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Techniques like emission spectroscopy are used to determine and study the proton, helium and hydrogen temperatures in an extremely large-scale microwave plasma source with a very high microwave power. The study of various temperatures, including the Doppler and rotational temperatures clearly shows that the kinetic temperature of the hydrogen atoms is much higher than the background gas temperature.

The thermal and diffusion properties of hot gas around a dc arc discharge under a gravity-free condition are examined by using a jet plane in order to improve the arc production of carbon clusters. The results have shown that carbon clusters including single-walled carbon nanotubes are synthesized around the arc plasma where the He temperature is higher than 1000 K and the large bundles of fatter single-walled carbon nanotubes are produced under the gravity-free condition.

Research describing the formation, evolution and extended defects of bubbles in helium implantation in silicon is presented. In particular the microstructural features of the defects were characterized by means of transmission electron microscopy.

The hydrostaticity of a helium-pressure medium is evaluated with powder x-ray diffraction techniques up to 77 GPa at room temperature. The powder x-ray diffraction method is compared with the ruby fluorescence method in order to get a better understanding of nonhydrostatic stress conditions.

The suppression of thermally induced generation of hole traps in SiO2 layers of Si/SiO2 and poly-Si/SiO2/Si structures by He ambient is analyzed as a function of the gas pressure p. The result suggests that a short-range interaction between the noble gas atoms and the Si/SiO2 network atoms is at the basis of the degradation blockage effect.

Micro-Raman spectroscopy measurements are used for analyzing the temperature distribution of current-carrying, suspended carbon nanotubes in different gas environments near atmospheric pressure. The results have shown that the heat dissipated in the suspended nanotube is removed by its surrounding gas molecules and that the thermal boundary conductance is higher in carbon dioxide than in nitrogen, argon and helium, despite the lower thermal conductivity of carbon dioxide.

Asymmetric double probe theory is developed for collisional plasmas and it is used to microwave-sustained helium plasma jets in order to estimate the plasma parameters at atmospheric pressure avoiding the overestimation of electron temperature.

The fabrication and the performance of the room-temperature reciprocating active magnetic refrigerator prototype are discussed. These prototypes are shown to exhibit extremely high cooling power with a wide temperature span.

The thermoacoustic field is studied quantitatively by the Taconis oscillations with finite amplitude in a helium-filled, quarter-wavelength tube. The significant variation observed in the density, temperature, and entropy diverted the mean values from the respective values in quiescent state.

The studies of large H atom line broadening observed throughout the volume of surface wave generated He-[H.sub.2] and [H.sub.2] microwave plasmas at low pressures are reported. The measurements obtained for the Doppler temperatures corresponding to the H[beta], H[gamma], H[delta] H[epsi] , and H[zeta] line profiles are found to be higher than the rotational temperature of the hydrogen molecular Fulcher-[alpha] band and the Doppler temperature of the 667.1 nm singlet He line.

A theoretical model is presented for equation of state (EOS) of aluminum with helium bubbles and the impact of helium bubbles on shock loading is examined. The bubble mass and concentration has affected the Hugoniot curve and the EOS model has minor significance, indicating that the model is not sensitive to the details of the helium EOS.

Several experimental studies are conducted to explain the spatial densities and the intensity distribution of the enhanced hydrogen emission from low-pressure He plasmas. A new mechanism describing the contribution of helium metastable excited state to the experimental phenomenon is also discussed.

X-ray diffraction measurements as well as electron, optical, and atomic force microscopies are used for analyzing the thermally induced stress relief mechanisms in coimplanted [H.sup.+] and [He.sup.+] ions into (001) Si substrates at moderate energies. Localized exfoliation is described with the help of distinct coarsening processes linking the initially formed gas filled nanosized platelets to crack structures and the delamination behavior is described in terms of unstable crack propagation process triggered at a single nucleation site.

A self-consistent model of charged and neutral particle dynamics which could be applied to atmospheric small-space (200 [mu]m) discharges in helium is detailed. The gas heating, neutral depletion initiation, and electric field reversal observed for microplasmas provide insight into the close interaction between neutral gas and charged species that govern the evolution of the microplasma.

The [N.sub.2]-induced quenching of He-induced intensity enhancement effect is studied in reduced-pressure plasma emission produced by Nd-YAG irradiation on solid zircaloy and porous fossil samples. The quenching effect is explained as a consequence of energy depletion of the He metastable excited state triggered by the Penning ionization process induced by the presence of nitrogen.

The splitting kinetics of [Si.sub.0.8][Ge.sub.0.2] substrates implanted with H-only or sequentially implanted with He and then with H is studied. The extended physical characterization of the implanted and annealed substrates has provided insights into the mechanism of splitting in [Si.sub.0.8][Ge.sub.0.2].

A conventional high resolution transmission electron microscopy was used to study the structural defects induced by He implantation in GaN epilayer at high fluence and elevated temperature. The high resolution images and atomistic simulations provide insight into the nature and structure of defects such as gas-filled rod-shaped cavities in an overpressurized state.

The formation and growth of nanovoids in a C-doped Si layer after [He.sup.+] implantation and thermal annealing are described. The studies have shown how localized strain in epitaxial films can be effectively used to drive nanovoid formation and evolution.

The low frequency noise of magnetic tunnel junctions (MTJs) annealed in a wide temperature range is examined in either in helium or hydrogen environments. The results have shown that the magnetic fluctuators in the MTJs have changed their frequency based on annealing field and temperature and the noise of the MTJs at low frequency is reduced by annealing in high magnetic field.

The effects of helium implantation on silicon substrates based on the direct measurement of the local recombination lifetime are examined by using a differential ac measurement method. The defect distribution and the energy level are used for justifying the behavior of a silicon power diode at different temperatures.

The localization of voids in thin [Si.sub.1-x][Ge.sub.x] layers after [He.sup.+] implantation and thermal annealing is described. The results have shown that the compressive strain in the [Si.sub.1-x][Ge.sub.] layers have induced the nucleation of small cavities and the growth of voids by a mechanism where vacancies are stabilized by He.

[super 3]He-[super 4]He dilution refrigerator is designed to study remnant magnetization of Fe8 high-spin molecules at very low temperatures. This device is used to obtain x-ray magnetic circular dichroism spectra of the molecule at 300 k which is coupled with ligand field multiplet calculations to study the spin and orbit contributions to the magnetization of [Fe.super.3+].

The thermal and electrical characteristics of a heated microcantilever in air and helium over a wide range of pressures are reported. The measurement of thermal conductance around Kn = 1 (where Kn = Knudsen number) could help in the design and analysis of Pirani sensors and other microscale thermal sensors and actuators.

Thermal helium desorption spectrometry (THDS) was used to characterize the helium implantation-induced defects in SiC. All the implanted helium appears to be trapped at room temperature and the intrinsic properties of the materials used in the study seem to play an important role since different behaviors were observed for different samples as well as the surface seems to be a determining parameter for the helium trapping/release behavior.

The low energy He implants in Si are able to induce Cu gettering at both the projected range Rp and half of the projected range Rp/2 region during annealing at relatively high temperatures. A threshold He fluence (0.6 * 10(super 16)

H(super +) was implanted into single-crystal silicon with a dose of 1X10(super 16)/cm(super 2) and an energy of 30 KeV, and then He(super +) was implanted into the same sample with the same dose and an energy of 33 KeV. The results showed that co-implantation of H and He decreases the total implantation dose, with which the surface could exfoliate during annealing.