夸克的半经典输运方程

对夸克的量子输运方程取半径典近似时保留到Wigner函数的一次微商项;在色空间和自旋空间展开这个半经典输运方程,得到了色单态自旋标量和色单态自旋矢量的输运方程:并把得到的结果和阿贝尔等离子体进行比较讨论了QGP的非阿见尔性质.     

非阿贝尔介质对外源的非线性响应方程

从动力论理论出发,使用弱湍理论方法,有效地展开了夸克–胶子等离子体的动力论方程,从而给出了夸克–胶子等离子体介质对外流的非线性非阿贝尔响应方程。     

QGP中胶子的经典输运方程

建立了夸克胶子等离子体中胶子的经典输运方程, 并讨论了它与胶子的量子输运方程以及它与夸克的经典输运方程之间的关系.     

在弛豫时间近似下QGP中夸克输运系数的一种计算

从动力论方程出发,考虑QGP中平均场效应,采用弛豫时问近似,给出了关于QGP输运系数的一种分析方法,推导出QGP中夸克输运系数解析式,讨论了QGP粘滞效应与导热效应.     

胶子非弹性散射过程对夸克胶子等离子体中双轻子产生的影响

双轻子是研究夸克物质的形成和性质的重要探针.本文基于化学平衡化的黏滞性夸克胶子等离子体演化模型,计算了相对论重离子碰撞能量下金-金对心碰撞形成的夸克胶子等离子体中的双轻子产额.在黏滞性计算中加入了胶子非弹性散射过程对黏滞系数的贡献.相较仅考虑夸克和胶子弹性散射的情况,双轻子的产额有较明显的降低.这表明在黏滞系数中加入胶子非弹性散射的贡献使得系统的演化过程加快,演化时间变短.     

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用密度调制的方法研究了等离子体中粒子输运问题。采用了注入脉冲式补充送气和超声分子束两种不同的密度调制方法。在HL-2A装置常规欧姆放电的情况下,运用有限差分法和Nagashima矩阵技术,求解了粒子平衡方程。计算出了粒子的输运系数(对流速度v和扩散系数D)。研究了粒子输运系数与等离子体线平均密度之间的关系。实验结果表明,在欧姆放电的情况下,等离子体芯部的粒子对流速度方向始终是向内的,并且密度低时,粒子输运系数(粒子扩散系数D和对流速度v)较大;密度高时,粒子输运系数较小。     

氩-碳-硅等离子体热力学性质和输运系数计算

计算了广温度范围(300—30000 K)和广压力范围(0.1—10 atm, 1 atm=101.325 k Pa)下,不同混合物比例、碳和硅蒸气浓度的局域热力学平衡(LTE)和化学平衡(LCE)的氩-碳-硅等离子体组分、热力学性质和输运系数.等离子体气相平衡组分使用质量作用定律计算,同时凝聚相组分采用相平衡的方法计算.输运系数的计算包括黏度、电导率和热导率,使用拓展到高阶近似的Chapman-Enskog方法.采用文献中较新的数据得到了较为准确的碰撞积分,导出了Ar-C-Si等离子体的输运系数.结果表明,在相变温度以下,凝聚态物种的引入导致Ar-C-Si等离子体的热力学性质、输运系数与纯Ar等离子体接近,在相变温度点则会产生不连续点.压力、碳/硅蒸气浓度和比例对等离子体热力学性质和输运系数具有较大影响.最终计算值与文献数据对比符合良好,有望为氩-碳-硅等离子体传热流动数值模拟提供基础数据.     

