For low electrode wear the electrodes are usually made of tungsten, which has the highest melting point of any metal, to handle the thermionic emission of electrons.
32.
Although thermionic emission was originally reported in 1873 by Frederick Guthrie, it was Thomas Edison's apparently independent discovery of the phenomenon in 1883 that became well known.
33.
This does not mean the electrodes are cold ( indeed, they can be very hot ), but it does mean they are operating below their thermionic emission temperature.
34.
These unusual classes of compounds have allowed Dye to achieve work functions as low as 0 . 2 electronvolts _ low enough for thermionic emission at-80 degrees Celsius.
35.
The photomultiplier tube is an extremely sensitive detector of light, which uses the photoelectric effect and secondary emission, rather than thermionic emission, to generate and amplify electrical signals.
36.
Modern vacuum tubes use thermionic emission, in which the cathode is made of a thin wire filament which is heated by a separate electric current passing through it.
37.
As he continued to study filaments in vacuum and different gas environments, he began to study the emission of charged particles from hot filaments ( thermionic emission ).
38.
Phototubes and photomultipliers rely on electron flow through a vacuum, though in those cases electron emission from the cathode depends on energy from photons rather than thermionic emission.
39.
Furthermore, both lanthanum hexaboride and tungsten thermionic sources must be heated in order to achieve thermionic emission, this can be achieved by the use of a small resistive strip.
40.
A cathode made of a wire filament heated red hot by a separate current passing through it would release electrons into the tube by a process called thermionic emission.
