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Koizumi, Norikiyo; Matsui, Kunihiro; Okuno, Kiyoshi
Cryogenics, 50(3), p.129 - 138, 2010/03
Times Cited Count：11 Percentile：42.10(Thermodynamics)Japan Atomic Energy Institute (JAEA), as Japanese Domestic Agency, has responsibility to procure 25% Toroidal Field (TF) coil conductor for ITER. The proto conductor was successfully developed and qualification test of these conductors were performed in the SULTAN test facility in Switzerland. Since the conductor length is only 2.5 m, the current distribution in the conductor is affected by joint. Because the joint is subjected to back ground magnetic field distributed from 2 T to 7 T, joint resistance is not uniform along the cable axis due to electromagnetic resistance of copper in the joint. This causes non-uniform current distribution in the conductor and voltage on surface of jacket is not a constant along circumference direction. It is therefore made difficult to correctly evaluate conductor critical current performance. Thus, the authors developed a simulation model to calculate current distribution in the conductor using a lumped circuit model and voltage distribution on the jacket using a 2-dimensinal steady state potential model. In addition, effect of electromagnetic resistance in the joint is carefully considered by using a model taking account of shape of current path. These simulation results show that the current sharing temperature estimated from the measured voltage is a few hundred milli-Kelvin lower than the one when the current distribution is uniform. In addition, it is figured out that the electromagnetic resistance in the joint originates relatively large non-uniform current distribution. This can be reduced by inserting high resistive thin layer in the joint to decrease the effect of the electromagnetic resistance.
Shindo, Yasuhide*; Takeda, Tomo*; Narita, Fumio*; Miura, Masaya*; Watanabe, Shinya*; Koizumi, Norikiyo; Idesaki, Akira; Okuno, Kiyoshi
Cryogenics, 50(1), p.36 - 42, 2010/01
Times Cited Count：17 Percentile：55.51(Thermodynamics)This paper reports the cryogenic interlaminar shear properties of composite insulation systems for the superconducting magnet coils in the International Thermonuclear Experimental Reactor (ITER). Short beam shear tests were performed at room temperature, liquid nitrogen temperature (77 K) and liquid helium temperature (4 K) on three insulation systems consisting of woven glass fiber reinforced plastic (GFRP) composites with different polymer resins and polyimide films, and the dependence of their apparent interlaminar shear strength on the temperature and the polymer resins was discussed. A detailed observation of failed specimens was made to verify the failure mechanisms. Insulation systems subjected to 
irradiation at room temperature were also considered, and the effect of irradiation on the cryogenic interlaminar shear properties was examined.
Al developmentTakeuchi, Takao*; Kikuchi, Akihiro*; Banno, Nobuya*; Kitaguchi, Hitoshi*; Iijima, Yasuo*; Tagawa, Kohei*; Nakagawa, Kazuhiko*; Tsuchiya, Kiyosumi*; Mitsuda, Shiori*; Koizumi, Norikiyo; et al.
Cryogenics, 48(7-8), p.371 - 380, 2008/07
Times Cited Count：63 Percentile：87.46(Thermodynamics)NbAl has advantages of better tolerance to strain/stress and a higher critical magnetic field (30 T at 4.2 K) for stoichiometric composition over NbSn. The rapid-heating, quenching and transformation annealing (RHQT) process enables to form a stoichiometric NbAl with fine grain structures via metastable bcc supersaturated-solid-solution. As a result a large critical current density of NbAl is achieved over the whole range of magnetic fields without trading off the excellent strain tolerance. A long-length of RHQ processing has been established, and a rectangular but Cu stabilized NbAl strand is about be commercially available for NMR uses. Ag or Cu internal stabilization and Cu ion-plating/electroplating techniques have been also developed to enable the stabilized round wire for accelerator and fusion magnets. Successfully energized test coils that were manufactured with a wind-and-react technique have demonstrated that a long piece of Cu stabilized RHQT NbAl wire is really available for practical applications.
