Showing papers by "Yanyu Wei published in 2020"
TL;DR: In this paper, a sensitivity analysis was performed on the potential influencing factors for the performance of the flat-roofed sine waveguide (SWG) slow wave structure (SWS).
Abstract: The $W$ -band flat-roofed sine waveguide (SWG) slow wave circuit was designed and processed in this article. Considering the limitations on present practical fabrication level, sensitivity analysis was performed on the potential influencing factors for the performance of the flat-roofed SWG slow wave structure (SWS). As indicated by the calculation results, the gap between the SWSs and the side-wall strips could have a significant impact on the dispersion, interaction impedance, and the transmission of the entire slow wave circuit. Based on the theoretical analysis, two types of $W$ -band flat-roofed SWG slow wave circuits were fabricated and tested. The side-wall strips of the two circuits are processed with/without rounded corner. The circuit without rounded corner may cause a large gap and severe reflection. In comparison, the other one with rounded corners can make the parts fit tighter, thus minimizing the potential gap. The test results demonstrate that the $W$ -band flat-roofed SWG traveling-wave tube (TWT) possesses a voltage standing wave ratio less than 1.8, which is basically consistent with the simulation results.
10 citations
TL;DR: In this paper, 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).
Abstract: 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.
5 citations
TL;DR: In this paper, a potentially pseudoperiodic slow wave structure (SWS) for a broadband, high-power, helix traveling-wave tube (TWT) is studied.
Abstract: In this article, a potentially pseudoperiodic slow wave structure (SWS) for a broadband, high-power, helix traveling-wave tube (TWT) is studied. The structure considered here suppresses the back-wave oscillations caused by a large working current. These oscillations do not have conventional uniform pitch distributions in the radial dimension; rather, the two configurations studied in this article are a uniform pitch gradient and a conical helix. Through a reasonable design and a large number of calculations, the entire tube consists of four tapered, pitch-varying SWSs. In addition, to achieve an 8–18-GHz broadband, high-power output, a double-ridged waveguide window output coupler is designed, fabricated, and tested. The 3-D electromagnetic simulation software CST STUDIO SUITE is used to verify the performance of the tube. The simulation results show that the potentially pseudoperiodic SWS can adequately suppress the backward-wave oscillations, and the tube is capable of achieving an output power of over 6 kW, even with a very wide bandwidth of 8–18 GHz. Additionally, the electronic efficiency varies from 21.5% to 25.8%. The maximum output power is 7.45 kW, corresponding to an electronic efficiency of 25.8% at 14 GHz.
3 citations
2 citations
19 Oct 2020
TL;DR: In this paper, a 0.67THz sheet electron beam traveling-wave tube based upon sine waveguide slow-wave structure is studied and the high frequency characteristics and transmission characteristics are calculated by a 3D high frequency simulation software.
Abstract: A 0.67THz sheet electron beam traveling-wave tube based upon sine waveguide slow-wave structure is studied. In this paper, the high frequency characteristics and transmission characteristics are calculated by a 3-D high frequency simulation software. The beam-wave interaction is also simulated. From the simulation results, the peak output power is 1.7W ranging from 0.65THz to 0.69THz with synchronous voltage of 17kV, operation current of 10mA and input power of 3.2mW.
2 citations
19 Oct 2020
TL;DR: In this paper, a fan-shaped metal loaded helix traveling wave tube working at the Ka-band was described, which has gain of 37.3-48.7dB, electronic efficiency of 15.18-19.42% and output power is greater than 286W when it works at a voltage of 9KV and a current of 210mA.
Abstract: This paper describs a fan-shaped metal loaded helix traveling wave tube working at Ka–band. It has the gain of 37.3-48.7dB, electronic efficiency of 15.18%-19.42% and output power is greater than 286W when it works at a voltage of 9KV and a current of 210mA. The simulation results of VSWR for its coaxial energy coupler are below 1.35, and the test results of it is below 2.1 at the working frequency range.
2 citations
TL;DR: In this paper, two types of compact and effective input and output couplers for a 6-18 GHz 5-kW-level helix traveling wave tube (TWT) are designed, fabricated, and cold- tested.
Abstract: In this article, two types of compact and effective input and output couplers for a 6–18 GHz 5-kW-level helix traveling wave tube (TWT) are designed, fabricated, and cold- tested. The input coupler section includes an impedance transformer, a conical coaxial window, and a transition to a subminiature version A (SMA) connector for a radio frequency (RF) input. For achieving a high-power output, a new type of double-ridged waveguide window is used in the output coupling section. The output coupling structure consists of a standard double-ridged waveguide (WRD650), an impedance transformer, a square sapphire window, and a coaxial to double-ridged waveguide transition. The commercially available 3-D electromagnetic simulation software package CST is used to further optimize these structures, including couplers terminated with an actual complex helix slow-wave structure (SWS). According to the simulation results, the input and output couplers are fabricated and tested. The experimental results of the optimized coupled structures are presented, and both couplers show excellent transmission performance for a 6–18-GHz high-power helix TWT.
