In vacuum tubes, a hot cathode is a cathode electrode which emits electrons due to thermionic emission. In the accelerator physics (particle accelerator) community, these are referred to as thermionic cathodes. The heating element is usually an electrical filament. 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.
Hot cathodes are the main source of electrons in electron guns in cathode ray tubes, electron microscopes, vacuum tubes, and fluorescent lamps.
Read more about Hot Cathode: Principles, Cathode Heater, Failure Modes, Transmitting Tube Hot Cathode Characteristics
Famous quotes containing the word hot:
“Away went the messenger’s bicycle,
His serpent’s track went up the hill forever.
And all the time she stood there hot as fever
And cold as any icicle.”
—John Crowe Ransom (1888–1974)