WorldWideScience

Sample records for beta drift waves

  1. Finite-beta and curvature drift effects on drift waves near the plasmapause

    International Nuclear Information System (INIS)

    The linear stability of finite-#betta# drift waves, near the plasmapause of the earth, is analysed for the case in which the magnetic field is non-uniform in two dimensions. The coupling of the driftwave to the oscillation of the magnetic field, due to non-zero #betta#, is found to be destabilizing. The spatial structure of the unstable mode is found to be governed by the 'curvature' scale length of the equilibrium magnetic field. (author)

  2. Theory and calculation of finite beta drift wave turbulence

    International Nuclear Information System (INIS)

    Using numerical techniques, we calculate eigenmodes of the nonlinear universal mode with finite beta in order to determine the scaling of the saturation level of the instability with beta. We use two different renormalizations in the calculations and find that using the appropriate renormalization, we are able to recover Alcator density scaling, as originally found in analytic work by Molvig and Hirshman. We also find that the universal mode should be stable in ohmically heated tokamaks above a critical beta on the order of 0.02

  3. Modulational instability of drift waves

    International Nuclear Information System (INIS)

    The instability of drift waves against zonal flows and streamers is discussed. Unlike in previous treatments, we do not make the assumption that their frequency is resonant with drift wave packets. In this more general treatment we find at least two unstable roots even in the simple case of a monochromatic pump drift wave, and potentially an infinite multitude of roots for a more complicated drift wave spectrum. One of them is the well known modulational instability in resonance with the drift wave packets; the other is a new instability corresponding to the inelastic refraction of drift waves at the streamer. It is nontrivial which of the many roots is the most unstable one

  4. Collisional drift fluids and drift waves

    International Nuclear Information System (INIS)

    The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effect of which is extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter is important as concerns charge separation and resulting electric fields which are possibly related to the L-H transition. Energy conservation is crucial for the stability behaviour; it will be discussed via an example. New collisional multispecies drift-fluid equations were derived by a new method which yields in a transparent way conservation of energy and total angular momentum, and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The method is based primarily on a Lagrangian for dissipationless fluids in drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. Their relation to the ideal equations imply, however, also a relation to the ideal Lagrangian of which one can take advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. Tν(x)=const. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theories; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. Linear instability is investigated via energy considerations and the implications of taking ohmic resistivity into account are discussed. (orig./WL)

  5. Drift waves in general toroidal geometry

    International Nuclear Information System (INIS)

    A model, based on gyro-kinetic ions and fluid electrons, to study drift waves in low-beta [beta = (kinetic pressure)/(magnetic pressure)] stellarator plasmas is presented. The model equations are written in straight-field-line coordinates and are valid for arbitrary, fully three-dimensional configurations with closed, nested magnetic surfaces. An implicit method, coupled with a subcycling technique for the electrons, is used to solve the time-dependent, along-the-field-line equations. Numerical calculations are carried out for a 3-field-period toroidal heliac. The geometrical effects that enter the model equations are calculated and displayed in physical space using advanced visualization techniques

  6. Clumps in drift wave turbulence

    DEFF Research Database (Denmark)

    Pecseli, H. L.; Mikkelsen, Torben

    1986-01-01

    , two-dimensional random flow serves as a particularly simple illustration. For this case particles can be trapped for all times in a local vortex (macro-clump). A small test-cloud of particles (micro-clump) chosen arbitrarily in a realization will on the other hand expand on average. A formulation is...... proposed in terms of conditional eddies, in order to discriminate turbulent flows where macro-clumps may be observed. The analysis is illustrated by results from experimental investigations of strongly turbulent, resistive drift-wave fluctuations. The related problem for electrostatic turbulence in...

  7. Kinetic theory of drift waves

    International Nuclear Information System (INIS)

    The linear stability of the electrostatic drift waves in slab geometry has been studied analytically and numerically. The effects of magnetic field with shear, of the finite Larmor radius, of an electron streaming, of a temperature gradient and of collisions have been retained. The analytical solution has been obtained using the matched asymptotic expansion technique, and an expression for the critical streaming parameter has been derived. Finally, assuming that the transport in the Reversed Field Pinches is dominated by this instability, a scaling law for the temperature in such machine is derived

  8. Counting of discrete Rossby/drift wave resonant triads

    CERN Document Server

    Bustamante, Miguel D; Lynch, Peter; Quinn, Brenda

    2013-01-01

    The purpose of this note is to remove the confusion about counting of resonant wave triads for Rossby and drift waves in the context of the Charney-Hasegawa-Mima equation. In particular, we aim to point out a major error of over-counting of triads in the paper "Discrete exact and quasi-resonances of Rossby/drift waves on beta-plane with periodic boundary conditions", by Kartashov and Kartashova, arXiv:1307.8272v1 [physics.flu-dyn] (2013).

  9. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    Samiran Ghosh; Nikhil Chakrabarti; Manoranjan Khan; M R Gupta

    2013-02-01

    The conditions for the existence of low-frequency electrostatic drift wave in pair-ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  10. Anomalous bootstrap current due to drift waves

    International Nuclear Information System (INIS)

    An anomalous parallel current driven by radial flux in tokamak is discussed. Drift waves, which cause an anomalous cross field diffusion, can generate a parallel current in a sheared magnetic field, if the fluctuation level has radial dependence. (author)

  11. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  12. Drift Wave Turbulence and Magnetic Reconnection

    Science.gov (United States)

    Price, L.; Drake, J. F.; Swisdak, M.

    2015-12-01

    An important feature in collisionless magnetic reconnection is the development of sharp discontinuities along the separatrices bounding the Alfvenic outflow. The typical scale length of these features is ρs (the Larmor radius based on the sound speed) for guide field reconnection. Temperature gradients in the inflowing plasma (as might be found in the magnetopause and the magnetotail) can lead to instabilities at these separatrices, specifically drift wave turbulence. We present standalone 2D and 3D PIC simulations of drift wave turbulence to investigate scaling properties and growth rates. We specifically consider stabilization of the lower hybrid drift instability (LHDI) and the development of this instability in the presence of a sheared magnetic field. Further investigations of the relative importance of drift wave turbulence in the development of reconnection will also be considered.

  13. Collisional drift fluid equations and implications for drift waves

    International Nuclear Information System (INIS)

    The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effects of which are extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter law is important in relation to charge separation and the resulting electric fields, which are possibly related to the L-H transition. Energy conservation is crucial to the stability behaviour, it will be discussed by means of an example. New collisional multi-species drift-fluid equations were derived by a new method which yields, in a transparent way, conservation of energy and total angular momentum and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The only restriction involved is the validity of the drift approximation; in particular, there are no assumptions restricting the geometry of the system. The method is based primarily on a Lagrangian for dissipationless fluids in the drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. However, their relation to the ideal equations also implies a relation to the ideal Lagrangian, which can be used to advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. Tv(x) = constant. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theory; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. (author)

  14. Nonlinear dynamics of resistive electrostatic drift waves

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Pécseli, H.L.

    1999-01-01

    The evolution of weakly nonlinear electrostatic drift waves in an externally imposed strong homogeneous magnetic field is investigated numerically in three spatial dimensions. The analysis is based on a set of coupled, nonlinear equations, which are solved for an initial condition which is...... polarity, i.e. a pair of electrostatic convective cells....

  15. Drift wave solitons in an inhomogeneous magnetized plasma

    International Nuclear Information System (INIS)

    The shears of electron diamagnetic drift velocity and ExB drift velocity are theoretically verified to give nonlinearities and establish a soliton of drift wave. Experimentally, a drift wave soliton is observed. Both of the propagation velocity of the soliton and the inverse of the soliton width get large with an increase in amplitude. (author)

  16. Nonlinear radial propagation of drift wave turbulence

    International Nuclear Information System (INIS)

    We study the linear and the nonlinear radial propagation of drift wave energy in an inhomogeneous plasma. The drift mode excited in such a plasma is dispersive in nature. The drift wave energy spreads out symmetrically along the direction of inhomogeneity with a finite group velocity. To study the effect of the nonlinear coupling on the propagation of energy in a collision free plasma, we solve the Hasegawa-Mima equation as a mixed initial boundary-value problem. The solutions of the linearized equation are used to check the reliability of our numerical calculations. Additional checks are also performed on the invariants of the system. Our results reveal that a pulse gets distorted as it propagates through the medium. The peak of the pulse propagates with a finite velocity that depends on the amplitude of the initial pulse. The polarity of propagation depends on the initial parameters of the pulse. We have also studied drift wave propagation in a resistive plasma. The Hasegawa-Wakatani equations are used to investigate this problem

  17. The Absence of Stokes Drift in Waves

    CERN Document Server

    Chafin, Clifford

    2015-01-01

    Stokes drift has been as central to the history of wave theory as it has been distressingly absent from experiment. Neither wave tanks nor experiments in open bodies detect this without nearly canceling "eulerian flows." Acoustic waves have an analogous problem that is particularly problematic in the vorticity production at the edges of beams. Here we demonstrate that the explanation for this arises from subtle end-of-packet and wavetrain gradient effects such as microbreaking events and wave-flow decomposition subtleties required to conserve mass and momentum and avoid fictitious external forces. These losses occur at both ends of packets and can produce a significant nonviscous energy loss for translating and spreading surface wave packets and wavetrains. In contrast, monochromatic sound wave packets will be shown to asymmetrically distort to conserve momentum. This provides an interesting analogy to how such internal forces arise for gradients of electromagnetic wavetrains in media. Such examples show that...

  18. Amplitude modulated drift wave packets in a nonuniform magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, P.K., E-mail: profshukla@yahoo.de [International Centre for Advanced Studies in Physical Sciences and Institute for Theoretical Physics, Faculty of Physics and Astronomy, Ruhr University Bochum, D-447 80 Bochum (Germany); Misra, A.P., E-mail: apmisra@gmail.com [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan 731 235 (India)

    2012-08-06

    We consider the amplitude modulation of low-frequency, long wavelength electrostatic drift wave packets in a nonuniform magnetoplasma with the effects of equilibrium density, electron temperature and magnetic field inhomogeneities. The dynamics of the modulated drift wave packet is governed by a nonlinear Schrödinger equation. The latter is used to study the modulational instability of a Stoke's wave train to a small longitudinal perturbation. It is shown that the drift wave packet is stable (unstable) against the modulation when the drift wave number lies in 0drift wave packet can propagate in the form of bright and dark envelope solitons or as a drift wave rogon.

  19. Drift wave vortices and anomalous transport

    International Nuclear Information System (INIS)

    Theory and computer simulations are used to describe the inelastic vortex-vortex and vortex-wave interactions that lead to the quasi-coherent transport of plasma across the magnetic field. Monopole and dipole drift wave vortices with radii r0 large compared with the ion inertial scale length /rho//sub s/ are shown to produce transport at the rate un/sub υ/∫dσ(b) ≤ n/sub υ/υ/sub de/r/sub o/ where n/sub υ/ is the vortex line density and dσ(b) is the inelastic collision cross-section for impact parameter b. The transport during collisions and mergings is evaluated from the evolution of a passively convected scalar concentration of test particles. 24 refs., 4 figs

  20. Global kink and ballooning modes in high-beta systems and stability of toroidal drift modes

    International Nuclear Information System (INIS)

    A numerical code (HBT) has been developed which solves for the equilibrium, global stability and high-n stability of plasmas with arbitrary cross-section. Various plasmas are analysed for their stability to these modes in the high-beta limit. Screw-pinch equilibria are stable to high-n ballooning modes up to betas of 18%. The eigenmode equation for drift waves is analysed numerically. The toroidal branch is shown to be destabilized by the non-adiabatic response of trapped and circulating particles. (author)

  1. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two...

  2. Experiment and theory of a drift wave in the levitated octupole

    International Nuclear Information System (INIS)

    A very coherent 30 kHz drift wave is observed in the Levitated Toroidal Octupole at the University of Wisconsin - Madison. The density and floating potential fluctuations have a well-defined spatial structure in the poloidal magnetic field. Radially the wave has a standing wave structure with amplitude peaked in regions of locally bad magnetic curvature. Poloidally the wave has a standing wave structure with odd symmetry; nodes are located in the regions of locally good magnetic curvature. The wave propagates toroidally in the electron diamagnetic drift direction with a wavelength of 20 centimeters. No changes occur in the wave structure as the plasma is varied over three orders of magnitude in density and beta

  3. Drift wave instability in the Io plasma torus

    Science.gov (United States)

    Huang, T. S.; Hill, T. W.

    1991-01-01

    A linear normal mode analysis of the drift wave instability in the Io plasma torus was carried out on the basis of the Richmond (1973) and Huang et al. (1990) analyses of drift waves in the vicinity of the earth's plasmapause. Results indicate that the outer torus boundary is linearly unstable to the growth of electrostatic drift waves. It is shown that the linear growth rate is proportional to the ion drift frequency and to the ratio of the flux tube charge content to the Jovian ionospheric Pedersen conductance. It is also shown that various theoretical models of global radial transport in Jupiter's atmosphere (including corotating convection, interchange diffusion, and transient flux tube convection) can be understood as plausible nonlinear evolutions of electrostatic drift waves.

  4. Strong turbulence of drift-waves in Hamiltonian canonical description

    International Nuclear Information System (INIS)

    Starting with a Hamiltonian formulation of the Hasegawa-Mima equation, the statistical theory of strong turbulence of nonlinear drift-waves in plasmas is developed. The procedure is based on the direct-interaction-approximation (DIA)

  5. Resistive drift wave turbulence in a three-dimensional geometry

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Michelsen, Poul; Naulin, V.

    1999-01-01

    The Hasegawa-Wakatani model describing resistive drift waves is investigated analytically and numerically in a three-dimensional periodic geometry. After an initial growth of the energy the drift waves couple nonlinearly to convective cells, which eventually dominate the system completely. An app...... approach to include more physical boundary conditions to the system is presented. This changes the results of the simulations significantly. (C) 1999 American Institute of Physics.......The Hasegawa-Wakatani model describing resistive drift waves is investigated analytically and numerically in a three-dimensional periodic geometry. After an initial growth of the energy the drift waves couple nonlinearly to convective cells, which eventually dominate the system completely. An...

  6. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  7. Scroll wave drift along steps, troughs, and corners

    Science.gov (United States)

    Ke, Hua; Zhang, Zhihui; Steinbock, Oliver

    2015-06-01

    Three-dimensional excitable systems can create nonlinear scroll waves that rotate around one-dimensional phase singularities. Recent theoretical work predicts that these filaments drift along step-like height variations. Here, we test this prediction using experiments with thin layers of the Belousov-Zhabotinsky reaction. We observe that over short distances scroll waves are attracted towards the step and then rapidly commence a steady drift along the step line. The translating filaments always reside on the shallow side of the step near the edge. Accordingly, filaments in the deep domain initially collide with and shorten at the step wall. The drift speeds obey the predicted proportional dependence on the logarithm of the height ratio and the direction depends on the vortex chirality. We also observe drift along the perimeter of rectangular plateaus and find that the filaments perform sharp turns at the corners. In addition, we investigate rectangular troughs for which vortices of equal chirality can drift in different directions. The latter two effects are reproduced in numerical simulations with the Barkley model. The simulations show that narrow troughs instigate scroll wave encounters that induce repulsive interaction and symmetry breaking. Similar phenomena could exist in the geometrically complicated ventricles of the human heart where reentrant vortex waves cause tachycardia and fibrillation.

  8. Fluctuation and thermal energy balance for drift-wave turbulence

    International Nuclear Information System (INIS)

    Energy conservation for the drift-wave system is shown to be separated into the wave-energy power balance equation and an ambient thermal-energy transport equation containing the anomalous transport fluxes produced by the fluctuations. The wave energy equation relates the wave energy density and wave energy flux to the anomalous transport flux and the dissipation of the fluctuations. The thermal balance equation determines the evolution of the temperature profiles from the divergence of the anomalous heat flux, the collisional heating and cooling mechanisms and the toroidal pumping effect. 16 refs., 1 tab

  9. Toroidal drift waves with an equilibrium velocity field

    International Nuclear Information System (INIS)

    The author investigated the effect of a radially sheared poloidal velocity field on the toroidal drift wave which is well known to escape magnetic shear damping through toroidal coupling between different poloidal harmonics centered on individual rational surfaces. He endeavored to model the velocity profile according to that observed at the plasma edge during H-mode shots. The resultant wave formed by the interference of different poloidal harmonics now sees an antiwell created by the H-mode type velocity profile in the radial direction (in contrast to a well formed by the diamagnetic frequency in the absence of velocity fields). The wave, therefore, convects energy outward and hence undergoes damping. Outgoing wave boundary condition then introduces a negative imaginary contribution to the global eigenvalue -- once again confirming the stabilizing role of H-mode type velocity profiles. On the other hand, L-mode type velocity profiles have destabilizing action on toroidal drift waves

  10. Slow Drift-Oscillations of a Ship in Irregular Waves

    Directory of Open Access Journals (Sweden)

    Odd M. Faltinsen

    1980-10-01

    Full Text Available A procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented. The hydrodynamic boundary-value problem is solved correctly to second order in wave amplitude. Results in the form of second order transfer functions are presented for different, two-dimensional shapes. It is concluded that Newman's approximative method is a practical way to calculate slow drift excitation forces on a ship in beam sea and it is suggested that it may be used in a more general case. Applications of the results for moored ships are discussed.

  11. Point vortex description of drift wave vortices: Dynamics and transport

    International Nuclear Information System (INIS)

    Point vortex description for drift wave vortices is formulated based on the Hasegawa-Mima equation to study elementary processes for the interactions of vortices as well as statistical properties like vortex diffusion. Dynamical properties of drift wave vortices known by numerical experiments are recovered. Furthermore a vortex diffusion model discussed by Horton based on numerical simulations is shown to be analytically obtained. A variety of phenomena arising from the short-range nature of the interaction force of point vortices are suggested. 9 refs., 6 figs

  12. Counting of discrete Rossby/drift wave resonant triads (again)

    CERN Document Server

    Bustamante, Miguel D; Lynch, Peter; Quinn, Brenda

    2013-01-01

    The purpose of our earlier note (arXiv:1309.0405 [physics.flu-dyn]) was to remove the confusion over counting of resonant wave triads for Rossby and drift waves in the context of the Charney-Hasegawa-Mima equation. A comment by Kartashov and Kartashova (arXiv:1309.0992v1 [physics.flu-dyn]) on that note has further confused the situation. The present note aims to remove this obfuscation.

  13. Three-dimensional drift chambers of the DCBA experiment for neutrinoless double beta decay search

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, T., E-mail: ishikawat@hakone.phys.metro-u.ac.j [Tokyo Metropolitan University, Hachioji, Tokyo 192-0398 (Japan); Igarashi, H.; Sumiyoshi, T. [Tokyo Metropolitan University, Hachioji, Tokyo 192-0398 (Japan); Ishihara, N.; Iwai, G.; Iwase, H.; Kato, Y.; Kawai, M.; Kondou, Y.; Haruyama, T.; Inagaki, T.; Makida, Y.; Ohama, T.; Takahashi, K.; Yamada, Y. [High Energy Accel, Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Tashiro, E.; Ishizuka, T. [Shizuoka University, Naka, Hamamatsu, Shizuoka 432-8011 (Japan); Kitamura, S. [Nihon Institute of Medical Science, Iruma-gun, Saitama 350-0435 (Japan); Teramoto, Y. [Osaka City University, Sumiyoshi, Osaka 558-8585 (Japan); Nakano, I. [Okayama University, Okayama 700-8530 (Japan)

    2011-02-01

    The aim of the DCBA (Drift Chamber Beta-ray Analyzer) experiment is to search for neutrinoless double beta decay (0{nu}{beta}{beta}). The half-life of 0{nu}{beta}{beta} is expected to give us the information of Majorana nature and the absolute mass scale of neutrinos. A prototype test apparatus DCBA-T2 has the energy resolution of about 150 keV (FWHM) around 1 MeV. In order to check the detector performance, engineering runs detecting double beta decay of {sup 100}Mo started in May 2009 using natural Mo, which contains 9.6% of {sup 100}Mo. Ten candidates of the double beta decay ({beta}{beta}) have been detected so far. It has been found that the background events due to {sup 214}Bi decay are distinguishable from the double beta decays by detecting {alpha}-particles from {sup 214}Po.

  14. Lyapunov exponents and particle dispersion in drift wave turbulence

    DEFF Research Database (Denmark)

    Pedersen, T.S.; Michelsen, Poul; Juul Rasmussen, J.

    1996-01-01

    The Hasegawa-Wakatani model equations for resistive drift waves are solved numerically for a range of values of the coupling due to the parallel electron motion. The largest Lyapunov exponent, lambda(1), is calculated to quantify the unpredictability of the turbulent flow and compared to other...

  15. Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma

    Czech Academy of Sciences Publication Activity Database

    Martines, E.; Zuin, M.; Cavazzana, R.; Adámek, Jiří; Antoni, V.; Serianni, G.; Spolaore, M.; Vianello, N.

    2014-01-01

    Roč. 21, č. 10 (2014), s. 102309-102309. ISSN 1070-664X Institutional support: RVO:61389021 Keywords : Drift waves * Magnetron sputtering plasma * Spatiotemporal synchronization Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.142, year: 2014 http://dx.doi.org/10.1063/1.4898693

  16. Stability criteria for current-driven drift wave eigenmodes

    International Nuclear Information System (INIS)

    Eigenmodes of current-driven collisionless electrostatic drift waves in a sheared magnetic field are re-examined in the light of the recent discovery that their non-current-driven counterparts are stable. Conditions for instability are determined from numerical finite difference and variational solutions of the slab model differential equation. It is found that three stringent conditions are required for instability: (1) very weak shear, (2) low ion temperature, and (3) very large parallel drift velocity. For L/sub n//L/sub s/=0.02 and T/sub i//T/sub e/=0, the instability threshold is u/sub d//c/sub s/=0.85, where L/sub n/ and L/sub s/ are the density and shear scale lengths, respectively, u/sub d/ is the drift velocity, and c/sub s/ is the sound speed. For larger shear and finite ion temperature the critical drift velocity is even larger. It is concluded that drift wave fluctuations in tokamaks cannot be described in terms of these eigenmodes

  17. Global Theory to Understand Toroidal Drift Waves in Steep Gradient

    CERN Document Server

    Xie, Hua-Sheng

    2016-01-01

    Toroidal drift waves with unconventional mode structures and non-ground eigenstates, which differ from typical ballooning structure mode, are found to be important recently by large scale global gyrokinetic simulations and especially become dominant at strong gradient edge plasmas [cf., Xie and Xiao, Phys. Plasmas, 22, 090703 (2015)]. The global stability and mode structures of drift wave in this steep edge density and temperature gradients are examined by both direct numerical solutions of a model two-dimensional eigen equation and analytical theory employing WKB-ballooning approach. Theory agrees with numerical solutions quite well. Our results indicate that (i) non-ground eigenstates and unconventional mode structures generally exist and can be roughly described by two parameters `quantum number' $l$ and ballooning angle $\\vartheta_k$, (ii) local model can overestimate the growth rate largely, say, $>50\\%$, and (iii) the narrow steep equilibrium profile leads to twisting (triangle-like) radial mode structu...

  18. Wave-like structures within ionospheric drift data series

    Czech Academy of Sciences Publication Activity Database

    Kouba, Daniel

    Prague: International Union of Geodesy and Geophysics, 2015. A12p-156. [Earth and Environmental Sciences for Future Generations. General Assembly of International Union of Geodesy and Geophysics /26./. 22.06.2015-02.07.2015, Prague] Institutional support: RVO:68378289 Keywords : wave-like structures * ionospheric drift Subject RIV: DG - Athmosphere Sciences, Meteorology http://www.iugg2015prague.com/abstractcd/ data /HtmlApp/main.html#

  19. Simulations of drift waves in 3D magnetic configurations

    International Nuclear Information System (INIS)

    Drift waves are commonly held responsible for anomalous transport in tokamak configurations and in particular for the anomalously high heat loss. The next generation of stellarators on the other hand are hoped to be characterized by a much smaller neo-classical transport and by particle confinement close to that of tokamaks. There is nevertheless a strong interest in the stellarator community to study the properties of drift waves in 3D magnetic configurations. To serve this interest we have developed the first global gyrokinetic code, EUTERPE, aimed at the investigation of linear drift wave stability in general toroidal geometry. The physical model assumes electrostatic waves and adiabatic electrons. EUTERPE is a particle-in-cell (PIC) code in which the gyrokinetic Poisson equation is discretized with the finite element method defined in the PEST -1 system of magnetic coordinates. The magnetic geometry is provided by the magnetohydrodynamic (MHD) equilibrium code VMEC. The complete 3D model has been successfully validated in toroidal axisymmetric and straight helical geometries and has permitted the first simulation of unstable global ITG driven modes in non-axisymmetric toroidal configurations. As a first application, two configurations have been studied, the Quasi-Axially symmetric Stellarator with three fields periods (QAS3) currently one system under consideration at the Princeton Plasma Physics Laboratory and the Helically Symmetric experiment (HSX) which has recently started operation at the University of Wisconsin. QAS3 is characterized by a tokamak-Iike field in the outer part of the torus. In this structure the drift waves are mainly affected by the magnetic shear and barely by the shape of the plasma. Also, the results are very close to those obtained for a tokamak. On the other hand, results for the HSX configuration, which is characterized by a dominant helical magnetic field, show a clear 3D effect, namely a strong toroidal variation of the drift wave

  20. Transport of parallel momentum by collisionless drift wave turbulence

    DEFF Research Database (Denmark)

    Diamond, P.H.; McDevitt, C.J.; Gürcan, O.D.;

    2008-01-01

    This paper presents a novel, unified approach to the theory of turbulent transport of parallel momentum by collisionless drift waves. The physics of resonant and nonresonant off-diagonal contributions to the momentum flux is emphasized, and collisionless momentum exchange between waves and...... contributes significantly to the residual stress. A general equation for mean k(parallel to) () is derived and used to develop a generalized theory of symmetry breaking. The resonant particle momentum flux is calculated, and pinch and residual stress effects are identified. The implications of...

  1. Transport of parallel momentum by collisionless drift wave turbulence

    DEFF Research Database (Denmark)

    Diamond, P.H.; McDevitt, C.J.; Gurcan, O.E.;

    2008-01-01

    This paper presents a novel, unified approach to the theory of turbulent transport of parallel momentum by collisionless drift waves. The physics of resonant and non‐resonant off‐diagonal contributions to the momentum flux is emphasized, and collisionless momentum exchange between waves and...... contributes significantly to the residual stress. A general equation for mean κ∥(〈κ∥〉) is derived and used to develop a generalized theory of symmetry breaking. The resonant particle momentum flux is calculated, and pinch and residual stress effects are identified. The implications of the theory for intrinsic...

  2. Generation of electromagnetic structures via modulational instability of drift waves

    International Nuclear Information System (INIS)

    Generation mechanism for large scale electromagnetic structures (blobs) is considered by employing the technique of four-wave interactions (modulational instability). It is shown that primary electrostatic turbulence may generate elongated electromagnetic structures with poloidal modulations. Such structures are principally related to drift-Alfven waves. The analysis fully takes into account finite ion temperature effects and associated diamagnetic contributions to Reynolds stress. The turbulent generation of blobs has instability growth rates which scale similar to the zonal flow instabilities, γ∼, where q is a characteristic wave vector of large scale modes, and V-tilde is a characteristic amplitude of the velocity of turbulent fluctuations. This analysis is shown to be fully consistent with results of an earlier analysis by using the wave kinetic equation.

  3. Shock drift acceleration in the presence of waves

    Science.gov (United States)

    Decker, R. B.; Vlahos, L.

    1985-01-01

    Attention is given to the initial results of a model designed to study the modification of the scatter-free, shock drift acceleration of energetic test particles by wave activity in the vicinity of a quasi-perpendicular, fast-mode MHD shock. It is emphasized that the concept of magnetic moment conservation is a valid approximation only in the perpendicular and nearly perpendicular regimes, when the angle theta-Bn between the shock normal and the upstream magnetic field vector is in the range from 70 deg to 90 deg. The present investigation is concerned with one step in a program which is being developed to combine the shock drift and diffusive processes at a shock of arbitrary theta-Bn.

  4. Light-Gradient-Induced Spiral Wave Drifts in a Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ The dynamic behaviour of spiral tip in the light-sensitive Belousov-Zhabotinsky reaction under the influence of an externally applied light gradient was experimentally studied. The gradient causes different drifts for different spiral patterns. The centre of the spiral wave moved toward the region of lower light intensity. The direction of an additional perpendicular drift depended on the chirality of the spiral wave. The dependences of the drifting angle and the drifting velocity on light gradient have been measured.

  5. Nonlinear trapped electron response for drift wave turbulence in tokamaks

    International Nuclear Information System (INIS)

    The nonlinear trapped electron response to drift wave fluctuations is calculated using the coherent approximation to the DIA in action-angle variables appropriate for toroidal geometry. The bounce-averaged nonlinear response to low frequency electrostatic fluctuations is computed. Employing a spectrum of Pearlstein-Berk structure modes satisfying the symmetry of the ballooning representation, the nonlinear terms are evaluated explicitly. Nonlinear effects do not significantly modify the trapped electron response. Quasineutrality and the nonlinear ion response can then be used in a sheared slab to obtain the turbulence level at saturation level. The level of trapped electron diffusion is calculated

  6. Dust gravitational drift wave in complex plasma under gravity

    International Nuclear Information System (INIS)

    The dispersion relation of electrostatic waves in a complex plasma under gravity is presented. It is assumed that the waves propagate parallel to the external fields. The effects of weak electric field, neutral drag force, and ion drag force are also taken into account. The dispersion relation is numerically examined in an appropriate parameter space in which the gravity plays the dominant role in the dynamics of microparticles. The numerical results show that, in the low pressure complex plasma under gravity, a low frequency drift wave can be developed in the long wavelength limit. The stability state of this wave is switched at a certain critical wavenumber in such a way that the damped mode is transformed into a growing one. Furthermore, the influence of the external fields on the dispersion properties is analyzed. It is shown that the wave instability is essentially due to the electrostatic streaming of plasma particles. It is also found that by increasing the electric field strength, the stability switching occurs at smaller wavenumbers

  7. Coherent structures and transport in drift wave plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Bang Korsholm, S.

    2011-12-15

    Fusion energy research aims at developing fusion power plants providing safe and clean energy with abundant fuels. Plasma turbulence induced transport of energy and particles is a performance limiting factor for fusion devices. Hence the understanding of plasma turbulence is important for optimization. The present work is a part of the puzzle to understand the basic physics of transport induced by drift wave turbulence in the edge region of a plasma. The basis for the study is the Hasegawa-Wakatani model. Simulation results for 3D periodic and nonperiodic geometries are presented. The Hasegawa-Wakatani model is further expanded to include ion temperature effects. Another expansion of the model is derived from the Braginskii electron temperature equation. The result is a self-consistent set of equations describing the dynamical evolution of the drift wave fluctuations of the electron density, electron temperature and the potential in the presence of density and temperature gradients. 3D simulation results of the models are presented. Finally, the construction and first results from the MAST fluctuation reflectometer is described. The results demonstrate how L- to H-mode transitions as well as edge-localized-modes can be detected by the relatively simple diagnostic system. The present Risoe report is a slightly updated version of my original PhD report which was submitted in April 2002 and defended in August 2002. (Author)

  8. Coherent structures and transport in drift wave plasma turbulence

    International Nuclear Information System (INIS)

    Fusion energy research aims at developing fusion power plants providing safe and clean energy with abundant fuels. Plasma turbulence induced transport of energy and particles is a performance limiting factor for fusion devices. Hence the understanding of plasma turbulence is important for optimization. The present work is a part of the puzzle to understand the basic physics of transport induced by drift wave turbulence in the edge region of a plasma. The basis for the study is the Hasegawa-Wakatani model. Simulation results for 3D periodic and nonperiodic geometries are presented. The Hasegawa-Wakatani model is further expanded to include ion temperature effects. Another expansion of the model is derived from the Braginskii electron temperature equation. The result is a self-consistent set of equations describing the dynamical evolution of the drift wave fluctuations of the electron density, electron temperature and the potential in the presence of density and temperature gradients. 3D simulation results of the models are presented. Finally, the construction and first results from the MAST fluctuation reflectometer is described. The results demonstrate how L- to H-mode transitions as well as edge-localized-modes can be detected by the relatively simple diagnostic system. The present Risoe report is a slightly updated version of my original PhD report which was submitted in April 2002 and defended in August 2002. (Author)

  9. Dynamics of zonal flows and self-regulating drift-wave turbulence

    International Nuclear Information System (INIS)

    We present a theory of zonal flow - drift wave dynamics. Zonal flows are generated by modulational instability of a drift wave spectrum, and are damped by collisions. Drift waves undergo random shearing-induced refraction, resulting in increased mean square radial wavenumber. Drift waves and zonal flows together form a simple dynamical system, which has a single stable fixed point. In this state, the fluctuation intensity and turbulent diffusivity are ultimately proportional to the collisional zonal flow damping. The implications of these results for transport models is discussed. (author)

  10. Design of a self-triggered liquid xenon drift chamber for double-beta decay experiments

    International Nuclear Information System (INIS)

    Nuclear double-beta decay is one of the rarest processes in nature with the half life of 1019 - 1024 years. Such process takes place only when a nucleus cannot undergo ordinary beta decay due to energy conservation, or the very strong suppression of energetically allowed transition exists. This process proceeds through the channels of standard second order weak decay (two neutrinos double-beta decay) and lepton number nonconserving, neutrinoless double-beta decay. An isotope of 136Xe possesses attractive properties for the studies on the nuclei subjected to nutrinoless mode. Gaseous or liquid xenon is an excellent working medium for drift chambers, and it can act as both source and detector providing so called active source technique of experiment. In order to search for the neutrinoless mode of 136Xe, the liquid xenon drift chamber was designed, which is composed of three electrodes and four photomultipliers. This drift chamber is described. Th gas handling and vacuum system consisting of a xenon gas purifier, a high vacuum pumping facility and gas storage reservoirs is explained. Event identification, charge division method, the estimation of signal rate and the present state of this study are reported. (K.I.)

  11. Drift-wave spectra in plasmas with magnetic shear

    International Nuclear Information System (INIS)

    The nonlinear radial eigenmode equation governing the evolution of drift waves in a weakly turbulent state is obtained under the assumption that ion nonlinear scattering (nonlinear ion Landau damping) is the dominant saturation mechanism. The poloidal spectrum is to be derived from the eigenvalue equation. The local character of the interaction in frequencies allows the transformation of the otherwise integral wave kinetic equation (i.e., the eigenvalue equation) into a system of two first-order differential equations coupling the spectra I(k/sub theta/) and I(k/sup dagger//sub theta/) if ω(k/sup dagger//sub theta/) = ω(k/sub theta/). The density fluctuation spectrum is obtained analytically in the limit of the small temperature ratio T/sub i//T/sub e/. Some features are: (i) the spectral index at high mode numbers agrees well with experimental values; (ii) the long-wavelength spectrum peaks at k/sub theta/a/sub s/approx. =0.62 (a/sub s/ equivalentsound Larmor radius), (iii) the cross-field diffusion is mostly induced by the high-mode-number fluctuations, whereas the major contribution to the density fluctuations is in the long wavelengths; (iv) the frequency spectrum of the beat waves peaks at ω = 0 (they then have a convective cell character); and (v) the turbulence level is a factor L/sub n//L/sub s/ (ratio of density and shear lengths) smaller than with former theories

  12. Properties of drift waves in a filamentary density depletion

    International Nuclear Information System (INIS)

    This analytical and numerical study explores the properties of electrostatic, drift-wave eigenmodes trapped within a magnetic field-aligned depletion in plasma density and temperature whose transverse dimension is on the order of the electron skin depth. The dependence of the complex eigenfrequencies on key parameters is investigated for collisionless and collisional plasma. The collisional description is based on the Lorentz model of electron pitch-angle scattering. The separate roles of the gradients in density and temperature are illustrated for the collisional and collisionless regimes. The predictions are compared to experimental observations [J. E. Maggs and G. J. Morales, Geophys. Res. Lett. 23, 633 (1996); Phys. Plasmas 4, 290 (1997)] of a controlled striation in the laboratory. copyright 1997 American Institute of Physics

  13. Formation of convective cells by modulational instability of drift Alfven waves

    International Nuclear Information System (INIS)

    A model equation describing drift Alfven wave with E X B nonlinearity is derived. For a special ordering a nonlinear Schroedinger equation is derived, which governs modulational instability of the drift Alfven wave. Translational invariance is assumed along the magnetic field. The relation between the characteristic scale lengths parallel and perpendicular to the drift flow for the onset of cell formation has been found. The influence of perpendicular ion viscosity is also discussed. (Auth.)

  14. Drift wave transport and origin of the disruption phenomenon

    International Nuclear Information System (INIS)

    Nonlinear ion Landau damping of drift waves yields a splitting of the spectrum into a long and a short wavelength branch. The latter contributes most (> 90%) of the transport and permits to explain the observed relaxation of Tokamak plasma profiles to a weakly unstable state, in the occurence with regard to the dissipative trapped electron mode. The fluxes indeed increase much more rapidly than the linear growth rates. This result and surprising coincidences between the linear theory and empirical laws concerning the high density limit lead us to propose that the slow rise of the sawtooth pulsations of the core occurs whilst the transport in the surrounding layer is insufficient to evacuate the power deposited. The sudden relaxation takes place once the released heat pulses are capable - much as in collisionless shock waves - of exciting the trapped electron mode to a sufficient level to ensure adequate transport. The model explains many experimental features associated with these sawteeth as well as with the related plasma disruptions: contraction of the current channel, high density limit (both the scaling and the order of magnitude are predicted), etc. ... (orig.)

  15. Drift-Kinetic Alfven Waves Observed near a Reconnection X Line in the Earth's Magnetopause

    International Nuclear Information System (INIS)

    We identify drift-kinetic Alfven waves in the vicinity of a reconnection X line on the Earth's magnetopause. The dispersive properties of these waves have been determined using wavelet interferometric techniques applied to multipoint observations from the Cluster spacecraft. Comparison of the observed wave dispersion with that expected for drift-kinetic Alfven waves shows close agreement. The waves propagate outwards from the X line suggesting that reconnection is a kinetic Alfven wave source. Energetic O+ ions observed in these waves indicate that reconnection is a driver of auroral ion outflow

  16. Physical mechanism behind zonal-flow generation in drift-wave turbulence.

    Science.gov (United States)

    Manz, P; Ramisch, M; Stroth, U

    2009-10-16

    The energetic interaction between drift-wave turbulence and zonal flows is studied experimentally in two-dimensional wave number space. The kinetic energy is found to be transferred nonlocally from the drift waves to the zonal flow. This confirms the theoretical prediction that the parametric-modulational instability is the driving mechanism of zonal flows. The physical mechanism of this nonlocal energetic interaction between and zonal flows and turbulent drift-wave eddies in relation to the suppression of turbulent transport is discussed. PMID:19905704

  17. Effect of a Dissipative Term in the Drift Waves Hamiltonian System

    CERN Document Server

    Oyarzabal, Ricardo S; Batista, Antonio M; Caldas, Iberê L; Viana, Ricardo L; Iarosz, Kelly C

    2015-01-01

    This paper analyses the Hamiltonian model of drift waves which describes the chaotic transport of particles in the plasma confinement. With one drift wave the system is integrable and it presents stable orbits. When one wave is added the system may or may not be integrable depending on the phase of each wave velocity. If the two waves have the same phase velocity, the system is integrable. When the phase velocities between the two waves are different, the system shows chaotic behaviour. In this model we add a small dissipation. In the presence of a weak dissipation, for different initial conditions, we observe transient orbits which converge to periodic attractors.

  18. Statistical theory of resistive drift-wave turbulence and transport

    International Nuclear Information System (INIS)

    Resistive drift-wave turbulence in a slab geometry is studied by statistical closure methods and direct numerical simulations. The two-field Hasegawa endash Wakatani (HW) fluid model, which evolves the electrostatic potential and plasma density self-consistently, is a paradigm for understanding the generic nonlinear behavior of multiple-field plasma turbulence. A gyrokinetic derivation of the HW model is sketched. The recently developed Realizable Markovian Closure (RMC) is applied to the HW model; spectral properties, nonlinear energy transfers, and turbulent transport calculations are discussed. The closure results are also compared to direct numerical simulation results; excellent agreement is found. The transport scaling with the adiabaticity parameter, which measures the strength of the parallel electron resistivity, is analytically derived and understood through weak- and strong-turbulence analyses. No evidence is found to support previous suggestions that coherent structures cause a large depression of saturated transport from its quasilinear value in the hydrodynamic regime of the HW model. Instead, the depression of transport is well explained by the spectral balance equation of the (second-order) statistical closure when account is taken of incoherent noise. copyright 1997 American Institute of Physics

  19. Destabilization of hydromagnetic drift-Alfven waves in a finite pressure, collisional plasma

    International Nuclear Information System (INIS)

    The hydromagnetic drift mode of the coupled drift-Alfven wave is destabilized as a standing wave in a dense, current-free plasma in the presence of a density gradient. When an axial electron current is drawn, a localized Alfven mode propagating against the current is destabilized, in addition to the unstable drift mode now propagating along the current. The measured wave properties, dispersion, and dependence on plasma parameters are found to agree with the theory derived for a finite β, collisional plasma

  20. Comparison of drift wave models with fluctuation data from the interior of the TEXT tokamak

    International Nuclear Information System (INIS)

    Experimental evidence for and against drift waves as the origin of the observed fluctuations and anomalous transport in the plasma interior is reviewed. Fluctuation spectra observed by far-infrared scattering and a heavy ion beam probe (HIBP) are compared. The FIR system observes broad S(k,ω), which are spatially resolved at large k and readily identified with electron drift waves. At higher densities a clear feature, which may be associated with ion temperature gradient modes, appears as well. A quasi-coherent feature in the drift wave range of phase velocities is also found at the inner mid-plane. But interior HIBP measurements using a thallium beam have, by a two-point correlation method, measured wave numbers far too small to be those of drift waves of either variety. Some recent measurements with a cesium beam have produced phase velocities more closely in accord with drift waves at low frequencies. It is suggested that a new mode may be present, which is not drift waves at low frequencies. It is suggested that a new mode may be present, which is not drift wave-like. However, the phase velocity and coherence of the HIBP data exhibit qualitative features that suggest possible instrumental effects. Several of these are investigated, which individually do not appear to reconcile the data with a pure drift wave model. They are sample volume size, common mode effects such as cross talk or path integrals of beam attenuation, and two-stream instabilities. Reconciliation of these measurements is important to transport studies. That is, calculated particle and energy fluxes depend sensitively on the frequency and wave number spectrum employed. The theoretical considerations about two-point correlations and possible instrumental effects are also relevant to other diagnostics using this technique

  1. Spatial mode structures of electrostatic drift waves in a collisional cylindrical helicon plasma

    DEFF Research Database (Denmark)

    Schröder, C.; Grulke, O.; Klinger, T.;

    2004-01-01

    In a cylindrical helicon plasma, mode structures of coherent drift waves are studied in the poloidal plane, the plane perpendicular to the ambient magnetic field. The mode structures rotate with a constant angular velocity in the direction of the electron diamagnetic drift and show significant...

  2. Transport driven by G modes and resistive drift waves based on scale invariance

    International Nuclear Information System (INIS)

    Scale transformation introduced by Connor and Taylor is applied to the model equations for the resistive interchange mode (g mode) and the resistive drift wave in a high shear helical system. The electron pressure gradient term in Ohm's law is essential in deriving the present results. Scaling of collisionless transport along stochastic fields due to the g modes coincides with the result based on the mixing length theory. When the resistive drift waves are dominant, the predicted transport is κ2/s2 times the pseudo-classical transport, where κ is the characteristic length of density gradient and s is the shear parameter. The transport coefficient which results from the g mode and/or the resistive drift wave turbulence increases towards the edge. The density fluctuation for the resistive drift wave turbulence scales as (Te/n)1/2κ which also increases toward the edge in most toroidal plasmas. (author)

  3. Drift kinetic Alfvén wave in temperature anisotropic plasma

    International Nuclear Information System (INIS)

    By using the gyrokinetic theory, the kinetic Alfvén waves (KAWs) are discussed to emphasize the drift effects through the density inhomogeneity and the temperature anisotropy on their dispersion characteristics. The dependence of stabilization mechanism of the drift-Alfvén wave instability on the temperature anisotropy is highlighted. The estimate of the growth rate and the threshold condition for a wide range of parameters are also discussed

  4. Analysis of zonal flow bifurcations in 3D drift wave turbulence simulations

    International Nuclear Information System (INIS)

    The main issue of experimental magnetic fusion devices lies with their inherently high turbulent transport, preventing long-term plasma confinement. A deeper understanding of the underlying transport processes is therefore desirable, especially in the high-gradient tokamak edge which marks the location of the drift wave regime as well as the outer boundary of the still badly understood high confinement mode. One of the most promising plasma features possibly connected to a complete bifurcation theory for the transition to this H-mode is found in large-scale phenomena capable of regulating radial transport through vortex shearing - i.e. zonal flows, linearly stable large-scale poloidal vector E x vector B-modes based on radial flux surface averages of the potential gradient generated through turbulent self-organization. Despite their relevance, few detailed turbulence studies of drift wave-based zonal flows have been undertaken, and none of them have explicitly targeted bifurcations - or, within a resistive sheared-slab environment, observed zonal flows at all. In this work, both analytical means and the two-fluid code NLET are used to analyze a reduced set of Hasegawa-Wakatani equations, describing a sheared collisional drift wave system without curvature. The characteristics of the drift waves themselves, as well as those of the drift wave-based zonal flows and their retroaction on the drift wave turbulence are examined. The single dimensionless parameter ρs proposed in previous analytical models is examined numerically and shown to divide the drift wave scale into two transport regimes, the behavioral characteristics of which agree perfectly with theoretical expectations. This transport transition correlates with a transition from pure drift wave turbulence at low ρs into the high-ρs zonal flow regime. The associated threshold has been more clearly identified by tracing it back to a tipping of the ratio between a newly proposed frequency gradient length at the

  5. Theoretical studies of coherent nonlinear drift wave-zonal flow interactions

    International Nuclear Information System (INIS)

    Full text: We have, employing a slab model, carried out in-depth theoretical studies on the coherent nonlinear interactions between drift waves (DW) and zonal flows (ZF). In this talk, we will first review the four-wave modulational mechanism for the spontaneous excitation of zonal flow by coherent drift waves. As the amplitude of the primary (pump) drift wave attains spatial localization due to plasma non-uniformities and/or initial localized perturbations, the excited zonal flows become localized structures; leading to cascading of drift waves toward shorter (radial) wave numbers.This nonlinearly generated normal cascading and accompanied enhanced (radial) dispersiveness leads to the new novel result that, time asymptotically, coherent drift waves can be trapped by the self-induced zonal flows; similar to the Langmuir wave-density cavity soliton physics. Indeed, both analytical theories and direct numerical calculations demonstrate the formation and, consequently, radial propagation of DW-ZF solitary structures. Additional effects such as linear growth, dissipations, equilibrium non-uniformities and soliton dynamics could further lead to interesting physics; e.g., generation, destruction, collision, and reflection of solitons, as well as turbulence bursting. The propagation of DW-ZF solitons causes significant radial spreading of DW turbulence and ,hence, could qualitatively modify the transport processes. Generalization to the toroidal geometries will also be presented. Research supported by U.S. DoE. (author)

  6. Measurement of coherent drift-wave ion-fluid velocity field when ion dynamics are stochastic

    International Nuclear Information System (INIS)

    In order to test the validity of the fluid drift approximation when ion dynamics are stochastic, the time-dependent ion-fluid velocity field in a coherent, drift-Alfven wave has been measured in Caltech's Encore tokamak using plasma planar laser induced fluorescence. Many measured parameters of the wave are well described by the drift approximation above a threshold for stochastic ion dynamics, including the flow pattern in the single measured component of the ion-fluid velocity field. Surprisingly, the theory fails at a fundamental level by predicting flow speeds 10 times larger than those measured (|umax|∼105 cm/s)

  7. Effects of Periodic Forcing Amplitude on the Spiral Wave Resonance Drift

    Institute of Scientific and Technical Information of China (English)

    WU Ning-Jie; LI Bing-Wei; YING He-Ping

    2006-01-01

    @@ We study dynamics of spiral waves under a uniform periodic temporal forcing in an excitable medium. With a specific combination of frequency and amplitude of the external periodic forcing, a resonance drift of a spiral wave occurs along a straight line, and it is accompanied by a complicated ‘flower-like’ motion on each side of this bifurcate boundary line. It is confirmed that the straight-line drift frequency of spiral waves is not locked to the nature rotation frequency as the forcing amplitude expends the range of the spiral wave frequency. These results are further verified numerically for a simplified kinematical model.

