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Journal Articles

Upgrade of the 3-MeV linac for testing of accelerator components at J-PARC

Kondo, Yasuhiro; Hirano, Koichiro; Ito, Takashi; Kikuzawa, Nobuhiro; Kitamura, Ryo; Morishita, Takatoshi; Oguri, Hidetomo; Okoshi, Kiyonori; Shinozaki, Shinichi; Shinto, Katsuhiro; et al.

Journal of Physics; Conference Series, 1350, p.012077_1 - 012077_7, 2019/12

 Times Cited Count:0 Percentile:100

We have upgraded a 3-MeV linac at J-PARC. The ion source is same as the J-PARC linac's, and the old 30-mA RFQ is replaced by a spare 50-mA RFQ, therefore, the beam energy is 3 MeV and the nominal beam current is 50 mA. The main purpose of this system is to test the spare RFQ, but also used for testing of various components required in order to keep the stable operation of the J-PARC accelerator. The accelerator has been already commissioned, and measurement programs have been started. In this paper, present status of this 3-MeV linac is presented.

Journal Articles

Status of the J-PARC Linac LLRF system

Futatsukawa, Kenta*; Fang, Z.*; Fukui, Yuji*; Shinozaki, Shinichi; Mizobata, Satoshi; Sato, Yoshikatsu*

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.486 - 489, 2017/12

In the J-PARC linac, the LLRF systems consist of twenty-four 324-MHz systems and twenty-five 972-MHz systems for ACS cavities. The 324-MHz LLRF systems, which were installed in the stations of RFQ, DTLs, and SDTLs, have been used since the beginning of the J-PARC and are more than ten years into the development. Realistically speaking, the incensement of the failure frequency for these systems is expected. Additionally, it is difficult to maintain those for some discontinued boards of a digital feedback (DFB) and a digital feedforward (DFF) at cPCI, and the older OS and developing environment of software. Therefore, we are starting to study the new LLRF system of the next generation. In the present, we are exploring several possibilities of a new way and investigating each advantage and disadvantage. The project and the status of the development for the new system in the J-PARC linac LLRF are introduced.

Journal Articles

Behavior of intermolecular interactions in $$alpha$$-glycine under high pressure

Shinozaki, Ayako*; Komatsu, Kazuki*; Kagi, Hiroyuki*; Fujimoto, Chikako*; Machida, Shinichi*; Sano, Asami; Hattori, Takanori

Journal of Chemical Physics, 148(4), p.044507_1 - 044507_8, 2017/01

 Times Cited Count:7 Percentile:30.01(Chemistry, Physical)

Pressure-response on the crystal structure of deuterated $$alpha$$-glycine was investigated at room temperature, using powder and single-crystal X-ray diffraction, and powder neutron diffraction measurements under high pressure. No phase change was observed up to 8.7 GPa, although anisotropy of the lattice compressibility was found. Neutron diffraction measurements indicated the distance of the intermolecular D$$cdots$$O bond along with the $$c$$-axis increase with compression up to 6.4 GPa. The distance of another D$$cdots$$O bond along with the $$a$$-axis decreased with increasing pressure, and became the shortest intermolecular hydrogen bond above 3 GPa. In contrast, the lengths of the bifurcated N-D$$cdots$$O and C-D$$cdots$$O hydrogen bonds, which are formed between the layers of the $$alpha$$-glycine molecules along the $$b$$-axis, decreased significantly with increasing pressure. The decrease of the intermolecular distances resulted in the largest compressibility of the $$b$$-axis, compared to the other two axes. Hirshfeld analysis suggested that the reduction of the void region size, rather than shrinkage of the strong N-D$$cdots$$O hydrogen bonds, occurred with compression.

Journal Articles

Development of beam scrapers using a 3-Mev linac at J-PARC

Hirano, Koichiro; Asano, Hiroyuki; Ishiyama, Tatsuya; Ito, Takashi; Okoshi, Kiyonori; Oguri, Hidetomo; Kondo, Yasuhiro; Kawane, Yusuke; Kikuzawa, Nobuhiro; Sato, Yoshikatsu; et al.

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.310 - 313, 2016/11

We have used a beam scraper with the incident angle of 65deg to reduce the beam power deposition density in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC linac. The 65$$^{circ}$$ scraper was irradiated by the H$$^{-}$$ beam up to particle number of 1.47E22. We observed a lot of surface projections with several hundred micrometers high in the beam irradiation damage on the scraper by using the laser microscope. In order to study the limits of scrapers, we constructed a new 3 MeV linac at J-PARC. We will conduct the scraper irradiation test at the end of this year.

