Invited Paper VT-TuM10
Vacuum Electronics Community Pioneers Additive Manufacturing of Copper

Tuesday, October 22, 2019, 11:00 am, Room A213

Even though there are many players in the world of additive manufacturing (AM), vacuum electronic devices (VED) community made a significant impact on AM of copper specifically, with recognition by industrial partners and government agencies. Copper is a challenging material to print because of its high reflectivity and high thermal conductivity; material purity is also hard to achieve due to the lack of high quality precursors. VED community has the most stringent requirements for copper. The successful implementation of copper AM for VEDs will support a wide range of applications, including thermal management, power electronics, and nuclear. Many critical to VED manufacture properties have been achieved (density, ultra-high vacuum compatibility, electrical and thermal properties), but few still remain to be challenging (reduction of oxygen content and surface roughness). A variety of components relevant to VED community have been manufactured; more interesting examples include: high efficiency klystron output cavity with micro cooling channels and weight reducing web support structure; one inch long sections of WR-10 waveguide demonstrating post-polishing techniques to reduce surface roughness to 2 microns in enclosed envelopes, coupled cavity travelling wave tube amplifier circuit structures demonstrating over 50% cost reduction capability. Most of the benefits that AM can offer still lie ahead to be explored: predesigning material properties local to specific design features while varying physical, electronic, or chemical properties locally.