Evolution of laser-produced plasma in an external magnetic field

Abstract

The evolution of laser-produced plasma in an external magnetic field was studied. Equations of ideal MHD in a cylindrical coordinate system were solved numerically by using the conservative TVD difference scheme of second order in time and space. At the beginning, a short 30-ns laser pulse with the Gaussian transverse intensity distribution with a half-width of 0.03 cm was applied to heat the target that consisted of aluminum vapor plasma. The cases of weak (plasma parameter β = 1) and strong (β = 0.026) external magnetic fields were considered. The results of the numerical calculations show that the magnetic field increases the width of the laser plume’s front and forces plasma to move predominantly along the magnetic field lines. An increase of the magnetic field strength resulted in increased inhomogeneity of temperature and density distributions in the laser plume volume. The model shows that in the final stages of evolution the laser plasma takes the form of a confined jet aligned along the symmetry axis.