Energy pulses required to quench potted superconducting magnets at constant field

Epoxy impregnated superconducting magnets can be subjected to energy inputs from external sources or from stored energy released in the coil composite. If the energy released is sufficiently large, the temperature will rise locally driving the conductor normal causing a magnet quench. Several superconducting coils were constructed to determine the magnitude and size of disturbances required to cause a quench. These coils were wound from multifilament NbTi conductor, then impregnated with epoxy which was fiberglass reinforced. Small electrical heaters of various sizes were embedded in the coils to initiate a normal zone. These coils were placed in a background magnetic field ranging from 0 to 5.5 T and the energy required to cause a quench was determined as a function of the ratio of operating current to critical current at a constant field. The different size heaters allowed the energy to be distributed over various conductor volumes and the effects of the energy spatial distribution was determined.