The Laser Induced Cu Plasma Characteristics Under Space Constraints

In this paper, the laser induced breakdown spectroscopy is introduced firstly,then the basic principle of LIBS,research progress, applications fields and advantages are elaborated. Low sensitivity is one of the disadvantages of LIBS, so that the principle of the laser induced breakdown spectroscopy’s enhancement and the research status are introduced and analyzed. Researches on space constraints have been carried for years, due to the simple space constraints’ device, and obvious enhanced spectral effect. But many of them focused on the shape of the device space constraints, instead of how to improve the detection sensitivity of LIBS.As the device of space constraints, Al plates were used to constrain laser plasma. It was concluded that, the best effect of constraint can be got under the condition of 13.6J/cm2-energy-density and 10mm- plate- spacing, by the adjustment of laser’s energy density and plate spacing. As a result, the spectral intensity was increased by 3.9 times. After that, Changing the laser energy density while fixing the plate spacing at a level of 8mm, the research was carried on in the methods of spectral analysis, fast imaging and shadow imaging. A conclusion was drawn by analysis and comparison among spectral intensity, electron temperature, electron density and the letter back, that is the most obvious enhancement of spectral intensity and the best constraint effect can be made when the laser energy density is 13.6J/cm2. The mechanism of spectral enhancement, made by space constraints, was on full display, with a combination of plasma’s quick capture images and shock wave images at the same time delay. The other way around, similarly, changing the plate spacing while fixing the laser energy density at a level of 13.6J/cm2, it was found that the best constraint effect could be made when the plate spacing was 10 mm. Finally, the plasma’s quick capture images and shock waves’ shadow images became the direct proof of different effects on space constraints that different plate spacing had.Pass the data and images, the experiments above can observe and analyze the space constraints effect on the plasma directly, and also arrive at the mechanism of action of space constraints to plasma. It further confirms that spatial constraints can improve the detection sensitivity of LIBS, and an appropriate selection of laser energy density and plate spacing is important for the constraint effect.