Effects of the dielectric layer on a planar and a coplanar discharge breakdown

There are two influences of a dielectric layer on the breakdown in Paschen' s law The potential difference at the dielectric layer itself enhances the minimum value of firing voltage, while the strong field in the discharge sp ace with a large dielectric constant reduces the firing voltage in a high p ressure range. Specially in a coplanar geometry like AC-PDP [S. Sate et al. : IEEE Trans. Electron Devices 23 (1976) 328.], the firing voltage is shown to be higher due to the non-uniformity of the electric field along with th e thickness of the dielectric layer.