Loss measurements on superconducting Nb by a cryogenic dual compensated calorimeter for the implementation of the kilogram standard by the levitation mass method

摘要

A cryogenic dual compensated calorimeter was constructed for energy loss measurements in superconducting materials. The losses induced by slowly varying periodic magnetic fields (amplitudes < 50 mT) in field-generating coils fabricated from different niobium wires were at the level of 500 nJ/cycle. Measurable losses are caused by incomplete Meissner effect in tested superconducting materials. The results of the study show the difficulties and limitations in the implementation of the kilogram standard using the 'superconducting magnetic levitation mass' method.