Improvement of Spatial Uniformity of Nanosecond-Pulse Diffuse Discharges in a Multi-Needle-to-Plane Gap

Large-scale non-thermal plasmas generated by nanosecond-pulse discharges have been used in various applications,including surface treatment,biomedical treatment,flow control etc.In this paper,atmospheric-pressure diffuse discharge was produced by a homemade nanosecond-pulse generator with a full width at half maximum of 100 ns and a rise time of 70 ns.In order to increase the discharge area,multi-needle electrodes with a 3×3 array were designed.The electrical characteristics of the diffuse discharge array and optical images were investigated by the voltage-current waveforms and discharge images.The experimental results showed that the intensity of diffuse discharges in the center was significantly weaker than those at the margins,resulting in an inhomogeneous spatial uniformity in the diffuse discharge array.Simulation of the electric field showed that the inhomogeneous spatial uniformity was caused by the non-uniform distribution of the electric field in the diffuse discharge array.Moreover,the spatial uniformity of the diffuse discharge array could be improved by increasing the length of the needle in the centre of the array.Finally,the experimental results confirmed the simulation results,and the spatial uniformity of the nanosecond-pulse diffuse discharge array was significantly improved.