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Closeup of the filament in a low pressure mercury gas-discharge lamp showing white thermionic emission mix coating on the central portion of the coil.
Closeup of the filament in a low pressure mercury gas-discharge lamp showing white thermionic emission mix coating on the central portion of the coil. Typically made of a mixture of barium, strontium and calcium oxides, the coating is sputtered away through normal use, eventually resulting in lamp failure.
One of the bulbs with which Edison discovered thermionic emission. It consists of an evacuated glass light bulb containing a carbon filament (hairpin
One of the bulbs with which Edison discovered thermionic emission. It consists of an evacuated glass light bulb containing a carbon filament (hairpin shape), with an additional metal plate attached to wires emerging from the base. Electrons released by the filament were attracted to the plate when it had a positive voltage.
Schottky-emitter electron source of an electron microscope
Schottky-emitter electron source of an electron microscope
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A tungsten filament acting as a directly heated cathode in a low pressure mercury gas discharge lamp which emits electrons. To increase electron emiss
A tungsten filament acting as a directly heated cathode in a low pressure mercury gas discharge lamp which emits electrons. To increase electron emission, a white thermionic emission mix coating is applied on hot cathodes, visible on the central portion of the coil. Typically made of a mixture of barium, strontium, and calcium oxides, the coating is sputtered away through normal use, eventually resulting in lamp failure.
Two indirectly heated cathodes (orange heater strip) in ECC83 dual triode tube
Two indirectly heated cathodes (orange heater strip) in ECC83 dual triode tube
Glow of a directly heated cathode in an Eimac 4-1000A 1 kW power tetrode tube in a radio transmitter. Directly heated cathodes operate at higher tempe
Glow of a directly heated cathode in an Eimac 4-1000A 1 kW power tetrode tube in a radio transmitter. Directly heated cathodes operate at higher temperatures and produce a brighter glow. The cathode is behind the other tube elements and not directly visible.
SEM Image of G1 Support and G1 Wire, of a heavily used Pentode showing Barium oxide Contamination (green) from the cathode.
SEM Image of G1 Support and G1 Wire, of a heavily used Pentode showing Barium oxide Contamination (green) from the cathode.