等离子体中非线性朗谬尔波的哈密顿描述

HAMILTONIAN DESCRIPTION OF NONLINEAR LANGMUIR WAVES IN A PLASMA

研究了在双离子 (H+ 、O+ )成份等离子体中的非线性朗谬尔波的特性。从流体方程出发 ,考虑低频离子运动的完全非线性和双极势的色散 ,得到了描述高频电场缓变振幅与低频势扰动的耦合方程组。利用哈密顿方法 ,在小振幅情况下 ,对方程组解耦合 ;利用Sagdeev势方法 ,对孤立波的性状进行了讨论。结果表明 ,双离子成份等离子体中双极势的孤立子的幅度相对电子 离子等离子体的双极势孤立子的幅度要大 ,而相应的高频电场强度的幅度相对要小 ,相应的孤立子的速度传播区也较小。

The nonlinear Langmuir waves in a two ion component plasma have been studied.Taking into account the fully nonlinear response of the low frequency ion motion and the dispersion of the bipolar potential,a set of coupled equations,describing a slow change in the amplitude of the high frequency Langmuir wave and the low frequency perturbation of the bipolar potential has been derived from the two component fluid model.Using the Hamiltionian method,this set of coupled equations was decoupled in the case of small amplitude.Using Sagdeev potential,the characteristic of the solitary wave has been discussed.Results show that the amplitude for the bipolar potential in a two ion component plasma is larger than that in an electron ion plasma while the intensity amplitude for the high frequency electrical field and the propagation region for the solitary velocity are smaller than those in an electron ion plasma.