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A hot cathode is a cathode that is heated by a filament to produce electrons by thermionic emission. [5] [9] The filament is a thin wire of a refractory metal like tungsten heated red-hot by an electric current passing through it. Before the advent of transistors in the 1960s, virtually all electronic equipment used hot-cathode vacuum tubes.
There are two types of hot cathode. In a directly heated cathode, the filament is the cathode and emits the electrons. In an indirectly heated cathode, the filament or heater heats a separate metal cathode electrode which emits the electrons. From the 1920s to the 1960s, a wide variety of electronic devices used hot-cathode vacuum tubes.
Electron flow is the reverse of conventional current ... A common variant of a diode is a light-emitting diode, ... the element names are: plate, cathode, and heater.
Secondary electron emission is used in photomultiplier tubes and image intensifier tubes to amplify the small number of photoelectrons produced by photoemission, making the tube more sensitive. It also occurs as an undesirable side effect in electronic vacuum tubes when electrons from the cathode strike the anode, and can cause parasitic ...
An electron gun (also called electron emitter) is an electrical component in some vacuum tubes that produces a narrow, collimated electron beam that has a precise kinetic energy. The largest use is in cathode-ray tubes (CRTs), used in older television sets , computer displays and oscilloscopes , before the advent of flat-panel displays .
The electron gun contains a heater, which heats a cathode, which generates electrons that, using grids, are focused and ultimately accelerated into the screen of the CRT. The acceleration occurs in conjunction with the inner aluminum or aquadag coating of the CRT. The electron gun is positioned so that it aims at the center of the screen. [188]
FED display operates like a conventional cathode-ray tube (CRT) with an electron gun that uses high voltage (10 kV) to accelerate electrons, which in turn excite the phosphors, but instead of a single electron gun, an FED display contains a grid of individual nanoscopic electron guns. It consists of 2 sheets of glass spaced at regular intervals ...
The hollow cathode effect was recognized by Friedrich Paschen in 1916. [2] In a hollow cathode, the electron emitting surface is in the inside of the tube. Several processes contribute to enhanced performance of a hollow cathode: The pendulum effect, where an electron oscillates back and forth in the tube, creating secondary electrons along the way