The portable Josephson Voltage Standard, a new compact, fully automated calibration system for DC reference standards and digital voltmeters, was developed over the past three years by Sandia in cooperation with the National Institute of Standards and Technology (NIST) in Boulder, Colo. Sandian Stuart Kupferman (1542) provided consulting and acted as a customer interface during development of the portable voltage standard, and Sandia's Primary Standards Laboratory evaluated and certified the portable unit against current state-of-the-art standards.
The Primary Standards Laboratory assures the accuracy of measurements for DOE by certifying standards, developing measurement techniques, and advancing the state of the art in metrology, the science that deals with measurement. Each year, the laboratory performs more than 2,000 certifications of top-level standards in more than 80 measurement areas covering three broad disciplines: physical, electrical, and radiation.
"This new portable standard is three times lighter and seven times smaller than laboratory systems," Stu says. "All of the system electronics are integrated into a single 13-centimeter-high, rack-width box that is controlled by a laptop computer."
The portable system also has proven to be just as accurate as the much larger laboratory voltage standard, featuring an accuracy of better than 0.02 parts per million.
A key component of the system is in the Josephson Array Chip produced by Hypres, Inc. of Elmsford, N.Y., which is interested in commercializing the portable Josephson Voltage Standard. The prototype is cooled by liquid helium with a 100-liter Dewar sufficient to operate the system for up to eight weeks.
Co-developer Clark Hamilton of NIST says the new portable standard successfully passed two field tests last year at the NASA White Sands Test Facility in Las Cruces and at the NASA Kennedy Space Center in Florida.
The training at Sandia in December consisted of three days of intensive hands-on work for technicians and engineers from the nine NASA laboratories. Hamilton says it was important to ensure that technicians, rather than only scientists and engineers, are able to operate and maintain the portable system.
"We needed this interface with the users to ensure proper functioning as a standard at the high level it will be used," Hamilton says. "But the most difficult test is still to come as we circulate the portable standard among nine different NASA labs and see that it functions properly within different conditions. If the users are enthusiastic about it, they will make this work."
The prototype system will rotate among nine NASA facilities over the coming year, spending about a month at each location. The system currently is at the Jet Propulsion Laboratory in Pasadena, Calif. Each lab will have to pay only the cost of shipping and enough liquid helium to keep it operational, or about $1,000, Hamilton says. - Chris Miller
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