The study of streamer discharges during air-gap breakdown processes under a tip-to-tip electrode configuration is of significant importance. A numerical analysis model for 100 mm air-gap needle-to-needle streamer discharges is established based on drift-diffusion fluid equations governing electron and positive/negative ion transport in air. The model incorporates 110 reaction processes

including electron impact ionization

recombination/attachment

dissociation quenching reactions

and photoionization mechanisms. The streamer propagation velocity

electric field distribution

and electron density characteristics under the needle-to-needle configuration are analyzed and compared with those of a conventional needle-to-plane structure. Furthermore

the cathode-side pre-ionization phenomenon and the charge distribution of particle clouds in the needle-to-needle configuration are investigated

with emphasis on the influence of the pre-ionization region on streamer development. Finally

the effects of applied voltage amplitude on the streamer channel radius

propagation velocity

and head electric field strength are examined. The results show that

compared with the needle-to-plane configuration

the needle-to-needle configuration exhibits a cathodic pre-ionization region caused by localized charge accumulation in the particle cloud

which can reduce the streamer propagation velocity by up to 4.5%. As the applied voltage increases from 80 kV to 120 kV

the streamer propagation velocity increases by 150%

and the channel radius expands by 300%

while the peak electric field strength at the streamer head decreases by 12%.