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Ha, H.*; Kim, J.*; Gu, G. H.*; Harjo, S.; Gong, W.; Hong, S.-J.*; Kim, H. S.*
Materials Characterization, 234, p.116086_1 - 116086_12, 2026/04
Times Cited Count：2 Percentile：84.58(Materials Science, Multidisciplinary)
neutron diffraction at cryogenic temperaturesYamashita, Takayuki*; Harjo, S.; Gong, W.; Kawasaki, Takuro; Morito, Shigekazu*; Morooka, Satoshi; Fujii, Hidetoshi*; Tomota, Yo*
Journal of Alloys and Compounds, 1056, p.186668_1 - 186668_11, 2026/02
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)
2022)Aso, Tomokazu; Ariyoshi, Gen; Muto, Hideki*; Tanaka, Shigeto*
JAEA-Technology 2025-005, 51 Pages, 2025/10
JAEA-Technology-2025-005.pdf:2.47MB
The cryogenic hydrogen system of the J-PARC center is one of the most important pieces equipment, which is a refrigeration system for moderating (cooling) the high energy neutrons generated the spallation neutron source of the Material and Life Science Experimental Facility (MLF) that is used by many users from Japan and abroad. Since the first operation of the MLF for neutron use in 2008, the cryogenic hydrogen system has been continuously operated and maintained, and related technology development has been carried out. This report summarized these activities over the past five years.
Gu, G. H.*; Jeong, S. G.*; Heo, Y.-U.*; Harjo, S.; Gong, W.; Cho, J.*; Kim, H. S.*; 4 of others*
Journal of Materials Science & Technology, 223, p.308 - 324, 2025/07
Times Cited Count：9 Percentile：88.88(Materials Science, Multidisciplinary)Kim, Y. S.*; Kang, T.*; Hong, S.-K.*; Brechtl, J.*; Lebyodkin, M.*; Cheng, Y.-H.*; Huang, E.-W.*; Liaw, P. K.*; Harjo, S.; Gong, W.; et al.
Acta Materialia, 292, p.120970_1 - 120970_16, 2025/06
Times Cited Count：15 Percentile：96.30(Materials Science, Multidisciplinary)Naeem, M.*; Rehman, A. U.*; Romero Resendiz, L.*; Salamci, E.*; Aydin, H.*; Ansari, P.*; Harjo, S.; Gong, W.; Wang, X.-L.*; 3 of others*
Communications Materials (Internet), 6, p.65_1 - 65_13, 2025/04
Naeem, M.*; Ma, Y.*; Tian, J.*; Kong, H.*; Romero-Resendiz, L.*; Fan, Z.*; Jiang, F.*; Gong, W.; Harjo, S.; Wu, Z.*; et al.
Materials Science & Engineering A, 924, p.147819_1 - 147819_10, 2025/02
Times Cited Count：7 Percentile：86.13(Nanoscience & Nanotechnology) neutron diffractionNaeem, M.*; Ma, Y.*; Knowles, A. J.*; Gong, W.; Harjo, S.; Wang, X.-L.*; Romero Resendiz, L.*; 6 of others*
Materials Science & Engineering A, 916, p.147374_1 - 147374_8, 2024/11
Times Cited Count：5 Percentile：46.67(Nanoscience & Nanotechnology)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
Kim, Y. S.*; Chae, H.*; Lee, D.-Y.*; Han, J. H.*; Hong, S.-K.*; Na, Y. S.*; Harjo, S.; Kawasaki, Takuro; Woo, W.*; Lee, S.-Y.*
Materials Science & Engineering A, 899, p.146453_1 - 146453_7, 2024/05
Times Cited Count：12 Percentile：78.71(Nanoscience & Nanotechnology)Sugano, Michinaka*; Machiya, Shutaro*; Shobu, Takahisa; Shiro, Ayumi*; Kajiwara, Kentaro*; Nakamoto, Tatsushi*
Superconductor Science and Technology, 33(8), p.085003_1 - 085003_10, 2020/08
Times Cited Count：13 Percentile：40.51(Physics, Applied)Aso, Tomokazu; Tatsumoto, Hideki*; Otsu, Kiichi*; Kawakami, Yoshihiko*; Komori, Shinji*; Muto, Hideki*; Takada, Hiroshi
JAEA-Technology 2019-013, 77 Pages, 2019/09
JAEA-Technology-2019-013.pdf:5.59MB
At Materials and Life Science experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), a 1-MW pulsed spallation neutron source is equipped with a cryogenic hydrogen system which circulates liquid hydrogen (20 K and 1.5 MPa) to convert high energy neutrons generated at a mercury target to cold neutrons at three moderators with removing nuclear heat of 3.8 kW deposited there. The cryogenic system includes an accumulator with a bellows structure in order to absorb pressure fluctuations generated by the nuclear heat deposition in the system. Welded inner bellows of the first accumulator was failured during operation, forcing us to improve the accumulator to have sufficient pressure resistance and longer life-time. We have developed elemental technologies for manufacturing welded bellows of the accumulator by a thick plate with high pressure resistance, succeeding to find optimum welding conditions. We fabricated a prototype bellows block and carried out an endurance test by adding a pressure change of 2 MPa repeatedly. As a result, the prototype bellows was successfully in use exceeding the design life of 10,000 times. Since distortions given during welding and assembling affect functionality and lifetime of the bellows, we set the levelness of each element of the bellows as within 0.1
. The improved accumulator has already been in operation for about 25,000 hours as of January 2019, resulting that the number of strokes reached to 16,000. In July 2018, we demonstrated that the accumulator could suppress the pressure fluctuation generated by the 932 kW beam injection as designed. As current operational beam power is 500 kW, the current cryogenic hydrogen system could be applicable for stable operation at higher power in the future.
