Showing papers in "Physica Scripta in 2006"
TL;DR: In this article, an analogy of Fano resonance in quantum interference to classical resonances in the harmonic oscillator system is presented, which has a manifestation as a coupled behaviour of two effective oscillators associated with propagating and evanescent waves.
Abstract: We present an analogy of Fano resonances in quantum interference to classical resonances in the harmonic oscillator system. It has a manifestation as a coupled behaviour of two effective oscillators associated with propagating and evanescent waves. We illustrate this point by considering a classical system of two coupled oscillators and interfering electron waves in a quasi-one-dimensional narrow constriction with a quantum dot. Our approach provides a novel insight into Fano resonance physics and provides a helpful view in teaching Fano resonances.
363 citations
TL;DR: In this article, the two-dimensional Ginzburg-landau equation (GLE) was obtained from basic equations by a linear stability analysis, and the soliton solution classes to the elliptic and hyperbolic GLE were obtained by applying the function transformation method.
Abstract: The two-dimensional Ginzburg–Landau equation (GLE) is obtained from basic equations by a linear stability analysis. This equation governs the evolution of slowly varying envelopes of periodic spatio-temporal patterns related to Rayleigh–Benard convective instabilities. In addition, the phase instabilities of the complex GLE (CGLE) with quintic and space-dependent cubic terms modelling the Eckhaus and zigzag convective instabilities are reported. We find soliton solution classes to the elliptic and hyperbolic CGLE, by applying the function transformation method. The two-dimensional CGLE is transformed to a sine-Gordon equation, a sinh-Gordon equation and other equations, which depend only on one function χ. The general solution of the equation in χ leads to a general soliton solution of the two-dimensional CGLE. The obtained solutions contain some interesting specific solutions such as plane solitons, N multiple solitons and propagating breathers. We also discuss the soliton stability of the CGLE.
120 citations
TL;DR: In this article, the dispersion relation of dust-acoustic waves is modified while taking into account these distribution functions, and it is found that in the limit (i) r = 0, q → ∞ and (ii) κ→ ∞, the expressions of the current modified with (r, q) and kappa distributions reduce to the Maxwellian current.
Abstract: Dust grains immersed in a plasma can exhibit charge fluctuations in response to the oscillatory plasma currents flowing onto them. The fluctuation electrodynamics of dusty plasmas are determined by taking into account the dynamics of charging processes associated with plasma currents. Expressions for the charging currents are derived using kappa and generalized (r, q) distribution functions. The dispersion relation of dust-acoustic waves is modified while taking into account these distribution functions. Further, it is found that in the limit (i) r = 0, q → ∞ and (ii) κ → ∞, the expressions of the current modified with (r, q) and kappa distributions reduce to the Maxwellian current.
97 citations
TL;DR: The main idea behind this work is the use of the well-known Adomian decomposition method, and in this technique, the solution is found in the form of a rapid convergent series.
Abstract: In this paper, a method for solving multipoint boundary value problems is presented. The main idea behind this work is the use of the well-known Adomian decomposition method. In this technique, the solution is found in the form of a rapid convergent series. Using this method, it is possible to obtain the solution of the general form of multipoint boundary value problems. The Adomian decomposition method is not affected by computation round off errors and one is not faced with the necessity of large computer memory and time. To show the efficiency of the developed method, numerical results are presented.
96 citations
TL;DR: In this paper, a modified version of the generalized Lorentzian distribution function, referred to as the (r, q) distribution, has been employed to derive the shielding distance with a modified power-law.
Abstract: In the present paper, comparison of characteristic shielding distance is determined by using a non-Maxwellian plasma. A modified version of the generalized Lorentzian distribution function, which is referred to as the (r, q) distribution, has been employed to derive the shielding distance with a modified power-law. The most surprising feature of a plasma containing superthermals is the strong dependence of plasma Debye length λD on spectral indices κ, r and q. It is observed that these spectral indices frustrate the Debye shielding distance. In the case of kappa, it is much smaller than that found for a Maxwellian plasma. We adopt the (r, q) distribution because it gives better data fit results, especially when there are shoulders in the profile of the distribution function along with a high-energy tail.
