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Enormous concerns focus on the high-power and wide bandwidth traveling-wave tube (TWT) for its outstanding performance. In this article, a shape-optimized staggered double-vane slow-wave structure (SWS) for terahertz (THz) sheet beam TWT is proposed. The shape-optimized staggered double-vane SWS takes the advantages of higher interaction impedance, lower transmission loss, and lower phase velocity than conventional staggered double-vane SWSs. The shape-optimized staggered double-vane SWS with 85 periods is designed, fabricated, and cold tested. The measured transmission loss of the shape-optimized staggered double-vane SWS is less than 0.79 dB/cm in the frequency range of 0.211–0.26 THz, which is in good agreement with the simulation results. Furthermore, the beam–wave interaction analysis of a sheet beam TWT with this SWS is given. The output power is predicted to be >100 W with 3-dB bandwidth of >50 GHz. The results show that the shape-optimized staggered double-vane SWS is a very promising scheme to construct a high-power and wideband THz TWT for future applications such as communication and imaging. [ABSTRACT FROM AUTHOR]

The angular log-periodic meander-line traveling wave tube (TWT) is a kind of low voltage, small-sized, high power, low cost, on chip amplifiers, and considered as a key part of the advanced communication systems, the future biomedical applications and the next electronic counter measure (ECM) instruments et al. Here, an angular log-periodic meander-line TWT is presented in this article. The angular log-periodic meander-line slow wave structure (SWS) is supported by two diamond rods. The dispersion and the impedance characteristics are analyzed in detail. In order to reduce the reflection loss, a gradual ridged waveguide is connecting the input–output standard rectangular waveguide to the meander-line SWS. The particle in cell (PIC) simulations show that the output power of the TWT can reach 55 W at 34 GHz with the operation voltage of 1800 V and the beam current of 0.2 A. The SWS is manufactured by a laser machine with Molybdenum sheet. The assembled TWT is tested and the results show that the ${S}_{{11}}$ is less than −10 dB at 30–39 GHz. The ${S}_{{21}}$ mismatch between the simulated and the measurement is discussed at the end. [ABSTRACT FROM AUTHOR]

A novel sine groove waveguide slow wave structure (SGW-SWS), originated from the sine waveguide (SW), is proposed for a wideband terahertz (THz) traveling wave tube (TWT). SGW-SWS not only has high interaction impedance in a relatively wide frequency band, but also has a wide beam tunnel. In addition, it can be fabricated using the Nano-Computer Numerical Control (CNC) milling techniques. The high-frequency simulation results show that, under the same dispersion, the passband of SGW-SWS is 23 GHz wider than that of SW-SWS, and the average interaction impedance of SGW-SWS is higher than that of SW-SWS in the whole passband. And the transverse dimension of beam tunnel is independent of the dispersion characteristics of SGW-SWS, so the beam current can be further increased by enlarging the size of beam tunnel. Moreover, the particle-in-cell (PIC) simulation results reveal that the saturated power and electronic efficiency of SGW-TWT in the frequency range of 201–260 GHz are more than 84.9 W and 2.72%, respectively, when the operating voltage is 20.8 kV and the beam current is 150 mA. [ABSTRACT FROM AUTHOR]

In this article, a novel dielectric-supported staggered dual-meander-line (DS-SDML) planar slow-wave structure (SWS) is proposed for a traveling wave tube (TWT) working at ${E}$ -band. The proposed staggered arrangement of meander-lines (MLs) leads to a stronger beam–wave interaction and achieves higher output power as compared to the symmetric arrangement. The input–output couplers have been designed by using staggered stepped double ridge waveguide, to connect the standard ${E}$ -band rectangular waveguide and the DS-SDML SWS. An attenuator and pitch tapering have been applied to the proposed SWS to suppress the unwanted frequencies and to improve the output power. Particle-in-cell (PIC) simulation results show that for an 11.8-kV, 200-mA sheet-beam, the output power can reach 283 W at 75 GHz, with a maximum gain and electronic efficiency of 34.5 dB and 11.9%, respectively. [ABSTRACT FROM AUTHOR]

A novel slow wave structure (SWS), named staggered double corrugated waveguide (SDCW), is proposed for the development of wideband high-power terahertz (THz) traveling wave tubes (TWTs). The SDCW-SWS not only has the wideband characteristic of staggered double grating (SDG) but also has the high interaction impedance characteristic of symmetrical double grating. In addition, its tunnel width is independent of the lower cutoff frequency and can be further increased. Numerical Eigen mode calculations show that, under the same dispersion, the passband of SDCW-SWS is increased by more than 10 GHz compared with SDG-SWS, and the average interaction impedance at 195 GHz is increased by about 62%. A particle-in-cell simulation analysis confirms that the average output power, saturated gain, and electron efficiency of SDCW-TWT at 195 GHz are ~110 W, ~20.34 dB, and ~5.46%, respectively, when the operating voltage is 20 kV and the beam current is 100 mA. Therefore, SDCW is a promising slow wave circuit of wideband high-power THz traveling wave amplifier. [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]

The symmetrical microstrip angular log-periodic meander-line (ALPML) slow-wave structure (SWS), which is suitable for Ka-band low-voltage traveling-wave tubes, is described in this paper. The dispersion characteristics and coupling impendence of this kind of SWS are achieved by simulation. A radial uniform magnetic field of 0.4 T is developed using radially magnetized permanent magnets to focus the radial sheet electron beam. To exploit the potentialities of the symmetrical ALPML SWS, the beam–wave interaction is carried out with a radial convergent and a divergent sheet electron beam. For the radial divergent electron beam with a voltage of 791 V and a current of 0.3 A, an output power over 60 W with an electron efficiency of 26% at 30 GHz is achieved from particle-in-cell simulation. The effects of misalignments and phase mismatches are carried out at the end. [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]