EAST中性束注入快离子损失研究

利用经典导心轨道程序ORBIT,结合平衡程序EFIT和输运程序TRANSP,计算了EAST中性束注入后快离子的损失情况.结果表明,4MW(80keV)氘离子的损失份额为29％,2MW(50keV)氘离子的损失份额为31％,损失的快离子有很强的局域性.     

托卡马克中局域磁扰动引起的高能量离子损失研究

基于单粒子导心运动代码ORBIT，采用测试粒子模拟方法，研究了托卡马克等离子体内部不同径向位置处局域磁场扰动对高能量离子的损失的影响。研究表明，在局域磁扰动主要分布在某磁面附近、其环向具有类似纹波场形式下，可造成一些靠近等离子体中心区域的高能量离子损失，但对靠近等离子边界的离子损失影响相对不大。这些损失的高能量离子均为捕获离子，离子的投掷角越大就越容易损失。此外，造成高能量离子最大损失率的局域场径向位置与这些损失离子的初始径向位置通常存在一定的偏移，而且这个偏移与这些离子的能量密切相关。当局域场出现在某些位置时，能量较低的离子会有一定的损失，能量较高的离子反而不会损失。     

蓝宝石的近边精细结构和电子数布居分析

利用透射电子显微镜的电子能量损失谱研究了蓝宝石AlL和OK近边精细结构，给出了Al原子和O原子的电子数布居分析及不同分截面的比较.通过考虑一个原子在均匀固体中的电离来解释近边电离区中的元素效应.应用推广的Hückel分子轨道理论及反映了晶体变换对称性影响的布洛赫定理来计算电子从内层向价层的跃迁，从而解释了近边区域的化学效应.还考虑了附加的化学效应，这来自激发原子附近的原子产生的外行平面波弹性后向散射，由此产生电离区中的所谓延展精细结构.理论计算结果与实验得到的蓝宝石单相区电子能量损失谱符合较好. 关键词：     

垂直电磁场中He原子的吸收谱和回归谱的理论计算

半经典闭合轨道理论已经成功地计算了在外加磁场和平行电磁场中的里德堡原子的回归谱.但对于垂直电磁场中的里德堡原子,理论和计算都变得更为复杂.本文把闭合轨道理论推广到三维情况,采用 B.Hüpper的模型势计算了ε=-0.03,主量子数n≈ 40,m=0下He原子在垂直电磁场中的光吸收谱和回归谱,并和H原子在垂直电磁场中的回归谱作比较,突出了实散射的贡献.计算中应用了离子实散射的分区自洽迭代方法,并考虑到轨道的多次重复和离子实的多次散射效应.这是对闭合轨道理论的验证和进一步推广.     

考虑二维效应和相对论效应时低杂波电流驱动部分模拟结果

本文介绍低杂波电流驱动模拟计算编码中福克－普朗克方程的数值求解。考虑了螺距角散射造成的高垂直温度效应（二维效应）和相对论效应。同时．福克－普朗克方程中包括了描述尾部电子约束的项。数值结果表明，二维效应和相对论效应的加入均能提高电流驱动效率。驱动电流随尾部电子约束改善而增加。     

MPT-X装置电源回路的计算及实验

磁约束聚变实验装置的一个重要问题是它的各个磁场线圈的放电回路的设计.MPT-X装置是进行托卡马克运行和多极器混合位形运行的装置,产生的磁场包括纵场、加热场、平衡场和八极场.各个磁场所采用的电源都是由储能电容器组、引燃管开关和线圈组成的RLC放电回路. 我们编制了一个通用程序,包括自感、互感和电阻的计算,电压和电流的波形计算,并附有绘图子程序,使用方便、快速.该程序适用于由多组轴对称线圈组成的放电回路分析. 使用罗柯夫斯基线圈对各放电电流进行了测量,实验结果和理论计算值相符. 一、方 程 纵场的方向与其它场是正交的,可…     

托卡马克中带电粒子的直接损失问题研究

首次发现了托卡马克中存在迥异于通行粒子和香蕉粒子的第三种粒子, 这种粒子会由于漂移运动而摆脱磁场的约束. 研究了该类粒子在其速度空间上的类磁镜损失锥, 给出了这一损失锥的数学表达式, 分析了存在这一类粒子的物理成因, 模拟与数学分析的结果基本一致. 研究还发现, 回旋半径在二阶条件下带电粒子的轨道损失高于零阶情况, 且与装置参数密切相关.     