93 citations
TL;DR: In this article, a mix of several different plasma-facing materials is proposed in ITER to optimize the requirements of areas with different power and particle flux characteristics (i.e., Be for the first wall, CFC for the divertor strike point tiles and W elsewhere in a divertor).
Abstract: Designing the interface between a thermonuclear plasma and the solid material environment is arguably one of the highest technical challenges of ITER and of the successful development of future fusion power reactors. Carbon-based materials are recognized to have superior thermomechanical properties and do not melt, but they retain high levels of tritium by co-deposition with eroded carbon that could severely constrain plasma operations. A carbon-fibre-composite (CFC) divertor target in ITER would survive long enough only with methods of mitigation/suppression of large edge localised modes (ELMs). Metallic materials, such as tungsten, would avoid the tritium retention issue, but melt layer losses due to large ELMs and disruptions may lead to severe damage and unacceptably short lifetimes. Maintaining plasma purity with high-Z materials remains a concern. A mix of several different plasma-facing materials is proposed in ITER to optimize the requirements of areas with different power and particle flux characteristics (i.e., Be for the first wall, CFC for the divertor strike point tiles and W elsewhere in the divertor). However, this will inevitably lead to cross-material contamination and the formation of material mixtures, whose behaviour remains uncertain and requires further investigation. Some of the most outstanding plasma–wall interaction problems that are still at issue in the design of ITER are briefly discussed in this paper, together with prospects for their resolution, by either R&D or design changes and/or dedicated operation provisions. They include: (i) plasma thermal loads and material damage during type I ELMs and disruptions, and prospects for mitigation, (ii) control of co-deposited tritium inventory in the carbon films, (iii) effects of mixed-materials and (iv) plasma operation with tungsten plasma-facing components. Directions and priorities of future research are proposed to narrow the remaining uncertainties and improve confidence in solutions in these areas.
89 citations
TL;DR: In this paper, the variational iteration method is applied to an initial value problem of parabolic type and the results of this method are the same as with the results obtained by the Adomian decomposition method.
Abstract: This paper applies the variational iteration method to an initial value problem of parabolic type. This method is based on the use of Lagrange multipliers for identification of optimal values of parameters in a functional. This method is a powerful tool for solving various kinds of problems. Employing this technique, it is possible to find the exact solution or an approximate solution of the problem. Using the variational iteration method of He, a rapid convergent sequence is produced which tends to the exact solution of the problem. The results of this method are the same as with the results obtained by the Adomian decomposition method. The fact that this technique solves nonlinear equations without using Adomian polynomials can be considered as an advantage of this method over the Adomian decomposition procedure. The linear and nonlinear cases of the Fokker–Planck equation are considered and solved using the variational iteration method. To show the efficiency of the variational iteration method, several examples are presented.
88 citations
TL;DR: In this article, the Sn IX-Sn XII spectra excited in a vacuum spark have been analyzed in the 130-160 A wavelength region, based on the energy parameter extrapolation in the isonuclear Sn VI-VIII and Sn XIII-XIV sequence.
Abstract: The Sn IX–Sn XII spectra excited in a vacuum spark have been analysed in the 130–160 A wavelength region. The analysis was based on the energy parameter extrapolation in the isonuclear Sn VI–VIII and Sn XIII–XIV sequence. 266 spectral lines belonging to the 4dm–(4dm−14f+4p54dm+1) (m=6–3) transition arrays were classified in the Sn IX–Sn XII spectra for the first time. All 18 level energies of the 4d3 configuration and 39 level energies of the strongly interacting 4d24f and 4p54d4 configurations were established in the Sn XII spectrum. The energy differences between the majority of the 4dm levels and about 40 levels of the 4dm−14f+4p54dm+1 configurations were determined in each of the Sn IX, Sn X and Sn XI spectra (m=6–4). As a result, all intense lines were classified in the 130–140 A region relevant to the extreme ultraviolet (EUV) lithography. It was shown that the most of the intense lines in the 2% bandwidth at 135 A belong to the transitions in the Sn XI–Sn XIII spectra.
