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Shimada, Taihei; Yamamoto, Masanobu; Suzuki, Hiromitsu; Toda, Makoto*; Hasegawa, Katsushi*; Omori, Chihiro*; Tamura, Fumihiko; Schnase, A.; Hara, Keigo*; Nomura, Masahiro; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1080 - 1082, 2010/03
Few magnetic alloys cores of the RF cavities which are installed in the 3 GeV rapid cycling synchrotron of the J-PARC have buckled after the operation of about two years. We heated cores in the air and measured thermal deformation in order to get information about the buckling process. We report the results.
Kojima, Toshiyuki; Takahashi, Hiroki; Sakaki, Hironao; Maebara, Sunao
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.487 - 489, 2010/03
no abstracts in English
Nishimori, Nobuyuki; Nagai, Ryoji; Iijima, Hokuto; Hajima, Ryoichi; Yamamoto, Masahiro*; Muto, Toshiya*; Miyajima, Tsukasa*; Honda, Yosuke*; Kuriki, Masao*; Kuwahara, Makoto*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.872 - 874, 2010/03
no abstracts in English
ion sourceIkegami, Kiyoshi*; Ueno, Akira; Oguri, Hidetomo; Namekawa, Yuya; Okoshi, Kiyonori
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.839 - 841, 2010/03
A cesium-free H ion source driven with a LaB
filament is under operation at the Japan Proton Accelerator Research Complex (J-PARC). The ion source succeeded in producing the maximum beam current of 38 mA, which is satisfied with the requirement for the J-PARC initial stage of 36 mA. The operating beam current, however, is within 30-33 mA during the accelerator beam commissioning run because we restrict the maximum arc current to 300 A for a highly stable beam operation. In order to improve the arc power efficiency for the beam current and to examine the possibility to satisfy with the requirement for the J-PARC final goal, we started to survey about the optimal size and shape of the LaB filament by using the H ion source test stand. All the tests were carried out with the same condition such as the arc current (300A), the beam energy and the magnet configuration of the plasma chamber. The beam current of 35.2 mA was extracted using a double spiral LaB filament with a diameter of 29.5 mm and length of 35.5 mm, which is the same dimension as the present J-PARC ion source. By using a smaller one with a diameter of 15 mm and length of 34 mm, the beam current was increased to 41.8 mA. Furthermore, it was increased to 43.4 mA by using a flat triple hairpin shape LaB filament.
Okumura, Susumu; Miyawaki, Nobumasa; Yuyama, Takahiro; Ishizaka, Tomohisa; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Ishibori, Ikuo; Yuri, Yosuke; Nara, Takayuki; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.572 - 574, 2010/03
High-frequency change of beams accelerated for users is required at the JAEA AVF cyclotron, since the irradiation time is short in most cases and a large variety of beams is used. The ratio of the beam changing time to the whole operation time is not negligible and the offering machine time for users is half the required one. We are developing a technique for reducing the changing time of the magnetic field of the cyclotron, which dominates the beam changing time. Since a precise and stable magnetic field is required for acceleration in the cyclotron, especially for advanced beam applications, such as microbeam production, a magnetic field measurement system with a nuclear magnetic resonance (NMR) magnetometer was developed to monitor a wide range of magnetic field for acceleration of variety of beams in the JAEA AVF cyclotron.
Matsuda, Makoto; Asozu, Takuhiro; Kutsukake, Kenichi; Nakanoya, Takamitsu; Hanashima, Susumu; Takeuchi, Suehiro
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.827 - 829, 2010/03
no abstracts in English
Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Nomura, Masahiro; Schnase, A.; Toda, Makoto*; Suzuki, Hiromitsu; Shimada, Taihei; Hara, Keigo*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.366 - 368, 2010/03
For stable acceleration of the high intensity proton beams, increasing the bunching factor by the longitudinal painting is essentially important to reduce the space-charge tune shift. The momentum offset injection method and applying the second harmonic RF are employed for the longitudinal painting in the J-PARC RCS. We employ wide band magnetic alloy (MA) cavities to realize the dual-harmonic operation, in which each cavity is driven by the superposition of the fundamental and the second harmonic RF signals. By the dual-harmonic operation we can generate the large amplitude second harmonic RF without extra cavities for the second harmonic. We report the beam test results of the longitudinal painting.
Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki; Iijima, Hokuto; Muto, Toshiya*; Honda, Yosuke*; Miyajima, Tsukasa*; Yamamoto, Masahiro*; Kuriki, Masao*; Kuwahara, Makoto*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.863 - 865, 2010/03
A 500-kV, 10-mA photocathode DC gun has been designed and is now under fabrication by the collaboration efforts of JAEA, KEK, Hiroshima University and Nagoya University. We have adopted a multiple-stacked cylindrical ceramic insulator, because this type of ceramic insulator has shown good stability and robustness at the 250-kV JAEA FEL gun and the 200-kV Nagoya polarized gun. The Cockcroft-Walton voltage multiplier, the ceramic insulator, the vacuum chambers has been fabricated and a high-voltage test will be successfully achieved soon. Up-to-date status of the gun development is presented in detail.
