Spatial Characteristics of Spectral Intensity of Laser Induced Plasma

Laser wavelength and incident angle arc important factors that influence the spatial distribution and spectral intensity of laser-induced plasma. Based on the fluid dynamics and SAHA equation, this paper simulates the two-dimensional spatial distribution of laser-induced plasma, calculates the spatial distribution of radiation spectrum of the excited plasma, and studies the influences of laser incident angle, wavelength and other parameters on the spatial distribution characteristics of plasma characteristic spectral lines. The research results show that that 0 is the best incident angle for 1061 nm laser with different delay conditions. When the incident angle is 0, the excited plasma radiation has stronger spectral signals at different detection angles. Moreover, the optimal detection angles arc +/- 41 degrees, +/- 11 degrees, and +/- 12 degrees at 100 ns, 500 ns and 1000 ns delay conditions, respectively. For different wavelengths, when the delay time is 100 ns or 500 ns and the laser is incident at 0 degrees, the intensity of plasma spectrum excited by 1064 nm laser at each detection angle is stronger compared that by a short wavelength laser. When the time delay is 100 ns, the intensity of the plasma spectrum excited by the 1064 nm laser at the optimal detection angle is approximately twice that by 532 nm or 266 nm laser at each optimal detection angle. With the decrease of the absolute value of the detection angle, the spectral intensity of the plasma radiation first increases and then decreases at the optimal detection angle. The simulation results arc verified by the laser induced breakdown spectroscopy experimental results with incident wavelengths of 532 nm and 1064 nm, respectively.