为深入了解激光诱导击穿光谱技术应用于复合肥成分的检测机制， 选用不同物理形态（粉状和颗粒状）的复合肥样品， 在不同压力下制得片状样品进行实验， 以分析不同物理形态复合肥样品的激光诱导击穿光谱特性。 实验分别对比了0， 0.5， 2， 4， 6 MPa下粉末和颗粒的N， P， K的等离子体光谱特性。 研究结果表明， 在压力较小时， 两种形态样品的光谱特性存在较大差别， 且颗粒状样品的谱线强度明显高于粉末状样品。 而随着压力的增加， 两者的光谱特性的差别逐渐减小。 对于同一形态样品， 随着压力的增加， 各主要元素的特征谱线强度均呈现先增加后减小的变化趋势。

In order to study the mechanism of laser-induced breakdown spectroscopy for detecting the chemical components content of compound fertilizer in detail, two physical forms of compound fertilizer samples (powder and granular) were used for this study. The authors analyzed the laser-induced breakdown spectroscopy properties of samples with different physical forms made under different preparation pressure. And the spectral characteristics and plasma characteristics of N，P and K in the powder and granules made under the preparation pressure of 0, 0.5, 2, 4, and 6 MPa, respectively were compared experimentally. The experiments results showed that the spectral characteristics of the two forms have obvious difference when the pressure is small and the grain samples have significant higher line intensity than those of the powder samples. With the increase in the pressure, the difference in the plasma characteristics between these two physical forms was reduced, and all the characteristic spectral lines intensity of the same physical form samples increases firstly and reduces afterward.