Spoke-like irregularities and nonlinear plasma waves in Saturn rings

The process of spoke-like irregularity formation in Saturn rings is discussed. The consideration is carried out within the frame of the model of a plane plasma layer, where quasielectrostatic waves being propagated, which cause periodic changes of matter density and charge in rings. Spokes set in groups, which rotate almost at the same rate with the planet. The conclusion is made that the less is the number of spokes in the group, the more contrasting they should be standing out on the ring background