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Surface-wave gas discharges sustained under the conditions of a diffusion controlled regime are studied on the basis of the fluid plasma model. The self-consistent behaviour of the plasma density and of the field intensity along the discharge length is obtained. It is shown that the nonlinearity in the particle balance equation due to stepwise ionisation determines the plasma density in terms of the field intensity and ensures self-consistent behaviour of the wave ? discharge characteristics in a diffusion controlled regime. 相似文献
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We develop the nonlinear theory of dust voids [Phys. Rev. Lett. 90 (2003) 075001], focusing particularly on effects of the ionization, to investigate numerically the void evolution under cylindrical coordinates [Phys. Plasmas 13 (2006) 064502]. The ion velocity profile is solved by a more accurate ion motion equation with the ion convection and ionization terms. It is shown that the differences between the previous result and the one obtained with ionizations are significant for the distributions of the ion and dust velocities, the dust density, and etc., in the void formation process. Furthermore, the ionization can slow down the void formation process effectively. 相似文献
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FANQuan-Lin WEIFeng-Si FENGXue-Shang 《理论物理通讯》2003,40(2):247-252
The formation med2aniRm of the interplanetary magnetic cloud (MC) boundaries is numerically investigated by simulating the interactions between an MC of some initial momentum and a local interplanetary current sheet.The compressible 2.51:) MHD equations are solved. R~sults show that the magnetic reconnection process is a possible formation mechanism when an MC interacts with a surrounding current sheet. A number of interesting features are found. For instance, the front boundary of the MCs is a magnetic reconnection boundary that could be caused by a driven reconnection ahead of the cloud, and the tail boundary might be caused by the driving of the entrained flow as a result of the Bernoulli principle. Analysis of the magnetic field and plasma data demonstrates that at these two boundaries appear large value of the plasma parameter β, clear increase of plasma temperature and density, distinct decrease of magnetic magnitude, and a transition of maguetic field direction of about 180 degrees. The outcome of the present simulation agrees qualitatively with the observational results on MC boundary inferred from IMP-8, etc. 相似文献
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The formation mechanism of the interplanetary magnetic cloud (MC) boundaries is numerically investigatedby simulating the interactions between an MC of some initial momentum and a local interplanetary current sheet.The compressible 2.5D MHD equations are solved. Results show that the magnetic reconnection process is a possibleformation mechanism when an MC interacts with a surrounding current sheet. A number of interesting features arefound. For instance, the front boundary of the MCs is a magnetic reconnection boundary that could be caused by adriven reconnection ahead of the cloud, and the tail boundary might be caused by the driving of the entrained flowas a result of the Bernoulli principle. Analysis of the magnetic field and plasma data demonstrates that at these twoboundaries appear large value of the plasma parameterβ, clear increase of plasma temperature and density, distinctdecrease of magnetic magnitude, and a transition of magnetic field direction of about 180 degrees. The outcome of thepresent simulation agrees qualitatively with the observational results on MC boundary inferred from IMP-8, etc. 相似文献
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WANG Hong-Yu XIE Bai-Song 《理论物理通讯》2006,46(3):563-567
We propose an effective and useful numerical simulation scheme for the investigation of the ultra-fast laser pulses in tenuous plasmas. The accuracy of the method is tested by numerical examples. We check some special examples to investigate the laser envelope evolving and modulation in plasmas. Asymmetric two-peak modulation structure is found and its underlying physics is analyzed. The advantages and shortages of the method are also discussed. 相似文献
