目的 检验熔石英光学元件表面离子束抛光过程中去除函数的稳定性。方法 对离子束进行法拉第扫描来获取束流密度信息，构建离子束抛光去除函数模型。分析离子束流密度信息与去除函数模型，并通过实验研究束流密度信息与去除函数之间的关系，获得基于法拉第扫描结果计算去除函数的方法。利用该方法求取离子束抛光过程中的去除函数特征量，分析去除函数特征量随时间的波动情况以此来判断去除函数的稳定性，并对熔石英元件表面进行离子束抛光实验。结果 在1 keV离子束能量下对离子源进行长时间的运行实验，利用上述方法计算实验过程中的去除函数。通过计算得到离子束抛光过程中去除函数的峰值去除率(Pmax)、体积去除率(V)和半高全宽(FWHM)在8 h内的变化率都小于3%。利用离子束抛光实验对Φ100 mm的熔石英光学元件进行抛光，抛光后面形PV值由0.78λ下降到0.16λ，RMS值由72.39 nm下降到16.64 nm。结论 通过法拉第扫描实现了对去除函数长时间的监测，去除函数特征量在长时间测试实验中有着很好的稳定性，并对熔石英元件表面进行离子束加工，加工后元件表面参数满足光学超精密加工的要求。

The work aims to test the stability of the removal function during ion beam polishing on the surface of fused silica components. By controlling the ion beam to scan along the Faraday cup, the ion beam density information was detected. Based on the sputtering theory, a mathematical model of the removal function was established. Experimental research was carried out on the ion beam density and the removal function information, and the relationship between them was obtained by comparing and analyzing the experimental results, and a method for calculating the removal function information was obtained based on the Faraday scan results. Using this method, the characteristic quantity of removal function in ion beam etching process was obtained, the fluctuation of the characteristic quantity of the removal function over time was analyzed to judge the stability of the removal function, and the ion beam polishing experiment was carried out on the surface of the fused silica element. The ion source was operated for a long time under the energy of 1 keV ion beam, and the removal function during the experiment was calculated by the above method. Through calculation, the peak removal rate (Pmax), volume removal rate (V) and full width at half maximum (FWHM) of the removal function during the ion beam polishing process were all less than 3% in 8 hours. Combining the ion beam polishing experiment, the Φ100 mm fused silica optical element was polished, the PV value of the polished back shape dropped from 0.78λ to 0.16λ, and the RMS value dropped from 72.39 nm to 16.64 nm. The removal function is monitored for a long time by Faraday scanning, and the characteristic parameters of the removal function have good stability in the long time experiment. The surface parameters of fused quartz element are processed by ion beam, and the parameters meet the requirements of optical ultra-precision machining.