STUDY ON EMISSION PROPERTIES OF La-WC CATHODE AND ITS RESISTANCE TO POISONING OF OIL VAPOUR
对镧-碳化钨阴极发射大和抗油蒸汽中毒的探讨

In this paper, an assupmtion to explain emission properties of the La-WC cathode and its resistance to poisoning of oil vapour is presented and was demonstrated by experiments. In the operating temperature range of the La-WC cathode, lanthanum would react chemically with tungsten carbide and form La2C3. La2C3 is a kind of good emissive material with a work function approximate to lanthanum's and can also combine with lanthanum into an eutectic. The eutectic is easy to wet the tungsten matrix and migrate over its surface to form a thin emission film. As a result, the cathode emission is greatly increased. In addition, the La-Wc cathode has capability to resist poisoning of oil vapour is for the reason that the carbon from the oil vapour reacts with the lanthanum in the eutectie and forms La2C3, which is also a good emissive material.