激光直接加热自背光法辐射不透明度测量方法探索

本文提出一种基于单束激光直接加热多层平面靶开展 稠密等离子体辐射不透明度特性研究的靶物理设计并对其进行了实验验证. 在XG-II激光装置上, 采用三倍频束匀滑激光辐照Au/CH/Al/CH多层平面靶产生背光源和Al样品等离子体, 通过观测背光源经样品等离子体衰减后的透过谱得到样品等离子体的辐射吸收性质. 采用Multi-1D程序对激光加热多层靶进行了辐射流体力学数值模拟, 给出了样品等离子体状态及其时间演化过程. 利用细致谱项模型 (DTA) 对实验测量的Al等离子体吸收谱进行理论分析, 表明等离子体温度在20–70 eV之间, 该结果与辐射流体力学模拟结果基本一致. 关键词： 吸收光谱 自背光 激光等离子体     

咔唑分子拉曼激发虚态的相关研究

根据键极化率与拉曼峰强之间的关系,得到咔唑分子拉曼激发虚态随时间演化的键极化率. 将得到的键极化率的末态与用密度泛函理论得到的基态键电荷密度进行了对比,讨论并分析了拉曼激发虚态键极化率随时间弛豫的特征. 研究表明:咔唑分子在拉曼激发初态时,电子由两个骨架六元环向连通两六元环的连通键上流动,而并非向外围的C–H键上流动. 拉曼激发末态键极化率分布趋势与基态键电荷密度分布很相似,说明激发的电子又流回到分子骨架,即弛豫到基态. 通过对拉曼激发虚态键极化率弛豫过程特征时间的研究,发现连通两六元环的C–C键以及靠近连通键的C–C键的键极化率的弛豫时间较其他键的极化率弛豫时间都长,进一步说明了拉曼激发虚态电子弛豫特征. 这些结果反映了咔唑这类具有连通键的多元环分子在拉曼激发虚态所具有的特征与性质,这对拉曼激发虚态的研究有重要意义. 关键词： 拉曼峰强 键极化率 拉曼激发虚态     

激光导致等离子体空泡及高速离子产生的粒子模拟研究

 用二维半粒子模拟程序PLASIM模拟研究了超强的S极化激光束与过稠密等离子体的相互作用过程，发现等离子体在其表面形成了波纹状结构（等离子体空泡），该现象也称为类瑞利-泰勒不稳定性；发现离子得到很大加速，其相对论动能可以达到72 MeV，并研究了高速离子的分布特点及其产生原因。     

Debye屏蔽势下的Na原子

结合自由Na原子的l-依赖模型势, 采用B-样条基组展开方法计算了等离子体环境中Na原子的的基态能量、振子强度、偶极极化率、四极极化率、八极极化率等随Debye长度的变化. 其中原子的等离子体效应采用Debye屏蔽模型. 计算结果与其他研究者的结果符合得很好; 在Debye屏蔽等离子体环境下下基态能量的结果与Sahoo [Sahoo S Ho Y K 2006 Phys. Plasmas 13, 063301]和Li [Li H W and Kar S, 2012 Phys. Plasmas 19, 073303]用其他模型所得的结果基本一致; 电偶极、四极和八极极化率随Debye长度的变化趋势一致, 数值结果和Li和Kar [Li H W and Kar S, 2012 Phys. Plasmas 19, 073303] 的数量级一致.     

Debye屏蔽势下的Na原子

结合自由Na原子的l-依赖模型势, 采用B-样条基组展开方法计算了等离子体环境中Na原子的的基态能量、振子强度、偶极极化率、四极极化率、八极极化率等随Debye长度的变化. 其中原子的等离子体效应采用Debye屏蔽模型. 计算结果与其他研究者的结果符合得很好; 在Debye屏蔽等离子体环境下下基态能量的结果与Sahoo [Sahoo S Ho Y K 2006 Phys. Plasmas 13, 063301]和Li [Li H W and Kar S, 2012 Phys. Plasmas 19, 073303]用其他模型所得的结果基本一致; 电偶极、四极和八极极化率随Debye长度的变化趋势一致, 数值结果和Li和Kar [Li H W and Kar S, 2012 Phys. Plasmas 19, 073303] 的数量级一致.     

