Instructables

Electron gun

How can we build a heater for electron gun?
can we use tungsten filament of lamp for heater ?
please tell me how to build heater?????????????????????????????? thank very much

I guessing  that would work.  The actual amount of emission current you can get depends mostly on the temperature of the filament, and the work function of the metal the filament is made of.

Also you have to do something to the atmosphere surrounding the filament,  to keep the filament from burning.  The gasses surrounding the filament have to be inert, or vacuum, or something like that.

BTW, if you can find an old CRT type television or computer monitor, those come with an electron gun, and focusing electrodes, and vacuum, and a phosphor screen, already built in.

The Wikipedia page on thermionic emission has the formulas explaining how the heated filament gives free electrons
http://en.wikipedia.org/wiki/Thermionic_emission

Also
http://en.wikipedia.org/wiki/Electron_gun
Thoriated tungsten