共查询到20条相似文献,搜索用时 15 毫秒
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本文测量了200~550 keV的Xe10+离子轰击高纯度(9999%)Al表面诱发的溅射Al原子的光发射,研究了Al Ⅰ
30810、30914、39452、39628
nm光谱线强度比值和光子产额随入射离子能量的变化趋势。在本实验能量范围内,辐射光谱线强度比值随入射离子能量增加几乎不变,而发射谱线的光子产额随入射离子能量的增加呈现出不同趋势:入射离子能量为450
keV时,光子产额出现极大值,入射离子能量超过450
keV时,光子产额随能量的增加而减少,其变化趋势与核阻止本领随能量增加的变化没有出现类同的变化特征。结合核阻止和电子阻止效应对实验结果进行了讨论,结果表明:入射离子能量低于450
keV时,核阻止在碰撞中起主导作用,入射离子能量高于450 keV时,电子阻止在碰撞中起主导作用。 相似文献
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Ijaz Shahid Jie Shen Xiao Yu Haowen Zhong Xiaojun Cui Guoying Liang Wanying Huang Shijian Zhang Sha Yan Xiaofu Zhang Xiaoyun Le 《Journal of Fusion Energy》2018,37(5):261-269
Due to the outstanding physical properties, Tungsten has been proposed for use in the divertor of future fusion devices. However, tungsten shall face strong particle bombardment from the plasma, which causes severe damage to the material. The purpose of this work is to build such an accurate analytical model which can predict the damages in target material like crack production and propagation after high intense pulsed ion beam irradiation. Hence, a two-dimensional finite element method is used to study the effect of high intense pulsed ion beam on tungsten surface numerically. To judge temperature and stress distribution in material, thermal conduction model is combined with non-linear fracture mechanics model and J-Integral parameter is used as a criterion to judge the crack propagation. Simulation results reveal that different crack heights and sizes can affect the results and there is a critical depth for crack propagation. The model gives good results to real experimental observations and has potential applications for different intense pulsed electron/plasma beams and different target materials as well. 相似文献
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Effect of both electron beam irradiation on the properties of polypropylene (PP) films the irradiation on the different layers of a multilayer PP film are studied. A Fourier transform infrared spectroscope was used to investigate the chemical structure of the films. The results showed that the chemical properties of the first layer were improved, that is, more functional groups responsible for dye ability and hydrophilicity of the film were produced on its surface, while noticeable improvement was not detected on the surface of other layers. This was also confirmed by testing the dye ability of the layers. However, the results obtained by atomic force microscopy showed that the electron irradiation caused some topographical changes, not only on the surface of the first layer but also on the others. 相似文献
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采用500 keV的He离子在750 ℃下对GH3535合金样品进行辐照,然后利用掠入射X射线衍射(GIXRD)、透射电子显微镜(TEM)和纳米压痕仪分别对样品的氦泡和位错环辐照缺陷的演化及纳米硬度的变化进行了研究。结果表明,GH3535合金晶格辐照后发生了轻微畸变;离子辐照在样品中形成了大量尺寸为2~5 nm的氦泡和位错环。辐照产生的氦泡和位错环等缺陷在基体中钉扎位错,从而使材料产生了辐照硬化现象,样品硬度随辐照剂量的增加而增大。当辐照剂量达2×1016 cm-2时,辐照样品发生了明显的硬化饱和现象,利用Nix Gao模型计算得此时的硬化程度为64%。 相似文献
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在高放射性废物深地质处置过程中,放射性核素衰变引起的强辐射场会导致玻璃固化体浸出性能的变化。本工作利用15 MeV Si离子辐照模拟深地质处置强辐射场,采用MCC-1静态浸泡法在pH=9.0的KOH溶液中对硼硅酸盐玻璃分别浸泡1、3、7、14、28 d,结合电感耦合等离子体发射光谱仪、拉曼光谱仪以及扫描电镜研究了辐照前后玻璃样品的浸出行为。结果表明:随着浸出时间推移,玻璃表面会不断地腐蚀脱落;辐照后玻璃样品的浸出率明显高于未辐照玻璃样品的,蚀变层结构与元素组成无明显差异,但厚度明显增大;形成的蚀变层中Na元素和B元素基本耗尽;蚀变层中SiO_(2)网络体结构溶解,生成大量的Si—OH键及硼硅酸盐结构,并出现四配位B单元向三配位B单元的转变。 相似文献
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针对一台功率为15kW的1.5 MeV电子辐照平台,进行了屏蔽计算分析与改造设计工作。根据辐照平台厂房布局建立三维模型,使用蒙特卡罗方法进行了相应屏蔽计算。通过对辐照平台主屏蔽体外光子剂量率的计算,对已有建筑物墙体的屏蔽效果进行评估。评估结果表明,建筑物四周墙体厚度满足设计要求。对辐照室和门洞等局部位置进行了屏蔽计算设计,通过对不同屏蔽厚度的计算结果进行比较,给出了满足设计要求的合理可行的设计方案。为验证屏蔽计算结果,在工程验收阶段,对周围人员活动区域进行了现场测量。测量结果表明,辐照平台原有主体屏蔽及新增局部屏蔽可使光子剂量率低于设计目标值,满足防护要求。 相似文献
