Carril Hugo A, Gidi Jorge A, Navarro Roberto E, Araneda Jaime A
Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción 4070386, Chile.
Phys Rev E. 2023 Jun;107(6-2):065203. doi: 10.1103/PhysRevE.107.065203.
The time-asymptotic state of a finite-amplitude perturbation in a collisionless and Maxwellian plasma is typically represented as a steady state of two nonlinearly superposed, counterpropagating Bernstein-Greene-Kruskal (BGK) modes. Using high-resolution Vlasov-Poisson simulations, we show that the plasma evolves self-consistently into a time-asymptotic state of multiple vortexlike structures that gradually fill the phase space and reduce filamentation. This occurs without the need for external forcing or the presence of an energetic plasma population. This finding suggests that the time-asymptotic regime of the plasma is rather akin to a nonlinear superposition of multiple BGK-like modes associated with nearly constant phase-speed waves. The electric field and the space-averaged particle distribution function exhibit a power-law broad spectrum, which is consistent with an energy cascade towards smaller scales in both position and velocity spaces.
在无碰撞且处于麦克斯韦分布的等离子体中，有限振幅微扰的时间渐近态通常表示为两个非线性叠加、反向传播的伯恩斯坦 - 格林 - 克鲁斯卡（BGK）模的稳态。通过高分辨率的弗拉索夫 - 泊松模拟，我们表明等离子体自洽地演化为多个类涡旋结构的时间渐近态，这些结构逐渐填充相空间并减少丝状化。这一过程无需外部强迫或高能等离子体群体的存在。这一发现表明，等离子体的时间渐近 regime 相当类似于与近恒定相速波相关的多个类 BGK 模的非线性叠加。电场和空间平均粒子分布函数呈现幂律宽谱，这与在位置和速度空间中向更小尺度的能量级联相一致。
