Hall physics during magnetic reconnection with collision effect

The Hall effect, decoupling between the ion and electron motions, is the core mechanism triggering fast reconnection. In plasmas with collision effects such as laboratory facilities, collision can suppress the Hall effect and influence the triggering of fast reconnection. Here, by conducting a series of kinetic simulations with varying collision parameters, we show that collisions can suppress the electron outflow, impairing the quadrupole Hall magnetic field. Besides, collision weakens the inflow of magnetic flux by reducing the charge separation and increasing the thermal pressure at the reconnection site, leading to a reduction of the Hall electric field. As the collisionality becomes larger, the Hall electric field diminishes more easily than the Hall magnetic field. We propose that the quadrupolar Hall magnetic field can be a significant indicator in reflecting Hall reconnection.