Design and Experimental Study of 250-W ${W}$ -band Pulsed TWT With 8-GHz Bandwidth

To increase output power of W-band pulsed millimeter-wave traveling-wave tubes, a prototype tube with phase velocity step-tapering circuits was designed and fabricated. The simulation methodology involved the optimization of the phase velocity step-tapering, cold characteristics, and particle-in-cell (PIC) simulation. The testing data show that it was capable of delivering an output power of over 250 W in a frequency range of 89.6-97.6 GHz (8 GHz), with a maximum power of ~424 W and electronic efficiency of ~10% at 92.9 GHz, with 189-mA beam current and 22.5-kV beam voltage. Besides, more than 4-GHz bandwidth with output power of over 300 W and electronic efficiency of over 7% was obtained with saturated gain over 36 dB. It was also found that the tested output power from the prototype tube was in an excellent agreement with the PIC simulated result.