共查询到20条相似文献,搜索用时 58 毫秒
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尹强 《工程物理研究院科技年报》2009,(1):31-32
瑞利-泰勒(R—T)流体力学不稳定性是制约惯性约束聚变(ICF)实验点火的重要因素之一。研究证明,通过在有机薄膜或低密度泡沫上人为引入面密度扰动可以模拟靶丸表面的不完整性,通过测量激光对靶烧蚀过程中靶密度扰动的时空分布非线性增长,可估算R—T不稳定性的大小。关于调制薄膜制备的方法国内目前仅有数篇报道,但有关薄膜泡沫复合调制靶的制备还未见相关文献报道。 相似文献
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研究对比了激光直接辐照、聚焦辐照以及激光等离子体辐照三种辐照方式下,洋葱表皮细胞的烧蚀特征,并基于激光辐照的热力学特性对细胞的温升以及相变过程进行分析。观察发现: 直接辐照对细胞的杀伤效果很不明显;聚焦辐照会引起焦点附近细胞的断裂以及脱水;激光等离子体辐照作用下,细胞会呈现大面积的去除,断裂边缘粗糙,且细胞层有叠加现象。理论分析发现,激光等离子体具有热效应、辐射电离及冲击波效应等,会增加激光脉冲能量到细胞的沉积、以及对细胞冲击剥离等,从而会大大增加细胞的杀伤范围和效率,可用于对细胞进行大面积杀伤。 相似文献
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通过电火花加工技术,采用含碳较高的煤油作为电介质,利用导电性能及加工性能较好的紫铜作电极材料,实现了SiO2/CH/Au复合黑腔侧表面方形诊断孔的精密加工。采用OLYMPUS STM6测量显微镜对诊断孔尺寸,结果表明:孔的尺寸加工精度可控制在±10μm内,同一电极加工的诊断孔尺寸一致性可控制在±5μm内。采用扫描电镜能谱分析SiO2/CH/Au加工导电层的成分,结果表明:电火花加工过程中,由于电介质分解生成游离态的碳以及电极材料铜熔融后沉积在CH和SiO2层表面,形成辅助导电层。通过加工辅助导电层,产生的瞬时高温使SiO2和CH层熔融气化,从而实现对绝缘层的加工。 相似文献
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M.J.A. Rickard J.M. Hall E.L. Petersen 《Proceedings of the Combustion Institute》2005,30(2):1915-1923
Ignition delay time and species profile measurements are reported for the combustion of C2H2/O2/Ar mixtures with and without the addition of silane for temperatures between 1040 and 2320 K and pressures near 1 atm. Characteristic times, namely ignition time and time to peak, were determined from the time histories of CH* (A2Δ → X2Π) and OH* (A2Σ+ → X2Π) emission near 430 and 307 nm, respectively. For the cases without silane, there is good agreement between the present data and some recent acetylene oxidation results. Small SiH4 additions (<10% of the fuel) reduced the ignition time in stoichiometric mixtures by as much as 75% for shocks near 1800 K. Similar reductions were seen in the fuel-lean mixture, although the effect was less temperature dependent. Several detailed chemical kinetics mechanisms of hydrocarbon oxidation were compared to the ignition delay-time data and species profiles for C2H2/O2/Ar mixtures without silane. All models under-predicted ignition time for the 98% diluted stoichiometric mixture but matched the fuel-lean ignition data somewhat better. Two of the models displayed the shift in activation energy at lower temperatures seen in the data, although no one model was able to reproduce all ignition times over the entire range of mixtures and conditions. 相似文献
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Collisions and interactions of dispersive shock waves in defocusing (repulsive) nonlinear Schrödinger type systems are investigated analytically and numerically. Two canonical cases are considered. In one case, two counterpropagating dispersive shock waves experience a head-on collision, interact and eventually exit the interaction region with larger amplitudes and altered speeds. In the other case, a fast dispersive shock overtakes a slower one, giving rise to an interaction. Eventually the two merge into a single dispersive shock wave. In both cases, the interaction region is described by a modulated, quasi-periodic two-phase solution of the nonlinear Schrödinger equation. The boundaries between the background density, dispersive shock waves and their interaction region are calculated by solving the Whitham modulation equations. These asymptotic results are in excellent agreement with full numerical simulations. It is further shown that the interactions of two dispersive shock waves have some qualitative similarities to the interactions of two classical shock waves. 相似文献
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在“神光Ⅱ”的三倍频装置上进行实验,利用北四路激光注入半腔靶后接不同密度、不同厚度的CH(C66H12,聚4甲基1戊烯)发泡材料,研究x射线辐射在低密度CH泡沫中的超声速传播问题,对x射线辐射的多个能点(80,250和400eV)的传播时间、传播速度、输运管壁收缩过程、时间能谱和辐射温度等进行了测量,获得了10倍的超声速传输的速度,并采用辐射输运“漏水管模型”对实验结果进行了简要分析,结果基本相符 .
