Dry cooling of a 10 V programmable Josephson voltage standard array

This paper describes the properties of a 10 V programmable Josephson voltage standard (PJVS) array operated in a cryocooler. The operating margins at 70 GHz frequencies are discussed and compared to liquid helium cooling. A crucial factor is the limited heat conduction between PJVS chip and cold stage. A method is presented to estimate the heat conduction directly with the Josephson array. Finally, a direct comparison between two 10 V PJVS arrays, one operated in a cryocooler and the other cooled with liquid helium is performed and shows an agreement to a level of 1 part in 10 ⁁ {−10}.