Numerical simulation on the formation and merging of ablation plasma in two exploding aluminum wires

In this paper, computational results characterizing the formation and merging of counter-streaming interpenetrating plasma flows formed in exploding double parallel aluminum wires are presented. A radial magnetohydrodynamic computation is carried out first to obtain the parameters of core-corona structure in individual wires, providing an initial condition for the planar magnetohydrodynamic model in a multi-species fluids scheme with two-temperature treatment of plasma. In the XY plane, two aluminum plasma clouds are surrounded by extremely thin air, which represents a vacuum environment. A long-lasting compressed layer of extremely thin air in the central region of the inter-wire gap is formed before the merger of aluminum plasma flows. The accordance between the increasing mass fraction of aluminum plasma species in the central slit and the enhancement in self-emission light demonstrates that the real physical characteristics of extremely low-density vacuum environment plays an important role in merger of aluminum plasma flows. Current density is concentrated in the central column during the merging process of counter-streaming interpenetrating aluminum plasma flows, evolving from a structure of bifurcated current sheets into a single narrow sheet. Efficient numerical investigation on the interaction between counter-streaming plasma flows requires the incorporation of surrounding fluid species of extremely thin air. (paper)