This proposal aims to develop theories for a better understanding of the observational results of the ionospheric HF heating experiments, and thus for leading a better planning of future heating experiments. The work will focus on: (1) the role of secondary parametric instability processes together with nonlinear scattering processes on the generation of secondary stimulated EM emissions (SEEs), (2) generation of ELF/VLF waves by thermal instabilities excited in heater-modulated electrojet, (3) new spectral features of plasma lines enhanced by obliquely incident HF heater, and (4) physical process responsible for the generation of energetic electrons in the context of weak turbulence theory.***
