IMPROVEMENTS IN RESISTANCE SCALING AT NIST USING CRYOGENIC CURRENT COMPARTORS

Cryogenic current comparators (CCC's) are being used at NIST to verify Hamon-type resistance scaling techniques from 1 to 100 OMEGA, 1 kOMEG A, 6453.20 OMEGA, and 10 kOMEGA. Measurements comparing the 10/1, 64.5 32/1, and 100/1 ratios of CCC's to that of Hamon transfer ratios agree to = 0.01 ppm, the practical limit of accuracy using Hamon transfer s tandards with conventional resistance bridges. The higher ratio accura cies and sensitivities of CCC bridges will make it possible to lower t he uncertainties associated with resistance scaling at NIST significan tly.