The principal use of lanthanum hexaboride is in hot cathodes, either as a single crystal or as a coating deposited by physical vapor deposition.
22.
As described in July 1941, the Beckman spectrophotomter could use a " hot cathode hydrogen discharge tube " or a tungsten light source interchangeably.
23.
The hot cathode can be a metal filament, a coated metal filament, or a separate structure of metal or carbides or borides of transition metals.
24.
These cold cathode type X-ray tubes were used until about 1920, when they were superseded by the hot cathode Coolidge X-ray tube.
25.
A hot cathode is at an advantage, as ionization of the gas is made easier; thus, the tube's control electrode is more sensitive.
26.
Electrical filaments are also used in hot cathodes of fluorescent lamps and vacuum tubes as a source of electrons or in vacuum tubes to heat an electron-emitting electrode.
27.
A duoplasmatron is a type of glow discharge ion source that consists of a hot cathode or cold cathode that produces a plasma that is used to ionize a gas.
28.
Today, hot cathodes are used as the source of electrons in fluorescent lamps, vacuum tubes, and electron guns in cathode ray tubes and laboratory equipment such as electron microscopes.
29.
X-rays can be generated by an X-ray tube, a vacuum tube that uses a high voltage to accelerate the electrons released by a hot cathode to a high velocity.
30.
In vacuum tubes, a "'hot cathode "'or "'thermionic cathode "'is a cathode electrode which is heated to make it emit electrons due to thermionic emission.
