为了提高激光诱导击穿光谱质量, 采用Nd∶YAG激光器输出的纳秒脉冲激光激发产生土壤等离子体, 采用光栅光谱仪和光电检测系统记录了元素谱线AlⅠ394.401 nm, BaⅠ455.403 nm, FeⅠ430.791 nm和TiⅠ498.173 nm的辐射强度和信背比, 研究了激光脉冲重复频率（5, 10和15 Hz）对等离子体辐射特性的影响。 实验结果表明, 在相同的激光输出能量条件下, 当采用15 Hz的激光脉冲重复频率时, 元素Al, Ba, Fe和Ti的谱线强度要比5 Hz时的分别提高50.94%, 112.7%, 107.46%和99.38%, 光谱信背比分别提高15.16%, 24.08%, 40.26%和72.06%。 通过测量等离子体参数, 解释了激光脉冲重复频率对等离子体辐射特性的影响机理。

To improve the quality of laser-induced breakdown spectroscopy, nanosecond pulse laser generated by Nd∶YAG laser was used to excite soil sample. The intensity and signal-to-background ratio of Al Ⅰ 394.401 nm, Ba Ⅰ 455.403 nm, Fe Ⅰ 430.791 nm and Ti Ⅰ 498.173 nm were observed using a grating spectrometer and a photoelectric detection system. The effects of laser shot frequency（5, 10 and 15 Hz）on the radiation characteristics of laser-induced plasma was studied. The experimental results show that as compared with the laser shot frequency of 5 Hz, the spectral line intensity of Al, Ba, Fe and Ti increased by about 50.94%, 112.7%, 107.46%, and 99.38% at 15 Hz respectively under the same laser energy, while the spectral signal-to-background ratio increased byabout 15.16%, 24.08%, 40.26% and 72.06% respectively. The effects mechanism of the laser shot frequency on radiation characteristics of plasma is explained by measuring plasma parameters.