Simulations and Theory of Streamer Discharges in Transient Luminous Events

瞬变发光事件是发生在地球平流层、中间层和低热层的大规模光学事件，与潜在雷暴中的电活动直接相关。热释光脉冲将对流层耦合到电离层，并可能导致较低热层的加热、加速和光致电离。热释光是一种结构丰富的现象，其基本元素是被称为流光的丝状等离子体。TLE研究对于理解流光放电的微观物理至关重要，也是地球大气化学研究中的一个重要领域。目前对流光的现场观测超过了理论发展的速度，因此对流光启动的许多方面还没有很好的了解。拟议的工作由理论调查组成，这些调查将填补几个知识空白。这项提议还将有助于本科生和研究生的教育和培训。提议者将在现有模型的基础上，在更大的领域内嵌入小范围现象(精灵流光启动)，并添加额外的化学物质。具体地说，PI将研究：1.等离子体不均匀在精灵流光启动中的作用；2.层化大气密度内远距离(~10公里)流光的传播；3.精灵对低电离层化学的影响。这些研究将向工业应用提供有关拖缆(包括臭氧生产和污染控制)和与TLE有关的电离层修改的信息。

Transient luminous events (TLEs) are large-scale optical events occurring in Earth's stratosphere, mesosphere and lower thermosphere that are directly related to electrical activity in underlying thunderstorms. TLEs impulsively couple the troposphere to the ionosphere and may result in heating, acceleration, and photoionization in the lower thermosphere. TLEs are richly structured phenomena, whose fundamental elements are filamentary plasmas called streamers. TLE studies are critical for understanding the microphysics of streamer discharges, and also represent an important area in the research of the chemistry in the Earth's atmosphere. Field observations of streamers currently outpace theoretical developments, and consequently many aspects of streamer initiation are not well understood. The proposed work consists of theoretical investigations that will close several knowledge gaps. This proposal will also contribute to the education and training of undergraduate and graduate students.The proposers will build upon an existing model by embedding small-scale phenomena (sprite streamer initiation) within a larger domain, and adding additional chemistry. Specifically the PI will investigate: 1. the role of plasma inhomogeneities in sprite streamer initiation; 2. propagation of streamers over long distances (~10 km) within stratified air density; and 3. the effects of sprites on lower ionospheric chemistry. These studies will inform industrial applications of streamers (including ozone production and pollution control) and TLE-related ionospheric modification.