Beam Tracing in Phase Space: Paraxial Description of High-Frequency Wave Beams in Turbulent Plasmas

The averaged wave energy density carried by an electron-cyclotron wave beam in a turbulent plasma can be computed by solving numerically the wave kinetic equation. This approach however can be computationally demanding due to the high dimensionality of the problem. In this work, we show how ideas from paraxial optics can be applied to construct an approximate solution of the wave kinetic equation. This construction requires only the solution of a small system of ordinary differential equations.