大气压空气纳秒脉冲阵列式线-线SDBD等离子体的电学及发射光谱特性研究

提出了一种阵列式线-线沿面介质阻挡放电结构，利用双极性高压纳秒脉冲电源，在大气压空气中激励产生了相对大面积的放电等离子体。其中，高压电极、地电极均为圆柱形金属，放电反应器由20组相间排列的阵列式线型高压电极和套有介质管的阵列式线型地电极组成。利用电压探头、电流探头、示波器等测量了放电电压和放电总电流，并计算得出了放电的实际电流。利用光纤、光栅光谱仪、CCD等测量了波长范围在300～440 nm和766～778 nm的发射光谱，即氮分子第二正带N₂ (C3Π_u→B3Π_g)包括Δν= +1, 0, -1, -2, -3、氮分子离子第一负带N+₂(B2Σ+_u→X2Σ+_g)，N₂ (B3Π_g→A3Σ+_u)和O (3p5P→3s5S₂)的发射光谱。比较了氮分子第二正带N₂ (C3Π_u→B3Π_g)的各个振动峰和各个活性物种的发射光谱强度，以及这些发射光谱强度随着脉冲峰值电压的变化。测量了N₂(C3Π_u→B3Π_g, 0-0)的二次、三次衍射光谱，与原始光谱在转动带、背景光谱等方面进行了比较，并计算了二次衍射和原始光谱之间的峰值比。利用氮分子第二正带N₂ (C3Π_u→B3Π_g, Δν=+1, 0, -1, -2)和氮分子离子第一负带N+₂ (B2Σ+_u→X2Σ+_g, 0-0)模拟了等离子体的转动温度和振动温度，对模拟结果进行了比较，并研究了脉冲峰值电压对等离子体振动温度和转动温度的影响。通过测量放电的电压和计算得到的放电电流发现，当脉冲峰值电压为22 kV，脉冲重复频率为150 Hz时，阵列式线-线沿面介质阻挡放电的放电电流在正脉冲、负脉冲两个方向上均可达75 A左右。通过诊断放电等离子体的发射光谱发现，在测量的波长范围内，放电产生的活性物种主要有氮分子第二正带N₂ (C3Π_u→B3Π_g)、氮分子离子第一负带N+₂(B2Σ+_u→X2Σ+_g)，N₂ (B3Π_g→A3Σ+_u)和O (3p5P→3s5S₂)。在脉冲峰值电压22～36 kV的变化范围内，氮分子第二正带N₂(C3Π_u→B3Π_g, 0-0)的发射光谱强度始终保持最强，N₂ (B3Π_g→A3Σ+_u)次之，而氮分子离子第一负带N+₂(B2Σ+_u→X2Σ+_g)和O (3p5P→3s5S₂)的发射光谱强度较弱。同时，当脉冲峰值电压升高时，氮分子第二正带N₂ (C3Π_u→B3Π_g)的所有振动峰，以及氮分子离子第一负带N+₂(B2Σ+_u→X2Σ+_g)，N₂ (B3Π_g→A3Σ+_u)和O (3p5P→3s5S₂)的发射光谱强度均随之升高。通过比较氮分子第二正带N₂(C3Π_u→B3Π_g, 0-0)的原始、二次衍射、三次衍射光谱发现，二次、三次衍射光谱的转动带更清晰，但三次衍射光谱的背景更强，因此氮分子第二正带N₂(C3Π_u→B3Π_g)的二次衍射光谱更有利于模拟等离子体的转动温度。通过比较模拟得到的振动温度和转动温度发现，氮分子第二正带N₂ (C3Π_u→B3Π_g, Δν=-2)在N₂ (C3Π_u→B3Π_g)四个谱带Δν=+1, 0, -1, -2中最适于模拟等离子体振动温度，而利用氮分子离子第一负带N+₂ (B2Σ+_u→X2Σ+_g,0-0)模拟得到的等离子体转动温度要比N₂ (C3Π_u→B3Π_g, Δν=-2)的模拟结果高约10～15 K。同时，当脉冲峰值电压升高时，由N₂ (C3Π_u→B3Π_g, Δν=-2)和N+₂ (B2Σ+_u→X2Σ+_g, 0-0)模拟得到等离子体的转动温度均出现了略微上升的趋势，而利用N₂ (C3Π_u→B3Π_g, Δν=-2)模拟得出的振动温度则略微下降。

