The role of cavity shape on spatially confined laser-induced breakdown spectroscopy

The influence of a columnar cavity with different shapes on laser-induced Cu plasma was investigated by optical emission spectroscopy. The circle, square, triangle, and bilateral cavities were used to confine the plasmas. The measured spectral lines were Cu (I) 510.5 nm, 515.3 nm, and 521.8 nm. An obvious enhancement in the emission intensity and plasma temperature was observed when the cavities with different shapes were used to confine the laser-induced Cu plasma. By comparing the spectral intensities under the cavities with different shapes, it was found that the emission intensity was the strongest and the plasma temperature was the highest under the spatial confinement with the cylindrical cavity. Therefore, the spatial confinement effect with the cylindrical cavity is the most appropriate. The spatial confinement effect is attributed to the plasma plume compressed by the reflected shock wave.