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1.
通过改变Z箍缩负载的初始形状和/或质量密度分布,可以实现等离子体的准球形聚心内爆.同柱形箍缩相比,准球形电磁内爆可以将内爆动能集中加载至负载中心较小的空间区域内,获得更高的能量密度,从而在驱动Z箍缩动态黑腔实现聚变点火方面具有潜在优势.准球形电磁内爆的负载和电极结构比柱形Z箍缩更复杂,球面收缩的几何特点使其内爆动力学过程和能量定标关系显著区别于柱形内爆.本文利用解析的薄壳模型推导并分析了理想条件下准球形电磁内爆的动力学行为和能量定标关系,并同二维磁流体力学模拟结果进行了比较.与柱形Z箍缩内爆相比,准球形电磁内爆的动能不仅与驱动电流有关,而且敏感地依赖于负载的初始尺寸.在不显著降低驱动电流和内爆品质的前提下,适当增加负载的初始半径和最大纬度,有利于获得更多的内爆动能和能量加载密度. 相似文献
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Physical model of acoustic forward scattering by cylindrical shell and its experimental validation 下载免费PDF全文
Research on the underwater target scattering can provide
important theoretical support for target detection. The scattering
model of cylindrical shell is established in this paper. It is found
that the forward target strength is much stronger and varies with
angles of incident wave less significantly than backward target
strength. The received forward signal strength fluctuates with the
target moving due to the interference between direct signal and
scattering signal, which is most significant when target approaches
the baseline. An experiment is carried out in an anechoic tank to
validate the scattering model. The method of acquisiting forward
scattering in the tank is proposed. The forward and the backward
target strengths are achieved by using the pulse compression
technology, and they are about 3dB less than the modeling results.
The forward scattering phenomena of quiescent and moving target are
measured, which are similar to modeling results with different
target types. 相似文献
3.
金属丝阵Z箍缩(Z-pinch)内爆是产生强x射线辐射的重要方法之一.在一定脉冲功率加速器条件下,金属丝阵质量和丝阵半径的选择决定了Z-pinch内爆等离子体辐射产额的大小.采用薄壳模型计算了不同丝阵质量、不同丝阵半径、不同粗细和不同材料金属丝构成的丝阵的内爆时间、内爆轨迹、内爆速度,以及最大动能和动能转换率,综合分析了丝间隙、内爆时间、动能转换率与丝阵质量和丝阵半径的关系,给出了在一定负载驱动电流条件下,金属丝阵的最佳参数.分析表明计算结果与实验上观察得到的内爆规律一致.
关键词:
Z-pinch内爆等离子体
金属丝阵负载
薄壳模型 相似文献
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ICF内爆物理研究中,示踪元素X射线谱诊断方法是推测内爆压缩温度、 密度以及燃料混合状态的有效方法.针对其中的非平衡物理过程, 研制了非局域热动平衡(non-LTE)下一维谱线输运程序Alpha.程序以辐射流体计算给出的温度、 密度等量为输入条件,求解细致组态(DCA)模型下的原子动力学方程和辐射输运方程, 自洽给出谱线不透明度,和成像面上的X射线谱分布.利用该程序,模拟了神光Ⅱ装置上的掺Ar靶丸内爆示踪元素X射线谱诊断实验, 研究结果表明,谱线的自吸收效应影响发射的X射线谱的强度和形状, 谱线的宽度对自吸收效应的强弱也有影响.因此,在对X射线谱的数值模拟中应该考虑自吸收效应. 另外,与LTE近似下的发射谱的比较表明, LTE近似下,等离子体电离度大~1, 发射谱的形状与non-LTE的结果不同,且LTE近似下,谱线的强度比non-LTE的谱线强度大5-10倍, 采用LTE近似是不合适的. 相似文献
7.
A three-body force shell model (TSM) for the calculation of Schottky defect formation energies in solids with cesium chloride
structure has been developed by incorporating the effects of long-range three-body interactions (TBI) in the shell model.
