A numerical calculation method for frequency-shift of a plasma wave using wave digital filters

It is difficult to measure any quantity in plasmas, since the physical quantity is usually measured only under very severe experimental conditions. For instance, it is often observed that the frequency of the wave changes during propagation and also different waves from the incident one are newly stimulated. Therefore, proposed is the most suitable method for computer experiment using technique of signal processing. In plasmas, various phenomena are described by a fluid theory. The fluid theory consists of a system of Maxwell's equations and that of Euler's equations. Applying the technique of wave digital filters (WDF) to these equation systems, the partial differential equations are integrated directly. Considering all physical quantities as currents, a system of partial differential equation systems is transformed into an equivalent Kirchhoff circuit. Wave-flow diagrams corresponding to their Kirchhoff circuits are obtained by the ordinary WDF procedures, which are algorithms themselves for numerical calculations. Therefore, we may safely say that these algorithms construct a computer experimental apparatus, which simulates many plasma experiments concerning propagation properties of plasma waves. Here, we simulate frequency-shift phenomena of some plasma wave by means of the function with respect to spectrum analysis of this apparatus.