对镧-碳化钨阴极发射大和抗油蒸汽中毒的探讨
STUDY ON EMISSION PROPERTIES OF La-WC CATHODE AND ITS RESISTANCE TO POISONING OF OIL VAPOUR
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摘要: 本文提出了解释镧-碳化钨(La-WC)阴极发射大和抗油蒸汽中毒能力强的一些设想,并通过实验,验证了所提出的设想。在La-WC阴极的工作温度范围内,La和 WC发生化学反应,生成La2C3。La2C3也是一种良好的发射材料,它具有与镧相近的逸出功。La2C3能与镧形成共熔体,对钨基底浸润良好,易形成较好的发射层,而使发射显著增大。La-WC阴极抗油蒸汽中毒是由于污染的碳与共熔体中的镧形成La2C3,而La2C3也是良好的发射物质的缘故。
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Abstract: 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. -
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