Showing papers by "Yanyu Wei published in 2014"
TL;DR: In this paper, a wideband 220 GHz sheet-beam traveling-wave tube (TWT) based on staggered double vane slow-wave structure (SWS) is investigated.
Abstract: 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.
60 citations
TL;DR: In this paper, a ridge-loaded folded waveguide slow-wave structure has been firstly employed to manufacture a W-band continuous wave traveling wave tube (TWT), and the results of the design and experimental test for this TWT were reported.
Abstract: A novel ridge-loaded folded waveguide slow-wave structure has been firstly employed to manufacture a W-band continuous wave traveling wave tube (TWT). This letter reports the processes of the design and experimental test for this TWT. From the experimental results, over 25-W output power are produced within the operation bandwidth from 93.1 to 94.8 GHz, which is in accordance with the simulation results.
21 citations
TL;DR: In this article, a double-grating rectangular waveguide is used as the slow wave structure (SWS) for high power Ka-band electron beam backward wave oscillator, in which a high power sheet beam is used with a cross section of 30 mm.
Abstract: It is attractive to use sheet beam vacuum devices to generate high frequency, high-power microwave radiation. In this paper, we present the numerical and experimental studies of a high-power Ka-band sheet electron beam backward wave oscillator (BWO), in which the double-grating rectangular waveguide is used as the slow wave structure (SWS) for its thermal and mechanical robustness. The fundamental mode of this kind of SWS is an antisymmetric mode which has an antisymmetric longitudinal field distribution and will nonsynchronously interact with the electron beam on two sides of the electron channel along the vertical direction. We put forward a method to overcome this trouble in this paper. To drive this BWO, a high-power sheet beam is used with a cross section of 30 mm $\times\,$ 1 mm. A thin graphite cathode is used for its superiority in producing a high current, high-quality electron beam. For an experimental electron beam of 141 kV and 1668 A, the output power of over 46.8 MW at 31.68 GHz is obtained, which corresponds to a beam–wave interaction efficiency of 19.9%. Compared with the conventional hollow beam BWO and the single-grating rectangular waveguide sheet beam BWO, the double-grating sheet beam BWOs efficiency is higher, which indicates that the double-grating sheet beam device is promising for producing millimeter wave radiation with high power and high efficiency.
15 citations
TL;DR: In this article, a novel slow-wave structure called quasi-parallel-plate (QPP) is proposed for terahertz (THz) backward-wave oscillator BWO design.
Abstract: In this paper, a novel slow-wave structure (SWS), called quasi-parallel-plate (QPP), is proposed for terahertz (THz) backward-wave oscillator BWO design. Compared with the conventional SWSs, the novel SWS has a wider “cold” bandwidth and higher interaction impedance. The Particle-in-cell (PIC) results show that the BWO can produce over 0.82 W output power in the operating frequency range from 0.82 to 1 THz by utilizing an operating voltage range from 5 to 10 kV. The interaction efficiency over the entire operating frequency band is above 2.8%. This SWS, which employing a circular electron beam of 3 mA, can be considered as a promising THz SWS for BWO design with characteristics of moderate operating voltage, wide tunable bandwidth, high efficiency, and compact structure.
10 citations
TL;DR: In this article, a new kind of radial convergent sheet beam electron optical system, which can be used in low voltage Ka-band radial electron devices, is studied, including the beam production, transmission, and focus.
Abstract: A new kind of radial convergent sheet beam electron optical system, which can be used in low voltage Ka-band radial electron devices, is studied in this paper, including the beam production, transmission, and focus. A novel radial high perveance electron gun is proposed, and its volt-ampere characteristics are obtained by means of simulation. The focusing system using permanent magnet rings is put forward, by which a radial uniform magnetic field can be obtained. With the electron gun and focusing system, a 1600 V, 8 A, and 0.04-mm thickness radial convergent sheet beam was produced, and the simulation result shown that it can pass through a 16-mm × 0.06 -mm radial channel 100%.
9 citations
TL;DR: In this article, a phase velocity taper profile incorporating a positive period followed by a negative period is introduced into the design to improve the efficiency of the folded waveguide (FWG) TWT.
