Zaslavsky A, Krafft C, Gorbunov L, Volokitin A
Laboratoire de Physique et Technologie des Plasmas, Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 May;77(5 Pt 2):056407. doi: 10.1103/PhysRevE.77.056407. Epub 2008 May 22.
This paper is devoted to studying wave-particle interaction at "double resonance" condition, i.e., when two waves interact resonantly with the same group of charged particles. A theoretical Hamiltonian model and a symplectic numerical code are built to describe the three-dimensional interactions of wave spectra with resonant electrons in a magnetized plasma. Related simulations on the evolution of two waves of close parallel phase velocities interacting resonantly with particles' fluxes have been performed, which reveal some common features which do not depend on the kind of waves, instabilities, and particles' distributions: after the stage of linear instability, when the waves' amplitudes saturate due to particle trapping, a nonlinear process takes place which is characterized by a quasiperiodical exchange of energy between the waves, depending in particular on the value of the mismatch between the waves' resonant velocities. In order to explain such observations, a simple Hamiltonian model describing the interaction of two different waves of close resonant velocities with a periodical train of bunches of trapped particles moving synchronously has been built. It allows one to describe the nonlinear characteristics of this process as well as to estimate analytically its time scale and shows a good agreement with the numerical simulation results.
本文致力于研究“双共振”条件下的波粒相互作用，即当两列波与同一群带电粒子发生共振相互作用时的情况。构建了一个理论哈密顿模型和一个辛数值代码，以描述磁化等离子体中波谱与共振电子的三维相互作用。对具有相近平行相速度的两列波与粒子通量发生共振相互作用的演化进行了相关模拟，结果揭示了一些不依赖于波的种类、不稳定性和粒子分布的共同特征：在线性不稳定性阶段之后，当波的振幅因粒子俘获而饱和时，会发生一个非线性过程，其特征是波之间能量的准周期性交换，尤其取决于波的共振速度之间失配的值。为了解释此类观测结果，构建了一个简单的哈密顿模型，该模型描述了具有相近共振速度的两列不同波与同步移动的周期性捕获粒子束列之间的相互作用。它能够描述该过程的非线性特征，并能对其时间尺度进行解析估计，且与数值模拟结果吻合良好。
