连续碳纤维增强碳化硅的辐照效应

连续碳纤维增强碳化硅材料除了具有碳化硅材料固有的低中子活化性能,低衰变热性能和低氚渗透性能等优点以外,还具有密度低、线性膨胀系数小、高比强度、高比模量、耐高温、抗氧化、抗蠕变、抗热震、耐化学腐蚀、耐盐雾、优良的电磁波吸收特性等一系列优异性能,是各类核工程重要的潜在候选材料。在核聚变工程应用领域,连续碳纤维增强碳化硅材料作为第一壁材料不可避免地会受到各种辐射粒子的影响。研究清楚这些辐射粒子对它的辐照效应对其在核工程领域的安全使用至关重要。采用蒙特卡罗方法与分子动力学方法进行模拟计算,研究了氕、氘、氚和氦四种粒子对连续碳纤维增强碳化硅的辐照效应。SRIM和LAMMPS计算结果表明:当入射原子能量为100 eV,连续碳纤维增强碳化硅中碳的浓度在80%~85%时,氕、氘、氚和氦原子的溅射率存在最小值;入射粒子的种类对溅射率的影响显著,氦原子的溅射率大于氘原子和氚原子,而氘原子和氚原子的溅射率相差不大但均显著大于氕原子;溅射率随入射能量的增加先迅速增加后逐渐减小,氕、氘、氚和氦原子入射能量分别在200,400,600和800 eV时存在溅射率最大值;当氦原子入射能量为100 eV时,溅射率随入射角度的增加而逐渐减少。这些结果对连续碳纤维增强碳化硅材料在核工程上的应用具有一定的参考意义。Continuous carbon fiber reinforced silicon carbide material has the low neutron activation, low decay heat performance and tritium permeability, which are inherent performance of silicon carbide materials. It also has other advantages such as low density, small linear expansion coefficient, specific strength and specific modulus, high temperature resistance, oxidation resistance, creep resistance, thermal shock, resistance to chemical corrosion, salt fog resistance, excellent electromagnetic wave absorption properties, etc. It is an important potential candidate material in various field of nuclear engineering. In the field of nuclear fusion engineering applications, continuous carbon fiber reinforced silicon carbide as the first wall material will inevitably be bombarded by a variety of radiation particles. The radiation effect is critical to its safe use in nuclear engineering. The Monte Carlo method and the molecular dynamics method were used to study the radiation effect of protium, deuterium, tritium and helium on continuous carbon fiber reinforced silicon carbide. The SRIM and LAMMPS simulation results show that when the incident energy is 100 eV and the concentration of carbon in the continuous carbon fiber reinforced silicon carbide is about 80% ~ 85%, the sputtering yield of protium, deuterium, tritium and helium atoms have the minimum values. The kind of incident particle has a significant effect on the sputtering yield. The sputtering yield of helium atoms is larger than that of tritium atoms and deuterium atoms. There is not much difference between the sputtering yield of deuterium atoms and tritium atoms, and both the sputtering yield of deuterium atoms and tritium atoms are larger than that of protium atoms. The sputtering yield initially increases rapidly with the increase of the incident energy and then decreases gradually. The incident energy of the protium, deuterium, tritium and helium atoms has the maximum value of the sputtering yield at 200, 400, 600 and 800 eV, respectively. When the incident energy of helium atoms is 100 eV, the sputtering yield decreases while the increase of the incident angle. These results can provide a certain reference for the application of continuous carbon fiber reinforced silicon carbide materials in nuclear engineering.     

Effect of Sputtering Parameters on Film Composition,Crystal Structure,and Coercivity of SmCo Based Films Deposited on Si （100） Substrates

The sputtering parameter mediated composition （SPMC） effect of 3.0-μm-thick SmCo-based films is experimentally and theoretically studied. The experimental results give a clear indication that the Sm concentration increases with the decreasing sputtering power or with the increasing Ar gas pressure, which are in agreement with the calculated values when the preferential sputtering effect is disregarded. The SPMC effect provides an opportunity for the same composite target to fabricate films with an Sm concentration varying from 13.8at.% to 17.3at.%, which is reasonable for the magnetic phase transformation （Sm2Co17→SmCo7→SmCo5） and the enhanced coercivity.     