75 citations
TL;DR: In this article, the dynamics of macro-particles forming two-dimensional (2D)-fluid-like structures is numerically studied for pair potentials of Yukawa type, and the parameters responsible for the phase state and transport processes are determined and investigated.
Abstract: Dynamics of macro-particles forming two-dimensional (2d)-fluid-like structures is numerically studied for pair potentials of Yukawa type. The parameters responsible for the phase state and transport processes are determined and investigated. Comparison of obtained results with data of numerical investigations for 3d Yukawa systems is presented.
68 citations
TL;DR: In this article, the first and second laws of thermodynamics are employed in order to study the inherent irreversibility of a gravity driven non-Newtonian Ostwald-de-Waele power law liquid film along an inclined isothermal plate.
Abstract: In this paper, the first and second laws of thermodynamics are employed in order to study the inherent irreversibility of a gravity driven non-Newtonian Ostwald-de-Waele power law liquid film along an inclined isothermal plate. Based on some simplified assumptions, the governing equations are obtained and solved analytically. Expressions for fluid velocity, temperature, volumetric entropy generation numbers, irreversibility distribution ratio and the Bejan number (Be) are also determined.
68 citations
TL;DR: In this article, a new approximation scheme was proposed to obtain analytic expressions for the bound state energies and eigenfunctions of Yukawa-like potentials, which were in excellent agreement with the accurate numerical values reported in the literature.
Abstract: We propose here a new approximation scheme to obtain analytic expressions for the bound state energies and eigenfunctions of Yukawa-like potentials. The predicted energies are in excellent agreement with the accurate numerical values reported in the literature.
TL;DR: In this article, the authors present an overview on the materials development and joining, the testing of PFMs and components, and the analysis of the neutron irradiation induced degradation in D-T-burning fusion devices.
Abstract: The plasma exposed components in existing and future fusion devices are strongly affected by the plasma material interaction processes. These mechanisms have a strong influence on the plasma performance; in addition they have major impact on the lifetime of the plasma facing armour and the joining interface between the plasma facing material (PFM) and the heat sink. Besides physical and chemical sputtering processes, high heat quasi-stationary fluxes during normal and intense thermal transients are of serious concern for the engineers who develop reliable wall components. In addition, the material and component degradation due to intense fluxes of energetic neutrons is another critical issue in D-T-burning fusion devices which requires extensive R&D. This paper presents an overview on the materials development and joining, the testing of PFMs and components, and the analysis of the neutron irradiation induced degradation.
TL;DR: In this paper, a self-similar unsteady flow behind a strong exponential shock driven out by a piston moving with time according to an exponential law is investigated, where the medium is assumed to be a mixture of small solid particles and a perfect gas.
Abstract: One-dimensional self-similar unsteady flow behind a strong exponential shock driven out by a piston moving with time according to an exponential law is investigated. The medium is assumed to be a mixture of small solid particles and a perfect gas. In order to get some essential features of the shock propagation, small solid particles are considered as pseudo-fluid and it is assumed that the equilibrium flow condition is maintained in the flow-field, and that the viscous-stress and heat conduction of the mixture are negligible. Solutions are obtained, in both cases, when the flow between the shock and the piston is isothermal or adiabatic. It is found that the assumption of zero temperature gradient brings a profound change in the density distribution as compared to that of the adiabatic case. Effects of a change in the mass concentration of the solid particles in the mixture Kp and the ratio of the density of solid particles to that of initial density of the gas G1 are also obtained.
TL;DR: In this article, the determination of neutrino oscillation parameters within the three-flavour framework was presented, including the first results from the MINOS long-baseline experiment.
Abstract: I summarize the determination of neutrino oscillation parameters within the three-flavour framework from world neutrino oscillation data with a date of May 2006, including the first results from the MINOS long-baseline experiment. It is illustrated how the determination of the leading 'solar' and 'atmospheric' parameters, as well as the bound on θ13 emerge from an interplay of various complementary data sets. Furthermore, I discuss possible implications of sub-leading three-flavour effects in present atmospheric neutrino data induced by Δm221 and θ13 for the bound on θ13 and non-maximal values of θ23, emphasizing, however, that these effects are not statistically significant at present. Finally, in view of the upcoming MiniBooNE results I briefly comment on the problem to reconcile the LSND signal.
