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A. Friedman - One of the best experts on this subject based on the ideXlab platform.

  • Physics of neutralizatIon of intense High-Energy Ion Beam pulses by electrons
    Physics of Plasmas, 2010
    Co-Authors: Igor D Kaganovich, E. P. Lee, Adam B. Sefkow, Edward A. Startsev, R.c. Davidson, Mikhail A. Dorf, A. Friedman
    Abstract:

    NeutralizatIon and focusing of intense charged particle Beam pulses by electrons form the basis for a wide range of applicatIons to high energy accelerators and colliders, heavy Ion fusIon, and astrophysics. For example, for ballistic propagatIon of intense Ion Beam pulses, background plasma can be used to effectively neutralize the Beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagatIon of the Beam. From the practical perspective of designing advanced plasma sources for Beam neutralizatIon, a robust theory should be able to predict the self-electric and self-magnetic fields during Beam propagatIon through the background plasma. The major scaling relatIons for the self-electric and self-magnetic fields of intense Ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during Beam entry into the plasma, the excitatIon of collective plasma waves, the effects of gas IonizatIon, fini...

J W Geus - One of the best experts on this subject based on the ideXlab platform.

  • interfacial reactIons of transitIon metal oxides on aluminium oxide studied by high energy Ion Beam analysis techniques
    Studies in Surface Science and Catalysis, 1994
    Co-Authors: P H Bolt, F H P M Habraken, J W Geus
    Abstract:

    The usefulness of high energy Ion Beam analysis techniques, such as Rutherford Backscattering Spectrometry (RBS), Elastic Recoil DetectIon (ERD), and High Energy Ion Channeling (HEIS-c), in investigatIons of deactivatIon processes in (model) catalysts is demonstrated. These techniques have been applied to study interfacial MeAl 2 O 4 formatIon and the influence of water vapour on MeO/Al 2 O 3 model catalysts (Me = Ni, Co, Cu, Fe), and to follow sintering of Ni on α-Al 2 O 3 . We observed a much higher reactIon rate of spinel formatIon with γ-Al 2 O 3 than with α-Al 2 O 3 substrates. This rate was larger for cobalt and copper oxides layers than for nickel or iron oxides. Furthermore, it appeared that (in increasing rate order) cobalt, nickel and copper oxides disappear into the vapour phase, presumably as hydroxides, at 1000 °C in the presence of 0.3 atm steam.

F H P M Habraken - One of the best experts on this subject based on the ideXlab platform.

  • on line characterisatIon of radiofrequency magnetron sputter depositIon of siox using elastic recoil detectIon
    Thin Solid Films, 2006
    Co-Authors: E D Van Hattum, W M Arnoldbik, Alberto Palmero, F H P M Habraken
    Abstract:

    A radiofrequency Ar/O2 magnetron discharge is used to deposit silicon suboxide (SiOx ,0 x2) films. In this paper we demonstrate how we can apply the High-Energy Ion Beam technique elastic recoil detectIon (ERD) on-line, i.e. in situ during depositIon, to continuously monitor the growing layer thickness and depth resolved compositIon. From the ERD data the depositIon rates of distinctly silicon and oxygen and the compositIon of the growing film are determined. Using this method several growth conditIons can be investigated and compared in a fast and reliable manner on a single substrate. In this work we report the variatIon of the growth rate and of the compositIon of the growing layer as a result of the variatIon of the rf power and show the consequence of keeping the O2 flow constant in comparison to keeping the O2 partial pressure constant. D 2005 Elsevier B.V. All rights reserved.

  • the oxidatIon state of fe 100 after initial oxidatIon in o2
    Surface Science, 1999
    Co-Authors: S J Roosendaal, B Van Asselen, J W Elsenaar, A M Vredenberg, F H P M Habraken
    Abstract:

    Abstract Using a combinatIon of quantitative X-ray photoelectron spectroscopy (XPS) with the high energy Ion Beam technique elastic recoil detectIon (ERD), we focus on the chemical state of thin (a few nanometers) oxide films on Fe(100). We determined quantitatively the amounts of Fe 2+ and Fe 3+ in the oxide layer formed at room temperature and compared these with the absolute coverages of oxygen determined with ERD. For thin oxide layers (≤4.0×10 15  O atoms/cm 2 corresponding to 3 ML), the oxide layer grown on Fe(100) consists of Fe 2+ mainly, indicating the growth of FeO. Some Fe 0 also seems to be present in the oxide layer. For larger coverages additIonal Fe atoms in the oxide are in the 3+ state, which is present mainly near the oxide/vacuum interface. Annealing of the double layer system formed or oxidizing at higher temperature leads to an increase of the relative amount of Fe 2+ .