Journal Articles

Development of RF chopper system at J-PARC Linac, 2

Hirano, Koichiro; Kondo, Yasuhiro; Kawane, Yusuke; Shinozaki, Shinichi; Miura, Akihiko; Morishita, Takatoshi; Sawabe, Yuki; Sugimura, Takashi*; Naito, Fujio*; Fang, Z.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.944 - 947, 2015/09

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT1 between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We replaced with a newly fabricated RF chopper to decrease beam loss for the operation with 50 mA. We installed two new scrapers to absorb the higher power of the deflected beam by the RF chopper. This paper describes the RF chopper system and beam irradiation test results of the scraper.

Journal Articles

Crystal structure of magnesium dichloride decahydrate determined by X-ray and neutron diffraction under high pressure

Komatsu, Kazuki*; Shinozaki, Ayako*; Machida, Shinichi*; Matsubayashi, Takuto*; Watanabe, Mao*; Kagi, Hiroyuki*; Sano, Asami; Hattori, Takanori

Acta Crystallographica Section B; Structural Science, Crystal Engineering and Materials (Internet), 71(1), p.74 - 80, 2015/02

 Times Cited Count:11 Percentile:24.79(Chemistry, Multidisciplinary)

Magnesium dichloride decahydrate (MgCl$$_{2}$$10H$$_{2}$$O) and its deuterated counterpart (MgCl$$_{2}$$10D$$_{2}$$O) are identified for the first time by in-situ powder synchrotron X-ray and spallation neutron diffraction. These substances are crystallized from a previously unidentified nanocrystalline compound, which originates from an amorphous state at low temperature. A combination of a recently developed autoindexing procedure and the charge-flipping method reveals that the crystal structure of MgCl 10H$$_{2}$$O consists of an ABCABC... sequence of Mg(H$$_{2}$$O)$$_{6}$$ octahedra. The Cl$$^{-}$$ anions and remaining water molecules unconnected to the Mg$$^{2+}$$ cations bind the octahedra, similar to other water-rich magnesium dichloride hydrates. The D positions in MgCl$$_{2}$$10D$$_{2}$$O, determined by the difference Fourier methods using the neutron powder diffraction patterns at 2.5 GPa, show the features such as bifurcated hydrogen bonds and tetrahedrally coordinated O atoms.

Journal Articles

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.

Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12

 Times Cited Count:5 Percentile:54.22(Physics, Nuclear)

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Journal Articles

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

no abstracts in English

Journal Articles

Development of RF chopper system at J-PARC Linac

Hirano, Koichiro; Ito, Takashi; Kondo, Yasuhiro; Shinozaki, Shinichi; Chishiro, Etsuji; Miura, Akihiko; Morishita, Takatoshi; Ikegami, Masanori*; Kubota, Chikashi*; Sugimura, Takashi*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.858 - 861, 2014/06

Two RF-deflecting cavities as a chopper and a beam scraper have been used in the MEBT between a 324 MHz RFQ and a 50-MeV DTL of the J-PARC Linac. We plan to increase a peak beam current up to 50 mA by replacing an ion source and a RFQ after the summer shutdown in 2014. Beam loss occurs in the RF chopper for the 50 mA operation. Moreover, the beam scraper cannot fully stand the beam load with 50 mA, 0.5 ms, 3 MeV, and 25 Hz. We have studied the new RF chopper cavity by using HFSS code and the tandem scraper system with two scrapers.

Journal Articles

Improvement for the trip rate of klystron high-voltage power supplies in J-PARC linac

Hori, Toshihiko; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; Oguri, Hidetomo; Futatsukawa, Kenta*; Fukui, Yuji*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1001 - 1003, 2014/06

no abstracts in English

Journal Articles

Present status of klystron power supply systems for J-PARC linac 2013

Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Miyajima, Noriyuki*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.605 - 607, 2014/06

This report describes the present status of the klystron power supply systems for the J-PARC linac. The systems for the 181 MeV linac were operated from September to May. A few breakdowns were occurred, and are described in this report. The new systems for the upgrade of the linac from 181MeV to 400 MeV have been installed until now, and the 3 HVDCPSs and the 3 anode modulators of the new systems have been operated. All the systems for 400 MeV linac will be operated in this autumn.

