气压对激光诱导Al等离子体特征的影响

使用Nd :YAG激光器烧蚀金属Al靶获得等离子体 ,利用光谱时 -空分辨技术 ,在 10 0～ 1× 10 5Pa气压范围内 ,关于环境气体压强对激光诱导的等离子体辐射特征的影响进行了研究。使用的气体是Ar气 ,单脉冲激光能量 145mJ。结果发现 ,气压升高 ,特征谱线强度增加 ,连续谱强度也增加 ;但气压过高 ,在接近大气压时 ,特征谱和连续谱都下降 ;最大特征辐射强度在 10kPa、靶前 0 .1mm处、延时 180ns获得 ;同一条件下获得最强背景连续谱 ,而信号 -背景比是在10 0 0Pa、靶前 1.0mm处、延时 2 50 0ns达到最大值。基于Al等离子体不同气压下的时间 -空间分辨谱 ,对结果进行了简单的讨论。并分别确定了获得最大特征辐射和信号 -背景比的条件 ;以及最佳信号采集区。

Effects of gas pressure on the emission characteristics of Aluminum plasma ablated with laser

The effects of ambient gas pressure on the emission characteristics of laser induced plasma were studied with a Q switched Nd:YAG laser over a pressure range of 100 Pa to 100 kPa in Argon atmosphere, During which time and space resolved spectroscopy was used. The laser energy was set up to 145 mJ. The experimental results showed that both the spectral lines and background increase with improvement of ambient pressure, but near 1 atmosphere, they decrease rapidly, the maximum spectral intensity occurred at about 10 kPa, 180 ns after laser beam shot, 0.1 mm from the surface. The background arrived the maximum at the same condition. Whereas the ratio of line to background reached maximum at 1 000 Pa, 2 500 ns, 1.0 mm from the surface. The results are discussed briefly on the basis of the time and space resolved spectra. The most favorite condition and the best zone of the plasma for data acquisition are suggested.