Development of Terminal Joint and Lead Extension for JT-60SA Central Solenoid

Manufacturing of central solenoid (CS) for JT-60SA is in progress under the JA-EU broader approach activities. The terminal joints and the lead extensions are used for connecting the power supply and the CS. The terminal joint connects a Nb₃Sn conductor of CS and a NbTi conductor of current feeder. The terminal joint sample was manufactured and tested to verify the design and manufacturing process. The test results indicate that the lap type Nb₃Sn-NbTi joint is available for CS terminal joint. The lead extension is located between the terminal joint and the CS. The extension joint designed by butt joint is used for connecting the CS and lead extension. A repairable extension joint is useful to exchange the terminal joint when a serious problem occurs at the terminal joint. The resistance of the extension joint after the repair process of disconnecting and reconnecting was measured to validate the repairability. The resistance of repaired joint was almost the same as the resistance of original joint. The lead extension is subjected to the electromagnetic force derived from the plasma operation. The lead extension is supported by the CS structure. The structural analysis of the lead extension and its support structure was conducted to confirm the support design. The analysis results showed that the stresses of all components were less than the allowable stress limit. The components for terminals were successfully developed.