These TBI in the defect lattice arise from the deformation of electron shells when the nearest neighbour ions get relaxed
from their equilibrium position. This model has been used to calculate the cation and anion extraction and Schottky defect
formation energies of CsCl, CsBr, CsI, TlCl, TlBr and NH4Cl crystals. The calculated values of these defect properties agree reasonably well with their measured values. 相似文献
8.
Andrej Vincze Jaroslav Bruncko Miroslav Michalka Daniel Figura 《Central European Journal of Physics》2007,5(3):385-397
One of the most important and promising materials from metal oxides is ZnO with specific properties for near UV emission and
absorption optical devices. The properties of ZnO thin films strongly depend on the deposition method. Among them, pulsed
laser deposition (PLD) plays an important role for preparing various kinds of ZnO films, e.g. doped, undoped, monocrystalline,
and polycrystalline. Different approaches — ablation of sintered ZnO pellets or pure metallic Zn as target material are described.
This contribution is comparing properties of ZnO thin films deposited from pure Zn target in oxygen atmosphere and those deposited
from sintered ZnO target. There is a close connection between final thin film properties and PLD conditions. The surface properties
of differently grown ZnO thin films are measured by secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM)
and scanning electron microscopy (SEM). Furthermore, different approaches — ablation of sintered ZnO pellet or pure metallic
Zn as target materials are described. The main results characterize typical properties of ZnO films versus technological parameters
are presented.
Presented at 5-th International Conference Solid State Surfaces and Interfaces, November 19–24, 2006, Smolenice Castle, Slovakia 相似文献
9.
We present an analytical model of transient compressive stress evolution during growth of thin films with high surface and grain boundary diffusivities on substrates. The model provides a closed-form analytical solution which compares well with numerical analysis as well as recent experimental data on transient stress evolution during electrodeposition of Sn films on substrates. 相似文献
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激光目标模拟器是激光制导武器半实物仿真系统的一个重要组成部分。它主要是用来模拟随气象条件、目标反射特性以及飞行距离的变化而变化的激光脉冲,为激光导引头提供一个与实际工作环境相接近的回波信号。从理论上论证了这种激光目标模拟器的可行性。依据波长为1 06μm的激光在大气中的传输特性,结合各种外界条件对它的影响,建立了激光传输的能量链模型,为激光制导武器半实物仿真系统提供了理论依据。 相似文献
12.
A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding-gate MOSFETs 下载免费PDF全文
A two-dimensional analytical subthreshold behavior model for junctionless dual-material cylindrical surrounding- gate (JLDMCSG) metal-oxide-semiconductor field-effect transistors (MOSFETs) is proposed. It is derived by solving the two-dimensional Poisson's equation in two continuous cylindrical regions with any simplifying assumption. Using this analytical model, the subthreshold characteristics of JLDMCSG MOSFETs are investigated in terms of channel electro- static potential, horizontal electric field, and subthreshold current. Compared to junctionless single-material cylindrical surrounding-gate MOSFETs, JLDMCSG MOSFETs can effectively suppress short-channel effects and simultaneously im- prove carrier transport efficiency. It is found that the subthreshold current of JLDMCSG MOSFETs can be significantly reduced by adopting both a thin oxide and thin silicon channel. The accuracy of the analytical model is verified by its good agreement with the three-dimensional numerical simulator ISE TCAD. 相似文献
13.
F. Rahaman M. Kalam K. A. Rahman S. Chakraborti 《General Relativity and Gravitation》2007,39(7):945-956
Recently, Dadhich et al. (Phys. Lett. B 487, 1, 2000) have discovered a black hole solution localized on a three brane in five dimensional gravity in the Randall–Sundrum
scenario. In this article, we develop a new class of thin shell wormhole by surgically grafting above two black hole spacetimes.
Various aspects of this thin wormhole are also analyzed. 相似文献
14.
