标题： 日球层中星际尘埃颗粒的动力学荷电 显示英文标题

标题： Dynamical charging of interstellar dust particles in the heliosphere

摘要： 星际尘埃（ISD）颗粒由于太阳与局部星际云的相对运动而穿透太阳系。 在进入日球层之前，它们会穿过日球层界面——即太阳风与星际等离子体相互作用的区域。 在该界面内，尘粒的尺寸分布和数密度会被显著改变。 这种改变取决于尘粒沿其轨迹的荷电情况。 本文中，我们展示了穿过日球层界面的ISD粒子荷电的建模结果。 在日球层条件下，负责荷电的主要物理过程包括初级等离子体粒子的附着、次级电子发射、光电发射以及宇宙射线电子的影响。 我们考虑了两种计算ISD粒子电荷的方法：（1）经典的稳态假设，即电荷仅依赖于局部等离子体和辐射条件；（2）沿粒子轨迹的动力学计算。 我们证明，在模拟相对较大的ISD颗粒（半径为100纳米及以上）穿越日球层的轨迹和数密度分布时，稳态假设相当合理。 估算表明，这些尺寸的ISD颗粒在从LISM过渡到日球层后不到0.25年（距离约1天文单位）即可达到平衡。 对于小颗粒（半径为10纳米），电荷的动力学计算会影响轨迹并显著修改数密度。 在动态变化电荷的情况下，尘埃密度聚集分布在日球层边界附近的一个更拉长的区域内，与使用稳态电荷近似相比。 显示英文摘要

摘要： Interstellar dust (ISD) particles penetrate the solar system due to the relative motion of the Sun and the local interstellar cloud. Before entering the heliosphere, they pass through the heliospheric interface - the region of the solar wind interaction with the interstellar plasma. The size distribution and number density of dust grains are modified in the interface essentially. The modification depends on the charging of the dust particles along their trajectories. In this paper, we present modeling results of the charging of ISD particles passing through the heliospheric interface. The main physical processes responsible for the charging within the heliospheric conditions are the sticking of primary plasma particles, secondary electron emission, photoemission, and the effects of cosmic ray electrons. We consider two methods to calculate the electric charge of ISD particles based on (1) the classic steady-state assumption that the charge depends only on local plasma and radiation conditions and (2) the dynamical computation of charge along the particle trajectory. We demonstrate that the steady-state assumption is quite justified to model trajectories and number density distributions of relatively big ISD grains (radius of 100 nm and larger) penetrating the heliosphere. The estimates show that ISD grains of these sizes require less than 0.25 years (distance of ~ 1 au) after transition from the LISM into the heliosphere to reach an equilibrium. For small particles (radius of 10 nm), the dynamical computation of charge influences the trajectories and modifies the number density substantially. The dust density accumulations are distributed within a more elongated region along the heliopause in case of dynamically changed charge as compared with the use of a steady-state charge approximation.