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 succès. / The 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.

This study produced and analyzed shaped tungsten wire tips formed through electrochemical etching. Specifically, the cone length and the radius of curvature of the tip were analyzed. Having the tips move dynamically through an electrolytic solution, such as potassium hydroxide, and tuning the initial starting depth of the tungsten wire along with the dynamic speed of the tungsten wire as it passed throughout the solution allowed various types of tip profiles to be produced. The tip's radius of curvature was able to be reproduced with an accuracy between 88 - 92 %. The method provided would be applicable for the production of various styles of liquid-metal ion source (LMIS) probes and scanning probe microscope (SPM) tips.

We have designed a new type of plasma gun ion source for a Malmberg-Penning trap based on Metal Vapor Vacuum Arc (MeVVA) ion source designs. Our primary intent with this MeVVA-type source is to create a confinable beryllium-7 (7-Be) plasma. 7-Be is a peculiar isotope due to its varying radioactive decay half-life in different electro-chemical configurations. It is also found in an unexpected abundance at high altitudes of the Earth's atmosphere. It is possible ioniziation affects the radioactivity of the isotope, partly explaining this discrepancy with atmospheric models. The short half-life of 7-Be requires us to replace the sample inside the ion source on a regular basis. Our design makes it possible to easily remove the cathode of the ion source from an ultra-high vacuum trap and exchange 7-Be samples while only needing to repressurize a small chamber rather than the entire trap. This design has an added benefit of being capable of generating plasmas from a wide variety of metals by simply exchanging the source target in the removable cathode. Because of this wide compatibility, we will be able to use our trap for studying any number of different plasmas, including other radioactive types. Testing of the ion source design shows we are able to extract more than a sufficient number of ions at reasonable energies for confinement.

A system is presented that is capable of confining an ion beam or plasma within a region that is essentially free of applied fields. An Artificially Structured Boundary (ASB) produces a spatially periodic set of magnetic field cusps that provides charged particle confinement. Electrostatic plugging of the magnetic field cusps enhances confinement. An ASB that has a small spatial period, compared to the dimensions of a confined plasma, generates electro- magneto-static fields with a short range. An ASB-lined volume thus constructed creates an effectively field free region near its center. It is assumed that a non-neutral plasma confined within such a volume relaxes to a Maxwell-Boltzmann distribution. Space charge based confinement of a second species of charged particles is envisioned, where the second species is confined by the space charge of the first non-neutral plasma species. An electron plasma confined within an ASB-lined volume can potentially provide confinement of a positive ion beam or positive ion plasma. Experimental as well as computational results are presented in which a plasma or charged particle beam interact with the electro- magneto-static fields generated by an ASB. A theoretical model is analyzed and solved via self-consistent computational methods to determine the behavior and equilibrium conditions of a relaxed plasma. The equilibrium conditions of a relaxed two species plasma are also computed. In such a scenario, space charge based electrostatic confinement is predicted to occur where a second plasma species is confined by the space charge of the first plasma species. An experimental apparatus with cylindrical symmetry that has its interior surface lined with an ASB is presented. This system was developed by using a simulation of the electro- magneto-static fields present within the trap to guide mechanical design. The construction of the full experimental apparatus is discussed. Experimental results that show the characteristics of electron beam transmission through the experimental apparatus are presented. A description of the experimental hardware and software used for trapping a charged particle beam or plasma is also presented.

