Bibliography



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Found 2 entries in the Bibliography.


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2015

Approximate analytical formulation of radial diffusion and whistler-induced losses from a pre-existing flux peak in the plasmasphere

Modeling the spatio-temporal evolution of relativistic electron fluxes trapped in the Earth\textquoterights radiation belts in the presence of radial diffusion coupled with wave-induced losses should address one important question: how deep can relativistic electrons penetrate into the inner magnetosphere? However, a full modelling requires extensive numerical simulations solving the comprehensive quasi-linear equations describing pitch-angle and radial diffusion of the electron distribution, making it rather difficult to perform parametric studies of the flux behavior. Here, we consider the particular situation where a localized flux peak (or storage ring) has been produced at low L < 4 during a period of strong disturbances, through a combination of chorus-induced energy diffusion (or direct injection) at low L together with enhanced wave-induced losses and outward radial transport at higher L. Assuming that radial diffusion can be further described as the spatial broadening within the plasmasphere of this pre-existing flux peak, simple approximate analytical solutions for the distribution of trapped relativistic electrons are derived. Such a simplified formalism provides a convenient means for easily determining whether radial diffusion actually prevails over atmospheric losses at any particular time for given electron energy E and location L. It is further used to infer favorable conditions for relativistic electron access to the inner belt, providing an explanation for the relative scarcity of such a feat under most circumstances. Comparisons with electron flux measurements on board the Van Allen Probes show a reasonable agreement between a few weeks and four months after the formation of a flux peak.

Mourenas, D.; Artemyev, A.; Agapitov, O.V.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2015

YEAR: 2015     DOI: 10.1002/2015JA021623

inner belt; Keywords: radial diffusion; Radiation belts; Van Allen Probes

2013

Scattering rates of inner belt protons by EMIC waves: A comparison between test particle and diffusion simulations

Inner belt energetic protons are a hindrance to development of space technologies. The emission of electromagnetic ion cyclotron (EMIC) waves from spaceborne transmitters has been proposed as a way to solve this problem. The interaction between particles and narrowband emissions has been typically studied using nonlinear test particle simulations. We show that this formulation results in a random walk of the inner belt protons in velocity space. In this paper we compute bounce-averaged pitch angle diffusion rates from test particle simulations and compare them to those of quasi-linear theory for quasi-monochromatic EMIC waves interacting with inner belt protons. We find that the quasi-linear solution is not sensitive to the frequency bandwidth for narrow distributions. Bounce-averaged diffusion coefficients from both approaches are in good agreement for all energies and pitch angles. The interaction with inner belt protons, therefore, can be addressed using quasi-linear diffusion codes, which allows faster exploration of parameter space.

de Soria-Santacruz, M.; Orlova, K.; Martinez-Sanchez, M.; Shprits, Y;

Published by: Geophysical Research Letters      Published on: 09/2013

YEAR: 2013     DOI: 10.1002/grl.50925

EMIC; inner belt; wave-particle interactions



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