OPTICAL METHODS OF MEASURING PLASMA JET TEMPERATURES. PART II. MEASUREMENT BY PHOTOELECTRIC PYROMETRY
Abstract
The application of two-path optical pyrometry to measurement of plasma jet temperature was studied from both theoretical and practical aspects. A pyrometer was constructed with its detection system consisting of a selected 1P21 photomultiplier associated with an electronic filter tuned to 1 c. Comparison between the unknown source and a calibrated filament is made at this frequency which is chosen to give optimum signal-to-noise ratio. The transparency of high temperature plasma necessitates the use of an opacifier if the two-path technique is to be employed with any accuracy. The use of sodium as a non-grey temperature indicating probe was investigated. The measurememt of integral radiancy is made almost monochromatic by passage through a narrow cut interference filter centered on 5892 angstroms, having a halfwidth of 7.5 angstroms. This enables the sodium D line doublet to be selected uniquely but renders the Beer's law expression inapplicable unless the shape of the emission line is known. The theories of spectral line broadening suggested the use of a theory by Lindholm to give this data and it was applied to the interpretation of the pyrometer readings. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1962
- Accession Number
- AD0275490
Entities
People
- G.c. Williams
- H.c. Hottel
Organizations
- Massachusetts Institute of Technology