Le développement de la source d'ions négatifs pour l’injecteur de particules d’ITER constitue une des étapes essentielles pour générer des neutres de haute énergie . Pour remplir les caractéristiques requises pour ITER en termes de chauffage et de courant à l'intérieur du réacteur principal, la source d'ions négatifs doit délivrer 40A de D-. La création d'une telle source représente un défi tant technique que scientifique et demande une meilleure compréhension des phénomènes physiques impliquées . Les connaissances actuelles sur le méchanisme d'extraction d'ion négatifs d’un plasma électronégatif sont limitées, spécialement concernant la compréhension des caractéristiques d'une gaine de plasma magnétisé dans la région d’intérêt où on constante également l’extraction des électrons simultanément avec les ions négatifs qui. De plus, l'asymétrie due à la configuration croisée du champ magnétique pour piéger les électrons nécessite une étude du problème en trois dimensions. Un code 3D Particle-In-Cell électrostatique a été spécialement développé pour étudier ce problème. Le code utilise les coordonnées cartésiennes et peut prendre en compte des géométries complexes. Le code nommé ONIX étudie les propriétés du plasma et le transport des électrons et des ions négatifs au niveau de la zone d'extraction. Les résultats sur la formation d'un ménisque de plasma et l'écrantage du champ d'extraction par ce plasma, ainsi que les trajectoires des ions négatifs, sont présentés. L'efficacité de l'extraction d'ions négatifs du volume et de la surface est investiguée et on trouve que les processus de création en surface des ions négatifs jouent un rôle capital. / The development of the negative ion source constitutes a crucial step in the construction of the neutral beam injector of ITER. To fulfil the ITER requirements in terms of heating and current drive, the negative ion source should deliver 40 A of D-. The achievement of such a source is challenging from technical and scientific points, and it requires a deeper understanding of the underlying physics. The present knowledge of the ion extraction mechanism from the negative ion source is limited due to the complexity of the problem that involves the comprehension of the behaviour of magnetized plasma sheaths when negative ions and electrons are pulled out from the plasma. Moreover, due to the asymmetry induced by the crossed magnetic configuration used to filter the electrons, any realistic study of this problem must consider the three spatial dimensions. To address this problem in a realistic way, a 3D Particles-in-Cell electrostatic code specifically designed for this system was developed. The code uses Cartesian coordinate system and it can deal with complex boundary geometry as it is the case of the extraction apertures. The complex magnetic field that is applied to deflect electrons is also taken into account. This code, called ONIX, was used to investigate the plasma properties and the transport of negative ions and electrons close to a source extraction aperture. Results on the formation of the plasma meniscus and the screening of the extraction field by the plasma are presented here, as well as negative ions trajectories. Negative ion extraction efficiency from volume and surfaces was investigated showing the capital importance of the surface negative ion production.

This thesis is about the designing and constructing a microwave ion source. The ions are generated in a thermal and dense hydrogen plasma by microwave induction. The plasma is generated by using a microwave source with a frequency of 2.45 GHz and a power of 700 W. The generated microwave is pulsing with a frequency of 50 Hz. The designed and constructed microwave system generates hydrogen plasma in a pyrex plasma chamber. Moreover, an ion extraction unit is designed and constructed in order to extract the ions from the generated hydrogen plasma. The ion beam extraction is achieved and ion currents are measured. Th e plasma parameters are determined by a double Langmuir probe and the ion current is measured by a Faraday cup. The designed ion extraction unit is simulated by using the dimensions of the designed and constructed ion extraction unit in order to trace out the trajectories of the extracted ions.

