Broad-Wall Loaded Photonic Crystal Waveguide Slow Wave Structure for the Terahertz Traveling Wave Tube

A broad-wall loaded photonic crystal waveguide (BWPCW) slow wave structure (SWS) for the terahertz traveling wave tube (TWT) has been presented in this article. The frequency-selective properties of photonic crystals are studied. The mode competition can be adequately suppressed by introducing photonic crystals into the SWSs. The parameters of the SWS and couplers are optimized to achieve a high-performance TWT at 220 GHz. The results of simulation of high-frequency characteristics show that the BWPCW-SWS has an interaction impedance of 1.02-3.62 Omega and an ohmic loss of 0.050-0.076 dB per period in the passband. The beam-wave interaction results indicate that the proposed BWPCW-TWT can produce a saturated output power of over 80 W ranging from 198 to 261 GHz when the operating voltage is 24.5 kV and the beam current is 150 mA. At 220 GHz, the maximum electron efficiency and saturated output power attain 4.35% and 160 W, respectively, with an input power of 0.55 W.