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An analysis of slow-wave structure (SWS) for vacuum-electron traveling wave tube is carried out using COMSOL Multiphysics software. A helix SWS is used as an example to model and perform fully coupled 3D electromagnetics cold-simulations and beam-wave interaction hot-simulations. The preliminary COMSOL simulation results show good agreement with calculations from CST studio software.
A possibility of a significant increase in the electronic efficiency of TWTs is considered in this paper. The output power and the power at the attenuator of a two-section TWT are measured, simulated, and calculated analytically at a fixed frequency for different distances between the attenuator and the output terminal. The significant difference between the output power and power at the attenuator's...
This paper focus on an issue that vacuum electronics engineers face while designing wide band slow-wave structures for traveling wave tubes: The obtaining of reasonably flat gain curve over the bandwidth. It is usual to try a tradeoff between synchronism and interaction impedance profile in order to achieve a better gain response. We show here results from an in house one-dimensional large signal...
In this paper, helix slow-wave structures with one sever, two severs and three severs are proposed for kilowatt millimeter wave helix TWT. According to the small-signal theory of BWO, we can calculate the oscillation length of BWO. By setting different sever in TWTs, we successfully make the length of the un-attenuated part shorter than the threshold of BWO and finally achieve the suppression of BWO...
We have studied the electromagnetic properties of bi-helix slow-wave structures (SWSs) with added azimuthal conductors in the form of: 1) metal rings connecting the helices and 2) an azimuthally conducting screen formed by metal rings with and without capacitive gaps. We show that these added azimuthal conductors suppress backward-wave oscillation and enable stable high-voltage, high-power operation...
High power wideband helical antennas are currently being designed, simulated, and constructed at the University of Missouri-Columbia's Center for Physical and Power Electronics laboratory. The program CST Microwave Studio was used to simulate antenna designs derived from Krauss's formulas. Once simulations proved to be functional, the antennas were constructed, characterized, and compared against...
Novel rod shapes, to improve dispersion and interaction impedance of helix slow-wave structures for wide band traveling wave tube, are proposed. Cold parameters are validated by 3-D electromagnetic code demonstrating the accuracy of the adopted analytical method.
In this work, we attempted to obtain a collection of useful results to guide the design of broadband helical slow-wave structures. A 3D eigensolver was used to model vane loaded slow-wave structures. Plots of phase velocity and interaction impedance as function of a normalized frequency were taken varying some geometric parameters. The result is a collection of plots showing how the vane geometry...
The helical slow-wave circuit is an attractive choice for traveling wave tube amplifiers (TWTAs) because of its inherently large bandwidth and relatively high RF efficiency. Unfortunately, as the operational frequency increases beyond Q-or V-band, its use has been limited by conventional fabrication techniques, and by the difficulty of passing enough current through the center of such a small structure...
Equivalent parameters of the helical SWS in the anisotropically conducting cylinders and their dependence on the operational frequency had been considered in this paper. The possibility of the independent control of the interaction impedance and dispersion characteristic is the main issue of the provided analysis. Solutions of the wave equations in the anisotropically conducting sheet approximation...
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