Establishment of Josephson array voltage standard system at KSRI

A Josephson array voltage standard system that is used to maintain the national standard of voltage in Korea according to the CIPM recommendation is described. The standard, which consists of a microwave source, electronics, and a cryogenic unit was constructed using a 2076-junction array. Measurement shows that the mean value of EMF of the primary standard cell group differs from the expected value by 9.8 p.p.m. if the new Josephson constant, K/sub J-90/ =483597.9 GHz/V, is used to calculate the array voltage. The difference originates mainly from the use of a different value of K/sub J/, and the resultant change of EMF of the cells is less than 0.6 p.p.m. in ten years.<>