等离子体湍流理论研究的最新进展

评述和分析了磁约束核聚变理论研究、数值模拟和实验研究等方面最近几年共同关心的一个重要问题——寻找托卡马克等离子体湍流中的带状剪切流（zonal flows）。简要介绍了作者最近对电阻性-重力模湍流中的带状剪切流的研究结果。 Progress of the research on the zonal flows in tokamak plasma turbulence is surveyed, especially it is reviewed that the zonal flows observed in the experiments and numerical simulations on atmosphere turbulence and ocean turbulence and the discovery of H-mode in tokamak experiments how lead the researchers in magnetic confinement fusion community to find out the existence of the zonal flow in tokamak plasma turbulence and subsequently give the experimental verification of its existence. Finally, the results of our research on zonal flow generation and evolution in resistive-g mode turbulence are presented in brief.     

湍流喷注噪声定律的发展

本文对流体动力噪声的Lighthill理论进行了讨论,并导出与其U⁸定律等值的压力定律,即噪声总功率为
$W = 8KD^2 \\frac{{(P _1 - P_0)^4}}{{\\rho 0c0P_1^2}}$
K即Lighthill常数,D喷口直径,P₁和P₀分别为气室和大气压力。这个式子适用于低压冷空气喷注。进一步推广,求得高压阻塞喷注的湍流噪声、温度不同、喷注媒质不同也都适用的定律,以90°方向、距离1米处的声压级表示（dB,0dB=20μPa）,得
$L = 80 + 10\\log $ \\frac{{(R - 1)^4}}{{R^2 - R + 0.5}}$+ 20\\log $\\frac{{TM_0}}{{T_0M}} + 20\\log d$
其中,R=P/P₀,d=直径（mm）,T,M为工作媒质的温度和分子量而T₀,M₀为室温及空气分子量。压力定律完全符合实验结果,它更便于在实际中应用。过去作者等提出的经验公式非常接近理论公式。     

Onsager，林家翘与水动力湍流理论

提出量子涡旋（环流量）表象理论并率先得二维Ising模型严格解的诺贝尔奖得主Onsager也曾在水动力湍流理论上有重要贡献．最近美国的两位科学家Eyink及Sreenivasan在颇具影响力的期刊Rev．Mod．Phys．（2006．78（1）：87）上描述了Onsager与流体物理学者间的交流（有一些书信与手稿），其中一位是现在北京清华大学的林家翘教授（Lin C—C；同时为美国MIT教授）．     

漂移波湍流中“clumps”理论

本文基于Misguich和Balescu提出的轨道的随机处理发展了漂移波湍流中“clumps”的一种理论。指出clump效应不仅存在于非磁化湍性等离子体中也存在于磁化湍性等离子体中。它的存在使得实际横越磁场的扩散比Dupree理论预言的要小得多。导出了clumps寿命的一个明晰的表达式,它正比于横越磁场扩散的特征时间并对数地依赖于粒子的初始相对位置。 关键词：     

近代红外探测器的发展

一.引言自从1800年英国物理学家Herschel利用温度计在太阳光谱中发现了红外线之后,对红外辐射的研究和应用一直是处在发展缓慢的阶段中.其主要原因是当时的科学家们没有找到足够灵敏的红外接收器.直到最近数十年,各种性能、高灵敏度的红外接收器出现之后,红外     

近代高速示波管的发展

近代物理学和微波技术的发展,要求观测频带高于10,000兆赫的信号和10~(-9)—5××10~(-11)秒的瞬态过程。用一般示波器显示这类信号会遇到一系列的困难。主要的原因是一般示波管的极限频率约为几十兆赫,它不能正确显示小于几十分之一微秒的瞬态。为了克服     

近代电子光源的发展

一、前言火是第一个人造光源,直到十九世紀六十年代俄国軍事电气技师謝尔盖耶夫发明电灯以后,人造光源才进入一个嶄新的发展阶段。1903年钨絲真空白熾灯出現;1912—1913年充气白熾灯,单螺旋、双螺旋鎢絲灯相继問世,直到今天,这些电气光源还被广泛地应用着。本文不打算談論这些光源,而是把十九世紀末、廿     

超声速湍流边界层湍流统计与湍流结构分析

可压缩边界层转捩问题与湍流问题一直是制约高超声速飞行器发展的关键基础问题,也是近年来流体力学领域研究的热点问题.采用直接数值模拟方法,获得了空间发展的Ma=2.25超声速湍流边界层流场,通过对湍流边界层的发展状态进行评估,得出有效的Reynolds数Reθ 范围约为2600～4600.对壁面摩阻系数开展了分解,获得了各...     

