WorldWideScience

Sample records for ion transport phenomena

  1. Transport phenomena

    International Nuclear Information System (INIS)

    Kirczenow, G.; Marro, J.

    1974-01-01

    Some simple remarks on the basis of transport theory. - Entropy, dynamics and scattering theory. - Response, relaxation and fluctuation. - Fluctuating hydrodynamics and renormalization of susceptibilities and transport coefficients. - Irreversibility of the transport equations. - Ergodic theory and statistical mechanics. - Correlation functions in Heisenberg magnets. - On the Enskog hard-sphere kinetic eqquation and the transport phenomena of dense simple gases. - What can one learn from Lorentz models. - Conductivity in a magnetic field. - Transport properties in gases in presence of external fields. - Transport properties of dilute gases with internal structure. (orig.) [de

  2. Barodiffusion phenomena at active transport of na+ and K+ ions through the cell membrane

    International Nuclear Information System (INIS)

    Khrapijchuk, G.V.; Chalyi, A.V.; Nurishchenko, N.Je.

    2010-01-01

    The influence of ultrasound as the significant motive force of barodiffusion phenomena at the processes of active transport of Na + and K + ions through the cell membrane is considered. The dependence of membrane potential is theoretically estimated at active transport of natrium and potassium ions on the ultrasound intensity and pressure overfall between external and internal medium of the cell.

  3. Ion exchange phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Bourg, I.C.; Sposito, G.

    2011-05-01

    Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

  4. Fast-ion transport during repetitive burst phenomena of toroidal Alfven eigenmodes in the Large Helical Device

    International Nuclear Information System (INIS)

    Nishiura, M.; Isobe, M.; Yamamoto, S.

    2008-10-01

    Alfven instabilities induced fast-ion losses have been directly observed for the first time by a newly developed scintillator lost ion probe (SLIP) in the Large Helical Device (LHD). The SLIP can measure the pitch angle and gyro radius of escaped fast ions toward loss region. Neutral beam driven Alfven Eigenmodes (AEs) are excited under the reactor relevant conditions: the ratio of fast ion (beam) speed υ b and Alfven speed υ A is more than 0.3 - 4.0. The beta value for fast ions is considered roughly to be ∼10%. Non-linear phenomena related to Alfven instabilities are observed under such conditions. During repetitive Toroidal Alfven Eigenmode (TAE) bursts, synchronized fast ion losses are observed by SLIP. From the orbit calculation the measured fast ion with pitch angle of 130 degrees and beam energy of 150 keV surely pass through the locations of TAE gaps. The orbit analysis found that the observed fast ions interact strongly with the excited TAEs. This result becomes the first experimental evidence of radial transport of fast ions predicted theoretically during TAE activities. In addition, from the correlation between stored energy degradation and fast-ion loss rate, it is found that fast-ion losses induced by TAE activities with low toroidal mode numbers categorize two phenomena without and with fast- ion loss enhancements, which indicate the fast-ion redistribution and loss. (author)

  5. Interfacial transport phenomena

    CERN Document Server

    Slattery, John C; Oh, Eun-Suok

    2007-01-01

    Revised and updated extensively from the previous editionDiscusses transport phenomena at common lines or three-phase lines of contactProvides a comprehensive summary about the extensions of continuum mechanics to the nanoscale.

  6. Modelling of transport phenomena

    International Nuclear Information System (INIS)

    Itoh, Kimitaka; Itoh, Sanae; Fukuyama, Atsushi.

    1993-09-01

    In this review article, we discuss key features of the transport phenomena and theoretical modelling to understand them. Experimental observations have revealed the nature of anomalous transport, i.e., the enhancement of the transport coefficients by the gradients of the plasma profiles, the pinch phenomena, the radial profile of the anomalous transport coefficients, the variation of the transport among the Bohm diffusion, Pseudo-classical confinement, L-mode and variety of improved confinement modes, and the sudden jumps such as L-H transition. Starting from the formalism of the transport matrix, the modelling based on the low frequency instabilities are reviewed. Theoretical results in the range of drift wave frequency are examined. Problems in theories based on the quasilinear and mixing-length estimates lead to the renewal of the turbulence theory, and the physics picture of the self-sustained turbulence is discussed. The theory of transport using the fluid equation of plasma is developed, showing that the new approach is very promising in explaining abovementioned characteristics of anomalous transport in both L-mode and improved confinement plasmas. The interference of the fluxes is the key to construct the physics basis of the bifurcation theory for the L-H transition. The present status of theories on the mechanisms of improved confinement is discussed. Modelling on the nonlocal nature of transport is briefly discussed. Finally, the impact of the anomalous transport on disruptive phenomena is also described. (author) 95 refs

  7. Relaxation phenomena in and microscopic transport theories of deeply inelastic collisions between heavy ions

    International Nuclear Information System (INIS)

    Noerenberg, W.

    1976-01-01

    Relaxation phenomena in deeply inelastic collisions are qualitatively discussed and compared with precompound reactions. Different approaches for describing these processes are reviewed, in particular the microscopic transport theories, which can be understood from a generalized master equation for macroscopic variables. The Markoff approximation and the classical limit for the relative motion lead to two coupled equations, the classical equation of relative motion with friction and a Pauli master equation for the internal degrees of freedom. The master equation approximated by the corresponding Fokker-Planck equation for mass transfer and energy dissipation is discussed in detail. Simple analytic expressions are derived for the transport coefficients as functions of excitation energy, total mass, mass fragmentation and relative angular momentum. Calculated transport coefficients are compared with experimental values. Problems and future developments in microscopic transport theories are outlined. (orig.) [de

  8. Transport phenomena II essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena II covers forced convention, temperature distribution, free convection, diffusitivity and the mechanism of mass transfer, convective mass transfer, concentration

  9. Transport phenomena I essentials

    CERN Document Server

    REA, The Editors of

    2012-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Transport Phenomena I includes viscosity, flow of Newtonian fluids, velocity distribution in laminar flow, velocity distributions with more than one independent variable, thermal con

  10. Transport phenomena in environmental engineering

    Science.gov (United States)

    Sander, Aleksandra; Kardum, Jasna Prlić; Matijašić, Gordana; Žižek, Krunoslav

    2018-01-01

    A term transport phenomena arises as a second paradigm at the end of 1950s with high awareness that there was a strong need to improve the scoping of chemical engineering science. At that point, engineers became highly aware that it is extremely important to take step forward from pure empirical description and the concept of unit operations only to understand the specific process using phenomenological equations that rely on three elementary physical processes: momentum, energy and mass transport. This conceptual evolution of chemical engineering was first presented with a well-known book of R. Byron Bird, Warren E. Stewart and Edwin N. Lightfoot, Transport Phenomena, published in 1960 [1]. What transport phenomena are included in environmental engineering? It is hard to divide those phenomena through different engineering disciplines. The core is the same but the focus changes. Intention of the authors here is to present the transport phenomena that are omnipresent in treatment of various process streams. The focus in this chapter is made on the transport phenomena that permanently occur in mechanical macroprocesses of sedimentation and filtration for separation in solid-liquid particulate systems and on the phenomena of the flow through a fixed and a fluidized bed of particles that are immanent in separation processes in packed columns and in environmental catalysis. The fundamental phenomena for each thermal and equilibrium separation process technology are presented as well. Understanding and mathematical description of underlying transport phenomena result in scoping the separation processes in a way that ChEs should act worldwide.

  11. Transport phenomena in dissipative heavy-ion collisions: the one-body dissipation approach

    International Nuclear Information System (INIS)

    Feldmeier, H.

    1987-01-01

    The paper reviews dissipative collisions between two atomic nuclei, with the help of the classical description of Brownian movement and the Langevin equation. The 'one-body dissipation model' for dissipative heavy-ion collisions is discussed, and its predictions are compared with measured data. Special attention is paid to the non-equilibrium relation between friction and diffusion. (U.K.)

  12. Micro transport phenomena during boiling

    CERN Document Server

    Peng, Xiaofeng

    2011-01-01

    "Micro Transport Phenomena During Boiling" reviews the new achievements and contributions in recent investigations at microscale. It presents some original research results and discusses topics at the frontier of thermal and fluid sciences.

  13. Transport Phenomena in Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2016-05-01

    Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

  14. Lunar magma transport phenomena

    Science.gov (United States)

    Spera, Frank J.

    1992-01-01

    An outline of magma transport theory relevant to the evolution of a possible Lunar Magma Ocean and the origin and transport history of the later phase of mare basaltic volcanism is presented. A simple model is proposed to evaluate the extent of fractionation as magma traverses the cold lunar lithosphere. If Apollo green glasses are primitive and have not undergone significant fractionation en route to the surface, then mean ascent rates of 10 m/s and cracks of widths greater than 40 m are indicated. Lunar tephra and vesiculated basalts suggest that a volatile component plays a role in eruption dynamics. The predominant vapor species appear to be CO CO2, and COS. Near the lunar surface, the vapor fraction expands enormously and vapor internal energy is converted to mixture kinetic energy with the concomitant high-speed ejection of vapor and pyroclasts to form lunary fire fountain deposits such as the Apollo 17 orange and black glasses and Apollo 15 green glass.

  15. Transport phenomena in multiphase flows

    CERN Document Server

    Mauri, Roberto

    2015-01-01

    This textbook provides a thorough presentation of the phenomena related to the transport of mass, momentum and energy.  It lays all the basic physical principles, then for the more advanced readers, it offers an in-depth treatment with advanced mathematical derivations and ends with some useful applications of the models and equations in specific settings. The important idea behind the book is to unify all types of transport phenomena, describing them within a common framework in terms of cause and effect, respectively represented by the driving force and the flux of the transported quantity. The approach and presentation are original in that the book starts with a general description of transport processes, providing the macroscopic balance relations of fluid dynamics and heat and mass transfer, before diving into the mathematical realm of continuum mechanics to derive the microscopic governing equations at the microscopic level. The book is a modular teaching tool and can be used either for an introductory...

  16. Transport phenomena in particulate systems

    CERN Document Server

    Freire, José Teixeira; Ferreira, Maria do Carmo

    2012-01-01

    This volume spans 10 chapters covering different aspects of transport phenomena including fixed and fluidized systems, spouted beds, electrochemical and wastewater treatment reactors. This e-book will be valuable for students, engineers and researchers aiming to keep updated on the latest developments on particulate systems.

  17. Gravitational Anomaly and Transport Phenomena

    International Nuclear Information System (INIS)

    Landsteiner, Karl; Megias, Eugenio; Pena-Benitez, Francisco

    2011-01-01

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid.

  18. Polarization phenomena in heavy-ion reactions

    International Nuclear Information System (INIS)

    Sugimoto, K.; Ishihara, M.; Takahashi, N.

    1984-01-01

    This chapter presents a few key experiments which provide direct evidence of the polarization phenomena in heavy-ion reactions. The theory of polarization observables and measurements is given with the necessary formulae. The polarization phenomena is described and studies of product nuclear polarization in heavy-ion reactions are discussed. Studies of heavy-ion reactions induced by polarized beams are examined

  19. Transport phenomena in porous media

    CERN Document Server

    Ingham, Derek B

    1998-01-01

    Research into thermal convection in porous media has substantially increased during recent years due to its numerous practical applications. These problems have attracted the attention of industrialists, engineers and scientists from many very diversified disciplines, such as applied mathematics, chemical, civil, environmental, mechanical and nuclear engineering, geothermal physics and food science. Thus, there is a wealth of information now available on convective processes in porous media and it is therefore appropriate and timely to undertake a new critical evaluation of this contemporary information. Transport Phenomena in Porous Media contains 17 chapters and represents the collective work of 27 of the world's leading experts, from 12 countries, in heat transfer in porous media. The recent intensive research in this area has substantially raised the expectations for numerous new practical applications and this makes the book a most timely addition to the existing literature. It includes recent major deve...

  20. Transport phenomena an introduction to advanced topics

    CERN Document Server

    Glasgow, Larry A

    2010-01-01

    Enables readers to apply transport phenomena principles to solve advanced problems in all areas of engineering and science This book helps readers elevate their understanding of, and their ability to apply, transport phenomena by introducing a broad range of advanced topics as well as analytical and numerical solution techniques. Readers gain the ability to solve complex problems generally not addressed in undergraduate-level courses, including nonlinear, multidimensional transport, and transient molecular and convective transport scenarios. Avoiding rote memorization, the author em

  1. A Connection between Transport Phenomena and Thermodynamics

    Science.gov (United States)

    Swaney, Ross; Bird, R. Byron

    2017-01-01

    Although students take courses in transport phenomena and thermodynamics, they probably do not ask whether these two subjects are related. Here we give an answer to that question. Specifically we give relationships between the equations of change for total energy, internal energy, and entropy of transport phenomena and key equations of equilibrium…

  2. Phenomena of charged particles transport in variable magnetic fields

    International Nuclear Information System (INIS)

    Savane, Sy Y.; Faza Barry, M.; Vladmir, L.; Diaby, I.

    2002-11-01

    This present work is dedicated to the study of the dynamical phenomena for the transport of ions in the presence of variable magnetic fields in front of the Jupiter wave shock. We obtain the spectrum of the accelerated ions and we study the conditions of acceleration by solving the transport equation in the planetocentric system. We discuss the theoretical results obtained and make a comparison with the experimental parameters in the region of acceleration behind the Jupiter wave shock. (author)

  3. Computational transport phenomena for engineering analyses

    CERN Document Server

    Farmer, Richard C; Cheng, Gary C; Chen, Yen-Sen

    2009-01-01

    Computational Transport PhenomenaOverviewTransport PhenomenaAnalyzing Transport PhenomenaA Computational Tool: The CTP CodeVerification, Validation, and GeneralizationSummaryNomenclatureReferencesThe Equations of ChangeIntroductionDerivation of The Continuity EquationDerivation of The Species Continuity EquationDerivation of The Equation Of MotionDerivation of The General Energy EquationNon-Newtonian FluidsGeneral Property BalanceAnalytical and Approximate Solutions for the Equations of ChangeSummaryNomenclatureReferencesPhysical PropertiesOverviewReal-Fluid ThermodynamicsChemical Equilibrium

  4. Kinetic theory and transport phenomena

    CERN Document Server

    Soto, Rodrigo

    2016-01-01

    This textbook presents kinetic theory, which is a systematic approach to describing nonequilibrium systems. The text is balanced between the fundamental concepts of kinetic theory (irreversibility, transport processes, separation of time scales, conservations, coarse graining, distribution functions, etc.) and the results and predictions of the theory, where the relevant properties of different systems are computed. The book is organised in thematic chapters where different paradigmatic systems are studied. The specific features of these systems are described, building and analysing the appropriate kinetic equations. Specifically, the book considers the classical transport of charges, the dynamics of classical gases, Brownian motion, plasmas, and self-gravitating systems, quantum gases, the electronic transport in solids and, finally, semiconductors. Besides these systems that are studied in detail, concepts are applied to some modern examples including the quark–gluon plasma, the motion of bacterial suspen...

  5. Advances in transport phenomena 2011

    CERN Document Server

    2014-01-01

    This new volume of the annual review “Advances in Transport Phenomena” series contains three in-depth review articles on the microfluidic fabrication of vesicles, the dielectrophoresis field-flow fractionation for continuous-flow separation of particles and cells in microfluidic devices, and the thermodynamic analysis and optimization of heat exchangers, respectively.

  6. Transport phenomena in strongly correlated Fermi liquids

    International Nuclear Information System (INIS)

    Kontani, Hiroshi

    2013-01-01

    Comprehensive overview. Written by an expert of this topic. Provides the reader with current developments in the field. In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, τ, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical point using a uniform approach. We also discuss spin related transport phenomena in strongly correlated systems. In many d- and f-electron systems, the spin current induced by the spin Hall effect is considerably greater because of the orbital degrees of freedom. This fact attracts much attention due to its potential application in spintronics. We discuss various novel charge, spin and heat transport phenomena in strongly correlated metals.

  7. Transport phenomena in strongly correlated Fermi liquids

    CERN Document Server

    Kontani, Hiroshi

    2013-01-01

    In conventional metals, various transport coefficients are scaled according to the quasiparticle relaxation time, \\tau, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems, reflecting their unique electronic states. The most famous example would be cuprate high-Tc superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. To better understand the origin of this discrepancy, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. Near the magnetic quantum critical point, the current vertex correction (CVC), which describes the electron-electron scattering beyond the relaxation time approximation, gives rise to various anomalous transport phenomena. We explain anomalous transport phenomena in cuprate HTSCs and other metals near their magnetic or orbital quantum critical poi...

  8. Basic transport phenomena in materials engineering

    CERN Document Server

    Iguchi, Manabu

    2014-01-01

    This book presents the basic theory and experimental techniques of transport phenomena in materials processing operations. Such fundamental knowledge is highly useful for researchers and engineers in the field to improve the efficiency of conventional processes or develop novel technology. Divided into four parts, the book comprises 11 chapters describing the principles of momentum transfer, heat transfer, and mass transfer in single phase and multiphase systems. Each chapter includes examples with solutions and exercises to facilitate students’ learning. Diagnostic problems are also provided at the end of each part to assess students’ comprehension of the material.  The book is aimed primarily at students in materials science and engineering. However, it can also serve as a useful reference text in chemical engineering as well as an introductory transport phenomena text in mechanical engineering. In addition, researchers and engineers engaged in materials processing operations will find the material use...

  9. Thermal transport phenomena in nanoparticle suspensions

    International Nuclear Information System (INIS)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-01-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications. (topical review)

  10. Individual and collective motions: transport phenomena

    International Nuclear Information System (INIS)

    Richert, J.

    The present lectures deal with the description of deep inelastic heavy ion reaction mechanism by means of transport concepts which were developed in statistical mechanics. The applicability of those concepts is analysed in terms of a hierarchy of characteristic times. The specificity of this time scale in the heavy ion framework is underlined. The derivation of transport coefficients out of the full dynamical formulation of the problem is shown through a random matrix model. The mechanism of mass and charge transfer between the ions as well as the generation of intrinsic angular momenta in the interacting fragments is formulated, quantitatively worked out and compared to some experimental results by using phenomenological approaches. Weak points of the theoretical approaches and disagreement between phenomenological models and experimental data are discussed. Open problems and unsolved questions are sketched in the final conclusions [fr

  11. Modeling in transport phenomena a conceptual approach

    CERN Document Server

    Tosun, Ismail

    2007-01-01

    Modeling in Transport Phenomena, Second Edition presents and clearly explains with example problems the basic concepts and their applications to fluid flow, heat transfer, mass transfer, chemical reaction engineering and thermodynamics. A balanced approach is presented between analysis and synthesis, students will understand how to use the solution in engineering analysis. Systematic derivations of the equations and the physical significance of each term are given in detail, for students to easily understand and follow up the material. There is a strong incentive in science and engineering to

  12. Ion rarefaction waves and associated phenomena

    International Nuclear Information System (INIS)

    Coates, A.J.

    1982-01-01

    This thesis contains an experimental and theoretical study of the response of a plasma to the motion of the positive space-charge sheath which bounds it . It is known theoretically that, if a sheath edge is moved at a speed less than the speed of ion acoustic waves, a region of ion rarefaction propagates into the plasma at the ion acoustic speed. Some calculations are described which include the effects of an initial presheath by constructing a one-dimensional plasma solution where a production term balances the losses of ions to the walls. The plasma response to the motion of one boundary is found using the method of characteristics with appropriate boundary conditions. Ion rarefaction waves are associated with expanding sheaths while ion 'enhancement' waves (compressive features) are formed on sheath collapse. In each case the wavefront moves at the local ion acoustic speed which includes the effects of ion drift. The presence of the presheath is essential to the generation of enhancements. The constructional details of a multidipole device are discussed, and the results of Langmuir probe and ion acoustic wave experiments are used to determine the parameters of a quiescent argon plasma. Some experiments on moving sheaths in such a plasma are then considered. (author)

  13. Ion transport in stellarators

    International Nuclear Information System (INIS)

    Ho, D.D.M.; Kulsrud, R.M.

    1985-09-01

    Stellarator ion transport in the low-collisionality regime with a radial electric field is calculated by a systematic expansion of the drift-Boltzmann equation. The shape of the helical well is taken into account in this calculation. It is found that the barely trapped ions with three to four times the thermal energy give the dominant contribution to the diffusion. Expressions for the ion particle and energy fluxes are derived

  14. Electron impact phenomena and the properties of gaseous ions

    CERN Document Server

    Field, F H; Massey, H S W; Brueckner, Keith A

    1970-01-01

    Electron Impact Phenomena and the Properties of Gaseous Ions, Revised Edition deals with data pertaining to electron impact and to molecular gaseous ionic phenomena. This book discusses electron impact phenomena in gases at low pressure that involve low-energy electrons, which result in ion formation. The text also describes the use of mass spectrometers in electron impact studies and the degree of accuracy obtained when measuring electron impact energies. This book also reviews relatively low speed electrons and the transitions that result in the ionization of the atomic system. This text the

  15. Exotic phenomena in collisions of heavy ions

    International Nuclear Information System (INIS)

    Soff, G.; Schramm, S.; Reus, T. de; Mehler, G.; Reinhardt, J.; Mueller, B.; Greiner, W.; Mueller, U.

    1985-08-01

    To exemplify current theoretical investigations we discuss three different topics. After a presentation of the underlying theoretical framework for ionization processes we will sketch the possibility to employ delta-electron emission as a clock to measure nuclear reaction times in intermediate energy collisions of very heavy ions. Besides the phenomenon of vacuum decay into a new twofold negatively charged stable vacuum ground state, electron excitation in heavy ion collisions may be employed for the determination of delay and deceleration times on the nuclear time scale, i.e. offering an atomic clock, operating in the range 10 -21 -10 -24 s. In deep-inelastic heavy ion collisions this provides a test for classical nuclear reaction models. In collisions at intermediate energies an independent measurement of the deceleration time is of interest for comparison, e.g., with the results of the pion bremsstrahlung model. After that we investigate the influence of one or more pockets in the ion scattering potential on the energy distribution of emitted positrons within a quantum mechanical framework. Finally we very briefly consider some phenomenological corrections to the Dirac equation and its consequences on electron binding energies in heavy and superheavy atoms. (orig./HSI)

  16. Collective phenomena in negative ion photodetachment

    International Nuclear Information System (INIS)

    Ivanov, V.K.

    1996-01-01

    The many-electron collective effects in negative ion photodetachment are discussed. The calculations of photodetachment cross sections and photoelectron angular distributions have been performed within the Many-Body Theory Methods. It is shown that the role of many-electron interactions leading to the collective effects like dynamical polarizability, interchannel interaction, core polarization, core relaxation, is very important to describe the photodetachment processes. (author)

  17. Coupled Mechanical and Electrochemical Phenomena in Lithium-Ion Batteries

    Science.gov (United States)

    Cannarella, John

    Lithium-ion batteries are complee electro-chemo-mechanical systems owing to a number of coupled mechanical and electrochemical phenomena that occur during operation. In this thesis we explore these phenomena in the context of battery degradation, monitoring/diagnostics, and their application to novel energy systems. We begin by establishing the importance of bulk stress in lithium-ion batteries through the presentation of a two-year exploratory aging study which shows that bulk mechanical stress can significantly accelerate capacity fade. We then investigate the origins of this coupling between stress and performance by investigating the effects of stress in idealized systems. Mechanical stress is found to increase internal battery resistance through separator deformation, which we model by considering how deformation affects certain transport properties. When this deformation occurs in a spatially heterogeneous manner, local hot spots form, which accelerate aging and in some cases lead to local lithium plating. Because of the importance of separator deformation with respect to mechanically-coupled aging, we characterize the mechanical properties of battery separators in detail. We also demonstrate that the stress state of a lithium-ion battery cell can be used to measure the cell's state of health (SOH) and state of charge (SOC)--important operating parameters that are traditionally difficult to measure outside of a laboratory setting. The SOH is shown to be related to irreversible expansion that occurs with degradation and the SOC to the reversible strains characteristic of the cell's electrode materials. The expansion characteristics and mechanical properties of the constituent cell materials are characterized, and a phenomenological model for the relationship between stress and SOH/SOC is developed. This work forms the basis for the development of on-board monitoring of SOH/SOC based on mechanical measurements. Finally we study the coupling between mechanical

  18. Range shortening, radiation transport, and Rayleigh-Taylor instability phenomena in ion-beam-driven inertial-fusion-reactor-size targets: Implosion, ignition, and burn phases

    International Nuclear Information System (INIS)

    Long, K.A.; Tahir, N.A.

    1987-01-01

    In this paper we present an analysis of the theory of the energy deposition of ions in cold materials and hot dense plasmas together with numerical calculations for heavy and light ions of interest to ion-beam fusion. We have used the gorgon computer code of Long, Moritz, and Tahir (which is an extension of the code originally written for protons by Nardi, Peleg, and Zinamon) to carry out these calculations. The energy-deposition data calculated in this manner has been used in the design of heavy-ion-beam-driven fusion targets suitable for a reactor, by its inclusion in the medusa code of Christiansen, Ashby, and Roberts as extended by Tahir and Long. A number of other improvements have been made in this code and these are also discussed. Various aspects of the theoretical analysis of such targets are discussed including the calculation of the hydrodynamic stability, the hydrodynamic efficiency, and the gain. Various different target designs have been used, some of them new. In general these targets are driven by Bi + ions of energy 8--12 GeV, with an input energy of 4--6.5 MJ, with output energies in the range 600--900 MJ, and with gains in the range 120--180. The peak powers are in the range of 500--750 TW. We present detailed calculations of the ablation, compression, ignition, and burn phases. By the application of a new stability analysis which includes ablation and density-gradient effects we show that these targets appear to implode in a stable manner. Thus the targets designed offer working examples suited for use in a future inertial-confinement fusion reactor

  19. Transport phenomena in materials processing---1990

    International Nuclear Information System (INIS)

    Bishop, B.J.; Lior, N.; Lavine, A.; Flik, M.; Karwe, M.V.; Bergman, T.L.; Beckermann, C.; Charmchi, M.

    1990-01-01

    The papers contained in this volume represent a wide range of current research interests in processes such as food and polymer processing, casting, welding, machining, laser cutting, and superconductor processing. This volume includes papers presented in four sessions: Heat Transfer in Materials Processing; Thermal Phenomena in Superconductor Processing; Heat Transfer in Food and Polymer Processing; Heat Transfer in CAsting and Welding

  20. Transport phenomena in Newtonian fluids a concise primer

    CERN Document Server

    Olsson, Per

    2013-01-01

    This short primer provides a concise and tutorial-style introduction to transport phenomena in Newtonian fluids , in particular the transport of mass, energy and momentum.  The reader will find detailed derivations of the transport equations for these phenomena, as well as selected analytical solutions to the transport equations in some simple geometries. After a brief introduction to the basic mathematics used in the text, Chapter 2, which deals with momentum transport, presents a derivation of the Navier-Stokes-Duhem equation describing the basic flow in a Newtonian fluid.  Also provided at

  1. Monte Carlo simulation of neutron transport phenomena

    International Nuclear Information System (INIS)

    Srinivasan, P.

    2009-01-01

    Neutron transport is one of the central problems in nuclear reactor related studies and other applied sciences. Some of the major applications of neutron transport include nuclear reactor design and safety, criticality safety of fissile material handling, neutron detector design and development, nuclear medicine, assessment of radiation damage to materials, nuclear well logging, forensic analysis etc. Most reactor and dosimetry studies assume that neutrons diffuse from regions of high to low density just like gaseous molecules diffuse to regions of low concentration or heat flow from high to low temperature regions. However while treatment of gaseous or heat diffusion is quite accurately modeled, treatment of neutron transport as simple diffusion is quite limited. In simple diffusion, the neutron trajectories are irregular, random and zigzag - where as in neutron transport low reaction cross sections (1 barn- 10 -24 cm 2 ) lead to long mean free paths which again depend on the nature and irregularities of the medium. Hence a more accurate representation of the neutron transport evolved based on the Boltzmann equation of kinetic gas theory. In fact the neutron transport equation is a linearized version of the Boltzmann gas equation based on neutron conservation with seven independent variables. The transport equation is difficult to solve except in simple cases amenable to numerical methods. The diffusion (equation) approximation follows from removing the angular dependence of the neutron flux

  2. Phenomena in thermal transport in fuels

    International Nuclear Information System (INIS)

    Chernatynskiy, A.; Tulenko, J.S.; Phillpot, S.R.; El-Azab, A.

    2015-01-01

    Thermal transport in nuclear fuels is a key performance metric that affects not only the power output, but is also an important consideration in potential accident situations. While the fundamental theory of the thermal transport in crystalline solids was extensively developed in the 1950's and 1960's, the pertinent analytic approaches contained significant simplifications of the physical processes. While these approaches enabled estimates of the thermal conductivity in bulk materials with microstructure, they were not comprehensive enough to provide the detailed guidance needed for the in-pile fuel performance. Rather, this guidance has come from data painfully accumulated over 50 years of experiments on irradiated uranium dioxide, the most widely used nuclear fuel. At this point, a fundamental theoretical understanding of the interplay between the microstructure and thermal conductivity of irradiated uranium dioxide fuel is still lacking. In this chapter, recent advances are summarised in the modelling approaches for thermal transport of uranium dioxide fuel. Being computational in nature, these modelling approaches can, at least in principle, describe in detail virtually all mechanisms affecting thermal transport at the atomistic level, while permitting the coupling of the atomistic-level simulations to the mesoscale continuum theory and thus enable the capture of the impact of microstructural evolution in fuel on thermal transport. While the subject of current studies is uranium dioxide, potential applications of the methods described in this chapter extend to the thermal performance of other fuel forms. (authors)

  3. PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media

    Science.gov (United States)

    Eikerling, Michael

    2011-06-01

    Proton transport phenomena are of paramount importance for acid-base chemistry, energy transduction in biological organisms, corrosion processes, and energy conversion in electrochemical systems such as polymer electrolyte fuel cells. The relevance for such a plethora of materials and systems, and the ever-lasting fascination with the highly concerted nature of underlying processes drive research across disciplines in chemistry, biology, physics and chemical engineering. A proton never travels alone. Proton motion is strongly correlated with its environment, usually comprised of an electrolyte and a solid or soft host material. For the transport in nature's most benign proton solvent and shuttle, water that is, insights from ab initio simulations, matured over the last 15 years, have furnished molecular details of the structural diffusion mechanism of protons. Excess proton movement in water consists of sequences of Eigen-Zundel-Eigen transitions, triggered by hydrogen bond breaking and making in the surrounding water network. Nowadays, there is little debate about the validity of this mechanism in water, which bears a stunning resemblance to the basic mechanistic picture put forward by de Grotthuss in 1806. While strong coupling of an excess proton with degrees of freedom of solvent and host materials facilitates proton motion, this coupling also creates negative synergies. In general, proton mobility in biomaterials and electrochemical proton conducting media is highly sensitive to the abundance and structure of the proton solvent. In polymer electrolyte membranes, in which protons are bound to move in nano-sized water-channels, evaporation of water or local membrane dehydration due to electro-osmotic coupling are well-known phenomena that could dramatically diminish proton conductivity. Contributions in this special issue address various vital aspects of the concerted nature of proton motion and they elucidate important structural and dynamic effects of solvent

  4. Imaging unsteady three-dimensional transport phenomena

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... The image data can be jointly analysed with the physical laws governing transport and principles of image formation. Hence, with the experiment suitably carried out, three-dimensional physical domains with unsteady processes can be accommodated. Optical methods promise to breach the holy grail of ...

  5. Charge Transport Phenomena in Peptide Molecular Junctions

    International Nuclear Information System (INIS)

    Luchini, A.; Petricoin, E.F.; Geho, D.H.; Liotta, L.A.; Long, D.P.; Vaisman, I.I.

    2008-01-01

    Inelastic electron tunneling spectroscopy (IETS) is a valuable in situ spectroscopic analysis technique that provides a direct portrait of the electron transport properties of a molecular species. In the past, IETS has been applied to small molecules. Using self-assembled nano electronic junctions, IETS was performed for the first time on a large polypeptide protein peptide in the phosphorylated and native form, yielding interpretable spectra. A reproducible 10-fold shift of the I/V characteristics of the peptide was observed upon phosphorylation. Phosphorylation can be utilized as a site-specific modification to alter peptide structure and thereby influence electron transport in peptide molecular junctions. It is envisioned that kinases and phosphatases may be used to create tunable systems for molecular electronics applications, such as biosensors and memory devices.

  6. Coupled electric and transport phenomena in porous media

    NARCIS (Netherlands)

    Li, Shuai

    2014-01-01

    The coupled electrical and transport properties of clay-containing porous media are the topics of interest in this study. Both experimental and numerical (pore network modeling) techniques are employed to gain insight into the macro-scale interaction between electrical and solute transport phenomena

  7. Metal ion transporters and homeostasis.

    OpenAIRE

    Nelson, N

    1999-01-01

    Transition metals are essential for many metabolic processes and their homeostasis is crucial for life. Aberrations in the cellular metal ion concentrations may lead to cell death and severe diseases. Metal ion transporters play a major role in maintaining the correct concentrations of the various metal ions in the different cellular compartments. Recent studies of yeast mutants revealed key elements in metal ion homeostasis, including novel transport systems. Several of the proteins discover...

  8. Many-electron phenomena in the ionization of ions

    International Nuclear Information System (INIS)

    Mueller, A.

    2004-01-01

    Full text: Single and multiple ionization in ion-atom collisions involve a multitude of complex interactions between the electrons and nuclei of projectile and target. Some of the complexity is avoided in studies of fast collisions when the impulse approximation can be applied and the electrons can be described as independent quasi-free particles with a known momentum distribution. For the detailed investigation of ionization mechanisms that can occur in fast ion-atom collisions, it is illuminating to consider collisions of ions (or atoms) and really free electrons with a narrow energy spread. High energy resolution in electron-ion collision studies provides access to individual, possibly even state-selective, reaction pathways. Even in the simple electron-ion collision system (simple compared with the initial ion-atom problem) single and multiple ionization still involve a multitude of complex mechanisms. Besides the direct removal of one or several electrons from the target by electron impact, resonant and non-resonant formation of intermediate multiply excited states which subsequently decay by electron emission is important in single and multiple ionization of ions and atoms. Direct ionization proceeds via one-step or multi-step knock-off mechanisms which can partly be disentangled by studying effects of different projectile species. The role of multiply excited states in the ionization can be experimentally studied in great detail by a further reduction of the initial ion-atom problem. Multiply excited states of atoms and ions can be selectively populated by photon-ion interactions making use of the potential for extreme energy resolution made available at modern synchrotron radiation sources. In the review talk, examples of studies on single and multiple ionization in electron-ion collisions will be discussed in some detail. Electron-ion collision experiments will also be compared with photon-ion interaction studies. Many-electron phenomena have been observed

  9. Collective phenomena in relativistic heavy-ion collisions

    Science.gov (United States)

    Wang, Shan

    1998-12-01

    Collective motion in the final state of relativistic nucleus-nucleus collisions, produced by the release of compressional energy built-up during the stage of maximum density, is widely accepted as a good observable to test models and a useful tool to probe the nuclear equation of state. This dissertation presents an experimental study of nuclear collisions at the Bevalac accelerator at Lawrence Berkeley National Laboratory, with special emphasis on collective phenomena. The main detector used is a time projection chamber with more than two million pixels. Using high statistics measurements of all charged final- state fragments in Au + Au reactions at 0.25, 0.4, 0.6, 0.8, 1.0, and 1.15A GeV, we present a new method to unify the description of light fragment spectra and the three main categories of collective motion: sideward flow, squeeze-out, and transverse expansion. In this alternative representation, the speed of collective expansion is shown to be slowest in the plane of the reaction, and is modulated sinusoidally according to fragment azimuth relative to this plane. This simple yet complete characterization of squeeze-out leads to its interpretation as an in-plane retardation of collective expansion. We test momentum space power law behavior by studying the momentum-space densities of fragments up to 4He. We conclude that the simple momentum-space power law consistently describes light participant fragment production at p⊥/A/ge0.2 GeV/c over a remarkably wide range of transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy in intermediate-energy heavy-ion collisions and in particular, the increase in sideward flow with fragment mass is well described by a momentum- space power law under these conditions. This behavior is consistent with composite fragment formation through a statistical coalescence mechanism in momentum space. Our conclusion supports the use of models without composite formation to interpret flow

  10. Anomalous transport phenomena in Fermi liquids with strong magnetic fluctuations

    International Nuclear Information System (INIS)

    Kontani, Hiroshi

    2008-01-01

    In this paper, we present recent developments in the theory of transport phenomena based on the Fermi liquid theory. In conventional metals, various transport coefficients are scaled according to the quasiparticles relaxation time, τ, which implies that the relaxation time approximation (RTA) holds well. However, such a simple scaling does not hold in many strongly correlated electron systems. The most famous example would be high-T c superconductors (HTSCs), where almost all the transport coefficients exhibit a significant deviation from the RTA results. This issue has been one of the most significant unresolved problems in HTSCs for a long time. Similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). The main goal of this study is to demonstrate whether the anomalous transport phenomena in HTSC is evidence of a non-Fermi liquid ground state, or just RTA violation in strongly correlated Fermi liquids. Another goal is to establish a unified theory of anomalous transport phenomena in metals with strong magnetic fluctuations. For these purposes, we develop a method for calculating various transport coefficients beyond the RTA by employing field theoretical techniques. In a Fermi liquid, an excited quasiparticle induces other excited quasiparticles by collision, and current due to these excitations is called a current vertex correction (CVC). Landau noticed the existence of CVC first, which is indispensable for calculating transport coefficients in accord with the conservation laws. Here, we develop a transport theory involving resistivity and the Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the CVC. In nearly AF Fermi liquids, we find that the strong backward scattering due to AF fluctuations induces the CVC with prominent momentum dependence. This feature of the CVC can account for the significant enhancement in the Hall coefficient, magnetoresistance

  11. Computational transport phenomena of fluid-particle systems

    CERN Document Server

    Arastoopour, Hamid; Abbasi, Emad

    2017-01-01

    This book concerns the most up-to-date advances in computational transport phenomena (CTP), an emerging tool for the design of gas-solid processes such as fluidized bed systems. The authors examine recent work in kinetic theory and CTP and illustrate gas-solid processes’ many applications in the energy, chemical, pharmaceutical, and food industries. They also discuss the kinetic theory approach in developing constitutive equations for gas-solid flow systems and how it has advanced over the last decade as well as the possibility of obtaining innovative designs for multiphase reactors, such as those needed to capture CO2 from flue gases. Suitable as a concise reference and a textbook supplement for graduate courses, Computational Transport Phenomena of Gas-Solid Systems is ideal for practitioners in industries involved with the design and operation of processes based on fluid/particle mixtures, such as the energy, chemicals, pharmaceuticals, and food processing. Explains how to couple the population balance e...

  12. 8th International symposium on transport phenomena in combustion

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The 8th International Symposium on Transport Phenomena in Combustion will be held in San Francisco, California, U.S.A., July 16-20, 1995, under the auspices of the Pacific Center of Thermal-Fluids Engineering. The purpose of the Symposium is to provide a forum for researchers and practitioners from around the world to present new developments and discuss the state of the art and future directions and priorities in the areas of transport phenomena in combustion. The Symposium is the eighth in a series; previous venues were Honolulu 1985, Tokyo 1987, Taipei 1988, Sydney 1991, Beijing 1992, Seoul 1993 and Acapulco 1994, with emphasis on various aspects of transport phenomena. The current Symposium theme is combustion. The Symposium has assembled a balanced program with topics ranging from fundamental research to contemporary applications of combustion theory. Invited keynote lecturers will provide extensive reviews of topics of great interest in combustion. Colloquia will stress recent advances and innovations in fire spread and suppression, and in low NO{sub x} burners, furnaces, boilers, internal combustion engines, and other practical combustion systems. Finally, numerous papers will contribute to the fundamental understanding of complex processes in combustion. This document contains abstracts of papers to be presented at the Symposium.

  13. New methods for analyzing transport phenomena in supersonic ejectors

    International Nuclear Information System (INIS)

    Lamberts, Olivier; Chatelain, Philippe; Bartosiewicz, Yann

    2017-01-01

    Highlights: • Simulation of a supersonic ejector with the open source software for CFD OpenFOAM. • Validation of the numerical tool based on flow structures obtained by schlieren. • Application of the momentum and energy tube analysis tools to a supersonic ejector. • Extension of this framework to exergy to construct exergy transport tubes. • Quantification of local transfers and losses of exergy within the ejector. - Abstract: This work aims at providing novel insights into the quantification and the location of the transfers and the irreversibilities within supersonic ejectors, and their connection with the entrainment. In this study, we propose two different and complementary approaches. First of all, recent analysis tools based on momentum and energy tubes (Meyers and Meneveau (2013)) are extended to the present compressible flow context and applied to the mean-flow structure of turbulent flow within the ejector. Furthermore, the transport equation for the mean-flow total exergy is derived and exergy transport tubes are proposed as a tool for the investigation of transport phenomena within supersonic ejectors. In addition to this topological approach, an analysis based on classical stream tubes is performed in order to quantitatively investigate transfers between the primary and the secondary streams all along the ejector. Finally, the present work identifies the location of exergy losses and their origins. Throughout this analysis, new local and cumulative parameters related to transfers and irreversibilities are introduced. The proposed methodology sheds light on the complex phenomena at play and may serve as a basis for the analysis of transport phenomena within supersonic ejectors. For the ejector under consideration, although global transfers are more important in on-design conditions, it is shown that the net gain in exergy of the secondary stream is maximum for a value of the back pressure that is close to the critical back pressure, as

  14. Transport phenomena and drying of solids and particulate materials

    CERN Document Server

    Lima, AG

    2014-01-01

    The purpose of this book, Transport Phenomena and Drying of Solids and Particulate Materials, is to provide a collection of recent contributions in the field of heat and mass transfer, transport phenomena, drying and wetting of solids and particulate materials. The main benefit of the book is that it discusses some of the most important topics related to the heat and mass transfer in solids and particulate materials. It includes a set of new developments in the field of basic and applied research work on the physical and chemical aspects of heat and mass transfer phenomena, drying and wetting processes, namely, innovations and trends in drying science and technology, drying mechanism and theory, equipment, advanced modelling, complex simulation and experimentation. At the same time, these topics will be going to the encounter of a variety of scientific and engineering disciplines. The book is divided in several chapters that intend to be a resume of the current state of knowledge for benefit of professional c...

  15. Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian

    An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... surpasses batteries in important areas, fundamental research is still required to improve durability and performance. Particularly the transport of methanol and water within the cell structure is difficult to study in-situ. A demand therefore exist for the fundamental development of mathematical models...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...

  16. Transport phenomena of nanoparticles in plants and animals/humans.

    Science.gov (United States)

    Anjum, Naser A; Rodrigo, Miguel Angel Merlos; Moulick, Amitava; Heger, Zbynek; Kopel, Pavel; Zítka, Ondřej; Adam, Vojtech; Lukatkin, Alexander S; Duarte, Armando C; Pereira, Eduarda; Kizek, Rene

    2016-11-01

    The interaction of a plethora nanoparticles with major biota such as plants and animals/humans has been the subject of various multidisciplinary studies with special emphasis on toxicity aspects. However, reports are meager on the transport phenomena of nanoparticles in the plant-animal/human system. Since plants and animals/humans are closely linked via food chain, discussion is imperative on the main processes and mechanisms underlying the transport phenomena of nanoparticles in the plant-animal/human system, which is the main objective of this paper. Based on the literature appraised herein, it is recommended to perform an exhaustive exploration of so far least explored aspects such as reproducibility, predictability, and compliance risks of nanoparticles, and insights into underlying mechanisms in context with their transport phenomenon in the plant-animal/human system. The outcomes of the suggested studies can provide important clues for fetching significant benefits of rapidly expanding nanotechnology to the plant-animal/human health-improvements and protection as well. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Transport of intense ion beams

    International Nuclear Information System (INIS)

    Lambertson, G.; Laslett, L.J.; Smith, L.

    1977-01-01

    The possibility of using intense bursts of heavy ions to initiate an inertially confined fusion reaction has stimulated interest in the transport of intense unneutralized heavy ion beams by quadrupole or solenoid systems. This problem was examined in some detail, using numerical integration of the coupled envelope equations for the quadrupole case. The general relations which emerge are used to develop examples of high energy transport systems and as a basis for discussing the limitations imposed by a transport system on achievable intensities for initial acceleration

  18. Influence of coupling phenomena on the transport through compacted clays

    Energy Technology Data Exchange (ETDEWEB)

    Rosanne, M.; Koudina, N.; Adler, P.M. [IPGP, Paris (France); Tevissen, E. [ANDRA, Dept. Etude-Experimentation et Calcul, Chatenay Malabry (France)

    2001-07-01

    Our principal motivation was to study the influence of the coupling phenomena on transport through compacted clays. Coupled transports may occur when a pressure gradient {nabla}P, and electrical field E and a concentration gradient {nabla}C interact. These three gradients induce three fluxes. A flow is generated characterized by the seepage velocity U; a solute flux J{sub L} and a current density I are generated. Close to equilibrium, when the gradients are not to large, the problem is linear and the fluxes are linear functions of the gradients. A first series of experiments was performed with argillite to determine the diagonal properties, i.e., permeability, conductivity, and diffusion coefficient. In a second series of experiments, the voltage resulting from an imposed concentration gradient between two reservoirs separated by a clay sample was systematically measured; this corresponds to the coefficient L{sub 13}. (orig.)

  19. Turbulent transport of energetic ions

    International Nuclear Information System (INIS)

    Dannert, Tilman; Hauff, Thilo; Jenko, Frank; Guenter, Sibylle

    2006-01-01

    Approaching ITER operation, the issue of anomalous transport of fast particles becomes more and more important. This is partly because the ITER heating and current drive system relies heavily on neutral beam injection. Moreover burning plasmas are heated by fast fusion α particles.Fusion α particles are characterised by a fixed energy and an isotropic velocity distribution. Therefore they have gyroradii one magnitude larger than the thermal ions. The dependency of the particle diffusion of α test particles on the Kubo number K = VExBτc/λc (VExB mean E x B velocity, τc, λc correlation time and length of the turbulent potential) is presented. For different turbulent regimes, different dependency of the diffusion on the gyroradius is found. For large Kubo numbers, the transport is found to remain constant for gyroradii up to the correlation length of the potential, whereas it is drastically reduced in the small Kubo number regime.In the second part, a model for beam ions injected along the equilibrium magnetic field is described. The beam ions are treated gyrokinetically in a self-consistent way with the equilibrium distribution function taken as a shifted Maxwellian. The implications of such a model for the Vlasov equation, the field equations, and the calculation of moments and fluxes are discussed. Linear and nonlinear results, obtained with the gyrokinetic flux tube code GENE show the existence of a new instability driven by fast beam ions. The instability has a maximum growth rate at perpendicular wave numbers of kyρs ∼ 0.15 and depends mainly on the beam velocity and the density gradient of the beam ions. This instability leads to a replacement of bulk ion particle transport by fast ion particle transport, connected to a strongly enhanced heat flux. In the presence of this instability, the turbulent particle and heat transport is dominated by fast ions

  20. Modelling transport phenomena in a multi-physics context

    Science.gov (United States)

    Marra, Francesco

    2015-01-01

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  1. Modelling transport phenomena in a multi-physics context

    Energy Technology Data Exchange (ETDEWEB)

    Marra, Francesco [Dipartimento di Ingegneria Chimica e Alimentare - Università degli studi di Salerno Via Ponte Don Melillo - 84084 Fisciano SA (Italy)

    2015-01-22

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating.

  2. Modelling transport phenomena in a multi-physics context

    International Nuclear Information System (INIS)

    Marra, Francesco

    2015-01-01

    Innovative heating research on cooking, pasteurization/sterilization, defrosting, thawing and drying, often focuses on areas which include the assessment of processing time, evaluation of heating uniformity, studying the impact on quality attributes of the final product as well as considering the energy efficiency of these heating processes. During the last twenty years, so-called electro-heating-processes (radio-frequency - RF, microwaves - MW and ohmic - OH) gained a wide interest in industrial food processing and many applications using the above mentioned technologies have been developed with the aim of reducing processing time, improving process efficiency and, in many cases, the heating uniformity. In the area of innovative heating, electro-heating accounts for a considerable portion of both the scientific literature and commercial applications, which can be subdivided into either direct electro-heating (as in the case of OH heating) where electrical current is applied directly to the food or indirect electro-heating (e.g. MW and RF heating) where the electrical energy is firstly converted to electromagnetic radiation which subsequently generates heat within a product. New software packages, which make easier solution of PDEs based mathematical models, and new computers, capable of larger RAM and more efficient CPU performances, allowed an increasing interest about modelling transport phenomena in systems and processes - as the ones encountered in food processing - that can be complex in terms of geometry, composition, boundary conditions but also - as in the case of electro-heating assisted applications - in terms of interaction with other physical phenomena such as displacement of electric or magnetic field. This paper deals with the description of approaches used in modelling transport phenomena in a multi-physics context such as RF, MW and OH assisted heating

  3. Numerical investigations for insulation particle transport phenomena in water flow

    International Nuclear Information System (INIS)

    Krepper, E.; Grahn, A.; Alt, S.; Kaestner, W.; Kratzsch, A.; Seeliger, A.

    2005-01-01

    The investigation of insulation debris generation, transport and sedimentation gains importance regarding the reactor safety research for PWR and BWR considering the long term behaviour of emergency core coolant systems during all types of LOCA. The insulation debris released near the break during LOCA consists of a mixture of very different particles concerning size, shape, consistence and other properties. Some fraction of the released insulation debris will be transported into the reactor sump where it may affect emergency core cooling. Open questions of generic interest are e.g. the sedimentation of the insulation debris in a water pool, possible re-suspension, transport in the sump water flow, particle load on strainers and corresponding difference pressure. A joint research project in cooperation with Institute of Process Technology, Process Automation and Measuring Technology (IPM) Zittau deals with the experimental investigation and the development of CFD models for the description of particle transport phenomena in coolant flow. While experiments are performed at the IPM-Zittau, theoretical work is concentrated at Forschungszentrum Rossendorf. In the present paper the basic concepts for CFD modelling are described and first results including feasibility studies are shown. During the ongoing work further results are expected. (author)

  4. Kinetic theory of nonlinear transport phenomena in complex plasmas

    International Nuclear Information System (INIS)

    Mishra, S. K.; Sodha, M. S.

    2013-01-01

    In contrast to the prevalent use of the phenomenological theory of transport phenomena, a number of transport properties of complex plasmas have been evaluated by using appropriate expressions, available from the kinetic theory, which are based on Boltzmann's transfer equation; in particular, the energy dependence of the electron collision frequency has been taken into account. Following the recent trend, the number and energy balance of all the constituents of the complex plasma and the charge balance on the particles is accounted for; the Ohmic loss has also been included in the energy balance of the electrons. The charging kinetics for the complex plasma comprising of uniformly dispersed dust particles, characterized by (i) uniform size and (ii) the Mathis, Rumpl, and Nordsieck power law of size distribution has been developed. Using appropriate expressions for the transport parameters based on the kinetic theory, the system of equations has been solved to investigate the parametric dependence of the complex plasma transport properties on the applied electric field and other plasma parameters; the results are graphically illustrated.

  5. Transport phenomena in fuel cells : from microscale to macroscale

    Energy Technology Data Exchange (ETDEWEB)

    Djilali, N. [Victoria Univ., BC (Canada). Dept. of Mechanical Engineering]|[Victoria Univ., BC (Canada). Inst. for Integrated Energy Systems

    2006-07-01

    Proton Exchange Membrane (PEM) fuel cells rely on an array of thermofluid transport processes for the regulated supply of reactant gases and the removal of by-product heat and water. Flows are characterized by a broad range of length and time scales that take place in conjunction with reaction kinetics in a variety of regimes and structures. This paper examined some of the challenges related to computational fluid dynamics (CFD) modelling of PEM fuel cell transport phenomena. An overview of the main features, components and operation of PEM fuel cells was followed by a discussion of the various strategies used for component modelling of the electrolyte membrane; the gas diffusion layer; microporous layer; and flow channels. A review of integrated CFD models for PEM fuel cells included the coupling of electrochemical thermal and fluid transport with 3-D unit cell simulations; air-breathing micro-structured fuel cells; and stack level modelling. Physical models for modelling of transport at the micro-scale were also discussed. Results of the review indicated that the treatment of electrochemical reactions in a PEM fuel cell currently combines classical reaction kinetics with solutions procedures to resolve charged species transport, which may lead to thermodynamically inconsistent solutions for more complex systems. Proper representation of the surface coverage of all the chemical species at all reaction sites is needed, and secondary reactions such as platinum (Pt) dissolution and oxidation must be accounted for in order to model and understand degradation mechanisms in fuel cells. While progress has been made in CFD-based modelling of fuel cells, functional and predictive capabilities remain a challenge because of fundamental modelling and material characterization deficiencies in ionic and water transport in polymer membranes; 2-phase transport in porous gas diffusion electrodes and gas flow channels; inadequate macroscopic modelling and resolution of catalyst

  6. Concentration polarization: Electrodeposition and transport phenomena at overlimiting current

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Peder

    a numerical sharp-interface model describing the electrode growth. This model differs from the established phase-field models, in that it is applicable at overlimiting current and implements electrode reactions in a consistent way. Comparison of the sharp-interface model to the results of the stability...... methods. The initial study concerns a fundamental problem in the study of concentration polarization at overlimiting current, namely the emergence of an extended space-charge region near the ion-selective interface. Based on the so-called quasi-uniform charge density assumption (QCD), we develop...... this coupled chemical and transport effect using two simple models of the reaction kinetics. The principal investigations are performed using numerical simulations, but in addition we derive an analytical model for the transport in the system. The analytical model reveals an important link between the current...

  7. Radiation transport phenomena and modeling - part A: Codes

    International Nuclear Information System (INIS)

    Lorence, L.J.

    1997-01-01

    The need to understand how particle radiation (high-energy photons and electrons) from a variety of sources affects materials and electronics has motivated the development of sophisticated computer codes that describe how radiation with energies from 1.0 keV to 100.0 GeV propagates through matter. Predicting radiation transport is the necessary first step in predicting radiation effects. The radiation transport codes that are described here are general-purpose codes capable of analyzing a variety of radiation environments including those produced by nuclear weapons (x-rays, gamma rays, and neutrons), by sources in space (electrons and ions) and by accelerators (x-rays, gamma rays, and electrons). Applications of these codes include the study of radiation effects on electronics, nuclear medicine (imaging and cancer treatment), and industrial processes (food disinfestation, waste sterilization, manufacturing.) The primary focus will be on coupled electron-photon transport codes, with some brief discussion of proton transport. These codes model a radiation cascade in which electrons produce photons and vice versa. This coupling between particles of different types is important for radiation effects. For instance, in an x-ray environment, electrons are produced that drive the response in electronics. In an electron environment, dose due to bremsstrahlung photons can be significant once the source electrons have been stopped

  8. Finite-orbit-width effect and the radial electric field in neoclassical transport phenomena

    International Nuclear Information System (INIS)

    Satake, S.; Okamoto, M.; Nakajima, N.; Sugama, H.; Yokoyama, M.; Beidler, C.D.

    2005-01-01

    Modeling and detailed simulation of neoclassical transport phenomena both in 2D and 3D toroidal configurations are shown. The emphasis is put on the effect of finiteness of the drift-orbit width, which brings a non-local nature to neoclassical transport phenomena. Evolution of the self-consistent radial electric field in the framework of neoclassical transport is also investigated. The combination of Monte-Carlo calculation for ion transport and numerical solver of ripple-averaged kinetic equation for electrons makes it possible to calculate neoclassical fluxes and the time evolution of the radial electric field in the whole plasma region, including the finite-orbit-width (FOW) effects and global evolution of geodesic acoustic mode (GAM). The simulation results show that the heat conductivity around the magnetic axis is smaller than that obtained from standard neoclassical theory and that the evolution of GAM oscillation on each flux surface is coupled with other surfaces if the FOW effect is significant. A global simulation of radial electric field evolution in a non-axisymmetric plasma is also shown. (author)

  9. Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

    International Nuclear Information System (INIS)

    Soler, J.M.

    1999-09-01

    Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

  10. Coupled Transport Phenomena in the Opalinus Clay: Implications for Radionuclide Transport

    Energy Technology Data Exchange (ETDEWEB)

    Soler, J.M.

    1999-09-01

    Coupled phenomena (thermal and chemical osmosis, hyperfiltration, coupled diffusion, thermal diffusion, thermal filtration, Dufour effect) may play an important role in fluid, solute and heat transport in clay-rich formations, such as the Opalinus Clay (OPA), which are being considered as potential hosts for radioactive waste repositories. In this study, the potential effects of coupled phenomena on radionuclide transport in the vicinity of a repository for vitrified high-level radioactive waste (HLW) and spent nuclear fuel (SF) hosted by the Opalinus Clay, at times equal to or greater than the expected lifetime of the waste canisters (about 1000 years), have been addressed. Firstly, estimates of the solute fluxes associated with chemical osmosis, hyperfiltration, thermal diffusion and thermal osmosis have been calculated. Available experimental data concerning coupled transport phenomena in compacted clays, and the hydrogeological and geochemical conditions to which the Opalinus Clay is subject, have been used for these estimates. These estimates suggest that thermal osmosis is the only coupled transport mechanism that could have a strong impact on solute and fluid transport in the vicinity of the repository. Secondly, estimates of the heat fluxes associated with thermal filtration and the Dufour effect in the vicinity of the repository have been calculated. The calculated heat fluxes are absolutely negligible compared to the heat flux caused by thermal conduction. As a further step to obtain additional insight into the effects of coupled phenomena on solute transport, the solute fluxes associated with advection, chemical diffusion, thermal and chemical osmosis, hyperfiltration and thermal diffusion have been incorporated into a simple one-dimensional transport equation. The analytical solution of this equation, with appropriate parameters, shows again that thermal osmosis is the only coupled transport mechanism that could have a strong effect on repository

  11. Modeling of transport phenomena in concrete porous media.

    Science.gov (United States)

    Plecas, Ilija

    2014-02-01

    Two fundamental concerns must be addressed when attempting to isolate low-level waste in a disposal facility on land. The first concern is isolating the waste from water, or hydrologic isolation. The second is preventing movement of the radionuclides out of the disposal facility, or radionuclide migration. Particularly, we have investigated here the latter modified scenario. To assess the safety for disposal of radioactive waste-concrete composition, the leakage of 60Co from a waste composite into a surrounding fluid has been studied. Leakage tests were carried out by the original method, developed at the Vinča Institute. Transport phenomena involved in the leaching of a radioactive material from a cement composite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source: an equation for diffusion coupled to a first-order equation, and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-y mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center.

  12. Dissipative phenomena in deep inelastic heavy ion collisions

    International Nuclear Information System (INIS)

    Gross, D.H.E.; Krappe, H.J.; Lindenberger, K.H.; Lipperheide, R.; Moehring, K.

    1978-01-01

    During this meeting the following theoretical concepts for deep-inelastic heavy ion reactions were discussed: the energy transfer and friction, direct or statistical mechanisms, dissipation and fluctuation. (WL) [de

  13. Prediction of transport phenomena in near and far field: interaction solid phase/fluid phase

    International Nuclear Information System (INIS)

    Mingarro, E.

    1995-01-01

    The prediction of transport phenomena in near and far field is presented in the present report. The study begins with the analysis of solid phases stability: solubility of storage waste: UO 2 and solubility of radionuclides the redox and sorption-desorption conditions are the last aspects studied to predict the transport phenomena

  14. Impact of Disorder on Spin Dependent Transport Phenomena

    KAUST Repository

    Saidaoui, Hamed

    2016-07-03

    The impact of the spin degree of freedom on the transport properties of electrons traveling through magnetic materials has been known since the pioneer work of Mott [1]. Since then it has been demonstrated that the spin angular momentum plays a key role in the scattering process of electrons in magnetic multilayers. This role has been emphasized by the discovery of the Giant Magnetoresistance in 1988 by Fert and Grunberg [2, 3]. Among the numerous applications and effects that emerged in mesoscopic devices two mechanisms have attracted our attention during the course of this thesis: the spin transfer torque and the spin Hall effects. The former consists in the transfer of the spin angular momentum from itinerant carriers to local magnetic moments [4]. This mechanism results in the current-driven magnetization switching and excitations, which has potential application in terms of magnetic data storage and non-volatile memories. The latter, spin Hall effect, is considered as well to be one of the most fascinating mechanisms in condensed matter physics due to its ability of generating non-equilibrium spin currents without the need for any magnetic materials. In fact the spin Hall effect relies only on the presence of the spin-orbit interaction in order to create an imbalance between the majority and minority spins. The objective of this thesis is to investigate the impact of disorder on spin dependent transport phenomena. To do so, we identified three classes of systems on which such disorder may have a dramatic influence: (i) antiferromagnetic materials, (ii) impurity-driven spin-orbit coupled systems and (iii) two dimensional semiconducting electron gases with Rashba spin-orbit coupling. Antiferromagnetic materials - We showed that in antiferromagnetic spin-valves, spin transfer torque is highly sensitive to disorder, which prevents its experimental observation. To solve this issue, we proposed to use either a tunnel barrier as a spacer or a local spin torque using

  15. Faster Heavy Ion Transport for HZETRN

    Science.gov (United States)

    Slaba, Tony C.

