To see the other types of publications on this topic, follow the link: Glow.
Dissertations / Theses on the topic 'Glow'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Glow.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
González, Mabel, and Rebeca Rodríguez. "Glow box." Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168143.
Full textAbstract:
TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN ADMINISTRACIÓNGonzález, Mabel, [Parte I], Rodríguez, Rebeca, [Parte II]
La industria de productos de belleza y cuidado personal en Panamá se basa en la importación, distribución y venta (champú, cremas, tratamientos, jabones, aceites, entre otros productos), al igual que presenta un incremento en la creación de productos nacionales por pequeñas empresas. La economía del país se pronostica en un 5.4% siendo la más alta en Latinoamérica y Doing Business califica al país en la posición 79°, favoreciendo a la apertura de nuevos emprendedores y manteniendo el atractivo de la industria. Glow Box es una empresa que ofrece un novedoso sistema de suscripción a productos de cuidado personal no tóxicos a través de la venta online manejada por redes sociales y página web. La presentación de Glow Box es una cajita biodegradable de cartón que contiene cremas corporales, aceites, diferentes tipos de jabones y Shampoo los cuales podrán ser adquiridos por compra individual o por planes de suscripción de 6 a 12 meses. Como factor clave para el éxito de la empresa se resalta el servicio personalizado que ofrece, de acuerdo a los gustos y preferencia de los clientes y brindando un valor agregado con la entrega puerta a puerta. Para la puesta en marcha de este proyecto la empresa requiere realizar una inversión inicial $85,591.34 destinados para la compra de insumos, compra de local, compra de equipo, inversión en publicidad y mercadeo, un sistema contable y logístico para el manejo del inventario. Se ha proyectado que se obtendrá un VAN de $398,687.91 con una TIR de 63% a una tasa de descuento del 16.17% y con un retorno de inversión a 3.5 años.
2
Vachon, Lauren Marie. "Glow: A Novel." Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1374695902.
Full text
3
Mortimer, I. P. "Studies of plasma processes within argon glow discharges by fast flowing glow discharge mass spectrometry." Thesis, Swansea University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638260.
Full textAbstract:
This thesis describes investigations of ionisation processes within analytical argon flow discharges. These were conducted using a novel fast flowing glow discharge ion source previously developed within this laboratory. This consists of a short flow tube with a co-axial cathode glow discharge cell at one end and the ion exit at the other. Investigation of a variety of source parameters showed behaviour inconsistent with ionisation being solely due to Penning ionisation or direct ionisation processes (as is conventionally assumed). This indicates that other previously unconsidered ion-formation pathways also occur within the argon plasma. Various gases were injected into the region of the plasma close to the ion exit. In most cases, the intrinsic plasma ions were replaced by ions originating from the secondary gas. However, when small proportions of hydrogen were added, all of the ions originating from the discharge gas were severely quenched without replacement by ions originating from the hydrogen. The cathode ion abundance was also moderately enhanced. Investigations of this effect indicate that chemi-ionisation processes involving highly excited sates of neutral argon may play a significant role in ion formation within the plasma. The formation of anionic species within argon plasmas was investigated. No anion formation occurred unless the plasma contained electronegative species. Mechanisms are proposed to explain the formation of the anions that were detected. A small electric current is generated within the plasma close to the ion exit cone. The effect of several parameters upon this current have been investigated and the results obtained are consistent with this current originating from field-ionisation of highly excited states of neutral argon close to the ion exit cone.
4
Perks, Christopher A. "Techniques for thermoluminescent glow-curve analysis and the dose response of individual glow peaks in '7LiF." Thesis, University of Sussex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334934.
Full text
5
Chirokov, Alexandre V. Fridman Alexander. "Stability of atmospheric pressure glow discharges /." Philadelphia, Pa. : Drexel University, 2005. http://dspace.library.drexel.edu/handle/1860/657.
Full text
6
Woodcock, Benjamin Kane. "Spectroscopic studies of RF glow discharges." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318464.
Full text
7
Jamali, Arash. "Etching of wood by glow-discharge plasma." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39882.
Full textAbstract:
In this thesis I hypothesize that plasma will etch wood surfaces, produce new cell wall microstructures, and change the surface chemistry of wood because of differential etching of wood’s polymeric constituents. I also examine factors affecting the etching of wood by plasma, and applications of plasma etching for wood processing. Scanning electron and light microscopy and white light confocal profilometry were used to examine etching of wood surfaces. Wet chemical analysis, FTIR and XPS spectroscopy were used to analyze chemical changes at the surface of plasma-treated wood. Experiments were also performed to examine the effect of plasma treatments on the color of blue-stained wood, the morphology of fungal hyphae and the adhesion and performance of coatings on hot-oil modified wood. Exposure of wood to plasma caused etching of wood cell walls and created new surface microstructures. Regions of cell walls that were rich in lignin such as the middle lamella were etched more slowly by plasma. Confocal profilometry of wood exposed to plasma revealed a strong relationship between plasma treatment time and etching of cell walls, and same technique found that lignin pellets were etched more slowly than cellulose pellets. Plasma reduced the levels of carbohydrate at the surface of modified wood, which resulted in a relative increase in lignin content. Plasma treatment improved the effectiveness of hypochlorite bleach at removing blue-stain from wood and it prevented the discoloration of a white acrylic paint on hot-oil modified wood exposed to natural weathering. However, plasma treatment of hot-oil modified wood did not have positive effects on the adhesion and exterior performance of a range of other coatings (mainly semi-transparent stains). I conclude that prolonged exposure to plasma can etch wood cell walls, but cell wall layers that are rich in lignin are degraded more slowly. Plasma etching of wood mainly depends on treatment time and also on the structure and chemical composition of wood. Plasma treatment is an efficient pre-treatment for bleaching of blue-stained wood and reducing the discoloration of white acrylic paint on hot-oil modified wood.
8
Mitchell, D. J. "The positive column argon glow discharge plasma : an excited state gas studied by fast flow glow discharge mass spectrometry." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638206.
Full textAbstract:
This thesis reports studies into the chemical and electrical behaviour of the direct current, fast flowing, argon Glow Discharge plasma using mass spectrometry. Evidence presented suggests that an Excited State model, rather than the conventional Ion/Electron perception describes the Positive Column plasma of the glow discharge. It is proposed that contrary to common belief this cold plasma is a population of stabilised highly excited and potentially long lived, argon Rydberg atoms rather than an ionised medium. Studies involving the titration of small amounts of H2, Ar, He and CC14 into the discharge, and the variation of the macroscopic properties of the plasma, were undertaken to examine the chemical and electrical and properties of the plasma. These results, in addition to those obtained by double probe studies, were inconsistent with processes pertaining to the Ion/Electron model of the plasma. The macroscopic properties of the discharge varied included gas glow rate, pressure, residence time, discharge voltage and current, sampling cone bias (positive and negative voltages). The effects of changing these parameters on the voltage distribution across the plasma was also examined. The results indicated that contrary to conventional 'free' ion/electron theory the discharge is sustained by the action of highly excited neutral argon states existing as a continuum and chemically distinct resonances. Detected ions were concluded to originate from outside the plasma by chemi-, auto-, or field-ionisation. Electric current flow across the plasma is proposed to be a facet of discharge gas excitation rather than ionisation with charge transfer between excited atoms providing the means of electron conduction rather than diffusive random motion. A simple model of the electrical properties of the discharge is presented which derives theoretically the experimental observation of a direct, linear, proportionality between the resistance of the discharge and reciprocal discharge current.
