VACUUM MEASUREMENTS BY TIME-OF-FLIGHT MASS SPECTROMETRY
Abstract
Procedures are discussed for using mass spectrometers to make absolute partial pressure measurements of complicated residual gas mixtures in high vacuum systems. The details of the matrix inversion technique and an interaction procedure for calculating partial pressures from mass spectrometer data are presented. Performance of a Bendix Model 17-210V time-of-flight mass spectrometer and calibration data obtained are given. These data indicate that short-term instrument stability cannot be assumed for mass spectrometers which use electron multipliers for ion detection, and that instrument linearity can be assumed only under certain operating conditions. The data show that frequent, in-place, mass spectrometer calibrations are necessary. The matrix inversion technique and the iteration procedure were evaluated experimentally by reducing the 17-210V spectrum of a 12-component mixture of common residual gases whose partial pressures were known. The experimental results indicate that the iteration technique is the simplest to apply, and that it produces more accurate partial pressure solutions. It is concluded that accuracies of plus or minus 15 percent in partial pressure measurements are obtainable. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1966
- Accession Number
- AD0800436
Entities
People
- A. J. Mathews
- F. G. Sherrell
Organizations
- Arnold Engineering Development Complex