Charged particel transport in interstellar plasmas: Improved theory for scattering of cosmic rays in turbulent fields

星际等离子体中的带电粒子输运：湍流场中宇宙射线散射的改进理论

• 批准号: 203247539
• 负责人: Professor Dr. Frank Jenko
• 金额: --
• 依托单位: Institut für Theoretische Physik IV: Weltraum- und Astrophysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203247539?language=en
• 关键词: Charged; particel; transport; interstellar; plasmas

Cosmic rays, charged dust particles and turbulent magnetic fields are important constituents of the interstellar medium. Understanding and predicting the transport of charged particles in turbulent media is a key challenge in a number of related disciplines, ranging from magnetic confinement fusion research to astrophysics. In astrophysics, it is the scattering, acceleration and spatial diffusion of cosmic rays in interstellar magnetic fields. The purpose of this proposal is two-fold:First, we want to investigate the transport of fast particles in cosmic magnetic fields, applying scaling concepts which were developed recently in the context of tokamak physics based on the percolation theory. This can be done since although the turbulent scales are extremely different, the scattering mechanisms perpendicular to the background field are basically the same.Secondly, we want to develop an improved weak turbulence transport theory of fast charged particles in a partially turbulent magnetic field, that avoids the usually made quasilinear approximation to the particle orbits, and properly takes into account recent nonlinear improvements. Three statistical properties of the magnetic turbulence are adopted: (1) quasi-stationary turbulence, (2) the existence of a finite turbulence decorrelation time, and (3) spatially homogenous turbulence. In contrast to the scaling theory, weak turbulence transport theories often make use of the Corrsin independence hypothesis allowing one to express a fourth order correlation function in terms of the product of two second order correlation functions. Two central goals of this proposal are (1) the calculation of cosmic ray scattering rates from weak turbulence and scaling transport theories, respectively, and (2) their comparison to verify or disprove the validity of the Corrsin hypothesis for cosmic turbulent magnetic fields. The so improved transport theory will be applied to selected interstellar phenomena such as the diffusive shock acceleration of cosmic ray particles in the presence of large scale parallel spatial gradients of the guide magnetic field.

宇宙射线，带电的灰尘颗粒和湍流磁场是星际介质的重要组成部分。在许多相关学科中，了解和预测电荷颗粒在动荡的介质中的运输是一个关键挑战，从磁性限制融合研究到天体物理学。在天体物理学中，宇宙射线在星际磁场中的散射，加速度和空间扩散。该提案的目的是两个方面：首先，我们想研究宇宙磁场中快速颗粒的运输，应用了缩放概念，这些概念最近是在基于渗透理论的Tokamak物理学的背景下开发的。这可以做到这一点，因为尽管湍流尺度截然不同，但垂直于背景字段的散射机制基本上是相同的。第二，我们希望在部分湍流的磁场中发展出一种改进的快速电荷颗粒的弱湍流传输理论，避免了通常对粒子孔的粒子近似不合适的近期不合理的近似，并考虑到了最近的非单位，并考虑到了不合理的范围。采用了磁性湍流的三个统计特性：（1）准平稳湍流，（2）存在有限的湍流去相关时间，以及（3）在空间均匀的湍流。与缩放理论相反，弱的湍流转运理论通常利用Corrsin独立性假设，使一个假设可以根据两个二阶相关函数的产物来表达第四阶相关函数。该提案的两个核心目标是（1）分别从弱湍流和缩放传输理论的宇宙射线散射速率计算，以及（2）它们的比较以验证或反驳Corrsin假设对宇宙湍流磁场的有效性。如此改进的运输理论将应用于选定的星际现象，例如在有大规模的导向磁场的大规模平行空间梯度的情况下，宇宙射线颗粒的扩散冲击加速度。