) is used to measure bunched beam profiles. After injection, the beam widths of the first ~20 bunched beams are analysed to correct the Quadruple oscillation. While only a few dozen profiles are required for this correction, the present IPM auto-matically measures all bunched beams, more than 2·106 bunches from injection to the extraction, because the present IPM operates using DC. This system is unde-sirable due to the limited lifetime of the Micro Channel Plate (MCP) detector; the more particles the MCP senses, the more it loses gain flatness and thus lifetime. To improve this situation, a gated IPM system has been developed, in which the High Voltage (HV) is operated in pulse mode. Results of performance analysis of a new HV power supply, improvement of the electrodes, and particle-tracking simulation considering the space-charge-electric field of the bunched beam are de-scribed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP020  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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TUPP021 Development of 16 Electrodes Beam-size Monitors for J-PARC MR emittance, quadrupole, proton, operation 342
 
  • M. Tajima, T. Nakaya
    Kyoto University, Kyoto, Japan
  • T. Koseki, T. Toyama
    KEK, Tokai, Ibaraki, Japan
 
  For J-PARC, 16 electrodes beam-monitors are developed. It is possible to measure the transverse moments of beams from the induced voltages. A beam size is calculated from these in two locations with different values of beta functions. Beam-monitors such as a Flying Wire Monitor and an Ionization Profile Monitor (IPM) are already installed. However, the two monitors have issues in measuring higher intensity beams. The former is that the wire gets easily burned out and the latter is that there is a sign of the saturation by a space charge effect. Therefore, these aim at measuring the sizes of high intensity proton beams up to 4.2·10+13 protons/bunch, which corresponds to 1.3 MW in 1.16 s cycle operation of the MR. Furthermore, with high accuracy measurements, the injection mismatch from the RCS is to be decreased. In the beam test in February 2019, the signal-noise ratio (SNR) of this monitor in bunch-by-bunch measurements was nearly 40 dB and lower than the SNR > 50 dB which is comparable to IPM. To improve the SNR, we developed new LPFs for anti-aliasing and improved signal processing. In addition, the second monitor will be installed in August 2019 and tested with beams in November.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP021  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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WEPP003 A new button-type beam position monitor for BESSY II and BESSY VSR vacuum, operation, storage-ring, synchrotron 500
 
  • J.G. Hwang, V. Dürr, F. Falkenstern, M. Ries, A. Schälicke, G. Schiwietz, D. Wolk
    HZB, Berlin, Germany
 
  Funding: This work was supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
The future BESSY VSR system involves more than one order-of-magnitude differences in the total charge of adjacent short and long bunches within the bunch train. Thus, any signal ringing beyond a nanosecond in time will cause a misreading of beam position and current, specifically for low bunch charges. This calls for improved performance for the bunch-selective operation of the beam-position-monitor (BPM) system. We report on the corresponding design and fabrication of a new button BPM with advanced features, such as impedance matching inside the button as well as optimization of insulator material, button size, and position, for reduced crosstalk between buttons.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP003  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP004 Concept of a Beam Diagnostics System for the Multi-Turn ERL Operation at the S-DALINAC cavity, linac, operation, recirculation 505
 
  • M. Dutine, M. Arnold, T. Bahlo, R. Grewe, L.E. Jürgensen, N. Pietralla, F. Schließmann, M. Steinhorst
    TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by BMBF through grant No. 05H18RDRB2 and DFG through GRK 2128.
The S-DALINAC* is a thrice-recirculating linear electron accelerator operating in cw-mode at a frequency of 3 GHz. A path-length adjustment system in the second recirculation beam line allows to shift the beam phase by 360° and thus to operate in ERL mode. For the multi-turn ERL operation, the beam will be accelerated twice and subsequently decelerated twice again (not demonstrated yet). For this mode, it is necessary to develop a nondestructive beam diagnostics system in order to measure the beam position, phase and beam current of both, the accelerated and the decelerated beam, simultaneously in the same beamline. A particular challenge will be the operation at low beam currents of 100 nA, which corresponds to bunch charges of about 30 aC. The conceptional study of a 6 GHz resonant cavity beam position monitor will be presented together with alternative solutions.
* N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP004  
About • paper received ※ 03 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP007 Calibration for Beam Energy Position Monitor System for Riken Superconducting Acceleration Cavity network, linac, cyclotron, synchrotron 519
 
