On the spectra of natural waves in a plasma waveguide in the presence of collisions

The dispersion characteristics of surface and evanescent waves in metal-dielectric-plasma-dielectric-metal structure in the presence of collisions are investigated analytically and numer ically. In the absence of absorption, when the electron density passes through the doubled critical value, a rearrangement of the eigenwave structure, associated with the appearance of surface waves, occurs. A rearrangement also occurs in an absorbing plasma, but the numbers of reconnecting modes depend on the size of the structure and the ratio of the electron collision frequency to the field frequency. Correct consideration of this process is necessary for the analytical analysis of the field structure in plasma reactors, the design of plasma antennas, and the solution of other problems of plasma electrodynamics.

AN APPLICATION OF MICROWAVES REFRACTION FOR INHOMOGENEOUS PLASMA DIAGNOSTIC

A brief review of the main microwave diagnostics methods of inhomogeneous plasma based on the refraction of microwaves is given. These methods make it possible to determine the plasma density distribution, the magnetic field distribution, the electron collision frequency, and the electron temperature profile. In addition, the determination of the average density of the peripheral plasma layers and the local inhomogeneities of the rotating plasma are also possible. The effect of refraction on the accuracy of determining the plasma parameters by using microwave methods for plasma diagnostics is considered.

Thomson scattering from Langmuir fluctuations in a parabolic layer of a collisional plasma

Thomson scattering of a probe wave by the Langmuir fluctuations inside a plasma layer with a parabolic density profile is considered. The collisional damping of plasma fluctuations is taken into account. The plasma line part of the scattered spectrum is calculated depending on the layer thickness, electron collision frequency, and the form of the distribution functions for the electrons and ions. Simple analytic expressions for the plasma line shape and characteristic spectrum width are found. It is shown that this plasma line is asymmetric, and the asymmetry depends on the layer type (maximum or minimum). Some important plasma parameters, such as the electron collision frequency and the sign of the electron density deviation inside the layer can be obtained from the plasma line spectrum calculated in this paper.