浸渍式钨酸钡锶阴极的蒸发特性研究

Study on Evaporation Properties of Impregnated Barium-Strontium Tungsten Cathode

采用飞行时间质谱法检测了浸渍式钨酸钡锶阴极(未覆膜)激活时在不同工作温度下的蒸发物成分,并采用石英晶体振荡动态测试法测量了阴极在不同温度下的动态蒸发率。结果表明:浸渍式钨酸钡锶阴极在1100℃左右能够充分激活,且平均蒸发率约为未覆膜612铝酸盐阴极的50%,这有利于发射电流密度提高及阴极寿命延长。

The activation and thermal evaporation behavior of the impregnated barium-strontium tungstate cathode（ uncoated） were investigated with time of flight mass spectroscope and quartz oscillator to understand the possible mechanisms responsible for the enhancement of emission intensity and increase of life-time. The impact of the activation temperature and pressure on the evaporation rate and contents of the evaporated materials was evaluated.The results show that the high temperature significantly affects the activation and evaporate rate of the cathode. To be specific,starting at 1015℃,the evaporate rates of Ba and Ba O increased slowly,shooting up at 1120℃,possibly because of the surface segregation and oxidation of Ba. The impregnated Ba-Sr-W cathode can be fully activated at1100℃,with an average evaporation rate 50% lower than that of the conventional uncoated aluminate cathode.