  8. Stochastic electron dynamics due to drift waves in a sheared magnetic field and other drift motion problems

    International Nuclear Information System (INIS)

    Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochasticity occurs for low parallel velocity electrons for which the parallel trapping motion from eE/sub parallel//m interacts strongly with the E x B trapping motion due to the presence of magnetic shear. The guiding-center equations for single particle electron orbits in given fields are investigated using both analytical and numerical techniques. The model assumes a slab magnetic field geometry with shear and two electrostatic plane waves propagating at an angle with respect to each other. Collisions and the self-consistent effect of the electron motion upon the fields are ignored. The guiding-center motion in an inertial reference frame moving in phase with the two waves is given by a two degree-of-freedom, autonomous Hamiltonian system. The single wave particle motion may be reduced to a two parameter family of one degree-of-freedom Hamiltonians which bifurcate from a pendulum phase space to a topology with three chains of elliptic and hyperbolic fixed points separated in radius about the mode-rational surface. In the presence of a perturbing wave with a different helicity, electrons in the small parallel velocity regime become stochastic at an amplitude scaling as the fourth root of the wave potential. The results obtained for stochastic motion apply directly to the problem of electron diffusion in drift waves occurring in toroidal fusion confinement devices. The effect of an adiabatically changing radial electric field upon guiding-center orbits in tokamaks is also investigated. This perturbation causes a radial polarization drift of trapped particle tokamak orbits

  9. Nonlinear drift wave instability due to nonlinear structures

    International Nuclear Information System (INIS)

    A nonlinear instability due to zonal flows and magnetic islands has been found. The instability has the character of a dissipative drift instability due to an anomalous resistivity. The anomalous resistivity is typically two orders of magnitude larger than the classical at the edge. (author)

  10. Thermal-wave balancing flow sensor with low-drift power feedback

    International Nuclear Information System (INIS)

    A control system using a low-drift power-feedback signal was implemented applying thermal waves, giving a sensor output independent of resistance drift and thermo-electric offset voltages on interface wires. Kelvin-contact sensing and power control is used on heater resistors, thereby inhibiting the influence of heater resistance drift. The thermal waves are detected with a sensing resistor using a lock-in amplifier and are mutually cancelled by a thermal-wave balancing controller. Offset due to thermal gradient across the chip and resistor drift are eliminated by the lock-in amplifier and power controller, and therefore do not influence the sensor output signal. A microchannel thermal-wave balancing flow sensor with integrated Al resistors has successfully been fabricated. The thermal flow sensor is capable of measuring water flow rates with nl ⋅ min−1 precision, up to about 500 nl ⋅ min−1 full scale. Measurement results are in good agreement with a dynamic model of the flow sensor. Drift measurements show the sensor output signal to be compensated for resistance drift and thermal gradient across the chip. (paper)

  11. Experimental investigation of the nonlinear evolution of an impurity-driven drift wave

    International Nuclear Information System (INIS)

    An impurity-driven drift wave is observed to be destabilized by the reversed density gradient of a singly-ionized heavy-impurity-ion population in a Q-machine plasma. The evolution of the instability is investigated as it progresses from the initial linear exponential growth phase, into a nonlinear saturated state, whereupon strong radially outward anomalous diffusion is observed. The relationship between the anomalous diffusion coefficient and the wave amplitude is in agreement with estimates obtained from the nonlinear drift-wave turbulence theory of Dupree

  12. Ion waves generated by ion loss-cone distributions or drifting particles

    International Nuclear Information System (INIS)

    Electrostatic ion waves may be generated by ion loss-cone distributions, even when cool electrons are present. Although the propagation and stability properties of these waves are well described by a dispersion relation obtained in the electrostatic approximation, they may have a significant wave magnetic field. The emissions may be resonant or non-resonant in nature, and can occur between multiples of the gyrofrequencies of the ion species in the plasma, or as broadband waves near the lower hybrid frequency. Alfven waves may also be destabilized by ion loss-cone distributions. The ratio of the electric and magnetic fields of these waves is not always equal to the Alfven speed. These theoretical considerations are favourably compared with observations by the GEOS satellites of ion loss-cone distributions and ion waves. Particles drifting along the ambient magnetic field may generate ion waves, but knowledge of the current density only is not sufficient to determine the stability of these waves. The importance of non-drifting particle distributions which may damp the waves and the destabilizing effects of drifting, low-density particle components are discussed in connection with current structures observed by the GEOS spacecraft. (Author)

  13. Secondary instability in drift wave turbulence as a mechanism for avalanche and zonal flow formation

    International Nuclear Information System (INIS)

    We report on recent developments in the theory of secondary instability in drift-ITG turbulence. Specifically, we explore secondary instability as a mechanism for avalanche formation. A theory of radially extended streamer cell formation and self-regulation is presented. Aspects of streamer structure and dynamics are used to estimate the variance of the drift-wave induced flux. The relation between streamer cell structures and the avalanche concept is discussed, as are the implications of our results for transport modeling. (author)

  14. Filament tension and phase-locked drift of meandering scroll waves

    OpenAIRE

    Dierckx, Hans; Biktasheva, Irina V.; Verschelde, Henri; Panfilov, Alexander V.; Biktashev, Vadim N.

    2016-01-01

    Rotating scroll waves are self-organising patterns which are found in many oscillating or excitable systems. Here we show that quasi-periodic (meandering) scroll waves, which include the rotors that organise cardiac arrhythmias, exhibit filament tension when averaged over the meander cycle. With strong filament curvature or medium thickness gradients, however, scroll wave dynamics are governed by phase-locked drift instead of filament tension. Our results are validated in computational models...

  15. Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Misra, A. P., E-mail: apmisra@visva-bharati.ac.in, E-mail: apmisra@gmail.com [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India)

    2014-04-15

    We study the amplitude modulation of low-frequency, long-wavelength electrostatic drift-wave envelopes in a nonuniform quantum magnetoplasma consisting of cold ions and degenerate electrons. The effects of tunneling associated with the quantum Bohm potential and the Fermi pressure for nonrelativistic degenerate electrons, as well as the equilibrium density and magnetic field inhomogeneities are taken into account. Starting from a set of quantum magnetohydrodynamic equations, we derive a nonlinear Schrödinger equation (NLSE) that governs the dynamics of the modulated quantum drift-wave packets. The NLSE is used to study the modulational instability (MI) of a Stoke's wave train to a small plane wave perturbation. It is shown that the quantum tunneling effect as well as the scale length of inhomogeneity plays crucial roles for the MI of the drift-wave packets. Thus, the latter can propagate in the form of bright and dark envelope solitons or as drift-wave rogons in degenerate dense magnetoplasmas.

  16. The effect of plasma shear flow on drift Alfven instabilities of a finite beta plasma and on anomalous heating of ions by ion cyclotron turbulence

    Science.gov (United States)

    Jo, Young Hyun; Lee, Hae June; Mikhailenko, Vladimir V.; Mikhailenko, Vladimir S.

    2016-01-01

    It was derived that the drift-Alfven instabilities with the shear flow parallel to the magnetic field have significant difference from the drift-Alfven instabilities of a shearless plasma when the ion temperature is comparable with electron temperature for a finite plasma beta. The velocity shear not only modifies the frequency and the growth rate of the known drift-Alfven instability, which develops due to the inverse electron Landau damping, but also triggers a combined effect of the velocity shear and the inverse ion Landau damping, which manifests the development of the ion kinetic shear-flow-driven drift-Alfven instability. The excited unstable waves have the phase velocities along the magnetic field comparable with the ion thermal velocity, and the growth rate is comparable with the frequency. The development of this instability may be the efficient mechanism of the ion energization in shear flows. The levels of the drift--Alfven turbulence, resulted from the development of both instabilities, are determined from the renormalized nonlinear dispersion equation, which accounts for the nonlinear effect of the scattering of ions by the electromagnetic turbulence. The renormalized quasilinear equation for the ion distribution function, which accounts for the same effect of the scattering of ions by electromagnetic turbulence, is derived and employed for the analysis of the ion viscosity and ions heating, resulted from the interactions of ions with drift-Alfven turbulence. In the same way, the phenomena of the ion cyclotron turbulence and anomalous anisotropic heating of ions by ion cyclotron plasma turbulence has numerous practical applications in physics of the near-Earth space plasmas. Using the methodology of the shearing modes, the kinetic theory of the ion cyclotron turbulence of the plasma with transverse current with strong velocity shear has been developed.

  17. Negative viscosity and generation of dissipative solitons and zonal dissipative structures by drift waves

    International Nuclear Information System (INIS)

    In this paper the stability of a drift wave in a plasma with dissipation due to ion viscosity is examined. If the wave amplitude exceeds a threshold value, determined by ion--ion collisions, large-scale perturbations (i.e., with scales much greater than the drift wavelength) grow. Maximum growth rate belongs to perturbations that are periodical along plasma inhomogeneity and constant in transverse directions, i.e., azimuthal direction in cylindrical geometry (zonal dissipative structures). The analysis of nonlinear stage of large-scale instability shows that the solitonlike large-scale structures of the electric field and vorticity are possible (dissipative solitons)

  18. Ponderomotive force of the low-frequency field and modulational instability of drift waves

    International Nuclear Information System (INIS)

    A study is made of the processes that occur in an inhomogeneous nonisothermal plasma in a strong external magnetic field and whose characteristic frequencies are lower than the ion Langmuir frequency but higher than the collision frequency. An expression for the ponderomotive force of the low-frequency field is derived. The excitation of a long-wavelength low-frequency drift wave during the development of the modulational instability of a drift pump wave is investigated. The growth rates of the instability are obtained, and the conditions for its onset are determined. The possible relation of the modulational instability to the formation of structures in the plasma is discussed

  19. Lattice Boltzmann model for collisionless electrostatic drift wave turbulence obeying Charney-Hasegawa-Mima dynamics

    CERN Document Server

    Held, M

    2015-01-01

    A lattice Boltzmann method (LBM) approach to the Charney-Hasegawa-Mima (CHM) model for adiabatic drift wave turbulence in magnetised plasmas, is implemented. The CHM-LBM model contains a barotropic equation of state for the potential, a force term including a cross-product analogous to the Coriolis force in quasigeostrophic models, and a density gradient source term. Expansion of the resulting lattice Boltzmann model equations leads to cold-ion fluid continuity and momentum equations, which resemble CHM dynamics under drift ordering. The resulting numerical solutions of standard test cases (monopole propagation, stable drift modes and decaying turbulence) are compared to results obtained by a conventional finite difference scheme that directly discretizes the CHM equation. The LB scheme resembles characteristic CHM dynamics apart from an additional shear in the density gradient direction. The occuring shear reduces with the drift ratio and is ascribed to the compressible limit of the underlying LBM.

  20. Discrete exact and quasi-resonances of Rossby/drift waves on $\\b$-plane with periodic boundary conditions

    CERN Document Server

    Kartashov, A

    2013-01-01

    Analysis of resonance clustering in weakly nonlinear dispersive wave systems, also called discrete wave turbulent systems, is a new methodology successfully used in the last years for characterizing energy transport due to exact and quasi-resonances. Quite recently this methodology has been used in the paper by M. D. Bustamante, U. Hayat "Complete classification of discrete resonant Rossby/drift wave triads on periodic domains", \\cite{BH13}, in order to show that resonance clustering is very sparse and quasi-resonances (that is, resonances with small enough detuning) play major role in the energy transport in this specific wave system. On the other hand, in the paper by M. Yamada, T. Yoneda "Resonant interaction of Rossby waves in two-dimensional flow on $\\beta$-plane", \\cite{YaYo13}, the same physical system is studied and a mathematically rigorous theorem is proven: at high $\\b$, the flow dynamics is governed exclusively by resonant interactions. In our present paper we demonstrate that this seeming contrad...

  1. Models for electrostatic drift waves with density variations along magnetic field lines

    Science.gov (United States)

    Garcia, O. E.; Pécseli, H. L.

    2013-11-01

    Drift waves with vertical magnetic fields in gravitational ionospheres are considered where the unperturbed plasma density is enhanced in a magnetic flux tube. The gravitational field gives rise to an overall decrease of plasma density for increasing altitude. Simple models predict that drift waves with finite vertical wave vector components can increase in amplitude merely due to a conservation of energy density flux of the waves. Field-aligned currents are some of the mechanisms that can give rise to fluctuations that are truly unstable. We suggest a self-consistent generator or "battery" mechanism that in the polar ionospheres can give rise to magnetic field-aligned currents even in the absence of electron precipitation. The free energy here is supplied by steady state electric fields imposed in the direction perpendicular to the magnetic field in the collisional lower parts of the ionosphere or by neutral winds that have similar effects.

  2. High harmonic fast waves in high beta plasmas

    International Nuclear Information System (INIS)

    High harmonic fast magnetosonic wave in high beta/high dielectric plasmas is investigated. including the finite-Larmor-radius effects. In this regime, due to the combination of group velocity slow down and the high beta enhancement, the electron absorption via electron Landau and electron magnetic pumping becomes significant enough that one can expect a strong (∼ 100%) single pass absorption. By controlling the wave spectrum, the prospect of some localized electron heating and current drive appears to be feasible in high beta low-aspect-ratio tokamak regimes. Inclusion of finite-Larmor-radius terms shows an accessibility limit in the high ion beta regime (βi = 50% for a deuterium plasma) due to mode-conversion into an ion Bernstein-wave-like mode while no beta limit is expected for electrons. With increasing ion beta, the ion damping can increase significantly particularly near the beta limits. The presence of energetic ion component expected during intense NBI and α-heating does not appear to modify the accessibility condition nor cause excessive wave absorption

  3. Drift wave shear damping annulment due to parametric coupling and magnetic field variation

    International Nuclear Information System (INIS)

    Nonlinear suppression of the drift wave shear damping by the simultaneous action of a strong standing pump wave and of the magnetic field variation along the magnetic field line is studied using a version of the Hasegawa-Mima equation. The threshold for the parametric destabilization is calculated as a function of the plasma parameters. Destabilization occurs due to the elimination of the energy convection towards the dissipative layer, by both the linear toroidal coupling and nonlinear parametric coupling

  4. Theory of particle and energy flux from the magnetic flutter of drift waves

    International Nuclear Information System (INIS)

    A quasi-linear theory of particle and energy flux by magnetic flutter associated with drift waves is presented. It is shown that magnetic flutter can enhance the energy flux. However, particle diffusion is ambipolar and runaway electrons do not escape along the field lines

  5. Dust magneto-gravitational drift wave in g×B configuration

    International Nuclear Information System (INIS)

    The dispersion relation of electrostatic waves in a magnetized complex plasma under gravity is presented. It is assumed that the waves propagate perpendicular to the external fields. The effects of weak electric field, neutral drag force, and ion drag force are also taken into account. The dispersion relation is numerically examined in an appropriate parameter space in which the gravity plays the dominant role in the dynamics of magnetized microparticles. The numerical results show that an unstable low frequency drift wave can be developed in the long wavelength limit. This unstable mode is transformed into an aperiodic stationary structure at a cut-off wavenumber. Furthermore, the influence of the external fields on the dispersion properties is analyzed. It is shown that the instability is essentially due to the E×B drift motion of plasma particles. However, in the absence of weak electric field, the g×B drift motion of microparticles can cause the instability in a wide range of wavenumbers. It is also found that by increasing the magnetic field strength, the wave frequency is first increased and then decreased. This behaviour is explained by the existence of an extremum point in the dust magneto-gravitational drift velocity

  6. The Entropy and Complexity of Drift waves in a LAPTAG Plasma Physics Experiment

    Science.gov (United States)

    Birge-Lee, Henry; Gekelman, Walter; Pribyl, Patrick; Wise, Joe; Katz, Cami; Baker, Bob; Marmie, Ken; Thomas, Sam; Buckley-Bonnano, Samuel

    2015-11-01

    Drift waves grow from noise on a density gradient in a narrow (dia = 3 cm, L = 1.5 m) magnetized (Boz = 160G) plasma column. A two-dimensional probe drive measured fluctuations in the plasma column in a plane transverse to the background magnetic field. Correlation techniques determined that the fluctuations were that of electrostatic drift waves. The time series data was used to generate the Bandt-Pompe/Shannon entropy, H, and Jensen-Shannon complexity, CJS. C-H diagrams can be used to tell the difference between deterministic chaos, random noise and stochastic processes and simple waves, which makes it a powerful tool in nonlinear dynamics. The C-H diagram in this experiment, reveal that the combination of drift waves and other background fluctuations is a deterministically chaotic system. The PDF of the time series, the wave spectra the spatial dependence of the entropy wave complexity will be presented. LAPTAG is a university-high school alliance outreach program, which has been in existence for over 20 years. Work done at BaPSF at UCLA and supported by NSF and DOE.

  7. Experimental quiescent drifting dusty plasmas and temporal dust acoustic wave growth

    International Nuclear Information System (INIS)

    We report on dust acoustic wave growth rate measurements taken in a dc (anode glow) discharge plasma device. By introducing a mesh with a variable bias 12-17 cm from the anode, we developed a technique to produce a drifting dusty plasma. A secondary dust cloud, free of dust acoustic waves, was trapped adjacent to the anode side of the mesh. When the mesh was returned to its floating potential, the secondary cloud was released and streamed towards the anode and primary dust cloud, spontaneously exciting dust acoustic waves. The amplitude growth of the excited dust acoustic waves was measured directly along with the wavelength and Doppler shifted frequency. These measurements were compared to fluid and kinetic dust acoustic wave theories. As the wave growth saturated a transition from linear to nonlinear waves was observed. The merging of the secondary and primary dust clouds was also observed.

  8. Lion roars and nonoscillatory drift mirror waves in the magnetosheath

    International Nuclear Information System (INIS)

    A complete set of ISEE plasma wave, plasma, and field data are used to identify the plasma instability responsible for the generation of extremely low frequency (ELF) electromagnetic lion roars. Lion roars detected close to the magnetopause are generated by the cyclotron instability of anisotropic (T-/sub perpendicular//T-/sub parallel/approx. =1.2) thermal electrons when the local plasma critical energy, E/sub M/ = B2/8πN, falls to values (E/sub M/ approx.10--30 eV) close to or below the electron thermal energy, 25 eV, as a result of decreases in B. The lion roars are terminated by increases in the ambient magnetic field magnitude and consequential increases in E/sub M/ to values greater than 100 eV. Because there are few resonant particles at these high energies, the growth rate decreases by 3 orders of magnitude and measurable growth ceases. The value of the absolute upper limit of the frequency of unstable waves predicted by theory, ω/sub max/ = A-Ω-/(A-+1), is compared with observations. The predictions and observations are found to be in general, but not exact, agreement. Several possible explanations are explored. The quasi-periodic, approx.20-s magnetic and plasma oscillations which cause the variations in E/sub M/ and hence alternately drive the cyclotron waves unstable and then stable are also investigated

  9. Beta Distribution of Surface Elevation of Random Waves

    Institute of Scientific and Technical Information of China (English)

    张军; 徐德伦

    2001-01-01

    A probability density function (PDF) is derived of beta distribution with both λ3 (skewness) and λ4 (kurtosis) as parameters for weakly nonlinear wave surface elevation by use of a method recently proposed by Srokosz. This PDF not only has a simpler form than the well-known Gram-Charlier Series PDF derived by Longuet-Higgins, but also overcomes an obvious shortcoming of the latter that when the series is unsuitably truncated, the resulting PDF is locally negative. To test the derived beta PDF, laboratorial experiments of wind waves are conducted. The experimental data indicate that the theoretical requirements of the parameters in the beta PDF are fulfilled. The experimental results show that the present PDF is in better agreement with the measured data than the beta PDF only including parameter λ3, and also than the Gram-Charlier Series PDF truncated up to the term of H6.

  10. Wave interactions with EBT plasmas in the magnetic drift frequency range

    International Nuclear Information System (INIS)

    We calculate the particle and energy transport and heating that results from the resonant, quasilinear interaction of EBT plasma particles with waves in the magnetic drift frequency range. Substantial transport can occur even for relatively small wave field amplitudes. For example, for flute perturbations of relative amplitude deltaB/B, the wave induced diffusion can exceed neoclassical diffusion in the collisionless regime for deltaB/B approx. (nu/ωdel)/sup 1/2/ A-1, where A-1 is the inverse aspect ratio and nu, ωdel are the collision and thermal grad B drift frequencies, respectively. The diffusion is selective and can cause preferential transport of a single sign of charge or energy component. Possible applications include plasma pressure and ambipolar potential profile modification, instability induced transport arising from curvature or drift modes and α-ash removal. In addition, this type of wave-particle interaction may play a role in the observed changes in EBT-S electron ring parameters during ICH experiments

  11. The nonlinear dynamics of the modulational instability of drift waves and the associated zonal flows

    International Nuclear Information System (INIS)

    The linear and nonlinear dynamics of zonal flows and their interactions with drift wave turbulence is considered in the simple but illuminating generalized Charney-Hasegawa-Mima model due to Smolyakov et al. [Phys. Plasmas 7, 1349 (2000)]. Two positive definite, exact, integral invariants associated with the full generalized Charney-Hasegawa-Mima system are derived. For an initial monochromatic drift wave pump with small but finite amplitude, a modulational instability can occur, characterized by growing zonal flow and sideband perturbations (i.e., a four-wave interaction). The pump threshold for instability is readily satisfied, depending on the zonal flow wave number. The fully nonlinear Charney-Hasegawa-Mima equations are solved with a numerical scheme which is validated by demonstrating the conservation of the two exact invariants. The simulations show that the validity of the four-wave model is limited to approximately three instability growth times. The radial structure of the zonal flow can be 'jet-like' or highly oscillatory depending upon the ratio of the system size to the density scale length and initial conditions. It is found that zonal flows can be dramatically reduced if the most unstable zonal flow wave number does not fit into the system

  12. Convective cell formation and anomalous diffusion due to electromagnetic drift wave turbulence

    International Nuclear Information System (INIS)

    Convective cell formation and spectral cascade processes due to gravitational drift Alfven waves are studied using a new type of model equation. Conservation relations are derived and explosive instability is found for systems near marginal finite β stability. This instability also remains when the effects of poor as well as favorable curvature regions are included, i.e., for ballooning modes. The anomalous diffusion due to convective cells and quasi-linear effects are compared

  13. Complete classification of discrete resonant Rossby/drift wave triads on periodic domains

    CERN Document Server

    Bustamante, Miguel D

    2013-01-01

    We consider the set of Diophantine equations that arise in the context of the barotropic vorticity equation on periodic domains, when nonlinear wave interactions are studied to leading order in the amplitudes. The solutions to this set of Diophantine equations are of interest in atmosphere (Rossby waves) and Tokamak plasmas (drift waves), because they provide the values of the spectral wavevectors that interact resonantly via three-wave interactions. These come in "triads", i.e., groups of three wavevectors. We provide the full solution to the Diophantine equations in the case of infinite Rossby deformation radius. The method is completely new, and relies on mapping the unknown variables to rational points on quadratic forms of "Minkowski" type. Classical methods invented centuries ago by Fermat, Euler, Lagrange and Minkowski, are used to classify all solutions to our original Diophantine equations, thus providing a computational method to generate numerically all the resonant triads in the system. Our method...

  14. The Frequency Drift of the Envelope Solitary Waves Near ωcH+ in Observations of Freja

    OpenAIRE

    Guang-Li, H.; Le Quéau, D.; Wang, De-yu

    1995-01-01

    In this paper, the ion cyclotron envelope solitary waves with a "cigar" shape observed by Freja satellite are reported and studied, especially, the drift of the frequency of the waves is contributed to the non-linear effects on the resonance frequency, which predicts that the frequency drift is directly proportional to the squaire of the amplitude of the oscillations. This result is comparable with the observations of the Freja satellite.

  15. Numerical simulation of drift wave turbulence in fluid models with Landau damping

    International Nuclear Information System (INIS)

    Following the work of Hammett and Perkins, the authors construct a nonlinear electrostatic fluid-like model for collisionless circulating ions and electrons containing Landau damping. Six-field perturbations (density, electric potential, ion and electron parallel velocity, and ion and electron pressure) are advanced in time. Both density and temperature gradients are considered. Polarization drift as well as FLR effects are included and the system may be generalized to include curvature effects. Apart from artificial viscosity at large perpendicular wave numbers, the only dissipative element is a collisionless parallel heat diffusivity (Vth/kparallel) for both ions and electrons. (There is no parallel viscosity.) This corresponds to a three-pole approximation of the plasma dispersion (Z-) function. A similar six-field set can be written for hydrogen and impurity ions with Boltzmann electrons. The equations of motion are encoded in an (m,n,r) representation with a sheared and curved magnetic field. There are several motivations for treating such complex systems. In addition to the ion temperature gradient mode, the electron-ion set contains the universal drift mode which may have nonlinear instability properties similar to the collisional drift wave. Both sets contain mass ratios (Ami/me or Ami/mI, respectively) which may be a key to the mysterious atomic number (A-) scaling in tokamak confinement. Preliminary studies of linear stability of the models in comparison to the true kinetic response are discussed and some initial single helicity nonlinear simulations are presented. 3 refs

  16. Drift wave excitation in the THETA-pinch high pressure plasma

    International Nuclear Information System (INIS)

    Excitation of low-frequency (LF) drift waves has been experimentally investigated in a high-pressure plasma in a gas discharge of the direct THETA-pinch type. The electrodeless inductive gas discharge is produced in an alundum tube of 150 cm length and 6.5 cm internal diameter filled with hydrogen at the pressure of (1-20).10-3 mm Hg. The discharge magnetic field (MF) has been investigated by a system of five magnetic probes both oriented along the radius and the length of the discharge chamber. The longitudinal temperature of electrons reaches 4 keV at the 6 kV voltage on the coil. Successive development of two types of instability has been observed: HF ''starting'' and LF ones. The LF oscillations observed have been identified as drift waves in a system with large β. The amplitude of the MF oscillations for the given instability may be compared with the value of the main MF, and the transverse wave lengths for these oscillations are of the order of the plasma filament radius. The longitudinal wave lengths are comparable with the magnetic system length

  17. Wave Grouping of a Drifting Spiral Wave in the Presence of an External Field

    Institute of Scientific and Technical Information of China (English)

    YANG Hu-Jiang; YANG Jun-Zhong; HU Gang

    2007-01-01

    The phenomenon of wave grouping, in which the dense waves and the sparse waves can form groups in front of the spiral tip when the spiral wave is meandering, has been reported in a chemical reaction system recently. We present a method to realize the phenomenon of wave grouping by applying an external field to the system. The numerical simulations are carried out on the basis of the FitzHugh-Nagumo equations.

  18. Global Theories of Geodesic Acoustic Modes: Excitation by Energetic Particles and Drift Wave Turbulences

    International Nuclear Information System (INIS)

    Full text: Excitation of Geodesic Acoustic Modes (GAMs) by both energetic particles (EPs) and drift wave (DW) turbulences taking into account plasma nonuniformities are investigated in this work. The global radial mode structures of EP induced GAM (EGAM) are systematically studied and their properties are found to depend on the nonuniformities of both the GAM continuous spectrum and EP radial profile. For a radially broad EP drive, the eigenmode equation valid for arbitrary EP drift orbit width is derived, and then solved using a Fourier transformation technique. The excited EGAM is shown to strongly couple to the GAM continuous spectrum; resulting in a finite drive threshold in EP density. The cross-scale couplings between micro-, meso- and macro-scales, discussed in this work, are mediated by the EP dynamics and have many interesting similarities with complex behaviors, expected in burning plasmas of fusion interest. The excitation of GAM by DW turbulence accounting for various kinetic dispersiveness and nonuniformities is also investigated, with the paradigm of three-wave resonant parametric decay instability. Considering the scale length of linear DW eigenmode envelope is much smaller than that of particle diamagnetic drift frequency L*, in the linear growth phase, the parametric instability is convective for typical tokamak parameters, when the finite group velocities of GAM and DW sideband are taken into account. This is a case of less practical interest. However, if we look at longer time scales, and finite L* effects are taken into account, the convectively amplified GAM-DW wave-packet pair is reflected at the DW linear turning points, resulting in a quasi-exponentially growing absolute instability. DW turbulence spreading with the excitation of GAM is also investigated, with emphasis on quantitative understanding of the dispersiveness associated with kinetic GAM. (author)

  19. Transport analysis of JT-60 plasma by drift wave turbulence model

    International Nuclear Information System (INIS)

    Characteristics of JT-60 plasma in both ohmic and neutral beam heating phase are numerically studied by using the one dimensional tokamak transport code with thermal conductivities based on the drift wave turbulence model. The numerical results show good agreement with experimental data in the medium electron density range n-bare ∼ 4 x 1019 m-3 both for ohmic and neutral beam heating cases. On the contrary, the model underestimates the plasma temperatures in the low electron density range because of the strong dependence of thermal conductivities on electron temperature, and can not reproduce high temperature plasmas. (author)

  20. Dispersion relation of drift-wave instability in a collisionless plasma with sheared magnetic field

    International Nuclear Information System (INIS)

    Detailed measurements are performed on drift-wave instability in a collisionless plasma column under a sheared magnetic field. The instability is found to be destabilized by the small magnetic shear and has a maximum amplitude at the shear length, where the electron thermal speed is nearly equal to the axial phase velocity (controlled by the shear) of the instability. The dispersion relation of the instability agrees with the local theory, which yields almost the same results as the non-local theory taking into account the measured radial density profile of a slender plasma column. (author)

  1. Two-dimensional aspects of toroidal drift waves in the ballooning representation

    International Nuclear Information System (INIS)

    By systematically doing the higher-order theory, the predictions of the conventional ballooning theory (CBT) are examined for nonideal systems. For the complex solvability condition to be satisfied, radial variation of the lowest-order mode amplitude needs to be invoked. It turns out, however, that even this procedure with its concomitant modifications of eigenvalues and eigenstructures, is not sufficient to justify the predictions of many CBT solutions; only a small set of the CBT solutions could be put on firm footing. To demonstrate this work's general conclusions, theoretical and numerical results are presented for a system of fluid drift waves with nonadiabatic electron response

  2. Two dimensional aspects of toroidal drift waves in the ballooning representation

    International Nuclear Information System (INIS)

    By systematically doing the higher order theory, the predictions of the conventional ballooning theory (CBT) are examined for non-ideal systems. For the complex solvability condition to be satisfied, radial variation of the lowest order mode amplitude needs to be invoked. It turns out, however, that even this procedure with its concomitant modifications of eigenvalues and eigenstructures, is not sufficient to justify the predictions of many CBT solutions; only a small set of CBT solutions could be put on a firm footing. To demonstrate our general conclusions, theoretical and numerical results are presented for system of fluid drift waves non-adiabatic electron response

  3. Scattering of lower-hybrid waves by drift-wave density fluctuations: solutions of the radiative transfer equation

    International Nuclear Information System (INIS)

    The investigation of the scattering of lower-hybrid waves by density fluctuations arising from drift waves in tokamaks is distinguished by the presence in the wave equation of a large, random, derivative-coupling term. The propagation of the lower-hybrid waves is well represented by a radiative transfer equation when the scale size of the density fluctuations is small compared to the overall plasma size. The radiative transfer equation is solved in two limits: first, the forward scattering limit, where the scale size of density fluctuations is large compared to the lower-hybrid perpendicular wavelength, and second, the large-angle scattering limit, where this inequality is reversed. The most important features of these solutions are well represented by analytical formulas derived by simple arguments. Based on conventional estimates for density fluctuations arising from drift waves and a parabolic density profile, the optical depth tau for scattering through a significant angle, is given by tauroughly-equal(2/N2/sub parallel/) (#betta#/sub p/i0/#betta#)2 (m/sub e/c2/2T/sub i/)/sup 1/2/ [c/α(Ω/sub i/Ω/sub e/)/sup 1/2/ ], where #betta#/sub p/i0 is the central ion plasma frequency and T/sub i/ denotes the ion temperature near the edge of the plasma. Most of the scattering occurs near the surface. The transmission through the scattering region scales as tau-1 and the emerging intensity has an angular spectrum proportional to cos theta, where sin theta = k/sub perpendicular/xB/sub p//(k/sub perpendicular/B/sub p/), and B/sub p/ is the poloidal field

  4. Spontaneous profile self-organization in a simple realization of drift-wave turbulence

    Science.gov (United States)

    Cui, L.; Ashourvan, A.; Thakur, S. C.; Hong, R.; Diamond, P. H.; Tynan, G. R.

    2016-05-01

    We report the observation of a transport bifurcation that occurs by spontaneous self-organization of a drift-wave and shear flow system in a linear plasma device. As we increase the magnetic field above a threshold ( BC r = 1200 G), a global transition occurs, with steepening of mean density and ion pressure profiles, onset of strong E ×B shearing, a reduction of turbulence, and improved turbulent radial particle transport. An abrupt transition appears in the graph of turbulent particle flux versus density gradient. Hysteresis in the density gradient further confirms this transport bifurcation. The total Reynolds work on the flow sharply increases above threshold. This correlates with the increase of density steepness, which suggests the Reynolds stress-driven flow that plays an essential role in density steepening and transport bifurcation. A change in turbulence feature from drift waves (DWs) to a mix of DWs and ion temperature gradients also coincides with the transport bifurcation. Interesting phenomena related to the transport bifurcation are also reported; a local inward particle flux, the co-existence of ion and electron features, and a self-sustained axial flow absent momentum input.

  5. Simulating the coupled evolution of drift-wave turbulence and the tearing mode

    Science.gov (United States)

    James, S. D.; Brennan, D. P.; Izacard, O.; Holland, C.

    2015-11-01

    Numerical simulations of turbulence and MHD instabilities such as the tearing mode can be computationally expensive and only recently have simulations begun to address their coupled, self-consistent interactions. The disparate scales involved in simulating the coupled evolution of small-scale turbulence and the larger-scale tearing mode make this a challenging numerical problem. Using the newly developed code, TURBO, we have performed nonlinear simulations of Hasegawa-Wakatani drift-wave turbulence coupled to Ohm's law. An equilibrium with prescribed stability properties and turbulent drives is used to examine the impact of drift-wave turbulence on the stability of the tearing mode and the energy transport between them in the context of a turbulent resistivity and turbulent viscosity. We find that the spatial structure of the density flux and these transport coefficients are asymmetric in the poloidal direction and peaked away from the X-point in the presence of an island in a poloidal flow. Similar effects are seen in simulations of ITG turbulence in the presence of a magnetic island and we discuss the connections to our work. Supported by US DOE Grant DE-SC0007851.

  6. Drift wave spectra and enhanced transport in plasmas with magnetic shear

    International Nuclear Information System (INIS)

    We investigate the potentialities of nonlinear scattering of waves off ions as a stabilizing mechanism of drift turbulence in plasmas with magnetic shear. The failure of the random phase averaging procedure and the local character of the interaction in frequency space are the starting point of a reformulation of weak turbulence theory. In particular, the usual integral equation is transformed into a system of two first order differential equations coupling the spectra I(ksub(theta)) and I(ksub(theta)-1). The density fluctuation spectrum, which is obtained analytically, has some desirable features in reference to experiment. Firstly, |eta tilde|ksub(theta)2 behaves asymptotically (ksub(theta) → infinity) as ksub(theta)-4; secondly, the high mode numbers (ksub(theta)asub(s) >1) contribute about 80% to the cross field diffusion while the low mode numbers (ksub(theta)asub(s) <1) provide about 80% of the squared density fluctuation. In discussing the transport properties we emphasize the possible role of anomalous heat transfer from electrons to ions. The spectrum of convective cells formed in the interaction of drift waves is obtained; their contribution to the diffusion is found to be negligible, at least in the plasma core. (author)

  7. Discrete exact and quasi-resonances of Rossby/drift waves on $\\b$-plane with periodic boundary conditions

    OpenAIRE

    Kartashov, A.; E. Kartashova

    2013-01-01

    Analysis of resonance clustering in weakly nonlinear dispersive wave systems, also called discrete wave turbulent systems, is a new methodology successfully used in the last years for characterizing energy transport due to exact and quasi-resonances. Quite recently this methodology has been used in the paper by M. D. Bustamante, U. Hayat "Complete classification of discrete resonant Rossby/drift wave triads on periodic domains", \\cite{BH13}, in order to show that resonance clustering is very ...

  8. Non-Linear Drift Waves in a Plasma with a Temperature Gradient

    International Nuclear Information System (INIS)

    In a low-β plasma slab we consider stationary drift waves with an electrostatic potential of the type φ(y-ut, x, z), where x is the co-ordinate in the direction of the equilibrium gradients, and z is the co-ordinate along the magnetic field. We assume the x-dependence of the varying quantities to be small, the ion temperature to be much smaller than the electron temperature, and make use of the two-fluid theory neglecting the dissipative effects. We take into account the electron temperature gradient as was done previously, but add the dispersive effects due to the ion inertia perpendicular to B. The final equation is similar to the Korteweg-de Vries equation. It has as solutions a general non-linear wave, a solitary wave and an exact sinus wave. The two last solutions are due to the temperature gradient. In the dissipative case, resistivity alone does not allow periodic solutions if solutions of the type φ(y-ut + az) are considered. The x-dependence of potential and density fluctuations seems to be essential for the calculation of the diffusion averaged over one period of oscillation. (author)

  9. Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

    International Nuclear Information System (INIS)

    Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition between collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.

  10. Diffusive and drift regimes of propagation of a plane ionization wave in a microwave field

    International Nuclear Information System (INIS)

    The simplest one-dimensional model including the electron-impact ionization of a gas in the electric field, electron attachment, mobility and diffusion is used to show that (a) in a supercritical microwave (MW) field, an ionization wave with a steady-state profile is formed, which can propagate through a gas in the absence of preionization; (b) two substantially different regimes of propagation of the discharge can occur--diffusive and drift ones; (c) in the diffusive regime, the ion mobility is almost insignificant, and only electron (rather than ambipolar) diffusion is important; (d) in the drift regime, the velocity of the ionization front depends only slightly on the electron diffusion coefficient, depends on the ratio of the ionization frequency to the MW field frequency, and can considerably (by several orders of magnitude) exceed the velocity of the ionization front corresponding to the diffusive regime. The dependences of the velocity, shape and length of the ionization front on the gas pressure and on the ratio of the MW field amplitude to the critical value of electric field are found

  11. Small scale coherent vortex generation in drift wave-zonal flow turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Z. B., E-mail: guozhipku@gmail.com; Hahm, T. S. [Seoul National University, Seoul 151-744 (Korea, Republic of); Diamond, P. H. [CMTFO and CASS, University of California, San Diego, California 92093 (United States)

    2015-12-15

    We present a paradigm for the generation of small scale coherent vortex (SSCV) in drift wave-zonal flow (DW-ZF) turbulence. We demonstrate that phases of DWs can couple coherently, mediated by the ZF shearing. A SSCV is formed when the phases of the DWs are “attracted” to form a stable “phase cluster.” We show that the ZF shearing induces asymmetry between “attractive” and “repulsive” phase couplings, so that a net attractive phase coupling results. The turbulent DWs will (partially)synchronize into a stable SSCV at locations, where the attractive phase coupling induced by the ZF shearing exceeds the “detuning” effects by the DW dispersion and random phase scattering. We also discuss the “self-binding” effect of the newly formed SSCV.

  12. Small scale coherent vortex generation in drift wave-zonal flow turbulence

    International Nuclear Information System (INIS)

    We present a paradigm for the generation of small scale coherent vortex (SSCV) in drift wave-zonal flow (DW-ZF) turbulence. We demonstrate that phases of DWs can couple coherently, mediated by the ZF shearing. A SSCV is formed when the phases of the DWs are “attracted” to form a stable “phase cluster.” We show that the ZF shearing induces asymmetry between “attractive” and “repulsive” phase couplings, so that a net attractive phase coupling results. The turbulent DWs will (partially)synchronize into a stable SSCV at locations, where the attractive phase coupling induced by the ZF shearing exceeds the “detuning” effects by the DW dispersion and random phase scattering. We also discuss the “self-binding” effect of the newly formed SSCV

  13. Non-perturbative statistical theory of intermittency in ITG drift wave turbulence with zonal flows

    International Nuclear Information System (INIS)

    The probability distribution functions (PDFs) of momentum flux and zonal flow formation in ion-temperature-gradient (ITG) turbulence are investigated in two different models. The first is a general five-field model (ni, φ, Ti, Te, vi||) where a reductive perturbation method is used to derive dynamical equations for drift waves and a zonal flow. The second is a reduced two-field model (φ, Ti) that has an exact non-linear solution (bipolar vortex soliton). In both models the exponential tails of the zonal flow PDFs are found with the same scaling (PDF ∼ exp {- cZFφZF3}), but with different coefficients cZF. The PDFs of momentum flux is, however, found to be qualitatively different with the scaling (PDF ∼ exp{-cMRs}), where s = 2 and s = 3/2 in the five and two-field models, respectively.

  14. Effects of a poloidally asymmetric ionization source on toroidal drift wave stability and the generation of sheared parallel flow

    International Nuclear Information System (INIS)

    The effects of a poloidally asymmetric ionization source on both dissipative toroidal drift wave stability and the generation of mean sheared parallel flow are examined. The first part of this work extends the development of a local model of ionization-driven drift wave turbulence [Phys. Fluids B 4, 877 (1992)] to include the effects of magnetic shear and poloidal source asymmetry, as well as poloidal mode coupling due to both magnetic drifts and the source asymmetry. Numerical and analytic investigation confirm that ionization effects can destabilize collisional toroidal drift waves. However, the mode structure is determined primarily by the magnetic drifts, and is not overly effected by the poloidal source asymmetry. The ionization source drives a purely inward particle flux, which can explain the anomalously rapid uptake of particles which occurs in response to gas puffing. In the second part of this work, the role poloidal asymmetries in both the source and turbulent particle diffusion play in the generation of sheared mean parallel flow is examined. Analysis indicates that predictions of sonic parallel shear flow [vparallel(r)∼cs] are an unphysical result of the assumption of purely parallel flow (i.e., vperpendicular=0) and the neglect of turbulent parallel momentum transport. Results indicate that the flow produced is subcritical to the parallel shear flow instability when diamagnetic effects are properly considered

  15. The mechanism of self-sustainment in collisional drift-wave turbulence

    International Nuclear Information System (INIS)

    Although collisional drift waves in a sheared slab configuration are linearly damped, it is found that the corresponding turbulence is self-sustaining if initialized at nonlinear amplitude. The influence of the free energy source represented by the temperature and density gradients on the turbulent system involving bi-directional spectral energy transfer is responsible for this change of regime, manifested through an indetifiably self-organized mode structure. Fluctuation mode widths are determined by a competition between turbulent advective broadening and parallel dissipation. All of the features of nonlinear mode structure are thereby determined by nonlinear processes, divesting linear stability criteria of their relevance to that structure, or its amplitude. Detailed study with the computations suggests: (a) The threshold amplitude for nonlinear self-sustainment is somewhat less than ρs/Ln, weakly dependent on parameters. (b) In the 2D slab, increasingly strong temperature gradient relative to density exacerbates collisional dissipation, introducing a nonlinear stability boundary. (c) Effects of neighboring rational surfaces are judged through the overlap criterion, which shows that the self-organized part does not overlap, but the free-energy tapping part does, leading to the expectation that gradients can be maintained in the tokamak, and that much of the small-scale side of collisional dissipation should be suppressed, enhancing the turbulence in the tokamak edge. (d) The introduction of rvec Ex rvec B shear flows with gradients as large as cs/Ln does not suppress this turbulence, but nonlinearly enhances it for strong enough shear (cs/Ln). Many important features of experimentally observed tokamak edge fluctuations are reproduced by these single-rational-surface nonlinear dynamics. Consequently, one must continue to consider drift-wave turbulence as a plausible mechanism behind such observations

  16. A kinetic theory of trapped electron driven drift wave turbulence in a sheared magnetic field

    International Nuclear Information System (INIS)

    A kinetic theory of collisionless and dissipative trapped electron driven drift wave turbulence in a sheared magnetic field is presented. Weak turbulence theory is employed to calculate the nonlinear electron and ion responses and to derive a wave kinetic equation that determines the nonlinear evolution of trapped electron mode turbulence. Saturated fluctuation spectrum is calculated using the condition of nonlinear saturation. The turbulent transport coefficients are in turn calculated using saturated fluctuation spectrum. Due to the disparity in the three different radial scale lengths of the slab-like eigenmode: Δ (trapped electron layer width), xt (turning point width) and xi (Landau damping point), Δ t i, we find that ion Compton scattering rather than trapped electron Compton scattering is the dominant nonlinear saturation mechanism. Ion Compton scattering transfers wave energy from short to long wavelengths where the wave energy is shear damped. As a consequence, a saturated fluctuation spectrum |φ|2(kθ) ∼ kθ-α (α = 2 and 3 for the dissipative and collisionless regime, respectively) occurs for kθρs θρs > 1. The predicted fluctuation level and transport coefficients are well below the ''mixing length'' estimate. This is due to the contribution of radial wavenumbers xt-1 r ≤ ρi-1 to the nonlinear couplings, the effect of radial localization of trapped electron response to a layer of width, Δ, and the weak turbulence factor left-angle(γel)/(ωrvecκ)right-angle rveck < 1, which enters the saturation level. 18 refs., 1 tab

  17. Precursor wave structure, prereversal vertical drift, and their relative roles in the development of post sunset equatorial spread-F

    Science.gov (United States)

    Abdu, Mangalathayil; Sobral, José; alam Kherani, Esfhan; Batista, Inez S.; Souza, Jonas

    2016-07-01

    The characteristics of large-scale wave structure in the equatorial bottomside F region that are present during daytime as precursor to post sunset development of the spread F/plasma bubble irregularities are investigated in this paper. Digisonde data from three equatorial sites in Brazil (Fortaleza, Sao Luis and Cachimbo) for a period of few months at low to medium/high solar activity phases are analyzed. Small amplitude oscillations in the F layer true heights, representing wave structure in polarization electric field, are identified as upward propagating gravity waves having zonal scale of a few hundred kilometers. Their amplitudes undergo amplification towards sunset, and depending on the amplitude of the prereversal vertical drift (PRE) they may lead to post sunset generation of ESF/plasma bubble irregularities. On days of their larger amplitudes they appear to occur in phase coherence on all days, and correspondingly the PRE vertical drift velocities are larger than on days of the smaller amplitudes of the wave structure that appear at random phase on the different days. The sustenance of these precursor waves structures is supported by the relatively large ratio (approaching unity) of the F region-to- total field line integrated Pedersen conductivities as calculated using the SUPIM simulation of the low latitude ionosphere. This study examines the role of the wave structure relative to that of the prereversal vertical drift in the post sunset spread F irregularity development.

  18. Rossby and drift wave turbulence and zonal flows: The Charney-Hasegawa-Mima model and its extensions

    Science.gov (United States)

    Connaughton, Colm; Nazarenko, Sergey; Quinn, Brenda

    2015-12-01

    A detailed study of the Charney-Hasegawa-Mima model and its extensions is presented. These simple nonlinear partial differential equations suggested for both Rossby waves in the atmosphere and drift waves in a magnetically-confined plasma, exhibit some remarkable and nontrivial properties, which in their qualitative form, survive in more realistic and complicated models. As such, they form a conceptual basis for understanding the turbulence and zonal flow dynamics in real plasma and geophysical systems. Two idealised scenarios of generation of zonal flows by small-scale turbulence are explored: a modulational instability and turbulent cascades. A detailed study of the generation of zonal flows by the modulational instability reveals that the dynamics of this zonal flow generation mechanism differ widely depending on the initial degree of nonlinearity. The jets in the strongly nonlinear case further roll up into vortex streets and saturate, while for the weaker nonlinearities, the growth of the unstable mode reverses and the system oscillates between a dominant jet, which is slightly inclined to the zonal direction, and a dominant primary wave. A numerical proof is provided for the extra invariant in Rossby and drift wave turbulence-zonostrophy. While the theoretical derivations of this invariant stem from the wave kinetic equation which assumes weak wave amplitudes, it is shown to be relatively well-conserved for higher nonlinearities also. Together with the energy and enstrophy, these three invariants cascade into anisotropic sectors in the k-space as predicted by the Fjørtoft argument. The cascades are characterised by the zonostrophy pushing the energy to the zonal scales. A small scale instability forcing applied to the model has demonstrated the well-known drift wave-zonal flow feedback loop. The drift wave turbulence is generated from this primary instability. The zonal flows are then excited by either one of the generation mechanisms, extracting energy from

  19. Rossby and Drift Wave Turbulence and Zonal Flows: the Charney-Hasegawa-Mima model and its extensions

    CERN Document Server

    Connaughton, Colm; Quinn, Brenda

    2014-01-01

    A detailed study of the Charney-Hasegawa-Mima model and its extensions is presented. These simple nonlinear partial differential equations suggested for both Rossby waves in the atmosphere and also drift waves in a magnetically-confined plasma exhibit some remarkable and nontrivial properties, which in their qualitative form survive in more realistic and complicated models, and as such form a conceptual basis for understanding the turbulence and zonal flow dynamics in real plasma and geophysical systems. Two idealised scenarios of generation of zonal flows by small-scale turbulence are explored: a modulational instability and turbulent cascades. A detailed study of the generation of zonal flows by the modulational instability reveals that the dynamics of this zonal flow generation mechanism differ widely depending on the initial degree of nonlinearity. A numerical proof is provided for the extra invariant in Rossby and drift wave turbulence -zonostrophy and the invariant cascades are shown to be characterised...

