Spatial autoresonance: Enhancement of mode conversion due to nonlinear phase locking

L. Friedland
1992 Physics of Fluids B Plasma Physics  
It is shown that the inclusion of weak nonlinearities may have a profound effect on the conservative linear mode conversion in inhomogeneous media. The phenomenon is demonstrated by adding a quadratic nonlinearity to the conventional system of integral equations describing spatial evolution of linear multicomponent waves. The nonlinear generalization of the reduced coupled mode equations then shows the possibility of a persistent interaction between the modes via the "spatial autoresonance,"
more » ... autoresonance," i.e., the spatial selfadjustment of the nonlinear resonance condition. For a sufficiently strong nonlinearity this adjustment either (a) discontinues at some point when both interacting modes have the same action density sign and the initially excited mode transfers its action flux to the second mode, or (b) prevails indefinitely, in the case of positive-negative action density mode couplings, as the magnitudes of both modes grow continuously in space. The conditions for the spatial autoresonance are found and the effect is illustrated by numerical examples. 3199
doi:10.1063/1.860426 fatcat:i3vi2rqzu5d53j3laopxjca2ke