  • determinatIon of photoelectron attenuatIon lengths in thin oxide films on iron surfaces using quantitative xps and elastic recoil detectIon
    Surface and Interface Analysis, 1998
    Co-Authors: S J Roosendaal, A M Vredenberg, I A M E Giebels, F H P M Habraken
    Abstract:

    Thin oxide films play an important role in the corrosIon of metals. Using XPS it is possible in principle to obtain informatIon on the chemical state of near-surface atoms, the stoichiometry of the surface layer and its thickness. A problem is the quantificatIon of XPS spectra, due to the large uncertainty in the value of both electron attenuatIon lengths as well as sensitivity factors. By applying the Tougaard background subtractIon method and comparing only peak intensities of the Fe 2p and O 1s peaks with those of Fe, FeO and Fe2O3 reference samples, we determined the stoichiometry of the oxide layer grown on Fe(100) and Fe(110) at 200°C and room temperature to be Fe0.90±0.05O. We combined XPS with the High-Energy Ion-Beam technique of elastic recoil detectIon (ERD). By comparing the absolute coverages of oxygen determined by ERD with the intensities of different XPS peaks, we were able to determine the attenuatIon lengths for kinetic energies of 776 eV (Fe 2p) and 957 eV (O 1s) to be 9.3×1015 and 9.9×1015 Fe0.9O molecules cm−2, respectively. © 1998 John Wiley & Sons, Ltd.

  • interfacial reactIons of transitIon metal oxides on aluminium oxide studied by high energy Ion Beam analysis techniques
    Studies in Surface Science and Catalysis, 1994
    Co-Authors: P H Bolt, F H P M Habraken, J W Geus
    Abstract:

    The usefulness of high energy Ion Beam analysis techniques, such as Rutherford Backscattering Spectrometry (RBS), Elastic Recoil DetectIon (ERD), and High Energy Ion Channeling (HEIS-c), in investigatIons of deactivatIon processes in (model) catalysts is demonstrated. These techniques have been applied to study interfacial MeAl 2 O 4 formatIon and the influence of water vapour on MeO/Al 2 O 3 model catalysts (Me = Ni, Co, Cu, Fe), and to follow sintering of Ni on α-Al 2 O 3 . We observed a much higher reactIon rate of spinel formatIon with γ-Al 2 O 3 than with α-Al 2 O 3 substrates. This rate was larger for cobalt and copper oxides layers than for nickel or iron oxides. Furthermore, it appeared that (in increasing rate order) cobalt, nickel and copper oxides disappear into the vapour phase, presumably as hydroxides, at 1000 °C in the presence of 0.3 atm steam.

I N Mihailescu - One of the best experts on this subject based on the ideXlab platform.

  • mechanical properties improvement of pulsed laser deposited hydroxyapatite thin films by high energy Ion Beam implantatIon
    Applied Surface Science, 2002
    Co-Authors: V Nelea, Herve Pelletier, D Muller, N Broll, P Mille, C Ristoscu, I N Mihailescu
    Abstract:

    Major problems in the hydroxyapatite (HA), Ca 5 (PO 4 ) 3 OH, thin films processing still keep the poor mechanical properties and the lack in density. We present a study on the feasibility of high energy Ion-Beam implantatIon technique to densify HA bioceramic films. Crystalline HA films were grown by pulsed laser depositIon (PLD) method using an excimer KrF + laser (λ = 248 nm, τ FWHM > 20 ns). The films were deposited on Ti-5Al-2.5Fe alloys substrates previously coated with a ceramic TiN buffer layer. After depositIon the films were implanted with Ar + Ions at high energy. Optical microscopy (OM), white light confocal microscopy (WLCM), grazing incidence X-ray diffractIon (GIXRD) and Berkovich nanoindentatIon in normal and scratch optIons have been applied for the characterizatIon of the obtained structures. We put into evidence an enhancement of the mechanical characteristics after implantatIon, while GIXRD measurements confirm that the crystalline structure of HA phase is preserved. The improvement in mechanical properties is an effect of a densificatIon after Ion treatment as a result of pores eliminatIon and grains regrowth.

J L Miquel - One of the best experts on this subject based on the ideXlab platform.

  • fast neutron emissIon from a high energy Ion Beam produced by a high intensity subpicosecond laser pulse
    Physical Review Letters, 1999
    Co-Authors: L Disdier, J P Garconnet, G Malka, J L Miquel
    Abstract:

    Neutron emissIon as high as ${10}^{7}$ is observed when a high intensity (a few ${10}^{19}\mathrm{W}/{\mathrm{cm}}^{2}$) subpicosecond laser pulse at 529 nm wavelength is focused on a deuterated polyethylene target. Neutron emissIon is also measured in different directIons. The emissIon of neutrons along the laser axis is higher than in the transverse directIon. Nonisotropic emissIon is consistent with neutrons generated by $\mathrm{D}(d,n){\ensuremath{-}}^{3}\mathrm{He}$ reactIon for 0.3--1 MeV deuterons accelerated in the directIon of the laser Beam. The energy transferred to the Ions is roughly estimated and compared with the energy carried out by the electrons.