The Role of Alfven Wave Energy Transport in Geospace Dynamics

点击翻译按钮获取中文摘要

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.