Effect of ion-beam assisted deposition on the film stresses of TiO_2 and SiO_2 and stress control

Based on Hartmann-Shack sensor technique, an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2, and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition. The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details, and the stress control methodologies using on-line adjustment and film doping were put forward. The results show that the film stress value of TiO2 prepared by ion-beam assisted deposition is 40 MPa lower than that prepared by conventional process, and the stress of TiO2 film changes gradually from tensile stress into compressive stress with increasing ion energy; while the film stress of SiO2 is a tensile stress under ion-beam assisted deposition because of the ion-beam sputtering effect, and the film refractive index decreases with increasing ion energy. A dynamic film stress control can be achieved through in-situ adjustment of the processing parameters based on the online film stress measuring technique, and the intrinsic stress of film can be effectively changed through film doping.

Effects of the ion-beam voltage on the properties of the diamond-like carbon thin film prepared by ion-beam sputtering deposition

Diamond-like carbon （DLC） thin film is one of the most widely used optical thin films. The fraction of chemical bondings has a great influence on the properties of the DLC film. In this work, DLC thin films are prepared by ion-beam sputtering deposition in Ar and CH4 mixtures with graphite as the target. The influences of the ion-beam voltage on the surface morphology, chemical structure, mechanical and infrared optical properties of the DLC films are investigated by atomic force microscopy （AFM）, Raman spectroscopy, nanoindentation, and Fourier transform infrared （FTIR） spec- troscopy, respectively. The results show that the surface of the film is uniform and smooth. The film contains sp2 and sp3 hybridized carbon bondings. The film prepared by lower ion beam voltage has a higher sp3 bonding content. It is found that the hardness of DLC films increases with reducing ion-beam voltage, which can be attributed to an increase in the fraction of sp3 carbon bondings in the DLC film. The optical constants can be obtained by the whole infrared optical spectrum fitting with the transmittance spectrum. The refractive index increases with the decrease of the ion-beam voltage, while the extinction coefficient decreases.

Bioeffects of Low Energy Ion-Beam Implantation and Vacuum Treatment on M_1 Arabidopsis Thaliana

Vacuum treatment and ion-beam bombardment are two major processes in the low energy ion-beam implantation. To accurately study the contributions of these two major factors to the bioeffects separately, the M1 generation variation of Arabidopsis thaliana with ion-beam implantation and vacuum treatment were compared through a series of key plant development parameters including morphological observation, biochemical assay and RAPD （random amplified polymorphic DNA） analysis. The results showed that ion-beam implantation had obvious effect on almost all of these parameters, and the vacuum treatment had some impacts on several morphological parameters such as the bolting time and the length of the primary stem. Taking the results together, the indication is that vacuum treatment has some slight contributions to the bioeffects of ion-beam implantation while ion-beam bombardment itself is the major creator of the bioeffects.

Ion-Beam Surface Modification of Strut Dowel Used in ITER PF Support

In this paper, surface modification of the strut dowel used in ITER PF support is reported. Different ions （nitrogen/titanium） with different doses are implanted into the surface of strut dowel. The result of Auger Electron Spectroscopy （AES） indicates that nitrogen can be implanted more deeply than titanium under the implantation condition of 60 kV accelerating voltage and a dose of 8×10^17/cm2 nitrogen. Surface Micro Hardness （SMH） and wear resistance are improved remarkably. Further SEM observation shows that there are no obvious scratches and damages after wear test.

Studies on Ion-Beam Modified Hydrogen Evolution Electrodes

he present paper focuses on the modifying effects of ion beam mixing, ion im-planting and ion sputtering on hydrogen evolution electrodes. It was discovered thatthe four types of electrodes possessed excellent catalytic activity in acid or alkalinemedia and potential stability in long term electrolysis of water under high currentdensity. Their stability and applying life-span greatly surpass those of other elec-trodes activated by electrodepositing and other method. The effects of temperatureand roughness on function of electrodes were also examined. XPS and AES wereapplied to analyse the surface composition and bond states of the electrodes, andthe distribution of concentration varying with depth, and to explain the law of theexperiments .

Observation of double pseudowaves in an ion-beam-plasma system

Pseudowaves, known as burst-ion signals, which are different from plasma normal modes, exist frequently in ion- wave excitation experiments when launching the waves by applying a pulsed voltage to a negatively biased grid. In previous experiments, only one kind of the pseudowave was observed. In this paper, we report the observation and identification of double pseudowaves in an ion-beam-plasma system. These pseudowaves originate from two ion groups： the burst of the beam ions and the burst of the background ions. It was observed that the burst of the background ions was in the case of high ion beam energy, while the burst of the beam ions was in the case of low ion beam energy. By observing the dependence of the signal velocities on the characteristics of the excitation voltage, these pseudowaves can be identified. It was also observed that the burst ion signal originating from the background ions can interact with slow beam mode and that originating from the beam ions can interact with fast beam mode.

