Although the application range of traditional Boltzmann equation is

strictly speaking

only applicable for the system consisting of the neutral gas molecules

its application is still suitable in the system of common non-equilibrium plasma including the ones flowing under the atmospheric pressure if its results are suitably corrected. In order to explain the reason

the process of establishing Boltzmann equation is analyzed. It can be seen from the results that in order to extend the application range of the Boltzmann equation from neutral gas molecules to the non equilibrium plasma under various conditions without any man-made correction

meanwhile

for final results

the produced item and the loss item are needed to be added into the back of the collision term in the right of Boltzmann equation. The Boltzmann equation with the added generation item and loss item is a universal equation

which can be applicable for both the gas molecular system and the non equilibrium plasma system.