Staggered-Vane Traveling-Wave Tube (SVTWT) Amplifier for High-Power V-Band Applications: Design, Fabrication, and Test

Abstract

As a part of the plan to deploy a wideband high-power module (HPM) to very high-throughput satellite (VHTS) network systems, Communications and Power Industries LLC (CPI) has been developing a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{V}$</tex-math> </inline-formula> -band high-power traveling-wave tube (TWT) amplifier. The power amplifier is designed with a staggered-vane TWT (SVTWT) circuit and a circular beam, operating at beam voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{E}_{\textit{k}}\text{)} =$</tex-math> </inline-formula> 18–20 kV and beam current ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{I}_{\textit{k}}\text{)} =$</tex-math> </inline-formula> 400–500 mA with the perveance of 0.168 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula> P. Within the development program, three prototypes have been built and tested so far—the first two prototypes only include simple features in their circuit configuration, excluding servers and complex tuning elements. The signal amplification process in the novel beam–wave scheme was demonstrated with the first prototype, showing 35 dBm of output power ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{P}_{\text{out}}\text{)}$</tex-math> </inline-formula> with 10–15 dB of small-signal gain and 4 GHz of 1-dB bandwidth (47.2–51.2 GHz). <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{P}_{\text{out}} =$</tex-math> </inline-formula> 57 dBm (500 W) and 24 dB of small-signal gain (SSG) were demonstrated over 4.2 GHz (47.2–51.4 GHz) of 1-dB bandwidth with the second prototype. During the RF test, the tube operated at the continuous wave (CW) mode (100% of duty cycle) with extra external cooling fans. The third prototype is designed with more complex features, including servers, mode anode, and multistage depressed collector (MDC). Its test results showed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{P}_{\text{out}} =$</tex-math> </inline-formula> 54 dBm (250 W) and 24 dB of SSG over 5.2 GHz (47.2–52.4 GHz) of 1-dB bandwidth, running at CW mode with extra external cooling fans.