PURPOSE: To allow no deterioration of positive characteristic so as to prevent the runaway of current even though discharge gas is large by dividing the surface of a cathode formed in a discharge cell with material having different secondary electron emissivity.

CONSTITUTION: ZnO is coated on a substrate electrode making the low γ portion of a cathode as KL. Thereon the high γ portion KH of, for instance, 80μm in diameter is formed in the center of a cell. Its material is made by solid- dissolving Li2O of 10 molar percentage in LaNiO3. The material is used as thick film ink after being formed into fine particles of, for instance, approximately 0.3μm, and is kneaded with low melting point glass fine particles and fluid vehicle. A 42 percentage by weight of Ni-6 percentage by weight of Cr-Fe alloy plate of 0.15mm thick, for instance, is etching processed, and using the same as an electrode, SiO2-B2O3-PbO-Al2O3-ZnO glass fine particles are electrodeposited thereto. Thereafter the same is fused at 650°C so as to make a partition wall PA whose whole surface is coated with dense dielectric. Thereby no deterioration of positive characteristic is allowed so as to prevent the runaway of current even though discharge gas is large.