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Koizumi, Norikiyo; Nunoya, Yoshihiko; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 16(2), p.831 - 834, 2006/06
Times Cited Count：24 Percentile：70.93(Engineering, Electrical & Electronic)no abstracts in English
Al insertKoizumi, Norikiyo; Nunoya, Yoshihiko; Takayasu, Makoto*; Sugimoto, Makoto; Nabara, Yoshihiro; Oshikiri, Masayuki*; CS Model Coil Test Group
Teion Kogaku, 38(8), p.399 - 409, 2003/08
A NbAl insert was developed to demonstrate the applicability of a NbAl conductor and wind-and-react method to a TF coil of a fusion reactor by artificially applying 0.4% bending strain to the conductor after its heat treatment. The critical current test results show that the effective strains applied to the strands is almost zero. Then, the validity of the react-and-wind method was demonstrated. In addition, while an unexpected strain, which was proportional to electromagnetic force, was observed in the same scale NbSn conductor, such strain did not exist in the NbAl conductor. This shows a NbAl conductor is suitable to the application to large magnets, such as the TF coil. Furthermore, the effect of the current transfer among the strands on the critical current evaluation is studied by developing a numerical analysis code, KORO. The results figure out that the critical current of a large cable-in-conduit conductor can be easily evaluated assuming the uniform current distribution if the conductance among the strands is 10E5 S/m or less.
Isono, Takaaki; Nunoya, Yoshihiko; Ando, Toshinari*; Okuno, Kiyoshi; Ono, Michitaka*; Ozaki, Akira*; Koizumi, Tsutomu*; Otani, Nozomu*; Hasegawa, Takayo*
IEEE Transactions on Applied Superconductivity, 13(2), p.1512 - 1515, 2003/06
Times Cited Count：21 Percentile：67.87(Engineering, Electrical & Electronic)Japan Atomic Energy Research Institute has started development work on a large current conductor using high Tc superconductor (HTS) aiming at a fusion power reactor after the International Thermonuclear Experimental Reactor (ITER). HTS has a capability to produce a magnetic field of higher than 16 T, which is required in such a fusion power reactor. A trial fabrication of a 10-kA 12-T conductor was started using round Ag-alloy sheathed Bi-2212 strands, which has best performance at 4.2K, 16T at present. The conductor has about 34-mm diameter, and is composed of 729 HTS strands. Operating temperature is designed at not only 4 K but also 20K. The conductor sample is indirectly cooled and is solder-coated on the surface to use specific heat of the lead as much as possible, which at 20 K is almost comparable with specific heat of SHe at 4.5K, 0.6MPa. From the tests of the conductor, the fabrication of large HTS conductor and 10kA operation at 12 T and about 12.5 K were successfully performed and the possibility of HTS to use fusion application was demonstrated.
Nunoya, Yoshihiko; Isono, Takaaki; Sugimoto, Makoto; Takahashi, Yoshikazu; Nishijima, Gen*; Matsui, Kunihiro; Koizumi, Norikiyo; Ando, Toshinari*; Okuno, Kiyoshi
IEEE Transactions on Applied Superconductivity, 13(2), p.1404 - 1407, 2003/06
Times Cited Count：10 Percentile：49.54(Engineering, Electrical & Electronic)Analysis of critical current (
) and current sharing temperature (
) was performed to the ITER Center Solenoid (ITER-CS) Model Coil Insert. Voltage behavior related to normal state transition of the conductor during or measurement has not been well understood especially in case of such a large cable with more than one thousand strands as this coil. From the detailed analysis of the voltage behavior of the coil, it is found that the average of electric field in the strand-longitudinal direction over the conductor cross section is equal to the average field of one strand along the conductor length, whose integral was measured by the voltage taps during the coil test. It is because twist pitch of the cable is less than the range of longitudinal field variation in this case. This evaluation method can estimate voltage behavior and predict and values, which are important parameters for the design of a large conductor coil, based on the property of strands composing the conductor.
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：64.85(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.
Al strand in high magnetic fieldsKeys, S.*; Koizumi, Norikiyo; Hampshire, D.*
Superconductor Science and Technology, 15(7), p.991 - 1010, 2002/07
Times Cited Count：39 Percentile：82.22(Physics, Applied)The critical current density of a jelly-roll NbAl strand was measured at first as a function of magntic field, temperature and strain. The equation to estimate its critical current density has been derived from these test results. The magenti fields, temperatures and strains were less than 15 T, less than 14 K and -1.8 - 0.7% in the experiment.
Al multifilamentary strand fabricated by a jelly-roll methodTakahashi, Yoshikazu; Koizumi, Norikiyo; Nunoya, Yoshihiko; Takaya, Yoshiyuki*; Tsuji, Hiroshi
IEEE Transactions on Applied Superconductivity, 12(2), p.1799 - 1803, 2002/06
Times Cited Count：5 Percentile：35.18(Engineering, Electrical & Electronic)JAERI has been developing jelly-roll processed multifilamentary NbAl/Cu strands for the Toroidal Field (TF) coils of fusion tokamak machines since 1986, in cooperation with industries. One ton of mass-produced strands were successfully manufactured for the 13T-46kA NbAl insert which will be tested using the ITER Central Solenoid model coil. The critical current of the Nb3Al strand developed for the ITER project was measured in temperatures from 4.2 K to 15 K and in applied magnetic fields up to 16 T. An empirical equation for the critical current density was devised using these data and the pinning force scaling method. Good agreement between this equation and the measured data is obtained in the operating condition of the ITER machine. The equation is useful in evaluating the performance of the full-size conductor that consists of 1,152 strands and in establishing the optimum design criteria for the conductor in fusion machines.
