Numerical Modeling of Electron Precipitation by Coherent Whistler Mode Pulses over a Range of Amplitude and Frequency Sweep Rates
Abstract
The interaction between coherent whistler mode waves and energetic radiation belt electrons can result in pitch angle scattering of electrons into the bounce loss cone. Past modeling efforts have focused on test particle simulations and the computation of diffusion coefficients. However, in the case of large amplitude coherent waves, non-linear effects such as phase-trapping require a full kinetic approach. Since VLF transmitters tend to be narrowband coherent signals, correctly modeling the physics is a crucial step towards controlled precipitation. We compare particle precipitation due to coherent wave-particle interactions using a Monte Carlo Model and a Vlasov-Hybrid Model. The Monte Carlo Model consists of sampling the distribution function with a large number of test particles and tracking the rate at which particles fall into the loss cone. The Vlasov-Hybrid model computes the precipitated distribution using a characteristic based solution of the Vlasov equation. We consider the total precipitation due to 0.5 sec pulses with set frequency sweep rates, characteristic of VLF triggered emissions and magnetospheric chorus elements (-2 to 2 kHz/sec). We consider particle precipitation during quiet and disturbed magnetospheric conditions; the plasma parameters and L-shell used are typical of the Siple wave injection experiment. The results suggest that signals with non-zero frequency sweep rates (risers and fallers) are capable of extending the spatial extent of the resonant interaction and can precipitate more particles than monochromatic signals.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSM24B..04H
- Keywords:
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- 2716 MAGNETOSPHERIC PHYSICS Energetic particles: precipitating;
- 2753 MAGNETOSPHERIC PHYSICS Numerical modeling;
- 2774 MAGNETOSPHERIC PHYSICS Radiation belts