CRYOCOOLED PRIMARY VOLTAGE STANDARD SYSTEM

The primary voltage standard system based on the Josephson junction ar ray (JJA) produces the ultimate in accuracy for de voltage calibration , Hen-ever, it is only used in the highest le, el standards laboratori es due to the expense and inconvenience of liquid helium cooling, In c ooperation with the US Army Research Laboratory, HYPRES has developed a mobile JJA primary voltage standard system using a closed cycle refr igerator (CCR), The system performance is comparable to a conventional liquid helium system, The elimination of liquid helium makes the mobi le system not only more economically attractive, but also more conveni ent to use, The mobile JJA voltage standard system is very suitable fo r users who lack access to liquid helium, and for those who require tr ansportability.