温度梯度驱动托卡马克边缘湍流中的密度梯度效应

把密度梯度驱动效应引入到温度梯度驱动的托卡马克边缘湍流模型当中来,在磁流体力学基础上建立了新的湍流理论,研究了这种湍流过程的物理机制,阐明了密度梯度在线性和非线性发展阶段所起的作用,并指出了它对湍流饱和的贡献,导出了静电势和密度涨落的饱和水平以及相应的粒子扩散系数。这些理论结果都与TEXT装置上的实验相符合。     

γ射线在水中绕圆柱形屏蔽体的散射

用外包“过滤片”的CTC-6型薄壁β计数管,测量了各向同性Co~(6O)点源的γ射线在水中绕圆柱形屏蔽体散射到屏蔽体后的轴向剂量分布.结果表明:分布有峯值存在,当源的位置改变时,峯的位置也有小的移动.实验结果与两种理论计算进行了比较:(1)二次散射近似法的计算值与实验值的总趋势是一致的,但普遍低于实验值;(2)蒙特-卡罗-统计估计法的计算值与实验值基本上是符合的.实验与两种理论计算比较的结果都表明了,对探测点的剂量页献最大的是沿屏蔽体边缘、路径同圆柱形屏蔽体轴心线在同一平面上且与轴心线平行散射的光子.     

托卡马克旋转等离子体中阿尔芬波电流驱动

随着托卡马克实验的发展,人们正在寻求和研究多种更适合先进托卡马克高约束性能等离子体的电流驱动方法,然后加以比较和选择。尽管达到兆安量级的低杂波电流驱动已经在许多托卡马克上取得成功,但低杂波不能渗透到反应堆尺寸的托卡马克等离子体芯部和低杂波电流驱动效率会随着等离子体密度增加而     

Low-Frequency Waves in a Magnetized Collisional Dusty Plasma

1.IntroductionAdustyplasmaisathree-componentplasmacon-sistingofelectrons,ionsandmassivesoliddustgrainsheldinsuspension.Thegrainsusua1lychargeneg-ativelytoalargevaIue[l].TheycommonlyoccurinspaceaJswellaslaboratory.Intypicallaboratoryplasmasthedustgralnsacquireanegativechargeduetoadominantcollectionofthemoremobileelec-trons.Atypicalisolated1pm-sizedustgraininaplasmawi1lhaveamasscorrespondingto1O12protonmass(m.)andachargeofafewthousandelectrons[2].lntroducingofathirdcomponentwlthh1ghlychargedan…     

Tunability of One-Dimensional Plasma Photonic Crystals with an External Magnetic Field

We investigated in detail how photonic band structures (PBSs) of one dimensional plasma photonic crystals (PPCs) are tuned after being exposed to an external magnetic field. We showed that the properties of PBSs of PPCs are tuned correspondingly because the dielectric constant of the micro plasma layer is modified differently in different frequency ranges due to magneto-optical effects. Two numerical cases are calculated and discussed to study the magnetooptical effects on the properties of PBSs, including the Faraday and Voigt effects.     

Basic Features of E×B Convection Nonlinearity in Tokamak Plasmas

Basic features of E×B convection nonlinearity in tokamak plasmas, especially, large-scale coherent structures, are studied on the basis of both the model of three coupled modes and the model of four coupled modes. The difference of our models with the most existing models is that we deal with a linearly unstable system such as the ion-temperate-gradient (ITG) driven turbulence in tokamaks. Two types of coherent structure are identified with spatio-temporal characteristics called a zonal flow (ZF), and an oscillating shearing flow (OSF), respectively. At the same time, the anomalous heat fluxes in the system are analyzed in some details. Results show that the two types of coherent structure play different roles in both the plasma turbulent fluctuations and the related anomalous transports. Moreover, only the large-scale coherent structure with zero frequency, namely, the zonal flow, can suppress the turbulent fluctuations effectively and hence benefits tokamak plasma confinements.     

阿尔芬波加热托卡马克等离子体的能量平衡计算

介绍了求解阿尔芬波加热托卡马克等离子体的能量平衡问题的一种数值计算方法。文中给出了部分计算结果,它与实验结果符合很好。该方法不仅简便、直观、节省计算时间,并对其它波加热动力学问题也适用。     

Comparison Between Mitigation Effects of the Finite Larmor Radius and Sheared Axial Flow on Rayleigh—Taylor Instability in Z—Pinch Implosions

A magnetohydrodynamic (MHD) formulation is derived to investigate and compare the mitigation effects of both the sheared axial flow and finite Larmor radius (FLR) on the Rayleigh-Taylor (RT) instability in Z-pinch implosions. The sheared axial flow is introduced into MHD equations in a conventional way and the FLR effect into the equations via ?/?t → -i(w+ik⊥2pi2Ωi), as proposed in our previous paper [Chin. Phys. Lett. 2002, 19:217] , where k⊥2 pi2 is referred to FLR effect from the general kinetic theory of magnetized plasma. Therefore the linearized continuity and momentum equations for the perturbed mass-density and velocity include both the sheared axial flow and the FLR effect. It is found that the effect of sheared axial flow with a lower peak velocity can mitigate RT instability in the whole wavenumber region and the effect of sheared axial flow with a higher one can mitigate RT instability only in the large wavenumber region (for normalized wavenumber k>2.4); The effect of FLR can mitigate RT     

Assembling Stabilization of the Rayleigh-Taylor Instability by the Effects of Finite Larmor Radius and Sheared Axial Flow

The assembling stabilizing effect of the finite Larmor radius (FLR) and the sheared axial flow (SAF) on the Rayleigh-Taylor instability in Z-pinch implosions is studied by means of the incompressible finite Larmor radius magnetohydrodynamic (MHD) equations. The finite Larmor radius effects are introduced in the momentum equation with the sheared axial flow through an anisotropic ion stress tensor. In this paper a linear mode equation is derived that is valid for arbitrary kL, where k is the wave number and L is the plasma shell thickness. Numerical solutions are presented. The results indicate that the short-wavelength modes of the RayleighTaylor instability are easily stabilized by the individual effect of the finite Larmor radius or the sheared axial flow. The assembling effects of the finite Larmor radius and sheared axial flow can heavily mitigate the Rayleigh-Taylor instability, and the unstable region can be compressed considerably.