HL－1托卡马克杂质注入实验及杂质输运特性的研究

本文给出了ＨＬ－１托卡马克在通常欧姆放电和偏压诱发Ｈ模放电条件下，脉冲注入杂质气体的实验结果以及对杂质在通常欧姆等离子体和偏压诱发Ｈ模等离子体中的输运研究结果。实验结果表明，在ＨＬ－１上偏压诱发Ｈ模等离子体中对杂质的约束性能明显优于在通常欧姆等离子体中对杂质的约束性能。杂质输运的数值模拟结果说明，无论在通常欧姆等离子体中，还是在偏压诱发Ｈ模等离子体中，杂质的输运系数都比新经典理论预计的要大得多，输运是反常的。在偏压诱发的Ｈ模等离子体中引入杂质输运“位阱”概念，能够对杂质离子约束时间长的实验现象进行很好的描述。合理地解释了在偏压杂质注入实验中杂质辐射上升时间长、衰减慢的现象。     

流注放电低温等离子体中电子输运系数计算的蒙特卡罗模型

流体或者粒子-流体混合数值仿真是研究流注放电基本物理机制的常用手段,而精确的电子输运系数是保证其仿真正确性的必要前提.鉴于现有电子输运系数求解工具存在一定缺陷,本文开发了采用蒙特卡罗方法求解低温等离子体中电子输运系数的仿真工具,测试表明其准确性和精确度均较高.研究了氮氧气体混合比及大气压下三体碰撞吸附对电子输运系数的影响.氮气中流注放电仿真表明,流体仿真中采用本模型改进后的电子输运系数可显著改善流注通道内部的等离子体参数分布.     

低混杂波电流驱动下注入杂质的输运

在欧姆放电和低混杂波电流驱动条件下,应用激光吹气技术注入金属杂质,用真空紫外谱仪测量了杂质线的辐射,给出了ＨＬ－１Ｍ 装置欧姆等离子体和低混杂波电流驱动等离子体杂质输运的研究结果。用杂质输运程序ＬＢＯ进行数值模拟,得出了等离子体中杂质的扩散系数Ｄ（ｒ） 和对流速度ｖ（ｒ）。在低混杂波电流驱动条件下,等离子体杂质的输运系数相对欧姆放电等离子体杂质的输运系数减小了５０％ 左右。结果表明,在ＨＬ－１Ｍ 装置上低混杂波电流驱动等离子体相对通常欧姆等离子体杂质的约束性能明显得到了改善     

New bipartition model of neutral particle transport in the HL-2A divertor region

A new bipartition neutral transport model has been developed for simulation of the hydrogenic neutral particle transport in the vicinity of HL-2A divertor target plate. The numerical calculation results on the basis of this model are fairly consistent with the results obtained with the “multi-generation method”. One possible application of this model is to provide a source term originating from neutral transport calculation for any other edge plasma transport code, for instance, B-2 code, which has been used to simulate edge plasma transport of the HL-2A divertor configuration. Especially it can be utilized to quickly classify the plasma in divertor region as high or low recycling regime.     

Optical studies of fast plasma transport in Si

We present two new optical techniques for the investigation of the transport properties of ambipolar plasmas in semiconductors. The first method is a time-of-flight technique: Using surface doping with shallow impurities which provide a characteristic bound exciton emission we introduce optically active spatial markers into the thin Si wafers investigated. Carrier pairs are excited at the undoped surface of the wafer by short laser pulses. From time-resolved studies of the bound exciton emission we obtain average velocity values for the ambipolar transport through the sample. The most attractive feature of the time-of-flight method compared to other spatially resolved measurements is the combination of very high spatial resolution (submicron range) with a high sensitivity. The second method used to study the plasma transport is based on a time-resolved investigation of the Mott transition between the electron-hole plasma and free excitons in Si. Using well-established values for the Mott transition and the temporal evolution of the plasma and the free exciton emissions we obtain values for the velocity with which the plasma expands to the Mott density as functions of the excitation power and the temperature. The advantage of this method is the lack of any need for spatial resolution. Possible extensions of both methods are discussed.     

氙等离子体输运性质计算

采用基于将Chapman-Enskog方法扩展到高阶近似的方法计算获得了温度范围在300—40000 K,不同压力条件下氙等离子体的黏性、热导率和电导率.热力学平衡条件下的计算结果与文献报道的实验和计算结果符合良好,验证了计算方法和结果的合理性与准确性.在此基础上,计算获得了电子温度(T e)不等于重粒子温度(T h)的热力学非平衡和化学平衡条件下氙等离子体的输运性质,并分析了输运性质随压力和热力学非平衡程度变化的原因.     

