1 V programmable josephson voltage standard and its applications at NIM

A new programmable Josephson voltage standard (PJVS) at 1 V level was developed at National Institute of Metrology (NIM), China. This system is able to generate dc voltage and stepwise-approximated ac voltage at frequencies up to 1 kHz. The relative uncertainty of Zener voltage reference calibration at the level of 1.018 V is better than 3×10^-9. The uncertainty of synthesized ac waveform is better than 1ppm. We have carried out some applications with the synthesized ac waveform, for instance, a new approach of magnetic flux measurement was proposed by measuring the flux difference between the rectangular pulses synthesized by the Josephson system and the flux under test. Furthermore, a new method was developed to precisely calibrate the Fluke 5720A calibrator, which measures the difference between the fundamental rms value of ac voltage offered by the Fluke 5720A and the stepwise-approximated ac voltage generated by the Josephson system via a Lock-in Aamplifier (LIA) as a null detector.