| 1. |
- 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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| 2. |
- Boström, R., Eriksson, A.I., Åhlén, L., Blomberg, L., Gustafsson, G., Holback, B., Holmgren, G., Holtet, J., Jansson, S.E., Lindqvist, P.A., Lybekk, B., Mälkki, A., Riihelä, P. and Wahlund, J.E.
(författare)
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The Rosetta Dual Langmuir Probe Instrument for Measurements of Plasma Density, Temperature and Flow Velocity.
- 2001
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Ingår i: ESA SP-1165.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Gustafsson, G, et al.
(författare)
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The electric field and wave experiment for the Cluster mission
- 1997
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Ingår i: Space Science Reviews. - 0038-6308 .- 1572-9672. ; 79, s. 137-156
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Tidskriftsartikel (refereegranskat)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and temperature. The instrument has several important capabilities. These include (1) measurements of quasi-static electric fields of amplitudes lip to 700 mV m(-1) with high amplitude and time resolution, (2) measurements over short periods of time of up to five simualtaneous waveforms (two electric signals and three magnetic signals from the seach coil magnetometer sensors) of a bandwidth of 4 kHz with high time resolution, (3) measurements of density fluctuations in four points with high time resolution. Among the more interesting scientific objectives of the experiment are studies of nonlinear wave phenomena that result in acceleration of plasma as well as large- and small-scale interferometric measurements. By using four spacecraft for large-scale differential measurements and several Langmuir probes on one spacecraft for small-scale interferometry, it will be possible to study motion and shape of plasma structures on a wide range of spatial and temporal scales. This paper describes the primary scientific objectives of the EFW experiment and the technical capabilities of the instrument.
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| 4. |
- Pecseli, HL, et al.
(författare)
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Lower hybrid wave cavities detected by the FREJA satellite
- 1996
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 101:A3, s. 5299-5316
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Localized electrostatic wave packets in the frequency region of lower hybrid waves have been detected by the instruments on the FREJA satellite. These waves are often associated with local density depletions indicating that the structures can be interpret
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| 5. |
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| 6. |
- Dovner, PO, et al.
(författare)
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The occurrence of lower hybrid cavities in the upper ionosphere
- 1997
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Ingår i: GEOPHYSICAL RESEARCH LETTERS. - : AMER GEOPHYSICAL UNION. - 0094-8276. ; 24:5, s. 619-622
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Lower hybrid cavities (LHC), i. e., small-scale density depletions coinciding with enhanced lower hybrid waves, are frequent in the upper ionosphere. It is found that they exist in all regions the Freja satellite has scanned, as long as lower hybrid waves
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| 7. |
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| 8. |
- Gustafsson, G, et al.
(författare)
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The electric field and wave experiment for the Cluster mission
- 1997
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Ingår i: SPACE SCIENCE REVIEWS. - : KLUWER ACADEMIC PUBL. - 0038-6308. ; 79:1-2, s. 137-156
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Tidskriftsartikel (refereegranskat)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and tempera
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| 9. |
- Holback, B, et al.
(författare)
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LINDA - the Astrid-2 Langmuir probe instrument
- 2001
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Ingår i: ANNALES GEOPHYSICAE. - : EUROPEAN GEOPHYSICAL SOCIETY. - 0992-7689. ; 19:6, s. 601-610
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish micro-satellite Astrid-2, designed for studies in magnetosperic physics, was launched into orbit on 10 December 1998 from the Russian cosmodrome Plesetsk. It was injected into a circular orbit at 1000 km and at 83 degrees inclination. The sate
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| 10. |
- HOLBACK, B, et al.
(författare)
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THE FREJA WAVE AND PLASMA-DENSITY EXPERIMENT
- 1994
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Ingår i: SPACE SCIENCE REVIEWS. - : KLUWER ACADEMIC PUBL. ; 70:3-4, s. 577-592
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- The Wave Experiment, F4, on the Swedish/German satellite Freja, is designed to measure the electric wave fields up to 4 MHz, the magnetic wave fields up to 16 kHz and the plasma density and its relative variations up to 2 kHz. Six wave signals and four de
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| 11. |
- Huang, GI, et al.
(författare)
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Nonlinear plasma oscillation with a fractional harmonics and analysis in the time-frequency spectrum
- 1997
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Ingår i: CHINESE PHYSICS LETTERS. - : ALLERTON PRESS INC. - 0256-307X. ; 14:11, s. 857-860
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the observations of Freja satellite in the energization legion of the low aurora(1700km), a new nonlinear plasma oscillation with a turbulent spectrum at the fractional harmonics of the local proton gyrofrequencies is reported and analyzed with the wav
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| 12. |
- Huang, GL, et al.
