Showing papers in "Physica Scripta in 1999"
TL;DR: In this article, the authors derived the general solution of a wave equation describing the dynamics of two-layer viscoelastic polymer materials of arbitrary thickness deposited on solid (quartz) surfaces in a fluid environment.
Abstract: We have derived the general solution of a wave equation describing the dynamics of two-layer viscoelastic polymer materials of arbitrary thickness deposited on solid (quartz) surfaces in a fluid environment. Within the Voight model of viscoelastic element, we calculate the acoustic response of the system to an applied shear stress, i.e. we find the shift of the quartz generator resonance frequency and of the dissipation factor, and show that it strongly depends on the viscous loading of the adsorbed layers and on the shear storage and loss moduli of the overlayers. These results can readily be applied to quartz crystal acoustical measurements of the viscoelasticity of polymers which conserve their shape under the shear deformations and do not flow, and layered structures such as protein films adsorbed from solution onto the surface of self-assembled monolayers.
1,455 citations
TL;DR: In this paper, the authors take a closer look on these simple solutions and compare them with some of the simulation data (Henderson et al to appear in Wave Motion) and find that the Ma breather and Peregrine solution may provide useful and simple analytical models for 'freak' wave events.
Abstract: Some breather type solutions of the NLS equation have been suggested by Henderson et al (to appear in Wave Motion) as models for a class of 'freak' wave events seen in 2D-simulations on surface gravity waves. In this paper we first take a closer look on these simple solutions and compare them with some of the simulation data (Henderson et al to appear in Wave Motion). Our findings tend to strengthen the idea of Henderson et al. Especially the Ma breather and the so called Peregrine solution may provide useful and simple analytical models for 'freak' wave events.
339 citations
TL;DR: The Vienna Atomic Line Data Base (VALD) as discussed by the authors contains about 600,000 entries for spectral lines with measured energy levels and includes tools for extracting data and references which are particularly suitable for spectrum synthesis and model atmosphere calculations.
Abstract: Atomic transition parameters are of fundamental importance for many aspects of astrophysical research. But this information is spread over an enormous variety of publications in the fields of, e.g., applied and atomic physics, chemistry, and astronomy. Moreover, they differ in parameters listed and physical units used, as well as in their relative and absolute accuracy. This unfortunate situation led us to create a set of both critically evaluated and more homogeneous lists of astrophysically important atomic transition parameters and of supporting extraction software. This new data base is called the "Vienna Atomic Line Data Base" (VALD) and contains about 600000 entries for spectral lines with measured energy levels. VALD includes tools for extracting data and references which are particularly suitable for astrophysical applications such as spectrum synthesis and model atmosphere calculations. They are described in papers by Piskunov et al (1995) and Kupka et al (1999). We describe in this paper the structure of VALD, present a summary of all available data sets, explain our ranking procedure, in particular for the case of recent data on Fe I and Fe II, and comment briefly on the specific retrieval tools. The electronic-mail interface VALD–EMS allows remote access to VALD and is now extended by the WWW interfaces: http://www.astro.univie.ac.at/~vald and http://www.astro.uu.se/~vald
159 citations
TL;DR: In this paper, the authors used an asymmetric double sigmoidal function to fit the experimental PL spectra, which can be interpreted to show the presence of spatial potential fluctuations in our samples.
Abstract: Photoluminescence (PL) measurements of CuIn1-xGaxSe2 (x = 0.5) single crystals grown by the vertical Bridgmann technique were made at temperatures ranging from 11 K to 200 K and with various excitation powers. At low temperatures only one asymmetric PL band (BT-band) is present at 1.23 eV. It has a steeper decline on the high-energy side and nearly temperature independent low-energy side. At higher temperatures (T > 140 K) the BB-band becomes visible at 1.31 eV. We used an asymmetric double sigmoidal function to fit the experimental PL spectra. The results of this fitting can be interpreted to show the presence of spatial potential fluctuations in our samples. Observed dependencies would seem to reveal that the BT band is indeed connected with the recombination of a free electron with a localized hole. It is shown that these relatively deep localized states are probably formed due to potential fluctuations in highly compensated material and are not connected with any particular acceptor defect. We show that this model conforms to most of the discovered dependencies.
