Introduction to Gas Ionization
The gas is subjected to electric field or thermal energy, which will make the electrons in the neutral gas atoms gain enough energy to overcome the gravity of the nucleus and become self-electrons. The electrons become positively charged positive ions. This process of making neutral gas molecules or atoms release electrons to form positive ions is called gas ionization.
In general, the gas is non-conductive. For example, the charged body supported by an insulating frame placed in the air, the charge disappears very slowly; pull the knife switch on the circuit, the circuit interrupts the current, these all indicate that the air is not conductive. The gas is able to conduct electricity because it ionizes under certain applied conditions. So it becomes a conductor.