Many properties of cathodic arcs from single-element cathodes show a correlation to the cohesive energy of the cathode material. For example, the burning voltage, the erosion rate, or, to a lesser extent, plasma properties like electron temperatures or average ion energy and charge states. For multi-element cathodes, various phases with different cohesive energies can initially be present in the cathode, or form due to arc exposure, complicating the evaluation of such correlations. To test the influence of morphology and phase composition of multi-element cathodes on cathodic arc properties, a Nb-Al cathode model system was used that includes: pure Nb and Al cathodes; intermetallic Nb3Al, Nb2Al and NbAl3 cathodes; and 3 composite Nb-Al cathodes with atomic ratios corresponding to the stoichiometric ratios of the intermetallic phases. Pulsed cathodic arc plasmas from these cathodes were examined using a mass-per-charge and energy-per-charge analyzer, showing that charge-state-resolved ion energy distributions of plasmas from the intermetallic and corresponding composite cathodes are nearly identical. An examination of converted layers of eroded cathodes using x-ray diffraction and scanning electron microscopy indicates the formation of a surface layer with similar phase composition for intermetallic and their corresponding composite cathode types. The average arc voltages do not follow the trend of cohesive energies of Nb, Al and intermetallic Nb-Al phases, which have been calculated using density functional theory. Possible reasons for this effect are discussed based on the current knowledge of multi-element arc cathodes and their arc plasma available in literature.

中文翻译：

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Nb-Al 阴极的侵蚀和阴极电弧等离子体：复合材料与金属间化合物

来自单一元素阴极的阴极电弧的许多特性显示出与阴极材料的内聚能相关。例如，燃烧电压、腐蚀速率，或者在较小程度上，等离子体特性，如电子温度或平均离子能量和电荷状态。对于多元素阴极，具有不同内聚能的各种相最初可能存在于阴极中，或者由于电弧暴露而形成，使这种相关性的评估变得复杂。为了测试多元阴极的形貌和相组成对阴极电弧特性的影响，使用了 Nb-Al 阴极模型系统，包括：纯 Nb 和 Al 阴极；金属间化合物 Nb3Al、Nb2Al 和 NbAl3 阴极；和 3 个复合 Nb-Al 阴极，其原子比对应于金属间相的化学计量比。使用每电荷质量和每电荷能量分析仪检查来自这些阴极的脉冲阴极电弧等离子体，表明来自金属间化合物阴极和相应复合阴极的等离子体的电荷态分辨离子能量分布几乎相同。使用 X 射线衍射和扫描电子显微镜检查腐蚀阴极的转化层表明，对于金属间化合物及其相应的复合阴极类型，形成了具有相似相组成的表面层。平均电弧电压不遵循使用密度泛函理论计算的 Nb、Al 和金属间 Nb-Al 相的内聚能趋势。根据文献中现有的多元素电弧阴极及其电弧等离子体的知识，讨论了这种效应的可能原因。