环流器等离子体压强分布关于理想磁流体气球模的最佳化

大家知道,环流器等离子体关于气球模的稳定性条件对等离子体比压值给出了最严厉的限制,对圆戳面环流器,典型的按体积平均比压值仅为(1—2)％,远低于反应堆的设计要求。许多人已对提高这一临界比压值的各种可能性进行过讨论,最近的研究指出,动力效应对于气球模不稳定性的阈值影响甚微,不过可使不稳定性的增长率降低很多。可是,我们曾发现,可以存在比压值很高的平衡位形,它们对于局部Mercier模是稳定的。这类平衡位形的特点是其q-剖面由等离子体中心向边缘下降。本文目的为验证这类位形相对于最危险的磁流体模式,即气球模的稳定性。     

含第二稳定区的环流器微观气球模分析

本文导出了可用于研究含第二稳定区的环流器微观气球模的本征方程,其中保留了各种最重要的动力效应。对圆截面环流器,相应的本征方程中保留了对第二稳定区中模的特性有重大影响的磁面位移效应及极向场曲率效应。采用数值打靶法求解本征方程,详细分析了各种位形参数对模的结构及稳定性的影响。与理想磁流体理论结果对比,发现在第二稳定区参数范围内,存在一类新的弱不稳定模式。此外,在各种参数范围内都存在临界稳定模式。详细考察了这些模式的存在形式及结构,以及剪切和极向场参数对它们的影响。 关键词：     

欧姆驱动托卡马克平衡位形的确定

托卡马克平衡位形的确定是磁约束聚变装置研究和实验与理论分析研究的最基本任务。通常采用的方法是假设等离子体压强p和极向电流通量函数F为极向磁通ψ的某种形式的函数（常常假定为ψ的多项式，一般为二次多项式），然后求解关于ψ的Grad—Shafranov方程。     

非圆截面环流器等离子体对于高n理想磁流体气球模的最佳压强分布

本文假定等离子体局部压强梯度由理想磁流体高n气球模所限定,讨论了非圆截面环流器的最佳压强剖面。分析了椭圆及三角变形的效应,发现三角变形对提高稳定性很有利;q剖面对平均比压值及中心比压值都有强烈影响,而沿半径下降的q剖面对提高比压值很有利。     

快加热环流器等离子体的位形演变

本文讨论了环流器等离子体在快加热过程中位形演变的近似描述问题。对两类重要的通量守恒演变系列,即绝热压缩和非压缩快加热,具体计算了平衡解。假定等离子体截面形状有任意的小变形,但初态位形只有一个椭圆磁轴,所用近似方法基于对反环径比展开。结果表明,这一方法可以成功地描述绝热压缩演变系列;对非压缩快加热,在磁轴位移不很大时,所得结果与严格的二维通量守恒解是相符的。 关键词：     

2-(2,5-二羟苯基)四苯基卟啉及其金属配合物的合成与表征

对苯二酚与 2 硝基 5 ,10 ,15 ,2 0 四苯基卟啉 1及其铜 (Ⅱ ) 2、镍 (Ⅱ ) 3、锌 (Ⅱ ) 4等金属配合物直接加热反应 ,分别制得 2 (2 ,5 二羟苯基 )四苯基卟啉 1′(81% )及相应金属配合物 2′(71% ) ,3′(6 1% ) ,4′(40 % )。它们的结构由IR ,MS ,UV及1 HNMR ,2D NMR等确定。发现对苯二酚通过碳 碳键与卟啉的吡咯环直接相连 ,氢醌与卟啉环趋于共平面 ,其中一个羟基位于卟啉环的去屏蔽区 ,H原子的核磁位移向低场移动 (δ =7 5 2 ) ,另一个则处于中位苯环的屏蔽区 ,H原子的核磁位移为δ =4 18;氢醌环上的质子也表现出不同的核磁位移 ,其中 6位上H的位移值为δ =4 93,明显向高场位移。     

中国环流器2号A托卡马克弹丸注入放电中空电流与反磁剪切位形

具备弱剪切或负磁剪切和内部输运势垒的托卡马克运行方式被认为是提高聚变性能的最有前途的方法.中空电流密度剖面与反磁剪切位形是改进堆芯约束和形成内部输运垒的关键条件之一.在中国环流器2号A(HL-2A)弹丸注入实验中,成功地实现了维持时间约为100 ms的中空电流放电.伴随着中空电流剖面的形成,同时形成了反磁剪切位形.由于欧姆加热功率不太高,且没有外部辅助加热,只能在稳定的中空电流放电阶段看到内部输运垒形成的趋势.在弹丸注入后,电子热扩散系数显著降低,说明弹丸深度注入改善了能量约束.等离子体性能的增强:一方面是由于弹丸注入造成中心高度峰化的电子密度剖面;另一方面是由于等离子体中心存在负磁剪切.同时,中空电流位形有利于改善高密度等离子体的稳定性.结果还表明,在中空电流放电中,等离子体比压值是低的.为了提高βN极限,可在等离子体边界附近放置导电壁.HL-2A弹丸注入实验的结果,为在限制器托卡马克上获得高参数放电提供了一种可能.     

