Periodical structure formation on a magnesium and aluminum surface under high power ion beam irradiation of nanosecond duration

The formation of periodical structures, and also, micro- and nanoparticles on a polycrystalline magnesium and aluminum surface under high power proton-carbon beam irradiation has been investigated. The spatial parameters of these structures and particle sizes have been determined. The possible mechanisms for periodical structure formation have been considered.     

Nanostructuring of the surface of aluminum alloys under irradiation by a high-power ion beam

The surface morphology of aluminum alloys under irradiation by a high-power nanosecond ion beam with a low current density is investigated. The possible factors responsible for the change in the surface relief are considered.     

Modification and smoothing of patterned surface by gas cluster ion beam irradiation

Surface modification and smoothing of patterned surfaces with gas cluster ion beams were studied. In this work, line and space patterns having various intervals and depths were created on amorphous carbon films by focused Ga⁺ ion beams, and subsequently, Ar GCIB irradiations on the pattern were performed. When the acceleration voltage of Ar cluster ions was 20 kV, the grooves, whose interval was below 200 nm, were planarized. However, it required much higher ion dose for wider interval of patterns. It is estimated that the distance of lateral motions induced by one cluster ion impact defines the spatial wavelength dependence of smoothing.     

Interaction of beam and coated metals at high power continuous irradiation

The beam-matter interaction with various coating effects has received continued attention in the high power laser community. Previous works suggest that coatings promote target damage when compared to beaming on uncoated surface. Three types of paint coatings (acrylic urethane, silicone alkyd and stealth blend) and a water coat on metals (Al, Ti and STS) are irradiated with a CO₂ laser. Both strain and temperature measurements are provided for assessing the instantaneous response characteristics of each coating on different metals. A selective combination of surface coats with metals has been proven to be effective in either preventing or enhancing damage, both thermal and mechanical, associated with focused beaming on a target.     

Effect of a displaced atom on a bulk surface topography induced by ion beam irradiation

The formation of a ripple topography on the surface of an amorphous solid at a small (subcritical) incidence angle of ions was studied by the statistical tests method. It was found that a pattern is formed if the sputtering of atoms in the uppermost layer of the target is taken into account along with the processes occurring in the bulk. In particular, the movement of the atoms displaced during the development of a cascade of impacts must be considered for the formation of a ripple topography with crests and valleys oriented along the beam projection onto the target surface.     

Irradiation effect of yttria-stabilized zirconia by high dose dual ion beam irradiation

Yttria-stabilized zirconia （YSZ） is irradiated with 2.0-MeV Au2＋ ions and 30-keV He＋ ions. Three types of He, Au, Au ＋ He （successively） ion irradiation are performed. The maximum damage level of a sequential dual ion beam implanted sample is smaller than single Au ion implanted sample. A comparable volume swelling is found in a sequential dual ion beam irradiated sample and it is also found in a single Au ion implanted sample. Both effects can be explained by the partial reorganization of the dislocation network into weakly damaged regions in the dual ion beam implanted YSZ. A vacancy-assisted helium trapping/diffusion mechanism in the dual ion beam irradiated condition is discussed. No phase transformation or amorphization behavior happens in all types of ion irradiated YSZ.     

Evolution of surface morphology of NiO thin films under swift heavy ion irradiation

NiO nanoparticle thin films grown on Si substrates were irradiated by 107 MeV Ag⁸⁺ ions. The films were characterized by glancing angle X-ray diffraction and atomic force microscopy. Ag ion irradiation was found to influence the shape and size of the nanoparticles. The pristine NiO film consisted of uniform size (∼100 nm along major axis and ∼55 nm along minor axis) elliptical particles, which changed to also of uniform size (∼63 nm) circular shape particles on irradiation at a fluence of 3 × 10¹³ ions cm⁻². Comparison of XRD line width analysis and AFM data revealed that the particles in the pristine films are single crystalline, which turn to polycrystalline on irradiation with 107 MeV Ag ions.     

Damage of beryllium surface under irradiation with a high-current electron beam

Radiation damage of a beryllium surface by a high-current electron beam at the GSEP-3 accelerator is considered. The degree of damage of beryllium samples has been determined. The temperature fields inside the sample and the distributions of thermal stresses have been calculated. The reasons for beryllium surface cracking formation have been found. The concentrations of point defects have been calculated. The possible reasons for an increase in microhardness of the irradiated beryllium surface layer are discussed.     

