Yu.N. Cherkashin, V.A. Eremenko

The diffraction effects arising from the propagation of the wave beam (simple soliton) having the phase perturbation in the initial data. It is shown that the smooth changing of phase function result to the turning effect of soliton at the some angle relatively the initial propagation direction. Those deviations are determined by the skewness of the phase perturbation in the initial data relatively of the soliton center. It is possible to treat that the effective spreading of phase perturbation takes place on the distance along the propagation direction about three - four soliton width and this distance is not depend on the magnitude and form of perturbation. It is possible to consider this distance "time" or distance of the formation for new propagation direction. The soliton trajectory has the three characteristic parts: first one is agree with the initial direction, the phase perturbation on which is not yet become apparent and soliton maximum continue the initial moving; the smooth transition from the initial trajectory state to the new direction; the last part on which the trajectory is the straight line. The three type of phase perturbation are installed: smooth variation, sharp one, the jump. The phase diffusion represents the monotone curve at the smooth perturbation. And the phase diffusion has the additional oscillations.