CEDAR: Mechanisms and Effects of Terrestrial Gamma-Ray Flashes

一项为期3年的关于地球伽玛射线闪光（TGFs）的机制和影响的理论研究将在这笔拨款下进行。Ramaty高能太阳光谱成像仪（RHESSI）航天器最近对TGFs的观测表明，有必要对当前的模型进行修订。该项目将基于由快速移动的闪电回击辐射的电磁脉冲（EMP）驱动的失控电子雪崩产生的可能性，研究一种产生tgf的新机制。提出的方案建立在之前由提出团队开发的TGF产生模型的基础上，主要目标是确定emp驱动机制的定量可行性。这包括建立一个基于动力学的蒙特卡罗模型，用于描述闪电EMP对相对论性电子的部分同步失控加速。此外，模型结果将与实验数据进行比较，包括在RHESSI上观测到的TGF通量和能谱。这个项目是跨学科的，因为它将促进对雷暴发生的低层（中性）大气与中层和电离层的高海拔电离层之间的电动力学耦合的理解。此外，相对论失控加速是一种全新的粒子加速现象，因此，该研究项目的结果将在大气科学之外产生更广泛的科学影响。

A 3-year theoretical investigation of the mechanisms and effects of Terrestrial Gamma-ray Flashes (TGFs) will be carried out under this grant. Recent observations of TGFs from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spacecraft have demonstrated the need for a revision of the current model for their generation. This project will investigate a new mechanism for the production of TGFs based on the possibility for production of runaway electron avalanche driven by electromagnetic impulses (EMP) radiated by rapidly moving lightning return strokes. The proposed program builds on previous models of TGF production developed by the proposing team and the main objective is to determine the quantitative feasibility of the EMP-driven mechanism. This includes the development of a kinetically based Monte Carlo model of the partially synchronized runaway acceleration of relativistic electrons by the lightning EMP. In addition, model results will be compared to experimental data, including TGF fluxes and energy spectra as observed on RHESSI.This project is cross-disciplinary in that it will advance understanding of the electrodynamic coupling between the lower (neutral) atmosphere, where thunderstorms occur, and the higher altitude ionized layers of the mesosphere and the ionosphere. In addition, relativistic runaway acceleration is a fundamentally new particle acceleration phenomenon and the results of this research project, therefore, will have broader scientific impact beyond atmospheric sciences.