    2013-01-01

    The deterministic particle transport code HZETRN was developed to enable fast and accurate space radiation transport through materials. As more complex transport solutions are implemented for neutrons, light ions (Z heavy ion (Z > 2) transport algorithm in HZETRN is reviewed, and a simple modification is shown to provide an approximate 5x decrease in execution time for galactic cosmic ray transport. Convergence tests and other comparisons are carried out to verify that numerical accuracy is maintained in the new algorithm.

  16. Exotic phenomena in collisions of very heavy ions

    International Nuclear Information System (INIS)

    Soff, G.; Mueller, U.; Schramm, S.; de Reus, T.; Mehler, G.; Reinhardt, J.; Mueller, B.; Greiner, W.

    1987-01-01

    Over the last decade their knowledge on atomic structure of superheavy quasimolecules in the range 110 ≤ Z/sub tot/ ≤ 188 has increased considerably. Heavy ion collisions, in which superheavy quasimolecules are formed for a short period of time, offer them a unique tool to investigate the electronic structure of ultra-high Z-systems, which are not otherwise accessible to experiment. Comparison of K-vacancy formation, δ-electron and positron emission with available experimental data suggests the validity of the quasimolecular picture, which will be taken as the theoretical framework of these calculations. To exemplify current theoretical investigations three different topics will be discussed. After a presentation of the underlying theoretical framework for ionization processes the possibility to employ δ-electron emission as a clock to measure nuclear reaction times in intermediate energy collisions of very heavy ions will be sketched. Besides the phenomenon of vacuum decay into a new twofold negatively charged stable vacuum ground state, electron excitation in heavy ion collisions may be employed for the determination of delay and deceleration times on the nuclear time scale, i.e. offering an atomic clock, operating in the range 10 -21 - 10 -24 s. In deep-inelastic heavy ion collisions this provides a test for classical nuclear reaction models. In collisions at intermediate energies an independent measurement of the deceleration time is of interest for comparison, e.g., with the results of the pion bremsstrahlung model. After that the influence of one or more pockets in the ion scattering potential on the energy distribution of emitted positrons within a quantum mechanical framework is investigated. Finally phenomenological corrections to the Dirac equation and its consequences on electron binding energies in heavy and superheavy atoms is briefly considered. 42 references, 5 figures

  17. Ion age transport: developing devices beyond electronics

    Science.gov (United States)

    Demming, Anna

    2014-03-01

    There is more to current devices than conventional electronics. Increasingly research into the controlled movement of ions and molecules is enabling a range of new technologies. For example, as Weihua Guan, Sylvia Xin Li and Mark Reed at Yale University explain, 'It offers a unique opportunity to integrate wet ionics with dry electronics seamlessly'. In this issue they provide an overview of voltage-gated ion and molecule transport in engineered nanochannels. They cover the theory governing these systems and fabrication techniques, as well as applications, including biological and chemical analysis, and energy conversion [1]. Studying the movement of particles in nanochannels is not new. The transport of materials in rock pores led Klinkenberg to describe an analogy between diffusion and electrical conductivity in porous rocks back in 1951 [2]. And already in 1940, Harold Abramson and Manuel Gorin noted that 'When an electric current is applied across the living human skin, the skin may be considered to act like a system of pores through which transfer of substances like ragweed pollen extract may be achieved both by electrophoretic and by diffusion phenomena' [3]. Transport in living systems through pore structures on a much smaller scale has attracted a great deal of research in recent years as well. The selective transport of ions and small organic molecules across the cell membrane facilitates a number of functions including communication between cells, nerve conduction and signal transmission. Understanding these processes may benefit a wide range of potential applications such as selective separation, biochemical sensing, and controlled release and drug delivery processes. In Germany researchers have successfully demonstrated controlled ionic transport through nanopores functionalized with amine-terminated polymer brushes [4]. The polymer nanobrushes swell and shrink in response to changes in temperature, thus opening and closing the nanopore passage to ionic

  18. Changes in ion transport in inflammatory disease

    Directory of Open Access Journals (Sweden)

    Eisenhut Michael

    2006-03-01

    Full Text Available Abstract Ion transport is essential for maintenance of transmembranous and transcellular electric potential, fluid transport and cellular volume. Disturbance of ion transport has been associated with cellular dysfunction, intra and extracellular edema and abnormalities of epithelial surface liquid volume. There is increasing evidence that conditions characterized by an intense local or systemic inflammatory response are associated with abnormal ion transport. This abnormal ion transport has been involved in the pathogenesis of conditions like hypovolemia due to fluid losses, hyponatremia and hypokalemia in diarrhoeal diseases, electrolyte abnormalites in pyelonephritis of early infancy, septicemia induced pulmonary edema, and in hypersecretion and edema induced by inflammatory reactions of the mucosa of the upper respiratory tract. Components of membranous ion transport systems, which have been shown to undergo a change in function during an inflammatory response include the sodium potassium ATPase, the epithelial sodium channel, the Cystic Fibrosis Transmembrane Conductance Regulator and calcium activated chloride channels and the sodium potassium chloride co-transporter. Inflammatory mediators, which influence ion transport are tumor necrosis factor, gamma interferon, interleukins, transforming growth factor, leukotrienes and bradykinin. They trigger the release of specific messengers like prostaglandins, nitric oxide and histamine which alter ion transport system function through specific receptors, intracellular second messengers and protein kinases. This review summarizes data on in vivo measurements of changes in ion transport in acute inflammatory conditions and in vitro studies, which have explored the underlying mechanisms. Potential interventions directed at a correction of the observed abnormalities are discussed.

  19. Resonant ion transport in EBT

    International Nuclear Information System (INIS)

    Hastings, D.E.; Jaeger, E.F.; Hedrick, C.L.; Tolliver, J.S.

    1983-05-01

    We use a model for the ELMO Bumpy Torus as a bumpy cylinder with a toroidally induced vertical drift imposed on the plasma. With this model we obtain the neoclassical plasma-transport coefficients for ions in both the banana and plateau resonant regimes. The problem of solving the linearized bounce-averaged drift kinetic equation is formulated as a variational principle, which is shown to be valid for both the banana and plateau regimes. We use limiting forms of this principle to obtain a continuous collisionality approximation to the energy-dependent flux. We then use this approximation to obtain analytic formulae for the particle- and energy-diffusion coefficients. These are shown to give excellent agreement with numerical results

  20. Center for low-gravity fluid mechanics and transport phenomena

    Science.gov (United States)

    Kassoy, D. R.; Sani, R. L.

    1991-01-01

    Research projects in several areas are discussed. Mass transport in vapor phase systems, droplet collisions and coalescence in microgravity, and rapid solidification of undercooled melts are discussed.

  1. Transition phenomena and thermal transport property in LHD plasmas with an electron internal transport barrier

    International Nuclear Information System (INIS)

    Shimozuma, T.; Kubo, S.; Idei, H.

    2005-01-01

    Two kinds of improved core confinement were observed during centrally focused Electron Cyclotron Heating (ECH) into plasmas sustained by Counter (CNTR) and Co Neutral Beam Injections (NBI) in the Large Helical Device (LHD). One shows transition phenomena to the high-electron-temperature state and has a clear electron Internal Transport Barrier (eITB) in CNTR NBI plasma. Another has no clear transition and no ECH power threshold, but shows a broad high temperature profiles with moderate temperature gradient, which indicates the improved core confinement with additional ECH in Co NBI plasma. The electron heat transport characteristics of these plasmas were directly investigated by using the heat pulse propagation excited by Modulated ECH (MECH). The difference of the features could be caused by the existence of the m/n=2/1 rational surface or island determined by the direction of NBI beam-driven current. (author)

  2. Transition phenomena and thermal transport properties in LHD plasmas with an electron internal transport barrier

    International Nuclear Information System (INIS)

    Shimozuma, T.; Kubo, S.; Idei, H.; Inagaki, S.; Tamura, N.; Tokuzawa, T.; Morisaki, T.; Watanabe, K.Y.; Ida, K.; Yamada, I.; Narihara, K.; Muto, S.; Yokoyama, M.; Yoshimura, Y.; Notake, T.; Ohkubo, K.; Seki, T.; Saito, K.; Kumazawa, R.; Mutoh, T.; Watari, T.; Komori, A.

    2005-01-01

    Two types of improved core confinement were observed during centrally focused electron cyclotron heating (ECH) into plasmas sustained by counter (CNTR) and Co neutral beam injections (NBI) in the Large Helical Device. The CNTR NBI plasma displayed transition phenomena to the high-electron-temperature state and had a clear electron internal transport barrier, while the Co NBI plasma did not show a clear transition or an ECH power threshold but showed broad high temperature profiles with moderate temperature gradient. This indicated that the Co NBI plasma with additional ECH also had an improved core confinement. The electron heat transport characteristics of these plasmas were directly investigated using heat pulse propagation excited by modulated ECH. These effects appear to be related to the m/n = 2/1 rational surface or the island induced by NBI beam-driven current

  3. Enhanced transport phenomena in CO2 sequestration and CO2 EOR

    NARCIS (Netherlands)

    Farajzadeh, R.

    2009-01-01

    The results of this thesis give insight into the (mass)-transfer during flow of gases, especially CO2, in various gas-liquid systems. A number of experiments was performed to investigate the transport phenomena through interfaces with and without surfactant monolayers. The observed phenomena have

  4. Diffusion and transport phenomena in a collisional magnetoplasma ...

    Indian Academy of Sciences (India)

    Boltzmann-transport equation is analytically solved for two-component magnetoplasma using Chapman-Enskog analysis to include collisional diffusion transport having anisotropies in both streaming velocity and temperature components. The modified collisional integrals are analytically solved with flux integrals and ...

  5. Ion heat transport studies in JET

    DEFF Research Database (Denmark)

    Mantica, P; Angioni, C; Baiocchi, B

    2011-01-01

    Detailed experimental studies of ion heat transport have been carried out in JET exploiting the upgrade of active charge exchange spectroscopy and the availability of multi-frequency ion cyclotron resonance heating with 3He minority. The determination of ion temperature gradient (ITG) threshold a...

  6. Numerical Study of Electrolyte Wetting Phenomena in the Electrode of Lithium Ion Battery Using Lattice Boltzmann Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Gun [Seoul Nat' l Univ., Seoul (Korea, Republic of); Jeon, Dong Hyup [Dongguk Univ., Seoul (Korea, Republic of)

    2014-04-15

    The electrolyte wetting phenomena in the electrode of lithium ion battery is studied numerically using a multiphase lattice Boltzmann method (LBM). When a porous electrode is compressed during roll-pressing process, the porosity and thickness of the compressed electrode are changed, which can affect its wettability. In this study, the change in electrolyte distribution and degree of saturation as a result of varying the compression ratio are investigated with two-dimensional LBM approach. We found that changes in the electrolyte transport path are caused by a reduction in through-plane pore size and result in a decrease in the wettability of the compressed electrode.

  7. Lab-scale tests on ISV vapor transport phenomena

    International Nuclear Information System (INIS)

    Farnsworth, R.K.; Gardner, B.M.

    1996-01-01

    In situ vitrification (ISV) is a promising technology for remediating buried waste sites and contaminated soil sites. However, concerns exist that low soil permeabilities may limit vapor transport away from the advancing melt front and cause a melt expulsion that breaches ISV containment. As a result, two ISV lab tests were conducted at the Idaho National Engineering Laboratory (INEL) using INEL soil (permeability: 10 -6 cm/s) and a low permeability (10 -10 cm/s) clay material. The clay test also had a ceramic tube inserted vertically through the center of the area being melted to provide one-dimensional data on vapor transport. Results confirm that low soil permeabilities can limit vapor transport away from the advancing ISV melt front. In addition, peak pressures inside the ceramic tube were significantly greater than those outside the tube, indicating the importance of horizontal vapor transport around the advancing ISV melt front

  8. Nitrogen transport during ion nitriding of austenitic stainless steel

    International Nuclear Information System (INIS)

    Parascandola, S.

    2001-09-01

    The work is structured as follows: In Chapter 2 fundamental transport concepts and phenomena and approaches to transport modeling are introduced. In Chapter 3 details are presented concerning the material under investigation, the material modification process, and the ion beam analytical techniques. In Chapter 4 experimental and modeling results are presented and discussed. Issues that are directly addressed include: The structural nature of the nitrogen enriched layer. The diffusion mechanism of nitrogen. The role of potential incorporation and release mechanisms. The evolution of the thickness of the nitrogen enriched layer. The role of the surface oxide layer. (orig.)

  9. Transport phenomena in sharply contrasting media with a diffusion barrier

    International Nuclear Information System (INIS)

    Dvoretskaya, O A; Kondratenko, P S

    2011-01-01

    Using the advection–diffusion equation, we analytically study contaminant transport in a sharply contrasting medium with a diffusion barrier due to localization of a contaminant source in a low-permeability medium. Anomalous diffusion behavior and a crossover between different transport regimes are observed. The diffusion barrier results in exponential attenuation of the source power, retardation of the contaminant plume growth and modification of the concentration distribution at large distances. (paper)

  10. Linear and non-linear ion acoustic phenomena in magnetic multi-dipole discharges

    International Nuclear Information System (INIS)

    Ferreira, J.L.

    1986-12-01

    An experimental study of ion acoustic phenomena in a multi-magnetic-dipole plasma device is presented. The plasma is uniform and free from external field, permitting good observation of space and laboratory plasma phenomena. The major interest was in the observtion of the propagation characterics of solitions and ion acoustic waves in a double plasma configuration. In this experiment plane waves were studied in a plasma composed by a mixture of negative and positive ions. The most important result was the first observation of solitary waves with negative potential, that means rarefaction ion acoustic solitions. The formation of non neutral regions inside the plasma and its relations with the inhibition of electron thermal flux were studied. A bootstrap action enhances the ion acoustic instability which generates an anomalous resistivity self consistently with a potential step. It was observed that this is the mechanism of cold electron thermalization during diffusion through a warn collisionless plasma. The importance of the bootstrap action in ion acoustic double layer formation was experimentally verified by ion acoustic instability inhibition, obtained via induced Landau damping of the ion acoustic spectrum of the instability. (author) [pt

  11. Parametric variations of ion transport in TFTR

    International Nuclear Information System (INIS)

    Scott, S.D.; Ernst, D.

    1993-01-01

    This paper is divided into three roughly independent sections. The first is a historical review of the twenty year history of experimental ion heat transport measurements from many tokamaks. The second is a study of ion heat transport in Ohmic TFTR plasmas which shows that χi ∼ χe ∼ 15χi neo . Thus, ion heat transport is demonstrated to be strongly anomalous even the absence of auxiliary heating. The third section describes the variation of χi with local ion temperature in TFTR during auxiliary heating, with emphasis on characterizing the differecens between transport in the L-mode and supershot regimes. The results are consistent with the conjecture that improved ion energy confinement in supershot plasmas is caused by a high ratio of T 1 /T e

  12. Theory of ion heat transport in tokamaks

    International Nuclear Information System (INIS)

    Gott, Y.V.; Yurchenko, E.I.

    1987-01-01

    Experiments which have been carried out in several tokamaks to determine the ion thermal conductivity show that it is several times the value predicted by the neoclassical theory. A possible explanation for this discrepancy is proposed. When the finite width of a banana is taken into account, there are substantial increases in the heat fluxes which stem from the important contribution of superthermal ions to the transport. If the electron diffusive flux is zero, a systematic account of the ions with E>T leads to an ion heat flux with a finite banana width which is two to four times the neoclassical prediction. The effect of the anomalous nature of the electron flux on the ion heat transport is analyzed. An expression is derived for calculating the ion heat transport over the entire range of collision rates

  13. Kinetic phenomena in charged particle transport in gases, swarm parameters and cross section data

    International Nuclear Information System (INIS)

    Petrovic, Z Lj; Suvakov, M; Nikitovic, Z; Dujko, S; Sasic, O; Jovanovic, J; Malovic, G; Stojanovic, V

    2007-01-01

    In this review we discuss the current status of the physics of charged particle swarms, mainly electrons. The whole field is analysed mainly through its relationship to plasma modelling and illustrated by some recent examples developed mainly by our group. The measurements of the swarm coefficients and the availability of the data are briefly discussed. More time is devoted to the development of complete electron-molecule cross section sets along with recent examples such as NO, CF 4 and HBr. We extend the discussion to the availability of ion and fast neutral data and how swarm experiments may serve to provide new data. As a point where new insight into the kinetics of charge particle transport is provided, the role of kinetic phenomena is discussed and recent examples are listed. We focus here on giving two examples on how non-conservative processes make dramatic effects in transport, the negative absolute mobility and the negative differential conductivity for positrons in argon. Finally we discuss the applicability of swarm data in plasma modelling and the relationship to other fields where swarm experiments and analysis make significant contributions. (topical review)

  14. Dependence of surface smoothing, sputtering and etching phenomena on cluster ion dosage

    CERN Document Server

    Song, J H; Choi, W K

    2002-01-01

    The dependence of surface smoothing and sputtering phenomena of Si (1 0 0) solid surfaces irradiated by CO sub 2 cluster ions on cluster-ion dosage was investigated using an atomic force microscope. The flux and total ion dosage of impinging cluster ions at the acceleration voltage of 50 kV were fixed at 10 sup 9 ions/cm sup 2 s and were scanned from 5x10 sup 1 sup 0 to 5x10 sup 1 sup 3 ions/cm sup 2 , respectively. The density of hillocks induced by cluster ion impact was gradually increased with the dosage up to 5x10 sup 1 sup 1 ions/cm sup 2 , which caused that the irradiated surface became rough from 0.4 to 1.24 nm in root-mean-square roughness (sigma sub r sub m sub s). At the boundary of the ion dosage of 10 sup 1 sup 2 ions/cm sup 2 , the density of the induced hillocks was decreased and sigma sub r sub m sub s was about 1.21 nm, not being deteriorated further. At the dosage of 5x10 sup 1 sup 3 ions/cm sup 2 , the induced hillocks completely disappeared and the surface became very flat as much as sigma...

  15. Electron heat transport studies using transient phenomena in ASDEX Upgrade

    International Nuclear Information System (INIS)

    Jacchia, A.; Angioni, C.; Manini, A.; Ryter, F.; Apostoliceanu, M.; Conway, G.; Fahrbach, H.-U.; Kirov, K.K.; Leuterer, F.; Reich, M.; Sutttrop, W.; Cirant, S.; Mantica, P.; De Luca, F.; Weiland, J.

    2005-01-01

    Experiments in tokamaks suggest that a critical gradient length may cause the resilient behavior of T e profiles, in the absence of ITBs. This agrees in general with ITG/TEM turbulence physics. Experiments in ASDEX Upgrade using modulation techniques with ECH and/or cold pulses demonstrate the existence of a threshold in R/L Te when T e >T i and T e ≤T i . For T e >T i linear stability analyses indicate that electron heat transport is dominated by TEM modes. They agree in the value of the threshold (both T e and n e ) and for the electron heat transport increase above the threshold. The stabilization of TEM modes by collisions yielded by gyro-kinetic calculations, which suggests a transition from TEM to ITG dominated transport at high collisionality, is experimentally demonstrated by comparing heat pulse and steady-state diffusivities. For the T e ∼T i discharges above the threshold the resilience, normalized by T e 3/2 , is similar to that of the TEM dominated cases, despite very different conditions. The heat pinch predicted by fluid modeling of ITG/TEM turbulence is investigated by perturbative transport in off-axis ECH-heated discharges. (author)

  16. Asymmetric ion transport through ion-channel-mimetic solid-state nanopores.

    Science.gov (United States)

    Guo, Wei; Tian, Ye; Jiang, Lei

    2013-12-17

    Both scientists and engineers are interested in the design and fabrication of synthetic nanofluidic architectures that mimic the gating functions of biological ion channels. The effort to build such structures requires interdisciplinary efforts at the intersection of chemistry, materials science, and nanotechnology. Biological ion channels and synthetic nanofluidic devices have some structural and chemical similarities, and therefore, they share some common features in regulating the traverse ionic flow. In the past decade, researchers have identified two asymmetric ion transport phenomena in synthetic nanofluidic structures, the rectified ionic current and the net diffusion current. The rectified ionic current is a diode-like current-voltage response that occurs when switching the voltage bias. This phenomenon indicates a preferential direction of transport in the nanofluidic system. The net diffusion current occurs as a direct product of charge selectivity and is generated from the asymmetric diffusion through charged nanofluidic channels. These new ion transport phenomena and the elaborate structures that occur in biology have inspired us to build functional nanofluidic devices for both fundamental research and practical applications. In this Account, we review our recent progress in the design and fabrication of biomimetic solid-state nanofluidic devices with asymmetric ion transport behavior. We demonstrate the origin of the rectified ionic current and the net diffusion current. We also identify several influential factors and discuss how to build these asymmetric features into nanofluidic systems by controlling (1) nanopore geometry, (2) surface charge distribution, (3) chemical composition, (4) channel wall wettability, (5) environmental pH, (6) electrolyte concentration gradient, and (7) ion mobility. In the case of the first four features, we build these asymmetric features directly into the nanofluidic structures. With the final three, we construct

  17. Experimental transport phenomena and optimization strategies for thermoelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Ehrlich, A C; Gillespie, D J

    1997-07-01

    When a new and promising thermoelectric material is discovered, an effort is undertaken to improve its figure of merit. If the effort is to be more efficient than one of trial and error with perhaps some rule of thumb guidance then it is important to be able to make the connection between experimental data and the underlying material characteristics, electronic and phononic, that influence the figure of merit. Transport and fermiology experimental data can be used to evaluate these material characteristics and thus establish trends as a function of some controllable parameter, such as composition. In this paper some of the generic-materials characteristics, generally believed to be required for a high figure of merit, will be discussed in terms of the experimental approach to their evaluation and optimization. Transport and fermiology experiments will be emphasized and both will be outlined in what they can reveal and what can be obscured by the simplifying assumptions generally used in their interpretation.

  18. On nonequilibrium many-body systems V: ultrafast transport phenomena

    International Nuclear Information System (INIS)

    Freire, V.N.; Vasconcellos, A.R.; Luzzi, R.

    1989-01-01

    The monequilibrium statistical operator method and its accompanying nonlinear quantum transport theory, are used to perform an analytical study of the ultrafast mobility transient of central-valley photoinjected carriers in direct-gap polar semiconductors. Expressions for the time-resolved mobility of the hot carriers are derived. A brief discussion of the carriers' diffusion coefficient is done. (A.C.A.S.) [pt

  19. Nonlinear parametric phenomena in plasma during radio frequency heating in the ion cyclotron frequency range

    International Nuclear Information System (INIS)

    Stepanov, K.N.

    1996-01-01

    Parametric phenomena in plasma which occur due to varying electric fields with the ion cyclotron frequency are reviewed. Beam-like lower hybrid instability emerges in strong pumping fields provided that the transverse relative velocity of particles is larger than the ion thermal speed (υ Ti ). The resulting turbulence and the following numerous manifestations observed experimentally are addressed. The turbulence may prove important for experiments aimed at plasma production or radio frequency (RF) cleaning of metallic surfaces of vacuum chambers in stellarators, tokamaks and helicon devices. In contrast, for a weak field (U Ti ) the kinetic parametric instabilities of ion cyclotron oscillations arise due to electrons. The issues of the turbulence, mathematical modelling, its role in turbulent heating observed on the torsatron Uragan-3M, decay instabilities associated with ion cyclotron oscillations and the triggering of ion quasimodes are considered. (author)

  20. Spin-transport-phenomena in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias Klaus

    2012-07-19

    Assuming that one could deterministically inject, transport, manipulate, store and detect spin information in solid state devices, the well-established concepts of charge-based electronics could be transferred to the spin realm. This thesis explores the injection, transport, manipulation and storage of spin information in metallic conductors, semiconductors, as well as electrical insulators. On the one hand, we explore the spin-dependent properties of semiconducting zinc oxide thin films deposited via laser-molecular beam epitaxy (laser-MBE). After demonstrating that the zinc oxide films fabricated during this thesis have excellent structural, electrical, and optical properties, we investigate the spin-related properties by optical pump/probe, electrical injection/optical detection, and all electrical spin valve-based experiments. The two key results from these experiments are: (i) Long-lived spin states with spin dephasing times of 10 ns at 10 K related to donor bound excitons can be optically addressed. (ii) The spin dephasing times relevant for electrical transport-based experiments are {<=} 2 ns at 10 K and are correlated with structural quality. On the other hand we focus on two topics of current scientific interest: the comparison of the magnetoresistance to the magnetothermopower of conducting ferromagnets, and the investigation of pure spin currents generated in ferromagnetic insulator/normal metal hybrid structures. We investigate the magnetoresistance and magnetothermopower of gallium manganese arsenide and Heusler thin films as a function of external magnetic field orientation. Using a series expansion of the resistivity and Seebeck tensors and the inherent symmetry of the sample's crystal structure, we show that a full quantitative extraction of the transport tensors from such experiments is possible. Regarding the spin currents in ferromagnetic insulator/normal metal hybrid structures we studied the spin mixing conductance in yttrium iron garnet

  1. Light ion beam transport research at NRL

    International Nuclear Information System (INIS)

    Hinshelwood, D.D.; Boller, J.R.; Cooperstein, G.

    1996-01-01

    Transport of light ion beams through low-pressure background gas is under investigation at NRL in support of the light-ion ICF program at Sandia National Laboratories. Scaling experiments and the field solver/orbit code ATHETA have been used to design and construct a focusing, extraction applied-B diode for transport experiments. An active anode source has been developed to provide a high proton fraction in the ion beam and a fast ion turn-on time. A very sensitive Zeeman diagnostic is being developed to determine the net current distribution in the beam/transport system. Both analytical and numerical techniques using several codes are being applied to transport modeling, leading to the capability of full system studies. (author). 1 tab., 5 figs., 10 refs

  2. Light ion beam transport research at NRL

    Energy Technology Data Exchange (ETDEWEB)

    Hinshelwood, D D; Boller, J R; Cooperstein, G [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.; and others

    1997-12-31

    Transport of light ion beams through low-pressure background gas is under investigation at NRL in support of the light-ion ICF program at Sandia National Laboratories. Scaling experiments and the field solver/orbit code ATHETA have been used to design and construct a focusing, extraction applied-B diode for transport experiments. An active anode source has been developed to provide a high proton fraction in the ion beam and a fast ion turn-on time. A very sensitive Zeeman diagnostic is being developed to determine the net current distribution in the beam/transport system. Both analytical and numerical techniques using several codes are being applied to transport modeling, leading to the capability of full system studies. (author). 1 tab., 5 figs., 10 refs.

  3. Numerical modelling of ion transport in flames

    KAUST Repository

    Han, Jie; Belhi, Memdouh; Bisetti, Fabrizio; Sarathy, Mani

    2015-01-01

    that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect

  4. Gas generation phenomena in radioactive waste transportation packaging

    International Nuclear Information System (INIS)

    Nigrey, P.J.

    1998-01-01

    The interaction of radiation from radioactive materials with the waste matrix can lead to the deterioration of the waste form resulting in the possible of gaseous species. Depending on the type and characteristics of the radiation source, the generation of hydrogen may predominate. Since the interaction of alpha particles with the waste form results in significant energy transfer, other gases such as carbon oxides, methane, nitrogen oxides, oxygen, water, and helium are possible. The type of gases produced from the waste forms is determined by the mechanisms involved in the waste degradation. For transuranic wastes, the identified degradation mechanisms are reported to be caused by radiolysis, thermal decomposition or dewatering, chemical corrosion, and bacterial action. While all these mechanisms may be responsible for the building of gases during the storage of wastes, radiolysis and thermal decomposition appear to be main contributors during waste transport operations. (authors)

  5. Suprathermal ion transport in turbulent magnetized plasmas

    International Nuclear Information System (INIS)

    Bovet, A. D.

    2015-01-01

    Suprathermal ions, which have an energy greater than the quasi-Maxwellian background plasma temperature, are present in many laboratory and astrophysical plasmas. In fusion devices, they are generated by the fusion reactions and auxiliary heating. Controlling their transport is essential for the success of future fusion devices that could provide a clean, safe and abundant source of electric power to our society. In space, suprathermal ions include energetic solar particles and cosmic rays. The understanding of the acceleration and transport mechanisms of these particles is still incomplete. Basic plasma devices allow detailed measurements that are not accessible in astrophysical and fusion plasmas, due to the difficulty to access the former and the high temperatures of the latter. The basic toroidal device TORPEX offers an easy access for diagnostics, well characterized plasma scenarios and validated numerical simulations of its turbulence dynamics, making it the ideal platform for the investigation of suprathermal ion transport. This Thesis presents three-dimensional measurements of a suprathermal ion beam injected in turbulent TORPEX plasmas. The combination of uniquely resolved measurements and first principle numerical simulations reveals the general non-diffusive nature of the suprathermal ion transport. A precise characterization of their transport regime shows that, depending on their energies, suprathermal ions can experience either a super diffusive transport or a subdiffusive transport in the same background turbulence. The transport character is determined by the interaction of the suprathermal ion orbits with the turbulent plasma structures, which in turn depends on the ratio between the ion energy and the background plasma temperature. Time-resolved measurements reveal a clear difference in the intermittency of suprathermal ions time-traces depending on the transport regime they experience. Conditionally averaged measurements uncover the influence of

  6. Electric Transport Phenomena of Nanocomposite Organic Polymer Thin Films

    Science.gov (United States)

    Jira, Nicholas C.; Sabirianov, Ildar; Ilie, Carolina C.

    We discuss herein the nanocomposite organic thin film diodes for the use of plasmonic solar cells. This experimental work follows the theoretical calculations done for plasmonic solar cells using the MNPBEM toolbox for MatLab. These calculations include dispersion curves and amount of light scattering cross sections for different metallic nanoparticles. This study gives us clear ideas on what to expect from different metals, allowing us to make the best choice on what to use to obtain the best results. One specific technique for light trapping in thin films solar cells utilizes metal nanoparticles on the surface of the semiconductor. The characteristics of the metal, semiconductor interface allows for light to be guided in between them causing it to be scattered, allowing for more chances of absorption. The samples were fabricated using organic thin films made from polymers and metallic nanoparticles, more specifically Poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) copolymer and silver or gold nanoparticles. The two fabrication methods applied include spin coating and Langmuir-Blodgett technique. The transport properties are obtained by analyzing the I-V curves. We will also discuss the resistance, resistivity, conductance, density of charge carriers. SUNY Oswego SCAC Grant.

  7. Fluid Physical and Transport Phenomena Studies aboard the International Space Station: Planned Experiments

    Science.gov (United States)

    Singh, Bhim S.

    1999-01-01

    This paper provides an overview of the microgravity fluid physics and transport phenomena experiments planned for the International Spare Station. NASA's Office of Life and Microgravity Science and Applications has established a world-class research program in fluid physics and transport phenomena. This program combines the vast expertise of the world research community with NASA's unique microgravity facilities with the objectives of gaining new insight into fluid phenomena by removing the confounding effect of gravity. Due to its criticality to many terrestrial and space-based processes and phenomena, fluid physics and transport phenomena play a central role in the NASA's Microgravity Program. Through widely publicized research announcement and well established peer-reviews, the program has been able to attract a number of world-class researchers and acquired a critical mass of investigations that is now adding rapidly to this field. Currently there arc a total of 106 ground-based and 20 candidate flight principal investigators conducting research in four major thrust areas in the program: complex flows, multiphase flow and phase change, interfacial phenomena, and dynamics and instabilities. The International Space Station (ISS) to be launched in 1998, provides the microgravity research community with a unprecedented opportunity to conduct long-duration microgravity experiments which can be controlled and operated from the Principal Investigators' own laboratory. Frequent planned shuttle flights to the Station will provide opportunities to conduct many more experiments than were previously possible. NASA Lewis Research Center is in the process of designing a Fluids and Combustion Facility (FCF) to be located in the Laboratory Module of the ISS that will not only accommodate multiple users but, allow a broad range of fluid physics and transport phenomena experiments to be conducted in a cost effective manner.

  8. Predictive modelling of edge transport phenomena in ELMy H-mode tokamak fusion plasmas

    International Nuclear Information System (INIS)

    Loennroth, J.-S.

    2009-01-01

    This thesis discusses a range of work dealing with edge plasma transport in magnetically confined fusion plasmas by means of predictive transport modelling, a technique in which qualitative predictions and explanations are sought by running transport codes equipped with models for plasma transport and other relevant phenomena. The focus is on high confinement mode (H-mode) tokamak plasmas, which feature improved performance thanks to the formation of an edge transport barrier. H-mode plasmas are generally characterized by the occurrence of edge localized modes (ELMs), periodic eruptions of particles and energy, which limit confinement and may turn out to be seriously damaging in future tokamaks. The thesis introduces schemes and models for qualitative study of the ELM phenomenon in predictive transport modelling. It aims to shed new light on the dynamics of ELMs using these models. It tries to explain various experimental observations related to the performance and ELM-behaviour of H-mode plasmas. Finally, it also tries to establish more generally the potential effects of ripple-induced thermal ion losses on H-mode plasma performance and ELMs. It is demonstrated that the proposed ELM modelling schemes can qualitatively reproduce the experimental dynamics of a number of ELM regimes. Using a theory-motivated ELM model based on a linear instability model, the dynamics of combined ballooning-peeling mode ELMs is studied. It is shown that the ELMs are most often triggered by a ballooning mode instability, which renders the plasma peeling mode unstable, causing the ELM to continue in a peeling mode phase. Understanding the dynamics of ELMs will be a key issue when it comes to controlling and mitigating the ELMs in future large tokamaks. By means of integrated modelling, it is shown that an experimentally observed increase in the ELM frequency and deterioration of plasma confinement triggered by external neutral gas puffing might be due to a transition from the second to

  9. Particle and heavy ion transport code system; PHITS

    International Nuclear Information System (INIS)

    Niita, Koji

    2004-01-01

    Intermediate and high energy nuclear data are strongly required in design study of many facilities such as accelerator-driven systems, intense pulse spallation neutron sources, and also in medical and space technology. There is, however, few evaluated nuclear data of intermediate and high energy nuclear reactions. Therefore, we have to use some models or systematics for the cross sections, which are essential ingredients of high energy particle and heavy ion transport code to estimate neutron yield, heat deposition and many other quantities of the transport phenomena in materials. We have developed general purpose particle and heavy ion transport Monte Carlo code system, PHITS (Particle and Heavy Ion Transport code System), based on the NMTC/JAM code by the collaboration of Tohoku University, JAERI and RIST. The PHITS has three important ingredients which enable us to calculate (1) high energy nuclear reactions up to 200 GeV, (2) heavy ion collision and its transport in material, (3) low energy neutron transport based on the evaluated nuclear data. In the PHITS, the cross sections of high energy nuclear reactions are obtained by JAM model. JAM (Jet AA Microscopic Transport Model) is a hadronic cascade model, which explicitly treats all established hadronic states including resonances and all hadron-hadron cross sections parametrized based on the resonance model and string model by fitting the available experimental data. The PHITS can describe the transport of heavy ions and their collisions by making use of JQMD and SPAR code. The JQMD (JAERI Quantum Molecular Dynamics) is a simulation code for nucleus nucleus collisions based on the molecular dynamics. The SPAR code is widely used to calculate the stopping powers and ranges for charged particles and heavy ions. The PHITS has included some part of MCNP4C code, by which the transport of low energy neutron, photon and electron based on the evaluated nuclear data can be described. Furthermore, the high energy nuclear

  10. Tokamak fuelling with pellets: Effect of transport phenomena on the injection requirements

    International Nuclear Information System (INIS)

    Lengyel, L.L.

    1979-01-01

    Results of calculations on pellet-plasma interaction that take into account transport phenomena inherent in tokamak plasmas are analyzed. It is shown that the results obtained by different authors on the optimum pellet penetration depth and required pellet injection frequencies, which are partly contradictory, can be explained by means of the different transport processes taken into account or neglected in the calculations concerned. (orig.)

  11. Development of instrumentation in the transport phenomena research in thermal equipment

    International Nuclear Information System (INIS)

    Carvalho Tofani, P. de; Ladeira, L.C.D.

    1983-11-01

    The results obtained from the effort on the acquisition of know-how in experimental reactor thermal during the last years, through the approach of relevant aspects of basic research on transport phenomena applicable to nuclear reactor analysis and conventional thermal equipment based in the simultaneous development of instrumentation and experimental methods are presented. (E.G.) [pt

  12. Transport phenomena through porous screens and openings : from theory to greenhouse practice

    NARCIS (Netherlands)

    Miguel, A.A.F.

    1998-01-01

    The study of transport phenomena in multi-zone enclosures with permeable boundaries is fundamental for indoor climate control management. In this study, aspects concerning the air exchange through porous screens and openings, and heat transfer between the enclosure surface and inside air,

  13. Mathematical modelling of transport phenomena in radioactive waste-cement-bentonite matrix

    International Nuclear Information System (INIS)

    Plecas, Ilija; Dimovic, Slavko

    2010-01-01

    Document available in extended abstract form only. The leaching rate of 137 Cs from spent mix bead (anion and cation) exchange resins in a cement-bentonite matrix has been studied. Transport phenomena involved in the leaching of a radioactive material from a cement-bentonite matrix are investigated using three methods based on theoretical equations. These are: the diffusion equation for a plane source an equation for diffusion coupled to a first-order equation and an empirical method employing a polynomial equation. The results presented in this paper are from a 25-year mortar and concrete testing project that will influence the design choices for radioactive waste packaging for a future Serbian radioactive waste disposal center. Radioactive waste is waste material containing radioactive chemical elements which does not have a practical purpose. It is often the product of a nuclear process, such as nuclear fission. Waste can also be generated from the processing of fuel for nuclear reactors or nuclear weapons. The main objective in managing and disposing of radioactive (or other) waste is to protect people and the environment. This means isolating or diluting the waste so that the rate or concentration of any radionuclides returned to the biosphere is harmless. Storage as the placement of waste in a nuclear facility where isolation, environmental protection and human control are provided with the intent that the waste will be retrieved at a later time. Disposal as the emplacement of waste in an approved, specified facility (e.g. near surface or geological repository) without the intention of retrieval. The processing of radioactive wastes may be done for economic reasons (e.g. to reduce the volume for storage or disposal, or to recover a 'resource' from the waste), or safety reasons (e.g. converting the waste to a more 'stable' form, such as one that will contain the radionuclide inventory for a long time). Typically processing involves reducing

  14. Transport due to ion pressure gradient turbulence

    International Nuclear Information System (INIS)

    Connor, J.W.

    1986-01-01

    Turbulent transport due to the ion pressure gradient (or temperature drift) instability is thought to be significant when etasub(i)=d(ln Tsub(i))/d(ln n)>1. The invariance properties of the governing equations under scale transformations are used to discuss the characteristics of this turbulence. This approach not only clarifies the relationships between earlier treatments but also, in certain limits, completely determines the scaling properties of the fluctuations and the consequent thermal transport. (author)

  15. Numerical modelling of ion transport in flames

    KAUST Repository

    Han, Jie

    2015-10-20

    This paper presents a modelling framework to compute the diffusivity and mobility of ions in flames. The (n, 6, 4) interaction potential is adopted to model collisions between neutral and charged species. All required parameters in the potential are related to the polarizability of the species pair via semi-empirical formulas, which are derived using the most recently published data or best estimates. The resulting framework permits computation of the transport coefficients of any ion found in a hydrocarbon flame. The accuracy of the proposed method is evaluated by comparing its predictions with experimental data on the mobility of selected ions in single-component neutral gases. Based on this analysis, the value of a model constant available in the literature is modified in order to improve the model\\'s predictions. The newly determined ion transport coefficients are used as part of a previously developed numerical approach to compute the distribution of charged species in a freely propagating premixed lean CH4/O2 flame. Since a significant scatter of polarizability data exists in the literature, the effects of changes in polarizability on ion transport properties and the spatial distribution of ions in flames are explored. Our analysis shows that changes in polarizability propagate with decreasing effect from binary transport coefficients to species number densities. We conclude that the chosen polarizability value has a limited effect on the ion distribution in freely propagating flames. We expect that the modelling framework proposed here will benefit future efforts in modelling the effect of external voltages on flames. Supplemental data for this article can be accessed at http://dx.doi.org/10.1080/13647830.2015.1090018. © 2015 Taylor & Francis.

  16. Numerical simulation of the transport phenomena due to sudden heating in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Lei, S.Y.; Zheng, G.Y.; Wang, B.X.; Yang, R.G.; Xia, C.M.

    1997-07-01

    Such process as wet porous media suddenly heated by hot fluids frequently occurs in nature and in industrial applications. The three-variable simulation model was developed to predict violent transport phenomena due to sudden heating in porous media. Two sets of independent variables were applied to different regions in porous media in the simulation. For the wet zone, temperature, wet saturation and air pressure were used as the independent variables. For the dry zone, the independent variables were temperature, vapor pressure and air pressure. The model simulated two complicated transport processes in wet unsaturated porous media which is suddenly heated by melting metal or boiling water. The effect of the gas pressure is also investigated on the overall transport phenomena.

  17. Lattice Boltzmann modeling of transport phenomena in fuel cells and flow batteries

    Science.gov (United States)

    Xu, Ao; Shyy, Wei; Zhao, Tianshou

    2017-06-01

    Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.

  18. Spin-related transport phenomena in HgTe-based quantum well structures

    International Nuclear Information System (INIS)

    Koenig, Markus

    2007-12-01

    Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/Hg 0.3 Cd 0.7 Te quantum well structures. In our experiments, the existence of the quantum spin Hall (QSH) state was successfully demonstrated for the first time and the presented results provide clear evidence for the charge transport properties of the QSH state. Our experiments provide the first direct observation of the Aharonov-Casher (AC) effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSH relies on the peculiar band structure of the material and the existence of both the spin Hall effect and the AC effect is a consequence of the substantial spin-orbit interaction. (orig.)

  19. Spin-related transport phenomena in HgTe-based quantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Markus

    2007-12-15

    Within the scope of this thesis, spin related transport phenomena have been investigated in HgTe/Hg{sub 0.3}Cd{sub 0.7}Te quantum well structures. In our experiments, the existence of the quantum spin Hall (QSH) state was successfully demonstrated for the first time and the presented results provide clear evidence for the charge transport properties of the QSH state. Our experiments provide the first direct observation of the Aharonov-Casher (AC) effect in semiconductor structures. In conclusion, HgTe quantum well structures have proven to be an excellent template for studying spin-related transport phenomena: The QSH relies on the peculiar band structure of the material and the existence of both the spin Hall effect and the AC effect is a consequence of the substantial spin-orbit interaction. (orig.)

  20. Workshop on transport for a common ion driver

    International Nuclear Information System (INIS)

    Olson, C.C.; Lee, E.; Langdon, B.

    1994-01-01

    This report contains research in the following areas related to beam transport for a common ion driver: multi-gap acceleration; neutralization with electrons; gas neutralization; self-pinched transport; HIF and LIF transport, and relevance to common ion driver; LIF and HIF reactor concepts and relevance to common ion driver; atomic physics for common ion driver; code capabilities and needed improvement

  1. Influence of anomalous transport phenomena on onset of Neoclassical Tearing Modes in tokamaks

    International Nuclear Information System (INIS)

    Konovalov, S.V.; Mikhailovskii, A.B.; Shirokov, M.S.; Ozeki, T.; Takizuka, T.; Hayashi, N.

    2005-01-01

    Influence of anomalous perpendicular heat transport and anomalous ion perpendicular viscosity on conditions of Neoclassical Tearing Mode (NTM) onset is studied theoretically. Series of various parallel transport mechanisms competitive to anomalous cross-island heat transport in formation of the perturbed electron and ion temperature profiles within the island are considered. Analytical solutions to respective heat balance equations were found and perturbed temperature profiles were calculated rigorously. The partial contributions from the plasma electron and ion temperature perturbations in the bootstrap drive of the mode and magnetic curvature effect were then accounted in construction of a generalized transport threshold model of NTMs. Taking into account the curvature effect weakening in the generalized transport threshold model predicts notable improvement of NTM stability. The anomalous perpendicular ion viscosity was shown to modify collisionality dependence of polarization current effect reducing it to the low collisionality limit. The bootstrap drive of NTM in the presence of anomalous perpendicular ion viscosity was found to be dependent on the island rotation frequency and direction. For island rotating in direction of the electron diamagnetic drift viscosity effect was shown to be stabilizing. The role of viscosity effect grows rapidly with rise of the plasma ion temperature. (author)

  2. Chamber transport for heavy ion fusion

    International Nuclear Information System (INIS)

    Olson, Craig L.

    2014-01-01

    A brief review is given of research on chamber transport for HIF (heavy ion fusion) dating from the first HIF Workshop in 1976 to the present. Chamber transport modes are categorized into ballistic transport modes and channel-like modes. Four major HIF reactor studies are summarized (HIBALL-II, HYLIFE-II, Prometheus-H, OSIRIS), with emphasis on the chamber transport environment. In general, many beams are used to provide the required symmetry and to permit focusing to the required small spots. Target parameters are then discussed, with a summary of the individual heavy ion beam parameters required for HIF. The beam parameters are then classified as to their line charge density and perveance, with special emphasis on the perveance limits for radial space charge spreading, for the space charge limiting current, and for the magnetic (Alfven) limiting current. The major experiments on ballistic transport (SFFE, Sabre beamlets, GAMBLE II, NTX, NDCX) are summarized, with specific reference to the axial electron trapping limit for charge neutralization. The major experiments on channel-like transport (GAMBLE II channel, GAMBLE II self-pinch, LBNL channels, GSI channels) are discussed. The status of current research on HIF chamber transport is summarized, and the value of future NDCX-II transport experiments for the future of HIF is noted

  3. Center for Electrocatalysis, Transport Phenomena, and Materials (CETM) for Innovative Energy Storage - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Soloveichik, Grigorii [GE Global Research, Niskayuna, New York (United States)

    2015-11-30

    EFRC vision. The direct use of organic hydrides in fuel cells as virtual hydrogen carriers that generate stable organic molecules, protons, and electrons upon electro-oxidation and can be electrochemically charged by re-hydrogenating the oxidized carrier was the major focus of the Center for Electrocatalysis, Transport Phenomena and Materials for Innovative Energy Storage (EFRC-ETM). Compared to a hydrogen-on-demand design that includes thermal decomposition of organic hydrides in a catalytic reactor, the proposed approach is much simpler and does not require additional dehydrogenation catalysts or heat exchangers. Further, this approach utilizes the advantages of a flow battery (i.e., separation of power and energy, ease of transport and storage of liquid fuels) with fuels that have system energy densities similar to current hydrogen PEM fuel cells. EFRC challenges. Two major EFRC challenges were electrocatalysis and transport phenomena. The electrocatalysis challenge addresses fundamental processes which occur at a single molecular catalyst (microscopic level) and involve electron and proton transfer between the hydrogen rich and hydrogen depleted forms of organic liquid fuel and the catalyst. To form stable, non-radical dehydrogenation products from the organic liquid fuel, it is necessary to ensure fast transport of at least two electrons and two protons (per double bond formation). The same is true for the reverse hydrogenation reaction. The transport phenomena challenge addresses transport of electrons to/from the electrocatalyst and the current collector as well as protons across the polymer membrane. Additionally it addresses prevention of organic liquid fuel, water and oxygen transport through the PEM. In this challenge, the transport of protons or molecules involves multiple sites or a continuum (macroscopic level) and water serves as a proton conducting medium for the majority of known sulfonic acid based PEMs. Proton transfer in the presence of

  4. Final report, BWR drywell debris transport Phenomena Identification and Ranking Tables (PIRTs)

    International Nuclear Information System (INIS)

    Wilson, G.E.; Boyack, B.E.; Leonard, M.T.; Williams, K.A.; Wolf, L.T.

    1997-09-01

    The Nuclear Regulatory Commission has issued a Regulatory Bulletin and accompanying Regulatory Guide (1.82, Rev. 2) which requires licensees of boiling water reactors to develop a specific plan of action (including hardware backfits, if necessary) to preclude the possibility of early emergency core cooling system strainer blockage following a postulated loss-of-coolant-accident. The postulated mechanism for strainer blockage is destruction of piping insulation in the vicinity of the break and subsequent transport of fragmented insulation to the wetwell. In the absence of more definitive information, the Regulatory Guide recommends that licensees assume a drywell debris transport fraction of 1.0. Accordingly, the Nuclear Regulatory Commission initiated research focused toward developing a technical basis to provide insights useful to regulatory oversight of licensee submittals associated with resolution of the postulated strainer blockage issue. Part of this program was directed towards experimental and analytical research leading to a more realistic specification of the debris transport through the drywell to the wetwell. To help focus this development into a cost effective effort, a panel, with broad based knowledge and experience, was formed to address the relative importance of the various phenomena that can be expected in plant response to postulated accidents that may produce strainer blockage. The resulting phenomena identification and ranking tables reported herein were used to help guide research. The phenomena occurring in boiling water reactors drywells was the specific focus of the panel, although supporting experimental data and calculations of debris transport fractions were considered

  5. Transport phenomena in alkaline direct ethanol fuel cells for sustainable energy production

    Science.gov (United States)

    An, L.; Zhao, T. S.

    2017-02-01

    Alkaline direct ethanol fuel cells (DEFC), which convert the chemical energy stored in ethanol directly into electricity, are one of the most promising energy-conversion devices for portable, mobile and stationary power applications, primarily because this type of fuel cell runs on a carbon-neutral, sustainable fuel and the electrocatalytic and membrane materials that constitute the cell are relatively inexpensive. As a result, the alkaline DEFC technology has undergone a rapid progress over the last decade. This article provides a comprehensive review of transport phenomena of various species in this fuel cell system. The past investigations into how the design and structural parameters of membrane electrode assemblies and the operating parameters affect the fuel cell performance are discussed. In addition, future perspectives and challenges with regard to transport phenomena in this fuel cell system are also highlighted.

  6. Radiation transport phenomena and modeling. Part A: Codes; Part B: Applications with examples

    International Nuclear Information System (INIS)

    Lorence, L.J. Jr.; Beutler, D.E.

    1997-09-01

    This report contains the notes from the second session of the 1997 IEEE Nuclear and Space Radiation Effects Conference Short Course on Applying Computer Simulation Tools to Radiation Effects Problems. Part A discusses the physical phenomena modeled in radiation transport codes and various types of algorithmic implementations. Part B gives examples of how these codes can be used to design experiments whose results can be easily analyzed and describes how to calculate quantities of interest for electronic devices

  7. Ion transport in turbulent edge plasmas

    International Nuclear Information System (INIS)

    Helander, P.; Massachusetts Inst. of Tech., Cambridge, MA; Hazeltine, R.D.; Catto, P.J.

    1996-02-01

    Edge plasmas, such as the tokamak scrape-off layer, exist as a consequence of a balance between cross-field diffusion and parallel losses. The former is usually anomalous, and is widely thought to be driven by strong electrostatic turbulence. It is shown that the anomalous diffusion affects the parallel ion transport by giving rise to a new type of thermal force between different ion species. This force is parallel to the magnetic field, but arises entirely because of perpendicular gradients, and could be important for impurity retention in the tokamak divertor. (author)

  8. Review on modeling development for multiscale chemical reactions coupled transport phenomena in solid oxide fuel cells

    International Nuclear Information System (INIS)

    Andersson, Martin; Yuan, Jinliang; Sunden, Bengt

    2010-01-01

    A literature study is performed to compile the state-of-the-art, as well as future potential, in SOFC modeling. Principles behind various transport processes such as mass, heat, momentum and charge as well as for electrochemical and internal reforming reactions are described. A deeper investigation is made to find out potentials and challenges using a multiscale approach to model solid oxide fuel cells (SOFCs) and combine the accuracy at microscale with the calculation speed at macroscale to design SOFCs, based on a clear understanding of transport phenomena, chemical reactions and functional requirements. Suitable methods are studied to model SOFCs covering various length scales. Coupling methods between different approaches and length scales by multiscale models are outlined. Multiscale modeling increases the understanding for detailed transport phenomena, and can be used to make a correct decision on the specific design and control of operating conditions. It is expected that the development and production costs will be decreased and the energy efficiency be increased (reducing running cost) as the understanding of complex physical phenomena increases. It is concluded that the connection between numerical modeling and experiments is too rare and also that material parameters in most cases are valid only for standard materials and not for the actual SOFC component microstructures.

  9. Thermo-fluidic devices and materials inspired from mass and energy transport phenomena in biological system

    Institute of Scientific and Technical Information of China (English)

    Jian XIAO; Jing LIU

    2009-01-01

    Mass and energy transport consists of one of the most significant physiological processes in nature, which guarantees many amazing biological phenomena and activ-ities. Borrowing such idea, many state-of-the-art thermo-fluidic devices and materials such as artificial kidneys, carrier erythrocyte, blood substitutes and so on have been successfully invented. Besides, new emerging technologies are still being developed. This paper is dedicated to present-ing a relatively complete review of the typical devices and materials in clinical use inspired by biological mass and energy transport mechanisms. Particularly, these artificial thermo-fluidic devices and materials will be categorized into organ transplantation, drug delivery, nutrient transport, micro operation, and power supply. Potential approaches for innovating conventional technologies were discussed, corresponding biological phenomena and physical mechan-isms were interpreted, future promising mass-and-energy-transport-based bionic devices were suggested, and prospects along this direction were pointed out. It is expected that many artificial devices based on biological mass and energy transport principle will appear to better improve vari-ous fields related to human life in the near future.

  10. High-powered pulsed-ion-beam acceleration and transport

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, S. Jr.; Lockner, T.R.

    1981-11-01

    The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized.

  11. High-powered pulsed-ion-beam acceleration and transport

    International Nuclear Information System (INIS)

    Humphries, S. Jr.; Lockner, T.R.

    1981-11-01

    The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized

  12. Purinergic signalling in epithelial ion transport

    DEFF Research Database (Denmark)

    Novak, Ivana

    2011-01-01

    , including ion transport. In this review, I will first introduce the main components of the extracellular ATP signalling, which have become known as the purinergic signalling system. With more than 50 components or processes, just at cell membranes, it ranks as one of the most versatile signalling systems......-regulators of secretion. On an organ level, both receptor types can exert physiological functions and together with other partners in the purinergic signalling, integrated models for epithelial secretion and absorption are emerging....

  13. Hierarchical modeling of plasma and transport phenomena in a dielectric barrier discharge reactor

    Science.gov (United States)

    Bali, N.; Aggelopoulos, C. A.; Skouras, E. D.; Tsakiroglou, C. D.; Burganos, V. N.

    2017-12-01

    A novel dual-time hierarchical approach is developed to link the plasma process to macroscopic transport phenomena in the interior of a dielectric barrier discharge (DBD) reactor that has been used for soil remediation (Aggelopoulos et al 2016 Chem. Eng. J. 301 353-61). The generation of active species by plasma reactions is simulated at the microseconds (µs) timescale, whereas convection and thermal conduction are simulated at the macroscopic (minutes) timescale. This hierarchical model is implemented in order to investigate the influence of the plasma DBD process on the transport and reaction mechanisms during remediation of polluted soil. In the microscopic model, the variables of interest include the plasma-induced reactive concentrations, while in the macroscopic approach, the temperature distribution, and the velocity field both inside the discharge gap and within the polluted soil material as well. For the latter model, the Navier-Stokes and Darcy Brinkman equations for the transport phenomena in the porous domain are solved numerically using a FEM software. The effective medium theory is employed to provide estimates of the effective time-evolving and three-phase transport properties in the soil sample. Model predictions considering the temporal evolution of the plasma remediation process are presented and compared with corresponding experimental data.

  14. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39 (Iraq)

    2013-07-01

    Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport in micro PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize the micro fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a micro proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a micro PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

  15. Interfacial transport phenomena and stability in liquid-metal/water systems: scaling considerations

    International Nuclear Information System (INIS)

    Abdulla, S.; Liu, X.; Anderson, M.; Bonazza, R.; Corradini, M.; Cho, D.

    2001-01-01

    One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area give rise to very high heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. In this paper we describe current results from the first year of this research that studies the transport phenomena involved with the injection of water into molten metals (e.g., lead alloys). In particular, this work discusses scaling considerations related to direct contact heat exchange, our experimental plans for investigation and a test plan for the important experimental parameters; i.e., the water and liquid metal mass flow rates, the liquid metal pool temperature and the ambient pressure of the direct contact heat exchanger. Past experimental work and initial scaling results suggest that our experiments can directly represent the proper liquid metal pool temperature and the water subcooling. The experimental variation in water and liquid metal flow rates and system pressure (1-10 bar), although smaller than the current conceptual system designs, is sufficient to verify the expected scale effects to demonstrate the phenomena. (authors)

  16. A Novel Multi-Phase Stochastic Model for Lithium-Ion Batteries’ Degradation with Regeneration Phenomena

    Directory of Open Access Journals (Sweden)

    Jianxun Zhang

    2017-10-01

    Full Text Available A lithium-Ion battery is a typical degradation product, and its performance will deteriorate over time. In its degradation process, regeneration phenomena have been frequently encountered, which affect both the degradation state and rate. In this paper, we focus on how to build the degradation model and estimate the lifetime. Toward this end, we first propose a multi-phase stochastic degradation model with random jumps based on the Wiener process, where the multi-phase model and random jumps at the changing point are used to describe the variation of degradation rate and state caused by regeneration phenomena accordingly. Owing to the complex structure and random variables, the traditional Maximum Likelihood Estimation (MLE is not suitable for the proposed model. In this case, we treat these random variables as latent parameters, and then develop an approach for model identification based on expectation conditional maximum (ECM algorithm. Moreover, depending on the proposed model, how to estimate the lifetime with fixed changing point is presented via the time-space transformation technique, and the approximate analytical solution is derived. Finally, a numerical simulation and a practical case are provided for illustration.

  17. 78 FR 19024 - Lithium Ion Batteries in Transportation Public Forum

    Science.gov (United States)

    2013-03-28

    ... NATIONAL TRANSPORTATION SAFETY BOARD Lithium Ion Batteries in Transportation Public Forum On Thursday and Friday, April 11-12, 2013, the National Transportation Safety Board (NTSB) will convene a forum titled, ``Lithium Ion Batteries in Transportation.'' The forum will begin at 9:00 a.m. on both...

  18. THE IMPORTANCE OF LIMIT SOLUTIONS & TEMPORAL AND SPATIAL SCALES IN THE TEACHING OF TRANSPORT PHENOMENA

    Directory of Open Access Journals (Sweden)

    SÁVIO LEANDRO BERTOLI

    2016-07-01

    Full Text Available In the engineering courses the field of Transport Phenomena is of significant importance and it is in several disciplines relating to Fluid Mechanics, Heat and Mass Transfer. In these disciplines, problems involving these phenomena are mathematically formulated and analytical solutions are obtained whenever possible. The aim of this paper is to emphasize the possibility of extending aspects of the teaching-learning in this area by a method based on time scales and limit solutions. Thus, aspects relative to the phenomenology naturally arise during the definition of the scales and / or by determining the limit solutions. Aspects concerning the phenomenology of the limit problems are easily incorporated into the proposed development, which contributes significantly to the understanding of physics inherent in the mathematical modeling of each limiting case studied. Finally the study aims to disseminate the use of the limit solutions and of the time scales in the general fields of engineering.

  19. Characterization of transport phenomena in porous transport layers using X-ray microtomography

    Science.gov (United States)

    Hasanpour, S.; Hoorfar, M.; Phillion, A. B.

