"Most fluorescent lamps use electrodes that operate by thermionic emission, meaning they are operated at a high enough temperature for the electrode material (usually aided by a special coating) to emit electrons into the tube by heat."
Thermionic emission is how vacuum tubes work, like the 12AX7's and 6L6's or whatnot in your guitar amp.
A fluorescent lamp also qualifies as a vacuum tube:
http://en.wikipedia.org/wiki/Fluorescent_lamp#Principles_of_...
http://en.wikipedia.org/wiki/Fluorescent_lamp#Cold_cathode_l...
"Most fluorescent lamps use electrodes that operate by thermionic emission, meaning they are operated at a high enough temperature for the electrode material (usually aided by a special coating) to emit electrons into the tube by heat."
Thermionic emission is how vacuum tubes work, like the 12AX7's and 6L6's or whatnot in your guitar amp.