Research on the mechanism of magnetic field enhancement of nanosecond laser-induced plasma cleaning of 7075 aluminum alloy surface paint layer

This paper innovatively proposes a magnetic field-assisted nanosecond laser cleaning technology. It addresses the issues that occur during nanosecond laser cleaning of the surface aviation paint layer of 7075 aluminum alloy, such as the thermal damage to the substrate and the poor cleaning uniformity. By constructing a theoretical model that couples heat conduction, magnetohydrodynamics (MHD), and spectral diagnosis, combined with experiments and molecular dynamics simulations, the physical mechanism of magnetic field regulation of laser-induced plasma to optimize the cleaning process is revealed. The study shows that the transverse magnetic field, through the Lorentz force to confine the plasma plume, significantly enhances the plasma temperature and electron density, strengthens the plasma and the secondary thermal-mechanical coupling effect on the paint layer. Molecular dynamics simulations reveal the microscopic process of the paint layer detaching through the reduction of interface adsorption energy, internal swelling, and stress-driven crack propagation at the interface. This research provides important theoretical and technological basis for the high-precision and low-damage green cleaning of aerospace aluminum alloy components.