Electromagnetic resonance waves
International Nuclear Information System (INIS)
Villaba, J.M.; Manjon, F.J.; Guirao, A.; Andres, M.V.
1994-01-01
We describe in this paper a set of experiments designed to make qualitative and quantitative measurements on electromagnetic resonances of several simple systems. The experiments are designed for the undergraduate laboratory of Electricity and Magnetism in Physics. These experiments can help the students understanding the concept of resonance, which appears in different fields of Physics. (Author) 8 refs
Three-Dimensional Electromagnetic High Frequency Axisymmetric Cavity Scars.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Jorgenson, Roy Eberhardt
2014-10-01
This report examines the localization of high frequency electromagnetic fi elds in three-dimensional axisymmetric cavities along periodic paths between opposing sides of the cavity. The cases where these orbits lead to unstable localized modes are known as scars. This report treats both the case where the opposing sides, or mirrors, are convex, where there are no interior foci, and the case where they are concave, leading to interior foci. The scalar problem is treated fi rst but the approximations required to treat the vector fi eld components are also examined. Particular att ention is focused on the normalization through the electromagnetic energy theorem. Both projections of the fi eld along the scarred orbit as well as point statistics are examined. Statistical comparisons are m ade with a numerical calculation of the scars run with an axisymmetric simulation. This axisymmetric cas eformstheoppositeextreme(wherethetwomirror radii at each end of the ray orbit are equal) from the two -dimensional solution examined previously (where one mirror radius is vastly di ff erent from the other). The enhancement of the fi eldontheorbitaxiscanbe larger here than in the two-dimensional case. Intentionally Left Blank
Nonlinear electromagnetic gyrokinetic equations for rotating axisymmetric plasmas
International Nuclear Information System (INIS)
Artun, M.; Tang, W.M.
1994-03-01
The influence of sheared equilibrium flows on the confinement properties of tokamak plasmas is a topic of much current interest. A proper theoretical foundation for the systematic kinetic analysis of this important problem has been provided here by presented the derivation of a set of nonlinear electromagnetic gyrokinetic equations applicable to low frequency microinstabilities in a rotating axisymmetric plasma. The subsonic rotation velocity considered is in the direction of symmetry with the angular rotation frequency being a function of the equilibrium magnetic flux surface. In accordance with experimental observations, the rotation profile is chosen to scale with the ion temperature. The results obtained represent the shear flow generalization of the earlier analysis by Frieman and Chen where such flows were not taken into account. In order to make it readily applicable to gyrokinetic particle simulations, this set of equations is cast in a phase-space-conserving continuity equation form
Resonant oscillations in open axisymmetric tubes
Amundsen, D. E.; Mortell, M. P.; Seymour, B. R.
2017-12-01
We study the behaviour of the isentropic flow of a gas in both a straight tube of constant cross section and a cone, open at one end and forced at or near resonance at the other. A continuous transition between these configurations is provided through the introduction of a geometric parameter k associated with the opening angle of the cone where the tube corresponds to k=0. The primary objective is to find long-time resonant and near-resonant approximate solutions for the open tube, i.e. k→ 0. Detailed analysis for both the tube and cone in the limit of small forcing (O(ɛ 3)) is carried out, where ɛ 3 is the Mach number of the forcing function and the resulting flow has Mach number O(ɛ ). The resulting approximate solutions are compared with full numerical simulations. Interesting distinctions between the cone and the tube emerge. Depending on the damping and detuning, the responses for the tube are continuous and of O(ɛ ). In the case of the cone, the resonant response involves an amplification of the fundamental resonant mode, usually called the dominant first-mode approximation. However, higher modes must be included for the tube to account for the nonlinear generation of higher-order resonances. Bridging these distinct solution behaviours is a transition layer of O(ɛ 2) in k. It is found that an appropriately truncated set of modes provides the requisite modal approximation, again comparing well to numerical simulations.
RESONANT ABSORPTION OF AXISYMMETRIC MODES IN TWISTED MAGNETIC FLUX TUBES
Energy Technology Data Exchange (ETDEWEB)
Giagkiozis, I.; Verth, G. [Solar Plasma Physics Research Centre, School of Mathematics and Statistics, University of Sheffield, Hounsfield Road, Hicks Building, Sheffield, S3 7RH (United Kingdom); Goossens, M.; Doorsselaere, T. Van [Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Fedun, V. [Department of Automatic Control and Systems Engineering, University of Sheffield, Mappin Street, Amy Johnson Building, Sheffield, S1 3JD (United Kingdom)
2016-06-01
It has been shown recently that magnetic twist and axisymmetric MHD modes are ubiquitous in the solar atmosphere, and therefore the study of resonant absorption for these modes has become a pressing issue because it can have important consequences for heating magnetic flux tubes in the solar atmosphere and the observed damping. In this investigation, for the first time, we calculate the damping rate for axisymmetric MHD waves in weakly twisted magnetic flux tubes. Our aim is to investigate the impact of resonant damping of these modes for solar atmospheric conditions. This analytical study is based on an idealized configuration of a straight magnetic flux tube with a weak magnetic twist inside as well as outside the tube. By implementing the conservation laws derived by Sakurai et al. and the analytic solutions for weakly twisted flux tubes obtained recently by Giagkiozis et al. we derive a dispersion relation for resonantly damped axisymmetric modes in the spectrum of the Alfvén continuum. We also obtain an insightful analytical expression for the damping rate in the long wavelength limit. Furthermore, it is shown that both the longitudinal magnetic field and the density, which are allowed to vary continuously in the inhomogeneous layer, have a significant impact on the damping time. Given the conditions in the solar atmosphere, resonantly damped axisymmetric modes are highly likely to be ubiquitous and play an important role in energy dissipation. We also suggest that, given the character of these waves, it is likely that they have already been observed in the guise of Alfvén waves.
Resonant Electromagnetic Shunt Damping of Flexible Structures
DEFF Research Database (Denmark)
Høgsberg, Jan Becker
2016-01-01
Electromagnetic transducers convert mechanical energy to electrical energy and vice versa. Effective passive vibration damping of flexible structures can therefore be introduced by shunting with an accurately calibrated resonant electrical network thatcontains a capacitor to create the desired...
Electromagnetic resonance waves. Resonancias de ondas electromagneticas
Energy Technology Data Exchange (ETDEWEB)
Villaba, J.M.; Manjon, F.J.; Guirao, A.; Andres, M.V.
1994-01-01
We describe in this paper a set of experiments designed to make qualitative and quantitative measurements on electromagnetic resonances of several simple systems. The experiments are designed for the undergraduate laboratory of Electricity and Magnetism in Physics. These experiments can help the students understanding the concept of resonance, which appears in different fields of Physics. (Author) 8 refs.
International Nuclear Information System (INIS)
Nelson, E.M.
1993-12-01
Some two-dimensional finite element electromagnetic field solvers are described and tested. For TE and TM modes in homogeneous cylindrical waveguides and monopole modes in homogeneous axisymmetric structures, the solvers find approximate solutions to a weak formulation of the wave equation. Second-order isoparametric lagrangian triangular elements represent the field. For multipole modes in axisymmetric structures, the solver finds approximate solutions to a weak form of the curl-curl formulation of Maxwell's equations. Second-order triangular edge elements represent the radial (ρ) and axial (z) components of the field, while a second-order lagrangian basis represents the azimuthal (φ) component of the field weighted by the radius ρ. A reduced set of basis functions is employed for elements touching the axis. With this basis the spurious modes of the curl-curl formulation have zero frequency, so spurious modes are easily distinguished from non-static physical modes. Tests on an annular ring, a pillbox and a sphere indicate the solutions converge rapidly as the mesh is refined. Computed eigenvalues with relative errors of less than a few parts per million are obtained. Boundary conditions for symmetric, periodic and symmetric-periodic structures are discussed and included in the field solver. Boundary conditions for structures with inversion symmetry are also discussed. Special corner elements are described and employed to improve the accuracy of cylindrical waveguide and monopole modes with singular fields at sharp corners. The field solver is applied to three problems: (1) cross-field amplifier slow-wave circuits, (2) a detuned disk-loaded waveguide linear accelerator structure and (3) a 90 degrees overmoded waveguide bend. The detuned accelerator structure is a critical application of this high accuracy field solver. To maintain low long-range wakefields, tight design and manufacturing tolerances are required
Subwavelength resonant antennas enhancing electromagnetic energy harvesting
Oumbe Tekam, Gabin; Ginis, Vincent; Seetharamdoo, Divitha; Danckaert, Jan
2016-04-01
In this work, an electromagnetic energy harvester operating at microwave frequencies is designed based on a cut- wire metasurface. This metamaterial is known to contain a quasistatic electric dipole resonator leading to a strong resonant electric response when illuminated by electromagnetic fields.1 Starting from an equivalent electrical circuit, we analytically design the parameters of the system to tune the resonance frequency of the harvester at the desired frequency band. Subsequently, we compare these results with numerical simulations, which have been obtained using finite elements numerical simulations. Finally, we optimize the design by investigating the best arrangement for energy harvesting by coupling in parallel and in series many single layers of cut-wire metasurfaces. We also discuss the implementation of different geometries and sizes of the cut-wire metasurface for achieving different center frequencies and bandwidths.
Electromagnetic decay of giant resonances
International Nuclear Information System (INIS)
Beene, J.R.; Bertrand, F.E.; Halbert, M.L.; Auble, R.L.; Hensley, D.C.; Horen, D.J.; Robinson, R.L.; Sayer, R.O.; Sjoreen, T.P.
1985-01-01
Coincidence experiments were done to investigate the photon and neutron emission from the giant resonance regions of 208 Pb and 90 Zr using the ORNL Spin Spectrometer, a 72-segment NaI detector system. We have determined the total gamma-decay probability, the ground-state gamma branching ratio, and the branching ratios to a number of low-lying states as a function of excitation energy in 208 Pb to approx.15 MeV. Similar data were also obtained on 90 Zr. The total yield of ground-state E2 gamma radiation in 208 Pb and the comparative absence of such radiation in 90 Zr can only be understood if decay of compound (damped) states is considered. Other observations in 208 Pb include the absence of a significant branch from the giant quadrupole resonance (GQR) to the 3 - state at 2.6 MeV, a strong branch to a 3 - state at 4.97 MeV from the same region, and transitions to various 1 - states between 5 to 7 MeV from the E* approx. 14 MeV region (EO resonance)
Electromagnetic decay of giant resonances
International Nuclear Information System (INIS)
Beene, J.R.; Bertrand, F.E.; Halbert, M.L.; Auble, R.L.; Hensley, D.C.; Horen, D.J.; Robinson, R.L.; Sayer, R.O.; Sjoreen, T.P.
1985-01-01
Coincidence experiments are carried out to investigate the photon and neutron emission from the giant resonance regions of 208 Pb and 90 Zr using the ORNL Spin Spectrometer, a 72-segment NaI detector system. The authors determined the total gamma-decay probability, the ground-state gamma branching ratio, and the branching ratios to a number of low-lying states as a function of excitation energy in 208 Pb to ∼15 MeV. Similar data were also obtained on 90 Zr. The total yield of ground-state E2 gamma radiation in 208 Pb and the comparative absence of such radiation in 90 Zr can only be understood if decay of compound (damped) states is considered. (Auth.)
Resonance contribution to electromagnetic structure functions
International Nuclear Information System (INIS)
Bowling, A.L. Jr.
1974-01-01
The part of the pion and proton electromagnetic structure functions due to direct channel resonances in the virtual Compton amplitude is discussed. After a phenomenological discussion, based on the work of Bloom and Gilman, of resonance production in inelastic electroproduction, the single resonance contribution to the pion and proton structure functions is expressed in terms of transition form factors. Froissart-Gribov representations of the Compton amplitude partial waves are presented and are used to specify the spin dependence of the transition form factors. The dependence of the form factors on momentum transfer and resonance mass is assumed on the basis of the behavior of exclusive resonance electroproduction. The single resonance contributions are summed in the Bjorken limit, and the result exhibits Bjorken scaling. Transverse photons are found to dominate in the Bjorken limit, and the threshold behavior of the resonant part of the structure functions is related to the asymptotic behavior of exclusive form factors at large momentum transfer. The resonant parts of the annihilation structure functions are not in general given by simple analytic continuation in the scaling vari []ble ω' of the electroproduction structure functions. (Diss. Abstr. Int., B)
International Nuclear Information System (INIS)
Katanuma, I.; Kiwamoto, Y.; Adachi, S.; Inutake, M.; Ishii, K.; Yatsu, K.; Sawada, K.; Miyoshi, S.
1987-05-01
Calculations are made for neoclassical resonant-plateau transports in the geometry of the effectively axisymmetrized tandem mirror GAMMA 10 magnetic field, which has minimum B inbord anchors inside the axisymmetric plug/barrier mirror cells. Azimuthal drifts at the local non-axisymmetric regions are included. The radial potential profile is determined by solving selfconsistently the charge neutrality equation. A finite resistance connecting end plate to machine ground provides appropriate boundary conditions on the radial electrostatic potential distribution so that it can be determined uniquely. The calculation is consistent with experimental results of GAMMA 10. (author)
Penetrating power of resonant electromagnetic induction imaging
Directory of Open Access Journals (Sweden)
Roberta Guilizzoni
2016-09-01
Full Text Available The possibility of revealing the presence and identifying the nature of conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are shielded by external materials and thus cannot be directly accessed. Hence, interrogation techniques are required that allow penetration through the shielding materials, in order for the target to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. In this work, we demonstrate the power of resonant electromagnetic induction imaging to penetrate through metallic shields (1.5-mm-thick and image targets (having conductivities σ ranging from 0.54 to 59.77 MSm−1 concealed behind them.
Sridhar, S.; Touma, Jihad R.
2017-02-01
We study the resonant relaxation (RR) of an axisymmetric, low-mass (or Keplerian) stellar disc orbiting a more massive black hole (MBH). Our recent work on the general kinetic theory of RR is simplified in the standard manner by the neglect of 'gravitational polarization' and applied to a razor-thin axisymmetric disc. The wake of a stellar orbit is expressed in terms of the angular momenta exchanged with other orbits, and used to derive a kinetic equation for RR under the combined actions of self-gravity, 1 PN and 1.5 PN general relativistic effects of the MBH and an arbitrary external axisymmetric potential. This is a Fokker-Planck equation for the stellar distribution function (DF), wherein the diffusion coefficients are given self-consistently in terms of contributions from apsidal resonances between pairs of stellar orbits. The physical kinetics is studied for the two main cases of interest. (1) 'Lossless' discs in which the MBH is not a sink of stars, and disc mass, angular momentum and energy are conserved: we prove that general H-functions can increase or decrease during RR, but the Boltzmann entropy is (essentially) unique in being a non-decreasing function of time. Therefore, secular thermal equilibria are maximum entropy states, with DFs of the Boltzmann form; the two-ring correlation function at equilibrium is computed. (2) Discs that lose stars to the MBH through an 'empty loss cone': we derive expressions for the MBH feeding rates of mass, angular momentum and energy in terms of the diffusive fluxes at the loss-cone boundaries.
Absorption of acoustic waves by sunspots. II - Resonance absorption in axisymmetric fibril models
Rosenthal, C. S.
1992-01-01
Analytical calculations of acoustic waves scattered by sunspots which concentrate on the absorption at the magnetohydrodynamic Alfven resonance are extended to the case of a flux-tube embedded in a uniform atmosphere. The model is based on a flux-tubes of varying radius that are highly structured, translationally invariant, and axisymmetric. The absorbed fractional energy is determined for different flux-densities and subphotospheric locations with attention given to the effects of twist. When the flux is highly concentrated into annuli efficient absorption is possible even when the mean magnetic flux density is low. The model demonstrates low absorption at low azimuthal orders even in the presence of twist which generally increases the range of wave numbers over which efficient absorption can occur. Resonance absorption is concluded to be an efficient mechanism in monolithic sunspots, fibril sunspots, and plage fields.
Finite element analysis of the axisymmetric electromagnetic oscillations in the PHERMEX machine
International Nuclear Information System (INIS)
Fugelso, E.; Cook, W.A.
1977-01-01
The calculation of the electromagnetic field, characteristic frequency, and loss factors for the TM 010 mode of operation of the PHERMEX machine, a three-cavity, linear electron accelerator, were carried out using the finite element method. Perturbations from the simple, closed cylindrical shape cause changes in the electromagnetic field distribution and in the fundamental frequency, which will affect the electron-beam dynamics and the energy transfer to the beam. Cavity loss factors are essentially unaltered
Absorption of resonant electromagnetic radiation in electron-atom collisions
International Nuclear Information System (INIS)
Arslanbekov, T.U.; Pazdzerskii, V.A.; Usachenko, V.I.
1986-01-01
Nonrelativistic quantum theory is used to study the possibility of amplification of electromagnetic radiation in forced braking scattering of an electron beam on atoms. The interaction of the atom with the electromagnetic field is considered in the resonant approximation. Cases of large and small detuning from resonance are considered. It is shown that for any orientation of the electron beam relative to the field polarization vector, absorption of radiation occurs, with the major contribution being produced by atomic electrons
International Nuclear Information System (INIS)
Izotov, I. V.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G.; Bagryansky, P. A.; Beklemishev, A. D.; Prikhodko, V. V.
2012-01-01
Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap (''vortex'' confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of ''vortex'' confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.
Izotov, I V; Razin, S V; Sidorov, A V; Skalyga, V A; Zorin, V G; Bagryansky, P A; Beklemishev, A D; Prikhodko, V V
2012-02-01
Influence of shear flows of the dense plasma created under conditions of the electron cyclotron resonance (ECR) gas breakdown on the plasma confinement in the axisymmetric mirror trap ("vortex" confinement) was studied experimentally and theoretically. A limiter with bias potential was set inside the mirror trap for plasma rotation. The limiter construction and the optimal value of the potential were chosen according to the results of the preliminary theoretical analysis. This method of "vortex" confinement realization in an axisymmetric mirror trap for non-equilibrium heavy-ion plasmas seems to be promising for creation of ECR multicharged ion sources with high magnetic fields, more than 1 T.
Mounet, N
2009-01-01
This paper aims at giving an as complete and detailed as possible derivation of the six electromagnetic field components created by an offset point charge travelling at any speed in an infinitely long circular multilayer beam pipe. Outcomes from this study are a novel and efficient matrix method for the field matching determination of all the constants involved in the field components, and the generalization to any azimuthal mode together with the final summation on all such modes in the impedance formulas. In particular the multimode direct space-charge impedances (both longitudinal and transverse) are given, as well as the wall impedance to any order of precision. New quadrupolar terms for the transverse wall impedance are found, which look negligible in the ultrarelativistic case but might be of significance for low-energy beams. In principle from this analysis the electromagnetic fields created by any particular source, with a finite transverse shape, can then be computed using convolutions.
Breathers in Josephson junction ladders: Resonances and electromagnetic wave spectroscopy
DEFF Research Database (Denmark)
Miroshnichenko, A. E.; Flach, S.; Fistul, M.
2001-01-01
We present a theoretical study of the resonant interaction between dynamical localized states (discrete breathers) and linear electromagnetic excitations (EE's) in Josephson junction ladders. By making use of direct numerical simulations we find that such an interaction manifests itself by resonant...
Photoproduction of axions in a resonant electromagnetic cavity
International Nuclear Information System (INIS)
Dang Van Soa; Hoang Ngoc Long; Ha Huy Bang; Nguyen Mai Hung
2000-09-01
Photon-axion conversions in a resonant electromagnetic cavity with frequency equal to the axion mass are considered in detail by the Feynman diagram methods. The differential cross sections are presented and numerical evaluations are given. It is shown that there is a resonant conversion for the considered process. From our results, some estimates for experimental conditions are given. (author)
Mounet, Nicolas Frank; CERN. Geneva. ATS Department
2015-01-01
This note provides general and approximate formulas for the electromagnetic fields created by a passing beam in an axisymmetric infinitely thick resistive pipe made of a single homogeneous layer. The full derivations and their resulting approximate expressions at low and intermediate frequencies are given here, as well as the conditions under which those approximations are valid. Beam-coupling impedances are also computed, and examples are shown.
Electromagnetic excitation of the two-phonon giant dipole resonance
International Nuclear Information System (INIS)
Emling, H.
1994-03-01
It is the aim of this article to summarize our present knowledge on the double isovector giant dipole resonance (DGDR) and our understanding of the electromagnetic excitation mechanism in heavy ion collisions in the relativistic energy regime. In the following chapter, a brief resume on the history of giant resonances is given and, based on their understanding, conclusions on the expected properties of multi-phonon resonances are drawn. In chapter 2, the essential features of electromagnetic heavy ion interactions at (near) relativistic velocities will be illuminated and the theoretical framework is presented, which describes such processes. New experimental methods were required for an appropriate study of Coulomb dissociation processes, which are discussed in chapter 3 together with the experimental results. Chapter 4 is dedicated to summarize the results from electromagnetic excitation studies, to compare with those from alternative methods and, in particular, to contrast experimental findings with theoretical predictions and to address open problems. (orig.)
Electromagnetic resonance in the asymmetric terahertz metamaterials with triangle microstructure
Xing, Yuanyuan; Zhang, Xiaoyu; Zhang, Qiang; Gu, Yanping; Qian, Yunan; Lin, Xingyue; Tang, Yunhai; Cheng, Xinli; Qin, Changfa; Shen, Jiaoyan; Zang, Taocheng; Ma, Chunlan
2018-05-01
We investigate terahertz transmission properties and electromagnetic resonance modes in the asymmetric triangle structures with the change of asymmetric distance and the direction of electric field. When the THz electric field is perpendicular to the split gap of triangle, the electric field can better excite the THz absorption in the triangle structures. Importantly, electromagnetically induced transparency (EIT) characteristics are observed in the triangle structures due to the destructive interference of the different excited modes. The distributions of electric field and surface current density simulated by finite difference time domain indicate that the bright mode is excited by the side of triangle structures and dark mode is excited by the gap-side of triangle. The present study is helpful to understand the electromagnetic resonance in the asymmetric triangular metamaterials.
Static electromagnetic properties of giant resonances
International Nuclear Information System (INIS)
Koo, W.K.
1986-03-01
Static electric monopole and quadrupole matrix elements, which are related to the mean square radius and quadrupole moment respectively, are derived for giant resonances of arbitrary multipolarity. The results furnish information on the size and shape of the nucleus in the excited giant states. (author)
Nucleon resonance production in electromagnetic interactions
International Nuclear Information System (INIS)
Mukhtarov, A.I.; Sadykhov, F.S.; Vasil'ev, O.A.; Abdullaev, S.K.; Mustafaev, V.Z.
1977-01-01
The results of investigation into nucleon resonance production (NR) in the ep → eNsup(*)(eNsup(*)γ) and eantie → antipNsup(*)(antipNsup(*)γ) processes, where Nsup(*) is a nucleon resonance of the 3/2 or 5/2 spin are presented. The calculation of the NR structure functions with the mass M and 3/2 or 5/2 spin is carried out. The Δ(1236), N(1688) and Δ(2160) NR production was observed in the ep → eNsup(*) and eantie → antipNsup(*) processes. For the ep-interaction the energy dependence of the NR production differential cross section at the electron scattering angle THETA = 6 dea and the angular dependence of the longitudinal polarization degree of the scattered electrons at the electron energy of 6 GeV are presented. The energy dependence of the total cross section of the NR production for eantie → antipNsup(*) is obtained. The ep → eNsup(*)γ radiative electron scattering on a proton is investigated only in case of the Δ(1236)NR production. The dependence of the effective cross section of the Δ(1236) radiative production process on THETA for the energies of an incident and scattered electron of 6 and 2.5 GeV, respectively, and the dependence of the cross section on the scattered electron energy at the initial energy of 6 GeV and THETA = 15 deg are presented
Behavioral and Biological Effects of Resonant Electromagnetic Absorption in Rats.
1976-11-01
for 23-550 MHz, biological phantom materials to simulate tissue properties, monopole -above-ground radiation chamber, design of a waveguide slot array...Resonant Electromagnetic Power Absorption in Rats" L T OF FTCTIF S A,’L i .LIS SFigure Pa 1 A photograiph of the monopole -above-gruund radiation...and mice without ground effects (L/2b = 3.25 where 21Tb is the "average" circumference of the animals) ........ .................... ... 20 8
Na, Dong-Yeop; Omelchenko, Yuri A.; Moon, Haksu; Borges, Ben-Hur V.; Teixeira, Fernando L.
2017-10-01
We present a charge-conservative electromagnetic particle-in-cell (EM-PIC) algorithm optimized for the analysis of vacuum electronic devices (VEDs) with cylindrical symmetry (axisymmetry). We exploit the axisymmetry present in the device geometry, fields, and sources to reduce the dimensionality of the problem from 3D to 2D. Further, we employ 'transformation optics' principles to map the original problem in polar coordinates with metric tensor diag (1 ,ρ2 , 1) to an equivalent problem on a Cartesian metric tensor diag (1 , 1 , 1) with an effective (artificial) inhomogeneous medium introduced. The resulting problem in the meridian (ρz) plane is discretized using an unstructured 2D mesh considering TEϕ-polarized fields. Electromagnetic field and source (node-based charges and edge-based currents) variables are expressed as differential forms of various degrees, and discretized using Whitney forms. Using leapfrog time integration, we obtain a mixed E - B finite-element time-domain scheme for the full-discrete Maxwell's equations. We achieve a local and explicit time update for the field equations by employing the sparse approximate inverse (SPAI) algorithm. Interpolating field values to particles' positions for solving Newton-Lorentz equations of motion is also done via Whitney forms. Particles are advanced using the Boris algorithm with relativistic correction. A recently introduced charge-conserving scatter scheme tailored for 2D unstructured grids is used in the scatter step. The algorithm is validated considering cylindrical cavity and space-charge-limited cylindrical diode problems. We use the algorithm to investigate the physical performance of VEDs designed to harness particle bunching effects arising from the coherent (resonance) Cerenkov electron beam interactions within micro-machined slow wave structures.
Resonant scattering in the presence of an electromagnetic field
International Nuclear Information System (INIS)
Rosenberg, L.
1983-01-01
The theory of resonant reactions, in the projection-operator formulation of Feshbach, is generalized to account for the presence of an external electromagnetic field. The theory is used as the basis for the construction of low-frequency approximations for the transition amplitude. Results obtained here for scattering in a laser field confirm earlier versions of the low-frequency approximation when the resonances are isolated. However, if there are several closely spaced resonances additional terms must be included (their importance magnified by the appearance of near singularities) which account for the effect of radiative transitions between pairs of nearly degenerate resonant states. The weak-field limit of this result yields a low-frequency approximation for single-photon spontaneous bremsstrahlung which, through the inclusion of correction terms associated with closely spaced resonances, provides an improvement over the Feshbach-Yennie version derived some time ago. A separate treatment is required to deal with the limiting case of a static external field and this is worked out here in the context of a time-dependent formulation of the scattering problem. Linear and quadratic Stark splitting of the resonance positions, and resonance broadening due to the tunneling mechanism, are expected to play a significant role in the static limit and these effects are included in the approximation derived here for the transition amplitude
Electromagnetic Meson Production in the Nucleon Resonance Region
Energy Technology Data Exchange (ETDEWEB)
Volker Burkert; T.-S. H. Lee
2004-10-01
Recent experimental and theoretical advances in investigating electromagnetic meson production reactions in the nucleon resonance region are reviewed. The article gives a description of current experimental facilities with electron and photon beams and presents a unified derivation of most of the phenomenological approaches being used to extract the resonance parameters from the data. The analyses of {pi} and {eta} production data and the resulting transition form factors for the {Delta}(1232)P{sub 33}, N(1535)S{sub 11}, N(1440)P{sub 11}, and N(1520)D{sub 13} resonances are discussed in detail. The status of our understanding of the reactions with production of two pions, kaons, and vector mesons is also reviewed.
Resonant effects on the low frequency vlasov stability of axisymmetric field reversed configurations
International Nuclear Information System (INIS)
Finn, J.M.; Sudan, R.N.
We investigate the effect of particle resonances on low frequency MHD modes in field-reversed geometries, e.g., an ion ring. It is shown that, for sufficiently high field reversal, modes which are hydromagnetically stable can be driven unstable by ion resonances. The stabilizing effect of a toroidal magnetic field is discussed
Electromagnetically induced transparency resonances inverted in magnetic field
Energy Technology Data Exchange (ETDEWEB)
Sargsyan, A.; Sarkisyan, D., E-mail: davsark@yahoo.com, E-mail: david@ipr.sci.am [National Academy of Sciences of Armenia, Institute for Physical Research (Armenia); Pashayan-Leroy, Y.; Leroy, C. [Université de Bourgogne-Dijon, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS (France); Cartaleva, S. [Bulgarian Academy of Sciences, Institute of Electronics (Bulgaria); Wilson-Gordon, A. D. [Bar-Ilan University Ramat Gan, Department of Chemistry (Israel); Auzinsh, M. [University of Latvia, Department of Physics (Latvia)
2015-12-15
The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the {sup 87}Rb D{sub 1} line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ{sub rel} are used: an Rb cell with antirelaxation coating (L ∼ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.
