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Backward-propagating source as a component of rising tone whistler-mode chorus generation

Authors :
Vijay Harid
Mark Gołkowski
Poorya Hosseini
Hoyoung Kim
Source :
Frontiers in Astronomy and Space Sciences, Vol 9 (2022)
Publication Year :
2022
Publisher :
Frontiers Media S.A., 2022.

Abstract

Whistler-mode chorus waves in the magnetosphere play a crucial role in space weather via wave–particle interactions. The past two decades have observed tremendous advances in theory and simulations of chorus generation; however, several details of the generation mechanism are still actively contended. To simulate chorus generation, a new envelope particle-in-cell code is introduced. The model produces a rising tone chorus element in a parabolic geomagnetic field. The initial chorus element “embryo” frequency is shown to initialize near the equator at the frequency of maximum linear growth. A backward resonant current is then observed to propagate upstream of the equator. The trajectory of the backward current follows that of a freely falling electron that has been de-trapped at the equator superimposed with forward motion at the group velocity. The backward current iteratively radiates a rising tone element where the highest frequency components are generated furthest upstream. The work provides new advancements in modeling chorus and corroborates other recent work that has also demonstrated a backward-moving source during the generation of coherent whistler-mode waves.

Details

Language :
English
ISSN :
2296987X
Volume :
9
Database :
Directory of Open Access Journals
Journal :
Frontiers in Astronomy and Space Sciences
Publication Type :
Academic Journal
Accession number :
edsdoj.f94ddd1137c47f5a3ed41a280825ff6
Document Type :
article
Full Text :
https://doi.org/10.3389/fspas.2022.981949