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1
Mynors, Diane Julie. "Modelling of volume ion sources." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333192.
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Perez, Martinez Carla S. (Carla Sofia). "Engineering ionic liquid ion sources for ion beam applications." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105605.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 177-186).
Ionic liquid ion sources (ILIS) are devices capable of producing positive and negative molecular ion beams through field evaporation from room-temperature molten salts. If sufficiently high hydraulic impedance from the liquid-supporting emitter is provided such that the ratio of flow rate Q to liquid's electrical conductivity K is sufficiently small, a pure ionic regime (PIR) can be achieved, in contrast with traditional electrosprays that produce charged droplets, or mixtures of droplets and ions. The PIR provides high current density from a point source, making ionic liquid ion beams suitable for use in focused ion beam (FIB) applications. The use of ionic liquids in focused ion beams could allow the production of sub-100 nm beams of up to kiloDalton organic ions as well as reactive species, with the possibility of engineering ionic liquid properties for a specific application. In addition, using micro-fabricated and nano-structured emitter arrays operating in the PIR can give access to efficient and compact positive or negative ion sources, for applications from spacecraft thrusters to deep reactive ion etchers (DRIE). There is a need for novel tip geometries and materials that favor the stable formation of a single emission site on the liquid supporting structure, while providing a continuous liquid supply compatible with the PIR. In this thesis, porous carbon based on resorcinol-formaldehyde xerogels is introduced as an emitter substrate. The target pore sizes and emitter geometries to attain the PIR are obtained through analytical estimates. The carbon xerogel can be shaped to the required micron-sized geometry through mechanical polishing. Time-of-flight mass (TOF) spectrometry is used to verify that charged particle beams produced from the mechanically polished carbon xerogel source, infused with the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF₄), contain solvated ions exclusively. In the case of the liquid 1-ethyl-3-methylimidazolium bis(trifluorometrylsulfonyl)imide (EMI-Im), mixed ion-drop operation is obtained. Laser micro-machining has been validated as a manufacturing technique to shape carbon xerogel into emitters. This technique should allow the production of emitter arrays for DRIE or propulsion applications, and allow the reproducible fabrication of emitters for FIB. Stable emission has been obtained from a laser micromachined tip infused with the ionic liquid EMI-BF₄ . The results of TOF and retarding potential analysis (RPA) experiments indicate that the emission consists mostly of monomers and dimers, and that a small fraction (< 5%) of the beam might be composed of cluster ions with greater degrees of solvation. To conclude, the thesis reports on the etching properties of the beams obtained from ILIS, both in the case of traditional externally wetted tungsten sources and with the novel carbon xerogel emitter technology. The W ILIS etches silicon with sputtering rates between 6 and 35 atoms of silicon removed per incident ion at 15 keV irradiation energies, whereas the carbon xerogel ILIS has been used to etch gold, silicon and gallium nitride with sputtering rates in the order of 10 for irradiation energies between 2 and 7 keV.
by Carla S. Perez Martinez.
Ph. D.
3
Hornsey, Richard Ian. "Factors affecting ion energy distributions in liquid metal ion sources." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236154.
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Papadopoulos, S. "Atomic and cluster ion emission from liquid metal ion sources." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375310.
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Miller, Catherine Elizabeth. "Characterization of ion Cluster fragmentation in ionic liquid ion sources." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122372.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 273-281).
Ion electrospray propulsion is a cutting-edge micropropulsion technology that could revolutionize the capabilities of microsatellites. Ion electrospray thrusters could also be used on large spacecraft for precision attitude control applications such as gravity wave detection and exoplanet imaging. Novel room temperature molten salts, called ionic liquids, are used as propellant, which are composed purely of positive and negative molecular ions. When exposed to strong electric fields, ions and metastable clusters of ions are evaporated from the bulk liquid surface. The free ions and ion clusters can be accelerated to high velocities, producing thrust at high specific impulse. The performance of ion electrospray thrusters is affected by the composition of the ion beam and the amount of ion clusters that break apart during the acceleration phase. To improve thruster performance, a better understanding of the fundamental physics of ion evaporation and cluster break-up is needed.
The break-up of ion clusters, also called fragmentation, is not a well understood phenomenon. It has been observed in past experiments, but the rates of break-up have not been measured. The focus of this work is to experimentally investigate fragmentation more deeply than ever before. To accomplish this, a specialized instrumentation suite has been designed, built, and tested to measure fragmentation characteristics in unprecedented detail. A full-beam, spherical geometry retarding potential analyzer is used to measure the rates of fragmentation of ion clusters both outside the thruster and within the acceleration region for the first time. A narrow-beam, high time-resolution time of flight mass spectrometer is used to measure the beam composition. Single emitters based on resorcinol formaldehyde carbon xerogels were used as ion sources. Four ionic liquids spanning a wide range of liquid properties were characterized: EMI-FAP, EMI-Im, EMI-BF4, and BMI-I.
Analytical models were also developed to enhance the interpretation of the experimental results. The experimental measurements show that the amount of fragmentation increases with distance from the thruster and follows a constant rate equation. The mean lifetimes of ion clusters outside of the thruster range from 1-6 [mu]s, indicating that these clusters are quite unstable. It is observed that the fragmentation throughout most of the acceleration region is linear with respect to electric potential, which can be understood using analytical models. Rapid fragmentation likely occurs immediately after evaporation due to the strong electric fields near the emission site, which has significant implications for thruster performance. It is also observed that clusters of complex molecular ions which consist of many atoms tend to be the most stable. The initial temperature of ion clusters, which range from 520 K - 790 K, were estimated using analytical methods.
The effect of liquid temperature on the rates of fragmentation was also investigated. In conclusion, the work in this thesis provides a greatly enhanced understanding of ion cluster fragmentation, particularly how it is affected by ionic liquid properties, liquid temperature, and electric fields.
This research was supported by a NASA Space Technology Research Fellowship
by Catherine Elizabeth Miller.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Perez, Martinez Carla S. (Carla Sofia). "Characterization of ionic liquid ion sources for focused ion beam applications." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82506.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013.This thesis was scanned as part of an electronic thesis pilot project.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 79-82).
In the Focused Ion Beam (FIB) technique, a beam of ions is reduced to nanometer dimensions using dedicated optics and directed to a substrate for patterning. This technique is widely used in micro- and nanofabrication for etching, material deposition, microscopy, and chemical surface analysis. Traditionally, ions from metals or noble gases have been used for FIB, but it may be possible to diversify FIB applications by using ionic liquids. In this work, we characterize properties of an ionic liquid ion source (ILIS) relevant for FIB and recommend strategies for FIB implementation. To install ILIS in FIB, it is necessary to demonstrate single beam emission, free of neutral particles. Beams from ILIS contain a fraction of neutral particles, which could be detrimental for FIB as they are not manipulated by ion optics and could lead to undesired sample modification. We estimate the neutral particle fraction in the beam via retarding potential analysis, and use a beam visualization tool to determine that most of the neutral population is located at the center of the beam; the neutral population might then be eliminated using filtering. The same instrument is used to determine the transition of the source from single to multiple beam emission as the extraction voltage is increased. These studies should guide in the design of the optical columns for an ILIS-based FIB.
by Carla S. Perez Martinez.
S.M.
7
Miller, Catherine Elizabeth. "On the stability of complex ions in ionic liquid Ion sources." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98808.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 139-141).
