The space environment possesses numerous unique and unusual attributes, creating challenges that must be considered in order to accomplish a successful space mission. Two of the detrimental aspects of the space environment include Atomic Oxygen, AO, and Ultraviolet, UV, radiation. UV radiation becomes more severe in space as there is no atmosphere to attenuate incoming photons, thereby exposing spacecraft to radiation that never reaches the surface of the Earth. Overall, space vehicles are exposed to a total of 107.4 Watts/m2 of light shorter than 400 nm. AO is created by the photo disassociation of molecular oxygen by UV radiation with wavelengths less than ~242.1 nm. AO is a major portion of the neutral atmosphere, and is the dominant species for altitudes between 180 and 675 km. Each of these environments can cause significant damage to spacecraft materials as they have sufficient energy to break molecular bonds: a generalization of AO energy is 4.5 +/- 1 eV while Vacuum Ultraviolet, VUV, radiation can break bonds as strong as 12.4 eV. Synergistic affects are observed when these two environments interact with materials simultaneously, resulting in an accelerated erosion rate. An apparatus has been developed in California Polytechnic State University’s, Cal Poly’s, space environments laboratory that can simulate the AO and VUV environments individually and simultaneously. This apparatus utilizes a radio frequency, RF, generator to produce a capacitively coupled plasma to create AO in conjunction with a deuterium lamp capable of emitting UV radiation as short as 115 nm. The system has been shown to produce an AO flux of 1.70 +/- 0.07•1016 atoms/cm2 while providing an equivalent sun power 4.5 times greater the solar output in the 120-200 nm region of UV light; all of this has been performed at a base pressure near 175 mTorr. Long duration tests of 24 hours, which would be analogous to durations used in a material interaction study, have shown an effective fluence of 1.47 +/- 0.06•1021 atoms/cm2, which would equate to an orbital exposure on the order of weeks to months. For the same duration a sample can be exposed to 108 equivalent sun hours of 120-200 nm radiation. Results from the simultaneous exposure also manifested an accelerated erosion rate, the expected synergetic reactions between the two environments.

Solar sails have the potential to benefit many future space exploration missions, but they lack the heritage required for present-day use. To grow confidence in solar sail technology, they could be deployed on LEO satellites higher than 600 km to help de-orbit the satellite within 25 years upon mission termination. To determine how atomic oxygen would affect the solar sail, material from Lightsail-2 was tested in a thermal-energy, isotropic, atomic oxygen vacuum chamber based in the space environments laboratory in California Polytechnic State University. The sail material, aluminized Mylar, was tested for its survivability on both the coated and uncoated side, as well as tested for the optical degradation of the coated side. The uncoated side was found to be completely eroded after a fluence of 2.27 x1020 atoms/cm2, or ~40 days in International Space Station orbit. The coated side experienced no mass loss, but signs of significant undercutting were found with a fluence of 1.19 x1021 atoms/cm2, or ~200 days at station orbit. The stitches present on the coated side, meant to prevent tear propagation, eroded before the sample experienced a fluence of 4.13 x1020 atoms/cm2, or ~70 days at station orbit. The average total reflectivity of the material dropped by ~5% after atomic oxygen exposure, however no correlation with fluence was found. Average specular reflectivity remained unchanged after atomic oxygen exposure. The reflectivity results were impacted by wrinkling in the material, which was found to have a much larger impact than atomic oxygen exposure. These results were paired with an optimal de-orbit trajectory algorithm, developed in this thesis, to determine how atomic oxygen would affect a solar sail deployed to de-orbit an 800 km LEO satellite with a ballistic coefficient of 0.1. Using a simplified 2D orbit case, it was found that the satellite would de-orbit within 12-18 years, depending primarily on the solar activity level. The measured worst-case for optical degradation increased de-orbit time by ~6 months. Additionally, assuming that the sail material was perfectly reflecting decreased de-orbit time by 2-4 years. The amount of fluence required to erode the uncoated Mylar, and the amount required to erode the stitches, were both reached long before the satellite re-entered. It is therefore recommended that the solar sail minimize uncoated side exposure to atomic oxygen, and a more atomic oxygen-resistant stitch material be found. The fluence required to produce significant material undercutting was reached only once the satellite’s orbit had degraded to below 400 km. But the undercutting was observed to structurally compromise the material; thus, future LEO solar sail mission designers must take care when balancing added performance with higher failure risk when considering the tension in the deployed sail.

