气体放电阴极鞘层氩离子的自洽蒙特卡罗模拟

建立了气体放电阴极鞘层离子的自洽蒙特卡罗模拟模型,考虑了离子与中性原子的电荷交换碰撞和弹性散射,用到了精确依赖于离子能量的电荷交换和动量输运截面。模拟了氩离子在阴极鞘层中的运动,得到了不同气压下自治电场分布,离子的能量分布和角分布,发现:离子由鞘层边界向阴极运动过程中,离子能量分布的高能部分逐渐增大,角分布向小角度部分压缩,鞘层中的强电场加速和聚焦了离子;在鞘层边界附近的电场呈非线性。     

气体放电空心阴极鞘层氩离子的蒙特-卡罗模拟研究

建立了气体放电空心圆筒阴极鞘层离子的自洽蒙特-卡罗模拟模型,对鞘层区内离子的输运过程进行了研究。考虑了离子与中性原子的电荷交换碰撞和弹性散射,用到了精确依赖于离子能量的电荷交换和动量输运截面。模拟了氩离子在空心阴极鞘层中的运动,得到了不同放电条件下自洽电场分布,离子的能量分布,角分布以及电子密度分布和离子密度分布。计算结果表明:离子在由鞘层边界向阴极运动过程中,离子能量分布的高能部分逐渐增大,角分布向小角度部分压缩,鞘层中的强电场对离子起加速和聚焦作用;在鞘层内离子密度分布比较均匀,只是在鞘层边界附近变化 关键词：     

高氯酸根及其离子对光谱指认的量子化学研究

利用红外和拉曼光谱研究了不同浓度下高氯酸锂在N,N-二甲基甲酰胺、乙腈、四氢呋喃、丙酮、二甲亚砜、乙酸甲酯等有机溶剂中的缔合情况,分析了高氯酸根v1谱带的变化,指认了溶液中光谱自由离子、直接接触离子对和离子对二聚体.使用量子化学方法计算了不同结构直接接触离子对和离子对二聚体的稳定构型和光谱行为,并和实验值进行了比较,考察了溶剂化模型、溶剂分子对直接接触离子对或离子对二聚体结构的影响,探讨了量子化学方法指认离子对的可能性和正确性.     

离子引出收集的沉积与溅射研究

研究离子引发收集过程中的沉积和溅射特性,给出了离子沉积和溅射的数理模型,其中重点分析了结合能、捕获概率和溅射系数这几个参数的物理意义和计算公式,给出了收集板总收集量和损失量.并且用计算机模拟了收集板的收集,给出不同的离子入射能量下入射离子元素沉积厚度和不同元素靶对各入射离子溅射特性的影响.得出以下的结论:随着离子沉积在收集板表面涂层厚度的增加溅射率也增加;离子的引出电压不是越高越好;轻质量离子的总收集率比较小;入射离子沉积和溅射特性和收集板靶原子质量有关,质量轻的金属材料作收集板,有利于提高离子的收集率. 关键词： 溅射 捕获概率 溅射概率     

Dy~(3+)-Tb~(3+)掺杂氟氧碲酸盐玻璃的光谱性能研究

实验采用高温熔融法制备了一系列Dy3+离子、Tb3+离子单掺或共掺氟氧碲酸盐玻璃样品.测试了不同摩尔含量的Dy3+离子和Tb3+离子的氟氧碲酸盐玻璃样品的密度,分析了紫外-可见透射光谱、激发光谱、发射光谱、发光衰减曲线,研究了不同摩尔含量的Dy3+离子和Tb3+离子的氟氧碲酸盐玻璃样品光谱性能及Dy3+离子到Tb3+离子能量传递机理.结果表明:Dy3+离子、Tb3+离子单掺或共掺氟氧碲酸盐玻璃样品的密度均大于5g·cm-3,最大可达6.09g·cm-3;Dy3+离子可以敏化Tb3+离子,促进其发光,但当Dy3+离子超过一定浓度后,会发生离子间浓度猝灭效应,Tb3+离子的发光反而降低.试验测得,Dy3+离子的最佳掺杂浓度为1.0mol%,此时,Tb3+离子掺杂浓度为6.0mol%,Tb3+离子发光效果最强.依据Dexter能量传输理论,并对Dy3+离子和Tb3+离子的能级图及能级间的跃迁进行分析,可知Dy3+离子和Tb3+离子间的能量传递方式为非辐射共振传递.     

氟化物、氟磷酸盐和磷酸盐玻璃中Er~(3+)离子的发光研究

测定了氟化物、氟磷酸盐和磷酸盐玻璃中Er~(3+)离子的吸收、荧光和激发光谱,解释了基质玻璃对Er~(3+)离子发光的影响。进一步研究了在这三种基质玻璃中Er~(3+)离子发光的浓度效应和温度效应,讨论了Er~(3+)离子内和离子间的能量转移过程。     

等效回路法在离子液体电极效应中的应用

利用等效电回路模型简化离子液体的电极系统,分析了电极效应中出现的3个特征频率和各自表征的物理意义.基于离子液体介电谱实验数据,获取了等效电回路的基本参数:本体电容、本体电阻和电双层电容,进而得到离子液体样品和电双层的基本介电参数,以及与离子迁移相关的物性参数如扩散系数、迁移率、离子液体中有效离子浓度,对深入理解离子液体导电和界面机制有重要的意义.     

