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Additive manufacturing is rapidly opening its way into many areas of the aerospace industry, where different 3D printing technologies are finding niche applications in which they do not only simplify the process and allow shorter lead times, but also the particularities of these new fabrication methods yield new material properties that enhance the component and can lead to higher performance and longer service life of an aerospace system. Although rapid manufacturing processes are being tested for in-space manufacturing and are commonly used to fabricate UAV parts and some spacecraft subsystems with 3D printed components have been tested in space, little research has been conducted on the potential application of these techniques to electric thrusters. This paper presents the study conducted on the application of selective laser melting, a powder bed fusion technology, to the fabrication of ion engine grids and the challenges faced during the process. The first proof of concept and its optimization are described. Later, the development of the selective laser melting process for molybdenum, the study of the 3D printed materials' properties, their direct application to ion extraction systems, and the tests of additively-manufactured ion optics are described. It was found that 3D printed grids can be accurately fabricated with titanium and molybdenum, that they perform similar to conventional optics in short tests, that the selective laser melting process allows certain control of the coefficient of thermal expansion of the output and that this fabrication method allows the reproduction of sputtering erosion patterns. Future research in this direction will cover sputtering tests of selectively-laser-melted samples and the additive manufacturing of carbon-carbon grids.

Purpose Traditional ion optics manufacturing processes are complex and costly. The purpose of this paper is to study the feasibility of using selective laser melting (SLM) to produce additively manufactured ion optics. Design/methodology/approach An SLM machine was used to generate Ti6Al4V screen grids. The output was separated through wire cutting from the build platform and studied through a scanning electron microscope. To increase the geometrical accuracy of the original grid, samples consisting of nine-aperture arrays were fabricated with different parameter combinations, increasing the energy density. An empirical method to correlate the energy density applied in the fabrication process with the dimensional accuracy of the hole array positioning was developed through the analysis of multiple samples. Findings The SLM machine generated grids with optimal microstructure, the apertures fell within the specified tolerances and tolerances of slightly less than 10 µm can be guaranteed for the hole array positioning. The grids’ upper surfaces presented good-quality surface finish, and the lower surface quality was acceptable when the wire cutting process that separated the grid from the build platform performed slowly. Regardless of the build strategy, the stresses generated in the separation process caused the warping of the ion optic, so a flattening operation was necessary in all cases. Originality/value This research proved that SLM is a viable solution for ion optics fabrication, faster (less than 24 h) and less expensive (order of US$300) than traditional fabrication methods (with fabrication times from 24 to more than 400 h and costs from US$500 to US$5,000, depending on the material, size and shape).

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