Ionic liquids are molten salts at room temperature that consist of positive and negative ions. These liquids can be used in electrosprays to produce ion beams. Ionic liquid ion source (ILIS) beams typically consist of single ions and solvated ions. It has been observed that solvated ions are not always stable and can break up into lighter ions midflight. Past experiments show that the stability of solvated ions depends on the molecular composition of the ionic liquid. Based on these results, it has been hypothesized that the stability of solvated ions increases with increasing molecular complexity of the ions. The focus of this work is to test this hypothesis by characterizing ionic liquids of different molecular complexities under controlled conditions. A time of flight mass spectrometer and a retarding potential analyzer were developed specifically for this purpose. The ion beam composition and energy distribution were measured at various temperatures and source voltages for each ionic liquid. With some exceptions, the observed trend was in agreement with the results of past experiments and with the hypothesis. The exceptions to the expected trend may have resulted from the limitations of the detectors. The data from this work can be used to test the hypothesis with moderate confidence. Future study requires improvements to the detectors, namely the retarding potential analyzer, so that the hypothesis can be evaluated more conclusively.
by Catherine Elizabeth Miller.
S.M.
8
Dowsett, David Mark Francis. "High Brightness Ion Sources for Surface Analysis." Thesis, University of Warwick, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491929.
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The aim of this work was to produce an ion source with a high brightness and low energy spread. Two approaches were taken, an existing high brightness ion source (the liquid metal ion source) was monochromated to reduce its energy spread; this work was carried out at the University of York. The second approach was to develop a novel high brightness ion source with an intrinsically low energy spread. This approach was carried out at the University of Warwick. Several potential monochromators were simulated and the concentric hemispherical analyser was found to be the most suitable. Liquid metal ion sources were fabricated for monochromation by the author. However, these sources did not prove to be sufficiently stable for energy spread measurements and electron sources were used to try to demonstrate the principal. Ultimately this approach did not prove successful and the alternative ofdeveloping a novel source was pursued. This second approach utilises a novel emission process discovered at Warwick: surface enhanced field emission. Alkali metal vapours incident on a hot, chemically etched molybdenum wire are ionised at fields much lower than those normally required for field emission. Emission currents of several microamps have been obtained from the source and the sample current found to extremely stable with r.m.s noise of just 0.65%. The axial angular intensity of the source is 23 ~A sfl at 1 ~A emission. SIMS depth profiling has been carried out and the dynamic range at 1 keY was 3 orders of magnitude. Spot sizes of 20 ~m have been measured at 1 keY. The dynamic range and spot size do not represent the ultimate performance of the source, both are expected to improve in an ion column designed for a high brightness source.
9
Gotoh, Yasuhito. "Development of Novel Metal Ion Beam Systems with Liquid-Metal Ion Sources." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/77906.
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Petrov, A., A. Alexandrov, E. Kralkina, P. Nekliudova, K. Vavilin, and V. Pavlov. "Advanced Ion and Plasma Sources for Materials Surface Engineering." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35409.
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The paper presents the results of the authors many year work in the field of ion&plasma sources development.
The families of DC and RF ion and plasma sources are described. The results of ion&plasma
sources utilization in materials surface modification technologies are discussed.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35409
11
Rao, Radhakrishna A. "Nanoscale microfabrication prospects using proximity focused liquid metal ion sources /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,183.
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Cowen, M. C. "Space charge effects in ion sources for quadrupole mass spectrometers." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337960.
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Calburean, Alexandru D. "Performance impact of ion sources in Inertial Electrostatic Confinement devices." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/129867.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, February, 2020Cataloged from student-submitted PDF of thesis. "February 2020."
Includes bibliographical references (pages 38-39).
In order to improve the performance of Inertial Electrostatic Confinement (IEC) based fusion devices, so as to improve their effectiveness as low cost, portable neutron sources, a novel use of ion sources is proposed as a means of increasing fusion reaction rate at similar power levels. This paper aims to determine the success and practicality of the proposed use type for ion sources and characterize the IEC device in question, in terms of performance, and neutron emission. The application outlined aims to improve upon the performance of IEC devices with an anode layer ion source. The above-mentioned approach was evaluated by first conditioning the IEC fusion device in question. Then a neutron flux baseline was recorded as a metric for performance, and to evaluate the assumption of neutron emission isotropy in the device. Then an ion source was installed in the chamber, and the system was once again conditioned in the same manner. A similar baseline reading and analysis was done to ensure a correct comparison could be made between performance with the ion source turned on and off. Next the system was run with the ion source at full power to allow for further characterization of the performance and stability of the device. Finally, a last run was carried out with the ion source properly tuned, and results were compared to both baseline runs. It has been shown that there is a potential performance gain from operation with an ion source, both in terms of system stability and improved neutron emission. Across all run campaigns, the assumption of isotropic emission was shown to be a poor representation of the actual emission. With a higher degree of certainty, it has been shown that operation with an ion source serves to reliably exaggerate the anisotropy found in baseline campaigns.
by Alexandru D. Calburean.
S.B.
S.B. Massachusetts Institute of Technology, Department of Nuclear Science and Engineering
14
Gallagher, Richard Thomas. "Kinetics and equilibria of ion-molecule association reactions : studied using temperature variable high pressure ion sources." Thesis, University of Warwick, 1987. http://wrap.warwick.ac.uk/4160/.
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Interest in termolecular association reactions of the type shown below, stems from their importance in the chemistry of planetary atmospheres, gas-cooled nuclear reactors and gas-phase cluster ions. This study is concerned with evaluating the rate constants of such X+ + X + M ------> X2+ + M k3 (1) reactions as both a function of temperature and of the third body M. The values of the third order rate constant k3 are expressed conventionally in terms of k3 = CT-m where T is the temperature and C and m are constants characteristic of the reaction which depend also on the nature of M. Literature now shows a general measure of agreement on values of C and m in several studies for which X=M, however, inconsistent values have been reported on the M=He system. This thesis describes an investigation of the two systems X=N2, CO and M= the reactant or a rare gas. Experiments were conducted in a conventional high pressure ion source and a pulsed drift ion source fitted to an updated Kratos MS9 mass spectrometer. Results obtained for the one component studies show good agreement with other literature values for the temperature dependence, m. In general, for both N2 and CO systems, He was found to have the same efficiency as the parent molecule as a third body at 300K, but the temperature dependence of k3 is markedly lower. Ar was found to behave very similarly to the parent molecule in both systems. For the CO system, although good agreement is found for the temperature dependence result with literature, there is still an uncertainty of about a factor of 2 in the room temperature values of k3.
15
Hoepfner, Patrick J. "A Monte Carlo calculation of virtual source size and energy spread for a liquid metal ion source /." Full text open access at:, 1985. http://content.ohsu.edu/u?/etd,77.
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Johnson, Samantha. "Optimizing the ion source for polarized protons." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&.
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Beams of polarized protons play an important part in the study of the spin dependence of the nuclear force by measuring the analyzing power in nuclear reactions. The source at iThemba LABS produces a beam of polarized protons that is pre-accelerated by an injector cyclotron (SPC2) to a energy of 8 MeV before acceleration by the main separated-sector cyclotron to 200 MeV for physics research. The polarized ion source is one of the two external ion sources of SPC2. Inside the ion source hydrogen molecules are dissociated into atoms in the dissociator and cooled to a temperature of approximately 30 K in the nozzle. The atoms are polarized by a pair of sextupole magnets and the nucleus is polarized by RF transitions between hyperfine levels in hydrogen atoms. The atoms are then ionized by electrons in the ionizer. The source has various sensitive devices, which influence beam intensity and polarization. Nitrogen gas is used to prevent recombination of atoms after dissociation. The amount of nitrogen and the temperature at which it is used plays a very important role in optimizing the beam current. The number of electrons released in the ionizer is influenced by the size and shape of the filament. Optimization of the source will ensure that beams of better quality (a better current and stability) are produced.
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Wißdorf, Walter [Verfasser]. "Simulation of Ion Dynamics in Atmospheric Pressure Ionization Sources / Walter Wißdorf." Wuppertal : Universitätsbibliothek Wuppertal, 2014. http://d-nb.info/1063047110/34.
