bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anwendung der Betz-Petersohn-Methode auf ein Oberflächen-Diffusionsproblem
Authors: Wagner Wolf-Udo 
Published: March 2015

Considered are particles which are condensed homogeneously on a plane surface from the vapour phase. They are removed in circular or straight sinks. The edges of the sinks are partially masked by an array of small obstacles. The problem of surface diffusion is solved by a method of conformal
mapping following BETZ and PETERSOHN 1. The obstacles cause an increase of particle density in a step-like fashion. The amplitude of the step depends on the degree of masking. As long as the sinks are not completely masked the density step is comparatively small and superimposed on the density function of unmasked sinks. The particle flux remains unchanged up to complete masking of the sinks.
Light Mixing and the Generation of the Second Harmonic in a Plasma in an External Magnetic Field
Authors: Kegel Wilhelm H. 
Published: March 2015

The theory of light scattering in a plasma is extended by including an external electric field (e.g. the field of a laser beam) in calculating the density fluctuations. It is shown that in the presence of a time constant homogeneous magnetic field there arise density fluctuations with the frequency and the wave number of the external electric field. Expansions of the general expressions are obtained for the case that the frequency is large compared to the electron gyrofrequency. The special case that the external electric field is a transverse wave is discussed in detail.
The light of a second beam may be scattered by these forced density fluctuations. The scattered light has the sum and the difference frequency of the two light beams, i.e. light mixing occurs. In the framework of this theory the effect occurs only if the two beams are parallel. - If one considers the scattering of the same beam that forces the density fluctuations, the scattered light is the second harmonic
Messung der lokalen Elektronentemperatur und Elektronendichte in einem Θ-Pinch mittels der Streuung eines Laserstrahls
Authors: Kunze Hans-Joachim 
Published: March 2015

The development of light scattering by a plasma as a diagnostic tool is reported, which allows the local measurement of electron density and electron temperature. After a résumé of known theoretical results the feasibility of scattering experiments is discussed. The ratio of scattered radiation to plasma radiation is estimated.
The experimental setup is described. Using fiber optics, it was possible to measure the whole spectrum of scattered light by one pinch discharge only. Several types of obtained spectra are modified by collective effects between the particles in the plasma. The building up of the satellite lines in the spectra is found as well as the existence of a small central line, as was predicted by the theory. Absolute calibrations of intensities also show the decrease of the scattering cross-section.
From the spectra plasma parameters could be derived
Die Selbstdiffusionskoeffizienten des Antimons in Einkristallen
Authors: Cordes H. , Kim K. 
Published: March 2015

Mit einer Isotopenaustauschmethode wurden in Einkristallen die Selbstdiffusionskoeffizienten des Antimons parallel und senkrecht zur trigonalen Achse bestimmt. Die in einem Temperaturbereich von 500,0°C bis 630,2°C durchgeführten Messungen lassen sich folgendermaßen darstellen:
D⊥c = (0,10 ± 0,02) exp[ — (35,8 ± 0,3) 103/RT] cm2 sec-1,
D∥c = ( 56 ± 20) exp[ — (48,0 ± 0,5) 103RT] cm2 sec-1.
Struktur und thermisches Verhalten von Wachstumszwillingen in dünnen kubisch flächenzentrierten Metallschichten
Authors: Schlötterer H. 
Published: March 2015

