Josephson Spaenningsreferens (Josephson Voltage Standard)

摘要

The traceability of the Swedish unit for electromotive force is now maintained by the Josephson effect. The measurements are made by a single Josephson junction generating approximately 2 mV. The comparison of the 1 V level is made by means of a cryogenic voltage divider, a cryogenic current comparator and a squid. The total uncertainty is within + or - 0.1 microV (2 sigma). The Josephson standard was constructed at the Technical Research Centre of Finland (VTT) in a project partly financed by Nordisk Industrifond. Identical units were made for each of the national laboratories in Denmark, Norway and Sweden. The Swedish Josephson standard, with some changes of the original construction, is described. The results of measurements on the Swedish primary group of Weston cells are presented.