Simulations and Theory of Lightning Initiation in Low Thundercloud Fields

本研究试图从理论上研究低层雷云场中的闪电起爆问题，这是目前闪电放电物理学中尚未解决的一个基本问题。这项研究承诺回答有关水流星(云中的雨/雪/冰)碰撞的频率、将触发的放电过程或流光活动的类型，以及这种放电活动逃逸并继续在更大规模上发展所需条件的可能性。更好地了解小颗粒周围的电场可能会对粉末涂料和激光打印等行业产生兴趣。这项工作包括培训年轻科学家，并支持本科生的研究。研究人员将首先使用镜像电荷法量化两个球形水流星之间的电场，并使用泊松方程量化两个非球形水流星之间的电场，并将雪崩应用于流光转换准则，以观察流光是否可能启动。其次，研究人员将开发一个流体模型，该模型包括正离子和负离子的连续性方程，以及电子与泊松方程的耦合。第三，研究人员将应用流光模型来描述两个水星之间的流光发展和开放空间的流光逃逸。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This study seeks to theoretically investigate the lightning initiation in low thundercloud fields, that currently represents a fundamental unsolved problem in lightning discharge physics. The research promises to answer questions about the frequency of relevant hydrometeor (rain/snow/ice in cloud) collisions, the kind of discharge process or streamer activity that would be triggered, and the likelihood of conditions required for such discharge activity to escape and continue to develop on larger scales. A better understanding of electric fields around small particles could be of interest to industries like powder-coating and laser printing. The work includes training of young scientists and enables support of undergraduate research. The investigators will, first, quantify the electric field between two spherical hydrometeors using the image charge method and between two non-spherical hydrometeors using the Poisson's equation, and apply the avalanche to streamer transition criteria to observe whether streamer initiation is possible. Second, the investigators will develop a fluid model consisting of continuity equations for positive and negative ions, and electrons coupled with Poisson's equation. Third, the investigators will apply streamer models to describe the streamer development between the two hydrometeors and the streamer escape to open space.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.