Distribution of escaping ions produced by non‐specular reflection at the stationary quasi‐perpendicular shock front

Field‐aligned and gyrophase bunched ion beams are observed in the foreshock of the Earth bow shock. One of the mechanisms proposed for their production is non‐specular reflection at the shock front. We study the distributions which are formed at the stationary quasi‐perpendicular shock front within the same process which is responsible for the generation of reflected ions and transmitted gyrating ions. The test particle motion analysis in a model shock allows one to identify the parameters which control the efficiency of the process and the features of the escaping ion distribution. These parameters are: the angle between the shock normal and the upstream magnetic field, the ratio of the ion thermal velocity to the flow velocity upstream, and the cross‐shock potential. A typical distribution of escaping ions exhibits a bimodal pitch angle distribution (in the plasma rest frame).