HT-7装置液态锂限制器实验中锂的腐蚀与沉积特性的研究

在磁约束聚变等离子体装置中, 面对等离子体的第一壁将直接影响高温等离子体性能及第一壁寿命, 具有表面自我修复的、能有效抑制边界粒子再循环的液态金属锂第一壁越来越被重视, 其中液态锂第一壁与等离子体相互作用的研究尤其重要. 本文研究了HT-7装置液态锂限制器实验中锂的表面腐蚀及在装置内沉积特性、及其对等离子体性能影响. 实验表明, 当锂与等离子体相互作用较弱时, 锂以微弱的蒸发及溅射形式从表面腐蚀并进入等离子体, 表现为锂的线辐射有所增强, 等离子体内杂质水平降低, 氢再循环降低, 有利于等离子体约束性能提高; 当锂与等离子体间的相互作用比较强时, 锂主要以锂滴形式直接进入等离子体, 引起锂的辐射爆发, 最终引发等离子体放电破裂. 通过对锂斑及样品的分析发现, 锂主要沉积在限制器周围, 并且在低场侧及沿着等离子体电流方向沉积居多, 表现为极向和环向分布不均匀, 这也导致边界粒子再循环分布的不均匀. 这些实验为研究液态锂第一壁与等离子体相互作用, 分析液态锂第一壁在托卡马克装置上应用具有重要参考意义.     

Structural and electrochemical study on Li(Li1/3Ti5/3)O4 anode material for lithium ion batteries

Chemical and electrochemical studies have shown that various titanium oxides can incorporate lithium in different ratios. Other compounds with a spinel-type structure and corresponding to the spinel oxides LiTi₂O₄ and Li₄Ti₅O₁₂ have been evaluated in rechargeable lithium cells with promising features. The spinel Li[Li_1/3Ti_5/3]O₄ [1–5] compound is a very appealing electrode material for lithium ion batteries. The lithium insertion-deinsertion process occurs with a minimal variation of the cubic unit cell and this assures high stability which may reflect into long cyclability. In addition, the diffusion coefficient of lithium is of the order of 10⁻⁸ cm²s⁻¹ [5] and this suggests fast kinetics which may reflect in high power capabilities. In this work we report a study on the kinetics and the structural properties of the Li[Li_1/3Ti_5/3]O₄ intercalation electrode carried out by: cyclic voltammetry, galvanostatic cycling and in-situ X-ray diffraction. The electrochemical characterization shows that the Li[Li_1/3Ti_5/3]O₄ electrode cycles around 1.56 V vs. Li with a capacity of the order of 130 mAhg⁻¹ which approaches the maximum value of 175 mAhg⁻¹ corresponding to the insertion of 1 equivalent per formula unit. The delivered capacity remains constant for hundred cycles confirming the stability of the host structure upon the repeated Li insertion-deinsertion process. This high structural stability has been confirmed by in situ Energy Dispersion X-ray analysis. Paper presented at the 7th Euroconference on Ionics, Calcatoggio, Corsica, France, Oct. 1–7, 2000.     

Li NMR in lithium borate glasses

In anticipation of using fluctuations in the nuclear dipolar and quadrupolar interaction as a probe of lithium ion motion in lithium borate glasses, the static values of these interactions were measured using a variety of echo techniques. The static quadrupolar echo spectrum of ⁷Li and a calculation of the dipolar interaction in crystalline Li₂B₄O₇ (same chemical composition as the glass under study) were used to estimate the strength of the two interactions. These indicate that the dipolar and quadrupolar interactions for ⁶Li will be of similar size and the dipolar interaction will be dominated by the unlike spin interaction between the ⁶Li and the ¹⁰B, ¹¹B spins. An appropriate theoretical model is proposed and explicit expressions for the echo amplitude are calculated in terms of the dipolar and quadrupolar second moments. This single spin model takes into account the quadrupolar interaction but treats the dipolar interaction as an effective magnetic field. Experimental results are presented which show the essential validity of the model and measurements lead to reasonable values for the dipolar and quadrupolar second moments. The relative merits of the various echo techniques are discussed.     

