激光干涉法在空气间隙放电参数测量中的应用

Application of Laser Interferometry to Parameters Measurements in Air Gap Discharges

空气间隙放电现象物理过程复杂,利用先进手段对其关键参数进行测量具有重要意义。搭建了一套基于激光干涉原理的Mach-Zehnder干涉仪放电参数测量系统,利用干涉条纹图像可推算测试区域的折射率分布,进而可得到温度、粒子密度等热物理参数。以空气电弧为主要研究对象,对尖–板电极交流电弧（约0.1 A）和电焊机直流电弧（30 A）进行诊断实验,建立局部热力学平衡模型,得到其温度和电子密度等参数的径向分布,前者的弧心温度约为3 000~6 000 K,后者的弧心温度约为12 000 K。另外,还初步得到了空气间隙放电通道的干涉条纹图像。实验结果验证了激光干涉法在空气放电参数测量研究中的可行性,为该方法在长空气间隙放电研究中的应用奠定了基础。

The physical processes of air gap discharges are quite complex and experimental investigation of the evolution of discharges is necessary to establish the theoretical models. A Mach-Zehnder interferometer was set up to obtain the thermodynamic parameters such as temperature and particles concentration, using the radial distribution of refractive index calculated from fringe images. Research on air arcs was conducted to verify the measurements. A local thermal equilibrium（LTE） model was established to obtain the relationship between temperature and densities of main particles such as electron and ions which determine the refractive index of arc plasma. Both AC arcs（0.1 A） and DC arcs（30 A） diagnostic experiments were conducted. The center temperature of the former ones vary from 3 000 K to 6 000 K, while of the latter ones is about 12 000 K. Moreover, fringe images of long air gap discharges have been obtained preliminarily in laboratory testing. This study laid a solid foundation for the follow-up researches on long air gap discharges.