Induced Scattering and Two-Photon Absorption of Alfven Waves with Arbitrary Propagation Angles

The equation for temporary evolution of spectral energy of collisionless Alfven waves is derived in framework of weak turbulence theory. The main nonlinear processes for such conditions are induced scattering and two quantum absorption of Alfven waves by thermal ions. The equation for velocity distribution of thermal particles is derived that describes diffusion in momentum space due to this nonlinear processes. Comparison is done with the results of another authors. Results obtained are qualitatively differ from the ones obtained for the case of Alfven waves propagation along mean magnetic field.