6Li NMR in lithium borate glasses

In anticipation of using fluctuations in the nuclear dipolar and quadrupolar interaction as a probe of lithium ion motion in lithium borate glasses, the static values of these interactions were measured using a variety of echo techniques. The static quadrupolar echo spectrum of ⁷Li and a calculation of the dipolar interaction in crystalline Li₂B₄O₇ (same chemical composition as the glass under study) were used to estimate the strength of the two interactions. These indicate that the dipolar and quadrupolar interactions for ⁶Li will be of similar size and the dipolar interaction will be dominated by the unlike spin interaction between the ⁶Li and the ¹⁰B, ¹¹B spins. An appropriate theoretical model is proposed and explicit expressions for the echo amplitude are calculated in terms of the dipolar and quadrupolar second moments. This single spin model takes into account the quadrupolar interaction but treats the dipolar interaction as an effective magnetic field. Experimental results are presented which show the essential validity of the model and measurements lead to reasonable values for the dipolar and quadrupolar second moments. The relative merits of the various echo techniques are discussed.     

Studying Li and He− in the 1s2s2p configuration

Expressions are derived for the nonrelativistic energy of the 1s2s2p configuration. In both the possible electron momentum binding systems (1s2s)2p and 1s(2s2p) values are determined for the parameters of the generalized hydrogenlike analytical radial orbitals for a lithium atom and a negative helium ion. The Li and He^– energy spectra in the 1s2s2p configuration are compared with the theoretical calculations of other authors and with experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 70–74, June, 1977.     

A general solution procedure for vibrations of systems with cubic nonlinearities and nonlinear/time-dependent internal boundary conditions

The subject of this paper is the development of a general solution procedure for the vibrations (primary resonance and nonlinear natural frequency) of systems with cubic nonlinearities, subjected to nonlinear and time-dependent internal boundary conditions—this is a commonly occurring situation in the vibration analysis of continuous systems with intermediate elements. The equations of motion form a set of nonlinear partial differential equations with nonlinear, time-dependent, and coupled internal boundary conditions. The method of multiple timescales, an approximate analytical method, is applied directly to each partial differential equation of motion as well as coupled boundary conditions (i.e. on each sub-domain and the corresponding internal boundary conditions for a continuous system with intermediate elements) which ultimately leads to approximate analytical expressions for the frequency-response relation and nonlinear natural frequencies of the system. These closed-form solutions provide direct insight into the relationship between the system parameters and vibration characteristics of the system. Moreover, the suggested solution procedure is applied to a sample problem which is discussed in detail.     

Direct numerical simulation of quasi-three-level passive Q-switched laser

The Runge-Kutta method is used to solve numerically the rate equations of quasi-three-level passive Q-switched laser directly without any approximate treatment of these differential equations. The 946 nm self-Q-switched Cr,Nd:YAG laser is chosen for example to describe the details. The time-dependence of intra-cavity photon density is obtained and its detailed real-time changing process is reproduced in numerical solution. The curves of laser output parameters such as average output power, pulse width, repetition rate, pulse energy and peak power changing with different cavity conditions such as pump power, output coupler reflectivity, Cr,Nd:YAG crystal length, Nd³⁺ ion and Cr⁴⁺ ion concentrations are simulated according to direct numerical solution rather than analytical expressions. This direct numerical simulation method can be widely used to describe and optimize the quasi-three-level passive Q-switched laser theoretically.     

方形自聚焦透镜折射率分析

利用MATLAB 偏微分方程工具箱(PDE)实现方形玻璃纤维边界条件下离子扩散的有限元解法,给出一般步骤,对离子交换制备方形自聚焦透镜过程进行计算机模拟.运用分离变量法求解方形玻璃纤维中Tl+离子浓度定解方程,由离子浓度与折射率的线性关系,得到了方形自聚焦透镜折射率分布的数学表达式,计算出折射率分布图以及理论值.与实验值校验表明,相对误差小于0.33%.     

