| Paper | Title | Page |
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| MOPEC066 | Status of Mass Production of the ACS Cavity for the J-PARC Linac Energy Upgrade | 618 |
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The mass production of the ACS (Annular Coupled Structure) cavity started from March 2009 for the J-PARC Linac energy upgrade from 181 MeV to 400 MeV. This upgrade project requires 18 ACS accelerating modules and two debunchers additionally within three years. The construction schedule is so tight that we have to optimize the fabrication process. For example the geometrical beta is varied for each accelerating module, thus the several test cells were fabricated and for the all beta before the mass production to confirm the initial design and the frequency tuning procedure. This paper describes our approach for the mass production and the current status and results. |
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| MOPEC065 | Recent Status and Future Plan of J-PARC MA Loaded RF Systems | 615 |
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The Japan Proton Accelerator Complex includes the 3GeV rapid cycling synchrotron (RCS) and the 50GeV main ring synchrotron (MR). Both synchrotrons use the high field gradient magnetic alloy (MA) loaded cavities. In RCS, 11 RF systems have been fully operational since December 2008. The RCS RF systems are operated with dual-harmonic acceleration voltages. Beam acceleration and bunch shape manipulation are efficiently taking place. 120kW of the neutron user operation was started at the Material and Life science facilities in November 2009. In MR synchrotron, the 5th RF system were installed in August 2009, and therefore 5 RF systems are now in operation. Beam commissioning for delivering protons to the hadron facility and neutrino beam experimental facility are under way. The neutrino user experiment is intended to start January 2010. Proton beam operation with more than 100kW is required. The approaches to realizing high intensity operation and the MR upgrade plan will be presented. |
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| TUPD010 | Simulation of Longitudinal Emittance Control in J-PARC RCS | 1940 |
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The Longitudinal emittance in J-PARC RCS should be controlled to accelerate a high intensity proton beam with minimal beam loss. In order to study and minimize the beam loss during acceleration, the optimized way to add the 2nd higher harmonic rf has been calculated by a particle tracking code. Furthermore, the bunch shape at RCS extraction should be controlled and optimized for the MR injection. For this purpose, the optimum RCS acceleration pattern has been calculated. We describe the simulation results and the comparison with the beam test. |
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| THPEA022 | Condition of MA Cores in the RF Cavities of J-PARC Synchrotrons after Several Years of Operation | 3723 |
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We have been operating the RF cavities loaded with MA cores with a high field gradient of more than 20 kV/m since October 2007. We have been measuring the RF cavity impedance at the shutdown periods, and we detected the impedance reductions of RCS RF cavities on January and June 2009. Taking out the RF cavities from the beam line and opening them, we found that many of cores showed a buckling at the inner radius. Also detachment of the epoxy coating intended to prevent rusting was observed. We report the detail of condition of MA cores and the relation between the impedance reduction and core condition. |