Chaotic Process in Plasma Wave System

为了阐明静电等离子体波的混沌过程，我们研究了电子束等离子体系统中的混沌现象，该系统是利用双等离子体在驱动等离子体和目标等离子体之间施加直流电势来实现的。利用频谱分析仪对观测到的不稳定波进行频谱测量。此外，通过干涉法测量波型，得到了试验波的频散关系。主要研究结果如下：(1)将电子束注入靶等离子体激发的不稳定波(130-200 MHz)。(2)驻波是在电子束注入形成的势垒之间激发的。(3)随着密度的增加，系统出现1/2、1/4和1/3(亚谐)分叉。(4)从不稳定波的时间序列估计关联维度，证实系统处于混沌状态。

To clarify chaotic process of electrostatic plasma waves we studied chaotic phenomena in an electron beam plasma system which was realized by applying dc potential between the driver plasma and target plasma using the Double plasma. Frequency spectrum of observed unstable waves was measured with the spectrum analyzer. Furthermore, the dispersion relation of test waves was obtained by measuring wave patterns by the interference method. Main results are as follows :(1) Injecting an electron beam into the target plasma excited unstable waves (130-200 MHz). These waves, which are the electron beam mode, were found to consist of standing waves.(2) The standing waves were excited between a potential well formed by the injection of the electron beam.(3) When the density was increased, bifurcation of 1/2,1/4, and 1/3 (subharmonics) was observed.(4) Estimating the correlation dimension from time series of the unstable waves, the present system was confirmed to be in a chaotic state.