大气压空气中纳秒脉冲弥散放电实验研究

Experimental Study on Nanosecond-pulse Diffuse Discharge in Atmospheric Air

为了能够在大气压下获得大面积高能量密度的低温等离子体,近年来弥散放电的研究与应用受到广泛关注。采用基于磁脉冲压缩系统的重复频率ns脉冲电源来激励大气压空气中尖板电极结构放电,通过电压电流测量和发光图像拍摄研究了弥散放电的特性。实验结果表明,在常温常压和高重复频率下能够获得大面积均匀的弥散放电,气隙距离增大或减小时,弥散放电分别向电晕放电与火花放电转换。重频ns脉冲放电存在极性效应,电极的小曲率半径处施加负脉冲时需要比正脉冲更高的电场强度才能获得弥散放电。此外,弥散放电的强度随着脉冲上升时间的增大而减弱。因此合适的气隙距离、极不均匀电场的强场处施加正极性脉冲和较陡的脉冲上升时间有利于获得较为强烈的弥散放电。

Nanosecond-pulse can generate extremely high power density and large-scale non-thermal plasma, which attracts attentions. We used a repetitive nanosecond-pulse generator based on magnetic compression system to drive gas discharge in atmospheric air with a tube-to-plane gap, and investigated characteristics of diffuse discharge by the measurement of electrical discharge parameters and discharge images. The experimental results show that large scale diffuse discharge can be obtained at atmospheric pressure with high pulse repetition frequency, and the diffuse discharge will transit to corona or spark mode with increasing or decreasing air gap spacing, respectively. Polarity effect occurs in repetitive nanosecond-pulse discharge, with a negative polarity of the electrode of small curvature radius, diffuse discharge needs more electric field for excitation than that with a positive polarity. In addition, intensity of the diffuse discharge decreases with the increase of the rise-time of pulse. Therefore, the diffuse discharge is likely available under certain conditions of proper air gap, high electric field with positive pulse, and fast rise time.