2 citations
07 Dec 2020
TL;DR: In this article, a classical optimization algorithm named L-BFGS is proposed to simulate the thermal behavior of electron gun for terahertz traveling-wave tubes, which is a variation of Quasi-Newton optimization method, expert in dealing with unconstrained optimization problems while keeping the stability of the calculation.
Abstract: In this article, we propose a classical optimization algorithm named L-BFGS to simulate the thermal behavior of electron gun for terahertz traveling-wave tubes. The L-BFGS algorithm, as a variation of Quasi-Newton optimization method, expert in dealing with the unconstrained optimization problems while keeping the stability of the calculation. Efficiency and accuracy of L-BFGS algorithm are verified by modeling the thermal behavior of an actual electron gun on MATLAB platform successfully with no breakdown. According to the simulation results, this method performs better than some reference methods in terms of computational memory usage and time cost. Our numerical conclusions indicate that it is promising for thermal analysis of electron gun, which would be useful for researchers during the design phase.
1 citations
13 Dec 2020
TL;DR: In this paper, a V-shaped double-staggered grating waveguide was proposed to achieve a saturated gain of 28.24dB in a traveling wave tube based on this new structure.
Abstract: A novel slow wave structure, called the V-shaped double-staggered grating waveguide,has been presented in this paper. the simulation results reveal that the V-shaped double-staggered grating structures require a lower operating voltage in comparison with double-staggered grating structures. The traveling wave tube based on this new structure was predicted to have a saturated gain of 28.24dB.
1 citations
19 Oct 2020
TL;DR: In this paper, a high-stability electron optical system for millimeter wave traveling wave tubes is presented, where a circular electronic injection Pierce electron gun is designed and the electron channel radius is 0.2mm, the current is 90mA.
Abstract: This paper introduces a high-stability electron optical system for millimeter wave traveling wave tubes. Firstly, a circular electronic injection Pierce electron gun is designed. The electron channel radius is 0.2mm, the current is 90mA. Then the immersed flow method was used to design a ppm focusing system with a magnetic field period of 7.3 mm and a peak value of 4900 Gauss. The stability of the immersed flow electron gun is compared with the gun under a conventional ppm magnetic field in consideration of thermal deformation and assembly errors.
19 Oct 2020
TL;DR: In this paper, the high frequency characteristics of Trapezoidal Staggered Grating Slow-wave Structure for 1THz Traveling Wave Tube has been studied, the transmission structure has been simulated, the reflection coefficient is less than -20dB in the frequency of 1015GHz to 1055GHz and the loss of the structure is over 58dB.
Abstract: In this paper, the high frequency characteristics of Trapezoidal Staggered Grating Slow-wave Structure for 1THz Traveling Wave Tube has been studied. The transmission structure has been simulated, the reflection coefficient is less than -20dB in the frequency of 1015GHz to 1055GHz and the loss of the structure is over 58dB. The PIC simulation shows that the saturation output power is 405mW at the frequency of 1030GHz, and the corresponding gain is 19.08dB.
19 Oct 2020
TL;DR: The high frequency characteristics and beam wave interaction characteristics of a Ka-band (26-40GHz) helix traveling wave tube (TWT) with rectangular semi-metallic rod are presented in this article.
Abstract: The high frequency characteristics and beam wave interaction characteristics of a Ka-band (26-40GHz) helix traveling wave tube (TWT) with rectangular semi-metallic rod are presented. The design results show that the TWT has the gain of more than 42dB, the output power of more than 220W and the electronic efficiency of more than 19% in the working bandwidth. Now the high frequency structure of the TWT are manufactured, the preparation for the transmission test is in progress.
19 Oct 2020
TL;DR: In this article, a W-band multi-beam traveling-wave tube (TWT) based on sine slow-wave structure is designed, and the cold bandwidths of the fundamental and higher-order modes in the slowwave circuit are analyzed using HFSS software.
Abstract: A W-band multi-beam traveling-wave tube (TWT) based on sine slow-wave structure is designed. The cold bandwidths of the fundamental and higher-order modes in the slow-wave circuit are analyzed using HFSS software. Through reasonable structural design, the fundamental mode and low-order mode are suppressed. The beam-wave interaction capability of the multi-beam TWT is analyzed based on the high-order mode transmission design. At the voltage of 11.7 kV, the current density of the sheet electron beam is 96 A/cm2 which can be produced by the non-convergent electron gun, and the output power is over 150 W in the operating frequency 90 GHz-100 GHz.
19 Oct 2020
TL;DR: In this article, a low-voltage backward wave oscillator based on staggered double vane structure is designed and a novel straight-waveguide input/output coupler is also proposed.
Abstract: A low-voltage backward wave oscillator based on staggered double vane structure is designed in this paper and a novel straight-waveguide input/output coupler is also proposed. The high-frequency characteristics and transmission characteristics of the structure are calculated and the results of the circuit show that the reflection coefficient is below -10dB in the frequency range of 250-300GHz. The beam-wave interaction is also carried out and the output power is greater than 20mW within the frequency range of 290GHz to 300GHz, which the corresponding operating voltage is 3800V to 4500V. And a maximum output power of 2W is reached at 300GHz.