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What Is a Plasma Cathode?

Some modern televisions use plasma cathodes instead of traditional hot cathodes.
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  • Written By: Jean Marie Asta
  • Edited By: Jessica Seminara
  • Last Modified Date: 20 December 2014
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A plasma cathode is a device that creates light within a cathode tube using plasma. An ionized gas, plasma is the most plentiful kind of matter that we know of. It can be found on earth, but its most visible form is that of the earth’s sun. Plasma can be created in industrial and laboratory settings as well.

Newer computer monitors and television sets commonly make use of a plasma cathode. These devices can also be used to create light and certain kinds of beams needed for scientific research. In order to function, electrical energy is sent through a field of plasma in a vacuum tube. This tube is the plasma cathode.

There are many other types of cathodes used today in different environments. Many of them use plasma to function. Cold cathodes are commonly used in many settings as they do not require extra heat to function and produce little heat on their own. They are a popular form of conventional lighting as well because they are brighter and require less energy than neon or fluorescent lighting. Cold cathodes are also used to backlight LCD displays in computer monitors, television sets, and hand-held electronic devices.

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Hot cathodes are a form of plasma cathode used for lighting applications as well, but these produce some heat when they are used. Early forms required applying direct heat to certain elements and compounds in a vacuum. These kinds are no longer used, but fluorescent lighting is a hot cathode that is still in common use. They do not produce much heat, but give off a noticeable sound. Hot cathodes are also essential in the creation of electron guns, which are commonly used in laboratories and also are the main component of tube-style television sets.

The electron guns used in television sets and other digital visual devices are also known as cathode rays. These devices are forms of plasma cathodes that manipulate a series of small dots on a screen very quickly. The dots are fired from an electron gun and create the illusion of a moving picture.

Although the cathode ray form of display screens is no longer as prevalent as it once was, newer versions still use plasma cathode technology. Cold cathode lighting is increasingly used as it requires little energy. This type of plasma cathode also doesn’t produce heat that can be damaging to devices or affect the outcome of certain kinds of research.

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