Current Layer Width Scaling in the Terrestrial Reconnection Experiment vs. Collisionless Simulations*

PIC simulations of magnetic reconnection at varying collisionality show that the out-of-plane current layer of the reconnection region becomes thinner and longer as the collisionality decreases [1].  While prior reconnection experiments have disagreed with this result [2], in 2017 the Terrestrial Reconnection Experiment (TREX) measured out-of-plane current layer widths that compared favorably with simulation results over a variety of ion species and reconnecting field strengths.  Building on these findings, the 2018 run of TREX investigated similar plasmas with an improved diagnostic suite, measuring the current layers and other magnetic structures in even finer detail.  In conjunction with this experimental effort, the newly developed cylindrical VPIC code from Los Alamos National Laboratory is being used to simulate the cylindrical TREX configuration.  The findings from this latest experimental run and these new simulations will presented and compared.

[1] Le, A. et al. JPP, 81(1). doi: 10.1017/S0022377814000907.

[2] Ji, H. et al. Geophys. Res. Lett., 35, L13106. doi:10.1029/2008GL034538.