Author:

Keywords:

Antennas, Gyrotropy, Green's function, Nuclear Fusion

Abstract:

An extensive growth of the electricity consumption caused by the growth of the population and increased quality of living makes scientists search for alternative ways of energy production. One of such ways is fusion energy. Antennas are one of the key components of the heating systems which make fusion reactions possible. Designing antennas for fusion reactions is a challenging and responsible work. The design tool has to take into account complex features of plasma which is the medium where the heating wave is propagating. While designing such tool difficulties arise due to the complexity which is caused by the tensor nature of the permittivity in case of a gyrotropic medium. The algorithm built within this research is dedicated to the analysis of Ion-Cyclotron Resonance Frequency antennas functioning in the presence of a gyrotropic medium. Several approximations from plasma physics theory will be introduced. Due to the fact that plasma is an ensemble of an enormous amount of charged particles with multiple degrees of freedom simplified mathematical models must be introduced in order to describe such environment. Regardless of the simplicity of such models they should remain applicable to be able to model realistic experimental scenarios. An algorithm for the calculation of the necessary Green’s function is described. Knowing Green’s functions helps in finding the electromagnetic field in any environment. The method used in the Green’s function calculation is significantly different from existing tools. The problematic behaviour caused by the pole and asymptote are removed analytically. The method introduced in this work was validated for the propagation in regular dielectrics (water with losses) or free space. Based on this derivation a tool for the calculation of antennas radiating in a gyrotropic medium can be constructed. Another result of this research is a topology which is a simplified scaled version of a possible ITER type antenna. This antenna was measured for the radiation in lossy dielectric. This experiment has proven that the power launched by the model is coupled to the medium of propagation. The results of this research open opportunities for further investigations in order to include features of antennas for other types of plasma heating. Also an optimization of integration techniques can be performed in order to improve the speed of the calculations. The designs of real antennas which radiate in a gyrotropic medium are the next logical step in research line that was started with this work.