Phenomena of optic-bound effect on fibre optic gyro

The optic-bound effect on fibre optic gyro (FOG) precision is analysed theoretically, and formulas describing the change of FOG light power under the action of optic-bound effect are given. It is confirmed that optic-bound effect is a main instantaneous non-reciprocity effect of FOG in addition to the Sagnac effect and can lead to a dynamic error of FOG in practical environments. An approach to suppressing or eliminating the error due to the optic-bound effect is presented and verified experimentally. The result shows that the approach is valid and the precision of FOG is improved observably.     

Experimentally distinguishing electro-optic effects in silicon

Different electro-optic effects, such as Kerr effect, Pockels effect induced by the electric field or strain, and plasma dispersion effect exist in silicon. Experimentally distinguishing these effects is necessary for designing silicon-based electro-optic devices. According to their different polarization dependencies and frequency responses, these effects are measured and distinguished successfully via a transverse electro-optic modulation experiment based on the near-intrinsic silicon sample. The results indicate that Pockels effect induced by the electric field or strain is primary among these effects in the near-intrinsic silicon sample.     

直流磁控溅射沉积含He钛膜的研究

研究了用He/Ar混合溅射气体的直流磁控溅射制备钛膜中，He的掺入现象.分析结果表明，大量的He原子（He/Ti原子比高达56%）被均匀地引入到Ti膜中，其He含量可由混合溅射气体的He分量精确控制.通过调节溅射参数，可实现样品中He的低损伤引入.研究还发现，溅射沉积的含氦Ti膜具有较高的He成泡剂量和高的固He能力，这可能是溅射沉积形成了纳米晶Ti膜所致.纳米晶Ti膜较粗晶材料具有很高浓度的He捕陷中心，使He泡密度增大而泡尺寸减小.随He引入量的增加，Ti膜的晶粒尺寸减小，He引起的晶体点阵参数和X射线衍射峰宽度增大，晶体的无序程度增加.Helium trapping in the Ti films deposited by DC magnetron sputtering with a He/Ar mixture was studied. He atoms with a surprisingly high concentration (He/Ti atomic ratio is as high as 56%)incorporate evenly in deposited film. The trapped amount of He can be controlled by the helium partial amount. The introduction of the helium with no extra damage(or very low damage) can be realized by choosing suitable deposition conditions. It was also found that because of the formation of nanophase Ti film a relative high He flux for bubble formation is needed and the amount of the retain He in sputtering Ti films is much higher than that in the coarse grain Ti films. The nanophase Ti film can accommodate larger concentration of trapped sites to He, which results in a high density and small size of the He bubbles. With the increasing He irradiation flux, the grain size of Ti film decreases and the lattice spacing and width of the X ray diffraction peak increase due to the He introduction, and the film tends to amorphous phase.     

Phase Structural Characteristics of ZrV2 Thin Film Prepared by Magnetron Sputtering

The thin film metal hydride has become an emerging field of research in metal hydride batteries for its good mechanical and hydrogenation properties. ZrV2 thin films have been prepared using a dc magnetron sputtering method, and the phase structure is investigated. Only amorphous or crystalline Zr and V mixture phases are achieved when substrates are heated during either to 400℃ or to 550℃. The annealing causes segregation of Zr and V in the film induced by strain-driven diffusion and interdiffusion between substrate Mo and film elements at high temperature, which results in the formation of mixture phases ofC14, C15, Zr and V, but the content of C15 phase is not higher compared with that in the bulk material.     

