Quantifying Energetic Electron Precipitation Driven By Magnetospheric Waves

波存在于太空等离子体中，就像存在于海洋和大气中一样。在这些等离子体中，带电粒子之间的碰撞非常罕见。因此，等离子体波是将能量从一个带电粒子群转移到另一个带电粒子群的主要手段。带电粒子在波浪中“冲浪”。在第一阶中，运动速度略快于引力波的粒子被赋予能量，而运动速度较慢的粒子则向引力波失去能量，导致引力波增长。等离子体波种类繁多，具有不同的性质和不同的源机制。其中三种（等离子体的嘶嘶声、合唱和电磁离子回旋波）被广泛认为在电子辐射带的损耗中起着重要作用，但这是如何发生的，以及每种波对当地时间和径向距离的影响如何，仍然是一个开放的、激烈争论的重要问题。在它们与引力波的相互作用中，电子从它们被困的轨道中散射出来，沿着轨道进入稠密的大气层，在那里它们通过碰撞而消失。这项工作将独立检验实验观测，最重要的是，使用理论工具来理解导致降水的相互作用。由于电子沉淀导致高层大气中的化学变化，并且对于调节环电流和辐射带电子动力学至关重要，因此本提案中要解决的科学问题尤为重要。这笔拨款将支持一位有前途的早期职业女性科学家的进一步培训和发展。研究结果将有助于更广泛的空间物理学和高层大气界、研究中层大气化学的研究人员以及空间环境应用，例如空间自然辐射和人工辐射的主动减缓技术。测试关于特定波粒相互作用和影响它们的空间环境变化的理论观点一直很困难，因为这些波是在磁层的大径向距离上测量的，而它们产生的电子沉淀必须从近地轨道上观察。更复杂的是，等离子体波的混合取决于径向距离和磁场当地时间，此外还有一个尚未确定的函数，即空间天气风暴的严重程度和风暴的阶段。主要研究者（PI）开发了一种创新的技术来分析波强与波驱动电子俯仰角散射损失之间的物理关系，该技术可以直接实现近赤道和低空卫星的共轭观测。该项目采用理论和观测相结合的方法，将对不同能量范围和不同L-MLT区域内每种等离子体波对电子沉淀的定量贡献提供明确的理解。这些结果将为我们更广泛地了解地球周围有害辐射环境的调节机制提供非常重要的贡献。

Waves exist in space plasmas just as in the oceans and the atmosphere. In these plasmas, collisions between charged particles are rare. As a result, plasma waves are a major means of transferring energy from one charged particle population to another. Charged particles "surf" the waves. To first order, those that are moving slightly faster than the waves are energized, while those moving slower lose energy to the waves causing them to grow. There are a wide variety of plasma waves with different properties and different source mechanisms. Three of these (plasmaspheric hiss, chorus, and electromagnetic ion cyclotron (EMIC) waves) are widely believed to play significant roles in the depletion of the electron radiation belts but how this happens and how each contributes with local time and radial distance are still-open and strongly debated questions of fundamental importance. During their interactions with the waves, electrons are scattered out of their trapped orbits and sent on trajectories into the dense atmosphere where they are lost through collisions. The work will independently examine experimental observations and, most importantly, use theoretical tools to understand the interactions leading to the precipitation. The science questions to be addressed in this proposal are particularly important, since electron precipitation leads to chemical changes in the upper atmosphere, and is critical in regulating ring current and radiation belt electron dynamics. The grant will support the further training and development of a promising female early-career scientist. The results will be useful to the broader space physics and upper atmosphere communities, to researchers studying the chemistry of the middle atmosphere, and for space environment applications, such as active mitigation techniques for both natural and artificial radiation in space.Testing theoretical ideas about particular wave-particle interactions and the variations in the space environment that effect them has been difficult because the waves are measured at large radial distances in the magnetosphere while the electron precipitation that they produce must be viewed from low-earth orbit. To complicate matters, the mix of plasma waves depends on the radial distance and magnetic local time but in addition is an as yet to be determined function of the severity of space weather storming, and the phase of the storm. The principal investigator (PI) has developed an innovative technique to analyze the physical relationship between wave intensity and wave-driven electron pitch angle scattering loss, which can be directly implemented using conjugate observations from near-equatorial and low-altitude satellites. This project, which uses both theory and observation, will provide a definitive understanding of the quantitative contribution of each type of plasma wave to electron precipitation within various energy ranges and in different L-MLT regions. The results will provide a highly important contribution to our wider understanding of the mechanisms that regulate the hazardous radiation environment surrounding the Earth.