Traveling-Wave Tubes(TWTs) feature high output power and gain, and are the core component for radars and electronic countermeasure systems. This paper presents a design for a low voltage, high efficiency W-band pulsed TWT, using a novel type of Folded Waveguides(FWGs) with modified circular bends. The designed TWT, operated at 16 kV and 125 mA , is capable of delivering an output power over 125 W, with electron efficiency and total efficiency over 6.3% and 25.7% respectively, in a frequency range of 91-97 GHz.