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Ishikado, Motoyuki*; Takahashi, Ryuta*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ishimaru, Sora*; Yamauchi, Sara*; Kawamura, Seiko; Kira, Hiroshi*; Sakaguchi, Yoshifumi*; Watanabe, Masao; et al.
JPS Conference Proceedings (Internet), 41, p.011010_1 - 011010_7, 2024/05
Watanabe, Masao; Kihara, Takumi*; Nojiri, Hiroyuki*
Quantum Beam Science (Internet), 7(1), p.1_1 - 1_10, 2023/03
A pulsed magnet system has been developed as a new user-friendly sample environment equipment at the Materials and Life Science Experimental Facility in Japan Proton Accelerator Research Complex. It comprises a vacuum chamber, a 4 K closed-cycle refrigerator for samples, and a nitrogen bath made of a stainless-steel tube with a miniature solenoidal coil. The coil is cooled by liquid nitrogen supplied by an automatic liquid nitrogen supply system, and the sample is cooled by a refrigerator. This combination facilitates the automatic high magnetic field diffraction measurement for the user's operation. A relatively large scattering angle is up to 42 degrees, which is significantly wider than the previous setup. Neutron diffraction experiments were performed on a multiferroic TbMnO
and the field dependence of the diffraction peaks was clearly observed. The new pulsed magnet system was established for a practical high magnetic field diffraction for the user program.
Watanabe, Masao; Nojiri, Hiroyuki*
Journal of Neutron Research, 21(1-2), p.39 - 45, 2019/05
Magnetic field acts directly on the spin and the orbital motion of electron in the material and interesting quantum phenomena and phase transition are found in high magnetic field. Recently, experimental equipments using neutron beams in high magnetic field have been rapidly developed. For example, superconducting DC magnet up to 17 T has developed for neutron scattering experiments. Although the sample environment team in the MLF have several DC superconducting magnets up to 7 T as a sample environment apparatus, some users have requested the preparation of higher field magnets. However, another magnet technology is needed to generate higher than 20 T. However, it is difficult to construct such a large system in the MLF from the point of view of construction space. It is practical to employ a pulsed magnetic field as it enables operation of smaller energy as well as downsizing of the instruments. Therefore, we have been developed a compact and movable pulsed magnet system up to 30 T.
Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.
Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05
The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading 
He cryostat, a bottom-loading 
He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.
Kawamura, Seiko; Hattori, Takanori; Harjo, S.; Ikeda, Kazutaka*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki; Watanabe, Masao; Sakaguchi, Yoshifumi*; Oku, Takayuki
Neutron News, 30(1), p.11 - 13, 2019/05
In Japanese neutron scattering facilities, some SE equipment that are frequently used at an instrument, such as the closed-cycle refrigerator (CCR), have been prepared for the instrument as standard SE. They are operated for user experiments by the instrument group. The advantage of this practice is that they can optimize the design of the SE for the instrument and can directly respond to users' requests. On the other hand, the SE team in the Materials and Life Science Experimental Facility (MLF) in J-PARC has managed commonly used SE to allow neutron experiments with more advanced SE. In this report, recent SE in the MLF is introduced. Highlighted are the SE in BL11, BL19, BL21 and BL17 and other SE recently progressed by the SE team.
Watanabe, Masao; Nojiri, Hiroyuki*; Ito, Shinichi*; Kawamura, Seiko; Kihara, Takumi*; Masuda, Takatsugu*; Sahara, Takuro*; Soda, Minoru*; Takahashi, Ryuta
JPS Conference Proceedings (Internet), 25, p.011024_1 - 011024_5, 2019/03
Recently, neutron scattering experiments have been rapidly progressed under high magnetic field. In the J-PARC, proto-type compact pulse magnet system with the power supply, the coil and the sample stick has been developed. Basic specifications of the power supply are as follows; maximum charged voltage with capacitor is 2 kV, maximum current is 8 kA, repetition rate is a pulse per several minutes and pulse duration is several msec. Maximum magnetic field in the coil is more than 30 Tesla. The sample stick is designed for Orange-Cryostat. In this presentation, We report the details of the pulsed magnet system and the performance of it on neutron scattering experiments at MLF beam line (HRC).
Kawamura, Seiko; Oku, Takayuki; Watanabe, Masao; Takahashi, Ryuta; Munakata, Koji*; Takata, Shinichi; Sakaguchi, Yoshifumi*; Ishikado, Motoyuki*; Ouchi, Keiichi*; Hattori, Takanori; et al.