9
Jayaraman, Balaji. "Computational modeling of glow discharge-induced fluid dynamics." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0015702.
Full text
10
Dahhan, A. K. "Real-time microwave holography using glow discharge detectors." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356739.
Full text
11
Huppert, Gilbert Lee. "Two-dimensional simulation of radio-frequency glow discharges." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40574.
Full text
12
Merchant, Christopher Ali 1975. "Active noise control using glow discharge plasma panels." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/82198.
Full text
13
Deng, Xu-Tao. "Stable atmospheric glow discharges : computational study and applications." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/36172.
Full textAbstract:
This thesis describes a study of stable atmospheric pressure glow discharges through both a PC-based numerical simulation of their dynamics and exploratory experiments for establishing their decontamination efficacy. The numerical work is based on a one-dimensional fluid model with a commonly adopted hydrodynamic approximation that assumes electron equilibrium with the local electric field. Two gas systems are considered, namely pure helium and helium-nitrogen mixture, and our simulation results agree well with relevant experimental data. Also the numerical study establishes a specific frequency range within which stable helium atmospheric pressure dielectric-barrier glow discharges can be generated, and unravels two distinct plasma disruption mechanisms when the plasma excitation is outside the above mentioned frequency range. Further explored is possible plasma power saving that can be achieved by means of pulsed excitation. It is shown that significant power saving of up to 40% can be achieved by a combination of wave-shaping and pulse-width reduction. Finally through preliminary exploratory experiments, it is shown that atmospheric pressure glow discharge is biologically lethal to food-borne microorganisms and when further developed can form the basis for a novel food decontamination technology.
14
Shi, Jianjun. "Experimental and theoretical studies of atmospheric glow discharges." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7982.
Full textAbstract:
This thesis presents the experimental and theoretical studies of nonthermal and stable atmospheric-pressure glow discharges. With the excitation frequency in the kilohertz range, a uniform and stable glow discharge has been successfully produced in atmospheric helium without the usually indispensable dielectric barrier. For this barrier-free cold atmospheric discharge, there are two discharge events occurring, respectively, in the voltage-rising and the voltage-falling phases, and in general they compete with each other. This distinct feature is illustrated through a detailed fluid simulation. For direct current atmospheric glow discharges, their cathode fall region is shown to depend critically on the discharge current density. For atmospheric glow discharges excited at 13.56 MHz on the other hand, we present observations that after gas breakdown, the discharge evolves from the normal glow mode to the abnormal glow mode and then through the recovery mode back to the normal glow mode. The operation modes, namely the a mode and the y mode, in radio-frequency atmospheric glow discharges are investigated with a one-dimensional, self-consistent continuum model. This model is evaluated by comparing our numerical results with experimental data and other simulation results in literature. It is shown that gas ionization is volumetric in the a mode and localized in the boundary region between the sheath and the bulk plasma in the y mode. The stable operation regime in the a mode is found to have a positive differential conductivity, and can be expanded to higher discharge current density without compensating plasma reactivity by increasing the excitation frequency. Furthermore this plasma stability-reactivity balance is also studied for radio-frequency atmospheric glow microdischarges.
15
Smith, David Murray. "Diode laser spectroscopy of silane plasmas." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259622.
Full text
16
Smith, Robert Vanderhoof. "A study of the glow discharge supersonic jet interface." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/26906.
Full text
17
Queiroz, Joelma Costa de Lima. "Developing groundwater glow and recharge models for chalk catchments." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508936.
Full text
18
Gogolides, Evangelos. "Self-consistent continuum modeling of radio-frequency glow discharges." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14284.
Full text
19
Chen, Linghao. "Surface layer evolution in glow discharge optical emission spectroscopy." Thesis, Sheffield Hallam University, 2005. http://shura.shu.ac.uk/19452/.
Full textAbstract:
Glow discharge optical emission spectroscopy (GDOES) is a modem analytical technique for the analysis of the chemical composition of bulk materials and the depth profiling of multi-layer structures. Most research in the use of GDOES has concentrated on developing accurate methodologies for quantitative analysis and depth profiling. However, this thesis presents a study on various aspects of surface layer evolution under argon ion etching in GDOES. The GDOES technique relies on the ion bombardment of sample surfaces which removes material from the surface, layer by layer, on the atomic scale. During the surface layer evolution, the ion bombardment causes different surface micro-textures and preferential sputtering in individual crystallites, which can cause degradation of depth resolution in GDOES depth profiling. Experimental results using pure iron specimens in this study show a correlation between textures induced by GDOES sputtering and the sputtering rate, and a difference in the sputtering rate for crystallites with different crystal orientations. In studying ion bombardment by GDOES in semiconductors, a novel pitting morphology on the surface of a carbon-coated silicon wafer was observed and characterised in detail. This may have a potential application in the fabrication of micro-lens arrays. The generation and development of the pits were investigated, which are believed to be dependent upon the different sputtering rates between the film and the substrate. Geometric features of the pits were obtained using atomic force microscope (AFM) and the sphere-like surface of the pit was confirmed. The experimental work in this study also shows that the Grimm source in GDOES is a powerful etching tool. Eroded surfaces of metal specimens with little damage to the crystallites and phase structures were obtained by GDOES etching. The method was found to be an ideal process for specimen preparation for electron back-scattered diffraction (EBSD). The GDOES-etched surface of single crystal copper showed that the damaged layer formed by mechanical polishing using 6 micron diamond paste was about 1-2 pm and was removed after only a few tens of seconds of GDOES etching. GDOES etching was also applied to an investigation of internal oxides in carburised steels. The eroded surfaces provided plan views of the morphologies of internal oxides of carburised steels by scanning electron microscopy (SEM) images. Results of energy dispersive spectrometer (EDS)/SEM elemental mappings of different layers of the steels were in good agreement with GDOES depth profiles, which revealed that the elements Cr, Mn and Si were involved in the oxides. The last section of the thesis is about hydrogen detection in GDOES. The study includes a detailed analysis of: hydrogen contamination in GDOES, the hydrogen detection status of GDOES, the sample matrix effects on hydrogen detection and hydrogen effects on elemental concentrations in GDOES measurements. The experiments have confirmed that water vapour is the main source of the hydrogen contamination. When the GDOES system has stabilised, GDOES could be employed to differentiate specimens containing different concentrations of hydrogen. The experiments also showed that different hydrogen intensities could have resulted from different matrices even when the specimens were believed to contain no hydrogen. A possible explanation could be that variations of the y-electron ejection from different matrices and different sputtered atoms in the glow discharge, which altered the plasma and the energy distribution in the glow region, resulted in the variation of the excitation of the hydrogen atoms in the source. However, there are still some results in the matrix effects which could not be explained. The experiments concerning the consequence of hydrogen effects on apparent elemental concentrations in GDOES measurements were also undertaken using two steel standards. The results indicated that the hydrogen in the source has a negative effect on the signal from most of the metal elements in the specimens, and a positive effect on the non-metal and semiconductor elements.
