钡钨阴极用大电流低蒸发发射物质的研究

Development of Field Emission Materials with High Current Low Evaporation for Impregnated Cathodes

采用不同工艺制备了浸渍钡钨阴极用的铝酸盐(612),并对其发射性能进行了测试,结果表明,采用二氧化碳烧结的发射物质发射性能最好。利用飞行时间质谱(ToFMS)测试了真空本底、浸渍阴极蒸发物的成分。研究了阴极蒸发速率与阴极温度的关系。比较了不同工艺制备的铝酸盐(612)蒸发速率的大小。

The aluminates of BaO,CaO,AlO,with an empirical molar ratio of 6:1:2,were prepared in different techniques,for impregnated cathodes.The field emission characteristics of the aluminates(612) were evaluated,and its evaporation was characterized with time-of-flight mass spectroscopy(ToFMS),respectively.The influence of its sintering conditions,including the sintering temperature,sintering time and protection gas species,on the cathode performance was studied.The results show that high emission current can be obtained with the aluminates(612),and that the protection gas species in the sintering strongly affects the field emission and evaporation rate of the cathode.For instance,sintering in CO_2 results in the highest emission and the lowest evaporation,whereas in air,the lowest emission and the highest evaporation. The temperature dependence of ion emission current was also studied.