Determination of electron density and collision frequency in a gaseous discharge by microwave propagation measurements

From measurements of absorption and phase shift of microwaves passing through a discharge, several wavelengths long, in a waveguide the electron densities and collision frequencies may be deduced if at least two frequencies are used. Results are quoted for argon discharges at 0.5 and 2 mm Hg pressure and for 2-16 mA current. The electron densities, nearly the same at 8500 and 12 000 Mc/s, varied from 1 to 15times109/ml.