Abstract: Folded waveguide (FWG) traveling wave tubes (TWTs) are potential sources of wideband, high-power millimeter and terahertz wave radiation. However, low efficiency limits its application. In this paper, we discuss a design strategy to improve efficiency of the FWG TWT meanwhile how to avoid instability is also discussed. The critical factors for the slow-wave structure design and the sever design are analyzed. A phase velocity taper profile incorporating a positive period followed by a negative period is introduced into the design to improve the efficiency. A Ka-band FWG TWT was developed, which demonstrated the output power up to in 2-GHz bandwidth and electronic efficiency up to .
9 citations
TL;DR: In this paper, two kinds of novel 220 GHz folded-waveguide (FWG) slow-wave structure with different electron-beam tunnels are presented for producing a high power and considerable bandwidth.
Abstract: Two kinds of novel 220 GHz folded-waveguide (FWG) slow-wave structure (SWS) with different electron-beam tunnels are presented for producing a high power and considerable bandwidth. These structures, which have the potential to have a better performance than the conventional FWG SWS, are suitable for circle-beam electron guns and sheet-beam electron guns, respectively. In this study, the electromagnetic characteristics and nonlinear interaction between the electron beam and the electromagnetic field of the two kinds of novel FWG are investigated on the basis of simulation results. The influence of the beam tunnel with respect to its transverse shape and size on the circuit performance is investigated in detail. With different beam tunnels, the two novel FWGs exhibit similar radio-frequency characteristics and signal gain. Particle-in-cell simulation results reveal that the novel tubes exhibit a gain greater than 32 dB and a bandwidth of 10% with a 16.5 kV and 150 mA electron beam and a 90 mW peak input power. Compared with the conventional FWG SWS, the novel FWGs have 32% higher output power under optimized conditions.
8 citations
20 Nov 2014
TL;DR: In this article, the particle-in-cell (PIC) simulation results of a novel Ka-band ring-shaped microstrip meander-line slow-wave structure (SWS) were presented.
Abstract: In this paper, we present the particle-in-cell(PIC) simulation results of a novel Ka-band ring-shaped microstrip meander-line slow-wave structure(SWS). This study shows that, this miniature millimeter-wave power amplifier is capable of delivering an average output power greater than WOW within the bandwidth from 28 to 38 GHz, when the beam voltage and the beam current are 11411Vand 200mA, respectively.
6 citations
TL;DR: In this article, the double-groove loaded folded-waveguide slow-wave structure (SWS) was proposed for millimeter traveling-wave tubes (TWTs) to enhance the strength of beam-wave interaction and improve the performance of gain, the expressions for the dispersion and the interaction impedance of this novel structure are obtained by using matching conditions of the RF fields.
Abstract: To enhance the strength of beam-wave interaction and improve the performance of gain, the double-groove loaded folded-waveguide slow-wave structure (SWS) is proposed for millimeter traveling-wave tubes (TWTs). In the first part, the expressions for the dispersion and the interaction impedance of this novel structure are obtained by using matching conditions of the RF fields. Ansoft HFSS is also used to calculate the high frequency characteristics. The simulation results from HFSS agree with the theoretical results. Numerical calculation for different combinations of the groove width and depth is carried out to study the influence of groove loading on the properties of this novel circuit. In the second part, a linear theory of a double-groove loaded folded-waveguide TWT is developed and calculated for analyzing the effect of groove dimensions on the property of small signal gain. The investigation results indicate that the interaction impedance is obviously raised up and the small signal gain are enhanced by loading groove in the FWSWS.
4 citations
22 Apr 2014
TL;DR: In this article, a S-shaped microstrip meander-line slow wave structure is proposed for millimeter-wave sheet electron beam traveling-wave tube, which has high interaction impedance and wide cold bandwidth.
