When calculating the ion flow field in engineering

some assumptions are usually used to simplify the calculation

and the microscopic mechanism of corona discharge is not related to the macroscopic characteristics. The ionosphere is the dominant region of corona discharge. Therefore

we established a coaxial cylindrical electrode model of fluid dynamics coupled Poisson equation by using the average discharge parameters

calculated and analyzed the electric field distribution in the ionosphere and the microscopic physical change process of each particle during negative corona discharge

and explained the pulse discharge mechanism of electric field intensity and corona current on the surface of negative conductor. It is found that negative ions play a key role in the discrimination of electric field intensity and ionospheric thickness at the ionosphere. Moerover

the ionospheric thickness of different radius wires is simulated and calculated

and the variation law between the radius of the wire and the ionospheric thickness is obtained. The results show that when the radius of the wire is large

the ionospheric thickness of the wire cannot be ignored. The ionospheric boundary is proposed as the iterative starting point of the numerical algorithm of ion flow field

which can improve the calculation speed and iterative convergence. Taking the actual working condition wire as an example

we calculated the influence of different temperature

pressure and humidity on the ionospheric thickness

and analyzed the reasons for the change of ionospheric thickness caused by different environmental parameters. The research results of this paper can provide a theoretical basis for the microscopic physical mechanism of corona discharge of transmission lines

the ionospheric thickness of the conductor during negative corona discharge is calculated under different environmental parameters

which provides a reference for the calculation of ion flow field in engineering.