Simulation study on the performance of micro X-ray tube with diamond optical window

Abstract

BackgroundAs a hot material, diamond has been widely used in various civil and military equipment with high hardness (Mohs hardness is 10), compressive strength (greater than 1.2 GPa), excellent thermal (thermal conductivity at room temperature is 20~22 W·cm-1·K-1, thermal expansion coefficient at room temperature is only (1.1~1.3)×10-6 K-1), optical (higher transparency to X-rays) and electrical properties. Traditional optical window material beryllium is harmful to the human body and industrial hazards, its hardness, thermal conductivity and the thermal expansion coefficient are much lower than that of diamond.PurposeThis study aims to explore the performance of micro X-ray tube with diamond optical window by simulation, obtain the best thickness of diamond for X-ray tube optical window and its shielding effect against low, medium and high energy X-ray.MethodsThe Monte Carlo method was used to calculate the effective transmission ratio, peak back ratio and transmission ratio of characteristic X rays with diamond optical window in high energy region. The X-ray tube with 50 kV tube voltage and 1.0 mA tube current was taken as an example to determine the optimal thickness of diamond.ResultsSimulation results show that the Kα characteristic X-ray effective transmittance and peak to total X-ray ratio of the silver target increase continuously with the increase of the diamond window thickness, and the optimum diamond thickness is 2.0 mm. Under the optimal thickness of 2.0 mm, the effective transmittance is 154.5%, high-energy X-ray transmittance is 74.5%, and the characteristic X-ray peak back ratio is 27.9%.ConclusionsDiamond can be used as a substitute for beryllium optical windows and has good application prospect.

Keywords

• x-ray tube
• monte carlo method
• diamond
• optical windows