Cryo free JJ volt system

Tender description

The National Physical Laboratory (NPL) requirement is for a complete primary voltage calibration system built around a Josephson array quantum standard. The purpose is to move away from the current generation of standards that use liquid helium to cool the sample to one that is liquid cryogen-free with the aim that no liquid helium should be required for either cool-down or routine operation, and hence the system should be capable of continuous operation for periods of at least several months. The system should be capable of providing:  SI traceable DC voltages up to 10 V, with an uncertainty better than 1 nV/V.  software to run the system and automate the calibration of standards.  the capability to generate AC voltages up to a few kHz.