Langmuir wave linear evolution in inhomogeneous nonstationary anisotropic plasma

Abstract

A hydrodynamic equation describing the linear evolution of a nondissipative Langmuir wave in inhomogeneous nonstationary anisotropic plasma without magnetic field is derived in the geometrical optics approximation. The continuity equation for the wave action density, anticipated from general principles, is then confirmed ab initio, and the conditions for the action conservation are formulated. Given those, the wave field Ẽ universally scales with the electron density N as Ẽ ∝ N3/4 in homogeneous plasma, whereas the wavevector evolution varies depending on the wave geometry. © 2009 American Institute of Physics.