Equivalent-circuit model of vircators with step circular waveguides
- National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Nuclear Engineering and Engineering Physics
It has been previously shown, both experimentally and via computer simulation, that higher-power microwaves can be generated from vircators with an abrupt discontinuity in circular waveguides. In this work, a rigorous microwave equivalent-circuit model is elaborated to study vircators with step circular waveguides. It makes use of well-defined equivalent voltages and currents for which equivalent circuit representations can be used. In the first part of this work, the authors have determined the empty cavity vircator oscillation modes, i.e., the Q factors, resonance frequencies, and field distributions in an axisymmetric vircator with a waveguide step. Once these oscillation modes are known, the electromagnetic field in the presence of the electron beam can be expanded in terms of them and the Maxwell equations with a localized current source can then be solved to determine the excitation coefficients. In the model, the current distribution can be simply approximated by the two-dimensional particle-in-cell simulation results. By comparing the field structure, the dominant resonant frequency, and the power flow as a function of the distance of the waveguide step, the physical mechanism of power enhancement by vircators with an abrupt discontinuity in circular waveguides can be elucidated.
- OSTI ID:
- 435506
- Report Number(s):
- CONF-960634--
- Country of Publication:
- United States
- Language:
- English
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