Cryogen-Free Operation of 10 V Programmable Josephson Voltage Standards

Given the recent shortages of liquid helium, cryogen-free operation of superconducting devices, such as programmable Josephson voltage standard (PJVS) systems, has become preferable worldwide, and a necessity in some locations. However, reliable operation on a cryocooler is heavily dependent on the...

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Bibliographic Details
Published in:IEEE transactions on applied superconductivity 2013-06, Vol.23 (3), p.1300605-1300605
Main Authors: Howe, L., Burroughs, C. J., Dresselhaus, P. D., Benz, S. P., Schwall, R. E.
Format: Article
Language:English
Subjects:
Applied sciences
Chips
Design. Technologies. Operation analysis. Testing
Electric potential
Electromagnetic heating
Electronic equipment and fabrication. Passive components, printed wiring boards, connectics
Electronics
Exact sciences and technology
Integrated circuits
Josephson arrays
Junctions
Liquid helium
Microwave filters
Niobium
NIST
Oscillations
primary standards
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Studies
superconducting device packaging
Superconducting devices
Superconductivity
Temperature
thermal conductance
Thermal conductivity
Voltage
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Summary:Given the recent shortages of liquid helium, cryogen-free operation of superconducting devices, such as programmable Josephson voltage standard (PJVS) systems, has become preferable worldwide, and a necessity in some locations. However, reliable operation on a cryocooler is heavily dependent on the ability to create a constant temperature that is low enough to allow the PJVS junctions to operate uniformly. In this work, we systematically investigated as a function of temperature the performance of NIST 10 V PJVS chips employing \hbox{Nb/Nb}_{x}\hbox{Si}_{1-x}/\hbox{Nb} superconducting junctions. Additionally, we addressed the major factors limiting the performance of a cryocooled PJVS: adequate attenuation of the coldhead temperature oscillations and the minimization thermal gradients between the chip and the cryocooler. Through the development of a robust and reproducible method for soldering chips to a Cu carrier (package), we increased the thermal conductances within the packaging to their practical maximum values. This, in addition to the incorporation of a passive two-stage thermal filter, allows us to confidently predict that the required cooling power for the successful cryogen-free operation of the NIST 10 V PJVS is \sim 0.5 W at 4 K.
ISSN:1051-8223
1558-2515
DOI:10.1109/TASC.2012.2230052