Turbulence Transport in Sub-Alfvenic and Subsonic Astrophysical Plasma Flows

通过拟议的为期3年的研究项目，我们打算加强德国波鸿鲁尔大学和新西兰汉密尔顿怀卡托大学之间的成功协作，这一协作最近是在DFG关于日光层和天体球层的等离子体流体和湍流传输耦合模型专题的1年期专项资金框架内启动的。拟议研究项目的主要目标是：(1)对太阳风和其他恒星风的外部亚阿尔文和亚音速区域内的湍流传输进行定量评估，以及(2)对由此产生的高能粒子传输进行定量研究。因此，该项目的主要目标是回答关于湍流演化以及传输过程和相应的传输方程的以下三个关键科学问题：(1)如何在多分量模型框架内定量描述部分亚阿尔文和亚音速内日鞘(太阳风终止激波和太阳顶层之间)和恒星星鞘(恒星风终止激波和弓形激波之间)中的湍流传输？(2)内日鞘和恒星天体鞘中的湍流演化如何影响宇宙线传输参数的时空变化？和(3)当使用新的可压缩湍流模型来获得传输参数时，宇宙线传输方程的解是什么？通过实现这一及时计划的目标，我们不仅将用新的三分量描述来补充急需的湍流演化模型，这将首次允许同时和自洽地处理准二维、波状以及压缩涨落，而且我们还将建立一个显著改进的概念框架，用于模拟高能粒子在内日鞘和恒星天体鞘中的传输条件。鉴于旅行者号航天器最近和正在进行的在日鞘中进行的现场测量，以及天体球体对于宇宙线加速和宇宙线各向异性的潜在重要性，这两个运输环境在当代引起了太阳物理学和天体物理学的高度关注。

With the proposed 3-year research project we intend to intensify the successful collaboration between the Ruhr-Universität of Bochum, Germany, and the University of Waikato, Hamilton, New Zealand, that was recently initiated within the framework of a dedicated 1-year DFG funding on the topic of coupled plasma fluid and turbulence transport modelling of the heliosphere and of astrospheres. The main goals of the proposed research project are (i) a quantitative assessment of the transport of turbulence in the outer sub-Alfvenic and subsonic regimes of the solar wind and other stellar winds, and (ii) a quantitative study of the resulting transport of energetic particles. Consequently, the primary objective of the project is the answering of the following three scientific key questions regarding the turbulence evolution as well as the transport processes and the corresponding transport equation:(1) How can the transport of turbulence in the partially sub-Alfvenic and subsonic inner heliosheath (between the solar wind termination shock and the heliopause) and in stellar astrosheaths (between the stellar wind termination shocks and the bow shocks) be described quantitatively within the framework of a multi-component model?,(2) How does the turbulence evolution in the inner heliosheath and in stellar astrosheaths influence the spatial and temporal variation of the transport parameters of cosmic rays?, and (3) What are the solutions of the cosmic ray transport equation when using the new compressible turbulence model to obtain the transport parameters?By attaining the goals of this timely project we will not only supplement the much needed models of turbulence evolution with a new, three-component description that, for the first time, will allow for a simultaneous and self-consistent treatment of quasi-twodimensional, wave-like, as well as compressive fluctuations, but we will also establish a significantly improved conceptual framework for the modelling of the transport conditions of energetic particles in both the inner heliosheath and in stellar astrosheaths. In view of the recent, and ongoing, in-situ measurements made in the heliosheath by the Voyager spacecraft and the potential importance of astrospheres for cosmic ray acceleration and cosmic ray anisotropies, both transport environments are of high contemporary interest for the helio- and astrophysics communities.