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- Laakso, H., Grard, R., Masson, A., Moullard, O., Bale, S., Mozer, F., Pedersen, A., Andre, M., Eriksson, A., Gustaffson, G. and Lindqvist, P.-A.
(författare)
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Multi-point electric field observations in the high-latitude magnetosphere
- 2001
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Ingår i: Les Woolliscroft Memorial Conference Sheffield Space Plasma Meeting: Multipoint Measurements versus Theory. Proceedings (SP-492) (2001) ESA SP-492. - : Noordwijk, Netherlands. ; , s. 27-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The authors use multi-point electric field observations from the four Cluster satellites to study the dynamical behavior of the high-latitude magnetosphere on February 13-14, 2001, 20-02 UT. At 20:00 UT the vehicles enter the cusp where three satellites o
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| 2. |
- Laakso, H., et al.
(författare)
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Multi-point electric field observations in the high-latitude magnetosphere
- 2001
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Ingår i: European Space Agency, (Special Publication) ESA SP. ; , s. 27-34
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Konferensbidrag (refereegranskat)abstract
- We use multi-point electric field observations from the four Cluster satellites to study the dynamical behavior of the high-latitude magnetosphere on February 13-14, 2001, 20-02 UT. At 20:00 UT the vehicles enter the cusp where three satellites observe a 500-volt potential drop. It implies that at lower altitudes there likely exist some parallel electric fields that accelerate electrons downward and ions upward. In the following 2-3 hours the satellites move over the southern polar cap where all four satellites pass through a number of stationary, large-scale density enhancements that are associated with 200-volt potential drops. The observed events are possibly ionospheric ion outflows, triggered by geomagnetic activity. At 23:20 UT, the satellites move in the distant plasma sheet, and an hour later they have a brief encounter with the auroral region where a density cavity of a few degrees wide is observed. At the equatorward edge of the cavity, large electric fields of 100 mV/m are observed, which are likely related to an auroral arc. Similar observations are collected from all four satellites within a few minutes, but a detailed comparison reveals plenty of differences, apparently due to small spatial and temporal scale sizes. Near the perigee pass, the vehicles traverse the plasma trough near local midnight, where they all detect a ULF wave event. A preliminary analysis of the event shows that it is a resonant mode of a 120-sec period. Surprisingly the observations from four satellites are not well correlated, which suggests a short spatial and temporal scale for the event. A possible source mechanism for ULF waves at this local time sector is drifting ring current protons.
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| 3. |
- Pedersen, A., Decreau, P., Escoubet, C.P., Gustafsson, G., Laakso, H., Lindqvist, P.-A. , Lybekk, B., Masson, A., Mozer, F. and Vaivads, A.
(författare)
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Four-point high time resolution information on electron densities by the electric field experiments (EFW) on Cluster.
- 2001
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Ingår i: Annales Geophysicae. ; 19:6, s. 1483-1489
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Tidskriftsartikel (refereegranskat)abstract
- For accurate measurements of electric fields spherical double probes are electronically controlled to be at a positive potential of approximately 1 volt relative to the ambient magnetospheric plasma. The spacecraft will acquire a potential which balance
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| 4. |
- Pedersen, A., et al.
(författare)
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Four-point high time resolution information on electron densities by the electric field experiments (EFW) on cluster
- 2001
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 19:12-okt, s. 1483-1489
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Tidskriftsartikel (refereegranskat)abstract
- For accurate measurements of electric fields, spherical double probes are electronically controlled to be at a positive potential of approximately 1 V relative to the ambient magnetospheric plasma. The spacecraft will acquire a potential which balances the photoelectrons escaping to the plasma and the electron flux collected from the plasma. The probe-to-plasma potential difference can be measured with a time resolution of a fraction of a second, and provides information on the electron density over a wide range of electron densities from the lobes (similar to0.01 cm(-3)) to the magnetosheath (> 10 cm(-3)) and the plasmasphere (> 100 cm(-3)). This technique has been perfected and calibrated against other density measurements on GEOS, ISEE-1, CRRES, GEOTAIL and POLAR. The Cluster spacecraft potential measurements opens the way for new approaches, particularly near boundaries and gradients where four-point measurements will provide information never obtained before. Another interesting point is that onboard data storage of this simple parameter can be done for complete orbits and thereby will provide background information for the shorter full data collection periods on Cluster. Preliminary calibrations against other density measurements on Cluster will be reported.
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