Electron Kinetic Entropy across Quasi-Perpendicular Shocks

We use Magnetospheric Multiscale (MMS) data to study electron kinetic entropy per particle [Formula: see text] across Earth’s quasi-perpendicular bow shock. We have selected 22 shock crossings covering a wide range of shock conditions. Measured distribution functions are calibrated and corrected for spacecraft potential, secondary electron contamination, lack of measurements at the lowest energies and electron density measurements based on plasma frequency measurements. All crossings display an increase in electron kinetic entropy across the shock [Formula: see text] being positive or zero within their error margin. There is a strong dependence of [Formula: see text] on the change in electron temperature, [Formula: see text] , and the upstream electron plasma beta, [Formula: see text]. Shocks with large [Formula: see text] have large [Formula: see text]. Shocks with smaller [Formula: see text] are associated with larger [Formula: see text]. We use the values of [Formula: see text] , [Formula: see text] and density change [Formula: see text] to determine the effective adiabatic index of electrons for each shock crossing. The average effective adiabatic index is [Formula: see text].