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arXiv 1009.1302physics.plasm-ph
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量子等离子体中的非线性波-波相互作用

Nonlinear wave-wave interactions in quantum plasmas

A. P. Misra, P. K. Shukla

摘要:

等离子体中的波-波相互作用是16世纪以来的重要研究课题。在现代等离子体物理中,由高频朗缪尔波和低频离子声波耦合而形成的朗缪尔孤子是湍流背景下最有趣的现象之一。此外,量子等离子体,这是无处不在的超小型电子设备,微机械系统以及在密集的天体物理环境中是当前的研究课题。基于对量子等离子体的研究兴趣,本文从理论上研究了一维量子Zakharov方程(QZEs)所描述的量子朗缪尔波(QLWs)和量子离子声波(QIAWs)的非线性相互作用.结果表明,当线性模的激发长度尺度大于最不稳定模的激发长度尺度时,系统将发生时空混沌的转变。然而,在量子隧穿效应的存在下,这样的长度尺度将更大(与经典的长度尺度相比)。后者诱导强烈的QIAW辐射,导致模式之间的碰撞和融合的发生在比经典的情况下更早的时间。此外,数值模拟的QZEs显示,许多孤立的模式可以激发和饱和通过调制不稳定性(MI)的不稳定的谐波模式。在较长的时间内,由于强QIAW辐射以及随机运动中的碰撞和融合,这些孤子出现在STC状态。因此,系统中的能量被强烈地重新分配,这可能会开启量子等离子体中朗缪尔湍流的开始。

英文摘要:

Wave-wave interaction in plasmas is a topic of important research since the 16th century. The formation of Langmuir solitons through the coupling of high-frequency (hf) Langmuir and low-frequency (lf) ion-acoustic waves, is one of the most interesting features in the context of turbulence in modern plasma physics. Moreover, quantum plasmas, which are ubiquitous in ultrasmall electronic devices, micromechanical systems as well as in dense astrophysical environments are a topic of current research. In the light of notable interests in such quantum plasmas, we present here a theoretical investigation on the nonlinear interaction of quantum Langmuir waves (QLWs) and quantum ion-acoustic waves (QIAWs), which are governed by the one-dimensional quantum Zakharov equations (QZEs). It is shown that a transition to spatiotemporal chaos (STC) occurs when the length scale of excitation of linear modes is larger than that of the most unstable ones. Such length scale is, however, to be larger (compared to the classical one) in presence of the quantum tunneling effect. The latter induces strong QIAW emission leading to the occurrence of collision and fusion among the patterns at an earlier time than the classical case. Moreover, numerical simulation of the QZEs reveals that many solitary patterns can be excited and saturated through the modulational instability (MI) of unstable harmonic modes. In a longer time, these solitons are seen to appear in the state of STC due to strong QIAW emission as well as by the collision and fusion in stochastic motion. The energy in the system is thus strongly redistributed, which may switch on the onset of Langmuir turbulence in quantum plasmas.

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