Abstract: A S-shaped microstrip meander-line slow wave structure is proposed for millimeter-wave sheet electron beam traveling-wave tube The slow wave electromagnetic characteristics are calculated by HFSS The results show that the structure has high interaction impedance and wide cold bandwidth Meanwhile, the transmission loss is very small from the calculations of CST
3 citations
22 Apr 2014
Abstract: This paper presents 140-GHz and 220-GHz folded-waveguide(FWG) traveling wave tubes (TWT) with big electron beam tunnels, whose high frequency characteristics and beam-wave interaction are calculated by using equivalent circuit method and 3-D particle-in-cell (PIC) code. From the calculations, the 140-GHz and 220-GHz big beam-tunnel FWG could produce about 25.36dB and 26.94dB gain respectively under the condition of the uniform slow-wave structure(SWS). And with a proper phase-velocity taper used in 220-GHz FWG, the output power at the center frequency is improved up to 85.7W from 61.74W.
TL;DR: In this article, the authors studied the electromagnetic surface waves along the surface of a finitely thick plate made from negative-index materials and worked out requirements on permeability and permittivity for surface waves to exist.
20 Nov 2014
TL;DR: In this paper, a slow wave structure called sine ridge waveguide (SRWG) was proposed for a wideband high-power terahertz radiation source, which can produce over 0.4W continuous wave power output in a frequency range from 0.6294THz to 0.6766THz.
Abstract: A novel slow wave structure (SWS) called sine ridge waveguide (SRWG) has been proposed for a wideband high-power terahertz radiation source. The cold bandwidth of the SRWG is similar to the sine waveguide structure. Meanwhile, the interaction impedance of the SRWG is about 70% higher than sine waveguide at 0.65THz with the same dimensional parameters. Furthermore, it possesses low ohmic losses and reflection as sine waveguide ranging from 0.62THz to 0.68THz and could be applied to 0.65THz BWO. Finally, the particle-in-cell simulation method is used to predict its radiation performance. The results shows that the novel backward wave oscillator can produce over 0.4W continuous wave power output in a frequency range from 0.6294THz to 0.6766THz.
22 Apr 2014
TL;DR: In this article, an open-sided periodic cusped magnetic (PCM) focusing through theoretically analyzed the transport characteristic of the elliptical sheet beam was proposed, and it was shown that the beam with transverse size 5 mm×0.4 mm can move through the beam tunnel in the axial distance 180 mm under the opensided PCM focusing without the "Diocotron" instability.
Abstract: In this paper, we have proposed an open-sided periodic cusped magnetic (PCM) focusing through theoretically analyzed the transport characteristic of the elliptical sheet beam. It is shown that the elliptical sheet beam with transverse size 5 mm×0.4 mm can move through the beam tunnel in the axial distance 180 mm under the open-sided PCM focusing without the “Diocotron” instability.
22 Apr 2014
TL;DR: In this paper, the authors proposed a 140 GHz slow-wave structure, consisting of an improved array of half-period-staggered double-vane, which is suitable for the millimeter-wave sheet beam traveling-wave tubes (TWTs).
Abstract: In this paper, we have proposed a 140 GHz slow-wave structure, consisting of an improved array of half-period-staggered double-vane. This structure is suitable for the millimeter-wave sheet beam traveling-wave tubes (TWTs). Numerical results from HFSS simulations clearly demonstrate that there is the better high-frequency characteristics at frequencies from 130 to 150 GHz for the slow-wave structure.
20 Nov 2014
TL;DR: In this paper, a square helix slow wave structure is proposed for high gain millimeter wave TWTs, which holds higher interaction impedance and lower normalized phase velocity, which indicates higher output power and lower operating voltage in application of millimeter-wave TWTs.
Abstract: A square helix slow wave structure is proposed for high gain millimeter wave TWTs. The electromagnetic characteristics of this structure are calculated by HFSS. It is shown that, compared with the equivalent circular helix with the same cross section perimeter, the square helix structure holds higher interaction impedance and lower normalized phase velocity, which indicates higher output power and lower operating voltage in application of millimeter-wave TWT.
22 Apr 2014
TL;DR: A folded rectangular groove waveguide (FRGWG) slow wave structure for 140 GHz traveling wave tube (TWT) has been investigated in this article, where the radio frequency characteristics and beam-wave interaction of the structure are calculated.
