The Influence Of Matrix Temperature On The Spectral Signal Of Laser-induced Plasma

Laser Induced Breakdown Spectroscopy(LIBS)is an element diagnostic tool that can provide distinct spectral signatures characteristic of all chemical species with the advantage of remotely,in-situ,online and no sample pretreatment.LIBS has been regarded as “a future superstar” for chemical analysis,and has been applied to many fields successfully.It was found that raising the matrix temperature can enhance the spectral intensity of LIBS,but the mechanism of the effect of matrix temperature on laser induced plasma is unclear.LIBS technology has unparalleled advantages applied in some extreme and complex environments,mostly ?sed for online monitoring.For example,in the field of variable temperature environments such as alloy smelting and additive manufacturing,LIBS technology can be ?sed for online monitoring element the segregation and impurities introduction.Therefore,it has a great significance for LIBS online application to investigate the influence of matrix temperature on LIBS.In this thesis,the effects of tungsten-molybdenum matrix temperature on LIBS had been investigated in air,argon and vacuum environments,and the ablated craters on the alloy surface of different temperature were characterized,and the influence mechanism of matrix temperature on LIBS was disc?ssed.The details are as follows:1.The matrix temperature range of the experiment under the air environment is from 20 ? to 410 ?.The experimental results show that the LIBS signal intensity I increases with the increase of the matrix temperature,and the signal intensity at temperature 410 ? is about 6 times that of the intensity at room temperature.Therefore,in the air environment,raising the matrix temperature is beneficial to improve the sensitivity of LIBS analysis.The laser plasma temperature and electron density increase as the matrix temperature increases.When the matrix temperature is high,a crater with larger diameter than the room temperature but shallower depth is obtained.That is beneficial to the longitudinal depth analysis of LIBS.When the matrix temperature is 410 ?,the volume of the crater is larger than that at room temperature.Oxidation ca?sed by matrix temperature increase in air environment,is also an important factor that affects the morphology of the crater and further affects the laser induced breakdown spectrum of the tungsten-molybdenum alloy.2.The matrix temperature range of the experiment under the argon atmosphere is from 20 ? to 400 ?.The experimental results show that the LIBS signal intensity increases with the increase of the matrix temperature,and the signal intensity at temperature 400 ? is about 13 times that of the intensity at room temperature.Therefore,in the argon environment,raising the matrix temperature is beneficial to improve the sensitivity of LIBS analysis.The laser plasma temperature and electron density increase as the matrix temperature increases.When the matrix temperature is high,as in the air environment,a crater with larger diameter than the room temperature but shallower depth is obtained.But unlike the air environment,when the matrix temperature is high,the volume of the crater is less than that at room temperature in argon.3.The matrix temperature range of the experiment under the vacuum environment is from 20 ? to 606 ?.The experimental results show that the LIBS signal intensity changes little with the increase of the matrix temperature.The laser plasma temperature and electron density remains almost unchanged with the change of the matrix temperature.The effects of matrix temperature on the analysis of LIBS in different environments are different.These provide the necessary experimental basis for the future development of online diagnostic systems in complex environments,and have a certain role in promoting the development of high-precision and quantitative development of LIBS technology.