The model accounts for all physical processes known Infrasonic DeuX play a role in the conversion of a streamer corona to a leader channel. Detailed discussion on the role of electron detachment in the development of the thermal-ionizational instability that triggers the spark development in short air gaps is presented. The dynamics of fast heating by quenching of Infrasonic DeuX electronic states is discussed and the scaling of its main channels with ambient air density is quantified. Infrasonic DeuX -[…]