CNT冷阴极微焦点X射线管研制

Development of a Micro-focus X-Ray Tube Based on Carbon Nanotube Cathode

以单根微米直径的碳纳米管(CNT)纱线为场致发射的电子源,通过Opera软件的模拟仿真进行阴极结构的设计,研制了基于CNT冷阴极,仅需静电聚焦实现微焦点,以金属管壳进行超高真空封装的小型闭管式微焦点X射线管。测试表明,单根直径50μm的CNT冷阴极电子源可以实现500μA的连续稳定电流发射;此时栅极控制电压V GC为886 V,对应的电场强度为1.77 V/μm,微型阴极的发射电流密度达到25.5 A/cm^(2)。金属封装的X射线管可以稳定工作于130 kV的阳极高压,通过调节聚焦电压,基于静电聚焦结构可实现45μm×58μm的焦点尺寸。研制的微焦点X射线管以50%的占空比工作,使用线对卡测试,分辨率达到了20 LP/mm,并对芯片等元件进行成像表征,内部微米级金线图像清晰。该微焦点X射线管可满足芯片、新能源电池等精密元件的无损检测需求,具有较好的应用前景。

A miniaturized closed tube micro-focusing X-ray tube based on a CNT(carbon nanotube)cathode is developed,using a single micrometer-diameter carbon nanotube yarn as the field emission electron source.The cathode structure is designed and simulated using Opera software.The micro-focusing is achieved through electrostatic focusing,and the X-ray tube is enclosed in a metal housing for ultra-high vacuum sealing.Experimental results demonstrate that a continuous stable current of 500μA can be emitted from a single CNT yarn cathode with a diameter of 50μm.The corresponding grid control voltage(VGC)is 886 V,resulting in an electric field intensity of 1.77 V/μm.The emission current density of the micro cathode reaches 25.5 A/cm2.The metal-housed X-ray tube can operate stably at an anode high voltage of 130 kV.By adjusting the focusing voltage,a focal spot size of 45μm×58μm is achieved using the electrostatic focusing structure.The developed micro-focusing X-ray tube operates at a duty cycle of 50%and achieves a resolution of 20 LP/mm through line pair card testing.It is capable of imaging and characterizing internal micro-scale components such as gold wires in chips.This micro-focusing X-ray tube meets the non-destructive testing requirements for precision components such as chips and new energy batteries and holds great potential for various applications.