This report presents an investigation and development of the methods for orbital object identification. Two goals were accomplished in this master’s thesis; the development of a method of inverting material proportions from an object’s combined spectrum, and the investigation of methods and initialization of measurement of space environment effects on spectral features of common spacecraft materials. A constrained least squares approach was chosen for inverting spectral proportions from the combined spectra. The final results fall within 1 - 15% of the original spectrum, depending on the quality and noise levels of the original spectrum. Additionally, the effects of outgassing and atomic oxygen erosion were measured using the vacuum chamber facilities at California Polytechnic State University and are to be used as a basis for future identification of orbital debris. To have a fully functional model for accurately identifying space objects, both parts are needed: a set of space environment effect measurements as a basis for the identification model (for use on objects exposed to the space environment), and the identification model to mathematically determine the best fit set of materials.

This dissertation comprises multiple studies surrounding the middle atmosphere's chemistry, composition, and dynamics. The middle atmosphere refers to the region from ~ 10 km to ~ 100 km and consists of the Stratosphere, Mesosphere, and Lower Thermosphere. The Stratosphere, Mesosphere, and Thermosphere are bounded by pauses where the strongest changes in chemical composition, movement, density, and thermal behavior take place. While several studies in the past have investigated the chemical composition of the middle atmosphere and quantified the distribution of various species from the stratosphere to the lower thermosphere, seasonal variations and redistribution of species resulting from transport events make it important to continuously monitor the middle atmosphere. Dynamic events such as Sudden Stratospheric Warmings (SSW) impact the temperature gradient and the zonal mean wind pattern in the stratopause. Descent events triggered by SSWs result in enhanced transport of species from the lower thermosphere to the stratosphere. Temperature increments during SSWs have an important impact on Polar Stratospheric Clouds (PSCs), resulting in Antarctic ozone enhancement and a smaller ozone hole. The middle atmosphere is, thus, home to a diverse range of dynamics and chemistry, making it a critical subject that warrants attention from the science community. The continuous monitoring of the middle atmosphere is important to this end. Several satellite missions in the past have been dedicated to monitoring the middle atmosphere and collecting data for decades. However, continual revisions and revaluations of measurement approaches and the introduction of novel space instruments are necessary to compensate for the limitations associated with existing missions, expand the extant specimen database, and improve phenomenon-centric observations. The Solar Occultation for Ice Experiment (SOFIE) is one of the two instruments on the Aeronomy of Ice in the Mesosphere (AIM) spacecraft. The studies presented in this dissertation primarily focus on the use of SOFIE observations combined with results from other science missions, an atmospheric model, and other datasets. Chapter I is an overview of the research goals and the motivations that propelled this research. In Chapter II, a validation study of the Version 1.3 SOFIE ozone data against the Atmospheric Chemistry Experiment (ACE) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) ozone data is presented. The SOFIE-ACE and SOFIE-MIPAS data pairs demonstrate similar variability in the ozone vertical profile. SOFIE vertical ozone profiles agree best with ACE from 30 - 70 km and MIPAS from 30-64 km. The mean difference values averaged over all seasons and both hemispheres are typically < 24% with ACE and < 20 % with MIPAS. Atomic oxygen is an important species in the mesopause region (~ 80 – 100 km) that impacts the region's ozone photochemistry and radiative balance. In Chapter III, SOFIE ozone measurements used to