Depuis leur découverte dans divers environnements astrophysiques, les anions polyyne CxH¯ (x = 2, 4, 6) et les anions cyanopolyyne CxN¯ (x = 1, 3, 5) ont reçu une attention considérable. Ces anions semblent jouer des rôles importants dans leur environnement. Cependant, les données à basse température sur les voies chimiques menant à leur formation et à leur destruction sont encore rares, en particulier ce qui concerne l'identité du produit et les ratios de ramification. Pour résoudre ce problème, nous nous sommes engagés dans la recherche de la réactivité de ces anions moléculaires en utilisant des instruments dédiés couplant des jets subsonique et supersonique avec des méthodes de spectrométrie de masse. De cette façon, nous avons étudié la réactivité des anions C3N avec le cyanoacétylène (HC3N) ainsi que la réactivité de CN¯, C3N¯, et C5N¯ avec l'acide formique (HCOOH) de 298 K à des températures aussi basses que 36 K. Nous rapportons dans ce travail le taux de vitesse, les produits, et les ratios de ramification de ces réactions. Ce travail aborde également la source prototype d'ions sélectionnée, qui a récemment été mis en place dans notre laboratoire afin d'étendre notre recherche à d'autres anions d'intérêt astrophysique (e.g. les anions CxH¯ et Cx¯). Une description de cet instrument ainsi que des résultats préliminaires sont présentés dans ce travail. Cette thèse, «Reactivity of Molecular Anions at Low Temperature: Implications for the Chemistry of the Interstellar medium and Titan’s atmosphere», a été réalisée au sein de l'Institut de physique de Rennes et de l'Ecole Nationale Supérieure de Chimie de Rennes. Mots-clés: astrochimie, atmosphère de Titan, anions moléculaires, cinétique en phase gazeuse, jet supersonique, spectrométrie de masse, source d’ions sélectionnée / Ever since their discovery in various astrophysical environments, polyyne anions CxH¯ (x = 2, 4, 6) and cyanopolyyne anions CxN¯ (x = 1, 3, 5) have received a considerable attention. These anions appear to be playing important roles in their environments. However, low temperature data on the chemical pathways leading to their formation and destruction is still scarce, especially regarding product identity and branching ratios. To address this issue, we have engaged in the investigation of the reactivity of these molecular anions by employing dedicated instruments coupling subsonic and supersonic flows with mass spectrometry methods. In this fashion, we have investigated the reactivity of C3N¯ anions with cyanoacetylene (HC3N) as well as the reactivity of CN¯, C3N¯, and C5N¯ with formic acid (HCOOH) from 298 K down to temperatures as low as 36 K. We report in this work the rate coefficient, the nature of the products, and the branching ratios of these reactions.This work also addresses the prototype selected ion source in our laboratory, which was recently implemented in order to extend our investigation to other anions of astrophysical interest (e.g. CxH¯ and Cx¯ anions). A description of this instrument as well as some preliminary results are presented in this work. This thesis, «Reactivity of Molecular Anions at Low Temperature: Implications for the Chemistry of the Interstellar medium and Titan’s atmosphere», was carried out at the Institut de Physique de Rennes and the Ecole Nationale Supérieure de Chimie de Rennes.Keywords: astrochemistry, Titan’s atmosphere, molecular anions, gas phase kinetics, supersonic flow, mass spectrometry, selected ion source

A thorough description of the testing of a saddle-field ion source is presented in the diploma thesis. The most important experimental results, such as Faraday cup measurements of the ion beam current profile and of the ion energy spectra, are included. Based on these results it is shown that the optimized ion source works correctly and according to the expectations. At the end of the thesis, the development of the ion-optical and construction design of the focusing optics is described. The manufactured optics assembly attached to the ion source is also shown.

Mass spectrometers have proven to be vital to understanding the Solar System and the planets within it. Spacecraft containing mass spectrometers have been sent to numerous remote places and have determined important information about the atmospheric composition of Venus, Earth, Mars, Jupiter, and Saturn, along with other celestial bodies. Such results have shown a variety of small neutral molecules, such as CH4 NH3, H2O, CO2, and CO, neutral radicals such as atomic O, H, and N, and a host of small ions, such as H+, N+, and NH4+. Closed ion source inlets, which allow for the detection of these small neutral molecules, contain a spherical antechamber that allows the neutrals to thermalize with the walls of the chamber through many successive collisions before they are introduced into the ionization region of the spacecraft mass spectrometer. These collisions, however, energetically excite neutral molecules and lead to many chemical changes, such as racemization, ionization, or even dissociation. When these changes occur, smaller neutrals can be produced, even if they were not in the original sample from the atmosphere or surface. As a result, the determination of the true composition of an atmosphere or a surface is cast into doubt. Herein is given a brief description of mass spectrometry in space research and how the closed ion source has greatly assisted this process. Dissociation and other chemical changes caused by the high velocity impacts that occur in closed source antechambers is also addressed. A theoretical approach to understanding such dissociative processes that occur after high energy collisions in closed source antechambers is described and undertaken. Chapter 2 describes a proof-of-concept study using hexane as a representative molecule and determines the velocity at which widespread dissociation of hexane molecules is likely to occur in closed source antechambers. This same theoretical process is then utilized in Chapter 3 with many more members of the n-alkane family to probe what effect molecular weight has on the amount of dissociation. Alkanes of both higher and lower molecular weight than hexane (C6H14) are used to show the effect as a function of molecular weight. In all cases, it was found that the velocity at which half of the incoming neutral n-alkane molecules dissociate is roughly the same for all molecular weights studied. This result is then applied to current and future space research through a proposed hardware solution, which will reduce the amount of dissociation and a discussion of how this effect may be seen in the results obtained from future mission instruments. Lastly, future work with different molecular weights and with successive collisions (the second, third, fourth, etc.) is described. This future work will further expand the present study to show how different functional groups, which may be partly responsible for higher-than-expected levels of NH3 and CO2, are affected after a high velocity, high energy impact.