Energy Technology Data Exchange (ETDEWEB)
Kasilov, Sergei V. [Fusion@ÖAW, Institut für Theoretische Physik—Computational Physics, Technische Universität Graz Petersgasse 16, A–8010 Graz (Austria); Institute of Plasma Physics National Science Center “Kharkov Institute of Physics and Technology” ul. Akademicheskaya 1, 61108 Kharkov (Ukraine); Kernbichler, Winfried; Martitsch, Andreas F.; Heyn, Martin F. [Fusion@ÖAW, Institut für Theoretische Physik—Computational Physics, Technische Universität Graz Petersgasse 16, A–8010 Graz (Austria); Maassberg, Henning [Max-Planck Institut für Plasmaphysik, D-17491 Greifswald (Germany)
2014-09-15
The toroidal torque driven by external non-resonant magnetic perturbations (neoclassical toroidal viscosity) is an important momentum source affecting the toroidal plasma rotation in tokamaks. The well-known force-flux relation directly links this torque to the non-ambipolar neoclassical particle fluxes arising due to the violation of the toroidal symmetry of the magnetic field. Here, a quasilinear approach for the numerical computation of these fluxes is described, which reduces the dimension of a standard neoclassical transport problem by one without model simplifications of the linearized drift kinetic equation. The only limiting condition is that the non-axisymmetric perturbation field is small enough such that the effect of the perturbation field on particle motion within the flux surface is negligible. Therefore, in addition to most of the transport regimes described by the banana (bounce averaged) kinetic equation also such regimes as, e.g., ripple-plateau and resonant diffusion regimes are naturally included in this approach. Based on this approach, a quasilinear version of the code NEO-2 [W. Kernbichler et al., Plasma Fusion Res. 3, S1061 (2008).] has been developed and benchmarked against a few analytical and numerical models. Results from NEO-2 stay in good agreement with results from these models in their pertinent range of validity.
Axisymmetric Alfvén resonances in a multi-component plasma at finite ion gyrofrequency
Directory of Open Access Journals (Sweden)
D. Yu. Klimushkin
2006-05-01
Full Text Available This paper deals with the spatial structure of zero azimuthal wave number ULF oscillations in a 1-D inhomogeneous multi-component plasma when a finite ion gyrofrequency is taken into account. Such oscillations may occur in the terrestrial magnetosphere as Pc1-3 waves or in the magnetosphere of the planet Mercury. The wave field was found to have a sharp peak on some magnetic surfaces, an analogy of the Alfvén (field line resonance in one-fluid MHD theory. The resonance can only take place for waves with frequencies in the intervals ω<ωch or Ω0<ω< ωcp, where ωch and ωcp are heavy and light ions gyrofrequencies, and Ω0 is a kind of hybrid frequency. Contrary to ordinary Alfvén resonance, the wave resonance under consideration takes place even at the zero azimuthal wave number. The radial component of the wave electric field has a pole-type singularity, while the azimuthal component is finite but has a branching point singularity on the resonance surface. The later singularity can disappear at some frequencies. In the region adjacent to the resonant surface the mode is standing across the magnetic shells.
Axisymmetric Alfvén resonances in a multi-component plasma at finite ion gyrofrequency
Directory of Open Access Journals (Sweden)
D. Yu. Klimushkin
2006-05-01
Full Text Available This paper deals with the spatial structure of zero azimuthal wave number ULF oscillations in a 1-D inhomogeneous multi-component plasma when a finite ion gyrofrequency is taken into account. Such oscillations may occur in the terrestrial magnetosphere as Pc1-3 waves or in the magnetosphere of the planet Mercury. The wave field was found to have a sharp peak on some magnetic surfaces, an analogy of the Alfvén (field line resonance in one-fluid MHD theory. The resonance can only take place for waves with frequencies in the intervals ω<ω_{ch} or Ω_{0}<ω< ω_{cp}, where ω_{ch} and ω_{cp} are heavy and light ions gyrofrequencies, and Ω_{0} is a kind of hybrid frequency. Contrary to ordinary Alfvén resonance, the wave resonance under consideration takes place even at the zero azimuthal wave number. The radial component of the wave electric field has a pole-type singularity, while the azimuthal component is finite but has a branching point singularity on the resonance surface. The later singularity can disappear at some frequencies. In the region adjacent to the resonant surface the mode is standing across the magnetic shells.
Quiescent H-mode operation using torque from non-axisymmetric, non-resonant magnetic fields
International Nuclear Information System (INIS)
Burrell, K.H.; Garofalo, A.M.; Osborne, T.H.; Snyder, P.B.; Solomon, W.M.; Park, J.-K.; Fenstermacher, M.E.; Orlov, D.M.
2013-01-01
Quiescent H-mode (QH-mode) sustained by magnetic torque from non-axisymmetric magnetic fields is a promising operating mode for future burning plasmas including ITER. Using magnetic torque from n = 3 fields to replace counter-I p torque from neutral beam injection, we have achieved long duration, counter-rotating QH-mode operation with neutral beam injection (NBI) torque ranging continuously from counter-I p up to co-I p values of about 1 N m. This co-I p torque is about 3 times the scaled torque that ITER will have. This range also includes operation at zero net NBI torque, applicable to rf wave heated plasmas. These n = 3 fields have been created using coils either inside or, most recently, outside the toroidal coils. Experiments utilized an ITER-relevant lower single-null plasma shape and were done with ITER-relevant values ν ped * ∼0.08, β T ped ∼ 1%$ and β N = 2. Discharges have confinement quality H 98y2 = 1.3, exceeding the value required for ITER. Initial work with low q 95 = 3.4 QH-mode plasmas transiently reached fusion gain values of G = β N H 89 /q 95 2 =0.4, which is the desired value for ITER; the limits on G have not yet been established. This paper also includes the most recent results on QH-mode plasmas run without n = 3 fields and with co-I p NBI; these shots exhibit co-I p plasma rotation and require NBI torque ⩾2 N m. The QH-mode work to date has made significant contact with theory. The importance of edge rotational shear is consistent with peeling–ballooning mode theory. We have seen qualitative and quantitative agreement with the predicted torque from neoclassical toroidal viscosity. (paper)
Analytic Solution of the Electromagnetic Eigenvalues Problem in a Cylindrical Resonator
Energy Technology Data Exchange (ETDEWEB)
Checchin, Mattia [Fermilab; Martinello, Martina [Fermilab
2016-10-06
Resonant accelerating cavities are key components in modern particles accelerating facilities. These take advantage of electromagnetic fields resonating at microwave frequencies to accelerate charged particles. Particles gain finite energy at each passage through a cavity if in phase with the resonating field, reaching energies even of the order of $TeV$ when a cascade of accelerating resonators are present. In order to understand how a resonant accelerating cavity transfers energy to charged particles, it is important to determine how the electromagnetic modes are exited into such resonators. In this paper we present a complete analytical calculation of the resonating fields for a simple cylindrical-shaped cavity.
A multi-purpose electromagnetic actuator for magnetic resonance elastography.
Feng, Yuan; Zhu, Mo; Qiu, Suhao; Shen, Ping; Ma, Shengyuan; Zhao, Xuefeng; Hu, Chun-Hong; Guo, Liang
2018-04-19
An electromagnetic actuator was designed for magnetic resonance elastography (MRE). The actuator is unique in that it is simple, portable, and capable of brain, abdomen, and phantom imagings. A custom-built control unit was used for controlling the vibration frequency and synchronizing the trigger signals. An actuation unit was built and mounted on the specifically designed clamp and holders for different imaging applications. MRE experiments with respect to gel phantoms, brain, and liver showed that the actuator could produce stable and consistent mechanical waves. Estimated shear modulus using local frequency estimate method demonstrated that the measurement results were in line with that from MRE studies using different actuation systems. The relatively easy setup procedure and simple design indicated that the actuator system had the potential to be applied in many different clinical studies. Copyright © 2018 Elsevier Inc. All rights reserved.
Wake-Field Wave Resonant Excitation in Magnetized Plasmas by Electromagnetic Pulse
International Nuclear Information System (INIS)
Milant'ev, V.P.; Turikov, V.A.
2006-01-01
In this paper the space charge wave excitation process at electromagnetic pulse propagation along external magnetic field in vicinity of electron cyclotron resonance. In hydrodynamic approach it is obtained an equation for plasma density under ponderomotive force action. With help of this equation we investigated a wake-field wave amplitude dependence from resonance detuning. The numerical simulation using a PIC method electromagnetic pulse propagation process in the resonant conditions was done
Resonant Electromagnetic Interaction in Low Energy Nuclear Reactions
Chubb, Scott
2008-03-01
Basic ideas about how resonant electromagnetic interaction (EMI) can take place in finite solids are reviewed. These ideas not only provide a basis for conventional, electron energy band theory (which explains charge and heat transport in solids), but they also explain how through finite size effects, it is possible to create many of the kinds of effects envisioned by Giuliano Preparata. The underlying formalism predicts that the orientation of the external fields in the SPAWAR protocolootnotetextKrivit, Steven B., New Energy Times, 2007, issue 21, item 10. http://newenergytimes.com/news/2007/NET21.htm^,ootnotetextSzpak, S.; Mosier-Boss, P.A.; Gordon, F.E. Further evidence of nuclear reactions in the Pd lattice: emission of charged particles. Naturwissenschaften 94,511(2007)..has direct bearing on the emission of high-energy particles. Resonant EMI also implies that nano-scale solids, of a particular size, provide an optimal environment for initiating Low Energy Nuclear Reactions (LENR) in the PdD system.
Zuffada, Cinzia; Crisp, David
1997-01-01
Reliable descriptions of the optical properties of clouds and aerosols are essential for studies of radiative transfer in planetary atmospheres. The scattering algorithms provide accurate estimates of these properties for spherical particles with a wide range of sizes and refractive indices, but these methods are not valid for non-spherical particles (e.g., ice crystals, mineral dust, and smoke). Even though a host of methods exist for deriving the optical properties of nonspherical particles that are very small or very large compared with the wavelength, only a few methods are valid in the resonance regime, where the particle dimensions are comparable with the wavelength. Most such methods are not ideal for particles with sharp edges or large axial ratios. We explore the utility of an integral equation approach for deriving the single-scattering optical properties of axisymmetric particles with large axial ratios. The accuracy of this technique is shown for spheres of increasing size parameters and an ensemble of randomly oriented prolate spheroids of size parameter equal to 10.079368. In this last case our results are compared with published results obtained with the T-matrix approach. Next we derive cross sections, single-scattering albedos, and phase functions for cylinders, disks, and spheroids of ice with dimensions extending from the Rayleigh to the geometric optics regime. Compared with those for a standard surface integral equation method, the storage requirement and the computer time needed by this method are reduced, thus making it attractive for generating databases to be used in multiple-scattering calculations. Our results show that water ice disks and cylinders are more strongly absorbing than equivalent volume spheres at most infrared wavelengths. The geometry of these particles also affects the angular dependence of the scattering. Disks and columns with maximum linear dimensions larger than the wavelength scatter much more radiation in the forward
Determination of the electromagnetic field in a high-Tc linear superconducting resonator
International Nuclear Information System (INIS)
Trotel, A.; Sautrot, S.; Pyee, M.
1994-01-01
In this paper, the electromagnetic field configuration in a linear SHTC resonator is described. Two areas are considered: 1) the superconducting strip, 2) the dielectric around the strip. The calculation is based on the current density given by Bowers for an infinite superconducting line. The current density in the resonator is defined by these relations and the resonance conditions. (orig.)
Guo, Yinghui; Yan, Lianshan; Pan, Wei; Luo, Bin; Wen, Kunhua; Guo, Zhen; Luo, Xiangang
2012-10-22
We investigate a plasmonic waveguide system based on side-coupled complementary split-ring resonators (CSRR), which exhibits electromagnetically induced transparency (EIT)-like transmission. LC resonance model is utilized to explain the electromagnetic responses of CSRR, which is verified by simulation results of finite difference time domain method. The electromagnetic responses of CSRR can be flexible handled by changing the asymmetry degree of the structure and the width of the metallic baffles. Cascaded CSRRs also have been studied to obtain EIT-like transmission at visible and near-infrared region, simultaneously.
Current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation
Directory of Open Access Journals (Sweden)
N Hatefi Kargan
2013-09-01
Full Text Available In this paper, current-voltage characteristic of a resonant tunneling diode under electromagnetic radiation has been calculated and compared with the results when there is no electromagnetic radiation. For calculating current -voltage characteristic, it is required to calculate the transmission coefficient of electrons from the well and barrier structures of this device. For calculating the transmission coefficient of electrons at the presence of electromagnetic radiation, Finite Difference Time Domain (FDTD method has been used and when there is no electromagnetic radiation Transfer Matrix Method (TMM and finite diffirence time domain method have been used. The results show that the presence of electromagnetic radiation causes resonant states other than principal resonant state (without presence of electromagnetic radiation to appear on the transmition coefficient curve where they are in distances from the principal peak and from each other. Also, the presence of electromagnetic radiation causes peaks other than principal peak to appear on the current-voltage characteristics of the device. Under electromagnetic radiation, the number of peaks on the current-voltage curve is smaller than the number of peaks on the current-voltage transmission coefficient. This is due to the fact that current-voltage curve is the result of integration on the energy of electrons, Thus, the sharper and low height peaks on the transmission coefficient do not appear on the current-voltage characteristic curve.
Quantum resonances of Landau damping in the electromagnetic response of metallic nanoslabs.
Castillo-López, S G; Makarov, N M; Pérez-Rodríguez, F
2018-05-15
The resonant quantization of Landau damping in far-infrared absorption spectra of metal nano-thin films is predicted within the Kubo formalism. Specifically, it is found that the discretization of the electromagnetic and electron wave numbers inside a metal nanoslab produces quantum nonlocal resonances well-resolved at slab thicknesses smaller than the electromagnetic skin depth. Landau damping manifests itself precisely as such resonances, tracing the spectral curve obtained within the semiclassical Boltzmann approach. For slab thicknesses much greater than the skin depth, the classical regime emerges. Here the results of the quantum model and the Boltzmann approach coincide. Our analytical study is in perfect agreement with corresponding numerical simulations.
Energy Technology Data Exchange (ETDEWEB)
Li, Hai-ming; Liu, Shao-bin, E-mail: lsb@nuaa.edu.cn; Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun [Key Laboratory of Radar Imaging and Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Shen-yun [Research Center of Applied Electromagnetics, Nanjing University of Information Science and Technology, Nanjing 210044 (China)
2015-03-16
In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.
International Nuclear Information System (INIS)
Hong, Liu; He, X.T.; Chen, S.G.; Zhang, W.Y.; He, X.T.; Hong, Liu
2004-01-01
We propose a new particle acceleration mechanism. Electrons can be accelerated to relativistic energy within a few electromagnetic wave cycles through the mechanism which is named electromagnetic and magnetic field resonance acceleration (EMRA). We find that the electron acceleration depends not only on the electromagnetic wave intensity, but also on the ratio between electron Larmor frequency and electromagnetic wave frequency. As the ratio approaches to unity, a clear resonance peak is observed, corresponding to the EMRA. Near the resonance regime, the strong magnetic fields still affect the electron acceleration dramatically. We derive an approximate analytical solution of the relativistic electron energy in adiabatic limit, which provides a full understanding of this phenomenon. In typical parameters of pulsar magnetospheres, the mechanism allows particles to increase their energies through the resonance of high magnetic field and high frequency electromagnetic wave in each electromagnetic wave period. The energy spectra of the accelerated particles exhibit the synchrotron radiation behavior. These can help to understand the remaining emission of high energy electron from radio pulsar within supernova remnant. The other potential application of our theory in fast ignition scheme of inertial confinement fusion is also discussed. (authors)
Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan
2016-01-01
Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties. PMID:26857034
Resonant emission of electromagnetic waves by plasma solitons
International Nuclear Information System (INIS)
Mironov, V.A.; Sergeev, A.M.; Khimich, A.V.
1988-01-01
The ability of plasma-wave solitons to radiate electromagnetic waves at the frequency of the natural oscillations of the field is considered. It is shown that this radiation is the main energy dissipation channel for strong plasma turbulence in a magnetoactive plasma. An interpretation is proposed for the artificial radio emission produced when the ionosphere is acted upon by beams of strong electromagnetic waves. The use of this phenomenon for plasma turbulence, particularly in the outer-space plasma near the earth, is discussed
Helicity amplitudes and electromagnetic decays of hyperon resonances
International Nuclear Information System (INIS)
Cauteren, T. van; Ryckebusch, J.; Metsch, B.; Petry, H.R.
2005-01-01
We present results for the helicity amplitudes of the lowest-lying hyperon resonances Y * , computed within the framework of the Bonn Constituent-Quark model, which is based on the Bethe-Salpeter approach. The seven parameters entering the model were fitted to the best-known baryon masses. Accordingly, the results for the helicity amplitudes are genuine predictions. Some hyperon resonances are seen to couple more strongly to a virtual photon with finite Q 2 than to a real photon. Other Y * 's, such as the S 01 (1670) Λ-resonance or the S 11 (1620) Σ-resonance, couple very strongly to real photons. We present a qualitative argument for predicting the behaviour of the helicity asymmetries of baryon resonances at high Q 2 . (orig.)
Deng, Wei; Wang, Ya
2017-09-01
This paper reports a dual resonant rectilinear-to-rotary oscillation converter (RROC) for low frequency broadband electromagnetic energy harvesting from ambient vibrations. An approximate theoretical model has been established to integrate the electromechanical coupling into a comprehensive electromagnetic-dynamic model of the dual resonant RROC. Numerical simulation has proved the nature of dual resonances by revealing that both the rectilinear resonance and the rotary resonance could be achieved when the stand-alone rectilinear oscillator (RLO) and the stand-alone rotary oscillator (RTO) were excited independently. Simulation on the magnetically coupled RROC has also shown that the rectilinear resonance and the rotary resonance could be obtained simultaneously in the low-frequency region (2-14 Hz) with well-defined restoring torque (M r ) and the initial rotation angle of the RLO (ψ). The magnetic interaction patterns between the rectilinear and the RTOs have been categorized based on aforementioned simulation results. Both simulation and experimental results have demonstrated broadband output attributing from the dual resonances. Experimental results have also indicated that the RROC could have wide bandwidth in a much lower frequency region (2-8 Hz) even without the rotary resonance as long as the system parameters are carefully tuned. Parameter analysis on different values of M r and ψ are experimentally carried out to provide a quantitative guidance of designing the RROC to achieve an optimal power density.
Sherkunov, Yury
2018-03-01
We study theoretically the van der Waals interaction between two atoms out of equilibrium with an isotropic electromagnetic field. We demonstrate that at large interatomic separations, the van der Waals forces are resonant, spatially oscillating, and nonreciprocal due to resonance absorption and emission of virtual photons. We suggest that the van der Waals forces can be controlled and manipulated by tuning the spectrum of artificially created random light.
A resonant electromagnetic vibration energy harvester for intelligent wireless sensor systems
Energy Technology Data Exchange (ETDEWEB)
Qiu, Jing, E-mail: jingqiu@cqu.edu.cn; Wen, Yumei; Li, Ping; Liu, Xin; Chen, Hengjia; Yang, Jin [Sensors and Instruments Research Center, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)
2015-05-07
Vibration energy harvesting is now receiving more interest as a means for powering intelligent wireless sensor systems. In this paper, a resonant electromagnetic vibration energy harvester (VEH) employing double cantilever to convert low-frequency vibration energy into electrical energy is presented. The VEH is made up of two cantilever beams, a coil, and magnetic circuits. The electric output performances of the proposed electromagnetic VEH have been investigated. With the enhancement of turns number N, the optimum peak power of electromagnetic VEH increases sharply and the resonance frequency deceases gradually. When the vibration acceleration is 0.5 g, we obtain the optimum output voltage and power of 9.04 V and 50.8 mW at frequency of 14.9 Hz, respectively. In a word, the prototype device was successfully developed and the experimental results exhibit a great enhancement in the output power and bandwidth compared with other traditional electromagnetic VEHs. Remarkably, the proposed resonant electromagnetic VEH have great potential for applying in intelligent wireless sensor systems.
Directory of Open Access Journals (Sweden)
Irena Cosic
2016-06-01
Full Text Available The meaning and influence of light to biomolecular interactions, and consequently to health, has been analyzed using the Resonant Recognition Model (RRM. The RRM proposes that biological processes/interactions are based on electromagnetic resonances between interacting biomolecules at specific electromagnetic frequencies within the infra-red, visible and ultra-violet frequency ranges, where each interaction can be identified by the certain frequency critical for resonant activation of specific biological activities of proteins and DNA. We found that: (1 the various biological interactions could be grouped according to their resonant frequency into super families of these functions, enabling simpler analyses of these interactions and consequently analyses of influence of electromagnetic frequencies to health; (2 the RRM spectrum of all analyzed biological functions/interactions is the same as the spectrum of the sun light on the Earth, which is in accordance with fact that life is sustained by the sun light; (3 the water is transparent to RRM frequencies, enabling proteins and DNA to interact without loss of energy; (4 the spectrum of some artificial sources of light, as opposed to the sun light, do not cover the whole RRM spectrum, causing concerns for disturbance to some biological functions and consequently we speculate that it can influence health.
International Nuclear Information System (INIS)
Soares, A A; De Araujo, Luis E E
2010-01-01
We study theoretically the interaction between an ultrashort pulse train and a three-level atom driven by a cw laser. We show that the pulse train can be employed to observe spectra of Autler-Townes doublet and electromagnetically induced transparency resonance that are time and frequency resolved. The observation of subnatural linewidth features associated with the electromagnetically induced transparency resonance is described. The temporal evolution of electromagnetically induced transparency of the pulse train is shown to exhibit new and different features compared to that of the related phenomenon of coherent population trapping. By matching the tooth separation of the frequency comb associated with the pulse train to that of the Autler-Townes doublet, quantum beats between the doublet components can be induced. We show that coherent accumulation of excitation plays a major role in the two studied phenomena.
Electromagnetic transitions between giant resonances within a continuum-RPA approach
Rodin, VA; Dieperink, AEL
2002-01-01
A general continuum-RPA approach is developed to describe electromagnetic transitions between giant resonances. Using a diagrammatic representation for the three-point Green's function, an expression for the transition amplitude is derived which allows one to incorporate effects of mixing of single
Electromagnetically induced transparency in planar metamaterials based on guided mode resonance
Sun, Yaru; Chen, Hang; Li, Xiangjun; Hong, Zhi
2017-06-01
We present and numerically demonstrate a novel, electromagnetically induced transparency (EIT) in planar metamaterials (MMs) based on guided mode resonance (GMR). The unit cell of the MM consists of two metallic ring resonators. The GMR with high quality factor (Q) is achieved by changing the distance between the two rings of the MM. Narrow EIT-like spectral response is realized by coupling between a high Q GMR and a low Q dipolar resonance of the MM. Our work could provide another efficient way towards the realization of EIT with large group index using very simple structures.
Directory of Open Access Journals (Sweden)
Yu-Xuan Fu
2018-02-01
Full Text Available The FitzHugh–Nagumo model is improved to consider the effect of the electromagnetic induction on single neuron. On the basis of investigating the Hopf bifurcation behavior of the improved model, stochastic resonance in the stochastic version is captured near the bifurcation point. It is revealed that a weak harmonic oscillation in the electromagnetic disturbance can be amplified through stochastic resonance, and it is the cooperative effect of random transition between the resting state and the large amplitude oscillating state that results in the resonant phenomenon. Using the noise dependence of the mean of interburst intervals, we essentially suggest a biologically feasible clue for detecting weak signal by means of neuron model with subcritical Hopf bifurcation. These observations should be helpful in understanding the influence of the magnetic field to neural electrical activity.
Resonant interactions between cometary ions and low frequency electromagnetic waves
Thorne, Richard M.; Tsurutani, Bruce T.
1987-01-01
The conditions for resonant wave amplification in a plasma with a ring-beam distribution which is intended to model pick-up ions in a cometary environment are investigated. The inclination between the interplanetary field and the solar wind is found to play a crucial role in governing both the resonant frequency and the growth rate of any unstable mode. It is suggested that the low-frequency MHD mode should experience the most rapid amplification for intermediate inclination. In the frame of the solar wind, such waves should propagate along the field in the direction upstream toward the sun with a phase speed lower than the beaming velocity of the pick-up ions. This mechanism may account for the presence of the interior MHD waves noted by satellites over a region surrounding comets Giacobini-Zinner and Halley.
Resonant absorption of electromagnetic waves in transition anisotropic media.
Kim, Kihong
2017-11-27
We study the mode conversion and resonant absorption phenomena occurring in a slab of a stratified anisotropic medium, optical axes of which are tilted with respect to the direction of inhomogeneity, using the invariant imbedding theory of wave propagation. When the tilt angle is zero, mode conversion occurs if the longitudinal component of the permittivity tensor, which is the one in the direction of inhomogeneity in the non-tilted case, varies from positive to negative values within the medium, while the transverse component plays no role. When the tilt angle is nonzero, the wave transmission and absorption show an asymmetry under the sign change of the incident angle in a range of the tilt angle, while the reflection is always symmetric. We calculate the reflectance, the transmittance and the absorptance for several configurations of the permittivity tensor and find that resonant absorption is greatly enhanced when the medium from the incident surface to the resonance region is hyperbolic than when it is elliptic. For certain configurations, the transmittance and absorptance curves display sharp peaks at some incident angles determined by the tilt angle.
International Nuclear Information System (INIS)
Burrell, K. H.; Garofalo, A. M; Osborne, T. H.; Schaffer, M. J.; Snyder, P. B.; Solomon, W. M.; Park, J.-K.; Fenstermacher, M. E.
2012-01-01
Results from recent experiments demonstrate that quiescent H-mode (QH-mode) sustained by magnetic torque from non-axisymmetric magnetic fields is a promising operating mode for future burning plasmas. Using magnetic torque from n=3 fields to replace counter-I p torque from neutral beam injection (NBI), we have achieved long duration, counter-rotating QH-mode operation with NBI torque ranging from counter-I p to up to co-I p values of 1-1.3 Nm. This co-I p torque is 3 to 4 times the scaled torque that ITER will have. These experiments utilized an ITER-relevant lower single-null plasma shape and were done with ITER-relevant values of ν ped * and β N ped . These discharges exhibited confinement quality H 98y2 =1.3, in the range required for ITER. In preliminary experiments using n=3 fields only from a coil outside the toroidal coil, QH-mode plasmas with low q 95 =3.4 have reached fusion gain values of G=β N H 89 /q 95 2 =0.4, which is the desired value for ITER. Shots with the same coil configuration also operated with net zero NBI torque. The limits on G and co-I p torque have not yet been established for this coil configuration. QH-mode work to has made significant contact with theory. The importance of edge rotational shear is consistent with peeling-ballooning mode theory. Qualitative and quantitative agreements with the predicted neoclassical toroidal viscosity torque is seen.
International Nuclear Information System (INIS)
Reiman, A.; Zarnstorff, M.; Mikkelsen, D.; Owen, L.; Mynick, H.; Hudson, S.; Monticello, D.
2005-01-01
A reference equilibrium for the U.S. National Compact Stellarator Experiment is predicted to be sufficiently close to quasi-symmetry to allow the plasma to flow in the toroidal direction with little viscous damping, yet to have sufficiently large deviations from quasi-symmetry that nonambipolarity significantly affects the physics of the shielding of resonant magnetic perturbations by plasma flow. The unperturbed velocity profile is modified by the presence of an ambipolar potential, which produces a broad velocity profile. In the presence of a resonant magnetic field perturbation, nonambipolar transport produces a radial current, and the resulting j x B force resists departures from the ambipolar velocity and enhances the shielding
International Nuclear Information System (INIS)
Zhu, Lei; Dong, Liang
2014-01-01
We numerically demonstrate that a broadband electromagnetically induced transparency–like (EIT-like) effect can be achieved in an all-dielectric microstructure consisting of a dielectric bar and six dielectric bricks. With proper excitations, the dielectric bar and bricks serve as bright and dark elements via the Mie electric and magnetic resonances, respectively. In particular, the mutual couplings between the Mie electric and magnetic resonances induce a broad transparency window. The nature of resonances of the broadband EIT-like effect in an all-dielectric microstructure is investigated by numerical simulation and a coupled oscillator model. Results reveal that significant enhancement of coupling interactions between dielectric resonators leads to a broadband EIT-like effect. Such a dielectric EIT-like structure is promising for future applications in nonlinear optics, slow light devices, and filters. (paper)
Multi-resonant electromagnetic shunt in base isolation for vibration damping and energy harvesting
Pei, Yalu; Liu, Yilun; Zuo, Lei
2018-06-01
This paper investigates multi-resonant electromagnetic shunts applied to base isolation for dual-function vibration damping and energy harvesting. Two multi-mode shunt circuit configurations, namely parallel and series, are proposed and optimized based on the H2 criteria. The root-mean-square (RMS) value of the relative displacement between the base and the primary structure is minimized. Practically, this will improve the safety of base-isolated buildings subjected the broad bandwidth ground acceleration. Case studies of a base-isolated building are conducted in both the frequency and time domains to investigate the effectiveness of multi-resonant electromagnetic shunts under recorded earthquake signals. It shows that both multi-mode shunt circuits outperform traditional single mode shunt circuits by suppressing the first and the second vibration modes simultaneously. Moreover, for the same stiffness ratio, the parallel shunt circuit is more effective at harvesting energy and suppressing vibration, and can more robustly handle parameter mistuning than the series shunt circuit. Furthermore, this paper discusses experimental validation of the effectiveness of multi-resonant electromagnetic shunts for vibration damping and energy harvesting on a scaled-down base isolation system.
[Patient exposure to electromagnetic fields in magnetic resonance scanners: a review].
