(北京工業(yè)大學(xué) 新型功能材料教育部重點實驗室， 北京 100022)
摘 要: 從理論上計算了碳化Mo-La2O3熱陰極材料在不同溫度下活性物質(zhì)鑭元素的蒸發(fā)速度，分析了鑭元素蒸發(fā)對材料熱電子發(fā)射及其穩(wěn)定性的影響。 計算結(jié)果表明： 當(dāng)溫度為1623~1700K時，陰極中鑭的擴(kuò)散速度大于陰極表面鑭的蒸發(fā)速度， Mo-La2O3陰極表面單質(zhì)La的生成和蒸發(fā)保持平衡， 陰極發(fā)射穩(wěn)定； 當(dāng)工作溫度超過1700K， 陰極表面鑭的蒸發(fā)速度超過擴(kuò)散速度，發(fā)射電流逐漸減少。 測試了Mo-La2O3陰極FU-6051電子管在不同溫度時的發(fā)射性能， 熱力學(xué)理論計算結(jié)果較好地解析了實驗結(jié)果。
關(guān)鍵字: Mo-La2O3熱陰極; 熱電子發(fā)射; 穩(wěn)定性; 蒸發(fā); 擴(kuò)散
ZHOU Mei-ling, ZUO Tie-yong
（The key Laboratory of Advanced Functional Materials,
Ministry of Education,
Beijing University of Technology, Beijing 100022, China）
Abstract: The evaporation rate of element La at different temperatures in carbonized Mo-La2O3 cathode were calculated according to thermodynamics theory. The results show that the diffusion rate is greater than the evaporation rate of La on cathode surface at the temperature range of 1623-1700K, so the formation and evaporation of La can remain balance and the emission current is stable, and that when the operating temperature is above 1700K, the evaporation rate of La exceeds its diffusion rate on the cathode surface so that the emission current decreases gradually. In addition, the emission properties of the FU-6051 tubes equipped with Mo-La2O3 cathodes were tested at different temperatures, and the experimental results confirme the thermodynamic calculation.
Key words: Mo-La2O3 heated cathode; thermionic electron emission; emitting stability; evaporation; diffusion
