Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

In this paper, an interesting type of a two-section folded wave-guide (TSFW) slow wave structure (SWS) for the development of sub-Terahertz (sub-THz) extended interaction oscillator (EIO) is proposed. In this sub-THz device, the prebunching electron beam is produced by the TSFW SWS, which results in the enhancement of the output power. To verify this concept, the TSFW for sub-THz EIO is developed, which includes the design, simulation, and some fabrications. A small size of electron optics system (EOS), the TSFW SWS for beam-wave interactions, and the output structure are studied with simulations. Through the codes Egun and Superfish, the EOS is designed and optimized. With a help of CST studio and 3D particle-in-cell (PIC) simulation CHIPIC, the characteristics of beam-wave interaction generated by the TSFW are studied. The results of PIC simulation show that the output power is remarkably enhanced by a factor of 3, which exceeds 200 W at the frequency of 108 GHz. Based on the optimum parameters, the TSFW is manufactured with a high speed numerical mill, and the test transmission characteristic |S21| is 13 dB. At last, the output structure with a pill-box window is optimized, fabricated, integrated, and tested, and the result shows that the voltage standing-wave ratio of the window is about 2.2 at an operating frequency of 108 GHz. This design and simulation can provide an effective method to develop high power THz sources.

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Design and simulation of a sub-terahertz folded-waveguide extended interaction oscillator

Liu

Zhang

Zhao

et al. 2017

Physics of Plasmas

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Study of rectangular beam folded waveguide traveling-wave tube for terahertz radiation

Zhang

Grieser

et al. 2017

Physics of Plasmas

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To gain higher power with a lower cathode current density and a simpler structure, a novel rectangular beam folded waveguide traveling-wave tube (RB-FW-TWT) operating at 220 GHz is proposed and analyzed in this paper and compared with the normal circular beam (CB) FW TWT. The dispersion characteristic was investigated based on an equivalent circuit model. The interaction impedance and the S-parameter of a RB-FW traveling-wave tube were analyzed by numerical simulations. A 3-D particle-in-cell code CST particle studio was introduced to analyze the performance of RB-FW TWT. The influence of the initial electron energy, frequency, input power, guiding magnetic field, and aspect ratio of the RB tunnel on the circuit performance was observed, and physical explanations were given. It reveals that the output power of RB-FW can reach 51.1 dBm, 8.4% dBm higher than a CB-FW, with a 3 dB bandwidth of 35 GHz when the beam voltage and current are set to 14.25 kV and 140 mA, respectively. An aspect ratio of 0.4 is recommended to optimize the high-frequency properties and circuit performance

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Nonlinear theory for beam-wave interactions of two electron beams with higher order TE20 mode in serpentine waveguide traveling wave amplifier

Liu

Gao

et al. 2018

Physics of Plasmas

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In this study, a nonlinear model is presented, which is used to analyze the beam-wave interaction of two electron beams with a higher TE20 mode in a serpentine waveguide (SW) traveling wave tube (TWT). Taking advantage of the novel model, the dimensions of SW are enlarged and the difficulties of fabrications of SW are reduced. To investigate the characteristics of two electron beams interacting with a high order mode in SW, the disk theory is used, in which the RF field in gap, space charge field, and the electron motion equations are combined, and the reactions of two electron beams to wave are considered. The nonlinear characteristics of power saturations, the distributions of electron velocity, and phase space are studied. To verify the validity of the nonlinear model, the theoretical results are compared with those of particle-in-cell simulations, and the output powers versus beam voltage and exciting frequency are studied. The results show that the relative errors are less than 10%, which are suitable for solving the SW-TWT operation characteristics.

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Enhancement of the output power of terahertz folded waveguide oscillator by two parallel electron beams

Cited by 10 publications

References 18 publications

Design and simulation of a sub-terahertz folded-waveguide extended interaction oscillator

Design and simulation of a sub-terahertz folded-waveguide extended interaction oscillator

Study of rectangular beam folded waveguide traveling-wave tube for terahertz radiation

Nonlinear theory for beam-wave interactions of two electron beams with higher order TE20 mode in serpentine waveguide traveling wave amplifier

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