The formation of developed morphology on the indium phosphide surface by ion argon beam sputtering

Self-organizing structures on the InP surface that are formed by ion-beam sputtering in the energy range 0.1–15 keV are investigated. It is shown that the processing of the InP surface by monochromatic argon beams can give rise to the formation of two, “grass” and “cone-in-pit,” morphologies. The formation of the relief is treated in terms of a qualitative model including the processes of sputtering, cascade mixing, and surface transport. The model adequately predicts the fluence dependence of the density and size of morphological features. In addition, it enables one to clarify conditions under which the morphologies form, as well as to explain the effect of target temperature on the demarcation line between the morphologies. It is demonstrated that the morphology may become anisotropic in the case of mask etching. In particular, the application of regularly spaced strips as masks makes it possible to produce a texture-like surface structure.     

Preparation of highly oriented poly-diacetylene films with ion beam irradiation

Abstract

Substituting metallic or rare-earth atoms or removing O in the superconductor YBa₂Cu₃O₇ usually has a strong effect on the superconducting properties. We have made extensive XAFS studies on Co, Fe, Ni, Zn, Gd, and Pr substituted materials including some thin film samples. In nearly all cases, significant distortions are found. Although the lattice constant change is small (< 0.05 Å) the local distortions can be significant larger (～ 0.1 to 0.3 Å). The observed large local distortions of the lattice together with a change in the charge distribution at a site indicate that the interior of the unit cell is easily distorted. The correlation of a strong Tc suppression with large local distortions suggests that distortions of the nearby layers must play a significant role in models for superconductivity in high Tc materials.     

Effects of evolving surface morphology on yield during focused ion beam milling of carbon

We investigate evolving surface morphology during focused ion beam bombardment of C and determine its effects on sputter yield over a large range of ion dose (10¹⁷-10¹⁹ ions/cm²) and incidence angles (Θ = 0-80°). Carbon bombarded by 20 keV Ga⁺ either retains a smooth sputtered surface or develops one of two rough surface morphologies (sinusoidal ripples or steps/terraces) depending on the angle of ion incidence. For conditions that lead to smooth sputter-eroded surfaces there is no change in yield with ion dose after erosion of the solid commences. However, for all conditions that lead to surface roughening we observe coarsening of morphology with increased ion dose and a concomitant decrease in yield. A decrease in yield occurs as surface ripples increase wavelength and, for large Θ, as step/terrace morphologies evolve. The yield also decreases with dose as rippled surfaces transition to have steps and terraces at Θ = 75°. Similar trends of decreasing yield are found for H₂O-assisted focused ion beam milling. The effects of changing surface morphology on yield are explained by the varying incidence angles exposed to the high-energy beam.     

Formation of disperse particles under high-power ion beam irradiation of metals with a coating

Metal systems based on aluminum and copper coated with nickel irradiated by a high-power ion beam of nanosecond duration have been studied by scanning electron microscopy and local X-ray microanalysis. Dispersed particles of micro- and nanosizes have been found on the surface target. Their composition and formation mechanism differ. It has been shown that microparticles were formed during mixing of film and target atoms and consisted of corresponding components. Nanoparticles were mainly composed of the coating material, and their formation was associated with the dispersion of the Ni film due to the presence of a thin oxide layer on the sample surface. The deposition of Ni ablated by a high-power ion beam can affect the formation of nanoparticles.     

Graphitization of a diamond surface upon high-dose ion bombardment

Results from structural and morphological studies, measurements of the sheet electrical resistance, and estimating resistivity ρ_m of a graphite-like conducting surface layer formed upon high-dose irradiation of the (111) face of a synthetic diamond with Ar⁺ ions at an energy of 30 keV and a target temperature of 400°C are presented. It is found that the orienting effect of the diamond lattice is visible in the suppression of the formation of graphite crystallites with axis c perpendicular to the surface. The thickness of the modified layer is 40–50 nm, and its sheet resistance is 0.5 kΩ/sq. Resistivity ρ_m = 20–25 μΩ m of the modified layer lies within the range of ρ values of graphite and glassy carbon materials.     

