Characteristics of Electron Density in Ablation Plasma Generated from Functionally Graded Material in Excimer Laser Processing

Functionally graded materials (FGMs), which possess the dual characteristics of two materials, are expected to be useful in industry in the near future. It is important to find a process of laser ablation when laser is used in the reprocessing of FGM such as cutting and drilling. The electron density is one of the important parameters needed to analyze the mechanism of the ablation plasma. The characteristics of electron density in ablation plasma were estimated. A XeCl excimer laser with a wavelength of 308 nm, a maximum pulse energy of 500 mJ and a pulse duration of 30 ns was used. A Mach-Zehnder interferometer was used to measure the electron density. The electron density dependence of the ablation plasma plumes on the ceramic-metal content of FGMs was observed. The temporal and spatial profiles of the electron density were also observed.