傅里叶变换法计算焊接电弧光谱Stark展宽研究

摘要

利用电弧光谱,采用Stark展宽法计算电子密度是测量等离子体电子密度最有效、最准确的方法.而如何从众多展宽机制复合的谱线中分离出Stark展宽是应用Stark展宽法的难点.利用傅里叶变换从测得的光谱线形中分离出Lorentz线形,从而准确获得Stark展宽,并且计算了TIG焊电弧等离子体电子密度的分布.这种方法不需要准确测量电弧温度,不需要测量仪器展宽并且对数据有去噪作用.计算结果表明:在轴线上,TIG焊电弧电子密度随着离钨极距离的增大而减小,变化范围在1.21×1017～1.58×1017 cm-3之间；在径向,电子密度随离轴距离的增大而降低,在靠近钨极区域具有离轴最大的性质.%It's the most effective and accurate method to calculate the electronic density of plasma by using the Stark width of the plasma spectrum. However, it's difficult to separate Stark width from the composite spectrum linear produced by several mechanisms. In the present paper, Fourier transform was used to separate the Lorentz linear from the spectrum observed, thus to get the accurate Stark width. And we calculated the distribution of the TIG welding arc plasma. This method does not need to measure arc temperature accurately, to measure the width of the plasma spectrum broadened by instrument, and has the function to reject the noise data. The results show that, on the axis, the electron density of TIG welding arc decreases with the distance from tungsten increasing, and changes from 1. 21×1017 cm-3 to 1. 58×1017 cm-3; in the radial, the electron density decreases with the distance from axis increasing, and near the tungsten zone the biggest electronic density is off axis.