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The results of microwave attenuation, phase shift and radiation temperature measurements in the late afterglows of pulsed oxygen discharges of various types are discussed from the point of view of the collision frequency and G-factor determination. A new general theory for the evaluation of the G- factor from the radiation temperature increases under microwave heating conditions is reported. The values computed with this theory in nitrogen are in very good agreement with the previous diffusion measurements by Crompton and Sutton, whereas in oxygen the agreement with the measurements by Healey and Kirkpatrick is much less satisfactory.

The propagation characteristics of a uniform magnets-ionic duct of circular cross-section are determined for frequencies higher than the cyclotron frequency - The ratios: plasma wavelength/free space wavelength and power flowing in the plasma/power flowing outside are evaluated and discussed as a function of the diameter/wavelength ratio and of the plasma permittivity for the propagation of circularly symmetrical modes. The Brillouin diagrams for frequencies higher and lower than the cyclotron frequency are also derived.

Two hypothesis, ionization from metastables and shock waves, were proposed in order to explain the high electron temperature in the afterglow of a dc Nitrogen discharge. Some experiments were performed to sustain or reject these hypothesis. The electron fractional energy loss per collision was also measured and found in good agreement with previous measurements by Crompton and Sutton (Proc. Roy Soc. (London), A215:467, 1952). (Author)