共查询到19条相似文献,搜索用时 140 毫秒
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研究了尘埃等离子体中尘埃声波(DAW)和尘埃离子声波(DIAW)对朗缪尔波的非线性调制。在小而有限振幅极限下,得到了朗缪尔波的包络孤立子。对于朗缪尔波与尘埃声波的非线性耦合,包络孤立子存在两个速度传播区;而对于与尘埃离子声波的耦合,只有一个传播区 相似文献
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在室温和10 Pa氩气环境中,引入平行于靶面方向的直流电场,通过改变脉冲激光能量密度烧蚀单晶硅靶,在与羽辉轴线呈不同角度的衬底上沉积纳米硅晶薄膜。利用扫描电子显微镜和拉曼散射谱对沉积样品进行分析,结果表明:随着激光能量密度的增加,位于相同角度衬底上的晶粒尺寸和面密度逐渐变大;在同一激光能量密度下,零度角处衬底上的晶粒尺寸和面密度最大,且靠近接地极板处的值比与之对称角度处略大。通过朗缪尔探针对不同能量密度下烧蚀羽辉中硅离子密度变化的诊断、结合成核区内晶粒成核生长动力学过程,对晶粒分布特性进行了分析。 相似文献
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多光子非线性Compton散射对激光等离子体中强朗缪尔湍动谱的影响 总被引:1,自引:0,他引:1
基于电子与多光子集团非线性Compton散射模型,研究了多光子非线性Compton散射对激光等离子体中强缪尔湍动谱的影响,提出了将入射光和散射光作为形成强缪尔湍动的新机制,给出了横等离激元、强朗缪尔激元和离声激元之间相互作用满足的修正方程,并进行了数值模拟.结果表明:Compton散射使横等离激元和朗缪尔激元间的碰撞频率大大增加,随着时间的演化,横等离激元和朗缪尔激元的能量由小波数区向大波数区的转移比散射前要快得多,同时产生剧烈的坍塌.坍塌后期,等离激元的强非线性作用激发出高次共振谐波,使能量从一个谐波转移到另一个谐波,形成无限高次谐波,引起波的破碎,出现由调制不稳定性控制的强朗缪尔湍动、较强的激光成丝和能量均分现象.研究结果为进一步研究强朗缪尔湍动的加速机制、反常碰撞、激光加热实验及快点火实验提供了理论支持. 相似文献
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基于电子与多光子集团非线性Compton散射模型,研究了多光子非线性Compton散射对激光等离子体中强缪尔湍动谱的影响,提出了将入射光和散射光作为形成强缪尔湍动的新机制,给出了横等离激元、强朗缪尔激元和离声激元之间相互作用满足的修正方程,并进行了数值模拟.结果表明:Compton散射使横等离激元和朗缪尔激元间的碰撞频率大大增加,随着时间的演化,横等离激元和朗缪尔激元的能量由小波数区向大波数区的转移比散射前要快得多,同时产生剧烈的坍塌.坍塌后期,等离激元的强非线性作用激发出高次共振谐波,使能量从一个谐波转移到另一个谐波,形成无限高次谐波,引起波的破碎,出现由调制不稳定性控制的强朗缪尔湍动、较强的激光成丝和能量均分现象.研究结果为进一步研究强朗缪尔湍动的加速机制、反常碰撞、激光加热实验及快点火实验提供了理论支持. 相似文献
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分析了朗缪尔探针在等离子体测量过程中的功率沉积密度,并初步计算了探针的温升,为强流离子源的探针诊断提供指导。 相似文献
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分析了朗缪尔探针在等离子体测量过程中的功率沉积密度,并初步计算了探针的温升,为强流离子源的探针诊断提供指导。 相似文献
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对长度为45 cm的短放电管螺旋波放电等离子体进行了Langmuir探针、原子发射光谱以及集成电荷耦合检测器(ICCD)检测诊断,研究螺旋波等离子体的放电特性.Langmuir探针数据显示电子密度在射频功率增加过程中出现两次大幅增长,由此确认了放电模式的转换及螺旋波放电模式的出现.发射光谱测量结果与Langmuir探针测量的电子密度数据一致,发现Ar原子和Ar离子的谱线强度与放电模式变化有着密切相关性.而通过对不同放电模式的ICCD测量,获得射频功率吸收因放电模式转变而变化的方式,认为放电模式转换时电子行为和能量传递方式也发生着变化. 相似文献
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The evolution of nonlinear Langmuir waves in the interplanetary medium is investigated by appropriately accounting for the
random density irregularities of the medium. A pair of modified Zakharov equations, which describe these waves, is solved
numerically as an initial value problem for large scale (≫ 102 km) initial pertubations. For an ion acoustic-Langmuir solitary wave, the random irregularities damp the Langmuir wave by
way of scattering and let the ion density perturbation radiate away in a few days. However an initial solitary or shock-like
Langmuir wave excites the ion density perturbations within a fraction of a second, and then itself gets damped. These effects
will strongly decelerate the collapse of large scale Langmuir waves. The possibility of detecting these processes, by means
of interplanetary scintillation, is discussed.
