Thermionic emission is the flow of charge carriers from a surface or over some other kind of electrical potential barrier, caused by thermal vibrational energy overcoming the electrostatic forces restraining the charge carriers. The charge carriers can be electrons or ions, and are sometimes referred to as "thermions". The total charge of the emitted carriers (either positive or negative) will be equal in magnitude and opposite in sign to the charge left in the emitting region. The most classic… (More on Thermionic)