Author: Matsumoto, H.
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WEPOTK023 Simulation Study of Fast Extraction in the Absence of One Septum Magnet for J-Parc Main Ring 2100
 
  • S. Iwata, S. Igarashi, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Sato, T. Shibata, T. Sugimoto, T.Y. Yasui
    KEK, Tokai, Ibaraki, Japan
 
  At J-PARC main ring (MR), the two fast extracting beamlines to the neutrino facility and to the abort dump have a symmetrical layout of 6 septum magnets each, a total of 12. Since there are many magnets, it is necessary to be careful about failure. It is important to consider how to continue beam supply even if one of the septum mag-nets is missing. From July 2021, upgrade works of the FX septum magnets commenced with an aim of increasing the beam power of MR to 1.3 MW from 500 kW. We simulated the beam extraction without one of the septum magnets under the conditions of the new geometry of septum magnets and the new aperture. We found that the beam can be extracted by increasing the current of the surrounding septum magnets and compensating for the output.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK023  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 25 June 2022
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WEPOTK024 Upgrade of Septum Magnets for Fast Extraction in J-Parc Main Ring 2103
 
  • S. Iwata, K. Ishii, H. Matsumoto, N. Matsumoto, Y. Sato, T. Shibata, T. Sugimoto, M. Uota
    KEK, Ibaraki, Japan
 
  We aim to supply a high-power proton beam of 1.3 MW to the neutrino facility from J-PARC Main Ring (MR) by shortening the repetition cycle to 1.16 s from 2.48 s and increasing the number of particles by 30%. The six sep-tum magnets for fast extraction (FX) need to be replaced to reduce the heat that is generated as a result of shorten-ing the repetition cycle. The replacement of the septum magnets began in July 2021 and was completed at the end of May 2022. The beam commissioning starts in June 2022. We report the details of the replacement work and operation test of the new septum magnets. We found a defect in the magnetic coil of the septum (SM32) in August 2021. We decided to postpone its installation to around August 2022 and produce new magnet coils for the SM32. The beam extraction in June 2022 will be per-formed using a temporary vacuum duct instead of the SM32 magnet, and the extraction beam orbit will be maintained by increasing the magnetic field of the other five septum magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK024  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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THOYSP2 The New Eddy Current Type Septum Magnet for Upgrading of Fast Extraction in Main Ring of J-PARC 2428
 
  • T. Shibata, K. Ishii, S. Iwata, H. Matsumoto, T. Sugimoto
    KEK, Ibaraki, Japan
  • K. Fan
    HUST, Wuhan, People’s Republic of China
 
  For our first goal of the beam power of Main Ring for Fast eXtraction (FX), 750 kW, we have been evaluating a new Low-Field FX Septum magnets which are induced eddy current type (Eddy-Septum) since 2014. The pending technical issues are disagreement in two current monitor systems and the long switching time of the Main-charger to Sub-charger at low charging voltage. We measured a gap field during measurement of current, and found no drift in time variation of gap field. Our conclusion was that the cause of the disagreement is electric and radiative noise which make the drift in the time variation. The long-term stability of the output pulsed current depends on the switching time and charging voltage. We investigated the correlation between the keeping time of flat-top charging voltage and long-time stability with various charging voltages. In June 2021, we have first conducted the 1 Hz operation and high-voltage test of the Eddy-Septum which is mounted in a vacuum chamber, and we found no problem. A new pure iron duct type magnetic shield for reducing the leakage field were produced in July 2021. The new LF FX-Septum will be installed in MR in early of 2022.  
slides icon Slides THOYSP2 [5.375 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THOYSP2  
About • Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 21 June 2022
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THPOTK004 The Reduction of the Leakage Field of the Injection Septum Magnet in Main Ring of J-PARC 2774
 
  • T. Shibata, K. Ishii, H. Matsumoto, N. Matsumoto, T. Sugimoto
    KEK, Ibaraki, Japan
 
  A new injection septum magnet (InjSep) was installed in MR in 2016 for one of the upgrading of beam power of MR. We have measured the leakage field before installation, and it was found from the measurement results that the leakage field at the beam upstream region of the circulating duct was enough smaller than previous InjSep, however we tried to reduce the leakage field further by installation a new magnetic shield. First magnetic shield was produced in 2017, and we installed it in the InjSep. The leakage field was reduced, however the magnetic field of a quadrupole magnet at beam upstream of the InjSep was also reduced slightly. The decrease of the magnetic field of the one of main magnet was not permitted from the requirement of beam optics. In consequently, the first version was failed. The second one was produced in 2018, and we measured the leakage field was measured in Jan. 2019. The leakage field was reduced, while no reduction of the quadrupole magnet. We decided to use the second version for beam operation. The new additional shield was started to use in Nov. 2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK004  
About • Received ※ 20 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 13 June 2022
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THPOTK005 The New High Field Septum Magnet for Upgrading of Fast Extraction in Main Ring of J-PARC 2778
 
  • T. Shibata, K. Ishii, S. Iwata, H. Matsumoto, N. Matsumoto, T. Sugimoto
    KEK, Ibaraki, Japan
  • K. Fan
    HUST, Wuhan, People’s Republic of China
 
  Upgrading the beam-power of the J-PARC Main Ring to 750 kW is underway by reducing the cycle from 2.48 s to 1.3 s. Required upgrade of the four High Field (HF) Septa will be completed in 2022. The operation test of a new HF SM31 was conducted in 2020. First was 1 Hz operation test. The power supply had no problem in the operation, and the joule heating at the magnet coil was lower than limit. We found a good linearity between the current and the gap field which has no saturation. The field integral in the magnet gap was measured to calculate the appropriate current for beam operation, and we found it was 3,400 A. We compared the gap field of the neutrino side with that of the beam abort side. The magnitude of gap field had no significant discrepancy larger than its measurement accuracy. The end-fringe field was measured and the we found large leakage field still existed around the end-fringes. We are producing an additional magnetic shield which will be mounted in the circulating beam duct, and it will finished in Feb. 2022. In next March we will install the inner shield and measured the leakage field. After that we will install the new SM31 in MR.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK005  
About • Received ※ 20 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 28 June 2022
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