derive daytime atomic oxygen are compared to coincident retrievals from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument and the Naval Research Laboratory Mass Spectrometer Incoherent Scatter radar (NRLMSIS 2.0) model. The datasets agree qualitatively. Results indicate a strong seasonal variation of atomic oxygen with summer and wintertime maxima at ~ 84 km and 94 km, respectively. The middle atmospheric composition is redistributed by the transport of species during SSWs. In Chapter IV, the 2019 SSW in the northern hemisphere that triggered a large transport event from the lower thermosphere to the stratosphere is evaluated using SOFIE, ACE, and the Modern-Era Retrospective analysis for Research and Applications (MERRA-2) observations. The event was similar to the major SSW-triggered descent events in the northern hemisphere since 2004 and led to the enhancement of nitric oxide produced by Energetic Particle Precipitation, attributed to unusual meteorology. The transport peak descended by ~ 5-6 km every 10 days. An SSW event occurred in the southern hemisphere in 2019 and led to enhanced ozone in the stratosphere. In Chapter V, satellite instruments, ground station data, and measurements from NASA Ozone Watch are used to conclude that large temperature increments evaporated PSCs, resulting in the lower conversion of halogen reservoir species into ozone-destroying forms. Thus, a large ozone enhancement was recorded in 2019. Chapter VI concludes all findings and Chapter VII summarizes future work. / Doctor of Philosophy / The middle atmosphere is the region between ~ 10 and 100 km in the atmosphere and is comprised of the Stratosphere, Mesosphere, and Lower Thermosphere. The middle atmosphere is a dynamic region, and the chemistry of this region is subject to variations occurring naturally or those triggered by anomalous events such as Sudden Stratospheric Warmings (SSW). Several species in the middle atmosphere need to be measured continuously or reevaluated for improved understanding. Dynamical events in the middle atmosphere are responsible for transporting and redistributing species in the middle atmosphere. Thus, the continuous monitoring of the middle atmosphere is necessary. Novel approaches with improved techniques and approaches are thus important to explore the middle atmosphere and quantify the chemistry of the region. The Solar Occultation for Ice Experiment (SOFIE) instrument is an instrument onboard the Aeronomy of Ice in the Mesosphere (AIM) spacecraft. SOFIE typically measures at high latitudes and looks at a wide range of wavelengths. This dissertation uses SOFIE and other datasets to evaluate the varying chemistry and dynamics of the middle atmosphere. The dissertation addresses four research problems and assimilates them to evaluate the middle atmosphere. Ozone is an important species in the middle atmosphere, which is present in the highest quantity in the stratosphere, followed by the lower thermosphere (~ 85 – 100 km). Ozone is important as it absorbs ultraviolet radiations and impacts the stratospheric radiative balance. Missions in the past have monitored ozone in the middle atmosphere. Novel approaches and improved observation techniques to compensate for the limitations of past missions and the continuous measurement of ozone are necessary. Thus, ozone retrievals from SOFIE are validated against independent and established datasets to demonstrate the robustness and usability of the SOFIE ozone data product within the atmospheric science community. Atomic oxygen is an important species in the mesopause region (~ 80 – 100 km) because of its role in ozone photochemistry and impact on the radiative balance of the region. It is technologically challenging to make direct measurements of atomic oxygen; thus, most conventionally, derived measurements and model results are used. To this date, atomic oxygen has been understood in a limited capacity with several inaccuracies. To improve the understanding of atomic oxygen and fill the current knowledge gaps, atomic oxygen is derived from SOFIE ozone measurements during the daytime using the Chapman equations for ozone photochemistry. Further, the derived atomic