标题： 通过等离子体和地球物理流体中类似$β$平面的湍流分层实现自组织 显示英文标题

标题： Self-organisation through layering of $β$-plane like turbulence in plasmas and geophysical fluids

摘要： 楼梯状结构和分层在简化的、保守位涡的等离子体和地理流体模型中被研究，通过研究湍流自组织和不同自由能产生机制（强迫或线性不稳定性）下的非线性饱和，以及标准或修改的纬向流响应。 为此，研究并比较了在标准和修改的Charney-Hasegawa-Mima方程中带有随机强迫的楼梯状结构，以及两种不同的简单不稳定性驱动模型——一个来自等离子体，另一个来自地理背景。 在这些研究中，观察到$β$平面湍流不区分纬向和非纬向扰动（即标准纬向响应），逐渐形成大尺度、椭圆状的纬向结构，这些结构逐步合并，无论它是通过强迫驱动（尽管应该足够缓慢以允许波耦合）还是通过斜压不稳定性驱动，例如使用两层模型。 相反，具有修改纬向响应的等离子体系统可以迅速形成尺寸明确的直线状、静止的射流，同样无论其驱动方式：通过随机强迫或耗散漂移不稳定性。 此外，不稳定性驱动的等离子体系统在纬向流主导状态和涡旋主导状态之间表现出相变。 在两种状态下，都可以在没有大尺度摩擦的情况下达到饱和。 显示英文摘要

摘要： Staircase formation and layering is studied in simplified, potential vorticity conserving models of plasmas and geophysical fluids, by investigating turbulent self-organisation and nonlinear saturation with different mechanisms of free energy production -- forcing or linear instability -- and with standard or modified zonal flow responses. To this end, staircase formation in both the standard and modified Charney-Hasegawa-Mima equations with stochastic forcing, along with two different simple instability driven models -- one from a plasma and from a geophysical context -- are studied and compared. In these studies, it is observed that $β$-plane turbulence that does not distinguish between zonal and non-zonal perturbations (i.e., standard zonal response) gradually forms large-scale, elliptic zonal structures that merge progressively, regardless of whether it is driven by forcing (though it should be slow enough to allow wave couplings) or by the baroclinic instability, using for example a two-layer model. Conversely, the plasma system, with its modified zonal response, can rapidly form straight, stationary jets of well-defined size, again regardless of the way it is driven: by stochastic forcing or by the dissipative drift instability. Furthermore, the instability-driven plasma system exhibits a phase transition between a zonal flow dominated state and an eddy dominated state. In both states, saturation is possible without large-scale friction.