    2017-06-01

    Among different methods available for estimating the transport properties of porous transport layers (PTLs) of polymer electrolyte membrane fuel cells, X-ray micro computed tomography (X-μCT) imaging in combination with image-based numerical simulation has been recognized as a viable tool. In this study, four commercially-available single-layer and dual-layer PTLs are analyzed using this method in order to compare and contrast transport properties between different PTLs, as well as the variability within a single sheet. Complete transport property datasets are created for each PTL. The simulation predictions indicate that PTLs with high porosity show considerable variability in permeability and effective diffusivity, while PTLs with low porosity do not. Furthermore, it is seen that the Tomadakis-Sotirchos (TS) analytical expressions for porous media match the image-based simulations when porosity is relatively low but predict higher permeability and effective diffusivity for porosity values greater than 80%. Finally, the simulations show that cracks within MPL of dual-layer PTLs have a significant effect on the overall permeability and effective diffusivity of the PTLs. This must be considered when estimating the transport properties of dual-layer PTLs. These findings can be used to improve macro-scale models of product and reactant transport within fuel cells, and ultimately, fuel cell efficiency.

  20. Transportation of ions through cement based materials

    International Nuclear Information System (INIS)

    Chatterji, S.

    1994-01-01

    Transportation of ions, both anions and cations, through cement based materials is one of the important processes in their durability and as such has been studied very extensively. It has been studied from the point of view of the reinforcement corrosion, alkali-silica reaction, sulfate attack on cement and concrete, as well as in the context of the use of the cement based materials in the disposal of nuclear waste. In this paper the fundamental equations of diffusion, i.e. Fick's two equations, Nernst and Nernst-Planck equations have been collected. Attention has been drawn to the fact that Fick's two equations are valid for non-ionic diffusants and that for ions the relevant equations are those of Nernst and Nernst-Planck. The basic measurement techniques have also been commented upon

  1. Ion transport by the amphibian primary ureter

    DEFF Research Database (Denmark)

    Møbjerg, Nadja

    2008-01-01

    putative ion transport mechanisms in the primary ureter of the freshwater amphibian Ambystoma mexicanum (axolotl). Primary ureters isolated from axolotl larvae were perfused in vitro and single cells were impaled across the basal cell membrane with glass microelectrodes. In 42 cells the membrane potential......+] steps from 3 to 20 mmol/l and a hyperpolarization of Vm upon lowering [Na+] from 102 to 2 mmol/l, indicating the presence of luminal K+ and Na+ conductances. This study provides the first functional data on the vertebrate primary ureter. The data show that the primary ureter of axolotl larvae...

  2. Ion anomalous transport and feedback control. Final technical report, September 1, 1987 - August 31, 1997

    International Nuclear Information System (INIS)

    Sen, A.K.

    1998-01-01

    This final report is comprised of the following six progress reports: Ion Temperature Gradient Instability and Anomalous Transport, July 1989; Ion Temperature Gradient Instability and Anomalous Transport, August 1991; Ion Temperature Gradient Instability and Anomalous Transport, July 1993; Ion Anomalous Transport and Feedback Control, May 1994; Ion Anomalous Transport and Feedback Control, April 1995; and Ion Anomalous Transport and Feedback Control, December 1997

  3. Proceedings of the Fifth Microgravity Fluid Physics and Transport Phenomena Conference

    Science.gov (United States)

    Singh, Bhim S. (Editor)

    2000-01-01

    The Fifth Microgravity Fluid Physics and Transport Phenomena Conference provided the scientific community the opportunity to view the current scope of the Microgravity Fluid Physics and Transport Phenomena Program and research opportunities and plans for the near future. Consistent with the conference theme "Microgravity Research an Agency-Wide Asset" the conference focused not only on fundamental research but also on applications of this knowledge towards enabling future space exploration missions. The conference included 14 invited plenary talks, 61 technical paper presentations, 61 poster presentations, exhibits and a forum on emerging research themes focusing on nanotechnology and biofluid mechanics. This web-based proceeding includes the presentation and poster charts provided by the presenters of technical papers and posters that were scanned at the conference site. Abstracts of all the papers and posters are included and linked to the presentations charts. The invited and plenary speakers were not required to provide their charts and are generally not available for scanning and hence not posted. The conference program is also included.

  4. Frontiers in transport phenomena research and education: Energy systems, biological systems, security, information technology and nanotechnology

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, T.L.; Faghri, A. [Department of Mechanical Engineering, The University of Connecticut, Storrs, CT 06269-3139 (United States); Viskanta, R. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-2088 (United States)

    2008-09-15

    A US National Science Foundation-sponsored workshop entitled ''Frontiers in Transport Phenomena Research and Education: Energy Systems, Biological Systems, Security, Information Technology, and Nanotechnology'' was held in May of 2007 at the University of Connecticut. The workshop provided a venue for researchers, educators and policy-makers to identify frontier challenges and associated opportunities in heat and mass transfer. Approximately 300 invited participants from academia, business and government from the US and abroad attended. Based upon the final recommendations on the topical matter of the workshop, several trends become apparent. A strong interest in sustainable energy is evident. A continued need to understand the coupling between broad length (and time) scales persists, but the emerging need to better understand transport phenomena at the macro/mega scale has evolved. The need to develop new metrology techniques to collect and archive reliable property data persists. Societal sustainability received major attention in two of the reports. Matters involving innovation, entrepreneurship, and globalization of the engineering profession have emerged, and the responsibility to improve the technical literacy of the public-at-large is discussed. Integration of research thrusts and education activities is highlighted throughout. Specific recommendations, made by the panelists with input from the international heat transfer community and directed to the National Science Foundation, are included in several reports. (author)

  5. Heat and momentum transport of ion internal transport barrier plasmas on Large Helical Device

    International Nuclear Information System (INIS)

    Nagaoka, K.; Ida, K.; Yoshinuma, M.

    2010-11-01

    The peaked ion-temperature profile with steep gradient so called ion internal transport barrier (ion ITB) was formed in the neutral beam heated plasmas on the Large Helical Device (LHD) and the high-ion-temperature regime of helical plasmas has been significantly extended. The ion thermal diffusivity in the ion ITB plasma decreases down to the neoclassical transport level. The heavy ion beam probe (HIBP) observed the smooth potential profile with negative radial electric field (ion root) in the core region where the ion thermal diffusivity decreases significantly. The large toroidal rotation was also observed in the ion ITB core and the transport of toroidal momentum was analyzed qualitatively. The decrease of momentum diffusivity with ion temperature increase was observed in the ion ITB core. The toroidal rotation driven by ion temperature gradient so called intrinsic rotation is also identified. (author)

  6. The discovery of nuclear compression phenomena in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Schmidt, H.R.

    1991-01-01

    This article has attempted to review more than 15 years of research on shock compression phenomena, which is closely related to the goal of determining the nuclear EOS. Exciting progress has been made in this field over the last years and the fundamental physics of relativistic heavy ion-collisions has been well established. Overwhelming experimental evidence for the existence of shock compression has been extracted from the data. While early, inclusive measurements had been rather inconclusive, the advent of 4π-detectors like the GSI-LBL Plastic Ball had enabled the outstanding discovery of collective flow effects, as they were predicted by fluid-dynamical calculations. The particular case of conical Mach shock waves, anticipated for asymmetric collisions, has not been observed. What are the reasons? Surprisingly, the maximum energy of 2.1 GeV/nucleon for heavy ions at the BEVALAC had been found to be too low for Mach shock waves to occur. The small 20 Ne-nucleus is stopped in the heavy Au target. A Mach cone, however, if it had developed in the early stage of the collision will be wiped out by thermal motion in the process of slowing the projectile down to rest. A comparison of the data with models hints towards a rather hard EOS, although a soft one cannot be excluded definitively. A quantitative extraction is aggravated by a number in-medium and final-state effects which influence the calculated observables in a similar fashion as different choices of an EOS. Thus, as of now, the precise knowledge of the EOS of hot and dense matter is still an open question and needs further investigation. (orig.)

  7. Transport of Ions Across the Inner Envelope Membrane of Chloroplasts

    International Nuclear Information System (INIS)

    McCarty, R. E.

    2004-01-01

    The technical report outlines the results of nine years of research on how ions cross the inner envelope membrane of chloroplasts. The ions include protons, nitrite, calcium and ferrous iron. Bicarbonate transport was also studied

  8. Studies of local degradation phenomena in composite cathodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Kerlau, Marie; Marcinek, Marek; Srinivasan, Venkat; Kostecki, Robert M.

    2007-01-01

    LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 composite cathodes were cycled in model cells to study interfacial phenomena that could lead to electrode degradation. Ex situ spectroscopic analysis of the tested cathodes, which suffered substantial power and capacity loss, showed that the state of charge (SOC) of oxide particles on the cathode surface was highly non-uniform despite the deep discharge of the Li-ion cell at the end of the test. The inconsistent kinetic behavior of individual oxide particles was attributed to the degradation of electronic pathways within the composite cathodes. A simple theoretical model based on a distributed network showed that an increase of the contact resistance between composite electrode particles may be responsible for non-uniform local kinetic behavior of individual oxide particles and the overall degradation of electrochemical performance of composite electrodes

  9. Investigations of grain size dependent sediment transport phenomena on multiple scales

    Science.gov (United States)

    Thaxton, Christopher S.

    Sediment transport processes in coastal and fluvial environments resulting from disturbances such as urbanization, mining, agriculture, military operations, and climatic change have significant impact on local, regional, and global environments. Primarily, these impacts include the erosion and deposition of sediment, channel network modification, reduction in downstream water quality, and the delivery of chemical contaminants. The scale and spatial distribution of these effects are largely attributable to the size distribution of the sediment grains that become eligible for transport. An improved understanding of advective and diffusive grain-size dependent sediment transport phenomena will lead to the development of more accurate predictive models and more effective control measures. To this end, three studies were performed that investigated grain-size dependent sediment transport on three different scales. Discrete particle computer simulations of sheet flow bedload transport on the scale of 0.1--100 millimeters were performed on a heterogeneous population of grains of various grain sizes. The relative transport rates and diffusivities of grains under both oscillatory and uniform, steady flow conditions were quantified. These findings suggest that boundary layer formalisms should describe surface roughness through a representative grain size that is functionally dependent on the applied flow parameters. On the scale of 1--10m, experiments were performed to quantify the hydrodynamics and sediment capture efficiency of various baffles installed in a sediment retention pond, a commonly used sedimentation control measure in watershed applications. Analysis indicates that an optimum sediment capture effectiveness may be achieved based on baffle permeability, pond geometry and flow rate. Finally, on the scale of 10--1,000m, a distributed, bivariate watershed terain evolution module was developed within GRASS GIS. Simulation results for variable grain sizes and for

  10. Ion Transport by Ameloblasts during Amelogenesis.

    Science.gov (United States)

    Bronckers, A L J J

    2017-03-01

    Hypomineralization of developing enamel is associated with changes in ameloblast modulation during the maturation stage. Modulation (or pH cycling) involves the cyclic transformation of ruffle-ended (RE) ameloblasts facing slightly acidic enamel into smooth-ended (SE) ameloblasts near pH-neutral enamel. The mechanism of ameloblast modulation is not clear. Failure of ameloblasts of Cftr-null and anion exchanger 2 ( Ae2)-null mice to transport Cl - into enamel acidifies enamel, prevents modulation, and reduces mineralization. It suggests that pH regulation is critical for modulation and for completion of enamel mineralization. This report presents a review of the major types of transmembrane molecules that ameloblasts express to transport calcium to form crystals and bicarbonates to regulate pH. The type of transporter depends on the developmental stage. Modulation is proposed to be driven by the pH of enamel fluid and the compositional and/or physicochemical changes that result from increased acidity, which may turn RE ameloblasts into SE mode. Amelogenins delay outgrowth of crystals and keep the intercrystalline space open for diffusion of mineral ions into complete depth of enamel. Modulation enables stepwise removal of amelogenins from the crystal surface, their degradation, and removal from the enamel. Removal of matrix allows slow expansion of crystals. Modulation also reduces the stress that ameloblasts experience when exposed to high acid levels generated by mineral formation or by increased intracellular Ca 2+ . By cyclically interrupting Ca 2+ transport by RE ameloblasts and their transformation into SE ameloblasts, proton production ceases shortly and enables the ameloblasts to recover. Modulation also improves enamel crystal quality by selectively dissolving immature Ca 2+ -poor crystals, removing impurities as Mg 2+ and carbonates, and recrystallizing into more acid-resistant crystals.

  11. Microscopic Linear Response Theory of Spin Relaxation and Relativistic Transport Phenomena in Graphene

    Directory of Open Access Journals (Sweden)

    Manuel Offidani

    2018-05-01

    Full Text Available We present a unified theoretical framework for the study of spin dynamics and relativistic transport phenomena in disordered two-dimensional Dirac systems with pseudospin-spin coupling. The formalism is applied to the paradigmatic case of graphene with uniform Bychkov-Rashba interaction and shown to capture spin relaxation processes and associated charge-to-spin interconversion phenomena in response to generic external perturbations, including spin density fluctuations and electric fields. A controlled diagrammatic evaluation of the generalized spin susceptibility in the diffusive regime of weak spin-orbit interaction allows us to show that the spin and momentum lifetimes satisfy the standard Dyakonov-Perel relation for both weak (Gaussian and resonant (unitary nonmagnetic disorder. Finally, we demonstrate that the spin relaxation rate can be derived in the zero-frequency limit by exploiting the SU(2 covariant conservation laws for the spin observables. Our results set the stage for a fully quantum-mechanical description of spin relaxation in both pristine graphene samples with weak spin-orbit fields and in graphene heterostructures with enhanced spin-orbital effects currently attracting much attention.

  12. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    Energy Technology Data Exchange (ETDEWEB)

    M. Anderson; M. Corradini; K.Y. Bank; R. Bonazza; D. Cho

    2005-04-26

    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications.

  13. Fundamentals of Melt-Water Interfacial Transport Phenomena: Improved Understanding for Innovative Safety Technologies in ALWRs

    International Nuclear Information System (INIS)

    Anderson, M.; Corradini, M.; Bank, K.Y.; Bonazza, R.; Cho, D.

    2005-01-01

    The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of this work is to provide the fundamental understanding needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University in via test and analyses. We then address the appropriate scaling and design methodologies for reactor applications

  14. Modelling of melting and solidification transport phenomena during hypothetical NPP severe accidents

    International Nuclear Information System (INIS)

    Sarler, B.

    1992-01-01

    A physical and mathematical framework to deal with the transport phenomena occuring during melting and solidification of the hypothetical NPP severe accidents is presented. It concentrates on the transient temperature, velocity, and species concentration distributions during such events. The framework is based on the Mixture Continuum Formulation of the components and phases, cast in the boundary-domain integral shape structured by the fundamental solution of the Laplace equation. The formulation could cope with various solid-liquid sub-systems through the inclusion of the specific closure relations. The deduced system of boundary-domain integral equations for conservation of mass, energy, momentum, and species could be solved by the boundary element discrete approximative method. (author) [sl

  15. Transport phenomena and kinetic theory applications to gases, semiconductors, photons, and biological systems

    CERN Document Server

    Gabetta, Ester

    2007-01-01

    The study of kinetic equations related to gases, semiconductors, photons, traffic flow, and other systems has developed rapidly in recent years because of its role as a mathematical tool in many applications in areas such as engineering, meteorology, biology, chemistry, materials science, nanotechnology, and pharmacy. Written by leading specialists in their respective fields, this book presents an overview of recent developments in the field of mathematical kinetic theory with a focus on modeling complex systems, emphasizing both mathematical properties and their physical meaning. The overall presentation covers not only modeling aspects and qualitative analysis of mathematical problems, but also inverse problems, which lead to a detailed assessment of models in connection with their applications, and to computational problems, which lead to an effective link of models to the analysis of real-world systems. "Transport Phenomena and Kinetic Theory" is an excellent self-study reference for graduate students, re...

  16. Transport phenomena in high Tc superconductors. Resume of Ph.D thesis

    International Nuclear Information System (INIS)

    Crisan, I.A.

    1994-01-01

    This is an extended abstract of the Ph. D. thesis devoted to the transport phenomena in high-Tc superconductors. There are three chapters. The first chapter presents an overview of the essential theoretical aspects concerning the vortex dynamics particularly in ceramic superconductors. The chapter two gives a description of the preparation methods of superconductor samples used by the author as well as the measurement devices for volt-ampere characteristics and the associated electronic circuitry. In the third chapter there are presented the experimental data obtained from different samples prepared in different temperature and magnetic field conditions. The obtained results are finally interpreted in the frame of existent or original models. (M.I.C.). 31 Refs

  17. Numerical simulation of mass and energy transport phenomena in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Arpino, F. [Dipartimento di Meccanica, Strutture, Ambiente e Territorio (DiMSAT), University of Cassino, via Di Biasio 43, Cassino (Italy); Massarotti, N. [Dipertimento per le Tecnologie (DiT), University of Naples ' ' Parthenope' ' , Centro Direzionale, isola C4, 80143 Napoli (Italy)

    2009-12-15

    Solid Oxide Fuel Cells (SOFCs) represent a very promising technology for near future energy conversion thanks to a number of advantages, including the possibility of using different fuels. In this paper, a detailed numerical model, based on a general mathematical description and on a finite element Characteristic based Split (CBS) algorithm code is employed to simulate mass and energy transport phenomena in SOFCs. The model predicts the thermodynamic quantity of interest in the fuel cell. Full details of the numerical solution obtained are presented both in terms of heat and mass transfer in the cell and in terms of electro-chemical reactions that occur in the system considered. The results obtained with the present algorithm is compared with the experimental data available in the literature for validation, showing an excellent agreement. (author)

  18. Transport Phenomena in Porous Media Aspects of MicroMacro Behaviour

    CERN Document Server

    Ichikawa, Yasuaki

    2012-01-01

    This monograph presents an integrated perspective of the wide range of phenomena and processes applicable to the study of transport of species in porous materials. In order to formulate the entire range of porous media and their uses, this book gives the basics of continuum mechanics, thermodynamics, seepage and consolidation and diffusion, including multiscale homogenization methods. The particular structure of the book has been chosen because it is essential to be aware of the true properties of porous materials particularly in terms of nano, micro and macro mechanisms.  This book is of pedagogical and practical importance to the fields covered by civil, environmental, nuclear and petroleum engineering and also in chemical physics and geophysics as it relates to radioactive waste disposal, geotechnical engineering, mining and petroleum engineering and chemical engineering.

  19. Ab-initio calculations of the hydrogen-uranium system: Surface phenomena, absorption, transport and trapping

    International Nuclear Information System (INIS)

    Taylor, Christopher D.; Scott Lillard, R.

    2009-01-01

    Density functional theory was applied to the initial steps of uranium hydriding: surface phenomena, absorption, bulk transport and trapping. H adsorbs exothermically to the (0 0 1) surface, yet H absorption into the bulk is endothermic, with off-center octahedral absorption having the lowest absorption energy of 0.39 eV, relative to molecular H 2 . H absorption in interstitial sites causes a local softening of the bulk modulus. Diffusion of H in unstrained α-U has a barrier of 0.6 eV. The energy of H absorption adjacent to the chemical impurities C, S, Si was lowered by an amount proportional to the size of the impurity atom, and the resulting lattice strain Si > S > C. Thus, impurities may promote hydriding by providing surfaces or prestrained zones for H uptake.

  20. Energy-dispersed ions in the plasma sheet boundary layer and associated phenomena: Ion heating, electron acceleration, Alfvén waves, broadband waves, perpendicular electric field spikes, and auroral emissions

    Directory of Open Access Journals (Sweden)

    A. Keiling

    2006-10-01

    Full Text Available Recent Cluster studies reported properties of multiple energy-dispersed ion structures in the plasma sheet boundary layer (PSBL that showed substructure with several well separated ion beamlets, covering energies from 3 keV up to 100 keV (Keiling et al., 2004a, b. Here we report observations from two PSBL crossings, which show a number of identified one-to-one correlations between this beamlet substructure and several plasma-field characteristics: (a bimodal ion conics (<1 keV, (b field-aligned electron flow (<1 keV, (c perpendicular electric field spikes (~20 mV/m, (d broadband electrostatic ELF wave packets (<12.5 Hz, and (e enhanced broadband electromagnetic waves (<4 kHz. The one-to-one correlations strongly suggest that these phenomena were energetically driven by the ion beamlets, also noting that the energy flux of the ion beamlets was 1–2 orders of magnitude larger than, for example, the energy flux of the ion outflow. In addition, several more loosely associated correspondences were observed within the extended region containing the beamlets: (f electrostatic waves (BEN (up to 4 kHz, (g traveling and standing ULF Alfvén waves, (h field-aligned currents (FAC, and (i auroral emissions on conjugate magnetic field lines. Possible generation scenarios for these phenomena are discussed. In conclusion, it is argued that the free energy of magnetotail ion beamlets drove a variety of phenomena and that the spatial fine structure of the beamlets dictated the locations of where some of these phenomena occurred. This emphasizes the notion that PSBL ion beams are important for magnetosphere-ionosphere coupling. However, it is also shown that the dissipation of electromagnetic energy flux (at altitudes below Cluster of the simultaneously occurring Alfvén waves and FAC was larger (FAC being the largest than the dissipation of beam kinetic energy flux, and thus these two energy carriers contributed more to the energy transport on PSBL field lines

  1. Studies of the effect of radioactive waste on the transport phenomena in soil

    International Nuclear Information System (INIS)

    El-Reefy, A.I.A.F

    1992-01-01

    This thesis introduces a new concept in the field of soil mechanics. It is an integrated work between soil and radiation in the form of gamma-rays. Chapter II was introduced to cover the basics in geotechnical engineering so as to draw a clearer picture to radiologists. Similarly, Chapter III was introduced to enable geotechnical engineers to comprehend radioactive behaviour in general. Although these two chapters are for further reading they contain various points that will be referred to regularly in the latter pages. The aim of this work is to investigate: - The effect of γ -radiations on the transport phenomena in soil. This was carried out by studying the effect of the following factors on the transmission of γ -rays with different energies: 1) Soil sample thickness 2) Grain size 3)Water content 4) Degree of compaction. - The effect of γ -radiations on moisture movement through soil. -Using the -ray transmission method to determine the soil physical properties. - Improvement of soil to increase its ability to attenuate -radiations. Experimental work took place under strict conditions at the Hot Lab. Center located at Inchas. Soil sample was sought from a nearby site which eventually will be the actual radioactive disposal site. The physical properties of the soil sample were determined as well as its grain size distribution. Accurate and detailed data on the gamma rays transport phenomena in soils was obtained using an up to date γ -radiation measurement technique. Finally, the extensive data obtained throughout this research was recorded and analyzed to ultimately approach our aim

  2. Heat science and transport phenomena in fuel cells; Thermique et phenomenes de transport dans les piles a combustible

    Energy Technology Data Exchange (ETDEWEB)

    Liberatore, P.M.; Boillot, M. [Laboratoire des Sciences du Genie Chimique de Nancy, 54 - Vandoeuvre-les-Nancy (France); Bonnet, C.; Didieerjean, S.; Lapicque, F.; Deseure, J.; Lottin, O.; Maillet, D.; Oseen-Senda, J. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee, 54 - Vandoeuvre Les Nancy (France); Alexandre, A. [Laboratoire d' Etudes Thermiques, ENSMA, 86 Poitiers (France); Topin, F.; Occelli, R.; Daurelle, J.V. [IUSTI / Polytech' Marseille, Institut universitaire des Systemes Thermiques Industriels Ecole, 13 - Marseille (France); Pauchet, J.; Feidt, M. [CEA Grenoble, Groupement pour la recherche sur les echangeurs thermiques (Greth), 38 (France); Voarino, C. [CEA Centre d' Etudes du Ripault, 37 - Tours (France); Morel, B.; Laurentin, J.; Bultel, Y.; Lefebvre-Joud, F. [CEA Grenoble, LEPMI, 38 (France); Auvity, B.; Lasbet, Y.; Castelain, C.; Peerohossaini, H. [Ecole Centrale de Nantes, Laboratoire de Thermocinetique de Nantes (LTN), 44 - Nantes (France)

    2005-07-01

    In this work are gathered the transparencies of the lectures presented at the conference 'heat science and transport phenomena in fuel cells'. The different lectures have dealt with 1)the gas distribution in the bipolar plates of a fuel cell: experimental studies and computerized simulations 2)two-phase heat distributors in the PEMFC 3)a numerical study of the flow properties of the backing layers on the transfers in a PEMFC 4)modelling of the heat and mass transfers in a PEMFC 5)two-phase cooling of the PEMFC with pentane 6)stationary thermodynamic model of the SOFC in the GECOPAC system 7)modelling of the internal reforming at the anode of the SOFC 8)towards a new thermal design of the PEMFC bipolar plates. (O.M.)

  3. Colloids: a review of current knowledge with a view to application to phenomena of transportation within PWR

    International Nuclear Information System (INIS)

    Guinard, L.

    1996-01-01

    In an attempt to minimise dosimetry within the primary circuit of PWR units, research is being carried out into understanding the phenomena of transportation and deposition of corrosion products. It is therefore desirable to known the form of these corrosion products and the laws governing this form. It is generally considered that they are in soluble or particulate form. A third starts with a general presentation of colloids and goes on to define points which are useful, both on a theoretical and experimental level, in terms of application to phenomena of transportation within PWRs. (author). 69 refs., 30 figs., 6 tabs., 3 appends

  4. Investigation of Physical Phenomena and Cutting Efficiency for Laser Cutting on Anode for Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Dongkyoung Lee

    2018-02-01

    Full Text Available Lithium-ion batteries have a higher energy density than other secondary batteries. Among the lithium-ion battery manufacturing process, electrode cutting is one of the most important processes since poor cut quality leads to performance degradation, separator protrusion, and local electric stress concentration. This may, eventually, lead to malfunction of lithium-ion batteries or explosion. The current mechanical cutting technology uses a contact process and this may lead to process instability. Furthermore, there are additional costs if the tools and cell design are changed. To solve these issues, laser cutting has been used. Conventional dependent parameters have limitations in investigating and explaining many physical phenomena during the laser cutting of electrodes. Therefore, this study proposes specific widths such as melting, top, and kerf width. Moreover, the relationship between laser parameters and multiphysical phenomena with the proposed widths are investigated. Five types of classification with regard to physical phenomena are presented and explained with SEM images. Cutting efficiency is estimated with the proposed widths. The proposed specific cutting widths, five types of geometrical classification, and cutting efficiency can be used as standardized parameters to evaluate the cutting quality.

  5. Numerical Simulation of Ion Transport in a Nano-Electrospray Ion Source at Atmospheric Pressure

    Science.gov (United States)

    Wang, Wei; Bajic, Steve; John, Benzi; Emerson, David R.

    2018-03-01

    Understanding ion transport properties from the ion source to the mass spectrometer (MS) is essential for optimizing device performance. Numerical simulation helps in understanding of ion transport properties and, furthermore, facilitates instrument design. In contrast to previously reported numerical studies, ion transport simulations in a continuous injection mode whilst considering realistic space-charge effects have been carried out. The flow field was solved using Reynolds-averaged Navier-Stokes (RANS) equations, and a particle-in-cell (PIC) method was applied to solve a time-dependent electric field with local charge density. A series of ion transport simulations were carried out at different cone gas flow rates, ion source currents, and capillary voltages. A force evaluation analysis reveals that the electric force, the drag force, and the Brownian force are the three dominant forces acting on the ions. Both the experimental and simulation results indicate that cone gas flow rates of ≤250 slph (standard liter per hour) are important for high ion transmission efficiency, as higher cone gas flow rates reduce the ion signal significantly. The simulation results also show that the ion transmission efficiency reduces exponentially with an increased ion source current. Additionally, the ion loss due to space-charge effects has been found to be predominant at a higher ion source current, a lower capillary voltage, and a stronger cone gas counterflow. The interaction of the ion driving force, ion opposing force, and ion dispersion is discussed to illustrate ion transport mechanism in the ion source at atmospheric pressure. [Figure not available: see fulltext.

  6. δf simulation of ion neoclassical transport

    International Nuclear Information System (INIS)

    Wang, W.; Nakajima, N.; Okamoto, M.; Murakami, S.

    1999-07-01

    Ion neoclassical transport with finite orbit width dynamics is calculated over whole poloidal cross section by using accurate δf method which employs an improved like-particle collision operator and an accurate weighting scheme to solve drift kinetic equation. Ion thermal transport near magnetic axis shows a great reduction from its conventional neoclassical level due to non-standard orbit topology, like that of previous δf simulation. On other hand, the direct particle loss from confinement region may strongly increase ion energy transport near the edge. It is found that ion parallel flow near the axis is also largely reduced due to non-standard orbit topology. In the presence of steep density gradient, ion thermal conductivity is significantly reduced, and an ion particle flux is driven by self-collision alone. (author)

  7. Investigation of high-p{sub T} phenomena within a partonic transport model

    Energy Technology Data Exchange (ETDEWEB)

    Fochler, Oliver

    2011-10-26

    In the work presented herein the microscopic transport model BAMPS (Boltzmann Approach to Multi-Parton Scatterings) is applied to simulate the time evolution of the hot partonic medium that is created in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in Pb+Pb collisions at the recently started Large Hadron Collider (LHC). The study is especially focused on the investigation of the nuclear modification factor R{sub AA}, that quantifies the suppression of particle yields at large transverse momentum with respect to a scaled proton+proton reference, and the simultaneous description of the collective properties of the medium in terms of the elliptic flow v{sub 2} within a common framework. (orig.)

  8. Investigation of high-pT phenomena within a partonic transport model

    International Nuclear Information System (INIS)

    Fochler, Oliver

    2011-01-01

    In the work presented herein the microscopic transport model BAMPS (Boltzmann Approach to Multi-Parton Scatterings) is applied to simulate the time evolution of the hot partonic medium that is created in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in Pb+Pb collisions at the recently started Large Hadron Collider (LHC). The study is especially focused on the investigation of the nuclear modification factor R AA , that quantifies the suppression of particle yields at large transverse momentum with respect to a scaled proton+proton reference, and the simultaneous description of the collective properties of the medium in terms of the elliptic flow v 2 within a common framework. (orig.)

  9. Mass transport and chloride ion complexes in occluded cell

    International Nuclear Information System (INIS)

    Tsuru, T.; Hashimoto, K.; Nishikata, A.; Haruyama, S.

    1989-01-01

    Changes in the transport and the concentration of ions in a model occluded cell are traced during galvanostatic anodic polarization of a mild steel and a stainless steel. Apparent transport numbers of anions and cations, which were estimated from chemical analysis of solution, were different from those calculated from known mobility data. At the initial stage of the polarization, the transport number of chloride ion was almost unity, and then decreased gradually. For the mild steel, the concentration of total chloride ion accumulated in the occluded compartment increased with the anodic charge passed, and the amount of chloride ion complexed with cations also increased. The chloride complex was estimated as FeCl + . For SUS304 stainless steel, the total chloride ion increased, however, the free chloride ion, which responded to an Ag/AgCl electrode remained approximately 2 mol/dm 3 . Therefore, most of the chloride ions transferred into the occluded cell formed complex ions, such as CrCl n 3-n . The number of chloride ion coordinated to ferrous and chromic ions was estimated from the data fo mass transport for the case of the mild steel and the stainless steel. (author) 9 refs., 14 figs

  10. Modeling diffusion-governed solidification of ternary alloys - Part 2: Macroscopic transport phenomena and macrosegregation.

    Science.gov (United States)

    Wu, M; Li, J; Ludwig, A; Kharicha, A

    2014-09-01

    Part 1 of this two-part investigation presented a multiphase solidification model incorporating the finite diffusion kinetics and ternary phase diagram with the macroscopic transport phenomena (Wu et al., 2013). In Part 2, the importance of proper treatment of the finite diffusion kinetics in the calculation of macrosegregation is addressed. Calculations for a two-dimensional (2D) square casting (50 × 50 mm 2 ) of Fe-0.45 wt.%C-1.06 wt.%Mn considering thermo-solutal convection and crystal sedimentation are performed. The modeling result indicates that the infinite liquid mixing kinetics as assumed by classical models (e.g., the Gulliver-Scheil or lever rule), which cannot properly consider the solute enrichment of the interdendritic or inter-granular melt at the early stage of solidification, might lead to an erroneous estimation of the macrosegregation. To confirm this statement, further theoretical and experimental evaluations are desired. The pattern and intensity of the flow and crystal sedimentation are dependent on the crystal morphologies (columnar or equiaxed); hence, the potential error of the calculated macrosegregation caused by the assumed growth kinetics depends on the crystal morphology. Finally, an illustrative simulation of an engineering 2.45-ton steel ingot is performed, and the results are compared with experimental results. This example demonstrates the model applicability for engineering castings regarding both the calculation efficiency and functionality.

  11. Study of phenomena of tracer transport and dispersion in fractured media

    International Nuclear Information System (INIS)

    Ippolito, Irene

    1993-01-01

    The objective of this research thesis is to present some transport phenomena according to two different approaches: firstly, the study of flows and tracing in a natural crack within a granitic site, and secondly, the study of flows of different geometries in model cracks, mainly by using techniques of tracer dispersion. The author first presents some properties of fractured media and elements of the theory of the phenomenon of dispersion. She notably discusses the reversibility of the Taylor dispersion which is the prevailing mechanism for simply connected geometries such as in the case of a flow between two continuous solid surfaces limiting a fracture. In the next chapters, the author reports the analysis of characteristics of local structures (mouths, roughnesses) of a single fracture by using echo dispersion. She reports experiments as well as Monte Carlo simulations performed on well defined geometries. In a parallel way, some characteristics measurements (rate-pressure, distribution of flows and tracing in transmission) and mechanical measurements of fracture deformation have been performed on a natural fracture in a granitic site [fr

  12. The application of the Chebyshev-spectral method in transport phenomena

    CERN Document Server

    Guo, Weidong; Narayanan, Ranga

    2012-01-01

    Transport phenomena problems that occur in engineering and physics are often multi-dimensional and multi-phase in character.  When taking recourse to numerical methods the spectral method is particularly useful and efficient. The book is meant principally to train students and non-specialists  to use the spectral method for solving problems that model fluid flow in closed geometries with heat or mass transfer.  To this aim the reader should bring a working knowledge of fluid mechanics and heat transfer and should be readily conversant with simple concepts of linear algebra including spectral decomposition of matrices as well as solvability conditions for inhomogeneous problems.  The book is neither meant to supply a ready-to-use program that is all-purpose nor to go through all manners of mathematical proofs.  The focus in this tutorial is on the use of the spectral methods for space discretization, because this is where most of the difficulty lies. While time dependent problems are also of great interes...

  13. Magneto-transport phenomena in metal/SiO2/n(p)-Si hybrid structures

    Science.gov (United States)

    Volkov, N. V.; Tarasov, A. S.; Rautskii, M. V.; Lukyanenko, A. V.; Bondarev, I. A.; Varnakov, S. N.; Ovchinnikov, S. G.

    2018-04-01

    Present review touches upon a subject of magnetotransport phenomena in hybrid structures which consist of ferromagnetic or nonmagnetic metal layer, layer of silicon oxide and silicon substrate with n- or p-type conductivity. Main attention will be paid to a number gigantic magnetotransport effects discovered in the devices fabricated on the base of the M/SiO2/n(p)-Si (M is ferromagnetic or paramagnetic metal) hybrid structures. These effects include bias induced dc magnetoresistance, gigantic magnetoimpedance, dc magnetoresistance induced by an optical irradiation and lateral magneto-photo-voltaic effect. The magnetoresistance ratio in ac and dc modes for some of our devices can exceed 106% in a magnetic field below 1 T. For lateral magneto-photo-voltaic effect, the relative change of photo-voltage in magnetic field can reach 103% at low temperature. Two types of mechanisms are responsible for sensitivity of the transport properties of the silicon based hybrid structures to magnetic field. One is related to transformation of the energy structure of the (donor) acceptor states including states near SiO2/n(p)-Si interface in magnetic field. Other mechanism is caused by the Lorentz force action. The features in behaviour of magnetotransport effects in concrete device depend on composition of the used structure, device topology and experimental conditions (bias voltage, optical radiation and others). Obtained results can be base for design of some electronic devices driven by a magnetic field. They can also provide an enhancement of the functionality for existing sensors.

  14. Modelling of melting and solidification transport phenomena during hypothetical NPP severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sarler, B [Inst. Jozef Stefan, Ljubljana (Slovenia)

    1992-07-01

    A physical and mathematical framework to deal with the transport phenomena occuring during melting and solidification of the hypothetical NPP severe accidents is presented. It concentrates on the transient temperature, velocity, and species concentration distributions during such events. The framework is based on the Mixture Continuum Formulation of the components and phases, cast in the boundary-domain integral shape structured by the fundamental solution of the Laplace equation. The formulation could cope with various solid-liquid sub-systems through the inclusion of the specific closure relations. The deduced system of boundary-domain integral equations for conservation of mass, energy, momentum, and species could be solved by the boundary element discrete approximative method. (author) [Slovenian] Predstavljeno je fizikalno in matematicno ogrodje za obravnavo prenosnih pojavov taljenja in strjevanja med hipoteticnimi tezkimi nezgodami v jedrskih elektrarnah. Osredotoceno je na popis neustaljene porazdelitve temperatur, hitrosti in koncentracij sestavin med taksnimi dogodki. Ogrodje temelji na formulaciji kontinuuma mesanice komponent in faz, v obliki robno obmocnih integralskih enacb, ki so sestavljena na podlagi fundamentalne resitve Laplace-ove enacbe. Formulacija lahko popisuje stevilne trdno-tekoce pod-sisteme na podlagi specificnih sklopitvenih relacij. Izpeljan sistem robno-obmocnih integralskih enacb za popis ohranitve mase, energije, gibalne kolicine in sestavin lahko resimo na podlagi diskretne aproksimativne metode robnih elementov. (author)

  15. Transport Phenomena Projects: Natural Convection between Porous, Concentric Cylinders--A Method to Learn and to Innovate

    Science.gov (United States)

    Saatadjian, Esteban; Lesage, Francois; Mota, Jose Paulo B.

    2013-01-01

    A project that involves the numerical simulation of transport phenomena is an excellent method to teach this subject to senior/graduate chemical engineering students. The subject presented here has been used in our senior/graduate course, it concerns the study of natural convection heat transfer between two concentric, horizontal, saturated porous…

  16. Vacuum system control for the Heavy Ion Transport Line

    International Nuclear Information System (INIS)

    Stattel, P.; Feigenbaum, I.; Hseuh, H.C.; Robinson, T.; Skelton, R.; Wong, V.

    1987-01-01

    The Brookhaven AGS, 807 m in circumference, and the Tandem Van de Graaff are now joined together by a transport line, 600 m in length. This now allows heavy ions from the Tandem, up to fully stripped sulfur (M = 32) to be transported into the AGS and accelerated to 15 GeV/A. With the addition of a booster between the Tandem and the AGS in the near future, heavy ions such as gold (M = 200) can be accelerated to 30 Z/A GeV/A. This paper describes the HITL (Heavy Ion Transport Line) vacuum control system design and implementation

  17. A Rest Time-Based Prognostic Framework for State of Health Estimation of Lithium-Ion Batteries with Regeneration Phenomena

    Directory of Open Access Journals (Sweden)

    Taichun Qin

    2016-11-01

    Full Text Available State of health (SOH prognostics is significant for safe and reliable usage of lithium-ion batteries. To accurately predict regeneration phenomena and improve long-term prediction performance of battery SOH, this paper proposes a rest time-based prognostic framework (RTPF in which the beginning time interval of two adjacent cycles is adopted to reflect the rest time. In this framework, SOH values of regeneration cycles, the number of cycles in regeneration regions and global degradation trends are extracted from raw SOH time series and predicted respectively, and then the three sets of prediction results are integrated to calculate the final overall SOH prediction values. Regeneration phenomena can be found by support vector machine and hyperplane shift (SVM-HS model by detecting long beginning time intervals. Gaussian process (GP model is utilized to predict the global degradation trend, and nonlinear models are utilized to predict the regeneration amplitude and the cycle number of each regeneration region. The proposed framework is validated through experimental data from the degradation tests of lithium-ion batteries. The results demonstrate that both the global degradation trend and the regeneration phenomena of the testing batteries can be well predicted. Moreover, compared with the published methods, more accurate SOH prediction results can be obtained under this framework.

  18. Peculiarities of the radioactive particles transport phenomena in the facilitated diffusion processes

    International Nuclear Information System (INIS)

    Gavryushenko, D.A.; Sisojev, V.M.; Cherevko, K.V.; Vlasenko, T.S.

    2017-01-01

    The work is devoted to the up to date problem that is the description of the radioactive particle diffusion processes. One of the aims of the present study is to estimate the effects caused by the irradiation of the liquid systems on the ongoing transport processes. That can allow predicting the behavior of the liquid systems in the presence of the radioactive sources. The main objective of the present work is studying the radioactive particles diffusion phenomena with the possible facilitated diffusion processes being considered. The phenomena are studied based on the fundamental relations of the nonequilibrium statistical thermodynamics. The diffusive flows are evaluated with the special attention given to the accounting of the entropy effects due to the appearance of the new radioactive particles in the system. The developed approach is used to estimate the diffusive flow of the radioactive particles for the case of the plane-parallel pore with the semi-transparent walls. The choice of a model can be justified as it might be used to describe the production of the radioactive contaminated water when the radionuclide face the diffusion process after being washed from the radioactive wastes and the rests of the nuclear fuel. Within the suggested model it is shown that the diffusion coefficient depends on the structural properties of the liquid systems that might be changed under the influence of the irradiation. The obtained equations for calculating the diffusive flows show the definite stabilizing effect in respect to the concentration difference in between the boundaries of the plane-parallel pore. It leads to the decreased changes of the diffusive flow when the concentrations of the radioactive particles at the boundaries are changed in comparison with those observed for the constant diffusion coefficient. The observed behavior for the ideal solution model is explained by the entropy effects. The qualitative analysis of the possible influence of the changes in

  19. Phenomena accompanying gradient-B drift injection of energetic ions into Tokamak plasmas

    International Nuclear Information System (INIS)

    Goldston, R.J.; Jassby, D.L.

    1976-01-01

    The application of vertically asymmetric toroidal-field ripple, in order to permit the gradient B-drift injection and subsequent capture of energetic ions, results in a new radial diffusion of banana orbits. The nearly mono-kinetic velocity distribution of gradient B-drifting ions in the outer plasma region represents a large source of free energy; and the nonambipolar inward drift of these ions modifies the radial electric field

  20. Recent applications of the Boltzmann master equation to heavy ion precompound decay phenomena

    International Nuclear Information System (INIS)

    Blann, M.; Remington, B.A.

    1988-06-01

    The Boltzmann master equation (BME) is described and used as a tool to interpret preequilibrium neutron emission from heavy ion collisions gated on evaporation residue or fission fragments. The same approach is used to interpret neutron spectra gated on deep inelastic and quasi-elastic heavy ion collisions. Less successful applications of BME to proton inclusive data with 40 MeV/u incident 12 C ions are presented, and improvements required in the exciton injection term are discussed

  1. Mathematical Model of Ion Transport in Electrodialysis Process

    Directory of Open Access Journals (Sweden)

    F.S. Rohman

    2010-10-01

    Full Text Available Mathematical models of ion transport in electrodialysis process is reviewed and their basics concept is discussed. Three scales of ion transport reviewed are: 1 ion transport in the membrane, where two approaches are used, the irreversible thermodynamics and modeling of the membrane material; 2 ion transport in a three-layer system composed of a membrane with two adjoining diffusion layers; and 3 coupling with hydraulic flow system in an electrodialysis 2D and 3D cell, where the differential equation of convectivediffusion is used. Most of the work carried out in the past implemented NP equations since relatively easily coupled with other equations describing hydrodynamic conditions and ion transport in the surrounding solutions, chemical reactions in the solutions and the membrane, boundary and other conditions. However, it is limited to point ionic transport in homogenous and uniformly - grainy phases of structure. © 2008 BCREC UNDIP. All rights reserved.[Received: 21 January 2008, Accepted: 10 March 2008][How to Cite: F.S. Rohman, N. Aziz (2008. Mathematical Model of Ion Transport in Electrodialysis Process. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 3-8. doi:10.9767/bcrec.3.1-3.7122.3-8][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.3.1-3.7122.3-8 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7122 ] 

  2. Transport theory of dissipative heavy-ion collisions

    International Nuclear Information System (INIS)

    Norenberg, W.

    1979-01-01

    The lectures present the formulation of a transport theory, the derivation of a practicable transport equation (Fokker-Planck equation) and the evaluation of transport coefficients for dissipative (or deeply inelastic) heavy-ion collisions. The applicability of the theoretical concept is tested with remarkable success in the analyses of various experimental information (mass transfer, angular-momentum dissipation and energy loss). Some critical remarks on the present situation of transport theories are added. Future developments are outlined. (author)

  3. Fast ions and momentum transport in JET tokamak plasmas

    International Nuclear Information System (INIS)

    Salmi, A.

    2012-01-01

    Fast ions are an inseparable part of fusion plasmas. They can be generated using electromagnetic waves or injected into plasmas as neutrals to heat the bulk plasma and to drive toroidal rotation and current. In future power plants fusion born fast ions deliver the main heating into the plasma. Understanding and controlling the fast ions is of crucial importance for the operation of a power plant. Furthermore, fast ions provide ways to probe the properties of the thermal plasma and get insight of its confinement properties. In this thesis, numerical code packages are used and developed to simulate JET experiments for a range of physics issues related to fast ions. Namely, the clamping fast ion distribution at high energies with RF heating, fast ion ripple torque generation and the toroidal momentum transport properties using NBI modulation technique are investigated. Through a comparison of numerical simulations and the JET experimental data it is shown that the finite Larmor radius effects in ion cyclotron resonance heating are important and that they can prevent fast ion tail formation beyond certain energy. The identified mechanism could be used for tailoring the fast ion distribution in future experiments. Secondly, ASCOT simulations of NBI ions in a ripple field showed that most of the reduction of the toroidal rotation that has been observed in the JET enhanced ripple experiments could be attributed to fast ion ripple torque. Finally, fast ion torque calculations together with momentum transport analysis have led to the conclusion that momentum transport in not purely diffusive but that a convective component, which increases monotonically in radius, exists in a wide range of JET plasmas. Using parameter scans, the convective transport has been shown to be insensitive to collisionality and q-profile but to increase strongly against density gradient. (orig.)

  4. Fast ions and momentum transport in JET tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Salmi, A.

    2012-07-01

    Fast ions are an inseparable part of fusion plasmas. They can be generated using electromagnetic waves or injected into plasmas as neutrals to heat the bulk plasma and to drive toroidal rotation and current. In future power plants fusion born fast ions deliver the main heating into the plasma. Understanding and controlling the fast ions is of crucial importance for the operation of a power plant. Furthermore, fast ions provide ways to probe the properties of the thermal plasma and get insight of its confinement properties. In this thesis, numerical code packages are used and developed to simulate JET experiments for a range of physics issues related to fast ions. Namely, the clamping fast ion distribution at high energies with RF heating, fast ion ripple torque generation and the toroidal momentum transport properties using NBI modulation technique are investigated. Through a comparison of numerical simulations and the JET experimental data it is shown that the finite Larmor radius effects in ion cyclotron resonance heating are important and that they can prevent fast ion tail formation beyond certain energy. The identified mechanism could be used for tailoring the fast ion distribution in future experiments. Secondly, ASCOT simulations of NBI ions in a ripple field showed that most of the reduction of the toroidal rotation that has been observed in the JET enhanced ripple experiments could be attributed to fast ion ripple torque. Finally, fast ion torque calculations together with momentum transport analysis have led to the conclusion that momentum transport in not purely diffusive but that a convective component, which increases monotonically in radius, exists in a wide range of JET plasmas. Using parameter scans, the convective transport has been shown to be insensitive to collisionality and q-profile but to increase strongly against density gradient. (orig.)

  5. Transport of heavy ions through matter within ion optical systems

    International Nuclear Information System (INIS)

    Schwab, T.

    1991-04-01

    In this thesis for the first time higher-order ion-optical calculations were connected with the whole phase-space changes of the heavy ions in passing through matter. With the developed programs and the newly proposed analytical methods atomic and nuclear interactions of the heavy ions within ion optical systems can be described realistically. The results of this thesis were applied to the conception of the fragment separator (FRS) and to the planning and preparation of experiments at the new GSI accelerator facility. Especially for the description of the ion-optical combination of FRS and the storage ring ESR the developed programs and methods proved to be necessary. A part of the applied theories on the atomic stopping could be confirmed in the framework of this thesis in an experiment with the high-resolving spectrometer SPEC at GANIL. The method of the isotopically pure separation of projectile fragments by means of magnetic analysis and the electronic energy loss could be also experimentally successfully tested at several energies (60-400 MeV/u). Furthermore in this thesis also application-related problems regarding a tumor therapy with heavy ions were solved. A concept for a medical separator (BMS) was developed, which separates light diagnosis beams isotopically purely and beyond improves the energy sharpness by means of an especially shaped (monoenergetic) stopper so that an in-situ range determination is possible with an accuracy of about one millimeter. (orig./HSI) [de

  6. Neutralization principles for the Extraction and Transport of Ion Beams

    CERN Document Server

    Riege, H

    2000-01-01

    The strict application of conventional extraction techniques of ion beams from a plasma source is characterized by a natural intensity limit determined by space charge.The extracted current may be enhanced far beyond this limit by neutralizing the space charge of the extracted ions in the first extraction gap of the source with electrons injected from the opposite side. The transverse and longitudinal emittances of a neutralized ion beam, hence its brightness, are preserved. Results of beam compensation experiments, which have been carried out with a laser ion source, are resumed for proposing a general scheme of neutralizing ion sources and their adjacent low-energy beam transport channels with electron beams. Many technical applications of high-mass ion beam neutralization technology may be identified: the enhancement of ion source output for injection into high-intensity, low-and high-energy accelerators, or ion thrusters in space technology, for the neutral beams needed for plasma heating of magnetic conf...

  7. Structure, Ion Transport, and Rheology of Nanoparticle Salts

    KAUST Repository

    Wen, Yu Ho; Lu, Yingying; Dobosz, Kerianne M.; Archer, Lynden A.

    2014-01-01

    particles into medium and high dielectric constant liquids yields electrolytes with unique structure and transport properties. We find that electrostatic repulsion imparted by ion dissociation can be tuned to control the dispersion state and rheology through

  8. Transport due to ion temperature gradient mode vortex turbulence

    International Nuclear Information System (INIS)

    Pavlenko, V.P.; Weiland, J.

    1991-01-01

    The ion energy transport due to an ensemble of nonlinear vortices is calculated in the test particle approximation for a strongly turbulent plasma. A diffusion coefficient proportional to the root of the stationary turbulence level is obtained. (au)

  9. A new approach for understanding ion transport in glasses; example ...

    Indian Academy of Sciences (India)

    †Department of Physics, Government College for Women, Chintamani 563 125, India .... Our attention here is focused on understanding how ion transport takes ...... Almond D P, West A R and Grant R J 1982 Solid State Commun. 44. 1277.

  10. Ion sampling and transport in Inductively Coupled Plasma Mass Spectrometry

    Science.gov (United States)

    Farnsworth, Paul B.; Spencer, Ross L.

    2017-08-01

    Quantitative accuracy and high sensitivity in inductively coupled plasma mass spectrometry (ICP-MS) depend on consistent and efficient extraction and transport of analyte ions from an inductively coupled plasma to a mass analyzer, where they are sorted and detected. In this review we examine the fundamental physical processes that control ion sampling and transport in ICP-MS and compare the results of theory and computerized models with experimental efforts to characterize the flow of ions through plasma mass spectrometers' vacuum interfaces. We trace the flow of ions from their generation in the plasma, into the sampling cone, through the supersonic expansion in the first vacuum stage, through the skimmer, and into the ion optics that deliver the ions to the mass analyzer. At each stage we consider idealized behavior and departures from ideal behavior that affect the performance of ICP-MS as an analytical tool.

  11. Simulation of Chamber Transport for Heavy-Ion-Fusion Drivers

    International Nuclear Information System (INIS)

    Sharp, W.M.; Callahan, D.A.; Tabak, M.; Yu, S.S.; Peterson, P.F.; Rose, D.V.; Welch, D.R.

    2003-01-01

    The heavy-ion fusion (HIF) community recently developed a power-plant design that meets the various requirements of accelerators, final focus, chamber transport, and targets. The point design is intended to minimize physics risk and is certainly not optimal for the cost of electricity. Recent chamber-transport simulations, however, indicate that changes in the beam ion species, the convergence angle, and the emittance might allow more-economical designs

  12. SIMULATION OF CHAMBER TRANSPORT FOR HEAVY-ION FUSION DRIVERS

    International Nuclear Information System (INIS)

    Sharp, W M; Callahan, D A; Tabak, M; Yu, S S; Peterson, P F; Rose, D V; Welch, D R

    2004-01-01

    The heavy-ion fusion (HIF) community recently developed a power-plant design that meets the various requirements of accelerators, final focus, chamber transport, and targets. The point design is intended to minimize physics risk and is certainly not optimal for the cost of electricity. Recent chamber-transport simulations, however, indicate that changes in the beam ion species, the convergence angle, and the emittance might allow more-economical designs

  13. Ion transport Modeling in a Bipolar Membrane

    International Nuclear Information System (INIS)

    Kim, Jung Soo; Park, Kwang Heon; Kim, Kwang Wook

    2010-01-01

    The COL(Carbonate-based Oxidative Leaching) process is an environmentally-friendly technique for collecting only uranium from spent fuel with oxidation leaching/ precipitation of carbonate solution. The bipolar membrane used for the electrolyte circulation of the salt used in the COL process is a special form of ion exchange membrane which combines CEM(cation exchange membrane) and AEM(anion exchange membrane). After arranging positive ion exchange layer toward negative terminal and positive ion exchange layer toward positive terminal, then supply electricity, water molecules are decomposed into protons and hydroxyl ions by a strong electric field in the transition region inside bipolar membrane.1) In this study, a theoretical approach to increase the efficiency of Na + and NO3 - ion collecting device using bipolar membrane was taken and simulating using the COMSOL program was tried. The details of results are also discussed

  14. TTF/TCNQ-based thin films and microcrystals. Growth and charge transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Solovyeva, Vita

    2011-05-26

    The thesis adresses several problems related to growth and charge transport phenomena in thin films of TTF-TCNQ and (BEDT-TTF)TCNQ. The following main new problems are addressed: - The influence of thin-film specific factors, such as the substrate material and growth-induced defects, on the Peierls transition temperature in TTF-TCNQ thin films was studied; - finite-size effects in TTF-TCNQ were investigated by considering transport properties in TTF-TCNQ microcrystals. The influence of the size of the crystal on the Peierls transition temperature was studied. In this context a new method of microcontact fabrication was employed to favor the measurements; - an analysis of radiation-induced defects in TTF-TCNQ thin films and microcrystals was performed. It was demonstrated than an electron beam can induce appreciable damage to the sample such that its electronic properties are strongly modified; - a bilayer growth method was established to fabricate (BEDT-TTF)TCNQ from the gas phase. This newly developed bilayer growth method was showed to be suitable for testing (BEDT-TTF)TCNQ charge-transfer phase formation; - the structure of the formed (BEDT-TTF)TCNQ charge-transfer compounds was analyzed by using a wide range of experimental techniques. An overview and the description of the basic physical principles underlying charge-transfer compounds is given in chapter 2. Experimental techniques used for the growth and characterization of thin films and microcrystals are presented in chapter 3. Chapter 4 gives an overview of the physical properties of the studied organic materials. Chapter 5 discussed the experimental study of TTF-TCNQ thin films. he Peierls transition in TTF-TCNQ is a consequence of the quasi-one-dimensional structure of the material and depends on different factors, studied in chapters 5 and 6. In contradistinction to TTF-TTCNQ, the (BEDT-TTF)TCNQ charge-transfer compound crystallizes in several different modifications with different physical properties

  15. Twin boundary-assisted lithium-ion transport

    KAUST Repository

    Nie, Anmin; Gan, Liyong; Cheng, Yingchun; Li, Qianqian; Yuan, Yifei; Mashayek, Farzad; Wang, Hongtao; Klie, Robert F.; Schwingenschlö gl, Udo; Shahbazian-Yassar, Reza

    2015-01-01

    With the increased need for high-rate Li-ion batteries, it has become apparent that new electrode materials with enhanced Li-ion transport should be designed. Interfaces, such as twin boundaries (TBs), offer new opportunities to navigate the ionic

  16. Universal method for effusive-flow characterization target ion source/vapor transport systems for radioactive ion beam generation (abstract)

    International Nuclear Information System (INIS)

    Alton, G.D.; Bilheux, J.-C.; Liu, Y.; Cole, J. A.; Williams, C.

    2004-01-01

    Worldwide interest in the use of accelerated radioactive ion beams (RIBs) for exploring reactions important in understanding the structure of the nucleus and nuclear astrophysical phenomena has motivated the construction of facilities dedicated to their production and acceleration. Many facilities utilize the isotope-separator-on-line (ISOL) method in which species of interest are generated within a solid or liquid target matrix. Experimentally useful RIBs are often difficult to generate by this technique because of the times required for diffusion from the interior of the target material, and to effusively transport the species of interest to the ion source following diffusion release in relation to its lifetime. Therefore, these delay times must be minimized. We have developed an experimental method that can be used to determine effusive-flow times of arbitrary geometry target/vapor transport systems. The technique utilizes a fast valve to measure effusive-flow times as short as 0.1 ms for any chemically active or inactive species through any target system, independent of size, geometry and materials of construction. In this report, we provide a theoretical basis for effusive flow through arbitrary geometry vapor transport systems, describe a universal experimental apparatus for measuring effusive-flow times, and provide time spectra for noble gases through prototype RIB target/vapor-transport systems

  17. Giant resonance phenomena in the electron impact ionization of heavy atoms and ions

    International Nuclear Information System (INIS)

    Younger, S.M.

    1986-01-01

    Heavy atoms and ions offer an interesting opportunity to study atomic physics in a region where the atomic structure is dominated by the interelectronic interactions. One illustration of this is the profound term dependence of atomic orbitals for certain configurations of heavy atoms and ions. The appearance of giant scattering resonances in the cross sections for ionization of heavy atoms by electron impact is a manifestation of resonance behavior. Such resonant structures arise from the double well nature of the scattering potential and have recently been identified in the cross sections for the electron impact ionization of several xenon-like ions. The results of calculations showing effects for a variety of other ions are summarized. 7 refs., 4 figs

  18. Transport Phenomena in Nanowires, Nanotubes, and Other Low-Dimensional Systems

    KAUST Repository

    Montes, Enrique

    2017-01-01

    Nanoscale materials are not new in either nature or physics. However, the recent technological improvements have given scientists new tools to understand and quantify phenomena that occur naturally due to quantum confinement effects. In general, these phenomena induce remarkable optical, magnetic, and electronic properties in nanoscale materials in contrast to their bulk counterpart. In addition, scientists have recently developed the necessary tools to control and exploit these properties in electronic devices, in particular field effect transistors, magnetic memories, and gas sensors. In the present thesis we implement theoretical and computational tools for analyzing the ground state and electronic transport properties of nanoscale materials and their performance in electronic devices. The ground state properties are studied within density functional theory using the SIESTA code, whereas the transport properties are investigated using the non-equilibrium Green\\'s functions formalism implemented in the SMEAGOL code. First we study Si-based systems, as Si nanowires are believed to be important building blocks of the next generation of electronic devices. We derive the electron transport properties of Si nanowires connected to Au electrodes and their dependence on the nanowire growth direction, diameter, and length. At equilibrium Au-nanowire distance we find strong electronic coupling between electrodes and nanowire, resulting in low contact resistance. For the tunneling regime, the decay of the conductance with the nanowire length is rationalized using the complex band structure. The nanowires grown along the (110) direction show the smallest decay and the largest conductance and current. Due to the high spin coherence in Si, Si nanowires represent an interesting platform for spin devices. Therefore, we built a magnetic tunneling junction by connecting a (110) Si nanowire to ferromagnetic Fe electrodes. We have find a substantial low bias magnetoresistance of

  19. Phenomena of the ionic transport in the stress corrosion of metals

    International Nuclear Information System (INIS)

    Gravano, S.M.

