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DOI | 10.1029/2018GL078137 |
Saturn's Plasma Density Depletions Along Magnetic Field Lines Connected to the Main Rings | |
Farrell, W. M.1; Hadid, L. Z.2; Morooka, M. W.2; Kurth, W. S.3; Wahlund, J. -E.2; MacDowall, R. J.1; Sulaiman, A. H.3; Persoon, A. M.3; Gurnett, D. A.3 | |
2018-08-28 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS
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ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2018 |
卷号 | 45期号:16页码:8104-8110 |
文章类型 | Article |
语种 | 英语 |
国家 | USA; Sweden |
英文摘要 | We report on a set of clear and abrupt decreases in the high-frequency boundary of whistler mode emissions detected by Cassini at high latitudes (about +/- 40 degrees) during the low-altitude proximal flybys of Saturn. These abrupt decreases or dropouts have start and stop locations that correspond to L shells at the edges of the A and B rings. Langmuir probe measurements can confirm, in some cases, that the abrupt decrease in the high-frequency whistler mode boundary is associated with a corresponding abrupt electron density dropout over evacuated field lines connected to the A and B rings. Wideband data also reveal electron plasma oscillations and whistler mode cutoffs consistent with a low-density plasma in the region. The observation of the electron density dropout along ring-connecting field lines suggests that strong ambipolar forces are operating, drawing cold ionospheric ions outward to fill the flux tubes. There is an analog with the refilling of flux tubes in the terrestrial plasmasphere. We suggest that the ring-connected electron density dropouts observed between 1.1 and 1.3 R-s are connected to the low-density ring plasma cavity observed overtop the A and B rings during the 2004 Saturn orbital insertion pass. Plain Language Summary We present Cassini observations during the close passes by the planet Saturn indicating that plasma on magnetic field lines that pass through the A and B rings is of anomalously low density. These observations are consistent with the Saturn orbit insertion observations of a plasma cavity located at equatorial regions overtop the dense B ring. Using a terrestrial analogy, we suggest that the low-density conditions overtop the rings create an electrical force, called an ambipolar electric field that draws plasma out of the ionosphere in an attempt to replenish the plasma void found at equatorial regions. |
英文关键词 | Saturn Cassini rings plasma |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000445612500026 |
WOS关键词 | MAGNETOSPHERE ; IONOSPHERE ; ENVIRONMENT ; ENCELADUS ; RADIO ; ORBIT |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/26031 |
专题 | 气候变化 |
作者单位 | 1.NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA; 2.Swedish Inst Space Phys, Uppsala, Sweden; 3.Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA |
推荐引用方式 GB/T 7714 | Farrell, W. M.,Hadid, L. Z.,Morooka, M. W.,et al. Saturn's Plasma Density Depletions Along Magnetic Field Lines Connected to the Main Rings[J]. GEOPHYSICAL RESEARCH LETTERS,2018,45(16):8104-8110. |
APA | Farrell, W. M..,Hadid, L. Z..,Morooka, M. W..,Kurth, W. S..,Wahlund, J. -E..,...&Gurnett, D. A..(2018).Saturn's Plasma Density Depletions Along Magnetic Field Lines Connected to the Main Rings.GEOPHYSICAL RESEARCH LETTERS,45(16),8104-8110. |
MLA | Farrell, W. M.,et al."Saturn's Plasma Density Depletions Along Magnetic Field Lines Connected to the Main Rings".GEOPHYSICAL RESEARCH LETTERS 45.16(2018):8104-8110. |
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