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WANG Hong-Yu XIE Bai-Song 《理论物理通讯》2006,46(9)
We propose an effective and useful numerical simulation scheme for the investigation of the ultra-fast laser pulses in tenuous plasmas. The accuracy of the method is tested by numerical examples. We check some special examples to investigate the laser envelope evolving and modulation in plasmas. Asymmetric two-peak modulation structure is found and its underlying physics is analyzed. The advantages and shortages of the method are also discussed. 相似文献
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为了降低样品表面对激光束的反射率,提高激光诱导等离子体的辐射强度,文章报道了一种在钢样品表面涂抹碳层的方法.实验结果表明,当一束高能量激光(~25 D作用于覆盖有适当厚度碳涂层的钢样品时,激光等离子体发射的谱线强度提高了10%~28%.为解释谱线强度增强的机理,测量了等离子体的激发温度.此外,实验研究还发现,更强的原子发射光谱出现在激光等离子体径向的1 mm处,而不是在其中心位置. 相似文献
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The numerical solution of the quantum Landau kinetic equation for a dense electron gas is considered. Being one of the most simple kinetic equations, it still retains essential physical features of a correlated many-particle system, such as selfconsistent static screening and Pauli blocking, and, at the same time, it is a good test case for the efficiency of numerical methods. Two schemes for the evaluation of the scattering rates and the collision integral are discussed. To illustrate our results, we present time-dependent calculations i) for the relaxation of a nonequilibrium electron distribution function and ii) for the stopping of fast electrons. 相似文献
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钨合金长杆弹侵彻半无限钢靶的数值模拟及分析 总被引:7,自引:0,他引:7
利用显式动力有限元程序ANSYS/LS=DYNA,采用ALE方法和Steinberg本构模型,对钨合金长杆弹侵彻半无限厚钢靶进行了数值模拟,给出了侵彻过程4个阶段的完整图像和相关物理量的时程变化曲线,分析了弹、靶的压力分布、质点速度以及材料的流动特性。结果表明:在较大速度范围内,模拟计算的侵彻深度与实验结果吻合得很好;沿侵彻轴线,弹靶交界面附近的材料行为主要由静水压力控制。 相似文献
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讨论了利用激光等离子体产生水窗波段X光辐射的可能途径。靶材,即原子序数的选取是决定产生这一波段辐射的基本因素,利用激光等离子体的平衡态和非平衡态特性都可在水窗波段产生亮度X光辐射,提出利用黑体辐射来实现水窗波段X光显微成像研究的方案。 相似文献
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采用爆炸力学、岩石断裂动力学对3种切缝药包进行理论分析表明,复合型切缝药包在切缝方向的剪应力是常规切缝药包的1.59倍左右;采用有限元软件ANSYS10.0/LS-DYNA对其进行数值模拟实验,通过对比3种装药结构的爆炸效果,表明复合型切缝药包在切缝方向的聚能效应最佳;通过对比复合型切缝药包切缝方向和垂直切缝方向的等效塑性应变,得出切缝方向塑性应变峰值是垂直切缝方向的2.93倍左右;通过对比远区围岩压力,得出复合型切缝药包在远区形成的爆炸压力最小,对围岩的损伤程度最小,能量利用最充分。 相似文献
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Numerical Study of Instabiities in Magnetized Inhomogeneous Plasmas under the Effect of Ionization 下载免费PDF全文
J. Chaudhary 《等离子体物理论文集》2016,56(2):113-125
Influence of ionization is studied on two stream instability (TSI) in an inhomogeneous plasma in the presence of obliquely applied magnetic field. In addition to the usual TSI, a new type of instability is found to occur in this system, which is driven by the magnetic field and survives for relatively longer wavelength of oscillations. The growth rates of both the instabilities are enhanced by the magnetic field but their magnitudes attain a minimum value at certain angles of the wave propagation depending upon the wavelength of oscillations. At a critical value of ionization rate there is a sudden fall in the growth of both the instabilities, the reason of which is understood as the Landau damping. A further enhancement in the ionization suppresses the usual TSI whereas the magnetic field‐driven instability attains much lower growth. This new type of instability grows faster in the plasma having heavier ions, but shows a weak dependence on the charge of the ions. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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混合对流热损失是影响太阳能与生物质超临界水气化耦合制氢腔式吸热器热效率的关键因素之一。本文以动力工程多相流实验室建成的生物质超临界水与太阳能聚集供热耦合制氢腔式吸热器为研究对象,对腔式吸热器混合对流换热进行了数值模拟研究。通过使用RNGkε湍流模型,研究了制氢吸热器在外界风吹掠环境下的混合对流热损失,获得了腔式吸热器在不同风速、风向吹掠下的混合对流换热准则Nusselt数。模拟结果表明,侧向风与侧迎向风对腔内对流热损失影响最大,当风速超过某一数值(Richardson数>1),外界风诱发的强制对流会在对流热损失中占主导作用,且随着风速增加,混合对流热损失随Re提高而增大。 相似文献
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为了考核随机过程数值仿真中采用的混沌多项式展开,小波动态自适应网格等的可靠性和近似程度,本文构造了一个具有解析解的随机过程,随后进行数值仿真。比较了数值仿真结果与解析解,证明两者是相互一致的。说明所采用的数值仿真方法是成立和近似度是可以接受的。所进行比较的随机过程解析解是相对比较简单的,当对更复杂的情况需要进一步数值实验验证。在文中并讨论了影响数值仿真精度和增加数值仿真工作难度的因素。 相似文献