[P-EM10] Dynamics of Magnetosphere and Ionosphere

[PEM10-P17] The source altitude distribution and heating property of electron conic
estimated with the Arase satellite

*Hiroki Ishimaru¹, Shun Imajo¹, Yoshizumi Miyoshi², Yoichi Kazama⁴, Kazushi Asamura³, Ayako Matsuoka¹, Shiang-Yu Wang⁴, Sunny W. Y. Tam⁵, Chae-Woo Jun², Tomoaki Hori², Iku Shinohara³, Fuminori Tsuchiya⁶, Atsushi Kumamoto⁶, Yoshiya Kasahara⁷ (1.Graduate School of Science, Kyoto University, 2.Institute for Space-Earth Environmental Research, Nagoya University, 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 4.Academia Sinica, 5.National Cheng Kung University, 6.Planetary Plasma and Atmospheric Research Center, Graduate School of Science, Tohoku University, 7.Emerging Media Initiative, Kanazawa University)

Keywords:Electron conics, Auroral acceleration region

We examined the source altitude of electron conics by analyzing high-angular resolution electron data obtained by the Arase satellite. We surveyed electron conic events between 2017 and 2021 and identified electron conics with ion beams observed at an altitude of ~30,000 km above the auroral acceleration region. Assuming that the observed electron conics have adiabatically moved upward from the source altitude and undergone a potential difference along the dipole field line, we fit energy-dependent loss cone curves to the electron flux distribution of the conics to estimate the mirror ratio and the potential difference between the source and the satellite altitude. The electron conic source altitude approximately matched the simultaneously observed AKR source altitude, at which a parallel electric field is formed. In particular, the coincidence of the middle of the source altitude with the bottom altitude of the AKR suggests that heating is related to the time spent in the acceleration region. This result suggests two hypotheses for the generation of electron conics: electron heating due to time-varying electric fields that accelerate auroral electrons, and diffusive heating due to waves, such as electrostatic waves seen around this altitude. We also compared the phase space densities of downward and upward electrons to determine their heating property. We find that the number flux of upward and downward electrons are constant, while the energy fluxes vary widely, which implies that the magnetospheric electrons are heated.