Study on homogeneous nanosecond-pulse dielectric barrier discharge in atmospheric air

Dielectric barrier discharge (DBD) in atmospheric air has a promising application for plasma excitation, and a homogeneous discharge is important for dielectric barrier discharge applications. Consequently, a repetitive nanosecond-pulse generator with 40 ns rise time and 70 ns pulse duration was used to drive dielectric barrier discharge in air at atmospheric pressure. Discharge characteristic, images, and emission spectra of the nanosecond-pulse DBD were presented. Especially, fast images were taken using one ICCD camera with an exposure time of 2 ns. The experimental results show that the discharge is in a homogeneous mode when the air gap is 1 mm, and it will be changed to a filamentary mode when the air gap is increased to 4 mm. The emission spectra of the discharge indicate that the spectra are mainly from nitrogen species of second positive system below 400 nm. The results indicate that the usage of nanosecond pulses can produce a stable dielectric barrier discharge in atmospheric air, especially results in a homogeneous discharge under some conditions, and the excited plasma is a low-temperature plasma with a highly non-equilibrium state.