HR: 1330h
AN: SM13A-02    [Abstracts]
TI: The Compton Getting effect in ENA images of energetic ion injections at Saturn
AU: * Paranicas, C
EM: chris.paranicas@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Mitchell, D G
EM: Donald.G.Mitchell@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Roelof, E C
EM: Edmond.C.Roelof@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Brandt, P C
EM: Pontus.C.Brandt@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Williams, D
EM: Donald.Williams@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Mauk, B H
EM: Barry.Mauk@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AU: Krimigis, S M
EM: Stamatios.M.Krimigis@jhuapl.edu
AF: Applied Physics Laboratory, MS MP3-E128 11100 Johns Hopkins Rd., Laurel, MD 20723 United States
AB: The Cassini Ion and Neutral Camera (INCA) images local energetic ion populations and energetic neutral atoms (ENAs). During the final months of approach to Saturn, INCA frequently imaged the whole Saturnian magnetosphere. Data from that period reveal an intermittent signal in total ENA flux, sometimes near our detector background. After closest approach, INCA images from orbit frequently show intense brightenings confined in local time. We have interpreted these signals as localized bursts of injected ions which then corotate with the planet. Often the injection related component of the ENAs is more intense than all the ENA emission from the rest of the magnetosphere. We suspect that the strongest ENA signals detected on approach were likely due to similar injection events. We have further observed that the ENAs created by the injected population seem to be brightest in the midnight sector. We have demonstrated that this is due primarily to the Compton-Getting effect, which for the detection of energetic ions in a flowing plasma gives higher counts in the sectors viewing into the oncoming flow. The relative distance between the spacecraft and the injected population will also affect the total ENA counts in an INCA image because of the R^-2 dependence from the source distribution. Unlike ENA imaging at Earth (where corotation velocities are about 5% of those at the same L value in Saturn's magnetosphere), the Compton-Getting effect is essential to the interpretation of ENA images of the rapidly rotating magnetospheres of the giant planets.
DE: 2730 Magnetosphere--inner
DE: 2756 Planetary magnetospheres (5443, 5737, 6030)
DE: 5737 Magnetospheres (2756)
DE: 6275 Saturn
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly