The Impact of Shock Dynamic and Structure on Ion Reflection at the Quasi-Perpendicular Earths Bow Shock

Cluster observations revealed new insights into the ion reflection and the formation of field-aligned beam at quasi-perpendicular Earths bow shock. It appears that beam ions emerge from the gyrating ions in the ramp of a quasi-perpendicular shock created by the same reflection process. In fact, effective scattering in pitch angle within the shock ramp during the reflection seem to be the production mechanism. Ion reflection, transmission and wave particle scattering depends on shock parameters, such as Mach number, plasma beta and shock angle. These processes may also depend on the internal dynamic structure and the cross-shock potential. All these parameters appear to control ion reflection at the shock and escape of ions into the upstream region, but their relative importance for the distribution of gyrating ions and for the ion beam intensity is still unknown. A better understanding will lead us to new models of ion reflection and transmission processes at perpendicular shocks in general: stationary and interplanetary traveling shocks. We combined FGM, EFW and CIS data to investigate the effect of particle scattering, cross-shock potential, and plasma parameters on the reflection properties of the quasi-perpendicular bow shock. Furthermore, we included the shock dynamics into a selected set of bow shock crossings in which we correlate the intensity the gyrating and the beam ions relative to the solar wind flux. We compared these flux values obtained under certain plasma conditions to determine the main controlling parameters for low and high Mach number shocks. We will also discuss these results within the framework of existing models and theories.