双温度氩-氮等离子体热力学和输运性质计算

获得覆盖较宽温度和压力范围内的等离子体热力学和输运性质是开展等离子体传热和流动过程数值模拟的必要条件.本文通过联立Saha方程、道尔顿分压定律以及电荷准中性条件求解等离子体组分;采用理想气体动力学理论计算等离子体热力学性质;基于Chapman-Enskog方法求解等离子体输运性质.利用上述方法计算了压力为0.1, 1.0和10.0 atm (1 atm=101325 Pa),电子温度在300—30000 K范围内,非局域热力学平衡(电子温度不等于重粒子温度)条件下氩-氮等离子体的热力学和输运性质.结果表明压力和非平衡度会影响等离子体中各化学反应过程,从而对氩-氮等离子体的热力学及输运性质有较大的影响.在局域热力学平衡条件下,计算获得的氩-氮等离子体输运性质和文献报道的数据符合良好.     

Transport properties of high temperature air in local thermodynamic equilibrium

In the paper new calculated transport coefficients of air in the temperature range 50-100 000 K are presented. The results have been obtained by means of the perturbative Chapman-Enskog method, assuming that the plasma is in local thermodynamic equilibrium (LTE). The calculations include viscosity, thermal conductivity, electric conductivity and multicomponent diffusion coefficients. For the calculation, a recent compilation of collision integrals obtained by Capitelli et al. [1] has been utilized. Analytical expression for all transport coefficients and thermodynamic parameters of the air plasma are also reported. Received 17 November 1999     

双温度氦等离子体输运性质计算

获得覆盖较宽温度和压力范围内的等离子体输运性质是进行等离子体传热和流动过程数值模拟的必要条件.本文采用Saha方程计算等离子体组分, 采用基于将Chapman-Enskog方法扩展到高阶近似的方法, 计算获得了电子温度(T_e)不等于重粒子温度(T_h)的情形下, 在300 K到40000 K的温度范围内氦等离子体的黏性、热导率和电导率. 研究结果表明压力和热力学非平衡参数(θ =T_e/T_h)对氦等离子体的输运性质有较大的影响. 在局域热力学平衡条件下,计算获得的氦等离子体输运性质和文献报道的数据符合良好.     

Radial transport dynamics studies of SMBI with a newly developed TPSMBI code

In tokamak plasma fueling, supersonic molecule beam injection(SMBI) with a higher fueling efficiency and a deeper penetration depth than the traditional gas puffing method has been developed and widely applied to many tokamak devices.It is crucial to study the transport dynamics of SMBI to improve its fueling efficiency, especially in the high confinement regime. A new one-dimensional(1D) code of TPSMBI has also been developed recently based on a six-field SMBI model in cylindrical coordinate. It couples plasma density and heat radial transport equations together with neutral density transport equations for both molecules and atoms and momentum radial transport equations for molecules. The dominant particle collisional interactions between plasmas and neutrals, such as molecule dissociation, atom ionization and charge-exchange effects, are included in the model. The code is verified to be correct with analytical solutions and also benchmarked well with the trans-neut module of BOUT++ code. Time-dependent radial transport dynamics and mean profile evolution are studied during SMBI with the TPSMBI code in both slab and cylindrical coordinates. Along the SMBI path, plasma density increases due to particle fuelling, while plasma temperature decreases due to heat cooling. Being different from slab coordinate, the curvature effect leads to larger front densities of molecule and atom during SMBI in cylindrical coordinate simulation.     

Enhanced plasma transport due to neutral depletion

The dynamics of plasma and neutral gas in pressure balance are solved self-consistently to reveal the impact of neutral depletion. Analytical relations that determine the electron temperature, the rate of ionization, and the plasma density are derived. Because of the inherent coupling of ionization and transport, an increase of the energy invested in ionization can nonlinearly enhance the transport process. We show that such an enhancement of the plasma transport due to neutral depletion can result in an unexpected decrease of the plasma density when power is increased, despite the increase of the flux of generated plasma.