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阴极中毒是因发射表面上吸附气体层之故。吸附气体的量与吸附热、气体压强以及阴极温度有关。吸附的气体在阴极表面上形成带电偶极子,它导致逸出功增加,从而引起发射下降或阴极中毒。因为偶极矩大小和吸附气体的量非定量所知,所以通过实驗測量阴极中毒。本文叙述使用的实驗裝置和实驗方法。介紹的实驗結果包括鎢阴极、六硼化鑭阴极和浸漬镧的碳化鎢阴极受氧的中毒。六硼化鑭阴极的抗氧中毒的能力强于鎢或浸漬鑭的磺化鎢阴极。还测量了六硼化鑭阴极受氮、二氧化碳、空气、氬和氫等气体的中毒特性。测得的鎢阴极、六硼化鑭阴极和浸漬鑭的磺化鎢阴极受氧中毒的特性,与其他不同类型阴极受氧中毒的数据作了比較。这就为选择使用在中毒环境下的阴极提供定量基础。
Cathodic poisoning is due to the surface layer of adsorbed gas on the surface so. The amount of adsorbed gas depends on the heat of adsorption, the pressure of the gas, and the temperature of the cathode. Adsorbed gas forms a charged dipole on the cathode surface, which causes an increase in work function, resulting in decreased emission or cathodic poisoning. Because of the magnitude of the dipole moment and the amount of adsorbed gas, which is not known, cathode poisoning is measured experimentally. This article describes the experimental setups and experimental methods used. The experimental results presented include the poisoning of tungsten cathodes, lanthanum hexaboride cathodes and lanthanum-doped tungsten carbide cathodes by oxygen. The ability of the lanthanum hexaboride cathode to resist oxygen poisoning is stronger than that of tungsten or a lanthanum-doped sulfonated tungsten cathode. Also measured lanthanum hexaboride cathode by nitrogen, carbon dioxide, air, argon and hydrogen gas poisoning characteristics. The measured oxygen toxicity characteristics of tungsten cathodes, lanthanum hexaboride cathodes and lanthanum sulphonated tungsten cathodes were compared with those of other different types of cathode oxygen toxicity. This provides a quantitative basis for choosing to use cathodes in toxic environments.