IMPLICATIONS OF A NON-MODAL LINEAR THEORY FOR THE MARGINAL STABILITY STATE AND THE DISSIPATION OF FLUCTUATIONS IN THE SOLAR WIND
IMPLICATIONS OF A NON-MODAL LINEAR THEORY FOR THE MARGINAL STABILITY STATE AND THE DISSIPATION OF FLUCTUATIONS IN THE SOLAR WIND
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DOI：
10.1088/0004-637x/715/1/260
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
E. Camporeale;T. Passot;D. Burgess
中科院分区：
文献类型：
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作者：
E. Camporeale;T. Passot;D. Burgess
具有各向异性粒子分布的磁化等离子体可能具有许多不同的动力学不稳定性。观测到的太阳风常常处于一种接近不稳定状态的状态，即处于边缘稳定状态。正态线性理论预测稳定等离子体中的波动呈指数衰减。线性化系统的非模态方法与正模态分析不同，它遵循一些摄动平衡的时间演变，因此包括瞬态效应。我们采用一种非模态方法来研究双麦克斯韦磁化等离子体的稳定性，使用朗道流体模型，我们简要地描述了它。我们证明了双麦克斯韦稳定平衡可以支持某些物理量的瞬态增长，并研究了当平衡接近其边际稳定状态时这些瞬态的行为。用非模态方法得到的结果与重新检验线性边际稳定性的概念有关。此外，我们强调了湍流波动耗散的一些方面，这表明非模态方法应包括在未来的研究中。
A magnetized plasma with anisotropic particle distributions may be unstable to a number of different kinetic instabilities. The solar wind is often observed in a state which is close to that implying instability, i.e., in a marginal stability state. Normal-mode linear theory predicts that fluctuations in a stable plasma damp exponentially. The non-modal approach for a linearized system differs from a normal-mode analysis by following the temporal evolution of some perturbed equilibria, and therefore includes transient effects. We employ a non-modal approach for studying the stability of a bi-Maxwellian magnetized plasma using the Landau fluid model, which we briefly describe. We show that bi-Maxwellian stable equilibria can support transient growth of some physical quantities, and we study how these transients behave when an equilibrium approaches its marginally stable condition. The results obtained with a non-modal approach are relevant to a re-examination of the concept of linear marginal stability. Moreover, we highlight some aspects of the dissipation of turbulent fluctuations, which suggest that the non-modal approach should be included in future studies.