(författare)
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The eigenmode of solitary kinetic Alfven waves observed by Freja satellite
- 1997
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 102:A4, s. 7217-7224
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The properties of the solitary kinetic Alfven waves (SKAWs) observed by Freja satellite are studied statistically for a typical event on March 7, 1994. The eigenmode of the SKAWs observed is still recognized by their anisotropic structure (1000 km x 1 km)
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| 13. |
- Ivchenko, N, et al.
(författare)
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Disturbance of plasma environment in the vicinity of the Astrid-2 microsatellite
- 2001
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Ingår i: ANNALES GEOPHYSICAE. - : EUROPEAN GEOPHYSICAL SOCIETY. - 0992-7689. ; 19:6, s. 655-666
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Tidskriftsartikel (refereegranskat)abstract
- The presence of a satellite disturbs the ambient plasma. The charging of the spacecraft creates a sheath around it, and the motion of the satellite creates a wake disturbance. This modification of the plasma environment introduces difficulties in measurin
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| 14. |
- Ivchenko, Nickolay V., et al.
(författare)
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Disturbance of plasma environment in the vicinity of the Astrid-2 microsatellite
- 2001
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 19:6, s. 655-666
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Tidskriftsartikel (refereegranskat)abstract
- The presence of a satellite disturbs the ambient plasma. The charging of the spacecraft creates a sheath around it, and the motion of the satellite creates a wake disturbance. This modification of the plasma environment introduces difficulties in measuring electric fields and plasma densities using the probe technique. We present a study of the structure of the sheath and wake around the Astrid-2 microsatellite, as observed by the probes of the EMMA and LINDA instruments, Measurements with biased LINDA probes, as well as current sweeps on the EMMA probes, show a density enhancement upstream of the satellite and a plasma depletion behind the satellite. The electric field probes detect disturbances in the plasma potential on magnetic field lines connected to the satellite.
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| 15. |
- KINTNER, PM, et al.
(författare)
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FIRST RESULTS FROM THE FREJA HF SNAPSHOT RECEIVER
- 1995
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Ingår i: GEOPHYSICAL RESEARCH LETTERS. - : AMER GEOPHYSICAL UNION. - 0094-8276. ; 22:3, s. 287-290
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Freja plasma wave instrument has measured electric field waveforms up to 4 MHz in the auroral ionosphere near 1700 km altitude. The HF snapshot receiver responds to natural signals during every passage through the auroral ionosphere and we have curren
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| 16. |
- Makela, JS, et al.
(författare)
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Evolution of mesoscale auroral cavities before substorm onset
- 1999
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 104:A8, s. 17201-17215
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have used density measurements made by the Freja satellite to analyze the dynamical behavior of mesoscale auroral cavities at an altitude of 1700 km. Freja's orbital period of 109 min enabled a very large data set of cavity occurrences to be collected.
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| 17. |
- Makela, JS, et al.
(författare)
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Observations of mesoscale auroral plasma cavity crossings with the Freja satellite
- 1998
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 103:A5, s. 9391-9404
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have used data from the Freja satellite, with an apogee of 1700 km over the auroral oval, to make a statistical analysis of mesoscale auroral plasma density cavities. Such cavities are defined to be regions in the auroral zone with size scales between
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| 18. |
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| 19. |
- SEYLER, CE, et al.
(författare)
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THEORY AND SIMULATION OF LOW-FREQUENCY PLASMA-WAVES AND COMPARISON TO FREJA SATELLITE-OBSERVATIONS
- 1995
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 100:A11, s. 21453-21472
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- One-dimensional models of obliquely propagating nonlinear plasma waves were formulated and solved both analytically and numerically to interpret recent Freja satellite observations of low-frequency plasma waves detected in the low-altitude auroral magneto
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| 20. |
- Stasiewicz, K, et al.
(författare)
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Parametric instabilities of Langmuir waves observed by Freja
- 1996
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 101:A10, s. 21515-21525
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Tidskriftsartikel (refereegranskat)abstract
- We have analyzed complete spectrum of waves (0-4 MHz) and electron distributions during events of modulated Langmuir waves observed by Freja in the topside polar ionosphere. Modulated Langmuir waves are observed with amplitudes 1-1000 mV/m in association
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| 21. |
- Volwerk, M, et al.
(författare)
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Solitary kinetic Alfven waves: A study of the Poynting flux
- 1996
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 101:A6, s. 13335-13343
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Using a particular mode of the FREJA wave experiment (three magnetic and one electric simultaneous measurements), we have investigated the electromagnetic structure of the solitary kinetic Alfven waves observed in the topside ionosphere, It is shown that
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| 22. |
- Wahlund, JE, et al.
(författare)
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Broadband ELF plasma emission during auroral energization 1. Slow ion acoustic waves
- 1998
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 103:A3, s. 4343-4375
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- High-resolution measurements by the Freja spacecraft of broadband extremely low frequency (BB-ELF) emission from de up to the lower hybrid frequency (a few kHz) are reported from regions of transverse ion acceleration (TAI) and broad-energy suprathermal e
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