    1986-07-01

    For the study of electrochemical conditions of propagation, a model which calculates the concentrations and potential profiles inside cracks or localized corrosion cavities, was developed. Considering transport by difussion and migration it was applied to pure metals (Zn, Fe) in solutions where pitting occurs (NaCl or Na2SO4, with borate buffer), and also extended to systems where stress corrosion cracking is present, such as Cu and yellow brass in NaNO2. Physical bases of the 'constant intermediate elongation rate technique' to predict stress corrosion cracking susceptibility was analized, studying by mathematical models: 1) dissolution current, that should be the result of superposition of repassivation transients on the fresh metal, exposed to corrosive medium by strain, with the same rate of that of a static specimen; 2) ohmic drop, that in some systems could be quite important and it must be considered in the overpotential evaluation; and 3) metallic ion concentration that, instead of what happens in a crack, never attains saturation in the analized cases. For repassivation transient according to the crak propagation models proposed by Scully and Ford it was found that, at the tip of the crack, it is unlikely that the same repassivation transients occur as in the constant intermediate elongation rate experiments. (M.E.L.)

  20. Charge Transport Phenomena in Detectors of the Cryogenic Dark Matter Search

    Science.gov (United States)

    Sundqvist, Kyle

    2008-03-01

    The Cryogenic Dark Matter Search (CDMS) seeks to detect putative weakly-interacting massive particles (WIMPS), which could explain the dark matter problem in cosmology and particle physics. By simultaneously measuring the number of charge carriers and the energy in athermal phonons created by particle interactions in intrinsic Ge and Si crystals at a temperature of 40 mK, a signature response for each event is produced. This response, combined with phonon pulse-shape information, allows CDMS to actively discriminate candidate WIMP interactions with nuclei apart from electromagnetic radioactive background which interacts with electrons. The challenges associated with these techniques are unique. Carrier drift-fields are maintained at only a few V/cm, else drift-emitted Luke-Neganov phonons would dominate the phonons of the original interaction. Under such conditions, carrier scattering is dominated by zero-point fluctuations of the lattice ions. It has been an open question how well the 8 Kelvin data prominent in the literature depicts this case. We compare the simulated transport properties of electrons and holes in Ge at 40 mK and at 8 K, and apply this understanding to our detectors.

  1. Passive water and ion transport by cotransporters

    DEFF Research Database (Denmark)

    Loo, D D; Hirayama, B A; Meinild, A K

    1999-01-01

    the Lp of control oocytes. Passive Na+ transport (Na+ leak) was obtained from the blocker-sensitive Na+ currents in the absence of substrates (glucose and GABA). 2. Passive Na+ and water transport through SGLT1 were blocked by phlorizin with the same sensitivity (inhibitory constant (Ki), 3-5 micro......1. The rabbit Na+-glucose (SGLT1) and the human Na+-Cl--GABA (GAT1) cotransporters were expressed in Xenopus laevis oocytes, and passive Na+ and water transport were studied using electrical and optical techniques. Passive water permeabilities (Lp) of the cotransporters were determined from......M). When Na+ was replaced with Li+, phlorizin also inhibited Li+ and water transport, but with a lower affinity (Ki, 100 microM). When Na+ was replaced by choline, which is not transported, the SGLT1 Lp was indistinguishable from that in Na+ or Li+, but in this case water transport was less sensitive...

  2. PHITS-a particle and heavy ion transport code system

    International Nuclear Information System (INIS)

    Niita, Koji; Sato, Tatsuhiko; Iwase, Hiroshi; Nose, Hiroyuki; Nakashima, Hiroshi; Sihver, Lembit

    2006-01-01

    The paper presents a summary of the recent development of the multi-purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS. In particular, we discuss in detail the development of two new models, JAM and JQMD, for high energy particle interactions, incorporated in PHITS, and show comparisons between model calculations and experiments for the validations of these models. The paper presents three applications of the code including spallation neutron source, heavy ion therapy and space radiation. The results and examples shown indicate PHITS has great ability of carrying out the radiation transport analysis of almost all particles including heavy ions within a wide energy range

  3. Computational analysis of interfacial attachment kinetics and transport phenomena during liquid phase epitaxy of mercury cadmium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Rasin, Igal; Brandon, Simon [Dept. of Chemical Engineering, Technion, Haifa 32000 (Israel); Ben Dov, Anne; Grimberg, Ilana; Klin, Olga; Weiss, Eliezer [SCD-Semi-Conductor Devices, P.O. Box 2250/99, Haifa 31021 (Israel)

    2010-07-01

    Deposition of mercury cadmium telluride (MCT) thin films, on lattice matched cadmium zinc telluride substrates, is often achieved via Liquid Phase Epitaxy (LPE). The yield and quality of these films, required for the production of infrared detector devices, is to a large extent limited by lack of knowledge regarding details of physical phenomena underlying the deposition process. Improving the understanding of these phenomena and their impact on the quality of the resultant films is therefore an important goal which can be achieved through relevant computational and/or experimental studies. We present a combined computational and experimental effort aimed at elucidating physical phenomena underlying the LPE of MCT via a slider growth process. The focus of the presentation will be results generated by a time-dependent three-dimensional model of mass transport, fluid flow, and interfacial attachment kinetics, which we have developed and applied in the analysis of this LPE process. These results, combined with experimental analyses, lead to an improved understanding of the role of different transport and kinetic phenomena underlying this growth process.

  4. Generation and transport of laser accelerated ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Peter; Boine-Frankenheim, Oliver [Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Kornilov, Vladimir; Spaedtke, Peter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Collaboration: LIGHT-Collaboration

    2013-07-01

    Currently the LIGHT- Project (Laser Ion Generation, Handling and Transport) is performed at the GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt. Within this project, intense proton beams are generated by laser acceleration, using the TNSA mechanism. After the laser acceleration the protons are transported through the beam pipe by a pulsed power solenoid. To study the transport a VORPAL 3D simulation is compared with CST simulation. A criterion as a function of beam parameters was worked out, to rate the importance of space charge. Furthermore, an exemplary comparison of the solenoid with a magnetic quadrupole-triplet was carried out. In the further course of the LIGHT-Project, it is planned to generate ion beams with higher kinetic energies, using ultra-thin targets. The acceleration processes that can appear are: RPA (Radiation Pressure Acceleration) and BOA (Break-Out Afterburner). Therefore the transport of an ion distribution will be studied, as it emerges from a RPA acceleration.

  5. Transport of negative hydrogen and deuterium ions in RF-driven ion sources

    International Nuclear Information System (INIS)

    Gutser, R; Wuenderlich, D; Fantz, U

    2010-01-01

    Negative hydrogen ion sources are major components of neutral beam injection systems for plasma heating in future large-scale fusion experiments such as ITER. In order to fulfill the requirements of the ITER neutral beam injection, a high-performance, large-area RF-driven ion source for negative ions is being developed at the MPI fuer Plasmaphysik. Negative hydrogen ions are mainly generated on a converter surface by impinging neutral particles and positive ions under the influence of magnetic fields and the plasma sheath potential. The 3D transport code TrajAn has been applied in order to obtain the total and spatially resolved extraction probabilities for H - and D - ions under identical plasma parameters and the realistic magnetic field topology of the ion source. A comparison of the isotopes shows a lower total extraction probability in the case of deuterium ions, caused by a different transport effect. The transport calculation shows that distortions of the spatial distributions of ion birth and extraction by the magnetic electron suppression field are present for both negative hydrogen and deuterium ions.

  6. [Anomalous ion transport and feedback control

    International Nuclear Information System (INIS)

    1993-01-01

    The slab branch of the ITG mode was produced by a d.c. ion acceleration heating scheme and definitively identified in CLM under the previous DOE grant. A transit-time rf heating scheme was used to produce a more Maxwellian ion population to produce and identify a more predictable slab ITG mode. These experiments are partly based on some theoretical work on the substantial effects of anisotropy in η i on the slab mode. The progress under the present DOE grant are described below

  7. Parallel Transport Quantum Logic Gates with Trapped Ions.

    Science.gov (United States)

    de Clercq, Ludwig E; Lo, Hsiang-Yu; Marinelli, Matteo; Nadlinger, David; Oswald, Robin; Negnevitsky, Vlad; Kienzler, Daniel; Keitch, Ben; Home, Jonathan P

    2016-02-26

    We demonstrate single-qubit operations by transporting a beryllium ion with a controlled velocity through a stationary laser beam. We use these to perform coherent sequences of quantum operations, and to perform parallel quantum logic gates on two ions in different processing zones of a multiplexed ion trap chip using a single recycled laser beam. For the latter, we demonstrate individually addressed single-qubit gates by local control of the speed of each ion. The fidelities we observe are consistent with operations performed using standard methods involving static ions and pulsed laser fields. This work therefore provides a path to scalable ion trap quantum computing with reduced requirements on the optical control complexity.

  8. Twin boundary-assisted lithium-ion transport

    KAUST Repository

    Nie, Anmin

    2015-01-14

    With the increased need for high-rate Li-ion batteries, it has become apparent that new electrode materials with enhanced Li-ion transport should be designed. Interfaces, such as twin boundaries (TBs), offer new opportunities to navigate the ionic transport within nanoscale materials. Here, we demonstrate the effects of TBs on the Li-ion transport properties in single crystalline SnO2 nanowires. It is shown that the TB-assisted lithiation pathways are remarkably different from the previously reported lithiation behavior in SnO2 nanowires without TBs. Our in situ transmission electron microscopy study combined with direct atomic-scale imaging of the initial lithiation stage of the TB-SnO2 nanowires prove that the lithium ions prefer to intercalate in the vicinity of the (101¯) TB, which acts as conduit for lithium-ion diffusion inside the nanowires. The density functional theory modeling shows that it is energetically preferred for lithium ions to accumulate near the TB compared to perfect neighboring lattice area. These findings may lead to the design of new electrode materials that incorporate TBs as efficient lithium pathways, and eventually, the development of next generation rechargeable batteries that surpass the rate performance of the current commercial Li-ion batteries.

  9. The role of space charge compensation for ion beam extraction and ion beam transport (invited)

    International Nuclear Information System (INIS)

    Spädtke, Peter

    2014-01-01

    Depending on the specific type of ion source, the ion beam is extracted either from an electrode surface or from a plasma. There is always an interface between the (almost) space charge compensated ion source plasma, and the extraction region in which the full space charge is influencing the ion beam itself. After extraction, the ion beam is to be transported towards an accelerating structure in most cases. For lower intensities, this transport can be done without space charge compensation. However, if space charge is not negligible, the positive charge of the ion beam will attract electrons, which will compensate the space charge, at least partially. The final degree of Space Charge Compensation (SCC) will depend on different properties, like the ratio of generation rate of secondary particles and their loss rate, or the fact whether the ion beam is pulsed or continuous. In sections of the beam line, where the ion beam is drifting, a pure electrostatic plasma will develop, whereas in magnetic elements, these space charge compensating electrons become magnetized. The transport section will provide a series of different plasma conditions with different properties. Different measurement tools to investigate the degree of space charge compensation will be described, as well as computational methods for the simulation of ion beams with partial space charge compensation

  10. Ion transport in circulatory and/or septic shock

    International Nuclear Information System (INIS)

    Sayeed, M.M.

    1987-01-01

    This review surveys investigations of membrane ion transport in animals in hemorrhagic, endotoxic, or bacteremic shock. The focus of the review is on ion transport studies in the skeletal muscle and liver. Skeletal muscle Na + -K + transport alterations have been shown during the induction of shock via hemorrhage, endotoxin, or live Gram-negative bacteria in the rodent, canine, and primate species. These alterations include impairment of active cellular K + accumulation, increased permeability to 24 Na + and Cl - , and membrane depolarization. The ion transport alterations in the skeletal muscle are compatible with movement of extracellular fluid into the intracellular compartment. Such fluid movements can potentially lead to decreases in circulating plasma volume and thus to circulatory deficits in shock. Studies in the liver of rats subjected to hemorrhagic or endotoxic shock indicated the failure of electrogenic Na + pump. Although the hepatic cellular membrane permeability to Na + relative to permeability to K + appeared unaltered in hemorrhagic shock, endotoxic shock caused an increase in permeability to Na + . Hepatic cellular 45 Ca + regulation also appeared to be adversely affected during endotoxic shock. Alterations in hepatic Na + -K + transport and Ca + regulation could contribute to impairment in hepatic glucose production during shock. Although mechanisms of altered membrane ion transport during shock states remain unknown, such changes could occur prior to any substantial loss of cellular metabolic energy

  11. Ballistic-neutralized chamber transport of intense heavy ion beams

    International Nuclear Information System (INIS)

    Rose, D.V.; Welch, D.R.; Oliver, B.V.; Clark, R.E.; Sharp, W.M.; Friedman, A.

    2001-01-01

    Two-dimensional particle-in-cell simulations of intense heavy ion beams propagating in an inertial confinement fusion (ICF) reactor chamber are presented. The ballistic-neutralized transport scheme studied uses 4 GeV Pb +1 ion beams injected into a low-density, gas-filled reactor chamber and the beam is ballistically focused onto an ICF target before entering the chamber. Charge and current neutralization of the beam is provided by the low-density background gas. The ballistic-neutralized simulations include stripping of the beam ions as the beam traverses the chamber as well as ionization of the background plasma. In addition, a series of simulations are presented that explore the charge and current neutralization of the ion beam in an evacuated chamber. For this vacuum transport mode, neutralizing electrons are only drawn from sources near the chamber entrance

  12. Transport of secondary electrons and reactive species in ion tracks

    Science.gov (United States)

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2015-08-01

    The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

  13. Lithium-ion transport in inorganic solid state electrolyte

    International Nuclear Information System (INIS)

    Gao Jian; Li Hong; Zhao Yu-Sheng; Shi Si-Qi

    2016-01-01

    An overview of ion transport in lithium-ion inorganic solid state electrolytes is presented, aimed at exploring and designing better electrolyte materials. Ionic conductivity is one of the most important indices of the performance of inorganic solid state electrolytes. The general definition of solid state electrolytes is presented in terms of their role in a working cell (to convey ions while isolate electrons), and the history of solid electrolyte development is briefly summarized. Ways of using the available theoretical models and experimental methods to characterize lithium-ion transport in solid state electrolytes are systematically introduced. Then the various factors that affect ionic conductivity are itemized, including mainly structural disorder, composite materials and interface effects between a solid electrolyte and an electrode. Finally, strategies for future material systems, for synthesis and characterization methods, and for theory and calculation are proposed, aiming to help accelerate the design and development of new solid electrolytes. (topical review)

  14. Dust particle diffusion in ion beam transport region

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, N.; Okajima, Y.; Romero, C. F.; Kuwata, Y.; Kasuya, T.; Wada, M., E-mail: mwada@mail.doshisha.ac.jp [Graduate school of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321 (Japan)

    2016-02-15

    Dust particles of μm size produced by a monoplasmatron ion source are observed by a laser light scattering. The scattered light signal from an incident laser at 532 nm wavelength indicates when and where a particle passes through the ion beam transport region. As the result, dusts with the size more than 10 μm are found to be distributed in the center of the ion beam, while dusts with the size less than 10 μm size are distributed along the edge of the ion beam. Floating potential and electron temperature at beam transport region are measured by an electrostatic probe. This observation can be explained by a charge up model of the dust in the plasma boundary region.

  15. A CFD analysis of transport phenomena and electrochemical reactions in a tubular-shaped PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Al-Najaf, P.O.Box 39 (Iraq)

    2013-07-01

    A fuel cell is most interesting new power source because it solves not only the environment problem but also natural resource exhaustion problem. CFD modeling and simulation for heat and mass transport in PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a tubular-shaped proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a tubular-shaped PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

  16. Numerical assessment of the ion turbulent thermal transport scaling laws

    International Nuclear Information System (INIS)

    Ottaviani, M.; Manfredi, G.

    2001-01-01

    Numerical simulations of ion temperature gradient (ITG) driven turbulence were carried out to investigate the parametric dependence of the ion thermal transport on the reduced gyroradius and on the local safety factor. Whereas the simulations show a clear proportionality of the conductivity to the gyroradius, the dependence on the safety factor cannot be represented as a simple power law like the one exhibited by the empirical scaling laws. (author)

  17. Realistic modeling of chamber transport for heavy-ion fusion

    International Nuclear Information System (INIS)

    Sharp, W.M.; Grote, D.P.; Callahan, D.A.; Tabak, M.; Henestroza, E.; Yu, S.S.; Peterson, P.F.; Welch, D.R.; Rose, D.V.

    2003-01-01

    Transport of intense heavy-ion beams to an inertial-fusion target after final focus is simulated here using a realistic computer model. It is found that passing the beam through a rarefied plasma layer before it enters the fusion chamber can largely neutralize the beam space charge and lead to a usable focal spot for a range of ion species and input conditions

  18. Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

    KAUST Repository

    Hong, Jongsup; Kirchen, Patrick; Ghoniem, Ahmed F.

    2012-01-01

    Ion transport membrane (ITM) based reactors have been suggested as a novel technology for several applications including fuel reforming and oxy-fuel combustion, which integrates air separation and fuel conversion while reducing complexity

  19. Efficient Simulation and Abuse Modeling of Mechanical-Electrochemical-Thermal Phenomena in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Shriram [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Smith, Kandler A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Graf, Peter A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pesaran, Ahmad A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Chao [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lamb, Joshua [Sandia National Laboratories; Abraham, Daniel [Argonne National Laboratory; Dees, Dennis [Argonne National Laboratory; Yao, Pierre [Argonne National Laboratory

    2017-08-08

    NREL's Energy Storage team is exploring the effect of mechanical crush of lithium ion cells on their thermal and electrical safety. PHEV cells, fresh as well as ones aged over 8 months under different temperatures, voltage windows, and charging rates, were subjected to destructive physical analysis. Constitutive relationship and failure criteria were developed for the electrodes, separator as well as packaging material. The mechanical models capture well, the various modes of failure across different cell components. Cell level validation is being conducted by Sandia National Laboratories.

  20. Estimates of Ionospheric Transport and Ion Loss at Mars

    Science.gov (United States)

    Cravens, T. E.; Hamil, O.; Houston, S.; Bougher, S.; Ma, Y.; Brain, D.; Ledvina, S.

    2017-10-01

    Ion loss from the topside ionosphere of Mars associated with the solar wind interaction makes an important contribution to the loss of volatiles from this planet. Data from NASA's Mars Atmosphere and Volatile Evolution mission combined with theoretical modeling are now helping us to understand the processes involved in the ion loss process. Given the complexity of the solar wind interaction, motivation exists for considering a simple approach to this problem and for understanding how the loss rates might scale with solar wind conditions and solar extreme ultraviolet irradiance. This paper reviews the processes involved in the ionospheric dynamics. Simple analytical and semiempirical expressions for ion flow speeds and ion loss are derived. In agreement with more sophisticated models and with purely empirical studies, it is found that the oxygen loss rate from ion transport is about 5% (i.e., global O ion loss rate of Qion ≈ 4 × 1024 s-1) of the total oxygen loss rate. The ion loss is found to approximately scale as the square root of the solar ionizing photon flux and also as the square root of the solar wind dynamic pressure. Typical ion flow speeds are found to be about 1 km/s in the topside ionosphere near an altitude of 300 km on the dayside. Not surprisingly, the plasma flow speed is found to increase with altitude due to the decreasing ion-neutral collision frequency.

  1. Transport phenomena of macro and micro flows behind orifice and flow accelerated corrosion

    International Nuclear Information System (INIS)

    Fujisawa, Nobuyuki; Hayase, Toshiyuki; Ohara, Taku; Ikohagi, Toshiaki

    2008-01-01

    This paper describes experiment and numerical simulations for macro and micro flows behind an orifice model in a square pipe, which are carried from the viewpoint of flow accelerated corrosion (FAC). The measurements of velocity field behind the orifice model were carried out using particle image velocimetry, and the variations of velocity field with respect to the accuracy of the orifice position were studied. It is found that the reattachment behavior of the flow is highly influenced by the orifice position, which is a critical problem for predicting the pipe thinning phenomena by FAC. The DNS simulation was also conducted for calculating the macro flow behind the orifice. The result suggests that the DNS simulation is applicable to the prediction of pipe thinning macro flow for highly aged nuclear plant. The micro flow simulation can predict the pipe thinning phenomena near the wall. (author)

  2. Ion transport in sub-5-nm graphene nanopores

    International Nuclear Information System (INIS)

    Suk, Myung E.; Aluru, N. R.

    2014-01-01

    Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors

  3. THE EFFECTS OF SICKLING ON ION TRANSPORT

    Science.gov (United States)

    Tosteson, D. C.; Carlsen, E.; Dunham, E. T.

    1955-01-01

    The conversion of red cells of patients with sickle cell anemia (S-S) from biconcave disk to sickle shape by removal of oxygen was found to increase the fraction of medium trapped in cells packed by centrifugation from 0.036 (S.E. 0.003) to 0.106 (S.E. 0.004). The fraction of water in the cells (corrected for trapped medium) was not affected by this shape transformation. Cation transport, however, was changed profoundly. S-S cells incubated in N2 rather than O2 showed net K loss with acceleration of both influx and outflux. That this change in K transport was due to the process of sickling was indicated by (1) the persistence of the effect in the absence of plasma, (2) the absence of the effect in hypoxic S-S cells in which sickling was inhibited by alkali or carbon monoxide, (3) the reversal of the effect when sickling was reversed by exposure to O2, and (4) the independence of the effect from such potentially important factors as age of the cell population. The acceleration of K transport by sickling is probably mediated by modification of the cell surface rather than the cell interior since concentrated sickle hemoglobin solutions in O2 or N2 did not show selective affinity for K. In molecular terms, the effect of sickling on K transport can be explained by presuming that the shape change (1) opens pathways for the free diffusion of K, and (2) accelerates K transport by a non-diffusion carrier process. The evidence for the former mechanism included (a) dependence of K influx into sickled cells on the concentration of K in the medium, and (b) increase in the total cation content of sickled cells with increasing pH. Observations suggestive of a carrier process included (a) the failure of sickled cell K concentration to become equal to external K concentration even after 48 hours, (b) the deviation of the flux ratio from that characteristic of diffusion, and (c) the dependence of K influx on glycolysis. PMID:13252234

  4. Transport and error sensitivity in a heavy-ion recirculator

    International Nuclear Information System (INIS)

    Sharp, W.M.; Barnard, J.J.; Yu, S.S.

    1991-05-01

    An envelope code has been developed to facilitate the design of a recirculating accelerator for a heavy-ion fusion reactor. A novel feature of the model is the treatment of the beam charge density as a Lagrangian fluid in the axial direction. Transport results for a preliminary recirculator design are presented, and sensitivity of the transport to errors in the magnet strength is discussed. 4 refs., 4 figs

  5. Unified description of scattering and fusion phenomena in heavy-ion collisions

    International Nuclear Information System (INIS)

    Sahu, Basudeb; Sahu, B. B.; Mallick, G. S.; Agarwalla, S. K.; Shastry, C. S.

    2008-01-01

    An analytical recursive formula of the partial-wave scattering matrix for the total effective complex potential of nucleus-nucleus collisions is derived to conveniently analyze the data of angular variations of elastic scattering cross sections. Further, another expression of cross sections for the absorption from arbitrarily small intervals is derived. This leads to the explanation of the fusion cross section (σ fus ) data at various incident center-of-mass energies E c.m. by collecting the absorption contributions in the interior region of the effective potential. This concept is akin to that used by Udagawa et al. in the calculation of fusion cross sections in elastic channels. The interaction potential considered in the analysis is energy independent and by virtue of its weakly absorbing character it supports resonance states in different partial-wave trajectories. Consequently, occurrence of these resonances is shown to be the physical origin of the observed oscillatory structure in the variation respect to energy of the quantity D(E c.m. )=d 2 (E c.m. σ fus )/dE c.m. 2 , the second derivative of the product E c.m. σ fus with respect to E c.m. . In this article, we investigate two well-known cases of heavy-ion collisions, namely 12 C+ 208 Pb and 16 O+ 208 Pb, and obtain simultaneous and very successful explanations of cross sections for elastic scattering and fusion and the results of D(E c.m. ). These results obtained by using a somewhat novel and convenient method demonstrate the unified description of scattering and fusion for interacting heavy-ion systems

  6. Ion transport in deep-sea sediments

    International Nuclear Information System (INIS)

    Heath, G.R.

    1979-01-01

    Initial assessment of the ability of deep-sea clays to contain nuclear waste is optimistic. Yet, the investigators have no delusions about the complexity of the natural geochemical system and the perturbations that may result from emplacement of thermally-hot waste cannisters. Even though they may never be able to predict the exact nature of all these perturbations, containment of the nuclides by the waste form/cannister system until most of the heat has decayed, and burial of the waste to a sufficient depth that the altered zone can be treated as a black box source of dissolved nuclides to the enclosing unperturbed sediment, encourage them to believe that ion migration in the deep seabed can be modeled accurately and that our preliminary estimates of migration rates are likely to be reasonably realistic

  7. Fast transient transport phenomena measured by soft X-ray emission in TCV tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Furno, I. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    2001-08-01

    Energy and particle transport during sawtooth activity in TCV plasmas has been studied in this thesis with high temporal resolution many chord diagnostics. We indicated the influence of sawteeth on plasma profiles in ohmic conditions and in the presence of auxiliary electron cyclotron resonance heating and current drive. A 2-dimensional model for heat transport, including localised heat source and a magnetic island, has been used to interpret the experimental observations. These results provided a new interpretation of a coupled heat and transport phenomenon which is potentially important for plasma confinement. The observations validate the applicability and show the possibility of improvement of a 2-dimensional theoretic a1 model for the study of heat transport in the presence of localised heat source and a magnetic island. Furthermore, the TCV results showed a new possibility for the interpretation of a coupled heat and particle transport phenomenon previously understood only in stellarators. (author)

  8. Engineering a spin-fet: spin-orbit phenomena and spin transport induced by a gate electric field

    OpenAIRE

    Cardoso, J. L.; Hernández-Saldaña, H.

    2012-01-01

    In this work, we show that a gate electric field, applied in the base of the field-effect devices, leads to inducing spin-orbit interactions (Rashba and linear Dresselhauss) and confines the transport electrons in a two-dimensional electron gas. On the basis of these phenomena we solve analytically the Pauli equation when the Rashba strength and the linear Dresselhaus one are equal, for a tuning value of the gate electric field $\\mathcal{E}_g^*$. Using the transfer matrix approach, we provide...

  9. Electric Field Mediated Ion Transport Through Charged Mesoporous Membranes

    NARCIS (Netherlands)

    Schmuhl, R.; de Lint, W.B.S.; Keizer, Klaas; van den Berg, Albert; ten Elshof, Johan E.; Burganos, Vasilis N.; Noble, Richard D.; Asaeda, Masashi; Ayral, Andre; LeRoux, Johann D.

    2003-01-01

    The transport of ions from aqueous solutions through a stacked Au/alpha-alumina/gamma-alumina/Au membrane under the influence of a dc potential difference is reported. The membrane shows high cation permselectivity at ionic strengths of ~1 mM at pH 4.3-6.5, which is associated with a combination of

  10. Vocal fold ion transport and mucin expression following acrolein exposure.

    Science.gov (United States)

    Levendoski, Elizabeth Erickson; Sivasankar, M Preeti

    2014-05-01

    The vocal fold epithelium is exposed to inhaled particulates including pollutants during breathing in everyday environments. Yet, our understanding of the effects of pollutants on vocal fold epithelial function is extremely limited. The objective of this study was to investigate the effect of the pollutant acrolein on two vocal fold epithelial mechanisms: ion transport and mucin (MUC) synthesis. These mechanisms were chosen as each plays a critical role in vocal defense and in maintaining surface hydration which is necessary for optimal voice production. Healthy, native porcine vocal folds (N = 85) were excised and exposed to an acrolein or sham challenge. A 60-min acrolein, but not sham challenge significantly reduced ion transport and inhibited cyclic adenosine monophosphate-dependent, increases in ion transport. Decreases in ion transport were associated with reduced sodium absorption. Within the same timeline, no significant acrolein-induced changes in MUC gene or protein expression were observed. These results improve our understanding of the effects of acrolein on key vocal fold epithelial functions and inform the development of future investigations that seek to elucidate the impact of a wide range of pollutant exposures on vocal fold health.

  11. Ion transport restriction in mechanically strained separator membranes

    Science.gov (United States)

    Cannarella, John; Arnold, Craig B.

    2013-03-01

    We use AC impedance methods to investigate the effect of mechanical deformation on ion transport in commercial separator membranes and lithium-ion cells as a whole. A Bruggeman type power law relationship is found to provide an accurate correlation between porosity and tortuosity of deformed separators, which allows the impedance of a separator membrane to be predicted as a function of deformation. By using mechanical compression to vary the porosity of the separator membranes during impedance measurements it is possible to determine both the α and γ parameters from the modified Bruggeman relation for individual separator membranes. From impedance testing of compressed pouch cells it is found that separator deformation accounts for the majority of the transport restrictions arising from compressive stress in a lithium-ion cell. Finally, a charge state dependent increase in the impedance associated with charge transfer is observed with increasing cell compression.

  12. Radial transport of storm time ring current ions

    Science.gov (United States)

    Lui, A. T. Y.

    1993-01-01

    Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer spacecraft, which monitored protons, helium ions, and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions. From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region can be accounted for by an inward displacement of the ring current population by 0.5 to 3.5 R(E). There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter time scale than that for a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations.

  13. Modeling conversion and transport phenomena in solid-state fermentation: a review and perspectives

    NARCIS (Netherlands)

    Rahardjo, Y.S.P.; Tramper, J.; Rinzema, A.

    2006-01-01

    Solid-state fermentation (SSF) is accompanied inevitably by development of concentration and temperature gradients within the substrate particles and microbial biofilms. These gradients are needed for driving the transport of substrates and products. In addition, concentration gradients have been

  14. Experimental and analytical study of interfacial area transport phenomena in a vertical two-phase flow

    International Nuclear Information System (INIS)

    Huh, Byung-Gil; Euh, Dong-Jin; Yun, Byong-Jo; Youn, Young-Jung; Yoon, Han-Yeong; Song, Chul-Hwa

    2005-03-01

    The number density transport equations for various bubble groups are used to predict the void fraction and the interfacial area concentration. As the closure relations for number density transport equation, the coalescence due to random collisions and the breakup due to the impact of turbulent eddies is modified based on the previous studies and the bubble expansion term due to the pressure reduction is considered. Also, the coalescence due to a wake entrainment is modeled newly to apply to the number density transport equation. In order to predict the local experimental data, the code is developed that the two-fluid model is coupled systematically with the number density transport equation for each bubble group. As for the results of the numerical analysis, the void fraction and interfacial area concentration are predicted well by the developed code and models although some deviations exist in the values between the prediction and experiment, especially, for the high void fraction conditions

  15. Mathematical interpretation of Brownian motor model: Limit cycles and directed transport phenomena

    Science.gov (United States)

    Yang, Jianqiang; Ma, Hong; Zhong, Suchuang

    2018-03-01

    In this article, we first suggest that the attractor of Brownian motor model is one of the reasons for the directed transport phenomenon of Brownian particle. We take the classical Smoluchowski-Feynman (SF) ratchet model as an example to investigate the relationship between limit cycles and directed transport phenomenon of the Brownian particle. We study the existence and variation rule of limit cycles of SF ratchet model at changing parameters through mathematical methods. The influences of these parameters on the directed transport phenomenon of a Brownian particle are then analyzed through numerical simulations. Reasonable mathematical explanations for the directed transport phenomenon of Brownian particle in SF ratchet model are also formulated on the basis of the existence and variation rule of the limit cycles and numerical simulations. These mathematical explanations provide a theoretical basis for applying these theories in physics, biology, chemistry, and engineering.

  16. Experimental and analytical study of interfacial area transport phenomena in a vertical two-phase flow

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Byung-Gil; Euh, Dong-Jin; Yun, Byong-Jo; Youn, Young-Jung; Yoon, Han-Yeong; Song, Chul-Hwa

    2005-03-01

    The number density transport equations for various bubble groups are used to predict the void fraction and the interfacial area concentration. As the closure relations for number density transport equation, the coalescence due to random collisions and the breakup due to the impact of turbulent eddies is modified based on the previous studies and the bubble expansion term due to the pressure reduction is considered. Also, the coalescence due to a wake entrainment is modeled newly to apply to the number density transport equation. In order to predict the local experimental data, the code is developed that the two-fluid model is coupled systematically with the number density transport equation for each bubble group. As for the results of the numerical analysis, the void fraction and interfacial area concentration are predicted well by the developed code and models although some deviations exist in the values between the prediction and experiment, especially, for the high void fraction conditions.

  17. Modeling of the Transport Phenomena in Passive Direct Methanol Fuel Cells Using a Two-Phase Anisotropic Model

    Directory of Open Access Journals (Sweden)

    Zheng Miao

    2014-04-01

    Full Text Available The transport phenomena in a passive direct methanol fuel cell (DMFC were numerically simulated by the proposed two-dimensional two-phase nonisothermal mass transport model. The anisotropic transport characteristic and deformation of the gas diffusion layer (GDL were considered in this model. The natural convection boundary conditions were adopted for the transport of methanol, oxygen, and heat at the GDL outer surface. The effect of methanol concentration in the reservoir on cell performance was examined. The distribution of multiphysical fields in the membrane electrode assembly (MEA, especially in the catalyst layers (CLs, was obtained and analyzed. The results indicated that transport resistance for the methanol mainly existed in the MEA while that for oxygen and heat was primarily due to natural convection at the GDL outer surface. Because of the relatively high methanol concentration, the local reaction rate in CLs was mainly determined by the overpotential. Methanol concentration between 3 M and 4 M was recommended for passive liquid feed DMFC in order to achieve a balance between the cell performance and the methanol crossover.

  18. Investigations on transport and storage of high ion beam intensities

    International Nuclear Information System (INIS)

    Joshi, Ninad Shrikrishna

    2009-01-01

    In the framework of this thesis the intense low energy ion beam transport was investigated. Especially, the beam transport in toroidal magnetic field configurations was discussed, as it may allow the accumulation of high intensive beams in the future. One of the specific tasks is to design an injection system that can be used for the proposed low energy accumulator ring. A simulation code (TBT) was written to describe the particle motion in curved segments. Particle in Cell techniques were utilized to simulate a multi particle dynamics. A possibility of reading an external data file was made available so that a measured distribution can be used to compare simulation results with measured ones. A second order cloud in cell method was used to calculate charge density and in turn to solve Poisson's equation. Further simulations were performed to study the self field effects on beam transport. Experiments were performed to compare the simulation results and gain practical experience. The preparatory experiments consisted of building and characterization of the ion source in a first step. Along with the momentum spectrometer and emittance scanner the beam properties were studied. Low mass ion beams He + and mixed p, H 2+ , H 3+ beams were analyzed. In the second stage, beams were transported through a solenoid and the phase space distribution was measured as a function of the magnetic field for different beam energies. The phase-space as distributions measured in a first stage were simulated backward and then again forward transported through the solenoid. The simulated results were then compared with the measured distribution. The LINTRA transport program was used. The phase-space distribution was further simulated for transport experiments in a toroidal magnetic field. The transport program that was used to simulate the beam in the toroid was also used to design the injection system. The injection system with its special field configurations was designed to perform

  19. Investigations on transport and storage of high ion beam intensities

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Ninad Shrikrishna

    2009-08-25

    In the framework of this thesis the intense low energy ion beam transport was investigated. Especially, the beam transport in toroidal magnetic field configurations was discussed, as it may allow the accumulation of high intensive beams in the future. One of the specific tasks is to design an injection system that can be used for the proposed low energy accumulator ring. A simulation code (TBT) was written to describe the particle motion in curved segments. Particle in Cell techniques were utilized to simulate a multi particle dynamics. A possibility of reading an external data file was made available so that a measured distribution can be used to compare simulation results with measured ones. A second order cloud in cell method was used to calculate charge density and in turn to solve Poisson's equation. Further simulations were performed to study the self field effects on beam transport. Experiments were performed to compare the simulation results and gain practical experience. The preparatory experiments consisted of building and characterization of the ion source in a first step. Along with the momentum spectrometer and emittance scanner the beam properties were studied. Low mass ion beams He{sup +} and mixed p, H{sup 2+}, H{sup 3+} beams were analyzed. In the second stage, beams were transported through a solenoid and the phase space distribution was measured as a function of the magnetic field for different beam energies. The phase-space as distributions measured in a first stage were simulated backward and then again forward transported through the solenoid. The simulated results were then compared with the measured distribution. The LINTRA transport program was used. The phase-space distribution was further simulated for transport experiments in a toroidal magnetic field. The transport program that was used to simulate the beam in the toroid was also used to design the injection system. The injection system with its special field configurations was

  20. Quantification of ion or atom transfer phenomena in materials implanted by nuclear methods

    International Nuclear Information System (INIS)

    Oudadesse, Hassane

    1998-01-01

    Knowledge of transfer of the constituents of a system from regions of higher to lower concentration is of interest for implanted bio-materials. It allows determining the rate at which this material is integrated in a living material. To evaluate the ossification kinetics and to study the bio-functionality in corals of Ca and Sr, irradiations with a 10 13 n.cm -2 .s -1 was performed, followed by the examination of changes in the localization of these elements. By using PIXE analysis method the distribution of Ca, P, Sr, Zn and Fe in the implant, bone and bone-implant interfaces were determined. Thus, it was shown that resorption of coral in sheep is achieved in 5 months after implantation and is identical to the cortical tissues 4 months after implantation in animals as for instance in hares. We have analyzed the tissues from around the prostheses extracted from patients. The samples were calcined and reduced to powder weighting some milligrams. We have adopted for this study the PIXE analysis method. The samples were irradiated by a proton beam of 3 MeV and about 400 μm diameter. The results show the presence of the elements Ti, Fe, Cr, Ni or Zn according to the type of the implanted prosthesis. This dispersal of the metallic ions and atoms contaminate the tissues. The transfer factors translate the exchanges between bone and the implanted material. The solvatation phenomenon and the electric charge equilibrium explain the transfer order of cations Mg 2+ , Ca 2+ and Sr 2+ and of the anion PO 4 3- . We have also determined these factors for the elements Ti, Cr and Ni. An original technique to study the bone bio-functionality was used. Use of phosphate derivatives labelled by 99m Tc allows obtaining information about the fixation of radioactive tracer. It was found that only after the eighth month at the implantation the neo-formed bone fixes the MDP (methyl diphosphate) labelled by 99m Tc in a similar way as in the control sample. Starting from this moment the

  1. Self-pinched transport of intense ion beams

    International Nuclear Information System (INIS)

    Ottinger, P.F.; Neri, J.M.; Stephanakis, S.J.

    1999-01-01

    Electron beams with substantial net currents have been routinely propagated in the self-pinched mode for the past two decades. However, as the physics of gas breakdown and beam neutralization is different for ion beams, previous predictions indicated insufficient net current for pinching so that ion beam self-pinched transport (SPT) was assumed impossible. Nevertheless, recent numerical simulations using the IPROP code have suggested that ion SPT is possible. These results have prompted initial experiments to investigate SPT of ion beams. A 100-kA, 1.2-MeV, 3-cm-radius proton beam, generated on the Gamble II pulsed-power accelerator at NRL, has been injected into helium in the 30- to 250-mTorr regime to study this phenomenon. Evidence of self-pinched ion beam transport was observed in the 35- to 80-mTorr SPT pressure window predicted by IPROP. Measured signals from a time- and space-resolved scattered proton diagnostic and a time-integrated Li(Cu) nuclear activation diagnostic, both of which measure protons striking a 10-cm diameter target 50 cm into the transport region, are significantly larger in this pressure window than expected for ballistic transport. These results are consistent with significant self-magnetic fields and self-pinching of the ion beam. On the other hand, time-integrated signals from these same two diagnostics are consistent with ballistic transport at pressures above and below the SPT window. Interferometric electron line-density measurements, acquired during beam injection into the helium gas, show insignificant ionization below 35 mTorr, a rapidly rising ionization fraction with pressure in the SPT window, and a plateau in ionization fraction at about 2% for pressures above 80 mTorr. These and other results are consistent with the physical picture for SPT. IPROP simulations, which closely model the Gamble II experimental conditions, produce results that are in qualitative agreement with the experimental results. The advantages of SPT for

  2. Efficient modeling of reactive transport phenomena by a multispecies random walk coupled to chemical equilibrium

    International Nuclear Information System (INIS)

    Pfingsten, W.

    1996-01-01

    Safety assessments for radioactive waste repositories require a detailed knowledge of physical, chemical, hydrological, and geological processes for long time spans. In the past, individual models for hydraulics, transport, or geochemical processes were developed more or less separately to great sophistication for the individual processes. Such processes are especially important in the near field of a waste repository. Attempts have been made to couple at least two individual processes to get a more adequate description of geochemical systems. These models are called coupled codes; they couple predominantly a multicomponent transport model with a chemical reaction model. Here reactive transport is modeled by the sequentially coupled code MCOTAC that couples one-dimensional advective, dispersive, and diffusive transport with chemical equilibrium complexation and precipitation/dissolution reactions in a porous medium. Transport, described by a random walk of multispecies particles, and chemical equilibrium calculations are solved separately, coupled only by an exchange term. The modular-structured code was applied to incongruent dissolution of hydrated silicate gels, to movement of multiple solid front systems, and to an artificial, numerically difficult heterogeneous redox problem. These applications show promising features with respect to applicability to relevant problems and possibilities of extensions

  3. Thermodynamics, transport phenomena, and electrochemistry of external field-assisted nonthermal food technologies.

    Science.gov (United States)

    Misra, N N; Martynenko, Alex; Chemat, Farid; Paniwnyk, Larysa; Barba, Francisco J; Jambrak, Anet Režek

    2018-07-24

    Interest in the development and adoption of nonthermal technologies is burgeoning within the food and bioprocess industry, the associated research community, and among the consumers. This is evident from not only the success of some innovative nonthermal technologies at industrial scale, but also from the increasing number of publications dealing with these topics, a growing demand for foods processed by nonthermal technologies and use of natural ingredients. A notable feature of the nonthermal technologies such as cold plasma, electrohydrodynamic processing, pulsed electric fields, and ultrasound is the involvement of external fields, either electric or sound. Therefore, it merits to study the fundamentals of these technologies and the associated phenomenon with a unified approach. In this review, we revisit the fundamental physical and chemical phenomena governing the selected technologies, highlight similarities, and contrasts, describe few successful applications, and finally, identify the gaps in research.

  4. Fission product transport in the primary system, important phenomena, and code status

    International Nuclear Information System (INIS)

    Gieseke, J.A.; Jordan, H.; Kuhlman, M.R.

    1990-01-01

    The purpose of this paper is to identify important issues concerning the transport and deposition of radionuclides in the reactor coolant system (RCS) under accident conditions and to examine how such issues are being treated or should be treated by the various available computer codes. In general, the RCS is a very important section of the transport pathway along which radionuclides move and by which they are attenuated as they travel after being released from the fuel. The RCS can serve as a sink for radionuclides that may deposit from the gas and react with surfaces, or can serve as a repository for materials deposited from the gas which are then available for later release into the transporting gas stream. The RCS may also have thermal hydraulic conditions that foster aerosol growth by condensation or agglomeration, and may provide an environment in which gas phase or heterogeneous chemical reactions may occur

  5. Various Transport Phenomena and Modeling in a Methane Reformer Duct for PEMFCs

    International Nuclear Information System (INIS)

    Jinliang Yuan; Fuan Ren; Jinliang Yuan; Bengt Sunden

    2006-01-01

    There are various physical processes (such as mass, heat and momentum transport) integrated with catalytic chemical reactions in a methane steam reforming duct. It is often found that endothermic and exothermic reactions in the ducts are strongly coupled by heat transfer from adjacent catalytic combustion ducts. In this paper, a three-dimensional calculation method is developed to simulate and analyze steam reforming of methane, and the effects on various transport processes in a steam reforming duct. The reformer conditions such as mass balances associated with the reforming reactions and gas permeation to/from the porous catalyst layer are applied in the analysis. The predicted results are presented and discussed for a composite duct consisting of a porous catalyst reaction area, the gas flow duct and solid layers. Parametric studies are conducted and the results show that the variables, such as fuel reformer temperatures and catalyst loadings, have significant effects on the transport processes and reformer performance. (authors)

  6. Transport phenomena in the edge of Alcator C-Mod plasmas

    International Nuclear Information System (INIS)

    Terry, J.L.; Basse, N.P.; Cziegler, I.; Greenwald, M.; LaBombard, B.; Edlund, E.M.; Hughes, J.W.; Lin, L.; Lin, Y.; Porkolab, M.; Veto, B.; Wukitch, S.J.; Grulke, O.; Zweben, S.J.; Sampsell, M.

    2005-01-01

    Two aspects of edge turbulence and transport in Alcator C-Mod are explored. The quasi-coherent mode, an edge fluctuation present in Enhanced Da H-mode plasmas, is examined with regard to its role in the enhanced particle transport found in these plasmas, its in/out asymmetry, its poloidal wave number, and its radial width and location. It is shown to play a dominant role in the perpendicular particle transport. The QCM is not observed at the inboard midplane, indicating that its amplitude there is significantly smaller than on the outboard side. The peak amplitude of the QCM is found just inside the separatrix, with a radial width ≥5 mm, leading to a non-zero amplitude outside the separatrix and qualitatively consistent with its transport enhancement. Also examined are the characteristics of the intermittent convective transport, associated with 'blobs' and typically occurring in the scrape-off-layer. The blobs are qualitatively similar in L- and H-mode. When their sizes, occurrence frequencies, and magnitudes are compared, it is found that the blob size may be somewhat smaller in ELMfree H-Mode, and blob frequency is similar. A clear difference is seen in the blob magnitude in the far SOL, with ELMfree H-mode showing a smaller perturbation there than L-mode. As the Greenwald density limit is approached (n/n GW ≥0.7), blobs are seen inside the separatrix, consistent with the observation that the high cross-field transport region, normally found in the far scrape-off, penetrates the closed flux surfaces at high n/n GW . (author)

  7. Physics of gas breakdown for ion beam transport in gas

    International Nuclear Information System (INIS)

    Olson, C.L.; Poukey, J.W.; Hinshelwood, D.D.; Rose, D.V.; Hubbard, R.F.; Lampe, M.; Neri, J.M.; Ottinger, P.F.; Slinker, S.P.; Stephanakis, S.J.; Young, F.C.; Welch, D.R.

    1993-01-01

    Detailed analysis, experiments, and computer simulations are producing a new understanding of gas breakdown during intense ion beam transport in neutral gas. Charge neutralization of beam micro clumps is shown to limit the net clump potentials to a non-zero value π min , which can lead to divergence growth and axial energy spreading. At pressures approx-gt 1 Torr, plasma shielding should substantially reduce this effect Current neutralization has been studied in experiments on the GAMBLE II accelerator. The importance of fast electrons (knockons and runaways) has been established in IPROP simulations, which are in agreement with the experiments. For light ion fusion parameters with pressures approx-gt 1 Torr, very small net current fractions (much-lt 1%) appear feasible, permitting ballistic transport in gas. Self-pinched requires higher net current fractions (≥ 2%) and preliminary IPROP code results indicate that this appears achievable for small-radius intense beams in lower pressure gases (approx-gt Torr). Several self-pinched transport concepts look promising. The importance of these results for both light ion fusion and heavy ion fusion is discussed

  8. Laser field effects on the transport phenomena: Energy loss and stopping power

    International Nuclear Information System (INIS)

    Torres Silva, H.; Sakanaka, P.H.

    1990-01-01

    The energy loss method has been applied to a large variety of transport problems in optics, solid-state and fusion research. In these papers, however, the transport equations were linearized, so there are no multiphoton interaction. On the other hand, Bivona et al. (1982) [2] have shown that, for a one-component plasma, the strong field effects would be only of academic interest. On the basis of the center of mass approach [3], a generalization of the energy loss rate which is in accordance with the recent results of Arista et al. (1989) [4] is obtained. (Author)

  9. Studies of transport phenomena in tokamaks with nonstationary intervention into the discharge

    International Nuclear Information System (INIS)

    Kalmykov, S.G.

    1993-01-01

    Together with detailed plasma parameter measurements, an experimental basis is provided to deduce radial profiles of local transport coefficients, to obtain their temporal evolution in the transient phase of the discharge. The equations of heat and particle balance were used as proper instrument to perform the coefficients calculation. The majority of the experiments deals with heat transport processes in the electron component of plasma. A problem in getting ohmic heat deposit radial distribution arise with use of the electron population heat balance equation. For its solution, numerical simulation of the plasma column loop voltage based on poloidal magnetic field classical diffusion supposition was used. (L.C.J.A.)

  10. Light-induced modification of plant plasma membrane ion transport.

    Science.gov (United States)

    Marten, I; Deeken, R; Hedrich, R; Roelfsema, M R G

    2010-09-01

    Light is not only the driving force for electron and ion transport in the thylakoid membrane, but also regulates ion transport in various other membranes of plant cells. Light-dependent changes in ion transport at the plasma membrane and associated membrane potential changes have been studied intensively over the last century. These studies, with various species and cell types, revealed that apart from regulation by chloroplasts, plasma membrane transport can be controlled by phytochromes, phototropins or channel rhodopsins. In this review, we compare light-dependent plasma membrane responses of unicellular algae (Eremosphaera and Chlamydomonas), with those of a multicellular alga (Chara), liverworts (Conocephalum), mosses (Physcomitrella) and several angiosperm cell types. Light-dependent plasma membrane responses of Eremosphaera and Chara are characterised by the dominant role of K(+) channels during membrane potential changes. In most other species, the Ca(2+)-dependent activation of plasma membrane anion channels represents a general light-triggered event. Cell type-specific responses are likely to have evolved by modification of this general response or through the development of additional light-dependent signalling pathways. Future research to elucidate these light-activated signalling chains is likely to benefit from the recent identification of S-type anion channel genes and proteins capable of regulating these channels.

  11. Internal Transport Barrier Driven by Redistribution of Energetic Ions

    International Nuclear Information System (INIS)

    Wong, K.L.; Heidbrink, W.W.; Ruskov, E.; Petty, C.C.; Greenfield, C.M.; Nazikian, R.; Budny, R.

    2004-01-01

    Alfven instabilities excited by energetic ions are used as a means to reduce the central magnetic shear in a tokamak via redistribution of energetic ions. When the central magnetic shear is low enough, ballooning modes become stable for any plasma pressure gradient and an internal transport barrier (ITB) with a steep pressure gradient can exist. This mechanism can sustain a steady-state ITB as demonstrated by experimental data from the DIII-D tokamak. It can also produce a shear in toroidal and poloidal plasma rotation. Possible application of this technique to use the energetic alpha particles for improvement of burning plasma performance is discussed

  12. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation

    International Nuclear Information System (INIS)

    Paszkuta, M.

    2005-06-01

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  13. New transport phenomena probed by dielectric spectroscopy of oxidized and non-oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Urbach, B.; Axelrod, E.; Sa' ar, A. [Racah Institute of Physics and the Center for Nanoscience and Nanotechnology, the Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2007-05-15

    Dielectric spectroscopy accompanied by infrared (IR) and photoluminescence (PL) spectroscopy have been utilized to reveal the correlation between transport, optical and structural properties of oxidized porous silicon (PS). Three relaxation processes at low-, mid- and high-temperatures were observed, including dc-conductivity at high-temperatures. Both the low-T relaxation and the dc conductivity were found to be thermally activated processes that involve tunneling and hopping in between the nanocrystals in oxidized PS. We have found that the dc-conductivity is limited by geometrical constrictions along the transport channels, which are not effected by the oxidation process and are characterized by activation energies of about {proportional_to}0.85 eV. The low-T relaxation process involves thermal activation followed by tunneling in between neighbor nanocrystals, with somewhat lower activation energies. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Shear flow effects on ion thermal transport in tokamaks

    International Nuclear Information System (INIS)

    Tajima, T.; Horton, W.; Dong, J.Q.; Kishimoto, Y.

    1995-03-01

    From various laboratory and numerical experiments, there is clear evidence that under certain conditions the presence of sheared flows in a tokamak plasma can significantly reduce the ion thermal transport. In the presence of plasma fluctuations driven by the ion temperature gradient, the flows of energy and momentum parallel and perpendicular to the magnetic field are coupled with each other. This coupling manifests itself as significant off-diagonal coupling coefficients that give rise to new terms for anomalous transport. The authors derive from the gyrokinetic equation a set of velocity moment equations that describe the interaction among plasma turbulent fluctuations, the temperature gradient, the toroidal velocity shear, and the poloidal flow in a tokamak plasma. Four coupled equations for the amplitudes of the state variables radially extended over the transport region by toroidicity induced coupling are derived. The equations show bifurcations from the low confinement mode without sheared flows to high confinement mode with substantially reduced transport due to strong shear flows. Also discussed is the reduced version with three state variables. In the presence of sheared flows, the radially extended coupled toroidal modes driven by the ion temperature gradient disintegrate into smaller, less elongated vortices. Such a transition to smaller spatial correlation lengths changes the transport from Bohm-like to gyrobohm-like. The properties of these equations are analyzed. The conditions for the improved confined regime are obtained as a function of the momentum-energy deposition rates and profiles. The appearance of a transport barrier is a consequence of the present theory

  15. Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2014-01-01

    Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport i...

  16. COMSOL-PHREEQC: a tool for high performance numerical simulation of reactive transport phenomena

    International Nuclear Information System (INIS)

    Nardi, Albert; Vries, Luis Manuel de; Trinchero, Paolo; Idiart, Andres; Molinero, Jorge

    2012-01-01

    Document available in extended abstract form only. Comsol Multiphysics (COMSOL, from now on) is a powerful Finite Element software environment for the modelling and simulation of a large number of physics-based systems. The user can apply variables, expressions or numbers directly to solid and fluid domains, boundaries, edges and points, independently of the computational mesh. COMSOL then internally compiles a set of equations representing the entire model. The availability of extremely powerful pre and post processors makes COMSOL a numerical platform well known and extensively used in many branches of sciences and engineering. On the other hand, PHREEQC is a freely available computer program for simulating chemical reactions and transport processes in aqueous systems. It is perhaps the most widely used geochemical code in the scientific community and is openly distributed. The program is based on equilibrium chemistry of aqueous solutions interacting with minerals, gases, solid solutions, exchangers, and sorption surfaces, but also includes the capability to model kinetic reactions with rate equations that are user-specified in a very flexible way by means of Basic statements directly written in the input file. Here we present COMSOL-PHREEQC, a software interface able to communicate and couple these two powerful simulators by means of a Java interface. The methodology is based on Sequential Non Iterative Approach (SNIA), where PHREEQC is compiled as a dynamic subroutine (iPhreeqc) that is called by the interface to solve the geochemical system at every element of the finite element mesh of COMSOL. The numerical tool has been extensively verified by comparison with computed results of 1D, 2D and 3D benchmark examples solved with other reactive transport simulators. COMSOL-PHREEQC is parallelized so that CPU time can be highly optimized in multi-core processors or clusters. Then, fully 3D detailed reactive transport problems can be readily simulated by means of

  17. Development of particle and heavy ion transport code system

    International Nuclear Information System (INIS)

    Niita, Koji

    2004-01-01

    Particle and heavy ion transport code system (PHITS) is 3 dimension general purpose Monte Carlo simulation codes for description of transport and reaction of particle and heavy ion in materials. It is developed on the basis of NMTC/JAM for design and safety of J-PARC. What is PHITS, it's physical process, physical models and development process of PHITC code are described. For examples of application, evaluation of neutron optics, cancer treatment by heavy particle ray and cosmic radiation are stated. JAM and JQMD model are used as the physical model. Neutron motion in six polar magnetic field and gravitational field, PHITC simulation of trace of C 12 beam and secondary neutron track of small model of cancer treatment device in HIMAC and neutron flux in Space Shuttle are explained. (S.Y.)

  18. Feed gas contaminant control in ion transport membrane systems

    Science.gov (United States)

    Carolan, Michael Francis [Allentown, PA; Minford, Eric [Laurys Station, PA; Waldron, William Emil [Whitehall, PA

    2009-07-07

    Ion transport membrane oxidation system comprising an enclosure having an interior and an interior surface, inlet piping having an internal surface and adapted to introduce a heated feed gas into the interior of the enclosure, and outlet piping adapted to withdraw a product gas from the interior of the enclosure; one or more planar ion transport membrane modules disposed in the interior of the enclosure, each membrane module comprising mixed metal oxide material; and a preheater adapted to heat a feed gas to provide the heated feed gas to the inlet piping, wherein the preheater comprises an interior surface. Any of the interior surfaces of the enclosure, the inlet piping, and the preheater may be lined with a copper-containing metal lining. Alternatively, any of the interior surfaces of the inlet piping and the preheater may be lined with a copper-containing metal lining and the enclosure may comprise copper.

  19. Transport of radioactive ions in soil by electrokinetics

    International Nuclear Information System (INIS)

    Buehler, M.F.; Surma, J.E.; Virden, J.W.

    1994-10-01

    An electrokinetic approach is being evaluated for in situ soil remediation at the Hanford Site in Richland, Washington. This approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The work discussed in this paper involves the development of a new method to monitor the movement of the radioactive ions within the soil during the electrokinetic process. A closed cell and a gamma counter were used to provide iii situ measurements of 137 Cs and 60 Co movement in Hanford soil. Preliminary results show that for an applied potential of 200 V over approximately 200 hr, 137 Cs and 60 60 were transported a distance of 4 to 5 in. The monitoring technique demonstrated the feasibility of using electrokinetics for soil separation applications

  20. Object oriented programming in simulation of ions transport

    International Nuclear Information System (INIS)

    Zhang Wenyong; Wang Tongquan; Xiao Yabin; Dai Hongyi; Chen Yuzhong

    2001-01-01

    Using Object Oriented Programming (OOP) method can make our program more reliable and easier to read, debug, maintain and upgrade. This paper compared FORTRAN90-the language widely used in science computing with C ++ --An Object Oriented Language, and the conclusion was made that although FORTRAN90 have many deficiencies, it can be used in Object Oriented programming. Then OOP method was used in programming of Monte Carlo simulation of ions transport and the general process of OOP was given

  1. Transient transport phenomena induced by cold pulses in W7-AS

    International Nuclear Information System (INIS)

    Walter, H.; Stroth, U.; Bleuel, J.; Burhenn, R.; Geist, T.; Giannone, L.; Hartfuss, H.; Koponen, J.P.T.; Ledl, L.; Pereverzev, G.

    1998-01-01

    Cold-pulse experiments were carried out in the W7-AS stellarator for the first time. Carbon was injected by a laser blow-off system into the plasma edge. The electron density increase due to the injected carbon is found to be responsible for the edge electron temperature drop. In all cases, the propagation of the edge temperature perturbation to the plasma centre could be modelled with a local parameter-dependent electron heat diffusivity. Unlike in tokamaks, non-local transport effects were not observed in these experiments. (author)

  2. Transient transport phenomena induced by cold pulses in W7-AS

    Energy Technology Data Exchange (ETDEWEB)

    Walter, H; Stroth, U; Bleuel, J; Burhenn, R; Geist, T; Giannone, L.; Hartfuss, H; Koponen, J P.T.; Ledl, L; Pereverzev, G [Max-Planck-Institut fuer Plasmaphysik, EURATOM-IPP Association, 85748 Garching (Germany)

    1998-09-01

    Cold-pulse experiments were carried out in the W7-AS stellarator for the first time. Carbon was injected by a laser blow-off system into the plasma edge. The electron density increase due to the injected carbon is found to be responsible for the edge electron temperature drop. In all cases, the propagation of the edge temperature perturbation to the plasma centre could be modelled with a local parameter-dependent electron heat diffusivity. Unlike in tokamaks, non-local transport effects were not observed in these experiments. (author)

  3. About relaxation phenomena and transport processing in a fully ionized non-ideal plasma

    International Nuclear Information System (INIS)

    Baimbetov, F.B.; Iztleuov, N.T.

