CHARACTERISTICS OF METAL VAPOR.
Final scientific rept., 15 May 63-3 Oct 65,
LITTLE (ARTHUR D) INC CAMBRIDGE MASS
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The objectives were to examine the radiation attenuation properties of alkali metal vapors and their effects on the radiation heat transfer characteristics of arc and plasma systems. An absorption cell used to measure the transmittance of sodium, potassium and cesium vapor over the temperature range from 300 to 900K with alkali partial pressures of 0.001 to 40 torr is described. A grating spectrometer was used with the cell to obtain data over the wave length region from 0.2 to 1.0 micron. Strong widespread absorption in the visible and near infrared regions caused by band absorption of the alkali metal molecules and absorption in narrow regions surrounding the first principal series lines of the alkali metal atoms were noted. Molecular absorption cross section values, calculated from plots of transmittance versus the effective vapor path length in the absorption cell, varied from 0.1 to 30 sq Angstrom units, depending upon the alkali metal type and the wave length. The molecular cross sections for cesium were larger than for potassium sodium had the smallest cross section. Effective atomic absorption cross sections were calculated in the regions where atomic absorption was dominant. Sample calculations based upon the measured cross sections indicated that up to 30 of the radiation emitted by a source at 10,000K could be absorbed in a 2.5 - cm layer of alkali metal vapor cesium in equilibrium at 400C. Author
- Plasma Physics and Magnetohydrodynamics