  It is shown, that at weakly nonlinear interaction of waves are possible as
modes with chaotic dynamics, and with increasing degree of coherence.
Conditions are found at which they arise. One of the types of such interaction
is decays. The important features of such processes in plasma are modes with
cascades. They arise in that case when the high-frequency wave which has
appeared as a result of decay can take part in new decay. Chaotic dynamics of
decays can be used for formation of spectra of excited oscillations. For
realization of such possibility the dispersive properties of a cylindrical wave
guide partially filled by magnetoactive plasma are investigated. It is shown,
that such electrodynamic structure is convenient for realization as regular and
chaotic modes.
