High Pressure Electron Gun for Electron Beam Welding and Additive Manufacturing

Electron beam (“ebeam”) welding and 3-D metal printing are advanced manufacturing processes critical to the aerospace, energy, and security industries because of their ability to process advanced metals with high precision. They are also important for the Department of Energy’s initiatives to develop small modular and integrally safe reactors. However traditional ebeam systems are large, slow, and expensive. These limitations arise from the need for conventional electron sources and target parts to operate inside high vacuum chambers; the larger the part, the larger the chamber. An electron source not requiring a high vacuum would enable smaller, faster, and more affordable electron beam systems. The purpose of this Project is threefold: 1) Design, build, and test a novel electron source to operate under vacuum requirements much less stringent (a “soft vacuum”) than those of traditional ebeam systems; 2) Design, build, and test a snorkel-like, soft vacuum chamber to transport electrons emitted by the novel source and which is attached to the target with a soft, moveable vacuum seal; 3) Combine the novel electron source and snorkel into an prototype integrated ebeam welding system and demonstrate welding. In Phase I, the novel electron source was designed, fabricated, and successfully operated at full power, including extraction of electrons. The snorkel was also designed. However government-mandated “shelter in place” orders delayed the final tests of the ebeam’s interaction with a metal target. These tests will be completed when the government orders are lifted. In Phase II, a next generation of the electron beam source will be designed and fabricated, using lessons learned from Phase I. This new electron source will be installed in the snorkel, which will be fabricated in Phase II. The combined system will then weld a model high- temperature alloy, with the resulting weld evaluated and certified using international welding standards. U.S. Electron is developing an electron beam system that mitigates the limitations of current electron beam processing by eliminating the requirement for high vacuum conditions and large enclosures. This will lead to a reduction in cost and complexity for ebeam processing. Simpler, easier to maintain, lower cost vacuum “roughing” pumps will replace high cost, complex, high-vacuum pumps. Drastically reducing pump- down times will increase the throughput of these systems, enabling lower cost, higher volume applications. Finally, reducing the high vacuum requirement reduces the size of ebeam systems, enabling flexible, field deployable ebeam welding applications, such as the performing long and/or deep welds on rockets and naval vessels, the on-site welding of large nuclear reactor vessels, and in-the-field repair of crucial aerospace components.