The authors felicitate Prof. D S Kothari on his eightieth birthday and dedicate this paper to him on this occasion. 相似文献
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Lee JS Moon SJ Yang BJ Yu J Schade U Yoshida Y Ikeda SI Noh TW 《Physical review letters》2007,98(9):097403
Optical spectra of a double-layered perovskite ruthenate Ca3Ru2O7 show a pseudogap opening around 200 cm(-1) below 50 K, which is attributable to the partial k-space gap opening due to the density wave instability. Unlike most other density wave materials, Ca3Ru2O7 has spectral weight redistributions, not near the energy gap region, but at a much higher energy region around 800 cm(-1). As a possible origin of these intriguing features, we discuss the orbital flip excitation in the density wave ground state. 相似文献
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L. N. Vyacheslavov V. S. Burmasov I. V. Kandaurov É. P. Kruglyakov O. I. Meshkov A. L. Sanin 《JETP Letters》2002,75(1):41-54
The regime of strong Langmuir turbulence characterized by the plasma nonisothermality and by the presence of an appreciable non-Maxwellian hot-electron component was experimentally studied. Turbulence was excited in the preliminary produced plasma by the relativistic electron beam. Thomson scattering of laser IR radiation served as the main diagnostic method. The spatial spectra of the Langmuir turbulence and of the attendant ion-sound turbulence were studied using Thomson collective scattering. Thomson incoherent scattering was used for studying the plasma electron distribution function and searching for the local dips of plasma density. Stark spectroscopy of turbulent microfields and the method of observation of plasma radiation at the double plasma frequency were also used. Based on the experimental data, the mechanism of Langmuir oscillation damping by plasma electrons was analyzed. The Langmuir wave conversion induced by the ion-sound turbulence is the most probable channel for energy transfer from the turbulence to plasma electrons, the low-frequency fluctuations being the direct consequence of the strong Langmuir turbulence. 相似文献
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本文给出了等离子体中由动力学理论所得到的形成强湍流的高频和低频非线性电流的表达式。根据文献[2]给出的包含有质动力、自生磁场和它们的阻尼效应的方程组,我们推广了Kono等人关于调制不稳定性的分析,得到了在各种情况下由Langmuir波或横波pump波激发的纵波和横波的增长率与参量的关系式。最后,讨论了波包的坍缩动力学问题,把非线性Schrodinger方程的坍缩讨论推广到密度和场耦合的方程组的情况。
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Tang Ting-Wei Motz H. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1977,5(4):297-300
The structure of stationary nonlinear standing Langmuir waves is examined in a self-consistent manner. A singularity for the stationary wave function is found which may cause the Langmuir waves to collapse, or expand indefinitely. 相似文献
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We report the observation of the crossover between gravity and capillary wave turbulence on the surface of mercury. The probability density functions of the turbulent wave height are found to be asymmetric and thus non-Gaussian. The surface wave height displays power-law spectra in both regimes. In the capillary region, the exponent is in fair agreement with weak turbulence theory. In the gravity region, it depends on the forcing parameters. This can be related to the finite size of the container. In addition, the scaling of those spectra with the mean energy flux is found in disagreement with weak turbulence theory for both regimes. 相似文献