TM_(11)模对大功率微波输出窗热损耗及耐热性能的影响

Influence of TM_(11)-Mode on RF-Losses and Heat-Resistance of High-Power Microwave Output Windows

基于一S波段圆柱盒型输出窗的电磁仿真与高频介质损耗计算,结合ANSYS软件对窗片温度与热应力分布模拟,探讨高次模式对输出窗热损耗与耐热性能方面的影响。结果表明,存在于窗片表面的TM11模可能加剧输出窗的热损耗,增大窗片承受的温度梯度和热应力,从而导致输出窗的耐热性能与平均功率耐受能力下降。

The interaction of high-order cylindrical waveguide modes and pill-box high power microwave output win- dow was theoretically analyzed and numerically simulated with software package ANSYS to evaluate the distributions of temperature and thermal stress of the surface of output window. The influence of TEn-and TMn-modes on the RF-losses and heat resistance of the window disk was investigated. The simulated results show that TMn-mode significantly increases the temperature and thermal stress of the window. For example,at a peak output power of 1.8 MW （an average output power of 50 kW）, TMn mode increases the heat-loss from 67.5 to 88.6 W and an average temperature from 102.9 to 133.9~C ,compared with TEn-mode;and the largest thermal stress locate at the upper and lower edges of the window,co- inciding with the highest electric field and temperature gradient. The TMn-mode induced thermal stress explains the deterioration of heat-resistance of the window at a high output power. Possible solution of the problem was also tentatively discussed.