Influence of a periodic external force on three-wave decay

The alteration of the dynamics of a wave triplet by regular, external, periodic forces are analyzed. The triplet is treated as decaying due to harmonic forces. Increasing damping forces lead to the alternating appearances of chaotic and regular, ordered regions. Further, the external forces are found capable of randomizing or regularizing the chaotic motion of a self-excited system. The break-up of a strange attractor in the ordered Lorentz system can only be accomplished by an external force with an amplitude exceeding the maximum amplitudes of intersecting modes.