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Zorzos, Anthony Nicholas. "The use of ionic liquid ion sources (ILIS) in FIB applications." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/51647.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Includes bibliographical references (leaves 82-86).
A new monoenergetic, high-brightness ion source can be constructed using an arrangement similar to liquid metal ion sources (LMIS) by substituting the liquid metal with an ionic liquid, or room temperature molten salt. Ion beams produced by these ionic liquid ion sources (ILIS) have energy deficits and distributions that closely resemble their metallic counterparts, with the exception that, if needed, they can be stably operated at current levels as low as a few nA. ILIS sources are here presented as having two further key advantages: (1) the ability to obtain both positive and negative ion beams, and (2) the ability to produce very diverse molecular ions in terms of their masses, compositions and properties, due to the fact that the number of available ionic liquids is large. In this thesis an overview of ILIS sources is presented, as well as preliminary results of their performance in a FIB column.
by Anthony Nicholas Zorzos.
S.M.
19
Wilde, Nicholas David. "Optimization of surface dielectric barrier discharge ion sources for electroaerodynamic propulsion." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127106.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 33-34).
Surface dielectric barrier discharges (SDBDs) are a type of asymmetric dielectric barrier discharge (DBD) that can be used to generate ions and produce aerodynamic forces in air. They have been studied for aerodynamic flow control and proposed for small aircraft propulsion as both direct sources of thrust and as ion sources for "decoupled" electroaerodynamic (EAD) propulsion, in which decoupling ionization from ion-acceleration provides performance and control advantages. SDBDs can also be integrated into aircraft surfaces without introducing additional drag. A challenge for these aerospace applications is minimizing the power draw (or maximizing the efficiency) of these actuators. Optimizing SDBD actuators requires a robust model for SDBD electrical power draw as a function of geometric, material, and electrical properties.
Existing approaches use empirical power law fits to estimate the power of a specific DBD configuration at certain electrical operating points; they are challenging to use in engineering design and optimization as they require experimental measurements for each individual configuration. This thesis proposes the first physics-based model for surface DBD power consumption. The proposed model is based on established models for parallel-plate or "volume" DBDs, and it incorporates the effect of changing plasma length that is specific to SDBDs. This thesis examines SDBDs of three materials, eleven thicknesses, and 394 unique electrical operating points and finds a correlation with R² = 0.99 (n = 394) between experimentally-measured power and model-predicted power. SDBD power measurements extracted from four other experiments from the literature are analyzed with a correlation of R² = 0.97 (n = 101), demonstrating that the model is generalizable to other SDBD constructions.
Ionization rate is also measured to facilitate optimization for use in decoupled EAD thrusters. This work enables the quantitative design and optimization of SDBDs for EAD propulsion and other applications in aerospace and beyond.
by Nicholas David Wilde.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Puretz, Joseph. "A theoretical and experimental study of liquid metal ion sources and their application to focused ion beam technology /." Full text open access at:, 1988. http://content.ohsu.edu/u?/etd,182.
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Bozack, Michael J. "Surface phenomena in liquid metal alloys with application to development of a liquid metal ion source of B and As /." Full text open access at:, 1985. http://content.ohsu.edu/u?/etd,76.
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Sakildien, Muneer. "Plasma characterisation of an electron cyclotron resonance ion source by means of x-ray spectroscopy." Thesis, University of the Western Cape, 2012. http://hdl.handle.net/11394/5212.
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>Magister Scientiae - MScThe ultimate aim of any multiply-charged ion source, like the Electron Cyclotron Resonance Ion Source, ECRIS, is the production of multiply-charged ions, in sufficiently large quantities. These multiplycharged ions, in the case of the ECRIS, are created by a step-by-step ionisation process, whereby neutral atoms are ionised by energetic electrons. The goal of this thesis was to gain an understanding of the relative importance of various ECRIS parameters on the production of these energetic electrons. This was done by measuring the bremsstrahlung continuum emitted by the mirror confined plasma of an ECR ion source. The focus of our study was to investigate the influence of neutral pressure, incident microwave power and magnetic field configuration on spectral temperature and electron density of the warm electron population of the ECRIS plasma. The thesis begins by familiarising the reader with various aspects of plasma physics as it relates to the measurements. The measurements were done with a high-purity germanium detector and processed with the DGF Pixie-4 module. Analyses of the measured spectra were done with subroutines written in Root. From the measured result, it was concluded that by increasing the incident microwave power from 50 W to 300 W, the spectral temperature increases by 14.01% for helium plasma and 7.88% for argon plasma. Evidence of saturation of spectral temperature and electron density with increasing microwave power was also noticed, as reported by other groups investigating plasma bremsstrahlung. The increase of spectral temperature with neutral pressure was found to be considerable, increasing by 20.23% as the neutral pressure in the plasma chamber of the ECRIS was decreased. This increase in spectral temperature was accompanied by a 40.33% decrease in electron density, which led us to conclude that the increase in spectral temperature was most likely due to an increase in the mean free path of the electrons. The influence of the magnetic field configuration on both spectral temperature and electron density was also investigated. During this investigation, one of the solenoid coil currents was increased, whilst keeping the other constant. This amounts to moving the plasma volume around axially in the plasma chamber of the ECRIS. This was found to significantly enhance the spectral temperature and this effect was attributed to more efficient heating of the electrons near the resonance zone. The electron density on the other hand was found to remain relatively constant, if one excludes the electron density as a result of one particularly setting of the solenoid coils. The decrease of electron density as a result of this particular setting of the solenoid coils enhanced the electron losses through the magnetic bottle. This is evidenced by the increase in photon counts as measured by our detector. The influence of neutral pressure, incident microwave power and magnetic field configuration on the extracted ion beam intensities was also investigated. This investigation led us to conclude that the mean charge state extracted increases with spectral temperature. This result was in agreement with those measured by other groups.
23
Verzeroli, Elodie. "Source NAPIS et Spectromètre PSI-TOF dans le projet ANDROMEDE." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS221/document.
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Le projet ANDROMEDE a pour but de créer un nouvel instrument d’imagerie ionique sub-micrométrique et d’analyse par spectrométrie de masse, en utilisant l’impact d’ions sur des nano-objets présents à la surface des échantillons solides et plus particulièrement sur les échantillons biologiques. L’étude de ces échantillons avec l’objectif d’analyse in vitro et in vivo nécessite une préparation complexe et requiert une expérimentation à la pression atmosphérique. Cet instrument unique ouvre une nouvelle voie dans l’analyse de surfaces, complémentaire aux méthodes utilisées de nos jours.Au sein du projet ANDROMEDE, deux éléments ont été développés dans le cadre de notre étude. La source NAPIS qui délivre les nanoparticules permettant d’augmenter le rendement d’éjection des ions secondaires, et le spectromètre de masse PSI-TOF pour l’analyse chimique des éléments émis depuis la surface de l’échantillon.Le faisceau primaire de nanoparticules de la source NAPIS est accéléré dans un accélérateur de type Pelletron 4MeV et amené sur une cible. La source de nanoparticules NAPIS a été développée et validée indépendamment au sein de la société ORSAY PHYSICS, avant son couplage sur l’accélérateur.Une nouvelle optique d’extraction appelée ExOTOF ainsi que le spectromètre de masse à extraction orthogonale PSI-TOF ont été développés pour permettre l’analyse des ions secondaires et augmenter la résolution en masse du système. Ces ensembles ont été spécialement dessinés pour ce projet. Ils permettront une extraction et une analyse efficace des ions secondaires émis depuis la surface de l’échantillon en utilisant des faisceaux continus et auront leur application pour les analyses à la pression atmosphérique. L’ensemble a été validé et les premiers tests de sortie du faisceau primaire ont été réalisés avec succèsThe goal of the ANDROMEDE project is to create a new instrument for sub-micrometric ion imaging and analysis by mass spectrometry, using ion impacts on nano-objects present in the solid sample surface and more particularly on biological samples. In-vitro and in-vivo analysis of these types of samples require mostly complex preparation and even atmospheric pressure experimentation. This unique instrument opens a new path for surface analysis characterization, which is complementary to the standard methods and technics used today.In the ANDROMEDE project, two elements have been developed in our study. The NAPIS source which delivers the nanoparticles allowing the increase of the secondary ion yield and the PSI-TOF mass spectrometer for the chemical analysis of the elements emitted from the sample surface.The NAPIS source delivers a primary beam of accelerated nanoparticles in a Pelletron 4MeV accelerator which is driven to a target. The NAPIS nanoparticles source has been developed and validated independently in the ORSAY PHYSICS Company firstly before its coupling on the accelerator. The new extraction optics called ExOTOF as well as the PSI-TOF orthogonal extraction mass spectrometer have been developed for the reliable secondary ions study and the increase of the mass resolution.These instruments have been specially designed for this project. This development will allow an efficient extraction and analysis of the secondary ions emitted from the sample surface using continuous primary beams and will have applications for atmospheric pressure studies. The assembly has been completely validated and the first tests of the output beam have been successfully carried out
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Khodja, Hicham. "Etude, conception et realisation d'une source d'ions micro-ebit." Paris 6, 1993. http://www.theses.fr/1993PA066133.
