等离子体中氖输运及辐射特性模拟

通过假定一定的温度和密度分布,数值求解了一维等离子体连续性方程,获得了杂质氖电离态分布及辐射功率随空间位置和时间的变化.计算结果显示,在杂质注入时间较短时,由于离子输运及各种损失机制,总杂质密度在空间分布尚未达到平衡,电离态离子主要分布在等离子体周边,完全电离离子所占份额很小.当时间达到0.2s时,氖在等离子体中完全达到平衡状态,体积辐射功率趋于一个稳定的数值.达到平衡状态后,芯部一个很大范围内氖杂质主要以Ne 10离子型态存在,辐射功率以轫致辐射为主,因此辐射功率较小.辐射功率在空间的分布随时间变化较小,主要分布在等离子体周边及边界层一个狭小的辐射带内,说明氖引起的辐射主要由低电离态离子引起.     

某些类氖离子和类镍离子等离子体状态对应关系的研究

利用一维拉格朗日流体动力学程序Med103详细研究了产生类镍Ag,Cd,In,Sn, Sb离子和类氖Fe,Co,Ni,Cu,Zn离子的等离子体状态.通过对电子温度、离子丰度、离子数密度等状态参量的分析比较，得到了这两类等离子体状态之间的对应关系.即类镍银的等离子体状态与类氖铁 的相近，类镍镉的与类氖钴的相近，依次类推.利用这一对应关系可以方便地由类氖机理x射线激光的等离子体状态来对相应元素的类镍x射线激光的等离子体状态进行判断. 关键词： 类氖 类镍 等离子体状态 x射线激光     

电子非广延分布的多离子磁化等离子体鞘层特性

等离子体磁化鞘层在半导体加工、材料表面改性、薄膜沉积等方面都发挥着重要作用.在等离子体实验和放电应用中,常存在由两种以上离子组成的多离子等离子体;对于长程相互作用的等离子体系统,非麦克斯韦分布的电子可通过Tsallis的非广延分布来描述.本文针对多离子等离子体鞘层建立一维空间坐标三维速度坐标的流体模型,假设鞘层中电子速度服从非广延分布,本底氦离子和不同种类的杂质离子在有一定倾斜角度的磁场中被磁化,通过数值模拟探究了非广延参量、杂质离子及斜磁场对多离子磁鞘中离子的数密度、速度、壁面电势和离子动能等物理量的影响.结果表明,在氦氢或氦氩混合等离子体鞘层中,随着非广延参量增大,离子沿垂直壁方向的速度减小,鞘层中离子、电子数密度均减小,鞘层厚度减小,壁面处离子动能减小;当杂质离子浓度增大时,壁面处离子动能与离子种类无关.随着磁场强度的增大,氦离子数密度和沿垂直壁方向的速度在鞘边出现起伏,且波动幅度随着非广延参量的减小而增大,而重离子则无明显的波动.此外,还分析了杂质离子种类和浓度对鞘层相关特性的影响.     

多电子原子的电离过程

在电晕近似下给定等离子体的温度和密度,采用离子模型用数值计算方法求解了电离度方程组。给出Si~(14)、Ar~(18)、Ti~(22)、Fe~(26)、Ge~(32)和Kr~(36)等六种元素的离子丰度、离化度和电离度等特征量的数值结果,为研究类氖离子的3P-3S反转提供了类氖离子丰度的数值     

毛细管放电条件下类氖序列原子参量计算与分析

利用多组态求解相对论性的Hartree-Fock-Roothan方程(HFR)方法计算了类氖离子(Z=13～27)2s^22p^5—2s^22p^53s能级之间跃迁的原子参量,包括类氖氩激光系统的能级,振子强度,自发辐射衰变速率,能级寿命,电子碰撞激发截面及电子碰撞激发速率系数等。以类氖氩离子为例,分析了等离子体内46．9nm激光跃迁的粒子数反转的形成及谱线放大过程,讨论了其它几条谱线产生增益的可能性,分析了激光线振子强度随核电荷数的变化规律。根据获得的原子参量,计算了利用毛细管放电产生类氖氩和类氖氪x射线激光的放电参量,其中类氖氩毛细管放电的初始压强的范围为30~90Pa,放电电流峰值为10～50kA。理论计算结果为类氖氩x光激光实验分析,深入研究等离子体反转动力学,激光增益的估算及理论方案设计等提供了基本数据。     

类氢氖基态电离势随等离子体温度密度的变化

采用自洽场离子球模型,研究类氢氖基态1s的电离势随等离子体电子温度及电子密度的变化规律,计算得到基态电离势的百分偏移量随等离子体电子密度的变化关系,拟合结果表明两者的对数值满足很好的线性关系.该结果对计算等离子体电离态分布及光谱模拟具有一定意义.     

