Abstract
This paper studies extremely-low frequency (ELF) whistler-mode waves’ behavior within small-scale magnetic field irregularities in the Earth’s magnetosphere, known as magnetic ducts. Based on the magnetic fields’ magnitude inside and outside these ducts, they are categorized as high-magnetic ducts (HBD) and low-magnetic ducts (LBD). Using the whistler-mode dispersion relation analysis, our primary focus is to show that LBDs are prone to leak electromagnetic energy outside the duct. We further investigate the hypothesis that whistlers can propagate within LBDs without any signal loss when the width of the duct corresponds to an integer multiple of the perpendicular wavelengths of the waves inside it. This condition offers a straightforward and effective method for identifying non-leaking eigenmodes of LBDs. Our analysis of this non-leaking condition reveals that every LBD possesses a finite number of non-leaking eigenmodes directly proportional to the duct’s width and the magnitude of the ambient magnetic field within it. The analytical results are then validated using two-dimensional, time-dependent simulations of the electron-Magnetohydrodynamics (EMHD) model. Also, we model the non-leaking propagation of an ELF whistler-mode wave observed inside the LBD by the NASA Magnetospheric Multiscale mission (MMS) satellites
Original language | American English |
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Journal | JGR-Space Physics |
DOIs | |
State | Published - Sep 26 2023 |
Externally published | Yes |
Keywords
- whistler-mode waves
- VLF waves
- magnetic duct
- magnetosphere
- density duct
- MMS satellites
Disciplines
- Atmospheric Sciences