Using satellite data to calculate entropy of electrons at collisionless shocks

Sammanfattning: The solar wind is a supersonic flow of protons and electrons emitted in all directions from the sun. As the supersonic solar wind encounters Earth’s magnetic field, it creates the Earth’s bow shock, which increases the kinetic entropy of electrons passing through it. In this study, the aim is to analyze shock crossings of Earth’s bow shock in order to draw conclusions of which shock parameters that are important forkinetic entropy generation. Due to knowledge gained from an earlier study by M. Lindberg et al. [1], the shock crossings of interest in this study are quasi-perpendicular shocks with a low electron plasma beta. The data used is measured with the NASA MMS spacecraft and accessed through IRF Uppsala. As a result,a database with 13 shock crossings was created and the entropy change was related to, among other parameters, temperature and density change, shock angle, Alfv´en Mach number, ion ram pressure and upstream magnetic field. We found that a highAlfv´en Mach number related nearly proportionally to a large change in electron entropy for low electron plasma beta quasiperpendicularcollisionless shock crossing.