考察了大气环境下激光诱导击穿光谱适用于煤粉流多元素同时检测的激光能量范围, 分析了造成煤粉流测量谱线信号波动的原因, 得到了适用于煤粉流多元素同时检测的激发区域功率密度范围和最佳功率密度。 实验选取能量范围为20～160 mJ, 粒径小于200 μm煤粉颗粒经下料口自由下落形成煤粉流束, 通过螺杆式给粉机控制流量, 波长1 064 nm脉冲激光聚焦后作用于下降的煤粉流束上, 产生等离子体, 光谱仪采集等离子体发射光谱信号, 分析结果表明: 实验台架下适于煤粉流LIBS检测的能量范围为30～60 mJ, 对应激发前沿功率密度选取范围14.4～34.4 GW·cm-2, 最佳测量功率密度19.5 GW·cm-2。

The logical range of laser power density and optimum laser power density were explored for multi-element analysis of pulverized coal flow with laser-induced breakdown spectroscopy in the present paper. The range of laser energy was chosen from 20 to 160 mJ in the experiment. Pulverized coal less than 200 μm in diameter of particles fell freely through feeder outlet and the rate of flow was controlled by screw feeder. Emissions were collected with pulse laser at 1 064 nm focusing on pulverized coal flow and plasma was generated. The intensity and cause of fluctuation of emission spectra at various laser energy levels were studied. A suitable range of laser power density is from 14.4 to 34.4 GW·cm-2, and the optimum laser power density is 19.5 GW·cm-2 for the determination of pulverized coal flow with LIBS.