共查询到20条相似文献,搜索用时 31 毫秒
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从核爆炸光辐射特点出发, 结合我国中纬度地区大气特点,研究了(0.2~1.2)μm波段大气传输性能。通过实际测量数据分析可知,大气对(0.2~1.2)μm光辐射起主要作用的成分有水蒸气、二氧化碳和臭氧的分子吸收和散射以及气溶胶大粒子的散射。综合考虑这些因素,改进了水平路径传输上(0.2~1.2)μm光辐射大气传输经验方程。计算机仿真结果表明:该方程能体现我国中纬度地区光辐射的传输情况,对(0.4~0.8)μm可见光波段能很好地吻合。将(0.4~0.8)μm波段光辐射大气传输定量计算结果直接应用到基于可见光辐射探测的核爆炸探测子系统中,模拟核爆炸探测,实验结果表明:与传统大气传输计算软件的定性结果相比,该方法的测量精度有明显的提高。 相似文献
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脉冲电流驱动金属丝电爆炸可产生具有较高能量密度的等离子体,并伴随脉冲电磁辐射、强冲击波等效应,广泛应用于Z箍缩、电热化学武器、油气助采等领域;与纯金属相比,合金具备电阻率高、成分可调、相变复杂等特点,在电爆炸效应参数的调控方面具有很大潜力。开展了大气空气介质中铜、镍、铜镍(康铜)丝在微秒时间尺度电脉冲作用下电爆炸实验研究,通过放电参数与自辐射图像诊断,获取电爆炸过程放电参数与时空演变的特性规律,得到脉冲电流作用下合金电爆炸在相变与等离子体方面的特征。实验发现,在电爆炸早期,铜镍合金的高电阻率能够提高能量沉积效率:铜52%、镍74%、铜镍合金78%;而相爆开始后,合金丝负载则更接近纯镍丝负载性能。等离子体通道早期膨胀速率在5 mm/μs量级,随后迅速衰减;合金丝等离子体膨胀时间更久,击穿后平均电阻率上升缓慢,且等离子体辐射与金属爆炸产物在空间尺度上存在关联性。特别地,铜镍合金气溶胶分层同时具有横向和纵向特征(特征尺度10?1 mm),但整体较铜气溶胶更为均匀。 相似文献
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数值研究了平面激波冲击氮气环境中SF6气泡界面的Richtmyer-Meshkov不稳定性,重点关注其中的激波聚焦及射流的产生和发展过程。在入射激波马赫数为1.23的情况下,给出了压力、密度、数值纹影和涡量等物理量的演化图像,定量分析了流场中压力最大值、密度最大值、射流速度、环量和斜压力矩随时间的变化关系。计算结果表明,平面激波冲击SF6气泡过程有很强的聚能效应,在气泡内部靠近下游极点处发生激波近似理想聚焦和点爆炸现象,直接导致出现二次波系以及向下游运动的细长射流结构。相比入射激波,二次波系产生斜压力矩和涡量的能力要弱得多。 相似文献
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Yu. B. Kotov V. D. Popov T. A. Semenova V. F. Fedorov 《Russian Journal of Physical Chemistry B, Focus on Physics》2012,6(1):109-111
The special features of the generation of microwave radiation by a high-power air explosion accompanied by ionizing radiation
are discussed. Coherent pulse caused by asymmetry of the ejection of gamma quanta from a source, incoherent bremsstrahlung
of a partially ionized plasma, incoherent radiation of the shock wave front, and radiation in spectral lines lying inside
air transparency windows are considered. 相似文献
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We predict that coherent electromagnetic radiation in the 1-100 THz frequency range can be generated in crystalline materials when subject to a shock wave or soliton-like propagating excitation. To our knowledge, this phenomenon represents a fundamentally new form of coherent optical radiation source that is distinct from lasers and free-electron lasers. The radiation is generated by the synchronized motion of large numbers of atoms when a shock wave propagates through a crystal. General analytical theory and NaCl molecular dynamics simulations demonstrate coherence lengths on the order of mm (around 20 THz) and potentially greater. The emission frequencies are determined by the shock speed and the lattice constants of the crystal and can potentially be used to determine atomic-scale properties of the shocked material. 相似文献
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It is shown that the ejection of material is explosive, the material emerging as jets moving at 20 km/sec. This supersonic flow produces a shock wave in the plasma. The main source of emission by the evaporated material lies in the jets and in the zones of the shock wave, these determining the character of the spectrum. Spectra recorded with a laser show a strong continuous background, together with line broadening and reversal, as well as absorption lines. The character of the spectrum is independent of the energy density of the laser radiation, but it is very much affected by the air pressure. 相似文献
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本文叙述用光学方法测量了金丝在空气中爆炸冲击波速度,等离子体温度,及金丝引爆2~*药的全过程。研究了EBW雷管的积累区,阈引爆现象及其判断,真爆速与视爆速间的函数关系。提出了该雷管的引爆机理。 相似文献
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We predict that Coulomb explosion of a nanoscale cluster, which is ionized by high-intensity laser radiation and has a naturally occurring spatial density profile, will invariably produce shock waves. In most typical situations, two shocks, a leading and a trailing one, form a shock shell that eventually encompasses the entire cluster. Being the first example of shock waves on the nanometer scale, this phenomenon promises interesting effects and applications, including high-rate nuclear reactions inside each individual cluster. 相似文献
