Relaxation of the volume charge created by the electron flow in the air

Thermalization of high-energy electrons in the air is considered. It was shown that the formation of a volume charge in the gas during this process is due to the formation of negative oxygen ions. The characteristic times of formation and destruction of ions are considered. A mathematical model of the volume charge relaxation based on an estimate of the ion drift velocity in an electric field is constructed. A condition is obtained under which the drift of ions in an electric field prevails over the gas-dynamic expansion of the ionized substance as a whole.