Barium Tungsten Cathode
As the electron emission source of vacuum electronic devices, the cathode is a core component of microwave tubes, and its performance directly affects the device's performance and lifespan, hence it is dubbed the "heart" of vacuum electronic devices. Barium tungsten cathode is an excellent type of hot cathode, composed of a porous tungsten substrate filled with electron-emitting material. It features low work function, good stability, high emission current, high emission efficiency, and resistance to ion bombardment.
Principle Structure:
The principle structure of the barium tungsten cathode is illustrated in the diagram below. It inherits the advantages of the L-cathode, having a metallic framework (tungsten sponge) with a sufficient reserve of active material. However, it addresses the drawbacks of the L-cathode with two major improvements: 1) eliminating the separate storage chamber and directly storing the active material in the pores of the tungsten sponge; 2) using barium-resistant salts (such as aluminate, tungstate, and scandate) instead of carbonates as the active material, solving the issue of long evacuation time of the L-cathode.
Preparation Process:
The preparation process of barium tungsten cathode includes two methods: impregnation and compression. In the impregnation method, the tungsten sponge is first produced, and then the melted active material is immersed into the sponge. Cathodes made by this method are called impregnated barium tungsten cathodes, or simply impregnated cathodes. In the compression method, the active material is uniformly mixed with tungsten powder, and then pressed into shape and sintered to form the cathode, which is called compacted barium-tungsten cathode or compressed cathode.
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Applications:
1.HID lamps (High-Intensity Discharge Lamps)
The low work function and high current density of barium tungsten cathodes enable HID lamps to emit bright and stable light, suitable for applications requiring high brightness and long-life light sources, such as road lighting and industrial lighting.
2.Electric vacuum and laser devices
The low emission function of barium tungsten cathodes makes them commonly used in electric vacuum and laser devices. For example, in electro-optical source products, the electron emission performance of barium tungsten cathodes can achieve a significant improvement in start-up performance and brightness.
3.Stage and hall effect displays
In theaters and halls, optoelectronic products are often used to create various atmospheres and effects. High-frequency strobe lights prepared with barium tungsten cathodes have very long service life and stable performance.
4.Film projection and recording
In the film industry, barium tungsten cathodes are widely used in projection and recording equipment. Their excellent performance ensures the stability and efficiency of film and video equipment during prolonged operation.
5.Laser mercury pumping
In laser technology, barium tungsten cathodes are also used as electrode materials for laser mercury pumping. Their high electron emission capability and low electrode operating temperature contribute to enhancing the performance and stability of lasers.
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