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利用调制送气过程中观察到的冷脉冲传播,研究了在HL-2A装置欧姆放电条件下的电子热输运。从扰动输运方程出发,分析了电子热输运过程,利用在实验中获得的数据,进行了曲线拟合和数值计算,得到了在HL-2A装置欧姆放电条件下强场侧电子热输运系数的分布特征为χ=15-14(1-r2)2m2.s-1。     

HL-2M 装置初始等离子体放电阶段的直流辉光放电清洗系统研制

基于 HL-2M 托卡马克初始等离子体放电的工程需求,设计并研制了直流辉光放电清洗系统,包括电 极、馈线、电源、控制以及监测等关键部件和辅助子系统。研制完成后开展了系统装配和工程调试,并投入到首 次等离子体放电。实验结果表明,该直流辉光放电系统运行稳定、可靠,且此辉光放电清洗显著降低了真空室本 底杂质浓度,能满足 HL-2M 装置初始等离子体放电的壁条件需求。     

HL-1装置放电清洗系统和实验

本文描述了HL-1装置的泰勒放电清洗系统和其清除氧、碳等轻杂质的能力。研究了水分压强的某些特性及其同充氢气压、等离子体电流(电子温度)、电子密度的关系。从而找到了HL-1装置的泰勒放电清洗最佳运行参数。     

用B2程序模拟HL-2A装置附着状态等离子体

用大型边缘多流体二维等离子体输运数值模拟程序B2模拟了HL-2A装置外偏滤器以及与之相连的刮削层内的等离子体。在不同的中心密度运行区，纯氢放电的HL-2A偏滤器可以形成不同的再循环运行模式，即线性或高再循环模式。通过控制模拟刮削层与芯部等离子体交界面处的等离子体参数，可实现对HL-2A装置再循环模式的控制。     

HL-2A托卡马克实验进展和科学创新

中国环流器二号A(HL-2A)托卡马克是中国第一个带偏滤器的大型受控核聚变研究装置.文章综述了在HL-2A托卡马克装置上的重要实验结果.自从HL-2A装置建成以来,有以下3个重要进展:实现了等离子体偏滤器位形放电;等离子体电子温度达到5500万度;实现了具有边缘局域模的高约束(H模)放电.随着HL-2A装置辅助加热能力和先进等离子体诊断等系统的发展,该装置在聚变等离子体物理的若干领域做出了以下创新性的贡献:实验验证了对聚变等离子体输运有重要影响的带状流的三维结构;进一步发展了原创的分子束加料技术,并且成功地应用于等离子体输运研究;用低频调制的电子回旋共振加热(ECRH)对撕裂模进行了有效的抑制,并使约束得到改善;观测到高能电子激发的内部扭曲模和阿尔芬模等新的物理现象.文章还简要介绍了该装置的发展计划及近期要开展的物理实验研究内容.     

亚辉光放电在HL—1装置的应用

本文简述亚辉光放电在HL-1装置上的应用。实验表明,这是一种安全、简便有效的清洗和碳化手段,它可以弥补磁控清洗放电和碳化的不足之处,并为HL-1M装置器壁锻炼提供了先行试验。     

HL-1装置中的相对论性非热辐射

在垂直于大半径方向用两个固定频率((?)0和(?)5GHz)的毫米波段外差接收机研究了在HL-1装置中等离子体的非热辐射。根据这些辐射与等离子体密度的关系,HL-1装置的放电可分为4种类型,并得到两个临界密度。这些辐射特性被认为是与逃逸放电性质和逃逸动力学不稳定现象有关。在实验中还观察到了与这种不稳定性有关的一系列等离子体宏观现象以及由此引起的逃逸损失。     

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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。     

HL-2A装置偏滤器室中性气体压强的初步研究

HL-2A装置上首次实现了偏滤器位形放电。采用专门研制的可在强磁场和强噪声环境下工作的快响应真空电离规对偏滤器室内的中性气体压强进行了测量,给出了HL-2A装置偏滤器有关结构的基础数据。初步研究了偏滤器位形和孔栏位形放电期间偏滤器室中性气体压强的特性。     

