Two-dimensional depletion of a lower hybrid pump by quasi-mode excitations

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Abstract
In this note we give results of a detailed investigation of the effect of parametric excitation of quasi-modes on the depletion of a lower hybrid pump excited from a finite extent source. Basically, we consider the cou- pling of the electrostatic pump wave potential @,(x) Xexp(- iw,t) with another lower hybrid wave potential @l(x) exp(- iwlt) such that the beat wave with w = wo - wl and k = ko - kl has a phase velocity close to the electron thermal velocity and consequently is heavily damped. The electron density fluctuations corresponding to this low frequency beat mode provide the necessary nonlin- ear coupling between Go and and the nonlinear coupled equations can be written in the form1 (7) where 2a is the effective width of the waveguide aid N is the number of waveguides for a phased array source. Equations (6) and (7) model the excitation of the pump wave from a finite extent source and allow the sideband to exist as noise everywhere (it is assumed to exist as thermal fluctuations with Al < 2,