The nonlinear evolution of the ion–ion streaming instability (IISI) is studied using numerical techniques novel to this problem that afford direct insight into the evolution of the particle distributions of each species. During the linear phase of the instability, we demonstrate quantitative agreement with linear kinetic theory. Subsequently, the electrostatic field generated by the IISI causes ring-like velocity distributions of ions to form that are both heated and slowed to varying degrees relative to their initial flows. Due to variation in the trapping conditions for ion species of differing charge-to-mass ratio, when flows of multiple species interact, the nonlinear evolution of each species can be starkly different: we show a case where a lighter ion species is completely stopped by a heavier ion species via the IISI alone (i.e., without collisions) and, for the first time, demonstrate how the IISI can introduce a relative flow between ion species that initially have the same flow velocities, thereby separating them.

中文翻译：

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单离子和多离子物种等离子体中离子-离子流不稳定性的非线性动力学模拟研究

使用对该问题新颖的数值技术研究了离子-离子流不稳定性（IISI）的非线性演化，这些数值技术可直接了解每种物质的粒子分布的演化。在不稳定的线性阶段，我们证明了与线性动力学理论的定量一致性。随后，由IISI产生的静电场导致形成环状的离子速度分布，这些离子相对于其初始流量都被加热并减慢了不同的程度。由于不同质荷比的离子物质的俘获条件不同，当多种物质的流动相互作用时，每种物质的非线性演化可能截然不同：我们展示了一种情况，其中较轻的离子物质完全被仅通过IISI获得较重的离子种类（即，