TL;DR: In this article, an electrostatic streaming instability in a plasma composed of positively and negatively charged dust is considered, where there are two clouds of oppositely charged dust that stream through each other.
Abstract: We consider an electrostatic streaming instability in a plasma composed of positively and negatively charged dust. It is assumed that there are two clouds of oppositely charged dust that stream through each other. Application to the Martian dust devil environment, where the dust can become charged due to triboelectricity, is discussed.
TL;DR: A theoretical scheme for quantum secure direct communication (QSDC) is proposed in this paper, where a three-qubit symmetric W state functions as a quantum channel and two legitimate communicators can transmit their secret information using quantum teleportation and local measurements.
Abstract: A theoretical scheme for quantum secure direct communication (QSDC) is proposed, where a three-qubit symmetric W state functions as a quantum channel. Two legitimate communicators can transmit their secret information by using quantum teleportation and local measurements.
TL;DR: In this article, the exact solutions of the Klein-Gordon equation with equal scalar and vector ring-shaped potentials were presented, and they were shown to be the same as in this paper.
Abstract: We present the exact solutions of the Klein–Gordon equation with equal scalar and vector ring-shaped potentials.
TL;DR: In this paper, two-dimensional numerical fluid turbulence simulations demonstrating the formation and radial propagation of blob structures in toroidally magnetized plasmas are presented and analyzed in detail.
Abstract: Two-dimensional numerical fluid turbulence simulations demonstrating the formation and radial propagation of blob structures in toroidally magnetized plasmas are presented and analysed in detail. A salient feature of the model is a linearly unstable edge plasma region with localized sources of particles and heat, which is coupled to a scrape-off layer with linear damping terms for all dependent variables corresponding to transport along open magnetic field lines. The formation of blob structures is related to profile variations caused by bursting in the global turbulence level, which is due to a dynamical regulation by self-sustained differential rotation of the plasma layer. Radial propagation of the blob structures follows from a vertical charge polarization due to magnetic guiding centre drifts in the toroidally magnetized plasma. Statistical analysis of the particle density, radial electric drift and the radial turbulent particle flux reveals asymmetric conditional waveforms with a steep front and a trailing wake and positively skewed and flattened probability distributions, in agreement with recent experimental investigations. Coarse graining and spectral analysis further indicate the presence of long-range correlations in the particle density fluctuations. Finally, conditional statistics of the particle flux demonstrates the intermittency of the turbulent plasma transport and the quasi-periodic apparency of blob structures due to bursting in the global turbulence level.
TL;DR: In this paper, a review of the physical mechanism for baroclinic vorticity generation and convective motions in stratified fluids is given, emphasizing its relation to interchange motions of non-uniformly magnetized plasmas.
Abstract: In this contribution some recent investigations of two-dimensional thermal convection relevant to ordinary fluids as well as magnetized plasmas are reviewed. An introductory discussion is given of the physical mechanism for baroclinic vorticity generation and convective motions in stratified fluids, emphasizing its relation to interchange motions of non-uniformly magnetized plasmas. This is followed by a review of the theories for the onset of convection and quasi-linear saturation in driven-dissipative systems. Non-linear numerical simulations which result in stationary convective states reveal the process of laminar scalar gradient expulsion, leading to the formation of temperature plumes and vorticity sheets. These dissipative structures are demonstrated to result in temperature profile consistency and power law transport scaling far from the threshold. The last part of this paper deals with the generation of differential rotation by fluctuating motions through tilting of the convective structures. The role of kinetic energy transfer and shearing due to differential advection is pointed out. Numerical simulations for strongly driven systems reveal turbulent states with a bursty behaviour of the fluctuation level which is associated with relaxation oscillations in the kinetic energy of the azimuthally mean flows. This leads to a state of large-scale intermittency manifested by exponential tails in the single-point probability distribution function of the dependent variables. The global bursting is interpreted in terms of a predator–prey regulation from the point of view of energetics. Finally, a discussion is given of the relevance of these phenomena to a variety of magnetized plasma experiments.
