Noun
Townsend discharge (plural Townsend discharges)
A gas ionization process where free electrons, accelerated by a sufficiently strong electric field, give rise to electrical conduction through a gas by avalanche multiplication caused by the ionization of molecules by ion impact.
The ionization is considerably amplified within the tube by the Townsend discharge effect to produce an easily measured detection pulse, which is fed to the processing and display electronics. Source: Internet
The Townsend discharge is a good example of the creation of positive ions and free electrons due to ion impact. Source: Internet