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S. Coffa G. Franz F. Priolo S. Libertino R. Mosca E. Gombia C. Spinella 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1996,120(1-4):74-80
We show that the major problems hampering efficient performances of Si in optoelectronic applications, i.e. the achievement of efficient light emission and fast modulation, can be successfully approached by a proper engineering of its optical properties. In particular, the incorporation of a high Er concentration, if concomitant with codoping with other impurities such as O and F, allows to achieve efficient 1.54 μm light emission at room temperature. This emission arises from an electrically excitable, atomically sharp, intra 4f transition of the Er ions. The formation of impurity-rare earth ion complexes is shown to enhance the effective solubility of Er in Si and optimize its electrical properties thus providing a higher excitation efficiency and a reduction of the temperature quenching of the luminescence yield. Furthermore we show that the proper design of a Si light emitting diode, allowing the incorporation of Er ions within the depletion layer region of a p+-n+ junction, allows to achieve simultaneously high efficiency and fast modulation of the electroluminescence signal. In fact, under reverse bias, Er ions are pumped with a cross section of 6 × 10−17 cm2 and decay with a lifetime of 100 μs, which guarantees an internal quantum efficiency > 10−4 and an emitted power of 30 μW at room temperature. On the other hand, at the diode turn-off, the onset of fast, non-radiative, Auger-type decay processes of the excited ions allow a very fast turn off of the electroluminescence signal. 相似文献
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利用中国科学院近代物理研究所320 kV高压平台提供的氦离子辐照烧结碳化硅,辐照温度从室温到1 000 ℃,辐照注量为1015~1017 cm-2。辐照完成后,进行退火处理,然后开展透射电子显微镜、拉曼光谱、纳米硬度和热导率测试。研究发现,烧结碳化硅中氦泡形核阈值注量低于单晶碳化硅。同时,氦泡形貌和尺寸与辐照温度、退火温度有关。另外,对辐照产生的晶格缺陷、元素偏析进行了研究。结果表明,辐照产生了大量的缺陷团簇,同时氦泡生长也会发射间隙子,在氦泡周围形成间隙型位错环。在晶界处,容易发生碳原子聚集。辐照导致材料先发生硬化而后发生软化,且热导率降低。 相似文献
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紫外辐照对溶胶-凝胶光学薄膜性能的影响 总被引:4,自引:0,他引:4
采用溶胶-凝胶技术,使用旋涂方法在K9玻璃和单晶硅片上制备各种光学薄膜,并用紫外光源作为高能光子源辐照溶胶-凝胶光学薄膜。使用扫描电镜(SEM)、原子力显微镜(AFM)、椭偏仪、铅笔硬度仪等测量和分析薄膜的特性。用输出波长1 064 nm、脉宽15 ns电光调Q激光系统测试薄膜的激光损伤阈值。结果表明,紫外光辐照可提高薄膜折射率和机械性能。采用紫外预处理还能将节瘤缺陷转换成孔洞缺陷,从而有效提高薄膜的激光损伤阈值,其中,单层ZrO2薄膜的激光损伤阈值达到50.6 J/cm2(1 064 nm,1 ns)。与当前流行的激光预处理技术相比,紫外预处理的设备简单、易于操作。溶胶-凝胶多层膜经紫外光处理后,有效提高了多层膜膜层的均匀性。 相似文献
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J. Gyulai 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1217-1221
A review is given on the start and early years of the biannual conferences ‘Ion Beam Modification of Materials’ (IBMM), on the thirtieth anniversary of the meeting held in Budapest, 1978. Organizers of this first IBMM conference decided to broaden the scope of the previous few conferences on ion implantation to embrace side effects, like ion beam mixing, etc. also by giving a new name. The start was not free from influence of politics of the times. The scientific success, however, gave enough ammunition for the coming times to IBMM, mainly through continuous support of leading scientists of the field. Thus, it became the most important forum of studies of basics of ion beam processes. Numerous references illustrate the start and the early topics dealt with at the meetings. 相似文献
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K. Volz J. K. N. Lindner B. Stritzker 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1996,120(1-4):133-138