Guibelalde del Castillo, E
2013-12-01
The use of non-ionizing electromagnetic fields in the low frequency end of the electromagnetic spectrum and static fields, radiofrequencies (RF), and microwaves is fundamental both in modern communication systems and in diagnostic medical imaging techniques like magnetic resonance imaging (MRI). The proliferation of these applications in recent decades has led to intense activity in developing regulations to guarantee their safety and to the establishment of guidelines and legal recommendations for the public, workers, and patients. In April 2012 it was foreseen that the European Parliament and Council would approve and publish a directive on the minimum health and safety requirements regarding the exposure of workers to the risks arising from electromagnetic fields, which would modify Directive 2004/40/EC. New studies related to the exposure to electromagnetic radiation and its impact on health published in recent years have led to a new postponement, and it is now foreseen that the directive will come into effect in October 2013. One of the most noteworthy aspects of the new version of the directive is the exclusion of the limits of occupational exposure to electromagnetic fields in the clinical use of MRI. In exchange for this exception, physicians and experts in protection against non-ionizing radiation are asked to make additional efforts to train workers exposed to non-ionizing radiation and to establish mechanisms to guarantee the correct application of non-ionizing electromagnetic fields in patients, along similar lines to the principles of justification and optimization established for ionizing radiation. On the basis of the most recently published studies, this article reviews some safety-related aspects to take into account when examining patients with MRI with high magnetic fields. Copyright © 2013 SERAM. Published by Elsevier Espana. All rights reserved.
International Nuclear Information System (INIS)
Li, Xianping; Wei, Zhongchao; Liu, Yuebo; Zhong, Nianfa; Tan, Xiaopei; Shi, Songsong; Liu, Hongzhan; Liang, Ruisheng
2016-01-01
We have demonstrated the analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator. A reasonable analysis of the transmission feature based on the temporal coupled-mode theory is given and shows good agreement with the Finit-Difference Time-Domain simulation. The transparency window can be easily tuned by changing the geometrical parameters and the insulator filled in the resonator. The transmission of the resonator system is close to 80% and the full width at half maximum is less than 46 nm. The sensitivity of the structure is about 812 nm/RIU. These characteristics make the new system with potential to apply for optical storage, ultrafast plasmonic switch and slow-light devices.
Energy Technology Data Exchange (ETDEWEB)
Li, Xianping; Wei, Zhongchao, E-mail: wzc@scnu.edu.cn; Liu, Yuebo; Zhong, Nianfa; Tan, Xiaopei; Shi, Songsong; Liu, Hongzhan; Liang, Ruisheng
2016-01-08
We have demonstrated the analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator. A reasonable analysis of the transmission feature based on the temporal coupled-mode theory is given and shows good agreement with the Finit-Difference Time-Domain simulation. The transparency window can be easily tuned by changing the geometrical parameters and the insulator filled in the resonator. The transmission of the resonator system is close to 80% and the full width at half maximum is less than 46 nm. The sensitivity of the structure is about 812 nm/RIU. These characteristics make the new system with potential to apply for optical storage, ultrafast plasmonic switch and slow-light devices.
Elnaggar, Sameh Y.
2017-02-01
Similar to the hybridization of three atoms, three coupled resonators interact to form bonding, anti-bonding, and non-bonding modes. The non-bonding mode enables an electromagnetic induced transparency like transfer of energy. Here, the non-bonding mode, resulting from the strong electric coupling of two dielectric resonators and an enclosure, is exploited to show that it is feasible to transfer power over a distance comparable to the operating wavelength. In this scheme, the enclosure acts as a mediator. The strong coupling permits the excitation of the non-bonding mode with high purity. This approach is different from resonant inductive coupling, which works in the sub-wavelength regime. Optimal loads and the corresponding maximum efficiency are determined using two independent methods: Coupled Mode Theory and Circuit modelling. It is shown that, unlike resonant inductive coupling, the figure of merit depends on the enclosure quality and not on the load, which emphasizes the role of the enclosure as a mediator. Briefly after the input excitation is turned on, the energy in the receiver builds up via all coupled and spurious modes. As time elapses, all modes except the non-bonding cease to sustain. Due to the strong coupling between the dielectrics and the enclosure, such systems have unique properties such as high and uniform efficiency over large distances and minimal fringing fields. These properties suggest that electromagnetic induced transparency like schemes that rely on the use of dielectric resonators can be used to power autonomous systems inside an enclosure or find applications when exposure to the fields needs to be minimal. Finite Element computations are used to verify the theoretical predictions by determining the transfer efficiency, field profile, and coupling coefficients for two different systems. It is shown that the three resonators must be present for efficient power transfer; if one or more are removed, the transfer efficiency reduces
Verginadis, Ioannis I; Simos, Yannis V; Velalopoulou, Anastasia P; Vadalouca, Athina N; Kalfakakou, Vicky P; Karkabounas, Spyridon Ch; Evangelou, Angelos M
2012-12-01
Exposure to various types of electromagnetic fields (EMFs) affects pain specificity (nociception) and pain inhibition (analgesia). Previous study of ours has shown that exposure to the resonant spectra derived from biologically active substances' NMR may induce to live targets the same effects as the substances themselves. The purpose of this study is to investigate the potential analgesic effect of the resonant EMFs derived from the NMR spectrum of morphine. Twenty five Wistar rats were divided into five groups: control group; intraperitoneal administration of morphine 10 mg/kg body wt; exposure of rats to resonant EMFs of morphine; exposure of rats to randomly selected non resonant EMFs; and intraperitoneal administration of naloxone and simultaneous exposure of rats to the resonant EMFs of morphine. Tail Flick and Hot Plate tests were performed for estimation of the latency time. Results showed that rats exposed to NMR spectrum of morphine induced a significant increase in latency time at time points (p spectrum of morphine. Our results indicate that exposure of rats to the resonant EMFs derived from the NMR spectrum of morphine may exert on animals similar analgesic effects to morphine itself.
Bouhrara, M.; Abou-Hamad, E.; Alabedi, G.; Al-Taie, I.; Kim, Y.; Wagberg, T.; Goze-Bac, C.
2013-01-01
The nuclear magnetic resonance (NMR) analytical technique was used to investigate the double walled carbon nanotubes (DWNTs) electromagnetic properties of inner walls. The local magnetic and electronic properties of inner nanotubes in DWNTs were analyzed using 25% 13C enriched C 60 by which the effect of dipolar coupling could be minimized. The diamagnetic shielding was determined due to the ring currents on outer nanotubes in DWNTs. The NMR chemical shift anisotropy (CSA) spectra and spin-lattice relaxation studies reveal the metallic properties of the inner nanotubes with a signature of the spin-gap opening below 70 K.
Huang, Yanyi; Poon, Joyce K. S.; Liang, Wei; Yariv, Amnon; Zhang, Cheng; Dalton, Larry R.
2005-08-01
By combining a solid-state photoreaction model with the modal solutions of an optical waveguide, we simulate the refractive index change due to the photobleaching of CLD-1 chromophores in an amorphous polycarbonate microring resonator. The simulation agrees well with experimental results. The photobleaching quantum efficiency of the CLD-1 chromophores is determined to be 0.65%. The combined modeling of the electromagnetic wave propagation and photoreaction precisely illustrates the spatial and temporal evolution of the optical properties of the polymer material as manifested in the refractive index and their effects on the modal and physical properties of the optical devices.
Bogatskaya, A. V.; Klenov, N. V.; Tereshonok, M. V.; Adjemov, S. S.; Popov, A. M.
2018-05-01
We present an analysis of the possibility of penetrating electromagnetic waves through opaque media using an optical-mechanical analogy. As an example, we consider the plasma sheath surrounding the vehicle as a potential barrier and analyze the overcoming of radiocommunication blackout problem. The idea is to embed a «resonator» between the surface on the vehicle and plasma sheath which is supposed to provide an effective tunneling of the signal to the receiving antenna. We discuss the peculiarities of optical mechanical analogy applicability and analyze the radio frequency wave tunneling regime in detail. The cases of normal and oblique incidence of radiofrequency waves on the vehicle surface are studied.
Narrowing of electromagnetically induced transparency resonance in a Doppler-broadened medium
International Nuclear Information System (INIS)
Javan, Ali; Kocharovskaya, Olga; Lee Hwang; Scully, Marlan O.
2002-01-01
We derive an analytic expression for the linewidth of electromagnetically induced transparency (EIT) resonance in a Doppler-broadened system. It is shown here that for relatively low intensity of the driving field the EIT linewidth is proportional to the square root of intensity and is independent of the Doppler width, similar to the laser-induced line narrowing effect described by Feld and Javan. In the limit of high intensity we recover the usual power-broadening case where the EIT linewidth is proportional to the intensity and inversely proportional to the Doppler width
Energy Technology Data Exchange (ETDEWEB)
Han, Song; Yang, Helin [College of Physical Science and Technology, Central China Normal University, Wuhan (China); Cong, Lonqing; Singh, Ranjan [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore); Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore (Singapore)
2016-05-15
Toroidal multipoles have recently been explored in various scientific communities, ranging from atomic and molecular physics, electrodynamics, and solid-state physics to biology. Here we experimentally and numerically demonstrate a three-dimensional toroidal metamaterial where two different toroidal dipoles along orthogonal directions have been observed. The chosen toroidal metamaterial also simultaneously supports Fano resonance and the classical analog of electromagnetically induced transparency (EIT) phenomena in the transmission spectra that originate from the electric-toroidal dipole and electric-magnetic dipole destructive interference. The intriguing properties of the toroidal resonances may open up avenues for applications in toroidal moments generator, sensing and slow-light devices. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Artemyev, A V; Neishtadt, A I; Zelenyi, L M; Vainchtein, D L
2010-12-01
We present an analytical and numerical study of the surfatron acceleration of nonrelativistic charged particles by electromagnetic waves. The acceleration is caused by capture of particles into resonance with one of the waves. We investigate capture for systems with one or two waves and provide conditions under which the obtained results can be applied to systems with more than two waves. In the case of a single wave, the once captured particles never leave the resonance and their velocity grows linearly with time. However, if there are two waves in the system, the upper bound of the energy gain may exist and we find the analytical value of that bound. We discuss several generalizations including the relativistic limit, different wave amplitudes, and a wide range of the waves' wavenumbers. The obtained results are used for qualitative description of some phenomena observed in the Earth's magnetosphere. © 2010 American Institute of Physics.
Bagci, Fulya; Akaoglu, Baris
2017-08-01
We present a metamaterial configuration exhibiting single and multi-band electromagnetic induced transparency (EIT)-like properties. The unit cell of the single band EIT-like metamaterial consists of a multi-split ring resonator surrounded by a split ring resonator. The multi-split ring resonator acts as a quasi-dark or dark resonator, depending on the polarization of the incident wave, and the split ring resonator serves as the bright resonator. Combination of these two resonators results in a single band EIT-like transmission inside the stop band. EIT-like transmission phenomenon is also clearly observed in the measured transmission spectrum at almost the same frequencies for vertical and horizontal polarized waves, and the numerical results are verified for normal incidence. Moreover, multi-band transmission windows are created within a wide band by combining the two slightly different single band EIT-like metamaterial unit cells that exhibit two different coupling strengths inside a supercell configuration. Group indices as high as 123 for single band and 488 for tri-band transmission, accompanying with high transmission rates (over 80%), are achieved, rendering the metamaterial very suitable for multi-band slow light applications. It is shown that the group delay of the propagating wave can be increased and dynamically controlled by changing the polarization angle. Multi-band EIT-like transmission is also verified experimentally, and a good agreement with simulations is obtained. The proposed novel methodology for obtaining multi-band EIT, which takes advantage of a supercell configuration by hosting slightly different configured unit cells, can be utilized for easily formation and manipulation of multi-band transmission windows inside a stop band.
Autler-Townes effect in a strongly driven electromagnetically induced transparency resonance
International Nuclear Information System (INIS)
Yang Lijun; Zhang Lianshui; Li Xiaoli; Han Li; Fu Guangsheng; Manson, Neil B.; Suter, Dieter; Wei Changjiang
2005-01-01
In this paper we study the nonlinear behavior of an electromagnetically induced transparency (EIT) resonance subject to a coherent driving field. The EIT is associated with a Λ three-level system where two hyperfine levels within an electronic ground state are coupled to a common excited state level by a coupling field and a probe field. In addition there is an radio-frequency (rf) field driving a hyperfine transition within the ground state. The paper contrasts two different situations. In one case the rf-driven transition shares a common level with the probed transition and in the second case it shares a common level with the coupled transition. In both cases the EIT resonance is split into a doublet and the characteristics of the EIT doublet are determined by the strength and frequency of the rf-driving field. The doublet splitting originates from the rf-field induced dynamic Stark effect and has close analogy with the Autler-Townes effect observed in three-level pump-probe spectroscopy study. The situation changes when the rf field is strong and the two cases are very different. One is analogous to two Λ three-level systems with EIT resonance associated with each. The other corresponds to a doubly driven three-level system with rf-field-induced electromagnetically induced absorption resonance. The two situations are modeled using numerical solutions of the relevant equation of motion of density matrix. In addition a physical account of their behaviors is given in terms of a dressed state picture
International Nuclear Information System (INIS)
Shvets, G.; Tushentsov, M.; Tokman, M.D.; Kryachko, A.
2005-01-01
Propagation of electromagnetic waves in magnetized plasma near the electron cyclotron frequency can be strongly modified by adding a weak magnetic undulator. For example, both right- and left-hand circularly polarized waves can propagate along the magnetic field without experiencing resonant absorption. This effect of entirely eliminating electron cyclotron heating is referred to as the undulator-induced transparency (UIT) of the plasma, and is the classical equivalent of the well-known quantum mechanical effect of electromagnetically induced transparency. The basics of UIT are reviewed, and various ways in which UIT can be utilized to achieve exotic propagation properties of electromagnetic waves in plasmas are discussed. For example, UIT can dramatically slow down the waves' group velocity, resulting in the extreme compression of the wave energy in the plasma. Compressed waves are polarized along the propagation direction, and can be used for synchronous electron or ion acceleration. Strong coupling between the two wave helicities are explored to impart the waves with high group velocities ∂ω/∂k for vanishing wave numbers k. Cross-helicity coupling for realistic density and magnetic field profiles are examined using a linearized fluid code, particle-in-cell simulations, and ray-tracing WKB calculations
Ribatti, Valentina; Santini, Luca; Forleo, Giovanni B; Della Rocca, Domenico; Panattoni, Germana; Scali, Marta; Schirripa, Valentina; Danisi, Nicola; Ammirati, Fabrizio; Santini, Massimo
2017-04-01
In the last decades we are observing a continuous increase in the number of patients wearing cardiac implantable electronic devices (CIEDs). At the same time, we face daily with a domestic and public environment featured more and more by the presence and the utilization of new emitters and finally, more medical procedures are based on electromagnetic fields as well. Therefore, the topic of the interaction of devices with electromagnetic interference (EMI) is increasingly a real and actual problem.In the medical environment most attention is paid to magnetic resonance, nevertheless the risk of interaction is present also with ionizing radiation, electrical nerve stimulation and electrosurgery. In the non-medical environment, most studies reported in the literature focused on mobile phones, metal detectors, as well as on headphones or digital players as potential EMI sources, but many other instruments and tools may be intentional or non-intentional sources of electromagnetic fields.CIED manufacturers are more and more focusing on new technological features in order to make implantable devices less susceptible to EMI. However, patients and emitter manufacturers should be aware that limitations exist and that there is not complete immunity to EMI.
Single and multiple electromagnetic scattering by dielectric obstacles from a resonance perspective
International Nuclear Information System (INIS)
Riley, D.J.
1987-03-01
A new application of the singularity expansion method (SEM) is explored. This application combines the classical theory of wave propagation through a multiple-scattering environment and the SEM. Because the SEM is generally considered to be a theory for describing surface currents on conducting scatters, extensions are made which permit, under certain conditions, a singularity expansion representation for the electromagnetic field scattered by a dielectric scatterer. Application of this expansion is then made to the multiple-scattering case using both single and multiple interactions. A resonance scattering tensor form is used for the SEM description which leds to an associated tensor form for the solution to the multiple-scattering problem with each SEM pole effect appearing explicitly. The coherent field is determined for both spatial and SEM parameter random variations. A numerical example for the case of an ensemble of dielectric spheres which possess frequency-dependent loss is also made. Accurate resonance expansions for the single-scattering problem are derived, and resonance trajectories based on the Debye relaxation model for the refractive index are introduced. Application of these resonance expansions is then made to the multiple-scattering results for a slab containing a distribution of spheres with varying radii. Conditions are discussed which describe when the hybrid theory is appropriate. 53 refs., 21 figs., 9 tabs
High-quality electromagnetically-induced absorption resonances in a buffer-gas-filled vapour cell
Brazhnikov, D. V.; Ignatovich, S. M.; Vishnyakov, V. I.; Skvortsov, M. N.; Andreeva, Ch; Entin, V. M.; Ryabtsev, I. I.
2018-02-01
Magneto-optical subnatural-linewidth resonances of electromagnetically-induced absorption (EIA) in an alkali vapour cell have been experimentally studied. The observation configuration includes using two counter-propagating pumps and probe light waves with mutually orthogonal linear polarizations, exciting an open optical transition in the 87Rb D 1 line in the presence of argon buffer gas. The EIA signals registered in a probe-wave transmission reach an unprecedented contrast of about 135% with respect to the wide ‘Doppler’ absorption pedestal and 29% with respect to the level of background transmission signal. These contrast values correspond to a relatively small resonance full width at half maximum of about 7.2 mG (5.2 kHz). The width of the narrowest EIA resonance observed is about 2.1 mG (1.5 kHz). To our knowledge, such a large relative contrast at the kHz-width is the record result for EIA resonances. In general, the work has experimentally proved that the magneto-optical scheme used has very good prospects for various quantum technologies (quantum sensors of weak magnetic fields, optical switches and other photonic elements).
Grant, Ian S
1990-01-01
The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition F. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw the Physics of Stars Second Edition A. C. Phillips Computing for Scient
Moon, Han Seb; Noh, Heung-Ryoul
2013-03-25
We have experimentally and theoretically studied resonant two-photon absorption (TPA) and electromagnetically induced transparency (EIT) in the open ladder-type atomic system of the 5S(1/2) (F = 1)-5P(3/2) (F' = 0, 1, 2)-5D(5/2) (F″ = 1, 2, 3) transitions in (87)Rb atoms. As the coupling laser intensity was increased, the resonant TPA was transformed to EIT for the 5S(1/2) (F = 1)-5P(3/2) (F' = 2)-5D(5/2) (F″ = 3) transition. The transformation of resonant TPA into EIT was numerically calculated for various coupling laser intensities, considering all the degenerate magnetic sublevels of the 5S(1/2)-5P(3/2)-5D(5/2) transition. From the numerical results, the crossover from TPA to EIT could be understood by the decomposition of the spectrum into an EIT component owing to the pure two-photon coherence and a TPA component caused by the mixed term.
Athe, Pratik; Srivastava, Sanjay; Thapa, Khem B.
2018-04-01
In the present work, we demonstrate the generation of optical Fano resonance and electromagnetically induced reflectance (EIR) in one-dimensional superconducting photonic crystal (1D SPC) by numerical simulation using transfer matrix method as analysis tool. We investigated the optical response of 1D SPC structure consisting of alternate layer of two different superconductors and observed that the optical spectra of this structure exhibit two narrow reflectance peaks with zero reflectivity of sidebands. Further, we added a dielectric cap layer to this 1D SPC structure and found that addition of dielectric cap layer transforms the line shape of sidebands around the narrow reflectance peaks which leads to the formation of Fano resonance and EIR line shape in reflectance spectra. We also studied the effects of the number of periods, refractive index and thickness of dielectric cap layer on the lineshape of EIR and Fano resonances. It was observed that the amplitude of peak reflectance of EIR achieves 100% reflectance by increasing the number of periods.
Scattering of electromagnetic pulses by metal nanospheres in the vicinity of a Fano-like resonance
International Nuclear Information System (INIS)
Astapenko, V.A.; Svita, S.Yu.
2015-01-01
In the work, radiation scattering by metal nanospheres in a dielectric matrix in case of ultrashort and long electromagnetic pulses is studied theoretically. Spectral efficiencies of backward and forward scattering by silver nanospheres in glass are calculated with the use of experimental data on the dielectric permittivity of silver. The presence of Fano-like resonances in spectral dependences of scattering efficiency caused by interference of dipole and quadrupole scatterings is shown. Backward and forward scattering of ultrashort pulses is calculated and analyzed. The obtained dependences of the total probability of scattering (during all time of the action of a pulse) on pulse duration demonstrate an essential distinction between an ultrashort case and a long pulse limit
Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin
2016-12-12
The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices.
Online monitoring of pipe wall thinning by electromagnetic acoustic resonance method
International Nuclear Information System (INIS)
Urayama, Ryoichi; Takagi, Toshiyuki; Uchimoto, Tetsuya; Kanemoto, Shigeru
2013-01-01
The electromagnetic acoustic resonance (EMAR) method provides accurate and stable evaluation in high temperature environment, and it is an effective tool for online monitoring. In this study, the EMAR method and the superposition of the n-th compression (SNC) for data processing are applied to online monitoring of pipe wall thinning, and the accuracy and reliability of the measurements are demonstrated through field tests using a large-scale corrosion test loop at high temperature. To measure the thickness of pipes with complicated wall thinning, the SNC extracts thickness information from the spectral responses of the EMAR. Results from monitoring test show that EMAR with SNC can evaluate pipe wall thinning with an accuracy of 10 μm at 165degC. In addition, time evaluation of evaluated thickness decreases monotonically all over the test duration, which indicates high stability of this measurement technique. (author)
International Nuclear Information System (INIS)
Spreemann, Dirk; Hoffmann, Daniel; Folkmer, Bernd; Manoli, Yiannos
2008-01-01
This paper presents a design and optimization strategy for resonant electromagnetic vibration energy harvesting devices. An analytic expression for the magnetic field of cylindrical permanent magnets is used to build up an electromagnetic subsystem model. This subsystem is used to find the optimal resting position of the oscillating mass and to optimize the geometrical parameters (shape and size) of the magnet and coil. The objective function to be investigated is thereby the maximum voltage output of the transducer. An additional mechanical subsystem model based on well-known equations describing the dynamics of spring–mass–damper systems is established to simulate both nonlinear spring characteristics and the effect of internal limit stops. The mechanical subsystem enables the identification of optimal spring characteristics for realistic operation conditions such as stochastic vibrations. With the overall transducer model, a combination of both subsystems connected to a simple electrical circuit, a virtual operation of the optimized vibration transducer excited by a measured random acceleration profile can be performed. It is shown that the optimization approach results in an appreciable increase of the converter performance
Tay, Z. J.; Soh, W. T.; Ong, C. K.
2018-04-01
In this paper, we propose a new method of controlling microwave transmission from Electromagnetically Induced Absorption (EIA) to Electromagnetically Induced Transparency (EIT). EIA describes the state where the system strongly absorbs microwaves, whereas EIT describes the state in which the system is transparent to microwaves. Control is achieved via coupling of the 3 GHz photon mode of a metamaterial Split Ring Resonator (SRR) to the spin wave magnon modes of a Yttrium Iron Garnet (YIG) bulk. The system is described by a 2-body interaction matrix with an additional fitting parameter τ which takes into account the fact that the microstrip feed line could excite the SRR as well as the YIG. The parameter τ reveals the effect of geometry and shielding on the coupling behaviour and gives rise to unique physics. In low τ (τ ⩽ 2) configurations, only EIT is reported. However, in high τ (τ ≈ 10) configurations, EIA is reported. Furthermore, we report that the system can be easily changed from a low τ to high τ configuration by shielding the SRR from the microstrip with a thin metal piece. Varying the τ parameter through shielding is thus proposed as a new method of controlling the microwave transmission at the coupling region.
International Nuclear Information System (INIS)
Wen, Shulai; Liu, Ying; Zhao, Xiuchen; Cheng, Jingwei; Li, Hong
2014-01-01
Hcp-cobalt particles were successfully prepared by a liquid phase reduction method, and the microstructure, static magnetic properties, electromagnetic and microwave absorption properties of the cobalt particles with irregular shape were investigated in detail. The measured results indicate that the saturation magnetization was less than that of hcp-Co single crystals, and the coercivity was larger than that of bulk cobalt crystal. The permittivity presents multi-nonlinear dielectric resonance, which may result from the irregular shape containing parts of cutting angle of dodecahedron of cobalt particles. The real part of permeability decreases with the frequency, and the imaginary part has a wide resonant peak. The paraffin-based composite containing 70 wt% cobalt particles possessed strong absorption characteristics with a minimum RL of −38.97 dB at 10.81 GHz and an absorption band with RL under −10 dB from 8.72 to 13.26 GHz when the thickness is 1.8 mm, which exhibits excellent microwave absorption in middle and high frequency. The architectural design of material morphologies is important for improving microwave absorption properties toward future application. - Highlights: • Hcp-cobalt particles were prepared by a liquid phase reduction method. • The saturation magnetization was less than that of hcp-Co single crystals. • The permittivity presents multi-nonlinear dielectric resonance. • The real part of permeability decreases with frequency, and the imaginary part presents a wide resonant peak. • The paraffin-based composite possessed a minimum RL of −38.97 dB at 10.81 GHz
International Nuclear Information System (INIS)
Zhen-Peng, Su; Hui-Nan, Zheng
2009-01-01
The bounce-averaged Fokker–Planck equation is solved to study the relativistic electron phase space density (PSD) evolution in the outer radiation belt due to resonant interactions with plasmaspheric plume electromagnetic ion cyclotron (EMIC) waves. It is found that the PSDs of relativistic electrons can be depleted by 1–3 orders of magnitude in 5h, supporting the previous finding that resonant interactions with EMIC waves may account for the frequently observed relativistic electron flux dropouts in the outer radiation belt during the main phase of a storm. The significant precipitation loss of ∼MeV electrons is primarily induced by the EMIC waves in H + and He + bands. The rapid remove of highly relativistic electrons (> 5 MeV) is mainly driven by the EMIC waves in O + band at lower pitch-angles, as well as the EMIC waves in H + and He + bands at larger pitch-angles. Moreover, a stronger depletion of relativistic electrons is found to occur over a wider pitch angle range when EMIC waves are centering relatively higher in the band
Non-resonant electromagnetic energy harvester for car-key applications
Li, X.; Hehn, T.; Thewes, M.; Kuehne, I.; Frey, A.; Scholl, G.; Manoli, Y.
2013-12-01
This paper presents a novel non-resonant electromagnetic energy harvester for application in a remote car-key, to extend the lifetime of the battery or even to realize a fully energy autonomous, maintenance-free car-key product. Characteristic for a car-key are low frequency and large amplitude motions during normal daily operation. The basic idea of this non-resonant generator is to use a round flat permanent magnet moving freely in a round flat cavity, which is packaged on both sides by printed circuit boards embedded with multi-layer copper coils. The primary goal of this structure is to easily integrate the energy harvester with the existing electrical circuit module into available commercial car-key designs. The whole size of the energy harvester is comparable to a CR2032 coin battery. To find out the best power-efficient and optimal design, several magnets with different dimensions and magnetizations, and various layouts of copper coils were analysed and built up for prototype testing. Experimental results show that with an axially magnetized NdFeB magnet and copper coils of design variant B a maximum open circuit voltage of 1.1V can be observed.
A novel noncontact electromagnetic field-based sensor for the monitoring of resonant fatigue tests
International Nuclear Information System (INIS)
Nam, Si-Byung; Yun, Gun Jin; Binienda, Wieslaw; Carletta, Joan; Kim, Dong-Han
2011-01-01
In this paper, a prototype of an electromagnetic field-based (EFB) vibration sensor that uses a novel sensing technique to monitor the resonant fatigue testing of a conductive and/or ferromagnetic target specimen is presented. The distance from the target to a coil within the sensor affects the impedance of the coil. The electronic circuitry for the sensor consists of a relaxation oscillator, an embedded microprocessor module and a high-speed digital-to-analog converter. The impedance of the coil determines the frequency of oscillation of the relaxation oscillator's output, so that vibration of the target causes changes in the oscillation frequency. A timer in the embedded microprocessor module is used to count the oscillations, producing a digital signal that indicates the coil-to-target distance. The digital signal is instantaneously converted to an analog signal to produce the sensor's output. The key technologies proposed include: (1) a novel timer counting method using the input capture functionality and timer of the embedded microprocessor module and (2) significant simplification of the analog electronic circuitry. The performance of the proposed sensor has been verified using AISI 1095 carbon steel and Al6061–T6 aluminum alloy specimens during resonant fatigue tests. The sensor shows a good linearity between displacement amplitudes and output voltages
International Nuclear Information System (INIS)
Chang, Yoon Do; Yim, Seong Woo; Hwang, Si Dole
2013-01-01
The contactless power transfer (CPT) systems have been recently gaining popularity widely since it is an available option to realize the power delivery and storage with connector-free devices across a large air gap. Especially, the CPT with electromagnetic resonance coupling method is possible to exchange energy within 2 m efficiently. However, the power transfer efficiency of CPT in commercialized products has been limited because the impedance matching of coupled coils is sensitive. As a reasonable approach, we combined the CPT system with HTS wire technology and called as, superconducting contactless power transfer (SUCPT) system. Since the superconducting coils have an enough current density, the superconducting antenna and receiver coils at CPT system have a merit to deliver and receive a mass amount of electric energy. In this paper, we present the feasibility of the SUCPT system and examine the transmission properties of SUCPT phenomenon between room temperature and very low temperature at 77 K as long as the receiver is within 1.0 m distance.