oxygen is compared to other established datasets from satellite instrument-derived measurements and model predictions. The seasonal variability of atomic oxygen is evaluated with a focus on the difference in its behavior during summer and winter. Lastly, inter-hemispheric differences in atomic oxygen distribution are evaluated. Apart from the natural atmospheric variation in species, SSW-triggered transport events redistribute species in the atmosphere. The 2019 SSW event in the northern hemisphere was similar to those in 2004, 2006, 2009, and 2013. Large quantities of nitric oxide were transported from the lower thermosphere to the stratosphere. Air poor in water vapor and methane was also transported. Atomic oxygen was transported from the lower thermosphere to several kilometers below in amounts higher than usual. The increased nitric oxide concentration in the stratosphere due to the transport catalytically destroyed the ozone in the region. The vertical transport rates were calculated to understand the speed of the descent. The low geomagnetic index in 2019, like in all years besides 2004, indicates that these events are attributed to unusual meteorology. An SSW event took place in the southern hemisphere in 2019 during the Antarctic winter. This led to a large increase in temperature, which evaporated the Polar Stratospheric Clouds (PSCs). PSCs provide their surface for converting halogen reservoir species into ozone-destroying reactive forms. The absence of PSCs during and immediately after the SSW event led to a lower conversion of halogen reservoir species into reactive forms. Satellite instrument measurements agree with theoretical expectations. The 2002 SSW in the SH led to similar outcomes and are compared to the 2019 event. Large enhancements in ozone in 2019 led to the smallest ozone hole since ~ 1982.

Additive manufacturing (AM) is a rapidly developing manufacturing method utilized in fields such as the aerospace industry. In-space AM is a technology of interest for the future of spaceflight, including on-orbit manufacturing. However, AM materials are subject to defects that may impact their performance in space-based applications. How these defects change the material’s reaction to the space environment, specifically atomic oxygen (AO), has only recently been explored. AO is a highly corrosive, dominant constituent in low Earth orbit that causes continuous erosion of spacecraft surfaces. The effect of AO on various AM materials is investigated in this thesis. Stainless steel, aluminum, ULTEM™, and titanium samples made using differing AM techniques were exposed to 24 hours of AO in order to calculate material susceptibility in the form of erosion yield. Additionally, reflectance spectra were collected to detect changes in material at the surface. Over 24 hours, samples were exposed to an average fluence of 9.10 × 1020 atoms cm−2, equating to about 200 times the naturally occurring AO flux at International Space Station altitudes. The statistical significance of effects from AO exposure were determined. Comparisons were drawn between the AM materials tested and conventionally manufactured materials. It was found that mass loss due to AO erosion was significant for ULTEM™, powder bed fusion titanium, and directed energy deposition titanium. The ULTEM™ tested in this thesis had significantly higher erosion yield when compared to ULTEM™ tested by NASA, while all other material comparisons had insufficient evidence to draw similar conclusions. Reflectance spectra did not reveal unexpected differences before and after exposure.

This diploma thesis is focused on the charge exchange processes between projectile and target studied by the Low Energy Ion Scattering (LEIS) technique. Basic premise to investigate charge exchange processes is correct cleaning processes and proper settings of experimental instrument Qtac 100 placed in the Central European Institute of Technology (CEITEC) in Brno. Ion fraction expresses neutralization rate of the projectile. The parametr is investigated for clean and oxidized polycrystalline copper. Oxygen presence performs a significant part of reionization of backscattered neutralized projectiles.