Low temperature ion beam irradiation of gallium films

Ga-films in the amorphous, the -Ga, and the -Ga phase have been irradiated at low temperatures with Ar-ions and He-ions at energies 275 keV and 200 keV, respectively. The -phase can be transformed into the amorphous state by Ar-ion irradiation but not by He-ion irradiation. Rather small Ar-fluences <10¹⁴ ions/cm² are sufficient. The -phase is stable with respect to irradiation with Ar- and He-ions at small fluences. The as-quench condensed amorphous phase is stable with respect to Ar-ion irradiation, however, it transforms into the -phase at He-ion irradiation. The different short range order of the - and -phase is thought to be responsible for the different behavior at ion irradiation.This work is dedicated to Professor Dr. S. Methfessel on the occasion of his 60th birthday     

利用功率谱密度评价离子束抛光光学元件表面粗糙度

利用功率谱密度(PSD)评价光学表面粗糙度具有传统评价手段(Ra)所不具备的优势。给出了功率谱密度的计算方法,以及抽样方向与一维PSD曲线的关系。在离子束抛光K9玻璃实验中引入PSD曲线,以评价抛光光学零件的光学表面粗糙度,结合PSD曲线与Ra值能够更全面的指导光学加工。     

Increased wear resistance and positron annihilation in Cu exposed to high power ion beam

This paper concerns primary results of defect profiles in copper samples irradiated by a high power ion beam. Positron sensitive defects were found to be responsible for increased abrasive wear resistance. The HPIB modified layer was conventionally divided into three regions, which differed in defect concentration and defect types. The region of formation of dislocation loops, prisms and vacancy twins correlated with maximum increased abrasive wear resistance. Isochronous annealing of the HPIB irradiated samples has also been investigated.     

高功率毫米波辐照对秀丽线虫行为学和细胞形态学的影响

采用角锥喇叭天线,使用不同输出平均功率的毫米波激光辐照秀丽线虫,采用实时显微摄像系统记录线虫行为学变化,并使用体视显微镜观察线虫细胞形态学变化。受照射后自由活动的秀丽线虫能够快速逃离高功率毫米波的辐照区域。当受输出平均功率为10 W和12 W辐照后,线虫先后出现运动速度增加、运动速度减慢直至身体僵直不动的变化过程。当输出平均功率为5 W时,线虫出现热耐受现象。细胞形态学观察结果显示:辐照后的线虫腹中卵细胞核结构出现不同程度的异常。高功率毫米波辐照可显著影响线虫的行为学特征及细胞形态学,同时说明秀丽线虫是可适用于高功率毫米波生物效应研究的模式生物之一。     

Erosion of the GaAs target under irradiation by a high-power pulsed ion beam

The results of examination of the GaAs-target erosion under irradiation by a high-power pulsed ion beam are reported. In the experiments, use was made of a high-power pulsed ion source with the following parameters: ion energy — 250 keV, target current density — 350 A/cm², pulse duration — 80 ns, target energy density — up to 7 J/cm². The target erosion coefficient and its dependence on the number of successive pulses are measured. It is found that the surface roughness parameter is increased with the number of successive beam pulses. A regular structure of surface relief is observed to form in the case where the number of pulses > 20–40. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 66–70, January, 2007.     

Tuning of ripple patterns and wetting dynamics of Si (100) surface using ion beam irradiation

Ripple patterns on Si (100) surface have been fabricated using 200 keV Ar⁺ oblique ion beam irradiation. Dynamical evolution of patterns is studied for the fluences ranging from 3 × 10¹⁷ ions/cm² to 3 × 10¹⁸ ions/cm². AFM study reveals that the exponential growth of roughness with stable wavelength of ripples up to higher fluence values is lying in the linear regime of Continuum models. Stylus Profilometer measurement was carried out to emphasize the role of sputtering induced surface etching in ripple formation. Rutherford Backscattering Spectroscopy shows the incorporation of Ar in the near surface region. Observed growth of ripples is discussed in the framework of existing models of surface patterning. Role of ion beam sputtering induced surface etching is emphasized in formation of ripples. In addition, the wetting study is performed to demonstrate the possibility of engineering the hydrophilicity of ripple patterned Si (100) surface.     

高功率离子束辐照膜基双层靶温度场的数值研究

采用TRIM程序模拟高功率离子束与铝基钛膜双层靶的相互作用.计算了束流在靶材内的能量沉积及分布情况,并以此沉积能量为热源项,采用有限差分方法求解非线性热传导方程,得到了温度场的分布规律,分析了不同离子流密度对界面物质状态的影响.结果表明,离子束电流密度在100—200 A/cm²之间取值时,脉冲结束后界面处两种物质均达到熔融状态.