Abstract: A folded rectangular groove waveguide (FRGWG) slow wave structure (SWS) for 140 GHz traveling wave tube (TWT) has been investigated in this paper. The radio frequency characteristics and beam-wave interaction of the structure are calculated. The calculation results show that such amplifier can potentially be used in high power millimeter/THz wave radiation source, and a large dimension circle electron beam tunnel is suit for this structure.
22 Apr 2014
TL;DR: In this article, the authors gave a numerical instability analysis of a high power Ka-band rectangular double-grating sheet beam backward wave oscillator, which can generate a pulsing microwave power of 46.8MW but with a degree of instability.
Abstract: This paper gives a numerical instability analysis of a high power Ka-band rectangular double-grating sheet beam backward wave oscillator (BWO). In the experiment, this BWO can generate a pulsing microwave power of 46.8MW but with a degree of instability. This simulation analysis can provide some significance for guiding the experiment.
22 Apr 2014
TL;DR: In this article, three types of folded waveguide slow-wave structure (SWS) are analyzed and compared for 140GHz traveling wave tube (TWT) and compared the radio frequency characteristics and the large signal beam-wave interaction performances of the three SWS are simulated and compared.
Abstract: Three types of folded waveguide slow-wave structure (SWS) are analyzed and compared for 140GHz traveling wave tube (TWT). The radio frequency characteristics and the large signal beam-wave interaction performances of the three SWS are simulated and compared. The loaded ridge can improve the output power and the tapered ridge can reduce the mismatch between the SWS and the ridge.
20 Nov 2014
TL;DR: In this article, a U-shaped quasi-parallel-plate (QPP) slow wave structure for 1 THz backward wave oscillator was investigated, and the radio frequency characteristics and beam-wave interaction of the structure were calculated.
Abstract: A U-shaped quasi-parallel-plate (QPP) slow wave structure (SWS) for 1 THz backward wave oscillator (BWO) has been investigated in this paper. The radio frequency characteristics and beam-wave interaction of the structure are calculated. The results show that such BWO can operated at a low voltage (<; 10 kV), and potentially be used in THz wave radiation source.
22 Apr 2014
Abstract: A sheet beam electron gun focused by a periodic elliptic magnetic field is designed in this paper. And the periodic elliptic magnetic field has successfully been designed and fabricated. The experimental results show that the measured and the simulated axial magnetic field coincide well.
22 Apr 2014
TL;DR: In this paper, the authors theoretically analyzed the transverse magnetic modes on the surface of a finitely thick negative-index materials (NIM) plate, and examined theoretical predictions with particle-in-cell simulations.
Abstract: It has been shown that stringent requirements on permeability and permittivity are needed for surface waves to exist on the surface of the vacuum and the medium made from negative-index materials (NIM). In this paper, we theoretically analyzed the transverse magnetic modes on the surface of a finitely thick NIM plate, and examined theoretical predictions with particle-in-cell simulations. The results are in agreement and show that the requirements could be released.
01 Dec 2014
TL;DR: In this paper, the authors describe the design of an X-band coupled-cavity traveling-wave tube (CC-TWT) based on the ridgeloaded staggered single-slot rectangular coupled-Cavity slow wave structure (SWS) using High Frequency Structure Simulator (HFSS) and particle-in-cell (PIC) code in Computer Simulation Technology (CST) Particle Studio.
Abstract: The paper describes the design of an X-band coupled-cavity traveling-wave tube (CC-TWT) based on the ridge-loaded staggered single-slot rectangular coupled-cavity slow wave structure (SWS) using High Frequency Structure Simulator (HFSS) and particle-in-cell (PIC) code in Computer Simulation Technology (CST) Particle Studio The working frequency range is from 86 to 95 GHz The ridge can concentrate the longitudinal electric field in the structure so that the CC-TWT can produce 296 kW of saturated output power at 9 GHz with an electronic efficiency of 223 percent and a gain of 447 dB when the beam voltage is set to 269 kV and the beam current is set to 5 A