托卡马克能量约束及自举电流效应的初步考虑

基于Lee等人的离子温度梯度模导致的反常热能输运系数,本文研究了辅助加热托卡马克等离子体的能量约束行为,并对自举电流的效应作了初步考虑。结果表明,计算得到的能量约束时间随等离子体电流I_p和托卡马克大半径R增大而增长,随注入功率P_t、环向场B_t以及等离子体小半径α的增大而缩短。这些结果与Kaye-Goldston的经验约束定标具有相同的趋势。自举电流的存在总是导致能量约束时间的增加,当自举电流与总电流的比值γ较小时,能量约束时间的增加率约为γ/2。此外,自举电流将造成锯齿反转半径的减小。     

Tokamak中自举电流的剖面准直性

利用Harris模型,通过求解等离子体平衡方程,计算俘获粒子份额,分别对常规剪切和中心负剪切下tokamak中的自举电流的大小和剖面准直性进行了计算和分析.自举电流分布与等离子体平衡电流分布之间的剖面准直性可以通过调整等离子体的密度、温度和电流分布参数,以及描述等离子体形状的拉长度k和三角变形因子d来获得.中心负剪切位形有利于自举电流产生,并有好的剖面准直性.通过计算比较,分别在常规剪切位形下和中心负剪切位形下获得了一组优化的等离子体参数,在这组参数下,自举电流有较大的份额和好的剖面准直性 关键词： tokamak 自举电流 剖面准直性     

稳态托卡马克堆中的自举电流

在稳态托卡马克堆的燃烧阶段,当感应电流下降后,新经典输运产生的自举电流便成为维持稳定电流的最好手段。本文根据α粒子新经典自举电流的最新结果,计算了感应电流消失阶段,稳态堆中α粒子、电子和离子的自举电流。     

稳态托卡马克堆中自举电流定标准和驱动电流的一些讨论

在设定自举电流为托卡马克堆中固有电流的基础上，根据是否存在ａ粒子和驱动电流的不同情况，本文讨论了自举电流的定标准和维持不变的总电流及其分布所需的驱动电流之大小及分布。     

稳态托卡马克堆中自举电流定标律和驱动电流的一些讨论

在设定自举电流为托卡马克堆中固有电流的基础上，根据是否存在α粒子和驱动电流的不同情况，本文讨论了自举电流的定标律和维持不变的总电流及其分布所需的驱动电流之大小及分布。     

非理想MHD效应与m=1内扭曲模本征方程

对非俘获粒子与俘获粒子分别采用流体和单粒子模型，推导了同时包含各种非理想ＭＨＤ效应的ｍ＝１内扭曲模本征方程，这些效应包括有限电阻，反磁漂移，俘获离子引起的增大的极化漂移与横向粘滞，沿力线电子热导，反常电子横和粘滞，俘获离子香蕉轨道宽度及自举电流等效应，所得到的ｍ＝１内扭曲模本征方程，为研究不同情况下各种非理想ＭＨＤ效应的相对重要性及可能以ｍ＝１内扭曲稳定性的影响，提供了一可靠的基础。     

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研究了在托卡马克装置中中性束注入时快离子自举电流的产生。利用快离子分布函数在两小增量δ=ρp/a (ρp是极向拉莫尔半径,a是小半径)和δ*=τB/τs(τB是俘获粒子反弹周期,τs是慢化时间)下进行展开的方法求解漂移动力学方程;给出了快离子自举电流的一般表达式。计算了圆截面大纵横比托卡马克中快离子自举电流密度分布和总的快离子自举电流的大小,研究表明：在中性束垂直注入时快离子自举电流约占总电流10%;自举电流的大小既敏感地依赖于中性束注入的角度——平行注入时较小、接近垂直时迅速增大,同时也较强的依赖于快离子的产生速度与临界速度的比值,即vb/vc,而vb2∝E(束能量);自举电流的大小随注入束能量的增加而迅速增大。     

小磁岛转动引起的沿磁力线电流对撕裂模的影响

利用离子香蕉轨道中心坐标和香蕉轨道平均算符,讨论了磁岛转动引起的沿磁力线电流分布及其对新经典撕裂模演进的影响。结果显示,考虑此电流的影响,当磁岛旋转频率ω=ω_*i 时,被离子香蕉轨道宽度效应削弱的自举电流驱动项基本恢复;当ω=ω_*e时,离子香蕉轨道宽度效应对自举电流驱动项的削弱则加剧。这意味着磁岛转动方向不同时,此沿力线电流能显著增大或减弱离子香蕉轨道宽度效应对自举电流驱动项的削弱作用。     

基于垂直磁场压缩的EAST等离子体初步研究

基于等离子体参数随大半径/小半径变化的规律,分析了电流平顶段垂直磁场与相关等离子体参数的关系。垂直磁场的非线性部分用于分析非感应电流驱动效应,包括自举电流效应。此外,对于给定的等离子体电流,推导了平顶段垂直磁场与线平均密度之间的关系,并进一步研究压缩后的等离子体。基于EAST第41195次放电的数据分析表明,垂直磁场强度的增大可以使得等离子体温度、密度、β_p和自举电流份额获得提升,为等离子体参数高参数,特别是β_p提供了一种可能性参考。     

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利用离子香蕉轨道中心坐标和香蕉轨道平均算符,讨论了磁岛转动引起的沿磁力线电流分布及其对新经典撕裂模演进的影响.结果显示,考虑此电流的影响,当磁岛旋转频率ω=ω*i时,被离子香蕉轨道宽度效应削弱的自举电流驱动项基本恢复;当ω=ω*e时,离子香蕉轨道宽度效应对自举电流驱动项的削弱则加剧.这意味着磁岛转动方向不同时,此沿力线电流能显著增大或减弱离子香蕉轨道宽度效应对自举电流驱动项的削弱作用.     

