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Study of Uniform and Filamentary Streamers Under Knife-Plate Geometry: Measurements And Numerical Simulation

Homogeneous discharge with a large volume is a desirable plasma source for extensive applications. Nanosecond (ns) pulsed high voltage (HV) excitation is believed to be a promising strategy to obtain homogeneous or diffuse discharges at atmospheric pressure. In this letter, with a knife-plate geometry driven by a ns-pulsed generator, a diffuse plasma sheet with a gap distance of 1 cm and a length of 12 cm is generated at the atmospheric air, maintaining a low gas temperature of ~330 K. However, time-resolved images reveal that the diffuse discharge for naked eye consists of multiple individual streamers, which propagate asynchronously from knife (HV) to plate (ground). The appearance of two processes, namely primary and secondary streamers, is consistently verified by discharge images, electric field evolution, and fluid simulation. This further proves that the entire discharge belongs to an intermediate state between corona and spark. This paper is helpful for deeply understanding the intrinsic characters of similar diffuse discharges and optimizing parameters in practical applications.