Single crystal films prepared by evaporation of silver, gold, copper, and nickel on heated cleaved rocksalt crystals and polycrystalline films of silver, gold, copper, platinum, aluminum, and nickel have been studied by transmission electron microscopy and electron diffraction. By means of electron microscope dark-field image and selected area diffraction technique the existence of small growth twins in the films is shown. Extra spots observed in the electron diffraction diagram can be explained partly as spots of the four twin orientations, partly as arising from double diffraction of the (100) matrix orientation and of a twin orientation. In the case of polycrystalline films the double diffraction mechanism results in additional diffraction rings seeming not to belong to the normal face-centred cubic lattice. The assumption of an hexagonal phase or of stacking faults or of periodic lattice defects cannot explain all the extra spots and additional rings.
The changing diffraction contrast of thick and thin microtwins obviously depends on the different reflection conditions in the electron microscope. It is shown that it is very complicated to distinguish stacking faults from microtwins, but some criteria of distinction are given.
By means of a heating stage the single crystals have been heated in the electron microscope up to more than 1000 °C. The thermal behaviour of the twins has been studied in detail. It can be observed that up to 95% of the twins become invisible by transformation from the twin orientation to the (100) matrix orientation. It is concluded from the experiments that the transformation nucleates at the top or bottom of the thin films. Nevertheless more than 1013 twins and stacking faults per cm3 remain unchanged inspite of heating to temperatures near the melting point of the bulk metal.
Zur Molekülbewegung in Flüssigkeiten und Lösungen I
Authors: Kramer K. D. , Müller-Warmuth W. , Roth N. 
Published: March 2015

The magnetic proton relaxation behaviour of free radical solutions of diethylether and diethoxyethane has been studied by a nuclear-electron double resonance method. The dielectric relaxation in the solvents has also been determined from a study of the frequency dependance of the complex dielectric constant.
The motional properties of the spin-carrying molecules which govern the magnetic interactions between different spin species are described by the model of randomly diffusing hard spheres. The time dependence is assumed to result from a combination of the relative translational diffusion of the spheres and the random rotational motions of complexes of spheres. Expressions and curves are given for the nuclear electron coupling parameter of dynamic nuclear polarisation and its frequency dependence. The comparison with experimental data taken at four different frequencies corresponding to magnetic fields of 15, 175, 1070 and 3230 gauss confirms the absence of scalar interactions and yields limits for the predominating translational diffusion. Correlation times at different temperatures and distances of closest approach of spins are evaluated.
The dielectric studies in ether yield a single relaxation time which is attributed to the orientation of the molecule as a whole. Diethoxyethane has a spectrum of dielectric relaxation times. The dielectric relaxation times and also their activation energies are smaller than the correlation times obtained by magnetic measurements. The viscosity is more closely related to the translational diffusion of molecules than to the dielectric relaxation time. The results are discussed in terms of the different mechanisms of motion.
Zur partiellen Entmischung von Gas- und Isotopengemischen durch Verdichtungsstöße
Authors: Bier K. , Zeller R. 
Published: March 2015

Bei der freien Expansion von Gasgemischen tritt bekanntlich eine partielle Entmischung verschieden schwerer Komponenten auf, die im Übergangsbereich zwischen gasdynamischem und molekularem Strömungsverhalten am größten ist und die im wesentlichen mit der Druckdiffusion in dem auf der Strömungsrichtung senkrecht stehenden, stationären Druckgefälle des frei expandierenden Gasstrahls zu erklären ist. Frühere Untersuchungen über die Umkehrung der Entmischungsrichtung in überexpandierten Gasstrahlen haben darüberhinaus qualitativ gezeigt, daß ein entsprechender Entmischungseffekt auch bei der „sprunghaften“ Umlenkung einer Überschallströmung in einem schrägen Verdichtungsstoß zu beobachten ist.
In der vorliegenden Arbeit wird die Entmischung in einem schrägen Verdichtungsstoß, der in der Innenzone eines frei expandierenden Gasstrahls durch ein nadelförmiges Hindernis erzeugt wird, in Abhängigkeit von der Gasdichte und von den gaskinetischen Eigenschaften der Gemischkomponenten quantitativ untersucht. Es stellt sich heraus, daß der Entmischungsstrom in der Stoßfront unter gasdynamischen Strömungsbedingungen für ein binäres Gemisch innerhalb der Fehlergrenze proportional zum relativen Druckgradienten, zur relativen Massendifferenz und zum Produkt aus Teilchendichte und Diffusionskonstante (d. h. unabhängig von der Gasdichte) ist, wie dies auch für die normale Druckdiffusion zutrifft. Da bei den angewendeten Versuchsbedingungen in der Stoßfront im Mittel ein Druckanstieg um den Faktor 1,5 — 1,6 pro mittlere freie Weglänge vorliegen dürfte, deutet das Ergebnis darauf hin, daß der Gültigkeitsbereich für den allgemeinen Diffusionsansatz in der ersten Näherung der Gaskinetik anscheinend größer ist, als nach der Herleitung, die kleine relative Zustandsänderungen pro freie Weglänge voraussetzt, zu erwarten war.
Inter-Diffusion of Li-Isotopes in Liquid Lithium Metal
Authors: Ott A. , Lodding A. 
Published: March 2015