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Les sources d'ions multicharges de type ebis fonctionnant a l'heure actuelle font toutes appel aux techniques cryogeniques pour des raisons de pompage et de compression magnetique; les couts de fabrication et d'utilisation sont par consequent relativement eleves. Il existe neanmoins un domaine ou les sources de type ebis peuvent se passer des techniques cryogeniques, celui des faibles facteurs de compression et forts courants. Dans cette optique, une source baptisee micro-ebit, derivee d'un klystron amplificateur, a ete concue et realisee afin de verifier s'il est possible de produire des ions multicharges avec les parameres definis ci-dessus. Cette source ne dispose pas de systeme d'extraction; les ions sont detectes in situ par l'intermediaire des rayons x emis lors de leurs interactions avec le faisceau electronique. Apres un inventaire des sources ebis et ebit fonctionnant dans le monde, nous decrivons la physique et la technologie de ce type de source, dont le principe de fonctionnement repose sur l'ionisation pas-a-pas d'ions pieges par la charge d'espace du faisceau electronique. Dans une seconde partie, nous decrivons le dispositif micro-ebit, de sa conception aux premiers essais de transport de faisceau. Les performances prevues de la source par des simulations numeriques et des essais de vide sont precisees: densite de courant de l'ordre de 100 a/cm#2 pour un faisceau de 1 ampere-10 kev se propageant dans un vide de l'ordre de 1. 10##1#0 mbar, temps de confinement de 1 seconde pour produire de l'argon heliumoide. La derniere partie est consacree aux resultats experimentaux qui sont analyses apres description des diagnostics aux rayons x qui ont ete employes. La source micro-ebit a permis de produire divers ions, dont de l'argon 16+, avec le temps de confinement prevu
25
Panitzsch, Lauri [Verfasser]. "Spatial Distribution of Charged Particles Along the Ion-Optical Axis in Electron Cyclotron Resonance Ion Sources - Experimental Results / Lauri Panitzsch." Kiel : Universitätsbibliothek Kiel, 2013. http://d-nb.info/1031421483/34.
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Castro, Giuseppe. "Study of innovative plasma heating methods and applications to high current ion sources." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1433.
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The use of plasmas in various areas of scientific research has been growing
in recent years. The plasma is excited by microwaves typically in the range 2.45-28 GHz;
microwaves are coupled to a cylindrical chamber working as resonant cavity, where the plasma is produced, by a suitable system of waveguides, and are absorbed therein during the interaction with gases or vapors fluxedd at low pressure. Most of the parameters of the extracted beam, such as the intensity, the emittance and the shape in the real space depend in a decisive way on the characteristics of the plasma which from which the beam is extracted. The further development of ECR-type ion sources is however intrinsically limited by physical properties of the plasmas. The electromagnetic energy can not be transferred to the plasma electrons over a certain density threshold, named cutoff density, The studies we performed during the PhD course, carried out on a MDIS,
have shown that it is possible to excite waves in magnetized plasmas having an electrostatic nature (Electrostatic Bernstein Waves) which are not reflected at the density cutoff. An electrostatic wave is a rarefaction-compression wave whose electric field is parallel to the wave propagation direction. In particular, Electron Bernstein Waves (EBW) can be strongly absorbed by the plasma at cyclotron harmonics. Due to their electrostatic nature, EBW must be generated within the plasma from electromagnetic waves, through a conversion mechanism which takes from an electromagnetic wave to electrostatic oscillations (conversion mechanisms are typically called XB or OXB mechanisms). the research has been based on the detecting of peculiar signatures of the ES waves formation and following absorption: the overcoming density cut-off, the observation of non-linear heating, highlighted by the sudden appearance of X-ray emission above certain thresholds of RF power and finally, the broadening of electromagnetic spectrum, sign of interaction between the electromagnetic wave and the plasma waves. The three signatures have been simultaneously revealed for the first time in a compact device, the Plasma
Reactor, in two different magnetic configurations. In magnetic beach configuration, working at 3.76 GHz, a density value two times larger than cutoff density.
Double temperature electron population have been revealed correspondingly to the first harmonics. Flat-B configuration has been studied by using different frequencies, 2.45 and 3.75 GHz, and in both cases overdense plasmas have been generated. These data show that the new heating method enables to reach very high densities by using very low nominal power without a complication of the
technological apparatus. The data collected by means of X spectroscopy
help to understand the non-linearity extent triggered by the RF power and
able to convert the incident E.M wave in a plasma wave. Beyond the threshold microwave power, spectral temperature up to 4 keV has been obtained at 3.75GHz. This value need to be compared with the maximum energy obtainable by an electron from ECR heating, 200 eV. This further confirm that the heating mechanism is not the ECR. In this conditions plasma reactor has been demonstrated to be a very intense X-rays source.
The measurements on the VIS source have definitively demonstrated that X ray radiation is emitted only when a under-resonance region in the source exists. Along with the mentioned evidences, we also observed other
phenomena (all of them correlated to the occurred conversion) like a plasma
vortex formation: a double picked maxwellian distribution in resonance regions,
together with a variation in the axial magnetic field, explainable only
by means of the generation of an internal azimuthal current, have been contemporaneously
detected with the other signs of wave-conversion. This drift
motion accords totally with theoretical Golovanivsky predictions.
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Agostinetti, Piero. "Methods for the Thermo-mechanical Analysis and Design of High Power Ion Sources." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425025.
Full textAbstract:
The present doctorate thesis regards the major issues related to the thermo-mechanical analysis and design of high power ion sources. The activities were carried out in the following three areas:
1. Experimental activities on the existing ion sources.
2. Evaluation of the main operating parameters (plasma density, heat loads etc.) of the ITER Neutral Beam Injector (NBI) ion source.
3. Optimization of the thermo-mechanical design of the ITER NBI ion source, considering both the point of views of a good operating behaviour (in terms of ion current density and electrons-to-ions ratio) and a good reliability of the machine (in terms of structural verifications, low deformations and ability to control the operating parameters).
The main original contributions in the three fields have been respectively:
1. A new method for the post-processing of the calorimetric measurement on an ion source, able to precisely evaluate the heating power loads deposed on the various components of the ion source.
