The Effect of External Magnetic Field on the Plasma Induced by Laser Ablation in Vacuum

During short-pulsed laser ablation (machining) process at sufficiently high intensities, a plasma plume may be generated above the target surface. In this paper, the effect of external magnetic fields on laser-induced plasma has been studied using a physics-based model. In the model, hydrodynamic equations coupled with wide-range equations of state are solved numerically using a finite-difference essentially non-oscillatory (ENO) method. The magnetic field affects the plasma evolution by inducing electric currents, and the associated electromagnetic force and Joule heating effect in the plasma. The study shows that the external magnetic field may decrease the plasma front expanding speed, and increase the plasma temperature. The study provides useful information for the fundamental study of laser-induced plasma, and for the practical applications of short-pulsed lasers in laser ablation (machining), laser-induced breakdown spectroscopy (LIBS), and other areas, where laser-induced plasma may play a very important role.