Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation

Abstract The interaction of very low frequency transmitter signals with radiation belt electrons depends ultimately on their wave normal angles. In the equatorial interaction region, these can be either low (ducted propagation) or comparatively large (nonducted propagation). Experimentally distingui...

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Main Authors: F. Němec, O. Santolík, G. B. Hospodarsky, W. S. Kurth
Format: Article
Language:English
Published: Wiley 2022-06-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1029/2022GL098328
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author F. Němec
O. Santolík
G. B. Hospodarsky
W. S. Kurth
author_facet F. Němec
O. Santolík
G. B. Hospodarsky
W. S. Kurth
author_sort F. Němec
collection DOAJ
description Abstract The interaction of very low frequency transmitter signals with radiation belt electrons depends ultimately on their wave normal angles. In the equatorial interaction region, these can be either low (ducted propagation) or comparatively large (nonducted propagation). Experimentally distinguishing the two modes is complicated, as multicomponent spacecraft data typically do not extend to high enough frequencies with a sufficient frequency resolution. One exception that we exploit are 11.9 kHz signals from Alpha transmitters detectable by the Van Allen Probes spacecraft. We use multicomponent burst mode measurements to distinguish between the ducted and nonducted modes of propagation and to evaluate their relative importance. While the ducted waves are detected less often, they tend to have larger Poynting fluxes. The total power propagating in the two modes is thus comparable. Magnetic local time and in‐situ density fluctuations are main parameters controlling the relative fraction of ducted waves.
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spelling doaj-art-bc27133ca88241f3aa4299f59145b9e82025-01-22T14:38:16ZengWileyGeophysical Research Letters0094-82761944-80072022-06-014912n/an/a10.1029/2022GL098328Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted PropagationF. Němec0O. Santolík1G. B. Hospodarsky2W. S. Kurth3Faculty of Mathematics and Physics Charles University Prague Czech RepublicFaculty of Mathematics and Physics Charles University Prague Czech RepublicDepartment of Physics and Astronomy University of Iowa Iowa City IA USADepartment of Physics and Astronomy University of Iowa Iowa City IA USAAbstract The interaction of very low frequency transmitter signals with radiation belt electrons depends ultimately on their wave normal angles. In the equatorial interaction region, these can be either low (ducted propagation) or comparatively large (nonducted propagation). Experimentally distinguishing the two modes is complicated, as multicomponent spacecraft data typically do not extend to high enough frequencies with a sufficient frequency resolution. One exception that we exploit are 11.9 kHz signals from Alpha transmitters detectable by the Van Allen Probes spacecraft. We use multicomponent burst mode measurements to distinguish between the ducted and nonducted modes of propagation and to evaluate their relative importance. While the ducted waves are detected less often, they tend to have larger Poynting fluxes. The total power propagating in the two modes is thus comparable. Magnetic local time and in‐situ density fluctuations are main parameters controlling the relative fraction of ducted waves.https://doi.org/10.1029/2022GL098328Alpha transmittersductednonductedwave analysis
spellingShingle F. Němec
O. Santolík
G. B. Hospodarsky
W. S. Kurth
Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
Geophysical Research Letters
Alpha transmitters
ducted
nonducted
wave analysis
title Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
title_full Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
title_fullStr Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
title_full_unstemmed Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
title_short Alpha Transmitter Signals Observed by the Van Allen Probes: Ducted Versus Nonducted Propagation
title_sort alpha transmitter signals observed by the van allen probes ducted versus nonducted propagation
topic Alpha transmitters
ducted
nonducted
wave analysis
url https://doi.org/10.1029/2022GL098328
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AT osantolik alphatransmittersignalsobservedbythevanallenprobesductedversusnonductedpropagation
AT gbhospodarsky alphatransmittersignalsobservedbythevanallenprobesductedversusnonductedpropagation
AT wskurth alphatransmittersignalsobservedbythevanallenprobesductedversusnonductedpropagation