Traceability for Aerosol Electrometer in the fA Range
Dean G. Jarrett, Miles Owen
Described here are the configurations and procedures used to provide traceability to electrical standards for an aerosol electrometer calibration in the range ± 20 fA to ± 40 fA. The technique used here simulated the condition of a current induced when charged particles would flow into the aerosol electrometers Faraday-cup by replacing the charged particle flow with known source currents. The technique used here was to source known currents over a wider range of ± 1 pA in addition to the ± 20 fA to ± 40 fA and subtract the offset (i.e. zero) current measured when charged particles are not flowing into the aerosol electrometer. Linear regression was used to scale from the pA to fA range by determining the slope of the sourced vs. measured currents over both ranges and using the residuals to verify the linearity. Two independent methods, both traceable to electrical standards, were used to source known currents from ± 1 pA to ± 20 fA, a source-meter and a voltage-resistor source using high resistance standards of 100 GΩ or 1 TΩ.
Instrumentation Viewpoint Magazine ISSN:1886-4864
July 18-19, 2013
2013 IMEKO TC-4 Symposium, Measurements of Electrical Quantities
aerosol electrometer, standard resistor, current source, charged particles, Faraday cup