Operation of compact cryocooled 2V programmable josephson voltage standard at NIM

Abstract

In the past, most of worldwide Josephson voltage standard systems use liquid helium to cool down the Josephson junction chips. Due to the liquid helium shortage, the cost of operating liquid helium based Josephson voltage standards rises year by year. Therefore there is an increasing need for a compact cryocoooled Josephson voltage standard which has no need of liquid helium. This paper presents a domestic liquid-helium-free dc programmable Josephson voltage standard (PJVS) operating on a cryocooler at 4K or 10 K. In this work, the performance of a NIST-fabricated two volt Josephson junction array (JJA) and a NMIJ-fabricated two volt JJA operating in a cryopackage around the Gifford-McMahon (GM) cryocooler is presented. The JJA chip has been shown to operate successfully with the domestic cryopakage. Stable quantum steps with operating margin greater than 1.4 mA was obtained. Differences in behavior of the NIST-fabricated JJA in liquid helium and on the cryocooler are also discussed.