Increasing the energy of the electron beam striking an X-ray target can lead to higher electron to X-ray conversion efficiency. For a given electron beam energy, the conversion efficiency can be enhanced through various methods. Optimizing the electron beam parameters, such as beam current, pulse width, and repetition rate, can also improve the conversion efficiency. Choice of the X-ray target material directly affects the X-ray production efficiency, as different materials have different X-ray emission and absorption properties. Selecting a high atomic number (Z) target material (tungsten, gold, tantalum) is a straightforward way to improve the X-ray production. Finally, optimizing the target geometry and thus, the electron-beam and target interaction, can also improve the efficiency of electron to X-ray conversion. The target design should enable the maximum possible interaction of the electron beam with the target material. This can be achieved by optimizing the thickness and shape of the target material, and the placement of the target relative to the beam path. X-ray beam optics can also be employed to focus the X-rays and reduce their loss, thereby increase the net X-ray flux reaching at the object of interest. AwareAbility Technologies (AAT), in collaboration with The Ohio State University (OSU), proposes to develop a novel transmission-type X-ray target with high X-ray production efficiency, which is capable of X-ray performance beyond the traditional high Z Bremsstrahlung converters. The proposed X-ray transmission target will utilize an array of microstructure features on a substrate. These features will have a wall made of a high Z material. The microstructures will be created in a linear 2D pattern on the surface of the substrate which will be made of a low Z material. This composite target design helps to minimize X-ray self-absorption in the target material and improve the net electron-to-X-ray conversion efficiency. The novel target structure will serve to increase the total effective surface area available for interaction of the incident electron beam with the target. The purpose of the target substrate is manifold - to provide a surface to create the microstructures, to act as base material supporting the microstructure, and to serve as a potential X-ray exit window. The net effect of this structured target design is expected to be an enhanced electron-to-X-ray conversion efficiency and higher X-ray flux than that achievable with a traditional thick reflection target or a transmission target with a smooth planar surface. Another advantage of the proposed design would be a reduction in the overall energy/heat deposition in the target for a given incident electron beam power when compared to a conventional thick target.
