Simulations and Theory of Lightning Initiation in Low Thundercloud Fields

本研究试图从理论上探讨低雷雨云场中的闪电起始，这是目前闪电放电物理学中尚未解决的一个基本问题。 该研究有望回答有关相关水凝物（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，以及此类放电活动逃逸并继续在更大范围内发展所需条件的可能性等问题。 更好地了解小颗粒周围的电场可能对粉末涂料和激光打印等行业感兴趣。 这项工作包括培训青年科学家，并支持本科生的研究。研究人员将首先使用图像电荷方法量化两个球形水凝物之间的电场，并使用泊松方程量化两个非球形水凝物之间的电场，并将雪崩应用于流光过渡标准，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，包括正负离子的连续性方程，以及与泊松方程耦合的电子。 第三，研究人员将应用流注模型来描述两个水凝物之间的流注发展和流注逃逸到开放空间。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.