Wave Propagation In Inhomogeneous Plasma Research Articles

Attenuation characteristics of electromagnetic wave in inductive coupled plasma based on variation of discharge power

The application of Inductively Coupled Plasma (ICP) can cause a wide range high density plasma and has great advantages in electromagnetic wave attenuation. Studying the process of interaction between ICP and electromagnetic wave, we established the electromagnetic wave propagation in inhomogeneous plasma, adopted hierarchical model for the diagnosis of the interaction of plasma and electromagnetic wave, and studied the electromagnetic wave attenuation under different conditions of input power. The experiment method of inductively coupled plasma for attenuation electromagnetic wave was proposed. Based on the model of plasma covering over the metal plate, the arch system for measurement of microwave reflectivity of plasma was established. The interaction of closed-plasma and electromagnetic wave with a bandwidth of 4−8 GHz was studied, the effect on microwave reflection of different rf power was evaluated analyzed, and the experimental measurement and calculation results were analyzed. The experimental results show that the inductively coupled plasma attenuates the electromagnetic wave in 5.92−6.8 GHz band obviously by power regulation.

Adaptive finite elements for a set of second-order ODEs

A Hermite finite-elements approach with adaptive mesh refinement for the solution of a set of second-order ordinary differential equations is described. The main advantage of the method is its usability for stiff equations with boundary conditions. For cases where exponentially growing solutions can exist, the method overcomes the common problems of initial value solvers. The method was successfully used for the full-wave solution of wave propagation in inhomogeneous plasma where the mode conversion process between ordinary, extraordinary and electron Bernstein waves occurs.

Congruent reduction in geometric optics and mode conversion

Standard eikonal theory reduces, to N=1, the order of the system of equations underlying wave propagation in inhomogeneous plasmas. The condition for this remarkable reducibility is that only one eigenvalue of the unreduced N×N dispersion matrix D(k,x) vanishes at a time. If, in contrast, two or more eigenvalues of D become simultaneously small, the geometric optics reduction scheme becomes singular. These regions are associated with linear mode conversion and are described by higher-order systems. A new reduction scheme is developed based on congruent transformations of D, and it is shown that, in degenerate regions, a partial reduction of order is still possible. The method comprises a constructive step-by-step procedure, which, in the most frequent (doubly degenerate) case, yields a second-order system, describing the pairwise mode conversion problem in four-dimensional plasmas. This N=2 case is considered in detail, and dimensionality arguments are used in studying the characteristic ordering of the elements of the reduced dispersion tensor in mode conversion regions. The congruent reduction procedure is illustrated by classifying pairwise degeneracies in cold multispecies magnetized plasmas.

On MHD wave propagation in inhomogeneous plasmas and the mechanism of resonant absorption

On MHD wave propagation in inhomogeneous plasmas and the mechanism of resonant absorption

Asymptotic solutions of waves in inhomogeneous plasma with longitudinal magnetic field

The asymptotic solutions to the second-order differential equations governing the wave propagation in inhomogeneous plasma are given where the external magnetic field is assumed to be in the longitudinal direction. The zero-, first-, second-, third-, fourth,- and fifth-order approximations are explicitly given. It is further shown that the third-order asymptotic approximation agrees with the WKBJ approximation. Numerical results for a linear profile of electron concentration are given, and they are found to improve the WKBJ approximation.