The physical plasma is a mixture of charged components, electrons and ions. This means that a plasma contains free charge carriers (radicals). Since the plasma state can be created from the gaseous state of aggregation by adding further energy, it is often referred to as the fourth state of aggregation. If sufficient energy is added to a gas, the atomic shells break open and electrons are released. The electrons are accelerated and break more atomic shells.
The positive ions of the gas are highly reactive and immediately try to fill the bond released by the electron. During sterilisation, this effect can be used because reactions with microorganisms also take place.