Discharge characteristics under non-uniform electric field in He, Ar and air at low pressures

We measured dc discharge inception voltage V_i for various electrode configurations in He, Ar and air in vacuum range from 10⁵ to 10^-1 Pa to determine discharge characteristics under a space vacuum environment. By quantitative consideration of the E_i/p distribution in the gap space at the discharge inception, the discharge inception mechanism under non-uniform electric field was investigated in vacuum. At the same time, we observed the discharge profile variation with residual gas pressure and quantitatively analyzed its characteristics, using an image processing technique. Based on the analysis, we found that the dependency of the discharge inception voltage and the length of the discharge path on the residual gas pressure under non-uniform field conditions agreed well with that previously obtained for uniform field conditions