Nonlinear evolution of lower hybrid waves

Abstract

The two-dimensional steady-state distribution of lower hybrid waves is governed by the complex modified Korteweg–deVries equation, vτ+vξξξ+(‖v‖2v)ξ=0, where v is proportional to the electric field and ξ and τ are two spatial coordinates. The equation is studied numerically. Two types of solitary waves can arise; one is a constant phase pulse, whereas the other is an envelope solitary wave. These solitary waves are not solitons. The occurrence of the constant phase pulses points to the possibility of internal reflections due to scattering off ponderomotive density fluctuations. This necessitates solving the equation as a boundary value problem. With typical fields for lower hybrid heating of a tokamak, it is found that large reflections can occur close to the edge of the plasma.