利用上升沿约0.5 μs、半高宽约6 μs、幅值可达40 kV的微秒脉冲电源和上升沿约150 ns、半高宽约300 ns、幅值可达50 kV的纳秒脉冲电源激励大气压弥散放电, 并分别采用刀型和锯齿电极放电。通过电压电流测量和发光图像拍摄, 改变施加电压种类、脉冲重复频率、高压电极结构和气隙距离等参数, 研究了不同条件下弥散放电特性。实验结果表明: 纳秒脉冲电源和微秒脉冲电源均能在大气压空气中激励大面积的弥散放电, 弥散放电面积最大达90 cm2; 放电的均匀性受脉冲参数与电极形状影响显著, 其中刀型电极条件下纳秒脉冲激励的弥散放电均匀性最佳; 相同条件下纳秒脉冲弥散放电的瞬时功率大于微秒脉冲弥散放电, 最高可达275 kW, 而纳秒脉冲弥散放电的能量小于微秒脉冲弥散放电; 保持其他条件不变, 弥散放电传导电流幅值随着气隙距离的增加而降低, 放电强度随着脉冲重复频率的增加而增强, 弥散放电的工作电压范围随着脉冲重复频率的增加显著降低。因此在低频、刀型电极结构中易于获得均匀与较大工作电压范围的大气压弥散放电。

In this paper, a microsecond-pulse generator with a rise time of about 0.5 μs, a pulse width of about 6 μs and an amplitude of up to 40 kV, and a nanosecond-pulse generator with a rise time of about 150 ns, a pulse width of about 300 ns and an amplitude of 50 kV, were used to produce diffuse discharges at atmospheric pressure. A saw-blade and a knife blade were used as the electrodes. Characteristics of diffuse discharges under different conditions, in different cases of the applied voltage, pulse repetition frequency (PRF), anode structure and gap distances, were investigated by analyzing the voltage-current waveforms and discharge images. The experimental results showed that both microsecond-pulse and nanosecond-pulse power supplies could generate large-area diffuse discharges, and the maximum area reached 90 cm2. The uniformity of diffuse discharges were significantly affected by the pulse parameters and anode structure. The best homogeneity could be obtained in the case of a knife blade when nanosecond-pulse generator was used. Furthermore, under the same conditions, the instantaneous power for nanosecond-pulse discharges was larger than that for microsecond pulse discharges, and the largest instantaneous power was 275 kW. However, the energy for nanosecond-pulse discharges was smaller than that for microsecond pulse discharges. In addition, other things being equal, the conduction current decreased with the increase of the gap distance, the discharge intensity increased with the PRF, and the working range of the applied voltage significantly decreased with the PRF. Therefore, it’s most likely to obtain homogeneous diffuse discharges with wide range of working voltages in atmospheric pressure air when the knife blade electrode was used as the anode at low PRF.