微波电真空器件用热阴极的温度测量

Temperature measurement of cathodes used in microwave vacuum electron devices

利用红外测温仪、光学测温仪、热电偶测温仪(铂铑-铂)对微波电真空器件用浸渍阴极表面、覆膜阴极表面、阴极侧面(钼筒)进行了温度对比测试研究。结果表明:采用红外测温仪和光学测温仪测试浸渍阴极表面的温度与采用热电偶测温仪测试的温度相差不大,而覆膜阴极却相差约50℃;采用红外测温仪和光学测温仪测试阴极侧面(钼筒)的温度相差不大,都低于热电偶测温仪测试的温度约60℃,这说明红外和光学测试温度值低于阴极的实际温度(热电偶测量值)。由于在阴极表面出现了物理、化学变化,红外测温仪和光学测温仪测试的阴极表面温度值在1150℃左右加热100min内增加约30℃。分析认为这些差异主要是因为覆膜阴极的表面与浸渍阴极的表面及阴极侧面(钼筒)的发射系数不同造成的,当然测试结果也会随着这些因素的变化而有一定的变化。

Microwave vacuum devices are used in a wide variety of areas,such as radar,space technology,electron accelerators,free electron lasers.The cathodes,i.e.the electron sources,are the cores of high-power microwave sources.Their performances directly determine the output power,lifetime and other properties of the microwave sources.It is necessary to know the actual temperature of a thermionic cathode.The temperatures of an impregnated cathode,a coated cathode and a cathode side(molybdenum tube)have been tested by infrared thermometer,optical pyrometer and thermocouple thermometer(platinum and rhodium-platinum).The results show that the temperature of an impregnated cathode tested by infrared thermometer and optical pyrometer is similar to that by thermocouple thermometer,so the temperatures of impregnated cathode tested by infrared thermometer and optical pyrometer are very close to the actual temperature by thermocouple thermometer.The temperatures of coated cathode tested by infrared thermometer and optical pyrometer are lower than the actual temperature of the cathode tested by thermocouple thermometer about 50 ℃.The temperatures of the cathode side(molybdenum tube)tested by infrared thermometer and optical pyrometer are lower than the actual temperature of the cathode by thermocouple thermometer about 60℃.Since the physical and chemical changes arise on the cathode surface,the temperatures of the cathode surface tested by infrared thermometer and optical pyrometer increase about 30℃ heated at about 1150℃ within 100 min.These results will be affected by the molybdenum processing technology on the surface of the material,coating material,thickness of the film,the film density and other factors.Infrared thermometer and optical pyrometer are strongly dependent on the thermal radiation coefficient of the test surface,and it is very difficult to accurately obtain the thermal radiation coefficient of some materials.