杂质离子对等离子体边界参量的影响

采用一维流体模型研究了含有杂质离子的等离子体与器壁材料相互作用给边界等离子体参量带来的影响.通过数值模拟,研究了分别选用碳和钨作为器壁材料时,器壁温度不同情形下热发射产生的电子对等离子体器壁电势、电场强度、热发射电子流以及沉积器壁离子动能流的影响.研究结果发现,当面向等离子体材料表面温度升高时,器壁电势和热发射产生的电流将增加,器壁电场强度和离子沉积器壁动能流则会减小,并且钨作为器壁材料要比碳作为器壁材料对于等离子体边界参量影响更明显.此外,研究了钨作为器壁材料时,碳杂质离子（浓度和电荷数）对等离子体器壁参量的影响.     

高度电离的锗激光等离子体X射线谱的辨认

本文结合理论计算得到的锗类钠、类氖、类氟、类氧离子的振子强度,对平面晶体谱仪拍摄的锗激光等离子体X射线谱,波长在6～10(?)范围内的40多条谱线进行了分类辨认.     

第一壁泄漏杂质的分布计算

以数值计算法计算了第一壁冷却剂泄漏氦杂质在等离子体中的分布,氦分布的峰值在SOL(Scrape-ofLayer)区。当要求等离子体中心的氦浓度小于5%时,允许的最大泄漏率N_max约为0.35×10^-3Mol/s,允许的最大裂纹尺寸长约为3.1mm,宽约为0.63mm。影响杂质分布和浓度的主要因素有壁温、等离子体边缘温度、密度和SOL区的温度密度长度。壁温越低、等离子体边缘温度越低、密度越高、温度和密度长度越大,则中心杂质浓度越小,且杂质分布峰值越接近第一壁。     

X射线激光器研究初步结果

利用等离子体复合抽运X射线激光器模型和四能级速率方程,我们导出了在激光等离子体体系中发生位子数反转所须满足的条件。在这个基础上,通过分析不同结构靶的等离子体性质,我们发现当激光辐照复合镁靶时,在镁的类氦离子1S4P-1S3P能级间的粒子数反转。另外,我们在中等Z系例元素等离子体中也得到类氖离子系统粒子数反转证据并证明这些现象主要是由等离子体复合而引起的。 上述实验证明了我们的理论计算结果。     

Spin Hall effect induced by resonant scattering on impurities in metals

The spin Hall effect is a promising way for transforming charge currents into spin currents in spintronic devices. Large values of the spin Hall angle, the characteristic parameter of the yield of this transformation, have been recently found in noble metals doped with nonmagnetic impurities. We show that this can be explained by resonant scattering off impurity states split by the spin-orbit interaction. By using as an example copper doped with 5d impurities we describe the general conditions and provide a guide for experimentalists for obtaining the largest effects.     

Fast photoluminescence decay processes of doped ZnO phosphors

Lifetime measurements have been carried out for ZnO doped with killer impurities (Fe, Co or Ni) having doping concentrations 0.05 to 1.00% by weight using a pulsed UV laser (nitrogen laser) as the excitation source having a short pulse width and a high photon flux density. The high photon flux density of the laser is very useful to excite the short-lived shallow trapping states which otherwise would be impossible to excite. Fast photoluminescence emission in the microsecond time domain has been obtained due to killer impurities at room temperature. The effect of killer dopants as well as the effect of their concentrations on lifetime values has been observed. Other optical parameters such as trap depth and decay constant are also reported in the present context. Lifetime values are found to be in the microsecond time domain and a reverse trend is obtained with increase in concentration of killer impurities. PACS 78.55.-m; 78.55.Ap; 78.66.Db; 78.66.Hf     

Quantum entanglement in elliptical quantum corrals

Quantum corrals present interesting properties due to the combination of confinement and, in the case of elliptical corrals, to their focalizing properties. We study the case when two magnetic impurities are added to the non-interacting corral, where they interact via a superexchange AF interaction J with the surface electrons in the ellipse. Previous results showed that, when both impurities are located at the foci of the system, they experience an enhanced magnetic interaction, as compared to the one they would have in an open surface. For small J and even filling, they are locked in a singlet state, which weakens for larger values of this parameter. When J is much larger than the hopping parameter of the electrons in the ellipse, both spins decorrelate while forming a local singlet with the electrons of the ellipse, thus presenting a confined RKKY–Kondo transition.We interpret this behaviour by means of the von Neumann entropy between the localized impurities and the itinerant electrons of the ellipse: for small J the entropy is nearly zero while for large J it is maximum. In addition, the local density of states provides us with a concrete experimental tool for detecting the Kondo regime.     