EAST H模等离子体中离子内部输运垒特性的初步实验研究

为了研究EAST上H模等离子体中离子内部输运垒(ITB)的特性,利用电荷交换复合光谱诊断,分析了离子ITB形成和稳态阶段等离子体离子温度和环向旋转速度的时空演化。结果表明,在离子ITB形成和稳定期间,ITB肩部附近(R=1.928m)的离子温度梯度增加时,ITB区域(R=1.984m)的离子温度梯度会有所降低,反之亦然。考虑到在离子ITB形成前,芯部区域不同半径位置的离子温度梯度同时增加或减小,得到了在R=1.984m处判断离子ITB是否形成的归一化离子温度梯度的阈值。     

非对称离子门控制方法和对离子迁移谱分辨率的改善

为了改进离子门的驱动方式,简化离子门驱动电源设计和提高离子迁移谱分辨率,通过增加一组电阻实现离子门两端的不对称供电,再对低电压端的电压进行控制实现离子门功能。分析了该方式下的两种情况对迁移管内的电场、离子迁移谱的分辨率和信噪比的影响。借助SIMION7.0对离子门两边的电场分布进行了模拟和比较,并应用数值化拉普拉斯方程的方法计算了迁移管轴线的电场数据。实验证明：相比常规迁移谱的离子门浮地驱动电源,这种驱动方法成本低,离子门电源的设计简单,能够明显提高离子迁移谱的分辨率。该方法能够应用于离子迁移谱的测量仪器或实验设备。     

甲基异戊酮的离子迁移谱

在自行研制的离子迁移谱仪器上,制备了反应离子质子化水团蔟离子[H＋（H2O）n],并研究了甲基异戊酮的迁移谱。甲基异戊酮的产物离子峰的个数由浓度决定,当浓度在0.004μg/L时出现一个产物离子峰,当浓度达到0.1μg/L时出现两个产物离子峰,当浓度达到1μg/L时出现一个产物离子峰。甲基异戊酮与反应离子发生反应,生成单体团簇离子和二聚体团簇离子。实验测量了各种离子的约化迁移率。     

Characteristics of the fast electron emission produced during the cleavage of crystals

The present paper reports the fast electron emission produced during the cleavage of alkali halide crystals and models the dynamics of the process. The mechano-emission arises as a result of the ionization of surface traps at the expense of the energy which is released in the annihilation of the defects which are formed during cleavage. The slow electrons which appear upon the ionization of surface traps are subsequently accelerated in the field of negatively charged segment of the freshly cleaved surface. Considering the basic mechanism of fast electron emission, expressions are derived which are able to explain satisfactorily the temporal, thermal, charge, surface, coloration, water adsorption and other characteristics of the fast electron emission produced during the cleavage of crystals. The decay time of the charges on the newly created surfaces, and the velocity of cracks can be determined from the measurements of fast electron emission produced during the cleavage of crystals. It is shown that two types of diffusing centres are responsible for the charge relaxation and thereby for the emission of fast electrons produced during the cleavage of alkali halide crystals.     

Fast reconnection in nonrelativistic 2D electron-positron plasmas

In this Letter, we put forth (and validate numerically) a fluid-based analytical theory, which predicts that fast reconnection in nonrelativistic, low-beta pair plasmas is possible in collisionless regimes. This novel theoretical result complements recent kinetic computational evidence and challenges the accepted understanding, which considers fast dispersive waves (not supported in pair plasmas) as the key enabling physics ingredient for fast reconnection. The implications of this theory for the understanding of fast reconnection in standard electron-proton plasmas are discussed.     

Quartz fast component opticallystimulated luminescence: Towards routine extraction for dating applications

Using an uncontaminated fast component is a key for improving the reliability of quartz OSL dating for many deposits. So far no approach to extract the fast component of quartz OSL has routinely been adopted for dating practice. Key challenges for extracting fast components are (1) the difficulty of finding a unique solution in curve-fitting deconvolution of OSL decay curves and (2) the relatively poor dating precision when using experimental fast component extraction. Here, a simple mathematic solution for fast component extraction is presented that is not relying on curve-fitting deconvolution and can easily be adopted into routine dating practices. By using specifically selected data points from smoothed OSL decay curves, the precision of equivalent doses calculated using the extracted fast component can be improved over equivalent doses calculated using bulk OSL. The fast component extraction is tested on a group of age-constrained samples containing both insufficiently bleached and sufficiently bleached deposits. Fast component OSL ages are as accurate as bulk OSL ages for the sufficiently bleached deposits, but more accurate for samples where bulk OSL is affected by insufficient bleaching. We also demonstrate how using a curve smoothing procedure can improve dating precision in case of both sufficiently and insufficiently bleached deposits.     