2. A new method for the evaluation of the damages given by sputtering inside an ion source.
3. A new Finite Element Method (FEM) technique especially developed for high performance cooling systems, that integrates non-linear CFD, thermal and structural analysis.
Moreover, the following themes, related to the analysis and design of a generic mechanical component, have been investigated and applied to the ion sources:
* The Decision Making methods, with a comparison between the main approaches and an application on the accelerator cooling system design.
* The Computational Fluid Dynamics analyses, with a comparison between the most sophisticated approaches, analytical formulas and experimental data, and an application to the ITER Neutral Beam Injector design.
* The Buckling analyses, with a comparison between different analytical and numerical approaches for the calculation of the buckling modes of a structure subjected to external pressure, and an application to the vacuum vessel of the ELISE facility.
The methods described on this doctorate thesis were developed during the design activities for the ITER Neutral Beam Test Facility at Consorzio RFX (Padova, Italy) and for the ELISE Facility at the Max-Planck-Institut für Plasmaphysik (Garching, Germany), supported by the European Communities under contracts of Association between EURATOM and ENEA, and carried out within the framework of the European Fusion Development Agreement.
Most of these methods can be used also for the analysis and design of a generic high heat flux component. In particular, they are suitable for the analysis and design of many components for the ITER experiment, for the demonstrative reactor DEMO and for the future commercial fusion reactors.
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Lawrie, Scott. "Understanding the plasma and improving extraction of the ISIS Penning H⁻ ions source." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:1648761a-57b1-4d6f-8281-9d1c36ccd46a.
Full textAbstract:
A Penning-type surface-plasma negative hydrogen (H-) ion source has been delivering beam at the ISIS pulsed spallation neutron and muon facility for over thirty years. It is one of the most powerful and well-renowned H- sources in the world. Although long-term experience has allowed the source to be operated reliably and set up in a repeatable way, it is treated as something of a 'black box': the detailed plasma physics of why it works has always been unclear. A vacuum Vessel for Extraction and Source Plasma Analyses (VESPA) has been developed to understand the ISIS ion source plasma and improve the beam extracted from it. The VESPA ion source is operated in a completely new regime whereby the analysing sector dipole magnet housed inside a refrigerated 'cold box', presently used on ISIS, is replaced by an on-axis extraction system. The new extraction system incorporates a novel einzel lens with an elliptical aperture. This is the first demonstration of an elliptical einzel being used to focus an asymmetric H- ion beam. With the dipole magnet removed, the ion source has been shown to produce 85 mA of H- beam current at normal settings; of which 80 mA is transported through the new einzel lens system, with a normalised RMS emittance of 0.2 π mm mrad. Optical emission spectroscopy measurements have shown a plasma density of 1019 mâ3, an H2 dissociation rate of 70%, an almost constant electron temperature of 3.5 eV and an atomic temperature which linearly increases above the electron temperature. In support of these principal measurements, rigorous particle tracking, electrostatic and thermal simulations were performed. In addition, a suite of new equipment was manufactured by the author. This includes a fast pressure gauge, a temperature controller, a high voltage einzel lens circuit, a fast beam chopper and a caesium detection system.
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Gerst, Jan Dennis. "Investigation of magnetized radio frequency plasma sources for electric space propulsion." Phd thesis, Université d'Orléans, 2013. http://tel.archives-ouvertes.fr/tel-00977801.
Full textAbstract:
The PEGASES thruster (Plasma Propulsion with Electronegative Gases) is a novel type of electric thruster for space propulsion. It uses negative and positive ions produced by an inductively coupled radio frequency discharge to create the thrust by electrostatically accelerating the ions through a set of grids. A magnetic filter is used to increase the amount of negative ions in the cavity of the thruster. The PEGASES thruster is not only a source to create a strongly negative ion plasma or even an ion-ion plasma but it can also be used as a classical ion thruster. This means that a plasma is created and only the positive ions are extracted and accelerated making it necessary to neutralize the plasma behind the acceleration stage like in other ion thrusters. The performances of the PEGASES thruster have been investigated mainly in xenon in order to compare the obtained results with RIT-type ion thrusters. The thruster has been investigated with the help of a variety of probes such as a Langmuir probe, a planar probe, a capacitive probe and a RPA (Retarding Potential Analyzer). In addition, an ExB probe has been developed to measure the velocity of the ions leaving the thruster and to differentiate between the ion species present in the plasma.
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Chen, Li. "Fabrication of electron sources for a miniature scanning electron microscope." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313904.
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Densham, Christopher John. "Design and development of a tantalum foil target for the production of high intensity radioactive beams." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365727.
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Stins, O. W. M. "A Retarding Field Energy Analyser to measure the Energy Distributions of Liquid Metal Ion Sources." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-32306.
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Kim, George E. (George Ea-Hwan). "The effects of low pressure nitrogen on titanium cathode sources in TiN arc ion-plating." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29062.
Full textAbstract:
The arc ion-plating technique is used in the industrial coating processes where TiN thin films are deposited onto various base materials. The overall objective of this research was to study the effects of low pressure nitrogen introduced into a continuous, titanium vacuum arc. An arc ion-plating system was designed and built to allow for as much flexibility as possible. Permanent magnets were placed behind the cathode surface to confine and rotate the arc.Changes in cathode, arc and emission properties were noted with respect to vacuum, argon and nitrogen ambients. The introduction of nitrogen, above a critical pressure ($ sim$1 $ times 10 sp{-3}$ Torr), increased arc velocity and decreased crater diameter, erosion rate and ion emission. This occurred when arc rotation was combined with nitrogen introduction. Thermal properties of the cathode during arcing seemed to play an important role in determining the extent of nitrogen-cathode interaction. X-ray photoelectron spectroscopy (XPS) analysis has shown that nitriding occurred within the regions of arcing and was dependent on nitrogen pressure (with all other parameters remaining constant). The most encouraging result found was the complete elimination or macroparticles normally present in the coating/film.
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Rauner, David [Verfasser], and Ursel [Akademischer Betreuer] Fantz. "Efficiency of RF plasma generation for fusion relevant ion sources / David Rauner ; Betreuer: Ursel Fantz." Augsburg : Universität Augsburg, 2019. http://d-nb.info/1181693330/34.
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Gauter, Sven [Verfasser]. "Calorimetric investigation on plasma and ion beam sources used for thin film deposition / Sven Gauter." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1168229146/34.
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Stins, O. W. M. "A Retarding Field Energy Analyser to measure the Energy Distributions of Liquid Metal Ion Sources." Forschungszentrum Rossendorf, 1994. https://hzdr.qucosa.de/id/qucosa%3A22057.
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Castro, Olivier de. "Development of a Versatile High-Brightness Electron Impact Ion Source for Nano-Machining, Nano-Imaging and Nano-Analysis." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS468/document.