20
Lewis, Cris Lee. "Characterization and applications of pulsed millisecond glow discharge sources." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1531.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xv, 161 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 153-157).
21
Rozban, Daniel. "Development of a THz imaging system using Glow discharge detector /." [Beer Sheva] : Ben Gurion University of the Negev, 2009. http://aranne5.lib.ad.bgu.ac.il/yaatz/RozbanDaniel.pdf.
Full text
22
Seneza, Cleophace. "Thermoluminescence of secondary glow peaks in carbon-doped aluminium oxide." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013053.
Full textAbstract:
Carbon-doped aluminium oxide, α-Al₂O₃ : C, is a highly sensitive luminescence dosimeter. The high sensitivity of α-Al₂O₃ : C has been attributed to large concentrations of oxygen vacancies, F and F⁺ centres, induced in the material during its preparation. The material is prepared in a highly reducing atmosphere in the presence of carbon. In the luminescence process, electrons are trapped in F-centre defects as a result of irradiation of the material. Thermal or optical release of trapped electrons leads to emission of light, thermoluminescence (TL) or optically stimulated light (OSL) respectively. The thermoluminescence technique is used to study point defects involved in luminescence of α-Al₂O₃ : C. A glow curve of α-Al₂O₃ : C, generally, shows three peaks; the main dosimetric peak of high intensity (peak II) and two other peaks of lower intensity called secondary glow peaks (peaks I and III). The overall aim of our work was to study the TL mechanisms responsible for secondary glow peaks in α-Al₂O₃ : C. The dynamics of charge movement between centres during the TL process was studied. The phototransferred thermoluminescence (PTTL) from secondary glow peaks was also studied. The kinetic analysis of TL from secondary peaks has shown that the activation energy of peak I is 0.7 eV and that of peak III, 1.2 eV. The frequency factor, the frequency at which an electron attempts to escape a trap, was found near the range of the Debye vibration frequency. Values of the activation energy are consistent within a variety of methods used. The two peaks follow first order kinetics as confirmed by the TM-Tstop method. A linear dependence of TL from peak I on dose is observed at various doses from 0.5 to 2.5 Gy. The peak position for peak I was also independent on dose, further confirmation that peak I is of first order kinetics. Peak I suffers from thermal fading with storage with a half-life of about 120 s. The dependence of TL intensity for peak I increased as a function of heating rate from 0.2 to 6ºCs⁻¹. In contrast to the TL intensity for peak I, the intensity of TL for peak III decreases with an increase of heating rate from 0.2 to 6ºCs⁻¹. This is evidence of thermal quenching for peak III. Parameters W = 1.48 ± 0:10 eV and C = 4 x 10¹³ of thermal quenching were calculated from peak III intensities at different heating rates. Thermal cleaning of peak III and the glow curve deconvolution methods confirmed that the main peak is actually overlapped by a small peak (labeled peak IIA). The kinetic analysis of peak IIA showed that it is of first order kinetics and that its activation energy is 1:0 eV. In addition, the peak IIA is affected by thermal quenching. Another secondary peak appears at 422ºC (peak IV). However, the kinetic analysis of TL from peak IV was not studied because its intensity is not well defined. A heating rate of 0.4ºCs⁻¹ was used after a dose of 3 Gy in kinetic analysis of peaks IIA and III. The study of the PTTL showed that peaks I and II were regenerated under PTTL but peak III was not. Various effects of the PTTL for peaks I and II for different preheating temperatures in different samples were observed. The effect of annealing at 900ºC for 15 minutes between measurements following each illumination time was studied. The effect of dose on secondary peaks was also studied in this work. The kinetic analysis of the PTTL intensity for peak I showed that its activation energy is 0.7 eV, consistent with the activation energy of the normal TL for peak I. The PTTL intensity from peak I fades rapidly with storage compared with the thermal fading from peak I of the normal TL. The PTTL intensity for peak I decreases as a function of heating rate. This decrease was attributed to thermal quenching. Thermal quenching was not observed in the case of the normal TL intensity. The cause of this contrast requires further study.
23
Dash, N. A. "Fast flow glow discharge studies of a Rydberg gas plasma." Thesis, Swansea University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636354.
Full textAbstract:
This thesis reports novel investigations into the fundamental characteristics of direct current, fast flowing, argon glow discharge plasmas. The results presented provide further evidence for a neutral excited state plasma as opposed to the conventional free ion-electron theory that pervades glow discharge literature. Also described are the design, development and characterisation of a third generation Fast Flowing Glow Discharge (FFGD) ion source for fundamental studies. Fundamental studies involved the titration of small amounts of He, Ar, H2, CH4, SF6, NO, NO2, C4H10 and CCI4 into both a flowing plasma and the full discharge. The chemical, electrical and charge distribution properties of the plasma were monitored simultaneously over the course of reagent introduction. The results were wholly inconsistent with the processes thought to predominate in the ion-electron model of the plasma. The quenching of Rydberg states by the reagent gases was also empirically assessed. The development of the third generation ion source involved a study of the variation of the macroscopic properties of the discharge including the residence time, discharge voltage/current and sampling cone bias. Kinetic energy analysis was also performed on ions emerging from the plasma. The formation of anionic species within the plasma and discharge were investigated. No anion formation was observed unless electronegative species were introduced. In addition a number of source adaptations were designed, tested and modelled. The work in this thesis provides further evidence that the flowing glow discharge is maintained by Rydberg states in both an extended plasmas and a full discharge system. The detected ions were shown to originate from the plasma boundary by chemi-, auto- or field-ionisation. The work supports a previous hypothesis that charge transfer between highly excited Rydberg states maintains the electric current flow across the plasmas and discharge.
24
Webb, MR, FJ Andrade, G. Games, R. McCrindle, and GM Hieftje. "Spectroscopic and electrical studies of a solution-cathode glow discharge." Journal of Analytical Atomic Spectrometry, 2005. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000982.
Full textAbstract:
A glow discharge using a solution as the cathode was investigated to add to the understanding of the
operating mechanism and characteristics of such systems. The intensities and vertical distributions of
emission from several analytes and background species were observed and compared with the vertical
distribution of Fe excitation and OH rotational temperatures, as well as to electrical characteristics. The
effects of the discharge gap size, the pH and conductivity of the solution, the applied current and the
solution flow rate on these distributions were also studied. Detection limits for this system were found to be
comparable to those of similar systems and mostly in range of tens of parts per billion.
25
Pedder-Smith, Rachel. "The glow of significance : narrating stories using natural history specimens." Thesis, Royal College of Art, 2011. http://researchonline.rca.ac.uk/430/.
