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Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 24, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Physics, Department of Physics, University of Alberta. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 216-225).

A radio-frequency positive-ion source and a fifty-kilovolt linear accelerator were designed and constructed in order to produce sizable quantities of hydrogen, helium, nitrogen, neon, and argon. Plans were then made to equip this ion source with charge-exchange apparatus suitable for charge-exchange cross-sectional measurements. It is the purpose of this paper to present the design of the equipment and to present operational knowledge of the equipment and of ion beams which are producible.

Diante da crescente necessidade de materiais com melhores propriedades para aplicações nos diversos campos da ciência e da tecnologia, a irradiação com feixes iônicos mostra-se como uma importante ferramenta de modicação de materiais. A irradiação de polímeros, em especial, fornece sempre novas perspectivas de aplicabilidade para esses materiais. Diante disso, o presente trabalho tem como objetivo estudar quais são e como ocorrem os processos de modicação de polímeros irradiados com feixes de íons de alta energia. Para essa investigação, amostras de politetrauoroetileno (PTFE) e poli éter éter cetona (PEEK) foram irradiadas no acelerador Unilac do GSI Helmholtzzentrum für Schwerionenforschung GmbH, em Darmstadt, Alemanha, com feixes de íons C, Xe, Au e U, de energia entre 3,6 e 11,4 MeV/u. As amostras foram submetidas à irradiação sob temperatura ambiente e temperatura criogênica (20-40 K). A análise das amostras irradiadas foi realizada através das seguintes técnicas: análise de gases residuais (RGA), espectroscopia de absorção UV-Vis, espectroscopia de absorção no infravermelho com transformada de fourier (FTIR) e difração de raios X (XRD). Observou-se que durante a irradiação do PTFE, os principais processos de modicação são as quebras moleculares e a formação do radical CF3 como grupo terminal e lateral. Além desses, também ocorrem processos de entrelaçamento e formação de estruturas insaturadas, com ligações duplas internas e terminais. Os principais fragmentos voláteis são o CF e o CF3. Durante a irradiação do PEEK observou-se liberação de gás hidrogênio em grande quantidade, como consequência da quebra dos anéis aromáticos do polímero. Algumas reações de recombinação deram origem a formação dos grupos alcino, éster, uorenona e álcool. Além disso o processo de carbonização da amostra foi responsável pelo aumento da condutividade do material. Durante a irradiação sob temperatura criogênica, alguns processos de recombinação nos materiais foram dicultados e grande parte dos elementos voláteis gerados permaneceu congelada no interior do polímero, sendo liberada durante posterior aquecimento até temperatura ambiente. Alguns modelos propostos para explicar efeitos de degradação térmica ou após irradiação com feixe de elétrons foram estendidos com sucesso aos resultados da irradiação com íons pesados e de alta energia. / Nowadays the demand for materials with improved properties for application in different elds of science and technology is constant. Ion beam irradiation is a usual and important tool of modication of materials and polymer irradiation, in particular, has given new perspectives of use for these modied materials. Hence, the aim of this work is the identication of the processes of modication of polymers irradiated with high energy ion beams and how they occur. In this investigation, samples of polytetrauorethylene (PTFE) and poly-ether etherketone (PEEK) were irradiated at the Unilac accelerator at GSI Helmholtzzentrum for Schwerionenforschung GmbH, at Darmstadt, Germany, with C, Xe, Au and U beams with energy between 3.6 and 11.4 MeV/u. The samples were irradiated at room and cryogenic (20-40 K) temperature. The sample analyses were performed through: Residual Gas Analysis (RGA), UV-Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and X Ray Diraction (XRD). Under irradiation, the main processes of modication of PTFE were the chain scissioning and the formation of CF3 terminal and side group. Besides that, cross-linking and new unsaturated structures were also observed, evidenced by the formation of terminal and internal double bonds. CF3 and CF were the main degassed fragments that were observed. During irradiation of PEEK, a great amount of hydrogen gas was liberated as a consequence of the scission in the aromatics rings. Some rearrangement reactions occurred and gave rise to formation of the following groups: alkyne, esther, uorenon and alcohol. Moreover, the process of carbonization in the sample caused an increase in the polymer conductivity. When irradiated under cryo-temperature some recombination processes became more dicult and most of the volatile fragments remained frozen in the polymers. Some degradation models proposed to explain damage effects after thermal and electron beam exposure were sucessfully extended to the obtained results in the case of irradiation with swift heavy ions.

Tip Enhanced Near-field Optical Microscopy (TENOM) is a method for optically imaging at resolutions far below the diffraction limit. This technique requires optical nano-probes with very specialized geometries, in order to obtain large, localized enhancements of the electromagnetic field, which is the driver behind this imaging method. Traditional methods for the fabrication of these nano-probes involve electrochemical etching and subsequent FIB milling. However, this milling process is non-trivial, requiring multiple cuts on each probe. This requires multiple rotations of the probe within the FIB system, which may not be possible in all systems, meaning the sample must be removed from vacuum, rotated by hand and placed back under vacuum. This is time consuming and costly and presents a problem with reproducibility. The method presented here is to replace multiple cuts from a side profile with a small number of cuts from a top down profile. This method uses the inherent imaging characteristics of the FIB, by assigning beam dwell times to specific locations on the sample, through the use of bitmap images. These bitmaps are placed over the sample while imaging and provide a lookup table for the beam while milling. These images are grayscale with the color of each pixel representing the dwell time at that pixel. This technique, combined with grayscale gradients, can provide probes with a symmetric geometry, making the system polarization independent.

