Comparison of two ICCS conductors for MHD application

Two subscale, internally cooled, cabled superconductors (ICCSs) have been examined as candidates for use in a retrofit MHD (magnetohydrodynamic) topping cycle magnet. One of these was a 3*3*3 cable in which all the strands were multifilamentary NbTi stabilized with copper. The other was a 3*3*3 cable in which two strands in each of the nine triplets wa OFHC copper and one was multifilamentary NbTi. The overall copper-to-superconductor ratio for each of the two 27-strand cables was approximately the same. The two conductors were cowound onto a grooved mandrel in such a way that they could be tested alternately. Each sample was instrumented with a heater at the center of the conductor length and with a pressure transducer, four pairs of voltage taps, and one iron-doped gold/constantan thermocouple. Performance tests of the conductors were made at 6-, 7-, and 7.8-T background magnetic fields and at heater input energies ranging from 60 mJ/cm/sup 3/ to 1758 mJ/cm/sup 3/ of conductor. The results of these tests and their significance for MHD magnet design and economics are discussed.<>