Development and Modeling of W-band Sheet-Beam Tubes with Grating Slow-Wave Structures

The results of design, simulation and development of W-band traveling-wave tube (TWT) and backward-wave oscillator (BWO) with sheet electron beam and grating slow-wave structure (SWS) are presented. Design of the SWS was optimized to obtain synchronism voltage of 10–12 kV. The results of 3D particle-in-cell (PIC) simulation of beam-wave interaction are presented. The TWT with staggered double-grating SWS provides nearly 30 dB small-signal gain, 15-GHz bandwidth, and up to 50 W power at saturation. The BWO with single grating SWS provides up to 20 W output power. Electron gun providing 0.1-A sheet electron beam is designed and fabricated. Grating SWS is fabricated by a novel technology based on diffusion bonding of alternating copper and molybdenum plates and subsequent chemical etching of copper. Other key components of the device, such as depressed collector, permanent-magnet magnetic focusing system, and vacuum window are designed and currently are under fabrication.