National Physical Laboratory

Two papers published on cryogenic current comparators

Jonathan Williams has had two papers published this month. The first, 'Cryogenic current comparators and their application to electrical metrology', reviews a key component in electrical metrology, the cryogenic current comparator (CCC). This device uses a superconducting shield to maintain very high ratio accuracy when electrical units are scaled over decade values, and has been successfully used to verify the accuracy of electrical quantum effects such as the quantised Hall effect.

The second paper, 'Design Considerations for a CCC Bridge With Complete Digital Control', shows that the final performance of such a bridge is limited only by the accuracy of the current comparator, the noise sources associated with the voltage and current null detectors, and the resistors under test. The paper also explains how the effect of leakage resistance in the system can be minimised.

Last Updated: 9 Sep 2013
Created: 15 Dec 2011

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