用小波理论研究湍流边界层湍动能的特征

在三个雷诺数下,用热线风速仪测量了光滑壁面湍流边界层的脉动速度信号,利用离散正交小波理论分解该测试信号,得到具有最大湍动能的分量及其发生频率,并得到了这两个参数沿ｙ＋的分布曲线．分析表明,在试验雷诺数下,最大湍动能的无量纲尺度沿ｙ＋分布雷诺相似,其发生频率沿ｙ＋基本是一常数,且湍动能主要集中在几个有限的尺度分量上．     

非柯尔莫哥洛夫湍流光束漂移的理论研究

一直以来, 大气湍流对空间光通信影响的研究都是在柯尔莫哥洛夫(Kolmogolov)湍流理论的框架内进行, 该模型已经被人们广泛接受和使用。然而, 近年来国内外众多非柯尔莫哥洛夫(Non-Kolmogolov)湍流的实验报道则表明Kolmogolov湍流理论有时不能完全正确地描述大气湍流的统计规律, 尤其在对流顶层和平流层。为了全面了解大气湍流对空间光通信的影响, 研究Non-Kolmogolov湍流对光波传输的影响成为了首先要面对的问题。基于Non-Kolmogolov湍流功率谱密度, 运用几何光学近似方法推导了弱起伏条件下准直光束和聚焦光束的光束漂移方差, 并给出了简洁的解析表达式; 然后, 利用这一表达式进行了仿真分析。     

等离子体强湍流在Gauss随机过程中的平均传播量理论

本文在Gauss随机过程的基础上建立了描写等离子体强湍流的平均传播量的理论,证明了群的性质,分析了它的物理意义及基本应用,指出这一理论和Misguich-Balescu所提出的RQL弱耦合理论相比是对等离子体强湍流更好的描述。     

非均匀等离子体湍流的重正化准线性理论——Misguich-Balescu理论的推广

本文把Misguich和Balescu建立的均匀等离子体湍流的重正化准线性理论推广到非均匀等离子体湍流。在弱耦合和弱非均匀性近似下,得到传播算符和平均湍性碰撞算符的明晰表达式。非均匀性除对算符中的扩散贡献、共振加宽或频移、Dupree衰减和平均分布函数在速度空间的陡度效应等作出一定的修正之外,还引出新的指数微分算符:在传播算符中是涨落电场关联函数非均匀性导致的新的速度微分算符,在平均湍性碰撞算符中是平均分布函数非均匀性导致的新的空间微分算符。平均分布函数非均匀性还使得在平均湍性碰撞算符中出现的两个互为逆运算的自由流传播算符不能抵消,从而使包含在(直接作用于平均分布函数的)传播算符中的非马尔可夫效应显露出来。 关键词：     

A KINETIC THEORY OF TURBULENCE

This paper deals with a method of treating problems of Turbulence from a kinetic point of view. Turbulence "temperature", "pressure", and "entropy" are first defined as state functions, and then the pressure and temperature are incorporated into the equations of motion. Turbulent flows through a circular pipe and between parallel planes are considered in some detail, while the problems of turbulence decay, turbulence structure, and correlation characteristics are briefly discussed. Practically in all cases, the constancy of the turbulence temperature is found to play an important role.     

非均匀等离子体湍流的重正化准线性理论(Ⅰ)——Misguich-Balescu理论的推广

本文将Misguich和Balescu的理论推广到非均匀等离子体的情形,导出了包括非均匀性效应的扩散方程与扩散张量的表式以及色散关系。指出Pelletier等人对等离子体湍流可作马尔科夫近似处理的论证完全不适用于非均匀等离子体湍流的问题。 关键词：     

托卡马克等离子体边缘梯度和杂质辐射驱动的湍流理论

本文考虑了托卡马克等离子体边缘的物理性质，由电子连续性方程和离子动量平衡方程导出了电子密度演变方程。分析了各种驱动源在线性和非线性发展过程中的作用。电子密度梯度直接影响密度涨落，并通过杂质辐射与温度涨落相互耦合，进而影响静电势涨落。理论结果能够分别与高、低密度装置上的实验较好地相符合。     

