Cryogen Free JJ Volt System

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...