Full textAbstract:
The subject of this project is natural history specimens and the exploration of their qualities in visual artwork. The first part is a 533cm watercolour painting composed of an image of at least one specimen (or part thereof) to represent each flowering plant family, of which there are 505. The ‘Herbarium Specimen Painting’ was created using dried plant specimens from the herbarium collection at the Royal Botanic Gardens, Kew. The plant families are painted in systematic order following one of the recently developed DNA classification systems. The painting was produced with scientific rigor and under the constant supervision of Kew botanists. It aims not only to illustrate the chosen classification system but to explore the aesthetic beauty of herbarium specimens and celebrate many of the incredible and varied narratives contained within the Kew collection. The second element of this thesis constructs a context for the above artwork among similar projects. Natural history institutions worldwide were contacted for information about artists using natural history collections to produce art with a strong narrative element that ‘discussed’ the notion of the specimen. These artists were then contacted and many interviewed. In parallel, the literature review concentrated on theories developed in the field of material culture where the human relationships between groups of objects are analysed. These theories proved fundamental and on occasion inspirational in uncovering deeper meanings and narrative possibilities. The concluding section of this research discusses whether the findings of this project, which uses and develops material culture theory can contribute to that field of research. It analyses the possibility that specimen-based artwork can benefit science and/or help revitalise museum collections, and comments on whether institutions can improve the public communicability of the objects in their care by treating them as a potential source for new art.
26
Wang, Liang. "Analysis of Galvanized Steel Plates Using Glow Discharge-Atomic Emission Spectrometry." TopSCHOLAR®, 1999. http://digitalcommons.wku.edu/theses/762.
Full textAbstract:
Combining an intense emission source and a high-speed sputtering source in one, glow discharge atomic emission spectrometer (GD-AES) provides an efficient technique for analyzing surfaces, coatings and bulk solids. The purpose of our work is to explore the optimum lamp operation parameters of SA-2000 for analysis of galvanized steel plate and to investigate the method for qualitatively and quantitatively analyzing the zinc coating. Under the optimum experimental conditions found in our study, which are current of 19-21 mA; voltage of 900-1200 V; pressure 2.0-2.5 torr, the calibration curve is constructed, so that specific zinc concentration can be assign to the exact depth position in the sample. Several galvanized steel plate samples are tested and the thickness of coating and distribution of zinc in different depth of the coating are calculated on the basis of calibration curve. The above results are further analyzed to prove the reproducibility of the proposed method.
27
Léveillé, Valérie 1977. "A miniature atmospheric pressure glow discharge torch for localized biomedical applications /." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102676.
Full textAbstract:
This thesis presents the design and characterization of a novel pulsed miniature capacitively-coupled Atmospheric Pressure Glow Discharge Torch (APGD- t) aimed at localized biomedical applications. Amplitude modulation of the 13.56 MHz carrier signal allows to continuously vary the power level applied to the APGD-t. Typically, the APGD-t produces a plasma jet with a 150-500 μm diameter and ≈2.5 mm length. Helium (He) is the plasma-forming gas with a flow rate ranging from 0.5 to 1.5 slm. The use of a small capillary electrode enhances the electric field, lowering the breakdown voltage (typically 220 Vpk-to-0) and allows the injection of small amounts (0-50 sccm) of a source of reactive species (O2) downstream of the plasma-forming region, in the plasma afterglow. The O2 is electronically dissociated in the plasma afterglow to create atomic oxygen (O) with no effect on the electrical properties. A ratio of 0.3% v/v, O2/He generates a maximum in O production.Careful electrical probe measurements and circuit analyses reveal the strong effect of commercial passive voltage probes on the total load impedance of the APGD-t circuit. The larger the probe capacitance and cable length, the larger the component of the phase angle between the load voltage and circuit current signals induced by the probe. The calibration of the phase angles induced by the voltage probes allows to estimate that a resistive power of ~0.24-1 W is dissipated in the APGD- t under nominal operating conditions.
The gas kinetic and atomic He excitation temperatures, and the electron density near the APGD-t nozzle exit are estimated at ≈323 K, ≈1914 K and ≈1011 cm-3, respectively. This confirms that the APGD-t plasma jet near the nozzle exit is in a non-thermal equilibrium state. The emission spectroscopy study reveals the entrainment of air molecules (N2, O2 and H2O) in the plasma jet, and that their excitation by the plasma creates new reactive species (O and OH). A preliminary survey of the chemical reactions taking place in the plasma afterglow reveals that metastable He as well as OH, O, O2(a1Δg), O2(b1Σg+), N2, N2+ and O3 are plasma species that can reach and react with organic or biological surfaces located a few mm downstream of the APGD-t nozzle exit. This thesis demonstrates that the APGD-t is a promising tool for localized biomedical applications.
28
Pichilingi, M. "Glow discharge mass spectrometry : source design and development, applications and theory." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638528.
Full textAbstract:
Much of the work in this thesis was carried out with a strong regard for the interests of the collaborative body, British Steel Technical. Hence, an original review of the techniques employed for analysis within the steel industry are provided, which concludes outlining the potential role of GDMS. A new ion source was designed and constructed for coupling to an existing high resolution mass spectrometer for the analysis of flat samples by GDMS. Details of the extensive work carried out to improve and characterise this source are given. A new commercial instrument, the VG Gloquad, came onto the market during the course of this Ph.D. This instrument was used for comparison with our system and an evaluation of GDMS for analysis within the steel industry was performed. Results are given which demonstrate the potential of quadrupole-based GDMS for depth profiling. However, recommendations are given which could improve the performance of both state-of-the-art GDMS and GDOES. In addition, the theory of cathodic sputtering has been re-examined and an expression has been developed which describes the transport of sputtered material within the glow discharge. This predicts the inverse pressure dependence of glow discharge sputter yield observed, as well as its unexpected independence from the diffusion coefficient. It is also demonstrated that glow discharge sputter yield correlates well with the accepted theory for primary sputtering, as is also predicted by our expression, for both different discharge gases and sample targets. Finally, it is proposed that in the 1-3 Torr pressure range, typical for mass spectrometry, sputtering is due to bombardment by fast discharge gas atoms rather than discharge gas ions, as is the commonly held view. It is also being suggested that there is a change in mechanism at higher pressures to sputtering by ions of the sample itself.
29
Liu, Dawei. "Experimental and numerical study of radio frequency atmospheric pressure glow discharges." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/13987.
Full textAbstract:
Radio frequency (rf) atmospheric pressure glow discharges (APGDs) have received growing attention for their exciting scope of new science and their immense potential for widespread applications. While geometrically similar to conventional low-pressure discharges used in the semiconductor industry for decades, rf APGDs present new physics that require investigation. This thesis presents an experimental and computational study of helium rfAPGDs aimed at making a contribution to the current understanding of these discharges and enabling their optimization for different applications. The timely interest and significance of this work is highlighted by the publication of different parts of this thesis in 10 peer-reviewed international journals. Starting with the electron trapping in rf APGDs, the thesis looks into the electron heating mechanism responsible for sustaining the discharges, the influence of the rf excitation frequency on the discharge characteristics, the role of impurities in the discharge chemistry as well as the evolution of the discharge as the size is reduced down to microplasma dimensions. The findings of this research are based on the synergistic use of electrical measurements, optical diagnostics and self-developed computational models. With the knowledge gained from this thesis, rf-APGDs can be readily used for a wide-range of applications including biological decontaminations, nanostructure fabrication and portable gas analyzers.
30
Carman, R. J. "DC glow discharge electron guns for the excitation of rare gases." Thesis, University of St Andrews, 1986. http://hdl.handle.net/10023/14165.
