Presentation Completion of first CS module for JT-60SA and the plan of cold test

Murakami, Haruyuki  ,  Natsume, Kyohei  ,  Kamiya, Koji  ,  Tsuchiya, Katsuhiko  ,  Kizu, Kaname  ,  Koide, Yoshihiko

2016-11-08
Description
The construction of a full-superconducting tokamak referred as JT-60 Super Advanced (JT-60SA) is in progress under the JA-EU broader approach projects. The magnet system of JT-60SA consists of 18 toroidal field (TF) coils, 4 modules of central solenoid (CS) and 6 equilibrium field (EF) coils. The diameter, the height, the number of layers and the number of turns of CS module are 2.0 m, 1.6 m, 52 layers and 549 turns, respectively. The CS module is composed of 6 octa-pancakes (8 layer pancake) and a quad-pancake (4 layer pancake). Each pancake is connected by the butt type joint. The Nb3Sn conductors are used for CS because of high magnetic field of 8.9 T.The procedure of CS manufacturing is as follows: (1) winding of pancake, (2) heat treatment of pancake, (3) transfer process, which includes turn insulation wrapping, pancake connection and setting of disk-shaped pickup coils, (4) vacuum impregnation of turn insulation, (5) ground insulation wrapping, (6) vacuum impregnation of ground insulation. The procedure of (1)-(3) have been reported in previous paper [1]. The winding accuracy and the temperature control precision during heat treatment met the requirements. The results of preproduction samples showed that the current sharing temperature was the same as the estimation based on strand characteristics, and the butt joint resistance met the requirement of <5 n.The first-time module size vacuum impregnation was conducted using real CS module. During vacuum impregnation process, CS module was pressed in order to increase the bonding strength between turn insulation and conductor. The total insulation thickness of CS module is about 70 mm and the insulation thickness is about 10-20 % shrunk during vacuum impregnation process under the pressurized condition. Therefore the size of first CS module became about 10 mm reduced after vacuum impregnation process. Nonetheless the first CS module is acceptable for JT-60SA because current center can be set to the original position by using additional adjustment spacer. The first CS module will be cooled down and will be energized at the test facility of the National Institute for Fusion Science. The critical current, the joint resistance, the AC loss and the hydraulic characteristics of cooling path is planned to be measured to verify the performance of CS module. In this paper, the manufacturing process of CS module and the plan of cold test of the first CS module will be described.
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