Epitaxial, buried silicon carbide (SiC) layers have been fabricated in (100) and (111) silicon by ion beam synthesis (IBS). In order to study the ion beam induced epitaxial crystallization (IBIEC) of buried SiC layers, the resulting Si/SiC/Si layer systems were amorphized using 2 MeV Si2+ ion irradiation at 300 K. An unexpected high critical dose for the amorphization of the buried layers is observed. Buried, amorphous SiC layers were irradiated with 800 keV Si+ ions at 320 and 600°C, respectively, in order to achieve ion beam induced epitaxial crystallisation. It is demonstrated that IBIEC works well on buried layers and results in epitaxial recrystallization at considerably lower target temperatures than necessary for thermal annealing. The IBIEC process starts from both SiC/Si interfaces and may be accompanied by heterogenous nucleation of poly-SiC as well as interfacial layer-by-layer amorphization, depending on irradiation conditions. The structure of the recrystallized regions in dependence of dose, dose rate, temperature and crystal orientation is presented by means of TEM investigations. 相似文献
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Johsei Nagakawa 《Journal of Nuclear Materials》1983,116(1):10-16
In the course of irradiation creep experiments on Ni-4 at.% Si alloy, two types of creep transients were observed on the termination of irradiation. The short term transient was completed within one minute while the long term transient persisted for nearly ten hours. A change in the temperature distribution was excluded from the possible causes, partly because the stress dependence of the observed transient strains was not linear, and partly because the strain increase expected from the temperature change was much smaller than the observed value. Transient behavior of point defects was examined in conjunction with the climb-glide mechanism and the steady-state irradiation creep data. Calculated creep transient due to excess vacancy flux to dislocations was in good agreement with the observed short term transient. The long term transient appears to be a result of dislocation microstructure change. The present results suggest an enhanced irradiation creep under cyclic irradiation conditions which will be encountered in the early generations of fusion reactors. 相似文献
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Monika Koster Herbert M. Urbassek 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2001,180(1-4):299-305
By molecular dynamics simulation, we study the response of an initially defect-free a-Si sample to 100 eV Si atom bombardment for fluences up to 2.6×1015 cm−2, i.e., an equivalent of 4 ML coverage. Defects (over-coordinated atoms) are introduced into the sample at depths extending up to 30 Å, far beyond the average projectile range of 5.5 Å. This build-up of over-coordinated atoms is accompanied by a local increase of pressure of more than 1 GPa. For comparison, we also study atom bombardment of a strongly under-dense a-Si sample, prepared by simulated growth. This sample compactifies under irradiation, the initially high bulk concentration of under-coordinated atoms is reduced, and the initially tensile pressure in the sample relaxes. 相似文献
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Recently a model was proposed to account for anomalous infrared attenuation noted experimentally for fast-neutron-irradiated, compound semiconductors. The model represents neutron damage by localized phase transitions to a high-pressure metallic-like state. It is shown that this model not only accounts for the anomalous, continuous optical attenuation at photon energies less than the band gap, but also can explain the absorption edge fuzziness noted for neutron-irradiated GaAs. The optical attenuation produced by embedded metallic zones at frequencies above the absorption edge is derived, and it is shown that the metallic resonance absorption band is altered from the usual Lorentzian shape. It is shown that in GaAs irradiated with fast neutrons at sufficiently high doses the resonant absorption by the metallic phase can dominate the host semiconductor absorption. 相似文献