On modulational interaction of lower-hybrid waves

The general nonlinear equation of the third order in field strength for the lower-hybrid (LH-)waves is obtained on the basis of kinetic theory. This equation enables us to describe strong turbulence effects [modulational instability (MI), soliton-like solutions, etc.] as well as weak turbulence effects (decays, scattering). The MI of the LH-waves propagating at the angles Θ0 with respect to the external magnetic field such as 1 >> cos Θ0 ≥ (m/M)1/2, where m/M is the electron to ion mass ratio, is investigated. The situation when the MI prevails over the induced scattering and decay effects is shown to be possible even for the case of sufficiently low density of the pump wave energy. The condition on the wave-vectors is obtained for the pump wave of sufficiently low intensity; it is shown that if this condition takes place then the character of the ''short-scale'' MI (vertical stroke Δkvertical stroke >> vertical strokek0vertical stroke where Δk, k0 are the wavevectors of the density modulation and the pump wave respectively) differs from the character of the parametric instability (vertical strokek0vertical stroke = 0) essentially. The influence of the LH-wave MI on the current drive generation is considered