SPRG Seminars
February 4, 2014:
"Contribution of a scale-changing technique to the characterization of radial diffusion"
Solène Lejosne, British Antarctic Survey, Natural Environment Research Council, Cambridge, England UK
In the sixties, experimental evidence was found indicating that magnetically trapped particles of external origin were transported in the outer zone of the Earth's radiation belts by processes consistent with the conservation of the first two adiabatic invariants. Unfortunately, after over fifty years of study, decades-old disagreements remain about estimates of the intensity of this diffusion-like process, thus posing significant obstacles to the understanding and modeling of the dynamics of the radiation belts. In this presentation, we take a look at the radial diffusion process "under the microscope". Tracking the bounce-averaged motions of guiding centers, we examine the time variation of the third adiabatic invariant in the most general case, we reestablish the basics of radial diffusion, and we question commonly made assumptions in order to pave the way for a more accurate characterization of the process.