Thesis (Ph.D.); Submitted to Univ. of California, Davis, CA (US); 17 Sep 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-207378" Gibson, D J. 09/17/2004. Report is also available in paper and microfiche from NTIS.

Diagnosing the temperatures and densities of plasmas is critical to the understanding of a wide variety of phenomena. Everything from equations of state for warm dense matter (WDM) found in Jovian planets and inertial confinement fusion (ICF) to turbulent and dissipative processes in laser-produced plasmas, rely on accurate and precise measurements of temperature and density. This work presents improvements on two distinct techniques for measuring temperatures and densities in plasmas: x-ray Thomson scattering (XRTS), and Langmuir probes (LPs). At the OMEGA laser facility, experiments on warm dense matter were performed by firing lasers at an ablator foil and driving a planar shock into cryogenically cooled liquid deuterium. XRTS in the collective scattering regime was implemented to probe the matter, measuring densities of n_e ~ 4.3 x 10²³ cm^-3, temperatures of T_e ~ 12 eV and ionizations of Z ~ 1.0. Through an extension to XRTS theory for inhomogeneous systems, it was possible to extract an additional parameter, the length scale of the shock, whose value of ? ~ 1.33 nm was consistent with the predicted mean free path, and therefore the thickness of the shock. A unique triple Langmuir probe prototype was designed and tested at the Gregori group's lab at the University of Oxford. This probe was designed for a high temporal resolution of ~ 200 MHz for probing laser-produced shocks. The probes were used to measure the shock formed from ablating carbon rods in an argon gas fill. The probe yielded plasma parameters of n_e ~ 1.0 x 10¹⁷ cm^-3 , and T^e ~ 1.5 eV, consistent with measurements from interferometry and emission spectroscopy.

In this thesis, we present an experimental and numerical study of globularization during reheating of thixocast billet having non-dendritic microstructure. The process of reheating is an important step in the semisolid processing and is essential to control its microstructure and hence its mechanical properties. Material chosen for this study is Aluminum alloy, A356. The primary focus of this study is the heat treatment below eutectic temperature i.e. transformation in solid phase. It is found that during short duration heat treatment, globularization of primary α grains and spheroidization of eutectic Si flakes take place which improves the mechanical properties of semisolid cast products significantly. A prolonged heat treatment is found to degrade the properties of castings since it enhances the porosity and coarsening of Si. The study suggests that a precise heat treatment practice can be designed to improve the semisolid microstructure. A computational model based on Phase field approach has been proposed to study this phenomena. Predictions based on this model are qualitatively compared with corresponding experimental observations. Since eutectics form an important step in multiphase solidification, an attempt has been made to develop an enthalpy based explicit micro-scale model for eutectic solidification. In this preliminary study, growth of adjacent α and β phases in a two dimensional Eulerian framework has been simulated. The model is qualitatively validated with Jackson Hunt theory. Results show expected eutectic growth. This methodology promises significant saving in computational time compared to existing numerical models.

This dissertation examines representations of deep time in nineteenth-century British novels in order to argue that these texts help carve a path for our contemporary definitions of deep time and the Anthropocene. Examining fiction by Charles Dickens, George Eliot, Thomas Hardy, Edward Bulwer-Lytton, H. Rider Haggard, H. G. Wells, and Joseph Conrad, I suggest that these novels participate in the secularization of deep time by transforming the concept of vast spiritual time that had been in use earlier in the nineteenth century into a scientifically-informed model that anticipates our current understandings of deep time. While the concept of geological time emerged in the late-eighteenth century and became widely recognized in the nineteenth, the phrase “deep time” originates in nineteenth-century literature when Thomas Carlyle first used it in a non-scientific context. By studying a wide range of fiction, I demonstrate how nineteenth-century authors employed innovative narrative strategies to convey these potentially inconceivable timescales in non-numerical terms, and thereby make them more accessible to human comprehension. I also challenge conventional distinctions between literary realism and popular romance in the period by analyzing the complementary ways in which both genres of fiction engage with vast temporal scales in their narratives. I develop my argument by examining how these novels use a model of what I call “folding time” to incorporate remote time periods into their texts. Departing from the novel’s linear narrative structure to bring distant historical moments into direct contact with one another, folding time situates human activity in relation to vast pre-and-post-human periods and in doing so acknowledges an age of humans within deep time; in this sense, these novels articulate an early concept of the Anthropocene. By including deep time in the novel’s traditionally individual and familial framework, these authors simultaneously expand the novel’s temporal scope and humanize vast scientific timescales. Further, as these novels illustrate characters’ psychological responses to overwhelming scientific timescales, they reposition deep time in relation to private temporal experience. This study employs an interdisciplinary approach to acknowledge the mutually reciprocal relationship between science and literature in the nineteenth century, and draws on temporality studies, history of science theory, and literary criticism to situate its argument in relation to current critical discussions. I also consider the work of scientists such as Charles Lyell, Charles Darwin, and William Thomson in order to contextualize my novels’ scientific references. By studying nineteenth-century British novels in relation to scientific temporalities, this dissertation recovers an overlooked component of the history of deep time that has had significant and lasting cultural influence given the enduring popularity and wide readership of these texts.

This thesis is about the calculation of a spectral radiance for the K-corona, the continuius spectral part which arise from the Thomson scattering of a solar radiance of free electrons in the corona. Also the Doppler effect is described as it smooth down a solar spectrum (with many absorption lines) to a smoother spectrum of the K-corona. It’s also possible to determine the temperature of free electrons from spectral shape, from which proceeds the method of temperature measurement. NASA intends to use this method on the probe ONSET. Also, temperature definition and its significance are discussed.