The inter-diffusion coefficient of 6Li and 7Li in liquid Li metal has been measured by a capillaryreservoir vacuum lock technique and by mass spectrometric analysis. For the temperature interval 195—450 °C and near-normal isotopic composition, the results can be represented by
D= (1.41 ±0.12) ·10-3 exp[— (2825 ± 90)/ (R T)].
Theoretical relations connecting diffusion and viscosity are well obeyed. Fair agreement is obtained with the COHEN-TURNBULL free volume theory, if Li* is the diffusing species.
Die Thermokraft einiger Zellen des Typs Cl2/ T geschmolzenes Clorid/ Τ+ΔΤ Cl2
Authors: Fischer W. 
Published: March 2015

The thermoelectric power of cells of the type Cl2 | T MClv, |T+ΔΤ Cl2 has been measured, using the molten salts LiCl, NaCl, KCl, RbCl, CsCl, AgCl and PbCl2. The entropies of transfer and the heats of transfer for the ions in the melt are calculated. It is shown, that the part containing the heats of transfer is small compared to the heterogeneous part of the thermopotential and that this result is in accordance with a “quasi lattice“ model describing transport processes in ion conductors proposed by WIRTZ (1943).
Theoretical relations between the thermoemectric power of such cells and cells of the type M | T MCIv, | Τ+
ΔΤ M (MCl = AgCl, PbCl2) are experimentally verified.
The Thermoelectric Power of the Molten Systems (Ag+Li)NO3, (Ag+Na)NO3, and (Ag+K)NO3
Authors: Sinistri Cesare 
Published: March 2015

In a silver electrodes thermocell the thermoelectric power ε0 at zero time of the molten salt mixtures (Ag+Li)NO3 and (Ag+Na)NO3 at the mean temperature of 340 °C, and of (Ag+K)NO3 at the mean temperature of 360 °C has been measured.
On the basis of these data the transport heats of lithium, sodium and potassium ions in their respective pure nitrates have been roughly evaluated. Moreover a thermodynamical ideal model for the molten salt mixtures in respect to the transport properties is suggested.
Selbstdiffusion und Diffusionsmechanismus in Wolfram
Authors: Neumann G. M. , Hirschwald W. 
Published: March 2015

Die Diffusion von Wolfram in polykristallinem Wolfram (Korngröße 0,1—0,2 mm) wurde im Temperaturbereich 1740 bis 2100°C mit Hilfe des radioaktiven Isotops Wolfram-185 untersucht. Die Diffusion verläuft in diesem Temperaturbereich hauptsächlich über Korngrenzen und läßt sich beschreiben durch die Beziehung
D=1,80·10-3 exp{ —93 100/ (R T) } .
Für die Diffusion bei hohen Temperaturen (T > 0,8 Tm) wird ein Diffusionsmechanismus über die Bildung und Wanderung von Doppelleerstellen diskutiert.
Die Zusammensetzung des Überschuß-Argon in Schwarzwälder Flußspäten
Authors: Lippolt H. J. 
Published: March 2015

