低能氦等离子体低温条件下钨材料的表面形貌

为研究氦等离子体在钨表面造成的表面纳米结构,利用荷兰基础能源研究所Pilot-PSI直线等离子体发生装置在673 K温度下,对钨材料进行了低能（40 eV）高束流强度（4×10²³ m^-2•s^-1）氦等离子体辐照。实验结果表明,辐照后钨材料表面出现了多种不同形态的纳米结构,表面纳米结构和晶粒的表面法向之间存在明显关联。在表面法向为［111］的晶粒表面出现三角形的纳米结构,在［110］取向的晶粒表面出现条带状的纳米结构,而在［001］取向的晶粒表面没有明显的结构出现。晶粒表面的纳米结构尺寸在50 nm左右,高度起伏在5 nm以下。另外,氦等离子体辐照会造成晶界处的高度差,在25 nm左右。分析推测氦等离子体辐照造成的晶粒表面和晶界的形貌可能是由近表面的气泡所导致的。     

轧制钨板在氦源高热流作用下的形貌演化

为研究轧制钨在氦粒子流与高热流协同作用下的表面形貌演化过程,利用德国马普等离子体物理研究所的GLADIS设备对轧制钨板进行了氦源高热流加载实验。结果表明,样品温度对损伤形貌影响显著:低温加载时逐渐发生表面起泡及气泡破裂,且较大尺寸气泡集中分布在近001取向区域;高温加载时观察到多孔/珊瑚状结构;中温加载时则呈现出两种损伤形貌的混合。研究认为,表面损伤形貌的形成由表面起泡和珊瑚状结构演化两个过程共同控制。样品温度影响氦在钨中的扩散,从而影响两者的相对强弱,得到不同的损伤形貌。研究发现,辐照剂量的增加也会使得损伤形貌最终向多孔/珊瑚状结构转化。     

辐照温度对钨材料表面微结构的影响

本文采用100 eV的He+对钨进行辐照实验,考察了辐照温度变化(室温-800°C)对钨材料的表面损伤作用。分别采用扫描电镜(Scanning Electron Microscope,SEM)、透射电镜(Transmission Electron Microscope,TEM)、导电原子力显微镜(Conductive Atomic Force Microscopy,CAFM)以及X射线衍射(X Ray Diffraction,XRD)技术对辐照后样品的微观形貌、内表面缺陷分布以及晶格结构进行了分析。结果表明,He+辐照后钨样品表面出现了纳米绒毛结构层,这种结构层组织间的间距及覆盖率都随辐照温度的增加而增加。纳米结构层会造成样品表面损伤,产生表面离域化,但不会引起钨晶相的改变。通过无损伤的CAFM检测技术证实了样品表面绒毛结构层的形成与样品内表面纳米尺寸He泡的形成有关。     

600℃下氦离子辐照316L不锈钢氦泡形成的研究

在聚变堆与快堆中，高能中子通过（ｎα）反应在结构材料中产生大量的氦。氦聚集形成氦泡，引起材料各种性能的下降；特别是高温下氦流到晶界形成氦泡，使材料发生脆性断裂。对材料中氦泡的形核及长大规律的研究是研究材料中氦脆的基本机制及堆辐照环境中材料微观结构变化...     

He+离子辐照Inconel 718合金表面形貌改变及机理研究

研究了3种不同剂量He⁺离子辐照后Inconel 718合金的形貌变化规律及其形成机理。结果表明,He⁺离子辐照会在合金表面形成纳米多孔结构,其孔径会随辐照剂量的增加而增大。此外,He⁺离子辐照还会破坏合金表面δ相并导致碳化物的持续溅射损耗,且这一现象会随着辐照剂量的增加而愈发严重。由于辐照过程中氦泡间微观应力σ n作用会引起毗邻材料断裂及氦泡合并长大,且辐照溅射作用又会导致氦泡上层薄膜的损耗甚至破裂,因而这也是He⁺离子辐照Inconel 718合金表面纳米多孔结构的形成机制。     

氦离子辐照烧结碳化硅损伤效应研究

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。     

高温下He^＋辐照316L不锈钢时氦泡的形态及氦的俘获

用ＴＥＭ观察６００℃下氦离子辐照３１６Ｌ不锈钢中氦泡的形态及分布，发现氦浓度比较低时，氦泡优先在位错线上形成；随着氦浓度的增大，氦泡在基体中均匀分。在晶粒内及晶界处，拟泡都呈多面体形状，观察的晶界片不存在氦不民的优先生长现象。     

低能离子辐照苏氨酸质量沉积方式的研究

通过研究加入和不加入自由基清除剂条件下，３０ｋｅＶ Ｎ＾＋辐照苏氨酸的剂量与氨基浓度的变化，提出入射的Ｎ＾＋是以氨基的形式沉积在样品分子中，定性和定量解释了低能离子辐射的剂量与氨基残存率的关系。加入自由基清除剂后剂量效应的变化分析结果表明，一部分入射离子是通过自由基反应方程历程沉积在样品分子中。     