International Nuclear Information System (INIS)
Geng, L. S.; Camalich, J. Martin; Vacas, M. J. Vicente
2009-01-01
We present a calculation of the leading SU(3)-breaking O(p 3 ) corrections to the electromagnetic moments and charge radius of the lowest-lying decuplet resonances in covariant chiral perturbation theory. In particular, the magnetic dipole moment of the members of the decuplet is predicted fixing the only low-energy constant (LEC) present up to this order with the well-measured magnetic dipole moment of the Ω - . We predict μ Δ ++ =6.04(13) and μ Δ + =2.84(2), which agree well with the current experimental information. For the electric quadrupole moment and the charge radius, we use state-of-the-art lattice QCD results to determine the corresponding LECs, whereas for the magnetic octupole moment there is no unknown LEC up to the order considered here, and we obtain a pure prediction. We compare our results with those reported in large N c , lattice QCD, heavy-baryon chiral perturbation theory, and other models.
Temperature elevation in the fetus from electromagnetic exposure during magnetic resonance imaging
Energy Technology Data Exchange (ETDEWEB)
Kikuchi, Satoru; Ito, Koichi [Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Saito, Kazuyuki; Takahashi, Masaharu [Research Center for Frontier Medical Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)], E-mail: kikuchi@graduate.chiba-u.jp
2010-04-21
This study computationally assessed the temperature elevations due to electromagnetic wave energy deposition during magnetic resonance imaging in non-pregnant and pregnant woman models. We used a thermal model with thermoregulatory response of the human body for our calculations. We also considered the effect of blood temperature variation on body core temperature. In a thermal equilibrium state, the temperature elevations in the intrinsic tissues of the woman and fetal tissues were 0.85 and 0.61 deg. C, respectively, at a whole-body averaged specific absorption rate of 2.0 W kg{sup -1}, which is the restriction value of the International Electrotechnical Commission for the normal operating mode. As predicted, these values are below the temperature elevation of 1.5 deg. C that is expected to be teratogenic. However, these values exceeded the recommended temperature elevation limit of 0.5 deg. C by the International Commission on Non-Ionizing Radiation Protection. We also assessed the irradiation time required for a temperature elevation of 0.5 deg. C at the aforementioned specific absorption rate. As a result, the calculated irradiation time was 40 min.
Temperature elevation in the fetus from electromagnetic exposure during magnetic resonance imaging
International Nuclear Information System (INIS)
Kikuchi, Satoru; Ito, Koichi; Saito, Kazuyuki; Takahashi, Masaharu
2010-01-01
This study computationally assessed the temperature elevations due to electromagnetic wave energy deposition during magnetic resonance imaging in non-pregnant and pregnant woman models. We used a thermal model with thermoregulatory response of the human body for our calculations. We also considered the effect of blood temperature variation on body core temperature. In a thermal equilibrium state, the temperature elevations in the intrinsic tissues of the woman and fetal tissues were 0.85 and 0.61 deg. C, respectively, at a whole-body averaged specific absorption rate of 2.0 W kg -1 , which is the restriction value of the International Electrotechnical Commission for the normal operating mode. As predicted, these values are below the temperature elevation of 1.5 deg. C that is expected to be teratogenic. However, these values exceeded the recommended temperature elevation limit of 0.5 deg. C by the International Commission on Non-Ionizing Radiation Protection. We also assessed the irradiation time required for a temperature elevation of 0.5 deg. C at the aforementioned specific absorption rate. As a result, the calculated irradiation time was 40 min.
Ionospheric electron acceleration by electromagnetic waves near regions of plasma resonances
International Nuclear Information System (INIS)
Villalon, E.
1989-01-01
Electron acceleration by electromagnetic fields propagating in the inhomogeneous ionospheric plasma is investigated. It is found that high-amplitude short wavelength electrostatic waves are generated by the incident electromagnetic fields that penetrate the radio window. These waves can very efficiently transfer their energy to the electrons if the incident frequency is near the second harmonic of the cyclotron frequency
International Nuclear Information System (INIS)
Pophof, B.; Brix, G.
2017-01-01
During the last few years, new studies on biological effects of strong static magnetic fields and on thermal effects of high-frequency electromagnetic fields used in magnetic resonance imaging (MRI) were published. Many of these studies have not yet been included in the current safety recommendations. Scientific publications since 2010 on biological effects of static and electromagnetic fields in MRI were researched and evaluated. New studies confirm older publications that have already described effects of static magnetic fields on sensory organs and the central nervous system, accompanied by sensory perceptions. A new result is the direct effect of Lorentz forces on ionic currents in the semicircular canals of the vestibular system. Recent studies of thermal effects of high-frequency electromagnetic fields were focused on the development of anatomically realistic body models and a more precise simulation of exposure scenarios. Strong static magnetic fields can cause unpleasant sensations, in particular, vertigo. In addition, they can influence the performance of the medical staff and thus potentially endanger the patient's safety. As a precaution, medical personnel should move slowly within the field gradient. High-frequency electromagnetic fields lead to an increase in the temperature of patients' tissues and organs. This should be considered especially in patients with restricted thermoregulation and in pregnant women and neonates; in these cases exposure should be kept as low as possible. (orig.) [de
Calculation of rf fields in axisymmetric cavities
International Nuclear Information System (INIS)
Iwashita, Y.
1985-01-01
A new code, PISCES, has been developed for calculating a complete set of rf electromagnetic modes in an axisymmetric cavity. The finite-element method is used with up to third-order shape functions. Although two components are enough to express these modes, three components are used as unknown variables to take advantage of the symmetry of the element matrix. The unknowns are taken to be either the electric field components or the magnetic field components. The zero-divergence condition will be satisfied by the shape function within each element
Han, Sunwoo; Lee, Bong Jae
2016-01-25
In this work, we numerically investigate the electromagnetic resonances on two-dimensional tandem grating structures. The base of a tandem grating consists of an opaque Au substrate, a SiO(2) spacer, and a Au grating (concave type); that is, a well-known fishnet structure forming Au/SiO(2)/Au stack. A convex-type Au grating (i.e., topmost grating) is then attached on top of the base fishnet structure with or without additional SiO(2) spacer, resulting in two types of tandem grating structures. In order to calculate the spectral reflectance and local magnetic field distribution, the finite-difference time-domain method is employed. When the topmost Au grating is directly added onto the base fishnet structure, the surface plasmon and magnetic polariton in the base structure are branched out due to the geometric asymmetry with respect to the SiO(2) spacer. If additional SiO(2) spacer is added between the topmost Au grating and the base fishnet structure, new magnetic resonance modes appear due to coupling between two vertically aligned Au/SiO(2)/Au stacks. With the understanding of multiple electromagnetic resonance modes on the proposed tandem grating structures, we successfully design a broadband absorber made of Au and SiO(2) in the visible spectrum.
International Nuclear Information System (INIS)
Patel, M.D.
1978-01-01
The Einstein's field equations for an enveloping radiating zone surrounding rotating axisymmetric collapsing source are studied. The solution has singularity along the axis of rotation. It is proved that on null hyper surface u = 0, the solution of the field equation for the radiating zone match with solution of axially symmetric vacuum field equations obtained by the author. Landau Lifshitz complex is used to obtain conserved total mass. (author)
International Nuclear Information System (INIS)
Sugaya, Reija
1991-01-01
The velocity-space diffusion equation describing distortion of the velocity distribution function due to resonant wave-wave scattering of electromagnetic and electrostatic waves in an unmagnetized plasma is derived from the Vlasov-Maxwell equations by perturbation theory. The conservation laws for total energy and momentum densities of waves and particles are verified, and the time evolutions of the energy and momentum densities of particles are given in terms of the nonlinear wave-wave coupling coefficient in the kinetic wave equation. (author)
Ahmadizadeh, Y.; Jazi, B.; Abdoli-Arani, A.
2014-01-01
Response of a prolate spheroid plasma and/or an oblate spheroid plasma in presence of long wavelength electromagnetic wave has been studied. The resonance frequencies of these objects are obtained and it is found that they reduce to the resonance frequency of spherical cold plasma. Moreover, the resonant frequencies of prolate spheroid plasma and oblate spheroid plasma covered by a dielectric are investigated as well. Furthermore, their dependency on dielectric permittivity and geometry dimensions is simulated.
Electromagnetic design of a β=0.4 superconducting spoke resonator for a high intensity proton linac
International Nuclear Information System (INIS)
Pathak, Abhishek; Krishnagopal, Srinivas
2015-01-01
Here we present electromagnetic design simulations of a superconducting single-spoke resonator with a geometrical beta of 0.4 and operating at 325 MHz for a high intensity proton linac (HIPL). The spoke equatorial and base parameters were optimized to minimize the peak electric and peak magnetic fields and maximize the shunt impedance, while keeping the same resonant frequency. Variation of the surface magnetic fields was investigated as a function of the spoke base shape, and it was found that an elliptical profile is preferred over a circular or racecourse profile with E peak /E acc =4.71, E peak /E acc =4.33 (mT/(MV/m)) and R/Q=272 Ω. (author)
International Nuclear Information System (INIS)
Greentree, Andrew D.; Smith, T.B.; Echaniz, S.R. de; Durrant, A. V.; Marangos, J.P.; Segal, D.M.; Vaccaro, J.A.
2002-01-01
This paper presents a wide-ranging theoretical and experimental study of nonadiabatic transient phenomena in a Λ electromagnetically induced transparency system when a strong coupling field is rapidly switched on or off. The theoretical treatment uses a Laplace transform approach to solve the time-dependent density matrix equation. The experiments are carried out in a 87 Rb magneto-optical trap. The results show transient probe gain in parameter regions not previously studied, and provide insight into the transition dynamics between bare and dressed states
Resonant generation of electromagnetic surface wave by inhomogeneous relativistic electron stream
Energy Technology Data Exchange (ETDEWEB)
Cadez, V.M.; Vukovic, S. (Belgrade Univ. (Yugoslavia). Inst. za Fiziku); Frolov, V.V.; Kyrie, A.Y. (AN SSSR, Moscow. Fizicheskij Inst.)
1981-12-01
Generation of electromagnetic surface waves by relativistic inhomogeneous particle flows is investigated for plane and cylindrical geometries. The basic excitation mechanisms are shown to be the induced anomalous Doppler effect and the hydrodynamic Cerenkov effect. The relevant maximal growth rates may differ significantly from those derived for monoenergetic beams.
Resonant generation of electromagnetic surface wave by inhomogeneous relativistic electron stream
International Nuclear Information System (INIS)
Cadez, V.M.; Vukovic, S.; Frolov, V.V.; Kyrie, A.Y.
1981-01-01
Generation of electromagnetic surface waves by relativistic inhomogeneous particle flows is investigated for plane and cylindrical geometries. The basic excitation mechanisms are shown to be the induced anomalous Doppler effect and the hydrodynamic Cerenkov effect. The relevant maximal growth rates may differ significantly from those derived for monoenergetic beams. (author)
Axisymmetric control in tokamaks
International Nuclear Information System (INIS)
Humphreys, D.A.
1991-02-01
Vertically elongated tokamak plasmas are intrinsically susceptible to vertical axisymmetric instabilities as a result of the quadrupole field which must be applied to produce the elongation. The present work analyzes the axisymmetric control necessary to stabilize elongated equilibria, with special application to the Alcator C-MOD tokamak. A rigid current-conserving filamentary plasma model is applied to Alcator C-MOD stability analysis, and limitations of the model are addressed. A more physically accurate nonrigid plasma model is developed using a perturbed equilibrium approach to estimate linearized plasma response to conductor current variations. This model includes novel flux conservation and vacuum vessel stabilization effects. It is found that the nonrigid model predicts significantly higher growth rates than predicted by the rigid model applied to the same equilibria. The nonrigid model is then applied to active control system design. Multivariable pole placement techniques are used to determine performance optimized control laws. Formalisms are developed for implementing and improving nominal feedback laws using the C-MOD digital-analog hybrid control system architecture. A proportional-derivative output observer which does not require solution of the nonlinear Ricatti equation is developed to help accomplish this implementation. The nonrigid flux conserving perturbed equilibrium plasma model indicates that equilibria with separatrix elongation of at least κ sep = 1.85 can be stabilized robustly with the present control architecture and conductor/sensor configuration
On dynamics of resonant charged particles in cyclotron electromagnetic wave field
International Nuclear Information System (INIS)
Shyutte, N.M.; Izhovkina, N.I.
1989-01-01
The model of time and spatial separation of resonance and nonresonance particles with quasimonochromatic wave packets during their propagation in the magnetosphere is presented. In regions with elevated geomagnetic field gradients and.or in waveguide channels such separation can result in diffusion increase of resonance particles by the pitch angle and create ''little peaks'' in the distribution function tail
Energy Technology Data Exchange (ETDEWEB)
Elnaggar, Sameh Y. [School of Engineering and Information Technology, University of New South Wales, Canberra (Australia); Tervo, Richard J. [Department of Electrical and Computer Engineering, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada (Canada); Mattar, Saba M., E-mail: mattar@unb.ca [Chemistry Department, University of New Brunswick, Fredericton, NB, E3B 5A3 Canada (Canada)
2015-11-21
The theory and operation of various devices and systems, such as wireless power transfer via magnetic resonant coupling, magneto-inductive wave devices, magnetic resonance spectroscopy probes, and metamaterials can rely on coupled tuned resonators. The coupling strength is usually expressed in terms of the coupling coefficient κ, which can have electrical κ{sub E} and/or magnetic κ{sub M} components. In the current article, general expressions of κ are derived. The relation between the complex Poynting equation in its microscopic form and κ is made and discussed in detail. It is shown that κ can be expressed in terms of the interaction energy between the resonators' modes. It thus provides a general form that combines the magnetic and electric components of κ. The expressions make it possible to estimate the frequencies and fields of the coupled modes for arbitrarily oriented and spaced resonators. Thus, enabling the calculation of system specific parameters such as the transfer efficiency of wireless power transfer systems, resonator efficiency for electron spin resonance probes, and dispersion relations of magneto-inductive and stereo-metamaterials structures.
International Nuclear Information System (INIS)
Elnaggar, Sameh Y.; Tervo, Richard J.; Mattar, Saba M.
2015-01-01
The theory and operation of various devices and systems, such as wireless power transfer via magnetic resonant coupling, magneto-inductive wave devices, magnetic resonance spectroscopy probes, and metamaterials can rely on coupled tuned resonators. The coupling strength is usually expressed in terms of the coupling coefficient κ, which can have electrical κ E and/or magnetic κ M components. In the current article, general expressions of κ are derived. The relation between the complex Poynting equation in its microscopic form and κ is made and discussed in detail. It is shown that κ can be expressed in terms of the interaction energy between the resonators' modes. It thus provides a general form that combines the magnetic and electric components of κ. The expressions make it possible to estimate the frequencies and fields of the coupled modes for arbitrarily oriented and spaced resonators. Thus, enabling the calculation of system specific parameters such as the transfer efficiency of wireless power transfer systems, resonator efficiency for electron spin resonance probes, and dispersion relations of magneto-inductive and stereo-metamaterials structures
Basharov, A. M.
2018-03-01
The Markov model of spontaneous emission of an atom localized in a spatial region with a broadband electromagnetic field with zero photon density is considered in the conditions of coupling of the electromagnetic field with the broadband field of a neighboring space. The evolution operator of the system and the kinetic equation for the atom are obtained. It is shown that the field coupling constant affects the rate of spontaneous emission of the atom, but is not manifested in the atomic frequency shift. The analytic expression for the radiative decay constant for the atom is found to be analogous in a certain sense to the expression for the decay constant for a singly excited localized ensemble of identical atoms in the conditions when the effect of stabilization of its excited state by the Stark interaction with the vacuum broadband electromagnetic field is manifested. The model is formulated based on quantum stochastic differential equations of the non- Wiener type and the generalized algebra of the Ito differential of quantum random processes.
Axisymmetric tokamak scapeoff transport
International Nuclear Information System (INIS)
Singer, C.E.; Langer, W.D.
1982-08-01
We present the first self-consistent estimate of the magnitude of each term in a fluid treatment of plasma transport for a plasma lying in regions of open field lines in an axisymmetric tokamak. The fluid consists of a pure hydrogen plasma with sources which arise from its interaction with neutral hydrogen atoms. The analysis and results are limited to the high collisionality regime, which is optimal for a gaseous neutralizer divertor, or to a cold plasma mantle in a tokamak reactor. In this regime, both classical and neoclassical transport processes are important, and loss of particles and energy by diamagnetic flow are also significant. The prospect of extending the analysis to the lower collisionality regimes encountered in many existing experiments is discussed
Wang, Zhongxian; Liu, Yiping; Wei, Yonggeng; Song, Yilin
2018-01-01
The resonant coil design is taken as the core technology in the magnetic coupling resonant wireless power transmission system, which achieves energy transmission by the coupling of the resonant coil. This paper studies the effect of the resonant coil on energy transmission and the efficiency of the system. Combining a two-coil with a three-coil system, the optimum design method for the resonant coil is given to propose a novel coil structure. First, the co-simulation methods of Pspice and Maxwell are used. When the coupling coefficient of the resonant coil is different, the relationship between system transmission efficiency, output power, and frequency is analyzed. When the self-inductance of the resonant coil is different, the relationship between the performance and frequency of the system transmission is analyzed. Then, two-coil and three-coil structure models are built, and the parameters of the magnetic field of the coils are calculated and analyzed using the finite element method. In the end, a dual E-type simulation circuit model is used to optimize the design of the novel resonance coil. The co-simulation results show that the coupling coefficients of the two-coil, three-coil, and novel coil systems are 0.017, 0.17 and 0.0126, respectively. The power loss of the novel coil is 16.4 mW. There is an obvious improvement in the three-coil system, which shows that the magnetic leakage of the field and the energy coupling are relatively small. The new structure coil has better performance, and the load loss is lower; it can improve the system output power and transmission efficiency.
Electromagnetic Resonance in Biological Form: A Role for Fields in Morphogenesis
International Nuclear Information System (INIS)
Pietak, Alexis M
2011-01-01
In morphogenesis, the mechanisms through which homogeneous, symmetric collectives of self-same cells are able to consistently and precisely establish long-range pattern remain an open question of scientific research. This work explores the hypothesis of developing biological structures as dielectric microwave resonators, using plant leaves as a working example. A finite element analysis (FEA) model was designed to determine if suitable resonant modes were physically possible for geometric and electrical parameters similar to those of developing leaf tissue. Using the FEA model, resonant EM modes with patterns of relevance to developing leaf vein modalities were detected. Here I show how the single physical mechanism of EM resonance can self-consistently account for different kinds of key symmetry-breaking operations characteristic of a variety of leaf vascular patterns. On account of the existence of shared geometric signatures in a leaf's vascular pattern and the electric field component of EM resonant modes supported by a leaf-like structure, further theoretical and experimental investigations are warranted. Significantly, this hypothesis is not limited to leaf vascular patterning, but may be applicable to a variety of morphogenetic phenomena in a number of living systems.
Resonant excitation and the decay of autoionization states in a strong electromagnetic field
International Nuclear Information System (INIS)
Andryushin, A.I.; Kazakov, A.E.; Fedorov, M.V.
1985-01-01
Photoionization of atoms involving resonant excitation of the auto-ionization state is studied. The evolution of the total ionization probability, its dependence on the frequency of the resonance radiation and also the photoelectron energy spectrum are investigated. It is shown that the energy of the final state of the system may be localized either in the vicinity of E approximately Esub(α), where Esub(α) is the auto-ionization energy, or in the vicinity of E approximately Esub(α)+h/2πω where h/2πω is the quantum energy of the resonance radiation. The photoelectron specturum in the region E approximately Esub(α)+h/2πω as a whole is similar to the electron spectrum on photoionization of atoms involving resonance excitation of the bound state. A strong effect on the photoelectron spectrum in the region E approximately Esub(α) is exerted by interference of various decay channels of the ground state in the resonance field which leads to the appearance in the spectrum of a characteristic structure of the Fano type. Interence also affects the widths of the two spectral curves, the relatve amount of electrons in the two energy ranges and also other characteristics of the ionization process. It is shown that the presence of a noninterfering photoionization channel of the autoionization state ensures the finiteness of the swidths and heights of the spectral curves and the absence of complete ''coherency merging''
Production of gravitation waves by electromagnetic radiation
International Nuclear Information System (INIS)
Buchner, K.; Rosca, R.
1980-01-01
An exact solution of Einstein's equations is presented that corresponds to an axisymmetric bundle of electromagnetic waves with finite cross section. Outside this bundle, there is gravitational radiation parallel to the electromagnetic radiation. If no static electromagnetic fields are present, the frequency of the gravitational waves is twice the frequency of the electromagnetic waves. Einstein's energy complex vanishes identically. The covariant energy complex, however, yields also a radial momentum. (author)
Resonant e+e- production by time-varying electromagnetic field
International Nuclear Information System (INIS)
Farakos, K.; Koutsoumbas, G.; Tiktopoulos, G.
1990-01-01
As pointed out by Cornwall and Tiktopoulos (CT) strong, time-varying electric fields may produce e + e - pairs in a resonant fashion. This effect could be related to the sharp peaks in the e + e - spectrum observed in the GSI heavy-ion collision experiments. We attempt to go beyond the case of spatially uniform fields discussed by CT. We find that resonant e + e - production indeed takes place for electric fields derived from four-potentials of the form A 1 =A 2 =A 0 =0, A 3 =δ(t)b(x 3 ) provided by b(x) has discontinuities with a jump at least equal to π. (orig.)
International Nuclear Information System (INIS)
Vertij, A.A.; Gavrilov, S.P.; Shestopalov, V.P.
1990-01-01
Interaction of incident nuclear particle beam with J = 1/2 (neutrons) spin and (J = 1/2) protons with the target substance is considered. It is shown that neutron polarization at the target exit and neutron transparency (G) of the target depend significantly on incident wave amplitude level and physical parameter values which characterize the target, such as target temperature, resonator mirror reflection factor, number of spins interacting with the field, etc. Under interaction of neutrons with a target resonator which features a high mirror reflection factor and low losses for absorption which is not related to magnetic dipole absorption, a bistable response of neutron polarization and G manifests itself. 1 ref
Electromagnetic torques in the core and resonant excitation of decadal polar motion
Mound, Jon E.
2005-02-01
Motion of the rotation axis of the Earth contains decadal variations with amplitudes on the order of 10 mas. The origin of these decadal polar motions is unknown. A class of rotational normal modes of the core-mantle system termed torsional oscillations are known to affect the length of day (LOD) at decadal periods and have also been suggested as a possible excitation source for the observed decadal polar motion. Torsional oscillations involve relative motion between the outer core and the surrounding solid bodies, producing electromagnetic torques at the inner-core boundary (ICB) and core-mantle boundary (CMB). It has been proposed that the ICB torque can explain the excitation of the approximately 30-yr-period polar motion termed the Markowitz wobble. This paper uses the results of a torsional oscillation model to calculate the torques generated at Markowitz and other decadal periods and finds, in contrast to previous results, that electromagnetic torques at the ICB can not explain the observed polar motion.
Burlaka, Anatoly; Selyuk, Marina; Gafurov, Marat; Lukin, Sergei; Potaskalova, Viktoria; Sidorik, Evgeny
2014-05-01
To study the effects of electromagnetic radiation (EMR) of ultra high frequency (UHF) in the doses equivalent to the maximal permitted energy load for the staffs of the radar stations on the biochemical processes that occur in the cell organelles. Liver, cardiac and aorta tissues from the male rats exposed to non-thermal UHF EMR in pulsed and continuous modes were studied during 28 days after the irradiation by the electron paramagnetic resonance (EPR) methods including a spin trapping of superoxide radicals. The qualitative and quantitative disturbances in electron transport chain (ETC) of mitochondria are registered. A formation of the iron-nitrosyl complexes of nitric oxide (NO) radicals with the iron-sulphide (FeS) proteins, the decreased activity of FeS-protein N2 of NADH-ubiquinone oxidoreductase complex and flavo-ubisemiquinone growth combined with the increased rates of superoxide production are obtained. (i) Abnormalities in the mitochondrial ETC of liver and aorta cells are more pronounced for animals radiated in a pulsed mode; (ii) the alterations in the functioning of the mitochondrial ETC cause increase of superoxide radicals generation rate in all samples, formation of cellular hypoxia, and intensification of the oxide-initiated metabolic changes; and (iii) electron paramagnetic resonance methods could be used to track the qualitative and quantitative changes in the mitochondrial ETC caused by the UHF EMR.
International Nuclear Information System (INIS)
Bhattacharyya, B.; Chakraborty, B.
1979-01-01
Nonlinear corrections of a left and a right circularly polarized electromagnetic wave of the same frequency, propagating in the direction of a static and uniform magnetic field in a cold and collisionally damped two-component plasma, have been evaluated. The nonlinearly correct dispersion relation, self-generating nonlinear precessional rotation of the polarization ellipse of the wave and the shift in a wave parameter depend on linear combinations of products of the amplitude components taken two at a time and hence on the energies of the waves. Both in the low frequency resonance (that is when the ion cyclotron frequency equals the wave frequency) and in the high frequency resonance (that is when the electron cyclotron frequency equals the wave frequency), the self-precessional rate and wavenumber shift are found to be large and so have the possibility of detection in laboratory experiments. Moreover, for the limit leading to Alfven waves, these nonlinear effects have been found to have some interesting and significant properties. (Auth.)
Yeung, Sai Ho; Pradhan, Raunaq; Feng, Xiaohua; Zheng, Yuanjin
2015-09-01
Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF) stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC) stimulation, magnetic stimulation (MS) and transcutaneous electrical nerve stimulation (TENS) are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissue voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.
Directory of Open Access Journals (Sweden)
Sai Ho Yeung
2015-09-01
Full Text Available Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC stimulation, magnetic stimulation (MS and transcutaneous electrical nerve stimulation (TENS are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissue voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.
Energy Technology Data Exchange (ETDEWEB)
Yeung, Sai Ho; Pradhan, Raunaq; Feng, Xiaohua; Zheng, Yuanjin [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)
2015-09-15
Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF) stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC) stimulation, magnetic stimulation (MS) and transcutaneous electrical nerve stimulation (TENS) are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissue voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.
Resonant circuit which provides dual frequency excitation for rapid cycling of an electromagnet
Praeg, Walter F.
1984-01-01
Disclosed is a ring magnet control circuit that permits synchrotron repetition rates much higher than the frequency of the cosinusoidal guide field of the ring magnet during particle acceleration. the control circuit generates cosinusoidal excitation currents of different frequencies in the half waves. During radio frequency acceleration of the particles in the synchrotron, the control circuit operates with a lower frequency cosine wave and thereafter the electromagnets are reset with a higher frequency half cosine wave. Flat-bottom and flat-top wave shaping circuits maintain the magnetic guide field in a relatively time-invariant mode during times when the particles are being injected into the ring magnets and when the particles are being ejected from the ring magnets.
Axisymmetric annular curtain stability
International Nuclear Information System (INIS)
Ahmed, Zahir U; Khayat, Roger E; Maissa, Philippe; Mathis, Christian
2012-01-01
A temporal stability analysis was carried out to investigate the stability of an axially moving viscous annular liquid jet subject to axisymmetric disturbances in surrounding co-flowing viscous gas media. We investigated in this study the effects of inertia, surface tension, the gas-to-liquid density ratio, the inner-to-outer radius ratio and the gas-to-liquid viscosity ratio on the stability of the jet. With an increase in inertia, the growth rate of the unstable disturbances is found to increase. The dominant (or most unstable) wavenumber decreases with increasing Reynolds number for larger values of the gas-to-liquid viscosity ratio. However, an opposite tendency for the most unstable wavenumber is predicted for small viscosity ratio in the same inertia range. The surrounding gas density, in the presence of viscosity, always reduces the growth rate, hence stabilizing the flow. There exists a critical value of the density ratio above which the flow becomes stable for very small viscosity ratio, whereas for large viscosity ratio, no stable flow appears in the same range of the density ratio. The curvature has a significant destabilizing effect on the thin annular jet, whereas for a relatively thick jet, the maximum growth rate decreases as the inner radius increases, irrespective of the surrounding gas viscosity. The degree of instability increases with Weber number for a relatively large viscosity ratio. In contrast, for small viscosity ratio, the growth rate exhibits a dramatic dependence on the surface tension. There is a small Weber number range, which depends on the viscosity ratio, where the flow is stable. The viscosity ratio always stabilizes the flow. However, the dominant wavenumber increases with increasing viscosity ratio. The range of unstable wavenumbers is affected only by the curvature effect. (paper)
Energy Technology Data Exchange (ETDEWEB)
Evangelou, Sofia, E-mail: Evangelousof@gmail.com
2017-05-10
Highlights: • A high-Q single-crystal diamond nanomechanical resonator embedded with nitrogen-vacancy (NV) centers is studied. • A Δ-type coupling configuration is formed. • The spin states of the ground state triplet of the NV centers interact with a strain field and two microwave fields. • The absorption and dispersion properties of the acoustic wave field are controlled by the use of the relative phase of the fields. • Phase-dependent acoustic wave absorption, transparency, and gain are obtained. • “Slow sound” and negative group velocities are also possible. - Abstract: We consider a high-Q single-crystal diamond nanomechanical resonator embedded with nitrogen-vacancy (NV) centers. We study the interaction of the transitions of the spin states of the ground state triplet of the NV centers with a strain field and two microwave fields in a Δ-type coupling configuration. We use the relative phase of the fields for the control of the absorption and dispersion properties of the acoustic wave field. Specifically, we show that by changing the relative phase of the fields, the acoustic field may exhibit absorption, transparency, gain and very interesting dispersive properties.