TL;DR: In this paper, the authors outline recent developments in and the growing need for laboratory astrochemical measurements, focusing primarily on the utility of multi-electrode ion trapping methods for addressing key problems in reaction dynamics and their applications towards gaining a better understanding of the physicochemical driving forces behind compositional development in interstellar and circumstellar environments.
Abstract: In this paper, we outline recent developments in and the growing need for laboratory astrochemical measurements. After a short review on experimental methods, we focus primarily upon the utility of multi-electrode ion trapping methods for addressing key problems in reaction dynamics and their applications towards gaining a better understanding of the physicochemical driving forces behind compositional development in interstellar and circumstellar environments. Temperature variable trapping techniques, combined with lasers and molecular beams are unique tools for studying state specific reactions, for ion spectroscopy and for investigating the structure and stability of complex charged objects as a function of their internal energy. Particular emphasis is given to reactions with hydrogen atoms and molecules, H–D exchange leading to isotopic fractionation, problems in hydrocarbon ion chemistry and association chemistry in rarefied environments. In the outlook, we discuss the future needs in astrochemistry in order to pave the way towards understanding the next generation of sophisticated astronomical observations and to prepare for them.
TL;DR: A detailed study of cloud-to-ground (CG) lightning flashes over Sweden was carried out for the period 1987-2000 using data obtained from the Swedish lightning-locating network as mentioned in this paper.
Abstract: A detailed study of the characteristics of cloud-to-ground (CG) lightning flashes over Sweden was carried out for the period 1987–2000 using data obtained from the Swedish lightning-locating network. Results are presented by analysing over half a million lightning ground flashes. The average variation of the annual mean of the total number of flashes was found to be 37%. About 12% of the CG flashes were positive flashes and their average variation about the annual mean was 26%. The average peak currents were fairly constant over the years with variations as little as 4% for negative flashes and 5% for positive flashes. The average peak current values for negative and positive flashes were −29.90 and +63.97 kA respectively. A correlation between the mean monthly flash count and percentage of positive flashes was seen. A similar relationship is seen with the mean monthly flash count and the peak currents for both polarities. In general, high flash density and high peak currents were observed in the southern part of Sweden where most of the major cities are located. Flash densities exceeding 0.4 flashes km−2 were observed for several large cities. The maximum flash rate of 32 flashes h−1 within a 10 km radius was seen in Jonkoping (14.18°E, 57.78°N) in the province of Smaland.
TL;DR: A numerical technique that has recently been developed to automatically assign and fit high-resolution spectra and makes use of genetic algorithms (GA) is described.
Abstract: This paper describes a numerical technique that has recently been developed to automatically assign and fit high-resolution spectra. The method makes use of genetic algorithms (GA). The current algorithm is compared with previously used analysing methods. The general features of the GA and its applications in automated assignments is discussed. In a number of examples the successful application of the technique is demonstrated.
TL;DR: In this article, two theorems on the Riemannian geometrical constraints on vortex magnetic filaments acting as dynamos in (MHD) flows are presented.
Abstract: Two theorems on the Riemannian geometrical constraints on vortex magnetic filaments acting as dynamos in (MHD) flows are presented. The use of Gauss–Mainard–Codazzi equations allows us to investigate in detail the influence of curvature and torsion of vortex filaments in the MHD dynamos. This application follows closely previous applications to Heisenberg spin equation to the investigations in magnetohydrostatics given by Schief (2003 Plasma Phys. J. 10 2677). The Lorentz forces on vortex filaments are computed and the ratios between the forces along different directions are obtained in terms of the ratio between the corresponding magnetic fields which also equals the ratio between the Frenet torsion and vortex line curvature. A similar relation between Lorentz forces, magnetic fields and twist, which is proportional to total torsion integral, has been obtained by Ricca (2005 Fluid Dyn. Res. 36 319) in the case of inflexional disequilibrium of magnetic flux tubes. This is due to the fact that the magnetic vortex lines are a limiting case of the magnetic flux tubes when the length of the tube is much greater than the radius of the tube. The magnetic helicity equation of the filament allows us again to determine the magnetic fields ratio from Frenet curvature and torsion of the vortex lines. Recently, Schekochihin et al (2001 Phys. Rev. E 65 016305) obtained a similar relation between the ratios of magnetic field components by using a detailed analysis of the statistics of curvature. However, in their work no reference is made to torsion or helical vortex filaments.