    1999-01-01

    In this report correlation effects for non-ideal plasma are accounted in the so called pseudopotentials. The accounting of high order correlation influences in the pseudopotential lead to the strongly screened potential. Kinetic equation with pseudopotential is cited. The equations which describe the relaxation of the difference of directed velocities of plasma particles, and frequency of particle collision which determines relaxation of temperature for non-ideal plasma are obtained. On basis of mentioned kinetic equation the transport equation is obtained as well

  4. Novel phenomena in one-dimensional non-linear transport in long quantum wires

    International Nuclear Information System (INIS)

    Morimoto, T; Hemmi, M; Naito, R; Tsubaki, K; Park, J-S; Aoki, N; Bird, J P; Ochiai, Y

    2006-01-01

    We have investigated the non-linear transport properties of split-gate quantum wires of various channel lengths. In this report, we present results on a resonant enhancement of the non-linear conductance that is observed near pinch-off under a finite source-drain bias voltage. The resonant phenomenon exhibits a strong dependence on temperature and in-plane magnetic field. We discuss the possible relationship of this phenomenon to the spin-polarized manybody state that has recently been suggested to occur in quasi-one dimensional systems

  5. Intestinal ion transport in rats with spontaneous arterial hypertension.

    Science.gov (United States)

    Lübcke, R; Barbezat, G O

    1988-08-01

    1. Ion balance, intestinal ion transport in vivo with luminal Ringer, and direct voltage clamping in vivo with luminal Ringer and sodium-free choline-Ringer were studied in young (40 days old) and adult (120 days old) spontaneously hypertensive rats (SHR) and age-matched normotensive controls (Wistar-Kyoto rats, WKY). 2. Faecal sodium output was significantly higher in SHR compared with WKY in both young (+67%) and adult (+43%) rats. 3. Small-intestinal sodium absorption was equal in young SHR and WKY, but significantly greater net sodium absorption was found in the ileum of adult SHR. In contrast, net sodium absorption was reduced from the colon of both young and adult SHR. 4. In adult SHR, the colonic transepithelial short-circuit current (Isc) and the transepithelial potential difference (PD) were significantly higher, whereas the transepithelial membrane resistance (Rm) was significantly lower than in WKY. There was an identical drop in Isc in both strains when luminal sodium was replaced by choline. These data cannot be explained by increased electrogenic cation (sodium) absorption in the SHR, but would favour chloride secretion. 5. It is suggested that in SHR membrane electrolyte transport abnormalities may also be present in the epithelial cells of the small and large intestine, as have been demonstrated already in blood cells by several investigators. The SHR may become an interesting experimental animal model for the study of generalized ion transport disorders.

  6. High current transport experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    L. R. Prost

    2005-02-01

    Full Text Available The High Current Experiment at Lawrence Berkeley National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2  μC/m over long pulse durations (4  μs in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K^{+} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (≈80% is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  7. An Equation-Type Approach for the Numerical Solution of the Partial Differential Equations Governing Transport Phenomena in Porous Media

    KAUST Repository

    Sun, Shuyu; Salama, Amgad; El-Amin, Mohamed

    2012-01-01

    A new technique for the numerical solution of the partial differential equations governing transport phenomena in porous media is introduced. In this technique, the governing equations as depicted from the physics of the problem are used without extra manipulations. In other words, there is no need to reduce the number of governing equations by some sort of mathematical manipulations. This technique enables the separation of the physics part of the problem and the solver part, which makes coding more robust and could be used in several other applications with little or no modifications (e.g., multi-phase flow in porous media). In this method, one abandons the need to construct the coefficient matrix for the pressure equation. Alternatively, the coefficients are automatically generated within the solver routine. We show examples of using this technique to solving several flow problems in porous media.

  8. An Equation-Type Approach for the Numerical Solution of the Partial Differential Equations Governing Transport Phenomena in Porous Media

    KAUST Repository

    Sun, Shuyu

    2012-06-02

    A new technique for the numerical solution of the partial differential equations governing transport phenomena in porous media is introduced. In this technique, the governing equations as depicted from the physics of the problem are used without extra manipulations. In other words, there is no need to reduce the number of governing equations by some sort of mathematical manipulations. This technique enables the separation of the physics part of the problem and the solver part, which makes coding more robust and could be used in several other applications with little or no modifications (e.g., multi-phase flow in porous media). In this method, one abandons the need to construct the coefficient matrix for the pressure equation. Alternatively, the coefficients are automatically generated within the solver routine. We show examples of using this technique to solving several flow problems in porous media.

  9. Modelling the transport phenomena and texture changes of chicken breast meat during the roasting in a convective oven

    DEFF Research Database (Denmark)

    Rabeler, Felix; Feyissa, Aberham Hailu

    2018-01-01

    A numerical 3D model of coupled transport phenomena and texture changes during the roasting of chicken breast meat in a convection oven was developed. The model is based on heat and mass transfer coupled with the kinetics of temperature induced texture changes of chicken breast meat. The partial...... experimentally values. The developed model enables the prediction of the texture development inside the chicken meat as function of the process parameters. The model predictions and measured values show the clear effect of changing process settings on the texture profiles during the roasting process. Overall......, the developed model provides deep insights into the local and spatial texture changes of chicken breast meat during the roasting process that cannot be gained by experimentation alone....

  10. Transient analysis of carbon monoxide transport phenomena and adsorption kinetics in HT-PEMFC during dynamic current extraction

    International Nuclear Information System (INIS)

    Raj, Kamal Abdul Rasheedj; Chan, Siew Hwa

    2015-01-01

    Highlights: • Increasing the fuel cell temperature reduces outlet CO concentration. • Increasing the CO inlet (initial) concentration increases outlet CO concentration. • Increasing current density step and dwell time increases outlet CO concentration. • Increasing in the CL and GDL porosities reduces outlet CO concentration. - Abstract: This paper investigates the transport phenomena of carbon monoxide (CO) and adsorption kinetics, in a high-temperature proton exchange membrane fuel cell (HT-PEMFC) during step-wise current extraction (step-change in current extraction). Step-wise current extraction is a common process done to accommodate a sudden power surge during an operation. Since HT-PEMFCs are capable of handling high impurity of CO, hydrogen fuel that is contaminated with trace amount of CO is usually considered for commercial benefits. Thus, a transient three-dimensional isothermal anodic electro-kinetic numerical model is developed to determine the effect of operating parameters such as fuel cell temperature, CO inlet (initial) concentration, step-change of current density and dwell time on the transport phenomena of CO and adsorption kinetics. In addition, geometrical factors such as the catalyst layer (CL) and gas diffusion layer (GDL) porosity are also varied as well. The results show that the above-mentioned operating parameters can affect the maximum CO concentration at the CL, especially at the outlet of the channel. Specifically, a reduction of fuel cell temperature can significantly increase the CO concentration near the outlet, while increasing CO inlet (initial) concentration, step-change amplitude of current density and current density dwell time can cause an increase in CO concentration at the outlet, albeit to different extent. In addition, the increase in the porosity of CL and GDL, results in the reduction of the maximum CO concentration at the outlet, albeit to different extent. In addition, the CO and hydrogen surface coverage

  11. Transport of energetic ions by low-n magnetic perturbations

    International Nuclear Information System (INIS)

    Mynick, H.E.

    1992-10-01

    The stochastic transport of MeV ions induced by low-n magnetic perturbations is studied, focussing chiefly on the stochastic mechanism operative for passing particles in low frequency perturbations. Beginning with a single-harmonic form for the perturbing field, it iii first shown numerically and analytically that the stochastic threshold of energetic particles can be much lower than that of the magnetic field, contrary to earlier expectations, so that MHD perturbations could cause appreciable loss of energetic ions without destroying the bulk confinement. The analytic theory is then extended in a number of directions, to darity the relation of the present stochaistic mechanism to instances already found, to allow for more complex perturbations, and to consider the more general relationship between the stochasticity of magnetic fields, and that of particles of differing energies (and pitch angles) moving in those fields. It is shown that the stochastic threshold is in general a nonmonotonic function of energy, whose form can to some extent be tailored to achieve desired goals (e.g., burn control or ash removal) by a judicious choice of the perturbation. Illustrative perturbations are exhibited which are stochastic for low but not for high-energy ions, for high but not for low-energy ions, and for intermediate-energy ions, but not for low or high energy. The second possibility is the behavior needed for burn control; the third provides a possible mechanism for ash removal

  12. Imaging transport phenomena during lysozyme protein crystal growth by the hanging drop technique

    Science.gov (United States)

    Sethia Gupta, Anamika; Gupta, Rajive; Panigrahi, P. K.; Muralidhar, K.

    2013-06-01

    The present study reports the transport process that occurs during the growth of lysozyme protein crystals by the hanging drop technique. A rainbow schlieren technique has been employed for imaging changes in salt concentration. A one dimensional color filter is used to record the deflection of the light beam. An optical microscope and an X-ray crystallography unit are used to characterize the size, tetragonal shape and Bravais lattice constants of the grown crystals. A parametric study on the effect of drop composition, drop size, reservoir height and number of drops on the crystal size and quality is reported. Changes in refractive index are not large enough to create a meaningful schlieren image in the air gap between the drop and the reservoir. However, condensation of fresh water over the reservoir solution creates large changes in the concentration of NaCl, giving rise to clear color patterns in the schlieren images. These have been analyzed to obtain salt concentration profiles near the free surface of the reservoir solution as a function of time. The diffusion of fresh water into the reservoir solution at the early stages of crystal growth followed by the mass flux of salt from the bulk solution towards the free surface has been recorded. The overall crystal growth process can be classified into two regimes, as demarcated by the changes in slope of salt concentration within the reservoir. The salt concentration in the reservoir equilibrates at long times when the crystallization process is complete. Thus, transport processes in the reservoir emerge as the route to monitor protein crystal growth in the hanging drop configuration. Results show that crystal growth rate is faster for a higher lysozyme concentration, smaller drops, and larger reservoir heights.

  13. Simulations of phenomena related to edge transport in tokamak fusion plasmas

    International Nuclear Information System (INIS)

    Konzett, S.

    2011-01-01

    This thesis investigates turbulence in a tokamak fusion plasma using numerical simulations. The fluid turbulence code ATTEMPT, which computes the drift dynamics of ions and electrons in electromagnetic fields, is applied to investigate three physical effects which are motivated by recent experimental findings. The first part shows that the statistics of drift fluid turbulence are largely unaffected by the presence of rational magnetic surfaces for typical edge parameter regimes. The second part contains an analysis of the dependence of correlation lengths on various physical parameters. A systematic approach reveals the impact of plasma parameters - which change in the transition from L to H-mode - on parallel, radial and perpendicular correlation lengths. In the last part of the thesis a new flux surface geometry is implemented in the ATTEMPT code. The modified geometry models the onset of the change in magnetic topology near a magnetic X-point. Computations show that turbulent fluctuations are reduced in an X-point distorted flux surface geometry, and the spectral structure of turbulence is altered substantially. (author) [de

  14. Computational simulation of lithium ion transport through polymer nanocomposite membranes

    International Nuclear Information System (INIS)

    Moon, P.; Sandi, G.; Kizilel, R.; Stevens, D.

    2003-01-01

    We think of membranes as simple devices to facilitate filtration. In fact, membranes play a role in chemical, biological, and engineering processes such as catalysis, separation, and sensing by control of molecular transport and recognition. Critical factors that influence membrane discrimination properties include composition, pore size (as well as homogeneity), chemical functionalization, and electrical transport properties. There is increasing interest in using nanomaterials for the production of novel membranes due to the unique selectivity that can be achieved. Clay-polymer nanocomposites show particular promise due to their ease of manufacture (large sheets), their rigidity (self supporting), and their excellent mechanical properties. However, the process of lithium ion transport through the clay-polymer nanocomposite and mechanisms of pore size selection are poorly understood at the ionic and molecular level. In addition, manufacturing of clay-polymer nanocomposite membranes with desirable properties has proved challenging. We have built a general membrane-modeling tool (simulation system) to assist in developing improved membranes for selection, electromigration, and other electrochemical applications. Of particular interest are the recently formulated clay-polymer membranes. The transport mechanisms of the lithium ions membranes are not well understood and, therefore, they make an interesting test case for the model. In order to validate the model, we synthesized polymer nanocomposites membranes.

  15. Ion Transport through Diffusion Layer Controlled by Charge Mosaic Membrane

    Directory of Open Access Journals (Sweden)

    Akira Yamauchi

    2012-01-01

    Full Text Available The kinetic transport behaviors in near interface of the membranes were studied using commercial anion and cation exchange membrane and charge mosaic membrane. Current-voltage curve gave the limiting current density that indicates the ceiling of conventional flux. From chronopotentiometry above the limiting current density, the transition time was estimated. The thickness of boundary layer was derived with conjunction with the conventional limiting current density and the transition time from steady state flux. On the other hand, the charge mosaic membrane was introduced in order to examine the ion transport on the membrane surface in detail. The concentration profile was discussed by the kinetic transport number with regard to the water dissociation (splitting on the membrane surface.

  16. Mass transport of heavy metal ions and radon in gels used as sealing agents in containment technologies

    International Nuclear Information System (INIS)

    Lakatos, I.; Bauer, K.; Lakatos-Szabo, J.; Kretzschmar, H.J.

    1997-01-01

    The diffusion and hydrodynamic mass transport of multivalent cations, mostly Cr(III) and Cr(VI) ions and radon in polymer/silicate gels and Montanwax emulsions were studied. It was concluded that the self-conforming gels may decrease the hydrodynamic mass transport in porous and fractured media by 4-6 orders of magnitude. In water saturated systems, however, the diffusion transport can be restricted by hydrogels only to a moderate extent. On the other hand, the high and selective retention capacity of gels towards different diffusing species may open new vistas in the sealing technologies. Similar results were obtained for transport phenomena of radon. The almost perfect quenching process of radon and its nuclides in gels and emulsions further enhances the positive effects of the encapsulation methods. The laboratory experiments provided valuable new information to design the different containment technologies

  17. Mass transport of heavy metal ions and radon in gels used as sealing agents in containment technologies

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, I.; Bauer, K.; Lakatos-Szabo, J. [Research Lab. for Mining Chemistry, Miskolc-Egyetemvaros (Hungary); Kretzschmar, H.J. [DBI Gas- und Umwelttechnik GmbH, Feiberg (Germany)

    1997-12-31

    The diffusion and hydrodynamic mass transport of multivalent cations, mostly Cr(III) and Cr(VI) ions and radon in polymer/silicate gels and Montanwax emulsions were studied. It was concluded that the self-conforming gels may decrease the hydrodynamic mass transport in porous and fractured media by 4-6 orders of magnitude. In water saturated systems, however, the diffusion transport can be restricted by hydrogels only to a moderate extent. On the other hand, the high and selective retention capacity of gels towards different diffusing species may open new vistas in the sealing technologies. Similar results were obtained for transport phenomena of radon. The almost perfect quenching process of radon and its nuclides in gels and emulsions further enhances the positive effects of the encapsulation methods. The laboratory experiments provided valuable new information to design the different containment technologies.

  18. Silicon based nanogap device for studying electrical transport phenomena in molecule-nanoparticle hybrids

    International Nuclear Information System (INIS)

    Strobel, Sebastian; Hernandez, Rocio Murcia; Hansen, Allan G; Tornow, Marc

    2008-01-01

    We report the fabrication and characterization of vertical nanogap electrode devices using silicon-on-insulator substrates. Using only standard silicon microelectronic process technology, nanogaps down to 26 nm electrode separation were prepared. Transmission electron microscopy cross-sectional analysis revealed the well defined material architecture of the nanogap, comprising two electrodes of dissimilar geometrical shape. This asymmetry is directly reflected in transport measurements on molecule-nanoparticle hybrid systems formed by self-assembling a monolayer of mercaptohexanol on the electrode surface and the subsequent dielectrophoretic trapping of 30 nm diameter Au nanoparticles. The observed Coulomb staircase I-V characteristic measured at T = 4.2 K is in excellent agreement with theoretical modelling, whereby junction capacitances of the order of a few 10 -18 farad and asymmetric resistances of 30 and 300 MΩ, respectively, are also supported well by our independent estimates for the formed double barrier tunnelling system. We propose our nanoelectrode system for integrating novel functional electronic devices such as molecular junctions or nanoparticle hybrids into existing silicon microelectronic process technology

  19. Investigations into co-transport phenomena in PUREX relevant solutions by use of an analytical ultracentrifuge

    International Nuclear Information System (INIS)

    Gauglitz, R.; Marx, G.

    1991-01-01

    The diffusion of the elements uranium, neodymium, chromium, iron, ruthenium was studied in aqueous and aqueous nitric acid solutions. The diffusion of these elements was measured not only under a concentration gradient but also with respect to simultanious nitric and diffusion. Measurements with schlierenoptics and with uv/vis.-optic were carried out at the same time. Besides the diffusion of metal nitrates and potassium dichromate also nitric acid diffusion was investigated. Also in this case apparent diffusion coefficients were determined under concentration gradients and under the influence of superposing element gradients. The diffusion of the elements uranium, neodymium, ruthenium, neptunium and plutonium was also determined in organic systems. At first the transport of the elements was measured under an element gradient, in presence of various amounts of water and nitric acid. These experiments were followed by those on simultanious diffusion of water of nitric acid and elements in TBP/dodecane mixture. Furthermore TBP/dodecane solutions were oxidized with potassium dichromate. This oxidation was measured using a gaschromatograph. From the obtained results the formation rate for the oxidation products could be calculated which proved that higher nitric acid concentrations increased the rate. (orig.) With 16 refs., 100 tabs., 120 figs [de

  20. Transport phenomena in the cathode of a molten carbonate fuel cell

    International Nuclear Information System (INIS)

    Berg, P.; Findlay, J.

    2009-01-01

    'Full text': A Molten Carbonate Fuel Cell (MCFC) is an electro-chemical energy conversion technology that runs on natural gas and employs a molten salt electrolyte. In order to keep the electrolyte in this state, the cell must be kept at a temperature above 500 C, eliminating the need for noble catalysts. There has been only a limited amount of research on modelling the transport processes inside this device, mainly due to its limited ability for mobile applications. A model for the reaction-diffusion processes within the cathode of a MCFC is developed using Fick's Law for diffusion and incorporating Darcy's Law for convection. A model for Binary Diffusion is also discussed and compared to those for Fickian diffusion. It can be shown that there exists a limiting case for diffusion across the cathode that depends on the conductivity for the liquid potential, for which there exists an analytical solution. Results are also discussed for varying diffusivities and permeabilities. Ultimately, this research focuses on the optimization of the electrode porosity to increase the power output of the fuel cell. The porosity is considered as a function of position, and is optimized using the software package MATLAB. (author)

  1. Forty years of 9Sr in situ migration: importance of soil characterization in modeling transport phenomena

    International Nuclear Information System (INIS)

    Fernandez, J.M.; Piault, E.; Macouillard, D.; Juncos, C.

    2006-01-01

    In 1960 experiments were carried out on the transfer of 9 Sr between soil, grapes and wine. The experiments were conducted in situ on a piece of land limited by two control strips. The 9 Sr migration over the last 40 years was studied by performing radiological and physico-chemical characterizations of the soil on eight 70 cm deep cores. The vertical migration modeling of 9 Sr required the definition of a triple layer conceptual model integrating the rainwater infiltration at constant flux as the only external factor of influence. Afterwards the importance of a detailed soil characterization for modeling was discussed and satisfactory simulation of the 9 Sr vertical transport was obtained and showed a calculated migration rate of about 1.0 cm year -1 in full agreement with the in situ measured values. The discussion was regarding some of the key parameters such as granulometry, organic matter content (in the Van Genuchten parameter determination), Kd and the efficient rainwater infiltration. Besides the experimental data, simplifying assumptions in modeling such as water-soil redistribution calculation and factual discontinuities in conceptual model were examined

  2. Silicon based nanogap device for studying electrical transport phenomena in molecule-nanoparticle hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Strobel, Sebastian; Hernandez, Rocio Murcia [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany); Hansen, Allan G; Tornow, Marc [Institut fuer Halbleitertechnik, Technische Universitaet Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany)], E-mail: m.tornow@tu-bs.de

    2008-09-17

    We report the fabrication and characterization of vertical nanogap electrode devices using silicon-on-insulator substrates. Using only standard silicon microelectronic process technology, nanogaps down to 26 nm electrode separation were prepared. Transmission electron microscopy cross-sectional analysis revealed the well defined material architecture of the nanogap, comprising two electrodes of dissimilar geometrical shape. This asymmetry is directly reflected in transport measurements on molecule-nanoparticle hybrid systems formed by self-assembling a monolayer of mercaptohexanol on the electrode surface and the subsequent dielectrophoretic trapping of 30 nm diameter Au nanoparticles. The observed Coulomb staircase I-V characteristic measured at T = 4.2 K is in excellent agreement with theoretical modelling, whereby junction capacitances of the order of a few 10{sup -18} farad and asymmetric resistances of 30 and 300 M{omega}, respectively, are also supported well by our independent estimates for the formed double barrier tunnelling system. We propose our nanoelectrode system for integrating novel functional electronic devices such as molecular junctions or nanoparticle hybrids into existing silicon microelectronic process technology.

  3. Silicon based nanogap device for studying electrical transport phenomena in molecule-nanoparticle hybrids.

    Science.gov (United States)

    Strobel, Sebastian; Hernández, Rocío Murcia; Hansen, Allan G; Tornow, Marc

    2008-09-17

    We report the fabrication and characterization of vertical nanogap electrode devices using silicon-on-insulator substrates. Using only standard silicon microelectronic process technology, nanogaps down to 26 nm electrode separation were prepared. Transmission electron microscopy cross-sectional analysis revealed the well defined material architecture of the nanogap, comprising two electrodes of dissimilar geometrical shape. This asymmetry is directly reflected in transport measurements on molecule-nanoparticle hybrid systems formed by self-assembling a monolayer of mercaptohexanol on the electrode surface and the subsequent dielectrophoretic trapping of 30 nm diameter Au nanoparticles. The observed Coulomb staircase I-V characteristic measured at T = 4.2 K is in excellent agreement with theoretical modelling, whereby junction capacitances of the order of a few 10(-18) farad and asymmetric resistances of 30 and 300 MΩ, respectively, are also supported well by our independent estimates for the formed double barrier tunnelling system. We propose our nanoelectrode system for integrating novel functional electronic devices such as molecular junctions or nanoparticle hybrids into existing silicon microelectronic process technology.

  4. Spectroscopic imaging studies of nanoscale polarity and mass transport phenomena in self-assembled organic nanotubes.

    Science.gov (United States)

    Xu, Hao; Nagasaka, Shinobu; Kameta, Naohiro; Masuda, Mitsutoshi; Ito, Takashi; Higgins, Daniel A

    2017-08-02

    Synthetic organic nanotubes self-assembled from bolaamphiphile surfactants are now being explored for use as drug delivery vehicles. In this work, several factors important to their implementation in drug delivery are explored. All experiments are performed with the nanotubes immersed in ethanol. First, Nile Red (NR) and a hydroxylated Nile Red derivative (NR-OH) are loaded into the nanotubes and spectroscopic fluorescence imaging methods are used to determine the apparent dielectric constant of their local environment. Both are found in relatively nonpolar environments, with the NR-OH molecules preferring regions of relatively higher dielectric constant compared to NR. Unique two-color imaging fluorescence correlation spectroscopy (imaging FCS) measurements are then used along with the spectroscopic imaging results to deduce the dielectric properties of the environments sensed by mobile and immobile populations of probe molecules. The results reveal that mobile NR molecules pass through less polar regions, likely within the nanotube walls, while immobile NR molecules are found in more polar regions, possibly near the nanotube surfaces. In contrast, mobile and immobile NR-OH molecules are found to locate in environments of similar polarity. The imaging FCS results also provide quantitative data on the apparent diffusion coefficient for each dye. The mean diffusion coefficient for the NR dye was approximately two-fold larger than that of NR-OH. Slower diffusion by the latter could result from its additional hydrogen bonding interactions with polar triglycine, amine, and glucose moieties near the nanotube surfaces. The knowledge gained in these studies will allow for the development of nanotubes that are better engineered for applications in the controlled transport and release of uncharged, dipolar drug molecules.

  5. Current neutralization in ballistic transport of light ion beams

    International Nuclear Information System (INIS)

    Hubbard, R.F.; Slinker, S.P.; Lampe, M.; Joyce, G.; Ottinger, P.

    1992-01-01

    Intense light ion beams are being considered as drivers to ignite fusion targets in the Laboratory Microfusion Facility (LMF). Ballistic transport of these beams from the diode to the target is possible only if the beam current is almost completely neutralized by plasma currents. This paper summarizes related work on relativistic electron beam and heavy ion beam propagation and describes a simple simulation model (DYNAPROP) which has been modified to treat light ion beam propagation. DYNAPROP uses an envelope equation to treat beam dynamics and uses rate equations to describe plasma and conductivity generation. The model has been applied both to the high current, 30 MeV Li +3 beams for LMF as well as low current, 1.2 MeV proton beams which are currently being studied on GAMBLE B at the Naval Research Laboratory. The predicted ratio of net currents to beam current is ∼0.1--0.2 for the GAMBLE experiment and ∼0.01 for LMF. The implications of these results for LMF and the GAMBLE experiments art discussed in some detail. The simple resistive model in DYNAPROP has well-known limitations in the 1 torr regime which arise primarily from the neglect of plasma electron transport. Alternative methods for treating the plasma response are discussed

  6. Particle modeling of transport of α-ray generated ion clusters in air

    International Nuclear Information System (INIS)

    Tong, Lizhu; Nanbu, Kenichi; Hirata, Yosuke; Izumi, Mikio; Miyamoto, Yasuaki; Yamaguchi, Hiromi

    2006-01-01

    A particle model is developed using the test-particle Monte Carlo method to study the transport properties of α-ray generated ion clusters in a flow of air. An efficient ion-molecule collision model is proposed to simulate the collisions between ion and air molecule. The simulations are performed for a steady state of ion transport in a circular pipe. In the steady state, generation of ions is balanced with such losses of ions as absorption of the measuring sensor or pipe wall and disappearance by positive-negative ion recombination. The calculated ion current to the measuring sensor agrees well with the previous measured data. (author)

  7. An entropic approach to magnetized nonlocal transport and other kinetic phenomena in high-energy-density plasmas

    International Nuclear Information System (INIS)

    Del-Sorbo, Dario

    2015-01-01

    Hydrodynamic simulations in high-energy-density physics and inertial confinement fusion require a detailed description of energy fluxes. The leading mechanism is the electron transport, which can be a nonlocal phenomenon that needs to be described with quasistationary and simplified Fokker-Planck models in large scale hydrodynamic codes. My thesis is dedicated to the development of a new nonlocal transport model based on a fast-moving-particles collision operator and on a first moment Fokker-Planck equation, simplified with an entropic closure relation. Such a closure enables a better description of the electron distribution function in the limit of high anisotropies, where small scale electrostatic instabilities could be excited. This new model, so called M1, is successfully compared with the well known nonlocal electron transport model proposed by Schurtz, Nicolai and Busquet, using different collision operators, and with the reduced Fokker-Planck model, based on a small-anisotropies polynomial closure relation (P1). Several typical configurations of heat transport are considered. We show that the M1 entropic model may operate in two and three dimensions and is able to account for electron transport modifications in external magnetic fields. Moreover, our model enables to compute realistic electron distribution functions, which can be used for kinetic studies, as for the plasma stability in the transport zone. It is demonstrated that the electron energy transport may strongly modify damping of Langmuir and ion acoustic waves, while the simplified nonlocal transport models are not able to describe accurately the modifications of the distribution function and plasma wave damping. The structure of the M1 model allows to naturally take into account self-generated magnetic fields, which play a crucial role in multidimensional simulations. Moreover, magnetic fields could also be used for the focusing of energetic particles in alternative ignition schemes. The M1 model

  8. On fast-ion transport and burn control in Tokamaks

    International Nuclear Information System (INIS)

    Wising, F.

    1994-01-01

    Fast ions, generated by e.g. neutral beam injection (NBI), radio frequency (RF) heating or nuclear reactions, play an important role in all large tokamaks. Several issues related to fast ions and burning fusion plasmas are addressed in this thesis. Firstly, a new model of sawtooth oscillations is developed which explains the recent observations that q 0 remains below unity during the entire sawtooth cycle. The model features full reconnection in two current layers and provides a self-consistent description of the plasma states before and after the sawtooth crash. It is applied to the redistribution of fast NBI-ions in JET and comparisons are made with global as well as line-of-sight integrated D-D neutron measurements. Both the new model and the classical Kadomtsev model are found to be in agreement with the measurements. A simplified redistribution model is developed and applied to the redistribution of tritons and thermal ions, again giving reasonable agreement with D-T/D-D neutron measurements. Using a separate method, earlier results on expulsion of NBI-ions are confirmed. Secondly, a numerical study has been carried out of the coupled nonlinear evolution of alpha-particle driven kinetic Alfven wave turbulence and associated alpha transport. The saturated fluctuation spectrum consists of two peaks and results from nonlinear ion Compton scattering-induced transfer of energy from longer to shorter wavelengths. An analytical solution of the saturated spectrum, and estimates of the anomalous alpha diffusion coefficient, are given. The final paper addresses the problem of determining whether an initial temperature profile, established by e.g. auxiliary heating, will evolve to thermonuclear burn or quench under the influence of alpha particle heating and thermal conduction. Explicit burn criteria are presented and the beneficial effects of density and temperature peaking are discussed. 110 refs

  9. Energetic O+ and H+ Ions in the Plasma Sheet: Implications for the Transport of Ionospheric Ions

    Science.gov (United States)

    Ohtani, S.; Nose, M.; Christon, S. P.; Lui, A. T.

    2011-01-01

    The present study statistically examines the characteristics of energetic ions in the plasma sheet using the Geotail/Energetic Particle and Ion Composition data. An emphasis is placed on the O+ ions, and the characteristics of the H+ ions are used as references. The following is a summary of the results. (1) The average O+ energy is lower during solar maximum and higher during solar minimum. A similar tendency is also found for the average H+ energy, but only for geomagnetically active times; (2) The O+ -to -H+ ratios of number and energy densities are several times higher during solar maximum than during solar minimum; (3) The average H+ and O+ energies and the O+ -to -H+ ratios of number and energy densities all increase with geomagnetic activity. The differences among different solar phases not only persist but also increase with increasing geomagnetic activity; (4) Whereas the average H+ energy increases toward Earth, the average O+ energy decreases toward Earth. The average energy increases toward dusk for both the H+ and O+ ions; (5) The O+ -to -H+ ratios of number and energy densities increase toward Earth during all solar phases, but most clearly during solar maximum. These results suggest that the solar illumination enhances the ionospheric outflow more effectively with increasing geomagnetic activity and that a significant portion of the O+ ions is transported directly from the ionosphere to the near ]Earth region rather than through the distant tail.

  10. Mathematical Modeling of Transport Phenomena in Polymer Electrolyte and Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Erik

    2004-02-01

    This thesis deals with modeling of two types of fuel cells: the polymer electrolyte fuel cell (PEFC) and the direct methanol fuel cell (DMFC), for which we address four major issues: a) mass transport limitations; b) water management (PEFC); c) gas management (DMFC); d) thermal management. Four models have been derived and studied for the PEFC, focusing on the cathode. The first exploits the slenderness of the cathode for a two-dimensional geometry, leading to a reduced model, where several non dimensional parameters capture the behavior of the cathode. The model was extended to three dimensions, where four different flow distributors were studied for the cathode. A quantitative comparison shows that the interdigitated channels can sustain the highest current densities. These two models, comprising isothermal gas phase flow, limit the studies to (a). Returning to a two-dimensional geometry of the PEFC, the liquid phase was introduced via a separate flow model approach for the cathode. In addition to conservation of mass, momentum and species, the model was extended to consider simultaneous charge and heat transfer for the whole cell. Different thermal, flow fields, and hydrodynamic conditions were studied, addressing (a), (b) and (d). A scale analysis allowed for predictions of the cell performance prior to any computations. Good agreement between experiments with a segmented cell and the model was obtained. A liquid-phase model, comprising conservation of mass, momentum and species, was derived and analyzed for the anode of the DMFC. The impact of hydrodynamic, electrochemical and geometrical features on the fuel cell performance were studied, mainly focusing on (a). The slenderness of the anode allows the use of a narrow-gap approximation, leading to a reduced model, with benefits such as reduced computational cost and understanding of the physical trends prior to any numerical computations. Adding the gas-phase via a multiphase mixture approach, the gas

  11. Heavy ion transport in the core of ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Odstrcil, Tomas [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); Physik-Department E28, Technische Universitaet Muenchen, 85747 Garching (Germany); Puetterich, Thomas; Angioni, Clemente; Bilato, Roberto; Gude, Anja; Vezinet, Didier [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching (Germany); Mazon, Didier [CEA, IRFM F-13108 Saint Paul-lez-Durance (France); Collaboration: ASDEX Upgrade Team

    2016-07-01

    High impurity concentration in the core of the future fusion reactors can lead to the serious degradation of the achievable fusion gain. Therefore, a better understanding of the underlying impurity transport processes is necessary for higher performance, more efficient power exhaust and avoidance of impurity accumulation. Radial impurity transport is mainly driven by neoclassical and turbulent particle fluxes. Both these components show substantial variation depending on the poloidal angle. Consequently, an asymmetry in the poloidal distribution of impurities leads to significant changes in the radial impurity flow and the total content of the plasma core. The aim of this contribution is to experimentally verify a model describing the poloidal asymmetry of heavy impurities using measurements from ASDEX Upgrade. The observed asymmetries are caused mainly by the centrifugal force and poloidal electric force created by the fast particles produced by intensive ion-cyclotron heating. Finally, a change in the radial transport of the tungsten ions will be presented in the case of large inboard and outboard impurity accumulation.

  12. Electron and ion beam transport to fusion targets

    International Nuclear Information System (INIS)

    Freeman, J.R.; Baker, L.; Miller, P.A.; Mix, L.P.; Olsen, J.N.; Poukey, J.W.; Wright, T.P.

    1979-01-01

    ICF reactors have been proposed which incorporate a gas-filled chamber to reduce x-ray and debris loading of the first wall. Focused beams of either electrons or ions must be transported efficiently for 2-4 m to a centrally located fusion target. Laser-initiated current-carrying plasma discharge channels provide the guiding magnetic field and the charge- and current-neutralizing medium required for beam propagation. Computational studies of plasma channel formation in air using a 1-D MHD model with multigroup radiation diffusion have provided a good comparison with the expansions velocity and time dependent refractivity profile determined by holographic interferometry. Trajectory calculations have identified a beam expansion mechanism which combines with the usual ohmic dissipation to reduce somewhat the transported beam fluence for electrons. Additional trajectory calculations have been performed for both electrons and light ions to predict the limits on the particle current density which can be delivered to a central target by overlapping the many independently-generated beams. Critical features of the use of plasma channels for transport and overlap of charged particle beams are being tested experimentally with up to twelve electron beams from the Proto II accelerator

  13. Physics of electron and lithium-ion transport in electrode materials for Li-ion batteries

    International Nuclear Information System (INIS)

    Wu Musheng; Xu Bo; Ouyang Chuying

    2016-01-01

    The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries (LIBs) are briefly summarized here, besides, we review the current research on ionic and electrical conduction in electrode material incorporating experimental and simulation studies. Commercial LIBs have been widely used in portable electronic devices and are now developed for large-scale applications in hybrid electric vehicles (HEV) and stationary distributed power stations. However, due to the physical limits of the materials, the overall performance of today’s LIBs does not meet all the requirements for future applications, and the transport problem has been one of the main barriers to further improvement. The electron and Li-ion transport behaviors are important in determining the rate capacity of LIBs. (topical review)

  14. Development of general-purpose particle and heavy ion transport monte carlo code

    International Nuclear Information System (INIS)

    Iwase, Hiroshi; Nakamura, Takashi; Niita, Koji

    2002-01-01

    The high-energy particle transport code NMTC/JAM, which has been developed at JAERI, was improved for the high-energy heavy ion transport calculation by incorporating the JQMD code, the SPAR code and the Shen formula. The new NMTC/JAM named PHITS (Particle and Heavy-Ion Transport code System) is the first general-purpose heavy ion transport Monte Carlo code over the incident energies from several MeV/nucleon to several GeV/nucleon. (author)

  15. Ion turbulence and thermal transport in laser-produced plasmas

    International Nuclear Information System (INIS)

    Barr, H.C.; Boyd, T.J.M.

    1982-01-01

    In the interaction of high-intensity lasers with target plasmas the transport of thermal energy from the region in which the radiation is absorbed, to the cold dense plasma in the interior of the target, is an issue of central importance. The role of ion turbulence as a flux limiter is addressed with particular regard to recent experiments in which target plasmas were irradiated by 1.06 μm neodymium laser light at irradiances of 10 15 W cm - 2 and greater. Saturation levels of the ion-acoustic turbulence driven by a combination of a suprathermal electron current and a heat flux are calculated on the basis of perturbed orbit theory. The levels of turbulence are found to be markedly lower than those commonly estimated from simple trapping arguments and too low to explain the thermal flux inhibition observed in the experiments used as a basis for the model. (author)

  16. New Trends in Cancer Therapy: Targeting Ion Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Annarosa Arcangeli

    2010-04-01

    Full Text Available The expression and activity of different channel types mark and regulate specific stages of cancer establishment and progression. Blocking channel activity impairs the growth of some tumors, both in vitro and in vivo, which opens a new field for pharmaceutical research. However, ion channel blockers may produce serious side effects, such as cardiac arrhythmias. For instance, Kv11.1 (hERG1 channels are aberrantly expressed in several human cancers, in which they control different aspects of the neoplastic cell behaviour. hERG1 blockers tend to inhibit cancer growth. However they also retard the cardiac repolarization, thus lengthening the electrocardiographic QT interval, which can lead to life-threatening ventricular arrhythmias. Several possibilities exist to produce less harmful compounds, such as developing specific drugs that bind hERG1 channels in the open state or disassemble the ion channel/integrin complex which appears to be crucial in certain stages of neoplastic progression. The potential approaches to improve the efficacy and safety of ion channel targeting in oncology include: (1 targeting specific conformational channel states; (2 finding ever more specific inhibitors, including peptide toxins, for channel subtypes mainly expressed in well-identified tumors; (3 using specific ligands to convey traceable or cytotoxic compounds; (4 developing channel blocking antibodies; (5 designing new molecular tools to decrease channel expression in selected cancer types. Similar concepts apply to ion transporters such as the Na+/K+ pump and the Na+/H+ exchanger. Pharmacological targeting of these transporters is also currently being considered in anti-neoplastic therapy.

  17. Radioprotector modifying influence upon the ion transport ATPase activities

    International Nuclear Information System (INIS)

    Dvoretsky, A.I.; Egorova, E.G.; Ananieva, T.V.; Kulikova, I.A.

    1993-01-01

    The effects of aminothiol and biogenic amine radioprotectors (β-mercaptoethylamine, AET, serotonin, dopamine, histamine) on the basic ion transport enzymes, such as Na, K-ATP ase and Mg, Ca-ATPase activities were investigated in the tissues of numerous organs, with different radiosensitivity in the wistar rats. Experimental results showed that intraperitoneal injection of the used radioprotectors caused preliminary inhibition of the Na, K-ATPase activity in tissues from organs with different radioresistance, but had no influence on the Mg, Ca-ATPase activity in membranes of erythrocytes and rat brain cells. (2 tabs.)

  18. PHYSIOLOGY OF ION TRANSPORT ACROSS THE TONOPLAST OF HIGHER PLANTS.

    Science.gov (United States)

    Barkla, Bronwyn J.; Pantoja, Omar

    1996-06-01

    The vacuole of plant cells plays an important role in the homeostasis of the cell. It is involved in the regulation of cytoplasmic pH, sequestration of toxic ions and xenobiotics, regulation of cell turgor, storage of amino acids, sugars and CO2 in the form of malate, and possibly as a source for elevating cytoplasmic calcium. All these activities are driven by two primary active transport mechanisms present in the vacuolar membrane (tonoplast). These two mechanisms employ high-energy metabolites to pump protons into the vacuole, establishing a proton electrochemical potential that mediates the transport of a diverse range of solutes. Within the past few years, great advances at the molecular and functional levels have been made on the characterization and identification of these mechanisms. The aim of this review is to summarize these studies in the context of the physiology of the plant cell.

  19. Modeling of Flow, Transport and Controlled Sedimentation Phenomena during Mixing of Salt Solutions in Complex Porous Formations

    Science.gov (United States)

    Skouras, Eugene D.; Jaho, Sofia; Pavlakou, Efstathia I.; Sygouni, Varvara; Petsi, Anastasia; Paraskeva, Christakis A.

    2015-04-01

    The deposition of salts in porous media is a major engineering phenomenon encountered in a plethora of industrial and environmental applications where in some cases is desirable and in other not (oil production, geothermal systems, soil stabilization etc). Systematic approach of these problems requires knowledge of the key mechanisms of precipitating salts within the porous structures, in order to develop new methods to control the process. In this work, the development and the solution of spatiotemporally variable mass balances during salt solution mixing along specific pores were performed. Both analytical models and finite differences CFD models were applied for the study of flow and transport with simultaneous homogeneous and heterogeneous nucleation (by crystal growth on the surface of the pores) in simple geometries, while unstructured finite elements and meshless methods were developed and implemented for spatial discretization, reconstruction, and solution of transport equations and homogeneous / heterogeneous reactions in more complex geometries. At initial stages of this work, critical problem parameters were identified, such as the characteristics of the porosity, the number of dissolved components, etc. The parameters were then used for solving problems which correspond to available experimental data. For each combination of ions and materials, specific data and process characteristics were included: (a) crystal kinetics (nucleation, growth rates or reaction surface rates of crystals, critical suspension concentrations), (b) physico-chemical properties (bulk density, dimensions of generated crystals, ion diffusion coefficients in the solution), (c) operating parameters (macroscopic velocity, flow, or pressure gradient of the solution, ion concentration) (d) microfluidic data (geometry, flow area), (e) porosity data in Darcy description (initial porosity, specific surface area, tortuosity). During the modeling of flow and transport in three

  20. Neoclassical transport of energetic beam ions in the Large Helical Device

    International Nuclear Information System (INIS)

    Murakami, Sadayoshi; Yamada, Hiroshi; Kaneko, Osamu

    2000-01-01

    The neoclassical (collisional) transport of energetic ions is investigated by the global neoclassical transport simulation in the Large Helical Device (LHD). The steady state distributions of energetic ions are evaluated assuming an energetic particle source by NBI heating (tangentally injected). Significant radial transport of energetic ions can be seen due to the radial motion of trapped particles in the velocity region below near critical velocity. Our simulation results show relatively good agreements with the experimental results of fast particle measurements in the LHD. This suggests an important role of neoclassical transport in the radial transport process of energetic ions in heliotrons. (author)

  1. Electron transport effects in ion induced electron emission

    Energy Technology Data Exchange (ETDEWEB)

    Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: adubus@ulb.ac.be; Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

    2007-03-15

    Ion induced electron emission (IIEE) is usually described as a three-step process, i.e. electron excitation by the incident projectile, electron transport (and multiplication) and electron escape through the potential barrier at the surface. In many cases, the first step of the process has been carefully described. The second step of the process, i.e. electron transport and multiplication, has often been treated in a very rough way, a simple decreasing exponential law being sometimes used. It is precisely the aim of the present work to show the importance of a correct description of electron transport and multiplication in a theoretical calculation of IIEE. A short overview of the electron transport models developed for IIEE is given in this work. The so-called 'Infinite medium slowing-down model' often used in recent works is evaluated by means of Monte Carlo simulations. In particular, the importance of considering correctly the semi-infinite character of the medium and the boundary condition at the vacuum-medium interface is discussed. Quantities like the electron escape depth are also briefly discussed. This evaluation has been performed in the particular case of protons (25keV

  2. Ion desorption phenomena induced by various types of multiply charged projectiles and by photons on solid surfaces

    International Nuclear Information System (INIS)

    Beyec, Y. Le.

    1991-01-01

    Ion desorption experiments are described in two regions of primary ion velocities corresponding to two distinct classes of interaction mechanism. At low speeds, atomic collisions take place, at higher speeds than the electron velocity, electronic collisions occur. Experiments with fast ions above 0.2 MeV/u are described, using 32 S and 235 U ions obtained in a cyclotron and a linear accelerator. Emission of H + ions from solid surfaces is measured and analyzed, and applied to the determination of the charge state of a fast ion in a solid. Experiments using single atomic and polyatomic, keV ions, and organic and CsI cluster ions as projectiles are also presented. Finally, laser desorption is discussed. (R.P.) 81 refs., 27 figs., 2 tabs

  3. High-order Two-Fluid Plasma Solver for Direct Numerical Simulations of Magnetic Flows with Realistic Transport Phenomena

    Science.gov (United States)

    Li, Zhaorui; Livescu, Daniel

    2017-11-01

    The two-fluid plasma equations with full transport terms, including temperature and magnetic field dependent ion and electron viscous stresses and heat fluxes, frictional drag force, and ohmic heating term have been solved by using the sixth-order non-dissipative compact scheme for plasma flows in several different regimes. In order to be able to fully resolve all the dynamically relevant time and length scales while maintaining computational feasibility, the assumptions of infinite speed of light and negligible electron inertia have been made. The accuracy and robustness of this two-fluid plasma solver in handling plasma flows have been tested against a series of canonical problems, such as Alfven-Whistler dispersion relation, electromagnetic plasma shock, magnetic reconnection, etc. For all test cases, grid convergence tests have been conducted to achieve fully resolved results. The roles of heat flux, viscosity, resistivity, Hall and Biermann battery effects, are investigated for the canonical flows studied.

  4. A Comparison of Numerical Strategies for Modeling the Transport Phenomena in High-Energy Laser Surface Alloying Process

    Directory of Open Access Journals (Sweden)

    Dipankar Chatterjee

    2017-06-01

    Full Text Available A comparative assessment is done on the effectiveness of some developed and reported macroscopic and mesoscopic models deployed for addressing the three-dimensional thermo-fluidic transport during high-power laser surface alloying process. The macroscopic models include the most celebrated k–ε turbulence model and the large eddy simulation (LES model, whereas a kinetic theory-based lattice Boltzmann (LB approach is invoked under the mesoscopic paradigm. The time-dependent Navier–Stokes equations are transformed into the k–ε turbulence model by performing the Reynolds averaging technique, whereas a spatial filtering operation is used to produce the LES model. The models are suitably modified to address the turbulent melt-pool convection by using a modified eddy viscosity expression including a damping factor in the form of square root of the liquid fraction. The LB scheme utilizes three separate distribution functions to monitor the underlying hydrodynamic, thermal and compositional fields. Accordingly, the kinematic viscosity, thermal and mass diffusivities are adjusted independently. A single domain fixed-grid enthalpy-porosity approach is utilized to model the phase change phenomena in conjunction with an appropriate enthalpy updating closure scheme. The performance of these models is recorded by capturing the characteristic nature of the thermo-fluidic transport during the laser material processing. The maximum values of the pertinent parameters in the computational domain obtained from several modeling efforts are compared to assess their capabilities. The comparison shows that the prediction from the k–ε turbulence model is higher than the LES and LB models. In addition, the results from all three models are compared with the available experimental results in the form of dimensionless composition of the alloyed layer along the dimensionless depth of the pool. The comparison reveals that the LB and the LES approaches are better

  5. Ion and impurity transport in turbulent, anisotropic magnetic fields

    International Nuclear Information System (INIS)

    Negrea, M; Petrisor, I; Isliker, H; Vogiannou, A; Vlahos, L; Weyssow, B

    2011-01-01

    We investigate ion and impurity transport in turbulent, possibly anisotropic, magnetic fields. The turbulent magnetic field is modeled as a correlated stochastic field, with Gaussian distribution function and prescribed spatial auto-correlation function, superimposed onto a strong background field. The (running) diffusion coefficients of ions are determined in the three-dimensional environment, using two alternative methods, the semi-analytical decorrelation trajectory (DCT) method, and test-particle simulations. In a first step, the results of the test-particle simulations are compared with and used to validate the results obtained from the DCT method. For this purpose, a drift approximation was made in slab geometry, and relatively good qualitative agreement between the DCT method and the test-particle simulations was found. In a second step, the ion species He, Be, Ne and W, all assumed to be fully ionized, are considered under ITER-like conditions, and the scaling of their diffusivities is determined with respect to varying levels of turbulence (varying Kubo number), varying degrees of anisotropy of the turbulent structures and atomic number. In a third step, the test-particle simulations are repeated without drift approximation, directly using the Lorentz force, first in slab geometry, in order to assess the finite Larmor radius effects, and second in toroidal geometry, to account for the geometric effects. It is found that both effects are important, most prominently the effects due to toroidal geometry and the diffusivities are overestimated in slab geometry by an order of magnitude.

  6. Ion and impurity transport in turbulent, anisotropic magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Negrea, M; Petrisor, I [Department of Physics, Association Euratom-MEdC, Romania, University of Craiova, A.I. Cuza str. 13, Craiova (Romania); Isliker, H; Vogiannou, A; Vlahos, L [Section of Astrophysics, Astronomy and Mechanics, Department of Physics, University of Thessaloniki, Association Euratom-Hellenic Republic, 541 24 Thessaloniki (Greece); Weyssow, B [Physique Statistique-Plasmas, Association Euratom-Etat Belge, Universite Libre de Bruxelles, Campus Plaine, Bd. du Triomphe, 1050 Bruxelles (Belgium)

    2011-08-15

    We investigate ion and impurity transport in turbulent, possibly anisotropic, magnetic fields. The turbulent magnetic field is modeled as a correlated stochastic field, with Gaussian distribution function and prescribed spatial auto-correlation function, superimposed onto a strong background field. The (running) diffusion coefficients of ions are determined in the three-dimensional environment, using two alternative methods, the semi-analytical decorrelation trajectory (DCT) method, and test-particle simulations. In a first step, the results of the test-particle simulations are compared with and used to validate the results obtained from the DCT method. For this purpose, a drift approximation was made in slab geometry, and relatively good qualitative agreement between the DCT method and the test-particle simulations was found. In a second step, the ion species He, Be, Ne and W, all assumed to be fully ionized, are considered under ITER-like conditions, and the scaling of their diffusivities is determined with respect to varying levels of turbulence (varying Kubo number), varying degrees of anisotropy of the turbulent structures and atomic number. In a third step, the test-particle simulations are repeated without drift approximation, directly using the Lorentz force, first in slab geometry, in order to assess the finite Larmor radius effects, and second in toroidal geometry, to account for the geometric effects. It is found that both effects are important, most prominently the effects due to toroidal geometry and the diffusivities are overestimated in slab geometry by an order of magnitude.

  7. Ion and impurity transport in turbulent, anisotropic magnetic fields

    Science.gov (United States)

    Negrea, M.; Petrisor, I.; Isliker, H.; Vogiannou, A.; Vlahos, L.; Weyssow, B.

    2011-08-01

    We investigate ion and impurity transport in turbulent, possibly anisotropic, magnetic fields. The turbulent magnetic field is modeled as a correlated stochastic field, with Gaussian distribution function and prescribed spatial auto-correlation function, superimposed onto a strong background field. The (running) diffusion coefficients of ions are determined in the three-dimensional environment, using two alternative methods, the semi-analytical decorrelation trajectory (DCT) method, and test-particle simulations. In a first step, the results of the test-particle simulations are compared with and used to validate the results obtained from the DCT method. For this purpose, a drift approximation was made in slab geometry, and relatively good qualitative agreement between the DCT method and the test-particle simulations was found. In a second step, the ion species He, Be, Ne and W, all assumed to be fully ionized, are considered under ITER-like conditions, and the scaling of their diffusivities is determined with respect to varying levels of turbulence (varying Kubo number), varying degrees of anisotropy of the turbulent structures and atomic number. In a third step, the test-particle simulations are repeated without drift approximation, directly using the Lorentz force, first in slab geometry, in order to assess the finite Larmor radius effects, and second in toroidal geometry, to account for the geometric effects. It is found that both effects are important, most prominently the effects due to toroidal geometry and the diffusivities are overestimated in slab geometry by an order of magnitude.

  8. Cross Sections and Transport Properties of BR- Ions in AR

    Science.gov (United States)

    Jovanovic, Jasmina; Stojanovic, Vladimir; Raspopovic, Zoran; Petrovic, Zoran

    2014-10-01

    We have used a combination of a simple semi-analytic theory - Momentum Transfer Theory (MTT) and exact Monte Carlo (MC) simulations to develop Br- in Ar momentum transfer cross section based on the available data for reduced mobility at the temperature T = 300 K over the range 10 Td higher energies based on behavior of similar ions in similar gases and by the addition of the total detachment cross section that was used from the threshold around 7.7 eV. Relatively complete set was derived which can be used in modeling of plasmas by both hybrid, particle in cell (PIC) and fluid codes. A good agreement between calculated and measured ion mobilities and longitudinal diffusion coefficients is an independent proof of the validity of the cross sections that were derived for the negative ion mobility data. In addition to transport coefficients we have also calculated the net rate coefficients of elastic scattering and detachment. Author acknowledge Ministry of Education, Science and Technology, Proj. Nos. 171037 and 410011.

  9. Thermochemical conversion of biomass in smouldering combustion across scales: The roles of heterogeneous kinetics, oxygen and transport phenomena.

    Science.gov (United States)

    Huang, Xinyan; Rein, Guillermo

    2016-05-01

    The thermochemical conversion of biomass in smouldering combustion is investigated here by combining experiments and modeling at two scales: matter (1mg) and bench (100g) scales. Emphasis is put on the effect of oxygen (0-33vol.%) and oxidation reactions because these are poorly studied in the literature in comparison to pyrolysis. The results are obtained for peat as a representative biomass for which there is high-quality experimental data published previously. Three kinetic schemes are explored, including various steps of drying, pyrolysis and oxidation. The kinetic parameters are found using the Kissinger-Genetic Algorithm method, and then implemented in a one-dimensional model of heat and mass transfer. The predictions are validated with thermogravimetric and bench-scale experiments and then analyzed to unravel the role of heterogeneous reaction. This is the first time that the influence of oxygen on biomass smouldering is explained in terms of both chemistry and transport phenomena across scales. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. Investigation of the Mesoporous Metal-Organic Framework as a New Platform To Study the Transport Phenomena of Biomolecules.

    Science.gov (United States)

    Chen, Yao; Hong, Seongmin; Fu, Chung-Wei; Hoang, Tran; Li, Xiao; Valencia, Veronica; Zhang, Zhenjie; Perman, Jason A; Ma, Shengqian

    2017-03-29

    Mesoporous materials, Tb-mesoMOF and MCM-41, were used to study the transport phenomena of biomolecules entering the interior pores from solution. Vitamins B 12 and B 2 were successfully encapsulated into these mesoporous materials, whereas Tb-mesoMOF (0.33 g of B 12 /g, 0.01 g of B 2 /g) adsorbed a higher amount of vitamin per mass than MCM-41 (0.21 g of B 12 /g, 0.002 g of B 2 /g). The diffusion mechanism of the biomolecules entering Tb-mesoMOF was evaluated using a mathematical model. The Raman spectroscopy studies showed vitamin B 12 has been encapsulated within Tb-mesoMOF's pores, and evaluation of the peak shifts indicated strong interactions linking vitamin B 12 's pyrroline moiety with Tb-mesoMOF's triazine and benzoate rings. Because of these stronger interactions between the vitamins and Tb-mesoMOF, longer egress times were observed than with MCM-41.

  11. Neoclassical transport of energetic minority tail ions generated by ion-cyclotron resonance heating in tokamak geometry

    International Nuclear Information System (INIS)

    Chang, C.S.; Hammett, G.W.; Goldston, R.J.

    1990-01-01

    Neoclassical transport of energetic minority tail ions, which are generated by high powered electromagnetic waves of the Ion Cyclotron Range of Frequencies (ICRF) at the fundamental harmonic resonance, is studied analytically in tokamak geometry. The effect of Coulomb collisions on the tail ion transport is investigated in the present work. The total tail ion transport will be the sum of the present collision-driven transport and the wave-driven transport, which is due to the ICRF-wave scattering of the tail particles as reported in the literature. The transport coefficients have been calculated kinetically, and it is found that the large tail ion viscosity, driven by the localized ICRF-heating and Coulomb slowing-down collisions, induces purely convective particle transport of the tail species, while the energy transport is both convective and diffusive. The rate of radial particle transport is shown to be usually small, but the rate of radial energy transport is larger and may not be negligible compared to the Coulomb slowing-down rate. 18 refs., 2 figs

  12. Hall-Effect Thruster Simulations with 2-D Electron Transport and Hydrodynamic Ions

    Science.gov (United States)

    Mikellides, Ioannis G.; Katz, Ira; Hofer, Richard H.; Goebel, Dan M.

    2009-01-01

    A computational approach that has been used extensively in the last two decades for Hall thruster simulations is to solve a diffusion equation and energy conservation law for the electrons in a direction that is perpendicular to the magnetic field, and use discrete-particle methods for the heavy species. This "hybrid" approach has allowed for the capture of bulk plasma phenomena inside these thrusters within reasonable computational times. Regions of the thruster with complex magnetic field arrangements (such as those near eroded walls and magnets) and/or reduced Hall parameter (such as those near the anode and the cathode plume) challenge the validity of the quasi-one-dimensional assumption for the electrons. This paper reports on the development of a computer code that solves numerically the 2-D axisymmetric vector form of Ohm's law, with no assumptions regarding the rate of electron transport in the parallel and perpendicular directions. The numerical challenges related to the large disparity of the transport coefficients in the two directions are met by solving the equations in a computational mesh that is aligned with the magnetic field. The fully-2D approach allows for a large physical domain that extends more than five times the thruster channel length in the axial direction, and encompasses the cathode boundary. Ions are treated as an isothermal, cold (relative to the electrons) fluid, accounting for charge-exchange and multiple-ionization collisions in the momentum equations. A first series of simulations of two Hall thrusters, namely the BPT-4000 and a 6-kW laboratory thruster, quantifies the significance of ion diffusion in the anode region and the importance of the extended physical domain on studies related to the impact of the transport coefficients on the electron flow field.

  13. Experimental study of high current negative ion sources D- / H-. Analysis based on the simulation of the negative ion transport in the plasma source

    International Nuclear Information System (INIS)

    Riz, D.

    1996-01-01

    In the frame of the development of a neutral beam injection system able to work the ITER tokamak (International Thermonuclear Experimental Reactor), two negative ion sources, Dragon and Kamaboko, have been installed on the MANTIS test bed in Cadarache, and studies in order to extract 20 mA/cm 2 of D - . The two production modes of negative ions have been investigated: volume production; surface production after cesium injection in the discharge. Experiments have shown that cesium seeding is necessary in order to reach the requested performances for ITER. 20 mA/cm 2 have been extracted from the Kamaboko source for an arc power density of 2.5 kW/liter. Simultaneously, a code called NIETZSCHE has been developed to simulate the negative ions transport in the source plasma, from their birth place to the extraction holes. The ion trajectory is calculated by numerically solving the 3D motion equation, while the atomic processes of destruction, of elastic collisions H - /H + and of charge exchange H - /H 0 are handled at each time step by a Monte Carlo procedure. The code allows to obtain the extraction probability of a negative ion produced at a given location. The calculations performed with NIETZSCHE have allowed to explain several phenomena observed on negative ion sources, such as the isotopic effect H - /D - and the influence of the polarisation of the plasma grid and of the magnetic filter on the negative ions current. The code has also shown that, in the type of sources contemplated for ITER, working with large arc power densities (> 1 kW/liter), only negative ions produced in volume at a distance lower that 2 cm from the plasma grid and those produced at the grid surface have a chance of being extracted. (author)

  14. Activation of ion transport systems during cell volume regulation

    International Nuclear Information System (INIS)

    Eveloff, J.L.; Warnock, D.G.

    1987-01-01

    This review discusses the activation of transport pathways during volume regulation, including their characteristics, the possible biochemical pathways that may mediate the activation of transport pathways, and the relations between volume regulation and transepithelial transport in renal cells. Many cells regulate their volume when exposed to an anisotonic medium. The changes in cell volume are caused by activation of ion transport pathways, plus the accompanying osmotically driven water movement such that cell volume returns toward normal levels. The swelling of hypertonically shrunken cells is termed regulatory volume increase (RVI) and involves an influx of NaCl into the cell via either activation of Na-Cl, Na-K-2Cl cotransport systems, or Na + -H + and Cl - -HCO 3 - exchangers. The reshrinking of hypotonically swollen cells is termed regulatory volume decrease (RVD) and involves an efflux of KCl and water from the cell by activation of either separate K + and Cl - conductances, a K-Cl cotransport system, or parallel K + -H + and Cl - -HCO 3 - exchangers. The biochemical mechanisms involved in the activation of transport systems are largely unknown, however, the phosphoinositide pathway may be implicated in RVI; phorbol esters, cGMP, and Ca 2+ affect the process of volume regulation. Renal tubular cells, as well as the blood cells that transverse the medulla, are subjected to increasing osmotic gradients from the corticomedullary junction to the papillary tip, as well as changing interstitial and tubule fluid osmolarity, depending on the diuretic state of the animal. Medullary cells from the loop of Henle and the papilla can volume regulate by activating Na-K-2Cl cotransport or Na + -H + and Cl - -HCO 3 - exchange systems

  15. Electron density measurements during ion beam transport on Gamble II

    International Nuclear Information System (INIS)

    Weber, B.V.; Hinshelwood, D.D.; Neri, J.M.; Ottinger, P.F.; Rose, D.V.; Stephanakis, S.J.; Young, F.C.