钨中氦泡融合条件的分子动力学模拟研究

在托卡马克聚变装置中,钨偏滤器会受到低能高束流的氦等离子体冲刷,导致材料表面形成绒毛状纳米结构或针孔状表面损伤,使钨材料使用性能发生退化,影响等离子体的稳态运行。目前普遍认为,氦致表面损伤的形成与钨表面下氦泡的生长密切相关。钨受到氦等离子体辐照后会在材料的近表层形成高密度的小氦泡,它们可通过融合的方式长大,氦泡的融合是近表层大氦泡形成的关键环节。为了解氦泡的相对位置、温度、氦空位比(He/V)、氦泡初始间距对氦泡融合的影响,本文采用分子动力学方法模拟氦泡在金属钨中的融合过程。结果表明：氦泡的相对位置、温度、He/V、氦泡初始间距都会影响氦泡的融合,但影响的机理并不相同。其中,氦泡的相对位置是影响氦泡融合的关键因素,当氦泡沿〈100〉方向排列时,氦泡易发生融合,而沿 〈111〉方向排列则不易发生融合,其原因是氦泡附近存在各向异性的应力场。温度升高有利于氦泡体积得到更快、更充分的弛豫,进而促进氦泡发生融合。高He/V的氦泡具有较高的压力,更易发生融合。当温度为1 500 K时,2个He/V为3、半径为1 nm的氦泡之间的相互作用距离可达1.28 nm甚至更远,但它们发生融合的最大初始距离为0.96 nm。本研究可促进对钨中氦泡融合机理的理解,为钨中大氦泡的形成提供可能的解释。此外,本研究结果可为大尺度模拟（如动力学蒙特卡罗、团簇动力学）提供相关输入参数用于研究高密度氦泡的长时间演化。     

Deuterium trapping by irradiation damage in tungsten induced by different displacement processes

The deuterium trapping behaviors in tungsten damaged by light ions with lower energy (10 keV C⁺ and 3 keV He⁺) or a heavy ion with higher energy (2.8 MeV Fe²⁺) were compared by means of TDS to understand the effects of cascade collisions on deuterium retention in tungsten. By light ion irradiation, most of deuterium was trapped by vacancies, whose retention was almost saturated at the damage level of 0.2 dpa. For the heavy ion irradiation, the deuterium trapping by voids was found, indicating that cascade collisions by the heavy ion irradiation would create the voids in tungsten. Most of deuterium trapped by the voids was desorbed in higher temperature region compared to that trapped by vacancies. It was also found that deuterium could accumulate in the voids, resulting in the formation of blisters in tungsten.     

The irradiation variation of amorphous alloy FeSiB using for fusion devices induced by 2 MeV He ions

Because of its unique long range disordered structure and numerous free volume, amorphous alloy is considered to be able to accommodate the damage caused by ion bombardment and has good irradiation resistance. 2 MeV He~+ions were selected to irradiate amorphous alloy Fe80 Si7 B13, and it was found that the arrangement of atoms in the amorphous alloy became uneven. In the bubble layer located near the He ion range which was about 3.5 μm from the surface, the local atoms had a tendency of ordered arrangement. Under the irradiation, no obvious damage could be observed on the surface of the amorphous alloy, while the surface roughness increased, which reduced the surface relative reflectivity of the amorphous alloy. After the irradiation, the Fe-based amorphous alloy maintained the soft magnetic performance. The variation of atomic arrangement in the amorphous alloy enhanced its saturation magnetic induction intensity.     

低能氦离子辐照对钨和钼材料的表面损伤作用

钨和钼材料具有高熔点、高热导率、低溅射率等优点成为国际热核实验反应堆计划中面向等离子体材料的候选材料。因此研究钨和钼材料的辐照损伤行为对于认识面向等离子体材料的辐照损伤机制具有重要意义。本文采用120 e V的He+在873 K对钨和钼材料进行辐照实验,利用纳米压痕仪与导电模式原子力显微镜(Conductive Atomic Force Microscopy,CAFM)相结合,原位比较了钨和钼材料在辐照前后的表面形貌、表面微结构以及表层缺陷分布的变化特征。结果表明,低能He+辐照会导致钨和钼材料的近表面产生纳米量级氦泡缺陷,这些氦泡缺陷的存在使得样品表面产生绒毛或波浪状结构。纳米压痕深度分析和扫描电镜的分析结果表明,低能He+辐照会对Mo材料产生明显的刻蚀作用。本工作对于进一步认识低能氦离子辐照对面向等离子体材料的辐照损伤作用具有一定的科学参考意义。     

Ion irradiation effects on the optical properties of tungsten oxide films

The optical changes in amorphous WO₃ film prepared by reactive RF sputtering and irradiated by 200-800 keV oxygen ions were measured to study the relationship between coloration and energy deposition. The color centers were effectively created by ion irradiation with contributions from nuclear collisions and electronic energy loss. The increase in the absorption coefficient was reasonably explained by a first order reaction, whose production rate depended roughly on the total deposited energy. During heat treatment in air atmosphere, transmittance recovery started at 400 K and completed at 550 K. No significant difference was found among films irradiated by different incident energies; therefore indicating that the ion-induced damage structure is not strongly influenced by the type of energy loss.     