铁磁-d波超导结中的粗糙界面散射和自旋反转效应对隧道谱的影响

考虑到铁磁层中的自旋极化效应、以及界面的粗糙散射和自旋反转效应,利用推广了的Blonder Tinkham Klapwijk理论模型,计算铁磁d波超导结中的自旋极化隧道谱.研究表明1)自旋反转效应能使零偏压电导峰变得尖锐;2)粗糙的界面散射除了能压低零偏压电导峰的高度,还能使零偏压凹陷处感应出一中心峰.结果能定性地解释最近的两篇关于La_2/3Ba_1/3 MnO₃/DyBa₂Cu₃O_{7关键词： 自旋极化效应 自旋反转效应 粗糙界面散射效应 隧道谱}     

平行电磁场中He+2的回归谱与闭合轨道的研究

利用半经典闭合轨道理论和分区自洽迭代方法计算了Rydberg态下He⁺₂在平行电磁场中的回归谱与闭合轨道. 为了模拟分子实的散射作用,引入一个包含电子交换势的新势能. 利用这一新势能,结合多通道量子亏损和分子闭合轨道理论,讨论了分子实散射效应对平行电磁场中He⁺₂的回归谱与闭合轨道的影响. 关键词： 回归谱 分子半经典闭合轨道 交换势 实散射     

低速分子离子在固体电子气中的散射与能量损失

利用量子力学中的电子分子散射理论，研究了低速双原子分子离子在固体电子气中的散射与能量损失，重点讨论了两离子之间的干扰效应对能量损失的影响。根据原子的ｉｎｄｅｐｅｎｄａｎｔ ｐａｒｔｉｃｌｅ－ｍｏｄｅｌ（ＩＰＭ）势和变相法，确定了单原子离子的散射相移和阻止本领，并与非线性密度泛函理论的结果进行了比较。 关键词：     

Numerical study of fast ion behavior in the presence of magnetic islands and toroidal field ripple in the EAST tokamak

A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.     

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Based on ORBIT code of a guiding center motion of single particle, the loss of energetic ions in different radial positions of tokamak plasma is studied by using test particle simulation method. The results show that the local magnetic perturbations can cause loss of many energetic ions near the central region of the plasma, but they have little effect on the ion loss near the plasma boundary, assuming that the local field is mainly located near a magnetic surface and its toroidal field is similar to the ripple field. These energetic ions are trapped ions, and the greater their pitch angle is, the easier they lose. In addition, the radial position of the local field that causes the maximum loss rate of energetic ions is usually offset from the initial radial position of these loss ions, and this shift is closely related to the energy of these ions. When the local field appears in certain locations, the ions of lower energy have some loss, but the ions higher energy does not lose.     

Observation of weak impact of a stochastic magnetic field on fast-ion confinement

Fast ions are observed to be very well confined in the Madison Symmetric Torus reversed field pinch despite the presence of stochastic magnetic field. The fast-ion energy loss is consistent with the classical slowing down rate, and their confinement time is longer than expected by stochastic estimates. Fast-ion confinement is measured from the decay of d-d neutrons following a short pulse of a 20 keV atomic deuterium beam. Ion confinement agrees with computation of particle trajectories in the stochastic magnetic field, and is understood through consideration of ion guiding center islands.     

