共查询到20条相似文献,搜索用时 156 毫秒
1.
由伏拉索夫方程和费米分布函数的相对论性修正形式推导出相对论性正负电子对等离子体中横波的色散方程,对等离子体中的横波进行解析研究,得到长波支和短波支的色散关系。从解析的色散曲线发现了与Mikhailovskii在极端相对论性情况下对于电子-离子等离子体中色散关系研究相类似的结果:在极端相对论性等离子体中横波的解析色散曲线具有不连续性。基于解析色散曲线的不连续性,进而采用数值计算的方法求解了完整的等离子体色散方程,得到其数值解,数值色散曲线可将解析上的长波和短波衔接起来,使其成为一条完整的色散曲线。 相似文献
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研究了无磁化、无碰撞、各向同性相对论q分布正负电子对等离子体横振荡色散关系,通过理论推导得到与非广延参数q有关的色散方程。从该色散方程出发,得到极端相对论情况下长波支和短波支下等离子体横振荡色散关系解析解,为了得到完整的色散曲线,对色散方程进行数值计算,在极端相对论情况下数值结果与解析结果在长波支和短波支下完全吻合。研究发现相对论q分布下色散关系与非广延参数q和温度有关,当q1时,则渐进结果与经典统计下的一致。 相似文献
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本文对各向同性极端相对论快电子呈幂律分布等离子体中横振荡色散关系进行了解析和数值研究.得到长波支和短波支色散关系的解析表达式.由于解析近似对波数的限制,无法得到全波数空间色散曲线,因此对色散方程进行了数值求解.研究表明,在满足长波支和短波支条件时,解析色散曲线与数值色散曲线完全符合.此外,利用多项式回归的方法对数值结果进行拟合,得到不同参数下快电子分布等离子体横振荡色散关系近似表达式,该结果为进一步研究快电子分布等离子体的性质提供了重要的理论依据.
关键词:
相对论性等离子体
快电子分布
色散关系
数值计算 相似文献
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由相对论回旋动力论方程出发,推导出弱相对论非均匀等离子体的普遍色散关系。该色散关系可以适用于任意的磁场位形和任意有限频率。在色散关系中把带有速度平方项分母的奇异积分用等离子体漂移色散函数解析地表示出来,从而可以把这一结果用于较系统地解析或半解析地研究由弱相对论效应,磁场的梯度和曲率,回旋频移等共振驱动的各种微观不稳定性的性质。由于推导时考虑了温度各向异性的麦氏分布函数,因而可以直接推广并应用到损失锥非平衡分布的情况。文中还演示了它在低杂漂移不稳定性研究中的应用。由该色散关系出发,可以简捷并系统地得到Drake等人的结果。
关键词: 相似文献
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本文在两种碰撞模型(BGK模型和LB模型)下,计算了碰撞对等离子体色散方程的影响。碰撞的主要作用是使色散函数Z(ξ)变为广义色散函数W(ξ,ν)。分析比较了两种模型下广义色散函数的性质。讨论了碰撞对低频漂移波(局域模)和离声波稳定性的影响。分析表明,LB模型不仅在物理上更为合理,而且在计算及表达形式上也比BGK模型更为简明。
关键词: 相似文献
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当同时使用离子(或电子)回旋及中性束注入方式加热等离子体时,高能量粒子的能量分布函数一般应为尾部隆起(简称尾隆)分布。这种具有正能量梯度区域的分布函数更容易激发不稳定性,同时由于分布函数尾部隆起,在色散关系中引入了新的色散函数。主要研究了这种新色散函数的计算方法,结果表明:色散函数实部是关于原点对称的奇函数;而虚部则是关于纵轴对称的偶函数。色散函数的实部有2~4 个极值点且极值点的位置与尾隆分布函数的能量梯度Δ 有关、虚部有1~3 个极值点但极值点位置与Δ 无关。当其宗量趋于无穷大时,色散函数的值趋于零。当尾隆分布趋近于麦克斯韦分布时,用该方法计算的结果与色散函数表中给出的结果非常吻合。 相似文献
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通过理论研究与数值计算,不均匀等离子体中Langmuir波与电磁波的相互作用及其线性模式转换规律得到了充分的展示.导出了不均匀等离子体中的电磁色散关系,研究了入射电磁波或Langmuir波在通过不均匀等离子体的过程中发生转换的物理过程,以及波的传播矢量随空间坐标变化的关系,并对电磁波与Langmuir波相互作用的机理进行了讨论.研究结果对密度梯度所驱动的等离子体波产生电磁辐射的研究具有重要意义.
