KT—5C托卡马克离子温度及其涨落的实验研究

在ＫＴ－５Ｃ托卡马克上成功建立了一套静电离子探针诊断系统，测量了ＫＴ－５Ｃ托卡马克从芯部到边缘的离了温度及其涨落，实验结果表明，在边缘等离子体离子温度高于电子温度，在芯部二者趋于一致。在我们的实验条件下，离子温度和电子温度的相对涨落量基本一致，而且都是电子密度相对涨落量大小的５０％。     

EAST等离子体电子温度涨落特征的初步实验研究

在EAST上使用相关电子回旋辐射(CECE)诊断系统观测到不同等离子体参数下的电子温度涨落特征,介绍了欧姆放电、L模放电及无ELM的H模放电的三种现象。在欧姆密度爬升等离子体中,电子温度涨落与电子密度之间表现出很强的相关性,即存在电子温度涨落处于较高水平的电子密度的窗口。初步分析表明,电子温度涨落变化是电子密度梯度和电子温度梯度共同影响的结果。不同辅助加热下的L模等离子体中,电子温度涨落的频谱表现出不同的行为。由于电子回旋共振加热(ECRH)的功率有限,其对电子温度的改变很小,而中性束注入(NBI)有较高的注入功率,能够明显提升电子温度,加热方式及加热功率大小引起的电子温度变化与电子温度涨落变化相关。在没有边缘局域模(ELM)的H模期间,可以观测到频率为18kHz的准相干模,其存在于归一化半径ρ=0.71～0.87较宽的径向范围内。     

有源介观LC电路中电源对量子涨落的影响

从有源ＬＣ电路运动方程出发，通过量子化有源ＬＣ电路和计算电压、电流的量子涨落，研究了电源对量子涨落的影响。     

激光在相对论磁化等离子体中的集体散射

激光在完全电解等离子体中集体散射截面等于单个电子的汤姆逊散射截面乘以结构因子，结构因子由电子密度涨落确定。在考虑电粒子间电磁相同作用基础上，给出激光在相对论磁化等离子体中散射的结构因子谱的解析表示式。     

磁场下MgB2的电导涨落效应

测量了磁场下MgB2的电阻与温度的依赖关系,测量结果表明,磁场下MgB2的临界涨落电导Δσ（H）符合由Ullah和Dorsey提出的关于临界涨落的三维标度方程,MgB2中较显著的临界涨落效应起源于其较高的超导转变温度和层状结构,由临界涨落电导符合三维的标度方程而不是二维,可推知MgB2中存在较强的层间耦合。     

激光输出不稳定性对激光与物质热作用的影响

研究了激光与物质相互作用中激光输出不稳定性对材料中温度场颁的影响以及减少这种影响的途径。首次在激光热传导方程中引入噪声项,推导了噪声影响下该激光热传导方程的解。研究发现,温度场的分布受噪声的影响,材料表面温度的涨落较大,而材料的深处涨落较小;温度场的涨落还和激光加热的过程有关,随激光加热时间的增长,温度场的涨落增大。此外,材料的热传导系数、热扩散率和发射率均对温度场的涨落有影响。文中还提出了减小激     

HT-7超导托卡马克边缘涨落谱特征及湍流输运研究

用郎缪尔三探针对HT-7超导托卡马克边缘等离子体涨落进行了高时空分辩测量.给出了欧姆放电下涨落幅度的径向分布、谱特征及传播特性.实验观察表明,在由E_r×B确定的极向旋转速度剪切层附近,等离子体电位、电子温度和电子密度的相对涨落水平和两两间的相干系数均有明显下降,其极向互相关函数亦减小,这说明剪切层对涨落具有去相关作用.由涨落驱动的径向局域粒子输运通量Γ_tur测量显示出湍动输运具有时间上的阵发特性。将悬浮电位涨落φ_f2的自动率谱P_{( 关键词： 托卡马克 边界涨落 湍流输运}     

染料激光色立方模型定态性质的描述

应用一般形式的统一色噪声近似得到了洒料激光色立方模型光强分布的福克－普朗克方程。导出了光强分布函数，描述了光强涨落的实验和数值模拟结果以及色噪声对光强涨落的影响。     

