Unraveling the Runaway Electron Distribution Emitted by Lightning and Laboratory Discharges

解开闪电和实验室放电发射的失控电子分布

基本信息

批准号：
1917069
负责人：
Caitano da Silva
金额：
$ 34.4万
依托单位：
New Mexico Institute of Mining and Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2024-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1917069&HistoricalAwards=false
关键词：
Unraveling Runaway Electron Distribution Emitted

项目摘要

One of the most fascinating discoveries in atmospheric physics is that thunderstorms may work as particle accelerators, producing intense fluxes of energetic radiation, which take different forms, such as: X-ray flashes emitted from the descending lightning channels, bursts of gamma rays observed at satellite altitudes known as terrestrial gamma-ray flashes (TGFs), and minute-long gamma-ray glows that terminate with a lightning bolt. All of these phenomena are different manifestations of bremsstrahlung emissions of the so-called runaway electrons, which are accelerated to high energies despite the collisions with air molecules. It is theoretically plausible that electron acceleration up to runaway energies (via the so-called thermal runaway electron mechanism) can happen at the tips of lightning channels where strong electric fields exist, but a number of questions about the detailed physics and its implications have puzzled researchers in recent years. Although the key role of runaway electrons in atmospheric electricity has been recognized, to date it remains unsettled whether runaway electrons influence the propagation of lightning and laboratory discharges. It also remains unclear if runaway electrons emitted by lightning leaders can seed TGFs. In some instances, X-ray emissions are observed on the ground and correlated to runaway electrons at the tips of descending lightning leader channels. But in some other occasions, powerful ground TGFs are detected instead. It remains a mystery what kind of lightning discharges produces the more energetic gamma emissions (instead of X-rays) and whether the mechanism involves thermal runaway electron generation. The main project goal is to address this knowledge gap with a robust methodology to infer the flux and spectral energy distribution of runaway electrons emitted by lightning and laboratory discharges. This is a 3-step approach that involves: (1) measuring X-ray emissions from short laboratory discharges that efficiently produce runaway electrons, are repeatable, and the electrical properties can be controlled; (2) developing scalable Monte Carlo simulation codes that can unveil the flux and spectral distribution of runaway electrons when driven/validated by the rich dataset collected in step (1); and (3) performing X-ray observations at the Langmuir laboratory mountain-top facility, leveraging the knowledge acquired from steps (1)-(2) to infer the properties of runaway electrons emitted by natural lightning. Additionally, the project has also an educational aim - the research team will develop a freshman-level classroom module to teach basic concepts of electrical breakdown in air via demonstrations with electrical discharges.This project is jointly funded by NSF Physical and Dynamic Meteorology program and the Established Program to Stimulate Competitive Research (EPSCoR).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.

One of the most fascinating discoveries in atmospheric physics is that thunderstorms may work as particle accelerators, producing intense fluxes of energetic radiation, which take different forms, such as: X-ray flashes emitted from the descending lightning channels, bursts of gamma rays observed at satellite altitudes known as terrestrial gamma-ray flashes (TGFs), and minute-long gamma-ray glows that用闪电终止。所有这些现象都是所谓的失控电子的Bremsstrahlung排放的不同表现，尽管与空气分子发生了碰撞，但它们仍会加速到高能。从理论上讲，可以在存在强烈的电场的闪电通道的尖端上发生电子加速度到失控的能量（通过所谓的热失控电子机制），这是可行的，但是近年来，有关详细物理及其含义的许多问题使研究人员感到困惑。尽管已经确认了失控电子在大气电力中的关键作用，但迄今为止，是否会尚未确定失控电子是否影响雷电和实验室排放的传播。目前尚不清楚闪电领导者发出的失控电子是否可以播种TGF。在某些情况下，在地面上观察到X射线排放，并在下降的闪电领导者通道的尖端与失控的电子相关。但是在其他情况下，检测到强大的地面TGF。这仍然是一个谜，什么样的雷电排放产生了更富集的伽玛排放（而不是X射线），以及该机构是否涉及热失去电子电子的产生。主要的项目目标是通过强大的方法来解决这一知识差距，以推断通过雷电和实验室放电发出的失控电子的通量和光谱分布。这是一种三步方法，涉及：（1）测量有效产生失控电子的短实验室放电的X射线排放，可重复，并且可以控制电气性能；（2）开发可扩展的蒙特卡洛模拟代码，该代码可以在步骤（1）中收集的富数据集驱动/验证时揭示失控电子的通量和光谱分布；（3）在Langmuir实验室山顶设施中进行X射线观测，利用从步骤（1） - （2）获得的知识来推断自然闪电发出的失控电子的性质。此外，该项目还具有教育目标 - 研究团队将开发一个新生级教室模块，通过与电气排放的示范进行空气中的电气崩溃的基本概念。该项目由NSF物理和动态的气象学计划共同资助，并由NSF物理和动态的气象计划和既定的计划进行了启发的竞争性研究（EPSCOR）的启发。优点和更广泛的影响审查标准。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Relationship Between Sprite Current and Morphology

DOI：
10.1029/2020ja028930
发表时间：
2021-03-01
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
影响因子：
2.8
作者：
Contreras-Vidal, L.;Sonnenfeld, R. G.;Stenbaek-Nielsen, H.
通讯作者：
Stenbaek-Nielsen, H.

Production of runaway electrons and x-rays during streamer inception phase

DOI：
10.1088/1361-6463/acaab9
发表时间：
2022-12
期刊：
Journal of Physics D: Applied Physics
影响因子：
0
作者：
L. Contreras-Vidal;C. Silva;R. Sonnenfeld
通讯作者：
L. Contreras-Vidal;C. Silva;R. Sonnenfeld

Data-Driven Simulations of the Lightning Return Stroke Channel Properties

雷电回击通道特性的数据驱动模拟

DOI：
10.1109/temc.2022.3189590
发表时间：
2022
期刊：
IEEE Transactions on Electromagnetic Compatibility
影响因子：
2.1
作者：
Taylor, Michael C.;da Silva, Caitano L.;Walker, T. Daniel;Christian, Hugh J.
通讯作者：
Christian, Hugh J.

Lightning effects in the ionosphere over the Arecibo Observatory

阿雷西博天文台上空电离层的闪电效应