Nongyrotropic particle distributions in space plasmas
Nongyrotropic particle distributions in space plasmas
复制标题
空间等离子体中的非自旋粒子分布
DOI：
10.1007/s00585-999-0613-4
复制
发表时间：
1999
影响因子：
1.9
通讯作者：
A. Brinca
中科院分区：
文献类型：
--
作者：
U. Motschmann;K. Glassmeier;A. Brinca
在非平稳、强非均匀或开放等离子体中，粒子轨道相当复杂。如果非平稳时间尺度小于旋转周期，如果非均匀性尺度小于旋转半径，即在磁等离子体边界处，或者等离子体在相空间中有源和汇，则出现非涡旋分布函数。在线性色散理论的框架下研究了这种等离子体结构的稳定性。在开放等离子体中，非涡旋性驱动不稳定波平行和垂直于背景磁场，而在涡旋性限制下，等离子体是稳定的。在非静止等离子体中，非涡旋性只驱动垂直的不稳定波。时间调制将种子模式与其旁瓣耦合，从而使不稳定波的增长变得更加困难。作为非均匀等离子体的一个例子，讨论了磁性半空间。在具有热质子陀螺半径厚度的层中，形成非涡旋分布，可激发不稳定的平行和垂直传播波。关键字。行星际物理（等离子体波和湍流）·电离层（等离子体波和不稳定性）·磁层物理（等离子体波和不稳定性）
In nonstationary, strong inhomogeneous or open plasmas particle orbits are rather complicated. If the nonstationary time scale is smaller than the gyration period, if the inhomogeneity scale is smaller than the gyration radius, i.e. at magnetic plasma boundaries, or if the plasma has sources and sinks in phase space, then nongyrotropic distribution functions occur. The stability of such plasma configurations is studied in the framework of linear dispersion theory. In an open plasma nongyrotropy drives unstable waves parallel and perpendicular to the background magnetic field, whereas in the gyrotropic limit the plasma is stable. In nonstationary plasmas nongyrotropy drives perpendicular unstable waves only. Temporal modulation couples a seed mode with its side lobes and thus it renders unstable wave growth more difficult. As an example of an inhomogeneous plasma a magnetic halfspace is discussed. In a layer with thickness of the thermal proton gyroradius a nongyrotropic distribution is formed which may excite unstable parallel and perpendicular propagating waves.Key words.Interplanetary physics (plasma waves and turbulence) · Ionosphere (plasma waves and instabilities) · Magnetospheric physics (plasma waves and instabilities)