一种推导二能级原子自发辐射方法

考虑真空涨落能量为负的特点,提出一个能够简洁描述原子与真空涨落相互作用的方程,得到原子处于激发态的概率随时间变化的关系,讨论了原子自发辐射的速率与真空涨落的强度的关系.     

x射线激光在激光等离子体中传输变化及其对诊断的影响

通过引进误差判断参数η并进行数量级分析，得到了x射线激光在等离子体中传输时的 相位和幅度满足的演化方程. 结果表明，相位的演化与电子密度直接有关，幅度变化的影响 可以忽略不计；而幅度的演化却与相位直接相关，与电子密度没有直接联系. 进一步分析表 明，只需满足η<1即可利用逐级迭代近似分析方法得到x射线在激光等离子体中传输时 的相位与幅度的演化近似解，并用数值模拟证实了这些迭代近似解的可靠性和准确程度. 关键词： 激光等离子体 电子密度 逐级迭代近似 误差判断参数     

On the slow dynamics of density fluctuations near the colloidal glass transition

Slow dynamics of density fluctuations near the colloidal glass transition is discussed from a new viewpoint by numerically solving a nonlinear stochastic diffusion equation for the density fluctuations recently proposed by one of the present authors (MT). The effects of spatial heterogeneities on the dynamics of density fluctuations are then investigated in an equilibrium system. The spatial heterogeneities are generated by the nonlinear density fluctuations, while in a nonequilibrium system they are described by a nonlinear deterministic equation for the average number density. The dynamics of equilibrium density fluctuations is thus shown to be quite different from that of nonequilibrium ones, leading to a logarithmic decay followed by less distinct α- and β-relaxation processes. Received 9 March 2002 and Received in final form 19 September 2002     

跨声速流函数方程强隐式解及确定密度场的新方案

基于人工可压缩性对密度的修正,本文用强隐式格式快速求解了非正交曲线坐标系下跨声速流函数方程;在流函数场解出后,通过求解一个由动量方程、能量方程和连续方程组合而成的关于密度的一阶偏微分方程来获得密度场,因此流函数解法中常遇到的密度双值问题在这里已不存在;通常所讲的完成流函数场{Ψ}与密度场{ρ}间的迭代在本文便体现在流函数主方程与这个新推出的一阶微分方程间的迭代计算上;几个典型算例表明了本方法的有效性。     

New results on gas density, velocity field, and force field of a gasdynamic laser within a supersonic nozzle

Several new results are derived upon gas density as well as upon velocity and force fields relative to a gasdynamic laser within a supersonic nozzle. Evolution equations, including the continuity equation, are employed to obtain the above results. In particular, the continuity equation is used to determine the shape of the nozzle so that its cross-sectional area is calculated as a function of distance. This function is one of the ingredients to get our results relative to gas density, velocity, and force. In addition, the time-dependent power associated with the vibrational non-equilibrium expansion in the nozzle of hot gas at high pressure is evaluated.     

Density viscous continuum traffic flow model

A new traffic flow model called density viscous continuum model is developed to describe traffic more reasonably. The two delay time scales are taken into consideration, differing from the model proposed by Xue and Dai [Phys. Rev. E 68 (2003) 066123]. Moreover the relative density is added to the motion equation from which the viscous term can be derived, so we obtain the macroscopic continuum model from microscopic car following model successfully. The condition for stable traffic flow is derived. Nonlinear analysis shows that the density fluctuation in traffic flow induces density waves. Near the onset of instability, a small disturbance could lead to solitons determined by the Korteweg-de-Vries (KdV) equation, and the soliton solution is derived. The results show that local cluster effects can be obtained from the new model and are consistent with the diverse nonlinear dynamical phenomena observed in the freeway traffic.     

Gravitational Gauge Theory Developed Based on the Stephenson-Kilmister-Yang Equation

A Yang-Mills formulation of Einstein gravity with spin-affine connection as the dynamical variable of gravitational field is suggested based on the Stephenson-Kilmister-Yang (SKY) equation. A physically interesting property of the present formalism is that the Einstein field equation appears as a first-integral solution to the Yang-Mills type gravitational gauge field equation. The gravitational current density, the law of conservation and the gravitational gauge field strength in vierbein formulation are discussed. The present scheme could provide us with new insight into a possible way to include both Yang-Mills field and gravitational gauge field into one framework of generalized vierbein fields.     