Hochgeladene Ionen stellen einen extremen Zustand der Materie dar, wie sie vornehmlich in kosmischen Plasmen zu finden ist. Die labormäßige Erzeugung und (spektroskopische) Untersuchung hochgeladener Ionen liefert wichtige Daten und Erkenntnisse für die Astrophysik und Fusionsforschung. Aufgrund ihrer zum Teil exotischen Eigenschaften besitzen hochgeladene Ionen ein großes Potential für eine Vielzahl neuer Anwendungen. Die bisher weltweit einzige Elektronenstrahl-Ionenfalle, die hochgeladene Ionen bis hin zu vollständig ionisierten Ionen unter Raumtemperaturbedingungen erzeugen und bereitstellen kann, die Dresden EBIT, ist Gegenstand der vorgelegten Arbeit. Die Dresden EBIT zeichnet sich neben ihrer Kompaktheit und einer einfachen Bedienung durch ihre Langzeitstabilität aus. Sowohl über Röntgenspektren als auch über die Extraktion der Ionen aus der EBIT konnte für eine Reihe von Elementen der Nachweis der Erzeugung von vollständig ionisierten Ionen bis Z=28 erbracht werden. Für schwere Elemente können Ionenladungszustände bis hin zu neonähnlichen Ionen erzeugt werden. Entscheidenden Einfluss auf den erzielten mittleren Ladungszustand hat die Ioneneinschlusszeit. Die zeitliche Entwicklung der Ladungszustandsverteilung, wie sie im Zusammenspiel der verschiedenen atomaren Prozesse simuliert werden kann, ist sowohl an einer Reihe von röntgenspektroskopischen Messungen als auch anhand von Extraktionsspektren untersucht worden. Neben der Beladung der EBIT mit gasförmigen Elementen ist insbesondere die Beladung mit Metallen, d. h. mit einem möglichst breiten Spektrum an Elementen gefordert. Die Beladung mit leichtflüchtigen metallorganischen Verbindungen, die über das Gaseinlassventil eingebracht werden können, hat sich als erfolgreiche und preiswerte Alternative zu einer MEVVA-Quelle erwiesen. Die Beladung mit Metallionen ist am Beispiel verschiedener Untersuchungen gezeigt. Der monoenergetische Elektronenstrahl gestattet neben der Untersuchung von Anregungs- und Ionisationsprozessen insbesondere die der wichtigen Rekombinationsprozesse des Strahlenden Einfangs und der Dielektronischen Rekombination. Der Einsatz eines Kristalldiffraktionsspektrometers erlaubt trotz einer aufwendigen Kalibrierung und sehr langen Messzeiten die Auflösung einzelner Übergänge in hochgeladenen Ionen. Hauptanwendungsfeld der Dresden EBIT wird der Einsatz als Ionenquelle sein. Aus den Untersuchungen des extrahierten Gesamtionenstroms können die Bedingungen für einen möglichst großen Ionenstrom und einen optimalen Ionenstrahltransport abgeleitet werden. Eine optimale Ausnutzung der Eigenschaften hochgeladener Ionen erfordert die Separation der einzelnen Ladungszustände. Der Nachweis der sehr kleinen Ionenströme erfolgt über die kapazitive Messung in einem Faradaycup. Die Messung der Ladungszustandsverteilung in Abhängigkeit von den Parametern der EBIT gibt zusätzliche Aufschlüsse über die Eigenschaften der Ionenfalle.