Shinto, Katsuhiro; Vermare, C.*; Asahara, Hiroo; Sugimoto, Masayoshi; Garin, P.*; Maebara, Sunao; Takahashi, Hiroki; Sakaki, Hironao; Kojima, Toshiyuki; Ohira, Shigeru; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.668 - 670, 2010/03
Progress of the IFMIF/EVEDA prototype accelerator in fiscal year of 2008 is described. All the sub-systems of the prototype accelerator have started to design, settled the plan of the manufacturing and component tests and fixed the design parameters. As a result of the analysis of planning for the engineering validation of the IFMIF accelerator system, the project duration to be prolonged to the end of 2014 including some months for contingency was approved by the BA Steering Committee. In this article, the design status of each accelerator component, the interface between the accelerator components and the IFMIF/EVEDA Accelerator Building settled in International Fusion Energy Research Centre (IFERC) in Rokkasho and the proposed accelerator commissioning plan for the engineering validation will be presented.
ion sourceOguri, Hidetomo; Ueno, Akira; Ikegami, Kiyoshi*; Namekawa, Yuya; Okoshi, Kiyonori
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.842 - 844, 2010/03
A cesium-free H ion source driven with a LaB filament is being operated for J-PARC. The beam commissioning of J-PARC accelerators started in November 2006. As of June 2009, there have been 25 beam commissioning or supply runs. In these runs, the ion source has been successfully operated in two different modes. One is a low beam current mode, in which approximately 5 mA is produced. The other is a high beam current mode, in which approximately 30 mA is produced. According to the task of the run, one of the two modes was selected. Since the beam current can be maintained within a few percent errors by tuning the ion source parameter once a day, 24 hours beam operation with an ion source operator only in day time was started in April 2008. The total interruption time during the runs due to the ion source failure is approximately 50 hours as of June 2009. The availability of the ion source is calculated to be 99%. The interruptions were mainly caused by the insufficient lifetime of the filament. By a few modifications on the filament shape administered until August 2007, we succeeded in achieving the lifetime of 2,030 hours, which included 1,250 hours in the low beam current mode and 780 hours in the high beam current mode.
Takahashi, Hiroki; Kojima, Toshiyuki; Sakaki, Hironao; Maebara, Sunao
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.490 - 492, 2010/03
no abstracts in English
Iijima, Hokuto; Nagai, Ryoji; Nishimori, Nobuyuki; Hajima, Ryoichi
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.897 - 899, 2010/03
no abstracts in English
Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito*; Omori, Chihiro*; Hayashi, Naoki; Kawase, Masato; Watanabe, Kazuhiko*; Yoshikawa, Muneyoshi*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.737 - 740, 2010/03
The longitudinal phase space tomography, which was evolved to retrieve the two-dimensional beam distribution in the longitudinal phase space with computer tomography algorithms, is very useful diagnostic tool in the accelerator domain. The simple reconstruction tool was developed for the J-PARC RCS and MR with the convolution back projection method for the beam storage mode. On the assumption that the longitudinal profiles should not be disturbed for one period of the synchrotron oscillation, such two-dimensional profiles can be reconstructed easily from one-dimensional bunch beam profiles, which are measured for every turn by the wall current monitor.
