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See detailInżyneria powierzchni betonu. Część 2. Wpływ obrobki na powstawanie rys
Courard, Luc ULg; Garbacz, Andrzej; Nieweglowska, Anna et al

in Materialy Budowlane (2006), 12

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See detailInżynieria powierzchni betonu. Część 3. Termodynamiczne uwarunkowania adhezji
Courard, Luc ULg; Garbacz, Andrzej; Piotrowski, Tomasz

in Materialy Budowlane (2007), 2

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See detailThe Io Footprint Morphology
Jacobsen, Sven; Saur, Joachim; Neubauer, F. M. et al

Conference (2008, September 23)

The innermost Galilean moon Io is embedded in a dense plasma torus. It disturbs the flow of the corotating torus plasma and generates MHD waves. Especially the Alfv ́ n e mode, which carries electric ... [more ▼]

The innermost Galilean moon Io is embedded in a dense plasma torus. It disturbs the flow of the corotating torus plasma and generates MHD waves. Especially the Alfv ́ n e mode, which carries electric currents along the magnetic field, is responsible for the famous Io footprint in the Jo- vian aurora. The Alfv ́ n waves are partly reflected at plasma e density gradients e.g. at the torus edges and form a compli- cated wave pattern. The footprint morphology in the Jovian aurora displays this pattern. Besides the main spot feature, a trailing wake extending over up to 100 degrees and occa- sionally occurring multiple spots indicating reflections have been identified. The intensity, the occurrence of multiple spots and the inter-spot distances have been found to vary strongly [1]. Io is moving up and down in the plasma torus confined to the centrifugal equator. It interacts with a dense plasma when located in the torus center and considerably thinner plasma at the torus flanks. The incoming plasma density controls the interaction strength and wave amplitude. This primar- ily leads to a relationship between the footprint brightness and Io’s centrifugal latitude [1]. However, it has also been shown that the reflection angle is strongly depending on the wave amplitude due to nonlinear effects [2]. This has an impact on the inter-spot distances. On the other hand this parameter is also directly affected when Io changes its posi- tion in the plasma torus. To deconvolve this system we present the results of our 3D MHD simulations showing the influence of Io’s centrifugal latitude and nonlinearities on the footprint morphology par- ticularly on the number of spots and inter-spot distances. We observe interference phenomena leading to locally en- hanced or reduced footprint brightness. We also discuss the recently observed leading spot feature [3]. [less ▲]

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See detailIo footprint: Position, Multiplicity, Variability
Bonfond, Bertrand ULg; Gérard, Jean-Claude ULg; Grodent, Denis ULg et al

Conference (2006, July)

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See detailIo plasma torus science through UV remote sensing
Grodent, Denis ULg

Scientific conference (2013, November)

In this presentation, I am providing a short review of the scientific information on the Io plasma torus that may be inferred from UV remote sensing. This includes past observations with the Hubble Space ... [more ▼]

In this presentation, I am providing a short review of the scientific information on the Io plasma torus that may be inferred from UV remote sensing. This includes past observations with the Hubble Space Telescope and the Cassini-UVIS spectrograph during the 2000-Jupiter flyby and future observations with the EXCEED (Sprint-A) telescope. [less ▲]

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See detailIo robot tu bambino
Denis, Brigitte ULg

in Compuscuola (1989), 38(juin), 43-48

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See detailThe Io UV footprint: Location, inter-spot distances and tail vertical extent
Bonfond, Bertrand ULg; Grodent, Denis ULg; Gérard, Jean-Claude ULg et al

in Journal of Geophysical Research. Space Physics (2009), 114

The Io footprint (IFP) consists of one or several spots observed in both jovian hemispheres and is related to the electromagnetic interaction between Io and the magnetosphere. These spots are followed by ... [more ▼]

The Io footprint (IFP) consists of one or several spots observed in both jovian hemispheres and is related to the electromagnetic interaction between Io and the magnetosphere. These spots are followed by an auroral curtain, called the tail, extending more than 90° longitude in the direction of planetary rotation. We use recent Hubble Space Telescope images of Jupiter to analyze the location of the footprint spots and tail as a function of Io's location in the jovian magnetic field. We present here a new IFP reference contour---the locus of all possible IFP positions---with an unprecedented accuracy, especially in previously poorly covered sectors. We also demonstrate that the lead angle - the longitudinal shift between Io and the actual IFP position - is not a reliable quantity for validation of the interaction models. Instead, the evolution of the inter-spot distances appears to be a better diagnosis of the Io-Jupiter interaction. Moreover, we present observations of the tail vertical profiles as seen above the limb. The emission peak altitude is ~900 km and remains relatively constant with the distance from the main spot. The altitudinal extent of the vertical emission profiles is not compatible with precipitation of a mono-energetic electron population. The best fit is obtained for a kappa distribution with a characteristic energy of ~70 eV and a spectral index of 2.3. The broadness of the inferred electron energy spectrum gives insight into the physics of the electron acceleration mechanism at play above the IFP tail. [less ▲]

