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.
In vacuum tubes and gas-filled tubes, a hot cathode or thermionic cathode is a cathode electrode which is heated to make it emit electrons due to thermionic emission. This is in contrast to a cold cathode, which does not have a heating element. The heating element is usually an electrical filament heated by a separate electric current passing through it. Hot cathodes typically achieve much higher power density than cold cathodes, emitting significantly more electrons from the same surface area. Cold cathodes rely on field electron emission or secondary electron emission from positive ion bombardment, and do not require heating. 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. Today, hot cathodes are used as the source of electrons in fluorescent lamps, vacuum tubes, and the electron guns used in cathode ray tubes and laboratory equipment such as electron microscopes.
In vacuum tubes and gas-filled tubes, a hotcathode or thermionic cathode is a cathode electrode which is heated to make it emit electrons due to thermionic...
A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic...
tube. The other type of cathode is a hotcathode, which is heated by electric current passing through a filament. A cold cathode does not necessarily operate...
10−8 - 10−1 Pa) Most ion gauges come in two types: hotcathode and cold cathode. In the hotcathode version, an electrically heated filament produces an...
Cathode rays or electron beams (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes...
but the hot water can itself be utilized. Furthermore, transferred DC torches can be used in a twin-torch setup, where one torch is cathodic and the other...
or thermionic valve utilizes thermionic emission of electrons from a hotcathode for fundamental electronic functions such as signal amplification and...
as hotcathodes. However, cold cathode tubes have cathodes that emit electrons only due to the large voltage between the electrodes. The cathodes will...
electrostatic thermionic electron gun is formed from several parts: a hotcathode, which is heated to create a stream of electrons via thermionic emission;...
Electron versus electron hole Electron microscope Tafel equation Hotcathode Cold cathode Reversible charge injection limit Wikimedia Commons has media related...
with a "cold cathode" generating an electron beam by a corona discharge tube, the other one produces a beam using a "hotcathode". Cold-cathode CL microscopes...
thermionic emission is that of electrons from a hotcathode into a vacuum in a vacuum tube. The hotcathode can be a metal filament, a coated metal filament...
used in ultrahigh vacuum. They come in two types: hotcathode and cold cathode. In the hotcathode version an electrically heated filament produces an...
Cathodic protection (CP; /kæˈθɒdɪk/ ) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell...
English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were discovered. Developed from the earlier...
implementations but all are essentially triode devices. All triodes have a hotcathode electrode heated by a filament, which releases electrons, and a flat...
One common noise source was a thermally-limited (saturated-emission) hot-cathode vacuum tube diode. These sources could serve as white noise generators...
thyratron. A thyratron consists of a hotcathode, an anode, and one or more control grids between the anode and cathode in an airtight glass or ceramic envelope...
In thermionic electron guns, the work function and temperature of the hotcathode are critical parameters in determining the amount of current that can...
Lanthanum oxide and the boride are used in electronic vacuum tubes as hotcathode materials with strong emissivity of electrons. Crystals of LaB 6 are...
from the propellant gas's atoms. These electrons can be provided by a hotcathode filament and accelerated through the potential difference towards an...
A Nixie tube (English: /ˈnɪk.siː/ NIK-see), or cold cathode display, is an electronic device used for displaying numerals or other information using glow...
Bertrand Johnson implemented the hotcathode to drastically reduce the voltage requirements for the device. The Cathode Ray Oscillograph was subsequently...
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