Particle Heating and Acceleration in the Diamagnetic Cavities*

Magnetic reconnection is a universal process which results in changes of magnetic topology as well as conversion of magnetic energy to thermal and kinetic energy of the plasma particles. However, the heating and particle acceleration that occurs close to reconnection diffusion regions at the dayside magnetopause is localized to a small area and thus cannot explain the ~ two orders of magntitude specific entropy increase observed when transitioning from shocked solar wind into the Earth's magnetopshere. Recent spacecraft observations have revealed that in the vicinity of cusp-like geometries magnetic reconnection can lead to formation of large-scale magnetic bottle structures (diamagnetic cavities, DMCs) where significant fluxes of electrons and ions can be trapped and energized to hundreds of keV energies. Since cusp-like structures are universal, occurring at planetary magnetospheres and close to surface of magnetized stars we are motivated to study the formation of these structures in laboratory plasma device, Big Red Ball (BRB), at University of Wisconsin Madison. This presenation will discuss the formation of DMCs and particle acceleration using multi-spacecraft observations and discuss the experimental setup at BRB. We calculate the minimum B-surface and express several quantities on this surface as well as characterize MMS observations of magnetic reconneciton and DMCs in terms of dimensionless parameters which will aid in comparison with experiments in BRB.