Energy deposition in metals by laser-guided discharges

Abstract

Experimental and theoretical results are reported concerning energy deposition on metal surfaces by laser-guided discharges (LGD) in argon and nitrogen at atmospheric pressure. These experiments have demonstrated effective guidance of 30-kV discharges for lengths up to 6 cm. The electron temperature and density have been measured spectroscopically for LGD plasmas. Scaling of the melted metallic mass has been studied as a function of discharge circuit parameters for both argon and nitrogen. Results show that laser-guided discharges in nitrogen couple energy to metal samples more efficiently than argon discharges with identical electrical parameters. This experimentally observed difference in energy deposition has been shown to be in good agreement with a theoretical model which accounts for the recombination energy of nitrogen on the metallic surface. Melting has been accomplished by LGDs in copper, iron, aluminum, and titanium foils. Laser-guided discharges have also bored holes and deposited surface layers of aluminum and titanium onto stainless steel.