 |
| Titel |
The electron and the ion density characteristic near the F ring by Cassini/RPWS/LP |
| VerfasserIn |
Michiko Morooka, Jan-Erik Wahlund, David Andrews, Sheng-Yi Ye, William Kurth |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150376
|
| Publikation (Nr.) |
 EGU/EGU2017-14831.pdf |
|
|
|
|
|
| Zusammenfassung |
| Cassini observations revealed that there are a large amount of nm and μm sized dust grains
and their electrical interaction with the surrounding plasma near the moon Enceladus and the
E ring. In this region, the small grains are negatively charged by attaching the electrons,
resulting the unbalance in the ion and the electron densities (the ion density higher than the
electron density). Similar type observations are expected near the faint F and G ring
that are composed of small grains. During the grand finale, from December 2016,
Cassini has been orbiting Saturn with closest approach just outside the F ring. We
will show the electron and ion densities of those orbits obtained by the Langmuir
probe onboard Cassini (RPWS/LP). Preliminary results showed: 1) both the electron
and the ion density enhancement occurred near the equator (Z = ±0.5RS). 2) The
electron densities at the equator are about the order of 1 cm−3 (varies from 2 to 8),
while the ion densities are an order of magnitude larger than the electrons up to 300
cm−3. 3) The electron density depletion has been observed centered at the equator
around ±0.05 RS in Z. Coincide this region, the LP sweep current noise due to
the dust grain’s hitting the probe were observed. On the other hand, the peak of
the electron density seems to be located slightly northward above the equator at
∼0.05 RS. 4) One of the events showed a local electron density enhancement near
the L-shell at L = 3. The obtained characteristics are similar to what have been
found in the E ring near the Enceladus orbit. In the E ring, the electron density
enhancement region was centered at the equator in Z ±∼0.5RS, the electron bite out
occurred at Z = ±0.045RS, and the electron density peaks were somewhat higher in
the northern hemisphere. A possible explanation for the location differences in
the charged dust density peak and the plasma density peak can be due to that the
magnetic equator is located slightly north (+0.04RS) of the equator of the rings. We
plan to show the electron and the ion densities during the Cassini F ring campaign
and compare the results from the E ring as well as the density profiles along the
equator. |
|
|
|
|
|
|