多针双极电晕放电形貌发射光谱研究

Morphology Determination of Multi-Needle Bipolar Corona Discharge by OES

利用光学发射光谱(OES)法检测N2发射光谱,研究常压下多针双极电晕放电中高能电子分布。根据N2第二正态激发谱峰ISPB在空间的分布,较精确地确定其电离区形貌,体积分ISPB获知ISPB与放电电流I之间的关系。多针双极电晕放电在高压电极和地电极附近各有一个电离区,各电离区的范围都随电压U的升高而不同程度增大。其中负电晕电离区范围大于正电晕电离区,高压端电子雪崩沿针尖轴向比沿径向发展范围大。正负电晕电离区中ISPB体积分值均与I近似呈一阶线性关系,即ISPB的分布和高能电子浓度相对应。电离区中形成电流的带电粒子为高能电子,迁移区中形成电流的带电粒子为离子。

Using the method of OES（optical emission spectrum） for measuring N2 emission spectrum,the spacial distribution of energetic electrons in multi-needle bipolar corona discharge at atmospheric pressure was investigated.According to the distribution of N2 second positive band＇s intensity ISPB,the outline of ionisation region was drawn accurately.The relationship between ISPB and discharge current I was obtained through the sum of ISPB.There are two ionisation regions in the multineedle bipolar corona discharge.One is near the HV electrode and the other is near the grounded electrode.The ionisation region exists around the needlepoint within 2-3 mm.The volume of ionisation region becomes big with the applied voltage U increasing.The ionisation region of negative corona is bigger than that of positive corona.Near the HV discharge electrode,the outline of electron avalanche is similar to the configuration of electric field lines in the ionisation region,so the electron avalanche along the axis direction of needle develops farther than that along the radial direction.The electric field in the migration area is weak,and the distribution of space charges is large along the radial direction.The sum of ISPB in each ionisation region is second order linear with I,but the quadratic coefficient is very small.So the sum of ISPB is nearly linear with I,the distribution of ISPB is corresponding to the density distribution of energetic electrons.So the charged particles forming the discharge current in ionisation region are electrons.No emission spectrum of N2 can be measured in migration area,so there is no energetic electron.The energetic electrons only exist in ionisation region and the charged particles in migration area are ions.