Relativistic Runaway Discharges in the Earth's Atmosphere

地球大气中的相对论失控放电

• 批准号: 2341623
• 负责人: Victor Pasko
• 金额: $ 77.93万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-02-01 至 2029-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2341623&HistoricalAwards=false
• 关键词: Relativistic; Runaway; Discharges; Earth; Atmosphere

The proposal aims at advancing the knowledge of spectacular naturally occurring phenomena related to lightning activity in the Earth’s atmosphere. Several of such processes are known to the community as sprites, blue and gigantic jets etc. These have attracted the attention of several citizen scientists all over the globe. One such phenomenon, which is still not completely understood is referred to as terrestrial gamma-ray flashes or TGFs. During these events, bursts of X-rays with high energy are generated. The main goal of this research is to develop theoretical work that will shed light on the sources of TGFs. This inter-disciplinary work combines concepts of plasma physics as well as atmospheric processes. It may be relevant to the development of new X-ray sources with possible implications on medical imaging processes. The proposed work will result in the training of a graduate student and will be part of the doctorate thesis. The main motivation for the proposed work results from some recent observations of TGF’s and exploring the underlying physical processes responsible for these events. The core physical process leading is avalanche multiplication of electrons accelerated by force exerted by electric field. In geophysical context the field is generated either as ambient field due to thundercloud electrification or produced by lightning leaders. These electrons gain energy from the electric field and experience quick multiplication in ionizing collisions. In relativistic regime these electrons can radiate energetic photons (X-rays) as they scatter by nuclei of nitrogen and oxygen atoms in air. The radiation is referred to as braking or bremsstrahlung radiation. These X-rays are radiated in all directions and some fraction is radiated backwards with respect to electron motion. These X-rays can produce seed electrons due to photoelectric effect and this leads to strong amplification of the original avalanche. This process is referred to as feedback process. It was discovered recently that these effects occur on very small spatial scales in good agreement with existing observations. This project investigates the exact physical regimes which lead to observed phenomena. The education and transfer of knowledge will benefit from the proposed activity through the mentoring of students.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.

该提案旨在增进对与地球大气层中闪电活动有关的壮观自然现象的了解。一些这样的过程是众所周知的社会精灵，蓝色和巨大的喷气机等，这些吸引了几个公民科学家的注意力遍布地球仪。其中一种尚未完全理解的现象被称为地面伽马射线闪光或TGFs。在这些事件中，产生了高能量的X射线爆发。本研究的主要目标是发展理论工作，阐明TGF的来源。这项跨学科的工作结合了等离子体物理学和大气过程的概念。它可能与新的X射线源的发展有关，可能对医学成像过程产生影响。拟议的工作将导致培养一名研究生，并将成为博士论文的一部分。提出的工作结果的主要动机，从一些最近的观察TGF的和探索的基本物理过程负责这些事件。其核心物理过程是电子在电场作用下加速的雪崩倍增。在地球物理学的背景下，由于雷暴云带电或闪电先导产生的环境场产生的场。这些电子从电场中获得能量，并在电离碰撞中快速倍增。在相对论范围内，这些电子可以辐射高能光子（X射线），因为它们被空气中的氮原子和氧原子的原子核散射。这种辐射称为制动辐射或韧致辐射。这些X射线在各个方向上辐射，并且相对于电子运动，一些部分向后辐射。由于光电效应，这些X射线可以产生种子电子，这导致原始雪崩的强烈放大。 这个过程被称为反馈过程。最近发现，这些影响发生在非常小的空间尺度上，与现有的观测结果非常一致。该项目研究导致观察到的现象的确切物理机制。通过对学生的指导，教育和知识转移将从拟议的活动中受益。该奖项反映了NSF的法定使命，并被认为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来支持。