EB Tungsten Filament and Cathode

Generally speaking, The EB（electron beam） tungsten filament consists of a cathode focusing electrode, and an anode. As a term of the electrochemical reaction, the cathode of EB tungsten filament refers to obtain electrons pole which can produce the reduction reactions. The cathode is an important part of the EB tungsten filament, which determines the ability of emitting and the life length of electron beam.

Nowadays, the most widely recognized of the form of the cathode is the directly heated cathode indirectly heated cathode, the latter can be divided into bombardment type and heating type. Bombardment-type offers hundreds or even thousands VA（volt-ampere） to the EB tungsten filament, when the cathode is heated to a certain temperature and then it will produce a large number of electrons. For heating type, when EB tungsten filament burned the cathode by electric current flowing. If the cathode reaches the temperature, then it can produce the electrons.

The temperature of EB tungsten filament has a strong influence on the intensity of the electron emission. Under the same emission intensity conditions, if the recovery percent of cathode material is small, then the temperature of the EB tungsten filament can be greatly reduce. It benefits to protect the EB tungsten filament. If users want to lengthen the life of the EB tungsten filament, people should choose cathode materials with a higher melting point and a smaller evaporation rate.

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