Development and application of diagnostic instrumentation for measurement of electron density and conductivity. Final technical progress report

摘要

The purpose of this contract was to assemble and demonstrate in the laboratory a Faraday rotation system for measurement of electron density and conductivity, with the intent to produce a system suitable for diagnostic support of the development of pulsed, space-based magnetohydrodynamic (MHD) power systems. Two system configurations were tested: (1) a rotating polarizer and (2) a beam splitting polarizer. Due to the short path length plasma produced in the laboratory flame, the long wavelength 496 (mu)m methyl fluoride laser line was used and only the more sensitive rotating polarizer configuration was used for the demonstration experiments. Electron number densities from 2 (times) 10(sup 19) to 9 (times) 10(sup 19) were measured with good agreement to statistical equilibrium (Saha) calculations using emission absorption-measured flame temperatures and neutral seed atom number seed atom nuclear densities. The electron collision frequencies were measured by transmission measurements. Combining these two measurements gave measured electron conductivities of between 4 and 12 mohs/m. These results compared reasonably well with those found with an electron collision frequency model combined with chemical equilibrium calculations and the emission absorption measurements. Ellipticity measurements of electron collision frequency were not possible due to the short path length of the laboratory plasma. 46 refs., 25 figs., 9 tabs.