123 citations
TL;DR: In this article, a new Boltzmann-like collision term including correlations is proposed, which yields the one-particle distribution function in the form of a generalised-Lorentzian resembling but not being identical with the so-called κ distribution frequently found in collisionless turbulent systems like space plasmas.
Abstract: A new kinetic theory Boltzmann-like collision term including correlations is proposed. In equilibrium it yields the one-particle distribution function in the form of a generalised-Lorentzian resembling but not being identical with the so-called κ distribution frequently found in collisionless turbulent systems like space plasmas. We show that this distribution function satisfies a generalised H-theorem, yields an expression for the entropy that is concave. Thus, the distribution is a "true" thermodynamic equilibrium distribution, presumably valid for turbulent systems. In equilibrium it is possible to construct the fundamental thermodynamic quantities. This is done for an ideal gas only. The new kinetic equation can form the basis for obtaining a set of hydrodynamic conservation laws and construction of a generalised transport theory for strongly correlated states of a system.
110 citations
TL;DR: In this article, the bound state energy eigenvalues and the corresponding wave functions of the deformed hyperbolic molecular potentials were obtained by the Nikiforov-Uvarov method.
Abstract: The bound state energy eigenvalues and the corresponding wave functions of the "deformed" Rosen-Morse and modified Rosen-Morse potentials have been obtained by the Nikiforov-Uvarov method (Buyukkilic et al 1997 Theor. Chim Acta. 98 192). The "deformed hyperbolic functions" that were introduced for the first time by Arai (1991 J. Math. Anal. Appl. 158 63) have been used. The energy eigenvalues of these "deformed hyperbolic molecular potentials" bring up the criteria for the shape invariance of the potentials according to the deformation parameter q, as well as bringing a bound for the value of the parameter.
104 citations
TL;DR: In this article, exact calculations of the nonrelativistic wave functions and energies of helium are reviewed, together with the lowest-order relativistic corrections, and the results are extended to the entire singly-excited spectrum of helium by means of asymptotic expansion (core polarization), and quantum defect methods.
Abstract: Essentially exact calculations of the nonrelativistic wave functions and energies of helium are reviewed, together with the lowest-order relativistic corrections. The results are extended to the entire singly-excited spectrum of helium by means of asymptotic expansion (core polarization), and quantum defect methods. Comparisons with high-precision experimental atomic transition frequencies then provide a measure of higher-order relativistic and quantum electrodynamic effects. Other applications are discussed, such as the determination of nuclear radii from the isotope shift, and measurement of the fine structure constant from fine structure splittings. Recent progress for the more difficult lithium problem is briefly reviewed.
103 citations
TL;DR: In this paper, the first observation of metal cluster dianions in the size range n = 16-30 has been reported. But the threshold appearance size is in good agreement with a simple charged sphere model.
Abstract: Singly charged gold cluster anions in the size range n = 16–30 have been captured, stored and size selected in a Penning trap. After application of an electron beam doubly charged gold cluster anions have been observed for 20 ≤ n ≤ 30. To our knowledge this is the first observation of metal cluster dianions. The threshold appearance size is in good agreement with a simple charged sphere model. The application of argon gas pulses simultaneously with the electron beam is found to increase the production rate by an order of magnitude.
69 citations
TL;DR: In this article, the bound state energy eigenvalues and corresponding wave functions of the deformed Poschl-Teller and Hyperbolic Kratzer-like potentials have been obtained by the Nikiforov-Uvarov method.
Abstract: In this study, the bound state energy eigenvalues and the corresponding wave functions of the deformed Poschl–Teller and Hyperbolic Kratzer-like potentials have been obtained by the Nikiforov–Uvarov method using the deformed hyperbolic functions (sinhq (x) ≡ ½(ex – qe-x), coshq (x) ≡ ½(ex + qe-x), sechq (x) ≡ 1/coshq (x) and tanhq (x) ≡ sinhq (x)/coshq (x)) that were introduced for the first time by Arai [J. Math. Anal. Appl. 158, 63 (1991)]. It is also observed that, the energy eigenvalues of these "new" type deformed hyperbolic potentials bring up the criteria for the shape invariance of the potentials according to the deformation parameter q.