Nakajima, Hideo
Chitan, 50(2), p.98 - 101, 2002/04
no abstracts in English
SrCaCuO
single crystals by Kr
-ion irradiation followed by thermal annealingOgikubo, Koji*; Uchida, Yukihiro*; Terai, Takayuki*; Yamaguchi, Kenji*; Yamawaki, Michio*; Hayashi, Kimio
Tokyo Daigaku Kogakubu Sogo Shikenjo Nempo, 59, p.91 - 95, 2000/12
no abstracts in English
Kaminaga, Masanori; Yamamoto, Kazuyoshi; Sudo, Yukio
Journal of Nuclear Science and Technology, 35(12), p.943 - 951, 1998/12
Times Cited Count：21 Percentile：82.63(Nuclear Science & Technology)no abstracts in English
SrCaCuO
tapesKazumata, Yukio*; Okayasu, Satoru; Sataka, Masao; *
Physical Review B, 58(9), p.5839 - 5847, 1998/09
Times Cited Count：7 Percentile：40.88(Materials Science, Multidisciplinary)no abstracts in English
Isono, Takaaki; Nunoya, Yoshihiko; Hamada, Kazuya; Matsui, Kunihiro; Sugimoto, Makoto; Koizumi, Norikiyo; *; *; *; *; et al.
Teion Kogaku, 33(7), p.473 - 478, 1998/00
no abstracts in English
Kaminaga, Masanori; Yamamoto, Kazuyoshi; Sudo, Yukio
Proceedings of 8th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-8), Vo.3, p.1815 - 1822, 1997/00
In research reactors, plate-type fuel elements are generally adopted so as to produce high power densities and are cooled by a downward flow. A core flow reversal from a steady-state forced downward flow to an upward flow due to natural convection should occur during operational transients such as "Loss of the primary coolant flow". Therefore, in the thermal hydraulic design of research reactors, critical heat flux (CHF) under a counter-current flow limitation (CCFL) or a flooding condition are important to determine safety margins of fuel against CHF during a core flow reversal. The authors have proposed a CHF correlation scheme for the thermal hydraulic design of research reactors, based on CHF experiments for both upward and downward flows including CCFL condition. When the CHF correlation scheme was proposed, a subcooling effect for CHF correlation under CCFL condition had not been considered because of a conservative evaluation and a lack of enough CHF data to determine the subcooling effect on CHF. A too conservative evaluation is not appropriate for the design of research reactors because of construction costs etc. Also, conservativeness of the design must be determined precisely. In this study, therefore, the subcooling effect on CHF under the CCFL conditions in vertical rectangular channels heated from both sides were investigated quantitatively based on CHF experimental results obtained under uniform and nonuniform heat flux condition. As a result, it was made clear that CHF in this region increase linearly with an increase of the channel inlet subcooling and a new CHF correlation including the effect of channel inlet subcooling was proposed.
Sn wires for the ITER*; *; *; *; *; Nishi, Masataka; Yoshida, Kiyoshi; Isono, Takaaki; Tsuji, Hiroshi
Teion Kogaku, 32(4), p.167 - 172, 1997/00
no abstracts in English
CuO ceramic by electron irradiation under remanent magnetic fields*
Japanese Journal of Applied Physics, 35(6B), p.L766 - L769, 1996/06
Times Cited Count：2 Percentile：15.08(Physics, Applied)no abstracts in English
*; Takahashi, Yoshikazu; Nishi, Masataka; Isono, Takaaki; Tsuji, Hiroshi
JAERI-Research 96-013, 14 Pages, 1996/03
JAERI-Research-96-013.pdf:0.79MB
no abstracts in English
Sugimoto, Makoto; Isono, Takaaki; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nishi, Masataka; Okuno, Kiyoshi; Yoshida, Kiyoshi; Nakajima, Hideo; Ando, Toshinari; Hosono, Fumikazu*; et al.
IEEE Transactions on Magnetics, 30(4), p.2042 - 2045, 1994/07
Times Cited Count：1 Percentile：24.73(Engineering, Electrical & Electronic)no abstracts in English
Al cable-in-conduit conductor for fusion machinesTakahashi, Yoshikazu; Sugimoto, Makoto; Isono, Takaaki; Nakajima, Hideo; Ando, Toshinari; Oshikiri, Masayuki*; Hosono, Fumikazu*; *; *; Hanawa, Hiromi*; et al.
IEEE Transactions on Magnetics, 30(4, Part2), p.2531 - 2534, 1994/07
no abstracts in English
CuO
thin film; Iwase, Akihiro; Iwata, Tadao; Maeta, Hiroshi; *; *
J. Supercond., 7(1), p.241 - 242, 1994/00
no abstracts in English
CuO; Okayasu, Satoru; *
Superconductors, Surfaces and Superlattices (Trans. of Materials Research Soc. Jpn., Vol. 19A), 0, p.413 - 416, 1994/00
no abstracts in English
