Optimization Research On Excitation And Detection Device Of Light Element XRF Analyzer

The energy dispersive X-ray fluorescence analysis(EDXRF)method is favored by modern industrial production because of its simple operation,fast analysis speed and wide analysis range.However,the energy of light element characteristic X-ray is low,ranging from 0.052 ke V to 0.4012 ke V,which is seriously affected by the matrix,and the energy of the characteristic spectral line is close and not easy to identify.Therefore,the application of EDXRF analysis technology in the light element analysis field is restricted to a great extent.After investigating the problems and comprehensive analysis of the light element fluorescence analyzer detection device,this article uses the Monte Carlo method to establish the device model to simulate the internal parameters of the X-ray tube and the device geometric parameters.Through the analysis and research on the detection device of the light element X-ray fluorescence analyzer,the structural parameters simulated by the Monte Carlo method were determined,and the MCNP5 software was used for the simulation.By studying the working principle of light element fluorescence analysis detection device,the excitation source and geometric arrangement of the device can directly affect the detection efficiency of light element.Therefore,in this paper,the monte carlo method is used to establish the model of X-ray tube and detection device with MCNP5 software,and the internal parameters of X-ray tube and the geometric parameters of light element analysis device are simulated.The main research contents and achievements of this paper are as follows:(1)through structural analysis,the influences of target type,target thickness,Be window thickness and tube voltage on the results were determined,and the optimal Xray tube parameters for light element fluorescence analysis detection device were obtained: the anode target was Ag with a thickness of 3μm,Be with a thickness of 150 μm,and the optimal excitation voltage was 10 k V.(2)Based on the traditional "Tube-Example-Detector" model,the optimal geometric parameters were determined: the included Angle between the center line of the X-ray tube emission window plane and the sample plane was 70°,and the included Angle between the center line of the detector’s detection window plane and the sample plane was 80°,at which time the Al K characteristic peak-to-peak ratio was the largest and was 4.27.At the same time,the effects of different internal environments on the detection count were simulated,and the Al K peak-back ratio in vacuum was found to be 2.05 times that of the Al K peak-back ratio in helium.(3)In polarization three-dimensional secondary optical path layout design reflective secondary target model,the optimization parameters for: reflective secondary target material chooses Ag,the centerline of X ray tube launch window and reflective secondary target Angle is 65°,reflective secondary target plane plane centerline 50° Angle to the sample,sample surface and the probe of the center line of the detection window Angle 60°,Al K alpha back ratio of the maximum peak at this time,and for 8;(4)The transmission secondary target model was designed and established,and its optimal parameters were determined as follows: the angle between the center line of the excitation source(the transmission secondary target plane)and the sample plane was 60°,and the angle between the center line of the detector window plane and the sample plane was 80°,which had the best detection effect.Through theoretical research and a lot of simulation analysis by montagaro method,the results show that the transmittance secondary target model is far superior to the reflection secondary target model,and the reflection secondary target model is also inferior to the "pipe-sample-probe" model,so the transmittance secondary target model is more suitable for the light element fluorescence analyzer.