Nonlinear Wave-Particles Interactions in the Outer Radiation Belt: Mechanisms of Interaction and Effects for the Global Particles Dynamics

Friday, 9 March 2018: 09:25
Longshot and Bogey (Hotel Quinta da Marinha)
Oleksiy V Agapitov1, Anton Artemyev2, Ivan Vasko3, Didier Mourenas4, James Frederick Drake1 and Forrest Mozer1, (1)University of California Berkeley, Berkeley, CA, United States, (2)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (3)Space Science Lab, UC berkeley, Moscow, CA, United States, (4)CEA/DAM- ILE DE FRANCE, Savigny-sur-orge, France
PDF
Abstract:
Observations by the Van Allen Probes provide high-quality ELF/VLF measurements of wave electric field component parallel to the ambient magnetic field that revealed new nonlinear electron scales features in the outer radiation belt, important for particle acceleration and scattering and showing the influence of nonlinear wave-particle interactions on the energetic electron distribution over macroscopic spatial scales.

The parallel electric field component of whistler-mode waves provides trapping of hot electrons into the effective potential and in inhomogeneous systems such as the dipole-like geomagnetic field allow an efficient parallel acceleration up to ~20-200 keV eventually leading to bursty precipitation (observed as microbursts at ionospheric altitudes). The mechanisms that produce nonlinear electric field structures, including the nonlinear evolution of oblique whistler-mode waves due to electron trapping and the parametric interaction of whistler waves have been determined. Important nonlinear processes responsible for rapid particle acceleration or scattering, with a significant effect on the global dynamics of the outer radiation belt, are listed below:

- the distribution of high amplitude whistler-mode waves (oblique and parallel) and resonant electron distribution function features in the outer radiation belt are connected self-consistently;

- whistler-mode waves with a large parallel electrostatic component (up to 100 mV/m) may allow Landau trapping of hot electrons into the wave effective potential with rapid parallel acceleration and possible bursty precipitation;

- a prevalence of the hot electron population provides the possibility of generating an electron acoustic mode, and corresponding mechanisms of nonlinear wave-wave coupling lead to the formation of nonlinear parallel electric field bursts from oblique whistlers;

- nonlinear wave-particle interactions with oblique whistlers influence the global dynamics of the electron distribution in the outer radiation belt leading to separate observations of intense very oblique and parallel chorus in the outer radiation belt.

<< Previous Abstract | Next Abstract >>