The argon and potassium contents of eight fluorite samples with microinclusions from the Schwarzwald, Germany, were measured by isotope dilution technique. The samples contain .5 to 5 × 10-7 cc radiogenic Ar/g and there exists an approximate proportionality between the radiogenic and atmospheric argon component. In six samples the ratio Ar (rad) /Ar (total) at the time of mineral formation lies between .38 and .52 and probably represents the ratio in the mineral forming brine. These numbers are compatible with the argon ratios found in natural gases from bedrocks.
ELINSON and POLYKOVSKII claim argon contents in fluid inclusions of pegmatitic feldspar ten times higher than the radioactive decay of K40 in the lattice would produce. Assuming this excess occuring frequently in pegmatitic feldspar and the pertinent ε0-values > 0, there could be a considerable source of error for K-Ar-determinations of such minerals.
Untersuchungen an einem Überschallplasmastrahl mit axialem Strom
Authors: Ragaller Klaus 
Published: March 2015

Starting from a parallel jet concept the linearized magnetogasdynamic equations are solved for a supersonic free plasma jet with an axial current. The solution is given in terms of the magnetic pressure number. A critical magnetic pressure number depending on the MACH number is derived. Below this value standing periodic pressure waves occur, as in the gasdynamic case. For higher values the pressure distribution is non-periodic.
Experiments are performed with a supersonic argon jet. The MACH number is determined by the shock angle at a cone. The pressure distribution in the axis of the jet is measured by a pressure probe. The experimental results are consistent with the theoretical predictions.
Anomalous Collisionless Damping of Alf vén Waves in Inhomogeneous Plasmas
Authors: Winterberg F. 
Published: March 2015

It is shown that ALFVÉN waves in a collisionless plasma, permeated by an inhomogeneous magnetic field, are affected by a strong anomalous damping. This anomalous collisionless damping seems to correspond to collision-free LANDAU damping in homogeneous magnetic fields in a similar way as the anomalous viscous and OHMic damping of ALFVÉN waves propagating in inhomogeneous magnetic fields 1 corresponds to the ordinary collisional viscous and OHMic damping of ALFVÉN waves propagating in homogeneous magnetic fields.
It is found that the predicted collision-free anomalous damping will obey a law of the form exp{ — (t/τ)2} where the damping time τ depends on the wave-length, the temperature of the plasma, and the magnetic field gradient.
Starting from a simplified BOLTZMANN-VLASOV equation, valid for low frequency plasma waves 2, a LAPLACE transform is carried out with regard to the time dependence and an integral equation is derived for the mean plasma velocity. By the faltung theorem this integral equation can be FOURIER transformed into a differential equation for which a W.K.B. solution can be obtained. The inverse transforms can be carried out by making a simple analytic approximation for the W.K.B. solution which is valid over a large range of values.
The predicted anomalous damping of ALFVÉN waves is so strong that it may be useful for the purpose of heating a plasma up to high temperatures within a short time.
Einfluß der Geschwindigkeit von Edelgasionen auf die Emission von Sekundär-Elektronen
Authors: Boerboom A. J. H. , Schram B. L. , Kleine W. , Kistemaker J. 
Published: March 2015

By direct comparison of the signals of a particle multiplier and a Faraday cage at the collector end of a mass spectrometer, the secondary emission coefficients of a copper-berilium alloy were determined for single and multiply charged noble gas ions. The ions involved were He+ and He2+, 20Ne+ up to 20Ne3+, 22Ne+, Ar+ up to Ar5+, Kr+ up to Kr7+ and Xe+ up to Xe9+. The energy of the ions varied between 3 and 90 keV.
The secondary emission factors show an almost exact linear dependence on the velocity of the ions, with a threshold at 5.5 × 106 cm/s. The slopes are proportional to the square roots of the ion masses.
Die Bedeutung der Mesonenatome in Kernphysik und Elementarteilchenphysik
Authors: Backenstoss G. 
Published: March 2015