Fadel, M A; Mohamed, S A; Abdelbacki, A M; El-Sharkawy, A H
2014-08-01
Typhoid is a serious disease difficult to be treated with conventional drugs. The aim of this study was to demonstrate a new method for the control of Salmonella typhi growth, through the interference with the bioelectric signals generated from the microbe during cell division by extremely low frequency electromagnetic waves (ELF-EMW-ELF-EM) at resonance frequency. Isolated Salmonella typhi was subjected to square amplitude modulated waves (QAMW) with different modulation frequencies from two generators with constant carrier frequency of 10 MHz, amplitude of 10 Vpp, modulating depth ± 2 Vpp and constant field strength of 200 V m(-1) at 37°C. Both the control and exposed samples were incubated at the same conditions during the experiment. The results showed that there was highly significant inhibition effect for Salm. typhi exposed to 0·8 Hz QAMW for a single exposure for 75 min. Dielectric relaxation, TEM and DNA results indicated highly significant changes in the molecular structure of the DNA and cellular membrane resulting from the exposure to the inhibiting EM waves. It was concluded that finding out the inhibiting resonance frequency of ELF-EM waves that deteriorates Salm. typhi growth will be promising method for the treatment of Salm. typhi infection either in vivo or in vitro. This new non-invasive technique for treatment of bacterial infections is of considerable interest for the use in medical and biotechnological applications. © 2014 The Society for Applied Microbiology.
Potential formation in axisymmetrized tandem mirror GAMMA 10
International Nuclear Information System (INIS)
Cho, T.; Ichimura, M.; Inutake, M.
1985-01-01
The paper reports experimental results on potential formation and end plugging in the axisymmetrized tandem mirror GAMMA 10. The plugging at both ends has been achieved by a combination of neutral beams and gyrotrons. The presence of a plug potential with a thermal barrier in an axisymmetric mirror has been confirmed by direct measurement of the axial potential profile. Enhancement of axial particle confinement has been observed during the end plugging. Non-ambipolar radial transport has been greatly reduced in the axisymmetrized magnetic configuration. The potentials measured by beam probes and end loss analysers are 0.7, 0.4 and 1.1 kV in the central, barrier and plug regions, respectively. Strong end plugging is observed when the central-cell density is higher than the densities in the plug and the barrier, and the plug density remains higher than the barrier density. The plug electron temperature is higher than the central temperature. Hot electrons forming a football-shaped profile have been stably produced in the axisymmetric mirror. The beta value and the fraction of the hot electrons reach up to 5% and 0.8, respectively. Central-cell ion-cyclotron resonance heating can sustain a stable plasma with higher density and ion temperature when resonance surfaces exist in both the anchor and the central cells. (author)
Alobaidi, Wissam M.; Nima, Zeid A.; Sandgren, Eric
2018-01-01
Localised surface plasmon (LSP)-like resonance phenomena were simulated in COMSOL Multiphysics™, and the electric field enhancement was evaluated in eight pipe defects using the microwave band from 1.80 to 3.00 GHz and analysed by finite element analysis (FEA). The simulation was carried out, in each defect case, on a pipe that has 762 mm length and 152.4 mm inner diameter, and 12.7 mm pipe wall thickness. Defects were positioned in the middle of the pipe and were named as follows; SD: Square Defect, FCD: fillet corner defect, FD: fillet defect, HCD: half circle defect, TCD: triangle corner defect, TD: triangle defect, ZD: zigzag defect, GD: gear defect. The LSP electric field, and scattering parametric (S21, and S11) waves were evaluated in all cases and found to be strongly dependent on the size and the shape of the defect rather than the pipe and or the medium materials.
Dogan, M; Turtay, M G; Oguzturk, H; Samdanci, E; Turkoz, Y; Tasdemir, S; Alkan, A; Bakir, S
2012-06-01
The effects of electromagnetic radiation (EMR) produced by a third-generation (3G) mobile phone (MP) on rat brain tissues were investigated in terms of magnetic resonance spectroscopy (MRS), biochemistry, and histopathological evaluations. The rats were randomly assigned to two groups: Group 1 is composed of 3G-EMR-exposed rats (n = 9) and Group 2 is the control group (n = 9). The first group was subjected to EMR for 20 days. The control group was not exposed to EMR. Choline (Cho), creatinin (Cr), and N-acetylaspartate (NAA) levels were evaluated by MRS. Catalase (CAT) and glutathione peroxidase (GSH-Px) enzyme activities were measured by spectrophotometric method. Histopathological analyses were carried out to evaluate apoptosis in the brain tissues of both groups. In MRS, NAA/Cr, Cho/Cr, and NAA/Cho ratios were not significantly different between Groups 1 and 2. Neither the oxidative stress parameters, CAT and GSH-Px, nor the number of apoptotic cells were significantly different between Groups 1 and 2. Usage of short-term 3G MP does not seem to have a harmful effect on rat brain tissue.
CLASSIFICATION OF STELLAR ORBITS IN AXISYMMETRIC GALAXIES
Energy Technology Data Exchange (ETDEWEB)
Li, Baile; Holley-Bockelmann, Kelly [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Khan, Fazeel Mahmood, E-mail: baile.li@vanderbilt.edu, E-mail: k.holley@vanderbilt.edu, E-mail: khanfazeel.ist@gmail.com [Department of Space Science, Institute of Space Technology, P.O. Box 2750 Islamabad (Pakistan)
2015-09-20
It is known that two supermassive black holes (SMBHs) cannot merge in a spherical galaxy within a Hubble time; an emerging picture is that galaxy geometry, rotation, and large potential perturbations may usher the SMBH binary through the critical three-body scattering phase and ultimately drive the SMBH to coalesce. We explore the orbital content within an N-body model of a mildly flattened, non-rotating, SMBH-embedded elliptical galaxy. When used as the foundation for a study on the SMBH binary coalescence, the black holes bypassed the binary stalling often seen within spherical galaxies and merged on gigayear timescales. Using both frequency-mapping and angular momentum criteria, we identify a wealth of resonant orbits in the axisymmetric model, including saucers, that are absent from an otherwise identical spherical system and that can potentially interact with the binary. We quantified the set of orbits that could be scattered by the SMBH binary, and found that the axisymmetric model contained nearly six times the number of these potential loss cone orbits compared to our equivalent spherical model. In this flattened model, the mass of these orbits is more than three times that of the SMBH, which is consistent with what the SMBH binary needs to scatter to transition into the gravitational wave regime.
International Nuclear Information System (INIS)
Katayama, I.; Fujita, Y.; Fujiwara, M.; Morinobu, S.; Ikegami, H.
1978-01-01
A lens type pair spectrometer of electron and positron has been developed and tested in order to detect the electromagnetic decay (pair creation) of the E0 giant resonance state. It was found from the one day machine time test (targets: natural Mo and Pb, beam:α, 70 MeV) that the improvement of the apparatus is necessary for getting a definite information on the yield of high energy electron pairs. (author)
Chubb, Scott
2007-03-01
Only recently (talk by P.A. Mosier-Boss et al, in this session) has it become possible to trigger high energy particle emission and Excess Heat, on demand, in LENR involving PdD. Also, most nuclear physicists are bothered by the fact that the dominant reaction appears to be related to the least common deuteron(d) fusion reaction,d+d ->α+γ. A clear consensus about the underlying effect has also been illusive. One reason for this involves confusion about the approximate (SU2) symmetry: The fact that all d-d fusion reactions conserve isospin has been widely assumed to mean the dynamics is driven by the strong force interaction (SFI), NOT EMI. Thus, most nuclear physicists assume: 1. EMI is static; 2. Dominant reactions have smallest changes in incident kinetic energy (T); and (because of 2), d+d ->α+γ is suppressed. But this assumes a stronger form of SU2 symmetry than is present; d+d ->α+γ reactions are suppressed not because of large changes in T but because the interaction potential involves EMI, is dynamic (not static), the SFI is static, and because the two incident deuterons must have approximate Bose Exchange symmetry and vanishing spin. A generalization of this idea involves a resonant form of reaction, similar to the de-excitation of an atom. These and related (broken gauge) symmetry EMI effects on LENR are discussed.
International Nuclear Information System (INIS)
Winter, Lukas; Oezerdem, Celal; Hoffmann, Werner; Lindt, Tessa van de; Periquito, Joao; Ji, Yiyi; Ghadjar, Pirus; Budach, Volker; Wust, Peter; Niendorf, Thoralf
2015-01-01
Glioblastoma multiforme is the most common and most aggressive malign brain tumor. The 5-year survival rate after tumor resection and adjuvant chemoradiation is only 10 %, with almost all recurrences occurring in the initially treated site. Attempts to improve local control using a higher radiation dose were not successful so that alternative additive treatments are urgently needed. Given the strong rationale for hyperthermia as part of a multimodal treatment for patients with glioblastoma, non-invasive radio frequency (RF) hyperthermia might significantly improve treatment results. A non-invasive applicator was constructed utilizing the magnetic resonance (MR) spin excitation frequency for controlled RF hyperthermia and MR imaging in an integrated system, which we refer to as thermal MR. Applicator designs at RF frequencies 300 MHz, 500 MHz and 1GHz were investigated and examined for absolute applicable thermal dose and temperature hotspot size. Electromagnetic field (EMF) and temperature simulations were performed in human voxel models. RF heating experiments were conducted at 300 MHz and 500 MHz to characterize the applicator performance and validate the simulations. The feasibility of thermal MR was demonstrated at 7.0 T. The temperature could be increased by ~11 °C in 3 min in the center of a head sized phantom. Modification of the RF phases allowed steering of a temperature hotspot to a deliberately selected location. RF heating was monitored using the integrated system for MR thermometry and high spatial resolution MRI. EMF and thermal simulations demonstrated that local RF hyperthermia using the integrated system is feasible to reach a maximum temperature in the center of the human brain of 46.8 °C after 3 min of RF heating while surface temperatures stayed below 41 °C. Using higher RF frequencies reduces the size of the temperature hotspot significantly. The opportunities and capabilities of thermal magnetic resonance for RF hyperthermia interventions
Winter, Lukas; Oezerdem, Celal; Hoffmann, Werner; van de Lindt, Tessa; Periquito, Joao; Ji, Yiyi; Ghadjar, Pirus; Budach, Volker; Wust, Peter; Niendorf, Thoralf
2015-09-22
Glioblastoma multiforme is the most common and most aggressive malign brain tumor. The 5-year survival rate after tumor resection and adjuvant chemoradiation is only 10 %, with almost all recurrences occurring in the initially treated site. Attempts to improve local control using a higher radiation dose were not successful so that alternative additive treatments are urgently needed. Given the strong rationale for hyperthermia as part of a multimodal treatment for patients with glioblastoma, non-invasive radio frequency (RF) hyperthermia might significantly improve treatment results. A non-invasive applicator was constructed utilizing the magnetic resonance (MR) spin excitation frequency for controlled RF hyperthermia and MR imaging in an integrated system, which we refer to as thermal MR. Applicator designs at RF frequencies 300 MHz, 500 MHz and 1GHz were investigated and examined for absolute applicable thermal dose and temperature hotspot size. Electromagnetic field (EMF) and temperature simulations were performed in human voxel models. RF heating experiments were conducted at 300 MHz and 500 MHz to characterize the applicator performance and validate the simulations. The feasibility of thermal MR was demonstrated at 7.0 T. The temperature could be increased by ~11 °C in 3 min in the center of a head sized phantom. Modification of the RF phases allowed steering of a temperature hotspot to a deliberately selected location. RF heating was monitored using the integrated system for MR thermometry and high spatial resolution MRI. EMF and thermal simulations demonstrated that local RF hyperthermia using the integrated system is feasible to reach a maximum temperature in the center of the human brain of 46.8 °C after 3 min of RF heating while surface temperatures stayed below 41 °C. Using higher RF frequencies reduces the size of the temperature hotspot significantly. The opportunities and capabilities of thermal magnetic resonance for RF hyperthermia
Electromagnetic Fields in Reverberant Environments
Vogt-Ardatjew, Robert Andrzej
2017-01-01
The phenomenon of resonating electromagnetic (EM) fields has been commonly and successfully exploited in reverberation chambers (RC) for the purpose of electromagnetic compatibility (EMC) testing, as well as modeling multipath environments. Although largely successful, the currently used statistical
International Nuclear Information System (INIS)
Yang Bao-Dong; Gao Jing; Liang Qiang-Bing; Wang Jie; Zhang Tian-Cai; Wang Jun-Min
2011-01-01
In a Doppler-broadened ladder-type cesium atomic system (6S 1/2 -6P 3/2 -8S 1/2 ), this paper characterizes electromagnetically induced transparency (EIT) in two different experimental arrangements, and investigates the influence of the double-resonance optical-pumping (DROP) effect on EIT in both arrangements. When the probe laser is weak, DROP is explicitly suppressed. When the probe laser is moderate, population of the intermediate level (6P 3/2 F' = 5) is remarkable, therefore DROP is mixed with EIT. An interesting bimodal spectrum with the broad component due to DROP and the narrow part due to EIT has been clearly observed in cesium 6S 1/2 F = 4−6P 3/2 F' = 5−8S 1/2 F″ = 4 transitions. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
On the axisymmetric Lewis metric
International Nuclear Information System (INIS)
Gariel, J.; Marcilhacy, G.
2001-03-01
We obtain the general solution of the axisymmetric stationary vacuum spacetime of Lewis. After precising the fundamental hypothesis of Lewis, we demonstrate that the solution is related to an arbitrary harmonic function. Formally, these solutions are the same as for the corresponding cylindrically symmetric case, and can be classified in a similar way. Furthermore, the interpretation, in the cylindrically symmetric system, of the field equations as decribing the motion of a classical particle in a central force field is still valid. (author)
Seismic analysis of axisymmetric shells
International Nuclear Information System (INIS)
Jospin, R.J.; Toledo, E.M.; Feijoo, R.A.
1984-01-01
Axisymmetric shells subjected to multiple support excitation are studied. The shells are spatialy discretized by the finite element method and in order to obtain estimates for the maximum values of displacements and stresses the response spectrum tecnique is used. Finally, some numerical results are presented and discussed in the case of a shell of revolution with vertical symmetry axis, subjected to seismic ground motions in the horizontal, vertical and rocking directions. (Author) [pt
Bernard, J.
2012-12-01
The Manufacturers of geophysical instruments have been facing these past decades the fast evolution of the electronics and of the computer sciences. More automatisms have been introduced into the equipment and into the processing and interpretation software which may let believe that conducting geophysical surveys requires less understanding of the method and less experience than in the past. Hence some misunderstandings in the skills that are needed to make the geophysical results well integrated among the global information which the applied geologist needs to acquire to be successful in his applications. Globally, the demand in geophysical investigation goes towards more penetration depth, requiring more powerful transmitters, and towards a better resolution, requiring more data such as in 3D analysis. Budgets aspects strongly suggest a high efficiency in the field associated to high speed data processing. The innovation is required in all aspects of geophysics to fit with the market needs, including new technological (instruments, software) and methodological (methods, procedures, arrays) developments. The structures in charge of the geophysical work can be public organisations (institutes, ministries, geological surveys,…) or can come from the private sector (large companies, sub-contractors, consultants, …), each one of them getting their own constraints in the field work and in the processing and interpretation phases. In the applications concerning Groundwater investigations, Mining Exploration, Environmental and Engineering surveys, examples of data and their interpretation presently carried out all around the world will be presented for DC Resistivity (Vertical Electrical Sounding, 2D, 3D Resistivity Imaging, Resistivity Monitoring), Induced Polarisation (Time Domain 2D, 3D arrays for mining and environmental), Magnetic Resonance Sounding (direct detection and characterisation of groundwater) and Electromagnetic (multi-component and multi
Zao, Yongming; Ouyang, Qi; Chen, Jiawei; Zhang, Xinglan; Hou, Shuaicheng
2017-08-01
This paper investigates the design and implementation of an improved series-parallel inductor-capacitor-inductor (LsCpLp) resonant circuit power supply for excitation of electromagnetic acoustic transducers (EMATs). The main advantage of the proposed resonant circuit is the absence of a high-permeability dynamic transformer. A high-frequency pulsating voltage gain can be achieved through a double resonance phenomenon. Both resonant tailing behavior and higher harmonics are suppressed by the improved resonant circuit, which also contributes to the generation of ultrasonic waves. Additionally, the proposed circuit can realize impedance matching and can also optimize the transduction efficiency. The complete design and implementation procedure for the power supply is described and has been validated by implementation of the proposed power supply to drive a portable EMAT. The circuit simulation results show close agreement with the experimental results and thus confirm the validity of the proposed topology. The proposed circuit is suitable for use as a portable EMAT excitation power supply that is fed by a low-voltage source.
Zao, Yongming; Ouyang, Qi; Chen, Jiawei; Zhang, Xinglan; Hou, Shuaicheng
2017-08-01
This paper investigates the design and implementation of an improved series-parallel inductor-capacitor-inductor (L s C p L p ) resonant circuit power supply for excitation of electromagnetic acoustic transducers (EMATs). The main advantage of the proposed resonant circuit is the absence of a high-permeability dynamic transformer. A high-frequency pulsating voltage gain can be achieved through a double resonance phenomenon. Both resonant tailing behavior and higher harmonics are suppressed by the improved resonant circuit, which also contributes to the generation of ultrasonic waves. Additionally, the proposed circuit can realize impedance matching and can also optimize the transduction efficiency. The complete design and implementation procedure for the power supply is described and has been validated by implementation of the proposed power supply to drive a portable EMAT. The circuit simulation results show close agreement with the experimental results and thus confirm the validity of the proposed topology. The proposed circuit is suitable for use as a portable EMAT excitation power supply that is fed by a low-voltage source.
Stationary axisymmetric Einstein--Maxwell field equations
International Nuclear Information System (INIS)
Catenacci, R.; Diaz Alonso, J.
1976-01-01
We show the existence of a formal identity between Einstein's and Ernst's stationary axisymmetric gravitational field equations and the Einstein--Maxwell and the Ernst equations for the electrostatic and magnetostatic axisymmetric cases. Our equations are invariant under very simple internal symmetry groups, and one of them appears to be new. We also obtain a method for associating two stationary axisymmetric vacuum solutions with every electrostatic known
Dispersion equations for field-aligned cyclotron waves in axisymmetric magnetospheric plasmas
Directory of Open Access Journals (Sweden)
N. I. Grishanov
2006-03-01
Full Text Available In this paper, we derive the dispersion equations for field-aligned cyclotron waves in two-dimensional (2-D magnetospheric plasmas with anisotropic temperature. Two magnetic field configurations are considered with dipole and circular magnetic field lines. The main contribution of the trapped particles to the transverse dielectric permittivity is estimated by solving the linearized Vlasov equation for their perturbed distribution functions, accounting for the cyclotron and bounce resonances, neglecting the drift effects, and assuming the weak connection of the left-hand and right-hand polarized waves. Both the bi-Maxwellian and bi-Lorentzian distribution functions are considered to model the ring current ions and electrons in the dipole magnetosphere. A numerical code has been developed to analyze the dispersion characteristics of electromagnetic ion-cyclotron waves in an electron-proton magnetospheric plasma with circular magnetic field lines, assuming that the steady-state distribution function of the energetic protons is bi-Maxwellian. As in the uniform magnetic field case, the growth rate of the proton-cyclotron instability (PCI in the 2-D magnetospheric plasmas is defined by the contribution of the energetic ions/protons to the imaginary part of the transverse permittivity elements. We demonstrate that the PCI growth rate in the 2-D axisymmetric plasmasphere can be significantly smaller than that for the straight magnetic field case with the same macroscopic bulk parameters.
International Nuclear Information System (INIS)
Skoblin, A.A.
1994-01-01
Free nonrelativistic electrons in both a static magnetic field and an electromagnetic wave are considered. A plane-polarized wave propagates along a magnetic field, its frequency is close to the electron rotation frequency in a magnetic field. Electron spin is taken into account. An electron quasi energy spectrum and steady states (quasi energy states) are constructed. 6 refs
Directory of Open Access Journals (Sweden)
A. G. Yahnin
2003-03-01
Full Text Available Continuous observations of fluctuations of the geomagnetic field at Sodankylä Geophysical Observatory (L = 5.2 were used for a comprehensive morphological study of the spectral resonance structure (SRS seen in the background electromagnetic noise in the frequency range of 0.1–4.0 Hz. It is shown that the occurrence rate of SRS is higher in the nighttime than in the daytime. The occurrence rate is higher in winter than in summer. The SRS frequencies and the difference between neighbouring eigenfrequencies (the frequency scale increase towards nighttime and decrease towards daytime. Both frequency scale and occurrence rate exhibit a clear tendency to decrease from minimum to maximum of the solar activity cycle. It is found that the occurrence rate of SRS decreases when geomagnetic activity increases. The SRS is believed to be a consequence of a resonator for Alfvén waves, which is suggested to exist in the upper ionosphere. According to the theory of the ionospheric Alfvén resonator (IAR, characteristics of SRS crucially depend on electron density in the F-layer maximum, as well as on the altitudinal scale of the density decay above the maximum.We compared the SRS morphological properties with predictions of the IAR theory. The ionospheric parameters needed for calculation were obtained from the ionosphere model (IRI-95, as well as from measurements made with the ionosonde in Sodankylä. We conclude that, indeed, the main morphological properties of SRS are explained on the basis of the IAR theory. The measured parameters of SRS can be used for improving the ionospheric models.Key words. Ionosphere (auroral ionosphere; wave propagation – Radio Science (electromagnetic noise and interference
Analytic modeling of axisymmetric disruption halo currents
International Nuclear Information System (INIS)
Humphreys, D.A.; Kellman, A.G.
1999-01-01
Currents which can flow in plasma facing components during disruptions pose a challenge to the design of next generation tokamaks. Induced toroidal eddy currents and both induced and conducted poloidal ''halo'' currents can produce design-limiting electromagnetic loads. While induction of toroidal and poloidal currents in passive structures is a well-understood phenomenon, the driving terms and scalings for poloidal currents flowing on open field lines during disruptions are less well established. A model of halo current evolution is presented in which the current is induced in the halo by decay of the plasma current and change in enclosed toroidal flux while being convected into the halo from the core by plasma motion. Fundamental physical processes and scalings are described in a simplified analytic version of the model. The peak axisymmetric halo current is found to depend on halo and core plasma characteristics during the current quench, including machine and plasma dimensions, resistivities, safety factor, and vertical stability growth rate. Two extreme regimes in poloidal halo current amplitude are identified depending on the minimum halo safety factor reached during the disruption. A 'type I' disruption is characterized by a minimum safety factor that remains relatively high (typically 2 - 3, comparable to the predisruption safety factor), and a relatively low poloidal halo current. A 'type II' disruption is characterized by a minimum safety factor comparable to unity and a relatively high poloidal halo current. Model predictions for these two regimes are found to agree well with halo current measurements from vertical displacement event disruptions in DIII-D [T. S. Taylor, K. H. Burrell, D. R. Baker, G. L. Jackson, R. J. La Haye, M. A. Mahdavi, R. Prater, T. C. Simonen, and A. D. Turnbull, open-quotes Results from the DIII-D Scientific Research Program,close quotes in Proceedings of the 17th IAEA Fusion Energy Conference, Yokohama, 1998, to be published in
Streamline topology of axisymmetric flows
DEFF Research Database (Denmark)
Brøns, Morten
Topological fluid mechanics in the sense of the present paper is the study and classification of flow patterns close to a critical point. Here we discuss the topology of steady viscous incompressible axisymmetric flows in the vicinity of the axis. Following previous studies the velocity field $v...... to the authors knowledge has not been used systematically to high orders in topological fluid mechanics. We compare the general results with experimental and computational results on the Vogel-Ronneberg flow. We show that the topology changes observed when recirculating bubbles on the vortex axis are created...... and interact follow the topological classification and that the complete set of patterns found is contained in a codimension-4 unfolding of the most simple singular configuration....
CRUCIB: an axisymmetric convection code
International Nuclear Information System (INIS)
Bertram, L.A.
1975-03-01
The CRUCIB code was written in support of an experimental program aimed at measurement of thermal diffusivities of refractory liquids. Precise values of diffusivity are necessary to realistic analysis of reactor safety problems, nuclear waste disposal procedures, and fundamental metal forming processes. The code calculates the axisymmetric transient convective motions produced in a right circular cylindrical crucible, which is surface heated by an annular heat pulse. Emphasis of this report is placed on the input-output options of the CRUCIB code, which are tailored to assess the importance of the convective heat transfer in determining the surface temperature distribution. Use is limited to Prandtl numbers less than unity; larger values can be accommodated by replacement of a single block of the code, if desired. (U.S.)
An axisymmetric gravitational collapse code
Energy Technology Data Exchange (ETDEWEB)
Choptuik, Matthew W [CIAR Cosmology and Gravity Program, Department of Physics and Astronomy, University of British Columbia, Vancouver BC, V6T 1Z1 (Canada); Hirschmann, Eric W [Department of Physics and Astronomy, Brigham Young University, Provo, UT 84604 (United States); Liebling, Steven L [Southampton College, Long Island University, Southampton, NY 11968 (United States); Pretorius, Frans [Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
2003-05-07
We present a new numerical code designed to solve the Einstein field equations for axisymmetric spacetimes. The long-term goal of this project is to construct a code that will be capable of studying many problems of interest in axisymmetry, including gravitational collapse, critical phenomena, investigations of cosmic censorship and head-on black-hole collisions. Our objective here is to detail the (2+1)+1 formalism we use to arrive at the corresponding system of equations and the numerical methods we use to solve them. We are able to obtain stable evolution, despite the singular nature of the coordinate system on the axis, by enforcing appropriate regularity conditions on all variables and by adding numerical dissipation to hyperbolic equations.
An axisymmetric gravitational collapse code
International Nuclear Information System (INIS)
Choptuik, Matthew W; Hirschmann, Eric W; Liebling, Steven L; Pretorius, Frans
2003-01-01
We present a new numerical code designed to solve the Einstein field equations for axisymmetric spacetimes. The long-term goal of this project is to construct a code that will be capable of studying many problems of interest in axisymmetry, including gravitational collapse, critical phenomena, investigations of cosmic censorship and head-on black-hole collisions. Our objective here is to detail the (2+1)+1 formalism we use to arrive at the corresponding system of equations and the numerical methods we use to solve them. We are able to obtain stable evolution, despite the singular nature of the coordinate system on the axis, by enforcing appropriate regularity conditions on all variables and by adding numerical dissipation to hyperbolic equations
Directory of Open Access Journals (Sweden)
C. Subaar
2017-07-01
Full Text Available Magnetic resonance imaging current operating frequencies are above 100 kHz which is converted to heat through resistive tissue losses during imaging. The imaging is coupled with a concurring increase in temperature in patients. Magnetic resonance imaging of the brain has seen a rising clinical request during diagnosis and therefore become imperative that its safety issues be assessed. This study modelled Pennes' classical bio-heat equation using Finite Difference Method (FDM approach and with the help of MATLAB programming language, predicted three dimensional steady state temperature distributions in patients during magnetic resonance imaging. Sixty-four paediatric patients' referred for (head brain magnetic resonance imaging scan at 37 Military Hospital and the Diagnostic Center Limited, Ghana, pre-scan and post-scan temperatures were measured at the right tympanic. The numerically steady state temperature distribution during magnetic resonance imaging shows that there is excessive temperature elevation at the skin surface of the patients. The resulting skin heating during magnetic resonance imaging can reach dangerous level which suggests that the ohmic heating of tissue is greatest at the surface and minimal at the center of the patient's brain. Though the experimental results show that patients brain temperature increase after imaging, all measured temperatures were within acceptable safe levels.
DEFF Research Database (Denmark)
Petersen, Nils Holger
2014-01-01
A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice.......A chapter in a book about terminology within the field of medievalism: the chapter discusses the resonance of medieval music and ritual in modern (classical) music culture and liturgical practice....
Numerical solutions of ICRF fields in axisymmetric mirrors
International Nuclear Information System (INIS)
Phillips, M.W.
1985-01-01
The results of a new numerical code called GARFIELD (Grumman Aerospace Rf Field code) that calculates ICRF Fields in axisymmetric mirror geometry (such as the central cell of a tandem mirror or an RF test stand) are presented. The code solves the electromagnetic wave equation using a cold plasma dispersion relation with a small collision frequency to simulate absorption. The purpose of the calculation is to examine how ICRF wave structure and propagation is effected by the axial variation of the magnetic field in a mirror for various antenna designs. In the code the wave equation is solved in flux coordinates using a finite element method. This should allow more complex dielectric tensors to be modeled in the future. The resulting matrix is solved iteratively, to maximize the allowable size of the spatial grid. Results for a typical antenna array in a simple mirror will be shown
The numerical solution of ICRF fields in axisymmetric mirrors
International Nuclear Information System (INIS)
Phillips, M.W.; Todd, A.M.M.
1986-01-01
The numerics of a numerical code called GARFIELD (Grumman Aerospace RF fIELD code) designed to calculate the three-dimensional structure of ICRF fields in axisymmetric mirrors is presented. The code solves the electromagnetic wave equation for the electric field using a cold plasma dispersion relation with a small collision term to simulate absorption. The full wave solution including E.B is computed. The fields are Fourier analyzed in the poloidal direction and solved on a grid in the axial and radial directions. A two-dimensional equilibrium can be used as the source of equilibrium data. This allows us to extend previous studies of ICRF wave propagation and absorption in mirrors to include the effect of axial variation of the magnetic field and density. (orig.)
Axisymmetric magnetohydrodynamic equilibria in local polar coordinates
International Nuclear Information System (INIS)
Clemente, R.A.
1982-01-01
The Grad--Shafranov equation for an ideal magnetohydrodynamic axisymmetric toroidal configuration is solved analytically in a local polar coordinate system using a novel method which produces solutions valid up to the second order in the inverse aspect ratio expansion
Adaptative mixed methods to axisymmetric shells
International Nuclear Information System (INIS)
Malta, S.M.C.; Loula, A.F.D.; Garcia, E.L.M.
