Formation of super-Alfvénic electron jets during laser-driven magnetic reconnection at the Shenguang-II facility: particle-in-cell simulations

Abstract

Magnetic reconnection experiments in high-energy-density (HED) laser-produced plasmas have recently been conducted at the Shenguang-II (SG-II) facility. Two plasma bubbles and a ‘frozen-in’ magnetic field are generated by irradiating an Al foil using two laser beams. As the two bubbles with opposing magnetic fields expand and squeeze each other, magnetic reconnection occurs. In the experiments, three well-collimated high-speed electron jets are observed in the fanlike outflow region of the laser-driven magnetic reconnection. Based on two-dimensional (2D) particle-in-cell (PIC) simulations, we demonstrate that the three electron jets in the outflow region of laser-driven magnetic reconnection are super-Alfvénic, and their formation mechanism is also revealed in this paper. The two super-Alfvénic jets at the edge are formed by the outflow electrons, which move along magnetic field lines after they are accelerated in the vicinity of the X-line by the reconnection electric field. The super-Alfvénic jet at the center is formed by the electrons that come from the outside of the plasma bubbles. These electrons are reflected by the magnetic field in the pileup region and are meanwhile accelerated by the resulting electric field.