69 citations
TL;DR: In this article, the authors extend the non-gaussian thermodynamic formalism of a non-Markovian medium to its most general form that allows for the formulation of a consistent thermodynamic theory.
Abstract: We extend the recently developed non-gaussian thermodynamic formalism [R.A. Treumann, Physica Scripta, 59, 19 (1999)] of a (presumably strongly turbulent) non-Markovian medium to its most general form that allows for the formulation of a consistent thermodynamic theory. All thermodynamic functions, including the definition of the temperature, are shown to be meaningful. The thermodynamic potential from which all relevant physical information in equilibrium can be extracted, is defined consistently. The most important findings are the following two: (1) The temperature is defined exactly in the same way as in classical statistical mechanics as the derivative of the energy with respect to the entropy at constant volume. (2) Observables are defined in the same way as in Boltzmannian statistics as the linear averages of the new equilibrium distribution function. This lets us conclude that the new state is a real thermodynamic equilibrium in systems capable of strong turbulence with the new distribution function replacing the Boltzmann distribution in such systems. We discuss the ideal gas, find the equation of state, and derive the specific heat and adiabatic exponent for such a gas. We also derive the new Gibbsian distribution of states. Finally we discuss the physical reasons for the development of such states and the observable properties of the new distribution function.
67 citations
TL;DR: In this article, the authors provide the background for this selection vis-a-vis the operating parameters expected during normal and off-normal conditions, and the reasons for the specific grades of armour materials are also described.
Abstract: The selection of the armour materials for the Plasma Facing Components (PFCs) of the International Thermonuclear Experimental Reactor (ITER) is a trade-off between multiple requirements derived from the unique features of a burning fusion plasma environment. The factors that affect the selection come primarily from the requirements of plasma performance (e.g., minimise impurity contamination in the confined plasma), engineering integrity, component lifetime (e.g., withstand thermal stresses, acceptable erosion, etc.) and safety (minimise tritium and radioactive dust inventories). The current selection in ITER is to use beryllium on the first-wall, upper baffle and on the port limiter surfaces, carbon fibre composites near the strike points of the divertor vertical target and tungsten elsewhere in the divertor and lower baffle modules. This paper provides the background for this selection vis-a-vis the operating parameters expected during normal and off-normal conditions. The reasons for the selection of the specific grades of armour materials are also described. The effects of the neutron irradiation on the properties of Be, W and carbon fibre composites at the expected ITER conditions are briefly reviewed. Critical issues are discussed together with the necessary future R&D.
TL;DR: An electron beam ion trap (EBIT) is under construction at the University of Freiburg as mentioned in this paper, which can be operated both as an ion trap and an ion source, and its design specifications will allow production of hydrogenic ions from even the heaviest elements.
Abstract: An electron beam ion trap (EBIT) is under construction at the University of Freiburg. It will be operated both as an ion trap and as an ion source, and its design specifications will allow production of hydrogenic ions from even the heaviest elements. It will be possible to extract and accelerate the ions to energies up to 350 kV/q.
TL;DR: In this article, reduced matrix elements, oscillator strengths, and transition rates are calculated for all allowed and forbidden 2s-2p electric dipole transitions in beryllium-like ions with nuclear charges ranging from Z = 4 to 100.
Abstract: Reduced matrix elements, oscillator strengths, and transition rates are calculated for all allowed and forbidden 2s–2p electric dipole transitions in berylliumlike ions with nuclear charges ranging from Z = 4 to 100. Many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start with a 1s2 Dirac–Fock potential and include all possible n = 2 configurations, leading to 4 odd-parity and 6 even-parity states. First-order perturbation theory is used to obtain intermediate coupling coefficents. Second-order MBPT is used to determine the matrix elements, which are evaluated for the 16 possible E1 transitions. The transition energies used in the calculation of oscillator strengths and transition rates are evaluated using second-order MBPT. The importance of virtual electron–positron pair (negative energy) contributions to the transition amplitudes is discussed.