    1999-01-01

    High-sensitivity laser interferometry was used to measure the electron density created when an intense proton beam (100 kA, 1 MeV, 50 ns) from the Gamble II generator was transported through low-pressure gas as part of a project investigating Self-Pinched Transport (SPT) of intense ion beams. This measurement is non-perturbing and sufficiently quantitative to allow benchmarking of codes (particularly IPROP) used to model beam-gas interaction and ion-beam transport. Very high phase sensitivity is required for this measurement. For example, a 100-kA, 1-MeV, 10-cm-radius proton beam with uniform current density has a line-integrated proton density equal to n b L = 3 x 10 13 cm -2 . An equal electron line-density, n e L = n b L, (expected for transport in vacuum) will be detected as a phase shift of the 1.064 microm laser beam of only 0.05degree, or an optical path change of 1.4 x 10 -4 waves (about the size of a hydrogen atom). The time-history of the line-integrated electron density, measured across a diameter of the transport chamber at 43 cm from the input aperture, starts with the proton arrival time and decays differently depending on the gas pressure. The gas conditions included vacuum (10 -4 Torr air), 30 to 220 mTorr He, and 1 Torr air. The measured densities vary by three orders of magnitude, from 10 13 to 10 16 cm -2 for the range of gas pressures investigated. In vacuum, the measured electron densities indicate only co-moving electrons (n e L approximately n b L). In He, when the gas pressure is sufficient for ionization by beam particles and SPT is observed, n e L increases to about 10 n b L. At even higher pressures where electrons contribute to ionization, even higher electron densities are observed with an ionization fraction of about 2%. The diagnostic technique as used on the SPT experiment will be described and a summary of the results will be given. The measurements are in reasonable agreement with theoretical predictions from the IPROP code

  16. Transport of Zn(OH)4(-2) ions across a polyolefin microporous membrane

    Science.gov (United States)

    Krejci, Ivan; Vanysek, Peter; Trojanek, Antonin

    1993-04-01

    Transport of ZN(OH)4(2-) ions through modified microporous polypropylene membranes (Celgard 3401, 350140) was studied using polarography and conductometry. Soluble Nafion as an ion exchange modifying agent was applied to the membrane by several techniques. The influence of Nafion and a surfactant on transport of zinc ions through the membrane was studied. A relationship between membrane impedance and the rate of Zn(OH)4(2-) transport was found. The found correlation between conductivity, ion permeability and Nafion coverage suggests a suitable technique of membrane preparation to obtain desired zinc ion barrier properties.

  17. Fluid transport and ion fluxes in mammalian kidney proximal tubule: a model analysis of isotonic transport

    DEFF Research Database (Denmark)

    Larsen, E.H.; Møbjerg, N.; Sørensen, Jens Nørkær

    2006-01-01

    transport similar to rat proximal tubule. Na+ recirculation is required for truly isotonic transport. The tonicity of the absorbate and the recirculation flux depend critically on ion permeabilities of interspace basement membrane. Conclusion: Our model based on solute-solvent coupling in lateral space......Aim: By mathematical modelling, we analyse conditions for near-isotonic and isotonic transport by mammalian kidney proximal tubule. Methods: The model comprises compliant lateral intercellular space (lis) and cells, and infinitely large luminal and peritubular compartments with diffusible species......: Na+, K+, Cl and an intracellular non-diffusible anion. Unknown model variables are solute concentrations, electrical potentials, volumes and hydrostatic pressures in cell and lis, and transepithelial potential. We used data mainly from rat proximal tubule to model epithelial cells and interspace...

  18. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.Y.; Horton, W. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies); Coppi, B. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Research Lab. of Electronics)

    1992-01-01

    Experiments show that the observed radial profiles of the ion thermal conductivity {chi}{sub i} have the opposite shapes with those obtained from the ion temperature gradient mode ({eta}{sub i} mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal {eta}{sub i} mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal {eta}{sub i} mode, and that the observed reduction of {chi}{sub i}(r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the {chi}{sub i}. It is shown the new formula fits well the observed {chi}{sub i}(r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula.

  19. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.Y.; Horton, W. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Coppi, B. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Research Lab. of Electronics

    1992-08-01

    Experiments show that the observed radial profiles of the ion thermal conductivity {chi}{sub i} have the opposite shapes with those obtained from the ion temperature gradient mode ({eta}{sub i} mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal {eta}{sub i} mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal {eta}{sub i} mode, and that the observed reduction of {chi}{sub i}(r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the {chi}{sub i}. It is shown the new formula fits well the observed {chi}{sub i}(r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula.

  20. Anomalous ion thermal transport in hot ion plasmas by the ion temperature gradient mode

    International Nuclear Information System (INIS)

    Kim, J.Y.; Horton, W.; Coppi, B.

    1992-01-01

    Experiments show that the observed radial profiles of the ion thermal conductivity χ i have the opposite shapes with those obtained from the ion temperature gradient mode (η i mode) turbulence model by the traditional mixing length estimate. In this work, this radial profile problem is reconsidered with an electromagnetic study of the linear stability of the toroidal η i mode and a new rule for choosing the mixing length. It is first shown that the electromagnetic effect gives a significant stabilizing effect on the toroidal η i mode, and that the observed reduction of χ i (r) in the core region can be explained by this electromagnetic effect. Secondly, in view of earlier numerical simulations showing the transfer of fluctuation energy to larger scales that those for the fastest growth rate, as well as fluctuation measurements indicating longer radial correlation lengths, a new mixing length formula is proposed to explain the radial increase of the χ i . It is shown the new formula fits well the observed χ i (r) profiles in two TFTR supershot discharges and also gives the scaling law in the current and the magnetic field which agrees better with experiment than the conventional formula

  1. Investigations of Atomic Transport Induced by Heavy Ion Irradiation

    Science.gov (United States)

    Banwell, Thomas Clyde

    The mechanisms of atomic transport induced by ion irradiation generally fall into the categories of anisotropic or isotropic processes. Typical examples of these are recoil implantation and cascade mixing, respectively. We have measured the interaction of these processes in the mixing of Ti/SiO(,2)/Si, Cr/SiO(,2)/Si and Ni/SiO(,2)/Si multi-layers irradiated with Xe at fluences of 0.01 - 10 x 10('15)cm('-2). The fluence dependence of net metal transport into the underlying layers was measured with different thicknesses of SiO(,2) and different sample temperatures during irradiation (-196 to 500C). There is a linear dependence at low fluences. At high fluences, a square-root behavior predominates. For thin SiO(,2) layers (primary recoils is quite pronounced since the gross mixing is small. A significant correlation exists between the mixing and the energy deposited through elastic collisions F(,D ). Several models are examined in an attempt to describe the transport process in Ni/SiO(,2). It is likely that injection of Ni by secondary recoil implantation is primarily responsible for getting Ni into the SiO(,2). Secondary recoil injection is thought to scale with F(,D). Trends in the mixing rates indicate that the dominant mechanism for Ti and Cr could be the same as for Ni. The processes of atomic transport and phase formation clearly fail to be separable at higher temperatures. A positive correlation with chemical reactivity emerges at higher irradiation temperatures. The temperature at which rapid mixing occurs is not much below that for spontaneous thermal reaction. Less Ni is retained in the SiO(,2) at high irradiation temperatures. Ni incorporated in the SiO(,2) by low temperature irradiation is not expelled during a consecutive high temperature irradiation. The Ni remains trapped within larger clusters during a sequential 500C irradiation. (Abstract shortened with permission of author.).

  2. Solenoidal Fields for Ion Beam Transport and Focusing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Edward P.; Leitner, Matthaeus

    2007-11-01

    In this report we calculate time-independent fields of solenoidal magnets that are suitable for ion beam transport and focusing. There are many excellent Electricity and Magnetism textbooks that present the formalism for magnetic field calculations and apply it to simple geometries [1-1], but they do not include enough relevant detail to be used for designing a charged particle transport system. This requires accurate estimates of fringe field aberrations, misaligned and tilted fields, peak fields in wire coils and iron, external fields, and more. Specialized books on magnet design, technology, and numerical computations [1-2] provide such information, and some of that is presented here. The AIP Conference Proceedings of the US Particle Accelerator Schools [1-3] contain extensive discussions of design and technology of magnets for ion beams - except for solenoids. This lack may be due to the fact that solenoids have been used primarily to transport and focus particles of relatively low momenta, e.g. electrons of less than 50 MeV and protons or H- of less than 1.0 MeV, although this situation may be changing with the commercial availability of superconducting solenoids with up to 20T bore field [1-4]. Internal reports from federal laboratories and industry treat solenoid design in detail for specific applications. The present report is intended to be a resource for the design of ion beam drivers for Inertial Fusion Energy [1-5] and Warm Dense Matter experiments [1-6], although it should also be useful for a broader range of applications. The field produced by specified currents and material magnetization can always be evaluated by solving Maxwell's equations numerically, but it is also desirable to have reasonably accurate, simple formulas for conceptual system design and fast-running beam dynamics codes, as well as for general understanding. Most of this report is devoted to such formulas, but an introduction to the Tosca{copyright} code [1-7] and some

  3. Solenoidal Fields for Ion Beam Transport and Focusing

    International Nuclear Information System (INIS)

    Lee, Edward P.; Leitner, Matthaeus

    2007-01-01

    In this report we calculate time-independent fields of solenoidal magnets that are suitable for ion beam transport and focusing. There are many excellent Electricity and Magnetism textbooks that present the formalism for magnetic field calculations and apply it to simple geometries (1-1), but they do not include enough relevant detail to be used for designing a charged particle transport system. This requires accurate estimates of fringe field aberrations, misaligned and tilted fields, peak fields in wire coils and iron, external fields, and more. Specialized books on magnet design, technology, and numerical computations (1-2) provide such information, and some of that is presented here. The AIP Conference Proceedings of the US Particle Accelerator Schools (1-3) contain extensive discussions of design and technology of magnets for ion beams - except for solenoids. This lack may be due to the fact that solenoids have been used primarily to transport and focus particles of relatively low momenta, e.g. electrons of less than 50 MeV and protons or H- of less than 1.0 MeV, although this situation may be changing with the commercial availability of superconducting solenoids with up to 20T bore field (1-4). Internal reports from federal laboratories and industry treat solenoid design in detail for specific applications. The present report is intended to be a resource for the design of ion beam drivers for Inertial Fusion Energy (1-5) and Warm Dense Matter experiments (1-6), although it should also be useful for a broader range of applications. The field produced by specified currents and material magnetization can always be evaluated by solving Maxwell's equations numerically, but it is also desirable to have reasonably accurate, simple formulas for conceptual system design and fast-running beam dynamics codes, as well as for general understanding. Most of this report is devoted to such formulas, but an introduction to the Tosca(copyright) code (1-7) and some numerical

  4. A Numerical Simulation of Transport Phenomena During the Horizontal Single Belt Casting Process Using an Inclined Feeding System

    Science.gov (United States)

    Xu, Mianguang; Isac, Mihaiela; Guthrie, Roderick I. L.

    2018-06-01

    Horizontal single belt casting (HSBC) has great potential to replace current conventional continuous casting (CCC) processes for sheet metal production, by directly casting 3 to 1 mm sheet for the automobile industry. In the present paper, two-dimensional mathematical models were developed to study transport phenomena, for the case of an inclined wall feeding system for a liquid aluminum wrought alloy (AA6111). Based on the commercial software ANSYS FLUENT 14.5 and user-defined functions, a two-layer turbulence model was used to examine the fluid flow emanating from a slot nozzle set above a water-cooled, high-speed, steel belt. The Volume of Fluid (VOF) method was used to predict the shape of the melt-air interface. A transformed coordinate system ( x', y') was established in order to analyze the fluid flow on the inclined wall of the feeding system. The total pressure gauge gradient ( ∂p total/ ∂x) was used to describe the behavior of the melt film inside the slot nozzle of the head box. The modeling results show that during the melt film falling process, the total gauge pressure varies within the slot nozzle, which can decrease the stability of the falling film. The first impingement between the falling film and the inclined refractory wall of the feeding system gives rise to a local oscillation, and this influences the stability of the melt film moving downwards. At the rear meniscus position between the inclined wall and the moving belt, there is a clear vibration of the air-melt interface, together with a recirculation zone. The weak vibration of the air-melt interface could be induced by the periodic variation of the melt-air interface. Moreover, the formation of tiny air pockets is predicted. Finally, on the inclined wall of the feeding system, a suitable length of the transition area is needed to avoid over-acceleration of the melt film due to the force of gravity.

  5. A Numerical Simulation of Transport Phenomena During the Horizontal Single Belt Casting Process Using an Inclined Feeding System

    Science.gov (United States)

    Xu, Mianguang; Isac, Mihaiela; Guthrie, Roderick I. L.

    2018-03-01

    Horizontal single belt casting (HSBC) has great potential to replace current conventional continuous casting (CCC) processes for sheet metal production, by directly casting 3 to 1 mm sheet for the automobile industry. In the present paper, two-dimensional mathematical models were developed to study transport phenomena, for the case of an inclined wall feeding system for a liquid aluminum wrought alloy (AA6111). Based on the commercial software ANSYS FLUENT 14.5 and user-defined functions, a two-layer turbulence model was used to examine the fluid flow emanating from a slot nozzle set above a water-cooled, high-speed, steel belt. The Volume of Fluid (VOF) method was used to predict the shape of the melt-air interface. A transformed coordinate system (x', y') was established in order to analyze the fluid flow on the inclined wall of the feeding system. The total pressure gauge gradient (∂p total/∂x) was used to describe the behavior of the melt film inside the slot nozzle of the head box. The modeling results show that during the melt film falling process, the total gauge pressure varies within the slot nozzle, which can decrease the stability of the falling film. The first impingement between the falling film and the inclined refractory wall of the feeding system gives rise to a local oscillation, and this influences the stability of the melt film moving downwards. At the rear meniscus position between the inclined wall and the moving belt, there is a clear vibration of the air-melt interface, together with a recirculation zone. The weak vibration of the air-melt interface could be induced by the periodic variation of the melt-air interface. Moreover, the formation of tiny air pockets is predicted. Finally, on the inclined wall of the feeding system, a suitable length of the transition area is needed to avoid over-acceleration of the melt film due to the force of gravity.

  6. Structure, Ion Transport, and Rheology of Nanoparticle Salts

    KAUST Repository

    Wen, Yu Ho

    2014-07-08

    Above a critical surface chemistry-dependent particle loading associated with nanoscale interparticle spacing, ligand-ligand interactions-both electrostatic and steric-come into play and govern the structure and dynamics of charged oligomer-functionalized nanoparticle suspensions. We report in particular on the structure, ion transport, and rheology of suspensions of nanoparticle salts created by cofunctionalization of silica particles with tethered sulfonate salts and oligomers. Dispersion of the hairy ionic particles into medium and high dielectric constant liquids yields electrolytes with unique structure and transport properties. We find that electrostatic repulsion imparted by ion dissociation can be tuned to control the dispersion state and rheology through counterion size (i.e., Li+, Na+, and K+) and dielectric properties of the dispersing medium. Analysis of small-angle X-ray scattering (SAXS) structure factors and the mechanical modulus shows that when the interparticle spacing approaches nanometer dimensions, weakly entangled anchored ligands experience strong and long-lived topological constraints analogous to those normally found in well-entangled polymeric fluids. This finding provides insight into the molecular origins of the surprisingly similar rubbery plateau moduli observed in hairy nanoparticle suspensions and entangled polymers of the same chemistry as the tethered ligands. Additionally, we find that a time-composition superposition (TCS) principle exists for the suspensions, which can be used to substantially extend the observation time over which dynamics are observed in jammed, soft glassy suspensions. Application of TCS reveals dynamical similarities between the suspensions and entangled solutions of linear polymer chains; i.e., a hairy particle trapped in a cage appears to exhibit analogous dynamics to a long polymer chain confined to a tube. © 2014 American Chemical Society.

  7. STM and transport measurements of highly charged ion modified materials

    International Nuclear Information System (INIS)

    Pomeroy, J.M.; Grube, H.; Perrella, A.C.; Gillaspy, J.D.

    2007-01-01

    Careful measurements of highly charged ions (HCIs) colliding with gases and surfaces have provided glimpses of intense electronic interactions, but a comprehensive model for the interaction mechanisms, time scales, and resultant nano-features that bridges materials systems is yet to be realized. At the National Institute of Standards and Technology (NIST) electron beam ion trap (EBIT) facility, new apparatus is now connected to the HCI beamline to allow preparation of clean, atomically flat surfaces of single crystals, e.g. gold, tungsten and silicon, and deposition and patterning of thin films, e.g. high resistivity oxides, ferromagnetic metals, normal metals and superconductors. Experiments reported here focus on the electronic and morphological structure of HCI induced nano-features. Current activities are focused on using in situ scanning tunneling microscope (STM) on Au(1 1 1) and (separately) ex situ transport measurements to study electronic properties within HCI modified magnetic multilayer systems. Specifically, we are fabricating magnetic multilayers similar to magnetic tunnel junctions (MTJs) (important in advanced magnetic field sensors and superconducting Josephson junction devices) and using HCIs to adjust critical electronic properties. The electrical response of the tunnel junction to HCIs provides a novel approach to performing HCI-induced nanostructure ensemble measurements

  8. Ion transport and phase transformation in thin film intercalation electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wunde, Fabian; Nowak, Susann; Muerter, Juliane; Hadjixenophontos, Efi; Berkemeier, Frank; Schmitz, Guido [Stuttgart Univ. (Germany). Inst. fuer Materialwissenschaft

    2017-11-15

    Thin film battery electrodes of the olivine structure LiFePO{sub 4} and the spinel phase LiMn{sub 2}O{sub 4} are deposited through ion-beam sputtering. The intercalation kinetics is studied by cyclo-voltammetry using variation of the cycling rate over 4 to 5 orders of magnitude. The well-defined layer geometry allows a detailed quantitative analysis. It is shown that LiFePO{sub 4} clearly undergoes phase separation during intercalation, although the material is nano-confined and very high charging rates are applied. We present a modified Randles-Sevcik evaluation adapted to phase-separating systems. Both the charging current and the overpotential depend on the film thickness in a systematic way. The analysis yields evidence that the grain boundaries are important short circuit paths for fast transport. They increase the electrochemical active area with increasing layer thickness. Evidence is obtained that the grain boundaries in LiFePO{sub 4} have the character of an ion-conductor of vanishing electronic conductivity.

  9. Paranormal phenomena

    Science.gov (United States)

    Gaina, Alex

    1996-08-01

    Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

  10. Transport and microstructural phenomena in bentonite clay with respect to the behavior and influence of Na, Cu, and U

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.; Muurinen, A.

    1989-12-01

    MX-80 Na smectite clay, essentially consisting of montmorillonite, was investigated with respect to major transport properties and rheological behavior. Duffison and percolation tests using sodium, copper, and uranium solutions were conducted both at room temperature and at 90deg C. The diffusion tests showed that Na migrates very rapidly by pore and surface diffusion. Cu appears to migrate at the same rate as many other cations, the major diffusion mechanism being surface diffusion. Cu tends to replace initially sorbed Na and exchangeable protons and charges the clay to yield 'Cu-bentonite' even on contacting the clay with rather dilute solutions (100 ppm Cu). Uranium was found to migrate approximately as Cu but precipitation of Na- or Ca U compounds forming a front zone appeared to be a rate-controlling mechanism. Thus, the diffusion profile had a very steep front, identified also by a SEM/EDX investigation. This indicates that the rate of advancement of the front is determined by the reaction rate. Although not being a true diffusion process, it can approximately be regarded as one, the coefficient of diffusion being 10-100 times lower than that of Cu. Behind the high concentration front, the clay becomes fully charged with U to form a 'U-bentonite' even at low concentration of the uranium solution (100 ppm U). The percolation and rheological investigations showed only moderate influence on the hydraulic conductivity and creep properties by an increased Na content (10000 ppm) or partial uptake by Cu or U. Considerable differences were found between samples investigated at room temperature and at 90deg C (effect of cementation). The microstructure was concluded to control a number of practically important physical properties. It determines the hydraulic conductivity and the rheological behaviour, and it has a very substantial influence on diffusive transport of ions in the porewater. (orig.)

  11. Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

    KAUST Repository

    Hong, Jongsup

    2012-07-01

    Ion transport membrane (ITM) based reactors have been suggested as a novel technology for several applications including fuel reforming and oxy-fuel combustion, which integrates air separation and fuel conversion while reducing complexity and the associated energy penalty. To utilize this technology more effectively, it is necessary to develop a better understanding of the fundamental processes of oxygen transport and fuel conversion in the immediate vicinity of the membrane. In this paper, a numerical model that spatially resolves the gas flow, transport and reactions is presented. The model incorporates detailed gas phase chemistry and transport. The model is used to express the oxygen permeation flux in terms of the oxygen concentrations at the membrane surface given data on the bulk concentration, which is necessary for cases when mass transfer limitations on the permeate side are important and for reactive flow modeling. The simulation results show the dependence of oxygen transport and fuel conversion on the geometry and flow parameters including the membrane temperature, feed and sweep gas flow, oxygen concentration in the feed and fuel concentration in the sweep gas. © 2012 Elsevier B.V.

  12. Hypoxia inhibits colonic ion transport via activation of AMP kinase.

    LENUS (Irish Health Repository)

    Collins, Danielle

    2012-02-01

    BACKGROUND AND AIMS: Mucosal hypoxia is a common endpoint for many pathological processes including ischemic colitis, colonic obstruction and anastomotic failure. Previous studies suggest that hypoxia modulates colonic mucosal function through inhibition of chloride secretion. However, the molecular mechanisms underlying this observation are poorly understood. AMP-activated protein kinase (AMPK) is a metabolic energy regulator found in a wide variety of cells and has been linked to cystic fibrosis transmembrane conductance regulator (CFTR) mediated chloride secretion in several different tissues. We hypothesized that AMPK mediates many of the acute effects of hypoxia on human and rat colonic electrolyte transport. METHODS: The fluorescent chloride indicator dye N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide was used to measure changes in intracellular chloride concentrations in isolated single rat colonic crypts. Ussing chamber experiments in human colonic mucosa were conducted to evaluate net epithelial ion transport. RESULTS: This study demonstrates that acute hypoxia inhibits electrogenic chloride secretion via AMPK mediated inhibition of CFTR. Pre-treatment of tissues with the AMPK inhibitor 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyyrazolo [1,5-a] pyrimidine (compound C) in part reversed the effects of acute hypoxia on chloride secretion. CONCLUSION: We therefore suggest that AMPK is a key component of the adaptive cellular response to mucosal hypoxia in the colon. Furthermore, AMPK may represent a potential therapeutic target in diseased states or in prevention of ischemic intestinal injury.

  13. Three-dimensional multi-phase flow computational fluid dynamics model for analysis of transport phenomena and thermal stresses in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Maher, A.R.; Al-Baghdadi, S. [International Technological Univ., London (United Kingdom). Dept. of Mechanical Engineering; Haroun, A.K.; Al-Janabi, S. [Babylon Univ., Babylon (Iraq). Dept. of Mechanical Engineering

    2007-07-01

    Fuel cell technology is expected to play an important role in meeting the growing demand for distributed generation because it can convert the chemical energy of a clean fuel directly into electrical energy. An operating fuel cell has varying local conditions of temperature, humidity, and power generation across the active area of the fuel cell in 3D. This paper presented a model that was developed to improve the basic understanding of the transport phenomena and thermal stresses in PEM fuel cells, and to investigate the behaviour of polymer membrane under hygro and thermal stresses during the cell operation. This comprehensive 3D, multiphase, non-isothermal model accounts for the major transport phenomena in a PEM fuel cell, notably convective and diffusive heat and mass transfer; electrode kinetics; transport and phase change mechanism of water; and potential fields. The model accounts for the liquid water flux inside the gas diffusion layers by viscous and capillary forces and can therefore predict the amount of liquid water inside the gas diffusion layers. This study also investigated the key parameters affecting fuel cell performance including geometry, materials and operating conditions. The model considers the many interacting, complex electrochemical, transport phenomena, thermal stresses and deformation that cannot be studied experimentally. It was concluded that the model can provide a computer-aided tool for the design and optimization of future fuel cells with much higher power density and lower cost. 21 refs., 2 tabs., 14 figs.

  14. Colloids: a review of current knowledge with a view to application to phenomena of transportation within PWR; Colloides: point de vue sur les connaissances actuelles en vue d`une application aux phenomenes de transport dans les REP

    Energy Technology Data Exchange (ETDEWEB)

    Guinard, L.

    1996-12-31

    In an attempt to minimise dosimetry within the primary circuit of PWR units, research is being carried out into understanding the phenomena of transportation and deposition of corrosion products. It is therefore desirable to known the form of these corrosion products and the laws governing this form. It is generally considered that they are in soluble or particulate form. A third starts with a general presentation of colloids and goes on to define points which are useful, both on a theoretical and experimental level, in terms of application to phenomena of transportation within PWRs. (author). 69 refs., 30 figs., 6 tabs., 3 appends.

  15. Electrochemical-mechanical coupled modeling and parameterization of swelling and ionic transport in lithium-ion batteries

    Science.gov (United States)

    Sauerteig, Daniel; Hanselmann, Nina; Arzberger, Arno; Reinshagen, Holger; Ivanov, Svetlozar; Bund, Andreas

    2018-02-01

    The intercalation and aging induced volume changes of lithium-ion battery electrodes lead to significant mechanical pressure or volume changes on cell and module level. As the correlation between electrochemical and mechanical performance of lithium ion batteries at nano and macro scale requires a comprehensive and multidisciplinary approach, physical modeling accounting for chemical and mechanical phenomena during operation is very useful for the battery design. Since the introduced fully-coupled physical model requires proper parameterization, this work also focuses on identifying appropriate mathematical representation of compressibility as well as the ionic transport in the porous electrodes and the separator. The ionic transport is characterized by electrochemical impedance spectroscopy (EIS) using symmetric pouch cells comprising LiNi1/3Mn1/3Co1/3O2 (NMC) cathode, graphite anode and polyethylene separator. The EIS measurements are carried out at various mechanical loads. The observed decrease of the ionic conductivity reveals a significant transport limitation at high pressures. The experimentally obtained data are applied as input to the electrochemical-mechanical model of a prismatic 10 Ah cell. Our computational approach accounts intercalation induced electrode expansion, stress generation caused by mechanical boundaries, compression of the electrodes and the separator, outer expansion of the cell and finally the influence of the ionic transport within the electrolyte.

  16. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.; Bojinov, M.; Betova, I.; Maekelae, K.; Saario, T. [VTT Manufacturing Technology, Espoo (Finland)

    1999-01-01

    . In addition, the films are to a large extent influenced by the kinetic factors determining their growth rate and steady state thickness. Thus a thermodynamic consideration of the film is not sufficient to model and predict its growth and dissolution. Instead, kinetic models based on in situ experimental data are required. The kinetic models presented in the literature for both ambient and high-temperature aqueous oxidation of metals lack a correlation between the structure of the oxide films and their electronic and ionic properties. Also, a quantitative treatment and thus the capability to predict material behaviour in varying conditions is lacking. A comprehensive understanding of the correlation between applied water chemistry, the behaviour of oxide films and optimum performance of the plant is thus also lacking. The situation calls for more experimental work combined with comprehensive modelling of the behaviour of both the compact and the porous part of the oxide film formed on a metal surface. This will make it possible to recognise the rate-limiting steps of the processes in the film, and thus to influence the rate of activity incorporation and different corrosion phenomena related to transport of species in the film. (author) 210 refs.

  17. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    International Nuclear Information System (INIS)

    Laitinen, T.; Bojinov, M.; Betova, I.; Maekelae, K.; Saario, T.

    1999-01-01

    . In addition, the films are to a large extent influenced by the kinetic factors determining their growth rate and steady state thickness. Thus a thermodynamic consideration of the film is not sufficient to model and predict its growth and dissolution. Instead, kinetic models based on in situ experimental data are required. The kinetic models presented in the literature for both ambient and high-temperature aqueous oxidation of metals lack a correlation between the structure of the oxide films and their electronic and ionic properties. Also, a quantitative treatment and thus the capability to predict material behaviour in varying conditions is lacking. A comprehensive understanding of the correlation between applied water chemistry, the behaviour of oxide films and optimum performance of the plant is thus also lacking. The situation calls for more experimental work combined with comprehensive modelling of the behaviour of both the compact and the porous part of the oxide film formed on a metal surface. This will make it possible to recognise the rate-limiting steps of the processes in the film, and thus to influence the rate of activity incorporation and different corrosion phenomena related to transport of species in the film. (author)

  18. The Properties Of And Transport Phenomena In Oxide Films On Iron, Nickel, Chromium And Their Alloys In Aqueous Environments

    International Nuclear Information System (INIS)

    Saario, T.; Laitinen, T.; Maekelae, K.; Bojinov, M.; Betova, I.

    1998-07-01

    . In addition, the films are to a large extent influenced by the kinetic factors determining their growth rate and steady state thickness. Thus a thermodynamic consideration of the film is not sufficient to model and predict its growth and dissolution. Instead, kinetic models based on in situ experimental data are required. The kinetic models presented in the literature for both ambient and high-temperature aqueous oxidation of metals lack a correlation between the structure of the oxide films and their electronic and ionic properties. Also, a quantitative treatment and thus the capability to predict material behaviour in varying conditions is lacking. A comprehensive understanding of the correlation between applied water chemistry, the behaviour of oxide films and optimum performance of the plant is thus also lacking. The situation calls for more experimental work combined with comprehensive modelling of the behaviour of both the dense and the porous part of the oxide film formed on a metal surface. This will make it possible to recognise the rate-limiting steps of the processes in the film, and thus to influence the rate of activity incorporation and different corrosion phenomena related to transport of species in the film. (author)

  19. Salinity tolerance in plants. Quantitative approach to ion transport starting from halophytes and stepping to genetic and protein engineering for manipulating ion fluxes.

    Science.gov (United States)

    Volkov, Vadim

    2015-01-01

    Ion transport is the fundamental factor determining salinity tolerance in plants. The Review starts from differences in ion transport between salt tolerant halophytes and salt-sensitive plants with an emphasis on transport of potassium and sodium via plasma membranes. The comparison provides introductory information for increasing salinity tolerance. Effects of salt stress on ion transport properties of membranes show huge opportunities for manipulating ion fluxes. Further steps require knowledge about mechanisms of ion transport and individual genes of ion transport proteins. Initially, the Review describes methods to measure ion fluxes, the independent set of techniques ensures robust and reliable basement for quantitative approach. The Review briefly summarizes current data concerning Na(+) and K(+) concentrations in cells, refers to primary thermodynamics of ion transport and gives special attention to individual ion channels and transporters. Simplified scheme of a plant cell with known transport systems at the plasma membrane and tonoplast helps to imagine the complexity of ion transport and allows choosing specific transporters for modulating ion transport. The complexity is enhanced by the influence of cell size and cell wall on ion transport. Special attention is given to ion transporters and to potassium and sodium transport by HKT, HAK, NHX, and SOS1 proteins. Comparison between non-selective cation channels and ion transporters reveals potential importance of ion transporters and the balance between the two pathways of ion transport. Further on the Review describes in detail several successful attempts to overexpress or knockout ion transporters for changing salinity tolerance. Future perspectives are questioned with more attention given to promising candidate ion channels and transporters for altered expression. Potential direction of increasing salinity tolerance by modifying ion channels and transporters using single point mutations is discussed and

  20. Salinity tolerance in plants. Quantitative approach to ion transport starting from halophytes and stepping to genetic and protein engineering for manipulating ion fluxes

    Directory of Open Access Journals (Sweden)

    Vadim eVolkov

    2015-10-01

    Full Text Available Ion transport is the fundamental factor determining salinity tolerance in plants. The Review starts from differences in ion transport between salt tolerant halophytes and salt-sensitive plants with an emphasis on transport of potassium and sodium via plasma membranes. The comparison provides introductory information for increasing salinity tolerance. Effects of salt stress on ion transport properties of membranes show huge opportunities for manipulating ion fluxes. Further steps require knowledge about mechanisms of ion transport and individual genes of ion transport proteins. Initially, the Review describes methods to measure ion fluxes, the independent set of techniques ensures robust and reliable basement for quantitative approach. The Review briefly summarises current data concerning Na+ and K+ concentrations in cells, refers to primary thermodynamics of ion transport and gives special attention to individual ion channels and transporters. Simplified scheme of a plant cell with known transport systems at the plasma membrane and tonoplast helps to imagine the complexity of ion transport and allows to choose specific transporters for modulating ion transport. The complexity is enhanced by the influence of cell size and cell wall on ion transport. Special attention is given to ion transporters and to potassium and sodium transport by HKT, HAK, NHX and SOS1 proteins. Comparison between nonselective cation channels and ion transporters reveals potential importance of ion transporters and the balance between the two pathways of ion transport. Further on the Review describes in detail several successful attempts to overexpress or knockout ion transporters for changing salinity tolerance. Future perspectives are questioned with more attention given to promising candidate ion channels and transporters for altered expression. Potential direction of increasing salinity tolerance by modifying ion channels and transporters using single point mutations is

  1. A multiscale-compatible approach in modeling ionic transport in the electrolyte of (Lithium ion) batteries

    NARCIS (Netherlands)

    Salvadori, A.; Grazioli, D.; Geers, M.G.D.; Danilov, D.L.; Notten, P.H.L.

    2015-01-01

    A novel approach in modeling the ionic transport in the electrolyte of Li-ion batteries is here resented. Diffusion and migration processes govern the transport of ions in solution in the absence of onvection. In the porous electrode theory [1] it is common to model these processes via mass balance

  2. Multigroup Boltzmann-Fokker-Planck approach for ion transport in amorphous media

    Energy Technology Data Exchange (ETDEWEB)

    Keen, N.D.; Prinja, A.K.; Dunham, G.D. [New Mexico Univ., Albuquerque, NM (United States). Chemical and Nuclear Engineering Dept.

    2001-07-01

    We present a MGMC approach for the transport of arbitrary mass ions having energies up to a few MeV. Specifically, we consider interactions with target atoms through Coulomb mediated elastic nuclear and inelastic electronic collisions and restrict considerations to ion implantation and energy deposition of primary ions in amorphous media. (orig.)

  3. Lateral charge transport from heavy-ion tracks in integrated circuit chips

    Science.gov (United States)

    Zoutendyk, J. A.; Schwartz, H. R.; Nevill, L. R.

    1988-01-01

    A 256K DRAM has been used to study the lateral transport of charge (electron-hole pairs) induced by direct ionization from heavy-ion tracks in an IC. The qualitative charge transport has been simulated using a two-dimensional numerical code in cylindrical coordinates. The experimental bit-map data clearly show the manifestation of lateral charge transport in the creation of adjacent multiple-bit errors from a single heavy-ion track. The heavy-ion data further demonstrate the occurrence of multiple-bit errors from single ion tracks with sufficient stopping power. The qualitative numerical simulation results suggest that electric-field-funnel-aided (drift) collection accounts for single error generated by an ion passing through a charge-collecting junction, while multiple errors from a single ion track are due to lateral diffusion of ion-generated charge.

  4. Beam-transport study of an isocentric rotating ion gantry with minimum number of quadrupoles

    International Nuclear Information System (INIS)

    Pavlovic, Marius; Griesmayer, Erich; Seemann, Rolf

    2005-01-01

    A beam-transport study of an isocentric gantry for ion therapy is presented. The gantry is designed with the number of quadrupoles down to the theoretical minimum, which is the feature published for the first time in this paper. This feature has been achieved without compromising the ion-optical functions of the beam-transport system that is capable of handling non-symmetric beams (beams with different emittances in vertical and horizontal plane), pencil-beam scanning, double-achromatic optics and beam-size control. Ion-optical properties of the beam-transport system are described, discussed and illustrated by computer simulations performed by the TRANSPORT-code

  5. Modelling of near-field radionuclide transport phenomena in a KBS-3V type of repository for nuclear waste with Goldsim Code - and verification against previous methods

    International Nuclear Information System (INIS)

    Pulkkanen, V.-M.; Nordman, H.

    2010-03-01

    Traditional radionuclide transport models overestimate significantly some phenomena, or completely ignore them. This motivates the development of new more precise models. As a result, this work is a description of commissioning of a new KBS-3V near-field radionuclide transport model, which has been done with a commercial software called GoldSim. According to earlier models, GoldSim model uses rz coordinates, but the solubilities of radionuclides have been treated more precisely. To begin with, the physical phenomena concerning near-field transport have been introduced according to GoldSim way of thinking. Also, the computational methods of GoldSim have been introduced and compared to methods used earlier. The actual verification of GoldSim model has been carried out by comparing the GoldSim results from simple cases to the corresponding results obtained with REPCOM, a software developed by VTT and used in several safety assessments. The results agree well. Finally, a few complicated cases were studied. In these cases, the REPCOM's limitations in handling of some phenomena become evident. The differences in the results are caused especially by the extension of the solubility limit to the whole computational domain, and the element-wise treatment of the solubilities which was used instead of nuclide-wise treatment. This work has been carried out as a special assignment to the former laboratory of Advanced Energy Systems in Helsinki University of Technology. The work was done at VTT. (orig.)

  6. Facilitated ion transport in all-solid-state flexible supercapacitors.

    Science.gov (United States)

    Choi, Bong Gill; Hong, Jinkee; Hong, Won Hi; Hammond, Paula T; Park, HoSeok

    2011-09-27

    The realization of highly flexible and all-solid-state energy-storage devices strongly depends on both the electrical properties and mechanical integrity of the constitutive materials and the controlled assembly of electrode and solid electrolyte. Herein we report the preparation of all-solid-state flexible supercapacitors (SCs) through the easy assembly of functionalized reduced graphene oxide (f-RGO) thin films (as electrode) and solvent-cast Nafion electrolyte membranes (as electrolyte and separator). In particular, the f-RGO-based SCs (f-RGO-SCs) showed a 2-fold higher specific capacitance (118.5 F/g at 1 A/g) and rate capability (90% retention at 30 A/g) compared to those of all-solid-state graphene SCs (62.3 F/g at 1A/g and 48% retention at 30 A/g). As proven by the 4-fold faster relaxation of the f-RGO-SCs than that of the RGO-SCs and more capacitive behavior of the former at the low-frequency region, these results were attributed to the facilitated ionic transport at the electrical double layer by means of the interfacial engineering of RGO by Nafion. Moreover, the superiority of all-solid-state flexible f-RGO-SCs was demonstrated by the good performance durability under the 1000 cycles of charging and discharging due to the mechanical integrity as a consequence of the interconnected networking structures. Therefore, this research provides new insight into the rational design and fabrication of all-solid-state flexible energy-storage devices as well as the fundamental understanding of ion and charge transport at the interface. © 2011 American Chemical Society

  7. A synthetic ion transporter that disrupts autophagy and induces apoptosis by perturbing cellular chloride concentrations

    Science.gov (United States)

    Busschaert, Nathalie; Park, Seong-Hyun; Baek, Kyung-Hwa; Choi, Yoon Pyo; Park, Jinhong; Howe, Ethan N. W.; Hiscock, Jennifer R.; Karagiannidis, Louise E.; Marques, Igor; Félix, Vítor; Namkung, Wan; Sessler, Jonathan L.; Gale, Philip A.; Shin, Injae

    2017-07-01

    Perturbations in cellular chloride concentrations can affect cellular pH and autophagy and lead to the onset of apoptosis. With this in mind, synthetic ion transporters have been used to disturb cellular ion homeostasis and thereby induce cell death; however, it is not clear whether synthetic ion transporters can also be used to disrupt autophagy. Here, we show that squaramide-based ion transporters enhance the transport of chloride anions in liposomal models and promote sodium chloride influx into the cytosol. Liposomal and cellular transport activity of the squaramides is shown to correlate with cell death activity, which is attributed to caspase-dependent apoptosis. One ion transporter was also shown to cause additional changes in lysosomal pH, which leads to impairment of lysosomal enzyme activity and disruption of autophagic processes. This disruption is independent of the initiation of apoptosis by the ion transporter. This study provides the first experimental evidence that synthetic ion transporters can disrupt both autophagy and induce apoptosis.

  8. ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS

    Science.gov (United States)

    2017-06-30

    NUMBER (Include area code) 30 June 2017 Briefing Charts 26 May 2017 - 30 June 2017 ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS ...Robert Martin N/A ION ACOUSTIC TURBULENCE, ANOMALOUS TRANSPORT, AND SYSTEM DYNAMICS IN HALL EFFECT THRUSTERS Robert Martin1, Jonathan Tran2 1AIR FORCE...Approved for Public Release; Distribution is Unlimited. PA# 17394 1 / 13 OUTLINE 1 INTRODUCTION 2 TRANSPORT 3 DYNAMIC SYSTEM 4 SUMMARY AND CONCLUSION

  9. Nano and Mesoscale Ion and Water Transport in Perfluorosulfonic AcidMembranes

    Science.gov (United States)

    2017-10-01

    Nano- and Mesoscale Ion and Water Transport in Perfluorosulfonic-Acid Membranes A. R. Crothers a,b , C. J. Radke a,b , A. Z. Weber a a...Berkeley, CA 94720, USA Water and aqueous cations transport along multiple length scales in perfluorosulfonic-acid membranes. Molecular interactions...as a function of hydration. A resistor network upscales the nanoscale properties to predict effective membrane ion and water transport and their

  10. Experimental study of high current negative ion sources D{sup -} / H{sup -}. Analysis based on the simulation of the negative ion transport in the plasma source; Etude experimentale de sources a fort courant d`ions negatifs D{sup -} / H{sup -}. Analyse fondee sur la simulation du transport des ions dans le plasma de la source

    Energy Technology Data Exchange (ETDEWEB)

    Riz, D.

    1996-10-30

    In the frame of the development of a neutral beam injection system able to work the ITER tokamak (International Thermonuclear Experimental Reactor), two negative ion sources, Dragon and Kamaboko, have been installed on the MANTIS test bed in Cadarache, and studies in order to extract 20 mA/cm{sup 2} of D{sup -}. The two production modes of negative ions have been investigated: volume production; surface production after cesium injection in the discharge. Experiments have shown that cesium seeding is necessary in order to reach the requested performances for ITER. 20 mA/cm{sup 2} have been extracted from the Kamaboko source for an arc power density of 2.5 kW/liter. Simultaneously, a code called NIETZSCHE has been developed to simulate the negative ions transport in the source plasma, from their birth place to the extraction holes. The ion trajectory is calculated by numerically solving the 3D motion equation, while the atomic processes of destruction, of elastic collisions H{sup -}/H{sup +} and of charge exchange H{sup -}/H{sup 0} are handled at each time step by a Monte Carlo procedure. The code allows to obtain the extraction probability of a negative ion produced at a given location. The calculations performed with NIETZSCHE have allowed to explain several phenomena observed on negative ion sources, such as the isotopic effect H{sup -}/D{sup -} and the influence of the polarisation of the plasma grid and of the magnetic filter on the negative ions current. The code has also shown that, in the type of sources contemplated for ITER, working with large arc power densities (> 1 kW/liter), only negative ions produced in volume at a distance lower that 2 cm from the plasma grid and those produced at the grid surface have a chance of being extracted. (author). 122 refs.

  11. Ion transport analysis of a high beta-poloidal JT-60U discharge

    International Nuclear Information System (INIS)

    Horton, W.; Tajima, T.; Dong, J.-Q.; Kim, J.-Y.; Kishimoto, Y.

    1997-01-01

    The high beta-poloidal discharge number 17110 in JT-60U (JT-60 Team, IAEA, Vienna, 1993) that developes an internal transport barrier is analysed for the transport of ion energy and momentum. First, the classical ion temperature gradient stability properties are calculated in the absence of sheared plasma flows to establish the L-mode transport level prior to the emergence of the transport barrier. Then the evolving toroidal and poloidal velocity profiles reported by Koide et al (1994 Phys. Rev. Lett. 72 3662) are used to show how the sheared mass flows control the stability and transport. Coupled energy-momentum transport equations predict the creation of a transport barrier. The balance of the steep ion temperature gradient against the magnetic shear and sheared mass flow is calculated for the profiles in the 17110 discharge. (Author)

  12. Experimental aspects of ion acceleration and transport in the Earth's magnetosphere

    International Nuclear Information System (INIS)

    Young, D.T.

    1985-01-01

    Major particle population within the Earth's magnetosphere have been studied via ion acceleration processes. Experimental advances over the past ten to fifteen years have demonstrated the complexity of the processes. A review is given here for areas where composition experiments have expanded perception on magnetospheric phenomena. 64 refs., 6 figs., 1 tab

  13. Transport of heavy ions in inertial confinement fusion

    International Nuclear Information System (INIS)

    Parvazian, A.; Shahbandari Gouchani, A.

    2007-01-01

    In this article we have investigated the interaction of heavy ions (U) with a target (Au). In inertial confinement fusion method Interaction between heavy ion beam and target was simulated, Numerical analysis of the Boltzmann Fokker Planck equation used in order to optimize the material of the target and Energy deposition of ion beam to electrons and ions of target and The thickness of the target were calculated.

  14. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Directory of Open Access Journals (Sweden)

    Elena García-Giménez

    2012-01-01

    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  15. Ion Transport in Organic Electrolyte Solution through the Pore Channels of Anodic Nanoporous Alumina Membranes

    International Nuclear Information System (INIS)

    Fukutsuka, Tomokazu; Koyamada, Kohei; Maruyama, Shohei; Miyazaki, Kohei; Abe, Takeshi

    2016-01-01

    Highlights: • Ion transport in organic electrolyte solution in macro- and meso-pores was focused. • Anodic nanoporous alumina membrane was used as a porous material. • The specific ion conductivities drastically decreased in macro- and meso-pores. - Abstract: For the development of high energy density lithium-ion batteries with the high rate performance, the enhancement of the ion transport in the electrolyte solutions impregnated in the porous electrodes is a key. To study the ion transport in porous electrodes, anodic nanoporous alumina (APA) self-standing membranes with macro- or meso-pores were used as model porous materials. These membranes had nearly spherical pore channels of discrete 20–68 nm in diameters. By using the geometric shape of the pores, we attempted to evaluate the specific ion conductivities of the organic electrolyte solution dissolving lithium salt simply. AC impedance spectroscopy measurement of a four-electrode cell with membranes showed one depressed semi-circle in the Nyquist plots and this semi-circle can be assigned as the ion transport resistance in the pores. The specific ion conductivities evaluated from the ion transport resistances and the geometric parameters showed very small values, even in the macro-pores, as compared with that of the bulk electrolyte solution.

  16. Isolation of ionospheres from ion transport systems and their role in energy transduction

    Energy Technology Data Exchange (ETDEWEB)

    Shamoo, A E; Goldstein, D A

    1977-01-01

    In the past twenty-five years cell membrane transport has been studied from the point of view of kinetics and the biochemical correlation of enzyme function with that of transport. Artificial lipid bilayers have been used as a model for cell membrane transport. Antibiotics, such as valinomycin have also been studied as models of ion-transport mediators. Much effort has been invested on the study of model compounds as the possible molecular bases of transport. Information derived from the study of model systems throughout the years has been valuable and worthwhile. However, if the aim is to elucidate the mechanism of cell membrane transport, the time has come to merge the two lines of research into one and to shift emphasis from the study of model systems to the study of isolated transport machine components before and after reconstitution of its components into model membranes. These studies should be augmented at all times with the biochemical correlates of the transport proteins. A review is presented of the new avenues employed to elucidate the molecular mechanism of active transport. The new avenues are those of isolation of ion-transport mediators (ionophores) from membrane transport proteins. Reconstitution of ionophores and the various membrane transport proteins into artificial systems such as bilayers and vesicles presents a powerful tool to elucidate the molecular mechanism of active transport. More importantly, the new approach provides the first glimpse of evidence for a reasonable investigation of energy transduction from ATP hydrolysis to transport of an ion.

  17. The Hydrogen Peroxide Scavenger, Catalase, Alleviates Ion Transport Dysfunction in Murine Colitis

    Science.gov (United States)

    Barrett, Kim E.; McCole, Declan F.

    2016-01-01

    Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) contribute to epithelial damage and ion transport dysfunction (key events in inflammatory diarrhea) in inflammatory bowel disease (IBD). The aim of this study was to identify if H2O2 mediates suppression of colonic ion transport function in the murine dextran sulfate sodium (DSS) colitis model by using the H2O2 degrading enzyme, catalase. Colitis was induced by administering DSS (4%) in drinking water for 5 days followed by 3 days on normal H2O. Mice were administered either pegylated-catalase or saline at day −1, 0 and +1 of DSS treatment. Ion transport responses to the Ca2+-dependent agonist, carbachol (CCh), or the cAMP-dependent agonist, forskolin, were measured across distal colonic mucosa mounted in Ussing chambers. Parameters of DSS-induced inflammation (loss in body weight, decreased colon length, altered stool consistency), were only partially alleviated by catalase while histology was only minimally improved. However, catalase significantly reversed the DSS-induced reduction in baseline ion transport as well as colonic Isc responses to CCh. However, ion transport responses to forskolin were not significantly restored. Catalase also reduced activation of ERK MAP kinase in the setting of colitis, and increased expression of the Na+-K+-2Cl− cotransporter, NKCC1, consistent with restoration of ion transport function. Ex vivo treatment of inflamed colonic mucosae with catalase also partially restored ion transport function. Therefore, catalase partially prevents, and rescues, the loss of ion transport properties in DSS colitis even in the setting of unresolved tissue inflammation. These findings indicate a prominent role for ROS in ion transport dysfunction in colitis and may suggest novel strategies for the treatment of inflammatory diarrhea. PMID:27543846

  18. Hydrogen peroxide scavenger, catalase, alleviates ion transport dysfunction in murine colitis.

    Science.gov (United States)

    Barrett, Kim E; McCole, Declan F

    2016-11-01

    Reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ) contribute to epithelial damage and ion transport dysfunction (key events in inflammatory diarrhoea) in inflammatory bowel disease (IBD). The aim of this study was to identify if H 2 O 2 mediates suppression of colonic ion transport function in the murine dextran sulfate sodium (DSS) colitis model by using the H 2 O 2 degrading enzyme, catalase. Colitis was induced by administering DSS (4%) in drinking water for 5 days followed by 3 days on normal H 2 O. Mice were administered either pegylated catalase or saline at day -1, 0 and +1 of DSS treatment. Ion transport responses to the Ca 2+ -dependent agonist, carbachol (CCh), or the cAMP-dependent agonist, forskolin, were measured across distal colonic mucosa mounted in Ussing chambers. Parameters of DSS-induced inflammation (loss in body weight, decreased colon length, altered stool consistency), were only partially alleviated by catalase while histology was only minimally improved. However, catalase significantly reversed the DSS-induced reduction in baseline ion transport as well as colonic I sc responses to CCh. However, ion transport responses to forskolin were not significantly restored. Catalase also reduced activation of ERK MAP kinase in the setting of colitis, and increased expression of the Na + -K + -2Cl - cotransporter, NKCC1, consistent with restoration of ion transport function. Ex vivo treatment of inflamed colonic mucosae with catalase also partially restored ion transport function. Therefore, catalase partially prevents, and rescues, the loss of ion transport properties in DSS colitis even in the setting of unresolved tissue inflammation. These findings indicate a prominent role for ROS in ion transport dysfunction in colitis and may suggest novel strategies for the treatment of inflammatory diarrhoea. © 2016 John Wiley & Sons Australia, Ltd.

  19. Surprising phenomena at the surface of solids: complex molecule emission after impact of ions or of energetic photons

    International Nuclear Information System (INIS)

    Le Beyec, Y.

    1990-01-01

    The vanishing of large mass molecules, by particle or photon impact is an unexpected behavior of the matter which allows to study the medium answer to the interaction. This phenomenon has several applications and gives rise development of analysis scientific instrumentation for non volatile compounds as the time of flight mass spectrometers. - In this report, the point is made about the induced desorption by rapid heavy ions [fr

  20. Small scale laboratory studies of flow and transport phenomena in pores and fractures: Phase II. Progress report, 3rd year continuation proposal, and work plan

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J.L.

    1994-05-01

    Small scale laboratory experiments, equipped with an ability to actually observe behavior on the pore level using microscopy, provide an economical and easily understood scientific tool to help us validate concepts and assumptions about the transport of contaminants, and offers the propensity to discover heretofore unrecognized phenomena or behavior. The main technique employs etched glass micromodels, composed of two etched glass plates, sintered together, to form a two dimensional network of three dimensional pores. Flow and transport behavior is observed on a pore or pore network level, and recorder on film and video tape. This technique is coupled with related column studies. These techniques have been used to study multiphase flow, colloid transport and most recently bacteria transport. The project has recently moved to the Bacteria Transport Subprogram, and efforts have been redirected to support that Subprogram and its collaborative field experiment. We proposed to study bacteria transport factors of relevance to the field experiment, using micromodels and other laboratory techniques. Factors that may be addressed include bacteria characteristics (eg, hydrophobicity), pore size and shape, permeability heterogeneity, surface chemistry (eg, iron oxide coatings), surface chemistry heterogeneity, active versus resting cell bacteria, and mixed bacteria populations. In other work we will continue to examine the effects of fluid-fluid interfaces on bacteria transport, and develop a new assay for bacteria hydrophobicity. Finally we will collaborate on characterization of the field site, and the design, operation, and interpretation of the field experiment.

  1. Modulation of ion transport across rat distal colon by cysteine

    Directory of Open Access Journals (Sweden)

    Martin eDiener

    2012-03-01

    Full Text Available The aim of this study was to identify the actions of stimulation of endogenous production of H2S by cysteine, the substrate for the two H2S-producing enzymes, cystathionin-beta-synthase and cystathionin-gamma-lyase, on ion transport across rat distal colon. Changes in short-circuit current (Isc induced by cysteine were measured in Ussing chambers. Free cysteine caused a concentration-dependent, transient fall in Isc, which was sensitive to amino-oxyacetate and beta-cyano-L-alanine, i.e. inhibitors of H2S-producing enzymes. In contrast, Na cysteinate evoked a biphasic change in Isc, i.e. an initial fall followed by a secondary increase, which was also reduced by these enzyme inhibitors. All responses were dependent on the presence of Cl- and inhibited by bumetanide, suggesting that free cysteine induces an inhibition of transcellular Cl- secretion, whereas Na cysteinate – after a transient inhibitory phase – activates anion secretion. The assumed reason for this discrepancy is a fall in the cytosolic pH induced by free cysteine, but not by Na cysteinate, as observed in isolated colonic crypts loaded with the pH-sensitive dye, BCECF. Intracellular acidification is known to inhibit epithelial K+ channels. Indeed, after preinhibition of basolateral K+ channels with tetrapentylammonium or Ba2+, the negative Isc induced by free cysteine was reduced significantly. In consequence, stimulation of endogenous H2S production by Na cysteinate causes, after a short inhibitory response, a delayed activation of anion secretion, which is missing in the case of free cysteine, probably due to the cytosolic acidification. In contrast, diallyl trisulfide, which is intracellularly converted to H2S, only evoked a monophasic increase in Isc without the initial fall observed with Na cysteinate. Consequently, time course and amount of produced H2S seem to strongly influence the functional response of the colonic epithelium evoked by this gasotransmitter.

  2. Evaluation of spectroscopic modeling for iron ions and study on non-equilibrium ionization phenomena for solar and LHD plasmas

    International Nuclear Information System (INIS)

    Watanabe, Tetsuya; Hara, Hirohisa; Yamamoto, Norimasa; Kato, Daiji; Sakaue, Hiroyuki A.; Murakami, Izumi

    2013-01-01

    Spectroscopic observations of EUV emission lines in the transition region (TR) and the corona provide unique information on physical conditions in the outer atmosphere of the Sun. The EUV Imaging Spectrometer (EIS) on board the Hinode satellite is capable of observing, for the first time in EUV, spectra and monochromatic images of plasmas in the solar TR and corona; these plasmas could possibly be in non-ionization-equilibrium conditions. EIS observes over two-wavelength bands of 170 - 210 Å and 250 - 290 Å, with typical time-resolutions of 1 - 10 seconds. Iron line emissions emerging from these wavelengths reveal that dynamic plasma accelerations and heating take place in the solar atmosphere. On the other hand, the tracer-encapsulated-pellet (TESPEL) experiments provide spectral information of EUV emission lines from iron ions produced in the Large Helical Device (LHD). Relatively cool plasmas with electron temperatures similar to those of the solar corona can be generated by controlling the neutral beam injector (NBI) system. A time-dependent collisional radiative (CR) model for elemental iron is developed as a common tool to diagnose temperatures and densities of those plasmas in the Sun and in LHD; no systematic model yet exists for iron ions in the L- and M-shell ionization stages, which are very important for coronal plasma diagnostics. Adopting the best available theoretical calculations, as well as generating the experimental data, we improve the atomic parameters of highly charged iron ions, and these results are used to extract more accurate diagnostic information out of the EIS spectra. (author)

  3. Analysis of the ion energy transport in ohmic discharges in the ASDEX tokamak

    International Nuclear Information System (INIS)

    Simmet, E.E.; Fahrbach, H.U.; Herrmann, W.; Stroth, U.

    1996-10-01

    An analysis of the local ion energy transport is performed for more than one hundred well documented ohmic ASDEX discharges. These are characterized by three different confinement regimes: the linear ohmic confinement (LOC), the saturated ohmic confinement (SOC) and the improved ohmic confinement (IOC). All three are covered by this study. To identify the most important local transport mechanism of the ion heat, the ion power balance equation is analyzed. Two methods are used: straightforward calculation with experimental data only, and a comparison of measured and calculated profiles of the ion temperature and the ion heat conductivity, respectively. A discussion of the power balance shows that conductive losses dominate the ion energy transport in all ohmic discharges of ASDEX. Only inside the q=1-surface losses due to sawtooth activity play a role, while at the edge convective fluxes and CX-losses influence the ion energy transport. Both methods lead to the result that both the ion temperature and the ion heat conductivity are consistent with predictions of the neoclassical theory. Enhanced heat losses as suggested by theories eg. on the basis of η i modes can be excluded. (orig.)

  4. Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

    KAUST Repository

    Sethuraman, Vaidyanathan

    2017-10-23

    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  5. Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

    KAUST Repository

    Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

    2017-01-01

    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  6. Integrated heat transport simulation of high ion temperature plasma of LHD

    International Nuclear Information System (INIS)

    Murakami, S.; Yamaguchi, H.; Sakai, A.

    2014-10-01

    A first dynamical simulation of high ion temperature plasma with carbon pellet injection of LHD is performed by the integrated simulation GNET-TD + TASK3D. NBI heating deposition of time evolving plasma is evaluated by the 5D drift kinetic equation solver, GNET-TD and the heat transport of multi-ion species plasma (e, H, He, C) is studied by the integrated transport simulation code, TASK3D. Achievement of high ion temperature plasma is attributed to the 1) increase of heating power per ion due to the temporal increase of effective charge, 2) reduction of effective neoclassical transport with impurities, 3) reduction of turbulence transport. The reduction of turbulence transport is most significant contribution to achieve the high ion temperature and the reduction of the turbulent transport from the L-mode plasma (normal hydrogen plasma) is evaluated to be a factor about five by using integrated heat transport simulation code. Applying the Z effective dependent turbulent reduction model we obtain a similar time behavior of ion temperature after the C pellet injection with the experimental results. (author)

  7. Transport coefficients of gaseous ions in an electric field

    Science.gov (United States)

    Whealton, J. H.; Mason, E. A.

    1974-01-01

    A general theory of ion mobility formulated by Kihara (1953) is extended to ion diffusion and to mixtures of neutral gases. The theory assumes that only binary collisions between ions and neutral particles need to be taken into account and that the velocity distribution function of the neutral particles is Maxwellian. These assumptions make it possible to use a linearized Boltzmann equation. Questions of mobility are considered along with aspects of diffusion and deviations from Fick's law of diffusion.

  8. Behavior of electron and ion transport in discharges with an internal transport barrier in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Greenfield, C.M.; Staebler, G.M.; Rettig, C.L.

