Doctoral Dissertations

Fall 1998

Dissertation

Physics

Degree Name

Doctor of Philosophy

The auroral current density-voltage and energy flux density-voltage relationships are derived under the assumption that magnetospheric electrons above the auroral acceleration region are described by the $\kappa$ distribution function. To illustrate the effects of this boundary condition on auroral precipitation, a two dimensional model of auroral electrodynamics similar to that of Lyons (1980) has been developed by imposing current continuity in the auroral zone. The current carried by precipitating magnetospheric electrons inside auroral arcs connects to return current regions at the arc edges via ionospheric Pedersen currents. A key feature is the ability to parameterize the magnetospheric boundary electron population as either a $\kappa$ or Maxwellian distribution. Clear differences emerge between these two distributions. The $\kappa$ distribution results predict up to double the peak auroral energy flux and as much as a 20-30% increase in the latitudinal width of the auroral energy flux as compared to the Maxwellian fit results. The width and intensity of the inverted V structures in the model results are found to be closely related to the level of thermal energy flux outside the inverted V.