Tungsten is a candidate plasma facing material for next generation magnetic fusion devices such as ITER and there are major operational and safety issues associated with hydrogen (tritium) retention in plasma facing components. An ion gun was used to simulate plasmamaterial interactions under various conditions in order to study hydrogen retention characteristics of tungsten thus enabling better predictions of hydrogen retention in ITER. Thermal Desorption Spectroscopy (TDS) was used to measure deuterium retention from ion irradiation while modelling of TDS spectra with the Tritium Migration Analysis Program (TMAP) was used to provide information about the trapping mechanisms involved in deuterium retention in tungsten. X-ray Photoelectron Spectroscopy (XPS) and Secondary Ion Mass Spectrometry (SIMS) were used to determine the depth resolved composition of specimens used for irradiation experiments. Carbon and oxygen atoms will be among the most common contaminants within ITER. C and O contamination in polycrystalline tungsten (PCW) specimens even at low levels (~0.1%) was shown to reduce deuterium retention by preventing diffusion of deuterium into the bulk of the specimen. This diffusion barrier was also responsible for the inhibition of blister formation during irradiations at 500 K. These observations may provide possible mitigation techniques for iii problems associated with tritium retention and mechanical damage to plasma facing components caused by hydrogen implantation. Deuterium trapping in PCW and single crystal tungsten (SCW) was studied as a function of ion energy and substrate temperature. Deuterium retention was shown to decrease with decreasing ion energy below 100 eV/D+. Irradiation of tungsten specimens with 10 eV/D+ ions was shown to retain up to an order of magnitude less deuterium than irradiation with 500 eV/D+ ions. Furthermore, the retention mechanism for deuterium was shown to be consistent across the entire energy range studied (10-500 eV) with the shallow penetration depth of low energy ions being the major factor in the reduction in retention. A change in retention mechanism was observed as tungsten temperature during irradiation was increased from 300 to 500 K. Modelling of deuterium retention in 300 and 500 K SCW specimens revealed that two traps, 1.0 and 1.3 eV, are involved in retention for irradiations performed at 300K while a single 2.1 eV trap is present for 500 K irradiations. Experiments suggest that the 2.1 eV trap is created during irradiation of tungsten at 500 K and this process also involves the annihilation of the 1.3 and 1.0 eV traps.

Deuterium retention in two types of polycrystalline tungsten was studied as a function of ion fluence, irradiation temperature and ion energy. Fluence dependence: D retention at 300 K tends to saturate in both Rembar and Plansee PCW. At 500 K, D retention in the Plansee PCW increases with increasing ion fluence, similar to previous results for Rembar tungsten. Even at a fluence of 8×10^25 D+/m2, no sign of saturation was observed. Temperature dependence: D retention in Plansee PCW decreases with increasing irradiation temperature (300 - 500 K). Energy dependence: varying the D+ energy from 100 to 500 eV/D+ plays a minor role in D retention in W, suggesting that D retention depends more on the W structure, irradiation temperature and fluence, rather than on the ion energy when the energy is below the displacement threshold.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 135-153) / Microfiche. / xi, 153 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Michigan, 1935. / Cover title. "By G.A. Cook and J.R. Bates." "Reprinted from the Journal of the American chemical society, 57 ... (1935)."

Thesis (M.S.)--University of Nevada, Reno, 2008. / "May 2007." Includes bibliographical references (leaves 91-96). Online version available on the World Wide Web.

Thesis (Ph.D.)--University of California, Berkeley, 1962. / "UC-34 Physics Distribution" -t.p. "TID-4500 (17th Ed.)" -t.p. Includes bibliographical references (p. 62-63).

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Greg O. Sitz. Vita. Includes bibliographical references.

Universiẗat, Diss., 2004--Bonn.

In this thesis we describe the results of two sets of experiments on spin-polarized atomic hydrogen at temperatures below 1 K using a 115 GHz heterodyne ESR spectrometer. First, we have made measurements of the rates of the two-body recombination processes in spin-polarized atomic hydrogen gas and spin-polarized atomic deuterium gas in a 41 kG field. In the second set of experiments, we examined the ESR absorption line associated with the spin-polarized atomic hydrogen atoms adsorbed on surfaces of liquid helium. In hydrogen, a comparision of the measured recombination rates in 41 kG with the corresponding rates measured in different magnetic fields showed that an additional recombination process is activate for the conditions of these experiments. We demonstrate that this is due to a resonant recombination process via the (v,J) = (14,4) level of molecular hydrogen. In spin-polarized deuterium, we found that the recombination rate are much larger than the analogous rates in hydrogen, and therefore that atomic deuterium gas is much less stable than the hydrogen system under comparable conditions. We report the first observation and study of doubly spin-polarized deuterium, a gas in which both the deuteron and electron spins are aligned. At temperatures near 0.1 K, the absorption line of doubly spin-polarized H atoms changes drastically as a peak appears on both sides of the peak associated with the bulk atoms. We have shown that these new peaks are due to the atoms which are adsorbed onto the surface of the liquid helium film that coats the walls of the microwave cavity. The geometry dependent non-zero average magnetic dipolar field due to aligned spins on a planar surface results in a shift of the position of the ESR absorption lines. The lineshapes of the side peaks are very unusual and are best described as ramp-like. Even after extensive attempts to explain this lineshape, we still do not know what mechanism is responsible. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The uploaded file contains both Part 1 and Part 2 of the work. / An abstract is not provided. / Thesis / Master of Science (MSc)