Title :
Alignment uncertainties of the NIST watt experiment
Author :
Gillespie, Aaron D. ; Fujii, Ken-ichi ; Newell, David B. ; Olsen, Paul T. ; Picard, A. ; Steiner, Richard L. ; Stenbakken, Gerard N. ; Williams, Edwin R.
Author_Institution :
Electr. Div., Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA
fDate :
4/1/1997 12:00:00 AM
Abstract :
The effects of alignment uncertainties of the NIST watt balance with respect to local gravity and the magnetic flux density of the balance have been analyzed. Techniques for measuring all quantities relevant to misalignment have been developed. The components of the relative combined standard uncertainty of the measured value of the watt due to alignment uncertainties have been reduced to 20 nW/W, and potential improvements in the balance design have been identified which could ultimately lead to a reduction of that uncertainty to below 10 nW/W
Keywords :
balances; light interferometry; measurement errors; measurement standards; position control; power measurement; units (measurement); NIST watt experiment; alignment uncertainties; balance design improvement; laser interferometers; local gravity; magnetic flux density; misalignment; relative combined standard uncertainty; Angular velocity; Electric variables measurement; Force measurement; Magnetic flux density; Mechanical variables measurement; NIST; Superconducting coils; Uncertainty; Velocity measurement; Voltage;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
