激光间接驱动聚变内爆流体不稳定性研究

激光间接驱动惯性约束聚变(ICF)内爆过程多层靶球各个界面发生的流体力学不稳定性是影响聚变点火成功的关键因素.为深入了解内爆过程这样不稳定性的发生、发展和它对聚变点火的影响,研制成了研究内爆多介质辐射流体力学过程的高精度二维(局部三维)大型LARED-S程序,并在长期研究实践中不断发展和改善.该程序模拟结果与不稳定性线性和弱非线性解析结果,以及非线性激波管实验结果都很好符合.应用这一程序,进行了大量数值模拟研究,结合理论模型分析,获得了大量流体力学不稳定性发展和演化的重要结果和物理规律认识.获得了具有不同密度、速度、磁场分布的Rayleigh-Taylor(RT)和Kelvin-Helmholtz(KH)不稳定性的线性增长率,以及它们在不可压缩条件下的弱非线性发展的解析解,表明了两者在不同Froude数、密度过渡层厚度、速度剪切层下的竞争关系;通过数值模拟,发现弱预热条件下烧蚀RT不稳定性二次谐波非线性发展导致不稳定增长尖钉(Spike)断裂的重要过程;数值模拟进一步揭露了强预热条件下,烧蚀RT不稳定性非线性发展导致不稳定增长尖钉出现射流状结构,气泡发生加速;还发现强烈的电子热传导使初始单模扰动的KH不稳定性大大削弱,然而却可能使两模扰动非线性发展增大混合尺度.在神光II激光装置上开展了一系列烧蚀RT不稳定性实验.平面靶烧蚀加速飞行轨迹实验结果与LARED-S模拟结果的比较表明腔壁辐射源能流明显小于激光注入孔的辐射能流,且辐射源的非平衡Planckian谱对靶的飞行轨迹和扰动增长有重要影响.实验分别观测到初始小扰动幅度烧蚀RT明显的增长和初始大扰动幅度尖钉变窄和气泡变宽的清晰物理图像.通过提高空间分辨率,实验获得了二次和三次谐波的增长数据.模拟结果与实验结果相符合.神光II激光装置上开展的流体不稳定性实验考核了LARED-S程序的一维和二维计算.在上述理论和实验认识基础上,进行了ICF聚变点火靶物理研究.主要研究靶丸内外表面单球谐模扰动、辐射不对称性、内爆热斑界面不稳定性、黑腔辐射M带以及氘氚(DT)主燃料低阶模面密度不均匀性等物理过程对ICF内爆流体不稳定性的影响.对于ICF间接驱动初始烧蚀层外表面和DT冰内表面的单模粗糙度扰动和辐射驱动不对称性扰动,获得了不稳定性增长规律,提高了热斑界面扰动增长对点火影响和黑腔M带X射线能谱对内爆稳定性影响的物理认识.模拟研究表明DT主燃料面密度不均匀严重影响内爆动能转换为燃料内能的效率和内爆惯性约束时间.研究结果不仅对研究ICF内爆点火有重要参考价值,而且对发生在天体和自然界中流体不稳定性的物理本质理解会有帮助.     

间接驱动内爆物理实验研究进展

激光惯性约束聚变(ICF)研究具有十分重要的实际价值和科学意义,同时也是依赖整体国力的大科学工程.内爆实验,集成理论、制靶、诊断和驱动器等多方面工作,是ICF研究水平的最终体现.我国从20世纪80年代实现激光驱动内爆出中子,到90年代至21世纪头十年实现以冲击压缩为主的近一维内爆,并且惯性压缩开始起作用,直至近期实现中等收缩比、方波驱动、以惯性压缩为主的近一维内爆,内爆实验水平不断进步,内能性能显著提升.随着神光-Ⅲ(SG-Ⅲ)装置的建成,同时在美国点火实验受挫的形势下,我国内爆实验向更高收缩比、更低燃料熵增的点火参数区间迈进,将面临重大机遇与挑战.     

间接驱动惯性约束聚变中的激光等离子体不稳定性

间接驱动惯性约束聚变(Inertial Confinement Fusion,ICF)中,激光能量除了通过逆轫致机制被吸收和传输,还会激发各种参量不稳定性(受激布里渊散射(Stimulated Brillouin Scattering,SBS)、受激拉曼散射(Stimulated Raman Scattering,SRS)、双等离子体衰变(Two-Plasmon Decay,TPD)等),大幅降低激光-靶丸耦合效率并破坏辐射场对称性.因此,激光等离子体不稳定性是实现聚变点火的最大风险之一,研究、理解和抑制以SBS和SRS为主的激光等离子体不稳定性一直在激光聚变研究中占有重要地位.本文从激光(L)、等离子体(P)和不稳定性机制(Ⅰ)这三个方面介绍了激光间接驱动ICF框架下理解和抑制激光等离子体不稳定性(Laser Plasma Instability,LPI)的研究进展和机遇.     

