Three-Dimensional Numerical Modeling of Sprite Streamers

雪碧流光的三维数值建模

• 批准号: 2247153
• 负责人: Ningyu Liu
• 金额: $ 47.84万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-01 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247153&HistoricalAwards=false
• 关键词: Three; Dimensional; Numerical; Modeling; Sprite

This award will investigate the fundamental physics of sprite streamers using a recently developed, high-performance plasma discharge fluid simulation code, in close conjunction with the latest high-speed images of sprites. About thirty years ago, it was discovered that powerful lightning strokes can cause spectacular Transient Luminous Events (TLEs) in the earth’s upper atmosphere. Sprites are one of the TLEs. Subsequent research has found that sprites share similar physical characteristics as those commonly known spark discharges near the ground. They, however, are much larger and last much longer, because they occur in an environment with greatly reduced air density. Sprites can cause significant modifications of the physical and chemical properties of the upper atmosphere, capable of affecting the propagation of certain radio frequency bands for long-range communications. High-resolution images of sprites have revealed that they consist of a large number of plasma filaments known as streamers. It has been recognized that understanding streamer physics holds the key to learning sprite dynamics and effects. This project will utilize an advanced computer simulation tool to study various poorly understood streamer processes. It will greatly advance our understanding of the physics and effects of sprites. The study will advance knowledge of dielectric breakdown and transient plasma discharges and improve lightning forecast and safety. The software developed in this project will be open source. Graduate and undergraduate students will be supported and involved in this research project, thus contributing to STEM workforce development. This project will investigate streamer branching, collisions between streamer heads, collisions between streamer heads and streamer channels, effects of neutral density perturbations on streamer dynamics, and interaction between streamers and the lower ionosphere. Various three-dimensional simulations will be performed using a high-performance plasma discharge fluid code called AMPLIFI (Adaptive Modeling of PLasma Initiation, Filamentation and Interaction), which was recently developed, to understand the physics of these processes, their roles in sprite dynamics, their electrical and optical effects, and their dependence on the ambient environment. This project will also provide critical information for interpreting high-speed images of sprites and understanding the implications. Concrete knowledge of the dependence of sprite streamer dynamics on ambient neutral or electrical conditions will be obtained, and this will enable the development of potentially powerful remote sensing approaches to studying the mesosphere/D region ionosphere by observing sprites. The study of the neutral density perturbation effects on sprite streamer dynamics will also reveal a novel neutral-ion coupling mechanism enabled by a strong electric field.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.

该奖项将使用最近开发的高性能等离子体放电流体模拟代码，结合最新的精灵高速图像，研究精灵流光的基本物理学。大约30年前，人们发现强大的雷击可以在地球高层大气中引起壮观的瞬态发光事件（TLEs）。精灵是TLE之一。 随后的研究发现，精灵有着与地面附近常见的火花放电相似的物理特征。然而，它们更大，持续时间更长，因为它们发生在空气密度大大降低的环境中。精灵可以导致高层大气的物理和化学性质发生重大变化，能够影响远程通信的某些无线电频段的传播。精灵的高分辨率图像显示，它们由大量被称为流光的等离子体细丝组成。人们已经认识到，理解流光物理学是学习精灵动态和效果的关键。这个项目将利用先进的计算机模拟工具来研究各种鲜为人知的拖缆过程。它将极大地推进我们对精灵的物理和效果的理解。 这项研究将提高对介质击穿和瞬态等离子体放电的认识，并改善雷电预报和安全。该项目开发的软件将是开源的。 研究生和本科生将得到支持，并参与这一研究项目，从而有助于干劳动力的发展。 该项目将研究流光分支、流光头之间的碰撞、流光头与流光通道之间的碰撞、中性密度扰动对流光动力学的影响以及流光与低电离层之间的相互作用。各种三维模拟将使用一个高性能的等离子体放电流体代码称为AMPLIFI（等离子体启动，丝状化和相互作用的自适应建模），这是最近开发的，以了解这些过程的物理，它们在精灵动力学中的作用，它们的电学和光学效应，以及它们对周围环境的依赖。该项目还将为解释精灵的高速图像和理解其含义提供关键信息。将获得精灵流光动力学对环境中性或电气条件的依赖性的具体知识，这将使开发潜在的强大的遥感方法，通过观测精灵来研究中间层/D区域电离层。 中性密度扰动对精灵流光动力学影响的研究还将揭示一种新的中性离子耦合机制，该机制由强电场实现。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。