Published online by Cambridge University Press: 01 January 1992
Copper samples were ablated by a pico-second pulsed Nd:YAG laser in Ar and He gases under different pressures. At 1064 nm, the change of ablation rate of copper in He gas from lx10−5 to 760 torr is smaller than that in Ar gas. A model for the development of a plasma above the target surface is presented based on inverse Bremsstrahlung absorption between fast electrons and the gas medium. Ionization rate of the buffer gas versus pressure was estimated using the model, and a good correlation was found with the ablation rate.