3D Simulations of Reconnection Spreading Between Non-Parallel Flux Ropes in the WVU PHASMA Experiment

Magnetic flux ropes are columns of plasma with axial and azimuthal magnetic fields and are commonly observed on the Sun and in the terrestrial magnetosphere. Two flux ropes are created with pulsed plasma guns in the West Virginia University PHAse Space MApping (PHASMA) experiment. The flux ropes are fixed in space at one end (the plasma gun end) and the other end of the ropes terminates on a conical anode. By varying the angle of the cone, the boundary condition is variable from line-tied (fixed) to non-line-tied (free). The conical anode introduces a small degree of tilt between the two flux ropes. In the experiment, the flux ropes are observed to rotate around each other, merge, and bounce during which magnetic energy is released via the process of magnetic reconnection. Here, we present simulation results from the 3D electron-magnetohydrodynamics (EMHD) code F3D of reconnecting flux ropes tilted at an angle, motivated by the experiment. We find reconnection spreads sequentially in a zipper-like fashion starting where the flux ropes are initially closest and cascading along the axial direction to where the flux ropes began further apart. We perform a parametric study as a function of flux rope axial current, axial magnetic field, and boundary conditions (line-tied and non-line-tied) and compare them to the laboratory observations.