Super-miniature x-ray tube

Abstract

A transmission x-ray tube super-miniature in size is described. The x-ray tube is $5\mathrm{mm}$ in diameter, and comprised of a built-in electron-emitter assembly and a grounded planar target. The key component of the emitter assembly is a Kovar pipe $2\mathrm{mm}$ in diameter, inside which carbon nanofibers aligned on an electro-polished molybdenum tip are loaded to serve as the electron emitter. This type of electron emitter is highly robust in non-ultrahigh vacuum, continuing to field emit electrons for $100\mathrm{h}$ or longer at pressures in the ${10}^{-5}\mathrm{Pa}$ region. This x-ray tube provides clear x-ray images.