The terrestrial magnetosphere is a natural laboratory where many important plasma processes can be studied in detail by using high-quality spacecraft measurements of electromagnetic fields and particle distribution functions over a broad range of spatial and temporal scales. One such important process is magnetic reconnection. We discuss recent results on the detailed structure of reconnection sites, on suprathermal electron energization within reconnection regions and on reconnection within turbulent plasma. Particularly we demonstrate the importance of understanding in detail processes occurring at the characteristic ion and electron scales. Our results are based on multi-spacecraft observations by the Cluster spacecraft. We also briefly discuss the need for future multi-spacecraft missions, such as MMS and Cross-Scale, to further advance the understanding of magnetic reconnection. The results obtained by using spacecraft measurements can find direct applications to laboratory plasmas as well as to plasma environments around other planets, in the solar atmosphere and solar wind and in distant astrophysical objects.
Plasma energization through reconnection in a relativistic plasma