Measurements of Parallel Electric Fields during Guide Field Reconnection in Laboratory and Space Plasmas

The parallel electric field is important in magnetic reconnection regions as it is a primary mechanism of energy conversion by directly accelerating electrons. Furthermore, it is important to understand how large parallel electric fields can be sustained in collisionless and weakly collisional plasmas in order to obtain fast rates of magnetic reconnection. We present an experimental comparison study of plasma and field profiles by the MMS and from the Magnetic Reconnection eXperiment (MRX), from a recent set of experiments conducted with a guide field. The MRX experiment enables large ensemble averages, and high accuracy and resolution measurements. We make the first detailed laboratory measurements and quantitative analysis of the quadrupolar electron pressure variation over the ion- diffusion region, as originally predicted by extended MHD simulations of guide field reconnection. We observed that the projection of the electron pressure gradient parallel to the magnetic field contributes significantly to balancing the parallel electric field. These results will be compared with recent MMS current sheet crossing in guide field regimes, including parallel electric fields.