Laser ablation of preheated copper samples

Abstract

A study of the effect of initial sample temperature on laser ablation of a copper sample at ambient air pressure by a 1064nm, 10ns laser pulse with energies of 11 and 15mJ (2.7–3.2GW∕cm2) is carried out. The sample is uniformly heated by a heating element up to 600K. Spectral emission of plasma is measured at different initial sample temperatures and delay times. Plasma temperatures are determined from the method of line pair ratio. The temperature profile inside the preheated target, ablation depth, thickness of dielectric, and melting layer are numerically computed by the finite difference method based on the phase explosion mechanism. Results show that an increase in the initial sample temperature leads to an increase in the spectral emission of plasma up to 90% which is attributed to both the plasma temperature and the ablated volume. Initial sample temperatures have no effects on background intensity of plasma emission. Thus, for spectroscopic purposes, the signal to noise ratio can be improved with initial sample temperature.