Test of 60 kA coated conductor cable prototypes for fusion magnets

Abstract

Coated conductors could be promising materials for the fabrication of the large magnet systems of future fusion devices. Two prototype conductors (flat cables in steel conduits), each about 2 m long, were manufactured using coated conductor tapes (4 mm wide) from Super Power and SuperOx, with a total tape length of 1.6 km. Each flat cable is assembled from 20 strands, each strand consisting of a stack of 16 tapes surrounded by two half circular copper profiles, twisted and soldered. The tapes were measured at 12 T and 4.2 K and the results of the measurements were used for the assessment of the conductor electromagnetic properties at low temperature and high field. The two conductors were assembled together in a sample that was tested in the European Dipole (EDIPO) facility. The current sharing temperatures of the two conductors were measured at background fields from 8 T up to 12 T and for currents from 30 kA up to 70 kA: the measured values are within a few percent of the values expected from the measurements on tapes (short samples). After electromagnetic cycling, T cs at 12 T and 50 kA decreased from about 12 K to 11 K (about 10%), corresponding to less than 3% of I c .

Design of the HTS Fusion Conductors for TF and CS Coils

“…The difference between the T cs values defined at these criteria depends on the m-value of the T − E transition. In accordance with the test results of the HTS cable prototype [3], this difference can be estimated as ≈2 K at 12 T and for operating currents between 50 kA to 60 kA.…”

“…The critical current of the cable I c is affected by the self-field effect even at high background magnetic fields, but this effect is almost completely compensated by the angular dependence of the tape's critical current I t c at least in the operating conditions from 40 kA to 70 kA and from 8 T to 12 T [3]. Eventually, a simple and reliable approach to estimate I c is to sum up I t c corresponding to the perpendicular field component.…”

“…This is a direct consequence of the much weaker temperature dependence of the critical current of ReBCO materials compared to LTS (see detailed discussion in [3]). As a result, the HTS cables would require about half the amount of superconductors than LTS ones with the same T cs .…”

“…In June 2015 the sample was tested in the EDIPO test facility at SPC, including I c , T cs , AC loss and cycling measurements. The details of the manufacturing process and test results will be published in [3]. Comparing the assessed and measured DC performance of the cables, the tape transport properties were fully retained in the prototypes.…”

Numerical Simulation of a No-Insulation BSCCO Toroidal Magnet Applied in Magnetic Confinement Fusion

“…With the development in the properties of high temperature superconducting (HTS) conductors, the HTS magnet could be considered as potential Tokamak magnet components with the advantages of higher operation temperature and critical current density [1][2][3]. At present, the application of HTS in fusion devices mainly focuses on the design and fabrication of high temperature superconducting high current conductor [4][5][6][7][8], the design and fabrication of high temperature superconducting current lead [9,10], and the concept design and small model fabrication of HTS magnet [11,12]. It was revealed that when the TF coil system operates at the temperature range of 10 to 20 K, accordingly, the manufacturing and operating cost of the device could be reduced [13].…”