  20. Early stages of wind wave and drift current generation under non-stationary wind conditions.

    Science.gov (United States)

    Robles-Diaz, Lucia; Ocampo-Torres, Francisco J.; Branger, Hubert

    2016-04-01

    Generation and amplification mechanisms of ocean waves are well understood under constant wind speed or limited fetch conditions. Under these situations, the momentum and energy transfers from air to water are also quite well known. However during the wind field evolution over the ocean, we may observe sometime high wind acceleration/deceleration situations (e.g. Mexican Tehuano or Mediterranean Mistral wind systems). The evolution of wave systems under these conditions is not well understood. The purpose of these laboratory experiments is to better understand the early stages of water-waves and surface-drift currents under non-stationary wind conditions and to determine the balance between transfers creating waves and surface currents during non-equilibrium situations. The experiments were conducted in the Institut Pythéas wind-wave facility in Marseille-France. The wave tank is 40 m long, 2.7 m wide and 1 m deep. The air section is 50 m long, 3 m wide and 1.8 m height. We used 11 different resistive wave-gauges located along the tank. The momentum fluxes in the air column were estimated from single and X hot-film anemometer measurements. The sampling frequency for wind velocity and surface displacement measurements was 256 Hz. Water-current measurements were performed with a profiling velocimeter. This device measures the first 3.5 cm of the water column with a frequency rate of 100Hz. During the experiments, the wind intensity was abruptly modified with a constant acceleration and deceleration over time. We observed that wind drag coefficient values for accelerated wind periods are lower than the ones reported in previous studies for constant wind speed (Large and Pond 1981; Ocampo-Torres et al. 2010; Smith 1980; Yelland and Taylor 1996). This is probably because the turbulent boundary layer is not completely developed during the increasing-wind sequence. As it was reported in some theoretical studies (Miles 1957; Phillips 1957; Kahma and Donelan 1988), we

  1. Experimental investigations of structure and dynamics of drift-wave turbulence in stellarator geometry

    International Nuclear Information System (INIS)

    For more than 60 years, fusion scientists try to confine a plasma by means of external magnetic fields in order to achieve appropriately high densities and temperatures for the ignition of nuclear fusion. Despite of great progress in the design of confinement concepts, which are considered for the confinement of burning plasmas in the near future, theoretical plasma physics promises further confinement improvements using novel magnetic field geometries. Therefor, the key is the minimization of turbulent transport by choosing appropiate magnetic field geometries, which necessitates a fundamental understanding of the influence of magnetic field geometry on plasma turbulence. There are several theoretical works on turbulent plasma dynamics in three-dimensional geometries, but only a few experimental studies for validation of the theoretical results exist. Hence, the present work aims at providing experimental data for comparison with theory and to gain insights into the interplay between drift-wave turbulence and magnetic field geometry. By means of two multi-probe arrays, local density and potential fluctuations are measured in low-temperature plasmas at 128 positions on a single flux surface of the stellarator TJ-K with high temporal resolution. Using methods of statistical timeseries analysis structure sizes and dynamic properties of the drift-wave turbulence in TJ-K are determined. Thereby, it is shown that the size of turbulent structures perpendicular to the magnetic field is reduced in regions of high absolute local magnetic shear. In addition, a poloidal displacement with respect to the magnetic field lines and a complex propagation pattern of parallelly extended turbulent structures is found. Also, poloidal profiles of turbulent transport are calculated from the probe data. The maximum transport is found to be poloidally localized in a region of negative normal curvature (unfavourable curvature). In addition, the results point to an influence of geodesic

  2. Lithium-Drifted Germanium Detectors for High Resolution Beta- and Gamma-Ray Spectroscopy

    International Nuclear Information System (INIS)

    Two types of germanium detectors have been fabricated using the lithium-ion drift technique. The first type have active volumes in excess of 6 cm3 and are primarily intended for high-energy (> 1.0 MeV) y-ray spectroscopy. The second type are large area, low capacity, windowless detectors intended for very high-resolution 6-ray and low-energy y-ray spectroscopy. Both types are operated in a vacuum at liquid nitrogen temperature (77°K). The large-volume detectors have areas greater than 6 cm2 with depletion depths in excess of 1 cm. The experimental resolution (FWHM) obtainable with these detectors is limited at low energies by the noise level of the pre-amplifier, while at high energies (>1MeV) the 1 imitation is due to amplifier instability. Typical resolutions are 3,6, and 12 keV for 0,122, 1,333and 5.0 MeV γ-rays respectively, while the photopeak efficiency ranges from approximately 75% at 122 keV to 1% at 1.333 MeV and 0. % at 5 MeV. At 5 MeV the pair-peak efficiency is ∼5%. Typical low-capacity detectors are slices (less than 5 mm thick) from the large volume detectors and have an area of 3 x 1 cm (the depletion depth). This gives a reduction in detector capacitance which results in a significant improvement in the resolution compared to that obtained with the large-volume detectors for a given pre-amplifier. At 0.122 and 1.333 MeV, resolutions of 1.9 keV and 4.1 keV respectively have been observed. Since these are essentially windowless detectors they make excellent small β-ray spectrometers. Typical resolution for the 625-keV K conversion electrons of 137Cs is less than 6 keV. These detectors are finding an increasingly wider application in both nuclear decay scheme work and in identifying the isotopic content of samples containing many isotopes. A more detailed evaluation of the properties and various applications of these two types of germanium detectors is described. (author)

  3. Complete classification of discrete resonant Rossby/drift wave triads on periodic domains

    Science.gov (United States)

    Bustamante, Miguel D.; Hayat, Umar

    2013-09-01

    We consider the set of Diophantine equations that arise in the context of the partial differential equation called "barotropic vorticity equation" on periodic domains, when nonlinear wave interactions are studied to leading order in the amplitudes. The solutions to this set of Diophantine equations are of interest in atmosphere (Rossby waves) and Tokamak plasmas (drift waves), because they provide the values of the spectral wavevectors that interact resonantly via three-wave interactions. These wavenumbers come in "triads", i.e., groups of three wavevectors. We provide the full solution to the Diophantine equations in the physically sensible limit when the Rossby deformation radius is infinite. The method is completely new, and relies on mapping the unknown variables via rational transformations, first to rational points on elliptic curves and surfaces, and from there to rational points on quadratic forms of "Minkowski" type (such as the familiar space-time in special relativity). Classical methods invented centuries ago by Fermat, Euler, Lagrange, Minkowski, are used to classify all solutions to our original Diophantine equations, thus providing a computational method to generate numerically all the resonant triads in the system. Computationally speaking, our method has a clear advantage over brute-force numerical search: on a 10,0002 grid, the brute-force search would take 15 years using optimised C codes on a cluster, whereas our method takes about 40 min using a laptop. Moreover, the method is extended to generate so-called quasi-resonant triads, which are defined by relaxing the resonant condition on the frequencies, allowing for a small mismatch. Quasi-resonant triads' distribution in wavevector space is robust with respect to physical perturbations, unlike resonant triads' distribution. Therefore, the extended method is really valuable in practical terms. We show that the set of quasi-resonant triads form an intricate network of connected triads, forming

  4. Modification of low-frequency drift oscillation spectra in the field of HF pumping wave near the lower hybrid resonance

    International Nuclear Information System (INIS)

    The effect of a high-frequency pumping wave on ionic-sound drift oscillations, whose frequency exceeds the ionic cyclotron one, is experimentally studied. A cylinder pinch was produced in a homogeneous magnetic field by a beam of low-energy electrons. The strength of a stationary magnetic field oriented along the plasma cylinder axis amounted to 400-600 Oe. The concentration of plasma was approximately 1010 cm3, the temperature of electrons approximately 6 eV, the pressure of a neutral gas (argon) was approximately 2-3x10-4 Tor. Low-frequency drift oscillations were recorded by single probes operating in a regime of saturation ionic current, and also by a photomultiplier tube according to integral luminous radiation of plasma. It is shown that threshold-less modificatjon of frequency spectrum of ionic-sound drift oscillations takes place with increasing high-frequency pumping field, and that they are incompletely suppressed from the side of hjgher frequencies. Displacement of peaks in the spectra of drift oscillations to the side of high values of frequency was observed at the values of a high-frequency pumping field Esub(0) <= 3 V/cm. It is shown that the less is the frequency of a pumping wave the sharper is the decrease in the drift oscillation intensity with increasing Esub(0). A comparison of experimental and theoretical data shows that the HF-field component normal to the magnetic fjeld may produce an essential influence upon the dynamics of drift-dissipative instability

  5. Simulation of drift wave turbulence: Trapped structures and a new nonadiabatic electron model

    International Nuclear Information System (INIS)

    The development of trapped structures in decaying and saturated drift wave turbulence is studied via computer simulation. A two-dimensional electrostatic fluid model is used. The turbulence which evolves in the pure decay runs (no nonadiabatic electrons) is characterized by tightly bound monopole vortices and a very narrow frequency spectrum. These results are qualitatively similar to results found in two dimensional Navier-Stokes simulations. For the studies of saturated turbulence, rather than simply introducing the linear growth rate, a new nonadiabatic electron model is used. This model takes into account the effects of broadening and shifting of the frequency spectrum which results from the strongly nonlinear character of the problem--effects which are found to be very important in the turbulent states which are studied. These states are characterized by broadened frequency spectra, with strong damping on the nonadiabatic electrons at high-k and along the kx-axis. Trapped structures are observed in many of the saturated simulations, even in the presence of moderately broad frequency spectra. The extent of the trapping varied dramatically, becoming a much stronger effect as the RMS electric field increased. 71 refs., 39 figs., 11 tabs

  6. Effects of drift gas on collision cross sections of a protein standard in linear drift tube and traveling wave ion mobility mass spectrometry.

    Science.gov (United States)

    Jurneczko, Ewa; Kalapothakis, Jason; Campuzano, Iain D G; Morris, Michael; Barran, Perdita E

    2012-10-16

    There has been a significant increase in the use of ion mobility mass spectrometry (IM-MS) to investigate conformations of proteins and protein complexes following electrospray ionization. Investigations which employ traveling wave ion mobility mass spectrometry (TW IM-MS) instrumentation rely on the use of calibrants to convert the arrival times of ions to collision cross sections (CCS) providing "hard numbers" of use to structural biology. It is common to use nitrogen as the buffer gas in TW IM-MS instruments and to calibrate by extrapolating from CCS measured in helium via drift tube (DT) IM-MS. In this work, both DT and TW IM-MS instruments are used to investigate the effects of different drift gases (helium, neon, nitrogen, and argon) on the transport of multiply charged ions of the protein myoglobin, frequently used as a standard in TW IM-MS studies. Irrespective of the drift gas used, recorded mass spectra are found to be highly similar. In contrast, the recorded arrival time distributions and the derived CCS differ greatly. At low charge states (7 ≤ z ≤ 11) where the protein is compact, the CCS scale with the polarizability of the gas; this is also the case for higher charge states (12 ≤ z ≤ 22) where the protein is more unfolded for the heavy gases (neon, argon, and nitrogen) but not the case for helium. This is here interpreted as a different conformational landscape being sampled by the lighter gas and potentially attributable to increased field heating by helium. Under nanoelectrospray ionization (nESI) conditions, where myoglobin is sprayed from an aqueous solution buffered to pH 6.8 with 20 mM ammonium acetate, in the DT IM-MS instrument, each buffer gas can yield a different arrival time distribution (ATD) for any given charge state. PMID:22974196

  7. Spatial structure and dispersion of drift mirror waves coupled with Alfvén waves in a 1-D inhomogeneous plasma

    Directory of Open Access Journals (Sweden)

    D. Yu. Klimushkin

    2006-09-01

    Full Text Available The paper employs the frame of a 1-D inhomogeneous model of space plasma,to examine the spatial structure and growth rate of drift mirror modes, often suggested for interpreting some oscillation types in space plasma. Owing to its coupling with the Alfvén mode, the drift mirror mode attains dispersion across magnetic shells (dependence of the frequency on the wave-vector's radial component, kr. The spatial structure of a mode confined across magnetic shells is studied. The scale of spatial localization of the wave is shown to be determined by the plasma inhomogeneity scale and by the azimuthal component of the wave vector. The wave propagates across magnetic shells, its amplitude modulated along the radial coordinate by the Gauss function. Coupling with the Alfvén mode strongly influences the growth rate of the drift mirror instability. The mirror mode can only exist in a narrow range of parameters. In the general case, the mode represents an Alfvén wave modified by plasma inhomogeneity.

  8. Suppression of drift wave turbulence and zonal flow formation by changing axial boundary conditions in a cylindrical magnetized plasma device

    International Nuclear Information System (INIS)

    For drift wave turbulence, due to charge conservation, the divergence of the parallel current is coupled to the divergence of the perpendicular polarization current, which determines the effective radial momentum flux, i.e., the Reynolds stress. Changes in the current flow patterns also affect the nonlinear energy transfer from smaller to larger scales. Here, we show that by changing the end plate boundary conditions in a cylindrical plasma device, the radial currents through the plasma and hence the net momentum transport and the nonlinear coupling for the inverse energy transfer are strongly modified. The transition to drift wave turbulence and the formation of low frequency zonal flows can be either suppressed with conducting boundaries or enhanced with insulating boundaries.

  9. Resolving Structural Isomers of Monosaccharide Methyl Glycosides Using Drift Tube and Traveling Wave Ion Mobility Mass Spectrometry

    OpenAIRE

    Li, Hongli; Giles, Kevin; Bendiak, Brad; Kaplan, Kimberly; Siems, William F.; Hill, Herbert H.

    2012-01-01

    Monosaccharide structural isomers including sixteen methyl-D-glycopyranosides and four methyl-N-acetylhexosamines were subjected to ion mobility measurements by electrospray ion mobility mass spectrometry. Two ion mobility-MS systems were employed: atmospheric pressure drift tube ion mobility time-of-flight mass spectrometry and a Synapt G2 HDMS system which incorporates a low pressure traveling wave ion mobility separator. All the compounds were investigated as [M+Na]+ ions in the positive m...

  10. A statistical study of gyro-averaging effects in a reduced model of drift-wave transport

    CERN Document Server

    da Fonseca, J D; Sokolov, M; Caldas, I L

    2016-01-01

    A statistical study of finite Larmor radius (FLR) effects on transport driven by electrostatic drift-waves is presented. The study is based on a reduced discrete Hamiltonian dynamical system known as the gyro-averaged standard map (GSM). In this system, FLR effects are incorporated through the gyro-averaging of a simplified weak-turbulence model of electrostatic fluctuations. Formally, the GSM is a modified version of the standard map in which the perturbation amplitude, $K_0$, becomes $K_0 J_0(\\hat{\\rho})$, where $J_0$ is the zeroth-order Bessel function and $\\hat{\\rho}$ is the Larmor radius. Assuming a Maxwellian probability density function (pdf) for $\\hat{\\rho}$, we compute analytically and numerically the pdf and the cumulative distribution function of the effective drift-wave perturbation amplitude $K_0 J_0(\\hat{\\rho})$. Using these results we compute the probability of loss of confinement (i.e., global chaos), $P_{c}$, and the probability of trapping in the main drift-wave resonance, $P_{t}$. It is sho...

  11. A note on the drift waves in the presence of electrons added by meteors by ablation phenomena or by thermionic emissions

    Indian Academy of Sciences (India)

    V H Kulkarni; Shobha Kadam

    2012-07-01

    The role of added electrons on the drift dissipative instability in a nonuniform collisional plasma is analysed. We observe the presence of a drift wave that depends entirely on the added electrons through the collision frequency coupling and there is an additional damping. The present study is applied to the density irregularities caused by meteor ionization in the ionosphere.

  12. Music genre preference and tempo alter alpha and beta waves in human non-musicians

    Directory of Open Access Journals (Sweden)

    Hunter Gentry

    2013-10-01

    Full Text Available This study examined the effects of music genre and tempo on brain activation patterns in 10 nonmusicians.Two genres (rock and jazz and three tempos (slowed, medium/normal, andquickened were examined using EEG recording and analyzed through Fast Fourier Transform(FFT analysis. When participants listened to their preferred genre, an increase in alpha waveamplitude was observed. Alpha waves were not significantly affected by tempo. Beta waveamplitude increased significantly as the tempo increased. Genre had no effect on beta waves. Thefindings of this study indicate that genre preference and artificially modified tempo do affectalpha and beta wave activation in non-musicians listening to preselected songs.

  13. Nonlinear correlations in phase-space resolved fluctuations at drift wave frequencies

    International Nuclear Information System (INIS)

    In an effort to better understand plasma transport, we measure fluctuations associated with drift instabilities resolved in the ion phase-space. Primary attention is given to fluctuations near the electron drift frequency where there are two general components to the observed fluctuations. From two (spatial) point measurements of the ion distribution function with a variable separation along the magnetic field, a number of statistical measures of the fluctuations are calculated including cross-correlation and cross-bicoherence. Both fluid (ω/k >> vti) and kinetic (ω/k ∼ vti) components are observed in the fluctuations. The nonlinear interactions are found to depend strongly on the ion particle velocity

  14. Morning sector drift-bounce resonance driven ULF waves observed in artificially-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

    Full Text Available HF radar backscatter, which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø, has provided coherent radar ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by both the CUTLASS HF radars and the EISCAT UHF radar. Data from the SP-UK-OUCH experiment have revealed small-scale (high azimuthal wave number, m -45 waves, predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAM-MICE instrument indicate the presence of a non-Maxwellian ion distribution function. Further statistical analysis has been undertaken, using the Polar TIMAS instrument, to reveal the prevalence and magnitude of the non-Maxwellian energetic particle populations thought to be responsible for generating these wave types.

    Key words. Ionosphere (active experiments; wave-particle interactions Magnetospheric physics (MHD waves and instabilities

  15. Drift-wave spectra obtained from the theory of nonlinear ion-Landau damping in sheared magnetic field

    International Nuclear Information System (INIS)

    The local character, in poloidal mode-number space, of the resonant nonlinear interaction of drift waves with ions in a sheared magnetic field permits an analytical determination of the spectrum. Important processes underlying the stabilization are energy cascade and transfer, respectively, in ''close'' (k'/sub Theta/approx. =k/sub Theta/) and ''distant'' (k'/sub Theta/a/sub s/approx. =1/k/sub Theta/a/sub s/) interactions. The spectral index n = 4 of the high-mode-number tail is independent of the excitation mechanism

  16. Effect of parallel ion motion in three-drift-wave interaction

    International Nuclear Information System (INIS)

    The nonlinear interaction of three drift modes, including parallel ion motion, is discussed analytically and numerically. An intrinsic stochastic interaction between the fluctuating electric field and the parallel ion current is observed and the saturation level is of the expected magnitude. (orig.)

  17. Two corrections to the drift-wave kinetic equation in the context of zonal-flow physics

    CERN Document Server

    Ruiz, D E; Shi, E L; Dodin, I Y

    2016-01-01

    The drift-wave (DW) kinetic equation, that is commonly used in studies of zonal flows (ZF), excludes the exchange of enstrophy between DW and ZF and also effects beyond the geometrical-optics limit. Using the quasilinear approximation of the generalized Hasegawa--Mima model, we propose a modified theory that accounts for these effects within a wave kinetic equation (WKE) of the Wigner--Moyal type, which is commonly known in quantum mechanics. In the geometrical-optics limit, this theory features additional terms beyond the traditional WKE that ensure exact conservation of the \\textit{total} enstrophy and energy in the DW-ZF system. Numerical simulations are presented to illustrate the importance of these additional terms. The proposed theory can be viewed as a reformulation of the second-order cumulant expansion (also known as the CE2) in a more intuitive manner, namely, in terms of canonical phase-space variables.

  18. Stability of drift-cyclotron loss-cone waves in H-mode plasmas

    Science.gov (United States)

    Farmer, W. A.; Morales, G. J.

    2016-06-01

    The drift-cyclotron loss-cone mode was first studied in mirror machines. In such devices, particles with small pitch angles are not confined, creating a hole in the velocity distribution function that is a source of free energy and leads to micro-instabilities in the cyclotron-range of frequencies. In the edge region of tokamak devices operating under H-mode conditions, ion loss also occurs. In this case, gradient drift carries ions moving opposite to the plasma current preferentially into the divertor, creating a one-sided loss cone. A simple analysis shows that for the quiescent H-mode plasmas in DIII-D the critical gradient for instability is exceeded within 2 cm of the separatrix, and the maximum growth rate at the separatrix is 3  ×  107 s‑1.

  19. Hysteresis and drift of spiral waves near heterogeneities: From chemical experiments to cardiac simulations

    Science.gov (United States)

    Nakouzi, Elias; Totz, Jan Frederik; Zhang, Zhihui; Steinbock, Oliver; Engel, Harald

    2016-02-01

    Dissipative patterns in excitable reaction-diffusion systems can be strongly affected by spatial heterogeneities. Using the photosensitive Belousov-Zhabotinsky reaction, we show a hysteresis effect in the transition between free and pinned spiral rotation. The latter state involves the rotation around a disk-shaped obstacle with an impermeable and inert boundary. The transition is controlled by changes in light intensity. For permeable heterogeneities of higher excitability, we observe spiral drift along both linear and circular boundaries. Our results confirm recent theoretical predictions and, in the case of spiral drift, are further reproduced by numerical simulations with a modified Oregonator model. Additional simulations with a cardiac model show that orbital motion can also exist in anisotropic and three-dimensional systems.

  20. Measurement of helicon wave coupling for current drive and anticipated role for high beta KSTAR plasmas

    Science.gov (United States)

    Wang, S. J.; Kim, H. J.; Joung, M.; Jeong, J. H.; Kim, J. H.; Bae, Y. S.; Kwak, J. G.; Wi, H. H.; Kim, H.-S.

    2015-11-01

    Helicon wave current drive has been suggested for efficient off-axis current drive in high electron beta tokamak plasmas. Fast wave drives centrally peaking current in the frequency range up to several ion cyclotron harmonics in the present tokamaks, such as KSTAR. Increasing fast wave frequency up to LH resonance frequency at the plasma edge, the spiral propagation of wave at the outer region of plasma lengthens the wave path to the plasma center. Also, optical thickness increases with frequency. It is expected that these effects produce efficient off-axis power deposition depending on the electron beta and magnetic field pitch. A low power TWA for helicon wave was installed and tested in KSTAR tokamak which is aiming for the steady-state high beta plasma requiring off-axis current drive. The power coupling properties of TWA at various plasma conditions will be presented. In addition to the coupling efficiency, issues such as load sensitivity and unwanted slow wave coupling will be addressed. Also, the simulation of plasma performance with the combination of helicon wave current drive and other conventional heating and current drive power in KSTAR will be discussed. This work was supported by the Korean Ministry of Science, ICT and Future Planning and by R&D Program through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.

  1. Dispersive waves induced by self-defocusing temporal solitons in a beta-barium-borate crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten

    2015-01-01

    We experimentally observe dispersive waves in the anomalous dispersion regime of a beta-barium-borate (BBO) crystal, induced by a self-defocusing few-cycle temporal soliton. Together the soliton and dispersive waves form an energetic octave-spanning supercontinuum. The soliton was excited in the...... normal dispersion regime of BBO through a negative cascaded quadratic nonlinearity. Using pump wavelengths from 1.24 to 1.4 μm, dispersive waves are found from 1.9 to 2.2 μm, agreeing well with calculated resonant phasematching wavelengths due to degenerate four-wave mixing to the soliton. We also...

  2. Absorption of magnetoacoustic waves in high beta plasmas

    International Nuclear Information System (INIS)

    The oscillations of a radially inhomogeneous high-β plasma column are investigated experimentally and theoretically. The high-β plasma is produced by a theta pinch discharge. The waves are launched during the post implosion phase in the frequency range of about 1 MHz. The spatial distribution of the wave fields is determined and a high absorption is observed. The absorption of magnetoacoustic waves is an efficient mechanism to heat a plasma. It was investigated under various conditions in the past. In this paper we present theoretical and experimental investigations in the transition region from the collision dominated to the collisionless regime. In the theoretical treatment the linearised MHD-equations are used where viscous and resistive effects are included. (orig./HT)

  3. A comparison of drift wave stability in stellarator and tokamak geometry

    International Nuclear Information System (INIS)

    The influence of plasma geometry on the linear stability of electrostatic ion-temperature-gradient driven drift modes (ITG or ηi=Ln/LTi modes) is investigated. An advanced fluid model is used for the ions together with Boltzmann distributed electrons. The derived eigenvalue equation is solved numerically. A comparison is made between an H-1NF [Fusion Technol. 17, 123 (1990)] like stellarator equilibrium, a numerical tokamak equilibrium and the analytical s-α equilibrium. The numerical and the analytical tokamak are found to be in good agreement in the low inverse aspect ratio limit. The growth rates of the tokamak and stellarator are comparable whereas the modulus of the real frequency is substantially larger in the stellarator. The threshold in ηi for the stellarator is found to be somewhat larger. In addition, a stronger stabilization of the ITG mode growth is found for large εn(=Ln/R) in the stellarator case

  4. Dispersive waves induced by self-defocusing temporal solitons in a beta-barium-borate crystal.

    Science.gov (United States)

    Zhou, Binbin; Bache, Morten

    2015-09-15

    We experimentally observe dispersive waves in the anomalous dispersion regime of a beta-barium-borate (BBO) crystal, induced by a self-defocusing few-cycle temporal soliton. Together the soliton and dispersive waves form an energetic octave-spanning supercontinuum. The soliton was excited in the normal dispersion regime of BBO through a negative cascaded quadratic nonlinearity. Using pump wavelengths from 1.24 to 1.4 μm, dispersive waves are found from 1.9 to 2.2 μm, agreeing well with calculated resonant phase-matching wavelengths due to degenerate four-wave mixing to the soliton. We also observe resonant radiation from nondegenerate four-wave mixing between the soliton and a probe wave, which was formed by leaking part of the pump spectrum into the anomalous dispersion regime. We confirm the experimental results through simulations. PMID:26371910

  5. Studies of waves and instabilities using increased beta, warm ion plasmas in LAPD

    Science.gov (United States)

    Carter, Troy; Dorfman, Seth; Gekelman, Walter; Vincena, Steve; van Compernolle, Bart; Tripathi, Shreekrishna; Pribyl, Pat; Morales, George

    2015-11-01

    A new plasma source based on a Lanthanum Hexaboride (LAB6) emissive cathode has been developed and installed on the LArge Plasma Device (LAPD) at UCLA. The new source provides a much higher discharge current density (compared to the standard LAPD Barium Oxide source) resulting in a factor of ~ 50 increase in plasma density and a factor of ~ 2 - 3 increase in electron temperature. Due to the increased density the ion-electron energy exchange time is shorter in the new plasma, resulting in warm ions (measured spectroscopically to be ~ 5 - 6 eV, up from unity. Topics under investigation include the physics of Alfvén waves in increased β plasmas (dispersion and kinetic damping on ions), electromagnetic effects and magnetic transport in drift-Alfvén wave turbulence, and the excitation of ion-temperature-anisotropy driven modes such as the mirror and firehose instabilities. The capabilities of the new source will be discussed along with initial experimental resuls on electromagnetic drift-Alfvén wave turbulence and Alfvén wave propagation with increased plasma β. Supported by NSF and DOE.

  6. Analysis of stochastic particle behavior in a magnetic island due to electrostatic drift waves

    International Nuclear Information System (INIS)

    Stochastic particle motion in the magnetic island in the presence of electrostatic perturbations has been studied both numerically and analytically. By evaluating the K-S entropy, it was shown that particle orbits can be stochastic by the simultaneous effects of magnetostatic perturbation and electrostatic ones with amplitude which are not large enough to induce the orbit stochasticity alone. The generation of orbit stochasticity is due to the overlapping of sub-island formed by the E B drift driven by electrostatic perturbations and is consistent with Chirikov criterion. For the given perturbed energy, the wide region in the particle orbit can be stochastic by the electrostatic perturbations with adjacent resonance surfaces and successive mode numbers, rather than the single perturbation with large amplitude. The particle diffusion process was also analysed by evaluating the cummulants of particle displacement in time and it was shown that the process is basically the Gauss one and the higher order cummurants that the second one are appeared due to the spatial inhomogeneity of the local diffusion coefficient. (author)

  7. Mechanical design and analysis for a low beta squeezed half-wave resonator

    CERN Document Server

    He, Shoubo; Zhang, Shenghu; Yue, Weiming; Zhang, Cong; Wang, Zhijun; Wang, Ruoxu; Xu, Mengxin; Huang, Shichun; Huang, Yulu; Jiang, Tiancai; Wang, Fengfeng; Zhang, Shengxue; Zhao, Hongwei

    2013-01-01

    A superconducting half-wave resonator (HWR) of frequency=162.5 MHz and {\\beta}=0.09 has been developed at Institute of Modern Physics. Mechanical stability of the low beta HWR cavity is a big challenge in cavity design and optimization. The mechanical deformations of a radio frequency superconducting cavity could be a source of instability, both in continues wave(CW) operation or in pulsed mode. Generally, the lower beta cavities have stronger Lorentz force detuning than that of the higher beta cavities. In this paper, a basic design consideration in the stiffening structure for the detuning effect caused by helium pressure and Lorentz force has been presented. The mechanical modal analysis has been investigated with finite element method(FEM). Based on these considerations, a new stiffening structure has been promoted for the HWR cavity. The computation results concerning the frequency shift show that the low beta HWR cavity with new stiffening structure has low frequency sensitivity coefficient, Lorentz for...

  8. Phase dependent advection-diffusion in drift wave - zonal flow turbulence

    CERN Document Server

    Moradi, Sara

    2016-01-01

    In plasma turbulence theory, due to the complexity of the system with many non-linearly interacting waves, the dynamics of the phases is often disregarded and the so-called random-phase approximation (RPA) is used assuming the existence of a Chirikov-like criterion for the onset of wave stochasticity. The dynamical amplitudes are represented as complex numbers, $\\psi = \\psi_r + i\\psi_i = ae^{i\\theta}$, with the amplitudes slowly varying whereas the phases are rapidly varying and, in particular, distributed uniformly over the interval $[0;2\\pi)$. However, one could expect that the phase dynamics can play a role in the self-organisation and the formation of coherent structures. In the same manner it is also expected that the RPA falls short to take coherent interaction between phases into account. In this work therefore, we studied the role of phase dynamics and the coupling of phases between different modes on the characteristic time evolution of the turbulent. We assume a simple turbulent system where the so-...

  9. Effect of shock wave reapplication on urinary n-acetyl-beta-glucosaminidase in canine kidney

    Directory of Open Access Journals (Sweden)

    Marco A.Q.R. Fortes

    2004-04-01

    Full Text Available OBJECTIVE: Renal tubular damage can be assessed with the aid of urinary dosing of N-acetyl-beta-glucosaminidase (NAG and it is possible to demonstrate a significant correlation between shock wave and damage to renal parenchyma. The objective of this study was to assess the effect of shock wave reapplication over urinary NAG in canine kidney. MATERIALS AND METHODS: The authors submitted 10 crossbred dogs to 2 applications of 2000 shock waves in a 24-hour interval in order to assess urinary NAG values after 12, 24, 36 and 48 hours. RESULTS: Twelve hours following the first shockwave application there was an increase in NAG of 6.47 ± 5.44 u/g creatinine (p 0.05. CONCLUSION: Shock wave reapplication with a 24-hour interval did not cause any increase in urinary NAG.

  10. Low-frequency waves in a high-beta collisionless plasma Polarization, compressibility and helicity

    Science.gov (United States)

    Gary, S. P.

    1986-01-01

    This paper considers the linear theory of waves near and below the ion cyclotron frequency in an isothermal electron-ion Vlasov plasma which is isotropic, homogeneous and magnetized. Numerical solutions of the full dispersion equation for the magnetosonic/whistler and Alfven/ion cyclotron modes at beta(i) = 1.0 are presented, and the polarizations, compressibilities, helicities, ion Alfven ratios and ion cross-helicities are exhibited and compared. At sufficiently large beta(i) and theta, the angle of propagation with respect to the magnetic field, the real part of the polarization of the Alfven/ion cyclotron wave changes sign, so that, for such parameters, this mode is no longer left-hand polarized. The Alfven/ion cyclotron mode becomes more compressive as the wavenumber increases, whereas the magnetosonic/whistler becomes more compressive with increasing theta.

  11. Music genre preference and tempo alter alpha and beta waves in human non-musicians

    OpenAIRE

    Hunter Gentry; Ethan Humphries; Sebastian Pena; Aldijana Mekic; Nicole Hurless; David F Nichols

    2013-01-01

    This study examined the effects of music genre and tempo on brain activation patterns in 10 nonmusicians.Two genres (rock and jazz) and three tempos (slowed, medium/normal, andquickened) were examined using EEG recording and analyzed through Fast Fourier Transform(FFT) analysis. When participants listened to their preferred genre, an increase in alpha waveamplitude was observed. Alpha waves were not significantly affected by tempo. Beta waveamplitude increased significantly as the tempo incre...

  12. Standardized F1: a consistent measure of strength of modulation of visual responses to sine-wave drifting gratings.

    Science.gov (United States)

    Wypych, M; Wang, C; Nagy, A; Benedek, G; Dreher, B; Waleszczyk, W J

    2012-11-01

    The magnitude of spike-responses of neurons in the mammalian visual system to sine-wave luminance-contrast-modulated drifting gratings is modulated by the temporal frequency of the stimulation. However, there are serious problems with consistency and reliability of the traditionally used methods of assessment of strength of such modulation. Here we propose an intuitive and simple tool for assessment of the strength of modulations in the form of standardized F1 index, zF1. We define zF1 as the ratio of the difference between the F1 (component of amplitude spectrum of the spike-response at temporal frequency of stimulation) and the mean value of spectrum amplitudes to standard deviation along all frequencies in the spectrum. In order to assess the validity of this measure, we have: (1) examined behavior of zF1 using spike-responses to optimized drifting gratings of single neurons recorded from four 'visual' structures (area V1 of primary visual cortex, superior colliculus, suprageniculate nucleus and caudate nucleus) in the brain of commonly used visual mammal - domestic cat; (2) compared the behavior of zF1 with that of classical statistics commonly employed in the analysis of steady-state responses; (3) tested the zF1 index on simulated spike-trains generated with threshold-linear model. Our analyses indicate that zF1 is resistant to distortions due to the low spike count in responses and therefore can be particularly useful in the case of recordings from neurons with low firing rates and/or low net mean responses. While most V1 and a half of caudate neurons exhibit high zF1 indices, the majorities of collicular and suprageniculate neurons exhibit low zF1 indices. We conclude that despite the general shortcomings of measuring strength of modulation inherent in the linear system approach, zF1 can serve as a sensitive and easy to interpret tool for detection of modulation and assessment of its strength in responses of visual neurons. PMID:23000273

  13. Hurricane-induced ocean waves and stokes drift and their impacts on surface transport and dispersion in the Gulf of Mexico

    Science.gov (United States)

    Curcic, Milan; Chen, Shuyi S.; Özgökmen, Tamay M.

    2016-03-01

    Hurricane Isaac induced large surface waves and a significant change in upper ocean circulation in the Gulf of Mexico before making landfall at the Louisiana coast on 29 August 2012. Isaac was observed by 194 surface drifters during the Grand Lagrangian Deployment (GLAD). A coupled atmosphere-wave-ocean model was used to forecast hurricane impacts during GLAD. The coupled model and drifter observations provide an unprecedented opportunity to study the impacts of hurricane-induced Stokes drift on ocean surface currents. The Stokes drift induced a cyclonic (anticyclonic) rotational flow on the left (right) side of the hurricane and accounted for up to 20% of the average Lagrangian velocity. In a significant deviation from drifter measurements prior to Isaac, the scale-dependent relative diffusivity is estimated to be 6 times larger during the hurricane, which represents a deviation from Okubo's (1971) canonical results for lateral dispersion in nonhurricane conditions at the ocean surface.

  14. Resposta de plantas de beterraba (Beta vulgaris e de cenoura (Daucus carota à deriva simulada de glyphosate e clomazone Response of beetroot (Beta vulgaris and carrot (Daucus carota to simulated glyphosate and clomazone drift

    Directory of Open Access Journals (Sweden)

    R.P. Rogoli

    2008-06-01

    Full Text Available Várias espécies de hortaliças são de muita importância para a alimentação humana e tornam-se alvos da deriva de herbicidas, pois comumente são cultivadas nas proximidades de culturas como arroz, soja e milho, pulverizadas com esses produtos. Neste trabalho, objetivou-se verificar possíveis efeitos de doses reduzidas dos herbicidas glyphosate e clomazone sobre plantas de beterraba (Beta vulgaris e de cenoura (Daucus carota, em diferentes fases de desenvolvimento. As doses avaliadas dos herbicidas foram de 0, 5, 10, 15 e 20% da dose recomendada, equivalentes a 0, 63, 126, 189 e 252 g ha-1 de glyphosate e 0, 14,4, 28,8, 43,2 e 57,6 g ha-1 de clomazone, respectivamente, aplicadas aos 20, 30 e 40 dias após a emergência das culturas. Observou-se aumento no percentual de fitotoxicidade do glyphosate com o incremento na dose do herbicida, e a maior suscetibilidade ocorreu com a deriva nos estádios mais precoces, em ambas as espécies. As doses de clomazone não causaram qualquer sintoma detectável visualmente para as plantas de beterraba e de cenoura. Os resultados sugerem que o herbicida glyphosate causa injúrias às plantas de beterraba e cenoura, independentemente do estádio em que ocorre a interceptação do produto. No entanto, o herbicida clomazone não interfere no desenvolvimento inicial de plantas de beterraba e cenoura.Herbicide drift over horticultural crops is a common problem in the state of Rio Grande do Sul, mainly in areas near rice, soybean and corn fields. The objective of this research was to evaluate glyphosate and clomazone drift effects on beetroot (Beta vulgaris and carrot (Daucus carota plants. The herbicides were sprayed at three different growth stages: 20, 30 and 40 days after seedling emergence. Herbicide rates evaluated were 0, 5, 10, 15, and 20% of the label rate. The sprayed rates were 0, 63, 126, 189 and 252 g ha-1 of glyphosate and 0.0, 14.4, 28.8, 43.2 and 57.6 g ha-1 of clomazone. Glyphosate injury to

  15. Design study of a beta=0.09 high current superconducting half wave resonator

    CERN Document Server

    Zhong, Hu-Tan-Xiang; Fan, Pei-Liang; Quan, Sheng-Wen; Liu, Ke-Xin

    2016-01-01

    There's presently a growing demand for high current proton and deuteron linear accelerators based on superconducting technology to better support various fields of science. A \\b{eta}=0.09 162.5 MHz high current superconducting half wave resonator (HWR) has been designed at Peking University to accelerate 100 mA proton beam or 50 mA deuteron beam after the RFQ accelerating structure. The detailed electromagnetic design, multipacting simulation, mechanical analysis of the cavity will be given in this paper.

  16. The complex mixed Wentzel-Kramers-Brillouin-full-wave approach and its application to the two dimensional mode structure analysis of ion temperature gradient/collisionless trapped electron mode drift waves

    Science.gov (United States)

    Lu, Z. X.

    2015-05-01

    The complex mixed Wentzel-Kramers-Brillouin (WKB)-full-wave approach is applied to the 2D mode structure analysis of ion temperature gradient/collisionless trapped electron mode drift waves in tokamak plasmas. The parallel mode structure is calculated with the full-wave approach, while the radial envelope is calculated with the complex WKB method. The tilting of the global mode structure along radius is demonstrated analytically. The effects of the phase and amplitude variation of the radial envelope on the parallel mode structure are included in terms of a complex radial wave vector in the parallel mode equation. It is shown that the radial equilibrium non-uniformity leads to the asymmetry of the parallel mode structure not only in configuration space but also in spectrum space. The mixed approach provides a practical way to analyze the asymmetric component of the global mode structure due to radial equilibrium non-uniformity.

  17. The complex mixed Wentzel–Kramers–Brillouin-full-wave approach and its application to the two dimensional mode structure analysis of ion temperature gradient/collisionless trapped electron mode drift waves

    International Nuclear Information System (INIS)

    The complex mixed Wentzel–Kramers–Brillouin (WKB)-full-wave approach is applied to the 2D mode structure analysis of ion temperature gradient/collisionless trapped electron mode drift waves in tokamak plasmas. The parallel mode structure is calculated with the full-wave approach, while the radial envelope is calculated with the complex WKB method. The tilting of the global mode structure along radius is demonstrated analytically. The effects of the phase and amplitude variation of the radial envelope on the parallel mode structure are included in terms of a complex radial wave vector in the parallel mode equation. It is shown that the radial equilibrium non-uniformity leads to the asymmetry of the parallel mode structure not only in configuration space but also in spectrum space. The mixed approach provides a practical way to analyze the asymmetric component of the global mode structure due to radial equilibrium non-uniformity

  18. Drift stabilization of ballooning modes in a high-(β) LHD configuration

    International Nuclear Information System (INIS)

    Ideal MHD yields at best inconclusive predictions about the stability of the LHD heliotron for (β) ≥ 3%. We investigate the impact of the drift stabilization of ballooning modes for the inward-shifted LHD configuration (vacuum magnetic axis R0 ∼ 3.5 m). The background equilibrium is considered anisotropic in which the neutral beam ions contribute about 1/4 fraction of the total diamagnetic beta, (βdia). A drift corrected ballooning mode equation obtained from the linearized gyrokinetic equation is expanded assuming that the hot particle drifts are much larger than the mode frequency. The fast particle pressure gradients contribute weakly to both the instability drive and the diamagnetic drift stabilization (which is dominated by the thermal ion diamagnetic drifts) for (βdia) in [0, 4.8]%. In the single-fluid limit (diamagnetic drifts ignored), the thermal pressure gradients drive ballooning modes in a broad region encompassing the outer 60-90% of the plasma volume at (βdia) ∼ 4.8%. To stabilize these modes, we find that diamagnetic drift corrections must be invoked (mainly due to the thermal ions). The energetic ion diamagnetic drifts play a role only for low wave number values, kα ≤ 8. It has been verified that the fast particle drift ordering imposed by the model is amply satisfied for on-axis hot particle to thermal density Nh0/Ni0 ∼ 1% even at high (βdia).

  19. Initial Results of DC Electric Fields, Associated Plasma Drifts, Magnetic Fields, and Plasma Waves Observed on the C/NOFS Satellite

    Science.gov (United States)

    Pfaff, R.; Freudenreich, H.; Bromund, K.; Klenzing, J.; Rowland, D.; Maynard, N.

    2010-01-01

    Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. Finally, the data set includes a wide range of ELF/VLF/HF oscillations corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.

  20. Drifting and meandering of Olive Ridley Sea turtles in the Bay of Bengal: Role of oceanic Rossby waves

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, P.S.; Rao, S.A.; Sadhuram, Y.

    at 12 o N takes about 96 days to cross the Bay, while same Rossby waves takes about 184 days to cross the Bay at 18 o N. These calculations are based on long- wave theory (e.g. Philander, 1990) C r =g533c 2 /ƒ 2 cm.s -1 , where C r is Rossby wave.... This is either due to the simplicity of the linear theory or due to the fact that observed waves are composed of first and second baroclinic Rossby waves (Rao et al., 2002). The cyclonic eddy appeared between 18 o N and 19 o N in late May to late June...

  1. Design Study on Medium beta SC Half-Wave Resonator at IMP

    CERN Document Server

    Wu, An-Dong; Yue, Wei-Ming; Li, Yong-Ming; Jiang, Tian-Cai; Wang, Feng-Feng; Zhang, Sheng-Xue; Huang, Ran; He, Yuan; Zhao, Hong-Wei

    2015-01-01

    A superconducting half-wave resonator has been designed with the frequency of 325 MHz and beta of 0.51. Different geometry parameters and shapes of inner conductors (racetrack, ring-shape and elliptical-shape) were optimized to decrease the peak electromagnetic fields to obtain higher accelerating gradients and minimize the dissipated power on the cavity walls. To suppress the operation frequency shift caused by the helium pressure fluctuations and maximize the tuning ranges, the frequency shifts and mechanical properties were studied on the electric and magnetic areas separately. At the end, the helium vessel was also designed to keep the mechanical structure as robust as possible. The fabrication and test of the prototype will be completed in the beginning of 2016.

  2. Half-Wave, beta=0.43 Cavity Prototyping for a Heavy Ion Linac

    Energy Technology Data Exchange (ETDEWEB)

    Popielarski, John [Michigan State University; Compton, Chris C. [Michigan State University; Hartung, Walter [Michigan State University; Johnson, Mat [Michigan State University; Oliva, John [Michigan State University; York, R. C. [Michigan State University; Marti, Felix [Michigan State University

    2008-04-01

    A medium velocity half wave resonator has been designed and prototyped at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) for use in a heavy ion linac. The cavity is designed to provide 3.7 MV of accelerating voltage at an optimum beta = v/c = 0.53, with peak surface electric and magnetic fields of 32.5 MV/m and 79 mT, respectively. The cavity was designed for stiffness and tunability, as well as straightforward fabrication, assembly and cleaning. Measurements were performed to confirm Finite Element Analysis (FEA) predictions for modal analysis, bath pressure sensitivity, tuner stiffness and tuning range. A copper cavity prototype has been fabricated to confirm tolerances and formability. A tuner prototype has been built. The helium vessel and power coupler have been designed.

  3. Influence of Ion Nonlinear Polarization Drift and Warm Ions on Solitary Kinetic Alfvén Wave

    Institute of Scientific and Technical Information of China (English)

    DUAN Su-Ping; LI Zhong-Yuan

    2003-01-01

    Considering the effects of ion nonlinear polarization drift and warm ions, we adopt two-fluid model to results derived in this paper indicate that dip SKAW and hump SKAW both exist in a wide range in magnetosphere(for the pressure parameter β ~ 10-5 ~ 0.01, where βis the ratio of thermal pressure to magnetic pressure, i.e.region 1 > β > me/mi. These results are different from previous ones. That indicates that the effects of ion nonlinear polarization drift and warm ions are important and they cannot be neglected. The SKAW has an electric field parallel to the ambient magnetic field, which makes the SKAW take an important role in the acceleration and energization of field-aligned charged particles in magnetic plasmas. And the SKAW is also important for the heating of a local plasma.So it makes a novel physical mechanism of energy transmission possible.

  4. Approach to high stability beta limit and its control by fast wave current drive in reversed field pinch plasma

    International Nuclear Information System (INIS)

    Before the generation of steady state, dynamo-free RFP configuration by rf current driving scheme, it is necessary to find an optimum configuration into high stability beta limit against m=1 resonant resistive MHD modes and reducing nonlinearly turbulent level with less rf power. As first step to the optimization study, we are interested in partially relaxed state model (PRSM) RFP configuration, which is considered to be closer to a relaxed state at finite beta since it has force-free fields for poloidal direction with a relatively shorter characteristic length of relaxation and a relatively higher stability beta limit to m=1 resonant ideal MHD modes. The stability beta limit to m=1 resonant resistive MHD modes can be predicted to be relatively high among other RFP models and to be enhanced by the current density profile control using fast magnetosonic waves (FMW), which are accessible to high density region with strong absorption rate. (author)

  5. Multipacting Simulation on Half Wave Resonantor for Beta 0.53

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Lixin; Li, Zenghai; Ko, Kwok; /SLAC; Popielarski, John; Hartung, Walter; Holzbauer, Jeremiah; /Michigan State U., NSCL

    2011-08-12

    In the driver linac of the Facility for Rare Isotope Beams (FRIB), multipacting is an issue of concern for the superconducting resonators, which must accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. While most of the multipacting bands can be conditioned and eliminated with RF, hard multipacting barriers may prevent the resonators from reaching the design voltage. Using the ACE3P code suite, multipacting bands can be computed and analysed with the Track3P module to identify potential problems in the resonator design. This paper will present simulation results for multipacting in half-wave resonators for the FRIB driver linac. The driver linac for the Facility for Rare Isotope Beams (FRIB) will use superconducting cavities to accelerate the heavy-ion beam to a minimum energy of 200 MeV/u. The first part of the driver linac utilizes two types of Quarter Wave Resonator (QWR) accelerating cavities operating at a frequency of 80.5 MHz to increase the beam energy to 17.5 MeV/u. The second part of the driver linac uses two types of Half Wave Resonators (HWR) cavities operating at a frequency of 322 MHz, with {beta} = 0.285 and 0.53 respectively to accelerate the beam to the final energy of 200 MeV/u. Multipacting (MP) is an issue of concern for superconducting resonators which may cause prolonged processing time or limit the achievable design gradient. While most of the MP bands may be conditioned and eliminated with RF, hard multipacting barriers may prevent the resonators from reaching the design voltage. Elimination of potential MP conditions in the cavity design could significantly reduce time and cost of conditioning and commissioning the driver linac. We have utilized the Track3P code, a module of ACE3P code suite, to analyze and identify the potential MP bands in the QWR and HWR cavities for the FRIB linacs. Due to space limitations, we will present the simulation results for the beta53 HWR cavity in this paper. The MP study for the QWR

  6. Instability of coupled gravity-inertial-Rossby waves on a {beta}-plane in solar system atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    McKenzie, J.F. [KwaZulu-Natal Univ., Durban (South Africa). Astrophysics and Cosmology Research Unit, School of Mathematical Sciences; Alabama Univ., AL (United States). Dept. of Physics, CSPAR; King' s College, Cambridge (United Kingdom)

    2009-07-01

    This paper provides an analysis of the combined theory of gravity-inertial-Rossby waves on a {beta}-plane in the Boussinesq approximation. The wave equation for the system is fifth order in space and time and demonstrates how gravity-inertial waves on the one hand are coupled to Rossby waves on the other through the combined effects of {beta}-, the stratification characterized by the Vaeisaelae-Brunt frequency N, the Coriolis frequency f at a given latitude, and vertical propagation which permits buoyancy modes to interact with westward propagating Rossby waves. The corresponding dispersion equation shows that the frequency of a westward propagating gravity-inertial wave is reduced by the coupling, whereas the frequency of a Rossby wave is increased. If the coupling is sufficiently strong these two modes coalesce giving rise to an instability. The instability condition translates into a curve of critical latitude {theta}{sub c} versus effective equatorial rotational Mach number M, with the region below this curve exhibiting instability. ''Supersonic'' fast rotators are unstable in a narrow band of latitudes around the equator. For example {theta}{sub c}{proportional_to}12 for Jupiter. On the other hand slow ''subsonic'' rotators (e.g. Mercury, Venus and the Sun's Corona) are unstable at all latitudes except very close to the poles where the {beta}- effect vanishes. ''Transonic'' rotators, such as the Earth and Mars, exhibit instability within latitudes of 34 and 39 , respectively, around the Equator. Similar results pertain to Oceans. In the case of an Earth's Ocean of depth 4km say, purely westward propagating waves are unstable up to 26 about the Equator. The nonlinear evolution of this instability which feeds off rotational energy and gravitational buoyancy may play an important role in atmospheric dynamics. (orig.)

  7. Linear theory of drift instability

    International Nuclear Information System (INIS)

    Drift wave instability was studied theoretically. Low frequency waves are influenced by plasma inhomogeneity when the phase velocity of the waves perpendicular to magnetic field is comparable to the drift velocity. The low-ν plasma in a homogeneous magnetic field B parallel to z-axis was considered for the analysis, and it was assumed that the plasma density varies along X-axis. Electrostatic fluctuations were assumed. The dispersion relation of drift waves was derived from the continuity equation of ions. If Coulomb collisions or resonant particles prevent electrons from following the Boltzmann distribution, various free energy sources make the drift waves unstable. The effects of resonant particles and finite Larmor radii were examined with the Vlasov equation. The stability analysis of the drift mode in a sheared magnetic field has been one of the important objects of thermonuclear fusion researches. A model magnetic field was considered and analyzed. The stability of the drift mode in toroidal systems was studied. (Kato, T.)

  8. Doppler effect in a solid medium: Spin wave emission by a precessing domain wall drifting in spin current

    Science.gov (United States)

    Xia, Hong; Chen, Jie; Zeng, Xiaoyan; Yan, Ming

    2016-04-01

    The Doppler effect is a fundamental physical phenomenon observed for waves propagating in vacuum or various media, commonly gaseous or liquid. Here, we report on the occurrence of a Doppler effect in a solid medium. Instead of a real object, a topological soliton, i.e., a magnetic domain wall (DW) traveling in a current-carrying ferromagnetic nanowire, plays the role of the moving wave source. The Larmor precession of the DW in an external field stimulates emission of monochromatic spin waves (SWs) during its motion, which show a significant Doppler effect, comparable to the acoustic one of a train whistle. This process involves two prominent spin-transfer-torque effects simultaneously, the current-driven DW motion and the current-induced SW Doppler shift. The latter gives rise to an interesting feature, i.e., the observed SW Doppler effect appears resulting from a stationary source and a moving observer, contrary to the laboratory frame.

  9. S-parameter characterization and lumped-element modelling of millimeter-wave single-drift impact-ionization avalanche transit-time diode

    Science.gov (United States)

    Zhang, Wogong; Yamamoto, Yuji; Oehme, Michael; Matthies, Klaus; Raju, Ashraful I.; Senthil Srinivasan, V. S.; Körner, Roman; Gollhofer, Martin; Bechler, Stefan; Funk, Hannes; Tillack, Bernd; Kasper, Erich; Schulze, Jörg

    2016-04-01

    Five silicon (Si) p++-n--n++ samples were grown at various doping concentrations (1.0 × 1017-2.2 × 1017 cm-3) in an n- layer by using the reduced-pressure CVD technique. By using these samples, 30 × 2 µm2 single-drift (SD) impact-ionization avalanche transit-time (IMPATT) diodes were processed with Si-based monolithic millimeter-wave integrated circuit (SIMMWIC) technology.1 , 2 ) The samples within a small process window exhibited a large negative differential resistance at approximately the avalanche frequency, as confirmed by small-signal S-parameter characterization. A model based on depletion width was given to explain the conditions for the appearance of the negative differential IMPATT resistance, which is the basis of millimeter-wave amplifier and oscillator applications. Furthermore, a measurement-based small-signal lumped-element model was established to describe the IMPATT functionality from the circuit component aspect. This lumped-element model shows a negative differential resistance within a well-defined range in the given element parameters, which can explain the experimental observations.

  10. Comment to the note "Counting of discrete Rossby/drift wave resonant triads", arXiv:1309.0405

    CERN Document Server

    Kartashov, A

    2013-01-01

    The main purpose of this note is clarify the following misunderstanding apparent in the note arXiv:1309.0405 by M. Bustamante, U. Hayat, P. Lynch, B. Quinn; [1]: the authors erroneously assume that in the manuscript arXiv:1307.8272 by A. Kartashov and E. Kartashova, [2], resonant triads with real amplitudes are counted whereas it can be seen explicitly from the form of dynamical system that wave amplitudes are complex.

  11. Drift of Scroll Wave Filaments in an Anisotropic Model of the Left Ventricle of the Human Heart

    Science.gov (United States)

    Pravdin, Sergei; Dierckx, Hans; Markhasin, Vladimir S.; Panfilov, Alexander V.

