Design and Experimental Validation of an Insulated Collector for a High-Power W-Band Extended Interaction Oscillator

This paper presents the design of an insulated collector for a high-power W-band extended interaction oscillator (WEIO), integrated into the water-cooling system. Beryllium oxide (BeO) ceramic brazing is employed to electrically isolate the depressed collector from the heat sink, enabling the two components to share a single high-velocity cooling circuit with purified water as the cooling medium, thereby simplifying the overall thermal management system. Under steady-state operation with a 43.5 kV, 2.3 A sheet beam, the full-state spent-beam collection method was adopted, and electrons from one representative period after beam-wave interaction were selected for particle-tracking simulation. Based on this analysis, a slope-wall depressed collector was designed. Simulation results indicate that the overall efficiency increases from 18.22 to 48.24% when a −27 kV potential is applied to the collector. When secondary electrons are taken into account, the collector efficiency and back-streaming current are 75.83% and 1.8 mA, respectively. Subsequently, thermal analysis and coupled particle-thermal simulations were performed, confirming the effective heat-dissipation capability of the designed collector. Finally, a truncated collector prototype was fabricated and tested for high-voltage breakdown in air, where electrical breakdown occurred at 20 kV. Combined with electrostatic simulations, the results indicate that the full-scale collector can reliably operate at 27 kV in vacuum. These results demonstrate the feasibility of the proposed high-voltage insulated collector.