中国物理B ›› 2015, Vol. 24 ›› Issue (6): 60701-060701.doi: 10.1088/1674-1056/24/6/060701

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Theoretical models for designing a 220-GHz folded waveguide backward wave oscillator

蔡金赤a b, 胡林林b, 马国武b, 陈洪斌b, 金晓b, 陈怀璧a   

  1. a Department of Engineering Physics, Tsinghua University, Beijing 100084, China;
    b Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621000, China
  • 收稿日期:2014-09-16 修回日期:2014-12-15 出版日期:2015-06-05 发布日期:2015-06-05
  • 基金资助:
    Project supported by the Innovative Research Foundation of China Academy of Engineering Physics (Grant No. 426050502-2).

Theoretical models for designing a 220-GHz folded waveguide backward wave oscillator

Cai Jin-Chi (蔡金赤)a b, Hu Lin-Lin (胡林林)b, Ma Guo-Wu (马国武)b, Chen Hong-Bin (陈洪斌)b, Jin Xiao (金晓)b, Chen Huai-Bi (陈怀璧)a   

  1. a Department of Engineering Physics, Tsinghua University, Beijing 100084, China;
    b Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621000, China
  • Received:2014-09-16 Revised:2014-12-15 Online:2015-06-05 Published:2015-06-05
  • Contact: Cai Jin-Chi E-mail:caijinchino1@163.com
  • About author:07.50.-e; 07.57.Hm
  • Supported by:
    Project supported by the Innovative Research Foundation of China Academy of Engineering Physics (Grant No. 426050502-2).

摘要: In this paper, the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide (FW) backward wave oscillator (BWO) are described. On the whole, these equations are mainly classified into small signal model (SSM), large signal model (LSM), and simplified small signal model (SSSM). Using these linear and nonlinear one-dimensional (1D) models, the oscillation characteristics of the FW BWO of a given configuration of slow wave structure (SWS) can be calculated by numerical iteration algorithm, which is more time efficient than three-dimensional (3D) particle-in-cell (PIC) simulation. The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently. The dispersion characteristics of the FW are obtained by equivalent circuit analysis. The space charge effect, the end reflection effect, the lossy wall effect, and the relativistic effect are all considered in our models to offer more accurate results. The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated. The 3D PIC method is adopted to verify the theoretical design results, which shows that they are in good agreement with each other.

关键词: terahertz, folded waveguide, backward wave oscillator, theoretical models

Abstract: In this paper, the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide (FW) backward wave oscillator (BWO) are described. On the whole, these equations are mainly classified into small signal model (SSM), large signal model (LSM), and simplified small signal model (SSSM). Using these linear and nonlinear one-dimensional (1D) models, the oscillation characteristics of the FW BWO of a given configuration of slow wave structure (SWS) can be calculated by numerical iteration algorithm, which is more time efficient than three-dimensional (3D) particle-in-cell (PIC) simulation. The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently. The dispersion characteristics of the FW are obtained by equivalent circuit analysis. The space charge effect, the end reflection effect, the lossy wall effect, and the relativistic effect are all considered in our models to offer more accurate results. The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated. The 3D PIC method is adopted to verify the theoretical design results, which shows that they are in good agreement with each other.

Key words: terahertz, folded waveguide, backward wave oscillator, theoretical models

中图分类号:  (Electrical and electronic instruments and components)

  • 07.50.-e
07.57.Hm (Infrared, submillimeter wave, microwave, and radiowave sources)