Browsing by Author "Neumann, H."

Now showing 1 - 9 of 9
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    Abschlußbericht des BMBF-Projektes "Life Science Katalyse & Engineering - Katalytische Verfahren für die optimierte Wirkstoffsuche", Teilprojekt "Katalyse für Wirkstoffderivatisierungen"
    (Hannover : Technische Informationsbibliothek (TIB), 2004) Beller, Matthias; Giertz, S.; Gördes, D.; Kumar, K.; Lo, W.F.; Michalik, D.; Neumann, H.; Tillack, A.; Zapf, A.
    [no abstract available]
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    Advanced Electric Propulsion Diagnostic Tools at IOM
    (Amsterdam [u.a.] : Elsevier, 2017) Bundesmann, C.; Eichhorn, C.; Scholze, F.; Spemann, D.; Neumann, H.; Scortecci, F.; Leiter, H.J.; Holste, K.; Klar, P.J.; Bulit, A.; Dannenmayer, K.; Amo, J. Gonzalez del
    Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1], which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1], [4]), in two different vacuum facilities.
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    Dicyclohexylbis(naphthalen-1-ylmethyl)phosphonium chloride chloroform disolvate
    (Chester : International Union of Crystallography, 2012) Gowrisankar, S.; Neumann, H.; Spannenberg, A.; Beller, M.
    In the title solvated phosphonium salt, C34H40P+·Cl -·2CHCl3, the two cyclohexyl and two 1-naphthylmethyl groups at the P atom are in a distorted tetrahedral arrangement [105.26 (6)-113.35 (6)°]. Both cyclohexyl rings adopt a chair conformation. The dihedral angle between the naphthyl ring systems is 74.08 (3)°.
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    Examples for application and diagnostics in plasma-powder interaction
    ([London] : IOP, 2003) Kersten, H.; Wiese, R.; Thieme, G.; Fröhlich, M.; Kopitov, A.; Bojic, D.; Scholze, F.; Neumann, H.; Quaas, M.; Wulff, H.; Hippler, R.
    Low-pressure plasmas offer a unique possibility of confinement, control and fine tailoring of particle properties. Hence, dusty plasmas have grown into a vast field and new applications of plasma-processed dust particles are emerging. There is demand for particles with special properties and for particle-seeded composite materials. For example, the stability of luminophore particles could be improved by coating with protective Al2O3 films which are deposited by a PECVD process using a metal-organic precursor gas. Alternatively, the interaction between plasma and injected micro-disperse powder particles can also be used as a diagnostic tool for the study of plasma surface processes. Two examples will be provided: the interaction of micro-sized (SiO2) grains confined in a radiofrequency plasma with an external ion beam as well as the effect of a dc-magnetron discharge on confined particles during deposition have been investigated.
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    Feasibility of electrostatic microparticle propulsion
    (College Park, MD : Institute of Physics Publishing, 2008) Trottenberg, T.; Kersten, H.; Neumann, H.
    This paper discusses the feasibility of electrostatic space propulsion which uses microparticles as propellant. It is shown that particle charging in a plasma is not sufficient for electrostatic acceleration. Moreover, it appears technically difficult to extract charged particles out of a plasma for subsequent acceleration without them being discharged. Two novel thruster concepts are proposed. In the first one, particles with low secondary electron emission are charged using energetic electrons in the order of magnitude of 100eV. The second concept charges the particles by contact with needle electrodes at high electrostatic potential (∼20kV). Both methods allow the maximum possible charges on microparticles. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
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    Modelling of a radio frequency plasma bridge neutralizer (RFPBN)
    (Amsterdam [u.a.] : Elsevier, 2017) Scholze, F.; Eichhorn, C.; Bundesmann, C.; Spemann, D.; Neumann, H.; Bulit, A.; Feili, D.; Gonzalez del Amo, J.
    A performance model of a radio frequency plasma bridge neutralizer was developed to calculate the electrical parameters and optimize the neutralizer design. Minimization of power losses and gas consumption, and a maximization of the neutralizer lifetime and the reliability of the system are requirements of all electric propulsion concepts and strongly determine their future application. The requirements of the neutralizer depend on mission profiles.
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    Optimierung von Gittersystemen für elektrostatische Triebwerke : Abschlussbericht
    (Leipzig : Leibniz-Institut für Oberflächenmodifizierung, 2002) Hartmann, E.; Neumann, H.; Tartz, M.; Deltschew, R.
    [no abstract available]
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    (η6-Benzene)(carbonato-κ2O,O') [dicyclohexyl(naphthalen-1-ylmethyl)phosphanejP] ruthenium(II) chloroform trisolvate
    (Chester : International Union of Crystallography, 2014) Gowrisankar, S.; Neumann, H.; Spannenberg, A.; Beller, M.
    The title compound, [Ru(CO3)(η6-C 6H6){(C6H11)2P(CH 2-C10H7)}]-3CHCl3, was synthesized by carbonation of [RuCl2-(η6-C6H 6){(C6H11)2P(CH2C 10H7)}] with NaHCO3in methanol at room temperature. The RuIIatom is surrounded by a benzene ligand, a chelating carbonate group and a phosphane ligand in a piano-stool configuration. The crystal packing is consolidated by C-H⋯O and C-H⋯Cl hydrogen-bonding interactions between adjacent metal complexes and between the complexes and the solvent molecules. The asymmetric unit contains one metal complex and three chloroform solvent molecules of which only one was modelled. The estimated diffraction contributions of the other two strongly disordered chloroform solvent molecules were substracted from the observed diffraction data using the SQUEEZE procedure in PLATON.
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    (η6-Benzene)dichlorido(chlorodicyclohexylphosphane-κp) ruthenium(II) chloroform monosolvate
    (Chester : International Union of Crystallography, 2014) Gowrisankar, S.; Neumann, H.; Spannenberg, A.; Beller, M.
    The title compound, [RuN4(-6-C6H6) (C12H22ClP)]-CHCl3, was prepared by reaction of [RuN 4(-6-C6H6)]2 with chlorodicyclohexyl phosphane in CHCl3 at 323 K under argon. The RuII atom is surrounded by one arene ligand, two Cl atoms and a phosphane ligand in a piano-stool geometry. The phosphane ligand is linked by the P atom, with an Ru-P bond length of 2.3247 (4) Å. Both cyclohexyl rings at the P atom adopt a chair conformation. In the crystal, the RuII complex molecule and the chloroform solvent molecule are linked by a bifurcated C-H⋯(Cl,Cl) hydrogen bond. Intramolecular C-H⋯Cl hydrogen bonds are also observed.