分析了光子晶体谐振腔的模式选择功能,实现光子晶体谐振腔回旋管振荡器高阶电磁模与高次电子回旋模的有效耦合,并成功抑制了模式竞争.通过对光子晶体谐振腔禁带特性的分析,定出了工作模式为TE23模.还建立了光子晶体谐振腔回旋管的等效半径的概念,设计了自洽非线性理论和相关的计算机数值模拟程序.研究发现TE23模能有效地与电子的二次回旋谐波相互作用,其耦合频率为206 GHz,并极大地降低了对工作磁场的要求.在考虑诸多物理因素影响的情况下,对该二次谐波光子带隙谐振腔(PBGC)回旋管振荡器进行了参数优化,得到了电压40 kV、电流4.2A、磁场3.925 T、输出功率35 kW、互作用效率21％的二次谐波TE23模PBGC回旋管振荡器.%A gyrotron oscillator with effective interaction between high-order electromagnetic mode and high electron cyclo-tron mode is achieved through the analysis on mode selectivity of photonic-band-gap cavity(PBGC). By analyzing the characteris-tics of PBGC, TE23 is selected as the operating mode. The concept of equivalent radius for PBGC gyrotron is established and the self-consistent nonlinear theory and related numerical program are completed. The studies show that TE23 mode can interact with second-electronic cyclotron harmonics effectively with the coupling frequency of 206 GHz, and meanwhile reduces the required magnetic field significantly. With the oscillator parameters being optimized accordingly, a second-harmonic PBGC gyrotron oscillator with the wave-beam interaction efficiency of 21% is obtained, when the voltage, current and guiding magnetic field are 40 kV, 4. 2 A and 3. 925 T, respectively.
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