High Temperature Electron Beam Additive Manufacturing of Tungsten Plasma Facing Components with Integrated Porous Armor

Controlled thermonuclear fusion promises to radically transform our society, providing nearly limitless renewal energy. Cost-competitive fusion requires plasma facing components (PFC) which can sustain extreme photon and energetic particle fluxes over a lifetime of years, as these components will dictate the maintenance and overhaul periods of future reactors. Robust, scalable PFCs manufacturing methods are critical to the future viability of fusion energy, as each reactor may have upwards of 500,000 individual PFCs, with each PFC including a solid tungsten thimble bonded to a porous tungsten lattice. Additive Manufacturing (AM) is rapidly changing the way heat transfer devices such as PFCs are designed and manufactured, reducing complex assemblies to monolithic structures. Furthermore, AM facilitates rapid prototyping, a key enabler for model benchmarking and design optimization. We propose to additively manufacture a solid, near-net shape, pure W thimble with a metallurgically bonded porous W armor using Electron Beam Powder Bed Fusion (EB-PBF). New generation EB-PBF systems include a 5,000 MW/m2 peak power density, 6kW beam and build temperatures as high as 1300oC operating in a high vacuum environment. This combination of properties makes EB-PBF well suited to printing clean, crack-free tungsten above the ductile-to-brittle-transition temperature. In this project, we propose to additively manufacture a solid, near-net shape, pure W thimble with a metallurgically bonded porous W armor using Electron Beam Powder Bed Fusion (EB-PBF). The mechanical and microstructural properties will be examined as well as the finishing, machining and vacuum brazing characteristics. We will also perform preliminary studies on cracking of densified hydrogen-reduced tungsten powder, as well as create a mechanical design for testing our W parts under high heat flux conditions. In Phase II, we will produce complete tungsten plasma facing components with integrated lattice armor with the objective of reducing the recrystallization and thermal stress limitations associated with current PFC designs. Furthermore, these parts will be tested under cyclic, high heat flux conditions, a first for additively manufacturing tungsten. Batch production of PFCs using additive manufacturing could simplify fabrication while also enabling more complex PFC architectures. Identifying powder characteristics and build parameters for full density tungsten components could significantly transform the design and lifecycle of future fusion reactors. Similarly, printing tungsten heat exchange components with integrated cooling could have significant applications in other fields such as medical imaging, radiation oncology and hypersonic vehicles.