激光脉冲能量对激光诱导Al等离子体辐射特征的影响

Effects of laser pulse energy on the emission characteristics of aluminum plasma ablated with laser

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 52mJ～145mL/pulse激光脉冲能量范围内 ,关于激光脉冲能量对激光诱导等离子体辐射特征的影响进行了研究。使用的气体是Ar气 ,压强为 10kPa。结果发现 ,激光脉冲能量升高 ,引起特征谱线强度增加 ,连续谱强度也增加 ;但能量过高 ,会击穿周围气体 ,产生气体微等离子体。此时 ,特征谱和连续谱几乎不再增强 ;最大特征辐射强度在 145mJ、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 背景差是在 145mJ、10kPa、靶前 1.0mm处、延时 4 50ns达到最大值。基于Al等离子体不同激光脉冲能量下的时间 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 背景差的条件。

The effects of laser pulse energy on the emission characteristics of laser induced plasma were studied with a Q switched Nd:YAG laser over an energy range of 52 mJ to 145 mJ in Argon atmosphere, During which time and space resolved spectroscopy was used. The ambient gas pressure was set up to 10 kPa. The experimental results showed that both the spectral lines and background increase with improvement of laser pulse energy, but the increment of spectra lines and background are not evident when the laser pulse energy increase high enough to cause Ar to breakdown and form an Ar microplasma, the maximum spectral intensity occurred at about 10 kPa, 180 ns after laser beam shot, 0.1 mm from the surface, with the laser pulse energy 145mJ. The background arrived the maximum at the same condition. Whereas the difference between line and background reached maximum at about 10 kPa, 450 ns after laser beam shot, 1.0 mm from the surface, with the laser pulse energy 145 mJ. The results are discussed briefly on the basis of the time and space resolved spectra. The most favorite condition for data acquisition is suggested.