Speaker
Description
The relativistic dielectric tensor is necessary to model wave propagation and absorption in high-temperature magnetized plasmas. In fusion plasmas, electron cyclotron resonance heating (ECH) requires ray-tracing calculations to evaluate a heating location and a heating efficiency in plasmas. In this study, for a non-uniform medium, a full-wave approach is applied to simulating the propagation and absorption of EC waves in combination with the weakly relativistic dielectric tensor [1]. A finite element method is adopted for the full-wave approach.
The background medium is set to the electron density of 2×10$^{19}$ m$^{-3}$ and electron temperature of 5.76 keV in a two-dimensional rectangular area of 65 mm × 50 mm. An EC wave with a Gaussian profile starts from the left boundary of the area and propagates as an O-mode in the increasing magnetic field B$_z$. We confirmed that an EC wave decays across the EC resonance layer in Figure 1. To characterize the wave absorption on the electron temperature, the absorption efficiency (|S$_0$|-|S$_{out}$|)/|S$_0$| is evaluated from the line integral of the Poynting vector |S| of electromagnetic waves, where the subscripts 0 and out indicate the locations at the input and the opposite boundaries, respectively. The absorption efficiency increases up to 100%, as the electron temperature increases from 0 to more than 20 keV. In another situation, when a density cutoff exists in the area, EC waves reflect at the cutoff layer. This demonstration attains insight into the behaviour of electromagnetic waves in weakly relativistic plasmas.
