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Yanggu, South Korea

Tomone S.,Japan Atomic Energy Agency | Yoshihiro N.,Japan Atomic Energy Agency | Yoshikazu T.,Japan Atomic Energy Agency | Masayuki O.,Japan Atomic Energy Agency | And 7 more authors.
Physics Procedia | Year: 2015

The Japan Atomic Energy Agency (JAEA) is procuring Central Solenoid (CS) conductorsfor all modules forITER. The superconducting properties of the Nb3Sn CS conductors will have to sustain 60,000 electromagnetic (EM) cycles. The current sharing temperatures (Tcs) were stable with EM cycles in short twist pitch conductors.However, the short twist pitch and tight cabling increases indented strands at the contact point between strands before heat treatment. The results of Ic measurement on artificially indented Nb3Sn strands indicate that Ic was almost constant within a critical depth of the indentations. © 2015 The Authors.

Suwa T.,Japan Atomic Energy Agency | Nabara Y.,Japan Atomic Energy Agency | Ozeki H.,Japan Atomic Energy Agency | Hemmi T.,Japan Atomic Energy Agency | And 18 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

Japan Atomic Energy Agency (JAEA) is procuring 100% of the ITER Central Solenoid (CS) conductors. The CS conductor is required to maintain the performance under 60 000 pulsed electromagnetic cycles. JAEA tested two internal-tin Nb3Sn conductors for the CS at the SULTAN test facility. As a result of destructive examination, the twist pitches of both of the cables satisfied requirements of the ITER Organization (IO). The current sharing temperatures Tcs of each sample were 6.6 and 6.8 K before cyclic operation, and the Tcs values were 6.8 and 6.9 K after 9700 electromagnetic cycles, including three warm-up/cooldowns, respectively. The Tcs performance of both samples satisfied the IO requirement. The ac losses of CSKO1-C and CSKO1-D were approximately half of typical bronze-route CS conductors at 2 and 9 T. The ac loss at 45.1 kA after the cycling was 1.5 times higher than that without the transport current. An almost constant strain of the jacket was observed after the test as a result of the residual strain measurement. Therefore, the deformation of the cable might have been homogeneous along the conductor axis. Because of the higher Tcs of CSKO1-D than CSKO1-C, JAEA started the manufacturing of the CS conductor with the same specification as CSKO1-D. © 2002-2011 IEEE.

Kwon S.P.,National Fusion Research Institute | Sim K.-H.,Kiswire Advanced Technology Ltd. | Ma Y.J.,National Fusion Research Institute | Park S.-H.,National Fusion Research Institute | And 6 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2015

The ITER tokamak being constructed in southern France will incorporate a central solenoid (CS) coil consisting of 6 modules stacked one on top of the other. Each module will be constructed from round-in-square Nb3Sn based superconducting cable-in-conduit conductor (CICC). Production of CS conductor for the ITER tokamak had been delayed due to discoveries of faster than expected performance degradation. Investigations into mitigating this shortfall have included using internal-tin (IT) route Nb3Sn strand in place of the bronze (BR) route strand that was originally proposed. Prototype ITER CS conductor samples have been produced using IT route Nb3Sn strand in conjunction with cabling optimization, and conductor performance tests show that they satisfy ITER performance requirements. One of the suppliers of IT route ITER Nb3Sn strand, which will be supplying superconducting strand for ITER CS conductor, is Kiswire Advanced Technology Ltd. (KAT) of Daejeon, Korea. The characteristics of their prototype Nb3Sn strand for ITER CS conductor are presented. Furthermore, performance degradation of the CS strand due to possible strand deformations during the cabling process was also investigated. The results show similarities as well as differences with recent results obtained with BR route Nb3Sn strand. However, direct interpretation of the strand deformation versus performance results may not lead to correct predictions of cable performance because of the strand contact interaction mechanism investigated. © 2014 IEEE.

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