摘要
计算机层析成像(CL)技术可以对大尺寸板状构件进行高精度无损检测,但对样品台的精度要求极高,导致设备造价昂贵,且受限于X射线亮度、扫描速度较慢,不利于推广应用。基于以上限制,提出环形靶高速扫描微焦点X射线源,通过电子束快速扫描环形靶材产生以圆形轨迹运动的微焦点X射线源,可以大幅度提高样品检测效率,但电子束在扫描过程中会产生偏转像差,形成畸变,需要在利用像差校正系统的同时约束其偏转角度,从而保持电子束的束斑尺寸和形状。从理论上分析了电子束扫描过程中,像差、工作距离与扫描范围对束斑尺寸和形状的影响,通过Munro’s Electron Beam Software(MEBS)电子光学计算软件进行建模并进行了计算分析,给出了不同工作距离下可以保证电子束束斑尺寸和形状的最大偏转范围。该研究为环形靶高速扫描微焦点X射线源中电子束控制系统和靶材的设计提供了理论参考。
Objective Computed laminography(CL)technology can conduct high-precision non-destructive testing of large-size plate components.The extremely high precision requirements of the sample stage result in expensive equipment,being limited by the brightness of X-rays,and small scanning speed,which are not conducive to the promotion of the application.Based on the above limitations,a high-speed scanning micro-focus X-ray source for ring targets is proposed,which generates a micro-focus X-ray source with circular trajectory motion through rapid scanning of a ring target by an electron beam and can substantially improve the sample inspection efficiency.But the electron beam will produce deflection aberration during scanning leading to aberrations,and it is necessary to utilize an aberration correction system while constraining the deflection angle to maintain the beam spot size and shape of the electron beam.Methods In this paper,based on the theory of electron optics,the effects of aberration,working distance,and scanning range on the beam spot size and shape during the scanning process of the electron beam are theoretically analyzed,and then the physical model of the ring target high-speed scanning micro-focus X-ray source is established based on the electron optical calculation software of Munro’s Electron Beam Software(MEBS).Then,the physical model of the ring target highspeed scanning micro-focus X-ray source is established based on MEBS,and the minimum beam spot size corresponding to the absence of the scanning field at different working distances,as well as the beam spot sizes at the farthest edge of the scanning field at different working distances,scanning ranges and aberration correction systems is calculated.Finally,based on the analysis of the calculation results,the maximum deflection range that can guarantee the spot size and shape of the electron beams at different working distances,and the effects of different aberration correction systems on the spot size and properties at the farthest edge of the deflection field are given.Results and Discussions Under the same working distance,as the scanning range increases,the degree of beam spot ellipticity becomes larger(Fig.7);under the same scanning range,as the working distance increases,the degree of beam spot ellipticity becomes smaller(Fig.8).For different scanning ranges,there exists a critical working distance,and within this scanning range,the beam spot size and shape of the electron beam do not change much.When a scanning range and a working distance are converted into a scanning angle,there exists a relatively optimal critical scanning angle of about 2.87°(0.05 rad),less than which the deflected beam spot aberration is small.After using the aberration correction system,the quality of the beam spot at different deflection ranges and working distances is significantly improved,and the corresponding scanning angle is increased to some extent(Table 3).Conclusions This paper presents theoretical analysis and simulation work on the electron optics of a micro-focus X-ray source for high-speed scanning of ring targets.The relationship among the beam spot size and shape,the working distance,and scanning range is revealed,and the relatively optimal critical scanning angle is about 2.87°(0.05 rad),in which the spot size and shape of the electron beam can be guaranteed to be basically unchanged.After the aberration correction,this scanning range is increased to some extent.This work provides a theoretical reference for the designs of the electron beam control system and target material in the ring target high-speed scanning microfocus X-ray source and confirms the feasibility and great potential of the static high-speed CL scanning system based on the ring target.In future work,the design will be further optimized by combining the existing calculation model,the existing micro-focus X-ray source prototype will be modified,and experiments will be designed for validation,which will bring its real application in nondestructive testing scenarios of plate components.
作者
史丽娜
牛耕
刘俊标
韩立
Shi Lina;Niu Geng;Liu Junbiao;Han Li(Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《光学学报》
北大核心
2025年第7期342-349,共8页
Acta Optica Sinica
基金
中国科学院电工研究所科研基金(E155440101)
中国科学院科研仪器设备关键技术团队项目实施方案(PTYQ2024BJ0002)。
作者简介
通信作者:牛耕,niug825@mail.iee.ac.cn;通信作者:刘俊标,liujb@mail.iee.ac.cn。
