SYNCHRONIZATION VS. STOCHASTIZATION OF PHASES IN 4-WAVE INTERACTION

A one dimensional system describing the interaction of three Langmuir waves and an ion-sound wave at the exact resonance is considered. This model includes the energy source and the dissipative regions, and can describe both decay instability and four-wave processes such as modif ied decay. These two kinds of instabilities appear to have quite diffe rent dynamics. The decay instability exhibits a phenomenon known as '' chaotic synchronization'' between the phases, which is associated with a transition from three-wave processes to four-wave process. Converse ly, the ''modified decay'' instability shows an abrupt transition from the regular behavior to the phase stochastization.