TL;DR: In this article, the authors introduce the concept of the "polarized" distance, which distinguishes the orthogonal states with different energies, and give new inequalities for the known Hilbert-Schmidt distance between neighbouring states and express this distance in terms of the quasiprobability distributions and the normally ordered moments.
Abstract: We introduce the concept of the "polarized" distance, which distinguishes the orthogonal states with different energies. We also give new inequalities for the known Hilbert-Schmidt distance between neighbouring states and express this distance in terms of the quasiprobability distributions and the normally ordered moments. Besides, we discuss the distance problem in the framework of the recently proposed "classical-like" formulation of quantum mechanics, based on the sympletic tomography scheme. The examples of Fock's, coherent, "Schrodinger cats", squeezed, phase and thermal states are considered.
TL;DR: In this article, the electric quadrupole (E2) and magnetic dipole (M1) transitions in the nitrogen isoelectronic sequence (Z = 10 − 30) between the levels of the 1s22s22p3, 1s 22s2p4 and 1 s22p5 configurations are investigated.
Abstract: The electric quadrupole (E2) and magnetic dipole (M1) transitions in the nitrogen isoelectronic sequence (Z = 10–30) between the levels of the 1s22s22p3, 1s22s2p4 and 1s22p5 configurations are investigated. The results include wavelengths and radiative E2 and M1 transition probabilities. The stationary second-order many-body perturbation theory (MBPT) was used to account for the electron correlations. A non-local potential was used to calculate the radial part of the effective Hamiltonian. Relativistic corrections were included in the Breit–Pauli approximation. The lowest-order correlation corrections to the one-body part of the spin–orbit interaction operator were also included.
TL;DR: In this article, the authors describe modulational instability of the continuous-wave (cw) states in the dual-core nonlinear optical fiber with normal dispersion, and show that the asymmetric cw states (existing above the bifurcation point) exhibit MI at all values of the intensity.
Abstract: We describe modulational instability (MI) of the continuous-wave (cw) states in the dual-core nonlinear optical fiber with normal dispersion. We show that the asymmetric cw states (existing above the bifurcation point), as well as the symmetric ones (below the bifurcation point) exhibit MI at all values of the intensity (the instability of the symmetric cw states was known previously). Below the bifurcation, the MI's peak gain (with respect to the perturbation frequency, holding the intensity of the symmetric cw state constant) increases with intensity. Above the bifurcation – considering the asymmetric cw solution – the peak gain of this branch of the perturbation decreases with intensity; however, at the bifurcation point another branch goes unstable, its peak gain growing with intensity, and saturating at large intensities. The symmetric state's instability is non-oscillatory, while that of the asymmetric state is oscillatory. Direct simulations show that, in either case, MI eventually leads to full "optical turbulence," both the initial symmetric and initial asymmetric cw states giving rise to statistically symmetric turbulent states, which have equal average intensities in each core. Thus, the transition to turbulence restores the spontaneously broken symmetry.
TL;DR: In this article, Fourier transform spectrometers were used for measuring 294 Ba I lines and 52 Ba II lines with uncertainties in the range ±0.001 cm-1 to ± 0.01 cm- 1.
Abstract: Barium spectra emitted from hollow cathode discharges and recorded with Fourier transform spectrometers in the region 1700–31 000 A have been used for measuring 294 Ba I lines and 52 Ba II lines with uncertainties in the range ±0.001 cm-1 to ±0.01 cm-1. Energy level values have been derived from the measurements. The energy levels have been used for an improved determination of the Ba II ionization limit, giving the value 80686.30 ± 0.10 cm-1.
TL;DR: In this article, the initial stages of thin film growth and effect of doping with In, Ce and Eu were studied, and a spraying time of 30 s leads to continuous crystalline films with well-shaped grains with narrow granulometric distribution and mean grain size close to 35 nm.
