共查询到18条相似文献,搜索用时 280 毫秒
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采用Monte Carlo方法模拟强流脉冲离子束与铝基钛膜双层靶的相互作用.强流脉冲离子束与双层靶材相互作用过程中,随着离子的注入,高能离子束引起涂层原子与基体材料原子之间相互渗透和混合,同时离子能量沉积到靶材内一定深度,并呈规律性的空间分布.这种能量分布影响靶内两种材料的熔化或气化过程,并导致界面物质结合强度发生变化.利用建立的束流模型,计算束流在靶材内的能量沉积和分布状况及界面处级联碰撞对双层靶界面混合区的影响,得出强流脉冲离子束混合双层靶时级联碰撞不起主要作用的结论,离子流密度在100A·cm-2~150A·cm-2时对离子束混合最为有利. 相似文献
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利用拟合实测的TEMP Ⅱ型加速器磁绝缘二极管(MID)电压波形及其焦点附近束流密度曲线,建立了Gaussian分布模型,据此计算了与靶作用的离子的能量及数量,采用Monte Carlo(MC)方法计算了沉积在靶内的能量.并以此作为热源,与流体动力学(HD)模型相结合,对不同的靶状态采用相应的状态方程,模拟计算了靶内压力演化情况; 同时对烧蚀产生的等离子体采用理想气体状态方程, 结合HD方程组, 模拟计算了喷发过程中压力的空间演化过程.
关键词:
强流脉冲离子束
Gaussian模型
HD方程
数值研究 相似文献
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利用Monte Carlo(MC)模型研究了能量粒子对薄膜生长的初始阶段岛膜的形貌和岛的尺寸的影响,沉积粒子的能量范围为:0—0.7eV.在模型中考虑了原子沉积、吸附原子扩散和蒸发等过程,并详细考虑了临近和次临近原子的影响.结果表明,在所采用的参量范围内不同的基底温度情况下,能量粒子的影响有很大的区别.低基底温度情况下,沉积粒子强烈地影响着薄膜的生长过程中,岛膜的形貌、数量和尺寸随能量粒子的能量增加而有很大的变化.分析表明,这些变化都是由于能量粒子的介入使得表面吸附粒子的扩散能力增强所致
关键词:
薄膜生长
Monte Carlo方法
扩散 相似文献
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冯贤平 《原子与分子物理学报》2005,22(1):30-33
本文的基本思想是设计双层金铝薄膜靶以检测激光脉冲宽度与等离子体消融深度的关系,找出有效的等离子体加热方法以产生更强更亮的等离子体辐射源.由于有预脉冲激光的存在,表层金薄膜首先被消融,由主脉冲携带的大能量就能较易穿过表层金等离子体将能量聚焦在内层铝靶上,由此产生内层高温等离子体.又由于外层低温等离子体存在,其将有效的阻碍内高温等离子体因膨胀而引起的能量损失.对无预脉冲而言,直接入射激光能量都沉积在靶表层形成表层高温等离子体.但是激光直接入射而产生的等离子体辐射总强度只比由预脉冲情况下产生的金等离子体辐射强度增加15%.而预脉冲能量只占激光总能量的2%.实验结果显示Al光谱线主要来自类氢,类氦离子跃迁.Au等离子体光谱线主要来自它的N带,O带和P带谱.我们也观察到一个明显的软X射线短波发射极限.所有结果显示由于预脉冲的存在将对靶各层等离子体辐射产生极大的影响 相似文献
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在回顾和总结现有强脉冲离子束诊断技术和能量沉积模型的基础上, 结合红外成像诊断分析, 基于能量平衡, 提出了强脉冲离子束在固体靶中功率密度分布模型, 并采用蒙特卡罗方法对其进行计算. 以该功率密度模型作为源项, 使用有限元分析方法模拟强脉冲离子束入射100 μm不锈钢靶后内部温度场在毫秒时间范围内的分布和演化. 结果显示, 在微秒时间范围内, 热场以存在于近表面区域数倍于离子射程范围内的冲击热场为主要特征; 而在毫秒时间范围内, 靶的前后表面(纵向)已达到温度平衡, 且靶后表面温度场和入射前表面的离子束横截面能量密度具有空间分布的相似性. 这证明了, 在采用具有毫秒响应速度的红外拍摄系统的情况下, 背面红外诊断技术可以实现以较高的精度对强脉冲离子束横截面的能量分布进行诊断和分析. 相似文献
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《物理学报》2020,(11)
高能量密度纳秒量级强脉冲离子束辐照材料表面的烧蚀产物和束流的相互作用,可能对束流在靶中的能量沉积产生影响,进而影响烧蚀情况下的束流分析和相关应用的优化.本文采用红外成像方法对横截面能量密度1.5—1.8 J/cm~2的强脉冲离子束在304不锈钢和高分子材料上的能量沉积进行了测量分析.结果表明在高分子材料上,在超过一定能量密度后,束流引发材料表面烧蚀产物的屏蔽效应使得大部分束流能量不能沉积在靶上.采用有限元方法对束流引发的温度场分布进行了计算,验证了高分子材料的低热导率以及低分解温度使其在脉冲辐照早期即开始热解,烧蚀产物对后续束流能量的进一步沉积产生屏蔽.此类效应在金属上存在的可能性和对束流诊断等应用的影响,亦进行了讨论. 相似文献
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基于硼转换的GEM(Gas Electron Multiplier)探测器性能突出,计数率高达10 MHz以上,耐辐射,信号读出方式简单、灵活,位置与时间分辨率高,是下一代中子束流监测器极具优势的候选者。这种新型中子束流监测器主要由硼中子转换层、气体电离粒子放大的GEM以及二维读出电极组成。通过Geant4程序包对探测器物理过程进行蒙特卡罗(Monte Carlo)模拟,主要研究了硼中子转换层转换效率与厚度及中子波长的关系、出射粒子的能谱、不同气体比分不同气体厚度中的能量沉积、以及γ的能量沉积,计算比较了不同厚度GEM膜对快中子产生的影响。模拟结果表明,出射粒子在漂移区的能量沉积几乎与气体比分无关,硼层厚度取0.1μm以下,漂移区厚度6 mm时,可以确保出射粒子在漂移区能量完全沉积,同时具有最佳n/γ区分能力。 相似文献
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Two-dimensional numerical research on effects of titanium target bombarded by TEMPⅡ accelerator
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Two-dimensional numerical research has been carried out on the ablation effects of
titanium target irradiated by intense pulsed ion beam (IPIB) generated by TEMP II
accelerator. Temporal and spatial evolution of the ablation process of the target
during a pulse time has been simulated. We have come to the conclusion that the
melting and evaporating process begin from the surface and the target is ablated
layer by layer when the target is irradiated by the IPIB. Meanwhile, we also
obtained the result that the average ablation velocity in target central region is
about 10\,m/s, which is far less than the ejection velocity of the plume plasma
formed by irradiation. Different effects have been compared to the different ratio
of the ions and different energy density of IPIB while the target is irradiated by
pulsed beams. 相似文献
