采用Nd∶YAG 脉冲激光器输出单脉冲序列激光重复作用于土壤样品表面同一位置使其形成熔穴，由光栅光谱仪和ICCD 采集每个激光序列脉冲的等离子体发射光谱，研究了激光诱导熔穴对土壤样品等离子体辐射特性的影响。实验结果显示，在熔穴的约束作用下，Cr和Pb 元素的谱线强度和信背比都随激光序列脉冲个数的增加呈先增大后减小的变化趋势；熔穴约束的最佳尺寸为直径1.0 mm、深度2.5 mm。随着激光脉冲个数的增加，FeⅠ422.64 nm自吸程度逐渐降低直至消失。研究结果表明，在熔穴孔径的约束作用下，谱线强度和信背比大幅提高，等离子体电子温度升高，有效地降低了谱线的自吸程度。

Single pulses exported from Nd: YAG laser are used to act on the same position of soil sample surface repeatedly to form laser- induced craters. Grating spectrometer and ICCD are used to record plasma emission spectra generated from each laser pulse. The effect of laser-induced craters on radiation characteristics of soil plasma is investigated. The experimental results show that there exists a trend that the line intensity and signalto- background ratio of Cr and Pb elements initially increase and then decrease along with increased number of laser shots under the confinement effect of crater walls. Overall, the best signal intensity can be obtained with a confinement laser-induced crater with 1.0 mm diameter and 2.5 mm depth. The experiment clearly indicates that self-absorption becomes weaker and then disappears along with increased number of laser shots. The results show that the line intensity and signal-to-background ratio are both improved and the electron temperature increases under the confinement effect of the crater walls, reducing the level of self-absorption spectral lines effectively.