    2015-01-01

    Scroll waves are three-dimensional vortices which occur in excitable media. Their formation in the heart results in the onset of cardiac arrhythmias, and the dynamics of their filaments determine the arrhythmia type. Most studies of filament dynamics were performed in domains with simple geometries and generic description of the anisotropy of cardiac tissue. Recently, we developed an analytical model of fibre structure and anatomy of the left ventricle (LV) of the human heart. Here, we perform a systematic study of the dynamics of scroll wave filaments for the cases of positive and negative tension in this anatomical model. We study the various possible shapes of LV and different degree of anisotropy of cardiac tissue. We show that, for positive filament tension, the final position of scroll wave filament is mainly determined by the thickness of the myocardial wall but, however, anisotropy attracts the filament to the LV apex. For negative filament tension, the filament buckles, and for most cases, tends to the apex of the heart with no or slight dependency on the thickness of the LV. We discuss the mechanisms of the observed phenomena and their implications for cardiac arrhythmias. PMID:26539486

  12. 3-dimensional Oil Drift Simulations

    Science.gov (United States)

    Wettre, C.; Reistad, M.; Hjøllo, B.Å.

    Simulation of oil drift has been an ongoing activity at the Norwegian Meteorological Institute since the 1970's. The Marine Forecasting Centre provides a 24-hour service for the Norwegian Pollution Control Authority and the oil companies operating in the Norwegian sector. The response time is 30 minutes. From 2002 the service is extended to simulation of oil drift from oil spills in deep water, using the DeepBlow model developed by SINTEF Applied Chemistry. The oil drift model can be applied both for instantaneous and continuous releases. The changes in the mass of oil and emulsion as a result of evaporation and emulsion are computed. For oil spill at deep water, hydrate formation and gas dissolution are taken into account. The properties of the oil depend on the oil type, and in the present version 64 different types of oil can be simulated. For accurate oil drift simulations it is important to have the best possible data on the atmospheric and oceanic conditions. The oil drift simulations at the Norwegian Meteorological Institute are always based on the most updated data from numerical models of the atmosphere and the ocean. The drift of the surface oil is computed from the vectorial sum of the surface current from the ocean model and the wave induced Stokes drift computed from wave energy spectra from the wave prediction model. In the new model the current distribution with depth is taken into account when calculating the drift of the dispersed oil droplets. Salinity and temperature profiles from the ocean model are needed in the DeepBlow model. The result of the oil drift simulations can be plotted on sea charts used for navigation, either as trajectory plots or particle plots showing the situation at a given time. The results can also be sent as data files to be included in the user's own GIS system.

  13. A new variable transformation technique for the nonlinear drift vortex

    International Nuclear Information System (INIS)

    The dipole vortex solution of the Hasegawa-Mima equation describing the nonlinear drift wave is a stable solitary wave which is called the modon. The profile of the modon depends on the nonlinearity of the ExB drift. In order to investigate the nonlinear drift wave more accurately, the effect of the polarization drift needs to be considered. In case of containing the effect of the polarization drift the profile of the electrostatic potential is distorted in the direction perpendicular to the ExB drift. (author)

  14. Diffuse reflection infrared Fourier transform (DRIFT) spectra and high-temperature DRIFT spectra of beta-Ni(IO3)2.4H2O, Ni(IO3)2.2H2O, Mg(OH)2, and Zn(OH)F: novel embedding materials.

    Science.gov (United States)

    Pracht, G; Weckler, B; Lutz, H D

    2003-10-01

    Diffuse reflection infrared Fourier transform (DRIFT) spectra of the hydroxides Mg(OH)2 and Zn(OH)F and the iodate hydrates beta-Ni(IO3)2.4H2O and Ni(IO3)2.2H2O have been recorded at ambient and high temperature. Spectra without shifts of the band maxima compared to those of conventional infrared transmission spectra and without inversion of the bands were obtained by dilution of the compounds to about 2-10% with an appropriate embedding material. alpha-Al2O3, TiO2, ZrO2, PbF2, MgO, BaO, ZnO, Na2SiO3, SiO2 (aerosil), and powdered copper, aluminum, and magnesium were tested as diluents for hydrates and hydroxides, especially at elevated temperatures, as alternatives for the commonly used KBr. Thus, alpha-Al2O3, PbF2, and powdered copper were established as the most favorable diluents. Using these novel embedding materials, high-temperature DRIFT spectra are obtainable at temperatures not accessible with KBr discs. Dehydration and decomposition of the iodate hydrates under study were shown by change or disappearance of the respective water bands. PMID:14639754

  15. Surface drift prediction in the Adriatic Sea using hyper-ensemble statistics on atmospheric, ocean and wave models: Uncertainties and probability distribution areas

    Science.gov (United States)

    Rixen, M.; Ferreira-Coelho, E.; Signell, R.

    2008-01-01

    Despite numerous and regular improvements in underlying models, surface drift prediction in the ocean remains a challenging task because of our yet limited understanding of all processes involved. Hence, deterministic approaches to the problem are often limited by empirical assumptions on underlying physics. Multi-model hyper-ensemble forecasts, which exploit the power of an optimal local combination of available information including ocean, atmospheric and wave models, may show superior forecasting skills when compared to individual models because they allow for local correction and/or bias removal. In this work, we explore in greater detail the potential and limitations of the hyper-ensemble method in the Adriatic Sea, using a comprehensive surface drifter database. The performance of the hyper-ensembles and the individual models are discussed by analyzing associated uncertainties and probability distribution maps. Results suggest that the stochastic method may reduce position errors significantly for 12 to 72??h forecasts and hence compete with pure deterministic approaches. ?? 2007 NATO Undersea Research Centre (NURC).

  16. Linear MHD Wave Propagation in Time-Dependent Flux Tube. III. Leaky Waves in Zero-Beta Plasma

    Science.gov (United States)

    Williamson, A.; Erdélyi, R.

    2016-01-01

    In this article, we evaluate the time-dependent wave properties and the damping rate of propagating fast magneto-hydrodynamic (MHD) waves when energy leakage into a magnetised atmosphere is considered. By considering a cold plasma, initial investigations into the evolution of MHD wave damping through this energy leakage will take place. The time-dependent governing equations have been derived previously in Williamson and Erdélyi (2014a, Solar Phys. 289, 899 - 909) and are now solved when the assumption of evanescent wave propagation in the outside of the waveguide is relaxed. The dispersion relation for leaky waves applicable to a straight magnetic field is determined in both an arbitrary tube and a thin-tube approximation. By analytically solving the dispersion relation in the thin-tube approximation, the explicit expressions for the temporal evolution of the dynamic frequency and wavenumber are determined. The damping rate is, then, obtained from the dispersion relation and is shown to decrease as the density ratio increases. By comparing the decrease in damping rate to the increase in damping for a stationary system, as shown, we aim to point out that energy leakage may not be as efficient a damping mechanism as previously thought.

  17. Dissipative drift instability in dusty plasma

    Directory of Open Access Journals (Sweden)

    Nilakshi Das

    2012-03-01

    Full Text Available An investigation has been done on the very low-frequency electrostatic drift waves in a collisional dusty plasma. The dust density gradient is taken perpendicular to the magnetic field B0⃗, which causes the drift wave. In this case, low-frequency drift instabilities can be driven by E1⃗×B0⃗ and diamagnetic drifts, where E1⃗ is the perturbed electric field. Dust charge fluctuation is also taken into consideration for our study. The dust- neutral and ion-neutral collision terms have been included in equations of motion. It is seen that the low-frequency drift instability gets damped in such a system. Both dust charging and collision of plasma particles with the neutrals may be responsible for the damping of the wave. Both analytical and numerical techniques have been used while developing the theory.

  18. Study of high-beta supra-thermal plasma events in the vicinity of magneto-hydrodynamic shock-waves

    Directory of Open Access Journals (Sweden)

    P. K. Marhavilas

    2010-01-01

    Full Text Available The ratio value – known as plasma parameter “beta” (β - of the interplanetary-plasma pressure (thermal pressure to themagnetic field’s (magnetic pressure or of their energy densities, is critical for the space plasmas and has important consequencesto their properties. Although in the scientific literature the contribution of the supra-thermal particles to the plasmapressure is generally assumed negligible, we deduced, by analyzing energetic particles and magnetic field measurementsrecorded by the Ulysses spacecraft, that in a series of events, the energy density contained in the supra-thermal tail of theparticle distribution is comparable to or even higher than the energy density of the magnetic field, creating conditions ofhigh-beta plasma. In particular, in this paper we analyze Ulysses measurements of the energy density ratio (parameter βep ofthe supra-thermal (20 keV to ~5 MeV ions’ (by the HI-SCALE instrument to the magnetic field’s (by the VHM/FGM instrumentin order to find occurrences of high-beta (βep >1 supra-thermal plasma conditions in the vicinity of interplanetaryshock-waves. These high-beta ion events are associated with energetic particle intensity enhancements which have beenproduced by reacceleration at the shock fronts.

  19. Theory for resonant ion acceleration by nonlinear magnetosonic fast and slow waves in finite beta plasmas

    International Nuclear Information System (INIS)

    A Korteweg--de Vries equation that is applicable to both the nonlinear magnetosonic fast and slow waves is derived from a two-fluid model with finite ion and electron pressures. As in the cold plasma theory, the fast wave has a critical angle theta/sub c/. For propagation angles greater than theta/sub c/ (quasiperpendicular propagation), the fast wave has a positive soliton, whereas for angles smaller than theta/sub c/, it has a negative soliton. Finite β effects decrease the value of theta/sub c/. The slow wave has a positive soliton for all angles of propagation. The magnitude of resonant ion acceleration (the v/sub p/ x B acceleration) by the nonlinear fast and slow waves is evaluated. In the fast wave, the electron pressure makes the acceleration stronger for all propagation angles. The decrease in theta/sub c/ resulting from finite β effects results in broadening of the region of strong acceleration. It is also found that fairly strong ion acceleration can occur in the nonlinear slow wave in high β plasmas. The possibility of unlimited acceleration of ions by quasiperpendicular magnetosonic fast waves is discussed

  20. Resposta de plantas de beterraba (Beta vulgaris) e de cenoura (Daucus carota) à deriva simulada de glyphosate e clomazone Response of beetroot (Beta vulgaris) and carrot (Daucus carota) to simulated glyphosate and clomazone drift

    OpenAIRE

    R.P. Rogoli; L.C. Fontana; S.S. Figueredo; J.A. Noldin

    2008-01-01

    Várias espécies de hortaliças são de muita importância para a alimentação humana e tornam-se alvos da deriva de herbicidas, pois comumente são cultivadas nas proximidades de culturas como arroz, soja e milho, pulverizadas com esses produtos. Neste trabalho, objetivou-se verificar possíveis efeitos de doses reduzidas dos herbicidas glyphosate e clomazone sobre plantas de beterraba (Beta vulgaris) e de cenoura (Daucus carota), em diferentes fases de desenvolvimento. As doses avaliadas dos herbi...

  1. The Alfven wave spectrum of analytic high-beta tokamak equilibria

    International Nuclear Information System (INIS)

    This thesis addresses a number of problems regarding the equilibrium and stability of a tokamak plasma under fusion conditions. To get insight into the geometric effects on the behaviour of the most prominent global modes, a spectral study was carried out on a class of analytic, noncircular plasma equilibria. Parallel to this work, extending a previous high-beta energy principle a variational principle is developed for the numerical determination of the Alfven spectrum of a high-beta tokamak with arbitrary cross-section. Based on the Lagrangian formalism, representations were derived for the potential and kinetic energy in terms of arbitrary, non-orthogonal flux coordinates, which can be readily implemented in a numerical programme. The method is then tested by using the analytic equilibrium as input. 85 refs.; 32 figs.; 2 tabs

  2. Rossby wave radiation by an eddy on a beta-plane: Experiments with laboratory altimetry

    International Nuclear Information System (INIS)

    Results from the laboratory experiments on the evolution of vortices (eddies) generated in a rotating tank with topographic β-effect are presented. The focus of the experiments is on the far-field flow which contains Rossby waves emitted by travelling vortices. The surface elevation and velocity fields are measured by the altimetric imaging velocimetry. The experiments are supplemented by shallow water numerical simulations as well as a linear theory which describes the Rossby wave radiation by travelling vortices. The cyclonic vortices observed in the experiments travel to the northwest and continuously radiate Rossby waves. Measurements show that initially axisymmetric vortices develop a dipolar component which enables them to perform translational motion. A pattern of alternating zonal jets to the west of the vortex is created by Rossby waves with approximately zonal crests. Energy spectra of the flows in the wavenumber space indicate that a wavenumber similar to that introduced by Rhines for turbulent flows on the β-plane can be introduced here. The wavenumber is based on the translational speed of a vortex rather than on the root-mean-square velocity of a turbulent flow. The comparison between the experiments and numerical simulations demonstrates that evolving vortices also emit inertial waves. While these essentially three-dimensional non-hydrostatic waves can be observed in the altimetric data, they are not accounted for in the shallow water simulations

  3. Rossby wave radiation by an eddy on a beta-plane: Experiments with laboratory altimetry

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Afanasyev, Y. D., E-mail: afanai@mun.ca [Memorial University of Newfoundland, St. John’s, Newfoundland A1B 3X7 (Canada)

    2015-07-15

    Results from the laboratory experiments on the evolution of vortices (eddies) generated in a rotating tank with topographic β-effect are presented. The focus of the experiments is on the far-field flow which contains Rossby waves emitted by travelling vortices. The surface elevation and velocity fields are measured by the altimetric imaging velocimetry. The experiments are supplemented by shallow water numerical simulations as well as a linear theory which describes the Rossby wave radiation by travelling vortices. The cyclonic vortices observed in the experiments travel to the northwest and continuously radiate Rossby waves. Measurements show that initially axisymmetric vortices develop a dipolar component which enables them to perform translational motion. A pattern of alternating zonal jets to the west of the vortex is created by Rossby waves with approximately zonal crests. Energy spectra of the flows in the wavenumber space indicate that a wavenumber similar to that introduced by Rhines for turbulent flows on the β-plane can be introduced here. The wavenumber is based on the translational speed of a vortex rather than on the root-mean-square velocity of a turbulent flow. The comparison between the experiments and numerical simulations demonstrates that evolving vortices also emit inertial waves. While these essentially three-dimensional non-hydrostatic waves can be observed in the altimetric data, they are not accounted for in the shallow water simulations.

  4. Drift reversal capability in helical systems

    International Nuclear Information System (INIS)

    The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta equilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments. (author)

  5. On the study of ion-acoustic solitary waves and double-layers in a drift multicomponent plasma with electron-inertia

    Indian Academy of Sciences (India)

    S N Paul; S Chattopadhyaya; S K Bhattacharya; B Bera

    2003-06-01

    Using the pseudopotential method, theoretical investigation has been made on the first-order Korteweg-deVries ion-acoustic solitons in a multicomponent plasma consisting of warm positive ions, negative ions and isothermal electrons. The effects of electron-inertia and drift motion of the ions on the amplitudes and widths of the solitons have been studied in a plasma having (H+, Cl-), (H+, O-), (He+, H-) and (He+, O-) ions. Ion-acoustic double-layers have also been investigated for such plasmas. It has been found that drift velocity and electron-inertia have significant contribution on the formation of double-layers in multicomponent plasma.

  6. Low-frequency waves in a high-beta collisionless plasma: polarization, compressibility and helicity

    International Nuclear Information System (INIS)

    The linear theory of waves near and below the ion cyclotron frequency in an isothermal electron-ion Vlasov plasma which is isotropic, homogeneous and magnetized is considered. Numerical solutions of the full dispersion equation for the magnetosonic whistler and Alfven/ion cyclotron modes at βsub(i)=1.0 are presented, and the polarizations, compressibilities, helicities, ion Alfven ratios and ion cross-helicities are exhibited and compared. At sufficiently large βsub(i) and theta, the angle of propagation with respect to the magnetic field, the real part of the polarization of the Alfven/ion cyclotron wave changes sign, so that, for such parameters, this mode is no longer left-hand polarized. The Alfven/ion cyclotron mode becomes more compressive as the wavenumber increases, whereas the magnetosonic/whistler becomes more compressive with increasing theta. At oblique propagation, the helicity of both modes approaches zero in the long-wavelength limit; in contrast, the ion cross-helicity is of order unity for the Alfven/ion cyclotron wave and decreases as theta increases for the magnetosonic/whistler mode. (author)

  7. Dependence of the relative backscatter cross section of 1-m density fluctuations in the auroral electrojet on the angle between electron drift and radar wave vector

    International Nuclear Information System (INIS)

    With the STARE radar system it is possible to measure, with high spatial and temporal resolution the electron drift velocity V/sub D/ and the relative amplitude of electron density fluctuations of 1-m wavelength in the auroral electrojet. These density fluctuations are generated by the combined effects of the two-stream and the gradient drift instabilities. We have determined the angular dependence of the backscatter intensity (which is proportional to the square of the amplitude of the density fluctuations) on the angle theta betweeen the electron drift direction and the direction from the scattering volume to the radar in the plane perpendicular to the magnetic field. We find a fluctuation minimum for theta = 900 and an increase towards theta = 00 over the whole velocity range up to 1000 m/s. This increase is small for velocities below the ion acoustic velocity C/sub N/ but reaches over 20 dB gain in the backscatter intensity (corresponding to a density fluctuation more than 10 times as great) for higher velocities. We explain that the backscatter is caused mainly by two-stream instability in the range cos theta>C/sub S//V/sub d/ and by secondary gradient drift instability elsewhere

  8. Sealed drift tube cosmic ray veto counters

    International Nuclear Information System (INIS)

    We describe a simple drift tube counter that has been used as a cosmic ray veto for the UCNA experiment, a first-ever measurement of the neutron beta-asymmetry using ultra-cold neutrons. These detectors provide an inexpensive alternative to more conventional scintillation detectors for large area cosmic ray anticoincidence detectors.

  9. The Tuning System for the HIE-ISOLDE High-Beta Quarter Wave Resonator

    CERN Document Server

    Zhang, P; Arnaudon, L; Artoos, K; Calatroni, S; Capatina, O; D'Elia, A; Kadi, Y; Mondino, I; Renaglia, T; Valuch, D; Delsolaro, W Venturini

    2014-01-01

    A new linac using superconducting quarter-wave resonators (QWR) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made of niobium sputtered on a bulk copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W on cavity walls. A tuning system is required in order to both minimize the forward power variation in beam operation and to compensate the unavoidable uncertainties in the frequency shift during the cool-down process. The tuning system has to fulfil a complex combination of RF, structural and thermal requirements. The paper presents the functional specifications and details the tuning system RF and mechanical design and simulations. The results of the tests performed on a prototype system are discussed and the industrialization strategy is presented in view of final production.

  10. Drift of dislocation tripoles under ultrasound influence.

    Science.gov (United States)

    Murzaev, R T; Bachurin, D V; Nazarov, A A

    2016-01-01

    Numerical simulations of dynamics of different stable dislocation tripoles under influence of monochromatic standing sound wave were performed. The basic conditions necessary for the drift and mutual rearrangements between dislocation structures were investigated. The dependence of the drift velocity of the dislocation tripoles as a function of the frequency and amplitude of the external influence was obtained. The results of the work can be useful in analysis of motion and self-organization of dislocation structure under ultrasound influence. PMID:26278625

  11. Transient chaotic transport in dissipative drift motion

    Science.gov (United States)

    Oyarzabal, R. S.; Szezech, J. D.; Batista, A. M.; de Souza, S. L. T.; Caldas, I. L.; Viana, R. L.; Sanjuán, M. A. F.

    2016-04-01

    We investigate chaotic particle transport in magnetised plasmas with two electrostatic drift waves. Considering dissipation in the drift motion, we verify that the removed KAM surfaces originate periodic attractors with their corresponding basins of attraction. We show that the properties of the basins depend on the dissipation and the space-averaged escape time decays exponentially when the dissipation increases. We find positive finite time Lyapunov exponents in dissipative drift motion, consequently the trajectories exhibit transient chaotic transport. These features indicate how the transient plasma transport depends on the dissipation.

  12. Drift chamber detectors

    International Nuclear Information System (INIS)

    A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

  13. The Copper Substrate Developments for the HIE-ISOLDE High-Beta Quarter Wave Resonator

    CERN Document Server

    Alberty, L; Aviles, I; Calatroni, S; Capatina, O; Foffano, G; Kadi, Y; Moyret, P; Schirm, K-M; Tardy, T; Venturini Delsolaro, W; D'Elia, A

    2013-01-01

    A new Linac using superconducting Quarter-Wave Resonators (QWRs) is under construction at CERN in the framework of the HIE-ISOLDE project. The QWRs are made by niobium sputtered on a bulk copper substrate. The working frequency at 4.5 K is 101.28 MHz and they will provide 6 MV/m accelerating gradient on the beam axis with a total maximum power dissipation of 10 W. The properties of the cavity substrate have a direct impact on the final cavity performance. The copper substrate has to ensure an optimum surface for the niobium sputtered layer. It has also to fulfil the required geometrical tolerances, the mechanical stability during operation and the thermal performance to optimally extract the RF dissipated power on cavity walls. The paper presents the mechanical design of the high β cavities. The procurement process of the copper raw material is detailed, including specifications and tests. The manufacturing sequence of the complete cavity is then explained and the structural and thermo-mechanical behaviour...

  14. Evolution with Drifting Targets

    CERN Document Server

    Kanade, Varun; Vaughan, Jennifer Wortman

    2010-01-01

    We consider the question of the stability of evolutionary algorithms to gradual changes, or drift, in the target concept. We define an algorithm to be resistant to drift if, for some inverse polynomial drift rate in the target function, it converges to accuracy 1 -- \\epsilon , with polynomial resources, and then stays within that accuracy indefinitely, except with probability \\epsilon , at any one time. We show that every evolution algorithm, in the sense of Valiant (2007; 2009), can be converted using the Correlational Query technique of Feldman (2008), into such a drift resistant algorithm. For certain evolutionary algorithms, such as for Boolean conjunctions, we give bounds on the rates of drift that they can resist. We develop some new evolution algorithms that are resistant to significant drift. In particular, we give an algorithm for evolving linear separators over the spherically symmetric distribution that is resistant to a drift rate of O(\\epsilon /n), and another algorithm over the more general prod...

  15. Hydrodynamic drift ratchet scalability

    CERN Document Server

    Herringer, James; Dorrington, Graham E; Mitchell, James G; Rosengarten, Gary

    2016-01-01

    The rectilinear "drift" of particles in a hydrodynamic drift ratchet arises from a combination of diffusive motion and particle-wall hydrodynamic interactions, and is therefore dependent on particle diffusivity, particle size, the amplitude and frequency of fluid oscillation and pore geometry. Using numerical simulations, we demonstrate that the drift velocity relative to the pore size is constant across different sized drift ratchet pores, if all the relevant non-dimensional groups (Peclet number, Strouhal number and ratio of particle to pore size) remain constant. These results clearly indicate for the first time the scaling parameters under which the drift ratchet achieves dynamic similarity, and so facilitates design, fabrication and testing of drift ratchets for experiments and eventually as commercial micro/nano fluidic separation devices.

  16. Dike/Drift Interactions

    International Nuclear Information System (INIS)

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1)

  17. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E. Gaffiney

    2004-11-23

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

  18. A silicon drift photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Avset, B.S.; Evensen, L.; Ellison, J.A.; Hall, G.; Roe, S.; Wheadon, R.; Hansen, T.E.

    1989-02-01

    A low capacitance photodiode based on the principle of the solid state drift chamber has been constructed and tested. The device is based on a cellular design with an anode at the centre of each of five cells allowing electrons liberated by ionisation to drift up to 1mm to the read out strip. Results on the performance of the detector, including leakage current, capacitance and drift properties, are presented and compared with simulations.

  19. Experiments on linear high beta helical axis stellarators to study simulated toroidal effects and Alfven-wave heating

    International Nuclear Information System (INIS)

    This paper discusses induced axial current studies in a hardcore Theta-Pinch; nonaxisymmetric RF heating of a high-Beta plasma column; formation of Axisymmetric hardcore theta pinches with notched hardcore current; and externally driven till made experiments on the high-beta Q machine field reversed configuration

  20. Dike/Drift Interactions

    International Nuclear Information System (INIS)

    This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report

  1. Abstraction of Drift Seepage

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Birkholzer

    2004-11-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package

  2. Ion tails and lower-hybrid-drift turbulence in the ELMO Bumpy Torus

    International Nuclear Information System (INIS)

    It is demonstrated that a low level of lower-hybrid-drift waves could explain the hot-ion tails observed in EBT; the tail temperature is related to the lower-hybrid-drift wave energy. The effect of these waves on the bulk ion distribution is also analyzed

  3. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

  4. Modeling concept drift

    DEFF Research Database (Denmark)

    Borchani, Hanen; Fernandez, Ana Maria Martinez; Masegosa, Andrés R.;

    2015-01-01

    An often used approach for detecting and adapting to concept drift when doing classification is to treat the data as i.i.d. and use changes in classification accuracy as an indication of concept drift. In this paper, we take a different perspective and propose a framework, based on probabilistic...... graphical models, that explicitly represents concept drift using latent variables. To ensure efficient inference and learning, we re- sort to a variational Bayes inference scheme. As a proof of concept, we demonstrate and analyze the proposed framework using synthetic data sets as well as a real financial...

  5. Experiments on linear high beta helical axis stellarators to study simulated toroidal effects and Alfven-wave heating: [Annual] progress report No. 1, February 16, 1987-November 15, 1987

    International Nuclear Information System (INIS)

    This paper discusses experiments on linear high beta helical axis stellarators. Experiments considered are: formation of linear high beta heliac plasma configurations; Alfven wave heating in a straight tube and in a linear high beat stellarator; shifted hardcore heliac studies; a system for measuring the timing of high-current switches in a pulsed high voltage fusion experiment; HBQM general refurbishment; and proposed experiment on excitation of the m = 1 tilt mode in field-reversed configurations

  6. Drift Scale THM Model

    Energy Technology Data Exchange (ETDEWEB)

    J. Rutqvist

    2004-10-07

    This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because

  7. Ionospheric vertical drift response at a mid-latitude station

    Science.gov (United States)

    Kouba, Daniel; Koucká Knížová, Petra

    2016-07-01

    equinox. In general, the detected values of the observed vertical drift are of lower magnitudes compare to low latitudes. Drift data in midlatitudes seems to be more influenced by the atmospheric waves than data in lower latitudes.

  8. Drift Degradation Analysis

    International Nuclear Information System (INIS)

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

  9. Drift Degradation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    D. Kicker

    2004-09-16

    Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

  10. SAA drift: Experimental results

    Science.gov (United States)

    Grigoryan, O. R.; Romashova, V. V.; Petrov, A. N.

    According to the paleomagnetic analysis there are variations of Earth’s magnetic field connected with magnetic moment changing. These variations affect on the South Atlantic Anomaly (SAA) location. Indeed different observations approved the existence of the SAA westward drift rate (0.1 1.0 deg/year) and northward drift rate (approximately 0.1 deg/year). In this work, we present the analysis of experimental results obtained in Scobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU) onboard different Earth’s artificial satellites (1972 2003). The fluxes of protons with energy >50 MeV, gamma quanta with energy >500 keV and neutrons with energy 0.1 1.0 MeV in the SAA region have been analyzed. The mentioned above experimental data were obtained onboard the orbital stations Salut-6 (1979), MIR (1991, 1998) and ISS (2003) by the similar experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact that the SAA drifts westward. Moreover the analysis of fluxes of electrons with energy about hundreds keV (Cosmos-484 (1972) and Active (Interkosmos-24, 1991) satellites) verified not only the SAA westward drift but northward drift also.

  11. Study and analysis of drift chamber parameters

    International Nuclear Information System (INIS)

    The present work deals mainly with drift chambers. In the first chapter a summary of drift chamber properties is presented. The information has been collected from the extensive bibliography available in this field. A very simple calculation procedure of drift chamber parameters has been developed and is presented in detail in the second chapter. Some prototypes have been made following two geometries (multidrift chamber and Z-chambers). Several installations have been used for test and calibration of these prototypes. A complete description of these installations is given in the third chapter. Cosmic rays, beta particles from a Ru106 radiactive source and a test beam in the WA (West Area) of SPS at CERN have been used for experimental purposes. The analysis and the results are described for the different setups. The experimental measurements have been used to produce a complete cell parametrization (position as function of drift time) and to obtain spatial resolution values (in the range of 200-250 um). Experimental results are in good agreement with numerical calculations. (Author)

  12. The new operational oil drift model at DNMI

    International Nuclear Information System (INIS)

    The conference paper deals with an new operational oil drift model developed at the Norwegian Meteorological Institute (DNMI). A feature which the earlier oil drift models had in common, is that the drift velocity was a set equal to a percentage of the observed or predicted wind (typically 3%); slightly deflected to the right of the direction of the wind due to the effect of earth's rotation (typically 15 degrees). The potential for improving drift predictions was realized from the experience that was drawn after the spill from the stranded oil tanker ''M/V Braer'' on the coast of one of the Shetland Islands in January 1993. Further experience from the Braer spill suggests that the computation of the mass budget for the oil was inaccurate in the previous model for oil drift at DNMI, at least for some types of oil. For this reason, an improved algorithm for calculation of the oil mass budget was developed. Thr new oil drift model, which has been operational since June 1, 1994, profits from information produced by three different types of models such as wind from atmospheric models, surface current and sea temperature from the ocean model, and Stokes' drift, significant wave height and mean wave period from the wave model. 16 refs., 6 figs

  13. An experimental study of lower-hybrid wave driven high-poloidal beta plasmas in the Versator II tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Squire, J.P.

    1993-01-01

    High poloidal beta plasma equilibria have been produced by both toroidally asymmetric and symmetric lower-hybrid rf injection in the Versator II tokamak. (Here [beta][sub p] is the ratio of the plasma pressure to the poloidal magnetic field pressure, and [epsilon] = a/R[sub 0] is the inverse aspect ratio). In both cases the plasma current was fully sustained by the rf, with the loop voltage negligibly small. The rf-created high energy electron distribution function, which provides a large fraction of plasma current and pressure in these plasmas, is studied by means of X-ray spectroscopy of the electron-ion perpendicular to the toroidal magnetic field and emission measurements at a full range of angles to the toroidal magnetic field have been carried out. For low plasma current equilibria, [beta][sub p] is enhanced, and an outward shift in major radius of the X-ray emission profile peak was observed, corresponding to a Shafranov shift of the magnetic axis. The LHCD equilibrium current profiles was determined from the X-ray emission profile. The LHCD X-ray data indicate a highly anisotropic energetic electron distribution function with a density approximately 1% of the bulk electron density at the center. The stored energy of this distribution is much larger than the bulk energy and the global energy confinement time scales in agreement with the Kaye-Goldston L-mode scaling. At high values of [beta][sub p] [approximately] 3, LHH generates nearly the same plasma current as LHCD. The LHH equilibria has a reduction of up to a factor of four in the high energy X-ray emission flux, as compared to LHCD. Modeling of the electron distribution function in the LHH case indicates that only one third of the current is carried by the high energy electrons. At lower values of [beta][sub p] [approximately] 1.5, LHH requires the assistance of a small applied loop voltage to maintain the plasma current and the high energy electrons carry a majority of the plasma current.

  14. Toroidal electron temperature gradient drive drift modes

    International Nuclear Information System (INIS)

    The electron temperature gradient in tokamak geometry is shown to drive a short wavelength lower hybrid drift wave turbulence due to the unfavorable magnetic curvature on the outside of the torus. Ballooning mode theory is used to determine the stability regimes and the complex eigenfrequencies. At wavelengths of order the electron gyroradius the polarization is electrostatic and the growth rate is greater than the electron transit time aroud the torus. At longer wavelengths of order the collisionless skin depth the polarization is electromagnetic with electromagnetic vortices producing the dominant transport. The small scale electrostatic component of the turbulence produces a small by (m/sub e/m/sub i/)/sup 1/2/ drift wave anomalous transport of both the trapped and passing electrons while the c/ω/sub pe/ scale turbulene produces a neo-Alcator type transport from the stochastic diffusion of the trapped electrons. 15 refs., 5 figs

  15. On plasma density blobs in drift turbulence

    CERN Document Server

    Krasheninnikov, S I

    2016-01-01

    By keeping nonlinear Boltzmann factor in electron density dependence on electrostatic potential it is demonstrated that large plasma density blobs, often seen in experiment inside separatrix, can exist within the framework of drift wave dynamics. The estimates show that plasma density in a blob can be ~3 times higher that average plasma density, but hardly exceeds this limit, which in a ball park is in agreement with experimental observations.

  16. Theoretical Studies of Drift-Alfven and Energetic Particle Physics in Fusion Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chen

    2005-07-06

    Nonlinear equations for the slow space-time evolution of the radial drift-wave envelope and zonal flow amplitude have been self-consistently derived for a model nonuniform tokamak equilibrium within the coherent four-wave drift wave-zonal flow modulation interaction model of Chen, Lin, and White [Phys. Plasmas 7, 3129 (2000)]. Solutions clearly demonstrate turbulence spreading due to nonlinearly dispersiveness and, consequently, the device-size dependence of the saturated wave intensities and transport coefficients.

  17. High resolution drift chambers

    International Nuclear Information System (INIS)

    High precision drift chambers capable of achieving less than or equal to 50 μm resolutions are discussed. In particular, we compare so called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an ''ultimate'' design of the vertex chamber. 50 refs., 36 figs., 6 tabs

  18. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  19. Negative Drift in Populations

    DEFF Research Database (Denmark)

    Lehre, Per Kristian

    2011-01-01

    An important step in gaining a better understanding of the stochastic dynamics of evolving populations, is the development of appropriate analytical tools. We present a new drift theorem for populations that allows properties of their long-term behaviour, e.g. the runtime of evolutionary algorithms...

  20. Dike Propagation Near Drifts

    International Nuclear Information System (INIS)

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M and O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M and O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report

  1. Dike Propagation Near Drifts

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2002-03-04

    The purpose of this Analysis and Model Report (AMR) supporting the Site Recommendation/License Application (SR/LA) for the Yucca Mountain Project is the development of elementary analyses of the interactions of a hypothetical dike with a repository drift (i.e., tunnel) and with the drift contents at the potential Yucca Mountain repository. This effort is intended to support the analysis of disruptive events for Total System Performance Assessment (TSPA). This AMR supports the Process Model Report (PMR) on disruptive events (CRWMS M&O 2000a). This purpose is documented in the development plan (DP) ''Coordinate Modeling of Dike Propagation Near Drifts Consequences for TSPA-SR/LA'' (CRWMS M&O 2000b). Evaluation of that Development Plan and the work to be conducted to prepare Interim Change Notice (ICN) 1 of this report, which now includes the design option of ''Open'' drifts, indicated that no revision to that DP was needed. These analyses are intended to provide reasonable bounds for a number of expected effects: (1) Temperature changes to the waste package from exposure to magma; (2) The gas flow available to degrade waste containers during the intrusion; (3) Movement of the waste package as it is displaced by the gas, pyroclasts and magma from the intruding dike (the number of packages damaged); (4) Movement of the backfill (Backfill is treated here as a design option); (5) The nature of the mechanics of the dike/drift interaction. These analyses serve two objectives: to provide preliminary analyses needed to support evaluation of the consequences of an intrusive event and to provide a basis for addressing some of the concerns of the Nuclear Regulatory Commission (NRC) expressed in the Igneous Activity Issue Resolution Status Report.

  2. Effect of magnetic field on light-induced ion drift

    International Nuclear Information System (INIS)

    Paper is devoted to theoretical study of the force aspect of magnetic field effect on the light-induced ion drift. One studied three-component (electrons, single-charge positive ions and neutral atoms) slightly ionized gas in the constant homogeneous magnetic field. One derived formulae describing ion drift under the effect of mobile monochromatic light wave. It was determined that in slightly ionized gas at superposition of the external magnetic field a component of light-induced ion drift speed that was transverse to the radiation propagation direction might occur. One estimates the magnetic field value when the projection of ion drift speed on radiation direction should change its sign. In this case, one may observe anomalous light-induced ion drift

  3. Style drift in private equity

    NARCIS (Netherlands)

    D. Cumming; G. Fleming; A. Schwienbacher

    2009-01-01

    We introduce the concept of style drift to private equity investment. We present theory and evidence pertaining to style drifts in terms of a fund manager's stated focus on particular stages of entrepreneurial development. We develop a model that derives conditions under which style drifts are less

  4. Narrowband frequency-drift structures in solar type IV bursts

    Science.gov (United States)

    Nishimura, Yukio; Ono, Takayuki; Tsuchiya, Fuminori; Misawa, Hiroaki; Kumamoto, Atsushi; Katoh, Yuto; Masuda, Satoshi; Miyoshi, Yoshizumi

    2013-12-01

    We have established the Zao Solar Radiospectrograph (ZSR), a new solar radio observation system, at the Zao observatory of Tohoku University, Japan. We observed narrowband fine structures with type IV bursts with ZSR on 2 and 3 November 2008. The observed fine structures are similar to fiber bursts in terms of the drift rates and the existence of emission and absorption stripes. Statistical analysis of the drift rates, however, shows that the observed fine structures are different from the ordinary fiber bursts as regards the sense and the magnitude of their drift rates. First, the observed drift rates include both positive and negative rates, whereas ordinary fiber bursts are usually characterized by negative drift rates. Second, the absolute values of the observed drift rates are tens of MHz s-1, whereas the typical drift rate of fiber bursts at 325 MHz is approximately -9 MHz s-1. In addition, all fine structures analyzed have narrow emission bands of less than 17 MHz. We also show that the observed narrowband emission features with drift rates of approximately 40 MHz s-1 can be interpreted as the propagation of whistler-mode waves, which is the same process as that underlying fiber bursts.

  5. Curvature-drift instability fails to generate pulsar radio emission

    OpenAIRE

    Kaganovich, Alexander; Lyubarsky, Yuri

    2010-01-01

    The curvature drift instability has long been considered as a viable mechanism for pulsar radio emission. We reconsidered this mechanism by finding an explicit solution describing propagation of short-wave electro-magnetic waves in a plasma flow along curved magnetic field lines. We show that even though the waves could be amplified, the amplification factor remains very close to unity therefore this mechanism is unable to generate high brightness temperature emission from initial weak fluctu...

  6. The Impact of Defects on Q0 for HIE-ISOLDE High-Beta Quarter-Wave Resonators

    CERN Document Server

    Zhang, P; Venturini Delsolari, W

    2014-01-01

    Superconducting quarter-wave resonators (QWRs) will be used in the SC linac for the HIE-ISOLDE project at CERN. The QWRs will be working at 4.5 K with an operating frequency of 101.28 MHz. The maximum dissipated power in the cavity is required to be 10 W at a gradient of 6 MV/m. The QWRs are niobium coated on copper substrates, thus the niobium film quality has a direct impact on the cavity performance. This note calculates the impact of defects on cavity Q0 at different locations on the cavity inner surface.

  7. Beta Thalassemia

    Science.gov (United States)

    ... South Asian (Indian, Pakistani, etc.), Southeast Asian and Chinese descent. 1 Beta Thalassemia ßß Normal beta globin ... then there is a 25% chance with each pregnancy that their child will inherit two abnormal beta ...

  8. Emplacement Drift System Description Document

    International Nuclear Information System (INIS)

    The Emplacement Drift System is part of the Engineered Barrier System and provides the interface between the various waste package (WP) systems and the Ground Control System. In conjunction with the various WPs, the Emplacement Drift System limits the release and transport of radionuclides from the WP to the Natural Barrier following waste emplacement. Collectively, the Emplacement Drift System consists of the structural support hardware (emplacement drift invert and WP emplacement pallet) and any performance-enhancing barriers (drip shields and invert ballast) installed or placed in the emplacement drifts. The Emplacement Drift System is entirely located within the emplacement drifts in the subsurface portion of the Monitored Geologic Repository (MGR); specifically, it is physically bounded by the Subsurface Facility System, the Ground Support System, and the Natural Barrier. The Emplacement Drift System supports the key MGR functions of limiting radionuclide release to the Natural Barrier, minimizing the likelihood of a criticality external to the WPs, limiting natural and induced environmental effects, and providing WP support. The Emplacement Drift System limits radionuclide release to the Natural Barrier by controlling the movement of radionuclides within the emplacement drift and to the Natural Barrier, and by limiting water contact with the WPs. The Emplacement Drift System provides physical support and barriers for emplaced WPs that reduce water contact. The Emplacement Drift WP spacing supports the thermal loading performance by complimenting drift layout and orientation as described in the system description document for the Subsurface Facility System. The Emplacement Drift System supports the WP and also provides an environment that aids in enhancing WP confinement performance. As part of the Engineered Barrier System, the Emplacement Drift System interfaces with the WP systems. The Emplacement Drift System also interfaces with the Natural Barrier

  9. Wave

    OpenAIRE

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for t...

  10. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  11. Non-Neutral Drift Resonance in Magnetrons

    Science.gov (United States)

    Kaup, D. J.

    2005-04-01

    We study the features of the RF fields in a magnetron, when the RF amplitude has saturated, in the nonrelativistic, electrostatic limit. In this saturated stage, the linear RF equations can be reduced to a fifth-order set of ordinary differential equations. Two modes of which are fast cyclotron modes, one mode is a fast drift wave, and the other two modes are the usual, well-known, slow magnetron modes. Here, we will study the interaction between the fast drift mode (diocotron mode) and the slow magnetron modes, at the diocotron resonance. We will also show that the fast cyclotron modes can be ignored at this resonance, and thereby can reduce the system to a third- order set of ordinary differential equations. Using multiscale techniques, we will then obtain solutions for the inner and the outer regions at the diocotron resonance, and thereby obtain the conversion and transmission rates between these three modes at the diocotron resonance.

  12. ABSTRACTION OF DRIFT SEEPAGE

    International Nuclear Information System (INIS)

    Drift seepage refers to flow of liquid water into repository emplacement drifts, where it can potentially contribute to degradation of the engineered systems and release and transport of radionuclides within the drifts. Because of these important effects, seepage into emplacement drifts is listed as a ''principal factor for the postclosure safety case'' in the screening criteria for grading of data in Attachment 1 of AP-3.15Q, Rev. 2, ''Managing Technical Product Inputs''. Abstraction refers to distillation of the essential components of a process model into a form suitable for use in total-system performance assessment (TSPA). Thus, the purpose of this analysis/model is to put the information generated by the seepage process modeling in a form appropriate for use in the TSPA for the Site Recommendation. This report also supports the Unsaturated-Zone Flow and Transport Process Model Report. The scope of the work is discussed below. This analysis/model is governed by the ''Technical Work Plan for Unsaturated Zone Flow and Transport Process Model Report'' (CRWMS MandO 2000a). Details of this activity are in Addendum A of the technical work plan. The original Work Direction and Planning Document is included as Attachment 7 of Addendum A. Note that the Work Direction and Planning Document contains tasks identified for both Performance Assessment Operations (PAO) and Natural Environment Program Operations (NEPO). Only the PAO tasks are documented here. The planning for the NEPO activities is now in Addendum D of the same technical work plan and the work is documented in a separate report (CRWMS MandO 2000b). The Project has been reorganized since the document was written. The responsible organizations in the new structure are the Performance Assessment Department and the Unsaturated Zone Department, respectively. The work plan for the seepage abstraction calls for determining an appropriate abstraction methodology, determining uncertainties in seepage, and providing

  13. Drift in toroidal configurations

    Science.gov (United States)

    Evangelidis, E. A.

    1990-12-01

    This paper considers possible mechanisms involved in amplifying the drift velocity of plasma particles, under conditions of toroidal geometry. It is shown that particles constrained to move on an axisymmetric circular spheroidal surface, develop a sinusoidal motion with a characteristic frequency which depends on the energy of the particles, the value of the isoflux surface, and the value of the general momentum. It is also shown that the incorporation of the effects of toroidal geometry in the Lorentz equation produces a nonambipolar charge-dependent particle flux amplified by a factor 2(q/epsilon) squared.

  14. The DRIFT Dark Matter Experiments

    CERN Document Server

    Daw, E; Fox, J R; Gauvreau, J -L; Ghag, C; Harmon, L J; Harton, J L; Gold, M; Lee, E R; Loomba, D; Miller, E H; Murphy, A St J; Paling, S M; Landers, J M; Phan, N; Pipe, M; Pushkin, K; Robinson, M; Sadler, S W; Snowden-Ifft, D P; Spooner, N J C; Walker, D; Warner, D

    2011-01-01

    The current status of the DRIFT (Directional Recoil Identification From Tracks) experiment at Boulby Mine is presented, including the latest limits on the WIMP spin-dependent cross-section from 1.5 kg days of running with a mixture of CS2 and CF4. Planned upgrades to DRIFT IId are detailed, along with ongoing work towards DRIFT III, which aims to be the world's first 10 m3-scale directional Dark Matter detector.

  15. Drift-Scale Radionuclide Transport

    Energy Technology Data Exchange (ETDEWEB)

    J. Houseworth

    2004-09-22

    The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water

  16. Drift-Scale Radionuclide Transport

    International Nuclear Information System (INIS)

    The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water. The invert is the structure constructed in a drift to provide the floor of the

  17. Electromagnetic effects on dynamics of high-beta filamentary structures

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonjae; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu [University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); Umansky, Maxim V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Angus, J. R. [Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States)

    2015-01-15

    The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner scrape-off layer (SOL) region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and BOUT++ simulations, it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave instability when resistivity drops below a certain value. The blobs temperature decreases in the course of its motion through the SOL and so the blob can switch from the electromagnetic to the electrostatic regime where resistive drift waves become important again.

  18. Wave-Ice interaction

    Institute of Scientific and Technical Information of China (English)

    沈奚海莉

    2001-01-01

    The growth and movement of sea ice cover are influenced by the presence of wave field. Inturn, the wave field is influenced by the presence of ice cover. Their interaction is not fully understood.In this paper, we discuss some current understanding on wave attenuation when it propagates through frag-mented ice cover, ice drift due to the wave motion, and the growth characteristics of ice cover in wave field.

  19. The KLOE drift chamber

    Energy Technology Data Exchange (ETDEWEB)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; Lucia, E. De; Robertis, G. De; Sangro, R. De; Simone, P. De; Zorzi, G. De; Dell' Agnello, S.; Denig, A.; Domenico, A. Di; Donato, C. Di; Falco, S. Di; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U.V.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P. E-mail: paolo.valente@lnf.infn.it; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y

    2001-04-01

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy K{sub L} produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm{sup 2} in size in the 12 innermost layers and 3x3 cm{sup 2} in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented.

  20. The KLOE drift chamber

    International Nuclear Information System (INIS)

    The tracking detector of the KLOE experiment is 4 m diameter, 3.3 m length drift chamber, designed to contain a large fraction of the decays of low-energy KL produced at the Frascati DAPHINE phi-factory. The chamber is made by a thin carbon fiber structure and operated with a helium-based gas mixture in order to minimise conversion of low-energy photons and multiple scattering inside the sensitive volume. The tracking information is provided by 58 layers of stereo wires defing 12,582 cells, 2x2 cm2 in size in the 12 innermost layers and 3x3 cm2 in the outer ones. Details of the chamber design, calibration procedure and tracking performances are presented

  1. Large cooling tower drift deposition

    International Nuclear Information System (INIS)

    A model for the determination of drift deposition around natural-draft cooling towers is presented. An application of the model in actual operating conditions indicates the effect of drift rate at the cooling tower outlet and weather conditions on the size and shape of wetted area. (author)

  2. Three-dimensional computation of drift Alfven turbulence

    International Nuclear Information System (INIS)

    A transcollisional, electromagnetic fluid model, incorporating the parallel heat flux as a dependent variable, is constructed to treat electron drift turbulence in the regime of tokamak edge plasma at the L-H transition. The resulting turbulence is very sensitive to the plasma beta throughout this regime, with the scaling with rising beta produced by the effect of magnetic induction to slow the Alfvenic parallel electron dynamics and thereby leave the turbulence in a more robust, non-adiabatic state. Magnetic flutter and curvature have a minor quantitative effect is strong. Transport by magnetic flutter is small compared to that by the E x B flow eddies. Fluctuation statistics show that while the turbulence shows no coherent structure, it is coupled strongly enough so that neither density nor temperature fluctuations behave as passive scalars. Both profile gradients drive the turbulence, with the total thermal energy transport varying only weakly with the gradient ratio, d log T/d log n. Scaling with magnetic shear is pronounced, with stronger shear leading to lower drive levels. Scaling with either collision frequency or magnetic curvature is weak, consistent with their weak qualitative effect. The result is that electron drift turbulence at L-H transition edge parameters is drift Alfven turbulence, with both ballooning and resistivity in a clear secondary role. The contents of the drift Alfven model will form a significant part of any useful first-principles computation of tokamak edge turbulence. (Author)

  3. DRIFT EFFECTS IN HGCDTE DETECTORS

    Directory of Open Access Journals (Sweden)

    B. PAVAN KUMAR

    2013-08-01

    Full Text Available The characteristics of temporal drift in spectral responsivity of HgCdTe photodetectors is investigated and found to have an origin different from what has been reported in literature. Traditionally, the literature attributes the cause of drift due to the deposition of thin film of ice water on the active area of the cold detector. The source of drift as proposed in this paper is more critical owing to the difficulties in acquisition of infrared temperature measurements. A model explaining the drift phenomenon in HgCdTe detectors is described by considering the deep trapping of charge carriers and generation of radiation induced deep trap centers which are meta-stable in nature. A theoretical model is fitted to the experimental data. A comparison of the model with the experimental data shows that the radiation induced deep trap centers and charge trapping effects are mainly responsible for the drift phenomenon observed in HgCdTe detectors.

  4. Kinetic Alfven solitons in a low-beta plasma

    International Nuclear Information System (INIS)

    Kinetic Alfven solitons with hot electrons and finite electron inertia in a low beta (β=8πnoT/B2G, the ratio of the kinetic to the magnetic pressure) plasma is studied analytically, with the ion motion being considered dominant through the polarization drift. Both compressive and rarefactive kinetic Alfven solitons are found to exist within a definite range of kz (the direction of propagation of the kinetic Alfven solitary waves with respect to the direction of the magnetic field) for each pair of assigned values of β and M (Mach number). Unlike in previous theoretical investigations, β appears as an explicit parameter for the kinetic Alfven solitons in this case. In addition, consideration of the electron pressure gradient is found to suppress the speed of both the Alfven solitons considerably for A (=2QM2 / βk2z, with Q the electron-to-ion mass ratio) less than unity. (Author)

  5. Surface Wave Propagation in non--ideal plasmas

    CERN Document Server

    Pandey, B P

    2015-01-01

    The properties of surface waves in a partially ionized, compressible magnetized plasma slab are investigated in this work. The waves are affected by the nonideal magnetohydrodynamic effects which causes finite drift of the magnetic field in the medium. When the magnetic field drift is ignored, the characteristics of the wave propagation in a partially ionized plasma fluid is similar to the fully ionized ideal MHD except now the propagation properties depend on the fractional ionization as well as on the compressibility of the medium. The phase velocity of the sausage and kink waves increases marginally (by a few percent) due to the compressibility of the medium in both ideal as well as Hall diffusion dominated regimes. However, unlike ideal regime, only waves below certain cut off frequency can propagate in the medium in Hall dominated regime. This cut off for a thin slab has a weak dependence on the plasma beta whereas for thick slab no such dependence exists. More importantly, since the cut off is introduce...