Femtosecond laser-induced-breakdown spectrometry for Ca<Superscript>2+</Superscript> analysis of biological samples with high spatial resolution

We describe an analytical method for element-specific in situ investigations of biological samples with high spatial resolution, using laser-induced-breakdown spectroscopy (LIBS). The prerequisites for spatially highly resolved LIBS are an appropriate analytical performance in combination with precise micro-ablation conditions, both laterally and axially. In order to identify the best suitable laser source, the analytical performance and the ablation process were studied for ns-LIBS and fs-LIBS. The analytical performance was studied on an aqueous solution of CaCl₂, where water served as a first substitute for biological material. The ablation process was investigated in the outer epidermal wall of a sunflower seedling stem. Besides direct measurements, the physiology of the sunflower seedling can be used in order to estimate the ablation depth. Our results show that analytical measurements with high spatial resolution can be performed on biological samples using fs-LIBS. This was demonstrated by in situ measurements of wall-associated calcium ion (Ca²⁺) distributions within the peripheral cell wall of the sunflower seedling (Helianthus annuus L.) stem. In this biological sample an axial resolution of about 100 nm was achieved. PACS 52.50.Jm; 42.62.Be; 78.47.+p; 87.16.-b     

LiNi1/3Co1/3Mn1/3O2 cathode materials for LIB prepared by spray pyrolysis. II. Li+ diffusion kinetics

Layered lithium ion battery cathode material LiNi_1/3Co_1/3Mn_1/3O₂ with a uniform particle size of about 6 μm was synthesized by a spray pyrolysis method. The lithium ion diffusion kinetics in LiNi_1/3Co_1/3Mn_1/3O₂ composite cathode were systematically studied by the ratio of potentio-charge capacity to galvano-charge capacity method, galvanostatic intermittent titration technique, electrochemical impedance spectroscopy, and potential step chronoamperometry methods. The variations of lithium ion diffusion coefficients obtained by the four methods show a close similarity. They vary in the range of 10^?8 to 10^?10 cm² s^?1, with a maximum at 4.1- to 4.2-V voltage level.     

Relativistisch invariante Beschreibung strukturierter Elementarteilchen

Within a dynamic theory of fusion the three-particle-system is examined. Under suitable boundary conditions a method of integra ion is developed, which yields the exact solution of the relativistic three-particle-equation. This solution describes an elementary particle with internal structure. A thorough discussion of the collective motion supplies the massM and spin 1/2 for the new particle and the proper Diracequation, so that an identification of the three-particle-system with the electron is possible.     

Elastic scattering of an electron by the negative lithium ion

In the framework of the many-body theory, the differential and total cross sections of elastic scattering of slow electrons by the negative lithium ion Li⁻ are obtained. Calculations are performed both in the Hartree-Fock single-particle approximation and with regard to many-electron correlations, which take into account the dynamic polarization of the core. Features observed in the behavior of the phases and cross sections for p and d partial waves are associated with resonance scattering of electron waves. Considering the dynamic polarization of the core by an incident electron heightens the diffraction character of the scattering. The real process is compared with particle scattering in models with a repulsive potential.     

Charge accumulation by insulators irradiated with electrons

A model, more general than the existing ones, is proposed for the accumulation of charge by plane-parallel insulators irradiated with accelerated electrons. The model takes into account the spatial distribution of the charge injected by the irradiation and the coordinate and time dependence of the bulk electrical conductivity; it is valid for different boundary conditions imposed on the solution of the Poisson equation. The charge density distribution obtained by the light probe method in a sample of a lithium fluoride single crystal irradiated with 2-MeV electrons and current density 5·10^–4 A/m² is described qualitatively by the model.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 49–57, February, 1981.     

