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arXiv 2402.09737physics.plasm-ph
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使用电子等离子体对流体V态的动力学与精确控制

Dynamics and precise control of fluid V-states using an electron plasma

Giancarlo Maero, Francesca Ferrero, Massimiliano Romé

AI总结:

本研究利用Penning-Malmberg陷阱中的电子等离子体重现二维流体动力学,通过多极旋转电场生成并控制V态,结合等离子体蒸发与倾斜诱导输运调节涡度剖面,并利用自共振激发实现对Kelvin-Helmholtz模式增长的精确控制。

摘要:

电子等离子体可以在Penning-Malmberg陷阱中被约束理论上无限长的时间,这是一种线性、方位角对称的磁电静力装置,在适当条件(高磁化)下,等离子体柱的横向动力学与二维理想流体所展示的动力学同构。因此,流体动力学可以在这些系统中得到重现,并对系统参数具有极高的控制度;通过施加于陷阱扇形电极方位角补片的电势所产生的静态或时变电场(即流体应变),使得流体扰动的主动激发成为可能。一个例子是流体涡旋中的方位角速度剪切现象和Kelvin-Helmholtz(KH)不稳定性的爆发。我们提出了一项研究,其中我们利用多极旋转电场来生成V态,并观察其动力学和稳定性特性。V态是2D Kirchhoff(椭圆形)流体涡旋在非线性区向一般KH模式的推广。具体而言,我们首先讨论了如何利用组合技术(等离子体蒸发和倾斜诱导输运)来调节径向涡度剖面,这可能会对所选KH波的增长和衰减动力学产生影响。我们还研究了自共振(扫频、自锁)激发——例如,用于精确控制KH模式的增长——并讨论了应用于高阶KH波的自共振特征。

英文摘要:

An electron plasma can be confined for a theoretically infinite time in a Penning-Malmberg trap, a linear, azimuthally-symmetric magneto-electrostatic device where upon suitable conditions (high magnetization) the transverse dynamics of the plasma column is isomorphic to the one displayed by a two-dimensional ideal fluid. Fluid dynamics can thus be reproduced in these systems with a very high degree of control on the system's parameters and active excitation of fluid perturbations is made possible by the use of static or time-dependent electric fields (i.e., fluid strains) imparted by electric potentials applied to the azimuthal patches of a sectored electrode of the trap. An example is represented by azimuthal velocity shear phenomena and the insurgence of Kelvin-Helmholtz (KH) instabilities in fluid vortices. We present a study where we exploit multipolar rotating electric fields to generate V-states and observe their dynamics and stability properties. A V-state is the generalization of the 2D Kirchhoff (elliptical) fluid vortex to a generic KH mode, in the nonlinear regime. In particular, we discuss first how we can exploit a combination of techniques (plasma evaporation and tilt-induced transport) to tune the radial vorticity profile, which may have an effect on the dynamics of the growth and decay of the selected KH wave. We also investigate autoresonant (swept-frequency, self-locking) excitation - useful, e.g., for the precise control of the KH mode growth - and discuss the features of autoresonance applied to higher-order KH waves.

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