Upstream ion wave excitation in an ion-beam–plasma system

Plasma normal modes in ion-beam–plasma systems were experimentally investigated previously only for the waves propagating in the downstream（along the beam） direction. In this paper, the ion wave excitation and propagation in the upstream（against the beam） direction in an ion-beam–plasma system were experimentally studied in a double plasma device. The waves were launched by applying a ramp voltage to a negatively biased excitation grid. Two kinds of wave signals were detected, one is a particle signal composed of burst ions and the other is an ion-acoustic signal arising from the background plasma. These signals were identified by the dependence of the signal velocities on the characteristics of the ramp voltage. The velocity of the burst ion signal increases with the decrease of the rise time and the increase of the peak-to-peak amplitude of the applied ramp voltage while that of the ion-acoustic signal is independent of these parameters.By adjusting these parameters such that the burst ion velocity approaches to the ion-acoustic velocity, the wave–particle interaction can be observed.

Purification and Properties of a New L-Sorbose Dehydrogenase Accelerative Protein from Bacillus megaterium Bred by Ion-Beam Implantation

Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein （SAP） to accelerate the activity of L-sorbose dehydrogenase （SDH） of Gluconobacter oxydans in the 2-keto-L-gulonic acid （2KLG） fermentation from L-sorbose by the mixed culture of B. megaterium BM302 and G. oxydans. The SAP purified by three chromatographic steps gave 35-fold purification with a yield of 13% and a specific activity of 5.21 units/mg protein. The molecular weight of the purified SAP was about 58 kDa. The SDH accelerative activity of SAP at pH 7 and 50℃ was the highest. Additionally, it retained 60% activity at a pH range of 6.5 ～ 10 and was stable at 20℃ ～ 60℃. After 0.32-unit SAP was added to the single cultured G. oxydans strains, the SDH activity was apparently accelerated and the 2KLG yield of GO29, GO112, GO and GI13 was enhanced 2.1, 3.3, 3.5 and 2.9 folds respectively over that of the strains without the addition of SAP.

Control of Beam Energy and Flux Ratio in an Ion-Beam-Background Plasma System Produced in a Double Plasma Device

Plasmas containing ion beams have various applications both in plasma technology and in fundamental research. The ion beam energy and flux are the two factors characterizing the beam properties. Previous studies have not achieved the independent adjustment of these two parameters. In this paper, an ion-beam-background-plasma system was produced with hotcathode discharge in a double plasma device separated by two adjacent grids, with which the beam energy and flux ratio （the ratio between the beam flux and total ion flux） can be controlled independently. It is shown that the discharge voltage （i.e., voltage across the hot-cathode and anode） and the voltage drop between the two separation grids can be used to effectively control the beam energy while the flux ratio is not affected by these voltages. The flux ratio depends sensitively on hot-filaments heating current whose influence on the beam energy is relatively weak, and thus enabling approximate control of the flux ratio

A New hcp Phase Formed in the Ni-Nb System during Ion-beam-assisted Deposition

The Ni80Nb20 films were prepared by ion beam assisted deposition (IBAD) with various Ar+ ion energies. A phase evolution of fcc→amorphous→Ni+Nb→Ni+hcp was observed with the increasing of ion beam energy from 2 keV to 8 keV. When bombarded by Ar+ ions of 8 keV during deposition, a new crystalline phase with hcp structure was obtained, of which the lattice parameters are a=0.286 nm and c=0.483 nm, different from those of the similar A3B-type hcp phase previously reported. The experimental results were discussed in terms of thermodynamics and restricted kinetic conditions in the far-from-equilibrium process of IBAD. The formation of hep phase may also be related to the valence electron effect.

Research on the Distant Hybrids of Wheat Obtained via Low-Energy Ion-Beam Implantation

The whole DNA of soybean was implanted into four varieties of wheat of Zhongyu 5, Huaiyin 9628, Wenyou 1, Jimai 5 respectively via ion-beam mediation. There were 5 plants obtained whose protein content was higher than 18.5 %, the highest one was 21.44 %. There were 3 plants obtained whose protein content was lower than 11.5%, the lowest one was 10.96%. We can see that the whole DNA of soybean transformed into wheat via ion beam implantation can induce the increase in wheat protein content dramatically. The result also shows that the transformation efficiency of different gene types of wheat receptor varies greatly that the implanting time has a certain effect on the efficiency of transformation.

