To investigate the breakdown time delay characteristic of the trigger gap in a pre-ionization gas switch in the presence and absence of superposed transverse electric field produced by main gap

using a 2 D code based on fluid model and finite volume method

we simulated the breakdown process of 0.5 mm and 1 mm trigger gap in N2 under gas pressure from 0.1 MPa to 0.7 MPa

the rising rate of input voltage divided by gas pressure d（u/p）/dt=0.8 k V/（ns·MPa） and 0.4 kV/（ns·MPa）

in the presence and absence of superposed transverse electric field when the voltage division ratio between main gap and trigger gap varied. Meanwhile

we compared the results with experimental data. The results indicate that because d（u/p）/dt influences the changing process of Eav/p

which is the normalized average electric field in the trigger gap

gas pressure

gap distance and the time when initial electrons emerge are main factors of breakdown time delay when d（Eav/p）/dt is fixed. Superposed transverse electric field will enhance the electric field in the trigger gap and accelerate the development of electron avalanche

but it can also lead to the transverse drifting of electrons

which increases the breakdown time delay. Reducing the voltage division ratio and increasing d（u/p）/dt and the diameter of the anode can weaken the influence of transverse electric field.