Aus mesonischen Atomspektren können genaue Mesonenmassen erhalten und elektromagnetische Eigenschaften des Myons (Vakuumpolarisation) geprüft werden. Ladungsverteilungen und Kernmomente sphärischer und deformierter Kerne werden mit Hilfe von Myonenatomen mit Genauigkeiten bestimmt, die denen anderer Methoden vergleichbar oder überlegen sind.
Pionenatome liefern direkte Aussagen über die Pion—Kern-Wechselwirkung.
On the Plastic Deformation of Pure Solid Lithium Sulfate and Lithium—Potassium Sulfate Mixtures
Authors: Augustsson Bengt , Lundén Arnold 
Published: March 2015

A simple rotational viscometer has been constructed for measurements at elevated temperatures in the region 109 - 2 × 1012 poise, and has been used to study the deformation of pure fcc lithium sulfate (temperature range 740-860°C) and mixtures of this salt with potassium sulfate. These substances resemble highly-viscous non-NEWTONian liquids, and for a given torque the apparent viscosity can be represented by the conventional relation η=η0 exp (Q/R T). For pure lithium sulfate, measurements with a torque of 19 × 107 dyne-cm gave the values η0= 4.24 × 10-4 poise and Q = 7.4 × 104 cal/mole for the two constants.
Two mixtures containing 1.0 and 2.2 mole-% K2SO4, respectively, were studied. In the homogeneous solid solution phase the viscosity showed a dependence on the thermal prehistory of the salt during the first few days at a given temperature. This effect was not detected for the pure lithium sulfate or for the two-phase region of the mixtures. The temperature dependence of the viscosity was less pronounced for the homogeneous phase than it was for the pure salt, while it was very great in the two-phase region. It is suggested that viscosity (or electrical conductivity) measurements should be a possible method to determine the position of the solidus curve for mixtures of this type.
Der Diffusionskoeffizient des Nickels im flüssigen Kupfer
Authors: Gerlach J. , Leidel B. 
Published: March 2015

Der Diffusionskoeffizient des Nickels im flüssigen Kupfer wurde zwischen 1150 und 1400°C bei verschiedenen Konzentrationen mit der Kapillar-Reservoir-Methode ermittelt. Die Temperaturabhängigkeit der Diffusionskoeffizienten bei verschiedenen Konzentrationen beschreiben folgende Gleichungen:
0,025% Nickel: D= (5,90 ± 0,8) · 10-3· exp { - (12960 ± 1100)/RT}
0,25 % Nickel: D=(2,31 ± 0,35) · 10-3· exp { - ( 7690 ± 900)/RT}
2,5 % Nickel: D= (1,79±0,15) ·10-2·exp{- ( 9900± 825)/RT}
3,25 % Nickel: D= (5,81 ±0,45) ·10-2 ·exp{- (12560±1000)/RT}
Die Diffusion von 210Pb und 210Bi in zwei flüssigen Blei-Zinn-Legierungen
Authors: Döge G. , Standke K. H. 
Published: March 2015

Die Diffusion von 210Pb und 210Bi wurde in den Schmelzen von Blei-Zinn-Legierungen mit 16 und 26 Atom-Proz. Blei mit Hilfe der Methode von ANDERSON und SADDINGTON 1 in Abhängigkeit von der Temperatur bestimmt. Die Arheniussche Darstellung der Temperaturabhängigkeit der Diffusion führt bei Legierungen mit 16 Atòm-Proz. Blei zu den Beziehungen:
DPb=8,55·10-4 exp(-3300/R T), DBi=5,03·10-4 exp(-2800/R T).
Für 26 Atom-Proz. Blei wurde erhalten:
DPb=1,57·10-4 exp(-1270/R T), DBi =2,14·10-4 exp(-1640/R T).
Die hier beschriebenen Messungen zeigen eine geringere Temperaturabhängigkeit der Diffusionskoeffizienten in den beiden Legierungen als in den reinen Legierungskomponenten. Es wird darauf hingewiesen, daß ein solches Ereignis, das auch bei früheren Untersuchungen der Selbstdiffusion in den Schmelzen anderer eutektischer Legierungssysteme gefunden wurde, qualitativ gedeutet werden kann, wenn man von den Ergebnissen neuerer Untersuchungen über die Wärmebewegung in Flüssigkeiten ausgeht und für die hier in Betracht kommenden Systeme in der flüssigen Phase Strukturen annimmt, die dem Sauerwaldchen Ε-Typ entsprechen.
Mischungsverhalten von Palladiumlegierungen des Zwischengittertyps und des Substitutionsgittertyps
Authors: Brodowsky H. 
Published: March 2015