关键词:
辐射输运
超声速热波
CH发泡 相似文献
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Kevin Zumbrun 《Physica D: Nonlinear Phenomena》2010,239(13):1180-1187
Combining the work of Serre and Zumbrun, Benzoni-Gavage, Serre, and Zumbrun, and Texier and Zumbrun, we propose as a mechanism for the onset of cellular instability of viscous shock and detonation waves in a finite-cross-section duct, the violation of the refined planar stability condition of Zumbrun-Serre, a viscous correction of the inviscid planar stability condition of Majda. More precisely, we show for a model problem involving flow in a rectangular duct with artificial periodic boundary conditions that transition to multidimensional instability through violation of the refined stability condition of planar viscous shock waves on the whole space generically implies for a duct of sufficiently large cross-section, a cascade of Hopf bifurcations involving more and more complicated cellular instabilities. The refined condition is numerically calculable as described by Benzoni-Gavage-Serre-Zumbrun. 相似文献
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O.G. Penyazkov K.A. Ragotner A.J. Dean B. Varatharajan 《Proceedings of the Combustion Institute》2005,30(2):1941-1947
Ignition times and autoignition modes for propane–air mixtures have been studied behind reflected shock waves. Experiments were performed over temperatures between 1000 and 1750 K, pressures between 2 and 20 atm, and equivalence ratios of = 0.5, 1.0, and 2.0. Ignition delay times were determined using pressure measurements, C2 emission profiles, and luminosity measurements in the visible spectrum (380–680 nm). Empirical correlations for ignition time for low temperature (1000–1300 K) and high temperature (1300–1800 K) ranges have been deduced from the experimental data. Different autoignition modes of the mixture (strong, transient, and weak) were identified by comparing velocities of reflected shock wave at different distances from the reflecting wall. 相似文献
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The nonlinear propagation of dust ion-acoustic (DIA) shock waves is studied in a charge varying dusty plasma with electrons having kappa velocity distribution. We use hot ions with equilibrium streaming speed and a fast superthermal electron charging current derived from orbit limited motion (OLM) theory. It is found that the presence of superthermal electrons does not only significantly modify the basic properties of shock waves, but also causes the existence of shock profile with only positive potential in such plasma with parameter ranges corresponding to Saturn?s rings. It is also shown that the strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. 相似文献
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The interplay among the cavitation structures and the shock waves following a nanosecond laser breakdown in water in the vicinity of a concave surface was visualized with high-speed shadowgraphy and schlieren cinematography. Unlike the generation of the main cavitation bubble near a flat or a convex surface, the concave surface refocuses the emitted shock waves and causes secondary cavitation near the acoustic focus which is most pronounced when triggered by the shock wave released during the first main bubble collapse. The shock wave propagation, reflection from the concave surface and its scattering on the dominant cavity is clearly resolvable on the shadowgraphs. The schlieren approach revealed the pressure build up in the last stage of the collapse and the first stage of the rebound. A persistent low-density watermark is left behind the first collapse. The observed effects are important wherever cavities collapse near indented surfaces, such as in cavitation peening, cavitation erosion and ophthalmology. 相似文献
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Gouranga C. Nayak 《Annals of Physics》2010,325(3):682-3898
In this paper, we prove factorization of fragmentation function in non-equilibrium QCD by using Schwinger-Keldysh closed-time path integral formalism. We use the background field method of QCD in a pure gauge in path integral approach to prove factorization of fragmentation function in non-equilibrium QCD. Our proof is valid in any arbitrary gauge fixing parameter α. This may be relevant to study hadron production from quark-gluon plasma at high energy heavy-ion colliders at RHIC and LHC. 相似文献