:Coaxial cylinder dielectric barrier discharge is one of the major approaches for plasma-assisted combustion, and it is important to reveal its basic discharge characteristics for optimizing control strategy. Consequently, with high-frequency AC actuation, the characteristics of coaxial cylinder dielectric barrier discharge, including breakdown voltage, discharge image, Lissajous figure, and discharge power, were experimentally studied by changing gas type, gas flow, and power output parameters. The results demonstrate that the curve of breakdown voltage is in a “V” shape with increase of frequency, during which an optimal frequency responding to the lowest breakdown voltage exists. Compared with the effect of frequency, the effect of gas flow on breakdown voltage is not obvious. When the gas flow equals 0, the power consumption increases linearly with frequency and voltage rising, respectively, and the power growth rate varies with voltage faster than with frequency. Moreover, when there is an incoming flow, with the effect of “blow off” and influence on charge distribution, the linearity of power curves varied with frequency and voltage will both decrease. And with increase of gas flow, the discharge intensity will be enhanced and weaken alternately, which results in a “M”-type curve with overall decreasing trend in power consumption. In addition, CH particles are generated under the discharge of methane, and the CH* emission intensity rises linearly with increase of voltage.
KEY WORDS :coaxial cylinder dielectric barrier discharge;high-frequency AC;plasma;discharge characteristics;Lissajous figure;
图1
实验装置结构示意图
Fig.1
Schematic diagram of experimental configuration
为获取激励器放电图像,实验采用Cannon EOS 600D相机于喷嘴正上方垂直向下对放电区域定参数拍摄。当以甲烷为气源放电时,为获取CH*自发辐射强度图像,使用光学滤镜和相机配合的方法拍摄,CH*滤镜参数为430±5 nm,测量辐射带为A2Δ→X2II(0,0)。此外,以纹影仪钨丝灯发光作为稳定光源,只改变相机曝光时长,分析了曝光时长和图像亮度的变化规律,通过拟合表明相机进光量和图像亮度具有良好线性关系。
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