H. Murakami

K. Kizu

K. Takahata

K." Yoshida

S. Hamaguchi

S. Imagawa

T. "Obana

T. Mito

National Institute for Fusion Science (NIFS-Repository)

20Hall sensors800 1000Joint region for the pancake jointTime[s]200 400 600L-.I...L.L----'------'------'------'-----'------'----------'------'-----'------'-----'------L-.I-----L-.I..----'...L.L----'------L-'------' 0200 400 600 800 1000 1200E=:'g 100·i 50??"'Cl;>-.(1)?.S -50?tQu -100??? -150?? -200?cS 100? 200?? 50;.a;>-. 15 n(1) §i:l a.S -50"'d10 fQ)t;::1u -100??bJ) -150roS? -200r:/)i"43? ? i"43? iHS-3: ?? HS-7: iHS-82TI T T x... ... ...--- -......\HS-l: 'HS-2 HS-5i :HS-672 72 CICCTime[s]1--0- 81 ---<>-B3 -v-B5 --zj- 87 1-0- B2 -0-B4 -t:rB6 ? B8150 ????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 25Unit:mm150 r=;::::;::::::;::::::::;=;::::;::::;:::::;::::;:::;::::;:::::::;::::;::::;:::;:::::::;:::::::::;::::;:::;::::;::::;::::::;::., 25Fig. 2. Cross-section of the conductors near the joint.Tenninal EF-H coil conductor Cooling ?????? ??yFig. 1. Schematic view of the joint sample.Joint region for the tenninal jointEF-H coil conductor?: Transport currentmagnetic field without the external magnetic field. Underthe external magnetic field of 3 T, the y-directional selfmagnetic field is enhanced in the space between the CICconductors and is weakened outside the space.1) Yoshida, K.,: Physica C 470 (2010) 1727.Fig. 3. Measurement results of the self magnetic fieldwithout the external magnetic field.Fig. 4. Measurement results of the self magnetic fieldunder the external magnetic field of 3T.In superconducting fusion magnets consisting of cable-in-conduit (CIC) conductors, the joint is an importantcomponent which influences the performance of themagnet. To minimize electrical resistance and AC loss atthe joint between the conductors, various joint types for themagnet have been developed. In the case of JT-60SAEquilibrium Field (EF) coils, a shake-hands lap joint waschosen as the joint type [1]. In this study, in order tounderstand the electromagnetic behavior of the CICconductor, the joint sample was used to measure the selfmagnetic field near the CIC conductor's shake-hands lapjoint.Fig. 1 shows the joint sample, the configuration ofwhich is a racket shape of 300 mm in diameter at thecircular part. In the joint, a saddle spacer of oxygen-freecopper is located between the conductors removing Niplating. The superconducting test facility at NIFS was usedas an experimental setup. The test facility can deal withtesting of superconductors cooled by LHe, under anexternal magnetic field generated by a superconductingsplit coil. The joint sample was installed into the gap of thesplit coil so as to fit the center of the joint sample with thatof the split coil, and immersed in LHe. As illustrated in Fig.1, the joint sample is equipped with Hall sensors. Fig.2shows the layout of the Hall sensors arranged around theCIC conductors near the joint. In this study, magnetic fieldsin the y direction were measured with the calibrated Hallsensors (HS-l, HS-2,· • ., HS-8), the models of which areLakeShore HGCT-3020 and F.W. BELL BHT-921.Self magnetic field measurements of the joint samplewere carried out with and without the external magneticfield generated by the split coil. The joint sample wasenergized up to 20 kA, held for 500 sec, and thendegaussed. When the joint sample was subjected to theexternal magnetic field, the self magnetic fields wereobtained by removing the external magnetic field from rawdata. Fig. 3 shows the result of the self magnetic fieldwithout the external magnetic field. In Fig. 3, the symbolsB1, B2,· • ., B8 indicate the self magnetic fields at eachhall sensor HS-l, HS-2,· • ., HS-8. The currents in eachof the CIC conductors surrounded by the Hall sensors flowin opposite directions, so that the y-directional selfmagnetic field at the Hall sensors HS-2, HS-4, HS-5, HS-7,which are located between CIC conductors, are larger thanthose at the Hall sensors HS-l, HS-3, HS-6, HS-7. Fig.4shows the results of the self magnetic field in the jointwhich was subjected to the external magnetic field of 3 T.When the external magnetic field is 3 T, the distribution ofthe self magnetic field is different from that of the self276§24. Measurements of Self Magnetic Field on NbTi Cable-in-conduit Conductors near the Shake-hands Lap JointObana, T., Takahata, K., Hamaguchi, S., Mito, T., Imagawa, S.,  Kizu, K., Murakami, H., Yoshida, K. (JAEA)

Measurements of Self Magnetic Field on NbTi Cable-in-conduit Conductors near the Shake-hands Lap Joint

Measurements of Self Magnetic Field on NbTi Cable-in-conduit Conductors near the Shake-hands Lap Joint

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