共查询到20条相似文献,搜索用时 15 毫秒
1.
A code named LARWM with non-ideal magnetohydrodynamic equations in cylindrical model is used to describe the instability in Tokamak plasma surrounded by a conducting wall with finite resistivity. We mainly take three factors related to the shear equilibrium plasma flow into consideration to study the stabilizing effect of the shear flow on the resistive wall modes (RWMs). The three factors are the velocity amplitude of flow, the shear rate of flow on plasma surface, and the inertial energy of equilibrium plasma flow. In addition, a local shear plasma flow is also calculated by the LARWM code. Consequently, it is found that the inertial energy of the shear equilibrium plasma flow has an important role in the stabilization of the RWMs. 相似文献
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求解定态薛定谔方程常常会涉及到常微分方程的本征值问题.目前解常微分方程本征值用的比较多的方法是以龙格-库塔方法为基础的打靶方法.打靶方法常用,但是计算时间长.当边界条件比较复杂或比较敏感的时候,用松弛法会有更好的效果.本文用松弛法解薛定谔方程,并和理论解进行比较.发现松弛法得到的数值解和理论解符合度很高,而且使用松弛法... 相似文献
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介绍了基于“平衡重建”反演模式的在线分析与在线显示平台EFIT。通过基于套接字(socket)的异构平台通信机制,实现了不同平台间的大数据量传输。用有限状态机描述服务端来管理节点,用群集系统的若干工作节点实现并行化计算,完成整个放电过程的位形重建通常只需要约1min的时间,能够满足(等离子体放电)间隔期间“在线显示等离子体平衡位形”的要求。利用该异构平台间通信模型,可将Linux平台下EFIT的运行结果,在Windows环境中在线地分析利用。 相似文献
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The central problem of the lattice Boltzmann method (LBM) is to construct a discrete equilibrium. In this paper, a multi-speed 1D cell-model of Boltzmann equation is proposed, in which the cell-population equilibrium, a direct non- negative approximation to the continuous Maxwellian distribution, plays an important part. By applying the explicit one-order Chapman-Enskog distribution, the model reduces the transportation and collision, two basic evolution steps in LBM, to the transportation of the non-equilibrium distribution. Furthermore, 1D dam-break problem is performed and the numerical results agree well with the analytic solutions. 相似文献
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The central problem of the lattice Boltzmann method (LBM) is to
construct a discrete equilibrium. In this paper, a multi-speed 1D
cell-model of Boltzmann equation is proposed, in which the
cell-population equilibrium, a direct non-negative approximation to
the continuous Maxwellian distribution, plays an important part. By
applying the explicit one-order Chapman--Enskog distribution, the
model reduces the transportation and collision, two basic evolution
steps in LBM, to the transportation of the non-equilibrium
distribution. Furthermore, 1D dam-break problem is performed and the
numerical results agree well with the analytic solutions. 相似文献
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Relative populations of the excited levels for Cr(I), Cr(II), Fe(I) and Fe(II) in the argon plasma flow of an arc two-jet
plasma generator used in spectrochemical analysis were measured. The range of the total energy E of excitation and ionization
was 4.5–8.0 and 12.5–16.0 eV, respectively. It is shown that the populations of atom and ion levels are linear with respect
to energy lower than E∼15 eV. For ionic lines with energy close to 15.5–16.0 eV the line intensities behave anomalously against
equilibrium values. This can be associated with charge transfer between the analyte and argon ions. Deviation of I from LTE
values increases in the plasma zones below and above the site of jet confluence, where the plasma temperature decreases.
A. P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, 1a Favorskii St., Irkutsk,
664033, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 575–581, September–October, 1997. 相似文献
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光学透过性能对信号微弱的激光汤姆逊散射测量系统极为重要。主要讨论了HT-7 Nd:YAG激光汤姆逊散射系统光学设计中消除杂散光和提高散射信号传输效率的方法,并对系统的光学性能进行了模拟计算。模拟结果显示,干涉滤光片分光谱仪的光学透过性能随电子温度的升高而增强,等离子体电子温度为1 keV时其透过率可达到10%;汤姆逊散射信号非常微弱,等离子体电子密度为1×1019/m3时每道信号仅有几百到上千个光子;等离子体电子温度在0.3~5.0 keV范围内时,光子量子统计涨落引起的电子温度测量误差在3%以下。 相似文献
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The present contribution tries to find a scientific answer to the question of stability of an equilibrium plasma sheath in
a colloidal plasma system under external gravity effect. A model equilibrium of hydrodynamical character has been discussed
on the basis of quasi-hydrostatic approximation of levitational condition. It is found that such an equilibrium is highly
unstable to a modified-ion acoustic wave with a conditional likelihood of linear driving of the so-called acoustic mode too.
