Monte‐Carlo Modeling of polar wind photoelectron distributions with anomalous heat flux

In situ measurements above the polar cap by the DE satellites show asymmetric, field‐aligned electron velocity distributions in the photoelectron energy range (5–60 eV). The formation of these anisotropic distributions is described by a collisional kinetic equation that includes the effects of Coulomb collisions (via a Fokker‐Planck operator), those of a parallel electric field, and the magnetic mirror effects of the geomagnetic field. We solve this equation using a Monte Carlo simulation method. The simulation illustrates the formation of the portion of the observed electron distributions originating in the ionosphere, and permits us to evaluate the significance of the suprathermal electrons at higher altitude. Both observations and calculations indicate that these electrons possess an energy flux which, by its effect on the polar wind electric field, may influence the dynamics of the polar wind outflow.