Study On Near-infrared Spectra Of Pulsed Laser-induced Aluminum Plasma

Laser-induced plasma is an important source of electromagnetic wave radiation,and its radiation range includes extreme ultraviolet,ultraviolet,visible,infrared,terahertz to microwave band.Laser-induced breakdown spectroscopy(LIBS)is a technology developed on the basis of this spectral radiation source.This technology can analyze the element composition and content of solid,liquid and gas samples.LIBS technology has been widely used in industrial production,food safety,environmental protection,material analysis,archeological relics,space exploration and other fields.With the continuous development of laser and spectrum detector technology,LIBS technology has also made great progress.However,the traditional LIBS technology still needs to be supplemented and optimized.Therefore,it is necessary to carry out infrared spectrum research.In this paper,aluminum materials are used as experimental targets.Single-pulse and double-pulse laser-induced breakdown infrared spectroscopy experiments are performed by setting up experimental devices,which mainly include the following:1.The effects of different experimental parameters(pulse laser energy,gas pressure,laser wavelength,and distance from the focusing lens to the surface of the target)on the infrared radiation characteristics of the plasma were analyzed in depth by building a single-pulse experimental device.The experimental results show that changing any one of the experimental parameters alone will have an effect on the infrared spectrum of the plasma,and that the different experimental parameters have different effects on the experimental results.We also performed a plasma morphology change experiment that changed the distance from the focusing lens to the target surface,and further explored the experimental results.2.A double-pulse laser-induced plasma infrared radiation experimental device was set up,and experiments were performed using nanosecond pulse lasers with wavelengths of 1064 nm and 532 nm.The experimental results show that under different pressure conditions,the double-pulse spectrum is enhanced compared to the single-pulse spectrum,and the enhancement effect is most obvious under atmospheric pressure,which is 10.44 times stronger.Then we changed the characteristics of the dual-pulse laser-induced plasma infrared spectrum by changing different experimental parameters(ambient gas pressure,inter-pulse delay,and energy allocation relationship between pulses).Finally,we summarized the experimental results and prospected the follow-up work.