Discharge character and optical emission in a laser ablation nanosecond discharge enhanced silicon plasma

Nanosecond discharge enhanced laser-induced breakdown spectroscopy of silicon was investigated. An intense discharge spark was observed with a peak discharge current of 1.63 kA and a peak power of 8.1 MW, and only lasted for similar to 51 ns. The discharge stability and the effect of the capacitances on the discharge and optical emission were investigated. A stable discharge process and optical emission were observed. The precision in terms of the relative standard deviation (RSD) of time delay between the laser firing and discharge was 1.7% with a discharge voltage of 9 kV, while the RSD of line intensities from repeatable measurements was typically about 2-3%. The measured line intensities of atomic and ionic states of silicon were used for electron temperature calculation by employing Saha-Boltzmann plots. Electron number density was determined by using the Stark broadening of two silicon atomic lines. Compared to the laser induced plasma, the temperature of the discharge enhanced plasma was increased, while the electron number density in the discharge plasma was roughly the same in the laser ablation nanosecond discharge enhanced Si plasma.