Chemical Vapor Deposition of Oriented Tungsten Foils for Thermionic Cathodes

摘要

Efforts under the present contract were devoted to the preparation of CVD tungsten emitters containing a variety of preferred crystallographic orientations. The work is divided into two phases. In Phase I, a CVD tungsten deposition apparatus was built and CVD tungsten samples of various preferred crystallographic orientations were prepared and characterized with respect to microstructures and nature and degree of preferred orientations. These samples were delivered to NRL for the evaluation of their electron emission properties. In Phase II, efforts were made to produce a high degree of preferred crystallographic orientations in thin CVD tungsten deposits (approx. 25 micron thickness) which are amenable to hole drilling by laser. Techniques for preparing CVD tungsten cathode structure were established and samples of oriented tungsten cathode structure were prepared for NRL evaluation.