Design of X-ray targets for high-brightness microfocus X-ray tube

Abstract

A detailed study of the designing of an X-ray target is enclosed with an emphasis on maximizing the brightness of X-rays produced. The research is aimed at the minimization of the focal spot size by virtue of the geometric parameters of the transmission-type targets. Two different configurations of the transmission-type target have been considered. X-ray emissions from these targets were studied in detail using Monte-Carlo simulation code MCNP5. In the first part, parameters of a laminated configuration of transmission-type target have been optimized for a microfocus X-ray tube to produce high brightness of X-rays for a broad range of electron energies from 30 keV to 150 keV. In the second part, a novel concept is put forth to develop a microfocus X-ray tube based on a microstructured X-ray target that is irradiated with a nonfocused electron beam. The calculations revealed that the microstructured targets are quite capable of minimizing the effective X-ray spot sizes compared with those having a laminated configuration. Based on the simulation results of X-ray brightness, optimum geometric parameters were derived for the microstructured targets with different morphologies. The combination of the micro-structured targets and nonfocused electron beam allows the miniaturization of a microfocus X-ray tube by eliminating the needs for massive and complex focusing devices. Moreover, limitations of the maximum allowable electron beam currents for the stable operation of the X-ray targets are presented.