Magnetic field effect on plasma parameters and surface modification of laser-irradiated Cu-alloy

The effect of magnetic field on the plasma parameters and surface modification of Cu-alloy has been investigated. For this purpose, we have employed Nd: YAG laser at various irradiances ranging from 1.9 to 5 GW/cm(2) to irradiate Cu-alloy under 5 torr pressure of argon, neon, and helium. The evaluated values of excitation temperature (T-exc) and electron number density (n(e)) of Cu-alloy plasma explored by laser-induced breakdown spectroscopy technique are higher in the presence of 1.1 Tesla magnetic field as compared with field-free case. It is true at all irradiances as well as under all environmental conditions. It is also found that trends of both T-exc and n(e) are increasing with increasing laser irradiance from 1.9 to 4.4 GW/cm(2). For the highest used irradiance 5 GW/cm(2), the decrease in both parameters is observed. The analytically calculated values of thermal beta, directional beta, confinement radius, and diffusion time for laser-irradiated Cu-alloy plasma confirm the validity of magnetic confinement. Scanning electron microscope analysis is utilized to study the surface modifications of laser-irradiated Cu samples and reveals the formation of islands, craters, cones, and droplets. The finer-scale surface structures are grown in case of magnetic. It is also revealed T-exc and n(e) play a substantial part in the growth of surface structures on Cu-alloy.