[P-EM17] Space Plasma Physics: Theory and Simulation

[PEM17-P04] Numerical Simulations on Antenna Impedance Resonant Properties in a Lower Hybrid Frequency Range

Koshiro Kusachi¹, *Yohei Miyake¹, Hideyuki Usui¹, Ibuki Fukasawa², Satoshi Kurita², Hirotsugu Kojima² (1.Graduate School of System Informatics, Kobe University, 2.Research Institute for Sustainable Humanosphere, Kyoto University)

Keywords:Space plasma, Antenna impedance, Lower hybrid frequency, Plasma waves, Numerical simulation

For the plasma wave observations in space, the electric field sensor based on a dipole antenna is commonly put in use onboard scientific satellites. The antenna characteristics in space are different from those on the ground due to the dispersive nature of space plasma. Since the observed wave data are calibrated taking into account the antenna characteristics, it is important to understand them quantitatively for correct interpretation of the observational data. Recently, we initiated the numerical study of antenna characteristics in a low-frequency range where the ion dynamics are involved. In this study, we numerically investigate the complex impedance of a dipole antenna placed in a weakly magnetized plasma. In the simulation result, we observed an impedance resonance near the lower hybrid resonance frequency . To clarify the relationship between the impedance resonance and relevant plasma wave modes, we derived dispersion relations from the simulations. A special attention is paid to a wavenumber k_half, where the antenna behaves as a half-wave dipole. We found that the impedance resonance frequency roughly coincides with the frequency at which a lower hybrid wave blanch intersects a wavenumber range near k_half. We also report recent progress on the impedance resonance dependence on plasma conditions.