Currents in reconnection plasma jets: comparative study of laboratory experiments and spacecraft observations

Abstract

Magnetic reconnection is a universal plasma process that has been observed in various space plasma systems and reproduced well in laboratory simulations. During reconnection, magnetic field energy is transformed into energy of fast plasma flows that propagate away from the reconnection site. The leading front of these flows is the primary interface where energies are exchanged between flows and ambient plasmas. One of the most investigated fronts is the so-called dipolarization front in the Earth’s magnetotail. This study is devoted to a thorough comparison of the current systems associated with dipolarization fronts and fronts of fast plasma flows in laboratory experiments. We show that in both systems the plasma flow front is characterized by inverse currents, which deform the magnetic field configuration of the front. Laboratory experiments further show that such inverse currents may contribute to the plasma flow breaking; we also discuss their implications for the magnetotail plasma, where a similar mechanism for plasma flow breaking is likely operating.