Accession Number : AD0427830

Title :   EFFECTS OF ELECTRON-SURFACE INTERACTION IN IONIZATION GAUGES,

Corporate Author : ILLINOIS UNIV URBANA COORDINATED SCIENCE LAB

Personal Author(s) : SCHUEMANN,W. C. ; DE Segovia,J. L. ; Alpert,D.

Report Date : AUG 1963

Pagination or Media Count : 18

Abstract : A systematic study of an anomalous nonlinearity in ionization gauges was made, indicating the magnitude of possible errors in ionization gauge readings. The errors are particulary enhanced after O2 has been introduced into the system. Evidence was provided for interpreting the effect as due to dissociative ionization by electron impact at the grid surface. At low values of grid current, there is an enhanced rate of production of such ions accompanied by a reduced rate of collection in a Bayard-Alpert gauge. The anomalous readings in ionization gauges can be reduced greatly by thorough outgassing of the grid by electron bombardment. Thereafter, operation at electron currents of 5 ma or greater gives reliable readings. In the presence of O2 a number of other effects may be present to give erroneous ionization gauge readings; in particular, composition of the gas may be altered, both by chemical reactions at the hot filamant and by electron bombardment of adsorbed gases. (Author)

Descriptors :   (*IONIZATION GAGES, NONLINEAR SYSTEMS), ERRORS, OXYGEN, ELECTRON IRRADIATION, IONS, GAS ANALYSIS, MEASUREMENT

Distribution Statement : APPROVED FOR PUBLIC RELEASE