Yu. A. Ryzhov

Turbulent spreading of artificial periodic inhomogeneities in the lower ionosphere

We discuss the turbulent relaxation of artificial periodic electron density inhomogeneities (lattices) under conditions characteristic of the D region of the ionosphere. For uniform, isotropic turbulence, the relaxation time is determined by the mean square velocity of turbulent motion and the scale of the inhomogeneity.

Bragg resonator in ionospheric plasma with artificial quasiperiodic lattice

Scattering of electromagnetic waves on an artificial ionospheric quasiperiodic lattice produced by the field of a high power pump wave is considered. It is shown that in the presence of a reflection point (mirror) and with a certain frequency spacing between incident and pump waves, formation of a semiopen type Bragg resonator in the lattice-mirror system is possible. In this case the field within a relatively large region about the mirror increases sharply. This increase is limited by the presence of coarse scale chaotic inhomogeneities in the electron density. Numerical estimates are presented for the terrestrial ionosphere.

Exciting a Bragg resonator in an ionospheric plasma containing an array

Excitation by an incident pulsed signal is considered for an ionospheric Bragg resonator formed by an artificial periodic array in the presence of a mirror (point of reflection). The trial wave is an infinite square pulse and the carrier frequency. An approximate study is made of the shape of the reflected signal and it is shown that the pulse buildup time at the exit from the layer (resonator excitation time) is substantially dependent on the pumping frequency, array modulation depth, and resonator quality factor.

Statistical description of dynamical systems under the action of random forces

ConclusionsWe have arrived at a statistical description of the solutions of the stochastic system (1) by means of two transition probability distribution functions and , each of which has associated with it a pair of kinetic equations. If no special assumptions are made with regard to the nature of the random forces or their higher moments, then only for sufficiently small fluctuations of the right-hand sides of the system (1) do these equations have a comparatively simple form. We point out that the resulting equations can be derived by the method developed in [10–12]. Analogous problems for linear differential equations are discussed in a recent paper [20].