Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

Tue. May 22, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Danny Summers(Memorial University of Newfoundland), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Keisuke Hosokawa(電気通信大学大学院情報理工学研究科, 共同), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University)

[PEM16-P03] Simulation of oblique propagation for whistler mode triggered emissions in a parabolic magnetic field

*Takeshi Nogi1, Yoshiharu Omura1 (1.Reserch Institute for Sustainable Humanosphere, Kyoto University)

We perform two-dimensional electromagnetic particle simulation to study fundamental characteristics of whistler mode wave-particle interaction involved in chorus emissions propagating oblique to the background magnetic field. We assume simple periodic (x, y) system with the parabolic magnetic field taken in the x-direction. With the electrostatic components parallel to the magnetic field, which have been neglected in the previous simulation studies on chorus emissions, the distribution function in position can have a great influence on the simulation results. Assuming energetic electrons with anisotropic subtracted bi-Maxwellian velocity distribution function at the equator, we first put particles under harmonic bounce motion under a parabolic magnetic field. We next follow the motions of the particles adiabatically without any waves to obtain an equilibrium state as the initial distribution for
the particle simulation. It is necessary to put many super-particles in a grid cell to suppress the thermal fluctuation. With 30,000 particles per cell, we have confirmed a good agreement of the wave growth in the parallel direction with the linear growth rate. We next put an array of antennas with obliquely aligned to background magnetic field, and oscillate the antenna current with a variable frequency below the electron cyclotron frequency to excite a large amplitude whistler-mode wave obliquely propagating to the static magnetic field. In addition to the nonlinear trapping of energetic electrons through the cyclotron resonance, another nonlinear trapping of electrons by the Landau resonance takes place. Structures of the nonlinear trapping potentials changes with a varying frequency, affecting the efficiency of energy transfer between the wave and energetic electrons. We study nonlinear evolution of the wave packet, and competing processes of both resonances in accelerating the energetic electrons to higher energies.