Interaction of a Non-Uniform Plasma with Microwave Radiation

摘要

An investigation was made of the interaction of microwave radiation with a non-uniform plasma for both normal and non-normal incidence of the radiation. For the case of normal incidence the wave equation was solved by numerical integration. The results show that, for a large range of collision frequencies, a major fraction of the incident radiation is absorbed by the plasma except for very sharp density gradients. The reflection coefficient has been obtained for a large range of the governing parameters, i. e., electron density gradient, wavelength of the incident radiation, and collision frequency. For the case of non-normal incidence the radiation does not penetrate into the region of rapidly changing index of refraction so long as it is not too close to normal incidence. The ray path has therefore been calculated by geometrical optics and the absorption within the plasma has been obtained by the WKB method. Because of the greater complexity of the problem for the non-normal case, the calculations have been restricted to the short wavelength region. The results show that the absorption coefficient varies very little and remains large over a wide range of angles of incidence, but drops off rapidly beyond 45 degrees. (Author)