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.
Aso, Tomokazu; Teshigawara, Makoto; Hasegawa, Shoichi; Muto, Hideki; Aoyagi, Katsuhiro; Nomura, Kazutaka; Takada, Hiroshi
Journal of Physics; Conference Series, 1021(1), p.012085_1 - 012085_4, 2018/06
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Takada, Hiroshi; Haga, Katsuhiro; Teshigawara, Makoto; Aso, Tomokazu; Meigo, Shinichiro; Kogawa, Hiroyuki; Naoe, Takashi; Wakui, Takashi; Oi, Motoki; Harada, Masahide; et al.
Quantum Beam Science (Internet), 1(2), p.8_1 - 8_26, 2017/09
At the Japan Proton Accelerator Research Complex (J-PARC), a pulsed spallation neutron source provides neutrons with high intensity and narrow pulse width to promote researches on a variety of science in the Materials and life science experimental facility. It was designed to be driven by the proton beam with an energy of 3 GeV, a power of 1 MW at a repetition rate of 25 Hz, that is world's highest power level. A mercury target and three types of liquid para-hydrogen moderators are core components of the spallation neutron source. It is still on the way towards the goal to accomplish the operation with a 1 MW proton beam. In this paper, distinctive features of the target-moderator-reflector system of the pulsed spallation neutron source are reviewed.
Bhattacharya, R.*; Vaghela, H.*; Sarkar, B.*; Patel, P.*; Das, J.*; Srinivasa, M.*; Isono, Takaaki; Kawano, Katsumi
IOP Conference Series; Materials Science and Engineering, 171, p.012058_1 - 012058_8, 2017/03
Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Saito, Toru; Koizumi, Norikiyo
IEEE Transactions on Applied Superconductivity, 26(4), p.4204705_1 - 4204705_5, 2016/06
Japan Atomic Energy Agency (JAEA) has responsibility to procure 9 Toroidal Field (TF) coils and 19 TF coil structures for ITER project. A TF coil structure consists of the main body structure having D-shape with 13.6 m of height and 9 m of width in which a superconducting winding pack is enclosed and the components to connect adjacent TF coils or other surrounding components. TF coil structures are manufactured from austenitic stainless steel having high tensile strength and fracture toughness at cryogenic temperature (4K) in order to ensure the huge electromagnetic force. As structural materials, austenitic stainless steel having high Manganese and Nitrogen which was named as JJ1 and high Nitrogen containing 316LN stainless steel are applied. These materials are welded each other by Tungsten Inert Gas (TIG) welding with FMYJJ1, which had been developed for welding material based on JJ1. The cryogenic mechanical properties of welded joints which have over 200 mm of actual thickness are limited due to less demonstration of such a heavy thick joints. In addition, destructive test specimens cannot be taken from actual TF coil structure. Hence, it is necessary to confirm actual thickness of welded joint performance by actual welding conditions mock-up. JAEA manufactured some welded joint mock-ups having the same welding thickness and combination of base materials as actual TF coil structure by applying actual welding conditions. JAEA measured mechanical properties of tensile and fracture toughness in liquid Helium environment by using test specimens taken from these welded joint mock-ups. This study reports these mechanical test results of welded joints at cryogenic temperature. "The view and opinions expressed herein do not necessarily reflect those of the ITER Organization."
Yamanishi, Toshihiko
Purazuma, Kaku Yugo Gakkai-Shi, 92(1), p.21 - 25, 2016/01
In a fusion reactor, the hydrogen isotope separation system is required in the fuel cycle system to supply deuterium (D) and tritium (T) as its fuel. In ITER, 90% of T must be recycled through the isotope separation system. On the other hand; since the hydrogen (H) gas is finally exhausted to the environment, the T concentration in the H gas from the isotope separation system should be as low as reasonable achievable. Hence, the isotope separation system of a fusion reactor must have a large separation factor. The flow rate of the isotope separation system of a fusion reactor reaches to 300 mol/h. Only the cryogenic distillation method can meet the above conditions (large flow rate and separation factor) and is most likely used as a hydrogen separation system in a fusion reactor. In this chapter, several simulation methods and a set of experimental data of the cryogenic distillation columns are described in detail.
Yoshida, Kiyoshi; Natsume, Kyohei; Kizu, Kaname; Koide, Yoshihiko; Michel, F.*; Hoa, C.*; Wanner, M.*
Teion Kogaku, 50(12), p.575 - 582, 2015/12
no abstracts in English
Sn strand at cryogenic temperatureHarjo, S.; Kawasaki, Takuro; Hemmi, Tsutomu; Ito, Takayoshi*; Nakamoto, Tatsushi*; Aizawa, Kazuya
JPS Conference Proceedings (Internet), 8, p.031001_1 - 031001_5, 2015/09
