The paper describes the design, construction and long-term perfomances of the 6m-superconducting solenoid and associated supercritical He cooling system for the muon channel of the Meson Science Laboratory, University of Tokyo. The basic new and novel concept of this system compared to the SIN system stays in the following points: 1) the supercritical He is generated by the “Single” heat exchanger located inside the refrigerator cold box, therby simplifying the total cooling system; 2) the iron return yoke is placed at room temperature, reducing substantially the cold weight; 3) after the careful design of the system, a large mass flow of 5.0gr/s is adopted, minimizing cool-down time, etc. In this report, the emphasis is given for the potential use of this “Simplified” supercritical He cooling for the large-scale superconducting solenoid. Associated design principle as well as required thermodynamical calculations are given. Through the successful and maintenance free operation in the period of 1980 to 1984 amounting to 9000h, we have confirmed the excellence of the whole system.
In JAERI, as one of superconducting toroidal coil development works for a tokamak fusion machine, the Cluster Test Program is under way. The first Test Module Coil (TMC-I) in this program has been constructed in 1982. The TMC-I, whose winding inner diameter is 60cm, has been fabricated with a double pancake winding method using a reacted multifilamentary Nb3Sn conductor. Up to now, experiments of the TMC-I were carried out on cooling-down, current charge, stability, manual dumping and out-of-plane force. The TMC-I was stably operated in 11.1T with the current of 6kA and the current density in the winding of 30A/mm2. A total stored energy was 46MJ at 11.1T. 192cm length normal zone, generated by heat-input in the innermost turn, recovered spontaneously to superconducting state in 6.3s. From these results, it was demonstrated that a multifilamentary Nb3Sn conductor is applicable to large-current and large-size coils.
The test module coil (TMC-I) is the first test coil wound with multifilamentary Nb3Sn conductor in order to demonstrate high field superconducting toroidal field coils for fusion. The TMC-I was constructed in 1982 and the electrical, mechanical, and thermal characteristics were tested at the magnetic field of 10.2T by using the Cluster Test Facility (CTF). Thereafter, the TMC-I was successfully charged up to 11.1T in the Cluster Test Facility reinforced by adding two more back-ground coils (CBC) to the existing Cluster Test Coils (CTC). This paper describes thermal characteristics obtained in the cool-down, the heat load measurements, and the manual dump test of the TMC-I.