Hamada, Kazuya; Nakajima, Hideo; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Okuno, Kiyoshi; Suzuki, Tomio; Fujitsuna, Nobuyuki*
Cryogenics, 47(3), p.174 - 182, 2007/03
Times Cited Count：34 Percentile：73.63(Thermodynamics)no abstracts in English
Isono, Takaaki; Hamada, Kazuya; Okuno, Kiyoshi
Cryogenics, 46(9), p.683 - 687, 2006/09
Times Cited Count：5 Percentile：21.24(Thermodynamics)no abstracts in English
Sn coil (CS insert)Inaguchi, Takashi*; Hasegawa, Mitsuru*; Koizumi, Norikiyo; Isono, Takaaki; Hamada, Kazuya; Sugimoto, Makoto; Takahashi, Yoshikazu
Cryogenics, 44(2), p.121 - 130, 2004/02
Times Cited Count：6 Percentile：27.48(Thermodynamics)In order to analyze the quench characteristic of a cable-in-conduit (CIC) conductor that has a sub-cooling channel at the center of conductor cross section, an axisymmetrical two-dimensional calculation model was developed. The test and calculation results of the CS insert were compared regarding the pressure drop and the behavior of the total voltage, temperature and normal zone propagation in the quench. They show good agreement. Therefore, the effectiveness of the calculation model is verified. It was also found that there is coolant convection between the central channel and bundle region even in a steady state. This makes the pressure drop in the central channel larger than that in a cylindrical pipe which has a smooth surface. In addition, it was found that the higher temperature of the coolant flowing through the central channel heats the coolant and the cable in the bundle region. It can be said that the hot coolant flowing through the central channel accelerates normal zone propagation.
Arai, K.*; Ninomiya, Akira*; Ishigooka, Takeshi*; Takano, Katsutoshi*; Nakajima, Hideo; Michael, P.*; Vieira, R.*; Martovetsky, N.*; Sborchia, C.*; Alekseev, A.*; et al.
Cryogenics, 44(1), p.15 - 27, 2004/01
Times Cited Count：3 Percentile：15.22(Thermodynamics)no abstracts in English
Hamada, Kazuya; Takahashi, Yoshikazu; Matsui, Kunihiro; Kato, Takashi; Okuno, Kiyoshi
Cryogenics, 44(1), p.45 - 52, 2004/01
Times Cited Count：21 Percentile：60.45(Thermodynamics)In the ITER Central Solenoid Model Coil (CSMC) and a CS Insert Coil (CSIC) experiment, a pressure drop of the CSIC decreased by about 12% at 40 kA, 10 T and coupling losses indicated an transport current dependence. As a result of pressure drop analysis, an electromagnetic force causes a compressive deformation of cable in a jacket and a new flow passage was generated as a gap between cable and jacket. The cable deformation causes a decrease of a contact electrical resistance between strands and an increase of coupling losses. Taking account of the electromagnetic force dependency of a coupling time constant, calculated coupling losses show a good agreement with measured coupling losses at a pulsed operation of CSMC and CSIC.
Al cable-in-conduit conductorKoizumi, Norikiyo; Takahashi, Yoshikazu; Nunoya, Yoshihiko; Matsui, Kunihiro; Ando, Toshinari; Tsuji, Hiroshi; Okuno, Kiyoshi; Azuma, Katsunori*; Fuchs, A.*; Bruzzone, P.*; et al.
Cryogenics, 42(11), p.675 - 690, 2002/11
Times Cited Count：23 Percentile：64.17(Thermodynamics)In the framework of ITER-EDA, a 13T-46kA NbAl conductor with stainless steel jacket has been developed to demonstrate applicability of an NbAl conductor with react-and-wind technique to ITER-TF coils. The critical current performances of the NbAl conductors were studied to verify that the conductor achieves the expected performance and 0.4% bending strain does not originate degradation. The critical currents were measured at the background magnetic fields of 7, 9, 10 and 11 T at the temperatures from 6 to 9 K. The expected critical currents is calculated using the developed model and the calculation results indicate that the experimental results showed good agreement with the expected critical currents. Accordingly, we can conclude that the fabrication process of this conductor was appropriate and the applicability of the react-and-wind technique was demonstrated.
