The breakdown voltage is deviated from Paschen’s law for gaps with several microns. Hence

taking a typical gap with 4 μm separation

as the research object

we established a simulation model of gas discharge in micro-scale gaps based on PIC-MCC method

and analyzed the influence of the presence or absence of field emission on the discharge form process. The density distribution of different particles

velocity distribution of different particles

and electric field distribution evolution were obtained. Finally

it is elucidated that field emission and subsequent ion enhanced field emission are the main factors for induced gas discharge in gaps with 2 μm to 5 μm separation

but field emission is a direct reason for induced gas discharge in gaps with less than 1μm separation. It is useful for further understand the mechanism of gas discharge in micro-scale gaps.