Full textAbstract:
Glow discharge electron guns are used to generate continuous electron beams at 0.5keV-3.0keV in the intermediate range of gas pressures (0.1mb-10.0mb). Cathodes incorporating internal cavities are used to generate distinct electron beam filaments in both Helium and Argon. The formation of such beam filaments has been investigated using a number of different cathode types, and criteria for the production of stable electron beams are established. The production of an electron beam in a glow discharge is largely determined by the motion of electrons in the Cathode dark space sheath region next to the cathode, and other discharge processes in this region. A theoretical model has been developed to simulate electron motion in the sheath region, and in the Negative glow plasma region, of a Helium discharge with a Cathode fall of between 150V and 1000V. It is shown that the electron flux at the 'sheath/Negative glow boundary becomes increasingly monoenergetic as the Cathode fall rises to 1000V. The results are also compared with experimental spatial emission profiles of the glow in the Cathode dark space and Negative glow regions of a helium discharge. In particular, properties of the Cathode glow region in the sheath are discussed. Aspects of the theoretical model and results from the experimental measurements are also used to discuss discharge processes in the sheath region of cathodes incorporating internal cavities, and mechanisms leading to the formation of the electron beam filaments. The production of fast electrons in a glow discharge has a number of applications, including the excitation of gases leading to laser action. Aspects relating to the excitation of high lying energy states in gases, corresponding to known laser transitions, are discussed. It is shown that the production of helium ions, which are responsible for the excitation of metal atoms via asymmetric charge transfer in metal ion lasers, is theoretically more efficient in an electron beam discharge. The results are compared with the theoretical ion production rates in Hollow cathode discharges, and high-voltage Hollow cathode devices. Several electrode geometries using multiple arrays of electron gun cathodes have been developed. Investigations of an electron beam excited argon plasma suggest that Ar II excited states are pumped directly by single electron impacts, even at very low current densities (~10-3 A cm-2). From previous calculations using the 'sudden perturbation' approximation, those ion states known to have large cross-sections for direct electron impact excitation (3p44p2P) appear to be favourably pumped in the electron beam plasma.
31
Phillips, Hugh Alan. "Spectroscopic investigations of glow discharges and the emissions of nonmetallic elements in the argon inductively coupled plasma." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184400.
Full textAbstract:
Spectroscopic investigations have been carried out on hollow cathode discharges adapted from laser technology for use as a spectroscopic light source and the argon inductively coupled plasma (ICP) as an excitation source for nonmetal emission. High and low voltage aluminum and copper hollow cathode discharges were studied as a source of ionic and resonant atomic metal emission. The high voltage versions achieve strongly positive current-voltage behavior through utilization of the obstructed discharge phenomenon. The current-pressure-intensity-voltage relationships for low and high voltage copper hollow cathode discharges were studied with the inert gases He, Ne, Ar, Kr, and Xe. The intensity for copper resonant atomic emission with the fill gases Ar, Kr, and Xe improved relative to neon in the high voltage lamp when compared to the low voltage lamp. Absorption measurements through the cathode bore show the ground state atom density to increase with the atomic weight of the fill gas at any given level of intensity, at the fill gas pressure yielding highest resonant atomic copper emission. The estimated ion/atom intensity ratio is increased with fill gases which have metastable or ionization energies greater than the excitation energy of the ion transition. A copper hollow cathode lamp incorporating a short positive column discharge in front of the cathode opening was investigated for its lineshape as measured spectroscopically and by its atomic absorption sensitivity. Incorporation of this positive column allowed higher intensities to be obtained at the same line quality as a commercial hollow cathode lamp. An enlarged cathode volume also improves the lineshape at a given intensity. Inductively coupled plasma spectra for the elements C, O, N, Cl, P, S, and Br were obtained in the vacuum ultraviolet utilizing a vacuum polychromator and SWR film. The detection limit for injected O₂ and N₂ detected electronically by the VUV emissions is 1.3 and 0.9 micrograms respectively with this system. A VUV filter photometer was utilized for oxygen and phosphorus analysis. The detection limit for injected oxygen was 1 microgram with this photometer; the detection limit for phosphorus as inorganic phosphate in aqueous solution is 10⁻³ M. The bandpass of the photometer limits its selectivity.
32
Baker, Claire. "Australian glow-worms (Diptera: Keroplatidae: Arachnocampa spp.) : disbtribution, diversity, identity and management /." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18287.pdf.
Full text
33
Efimova, Varvara. "Study in analytical glow discharge spectrometry and its application in materials science." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-75317.
Full textAbstract:
Glow Discharge Optical Emission Spectrometry (GD OES) has proved to be a versatile analytical technique for the direct analysis of solid samples. The application of a pulsed power supply to the glow discharge (GD) has a number of advantages in comparison with a continuous one and thereby broadens the analytical potential of the GD. However, because the pulsed GD (PGD) is a relatively new operation mode, the pulsing and plasma parameters as well as their influence on the analytical performance of the GD are not yet comprehensively studied. The aim of this dissertation consists in the investigation of the PGD features, which are crucial for both understanding the discharge plasma processes and analytical applications. The influence of the pulsing parameters on the PGD is ascertained and compared for direct current (dc) and radio frequency (rf) discharges. In the research attention is firstly paid on the electrical parameters of PGD, then on the sputtered crater shapes, sputtering rates and finally on the light emission. It is found that the sputtered crater shape is strongly affected by the duration of the applied pulses even when the duty cycle is fixed. The pulse length influences the intensity of the light emission as well (at constant duty cycle). Moreover this influence is different for emission lines of atoms and ions in the plasma. This phenomenon can be seen at the comparison of atomic and ionic lines of different elements. The voltage–current plots of the PGD are found to indicate heating of the discharge gas when operating at high duty cycles. Using this feature a new method for the estimation of the discharge gas temperature from the voltage-current characteristics of the PGD is developed. The calculated temperature values are compared with another