Study of the plasma dynamic response mechanism of Q235 steel under magnetic field-assisted combined laser irradiation

This study investigates magnetic field-assisted combined laser irradiation of Q235 steel, constructing a two-dimensional coupled simulation model integrating the two-temperature model and magnetohydrodynamics, to explore the intrinsic mechanisms of plasma evolution and surface morphology reconstruction under the synergistic effect of magnetic field and combined laser. The results show that magnetic field control induces oscillations in laminar velocity and suppresses plasma expansion. The Lorentz force effectively constrains the plasma, enhancing its aggregation, and shrinking the emission region, thereby increasing local energy density and enhancing detection sensitivity. The coupling effect of the magnetic field and laser drives the flow field to transition to vortex flow, promoting reactant mixing and heat transfer. The magnetic field enhances the plasma spectral response, increasing spectral line intensity and the number of characteristic peaks, while also elevating the electron temperature and driving the electron density to a plateau. The magnetic field enhances plasma mass transfer, buffering combustion wave recoil damage, optimizing solidification behavior in the remelted zone, and controlling surface roughness.