1. Energetic charged particle injections at Saturn C. Paranicas 1, D. G. Mitchell 1, D. C. Hamilton 2, S. M. Krimigis 1, B. H. Mauk 1, P. C. Brandt 1, J. F. Carbary 1, A. M. Rymer 1, A. Mueller 3 (1) Johns Hopkins Univ/APL (2) University of Maryland (3) Max Planck/Sonnensystemforschung Fall AGU San Francisco, CA 16 December 2008

2. Overview For our purposes, injections are any non- azimuthally-symmetric populations that are higher in flux than ambient particles Our main goal is to continue to study injection phenomena to create a picture of transport/acceleration that is appropriate to what is observed in energetic charged particle data We will also show occurrence statistics of these features in the Cassini/MIMI data obtained at Saturn

3. Picture of the transport In the classical picture of interchange, flux tubes with hotter, less dense plasma move inward and take the place of flux tubes with colder, denser plasma But in many instances of plasma physics, the flux tube concept breaks down.

4. In this example, it appears that flux tubes filled with energetic protons are displacing the ambient particles (data from MIMI/CHEMS: All 3 telescopes included). Injections

5. This section of the previous plot includes CHEMS/Telescope-2 only, measuring particles with near 90 o pitch angle (Cassini is near Saturn’s equator at this time)

6. This is a section of the plot including data from CHEMS/Telescope-1 only. Here it does not appear that a separate flux tube is displacing the background particles (during this time, T-1 is detecting particles with pitch angles of about 45 o ). Remnants of a previous proton injection that are dispersed

7. Another view of these injections from the MIMI/LEMMS sensor

8. Transport/acceleration In CHEMS/T-2 and LEMMS, the data seem to show the spacecraft on flux tubes containing newly injected particles only In telescopes 1 and 3, it appears that the spacecraft is on flux tubes that simultaneously contain new injecting distributions and older dispersed injections that join seamlessly with the surrounding medium

9. A second example showing a dispersed injection detected at the same position by Cassini as new injections at lower energy

10. Occurrence statistics To study whether the various types of injections have common properties, we surveyed the near equatorial injections observed by Cassini/MIMI Here we consider only very recent injections that have not had sufficient time to disperse in energy Previously, the plasma injections detected by Cassini was surveyed in this manner (e.g. Hill et al. 2005)

11. Distribution of plasma injections At the plasma energies, injections appear to be initiated at all local times and longitudes From Hill et al. (2005):

12. Proton injections by local time, Cassini coverage While the recent injections in this survey appear to cluster around noon and midnight local time, this is also where Cassini has taken data

13. Recent proton injections: in L and SKR longitude

14. Recent electron injections by L and SKR longitude

15. Discussion We are still considering mechanisms of acceleration and transport for the various injections observed by MIMI This preliminary work does not suggest strong organization of recent injections by LT, longitude, or SKR longitude

16. Extras

18. Proton injections time vs SKR