Oral Presentation

Arase observation of electron pitch angle scattering by Electrostatic Cyclotron Harmonic waves

Author(s): S. Kurita (Nagoya University) et al.

Presenter: Satoshi Kurita (Nagoya University)

Electrostatic Cyclotron Harmonic (ECH) waves have been considered as a candidate to cause pitch angle scattering of electrons in the energy range from a few hundred eV to several tens of keV. Theoretical studies have suggested that electron pitch angle scattering by ECH waves is enhanced at lower pitch angles near the loss cone. Due to the insufficient angular resolution of particle detectors, it was difficult to reveal the ECH- driven scattering based on electron measurements. The present study reports on variation in electron pitch angle distributions associated with intense ECH wave activity observed by the Arase satellite. The variation is characterized by a decrease in electron fluxes at lower pitch angles near the loss cone, and energy and pitch angle dependence of the flux decrease can be reasonably explained by enhanced pitch angle scattering rates predicted by the quasi-linear theory. These observational results give clear evidence for pitch angle scattering driven by ECH waves.