Behavior of carbon readsorbed on tungsten during low energy Ar ion irradiation at elevated temperatures

A study of the behavior of carbon sputtered and readsorbed after scattering collisions with particles of surrounding gas on the tungsten surface affected by Ar ion irradiation with the flux equal to 2 × 10¹⁶ cm⁻² s⁻¹ extracted from plasma under 300 V negative bias voltage in the temperature range 370-870 K was performed. The dependence of the W sample weight change on the working gas pressure in the range 0.1-10 Pa was registered and the information was deduced about prevailing sputtering-redeposition processes. The depth profiles of carbon at the tungsten surface were measured. We found that carbon distribution profiles in tungsten depend on the C redeposition rate for fixed ion irradiation parameters. Three regimes have been distinguished: (i) at working gas pressure equal to 5 Pa and more, the C redeposition rate prevails the sample surface erosion rate and the W surface is covered by continuous amorphous carbon film (the C film growth regime), (ii) at working gas pressure equal to about 1 Pa, the C redepostion rate is approximately equal to the erosion rate and the W surface is partially covered by redeposited carbon, and (iii) at working gas pressure less than 0.2 Pa, the erosion rate prevails the C redeposition rate (the W surface erosion regime). In the regime of balanced redeposition and erosion deep C penetration depth into nanocrystalline W was registered.It is suggested that under simultaneous C adsorption and ion irradiation at elevated temperature C adatoms are driven from the W surface into grain boundaries and into the bulk by the difference in chemical potentials between the activated W surface and grain boundaries. As the W surface is covered by amorphous C film, the grain boundaries are blocked and the efficiency of carbon transport decreases.     

H+辐照对不锈钢基体上涂覆W膜的微观研究

对奥氏体不锈钢基体上采用离子束混合技术进行不同厚度的钨膜沉积,沉积后的试样进行了H^ 注入前后的XRD和SEM微观分析,研究了H^ 辐照对W膜的晶体结构和形象的影响。结果表明,沉积的W膜基本上是非晶的,还出现了由于污染造成的钨的氧化物。氢离子的辐照模拟结果表明,少量晶化的W向非晶化转变,污染的氧化物被择优溅射掉。H^ 轰击对W膜表面形貌的影响不大,它仍然致密、均匀、完整且无明显损伤。     

Ion beam erosion of amorphous materials: evolution of surface morphology

In this work we present our results concerning the formation of self-organized nanoscale structures during the bombardment with a low-energy defocused Ar ion beam. We studied glass surfaces because of their physical properties, technological interest and cheapness. The evolution of sample surface was studied ex situ by atomic force microscopy. We found, in agreement with Bradley and Harper, a morphology characterized by a regular ripple structure with the wave vector perpendicular or parallel to the ion beam direction. This structure periodicity was found to vary in the range 90–350 nm with a linear time evolution. In order to gain further information about the sputtering process and for comparison with the existing continuum theories of surface erosion, we studied the scaling behaviour of surface roughness.     

中能氮离子束辐照小麦种子产生自由基的研究

用ＥＳＲ波谱术研究了室温下中能氮离子辐照小麦种子产生的自由基，发现氮离子贯穿和注入小麦种子产生的自由基浓度随剂量的变化具有不同的特征。对氮离子贯穿小麦种子产生的自由基浓度随剂量率的变化规律也进行了研究。     

低温等离子体诱导产生的一种空洞形细胞

通过扫描电镜观察到低温空气等离子体诱导酿酒酵母产生一种特殊的“空洞”形细胞。空洞细胞的形态特征及生长特性提示,空洞的形成可能是由于低温空气等离子体所致的细胞诱变效应,而不是等离子体对细胞表面的直接损伤。结果提示低温空气等离子体对细胞的损伤及诱变作用可能具有复杂的作用机制。     

钨和铼的色层分离研究

以＾１８７Ｗ，＾１８８Ｗ－＾１８８Ｒｅ为示踪剂，为Ｗ和Ｒｅ在阴离子交换色层柱和酸性Ａｌ２Ｏ３色层柱上的吸附和解吸行为进行了系统研究，给出了Ｗ和Ｒｅ的放射化学分离程序，实验结果表明，无论是阴离子交换色层柱还是酸性氧化铝层柱都可使钨，铼达到满意的分离，推荐的分离程序可用于无载体＾１８６Ｒｅ的制备。