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Long-term stability of metal-envelope enclosed ionization gauges

Published

Author(s)

James A. Fedchak, Dana R. Defibaugh

Abstract

Ionization vacuum gauges are used as secondary standards by calibration laboratories and as transfer standards in intercomparisons among metrology laboratories. A quantitative measurement of gauge stability with respect to the gauge calibration factor is critical for these applications. We report the long-term calibration stability of hot-filament metal-envelope enclosed ionization gauges based upon the analysis of repeat calibrations of nine gauges over a 15 year period. All of the gauges included in the study were of the same type: Bayard-Alpert type ionization gauges of an all-metal construction with an integral metal-envelope surrounding the hot-filament, grid, and collector. All were calibrated repeatedly at the National Institute of Standards and Technology (NIST) using the NIST high-vacuum standard, but are owned by organizations external to NIST. The gauges were removed from the high-vacuum standard after calibration, shipped back to the gauge-owner, and were returned to NIST at a later date (more than 1 year) for re-calibration. Gauge stability was determined using a pooled standard deviation (weighted root-mean-square average of individual gauge standard deviations) based on all calibration factors measured at NIST and was used to define the relative uncertainty component associated with long-term stability uLTS. We determined uLTS = 1.9 % (k = 1) for gauges operated with 4 mA of emission current, and uLTS = 2.8 % for gauges operated with 0.1 mA emission current.
Citation
Journal of Vacuum Science and Technology A
Volume
45
Issue
10

Keywords

ionization gauge, calibration, stability, vacuum measurement, ion-gauge pumping speed

Citation

Fedchak, J. and Defibaugh, D. (2012), Long-term stability of metal-envelope enclosed ionization gauges, Journal of Vacuum Science and Technology A, [online], https://doi.org/10.1116/1.4750482 (Accessed April 20, 2024)
Created December 1, 2012, Updated July 24, 2019