Ghizzo Alain, Del Sarto Daniele, Betar Homam
Institut Jean Lamour, UMR 7198, Université de Lorraine, BP 70239 54506 Vandoeuvre les Nancy cedex, France.
Mécanique et Modelisation, Procédés Propres, UMR 7340 CNRS, Université de Aix-Marseille, 38 rue Joliot-Curie, 13451 Marseille, France.
Phys Rev Lett. 2023 Jul 21;131(3):035101. doi: 10.1103/PhysRevLett.131.035101.
We perform high resolution kinetic simulations of interpenetrating plasma beams. This configuration is unstable to both Weibel-type and two-stream instabilities, which are known to linearly induce a growth of the magnetic and electrostatic energy, respectively, at the expenses of the kinetic energy. "Oblique modes" are further beam-plasma instabilities, which linearly combine the features of the former two. Here we show the possibility of a reversal of the energy flow associated to these beam-plasma instabilities, when secondary propagating oblique modes are excited. This rapid conversion from magnetic to kinetic energy (i.e., kinetic heating), differs from the standard magnetic reconnection scenario and is induced by the reinforcement of the filamentation process of the distribution function in the phase space. This phenomenon-likely of general interest to collisionless dissipation processes in plasmas-can be understood in terms of mode synchronization: the coupling of oblique modes at disparate spatial scales leads to the appearance of synchronized "filamented" modes, which act on the global dynamics of the plasma via kinetic heating, collisionless dissipation, and turbulence.
我们对互穿等离子体束进行了高分辨率动力学模拟。这种构型对韦贝尔型和双流不稳定性均不稳定，已知这两种不稳定性分别以动能为代价线性地导致磁能和静电能的增长。“斜模”是进一步的束 - 等离子体不稳定性，它线性地结合了前两者的特征。在此我们表明，当激发二次传播斜模时，与这些束 - 等离子体不稳定性相关的能量流有可能发生反转。这种从磁能到动能的快速转换（即动能加热）不同于标准的磁重联情形，并且是由相空间中分布函数的丝状化过程的增强所引起的。这种现象——可能对等离子体中的无碰撞耗散过程具有普遍意义——可以从模式同步的角度来理解：不同空间尺度的斜模耦合导致出现同步的“丝状”模式，这些模式通过动能加热、无碰撞耗散和湍流作用于等离子体的整体动力学。
