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Helium-containing Ti films are prepared using magnetron sputtering in the helium–argon atmosphere. Isochronal annealing at different temperatures for an hour is employed to reveal the behaviour of helium bubble growth. Ion beam analysis is used to measure the retained helium content. Helium can release largely when annealing above 970 K. A thermal helium desorption spectroscopy system is constructed for assessment of the evolution of helium bubbles in the annealed samples by linear heating (0.4 K/s) from room temperature to 1500 K. Also, Doppler broadening measurements of positron annihilation radiation spectrum are performed by using changeable energy positron beam. Bubble coarsening evolves gradually below 680 K, migration and coalescence of small bubbles dominates in the range of 680–970 K, and the Ostwald ripening mechanism enlarges the bubbles with a massive release above 970 K.

A new method prepared for helium and hydrogen co-containing Zr films is presented to simulate aging metal tritides, in which direct current magnetron sputtering with a He/H/Ar mixture is used. The retained amount and depth profiles of helium and hydrogen are determined by elastic recoil detection analysis. Thermal desorption spectrometry is applied to investigate He thermal release and the effect of hydrogen. It is found that the high-temperature peaks with a large mount of helium release obviously shifted toward lower temperature at high hydrogen concentration, especially at the hydride transformation region, and that the shapes of the release peaks also changed due to the additional hydrogen. However, at the low-temperature releasing region the peak intense decreases when phase transformation takes place. The mechanism of helium thermal release and the effect of hydrogen are also discussed.

The incident angle dependence of secondary electron emission induced by a swift H2+ ion impinging on carbon is studied using the Monte Carlo method combined with the semiempirical theory. The relationships both between the electron emission yield and the project angle and between the statistics and the projectile angle are investigated. The results show that the backward electron emission yield deviates from the inverse cosine law, due to the effect of the valence electrons of H2+. The ratio of the forward electron emission yield to the backward electron emission yield at the inclining incidence is different from that at the normal incidence. The statistical distribution of electron emission is independent of the incident angle. The value of b, the deviation parameter from the Poisson distribution, increases with projectile energy.

By using ion beam sputtering, an 85-A thick nickel layer was deposited on the Zr–Al alloy (non-evaporable getter) to improve the characteristic of the hydrogen absorption. The presputtering for 15 min to clean the surface passivation layer and the vacuum heating treatment of the sample at 750 degrees C for 1 h for surface alloying can improve the ability of the gas absorption. The gas absorption experiments show fast absorption kinetics of the hydrogen pumping and good durability against contaminable gases. The Rutherford-back-scattering spectra and the secondary ion mass spectroscopy demonstrate the formation of an alloy of Zr, Al, and Ni in the near-surface area after the thermal process. The elastic recoil detection analysis indicates that the sample holds the original high capacity of hydrogen.

The hydrogenation properties of Zr samples with and without an Ni overlayer under various plasma conditions were investigated by means of non-Rutherford backscattering and elastic recoil detection analysis. The theoretical maximum hydrogen capacity, 66.7 at%, could be achieved at a hydrogen absolute pressure of ~2 Pa and a substrate temperature of ~393 K for a plasma irradiation of only 10 min; this was significantly greater than that for gas hydrogenation under the same hydrogen pressure and substrate temperature. It was also found that the C and O contamination on the sample surface strongly influences the hydrogenation, and that the maximum equilibrium hydrogen content drops dramatically with the increasing total contamination. In addition, the influence of the Ni overlayer on the plasma hydrogenation is discussed.

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°C or to 550°C. 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 of C14, C15, Zr and V, but the content of C15 phase is not higher compared with that in the bulk material.

Layered MAX phase ternary compounds (M = early transition metals, A = group A elements, and X = C or N) show promise of wide applications in many applied fields because these compounds have combined ceramic and metallic properties. As an exemple of the MAX phase family, Ti3SiC2 exhibits a high melting temperature, high electrical and thermal conductivities, and an excellent resistance to oxidation and thermal shock. Particularly, it possesses unusual mechanical properties, such as easy machinability, high Young's modulus, thus it is considered as a candidate in advanced nuclear reactors.In this work, we investigate the effect of hydrogen and helium on the cleavage fracture of Ti3SiC2 in order to evaluate the reliability of Ti3SiC2 used in nuclear industry. We have performed first-principles mechanical calculations by using the density functional theory as implemented in the Cambridge Serial Total Energy Package code. Uniaxial tensile simulations along c-axis have been done to calculate the stress-strain curve and the cleavage energy for each interlayer of Ti3SiC2. It is found that Ti3SiC2 has the cleavage characteristics, and the habit cleavage plane starts from Si-Ti interlayer because of relatively weak Si-Ti bond. Hydrogen and helium always accumulate in the Si layer. Helium decreases largely the critical stress of cleavage fracture of Ti3SiC2. In contrast, hydrogen does not efficiently affect the cleavage fracture in Ti3SiC2. The difference between helium and hydrogen behaviors in Ti3SiC2 originates primarily from the difference of electronic hybridization with lattice atoms of Ti3SiC2. For helium, the neighboring Si atoms will be ejected by helium atoms, and the Si-Ti bonds will be broken, thus resulting in the cleavage fracture. However, for hydrogen, it is primarily hybridized with the s states of neighboring Si atoms, which does not severely disturb the p-d hybridization between Si and Ti atoms. Thus, the cleavage fracture from Si-Ti interlayer is hardly aggravated in the presence of hydrogen. Fortunately, Ti3SiC2 has a self-repair ability at high temperatures. It will desorb helium atoms at high helium pressure through Si layers. This behavior will alleviate the cleavage fracture induced by helium. In summary, Ti3SiC2 may be a potential material applied in light water or other fission reactors in the future.

