Transport of Cosmic Rays in the Universe

研究高能粒子与磁化等离子体的相互作用在天体物理和空间科学中具有重要意义。等离子体可以在宇宙中的任何地方找到，从太阳风等离子体到星际和河外介质。带电粒子，如宇宙射线，如果移动通过等离子体，由于与湍流磁场的相互作用而经历散射。因此，粒子扩散地移动，并且粒子轨迹的简单计算不再是可能的。理解扩散过程对于理解宇宙射线的传播和扩散冲击加速是相关的。后一种机制负责宇宙粒子的产生，文献中提到，理解宇宙射线的起源是21世纪世纪物理学中最重要的问题之一。 为了探索粒子扩散，可以使用两种不同的工具。在分析理论中，人们把基本方程与不同的假设和近似结合起来。最后，人们找到了描述粒子运动的扩散系数的解析形式。这样的形式可以用于空间天气，宇宙射线传播和扩散冲击加速的研究。第二个工具是由测试粒子模拟提供的。由于20世纪末和21世纪初计算能力的提高，人们现在可以用数值方法求解单个粒子的牛顿-洛伦兹方程。通过对数千个测试粒子重复这种方法，可以从这样的模拟中获得扩散参数。这两种方法各有优缺点，但它们也是相辅相成的。我的团队使用这两种工具，分析理论，以提高我们的运输的理解，并获得可用于不同应用的公式，以及模拟，以获得高精度的扩散参数。 探索高能粒子和等离子体之间的相互作用不仅对提高我们对宇宙基本过程的理解很重要。扩散理论的结果也与空间气象研究有关。预测宇宙辐射强度对于未来的载人火星飞行任务非常重要，但也可以防止地球上的技术设备以及卫星出现故障。对于加拿大这个北方国家来说，这一点尤其重要。此外，我们工作的更基本的方面也与优化托卡马克等聚变装置有关。 拟议工作的目标是提高我们的理解如何高能粒子与天体物理等离子体相互作用，通过使用先进的分析和数值工具。我们考虑不同的应用，目的是解释测量的宇宙射线光谱和太阳系以及我们自己和外部星系的不同观测。

To explore the interaction between energetic particles and magnetized plasmas is important in astrophysics and space science. Plasmas can be found everywhere in the universe ranging from the solar wind plasma to the interstellar and extragalactic medium. Electrically charged particles, such as cosmic rays, experience scattering if moving through the plasma due to the interaction with turbulent magnetic fields. Therefore, the particles move diffusively and a simple calculation of particle trajectories is no longer possible. Understanding the diffusion process is relevant in order to understand the propagation but also diffusive shock acceleration of cosmic rays. The latter mechanism is responsible for the creation of cosmic particles and it was mentioned in the literature that to understand the origin of cosmic rays is one of the most important problems in the physics of the 21st century. In order to explore particle diffusion one can use two different tools. In analytical theory one combines fundamental equations with different assumptions and approximations. Eventually one finds analytical forms for diffusion coefficients describing the motion of the particles. Such forms can then be used in studies of space weather, cosmic ray propagation, and diffusive shock acceleration. The second tool is provided by test-particle simulations. Due to the increase of computing power in the late 20th and early 21st centuries, one can now solve the Newton-Lorentz equation for an individual particle numerically. By repeating this approach for thousands of test-particles, one can obtain diffusion parameters from such simulations. Both approaches have their advantages and disadvantages but they also complement each other. My group uses both tools, analytical theory to improve our understanding of the transport and to obtain formulas which can be used in different applications, as well as simulations to obtain diffusion parameters with high accuracy. To explore the interaction between energetic particles and plasmas is not just important for improving our understanding of fundamental processes in the universe. Diffusion theory results are also relevant for space weather investigations. To predict cosmic radiation intensities will be important for manned missions to Mars in the future but also to prevent the failure of technical equipment on Earth as well as satellites. For Canada, as a northern country, this is in particular important. Furthermore, the more fundamental aspect of our work is also relevant for optimizing fusion devices such as tokamaks. The goal of the proposed work is to improve our understanding of how energetic particles interact with astrophysical plasmas by using sophisticated analytical and numerical tools. We consider different applications with the aim to explain measured cosmic ray spectra and different observations in the solar system as well as in our own and external galaxies.