The High-Order Coalesced TM11-Like Mode Operation for 220 GHz Sheet Beam Traveling-Wave Tube

Sheet beam vacuum electron tubes are an attractive solution for high-power sources or amplifiers at millimeter-wave and terahertz range. In this article, a high-order coalesced TM
₁₁
-like mode operation for 220 GHz sheet beam traveling-wave tube is proposed. The feasibility of coalesced TM
₁₁
-like mode operation is investigated. The utilization of high-order mode expands the RF circuit power capacity, increases the beam current and reduces the cathode emission density. The self-consistent nonlinear code and three-dimensional particle-in-cell simulations are used to verify the 6.7% beam-wave interaction at 220 GHz without phase matching optimization. The maximum output power reaches 370 W. The results demonstrate this methodology is a good solution to build a high-power device for a wide region of terahertz.