High-resolution Thomson scattering system on the COMPASS tokamak provides electron temperature and density profiles in the central and edge plasma region. The spatial resolution in the edge plasma region is optimized for edge transport barrier studies. Formation of characteristic edge profiles (pedestals) is observed during high-confinement mode, i.e. the core electron temperature and density are raised up by the value of pedestal height. Both the electron and density pedestals are well-fitted by a modified hyperbolic tangent (mtanh) function, a five parameter model giving important parameters such as pedestal height and width, necessary for further analysis of the physics behind the transport barrier formation. A fitting technique of the full radial profiles of electron temperature, density and pressure during H-mode is also described. Using the fitting, electron temperature and density on top of pedestal are statistically processed to find a possible threshold for various H-mode regimes.

It is widely accepted that description was used by eighteenth-century writers for the purposes of documentary or ornamentalization. That it was also used to manage the emotions of readers is less often discussed. “Dispassionate Descriptions” corrects this imbalance by attending to the ways in which descriptions in certain scientific and poetic works from the late seventeenth to the late eighteenth centuries were used to dampen the intense emotions that scenes of violence and death tend to inspire, be they sympathy, anger, or love. Writers ranging from William Harvey to James Thomson to John Gabriel Stedman, I argue, taught their readers how to remain dispassionate in the face of suffering and injustice by describing moving bodies and scenes in terms of their physical features alone. By presenting the blood spurting from the wounds of vivisected animals in relation to the regular beat of the heart, a drowning cat in terms of the movements of its head and paws, and the dance of enslaved persons in terms of its irregular beat, the writers I study demonstrated how the disorderly movements of pain or rebellion could be read as expressive of overarching classificatory schemes. Through cultivating dispassion for movements commonly thought to incite passionate responses, these writers worked to maintain the ethical and political status quo. By examining the emotional work descriptions of motion do, “Dispassionate Descriptions” traces an alternative history of how motion from the 1660s to the 1790s was understood outside of the predominant frameworks of mechanism and vitalism. While motion was regarded as inextricable from the literary and scientific discourses of this period, scenes of motion, as I demonstrate, were paradoxically also thought to facilitate emotional retreat. They were thus used by writers to advance a mode of ethics that prized non-interference and the disavowal of moral responsibility.

<p>A specific class of small-scale plasmas (column diameters in a sub-mm to mm range) at rarefied pressures (under 10 Torr) enclosed in glass tubes hold significant interest currently in the scope  of  tunable  plasma  devices.  Specifically,  applications  of  these  plasmas  include  plasma antennas and plasma photonic crystals. Reliable diagnostics are necessary for the development and implementation of these technologies as conventional tools are inadequate in such small-scale plasmas.</p> <p>Coherent microwave scattering in the Thomson regime (TMS) was recently demonstrated for diagnostics of electron number density in miniature free-standing laser-induced plasmas in air under  10  Torr  with  plasma  column  diameters  <  0.5  mm.  However,  measurements  by  TMS diagnostics have never been applied for small-scale plasma objects enclosed within glass tubes. Additionally, TMS measurements were never independently confirmed with a previously verified experimental technique. This work aims to validate results of TMS measurements for small-scale plasma  objects  enclosed  within  glass  tubes  using  the  previously  established  and  well-known hairpin resonator probe. A DC discharge plasma column of fairly large diameter (about 1.5 cm) is used in the experiments to ensure reliable non-intrusive measurements by the hairpin resonator probe.</p> <p>The experiments were conducted in a DC discharge tube with a diameter of 1.5 cm and a length of 7 cm. TMS diagnostics yielded electron number densities of about 5.9×10¹⁰cm^-3, 2.8 ×10¹⁰cm^-3and  1.8 ×10¹⁰cm^-3at  pressures  of  0.2,  0.5  and  2.5  Torr,  respectively.  The corresponding  densities  measured  with  the  hairpin  resonator  probe  were  4.8×10¹⁰cm^-3,  3.8 ×10¹⁰cm^-3 and 2.6 ×10¹⁰cm^-3. Discrepancies between the two techniques were within 30% and can be attributed mainly to inaccuracies in the sheath thickness estimation required the hairpin resonator probe results.</p>

The aim of the present thesis is to improve and optimize a Thomson coil based actuatorfor medium voltage vacuum interrupters. The Thomson coil based actuator’s concept isdiscussed. The thesis presents analytical as well as finite element models of the actuatoralong with a comparison of their results. Several experimental setups have been built forthis degree project and they are described in the thesis. Measurements from these setupsare also compared to simulation results. The thesis concludes by drawing conclusionsfrom the compared results and proposes possible directions for additional work in thenear future. / Målsättningen för denna uppsats är att förbättra och optimera en aktuator för mellanspänningsvakuumbrytare baserad på en Thomsonspole. Aktuatorkonceptet analyserasoch diskuteras. Uppsatsen presenterar analytiska modeller såväl som numeriska modellerför FEM av aktuatorn, samt jämförelser av resultaten från simuleringar gjorda av dessa.Flera experimentuppställningar har byggts under detta examensprojekt och beskrivs idenna uppsatsen. Mätningar från dessa uppställningar jämförs också med resultaten frånsimuleringarna. Uppsatsen drar slutligen slutsatser utifrån resultaten och föreslår möjligavägar för ytterligare arbete på området inom en snar framtid.

京都大学 / 新制・課程博士 / 博士(エネルギー科学) / 甲第24926号 / エネ博第468号 / 新制||エネ||88(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)准教授 南 貴司, 教授 稲垣 滋, 教授 田中 仁 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM