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32 results on '"Yao, Yelei"'

5. Experimental Investigation on Trapped Electrons Oscillation Suppression for W-Band Gyro-TWT

Author

Han, Binyang, Jiang, Wei, Wang, Jianxun, Lu, Chaoxuan, Dai, Boxin, Yao, Yelei, Liu, Guo, Xu, Jianhua, and Luo, Yong

Abstract

The fluctuation of current can destroy the performance of the gyrotron traveling-wave tube (Gyro-TWT). We found that the fluctuation of the current is related to the generation of trapped electrons in the interaction circuit. Through experimental and simulation verification, it has been found that the oscillation characteristics of the current are consistent with the motion characteristics of the trapped electrons in the interaction circuit. This indicates that trapped electrons have a significant impact on the current. To suppress the trapped electrons, a novel magnetron injection gun (MIG) with the rear electrode (MSRE) has been designed. The absorbed power of the interaction circuit has decreased by 50%. When a W-band Gyro-TWT with MSRE is operated at 60.5 kV/10.15 A, zero drive with a pulse duration of $200~\mu $ s, and a duty cycle of 15%, there is no current fluctuation. The tube achieves a peak power of 136 kW, a gain of 71 dB, and an average power of 20.54 kW at 94 GHz. The hot test shows that MSRE can suppress the generation of trapped electrons. This greatly enhances the stability of the tube.

Published
2024
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14. A Cascaded W-Band Gyro-TWT With the Configuration of Coaxial and Circular Waveguides

Author

Cao, Yingjian, Liu, Guo, Wang, Yu, Jiang, Wei, Yao, Yelei, Wang, Jianxun, and Luo, Yong

Abstract

To realize a high-gain wideband millimeter-wave amplification, we present and simulate a ${W}$ -band gyrotron traveling wave tube (gyro-TWT) with cascaded coaxial- and circular-waveguide amplifiers. The amplifiers are operated in a coaxial and circular TE01 mode, respectively, and driven by two 60-kV gyrating electron beams with a pitch factor of 1.2 but different beam currents of 1 and 10 A. They are designed to possess relatively low individual gains below all oscillation thresholds to maintain high stability and achieve a high total cascaded gain for the whole gyro-TWT. A coupling circuit is adopted to cascade these two sections, converting the coaxial TE01 mode to the circular one with a −3-dB bandwidth of 6.8 GHz (94.1–100.9 GHz). particle-in-cell (PIC) simulation shows that the designed gyro-TWT can achieve a maximum saturated output power of 239.8 kW at 100 GHz, with a gain greater than 60 dB over a −3-dB bandwidth of 8.0 GHz (94.5–102.5 GHz).

Published
2023
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21. Microwave Measurement of a Compact Circular TE11 Mode Coupler Loaded With Ridges.

Author

Weijie, Wang, Guo, Liu, Jiang, Wei, Wu, Zewe, Yao, Yelei, Pu, Youlei, Wang, Jianxun, and Luo, Yong

Subjects
MICROWAVE measurements, TRAVELING-wave tubes, POWER transmission, CIRCULAR waveguides
Abstract

Design and microwave measurement of a linearly polarized circular TE11 mode coupler are reported in this article. Based on our earlier designed input coupler with smooth wall, we proposed an improved structure with ridges loading resulting in a bandwidth up to 29.2%. Simulation results show the port reflection S11 less than −10 dB is in 7.9–10.6 GHz. And the split transmission S21 and S31are over −3.4 dB in this frequency range. According to the simulation results, the designed input coupler is fabricated and measured with the vector network analyzer. The measurement results show excellent performance, which is in good agreement with the simulation when the conductor loss is taken into consideration. In addition, an input coupler with a cutoff waveguide is designed to improve the efficiency of single-port transmission and the power utilization. Simulation results show the transmission efficiency of the single port achieves 91%. [ABSTRACT FROM AUTHOR]

Published
2021
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30. Design and Simulation of a Broadband $Ka$ -Band Gyrotron Traveling-Wave Tube With a Fully Dielectric-Loaded Circuit.

Author

Li, Hao, Wang, Jianxun, Yao, Yelei, Dong, Kun, Jiang, Wei, Xu, Yong, and Luo, Yong

Subjects
GYROTRONS, CYCLOTRONS, DIELECTRIC devices, ELECTRON beams, DISPERSION (Chemistry)
Abstract

This paper presents the design and simulation of a broadband Ka-band gyrotron traveling-wave tube operating in the $\text {TE}^{d}_{\text {02}}$ mode at the fundamental cyclotron harmonic with a fully dielectric-loaded circuit. Through loading loss-free dielectric on the entire circuit, the dispersion properties of the circuit are changed to maintain resonance condition at a wide frequency band. A sliced lossy dielectric-loaded structure is employed to provide the required loss for stable operation. The interaction circuit is analyzed under the field matching theory, the nonlinear self-consistent theory, and particle-in-cell codes. A saturated peak output power of 100 kW is achieved at 29 GHz, corresponding to a saturated gain of 44 dB and an efficiency of more than 15% within a 3-dB saturated bandwidth of 6.1 GHz (20% relative bandwidth). [ABSTRACT FROM AUTHOR]

Published
2018
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31. Propagation Characteristics of Confocal Waveguides Based on Spheroidal Functions for a W -Band Gyro-TWT.

Author

Yao, Yelei, Wang, Jianxun, Li, Hao, Tian, Qizhi, Dong, Kun, Fu, Hao, and Luo, Yong

Subjects
*SPHEROIDAL functions, *CONFOCAL microscopy, *INTERPOLATION, *FRESNEL function, *GYROTRONS
Abstract

The propagation characteristics of a confocal waveguide are related to the radial spheroidal function, which is extremely complicated. A quadratic polynomial fitting (QPF) expression derived from numerical results by interpolation was successfully applied to the development of confocal gyrotrons. However, the QPF expression is valid only for a moderate spheroidal parameter. As a result, it cannot work well for confocal gyrotron travelling-wave tube (gyro-TWT) applications since the Fresnel parameter may be small for stable operations. For the first time, an efficient algorithm is developed to accurately calculate the spheroidal functions. Based on it, the MATLAB code with high accuracy and efficiency is developed to analyze the propagation characteristics of confocal waveguide. The calculated results and the QPF results are compared for different mirror apertures, and then demonstrated by high frequency structure simulator (HFSS). The calculated results show good agreement with the HFSS results for different mirror apertures while the QPF solution agrees with the HFSS results only for large apertures. The code is valid for arbitrary mirror apertures for both the confocal gyrotron and gyro-TWT applications. [ABSTRACT FROM AUTHOR]

Published
2017
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32. Wideband Circular TE21 and TE01 Mode Converters With Same Exciting Topologies.

Author

Wang, Yan, Wang, Li, Liu, Guo, Shu, Guoxiang, Dong, Kun, Wang, Jianxun, Yan, Ran, Fu, Hao, Yao, Yelei, Luo, Yong, and Wang, Shafei

Subjects
GYROTRONS, TRAVELING-wave tubes, MODE converters, CIRCULAR waveguides, WAVEGUIDES
Abstract

To accurately measure the performance of dielectric loaded circuits for gyrotron traveling wave tubes, a novel topological structure to generate the TE21○ or TE01○ (superscript represents circular waveguide) mode is proposed and verified in this paper. The topology is constituted by an overmoded TE10□ to TE20□ (superscript represents rectangular waveguide) mode converter with multiple matching steps and a taper from TE20□ to TE21○ or TE01○ mode. This topology allows the TE21○ or TE01○ mode to be excited by changing the taper dimensions. Simulation results reveal that the TE21○ and TE01○ mode converters, respectively, have a 1-dB bandwidth of 12.8 and 9.3 GHz with an excellent performance. Converters for the back-to-back millimeter-wave measurements were fabricated with computerized numerical control and wire cutting techniques. Vector network analyzer measurements are in good agreement with the simulations. [ABSTRACT FROM PUBLISHER]

Published
2016
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