利用3维高频软件对大间隙速调管输出腔及其同轴提取波导金属支撑杆进行了高频分析，建立了带双排金属支撑杆的大间隙输出腔3维结构模型，采用3维PIC程序对该输出腔的提取效果进行了粒子模拟。研究结果表明：作为输出腔同轴提取波导支撑的第二排支撑杆，和兼作输出腔腔壁的第一排支撑杆，都会影响输出腔的高频谐振特性，因此必须结合大间隙输出腔进行一体化设计；此时同轴提取波导支撑杆设计的基本原则不以追求最高的TEM模式传输效率为目的，而是通过控制双排支撑杆的散射特性，得到合适的外部品质因数和间隙电场强度。在注入电功率约2.9 GW，束流调制深度90%时，设计的带双排支撑杆的3.6 GHz大间隙输出腔结构，可提取约1.06 GW的平均功率，效率约36.5%。

An output cavity with double-rows of metal posts for a wide-gap klystron amplifier (WKA) is built and simulated using the three-dimension fully electromagnetic particle-in-cell (PIC) code and high frequency analysis software. The results show that both the first row and the second row of posts affect the high frequency characteristics of the output cavity, thus the double-rows of posts must be designed together with the output cavity, and the design purpose is to obtain proper external quality factor and gap electric field through controlling the posts’ scattering characteristic. Under the electric power of 2.9 GW and the electron beam modulation depth of 90%, a microwave power of 1.06 GW with an average power efficiency of about 36.5% is obtained at 3.6 GHz from an output cavity with double rows of posts designed according to the rules mentioned above.