A comment on the paper “Stochastic feedback, nonlinear families of Markov processes, and nonlinear Fokker-Planck equations” by T.D. Frank

The purpose of this comment is to correct mistaken assumptions and claims made in the paper “Stochastic feedback, nonlinear families of Markov processes, and nonlinear Fokker-Planck equations” by T. D. Frank [T.D. Frank, Stochastic feedback, non-linear families of Markov processes, and nonlinear Fokker-Planck equations, Physica A 331 (2004) 391]. Our comment centers on the claims of a “non-linear Markov process” and a “non-linear Fokker-Planck equation.” First, memory in transition densities is misidentified as a Markov process. Second, the paper assumes that one can derive a Fokker-Planck equation from a Chapman-Kolmogorov equation, but no proof was offered that a Chapman-Kolmogorov equation exists for the memory-dependent processes considered. A “non-linear Markov process” is claimed on the basis of a non-linear diffusion pde for a 1-point probability density. We show that, regardless of which initial value problem one may solve for the 1-point density, the resulting stochastic process, defined necessarily by the conditional probabilities (the transition probabilities), is either an ordinary linearly generated Markovian one, or else is a linearly generated non-Markovian process with memory. We provide explicit examples of diffusion coefficients that reflect both the Markovian and the memory-dependent cases. So there is neither a “non-linear Markov process”, nor a “non-linear Fokker-Planck equation” for a conditional probability density. The confusion rampant in the literature arises in part from labeling a non-linear diffusion equation for a 1-point probability density as “non-linear Fokker-Planck,” whereas neither a 1-point density nor an equation of motion for a 1-point density can define a stochastic process. In a closely related context, we point out that Borland misidentified a translation invariant 1-point probability density derived from a non-linear diffusion equation as a conditional probability density. Finally, in the Appendix A we present the theory of Fokker-Planck pdes and Chapman-Kolmogorov equations for stochastic processes with finite memory.     

爆炸电子发射边界的粒子模拟实现

 介绍了自行研制的全电磁柱坐标粒子模拟程序的电流分配方法和金属爆炸电子发射边界的模拟实现，该电流分配方法满足电荷电流连续性方程，避免了繁琐的泊松修正，适用于复杂边界物理问题的模拟研究。基于此电流分配方法的基础上，给出了建立在高斯定理基础上的简单且易于程序实现的阴极发射边界算法。利用该程序对平面二极管电子发射现象的模拟结果证明了算法的正确性。     

Probability and complex quantum trajectories

It is shown that in the complex trajectory representation of quantum mechanics, the Born’s ΨΨ probability density can be obtained from the imaginary part of the velocity field of particles on the real axis. Extending this probability axiom to the complex plane, we first attempt to find a probability density by solving an appropriate conservation equation. The characteristic curves of this conservation equation are found to be the same as the complex paths of particles in the new representation. The boundary condition in this case is that the extended probability density should agree with the quantum probability rule along the real line. For the simple, time-independent, one-dimensional problems worked out here, we find that a conserved probability density can be derived from the velocity field of particles, except in regions where the trajectories were previously suspected to be nonviable. An alternative method to find this probability density in terms of a trajectory integral, which is easier to implement on a computer and useful for single particle solutions, is also presented. Most importantly, we show, by using the complex extension of Schrodinger equation, that the desired conservation equation can be derived from this definition of probability density.     

Master Equation in Phase Space for a Spin in an Arbitrarily Directed Uniform External Field

The time evolution equation for the probability density function of spin orientations in the phase space representation of the polar and azimuthal angles is derived for the nonaxially symmetric problem of a quantum paramagnet subjected to a uniform magnetic field of arbitrary direction. This is accomplished by first rotating the coordinate system into one in which the polar axis is collinear with the field vector, then writing the reduced density matrix equation in the new coordinate system as an explicit inverse Wigner-Stratonovich transformation so that the phase space master equation may be derived just as in the axially symmetric case [Yu.P. Kalmykov et al., J. Stat. Phys. 131:969, 2008]. The properties of this equation, resembling the corresponding Fokker-Planck equation, are investigated. In particular, in the large spin limit, S→∞, the master equation becomes the classical Fokker-Planck equation describing the magnetization dynamics of a classical paramagnet in an arbitrarily directed uniform external field.