Full-wave modeling of EMIC wave packets: ducted propagation and reflected waves

Frontiers in Astronomy and Space Sciences

Astronomy and Space Sciences

Wen Li¹  Longzhi Gan¹  Murong Qin¹  Luisa Capannolo¹  Xiao-Chen Shen¹  Qianli Ma²  Miroslav Hanzelka³ 

[1] Center for Space Physics, Boston University, Boston, MA, United States;Center for Space Physics, Boston University, Boston, MA, United States;Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA, United States;Center for Space Physics, Boston University, Boston, MA, United States;Department of Space Physics, Institute of Atmospheric Physics of the Czech Academy of Sciences, Prague, Czechia;

关键词: EMIC waves;    wave propagation properties;    full-wave simulation;    mode conversion;    ducted waves;    reflected waves;    cold plasma;    Earth’s inner magnetosphere Frontiers;   

DOI  :  10.3389/fspas.2023.1251563

 received in 2023-07-01, accepted in 2023-09-26,  发布年份 2023

来源: Frontiers

【 摘 要 】

Electromagnetic ion cyclotron (EMIC) waves can scatter radiation belt electrons with energies of a few hundred keV and higher. To accurately predict this scattering and the resulting precipitation of these relativistic electrons on short time scales, we need detailed knowledge of the wave field’s spatio-temporal evolution, which cannot be obtained from single spacecraft measurements. Our study presents EMIC wave models obtained from two-dimensional (2D) finite-difference time-domain (FDTD) simulations in the Earth’s dipole magnetic field. We study cases of hydrogen band and helium band wave propagation, rising-tone emissions, packets with amplitude modulations, and ducted waves. We analyze the wave propagation properties in the time domain, enabling comparison with in situ observations. We show that cold plasma density gradients can keep the wave vector quasiparallel, guide the wave energy efficiently, and have a profound effect on mode conversion and reflections. The wave normal angle of unducted waves increases rapidly with latitude, resulting in reflection on the ion hybrid frequency, which prohibits propagation to low altitudes. The modeled wave fields can serve as an input for test-particle analysis of scattering and precipitation of relativistic electrons and energetic ions.

【 授权许可】

Unknown   
Copyright © 2023 Hanzelka, Li, Ma, Qin, Shen, Capannolo and Gan.