    1999-01-01

    We report results of experiments to further determine the underlying physics behind the formation and development of internal transport barriers (ITB) in the DIII-D tokamak. The initial ITB formation occurs when the neutral beam heating power exceeds a threshold value during the early stages of the current ramp in low-density discharges. This region of reduced transport, made accessible by suppression of long-wavelength turbulence by sheared flows, is most evident in the ion temperature and impurity rotation profiles. In some cases, reduced transport is also observed in the electron temperature and density profiles. If the power is near the threshold, the barrier remains stationary and encloses only a small fraction of the plasma volume. If, however, the power is increased, the transport barrier expands to encompass a larger fraction of the plasma volume. The dynamic behavior of the transport barrier during the growth phase exhibits rapid transport events that are associated with both broadening of the profiles and reductions in turbulence and associated transport. In some, but not all, cases, these events are correlated with the safety factor q passing through integer values. The final state following this evolution is a plasma exhibiting ion thermal transport at or below neoclassical levels. Typically, the electron thermal transport remains anomalously high. Recent experimental results are reported in which rf electron heating was applied to plasmas with an ion ITB, thereby increasing both the electron and ion transport. Although the results are partially in agreement with the usual E-vector x B-vector shear suppression hypothesis, the results still leave questions that must be addressed in future experiments. (author)

  9. Behavior of electron and ion transport in discharges with an internal transport barrier in the DIII-D tokamak

    International Nuclear Information System (INIS)

    Greenfield, C.M.; Staebler, G.M.; Rettig, C.L.

    1998-12-01

    The authors report results of experiments to further determine the underlying physics behind the formation and development of internal transport barriers (ITB) in the DIII-D tokamak. The initial ITB formation occurs when the neutral beam heating power exceeds a threshold value during the early stages of the current ramp in low-density discharges. This region of reduced transport, made accessible by suppression of long-wavelength turbulence by sheared flows, is most evident in the ion temperature and impurity rotation profiles. In some cases, reduced transport is also observed in the electron temperature and density profiles. If the power is near the threshold, the barrier remains stationary and enclosed only a small fraction of the plasma volume. If, however, the power is increased, the transport barrier expands to encompass a larger fraction of the plasma volume. The dynamic behavior of the transport barrier during the growth phase exhibits rapid transport events that are associated with both broadening of the profiles and reductions in turbulence and associated transport. In some, but not all, cases, these events are correlated with the safety factor q passing through integer values. The final state following this evolution is a plasma exhibiting ion thermal transport at or below neoclassical levels. Typically, the electron thermal transport remains anomalously high. Recent experimental results are reported in which rf electron heating was applied to plasmas with an ion ITB, thereby increasing both the electron and ion transport. Although the results are partially in agreement with the usual rvec E x rvec B shear suppression hypothesis, the results still leave questions that must be addressed in future experiments

  10. Comparisons of theoretically predicted transport from ion temperature gradient instabilities to L-mode tokamak experiments

    International Nuclear Information System (INIS)

    Kotschenreuther, M.; Wong, H.V.; Lyster, P.L.; Berk, H.L.; Denton, R.; Miner, W.H.; Valanju, P.

    1991-12-01

    The theoretical transport from kinetic micro-instabilities driven by ion temperature gradients is a sheared slab is compared to experimentally inferred transport in L-mode tokamaks. Low noise gyrokinetic simulation techniques are used to obtain the ion thermal transport coefficient X. This X is much smaller than in experiments, and so cannot explain L-mode confinement. Previous predictions based on fluid models gave much greater X than experiments. Linear and nonlinear comparisons with the fluid model show that it greatly overestimates transport for experimental parameters. In addition, disagreements among previous analytic and simulation calculations of X in the fluid model are reconciled

  11. Beamline for low-energy transport of highly charged ions at HITRAP

    International Nuclear Information System (INIS)

    Andelkovic, Z.; Herfurth, F.; Kotovskiy, N.; König, K.; Maaß, B.; Murböck, T.; Neidherr, D.; Schmidt, S.; Steinmann, J.; Vogel, M.; Vorobjev, G.

    2015-01-01

    A beamline for transport of highly charged ions with energies as low as a few keV/charge has been constructed and commissioned at GSI. Complementary to the existing infrastructure of the HITRAP facility for deceleration of highly charged ions from the GSI accelerator, the new beamline connects the HITRAP ion decelerator and an EBIT with the associated experimental setups. Therefore, the facility can now transport the decelerated heavy highly charged ions to the experiments or supply them offline with medium-heavy highly charged ions from the EBIT, both at energies as low as a few keV/charge. Here we present the design of the 20 m long beamline with the corresponding beam instrumentation, as well as its performance in terms of energy and transport efficiency

  12. Ion transporters involved in acidification of the resorption lacuna in osteoclasts

    DEFF Research Database (Denmark)

    Henriksen, K.; Sorensen, M.G.; Jensen, V.K.

    2008-01-01

    Osteoclasts possess a large amount of ion transporters, which participate in bone resorption; of these, the vacuolar-adenosine trisphosphatase (V-ATPase) and the chloride-proton antiporter ClC-7 acidify the resorption lacuna. However, whether other ion transporters participate in this process is ......, including carbonic anhydrase II, the NHEs, and potassium-chloride cotransporters, are all involved in resorption but do not seem to directly be involved in acidification of the lysosomes Udgivelsesdato: 2008/9......Osteoclasts possess a large amount of ion transporters, which participate in bone resorption; of these, the vacuolar-adenosine trisphosphatase (V-ATPase) and the chloride-proton antiporter ClC-7 acidify the resorption lacuna. However, whether other ion transporters participate in this process...

  13. Beam diagnostics and data acquisition system for ion beam transport line used in applied research

    International Nuclear Information System (INIS)

    Skuratov, V.A.; Didyk, A.Yu.; Arkhipov, A.V.; Illes, A.; Bodnar, K.; Illes, Z.; Havancsak, K.

    1999-01-01

    Ion beam transport line for applied research on U-400 cyclotron, beam diagnostics and data acquisition system for condensed matter studies are described. The main features of Windows-based real time program are considered

  14. Surface oxygen vacancy and oxygen permeation flux limits of perovskite ion transport membranes

    KAUST Repository

    Hunt, Anton; Dimitrakopoulos, Georgios; Ghoniem, Ahmed F.

    2015-01-01

    © 2015 Elsevier B.V. The mechanisms and quantitative models for how oxygen is separated from air using ion transport membranes (ITMs) are not well understood, largely due to the experimental complexity for determining surface exchange reactions

  15. Kinetic effects on magnetohydrodynamic phenomena

    International Nuclear Information System (INIS)

    Naito, Hiroshi; Matsumoto, Taro

    2001-01-01

    Resistive and ideal magnetohydrodynamic (MHD) theories are insufficient to adequately explain MHD phenomena in the high-temperature plasma. Recent progress in numerical simulations concerning kinetic effects on magnetohydrodynamic phenomena is summarized. The following three topics are studied using various models treating extended-MHD phenomena. (1) Kinetic modifications of internal kink modes in tokamaks with normal and reversed magnetic shear configurations. (2) Temporal evolution of the toroidal Alfven eigenmode and fishbone mode in tokamaks with energetic ions. (3) Kinetic stabilization of a title mode in field-reversed configurations by means of anchoring ions and beam ions. (author)

  16. Transport theory of dissipative heavy-ion collisions

    International Nuclear Information System (INIS)

    Noerenberg, W.

    1979-03-01

    The lectures present the formulation of a transport theory, the derivation of a practicable transport equation (Fokker-Planck equation) and the evaluation of transport coefficients for dissipative (or deeply inelastic) heavyion collisions. The applicability of the theoretical concept is tested with remarkable success in the analyses of various experimental informations (mass transfer, angular-momentum dissipation and energy loss). Some critical remarks on the present situation of transport theories are added. Future developments are outlined. (orig.) [de

  17. Transport of Alkali Metal Ions through a Liquid Membrane System ...

    African Journals Online (AJOL)

    crown-6, [K(MF18C6)](picrate) was determined by X-ray crystallography and showed that each potassium ion is eight-coordinate; each K+ ion is coordinated to the six oxygen atoms of the crown, to the phenolate oxygen atom and to one of the ...

  18. Transport and extraction of radioactive ions stopped in superfluid helium

    NARCIS (Netherlands)

    Huang, WX; Dendooven, P; Gloos, K; Takahashi, N; Arutyunov, K; Pekola, JP; Aysto, J

    A new approach to convert a high energy beam to a low energy one, which is essential for the next generation radioactive ion beam facilities, has been proposed and tested at Jyvaskyla, Finland. An open Ra-223 alpha-decay-recoil source has been used to produce radioactive ions in superfluid helium.

  19. Ion-neutral transport through quadrupole interfaces of mass-spectrometer systems

    International Nuclear Information System (INIS)

    Jugroot, M.; Groth, C.P.T.; Thomson, B.A.; Baranov, V.; Collings, B.A.; French, J.B.

    2004-01-01

    The transport of free ions through highly under-expanded jet flows of neutral gases and in the presence of applied electric fields is investigated by continuum-based numerical simulations. In particular, numerical results are described which are relevant to ion flows occurring in quadrupole interfaces of mass spectrometer systems. A five-moment mathematical model and parallel multi-block numerical solution procedure is developed for predicting the ion transport. The model incorporates the effects of ion-neutral collision processes and is used in conjunction with a Navier-Stokes model and flow solver for the neutral gas to examine the key influences controlling the ion motion. The effects of the neutral gas flow, electric fields (both dc and rf), and flow field geometry on ion mobility are carefully assessed. The capability of controlling the charged particle motions through a combination of directed neutral flow and applied electric field is demonstrated for these high-speed, hypersonic, jet flows. (author)

  20. Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho; Hong, In-Seok [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of)

    2016-02-15

    A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, development of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.

  1. Temperature dependent dielectric properties and ion transportation in solid polymer electrolyte for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sengwa, R. J., E-mail: rjsengwa@rediffmail.com; Dhatarwal, Priyanka, E-mail: dhatarwalpriyanka@gmail.com; Choudhary, Shobhna, E-mail: shobhnachoudhary@rediffmail.com [Dielectric Research Laboratory, Department of Physics, Jai Narain Vyas University, Jodhpur – 342 005 (India)

    2016-05-06

    Solid polymer electrolyte (SPE) film consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrix with lithium tetrafluroborate (LiBF{sub 4}) as dopant ionic salt and poly(ethylene glycol) (PEG) as plasticizer has been prepared by solution casting method followed by melt pressing. Dielectric properties and ionic conductivity of the SPE film at different temperatures have been determined by dielectric relaxation spectroscopy. It has been observed that the dc ionic conductivity of the SPE film increases with increase of temperature and also the decrease of relaxation time. The temperature dependent relaxation time and ionic conductivity values of the electrolyte are governed by the Arrhenius relation. Correlation observed between dc conductivity and relaxation time confirms that ion transportation occurs with polymer chain segmental dynamics through hopping mechanism. The room temperature ionic conductivity is found to be 4 × 10{sup −6} S cm{sup −1} which suggests the suitability of the SPE film for rechargeable lithium batteries.

  2. Transport of a multiple ion species plasma in the Pfirsch--Schluter regime

    International Nuclear Information System (INIS)

    Hirshman, S.P.

    1976-10-01

    The classical parallel friction coefficients, which relate the collisional friction forces to the flow of particles and heat along the magnetic field, are calculated for a multiple ion species plasma. In the short mean free path regime, the neoclassical Pfirsch--Schlueter transport coefficients for a toroidally confined multispecies plasma are computed in terms of the classical friction coefficients. The dependence of the neoclassical cross-field transport on the equilibration of the parallel ion temperature profiles is determined

  3. Solvent effect on the extraction and transport of lithium ions by polyethylene glycols

    International Nuclear Information System (INIS)

    Mishra, D; Sharma, U

    1999-01-01

    Extraction of lithium picrate, 2,4-dinitrophenolate and 2-nitrophenolate and their transport through membranes by di-, tri- and tetraethylene glycols as carriers are studied. Organic solvents considered as extractants and liquid membranes in terms of lithium ions extraction and transfer are arranged in the following series: methylene chloride ≥ dichloroethane ≥ chloroform ≥ carbon tetrachloride. Diethylene glycol proved the most effective solvent for lithium ions extraction and transport [ru

  4. Chamber-transport simulation results for heavy-ion fusion drivers

    International Nuclear Information System (INIS)

    Sharp, W M; Callahan, D A; Tabak, M; Yu, S S; Peterson, P F; Rose, D V; Welch, D R

    2004-01-01

    The heavy-ion fusion (HIF) community recently developed a power-plant design that meets the various requirements of accelerators, final focus, chamber transport, and targets. The point design is intended to minimize physics risk and is certainly not optimal for the cost of electricity. Recent chamber-transport simulations, however, indicate that changes in the beam ion species, the convergence angle, and the emittance might allow more-economical designs

  5. The gyro-radius scaling of ion thermal transport from global numerical simulations of ITG turbulence

    International Nuclear Information System (INIS)

    Ottaviani, M.; Manfredi, G.

    1998-12-01

    A three-dimensional, fluid code is used to study the scaling of ion thermal transport caused by Ion-Temperature-Gradient-Driven (ITG) turbulence. The code includes toroidal effects and is capable of simulating the whole torus. It is found that both close to the ITG threshold and well above threshold, the thermal transport and the turbulence structures exhibit a gyro-Bohm scaling, at least for plasmas with moderate poloidal flow. (author)

  6. Transport of negative ions across a double sheath with a virtual cathode

    International Nuclear Information System (INIS)

    McAdams, R; King, D B; Surrey, E; Holmes, A J T

    2011-01-01

    A one-dimensional analytical model of the sheath in a negative ion source, such as those proposed for heating and diagnostic beams on present and future fusion devices, has been developed. The model, which is collisionless, describes the transport of surface produced negative ions from a cathode, across the sheath to a plasma containing electrons, positive ions and negative ions. It accounts for the situation where the emitted flux of negative ions is greater than the space charge limit, where the electric field at the cathode is negative, and a virtual cathode is formed. It is shown that, in the presence of a virtual cathode, there is a maximum current density of negative ions that can be transported across the sheath into the plasma. Furthermore, for high rates of surface production the virtual cathode persists regardless of the negative bias applied to the cathode, so that the current density transported across the sheath is limited. This is a significant observation and implies that present negative ion sources may not be exploiting all of the surface production available. The model is used to calculate the transported negative ion flux in a number of examples. The limitations of the model and proposed future work are also discussed.

  7. The wondrous world of transport and acceleration of intense ion beams

    International Nuclear Information System (INIS)

    Siebenlist, F.

    1987-01-01

    A theoretical and experimental study of the transport, bunching and acceleration of intense ion beams in periodic focusing channels is described. The aim is to show the feasibility of accelerating high current ion beams with a Multiple Electrostatic Quadrupole Array Linear ACcelerator (MEQALAC). 83 refs.; 51 figs.; 3 tabs

  8. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane

    Directory of Open Access Journals (Sweden)

    A. G. Gaikwad

    2012-06-01

    Full Text Available Transport of carbonate ions was explored through fiber supported solid membrane. A novel fiber supported solid membrane was prepared by chemical modification of cellulose fiber with citric acid, 2′2-bipyridine and magnesium carbonate. The factors affecting the permeability of carbonate ions such as immobilization of citric acid-magnesium metal ion -2′2-bipyridine complex (0 to 2.5 mmol/g range over cellulose fiber, carbon-ate ion concentration in source phase and NaOH concentration in receiving phase were investigated. Ki-netic of carbonate, sulfate, and nitrate ions was investigated through fiber supported solid membrane. Transport of carbonate ions with/without bubbling of CO2 (0 to 10 ml/min in source phase was explored from source to receiving phase. The novel idea is to explore the adsorptive transport of CO2 from source to receiving phase through cellulose fiber containing magnesium metal ion organic framework. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 25th November 2011; Revised: 17th December 2011; Accepted: 19th December 2011[How to Cite: A.G. Gaikwad. (2012. Transport of Carbonate Ions by Novel Cellulose Fiber Supported Solid Membrane. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 49– 57.  doi:10.9767/bcrec.7.1.1225.49-57][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1225.49-57 ] | View in 

  9. Strong dopant dependence of electric transport in ion-gated MoS2

    NARCIS (Netherlands)

    Piatti, Erik; Chen, Qihong; Ye, Jianting

    2017-01-01

    We report modifications of the temperature-dependent transport properties of MoS2 thin flakes via field-driven ion intercalation in an electric double layer transistor. We find that intercalation with Li+ ions induces the onset of an inhomogeneous superconducting state. Intercalation with K+ leads

  10. Silicon transport in sputter-deposited tantalum layers grown under ion bombardment

    International Nuclear Information System (INIS)

    Gallais, P.; Hantzpergue, J.J.; Remy, J.C.; Roptin, D.

    1988-01-01

    Tantalum was sputter deposited on (111) Si substrate under low-energy ion bombardment in order to study the effects of the ion energy on the silicon transport into the Ta layer. The Si substrate was heated up to 500 0 C during growth. For ion energies up to 180 eV silicon is not transported into tantalum and the growth temperature has no effect. An ion bombardment energy of 280 eV enhances the transport of silicon throughout the tantalum layer. Growth temperatures up to 300 0 C have no effect on the silicon transport which is mainly enhanced by the ion bombardment. For growth temperatures between 300 and 500 0 C, the silicon transport is also enhanced by the thermal diffusion. The experimental depth distribution of silicon is similar to the theoretical depth distribution calculated for the case of an interdiffusion. The ion-enhanced process of silicon transport is characterized by an activation energy of 0.4 eV. Silicon into the layers as-grown at 500 0 C is in both states, amorphous silicide and microcrystalline cubic silicon

  11. Transition flow ion transport via integral Boltzmann equation

    International Nuclear Information System (INIS)

    Darcie, T.E.

    1983-10-01

    A new approach is developed to solve the Integral Boltzmann Equation for the evolving velocity distribution of a source of ions, undergoing electrostatic acceleration through a neutral gas target. The theory is applicable to arbitrarily strong electric fields, any ion/neutral mass ratio greater than unity, and is not limited to spatially isotropic gas targets. A hard sphere collision model is used, with a provision for inelasticity. Both axial and radial velocity distributions are calculated for applications where precollision radial velocities are negligible, as is the case for ion beam extractions from high pressure sources. Theoretical predictions are tested through an experiment in which an atmospheric pressure ion source is coupled to a high vacuum energy analyser. Excellent agreement results for configurations in which the radial velocity remains small. Velocity distributions are applied to predicting the efficiency of coupling an atmospheric pressure ion source to a quadrupole mass spectrometer and results clearly indicate the most desirable extracting configuration. A method is devised to calculate ion-molecule hard sphere collision cross sections for easily fragmented organic ions

  12. Maxima and minima of the orientation phenomena for direct 1s→2p+-1 electron-ion collisional excitations in weakly coupled plasmas

    International Nuclear Information System (INIS)

    Yoon Jung-Sik; Jung Young-Dae

    1999-01-01

    Orientation phenomena for direct 1s→2p +-1 electron-ion collisional excitations in weakly coupled plasma are investigated using the semiclassical trajectory method including the close-encounter effects. In weakly coupled plasmas, the electron-ion interaction potential is given by the classical nonspherical Debye-Hueckel model. The semiclassical screened hyperbolic-orbit trajectory method is applied to describe the motion of the projectile electron in order to investigate the variation of the orientation parameter as a function of the impact parameter, projectile energy, and Debye length. A comparison is also given for the hyperbolic-orbit and straight-line trajectory methods. The results show that the orientation parameters obtained by the hyperbolic-orbit trajectory method have maxima and minima for small impact parameter regions. In other words, there are complete 1s→2p +1 (maxima) and complete 1s→2p -1 (minima) transitions for certain impact parameters. These maxima cannot be found using the straight-line trajectory method. The variation of the propensity of the 1s→2p -1 transitions due to the plasma screening effects on the atomic wave functions is also discussed

  13. Transport and acceleration of the high-current ion beam in magneto-isolated gap

    International Nuclear Information System (INIS)

    Karas', V.I.; Kornilov, E.A.; Manuilenko, O.V.; Fedorovskaya, O.V.; Tarakanov, V.P.

    2015-01-01

    The possibility of transportation and acceleration of the high-current ion beam in the magneto-isolated gap has been demonstrated. Found the parameters of the system and beams (the magnetic field produced by the coils with opposing currents, the size of the system, and the parameters of the beams), under which the uniform acceleration of the high-current ion beam all along the gap length is realized. It is shown that the quality of the ion beam, during transport and acceleration, at the exit of the gap is acceptable for many technological applications.

  14. Metal ion transport quantified by ICP-MS in intact cells

    Science.gov (United States)

    Figueroa, Julio A. Landero; Stiner, Cory A.; Radzyukevich, Tatiana L.; Heiny, Judith A.

    2016-01-01

    The use of ICP-MS to measure metal ion content in biological tissues offers a highly sensitive means to study metal-dependent physiological processes. Here we describe the application of ICP-MS to measure membrane transport of Rb and K ions by the Na,K-ATPase in mouse skeletal muscles and human red blood cells. The ICP-MS method provides greater precision and statistical power than possible with conventional tracer flux methods. The method is widely applicable to studies of other metal ion transporters and metal-dependent processes in a range of cell types and conditions. PMID:26838181

  15. Integral Transport Analysis Results for Ions Flowing Through Neutral Gas

    Science.gov (United States)

    Emmert, Gilbert; Santarius, John

    2017-10-01

    Results of a computational model for the flow of energetic ions and neutrals through a background neutral gas will be presented. The method models reactions as creating a new source of ions or neutrals if the energy or charge state of the resulting particle is changed. For a given source boundary condition, the creation and annihilation of the various species is formulated as a 1-D Volterra integral equation that can quickly be solved numerically by finite differences. The present work focuses on multiple-pass, 1-D ion flow through neutral gas and a nearly transparent, concentric anode and cathode pair in spherical, cylindrical, or linear geometry. This has been implemented as a computer code for atomic (3He, 3He +, 3He + +) and molecular (D, D2, D-, D +, D2 +, D3 +) ion and neutral species, and applied to modeling inertial-electrostatic connement (IEC) devices. The code yields detailed energy spectra of the various ions and energetic neutral species. Calculations for several University of Wisconsin IEC and ion implantation devices will be presented. Research supported by US Dept. of Homeland Security Grant 2015-DN-077-ARI095, Dept. of Energy Grant DE-FG02-04ER54745, and the Grainger Foundation.

  16. Ion and metabolite transport in the chloroplast of algae: lessons from land plants.

    Science.gov (United States)

    Marchand, Justine; Heydarizadeh, Parisa; Schoefs, Benoît; Spetea, Cornelia

    2018-06-01

    Chloroplasts are endosymbiotic organelles and play crucial roles in energy supply and metabolism of eukaryotic photosynthetic organisms (algae and land plants). They harbor channels and transporters in the envelope and thylakoid membranes, mediating the exchange of ions and metabolites with the cytosol and the chloroplast stroma and between the different chloroplast subcompartments. In secondarily evolved algae, three or four envelope membranes surround the chloroplast, making more complex the exchange of ions and metabolites. Despite the importance of transport proteins for the optimal functioning of the chloroplast in algae, and that many land plant homologues have been predicted, experimental evidence and molecular characterization are missing in most cases. Here, we provide an overview of the current knowledge about ion and metabolite transport in the chloroplast from algae. The main aspects reviewed are localization and activity of the transport proteins from algae and/or of homologues from other organisms including land plants. Most chloroplast transporters were identified in the green alga Chlamydomonas reinhardtii, reside in the envelope and participate in carbon acquisition and metabolism. Only a few identified algal transporters are located in the thylakoid membrane and play role in ion transport. The presence of genes for putative transporters in green algae, red algae, diatoms, glaucophytes and cryptophytes is discussed, and roles in the chloroplast are suggested. A deep knowledge in this field is required because algae represent a potential source of biomass and valuable metabolites for industry, medicine and agriculture.

  17. Temperature fields occurring in dielectric capillaries for the transport of of ion beams

    International Nuclear Information System (INIS)

    Urbanovich, A.I.

    2012-01-01

    This paper presents the results of computing the temperature fields occurring in dielectric capillaries of glass for the transport of accelerated charged particles. It is shown that on the transport of ion beams with a power of several watts the capillary is heated intensively, whereas heat stresses may approach the lower bound associated with a real strength of glass. (authors)

  18. An initial study on atmospheric pressure ion transport by laser ionization and electrostatic fields.

    OpenAIRE

    Peralta Conde, Álvaro; Romero, Carolina; Boyero, Juan; Apiñaniz Aginako, Jon Imanol; Raposo Funcia, Cesar; Roso Franco, Luis; Padilla Moreno, Carlos Manuel

    2014-01-01

    Laser ionization of mixtures of gases at atmospheric pressure and the subsequent transport through electrostatic field is studied. A prototype is designed to perform the transport and detection of the ions. Relevance of the composition of the mixture of gases and ionization parameters is shown

  19. Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles.

    Science.gov (United States)

    Grzelczak, Marcin P; Danks, Stephen P; Klipp, Robert C; Belic, Domagoj; Zaulet, Adnana; Kunstmann-Olsen, Casper; Bradley, Dan F; Tsukuda, Tatsuya; Viñas, Clara; Teixidor, Francesc; Abramson, Jonathan J; Brust, Mathias

    2017-12-26

    Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported.

  20. Creation and dynamical co-evolution of electron and ion channel transport barriers

    International Nuclear Information System (INIS)

    Newman, D.E.

    2002-01-01

    A wide variety of magnetic confinement devices have found transitions to an enhanced confinement regime. Simple dynamical models have been able to capture much of the dynamics of these barriers however an open question has been the disconnected nature of the electron thermal transport channel sometimes observed in the presence of a standard ('ion channel' barrier. By adding to simple barrier model an evolution equation for electron fluctuations we can investigate the interaction between the formation of the standard ion channel barrier and the somewhat less common electron channel barrier. Barrier formation in the electron channel is even more sensitive to the alignment of the various gradients making up the sheared radial electric field than the ion barrier is. Electron channel heat transport is found to significantly increase after the formation of the ion channel barrier but before the electron channel barrier is formed. This increased transport is important in the barrier evolution. (author)

  1. Plasma flow between equipotential electrodes in an ion current transport mode

    International Nuclear Information System (INIS)

    Zimin, A.M.; Morozov, A.I.

    1995-01-01

    The paper deals with calculation of parameters in accelerator channel and near electrodes, when realizing ion current transport mode. Model on the basis of two-dimensional two-liquid nondissipative magnetohydrodynamics was formulated, and its solution for isomagnetic flow in smooth channel approximation was conducted. Change of parameters near anode surface was considered in detail. It is shown that regular joining of flow with equipotential electrodes without large near-electrode jumps is performed during ion current transport. Current distribution along accelerator length was calculated when determining ion intake through anode surface due to inertial-drift emission. It is shown that this mechanism can provide rather high current density in ion current transport. 10 refs.; 6 figs

  2. The role of biomembrane lipids in the molecular mechanism of ion transport radiation damage

    International Nuclear Information System (INIS)

    Medvedev, B.I.; Evtodienko, Yu.V.; Yaguzhinsky, L.S.; Kuzin, A.M.

    1977-01-01

    Increase in the rate of ATP synthesis (I.4-I.6 times), Ca 2+ -capacity (I.4-I.8 times), membrane potential (by 20-50 mv) and decrease in K - -conductivity (2.5-3 times) in rat liver mitochondria was observed three hours after γ-irradiation at a dose of 1000r. The process of oxidative phosphorylation was normalized 24 hours later, whereas damages of Ca 2+ -accumulation and K + -conductivity remain. The molecular mechanism of reduction in K + -permeability of mitochondrial membranes has been studied. The endogenous regulators of ionic transport in the lipid phase of mitochondrial biomembranes were investigated before and after γ-irradiation. It was revealed that K + -conductivity of the artificial phospholipid membranes (APM) formed of the phospholipids from irradiated mitochondria was substantially lower than that in the control. Using thin-layer chromatography the minor phospholipid fraction which increases K + -conductivity of APM was isolated from the lipids of unirradiated mitochondria. In the lipid preparations of irradiated mitochondria the minor phospholipid fraction content is sharply lowered (or absent at all). Besides the content of lysoforms of phosphatidylcholine and phosphatidylethanolamine as well as that of fatty acids and cholesterol esters were reduced 24 hours after irradiation. Three compounds with different capability to increase the APM conductivity for monovalent ions were revealed in the composition of the minor fraction. One of these components was shown to be lysopolyglycerophosphatide (lysodiphosphatidylglycerol). The role of the enzyme systems involved in radiational changes of the membrane lipid components and the importance of these phenomena for cell radiosensitivity will be discussed

  3. Quadrupole transport experiment with space charge dominated cesium ion beam

    International Nuclear Information System (INIS)

    Faltens, A.; Keefe, D.; Kim, C.; Rosenblum, S.; Tiefenback, M.; Warwick, A.

    1984-08-01

    The purpose of the experiment is to investigate the beam current transport limit in a long quadrupole-focussed transport channel in the space charge dominated region where the space charge defocussing force is almost as large as the average focussing force of the channel

  4. Endocrine regulation of ion transport in the avian lower intestine

    DEFF Research Database (Denmark)

    Laverty, Gary; Elbrønd, Vibeke Sødring; Árnason, Sighvatur S.

    2006-01-01

    The lower intestine (colon and coprodeum) of the domestic fowl maintains a very active, transporting epithelium, with a microvillus brush border, columnar epithelial cells, and a variety of transport systems. The colon of normal or high salt-acclimated hens expresses sodium-linked glucose and amino...

  5. Additional transport channel of carbon ions for biological research at the Nuclotron of JINR

    International Nuclear Information System (INIS)

    Yudin, I.P.; Panasik, V.A.; Tyutyunnikov, S.I.

    2011-01-01

    The paper deals with the construction of the 12 C +6 beam transport line for biomedical research at the Nuclotron accelerator complex, JINR. We have studied the scheme and modes of magneto-optical elements of the channel. The results of calculations of the investigated beam transport of carbon ions are presented. The algorithms to control the carbon ion beam in the transportation system are discussed. The choice of the magneto-optical system is motivated. The graphs of the beam envelopes in the channel are given. The scanning control beam functions are considered

  6. Additional transport channel of carbon ions for biological research at the Nuclotron of JINR

    International Nuclear Information System (INIS)

    Yudin, I.P.; Panasik, V.A.; Tyutyunnikov, S.I.

    2012-01-01

    The paper deals with the construction of the beam 12 C +6 transport line for biomedical research at the Nuclotron accelerator complex, JINR. We have studied the scheme and modes of magneto-optical elements of the channel. The results of calculations of the investigated beam transport of carbon ions are presented. The algorithms to control the carbon ion beam in the transportation system are discussed. The choice of the magneto-optical system is motivated. The graphs of the beam envelopes in the channel are given. The scanning control beam functions are considered

  7. Considerations from the viewpoint of neoclassical transport towards higher ion temperature heliotron plasmas

    International Nuclear Information System (INIS)

    Yokoyama, M.; Matsuoka, S.; Funaba, H.; Ida, K.; Nagaoka, K.; Yoshinuma, M.; Takeiri, Y.; Kaneko, O.

    2010-01-01

    The neoclassical (NC) transport analyses have been performed to elucidate the plausible approaches towards higher ion-temperature heliotron plasmas. Avoidance of the ripple transport is the key issue, for which the neoclassical ambipolar radial electric field (E r ) can be utilized. The ion-root scenario and the electron-root scenario are expected to be effective according to the experimental situation (especially, the temperature ratio between ions and electrons). The impact of the ion mass on the neoclassical ambipolar E r is also investigated to reveal the easier realization of electron-root E r in heavier ion plasmas. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Selective transport of metal ions through cation exchange membrane in the presence of a complexing agent

    Energy Technology Data Exchange (ETDEWEB)

    Tingchia Huang; Jaukai Wang (National Cheng Kung Univ., Tainan (Taiwan, Province of China))

    1993-01-01

    Selective transport of metal ions through a cation exchange membrane was studied in stirred batch dialyzer for the systems Ni[sup 2+]-Cu[sup 2+] and Cu[sup 2+]-Fe[sup 3+]. Oxalic acid, malonic acid, citric acid, glycine, and ethylenediaminetetraacetic acid were employed as the complexing agents added in the feed solution in order to increase the permselectivity of metal ions. The experimental results show that the selective transport behavior of metal ions depends on the valence and the concentration of metal ions, the stoichiometric ratio of complexing agent to metal ions, and the pH value of the feed solution, but is independent of the concentration of counterion in the stripping phase. A theoretical approach was formulated on the basis of the Nernst-Planck equation and interface quasi-equilibrium. Theoretical solutions obtained from numerical calculation were in agreement with the experimental data.

  9. Fast-ion transport and neutral beam current drive in ASDEX upgrade

    DEFF Research Database (Denmark)

    Geiger, B.; Weiland, M.; Jacobsen, Asger Schou

    2015-01-01

    The neutral beam current drive efficiency has been investigated in the ASDEX Upgrade tokamak by replacing on-axis neutral beams with tangential off-axis beams. A clear modification of the radial fast-ion profiles is observed with a fast-ion D-alpha diagnostic that measures centrally peaked profiles...... during on-axis injection and outwards shifted profiles during off-axis injection. Due to this change of the fast-ion population, a clear modification of the plasma current profile is predicted but not observed by a motional Stark effect diagnostic. The fast-ion transport caused by MHD activity has been...

  10. Literature study of volatile radioiodine release from ion-exchange resins during transportation

    International Nuclear Information System (INIS)

    Wren, J.C.

    1991-02-01

    A transport package is currently being developed by Ontario Hydro to carry used filters and ion-exchange columns from the Pickering and Darlington Nuclear Generating Stations to the Bruce Nuclear Generating Station for disposal. The main reason that the transport package must be licensed is the possibility that volatile radionuclides being transported in the package might be released during transport accidents. Of particular concern is the iodine that might become volatile due to the degradation of the ion exchange resin. This report reviews the literature on the thermal and radiolytic degradation of ion exchange resins and provides calculations to estimate the fraction of volatile iodine as a function of time under postulated accident conditions

  11. Carbonate and Bicarbonate Ion Transport in Alkaline Anion Exchange Membranes

    Science.gov (United States)

    2013-06-25

    comparable assumptions, a similar equation can be derived starting with the Nernst -Planck equation . σ = ∑ σi = ∑ F2z2i RT (ε− ε0)q D0i 1 + δi Ci [1] Using Eq...an appropriate ion-membrane diffusion coefficient. Finally, an equation derived from the dusty fluid model can be used to calculate the ionic...Finally, an equation derived from the dusty fluid model can be used to calculate the ionic conductivity of the membrane in different counter ion forms

  12. Study of the transport phenomena in III-V materials by the Monte Carlo method: application to INAS

    International Nuclear Information System (INIS)

    Bouazza, B.; Amer, L.; Guen-Bouazza, A.; Sayeh, C.; Chabanne-Sari, N.E.; Gontrand, C.

    2004-01-01

    Full text.The microelectronic comprehension of the phenomena which describes the behavior of the carriers in semiconductor materials requires the knowledge of energy distribution function. This distribution function is obtained by the resolution of Boltzmann equation which is very hard to solve analytically. Other methods based on modeling are actually successfully used to solve this equation. This Monte Carlo method is among of the most methods used for studying electronics components operations. It consists to follow the evolution of electron packets in real space, where each electron subjected to the electric field present in material goes interact with the crystal lattice. It is therefore an iterative process made up from a whole coasting flights stopped by acoustics interactions, polar and non polar optics, piezoelectric, inter-valley, impurity, ionization and surface. By applying this method to the III-V material: InAs. We can describe the behavior of the carriers from dynamic and energetic point of view (variation speed according to the field). The simulation is applied, taking into account variation of the carriers according to time in the non stationary mode, and the effect of temperature, and measurements doping. Results obtained are shown to be comparable to those of the theory

  13. A CFD analysis of transport phenomena and electrochemical reactions in a tubular-shaped PEM fuel cell

    OpenAIRE

    Maher A.R. Sadiq Al-Baghdadi

    2013-01-01

    A fuel cell is most interesting new power source because it solves not only the environment problem but also natural resource exhaustion problem. CFD modeling and simulation for heat and mass transport in PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal co...

  14. Ion current prediction model considering columnar recombination in alpha radioactivity measurement using ionized air transportation

    International Nuclear Information System (INIS)

    Naito, Susumu; Hirata, Yosuke; Izumi, Mikio; Sano, Akira; Miyamoto, Yasuaki; Aoyama, Yoshio; Yamaguchi, Hiromi

    2007-01-01

    We present a reinforced ion current prediction model in alpha radioactivity measurement using ionized air transportation. Although our previous model explained the qualitative trend of the measured ion current values, the absolute values of the theoretical curves were about two times as large as the measured values. In order to accurately predict the measured values, we reinforced our model by considering columnar recombination and turbulent diffusion, which affects columnar recombination. Our new model explained the considerable ion loss in the early stage of ion diffusion and narrowed the gap between the theoretical and measured values. The model also predicted suppression of ion loss due to columnar recombination by spraying a high-speed air flow near a contaminated surface. This suppression was experimentally investigated and confirmed. In conclusion, we quantitatively clarified the theoretical relation between alpha radioactivity and ion current in laminar flow and turbulent pipe flow. (author)

  15. Global transport and localized layering of metallic ions in the upper atmospherer

    Directory of Open Access Journals (Sweden)

    L. N. Carter

    1999-02-01

    Full Text Available A numerical model has been developed which is capable of simulating all phases of the life cycle of metallic ions, and results are described and interpreted herein for the typical case of Fe+ ions. This cycle begins with the initial deposition of metallics through meteor ablation and sputtering, followed by conversion of neutral Fe atoms to ions through photoionization and charge exchange with ambient ions. Global transport arising from daytime electric fields and poleward/ downward di.usion along geomagnetic field lines, localized transport and layer formation through de- scending convergent nulls in the thermospheric wind field, and finally annihilation by chemical neutralization and compound formation are treated. The model thus sheds new light on the interdependencies of the physical and chemical processes a.ecting atmospheric metallics. Model output analysis confirms the dominant role of both global and local transport to the ion's life cycle, showing that upward forcing from the equatorial electric field is critical to global movement, and that diurnal and semidiurnal tidal winds are responsible for the forma- tion of dense ion layers in the 90±250 km height region. It is demonstrated that the assumed combination of sources, chemical sinks, and transport mechanisms actually produces F-region densities and E-region layer densities similar to those observed. The model also shows that zonal and meridional winds and electric fields each play distinct roles in local transport, whereas the ion distribution is relatively insensitive to reasonable variations in meteoric deposition and chemical reaction rates.Key words. Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions.

  16. Global transport and localized layering of metallic ions in the upper atmospherer

    Directory of Open Access Journals (Sweden)

    L. N. Carter

    Full Text Available A numerical model has been developed which is capable of simulating all phases of the life cycle of metallic ions, and results are described and interpreted herein for the typical case of Fe+ ions. This cycle begins with the initial deposition of metallics through meteor ablation and sputtering, followed by conversion of neutral Fe atoms to ions through photoionization and charge exchange with ambient ions. Global transport arising from daytime electric fields and poleward/ downward di.usion along geomagnetic field lines, localized transport and layer formation through de- scending convergent nulls in the thermospheric wind field, and finally annihilation by chemical neutralization and compound formation are treated. The model thus sheds new light on the interdependencies of the physical and chemical processes a.ecting atmospheric metallics. Model output analysis confirms the dominant role of both global and local transport to the ion's life cycle, showing that upward forcing from the equatorial electric field is critical to global movement, and that diurnal and semidiurnal tidal winds are responsible for the forma- tion of dense ion layers in the 90±250 km height region. It is demonstrated that the assumed combination of sources, chemical sinks, and transport mechanisms actually produces F-region densities and E-region layer densities similar to those observed. The model also shows that zonal and meridional winds and electric fields each play distinct roles in local transport, whereas the ion distribution is relatively insensitive to reasonable variations in meteoric deposition and chemical reaction rates.

    Key words. Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions.

  17. Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into ring current

    Science.gov (United States)

    Cladis, J. B.; Francis, W. E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.

  18. Mechanisms involved in the transport of mercuric ions in target tissues

    Science.gov (United States)

    Bridges, Christy C.; Zalups, Rudolfs K.

    2016-01-01

    Mercury exists in the environment in various forms, all of which pose a risk to human health. Despite guidelines regulating the industrial release of mercury into the environment, humans continue to be exposed regularly to various forms of this metal via inhalation or ingestion. Following exposure, mercuric ions are taken up by and accumulate in numerous organs, including brain, intestine, kidney, liver, and placenta. In order to understand the toxicological effects of exposure to mercury, a thorough understanding of the mechanisms that facilitate entry of mercuric ions into target cells must first be obtained. A number of mechanisms for the transport of mercuric ions into target cells and organs have been proposed in recent years. However, the ability of these mechanisms to transport mercuric ions and the regulatory features of these carriers have not been characterized completely. The purpose of this review is to summarize the current findings related to the mechanisms that may be involved in the transport of inorganic and organic forms of mercury in target tissues and organs. This review will describe mechanisms known to be involved in the transport of mercury and will also propose additional mechanisms that may potentially be involved in the transport of mercuric ions into target cells. PMID:27422290

  19. Energetic and frictional effects in the transport of ions in a cyclic peptide nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Yongil; Song, Yeon Ho; Hwang, Hyeon Seok [Dept. of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon (Korea, Republic of); Schatz, George C. [Dept. of Chemistry, Northwestern University, Evanston (United States)

    2017-01-15

    The effects of geometric restraints and frictional parameters on the energetics and dynamics of ion transport through a synthetic ion channel are investigated using molecular dynamics (MD) simulations for several different ions. To do so, potential of mean force profiles and position-dependent diffusion coefficients for Na{sup +}, K{sup +}, Ca{sup 2+}, and Cl{sup −} transport through a simple cyclic peptide nanotube, which is composed of 4× cyclo[−(D-Ala-Glu-D-Ala-Gln){sub 2−}] rings, are calculated via an adaptive biasing force MD simulation method and a Baysian inference/Monte Carlo algorithm. Among the restraints and parameters examined in this work, the radius parameter used in the flat-bottom half-harmonic restraint at the entrance and exit to channel has a great effect on the energetics of ion transport through the variation of entropy in the outside of the channel. The diffusivity profiles for the ions show a strong dependence on the damping coefficient, but the dependence on the coefficient becomes minimal inside the channel, indicating that the most important factor which affects the diffusivity of ions inside the channel is local interactions of ions with the structured channel water molecules through confinement.

  20. The Structure and Transport of Water and Hydrated Ions Within Hydrophobic, Nanoscale Channels

    International Nuclear Information System (INIS)

    Holt, J.K.; Herberg, J.L.; Wu, Y.; Schwegler, E.; Mehta, A.

    2009-01-01

    The purpose of this project includes an experimental and modeling investigation into water and hydrated ion structure and transport at nanomaterials interfaces. This is a topic relevant to understanding the function of many biological systems such as aquaporins that efficiently shuttle water and ion channels that permit selective transport of specific ions across cell membranes. Carbon nanotubes (CNT) are model nanoscale, hydrophobic channels that can be functionalized, making them artificial analogs for these biological channels. This project investigates the microscopic properties of water such as water density distributions and dynamics within CNTs using Nuclear Magnetic Resonance (NMR) and the structure of hydrated ions at CNT interfaces via X-ray Absorption Spectroscopy (XAS). Another component of this work is molecular simulation, which can predict experimental measurables such as the proton relaxation times, chemical shifts, and can compute the electronic structure of CNTs. Some of the fundamental questions this work is addressing are: (1) what is the length scale below which nanoscale effects such as molecular ordering become important, (2) is there a relationship between molecular ordering and transport?, and (3) how do ions interact with CNT interfaces? These are questions of interest to the scientific community, but they also impact the future generation of sensors, filters, and other devices that operate on the nanometer length scale. To enable some of the proposed applications of CNTs as ion filtration media and electrolytic supercapacitors, a detailed knowledge of water and ion structure at CNT interfaces is critical.

  1. A three-scale model for ionic solute transport in swelling clays incorporating ion-ion correlation effects

    Science.gov (United States)

    Le, Tien Dung; Moyne, Christian; Murad, Marcio A.

    2015-01-01

    A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson-Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi's effective principle. At the macroscale, the electro-chemical-mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of

  2. Helium Bubbles Cavitation Phenomena in Pb-15.7Li and Potential Impact on Tritium Transport Behaviour in HCLL Breeding Channels

    International Nuclear Information System (INIS)

    Sedano, L. A.

    2007-01-01

    COMPU task is devoted to develop a Process Flow Diagram (PFD) modelling tool for DEMO tritium cycle for HCLL and HCPB blanket lines for DEMO. At the actual stage of definition of HCLL blanket design line this global objective requires to progress specifically on the physical reliability of tritium transport assessments at blanket design level. A rough reliability assessment with the identify cation of physical phenomena determining permeation rates into the coolant was tentatively advanced in COMPU Task Deliverable 1. In HCLL design, the tritium diffusion in the alloy under the flow conditions and radiation effects in Pb15.7Li can be theoretically justifies ed as the rate limiting processes for tritium transfer into the coolant. This Deliverable 2 focuses on the analysis of a specific radiation effect: the potential role of helium bubbles in Pb15.7Li, the discussion of its implications on tritium assessment for HCLL design and consequently the analysis of its quantitative impact (as cycle input) on HCLL PFD tritium cycle design. Thus, the contents of this report investigate: (1) the rationality of the consideration on HCLL design of helium bubble cavitation phenomena in irradiated Pb15.7Li channels on the base of fundamental analysis (He solution states in Pb15.7Li) from empirical clues provided by Pb15.7Li irradiation tests, (2) a preliminary rough He-bubble cavitation design assessment and bases for a more precise FEM calculation for helium bubble cavitation phenomena in HCLL blanket channels, (3) the analysis of direct experimental data and numerical developments needed for a precise cavitation assessment and (4) a proposal of the lay-out and general specifications of an integral proof-of-principle Cavitation Experiment (Cevitex) of Helium in Pb15.7Li. (Author) 40 refs

  3. Helium Bubbles Cavitation Phenomena in Pb-15.7Li and Potential Impact on Tritium Transport Behaviour in HCLL Breeding Channels

    Energy Technology Data Exchange (ETDEWEB)

    Sedano, L. A.

    2007-09-27

    COMPU task is devoted to develop a Process Flow Diagram (PFD) modelling tool for DEMO tritium cycle for HCLL and HCPB blanket lines for DEMO. At the actual stage of definition of HCLL blanket design line this global objective requires to progress specifically on the physical reliability of tritium transport assessments at blanket design level. A rough reliability assessment with the identify cation of physical phenomena determining permeation rates into the coolant was tentatively advanced in COMPU Task Deliverable 1. In HCLL design, the tritium diffusion in the alloy under the flow conditions and radiation effects in Pb15.7Li can be theoretically justifies ed as the rate limiting processes for tritium transfer into the coolant. This Deliverable 2 focuses on the analysis of a specific radiation effect: the potential role of helium bubbles in Pb15.7Li, the discussion of its implications on tritium assessment for HCLL design and consequently the analysis of its quantitative impact (as cycle input) on HCLL PFD tritium cycle design. Thus, the contents of this report investigate: (1) the rationality of the consideration on HCLL design of helium bubble cavitation phenomena in irradiated Pb15.7Li channels on the base of fundamental analysis (He solution states in Pb15.7Li) from empirical clues provided by Pb15.7Li irradiation tests, (2) a preliminary rough He-bubble cavitation design assessment and bases for a more precise FEM calculation for helium bubble cavitation phenomena in HCLL blanket channels, (3) the analysis of direct experimental data and numerical developments needed for a precise cavitation assessment and (4) a proposal of the lay-out and general specifications of an integral proof-of-principle Cavitation Experiment (Cevitex) of Helium in Pb15.7Li. (Author) 40 refs.

  4. Finite element computation of multi-physical micropolar transport phenomena from an inclined moving plate in porous media

    Science.gov (United States)

    Shamshuddin, MD.; Anwar Bég, O.; Sunder Ram, M.; Kadir, A.

    2018-02-01

    Non-Newtonian flows arise in numerous industrial transport processes including materials fabrication systems. Micropolar theory offers an excellent mechanism for exploring the fluid dynamics of new non-Newtonian materials which possess internal microstructure. Magnetic fields may also be used for controlling electrically-conducting polymeric flows. To explore numerical simulation of transport in rheological materials processing, in the current paper, a finite element computational solution is presented for magnetohydrodynamic, incompressible, dissipative, radiative and chemically-reacting micropolar fluid flow, heat and mass transfer adjacent to an inclined porous plate embedded in a saturated homogenous porous medium. Heat generation/absorption effects are included. Rosseland's diffusion approximation is used to describe the radiative heat flux in the energy equation. A Darcy model is employed to simulate drag effects in the porous medium. The governing transport equations are rendered into non-dimensional form under the assumption of low Reynolds number and also low magnetic Reynolds number. Using a Galerkin formulation with a weighted residual scheme, finite element solutions are presented to the boundary value problem. The influence of plate inclination, Eringen coupling number, radiation-conduction number, heat absorption/generation parameter, chemical reaction parameter, plate moving velocity parameter, magnetic parameter, thermal Grashof number, species (solutal) Grashof number, permeability parameter, Eckert number on linear velocity, micro-rotation, temperature and concentration profiles. Furthermore, the influence of selected thermo-physical parameters on friction factor, surface heat transfer and mass transfer rate is also tabulated. The finite element solutions are verified with solutions from several limiting cases in the literature. Interesting features in the flow are identified and interpreted.

  5. Switching Phenomena

    Science.gov (United States)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Mazza, M. G.; Kumar, P.; Plerou, V.; Preis, T.; Stokely, K.; Xu, L.

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines can suddenly "switch" from one behavior to another, even though they possess no perfect metronome in time. As if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many temporal patterns in physics, economics, and medicine and even begin to characterize the switching phenomena that enable a system to pass from one state to another. We discuss some applications of correlated randomness to understanding switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water's anomalies are related to a switching point (which is not unlike the "tipping point" immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not "outliers" (another Gladwell immortalization).

  6. Quantifying Ion Transport in Polymers Using Electrochemical Quartz Crystal Microbalance with Dissipation

    Science.gov (United States)

    Lutkenhaus, Jodie; Wang, Shaoyang

    For polymers in energy systems, one of the most common means of quantifying ion transport is that of electrochemical impedance spectroscopy, in which an alternating electric field is applied and the resultant impedance response is recorded. While useful, this approach misses subtle details in transient film swelling, effects of hydration or solvent shells around the transporting ion, and changes in mechanical properties of the polymer. Here we present electrochemical quartz crystal microbalance with dissipation (EQCMD) monitoring as a means to quantify ion transport, dynamic swelling, and mechanical properties of polymers during electrochemical interrogation. We focus upon EQCMD characterization of the redox-active nitroxide radical polymer, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA). Upon oxidation, PTMA becomes positively charged, which requires the transport of a complementary anion into the polymer for electroneutrality. By EQCMD, we quantify anion transport and resultant swelling upon oxidation, as well as decoupling of contributions attributed to the ion and the solvent. We explore the effect of different lithium electrolyte salts in which each salt gives different charge storage and mass transport behavior. This is attributed to varied polymer-dopant and dopant-solvent interactions. The work was supported by the Grant DE-SC0014006 funded by the U.S. Department of Energy, Office of Science.

  7. Modeling of the Ionic Multi-Species Transport Phenomena in Electrokinetic Processes and Comparison with Experimental Results

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

    2010-01-01

    A model to predict the transport of ionic species within the pore solution of porous materials, under the effect of an external electric field has been developed. A Finite Elements method was implemented and used for the integration of the Nernst-Plank equations for each ionic species considered....... Electrical neutrality was continuously assured in the model by the inclusion of the Poisson-Boltzmann equation to the system of governing equations. Voltage differences were applied across the sample as boundary conditions in order to evaluate the competition between diffusion and electromigration terms...

  8. Interaction between breaking/broken waves and infragravity-scale phenomena to control sediment suspension transport in the surf zone

    CSIR Research Space (South Africa)

    Smith, GG

    2002-07-30

    Full Text Available suspension was further found to be related to the onset of lower water-levels associated with infragravity wave action, which corresponded with a predominance of breaking/broken waves. These breaking/broken waves (which are induced by the low water... is transported down- wards. Nadaoka et al. (1989) have furthermore identi?ed an eddy structure whereby the surface roller is dominated by a nearly two-dimensional ?ow structure, bounded below by strongly three- dimensional obliquely descending eddies bringing...

  9. Transport description of intermediate processes in heavy ion collisions

    International Nuclear Information System (INIS)

    Ayik, S.; Shivakumar, B.; Shapira, D.

    1986-01-01

    An extension of the diffusion model is proposed in order to describe the intermediate processes and the compound nucleus formation in heavy ion collisions. The model describes the intermediate processes and fusion in terms of the formation and the evolution of a long-lived dinuclear molecular complex (DMC) and its subsequent decay by fragmentation. The colliding ions can be trapped into the pocket of the entrance channel nucleus-nucleus potential and a DMC is formed. This DMC acts as a doorway state towards formation of a completely equilibrated compound nucleus (CN). It evolves through the exchange of nucleons to different dinuclear configurations. At each stage of its evolution, there is a finite probability for direct fragmentation into outgoing channels by thermal penetration over the barrier. The doorway states that do not fragment relax into a CN configuration and are identified as the fusion yield. 8 refs

  10. Nonlinear saturation of dissipative trapped ion instability and anomalous transport

    International Nuclear Information System (INIS)

    Sugihara, Masayoshi; Ogasawara, Masatada.

    1977-04-01

    An expression for the turbulent collision frequency is derived by summing up the most dominant terms from each order in the perturbation expansion in order to obtain the nonlinear saturation level of the dissipative trapped ion instability. Numerical calculation shows that the anomalous diffusion coefficient at the saturated state is in good agreement with the result of Kadomtsev and Pogutse when the effect of the magnetic shear is taken into account. (auth.)

  11. Ion Transport in Nanostructured Block Copolymer/Ionic Liquid Membranes

    OpenAIRE

    Hoarfrost, Megan Lane

    2012-01-01

    Incorporating an ionic liquid into one block copolymer microphase provides a platform for combining the outstanding electrochemical properties of ionic liquids with a number of favorable attributes provided by block copolymers. In particular, block copolymers thermodynamically self-assemble into well-ordered nanostructures, which can be engineered to provide a durable mechanical scaffold and template the ionic liquid into continuous ion-conducting nanochannels. Understanding how the additio...

  12. Ion mobility and transport barriers in the tokamak plasmas

    International Nuclear Information System (INIS)

    Xiao, H.; Hazeltine, R.D.; Valanju, P.M.

    1993-06-01

    The character of charged particle motion in an axisymmetric toroidal system with a constant radial electric field is investigated both analytically and numerically. Ion radial mobility caused by the combined effects of the radial electric field and charge exchange is found. A simple moment argument in the banana regime matches the simulation results well. Relation of present work and high confinement (H-mode) experiment is also discussed

  13. Modeling of the anode of a liquid-feed DMFC: Inhomogeneous compression effects and two-phase transport phenomena

    Science.gov (United States)

    García-Salaberri, Pablo A.; Vera, Marcos; Iglesias, Immaculada

    2014-01-01

    An isothermal two-phase 2D/1D across-the-channel model for the anode of a liquid-feed Direct Methanol Fuel Cell (DMFC) is presented. The model takes into account the effects of the inhomogeneous assembly compression of the Gas Diffusion Layer (GDL), including the spatial variations of porosity, diffusivity, permeability, capillary pressure, and electrical conductivity. The effective anisotropic properties of the GDL are evaluated from empirical data reported in the literature corresponding to Toray carbon paper TGP-H series. Multiphase transport is modeled according to the classical theory of porous media (two-fluid model), considering the effect of non-equilibrium evaporation and condensation of methanol and water. The numerical results evidence that the hydrophobic Leverett J-function approach is physically inconsistent to describe capillary transport in the anode of a DMFC when assembly compression effects are considered. In contrast, more realistic results are obtained when GDL-specific capillary pressure curves reflecting the mixed-wettability characteristics of GDLs are taken into account. The gas coverage factor at the GDL/channel interface also exhibits a strong influence on the gas-void fraction distribution in the GDL, which in turn depends on the relative importance between the capillary resistance induced by the inhomogeneous compression, Rc(∝ ∂pc / ∂ ε) , and the capillary diffusivity, Dbarc(∝ ∂pc / ∂ s) .

  14. Cell Membrane Transport Mechanisms: Ion Channels and Electrical Properties of Cell Membranes.

    Science.gov (United States)

    Kulbacka, Julita; Choromańska, Anna; Rossowska, Joanna; Weżgowiec, Joanna; Saczko, Jolanta; Rols, Marie-Pierre

    2017-01-01

    Cellular life strongly depends on the membrane ability to precisely control exchange of solutes between the internal and external (environmental) compartments. This barrier regulates which types of solutes can enter and leave the cell. Transmembrane transport involves complex mechanisms responsible for passive and active carriage of ions and small- and medium-size molecules. Transport mechanisms existing in the biological membranes highly determine proper cellular functions and contribute to drug transport. The present chapter deals with features and electrical properties of the cell membrane and addresses the questions how the cell membrane accomplishes transport functions and how transmembrane transport can be affected. Since dysfunctions of plasma membrane transporters very often are the cause of human diseases, we also report how specific transport mechanisms can be modulated or inhibited in order to enhance the therapeutic effect.

  15. Studies of heavy ion beam transport in a magnetic quadrupole channel

    International Nuclear Information System (INIS)

    Klabunde, J.; Reiser, M.; Schonlein, A.; Spadtke, P.; Struckmeier, J.

    1983-01-01

    In connection with the West German Heavy Ion Fusion Program the first stage (six periods) of a magnetic quadrupole channel (FODO type) to study the transport of intense ion beams was built at GSI. Different ion beams can be used and the variation of the brightness of these beams (hence of the tune depression sigma/sigma /SUB o/ ) is sufficiently large that regions of theoretically predicted instabilities can be covered. The initial studies are being carried out with a high-brightness beam of 190 keV Ar+ ions and currents of a few mA. Since the pulse length is > 0.5 ms and the pressure is between 10 -6 and 10 -7 torr partial space charge neutralization occurs. Clearing electrodes can be used to remove the electrons from the beam. Results of theoretical studies, measurements of charge neutralization effects and first results of transport experiments are reported

  16. Kinetic Simulation of Fast Electron Transport with Ionization Effects and Ion Acceleration

    International Nuclear Information System (INIS)

    Robinson, A. P. L.; Bell, A. R.; Kingham, R. J.

    2005-01-01

    The generation of relativistic electrons and multi-MeV ions is central to ultra intense (> 1018Wcm-2) laser-solid interactions. The production of energetic particles by lasers has a number of potential applications ranging from Fast Ignition ICF to medicine. In terms of the relativistic (fast) electrons the areas of interest can be divided into three areas. Firstly there is the absorption of laser energy into fast electrons and MeV ions. Secondly there is the transport of fast electrons through the solid target. Finally there is a transduction stage, where the fast electron energy is imparted. This may range from being the electrostatic acceleration of ions at a plasma-vacuum interface, to the heating of a compressed core (as in Fast Ignitor ICF).We have used kinetic simulation codes to study the transport stage and electrostatic ion acceleration. (Author)

  17. Separation of some metal ions using coupled transport supported liquid membranes

    International Nuclear Information System (INIS)

    Chaudhary, M.A.

    1993-01-01

    Liquid membrane extraction processes has become very popular due to their superiority in many ways over other separation techniques. In coupled transport membranes the metal ions can be transported across the membrane against their concentration gradient under the influence of chemical potential difference. Liquid membranes consisting of a carrier-cum-diluent, supported in microporous polymeric hydrophobic films have been studied for transport of metal ions like U(VI), Cr(VI), Be(II), V(V), Ti(IV), Zn(II), Cd(II), Hf(IV), W(VI), and Co(II). The present paper presents basic data with respect to flux and permeabilities of these metal ions across membranes based on experimental results and theoretical equations, using different carriers and diluents and provides a brief reference to possibility of such membranes for large scale applications. (author)

  18. A reduced model for ion temperature gradient turbulent transport in helical plasmas

    International Nuclear Information System (INIS)

    Nunami, M.; Watanabe, T.-H.; Sugama, H.