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See detailIo's interaction with Jupiter's magnetosphere
Dols, Vincent ULg

Doctoral thesis (2011)

Io, the innermost Galilean moon of Jupiter, is the most volcanic body of the solar system. This volcanism is responsible for a tenuous atmosphere composed mainly of S, O and SO2. This atmosphere is ... [more ▼]

Io, the innermost Galilean moon of Jupiter, is the most volcanic body of the solar system. This volcanism is responsible for a tenuous atmosphere composed mainly of S, O and SO2. This atmosphere is constantly bombarded by the plasma that co-rotates with the magnetic field of Jupiter, producing new ions and perturbing locally the magnetic field. This local perturbation is responsible for auroral emissions in the atmosphere of Jupiter, at the foot of Io’s flux tube. The spacecraft Galileo made five flybys of Io between 1995 and 2001 at very low altitude (~100’s km) and made plasma and magnetic field measurements that reveal the complexity of Io’s interaction with Jupiter. Past studies have tackled the modeling of this interaction using different complementary approaches, each shedding a new light on the issue but each involving some simplifications. The MHD models (Linker et al., 1998) are based on an a priori parameterization of the ionization in the atmosphere, generally assuming spherical symmetry and a single atmospheric and plasma species (representative of O and S). They ignore the important effect of the cooling of electrons as well as the multi-species composition of both the plasma and the atmosphere. The two-fluid approach (Saur et al., 1999) computes precisely the ionization and collisions in the atmosphere of Io but make the assumption of a constant magnetic field, limiting the self-consistency of the model and potentially introducing large quantitative errors. We combine a multi-species chemistry model of the interaction that includes atomic and molecular species with a self-consistent Hall-MHD calculation of the flow and magnetic perturbation to model as self-consistently as possible the plasma variables along the different flybys of Io by the Galileo probe. [less ▲]

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See detailIo's volcanism controls Jupiter's radio emissions
Yoneda, Mizuki; Tsuchiya, F.; Misawa, H. et al

in Geophysical Research Letters (2013)

Jupiter's sodium nebula showed an enhancement in late May through beginning of June, 2007. This means Io's volcanic activity and the magnetosphere's plasma content increased during this period. On the ... [more ▼]

Jupiter's sodium nebula showed an enhancement in late May through beginning of June, 2007. This means Io's volcanic activity and the magnetosphere's plasma content increased during this period. On the other hand, Jupiter's radio emission called HOM became quiet after the sodium nebula enhancement. The HOM emission is considered to be related to activity of aurorae on Jupiter. These observation results therefore suggest that the increase in plasma supply from Io into Jupiter's magnetosphere weakens its field aligned current, which generates the radio emissions and aurorae on Jupiter. By comparing our observation results to recent model and observation results we add supporting evidence to the possibility that Io's volcanism controls Jupiter's magnetospheric activity. [less ▲]

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Peer Reviewed
See detailIodide organification disorder in autonomous thyroid nodule.
Tang, B. N. T.; Corvilain, B.; Seret, Alain ULg et al

Poster (2005, November 15)

Detailed reference viewed: 16 (0 ULg)
Peer Reviewed
See detailIodide organification disorder in autonomous thyroid nodule.
Tang, B.; Corvilain, B.; Seret, Alain ULg et al

in European Journal of Nuclear Medicine and Molecular Imaging (2006), 33(S2), 351

Detailed reference viewed: 30 (1 ULg)
See detailIon abundance rations of the Jovian magnetosphere
Radioti, Aikaterini ULg; Krupp, N.; Woch, J. et al

Conference (2004)

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See detailIon abundance ratios in the Jovian magnetosphere
Radioti, Aikaterini ULg; Krupp, N.; Woch, J. et al

in Journal of Geophysical Research. Space Physics (2005), 110

Galileo, as the first orbiting spacecraft around Jupiter, provides the opportunity to study globally the composition of the energetic ion population in the equatorial plane of the Jovian magnetosphere ... [more ▼]

