Streuung elektromagnetischer Oberflächen- und Volumenwellen an rauhen Oberflächen. Teil II. Die Streulichtverteilung; Ein- und Auskopplung von Oberflächenwellen

Scattering of Electromagnetic Surface and Bulk Waves from Rough Surfaces. Part II. The Indicatrix of Scattering; the Coupling of Surface and Bulk Waves In this paper, we present the calculation of the spectral power density of light scattered from homogenously isotropic and rough surfaces which are influenced by bulk or surface waves. A classification of all possible scattering cases in dependence on the wave types which arise in the regions z > O and z < O is given. The dependence of scattered light on scattering angles for the different possibilities of polarisation variantes (∥ and ?) will be presented. The relationship between the correlation function of roughness and the efficiency of coupling between bulk and surface modes will be discussed and compared with the results of other authors.     

Streuung elektromagnetischer Wellen an rauhen Oberflächen mit anisotroper Autokorrelationsfunktion

Scattering of Electromagnetic Bulk Waves from Rough Surfaces with Anisotropic Autocorrelation Function Starting with the theory of light scattering given in [1]. a general theory of scattering of electromagnetic waves from a rough surface is deduced. In the general case of arbitrary anisotropic autocorrelation functions (acf) the spectral power densities for all different possibilities of polarisation variants of excitation and scattered light will be presented. In the special case of an elliptically anisotropic acf of surface roughness the measurement of the position of the acf-main axes will be described and the strategy of analyse of the measured indicatrix of scattered light for determining the acf will be given.     

Streuung elektromagnetischer Wellen an einer rauhen Oberfläche

Mar?elja's theory of a superconductor without long-range order is cast in a microscopic form. As a consequence, it is found that such a superconductor is gapless. Therefore, measurements of the tunneling density of states should provide a test of this theory.     

Streuung von Licht an rauhen Oberflächen bei der Anregung von Oberflächenplasmonen

The electromagnetic theory, which explains the scattering of light from a rough surface of a metal foil by means of normale surface currents, is extended to the case of arbitrary directions of this currents. This allows to calculate the scattered intensity ofp ands polarised light in all directions. It is shown that the excitation of surface plasmons (“radiative” and “non radiative”) can produce a characteristic maximum in the scattered light. Detailed calculations for silver foils deposited on a quartz hemisphere are presented and compared with experiments. Furthermore the theory is applied to calculate the decrease in the reflection at frequences near the surface plasma frequenceΩ _s .     

Zur O2-Dissoziation in der Gleichstromglimmentladung. Teil I Bestimmung des Dissoziationsgrades mittels der O3-Bildung an gekühlten Oberflächen

The synthesis of ozone on the surface S cooled with liquid nitrogen O + O₂·S→O₃·S[1] was used to measure the concentration of atoms in a flow tube downstream of a d.c. discharge. The flow tube was constructed in the form of a U-tube. The ozone was deposited as a blue liquid film in the neighbourhood of the surface of the liquid nitrogen on the walls of the part of the U-tube, which was connected with the discharge tube. The oxygen atom decay in the U-tube was observed by measuring the production of ozone as the distance between the discharge tube (diameter: 5,2 cm) and the surface of the liquid nitrogen was varied. The decay is first order in atom concentration for the pressures p > 1 torr. But for the pressures below p = 1 torr near by the discharge tube we observed deviations from the law of decay In [O]₀/[O] = k·t for the currents of about i = 100 mA. This effect was attributed to the process From the extrapolation of an ozone production curve atom concentrations in the discharge have been obtained. The transition from the ?H”? form to the ?T”? form (striated, low average electric field) of the discharge [2] caused the dissociation to decrease rapidly. The highest dissociation (10%) was obtained in the ?H”? form at high currents (i = 120 mA) and low pressures (p = 0,60 torr). The yield of atomic oxygen per kilowatt hour of energy was measured as functions of pressure and gas flow rate for i = 100 mA and i = 50 mA.     

Zur Mikrowellendiagnostik stromstarker Entladungen mit Skineffekt. Teil 1: Feldverteilung,Oberflächenimpedanz und Strahlungstransport

Using the methods of microwave diagnostics in the case of a dense, cylindrical plasma column, a complex surface impedance and a mean noise temperature, due to the real part of this impedance may be obtained instead of electron density, collision-frequency and noise (electron-) temperature in the usual low density case. In this paper these quantities including the scin-effect are calculated for the axial-symmetric plasma mode of an inhomogeneous plasma column. The mean noise temperature is obtained using a new method based on relations between the corresponding wave-equation and the four pole equations. The result is a differential equation similar to the equation of radiation transfer, but without the well known restrictions of this tool (approximation of ray optics, low damping of the wave).     

