Helium implantation at room temperature was performed to investigate irradiation hardening of ferritic/martensitic steels. Bulk hardness was extracted from Nix-Gao model using a Berkovich nano-indentor. The correlation between irradiation hardening and helium concentration ranging 500 2000 appm was examined. Nano-hardness increases as a function of helium concentration. The hardening of Fe is s...

Noncatalytic and nonoxidative conversion of methane in a dielectric barrier discharge (DBD) reactor is examined at different temperatures, gas residence times and input powers. In addition, the ratio of methane to helium as a diluant, is changed in the range of 0.6 to 1.8. Results show significant synergetic effects of plasma, temperature and helium on the methane conversion and C2+</s...

We present ’empirical’ models (pressure vs. density) of Saturn’s interior constrained by the gravitational coefficients J2, J4, and J6 for different assumed rotation rates of the planet. The empirical pressure-density profile is interpreted in terms of a hydrogen and helium physical equation of state to deduce the hydrogen to helium ratio in Saturn and to constrain the depth dependence of heliu...

A kinetic rate theory model, which includes the formation of cascade-induced clusters (CIIC), is presented. Comparison of the model to ion irradiation data on vanadium reveals the e€ects of helium generation and cascade-induced interstitial and vacancy clusters on microstructure evolution. The model is based on a simpli®cation of hierarchical rate equations for the clustering of helium bubbles,...

V445 Pup (2000) is a unique object identified as a helium nova. Color indexes during the outburst are consistent with those of free-free emission. We present a free-free emission dominated light curve model of V445 Pup on the basis of the optically thick wind theory. Our light curve fitting shows that (1) the white dwarf (WD) mass is very massive (MWD & 1.35 M⊙), and (2) a half of the accreted ...

The He(n)(+)/He(2)(+) (n ≥ 3) signal ratios in the mass spectra derived from electron impact ionization of pure helium nanodroplets are shown to increase with droplet size, reaching an asymptotic limit at an average droplet size of approximately 50,000 helium atoms. This is explained in terms of a charge hopping model, where on average the positive charge is able to penetrate more deeply into t...

Optical pumping was originally suggested by Kastler [I] in 1950 and since the early 1960's numerous helium magnetometers based upon that technique have been developed. Since then the main evolution has consisted in the advent in 1986 of tunable lasers suitable for helium optical pumping. They led to a renewed interest in helium magnetometry essentially because the magnetometer resolution is exp...

We have measured the He/He and He/Ne ratios and chemical compositions of gases exsolved from deep-sea sediments at two sites (798 and 799) in the Japan Sea. The He/He and He/Ne ratios vary from 0.642 Ratm (where Ratm is the atmospheric He/He ratio of 1.393 × IQr) to 0.840 Ratm, and from 0.41 to 4.5, respectively. Helium in the samples can be explained by the mixing between atmospheric helium di...