硅掺杂辉光放电聚合物薄膜的热稳定性研究

采用等离子体辉光放电聚合技术,在不同四甲基硅烷(TMS)流量条件下制备了硅掺杂辉光放电聚合物(Si-GDP)薄膜,采用傅里叶变换红外光谱、X射线光电子能谱和热重(TG)分析技术分析了不同TMS流量对Si-GDP薄膜结构与热稳定性的影响.结果表明:随着TMS流量在0–0.06 cm³/min范围变化,Si-GDP薄膜中Si的原子含量C_Si为0–16.62%;含Si红外吸收峰的相对强度随TMS流量的增加而明显增大;Si-GDP薄膜的TG分析显示,温度在300 ℃时,随TMS流量的增加,Si-GDP薄膜的失重减少,热稳定性增强. 关键词： 硅掺杂辉光放电聚合物薄膜 X射线光电子能谱 热稳定性     

一种基于超材料的宽带、反射型90°极化旋转体设计

根据各向异性媒质理论, 设计了一种宽带、反射型超材料极化旋转体, 能够将线极化波极化方向旋转90°, 极化转化率大于90%的工作带宽为5.5–14.5 GHz. 该极化旋转体由两层介质板、金属双开口谐振环和金属底板周期排列构成, 具有各向异性的特点, 单元两对角线方向的电场分量反射系数相同, 反射相位相差180°, 导致其极化旋转特性. 利用表面电流分布图, 分析不同极化波入射时该极化旋转体的谐振状态, 实验和仿真结果符合较好. 该极化旋转体在新型天线设计和隐身技术等方面具有广阔的应用前景.     

基于动态溶胀法制备中空聚合物微球

以表面带正电荷的m级聚苯乙烯微球为种子,经过甲苯、二乙烯基苯溶胀,聚合与包覆等过程制备了直径约5 m的中空聚合物微球。研究了溶剂类型、溶剂用量对动态溶胀法制备的中空聚合物微球粒径、分布和结构的影响,讨论了中空聚合物微球的形成机理。结果表明:添加一定量甲苯、二甲苯等挥发性溶剂是动态溶胀法形成中空聚合物微球的前提;甲苯用量越多,溶胀后形成的中空结构越明显,孔径越大;选择低溶解性的二甲苯溶剂更有利于中空结构的形成。     

硫化氢在金属-有机骨架材料中吸附与分离的计算模拟

摘 要: 采用优化的DREIDING力场参数,通过巨正则系综蒙特卡洛(GCMC)模拟方法对天然气中的两种气体CH4和H2S在Cu6(BTTC)4(H2O)6·xS (1)和[(CH3)2NH2]3[(Cu4Cl)3(BTTC)8]·yS (2)两种金属有机骨架(MOFs)材料中的吸附与分离性能进行了比较研究.结果证明了聚合物2的吸附量和分离性能相比之下高于聚合物1,且两种材料的吸附机理存在差异,聚合物1中金属Cu和有机基团对于吸附两种气体没有明显的作用,主要分布在小孔道和大孔道;然而聚合物2中H2S和CH4主要吸附在有机基团、金属Cu和-Cl基团周围.则含有-Cl基团的聚合物2展现了优越的吸附能力和稳定性.总而言之,本文获得的结果可以应用于此类研究领域,因此在环境范围中吸附去除污染物可以产生更深层次定性和定量的作用.     

极化X光谱诊断铝激光等离子体的电子密度

为了准确诊断激光等离子体的电子密度,提出了一种基于极化光谱的类氦共振线与互组合线相对强度比诊断电子密度的方法.该法考虑了激光等离子体发射的X射线存在极化的特性,用极化光谱理论对测量的类氦共振线和互组合线光谱相对强度比进行精密校正,再推导等离子体的电子密度.在2×10 J激光装置上进行了实验,使用极化PET（002）晶体谱仪测量了Al类氦离子光谱,利用光谱的极化特性推出Al等离子体的电子密度约为1.5×1020 cm－3.结果表明极化X光谱推导等离子体电子密度方法适合激光高温高密等离子体诊断.     

