A cold cathode refers to a type of cathode that is not heated, and is often used in fluorescent and gas-based lighting systems, such as neon tubes. While these cathodes do not produce as much heat as incandescent cathodes, they can still become hot during use. While cold cathode lights have been used widely in modern lighting systems, they typically have higher power consumption than alternative lighting systems.
Cold cathodes differ from hot cathodes, which are heated to emit electrons. Discharge tubes with incandescent cathodes have a sheath filled with a low-pressure gas that contains two electrodes. Ordinary vacuum tubes, fluorescent lamps, high-pressure discharge lamps, and vacuum fluorescent displays are examples of devices with incandescent cathodes.
A cold cathode uses an electric field to maintain its current flow, instead of heating to charge its energy flow. The cathode can emit secondary electrons at a ratio greater than one, which can cause a breakdown. When an electron leaves the cathode, it collides with neutral gas molecules. This collision can excite the molecule, releasing an electron and producing a positive ion. If enough positive ions hit the cathode to release an average of one more electron for each electron leaving the cathode, then the discharge is self-sustaining. External circuits limit the discharge current.
FAQs
What are some examples of lighting systems that use cold cathodes?
Cold cathodes are commonly used in different forms of fluorescent lighting and gas-based lighting systems, such as neon tubes. Additionally, cold cathode lights have been used in modern lighting systems, although they may have higher power consumption than alternative lighting systems.
How is a cold cathode different from a hot cathode?
A cold cathode differs from a hot cathode because it is not heated. While a cold cathode uses an electric field to maintain its current flow, a hot cathode is heated to cause thermionic emission of electrons. Devices that use hot cathodes include fluorescent lamps, vacuum fluorescent displays, vacuum tubes, and high-pressure discharge lamps.
Why are cold cathode lights used in lighting systems?
Cold cathode lights are used in different forms of fluorescent lighting and gas-based lighting systems, such as neon tubes. Although cold cathode lights have higher power consumption than alternative lighting systems, they have been commonly used in modern lighting systems.
Conclusion
In summary, a cold cathode is a type of cathode that is not heated and is often used in fluorescent and gas-based lighting systems. Unlike the hot cathode, which is heated to emit electrons, a cold cathode uses an electric field to maintain its current flow. While cold cathode lights have been widely used in modern lighting systems, they may have higher power consumption than alternative lighting systems.