Abstract: ZnO thin films were deposited by spraying of zinc acetate solution onto heated glass substrates at 670 K. Highly textured in the (002) direction undoped ZnO films, exhibiting exciton emission bands in photoluminescence spectra at 8 K, were grown. The initial stages of the thin film growth and effect of doping with In, Ce and Eu were studied. A spraying time of 30 s leads to continuous crystalline films with well-shaped grains with narrow granulometric distribution and mean grain size close to 35 nm. Depositing times longer than 2 min lead to the solid phase sintering process. Wide granulometric distribution of the grains in the range of 50–400 nm was found for undoped films. It is shown that the size and orientation of crystallites in the film, the optical and electrical properties of the films are determined by the dopant concentration. As a result dense ZnO films with high optical transmittance were produced.
TL;DR: In this article, reduced matrix elements and transition rates are calculated for all magnetic dipole (M1) transitions within 2l 2l' configurations and for some 2l3l' - 2l2l' transitions in Be-like ions with nuclear charges ranging from Z = 4 to 100.
Abstract: Reduced matrix elements and transition rates are calculated for all magnetic dipole (M1) transitions within 2l2l' configurations and for some 2l3l' - 2l2l' transitions in Be-like ions with nuclear charges ranging from Z = 4 to 100. Many-body perturbation theory (MBPT), including the Breit interaction, is used to evaluate retarded M1 matrix elements. The calculations start with a (1s)2 Dirac-Fock potential and include all possible n = 2 configurations, leading to 4 odd-parity and 6 even-parity states, and some n = 3 configurations. First-order perturbation theory is used to obtain intermediate coupling coefficients. Second-order MBPT is used to determine the matrix elements, which are evaluated for all 11 M1 transitions within 2l2l' configurations and for 35 M1 transitions between 2l3l' and 2l2l' states. The transition energies used in the calculation of oscillator strengths and transition rates are obtained from second-order MBPT. The importance of negative-energy contributions to M1 transition amplitudes is discussed.
TL;DR: In the Mk IIA divertor, the majority of the deposition occurs on cool surfaces many centimetres from the plasma, although with a line-of-sight to the vicinity of the inner strike point, and the average amount deposited per pulse is much greater than previously observed as discussed by the authors.
Abstract: Hydrogen retention in tokamaks is dominated by two mechanisms: implantation into plasma-facing surfaces and trapping in deposited layers. The amount of hydrogen implantation saturates at typically ~1021 atoms m-2, giving ~2 × 1023 atoms in the JET first wall (which is ~200 m2), whilst codeposition depends firstly on the quantity of carbon deposited, and secondly on the temperature history of the deposits. Generally, codeposition has dominated the retained H inventory in JET, which was typically ~1024 atoms. The installation of a divertor in JET has necessitated the presence of water-cooled components to protect the divertor field coils, whereas previously all plasma-facing components were normally at least 300°C. Thick carbon-based films are deposited on surfaces in the vicinity of the inner corner of the divertor on surfaces shadowed from the plasma. Because of the divertor cooling, these deposits are at low temperature and their H:C ratio is at least 0.5:1; as a result their contribution to the overall in-vessel inventory is increased. No comparable deposition is found at the outer divertor. In the Mk IIA divertor the majority of the deposition occurs on cool surfaces many centimetres from the plasma, although with a line-of-sight to the vicinity of the inner strike point, and the average amount deposited per pulse is much greater than previously observed. The number of carbon atoms forming the basis of the deposits amounts to several percent of the ion flux to the inner strike point. The build-up of material leads to spalling (probably on venting to air). The mechanism for the generation and transport of the carbon to form the films is unknown, but ELMs may have a role: it is important to fully understand the phenomenon because of the similarities between the JET and ITER divertor geometries.
TL;DR: The x-ray polarimeter at TEXTOR-94 is a unique diagnostic tool for the measurement of non-Maxwellian electron-velocity distributions, which can be produced in tokamak discharges in the presence of electric fields as discussed by the authors.