Miyawaki, Nobumasa; Okumura, Susumu; Kurashima, Satoshi; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Yuri, Yosuke; Yuyama, Takahiro; Ishizaka, Tomohisa; Ishibori, Ikuo; Nara, Takayuki; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.183 - 185, 2010/03
The characteristics of beam phase (BP) for three of acceleration harmonic modes (H=1, 2, 3) were investigated in the central region of the JAEA AVF cyclotron. Experiments were made to clarify relations of BP to the spatial displacements of ion beam orbits in the radial direction at the phase defining slit (PDS), and also to the initial condition of BP at the exit of the inflector defined by the phase shift of the beam bunching (BB). Some correlation of the BPs to both of the position of PDS and the phase shift of BB were observed in the case of H=1, but no correlation was found in the case of H=2. And in the case of H=3, only correlations of the intensity of the beam phase to them were observed with larger phase width than that in case of H=2. It is expected that optimization of the injection system and the central region of the cyclotron can be made according to these characteristics of BP depending on H, so as to obtain higher transmission of high quality ion beams.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1047 - 1049, 2010/03
The beam commissioning of J-PARC linac has been started since November 2006. After the scheduled shutdown in summer 2007, the beam is successfully delivered from the linac to the RCS. Since then, a stable beam provision was emphasized. However, the trip in the RFQ was increased at the end of Sept. 2008, then, the stability of the beam operation decreased. To improve this situation, we started to prepare a new RFQ cavity as a backup machine. The basic concept of the engineering design is the simplicity and the effective vacuum pumping aiming at the stable operation. A 3m long cavity is divided into 3 modules longitudinally. A numerical control machining with ball-end mill is chosen for a vane machining. Four vanes are vacuum brazed each other after machining. Each modules are aligned on the platform using a linear motion guide. A basic design of the key components on machining and brazing are described in this proceeding.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Matsumoto, Hiroshi*; Hori, Yoichiro*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1050 - 1052, 2010/03
The beam commissioning of J-PARC linac has been started since November 2006. After the scheduled shutdown in summer 2007, the beam is successfully delivered from the linac to the RCS. Since then, a stable beam provision to RCS was emphasized. However, the trip in the RFQ was increased at the end of Sept. 2008, then, the stability of the beam operation decreased. To improve this situation, we started to prepare a new RFQ cavity as a backup machine. The RF simulation is underway for the design of this backup RFQ. A basic estimation on the key components on RF properties such as a tuner, a dipole stabilizer, and a local field correction at the vacuum port are described in this proceeding.
Hasegawa, Kazuo; Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Kobayashi, Tetsuya; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Kawamata, Hiroshi*; Hori, Yoichiro*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.693 - 695, 2010/03
The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a beam from the ion source to the DTL. The beam test of the linac was started in November 2006 and 181 MeV beam was successfully accelerated in January 2007. Since then, the linac has been delivered beams for commissioning of the linac itself, downstream accelerators and facilities. Trip rates of the RFQ, however, suddenly increased in Autumn 2008, and we are suffering from this issue for user run operation. We tried to recover by tender conditioning, modification of RF control, improvement of vacuum and so on. We manage to have beam operation. In this report, we describe the status of the RFQ.
Sawamura, Masaru; Umemori, Kensei*; Furuya, Takaaki*; Sakai, Hiroshi*; Shinoe, Kenji*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.878 - 880, 2010/03
HOM absorbers are one of the key components to determine the ERL cavity performance to reduce the HOM problem for the high current operation. When a beam line HOM damper is installed inside the cryomodule, the HOM damper is cooled down to liquid nitrogen temperature. The RF absorber used for the HOM damper is required to have good frequency and temperature properties. Some ferrites and ceramics are tested for permittivity and permeability of frequency-dependence and temperature-dependence measured with a GM refrigerator from room temperature to 40 K. The HOM damper is designed by optimizing the parameters such as length, thickness and position with microwave simulation codes. Test models of the HOM damper are being designed and fabricated to test the RF, mechanical, cooling and temperature properties.
Kobayashi, Tetsuya; Anami, Shozo*; Michizono, Shinichiro*; Fang, Z.*; Suzuki, Hiroyuki; Yamaguchi, Seiya*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1065 - 1067, 2010/03
In the J-PARC Linac LLRF, for the cavity start-up, the cavity resonance is automatically controlled to be the accelerating frequency (324 MHz and 972 MHz) with a mechanical tuner installed on the cavity. Figure 1: FPGA block diagram of the digital FB and FF control system for the J-PARC linac LLRF. We are planning to introduce a new method of the cavity-input frequency matching into the digital LLRF control system instead of the tuner control for the cavity start-up. In order to match the frequency with the detuned cavity, the output RF frequency is modulated by way of phase rotation with the I/Q modulator, while the cavity tuner is fixed. The detuning of the cavity is obtained from phase gradient of the cavity field decay at the RF-pulse end and the phase rotation is automatically controlled by a FPGA and a DSP. No hardware modification is necessary for this frequency modulation method.
Kobayashi, Tetsuya; Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Suzuki, Hiroyuki; Yamaguchi, Seiya*; Okada, Yoshihito*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1068 - 1070, 2010/03
A 972-MHz RF system is being developed for 400-MeV upgrade of the J-PARC linac. The accelerating field stabilities should be less than 
1% in amplitude and 1
in phase. The basic digital LLRF (Low-Level RF) concept is the same as that of the present 324-MHz system with a compact-PCI crate. The main alterations are RF and clock generator (RF&CLK), mixer and I/Q modulator (IQ&Mixer) and digital LLRF algorithm. Since the typical decay time of the new system is faster (because its operational frequency is higher than that of the present 324-MHz cavity), chopped beam compensation is essential. The performance study of the digital feedback system with a cavity simulator is summarized.
