Plasma jet formation from laser ablation of thin aluminium film in a transverse magnetic field*

Plasma jets are often observed near accretion disks and in laser plasma experiments. We perform a 2D nonlinear MHD simulation to model the experimentally observed plasma jet formation following the laser ablation of a thin aluminium film in an external transverse magnetic field. In a recent experiment, the laser-ablated plasma can expand into a bubble structure both with and without an external magnetic field, and that a jet is formed at the top of the bubble only when there is an applied transverse magnetic field. The initial laser-produced plasma condition is prepared using the radiation-hydrodynamics code FLASH. The subsequent plasma evolution in an external magnetic transverse field is simulated using the initial-value MHD code NIMROD. We find that the plasma expansion is squeezed by the transverse magnetic field on both sides of the bubble to form a jet structure in the center, which may explain why in experiment the jet can only be observed in a transverse magnetic field. This may help understand the jet formation in both astrophysical and laboratory systems.