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In this article, we propose a simulation method to investigate the noise mechanism of traveling-wave tube (TWT). Based on the nonlinear theory of Lagrangian description, 1-D noise model is established to analyze the shot noise and the velocity noise of the electron beam in the drift space, which clearly shows that the beam noise propagates along the electron beam with standing wave shape. The shot noise and the velocity noise can be periodically converted into each other along electron beam transmission, which is consistent with the prediction of the classical noise theory developed by Pierce and Danielson (1954). Using the nonlinear beam–wave interaction theory, the evolution process of the shot noise and the velocity noise of the electron beam transforming to the electromagnetic wave in TWT is illustrated. The calculated results show that the input position of the slow wave circuit may affect the noise power spectral density (NPSD) of the device. The proposed method can provide more intuitive and simple images to explain the noise mechanism of TWT. [ABSTRACT FROM AUTHOR]

This paper puts forward a novel dual-beam overmoded folded waveguide (FW) slow-wave structure (SWS), which is loaded with photonic crystals. In this novel structure, the two electron beams pass through the small gaps between the photonic crystal structures and the FW; the dimension of the FW is twice larger than that of the fundamental mode structure. The novel dual-beam photonic crystal overmoded FW traveling-wave tube (TWT) is proposed on the basis of the SWS. And, a mode converter is introduced to achieve the connection between the SWS and the input/output structure, and the mode transformation. At the operating voltage of 21.2 kV and the operating current of 320 mA, the proposed TWT can generate 128 W of output power at 220 GHz, and its 3-dB bandwidth is 7 GHz, ranging from 216 to 223 GHz. [ABSTRACT FROM AUTHOR]

A high-harmonic traveling-wave tube (HHTWT) is designed, developed, and tested in this paper. This device is configured as a multiplier–amplifier with Q-band input signals and its third harmonic, i.e., D-band output power. The tested result demonstrates that 280 mW at 133.5 GHz is obtained as a result of 200 mW at 44.5-GHz input signal. The simulation and experiment validate that the high-harmonic radiation can be generated and amplified in the HHTWT. The approach described in this paper could find application in exploring high power, wideband tunable terahertz source. This paper is expanded from a conference paper on IVEC 2017. The detail design produce and tested result are added in this paper. The explanation of the simulation and tested results is also presented. [ABSTRACT FROM AUTHOR]

In this paper, a high-power Ka-band traveling-wave tube (TWT) driven by a sheet electron beam is proposed and demonstrated by means of the simulation and experimental methods. The single grating rectangular waveguide with large width-to-height ratio is used as the slow-wave structure (SWS). An $E$ -plane bend energy coupler is put forward to feed this wide SWS. An irregular transition structure between the input waveguide and the SWS is suggested and designed, which is beneficial to suppress the self-excited oscillation. For a practical electron beam (20 mm $\times \,\, 1$ mm, 150.1 kV, 850 A, and 20-ns), the output power of this single rectangular grating sheet beam TWT is larger than 750 kW from 34.5 to 35.4 GHz. The maximum power is 1.21 MW at 35 GHz, corresponding to a gain of 20.4 dB. [ABSTRACT FROM PUBLISHER]

In this paper, a wideband 220-GHz sheet-beam traveling-wave tube (TWT) based on staggered double vane slow-wave structure (SWS) is investigated. A novel method of loading the attenuator into the SWS for suppressing backward wave oscillation is proposed. In addition, a novel focusing electrode of the sheet beam gun is carried out in this paper, which is a whole structure but divided into two parts artificially, one is used to compress the electron beam in $X$ -direction and the other is used to compress the electron beam in $Y$ -direction. In addition, a novel anode is redesigned to reduce the defocusing effect caused by the equipotential surfaces. A nonuniform periodically cusped magnet is used for focusing the sheet electron beam, which is predicted to exhibit 100% beam transmission efficiency in a 75-mm length drift tube. The high-frequency characteristics of the SWS and the beam-wave interaction are also studied. The results reveal that the designed TWT is expected to generate over 78.125-W average power at 214 GHz, and the 3-dB bandwidth is 31.5 GHz, ranging from 203 to 234.5 GHz. [ABSTRACT FROM PUBLISHER]

A novel slow wave structure (SWS) named angular log-periodic meander-line is proposed for a radial traveling wave tube (TWT). In this paper, a 30 log-periods microstrip angular log-periodic meander-line SWS is studied. The dispersion of this kind of SWS is weak, which shows that it can work in a wide operating bandwidth. The more important advantage is that the operating voltage is much lower than that of the conventional TWT at the same operating frequency and the geometrical dimension is also much smaller than that of the conventional TWT. The beam–wave interaction of the angular log-periodic meander-line TWT is calculated using the particle-in-cell method. When the operating voltage is 1624 V, this kind of TWT can give 156.5-W output power at 35 GHz, the gain is 21.9 dB, and the electron efficiency is \sim17.7\%. With this kind of TWT as mentioned, the concept of radial integrated angular log-periodic meander-line TWT is proposed, which can provide a new way to obtain higher output power. [ABSTRACT FROM PUBLISHER]