arXiv subjects

Hideki Kawaguchi

Publications and source records attributed to Hideki Kawaguchi.

4 recordsLinked to original sources

arXiv2026

FDTD Simulation of O-X Mode Conversion Process in Non-uniform Magnetized Plasma

Electron Bernstein Waves (EBWs) are electrostatic waves than can propagate in overdense plasmas without density cutoff, making them suitable for high density plasma heating. Since EBWs cannot be directly launched from vacuum, mode conversion processes such as O-X-B conversion are required. In this study, the O-X mode conversion process is investigated using the finite difference time-domain (FDTD) method in a magnetized plasma with non-uniform density. In particular, the dependence of mode conversion characteristics on the incident angle of the injected wave is studied. The results show that an optimal incident angle exists at which the wave propagates without significant attenuation and strong electric field enhancement is observed near the upper hybrid resonance (UHR) layer. When the incident angle deviates from this optimal angle, an evanescent region appears, resulting in attenuation of the wave. These results demonstrate that angular optimization is essential for efficient wave propagation toward the UHR region and EBW excitation.

physics.plasm-ph↗

arXiv2026

Scattering analysis of nano-scale chiral structures in optical vortex using Method of Moments

This paper presents a full 3D Method of Moments (MoM) simulation for analysis of scattering from nano-scale chiral ribbon structures under optical vortex illumination to aim to investigate electromagnetic mechanism of circular dichroism (CD) and optical vortex dichroism (VD). Both twist and helical nano-ribbons are modeled as dispersive materials scatterer. CD and VD are evaluated quantitatively by differences in scattering power. Numerical results demonstrate that angular momentum of optical light induces dichroic response effectively.

cond-mat.mtrl-sci↗

arXiv2025

Consideration on relation between penetrated power and topological charge of millimeter-wave vortex in magnetized plasma

It was demonstrated that the vortex field of a hybrid mode can propagate in the mag-netized plasma region where plane waves are unable to propagate due to the cut-off condition. In this study, the dependence of the penetrated power of injected as millime-ter-wave vortices of the hybrid mode in magnetized plasma is analyzed using the Fi-nite-Difference Time-Domain (FDTD) method. The effect of the radius size of the cor-rugated waveguide on the penetrated power is described, revealing its significant con-tribution to reducing the deviation of topological charge in the hybrid mode. Further-more, it was found that the penetrated power of the vortex field in magnetized plasma strongly depends on the topological charge l and the deviation of topological charge

physics.plasm-ph↗

arXiv2024

The study of propagation characteristics of millimeter-wave vortex in magnetized plasma by using FDTD Method

It is pointed out that millimeter-wave vortex may contribute an efficient plasma heating since it was found that the millimeter-wave vortex can propagate in magnetized plasma even in which the normal plane wave is in cut-off condition. Then, it was assumed that the vortex field was the Laguerre-Gaussian (L-G) mode which is free-space solution, but the generation and stable propagation of the L-G mode vortex are not easy in the millimeter frequency range. On the other hand, it is known that millimeter-wave hybrid mode of cylindrical corrugated waveguide has also vortex property. In this paper, we investigate propagation characteristics of millimeter-wave vortex of a hybrid mode of cylindrical corrugated waveguide in the magnetized plasma by using three dimensional numerical simulations with finite-difference time-domain (FDTD) method.

physics.plasm-ph↗