Thus, it is reported (within fluid treatment) that a plasma-sheath edge in a colloidal plasma under external gravity effect
could be highly sensitive to the acoustic turbulence. Its consequential role on possible physical mechanism of Coulomb phase
transition has been conjectured. However, more rigorous calculations as future course of work are required to corroborate
our phenomenological suggestions. 相似文献
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Limiters play a number of roles in the tokamak operation. It serves primarily to protect the wall from the plasma when there are disruptions, runaway electrons, or other instabilities and also the limiters localize the plasma–surface interaction. In this research, we presented the first results of movable limiter experiments and its effects on the tokamak plasma confinement. For this purpose, we designed, constructed, and installed a movable localized poloidal limiter, and then measured the effects of limiter position on the time intervals of plasma parameters such as plasma density, temperature, and energy confinement time. The results of effects of the movable limiter experiments on plasma confinement. 相似文献
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Suter A Mali M Roos J Brinkmann D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,143(2):266-273
We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin–lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a Δm = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-echo experiment. We calculated analytically this intensity change for spins I = 1,
,
, thus providing a quantitative analysis of the experimental results. Since the pulse sequence we used takes care of the absorbed radiofrequency power, no problems due to heating arise. The method is especially suited when only one NMR sensitive isotope is available. Different cross-checks were performed to prove the reliability of the results obtained. The applicability of this method is demonstrated by a study of the plane oxygen 17O (I =
) in the high-temperature superconductor YBa2Cu4O8: the 17O spin–lattice relaxation rate consists of magnetic as well as quadrupolar contributions. 相似文献
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针对螺线管磁轴测量中的悬丝位置、测量信号失真、磁轴偏轴和磁轴倾斜信号的分离数据处理要求等问题,采用一种高偏置消除的信号检测与测量方法,并对探测器采用了相关的恒定驱动技术,进一步提高了信号产生的稳定性及抗干扰能力,研制了一种可以获得比较直接的悬丝振动信号的测量系统,解决了单纯采用交流耦合隔直滤波放大器或带通滤波放大器不能获得完全准确的测量信号的问题,确保了在较高的直流偏置下获得没有畸变的较小测量信号,消除了测量信号中低频分量基线倾斜及其中起伏的影响,并实现了磁轴偏移和磁轴倾斜信号的分离,极大地提高了螺线管线圈磁轴的测量灵敏度,实际测试结果显示测量灵敏度提高约1个量级。 相似文献
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An interpolation inequality for the total variation of the gradient of a composite function is derived by applying the coarea formula. A bound for the pressure integral is studied by establishing ana priori estimate for a solution of the Grad-Shafranov equation of plasma equilibrium. A weak formulation of the Grad-Shafranov equation is given to include singular current profiles. 相似文献
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基于表面阻抗边界条件时域有限差分(FDTD)方法研究了一维斜入射情况下非磁化等离子体薄涂层涂敷金属材料的电磁散射特性, 该方法忽略对薄层背景材料进行网格剖分, 大大减少了计算量. 首先推导了理想导体涂敷等离子体薄涂层的表面阻抗频域表达式, 然后代入边界条件并变换到时域, 再用分段线性递推卷积方法将时域表达式离散得到FDTD迭代式. 编程计算了垂直及斜入射情形下的平行极化和垂直极化反射系数, 通过验证算例与解析解对比, 结果表明该方法的准确性和有效性. 最后利用该方法分析了不同入射角对反射系数的影响. 相似文献
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光电极值法是光学薄膜厚度监测的常用方法,该方法在镀膜前引用块状材料的折射率设计膜系。而在实际镀制过程中,用于镀制光学薄膜的材料折射率会发生改变,从而给膜厚的监控带来误差。为了避免折射率变化的影响,采用外差干涉法测量折射率,将实际测得的薄膜折射率应用光电极值法监控薄膜的设计,从而减少了因材料折射率的变化引起的误差。以750nm截止滤光片的镀制为被测对象进行了实验,对制备的滤光片透射率光谱曲线进行了比较。结果表明,实际的透射率曲线与设计的透射率曲线吻合较好,两次实验曲线平均吻合度均在98%以上,系统稳定性很好,从而说明结合外差干涉法的光电极值监控法可以很好地克服折射率变化引起的误差。 相似文献
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基于面积差弹性模型, 用弛豫法探寻满足开口膜泡边界条件的欧拉-拉格朗日方程组的新解, 得到了双开口的哑铃形分支解, 并结合以前得到的单开口哑铃形及闭合哑铃形, 对它们之间的相变进行了深入的研究. 为了探究实验上是否可能发现这些形状, 与以往实验上观察到的较小约化弛豫面积差的杯形、管形、烟囱形开口形状的能量进行了比较, 发现这些新形状在较大的约化弛豫面积差值时, 在某些线张力区间比以往发现的形状能量更低. 另外为了对比, 本文对于实验上已知的杯形、管形、烟囱形及球形之间的相变行进行了探讨, 并对两者之间的不同特点进行了对比. 相似文献