Zur Reflexion und Transmission elektromagnetischer Wellen bei senkrechtem Einfall auf ebene Grenzflächen zwischen unterschiedlich absorbierenden Medien

On Reflection and Transmission of Electromagnetic Waves Propagating Perpendicular to Plane Surfaces between Different Absorbing Media Born and Ladenburg already in 1911 pointed out that to describe reflection and transmission of electromagnetic waves through a plane surface between two different absorbing media in addition to the usual Poynting vectors of the running waves the so called “mixed” Poynting vector is necessary to maintain the balance of energy on the boundary plane. The flow of energy connected with this vector always points toward the region of maximal wastage of this energy and is closely related to the spatial modulation of the energy consumption within the partially standing interference pattern between the incoming and the reflected wave. In almost all substances the energy absorption is caused by the electric field whereas practically a direct contribution from the magnetic field can be neglected. But taking account of these magnetic effects we may get a better understanding of the mixed Poynting vector. To that end we add to the second of the Maxwell equations a quantity analogous to the electric current term in the first Maxwell equation. The amplitude of the “mixed” Poynting vector then turns out to depend essentially on the ratio of the energy absorption by the electric and the magnetic field. To confirm this fact we consider a medium, which shows in addition to the usual electric losses also magnetic ones of comparable magnitudes. In such materials the resultant energy consumption is distributed more similar to the spatial distribution of the fieldenergy. As a result the amplitude of the mixed Poynting vector disappears if the percentage of energy absorption by the electric and the magnetic field and their energy densities themselves are made equal to each other.     

Eine neue Methode zur Bestimmung der Rauhigkeitsautokorrelationsfunktion von optischen Oberflächen

A New Method of Determining the Autocorrelation Function of Polished Optical Surfaces Starting with a general theory of light scattering a measuring procedure for determining the autocorrelation function of surface roughness of well polished substrates is deduced. In this method light intensity scattered into a fixed direction has to be measured in dependence on the dimensions of the scattering area. The results are tested for a glass surface polished by different methods.     

Desorptions- und Reaktionskinetik der Erdalkalien Calcium und Strontium mit Chlor an Wolfram. Teil I: Chemisches Gleichgewicht der Oberflächenreaktion M + Cl = MCl im stationären Zustand (M = Ca,Sr)

Desorption- and Reactionkinetics of the Alkaline Earth Elements Calcium and Strontium with Chlorine on a Tungsten Surface — Part I: Chemical Equilibrium of the Surface Reaction M + Cl ? MCl in the Steady State (M = Ca, Br) Utilizing positive and negative surface ionization the reaction M + Cl = MCl (M = Ca, Sr) was studied at a hot tungsten surface under steady state conditions. Comparing the results obtained either by simultaneous M- and Cl₂ -exposures or by MCl₂ -exposure the existence of chemical equilibrium could be confirmed for the reaction in the temperature interval 1600 K.2000 K; at higher temperatures this equilibrium can be disturbed considerably by the desorption of the reacting components. From the experimental results we obtained under conditions of chemical equilibrium the energy of dissociation of MCl-molecules in the gasphase (D = (3.9 ± 0.15) eV, D = (4.2 ± 0.15)eV) and in the case of a strong disturbance of the equilibrium the difference between the activation energies of desorption and of dissociation of MCl-molecules on the surface (? - D? = (1.6 ± 0.2) eV, ? - D? = (1.4 ± 0.2) eV).     

Theoretische Modelle des katodischen Brennflecks von Bogenentladungen. Teil I: Grundlagen

Presuppositions, theoretical basis, results and general experiences of numerical model calculations of quasi-stationary cathodic spots in (vacuum) arcs are summarized. The results (mainly related to copper cathodes) comprise the essential physical quantities of the cathode spot surface and (partially) of the cathode spot plasma, i.e. possible states of existence within the space of parameters. Especially, the dependence of these results on changes of the parameters and equations is investigated. Several examples are presented and interpreted. In any case, the surface roughness of the cathode is taken into account. Finally, the limitations of the model are discussed, and the great importance of non-stationary (e.g. explosive) processes within the arc spot is emphasized, though such processes are beyond the scope of this model. The paper is published in two parts. This first part comprises an introduction to several aspects of arc spot modeling, the discussion of the physical processes in cathode arc spots and the development of relevant equations to be used in the model.