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Sn cable-in-conduit conductorsHemmi, Tsutomu; Harjo, S.; Ito, Takayoshi; Matsui, Kunihiro; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahashi, Yoshikazu; Nakajima, Hideo; Aizawa, Kazuya; Suzuki, Hiroshi; et al.
IEEE Transactions on Applied Superconductivity, 21(3), p.2028 - 2031, 2011/06
Times Cited Count：10 Percentile：49.04(Engineering, Electrical & Electronic)Residual strain in conductors is caused by the difference in the coefficient of expansion between NbSn strands and the jacket over a temperature range of 5 - 923 K. The superconducting properties of strands vary significantly, depending on the strain. It is important to clarify the residual strain as part of the evaluation of superconducting performance. However, the residual strain of strands in the conductor has not been measured so far because of their complicated configuration and their location in a jacket. The engineering materials diffractometer "Takumi" in J-PARC can measure residual strain with a relative accuracy of around 0.02%, using neutron diffraction. In this study, the Takumi was applied to the measurement of residual strain in strands for the ITER TF conductor. Results indicate that the residual strain of strands in the conductor can be determined, thereby clarifying the mechanism of residual strain and its relationship to superconducting performance.
Sn conductor developed for the ITER TF coilsNunoya, Yoshihiko; Nabara, Yoshihiro; Yoshikawa, Masatoshi*; Matsui, Kunihiro; Hemmi, Tsutomu; Takahashi, Yoshikazu; Isono, Takaaki; Koizumi, Norikiyo; Nakajima, Hideo; Stephanov, B.*; et al.
IEEE Transactions on Applied Superconductivity, 21(3), p.1982 - 1986, 2011/06
Times Cited Count：23 Percentile：70.26(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) has developed ITER TF NbSn conductors that fulfill ITER requirements and then commenced fabricating conductors to be used for ITER TF coils. As a qualification of conductor fabrication, two full-size conductor samples named as JATF4 were prepared and tested by the SULTAN facility at CRPP in Switzerland. The length of the samples was about 3 m, and temperature sensors and voltage taps were attached on conductors to measure the current sharing temperature (Tcs). The measurement was performed at the beginning of the test campaign, during cyclic test, and at the end of the campaign that corresponded to after once warm up and cool down. The Tcs values electrically assessed by the agreed procedure at outer magnetic fields of 10.78 T were 6.5 K and 6.2 K at the beginning and 6.1 K and 6.0 K at the end of the campaign for each conductor, respectively. These values concluded that the conductors have enough Tcs margin to satisfy the criterion of 5.7 K as ITER TF conductor, and conductor fabrication is qualified. Detail of the test results will be presented and discussed.
Murakami, Haruyuki; Ichige, Toshikatsu; Kizu, Kaname; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Yanagi, Nagato*; Mito, Toshiyuki*; et al.
IEEE Transactions on Applied Superconductivity, 21(3), p.1991 - 1994, 2011/06
Times Cited Count：2 Percentile：18.09(Engineering, Electrical & Electronic)no abstracts in English
Kajitani, Hideki*; Ishiyama, Atsushi*; Koizumi, Norikiyo; Murakami, Haruyuki; Nakajima, Hideo
IEEE Transactions on Applied Superconductivity, 21(3), p.1964 - 1968, 2011/06
Times Cited Count：5 Percentile：33.08(Engineering, Electrical & Electronic)The critical current of cable-in-conduit conductor (CICC) for ITER TF coil was measured using SULTAN test facility. However, it was found that a non-uniform current distribution was established due to a non-uniform joint resistance. To more precisely evaluate critical current performance, solder filling joint was applied. To study the effect of solder filled joint on the current distribution, the authors developed a new analysis model. The lumped circuit model and distributed circuit model were used for the conductor and joint, respectively, and they are combined. This allow us to avoid iteration to solve distributed circuit equation, resulting in much reduction of calculation time. The simulation results show that although non-uniform current distribution can be established by ramping current, it is improved at current sharing temperature. Thus, the efficiency of solder filling joint is indicated.