Evidence of neutral impurity scattering in mercury sulphide (α-HgS) in the temperature range 77–300 K correlation with chemical analysis

Five natural or synthetic trigonal HgS single crystals have been studied by transport experiments in the temperature range 77–300 K. The classical d.c. technique has been used to measure the Hall coefficient and the resistivity. The temperature dependence of the free carrier density in the conduction band associated to a chemical analysis have brought to light the presence of neutral donor impurities with a density much larger than the ionized ones, which has led us to consider the existence of neutral impurity scattering even at room temperature.A detailed study of the mobility has shown that, among the four possible and efficient scattering processes, (neutral impurities, ionized impurities, acoustical phonons and optical polar modes), the most efficient in the whole experimental temperature range is the neutral impurities one. However, at room temperature, the polar optical mode becomes comparable to the previous one. The agreement obtained between the experimental values of the mobility and the calculated ones by taking into account these four scattering modes is very good in the whole temperature range.So for the first time an explanation is given for the rather low value of the mobility in mercury sulphide. This explanation of the mobility behaviour is in good agreement with the results of the chemical analysis which shows in HgS-α the presence of impurities very much larger than that of the ionized impurities one.     

Hyperfine Fields of Light Interstitial Impurities in Ni

The magnetic hyperfine interaction of light interstitial impurities in Ni have been studied by means of the Korringa–Kohn–Rostoker (KKR) band structure method. This method allows to deal with the impurity problem by solving the corresponding Dyson equation for the Green’s function. It also allows to account for lattice relaxations. For this purpose a new technique was developed that allows to handle in principle arbitrary lattice distortions. Corresponding calculations have been performed for the magnetic hyperfine fields of the light interstitial impurities H to Ne in Ni. By minimising the force on the nearest neighbour host atoms their equilibrium position was determined. The resulting hyperfine fields for the equilibrium configuration are found to be in rather good agreement with available experimental data.     

Mechanism of strong resonant 1LO Raman scattering

The interaction of electrons with impurities and the quasi-elastic scattering of electrons by acoustic phonons highly enhances the efficiency of resonant 1 LO Raman scattering. As a result, for a wide range of parameter values the efficiency of resonant scattering becomes rather strong and does not depend on the strength of interaction of electrons with the impurities and acoustic phonons, and on the impurity concentration.     

Some new progress on the light absorption properties of linear alkyl benzene solvent

Linear alkyl benzene(LAB) will be used as the solvent in a liquid scintillator mixture for the JUNO antineutrino experiment. Its light absorption properties should therefore be understood prior to its effective use in the experiment. Attenuation length measurements at a light wavelength of 430 nm have been performed on samples of LAB prepared for the JUNO experiment. Inorganic impurities in LAB have also been studied for their possibilities of light absorption in our wavelength of interest. In view of a tentative plan by the JUNO collaboration to utilize neutron capture with hydrogen in the detector, we also present in this work a preliminary study on the carbon–hydrogen ratio and the attenuation length of the samples.     

A面(11-20)ZnO薄膜中杂质的偏振PL谱研究

本文通过分析A面(11-20)ZnO薄膜的低温PL(光致发光)光谱偏振特性来研究ZnO光致发光谱中杂质峰的来源。低温(4 K)下观察到476、479 nm两处新的杂质峰以及390 nm处激子峰,根据两个杂质峰的偏振特性,初步判定476nm峰来源于氧空位能级到价带轻空穴的跃迁,479 nm峰来源于氧空位价带重空穴的跃迁。     

Transformation of Radiation-Induced Molecular Point Defects and Color Centers in LiF Crystals under Influence of Light

Physics of the Solid State - The influences of UV light and integral light pulses from lamps on γ-irradiated LiF crystals with impurities of hydroxyl and magnesium ions have been investigated....     

全场数字化测量光弹性等倾角的五步彩色相移法

通过把相移法与光学彩色信息图像处理技术相结合 ,提出了一种确定全场光弹性等倾角的五步彩色相移法。模型置于白光照射下 ,在起偏镜与分析镜不同设置的平面偏振光场中 ,用彩色数码照相机分别采集五幅等色线与等倾线相耦合的条纹图 ,根据相移法基本原理 ,就可以确定在 0～π/2范围内的等倾角。经过对径压缩圆盘的检验 ,实验结果与理论完全相符。该方法改进了单色光相移法的不足 ,对实验应力分析及其在工程结构强度设计中的应用将起积极的促进作用