HL—1装置几种杂质特性

本文叙述了用真空紫外光谱方法观测HL-1装置常规、器壁碳化和抽气孔栏三种放电条件下等离子体杂质的变化以及某些杂质的特性。     

第一性原理计算绝缘体-金属转变临界掺杂浓度:Co重掺杂Si体系

基于密度泛函理论的第一性原理方法,本文旨在探索确定绝缘体-金属转变临界浓度的理论计算方法.以Co重掺杂Si为研究对象,构建并计算了10个Co不同掺杂浓度模型的晶体结构、杂质形成能及其电子性质.发现在Co掺杂Si体系的带隙中形成了杂质能级,杂质能级的位置和宽度随着Co浓度的增加呈线性变化.当Co掺杂浓度较高时杂质形成能逐渐稳定,且杂质能级穿过费米能级使体系表现出金属性.综合杂质形成能的变化趋势,以及杂质能级极小值与费米能级间的距离条件,可预测出发生绝缘体-金属转变的Co掺杂浓度为2.601Wingdings 2MC@10~(20) cm~(-3),与实验结果相一致.上述两条依据应用于S重掺杂Si体系和Se重掺杂Si体系同样成立.     

ZnS掺Mn的电子结构研究

 用自旋极化的LSD-LMTO（Local-Spin-Density Linear Muffin-Tin-Orbital Method）方法，对ZnS掺入Mn发光中心的电子结构进行了大型超原胞模拟计算。在自洽收敛的条件下，先对纯ZnS调节计算参数（原子球、空球占空比），使计算的带隙E_g=3.23 eV；然后用原子球替代方式自洽计算杂质密度在E_g中的相对位置，模拟计算了在六角结构ZnS中掺入不同浓度的Mn杂质后有关的杂质能级在E_g中的相对位置。计算结果表明：（1）单个缺陷的杂质能级性质与配位场理论结果相符合，直接用杂质态密度来表示；（2）掺入杂质的浓度对杂质能级位置的影响不大，这与实验结果相一致。     

一种低温气体分离回收方法研究

介绍了一种适合于分离氦气中微量Kr、Xe、H2及其同位素的方法。对比了不同分离方法的特点,并最终采用低温分凝法来分离混合气体。设计了分离的流程及温度、压力等物理参数,通过分析和计算,确定了在合适温度下,可以分离提取出混合气体中的杂质气体,实现最终尾气中杂质气体所要求的浓度指标。并得出最终混合气体杂质浓度只与进气压力和冷冻温度有关的结论。     

Measurement of impurity concentration in chalcogenide glasses using optical principle

Owing to impurity concentration, is important in chalcogenide glass to study various commercial applications, this paper presents a novel technique to measure the impurity concentration in chalcogenide glass at wavelength of 633 nm and 1500 nm using optical principle. Here both reflection and absorption losses are considered to estimate the same impurities. Reflectance is found using plane wave expansion method, where absorption factor is determined using Maxwell's curl equations. Simulation result reveals that reflectance, absorption factor and transmitted intensity vary linearly with respect to different impurity concentrations. The excellent linear variation of transmitted intensity gives an accurate measurement of impurity concentration in chalcogenide at aforementioned wavelength.     

应变Si1-xGex层中p型杂质电离常温和低温特性

本文采用解析的方法计算了应变Si1-xGex层中p型杂质电离度与Ge组分x、温度T以及掺杂浓度N的关系.发现常温时,在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度的先变小,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加先变大,而后几乎不变;重掺杂时,杂质电离能变为0后,杂质电离度为1.低温下,轻掺杂时,载流子低温冻析效应较为明显,杂质的电离度普遍较小,当掺杂浓度大于Mott转换点时,载流子冻析效应不再明显,电离率迅速上升到1.在同一Ge组分下,随着掺杂浓度的升高,杂质的电离度先变小,后变大,而后又迅速上升到1.在同一掺杂浓度下,轻掺杂时,杂质的电离度随Ge组分的增加变大;重掺杂时,杂质电离能变为0后,杂质电离度为1.     