Abstract: Spectra of the 1s-2p resonance line of helium-like argon, Ar XVII, and the associated satellites in the narrow wavelength range from 3.9494 A to 3.9944 A have been observed at TEXTOR-94 with two high-resolution x-ray crystal spectrometers at Bragg angles near 54 degrees. Together, these instruments can be used as an x-ray polarimeter. The instruments are very sensitive to small amounts of argon; thus, a count rate of 4 × 105 photons/s, which corresponds to the maximum count rate capability of the presently used detectors, can be obtained for argon densities of less than 10-3 times the electron density, if the central electron temperature is about 1 keV. Up to 8192 spectra per discharge can be recorded allowing for the investigation of fast events during MHD activities. The instruments have been used to study the electron and ion behavior during internal sawtooth oscillations, which affect the confinement properties in the core of the plasma. The x-ray polarimeter at TEXTOR-94 is a unique diagnostic tool for the measurement of non-Maxwellian electron-velocity distributions, which can be produced in tokamak discharges in the presence of electric fields. First polarization measurements were performed during the flat-top phase in discharges with both pure ohmic heating and additional neutral-beam heating. These measurements showed that inhomogeneities in the emissivity profile can produce effects which look like polarization effects. No polarization was found when these source inhomogeneities were taken into account. The polarimeter is presently upgraded by an imaging x-ray crystal to facilitate polarization measurements. This will be important for the upcoming experiments with electron cyclotron heating at TEXTOR-94.
TL;DR: In this article, a quasi-continuous spectra of femtosecond laser plasma in the vicinity of multicharged H-like and He-like ion resonance lines were observed and interpreted for the first time.
Abstract: A new type of quasi-continuous spectra of femtosecond laser plasma in the vicinity of multicharged H-like and He-like ion resonance lines were observed and interpreted for the first time. It is shown that such spectra were generated by multicharged hollow ions and are caused by super high density conditions provided by a high contrast laser pulse.
TL;DR: In this paper, the authors explored the use of high power electronics in high frequency devices made from silicon carbide (SiC) in the mobile telecommunication revolution in which we currently live, and showed that the high power density achieved from such devices make them also suitable for base stations for mobile telephones.
Abstract: Silicon Carbide is fast emerging as a mature semiconductor. The unique combination of material properties offered by SiC will allow it to establish itself in applications where the ever dominant Si is approaching the physical (not technical) limits of it's operation. Three key areas will be explored in this paper: (i) High power electronics. SiC devices operating at several kV and capable of MW power handling will revolutionise the way electrical power is transmitted and made use of. Recent progress supported by ABB in Sweden suggests these breakthroughs will begin to play a key role soon after the turn of the century. (ii) High frequency devices made from SiC will also play an increasingly important part in the mobile telecommunication revolution in which we currently live. Northrop Grumman in the USA have demonstrated the transmission of digital TV using SiC based devices. The high power density achieved from such devices make them also suitable for base stations for mobile telephones. (iii) Finally we look at some examples of how SiC is being used to develop new types of sensors that can be used in extreme environments such as high temperatures, high pressures or corrosive environments. Feedback from such sensors is seen as essential to understanding how we effect the world around us and thereby how we can limit pollution.
TL;DR: In this paper, the formulae for electrostatic interaction between the configurations nlN + 2, nl N + 1n'l', nl nn' l'n'' s2 and the configuration nnN nn l'l'2n'' l'' are given.
Abstract: The formulae for electrostatic interaction between the configurations nlN + 2, nlN + 1n'l', nlNn'l'n''l'', nlNn'l'2, nlN – 1n'l'n'' s2 and the configuration nlN – 1n'l'2n''l'' are given. The formulae will be applied to the fine structure analysis of even configurations of the europium atom Eu I.
TL;DR: In this paper, the authors investigated the effect of temperature on the binding energy of a donor impurity located at the center of a spherical semiconductor AlxGa1-xAs/GaAs/AlxGa 1 -xAs quantum dot and found that the calculated binding energy at a low temperature of 4 K is increased by about 23% over that associated with a temperature near room temperature, 300K, for a quantum dot radius of 27 A.
Abstract: The present work investigates the effect of temperature on the binding energy of a donor impurity located at the center of a spherical semiconductor AlxGa1-xAs/GaAs/AlxGa1-xAs quantum dot. It is found that the calculated binding energy at a low temperature of 4 K is increased by about 23% over that associated with a temperature near room temperature, 300K, for a quantum dot radius of 27 A. This effect is due to the enhancement of the electron spatial probability density at low temperature.
TL;DR: In this article, the deuterium-to-carbon concentration ratio was in the range from 0.04 to 0.11 and around 0.2 for the sole tungsten and the twin limiter, respectively.