Journal of Neutron Research, 19(1-2), p.15 - 22, 2017/11
Sample environment (SE) team at the Materials and Life Science Experimental Facility (MLF) in J-PARC has worked on development and operation of SE equipment and devices. All the members belong to one sub-team at least, such as Cryogenic and magnet, High temperature, High pressure, Soft matter and special environment including Pulse magnet, Hydrogen environment, Light irradiation and He spin filter. Cryostats, a magnet, furnaces, a VX-6-type Paris-Edinburgh press and a prototype of a Spin-Exchange Optical Pumping (SEOP) based He spin filter for polarized neutron beam experiments are in operation. Furthermore, a prototype of compact power supply for a pulsed magnet system is currently developed. In the J-PARC Research Building, several pieces of equipment for softmatter research such as a rheometer and a gas and vapor adsorption measurement instrument have been prepared.
Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.
Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09
Neutron devices such as neutron detectors, optical devices including supermirror devices and 
He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.
Suganuma, Kazuaki; Togashi, Tomohito; Watanabe, Masao; Kinsho, Michikazu
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.678 - 680, 2014/07
Technical issues of the kicker magnet system in the J-PARC 3GeV RCS are presented based on the operating experience during four years. For the high voltage cables, many scratches on the polyethylene surface were observed at the edge parts, the surfaces were reinforced by a semi-conductive layer with high-dielectric materials. For all matching resisters, the values have been increased due to deterioration with age, and the counter measure is under reviewing. For Thyratron tubes, a stable operation was established, and the beam stop rate by false operation was drastically reduced from 13% to less than 0.5%.
Hayashi, Naoki; Harada, Hiroyuki; Horino, Koki; Hotchi, Hideaki; Kamiya, Junichiro; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; et al.
Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3833 - 3835, 2014/07
no abstracts in English
Shobuda, Yoshihiro; Irie, Yoshiro*; Toyama, Takeshi*; Kamiya, Junichiro; Watanabe, Masao
Nuclear Instruments and Methods in Physics Research A, 713, p.52 - 70, 2013/06
Times Cited Count：8 Percentile：53.52(Instruments & Instrumentation)Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro; Kinsho, Michikazu
Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.471 - 473, 2012/08
The 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) uses 8 pulse kicker magnets for the beam extraction at a repetition rate of 25 Hz. Each kicker power supply has 2 thyratrons and thus they are 16 in total. An average life time of thyratrons even more than the J-PARC annual operation time of 5000 hours and a stable operation with a downtime of less than only 0.5% has already been achieved. The present maintenance procedures and statistics for the long term operation with thyratrons are reported in this paper.
Hayashi, Naoki; Harada, Hiroyuki; Hotchi, Hideaki; Kamiya, Junichiro; Saha, P. K.; Shobuda, Yoshihiro; Takayanagi, Tomohiro; Tani, Norio; Yamamoto, Kazami; Yamamoto, Masanobu; et al.
Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3921 - 3923, 2012/05
The injection energy upgrade from 181 to 400 MeV for J-PARC RCS is planned in 2013. One power supply was replaced and using for a normal operation. An IGBT chopper type power supply which has larger switching noise will be changed to a capacitor bank type. New injection system allows the center injection with 400 MeV and switching painting area. As further steps for the leakage field, it begins to diminish the effect from the beam transport line. A quadrupole corrector system is designed and fabricated to compensate the beta beat due to the injection bump as the first step. Two profile monitors will be modified to correct position systematic errors and third one is going to be installed at dispersion free section. It is important to minimize kicker impedance lower, which may cause the beam instability. A diode, which has high reverse breakdown voltage and works with lower forward voltage, has been developed. Using this new diode, an experiment shows the impedance becomes lower.
Watanabe, Masao; Hayashi, Naoki; Shobuda, Yoshihiro; Suganuma, Kazuaki; Takayanagi, Tomohiro; Togashi, Tomohito; Toyama, Takeshi*
Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.3629 - 3631, 2012/05
Stable operation is required for RCS at J-PARC. In the kicker system at extraction section of RCS, there had been many troubles for unstable operation of the thyratrons switches of the power supply just after 25 pps operation started in February 2009. However, the operation was improved by handling thyratrons in appropriate manner in October 2010. After the grate earthquake on 11 March 2011, injection and extraction magnets, power supplies, cables and bus-duct were checked. The results of the measurements and the checks were all not in the problem. We have to reach extraction beam power of 1 MW in RCS in the near future. Kicker impedance is most severe among other impedance sources. The matching resistor and newly developed diodes are connected at the power supply to reduce the impedance. We confirmed that reduced voltages and stable operation of accelerator.
Togashi, Tomohito; Watanabe, Masao; Suganuma, Kazuaki; Takayanagi, Tomohiro; Ueno, Tomoaki; Tani, Norio; Watanabe, Yasuhiro
Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.579 - 583, 2010/08
The 3-GeV RCS (Rapid Cycling Synchrotron) at J-PARC (Japan Proton Accelerator Research Complex) has the pulse kicker power supply system which uses the thyratron switches for beam extraction. There were many troubles caused by unstable operation of thyratrons after beam commissioning started in January 2009. The, failure rate of the kicker power supply system was about 13%. To improve this status, we have been managed the operations of the thyratron in detail. As a result, the unstable operation has been improved and the failure rate has been achievement less than 0.5% (Run33) in April, 2010. In this paper, we report current status of the thyratron operation of the kicker power supply system.