The observed excited states of 122Ce nucleus have been studied in the framework of projected shell model (PSM). The yrast band has been studied up to spin 26ħ. The first band crossing has been predicted above a rotational frequency of 0.4 MeV/ħ that corresponds to first backbending. The calculation reproduces the experimentally observed ground state band up to spin
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ħ. The electromagnetic quantities, transition quadrupole moments and g-factors are predicted and there is a need to measure these quantities experimentally. 相似文献
15.
研究弹性细杆Kirchhoff模型及其相关演化系统, 是深入考察宏观、微观柔性体拓扑结构与稳定性问题的重要依据. 以DNA弹性细杆数学模型为背景, 考虑截面非对称性特征的影响, 构造新的复数形式Kirchhoff系统. 在此基础上, 结合复变量扭矩设解形式, 获得了非对称截面系统的有效抗弯刚度; 并通过相关理论在高维系统简化过程中的应用, 得到了对应于原有系统的单变量二阶常微分方程. 此外, 将DNA分子具备的抗弯刚度周期变化特征转化为针对有效抗弯刚度的周期摄动形式, 以期从总体上减少理论分析对于数值积分的依赖, 为后续定量分析工作提供新的思路. 相似文献
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研究弹性细杆Kirchhoff模型及其相关演化系统, 是深入考察宏观、微观柔性体拓扑结构与稳定性问题的重要依据. 以DNA弹性细杆数学模型为背景, 考虑截面非对称性特征的影响, 构造新的复数形式Kirchhoff系统. 在此基础上, 结合复变量扭矩设解形式, 获得了非对称截面系统的有效抗弯刚度; 并通过相关理论在高维系统简化过程中的应用, 得到了对应于原有系统的单变量二阶常微分方程. 此外, 将DNA分子具备的抗弯刚度周期变化特征转化为针对有效抗弯刚度的周期摄动形式, 以期从总体上减少理论分析对于数值积分 相似文献
18.
A new analytical model of high voltage silicon on insulator (SOI) thin film devices 总被引:2,自引:0,他引:2 下载免费PDF全文
A new analytical model of high voltage silicon on insulator (SOI)
thin film devices is proposed, and a formula of silicon critical
electric field is derived as a function of silicon film thickness by
solving a 2D Poisson equation from an effective ionization rate,
with a threshold energy taken into account for electron multiplying.
Unlike a conventional silicon critical electric field that is
constant and independent of silicon film thickness, the proposed
silicon critical electric field increases sharply with silicon film
thickness decreasing especially in the case of thin films, and can
come to 141V/μm at a film thickness of 0.1μm which is
much larger than the normal value of about 30V/μm. From the
proposed formula of silicon critical electric field, the expressions
of dielectric layer electric field and vertical breakdown voltage
(VB,V) are obtained. Based on the model, an ultra thin film
can be used to enhance dielectric layer electric field and so
increase vertical breakdown voltage for SOI devices because of its
high silicon critical electric field, and with a dielectric layer
thickness of 2μm the vertical breakdown voltages reach 852
and 300V for the silicon film thicknesses of 0.1 and 5μm,
respectively. In addition, a relation between dielectric layer
thickness and silicon film thickness is obtained, indicating a
minimum vertical breakdown voltage that should be avoided when an
SOI device is designed. 2D simulated results and some experimental
results are in good agreement with analytical results. 相似文献
19.
Current patch test for Mindlin plate element only satisfies the zero shear deformation condition. The patch test of non-zero
constant shear for Mindlin plate problem cannot be performed. For shell element, the patch test does not even exist. Based
on the theory of enhanced patch test proposed by Chen W J (2006), the authors proposed the enhanced patch test function for
Mindlin plate and thin cylindrical shell elements. This enhanced patch test function can be used to assess the convergence
of the Mindlin plate and cylindrical thin shell elements.
Supported by the National Natural Science Foundation of China (Grant Nos. 50479058 and 10672032) 相似文献