Tungsten filament is arguably the key component of the incandescent lamp business.

The tungsten filament of a vacuum incandescent lamp is heated to temperatures where visible light is emitted by resistance heating. The filament acts as an electrical resistor, which dissipates power proportional to the voltage applied, times the current through the filament. When that power level is sufficient to raise the temperature to above 1000 degrees Kelvin, visible light is produced.

The tungsten Filament is quite sturdy and provides stable and uniform electron emission, primarily used in scanning electron microscopy.

Custom tungsten filament cathodes in a variety of filament sizes and configurations and a variety of glass or ceramic bases are available. Some combinations of various options may not be possible due to design considerations. All tungsten cathodes are shipped pre-fired, vacuum clean, and ready to install.