Electrical and OES Characters of Nanosecond Pulsed Array Wire-to-Wire SDBD Plasma in Atmospheric Air

In this paper, an array wire-to-wire surface dielectric barrier discharge is reported, and discharge plasma with a relative large area is excited by a high-voltage nanosecond pulse power in atmospheric air. The high-voltage and ground electrodes are made of cylindrical metal, and the discharge structure is composed of 20 groups of alternately arranged array high-voltage and ground electrodes covered with dielectric tubes. The applied voltage and total discharge current are measured by high-voltage and current probes, and displayed on oscilloscope. And the discharge current is calculated. The optical emission spectra within the wavelengths of 300～440 and 766～778 nm are measured by fiber, spectrometer, and CCD, namely, the spectra of N₂ (C3Π_u→B3Π_g) including the bands of Δν=+1, 0, -1, -2, -3, N+₂(B2Σ+_u→X2Σ+_g), N₂ (B3Π_g→A3Σ+_u), and O (3p5P→3s5S₂). The emission intensities are calculated, and every peak of N₂ (C3Π_u→B3Π_g) and four active species are compared. The effects of pulse peak voltage on the emission intensities are also investigated. The second and third diffraction spectra are measured and compared with the original spectra of N₂ (C3Π_u→B3Π_g, 0-0) in the aspects of rotational bands and background spectra. The ratios of peak value between the second diffraction and original spectra of N₂ (C3Π_u→B3Π_g, 0-0) are calculated. The rotational and vibrational temperatures are simulated and compared by N₂ (C3Π_u→B3Π_g, Δν=+1, 0, -1, -2) and N+₂ (B2Σ+_u→X2Σ+_g, 0-0), and the effects of pulse peak voltage are investigated. According to the applied voltage and calculated discharge current, the discharge current of array wire-to-wire surface dielectric barrier discharge is about 75 A in both positive and negative directions, when pulse peak voltage is 22 kV and pulse repetition rate is 150 Hz. The optical emission spectra show that the main active species of discharge plasma are N₂ (C3Π_u→B3Π_g), N+₂(B2Σ+_u→X2Σ+_g), N₂ (B3Π_g→A3Σ+_u), and O (3p5P→3s5S₂) during measured ranges. During the range of 22～36 kV of pulse peak voltage, the emission intensity of N₂ (C3Π_u→B3Π_g, 0-0) keeps the highest, then it is N₂ (B3Π_g→A3Σ+_u), and those of N+₂(B2Σ+_u→X2Σ+_g) and O (3p5P→3s5S₂) are relatively weak. And when the pulse peak voltage increases, the emission intensities of all vibrational peaks of N₂ (C3Π_u→B3Π_g), N+₂(B2Σ+_u→X2Σ+_g), N₂ (B3Π_g→A3Σ+_u), and O (3p5P→3s5S₂) increase. Comparing the original, second, and third diffraction spectra of N₂ (C3Π_u→B3Π_g, 0-0), it is found that the rotational bands of the second and third diffraction are clearer than those of original spectra, and the backgrounds of third diffraction are more intense than those of second diffraction, which means that it is more suitable to simulate rotational temperatures by the second diffraction spectra of N₂ (C3Π_u→B3Π_g). Comparing the simulated vibrational temperatures, N₂ (C3Π_u→B3Π_g, Δν=-2) is the most suitable one amongthe four bands of N₂ (C3Π_u→B3Π_g, Δν=+1, 0, -1, -2), and rotational temperatures simulated by N+₂ (B2Σ+_u→X2Σ+_g, 0-0) are higher than those of N₂ (C3Π_u→B3Π_g, Δν=-2) by 10～15 K. Besides, when the pulse peak voltage increases, the rotational temperatures simulated by N+₂ (B2Σ+_u→X2Σ+_g, 0-0) and N₂ (C3Π_u→B3Π_g, Δν=-2) both increase, and the vibrational temperatures simulated by N₂ (C3Π_u→B3Π_g, Δν=-2) decrease.