类氦C离子诱发不同金属厚靶原子的K-X射线

利用中国原子能科学研究院HI-13MV串列加速器上提供的动能为15—55 MeV的类氦C离子分别轰击Fe,Ni,Nb和Mo金属厚靶,采用HpGe探测器测量了K-X射线,获得了相应的K-X射线的发射截面.本文中由于各个靶原子外壳层电离度的不同,类氦C离子与Fe,Ni靶原子相互作用发射的K_(β)与K_(α)X射线的分支强度比随入射离子动能增加而减小,而Nb,Mo靶原子发射的K-X射线分支强度比变化不明显.利用厚靶截面公式计算了靶原子K-X射线的发射截面,并与不同的理论模型及质子的结果进行了对比.结果表明随类氦C离子动能的增大,Fe,Ni靶原子发射的K_(β)与K_(α)X射线的总产生截面与考虑多电离的两体碰撞近似修正模型最为符合Nb,Mo靶原子发射的K_(β)与K_(α)X射线的总产生截面与平面波恩近似模型的理论值最为接近.质子与单核子C离子能量相同时,质子比类氦C离子激发不同靶的K-X射线产生截面约小3个数量级.

原子力显微镜-扫描电子显微镜共定位表征系统的研发与应用

微纳加工过程中,常有样品需要进行聚焦离子束(FIB)溅射、切割,扫描电子显微镜(SEM)以及原子力显微镜(AFM)表征,而这三类仪器都需要将样品固定在样品台上才可测试,固定不佳会影响表征结果.但固定好的样品在不同仪器之间转移、拆卸、再固定的过程中极易受到破坏.基于以上问题,设计了AFM-SEM-FIB样品共定位系统,可实现样品在此三种仪器之间的无损转移及共定位,避免珍贵样品破坏及目标丢失,以及解决AFM扫描无法控制方向、迅速调整位点等问题.在微纳表征中有优异的表现,系统已被开发成产品并量产销售.

高能束表面改性技术在航空领域的应用

高能束表面改性适用于各种金属和合金,能够显著提升材料表面硬度、耐磨、耐蚀等性能指标,是航空部件实现性能提升的有效手段之一。本文总结了6种高能束表面改性技术的基本原理、设备构成和改性应用,其中激光相变硬化通过马氏体相变强化金属材料表面;激光熔覆通过选择不同粉末实现表面修复和表面性能提升,重点在于控制裂纹缺陷;激光冲击强化可有效解决航空发动机部件高周疲劳断裂问题;强流脉冲电子束和强流脉冲离子束一方面需要提高设备的性能和运行稳定性,另一方面要针对航空部件应用开展深入研究;而离子束辅助沉积则可以通过制备固体润滑涂层实现对微动磨损的有效防护。最后,提出对高能束表面改性机理深入研究、发展专业化智能化装备和实现多种束源复合与集成的发展方向。

Si基SiC薄膜物理制备工艺研究进展

随着微纳电子器件集成化程度不断提高,用Si基SiC薄膜取代SiC体单晶引起了人们极大的兴趣,这种方法不仅有利于降低生产成本,还能与Si基大规模集成电路兼容。文章综述了磁控溅射、分子束外延、离子束溅射、离子注入4种物理制备Si基SiC薄膜主要工艺的研究进展,简单阐述了各种工艺对薄膜性能的影响,对各种工艺的优缺点和存在的问题进行了评述,同时指明了Si基SiC薄膜领域未来的发展方向。

基于纳剂量学量模型的碳离子束相对生物学效应计算

目前癌症严重影响人类的健康,迫切需要一种能有效治疗癌症的手段.碳离子束由于其具有较高的生物学效应和独特的布拉格峰,被认为是极具有潜在价值的放疗射线.主要利用基于纳剂量学量的LNDM(Logistic NanoDosimetry Model)模型计算不同入射能量碳离子束在水模体的相对生物学效应(Relative Biologica Effectiveness,RBE).使用GATE模拟工具得到碳离子束及其碎片在水模体中不同深度的能谱和剂量,利用预先计算的带电离子纳剂量学量数据库计算得到碳离子束的四个纳剂量学量M1、■,基于LNDM模型计算碳离子束的RBE.结果表明,碳离子束的RBE峰值随着入射能量的增加而逐渐降低,并且RBE峰值出现在布拉格峰下降沿附近.

