NIST 10 V Programmable Josephson Voltage Standard System Using a Low Capacity Cryocooler
Logan A. Howe, Anna Fox, Alain Rufenacht, Charles J. Burroughs, Paul Dresselhaus, Samuel Benz, Robert E. Schwall
Rising costs of and difficulty in obtaining liquid helium in many areas of the world provides strong motivation for cryogen-free operation of superconducting devices such as NIST Programmable Josephson Voltage Standard (PJVS) systems. However, operation on closed-cycle cryocoolers must not compromise the stability and accuracy of the quantized voltage steps. Here we present new cryogenic packaging and cryostat integration that has been optimized for the NIST 10 V PJVS superconducting integrated circuits, demonstrating improved attenuation of coldhead temperature oscillations, and optimization of all thermal conductances in the junction-to-coldhead path. When combined with an improved design of 10 V PJVS devices employing Nb/NbxSi1-x/Nb junctions with increased operating margins, we have operated a NIST PJVS at 10 V with over 1.32 mA current margins on a nominal 100 mW cryocooler using a 3.0 kW water-cooled compressor. The new cryo-package, in conjunction with the improved generation of chips, completely eliminates the need for liquid cryogens in applications using NIST 10 V PJVS systems.
, Fox, A.
, Rufenacht, A.
, Burroughs, C.
, Dresselhaus, P.
, Benz, S.
and Schwall, R.
NIST 10 V Programmable Josephson Voltage Standard System Using a Low Capacity Cryocooler, IEEE Transactions on Applied Superconductivity, [online], https://doi.org/10.1109/TASC.2014.2367531
(Accessed December 8, 2023)