1989-09-01
The mixed Petrov-Galerkin method is applied to axisymmetric shells with uniform and non uniform meshes. Numerical experiments with a cylindrical shell showed a significant improvement in convergence and accuracy with adaptive meshes. (A.C.A.S.) [pt
Itoh, Tamitake; Yamamoto, Yuko S.
2017-11-01
Electronic transition rates of a molecule located at a crevasse or a gap of a plasmonic nanoparticle (NP) dimer are largely enhanced up to the factor of around 106 due to electromagnetic (EM) coupling between plasmonic and molecular electronic resonances. The coupling rate is determined by mode density of the EM fields at the crevasse and the oscillator strength of the local electronic resonance of a molecule. The enhancement by EM coupling at a gap of plasmonic NP dimer enables us single molecule (SM) Raman spectroscopy. Recently, this type of research has entered a new regime wherein EM enhancement effects cannot be treated by conventional theorems, namely EM mechanism. Thus, such theorems used for the EM enhancement effect should be re-examined. We here firstly summarize EM mechanism by using surface-enhanced Raman scattering (SERS), which is common in EM enhancement phenomena. Secondly, we focus on recent two our studies on probing SM fluctuation by SERS within the spatial resolution of sub-nanometer scales. Finally, we discuss the necessity of re-examining the EM mechanism with respect to two-fold breakdowns of the weak coupling assumption: the breakdown of Kasha's rule induced by the ultra-fast plasmonic de-excitation and the breakdown of the weak coupling by EM coupling rates exceeding both the plasmonic and molecular excitonic dephasing rates.
Czech Academy of Sciences Publication Activity Database
Prikner, Karel; Feygin, F. Z.; Raita, T.
2014-01-01
Roč. 58, č. 2 (2014), s. 326-337 ISSN 0039-3169 Grant - others:European Commission(XE) HPRI 200100132 Institutional research plan: CEZ:AV0Z30120515 Keywords : ionospheric Alfvén resonator * full-wave numerical simulation * EISCAT measurements * standing wave oscillations Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014
Czech Academy of Sciences Publication Activity Database
Prikner, Karel; Feygin, F. Z.; Raita, T.
2014-01-01
Roč. 58, č. 2 (2014), s. 338-341 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : ionospheric Alfvén resonator * EMIC waves * EISCAT measurements Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014
International Nuclear Information System (INIS)
Kim, Se Yun
2009-01-01
This book deals with engineering electromagnetics. It contains seven chapters, which treats understanding of engineering electromagnetics such as magnet and electron spin, current and a magnetic field and an electromagnetic wave, Essential tool for engineering electromagnetics on rector and scalar, rectangular coordinate system and curl vector, electrostatic field with coulomb rule and method of electric images, Biot-Savart law, Ampere law and magnetic force, Maxwell equation and an electromagnetic wave and reflection and penetration of electromagnetic plane wave.
Koshelev, Alexei
2013-03-01
Stacks of intrinsic Josephson-junctions are realized in mesas fabricated out of layered superconducting single crystals, such as Bi2Sr2CaCu2O8 (BSCCO). Synchronization of phase oscillations in different junctions can be facilitated by the coupling to the internal cavity mode leading to powerful and coherent electromagnetic radiation in the terahertz frequency range. An important characteristic of this radiation is the shape of the emission line. A finite line width appears due to different noise sources leading to phase diffusion. We investigated the intrinsic line shape caused by the thermal noise for a mesa fabricated on the top of a BSCCO single crystal. In the ideal case of fully synchronized stack the finite line width is coming from two main contributions, the quasiparticle-current noise inside the mesa and the fluctuating radiation in the base crystal. We compute both contributions and conclude that for realistic mesa's parameters the second mechanism typically dominates. The role of the cavity quality factor in the emission line spectrum is clarified. Analytical results were verified by numerical simulations. In real mesa structures part of the stack may not be synchronized and chaotic dynamics of unsynchronized junctions may determine the real line width. Work supported by UChicago Argonne, LLC, under contract No. DE-AC02-06CH11357.
DEFF Research Database (Denmark)
an impetus or drive to that account: change, innovation, rupture, or discontinuity. Resonances: Historical Essays on Continuity and Change explores the historiographical question of the modes of interrelation between these motifs in historical narratives. The essays in the collection attempt to realize...
Identification of multiple modes of axisymmetric or circularly repetitive structures
International Nuclear Information System (INIS)
Kopff, P.
1983-01-01
The axisymmetric structures, or those composed with circularly repetitive elements, often display multiple modes, which are not easy to separate by modal identification of experimental responses. To be able to solve in situ some problems related to the vibrational behaviour of reactor vessels or other such huge structures, ELECTRICITY DE FRANCE developed a few years ago, experimental capabilities providing heavy harmonic driving forces, and elaborate data acquisition, signal processing and modal identification software, self-contained in an integrated mobile test facility. The modal analysis techniques we have developed with the LABORATOIRE DE MECANIQUE Appliquee of University of BESANCON (FRANCE) were especially suited for identification of multiple or separation of quasi-multiple modes, i.e. very close and strongly coupled resonances. Besides, the curve fitting methods involved, compute the same complex eigen-frequencies for all the vibration pick-ups, for better accuracy of the related eigen-vector components. Moreover, the latest extensions of these algorithms give us the means to deal with non-linear behaviour. The performances of these programs are drawn from some experimental results on axisymmetric or circularly repetitive structure, we tested in our laboratory to validate the computational hypothesis used in models for seismic responses of breeder reactor vessels. (orig.)
Supersonic quasi-axisymmetric vortex breakdown
Kandil, Osama A.; Kandil, Hamdy A.; Liu, C. H.
1991-01-01
An extensive computational study of supersonic quasi-axisymmetric vortex breakdown in a configured circular duct is presented. The unsteady, compressible, full Navier-Stokes (NS) equations are used. The NS equations are solved for the quasi-axisymmetric flows using an implicit, upwind, flux difference splitting, finite volume scheme. The quasi-axisymmetric solutions are time accurate and are obtained by forcing the components of the flowfield vector to be equal on two axial planes, which are in close proximity of each other. The effect of Reynolds number, for laminar flows, on the evolution and persistence of vortex breakdown, is studied. Finally, the effect of swirl ration at the duct inlet is investigated.
Valois, Remi; Vouillamoz, Jean-Michel; Lun, Sambo; Arnout, Ludovic
2018-01-01
Lack of access to water is the primary constraint to development in rural areas of northwestern Cambodia. Communities lack water for both domestic and irrigation purposes. To provide access to drinking water, governmental and aid agencies have focused on drilling shallow boreholes but they have not had a clear understanding of groundwater potential. The goal of this study has been to improve hydrogeological knowledge of two districts in Oddar Meanchey Province by analyzing borehole lithologs and geophysical data sets. The comparison of 55 time-domain electromagnetic (TEM) soundings and lithologs, as well as 66 magnetic-resonance soundings (MRS) with TEM soundings, allows a better understanding of the links between geology, electrical resistivity and hydrogeological parameters such as the specific yield (S y) derived from MRS. The main findings are that water inflow and S y are more related to electrical resistivity and elevation than to the litholog description. Indeed, conductive media are associated with a null value of S y, whereas resistive rocks at low elevation are always linked to strictly positive S y. A new methodology was developed to create maps of groundwater reserves based on 612 TEM soundings and the observed relationship between resistivity and S y. TEM soundings were inverted using a quasi-3D modeling approach called `spatially constrained inversion'. Such maps will, no doubt, be very useful for borehole siting and in the economic development of the province because they clearly distinguish areas of high groundwater-reserves potential from areas that lack reserves.
Irons, Trevor P.; Martin, Kathryn; Finn, Carol A.; Bloss, Benjamin; Horton, Robert J.
2014-01-01
Surface and laboratory Nuclear Magnetic Resonance (NMR) measurements combined with transient electromagnetic (TEM) data are powerful tools for subsurface water detection. Surface NMR (sNMR) and TEM soundings, laboratory NMR, complex resistivity, and X-Ray Diffraction (XRD) analysis were all conducted to characterise the distribution of water within Sherman Crater on Mt. Baker, WA. Clay rich rocks, particularly if water saturated, can weaken volcanoes, thereby increasing the potential for catastrophic sector collapses that can lead to far-travelled, destructive debris flows. Detecting the presence and volume of shallow groundwater is critical for evaluating these landslide hazards. The TEM data identified a low resistivity layer (conditions which would allow for sNMR detection of the clay layer are investigated. Using current instrumentation the combined analysis of the TEM and sNMR data allow for valuable characterisation of the groundwater system in the crater. The sNMR is able to reduce the uncertainty of the TEM in regards to the presence of a bulk water layer, a valuable piece of information in hazard assessment.
Qin, J. J.; Jones, M.; Shiota, T.; Greenberg, N. L.; Firstenberg, M. S.; Tsujino, H.; Zetts, A. D.; Sun, J. P.; Cardon, L. A.; Odabashian, J. A.;
2000-01-01
AIM: The aim of this study was to investigate the feasibility and accuracy of using symmetrically rotated apical long axis planes for the determination of left ventricular (LV) volumes with real-time three-dimensional echocardiography (3DE). METHODS AND RESULTS: Real-time 3DE was performed in six sheep during 24 haemodynamic conditions with electromagnetic flow measurements (EM), and in 29 patients with magnetic resonance imaging measurements (MRI). LV volumes were calculated by Simpson's rule with five 3DE methods (i.e. apical biplane, four-plane, six-plane, nine-plane (in which the angle between each long axis plane was 90 degrees, 45 degrees, 30 degrees or 20 degrees, respectively) and standard short axis views (SAX)). Real-time 3DE correlated well with EM for LV stroke volumes in animals (r=0.68-0.95) and with MRI for absolute volumes in patients (r-values=0.93-0.98). However, agreement between MRI and apical nine-plane, six-plane, and SAX methods in patients was better than those with apical four-plane and bi-plane methods (mean difference = -15, -18, -13, vs. -31 and -48 ml for end-diastolic volume, respectively, Pmethods of real-time 3DE correlated well with reference standards for calculating LV volumes. Balancing accuracy and required time for these LV volume measurements, the apical six-plane method is recommended for clinical use.
DEFF Research Database (Denmark)
This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis......, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc....
Boundary element method for internal axisymmetric flow
Directory of Open Access Journals (Sweden)
Gokhman Alexander
1999-01-01
Full Text Available We present an accurate fast method for the computation of potential internal axisymmetric flow based on the boundary element technique. We prove that the computed velocity field asymptotically satisfies reasonable boundary conditions at infinity for various types of inlet/exit. Computation of internal axisymmetric potential flow is an essential ingredient in the three-dimensional problem of computation of velocity fields in turbomachines. We include the results of a practical application of the method to the computation of flow in turbomachines of Kaplan and Francis types.
Shtemler, Yu.; Mond, M.; Liverts, E.
2018-02-01
The excitation of nonaxisymmetric quasi-resonant triads by clustering around a dominant axisymmetric explosively unstable magnetorotational instability (MRI) in Keplerian discs is investigated. Clustering, namely, the mutual interactions of a large number of quasi-resonant triads that are connected by a single dominant explosively unstable axisymmetric triad, is invoked in order to provide a viable mechanism for the stabilization of the explosive nature of the latter. The results, however, are of wider scope as the proposed clustering scenario also provides a strong mechanism for the excitation of high-amplitude nonaxisymmetric perturbations. The latter play a major role in the nonlinear evolution of the MRI on the route to fully developed turbulence.
Electron cyclotron current drive efficiency in an axisymmetric tokamak
Energy Technology Data Exchange (ETDEWEB)
Gutierrez-Tapia, C.; Beltran-Plata, M. [Instituto Nacional de Investigaciones Nucleares, Dept. de Fisica, Mexico D.F. (Mexico)
2004-07-01
The neoclassical transport theory is applied to calculate electron cyclotron current drive (ECCD) efficiency in an axisymmetric tokamak in the low-collisionality regime. The tokamak ordering is used to obtain a system of equations that describe the dynamics of the plasma where the nonlinear ponderomotive (PM) force due to high-power radio-frequency (RF) waves is included. The PM force is produced around an electron cyclotron resonant surface at a specific poloidal location. The ECCD efficiency is analyzed in the cases of first and second harmonics (for different impinging angles of the RF waves) and it is validated using experimental parameter values from TCV and T-10 tokamaks. The results are in agreement with those obtained by means of Green's function techniques. (authors)
Fadel, M Ali; El-Gebaly, Reem H; Mohamed, Shaimaa A; Abdelbacki, Ashraf M M
2017-12-09
Isolated Agrobacterium tumefaciens was exposed to different extremely low frequencies of square amplitude modulated waves (QAMW) from two generators to determine the resonance frequency that causes growth inhibition. The carrier was 10 MHz sine wave with amplitude ±10 Vpp which was modulated by a second wave generator with a modulation depth of ± 2Vpp and constant field strength of 200 V/m at 28 °C. The exposure of A. tumefaciens to 1.0 Hz QAMW for 90 min inhibited the bacterial growth by 49.2%. In addition, the tested antibiotics became more effective against A. tumefaciens after the exposure. Furthermore, results of DNA, dielectric relaxation and TEM showed highly significant molecular and morphological changes due to the exposure to 1.0 Hz QAMW for 90 min. An in-vivo study has been carried out on healthy tomato plants to test the pathogenicity of A. tumefaciens before and after the exposure to QAMW at the inhibiting frequency. Symptoms of crown gall and all pathological symptoms were more aggressive in tomato plants treated with non-exposed bacteria, comparing with those treated with exposed bacteria. We concluded that, the exposure of A. tumefaciens to 1.0 Hz QAMW for 90 min modified its cellular activity and DNA structure, which inhibited the growth and affected the microbe pathogenicity. Copyright © 2017 Elsevier Inc. All rights reserved.
Feedback stabilization of axisymmetric modes in tokamaks
International Nuclear Information System (INIS)
Jardin, S.C.; Larrabee, D.A.
1982-01-01
Noncircular tokamak plasmas can be unstable to ideal MHD axisymmetric instabilities. Passive conductors with finite resistivity will at best slow down these instabilities to the resistive (L/R) time of the conductors. An active feedback system far from the plasma which responds on this resistive time can stabilize the system provided its mutual inductance with the passive coils is small enough
Magneto-hydrodynamically stable axisymmetric mirrorsa)
Ryutov, D. D.; Berk, H. L.; Cohen, B. I.; Molvik, A. W.; Simonen, T. C.
2011-09-01
Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.
Magneto-hydrodynamically stable axisymmetric mirrors
Energy Technology Data Exchange (ETDEWEB)
Ryutov, D. D.; Cohen, B. I.; Molvik, A. W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Berk, H. L. [University of Texas, Austin, Texas 78712 (United States); Simonen, T. C. [University of California, Berkeley, California 94720 (United States)
2011-09-15
Making axisymmetric mirrors magnetohydrodynamically (MHD) stable opens up exciting opportunities for using mirror devices as neutron sources, fusion-fission hybrids, and pure-fusion reactors. This is also of interest from a general physics standpoint (as it seemingly contradicts well-established criteria of curvature-driven instabilities). The axial symmetry allows for much simpler and more reliable designs of mirror-based fusion facilities than the well-known quadrupole mirror configurations. In this tutorial, after a summary of classical results, several techniques for achieving MHD stabilization of the axisymmetric mirrors are considered, in particular: (1) employing the favorable field-line curvature in the end tanks; (2) using the line-tying effect; (3) controlling the radial potential distribution; (4) imposing a divertor configuration on the solenoidal magnetic field; and (5) affecting the plasma dynamics by the ponderomotive force. Some illuminative theoretical approaches for understanding axisymmetric mirror stability are described. The applicability of the various stabilization techniques to axisymmetric mirrors as neutron sources, hybrids, and pure-fusion reactors are discussed; and the constraints on the plasma parameters are formulated.
The spectrum of axisymmetric torsional Alfven waves
International Nuclear Information System (INIS)
Sy, W.N.
1977-03-01
The spectrum of axisymmetric torsional Alfven waves propagating in a cylindrical, non-uniform, resistive plasma waveguide has been analysed by a method of singular perturbations. A simple condition has been derived which predicts whether the spectrum is continuous or discrete under given physical conditions. Application of this result to resolve an apparent discrepancy in experimental observations is briefly discussed. (Author)
Axisymmetric solution with charge in general relativity
International Nuclear Information System (INIS)
Arutyunyan, G.G.; Papoyan, V.V.
1989-01-01
The possibility of generating solutions to the equations of general relativity from known solutions of the generalized theory of gravitation and vice versa is proved. An electrovac solution to Einstein's equations that describes a static axisymmetric gravitational field is found. 14 refs
Regenerative feedback resonant circuit
Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.
2014-09-02
A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.
Axisymmetric instability in a noncircular tokamak
International Nuclear Information System (INIS)
Lipschultz, B.
1979-10-01
The stability of dee, inverse-dee and square cross section plasmas to axisymmetric modes has been investigated experimentally in Tokapole II, a tokamak with a four-null poloidal divertor. Experimental results are closely compared with predictions of two numerical stability codes - the PEST code (ideal MHD, linear stability) adapted to tokapole geometry and a code which follows the nonlinear evolution of shapes similar to tokapole equilibria
Numerical description of cavitation on axisymmetric bodies
Energy Technology Data Exchange (ETDEWEB)
Hickox, C.E.; Hailey, C.E.; Wolfe, W.P.; Watts, H.A.; Gross, R.J.; Ingber, M.S.
1988-01-01
This paper reports on ongoing studies which are directed toward the development of predictive techniques for the modeling of steady cavitation on axisymmetric bodies. The primary goal of the modeling effort is the prediction of cavity shape and pressure distribution from which forces and moments can be calculated. Here we present an overview of the modeling techniques developed and compare predictions with experimental data obtained from water tunnel tests for both limited and supercavitation. 14 refs., 4 figs.
Axisymmetric vibrations of thin shells of revolution
International Nuclear Information System (INIS)
Suzuki, Katsuyoshi; Kikuchi, Norio; Kosawada, Tadashi; Takahashi, Shin
1983-01-01
The problem of free vibration of axisymmetric shells of revolution is important in connection with the design of pressure vessels, chemical equipment, aircrafts, structures and so on. In this study, the axisymmetrical vibration of a thin shell of revolution having a constant curvature in meridian direction was analyzed by thin shell theory. First, the Lagrangian during one period of the vibration of a shell of revolution was determined by the primary approximate theory of Love, and the vibration equations and boundary conditions were derived from its stopping condition. The vibration equations were strictly analyzed by using the series solution. The basic equations for the strain and strain energy of a shell were based on those of Novozhilov. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. The theory and the numerical calculation ore described. Especially in the frequency curves, the waving phenomena were observed frequently, which were not seen in non-axisymmetric vibration, accordingly also the vibration mode changed in complex state on the frequency curves of same order. The numerical calculation was carried out in the large computer center in Tohoku University. (Kako, I.)
Axisymmetric ideal magnetohydrodynamic equilibria with incompressible flows
International Nuclear Information System (INIS)
Tasso, H.; Throumoulopoulos, G.N.
1997-12-01
It is shown that the ideal MHD equilibrium states of an axisymmetric plasma with incompressible flows are governed by an elliptic partial differential equation for the poloidal magnetic flux function ψ containing five surface quantities along with a relation for the pressure. Exact equilibria are constructed including those with non vanishing poloidal and toroidal flows and differentially varying radial electric fields. Unlike the case in cylindrical incompressible equilibria with isothermal magnetic surfaces which should have necessarily circular cross sections [G. N. Throumoulopoulos and H. Tasso, Phys. Plasmas 4, 1492 (1997)], no restriction appears on the shapes of the magnetic surfaces in the corresponding axisymmetric equilibria. The latter equilibria satisfy a set of six ordinary differential equations which for flows parallel to the magnetic field B can be solved semianalytically. In addition, it is proved the non existence of incompressible axisymmetric equilibria with (a) purely poloidal flows and (b) non-parallel flows with isothermal magnetic surfaces and vertical stroke B vertical stroke = vertical stroke B vertical stroke (ψ) (omnigenous equilibria). (orig.)
Surface pressure drag for hydrostatic two-layer flow over axisymmetric mountains
Energy Technology Data Exchange (ETDEWEB)
Leutbecher, M.
2000-07-01
The effect of partial reflections on surface pressure drag is investigated for hydrostatic gravity waves in two-layer flow with piecewise constant buoyancy frequency. The variation of normalized surface pressure drag with interface height is analyzed for axisymmetric mountains. The results are compared with the familiar solution for infinitely long ridges. The drag for the two-layer flow is normalized with the drag of one-layer flow, which has the buoyancy frequency of the lower layer. An analytical expression for the normalized drag of axisymmetric mountains is derived from linear theory of steady flow. Additionally, two-layer flow over finite-height axisymmetric mountains is simulated numerically for flow with higher stability in the upper layer. The temporal evolution of the surface pressure drag is examined in a series of experiments with different interface and mountain heights. The focus is on the linear regime and the nonlinear regime of nonbreaking gravity waves. The dispersion of gravity waves in flow over isolated mountains prevents that the entire wave spectrum is in resonance at the same interface height, which is the case in hydrostatic flow over infinitely long ridges. In consequence, the oscillation of the normalized drag with interface height is smaller for axisymmetric mountains than for infinitely long ridges. However, even for a reflection coefficient as low as 1/3 the drag of an axisymmetric mountain can be amplified by 50% and reduced by 40%. The nonlinear drag becomes steady in the numerical experiments in which no wave breaking occurs. The steady state nonlinear drag agrees quite well with the prediction of linear theory if the linear drag is computed for a slightly lowered interface. (orig.)
Numerical simulation of the generation mechanism of axisymmetric supersonic jet screech tones
Li, X. D.; Gao, J. H.
2005-08-01
In this paper an axisymmetric computational aeroacoustic procedure is developed to investigate the generation mechanism of axisymmetric supersonic jet screech tones. The axisymmetric Navier-Stokes equations and the two equations standard k-ɛ turbulence model modified by Turpin and Troyes ["Validation of a two-equation turbulence model for axisymmetric reacting and non-reaction flows," AIAA Paper No. 2000-3463 (2000)] are solved in the generalized curvilinear coordinate system. A generalized wall function is applied in the nozzle exit wall region. The dispersion-relation-preserving scheme is applied for space discretization. The 2N storage low-dissipation and low-dispersion Runge-Kutta scheme is employed for time integration. Much attention is paid to far-field boundary conditions and turbulence model. The underexpanded axisymmetric supersonic jet screech tones are simulated over the Mach number from 1.05 to 1.2. Numerical results are presented and compared with the experimental data by other researchers. The simulated wavelengths of A0, A1, A2, and B modes and part of simulated amplitudes agree very well with the measurement data by Ponton and Seiner ["The effects of nozzle exit lip thickness on plume resonance," J. Sound Vib. 154, 531 (1992)]. In particular, the phenomena of modes jumping have been captured correctly although the numerical procedure has to be improved to predict the amplitudes of supersonic jet screech tones more accurately. Furthermore, the phenomena of shock motions are analyzed. The predicted splitting and combination of shock cells are similar with the experimental observations of Panda ["Shock oscillation in underexpanded screeching jets," J. Fluid. Mech. 363, 173 (1998)]. Finally, the receptivity process is numerically studied and analyzed. It is shown that the receptivity zone is associated with the initial thin shear layer, and the incoming and reflected sound waves.
Gravitoelectromagnetic resonances
International Nuclear Information System (INIS)
Tsagas, Christos G.
2011-01-01
The interaction between gravitational and electromagnetic radiation has a rather long research history. It is well known, in particular, that gravity-wave distortions can drive propagating electromagnetic signals. Since forced oscillations provide the natural stage for resonances to occur, gravitoelectromagnetic resonances have been investigated as a means of more efficient gravity-wave detection methods. In this report, we consider the coupling between the Weyl and the Maxwell fields on a Minkowski background, which also applies to astrophysical environments where gravity is weak, at the second perturbative level. We use covariant methods that describe gravitational waves via the transverse component of the shear, instead of pure-tensor metric perturbations. The aim is to calculate the properties of the electromagnetic signal, which emerges from the interaction of its linear counterpart with an incoming gravitational wave. Our analysis shows how the wavelength and the amplitude of the gravitationally driven electromagnetic wave vary with the initial conditions. More specifically, for certain initial data, the amplitude of the induced electromagnetic signal is found to diverge. Analogous, diverging, gravitoelectromagnetic resonances were also reported in cosmology. Given that, we extend our Minkowski space study to cosmology and discuss analogies and differences in the physics and in the phenomenology of the Weyl-Maxwell coupling between the aforementioned two physical environments.
Electromagnetic field properties in the vicinity of a massive wormhole
Energy Technology Data Exchange (ETDEWEB)
Novikov, I. D.; Shatskiy, A. A., E-mail: shatskiy@asc.rssi.ru [Russian Academy of Sciences, Astro Space Centre, Lebedev Physical Institute (Russian Federation)
2011-12-15
It is proved that not only massless but also traversable massive wormholes can have electromagnetic 'hair.' An analysis is also presented of the passage from a traversable wormhole to the limit of a Reissner-Nordstroem black hole, with the corresponding disappearance of 'hair.' A general method is developed for solving stationary axisymmetric Maxwell's equations in the field of a massive, spherically symmetric wormhole. As a particular example of application of the method, a solution is found to the axisymmetric magnetostatic problem for a current loop in the field of the Bronnikov-Ellis-Morris-Thorne wormhole.
Low Cost Method of Manufacturing Cooled Axisymmetric Scramjets, Phase I
National Aeronautics and Space Administration — Scramjet engine developers are working on advanced axisymmetric engine concepts that may not be feasible due to limitations of currently available manufacturing...
International Nuclear Information System (INIS)
Sarma, J.; Robson, P.N.
1979-01-01
The two dimensional transmission line matrix (TLM) numerical method has been adapted to compute electromagnetic field distributions in cylindrical co-ordinates and it is applied to evaluate the radiation loss from a charge bunch passing through a 'pill-box' resonator. The computer program has been developed to calculate not only the total energy loss to the resonator but also that component of it which exists in the TM 010 mode. The numerically computed results are shown to agree very well with the analytically derived values as found in the literature which, therefore, established the degree of accuracy that is obtained with the TLM method. The particular features of computational simplicity, numerical stability and the inherently time-domain solutions produced by the TLM method are cited as additional, attractive reasons for using this numerical procedure in solving such problems. (Auth.)
Microfluidic step-emulsification in axisymmetric geometry.
Chakraborty, I; Ricouvier, J; Yazhgur, P; Tabeling, P; Leshansky, A M
2017-10-25
Biphasic step-emulsification (Z. Li et al., Lab Chip, 2015, 15, 1023) is a promising microfluidic technique for high-throughput production of μm and sub-μm highly monodisperse droplets. The step-emulsifier consists of a shallow (Hele-Shaw) microchannel operating with two co-flowing immiscible liquids and an abrupt expansion (i.e., step) to a deep and wide reservoir. Under certain conditions the confined stream of the disperse phase, engulfed by the co-flowing continuous phase, breaks into small highly monodisperse droplets at the step. Theoretical investigation of the corresponding hydrodynamics is complicated due to the complex geometry of the planar device, calling for numerical approaches. However, direct numerical simulations of the three dimensional surface-tension-dominated biphasic flows in confined geometries are computationally expensive. In the present paper we study a model problem of axisymmetric step-emulsification. This setup consists of a stable core-annular biphasic flow in a cylindrical capillary tube connected co-axially to a reservoir tube of a larger diameter through a sudden expansion mimicking the edge of the planar step-emulsifier. We demonstrate that the axisymmetric setup exhibits similar regimes of droplet generation to the planar device. A detailed parametric study of the underlying hydrodynamics is feasible via inexpensive (two dimensional) simulations owing to the axial symmetry. The phase diagram quantifying the different regimes of droplet generation in terms of governing dimensionless parameters is presented. We show that in qualitative agreement with experiments in planar devices, the size of the droplets generated in the step-emulsification regime is independent of the capillary number and almost insensitive to the viscosity ratio. These findings confirm that the step-emulsification regime is solely controlled by surface tension. The numerical predictions are in excellent agreement with in-house experiments with the axisymmetric
Reversed straining in axisymmetric compression test
DEFF Research Database (Denmark)
Arentoft, Mogens; Wanheim, Tarras; Lindegren, Maria
2005-01-01
A large group of the cold forging processes is carried out in a thick – walled container with the deformation force transmitted through a punch moving axially in the container. The work piece, being entrapped between punch and container will expand and exert a radial pressure resulting in an expa...... to simulate these conditions a reversed axisymmetrical material tester is designed and constructed. Three different materials were tested, aluminum alloy AA6082, technically pure copper (99.5%) and cold forging steel Ma8, at different temperatures found during cold forging....
An axisymmetric inertia-gravity wave generator
Maurer, P.; Ghaemsaidi, S. J.; Joubaud, S.; Peacock, T.; Odier, P.
2017-10-01
There has been a rich interplay between laboratory experimental studies of internal waves and advancing understanding of their role in the ocean and atmosphere. In this study, we present and demonstrate the concept for a new form of laboratory internal wave generator that can excite axisymmetric wave fields of arbitrary radial structure. The construction and operation of the generator are detailed, and its capabilities are demonstrated through a pair of experiments using a Bessel function and a bourrelet (i.e., ring-shaped) configuration. The results of the experiments are compared with the predictions of an accompanying analytical model.
Numerical determination of axisymmetric toroidal magnetohydrodynamic equilibria
International Nuclear Information System (INIS)
Johnson, J.L.; Dalhed, H.E.; Greene, J.M.