Full textAbstract:
Les nano-applications utilisant des faisceaux d'ions focalisés nécessitent des sources d'ions à haute brillance avec une faible dispersion en énergie (ΔE) ce qui permet une excellente résolution latérale et un courant d'ions suffisamment élevé pour induire des vitesses d'érosion raisonnables et des rendements élevés d'émission électronique et ionique. Les objectifs de cette thèse sont le développement d'une source d'ions basée sur l'impact électronique ayant une brillance réduite Br de 10³ – 10⁴ A m⁻² sr ⁻ ¹ V⁻ ¹, une dispersion en énergie ΔE ≲ 1 eV et un choix polyvalent d'ions. Le premier concept évalué consiste à focaliser un faisceau d'électrons à une énergie de 1 keV entre deux électrodes parallèles distant de moins d'un millimètre. Le volume d'ionisation « micrométrique » est formé au-dessus d'une ouverture d'extraction de quelques dizaines de µm. En utilisant un émetteur d'électrons LaB₆ et une pression de 0.1 mbar dans la région d'ionisation, Br est proche de 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ avec des tailles de source de quelques µm, des courants de quelques nA pour Ar⁺/Xe⁺/O₂ ⁺ et une dispersion en énergie ΔE < 0.5 eV. La brillance réduite Br est encore en dessous de la valeur minimum de notre objectif et la pression de fonctionnement très faible nécessaire pour l'émetteur LaB₆ ne peut être obtenue avec une colonne d'électrons compacte, donc ce prototype n'a pas été construit.Le deuxième concept de source d'ions évalué est basé sur l’idée d’obtenir un faisceau ionique à fort courant avec une taille de source et un demi-angle d’ouverture similaire aux résultats du premier concept de source, mais en changeant l’interaction électron-gaz et la collection des ions. Des études théoriques et expérimentales sont utilisées pour l’évaluation de la performance de ce deuxième concept et de son utilité pour les nano-applications basées sur des faisceaux d'ions focalisésHigh brightness low energy spread (ΔE) ion sources are needed for focused ion beam nano-applications in order to get a high lateral resolution while having sufficiently high ion beam currents to obtain reasonable erosion rates and large secondary electron/ion yields. The objectives of this thesis are: the design of an electron impact ion source, a reduced brightness Br of 10³ – 10⁴ A m⁻² sr⁻ ¹ V⁻ ¹ with an energy distribution spread ΔE ≲ 1 eV and a versatile ion species choice. In a first evaluated concept an electron beam is focussed in between two parallel plates spaced by ≲1 mm. A micron sized ionisation volume is created above an extraction aperture of a few tens of µm. By using a LaB₆ electron emitter and the ionisation region with a pressure around 0.1 mbar, Br is close to 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ with source sizes of a few µm, ionic currents of a few nA for Ar⁺/Xe⁺/O₂ ⁺ and the energy spread being ΔE < 0.5 eV. The determined Br value is still below the minimum targeted value and furthermore the main difficulty is that the needed operation pressure for the LaB₆ emitter cannot be achieved across the compact electron column and therefore a prototype has not been constructed. The second evaluated source concept is based on the idea to obtain a high current ion beam having a source size and half-opening beam angle similar to the first concept, but changing the electron gas interaction and the ion collection. Theoretical and experimental studies are used to evaluate the performance of this second source concept and its usefulness for focused ion beam nano-applications
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Haas, Raphael [Verfasser]. "Tailor-made thin radionuclide layers for targets and recoil ion sources in nuclear applications / Raphael Haas." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2020. http://d-nb.info/1223379051/34.
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Maimone, Fabio Antonio. "Investigation on the Microwave-based techniques to improve the performances of the Electron Cyclotron Resonance Ion Sources." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1016.
Full textAbstract:
Le sorgenti di ioni di tipo ECR (Electron Cyclotron Resonance) si sono rivelate molto importanti per la produzione continua ed affidabile di fasci intensi di ioni ad alto stato di carica destinati alle facilities di acceleratori di particelle. Recentemente, nuove tecniche sono state sviluppate per migliorare le prestazioni delle sorgenti ioniche esistenti e di quelle in fase di sviluppo. La variazione della frequenza delle microonde e l iniezione di due onde elettromagnetiche a frequenza diversa nella sorgente di ioni sono due aspetti importanti per tale miglioramento. Queste tecniche, basate sulle diverse distribuzioni di campo elettromagnetico che possono essere eccitate dentro una sorgente ECR e sul miglioramento dell accoppiamento a microonde tra le onde elettromagnetiche e il plasma magneticamente confinato, sono state analizzate in questa tesi. Abbiamo condotto la maggior parte degli esperimenti con la sorgente ECR CAPRICE istallata al GSI Helmholtzzentrum fuer Schwerionenforschung GmbH e i risultati conseguiti si sono rivelati importanti sia dal punto di vista scientifico che per lo sviluppo di nuove sorgenti ECR. Le analisi teoriche e sperimentali presentate con questo lavoro di tesi hanno fornito infatti utili spiegazioni sull aumento delle prestazioni di tali sorgenti di ioni in termini di produzione di fasci più intensi di ioni a più alto stato di carica.
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Henares, González Jose. "Study of condensable ion production by resonant laser ionization." Caen, 2016. http://hal.in2p3.fr/tel-01314260.
Full textAbstract:
Cette thèse doctorale décrit le développement d´une source d´ions par ionisation laser résonante (RILIS) à GANIL. RILIS est une technique sélective de production d´ions qui est basé sur un procédé d'excitation résonante par étapes dans lequel les éléments d'intérêt sont ionisés via l´excitation de résonance atomique par le rayonnement des lasers titan:saphir. Le banc de test RILIS à GANIL consiste en trois lasers titan:saphir et une source d´ions (cavité chaude). Dans cette thèse, un nouveau schème d´ionisation a été développé pour Zn et les schèmes d'ionisation déjà connues pour Sn ont été comparés afin de déterminer le meilleur schéma d'ionisation pour un système laser titan:saphir. D´ailleurs, plusieurs configurations de la géométrie de la source d'ions ont été testés (deux diamètres et deux longueurs) afin de trouver une efficacité d´ionisation et emittance optimales. L´incrément du diamètre a produit une amélioration de la production d´ions laser, par contre aucun changement n’a été observé en modifiant la longueur. Le temps de vol des faisceaux d´ions ont été aussi étudiés pour les différentes configurations à plusieurs températures. Le temps de vol peut proportionner information sur la formation des ions à l´intérieure du corps de source. En autre, une technique pour mesurer la convolution de l´écart spatiale et énergétique du faisceau d´ions a été développé. Finalement, deux techniques ont été testées pour réduire la contamination : En première lieu, le mouvement des ions à travers la source d´ions peut être modifié par le champ électrique, provenant de l´effet Joule. Par conséquent, une étude de la configuration plus approprie a été effectué pour réduire la contamination des faisceaux d´ions par des alcalins. Deuxième, un matériau avec basse travail de sortie a été testé pour réduire la production des contaminants alcalins dans la source d´ionsThis doctoral thesis describes the development of a Resonant Ionization Laser Ion Source (RILIS) at the GANIL facility. The RILIS is a selective ion source technique which is based on a step-wise resonant excitation process where the elements of interest are ionized via atomic resonant excitation by laser radiation. The off-line RILIS test bench at GANIL consists of three tunable titanium:sapphire lasers and a hot-cavity ion source. In this thesis, a new three-step Zn ionization scheme was developed and the already known ionization schemes for Sn have been compared in order to identify the best ionization scheme for titanium:sapphire laser systems. Furthermore, several configurations of the ion source geometry were tested (two diameters and two lengths) in order to provide an optimal ionization efficiency and ion beam emittance. An increasing of the ionizer diameter was found to enhance the production of laser ionizer elements, while no enhancement was observed by modifying the ionizer length. The time-of-flight of the generated ions was also studied for the different ion source configurations at several temperatures. The time-of-flight can provide information about the ion formation inside the ion source cavity. In addition, a technique to measure the convolution of the spatial and energetic spread of the ion bunches at the detection point was developed. Finally, two contamination reduction techniques were studied: Firstly, the ions trajectories through the ion source cavity can be modified by the electric field generated due to resistive heating. Therefore, a study of the appropriate configuration of the electric field direction was performed to reduce the alkali contamination of the ion beam. Secondly, a low work function material was tested in order to reduce the production of alkali contaminants and molecular sidebands generated inside the ion source
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Zekavat, Behrooz. "Experimental and Theoretical Approaches for Wide Mass Range Biomarker Discovery Using Fourier Transform-Ion Cyclotron Resonance (FT-ICR) Mass Spectrometers Coupled to External Ion Sources." Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/ZekavatB2011.pdf.
