| 1. |
- Boehm, M. H., et al.
(författare)
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Observations of an upward-directed electron beam with the perpendicular temperature of the cold ionosphere
- 1995
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 22, s. 2103-2106
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Tidskriftsartikel (refereegranskat)abstract
- The Freja TESP electron spectrometer has repeatedly observed similar to 100 eV - 1 keV upward-directed, anti-field-aligned electron beams near 1700 km altitude in the auroral zone. A particularly intense event, at energies up to 2 keV, is described. The beam perpendicular temperature T perpendicular to(e)), was as low as 0.1-0.2 eV at 100-200 eV parallel energy. The 10-15 s period of upward fluxes was coincident with a low density (similar to 10 cm(-3)) period and a similar to 5 keV ion conic. Strong low frequency waves and the lack of any downward motion in the simultaneously observed ion conic suggest a strong element of wave acceleration, while electric field and ion loss cone measurements provide limited evidence of potential acceleration to a fraction of the observed energies.
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| 2. |
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| 3. |
- 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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| 4. |
- 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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| 5. |
- Knudsen, DJ, et al.
(författare)
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Core ion flux bursts within solitary kinetic Alfven waves
- 1998
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 103:A3, s. 4157-4169
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Freja cold plasma analyzer (CPA) makes high time resolution measurements of the angle-and energy-integrated core ion velocity distribution (< 20 eV) with spatial resolutions of similar to 10 m. In a preliminary study, Knudsen et al. [1994] reported th
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| 6. |
- Knudsen, DJ, et al.
(författare)
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Correlation between core ion energization, suprathermal electron bursts, and broadband ELF plasma waves
- 1998
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. ; 103:A3, s. 4171-4186
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Observations of the lowest energy or core ions provide a particularly sensitive measure of the early stages of auroral ion energization. Freja satellite observations of 0-20 eV core ions in the topside auroral ionosphere and cusp/cleft show signs of heati
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| 7. |
- 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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| 8. |
- Seyler, CE, et al.
(författare)
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Theory of nearly perpendicular electrostatic plasma waves and comparison to Freja satellite observations
- 1996
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS. - : AMER GEOPHYSICAL UNION. - 0148-0227. ; 101:A10, s. 21795-21813
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The linear and nonlinear two-fluid nature of oblique electrostatic plasma waves is explored and clarified. It is found that two distinct wave regimes exist corresponding to propagation angles greater than or less than epsilon = root m(e)/m(i) with respect
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| 9. |
- 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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| 10. |
- Yamauchi, M, et al.
(författare)
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Acceleration signatures in the dayside boundary layer and the cusp
- 2001
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Ingår i: PHYSICS AND CHEMISTRY OF THE EARTH PART C-SOLAR-TERRESTIAL AND PLANETARY SCIENCE. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1464-1917. ; 26:1-3, s. 195-200 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- Freja data show various electron acceleration signatures in the cusp and the dayside boundary layer: (1) time dispersive suger-Alfvenic electrons followed by strong wave activity which accompanies transient downward super-thermal electron burst in both th
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