Energy Released by Flux Jumps in Superconductors

Abstract

The energy released during a flux jump in single‐core Nb–Ti wires and multifilament composite Nb–Ti superconductors has been measured. The evaporation of liquid helium produced by the flux jump was indirectly measured and for calibration was compared with that produced by a known energy input generated by a current pulse through a heater wire. The experiment has demonstrated that the equation derived for a slab geometry, relating the magnetization energy to the initial and final value of magnetization, is also valid for the wire samples, and (indirectly) for composite superconductors. For the composite superconductors with nontwisted filaments, the experiment has also shown that the configuration of filaments rather than their number or size is the principle determinant of the magnetization and thus the energy. The experiment further confirms that twisting the filaments along the axis increases the stability of composite superconductors.