temperature measurement technique. Different temperature estimation procedures have shown that the discharge gas temperature can be reduced by around 100 K when PGD is applied. The temperature measurements have also confirmed that the gas heating can be adjusted by variation of the pulsing parameters. The effect of sputtering on the Cu(In,Ga)Se2 (CIGSe) layer surface of the solar cells is described for the first time. SEM investigations of the CIGSe layer of the solar cells have shown that sputter induced effects can be reduced by variation of the pulsing parameters. With regard to the question whether dc and rf pulsed discharges behave similarly: nearly all phenomena found with dc discharges also appear in the rf case. Hence it is concluded that the pulsed rf and dc discharges are very similar in terms of the electrical properties, sputtered crater formation, light emission and temperature. It is concluded that matrix specific, as well as matrix independent quantification principles and the intensity correction developed by Arne Bengtson can be applied for the pulsed mode, if special conditions are fulfilled. CIGSe solar cell samples and thin layered electrode metallizations of SAW devices are measured and quantified with application of PGD. The proposed quantification procedures are performed at commercial GD OES devices and can be used for the analysis with application of pulsed rf discharge. The studies of the PGD performed in this dissertation are relevant for the application of the GD OES analysis in materials science. During the collaborative work with Helmholtz-Zentrum Berlin für Materialien und Energie and with the research group of Dr. Thomas Gemming at IFW Dresden the optimized pulsed GD OES measurements could be successfully applied at the investigation of thin film solar cells with CIGSe light absorbing layer and electrode matallizations of SAW devices. In case of solar cell samples pulsed GD OES depth profiling along with SIMS measurements reveal the role of the Al2O3 barrier layer in high efficiency solar cells consisting of a CIGSe/Mo/Al2O3/steel substrate layer stack (the barrier layer is to prevent the Fe diffusion into the CIGSe). The features of the CIGSe films growth are studied with help of pulsed GD OES and in situ synchrotron XRD measurements. The diffusion coefficient of Zn into the CuInS2 layer is determined for the first time from the measured GD OES depth profiles of the corresponding solar cell samples. In case of SAW samples, pulsed GD OES measurements helped to evaluate the different SAW electrode preparation procedures and to select the most suitable one. In addition pulsed GD OES depth profiling along with XPS, TEM-EDX and electrode lifetime measurements indicate the possible mechanism of power durability and lifetime improvement of the SAW devices when a small amount of Al is added to the Cu-based electrodesDie optische Glimmentladungsspektroskopie (engl. Glow Discharge Optical Emission Spectrometry - GD OES) hat sich als eine vielfältige und schnelle Methode für die direkte Analyse von festen Materialien erwiesen. Die Anwendung von gepulsten Glimmentladungen (GD) bietet eine Reihe von Vorteilen im Vergleich zu einer kontinuierlichen Entladung und erweitert dadurch das analytische Potential der Methode. Die praktische Anwendung von gepulsten GD erfordert jedoch ein tiefes Verständnis der Prozesse, die in der Entladung und im elektrischen System ablaufen. Der Einfluss der Puls- und Plasmaparameter auf die analytische Leistung der gepulsten GD ist bislang noch nicht umfassend erforscht worden. Die Zielstellung dieser Arbeit besteht in der Untersuchung der Eigenschaften der gepulsten GD, welche von besonderer Bedeutung sowohl für das Verständnis des Entladungsprozesses als auch für analytische Anwendungen ist. Die Auswirkungen der Pulsparameter auf die gepulste GD wurde für den Gleichstrom-(DC) und Hochfrequenz- (HF) Modus untersucht und verglichen. Die Reihenfolge der Untersuchungen wurde in dieser Arbeit wie folgt gewählt: elektrische Parameter, Sputterkraterformen, Sputterraten und Lichtemission. Die Form des Sputterkraters korreliert stark mit der Pulsdauer, selbst wenn das Tastverhältnis konstant ist. Die Pulsdauer beeinflusst nicht nur die Kraterform, sondern auch die Intensität der Emissionslinien (bei konstantem Tastverhältnis). Darüber hinaus ist dieser Einfluss unterschiedlich für Atome und Ionen. Dieses Verhalten wurde an mehreren Emissionslinien (atomar bzw. ionisch) nachgewiesen. Aus der Analyse der U-I-Kennlinien der gepulsten GD ergab sich, dass es zu einer Erhitzung des Plasmas bei höherem Tastverhältnis kommt. Dieser Effekt wurde zur Bestimmung der Plasma-Gastemperatur ausgenutzt. Die ermittelten Temperaturen wurden mit einer andere Methode verglichen. Aus der Abschätzung ergab sich, dass die Plasmatemperatur bei gepulsten GD um bis zu 100 K gesenkt werden und durch die Pulsparameter genauer eingestellt werden kann. Der Einfluss des Sputterns auf Cu(In,Ga)Se2 (CIGSe) Dünnschichten von Solarzellen wurde erstmals beschrieben. REM-Untersuchungen an GD-gesputterten CIGSe Schichten haben gezeigt, dass die Sputtereffekte durch die Variation der Pulsparameter reduziert werden können. Es konnte gezeigt werden, dass HF- und DC-Entladungen dieselben Effekte aufweisen und sich nur geringfügig voneinander unterscheiden. Daraus kann geschlussfolgert werden, dass DC- und HF-Entladungen in Bezug auf elektrische Eigenschaften, Kraterformen, Lichtemission und Temperatur sehr ähnlich sind. Die Quantifizierung der mit gepulsten GD gemessenen Tiefenprofile ergab ferner, dass die Anwendung der Quantifizierungsmethoden für den kontinuierlichen Modus unter den gegebenen Bedingungen zulässig ist. Die Tiefenprofile von Solarzellen-Schichten sowie SAW-Metallisierungen wurden anhand gepulster GD gemessen und quantifiziert. Die empfohlenen Quantifizierungsmethoden können mit kommerziellen GD OES-Geräten durchgeführt werden. Die Untersuchungen an gepulsten GD sind insbesondere relevant für GD OES-Anwendungen im Bereich der Werkstoffwissenschaft. Während der Zusammenarbeit mit dem Helmholtz-Zentrum Berlin für Materialien und Energie und der Arbeitsgruppe von Dr. Thomas Gemming (IFW Dresden) konnten optimierte, gepulste GD OES Messungen erfolgreich zur Untersuchung von Dünnschicht-Solarzellen bzw. hochleistungsbeständigen SAW-Metallisierungen angewendet werden. Für die Solarzellen haben GD OES und SIMS Messungen geholfen, die Rolle der Al2O3-Barriere in CIGSe/Mo/Al2O3 Schichtstapeln auf flexiblem Stahlsubstrat besser zu verstehen (Al2O3 soll die Diffusion der Fe-Atome in CIGSe verhindern). Die gemeinsame Untersuchung getemperter CIGSe-Schichten mit gepulster GD OES und in-situ Synchrotron-XRD ergab neue Erkenntnisse zum Schichtwachstum. Der Diffusionskoeffizient von Zn in CuInS2 wurde erstmals aus GD OES-Tiefenprofilen bestimmt. Im Fall der SAW-Metallisierungen konnte die GD OES zur Bestimmung des geeignetsten Herstellungsverfahrens einen wichtigen Beitrag leisten. Die gepulste GD OES hat neben anderen Untersuchungsmethoden wie TEM-EDX, XPS und Lebensdauermessungen die Verbesserung der Leistungsbeständigkeit von Cu-Metallisierungen durch geringen Al-Zusatz aufklären können
34
Asil, Demet. "A Glow In The Dark: Synthesis And Electropolymerization Of Chemiluminescent Thiophene Derivatives." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609863/index.pdf.
