Direct Evidence of the Pitch Angle Scattering of Relativistic Electrons Induced by EMIC Waves. Issue 4 (11th February 2020)

• Record Type: Journal Article
• Authors: Zhu, Hui; Chen, Lunjin; Claudepierre, Seth G.; Zheng, Liheng
• Is Part Of: Geophysical research letters. Volume 47:Issue 4(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-11
• Subjects: EMIC waves -- pitch angle scattering -- nonlinear wave‐particle interaction -- Van Allen Probes; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL085637
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: In this study, we analyze an electromagnetic ion cyclotron (EMIC) wave event of rising tone elements recorded by the Van Allen Probes. The pitch angle distributions of relativistic electrons exhibit a direct response to the two elements of EMIC waves: at the intermediate pitch angle, the fluxes are lower; and at the low pitch angle, the fluxes are higher than those when no EMIC was observed. In particular, the observed changes in the pitch angle distributions are most likely to be caused by nonlinear wave‐particle interaction. The calculation of the minimum resonant energy and a test‐particle simulation based on the observed EMIC waves support the role of the nonlinear wave‐particle interaction in the pitch angle scattering. This study provides direct evidence for the nonlinear pitch angle scattering of electrons by EMIC waves. Key Points: Direct evidence of EMIC‐induced pitch angle scattering of relativistic electrons is observed The nondiffusive pitch angle distributions of electrons indicate the importance of nonlinear wave‐particle interaction The calculation of minimum resonance energy and a test‐particle simulation support the observations