Abstract: Tungsten test limiters of mushroom shape and a plasma facing area of approximately 100 cm2 were exposed at the TEXTOR-94 tokamak to a number of deuterium fuelled discharges performed under various operation conditions. Two types of limiters were tested: a sole tungsten limiter and a twin limiter consisting of two halves, one made of tungsten and another of graphite. The exposed surfaces were examined with ion beam analysis methods and laser profilometry. The formation of some deposition zones was observed near the edges of the limiters. The deuterium-to-carbon concentration ratio was in the range from 0.04 to 0.11 and around 0.2 for the sole tungsten and the twin limiter, respectively. Significant amounts of the co-deposited tungsten and silicon atoms were found on the graphite part of the twin limiter indicating the formation of mixed W-C-Si compounds.
TL;DR: In this article, the planar symmetrical (n+1)-body problem in a Manev-type field is tackled, where the initial velocities form a vector field symmetrical with respect to the central mass.
Abstract: The planar symmetrical (n+1)-body problem in a Manev-type field (featured by a potential of the form α/r + β/r2) is being tackled. One proves that, if n equal masses are initially situated at the vertices of a regular polygon centered in the (n+1)-th mass (Maxwell's model for the rings of Saturn), and if the initial velocities form a vector field symmetrical with respect to the central mass, then the polygonal configuration is preserved all along the motion, but with variable side and with variable rotation around the centre. The motion of every mass relative to the centre is given by the solution of the Manev-type two-body problem. All possible behaviours of the polygonal solution are surveyed, and the equilibria of the problem are pointed out. One associates a restricted problem to them, for which the Jacobi integral is proved to exist.
TL;DR: In this paper, the Stark widths of the 3s-3p and 3p-3d transitions of singly ionized C, N, O, F and Ne have been measured and compared with other experiments and semiclassical and semi-empirical theoretical results in the plasma of a low-pressure pulsed arc.
Abstract: The Stark widths of the 3s–3p and 3p–3d transitions of singly ionized C, N, O, F and Ne have been measured and compared with other experiments and semiclassical and semiempirical theoretical results in the plasma of a low-pressure pulsed arc. The plasma electron densities were determined from the width of He II Pα line while the electron temperatures were measured from relative intensities of N II lines.
TL;DR: In this article, the average fragment sizes and average kinetic energies are determined as a function of the number of stabilised electrons stabilised by a single Xe25+ projectile, and the kinetic energies of the atomic fragments are used to estimate the charge state of the parent ion C60q+.
Abstract: C60-molecules are multi-ionised by Xe25+ projectiles at collision energies of 280 keV. The produced ions and fragments are analysed in coincidence with the charge state of the outgoing projectile ion. Intact molecular ions are formed in charge states at least up to q = 10; they are stable on a time scale of several µs. From the time-of-flight spectra, average fragment sizes and average kinetic energies are determined as a function of the number of electrons stabilised by the projectile. The kinetic energies of the atomic fragments are used to estimate the charge state of the parent ion C60q+. In the case of 11 stabilised electrons (Xe25+ → Xe14+), about 50 electrons are removed from the fullerene cage, which is in agreement with recent experimental results (Bernard et al, this volume).
TL;DR: In this paper, a capacitive silicon microphone with a low-stress bending membrane and a high-stressed backplate is fabricated by combining bulk and surface micromachining techniques.
Abstract: A capacitive silicon microphone has been fabricated. The component consists of two freestanding polysilicon membranes, a low-stress bending membrane and a high-stress backplate, which are separated by an air gap. Sound pressure changes the capacitance between the membranes. A backchamber is arranged by encapsulation and static pressure changes are prevented with small equalisation holes in the bending membrane. The component is fabricated combining bulk and surface micromachining techniques. Silicon substrates are etched in TMAH and sacrificial oxide between the membranes is etched in PSG-etch followed by freeze drying to prevent sticking. The measured acoustic sensitivity of the microphone with 1 × 1 mm2 membrane was 2 mV/Pa (1 kHz frequency) and the resolution 35 dB (A-weighted sound level).