Electrons are the subatomic particles that are carrying a negative charge. It has a mass equals to 1/1836 that of proton. A thermo electron is nothing but the electron that gets emitted using thermal activities.
Thermionic emission:The flow of energy carriers over potential energy barrier after they got induced by heat is known as the thermionic emission. This happens when the thermal energy inputted rises above the restraining force of the electrons.A very good example for the thermionic emission is the Edison effect in which the electrons are emitted from the heated cathode of metal into the vacuum while inside a vacuum tube.
The thermionic emission literally means the emission of charges due to the thermal action. After the electrons are emitted the area around the actual location of emission will be having a charge that is exactly equivalent but opposite in sign to the number of electrons that got emitted.The emission of electrons was first discovers by J J Thompson in 1897. Till that year the electron was not distinguished as a physical particle or the scientists had not used such a terms either.
Thermionic emissionTwo Theories Related to Emission of ElectronsThere are two theories that define the emission of electrons due to thermal action. They are theRichardson’s law andSchottky effect.Richardson's Law, Schottky EffectAccording to the Richardson’s law, there is emission of one or more electrons from a solid metal that forms a ‘sea of electrons’. The electrons that are emitted will follow a statistical distribution and their velocities will be the same.
It is also defined that the minimum energy required for a electron to leave a particular surface is known to as a work function. By increasing or decreasing the work function, the thermionic action can be controlled.According to Schottky effect (also seen as Schottky emission), there are electron guns that can emit electrons. The emitter field will be biased into a negative sign in contrast to its surroundings which leads to create a electric field in the surroundings. This surface barrier will get lowered by this electric field and there will be a rapid increase in the emission current.