1978-07-01
Numerical schemes for the determination of stationary axisymmetric toroidal equilibria appropriate for modeling real experimental devices are given. Iterative schemes are used to solve the elliptic nonlinear partial differential equation for the poloidal flux function psi. The principal emphasis is on solving the free boundary (plasma-vacuum interface) equilibrium problem where external current-carrying toroidal coils support the plasma column, but fixed boundary (e.g., conducting shell) cases are also included. The toroidal current distribution is given by specifying the pressure and either the poloidal current or the safety factor profiles as functions of psi. Examples of the application of the codes to tokamak design at PPPL are given
Ideal magnetohydrodynamic stability of axisymmetric mirrors
International Nuclear Information System (INIS)
D'Ippolito, D.A.; Hafizi, B.; Myra, J.R.
1982-01-01
The governing partial differential equation for general mode-number pressure-driven ballooning modes in a long-thin, axisymmetric plasma is derived within the context of ideal magnetohydrodynamics. It is shown that the equation reduces in special limits to the Hain--Luest equation, the high-m diffuse p(psi) ballooning equation, and the low-m sharp-boundary equation. A low-β analytic solution of the full partial differential equation is presented for quasiflute modes in an idealized tandem mirror model to elucidate the relationship of the various limiting cases
Topological fluid mechanics of Axisymmetric Flow
DEFF Research Database (Denmark)
Brøns, Morten
1998-01-01
Topological fluid mechanics in the sense of the present paper is the study and classification of flow patterns close to a critical point. Here we discuss the topology of steady viscous incompressible axisymmetric flows in the vicinity of the axis. Following previous studies the velocity field v...... to the authors knowledge has not been used systematically to high orders in topological fluid mechanics. We compare the general results with experimental and computational results on the Vogel-Ronneberg flow. We show that the topology changes observed when recirculating bubbles on the vortex axis are created...
Static axisymmetric discs and gravitational collapse
Energy Technology Data Exchange (ETDEWEB)
Chamorro, A.; Gregory, R.; Stewart, J.M.
1987-09-08
Regular static axisymmetric vacuum solutions of Einstein's field equations representing the exterior field of a finite thin disc are found. These are used to describe the slow collapse of a disc-like object. If no conditions are placed on the matter, a naked singularity is formed and the cosmic censorship hypothesis would be violated. Imposition of the weak energy condition, however, prevents slow collapse to a singularity and preserves the validity of this hypothesis. The validity of the hoop conjecture is also discussed.
Electromagnetic radiation optimum neutralizer
International Nuclear Information System (INIS)
Smirnov, Igor
2002-01-01
This particular article relates to subtle electrical effects, and provides some evidence of a fundamental nature on how subtle low frequency electromagnetic fields might be utilized to protect human body against harmful effects of high frequencies electromagnetic radiation. I have focused my efforts on definite polar polymer compound named EMRON which is patented in the USA. This polar polymer compound can be excited by external high frequencies electromagnetic fields to generate subtle low frequency oscillations that are beneficial for cellular life structures. This concept is based on the possibility of existence of resonance phenomenon between polar polymers and biopolymers such as proteins, nucleic acids, lipids, etc. Low frequency patterns generated by defined polar polymer compound can interact with biostructures and transmit the signals that support and improve cellular functions in the body. The mechanism of this process was confirmed by number of studies. The animal (including human) brain is affected by electromagnetic waves to the extent that production of Alpha or Theta waves can be directly induced into brain by carrying an ELF (extremely low frequency, 5-12 Hz) signal on a microwave carrier frequency. EMRON does not reduce the power of electromagnetic fields. It 'shields' the cellular structures of the body against the harmful effects of EMR. The radiation is still entering the body but the neutralizing effect of EMRON renders the radiation harmless
Energy Technology Data Exchange (ETDEWEB)
Yamashita, H; Marinova, I; Cingoski, V [eds.
2002-07-01
These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics.
International Nuclear Information System (INIS)
Yamashita, H.; Marinova, I.; Cingoski, V.
2002-01-01
These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics
Electromagnetic modeling in accelerator designs
International Nuclear Information System (INIS)
Cooper, R.K.; Chan, K.C.D.
1990-01-01
Through the years, electromagnetic modeling using computers has proved to be a cost-effective tool for accelerator designs. Traditionally, electromagnetic modeling of accelerators has been limited to resonator and magnet designs in two dimensions. In recent years with the availability of powerful computers, electromagnetic modeling of accelerators has advanced significantly. Through the above conferences, it is apparent that breakthroughs have been made during the last decade in two important areas: three-dimensional modeling and time-domain simulation. Success in both these areas have been made possible by the increasing size and speed of computers. In this paper, the advances in these two areas will be described
International Nuclear Information System (INIS)
Bosanac, Slobodan Danko
2016-01-01
This book is devoted to theoretical methods used in the extreme circumstances of very strong electromagnetic fields. The development of high power lasers, ultrafast processes, manipulation of electromagnetic fields and the use of very fast charged particles interacting with other charges requires an adequate theoretical description. Because of the very strong electromagnetic field, traditional theoretical approaches, which have primarily a perturbative character, have to be replaced by descriptions going beyond them. In the book an extension of the semi-classical radiation theory and classical dynamics for particles is performed to analyze single charged atoms and dipoles submitted to electromagnetic pulses. Special attention is given to the important problem of field reaction and controlling dynamics of charges by an electromagnetic field.
Fast axisymmetric stability calculations using variational techniques
International Nuclear Information System (INIS)
Haney, S.W., Pearlstein, L.D.; Bulmer, R.H.
1991-01-01
A procedure for treating the axisymmetric (n = 0) stability of diverted plasmas in the presence of arbitrary, but toroidally symmetric, structures and active feedback circuits has been developed and implemented as a module in the TEQ free-boundary equilibrium code. This procedure is based on a variational solution of the ideal MHD normal mode equations. Inertia is ordered small but provides a constraint to allow the calculation of the poloidal and toroidal components of the plasma displacement. Feedback based on flux loop measurements is handled by introducing an adjoint system into the variational principle. Approximately 200 trial functions for the radial component of the plasma displacement and 200 magnetic surfaces are employed to obtain highly accurate estimates of the passive growth rate and the non-rigid eigenfunction. Nevertheless, the method is extremely fast: typically 10-20 sec of Cray 2 CPU time are required to analyze a realistic tokamak configuration. This speed, along with the direct coupling to the MHD equilibrium solver, allows interactive investigations of tokamak axisymmetric stability. Benchmarks with TSC and GATO are presented along with parameter scans for ITER and BPX. The results emphasize the importance of considering non-rigid mode effects which for ITER, yield higher nominal growth rates (non-rigid: 45 Hz, rigid: 25 Hz) and atypical internal inductance dependence (smaller l i more unstable)
Axisymmetric vibrations of thick shells of revolution
International Nuclear Information System (INIS)
Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin
1983-01-01
Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)
Multitude scaling laws in axisymmetric turbulent wake
Layek, G. C.; Sunita
2018-03-01
We establish theoretically multitude scaling laws of a self-similar (statistical) axisymmetric turbulent wake. At infinite Reynolds number limit, the flow evolves as general power law and a new exponential law of streamwise distance, consistent with the criterion of equilibrium similarity hypothesis. We found power law scalings for components of the homogeneous dissipation rate (ɛ) obeying the non-Richardson-Kolmogorov cascade as ɛu˜ku3 /2/(l R elm ) , ɛv˜kv3 /2/l , kv˜ku/R el2 m, 0 stress, l is the local length scale, and Rel is the Reynolds number. The Richardson-Kolmogorov cascade corresponds to m = 0. For m ≈ 1, the power law agrees with non-equilibrium scaling laws observed in recent experiments of the axisymmetric wake. On the contrary, the exponential scaling law follows the above dissipation law with different regions of existence for power index m = 3. At finite Reynolds number with kinematic viscosity ν, scalings obey the dissipation laws ɛu ˜ νku/l2 and ɛv ˜ νkv/l2 with kv˜ku/R eln. The value of n is preferably 0 and 2. Different possibilities of scaling laws and symmetry breaking process are discussed at length.
Axisymmetric modeling of prestressing tendons in nuclear containment dome
Energy Technology Data Exchange (ETDEWEB)
Jeon, Se-Jin [DAEWOO E and C, Institute of Construction Technology, 60 Songjook-dong, Jangan-gu, Suwon, Kyonggi 440-210 (Korea, Republic of)]. E-mail: jsj@dwconst.co.kr; Chung, Chul-Hun [Department of Civil and Environmental Engineering, Dankook University, San 8, Hannam-dong, Youngsan-gu, Seoul 140-714 (Korea, Republic of)
2005-12-15
Simple axisymmetric modeling of a nuclear containment building has been often employed in practice to estimate structural behavior for the axisymmetric loadings such as internal pressure. In this case, the prestressing tendons placed in the containment dome should be axisymmetrically approximated, since most dome tendons are not arranged in an axisymmetric manner. Some procedures are proposed that can realistically implement the actual three-dimensional tendon stiffness and prestressing effect into the axisymmetric model. Prestressing tendons, which are arranged in two or three ways depending on a containment type, are converted into the equivalent layer to consider the stiffness contribution in meridional and hoop directions. In order to reflect the prestressing effect, the equivalent load method and the initial stress method are devised, respectively, and the corresponding loads or stresses are derived in terms of the axisymmetric model. The proposed schemes are verified through some numerical examples comparing the results of the axisymmetric models to those of the actual three-dimensional model. The examples show that the proper level of the prestressing in the hoop direction of the axisymmetric dome plays an important role in tracing the actual behavior induced by the prestressing. Finally, some correction factors are discussed that can further improve the analysis results.
Axisymmetric multiphase lattice Boltzmann method for generic equations of state
Reijers, S.A.; Gelderblom, H.; Toschi, F.
2016-01-01
We present an axisymmetric lattice Boltzmann model based on the Kupershtokh et al. multiphase model that is capable of solving liquid–gas density ratios up to 103. Appropriate source terms are added to the lattice Boltzmann evolution equation to fully recover the axisymmetric multiphase conservation
Relativistic equations for axisymmetric gravitational collapse with escaping neutrinos
International Nuclear Information System (INIS)
Patel, M.D.
1979-01-01
Einstein's field equations for the dynamics of a self-gravitating axially symmetric source of a perfect fluid, presented by Chandrasekhar and Friedman (1964), are modified to allow emission of neutrinos. The boundary conditions at the outer surface of the radiating axisymmetric source are obtained by matching to an exterior solution of an axisymmetric rotating, radiating core. (auth.)
Axisymmetric modeling of prestressing tendons in nuclear containment dome
International Nuclear Information System (INIS)
Jeon, Se-Jin; Chung, Chul-Hun
2005-01-01
Simple axisymmetric modeling of a nuclear containment building has been often employed in practice to estimate structural behavior for the axisymmetric loadings such as internal pressure. In this case, the prestressing tendons placed in the containment dome should be axisymmetrically approximated, since most dome tendons are not arranged in an axisymmetric manner. Some procedures are proposed that can realistically implement the actual three-dimensional tendon stiffness and prestressing effect into the axisymmetric model. Prestressing tendons, which are arranged in two or three ways depending on a containment type, are converted into the equivalent layer to consider the stiffness contribution in meridional and hoop directions. In order to reflect the prestressing effect, the equivalent load method and the initial stress method are devised, respectively, and the corresponding loads or stresses are derived in terms of the axisymmetric model. The proposed schemes are verified through some numerical examples comparing the results of the axisymmetric models to those of the actual three-dimensional model. The examples show that the proper level of the prestressing in the hoop direction of the axisymmetric dome plays an important role in tracing the actual behavior induced by the prestressing. Finally, some correction factors are discussed that can further improve the analysis results
An omnidirectional electromagnetic absorber made of metamaterials
International Nuclear Information System (INIS)
Cheng Qiang; Cui Tiejun; Jiang Weixiang; Cai Bengeng
2010-01-01
In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.
Measurement and control systems for an imaging electromagnetic flow metre.
Zhao, Y Y; Lucas, G; Leeungculsatien, T
2014-03-01
Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the 'weight value' theory to reconstruct velocity profiles is interfaced with a 'Microrobotics VM1' microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller. © 2013 ISA Published by ISA All rights reserved.
Propagation of a hybrid inferior wave in axisymmetrical plasma
International Nuclear Information System (INIS)
Fivaz, M.; Appert, K.; Krlin, L.
1990-05-01
The linear propagation of hybrid inferior waves in an axisymmetrical plasma (magnetohydrodynamic equilibrium of the Soloviev type) has been numerically simulated. The evolution of k // (component of the wave vector k parallel to the magnetic field B), important for current drive modelling, has been studied as a function of the geometric parameters of the equilibrium: aspect ratio, ellipticity and triangularity. The results show that k // depends abruptly on the parameters; the engendered structures are very rich. Two mechanisms by which k // increases have been shown: the 'resonance' occurring in small bands of the space of the parameters and which is associated with trajectories in (R,Z) near stabilization; a stochastic evolution resembling diffusion in equlibriums of very high triangularity. However, a strong increase of k // of a part of the waves, susceptible of engendering a current in the plasma, has only been observed in a minority of cases. In literature current drive experiments have been reported which work and whose parameters are a priori such that our model cannot be expected to show the desired growth of k // . Consequently, our model, which is similar to normally used models, does not explain the current drive. 5 refs., 16 figs
On the choice of electromagnetic model for short high-intensity arcs, applied to welding
International Nuclear Information System (INIS)
Choquet, Isabelle; Shirvan, Alireza Javidi; Nilsson, Håkan
2012-01-01
We have considered four different approaches for modelling the electromagnetic fields of high-intensity electric arcs: (i) three-dimensional, (ii) two-dimensional axi-symmetric, (iii) the electric potential formulation and (iv) the magnetic field formulation. The underlying assumptions and the differences between these models are described in detail. Models (i) to (iii) reduce to the same limit for an axi-symmetric configuration with negligible radial current density, contrary to model (iv). Models (i) to (iii) were retained and implemented in the open source CFD software OpenFOAM. The simulation results were first validated against the analytic solution of an infinite electric rod. Perfect agreement was obtained for all the models tested. The electromagnetic models (i) to (iii) were then coupled with thermal fluid mechanics, and applied to axi-symmetric gas tungsten arc welding test cases with short arc (2, 3 and 5 mm) and truncated conical electrode tip. Models (i) and (ii) lead to the same simulation results, but not model (iii). Model (iii) is suited in the specific limit of long axi-symmetric arc with negligible electrode tip effect, i.e. negligible radial current density. For short axi-symmetric arc with significant electrode tip effect, the more general axi-symmetric formulation of model (ii) should instead be used. (paper)
Jet flow issuing from an axisymmetric pipe-cavity-orifice nozzle
Directory of Open Access Journals (Sweden)
Broučková Zuzana
2016-01-01
Full Text Available An axisymmetric air jet flow is experimentally investigated under passive flow control. The jet issues from a pipe of the inner diameter and length of 10 mm and 150 mm which is equipped with an axisymmetric cavity at the pipe end. The cavity operates as a resonator creating self-sustained acoustic excitations of the jet flow. A mechanism of excitations is rather complex – in comparison with a common Helmholtz resonator. The experiments were performed using flow visualization, microphone measurements and time-mean velocity measurements by the Pitot probe. The power spectral density (PSD and the sound pressure level (SPL were evaluated from microphone measurements. The jet Reynolds number ranged Re = 1600–18 000. Distinguishable peaks in PSD indicated a function of the resonator. Because the most effective acoustic response was found at higher Re, a majority of experiments focused on higher Re regime. The results demonstrate effects of the passive control on the jet behavior. Fluid mixing and velocity decay along the axis is intensified. It causes shortening of the jet transition region. On the other hand, an inverse proportionality of the velocity decay (u ~ 1/x in the fully developed region is not changed. The momentum and kinetic energy fluxes decrease more intensively in the controlled jets in comparison with common jets.
Kinetic extensions of magnetohydrodynamic models for axisymmetric toroidal plasmas
International Nuclear Information System (INIS)
Cheng, C.Z.
1989-04-01
A nonvariational kinetic-MHD stability code (NOVA-K) has been developed to integrate a set of non-Hermitian integro-differential eigenmode equations due to energetic particles for axisymmetric toroidal plasmas in a general flux coordinate system with an arbitrary Jacobian. The NOVA-K code employs the Galerkin method involving Fourier expansions in the generalized poloidal angle θ and generalized toroidal angle /zeta/ directions, and cubic-B spline finite elements in the radial /Psi/ direction. Extensive comparisons with the existing variational ideal MHD codes show that the ideal MHD version of the NOVA-K code converges faster and gives more accurate results. The NOVA-K code is employed to study the effects of energetic particles on MHD-type modes: the stabilization of ideal MHD internal kink modes and the excitation of ''fishbone'' internal kink modes; and the alpha particle destabilization of toroidicity-induced Alfven eigenmodes (TAE) via transit resonances. Analytical theories are also presented to help explain the NOVA-K results. For energetic trapped particles generated by neutral beam injection (NBI) or ion cyclotron resonant heating (ICRH), a stability window for the n = 1 internal kink mode in the hot particle beta space exists even in the absence of the core ion finite Larmor radius effect. On the other hand, the trapped alpha particles are found to have negligible effects on the stability of the n = 1 internal kink mode, but the circulating alpha particles can strongly destabilize TAE modes via inverse Landau damping associated with the spatial gradient of the alpha particle pressure. 60 refs., 24 figs., 1 tab
Detection of electromagnetic radiation using nonlinear materials
Hwang, Harold Y.; Liu, Mengkun; Averitt, Richard D.; Nelson, Keith A.; Sternbach, Aaron; Fan, Kebin
2016-06-14
An apparatus for detecting electromagnetic radiation within a target frequency range is provided. The apparatus includes a substrate and one or more resonator structures disposed on the substrate. The substrate can be a dielectric or semiconductor material. Each of the one or more resonator structures has at least one dimension that is less than the wavelength of target electromagnetic radiation within the target frequency range, and each of the resonator structures includes at least two conductive structures separated by a spacing. Charge carriers are induced in the substrate near the spacing when the resonator structures are exposed to the target electromagnetic radiation. A measure of the change in conductivity of the substrate due to the induced charge carriers provides an indication of the presence of the target electromagnetic radiation.
International Nuclear Information System (INIS)
Miller, J.S.
1987-01-01
An electromagnetic shield is described comprising: closed, electrically-conductive rings, each having an open center; and binder means for arranging the rings in a predetermined, fixed relationship relative to each other, the so-arranged rings and binder means defining an outer surface; wherein electromagnetic energy received by the shield from a source adjacent its outer surface induces an electrical current to flow in a predetermined direction adjacent and parallel to the outer surface, through the rings; and wherein each ring is configured to cause source-induced alternating current flowing through the portion of the ring closest to the outer surface to electromagnetically induce an oppositely-directed current in the portion of the ring furthest from the surface, such oppositely-directed current bucking any source-induced current in the latter ring portion and thus reducing the magnitude of current flowing through it, whereby the electromagnetic shielding effected by the shield is enhanced
Thomas, David T; Hartnett, James P; Hughes, William F
1973-01-01
The applications involving electromagnetic fields are so pervasive that it is difficult to estimate their contribution to the industrial output: generation of electricity, power transmission lines, electric motors, actuators, relays, radio, TV and microwave transmission and reception, magnetic storage, and even the mundane little magnet used to hold a paper note on the refrigerator are all electromagnetic in nature. One would be hard pressed to find a device that works without relaying on any electromagnetic principle or effect. This text provides a good theoretical understanding of the electromagnetic field equations but also treats a large number of applications. In fact, no topic is presented unless it is directly applicable to engineering design or unless it is needed for the understanding of another topic. In electrostatics, for example, the text includes discussions of photocopying, ink-jet printing, electrostatic separation and deposition, sandpaper production, paint spraying, and powder coating. In ma...
Multispecies transport theory for axisymmetric rotating plasmas
International Nuclear Information System (INIS)
Tessarotto, M.; White, R.B.
1992-01-01
A reduced gyrokinetic equation is derived for a multi-species toroidal axisymmetric plasma with arbitrary toroidal differential rotation speeds and in the presence of a finite induced electric field. The kinetic equation obtained, extending previous results obtained by Hinton and Wong and by Catto, Bernstein and Tessarotto, has a form suited for transport applications, via variational techniques; in particular it exhibits the feature that all source terms, including the Spitzer source term, carrying the contribution due to the inductive electric field, appear to be acted upon by the collision operator. Moreover, the equation displays a new contribution due to ''explicit'' velocity perturbations, here proven to be consistent with transport ordering, whose evaluation appears relevant for transport calculations. In addition, general expressions are obtained for the neoclassical fluxes in terms of a variational principle, as well as for the classical ones, retaining, in both cases, the contributions due to the Spitzer's inductive terms
A Compact Quasi-axisymmetric Stellarator Reactor
International Nuclear Information System (INIS)
Ku, L.P.
2003-01-01
We report the progress made in assessing the potential of compact, quasi-axisymmetric stellarators as power-producing reactors. Using an aspect ratio A=4.5 configuration derived from NCSX and optimized with respect to the quasi-axisymmetry and MHD stability in the linear regime as an example, we show that a reactor of 1 GW(e) maybe realizable with a major radius *8 m. This is significantly smaller than the designs of stellarator reactors attempted before. We further show the design of modular coils and discuss the optimization of coil aspect ratios in order to accommodate the blanket for tritium breeding and radiation shielding for coil protection. In addition, we discuss the effects of coil aspect ratio on the peak magnetic field in the coils
Electrostatic axisymmetric mirror with removable spherical aberration
International Nuclear Information System (INIS)
Birmuzaev, S.B.; Serikbaeva, G.S.; Hizirova, M.A.
1999-01-01
The electrostatic axisymmetric mirror, assembled from three coaxial cylinders with an equal diameter d and under the potential v1, v2 and v3, was computed. The proportions of geometrical and electric parameters of the mirror, with which the spherical 3-order aberration may be eliminated, were determined. The computation outcomes of the case, when the focal power of the mirror is enough large and the object plane in the focus is out of its field, are presented (Fig. 1 - potentials proportion that makes elimination of the spherical aberration possible; Fig. 2 - the focus coordinates when the spherical aberration is eliminated). The geometrical values are presented by d, and the electric ones are presented by v1. The figures on the curves present a length of the second (middle) electrode. The zero point is located in the middle of the gap between the first and second electrodes The investigated mirror may be used as a lens for the transmission electron microscope
Axisymmetric Eigenmodes of Spheroidal Pure Electron Plasmas
Kawai, Yosuke; Saitoh, Haruhiko; Yoshida, Zensho; Kiwamoto, Yasuhito
2010-11-01
The axisymmetric electrostatic eigenmodes of spheroidal pure electron plasmas have been studied experimentally. It is confirmed that the observed spheroidal plasma attains a theoretically expected equilibrium density distribution, with the exception of a low-density halo distribution surrounding the plasma. When the eigenmode frequency observed for the plasma is compared with the frequency predicted by the dispersion relation derived under ideal conditions wherein the temperature is zero and the boundary is located at an infinite distance from the plasma, it is observed that the absolute value of the observed frequency is systematically higher than the theoretical prediction. Experimental examinations and numerical calculations indicate that the upward shift of the eigenmode frequency cannot be accounted for solely by the finite temperature effect, but is significantly affected by image charges induced on the conducting boundary and the resulting distortion of the density profile from the theoretical expectation.
DEFF Research Database (Denmark)
Cermak, Daniel; Okutsu, Ayaka; Jørgensen, Stina Marie Hasse
2015-01-01
Daniel Cermak-Sassenrath, Ayaka Okutsu, Stina Hasse. Electromagnetic Landscape - In-between Signal, Noise and Environment. Installation and artist talk. 21th International Symposium on Electronic Art (ISEA) 2015, Vancouver, CAN, Aug 14-18, 2015.......Daniel Cermak-Sassenrath, Ayaka Okutsu, Stina Hasse. Electromagnetic Landscape - In-between Signal, Noise and Environment. Installation and artist talk. 21th International Symposium on Electronic Art (ISEA) 2015, Vancouver, CAN, Aug 14-18, 2015....
RAXBOD- INVISCID TRANSONIC FLOW OVER AXISYMMETRIC BODIES
Keller, J. D.
1994-01-01
The problem of axisymmetric transonic flow is of interest not only because of the practical application to missile and launch vehicle aerodynamics, but also because of its relation to fully three-dimensional flow in terms of the area rule. The RAXBOD computer program was developed for the analysis of steady, inviscid, irrotational, transonic flow over axisymmetric bodies in free air. RAXBOD uses a finite-difference relaxation method to numerically solve the exact formulation of the disturbance velocity potential with exact surface boundary conditions. Agreement with available experimental results has been good in cases where viscous effects and wind-tunnel wall interference are not important. The governing second-order partial differential equation describing the flow potential is replaced by a system of finite difference equations, including Jameson's "rotated" difference scheme at supersonic points. A stretching is applied to both the normal and tangential coordinates such that the infinite physical space is mapped onto a finite computational space. The boundary condition at infinity can be applied directly and there is no need for an asymptotic far-field solution. The system of finite difference equations is solved by a column relaxation method. In order to obtain both rapid convergence and any desired resolution, the relaxation is performed iteratively on successively refined grids. Input to RAXBOD consists of a description of the body geometry, the free stream conditions, and the desired resolution control parameters. Output from RAXBOD includes computed geometric parameters in the normal and tangential directions, iteration history information, drag coefficients, flow field data in the computational plane, and coordinates of the sonic line. This program is written in FORTRAN IV for batch execution and has been implemented on a CDC 6600 computer with an overlayed central memory requirement of approximately 40K (octal) of 60 bit words. Optional plotted output
Axisymmetric MHD stability of sharp-boundary Tokamaks
International Nuclear Information System (INIS)
Rebhan, E.; Salat, A.
1976-09-01
For a sharp-boundary, constant pressure plasma model of axisymmetric equilibria the MHD stability problem of axisymmetric perturbations is solved by analytic reduction to a one-dimensional problem on the boundary and subsequent numerical treatment, using the energy principle. The stability boundaries are determined for arbitrary aspect ratio, arbitrary βsub(p) and elliptical, triangular and rectangular plasma cross-sections, wall stabilization not being taken into account. It is found that the axisymmetric stability strongly depends on the plasma shape and is almost independent of the safety factor q. (orig.) [de
International Nuclear Information System (INIS)
Moon, Han Seb; Noh, Heung-Ryoul
2011-01-01
The polarization dependence of double-resonance optical pumping (DROP) in the ladder-type electromagnetically induced transparency (EIT) of the 5S 1/2 -5P 3/2 -5D 5/2 transition of 87 Rb atoms is studied. The transmittance spectra in the 5S 1/2 (F=2)-5P 3/2 (F'=3)-5D 5/2 (F''=2,3,4) transition were observed as caused by EIT, DROP, and saturation effects in the various polarization combinations between the probe and coupling lasers. The features of the double-structure transmittance spectra in the 5S 1/2 (F=2)-5P 3/2 (F'=3)-5D 5/2 (F''=4) cycling transition were attributed to the difference in saturation effect according to the transition routes between the Zeeman sublevels and the EIT according to the two-photon transition probability.
1981-08-17
Van Blaricum, "On the Source of Parameter Bias in Prony’s Method," 1980 NEM Conference, Disneyland Hotel, August 1980. Auton, J.R., "An Unbiased...Method for the Estimation of the SEM Parameters of an Electromagnetic System," 1980 NEM Conference, Disneyland Hotel, August 1980. Auton, J.R. and M.L...34 1980 NEM Conference, Disneyland Hotel, August 5-7, 1980. Chuang, C.W. and D.L. Moffatt, "Complex Natural Responances of Radar Targets via Prony’s
Engineering Design Study of Quasi-Axisymmetric Stellarator with Low Aspect Ratio
International Nuclear Information System (INIS)
Matsuoka, Keisuke; Okamura, Shoichi; Nishimura, Shin; Isobe, Mitsutaka; Suzuki, Chihiro; Shimizu, Akihiro; Tanaka, Nobuo; Hasegawa, Mitsuru; Naito, Hideji; Urata, Kazuhiro; Suzuki, Yutaka; Tsukamoto, Tadanori
2004-01-01
The engineering design of the quasi-axisymmetric stellarator CHS-qa is described, having a toroidal period number of 2, major radius of 1.5 m, and plasma aspect ratio of 3.2. Although the entire structure of the machine is highly nonaxisymmetric and deformative, the following major engineering concerns for the modular coils and the vacuum vessel have been resolved: (a) modular coil design (curvature and twist of conductors), (b) supporting structures for modular coils, (c) errors due to electromagnetic forces and misalignment in manufacturing processes (analysis shows that the magnetic surface is robust against such disturbances), (d) construction procedure for vacuum vessel and modular coils, and (e) ports for heating and diagnostics
Axisymmetric particle-in-cell simulations of diamagnetic-cavity formation in vacuum
International Nuclear Information System (INIS)
Gisler, G.