  6. Error sensitivity analysis of drift tube linac

    International Nuclear Information System (INIS)

    The Drift Tube Linac (DTL) is used for acceleration of protons and ions in beta range of 0.04 to 0.4. It is a RF resonating cavity excited in TM0.10 mode wherein E-field is along the axis and H-field is along azimuth. The DTL consists of array of Drift tubes which performs dual function of shielding the accelerating beam from negative RF phase and for housing the magnetic lenses for transverse focusing of the beam. The axial gaps between DTs are called acceleration gaps as particle sees E-field in this gap. The accelerating beam profile is dependent on high frequency E-field and H-field spatial distribution and static magnetic field generated by the PMQs. However the Electromagnetic fields (both static and dynamic) are expected to deviate from ideal due to fabrication tolerances and will vary during operations due to temperature fluctuations which results in mechanical deformation in the RF structures, The static magnetic field generated by PMQs will vary from PMQ to PMQ due to variation in properties of permanent magnets. This paper describes the results of sensitivity analysis on accelerating charged particle beam in Drift Tube linac due to mechanical deformations in the RF structures, variations of amplitude and phase of RF power, variation of ∫G.dl and uniformity of ∫G.dl, roll angle of PMQs and misalignment of magnetic lenses. Results obtained from simulations carried out using COMSOL, CST, Super fish and Tracewin are used to conclude effective deviations in the beam phase space and energy gain due to above mentioned factors. This analysis is carried out on 10 MeV to 20 MeV section of DTL for LEHIPA. (author)

  7. Drifting oscillations in axion monodromy

    International Nuclear Information System (INIS)

    We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

  8. Outer Belt Radial Transport Signatures in Drift Phase Structure - Case Studies

    Science.gov (United States)

    O'Brien, Paul; Green, Janet; Fennell, Joseph; Claudepierre, Seth; Roeder, James; Kwan, Betty; Mulligan Skov, Tamitha

    2016-07-01

    During geomagnetic storms, the Earth's outer radiation belt experiences enhanced radial transport. Different modes of radial transport have different temporal signatures in the particle phase-space density on timescales shorter than a drift period. We use such drift phase structure in time series particle flux observations to identify transport signatures of impulsive and oscillatory drift resonant transport. We perform multiple case studies of geomagnetic storms using particle flux taken near geostationary orbit. We estimate the radial diffusion coefficients from the drift phase structures. We show how these radial diffusion coefficients derived from particle data compare to transport coefficients deduced from wave observations.

  9. The controlled-drift detector

    CERN Document Server

    Castoldi, A; Guazzoni, C; Longoni, A; Rehak, P; Strüder, L

    2000-01-01

    A new position-sensing X-ray detector is presented. The novel device is called Controlled-Drift Detector (CDD). The detector is fully depleted and is operated by switching between integration and drift modes. The relevant details of the detector design are discussed. A complete experimental characterization of the fast readout of the integrated signal charges achievable with static drift fields in the range 100-400 V/cm has been carried out. Preliminary measurements to evaluate the charge-handling capacity are also shown. The CDD can provide unambiguous two-dimensional position measurement, high-resolution X-ray spectroscopy and time resolution below 1 ms.

  10. First forbidden beta decay in light nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Millener, D.J.; Warburton, E.K.

    1984-01-01

    Beta decay matrix elements for the operators sigma dot del and sigma dot r are calculated for eight J/sup +/ ..-->.. J/sup -/ or J/sup -/ ..-->.. J/sup +/ beta transitions. Results using harmonic oscillator wave functions differ markedly from those using more realistic Woods-Saxon wave functions. A substantial contribution to the sigma dot del matrix elements from pion exchange currents is required to reproduce the experimental beta decay rates. 15 references.

  11. First forbidden beta decay in light nuclei

    International Nuclear Information System (INIS)

    Beta decay matrix elements for the operators sigma dot del and sigma dot r are calculated for eight J+ → J- or J- → J+ beta transitions. Results using harmonic oscillator wave functions differ markedly from those using more realistic Woods-Saxon wave functions. A substantial contribution to the sigma dot del matrix elements from pion exchange currents is required to reproduce the experimental beta decay rates. 15 references

  12. Drift mode calculations for the Large Helical Device

    International Nuclear Information System (INIS)

    A fully kinetic assessment of the stability properties of toroidal drift modes has been obtained for a case for the Large Helical Device (LHD) [A.Iiyoshi, et al., Plasma Physics and Controlled Nuclear Fusion Research, 1998, Nucl.Fusion 39, 1245 (1999)]. This calculation retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. Results for toroidal drift waves destabilized by trapped particle dynamics and ion temperature gradients are presented, using three-dimensional magnetohydrodynamics equilibria reconstructed from experimental measurements. The effects of helically-trapped particles and helical curvature are investigated

  13. Drift tubes of Linac 2

    CERN Multimedia

    Photographic Service

    1977-01-01

    Being redied for installation, those at the right are for tank 1, those on the left for tank 2. Contrary to Linac 1, which had drift-tubes supported on stems, here the tubes are suspended, for better mechanical stability.

  14. Particle detection with drift chambers

    CERN Document Server

    Blum, Walter; Rolandi, Luigi

    2008-01-01

    This volume presents a thorough introduction to the theory and operation of drift chambers, one of the most important modern methods of elementary particle detection. The topics, presented in a text-book style with many illustrations, include the basics of gas ionization, by particles and by lasers, drift of electrons and ions in gases and signal creation and discuss in depth the fundamental limits of accuracy and the issue of particle identification. The book also surveys all types of drift chambers and the various drift-chamber gases in use. The calculation of the device parameters and physical processes are presented in some detail, as is all necessary background material. Thus the treatment, well beyond addressing the specialist in the field, is well suited to graduate physics students and nuclear engineers seeking a both thorough and pedagogical introduction to the field. The second edition presents a completely revised, updated and expanded version of this classic text. In particular, significantly more...

  15. Experimental method for reactor-noise measurements of effective beta

    International Nuclear Information System (INIS)

    A variance-to-mean noise technique, modified to eliminate systematic errors from drifting of reactor power, has been used to infer integral values of effective beta for uranium and plutonium fueled fast reactor modk-ups. The measurement technique, including corrections for a finite detector-electrometer time response, is described together with preliminary beta measurement results

  16. Search for neutrinoless double beta decay with DCBA

    International Nuclear Information System (INIS)

    A project called DCBA (Drift Chamber Beta-ray Analyzer) is in progress at KEK in order to search for the events of neutrinoless double beta decay. For investigating technical problems, a test apparatus called DCBA-T has been constructed. The preliminary results of its engineering run are described together with the simulation studies of backgrounds originating from 214Bi and 208Tl

  17. Diffusive shock acceleration with magnetic field amplification and Alfvenic drift

    CERN Document Server

    Kang, Hyesung

    2012-01-01

    We explore how wave-particle interactions affect diffusive shock acceleration (DSA) at astrophysical shocks by performing time-dependent kinetic simulations, in which phenomenological models for magnetic field amplification (MFA), Alfvenic drift, thermal leakage injection, Bohm-like diffusion, and a free escape boundary are implemented. If the injection fraction of cosmic-ray (CR) particles is greater than 2x10^{-4}, for the shock parameters relevant for young supernova remnants, DSA is efficient enough to develop a significant shock precursor due to CR feedback, and magnetic field can be amplified up to a factor of 20 via CR streaming instability in the upstream region. If scattering centers drift with Alfven speed in the amplified magnetic field, the CR energy spectrum can be steepened significantly and the acceleration efficiency is reduced. Nonlinear DSA with self-consistent MFA and Alfvenic drift predicts that the postshock CR pressure saturates roughly at 10 % of the shock ram pressure for strong shocks...

  18. Modelling substorm chorus events in terms of dispersive azimuthal drift

    Directory of Open Access Journals (Sweden)

    A. B. Collier

    2004-12-01

    Full Text Available The Substorm Chorus Event (SCE is a radio phenomenon observed on the ground after the onset of the substorm expansion phase. It consists of a band of VLF chorus with rising upper and lower cutoff frequencies. These emissions are thought to result from Doppler-shifted cyclotron resonance between whistler mode waves and energetic electrons which drift into a ground station's field of view from an injection site around midnight. The increasing frequency of the emission envelope has been attributed to the combined effects of energy dispersion due to gradient and curvature drifts, and the modification of resonance conditions and variation of the half-gyrofrequency cutoff resulting from the radial component of the ExB drift.

    A model is presented which accounts for the observed features of the SCE in terms of the growth rate of whistler mode waves due to anisotropy in the electron distribution. This model provides an explanation for the increasing frequency of the SCE lower cutoff, as well as reproducing the general frequency-time signature of the event. In addition, the results place some restrictions on the injected particle source distribution which might lead to a SCE.

    Key words. Space plasma physics (Wave-particle interaction – Magnetospheric physics (Plasma waves and instabilities; Storms and substorms

  19. Characteristic parameters of drift chambers calculation

    International Nuclear Information System (INIS)

    We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs

  20. Nozzle Classification for Drift Reduction in Orchard Spraying: Identification of Drift Reduction Class Threshold Nozzles

    NARCIS (Netherlands)

    Zande, van de J.C.; Holterman, H.J.; Wenneker, M.

    2008-01-01

    In fruit growing high values of spray drift are found compared to arable field applications. In arable spraying drift reducing nozzles are certified for use as drift reducing measures. The nozzles which may potentially reduce drift in fruit growing are not jet classified as drift reducing nozzles, a

  1. Atlas of Dutch drift sands

    Science.gov (United States)

    Riksen, Michel; Jungerius, Pieter

    2013-04-01

    The Netherlands is well known for its aeolian landscapes. Frequent storms during the High Middle Ages (1000-1300 AD) reactivated Pleistocene coversands and river dunes and are responsible for the formation of the Holocene drift sands at a scale which is unique for Europe. A hypothesized relationship with farmer practices for making plaggensoils has recently been refuted, because drift sand formation began centuries earlier. The coastal dune belt with their parabolic dunes dates from the same period as the drift sand. An estimate of the extent of drift sands can be made from soil maps: drift sands are too young to show much profile development (Regosols). With this method Koster estimated the maximum extent of Holocene drift sands in the Netherlands to be about 800 km2 (Koster 2005). Laser altimetry allows a more precise estimate of the total surface affected by wind from the characteristic relief patterns produced by the Holocene wind, which is different from the smooth surface of cover sand deposits. Laser altimetry has been used before to investigate the mechanism of drift sand formation (Jungerius & Riksen 2010). Most of the surface affected by wind is not active anymore, but the tell-tale rough surface survived ages of different landuse. The total affected surface amounts to 825 km2. It is noteworthy that both methods give comparable results. We recorded a total number of 367 of affected areas of varying shapes, ranging in size from 1.6 ha to a large complex of drif sands of 7,119.5 ha. As is to be expected from their mode of origin, most occurrences are associated with cover sands, and with river dunes along the river Meuse and smaller rivers in other parts of the country. Particularly the final phases of cover sand and river dunes that show more relief as parabolic dunes were affected. There are also small aeolian deposits at the lee side blown from fallow agricultural fields but they are (sub)recent. Most of the relief is irregular, but the larger

  2. In-Drift Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    D. Jolley

    2000-11-09

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses.

  3. In-Drift Microbial Communities

    International Nuclear Information System (INIS)

    As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses

  4. Experimental study of high beta toroidal plasmas

    International Nuclear Information System (INIS)

    Experiments on the Wisconsin Levitated Toroidal Octupole have produced a wide range of stable high β plasmas with β significantly above single fluid MHD theory predictions. A stable β approx. 8% plasma, twice the fluid limit, is obtained with 5 rho/sub i/ approx. L/sub n/ and tau/sub β/ approx. = 6000 tau/sub Alfven/ = 600 μsec. The enhanced stability is explained with a kinetic treatment that includes the effect of finite ion gyroradius which couples the ballooning mode to an ion drift wave. In a more collisional, large gyroradius (2 rho/sub i/ approx. L/sub n/) regime, a stable β approx. 35% plasma is obtained with a decay time of 1000 Alfven times. Measurement of the equilibrium magnetic field in this regime indicates that the diamagnetic current density is five times smaller than predicted by ideal MHD, probably due to ion gyroviscosity. Particle transport is anomalous and ranges from agreement with the classical diffusion rate at the highest beta, lowest field plasma (B/sub P/ = 200 G), to thirteen times the classical rate in a β=11%, high field plasma (B/sub P/ = 860 G) where the level of enhancement increase with magnetic field. Fluctuations in density, electrostatic potential, and magnetic field have been studied in plasmas with β from 0.1% to 40%

  5. Drift effects on electromagnetic geodesic acoustic modes

    Energy Technology Data Exchange (ETDEWEB)

    Sgalla, R. J. F., E-mail: reneesgalla@gmail.com [Institute of Physics, University of São Paulo, São Paulo 05508-900 (Brazil)

    2015-02-15

    A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the f ∼ 40 kHz oscillation observed in tokamak TCABR [Yu. K. Kuznetsov et al., Nucl. Fusion 52, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is λ{sub r} ∼ 25 cm, i.e., an order of magnitude higher than the usual value for zonal flows (ZFs)

  6. Drift effects on electromagnetic geodesic acoustic modes

    CERN Document Server

    Sgalla, Reneé J F

    2014-01-01

    A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the $f\\sim 40$ kHz oscillation observed in TCABR [Yu. K. Kuznetsov $\\textit{et al.}$, Nucl. Fusion $\\bf{52}$, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is $\\lambda_r\\sim 25$ cm, i. e., an order of magnitude higher than the usual value for zonal flows (ZFs).

  7. The CLAS drift chamber system

    CERN Document Server

    Mestayer, M D; Asavapibhop, B; Barbosa, F J; Bonneau, P; Christo, S B; Dodge, G E; Dooling, T; Duncan, W S; Dytman, S A; Feuerbach, R; Gilfoyle, G P; Gyurjyan, V; Hicks, K H; Hicks, R S; Hyde-Wright, C E; Jacobs, G; Klein, A; Klein, F J; Kossov, M; Kuhn, S E; Magahiz, R A; Major, R W; Martin, C; McGuckin, T; McNabb, J; Miskimen, R A; Müller, J A; Niczyporuk, B B; O'Meara, J E; Qin, L M; Raue, B A; Robb, J; Roudot, F; Schumacher, R A; Tedeschi, D J; Thompson, R A; Tilles, D; Tuzel, W; Vansyoc, K; Vineyard, M F; Weinstein, L B; Wilkin, G R; Yegneswaran, A; Yun, J

    2000-01-01

    Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on the toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

  8. Drift tubes of Linac 2

    CERN Multimedia

    1977-01-01

    With the advent of the 800 MeV PS Booster in 1972, the original injector of the PS, a 50 MeV Alvarez-type proton linac, had reached its limits, in terms of intensity and stability. In 1973 one therefore decided to build a new linac (Linac 2), also with a drift-tube Alvarez structure and an energy of 50 MeV. It had a new Cockcroft-Walton preinjector with 750 keV, instead of the previous one with 500 keV. Linac 2 was put into service in 1980. The old Linac 1 was then used for the study of, and later operation with, various types of ions. This picture shows Linac 2 drift-tubes, suspended on stems coming from the top, in contrast to Linac 1, where the drift-tubes stood on stems coming from the bottom.

  9. drift tube for linear accelerator

    CERN Multimedia

    A drift tube from the Linac 1. This was the first tank of the linear accelerator Linac1, the injection system for the Proton Synchrotron, It ran for 34 years (1958 - 1992). Protons entered at the far end and were accelerated between the copper drift tubes by an oscillating electromagnetic field. The field flipped 200 million times a second (200 MHz) so the protons spent 5 nanoseconds crossing a drift tube and a gap. Moving down the tank, the tubes and gaps had to get longer as the protons gained speed. The tank accelerated protons from 500 KeV to 10 MeV. Linac1 was also used to accelerate deutrons and alpha particles for the Intersecting Storage Rings and oxygen and sulpher ions for the Super Proton Synchrotron heavy ion programme.

  10. The CLAS drift chamber system

    Energy Technology Data Exchange (ETDEWEB)

    Mestayer, M.D.; Carman, D.S.; Asavaphibhop, B. [and others

    1999-04-01

    Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on a toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

  11. The CLAS drift chamber system

    International Nuclear Information System (INIS)

    Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on the toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements

  12. Characteristics of ELF/VLF drifting emissions observed at low latitude station Varanasi during geomagnetic substorms

    International Nuclear Information System (INIS)

    If the frequency within a set of periodic emissions changes significantly, the set is called drifting emissions. In this paper, characteristics of drifting ELF/VLF emissions are examined based on the ELF/VLF data recorded at low latitudes ground station Varanasi (geom. lat. 140 55/ N, long. 1540 E, L=1.07) during the period Jan., 1990 to Dec., 1990. Total seven strong events of drifting ELF/VLF emissions have been observed on 28-29 April, 1990 at pre-midnight sector out of which 3 events were analyzed in detail. The observed ELF/VLF emissions exhibit a regular frequency drifts, increasing as well as decreasing drift. The ELF/VLF emissions observed are mainly periodic emissions of rising and falling tone chorus. These emissions were observed during a geomagnetic storm period, when minimum Dst-index was -98 nT and KP-index ≥ 5. The repetition period, sweep rate and the frequency drift rate have been evaluated for all events. We have also computed the spectral power density, location of plasmapause, maximum intensity and maximum frequency attained. The generation mechanism of these drifting ELF/VLF emissions is explained in terms of a quasi-linear electron synchrotron instability model for wave excitation. The frequency drift in these emissions have been interpreted in terms of a combined effect of L-shell drift of energetic electrons and the change in convections electric field during the substorm developments. The computed maximum spectral power density of the wave varies between 1.8 x 10-21 to 4.08 x 10-22 Gauss2/Hz. The computed frequency drift rates of these drifting emissions are found in good agreement with that of experimentally observed values.

  13. Drift, Violence, and the Schools.

    Science.gov (United States)

    Besag, Frank P.

    This paper begins by discussing David Matza's concept of "Drift" as a causal factor in violence and delinquent behavior. Matza's theory of delinquency contends that youth are prone to feelings of injustice, neutralization, preparation, and desperation. According to Matza, no one characteristic of the potential delinquent is sufficient, although…

  14. Job satisfaction and preference drift.

    NARCIS (Netherlands)

    H. Maassen van den Brink; W.J.N. Groot

    1999-01-01

    Most empirical studies do not find that higher wages lead to more job satisfaction. In this paper we argue that the insignificant effect of wages on job satisfaction is due to preference drift. We adapt the standard ordered response model to allow for preference shifts. The empirical results support

  15. Drift in LED based Photometer

    DEFF Research Database (Denmark)

    Paasch, Kasper

    1999-01-01

    During the development of a low cost industrial optical sensor an unexpected drift phenomenon has shown to be critical to performance. The sensor is based on LED's as light sources and the main source of error could be tracked to the instability of the spatial radiation pattern of the LED's. This...

  16. An asymmetric outer retinal response to drifting sawtooth gratings.

    Science.gov (United States)

    Riddell, Nina; Hugrass, Laila; Jayasuriya, Jude; Crewther, Sheila G; Crewther, David P

    2016-05-01

    Electroretinogram (ERG) studies have demonstrated that the retinal response to temporally modulated fast-ON and fast-OFF sawtooth flicker is asymmetric. The response to spatiotemporal sawtooth stimuli has not yet been investigated. Perceptually, such drifting gratings or diamond plaids shaded in a sawtooth pattern appear brighter when movement produces fast-OFF relative to fast-ON luminance profiles. The neural origins of this illusion remain unclear (although a retinal basis has been suggested). Thus we presented toad eyecups with sequential epochs of sawtooth, sine-wave, and square-wave gratings drifting horizontally across the retina at temporal frequencies of 2.5-20 Hz. All ERGs revealed a sustained direct-current (DC) transtissue potential during drift and a peak at drift offset. The amplitudes of both phenomena increased with temporal frequency. Consistent with the human perceptual experience of sawtooth gratings, the sustained DC potential effect was greater for fast-OFF cf. fast-ON sawtooth. Modeling suggested that the dependence of temporal luminance contrast on stimulus device frame rate contributed to the temporal frequency effects but could not explain the divergence in response amplitudes for the two sawtooth profiles. The difference between fast-ON and fast-OFF sawtooth profiles also remained following pharmacological suppression of postreceptoral activity with tetrodotoxin (TTX), 2-amino-4-phosphonobutric acid (APB), and 2,3 cis-piperidine dicarboxylic acid (PDA). Our results indicate that the DC potential difference originates from asymmetries in the photoreceptoral response to fast-ON and fast-OFF sawtooth profiles, thus pointing to an outer retinal origin for the motion-induced drifting sawtooth brightness illusion. PMID:26888098

  17. Studies of electron drift velocity in nitrogen and isobutane

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil); Vivaldini, Tulio C.; Lima, Iara B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept. de fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

    2009-07-01

    Full text: The electron drift velocity is one of the most important transport parameters used to describe the physical behaviour of gas discharges and the development of avalanches in gaseous detectors, mainly when temporal information is significant, as in drift chambers and in the recent Resistive Plate Chambers (RPCs). Although many filling gases, isobutane is frequently used in RPCs, due to its excellent timing properties, but at high electric fields conditions there are insufficient data available in literature. In the present work we report the preliminary results related to the dependence of the electron drift velocity for isobutane as function of the reduced electric field E/N, in the range of 100 Td up to 216 Td. There are different methods to determine electron drift velocity in a gas, and our measurements were based on the Pulsed Townsend technique, which consists of extracting electrons from a metallic cathode and accelerates them toward the anode by a uniform electric field. Once the drift distance and the transit time are known, the drift velocities can be determined. In our system, the incidence of a nitrogen laser beam (LTB MNL200-LD) liberates electron from the cathode made of aluminium (40mm diameter). By means of a high voltage supply (Bertan, 225-30), these electrons are accelerated toward the anode (made of a high resistivity glass - 2:10{sup 12}{omega} cm) and this movement produces a fast electric signal in the anode, which is digitalized in an oscilloscope (LeCroy WavePro 7000) with 1 GHz bandwidth and 10 GS/s. The values obtained were compared to that ones of a Bolsig+ simulation code. In order to validate the technique and to analyze non-uniformity effects, results for nitrogen are also presented. (author)

  18. Learning under Concept Drift: an Overview

    OpenAIRE

    Žliobaitė, Indrė

    2010-01-01

    Concept drift refers to a non stationary learning problem over time. The training and the application data often mismatch in real life problems. In this report we present a context of concept drift problem 1. We focus on the issues relevant to adaptive training set formation. We present the framework and terminology, and formulate a global picture of concept drift learners design. We start with formalizing the framework for the concept drifting data in Section 1. In Section 2 we discuss the a...

  19. Line-of-Sight Path Following for Dubins Paths with Adaptive Sideslip Compensation of Drift Forces

    OpenAIRE

    Thor I. Fossen; Pettersen, Kristin Ytterstad; Galeazzi, Roberto

    2014-01-01

    We present a nonlinear adaptive path-following controller that compensates for drift forces through vehicle sideslip. Vehicle sideslip arises during path following when the vehicle is subject to drift forces caused by ocean currents, wind and waves. The proposed algorithm is motivated by a lineof-sight (LOS) guidance principle used by ancient navigators, which is here extended to path following of Dubins paths. The unknown sideslip angle is treated as a constant parameter, which is estimated ...

  20. Cosmic test of honeycomb drift chambers

    International Nuclear Information System (INIS)

    The status of the test of pokalon-C honeycomb drift chambers by cosmic rays is presented. We discuss the cosmic track reconstruction, autocalibration of drift chambers and identification of cross-talk hits. Preliminary results of the test performed for drift chambers with 5 mm cells are given

  1. Drift Chambers detectors; Detectores de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez laso, L.

    1989-07-01

    We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs.

  2. A numerical estimation of the impact of Stokes drift on upper ocean temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoshuang; WANG Zhifeng; WANG Bin; WU Kejian; HAN Guijun; LI Wei

    2014-01-01

    The impact of Stokes drift on the mixed layer temperature variation was estimated by taking into account an advective heat transport term induced by the Stokes drift in the equation of mixed layer temperature and using the oceanic and wave parameters from a global ocean circulation model (HYCOM) and a wave model ( Wave Watch III). The dimensional analysis and quantitative estimation method were conducted to assess the importance of the effect induced by the Stokes drift and to analyze its spatial distribution and seasonal variation characteristics. Results show that the contribution of the Stokes drift to the mixed layer tempera-ture variation at mid-to-high latitudes is comparable with that of the mean current, and a substantial part of mixed layer temperature change is induced by taking the Stokes drift effect into account. Although the advection heat transport induced by the Stokes drift is not the leading term for the mixed layer temperature equation, it cannot be neglected and even becomes critical in some regions for the simulation of the upper-ocean temperature.

  3. The HERMES Back Drift Chambers

    OpenAIRE

    al, S. Bernreuther et

    1998-01-01

    The tracking system of the HERMES spectrometer behind the bending magnet consists of two pairs of large planar 6-plane drift chambers. The design and performance of these chambers is described. This description comprises details on the mechanical and electronical design, information about the gas mixture used and its properties, results on alignment, calibration, resolution, and efficiencies, and a discussion of the experience gained through the first three years of operation.

  4. MPS II drift chamber system

    International Nuclear Information System (INIS)

    The MPS II detectors are narrow drift space chambers designed for high position resolution in a magnetic field and in a very high particle flux environment. Central to this implementation was the development of 3 multi-channel custom IC's and one multi-channel hybrid. The system is deadtimeless and requires no corrections on an anode-to-anode basis. Operational experience and relevance to ISABELLE detectors is discussed

  5. Broad resonances and beta-decay

    DEFF Research Database (Denmark)

    Riisager, K.; Fynbo, H. O. U.; Hyldegaard, S.;

    2015-01-01

    Beta-decay into broad resonances gives a distorted lineshape in the observed energy spectrum. Part of the distortion arises from the phase space factor, but we show that the beta-decay matrix element may also contribute. Based on a schematic model for p-wave continuum neutron states it is argued...

  6. Ion dynamics during the parametric instabilities of a left-hand polarized Alfvén wave in a proton-electron-alpha plasma

    International Nuclear Information System (INIS)

    The parametric instabilities of an Alfvén wave in a proton-electron plasma system are found to have great influence on proton dynamics, where part of the protons can be accelerated through the Landau resonance with the excited ion acoustic waves, and a beam component along the background magnetic field is formed. In this paper, with a one-dimensional hybrid simulation model, we investigate the evolution of the parametric instabilities of a monochromatic left-hand polarized Alfvén wave in a proton-electron-alpha plasma with a low beta. When the drift velocity between the protons and alpha particles is sufficiently large, the wave numbers of the backward daughter Alfvén waves can be cascaded toward higher values due to the modulational instability during the nonlinear evolution of the parametric instabilities, and the alpha particles are resonantly heated in both the parallel and perpendicular direction by the backward waves. On the other hand, when the drift velocity of alpha particles is small, the alpha particles are heated in the linear growth stage of the parametric instabilities due to the Landau resonance with the excited ion acoustic waves. Therefore, the heating occurs only in the parallel direction, and there is no obvious heating in the perpendicular direction. The relevance of our results to the preferential heating of heavy ions observed in the solar wind within 0.3 AU is also discussed in this paper.

  7. Ion dynamics during the parametric instabilities of a left-hand polarized Alfvén wave in a proton-electron-alpha plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xinliang; Lu, Quanming; Hao, Yufei; Tao, Xin; Wang, Shui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026 (China); Li, Xing, E-mail: qmlu@ustc.edu.cn [Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom)

    2014-01-01

    The parametric instabilities of an Alfvén wave in a proton-electron plasma system are found to have great influence on proton dynamics, where part of the protons can be accelerated through the Landau resonance with the excited ion acoustic waves, and a beam component along the background magnetic field is formed. In this paper, with a one-dimensional hybrid simulation model, we investigate the evolution of the parametric instabilities of a monochromatic left-hand polarized Alfvén wave in a proton-electron-alpha plasma with a low beta. When the drift velocity between the protons and alpha particles is sufficiently large, the wave numbers of the backward daughter Alfvén waves can be cascaded toward higher values due to the modulational instability during the nonlinear evolution of the parametric instabilities, and the alpha particles are resonantly heated in both the parallel and perpendicular direction by the backward waves. On the other hand, when the drift velocity of alpha particles is small, the alpha particles are heated in the linear growth stage of the parametric instabilities due to the Landau resonance with the excited ion acoustic waves. Therefore, the heating occurs only in the parallel direction, and there is no obvious heating in the perpendicular direction. The relevance of our results to the preferential heating of heavy ions observed in the solar wind within 0.3 AU is also discussed in this paper.

  8. Dispersal of invasive species by drifting

    Institute of Scientific and Technical Information of China (English)

    M.C. VAN RIEL; G. VAN DER VELDE; A. BIJ DE VAATE

    2011-01-01

    Drifting can be an effective way for aquatic organisms to disperse and colonise new areas.Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates.The present study shows that high abundances of invasive species drift in the headstream of the river Rhine.Dikerogammarus villosus and Chelicorophium curvispinum represented up to 90% of the total of drifting macroinvertebrates.Drift activity shows seasonal and diel patterns.Most species started drifting in spring and were most abundant in the water column during the summer period.Drift activity was very low during the winter period.Diel patterns were apparent; most species,including D.villosus,drifted during the night.Drifting macroinvertebrates colonised stony substrate directly from the water column.D.villosus generally colonised the substrate at night,while higher numbers of C.curvispinum colonised the substrate during the day.It is very likely that drifting functions as a dispersal mechanism for crustacean invaders.Once waterways are connected,these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range [Current Zoology 57 (6):818-827,2011].

  9. Measurement of the Drift Velocity and Transverse Diffusion of Electrons in Liquid Xenon with the EXO-200 Detector

    CERN Document Server

    :,; Barbeau, P S; Beck, D; Belov, V; Breidenbach, M; Brunner, T; Burenkov, A; Cao, G F; Cen, W R; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Danilov, M; Daugherty, S J; Daughhetee, J; Davis, J; Delaquis, S; Der Mesrobian-Kabakian, A; DeVoe, R; Didberidze, T; Dilling, J; Dolgolenko, A; Dolinski, M J; Dunford, M; Fairbank, W; Farine, J; Feyzbakhsh, S; Fierlinger, P; Fudenberg, D; Gornea, R; Graham, K; Gratta, G; Hall, C; Hughes, M; Jewell, M J; Johnson, A; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Kravitz, S; Krucken, R; Kuchenkov, A; Kumar, K S; Lan, Y; Leonard, D S; Licciardi, C; Lin, Y H; MacLellan, R; Marino, M G; Mong, B; Moore, D; Njoya, O; Nelson, R; Odian, A; Ostrovskiy, I; Piepke, A; Pocar, A; Prescott, C Y; Retiere, F; Rowson, P C; Russell, J J; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tsang, R; Twelker, K; Vuilleumier, J -L; Waite, A; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Wood, J; Yang, L; Yen, Y -R; Zeldovich, O Ya; Zettlemoyer, J

    2016-01-01

    The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the transport of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Here we present measurements of the transverse diffusion constant and drift velocity of electrons at drift fields between 20~V/cm and 615~V/cm using EXO-200 data. At the operating field of 380~V/cm EXO-200 measures a drift velocity of 1.705$_{-0.010}^{+0.014}$~mm/$\\mu$s and a transverse diffusion coefficient of 55$\\pm$4~cm$^2$/s.

  10. Micro-heterogeneity and micro-rheological properties of high-viscosity barley beta-glucan solutions studied by diffusion wave spectroscopy (DWS)

    Science.gov (United States)

    Soluble fiber ß-glucan is one of the key dietary material in healthy food products known for reducing serum cholesterol levels. The micro-structural heterogeneity and micro-rheology of high-viscosity barley ß-glucan solutions were investigated by the diffusion wave spectroscopy (DWS) technology. By ...

  11. A Stokes drift approximation based on the Phillips spectrum

    CERN Document Server

    Breivik, Øyvind; Janssen, Peter A E M

    2016-01-01

    A new approximation to the Stokes drift velocity pro?le based on the exact solution for the Phillips spectrum is explored. The pro?file is compared with the monochromatic pro?file and the recently proposed exponential integral profi?le. ERA-Interim spectra and spectra from a wave buoy in the central North Sea are used to investigate the behaviour of the profi?le. It is found that the new profi?le has a much stronger gradient near the surface and lower normalized deviation from the pro?le computed from the spectra. Based on estimates from two open-ocean locations, an average value has been estimated for a key parameter of the profi?le. Given this parameter, the profi?le can be computed from the same two parameters as the monochromatic profi?le, namely the transport and the surface Stokes drift velocity.

  12. Experimental work on drift chambers

    International Nuclear Information System (INIS)

    An experimental work made on drift chambers is described in two chapters. In the firt chapter we present the description of the experimental installation used, as well as some details on the data adquisition systems and the characteristics on three ways used for calibration proposes (cosmic muons, β radiation and test beam using SPS at CERN facilities). The second chapter describes the defferent prototypes studied. The experimental set up and the analysis are given. Some results are discussed. The magnetic field effect is also studied. (Author)

  13. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    Science.gov (United States)

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light. PMID:18084457

  14. Coherent dynamics of exciatable coupled beta-cells

    DEFF Research Database (Denmark)

    Sørensen, Mads P; Petersen, Mette Vesterager; Aslanidi, Oleg

    Propagation of excitation waves through a cluster of insulin-secreting beta-cells (a pancreatic islet of Langerhans) is modelled, and the results are related to recent image analysis experiments.......Propagation of excitation waves through a cluster of insulin-secreting beta-cells (a pancreatic islet of Langerhans) is modelled, and the results are related to recent image analysis experiments....

  15. Spiral biasing adaptor for use in Si drift detectors and Si drift detector arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zheng; Chen, Wei

    2016-07-05

    A drift detector array, preferably a silicon drift detector (SDD) array, that uses a low current biasing adaptor is disclosed. The biasing adaptor is customizable for any desired geometry of the drift detector single cell with minimum drift time of carriers. The biasing adaptor has spiral shaped ion-implants that generate the desired voltage profile. The biasing adaptor can be processed on the same wafer as the drift detector array and only one biasing adaptor chip/side is needed for one drift detector array to generate the voltage profiles on the front side and back side of the detector array.

  16. Momentum analyzers DCBA for neutrinoless double beta decay experiments

    International Nuclear Information System (INIS)

    Momentum analyzers called Drift Chamber Beta-ray Analyzer (DCBA) are being developed at KEK in order to search for neutrinoless double beta decays of nuclei. A test prototype, DCBA-T2, has been constructed to confirm the principle detecting electron tracks in a uniform magnetic field. Another prototype, DCBA-T3, is now under construction to improve the energy resolution. The test results and the present statuses of these prototypes are presented.

  17. Momentum analyzers DCBA for neutrinoless double beta decay experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Nobuhiro, E-mail: nobuhiro.ishihara@kek.j [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2010-11-01

    Momentum analyzers called Drift Chamber Beta-ray Analyzer (DCBA) are being developed at KEK in order to search for neutrinoless double beta decays of nuclei. A test prototype, DCBA-T2, has been constructed to confirm the principle detecting electron tracks in a uniform magnetic field. Another prototype, DCBA-T3, is now under construction to improve the energy resolution. The test results and the present statuses of these prototypes are presented.

  18. Radon in the DRIFT-II directional dark matter TPC: emanation, detection and mitigation

    Science.gov (United States)

    Battat, J. B. R.; Brack, J.; Daw, E.; Dorofeev, A.; Ezeribe, A. C.; Fox, J. R.; Gauvreau, J.-L.; Gold, M.; Harmon, L. J.; Harton, J. L.; Landers, J. M.; Lee, E. R.; Loomba, D.; Matthews, J. A. J.; Miller, E. H.; Monte, A.; Murphy, A. StJ.; Paling, S. M.; Phan, N.; Pipe, M.; Robinson, M.; Sadler, S. W.; Scarff, A.; Snowden-Ifft, D. P.; Spooner, N. J. C.; Telfer, S.; Walker, D.; Warner, D.; Yuriev, L.

    2014-11-01

    Radon gas emanating from materials is of interest in environmental science and also a major concern in rare event non-accelerator particle physics experiments such as dark matter and double beta decay searches, where it is a major source of background. Notable for dark matter experiments is the production of radon progeny recoils (RPRs), the low energy (~ 100 keV) recoils of radon daughter isotopes, which can mimic the signal expected from WIMP interactions. Presented here are results of measurements of radon emanation from detector materials in the 1 m3 DRIFT-II directional dark matter gas time projection chamber experiment. Construction and operation of a radon emanation facility for this work is described, along with an analysis to continuously monitor DRIFT data for the presence of internal 222Rn and 218Po. Applying this analysis to historical DRIFT data, we show how systematic substitution of detector materials for alternatives, selected by this device for low radon emanation, has resulted in a factor of ~ 10 reduction in internal radon rates. Levels are found to be consistent with the sum from separate radon emanation measurements of the internal materials and also with direct measurement using an attached alpha spectrometer. The current DRIFT detector, DRIFT-IId, is found to have sensitivity to 222Rn of 2.5 μBql-1 with current analysis efficiency, potentially opening up DRIFT technology as a new tool for sensitive radon assay of materials.

  19. PARTICLE ACCELERATION IN PLASMOID EJECTIONS DERIVED FROM RADIO DRIFTING PULSATING STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    Nishizuka, N. [National Institute of Information and Communications Technology, 4-2-1, Nukui-Kitamachi, Koganei, Tokyo 184-8795 (Japan); Karlický, M.; Bárta, M. [Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondřejov (Czech Republic); Janvier, M., E-mail: nishizuka.naoto@nict.go.jp [Department of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom)

    2015-02-01

    We report observations of slowly drifting pulsating structures (DPSs) in the 0.8-4.5 GHz frequency range of the RT4 and RT5 radio spectrographs at Ondřejov Observatory, between 2002 and 2012. We found 106 events of DPSs, which we classified into four cases: (I) single events with a constant frequency drift (12 events), (II) multiple events occurring in the same flare with constant frequency drifts (11 events), (III) single or multiple events with increasing or decreasing frequency drift rates (52 events), and (IV) complex events containing multiple events occurring at the same time in a different frequency range (31 events). Many DPSs are associated with hard X-ray (HXR) bursts (15-25 keV) and soft X-ray (SXR) gradient peaks, as they typically occurred at the beginning of HXR peaks. This indicates that DPS events are related to the processes of fast energy release and particle acceleration. Furthermore, interpreting DPSs as signatures of plasmoids, we measured their ejection velocity, their width, and their height from the DPS spectra, from which we also estimated the reconnection rate and the plasma beta. In this interpretation, constant frequency drift indicates a constant velocity of a plasmoid, and an increasing/decreasing frequency drift indicates a deceleration/acceleration of a plasmoid ejection. The reconnection rate shows a good positive correlation with the plasmoid velocity. Finally we confirmed that some DPS events show plasmoid counterparts in Solar Dynamics Observatory/Atmospheric Imaging Assembly images.

  20. Drift correction in ptychographic diffractive imaging

    International Nuclear Information System (INIS)

    X-ray ptychography is a rapidly developing phase retrieval technique that combines the experimental advantages of coherent diffractive imaging with the possibility to image extended specimens. Data collection requires imaging at several scan points with high positional accuracy, which implies susceptibility to mechanical drift. This is a well-known problem in ptychographic scans, which can reduce reconstruction quality and limit the achievable resolution. Using a simple model for positional drift, we show that a set of corrected positions can be found systematically, leading to strong improvements in the reconstruction of a Siemens star dataset severely affected by drift. - Highlights: ► Mechanical drift during ptychographic scans can be corrected afterwards. ► The reconstruction quality is significantly improved after the drift correction. ► Different drift models can be used with this approach

  1. Precision alignment of permanent magnet drift tubes

    International Nuclear Information System (INIS)

    The Lawrence Berkeley National Laboratory (LBNL) technique of drift-tube alignment has been resurrected at Los Alamos for the precision alignment of 1-cm-core drift tubes that carry high gradient rare-earth-cobalt quadrupoles. Because the quadrupoles cannot be switched off, this technique is not applicable to a drift-tube assembly, but tests indicate that individual magnetic centers can be detected with a precision of +/-0.003 mm. Methods of transferring this information to machined alignment flats on the sides of the drift-tube body are discussed. With measurements of drift tubes designed for a 100-mA, 425-MHz drift-tube linac, offsets between the geometric and magnetic axes of up to +/-0.05 mm were detected following final assembly and welding. This degree of offset is serious if not accommodated, because it represents the entire alignment tolerance for the 40-cell tank. The measurement equipment and technique are described

  2. Drift chamber tracking with neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Lindsey, C.S.; Denby, B.; Haggerty, H.

    1992-10-01

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed.

  3. Cooling tower drift: comprehensive case study

    International Nuclear Information System (INIS)

    A comprehensive experiment to study drift from mechanical drift cooling towers was conducted during June 1978 at the PG and E Pittsburg Power Plant. The data from this study will be used for validation of drift deposition models. Preliminary results show the effects of tower geometry and orientation with respect to the wind and to single- or two-tower operation. The effect of decreasing relative humidity during a test run can also be seen

  4. Drift chamber tracking with neural networks

    International Nuclear Information System (INIS)

    We discuss drift chamber tracking with a commercial log VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed

  5. Very high energy emission of Crab-like pulsars driven by the Cherenkov drift radiation

    CERN Document Server

    Osmanov, Z

    2015-01-01

    In this paper we study the generation of very high energy (VHE) emission in Crab-like pulsars driven by means of the feedback of Cherenkov drift waves on distribution of magnetospheric electrons. We have found that the unstable Cherenkov drift modes lead to the quasi-linear diffusion (QLD), keeping the pitch angles from vanishing, which in turn, maintains the synchrotron mechanism. Considering the Crab-like pulsars it has been shown that the growth rate of the Cherenkov drift instability (ChDI) is quite high, indicating high efficiency of the process. Analyzing the mechanism for the typical parameters we have found that the Cherenkov drift emission from the extreme UV to hard $X$-rays is strongly correlated with the VHE synchrotron emission in the GeV band.

  6. Very high energy emission of Crab-like pulsars driven by the Cherenkov drift radiation

    Science.gov (United States)

    Osmanov, Z.

    2016-02-01

    In this paper, we study the generation of very high energy (VHE) emission in Crab-like pulsars driven by means of the feedback of Cherenkov drift waves on distribution of magnetospheric electrons. We have found that the unstable Cherenkov drift modes lead to the quasi-linear diffusion, keeping the pitch angles from vanishing, which in turn, maintains the synchrotron mechanism. Considering the Crab-like pulsars it has been shown that the growth rate of the Cherenkov drift instability is quite high, indicating high efficiency of the process. Analysing the mechanism for the typical parameters we have found that the Cherenkov drift emission from the extreme UV to hard X-rays is strongly correlated with the VHE synchrotron emission in the GeV band.

  7. Gravitational radiation from neutron stars deformed by crustal Hall drift

    Science.gov (United States)

    Suvorov, A. G.; Mastrano, A.; Geppert, U.

    2016-07-01

    A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within ˜104-105 yr, magnetic spots with local surface field strengths ˜1014 G maintained over ≳106 yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity ɛ ˜ 10-6, even with sub-magnetar polar field strengths, after ˜105 yr. A pulsar rotating at ˜102 Hz with such ɛ is a promising gravitational wave source candidate. Since such large deformations can be caused only by a particular magnetic field configuration that penetrates the whole star and whose maximum magnetic energy is concentrated in the outer core region, gravitational wave emission observed from radio pulsars can thus inform us about the internal field structures of young neutron stars.

  8. Redshift drift in a pressure gradient cosmology

    CERN Document Server

    Balcerzak, Adam

    2012-01-01

    We derive the redshift drift formula for the inhomogeneous pressure spherically symmetric Stephani universes which are complementary to inhomogeneous density Lema\\^itre-Tolman-Bondi (LTB) models. We show that there is a clear difference between the redshift drift predictions for these two models. The Stephani models have positive drift values at small redshift and behave qualitatively as the $\\Lambda$CDM models while the drift for LTB models is always negative. This prediction can be tested in future space experiments such as E-ELT, TMT, GMT or CODEX.

  9. Seepage Model for PA Including Drift Collapse

    International Nuclear Information System (INIS)

    The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M andO 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M andO 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in niches and in the cross drift to

  10. Supersensitive avalanche silicon drift photodetector

    International Nuclear Information System (INIS)

    Physical principles of performance and main characteristics of a novel avalanche photodetector developed on the basis of MOS (metal-oxide-silicon) technology are presented. The photodetector contains a semitransparent gate electrode and a drain contact to provide a drift of multiplied charge carriers along the semiconductor surface. A high gain (more than 104) of the photocurrent was achieved due to the local negative feedback effect realized on the Si -- SiO2 boundary. Special attention is paid to the possibilities of the development of a supersensitive avalanche CCD (charge-coupled device) for the detection of individual photons in visible and ultraviolet spectral regions. The experimental results obtained with a two-element CCD prototype are discussed. (author)

  11. Drift effects in CANDU reactors

    International Nuclear Information System (INIS)

    The diffusion equation is an approximation to the transport equation which relies on the validity of Fick's law. Since this law is not explicitly integrated in the transport equation it can only be derived approximately using homogenization theories. However, such homogenization theories state that when the cell is not symmetric Fick's law breaks down due to the presence of an additional term to the neutron current, called the drift term. In fact, this term can be interpreted as a transport correction to Fick's law which tends to increase the neutron current in a direction opposite to that specified by the flux gradient. In this paper, we investigate how the presence of asymmetric liquid zone controllers will modify the flux distribution inside a CANDU core. 5 refs., 2 figs., 1 tab

  12. Phase-mixing by the guiding centre drifts of charged particles in a plasma

    International Nuclear Information System (INIS)

    Thermal dispersion of the guiding center drifts in a plasma leads to phase-mixing and kinetic damping of macroscopic plasma perturbations. A simple illustration is given by the drifts of a dilute plasma in an inhomogeneous magnetic field. This results in a substantial kinetic damping on a time scale only being slightly longer than that of the Larmor period of gyration. Similar results are likely to be obtained in more complicated situations such as those of a dense, non-dissipative, high-beta plasma, at least as far as orders of magnitude are concerned. Thus the present phase mixing effect is expected to have a substantial general influence on the dynamics and stability of macroscopic plasma perturbations in high-beta systems with strong magnetic field inhomogeneities. (author)

  13. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  14. Suppressing drift chamber diffusion without magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Martoff, C.J. E-mail: cmartoff@nimbus.temple.edu; Snowden-Ifft, D.P.; Ohnuki, T.; Spooner, N.; Lehner, M

    2000-02-01

    The spatial resolution in drift chamber detectors for ionizing radiation is limited by diffusion of the primary electrons. A strong magnetic field along the drift direction is often applied (Fancher et al., Nucl. Instr. and Meth. A 161 (1979) 383) because it suppresses the transverse diffusion, improving the resolution but at considerable increase in cost and complexity. Here we show that transverse track diffusion can be strongly suppressed without any magnetic field. This is achieved by using a gas additive which reversibly captures primary ionization electrons, forming negative ions. The ions drift with thermal energies even at very high drift fields and low pressures (E/P=28.5 V/cm torr), and the diffusion decreases with increasing drift field. Upon arrival at the avalanche region of the chamber the negative ions are efficiently stripped and ordinary avalanche gain is obtained. Using this technique, r.m.s. transverse diffusion less than 200 {mu}m has been achieved over a 15 cm drift path at 40 torr with zero magnetic field. The method can provide high spatial resolution in detectors with long drift distances and zero magnetic field. Negative ion drift chambers would be particularly useful at low pressures and in situations such as space-based or underground experiments where detector size scaleability is important and cost, space, or power constraints preclude the use of a magnetic field.

  15. TBV 361 RESOLUTION ANALYSIS: EMPLACEMENT DRIFT ORIENTATION

    International Nuclear Information System (INIS)

    The purpose of this To Be Verified/To Be Determined (TBX) resolution analysis is to release ''To Be Verified'' (TBV)-361 related to the emplacement drift orientation. The system design criterion in ''Subsurface Facility System Description Document'' (CRWMS M andO 1998a, p.9) specifies that the emplacement drift orientation relative to the dominant joint orientations should be at least 30 degrees. The specific objectives for this analysis include the following: (1) Collect and evaluate key block data developed for the repository host horizon rock mass. (2) Assess the dominant joint orientations based on available fracture data. (3) Document the maximum block size as a function of drift orientation. (4) Assess the applicability of the drift orientation/joint orientation offset criterion in the ''Subsurface Facility System Description Document'' (CRWMS M andO 1998a, p.9). (5) Consider the effects of seepage on drift orientation. (6) Verify that the viability assessment (VA) drift orientation complies with the drift orientation/joint orientation offset criterion, or provide justifications and make recommendations for modifying the VA emplacement drift layout. In addition to providing direct support to the System Description Document (SDD), the release of TBV-361 will provide support to the Repository Subsurface Design Department. The results from this activity may also provide data and information needs to support the MGR Requirements Department, the MGR Safety Assurance Department, and the Performance Assessment Organization

  16. Effect of unsteady wind on drifting snow

    Science.gov (United States)

    Cierco, F.-X.; Naaim-Bouvet, F.; Naaim, M.

    2003-04-01

    Wind is not always a steady flow. It can oscillate producing blasts. However most of the current numerical models of drifting snow are constrained by one major assumption : forcing winds are steady and uniform. Experiments done in the CSTB climatic wind tunnel (with a data acquisition frequency of 1 Hz both for wind and drifting snow) showed that drifting snow is in a state of permanent disequilibrium in the presence of fluctuating airflows : mass flux and velocity were poorly matched. However, the study of wind and drifting snow gust factors done at Col du Lac Blanc (parameters recorded every 15 min with a scan rate of 1 s) shown that the largest drifting snow episodes appear during periods of roughly constant strong wind whereas a short but strong blast does not produce significant drifting snow. In order to better understand the effect of unsteady wind on drifting snow processes, these first investigations have been completed during winter 2003 by increasing the acquisition frequency during snow storms at Col du Lac Blanc using an ultrasonic anemometer and a profile of six drifting snow acoustic sensors set up side by side.

  17. Experimental study of the Maxwell stress in electromagnetic collisional drift turbulence

    OpenAIRE

    Taheri, Nazli

    2008-01-01

    We present experimental results for magnetic field fluctuations observed in an Argon plasma column produced in Controlled Shear Decorrelation Experiment (CSDX), operated with a helicon waves source. The observed magnetic fluctuations have power spectra, spatial distributions, and parametric variations that are similar to the potential and density fluctuations, which have been previously shown to be collisional drift waves. The magnitude of the normalized magnetic field fluctuations is much sm...

  18. Impact of groyne fields on the littoral drift: A hybrid morphological modelling study

    DEFF Research Database (Denmark)

    Kristensen, S. E.; Drønen, N.; Deigaard, R.;

    2016-01-01

    the groyne length and the littoral transport on the undisturbed coastline Qgeo* is the transport occurring outside the tip of the groynes divided by the total transport. It is found that the sensitivity of the littoral drift to variations in groyne spacing and the angle, of the approaching waves, is...

