雷电先导放电通道内电场和电荷的分布特征

Distribution features of the electric field and charge density in the lightning leader channel

针对自然雷电观测数据在先导放电通道内部电特性方面存在的欠缺,基于雷电先导放电与长间隙电弧放电之间的类似性,对雷电先导放电通道内轴向电场和电荷密度的分布情况进行了理论研究。结果表明:先导通道内任意一点的轴向电场均会在其形成后随着时间按近似指数规律衰减,直至达到一个稳态值。对于稳定的先导段,可近似认为其内部的轴向电场是一个恒定量。先导通道内的电荷密度基本上由先导的起始端至头部逐渐增大,在先导的头部附近达到最大值。注入到先导通道内的电荷总量则会随着先导长度的增加而不断增大,且增长的速度也会逐渐加快。

Aiming at the shortage of applying nature lightning observation data onto the research of electri- cal characteristics within lightning leader channels, the axial electric field intensity and charge distribu- tion along the leader are analyzed according to the similarity between lightning leader discharge and long air gap discharge. The theoretical calculation results show that the axial electric field at any observation point of the leader channel decays exponentially after its formation and finally reaches a stable value through time. Therefore, it is reasonable to regard the axial electric field intensity as a constant for the sta- ble leader segment. Meanwhile, the charge density along the leader basically increases gradually from the root to the tip and finally reaches its maximum near the tip of the leader. The total charge injection to the leader and the relevant increment speed both increases gradually with the extension of the leader.