TL;DR: Aharonov and Vaidman as mentioned in this paper showed that the Bohm interpretation gives a straightforward account of the behaviour of the particle without resorting to such a radical explanation, and that if the BI is used correctly, it gives a local explanation, which corresponds exactly to the standard quantum mechanics explanation offered by ESSW.
Abstract: The delayed-choice experiments of the type introduced by Wheeler and extended by Englert, Scully, Sussmann and Walther (ESSW) (1992 Z. Naturf. a 47 1175–86), and others, have formed a rich area for investigating the puzzling behaviour of particles undergoing quantum interference. The surprise provided by the original delayed-choice experiment led Wheeler to the conclusion that 'no phenomenon is a phenomenon until it is an observed phenomenon', a radical explanation which implied that 'the past has no existence except as it is recorded in the present'. However Bohm et al (1985 Nature 315 294–97) have shown that the Bohm interpretation (BI) gives a straightforward account of the behaviour of the particle without resorting to such a radical explanation. The subsequent modifications of this experiment led both Aharonov and Vaidman (1996 Bohmian Mechanics and Quantum Theory: An Appraisal ed J T Cushing, A Fine and S Goldstein (Dordrecht: Kluwer) pp 141–54) and ESSW to conclude that the resulting Bohm-type trajectories in these new situations produce unacceptable properties. For example, if a cavity is placed in one arm of the interferometer, it will be excited by a particle travelling down the other arm. In other words, it is the particle that does not go through the cavity that gives up its energy! If this analysis is correct, this behaviour would be truly bizarre and could only be explained by an extreme non-local transfer of energy that is even stronger than that required in an Einstein, Podolsky and Rosen (EPR)-type process. In this paper, we show that this conclusion is not correct and that if the BI is used correctly, it gives a local explanation, which actually corresponds exactly to the standard quantum mechanics explanation offered by ESSW.
TL;DR: In this article, the effect of the vertical magnetic field and modulation of the walls' temperature was investigated using Floquet theory, and it was found that the magnetic field has a stabilizing influence on the onset of thermal instability.
Abstract: Convective instability in a horizontal layer of electrically conducting fluid, heated from below, is investigated in the presence of an applied vertical magnetic field. The temperature gradient between the walls of the fluid layer consists of a steady part and a time dependent oscillatory part. The temperature of both walls is modulated. The combined effect of the vertical magnetic field and modulation of walls' temperature is investigated using Floquet theory. It is found that the effect of magnetic field has a stabilizing influence on the onset of thermal instability. Further, it is also found that it is possible to advance or delay the onset of convection by proper tuning of the frequency of modulation of the walls' temperature.
TL;DR: In this article, the authors present new predictions for the chemical sputtering of carbon by atomic hydrogen and different ions relevant to plasma-wall interaction in nuclear fusion devices (He+, H+, D+, T+ and Ne+) and new experimental data for the Chemical sputtering due to hydrogen and Ne+ ions.
Abstract: Simultaneous interaction of low-energy ions and atomic hydrogen—a process named chemical sputtering—causes erosion of C:H surfaces which is significantly higher than the sum of the individual processes—chemical erosion due to atomic hydrogen alone and physical sputtering due to ions. Above that, this process occurs also at energies below the threshold for physical sputtering. A microscopic reaction mechanism for chemical sputtering was recently suggested. A mathematical model based on this reaction mechanism is able to quantitatively reproduce the energy dependence of chemical sputtering by atomic hydrogen and argon using just one free parameter. The model is briefly reviewed and the underlying physical processes are discussed. We present new predictions for the chemical sputtering of carbon by atomic hydrogen and different ions relevant to plasma–wall interaction in nuclear fusion devices (He+, H+, D+, T+ and Ne+) and new experimental data for the chemical sputtering due to hydrogen and Ne+ ions.
