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Sakai, Hiroshi*; Umemori, Kensei*; Sakanaka, Shogo*; Takahashi, Takeshi*; Furuya, Takaaki*; Shinoe, Kenji*; Ishii, Atsushi*; Nakamura, Norio*; Sawamura, Masaru
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.866 - 868, 2010/03
We started to develop an input coupler for a 1.3 GHz ERL superconducting cavity. Required input power is about 20 kW for the cavity acceleration field of 20 MV/m and the beam current of 100 mA in energy recovery operation. The input coupler is designed based on the STF-BL input coupler and some modifications are applied to the design for the CW 20 kW power operation. We fabricated input coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a 30 kW IOT power source and a test stand constructed for the high-power test. In this report, we mainly describe the results of the high-power test of ceramic window and bellows.
Kondo, Yasuhiro; Hasegawa, Kazuo; Morishita, Takatoshi; Naito, Fujio*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1038 - 1040, 2010/03
Now, J-PARC accelerator developing new RFQ for stable operation. The specification of this new RFQ is same as the now operating RFQ. Resonant frequency is 324MHz, injection energy is 50keV, extraction energy is 3MeV, RF duty is 3%. However, we adopt Dipole Stabilizing Rods (DSR's) instead of Pi-mode Stabilizing Loops (PISL's), which are potential cause of discharging. And assemble method will be brazing to increase reliability. As for the RF couplers, to simplify the structure, we will change to one-feed from two-feed. Maximum peak power to feed is 400kW and duty is 3%. In this paper, the design of the RF coupler for the new J-PARC RFQ is described.
Miura, Akihiko; Sato, Susumu; Sako, Hiroyuki; Yoshikawa, Hiroshi; Hasegawa, Kazuo; Igarashi, Zenei*; Ikegami, Masanori*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.733 - 735, 2010/03
no abstracts in English
Sako, Hiroyuki; Ikegami, Masanori*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.217 - 219, 2010/03
The highest beam loss in the J-PARC linac was observed at the first bending magnet in L3BT in the opposite side to H
deflection. A loss source candidate is H
ionized in LEBT. An H peak was measured with a wire scanner monitor at MEBT1 by splitting H and H with steering magnets. H is separated from H beam with a horizontal steering magnet and a bending magnet at MEBT1 then H is stopped by the scraper originally for beam chopping. The loss and radiations were reduced significantly while good chopping performance is kept.
Suzuki, Hiroyuki; Kobayashi, Tetsuya; Hirano, Koichiro; Naito, Fujio*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1074 - 1076, 2010/03
no abstracts in English
Kashiwagi, Hirotsugu; Miyawaki, Nobumasa; Okumura, Susumu; Ishibori, Ikuo; Kurashima, Satoshi; Yuri, Yosuke; Ishizaka, Tomohisa; Yuyama, Takahiro; Yoshida, Kenichi; Agematsu, Takashi; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.244 - 246, 2010/03
It is necessary to match a beam emittance to an acceptance to minimize a beam loss in an accelerator. In JAEA Takasaki, an emittance and acceptance measurement device is being developed to evaluate the emittance matching to the acceptance. The method of acceptance measurement is as follows. A beam which occupies a small area in phase-space is injected into an accelerator. A detector after the accelerator determines whether the beam pass through the accelerator. The area in phase-space in which the detected beam occupies at the injection is a part of the acceptance. To measure whole acceptance the measurement is done by varying the position of the small area in phase-space. The device to collimate the area in transverse phase-space in the injected beam was developed. It is consisted of two pair of position slit and angle slit so that arbitrary area in two dimensional or four dimensional phase-space could be injected into the accelerator.
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.
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.
ion sourceNamekawa, Yuya; Ueno, Akira; Okoshi, Kiyonori; Oguri, Hidetomo; Ikegami, Kiyoshi*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.845 - 847, 2010/03
The J-PARC H ion source succeeds in producing a beam current of 38 mA without seeding Cs. It satisfies the requirement of the J-PARC 1st stage in which a beam power will be 0.6 MW. However a beam current of more than 60 mA is necessary for the J-PARC 2nd stage in which a beam power will be 1 MW. Therefore, two R&D(research and development)'s are being carried out in order to increase the beam current. One is without seeding Cs and the other is with seeding Cs. In the latter R&D, a beam current of 70 mA is produced with a W-filament and an arc-power of 15 kW. The low arc-power, will be helpful for reducing the Cs consumption rate. The lower Cs consumption rate is necessary for the stabler operation against sparking in high voltage gaps. The practicability of the ion source with seeding Cs is examined by optimizing the filament material and shape, the Cs seeding system including the temperature control of each part of plasma chamber and the plasma confinement magnetic field.
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
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
Kabumoto, Hiroshi; Takeuchi, Suehiro; Ishizaki, Nobuhiro; Yoshida, Takahiro*; Ishiguro, Takayuki*; Yamaguchi, Kazushi*
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1120 - 1122, 2010/03
The JAEA-Tokai tandem accelerator was built for basic science researches with heavy ions. Its superconducting booster was completed in 1994 for increasing the acceleration energy of ions. The booster consists of 40 superconducting acceleration resonators and 10 cryostats. Every resonator is a coaxial quarter wave resonator (QWR) of which frequency is 129.8MHz, and optimum beam velocity is 10% of the light velocity. When it was built, the acceleration field gradients of superconducting resonators were 5.0MV/m at RF power input of 4W on their average. The performance decrease little by little, and it become 4.0MV/m now. Some of the resonators generate X-rays from a low electric field. A field emission will be occurred from small contaminations accumulated on the surfaces of niobium. We examined the high pressure water jet rinsing (HPWR) to re-recondition the superconducting booster. The HPWR is the technology of removing small contaminations on resonator surfaces, and very effective for the improvement of acceleration field gradients. The acceleration field gradients of 20 on-line resonators were improved from 4.4MV to 5.7MV on their average.
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
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.
Hajima, Ryoichi; Nishimori, Nobuyuki
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.137 - 139, 2010/03
X-ray Free-Electron Laser Oscillator (XFEL-O) has been proposed to produce hard X-ray radiation having spatial and temporal coherence. The X-FELO consists of a pair of Bragg mirror of high-reflectivity and focusing elements such as compound refractive lenses or grazing-incidence ellipsoidal mirrors. Electron beams required for driving the X-FELO must have repetition rate matching to the oscillator length, 
1 MHz, and emittance as small as the diffraction limit of the X-ray. Energy-Recovery Linac (ERL) is a suitable device to satisfy the above requirement. In this paper, principle and light source performance of the X-FELO are presented.
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.
Sato, Susumu; Miura, Akihiko; Igarashi, Zenei*; Ikegami, Masanori*; Ueno, Akira; Sako, Hiroyuki; Morishita, Takatoshi; Yoshikawa, Hiroshi; Hasegawa, Kazuo; Kobayashi, Tetsuya
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.298 - 300, 2010/03
no abstracts in English
