The invention relates to a compact device for maximizing the volume of cold plasma produced in air. According to the invention, the device comprises flat electrodes (4, 5, 6, 7) defining several adjacent discharge intervals (1, 2, 3), the electrodes being of two types which alternate spatially: high voltage electrodes (4, 6) connected in parallel to a high voltage source and ground electrodes (5, 7) connected to the installation grounding, between the electrodes there being some dielectric barriers (8).