Takayanagi, Tomohiro; Yoshimoto, Masahiro; Watanabe, Masao; Saha, P. K.; Ueno, Tomoaki; Togashi, Tomohito; Yamazaki, Yoshio; Kinsho, Michikazu; Fujimori, Hiroshi*; Irie, Yoshiro*
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3293 - 3295, 2010/05
It has been designed the pulse bending magnet for switching the painting area to the MLF and MR, which is located in injection line area in J-PARC 3-GeV RCS. After upgrading the linac energy to 400 MeV, the two pulse magnets switch the injection beam orbit to change the each painting area by each shot of 25 Hz. The magnetic field strength switching by 25 Hz are required for the painting injection. Furthermore, in the case of the beam commissioning of the 3-GeV RCS, the center injection is performed. Therefore, the wide range of the beam bending angle from 3 mrad to 38 mrad is required for the pulse magnets.
Watanabe, Masao; Kamiya, Junichiro; Suganuma, Kazuaki; Takayanagi, Tomohiro; Tani, Norio; Togashi, Tomohito; Ueno, Tomoaki; Watanabe, Yasuhiro
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.3296 - 3298, 2010/05
3 GeV rapid cycling synchrotron of J-PARC accelerates proton beams from the 181 MeV up to 3 GeV. Proton beams in the RCS are fast extracted by kicker magnets at the repetition rate of 25 Hz. The rise time of the magnetic field is approximately 260 ns due to the propagation time through the coaxial cable and the kicker magnet itself. The flat top length of it is required to 840 ns in order to extract two beam bunches. Pulse forming lines (PFL) and thyratrons are used to make the rise time and the flat top, at the maximum charging voltage of 80 kV. 16 thyratrons are used in the eight power supplies of the kicker system. Since thyratrons are gaseous discharge switching devices, they often make misfire or self-breakdown in several hours. In this paper, present status of operation and voltage adjustment method of the reservoir and cathode heater power supply of the thyratrons in the kicker system are described.
Shobuda, Yoshihiro; Toyama, Takeshi*; Kamiya, Junichiro; Watanabe, Masao
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2024 - 2026, 2010/05
There was the famous formula of the horizontal impedance for the matched-traveling wave kicker. However, the real and the imaginary parts of the impedance do not satisfy the Hilbert transformations. On the other hand, the impedance measured by a loop method does not directly give the beam impedance. In this paper we theoretically derive the beam impedance and reproduce the impedance by the estimated inductances of the kicker by the measurement.
Suganuma, Kazuaki; Kamiya, Junichiro; Watanabe, Masao; Takayanagi, Tomohiro; Togashi, Tomohito; Ueno, Tomoaki
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.569 - 571, 2010/00
The insulating oil became brownish-red and sticky solid materials emerged at the connectors of the coaxial cable for transmitting high-voltage pulse. Then, maintenance of the system increased extremely. In order to identify the cause, the author analyzed the gas contained in the discolored insulating oil. The cause was considered to be the deterioration of oil at less than 300 
C and the deterioration of oil due to electric discharge. In addition, the connector configuration simulation was conducted. It was found that electric fields tend to concentrate in the air layer at the upper part of connector and at the polyethylene tip of the receiving connector. A structure in which electric fields are alleviated was determined with the simulation, and electricity was applied, and the inner condition was observed. As a result, when the inner diameter of the outer cylinder was increased, oil deterioration was alleviated and dielectric strength voltage was improved.
Kamiya, Junichiro; Takayanagi, Tomohiro; Watanabe, Masao
Physical Review Special Topics; Accelerators and Beams, 12(7), p.072401_1 - 072401_9, 2009/07
Times Cited Count：12 Percentile：61.1(Physics, Nuclear)Kicker magnets in the extraction section of the rapid cycling synchrotron in the J-PARC facility succeeded in extracting the proton beam accelerated up to 3 GeV in the first commissioning with beam. The operation parameters of the kicker system agreed well with the parameters, which were estimated from the magnetic field measurement and the current test of each power supply. The distribution of the integrated magnetic field is flat enough to meet the beam requirements. The beam based measurement of the flattop of the magnetic field was performed with the beam position monitors. Although a ringing structure was observed, which exceeded the specified limit, the degree of the flattop distortion could be corrected by the timing adjustment of the output current. The stability of the power supply is sufficient to achieve stable beam extraction. Dependence of the rise time on the gas pressure was strictly measured and the number of unwanted prefires could be reduced.