Relating plasma surface modification to polymer characteristics

This paper aims to provide an analysis of the correlation between various plasma effects on polymers exposed to atmospheric pressure plasma. The relationship linking the surface polarity, the chemical structure and composition and the crystalline/amorphous phase contribution in the surface modification mechanisms of plasma-exposed polymers is explored. Different polymers were chosen comprising of various structures, functionality, degree of oxidation, crystallinity, and were treated under a particular experimental configuration, and dielectric barrier discharge-type. The plasma parameters and the treatment settings are observed, in relation to relevant surface properties, as surface energy components, surface topography, structural changes and chemical composition, under conditions where the gaseous environment chosen, He-N₂, allows complex surface modification, by combined functionalisation and crosslinking. PACS 81.65.-b; 81.05.-t; 52.77.-j     

Laser plasma propulsion generation in nanosecond pulse laser interaction with polyimide film

The plasma propulsion generated in nanosecond pulse laser interaction with polyimide film is investigated. A comparison of coupling coefficient and specific impulse with glass layer and water layer confinement is given. It shows that polyimide has a higher efficiency in water confinement ablation. Through doped carbon black in polyimide film, a higher coupling coefficient is obtained. In ablated surface images, less re-deposited products on polyimide surface have been observed compared with other polymers at the same laser intensity.     

Generation of Craze-Formation Centers in Polymer Films under the Action of Electric Discharge Plasma

We propose a technology for generating craze-formation centers in polymers under the action of the electric discharge plasma and consider questions associated with a method for varying the geometrical sizes of crazes. The possibility of obtaining nanostructured polymers are also considered.     

Buckling Behavior of Carbon Nanotubes Functionalized with Carbene under Physical Adsorption of Polymer Chains: a Molecular Dynamics Study

The buckling analysis of functionalized carbon nanotubes (CNTs) is of great importance for the better understanding of mechanical behavior of nanocomposites. The buckling behavior of carbene-functionalized CNTs (cfCNTs) under physical adsorption of polymer chains (cfCNTs/polymers) is studied in this paper by the classical molecular dynamics (MD) simulations. In this regard, to investigate the interactions between non-covalent polymer chains and cfCNTs, two different non-covalent functional groups, i.e. polycarbonate (PC) and polypropylene (PP), are selected. The findings are compared with those of pure CNTs under the physical adsorption of polymer chains (pCNTs/polymers). The obtained results show that at a given weight percentage of non-covalent functional groups, the gyration radius of cfCNTs/polymers is higher than that of pCNTs/polymers. Furthermore, an increase in the critical buckling force of cfCNTs/polymers is dependent on the type of non-covalent polymer chains. For cfCNTs/PC and cfCNTs/PP, the critical buckling force is respectively lower and higher than that of pCNTs/polymers for the similar weight percentage of non-covalent functional groups. In addition, it is found that the critical buckling strain of cfCNTs/polymers is smaller than that of pCNTs/polymers for the same weight percentage of non-covalent polymer chains.     

基于平均二次电子发射系数的航天器表面起电特征分析

为了进一步贴近航天器表面起电环境以得到更加可信的分析结果,针对航天器在恶劣充电环境下的表面起电问题,考虑空间等离子体双麦克斯韦分布情况,建立了基于平均二次电子发射系数的航天器表面起电阈值方程,可在入射电子能量连续分布情况下定量分析航天器表面起电特征,其中双麦分布可更好地描述磁层亚爆期间的恶劣充电环境。经过理论分析,归纳出双麦分布下的两种典型等离子体状态。通过仿真计算,得到了在两种典型等离子体状态下航天器表面电位随等离子体浓度和温度变化的特征。结果表明:电子温度越高,表面负带电电位越高,充电越严重,与此同时,双麦分布下等离子体两种电子组分的浓度比值对带电结果有重要影响。     

Preparation of N-doped TiO<Subscript>2</Subscript> photocatalyst by atmospheric pressure plasma process for VOCs decomposition under UV and visible light sources

