Additive Manufacturing of Large, Complex 3D, Metal and Alloy Structures for High-Vacuum Applications

Fusion science has immediate need for fabrication of high-vacuum complex 3D structures. We propose to develop the know-how necessary to use metal additive manufacturing (AM) to produce structures (such as chambers) possessing vacuum and structural characteristics that meet this need. Traditional methods for producing high-vacuum components typically require the manufacturing of multiple parts, subsequently joined by welding, vacuum seals, and/or fasteners. This process can be time consuming and result in assemblies that fail to meet dimensional and vacuum specifications. Additive manufacturing can improve the fabrication and performance of the components. It (a) enables production of a 3D geometry as a single component from a 3D CAD model, (b) enables structures that cannot be built with traditional methods, and (c) offers the potential to more rapidly and cost effectively realize a complex structure. The ability to quickly and economically produce and evaluate hardware is key to accelerating the realization of fusion energy. AM is an attractive solution, yet there is little data on high-vacuum properties of components. This deficit inhibits use of direct energy deposition (DED) processes, which are well suited for rapid builds of large products. Resolving this fundamental technology gap is a key motivating factor. Our research will leverage the capabilities of electron beam metal DED. Its advantages include deposition rate and economy of the wire-fed process and availability of a broad range of metal-alloy feedstock. This will increase likelihood of successfully realizing rapid and cost-effective large-scale 3D builds having a refractory-metal as one of the layers; characteristics of broad value for fusion energy applications. Key goals of this AM research and development (R&D) are to identify build solutions suitable for high- vacuum compatible metal structures. We will: (a) use two (or more) alloys in a build, (b) establish layering of an alloy and a refractory metal, (c) explore creation of material gradients, and (d) investigate feasibility of printing channels. Methods used to characterize properties of the resultant builds will include vacuum measurements, mechanical measurements, 3D scanning, and radiography. This work has the potential to reduce manufacturing complexity, expedite concept-to- implementation, and optimize hardware implementations. This R&D will demonstrate the capability to realize rapid and economical production of high-vacuum components for fusion applications. We will retire current technical risks and ultimately enable provision of this AM capability as a commercial service.