| Paper |
Title |
Page |
| MOPAN045 |
Longitudinal Particle Tracking of J-PARC RCS for Synchronization
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260 |
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- M. Yamamoto, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
KEK, Ibaraki
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We have performed particle tracking simulation of J-PARC RCS to study the synchronization process. A frequency offset is added to the nominal RF frequency pattern to shift the center of the bunch, under the condition of the offset value should be 'adiabatic' with respect to the synchrotron motion. Since the synchrotron frequency of the J-PARC RCS is substantially changed during acceleration, the particle tracking simulation helps to decide upper limit of the frequency offset which can be employed.
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| TUPAN056 |
Fabrication Status of ACS Accelerating Modules of J-PARC Linac
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1514 |
| |
- H. Ao, K. Hirano, T. Morishita, A. Ueno
JAEA/LINAC, Ibaraki-ken
- K. Hasegawa
JAEA, Ibaraki-ken
- M. Ikegami
KEK, Ibaraki
- V. V. Paramonov
RAS/INR, Moscow
- Y. Yamazaki
KEK/JAEA, Ibaraki-Ken
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An ACS (Annular Coupled Structure) cavity has been developed for the J-PARC Linac from 190-MeV to 400-MeV. We fabricated a buncher module with two 5-cell accelerating tanks and one 5-cell bridge tank as the first module. The buncher module is shorter than accelerating module that consists of two 17-cell accelerating tanks and one 9-cell bridge tank. The first buncher module achieved the stable operation of 50 Hz, 600 us, 600 kW in the high-power test, which corresponds to the E0 value of 4.8 MV/m. The second buncher module and three accelerating modules are under fabrication continuously. These results of the frequency tuning and assembling are presented in detail.
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| TUPAN059 |
The Precise Survey and the Alignment Results of the J-PARC Linac
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1520 |
| |
- T. Morishita, H. Asano, M. Ikegami
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- K. Hasegawa
JAEA, Ibaraki-ken
- A. Ueno
JAEA/LINAC, Ibaraki-ken
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J-PARC linear accelerator components have been installed and the beam commissioning has been started in Nov. 2006. A total length is more than 400 m including the beam transport line to the 3GeV RCS(Rapid Cycling Synchrotron). Precise alignment of the accelerator components is essential for high quality beam acceleration. After the completion of the linac building, floor elevation was surveyed periodically for more than one year to adjust the beam height from the ion source to the RCS. Before the beam commissioning, a metrological survey has been done. The reference points on the tunnel wall were set up to form a survey network to reduce the survey error less than 1mm in the entire linac. Based on the survey results, the linac components were re-aligned finely to satisfy the requirement. In this paper, the results of the floor elevation and the final alignment are described.
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| TUPAN060 |
The DTL/SDTL Alignment of the J-PARC Linac
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1523 |
| |
- T. Morishita, H. Asano, M. Ikegami, T. Ito
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- K. Hasegawa
JAEA, Ibaraki-ken
- F. Naito, E. Takasaki, H. Tanaka, K. Yoshino
KEK, Ibaraki
- A. Ueno
JAEA/LINAC, Ibaraki-ken
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J-PARC linear accelerator components have been installed and the beam commissioning has been started in Nov. 2006. The length of the linear section is about 300 m which consists of the ion source, the radio frequency quadropole linac(RFQ), the drift tube linac(DTL), separated type DTL(SDTL), and the beam transport line. Precise alignment of the accelerator components is essential for high quality beam acceleration. The required alignment error in the J-PARC linac is 0.1mm in transverse direction. In the DTL/SDTL section, the fine alignment was carried out by using an optical alignment telescope along with the cavity installation. The relay targets were placed at short intervals for smooth connection between neighboring components. After the installation, the DTL/SDTL positions were confirmed by measuring the reference base by using a laser tracker. In this paper, the alignment procedure for the DTL/SDTL section and the results by the laser tracker measurements are described.
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| THYAB02 |
Commissioning of the J-PARC Linac
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2619 |
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- K. Hasegawa
JAEA, Ibaraki-ken
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The J-PARC (Japan Proton Accelerator Research Complex?is a joint project between the Japan Atomic Energy Agency (JAEA) and the High Energy Accelerator Research Organization (KEK) to construct and operate the high-intensity proton accelerator facility. The J-PARC comprises a 400 MeV linac, a 3 GeV rapid-cycling synchrotron (RCS), a 50 GeV main ring synchrotron (MR) and experimental facilities. The energy of the linac is reduced to 181 MeV for the time being, and it will be increased to 400 MeV in the near future. The 3 MeV RFQ, which is a front end of the linac, has been beam commissioned since November 2006, and we will continue to work on the rest of the linac such as a 50 MeV DTL and a 181 MeV Separated-type DTL. The results and status of the J-PARC linac beam commissioning will be presented.
