Magnetosphere Seminars

Using Electron Flux Oscillations as Indicators of ULF Wave Radial Diffusion

Speaker:Theodore Sarris [Democritus University of Thrace‚Äč]
Date:Tuesday, Jul 17, 2018
Time:3:30 pm
Location:LASP Space Science Building, room N100 (1st floor)

Seminar Abstract:

We investigate the parameters affecting the appearance and amplitudes of 100s-keV electron flux oscillations, which appear under the effect of Ultra Low Frequency (ULF) fluctuations in the magnetosphere. To this direction, particle tracing simulations are conducted through a parametric study. It is found that the width in energy of electron energy channels are a critical parameter, with narrower energy channels enabling the observation of higher amplitude flux oscillations; this could explain why such features were not routinely observed before the Van Allen Probes era, except for large-amplitude drift echoes following a storm or substorm, as past spacecraft missions generally had lower energy resolution. Flux oscillations are also governed by the local gradient of the Phase Space Density, with steeper gradients leading to higher flux oscillation amplitudes. A third parameter is the power of ULF wave electric and magnetic fluctuations, with higher field amplitudes leading to higher flux oscillations. Finally, the effects of azimuthal wave number, field power spectrum and ULF wave azimuthal localization are discussed. Such effects are quantified and parametrized.