• Ion dynamics in auroral potential structures and formation of ion conic distribution

      Yang, Wei-hong (1981-12)
      This thesis is concerned with the problem of how the positive ions are energized by the two-dimensional potential structures along auroral field lines; these auroral potential structures are known to be responsible for accelerating electrons into the ionosphere to produce discrete auroras. A systematic numerical study of the test ion dynamics in auroral potential structures, either V-shaped or S-shaped, has been carried out. Transverse ion accelerations occur if the width of the auroral potential structure (Lx ≤ ρi). This result shows that the conic distribution of upstreaming ions observed on auroral field lines can be generated by the same potential structures which produce the thin auroral arcs (Lx ≤ ρi). This transverse acceleration mechanism operates more effectively on heavier ions, resulting in O+ ions more energetic than H+ ions as indicated by observations.