6,7Li NMR study of ion mobility on the molecular scale in lithated imidazole complexes

Two model compounds, lithium imidazolium (LiIm) and lithium 2-undecylimidazolium (und-LiIm), were synthesized. These materials are chosen as models of potential lithium ion conductors for use as electrolytes in lithium batteries. Solid-state NMR was used to provide information on the microscopic interactions including ionic mobility and ring reorientations which govern the efficiency of conductivity. Lithium imidazolium was mixed with lithium methylsulfonate, generating a doped complex in which a doubly lithiated imidazole ring was inferred based on the ⁷Li NMR chemical shifts. Our research includes ^6,7Li variable temperature MAS NMR experiments at intermediate spinning speeds, relaxation studies to determine spin-lattice relaxation times (T₁) of lithium ion hopping, and 2D exchange spectroscopy to determine possible chemical exchange processes. The possibility of 2-site ring reorientation for the doubly lithiated imidazole ring was supported by exchange spectroscopy. Comparisons of spin-lattice relaxation times and corresponding activation energies of the lithium imidazolium and the doped complex point to a higher degree of mobility in the latter.Lithium 2-undecylimidazolium was prepared and exhibited a lower melting point than the parent lithium imidazolium, as expected. This small molecule was chosen as representative of a side-chain functionalized polyethylene-based material. ⁷Li MAS spectra show mainly the presence of the doubly lithiated imidazole ring in pure und-LiIm, and in the LiCH₃SO₃–und-LiIm mixture. The data clearly indicate local mobility of the lithium ions in the materials.     

Electron-stimulated desorption of lithium ions from lithium halide thin films

Electron-stimulated desorption of positive lithium ions from thin layers of lithium halides deposited onto Si(1 1 1) are investigated by the time-of-flight technique. The determined values of isotope effect of the lithium (⁶Li⁺/⁷Li⁺) are 1.60 ± 0.04, 1.466 ± 0.007, 1.282 ± 0.004, 1.36 ± 0.01 and 1.33 ± 0.01 for LiH, LiF, LiCl, LiBr and LiI, respectively. The observed most probable kinetic energies of ⁷Li⁺ are 1.0, 1.9, 1.1, 0.9 and 0.9 eV for LiH, LiF, LiCl, LiBr and LiI, respectively, and seem to be independent of the halide component mass. The values of lithium ion emission yield, lithium kinetic energy and lithium isotope effect suggest that the lattice relaxation is only important in the lithium ion desorption process from the LiH system. In view of possible mechanisms and processes involved into lithium ion desorption the obtained results indicate that for LiH, LiCl, LiBr and LiI the ions desorb in a rather classical way. However, for LiF, ion desorption has a more quantum character and the modified wave packet squeezing model has to be taken into account.     

大气压液体阴极辉光放电-原子发射光谱法应用于血清中微量锂元素的测定

含锂药剂在用于临床治疗精神疾病时需要对患者血清中锂元素浓度进行监测以在控制正常药效的同时防止锂中毒事故的发生。目前临床医学检验血清中锂元素含量主要采用火焰原子吸收光谱和基于离子选择性电极的电化学技术。但火焰原子吸收光谱技术需要使用乙炔钢瓶和空气压缩机,存在仪器不能便携,对实验室条件要求苛刻等缺点;电化学方法存在电极处理与更换繁琐,分析效率相对偏低等问题。同时,仪器可便携、操作简单且对锂元素分析具有良好分析性能的液体阴极辉光放电-原子发射光谱技术尚未应用于医疗领域血清中锂含量的测定。因此,基于自制便携液体阴极辉光放电-原子发射光谱装置,建立了血清中锂元素的高灵敏度分析方法。系统考察了10～100倍血清样品稀释倍数对血清样品测试的干扰,结果表明,当血清样品稀释20倍以上时,未发现显著的基体干扰,可以较好地保证结果的可靠性。对影响锂元素分析性能的分析谱线、试液酸度等参数进行了系统优化, 结果表明671 nm为锂元素最佳测试谱线;试液酸度对锂元素分析的灵敏度和稳定性影响显著,采用1%硝酸（V/V）试液酸度可以保证良好的分析性能。在优化的系统参数和实验条件下,锂元素标准曲线的回归方程为：Ie=7 299ρ_Li+400;R2=0.998 3。当血清样品稀释20倍时,该方法对锂元素的检出限为0.2 mg·L-1。对同一血清样品6次重复测试考察本方法的重复性,相对标准偏差小于5%。将本方法应用于血清标准样品（Trace Elements Serium L-2）中锂含量分析,测定值与证书标称值一致。表明该方法可以较好地应用于医疗检验领域实际血清样品中微量锂元素含量的测定。     