Full textAbstract:
ABSTRACT
A GLOW IN THE DARK:
SYNTHESIS AND ELECTROPOLYMERIZATION OF CHEMILUMINESCENT THIOPHENE DERIVATIVES
Asil, Demet
M.Sc., Department of Chemistry
Supervisor : Prof. Dr. Ahmet M. Önal Co-Supervisor: Assist. Prof. Dr. Atilla Cihaner September 2008, 63 Pages Two novel chemiluminescent monomers, 2,3-dihydrothieno(3,4-d)pyridazine-1,4-dione (T-Lum) and 5,7-di-thiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (TTT-Lum), were synthesized. The reaction between T-Lum and TTT-Lum in alkaline solution with H2O2 gave chemiluminescence which can be catalyzed using Fe(III) ion. Owing to its sensitivitiy towards Fe(III) ion
T-Lum and TTT-Lum can be promising materials to detect bloodstains in the application of forensic science instead of luminol which gave response to a large family of metallic cations beside Fe(III). Also, TTT-Lum, which is based on a terthienyl system, was electropolymerized and its corresponding polymer (PTTT-Lum) was obtained via repetitive cycling or constant potential electrolysis in both 0.1 M LiClO4 dissolved in acetonitrile containing 5% of BF3-Et2O by volume and neat BF3- Et2O solution. In addition, PTTT-Lum, soluble in alkaline water, was synthesized successfully without breaking the pyridazinedione unit (chemiluminescent unit), as proved by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Electrochemical Luminescence (ECL) measurements. Thus, PTTT-Lum, bearing chemiluminescent unit, can be a good candidate to be used as a sensor in near future. Furthermore, the PTTT-Lum film has a very stable and well-defined reversible redox couple as well as electrochromic behavior during p-doping process. The polymer film has also a band gap of 1.74 eV with an absorption band in its neutral state at 536 nm. Finally, PTTT-Lum film was found to be electrochemiluminescence active, maintaining its activitiy over 1000 cycles.
35
Lin, Xin. "Yttrium disilicate as environmental barrier coating for silicon nitride-based glow plug." University of British Columbia, 2017. http://hdl.handle.net/2429/64165.
Full textAbstract:
Silicon-based ceramics undergo severe degradation at temperatures above ~1000 ℃ in the presence of water vapor, which is inevitable in combustion environments. Therefore, Environmental Barrier Coatings (EBCs) are necessary for the protection of Si₃N₄-based ceramic components in the harsh combustion environments. Rare earth silicates, which have relatively low thermal expansion coefficients, good chemical stability at high temperatures and low recession rates in the presence of water vapor, are promising candidate materials for such EBC application. This study was related to the application of Si₃N₄ as part of Hot Surface Ignition Systems (“Glow-Plugs”, GP) in High-Pressure Natural Gas Direct Injection engines, currently under development by Vancouver company Westport Fuel Systems Inc. For certain kinds of commercially available Si₃N₄-based GPs, the use of Y₂O₃ as sintering additive results in the in-service formation of yttrium silicates on their ceramic pins. Therefore, taking the chemical compatibility into consideration, yttrium disilicate coating was chosen to provide corrosion protection for such GPs. A sol-gel dip-coating route, which is simple, cost effective and industrially applicable, has been developed to apply multi-layer Y₂Si₂O₇ EBCs on the GPs. Selective processing parameters, including the sol aging conditions and the withdrawal speed of the GP substrate during dip coating procedure, were investigated in detail. The thickness and microstructures of the coatings were controlled through the adjustment of these parameters during sol preparation and dip coating processes. To simultaneously achieve sufficient thickness and avoid the formation of cracks, thin layers of Y₂Si₂O₇ coating, each with the thickness of ~1 µm, were successively applied and processed. The 6-layer crack-free coating was able to achieve an average thickness of ~5.5 µm. The microstructures of the coatings were evaluated and their performance was tested at ~1200 ℃ in high concentration water vapor atmosphere and on a natural gas burner rig. Improved corrosion resistance of such EBC-protected glow plugs was observed in these tests.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
36
Evans, D. R. "Multiple glow discharges for the excitation of a high power CO2 laser." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/31977.
Full textAbstract:
Multiple glow discharges have been studied and both electrode and aerodynamic techniques investigated to enable operation of a large volume high power glow discharge to excite a high power C02 laser. A wide range of electrode configurations was investigated and the advantages of using multiple anodes with large surface area multiple cathodes determined.
37
Karimi, Sharif Hamed. "Degradation of silicon nitride glow plugs in electric field-experiments and modeling." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/36256.
Full textAbstract:
Silicon nitride (Si₃N₄) based ceramic Glow Plugs (GP) are considered by the automotive industry as a reliable, long-term source of ignition for natural gas and hydrogen internal combustion engines. The commercial GPs investigated in this work comprised of an all-ceramic heater with two U-shaped tungsten carbide heating elements encased in an Yb₂O₃-doped silicon-nitride (Si₃N₄) insulating phase. Upon applying electric potentials of 10-14V, the temperature on the surface of ceramic heater rapidly raises to as high as 1500ºC. This work looks into various modes of deterioration of GPs, particularly resulting from interaction of high operating temperature and the electric field within the GP heaters. An extensive scanning electron microscopy and energy dispersive x-ray spectroscopy investigation was performed to determine the degradation mechanisms of GPs in natural gas-burning rig, electric rig and engine. GP testing has shown that under the influence of constant electric load (DC) the sintering aid (Yb₂O₃) cations continuously migrate away from the high potential side of the heating elements following the electric field pattern. A 2D mathematical model was developed to simulate the redistribution of the sintering additive (Yb₂O₃) cations as a function of time, temperature, and electric field. The damage pattern of the tested GPs suggests synergistic impact of temperature, voltage, and environment on GPs lifetime. For the GPs tested in the burner rig and in engine the internal joule heating, externally applied combustion heat, together with the corrosive nature of the combustion gases, synergistically contribute to the degradation of Si₃N₄-based heaters. The comparison of cross sections for aged GPs revealed an increase in Yb ions migration with increasing temperature, electric field, and test duration. This study confirms that the removal of just one of the failure stimuli may significantly improve the GP performance. For example, applying AC voltage provided a significant improvement of GP durability in electric rig, even without addressing any other damage phenomena.
38
Rutherford, Alasdair C. "Where is the warm glow? : the labour market in the voluntary sector." Thesis, University of Stirling, 2011. http://hdl.handle.net/1893/3066.
Full textAbstract:
Why do people work in the voluntary sector? Is the sector distinct, with characteristics that differentiate it from the private and public sectors? Is it important to consider the existence of the so-called ‘third sector’ when analysing behaviour in the labour market? Is altruism really an important motivation for workers in this sector? This dissertation is concerned specifically with the labour market in the voluntary sector: that is, workers who are the paid employees of independent nonprofit organisations. Using a large, national dataset, we explore empirically the predictions of the economic theory of voluntary organisations. In particular, is there evidence for a ‘warm glow’, the extra utility that workers receive for working towards a goal that they share with their employer? Does this glow exist, and is it brighter in the voluntary sector? We examine in turn sector differences in wages, working hours, and find evidence that employment in the voluntary sector is significantly different in some characteristics from both the private and public sectors. The main economic theories of voluntary sector wage-setting rely on some formulation of ‘warm glow’ utility or intrinsic motivation derived from working for an organisation with a mission shared by motivated employees. This leads to a prediction of lower wages in the voluntary sector. The empirical findings in the existing literature have focussed on US data, and the results have been mixed. Using pooled cross-sectional and panel datasets based on UK employment data between 1997 and 2007, we show that there is some evidence of warm-glow wage discounts in the sector for male workers, but that these wage differences have been eroded as the sector has grown. Although there is not a significant sector wage difference found for women, there is evidence that they have also experienced faster wage growth in the voluntary sector than the private. There are significant sector differences in working hours within the Health & Social Work industries, particularly in overtime working. Workers in the voluntary sector work more hours of unpaid overtime, whilst those in the private sector work more hours of paid overtime. Controlling for overtime hours has a significant effect on sector wage differentials. In particular, accounting for unpaid overtime results in evidence of a warm-glow wage discount for female workers. We analyse this data at a time when the sector has been growing dramatically, driven by government policy to reform public services. Our findings suggest that this policy has had unintended consequences for the voluntary sector labour market.
