Quench experiments on superconductive coils

A set of four similar superconductive coils of 166 mm inner winding diameter were wet-wound with NbTi wire for subsequent application in various configurations: one single coil, a pair of coils or all four coils stacked on top of each other and connected in series. The height of the winding was 41 mm and the thickness 9 mm. The detailed observation of the time-dependence of the current and voltage with a data processing system yielded information on the time scale of the quench propagation. In the single coil and the pair of coils the time dependence of the quench resistance with time was derived from an analysis of the current and the coil voltages during the transient. With the four coils the time required for the current to decrease from 90 % to 10 % gets shorter with increasing quench current. Variations of 1.6 s to 0.3 s were observed in this configuration. At the maximum current a magnetic induction of at least 2.5 T was reached in a volume of over 2.5 litres. The self-inductance of this system was 1.28 Henry and the stored energy attained 22 kJ.