Some parametric instabilities of an ordinary electromagnetic wave in magnetized plasmas

Some of the parametric instabilities of an ordinary electromagnetic wave decaying into (i) a high-frequency upper hybrid wave and a low-frequency mixed-mode kinetic Alfvén wave and (ii) an obliquely propagating ordinary scattered electromagnetic wave and a low-frequency electrostatic-ion Bernstein wave (stimulated Brillouin scattering) have been investigated. In channel (i), the partially electrostatic nature of the kinetic Alfvén wave and the component of the low-frequency ponderomotive force along the direction of the external magnetic field lead to the dominant coupling. Explicit expressions for the growth rate and threshold power are given. It is found that, in the case of channel (ii), the homogeneous threshold power is lowest at the first harmonic of the low-frequency electrostatic-ion Bernstein wave. The relevance of the present investigation to fusion, ionospheric modification experiments, and space plasmas has been pointed out. For example, for fusion plasmas the convective threshold power for channel (i) is found to be approximately 20 kW/${\mathrm{cm}}^2$.