Galileo, as the first orbiting spacecraft around Jupiter, provides the opportunity to study globally the composition of the energetic ion population in the equatorial plane of the Jovian magnetosphere. This enables us to derive the relative importance of the various sources and sinks of plasma and energetic particles in the largest magnetosphere of our solar system. In this paper we use data from the Energetic Particles Detector (EPD) on board Galileo and derive relative ion abundance ratio maps of S/O, S/He, O/He, and p/He. We extend the previous work in terms of global coverage, species, and energy range. In addition we compare them with previous results and especially with those derived on board Voyager 2. We found that the S/O abundance ratio is relatively constant throughout the magnetosphere decreasing slightly with radial distance. Within the error bars the S/O ratios could be reproduced. Only a minor energy dependence is observed for this ratio pointing to a common source for both ions. The S/He-, O/He-, and p/He-ratios decrease with increasing radial distance, furthering the notion that sulfur, oxygen, and protons originate mainly from a source within the Jovian system, in contrast with helium, which originates from the solar wind. A spectral kink observed at energies of several 100 keV/ nuc for all species and most pronounced for helium explains the observed energy dependence of the ratios relative to helium. Differences in the abundance ratios up to more than one order of magnitude between sequential orbits are evidence of large temporal variations taking place in the Jovian magnetosphere. These variations and the strong energy dependence can explain the differences between the results derived from Galileo EPD measurements and those from Voyager data. [less ▲]

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See detailIon beam figuring for precision optics
Gailly, Patrick ULg

E-print/Working paper (2008)

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See detailION BEAM FIGURING OF CVD SILICON CARBIDE MIRRORS
Gailly, Patrick ULg

in Warmbein, B (Ed.) Proceedings of the 5th International Conference on Space Optics (ICSO 2004) (2004, March)

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in ... [more ▼]

Optical and structural elements made of silicon carbide are increasingly found in space instruments. Chemical vapor deposited silicon carbide (CVD-SiC) is used as a reflective coating on SiC optics in reason of its good behavior under polishing. The advantage of applying ion beam figuring (IBF) to CVD-SiC over other surface figure-improving techniques is discussed herein. The results of an IBF sequence performed at the Centre Spatial de Liège on a 100 mm CVD-SiC mirror are reported. The process allowed to reduce the mirror surface errors from 243 nm to 13 nm rms . Beside the surface figure, roughness is another critical feature to consider in order to preserve the optical quality of CVD-SiC . Thus, experiments focusing on the evolution of roughness were performed in various ion beam etching conditions. The roughness of samples etched at different depths down to 3 m was determined with an optical profilometer. These measurements emphasize the importance of selecting the right combination of gas and beam energy to keep roughness at a low level. Kaufman-type ion sources are generally used to perform IBF but the performance of an end-Hall ion source in figuring CVD-SiC mirrors was also evaluated in this study. In order to do so, ion beam etching profiles obtained with the end-Hall source on CVD-SiC were measured and used as a basis for IBF simulations. [less ▲]

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See detailIon beam figuring of precision aspheric optical surfaces
Gailly, Patrick ULg; Collette, Jean-Paul; Tock, Jean-Philippe et al

Conference (1999)

An ion beam figuring facility is fully operational at the Centre Spatial de Liège since 1997. Ion beam figuring principle is briefly reminded and the present capabilities of the technique are described ... [more ▼]

An ion beam figuring facility is fully operational at the Centre Spatial de Liège since 1997. Ion beam figuring principle is briefly reminded and the present capabilities of the technique are described. An extensive characterisation programme is running in order to determine the optimised parameters for numerous materials and operating conditions. In this frame, tests have been performed on various optics to demonstrate the capability of the technique to figure aspheric shapes on glass or metallic substrates. At first, an aspherisation on a spherical gold-coated aluminium mirror plated in between with Nickel is presented. After removal of the gold coating with the ion beam, micro-roughness and etching rate measurements have been performed on the substrate material. Finally, the mirror has been figured from the original sphere to a parabola. The surface characteristics evolution is described in terms of micro-roughness and surface error. Other examples of complex aspherical figuring (polynomials of high order, ...) are shown. In conclusion, the potential impact and the results of this technique on optics fabrication, especially for exotic shapes, are exposed. The integration of the ion beam figuring process in a classical optics manufacturing sequence will be discussed, identifying the potential time and money savings. [less ▲]

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