Characterization of a laboratory scale high-Tc 'D-shaped' magnet

A 'D-shaped' laboratory scale magnet resembling the toroidal field magnet of a tokamak has been fabricated using technical grade BSCCO high-Tc superconductor tape. The I–V characteristic as a function of the current ramp rate, as well as the critical current behavior under low external transverse magnetic fields, has been experimentally investigated at liquid nitrogen temperature. Degradation up to 46% in the critical current of the magnet with respect to its virgin tape has been observed. Hysteresis behavior has also been observed during ramp-up and ramp-down. The normal zone propagation velocity for quenching the magnet has been obtained experimentally to be 2.5 cm s−1 for a transport current of 60 A at 80 K for the critical current of about 150 A. (paper)