The Role of Alfven Wave Energy Transport in Geospace Dynamics

太阳系的空间等离子体物理是目前和未来国家和国际航天局飞行任务的一个主要重点。这项研究集中在太阳和行星等离子体环境中活跃的基本过程，等离子体是一种热电离气体，受到磁场的强烈影响。同样的过程在高能等离子体天体物理系统和磁聚变反应堆中也很活跃，它们的影响在地球上和太阳系中的人类探险者通过空间天气的影响而感受到。这项研究的核心是许多重要的悬而未决的问题：无论这是如何通过被称为磁重连的基本过程从磁场中提取能量，为什么太阳(日冕)的外层大气比表面的6000度高数百万度，太阳风如何被加速，或者磁暴如何影响我们的星球并导致粒子加速到相对论速度！这样的过程在整个天体物理宇宙中都很重要，但只有在太阳系中，航天器才能收集推进科学理解所需的数据。围绕地球和太阳系运行的一支国际卫星舰队提供了一个独特的发现机会。这预示着太空研究的黄金时代，而利用这个机会是这里提出的探索基金研究和培训的重点。 我们的研究重点是阿尔芬波在控制地球空间动力学方面的影响。阿尔芬波是一种低频波，其能量传输和信号由磁场引导。尽管人们越来越多地认识到阿尔芬波在这些等离子体系统中普遍存在，但阿尔芬波可能控制一些重要的能量过程的潜力现在才开始详细探索。这在地球上尤其如此，与辐射带动力学有关，也许也与电流系统的动力学有关，也与电离大气和中性大气之间的耦合有关，甚至可能与气候有关。解决阿尔芬波在这些过程中的作用是本提案要解决的具体研究课题。 值得注意的是，根据美国国家科学院2008年的一份报告，太空天气仅在美国就对21世纪的技术基础设施构成了2万亿美元的潜在威胁，包括对电网、卫星系统和通信网络的影响。因此，这里提出的研究和培训也非常及时，因为它完全符合了解、预测和减轻空间天气造成的影响的日益重要的需要。这确保了由拟议研究产生的基础科学发现将另外具有备受瞩目的应用，具有国家乃至国际重要性。

Space plasma physics in the solar system is a major focus for current and future national and international space agency missions. This research focuses on the fundamental processes active in solar and planetary plasma environments, a plasma being a hot ionised gas, strongly influenced by magnetic fields. The same processes are active in high energy plasma astrophysical systems, in magnetic fusion reactors, and their affects are felt on Earth and by human explorers in the solar system through the impacts of space weather. At the core of this research is are numerous important outstanding questions: whether this be the how energy is extracted from magnetic fields through a fundamental process known as magnetic reconnection, why the outer atmosphere of the sun (the solar coronal) is millions of degrees hotter than the 6000 degrees at the surface, how the solar wind is accelerated, or how magnetic storms affect our planet and result in the acceleration of particles to relativistic speeds! Such processes are important throughout the astrophysical universe, but only in the solar system can spacecraft collect the data needed to advance scientific understanding. The operation of a fleet international satellites around the Earth and in the solar system presents a unique opportunity for discovery. This is heralding a golden age for space research, and exploiting this opportunity is the focus of the Discovery Grant research and training proposed here. Our proposed research focuses on the impacts of Alfven waves in controlling geospace dynamics. Alfven waves are low-frequency waves whose energy transport and signals are guided by the magnetic field. Despite an increasing recognition that they are pervasive in these plasma systems, the potential that Alfven waves may control a number of energetically significant processes is only now beginning to be explored in detail. This is especially true at Earth in relation to radiation belt dynamics, and perhaps also to the dynamics of electrical current systems, and coupling between the ionised and neutral atmosphere, and perhaps even to climate. Addressing the role of Alfven waves in these processes are the specific research topics to be addressed in this proposal. Significantly, and according to a US National Academies report in 2008, space weather also represents a potential $2 Trillion USD threat to 21st century technological infrastructure in the US alone, including impacts on the electrical power grid, satellite systems, and communications networks. As a result, the research and training proposed here is also very timely since it aligns perfectly with an increasingly important need to understand, forecast, and mitigate the impacts arising from space weather. This ensures that the fundamental science discoveries arising from the proposed research will additionally have high profile applications, with national and indeed international importance.