Energized Heavy Ions and Magnetic Reconnection

Abstract:

Kinetic plasma simulations are used extensively to investigate he behavior of space plasmas in order to predict or explain observations made in-situ. This work uses a 2.5D explicit Particle-In-a-Cell (PIC) code to investigate the effects of energized heavy ions on reconnection. This work differs significantly from previous investigations involving heavy ions in that, here, they are energized as opposed to simply thermal, a significant variation based firmly on published in-situ measurements. Two populations of energized heavy ions are investigated. First an energized dawn-dusk stream of heavy ions along Speiser Orbits is introduced across the current sheet. Second an energized beam of outflow ions is introduced along field lines to the reconnection site. The evolution of each of these cases is compared to the evolution of otherwise identically configured systems having either no heavy ions or with a background of thermal heavy ions. Two main results are shown. First, the dawn-dusk streaming ions clearly produce a dramatic suppression of reconnection significantly delaying its onset. Second, the outflowing beam does not have a significant effect on the overall progression of the reconnection system but does cause a tail-ward skew in the structure. Most notably the ions did not exhibit the (traditionally expected) non-gyroscopic reflection at the x-line, producing a counter-streaming beam, but passed through the current sheet and out the opposite side.