First direct experimental evidence of the merging of two colliding field reversed configurations

Abstract

The collisional merging of two Alfvénic-speed translated field reversed configurations (FRCs) via magnetic reconnection is presented with a two-dimensional magnetic probe array in the KMAX-FRC experiment. The collision is accompanied by axial compression and radial expansion, resulting in the increase in the FRC’s current density and poloidal flux. A reversed-current sheet is found to form during collision, indicating the occurrence of magnetic reconnection. After merging, the ion and electron temperature are increased. By comparing three different scenarios, i.e., the single-translated FRC, the FRC colliding solely with a stream plasma, and the collisional-merging FRC, we identify that axial compression and magnetic reconnection both contribute the electron heating.