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JOSEPHSON-VOLTAGE STANDARD IN A WORKING CALIBRATION LABORATORY Karl-Peter Lallmann Fluke Deutschland GmbH Heinrich-Hertz-Strasse 11 34123 Kassel / Germany Phone:++49 561 9594 651 Fax: ++49 561 9594 609 E-mail: [email protected] Abstract One might ask if it is really necessary to use a Josephson Voltage Standard in an accredited calibration laboratory. Yes, there are circumstances that make the use of such a standard necessary. With the evolvement of dc reference standards and calibrators towards very small specifications on Direct Voltage it becomes a good tool to bring measurement uncertainties to a level with which these instruments can be checked to be within specifications. This papers describes the use of a Josephson Voltage Standard in an accredited calibration laboratory operated by Fluke Germany Introduction Josephson-Voltage Standards are widely used in National Institutes for their work in metrology and scientific research. However, there are several companies and other institutes in the United States of America that have established such systems, but none of them are used in a Customer Support environment or accredited laboratory. We saw the requirement of a Josephson-Voltage Standard coming with the evolvement of calibrators and dc reference standards designed and produced by Fluke Corporation Everett/USA. The requirement to service and calibrate these instruments for Fluke in Europe, made it necessary to develop and find new ways for low measurement uncertainties required to calibrate and verify the specifications of these instruments. The only way this could be accomplished was with the use of a Josephson Voltage Standard. However, there are some aspects that need to be defined before such an investment may be done. Cost of purchase and operating costs were the most significant, but after looking at them very closely it became obvious that it will be paid back in the long term. The Josephson Voltage Standard The Josephson effect is a super conducting physical phenomenon that relates voltage to frequency through the ratio of fundamental constants. A Josephson array, using an integrated circuit containing a number of Josephson junctions, i is an intrinsic, independently reproducible standard that is used to represent rather than realize the SI volt. The output of a sin