The porous tungsten matrixes of barium tungsten cathodes are prepared by spark plasma sintering (SPS). By adjusting the raw powder particle diameter and the porosity, the matrixes with different average distances between the pores are obtained. The microstructure and the emission performance of the barium tungsten cathode are analyzed using scanning electron microscopy (SEM), electron emission measurement system, and X-ray photoelectron spectroscopy (XPS). The average distances between the pores of three cathodes are 5.08, 5.74, and $6.91\,\mu \text{m}$ , respectively. The cathode with a distance of $5.74\,\,\mu \text{m}$ has the best zero-field current density and the lowest work function. With the increase in the pulsewidth, the variation rate of the current density for the 5.74- $\mu \text{m}$ cathode is the smallest, indicating the emission stability is the best. The best emission performance can be ascribed to the formation of the optimal Ba–O dipoles’ coverage on the cathode surface.

中文翻译：

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表面钨分布对钡钨阴极发射性能的影响

钡钨阴极的多孔钨基体是通过放电等离子烧结（SPS）制备的。通过调整原粉粒径和孔隙率，得到不同平均孔距的基体。使用扫描电子显微镜（SEM）、电子发射测量系统和X射线光电子能谱（XPS）分析了钡钨阴极的微观结构和发射性能。三个阴极孔之间的平均距离分别为 5.08、5.74 和 $6.91\,\mu \text{m}$ ， 分别。阴极距离为 $5.74\,\,\mu \text{m}$ 具有最佳的零场电流密度和最低的功函数。随着脉宽的增加，电流密度的变化率为 5.74- $\mu \text{m}$ 阴极最小，表明发射稳定性最好。最佳发射性能可归因于在阴极表面形成最佳 Ba-O 偶极子覆盖。