Lithium insertion into nanometer-sized rutile-type TixSn1 − xO2 solid solutions

The electrochemical properties of rutile-type Ti_xSn_1?xO₂ solid solutions (x = 0–1.0) as an anode for a lithium–ion battery were investigated using nanosized crystals prepared by an aqueous solution process. The reduction of the crystal size to nanoscale allowed a smooth lithium insertion into the rutile framework at room temperature. The lithium-insertion behavior of TiO₂, SnO₂, and the solid solutions was evaluated without any structural change of the rutile-type crystal structure in the potential range of 1.2–3.5 V (versus Li/Li⁺). The interstitial spaces for lithium ions were found to be derived from the crystal structure of the rutile framework and independent of the metal species.     

Numerical analysis of the one-dimensional heat equation subject to a boundary integral specification

In this research a numerical technique is developed for the one-dimensional heat equation that combines classical and integral boundary conditions. New matrix formulation techniques with arbitrary polynomial bases are proposed for the numerical/analytical solution of this kind of partial differential equation. We give a simple and efficient algorithm based on an iterative process for numerical solution of the method.     

An elastodynamic solution of finite long orthotropic hollow cylinder under torsion impact

The paper presents an analytical method to solve the elastodynamic problem of a finite-length orthotropic hollow cylinder subjected to a torsion impact often occurring in engineering fields. The elastodynamic solution is composed of a quasi-static solution of homogeneous equation satisfied with the non-homogeneous boundary condition and a dynamic solution of non-homogeneous equation satisfied with homogeneous boundary condition. The quasi-static solution can be obtained by directly solving the quasi-static equation satisfied with the non-homogeneous boundary condition. The solution of a non-homogeneous dynamic equation is obtained by means of a finite Hankel transform to a radial variable r, Laplace transform to a time variable t and finite Fourier transform to an axial variable z. Thus, the elastodynamic solution of the finite length of an orthotropic hollow cylinder subjected to a torsion impact is obtained. On the other hand, a dynamic finite element for the same problem is also carried out by applying the ANSYS finite-element analysis system. Comparing the theoretical solution with finite-element solution, it can be found that two kinds of results obtained by making use of two different solving methods are suitably approached. Therefore, it is further concluded that the methods and computing processes of the theoretical solution are effective and accurate.     

The R-function method for the free vibration analysis of thin orthotropic plates of arbitrary shape

Free flexural vibrations of homogeneous, thin, orthotropic plates of an arbitrary shape with mixed boundary conditions are studied using the R-function method. The proposed method is based on the use of the R-function theory and variational methods. In contrast to the widely used methods of the network type (finite differences, finite element, and boundary element methods), in the R-function method all the geometric information given in the boundary value problem statement is represented in an analytical form. This allows one to seek a solution in a form of some formulas called a solution structure. These solution structures contain some indefinite functional components that can be determined by using any variational method. A method of constructing the solution structures satisfying the required mixed boundary conditions for eigenvalue plate bending problems is described. Numerical examples for the vibration analysis of orthotropic plates of complex geometry with mixed boundary conditions for illustrating the aforementioned R-function method and comparison against the other methods are made to demonstrate its merits.