Rayleigh–Taylor instability at spherical interfaces of incompressible fluids

Rayleigh–Taylor instability(RTI) of three incompressible fluids with two interfaces in spherical geometry is derived analytically. The growth rate on the two interfaces and the perturbation feedthrough coefficients between two spherical interfaces are derived. For low-mode perturbation, the feedthrough effect from outer interface to inner interface is much more severe than the corresponding planar case, while the feedback from inner interface to the outer interface is smaller than that in planar geometry. The low-mode perturbations lead to the pronounced RTI growth on the inner interface of a spherical shell that are larger than the cylindrical and planar results. It is the low-mode perturbation that results in the difference between the RTI growth in spherical and cylindrical geometry. When the mode number of the perturbation is large enough, the results in cylindrical geometry are recovered.     

一种利用等离子体X射线激光输出对称性测量X射线多层膜镜反射率的方法

从理论上论证了利用平板靶X射线激光两个输出端光强对称的特性来测量X射线多层膜镜反射率的测量方法.针对实验布局中等离子体对X射线激光吸收可能造成测量误差的情况,以保证测量结果千分之一的精确度为基准,从理论上计算获得该方法对不同波长X射线激光的实验布局要求.并依此要求对制得的Mo/Si、Mo/Mg镜的反射率进行了实验测量.     

不同含水量砂岩的中红外光谱特征与预测模型研究

水对岩石具有软化、溶蚀等作用,准确预测岩石的含水量对岩土工程的地下深部开采至关重要。该文将中红外光谱技术应用于砂岩的含水量分析,研究了不同砂岩样品的中红外光谱特征与其含水量之间的关系。通过多种预处理方法提取有效特征向量,构建了针对砂岩含水量的中红外光谱预测模型。结果表明,多元散射校正+偏最小二乘法、归一化特征向量提取+随机森林及一阶微分+支持向量机3种模型在测试集上预测的含水量与实测值之间的相关系数（R2）分别为0.985、0.995和0.951,均方根误差分别为0.074、0.022和0.137,即特征向量提取+随机森林的预测模型效果最佳。该方法通过中红外光谱技术实现了砂岩含水量的无损、快速分析,为地质工程中砂岩的水分预测提供了参考。     

非相对论线偏振激光下的J×B加热

利用解析的方法研究了非相对论线偏振激光与等离子体相互作用中的J×B加热吸收机理，建立了一种包含两类有质动力效应在内的自洽理论.探讨了密度轮廓修正下的J×B加热机理，给出了相应的吸收系数随激光场强度变化的关系曲线.研究发现，当激光场强度A₀=20时，J×B加热所导致的吸收系数f_abs约为2.8%. 关键词： J×B加热 有质动力 密度轮廓     

Mode coupling in nonlinear Kelvin--Helmholtz instability

This paper investigates the interaction of a small number of modes in the two-fluid Kelvin-Helmholtz instability at the nonlinear regime by using a two-dimensional hydrodynamic code. This interaction is found to be relatively long range in wave-number space and also it acts in both directions, i.e. short wavelengths affect long wavelengths and vice versa. There is no simple equivalent transformation from a band of similar modes to one mode representing their effective amplitude. Three distinct stages of interaction have been identified.     

激光等离子体X射线源的应用

激光等离子体作为X射线光源，具有光源体积小、亮度高、脉冲短等优点。因此，激光等离子体X射线光源在时间分辨诊断测量等方面具有重要的应用。文章简单介绍了这种光源在软X射线投影光刻技术、医学成像、晶体研究以及惯性约束核聚变（ICF）研究等方面的应用。这四个方面分别属于信息，生物，材料和能源等四个科学领域。作者的目的在于让这些科研领域及其对应工业界的研究同行了解我们的工作，从而能够实现跨学科、跨领域的合作。     

Analytical model for Rayleigh—Taylor instability in conical target conduction region

This work builds an isobaric steady-state fluid analytical-physical model of the plasma conduction region in a conical target. The hydrodynamic instability in the double-cone ignition scheme^[21] for inertial confinement fusion (ICF) proposed by Zhang is studied with the built model. With this idealized model, the relevant parameters, such as density, temperature, and length of the plasma in the conduction region of the conical target under long-pulse conditions are given. The solution of the proposed analytical model dovetails with the trend of the numerical simulation. The model and results in this paper are beneficial for discussing how to attenuate Rayleigh—Taylor instability in ICF processes with conical and spherical targets.     

金属嵌入对三角晶格耦合腔光波导群速度的影响

利用多重散射法和时域有限差分法理论,研究了二维三角晶格光子晶体耦合腔光波导的传输特性.理论模拟结果表明,在耦合腔光波导中嵌入半径很小的理想金属丝,能有效地减弱相邻点缺陷之间的耦合强度,实现了比真空中光速小三个数量级的群速度.     

任意Atwood数Rayleigh-Taylor和 Richtmyer-Meshkov 不稳定性气泡速度研究

本文将Layzer气泡模型推广到任意界面Atwood数情形,得到了自洽的微分方程组.该模型描述了气泡从早期的指数增长阶段到气 泡以渐近速度上升的非线性阶段的发展过程,给出了Rayleigh-Taylor(RT)和Richtmyer-Meshkov(RM)不稳定性的二维和 三维气泡速度渐近解,还求出了二维和三维RT不稳定性气泡顶点附近速度的解析解.