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Article Dans Une Revue Journal of Geophysical Research Space Physics Année : 2019

Whistler Waves' Propagation in Plasmas With Systems of Small-Scale Density Irregularities: Numerical Simulations and Theory

Résumé

The propagation of whistler waves in a magnetized plasma containingmultiple small-scale (100 m to 1 km) field-aligned irregularities ofenhanced electron density is considered analytically and by means ofnumerical simulations. Such systems of irregularities can develop in theupper ionosphere during the generation of density ducts by high-frequency heating facilities and other types of active experiments. Thesimulation parameters are close to those of an active experiment where awhistler wave of 18 kHz emitted by a ground-based very low frequency(VLF) transmitter was received onboard the DEMETER satellite at 700 kmabove the SURA heater. The study reveals a number of remarkableproperties of the VLF waves' propagation, including the existence ofspecific waveguide modes of the small-scale density structures and of acharacteristic transverse size d0 of the irregularities.Irregularities with small density enhancements around 10-20% andtransverse sizes larger than d0?1 km can serve as separatewaveguides for VLF waves. In their turn, single irregularities narrowerthan d0 cannot be considered as individual ductingstructures. Numerical simulations show that, for the analysis of theelectromagnetic whistlers' propagation, a system of closely spacedirregularities with scales narrower than d0 can be modeled byan equivalent ducting structure with a smoothed density profile. Suchequivalent structure has the same ducting properties for whistlers andcan be produced by averaging with a sliding window of a scale aboutd0 the original density distribution.
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Dates et versions

hal-03742207 , version 1 (02-08-2022)

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I. Yu. Zudin, T. M. Zaboronkova, M. E. Gushchin, N. A. Aidakina, S. V. Korobkov, et al.. Whistler Waves' Propagation in Plasmas With Systems of Small-Scale Density Irregularities: Numerical Simulations and Theory. Journal of Geophysical Research Space Physics, 2019, 124, pp.4739. ⟨10.1029/2019JA026637⟩. ⟨hal-03742207⟩
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