Laser Ablation: Beam Wavelength Optimization and Communication through Plasma

Laser ablation involves heating, evaporation of target material and ionization of vapor to form plasma plume surrounding the ablation spot. A self consistent model, that combines target heating, evaporation, ionization, shielding and expansion of plume, is employed to obtain ablation parameters. The results showed good agreement with experiments. For a given laser energy fluence and target material, major parameters of interest are depth of ablation and plasma shielding. These parameters are highly influenced by beam wavelength. A numerical study is carried out to obtain the optimum laser wavelength that maximizes the depth of ablation for three materials Al, Cu and Ti. Plasma prevents radio communication during testing of laser based directed energy systems. Possible mitigation approach using electrostatic sheath is analyzed. The influence of laser fluence, target material and background pressure on sheath characteristics is presented.