Kinetic theory of linear fluctuations in magnetized and unmagnetized collisionfree plasmas

波动是所有具有有限随机等离子体粒子速度的等离子体的普遍特征。过去的研究主要集中在利用非相对论性等离子体动力学方程研究等离子体中集体弱放大/阻尼模式的涨落。提出(1)扩展非磁化等离子体的动力学线性等离子体涨落理论，特别是计算弱传播和弱放大/阻尼模式（集体和非集体模式）的相关密度和速度涨落谱；(2)利用现有的非磁化等离子体涨落理论发展磁化等离子体的线性涨落理论。这些磁化的等离子体有一个有序的磁场，在空间尺度上是均匀的，与波动的波长相比是大的。因为宇宙等离子体的高导电性。在这些系统中不存在大规模的固定电场。最重要的非磁化宇宙等离子体是在再电离开始后立即出现的部分电离星系际介质（IGM）。非周期磁波动的产生是我们提出的宇宙种子磁场产生的重要机制。相关的湍流密度和速度波动可以用来分别从色散测量、旋转测量和闪烁数据以及原子和分子谱线的湍流多普勒展宽对这些波动的强度施加观测约束。利用协变正确的等离子体动力学方程，对磁化等离子体的一般线性动力学涨落理论（不限制涨落频率）进行了系统的研究。对磁化等离子体中集体模式的广义Kirchhoff定律的推导，使我们能够定量地计算出在考虑自发发射和吸收效应的磁化等离子体中任意给定的旋向平衡等离子体粒子分布$f_{a0}(\pper, \ppa)$的集体模式下电场和磁场的涨落强度。这尤其允许对观测到的太阳风等离子体中波动的磁场强度进行定量模拟。

Fluctuations are a generic feature of all plasmas with finite random velocities of the plasma particles. Past research has concentrated predominantly on the fluctuations from collective weakly amplified/damped modes in the plasma using non-relativistic kinetic plasma equations. It is proposed to (1) extend the kinetic linear plasma fluctuation theory in unmagnetized plasmas calculating in particular the associated density and velocity fluctuation spectra of weakly propagating and weakly amplified/damped modes (collective and non-collective modes), and (2) develop the linear fluctuation theory for magnetized plasmas using the existing fluctuation theory of unmagnetized plasmas. These magnetized plasmas harbour an ordered magnetic field, uniform on spatial scales which are large compared to the wavelengths of the fluctuations. Due to the high conductivity of cosmic plasmas. no large-scale stationary electric fields exist in these systems. The most important unmagnetized cosmic plasma is the partially-ionized intergalactic medium (IGM) immediately after the reionization onset. The generation of aperiodic magnetic fluctuations in the IGM has been proposed by us as an important mechanism for the generation of cosmological seed magnetic fields. The associated turbulent density and velocity fluctuations can be used to place observational constraints on the strength of these fluctuations from dispersion measure, rotation measure and scintillation data as well as turbulent Doppler broadening of atomic and molecular lines, respectively. The general (with no restriction on the frequency of the fluctuations) kinetic linear fluctuation theory in magnetized plasmas using covariantly correct kinetic plasma equations has not been systematically studied before. The derivation of the generalized Kirchhoff laws for collective modes in magnetized plasmas allows us the quantitative calculation of the fluctuation intensities of electric and magnetic fields from collective modes for any given gyrotropic equilibrium plasma particle distribution $f_{a0}(\pper, \ppa )$ in magnetized plasmas, that take into account the effects of spontaneous emission and absorption. This permits in particular the quantitative modelling of the observed fluctuating magnetic field intensities in the solar wind plasma.