Effects of oblique double layers on upgoing ion pitch angle and gyrophase

Observations of electrostatic shocks above the auroral zone, of upgoing ion beams that show evidence of both parallel and perpendicular acceleration, and of ion conics suggest that the shocks play a role in the energization of the beams and, perhaps, of certain conics. To investigate shock effects on ions, I follow the trajectories of many ions through a very simple model of an oblique double layer, a narrow region of strong electric field with components both parallel and perpendicular to the magnetic field. Acceleration through the model oblique double layer produces gyrophase bunching, and hence density oscillations. Although it arises from a model that is not self‐consistent, this result shows that a consistent oblique double layer model must include temporal variations and/or spatial oscillations in the density or electric field. The oblique double layer increases both the perpendicular and the parallel energy of ions. The amount of perpendicular energization is greater for O+ than for H+, in agreement with observations. I examine the parametric dependence of perpendicular energization on initial ion enery, the angle between the electric and magnetic field, and the width of the potential structure.