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This paper describes the first stages in the development of an interaction circuit for a 12 kW X-band pulsed traveling wave tube. Requirements suggest a coupled-cavity slow wave structure is the best choice due to power handling, ease of manufacturing, and sufficient bandwidth. We present here the main features of the circuit and the cold model results as well. We are using mainly the HFSS 3D software...
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...
We derive analytic formulae for the electrostatic force between ring and disc charge distributions inside a grounded metallic pipe using the Green’s function technique. These distribution models are useful in the modeling of electron beams commonly employed in microwave tubes. We analyze the electric force between two discs, between two rings, and between a disc and a ring and we compare the results...
This paper presents some experimental results of unloaded Q-factor, Q0, measurements in klystron cavities using the critical points method. The circuit model and impedance locus involving this method are outlined in order to present the experimental procedure. The values calculated for a typical reentrant S-band klystrons cavity, using a vector network analyzer, were 3394 for the unloaded Q0, 1.2715...
This paper presents the experimental results of Rsh/Q0 measurements in klystron cavities using the perturbation technique. The theory involving this technique results in an expression which depends on the natural frequency f0 and the perturbed frequency shift Δf, both measured using a cylindrical reentrant cavity with offset gap built in the laboratory. In addition, it is used a cylindrical cavity...
In this work, we present a comparison between plasma reduction factors for the case of a pencil e-beam inside a hollow metallic pipe. The values under comparison were obtained via analytic expressions given in the literature and the result of a 1D large signal time domain code. The main distinctive feature of this analysis is the additional consideration of dc space charge forces, since the actual...
In this work, we relate some recent advances in the simulation of non-linear behavior of TWTs by means of a home made lagrangian large signal code. Instead of using the well known charged particle model based on infinite planes weighted by space charge reduction factor, we compute the interaction among particles using the n-body interaction force calculated via the Green's function method. The e-beam...
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