МЕТОДИКА КОНТРОЛЯ ПАРАМЕТРОВ ПЛАЗМЫ ДЛЯ АНТЕННЫХ ИЗМЕРЕНИЙ
Authors: Аль-Абади М. С. 
Published: February 2025

Исследована методика контроля параметров плазмы для антенных измерений с использованием макета из люминесцентных ламп низкого давления. Физические параметры плазмы в макете были получены с помощью измерений микроволновой интерферометрии. С помощью аналитической модели показано, что данный слой поглощает почти половину полосы частот падающего излучения. Заметная диссипация электромагнитных волн в полосе частот позволяет рассматривать тонкий слой плазмы как плазменный поглотитель.

Introduction. There are three different situations of interaction of waves with a plasma medium under different circumstances. These circumstances include the relationship between the plasma electron frequency, the frequency of collisions of plasma electrons with neutrons, and the angular frequency of the incident wave in a homogeneous plasma. In the research of Alireza Gayhlo et al., there is proposed a very interesting method for monitoring plasma parameters by probing a flat thin layer of plasma with a plane wave. The simulation was carried out with the use of the CST application. The discrepancy was large (on average 30%), except for a single point with a frequency of 43 Grad / s, where it reached 10%. Such a large discrepancy does not allow one to use this technique for application in antenna technology and rises the urgency of further research into this approach. The aim of the research is to improve the accuracy of the method in question. In order to achieve it, it is supposed to address the following objectives: 1- apply a state-of-the-art model of sensing a layered medium, which takes into account not only the plasma itself, but also the effect of glass walls of luminescent lamps, and consider a three-layer model, that is equivalent in volume of plasma and glass to a real model of lamps. 2 – replace the matrix model with an exact analytical one, free from errors that arise when multiplying matrices with a large number of layers. 3 – carry out additional experiments in the switched off plasma mode to assess the influence of the structural elements of the model on the measurement results. Methodology. The study is based on the fact that a plane inhomogeneous field can be modeled by a piecewise homogeneous medium with the use of formulas that give an exact solution for partially homogeneous layered media and allow one to calculate the field in any layer from the known field of the incident wave. The results of measurements of the coefficients of reflection and transmission of waves for a plasma frequency of Rad are the closest to the simulation outcomes where the real part of the plasma dielectric constant was 0.95, and the imaginary part was -0.5. In the experiment [14] with the plasma switched on, the discrepancy in the entire range was 30% and only at a single point reached a minimum value of 10%. In our experiment, over the entire range, the discrepancy between the results of measurements and calculations of the reflection coefficients did not exceed 4%. The same results were observed with the plasma switched off. Conclusion. The consistency of the numerical and experimental results of measuring the reflection coefficients increased by at least six times compared with those known from the literature [14], and the achieved accuracy allows one to use this technique to control plasma parameters for various problems. In particular, for antenna engineering. Appropriate consistency between the experimental and numerical results in two modes of sensing for switched on and off plasma indirectly with a high probability verifies the adequacy of the applied analytical model and the possibility of using the Drude model for the considered range of frequencies and plasma parameters.