  19. Saturation regime of the collisionless drift instability in a hydrogen plasma column

    International Nuclear Information System (INIS)

    The saturation regime of the collisionless drift instability is observed in a steady state hydrogen column. The steady state parameters are observed to relax around the average values. A quasilinear model is proposed to describe the dynamics of wave growth and density gradient decay

  20. FIELD INVESTIGATION OF THE DRIFT SHADOW

    Energy Technology Data Exchange (ETDEWEB)

    G.W. Su; T.J. Kneafsey

    2006-02-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

  1. FIELD INVESTIGATION OF THE DRIFT SHADOW

    International Nuclear Information System (INIS)

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

  2. Ground Control for Emplacement Drifts for LA

    International Nuclear Information System (INIS)

    The purpose of this calculation is to analyze the stability of repository emplacement drifts during the preclosure period, and to provide a final ground support method for emplacement drifts for the License Application (LA). The scope of the work includes determination of input parameter values and loads, selection of appropriate process and methods for the calculation, application of selected methods, such as empirical or analytical, to the calculation, development and execution of numerical models, and evaluation of results. Results from this calculation are limited to use for design of the emplacement drifts and the final ground support system installed in these drifts. The design of non-emplacement openings and their ground support systems is covered in the ''Ground Control for Non-Emplacement Drifts for LA'' (BSC 2004c)

  3. Waves and instabilities in plasmas

    International Nuclear Information System (INIS)

    The contents of this book are: Plasma as a Dielectric Medium; Nyquist Technique; Absolute and Convective Instabilities; Landau Damping and Phase Mixing; Particle Trapping and Breakdown of Linear Theory; Solution of Viasov Equation via Guilding-Center Transformation; Kinetic Theory of Magnetohydrodynamic Waves; Geometric Optics; Wave-Kinetic Equation; Cutoff and Resonance; Resonant Absorption; Mode Conversion; Gyrokinetic Equation; Drift Waves; Quasi-Linear Theory; Ponderomotive Force; Parametric Instabilities; Problem Sets for Homework, Midterm and Final Examinations

  4. Drift and pseudomomentum in bounded turbulent shear flows

    Science.gov (United States)

    Phillips, W. R. C.

    2015-10-01

    This paper is concerned with the evaluation of two Lagrangian measures which arise in oscillatory or fluctuating shear flows when the fluctuating field is rotational and the spectrum of wave numbers which comprise it is continuous. The measures are the drift and pseudomomentum. Phillips [J. Fluid Mech. 430, 209 (2001), 10.1017/S0022112000002858] has shown that the measures are, in such instances, succinctly expressed in terms of Lagrangian integrals of Eulerian space-time correlations. But they are difficult to interpret, and the present work begins by expressing them in a more insightful form. This is achieved by assuming the space-time correlations are separable as magnitude, determined by one-point velocity correlations, and spatial diminution. The measures then parse into terms comprised of the mean Eulerian velocity, one-point velocity correlations, and a family of integrals of spatial diminution, which in turn define a series of Lagrangian time and velocity scales. The pseudomomentum is seen to be strictly negative and related to the turbulence kinetic energy, while the drift is mixed and strongly influenced by the Reynolds stress. Both are calculated for turbulent channel flow for a range of Reynolds numbers and appear, as the Reynolds number increases, to approach a terminal form. At all Reynolds numbers studied, the pseudomomentum has a sole peak located in wall units in the low teens, while at the highest Reynolds number studied, Reτ=5200 , the drift is negative in the vicinity of that peak, positive elsewhere, and largest near the rigid boundary. In contrast, the time and velocity scales grow almost logarithmically over much of the layer. Finally, the drift and pseudomomentum are discussed in the context of coherent wall layer structures with which they are intricately linked.

  5. Field investigation of the drift shadow

    Energy Technology Data Exchange (ETDEWEB)

    Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

    2005-09-08

    A drift shadow is an area immediately beneath an undergroundvoidthat, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturatedrock predict the existence of a drift shadow, but field tests confirmingits existence have yet to be performed. Proving the existence of driftshadows and understanding their hydrologic and transport characteristicscould provide a better understanding of how contaminants move in thesubsurface if released from waste emplacement drifts such as the proposednuclear waste repository at Yucca Mountain, Nevada. We describe the fieldprogram that will be used to investigate the existence of a drift shadowand the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch,California. The location and configuration of this mine makes it anexcellent site to observe and measure drift shadow characteristics. Themine is located in a porous sandstone unit of the Domengine Formation, anapproximately 230 meter thick series of interbedded Eocene-age shales,coals, and massive-bedded sandstones. The mining method used at the minerequired the development of two parallel drifts, one above the other,driven along the strike of the mined sandstone stratum. Thisconfiguration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around theunderlying drift. The passive and active hydrologic tests to be performedare described. In the passive method, cores will be obtained in a radialpattern around a drift and will be sectioned and analyzed for in-situwater content and chemical constituents. With the active hydrologic test,water will be introduced into the upper drift of the two parallel driftsand the flow of the water will be tracked as it passes near the bottomdrift. Tensiometers, electrical resistance probes, neutron probes, andground penetrating radar may be

  6. Survey of Coherent Approximately 1 Hz Waves in Mercury's Inner Magnetosphere from MESSENGER Observations

    Science.gov (United States)

    Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Schriver, David; Solomon, Sean C.

    2012-01-01

    We summarize observations by the MESSENGER spacecraft of highly coherent waves at frequencies between 0.4 and 5 Hz in Mercury's inner magnetosphere. This survey covers the time period from 24 March to 25 September 2011, or 2.1 Mercury years. These waves typically exhibit banded harmonic structure that drifts in frequency as the spacecraft traverses the magnetic equator. The waves are seen at all magnetic local times, but their observed rate of occurrence is much less on the dayside, at least in part the result of MESSENGER's orbit. On the nightside, on average, wave power is maximum near the equator and decreases with increasing magnetic latitude, consistent with an equatorial source. When the spacecraft traverses the plasma sheet during its equatorial crossings, wave power is a factor of 2 larger than for equatorial crossings that do not cross the plasma sheet. The waves are highly transverse at large magnetic latitudes but are more compressional near the equator. However, at the equator the transverse component of these waves increases relative to the compressional component as the degree of polarization decreases. Also, there is a substantial minority of events that are transverse at all magnetic latitudes, including the equator. A few of these latter events could be interpreted as ion cyclotron waves. In general, the waves tend to be strongly linear and characterized by values of the ellipticity less than 0.3 and wave-normal angles peaked near 90 deg. Their maxima in wave power at the equator coupled with their narrow-band character suggests that these waves might be generated locally in loss cone plasma characterized by high values of the ratio beta of plasma pressure to magnetic pressure. Presumably both electromagnetic ion cyclotron waves and electromagnetic ion Bernstein waves can be generated by ion loss cone distributions. If proton beta decreases with increasing magnetic latitude along a field line, then electromagnetic ion Bernstein waves are predicted

  7. Poloidal drift enhancement for improved collisionless alpha particle confinement in stellarator configurations in the quasi-isodynamic category

    International Nuclear Information System (INIS)

    Poloidal closure of contours of the second adiabatic invariant has been reported to be an essential issue in the realization of good collisionless alpha particle confinement in stellarator configurations in the quasi-isodynamic category. This common feature is examined from a different aspect, that of the poloidal drift enhancement. This is realized by radial variation of the uniform magnetic field component with a diamagnetic effect for finite beta equilibria in the W7-X stellarator, which gives poloidal drift enhancement everywhere on a flux surface. On the other hand, the additional helicity introduced to the vacuum field in the quasi-isodynamic configuration can also enhance poloidal drift. The different methods for poloidal drift enhancement are clarified systematically on the basis of the magnetic field spectrum and the magnetic topography. (author)

  8. Field investigation of the drift shadow

    International Nuclear Information System (INIS)

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and ground

  9. Field Investigation of the Drift Shadow

    Science.gov (United States)

    Su, G. W.; Kneafsey, T. J.; Ghezzehei, T. A.; Marshall, B. D.; Cook, P. J.

    2005-12-01

    A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and

  10. DKE: a fast numerical solver for the 3-D relativistic bounce-averaged electron drift kinetic equation

    Energy Technology Data Exchange (ETDEWEB)

    Decker, J.; Peysson, Y

    2004-12-01

    A new original code for solving the 3-D relativistic and bounce-averaged electron drift kinetic equation is presented. It designed for the current drive problem in tokamak with an arbitrary magnetic equilibrium. This tool allows self-consistent calculations of the bootstrap current in presence of other external current sources. RF current drive for arbitrary type of waves may be used. Several moments of the electron distribution function are determined, like the exact and effective fractions of trapped electrons, the plasma current, absorbed RF power, runaway and magnetic ripple loss rates and non-thermal Bremsstrahlung. Advanced numerical techniques have been used to make it the first fully implicit (reverse time) 3-D solver, particularly well designed for implementation in a chain of code for realistic current drive calculations in high {beta}{sub p} plasmas. All the details of the physics background and the numerical scheme are presented, as well a some examples to illustrate main code capabilities. Several important numerical points are addressed concerning code stability and potential numerical and physical limitations. (authors)

  11. Dissipative Drift Modes in Tokamak-Type Configurations

    International Nuclear Information System (INIS)

    In a toroidal configuration with a large aspect ratio the curvature of the main field makes it possible to localize drift modes in the outer part of the plasma section. Hence we have a means of producing perturbations of considerable radial extension, whose phase velocity parallel to the magnetic field remains higher than the ion thermal velocity in spite of the shearing of the field lines. In the present study the limits of stability and the growth rate of these modes are determined as a function of collision frequency and temperature gradient on the basis of the Fokker-Planck equation. The existence of trapped electrons is necessary, and this implies an effective collision frequency less than the electron oscillation frequency along the field lines. If the collision frequency is very low, the temperature gradient has a stabilizing effect. For effective collision frequencies much higher than the drift wave frequency, the temperature gradient determines the growth rate, which decreases as the collision frequency increases. There is an intermediate regime for which the growth rate no longer depends explicitly on temperature gradient or collision frequency but is proportional to the effects of the finite Larmor radius of the ions. These modes differ from the non-localized collisional mode studied by Kadomtsev and Pogutse: the radial localization is independent of shearing and the instability region is more extensive. The authors estimate the corresponding transport coefficients and discuss continuity with the customary drift waves when the effective collision frequency is higher than the electron oscillation frequency along the field lines. (author)

  12. High-beta plasma blobs in the morningside plasma sheet

    Directory of Open Access Journals (Sweden)

    G. Haerendel

    Full Text Available Equator-S frequently encountered, i.e. on 30% of the orbits between 1 March and 17 April 1998, strong variations of the magnetic field strength of typically 5–15-min duration outside about 9RE during the late-night/early-morning hours. Very high-plasma beta values were found, varying between 1 and 10 or more. Close conjunctions between Equator-S and Geotail revealed the spatial structure of these "plasma blobs" and their lifetime. They are typically 5–10° wide in longitude and have an antisymmetric plasma or magnetic pressure distribution with respect to the equator, while being altogether low-latitude phenomena 
    (≤ 15°. They drift slowly sunward, exchange plasma across the equator and have a lifetime of at least 15–30 min. While their spatial structure may be due to some sort of mirror instability, little is known about the origin of the high-beta plasma. It is speculated that the morningside boundary layer somewhat further tailward may be the source of this plasma. This would be consistent with the preference of the plasma blobs to occur during quiet conditions, although they are also found during substorm periods. The relation to auroral phenomena in the morningside oval is uncertain. The energy deposition may be mostly too weak to generate a visible signature. However, patchy aurora remains a candidate for more disturbed periods.

    Key words. Magnetospheric physics (plasma convection; plasma sheet; plasma waves and instabilities

  13. Drift mechanism of laser-induced electron acceleration in vacuum

    Science.gov (United States)

    Morgovsky, L.

    2015-12-01

    Laser-induced electron acceleration in vacuum is possible due to the ejection of electrons from the beam as a consequence of the transverse drift orthogonal to the propagation direction. The transverse drift is derived from the general solution of the equations of motion of the electrons in the field of a plane electromagnetic wave with arbitrary polarization. It is shown that the energy gain is proportional to the square of the field strength additionally modulated by the function of the injection and ejection phases. In particular, for a linearly polarized beam this function is reduced to the squared difference between the cosines of these phases. The finite laser pulse duration restricts the range of the field strength suitable for direct electron acceleration in vacuum within certain limits. It is demonstrated that the high efficiency of energy transfer from the laser wave into the kinetic energy of the accelerated electrons demands phase matching between the electron quiver phase at the exit point and the phase of the energy transfer.

  14. Drift and proportional tracking chambers

    International Nuclear Information System (INIS)

    Many techniques have been exploited in constructing tracking chambers, particle detectors which measure the trajectories and momenta of charged particles. The particular features of high-energy interactions - charged particle multiplicities, angular correlations and complex vertex topologies, to name a few - and the experimental environment of the accelerator - event rates, background rates, and so on - accent the importance of certain detector characteristics. In high energy e+e-, anti pp and pp interactions the final states are dominated by closely collimated jets of high multiplicity, requiring good track-pair resolution in the tracking chamber. High energy particles deflect very little in limited magnetic field volumes, necessitating good spatial resolution for accurate momentum measurements. The colliding beam technique generally requires a device easily adapted to full solid-angle coverage, and the high event rates expected in some of these machines put a premium on good time resolution. Finally, the production and subsequent decays of the tau, charmed and beautiful mesons will provide multiple vertex topologies. To reconstruct these vertices reliably will require considerable improvements in spatial resolution and track-pair resolution. This lecture considers the proportional counter and its descendant, the drift chamber, as tracking chambers. Its goal is to review the physics of this device in order to understand its performance limitations and promises

  15. Solving the drift control problem

    Directory of Open Access Journals (Sweden)

    Melda Ormeci Matoglu

    2015-12-01

    Full Text Available We model the problem of managing capacity in a build-to-order environment as a Brownian drift control problem. We formulate a structured linear program that models a practical discretization of the problem and exploit a strong relationship between relative value functions and dual solutions to develop a functional lower bound for the continuous problem from a dual solution to the discrete problem. Refining the discretization proves a functional strong duality for the continuous problem. The linear programming formulation is so badly scaled, however, that solving it is beyond the capabilities of standard solvers. By demonstrating the equivalence between strongly feasible bases and deterministic unichain policies, we combinatorialize the pivoting process and by exploiting the relationship between dual solutions and relative value functions, develop a mechanism for solving the LP without ever computing its coefficients. Finally, we exploit the relationship between relative value functions and dual solutions to develop a scheme analogous to column generation for refining the discretization so as to drive the gap between the discrete approximation and the continuous problem to zero quickly while keeping the LP small. Computational studies show our scheme is much faster than simply solving a regular discretization of the problem both in terms of finding a policy with a low average cost and in terms of providing a lower bound on the optimal average cost.

  16. Wind-induced drift of objects at sea: the leeway field method

    CERN Document Server

    Breivik, Øyvind; Maisondieu, Christophe; Roth, Jens Christian; 10.1016/j.apor.2011.01.005

    2011-01-01

    A method for conducting leeway field experiments to establish the drift properties of small objects (0.1-25 m) is described. The objective is to define a standardized and unambiguous procedure for condensing the drift properties down to a set of coefficients that may be incorporated into existing stochastic trajectory forecast models for drifting objects of concern to search and rescue operations and other activities involving vessels lost at sea such as containers with hazardous material. An operational definition of the slip or wind and wave-induced motion of a drifting object relative to the ambient current is proposed. This definition taken together with a strict adherence to 10 m wind speed allows us to refer unambiguously to the leeway of a drifting object. We recommend that all objects if possible be studied using what we term the direct method, where the object's leeway is studied directly using an attached current meter. We divide drifting objects into four categories, depending on their size. For th...

  17. Drift-modeling and monitoring comparisons

    International Nuclear Information System (INIS)

    Congress is looking into the conglomeration of nuclear reactors into energy centers of limited area. Drift from cooling towers can corrode and damage structures in the immediate vicinity of the towers, cause a public nuisance if located near parking lots or high-density traffic areas, and endanger local vegetation. The estimation of salt deposition has relied primarily on predictions from a variety of models, with very few direct measurements. One of the major efforts in our program is to evaluate the assumptions, limitations, and applicabilities of various analytical models for drift deposition prediction. Several drift deposition models are compared using a set of standard input conditions. The predicted maximum drift deposition differs by two orders of magnitude, and the downwind locations of the maximum differ by one order of magnitude. The discrepancies are attributed mainly to different assumptions in the models regarding the initial effective height of the droplets. Current programs in which drift characteristics at the tower mouth and drift deposition downwind of the tower are being measured are summarized. At the present time, drift deposition measurements, sufficiently comprehensive for model verifications, are unavailable. Hopefully, the Chalk Point Program will satisfy this need

  18. Large area cylindrical silicon drift detector

    International Nuclear Information System (INIS)

    An advanced silicon drift detector, a large area cylindrical drift detector, was designed, produced, tested and installed in the NA45 experiment. The active area of the detector is practically the total area of a 3 inch diameter wafer. Signal electrons created in the silicon detector by fast charged particles drift radially outside toward an array of 360 anodes located on the periphery of the detector. The drift time measures the radial coordinate of the particle's intersection; the charge sharing between anodes measures the azimuthal coordinate. The detector provides unambiguous pairs of r,φ coordinates for events with multiplicities up to several hundred. Its use in the experiment aims at a position resolution of 20 μm (rms) in each direction giving about 2 · 106 two-dimensional elements. There is a small hole in the center of the detector to allow the passage of the noninteracting particle beam. The longest drift distance is about 3 cm. The nominal value of the drift field is 500 V/cm resulting in a maximum drift time of 4 μs

  19. Large area cylindrical silicon drift detector

    International Nuclear Information System (INIS)

    This paper reports on an advanced silicone drift detector, a large area cylindrical drift detector that was designed, produced, tested and installed in the Na45 experiment. The active area of the detector is practically the total area of a 3 inch diameter wafer. Signal electrons created in the silicon detector by fast charged particles drift radially outside toward an array of 360 anodes located on the periphery of the detector. The drift time measures the radial coordinate of the particle's intersection; the charge sharing between anodes measures the azimuthal coordinate. The detector provides unambiguous pairs of r, φ coordinates for events with multiplicities up to several hundred. Its use in the experiment aims at a position resolution of 20 μm (rms) in each direction giving about 2 · 106 two-dimensional elements. There is a small hole in the center of the detector to allow the passage of the noninteracting particle beam. The longest drift distance is about 3 cm. The nominal value of the drift field is 500 V/cm resulting in a maximum drift time of 4 μs

  20. Drift wave turbulence in low-β plasmas

    DEFF Research Database (Denmark)

    Mikkelsen, Torben; Larsen, Søren Ejling; Pécseli, Hans

    1983-01-01

    Experimental investigations of strong turbulence associated with the radial density gradient of a rotating magnetized plasma column are reported. The experiment is designed to make Taylor's hypothesis effective, in order to allow a simple interpretation of measured frequency spectra in terms of...

  1. Drift-Wave Turbulence in Low-β Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1982-01-01

    Experimental investigations of strong turbulence associated with the radial inhomogeneities in a plasma column are reported. The experiment is designed to make Taylor's hypothesis effective. The spectral index of the turbulent potential fluctuations is determined and the variation of the spectral...

  2. Effects of magnetic islands on drift wave instability

    International Nuclear Information System (INIS)

    Magnetic islands have been implemented in the gyrokinetic toroidal code to study the effects of the islands on microturbulence. The pressure profile flattening is verified in the simulation with the islands. Simulations of ion temperature gradient instability find that different toroidal modes are linearly coupled together and that toroidal spectra become broader when the island width increases. The real frequencies and growth rates of different toroidal modes approach each other with the averaged value independent of the island width. The linear mode structures are enhanced at the island separatrices and weakened at the island centers, consistent with the flattening of the pressure profile inside the islands

  3. High Rate Performance of Drift Tubes

    CERN Document Server

    Scherberger, G; Waldmann, V; Landgraf, U; Herten, G; Mohr, W

    1999-01-01

    This article describes calculations and measurements of space charge effects due to high rate irradiation in high resolution drift tubes. Two main items are studied: the reduction of the gas gain and changes of the drift time. Whereas the gain reduction is similar for all gases and unavoidable, the drift time changes depend on the kind of gas that is used. The loss in resolution due to high particle rate can be minimized with a suitable gas. This behaviour is calculable, allowing predictions for new gas mixtures.

  4. High Rate Performance of Drift Tubes

    CERN Document Server

    Scherberger, Guenter; Landgraf, Ulrich; Mohr, Wolfgang; Paschhoff, Volker; Waldmann, Viola

    1998-01-01

    This article describes calculations and measurements of space charge effects due to high rate irradiation in high resolution drift tubes. Two main items are studied: the reduction of the gas gain and changes of the drift time. Whereas the gain reduction is similar for all gases and unavoidable, the drift time changes depend on the kind of gas that is used. The loss in resolution due to high particle rate can be minimized with a suitable gas. This behaviour is calculable, allowing predictions for new gas mixtures.

  5. Wage Drift and Bargaining: Evidence from Norway.

    OpenAIRE

    Holden, Steinar

    1989-01-01

    Empirical equations, based on a theoretical bargaining model, are estimated on data for wage drift in six industries and in the aggregate manufacturing sector in Norway. It is shown that the central wage settlement has a strong impact on aggregate and relative wages in the short run, and that this effect is not offset by wage drift. Wage drift is also found to depend negatively on the size of inventories. This is interpreted as arising from the effect of the initial size of the inventories on...

  6. FIELD INVESTIGATIONS OF THE DRIFT SHADOW

    Energy Technology Data Exchange (ETDEWEB)

    G. W. Su, T. J. Kneafsey, T. A. Ghezzehei, B. D. Marshall, and P. J. Cook

    2006-01-15

    The ''Drift Shadow'' is defined as the relatively drier region that forms below subsurface cavities or drifts in unsaturated rock. Its existence has been predicted through analytical and numerical models of unsaturated flow. However, these theoretical predictions have not been demonstrated empirically to date. In this project they plan to test the drift shadow concept through field investigations and compare our observations to simulations. Based on modeling studies they have an identified suitable site to perform the study at an inactive mine in a sandstone formation. Pretest modeling studies and preliminary characterization of the site are being used to develop the field scale tests.

  7. Coronal Shock Waves, EUV waves, and Their Relation to CMEs. I. Reconciliation of "EIT waves", Type II Radio Bursts, and Leading Edges of CMEs

    OpenAIRE

    Grechnev, V. V.; Uralov, A. M.; Chertok, I. M.; Kuzmenko, I. V.; Afanasyev, A. N.; Meshalkina, N. S.; Kalashnikov, S. S.; Kubo, Y.

    2011-01-01

    We show examples of excitation of coronal waves by flare-related abrupt eruptions of magnetic rope structures. The waves presumably rapidly steepened into shocks and freely propagated afterwards like decelerating blast waves that showed up as Moreton waves and EUV waves. We propose a simple quantitative description for such shock waves to reconcile their observed propagation with drift rates of metric type II bursts and kinematics of leading edges of coronal mass ejections (CMEs). Taking acco...

  8. Scintillator based beta batteries

    Science.gov (United States)

    Rensing, Noa M.; Tiernan, Timothy C.; Shirwadkar, Urmila; O'Dougherty, Patrick; Freed, Sara; Hawrami, Rastgo; Squillante, Michael R.

    2013-05-01

    Some long-term, remote applications do not have access to conventional harvestable energy in the form of solar radiation (or other ambient light), wind, environmental vibration, or wave motion. Radiation Monitoring Devices, Inc. (RMD) is carrying out research to address the most challenging applications that need power for many months or years and which have undependable or no access to environmental energy. Radioisotopes are an attractive candidate for this energy source, as they can offer a very high energy density combined with a long lifetime. Both large scale nuclear power plants and radiothermal generators are based on converting nuclear energy to heat, but do not scale well to small sizes. Furthermore, thermo-mechanical power plants depend on moving parts, and RTG's suffer from low efficiency. To address the need for compact nuclear power devices, RMD is developing a novel beta battery, in which the beta emissions from a radioisotope are converted to visible light in a scintillator and then the visible light is converted to electrical power in a photodiode. By incorporating 90Sr into the scintillator SrI2 and coupling the material to a wavelength-matched solar cell, we will create a scalable, compact power source capable of supplying milliwatts to several watts of power over a period of up to 30 years. We will present the latest results of radiation damage studies and materials processing development efforts, and discuss how these factors interact to set the operating life and energy density of the device.

  9. About some peculiarities of a drift-dissipative instability in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    The local quasiclassical theory of the drift-dissipative instability is in good agreement with the experimental data but it cannot explain some detected peculiarities of the phenomenon, namely the radial wave structure and the absence of the m=1 oscillations. It is shown that these discrepancies can be explained substituting the local quasiclassical approximation theory by a hydrodynamical theory. Solving the differential equations by taking into account the cylindrical walls limiting the plasma, the experimental results can be reproduced. The plasma limits play an important role in the drift-dissipative instability. (D.Gy.)

  10. Resonant interaction of edge dislocations with running acoustic waves

    International Nuclear Information System (INIS)

    The interaction of equilibrium clusters of straight edge dislocations with a monochromatic sound wave having a non-zero wavevector is investigated taking into account the dislocation mass. We report on a significant increase in drift velocities of clusters when the sound wave frequency approaches a cluster's eigenfrequency. Of practical importance is the increase in the drift velocity observed for clusters with a non-zero topological charge interacting with small frequency sound waves

  11. Radially local approximation of drift kinetic equation

    CERN Document Server

    Sugama, H; Satake, S; Kanno, R

    2016-01-01

    A novel radially local approximation of the drift kinetic equation is presented. The new drift kinetic equation that includes both ${\\bf E} \\times {\\bf B}$ and tangential magnetic drift terms is written in the conservative form and it has favorable properties for numerical simulation that any additional terms for particle and energy sources are unnecessary for obtaining stationary solutions under the radially local approximation. These solutions satisfy the intrinsic ambipolarity condition for neoclassical particle fluxes in the presence of quasisymmetry of the magnetic field strength. Also, another radially local drift kinetic equation is presented, from which the positive definiteness of entropy production due to neoclassical transport and Onsager symmetry of neoclassical transport coefficients are derived while it sacrifices the ambipolarity condition for neoclassical particle fluxes in axisymmetric and quasi-symmetric systems.

  12. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    S. Goodin

    1999-07-08

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches.

  13. The Electron Drift Instrument for MMS

    Science.gov (United States)

    Torbert, R. B.; Vaith, H.; Granoff, M.; Widholm, M.; Gaidos, J. A.; Briggs, B. H.; Dors, I. G.; Chutter, M. W.; Macri, J.; Argall, M.; Bodet, D.; Needell, J.; Steller, M. B.; Baumjohann, W.; Nakamura, R.; Plaschke, F.; Ottacher, H.; Hasiba, J.; Hofmann, K.; Kletzing, C. A.; Bounds, S. R.; Dvorsky, R. T.; Sigsbee, K.; Kooi, V.

    2016-03-01

    The Electron Drift Instrument (EDI) on the Magnetospheric Multiscale (MMS) mission measures the in-situ electric and magnetic fields using the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one or more gyrations. This drift is related to the electric field and, to a lesser extent, the gradient in the magnetic field. Although these two quantities can be determined separately by use of different electron energies, for MMS regions of interest the magnetic field gradient contribution is negligible. As a by-product of the drift determination, the magnetic field strength and constraints on its direction are also determined. The present paper describes the scientific objectives, the experimental method, and the technical realization of the various elements of the instrument on MMS.

  14. CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

    International Nuclear Information System (INIS)

    The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches

  15. Self-shielding flex-circuit drift tube, drift tube assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Jones, David Alexander

    2016-04-26

    The present disclosure is directed to an ion mobility drift tube fabricated using flex-circuit technology in which every other drift electrode is on a different layer of the flex-circuit and each drift electrode partially overlaps the adjacent electrodes on the other layer. This results in a self-shielding effect where the drift electrodes themselves shield the interior of the drift tube from unwanted electro-magnetic noise. In addition, this drift tube can be manufactured with an integral flex-heater for temperature control. This design will significantly improve the noise immunity, size, weight, and power requirements of hand-held ion mobility systems such as those used for explosive detection.

  16. On the electron drift velocity in plasma devices with E × B drift

    Science.gov (United States)

    Chapurin, O.; Smolyakov, A.

    2016-06-01

    The structure and various components of the electron drift velocity are discussed in application to plasma discharges with the E × B drift. In high density plasmas, the contribution of the diamagnetic drift can be of the same order magnitude as the E × B drift. It is pointed out that curvature and gradient drifts associated with magnetic field inhomogeneities manifest themselves via the electron pressure anisotropy. Estimates show that the components of the diamagnetic drift related to the electron pressure anisotropy and magnetic field gradients can be important for the parameters of modern magnetrons and Hall thrusters. Similar additional terms appear in the momentum balance as mirror forces which may affect the distribution of the electrostatic potential in Hall devices.

  17. SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

    Energy Technology Data Exchange (ETDEWEB)

    C. Tsang

    2004-09-22

    The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, the van Genuchten 1/a parameter, and percolation flux) and drift degradation shape scenarios in support of the TSPA-LA during the period of compliance for postclosure performance [Technical Work Plan for: Performance Assessment Unsaturated Zone (BSC 2002 [DIRS 160819], Section I-4-2-1)]. The flow-focusing model in the Topopah Spring welded (TSw) unit is intended to provide an estimate of flow focusing factors (FFFs) that (1) bridge the gap between the mountain-scale and drift-scale models, and (2) account for variability in local percolation flux due to

  18. The Bipolar Quantum Drift-diffusion Model

    Institute of Scientific and Technical Information of China (English)

    Xiu Qing CHEN; Li CHEN

    2009-01-01

    A fourth order parabolic system, the bipolar quantum drift-diffusion model in semiconductor simulation, with physically motivated Dirichlet-Neumann boundary condition is studied in this paper. By semidiscretization in time and compactness argument, the global existence and semiclassical limit are obtained, in which semiclassical limit describes the relation between quantum and classical drift-diffusion models. Furthermore, in the case of constant doping, we prove the weak solution exponentially approaches its constant steady state as time increases to infinity.

  19. Effects of Fault Displacement on Emplacement Drifts

    International Nuclear Information System (INIS)

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10-5 adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M and O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure

  20. Beam test results of a drift velocity monitoring system for silicon drift detectors

    CERN Document Server

    Nouais, D; Bonvicini, V; Cerello, P; Giubellino, P; Hernández-Montoya, R; Kolojvari, A; Mazza, G; Nissinen, J; Rashevsky, A; Rivetti, A; Tosello, F; Vacchi, A

    2002-01-01

    We report results on drift velocity monitoring using MOS charge injectors in silicon drift detectors obtained in beam test conditions. The correction of velocity variations as small as 0.03% caused by temperature variations of the order of 0.04 K allowed to get an average space resolution along all the drift path of 28 mu m. Preliminary result demonstrating the possibility to correct for temperature gradients along the anode axis are also presented.

  1. BETA-S, Multi-Group Beta-Ray Spectra

    International Nuclear Information System (INIS)

    1 - Description of program or function: BETA-S calculates beta-decay source terms and energy spectra in multigroup format for time-dependent radionuclide inventories of actinides, fission products, and activation products. Multigroup spectra may be calculated in any arbitrary energy-group structure. The code also calculates the total beta energy release rate from the sum of the average beta-ray energies as determined from the spectral distributions. BETA-S also provides users with an option to determine principal beta-decaying radionuclides contributing to each energy group. The CCC-545/SCALE 4.3 (or SCALE4.2) code system must be installed on the computer before installing BETA-S, which requires the SCALE subroutine library and nuclide-inventory generation from the ORIGEN-S code. 2 - Methods:Well-established models for beta-energy distributions are used to explicitly represent allowed, and 1., 2. - and 3. -forbidden transition types. Forbidden non-unique transitions are assumed to have a spectral shape of allowed transitions. The multigroup energy spectra are calculated by numerically integrating the energy distribution functions using an adaptive Simpson's Rule algorithm. Nuclide inventories are obtained from a binary interface produced by the ORIGEN-S code. BETA-S calculates the spectra for all isotopes on the binary interface that have associated beta-decay transition data in the ENSDF-95 library, developed for the BETA-S code. This library was generated from ENSDF data and contains 715 materials, representing approximately 8500 individual beta transition branches. 3 - Restrictions on the complexity of the problem: The algorithms do not treat positron decay transitions or internal conversion electrons. The neglect of positron transitions in inconsequential for most applications involving aggregate fission products, since most of the decay modes are via electrons. The neglect of internal conversion electrons may impact on the accuracy of the spectrum in the low

  2. Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

    CERN Document Server

    Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; 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Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; Swain, J; Taylor, L; Tuura, L; Anastassov, A; Gobbi, B; Kubik, A; Ofierzynski, R A; Pozdnyakov, A; Schmitt, M; Stoynev, S; Velasco, M; Won, S; Antonelli, L; Berry, D; Hildreth, M; Jessop, C; Karmgard, D J; Kolberg, T; Lannon, K; Lynch, S; Marinelli, N; Morse, D M; Ruchti, R; Slaunwhite, J; Warchol, J; Wayne, M; Bylsma, B; Durkin, L S; Gilmore, J; Gu, J; Killewald, P; Ling, T Y; Williams, G; Adam, N; Berry, E; Elmer, P; Garmash, A; Gerbaudo, D; Halyo, V; Hunt, A; Jones, J; Laird, E; Marlow, D; Medvedeva, T; Mooney, M; Olsen, J; Piroué, P; Stickland, D; Tully, C; Werner, J S; Wildish, T; Xie, Z; Zuranski, A; Acosta, J G; Bonnett Del Alamo, M; Huang, X T; Lopez, A; Mendez, H; Oliveros, S; Ramirez Vargas, J E; Santacruz, N; Zatzerklyany, A; Alagoz, E; Antillon, E; Barnes, V E; Bolla, G; Bortoletto, D; Everett, A; Garfinkel, A F; Gecse, Z; Gutay, L; Ippolito, N; Jones, M; Koybasi, O; Laasanen, A T; Leonardo, N; Liu, C; Maroussov, V; Merkel, P; Miller, D H; Neumeister, N; Sedov, A; Shipsey, I; Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

    2010-01-01

    This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

  3. Synergistic effects of magnetic and velocity shear on electromagnetic drift modes in tokamaks

    International Nuclear Information System (INIS)

    Full text: In the fluid model, electromagnetic drift mode in low beta tokamak plasmas is studied from a set of new-derived eigenequations, including magnetic shear, perpendicular and parallel velocity shears, perpendicular and parallel current density and their shears, and finite beta. It is found that there exists a threshold of perpendicular velocity shear, at which the growth rate tends to zero. The threshold increases with decrease of magnetic shear. On the other hand, the increase of beta reduces the growth rate but increases the velocity shear threshold. In addition, we study the effects of parallel velocity shear on the instability and find that it enhances the instability. Furthermore, the preliminary calculations show that the perpendicular current density shear suppresses the instability while the parallel current density shear strengthens it. (author)

  4. Theoretical and experimental investigation of the drift velocity in AlGaAs/GaAs heterostructures

    Science.gov (United States)

    Zandler, G.; Kiener, C.; Boxleitner, W.; Vass, E.; Wirner, C.; Gornik, E.; Weimann, G.

    1991-12-01

    The drift velocity of hot electrons in AlGaAs/GaAs heterostructures is measured at different temperatures by a pulsed I-V technique up to electric fields of 1.2 kV/cm. The experimental results are compared with theoretical drift velocities deduced from the Boltzmann integral equation and a balance equation method. The calculations are carried out with selfconsistent and Stern-Howard wave functions taking into account polar optical phonon and ionized impurity scattering as well as electron-electron collisions. At low field strengths both theoretical methods lead to drift velocities which are in good agreement with the experimental data. It is shown that for higher lattice temperatures and higher electric field strengths intersubband scattering has to be taken into account in the theoretical models.

  5. Growth and stabilization of drift-tearing modes in weakly collisional plasmas

    Science.gov (United States)

    Grasso\\ad{a}, D.; Ottaviani, M.; Porcelli\\ad{a}, F.

    2002-09-01

    In the limit where the electron drift-wave frequency exceeds the electron-ion collision frequency, drift-tearing modes are found to grow with a linear growth rate independent of resistivity and proportional to the product of the electron inertial skin depth and the ion sound Larmor radius. The stabilization of these modes in collisionless and semi-collisional regimes is investigated. The stabilization mechanism is related to the coupling and propagation of drift-acoustic perturbations away from the reconnecting mode-rational surface. Analytic and numerical solutions of the four-field reduced fluid model in the slab geometry approximation with constant electron temperature and negligible ion temperature are presented. The actual stability threshold can occur at values of the normalized tearing mode stability parameter Δ' as high as 102.\\pacs{52.35.P}} \\fnm{1}{Permanent address: Istituto Nazionale Fisica della Materia, Department of Energetics, Politecnico di Torino, Italy

  6. Synchrotron emission driven by the Cherenkov-drift instability in active galactic nuclei

    CERN Document Server

    Osmanov, Zaza

    2012-01-01

    In the present paper we study generation of the synchrotron emission by means of the feedback of Cherenkov drift waves on the particle distribution via the diffusion process. It is shown that despite the efficient synchrotron losses the excited Cherenkov drift instability leads to the quasi-linear diffusion (QLD), effect of which is balanced by dissipation factors and as a result the pitch angles are prevented from damping, maintaining the corresponding synchrotron emission. The model is analyzed for a wide range of physical parameters and it is shown that the mechanism of QLD guarantees the generation of electromagnetic radiation from soft $X$-rays up to soft $\\gamma$-rays, strongly correlated with Cherenkov drift emission ranging from IR up to UV energy domains.

  7. Design and development of cold prototypes of post coupled Alvarez type Drift Tube Linac for LEHIPA

    International Nuclear Information System (INIS)

    Alvarez type Drift Tube Linac (DTL) is used for acceleration of proton beaming low energy section of beta ranging from 0.04 to 0.40. DTL form part of LEHIPA (Low Energy High Intensity Proton Accelerator) for acceleration of protons from 3 MeV to 20 MeV energy. DTL is cylindrical RF cavity resonating in TM010 mode at 352.21 MHz frequency. It consists of array of drift tubes arranged ensuring that DTL centre and Drift Tube centre are concentric. The Drift Tubes also houses Permanent Magnet Quadrupole for transverse focusing of proton beam. A twelve cell cold prototype of DTL section is designed, developed and fabricated at Bhabha Atomic Research Centre, Trombay. Complete DTL accelerator consists of eight such DTL sections. High frequency microwave simulations are carried out in SOPRANO, vector fields and COMSOL simulation software. This prototype DTL is 1640.56 mm long cavity with 520 mm ID, 600 mm OD and consists of eleven Drift Tubes, two RF end flanges, three slug tuners, six post couplers, three RF field monitors, one RF waveguide coupler, two DN100 vacuum flanges and DTL tank platform with alignment features. Girder based Drift tube mounting arrangement utilizing uncompressing energy of disc springs for optimum combo RF-vacuum seal compression is worked out and implemented. This paper discusses design of this vacuum cavity and discusses results on mechanical accuracy achieved on scaled pre-prototype, and comments on low level RF measurements and vacuum integrity on the cold DTL prototype. (author)

  8. Beta Gyres in Global Analysis Fields

    Institute of Scientific and Technical Information of China (English)

    Sun-Hee KIM; H.Joe KWON; R.L.ELSBERRY

    2009-01-01

    A three-component decomposition is applied to global analysis data to show the existence of a beta gyre,which causes Tropical Cyclone (TC) to drift from a large-scale environmental steering current.Analyses from the Global Data Assimilation and Prediction System (GDAPS) of the Korea Meteorological Administration (KMA),the Global Forecast System (GFS) of NCEP,and the Navy Operational Global Atmospheric Prediction System (NOGAPS) are used in this study.The structure of the beta gyre obtained in our analyses is in good agreement with the theoretical structure,with a cyclonic circulation to the southwest of the TC center,an anticyclonic circulation to the northeast,and a ventilation flow directed northwestward near the center.The circulation of the beta gyre is strongest at the 850-hPa level where the cyclonically swirling primary circulation is strongest,and decreases with height,in a pyramid shape similar to the primary circulation.The individual structure of the beta gyre is case- and model-dependent.At a certain analysis time,one model may clearly reveal a well-defined beta gyre,but the other models may not.Within one model,the beta gyre may be well defined at some analysis times,but not at other times.The structure of the beta gyre in the analysis field is determined by the nature of the vortex initialization scheme and the model behavior during the 6-h forecast in the operational data assimilation cycle.

  9. Performance of the SLD Central Drift Chamber

    International Nuclear Information System (INIS)

    We report for the first time on the performance of the SLD Central Drift Chamber (CDC) at SLC, which has been recording data since 1992. The low mass of the chamber and the use of a gas characterized by both a low drift velocity and low diffusion constant help to minimize the drift-distance measurement errors. We describe some of the calibrations and corrections applied to the data, and report on the resolutions achieved thus far. We measure an intrinsic drift resolution of 55-110 μm in the region of uniform field. Analysis of the full drift-pulse waveform allows for efficient double-hit resolution of about 1 mm. Momentum resolution is characterized by the formula (dpt/pt2)2 = 0.00502 + (0.010/pt)2. Used in conjunction with the SLD vertex detector, the CDC permits measurements of impact parameters of high-momentum tracks to the level of 10 μm in the r-φ plane and 36 μm the r-z plane. A resolution of 6.4% is achieved in the measurement of dE/dx for the electrons in Bhabha scattering events

  10. Drift emplaced waste package thermal response

    International Nuclear Information System (INIS)

    Thermal calculations of the effects of radioactive waste decay heat on the potential repository at Yucca Mountain, Nevada, have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore National Lab. (LLNL) in conjunction with the B ampersand W Fuel Co. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic temperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not a strong driver on rock temperature; AML has a larger impact. High AMLs occur when large waste packages are emplaced end-to-end in drifts. Drift emplacement of equivalent packages results in lower rock temperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML of 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160 degrees C, but rock temperatures exceed the boiling point of water for about 3000 years. These TOPAZ3D results have been compared with reasonable agreement with two other computer codes

  11. Gravitational radiation from neutron stars deformed by crustal Hall drift

    CERN Document Server

    Suvorov, Arthur George; Geppert, Ulrich

    2016-01-01

    A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within $\\sim 10^4$ -- $10^5$ yr, magnetic spots with local surface field strengths $\\sim 10^{14}$ G maintained over $\\gtrsim 10^6$ yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity $\\epsilon\\sim 10^{-6}$, even with sub-magnetar polar field strengths, after $\\sim 10^5$ ...

  12. Electron drift velocities in fast Argon and CF4 based drift gases

    CERN Document Server

    van Apeldoorn, G

    1998-01-01

    98-063 Electron drift velocities in gas mixtures were measured in a tabletop experiment using a nitrogen laser to create the primary electrons. The maximum drift times for electrons in a 5 mm (10 mm) honeycomb drift cell at 2200 V anode voltage were 28 ns (53 ns) and 21 ns (61 ns) for Ar-Cf4-CH4 (75/18/6) and Ar-CF4-CO2 (68/27/5), respectively. Changing the ratio of the latter mix did not change the drift velocity very much. The gains of the gases are ~10^4 for a single primary electron. CF4 causes electron attachment. The measured drift times agree well with GARFIELD simulations.

  13. Final Report for DUSEL R&D: BetaCage: A Screener of Ultra-Low-Level Radioactive Surface Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Golwala, Sunil R. [California Institute of Technology

    2013-12-20

    The eventual full-size, radiopure BetaCage will be a low-background, atmospheric-pressure neon drift chamber with unprecedented sensitivity to emitters of low-energy electrons and alpha particles. We expect that the prototype BetaCage already developed will be an excellent screener of alpha particles. Both the prototype and final BetaCage will provide new infrastructure for rare-event science.

  14. Renormalized turbulence theory of ion pressure gradient driven drift modes

    International Nuclear Information System (INIS)

    From the nonlinear gyrokinetic equation we formulate the renormalized turbulence equation for the eta/sub i/-mode drift wave instability. The study shows that the dominant nonlinear damping mechanism is from the E x B convection of the pressure fluctuation and that the kinetic modifications to the fluid E x B mode coupling, studied earlier, shift the spectrum toward the shorter wavelengths. Balancing the linear growth rate with the nonlinear dampling rate at the linearly most unstable region, we calculate the anomalous ion thermal conductivity which exceeds the neoclassical plateau formula and gives a value of the same order as that previously computed by Horton, Choi and Tank, but with a kinetic enhancement factor. Also, the thermal conductivity formula remains finite for vanishing density gradient. 23 refs

  15. The KLOE drift chamber VCI 2001

    Energy Technology Data Exchange (ETDEWEB)

    Adinolfi, M.; Aloisio, A.; Ambrosino, F.; Andryakov, A.; Antonelli, A.; Antonelli, M.; Anulli, F.; Bacci, C.; Bankamp, A.; Barbiellini, G.; Bellini, F.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Cabibbo, G.; Calcaterra, A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Cardini, A.; Casarsa, M.; Cataldi, G.; Ceradini, F.; Cervell, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; Conticelli, S.; De Lucia, E. E-mail: erika.delucia@roma1.infn.it; De Robertis, G.; De Sangro, R.; De Simone, P.; De Zorzi, G.; Dell' Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Doria, A.; Drago, E.; Elia, V.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gao, M.L.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Golovatyuk, V.; Gorini, E.; Grancagnolo, F.; Grandegger, W.; Graziani, E.; Guarnaccia, P.; Hagel, U. von.; Han, H.G.; Han, S.W.; Huang, X.; Incagli, M.; Ingrosso, L.; Jang, Y.Y.; Kim, W.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Lomtadze, F.; Luisi, C.; Mao, C.S.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moalem, A.; Moccia, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Panareo, M.; Pacciani, L.; Pages, P.; Palutan, M.; Paoluzi, L.; Pasqualucci, E.; Passalacqua, L.; Passaseo, M.; Passeri, A.; Patera, V.; Petrolo, E.; Petrucci, G.; Picca, D.; Pirozzi, G.; Pistillo, C.; Pollack, M.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Schwick, C.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Shan, J.; Silano, P.; Spadaro, T.; Spagnolo, S.; Spiriti, E.; Stanescu, C.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Venanzoni, G.; Veneziano, S.; Wu, Y.; Xie, Y.G.; Zhao, P.P.; Zhou, Y

    2002-02-01

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum K{sub L} ({lambda}{sub L}=3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged K{sub L} decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed.

  16. The KLOE drift chamber VCI 2001

    International Nuclear Information System (INIS)

    The main goal of the KLOE experiment at the Frascati DAPHINE phi-factory is the study CP violation in kaon decays. The tracking device of the experiment is a drift chamber whose dimensions, 4 m of diameter and 3.3 m length, provide a large acceptance volume for the decay products of low momentum KL (λL=3.4 m). A complete stereo geometry with 12.582 cells arranged in 58 layers guarantees a high and uniform efficiency in the reconstruction of the charged KL decays. Very light materials have been chosen both for the drift medium, a helium-based gas mixture, and for the mechanical structure, made of carbon fiber, to minimize multiple scattering and conversion of low-energy photons. The design requirements, the adopted solutions together with the calibration procedure and the tracking performances of the drift chamber are discussed

  17. Drift chamber tracking with neural networks

    International Nuclear Information System (INIS)

    With the very high event rates projected for experiments at the SSC and LHC, it is important to investigate new approaches to on line pattern recognition. The use of neural networks for pattern recognition. The use of neural networks for pattern recognition in high energy physics detectors has been an area of very active research. The authors discuss drift chamber tracking with a commercial analog VLSI neural network chip. Voltages proportional to the drift times in a 4-layer drift chamber were presented to the Intel ETANN chip. The network was trained to provide the intercept and slope of straight tracks traversing the chamber. The outputs were recorded and later compared off line to conventional track fits. Two types of network architectures were studied. Applications of neural network tracking to high energy physics detector triggers is discussed

  18. Detection relic gravitational waves in thermal case

    CERN Document Server

    Ghayour, Basem

    2016-01-01

    The thermal spectrum of relic gravitational waves causes the new amplitude that called `modified amplitude'. Our analysis shows that, there exist some chances for detection of the thermal spectrum in addition to the usual spectrum by Adv.LIGO and Dml detectors. The behaviour of the inflation and reheating stages are often known as power law expansion like $S(\\eta)\\propto \\eta^{1+\\beta}$, $S(\\eta)\\propto \\eta^{1+\\beta_s}$ respectively. The $\\beta$ and $\\beta_s$ have an unique effect on the shape of the spectrum. We find some upper bounds on the $\\beta$ and $\\beta_s$ by comparison the usual and thermal spectrum with the Adv.LIGO and Dml. As this result gives us more information about the nature of the evolution of inflation and reheating stages.

  19. Drifts of Dust or Something Else?

    Science.gov (United States)

    2004-01-01

    While the interior and far walls of the crater dubbed 'Bonneville' can be seen in the background, the dominant foreground features in this 180-degree navigation camera mosaic are the wind-deposited drifts of dust or sand. NASA's Mars Exploration Rover Spirit completed this mosaic on sol 71, March 15, 2004, from its newest location at the rim of 'Bonneville' crater. Scientists are interested in these formations in part because they might give insight into the processes that formed some of the material within the crater. Thermal emission measurements by the rover indicate that the dark material just below the far rim of this crater is spectrally similar to rocks that scientists have analyzed along their journey to this location. They want to know why this soil-like material has a spectrum that more closely resembles rocks rather than other soils examined so far. The drifts seen in the foreground of this mosaic might have the answer. Scientists hypothesize that these drifts might consist of wind-deposited particles that are the same as the dark material found against the back wall of the crater. If so, Spirit may spend time studying the material and help scientists understand why it is different from other fine-grained material seen at Gusev. The drifts appear to be lighter in color than the dark material deposited on the back wall of the crater. They might be covered by a thin deposit of martian dust, or perhaps the drift is like other drifts seen during Spirit's journey and is just a collection of martian dust. To find out, Spirit will spend some of sol 72 digging its wheels into the drift to uncover its interior. After backing up a bit, Spirit will use the panoramic camera and miniature thermal emission spectrometer to analyze the scuffed area. If the interior material has a similar spectrum to the dark deposit in the crater, then Spirit will most likely stay here a little longer to study the drift with the instruments on its robotic arm. If the material is uniform

  20. Silicon Drift Detectors development for position sensing

    International Nuclear Information System (INIS)

    Novel Silicon Drift Detectors (SDDs) with multi-linear architecture specifically intended for 2D position sensing and imaging applications are presented and their achievable spatial, energy and time resolution are discussed. The capability of providing a fast timing of the interaction with nanosecond time resolution is a new available feature that allows operating the drift detector in continuous readout mode for coincidence imaging applications either with an external trigger or in self-timing. The application of SDDs with multi-linear architecture to Compton electrons' tracking within a single silicon layer and the achieved experimental results will be discussed

  1. Realtime vision-based lateral drift correction

    OpenAIRE

    Hübner, T; Pajarola, R.

