M. Walt, S. Lev-Tov, H. D. Voss, J Mobilia, and J-M. Jahn
High resolution pitch angle distributions of 150 keV to 400 keV
trapped protons obtained by the CEPPAD/SEPS spectrometer on the NASA POLAR
satellite are analyzed to study the magnitude of pitch angle diffusion and
L-shell diffusion. Two magnetically quiet times were selected, the first
on August 5, 1998, following an extended period of low Kp and Dst. At
this time the proton belt was stationary, allowing a balance between
diffusion sources and charge exchange losses. A magnetic storm began on
August 6 with Dst of
-165 nT. On August 11 to 13 magnetic activity was again low, but enhanced
proton fluxes injected during the storm of August 6 were still present.
The observed decay rates of the proton fluxes were compared with expected
charge exchange losses and diffusion source terms. During both of these
magnetically quiet times the pitch angle scattering and L-shell diffusion
rates were much smaller than expected.
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