On the possible role of the bootstrap effect in the RF current drive experiments

Conditions of existence of the bootstrap effect at anomalous diffusion in tokamaks are discussed. Assuming that these conditions are fulfilled at lower hybrid current drive, various models of anomalous diffusion and of temperature profiles are considered. Toroidal current density profiles and related quantities are calculated, demonstrating strong dependences on the electron temperature profiles and on the effective ion charge Z_eff. Recommendations for experimental revealing the bootstrap current are presented.     

On the possible role of the bootstrap effect in the RF current drive experiments

Simple analytical relations are derived for the radial profile of the bootstrap current in a tokamak. Estimates are given for the case of both neoclassical and anomalous diffusion. The dependence of the plasma resistivity on the radial profile of the electron temperature is taken into account. The possibility of experimental revealing the bootstrap current is discussed.     

Anomalous bootstrap current estimates from experimentally found values of the radial electron transport

A method of computation of anomalous bootstrap current is suggested which uses calculated or experimentally found values of the radial transport velocity. The underlying theory is the drift kinetic equation approach of Shaing to anomalous plasma transport in a toroidal configuration and/or the MHD approach of Klíma and Petrílka to convection and diffusion in a plasma cylinder under the influence of RF fields.The author thanks R. Klíma and the referee for valuable comments.     

Currents,stress tensor and generalized unitarity in conformal invariant quantum field theory

Matrix elements of internal symmetry currents and energy momentum density tensor are constructed in Migdal Polyakov conformal invariant bootstrap field theory. Their 3-point functions satisfy Bethe Salpeter equations which determine any free coefficients that may still occur in the conformal invariant Ansatz. Ward identities are verified for alln-point functions. They imply correct equal time current commutation relations. A proof of generalized unitarity is also given. Various equivalent forms of the propagator bootstrap are discussed. Our algebraic techniques also yield an eigenvalue equation for first order correction to the exactly conformal invariant theory, assuming the latter is Gell-Mann Low large momentum asymptote of a renormalizable finite mass theory.     

Does the XY model have an integrable continuum limit?

The quantum field theory describing the massive O(2) non-linear sigma-model is investigated through two non-perturbative constructions: the form factor bootstrap based on integrability and the lattice formulation as the XY model. The S-matrix, the spin and current two-point functions, as well as the 4-point coupling are computed and critically compared in both constructions. On the bootstrap side a new parafermionic super selection sector is found; in the lattice theory a recent prediction for the (logarithmic) decay of lattice artifacts is probed.     

Bootstrap current fraction scaling for spherical torus plasmas

Dependence of the bootstrap current fraction of spherical torus plasma on the aspect ratio and the triangular deformation is studied by using a simple equilibrium model, the Solov‘ev-type equilibrium. Two bootstrap current models are used: one is the single-ion collisionless regime model, the other is the recently developed arbitrary collisional regime model. It is found that besides the well known favourable effect of the small aspect ratio on the enhancement of the bootstrap current fraction, the triangularity is beneficial for raising the total bootstrap current though it does not change its fraction much.     

Hawking Radiation from NUT Kerr Newman Kusuya Black Hole via Effective Action and Covariant Anomalies

Using the theory of the anomalous (chiral) effective action and covariant anomalies method, the Hawking radiation from NUT-Kerr-Newman-Kusuya black hole is researched. In this paper, the electric charge parameter and magnetic monopole parameter are rewritten as equivalent parameter. In addition, we simplify the metric as 1+1 dimensional effective metric. Finally, with the method of anomalous effective action and covariant anomalies respectively, we calculate the chiral covariant current and covariant energy-momentum tensor.     

Energy bands in the presence of an external force field—II Anomalous velocities

The theory of field-modified energy bands is extended to include the effect of weak scattering forces on the energy band structure. The modified current operator is found to contain terms giving anomalous currents of a type previously treated by and (Phys. Rev. 95, 1154 (1954) in connection with electrical conduction in ferromagnets. The physical meaning of these currents is discussed, and they are shown to be analogous to spin-dependent currents in Dirac's theory of the electron. They may be regarded formally as resulting from a non-commutability of the components of the coördinates. It is shown that such currents, proportional to the acceleration, are caused by every accelerating mechanism, including scattering mechanisms. A classical transport theory including the anomalous currents is derived, valid for scattering mechanisms for which the momentum transfer per collision is small, and a very simple problem carried through by way of example. A formal theory including the anomalous transport currents is given for the general case of arbitrary scattering mechanism and overlapping bands. Finally, a critique is given of some recent theories of the spontaneous Hall effect in ferromagnetics.