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Cassini observations of a Kelvin-Helmholtz vortex in Saturn's outer magnetosphere
Coates, A. J.; Krupp, N.; Dougherty, M. K. +9 more
We present Cassini observations of a plasma vortex in Saturn's dayside outer magnetosphere. The vortex encounter took place on 13 December 2004 as Cassini was travelling toward the planet. The spacecraft crossed the magnetopause 3 times, before being immersed in the low-latitude boundary layer. During the transition between the boundary layer and …
Heliospheric evolution of solar wind small-scale magnetic flux ropes
Moldwin, M. B.; Cartwright, M. L.
We present results from the first comprehensive small-scale flux rope survey between 0.3 and 5.5 AU using the Helios 1, Helios 2, IMP 8, Wind, ACE, and Ulysses spacecrafts to examine their occurrence rate, properties, and evolution. Small-scale flux ropes are similar to magnetic clouds and can be modeled as a constant-alpha, force-free, cylindrica…
Magnetospheric period oscillations at Saturn: Comparison of equatorial and high-latitude magnetic field periods with north and south Saturn kilometric radiation periods
Coates, A. J.; Dougherty, M. K.; Lamy, L. +4 more
It has recently been shown using Cassini radio data that Saturn kilometric radiation (SKR) emissions from the Northern and Southern hemispheres of Saturn are modulated at distinctly different periods, ∼10.6 h in the north and ∼10.8 h in the south, during the southern summer conditions that prevailed during the interval from 2004 to near-equinox in…
Influence of spacecraft outgassing on the exploration of tenuous atmospheres with in situ mass spectrometry
Wurz, P.; Altwegg, K.; Balsiger, H. +10 more
In situ mass spectrometry has been a powerful tool in many space missions to investigate atmospheres and exospheres of different bodies in the solar system. Applying new technologies, the mass spectrometers have become increasingly more sensitive. In this study, we show that spacecraft outgassing, which can never be completely prevented, will be t…
Cusp as a source for oxygen in the plasma sheet during geomagnetic storms
Dandouras, I.; Klecker, B.; Kistler, L. M. +1 more
We have used the ion composition data from the CIS/CODIF instrument on Cluster to determine how the O+ population in the plasma sheet and the adjacent lobes changes during geomagnetic storms. The Cluster trajectory, which moves over the polar cap, into the lobe, and then into the plasma sheet on each orbit, allows us to track the change…
Structure of magnetic separators and separator reconnection
Parnell, C. E.; Haynes, A. L.; Galsgaard, K.
Magnetic separators are important locations of three-dimensional magnetic reconnection. They are field lines that lie along the edges of four flux domains and represent the intersection of two separatrix surfaces. Since the intersection of two surfaces produces an X-type structure, when viewed along the line of intersection, the global three-dimen…
“Island surfing” mechanism of electron acceleration during magnetic reconnection
Fujimoto, M.; Phan, T. D.; Shinohara, I. +1 more
One of the key unresolved problems in the study of space plasmas is to explain the production of energetic electrons as magnetic field lines “reconnect” and release energy in an explosive manner. Recent observations suggest possible roles played by small-scale magnetic islands in the reconnection region, but their precise roles and the exact mecha…
Geomagnetic signatures of current wedge produced by fast flows in a plasma sheet
Dunlop, Malcolm; Zhang, Tielong; Cao, Jin-Bin +10 more
This paper uses the plasma data from Cluster and TC-1 and geomagnetic data to study the geomagnetic signatures of the current wedge produced by fast-flow braking in the plasma sheet. The three fast flows studied here occurred in a very quiet background and were accompanied by no (or weak) particle injections, thus avoiding the influences from othe…
Statistical study of O+ transport from the cusp to the lobes with Cluster CODIF data
Dandouras, I.; Klecker, B.; Kistler, L. M. +3 more
Ionospheric origin O+ accelerated in the cusp/cleft region convects over the polar cap and flows along open field lines to the tail lobes. Some O+ in the lobes enters the near-Earth plasma sheet where it is then convected to the inner magnetosphere, while some O+ ends up in the distant tail where it is lost. In ord…
Observations of energetic electrons up to 200 keV associated with a secondary island near the center of an ion diffusion region: A Cluster case study
Wang, Shui; Li, Xing; Huang, Can +2 more
An antiparallel reconnection event is recognized in the magnetotail, and a secondary island with a strong core magnetic field is identified near the center of the ion diffusion region. In the island, the electron density peaks in the outer region while the dip is in the core region with a strong core magnetic field. A strong electron beam parallel…