Generation of chorus emissions and acceleration of relativistic electrons associated with magnetic storms

与磁暴相关的合唱发射和相对论电子加速的产生

基本信息

批准号：
17340146
负责人：
OMURA Yoshiharu
金额：
$ 10.18万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

项目摘要

Whistler-mode chorus waves are eletromagnetic emissions that have been observed by spacecraft in the magmetospheres of Earth, Jupiter, Saturn, and Uranus, with frequencies in the range 0.05-0.8 Ω, where Ωis the local electron gyrofrequency. At Earth chorus emissions have also been recorded on the ground Chorus emissions am observed at the time of magnetic field disturbance such as magnetic storms and suhstorms. Chorus waves comprise discrete emissions of short duration (<10-1sec), with frequency typically increasing in time (rising tones), and, when connected to an audio amplifier, sound like bird song at dawn or chirping crickets. Theoretical and modeling studies and observational evidence have established electron acceleration by gyroresonant wave-particle interaction with chorus waves as a key mechanism for generating relativistic (>1 MeV) electrons in the Earth's outer radiation belt during geomagnetically disturbed periods. After nearly four decades of chorus wave observations and numerical studies, only recently have computer simulations been performed that successfully model the generation of chorus emissions with a rising tone. We have found that in the simulation of chorus generation, some resonant electrons are rapidly energized by the processes of relativistic turning acceleration (RTA) and ultra-relativistic acceleration (URA). RTA and URA are particular forms of nonlinear wave trapping of resonant electrons by coherent whistler-mode waves and constitute viable mechanisms for the generation of relativistic electrons in the radiation belts of magnetized planets. The computer simulations reveal that nonlinear wave growth due to the rising tone is the key ingredient in the generation of chorus waves.

惠斯勒模式合唱波是省磁性排放，航天器在地球，木星，土星和天王星的岩质圈中观察到，频率在0.05-0.8Ω中，其中ω是本地电子gyrofrequrecencency。在磁场灾难（例如磁场和弹药）时，在地面合唱的合唱排放中也记录了地球合唱的排放。合唱波完成短持续时间（<10-1sec）的离散排放，频率通常会增加（升起的音调），并且在连接到音频放大器时，听起来像是黎明时的鸟歌或chiring板板球。理论和建模研究和观察性证据通过与合唱波的旋转波颗粒相互作用建立了电子加速度，作为在地球磁障碍时期内在地球外辐射带中产生相对论（> 1 MeV）电子的关键机制。经过将近四十年的合唱波观测和数值研究，直到最近进行了计算机模拟，成功地模拟了以上升语调的合唱发射的生成。我们发现，在合唱生成的模拟中，某些共振电子设备通过相对论转弯加速器（RTA）和超友善的加速度（URA）的过程迅速启发。 RTA和URA是通过连贯的Whistler模式波的非线性波诱捕非线性波诱捕的特殊形式，并且构成了在磁化行星辐射带中生成相对论电子的可行机制。计算机模拟表明，由于音调上升而引起的非线性波生长是合唱波产生的关键成分。