长脉冲高功率负离子源实验平台量热靶研制

[目的]高能、强流、长脉冲中性束负离子源技术是磁约束聚变堆等离子体达到燃烧条件的核心技术之一。为满足长脉冲高功率负离子源实验平台200 kV/20 A参数下的束诊断需求,研制了用于截获负离子束或中性束、诊断两种束功率密度分布和束发散角以及负离子的中性化效率等性能参数的量热靶。[方法]根据现有的实验平台真空室结构和引出电极尺寸,利用matlab程序获得了该参数下,束发散角为1°时的负离子束在量热靶前端处的功率密度分布和束斑尺寸,进而设计了V字形靶板的量热靶物理结构;在此基础上采用Workbench软件对无氧铜V字形靶板结构进行满功率运行状态下的热负荷模拟计算,获得了水流量为80 m~3/h条件下的量热靶长脉冲运行时的温度分布,最高温度为610℃。[结果]根据模拟计算结果,结合实验平台工程结构和诊断需求,完成了量热靶的工程设计。[结论]量热靶采用磁流体真空密封,实现V字形靶板开合,靶板背面布置了热电偶阵列实时监测靶板温度。量热靶工程结构紧凑,安装尺寸能够兼容离子束流诊断真空室和中性束流诊断真空室,满足诊断需求,能够长脉冲安全运行。

碳离子束辐照对马铃薯组培苗生长及生理特性的影响

为研究高能碳离子束对马铃薯组培苗茎切段的影响,以马铃薯品种‘新大坪’的组培苗茎切段为研究材料,设置4个辐照剂量梯度对其进行辐照处理,测定植株致死率、生根率、侧芽形成率、形态变异率以及叶片生理指标,确定‘新大坪’组培苗茎切段的半致死辐照剂量。结果表明:辐照剂量与致死率之间的关系呈正相关性;组培苗茎切段的再生植株表型变化主要为叶片不对称、叶缘不规则、茎变异伸长、叶片丛生和叶片粘连等;随辐照剂量升高,超氧化物歧化酶、过氧化物酶和过氧化氢酶活性呈先升后降的趋势;丙二醛含量则呈先升后降,随后又升高的现象。利用线性回归方程计算‘新大坪’的半致死辐照剂量为20.37 Gy。

重离子辐照育种对西蓝花幼苗生长及生理特性的影响

西蓝花(Brassica oleracea var.italica)是我国重要的蔬菜作物之一,其种子主要源于进口,亟需开发属于我国的创新型品种。为探究高能重离子束对西蓝花的当代生物学效应,本研究采用碳离子束辐照西蓝花种子,检测其幼苗期的生长指标、抗氧化酶活性、光合指标和叶绿素荧光等参数。结果表明:100~500 Gy的辐照对种子的萌发没有显著影响,600 Gy显著抑制其萌发。100~600 Gy辐照后根长、芽长、苗高、叶面积总体上随剂量增加而降低。碳离子束辐照西蓝花的半致死剂量(Median lethal dose,LD50)为415.89 Gy,使根长减半的剂量为495.12 Gy。辐照后幼苗的超氧化物歧化酶(Superoxide dismutase,SOD)和过氧化物酶(Peroxidase,POD)活性均高于对照,过氧化氢酶(Catalase,CAT)的活性低于对照,400 Gy辐照后丙二醛(Malondialdehyde,MDA)含量显著升高。随吸收剂量的增加光合色素(叶绿素a、叶绿素b和类胡萝卜素)呈现先升高再降低的趋势,最高值出现在300 Gy处。净光合作用、蒸腾速率和气孔导度均与吸收剂量负相关,辐照后非光合淬灭系数显著升高。结果表明,重离子束辐照抑制了西蓝花植株的生长,影响了抗氧化酶活性和光合作用。本研究为西蓝花的重离子束辐照诱变育种提供了基础数据。

半球谐振子超精密修调方法研究

目的研究因谐振子质量缺陷而引起的频率裂解机制,进而对刚性轴位置进行质量高分辨率可控去除,提高陀螺精度。方法首先基于多区域配合划分法建立半球谐振子高精度有限元仿真模型,分析质量大小与位置对谐振子频差的影响规律。其次搭建谐振子振动特性检测平台,利用拍频法实现其频差值和刚性轴位置的精确辨识。最后结合仿真与辨识结果以及离子束加工方法确定谐振子超精密修调方案。结果优化网格划分方法后,谐振子有限元模型频差值小于0.0001Hz,当修调定位误差相同时,在一个范围内的质量去除比单点质量去除的修调效率更高;谐振子质量缺陷四次谐波刚性轴位置辨识精度可达0.1°,与常见的幅值法相比,其精度提高了一个数量级;通过三次点线结合方式进行质量修调后,谐振子频差值小于0.001Hz,修调效率与精度得到了提升。结论提出的谐振子仿真模型、振动特性测试方法以及离子束修调工艺精度较高且可行性较强,对实现半球谐振子性能高精度检测以及高质量加工具有重要意义。