Titanium thin films incorporated with helium are produced by pulsed laser deposition in an electron cyclotron resonance helium plasma environment. Helium is distributed evenly in the film and a relatively high He/Ti atomic ratio (~20%) is obtained from the proton backscattering spectroscopy. This high concentration of helium leads to a surface blistering which is observed by scanning electron microscopy. Laser repetition rate has little influence on film characters. Substrate bias voltage is also changed for the helium incorporating mechanism study, and this is a helium ion implantation process during the film growth. Choosing suitable substrate bias voltage, one can avoid the damage produced by ion implantation, which is always present in general implantation case.

On the basis of momentum equation on cable, the nonlinear dynamic equation of suspended cable with the support displacement is derived. The nonlinear equations to describe the cable-deck coupled vibration of cable-stayed bridge are deduced and the Mathieu equation(E.Mathieu) is established by the assumed mode method.

18th International Conference on Ion Beam Analysis, Univ Hyderabad, Sch Phys, Hyderabad, INDIA, SEP 23-28, 2007; International audience; The progress achieved in an IAEA Coordinated Research Project (CRP) to improve the cross section data for IBA is reported. The objective of the CRP, started in 2005, is to create a nuclear cross section database for IBA that contains reliable and usable data freely available to the entire IBA community. The major results achieved so far by the CRP participants are discussed. The results include compilation and assessment of the existing cross sections, new experimental data and evaluation of the most wanted cross sections. The experimental results are incorporated into the IBANDL database (www-nds.iaea.org/ibandl/) and evaluated data are presented at the SigmaCalc cross section calculator (www-nds.iaea.org/sigmacalc/). (c) 2007 Elsevier B.V. All rights reserved.

The C-W co-deposition layer prepared by radio frequency magnetron sputtering was investigated to identify the characteristic of the C-W mixed layers in fusion experimental reactors. Layers were characterized by ion beam analysis (IBA), Raman spectra (RS) and scanning electron microscopy (SEM). It was found that D atoms in C-W layers are mainly trapped by the trapping site of C atoms, only a few of them are arrested by W atoms or defects. D concentration in the C-W layers deposited at 5.0Pa with a fixed flow rate ratio QD2/QAr=2.5 was lower than 10% and decreased slightly with increasing temperature. D concentration increased with the gas pressure from zero to 5 Pa and then decreased from 5 Pa to 10 Pa. RS revealed that the crystal structure of the C-W layers became graphite-like with increasing temperature. SEM images showed that the caves disappeared and convex bodies were dotted on the surfaces as the temperature increased.

Helium contents of up to 30at.% are prepared in sputter-deposited Ti films. Isochronal annealing behaviors of helium including the depth profiles and the evolution of helium bubbles in the films at different temperatures are examined by ion beam analysis including Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA), as well as thermal helium desorption spectroscopy (THDS). It is found that the energy spreading induced by structural inhomogeneities in the spectra of RBS and ERDA as well as the increment in the width of spectra occurs, which corresponds to the change of stopping cross-section of helium atoms in the Ti film due to the change of physical-state of helium in the evolution of helium bubble. The ion beam analysis on the helium evolution is consistent with the THDS measurement. Ion beam technique opens interesting possibilities in the characterizing on the growth of helium bubbles.

Based on a lognormal particle size distribution, this paper makes a model analysis on the polydispersity effects on the magnetization behaviour of diluted ferrofluids. Using a modified Langevin relationship for the lognormal dispersion, it first performs reduced calculations without material parameters. From the results, it is extrapolated that for the ferrofluid of lognormal polydispersion, in comparison with the corresponding monodispersion, the saturation magnetization is enhanced higher by the particle size distribution. It also indicates that in an equivalent magnetic field, the lognormally polydispersed ferrofluid is magnetically saturated faster than the corresponding monodispersion. Along the theoretical extrapolations, the polydispersity effects are evaluated for a typical ferrofluid of magnetite, with a dispersity of σ = 0.20. The results indicate that the lognormal polydispersity leads to a slight increase of the saturation magnetization, but a noticeable increase of the speed to reach the saturation value in an equivalent magnetic field.

We present a theoretical calculation finding that a spectrum from ion beam analysis will change at different stopping cross sections. This is more visible at a deeper place in the sample. Helium-contained Ti films annealed at different temperatures are prepared to gain different stopping cross sections whereby the stopping cross section will change with the helium phase states and the pressure of helium bubbles. Then ion beam analysis is used to measure the concentration of helium. It is found that the concentration curve rises greatly after the sample is annealed at 673K which reflects the increasing size of the helium bubble. The results are consistent with that of positron annihilation radiation spectra which are performed by using a changeable energy positron beam.