关键词:
电磁波
Langmuir波
不均匀等离子体
线性模式转换 相似文献
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H. Steudel 《Annalen der Physik》1975,487(6):445-455
A method developed recently by the author to derive a continuum of conservation laws by Noether's theorem from the so-called extended Bäcklund transformations is applied to the KORTEWEG -DE VRIES equation that describes various nonlinear dispersive wave phenomena in hydrodynamics, plasma physics and solid state physics. Further applications of Noether's theorem concerning this equation are given. It is shown that the Galilean transformation in the present case has an analogous function as Lie's transformation has with respect to the sine-Gordon equation. 相似文献
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Mohammed K. Elboree 《理论物理通讯》2015,64(4):379-390
In this paper, we investigate the traveling wave solutions for the nonlinear dispersive equation, Korteweg-de Vries Zakharov-Kuznetsov (KdV-ZK) equation and complex coupled KdV system by using extended simplest equation method, and then derive the hyperbolic function solutions include soliton solutions, trigonometric function solutions include periodic solutions with special values for double parameters and rational solutions. The properties of such solutions are shown by figures. The results show that this method is an effective and a powerful tool for handling the solutions of nonlinear partial differential equations (NLEEs) in mathematical physics. 相似文献
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ZHENG Wen-Chen WU Shao-Yi 《理论物理通讯》2001,(10)
According to a uniform and simple method of calculating spin-lattice coupling coefficients and the pert1rbation formulas of gi factors and hyperfine structure constants Ai based on the cluster approach for 3d7 ions in cubic,tetragonal and trigonal octahedral crystal fields, the spin-lattice coupling coefficients Fij (F11, Fl2, F44), Zij (Z11, Z12,Z44) and also g factor and hyperfine constant A for MgO:Co2 are calculated by using the parameters obtained from the optical spectra without adjustable parameters. The calculated results show good agreement with the observed values.The difiiculty in explaining the coeficients Fij and Zij is therefore removed.`` 相似文献
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Nezlin MV 《Chaos (Woodbury, N.Y.)》1994,4(2):109-111
In the context of planetary atmospheres and oceans, it is natural to define "coherent structures" as "long-lived," or "solitary," Rossby vortices. These can be described by the generalized Charney-Obukhov equation (in fluid dynamics) or the analogous generalized Hasegawa-Mima equation (in plasma physics). These two equations contain KdV-type nonlinearities which (together with the compensating dispersive spreading) determine the formation of the coherent structures and explain the clear-cut cyclonic/anticyclonic asymmetry observed experimentally in long-lived planetary Rossby vortices. Examples are given of natural vortices which are (and which are not) coherent structures. 相似文献
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Hadi Rezazadeh Hira Tariq Mostafa Eslami Mohammad Mirzazadeh Qin Zhou 《Chinese Journal of Physics (Taipei)》2018,56(6):2805-2816
In this paper, new exact analytical solutions of time-fractional Phi-4 equation are developed using extended direct algebraic method by means of conformable fractional derivative. The obtained new results reveal that the proposed method is effective to studythe nonlinear dispersive equations in mathematical physics. 相似文献
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E. Tobisch 《Journal of Experimental and Theoretical Physics》2014,119(2):359-365
We consider nonlinear gravity-capillary waves with the nonlinearity parameter ? ~ 0.1–0.25. For this nonlinearity, time scale separation does not occur and the kinetic wave equation does not hold. An energy cascade in this case is built at the dynamic time scale (D-cascade) and is computed by the increment chain equation method first introduced in [15]. We for the first time compute an analytic expression for the energy spectrum of nonlinear gravity-capillary waves as an explicit function of the ratio of surface tension to the gravity acceleration. We show that its two limits—pure capillary and pure gravity waves on a fluid surface—coincide with the previously obtained results. We also discuss relations of the D-cascade model with a few known models used in the theory of nonlinear waves such as Zakharov’s equation, resonance of modes with nonlinear Stokes-corrected frequencies, and the Benjamin-Feir index. These connections are crucial in understanding and forecasting specifics of the energy transport in a variety of multicomponent wave dynamics, from oceanography to optics, from plasma physics to acoustics. 相似文献
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New explicit exact solutions to a nonlinear dispersive-dissipative equation 总被引:1,自引:0,他引:1 下载免费PDF全文
Using the first-integral method, we obtain a series of new explicit exact solutions such as exponential function solutions, triangular function solutions, singular solitary wave solution and kink solitary wave solution of a nonlinear dispersive-dissipative equation, which describes weak nonlinear ion-acoustic waves in plasma consisting of cold ions and warm electrons. 相似文献
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General Jacobian elliptic function expansion method and its applications 总被引:11,自引:0,他引:11 下载免费PDF全文
An extended Jacobian elliptic function expansion method is presented and successfully applied to the nonlinear Schr?dinger (NLS) equation and Zakharov equation. We obtain some new solutions besides Fu et al's results. The results show that our method is more powerful to construct Jacobian elliptic function and can be applied to other nonlinear physics systems. 相似文献
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The equivalence between the propagation of dispersive modal fields in two-dimensional waveguides, and plane waves in a one-dimensional plasma is presented. Exploitation of this equivalence allows a time domain variant of the effective index approach to be used to model dispersive waveguides problems very efficiently. A time domain integral equation is developed for this important practical case and the stability of a computer algorithm based upon it is improved by means of both a semi-implicit formulation and the use of a modified space–time mesh. 相似文献