Accuracy of the new voltage standard using Josephson junctions cooled to 77 K

A practical dc voltage standard with output voltages Ł/hts from 0.1 V to 10 V using high temperature superconductor (HTS) arrays of Josephson junctions cooled to 77 K was characterized. HTS arrays with increased current margins and the voltage divider with a high stability of the divider's coefficients enable stable and reproducible automated calibration of the new HTS standard. The direct comparison of U
_HTS
against the voltage generated on an array of niobium Josephson junctions cooled to 4.2 K reveals the agreement of voltages at 1 V level with a Type A uncertainty equal to a few parts in 10
⁸
.