Authors : A.I. Gaidar, G.G. Bondarenko, I.P. L and N.V. Kashirina
Abstract: The universal parameter that characterizes the emission capacity of a cathode material is its electron work function which has a definitive impact on the emission current. Reducing the work function is a top-priority task for the designers of all types of cathode materials. The emission properties of composite cathode materials are determined primarily by the properties of their work surface. The investigation of the connection between the structure and physical and chemical properties of the cathode surface and its emission properties is a relevant problem. The understanding of these properties not only gives a mode in-depth perception of the physics behind the processes that occur on the surface of the cathode but also enables purposefully adjusting its properties by reasonably choosing the parameters of the primary components and improving the cathode manufacturing technology. An important parameter of the composite material is the emission homogeneity of its surface which is determined primarily by the homogeneous distribution of the emission active phase and the chemical and structural homogeneity of the work surface of the cathode. This research used methods of scanning electron microscopy and electron probe microanalysis to study the effect of the grain-size composition of primary powder components of a pressed Pd-Ba cathode on the evenness and density of distribution of powder particles of the emission active phase Pd5Ba on its surface. The optimal 5 particle size distribution of powder components was determined. An experimental technique for manufacturing pressed Pd-Ba cathodes was proposed, it enables increasing the evenness of the distribution of the emission active phase across the surface of the cathode. The increase in emission homogeneity reduced the work function of the electron from 2.5-2.4 eV which resulted in a more than 2.5 fold increase in emission current density.
A.I. Gaidar, G.G. Bondarenko, I.P. L and N.V. Kashirina, 2017. Emission Characteristics of Pressed Pd-Ba Cathodes with an Increased Homogeneity of Distribution of the Emission Active Phase on the Surface. Journal of Engineering and Applied Sciences, 12: 9075-9081.