Barium Tungsten Cathode Electron Microscopy Analysis

With the development of microwave technology, Ba-W cathode is widely applied for high-power microwave vacuum electronical parts of an apparatus which ask for big electricity density and high stability, and is thought much of by scholar. For improving the capability, scholars research the emissive capability of cathode from theory, fill, arts and crafts, material and so on. In the process of actual production, factors that affects the cathode emissive cathodes are numerous, example for microstructure, composition, pollution and so on, but systemic research about that aspect is small.Ba-W cathode materials produced by certain state factory which adopt dipping arts and crafts join Aluminate or Sc203 into hole of W sponge, tectorial cathode Magnetron Sputtering metal film or alloy film in the basic of above arts and crafts, which improve cathode emissive capability. But there are phenomena that emissive capability decline or emissive electricity is not stable in the process of using. According to the things, it is the center in which cathode microstructure affects the capability and we carry through such series analysis research from the point of view of microstructure that affects the work condition, jointing quality, tectorial quality, thickness and uniformity of cathode capability with diversified modern microcosmic analysis means.The main results are as follows:1.Cathode require high emissive electricity density, good stable capability, long using life and rigor work condition as the core of electricity and vacuum parts of an apparatus. Aiming at the phenomena that emissive electricity decline in the process of work,the microstructure change and form cause of the crazing,cathode surface pollution and deposit of sponge hole are studied with SEM and EDS, and the result indicates that work temperature of cathode, circumstance atmosphere and surface cleaning are the main cause that form above typical microstructure. The way of cathode invalidation is put up. Cathode sleeve jointing bug is studied, the gap that affects the jointing quality and sleeve heat exchange is analized.2.The arts and crafts process and film-form mechanism are introduced, the microstructure and composition of different film in the surface of Ba-W cathode are studied. The microstructure of film of Os and Ir and alloy film of Os-Ir-Al and Os-Re and the microstructure change after the 1200℃aging are researched, the result indicates that the micro-image change of cathode surface of Os-Ir-Al is the least, but the grain is big, and then the single film of Os or Os-Re, the most change is the film of Ir.The film is token of micro-composition, through selecting incidence voltage and different character spectrum of the same element, it can void the second explode that underlay element bring X radial to surface film, and the exact surface analysis result can be gained.3.The analysis and test technology that electricity probe lossless measures the thickness of Ba-W cathode film are studied. According to the connection between electron beam action depth that reach to the surface of film and incidence voltage, it can calculate and simulate the tectorial thickness of cathode. Through the connection between accelerate voltage and character X radial of WL and film Ir, the incidence voltage can be got when X radial intensity of W underlay is zero or X radial intensity of film is one. Fixing the incidence voltage Ed, through changing suppose film thickness and making X radial of W underlay zero or X radial intensity of film one , it can lossless measure the thickness of film ,and the operation is convenience with MonteCarlo simulation.