Development of a liquid nitrogen pump using superconducting bulk motor

A magnetically levitated stepping motor using high T/sub c/ superconductor has been studied. The levitated stepping motor consists of a cylindrical rotor with superconductors and a stator with eight electromagnets. The rotor measures 10 mm in diameter, 46 mm in length, and 18 g in weight. The superconductors of the rotor are zero-field-cooled in liquid nitrogen. The levitated rotor is driven by four-phase excitations. The rotor is successfully applied to a liquid nitrogen pump. The dynamic properties of the nitrogen pump are discussed in this paper.