Journal Articles

Upgrade of power supply system for RF-chopper at J-PARC Linac

Futatsukawa, Kenta*; Ikegami, Masanori*; Ito, Yuichi; Kikuzawa, Nobuhiro; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Takahiro*; Chishiro, Etsuji; Hirano, Koichiro; Fang, Z.*; et al.

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1149 - 1153, 2014/06

no abstracts in English

Journal Articles

Upgrade of control signal distribution system at J-PARC Linac

Futatsukawa, Kenta*; Ito, Yuichi; Kikuzawa, Nobuhiro; Kobayashi, Tetsuya*; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Takahiro*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1126 - 1129, 2014/06

no abstracts in English

Journal Articles

Discharge suppression for anode modulator in J-PARC linac

Chishiro, Etsuji; Kawamura, Masato*; Hori, Toshihiko; Sato, Fumiaki; Shinozaki, Shinichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1224 - 1226, 2013/08

no abstracts in English

Journal Articles

High power RF test station for RFQII at J-PARC linac

Hori, Toshihiko; Chishiro, Etsuji; Shinozaki, Shinichi; Sato, Fumiaki; Morishita, Takatoshi; Kondo, Yasuhiro; Futatsukawa, Kenta*; Fukui, Yuji*; Kawamura, Masato*; Sugimura, Takashi*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1240 - 1242, 2013/08

no abstracts in English

Journal Articles

Precise measurement of the installed cable attenuation

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Sato, Fumiaki; Shinozaki, Shinichi

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.765 - 768, 2013/08

no abstracts in English

Journal Articles

Status of J-PARC linac LLRF after the Tohoku Earthquake

Futatsukawa, Kenta*; Anami, Shozo*; Kobayashi, Tetsuya*; Fang, Z.*; Fukui, Yuji*; Michizono, Shinichiro*; Kawamura, Masato*; Sato, Fumiaki; Shinozaki, Shinichi; Chishiro, Etsuji; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.769 - 773, 2013/08

no abstracts in English

Journal Articles

RF control system for the RFQ test station at J-PARC linac

Fukui, Yuji*; Kawamura, Masato*; Kobayashi, Tetsuya*; Fang, Z.*; Futatsukawa, Kenta*; Sato, Fumiaki; Shinozaki, Shinichi; Suzuki, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.762 - 764, 2013/08

no abstracts in English

Journal Articles

Present status of klystron power supply systems for J-PARC linac 2012; Recovery from Earthquake Disaster, HVDCPS breakdown and energy upgrade

Kawamura, Masato*; Chishiro, Etsuji; Hori, Toshihiko; Shinozaki, Shinichi; Sato, Fumiaki; Fukui, Yuji*; Futatsukawa, Kenta*; Yamazaki, Masayoshi*; Sagawa, Ryu*; Yukitake, Mitsuteru*; et al.

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1243 - 1247, 2013/08

no abstracts in English

Journal Articles

High-power test and thermal characteristics of a new radio-frequency quadrupole cavity for the Japan Proton Accelerator Research Complex linac

Kondo, Yasuhiro; Morishita, Takatoshi; Hasegawa, Kazuo; Chishiro, Etsuji; Hirano, Koichiro; Hori, Toshihiko; Oguri, Hidetomo; Sato, Fumiaki; Shinozaki, Shinichi; Sugimura, Takashi*; et al.

Physical Review Special Topics; Accelerators and Beams, 16(4), p.040102_1 - 040102_8, 2013/04

 Times Cited Count:11 Percentile:33.22(Physics, Nuclear)

We performed a high-power test of a new radio-frequency quadrupole (RFQ II) for the J-PARC linac. RFQ II was developed as a spare RFQ because the operating J-PARC RFQ has suffered from a sparking problem. First, the conditioning of RFQ II was carried out; after 50 h of conditioning, RFQ II became very stable with a nominal power and duty of 330 kW and 3%, respectively. Next the thermal properties were measured because the resonant frequency of RFQ II is tuned by changing the temperature of the cooling water. The frequency response was measured and compared to finite-element method simulation results, confirming that the simple two-dimensional model reproduces the experimental data well. The differences in the field distribution with changes in the rf loading and the cooling-water temperature were also measured, and no serious field distortion was observed. Therefore, we conclude that RFQ II can perform well as a high-power rf cavity.

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