Absorption and Dispersion of Microwaves in Flames

The dependence of the high-frequency electric conductivity and the optical constants of a weakly ionized gas on the microwave frequency, the electron-molecule collision frequency, the electron concentration, and an external magnetic field are discussed. Measurements of the electric conductivity between 23.10 and 92.96 kMc/sec indicate that the effective electron-molecule collision frequency in an acetylene-air flame is independent of the electron velocity within the limits of error. Cyclotron resonance of free electrons has been found in low-pressure flames at 24 kMc/sec. This effect can be used to determine both the concentration of free electrons and the electron collision frequency.