39
Zhang, Qinglin. "Pore structure control and glow discharge treatment of alumina catalyst support material." Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1409.
Full text
40
Paterson, Alexander Miller. "Continuous wave laser induced fluorescence investigation of a neon normal glow discharge." Thesis, University of Strathclyde, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397765.
Full text
41
Sheu, Min-Shyan. "Glow discharge immobilization of polyethylene-oxide-containing surfactants for non-fouling surfaces /." Thesis, Connect to this title online; UW restricted, 1992. http://hdl.handle.net/1773/8021.
Full text
42
Absalan, Ghodratollah Carleton University Dissertation Chemistry. "Atomic absorption spectrometry with atomization by cathodic sputtering in a glow discharge." Ottawa, 1996.
Find full text
43
Brewer, Tim M. "The glow discharge - a multifaceted optical emission source from solids analysis to metalloproteins /." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1181251765/.
Full text
44
Webb, Michael R. "New designs and detection strategies for glow discharge as an alternative spectrochemical source." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3277964.
Full textAbstract:
Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007.Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5920. Adviser: Gary M. Hieftje. Title from dissertation home page (viewed May 8, 2008).
45
Williams, D. R. "Fast flowing glow discharge quadrupole mass spectrometry : source design, development, characterisation and theory." Thesis, Swansea University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636622.
Full textAbstract:
This thesis describes the development and characterisation of two second-generation Fast Flowing Glow Discharge (FFGD) ion sources for analytical applications. These sources are interfaced with a quadrupole based mass spectrometer. Optimisation of the source parameters enables selective enhancement of the analyte ions whilst reducing the levels of the interfering ions (discharge gas and contaminant ions), producing a cleaner mass spectrum and higher analyte ion currents. Investigations have shown behaviour that is inconsistent with ionisation processes based solely on conventional models. This indicates that other ion-formation processes also occur within the argon glow discharge plasma, especially under short gas residence time conditions. Preliminary analytical work suggests that these sources achieve good internal precision (< 10%), detection limits in the 1-100 ppb range and Relative Sensitivity Factors in the range 0.4-5.0. These results indicate the potential of both sources for elemental analysis. The addition of 1-2% secondary hydrogen of the afterglow of the flowing plasma selectively enhances the metal ion signals. The interfering ions are also selectively reduced, to the point of negligible presence. These results are consistent with previous work from this laboratory, which suggests that the ions sampled from short residence time plasmas are as a result of neutral ionisation processes involving highly excited state species close to the ion exist aperture. Ionisation is caused by field/chemi-ionisation reactions at the ion exit aperture. The work in this thesis demonstrates that the Fast Flowing Glow Discharge source can be used as a sensitive elemental technique. In a separate piece of work, Collision Induced Dissociation Mass Spectrometry was used to investigate the pressure and temperature effects on the thermal (low energy) ionisation processes in cyclohexane. Although the project was unsuccessful in distinguishing the presence of the three C6H11+ isomers, the work is instructive with regards to the limitations of the technique used.
46
Sarwar, Mirza Saquib us. "Dimensional modification of vertically aligned carbon nanotubes using miniaturized arc and glow discharges." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46291.
Full text
47
Hughes, Jerry W. (Jerry Wayne) 1975. "A device for tritium enrichment of glow discharge polymer inertial confinement fusion targets." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85319.
Full text
48
Li, Qile. "Combustion aided by a glow plug in diesel engines under cold idling conditions." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/35875/.
Full textAbstract:
Glow plugs are widely used to promote the desired cold start and post-cold start combustion characteristics of light duty diesel engines. The importance of the glow plug becomes more apparent when the compression ratio is low. An experimental investigation of combustion initiation and development aided by the glow plug has been carried out on a single cylinder HPCR DI diesel engine with a low compression ratio of 15.5:1. High speed imaging of combustion initiated by the glow plug in a combustion bomb has been used to add understanding of initiation process. Complementary CFD studies have been carried out using ANSYS Fluent 14.0 to explore the interactions between the glow plug and the spray behavior. Observation of successful combustion initiation show that two conditions must be met, compression heating and heat transfer from the glow plug must raise temperature of gas nearby to at least 413ºC and the vapour/air equivalence ratio no lower than 0.15-0.35. The initiation site was at spray edge close to the glow plug, the flame grew locally before expanding downstream in direction of spray penetration after the end of the main injection. Experimental studies carried out on the engine indicated that the engine IMEP, heat release and combustion stability were continuously improved by using the glow plug at ambient temperatures higher than the temperature requiring the glow plug for initiation of combustion. A rapid development of premixed combustion was achieved associated with improved engine work output, heat release rate and cycle-by-cycle stability. The premixed combustion was enhanced by strengthening spray vaporization through the glow plug. In this study, the combustion behavior was enhanced by the glow plug up to ambient temperature of 20ºC. Initiation delay was shortened by a rapid development of combustion aided by the glow plug. An initiation delay model was developed to account for both physical part (transport delay) and chemical part (chemical delay). The transport delay (ms) is equivalent to the time for spray to transport to the vicinity of the glow plug, dictated by parameters including S, distance between the glow plug tip and the injector tip (mm).
49
Headrick, Kurt Lee Carleton University Dissertation Chemistry. "Atomic absorption spectrometry with sample atomization by cathodic sputtering in a glow discharge." Ottawa, 1991.
Find full text
50
Dickinson, Paul Michael. "The study of Rydberg gas chemistry by fast flow glow discharge mass spectrometry." Thesis, Swansea University, 2008. https://cronfa.swan.ac.uk/Record/cronfa42439.
Full textAbstract:
This study concerns the analysis of processes occurring within, and fundamental characteristics of the flowing afterglow of a fast flowing direct current glow discharge plasma by both mass spectrometric and electrical diagnostic techniques. The evidence presented within this thesis indicates that the glow discharge plasma studied contains a high density of very highly excited state, Rydberg species. Classically, glow discharge plasma is considered to be a partially ionised gas, the chemistry of which is dominated by processes involving charged particles (ions and electrons). However, under the conditions of the fast flow glow discharge source it is thought that the formation and stabilisation of Rydberg atoms is highly favourable, and thus the plasma chemistry can be described by a Rydberg gas model. Theoretical thermodynamic and kinetic data based on calculations (unpublished at the time of submission) performed by Dr R. S. Mason which corroborate this model are also presented. Studies of the influence of the magnitude and polarity of applied the ion exit bias on the electrical properties of the flowing afterglow plasma and active discharge region were undertaken, often in situ with mass spectrometric measurements. Comparison of the electrical and mass spectrometric measurements has provided valuable information about the properties of the Rydberg gas plasma and the ionisation processes within the afterglow plasma. The results of the electrical studies (current and double probe measurements) could not be explained for an ion electron medium. The reactions of secondary gases (H[2], CO, CO[2], N[2], CF[4] and CH[4]) and organic vapours to the flowing afterglow plasma have been studied for a range of conditions. The results of which cannot all be explained by ion-molecule processes, and seemingly conform to the Rydberg gas model.