Plasma electron-hole kinematics: momentum conservation

We analyse the kinematic properties of a plasma electron hole: a non-linear self-sustained localized positive electric potential perturbation, trapping electrons, that behaves as a coherent entity. When a hole accelerates or grows in depth, ion and electron plasma momentum is changed both within the hole and outside it, by an energization process we call jetting. We present a comprehensive analytic calculation of the momentum changes of an isolated general one-dimensional hole. The conservation of the total momentum gives the hole's kinematics, determining its velocity evolution. Our results explain many features of the behavior of hole speed observed in numerical simulations, including self-acceleration at formation, and hole pushing and trapping by ion streams.

我们对等离子体电子空穴（plasma electron hole）的运动学特性展开分析：该结构是一种非线性、自维持的局域化正电势扰动，能够俘获电子，并作为相干实体存在。当空穴加速或深度增大时，等离子体中的离子与电子的动量会在空穴内部及外部均发生变化，该变化由我们命名为“喷射”的能量激发过程所驱动。我们针对孤立的通用一维空穴的动量变化开展了全面的解析计算。总动量守恒给出了空穴的运动学行为，进而决定其速度演化过程。我们的研究结果解释了数值模拟中观测到的空穴速度演化的诸多特征，包括其形成过程中的自加速现象，以及离子流对空穴的推挤与俘获效应。