A close analogy is shown to exist between the excess potential of an interstitial solute, such as hydrogen in palladium, and the difference of the excess potentials of the components of a substitutional alloy, such as silver/palladium. The deviations from ideal behaviour of both systems can be interpreted in terms of a filling up of the 4d- and 5s-electron bands and in terms of an elastic lattice distortion. In the case of palladium alloys, a separation into the two parts is possible, because the Fermi energy rises only negligibly as the valence electrons of silver or hydrogen enter the 4d-band with its high density of states. At low silver or hydrogen concentration, the excess potentials can thus be entirely attributed to the elastic interactions.
According to measurements of the palladium activities by Schmahl, a misfit energy of 950 cal/mole is estimated for an alloy of 50% silver at 700°C. In addition, an energy of attraction of - 660 cal per mole pairs and a pair surplus of 4% above the random number of pairs is obtained. The density of states in the 5s-band is calculated to be 0.9 electrons per eV, in good agreement with the value from hydrogen absorption measurements.
Gravitationsinstabilitäten eines Plasmas bei differentieller Rotation
Authors: Ebert R. 
Published: March 2015

In this paper an instability calculation is given for an axially symmetric gas distribution which has a differential rotation and in which a magnetic field is present. It is a generalization of similar calculations given by CHANDRASEKHAR and BEL and SCHATZMAN. The generalization becomes necessary for the study of problems of the formation of planetary systems, and star formation.
The instability conditions and the critical wave lengths are calculated for plane-wave-like disturbances. For disturbances running perpendicularly to the axis of rotation instability can occur only if the gas density exceeds a critical value which depends on the differential rotation at the considered distance only as long as pressure gradients and gradients of the magnetic field strength are negligible. If the gas density exceeds this critical value the shortest unstable wave length is proportional to the square root of vT2+vB2, where vT means the velocity of sound and vB the ALFVÉN-velocity.
For disturbances running parallel to the axis of rotation in addition to the JEANS instability a new type of instability occurs due to the simultaneous action of the magnetic field and the differential rotation; for rigid rotation this instability vanishes.
Thermal Diffusion in Molten Binary Mixtures of Silver Nitrate with Alkali Nitrates
Authors: Backlund Villy , Dupuy Josette , Gustafsson Silas , Lundén Arnold 
Published: March 2015

Thermal diffusion in the molten systems LiNO3—AgNO3, KNO3—AgNO3, RbNO3—AgNO, and CsNO3—AgNO3 was detected by means of chemical analysis. Two types of cells were used: the elementary effect was measured directly in cells with vertical temperature gradients, and the coefficient of thermal diffusion (D') was estimated from the steady-state separation obtained in convection cells (horizontal temperature gradient). A discussion of possible sources of error shows for both methods that the results might be systematically lower than corresponding to ideal conditions. In all systems AgNO3 was enriched at the cold side. There are indications that the SORET-coefficient varies with the composiiton of the mixture and the temperature. Thus for the LiNO3— AgNO3 system, depending on the conditions, the SORET coefficient ranged from 2 × 10-3 to 5.5 × 10-3 degr.-1, while it was about 1.8 × 10-3-5 degr.-1 over a wide concentration range for the KNO3—AgNO3 system, and about 1.3 × 10-3 degr.-1 over the investigated ranges for the RbNO3—AgNO3 and CsNO3—AgNO3 systems.
Also isotope effects were measured with the convection cell, giving SoRET-coefficients of the order of 10-5 to 4 × 10-5 degr.-1 for 6Li—7Li as well as for 39K—-41K, which is in agreement with previous investigations.