Yoshida, Kiyoshi; Takigami, Hiroyuki*; Kubo, Hiroatsu*
Cryogenics, 41(8), p.583 - 594, 2001/08
Times Cited Count：8 Percentile：37.26(Thermodynamics)no abstracts in English
Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Nishijima, Gen; Matsui, Kunihiro; Nunoya, Yoshihiko; Takahashi, Yoshikazu; Tsuji, Hiroshi
Cryogenics, 39(11), p.939 - 945, 1999/11
Times Cited Count：3 Percentile：18.71(Thermodynamics)no abstracts in English
Koike, Yoshihiro; Morii, Yukio; Igarashi, Takeshi*; Kubota, Minoru*; Hiresaki, Yu*; Tanida, Koji*
Cryogenics, 39(7), p.579 - 583, 1999/00
Times Cited Count：24 Percentile：69.71(Thermodynamics)no abstracts in English
Sugimoto, Makoto; Kato, Takashi; Isono, Takaaki; Yoshida, Kiyoshi; Tsuji, Hiroshi
Cryogenics, 39(4), p.323 - 330, 1999/00
Times Cited Count：4 Percentile：23.56(Thermodynamics)no abstracts in English
Al superconductors for International Thermonuclear Experimental Reactor (ITER)Yamada, Yuichi*; ; ; ; ; ; ; Koizumi, Norikiyo; Ando, Toshiro; Matsui, Kunihiro; et al.
Cryogenics, 39(2), p.115 - 122, 1999/00
Times Cited Count：39 Percentile：82.53(Thermodynamics)no abstracts in English
Koizumi, Norikiyo; ; K.Macfall*; Matsui, Kunihiro; Takahashi, Yoshikazu; Tsuji, Hiroshi
Cryogenics, 39(6), p.495 - 507, 1999/00
Times Cited Count：4 Percentile：23.56(Thermodynamics)no abstracts in English
Sugimoto, Makoto; Isono, Takaaki; Tsuji, Hiroshi; Yoshida, Kiyoshi; ; Hamajima, Takataro*; Sato, Takashi*; Shinoda, K.*
Cryogenics, 38(10), p.989 - 994, 1998/00
Times Cited Count：4 Percentile：23.78(Thermodynamics)no abstracts in English
Koizumi, Norikiyo; Takahashi, Yoshikazu; Okuno, Kiyoshi; Isono, Takaaki; Tsuji, Hiroshi; Nishi, Masataka
Cryogenics, 37(9), p.487 - 495, 1997/00
Times Cited Count：2 Percentile：16.53(Thermodynamics)no abstracts in English
Koizumi, Norikiyo; Takahashi, Yoshikazu; Nishi, Masataka; Isono, Takaaki; Tsuji, Hiroshi; ; ; Fujioka, T.*
Cryogenics, 37(8), p.441 - 452, 1997/00
Times Cited Count：30 Percentile：78.27(Thermodynamics)no abstracts in English
Koizumi, Norikiyo; Okuno, Kiyoshi; Takahashi, Yoshikazu; Tsuji, Hiroshi; Shimamoto, Susumi
Cryogenics, 36, p.409 - 418, 1996/00
Times Cited Count：18 Percentile：65.00(Thermodynamics)no abstracts in English
Koizumi, Norikiyo; Takahashi, Yoshikazu; Tsuji, Hiroshi
Cryogenics, 36(9), p.649 - 659, 1996/00
Times Cited Count：25 Percentile：73.76(Thermodynamics)no abstracts in English
