[en] The present discussion of resistive instabilities in cosmic plasmas emphasizes the qualitative changes that occur when theory proceeds from simple cases, where symmetry allows exclusion of one or two space coordinates, to the general 3D process. Due to a strong localization of resistive effects, the resistive instability occurs on a time-scale potentially much faster than magnetic diffusion for large values of the Lundquist number. It is shown that the general magnetic reconnection is adequate for describing 3D resistive instability processes, including cases where the magnetic field has no such singularities as magnetic nulls. 36 refs

[en] In order to measure the distance of a body, e.g. an airplane, from a water surface a neutron source for fast neutrons and a neutron detector for thermal neutrons are used. Both are within the airplane and shielded from one another and from the interior of the plane. The fast neutrons are directed to the water surface and the thermal albedo neutrons then emitted from the water are picked up by the neutron detector, e.g. a BF₃ counter. (DG)

[en] In taillike configurations magnetic reconnection necessarily leads to the formation of plasmoids. This paper analyses the dynamical evolution of the developing plasmoids and the influence of magnetic reconnection on the propertie of plasmoids. By two dimensional resistive MHD calculations it is shown that plasmoid properties depend very much on the reconnection process especially when the reconnection rate is large. Thus the early plasmoid formation is dominated by magnetic reconnection. At later times the main plasmoid acceleration is due to pressure forces while the tension of open interplanetary fieldlines is negligible. The comparison of different resistivity and equilibrium modells reveals a definite influence of the microscopic dissipation and the initial state on magnetic reconnection and the resulting evolution of plasmoids. (author). 8 refs.; 6 figs

No abstract available

No abstract available

[en] Due to its intrinsic high brightness, high stability, and proportionality to the stored electron beam current, synchrotrons IR spectroscopy has revealed itself as an unique tool to experimentally test a physical phenomenon occurring at metallic interfaces, the theory for which was motivated by previous observations. Any adsorbate induces inelastic scattering of the conduction electrons, which causes a broadband IR reflectance change, and was predicted to induce a concomitant DC resistivity change. By choosing a well ordered single crystal thin film of Cu(111), we have checked that the DC resistivity change, and the asymptotic limit of the IR reflectance change are linearly dependent, but independent of the nature of the adsorbate. Coadsorption experiments which have been used to modify the induced density of states at the Fermi level, have further demonstrated that the friction coefficient, which is responsible for the elastic scattering phenomenon, is chemically specific. This article describes the use of synchrotron radiation as an absolute source and its application to the study of dynamics of adsorbates on surfaces

No abstract available

No abstract available

[en] The structural properties of two mechanically activated commercial LaNi₅ type battery materials and their deuterides have been investigated by means of in situ neutron powder diffraction analysis. A discussion of the hysteresis between the absorption and desorption isotherms is given. Using standard Rietveld refinement procedures, information on the variation of the deuterium site occupancy, the lattice symmetry and the cell volume are also presented. In particular, we report on the variation of line-broadening with concentration as well as on the complex time-dependent changes in the lattice parameters and the line-broadening following a step change in the deuterium pressure. We then show that these relatively novel data provide valuable information on the rather different phase transition processes observed for the two materials and offer an explanation for the superior kinetics of the AB_4.8 alloy

[en] The use of electrochemically structured Al surfaces as sensor arrays for combinatorial chemistry and its detection via microscopic laser techniques from very small volumes has been explored. The methodology is based on three different techniques which will be discussed separately: firstly, attenuated total reflection (ATR) is used in connection with surface-plasmon-polariton (SPP) excitation. A thin Al layer, evaporated on sapphire or quartz and covered with a naturally grown oxide layer, provides an optimum enhancement and confinement of the electrical field close to the surface. This is revealed by calculations and experimental data. Secondly, a Raman microscope is applied, enabling chemical spot analysis in the visible and UV range with a lateral resolution close to the diffraction limit. Finally, its application to investigate electrochemically structured Al films is discussed