剪切磁场位形下电阻壁模不稳定性的数值模拟

数值研究了平衡磁场位形对电阻壁模稳定性的影响。研究发现,磁场剪切对电阻壁模有解稳作用,对于不同的剪切磁场位形,最不稳定的电阻壁模的环向模数和极向模数不同。等离子流对电阻壁模的增长有抑制作用,稳定住电阻壁模的临界流速度随着磁场剪切率的增大而增大。电阻壁模经线性增长后,进入非线性演化阶段,最后达到饱和状态,剪切磁场位形下的扰动磁能比均匀磁场位形下的扰动磁能饱和度高。     

剪切磁场位形下电阻壁模不稳定性的数值模拟

数值研究了平衡磁场位形对电阻壁模稳定性的影响。研究发现,磁场剪切对电阻壁模有解稳作用,对于不同的剪切磁场位形,最不稳定的电阻壁模的环向模数和极向模数不同。等离子流对电阻壁模的增长有抑制作用,稳定住电阻壁模的临界流速度随着磁场剪切率的增大而增大。电阻壁模经线性增长后,进入非线性演化阶段,最后达到饱和状态,剪切磁场位形下的扰动磁能比均匀磁场位形下的扰动磁能饱和度高。     

由磁测量确定环流器等离子体截面形状的方法

一、引言在环流器实验中,等离子体柱截面形状和位置是位形基本参数。尤其对非圆截面和放电期间截面变化的装置,为调节、控制成形、分析等离子体内外电流分布变化引起的位形和稳定性改变,边界磁面形状位置是不可缺少的信息。本文用给定极向磁场,由拟合计算的方法来确定等离子体边界。     

The 1+− state and ψ spectroscopy

We suggest that ψ′ → ψ H^πO (where the ψH is the 1^+? state) may be an important decay mode of the ψ′(3685) and ψ″′ → ψ_H^η of the ψ″′ (4414). We also discuss ways to test the magnitude of the η?π^O transition in the ψ system.     

TOKAMAK BALLOONING MODE STUDIES-(I)

In this paper, the first part deals with the structure of the second stability regime of the ideal MHD ballooning modes in circular tokamaks. It is shown that in high-beta regime,the poloidal magnetic field destabilizes strongly the plasma and can eventually lead to the appearance of a new instability regime at modest beta-value for a flat q-profile. In the second part, th a various kinetic effects on ballooning modes or high-beta tokamaks are calculated. Results show that a new weak ballooning mode branch can exist in the second MHD stability regime in addition to the MHD-like strony ballooning mode branch in the first instability regime with its growth rate decreased by kinetic stabilizations.     

Are the ψ′→η c γ,ψ″→η c γ decays due to the gluon admixture?

We propose a new method for estimating the radiative transitions between the excited 1^? charmonium levels and η_c. The method is based on QCD (plus the hypothesis of local duality) and makes no reference to the standard potential picture. It is argued that the decay ψ′(3.698)→η _c γ is essentially due to the gluon admixture in the Ψ′ wave function. The most naive analysis yields approximately 0.15 keV for the ψ′→η _c γ decay width, five times smaller than preliminary data. The experimental number for Γ(ψ′→η _c γ)—0.7 keV—can be reproduced only at a price of introducing a rather large ψ″(3.772)→η _c γ amplitude, Γ(ψ″→η _c γ)～1 keV. As a byproduct, we get a reliable prediction for the ρ→πγ decay rate, Γ(ρ→πγ)≈70 keV, in good agreement with a recent measurement.     

On the dynamic mean field theory of spin glasses

We derive in detail Sompolinsky's mean field theory of spin glasses using a diagram expansion of the effective local Langevin equation of Sompolinsky and Zippelius. We use a simpler generating functional than in the literature, on which the quenched average is very easily done. We pay special attention to the existence of an external field. We show that there are two different types of singularities for ω=0 in the equations. The first type, which leads to Parisi'sq(0), is connected with the local magnetisation. The second type, which leads toq′(x), is connected with the nonergodic behaviour. We show that the continuous limit of discrete Sompolinsky solutions has to be taken in order to be in accordance with the fluctuation dissipation theorem on infinite time scales. We discuss carefully the question of dynamical stability. We show that Sommers' solution is unstable only on an infinite time scale and thus remains an acceptable equilibrium theory with a broken symmetry. We argue that for ω=0 a formal violation of the fluctuation dissipation theorem is physically expected if the relaxation times are of the order of the switching time of the external field. From this point of view the spin-glass state is a steady state but not a real equilibrium state.     

