Quench in High-Temperature Superconducting Motor Field Coils: Experimental Results at 30 K

The results of quench tests on high-temperature superconducting (HTS) motor coils conduction-cooled to 30 K are presented. In previous tests, the same coils were cooled by direct immersion in liquid nitrogen. In spite of both a significantly lower temperature and a different cooling mechanism, the 30 K tests confirm the previous results which showed that the quench process is characterized by a current level, referred to as thequench current, above which the cooling system cannot maintain the winding temperature. Currents in excess of this value will produce an unstable growth in winding temperature in a process commonly referred to as a coil quench.