Satellite observations of auroral acceleration processes
1994 (English)Doctoral thesis, comprehensive summary (Other academic)
Measurements with satellite and sounding rocket borne instruments contain important information on remote and local processes in regions containing matter in the plasma state. The characteristic features of the particle distributions can be used to explain the morphology and dynamics of the different plasma populations. Charged particles are lost from a region due to precipitation into the atmosphere, charge exchange processes, or convection to open magnetic field lines. The sources of the Earth’s magnetospheric plasma are mainly ionization and extraction of upper atmosphere constituents, and entry of solar wind plasma. The intensity and distribution of auroral precipitation is controlled in part by the conditions of the interplanetary magnetic field causing different levels of auroral activity. Acceleration of electrons and positive ions along auroral field lines play an important role in magnetospheric physics. Electric fields that are quasi-steady during particle transit times, as well as fluctuating fields, are important for our understanding of the behaviour of the plasma in the auroral region. High-resolution data from the Swedish Viking and the Swedish/German Freja satellites have increased our knowledge considerably about the interaction processes between different particle populations and between particles and wave fields. This thesis describes acceleration processes influencing both ions and electrons and is based on in-situ measurements in the auroral acceleration/heating region, with special emphasis on; processes at very high latitudes, the role of fluctuating electric fields in producing so called electron conics, and positive ion heating transverse to the geomagnetic field lines.
Place, publisher, year, edition, pages
Umeå: Umeå universitet , 1994. , 31 p.
IRF Scientific Report, ISSN 0284-1703 ; 217
Aurora, particle acceleration, space plasma, magnetosphere, ionosphere, polar cap, satellite observations
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:umu:diva-102339ISBN: 91-7174-926-8OAI: oai:DiVA.org:umu-102339DiVA: diva2:808724
1994-09-16, konferensrummet Aniara, Institutet för rymdfysik i Kiruna, Kiruna, 10:15
Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 6 uppsatser.2015-04-302015-04-232015-04-30Bibliographically approved