What is Impact Ionization?

There is always a certain amount of electrons and ions in the air, which arise under the influence of cosmic radiation penetrating into the earth’s atmosphere. In a rarefied gas, electrons collide with atoms less often. Therefore, during the time between collisions under the action of an electric field, the speed of electrons increases. They acquire kinetic energy sufficient to knock another electron out of it when colliding with an electrically neutral atom (or molecule). This produces a positive ion.