Langmuir wave linear evolution in inhomogeneous nonstationary anisotropic plasma

Abstract

Equations describing the linear evolution of a non-dissipative Langmuir wave in inhomogeneous nonstationary anisotropic plasma without magnetic field are derived in the geometrical optics approximation. A continuity equation is obtained for the wave action density, and the conditions for the action conservation are formulated. In homogeneous plasma, the wave fieldẼ universally scales with the electron density N asẼ ∝ N 3/4 , whereas the wavevector evolution varies depending on the wave geometry.

Axiomatic geometrical optics, Abraham-Minkowski controversy, and photon properties derived classically

“…We also suggest Refs. [66,144,160,163] as recent illustrations of how advantageous it is for analyzing the linear wave dynamics in plasmas. In addition, the nonlinear Lagrangian theory has been getting a new spin recently, namely, in the context of plasma waves carrying autoresonantly trapped particles [106][107][108][109]161].…”

Current drive in recombining plasma

“…Recently, however, a number of studies [11][12][13][14][15] of waveparticle interactions in nonstationary plasmas has revealed previously unexplored phenomenology and potentially useful mechanisms. Such phenomena are intrinsically non-steady-state, and hence require a modification of the methods typically used to analyze and describe the physics in stationary systems.…”

“…Such phenomena are intrinsically non-steady-state, and hence require a modification of the methods typically used to analyze and describe the physics in stationary systems. In particular, References [11][12][13][14][15] focus primarily on non-steady-state effects associated with expanding or compressing plasma. When a wave is embedded in such a nonstationary plasma and is undamped initially, modification of the bulk plasma parameters through the nonstationary processes changes the wave dynamics and can lead to an induced waveparticle resonance with the fast-particles on the tail of the bulk plasma distribution [12].…”

Nonlinear Amplification and Decay of Phase-Mixed Waves in Compressing Plasma

“…Adiabatic effects.-Except for a minor frequency shift [13], the initial phase-mixed wave is approximately linear, so its early evolution conserves the linear action, I = V (W/ω) dV, where V is the plasma volume [19]. Thus I = N I 0 , where N .…”

“…1(a)] in plasma, which then is compressed perpendicularly to the wave vector, k. While k is fixed at transverse compression [19], the frequency, ω, increases, approximately following the increasing plasma frequency, ω p . Electrons that were trapped initially are then accelerated such that their average velocity remains equal to the phase velocity, u = ω/k [ Fig.…”