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 the quench 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.