基于最小二乘的MEVVA源产生的金属镍等离子发射谱线的单峰拟合

在MEVVA源产生金属等离子体的发射光谱诊断的过程中,需要用＂Plasus Specline＂光谱分析软件对光谱仪采集到的等离子体发射光谱数据进行标定.但是受光谱仪分辨率的限制,某些谱线虽然有较高的谱线强度,但是标定结果与实际情况不符或者是由于不存在明确的峰值波长而不能准确标定.为解决这个问题,本文根据最小二乘法的函数逼近原理,结合原子发射光谱的多普勒展宽和洛伦兹展宽机制,在只考虑一种展宽机制的前提下,分别用高斯线型和洛伦兹线型两种轮廓函数对以上2种谱线进行函数逼近,即对光谱仪采集到的发射光谱数据点进行单峰拟合.用逼近函数的中心波长作为该谱线的波长并用分析软件对其进行标定,从而实现用＂Plasus Specline＂软件对光谱仪采集光谱信号中每一条谱线的准确标定.在函数逼近的过程中,分别采用改进后的牛顿迭代法、变量轮换法和模式搜索法3种优化方法求解逼近函数,并对这3种方法的优化效果进行比较.

SINGLE PEAK FITTING BASED ON LEAST SQUARES DURING EMISSION SPECTRAL DIAGNOSIS OF NICKEL PLASMA PRODUCED BY MEVVA ION SOURCE

Emission spectral diagnosis of MEVVA nickel plasma requires demarcation of the spectrometer collected data using the "Plasus Specline" spectrum software.Although some lines showed high intensity,but due to limited spectrometer resolution,the calibration results were not consistent with the actual situation;or rather there was no clear peak wavelength therefore calibration could not be done accurately.To solve this problem,the principle of least-squares method of function approximation was used,in combination with atomic emission spectroscopy Doppler broadening and Lorentz broadening,in the hope of considering only one mechanism for broadening,using Gaussian and Lorentz line profile function respectively to do function approximation.Let the center wavelength of approximation function be the wavelength of this line,and demarcate it using analysis software.As a result,using the "Plasus Specline" software,he accurate calibration of each spectral line collected by spectrometer was realized.In the process of function approximation,improved Newton iteration method,the variable rotation method and the pattern search method were used respectively for solving approximation function,and the effects of these three methods were compared.