Large-amplitude current-driven plasma instabilities, which can transition to the Buneman instability, were observed in one-dimensional simulations to generate high-energy back-streaming ions. We investigate the saturation of multi-dimensional plasma instabilities and its effects on energetic ion formation. Such ions directly impact spacecraft thruster lifetimes and are associated with magnetic reconnection and cosmic ray inception. An Eulerian Vlasov–Poisson solver employing the grid-based direct kinetic method is used to study the growth and saturation of 2D2V collisionless, electrostatic current-driven instabilities spanning two dimensions each in the configuration (D) and velocity (V) spaces supporting ion and electron phase-space transport. Four stages characterise the electric potential evolution in such instabilities: linear modal growth, harmonic growth, accelerated growth via quasi-linear mechanisms alongside nonlinear fill-in and saturated turbulence. Its transition and isotropisation process bears considerable similarities to the development of hydrodynamic turbulence. While a tendency to isotropy is observed in the plasma waves, followed by electron and then ion phase spaces after several ion-acoustic periods, the formation of energetic back-streaming ions is more limited in the 2D2V than in the 1D1V simulations. Plasma waves formed by two-dimensional electrostatic kinetic instabilities can propagate in the direction perpendicular to the net electron drift. Thus, large-amplitude multi-dimensional waves generate high-energy transverse-streaming ions and eventually limit energetic backward-streaming ions along the longitudinal direction. The multi-dimensional study sheds light on interactions between longitudinal and transverse electrostatic plasma instabilities, as well as fundamental characteristics of the inception and sustenance of unmagnetised plasma turbulence.

中文翻译：

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多维和能量交换对静电电流驱动等离子体不稳定性和湍流的影响

在一维模拟中观察到大振幅电流驱动的等离子体不稳定性，这种不稳定性可以转变为布尼曼不稳定性，以产生高能回流离子。我们研究了多维等离子体不稳定性的饱和度及其对高能离子形成的影响。这些离子直接影响航天器推进器的寿命，并与磁重联和宇宙射线起始有关。采用基于网格的直接动力学方法的欧拉 Vlasov-Poisson 求解器用于研究 2D2V 无碰撞、静电电流驱动的不稳定性的增长和饱和，该不稳定性跨越两个维度，分别在支持离子和速度的空间 (D) 和速度 (V) 空间中。电子相空间传输。四个阶段描述了这种不稳定性中的电势演化：线性模态增长、谐波增长、通过准线性机制以及非线性填充和饱和湍流加速增长。其转变和各向同性过程与流体动力湍流的发展具有相当大的相似性。虽然在等离子体波中观察到各向同性的趋势，然后是电子，然后是几个离子声周期后的离子相空间，但在 2D2V 模拟中，高能回流离子的形成比 1D1V 模拟中更受到限制。由二维静电动力学不稳定性形成的等离子体波可以沿垂直于净电子漂移的方向传播。因此，大振幅多维波产生高能横向流离子，并最终限制沿纵向的高能反向流离子。多维研究揭示了纵向和横向静电等离子体不稳定性之间的相互作用，以及非磁化等离子体湍流的起始和维持的基本特征。