The paper is focused on studying magnesium spinel-doped alumina tapes and their effect on plasma. Developed tapes were made from a mixture of \(15\,\mathrm {vol.\%}\) of \(\mathrm {MgAl_2O_4}\) by the gel tape casting method. Ceramic tapes were sintered at different temperatures from \(1450\,^\circ {\textrm{C}}\) up to \(1700\,^\circ {\textrm{C}}\) . The sintering temperature significantly influenced the material’s grain sizes, but the material’s chemical and phase composition was the same for all sintering temperatures. We measured the surface potential decay and showed that it is not enough to have fast surface potential decay for Atmospheric Pressure Townsend Discharge, but the homogeneity of the surface itself crucially influences the stability of Atmospheric Pressure Townsend Discharge. On the other hand, the ignition voltage of coplanar dielectric discharge was not influenced by the gran size difference.