二元合金超格学说中准化学方法之推广

本文推广准化学方法二元合金超格学说中之应用於合金之任何组成成分,所得式与组成在一比一时者极相似。最後对於AuCu₃之合金有较详之讨论。     

Kaluza理论的运动定律

本文指出,如同在广义相对论中粒子运动方程是场方程的推论一样,在引力场与电磁场的Kaluza统一理论中,粒子的运动方程也是场方程的一个推论,即带电粒子在引力场和电磁场中的运动方程可以从Kaluza统一理论中的场方程推导出来。本文进而在Minkowski时空的条件下,借助Maxwell理论的Kaluza形式,得到Maxwell方程也包含了带电粒子运动方程的结论。 关键词：     

论弹性体力学与受范性体力学中的一般变分原理

In this paper, some general variational principles in the theory of elasticity and the theory of plasticity are established. Consider an elastic body in equilibrium with small displacement. By regarding u, v, w, e_x, e_y, e_z, y_yz, y_xz, y_xy, σ_{x,σy, σz,τyz,τxz,τxy as fifteen independent functions, and letting their variations be free from any restriction, we establish two variational principles, called the principle of generalized complementary energy and the principle of generalized potential energy. Each principle is equivalent to the four sets o?fundamental equations of the theory of elasticity, namely, the equations of equilibrium, the stress strain relations, the strain displacement relations and the appropriate boundary conditions. Special cases of these principles are examined. These principles are next expressed in other forms, where u, v, w, σx,σy, σz,τyz,τxz,τxy are regarded as nine independent functions with their variations free from any restrictions. Next we consider the bending of a thin elastic plate with supported edges under large deflection. By regarding Mx, My, Mxy, Nx, Ny, Nxy, u, v, w as nine independent functions with the restriction that w should vanish along the contour of the plate, we establish a variational principle, called the principle of generalized potential energy, which is equivalent to the three sets of fundamental equations in the theory of bending of thin plate, namely, the equations of equilibrium, the displacement stress relations (strain stress relations) and the appropriate boundary conditions. This principle is next expressed in another form which is more convenient for application. As an illustration, von Kármán's equations for the large deflection of thin plate are derived from this principle. In von Kármán's equations, one unknown is the deflection and the other unknown is the membrane stress function. Therefore it is impossible to derive von Karman's equations either from the principle of minimum potential energy or from the principle of complementary energy. Finally we consider the equilibrium of a plastic body with small displacement. In the case of the deformation type of stress strain relations, we establish two variational principles, each of which is equivalent to the equations of equilibrium, a certain type of stress strain relations and the appropriate boundary conditions. In these variational principles, u, v, w and their variations are free from any restriction, and σx,σy, σz,τyz,τxz,τxy and their variations satisfy a certain yield condition. In the case of the flow type of stress strain relations, we get two similar variational principles, in which u, v, w and their variations are free from any restriction, σx,σy, σz, τyz,τxz,τxy and their variations satisfy a certain yield condition and σx,σy, σz, τyz,τxz,τxy have no variations.}     

THE BEHAVIOR OF THE PHASE-SHIFT IN THE BAKAMJIAN-THOMAS THEORY

The behavior of the phase-shift of the Bakamjian-Thomas theory and its relationwith the phenomenological nuclear force V=V_RiV_I at high energy are explored.Two limits are obtained:It is found that the repulsive core with a sharp outer edge may induce a characteris-tic oscillation of Re δ₁,and Im δ₁ is sensitive to V₁.The conclusion is that the analy-sis of the phase-shift extending to higher energy is relevant in determining therepulsive core and the imaginary part of the nuclear force.     

THE PROBLEM OF MOTION IN THE KALUZA THEORY

It is shown that the equations of motion for a charged massive particle are consequences of the field equations in Kaluza unification theory of gravitation and electromagnetism, i.e., the equations of motion for the particle can be deduced from Kaluza field equations, just as that in Einstein's theory of motion of general relativity the equations of motion for a massive particle are consequences of the Einstein equations. Furthermore, the Lorentz equations for a particle maving in the Maxwell electromagnetic field on the Minkowskian space-time can also be obtained from the Maxwell equations by means of the Kaluze mechanism of the Maxwell theory.