Mo/Si aperiodic multilayer broadband reflective mirror for 12.5-28.5-nm wavelength range

Aperiodic molybdenum/silicon (Mo/Si) multilayer designed as a broadband reflective mirror with mean reflectivity of 10% over a wide wavelength range of 12.5-28.5 nm at incidence angle of 5° is developed using a numerical optimized method. The multilayer is prepared using direct current magnetron sputtering technology. The reflectivity is measured using synchrotron radiation. The measured mean reflectivity is 7.0% in the design wavelength range of 12.5-28.5 nm. This multilayer broadband reflective mirror can be used in extreme ultraviolet measurements and will greatly simplify the experimental arrangements.     

Improving Recording Density of All-Optical Magnetic Storage by Using High-Pass Angular Spectrum Filters

A new design is presented to improve the magnetic recording density in all-optical magnetic storage. By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy. Magnetization of the film is induced by the inverse Faraday effect. As the obstructed angle of the filter increases the magnetic recording density increases evidently. The magnetization intensity and the sidelobe effect are also discussed.     

Analyzing Affect of Image Charge in Space Charge Effect

There is an increasing requirement of high injection current and highly charged ion beams for accelerators at many laboratories, such as CERN, GSI, GANIL and IMP, with the development of super-conducting ECR source in recent.years. In this case, the space charge effect becomes a major concern when the beam current is as high as tens of mA. In fact, the faradic field induced by the image charges will be come into the metallic surfaces while the beams are transported in a vacuum tube or in between two plates. In order to ensure studying the space charge effect in reason, it is necessary to investigate the effect from such a field.     

Recovery of single event upset in advanced complementary metal-oxide semiconductor static random access memory cells

Using computer-aided design three-dimensional (3D) simulation technology,the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied.It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings.It cannot exhibit the recovery effect.It is also indicated that the upset linear energy transfer (LET) threshold is kept constant while the recovery LET threshold increases as the spacing increases.Additionally,the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect,thus strengthening the recovery ability.     

Effect of sputtering anisotropic ejection on the optical properties and residual stress of Nb2O5 thin films

The effect of sputtering anisotropic ejection on the optical properties and internal stress of niobium pentoxide (Nb₂O₅) films prepared by ion-beam sputtering deposition (IBSD) was investigated experimentally. Thin films were deposited on unheated BK7 glass substrates and silicon wafers at different ejection angles surrounding a metal target. The ejection angles varied from 0° to 75° in increments of 15° for each substrate. It was found that the optical constants of the Nb₂O₅ films were significantly influenced by the sputtering ejection angle. The surface roughness and residual stress in the Nb₂O₅ thin films were also found to vary with the ejection angle. In this work, Nb₂O₅ films had a higher refractive index, lower absorption, lower stress and lower roughness when films deposited at an ejection angle of 30°.     

Determination of angle dependence of sputtering yield for a multicomponent target by the time characteristics of the sputtering process

A method for determining the variations of sputtering yield of multicomponent target based on studies of time characteristics of the sputtered particles flux has been proposed and tested on an example of the angle dependence of sputtering yield. Time dependences of variation in the fluxes of the sputtered atoms of multicomponent oxides at different incidence angles of Ar ions were studied. Angular dependences of the sputtering yield for these compounds were obtained by direct measurements and computations. It has been shown that the angular dependence of the sputtering yield in a stationary mode can be obtained from the time dependences of the fluxes of the sputtered particles.     

Analytical calculation of atom ejection from the Ni (111), Ni (001), and Au (001) surfaces in frames of a three-dimensional model

