Plasma fluctuations and large‐scale mixing near comet Giacobini‐Zinner
作者:
D. N. Baker,
W. C. Feldman,
S. P. Gary,
D. J. McComas,
J. Middleditch,
期刊:
Geophysical Research Letters
(WILEY Available online 1986)
卷期:
Volume 13,
issue 3
页码: 271-274
ISSN:0094-8276
年代: 1986
DOI:10.1029/GL013i003p00271
数据来源: WILEY
摘要:
Low‐pass filtered data from the ICE electron spectrometer are used to examine relationships between plasma densities, flow speeds, flow directions, and temperatures at distances within ∼105km of the Comet Giacobini‐Zinner nucleus. The sheath/transition region is characterized by electron temperatures of ∼4 × 105K but with flow speeds and densities that commonly vary by factors of three or more. The largest amplitude density spikes often have significant flow changes associated with them, but a consistent pattern (as might accompany cometary rays, for example) is not found. Power spectral analyses in and near the sheath/transition regions show that density fluctuation levels are enhanced at all detectable frequencies from ∼0 to 21 mHz, consistent with strong density fluctuations on all measured time scales. Marginally significant power peaks are seen at periods of ∼4 min on the inbound pass and at ∼2 min on the outbound pass. Mechanisms such as amplification of convected ion pick‐up waves and cometary rays for producing the large plasma variations are discussed. It is also suggested that a Rayleigh‐Taylor driven mixing mechanism at a mass loading boundary ∼105km from the nucl
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