Cooperation of deterministic and stochastic mechanisms resulting in the intermittent behavior

Intermittent behavior near the boundary of chaotic phase synchronization in the presence of noise (when deterministic and stochastic mechanisms resulting in intermittency take place simultaneously) is studied. The noise of small intensity is shown to do not affect on the characteristics of intermittency whereas the noise of large amplitude induces new effects near the boundary of the synchronous regime. In the first case the eyelet intermittency takes place near the boundary of the synchronous regime, in the second one the ring intermittency or coexistence of both types of intermittency is realized. Main results are illustrated using the example of two unidirectionally coupled Rössler systems. Similar effects are shown to be observed in coupled spatially distributed Pierce beam-plasma systems.