A ridge-loaded staggered double-vane slow wave structure for terahertz radiation sources

A ridge-loaded staggered double-vane slow-wave structure is proposed for terahertz radiation sources employing a sheet electron beam. This slow-wave structure has the advantages of enhanced electric field and energy density distribution and improved interaction impedance in the beam-wave interaction region. High-frequency characteristics are investigated for the proposed slow wave structure and compared with those of the staggered double-vane slow wave structure. The slow wave structure is fabricated and experimentally tested for transmission and reflection properties, revealing \(S_{21}\) above -2 dB and \(S_{11}\) below -17 dB at 0.34 THz for a backward wave oscillator. Steady transmission of the 21.7 kV sheet electron beam is achieved by designing a periodic cusped magnetic system (0.2 T) along with a sheet electron beam gun (50 mA). Beam-wave interaction simulations utilizing 100 periods demonstrate a peak power of 14 W and continuous frequency tuning from 0.295-0.375 THz for the proposed slow wave structure, whereas the staggered double-vane slow wave structure achieves 8.5 W peak power and frequency tuning from 0.308-0.366 THz. The sensitivity of the output power to the added ridge geometry is also analyzed. These findings indicate that the novel ridge-loaded staggered double vane slow-wave structure is promising for developing high-power broad frequency tunable terahertz radiation sources.