多针对板负电晕放电电离区形貌确定

在前期对常压下多针对板负电晕放电伏安特性研究的基础上，利用光学发射光谱(OES)法检测放电产生的N₂发射光谱，研究其电离区形貌。根据N₂发射光谱中峰值最大的第二正态激发谱峰强度I_SPB在高压针电极周围的空间分布，较精确地确定了电离区形貌；在电离区内体积分I_SPB,获知I_SPB与放电电流I之间的关系。实验结果表明，电离区大小随着外加电压U升高而增大；电子雪崩始于距离针尖半径约1 mm处的球面上，并且只在mm量级范围内发展，即电离区的大小为mm量级；电子雪崩沿针尖轴向比沿径向发展范围大，电离区形貌为“子弹”状；I_SPB的积分值与I成二次相系数很小的二阶线性关系，故放电中受激物质主要是N₂；高能电子主要存在于电离区，迁移区中形成电流的带电粒子为离子。

Morphology Determination of Ionization Region in Multi-Needle-to-Plate Negative Corona Discharge

Based on the former work on the current-voltage characteristics of a multi-needle-to-plate negative corona discharge at atmospheric pressure, the present work uses the method of OES (optical emission spectrum) for measuring N2 emission spectrum, and the morphology determination of the ionization region has been investigated. According to the distribution of N2 second positive band's intensity I(SPB), the highest of all bands, the outline of the ionization region was drawn fairly accurately. The relationship between I(SPB) and discharge current I can be obtained through the volume integral of the I(SPB). The experimental results show that the size of the ionization region enhances with the rise of the applied voltage U, and the electron avalanche begins at about 1 mm off the tips of needle electrode and multiplies only in the range of several millimeters, indicating that, the range of the ionization region is at the magnitude of mm. The electron avalanche along the axis of the needle develops farther than that along the radial direction of needle, and the shape of the ionization region looks like a bullet. The integral of I(SPB) is second-order linear to I, with a very second order coefficient, meaning that the main excited substance is N2. Energetic electrons mainly exist in ionization region while ions are the main charged particles to form discharge current in the transfer region.