Molybdenum foil for mesh
High power travelling-wave tube is characterized by high power, high efficiency, wide band and miniaturization. It is widely used in electronic countermeasures, electronic warfare, ground radar, satellite communication, meteorological observation and space measurement, and plays a very key role. It is known as the "heart" of electronic system. With the increase of the power requirement of the TWT, simply applying the modulating voltage to the anode or focusing pole cannot meet the requirement of high current control.
In modern microwave vacuum devices, the cathode current is controlled by grid modulation. The grid-controlled pulsed traveling wave tube uses a grid-controlled electron gun, that is, a control grid is added in front of the cathode, and a shadow grid is added between the control grid and the cathode, so as to achieve the purpose of controlling the large injection current with low modulation voltage and power when the pulse is used. Therefore, the grid is one of the key components of traveling wave tube and plays a very important role in realizing the electrical performance of traveling wave tube. Once the grid wire is stratified, cracked or even broken, it will lead to the abandonment of the whole tube.
Because the grid is close to the hot cathode and the working temperature is abnormally high, the grid is usually made of molybdenum strip material with good high temperature strength and large escape power through stamping/hydraulic molding and electric discharge machining. But when the grid is pressed/hydraulic crown, the edge part is pressed and fixed without deformation, and the forming of the crown is completed only by the plastic deformation of the central part. If the crown is high and the forming deformation is large, the molybdenum foil is prone to delamination, cracking and even fracture in the process of processing, resulting in the yield of one molding is often lower than 10%. Considering the harsh requirements of processing technology and operating environment, the ideal molybdenum foil for grid mesh must have the characteristics of high dimensional accuracy, reasonable matching of strength and toughness, good stamping performance, so it is very important to develop the preparation technology and method of high performance molybdenum foil for grid controlled pulse traveling wave tube grid.