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V. P. Afanas’ev P. S. Kaplya I. A. Kostanovskiy 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2013,7(1):123-129
The energy spectra of electrons reflected from a gold layer deposited onto a silicon substrate have been measured when the energy losses are comparable with the energy of a probe electron beam (5 keV) and the elastic energy losses correspond to an electron-beam energy of 14 keV. A subsequent theory for calculating the energy spectra of electrons and light ions reflected from a multilayer target, which is used to interpret the energy spectra measured in the wide range of energy losses, has been developed. It is found that the elastic scattering processes in the gold layer (the thickness of which is tens of monolayers) substantially affect formation of the energy spectra. The Au layer thicknesses calculated by means of the developed theory are compared with those determined from the spectra of elastically reflected electrons. The errors of the Au layer thickness measurements via the proposed method are discussed. 相似文献
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Laser induced reverse transfer (LIRT) has been executed first time using a Mega Hertz pulse frequency femtosecond laser radiation under ambient conditions. Research has been conducted to understand the evolution of deposited structures with regard to pulse energy. Solid deposition of gold could be deposited on quartz substrate only if pulse energy falls within a certain range. For the experiment conducted in this work, it is 36-40 nJ. For energies above this range, crests appear in the middle of the deposition. There is a threshold in maximum applicable pulse energy, 82 nJ in this exepriment, beyond which further increase in pulse energy results in only traces of deposited material. Results also show that the width of deposited line increases with the increase in pulse energy and decreases with the increase in scan speed. These observations have been explained using the dynamics of ablated plume. 相似文献
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The liquid–gas phase transition in hot neutron-rich nuclear matter is investigated within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, a momentum-independent interaction (MID), and an isoscalar momentum-dependent interaction (eMDYI). The boundary of the phase-coexistence region is shown to be sensitive to the density dependence of the nuclear symmetry energy with a softer symmetry energy giving a higher critical pressure and a larger area of phase-coexistence region. Compared with the momentum-independent MID interaction, the isospin and momentum-dependent MDI interaction is found to increase the critical pressure and enlarge the area of phase-coexistence region. For the isoscalar momentum-dependent eMDYI interaction, a limiting pressure above which the liquid–gas phase transition cannot take place has been found and it is shown to be sensitive to the stiffness of the symmetry energy. 相似文献
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对强流脉冲离子束(IPIB)辐照Ti靶的烧蚀效应进行了二维数值研究.得到了表面烧蚀物质随脉冲时间的变化关系.得出TEMP Ⅱ 型加速器产生的脉冲束流辐照靶材时引起的汽、液化均是从表面开始、并且汽化过程中表面物质被层层烧蚀的结论.同时,得到中心区的平均烧蚀速度为10m/s 数量级,它远小于产生的烧蚀等离子体的喷发速度.得到脉冲期间靶材内部不同位置烧蚀斑痕形状的时间演化过程,以及束流中含有的离子种类分额不同时IPIB辐照过程产生的不同效果.
关键词:
强流脉冲离子束
靶
烧蚀过程
二维数值模拟 相似文献
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Taking the calculation results based on the established two-dimensional ablation model of the intense-pulsed-ionbeam (IPIB) irradiation process as initial conditions, we build a two-dimensional hydrodynamic ejection model of plasma produced by an IPIB-irradiated metal titanium target into ambient gas. We obtain the conclusions that shock waves generate when the background pressure is around 133 mTorr and also obtain the plume splitting phenomenon that has been observed in the experiments. 相似文献