| 1. |
- Blomberg, Lars, et al.
(författare)
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Viking observations of electric fields
- 1992
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Ingår i: Study of the Solar-Terrestrial System. ; , s. 269-274
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
- DUBOULOZ, N, et al.
(författare)
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DETAILED ANALYSIS OF BROAD-BAND ELECTROSTATIC NOISE IN THE DAYSIDE AURORAL-ZONE
- 1991
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - SWEDISH INST SPACE PHYS,S-75590 UPPSALA,SWEDEN. ROYAL INST TECHNOL,S-10044 STOCKHOLM 70,SWEDEN.. - 0148-0227. ; 96:A3, s. 3565-3579
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Tidskriftsartikel (refereegranskat)abstract
- The great number of bursts of broadband electrostatic noise (BEN) recorded during crossings of the dayside auroral zone by the Viking satellite enables their statistical study. The angular distribution of BEN with respect to the Earth's magnetic field is shown to be most likely isotropic, implying that it cannot consist of a unique linear plasma mode. Most of the bursts evidence a power law spectrum from the lower hybrid and ion plasma frequencies up to frequencies sometimes much higher than the electron plasma frequency, suggesting the presence of nonlinear effects. This is confirmed by their high intensity, and by the correlation between their amplitude and their frequency extension. BEN emissions are associated with ion conical distributions and with field-aligned electron beams. Although most of the power is concentrated at very low frequencies and around the lower hybrid and ion plasma frequencies, electron acoustic and beam mode waves may contribute to the high-frequency extension of BEN. The most intense BEN emissions are also correlated with sharp cold plasma density gradients and probably involve drift instabilities. Strong quasi-static perpendicular electric fields, which induce high-speed plasma flows, are also measured, so that the Doppler effect may contribute to the broadening of the BEN spectrum.
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| 3. |
- Feldstein, Y. I., et al.
(författare)
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Electromagnetic weather at 100 km altitude on 3 August 1986
- 1994
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 21, s. 2095-2098
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Tidskriftsartikel (refereegranskat)abstract
- The electromagnetic weather at high altitudes above the Earth’s surface is determined by the transport of ionospheric plasma, which in turn is governed by the magnitude as well as the direction of the electric and magnetic fields. Different models [Levitin et al., 1984; Friis-Christensen et al., 1985; Mishin, 1990] have been proposed that allow an estimation of the electromagnetic parameters of the upper atmosphere, given a knowledge of the magnitude and orientation of the interplanetary magnetic field. Here we use one such model to estimate the global convection pattern and its temporal evolution during a pass of the Swedish satellite Viking over the northern polar cap. The model predictions are shown to agree well with the electric and magnetic fields measured along the satellite trajectory. The good agreement implies that the model can be used to reconstruct, with reasonable confidence, the large-scale distribution of electric and magnetic fields and their time-variation in the entire auroral ionosphere.
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| 4. |
- HULTQVIST, B, et al.
(författare)
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ON THE UPWARD ACCELERATION OF ELECTRONS AND IONS BY LOW-FREQUENCY ELECTRIC-FIELD FLUCTUATIONS OBSERVED BY VIKING
- 1991
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : American Geophysical Union (AGU). - 0148-0227. ; 96:A7, s. 11609-11615
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Tidskriftsartikel (refereegranskat)abstract
- The dependence of the generation of upward electron beams in the to side ionosphere on the amplitude of the slow electric field fluctuations and the magnitude of the dc potential difference in the acceleration region is found to agree with the model involving the fluctuating electric field component presented in 1988 by Hultqvist. The ratio between the amplitude of the electric field fluctuations, E(f), determined by the dipole electric field experiment, and the dc acceleration voltage V(acc), given by the energy of the upflowing ion beam, is much higher on average for satellite spins showing an upward electron beam than for the spins without. It is also shown that low plasma density favors the generation of electron beams.
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| 5. |
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| 6. |
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| 7. |
- KLETZING, CA, et al.
(författare)
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Electric-fields derived from electron-drift measurements
- 1994
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Ingår i: GEOPHYSICAL RESEARCH LETTERS. - : American Geophysical Union (AGU). - 0094-8276. ; 21:17, s. 1863-1866
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Tidskriftsartikel (refereegranskat)abstract
- The first observations of electric fields derived from electron E x B drift measurements aboard the Freja spacecraft are presented. The instrument injects a weak beam of 3 keV electrons and measures the displacement of the returning electrons after one gyroperiod. After removing effects due to beam-detector geometry and applying an empirical calibration based upon comparison with the computed v x B electric field induced by the spacecraft motion, good agreement is found when the electron drift measurements are compared with the electric field components measured by the double probe experiment. Examples are presented in which moderately large electric fields are observed near the edges of or adjacent to electron precipitation regions with little or no electric field within.
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