环流器等离子体高n气球模的第二稳定区

本文讨论了圆截面高比压等离子体关于高n气球模的稳定性,在高比压情况下,相应的极向磁场对气球模有相当强的驱动作用,从而严重影响了第二稳定区的结构,我们详细计算了不同剪切、不同压强梯度及不同极向场参数对气球模本征函数和本征频率的影响,这些结果比较完善地反映了圆截面环流器中理想磁流体气球模理论所预示的主要结论。 关键词：     

NONLINEAR STABILITY ANALYSIS OF THE EMDEN–FOWLER EQUATION

In this paper, we qualitatively study radial solutions of the semilinear elliptic equation Δu+uⁿ = 0 with u(0) = 1 and u′(0) = 0 on the positive real line, called the Emden–Fowler or Lane–Emden equation. This equation is of great importance in Newtonian astrophysics and the constant n is called the polytropic index.

By introducing a set of new variables, the Emden–Fowler equation can be written as an autonomous system of two ordinary differential equations which can be analyzed using linear and nonlinear stability analysis. We perform the study of stability by using linear stability analysis, the Jacobi stability analysis (Kosambi–Cartan–Chern-theory) and the Lyapunov function method. Depending on the values of n these different methods yield different results. We identify a parameter range for n where all three methods imply stability.     

Delta Excitation in Compressed Neutron Rich Double Magic Spherical Finite Nucleus 132Sn

The ground state properties of 132Sn at equilibrium and at large compression are investigated,within the framework of the radially constrained spherical Hartree-Fock(CSHF)approximation.The delta resonance effects on the properties of neutron-rich double magic spherical nucleus,132Sn,in its ground state and the state under static compression are studied.The sensitivity of the nucleon size and Δ model spaces is investigated.At equilibrium,mixing between nucleon and Δ's in the largest model space of nine major nucleon shells plus 10 Δ orbitals was found.Expanding the nucleon model space has a larger effect on reducing the static compression modulus and softe-ning the nuclear equation of state than increasing the number of Δ states.It was found that the most of the increase in the nuclear energy generated under compression is used to create the massive Δ particles.For 132Sn nucleus under compression at 12 times the normal nuclear density,the excited nucleons to Δ's increased sharply up to 13% of the total number of constituents.This result is consistent with the values extracted from relativistic heavy-ion collisions.The single particle energy levels calculated and their behaviors under compression are examined too.A good agreement between results with effective Hamiltonian and the phenomenological shell model for the low lying single-particle spectra is obtained.     

Study of (∧) decay parameter in J/ψ→∧(∧)decay

The helicity amplitudes fot J/ψ→∧(∧)and the relevant background decays are presented for measuring the A decay parameter α+((∧)→(p)π)in J/ψ→∧(∧).The Monte Carlo(MC)simulations based on the helicity amplitudes information are carried out.The likelihood fit method to determine the A decay parameter is presented.Based on the MC generated sample,the sensitivity of the measurement for α+has been estimated,which shows that the J/ψ→∧(∧) channel can be used to measure the A decay parameter α+((∧)→(p)π+)well.     

石墨表面吸附钾系统电子性质的理论研究

基于集团模型电荷自洽的EHT(Extended Hückel Tneory)方法对K在石墨(0001)表面吸附态进行了优化计算.在3种不同的覆盖度(Θ)下,对k-石墨系统的电荷转移量△Q、吸附能△E、态密度PDOS和TDOS、Mulliken集居数和成键性质进行了比较.认同K/石墨吸附系统是石墨插层化合物(GIC)的雏型.并用LMTO方法对KC₈完成电子结构的第一性原理研究,得到与EHT完全一致的结果:K4s-Ca杂化态主要位于低能区域远离费米能级,构成反键轨道其电子转移到费米能级附近K3d-Cπ成键的杂化轨道上.空的3d轨道在目前EHT方法和LMTO方法计算中扮演了关键角色.这与其他文献K-4s态处在EF能级的结果不同,但与早期Fischer(1984),Johnson(1986)XPS,ARUPS的实验结果吻合.     

环位形下鱼骨模驱动快离子输运的数值模拟研究

考虑包含动理学效应的鱼骨模结构,使用导心轨道程序 ORBIT,在磁面坐标下研究了不同的扰动模 幅度、频率对快离子再分布的影响,并分析了粒子与扰动发生共振的条件。模拟得出,鱼骨模扰动会使快离子在 实空间、相空间中发生再分布,芯部( ψ_p/ψ _w≤0.2 ,ψ_p 为极向磁通,ψ_w 为最后一个闭合磁面的磁通)快离子密 度下降约 20%,中间磁面位置上( ψ_p/ψ _w≥0.2,ψ_p/ψ _w≤ 0.6)的快离子密度增加约 7%;通过扫描频率发现,相空间中快 离子的再分布对模式频率敏感,并分析了快离子与鱼骨模扰动共振的条件。