Investigation of wire motion in superconducting magnets

A technique was developed which allows the direct observation of the EMF induced by wire motion and the calculation of the energy release resulting from the motion. Measurements made on a superconducting quadrupole magnet showed that the excitation is accompanied by a great number of wire-motion events of a typical duration of 100 mu s and a typical energy release per unit cross section of 1 mJ/mm/sup 2/. A simple stability model based on the motion of a single strand over a half-twist pitch was then developed. The model could account for the order of magnitude of the energies involved.