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Leleu, Olivier. "Étude du métabolisme azoté du colza : régulation de l'activité nitrate réductase en fonction du développement et des sources azotées." Lille 1, 2000. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2000/50376-2000-306.pdf.
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L'etude d'un cycle complet de developpement chez le colza a montre qu'il existait un fort potentiel de reduction du nitrate au moment de la reprise de la croissance au printemps. Au moment de l'initiation de la floraison, la reduction du nitrate se delocalise des feuilles vers les tiges et enfin vers les siliques. Une telle capacite des siliques a reduire le nitrate constitue une originalite. Par ailleurs, nous avons mis en evidence que la dynamique de la biomasse foliaire, croissance et senescence, est un facteur cle de l'efficacite d'utilisation de l'azote (leleu et al. 2000, plant biology and biochemistry 2000 38 : 639-645). Des plantules de colza cultivees in vitro presentent dans leur partie aerienne (cotyledons et hypocotyle), une activite nitrate reductase (anr) independante de la source d'azote. Quand l'ammonium constitue la seule source d'azote disponible pour le colza, l'anr est fortement augmentee par rapport a celle obtenue en presence de nitrate. Le taux de transcrits nitrate reductase (nr) et le contenu en proteine nr sont egalement augmentes. Cette regulation particuliere se trouve dans les cotyledons aussi bien en presence d'ammonium qu'en absence totale d'azote. L'anr semble proportionnelle au contenu endogene en ammonium. L'assimilation de l'ammonium et la production de glutamate puis de glutamine paraissent avoir un role fondamental dans la regulation de l'anr des parties aeriennes de plantules de colza. C'est la premiere fois que l'on montre une telle deregulation de la nr en presence d'un stress ammoniacal. L'elucidation des voies metaboliques en cause pourrait apporter des idees nouvelles quant a la regulation de la nr en conditions naturelles.
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Hémery, Charles-Victor. "Etudes des phénomènes thermiques dans les batteries Li-ion." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00968666.
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Les travaux présentés dans cette thèse concernent l'étude thermique des batteries Li-ion en vue d'une application de gestion thermique pour l'automobile. La compréhension des phénomènes thermiques à l'échelle accumulateur est indispensable avant de réaliser une approche de type module ou pack batterie. Ces phénomènes thermiques sont mis en évidence à partir d'une modélisation thermique globale de deux accumulateurs de différentes chimies, en décharge à courant constant. La complexité du caractère résistif de l'accumulateur Li-ion a mené au développement d'un modèle prenant en compte l'interaction entre les phénomènes électrochimiques et thermiques, permettant une approche prédictive de son comportement. Enfin la réalisation de deux boucles expérimentales, de simulation de systèmes de gestion thermique d'un module de batterie, montre les limites d'un refroidissement classique par air à respecter les critères de management thermique. En comparaison, le second système basé sur l'intégration innovante d'un matériau à changement de phase (MCP) se montre performant lors de situations usuelles, de défauts ou encore lors du besoin d'une charge rapide de la batterie.
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Mhibik, Oussama. "Développement des sources lasers solides continues, visibles et stabilisées en fréquence : une alternative aux lasers à colorants." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00656426.
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Le traitement de l'information quantique, en particulier celui utilisant les centres colorés du diamant et la manipulation cohérente des ions de terre rare incorporés dans des matrices solides (Pr3+, Eu3+) et la spectroscopie à ultra-haute résolution, nécessitent des sources accordables ayant une faible largeur de raie. Or, dans la gamme rouge-orange (570-635 nm) où les diodes lasers font défaut et les lasers solides restent très peu développés, les lasers à colorants sont actuellement les seules sources de rayonnement cohérent disponibles. En revanche, ce type de laser est assez complexe et difficile à stabiliser au niveau du kHz à cause des bruits à haute fréquence générés par le jet de colorant.Pour répondre aux besoins des expériences citées ci-dessus, cette thèse vise à proposer une alternative "tout solide" aux lasers à colorants en explorant différentes possibilités pour la construction d'une source stable émettant dans l'orange-rouge. Dans ce but, nous avons proposé deux solutions:1. La première consiste à développer des oscillateurs paramétriques optiques. Dans cette voie, nous avons développé un OPO simplement résonant à doublage de fréquence intra-cavité et stabilisé en frequence au niveau du kHz.2. La deuxième consiste en un laser à base de fluorures dopés au Pr3+pompé par diode.
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Lopez, Colin. "Développement de sources haute-résolution de particules chargées grâce au contrôle de leur trajectoire par corrélation temps-position." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASP013.
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L’objet de cette thèse consiste en un développement de sources de particules chargées (ions ou électrons) dont la résolution en énergie, position et temps approchent les limites permises par les lois physiques. Le principe est d’utiliser la détection sensible en temps et position pour l’une des deux particules chargées corrélées, produites par photoionisation d’un nuage d’atomes froids, pour corriger en temps réel la trajectoire 3D de la particule partenaire afin d’en maîtriser le plus finement possible les caractéristiques spatio-temporelles. Le projet a pour but de créer, à partir de l’ionisation d’atomes de césium refroidis par laser, un nouveau type de source d’ions et d’électrons permettant une meilleure focalisation des faisceaux. Ce travail permet d’envisager de nouvelles expériences basées sur le contrôle de particules chargées uniques et ainsi de s’affranchir des effets de répulsion coulombienne dégradant les sources actuelles.Le but ultime étant d’arriver à déposer sur une surface un ion ou un électron avec des caractéristiques de vitesse, de position et de temps d’une précision jamais atteinte jusque-là. Des applications évidentes en implantation d’ions sont envisagées (lithographie). Les potentialités de ce dispositif en termes de correction de trajectoire ouvrent la voie d’un contrôle total du temps, de la position et de la vitesse d’arrivée des ions sur la cible. Une augmentation du flux est déjà envisagée, en vue d’application d’imagerie, en améliorant la vitesse de traitement en temps réel des informations temps/position des électrons.Le projet présenté ici s’inscrit désormais dans un projet plus vaste : une source d’ions basée sur ce principe est en cours d’étude avec la société Orsay Physics spécialisée dans la conception et la fabrication de colonnes à faisceaux d’ions focalisés (FIB)The topic of this thesis is the development of charged particle sources (ions or electrons) whose energy resolution, position and time approach the limits permitted by physic laws. The idea is to use the sensitive detection in time and position for one of the two correlated charged particles produced by the photoionization of an cold atoms cloud, to correct in real time the 3D trajectory of the particle partner to know as thinly as possible its spatiotemporal characteristics. The project aims to create, from the ionization of cesium atoms cooled by laser, a new type of ion or electron source allowing a better beam. We can now consider new experiences based on the unique control of charged particles and thus overpass the Coulomb repulsion effects that degrades the common sources.The ultimate goal is to be able to depose an ion or an electron on a surface with the speed, position and time characteristics never reached. Some applications in ions implantation are expected (lithography). In terms of trajectory correction it could allow a full control of time, position and velocity of ions reaching the target. A further increase of the flow is already considered for purposes of imaging (real-time processing of time-position data). The project presented here is now part of a larger project: an ion source based on this concept is under study with the Orsay Physics Company specialized in the design and manufacture of columns Focused ion beam (FIB)
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Hujňák, Jan. "Studie materiálů pro Li-ion akumulátory pomocí elektronové mikroskopie." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413237.
