原行星吸积盘中荷电尘埃颗粒的湍流输运和凝聚

Based on dusty plasma kinetic model, the present project is to study the dynamics of charging, aggregating and coupling with the gas which relevant to the structures and evolutions of protoplanetary disks. Firstly, plugging the effects of dust-collisional charging processes into the source code for dust charging in protoplanetary disks environment provided by Ivlev et al., then the charge states, distributions and fluctuations of grains will be presented. Secondly, in order to proved a possible candidate for the generation of magnetic field in the protoplanetary disks, the self-generated magnetic field of the nonlinear currents induced by the nonlinear wave-wave, wave-particle interaction in complex plasmas system consists of charged dust grains, partially ionized gas and neutral gas will be studied, then its magnitudes, scales as well as growth rates will be given through modulational instabilities analysis. Thirdly, the effects of accretion viscous and charged grains on the aerodynamics instabilities of protoplanetary disks, such as Rossby waves, secular gravitational instabilities, Jeans’ instabilities, will be investigated. Furthermore, upon the turbulent velocities associated with the vortex of aerodynamics instabilities and collisional cross-section of the grains, the aggregation growth rate under the equilibrium of turbulence collsional and electrostatic repulsion will be given, which may proved a possible route to overcome the “electrostatic barrier” or “meter barrier” for dusty coagulation.

本项目拟基于尘埃等离子体动理论，围绕与原行星吸积盘的结构和演化密切相关的尘埃颗粒的充电、聚合、与背景气体的耦合等动力学过程开展研究：基于Ivlev等的原行星吸积盘尘埃充电的源代码，进一步考虑尘埃的碰撞充电效应等，研究原行星吸积盘中尘埃颗粒的充电动力学过程，以期获得尘埃的带电量均值、分布和涨落性质等；研究荷电尘埃颗粒、部分离化气体和中性气体组成的复杂等离子体系统中由波-波、波-粒相互作用引起的非线性电流的磁场效应，分析其调制不稳定性特性，由此估算磁场强度量级和尺度以及生长速率，预期为原行星吸积盘磁场的产生提供一种可能机制；研究粘滞、尘埃颗粒的荷电效应对原行星吸积盘的流体动力学不稳定性特征的影响；在此基础上，进一步分析相关涡旋结构以及由此引起的尘埃颗粒的湍流速度及其碰撞截面，得到荷电尘埃颗粒在湍流碰撞与静电排斥作用平衡下的聚合生长规律，预期为克服尘埃聚合生长过程中遭受的静电壁垒提供可能机制。

荷电尘埃在天体结构形成和演化中扮演者重要作用，是当前的研究热点。基于尘埃等离子体动理论，研究了离子拖曳力对尘埃分子云中的金斯不稳定性和金斯脉冲模的影响，发现离子拖曳力显著增强金斯脉冲模的不稳定性，有利于尘埃凝结；研究了尘埃电荷梯度力对金斯不稳定性的影响，发现尘埃电荷梯度力增强金斯不稳定性模的增长率，使得临界金斯波长变小，有助于尘埃颗粒由于引力相互作用引起的凝聚；研究了67P/CG彗星的大气层的尘埃离声波色散特性和增长率，合理解释了观测结果；发现了一种新的磁旋转不稳定性模式，即尘埃电荷诱导的磁旋转不稳定性。进一步，根据最新研究进展，研究了由暗和亮物质组成的自引力系统中金斯不稳定性特性，发现在暗物质显著增强金斯不稳定性增长率；研究了含弱带电暗物质粒子的自引力系统中金斯不稳定性，结果表明带弱电暗物质会对自引力系统中金斯不稳定性产生强烈影响，其产生的静电相互作用力会不利于系统的引力坍塌，并发现一种类似于等离子体离声波的暗物质声波；研究了EiBI引力框架下自引力系统的金斯不稳定性，发现在高密度自引力系统中，EiBI引力场有效加剧高密度自引力系统的金斯不稳定性增长率，定性给出中子星坍塌成为黑洞的物理机制。相应的结果可为天体结构和演化机制研究提供一定的理论参考。