The nitrogen doped (N-doped) titanium dioxide (TiO₂) photocatalyst was prepared by the atmospheric-pressure plasma-enhanced nanoparticles synthesis (APPENS) process operated under normal temperature, i.e. the dielectric barrier discharge plasma process. The N₂ carrier gas is dissociated in the AC powered nonthermal plasma environment and subsequently doped into the TiO₂ photocatalyst that was capable of being induced by visible light sources. The APPENS process for producing N-doped TiO₂ showed a higher film deposition rate in the range of 60–94 nm/min while consuming less power (<100 W) as compared to other plasma processes reported in literatures. And the photocatalytic activity of the N-doped TiO₂ photocatalyst was higher than the commercial ST01 and P25 photocatalysts in terms of toluene removals in a continuous flow reactor. The XPS measurement data indicated that the active N doping states exhibited N 1s binding energies were centered at 400 and 402 eV instead of the TiN binding at 396 eV commonly observed in the literature. The light absorption in the visible light range for N-doped TiO₂ was also confirmed by a clear red shift of the UV-visible spectra.     

等离子体环境非偏置固体表面带电研究

航天器与等离子体环境中的电子、离子相互作用, 表面将出现充放电效应, 对航天器产生负面影响. 表面充电电位对充放电影响至关重要. 综合考虑等离子体中粒子质量、温度及密度, 二次电子效应及非偏置固体的运动速度等因素, 基于气体动理论, 利用粒子的麦克斯韦速度分布函数理论推导得出等离子体环境中非偏置固体表面充电电位一般表达式. 分析了等离子体以及非偏置固体特殊状态下的表达式及一般状态下的表达式, 总结出不同等离子环境、不同运动状态下的表面充电规律. 关键词： 等离子体 非偏置固体 表面充电     

Variational Formulas and Cocycle solutions for Directed Polymer and Percolation Models

We discuss variational formulas for the law of large numbers limits of certain models of motion in a random medium: namely, the limiting time constant for last-passage percolation and the limiting free energy for directed polymers. The results are valid for models in arbitrary dimension, steps of the admissible paths can be general, the environment process is ergodic under spatial translations, and the potential accumulated along a path can depend on the environment and the next step of the path. The variational formulas come in two types: one minimizes over gradient-like cocycles, and another one maximizes over invariant measures on the space of environments and paths. Minimizing cocycles can be obtained from Busemann functions when these can be proved to exist. The results are illustrated through 1+1 dimensional exactly solvable examples, periodic examples, and polymers in weak disorder.     

基于等离子体环境涨落的原子结构计算模型

本文将等离子体核聚变反应截面研究中利用等离子体环境涨落进行修正了的Debye-Hückel屏蔽势推广到计算等离子体中辐射离子束缚态的能级结构. 通过Tsallis参数q的变化,在等离子体辐射离子束缚态能级结构的计算中加入等离子体参数涨落的平均效应,即,等离子体动力学. 具体给出了利用修正的Debye-Hückel屏蔽势对类氦铝束缚态能级结构的计算结果. 结果表明基于这种修正的屏蔽势,自由电子的极化分布具有和线性Debye-Hückel屏蔽势不同的结构. 这种通过等离子体涨落分布对屏蔽势函数进 关键词： 等离子体中的原子结构 等离子体环境涨落 修正了的Debye-Hückel屏蔽势     

在Bohm模式下氘氚燃烧的等离子体温度分布

在一定的等离子体密度分布下,从电子和离子能量输运方程出发,研究了氘氚燃烧下的等离子体温度分布.研究中采用了JET适用的Bohm模式下的热传导系数,考虑了α粒子的反常扩散效应,动态反馈加热.研究结果表明,Bohm模式下的热传导率从等离子体中心到边缘逐渐增加;为了维持氘氚燃烧,必须有动态反馈加热,否则,燃烧将熄灭;α粒子的反常扩散,使得加热效率因子η_α在中心区域小于1,在外层大于1;α粒子的反常扩散越强烈,中心离子温度越高,是由于中心区域的热传导小,电子温度低,反馈加热功率增加的结果;B 关键词：