Atom ejection from lattice sites at the Ni (111) and Ni (001) surfaces in the azimuthal direction toward the center of a lens consisting of two nearest neighboring atoms in the surface plane is calculated using a developed analytical three-dimensional model. The types of scattering of ejected atoms are classified in frames of the constructed model. It is found that the first and second ejection cones are observed in the sputtering pattern in the case of atom ejection from the Ni (111) surface and that the contribution of strongly blocked atoms to sputtering is considerable. The focusing of sputtered atoms at some angle from the surface normal is observed. A maximum of the polar angular distribution of sputtered atoms is shifted nonmonotonically as the energy increases. It is shown that the energy spent by the ejected atom on the recoiling of the lens atoms can be larger than that spent by this atom to overcome the potential barrier. It is found that small changes in the potential hardness and the binding energy at the magnetic phase transition can lead to a qualitative change in the ejection pattern. The expressions for the final ejection angle and energy in the case of Ni in the f-state are found in the form of an expansion in terms of two small parameters. As one passes from the case of atom ejection from the Ni (001) face to the case of atom ejection from the Au (001) face, the interaction cross section increases significantly because of an increase in the atomic number and the effects of blocking and focusing turn out to be considerable.     

Emission Theory of Amorphous Material Sputtering: the Dependence of the Sputtering Coefficient on the Angle of Primary Ion Beam Incidence

The dependences of the sputtering coefficient on the types of accelerated ions, their energy, and the angle of incidence on a target are calculated. For Ar–Si, Хе–С, and H–W systems, acceptable coincidence between the calculated and experimental data is obtained. Two mechanisms for secondary-particle ejection from solids are established; they determine the dependences of the base sputtering coefficient for the base on the energy and the angle of primary ion incidence on the target.     

Incident angle dependence of electronic desorption and sputtering by energetic ions

It is shown that deviations of the dependence of sputtering yield on the incident angle, θ, from the standard (cos θ)⁻¹ dependence can be indicative of a depth dependence in the net energy deposition in the surface region. Information about the sputter ejection mechanism is shown to be obtained only secondarily. We give expressions that allow one to relate the measured dependence of the yields on angle of incidence to the dependence of energy deposition on depth. This is used to analyze results for condensed gas sputtering and heavy ion desorption of organic molecular ions. This analysis indicates that the spatial distribution of excitations produced by the secondary electrons is important in determining these yields. This is also confirmed by observed differences in the yields for transmission and back-sputtering which is a closely related effect.     

三元合金Cu76Ni15Sn9的离子溅射研究

在２７ｋｅＶ Ａｒ⁺离子轰击时,用收集膜技术结合俄歇谱仪（ＡＥＳ）,研究了三元合金Cu₇₆Ni₁₅Sn₉系统的择优溅射行为。同时使用扫描电子显微镜（ＳＥＭ）与电子探针微分析（ＥＰＭＡ）．观察了靶点表面形貌变化并测定了形貌特征微区的合金组份原子的相对百分浓度。结果表明,Ｃｕ原子较Ｎｉ原子、Ｎｉ原子较Ｓｎ原子,在所测定范围（０─６０°）内择优发射。最后讨论了靶点表面形貌特征和“元素局域富集”现象对择优溅射过程的影响。 关键词：     

PKA原子和SKA原子对同位素(溅射)富集度的贡献分析

关键词：     

计及溅射损失的平行板静电场法离子引出和收集

采用粒子模拟-Monte Carlo碰撞(particle in cell_Monte Carlo collision)方法研究了 原子蒸气激光同位素分离工程中一维平行板静电场法离子引出和收集过程，记录引出离子的 能量分布和角度分布，计算离子在收集板上造成的溅射损失.模拟结果表明，增加引出电压 可以缩短引出时间，降低碰撞损失，但是增加了溅射损失，使得收集率降低；增加电子温度 可以缩短引出时间，提高收集率；增加初始等离子体密度将使引出时间增加，收集率降低；而目标同位素丰度较高的情况下，离子引出过程的碰撞损失 关键词： 原子蒸气激光同位素分离 离子引出 溅射     

Atom transport and the change in surface composition during ion implantation in multicomponent materials

A nonstationary system of equations describing the dynamics of the component concentration distributions in a multicomponent material, taking into account implantation, sputtering, external deposition, and diffusion, is obtained. The boundary conditions are formulated. Approximate solutions that make it possible to analyze the effect of different factors on the formation of the concentration in the layers near the surface are given. Zh. Tekh. Fiz. 67, 95–99 (October 1997)