Depuis l'invention du transistor MOS à effet de champ dans les années 60, l'exploitation de cette brique élémentaire a permis une évolution exponentielle du domaine de la microélectronique, avec une course effrénée vers la miniaturisation des dispositifs électroniques CMOS. Dans ce contexte, l'introduction des oxydes "high-κ" (notamment HfO2) a permis de franchir la barrière sub-nanométrique de l'EOT (Equivalent Oxide Thickness) pour l’oxyde de grille. Les travaux actuels concernent notamment la recherche de matériaux "high-κ" et de procédés qui permettraient d'avoir une interface abrupte, thermodynamiquement stable avec le silicium, pouvant conduire à des EOTs de l'ordre de 5Å. L’objectif de cette thèse, était d’explorer le potentiel de l’oxyde LaAlO3 amorphe déposé sur silicium par des techniques d’Épitaxie par Jets Moléculaires, en combinant des études sur les propriétés physico-chimiques et électriques de ce système. Le travail de thèse a d’abord consisté à définir des procédures d'élaboration sur Si de couches très minces (≈4nm), robustes et reproductibles, afin de fiabiliser les mesures électriques, puis à optimiser la qualité électrique des hétérostructures en ajustant les paramètres de dépôt à partir de corrélations entre résultats électriques et propriétés physico-chimiques (densité, stœchiométrie, environnement chimique…) et enfin à valider un procédé d'intégration du matériau dans la réalisation de MOSFET. La stabilité et la reproductibilité des mesures ont été atteintes grâce à une préparation de surface du substrat adaptée et grâce à l'introduction d'oxygène atomique pendant le dépôt de LaAlO3, permettant ainsi une homogénéisation des couches et une réduction des courants de fuite. Après optimisation des paramètres de dépôt, les meilleures structures présentent des EOTs de 8-9Å, une constante diélectrique de 16 et des courants de fuite de l'ordre de 10-2A/cm². Les caractérisations physico-chimiques fines des couches par XPS ont révélé des inhomogénéités de composition qui peuvent expliquer que le κ mesuré soit inférieur aux valeurs de LaAlO3 cristallin (20-25). Bien que les interfaces LAO/Si soient abruptes après le dépôt et que LaAlO3 soit thermodynamiquement stable vis-à-vis du silicium, le système LAO amorphe /Si s’est révélé instable pour des recuits post-dépôt effectués à des températures supérieures à 700°C. Un procédé de fabrication de MOSFETs aux dimensions relâchées a été défini pour tester les filières high-κ. Les premières étapes du procédé ont été validées pour LaAlO3. / Since MOS Field Effect Transistor invention in the 60's, the exploitation of this elementary piece of technology allowed an exponential evolution in the microelectronic field, with a frantic race towards miniaturization of CMOS electronic devices. In this context, the introduction of "high-κ" oxides (notably HfO2) allowed to cross the sub-nanometer barrier of EOT (Equivalent Oxide Thickness) for the gate oxide. Current work are notably related to "high-κ" research materials and processes that would allow an abrupt and thermodynamically stable interface with respect to silicon, that may lead to EOTs of about 5Å. The purpose of this thesis was to explore the potential of amorphous oxide LaAlO3 deposited on silicon by techniques of molecular beam epitaxy, combining studies of the physicochemical and electrical properties of this system. The thesis work has first consisted in defining procedures for the preparation of very thin (≈ 4 nm), robust and reproducible layers on Si in order to allow reliable electrical measurements then to optimize the electrical quality of the hetero-structures by adjusting deposition parameters from correlations between electrical results and physicochemical properties (density, stoichiometry, chemical environment...) and finally to validate a method for integrating the material in the realization of MOSFET. The stability and reproducibility of the measurements were achieved thanks to an adapted surface preparation of the substrate and by the introduction of atomic oxygen during the LaAlO3 deposition, thus allowing homogenization of layers and reducing leakage currents. After optimizing the deposition parameters, the best structures exhibit EOTs of 8-9 A, a dielectric constant of 16 and leakage currents in the range of 10-2 A/cm². Accurate physico-chemical characterizations of thin layers by XPS revealed composition inhomogeneities that can explain why the measured κ is less than values of crystalline LaAlO3 (20-25). Although the LAO/Si interfaces are steep after deposition and LaAlO3 is thermodynamically stable with respect to the silicon, amorphous system LAO/Si has proven unstable during post-deposition annealing carried out at temperatures above 700 ° C. A process for producing MOSFETs with released dimensions was defined to test high-κ field. The first stages of the process have been validated for LaAlO3.