论文标题
参数不稳定性在湍流产生和质子加热中的作用：平行传播alfvén波的混合模拟
The role of parametric instabilities in turbulence generation and proton heating: Hybrid simulations of parallel propagating Alfvén waves
论文作者
论文摘要
大幅度的Alfvén波往往与参数不稳定不稳定，这会导致初始波的衰减过程，这取决于波动的振幅和等离子体β的幅度。相对于女儿波的平均磁场的传播角在确定衰减的类型中起着重要作用。在本文中，我们通过多维混合模拟来重新审视这个问题。特别是，我们通过研究不稳定性的饱和度及不稳定性的饱和机制及其最终的非线性状态，以针对不同的波幅度和等离子体β条件进行研究。与一维模拟相比，抑制血浆β值的衰减不稳定性被抑制了衰减不稳定性，我们发现多维中的衰减过程通过细丝/磁性衰减不稳定性在血浆β的巨大值下持续存在。通常，衰减过程是发展垂直湍流级联反应并增强平均场对齐波粒子相互作用的触发。我们确实发现，饱和状态的特征是湍流的等离子体，该血浆在Alfvén速度下显示了野外对准的光束，并且我们归因于Landau共振和相位空间中的螺距角度散射的温度升高。
Large amplitude Alfvén waves tend to be unstable to parametric instabilities which result in a decay process of the initial wave into different daughter waves depending upon the amplitude of the fluctuations and the plasma beta. The propagation angle with respect to the mean magnetic field of the daughter waves plays an important role in determining the type of decay. In this paper, we revisit this problem by means of multi-dimensional hybrid simulations. In particular, we study the decay and the subsequent nonlinear evolution of large-amplitude Alfvén waves by investigating the saturation mechanism of the instability and its final nonlinear state reached for different wave amplitudes and plasma beta conditions. As opposed to one-dimensional simulations where the Decay instability is suppressed for increasing plasma beta values, we find that the decay process in multi-dimensions persists at large values of the plasma beta via the filamentation/magnetosonic decay instabilities. In general, the decay process acts as a trigger both to develop a perpendicular turbulent cascade and to enhance mean field-aligned wave-particle interactions. We find indeed that the saturated state is characterized by a turbulent plasma displaying a field-aligned beam at the Alfvén speed and increased temperatures that we ascribe to the Landau resonance and pitch angle scattering in phase space.
