Ion hole formation and nonlinear generation of Electromagnetic Ion Cyclotron waves: THEMIS observations

Shoji, Masafumi

Ion hole formation and nonlinear generation of Electromagnetic Ion Cyclotron waves: THEMIS observations

Thursday, 8 March 2018

Lakehouse (Hotel Quinta da Marinha)

Masafumi Shoji, Nagoya University, Institute for Space-Earth Environmental Laboratory (ISEE), Nagoya, Japan, Yoshizumi Miyoshi, Nagoya University, Nagoya, Japan, Yuto Katoh, Tohoku University, Sendai, Japan, Kunihiro Keika, The University of Tokyo, Department of Earth and Planetary Science, Tokyo, Japan, Vassilis Angelopoulos, UCLA, Department of Earth, Planetary, and Space Sciences and Institute of Geophysics and Planetary Physics, Los Angeles, CA, United States, Satoshi Kasahara, The university of Tokyo, Tokyo, Japan, Kazushi Asamura, ISAS/JAXA, Sagamihara, Japan, Satoko Nakamura, Kyoto University, Graduate School of Science, Kyoto, Japan and Yoshiharu Omura, Kyoto University, Research Institute for Sustainable Humanosphere, Kyoto, Japan

Abstract:

Electromagnetic plasma waves are thought to be responsible for energy exchange between charged particles in space plasmas. Such an energy exchange process is evidenced by phase space holes identified in the ion distribution function and measurements of the dot product of the plasma wave electric field and the ion velocity. We develop a method to identify ion hole formation, taking into consideration the phase differences between the gyro-motion of ions and the electromagnetic ion cyclotron (EMIC) waves. Using this method, we identify ion-holes in the distribution function and the resulting nonlinear EMIC wave evolution from THEMIS observations. These ion holes are key to wave growth and frequency drift by the ion currents through nonlinear wave particle interactions, which are identified by a computer simulation in this study.