    2009-01-01

    A major drawback in many robotics projects is the dependance on a specific environment and the otherwise uncertain behavior of the hardware. Simple navigation tasks like driving in a straight line can lead to a strong lateral drift over time in an unknown environment. In this paper we propose a fast and simple solution for the lateral drift problem for vision guided robots by real-time scene analysis. Without an environment-specific calibration of the robot’s drive system, we balance the ...

  2. Price Drift on the Stockholm Stock Exchange

    OpenAIRE

    Höijer, Mattias; Lejdelin, Martin; Lindén, Patrik

    2007-01-01

    This paper examines whether the phenomena of price drift around quarterly earnings re-leases exist among firms listed on the large cap. list at the Stockholm Stock Exchange for a time period ranging from the first quarter of 2003 to the second quarter of 2006. It fur-thermore examines the ability of the variables forecast error, relative to analyst’s estimates, and firms’ size to explain the variation in price drift among firms. A sample of some 30 firms were drawn in the first three quarters...

  3. Continental drift, organic evolution, and moral courage

    Science.gov (United States)

    Irving, Edward

    For the past 40 years or so there has been much discussion of the reasons why, even though there was substantial evidence for it, the continental drift hypothesis of Alfred Wegener and Wladimir Koppen was rejected in the first half of the 20th century. It was often derisively dismissed out of hand.On April 7, 1998, there was a note in Eos by David Stern that included a perceptive and amusing quotation from Teddy Bullard on the question, which has recently reached something of a culmination in an important new book, The Rejection of Continental Drift, by Naomi Oreskes and published by Oxford in 1999.

  4. Particle acceleration in tangential discontinuities by lower hybrid waves

    Directory of Open Access Journals (Sweden)

    D. Spicer

    2002-01-01

    Full Text Available We consider the role that the lower-hybrid wave turbulence plays in providing the necessary resistivity at collisionless reconnection sights. The mechanism for generating the waves is considered to be the lower-hybrid drift instability. We find that the level of the wave amplitude is sufficient enough to heat and accelerate both electrons and ions.

  5. Stability analysis of abandoned drift for alternative utilization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo-Hyun; Yoo, In-Kol; Kim, Moon-Seob; Kim, Ryang-Hee [Korea Resources Corp., Seoul(Korea); Yang, Hyung-Sik [Chonnam National University, Kwangju(Korea); Lee, Hi-Keun [Seoul National University, Seoul(Korea); Kim, Jae-Dong [Kangwon National University, Chuncheon(Korea)

    2000-04-30

    This study was performed to find the way that is alternative utilization of the drift that had been abandoned by coal industry promotion. To determine whether abandoned drift would be maintained without supports or not, the safety inspection that consists of drift survey, laboratory tests, rock mass classification and numerical analysis was performed. According to the result, there were discontinuity sets those had unfavorable orientation to the drift and rock mass around the drift had generally poor condition. So, it would be much difficult that abandoned drift is maintained without supports. (author). 15 refs., 8 tabs., 7 figs.

  6. Asymptotic dynamics of reflecting spiral waves

    OpenAIRE

    Langham, Jacob; Biktasheva, Irina; Barkley, Dwight

    2014-01-01

    Resonantly forced spiral waves in excitable media drift in straight-line paths, their rotation centers behaving as point-like objects moving along trajectories with a constant velocity. Interaction with medium boundaries alters this velocity and may often result in a reflection of the drift trajectory. Such reflections have diverse characteristics and are known to be highly nonspecular in general. In this context we apply the theory of response functions, which via numerically computable inte...

  7. Formation mechanism of steep wave front in magnetized plasmas

    International Nuclear Information System (INIS)

    Bifurcation from a streamer to a solitary drift wave is obtained in three dimensional simulation of resistive drift waves in cylindrical plasmas. The solitary drift wave is observed in the regime where the collisional transport is important as well as fluctuation induced transport. The solitary drift wave forms a steep wave front in the azimuthal direction. The phase of higher harmonic modes are locked to that of the fundamental mode, so that the steep wave front is sustained for a long time compared to the typical time scale of the drift wave oscillation. The phase entrainment between the fundamental and second harmonic modes is studied, and the azimuthal structure of the stationary solution is found to be characterized by a parameter which is determined by the deviation of the fluctuations from the Boltzmann relation. There are two solutions of the azimuthal structures, which have steep wave front facing forward and backward in the wave propagation direction, respectively. The selection criterion of these solutions is derived theoretically from the stability of the phase entrainment. The simulation result and experimental observations are found to be consistent with the theoretical prediction

  8. Plate Tectonics and Continental Drift: Classroom Ideas.

    Science.gov (United States)

    Stout, Prentice K.

    1983-01-01

    Suggests various classroom studies related to plate tectonics and continental drift, including comments on and sources of resource materials useful in teaching the topics. A complete list of magazine articles on the topics from the Sawyer Marine Resource Collection may be obtained by contacting the author. (JN)

  9. The Drift Chambers Of The Nomad Experiment

    CERN Document Server

    Anfreville, M G; Authier, M; Baldisseri, Alberto; Banner, M; Besson, N; Bouchez, J; Castera, A; Cloué, O; Dumarchez, J; Dumps, Ludwig; Gangler, E; Gosset, J; Hagner, C; Jollec, C; Lachaud, C; Letessier-Selvon, A A; Lévy, J M; Linssen, Lucie; Meyer, J P; Ouriet, J P; Passerieux, J P; Pédrol, T; Placci, Alfredo; Poinsignon, J; Popov, B; Rathouit, P; Schahmaneche, K; Stolarczyk, T; Urós, V; Vannucci, François; Vo, M K; Zaccone, Henri

    2002-01-01

    We present a detailed description of the drift chambers used as an active target and a tracking device in the NOMAD experiment at CERN. The main characteristics of these chambers are a large area, a self supporting structure made of light composite materials and a low cost. A spatial resolution of 150 microns has been achieved with a single hit efficiency of 97%.

  10. Multidimensional stochastic differential equations with distributional drift

    OpenAIRE

    Flandoli, Franco; Issoglio, Elena; Russo, Francesco

    2015-01-01

    This paper investigates a time-dependent multidimensional stochastic differential equation with drift being a distribution in a suitable class of Sobolev spaces with negative derivation order. This is done through a careful analysis of the corresponding Kolmogorov equation whose coefficient is a distribution.

  11. Effects of Drifting Macroalgae in Eelgrass Ecosystems

    DEFF Research Database (Denmark)

    Canal Vergés, Paula; Valdemarsen, Thomas Bruun; Kristensen, Erik;

    2010-01-01

    physical damage on eelgrass can occur when macroalgae are drifting as bedload. The ballistic effect of moving macroalgae on surface sediment was tested in the field as well as in a series of annular flume experiments, where simultaneous measurements of macroalgae transport and turbidity were measured at...

  12. On diffusion, drift and the Einstein relation

    International Nuclear Information System (INIS)

    The diffusivity, mobility and limitations of the Einstein relation are discussed by means of two pedagogical examples. In a simple one-dimensional analysis, we compute the consequences of the single-particle occupancy restriction and correlations over two successive steps on the diffusion and drift fluxes and on the particle distribution functions. (author)

  13. Stable discrete representation of relativistically drifting plasmas

    CERN Document Server

    Kirchen, Manuel; Godfrey, Brendan B; Dornmair, Irene; Jalas, Soeren; Peters, Kevin; Vay, Jean-Luc; Maier, Andreas R

    2016-01-01

    Representing the electrodynamics of relativistically drifting particle ensembles in discrete, co-propagating Galilean coordinates enables the derivation of a Particle-in-Cell algorithm that is intrinsically free of the Numerical Cherenkov Instability, for plasmas flowing at a uniform velocity. Application of the method is shown by modeling plasma accelerators in a Lorentz-transformed optimal frame of reference.

  14. Levered and unlevered Beta

    OpenAIRE

    Fernandez, Pablo

    2003-01-01

    We prove that in a world without leverage cost the relationship between the levered beta ( L) and the unlevered beta ( u) is the No-costs-of-leverage formula: L = u + ( u - d) D (1 - T) / E. We also analyze 6 alternative valuation theories proposed in the literature to estimate the relationship between the levered beta and the unlevered beta (Harris and Pringle (1985), Modigliani and Miller (1963), Damodaran (1994), Myers (1974), Miles and Ezzell (1980), and practitioners) and prove that all ...

  15. Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model

    Science.gov (United States)

    Tao, Xie; William, Perrie; Shang-Zhuo, Zhao; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-07-01

    Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service Program.

  16. Betting Against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    .S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return of the...

  17. Forward-Looking Betas

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory

    Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward-...

  18. Shear Alfven waves in tokamaks

    International Nuclear Information System (INIS)

    Shear Alfven waves in an axisymmetric tokamak are examined within the framework of the linearized ideal MHD equations. Properties of the shear Alfven continuous spectrum are studied both analytically and numerically. Implications of these results in regards to low frequency rf heating of toroidally confined plasmas are discussed. The structure of the spatial singularities associated with these waves is determined. A reduced set of ideal MHD equations is derived to describe these waves in a very low beta plasma

  19. The Effects of Clock Drift on the Mars Exploration Rovers

    Science.gov (United States)

    Ali, Khaled S.; Vanelli, C. Anthony

    2012-01-01

    All clocks drift by some amount, and the mission clock on the Mars Exploration Rovers (MER) is no exception. The mission clock on both MER rovers drifted significantly since the rovers were launched, and it is still drifting on the Opportunity rover. The drift rate is temperature dependent. Clock drift causes problems for onboard behaviors and spacecraft operations, such as attitude estimation, driving, operation of the robotic arm, pointing for imaging, power analysis, and telecom analysis. The MER operations team has techniques to deal with some of these problems. There are a few techniques for reducing and eliminating the clock drift, but each has drawbacks. This paper presents an explanation of what is meant by clock drift on the rovers, its relationship to temperature, how we measure it, what problems it causes, how we deal with those problems, and techniques for reducing the drift.

  20. Barber's Point, Oahu, Hawaii Drift Card Study 2002-2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Drift cards were be released from Barber's Point, Oahu, approximately once a month during the two year span to get an idea of the distribution of card drift under...

  1. Strategies for Dealing with Drift during Implementation of ERP Systems

    NARCIS (Netherlands)

    P.J. van Baalen (Peter); P.C. van Fenema (Paul)

    2005-01-01

    textabstractResearch on the relationship between Information Technology (IT) and organizations emphasizes the complexity of adaptation processes and the potential of drifting. Drifting means that an organization encounters unexpected circumstances that show the incompleteness and possible failure of

  2. Drift-Scale THC Seepage Model

    International Nuclear Information System (INIS)

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC submodel uses a drift

  3. Drift-Scale THC Seepage Model

    Energy Technology Data Exchange (ETDEWEB)

    C.R. Bryan

    2005-02-17

    The purpose of this report (REV04) is to document the thermal-hydrologic-chemical (THC) seepage model, which simulates the composition of waters that could potentially seep into emplacement drifts, and the composition of the gas phase. The THC seepage model is processed and abstracted for use in the total system performance assessment (TSPA) for the license application (LA). This report has been developed in accordance with ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Post-Processing Analysis for THC Seepage) Report Integration'' (BSC 2005 [DIRS 172761]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this report. The plan for validation of the models documented in this report is given in Section 2.2.2, ''Model Validation for the DS THC Seepage Model,'' of the TWP. The TWP (Section 3.2.2) identifies Acceptance Criteria 1 to 4 for ''Quantity and Chemistry of Water Contacting Engineered Barriers and Waste Forms'' (NRC 2003 [DIRS 163274]) as being applicable to this report; however, in variance to the TWP, Acceptance Criterion 5 has also been determined to be applicable, and is addressed, along with the other Acceptance Criteria, in Section 4.2 of this report. Also, three FEPS not listed in the TWP (2.2.10.01.0A, 2.2.10.06.0A, and 2.2.11.02.0A) are partially addressed in this report, and have been added to the list of excluded FEPS in Table 6.1-2. This report has been developed in accordance with LP-SIII.10Q-BSC, ''Models''. This report documents the THC seepage model and a derivative used for validation, the Drift Scale Test (DST) THC submodel. The THC seepage model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral

  4. Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave–current coupled model

    Science.gov (United States)

    Tao, Xie; Shang-Zhuo, Zhao; William, Perrie; He, Fang; Wen-Jin, Yu; Yi-Jun, He

    2016-06-01

    To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave–current model is derived, based on the mechanism of wave–current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave–current interaction effect of the ocean current is much stronger than that of the nonlinear wave–wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal. Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program on Energy Research and Development, and the Canadian World Class Tanker Safety Service.

  5. Seasonal and longitudinal dependence of equatorialdisturbance vertical plasma drifts

    OpenAIRE

    Fejer, Bela G.; Jensen, J. W.; Su, S.Y.

    2008-01-01

    [1] We used equatorial measurements from the ROCSAT-1 satellite to determine the seasonal and longitudinal dependent equatorial F region disturbance vertical plasma drifts. Following sudden increases in geomagnetic activity, the prompt penetration vertical drifts are upward during the day and downward at night, and have strong local time dependence at all seasons. The largest prompt penetration drifts near dusk and dawn occur during June solstice. The daytime disturbance dynamo drifts are sma...

  6. Electromagnetic drift modes in an inhomogeneous electron gas

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices......A pair of nonlinear equations is derived which describes the dynamics of the electromagnetic drift oscillations in a nonuniform magnetized electron gas. It is shown that the nonlinear electromagnetic drift modes can propagate in the form of dipole vortices...

  7. Self-Attractive Random Walks: The Case of Critical Drifts

    Science.gov (United States)

    Ioffe, Dmitry; Velenik, Yvan

    2012-07-01

    Self-attractive random walks (polymers) undergo a phase transition in terms of the applied drift (force): If the drift is strong enough, then the walk is ballistic, whereas in the case of small drifts self-attraction wins and the walk is sub-ballistic. We show that, in any dimension d ≥ 2, this transition is of first order. In fact, we prove that the walk is already ballistic at critical drifts, and establish the corresponding LLN and CLT.

  8. Self-Attractive Random Walks: The Case of Critical Drifts

    CERN Document Server

    Ioffe, Dmitry

    2011-01-01

    Self-attractive random walks undergo a phase transition in terms of the applied drift: If the drift is strong enough, then the walk is ballistic, whereas in the case of small drifts self-attraction wins and the walk is sub-ballistic. We show that, in any dimension at least 2, this transition is of first order. In fact, we prove that the walk is already ballistic at critical drifts, and establish the corresponding LLN and CLT.

  9. Ocean modelling aspects for drift applications

    Science.gov (United States)

    Stephane, L.; Pierre, D.

    2010-12-01

    Nowadays, many authorities in charge of rescue-at-sea operations lean on operational oceanography products to outline research perimeters. Moreover, current fields estimated with sophisticated ocean forecasting systems can be used as input data for oil spill/ adrift object fate models. This emphasises the necessity of an accurate sea state forecast, with a mastered level of reliability. This work focuses on several problems inherent to drift modeling, dealing in the first place with the efficiency of the oceanic current field representation. As we want to discriminate the relevance of a particular physical process or modeling option, the idea is to generate series of current fields of different characteristics and then qualify them in term of drift prediction efficiency. Benchmarked drift scenarios were set up from real surface drifters data, collected in the Mediterranean sea and off the coasts of Angola. The time and space scales that we are interested in are about 72 hr forecasts (typical timescale communicated in case of crisis), for distance errors that we hope about a few dozen of km around the forecast (acceptable for reconnaissance by aircrafts) For the ocean prediction, we used some regional oceanic configurations based on the NEMO 2.3 code, nested into Mercator 1/12° operational system. Drift forecasts were computed offline with Mothy (Météo France oil spill modeling system) and Ariane (B. Blanke, 1997), a Lagrangian diagnostic tool. We were particularly interested in the importance of the horizontal resolution, vertical mixing schemes, and any processes that may impact the surface layer. The aim of the study is to ultimately point at the most suitable set of parameters for drift forecast use inside operational oceanic systems. We are also motivated in assessing the relevancy of ensemble forecasts regarding determinist predictions. Several tests showed that mis-described observed trajectories can finally be modelled statistically by using uncertainties

  10. Longevity of Emplacement Drift Ground Support Materials

    Energy Technology Data Exchange (ETDEWEB)

    Tang, David H.

    2001-05-30

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for the selection of materials for ground support that will function throughout the preclosure period of a potential repository at Yucca Mountain. REV 01 ICN 01 of this analysis is developed in accordance with AP-3.10Q, Analyses and Models, Revision 2, ICN 4, and prepared in accordance with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M&O 2001a). The objective of this analysis is to update the previous analysis (CRWMS M&O 2000a) to account for related changes in the Ground Control System Description Document (CRWMS M&O 2000b), the Monitored Geologic Repository Project Description Document, which is included in the Requirements and Criteria for Implementing a Repository Design that can be Operated Over a Range of Thermal Modes (BSC 2001), input information, and in environmental conditions, and to provide updated information on candidate ground support materials. Candidate materials for ground support are carbon steel and cement grout. Steel is mainly used for steel sets, lagging, channel, rock bolts, and wire mesh. Cement grout is only considered in the case of grouted rock bolts. Candidate materials for the emplacement drift invert are carbon steel and granular natural material. Materials are evaluated for the repository emplacement drift environment based on the updated thermal loading condition and waste package design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground support materials for use in emplacement drifts. (2) Review existing documents concerning the behavior of candidate ground support materials during the preclosure period. (3) Evaluate impacts of temperature and radiation effects on mechanical and thermal properties of steel. Assess corrosion potential of steel at emplacement drift environment. (4) Evaluate factors

  11. Longevity of Emplacement Drift Ground Support Materials

    International Nuclear Information System (INIS)

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for the selection of materials for ground support that will function throughout the preclosure period of a potential repository at Yucca Mountain. REV 01 ICN 01 of this analysis is developed in accordance with AP-3.10Q, Analyses and Models, Revision 2, ICN 4, and prepared in accordance with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M and O 2001a). The objective of this analysis is to update the previous analysis (CRWMS M and O 2000a) to account for related changes in the Ground Control System Description Document (CRWMS M and O 2000b), the Monitored Geologic Repository Project Description Document, which is included in the Requirements and Criteria for Implementing a Repository Design that can be Operated Over a Range of Thermal Modes (BSC 2001), input information, and in environmental conditions, and to provide updated information on candidate ground support materials. Candidate materials for ground support are carbon steel and cement grout. Steel is mainly used for steel sets, lagging, channel, rock bolts, and wire mesh. Cement grout is only considered in the case of grouted rock bolts. Candidate materials for the emplacement drift invert are carbon steel and granular natural material. Materials are evaluated for the repository emplacement drift environment based on the updated thermal loading condition and waste package design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground support materials for use in emplacement drifts. (2) Review existing documents concerning the behavior of candidate ground support materials during the preclosure period. (3) Evaluate impacts of temperature and radiation effects on mechanical and thermal properties of steel. Assess corrosion potential of steel at emplacement drift environment. (4

  12. Ion mobility mass spectrometry of peptide, protein, and protein complex ions using a radio-frequency confining drift cell.

    Science.gov (United States)

    Allen, Samuel J; Giles, Kevin; Gilbert, Tony; Bush, Matthew F

    2016-02-01

    Ion mobility mass spectrometry experiments enable the characterization of mass, assembly, and shape of biological molecules and assemblies. Here, a new radio-frequency confining drift cell is characterized and used to measure the mobilities of peptide, protein, and protein complex ions. The new drift cell replaced the traveling-wave ion mobility cell in a Waters Synapt G2 HDMS. Methods for operating the drift cell and determining collision cross section values using this experimental set up are presented within the context of the original instrument control software. Collision cross sections for 349 cations and anions are reported, 155 of which are for ions that have not been characterized previously using ion mobility. The values for the remaining ions are similar to those determined using a previous radio-frequency confining drift cell and drift tubes without radial confinement. Using this device under 2 Torr of helium gas and an optimized drift voltage, denatured and native-like ions exhibited average apparent resolving powers of 14.2 and 16.5, respectively. For ions with high mobility, which are also low in mass, the apparent resolving power is limited by contributions from ion gating. In contrast, the arrival-time distributions of low-mobility, native-like ions are not well explained using only contributions from ion gating and diffusion. For those species, the widths of arrival-time distributions are most consistent with the presence of multiple structures in the gas phase. PMID:26739109

  13. Simplified Drift Analysis for Proving Lower Bounds in Evolutionary Computation

    DEFF Research Database (Denmark)

    Oliveto, Pietro S.; Witt, Carsten

    2011-01-01

    Drift analysis is a powerful tool used to bound the optimization time of evolutionary algorithms (EAs). Various previous works apply a drift theorem going back to Hajek in order to show exponential lower bounds on the optimization time of EAs. However, this drift theorem is tedious to read and to...

  14. Effectiveness of spray adjuvants on reduction of spray drift

    Science.gov (United States)

    Numerous drift reduction adjuvants and spray deposition aids are available to applicators of crop production and protection chemicals. Performance of many of the newly introduced drift control adjuvants has not been well documented for aerial application. Five new drift control adjuvants were sele...

  15. Compact drift-chambers for the OPAL forward detectors

    International Nuclear Information System (INIS)

    Two planes of four chambers are mounted in front of the forward calorimeter at each end of OPAL. Beam tests at CERN show good linearity (within 0.5 mm over 130 mm maximum drift) and good resolution in the drift direction (average 300 μm over the whole range of drift distances). The resolution along the wire is ±1 mm. (orig.)

  16. T cell precursor migration towards beta 2-microglobulin is involved in thymus colonization of chicken embryos

    DEFF Research Database (Denmark)

    Dunon, D; Kaufman, J; Salomonsen, J; Skjoedt, K; Vainio, O; Thiery, J P; Imhof, B A

    1990-01-01

    beta 2-microglobulin (beta 2m) attracts hemopoietic precursors from chicken bone marrow cells in vitro. The cell population responding to beta 2m increases during the second period of thymus colonization, which takes place at days 12-14 of incubation. The precursors from 13.5 day old embryos were...... which suggest that beta 2m mediated chemotaxis is involved in the second wave. Udgivelsesdato: 1990-Oct...

  17. Wave-induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    Science.gov (United States)

    Drivdal, M.; Broström, G.; Christensen, K. H.

    2014-12-01

    This study focuses on how wave-current and wave-turbulence interactions modify the transport of buoyant particles in the ocean. Here the particles can represent oil droplets, plastic particles, or plankton such as fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM), modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production, as well as the stronger veering by the Coriolis-Stokes force, affects the drift of the particles. The energy and momentum fluxes, as well as the Stokes drift, depend on the directional wave spectrum obtained from a wave model. As a first test, the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (i.e., classical Ekman theory). Secondly, the model is applied to a case in which we investigate the oil drift after an oil spill off the west coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by oil-drift models. In this case, using wind and wave forcing from the ERA Interim archive it is shown that the wave effects are important for the resultant drift and have the potential to improve drift forecasting.

  18. Drift mode accelerometry for spaceborne gravity measurements

    CERN Document Server

    Conklin, John W

    2014-01-01

    A drift mode accelerometer is a precision device that overcomes the much of the acceleration noise and readout dynamic range limitations of traditional electrostatic accelerometers. It has the potential of achieving acceleration noise performance of drag-free systems over a restricted frequency band without the need for external drag-free control or spacecraft propulsion. Like traditional accelerometers, the drift mode accelerometer contains a high-density test mass surrounded by an electrode housing, which can control and sense all six degrees of freedom of the test mass. Unlike traditional accelerometers, the suspension system is operated with a low duty cycle so that the limiting suspension force noise only acts over brief, known time intervals, which can be neglected in the data analysis. The readout is performed using a laser interferometer which is immune to the dynamic range limitations of even the best voltage references typically used to determine the inertial acceleration of electrostatic accelerome...

  19. The drift-flux correlation package MDS

    International Nuclear Information System (INIS)

    Based on the SONNENBURG drift-flux correlation, developed at GRS/Garching (Germany), a comprehensive drift-flux correlation package (MDS) has been established. Its aim is to support thermal-hydraulic mixture-fluid models, models being used for the simulation of the steady state and transient behaviour of characteristic thermal-hydraulic parameters of single- or two-phase fluids flowing along coolant channels of different types (being, e.g., parts of NPP-s, steam generators etc.). The characteristic properties of this package with respect to the behaviour at co- and counter-current flow, its inverse solutions needed for steady state simulations, its behaviour when approaching the lower or upper boundary of a two-phase region, its verification and behaviour with respect to other correlations will be discussed. An adequate driver code, MDSDRI, has been established too, allowing to test the package very thoroughly out of the complex thermal-hydraulic codes. (author)

  20. Passive appendages generate drift through symmetry breaking

    Science.gov (United States)

    Lācis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.

    2014-10-01

    Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals.

  1. Drift sight replacement in the U-2

    Science.gov (United States)

    Bialecki, Lawrence J.

    2005-05-01

    When first deployed in the mid 1950s, the U-2 had an inverted periscope (Drift Sight) to provide the pilot a view of the area below the aircraft. During a recent glass cockpit upgrade, this periscope was removed. This paper discusses: " The development activity leading up to flight test of an Electro Optical Viewsight System (EOVS) replacement for the Drift Sight. The impact and design consideration of using an inexpensive Commercial Off the Shelf (COTS) cameral module, originally designed for small hand held video cameras, " The process used to develop the basic requirements and how early input from the user community lead to an effective design (e.g.., Hand Grip), " The ruggedization techniques necessary to ensure the camera would meet the vibration, thermal, and Electro Magnetic Interface (EMI) environment, " Actual system performance data, " Growth "hooks" and how they were accommodated in a firm fixed price contract.

  2. Clean Industrial Room for Drift Tube Assembling

    CERN Document Server

    Glonti, GL; Evtoukhovitch, P G; Kroa, G; Manz, A; Potrap, I N; Rihter, P; Stoletov, G D; Tskhadadze, E G; Chepurnov, V F; Chirkov, A V; Shelkov, G A

    2001-01-01

    Description of a clean industrial room for assembly of drift tubes for the muon spectrometer of the ATLAS experiment is presented. High quality specifications on the detectors to be produced demanded creation of a workplace with stable temperature and humidity, as well as minimum quantity of dust in the room. Checking of parameters of intra-room air during long period of continuous work has been confirmed correctness of the designed characteristics of the climatic system installed in the clean room. The room large volum (\\sim 190 m^3), the powerful and flexible climatic system, and simplicity of service allow assembling of detectors with length up to 5 m. Subsequent checking of functionality of the assembled detectors has shown high quality of assembling (the amount of rejected tubes does not exceed 2 %). It demonstrates conformity to the assembling quality requirements for mass production of drift chambers for the muon spectrometer.

  3. Gas sensor with attenuated drift characteristic

    Science.gov (United States)

    Chen, Ing-Shin [Danbury, CT; Chen, Philip S. H. [Bethel, CT; Neuner, Jeffrey W [Bethel, CT; Welch, James [Fairfield, CT; Hendrix, Bryan [Danbury, CT; Dimeo, Jr., Frank [Danbury, CT

    2008-05-13

    A sensor with an attenuated drift characteristic, including a layer structure in which a sensing layer has a layer of diffusional barrier material on at least one of its faces. The sensor may for example be constituted as a hydrogen gas sensor including a palladium/yttrium layer structure formed on a micro-hotplate base, with a chromium barrier layer between the yttrium layer and the micro-hotplate, and with a tantalum barrier layer between the yttrium layer and an overlying palladium protective layer. The gas sensor is useful for detection of a target gas in environments susceptible to generation or incursion of such gas, and achieves substantial (e.g., >90%) reduction of signal drift from the gas sensor in extended operation, relative to a corresponding gas sensor lacking the diffusional barrier structure of the invention

  4. Review of cooling tower drift deposition models

    Energy Technology Data Exchange (ETDEWEB)

    Chen, N.C.J.

    1977-05-04

    The behavior, basic assumptions, and limitations of ten different models for calculating the drift deposition rate from wet cooling towers are reviewed and then their predicted results for such deposition with a common set of input parameters are compared. The predicted maximum deposition differs among the models by two orders of magnitude with a wide range in peak location. Comments and suggestions to improve the models are included.

  5. The 'Diogene' detector, 4π drift chamber

    International Nuclear Information System (INIS)

    'Diogene' is a detector with a solid angle near the steradian 4π, mainly comprising a drift chamber and capable of detecting in coincidence several tens of charged particles. Built by several laboratories (Dph-N/Saclay, CRN/Strasbourg and LPC/Clermont-Ferrand) it should be ready round about June 1980 to use the heavy ion beams of Saturne II for studying the multiple production of pions and protons in central collisions of relativistic heavy ions

  6. The drift table: designing for ludic engagement

    OpenAIRE

    Gaver, William; Bowers, John; Boucher, Andy; Gellerson, Hans; Pennington, Sarah; Schmidt, Albrecht; Steed, Anthony; Villar, Nicholas; Walker, Brendan

    2004-01-01

    The Drift Table is an electronic coffee table that displays slowly moving aerial photography controlled by the distribution of weight on its surface. It was designed to investigate our ideas about how technologies for the home could support ludic activities-that is, activities motivated by curiosity, exploration, and reflection rather than externally-defined tasks. The many design choices we made, for example to block or disguise utilitarian functionality, helped to articulate our emerging un...

  7. Average Drift Analysis and Population Scalability

    OpenAIRE

    He, Jun; Yao, Xin

    2013-01-01

    This paper aims to study how the population size affects the computation time of evolutionary algorithms in a rigorous way. The computation time of an evolutionary algorithm can be measured by either the expected number of generations (hitting time) or the expected number of fitness evaluations (running time) to find an optimal solution. Population scalability is the ratio of the expected hitting time between a benchmark algorithm and an algorithm using a larger population size. Average drift...

  8. FOMC Targets, Base Drift and Inflationary Expectations

    OpenAIRE

    Charles E. Hegji

    1989-01-01

    This paper uses a money supply-money demand model to study the effects on inflationary expectations of base drift and the Federal Open Market Committee's rebasing of its money supply targets. It is demonstrated that an averaging scheme for determining the Federal Open Market Committee's money stock target bases generates less inflationary uncertainty than no averaging. It is also shown that an alternative to target averaging is to accommodate long-run money supply strategy to changes in money...

  9. Redshift drift constraints on holographic dark energy

    OpenAIRE

    He, Dong-Ze; Zhang, Jing-Fei; Xin ZHANG

    2016-01-01

    The Sandage-Loeb (SL) test is a promising method for probing dark energy because it measures the redshift drift in the spectra of Lyman-$\\alpha$ forest of distant quasars, covering the "redshift desert" of $2\\lesssim z\\lesssim5$, which is not covered by existing cosmological observations. Therefore, it could provide an important supplement to current cosmological observations. In this paper, we explore the impact of SL test on the precision of cosmological constraints for two typical holograp...

  10. Continued Drift, but without the Acrimony

    DEFF Research Database (Denmark)

    Nielsen, Kristian L.

    2013-01-01

    If the measure of Barack Obama's success in mending US–European relations is whether the tone has improved, his presidency has been a great success. If the measure of success, however, is halting the drifting apart of policy preferences, the picture looks a lot less rosy. This article argues that....... The Obama administration realises that, and by this more limited measure, it has succeeded brilliantly....

  11. Inertial Orientation Trackers with Drift Compensation

    Science.gov (United States)

    Foxlin, Eric M.

    2008-01-01

    A class of inertial-sensor systems with drift compensation has been invented for use in measuring the orientations of human heads (and perhaps other, similarly sized objects). These systems can be designed to overcome some of the limitations of prior orientation-measuring systems that are based, variously, on magnetic, optical, mechanical-linkage, and acoustical principles. The orientation signals generated by the systems of this invention could be used for diverse purposes, including controlling head-orientation-dependent virtual reality visual displays or enabling persons whose limbs are paralyzed to control machinery by means of head motions. The inventive concept admits to variations too numerous to describe here, making it necessary to limit this description to a typical system, the selected aspects of which are illustrated in the figure. A set of sensors is mounted on a bracket on a band or a cap that gently but firmly grips the wearer s head to be tracked. Among the sensors are three drift-sensitive rotationrate sensors (e.g., integrated-circuit angular- rate-measuring gyroscopes), which put out DC voltages nominally proportional to the rates of rotation about their sensory axes. These sensors are mounted in mutually orthogonal orientations for measuring rates of rotation about the roll, pitch, and yaw axes of the wearer s head. The outputs of these rate sensors are conditioned and digitized, and the resulting data are fed to an integrator module implemented in software in a digital computer. In the integrator module, the angular-rate signals are jointly integrated by any of several established methods to obtain a set of angles that represent approximately the orientation of the head in an external, inertial coordinate system. Because some drift is always present as a component of an angular position computed by integrating the outputs of angular-rate sensors, the orientation signal is processed further in a drift-compensator software module.

  12. OpenDrift - an open source framework for ocean trajectory modeling

    Science.gov (United States)

    Dagestad, Knut-Frode; Breivik, Øyvind; Ådlandsvik, Bjørn

    2016-04-01

    We will present a new, open source tool for modeling the trajectories and fate of particles or substances (Lagrangian Elements) drifting in the ocean, or even in the atmosphere. The software is named OpenDrift, and has been developed at Norwegian Meteorological Institute in cooperation with Institute of Marine Research. OpenDrift is a generic framework written in Python, and is openly available at https://github.com/knutfrode/opendrift/. The framework is modular with respect to three aspects: (1) obtaining input data, (2) the transport/morphological processes, and (3) exporting of results to file. Modularity is achieved through well defined interfaces between components, and use of a consistent vocabulary (CF conventions) for naming of variables. Modular input implies that it is not necessary to preprocess input data (e.g. currents, wind and waves from Eulerian models) to a particular file format. Instead "reader modules" can be written/used to obtain data directly from any original source, including files or through web based protocols (e.g. OPeNDAP/Thredds). Modularity of processes implies that a model developer may focus on the geophysical processes relevant for the application of interest, without needing to consider technical tasks such as reading, reprojecting, and colocating input data, rotation and scaling of vectors and model output. We will show a few example applications of using OpenDrift for predicting drifters, oil spills, and search and rescue objects.

  13. A Standard Law for the Equatorward Drift of the Sunspot Zones

    Science.gov (United States)

    Hathaway, David H.

    2012-01-01

    The latitudinal location of the sunspot zones in each hemisphere is determined by calculating the centroid position of sunspot areas for each solar rotation from May 1874 to June 2012. When these centroid positions are plotted and analyzed as functions of time from each sunspot cycle maximum there appears to be systematic differences in the positions and equatorward drift rates as a function of sunspot cycle amplitude. If, instead, these centroid positions are plotted and analyzed as functions of time from each sunspot cycle minimum then most of the differences in the positions and equatorward drift rates disappear. The differences that remain disappear entirely if curve fitting is used to determine the starting times (which vary by as much as 8 months from the times of minima). The sunspot zone latitudes and equatorward drift measured relative to this starting time follow a standard path for all cycles with no dependence upon cycle strength or hemispheric dominance. Although Cycle 23 was peculiar in its length and the strength of the polar fields it produced, it too shows no significant variation from this standard. This standard law, and the lack of variation with sunspot cycle characteristics, is consistent with Dynamo Wave mechanisms but not consistent with current Flux Transport Dynamo models for the equatorward drift of the sunspot zones.

  14. A hyper-ensemble forecast of surface drift

    Science.gov (United States)

    Vandenbulcke, L.; Lenartz, F.; Poulain, P. M.; Rixen, M.; DART Consortium; MREA Consortium

    2009-04-01

    The prediction of surface drift of water is an important task, with applications such as marine transport, pollutant dispersion, and search-and-rescue activities. However, it is also very challenging, because it depends on ocean models that (usually) do not completely accurately represent wind-induced current, that do not include wave-driven currents, etc. However, the real surface drift depends on all present physical phenomena, which moreover interact in complex ways. Furthermore, although each of these factors can be forecasted by deterministic models, the latter all suffer from limitations, resulting in imperfect predictions. In the present study, we try and predict the drift of buoys launched during the DART06 (Dynamics of the Adriatic sea in Real-Time 2006) and MREA07 (Maritime Rapid Environmental Assessment 2007) sea trials, using the so-called hyper-ensemble technique: different models are combined in order to minimize departure from independent observations during a training period. The obtained combination is then used in forecasting mode. We review and try out different hyper-ensemble techniques, such as the simple ensemble mean, least-squares weighted linear combinations, and techniques based on data assimilation, which dynamically update the model's weights in the combination when new observations become available. We show that the latter methods alleviate the need of a priori fixing the training length. When the forecast period is relatively short, the discussed methods lead to much smaller forecasting errors compared with individual models (at least 3 times smaller), with the dynamic methods leading to the best results. When many models are available, errors can be further reduced by removing colinearities between them by performing a principal component analysis. At the same time, this reduces the amount of weights to be determined. In complex environments, the skill of individual models may vary over time periods smaller than the desired

  15. Longevity of Emplacement Drift Ground Support Materials

    International Nuclear Information System (INIS)

    The purpose of this analysis is to evaluate the factors affecting the longevity of emplacement drift ground support materials and to develop a basis for selection of materials for ground support that will function throughout the preclosure period. The Development Plan (DP) for this analysis is given in CRWMS M and O (Civilian Radioactive Waste Management System Management and Operating Contractor) (1999a). The candidate materials for ground support are steel (carbon steel, ductile cast iron, galvanized steel, and stainless steel, etc.) and cement. Steel will mainly be used for steel sets, lagging, channels, rock bolts, and wire mesh. Cement usage is only considered in the case of grouted rock bolts. The candidate materials for the invert structure are steel and crushed rock ballast. The materials shall be evaluated for the repository emplacement drift environment under a specific thermal loading condition based on the proposed License Application Design Selection (LADS) design. The analysis consists of the following tasks: (1) Identify factors affecting the longevity of ground control materials for use in emplacement drifts. (2) Review existing documents concerning behavior of candidate ground control materials during the preclosure period. The major criteria to be considered for steel are mechanical and thermal properties, and durability, of which corrosion is the most important concern. (3) Evaluate the available results and develop recommendations for material(s) to be used

  16. Monitored Drift Chambers in the ATLAS Detector

    CERN Multimedia

    Herten, G

    Monitored Drift Chambers (MDT) are used in the ATLAS Detector to measure the momentum of high energy muons. They consist of drift tubes, which are filled with an Ar-CO2 gas mixture at 3 bar gas pressure. About 1200 drift chambers are required for ATLAS. They are up to 6 m long. Nevertheless the position of every wire needs to be known with a precision of 20 µm within a chamber. In addition, optical alignment sensors are required to measure the relative position of adjacent chambers with a precision of 30µm. This gigantic task seems impossible at first instance. Indeed it took many years of R&D to invent the right tools and methods before the first chamber could be built according to specifications. Today, at the time when 50% of the chambers have been produced, we are confident that the goal for ATLAS can be reached. The mechanical precision of the chambers could be verified with the x-ray tomograph at CERN. This ingenious device, developed for the MDT system, is able to measure the wire position insid...

  17. Sunrise enhancement of equatorial vertical plasma drift

    Science.gov (United States)

    Liu, Libo; Zhang, Ruilong; Le, Huijun

    2016-04-01

    Sunrise enhancement in vertical plasma drift over equatorial regions is not discernible in the statistical picture compared with the significant enhancement during dusk hours. In this report, it is the first time to investigate the occurrence of the dawn enhancement in the equatorial ionospheric vertical plasma drift from ROCSAT-1 observations during geomagnetic quiet times. The dawn enhancements occur most frequently in June solstice and least frequently in December solstice. The statistical survey shows that the occurrence depends on the magnetic declination. The enhancement has the strongest amplitude in regions near 320° longitude and peaks during June solstice. The dawn enhancement reaches its peak after the sunrise in conjugated E regions. Furthermore, it is found that the dawn enhancement is closely related to the difference between the sunrise times in the conjugated E regions (sunrise time lag). The dawn enhancement occurs easily in regions with a large sunrise time lag. Moreover, we will report the effects of the sunrise enhancement of vertical plasma drift on the equatorial ionosphere as indicated from the observations and model simulations. We thanks National Central University of Taiwan providing the ROCSAT-1 data. The Ap and F107 indices are obtained from the National Geophysical Data Center (http://spidr.ngdc.noaa.gov/spidr/). This research is supported by National Natural Science Foundation of China (41231065), the Chinese Academy of Sciences project (KZZD-EW-01-3), National Key Basic Research Program of China (2012CB825604) and National Natural Science Foundation of China (41321003).

  18. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    Directory of Open Access Journals (Sweden)

    ABDELAZIZ BEDDIAF

    2016-03-01

    Full Text Available The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FEA made in COMSOL. The model solved by COMSOL environment takes into account the entire sensor and thermal effects due to the temperature considering the materials’ properties, the geometric shape and also the heat transfer mechanisms. By COMSOL we determine how the temperature affects the sensor during the manufacturing process. For that end, we calculated the thermal drift of capacitance at rest, the thermal coefficients and we compared them with experimental results to validate our model. Further, we studied the thermal drift of sensor characteristics both at rest and under constant and uniform pressure. Further, our study put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. Finally, this study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the geometrical parameters.

  19. Correlated Energy Exchange in Drifting Sea Ice

    Directory of Open Access Journals (Sweden)

    A. Chmel

    2011-01-01

    Full Text Available The ice floe speed variations were monitored at the research camp North Pole 35 established on the Arctic ice pack in 2008. A three-month time series of measured speed values was used for determining changes in the kinetic energy of the drifting ice floe. The constructed energy distributions were analyzed by methods of nonextensive statistical mechanics based on the Tsallis statistics for open nonequilibrium systems, such as tectonic formations and drifting sea ice. The nonextensivity means the nonadditivity of externally induced energy changes in multicomponent systems due to dynamic interrelation of components having no structural links. The Tsallis formalism gives one an opportunity to assess the correlation between ice floe motions through a specific parameter, the so-called parameter of nonextensivity. This formalistic assessment of the actual state of drifting pack allows one to forecast some important trends in sea ice behavior, because the level of correlated dynamics determines conditions for extended mechanical perturbations in ice pack. In this work, we revealed temporal fluctuations of the parameter of nonextensivity and observed its maximum value before a large-scale sea ice fragmentation (faulting of consolidated sea ice. The correlation was not detected in fragmented sea ice where long-range interactions are weakened.

  20. Internal Clock Drift Estimation in Computer Clusters

    Directory of Open Access Journals (Sweden)

    Hicham Marouani

    2008-01-01

    Full Text Available Most computers have several high-resolution timing sources, from the programmable interrupt timer to the cycle counter. Yet, even at a precision of one cycle in ten millions, clocks may drift significantly in a single second at a clock frequency of several GHz. When tracing the low-level system events in computer clusters, such as packet sending or reception, each computer system records its own events using an internal clock. In order to properly understand the global system behavior and performance, as reported by the events recorded on each computer, it is important to estimate precisely the clock differences and drift between the different computers in the system. This article studies the clock precision and stability of several computer systems, with different architectures. It also studies the typical network delay characteristics, since time synchronization algorithms rely on the exchange of network packets and are dependent on the symmetry of the delays. A very precise clock, based on the atomic time provided by the GPS satellite network, was used as a reference to measure clock drifts and network delays. The results obtained are of immediate use to all applications which depend on computer clocks or network time synchronization accuracy.

  1. Comparison of drift velocities of nighttime equatorial plasma depletions with ambient plasma drifts and thermospheric neutral winds

    NARCIS (Netherlands)

    Liu, G.; England, S.L.; Frey, H.U.; Immel, T.J.; Lin, C.S.; Pacheco, E.E.; Häusler, K.; Doornbos, E.N.

    2013-01-01

    This is the first study to compare plasma depletion drifts with the ambient plasma drifts and neutral winds in the post sunset equatorial ionosphere using global-scale satellite observations. The local time and latitude variations of the drift velocities of O+ plasma depletions at 350–400 km altitud

  2. Concept of a solid-state drift chamber

    International Nuclear Information System (INIS)

    The operation of a solid state drift chamber is described, and its use in a high rate, high multiplicity environment is discussed. The Solid State Drift Chamber (SSDCH) is a thin wafer of a high purity n-type silicon (few cm2 x a few hundreds μm thick) with a single small-area, small-capacitance anode readout. The drift voltage is supplied to an array of drift electrodes on both sides of the wafer to produce a uniform drift field parallel to the surface of the wafer and to ensure the complete depletion of the wafer

  3. Hydroelastic responses of pontoon type very large floating offshore structures. 2nd Report. Effect of the water depth and the drift forces; Pontoon gata choogata futaishiki kaiyo kozobutsu no harochu chosei oto ni kansuru kenkyu. 2. Senkai eikyo to hyoryuryoku

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, H.; Miyajima, S. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science; Masuda, K.; Ikoma, T. [Nihon University, Tokyo (Japan). College of Science and Technology

    1996-12-31

    Steady-state drift force in regular waves is theoretically analyzed. It is also studied under combined external force experimentally using a two-dimensional water tank. The fluid forces are analyzed by the pressure distribution method based on the potential theory, in which the effects of water depth are taken into account to discuss the effects of elastic deformation of the floating structure on the drift characteristics of steady-state waves. The tests were carried out using a wave-making circulating water tank equipped with a wind duct to create wind, waves and tidal flow. Drift force under a combined external force by wind, wave and/or tidal flow cannot be accurately predicted by arithmetically adding these components. For predicting drift force by tidal flow, it is necessary to take into account drag force in current at the floating structure bottom as well as that in wind at the front face. Drift force by tidal flow is affected by shallowness of water, which should be taken into account for drag forces. The floating structure will be deformed along the wave face as its stiffness decreases, basically decreasing steady-state drift force. 9 refs., 14 figs.

  4. Ground Control for Emplacement Drifts for SR

    International Nuclear Information System (INIS)

    This analysis demonstrates that a satisfactory ground control system can be designed for the Yucca Mountain site, and provides the technical basis for the design of ground support systems to be used in repository emplacement and non-emplacement drifts. The repository ground support design was based on analytical methods using acquired computer codes, and focused on the final support systems. A literature review of case histories, including the lessons learned from the design and construction of the ESF, the studies on the seismic damages of underground openings, and the use of rock mass classification systems in the ground support design, was conducted (Sections 6.3.4 and 6.4). This review provided some basis for determining the inputs and methodologies used in this analysis. Stability of the supported and unsupported emplacement and non-emplacement drifts was evaluated in this analysis. The excavation effects (i.e., state of the stress change due to excavation), thermal effects (i.e., due to heat output from waste packages), and seismic effects (i.e., from potential earthquake events) were evaluated, and stress controlled modes of failure were examined for two in situ stress conditions (k0=0.3 and 1.0) using rock properties representing rock mass categories of 1 and 5. Variation of rock mass units such as the non-lithophysal (Tptpmn) and lithophysal (Tptpll) was considered in the analysis. The focus was on the non-lithophysal unit because this unit appears to be relatively weaker and has much smaller joint spacing. Therefore, the drift stability and ground support needs were considered to be controlled by the design for this rock unit. The ground support systems for both emplacement and non-emplacement drifts were incorporated into the models to assess their performance under in situ, thermal, and seismic loading conditions. Both continuum and discontinuum modeling approaches were employed in the analyses of the rock mass behavior and in the evaluation of the

  5. In-Drift Precipitates/Salts Analysis

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2001-01-10

    As directed by a written development plan (CRWMS M&O 1999a), an analysis of the effects of salts and precipitates on the repository chemical environment is to be developed and documented in an Analyses/Model Report (AMR). The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The purpose of this ICN is to qualify and document qualification of the AMR's technical products. The scope of this document is to develop a model of the processes that govern salt precipitation and dissolution and resulting water composition in the Engineered Barrier System (EBS). This model is developed to serve as a basis for the in-drift geochemical modeling work performed by PAO and is to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. However, the concepts may also apply to some near and far field geochemical processes and can have conceptual application within the unsaturated zone and saturated zone transport modeling efforts. The intended use of the model developed in this report is to estimate, within an appropriate level of confidence, the pH, chloride concentration, and ionic strength of water on the drip shield or other location within the drift during the post-closure period. These estimates are based on evaporative processes that are subject to a broad range of potential environmental conditions and are independent of the presence or absence of backfill. An additional intended use is to estimate the environmental conditions required for complete vaporization of water. The presence and composition of liquid water

  6. Abstraction of Drift-Scale Coupled Processes

    International Nuclear Information System (INIS)

    This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M andO 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period

  7. Airborne organophosphate pesticides drift in Mediterranean climate: The importance of secondary drift

    Science.gov (United States)

    Zivan, Ohad; Segal-Rosenheimer, Michal; Dubowski, Yael

    2016-02-01

    Pesticide application is a short-term air-pollution episode with near and far field effects due to atmospheric drift. In order to better evaluate resulting air concentrations in nearby communities following pesticide application, measurements of airborne pesticides were conducted at ∼70 m from field edge. This was done following three different application events of the organophosphate pesticide Chlorpyrifos in a persimmon orchard. Complementary information on larger spatial scale was obtained using CALPUFF modeling in which application and meteorological data was used to better evaluate dispersion patterns. Measurements indicated high airborne concentrations during application hours (few μg m-3 for 8 h average), which dropped to tens of ng m-3 in the following days. Measured atmospheric concentrations show that secondary drift (i.e., post-application drift) involves significant loads of pesticides and hence should not be ignored in exposure considerations. Furthermore, CALPUFF modeling revealed the complex dispersion pattern when weak winds prevailed, and showed that during the 24 h after application air concentrations reached levels above the hourly Texas effect screening level (0.1 μg m-3). Interestingly, weak winds on the night after application resulted in a secondary peak in measured and modeled air concentrations. Long exposure time (when secondary drift is considered) and concentrations measured following such common air-assisted orchard application, suggest pesticide drift may have health repercussions that are currently unknown, and emphasize the need for further epidemiological studies.

  8. Disturbance electric field effects on equatorial evening vertical drift and spread F development

    International Nuclear Information System (INIS)

    Complete text of publication follows. The most studied and perhaps the most readily verifiable precursor condition for the growth of post sunset equatorial plasma instabilities leading to spread F irregularity (ESF) development is the prereversal enhancement in the zonal electric field (PRE). Its day-to-day, seasonal and solar flux dependent variabilities are to the first degree responsible for the corresponding variabilities in ESF. The day-to-day variability which is the most challenging problem results from upward propagating atmospheric waves (especially, gravity- and planetary- waves) as well as from disturbance electric fields arising from weak to intense substorm/magnetic storm disturbances. Recent studies have shown that the evening F region vertical drift/PRE and hence the ESF suffers drastic modifications due to under-shielding as well as over-shielding electric fields. The PRE can undergo large increase, decrease, total suppression or even reversal to downward depending upon the polarity and intensity of the prompt penetrating zonal electric field. While the ESF intensity follows in general moderate increase in the PRE it does not follow very large increases in vertical drift. This paper will present results from recent investigations, mainly based on Digisonde observations in Brazil, on the evening vertical drift and ESF day-to-day variabilities arising from magnetospheric- and atmospheric- forcing.