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Slides
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| TUPAN055 |
Present Status of J-PARC Ring RF Ring RF Systems
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1511 |
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- M. Yoshii, S. Anami, E. Ezura, K. Hara, Y. Hashimoto, C. Ohmori, A. Takagi, M. Toda
KEK, Ibaraki
- K. Haga, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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The RCS high frequency accelerating systems are prepared for beam commissioning in September 2007. Installations of cavities, power supplies and amplifiers have been carried out. The systems have been checked for operation and interoperability. For the MR high frequency accelerating system, the examination of the whole system and its final adjustment are done aiming at installation in October 2007. Here, we report on various issues which had been found and solved during the examination and installation period.
masahito.yoshii@kek.jp
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| TUPAN063 |
High Power Test of MA Cavity for J-PARC RCS
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1532 |
| |
- M. Yamamoto, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
KEK, Ibaraki
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We have been testing the RF cavities for the J-PARC RCS, we can operate the cavities without sever problems. Before some MA cores were damaged, then we found such cores have low ribbon resistance. After that we have tested the cavities loaded with improved ribbon resistance.
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| WEPMN038 |
Development of the Beam Chopper Timing System for Multi-Turn Injection to the J-PARC RCS
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2125 |
| |
- F. Tamura
JAEA/LINAC, Ibaraki-ken
- S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
KEK, Ibaraki
- K. Hasegawa, M. Nomura, A. Schnase, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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Multi-turn injection using charge exchange is employed for the J-PARC Rapid Cycling Synchrotron (RCS). To improve the bunching factor of the beam in the ring, the momentum offset injection scheme is used. In each turn, the bunch trains from the linac are injected into the RF buckets with a momentum offset. The bunch train is called the "intermediate pulse". The intermediate pulses are generated in the low energy section of the linac by the RF chopper and pre-chopper. Since the pulse must be synchronized to the RF voltage in the ring, the timing signals for the choppers are generated by the low-level RF (LLRF) system of the RCS and the signals are sent to the chopper control. The RF chopper and the pre-choppers require different pulse widths. Thanks to the direct digital synthesis (DDS) in the LLRF system, precise zero-cross signals for the reference of the chopper pulses are generated without difficulties. The cable route from the RCS LLRF system to the linac chopper control system is more than one kilometer. Thus, the chopper pulses are sent via optical cables. We developed the chopper timing module. We describe the details of the hardware and the preliminary test results.
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| TUPAN043 |
RF Amplitude and Phase Tuning of J-PARC DTL
|
1481 |
| |
- M. Ikegami, Z. Igarashi, H. Tanaka
KEK, Ibaraki
- H. Asano, T. Kobayashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- K. Hasegawa, T. Ito, T. Morishita, S. Sato, A. Ueno
JAEA/LINAC, Ibaraki-ken
- H. Sako
JAEA, Ibaraki-ken
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The beam commissioning of J-PARC linac has been started in November 2006. In the beam commissioning, the tuning of the RF phase and amplitude for its DTL (Drift Tube Linac) has been performed with a phase-scan method. Detailed results of the RF tuning are presented with a brief discription of the tuning procedure.
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| WEPMN040 |
MA Cavities for J-PARC with Controlled Q-value by External Inductor
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2131 |
| |
- A. Schnase, M. Nomura, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
- S. Anami, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
KEK, Ibaraki
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The original J-PARC RCS cavity design* used cut-cores to control the Q-value. Adjusting the distance between the C-shaped core parts the optimum Q=2 is reached. Because of problems related to the cut-core surfaces, the "hybrid cavity" was introduced, using tanks with uncut cores (Q=0.6) in parallel to tanks with cut cores with a wider gap (Q=4), resulting in total Q=2. This was successfully tested. The manufacturing procedure for cut-cores involves more steps than for uncut cores. To reduce risks for long-term operation, the RCS cavities will be loaded with uncut cores for day-1 operation. With uncut cores (Q=0.6) the maximum beam power is limited. Therefore we introduce a parallel inductor, placed in the push-pull tube amplifier driving the cavity, to adjust the Q-value to 2. Parallel vacuum capacitors shift the resonance near to 1.7 MHz. Each of the 10 cavity systems for RCS, necessary for day-1 operation, is tested for at least 300 hours to detect initial problems before installation into the RCS tunnel. We report the results of cavity performance tests with external inductor, which simulate 25Hz operation and the optimization of the combined system of cavity and amplifier.
* C. Ohmori at. al, "High Field-Gradient Cavity for J-PARC 3 GeV RCS", PAC 2004
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| THPAN043 |
Comparison of Trajectory Between Modeling and Experiment for J-PARC Linac
|
3324 |
| |
- T. Ohkawa, K. Hasegawa
JAEA, Ibaraki-ken
- H. Ao, A. Ueno
JAEA/LINAC, Ibaraki-ken
- M. Ikegami
KEK, Ibaraki
- H. Sako
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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In the beam commissioning of J-PARC (Japan Proton Accelerator Research Complex) linac, three simulations codes are used to model the accelerator. We have compared with the experimental results obtained in the beam commissioning to date, where a basic agreement has been confirmed between the modeling and the actual beam behavior.
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