TITLE:
Cryocooler Operation of a Pulse-Driven AC Josephson Voltage Standard at PTB
AUTHORS:
Oliver F. O. Kieler, Thomas Scheller, Johannes Kohlmann
KEYWORDS:
Josephson Voltage Standard; Josephson Arbitrary Waveform Synthesizer (JAWS); SNS Josephson Junction; Cryocooler; Helium-Free Setup
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.3 No.4,
November
4,
2013
ABSTRACT: The PTB Josephson Arbitrary Waveform Synthesizer (JAWS) enables the generation of arbitrary waveforms up to voltages of 70 mVRMS (199 mVPP) using two Josephson arrays in series containing 4000 Josephson junctions each. The SNS-like double-stacked junctions are based on NbxSi1-x as barrier material. While the JAWS system is typically operated using a Dewar with liquid helium, the operation in a closed-cycle pulse-tube cryocooler at temperatures around 4.2 K range was here investigated and successfully demonstrated. For this purpose a special designed cryoprobe was used to provide high quality pulses to the Josephson arrays.