Global Solar Wind Structure: Effects of Pickup Protons

该奖项是为了响应提交给NSF/DOE基础等离子体科学与工程合作伙伴关系的一项提案，该项目将研究星际拾取质子对外日球层结构和动力学的影响。 这需要创建一个三维磁流体动力学（MHD）太阳风模型，通过整合一个模型，该模型将拾取质子作为一个单独的流体，以及一维湍流传输模型。 所采用的方法将太阳风等离子体视为三种共动物质的混合物-太阳风质子，电子和拾取质子-并且包括太阳风质子和电子以及拾取质子的单独质量和能量方程。 因此，最终的模型将考虑从拾取质子到太阳风质子的能量转移以及由于湍流耗散而产生的等离子体加热。使用倾斜偶极近似或代表性太阳磁图来规定日冕底部的边界条件将能够计算太阳风的全球结构对于太阳活动的所有阶段，达到100个天文单位，然后可以与旅行者号航天器的观测结果进行比较。 这项研究将研究太阳风在外层日光层的加热和减速、拾取离子在外层日光层物理过程中的作用、大尺度和小尺度之间的相互作用以及湍流和太阳风之间的相互作用。这项研究的结果将有助于研究其他天体物理等离子体，特别是星际介质，在那里，热等离子体和高能粒子通过波耦合，以及日冕物质抛射和宇宙射线传播，以及太阳风与当地星际介质的相互作用。 这项工作将使用和进一步开发在工业和工程应用中采用的方法，建立一个强大的跨学科的兴趣。

This award is made in response to a proposal submitted to and reviewed under the NSF/DOE Partnership in Basic Plasma Science and Engineering, joint solicitation NSF 09-596.This project will study the effects of interstellar pickup protons on the structure and dynamics of the outer heliosphere. This requires creating a three-dimensional magneto-hydrodynamic (MHD) solar wind model, by integrating a model that accounts for the pickup protons as a separate fluid, together with a one-dimensional turbulence transport model. The approach being adopted treats the solar wind plasma as a mixture of three comoving species - solar wind protons, electrons, and pickup protons - and includes separate mass and energy equations for the solar wind protons and electrons, and for the pickup protons. The final model will therefore account for the energy transfer from pickup protons to solar wind protons and for the plasma heating due to turbulent dissipation.Using the tilted-dipole approximation or representative solar magnetograms to prescribe boundary conditions at the coronal base will enable calculation of the global structure of the solar wind out to 100 astronomical units for all phases of solar activity, which can then be compared with observations from the Voyager spacecraft. The study will examine the heating and deceleration of the solar wind in the outer heliosphere, the role of pickup ions in the physical processes of the outer heliosphere, interactions between large and small scales, and the interplay between turbulence and the solar wind.The results of this research will be useful in studies of other astrophysical plasmas, in particular that of the interstellar medium, where thermal plasma and energetic particles are coupled via waves, as well as coronal mass ejections and cosmic ray propagation, and the solar wind interaction with the local interstellar medium. This work will use and further develop methods employed in industrial and engineering applications, establishing a strong cross-disciplinary interest.