压缩氘氚球的热核燃烧特性研究

本文利用LARED-S程序模拟了等密度和等压力条件下压缩氘氚球的热核反应燃烧过程.对于等密度模型,模拟了两个具体算例,与国外计算结果进行了比较,验证了程序的可靠性.对于等压力模型,利用数值模拟给出了热核反应燃烧与压缩氘氚球初始状态之间的关系曲线,分析发现,氘氚装量、压力和主燃料密度的增加有利于提高热核反应放能和燃耗,中心热斑的温度和面密度分别达到70—80 MK和3—4 kg·m^-2时热核反应才有显著的放能,提高主燃料密度,可以适当放宽对中心热斑的点火要求.最后对实际点火靶进行了数值模拟并且与等压力模拟计算结果进行了比较分析. 关键词： 压缩氘氚球 等密度模型 等压力模型 热核反应聚变     

Coupling between velocity and interface perturbations in cylindrical Rayleigh–Taylor instability

Rayleigh–Taylor instability(RTI) in cylindrical geometry initiated by velocity and interface perturbations is investigated analytically through a third-order weakly nonlinear(WN) model. When the initial velocity perturbation is comparable to the interface perturbation, the coupling between them plays a significant role. The difference between the RTI growth initiated only by a velocity perturbation and that only by an interface perturbation in the WN stage is negligibly small. The effects of the mode number on the first three harmonics are discussed respectively. The low-mode number perturbation leads to large amplitudes of RTI growth. The Atwood number and initial perturbation dependencies of the nonlinear saturation amplitude of the fundamental mode are analyzed clearly. When the mode number of the perturbation is large enough,the WN results in planar geometry are recovered.     

Weakly Nonlinear Rayleigh–Taylor Instability in Cylindrically Convergent Geometry

The Rayleigh–Taylor instability(RTI) in cylindrical geometry is investigated analytically through a second-order weakly nonlinear(WN) theory considering the Bell–Plesset(BP) effect. The governing equations for the combined perturbation growth are derived. The WN solutions for an exponentially convergent cylinder are obtained. It is found that the BP and RTI growths are strongly coupled, which results in the bubble-spike asymmetric structure in the WN stage. The large Atwood number leads to the large deformation of the convergent interface. The amplitude of the spike grows faster than that of the bubble especially for large mode number m and large Atwood number A. The averaged interface radius is small for large mode number perturbation due to the mode-coupling effect.     

压缩氘氚球的热核燃烧特性研究

本文利用LARED-S程序模拟了等密度和等压力条件下压缩氘氚球的热核反应燃烧过程.对于等密度模型,模拟了两个具体算例,与国外计算结果进行了比较,验证了程序的可靠性.对于等压力模型,利用数值模拟给出了热核反应燃烧与压缩氘氚球初始状态之间的关系曲线,分析发现,氘氚装量、压力和主燃料密度的增加有利于提高热核反应放能和燃耗,中心热斑的温度和面密度分别达到70—80 MK和3—4 kg·m^-2时热核反应才有显著的放能,提高主燃料密度,可以适当放宽对中心热斑的点火要求.最后对实际点火靶进行了数值模拟并且与等压力模拟计算结果进行了比较分析.     

等价无穷小量的性质及应用

在高等数学中，等价无穷小量有一个重要性质，即性质１设ｌｉｍｘ→ｘ０α＝０，ｌｉｍｘ→ｘ０β＝０，且α～α１，β～β１，ｌｉｍｘ→ｘ０α１β１存在，则ｌｉｍｘ→ｘ０αβ＝ｌｉｍｘ→ｘ０α１β１．利用这一性质可通过等价无穷小量替换法求００型未定式的极限．...     

神光Ⅱ装置上辐射驱动瑞利-泰勒不稳定性实验北大核心CSCD

在神光Ⅱ装置上开展了辐射驱动RT不稳定性的一系列实验,获得了不同初始扰动幅度、不同扰动波长、不同材料样品等条件下辐射烧蚀RT不稳定性增长的高时空分辨背光图像,特别是在大初始扰动幅度样品实验中获得了扰动增长的清晰图像,观察到了扰动增长从线性区到非线性区的过渡过程,二次和三次谐波的产生和发展清楚可见。充实了数值模拟程序考核的实验数据库,对间接驱动ICF点火靶设计和研究具有重要作用。     

激光辐照金(Au)圆盘靶的二维数值模拟

简要描述了激光在等离子体中传播的三维光路方程的追踪解法,同时对电子热传导中的热流以及非平衡束缚电子占据概率速率方程组给出了一种简便解法.应用这些方法和新近发展的LARED H程序,对激光辐照金(Au)圆盘和圆环靶进行了二维模拟,给出了靶等离子体的合理的二维行为特征.     

Rayleigh-Taylor和Richtmyer-Meshkov不稳定性的FCT方法数值模拟

介绍了二维流体力学不稳定性程序的FCT数值方法,数值模拟Rayleigh-Taylor和Richt-myer-Meshkov流体不稳定性,在线性阶段,与线性理论符合很好;在非线性阶段,与俄罗斯激波管实验的计算结果符合很好。计算结果表明:FCT方法有较高计算精度,给出了不稳定性发展的好的图象,适合于ICF烧蚀和内爆流体不稳定性问题的计算。     

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.