Oxide-Cored Cathode

We invented the oxide-cored cathode. It is a fine platinum wire having an oxide-core. A thin platinum rod is bored along the axis, the empty core made by boring is filled with oxide powder and then the rod is drawn through a series of dies, forming a wire. For example, the diameter of the wire is 0.3 mm and that of the core 0.03 mm. The wire is cut into short pieces and when heated, the cross-section of the piece becomes an electron source. The oxide-cored cathode was tested in conventional electron microscopes and was found to emit electrons from the cross-section of the core only and that generally, it is more durable than pure tungsten cathode.