Plasma heating and current sheet structure in anti-parallel magnetic reconnection

A theoretical model and an analytic theory of current sheet structure are presented for understanding anti-parallel driven magnetic reconnection in 2-1/2 dimension in collisionless plasmas. The theoretical model provides formulation to compute the current sheet y-profiles by specifying the profiles of electron and ion flow velocities V-ex (x, y ) and V-ix (x , y ). The current sheet solutions depend on the plasma density n(in), merging magnetic field B-0, ion velocity v(i), and electron velocity v(e) in the upstream and the S-evz = V-ez/V-dz parameter where V-ez is the electron velocity accelerated by the reconnection electric field E-z in the electron orbit meandering region, V-dz similar or equal to cE(y)/B-x is the (E) over right arrow x (B) over right arrow drift velocity as electrons enter the orbit meandering region, B-x is the merging magnetic field, and E-y is the electrostatic electric field. With simplifying assumptions on the y-profiles of V-ex and V-ix, we have also developed an analytic theory of the current sheet structure. Analytic expressions for the anomalous resistivity, the electrostatic potential drop, and the maximum E-y amplitude E-max are obtained. The analytic results agree reasonably well with both the particle-in-cell simulation results and the numerical solutions of the theoretical model. The ions energy gain due to the potential drop is proportional to B-0(2)/n(in). The electron energy gain is proportional to (B-0(2)/8 pi n(in)) S-evz. The B-0(2)/n(in) scaling of the average ion and electron energy gains are consistent with laboratory experiments and space plasma observations. (C) 2021 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

A theoretical model and analytic theory were developed to study anti-parallel driven magnetic reconnection in collisionless plasmas. Results show good agreement with experimental and observational data, providing insight into the current sheet structure in such systems.