Langmuir waves in non-uniformly heated magnetoplasma

The propagation of Langmuir waves in the vicinity of the upper hybrid reson ance in an inhomogeneously heated magnetoplasma is studied by means of exac t analytical solutions. These are obtained through special transformations of the dispersive equations for the waves. These exact solutions are indepe ndent of WKB approximations for the wide classes of monotonic and non-monot onic spatial profiles of electron temperature. Thermal acceleration and ret ardation of Langmuir waves which depends on the shapes of these profiles is studied. The possibility of formation of a waveguide for Langmuir waves, c aused by an inhomogeneous temperature distribution is demonstrated and the spectrum of trapped modes in such a thermal waveguide is presented.