Abweichungen von der Gleichgewichtsbesetzung der Ar-II-Terme in einem an der Oberfläche von Ferrelektrika erzeugten Plasma

A plasma obtained in argon near the surface of ferroelectric BaTiO₃ ceramics has been examined in this work. It was found that the population densities of the excited Ar II doublet levels are greater than those of the excited Ar II quartet levels. This fact is related to the specific conditions of argon atoms excitation in the electric field of the ferroelectric domains. There is a possibility of ionization with simultaneous excitation of the neutral argon atoms.     

Mikromagnetisch singuläre punkte in bubbles

The magnetization pattern of a vertical Bloch line in a bubble wall containing a singular point in its center is investigated by a variational method. Introducing a hypothetical intermediate structure, the energy of such a configuration can be separated into two parts: one which describes a local embedding energy for the singular point, and one which may be derived from the structure of the domain wall only. The results indicate that above a critical film thickness Bloch lines containing a singular point represent, in agreement with a prediction by Slonczewski, the energetically most favourable configuration.     

Über die Gleichgewichtsbesetzung der Zustände von O II

Experimental results concerning the density-dependent relative populations of two energetically different states of the singly ionized Oxygenatom are compared to theory. Opposed to the latter, the experiment gave relative populations consistent with the thermodynamic equilibrium assumption down to electron densities of 10¹⁶(cm^?3). The plasma was produced by a modifiedT-tube and the measured effect may be a peculiarity of the particular plasma investigated. The conclusion may be drawn that the plasma radiates in thermal equilibrium at much lower densities than theoretically expected. If a theoretical estimate ofGriem may be assumed formally correct, a correction factor of the order of ten can be applied. This granted, even the states of doubly ionized species may be assumed to be populated as in thermal equilibrium at densities exceeding 10¹⁷(cm^?3).     

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.     

Zur Theorie der parametrischen Anregung von elektrostatischen Oberflächenwellen in einer Plasmaschicht

Dispersion relations for electrostatic surface waves in a homogeneous plasma-layer which interacts with an external electric pumping field parallel to the boundaries are derived in the framework of the kinetic theory. The parametrically excited and purely growing instabilities are investigated. Electric threshold fields and growth rates for the instable surface modes are given. It can be shown that the minimum threshold for parametric excitation occurs for those modes which are symmetric about the midplane of the layer.     

Die Aktivierungsfläche bei der Versetzungsbewegung

The activation area for the motion of dislocations is deduced by means of thermodynamic theory of the transition state. Assuming an exponential dependence of the slip velocity as a function of the applied stress and using additional simple statements the activation area is obtained in terms of parameters, which can be determined experimentally. Further on it is shown that one has to distinguish between different definitions of the activation area.     

Verallgemeinerung der Methode der singulären Normallösungen für isotherme irreversible Vlasov-Systeme

Irreversible Vlasov systems, i.e. systems governed by a Vlasov-type kinetic equation including entropy-producing collision terms, are treated by the techniques of singular normal modes and singular integral equations using a new indirect method which renders possible a straightforward generalization of the Case formalism as developed originally for collision-free Vlasov plasmas. This method is in contrast to a more complex method given by the present authors for the first application of the singular normal mode expansion to irreversible Vlasov systems (1970). The linearized Vlasov operator supplemented by complete Bhatnagar-Gross-Krook collision integrals as the most important model collision terms is analyzed in detail for a nonrelativistic, nondegenerate, stationary electron gas with neutralizing positive ions and neutral particles without a magnetic field at constant temperature, generalizations for more complex irreversible Vlasov systems being possible. The key of the indirect method given is the introduction of a transformed electron distribution function containing as an additive term an integral over the usual distribution function.     

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.