System przekazywania jednostki rezystancji od wzorca pierwotnego QHR do wzorców 100 TΩ oparty na transferach Hamona

Przedstawiono ideę systemu przekazywania jednostki rezystancji od wzorca pierwotnego QHR (Quantum Hall Resistance) do wzorców o dużych wartościach rezystancji, aż do 100 TΩ. W zakresie do 100 kΩ system ten bazuje na komparatorze kriogenicznym, a od 100 kΩ na transferach Hamona. Transfery te umożliwiają bardzo dokładne porównanie wartości rezystancji wzorców w stosunku 1:10 i 1:100. Opisano specjalnie wykonane dla tego systemu prototypowe transfery Hamona i ich zastosowanie w systemie.

An idea of a system for resistance unit transfer from QHR (Quantum Hall Resistance) to high value resistance standards up to 100 TΩ is presented in the paper. Below 100 kΩ this system is based on a cryogenic current comparator, and above 100 kΩ on Hamon transfers. Hamon transfers allow very accurate comparison of standards resistance values in ratios 1:10 and 1:100. Prototypes of Hamon transfers specially made for this system are described. The factors influencing accuracy of the Hamon transfers are presented. The most important of them are: insulation leakage, temperature variation of resistor surroundings, voltage variation, humidity of surrounding air, charge building in the insulation and highest value resistors. The methods for minimisation of influence of those factors are described. The construction solutions to minimise the leakage current and temperature variation are discussed in details. To minimise the leakage current, double insulation and shield potential rising have been used, while to minimise the temperature variation, internal termostatisation with Peltier elements placed on the boxes of Hamon transfers has been used.