空气中先导-流注放电发展随机特性及分支机理

对于不同尺寸的气体间隙放电，当流注或先导发展时，都存在着分支（或分叉）现象。先导-流注放电分支机理是高压输变电工程外绝缘设计和雷电屏蔽问题的研究基础。由于放电分支随机性强，以往关于分支三维结构缺乏高效率的还原方法；影响大气压放电分支的关键参数——电子密度测量挑战较大。因此先导-流注放电分支的机理尚不清楚，对其进行纯流体三维模型仿真计算量太大。本项目拟搭建基于双目机器视觉的放电光学形态观测系统，利用关键特征提取和立体匹配技术获得先导-流注放电三维发展分支参数；搭建Shack-Hartmann型激光波前传感器测量平台定量研究先导和空间茎（space stem）的电子密度分布；构建融合宏观电气几何模型和微观流体模型的负先导三维分支模型，其中流体模型考虑随机光电离的作用机制。通过实验和建模研究揭示先导-流注放电随机发展和分支机理，推动输变电工程的外绝缘精细设计、雷电防护发展以及气体放电理论进步。

The branching (or bifurcation) phenomenon of electric discharges is common in gas gaps with different sizes when streamers or leaders propagate. The research on the leader-streamer discharge branching will lay the foundation for the external insulation design and lightning shielding performance of electric power transmission systems. Due to the randomness of tortuous discharge channels, the reconstruction of their three-dimensional structure is not efficient in the past. One of the key parameters, affecting the discharge branching, is the electron density. However, it is very challenging to measure it in atmospheric air. Hence, the mechanism of leader-streamer discharge branching phenomena is still unclear and the 3D fluid model requires a large computational load. In this project, we are going to build a discharge optical morphological observation system based on machine vision technology. The statistics of three-dimensional development and branching parameters of leader-streamer discharges in the laboratory can be obtained by the key feature extraction and stereo matching approach. A Shack-Hartmann laser wavefront sensor measurement system will be built up to measure the electron density of space stems and the negative leaders. A three-dimensional branching model of negative leader discharges will be established, which combines the macroscopic electrical fractal model and the microscopic fluid model. The fluid model considers the electron source of random photoionization. Finally, the experimental and theoretical studies will reveal the branching mechanism of leader-streamer discharges. It will also promote the development of the external insulation design, lightning protection for power transmission projects and help advancing of long gap discharge theory.