Sökning: "Auroral density cavity"

Hittade 3 avhandlingar innehållade orden Auroral density cavity.

  1. 1. Cluster investigations of the extent and altitude distribution of the auroral density cavity

    Författare :Love Alm; Göran T. Marklund; Tomas Karlsson; Rickard Lundin; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Auroral density cavity; auroral accelaration; Cluster; in situ observation; electron density; pseudo altitude; Physics; Fysik;

    Sammanfattning : The auroral density cavity constitutes the boundary between the cold, dense ionospheric plasma and the hot, tenuous plasma sheet plasma. The auroral density cavity is characterized by low electron density and particle populations modified by parallel electric fields. LÄS MER

  2. 2. Multi-Spacecraft Observations of the Auroral Acceleration Region

    Författare :Soheil Sadeghi; Göran T. Marklund; Andris Vaivads; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : The two major agents for producing aurora are generally believed to be the quasi-static parallel electric fields, accelerating electrons in the auroral acceleration region (AAR), and Alfvén waves. The Cluster spacecraft quartet has made multi-spacecraft measurements in the AAR possible for the first time. LÄS MER

  3. 3. Cluster in situ studies of the auroral acceleration region

    Författare :Bin Li; Göran Marklund; Stein Haaland; KTH; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Cluster; Aurora acceleration region; Physics; Fysik;

    Sammanfattning : This thesis addresses a central topic in auroral physics, namely particle accelerationproducing intense aurora as well as energetic plasma outflow. Cluster satellitemeasurements of electric and magnetic fields, electrons and ions, collected across auroralfield lines, are used to study various aspects of the quasi-static auroral accelerationregion (AAR), its relation to the auroral density cavity, and the relative role of quasistaticand Alfvénic acceleration for producing aurora. LÄS MER