战斗部侧弦攻击舰船内爆毁伤能力评估

建立了舰船内爆毁伤的静爆试验方法,并基于该方法建立了数值模型。通过实验分析与数值模拟,获取了战斗部内爆产生的冲击波超压和破片毁伤参数,分析了冲击波超压对主、临舱室人员的毁伤情况及破片的主要毁伤范围,为战斗部对相同舰船目标的毁伤威力及毁伤评估提供参考依据。     

火焰聚心和激波聚焦诱导爆震波

对几种不同结构形式的爆震发生器进行了数值模拟,来研究激波聚焦和火焰聚心现象、气动特性及其机理。数值计算采用多组分理想气体详细的化学反应机理、二维轴对称非定常流动Navier-Stokes方程来模拟流体动力学和化学动力学过程。数值计算发现用较低的点火能量对射流火焰燃烧器中可燃混合物点火,层流火焰在狭窄管壁作用下加速,射流火焰在轴线上汇聚过程,有利于激波的加强。强激波加速火焰,在多重激波与火焰反复作用下,激波和火焰面之间出现热点,热点迅速放大并形成压力很高的过驱爆震波,而后衰减为稳定的爆震波,不同的激波聚焦腔爆震波的形成过程不同。对数值计算的结果分析得出了起爆距离和稳定爆震距离,为进一步试验提供参考。     

超混沌系统的多变量驱动误差反馈控制同步方法

基于Lyapunov稳定性理论,提出实现连续时间超混沌系统同步的多变量驱动误差反馈控制同步定理,确定了控制参数的范围.同步系统的反馈控制器由线性反馈和非线性反馈2部分组成,并受驱动系统的所有变量驱动.提出采用同步稳定性、同步鲁棒性、同步稳态误差、同步精度、同步建立时间、同步化区域和同步动态特性等描述混沌同步系统性能的7项指标,获得控制参数影响同步系统性能的机理,即控制参数通过改变系统的条件Lya-punov指数而影响系统的同步性能.对R6ssler超混沌系统的数值仿真研究表明:多变量驱动误差反馈同步方法具有不需要分解系统、不需要计算响应系统的条件Lyapunov指数和同步收敛快的特点.     

我国激光惯性约束聚变实验研究进展

介绍国内自2000年以来的激光惯性聚变（inertial confrnementfusion,ICF）实验研究进展,主要内容为神光Ⅱ激光装置上的实验,也对刚建成不久的神光III原型装置上的实验作简要介绍。在神光Ⅱ激光装置上开展了多项的物理实验研究,进行了系列综合和分解实验,获得的主要实验技术指标为：黑腔峰值辐射温度超过二百万度;辐射驱动DT聚变中子产额达10^8和辐射驱动压缩DD燃料密度超过10倍液氘密度;辐射不透明的样品温度接近100eV。在神光Ⅱ装置上得到这些结果表明国内在惯性约束聚变研究方面取得了显著的进步。随着神光Ⅲ原型装置建造的完成,2007年在该装置上进行了首轮物理实验,开展了黑腔物理和辐射内爆物理实验,首轮实验的成功说明神光Ⅲ原型装置已具备实验能力。     

含能固体材料激光点火性能的初步分析

该文建立了含能固体材料激光点火一维数学模型及其数值计算方法,对影响激光点火性能的各个因素进行了初步的分析,得出了一些有益的结论,这将为含能固体材料激光点火性能的试验研究提供补充和指导。     

扬声器低频弱非线性系统的周期振动分析

同时具有恢复力和磁场力的恒压源驱动扬声器非线性系统的动力行为极其复杂.利用多尺度扰动理论对扬声器弱非线性振动系统的周期振动进行数值分析,得出了周期振动的稳定性以及幅频之间的关系.结果表明,只要磁场驱动力存在,调节相应的系数,均可以得到稳定的周期解.     

强激光的靶面均匀辐照和光束匀滑技术

惯性约束核聚变（ICF）的研究对解决当今世界面临的能源危机具有重要意义.为实现ICF聚变点火,要求聚焦到靶面的强激光具有很高的均匀性.分析了实现激光光束匀滑和靶面均匀辐照的几种主要技术方案的原理和方法,得出各技术手段的性能特点及适用条件.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.