单壁碳纳米管杨氏模量的掺杂效应

用分子动力学方法研究了N,O,Si,P,S等5种杂质对扶手椅型(5，5)和锯齿型(9，0)单壁碳纳米管杨氏模量的影响.结果表明：直径为0.678和0.704 nm的扶手椅型(5，5)和锯齿型(9，0)碳纳米管在无掺杂时其杨氏模量分别为948和804 GPa.在掺杂浓度10％以下，碳纳米管的拉伸杨氏模量均随掺杂浓度增加近似呈线性下降规律，下降率以Si掺杂最大，N掺杂最小.对与C同周期的元素掺杂，随原子序数增加碳纳米管的杨氏模量下降率增大；与C不同周期的元素掺杂，碳纳米管的杨氏模量随掺杂浓度增加下降率更大，但 关键词： 碳纳米管 杂质 杨氏模量 分子动力学方法     

Classical Advection-Diffusion in Heterogeneous Media

A method is proposed for solving the problem of impurity transport in heterogeneous medium due to the classical diffusion and advection. The case when advection is absent was analyzed separately. It focuses on distances from the impurity source, which are much larger than the main body of its localization, and the asymptotic approach developed by one of the authors (P.S.K.) is used. The problem is reduced to solving a differential equation of the first order, which determines the linear trajectory of the concentration signal from the source that arises with this approach to the point of observation. The result for concentration is expressed in terms of one-dimensional integrals along the concentration signal line. The solution of the transport problem in the presence of advection is obtained by transition into the coordinate system accompanying advection. The key elements entering the resulting concentration expression are the effective time and impurity displacement, both are caused by advection.     

Investigation of an ion-implanted semiconductor layer by X-ray fluorescence analysis and ellipsometry

A method for determining the depth distribution of ion-implanted impurity atoms in semiconductors is developed. The method consists in measuring the concentration of impurities by X-ray fluorescence analysis upon the ellipsometry controlled removal of thin semiconductor layers. It is found that the prolonged low-energy X-ray radiation exposure of an ion-implanted semiconductor layer leads to a change in the distribution profile of the ion-implanted impurity atoms.     

Self-consistent analysis of double-δ-doped InAlAs/InGaAs/InP HEMTs

We have carried out a theoretical study of double-5-doped InAlAs/InGaAs/InP high electron mobility transistor （HEMT） by means of the finite differential method. The electronic states in the quantum well of the HEMT are calculated self-consistently. Instead of boundary conditions, initial conditions are used to solve the Poisson equation. The concentration of two-dimensional electron gas （2DEG） and its distribution in the HEMT have been obtained. By changing the doping density of upper and lower impurity layers we find that the 2DEG concentration confined in the channel is greatly affected by these two doping layers. But the electrons depleted by the Schottky contact are hardly affected by the lower impurity layer. It is only related to the doping density of upper impurity layer. This means that we can deal with the doping concentrations of the two impurity layers and optimize them separately. Considering the sheet concentration and the mobility of the electrons in the channel, the optimized doping densities are found to be 5 × 10^12 and 3× 10^12 cm^-2 for the upper and lower impurity layers, respectively, in the double-5-doped InAlAs/InGaAs/InP HEMTs.     

Density of states of a disordered Hubbard model using the modified moments method

We apply the modified-moments method to compute the density of states of the impurity band of a doped semi-conductor in the intermediate region of impurity concentrations. This method is used to correct the density of states obtained by interpolating between the high and low concentration limit asymptotic expressions. The calculation is based on the Hubbard model in the atomic limit without spin ordering. The overlap integral is assumed to be a Gaussian function of the impurity separation. Use is made of the first seven moments of the exact distribution and of the low and high concentration limit approximations previously calculated. The first six moments are employed to determine the orthogonal polynomial expansion of the density of states while the seventh moment is used as a check on the accuracy of the distribution obtained. The results are similar to the previous ones using a truncated Edgeworth series for the correction term but the present method has the advantage of being a more systematic approach.