CEDAR: Mechanisms and Effects of Terrestrial Gamma-Ray Flashes

根据这项赠款，将对陆地伽马射线闪光(TGFs)的机制和影响进行为期3年的理论研究。最近对拉马蒂高能太阳光谱成像仪(RHESSI)航天器上的TGFs的观测表明，有必要为它们的产生对目前的模型进行修订。该项目将基于快速移动的闪电回击辐射的电磁脉冲(EMP)产生失控电子雪崩的可能性，研究产生TGFs的新机制。拟议的计划建立在由提议团队开发的先前的转化生长因子生产模型的基础上，主要目标是确定电磁脉冲驱动机制的量化可行性。这包括开发一个基于运动学的蒙特卡罗模型，该模型描述了闪电电磁脉冲对相对论电子的部分同步失控加速。此外，将把模型结果与实验数据进行比较，包括在RHESSI上观察到的转化生长因子通量和能谱。该项目是跨学科的，因为它将促进对发生雷暴的较低(中性)大气与中间层和电离层较高海拔的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，这一研究项目的结果将产生超出大气科学的更广泛的科学影响。

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.