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| 2. |
- 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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| 3. |
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| 4. |
- Mella, M. R., et al.
(författare)
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Sounding rocket study of two sequential auroral poleward boundary intensifications
- 2011
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. A00K18-
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Tidskriftsartikel (refereegranskat)abstract
- The Cascades-2 sounding rocket was launched on 20 March 2009 at 11: 04: 00 UT from the Poker Flat Research Range in Alaska, and flew across a series of poleward boundary intensifications (PBIs). The rocket initially crosses a diffuse arc, then crosses the equatorward extent of one PBI (a streamer), and finally crosses the initiation of a separate PBI before entering the polar cap. Each of the crossings have fundamentally different in situ electron energy and pitch angle structure, and different ground optics images of visible aurora. It is found that the diffuse arc has a quasi-static acceleration mechanism, and the intensification at the poleward boundary has an Alfvenic acceleration mechanism. The streamer shows characteristics of both types of acceleration. PFISR data provide ionospheric context for the rocket observations. Three THEMIS satellites in close conjunction with the rocket foot point show earthward flows and slight dipolarizations in the magnetotail associated with the in situ observations of PBI activity. An important goal of the Cascades-2 study is to bring together the different observational communities (rocket, ground cameras, ground radar, satellite) with the same case study. The Cascades-2 experiment is the first sounding rocket observation of a PBI sequence, enabling a detailed investigation of the electron signatures and optical aurora associated with various stages of a PBI sequence as it evolves from an Alfvenic to a more quasi-static structure.
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| 5. |
- 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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