Dynamics of magnetic vortices

The canonical conservation laws of linear and angular momentum in the ferromagnetic continuum have been known to be plagued by certain ambiguities which are resolved in this paper by constructing conservation laws as suitable moments of a topological density. The resulting canonical structure is then shown to be analogous to that encountered in the familiar Hall effect and explains the unusual features of the dynamics of magnetic vortices without resorting to a detailed solution of the underlying nonlinear equations. Thus, in the absence of external magnetic fields, a magnetic vortex is shown to be spontaneously pinned around a fixed guiding center. The guiding center would drift in a direction perpendicular to an applied magnetic field gradient, provided that dissipation can be neglected, with a Hall velocity that is calculated explicitly in terms of the initial configuration of the vortex. In the presence of dissipation, the vortex undergoes skew deflection at an angle δ ≠ 90° with respect to the applied field gradient. The angle δ is related to the winding number of the vortex according to the well-known golden rule of bubble dynamics.     

反向场位形下的引导中心哈密顿函数

本文给出了反向场位形中场反向处引导中心哈密顿函数。在零级磁场线性近似下给出粒子运动及引导中心位置的精确解,分析了解的特性。小磁场注向分量对引导中心哈密顿函数的贡献由李变换方法求取。最后讨论了该哈密顿函数的性质并和数值结果作了比较。该理论可以用来研究带电粒子在行星际空间电流片、磁尾中性片以及实验室中反向场箍缩中的运动特性。     

识别TdeV托卡马克等离子体的边界和中心位置

用虚壳原理可以得到TdeV托卡马克等离子体边界、电流中心和X点,用最小二乘法可以确定Glad-Shafranov方程解中的待定参数。用探针测量极向磁场,初始时等离子体电流被看作是线电流,然后被虚壳电流代替。这个虚壳电流在等离子体内部产生负的约束磁场,在等离子体外部产生的磁场与等离子体电流产生的磁场一致,所用的叠代法充分快,可以在两次放电间给出等离子体图象,重建的位形与TV成像非常一致。     

东方超环上低杂波驱动等离子体环向旋转实验研究

旋转和旋转剪切能抑制磁流体不稳定性和增强等离子体约束.低杂波电流驱动作为未来聚变堆上可能的旋转驱动手段,探索低杂波在现有托卡马克装置上驱动等离子体旋转的驱动机制,可以为未来的聚变堆上旋转预测提供重要参考.在东方超环托卡马克装置上,早期发现了2.45 GHz的低杂波能有效驱动等离子体旋转的现象,认为是边界旋转的改变导致芯部旋转的同电流方向的增加造成的.更高频率下4.6 GHz低杂波电流驱动可以更有效地驱动同电流方向的等离子体旋转.本论文分析在欧姆背景等离子体下,不同功率的低杂波对等离子体环向旋转的影响,研究安全因子剖面变化对环向旋转的关系,利用功率调制获得了低杂波驱动旋转实验中的环向动量输运系数变化情况,发现环向动量扩散系数(χφ)、环向动量箍缩系数(Vpinch)的数值大小趋势是从芯部向靠外的区域逐渐变大.这与低杂波驱动环向旋转时,环向旋转速度由靠外的区域向芯部传递的特性吻合.     

Multipolar Structure of Equilibrium Shear Flow Field in Toroidal Plasmas

The multipolar velocity field structures are investigated by 2D momentum conservation equation with 3D equilibrium sheared flows in the full toroidal system. Numerical results show that the non-existence of radial velocity field in equilibrium surfaces is suitable only for the zero-order term of our 2D simulation. The non-zero-order radial velocity field is still preserved, even when converted to conventional magnetic surface coordinates. The distribution of velocity field vectors of the order of 1, 2, and 3 are presented respectively in 2, 4, and 6 polar fields with the local vortex structure. The excitation mechanisms of these velocity vortices are the coupling effects of the magneto-fluid structure patterns and the toroidal effects. These results can help us understand the complexity of core physics, the transverse transport across magnetic field by the radial plasma flow and the formation of velocity vortices.