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This work deals with problems of lithium-ion batteries. In the theoretical part are described electrochemical sources in general and their division. The main representatives of individual types of electrochemical sources are described in more detail. In the next part the thesis focuses specifically on lithium-ion accumulators, their history, electrochemical reactions taking place inside and materials of individual parts of which the accumulator consists. Next part focuses on electron microscopy and its division into scanning and transmission. Basic parts and the principle of operation are described. The practical part is focused on creating a small cell for examination under an electron microscope.
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Wagner, Sasha. "Black Carbon: Sources, Mobility and Fate in Freshwater Systems." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2213.
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Black carbon (BC) is a complex mixture of polycondensed aromatic compounds produced by the incomplete combustion of biomass during events such as wildfires and the burning of fossil fuels. Black carbon was initially considered to be a refractory form of organic matter. However, recent studies have shown that BC can be quite mobile and reactive in the terrestrial environment. Black carbon can be translocated from soils and sediments in the form of dissolved BC (DBC). A global correlation between DBC and bulk dissolved organic carbon (DOC) has been established for fluvial systems where DBC comprises approximately 10% of the total DOC pool, which suggests that DBC may be a significant contributor to the global carbon cycle.
The primary objective of this thesis was to further characterize DBC and elucidate some of the specific physical and chemical processes that promote its transfer to the aqueous phase and drive the DBC-DOC relationship. The molecular composition and qualitative distribution of DBC was assessed using Fourier transform ion cyclotron resonance mass spectrometry. Black carbon in both dissolved and particulate (PBC) phases was quantified by the benzenepolycarboxylic acid method. Dissolved BC was found to contain considerable amounts of nitrogen and the export of this dissolved black nitrogen was linked to watershed land use in global rivers. The riverine flux of PBC, a previously unstudied BC removal mechanism, was significantly increased by local wildfire activity. However in-stream DBC did not appear to be affected by short-term fire events. Once translocated to surface waters, DBC is susceptible to photodegradative processes. Dissolved BC in high molecular weight DOC fractions was more photoreactive than DBC associated with lower molecular weight fractions.
In the coming decades, wildfire frequency is expected to increase with climate change and natural lands will continue to be altered for anthropogenic use. These processes have already been shown to significantly impact the composition of DOC and associated DBC exported to inland waters. The quality of DBC influences its stability in soil and resistance to degradation. Therefore, it is essential that we aim to fully understand DBC dynamics in natural systems in order to assess its contribution to global carbon cycling.
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Legrand, Nathalie. "Modèle multiphysique et méthodes d'analyse in-situ, non destructives, qualitatives et quantitatives de diverses sources de vieillissement d'accumulateurs lithium-ion." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0240.
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L'optimisation de la durée de vie d'une batterie nécessite la prédiction de son vieillissement et donc l'identification des mécanismes de vieillissement qui en sont à l'origine. Pour pallier les limitations des outils de caractérisation du vieillissement classiquement utilisés (mesures intermittentes de performance au cours du vieillissement et tests de caractérisation post-mortem), des outils d'étude non destructive de l'état des électrodes en cours de vie ont été mis au point et testés. Il s'agit d'un modèle multiphysique de fonctionnement de la batterie lithium-ion et de deux méthodes d'extraction de paramètres in-situ : la première basée sur le traitement de la dérivée du profil de tension et la seconde sur la différence des pentes de profils de tension entre l'état neuf et l'état considéré. Les paramètres non disponibles mais nécessaires à l'établissement du modèle multiphysique d'un élément ont été estimés pour différents états de charge et différentes températures. Ce modèle a été validé par comparaison avec des mesures expérimentales. L'application de ces outils est illustrée dans le cas de trois mécanismes de vieillissement différents. En outre, ces outils ont été plus particulièrement appliqués au vieillissement par dépôt de lithium. L'utilisation du modèle de l'élément commercial VL41M Saft a permis de dresser un abaque de ses courants limites de fonctionnement et a fait l'objet d'une validation expérimentale mettant en oeuvre la méthode dite de la dérivéeOptimisation of a battery life time requires the prediction of its ageing and the identification of the involved ageing mechanisms. In order to avoid the limitations due to standard ageing characterisation methods (performance evaluations conducted regularly along ageing and post-mortem characterisations), other tools allowing assessment of the electrode state without deterioration along the life time, have been tested. It concerns a multiphysic model of lithium-ion battery and two methods for in-situ parameter extraction: the first is based on the study of the derivative of the tension profile and the second one, on the difference between the slope of the tension profiles at the fresh state and at the considered state. The non-available parameters required for set up of the multiphysic model for one battery have been evaluated for different states of charge and various temperatures. This model has been validated by comparison with experimental measurements. The application of these tools is illustrated for three different ageing mechanisms. Moreover these methods have been especially applied for the case of lithium plating ageing. Use of the VL41M Saft model allowed to set up an abacus of the limiting charge currents and an experimental validation has been performed in using the method so-called derivation method
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Oudini, Noureddine. "Modélisation d'une source d'ions à effet Hall pour des applications de traitement de surface." Phd thesis, Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1368/.
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Dans les sources d'ions de type EHIS " End-Hall Ion Source " un faisceau ionique est extrait d'un plasma magnétisé sans l'utilisation d'un système de grilles d'extraction. Les sources EHIS sont essentiellement utilisées dans des procédés de traitement de surface. Dans ce type de sources, le plasma est généré par l'application d'une tension entre les électrodes afin de créer une décharge DC. La présence, dans le plasma, d'un champ magnétique parallèle à une anode conique réduit la mobilité électronique dans la direction perpendiculaire aux lignes de champ magnétique. La chute de conductivité électronique dû au champ magnétique près de l'anode entraîne l'établissement d'un champ électrique dans cette région pour assurer le transport du courant électronique vers l'anode. Les ions créés par impact électron-atome sont expulsés de la source par le champ électrique proche de l'anode et forment un faisceau ionique. Ces sources ont été optimisées de façon très empirique et leur fonctionnement est loin d'être totalement compris. Dans le but de mieux comprendre le mécanisme de fonctionnement des sources EHIS, nous avons développé un modèle auto-cohérent axisymétrique. Dans ce modèle les espèces lourdes (Ar et Ar+) sont décrites de façon particulaire. Le transport électronique est traité de façon fluide par résolution des trois premiers moments de l'équation de Boltzmann en supposant l'équilibre de Boltzmann le long des lignes de champ magnétique et la quasi-neutralité du plasma. Le champ électrique est déduit d'une équation de conservation du courant. Ce model a permis de clarifier plusieurs aspects du fonctionnement des " End-Hall Ion Sources "In End-Hall Ion Source (EHIS) an ion beam is extracted from a magnetized plasma without extracting grids. The EHIS sources are mainly used in surface processing technology. In these sources, the plasma is generated by applying an external voltage between the electrodes in order to create a DC discharge. The presence of a magnetic field parallel to a conical anode reduces the electron mobility across the magnetic field lines. As a consequence, an electric field forms in the anode region of the plasma in order to insure electron transport towards the anode. Ions are generated inside the EHIS by electron impact ionization of the injected argon atoms, are extracted from the source by the electric field formed along the anode, and form an ion beam which is used in different surface processing applications. The End-Hall Ion Sources have been optimized empirically and the physics of these sources is far from being clearly understood. In order to improve our understanding of the EHIS operation, we have developed an axisymmetric self-consistent model based on a particle description of argon atoms and ions, and on a fluid model of electron transport. Electrons are supposed to be in Boltzmann equilibrium along the magnetic field lines and plasma quasi-neutrality is assumed. The electric field is therefore obtained from a current continuity equation and not from Poisson equation. The model has been able reproduce most of the features of the source and has helped clarifying a number of questions related to the physics of EHIS
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Karlsson, Ulrika. "Environmental levels of thallium : Influence of redox properties and anthropogenic sources." Doctoral thesis, Örebro : Örebro universitetsbibliotek, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-356.
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