Spectroscopy and Spectral Analysis, Volume. 36, Issue 3, 817(2016)
Research on Temporal and Spatial Evolution of Reheating Double-Pulse Laser-Induced Plasma
In order to investigate the emission enhancement mechanisms of reheating Double Pulse Laser-Induced Breakdown Spectroscopy (DP-LIBS), single pulse LIBS (SP-LIBS) and reheating DP-LIBS were carried out on an alloy steel sample respectively. The plasma emission was collected by an Echelle spectrometer with high resolution, while the plasma structure was monitored via fast-photography. The temporal and spatial evolutio ns of the plasma generated by SP-LIBS and reheating DP-LIBS were being studied. It is found that the plasma temperature in reheating DP-LIBS was higher than that of SP-LIBS, and there was a turning point for the decay rate of plasma temperature in reheating DP-LIBS when the delay time was equal to the inter-pulse time of DP-LIBS. Moreover, the inte nsity of the plasma image was increased by reheating DP-LIBS, and the height and width of the central region of the plasma were increased about 23.5% and 15.1% respectively. The results of spatial distribution showed that the inte nsity of Fe Ⅱ and N I lines in the plasma were obviously enhanced by reheating DP-LIBS when the distance from the sample surface was larger than 0.6 mm. While the inte nsity enhancement for Fe Ⅰ lines were little, even in some positio ns the inte nsity of Fe Ⅰ lines decreased. The plasma temperature of double-pulse configuration was about 2 000 K higher than that of SP-LIBS, and a larger hot region in the plasma was generated. It is evidenced that the emission enhancement mechanisms in reheating DP-LIBS is that the second laser pulse re-excited the plasma induced by the first laser pulse, and the higher plasma temperature resulted from the re-exciting process.
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WANG Jing-ge, FU Hong-bo, NI Zhi-bo, HE Wen-gan, CHEN Xing-long, DONG Feng-zhong. Research on Temporal and Spatial Evolution of Reheating Double-Pulse Laser-Induced Plasma[J]. Spectroscopy and Spectral Analysis, 2016, 36(3): 817
Received: Apr. 15, 2014
Accepted: --
Published Online: Dec. 9, 2016
The Author Email: Jing-ge WANG (xiaogezi_1987@163.com)