快Z箍缩物理过程的PSPICE电路模拟方法分析

 简单介绍了快Z箍缩概念和物理过程，以及Z箍缩物理过程不稳定性因素和简单分析。用PSPICE电路模拟方法解薄壳模型得到了箍缩时间、等离子体壳的速度、负载上的电流、电压变化规律等Z箍缩物理量。     

The influence of fast neutron irradiation on the IR optical properties of NTD-Silicon

Optical IR measurements of NTD-Si are presented for different fast neutron doses. The exponential dependence of the divacancy concentration and the near-edge absorption as a function of fast neutron flux is reported. Silicon one-phonon absorption, caused by the irradiation, is also increasing with the rising percentage of fast neutrons in the flux     

Fast filtering algorithm based on vibration systems and neural information exchange and its application to micro motion robot

This paper develops a fast filtering algorithm based on vibration systems theory and neural information exchange approach. The characters, including the derivation process and parameter analysis, are discussed and the feasibility and the effectiveness are testified by the filtering performance compared with various filtering methods, such as the fast wavelet transform algorithm, the particle filtering method and our previously developed single degree of freedom vibration system filtering algorithm, according to simulation and practical approaches. Meanwhile, the comparisons indicate that a significant advantage of the proposed fast filtering algorithm is its extremely fast filtering speed with good filtering performance. Further, the developed fast filtering algorithm is applied to the navigation and positioning system of the micro motion robot, which is a high real-time requirement for the signals preprocessing. Then, the preprocessing data is used to estimate the heading angle error and the attitude angle error of the micro motion robot. The estimation experiments illustrate the high practicality of the proposed fast filtering algorithm.     

A fast spin echo two-point Dixon technique and its combination with sensitivity encoding for efficient T2-weighted imaging

A fast spin echo two-point Dixon (fast 2PD) technique was developed for efficient T2-weighted imaging with uniform water and fat separation. The technique acquires two interleaved fast spin echo images with water and fat in-phase and 180° out-of-phase, respectively, and generates automatically separate water and fat images for each slice. The image reconstruction algorithm uses an improved and robust region-growing scheme for phase correction and achieves consistency in water and fat identification between different slices by exploiting the intrinsic correlation between the complex images from two neighboring slices. To further lower the acquisition time to that of a regular fast spin echo acquisition with a single signal average, we combined the fast 2PD technique with sensitivity encoding (SENSE). Phantom experiments show that the fast 2PD and SENSE are complementary in scan efficiency and signal-to-noise ratio (SNR). In vivo data from scanning of clinical patients demonstrate that T2-weighted imaging with uniform and consistent fat separation, including breath-hold abdominal examinations, can be readily performed with the fast 2PD technique or its combination with SENSE.     

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为了研究靶材料对快电子能量分布的影响,采用电子谱仪测量了飞秒激光与Cu和CH靶相互作用中在靶前和靶后产生的快电子能谱。结果显示,在靶前Cu和CH靶的快电子能谱相似,反应了快电子发射对靶材料的依赖性较弱;在靶后Cu和CH靶的快电子能谱具有明显的差异,说明电子的输运过程与靶材料密切相关。冷电子环流以及自生磁场是导致Cu靶快电子能谱"软化"的原因,而对于CH靶麦克斯韦分布的快电子能谱主要由碰撞机制决定。     

Simultaneous measurement of retardation and fast axis angle of eighth-wave plate in real time

A simultaneous measurement method for the retardation and the fast axis angle of the eighth-wave plate in real time is proposed. The beam emitted from the laser passes through the circular polarizer and the eighth-wave plate to be measured successively, and then is split by the Dammann grating to form three sub-beams. They are analyzed by an analyzer array and detected by a detector array. Three detection signals are obtained simultaneously to calculate the retardation and the fast axis angle in real time. In experiments, a crystal quartz sample is measured at different fast axis angles. The average and standard deviation of its retardation respectively are 40.9°and 0.5°. The maximum measurement deviation of the fast axis angle is 2.1°. The usefulness of the method is verified.     

聚变等离子体中的快离子压强

本文运用Fokker-Planck方程的慢化近似,考虑存在多种离子成份(包括杂质),假定它们具有共同的温度,我们得到了聚变产生的快离子压强的简单封闭形式表示式。表明在典型的工作温度下(～60keV),D-~3He等离子体中聚变产生的快离子压强约为本底热压强的20％,这与D-T等离子体工作在20keV时的比值几乎相同。因此,D-~3He和D-T在它们相应的预期工作温度下,它们各自的快离子压强对总压强的影响是类似的,然而在更高的温度下,这个比值将变得更大。