Constructing a field-emission (FE) x-ray tube

该项目旨在构建一台配备多场阴极（MFC）作为电子源的X射线相机。1999年3月1日前完成了X射线照相机的研制和试验。X射线照相机的总体系统基本上由照相室、电子源和抽气系统组成。各部件概述如下。1）X射线照相机X射线照相机完全由一个不锈钢圆柱形腔室组成，带有七个观察和连接端口。2）电子源FE发射体或电子源可以在不破坏主真空的情况下进行更换。它的位置调整是在操纵器的帮助下完成的，从它发射的电子通过格雷泽透镜聚焦到目标上。3）泵浦系统照相机室<-7>在两个分子泵的帮助下被抽到-10 Torr。所用场阴极为简单切割的钼网。需要强调的是，使用这种简单的网格发射器获得了清晰的X射线图像。这确实是“划时代的”，因为迄今为止还没有使用场电子记录x射线图像。一个不期望的结果是，<-7>由于O形环将腔室和高压绝缘体联合收割机结合，腔室压力保持在10 μ Torr的量级。由于场致发射是一种典型的表面现象，因此需要超高真空（UHV）来维持电子源的稳定工作。因此，我们的下一步是根据我们在本项目中获得的各种经验构建一台UHV X射线相机。

This project aimed at constructing an x-ray camera equipped with a multiple field cathode (MFC) as the electron source. The construction of the x-ray camera and its test were completed before March 1, 1999.The total system of our x-ray camera is basically composed of camera chamber, electron source and pumping system. The respective components are outlined as follows.1) x-ray cameraThe x-ray camera is entirely composed of a stainless-steel cylindrical chamber with seven viewing and connection ports. Inside the chamber are installed an Al target and a Grazer lense, the latter of which is water-cooled.2) Electron sourceThe FE emitter, or the electron source, is exchangeable without breaking the main vacuum. Its position adjustment is done with the aid of a manipulator, and electrons emitted from it are focused onto the target through the Glazer lense.3) Pumping systemThe camera chamber is pumping down to -10^<-7> Torr, with the aid of two turbomolecular pumps. The field cathode employed were Mo meshes simply cut by a scissor. It is emphasized that sharp x-ray images were obtained using such a simple mesh emitter. This is really "epoch-making" because no x-ray image has been recorded so far by using field electrons. One undesirable result is that the chamber pressure remained at the order of 10^<-7> Torr because of an 0-ring to combine the chamber and the high-voltage insulator. Since field emission is a typical surface phenomenon, a ultrahigh vacuum (UHV) is demanded to maintain a stable operation of the electron source. Our next step is thus to construct a UHV x-ray camera based on a variety of experiences that we had in the present project.