The Department of Energy (DOE) Nuclear Energy Research Initiative (NERI) Direct Energy Conversion project has identified the fission fragment magnetic collimator reactor (FFMCR) as a promising direct fission fragment conversion concept. The US DOE NERI Proof-of-Principle Project at Texas A&M is focused on experimental verification of FFMCR operation principles. The purpose of this experiment was to test design parameters of a scaled prototype of a direct energy collector chamber of the FFMCR. The charge collection efficiency was found using a He+ ion beam to be approximately 88% for beam energies ranging from 20 to 80 keV. The 2.4 10^12 ± 10% ohm resistor used in the experiment holds-up under the stress of high voltage to 40 kV. Electric current leakage tests of the charge collection device also indicate that Teflon® is quite sufficient as an insulator for potentials as high as 40 kV. It is suggested that the present work be extended to determine power efficiencies and to achieve results with higher beam energies.

Made available in DSpace on 2014-10-09T12:23:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:02Z (GMT). No. of bitstreams: 1 01035.pdf: 2590190 bytes, checksum: 1d1815b8298ea5a3e4f29d7bf0ea2239 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP

Diante da crescente necessidade de materiais com melhores propriedades para aplicações nos diversos campos da ciência e da tecnologia, a irradiação com feixes iônicos mostra-se como uma importante ferramenta de modicação de materiais. A irradiação de polímeros, em especial, fornece sempre novas perspectivas de aplicabilidade para esses materiais. Diante disso, o presente trabalho tem como objetivo estudar quais são e como ocorrem os processos de modicação de polímeros irradiados com feixes de íons de alta energia. Para essa investigação, amostras de politetrauoroetileno (PTFE) e poli éter éter cetona (PEEK) foram irradiadas no acelerador Unilac do GSI Helmholtzzentrum für Schwerionenforschung GmbH, em Darmstadt, Alemanha, com feixes de íons C, Xe, Au e U, de energia entre 3,6 e 11,4 MeV/u. As amostras foram submetidas à irradiação sob temperatura ambiente e temperatura criogênica (20-40 K). A análise das amostras irradiadas foi realizada através das seguintes técnicas: análise de gases residuais (RGA), espectroscopia de absorção UV-Vis, espectroscopia de absorção no infravermelho com transformada de fourier (FTIR) e difração de raios X (XRD). Observou-se que durante a irradiação do PTFE, os principais processos de modicação são as quebras moleculares e a formação do radical CF3 como grupo terminal e lateral. Além desses, também ocorrem processos de entrelaçamento e formação de estruturas insaturadas, com ligações duplas internas e terminais. Os principais fragmentos voláteis são o CF e o CF3. Durante a irradiação do PEEK observou-se liberação de gás hidrogênio em grande quantidade, como consequência da quebra dos anéis aromáticos do polímero. Algumas reações de recombinação deram origem a formação dos grupos alcino, éster, uorenona e álcool. Além disso o processo de carbonização da amostra foi responsável pelo aumento da condutividade do material. Durante a irradiação sob temperatura criogênica, alguns processos de recombinação nos materiais foram dicultados e grande parte dos elementos voláteis gerados permaneceu congelada no interior do polímero, sendo liberada durante posterior aquecimento até temperatura ambiente. Alguns modelos propostos para explicar efeitos de degradação térmica ou após irradiação com feixe de elétrons foram estendidos com sucesso aos resultados da irradiação com íons pesados e de alta energia. / Nowadays the demand for materials with improved properties for application in different elds of science and technology is constant. Ion beam irradiation is a usual and important tool of modication of materials and polymer irradiation, in particular, has given new perspectives of use for these modied materials. Hence, the aim of this work is the identication of the processes of modication of polymers irradiated with high energy ion beams and how they occur. In this investigation, samples of polytetrauorethylene (PTFE) and poly-ether etherketone (PEEK) were irradiated at the Unilac accelerator at GSI Helmholtzzentrum for Schwerionenforschung GmbH, at Darmstadt, Germany, with C, Xe, Au and U beams with energy between 3.6 and 11.4 MeV/u. The samples were irradiated at room and cryogenic (20-40 K) temperature. The sample analyses were performed through: Residual Gas Analysis (RGA), UV-Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), and X Ray Diraction (XRD). Under irradiation, the main processes of modication of PTFE were the chain scissioning and the formation of CF3 terminal and side group. Besides that, cross-linking and new unsaturated structures were also observed, evidenced by the formation of terminal and internal double bonds. CF3 and CF were the main degassed fragments that were observed. During irradiation of PEEK, a great amount of hydrogen gas was liberated as a consequence of the scission in the aromatics rings. Some rearrangement reactions occurred and gave rise to formation of the following groups: alkyne, esther, uorenon and alcohol. Moreover, the process of carbonization in the sample caused an increase in the polymer conductivity. When irradiated under cryo-temperature some recombination processes became more dicult and most of the volatile fragments remained frozen in the polymers. Some degradation models proposed to explain damage effects after thermal and electron beam exposure were sucessfully extended to the obtained results in the case of irradiation with swift heavy ions.

Made available in DSpace on 2014-10-09T12:23:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:02Z (GMT). No. of bitstreams: 1 01035.pdf: 2590190 bytes, checksum: 1d1815b8298ea5a3e4f29d7bf0ea2239 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP