Ion heating and flow driven by an Instability found in Plasma Couette Flow

磁化Taylor-Couette流中噪声维持的对流不稳定性

Noise-Sustained Convective Instability in a Magnetized Taylor-Couette Flow

对有限长圆柱内磁化泰勒-库埃特流的螺旋磁旋转不稳定性进行了数值研究。一个遥远的上游绝缘边界示出完全稳定的对流不稳定，同时降低绝对不稳定的增长率。高度越大，减少越不严重。在适当地模拟边界条件后，实验中观察到的波型原来是噪声持续的对流不稳定。当不稳定的Ekman层和Stewartson层产生的噪声源被切断后，在模拟中观察到缓慢衰减的惯性振荡。我们得出的结论是，迄今为止完成的实验尚未达到绝对不稳定的制度。

等离子体库埃特实验中磁旋转不稳定性的观测前景

Prospects for observing the magnetorotational instability in the Plasma Couette Experiment

许多天体物理盘，如原行星盘，处于非理想的等离子体磁流体动力学（MHD）效应可以显著影响磁旋转不稳定性（MRI）行为的区域。讨论了在等离子体库埃特实验（PCX）中研究这些效应的可能性。不可压缩的，耗散的全局稳定性分析，包括等离子体特定的两种流体的影响和中性碰撞，这是本质上缺乏在液态金属实验中的泰勒-库埃特流（TCFs）的分析。结果表明，与边界驱动的流量，离子中性碰撞拖曳体力显着影响的方位角速度分布，从而限制了MRI不存在的制度的流量。电驱动流（EDF）被提出作为一种替代的体力流驱动，其中MRI可以在更容易实现的等离子体参数不稳定。描述了达到MRI相关参数空间和必要硬件升级的场景。

Stability and instability of hydromagnetic Taylor-Couette flows

Decades ago S. Lundquist, S. Chandrasekhar, P.H. Roberts and R. J.~Tayler first posed questions about the stability of Taylor-Couette flows of conducting material under the influence of large-scale magnetic fields. These and many new questions can now be answered numerically where the nonlinear simulations even provide the instability-induced values of several transport coefficients. The cylindrical containers are axially unbounded and penetrated by magnetic background fields with axial and/or azimuthal components. The influence of the magnetic Prandtl number $Pm$ on the onset of the instabili…

Quasi-two-dimensional nonlinear evolution of helical magnetorotational instability in a magnetized Taylor-Couette flow

Magnetorotational instability (MRI) is one of the fundamental processes in astrophysics, driving angular momentum transport and mass accretion in a wide variety of cosmic objects. Despite much theoretical/numerical and experimental efforts over the last decades, its saturation mechanism and amplitude, which sets the angular momentum transport rate, remains not well understood, especially in the limit of high resistivity, or small magnetic Prandtl numbers typical to interiors (dead zones) of protoplanetary disks, liquid cores of planets and liquid metals in laboratory. Using direct numerical si…

Short wavelength local instabilities of a circular Couette flow with radial temperature gradient

We perform a linearized local stability analysis for short-wavelength perturbations of a circular Couette flow with the radial temperature gradient. Axisymmetric and nonaxisymmetric perturbations are considered and both the thermal diffusivity and the kinematic viscosity of the fluid are taken into account. The effect of the asymmetry of the heating both on the centrifugally unstable flows and on the onset of the instabilities of the centrifugally stable flows, including the flow with the Keplerian shear profile, is thoroughly investigated. It is found that the inward temperature gradient dest…

Stochastic ion and electron heating on drift instabilities at the bow shock

The analysis of the wave content inside a perpendicular bow shock indicates that heating of ions is related to the Lower-Hybrid-Drift (LHD) instability, and heating of electrons to the Electron-Cyclotron-Drift (ECD) instability. Both processes represent stochastic acceleration caused by the electric field gradients on the electron gyroradius scales, produced by the two instabilities. Stochastic heating is a single particle mechanism where large gradients break adiabatic invariants and expose particles to direct acceleration by the DC- and wave-fields. The acceleration is controlled by function…