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S. V. Gribin I. I. Komissarova G. V. Ostrovskaya B. I. Spesivtsev V. N. Filippov E. N. Shedova 《Technical Physics》1998,43(8):912-916
A study is made of the penetration of shock waves from air into water. The shock wave in air is generated as a result of dielectric
breakdown induced by pulsed CO2-laser radiation. A combination of the double-exposure shadow method and holographic interferometry is used to measure the
shock-wave parameters. Density and pressure profiles behind the wave front are obtained at different times after onset of
breakdown. It is shown experimentally that as the wave passes through the interface from the air to the water, there is a
fourfold amplification of the pressure in the shock wave front. Estimates of the width of the shock wave front formed in the
water are given in the context of studies of large-scale explosion processes. It is shown that simple empirical dependences,
established in the course of studies of large-scale explosions, are also valid with certain corrections for microscopic laboratory
experiments.
Zh. Tekh. Fiz. 68, 39–43 (August 1998) 相似文献
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The evolution of a spherical gaseous interface accelerated by a plane weak shock wave has been investigated in a square cross section shock tube via a multiple exposure shadowgraph diagnostic. Different gaseous bubbles, i.e., helium, nitrogen, and krypton, were introduced in air at atmospheric pressure in order to study the Richtmyer-Meshkov instability in the spherical geometry for negative, close to zero, and positive initial density jumps across the interface. We show that the bubble distortion is strongly different for the three cases and we present the experimental velocity and volume of the developed vortical structures. We prove that at late times the bubble velocities reach constant values which are in good agreement with previous calculations. Finally, we point out that, in our flow conditions, the gaseous bubble motion and shape are mainly influenced by vorticity and aerodynamic forces. 相似文献
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Ashish V. Shelke Bhuvaneshwar Gera Naresh K. Maheshwari Ram K. Singh 《Combustion Theory and Modelling》2019,23(3):387-413
Occurrences of fireball close to plant buildings due to the release of flammable hydrocarbon fuel caused by the formation of fuel vapour cloud poses severe safety concerns. On the availability of potential ignition source, the induced fireball would cause the damage to the structures of nuclear power plant by direct contact, radiation and/or convection of hot combustion products through the opening of air intakes and ducts. In the present paper, the accidental/ experimental observations and theoretical studies of fireball are summarised. Computational fluid dynamics (CFD) analyses have been carried out to study the behaviour of fireball using OpenFOAM CFD software. The parametric studies are conducted by varying the mass of fuel, inlet velocity and inlet diameter. The new correlations for fireball diameter and duration have been proposed based on the parametric studies using CFD simulations. The fireball with a larger amount of fuel releases the heat slower and for a longer duration. The high heat released rate (HRR) is observed in case of a larger inlet diameter used for the same mass. The incident radiation from the fireball is calculated at different locations to assess thermal hazard. Analysis performed show that various parameters like fireball diameter, duration and the radiative flux falling at different locations can be predicted well using CFD code. 相似文献
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S. I. Gerasimov 《Technical Physics》2017,62(12):1799-1804
Background oriented schlieren method is applied in diagnostics of shock waves in air. The method can be used for visualization of shock waves that are generated after explosion or due to motion at ultrasonic speeds. Experimental data make it possible to observe propagation of a shock wave in space, estimate the asymmetry of energy liberation in explosion, and determine parameters of shock wave. 相似文献
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