    2013-07-01

    A novel reduced model for ion temperature gradient (ITG) turbulent transport in helical plasmas is presented. The model enables one to predict nonlinear gyrokinetic simulation results from linear gyrokinetic analyses. It is shown from nonlinear gyrokinetic simulations of the ITG turbulence in helical plasmas that the transport coefficient can be expressed as a function of the turbulent fluctuation level and the averaged zonal flow amplitude. Then, the reduced model for the turbulent ion heat diffusivity is derived by representing the nonlinear turbulent fluctuations and zonal flow amplitude in terms of the linear growth rate of the ITG instability and the linear response of the zonal flow potentials. It is confirmed that the reduced transport model results are in good agreement with those from nonlinear gyrokinetic simulations for high ion temperature plasmas in the Large Helical Device. (author)

  19. Ion and solvent Transport in Polypyrrole: Experimental Test of Osmotic Model

    DEFF Research Database (Denmark)

    Velmurugu, Yogambigai; Skaarup, Steen

    2005-01-01

    Ion and solvent transport in the conjugated polymer actuator material, polypyrrole, doped with the immobile anion dodecyl benzene sulphonate, has been investigated by simultaneous cyclic voltammetry and Electrochemical Quartz Crystal Microbalance measurements. The purpose was to elucidate the pre...... from almost pure cation transport to ca. equal amount of anion transport; exchanging Br- for Cl- ions has only negligible effect at lower concentrations at equal osmotic pressures. Ca. 4 H2O molecules are tightly bound to each Na+ ion at concentrations ... the precise nature of the mobile species during redox cycling, and to seek confirmation for the osmotic mechanism of actuation. Three testable aspects of the model were confirmed: The number of inserted H2O molecules decreases with electrolyte concentration; at the same time the mechanism gradually changes...

  20. Transport models for relativistic heavy-ion collisions at Relativistic ...

    Indian Academy of Sciences (India)

    While the free-streaming of particles in the kinetic theory drive the system out of equi- ... For collisions at RHIC and LHC, a transport model may involve four main com- ...... Further, there are many important conceptual issues such as imple-.

  1. A Hierarchy of Transport Approximations for High Energy Heavy (HZE) Ions

    Science.gov (United States)

    Wilson, John W.; Lamkin, Stanley L.; Hamidullah, Farhat; Ganapol, Barry D.; Townsend, Lawrence W.

    1989-01-01

    The transport of high energy heavy (HZE) ions through bulk materials is studied neglecting energy dependence of the nuclear cross sections. A three term perturbation expansion appears to be adequate for most practical applications for which penetration depths are less than 30 g per sq cm of material. The differential energy flux is found for monoenergetic beams and for realistic ion beam spectral distributions. An approximate formalism is given to estimate higher-order terms.

  2. The molecular mechanism of ion-dependent gating in secondary transporters.

    Directory of Open Access Journals (Sweden)

    Chunfeng Zhao

    2013-10-01

    Full Text Available LeuT-like fold Na-dependent secondary active transporters form a large family of integral membrane proteins that transport various substrates against their concentration gradient across lipid membranes, using the free energy stored in the downhill concentration gradient of sodium ions. These transporters play an active role in synaptic transmission, the delivery of key nutrients, and the maintenance of osmotic pressure inside the cell. It is generally believed that binding of an ion and/or a substrate drives the conformational dynamics of the transporter. However, the exact mechanism for converting ion binding into useful work has yet to be established. Using a multi-dimensional path sampling (string-method followed by all-atom free energy simulations, we established the principal thermodynamic and kinetic components governing the ion-dependent conformational dynamics of a LeuT-like fold transporter, the sodium/benzyl-hydantoin symporter Mhp1, for an entire conformational cycle. We found that inward-facing and outward-facing states of Mhp1 display nearly the same free energies with an ion absent from the Na2 site conserved across the LeuT-like fold transporters. The barrier separating an apo-state from inward-facing or outward-facing states of the transporter is very low, suggesting stochastic gating in the absence of ion/substrate bound. In contrast, the binding of a Na2 ion shifts the free energy stabilizing the outward-facing state and promoting substrate binding. Our results indicate that ion binding to the Na2 site may also play a key role in the intracellular thin gate dynamics modulation by altering its interactions with the transmembrane helix 5 (TM5. The Potential of Mean Force (PMF computations for a substrate entrance displays two energy minima that correspond to the locations of the main binding site S1 and proposed allosteric S2 binding site. However, it was found that substrate's binds to the site S1 ∼5 kcal/mol more favorable

  3. P.I.A.F.E project: long distance transport of low energy exotic ions

    International Nuclear Information System (INIS)

    Nibart, V.

    1996-01-01

    The aim of the PIAFE project is the long distance (400 m) transport of a low energy radioactive ion beam from the ILL (Institut Laue Langevin) to the ISN (Institut des Sciences Nucleaires) of Grenoble (France). The production, extraction, ionization and mass separation of ions is performed by the ILL, while the transformation of ions into multicharged ions, their stripping and acceleration is carried out at the ISN. Theoretical and experimental studies for a simple an original guidance solution have shown that such a long transport, even delicate, should not encounter any major difficulty. The main objectives of this thesis is the technical realization of a 18 m section of this transport line. The problem of supports and focalizing elements alignment has been solved together with the other problems such as: the central trajectory deviation due to alignment defects and to the Earth's magnetic field; the particle losses due to charge exchange with the residual gas and the emittance increase by Coulomb scattering. It has been demonstrated that a 90% transmission can be obtained using a 25 keV energy and a 10 -7 mbar vacuum. Experimental measurements using a rubidium ion source have allowed to validate a theoretical model of emittance increase due to the residual gas-ions interactions. The increase of emittance with respect to the pressure has been measured using four residual gases of different mass. (J.S.). 29 refs., 61 figs., 19 tabs., 8 photos., 4 appends

  4. Ion beam transport and focus for LMF using an achromatic solenoidal lens system

    International Nuclear Information System (INIS)

    Olson, C.L.

    1990-01-01

    The light ion LMF (Laboratory Microfusion Facility) requires an ion beam transport length for bunching and standoff to be about four meters from the diode to the target. The baseline LMF transport scheme uses an achromatic two lens system consisting of the diode (a self-field lens) and a solenoidal lens. Charge and current neutralization are provided by a background gas. A detailed analysis of this system is presented here. The effects of additional magnetic fields are examined, including those produced by non-zero net currents, applied B effects near the diode, and diamagnetic effects in the solenoidal lens. Instabilities are analyzed including the filamentation instability, the two-stream instability (beam ions, plasma electrons), the plasma two-stream instability (plasma electrons, plasma ions), and the ion acoustic instability. Scattering in the foil and gas are shown to be negligible. Gas breakdown processes are analyzed in detail, including ion impact ionization, electron avalanching, and ohmic heating. Special diode requirements are examined, including voltage accuracy, energy spread, and aiming tolerances. The neutral gas and gas pressure are chosen to satisfy several constraints, one being that the net current must be small, and another being that the filamentation instability should be avoided. With the present choice of 1 Torr He, it is concluded that the complete achromatic lens system appears to be viable, simple, and efficient transport and focusing system for LMF

  5. Ion thermal conductivity and convective energy transport in JET hot-ion regimes and H-modes

    International Nuclear Information System (INIS)

    Tibone, F.; Balet, B.; Cordey, J.G.

    1989-01-01

    Local transport in a recent series of JET experiments has been studied using interpretive codes. Auxiliary heating, mainly via neutral beam injection, was applied on low-density target plasmas confined in the double-null X-point configuration. This has produced two-component plasmas with high ion temperature and neutron yield and, above a threshold density, H-modes characterised by peak density and power deposition profiles. H-mode confinement was also obtained for the first time with 25 MW auxiliary power, of which 10 MW was from ion cyclotron resonance heating. We have used profile measurements of electron temperature T e from electron cyclotron emission and LIDAR Thomson scattering, ion temperature T i from charge-exchange recombination spectroscopy (during NBI), electron density n e from LIDAR and Abel-inverted interferometer measurements. Only sparse information is, however, available to date concerning radial profiles of effective ionic charge and radiation losses. Deuterium depletion due to high impurity levels is an important effect in these discharges, and our interpretation of thermal ion energy content, neutron yield and ion particle fluxes needs to be confirmed using measured Z eff -profiles. (author) 4 refs., 4 figs

  6. Ion transport membrane module and vessel system with directed internal gas flow

    Science.gov (United States)

    Holmes, Michael Jerome; Ohrn, Theodore R.; Chen, Christopher Ming-Poh

    2010-02-09

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an inlet adapted to introduce gas into the interior of the vessel, an outlet adapted to withdraw gas from the interior of the vessel, and an axis; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region; and (c) one or more gas flow control partitions disposed in the interior of the pressure vessel and adapted to change a direction of gas flow within the vessel.

  7. Ion transport by gating voltage to nanopores produced via metal-assisted chemical etching method

    Science.gov (United States)

    Van Toan, Nguyen; Inomata, Naoki; Toda, Masaya; Ono, Takahito

    2018-05-01

    In this work, we report a simple and low-cost way to create nanopores that can be employed for various applications in nanofluidics. Nano sized Ag particles in the range from 1 to 20 nm are formed on a silicon substrate with a de-wetting method. Then the silicon nanopores with an approximate 15 nm average diameter and 200 μm height are successfully produced by the metal-assisted chemical etching method. In addition, electrically driven ion transport in the nanopores is demonstrated for nanofluidic applications. Ion transport through the nanopores is observed and could be controlled by an application of a gating voltage to the nanopores.

  8. Modeling of charge transport in ion bipolar junction transistors.

    Science.gov (United States)

    Volkov, Anton V; Tybrandt, Klas; Berggren, Magnus; Zozoulenko, Igor V

    2014-06-17

    Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poisson's and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.

  9. Electrical Resistance and Transport Numbers of Ion-Exchange Membranes Used in Electrodialytic Soil Remediation

    DEFF Research Database (Denmark)

    Hansen, Henrik; Ottosen, Lisbeth M.; Villumsen, Arne

    1999-01-01

    Electrodialytic soil remediation is a recently developed method to decontaminate heavy metal polluted soil using ion-exchange membranes. In this method one side of the ion-exchange membrane is in direct contact with the polluted soil. It is of great importance to know if this contact with the soil...... different electrodialytic soil remediation experiments. The experiments showed that after the use in electrodialytic soil remediation, the ion-exchange membranes had transport numbers in the same magnitude as new membranes. The electrical resistance for six membranes did not differ from that of new...

  10. Space Charge Compensation in the Linac4 Low Energy Beam Transport Line with Negative Hydrogen Ions

    CERN Document Server

    Valerio-Lizarraga, C; Leon-Monzon, I; Lettry, J; Midttun, O; Scrivens, R

    2014-01-01

    The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Tranport (LEBT) using the package IBSimu1, which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H- beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.

  11. The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films.

    Science.gov (United States)

    Gudjonsdottir, Solrun; van der Stam, Ward; Kirkwood, Nicholas; Evers, Wiel H; Houtepen, Arjan J

    2018-05-16

    Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li + and Na + the onset is at significantly less negative potentials. For larger ions (K + , quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li + and Na + . Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies.

  12. Status of the SNS H- ion source and low-energy beam transport system

    International Nuclear Information System (INIS)

    Keller, R.; Thomae, R.; Stockli, M.; Welton, R.

    2002-01-01

    The ion source and Low-Energy Transport (LEBT) system that will provide H - ion beams to the Spallation Neutron Source (SNS) Front End and the accelerator chain have been developed into a mature unit that will satisfy the operational needs through the commissioning and early operating phases of SNS. The ion source was derived from the SSC ion source, and many of its original features have been improved to achieve reliable operation at 6% duty factor, producing beam currents in the 35-mA range and above. The LEBT utilizes purely electrostatic focusing and includes static beam-steering elements and a pre-chopper. This paper will discuss the latest design features of the ion source and LEBT, give performance data for the integrated system, and report on relevant commissioning results obtained with the SNS RFQ accelerator. Perspectives for further improvements will be outlined in concluding remarks

  13. Relationship between ion transport and the failure behavior of epoxy resin coatings

    International Nuclear Information System (INIS)

    Dong, Yuhua; Zhou, Qiong

    2014-01-01

    Highlights: •An epoxy resin-Q345 system with a sandwich structure was prepared. •Cl − ions permeated into epoxy resin coating prior to K + ions. •Free volume size and PAL increased when the coating was immersed into the solution. -- Abstract: An epoxy resin coating with a sandwich structure was prepared to investigate ion transport behavior in the coating. The macro- and micro- appearance of the coating immersed in 5 wt.% KCl solutions was observed by stereomicroscopy, scanning electron microscopy equipped with an energy dispersive spectrometer. The electrochemical property of the coating was characterized by electrochemical impedance spectroscopy, and change of free volume after immersion was characterized by positron annihilation lifetime spectroscopy. The results indicated that Cl − ions permeated into the coating prior to K + ions, the free volume size and positron annihilation lifetime of the coating increased during immersion

  14. Transport of intense particle beams with application to heavy ion fusion

    International Nuclear Information System (INIS)

    Buchanan, H.L.; Chambers, F.W.; Lee, E.P.; Yu, S.S.; Briggs, R.J.; Rosenbluth, M.N.

    1979-01-01

    An attractive feature of the high energy (> GeV) heavy ion beam approach to inertial fusion, as compared with other particle beam systems, is the relative simplicity involved in the transport and focusing of energy on the target inside a reactor chamber. While this focusing could be done in vacuum by conventional methods with multiple beams, there are significant advantages in reactor design if one can operate at gas pressures around one torr. In this paper we summarize the results of our studies of heavy ion beam transport in gases. With good enough charge and current neutralization, one could get a ballistically-converging beam envelope down to a few millimeters over a 10 meter path inside the chamber. Problems of beam filamentation place important restrictions on this approach. We also discuss transport in a self-focused mode, where a relatively stable pressure window is predicted similar to the observed window for electron beam transport

  15. Impact of beam transport method on chamber and driver design for heavy ion inertial fusion energy

    Energy Technology Data Exchange (ETDEWEB)

    Rose, D.V.; Welch, D.R.; Olson, C.L.; Yu, S.S.; Neff, S.; Sharp, W.M.

    2002-12-01

    In heavy ion inertial fusion energy systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. In this paper, we examine three different modes of beam propagation: neutralized ballistic transport, assisted pinched transport, and self-pinched transport. The status of our understanding of these three modes is summarized, and the constraints imposed by beam propagation upon the chamber environment, as well as their compatibility with various chamber and target concepts, are considered. We conclude that, on the basis of our present understanding, there is a reasonable range of parameter space where beams can propagate in thick-liquid wall, wetted-wall, and dry-wall chambers.

  16. Role of Dielectric Constant on Ion Transport: Reformulated Arrhenius Equation

    Directory of Open Access Journals (Sweden)

    Shujahadeen B. Aziz

    2016-01-01

    Full Text Available Solid and nanocomposite polymer electrolytes based on chitosan have been prepared by solution cast technique. The XRD results reveal the occurrence of complexation between chitosan (CS and the LiTf salt. The deconvolution of the diffractogram of nanocomposite solid polymer electrolytes demonstrates the increase of amorphous domain with increasing alumina content up to 4 wt.%. Further incorporation of alumina nanoparticles (6 to 10 wt.% Al2O3 results in crystallinity increase (large crystallite size. The morphological (SEM and EDX analysis well supported the XRD results. Similar trends of DC conductivity and dielectric constant with Al2O3 concentration were explained. The TEM images were used to explain the phenomena of space charge and blocking effects. The reformulated Arrhenius equation (σ(ε′,T=σoexp(-Ea/KBε′T was proposed from the smooth exponential behavior of DC conductivity versus dielectric constant at different temperatures. The more linear behavior of DC conductivity versus 1000/(ɛ′×T reveals the crucial role of dielectric constant in Arrhenius equation. The drawbacks of Arrhenius equation can be understood from the less linear behavior of DC conductivity versus 1000/T. The relaxation processes have been interpreted in terms of Argand plots.

  17. Heavy ion beam transport through liquid lithium first wall ICF reactor cavities

    International Nuclear Information System (INIS)

    Stroud, P.D.

    1985-01-01

    This analysis addresses the critical issue of the final transport of a heavy ion beam in an inertial confinement fusion reactor. The beam must traverse the reaction chamber from the final focusing lens to the target without being disrupted. This requirement has a strong impact on the reactor design. It is essential to the development of ICF fusion reactor technology, that the restrictions placed on the reactor engineering parameters by final beam transport consideration be understood early on

  18. Ion Transport and Structure in Polymer Electrolytes with Applications in Lithium Batteries

    Science.gov (United States)

    Chintapalli, Mahati

    When mixed with lithium salts, polymers that contain more than one chemical group, such as block copolymers and endgroup-functionalized polymers, are promising electrolyte materials for next-generation lithium batteries. One chemical group can provide good ion solvation and transport properties, while the other chemical group can provide secondary properties that improve the performance characteristics of the battery. Secondary properties of interest include non-flammability for safer lithium ion batteries and high mechanical modulus for dendrite resistance in high energy density lithium metal batteries. Block copolymers and other materials with multiple chemical groups tend to exhibit nanoscale heterogeneity and can undergo microphase separation, which impacts the ion transport properties. In block copolymers that microphase separate, ordered self-assembled structures occur on longer length scales. Understanding the interplay between structure at different length scales, salt concentration, and ion transport is important for improving the performance of multifunctional polymer electrolytes. In this dissertation, two electrolyte materials are characterized: mixtures of endgroup-functionalized, short chain perfluoropolyethers (PFPEs) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt, and mixtures of polystyrene-block-poly(ethylene oxide) (PS- b-PEO; SEO) and LiTFSI. The PFPE/LiTFSI electrolytes are liquids in which the PFPE backbone provides non-flammability, and the endgroups resemble small molecules that solvate ions. In these electrolytes, the ion transport properties and nanoscale heterogeneity (length scale 1 nm) are characterized as a function of endgroup using electrochemical techniques, nuclear magnetic resonance spectroscopy, and wide angle X-ray scattering. Endgroups, especially those containing PEO segments, have a large impact on ionic conductivity, in part because the salt distribution is not homogenous; we find that salt partitions

  19. Fast-ion transport studies using FIDA spectroscopy at the ASDEX Upgrade tokamak

    International Nuclear Information System (INIS)

    Geiger, Benedikt

    2013-01-01

    A good confinement of fast-ions, i.e. ions with energies above the thermal energy, is essential for the success of fusion devices as it determines, amongst others, the plasma performance and the heating and current drive efficiencies. In case of a turbulent or magneto-hydrodynamic (MHD) active background plasma, various mechanisms have to be considered in order to estimate the spatial distribution of the fast-ions: the slowing down and radial diffusion by Coulomb collisions on electrons and ions, the effect of potential fluctuations and the effect of perturbations of the magnetic field structure. These can lead to a broadening of the fast-ion distribution function which is not yet completely understood. At the fusion experiment ASDEX Upgrade, the fast-ions are generated by heating sources such as neutral beam injection (NBI). Their transport properties can be studied by a fast-ion D-alpha (FIDA) spectroscopy diagnostic which has been built in the framework of this thesis. Through charge exchange reactions with neutrals, fast-ions can receive a bound electron and emit Balmer alpha line radiation. This so-called FIDA radiation can be measured with large Doppler shifts and is localized along the NBI path where a high density of neutrals is present. The FIDA diagnostic uses radially distributed lines of sight that intersect, in the horizontal and in the vertical plane, the path of a 2.5 MW NBI heating source. Thereby different parts of the fast-ion phase space above 25 keV can be analyzed. To interpret the FIDA radiation quantitatively, a forward modelling code has been implemented, tested and further developed. The code calculates, based on theoretical fast-ion distribution functions, synthetic FIDA spectra that can be compared to the measurement. In MHD-quiescent plasmas, the possible effect of turbulence on the fast-ion transport has been investigated with the FIDA diagnostic. The measurements obtained under different experimental conditions, such as during on- and

  20. Polystyrene nanoparticles activate ion transport in human airway epithelial cells

    Directory of Open Access Journals (Sweden)

    McCarthy J

    2011-06-01

    Full Text Available J McCarthy1, X Gong2, D Nahirney2, M Duszyk2, MW Radomski11School of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Trinity College Dublin, Dublin, Ireland; 2Department of Physiology, University of Alberta, Edmonton, Alberta, CanadaBackground: Over the last decade, nanotechnology has provided researchers with new nanometer materials, such as nanoparticles, which have the potential to provide new therapies for many lung diseases. In this study, we investigated the acute effects of polystyrene nanoparticles on epithelial ion channel function.Methods: Human submucosal Calu-3 cells that express cystic fibrosis transmembrane conductance regulator (CFTR and baby hamster kidney cells engineered to express the wild-type CFTR gene were used to investigate the actions of negatively charged 20 nm polystyrene nanoparticles on short-circuit current in Calu-3 cells by Ussing chamber and single CFTR Cl- channels alone and in the presence of known CFTR channel activators by using baby hamster kidney cell patches.Results: Polystyrene nanoparticles caused sustained, repeatable, and concentration-dependent increases in short-circuit current. In turn, these short-circuit current responses were found to be biphasic in nature, ie, an initial peak followed by a plateau. EC50 values for peak and plateau short-circuit current responses were 1457 and 315.5 ng/mL, respectively. Short-circuit current was inhibited by diphenylamine-2-carboxylate, a CFTR Cl- channel blocker. Polystyrene nanoparticles activated basolateral K+ channels and affected Cl- and HCO3- secretion. The mechanism of short-circuit current activation by polystyrene nanoparticles was found to be largely dependent on calcium-dependent and cyclic nucleotide-dependent phosphorylation of CFTR Cl- channels. Recordings from isolated inside-out patches using baby hamster kidney cells confirmed the direct activation of CFTR Cl- channels by the nanoparticles.Conclusion: This is the first study to identify

  1. Angular neutron transport investigation in the HZETRN free-space ion and nucleon transport and shielding computer program

    International Nuclear Information System (INIS)

    Singleterry, R.C. Jr.; Wilson, J.W.

    1997-01-01

    Extension of the high charge and energy (HZE) transport computer program HZETRN for angular transport of neutrons is considered. For this paper, only light ion transport, He 4 and lighter, will be analyzed using a pure solar proton source. The angular transport calculator is the ANISN/PC program which is being controlled by the HZETRN program. The neutron flux values are compared for straight-ahead transport and angular transport in one dimension. The shield material is aluminum and the target material is water. The thickness of these materials is varied; however, only the largest model calculated is reported which is 50 gm/cm 2 of aluminum and 100 gm/cm 2 of water. The flux from the ANISN/PC calculation is about two orders of magnitude lower than the flux from HZETRN for very low energy neutrons. It is only a magnitude lower for the neutrons in the 10 to 20 MeV range in the aluminum and two orders lower in the water. The major reason for this difference is in the transport modes: straight-ahead versus angular. The angular treatment allows a longer path length than the straight-ahead approximation. Another reason is the different cross section sets used by the ANISN/PC-BUGLE-80 mode and the HZETRN mode. The next step is to investigate further the differences between the two codes and isolate the differences to just the angular versus straight-ahead transport mode. Then, create a better coupling between the angular neutron transport and the charged particle transport

  2. Energetic-particle-driven instabilities and induced fast-ion transport in a reversed field pinch

    International Nuclear Information System (INIS)

    Lin, L.; Brower, D. L.; Ding, W. X.; Anderson, J. K.; Capecchi, W.; Eilerman, S.; Forest, C. B.; Koliner, J. J.; Nornberg, M. D.; Reusch, J.; Sarff, J. S.; Liu, D.

    2014-01-01

    Multiple bursty energetic-particle (EP) driven modes with fishbone-like structure are observed during 1 MW tangential neutral-beam injection in a reversed field pinch (RFP) device. The distinguishing features of the RFP, including large magnetic shear (tending to add stability) and weak toroidal magnetic field (leading to stronger drive), provide a complementary environment to tokamak and stellarator configurations for exploring basic understanding of EP instabilities. Detailed measurements of the EP mode characteristics and temporal-spatial dynamics reveal their influence on fast ion transport. Density fluctuations exhibit a dynamically evolving, inboard-outboard asymmetric spatial structure that peaks in the core where fast ions reside. The measured mode frequencies are close to the computed shear Alfvén frequency, a feature consistent with continuum modes destabilized by strong drive. The frequency pattern of the dominant mode depends on the fast-ion species. Multiple frequencies occur with deuterium fast ions compared to single frequency for hydrogen fast ions. Furthermore, as the safety factor (q) decreases, the toroidal mode number of the dominant EP mode transits from n=5 to n=6 while retaining the same poloidal mode number m=1. The transition occurs when the m=1, n=5 wave-particle resonance condition cannot be satisfied as the fast-ion safety factor (q fi ) decreases. The fast-ion temporal dynamics, measured by a neutral particle analyzer, resemble a classical predator-prey relaxation oscillation. It contains a slow-growth phase arising from the beam fueling followed by a rapid drop when the EP modes peak, indicating that the fluctuation-induced transport maintains a stiff fast-ion density profile. The inferred transport rate is strongly enhanced with the onset of multiple EP modes

  3. Ion transport under the effect of an electric field in porous medium: application to the separation of rare earths by focalization electrophoresis

    International Nuclear Information System (INIS)

    Vieira-Nunes, A.I.

    1999-01-01

    Trivalent ions of rare earth elements have very similar properties and their difficult separation each from another is usually carried out by liquid-liquid extraction or ion exchange. Focalization electrophoresis represents an alternative route to the usual techniques. The purpose of this work consisted of the fundamental investigation of ion transport phenomena in electrophoretic processes. Focalization electrophoresis is suitable for separation of amphoteric species such as rare earth ions, using a pH gradient in the cell and upon addition of a complexed agent e. g. EDTA. This technique relies upon the difference in iso-electrical points of the considered species, being under the form of free cation near the anode, and in the form of anionic complexed species closer to the cathode. Rare earth species are submitted to the antagonist effects of diffusion and migration, enabling their focalization to occur at the iso-electrical point, corresponding to nil value of their effective mobility. Following a literature survey on rare earth elements and electrophoresis processes, the document describes theoretical and experimental investigations of complexation equilibria of some rare earth elements, namely lanthanum, neodymium, praseodymium and cerium, depending on pH. Values for the iso-electrical points could be estimated. Transport and focalization phenomena in view of rare earth separation, are dealt in the last chapter. Investigations were first carried out without forced circulation of the electrolyte solution and the transient behavior of the system allowed operating conditions to be design and built-up of a continuous device, more suitable to separation, and provided with 42 potential and 42 temperature sensors: the results of the preliminary runs, in form of variable profiles, are presented and discussed. (author)

  4. Simulation study of wave phenomena from the sheath region in single frequency capacitively coupled plasma discharges; field reversals and ion reflection

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, S.; Turner, M. M. [National Centre for Plasma Science and Technology, School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

    2013-07-15

    Capacitively coupled radio-frequency (RF) discharges have great significance for industrial applications. Collisionless electron heating in such discharges is important, and sometimes is the dominant mechanism. This heating is usually understood to originate in a stochastic interaction between electrons and the electric fields. However, other mechanisms may also be important. There is evidence of wave emission with a frequency near the electron plasma frequency, i.e., ω{sub pe}, from the sheath region in collisionless capacitive RF discharges. This is the result of a progressive breakdown of quasi-neutrality close to the electron sheath edge. These waves are damped in a few centimeters during their propagation from the sheath towards the bulk plasma. The damping occurs because of the Landau damping or some related mechanism. This research work reports that the emission of waves is associated with a field reversal during the expanding phase of the sheath. Trapping of electrons near to this field reversal region is observed. The amplitude of the wave increases with increasing RF current density amplitude J(tilde sign){sub 0} until some maximum is reached, beyond which the wave diminishes and a new regime appears. In this new regime, the density of the bulk plasma suddenly increases because of ion reflection, which occurs due to the presence of strong field reversal near sheath region. Our calculation shows that these waves are electron plasma waves. These phenomena occur under extreme conditions (i.e., higher J(tilde sign){sub 0} than in typical experiments) for sinusoidal current waveforms, but similar effects may occur with non-sinusoidal pulsed waveforms for conditions of experimental interest, because the rate of change of current is a relevant parameter. The effect of electron elastic collisions on plasma waves is also investigated.

  5. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation; Phenomenes de transport couples dans les argiles du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Paszkuta, M

    2005-06-15

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  6. Ion transport properties of lithium ionic liquids and their ion gels

    International Nuclear Information System (INIS)

    Shobukawa, Hitoshi; Tokuda, Hiroyuki; Susan, Md. Abu Bin Hasan; Watanabe, Masayoshi

    2005-01-01

    A new series of lithium ionic liquids were prepared by introducing of two electron-withdrawing trifluoroacetyl groups in borate salts containing two methoxy-oligo(ethylene oxide) groups in the structures. Successive substitution reactions of oligo-ethylene glycol monomethyl ether and trifluroacetic acid from LiBH 4 yielded the lithium salts, which were clear and colorless liquids at room temperature. The fundamental physicochemical properties, such as density, thermal property, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability, were measured. The lithium ionic liquids had self-dissociation ability and conducted ions even in the absence of organic solvents. New polymer electrolytes, named 'ion gels', were prepared by radical cross-linking reactions of a poly(ethylene oxide-co-propylene oxide)tri-acrylate macromonomer in the presence the lithium ionic liquid. An increase in the glass transition temperatures (T g ) of the ion gels was very small even with increasing lithium ionic liquid concentration, and the T g 's were lower than that of the ionic liquid itself. The ionic conductivity of the ion gels surpassed that of the lithium ionic liquid in the bulk at certain compositions

  7. Simulation study of energetic ion transport due to Alfven eigenmodes in LHD plasma

    International Nuclear Information System (INIS)

    Todo, Yasushi; Nakajima, Noriyoshi; Osakabe, Masaki; Yamamoto, Satoshi; Spong, Donald A.

    2008-01-01

    The creation of holes and clumps in an energetic ion energy spectrum associated with Alfven eigenmodes was examined using the neutral particle analyzer (NPA) on the LHD shot no.47645. The difference in slowing-down times between the holes and clumps suggested that the energetic ions were transported over 10% of the plasma minor radius. The spatial profile and frequency of the Alfven eigenmodes were analyzed with the AE3D code. The phase space structures of the energetic ions on the NPA line-of-sight were investigated with Poincare plots, where an oscillating Alfven eigenmode was employed for earth plot. The phase space regions trapped by the Alfven eigenmodes appeared as islands in the Poincare plots. The radial width of the islands corresponded to the transport distance of the energetic ions. Since island width depends on Alfven eigenmode amplitude, it was found that Alfven eigenmodes with amplitude δB r /B - 10 -3 transported energetic ions over 10% of the minor radius. (author)

  8. Transport theory for deeply inelastic heavy-ion collisions within the statistical model

    International Nuclear Information System (INIS)

    Shlomo, S.

    1978-01-01

    The theory I am going to describe has been developed recently by Agassi, Ko and Weidenmueller. It is based on a random-matrix model for the form factor (FF) which couples a collective degree of freedom, taken to be the distance anti r between the two ions, with the intrinsic degrees of freedom. This study of dissipative phenomena in a microsystem was triggered by the success of the simple friction and diffusion models in describing experimental data on deeply inelastic collisions. I plan to describe the underlying physical assumptions, to outline the theoretical developments and to show some very recent results. (orig.) [de

  9. The influence of collisional and anomalous radial diffusion on parallel ion transport in edge plasmas

    International Nuclear Information System (INIS)

    Helander, P.; Hazeltine, R.D.; Catto, P.J.

    1996-01-01

    The orderings in the kinetic equations commonly used to study the plasma core of a tokamak do not allow a balance between parallel ion streaming and radial diffusion, and are, therefore, inappropriate in the plasma edge. Different orderings are required in the edge region where radial transport across the steep gradients associated with the scrape-off layer is large enough to balance the rapid parallel flow caused by conditions close to collecting surfaces (such as the Bohm sheath condition). In the present work, we derive and solve novel kinetic equations, allowing for such a balance, and construct distinctive transport laws for impure, collisional, edge plasmas in which the perpendicular transport is (i) due to Coulomb collisions of ions with heavy impurities, or (ii) governed by anomalous diffusion driven by electrostatic turbulence. In both the collisional and anomalous radial transport cases, we find that one single diffusion coefficient determines the radial transport of particles, momentum and heat. The parallel transport laws and parallel thermal force in the scrape-off layer assume an unconventional form, in which the relative ion-impurity flow is driven by a combination of the conventional parallel gradients, and new (i) collisional or (ii) anomalous terms involving products of radial derivatives of the temperature and density with the radial shear of the parallel velocity. Thus, in the presence of anomalous radial diffusion, the parallel ion transport cannot be entirely classical, as usually assumed in numerical edge computations. The underlying physical reason is the appearance of a novel type of parallel thermal force resulting from the combined action of anomalous diffusion and radial temperature and velocity gradients. In highly sheared flows the new terms can modify impurity penetration into the core plasma

  10. Beam-transport system for high-resolution heavy-ion spectroscopy

    International Nuclear Information System (INIS)

    Roussel, P.; Kashy, E.

    1980-01-01

    A method is given to adjust a beam-transport system to the requirements of high-energy resolution heavy-ion spectroscopy. The results of a test experiment performed on a MP tandem with a 12 C beam are shown. A drastic improvement in energy resolution is obtained for a kinematical factor K=1/p dp/dtheta=0.12 [fr

  11. Multicomponent ion transport in a mono and bilayer cation-exchange membrane at high current density

    NARCIS (Netherlands)

    Moshtari Khah, S.; Oppers, N.A.W.; de Groot, M.T.; Keurentjes, J.T.F.; Schouten, J.C.; van der Schaaf, J.

    2017-01-01

    This work describes a model for bilayer cation-exchange membranes used in the chlor-alkali process. The ion transport inside the membrane is modeled with the Nernst–Planck equation. A logistic function is used at the boundary between the two layers of the bilayer membrane to describe the change in

  12. Nernst-Planck modeling of multicomponent ion transport in a Nafion membrane at high current density

    NARCIS (Netherlands)

    Moshtari Khah, S.; Oppers, N.A.W.; de Groot, M.T.; Keurentjes, J.T.F.; Schouten, J.C.; van der Schaaf, J.

    A mathematical model of multicomponent ion transport through a cation-exchange membrane is developed based on the Nernst–Planck equation. A correlation for the non-linear potential gradient is derived from current density relation with fluxes. The boundary conditions are determined with the Donnan

  13. Effect of salinity on expression of branchial ion transporters in striped bass (Morone saxatilis)

    DEFF Research Database (Denmark)

    Tipsmark, Christian Kølbaek; Madsen, Steffen Søndergaard; Borski, Russell John

    2004-01-01

    The time course of osmoregulatory adjustments and expressional changes of three key ion transporters in the gill were investigated in the striped bass during salinity acclimations. In three experiments, fish were transferred from fresh water (FW) to seawater (SW), from SW to FW, and from 15-ppt b...

  14. Electronic transport in helium-ion-beam etched encapsulated graphene nanoribbons

    NARCIS (Netherlands)

    Nanda, G.; Hlawacek, Gregor; Goswami, S.; Watanabe, Kenji; Taniguchi, Takashi; Alkemade, P.F.A.

    2017-01-01

    We report the etching of and electronic transport in nanoribbons of graphene sandwiched between atomically flat hexagonal boron nitride (h-BN). The etching of ribbons of varying width was achieved with a focused beam of 30 keV He+ ions. Using in-situ electrical measurements, we

  15. Cathode and electrolyte materials for solid oxide fuel cells and ion transport membranes

    Science.gov (United States)

    Jacobson, Allan J; Wang, Shuangyan; Kim, Gun Tae

    2014-01-28

    Novel cathode, electrolyte and oxygen separation materials are disclosed that operate at intermediate temperatures for use in solid oxide fuel cells and ion transport membranes based on oxides with perovskite related structures and an ordered arrangement of A site cations. The materials have significantly faster oxygen kinetics than in corresponding disordered perovskites.

  16. Effects of nitrogen seeding on core ion thermal transport in JET ILW L-mode plasmas

    NARCIS (Netherlands)

    Bonanomi, N.; Mantica, P.; Citrin, J.; Giroud, C.; Lerche, E.; Sozzi, C.; Taylor, D.; Tsalas, M.; Van Eester, D.; JET Contributors,

    2018-01-01

    A set of experiments was carried out in JET ILW (Joint European Torus with ITER-Like Wall) L-mode plasmas in order to study the effects of light impurities on core ion thermal transport. N was puffed into some discharges and its profile was measured by active Charge Exchange diagnostics, while ICRH

  17. Effect of acute hyperglycemia on erythrocyte membrane ion transport in offspring of hypertensive parents

    Czech Academy of Sciences Publication Activity Database

    Suchánková, G.; Vlasáková, Z.; Zicha, Josef; Vokurková, Martina; Dobešová, Zdenka; Pelikánová, T.

    2003-01-01

    Roč. 21, č. 7 (2003), s. 1325-1330 ISSN 0263-6352 R&D Projects: GA ČR GA305/00/1638; GA MZd NB6682 Institutional research plan: CEZ:AV0Z5011922 Keywords : ion transport * hypertension * insulin resistance Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 3.572, year: 2003

  18. Heavy ion inertial fusion: interface between target gain, accelerator phase space and reactor beam transport revisited

    International Nuclear Information System (INIS)

    Barletta, W.A.; Fawley, W.M.; Judd, D.L.; Mark, J.W.K.; Yu, S.S.

    1984-01-01

    Recently revised estimates of target gain have added additional optimistic inputs to the interface between targets, accelerators and fusion chamber beam transport. But it remains valid that neutralization of the beams in the fusion chamber is useful if ion charge state Z > 1 or if > 1 kA per beamlet is to be propagated. Some engineering and economic considerations favor higher currents

  19. Human Enteroids as a Model of Upper Small Intestinal Ion Transport Physiology and Pathophysiology

    NARCIS (Netherlands)

    J. Foulke-Abel (Jennifer); J. In (Julie); Yin, J. (Jianyi); N.C. Zachos (Nicholas C.); O. Kovbasnjuk (Olga); M.K. Estes (Mary K.); H.R. de Jonge (Hugo); M. Donowitz (Mark)

    2016-01-01

    textabstractBackground & Aims Human intestinal crypt-derived enteroids are a model of intestinal ion transport that require validation by comparison with cell culture and animal models. We used human small intestinal enteroids to study neutral Na+ absorption and stimulated fluid and anion secretion

  20. Fast-ion transport induced by Alfvén eigenmodes in the ASDEX Upgrade tokamak

    DEFF Research Database (Denmark)

    Garcia-Munoz, M.; Classen, I.G.J.; Geiger, B.

    2011-01-01

    A comprehensive suite of diagnostics has allowed detailed measurements of the Alfvén eigenmode (AE) spatial structure and subsequent fast-ion transport in the ASDEX Upgrade (AUG) tokamak [1]. Reversed shear Alfvén eigenmodes (RSAEs) and toroidal induced Alfvén eigenmodes (TAEs) have been driven u...

  1. Role of external torque in the formation of ion thermal internal transport barriers

    Science.gov (United States)

    Jhang, Hogun; Kim, S. S.; Diamond, P. H.

    2012-04-01

    We present an analytic study of the impact of external torque on the formation of ion internal transport barriers (ITBs). A simple analytic relation representing the effect of low external torque on transport bifurcations is derived based on a two field transport model of pressure and toroidal momentum density. It is found that the application of an external torque can either facilitate or hamper bifurcation in heat flux driven plasmas depending on its sign relative to the direction of intrinsic torque. The ratio between radially integrated momentum (i.e., external torque) density to power input is shown to be a key macroscopic control parameter governing the characteristics of bifurcation.

  2. Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

    Science.gov (United States)

    Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

    2015-06-03

    On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

  3. Effect of Neoclassical Transport Optimization on Energetic Ion Confinement in LHD

    International Nuclear Information System (INIS)

    Murakami, S.; Yamada, H.; Sasao, M.

    2004-01-01

    Confinement of energetic ions from neutral beam injection heating is investigated by changing the magnetic field configuration of the Large Helical Device from a classical heliotron configuration to an optimized neoclassical transport configuration to a level typical of ''advanced stellarators.'' The experimental results show the highest count rate of fast neutral particles not in the optimized configuration but in the inward-shifted one. The GNET simulation results show a relatively good agreement with the experimental results, and they also show a lower energy loss rate in the optimized configuration. This contradiction can be explained by the radial profile of the energetic ions. The relatively good agreement between experimental and simulation results suggest that ripple transport (neoclassical) dominates the energetic ion confinement and that the optimization process is effective in improving confinement in helical systems

  4. Fully-kinetic Ion Simulation of Global Electrostatic Turbulent Transport in C-2U

    Science.gov (United States)

    Fulton, Daniel; Lau, Calvin; Bao, Jian; Lin, Zhihong; Tajima, Toshiki; TAE Team

    2017-10-01

    Understanding the nature of particle and energy transport in field-reversed configuration (FRC) plasmas is a crucial step towards an FRC-based fusion reactor. The C-2U device at Tri Alpha Energy (TAE) achieved macroscopically stable plasmas and electron energy confinement time which scaled favorably with electron temperature. This success led to experimental and theoretical investigation of turbulence in C-2U, including gyrokinetic ion simulations with the Gyrokinetic Toroidal Code (GTC). A primary objective of TAE's new C-2W device is to explore transport scaling in an extended parameter regime. In concert with the C-2W experimental campaign, numerical efforts have also been extended in A New Code (ANC) to use fully-kinetic (FK) ions and a Vlasov-Poisson field solver. Global FK ion simulations are presented. Future code development is also discussed.

  5. Connection of a He-jet recoil transport system to an ion source

    International Nuclear Information System (INIS)

    Sheppard, G.A.

    1977-02-01

    In an effort to make non-gaseous fission products available for on-line separation and study with the TRISTAN facility, an investigation of the operational characteristics of a He-jet recoil transport system and a TRISTAN-type ion source was conducted after interfacing them with a skimmer. So that experimental results could be understood and controlled, studies of the dynamics of choked flow in a capillary and of the transport characteristics were made. Satisfactory performance of the He-jet system was obtained, but large temperature and pressure gradients thwarted early attempts to efficiently couple the He-jet to the ion source. The pressure-related difficulties have been overcome by employing a skimmer to remove extraneous gases before injection of the activities into the ion source, but efforts to conquer the temperature-related problems continue

  6. Space charge compensation in the Linac4 low energy beam transport line with negative hydrogen ions

    Energy Technology Data Exchange (ETDEWEB)

    Valerio-Lizarraga, Cristhian A., E-mail: cristhian.alfonso.valerio.lizarraga@cern.ch [CERN, Geneva (Switzerland); Departamento de Investigación en Física, Universidad de Sonora, Hermosillo (Mexico); Lallement, Jean-Baptiste; Lettry, Jacques; Scrivens, Richard [CERN, Geneva (Switzerland); Leon-Monzon, Ildefonso [Facultad de Ciencias Fisico-Matematicas, Universidad Autónoma de Sinaloa, Culiacan (Mexico); Midttun, Øystein [CERN, Geneva (Switzerland); University of Oslo, Oslo (Norway)

    2014-02-15

    The space charge effect of low energy, unbunched ion beams can be compensated by the trapping of ions or electrons into the beam potential. This has been studied for the 45 keV negative hydrogen ion beam in the CERN Linac4 Low Energy Beam Transport using the package IBSimu [T. Kalvas et al., Rev. Sci. Instrum. 81, 02B703 (2010)], which allows the space charge calculation of the particle trajectories. The results of the beam simulations will be compared to emittance measurements of an H{sup −} beam at the CERN Linac4 3 MeV test stand, where the injection of hydrogen gas directly into the beam transport region has been used to modify the space charge compensation degree.

  7. Towards a heavy-ion transport capability in the MARS15 Code

    International Nuclear Information System (INIS)

    Mokhov, N.V.; Gudima, K.K.; Mashnik, S.G.; Rakhno, I.L.; Striganov, S.

    2004-01-01

    In order to meet the challenges of new accelerator and space projects and further improve modelling of radiation effects in microscopic objects, heavy-ion interaction and transport physics have been recently incorporated into the MARS15 Monte Carlo code. A brief description of new modules is given in comparison with experimental data. The MARS Monte Carlo code is widely used in numerous accelerator, detector, shielding and cosmic ray applications. The needs of the Relativistic Heavy-Ion Collider, Large Hadron Collider, Rare Isotope Accelerator and NASA projects have recently induced adding heavy-ion interaction and transport physics to the MARS15 code. The key modules of the new implementation are described below along with their comparisons to experimental data.

  8. Modeling of ion transport through a porous separator in vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zhao, T. S.; An, L.; Zeng, Y. K.; Wei, L.

    2016-09-01

    In this work, we develop a two-dimensional, transient model to investigate the mechanisms of ion-transport through a porous separator in VRFBs and their effects on battery performance. Commercial-available separators with pore sizes of around 45 nm are particularly investigated and effects of key separator design parameters and operation modes are explored. We reveal that: i) the transport mechanism of vanadium-ion crossover through available separators is predominated by convection; ii) reducing the pore size below 15 nm effectively minimizes the convection-driven vanadium-ion crossover, while further reduction in migration- and diffusion-driven vanadium-ion crossover can be achieved only when the pore size is reduced to the level close to the sizes of vanadium ions; and iii) operation modes that can affect the pressure at the separator/electrode interface, such as the electrolyte flow rate, exert a significant influence on the vanadium-ion crossover rate through the available separators, indicating that it is critically important to equalize the pressure on each half-cell of a power pack in practical applications.

  9. Ion transport through biological membranes an integrated theoretical approach

    CERN Document Server

    Mackey, Michael C

    1975-01-01

    This book illustrates some of the ways physics and mathematics have been, and are being, used to elucidate the underlying mechan­ isms of passive ion movement through biological membranes in general, and the membranes of excltable cells in particular. I have made no effort to be comprehensive in my introduction of biological material and the reader interested in a brief account of single cell electro­ physlology from a physically-oriented biologists viewpoint will find the chapters by Woodbury (1965) an excellent introduction. Part I is introductory in nature, exploring the basic electrical properties of inexcitable and excitable cell plasma membranes. Cable theory is utilized to illustrate the function of the non-decrementing action potential as a signaling mechanism for the long range trans­ mission of information in the nervous system, and to gain some in­ sight into the gross behaviour of neurons. The detailed analysis of Hodgkin and Huxley on the squid giant axon membrane ionic conductance properties...

  10. Design and characterization of a neutralized-transport experiment for heavy-ion fusion

    Directory of Open Access Journals (Sweden)

    Enrique Henestroza

    2004-08-01

    Full Text Available In heavy-ion inertial-confinement fusion systems, intense beams of ions must be transported from the exit of the final-focus magnet system through the fusion chamber to hit spots on the target with radii of about 2 mm. For the heavy-ion-fusion power-plant scenarios presently favored in the U.S., a substantial fraction of the ion-beam space charge must be neutralized during this final transport. The most effective neutralization technique found in numerical simulations is to pass each beam through a low-density plasma after the final focusing. To provide quantitative comparisons of these theoretical predictions with experiment, the Virtual National Laboratory for Heavy Ion Fusion has completed the construction and has begun experimentation with the neutralized-transport experiment. The experiment consists of three main sections, each with its own physics issues. The injector is designed to generate a very high-brightness, space-charge-dominated potassium beam, while still allowing variable perveance by a beam aperturing technique. The magnetic-focusing section, consisting of four pulsed quadrupoles, permits the study of magnet tuning, as well as the effects of phase-space dilution due to higher-order nonlinear fields. In the final section, the converging ion beam exiting the magnetic section is transported through a drift region with plasma sources for beam neutralization, and the final spot size is measured under various conditions of neutralization. In this paper, we discuss the design and characterization of the three sections in detail and present initial results from the experiment.

  11. Ion transport studies in lithium phospho-molybdate glasses containing Cl{sup −} ion

    Energy Technology Data Exchange (ETDEWEB)

    Gowda, V.C. Veeranna [Department of Physics, Government College for Women, Chintamani (India); Chethana, B.K. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore (India); Reddy, C. Narayana, E-mail: nivetejareddy@gmail.com [Department of Physics, Maharani' s Science College for Women, Bangalore (India)

    2013-07-01

    Highlights: • Addition of LiCl creates more conducting channels for Li{sup +} ion movement. • The decrease in E{sub dc} with increasing LiCl concentration could be due to Li{sup +} ions present in the columbic wells surrounded by Cl{sup −} ions are expected to be shallow. • Examined the power law fits using both two term and three term equation with fixed and floated parameters. -- Abstract: Ion conducting glasses in xLiCl–20Li{sub 2}O–(80−x) [0.80P{sub 2}O{sub 5}–0.20MoO{sub 3}] glass system have been prepared over a wide range of composition (X = 5, 10, 15, 20 and 25 mol%). The electrical conductivity and dielectric relaxation of these glasses were analyzed using impedance spectroscopy in the frequency range of 10 Hz–10 MHz and in the temperature range of 313–353 K. D.c. activation energies extracted from Arrhenius plots using regression analysis, decreases with increasing LiCl mol%. A.c. conductivity data has been fitted to both single and double power law equation with both fixed and variable parameters. The increased conductivity in the present glass system has been correlated with the volume increasing effect and the coordination changes that occur due to structural modification resulting in the creation of non-bridging oxygens (NBO's) of the type O-Mo-O{sup −} bonds in the glass network. Dielectric relaxation mechanism in these glasses is analyzed using Kohlrausch–Williams–Watts (KWW) stretched exponential function and stretched exponent (β) is found to be insensitive to temperature.

  12. Ion transport studies in lithium phospho-molybdate glasses containing Cl− ion

    International Nuclear Information System (INIS)

    Gowda, V.C. Veeranna; Chethana, B.K.; Reddy, C. Narayana

    2013-01-01

    Highlights: • Addition of LiCl creates more conducting channels for Li + ion movement. • The decrease in E dc with increasing LiCl concentration could be due to Li + ions present in the columbic wells surrounded by Cl − ions are expected to be shallow. • Examined the power law fits using both two term and three term equation with fixed and floated parameters. -- Abstract: Ion conducting glasses in xLiCl–20Li 2 O–(80−x) [0.80P 2 O 5 –0.20MoO 3 ] glass system have been prepared over a wide range of composition (X = 5, 10, 15, 20 and 25 mol%). The electrical conductivity and dielectric relaxation of these glasses were analyzed using impedance spectroscopy in the frequency range of 10 Hz–10 MHz and in the temperature range of 313–353 K. D.c. activation energies extracted from Arrhenius plots using regression analysis, decreases with increasing LiCl mol%. A.c. conductivity data has been fitted to both single and double power law equation with both fixed and variable parameters. The increased conductivity in the present glass system has been correlated with the volume increasing effect and the coordination changes that occur due to structural modification resulting in the creation of non-bridging oxygens (NBO's) of the type O-Mo-O − bonds in the glass network. Dielectric relaxation mechanism in these glasses is analyzed using Kohlrausch–Williams–Watts (KWW) stretched exponential function and stretched exponent (β) is found to be insensitive to temperature

  13. Fast-ion transport in the presence of magnetic reconnection induced by sawtooth oscillations in ASDEX Upgrade

    NARCIS (Netherlands)

    Geiger, B.; M. García-Muñoz,; Dux, R.; Ryter, F.; Tardini, G.; Orte, L. B.; Classen, I.G.J.; Fable, E.; Fischer, R.; Igochine, V.; McDermott, R. M.

    2014-01-01

    The transport of beam-generated fast ions has been investigated experimentally at the ASDEX Upgrade tokamak in the presence of sawtooth crashes. After sawtooth crashes, phase space resolved fast-ion D-alpha measurements show a significant reduction of the central fast-ion density-more than

  14. Diagnostics of discharge channels for neutralized chamber transport in heavy ion fusion

    International Nuclear Information System (INIS)

    Niemann, C.; Penache, D.; Tauschwitz, A.; Rosmej, F.B.; Neff, S.; Birkner, R.; Constantin, C.; Knobloch, R.; Presura, R.; Yu, S.S.; Sharp, W.M.; Ponce, D.M.; Hoffmann, D.H.H.

    2002-01-01

    The final beam transport in the reactor chamber for heavy ion fusion in preformed plasma channels offers many attractive advantages compared to other transport modes. In the past few years, experiments at the Gesellschaft fuer Schwerionenforschung (GSI) accelerator facility have addressed the creation and investigation of discharge plasmas, designed for the transport of intense ion beams. Stable, self-standing channels of 50 cm length with currents up to 55 kA were initiated in low-pressure ammonia gas by a CO 2 -laser pulse along the channel axis before the discharge is triggered. The channels were characterized by several plasma diagnostics including interferometry and spectroscopy. We also present first experiments on laser-guided intersecting discharges

  15. Regulation of the glutamine transporter SN1 by extracellular pH and intracellular sodium ions

    International Nuclear Information System (INIS)

    Broeer, A.; Broeer, S.; Setiawan, I.; Lang, F.

    2001-01-01

    Full text: SN1 has recently been identified as one of the major glutamine transporters in hepatocytes and brain astrocytes. It appears to be the molecular correlate of the system N amino acid transporter. Two different transport mechanisms have been proposed for this transporter. Either an electroneutral mechanism, in which glutamine uptake is coupled to an exchange of 1Na + and 1H + , or an electrogenic mechanism coupled to the exchange of 2Na + against 1H + . This study was performed to solve the discrepancies and to investigate the reversibility of the transporter. When expressed in Xenopus laevis oocytes glutamine uptake activity increased strongly with increasing pH. In agreement with the pH-dependence we found that uptake of glutamine was accompanied by an alkalization of the cytosol, indicating that SN1 mediates Glutamine/H + -Antiport. Uptake of glutamine into oocytes was Na + -dependent. Analysis of the Na + -dependence of glutamine transport and Flux studies using 22 Na + indicated that two or more sodium ions were cotransported together with glutamine. However, at the same time intracellular Na + was exchanged against extracellular Na + . Taken together with the results of the pH-dependence it is proposed that SN1 mediates a Na + /Na + -exchange and a Na + /H + -exchange, both being coupled to the transport of glutamine. In agreement with this mechanism we found that acidic pH caused a reversal of the transporter. To investigate the source of the glutamine-induced inward currents, we compared inward currents generated by the 1Na + /glutamine cotransporter ATA1 with those generated by SN1. Currents induced by glutamine uptake in SN1 expressing oocytes were only a fraction of the currents induced by glutamine in ATA1 expressing oocytes, indicating that they were not generated by a stoichiometric uptake of ions. It is concluded that SN1 is tightly regulated by pH and intracellular Na + -ions and is capable of mediating glutamine uptake and release

  16. Power dependence of ion thermal diffusivity at the internal transport barrier in JT-60U

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Yoshiteru; Suzuki, Takahiro; Ide, Shunsuke [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment] [and others

    2002-09-01

    The formation properties of an internal transport barrier (ITB) were investigated in a weak positive magnetic shear plasma by changing the neutral beam heating power. The ion thermal diffusivity in the core region shows L-mode state, weak ITB, and strong ITB, depending upon the heating power. Two features of ITB formation were experimentally confirmed. Weak ITB was formed in spite of the absence of an apparent transition in an ion temperature profile. On the other hand, strong ITB appeared after an apparent transition from the weak ITB. In addition, the ion thermal diffusivity at the ITB is correlated to the radial electric field shear. In the case of the weak ITB, ion thermal diffusivity decreased gradually with increases in the radial electric field shear. There exists a threshold in the radial electric field shear, which allows for a change in state from that of weak to strong ITBs. (author)

  17. Modeling of Low Frequency MHD Induced Beam Ion Transport In NSTX

    International Nuclear Information System (INIS)

    Gorelenkov, N.N.; Medley, S.S.

    2004-01-01

    Beam ion transport in the presence of low frequency MHD activity in National Spherical Tokamak Experiment (NSTX) plasma is modeled numerically and analyzed theoretically in order to understand basic underlying physical mechanisms responsible for the observed fast ion redistribution and losses. Numerical modeling of the beam ions flux into the NPA in NSTX shows that after the onset of low frequency MHD activity high energy part of beam ion distribution, E b > 40keV, is redistributed radially due to stochastic diffusion. Such diffusion is caused by high order harmonics of the transit frequency resonance overlap in the phase space. Large drift orbit radial width induces such high order resonances. Characteristic confinement time is deduced from the measured NPA energy spectrum and is typically ∼ 4msec. Considered MHD activity may induce losses on the order of 10% at the internal magnetic field perturbation (delta)B/B = Ο (10 -3 ), which is comparable to the prompt orbit losses

  18. Innovative alpha radioactivity monitor for clearance level inspection based on ionized air transport technology (2). CFD-simulated and experimental ion transport efficiencies for uranium-attached pipes

    International Nuclear Information System (INIS)

    Hirata, Yosuke; Nakahara, Katsuhiko; Sano, Akira; Sato, Mitsuyoshi; Aoyama, Yoshio; Miyamoto, Yasuaki; Yamaguchi, Hiromi; Nanbu, Kenichi; Takahashi, Hiroyuki; Oda, Akinori

    2007-01-01

    An innovative alpha radioactivity monitor for clearance level inspection has been developed. This apparatus measures an ion current resulting from air ionization by alpha particles. Ions generated in the measurement chamber of about 1 m 3 in volume are transported by airflow to a sensor and measured. This paper presents computational estimation of ion transport efficiencies for two pipes with different lengths, the inner surfaces of which were covered with a thin layer of uranium. These ion transport efficiencies were compared with those experimentally obtained for the purpose of our model validation. Good agreement was observed between transport efficiencies from simulations and those experimentally estimated. Dependence of the transport efficiencies on the region of uranium coating was also examined, based on which anticipated errors arising from unclear positions of contamination are also discussed. (author)

  19. Experimental study of the transport limits of intense heavy ion beams in the HCX

    International Nuclear Information System (INIS)

    Prost, L.R.; Bieniosek, F.M.; Celata, C.M.; Dugan, C.C.; Faltens, A.; Seidl, P.A.; Waldron, W.L.; Cohen, R.; Friedman, A.; Kireeff Covo, M.; Lund, S.M.; Molvik, A.W.; Haber, I.

    2004-01-01

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high space-charge intensity (line charge density up to ∼ 0.2 (micro)C/m) over long pulse durations (4 (micro)s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. The experiment also contributes to the practical baseline knowledge of intense beam manipulations necessary for the design, construction and operation of a heavy ion driver for inertial fusion. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, electron cloud effects, and longitudinal bunch control. We first present the results for a coasting 1 MeV K + ion beam transported through the first ten electrostatic transport quadrupoles, measured with optical beam-imaging and double-slit phase-space diagnostics. This includes studies at two different radial fill factors (60% and 80%), for which the beam transverse distribution was characterized in detail. Additionally, beam energy measurements will be shown. We then discuss the first results of beam transport through four pulsed room-temperature magnetic quadrupoles (located downstream of the electrostatic quadrupoles), where the beam dynamics become more sensitive to the presence of secondary electrons

  20. The two Na+ sites in the human serotonin transporter play distinct roles in the ion coupling and electrogenicity of transport.

    Science.gov (United States)

    Felts, Bruce; Pramod, Akula Bala; Sandtner, Walter; Burbach, Nathan; Bulling, Simon; Sitte, Harald H; Henry, L Keith

    2014-01-17

    Neurotransmitter transporters of the SLC6 family of proteins, including the human serotonin transporter (hSERT), utilize Na(+), Cl(-), and K(+) gradients to induce conformational changes necessary for substrate translocation. Dysregulation of ion movement through monoamine transporters has been shown to impact neuronal firing potentials and could play a role in pathophysiologies, such as depression and anxiety. Despite multiple crystal structures of prokaryotic and eukaryotic SLC transporters indicating the location of both (or one) conserved Na(+)-binding sites (termed Na1 and Na2), much remains uncertain in regard to the movements and contributions of these cation-binding sites in the transport process. In this study, we utilize the unique properties of a mutation of hSERT at a single, highly conserved asparagine on TM1 (Asn-101) to provide several lines of evidence demonstrating mechanistically distinct roles for Na1 and Na2. Mutations at Asn-101 alter the cation dependence of the transporter, allowing Ca(2+) (but not other cations) to functionally replace Na(+) for driving transport and promoting 5-hydroxytryptamine (5-HT)-dependent conformational changes. Furthermore, in two-electrode voltage clamp studies in Xenopus oocytes, both Ca(2+) and Na(+) illicit 5-HT-induced currents in the Asn-101 mutants and reveal that, although Ca(2+) promotes substrate-induced current, it does not appear to be the charge carrier during 5-HT transport. These findings, in addition to functional evaluation of Na1 and Na2 site mutants, reveal separate roles for Na1 and Na2 and provide insight into initiation of the translocation process as well as a mechanism whereby the reported SERT stoichiometry can be obtained despite the presence of two putative Na(+)-binding sites.