Millimeter-wave and sub-millimeter-wave vacuum electronics amplifier development at the US Naval Research Laboratory

We present an overview of the theoretical and experimental research activities at the U.S. Naval Research Laboratory in the area of millimeter-wave and sub-millimeter-wave vacuum electronics. Amplifier and related circuit development ranging in frequency from 30 GHz to 1.35 THz at power levels from multi-kilowatts to watts will be described along with electron gun topologies that include single-, multiple-, and sheet electron beams. We also describe new ultra-violet photolithographic techniques that enable the fabrication of thick (up to 1000 μm), high vertical aspect ratio, solid copper structures with integrated beam tunnels with length-to-diameter aspects ratios of <500.