G. Vecsey

Status report on the 12 T split coil test facility SULTAN (for NET magnets)

The third phase of upgrading of the superconductor test facility SULTAN into a split coil system (SULTAN III) is in progress. SULTAN III consists of two coil packages, each containing three concentrically mounted superconducting solenoids. Together they will produce a field of nearly 12 T between the two coil packages, inside a solenoid bore of 58 cm. The outermost 6 T coils have NbTi conductors, whereas the inner 9 T and 12 T coils are made of A-15 cables. All Nb/sub 3/Sn coils are manufactured by the react-and-wind technique. The split coil arrangement, in connection with a sophisticated sample insert containing a 50 kA superconducting transformer, will allow testing of short samples of high-current-carrying superconductors, e.g. for fusion applications. The sample insert was designed to allow changing the samples within a few hours without warming up the whole magnet system. The authors discuss the present status and potential of SULTAN III. >

First performance test of the 12 T split coil test facility SULTAN III

The test facility SULTAN III at PSI is primarily devoted to qualification of full-size conductors developed for the next generation of fusion experimental devices. Very recently, the facility generating magnetic fields in excess of 11 T was completed and successfully tested. The split coil arrangement with a radial access of 94 mm*144 mm is ready to perform tests of superconductors carrying currents up to 50 kA at temperatures between 4.5 K and 7 K. First results on a fusion dedicated prototype conductor are presented. The main features of the SULTAN III facility are summarized.<<ETX>>

Status report on the forced flow high field test facility SULTAN

The construction of the Test Facility SULTAN - a common action of three European laboratories: ENEA (I-Frascati), ECN (NL-Petten) and SIN (CH-Villigen) is near completion. In this paper the status of the contributions of the different partners is described: (a) The SIN part of the facility, the cryogenic system the current leads, the power supplies and the data acquisition system has been put into operation. Results of these tests are presented. (b) The background field will be generated by two concentric solenoids. The ENEA contribution is concerned with the realization of the outer solenoid. This coil, which has been recently completed, will provide a 6 T field in the useful region, the remaining 2 T being supplied by the coaxial ECN insert coil. Details of the design, winding technique, hydraulic circuitry as well as instrumentation of both coils will be given and discussed. In addition the future upgrading to 12 T is outlined.

Transient stability results for Nb/sub 3/Sn cable-in-conduit conductors

Transient stability experiments are carried out on a Nb/sub 3/Sn cable-in-conduit conductor in the SULTAN test facility. A disturbance of variable duration is applied by a pulsed field, transverse to the conductor axis. The results show a high tolerance to large field transients even in the current sharing regime, well correlated with the extremely low coupling loss. Local disturbances, nonhomogeneous over the cable cross section, are also applied to investigate the ability to redistribute the current locally among strands.

FINAL TESTS OF THE SULTAN 12T FACILITY IN THE SPLIT COIL CONFIGURATION

As already reported (Ref. 1), in the framework of the conductor development undertaken by the NET Team as a part of the RD ii) the construction of two intermediate 9T Nb3Sn coils and iii) the construction of a 12T Nb3Sn solenoid in addition to a similar existing coil. The whole system allows the insertion of samples in the radial direction with a useful measurement length of the conductor of about 60 cm at 12T. All the above-mentioned steps of the program have been accomplished, so the system has been assembled and inserted in its cryostat. After a series of preliminary cryogenic and electrical tests, the magnet system was succesfully tested reaching the field design value. It represents the worlds most powerful high-field test facility presently in operation.

Successful operation of the Nb/sub 3/Sn Swiss insert coil for the 12 tesla Sultan test facility

The design and fabrication principles of the first high-field insert for SULTAN are described and the results of the coil test performed in the background field of the SULTAN facility are presented. The Swiss Nb/sub 3/Sn insert coil is the first of three A15 coils of SULTAN planned to demonstrate the feasibility of high-current, high-field superconductor technology for fusion devices in Europe. The forced-flow, steel-reinforced conductor is based on an external diffusion Nb/sub 3/Sn cable, and is reacted before conventional fabrication of the 60-cm bore coil. During tests in the background field of SULTAN, the coil reached the design current of 6 kA without training. It could only be turned normal by raising the temperature to 7.8 K at a current of 6.5 kA. In the present single-insert configuration of SULTAN a peak conductor field of 10.5 T was reached. >

Instrumentation and test of the Swiss LCT-coil

Just before Christmas 1983 the fabrication of the Swiss LCT-coil was finished. Tests at ambient temperature were performed on the factory site and after delivery in Oak Ridge. To avoid an undesirable delay of the rescheduled Partial-Array Test it was agreed to install The coil without its superconducting bus. In July 1984 the Swiss LCT-coil was successfully cooled down to LHe temperature together with the other two fully installed coils. Besides the cooling system, the instrumentation, measured parameters of the coil and some preliminary results obtained during the ongoing Partial-Array Test are presented.

Preliminary test results of the Swiss LCT-coil

The Swiss (CH) LCT-coil is the contribution of Switzerland to the international Large Coil Task (LCT) at Oak Ridge National Laboratory (ORNL) in Tennessee, USA. After delivery in February 1984, the CH coil was tested only cryogenically during the Partial-Array Test in the summer of the same year. The first opportunity to energize the CH coil arose during the on-going Six-Coil Test. The cooldown started on January 18, and all coils became superconducting on February 18, 1986. Checking the sensors of the CH coil and remeasuring of its cryogenic parameters began on March 25. Subsequently, the coil was energized up to its full nominal current of 13 kA, creating thereby a self-field of 6.4 T on the conductor. This test period ended on April 16 with experiments simulating the nuclear heating present in a fusion reactor as additional load on the winding. This paper presents the data taken during the cooldown and the successful single-coil test. The cooldown data and the cryogenic parameters of the coil are compared to the results of the Partial-Array Test. The interpretation of the data taken while the coil was energized as a single coil is preliminary and will be further investigated.

Testing of full size high current superconductors in SULTAN III

The high field test facility SULTAN III in operation at PSI/Switzerland tests full size industrial prototype superconductors for fusion applications such as ITER. The facility provides a background field of up to 11 T over a length of 58 cm. A 50 kA superconducting transformer works as a very low noise current source which allows a criterion of 0.1 /spl mu/V/cm to determine the superconducting to normal transition. Three 3.6 m long cable-in-conduit conductors based on both NbTi and Nb/sub 3/Sn, developed by different manufacturers, suitable for the central solenoid and toroidal field coils of ITER, have been tested so far. This paper presents the results of extensive measurements of critical current and current sharing temperature of the Nb/sub 3/Sn conductors in the 8-11 T range for temperatures between 4.5 K and 11 K. Voltage versus current curves have been analyzed with respect to the n value. The manufacturing of a high quality joint between two Nb/sub 3/Sn conductors after heat treatment is reported, together with some measurements of the joint resistance. >

Discharge performance analysis of the Swiss superconductive magnetic energy storage model

The study of a 50-kWh Swiss superconductive magnetic energy storage model is in progress to demonstrate the feasibility of a 1-MWh prototype concept. A preliminary discharge performance analysis of this model has shown that, assuming a rectangular pulse at full power (1 MW for 154 s), the total heat load due to AC losses in the complete coil is 90 W. Following a single discharge pulse, the maximum conductor temperature is 5.3 K at the outlet of the 1035 m long hydraulic channel (0.6 K due to AC losses, 0.3 K due to throttling). A continuous coil operation may be performed with dead times between pulses >or=7-20 min., depending on the effective temperature margin. >