The Life Time of EB Tungsten Filament

The cathode of EB tungsten filament plays a fundamental role in the life length of EB tungsten filament, and the cathode’s material and temperature are the key factors. Therefore, when selecting the cathode material, a low work function material is the best choice.

There are two main factors to affect the life length of EB tungsten filament.

One is subjective reasons, heating emission requires a high temperature of the filament and the filament evaporation rate is proportional to the temperature index, the higher the temperature, the faster the evaporation rate of the filament. Therefore, under the condition of usage, user should try to ensure that the low temperature of EB tungsten filament, which is important for life length of the filament.

Another is objective reasons: the surface of EB tungsten filament is easy to form a tungsten oxide layer due to the leakage of vacuum, and the evaporation rate of the tungsten oxide is N times higher than that of the elemental tungsten. If there exists oxygen inside the bulb and under high temperature conditions, the reaction between EB tungsten filament and oxygen will blow the filament. As a result of it, the life length of EB tungsten filament will be significantly shortened. In addition, the moisture content of air has a certain influence on life length of the EB tungsten filament. Humidity will greatly reduce the life length of EB tungsten filament.

The life length of EB tungsten filament is limited. And the life length would change because of habits of the user. The EB tungsten filament requires a high vacuum environment and minimizes pollution, so the user should cultivate the habit of maintaining a vacuum system to prevent vacuum from leaking.

In short, although the quality of EB tungsten filament will influence its life length, users’ maintenance is more important, therefore, users should strengthen the management of the EB tungsten filament.

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