Kinetics of weakly turbulent wave fields

Only the first nonvanishing term in the expansion of collision integral in powers of wave enrgy is usually considered. Nevertheless the highr collisional terms in the wave kinetic equation can be dominant in the energy range, where the turbulence still remains weak. These terms can be essential even when they are smaller than the first one, if they violate some of the conservation laws correct in the first approximation. The previous attempts to calculate higher nonlinear terms in the wave kinetic equation resulyed in divergencies. Up to now there was no effctive way to aliminate such divergencies. This problem is solved in the present paper with the help of the Wyld's diagram technique. As a result the structure of collision intgral is clear up in everfy order of its power expansion in wave energy and conditions of a kinetic equation applicability are specified. Th cubic collisional term for waves with the decay dispersion law is calculated correctly as an example of application of this method. 15 refs