The outline of Large Coil Task (LCT) is described. This work is being carried out as an international collaboration under direction of the International Energy Agency for the purpose of superconducting toroidal coil development for fusion reactor. The common specification and the test conditions are explained. The characteristics of six coils, which are designed on the basis of specification and test condition, are compared. The systems and capacity of the Large Coil Test Facility (LCTF), which is being completed at Oak Ridge National Laboratory, is introduced.
At JAERI, the cluster test program (CTP) was started in 1977 as a development of high field superconducting toroidal coil in tokamak fusion machine. The cluster test facility (CTF) for this CTP has been designed and constructed. The coil system of the CTF, in which a test module coil (TMC) is tested, is composed of two cluster test coils (CTC) simulated a toroidal coil array. In this paper, the feature of the CTP and the design of two CTC of the CTF are described.
This paper describes system design of the Cluster Test Facility (CTF) which is a test facility to develop high field toroidal coils more than 12T for fusion reactor. The CTF is composed of two Cluster Test Coils (CTC), a 100-l/h helium cryogenic system, a vacuum system, a 3 KA DC power supply and protection system, and a PDP-11/34 computer system for data acquisition and control. The purpose of the CTF is not only to test the Test Module Coil (TMC) which is a test coil to be developed, but also to develop and verify total technology required for superconducting coil system for the tokamak reactor at the Japan Atomic Energy Research Institute (JAERI).
This paper describes the thermal and mechanical test results of the Cluster Test Coil (CTC) tested in the Cluster Test Facility (CTF). CTF is the large scale test facility which was constructed for the development of high field superconducting toroidal magnet for fusion machine. Two Cluster Test Coils (CTC-1 and CTC-2), which have average diameter of 1.5m, and maximum field of 7T, were cooled down and warmed up automatically by a computer system. Two CTC were charged up to the nominal superconducting current of 2, 145A without training. Mechanical characteristics of CTC in charging state were studied by strain gauge and Acoustic Emission (AE) measurement and the results were compared with the calculation.
This paper describes design, verification tests, and construction of the Japanese test coil for the Large Coil Task (LCT). Japan Atomic Energy Research Institute (JAERI) signed on the LCT international agreement under the International Energy Agency (IEA) in 1978, and since then JAERI has been working to develop the Japanese LCT coil to explore the problems of design and construction of tokamak toroidal coil. Based on the common requirements of the LCT, the Japanese LCT coil was designed to be a pool-cooled NbTi fully-stabilized coil whose operating current is 10, 220A at 8T. Through research and development of the Japanese LCT coil, new advances in the superconducting coil technology were obtained, such as mechanically and chemically treated conductor surface that has high heat transfer about four times as much as usual ones, nitrogen-strengthened stainless steel that has the yield strength twice as much as usual stainless steel, NbTi filaments those have the critical current density twice as much as those before LCT, and so on. These advances have enabled to construct the Japanese LCT coil and it was completed in the spring of 1982. During the construction of the coil, new fabrication techniques were obtained to wind large current conductor into a mechanically rigid coil and thus to construct a totally stable large coil.
This paper gives an overall view of the Superconducting Engineering Test Facility (SETF) at JAERI. SETF is composed of a cryogenic system, a vacuum system, a power supply with protection system, and a data acquisition system. The purposes of SETF are to test not only the Japanese LCT coil, but also high-field, large current toroidal coils or high-energy pulsed coils. The capacity of helium liquefier/refrigerator is 350l/h or 1.2kW at 4.5K. Vacuum tank has 5m diameter and 8m height. The DC power supply and pulsed power supply have the maximum capacity of 30kA-12V, and 3.2kA-300V, respectively. The PDP-11/70 computer system has 680 channels for data processing. The facility was successfully operated during the cool-down, warm-up, charging, and dumping of the LCT coil. And these tests results demonstrate the high reliability of the facility. Automatic control of the cryogenic system and the leakage of helium gas from the feedthroughs are also described.
This paper describes thermal and system design of the 350l/h helium cryogenic system which was constructed for testing the Japanese LCT coil at the Japan Atomic Energy Research Institute (JAERI). The cryogenic system, which is a second step to develop a large and reliable helium cryogenic system for fusion, was designed to have a maximum refrigeration capacity of 1, 000W or a maximum liquefaction capacity of 300l/h at 4.5K; this permits to cool the LCT coil down to 4K in 120 hours. Themodynamic cycle and control system were specified in accordance with technical informations obtained from the Cluster Test Facility. The design and construction work of the system were started in May, 1980 and the first test to check the performances was carried out from June 12 to 16 in 1981 at the JAERI. The measured performances are described in this paper.
This paper describes thermal results obtained in the domestic test of the Japanese LCT coil which was constructed at the Japan Atomic Energy Research Institute (JAERI) in order to develop large superconducting coils for fusion in international collaboration proposed by the IEA. The domestic test was carried out from May 13 to June 17 in 1982 by using the test facility named as SETF (Superconducting Engineering Test Facility) which was composed of a 350-l/h helium cryogenic system, a vacuum system, a 30KA-DC power supply and protection system, and a PDP-11/70 computer system. The cool-down characteristics, heat load, fast discharge characteristics, stability, and warm-up characteristics of the LCT coil were successfully measured in the test. The details of thermal test results acquired in the cool-down, heat load measurement, fast discharge, and warm-up, and the comparison between measurements and calculations are described in this paper.
The domestic test of the Japanese LCT coil was carried out in 1982. During this test, the coil was charged up to the single coil's 100% state (10.22kA, 6.4T, 106MJ) four times and experienced no quenche. At the 100% charging state, coil stability was tested by using heaters installed in the conductor. A half turn length normal zone (about 5m) generated by heaters was spontenously disappeared in 2 second. This normalized zone included the highest magnetic field position. The transport current which gives the stable limit is extraporated to be about 12.5kA at 8T by this test result. The dump test was carried out also from the 100% charging state. At that time, about 90% of the coil's stored energy was extracted by the dump resistor and the coil was not damaged.
Domestic test of the Japanese LCT coil was carried out in Japan Atomic Energy Research Institute (JAERI). Mechanical characteristics of the test coil were measured during the cool-down, warm-up and charge-up test by strain gauges and displacement gauges attached directly to the test coil. During the cool-down test, the maximum temperature difference in the test coil was controlled within 96K in order to avoid excessive thermal strain. Maximum thermal strain in conductor and helium vessel in the circumferential direction was 170ppm, and-950ppm in cool-down test. The test coil was able to charge up to the rated current in very stable, and run-away of strain was not observed both in conductor and in helium vessel. The test results obtained in rated current operation were compared with the calculation. Some differences in the distribution of conductor strain were found by the comparison, and several technical subjects both in measurement and in calculation became clear. As the result of the domestic test, mechanical data base for large coil design was accumulated.