Magnetospheric Multiscale Statistics of High Energy Electrons Trapped in Diamagnetic Cavities

摘要

High-energy electrons observed in the magnetosheath must be accelerated by some mechanism that is as yet undetermined. We present observations of high-energy electrons trapped in diamagnetic cavities as measured by Magnetospheric Multiscale from 2015 to 2018. The observations support the notion of local acceleration in the reconnection quasi-potential as many of events show particles with pitch angles that are increasingly closer to 90° with increasing energy. It is suggested that these particles can end up in the loss cone and be transported to the magnetosheath. We also characterize each diamagnetic cavity as formed due to low- or high-latitude reconnection based on prevailing solar wind conditions. The character of the ions in the diamagnetic cavity is only briefly mentioned as their properties warrant another stand-alone investigation.