  9. Radon in the DRIFT-II directional dark matter TPC: emanation, detection and mitigation

    CERN Document Server

    Battat, J B R; Daw, E; Dorofeev, A; Ezeribe, A C; Fox, J R; Gauvreau, J -L; Gold, M; Harmon, L J; Harton, J L; Landers, J M; Lee, E R; Loomba, D; Matthews, J A J; Miller, E H; Monte, A; Murphy, A StJ; Paling, S M; Phan, N; Pipe, M; Robinson, M; Sadler, S W; Scarff, A; Snowden-Ifft, D P; Spooner, N J C; Telfer, S; Walker, D; Warner, D; Yuriev, L

    2014-01-01

    Radon gas emanating from materials is of interest in environmental science and also a major concern in rare event non-accelerator particle physics experiments such as dark matter and double beta decay searches, where it is a major source of background. Notable for dark matter experiments is the production of radon progeny recoils (RPRs), the low energy (~100 keV) recoils of radon daughter isotopes, which can mimic the signal expected from WIMP interactions. Presented here are results of measurements of radon emanation from detector materials in the 1 metre cubed DRIFT-II directional dark matter gas time projection chamber experiment. Construction and operation of a radon emanation facility for this work is described, along with an analysis to continuously monitor DRIFT data for the presence of internal 222Rn and 218Po. Applying this analysis to historical DRIFT data, we show how systematic substitution of detector materials for alternatives, selected by this device for low radon emanation, has resulted in a f...

  10. Koedam {beta} factors revisited

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J.E. [Physics Department, University of Wisconsin, Madison, WI (United States); Doughty, D.A. [Perkin-Elmer Optoelectronics, Santa Clara, CA (United States); Lister, G.G. [OSRAM SYLVANIA Inc., Beverly, MA (United States)

    2002-07-21

    A Koedam {beta} factor makes it possible to compute the total output power in line radiation from a positive column discharge using a single radiance measurement normal to an aperture in the wall. The results of analytic derivations of {beta} factors are presented for columns with uniform ({beta}=1.0) and parabolic ({beta}=0.75) excitation rates per unit volume and with negligible opacity. A Monte Carlo code for simulating radiation trapping with a spatially uniform density of absorbing atoms is then used to determine {beta} factors as a function of opacity. The code includes partial frequency redistribution and a Voigt line shape with radiative broadening, resonance collisional broadening, and Doppler broadening. The resulting {beta} factors are found to be nearly independent of opacity over a wide range of column radii for spectral line shapes dominated by Doppler broadening or by resonance collisional broadening. Additional Monte Carlo simulations are used to study {beta} factors as a function of a non-uniform density of absorbing atoms from radial cataphoresis with line shapes dominated by Doppler broadening, foreign gas broadening, and resonance collisional broadening. Radial cataphoresis is found to increase {beta} factors in all cases. Geometrical effects, refraction, and imperfect transmission at the glass wall are studied and found to decrease {beta} factors. (author)

  11. Beta-energy averaging and beta spectra

    International Nuclear Information System (INIS)

    A simple yet highly accurate method for approximately calculating spectrum-averaged beta energies and beta spectra for radioactive nuclei is presented. This method should prove useful for users who wish to obtain accurate answers without complicated calculations of Fermi functions, complex gamma functions, and time-consuming numerical integrations as required by the more exact theoretical expressions. Therefore, this method should be a good time-saving alternative for investigators who need to make calculations involving large numbers of nuclei (e.g., fission products) as well as for occasional users interested in restricted number of nuclides. The average beta-energy values calculated by this method differ from those calculated by ''exact'' methods by no more than 1 percent for nuclides with atomic numbers in the 20 to 100 range and which emit betas of energies up to approximately 8 MeV. These include all fission products and the actinides. The beta-energy spectra calculated by the present method are also of the same quality

  12. Neutrinoless double beta decay experiment DCBA using a magnetic momentum-analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, N., E-mail: nobuhiro.ishihara@kek.jp [High Energy Accelerator Research Organization (KEK), Tsukuba, 305-0801 (Japan); Kato, Y.; Inagaki, T.; Ohama, T.; Takeda, S.; Yamada, Y. [High Energy Accelerator Research Organization (KEK), Tsukuba, 305-0801 Japan (Japan); Ukishima, N.; Teramoto, Y. [Osaka City University, Sumiyoshi, Osaka, 558-8585 (Japan); Morishima, Y.; Nakano, I. [Okayama University, Okayama, 700-8530 (Japan); Kitamura, S. [Tokyo Metropolitan University, Arakawa, Tokyo, 116-8551 (Japan); Sakamoto, Y. [Tohoku Gakuin University, Izumi, Sendai, 981-3193 (Japan); Nagasaka, Y. [Hiroshima Institute of Technology, Saeki, Hiroshima, 731-5193 (Japan); Tamura, N. [Niigata University, Niigata, 950-2181 (Japan); Tanaka, K. [BTE, Minato, Tokyo, 105-0011 (Japan); Ito, R. [ZTJ, Chiyoda, Tokyo, 101-0047 (Japan)

    2011-12-15

    A magnetic momentum-analyzer is being developed at KEK for neutrinoless double beta decay experiment called DCBA (Drift Chamber Beta-ray Analyzer, inverted ABCD). A lot of thin plates of {sup 150}Nd compound are installed in tracking detectors located in a uniform magnetic field. The three-dimensional position information is obtained for the helical track of a beta ray. More R and D will be studied using the second test apparatus DCBA-T2, which is now under construction.

  13. Wave induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    Science.gov (United States)

    Drivdal, M.; Broström, G.; Christensen, K. H.

    2014-05-01

    The modelling of wave-current and wave-turbulence interactions have received much attention in recent years. In this study the focus is on how these wave effects modify the transport of particles in the ocean. Here the particles are buoyant tracers that can represent oil droplets, plastic particles or plankton, for example fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM), modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production as well as the stronger veering by the Coriolis-Stokes force affect the drift of the particles. The energy and momentum fluxes as well as the Stokes drift depend on the directional wave spectrum that can be obtained from a wave model or from observations. As a first test the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (e.g. classical Ekman theory). Secondly the model is applied to a case where we investigate the oil drift after an offshore oil spill outside the western coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by empirical models. With wind and wave forcing from the ERA Interim archive, it is shown that the wave effects are important for the resultant drift in this case, and has the potential to improve drift forecasting.

  14. Wave induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    Directory of Open Access Journals (Sweden)

    M. Drivdal

    2014-05-01

    Full Text Available The modelling of wave-current and wave-turbulence interactions have received much attention in recent years. In this study the focus is on how these wave effects modify the transport of particles in the ocean. Here the particles are buoyant tracers that can represent oil droplets, plastic particles or plankton, for example fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM, modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production as well as the stronger veering by the Coriolis–Stokes force affect the drift of the particles. The energy and momentum fluxes as well as the Stokes drift depend on the directional wave spectrum that can be obtained from a wave model or from observations. As a first test the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (e.g. classical Ekman theory. Secondly the model is applied to a case where we investigate the oil drift after an offshore oil spill outside the western coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by empirical models. With wind and wave forcing from the ERA Interim archive, it is shown that the wave effects are important for the resultant drift in this case, and has the potential to improve drift forecasting.

  15. Remote sensing of seawater and drifting ice in Svalbard fjords by compact Raman LIDAR

    CERN Document Server

    Bunkin, Alexey F; Lednev, Vasily N; Lushnikov, Dmitry L; Marchenko, Aleksey V; Morozov, Eugene G; Pershin, Sergey M; Yulmetov, Renat N

    2013-01-01

    A compact Raman LIDAR system for remote sensing of sea and drifting ice was developed at the Wave Research Center at the Prokhorov General Physics Institute of the RAS. The developed system is based on a diode pumped solid state YVO4:Nd laser combined with compact spectrograph equipped with gated detector. The system exhibits high sensitivity and can be used for mapping or depth profiling of different parameters within many oceanographic problems. Light weight (~20 kg) and low power consumption (300 W) make possible to install the device on any vehicle including unmanned aircraft or submarine system. The Raman LIDAR presented was used for Svalbard fjords study and analysis of different influence of the open sea and glaciers on the water properties. Temperature, phytoplankton, and dissolved organic matter distributions in the seawater were studied in the Ice Fjord, Van Mijen Fjord and Rinders Fjord. Drifting ice and seawater in the Rinders Fjord were characterized by the Raman spectroscopy and fluorescence. It...

  16. Deterministic drift instability and stochastic thermal perturbations of magnetic dissipative droplet solitons

    Science.gov (United States)

    Wills, P.; Iacocca, E.; Hoefer, M. A.

    2016-04-01

    The magnetic dissipative droplet is a strongly nonlinear wave structure that can be stabilized in a thin film ferromagnet exhibiting perpendicular magnetic anisotropy by use of spin transfer torque. These structures have been observed experimentally at room temperature, showcasing their robustness against noise. Here, we quantify the effects of thermal noise by deriving stochastic equations of motion for a droplet based on soliton perturbation theory. First, it is found that deterministic droplets are linearly unstable at large bias currents, subject to a drift instability. When the droplet is linearly stable, our framework allows us to analytically compute the droplet's generation linewidth and center variance. Additionally, we study the influence of nonlocal and Oersted fields with micromagnetic simulations, providing insight into their effect on the generation linewidth. These results motivate detailed experiments on the current and temperature-dependent linewidth as well as drift instability statistics of droplets, which are important figures-of-merit in the prospect of droplet-based applications.

  17. Noncommutative Einstein-Maxwell pp-waves

    OpenAIRE

    Ruiz Ruiz, Fernando; Marculescu, S.

    2006-01-01

    The field equations coupling a Seiberg-Witten electromagnetic field to noncommutative gravity, as described by a formal power series in the noncommutativity parameters $\\theta^{\\alpha\\beta}$, is investigated. A large family of solutions, up to order one in $\\theta^{\\alpha\\beta}$, describing Einstein-Maxwell null pp-waves is obtained. The order-one contributions can be viewed as providing noncommutative corrections to pp-waves. In our solutions, noncommutativity enters the spacetime metric thr...

  18. Weak interaction studies from nuclear beta decay

    International Nuclear Information System (INIS)

    The studies performed at the theoretical nuclear physics division of the Laboratory of Nuclear Studies, Osaka University, are reported. Electron spin density and internal conversion process, nuclear excitation by electron transition, beta decay, weak charged current, and beta-ray angular distributions in oriented nuclei have been studied. The relative intensity of internal conversion electrons for the case in which the radial wave functions of orbital electrons are different for electron spin up and down was calculated. The calculated value was in good agreement with the experimental one. The nuclear excitation following the transition of orbital electrons was studied. The calculated probability of the nuclear excitation of Os189 was 1.4 x 10-7 in conformity with the experimental value 1.7 x 10-7. The second class current and other problems on beta-decay have been extensively studied, and described elsewhere. Concerning weak charged current, the effects of all induced terms, the time component of main axial vector, all partial waves of leptons, Coulomb correction for the electrons in finite size nuclei, and radiative correction were studied. The beta-ray angular distribution for the 1+ -- 0+ transition in oriented B12 and N12 was investigated. In this connection, investigation on the weak magnetism to include all higher order corrections for the evaluation of the spectral shape factors was performed. Other works carried out by the author and his collaborators are also explained. (Kato, T.)

  19. Penetration of lower hybrid current drive waves in tokamaks

    International Nuclear Information System (INIS)

    Lower hybrid (LH) ray propagation in toroidal plasma is shown to be controlled by combination of the azimuthal spectrum launched by the antenna, the poloidal variation of the magnetic field, and the scattering of the waves by the drift wave fluctuations. The width of the poloidal and radial radio frequency wave spectrum increases rapidly as the rays penetrate into higher density and scatter from the drift waves. The electron temperature gradient (ETG) spectrum is particularly effective in scattering the LH waves due to its comparable wavelengths and phase velocities. ETG turbulence is also driven by the radial gradient of the electron current profile giving rise to an anomalous viscosity spreading the LH driven plasma currents. The LH wave scattering is derived from a Fokker-Planck equation for the distribution of the ray trajectories with diffusivities derived from the drift wave fluctuations. The condition for chaotic diffusion for the rays is derived. The evolution of the poloidal and radial mode number spectrum of the lower hybrid waves are both on the antenna spectrum and the spectrum of the drift waves. Antennas launching higher poloidal mode number spectra drive off-axis current density profiles producing negative central shear [RS] plasmas with improved thermal confinement from ETG transport. Core plasma current drive requires antennas with low azimuthal mode spectra peaked at m = 0 azimuthal mode numbers

  20. Penetration of lower hybrid current drive waves in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Horton, W. [The University of Texas at Austin, Austin, Texas 78712 (United States); Aix-Marseille University, 58, Bd Charles Livon, 13284 Marseille (France); Goniche, M.; Peysson, Y.; Decker, J.; Ekedahl, A.; Litaudon, X. [CEA, IRFM, F-13108 Saint-Paul-Lez Durance (France)

    2013-11-15

    Lower hybrid (LH) ray propagation in toroidal plasma is shown to be controlled by combination of the azimuthal spectrum launched by the antenna, the poloidal variation of the magnetic field, and the scattering of the waves by the drift wave fluctuations. The width of the poloidal and radial radio frequency wave spectrum increases rapidly as the rays penetrate into higher density and scatter from the drift waves. The electron temperature gradient (ETG) spectrum is particularly effective in scattering the LH waves due to its comparable wavelengths and phase velocities. ETG turbulence is also driven by the radial gradient of the electron current profile giving rise to an anomalous viscosity spreading the LH driven plasma currents. The LH wave scattering is derived from a Fokker-Planck equation for the distribution of the ray trajectories with diffusivities derived from the drift wave fluctuations. The condition for chaotic diffusion for the rays is derived. The evolution of the poloidal and radial mode number spectrum of the lower hybrid waves are both on the antenna spectrum and the spectrum of the drift waves. Antennas launching higher poloidal mode number spectra drive off-axis current density profiles producing negative central shear [RS] plasmas with improved thermal confinement from ETG transport. Core plasma current drive requires antennas with low azimuthal mode spectra peaked at m = 0 azimuthal mode numbers.

  1. Instrumentation system for determination and compensation of electro-optic modulator transfer function drift

    International Nuclear Information System (INIS)

    This paper presents an instrumentation system developed to improve the operation of an electro-optic modulator (EOM). During their operating time, EOM are subject to a drift of the optical transfer function; therefore the initial tuning of the bias point no longer corresponds to the best characteristics of the device. Because of this drift the EOM no longer behaves linearly and there is degradation during time of the performances of the system in which the EOM is included. To determine the drift, a low frequency modulation signal (at 500 Hz) is applied to the EOM and the second harmonic component at 1 kHz is detected. A new criterion is introduced for estimating the nonlinearity and for compensating the drift of the transfer function, keeping the optical bias point at the quadrature position. Temperature changes significantly influence the EOM characteristics. Thus, the instrumentation system has to be simultaneously developed with temperature control and drift compensation of the optical transfer function. The design is based on PSOC microcontrollers for tuning the different parameters, for data acquisition and regulation process. By setting the temperature to some specific values, it is possible to test the behaviour of the modulator. Finally, by using both temperature and bias point control, a significant reduction of the nonlinearity can be obtained during 2 h of experiment: the biasing point at the quadrature point of the transfer function which corresponds to the most linear behaviour can be stabilized within ±0.22% of the half-wave voltage. All the works presented here were carried out with a Mach–Zehnder intensity modulator made of lithium niobate, but it is also possible to apply this method to other kinds of material, for example polymer material

  2. Instrumentation system for determination and compensation of electro-optic modulator transfer function drift

    Science.gov (United States)

    Thanh Bui, Dang; Thanh Nguyen, Chi; Ledoux-Rak, Isabelle; Zyss, Joseph; Journet, Bernard

    2011-12-01

    This paper presents an instrumentation system developed to improve the operation of an electro-optic modulator (EOM). During their operating time, EOM are subject to a drift of the optical transfer function; therefore the initial tuning of the bias point no longer corresponds to the best characteristics of the device. Because of this drift the EOM no longer behaves linearly and there is degradation during time of the performances of the system in which the EOM is included. To determine the drift, a low frequency modulation signal (at 500 Hz) is applied to the EOM and the second harmonic component at 1 kHz is detected. A new criterion is introduced for estimating the nonlinearity and for compensating the drift of the transfer function, keeping the optical bias point at the quadrature position. Temperature changes significantly influence the EOM characteristics. Thus, the instrumentation system has to be simultaneously developed with temperature control and drift compensation of the optical transfer function. The design is based on PSOC microcontrollers for tuning the different parameters, for data acquisition and regulation process. By setting the temperature to some specific values, it is possible to test the behaviour of the modulator. Finally, by using both temperature and bias point control, a significant reduction of the nonlinearity can be obtained during 2 h of experiment: the biasing point at the quadrature point of the transfer function which corresponds to the most linear behaviour can be stabilized within ±0.22% of the half-wave voltage. All the works presented here were carried out with a Mach-Zehnder intensity modulator made of lithium niobate, but it is also possible to apply this method to other kinds of material, for example polymer material.

  3. Development of an equipment diagnostic system that evaluates sensor drift

    International Nuclear Information System (INIS)

    The importance of condition monitoring technology for equipment has increased with the introduction of condition-based maintenance in nuclear power plants. We are developing a diagnostic system using process signals for plant equipment, such as pumps and motors. It is important to enable the diagnostic system to distinguish sensor drift and equipment failure. We have developed a sensor drift diagnostic method that combines some highly correlative sensor signals by using the MT (Mahalanobis-Taguchi) method. Furthermore, we have developed an equipment failure diagnostic method that measures the Mahalanobis distance from the normal state of equipment by the MT method. These methods can respectively detect sensor drift and equipment failure, but there are the following problems. In the sensor drift diagnosis, there is a possibility of misjudging the sensor drift when the equipment failure occurs and the process signal changes because the behavior of the process signal is the same as that of the sensor drift. Oppositely, in the equipment failure diagnosis, there is a possibility of misjudging the equipment failure when the sensor drift occurs because the sensor drift influences the change of process signal. To solve these problems, we propose a diagnostic method combining the sensor drift diagnosis and the equipment failure diagnosis by the MT method. Firstly, the sensor drift values are estimated by the sensor drift diagnosis, and the sensor drift is removed from the process signal. It is necessary to judge the validity of the estimated sensor drift values before removing the sensor drift from the process signal. We developed a method for judging the validity of the estimated sensor drift values by using the drift distribution based on the sensor calibration data. And then, the equipment failure is diagnosed by using the process signals after removal of the sensor drifts. To verify the developed diagnostic system, several sets of simulation data based on abnormal cases

  4. New interpretation of laser gyro drifts

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Discuss and develop some contents which are relevant to the IEEE Std 647TM-2006 in this paper. The IEEE Std only involves Allan variance, and decomposes it into five primary noise terms, in which, however, the noise nature of the so called "rate random walk noise" and the "rate ramp" is doubted by the IEEE Std editors. Here we use a mathematical identity to entirely affirm the first query and partially the second query as mentioned above. Besides, we argue that only the classical variance can be used in navigation, not the Allan variance. In order to seek the true nature of all drift terms in the variance, we adopt our original work that represents the noises as damped oscillations, to obtain the power spectral density (PSD) of the noises which is then transformed back into time domain. When the damped time constant is much longer than the sampling interval, the re-sulting slow variation term may be expanded into three terms: ordinary bias instability, rate random walk, and rate ramp. Therefore, these "noise terms" are not independent, and they are more of deterministic errors than random noises, and can be explained quantitatively. The resulting fast variation drift may be expanded into two terms. The first term is the same as angle random noise, while the second term adds to the true quantization noise term to form a new combined term called "quantiza-tion noise term". As the result of our research, not only the IEEE Std editors’ suspicions above are answered completely, but a new theory to analyze the laser gyro drifts is also presented, with several supporting examples to explain and verify the theory.

  5. Development of quadrupole focussing lenses for drift tube linac

    International Nuclear Information System (INIS)

    A linear accelerator comprising of Radio frequency quadruple (RFQ) and drift tube linac (DTL) is being developed by BARC. The alvarez type post-coupled cw DTL accelerates protons from an energy of 3 MeV to 20 MeV. The drift tube linac is excited in TM010 mode, wherein the particles are accelerated by longitudinal Electric fields at the gap crossings between drift tubes. The particles are subjected to transverse RF defocusing forces at the gap crossings due to the increasing electric fields in the gap. The transverse defocusing is corrected by housing magnetic quadrupole focussing lenses inside the drift tubes. The permanent magnet quadrupoles are placed inside the hermetically sealed drift tubes and provide constant magnetic field gradient in the beam aperture. The drift tubes are mounted concentrically inside the resonating DTL tank and are attached to the tank body with stems. Rare earth permanent magnets have been used to achieve the high field gradient. The drift tube body is subjected to RF heating due to eddy currents and hence the sealed drift tubes are to be cooled from inside. The temperature rise of the drift tube assemblies has to be limited to avoid demagnetization of permanent magnets and also to limit thermal expansion of the tubes. This paper discusses various aspects of magnetic design, selection of magnetic materials and the engineering development involved in the assembly of the drift tubes. (author)

  6. Daytime plasma drifts in the equatorial lower ionosphere

    Science.gov (United States)

    Hui, Debrup; Fejer, Bela G.

    2015-11-01

    We have used extensive radar measurements from the Jicamarca Observatory during low solar flux periods to study the quiet time variability and altitudinal dependence of equatorial daytime vertical and zonal plasma drifts. The daytime vertical drifts are upward and have largest values during September-October. The day-to-day variability of these drifts does not change with height between 150 and 600 km, but the bimonthly variability is much larger in the F region than below about 200 km. These drifts vary linearly with height generally increasing in the morning and decreasing in the afternoon. The zonal drifts are westward during the day and have largest values during July-October. The 150 km region zonal drifts have much larger day-to-day, but much smaller bimonthly variability than the F region drifts. The daytime zonal drifts strongly increase with height up to about 300 km from March through October, and more weakly at higher altitudes. The December solstice zonal drifts have generally weaker altitudinal dependence, except perhaps below 200 km. Current theoretical and general circulation models do not reproduce the observed altitudinal variation of the daytime equatorial zonal drifts.

  7. A drift formulation of Gresham's Law

    OpenAIRE

    Reginald D. Smith

    2012-01-01

    In this paper we analyze Gresham's Law, in particular, how the rate of inflow or outflow of currencies is affected by the demand elasticity of arbitrage and the difference in face value ratios inside and outside of a country under a bimetallic system. We find that these equations are very similar to those used to describe drift in systems of free charged particles. In addition, we look at how Gresham's Law would play out with multiple currencies and multiple countries under a variety of conne...

  8. Analysis of digisonde drift measurements quality

    Czech Academy of Sciences Publication Activity Database

    Kouba, Daniel; Koucká Knížová, Petra

    90-91, December (2012), s. 212-221. ISSN 1364-6826. [IAGA/ICMA/CAWSES-II TG4 Workshop on Vertical Coupling in the Atm osphere-Ionosphere System /4./. Prague, 14.02.2011-18.02.2011] R&D Projects: GA AV ČR KJB300420904; GA AV ČR IAA300420704 Institutional support: RVO:68378289 Keywords : Ionosphere * Plasma drifts * Skymap * Digisonde Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.417, year: 2012 http://www.sciencedirect.com/science/article/pii/S1364682612001290

  9. The Mark II Vertex Drift Chamber

    International Nuclear Information System (INIS)

    We have completed constructing and begun operating the Mark II Drift Chamber Vertex Detector. The chamber, based on a modified jet cell design, achieves 30 μm spatial resolution and 2 gas mixtures. Special emphasis has been placed on controlling systematic errors including the use of novel construction techniques which permit accurate wire placement. Chamber performance has been studied with cosmic ray tracks collected with the chamber located both inside and outside the Mark II. Results on spatial resolution, average pulse shape, and some properties of CO2 mixtures are presented. 10 refs., 12 figs., 1 tab

  10. DRIFT study of pitches and separated mesophase

    Energy Technology Data Exchange (ETDEWEB)

    Machnikowski, J.; Krzton, A.; Weber, J.V.; Zimny, T.; Petryniak, J.; Wiecek, I. [Technical University of Wroclaw, Wroclaw (Poland). Institute of Chemistry and Technology of Petroleum and Coal

    1995-12-31

    Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) was used to assess the structural changes associated with an early stage of carbonization in pitches of different origin, including coal tar, coal hydrogenation product and petroleum pitch. It was shown that an increase in aromaticity was rather slight in the case of coal tar pitch. It was confirmed that the chemical structure of the mesophase produced at an early stage of carbonization was controlled mostly by the nature of the parent pitch. 4 refs., 1 fig., 1 tab.

  11. Characteristics of the ALICE Silicon Drift Detector

    International Nuclear Information System (INIS)

    A Silicon Drift Detector (SDD) with an active area of 7.0x7.5 cm2 has been designed, produced and tested for the ALICE Inner Tracking System. The development of the SDD has been focused on the capability of the detector to work without an external support to the integrated high-voltage divider. Several features have been implemented in the design in order to increase the robustness and the long-term electrical stability of the detector. One of the prototypes has been tested in a pion beam at the CERN SPS. Preliminary results on the position resolution are given

  12. Drift Tube Linac Conditioning of Tank1

    CERN Document Server

    Shafqat, N; Toor, W A

    2014-01-01

    Tank1 of the Drift Tube Linac (DTL) of the Linac4 has been conditioned at the Linac4 tunnel. The tank was tuned for resonance at 352.2 MHz, and stable operation has been achieved with 725 µs long RF pulses at a repetition rate of 1 Hz. The maximum RF level that has been reached is 810 kW with a pulse width of 600 µs. Since this was the first RF structure exclusively conditioned in the Linac4 tunnel with the operation and control software of Linac4, some related issues and limitations had to be taken into account.

  13. Demersally drifting invertebrates from Kongsfjorden, Svalbård (Arctic Ocean)-a comparison of catches from drift-pump and drift-nets

    Science.gov (United States)

    Dahms, Hans-Uwe; Joo, Hyoung-Min; Lee, Jae Hyung; Yun, Mi Sun; Ahn, So Hyun; Lee, Sang Heon

    2015-12-01

    Demersally drifting organisms were collected at Ny Ålesund (Svalbård-Arctic Ocean) to study the taxon composition and relative abundances in the Arctic summer. Catch potentials of two collection devices for demersal drift were compared. A lowvolume submersible drift-pump and a drift-net unit were employed for the collection of demersally drifting biota, particularly for shallow aquatic habitats. With the exception of Appendicularia, Chaetognatha, Coelenterata, and Ctenophora, which were damaged at times, the pump catches were in good condition and sufficient for identification and quantification of less mobile fauna. A comparison of the two devices revealed that the drift-pump collected more specimens than the drift-net. However, the drift-net may have caused an underestimation of the abundances of invertebrates. No differences in identified taxon number and indices of richness, evenness and diversity were found. However, the proportion of invertebrate animals in the two devices was different for the three groups: zooplankton, macrofauna and meiofauna. At Svalbård, zooplankton, larvae of macrofauna, and meiofauna were successfully collected by the two collecting devices. However, the catchibility of the two devices in collecting various invertebrate taxa was different and, therefore, a sound `Device Effect' was revealed.

  14. Indoor spray measurement of spray drift potential using a spray drift test bench : effect of drift-reducing nozzle types, spray boom height, nozzle spacing and forward speed

    NARCIS (Netherlands)

    Moreno Ruiz, J.R.

    2014-01-01

    In a series of indoor experiments spray drift potential was assessed when spraying over a spray drift testbench with two different driving speeds, 2m/s and 4m/s, two different spray boom heights, 30 cm and 50 cm, and two different nozzle spacing, 25 cm and 50 cm, for six different nozzle types. The

  15. Double beta decay experiments

    OpenAIRE

    Barabash, A. S.

    2011-01-01

    The present status of double beta decay experiments is reviewed. The results of the most sensitive experiments are discussed. Proposals for future double beta decay experiments with a sensitivity to the $$ at the level of (0.01--0.1) eV are considered.

  16. Negative Beta Encoder

    CERN Document Server

    Kohda, Tohru; Aihara, Kazuyuki

    2008-01-01

    A new class of analog-digital (A/D), digital-analog (D/A) converters as an alternative to conventional ones, called $\\beta$-encoder, has been shown to have exponential accuracy in the bit rates while possessing self-correction property for fluctuations of amplifier factor $\\beta$ and quantizer threshold $\

  17. Betting against Beta

    DEFF Research Database (Denmark)

    Frazzini, Andrea; Heje Pedersen, Lasse

    2014-01-01

    We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for...

  18. The OML-SprayDrift model for predicting pesticide drift and deposition from ground boom sprayers

    DEFF Research Database (Denmark)

    Løfstrøm, Per; Bruus, Marianne; Andersen, Helle Vibeke;

    2013-01-01

    . The Gaussian tilting plume principle was applied inside the stayed track. The model was developed on one set of field experiments using a flat-fan nozzle and validated against another set of field experiments using an air-induction nozzle. The vertical spray-drift profile was measured using hair curlers...

  19. Field experiment on spray drift: Deposition and airborne drift during application to a winter wheat crop

    NARCIS (Netherlands)

    Wolters, A.; Linnemann, V.; Zande, van de J.C.; Vereecken, H.

    2008-01-01

    A field experiment was performed to evaluate various techniques for measuring spray deposition and airborne drift during spray application to a winter wheat crop. The application of a spraying agent containing the fluorescent dye Brilliant Sulfo Flavine by a conventional boom sprayer was done accord

  20. Rapid synthesis of beta zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  1. EMPLACEMENT DRIFT ISOLATION DOOR CONTROL SYSTEM

    International Nuclear Information System (INIS)

    The purpose of this analysis is to review and refine key design concepts related to the control system presently under consideration for remotely operating the emplacement drift isolation doors at the potential subsurface nuclear waste repository at Yucca Mountain. This analysis will discuss the key design concepts of the control system that may be utilized for remotely monitoring, opening, and closing the emplacement drift isolation doors. The scope and primary objectives of this analysis are to: (1) Discuss the purpose and function of the isolation doors (Presented in Section 7.1). (2) Review the construction of the isolation door and other physical characteristics of the doors that the control system will interface with (Presented in Section 7.2). (3) Discuss monitoring and controlling the operation of the isolation doors with a digital control system (either a Programmable Logic Controller (PLC) system or a Distributed Control System (DCS)) (Presented in Section 7.3). (4) Discuss how all isolation doors can be monitored and controlled from a subsurface central control center (Presented in Section 7.4). This analysis will focus on the development of input/output (I/O) counts including the types of I/O, redundancy and fault tolerance considerations, and processor requirements for the isolation door control system. Attention will be placed on operability, maintainability, and reliability issues for the system operating in the subsurface environment with exposure to high temperatures and radiation

  2. Metabolic drift in the aging brain.

    Science.gov (United States)

    Ivanisevic, Julijana; Stauch, Kelly L; Petrascheck, Michael; Benton, H Paul; Epstein, Adrian A; Fang, Mingliang; Gorantla, Santhi; Tran, Minerva; Hoang, Linh; Kurczy, Michael E; Boska, Michael D; Gendelman, Howard E; Fox, Howard S; Siuzdak, Gary

    2016-05-01

    Brain function is highly dependent upon controlled energy metabolism whose loss heralds cognitive impairments. This is particularly notable in the aged individuals and in age-related neurodegenerative diseases. However, how metabolic homeostasis is disrupted in the aging brain is still poorly understood. Here we performed global, metabolomic and proteomic analyses across different anatomical regions of mouse brain at different stages of its adult lifespan. Interestingly, while severe proteomic imbalance was absent, global-untargeted metabolomics revealed an energymetabolic drift or significant imbalance in core metabolite levels in aged mouse brains. Metabolic imbalance was characterized by compromised cellular energy status (NAD decline, increased AMP/ATP, purine/pyrimidine accumulation) and significantly altered oxidative phosphorylation and nucleotide biosynthesis and degradation. The central energy metabolic drift suggests a failure of the cellular machinery to restore metabostasis (metabolite homeostasis) in the aged brain and therefore an inability to respond properly to external stimuli, likely driving the alterations in signaling activity and thus in neuronal function and communication. PMID:27182841

  3. Drifting subpulses and inner acceleration regions in radio pulsars

    CERN Document Server

    Gil, J; Geppert, U; Geppert, Ulrich

    2003-01-01

    The classical vacuum gap model of Ruderman & Sutherland, in which spark-associated subbeams of subpulse emission circulate around the magnetic axis due to the EB drift, provides a natural and plausible physical mechanism of the subpulse drift phenomenon. Recent progress in the analysis of drifting subpulses in pulsars has provided a strong support to this model by revealing a number of subbeams circulating around the magnetic axis in a manner compatible with theoretical predictions. However, a more detailed analysis revealed that the circulation speed in a pure vacuum gap is too high when compared with observations. Moreover, some pulsars demonstrate significant time variations of the drift rate, including a change of the apparent drift direction, which is obviously inconsistent with the EB drift scenario in a pure vacuum gap. We resolved these discrepancies by considering a partial flow of iron ions from the positively charged polar cap, coexisting with the production of outflowing electron-positron plas...

  4. Ground Control for Non-Emplacement Drifts for LA

    International Nuclear Information System (INIS)

    The purpose of this calculation is to analyze the stability of repository non-emplacement drifts during the preclosure period, and to provide a final ground support method for non-emplacement drifts for the License Application (LA). This calculation will provide input for the development of LA documents. The scope of this calculation is limited to the non-emplacement drifts including access mains, ramps, exhaust mains, turnouts, intersections between access mains and turnouts, and intersections between exhaust mains and emplacement drifts, portals, TBM launch chambers, observation drift and test alcove in the performance confirmation (PC) facilities, etc. The calculation is limited to the non-emplacement drifts subjected to a combined loading of in-situ stress, seismic stress, and/or thermal stress. Other effects such as hydrological and chemical effects are not considered in this analysis

  5. Weak drifts of infinitely divisible distributions and their applications

    CERN Document Server

    Sato, Ken-iti

    2012-01-01

    Weak drift of an infinitely divisible distribution $\\mu$ on $\\mathbb{R}^d$ is defined by analogy with weak mean; properties and applications of weak drift are given. When $\\mu$ has no Gaussian part, the weak drift of $\\mu$ equals the minus of the weak mean of the inversion $\\mu'$ of $\\mu$. Applying the concepts of having weak drift 0 and of having weak drift 0 absolutely, the ranges, the absolute ranges, and the limit of the ranges of iterations are described for some stochastic integral mappings. For L\\'{e}vy processes the concepts of weak mean and weak drift are helpful in giving necessary and sufficient conditions for the weak law of large numbers and for the weak version of Shtatland's theorem on the behavior near $t=0$; those conditions are obtained from each other through inversion.

  6. In-Drift Precipitates/Salts Model

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2004-11-09

    This report documents the development and validation of the in-drift precipitates/salts (IDPS) model. The IDPS model is a geochemical model designed to predict the postclosure effects of evaporation and deliquescence on the chemical composition of water within the Engineered Barrier System (EBS) in support of the Total System Performance Assessment for the License Application (TSPA-LA). Application of the model in support of TSPA-LA is documented in ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2004 [DIRS 169860]). Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration (BSC 2004 [DIRS 171156]) is the technical work plan (TWP) for this report. It called for a revision of the previous version of the report (BSC 2004 [DIRS 167734]) to achieve greater transparency, readability, data traceability, and report integration. The intended use of the IDPS model is to estimate and tabulate, within an appropriate level of confidence, the effects of evaporation, deliquescence, and potential environmental conditions on the pH, ionic strength, and chemical compositions of water and minerals on the drip shield or other location within the drift during the postclosure period. Specifically, the intended use is as follows: (1) To estimate, within an appropriate level of confidence, the effects of evaporation and deliquescence on the presence and composition of water occurring within the repository during the postclosure period (i.e., effects on pH, ionic strength, deliquescence relative humidity, total concentrations of dissolved components in the system Na-K-H-Mg-Ca-Al-Cl-F-NO{sub 3}-SO{sub 4}-Br-CO{sub 3}-SiO{sub 2}-CO{sub 2}-O{sub 2}-H{sub 2}O, and concentrations of the following aqueous species that potentially affect acid neutralizing capacity: HCO{sub 3}{sup -}, CO{sub 3}{sup 2-}, OH{sup -}, H{sup +}, HSO{sub 4}{sup -}, Ca{sup 2+}, Mg{sup 2+}, CaHCO{sub 3}{sup +}, MgHCO{sub 3

  7. In-Drift Precipitates/Salts Model

    International Nuclear Information System (INIS)

    This report documents the development and validation of the in-drift precipitates/salts (IDPS) model. The IDPS model is a geochemical model designed to predict the postclosure effects of evaporation and deliquescence on the chemical composition of water within the Engineered Barrier System (EBS) in support of the Total System Performance Assessment for the License Application (TSPA-LA). Application of the model in support of TSPA-LA is documented in ''Engineered Barrier System: Physical and Chemical Environment Model'' (BSC 2004 [DIRS 169860]). Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration (BSC 2004 [DIRS 171156]) is the technical work plan (TWP) for this report. It called for a revision of the previous version of the report (BSC 2004 [DIRS 167734]) to achieve greater transparency, readability, data traceability, and report integration. The intended use of the IDPS model is to estimate and tabulate, within an appropriate level of confidence, the effects of evaporation, deliquescence, and potential environmental conditions on the pH, ionic strength, and chemical compositions of water and minerals on the drip shield or other location within the drift during the postclosure period. Specifically, the intended use is as follows: (1) To estimate, within an appropriate level of confidence, the effects of evaporation and deliquescence on the presence and composition of water occurring within the repository during the postclosure period (i.e., effects on pH, ionic strength, deliquescence relative humidity, total concentrations of dissolved components in the system Na-K-H-Mg-Ca-Al-Cl-F-NO3-SO4-Br-CO3-SiO2-CO2-O2-H2O, and concentrations of the following aqueous species that potentially affect acid neutralizing capacity: HCO3-, CO32-, OH-, H+, HSO4-, Ca2+, Mg2+, CaHCO3+, MgHCO3+, HSiO3-, and MgOH+); (2) To estimate, within an appropriate level of confidence, mineral precipitation resulting from the evaporation of

  8. Wave-induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    Directory of Open Access Journals (Sweden)

    M. Drivdal

    2014-12-01

    Full Text Available This study focuses on how wave–current and wave–turbulence interactions modify the transport of buoyant particles in the ocean. Here the particles can represent oil droplets, plastic particles, or plankton such as fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM, modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production, as well as the stronger veering by the Coriolis–Stokes force, affects the drift of the particles. The energy and momentum fluxes, as well as the Stokes drift, depend on the directional wave spectrum obtained from a wave model. As a first test, the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (i.e., classical Ekman theory. Secondly, the model is applied to a case in which we investigate the oil drift after an oil spill off the west coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by oil-drift models. In this case, using wind and wave forcing from the ERA Interim archive it is shown that the wave effects are important for the resultant drift and have the potential to improve drift forecasting.

  9. Climatology of F region zonalplasma drifts over Jicamarca

    OpenAIRE

    Fejer, Bela G.; J. R. Souza; Santos, A. S.; Costa Pereira, A. E.

    2005-01-01

    [1] We use extensive incoherent scatter radar observations made at the Jicamarca Radio Observatory between 1970 and 2003 to study and model empirically the equatorial zonal plasma drifts near the F region peak using Bernstein polynomials as base functions. Our quiet-time model results confirm that the daytime drifts are westward and are nearly season and solar cycle independent. The nighttime drifts are eastward, have larger magnitudes, and increase strongly with solar flux, particularly near...

  10. Drifting Abnormal Rolls in Electroconvection of Hybrid Aligned Nematic

    OpenAIRE

    Delev, V. A.; Krekhov, A. P.

    2001-01-01

    We report experimental and theoretical results on the conductive regime of electroconvection in hybrid aligned nematics. The drifting oblique/normal rolls below/above the Lifshitz frequency are observed at the onset of electroconvection under a.c. voltage. The experimental data on the threshold voltage, wavelength, oblique angle and drift period of the rolls as function of a.c. frequency are in good agreement with the results of linear stability analysis. The transition from drifting oblique ...

  11. Ionization wave propagation on a micro cavity plasma array

    Energy Technology Data Exchange (ETDEWEB)

    Wollny, Alexander; Hemke, Torben; Gebhardt, Markus; Peter Brinkmann, Ralf; Mussenbrock, Thomas [Institute of Theoretical Electrical Engineering, Ruhr University Bochum, D-44780 Bochum (Germany); Boettner, Henrik; Winter, Joerg; Schulz-von der Gathen, Volker [Institute for Experimental Physics II, Ruhr University Bochum, D-44780 Bochum (Germany); Xiong, Zhongmin; Kushner, Mark J. [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

    2011-10-03

    Microcavity plasma arrays of inverse pyramidal cavities fabricated on p-Si wafers act as localized dielectric barrier discharges. When operated at atmospheric pressure in argon and excited with high voltage at 10 kHz, a strong interaction between individual cavities is observed leading to wave-like optical emission propagating along the surface of the array. This phenomenon is numerically investigated. The computed ionization wave propagates with a speed of 5 km/s, which agrees well with experiments. The wave propagation is due to the sequential drift of electrons followed by drift of ions between cavities seeded by photoemission of electrons by the plasma in adjacent cavities.

  12. Stability of relativistic laminar flow equilibria for electrons drifting in crossed fields

    International Nuclear Information System (INIS)

    The stability of the electron flow in magnetically insulated transmission lines and diodes, and in microwave devices is an important issue. Presented in this paper are the results of an electromagnetic, linear stability analysis of transverse magnetic waves propagating along the direction of electron drift in a planar system described by a relativistic laminar flow equilibrium. In general, this equilibrium features cold electrons executing E x B drifts in self-consistently calculated electromagnetic fields. For this paper, a class of laminar flow equilibria in which the relativistic plasma and cyclotron frequencies are multiples of one another was chosen, and the electrons were taken to be confined to a layer placed in a vacuum gap between two conductors. This configuration is driven unstable by two separate mechanisms which tap the free energy associated with the sheared velocity field of the layer. At long wavelengths, the interaction of positive and negative energy surface waves results in the diocotron instability. At shorter wavelengths, the interaction of surface waves and sheets of electrons resonant at the local Doppler-shifted cyclotron frequencies leads to a pair of unstable branches of the dispersion relation which are referred to collectively as the magnetron instability. The scaling of the growth rates with equilibrium parameters and the relative importance of the two instabilities are discussed

  13. Full-field drift Hamiltonian particle orbits in 3D geometry

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, W A; Graves, J P; Brunner, S [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH1015 Lausanne (Switzerland); Isaev, M Yu, E-mail: wilfred.cooper@epfl.ch [Nuclear Fusion Institute, RRC ' Kurchatov Institute' , 123182 Moscow (Russian Federation)

    2011-02-15

    A Hamiltonian/Lagrangian theory to describe guiding centre orbit drift motion which is canonical in the Boozer coordinate frame has been extended to include full electromagnetic perturbed fields in anisotropic pressure 3D equilibria with nested magnetic flux surfaces. A redefinition of the guiding centre velocity to eliminate the motion due to finite equilibrium radial magnetic fields and the choice of a gauge condition that sets the radial component of the electromagnetic vector potential to zero are invoked to guarantee that the Boozer angular coordinates retain the canonical structure. The canonical momenta are identified and the guiding centre particle radial drift motion and parallel gyroradius evolution are derived. The particle coordinate position is linearly modified by wave-particle interactions. All the nonlinear wave-wave interactions appear explicitly only in the evolution of the parallel gyroradius. The radial variation of the electrostatic potential is related to the binormal component of the displacement vector for MHD-type perturbations. The electromagnetic vector potential projections can then be determined from the electrostatic potential and the radial component of the MHD displacement vector.

  14. THERMAL TEST ALCOVE HEATED DRIFT GROUND SUPPORT ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    S. Bonabian

    1996-10-03

    The main purpose and objective of this analysis is to analyze the stability of the Thermal Test Facility Heated Drift and to design a ground support system. The stability of the Heated Drift is analyzed considering in situ, seismic, and thermal loading conditions. A ground support system is recommended to provide a stable opening for the Heated Drift. This report summarizes the results of the analyses and provides the details of the recommended ground support system for the Heated Drift. The details of the ground support system are then incorporated into the design output documents for implementation in the field.

  15. HF doppler sounder measurements of the ionospheric signatures of small scale ULF waves

    Science.gov (United States)

    Baddeley, L. J.; Yeoman, T. K.; Wright, D. M.

    2005-07-01

    An HF Doppler sounder, DOPE (DOppler Pulsation Experiment) with three azimuthally-separated propagation paths is used to provide the first statistical examination of small scale-sized, high m waves where a direct measurement of the azimuthal wavenumber m, is made in the ionosphere. The study presents 27 events, predominantly in the post-noon sector. The majority of events are Pc4 waves with azimuthal m numbers ranging from 100 to 200, representing some of the smallest scale waves ever observed in the ionosphere. 4 Pc5 waves are observed in the post-noon sector. The fact that measurements for the wave azimuthal m number and the wave angular frequency are available allows the drift-bounce resonance condition to be used to hypothesise potential particle populations which could drive the waves through either a drift or drift-bounce resonance interaction mechanism. These results are compared with the statistical study presented by Baddeley et al. (2004) which investigated the statistical likelihood of such driving particle populations occurring in the magnetospheric ring current. The combination of these two studies indicates that any wave which requires a possible drift resonance interaction with particles of energies >60 keV, is statistically unlikely to be generated by such a mechanism. The evidence presented in this paper therefore suggests that in the pre-noon sector the drift-bounce resonance mechanism is statistically more likely implying an anti-symmetric standing wave structure while in the post-noon sector both a drift or drift-bounce resonance interaction is statistically possible, indicating both symmetric and anti-symmetric standing mode structures. A case study is also presented investigating simultaneous observations of a ULF wave in ground magnetometer and DOPE data. The event is in the lower m range of the statistical study and displays giant pulsation (Pg) characteristics. Keywords. Ionosphere (Ionosphere-magnetosphere interactions) Magnetospheric

  16. Production of Magnetic Turbulence by Cosmic Rays Drifting Upstream of Supernova Remnant Shocks

    Science.gov (United States)

    Stroman, Thomas; Niemiec, Jacek; Pohl, Martin; Nishikawa, Ken-ichi

    2008-01-01

    I will present results of our recent two- and three-dimensional Particle-In-Cell simulations of magnetic-turbulence production by cosmic-ray ions drifting upstream of supernova remnant shocks. These studies' aim is twofold: test recent predictions of strong amplification in short wavelength, non-resonant wave modes, and study the subsequent evolution of the magnetic turbulence, including its backreaction on cosmic-ray trajectories. We confirm that the drifting cosmic rays give rise to a turbulent magnetic field, but show that an oblique filamentary mode grows more rapidly than the non-resonant parallel modes found in analytical theory. The field perturbations grow more slowly than estimated using a quasi-linear analytical approach for the parallel plane-wave mode, and saturate in amplitude at deltaB/B approximately equal to 1. The backreaction of the magnetic turbulence on the particles leads to an alignment of the bulk-flow velocities of the cosmic rays and the background medium. This is an essential characteristic of cosmic ray-modified shocks: the upstream flow speed is continuously changed by the cosmic rays. The reduction of relative drift between cosmic rays and background medium accounts for the saturation of the instability at only moderate magnetic-field amplitudes. It is possible that the prolonged magnetic field growth observed in recent MHD simulations results from a cosmic-ray current assumed to be constant and thus immune to the backreaction from the turbulent field. We speculate that the parallel plane-wave mode found in analytical treatments very quickly leads co filamentation, which we observe in our PIC modeling and is also apparent in the MHD simulations.

  17. Flashing coupled density wave oscillation

    International Nuclear Information System (INIS)

    The experiment was performed on the test loop (HRTL-5), which simulates the geometry and system design of the 5 MW reactor. The phenomenon and mechanism of different kinds of two-phase flow instabilities, namely geyser instability, flashing instability and flashing coupled density wave instability are described. The especially interpreted flashing coupled density wave instability has never been studied well, it is analyzed by using a one-dimensional non-thermo equilibrium two-phase flow drift model computer code. Calculations are in good agreement with the experiment results. (5 refs.,5 figs., 1 tab.)

  18. THE DIAGNOSTIC VALUE OF PULSED WAVE TISSUE DOPPLER IMAGING IN ASYMPTOMATIC BETA- THALASSEMIA MAJOR CHILDREN AND YOUNG ADULTS ; RELATION TO CHEMICAL BIOMARKERS OF LEFT VENTRICULAR FUNCTION AND IRON OVERLOAD .

    Directory of Open Access Journals (Sweden)

    Seham Ragab

    2015-08-01

    Full Text Available Background: Cardiac iron toxicity is the leading cause of death among  β-halassaemia major (TM  patients.  Once  heart failure becomes overt , it will be  difficult to reverse . Objectives: To investigate non overt cardiac dysfunctions  in TM patients using  pulsed wave Tissue Doppler  Imaging (TD I and its relation to the iron overload and brain natruritic peptide (BNP. Methods: Thorough  clinical , conventional echo and  pulsed  wave TDI  parameters were compared between  asymtomatic 25 β-TM  patients  and 20 age and gender matched individuals. Serum ferritin and plasma BNP  levels were assayed by  ELISA .  Results: TM patients had significant higher mitral inflow early diastolic (E wave and  non significant other conventional echo  parameters. Pulsed wave TDI revealed systolic and diastolic dysfunctions in the form of significant higher  isovolumetric contraction time (ICT , ejection time ( E T and  isovolumetric relaxation time (IRT with significantly lower  mitral annulus  early diastolic velocity E` (12.07 ±2.06 vs 15.04±2.65 ,P= 0.003  in patients compared to  controls. Plasma BNP was higher in patients compared to the controls.  Plasma BNP and serum ferritin had significant correlation with each other and with pulsed wave conventional and TDI indices of systolic and diastolic functions.  Patients with E/E` ≥ 8 had  significant higher  serum ferritin  and plasma BNP levels compared to those with E/E` ratio < 8 without difference in Hb levels .Conclusion:  Pulsed wave TDI  is an  important diagnostic tool for latent cardiac dysfunction in iron loaded TM patients and is related to iron overload and BNP .

  19. Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR

    International Nuclear Information System (INIS)

    The objective of this calculation is to provide in-drift physical properties required by the drift-scale models (both two- and three-dimensional) used in total system performance assessments (TSPA). The physical properties include waste package geometry, waste package thermal properties, emplacement drift geometry including backfill and invert geometry and properties (both thermal and hydrologic), drip shield geometry and thermal properties, all tabulated in a single source

  20. Measurements of electron drift and diffusion properties in a large cylindrical drift chamber (TPC) with parallel electric and magnetic fields

    International Nuclear Information System (INIS)

    This work describes measurements on the drift of electrons in gases, using the TPC90, the prototype of the ALEPH Time Projection Chamber. Tracks which were created by UV-Laser ionization have been drifted over distances of up to 1.3 m in parallel electric and magnetic fields. Electron drift properties have been systematically measured as a function of these, in several gas mixtures. (orig./HSI)