Polarization properties of the third harmonic of a pumping field that is generated in plasmas created by the ionization of excited hydrogen-like atoms

A theory of the polarization properties of the radiation harmonics, which are generated by a monochromatic pumping field in the plasma of hydrogen-like ions, is constructed. Taking the generation of the third harmonic as an example, we analyze the properties of a degree of its circular polarization as a function of both the intensity of a pumping electric field and a degree of the circular polarization of the field. The threshold character of the bifurcation of a position of the complete circular polarization of the third harmonic is established, and the dependence of the polarization properties of this harmonic on the principal quantum number of excited states of electrons is described