Abstract
Abstract A micro focus x-ray tube that generates x rays with a micrometer-sized focal spot is a key device for high-resolution x-ray radiography and tomography because X rays with smaller focal spot size yield finer x-ray images with higher magnification factor. The x-ray focal spots of conventional thermionic micro-focus x ray tubes are normally less than 20 μm in size.The major purpose of my research is to design and optimize a new micro-focus X-ray tube with a spot size on the target less than 25μm. Also, the target assembly has to withstand the high power density of an electron beam without being damaged.During the exploring process in order to achieve the desired level of x-ray focal spot, I considered the following three steps.The First step: Use electronic control system on the JP-EGUN with the emitter hiddenbehind the cap hole to investigate the effect of Vbias on the focal spotsize.The Second step: Design the gate electrode inclined to the cathode inducing a focusingelectric field on the electron beam to see if the PIRECE GUN canconsiderably reduce the minimum radius of the electron beam.The Third step:Optimize several X-ray target parameters for the X-ray intensity and X-raystability.