TL;DR: In this article, the authors developed a framework for implementing a scaled selfinteraction corrected density functional theory (DFT-SIC) into pseudo-potential plane-wave DFT.
Abstract: We recently developed a framework for implementing a scaled self-interaction corrected density functional theory (DFT-SIC) into pseudo-potential plane-wave DFT. The technique implements the original method of Perdew and Zunger by direct minimization of the DFT-SIC total energy functional. By using maximally localized Wannier functions, DFT-SIC calculation can be carried out efficiently even for extended systems. Using this new development, the formation energies of defects in 3C–SiC (silicon carbide) were calculated and compared to more standard DFT calculations. Differences of up to 1 eV were seen between DFT and DFT-SIC calculations of the formation energies. When compared to DFT, DFT-SIC produced less-stable vacancies and silicon interstitials, and more stable antisites and carbon interstitials. The most favourable interstitials were found to be C interstitials in a C+–C100 dumbbell configuration, with the formation energy of 5.91 eV with DFT and 5.65 eV with DFT-SIC. Si interstitials were not as stable as C interstitials. The most favourable Si interstitial was found to be Si tetrahedral surrounded by four C atoms, with a formation energy of 7.65 eV with DFT and 8.71 eV with DFT-SIC.
TL;DR: In this paper, the electron levels of odd parity in neutral praseodymium were found on the basis of an analysis of hitherto unclassified spectral lines with the method of laser-induced fluorescence (LIF).
Abstract: Fifty seven new electron levels of odd parity in neutral praseodymium are presented. These have been found on the basis of an analysis of hitherto unclassified spectral lines with the method of laser-induced fluorescence (LIF). For all the levels the hyperfine magnetic dipole interaction constants A have been determined.
TL;DR: Tritium retention by codeposition with carbon on the divertor target plate is predicted to limit ITER's DT burning plasma operations (e.g. to about 100 pulses for the worst conditions) before the in-vessel tritium inventory limit, currently set at ~350?g, is reached.
Abstract: Tritium retention by codeposition with carbon on the divertor target plate is predicted to limit ITER's DT burning plasma operations (e.g. to about 100 pulses for the worst conditions) before the in-vessel tritium inventory limit, currently set at ~350?g, is reached. At this point, ITER will only be able to continue its burning plasma program if technology is available that is capable of rapidly removing large quantities of tritium from the vessel with over 90% efficiency. The removal rate required is four orders of magnitude faster than that demonstrated in current tokamaks. 18 years after the observation of co-deposition on JET and TFTR, such technology is nowhere in sight. The inexorable conclusion is that either a major initiative in tritium removal should be funded or that research priorities for ITER should focus on metal alternatives at least for DT operations.
TL;DR: X-ray diffraction patterns of NiPc in powder form show that it has a?-form with monoclinic structure, while the conversion into?-NiPc is completed at 623?K as discussed by the authors.
Abstract: X-ray diffraction patterns of NiPc in powder form show that it has a ?-form with monoclinic structure. The thermal evaporation of NiPc led to ?-polycrystalline films orientated preferentially to the (001) plane with an amorphous background. After annealing at 573?K for 2?h, a mixture of ?- and ?-phases was formed, while the conversion into ?-NiPc is completed at 623?K. The dark electrical resistivity has been measured on NiPc films in the temperature range 298?423?K. Two activation energies ?E1 = 0.12?eV and ?E2 = 0.76?eV were obtained. The thermal activation energy ?E1 is associated with impurity conduction and ?E2 is associated with intrinsic conduction. Thermoelectric power measurement proved that NiPc films are p-type. The thermoelectric power curves also exhibit two different regions corresponding to extrinsic and intrinsic conductions. Room temperature J?V measurements show a linear ohmic dependence at low voltages, followed by SCLC at higher voltage levels, dominated by an exponential distribution of traps with total trap concentration of 2.79 ? 1022?m?3.