Author: Oguri, H.
Paper Title Page
MO1P02 Approaches to High Power Operation of J-PARC Accelerator 29
 
  • H. Oguri
    JAEA/J-PARC, Tokai-mura, Japan
 
  Japan Proton Accelerator Research Complex (J-PARC) accelerators have been having over 10 years of operation experience. In 2006, the J-PARC linac started beam operation with an energy of 181 MeV. To realize the nominal performance of 1 MW at 3 GeV Rapid Cycling Synchrotron (RCS) and 0.75 MW at a 30 GeV Main Ring synchrotron (MR), the linac energy was upgrade to 400 MeV by adding an annular-ring coupled structure linac, and the beam current was also upgraded from 30 to 50 mA by replacing a new ion source and an RFQ. After the upgrade, the RCS demonstrated 1MW equivalent beam operation and currently operates 400 kW for the Material and Life Science Facility. The MR beam power is increasing and becomes about 480 kW beam to the Neutrino Facility and about 50 kW at the Hadron Experimental Facility. Further upgrade plan of 1.5 MW beam power from the RCS is now in consideration. To achieve the plan, it is necessary to increase by about 20 % both beam current and pulse length at the linac. The detail process in the past upgrade and the possibility for further upgrade at the linac will be presented in this talk.  
slides icon Slides MO1P02 [5.595 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-MO1P02  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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TUPO079 Numerical and Experimental Study of H Beam Dynamics in J-PARC LEBT 519
TUOP10   use link to see paper's listing under its alternate paper code  
 
  • T. Shibata, K. Ikegami, Y. Liu, K. Ohkoshi, M. Otani
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • A. Miura, H. Oguri, K. Shinto
    JAEA/J-PARC, Tokai-mura, Japan
  • F. Naito, K. Nanmo, A. Takagi
    KEK, Tokai, Ibaraki, Japan
 
  Negative hydrogen ion (H) beam dynamics in J-PARC Low Energy Beam Transport (LEBT) has been investigated by numerical modeling which calculates particle transport with effect of space charge and collision processes. Understandings of H beam transport in LEBT is important for high transmission rate from Ion Source (IS) to Radio Frequency Quadrupole (RFQ) in J-PARC in higher beam current in future. In 2017, 45 mA beam current of H has been extracted from IS in J-PARC user operation which has been increased from 30 mA in last 2 years. The beam current is planned to be increased to 50 mA in the next upgrade. As the beam current increase, IS/LEBT commissioning becomes more difficult because of the higher space charge (SC). Especially in J-PARC, vacuum pressure is around 10-5 Pa by 15 mmf orifice located in the center of LEBT. The orifice prevents residual gas injection from IS to LEBT/RFQ and thus produces stronger SC effect. In the presentation, numerical results are compared with actual results from J-PARC Linac beam commissioning. A comparison of the results shows that location of the 15 mmf orifice results in two peaks of RFQ transmission rate against SOL currents.  
slides icon Slides TUPO079 [0.968 MB]  
poster icon Poster TUPO079 [1.699 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-TUPO079  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO049 Field Tuning of a Radio-frequency Quadrupole Using Full 3D Modeling 798
 
  • T. Morishita, K. Hasegawa, Y. Kondo, H. Oguri
    JAEA/J-PARC, Tokai-mura, Japan
  • M. Otani
    KEK, Ibaraki, Japan
 
  The radio-frequency quadrupole linac (RFQ) is operating in the frontend of the J-PARC linac to accelerates 50 mA negative hydrogen beams from 0.05 MeV to 3 MeV. As a backup, the spare RFQ has been fabricated in 2018. The vane-voltage ramping is adopted to improve the acceleration efficiency so that the cross-sectional shape is adjusted longitudinally to produce the designed voltage distribution. Then, the three-dimensional cavity models including modulations and cutbacks were created in CST Micro-Wave Studio. The vane-base widths and cutback depths were optimized to produce the desired vane-voltage distribution. In the final tuning, the heights of the stub turners were also determined based on the tuner responses obtained from the full 3D models. In this paper, the detailed design process of the cavity dimensions and the result of the low-power measurements are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO049  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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