Combined Scattering of Suprathermal Electrons by Whistler‐Mode Chorus and Electromagnetic Ion Cyclotron Waves in the Low‐Density Plasmatrough
Jiang Yu, Jing Wang, Zhaoguo He, Nigang Liu, Kun Li, Aojun Ren, L. Y. Li, Jun Cui, Jinbin Cao
Abstract
Abstract Based on the observation from Van Allen Probes, we report an event of intense and simultaneous electromagnetic ion cyclotron (EMIC) and chorus waves inside the low‐density plasmatrough. By calculating the scattering rates and performing the diffusion simulations, we for the first time evaluate the combined scattering of suprathermal electrons by EMIC and chorus waves in the low‐density plasmatrough. Landau acceleration of suprathermal electrons by EMIC waves is mainly restricted at large pitch angles while their scattering loss by chorus waves occurs at small pitch angles well below 90°. When EMIC and chorus waves are simultaneously present, the scattering of suprathermal electrons by the two waves is very different from that by each type of waves alone. EMIC waves play a complementary role in the scattering of suprathermal electrons by chorus waves, which facilitate the scattering of suprathermal electrons over all pitch angles. The near‐equatorially minoring suprathermal electrons are firstly scattered toward intermediate pitch angles by EMIC waves and further toward the loss cone by chorus waves. Our results highlight the complementary role of different types of magnetospheric waves in the suprathermal electron scattering, which potentially have vital implications for the dynamics of suprathermal electrons in the planetary magnetosphere.