Design and Large-Signal Modeling of a $W$ -Band Dielectric TWT

The performance capabilities of a dielectric traveling-wave tube (TWT), designed for operation near 94 GHz near the 100-W power level, are investigated using large-signal simulations. Key design elements include a dielectric liner with a moderately high dielectric constant of 13.5, consistent with magnesium orthotitanate ceramic, and the use of a solid round electron beam with properties (26-kV, 100-mA, and 0.185-mm beam radius) that are comparable to those employed in W -band coupled-cavity TWTs. The optimal simulated performance, computed assuming a 5-cm beam-wave interaction length, is 115 W of output power at 94 GHz, with 6-GHz half-power bandwidth, 10.3-dB large-signal gain, and 4.4% electronic efficiency. Technical issues, including the existence of a higher linearity Crestatron regime, the mitigation of beam charging, and thermal management, are discussed.