Current sharing temperature of central solenoid conductor for JT-60SA under repetition excitation

繰り返し励磁におけるJT-60SA用CS導体の分流開始温度

村上 陽之; 木津 要; 市毛 寿一; 神谷 宏治; 土屋 勝彦; 吉田 清; 尾花 哲浩*; 濱口 真司*; 高畑 一也*; 柳 長門*; 三戸 利行*; 今川 信作*

Murakami, Haruyuki; Kizu, Kaname; Ichige, Toshikatsu; Kamiya, Koji; Tsuchiya, Katsuhiko; Yoshida, Kiyoshi; Obana, Tetsuhiro*; Hamaguchi, Shinji*; Takahata, Kazuya*; Yanagi, Nagato*; Mito, Toshiyuki*; Imagawa, Shinsaku*

JT-60SA装置の中心ソレノイド(CS)導体は、最大9Tの磁場を受けるため、NbSn素線を用いたケーブル・イン・コンジット導体により製作される。CS導体の量産に先立ち、超伝導特性の確認を目的に、日本原子力研究開発機構(JAEA)と核融合科学研究所(NIFS)が共同で、分流開始温度(Tcs)測定試験及び4000回までの繰り返し通電を実施した。今回実施したTcs試験及び繰り返し通電試験より、CS導体は十分な超伝導特性を持つこと、繰り返し励磁に対して超伝導特性の劣化を示さないことがわかった。また、本試験結果をもとに実機運転におけるCS導体の温度マージン解析を行った結果、十分な温度マージンを持って運転できることが確認できた。以上より、CS導体の設計及び製造プロセスに問題がないことが確認できたことから、CS導体の量産を開始した。本講演では、Tcs測定試験,繰り返し通電試験及び温度マージン解析の結果について報告する。

The JT-60U magnet system will be upgraded to the superconducting coils (JT-60SA) in the Broader Approach (BA) project. The JT-60SA magnet system has 18 Toroidal Field (TF) coils, a Central Solenoid (CS) with 4 modules and 6 Equilibrium Field (EF) coils. The CS conductors are designed with NbSn cable in conduit (CIC) conductor because the magnetic field of CS is up to 8.9 T. The short CS conductor was manufactured and processed into the performance verification test sample. The Tcs test results indicate that the initial Tcs of the CS conductor is about 2 K higher than the minimum requirement of the conductor design. In addition the Tcs after the repetition excitation is more important issues for the CS conductor because the CS conductor is made of NbSn strand. The Tcs changes with the repetition excitation and the influence of the warm up and cool down process on the Tcs were measured. The test results show that there is no degradation while the repetition excitation tests. The AC loss test of the CS conductor was also performed for precise estimation of the conductor heat loads. The Tcs margin analysis of the CS conductor was conducted based on the latest conductor heat loads. The analysis results show that the CS conductor has enough Tcs margin during the JT-60SA operation. These results show that the design and the manufacturing process of the CS conductor satisfy its requirements. Thus CS conductors for the CS1 module have been manufactured on the mass production process. In this paper, the Tcs test, the repetition excitation test, the AC loss test and the Tcs margin analysis of the CS conductor are described.