Accession Number : AD0863804

Title :   The Influence of the Collimating Orifice on Knudsen Triple-Cell Effusion.

Descriptive Note : Technical rept. Jul 68-May 69,

Corporate Author : AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Bidwell, Lawrence R.

Report Date : OCT 1969

Pagination or Media Count : 28

Abstract : A quantitative theory for vapor effusion from Knudsen triple-cells has been developed. These cells, when used in conjunction with a mass spectrometer, permit a direct determination of the thermodynamic activity of a binary alloy component. In conventional Knudsen effussion studies, the vapor pressure of an element in an alloy and in the pure state are determined in separate experiments and their ratio is used to compute the activity. Because of the exponential relationship between vapor pressure and temperature, even small errors in temperature reproducibility result in large errors in the calculated activities. The Knudsen triple-cell avoids these errors but is subject to other limitations that are discussed. (Author)

Descriptors :   (*PYROMETALLURGY, MEASURING INSTRUMENTS), (*ALLOYS, THERMODYNAMICS), (*MEASURING INSTRUMENTS, GAS ANALYSIS), ORIFICES, COLLIMATORS, KINETIC THEORY, GAS FLOW, FLOW VISUALIZATION, THEORY, VAPOR PRESSURE.

Subject Categories : Properties of Metals and Alloys
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE