Energetic electron fluxes at Saturn from Cassini observations

Energetic electron fluxes (18 keV–21 MeV) observed by the MIMI/LEMMS instrument on the Cassini mission during 2004 to 2008 are analyzed. We consider all 101 orbits and we select portions of the orbits that lie within 0.5 RS of the magnetic equatorial plane, where RS is Saturn's radius. We determine the average electron differential flux and integral flux at specified L‐shells in the range 4.5 < L < 11. Further, comparisons are made between the observed fluxes and the corresponding relativistic self‐limiting values developed from Kennel‐Petschek theory. We find that at lower L‐shells, L < 5, measured fluxes are much less than limiting values; at intermediate L‐shells, 5 < L < 7, measured fluxes are close to the Kennel‐Petschek limit; and at larger L‐shells, 7 < L < 10, measured fluxes well exceed the limit. This suggests that (1) at lower L‐shells particle injection is relatively weak, (2) at intermediate L‐shells, sufficiently strong particle injections generate whistler mode waves to self‐limit trapped fluxes, and (3) at larger L‐shells, intense particle injections result in trapped particle fluxes well in excess of the Kennel‐Petschek limit. Key Points Energetic electron fluxes during 2004 to 2008 are analyzed We determine the average electron differential and integral flux in 4.5 < L < 11 Comparisons are made between the observed fluxes and relativistic K‐P limits