1st Adiabatic Invariants and Phase Space Densities for the Jovian
Electron and Proton Radiation Belts-Galileo and GIRE3 Estimates
Abstract
The fluxes and phase space densities for a fixed 1st
adiabatic invariant for high energy electrons and protons provide
important inputs for various scientific studies for determining the
physics of particle diffusion and energization. This study provides
estimates of the 1st adiabatic invariant and phase
space density based on the complete and large data base available from
the Energetic Particle Detector (EPD) on Galileo for the jovian
environment. To be specific, 10 minute averages of the high energy
electron and proton data are used to compute differential flux spectra
versus energy for L=~8 - 25 over the Galileo mission.
These spectra provide estimates of the differential fluxes and phase
space density for constant 1st adiabatic invariants
between 102 to 105 MeV/G. As would
be expected, the electron and proton fluxes and phase space densities
generally trend lower as the planet is approached. The results indicate
that, whereas the overall trends for each orbit are consistent, detailed
orbit to orbit variations can be observed. Galileo orbit C22 is
presented as a specific example of deviations from the mean downward
trend. To validate the Galileo results and extend the findings into L=3,
the GIRE3 model was also used to compute the fluxes and phase space
densities for constant 1st adiabatic invariant versus
L-shell. Comparison between GIRE3 and EPD demonstrates that the model
adequately reproduces the EPD data trends and they consistently show
additional variations near Io. This provides proof that the GIRE3 is a
useful starting point for diffusion analyses and similar studies.