0.22 THz折叠波导行波管输出窗的仿真设计与实验研究

Designof Output Window for 0.22 THz Folded Waveguide Travelling Wave Tube:A Simulation and Experimental Study

输出窗是微波管内将高频能量由高真空环境传送至外部负载的关键部件。本文研究了用于0.22 THz折叠波导行波管的输出窗结构,采用CST微波工作室进行优化计算,设计出窗片材料为蓝宝石的盒型窗结构。分析了结构参数的变化对盒型窗电压驻波比的影响,当盒型窗结构参数在±0.01 mm范围变化时,其驻波比仍低于1.2,保证了零部件加工的可行性。计算了输出结构的损耗包括壁损耗和介质损耗,结合ANSYS软件分析了输出结构上的温度和热应力分布,分析表明:介质窗片的损耗非常小,输出结构的温升主要是由波导壁损耗导致,输出功率为10 W时,窗片最高温度为88.5℃,窗片上最大应力与窗片中心应力差为47.1 MPa,对窗片的结构影响不大。根据优化参数,制备了盒型窗,并且对该结构进行了测试,结果表明,在频率216 GHz处,驻波比为1.24。

Herein,we reported the design optimization with CST microwave studioof the pill-box output win-dow,comprising rectangular and circular waveguides and sapphire disc, for 0.22THz folded waveguide traveling wave tube （ TWT） .The influence ofthe structures,including the sizes of disc and circular waveguide on thewindow＇ s properties,such as the voltage stand wave ratio（VSWR）,power dissipation of circular waveguide wall and sap-phire disc,profiles of temperature and thermal stress,was investigated by ANSYS simulation.We found that the ± 0.01 mm size variations result in a VSWR below 1.2,compatible with the fabrication tolerance.The simulated re-sults show that operating at 10 W,the power mainly absorbed by the wall increased the disc to a highest temperature of 88.5°Cand produced a maximum radial stress difference of 47.1 MPa.The VSWR of the prototyped pill-box win-dow wasmeasured to be 1.24 at 216 GHz.