In order to study the process and micro mechanism of air corona discharge

a two-dimensional axisymmetric hydrodynamic model of needle-plate discharge is established in this paper. The microcosmic process of air positive corona

the space-time distribution of its electric field and charged particles

and the waveform characteristics of discharge pulse are studied. The results show that the pulse current of air positive corona includes three stages

namely

rapid rise

rapid decline

and discharge shock; the rise time of pulse current

the time interval between adjacent pulses

the average peak value and the change trend of peak value can be as the characteristic parameters of discharge current. The further analysis shows that the average amplitude has a positive relation with the ionization coefficient

positive ion mobility and secondary ion mobility

while has a negative relation with adhesion coefficient. The rise time of pulse current and the time interval between adjacent pulses decrease with the increase of positive ion mobility

but they are not affected by the other three model coefficients.