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arXiv 1304.4010astro-ph.SR
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太阳低层大气中的碰撞、磁化和输运系数

Collisions, magnetization, and transport coefficients in the lower solar atmosphere

J. Vranjes, P. S. Krstic

备注：
To appear in Astron. Astrophys
发表信息：
Astron. Astrophys. 554, A22 (2013)
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摘要：

太阳低层大气是一个多成分的碰撞环境，电子和质子的碰撞频率在$10^{8}-10^{10}$ Hz范围内，可能比这两种物质的陀螺频率高得多。我们的目标是提供一个可靠的定量数据的碰撞频率，磁化强度，粘度和热导率的最重要的物种在太阳低层大气。手头有这样的数据是必不可少的任何建模，旨在描述所考虑的环境的现实属性。我们描述的高度依赖性的参数和不同的物理带电物种之间的碰撞，带电和中性物种之间。每类碰撞的主要区域都得到明确的确定。我们确定其中电子或离子或两者都未磁化的层。质子被证明是未磁化的低层大气中的一层，至少有1000公里厚，即使是一个千高斯磁场，随高度呈指数下降。在这些层中，带电物质的动力学不受磁场的影响，这一事实被用于我们的建模。粘度和导热系数计算层中的离子未磁化。我们比较粘度和摩擦，并确定每个现象的主导区域。我们提供了最可靠的定量值，最重要的参数在低太阳大气中使用的各种现象，如波，运输和磁化的粒子，和日冕物质抛射的触发机制的分析建模和数值模拟。

英文摘要：

The lower solar atmosphere is an intrinsically multi-component and collisional environment with electron and proton collision frequencies in the range $10^{8}-10^{10}$ Hz, which may be considerably higher than the gyro-frequencies for both species. We aim to provide a reliable quantitative set of data for collision frequencies, magnetization, viscosity, and thermal conductivity for the most important species in the lower solar atmosphere. Having such data at hand is essential for any modeling that is aimed at describing realistic properties of the considered environment. We describe the altitude dependence of the parameters and the different physics of collisions between charged species, and between charged and neutrals species. Regions of dominance of each type of collisions are clearly identified. We determine the layers within which either electrons or ions or both are unmagnetized. Protons are shown to be un-magnetized in the lower atmosphere in a layer that is at least 1000 km thick even for a kilo-Gauss magnetic field that decreases exponentially with altitude. In these layers the dynamics of charged species cannot be affected by the magnetic field, and this fact is used in our modeling. Viscosity and thermal conductivity coefficients are calculated for layers where ions are unmagnetized. We compare viscosity and friction and determine the regions of dominance of each of the phenomena. We provide the most reliable quantitative values for most important parameters in the lower solar atmosphere to be used in analytical modeling and numerical simulations of various phenomena such as waves, transport and magnetization of particles, and the triggering mechanism of coronal mass ejections.

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