Status Report to CCEM of Electrical Metrology Developments at NIST

NIST researchers advanced the measurement and automation capabilities of quantum-based dc and ac programmable Josephson voltage standards (PJVS) such that the NIST PJVS is now capable of providing ac voltage measurements through differential sampling at voltages up to 10 V and frequencies up to 400 kHz. New automation software and hardware were implemented. Measurements of leakage resistance were performed and optimized (in collaboration with Solve at BIPM). Two cryocooled PJVS systems were also developed and demonstrated, and their performance was characterized. All results were presented at the CPEM 2014 conference and at the 2014 Applied Superconductivity Conference, and published in Metrologia, IEEE Trans. Inst. Meas. and IEEE Trans. Appl. Superconduct. NIST upgraded existing systems for collaborators at NASA Kennedy Space Center, INMETRO (Brazil), ITRI (Taiwan), NPL (India), KRISS (S. Korea), and CENAM (Mexico). We installed three 10V PJVS systems at NIM (China), two of which will be used with the impedance balance system, a portable version at BIPM, and a partial system at MRL (New Zealand), which MRL customized to operate in a reliquifier-compatible cryostat for use in voltage metrology and with their piston-balance measurement system. The NIST systems are constructed primarily from commercially available electronics, which greatly enhances their reliability. As of August 2014, NIST is providing duplicate versions of both the liquid-helium-cooled and cryocooled PJVS systems through a new NIST Standard Reference Instrument program that is similar to the SRM program.