  • T. Watanabe, M. Fujimaki, N. Fukunishi, H. Imao, O. Kamigaito, N. Sakamoto, Y. Watanabe, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  • K. Hanamura, T. Kawachi
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • A. Kamoshida
    National Instruments Japan Corporation, MInato-ku, Tokyo, Japan
  • R. Koyama
    SHI Accelerator Service Ltd., Tokyo, Japan
  • A. Miura
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Miyao, T. Toyama
    KEK, Ibaraki, Japan
 
  Upgrades for the RIKEN Heavy-ion Linac (RILAC) involving a new Superconducting Linac (SRILAC) are currently underway to promote super-heavy element searches and Radio Isotope (RI) production (211At) for medical use at the RIKEN radioactive isotope beam factory (RIBF). If destructive monitors are used, since they generate outgassing, it becomes difficult to maintain the Q value and surface resistance indicating the performance of the superconducting radio frequency (SRF) cavities over a long period of time. Therefore it is crucially important to develop nondestructive beam measurement diagnostics. We have developed a beam energy position monitor (BEPM) system which can measure not only the beam position but also the beam energy simultaneously by measuring the time of flight of the beam. By using parabolic cut, ideal linear response of the quadrupole moments is realized, keeping a good linear position sensitivity at the same time. We fabricated 11 BEPMs and the position calibration system employing a wire method has been used to obtain the sensitivity and offset of BEPMs. We will describe details concerning the BEPM, calibration system and measured results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP007  
About • paper received ※ 05 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP014 A Report on Developments of the BCM and BPM Pickups of the ESS MEBT MEBT, pick-up, quadrupole, vacuum 532
 
  • S. Varnasseri, I. Bustinduy, A. Conde, J. Martin, A. Ortega, I. Rueda, A. Zugazaga
    ESS Bilbao, Zamudio, Spain
  • R.A. Baron, H. Hassanzadegan, T.J. Shea
    ESS, Lund, Sweden
 
  In the framework of the Spanish In-Kind Contribution (IKC) to the construction of the European Spallation Source (ESS-ERIC), ESS-Bilbao is in charge of providing some key systems for the accelerator. In this paper, design and pre-delivery measurements of non-interceptive devices of MEBT (e.g Beam Position Monitor pick-ups, shielded ACCT and FCT) are reported. Overall there are 8 BPMs distributed in MEBT, which 7 of them are used for the beam position and phase measurements and one BPM is used for the fast timing characterization. The latter is used mainly to characterize the partially chopped bunches and rise/fall time of the Beam Chopper. Furthermore there are two ACCTs, one just attached to the beam dump and the other at the last raft of the MEBT. One FCT combined with the second ACCT gives the complementary information on the fast timing characteristics of the beam pulses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP014  
About • paper received ※ 02 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP022 A Method of Correcting the Beam Transverse Offset for the Cavity Bunch Length Monitor cavity, simulation, dipole, laser 565
 
  • Q. Wang, Q. Luo, B.G. Sun
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181)
Cavity bunch length monitor uses monopole modes excited by bunches within the cavities to measure the bunch longitudinal root mean square (rms) length. It can provide a very high accuracy and high resolution. However, when the bunch passes through the cavities with transverse offset (that is, the bunch moves off the cavity axis), the amplitude of the monopole modes will change and cannot reflect the bunch length precisely. In this paper, a method of correcting the beam transverse offset is proposed. Simulation results show that the method can reduce the error of the bunch length measurement significantly.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP022  
About • paper received ※ 03 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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