1989-01-01
Axisymmetric simulations of the expansion of a hot plasma suddenly introduced into a vacuum containing a weak magnetic field were performed using an electromagnetic particle-in-cell code. Both uniform and gradient fields have been used, with the simulation axis along the principle field direction. The formation of a diamagnetic cavity requires an initial plasma β > 1; as the expansion proceeds, β diminishes, and the field eventually recovers. The maximum spatial extent of the cavity and its duration can be obtained from simple dynamical considerations. Field-aligned ion acceleration behind the electron front is observed in all field geometries and strengths. In the case of expansion into a divergent field, the plasma is found to move down the field gradient by ambipolar diffusion. These simulations are relevant to active release experiments in the Earth's magnetosphere, to pellet ablation experiments, and to the naturally occurring diamagnetic bubbles observed at the Earth's foreshock
International Nuclear Information System (INIS)
Ito, Koji; Suetake, Norio; Aizawa, Toshie; Nakasaki, Masayoshi
1998-01-01
The present invention provides an electromagnetic pump suitable to a recycling pump for liquid sodium as coolants of an FBR type reactor. Namely, a stator module of the electromagnetic pump of the present invention comprises a plurality of outer laminate iron core units and outer stator modules stacked alternately in the axial direction. With such a constitution, even a long electromagnetic pump having a large number of outer stator coils can be manufactured without damaging electric insulation of the outer stator coils. In addition, the inner circumferential surface of the outer laminate iron cores is urged and brought into contact with the outer circumferential surface of the outer duct by an elastic material. With such a constitution, Joule loss heat generated in the outer stator coils and internal heat generated in the outer laminate iron cores can be released to an electroconductive fluid flowing the inner circumference of the outer duct by way of the outer duct. (I.S.)
Energy Technology Data Exchange (ETDEWEB)
Pophof, B. [Bundesamt fuer Strahlenschutz, Abteilung fuer Wirkungen und Risiken ionisierender und nichtionisierender Strahlung, Oberschleissheim/Neuherberg (Germany); Brix, G. [Bundesamt fuer Strahlenschutz, Abteilung fuer medizinischen und beruflichen Strahlenschutz, Oberschleissheim/Neuherberg (Germany)
2017-07-15
During the last few years, new studies on biological effects of strong static magnetic fields and on thermal effects of high-frequency electromagnetic fields used in magnetic resonance imaging (MRI) were published. Many of these studies have not yet been included in the current safety recommendations. Scientific publications since 2010 on biological effects of static and electromagnetic fields in MRI were researched and evaluated. New studies confirm older publications that have already described effects of static magnetic fields on sensory organs and the central nervous system, accompanied by sensory perceptions. A new result is the direct effect of Lorentz forces on ionic currents in the semicircular canals of the vestibular system. Recent studies of thermal effects of high-frequency electromagnetic fields were focused on the development of anatomically realistic body models and a more precise simulation of exposure scenarios. Strong static magnetic fields can cause unpleasant sensations, in particular, vertigo. In addition, they can influence the performance of the medical staff and thus potentially endanger the patient's safety. As a precaution, medical personnel should move slowly within the field gradient. High-frequency electromagnetic fields lead to an increase in the temperature of patients' tissues and organs. This should be considered especially in patients with restricted thermoregulation and in pregnant women and neonates; in these cases exposure should be kept as low as possible. (orig.) [German] In den letzten Jahren wurden neue Studien zu biologischen Wirkungen starker statischer Magnetfelder und zu thermischen Effekten hochfrequenter elektromagnetischer Feldern, wie sie bei der Magnetresonanztomographie (MRT) verwendet werden, publiziert. Viele dieser Studien sind noch nicht in aktuelle Sicherheitsempfehlungen eingeflossen. Wissenschaftliche Publikationen ab dem Jahr 2010 zur biologischen Wirkung statischer und elektromagnetischer Felder
Axisymmetric Magnetic Mirror Fusion-Fission Hybrid
Energy Technology Data Exchange (ETDEWEB)
Moir, R. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martovetsky, N. N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molvik, A. W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Ryutov, D. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Simonen, T. C. [Univ. of California, Berkeley, CA (United States)
2011-05-13
The achieved performance of the gas dynamic trap version of magnetic mirrors and today’s technology we believe are sufficient with modest further efforts for a neutron source for material testing (Q=P_{fusion}/P_{input}~0.1). The performance needed for commercial power production requires considerable further advances to achieve the necessary high Q>>10. An early application of the mirror, requiring intermediate performance and intermediate values of Q~1 are the hybrid applications. The Axisymmetric Mirror has a number of attractive features as a driver for a fusion-fission hybrid system: geometrical simplicity, inherently steady-state operation, and the presence of the natural divertors in the form of end tanks. This level of physics performance has the virtue of low risk and only modest R&D needed and its simplicity promises economy advantages. Operation at Q~1 allows for relatively low electron temperatures, in the range of 4 keV, for the DT injection energy ~ 80 keV. A simple mirror with the plasma diameter of 1 m and mirror-to-mirror length of 35 m is discussed. Simple circular superconducting coils are based on today’s technology. The positive ion neutral beams are similar to existing units but designed for steady state. A brief qualitative discussion of three groups of physics issues is presented: axial heat loss, MHD stability in the axisymmetric geometry, microstability of sloshing ions. Burning fission reactor wastes by fissioning actinides (transuranics: Pu, Np, Am, Cm, .. or just minor actinides: Np, Am, Cm, …) in the hybrid will multiply fusion’s energy by a factor of ~10 or more and diminish the Q needed to less than 1 to overcome the cost of recirculating power for good economics. The economic value of destroying actinides by fissioning is rather low based on either the cost of long-term storage or even deep geologic disposal so most of the revenues of hybrids will come from electrical power. Hybrids that obtain revenues from
Computational study of axisymmetric modes in noncircular cross section tokamaks
International Nuclear Information System (INIS)
Johnson, J.L.; Chance, M.S.; Greene, J.M.; Grimm, R.C.; Jardin, S.C.; Kerner, W.; Manickam, J.; Weimer, K.E.
1976-09-01
A major computational program to investigate the MHD equilibrium, stability, and nonlinear evolution properties of realistic tokamak configurations is proceeding. Preliminary application is made to the Princeton PDX device. Both axisymmetric (n = 0) modes and kink (n = 1) modes are found; the growth rates depend sensitively on the configuration. A study of the nonlinear evolution of axisymmetric modes in such a device shows that flux conservation in the vacuum region can limit their growth
Axisymmetric, Ventilated Supercavitation in Unsteady, Horizontal Flow
Kawakami, Ellison; Lee, Seung-Jae; Arndt, Roger
2012-11-01
Drag reduction and/or speed augmentation of marine vehicles by means of supercavitation is a topic of great interest. During the initial launch of a supercavitating vehicle, an artificial supercavity is required until the vehicle can reach conditions at which a natural supercavity can be sustained. Previous studies at Saint Anthony Falls Laboratory (SAFL) focused on the behavior of ventilated supercavities in steady horizontal flows. In open waters, vehicles can encounter unsteady flows, especially when traveling under waves. A study has been carried out at SAFL to investigate the effects of unsteady flow on axisymmetric supercavities. An attempt is made to duplicate sea states seen in open waters. In an effort to track cavity dimensions throughout a wave cycle, an automated cavity tracking script has been developed. Using a high speed camera and the proper software, it is possible to synchronize cavity dimensions with pressure measurements taken inside the cavity. Results regarding supercavity shape, ventilation demand, cavitation parameters and closure methods are presented. It was found that flow unsteadiness caused a decrease in the overall length of the supercavity while having only a minimal effect on the maximum diameter. The supercavity volume varied with cavitation number and a possible relationship between the two is being explored. (Supported by ONR)
Pressure anisotropy stabilization of axisymmetric mirror machines
International Nuclear Information System (INIS)
Weitzner, H.
1978-01-01
The stability of a two species, anisotropic pressure, axisymmetric plasma is studied using the guiding center plasma model. Successively, asymptotic expansions are applied appropriate to a long, thin plasma, and to a plasma with flux surfaces close to cylinders. The resultant stability problem may be cast as an ordinary differential equation eigenvalue problem or as a problem in the calculus of variations. It is shown that low beta plasmas cannot be confined and be stable although plasmas may be stable in which the pressure gradients are nonzero where the pressure tends to zero. Stable profiles are given; these profiles include the possibility of field reversed regions. These stable profiles require the anisotropic species to be cold near the axis. Rather than absolute stability, a weaker condition is also considered which for fixed azimuthal mode number vertical-barmvertical-bar puts the point of accumulation of the spectrum of modes on the stable side. It is hoped that such a condition may yield systems stable to vertical-barmvertical-bar small modes although not all values of vertical-barmvertical-bar. This condition is more readily satisfied and allows more reasonable profiles near the axis
A steady-state axisymmetric toroidal system
International Nuclear Information System (INIS)
Hirano, K.
1984-01-01
Conditions for achieving a steady state in an axisymmetric toroidal system are studied with emphasis on a very-high-beta field-reversed configuration. The analysis is carried out for the electromotive force produced by the Ohkawa current that is induced by neutral-beam injection. It turns out that, since the perpendicular component of the current j-vectorsub(perpendicular) to the magnetic field can be generated automatically by the diamagnetic effect, only the parallel component j-vectorsub(parallel) must be driven by the electromotive force. The drive of j-vectorsub(parallel) generates shear in the field line so that the pure toroidal field on the magnetic axis is rotated towards the plasma boundary and matched to the external field lines. This matching condition determines the necessary amount of injection beam current and power. It is demonstrated that a very-high-beta field-reversed configuration requires only a small amount of current-driving beam power because almost all the toroidal current except that close to the magnetic axis is carried by the diamagnetic current due to high beta. A low-beta tokamak, on the other hand, needs very high current-driving power since most of the toroidal current is composed of j-vectorsub(parallel) which must be driven by the beam. (author)
Discontinuities in an axisymmetric generalized thermoelastic problem
Directory of Open Access Journals (Sweden)
Moncef Aouadi
2005-06-01
Full Text Available This paper deals with discontinuities analysis in the temperature, displacement, and stress fields of a thick plate whose lower and upper surfaces are traction-free and subjected to a given axisymmetric temperature distribution. The analysis is carried out under three thermoelastic theories. Potential functions together with Laplace and Hankel transform techniques are used to derive the solution in the transformed domain. Exact expressions for the magnitude of discontinuities are computed by using an exact method developed by Boley (1962. It is found that there exist two coupled waves, one of which is elastic and the other is thermal, both propagating with finite speeds with exponential attenuation, and a third which is called shear wave, propagating with constant speed but with no exponential attenuation. The Hankel transforms are inverted analytically. The inversion of the Laplace transforms is carried out using the inversion formula of the transform together with Fourier expansion techniques. Numerical results are presented graphically along with a comparison of the three theories of thermoelasticity.
Axisymmetric plasma equilibria in a Kerr metric
Elsässer, Klaus
2001-10-01
Plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species. The quasi-neutrality assumption (no charge density, no toroidal current) allows to solve Maxwell's equations analytically for any axisymmetric stationary metric, and to reduce the fluid equations to one single scalar equation for the stream function \\chi of the positrons or ions, respectively. The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio m_e/m_i. The \\chi-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.
Axisymmetric Plasma Equilibria in General Relativity
Elsässer, Klaus
Axisymmetric plasma equilibria near a rotating black hole are considered within the multifluid description. An isothermal two-component plasma with electrons and positrons or ions is determined by four structure functions and the boundary conditions. These structure functions are the Bernoulli function and the toroidal canonical momentum per mass for each species; they remain arbitrary if no gain and loss processes are considered, in close analogy to the free flux functions in ideal magnetohydrodynamics. Several simplifying assumptions allow the reduction of the basic equations to one single scalar equation for the stream function χ of positrons or ions, respectively, playing the rôle of the Grad/Shafranov equation in magnetohydrodynamics; in particular, Maxwell's equations can be solved analytically for a quasineutral plasma when both the charge density and the toroidal electric current density are negligible (in contrast to the Tokamak situation). The basic smallness parameter is the ratio of the skin depth of electrons to the scale length of the metric and fluid quantities, and, in the case of an electron-ion plasma, the mass ratio me/mi. The χ-equation can be solved by standard methods, and simple solutions for a Kerr geometry are available; they show characteristic flow patterns, depending on the structure functions and the boundary conditions.
DEFF Research Database (Denmark)
Cermak, Daniel; Okutsu, Ayaka; Hasse, Stina
2015-01-01
Electromagnetic Landscape demonstrates in direct, tangible and immediate ways effects of the disruption of the familiar. An ubiquitous technological medium, FM radio, is turned into an alien and unfamiliar one. Audience participation, the environment, radio signals and noise create a site...
Broadband electromagnetic environments simulator (EMES)
International Nuclear Information System (INIS)
Pollard, N.
1977-01-01
A new test facility has been developed by Sandia Laboratories for determining the effects of electromagnetic environments on systems and components. The facility is capable of producing uniform, vertically polarized, continuous wave (CW) and pulsed fields over the frequency range of dc to 10 GHz. This broadband capability addresses the electromagnetic radiation (EMR) threat and is ideally suited to computer controlled sweeping and data acquisition. EMES is also capable of producing uniform transient fields having the wave shape and magnitude characteristic of a nuclear electromagnetic pulse (EMP) and near lightning. The design consists of a truncated, triplate, rectangular coaxial transmission line. The spacing between the flat center conductor and the ground planes is 4 meters. The line is terminated in its characteristic impedance of 50 ohms. At frequencies below the first resonance of the facility it behaves as a typical coaxial system. Above resonance, a wall of electromagnetic absorbing material provides a nonreflecting termination. Thus, EMES essentially combines the elements of a transmission line and an anechoic chamber. It will not radiate electromagnetic energy into the surrounding area because it is a shielded transmission line
A measurement device for electromagnetic flow tomography
Vauhkonen, M.; Hänninen, A.; Lehtikangas, O.
2018-01-01
Electromagnetic flow meters have succesfully been used in many industries to measure the mean flow velocity of conductive liquids. This technology works reliably in single phase flows with axisymmetric flow profiles but can be inaccurate with asymmetric flows, which are encountered, for example, in multiphase flows, pipe elbows and T-junctions. Some computational techniques and measurement devices with multiple excitation coils and measurement electrodes have recently been proposed to be used in cases of asymmetric flows. In earlier studies, we proposed a computational approach for electromagnetic flow tomography (EMFT) for estimating velocity fields utilizing several excitation coils and a set of measurement electrodes attached to the surface of the pipe. This approach has been shown to work well with simulated data but has not been tested extensively with real measurements. In this paper, an EMFT system with four excitation coils and 16 measurement electrodes is introduced. The system is capable of using both square wave and sinusoidal coil current excitations and all the coils can be excited individually, also enabling parallel excitations with multiple frequencies. The studies undertaken in the paper demonstrate that the proposed EMFT system, together with the earlier introduced velocity field reconstruction approach, is capable of producing reliable velocify field estimates in a laboratory environment with both axisymmetric and asymmetric single phase flows.
Electromagnetic radiation unmasked
International Nuclear Information System (INIS)
Hart, P.
1996-01-01
This article describes the nature of the electromagnetic waves, what they are and how do they affect us. Current concern is focused on exposure to low level power-frequency magnetic fields like microwave radiation from mobile phones and leaking microwave ovens; high power radiation from defence and airport radars; fields close to high voltage transmission lines; radio frequency fields from industrial welders and heaters and DC magnetic fields in aluminium smelters. These fields with frequency less than 300 GHz do not carry sufficient energy to break chemical bonds and it is assumed that they cannot damage cell DNA. The amount of radiation absorbed by a human exposed to far field electromagnetic radiation (EMR) depends on the orientation and size of the person. In the 30-300 MHz range it is possible to excite resonance in the whole or partial body such as the head. It is emphasised that since there are some evidence that electromagnetic fields do harm, a policy of prudent avoidance is recommended, especially for children. ills
International Nuclear Information System (INIS)
Zheng, Jinxing; Song, Yuntao; Breslau, Joshua; Neilson, George Hutch
2014-01-01
Highlights: • Systematic studies of modular coils characteristics for quasi-axisymmetric stellarator were carried out for the key design parameters. • We systematically analyzed the relationships between design parameters of modular coils and electromagnetic properties such as the maximum field. • The approximate formulae relating modular coil parameters to the maximum magnetic field were derived by the use of simple two coil systems. - Abstract: Modular coil characteristics of a 2-field periods quasi-axisymmetric stellarator QAS-LA configuration with an aspect ratio A p = 3, magnetic pressure ∼4% and rotational transform ι ∼ 0.15 per field period supplied by its own shaping have been detailed studied. In addition, the characteristics of modular coils for QAS-LA were compared with those of an intermediate QA configuration QAS-LAx and a tokamak based on the same center magnet field B 0 , aspect ratio and number of coils. As expected, the B max /B 0 , force F and overturning moment M, increase with the increased complexity of the coil shape. The relationships between the modular coils’ parameters (such as radius curvature ρ, distance from coil to coil Δ c–c and the cross-section of coils) and the electromagnetic characteristics have been systematically summarized. The approximate formula for the maximum magnetic field in the coil body as functions of modular coil parameters (Δ c–c , ρ) was derived for a simple two wire system which will be useful when optimizations of coil properties are called for
International Nuclear Information System (INIS)
2009-01-01
The investigating committee aimed at research on electromagnetic fields in functional devices and X-ray fibers for efficient coherent X-ray generation and their material science, high-precision manufacturing, X-ray microscope, application to medical and information communication technologies, such as interaction between material and nanometer electromagnetic waves of radiated light and X-ray, interaction between microwaves and particle beams, theory and design of high-frequency waveguides for resonator and accelerator, from January 2003 to December 2005. In this report, we describe our research results, in particular, on the topics of synchrotron radiation and Cherenkov radiation, Kyushu synchrotron light source and its technology, nanometer electromagnetic fields in optical region, process of interaction between evanescent waves and near-field light, orthogonal relation of electromagnetic fields including evanescent waves in dispersive dielectrics, optical amplification using electron beam, nanometer electromagnetic fields in focusing waveguide lens device with curved facets, electromagnetic fields in nanometer photonic crystal waveguide consisting of atoms, X-ray scattering and absorption I bio-material for image diagnosis. (author)
International Nuclear Information System (INIS)
Tzeng, Wen-Shian V.
1991-01-01
Electromagnetic interference (EMI) shielding materials are well known in the art in forms such as gaskets, caulking compounds, adhesives, coatings and the like for a variety of EMI shielding purposes. In the past, where high shielding performance is necessary, EMI shielding has tended to use silver particles or silver coated copper particles dispersed in a resin binder. More recently, aluminum core silver coated particles have been used to reduce costs while maintaining good electrical and physical properties. (author). 8 figs
Energy Technology Data Exchange (ETDEWEB)
Aldridge, David F.
2014-11-01
A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories
Ida, Nathan
2015-01-01
This book provides students with a thorough theoretical understanding of electromagnetic field equations and it also treats a large number of applications. The text is a comprehensive two-semester textbook. The work treats most topics in two steps – a short, introductory chapter followed by a second chapter with in-depth extensive treatment; between 10 to 30 applications per topic; examples and exercises throughout the book; experiments, problems and summaries. The new edition includes: updated end of chapter problems; a new introduction to electromagnetics based on behavior of charges; a new section on units; MATLAB tools for solution of problems and demonstration of subjects; most chapters include a summary. The book is an undergraduate textbook at the Junior level, intended for required classes in electromagnetics. It is written in simple terms with all details of derivations included and all steps in solutions listed. It requires little beyond basic calculus and can be used for self-study. The weal...
Electromagnetic aquametry electromagnetic wave interaction with water and moist substances
Kupfer, Klaus
2006-01-01
This book covers all aspects of Electromagnetic Aquametry. It summarizes the wide area of metrology and its applications in electromagnetic sensing of moist materials. The physical properties of water in various degrees of binding interacting with electromagnetic fields is presented by model systems. The book describes measurement methods and sensors in the frequency domain, TDR-techniques for environmental problems, methods and sensors for quality assessment of biological substances, and nuclear magnetic resonance techniques. Environmental sciences, as well as civil and geoengineering, fossil fuels, food and pharmaceutical science are the main fields of application. A very wide frequency sprectrum is used for dielectric measurement methods, but the microwave range is clearly dominant. Multiparameter methods as well as methods of principal components and artificial neural networks for density independent measurements are described.
International Nuclear Information System (INIS)
Lefevre, Thibaut
2000-01-01
The next generation of electron-positron linear colliders must reach the TeV energy range. For this, one requires an adequate RF power source to feed the accelerating cavities of the collider. One way to generate this source is to use the Two Beam Accelerator concept in which the RF power is produced in resonant cavities driven by an intense bunched beam. In this thesis, I present the experimental results obtained at the CEA/CESTA using an electron beam generated by an induction linac. First, some studies were performed with the LELIA induction linac (2.2 MeV, 1 kA, 80 ns) using a Free Electron Laser (FEL) as a buncher at 35 GHz. A second part relates the experiment made with the PIVAIR induction linac (7 MeV, 1 kA, 80 ns) in order to measure the RF power extracted from a resonant cavity at 35 GHz, which is driven by the bunches produced in the FEL. One can also find a simple theoretical modeling of the beam-cavity interaction, and the numerical results dealing with the design of the cavity we tested. (author) [fr
Theoretical analysis of the vibration of axisymmetric liquid bridges of arbitrary shape
Energy Technology Data Exchange (ETDEWEB)
Montanero, J.M. [Departamento de Electronica e Ingenieria Electromecanica, Universidad de Extremadura, 06071 Badajoz (Spain)
2003-01-01
A liquid bridge consists of a mass of liquid sustained by the action of capillary forces between two parallel disks. The dynamics of these liquid columns has been extensively analysed both theoretically and experimentally over the last decades. Many of the studies have focused on the dynamical response of cylindrical liquid bridges subjected to the action of an oscillatory microgravity field due to, for instance, an in-phase vibration of the supporting disks. There have been fewer studies dealing with the vibration of axisymmetric liquid bridges of arbitrary shape. In this paper the dynamics of rotating inviscid axisymmetric liquid bridges is analysed considering the combined effect of residual gravity, the inequality of the disks and the liquid bridge volume. The results are calculated numerically by using the one-dimensional Cosserat model and the full three-dimensional description. The excitation is assumed to be of small amplitude and harmonic, so that the theoretical models are linearized and the analysis is performed in the frequency domain. The details of the numerical methods proposed are discussed. Comparison between the values of the first resonance frequency obtained from both models shows an excellent agreement for long liquid bridges, the discrepancies increasing as the value of the slenderness decreases. (orig.)
A new periodic imperfect quasi axisymmetric shell element
International Nuclear Information System (INIS)
Combescure, A.; Garuti, G.
1983-08-01
The object of this paper is to give the formulation and the validation of a ''quasi axisymmetric'' shell element: the main idea is to develop the theory of an imperfect quasi axisymmetric shell element. The imperfection is a variation of the circumferential radius of curvature rsub(theta). The equations are obtained by transporting the equilibrium equations from the actual geometry onto the theoretical axisymmetric (rsub(theta)=r 0 geometry. It is shown that the main hypothesis convenient to perform simply this transformation is that the membrane strains associated with that variation of geometry are less than 1% (that is always the case if you suppose that the imperfect structure is obtained from the perfect one by an inextensional displacement field). The formulation of the element is given in the general case. The rigidity matrices, are given in the particular case in which the imperfection has a component on a single Fourier harmonic. The comparison of theoretical and computed, 3D and quasi axisymmetric, solution or a very simple case shows the influence of the number of the Fourier harmonics chosen on the response of the structure. The influence of the initial imperfections on the natural frequency are studied with element and compared with 3D calculations. Comparison of 3D, quasi axisymmetric, and analytical buckling loads are given and explained. This element gives a very efficient tool for the calculation of thin shells of revolution (which are always imperfect) and especially unables easy parametric study of the variation of the buckling load and eigen frequencies with the amplitude and shapes of non axisymmetric imperfections
Structures, systems and methods for harvesting energy from electromagnetic radiation
Novack, Steven D [Idaho Falls, ID; Kotter, Dale K [Shelley, ID; Pinhero, Patrick J [Columbia, MO
2011-12-06
Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.
Energy harvesting devices for harvesting energy from terahertz electromagnetic radiation
Novack, Steven D.; Kotter, Dale K.; Pinhero, Patrick J.
2012-10-09
Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.
Integrable motion of a vortex dipole in an axisymmetric flow
International Nuclear Information System (INIS)
Sutyrin, G.G.; Perrot, X.; Carton, X.
2008-01-01
The evolution of a self-propelling vortex dipole, embedded in an external nondivergent flow with constant potential vorticity, is studied in an equivalent-barotropic model commonly used in geophysical, astrophysical and plasma studies. In addition to the conservation of the Hamiltonian for an arbitrary point vortex dipole, it is found that the angular momentum is also conserved when the external flow is axisymmetric. This reduces the original four degrees of freedom to only two, so that the solution is expressed in quadratures. In particular, the scattering of antisymmetric dipoles approaching from the infinity is analyzed in the presence of an axisymmetric oceanic flow typical for the vicinity of isolated seamounts
International Nuclear Information System (INIS)
Burch, Aidan
2004-01-01
Working within the HPO (History Projection Operator) Consistent Histories formalism, we follow the work of Savvidou on (scalar) field theory [J. Math. Phys. 43, 3053 (2002)] and that of Savvidou and Anastopoulos on (first-class) constrained systems [Class. Quantum Gravt. 17, 2463 (2000)] to write a histories theory (both classical and quantum) of Electromagnetism. We focus particularly on the foliation-dependence of the histories phase space/Hilbert space and the action thereon of the two Poincare groups that arise in histories field theory. We quantize in the spirit of the Dirac scheme for constrained systems
Electromagnetic production of associated strangeness
Energy Technology Data Exchange (ETDEWEB)
David, J C [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee; Fayard, C; Lamot, G H [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Saghai, B [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee
1996-04-01
A formalism, based on an isobaric approach using Feynman diagram techniques, which includes the nucleonic (spin {<=} 5/2), hyperonic (spin 1/2) and kaonic resonances, is developed. Using this formalism, a thorough investigation of electromagnetic strangeness processes is performed. A reaction mechanism, describing well enough the data, is found to include a reasonable number of baryonic resonances among a very large number of potential candidates. Predictions for the upcoming photoproduction polarization and electroproduction observables are presented, and their sensitivity to the phenomenological models ingredients are emphasized. (K.A.). 70 refs.; Submitted to Physical Review, C (US).
Electromagnetic production of associated strangeness
International Nuclear Information System (INIS)
David, J.C.; CEA Centre d'Etudes de Saclay, 91 - Gif-sur-Yvette; Fayard, C.; Lamot, G.H.; Saghai, B.
1996-04-01
A formalism, based on an isobaric approach using Feynman diagram techniques, which includes the nucleonic (spin ≤ 5/2), hyperonic (spin 1/2) and kaonic resonances, is developed. Using this formalism, a thorough investigation of electromagnetic strangeness processes is performed. A reaction mechanism, describing well enough the data, is found to include a reasonable number of baryonic resonances among a very large number of potential candidates. Predictions for the upcoming photoproduction polarization and electroproduction observables are presented, and their sensitivity to the phenomenological models ingredients are emphasized. (K.A.)
International Nuclear Information System (INIS)
Pivovarov, Yu.L.; Shirokov, A.A.; Vorobiev, S.A.
1990-01-01
The energy dependence of electromagnetic excitation and electromagnetic disintegration cross sections for relativistic nuclei passing through crystals is investigated both theoretically and by means of computer simulation. For electromagnetic excitation, resonant peaks are found at definite energy values. An increase of electromagnetic excitation and disintegration cross sections in crystals at very high energies is found to be due to coherent addition of amplitudes. Numerical results are presented for the electric dipole excitation of fluorine nuclei and electromagnetic deuteron disintegration. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Dreicer, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1968-07-01
The motion of an electron orbiting under the combined action of a static magnetic field and the AC azimuthal electric field of a cylindrical TE{sub 011} mode is analyzed with help of a perturbation technique. The first and second order perturbation results indicate that at cyclotron resonance the electron's center of gyration oscillates slowly at right angles to the magnetic field between two turning points. We find that superimposed upon this nearly static Exb drift the electron cyclically undergoes the process of cyclotron absorption and induced emission. Our results indicate that it is possible to insure maser action (i.e. induced emission rather than absorption) without special preparation of the electron's velocity provided that the electron is introduced into the field in certain special regions of space pervaded by the TE mode. This is a case where over-population of the upper state is accomplished through 'pumping' in real space. The relation between an electron cyclotron resonance maser based upon this principle and one based upon the principle of velocity space pumping, due to Twiss, is examined. This treatment provides physical interpretations and verifies the numerical results found earlier by Le Gardeur. (author) [French] Le mouvement d'un electron soumis a l'action combinee d'un champ magnetique statique et d'un champ electrique haute frequence azimutal engendre dans une cavite cylindrique en mode TE{sub 011} est analyse a partir d'une methode de perturbation. Les resultats des perturbations au premier et deuxieme ordre indiquent qu'a la resonance cyclotronique, le centre de giration de l'electron oscille lentement dans le plan perpendiculaire au champ magnetique entre deux points de rebroussement. En plus de la derivee quasi-statique ExB, l'electron passe par des etats d'absorption et emission cyclotronique. Les resultats du calcul confirment la possibilite d'avoir une action maser (c'est-a-dire: emission au lieu d'absorption) sans que la vitesse des
Energy Technology Data Exchange (ETDEWEB)
Massarczyk, Ralph Jens
2011-01-17
During the last hundred years several models were developed to describe the configuration of nuclei. These models have to make predictions, which should be comparable with experiments. As a standard type of experiment the nuclear resonance fluorescence was established. A nucleus is excited by irradiation with photons. By emitting one or more photons the nucleus decays back to the ground state. With this method it is possible to measure energy levels and to determine the strength of their excitation. A continuum of unresolved peaks gives additional strength. The existing setup at the linear electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf uses bremsstrahlung, produced as a secondary beam in a thin Niobium foil. During the years 2008/09 experiments on the nuclei of {sup 86}Kr and {sup 136}Ba took place there. In this work they will be analyzed. Photon flux and efficiency determination have been done as well as simulations on detector response and non-nuclear scattered background events. For this purpose the GEANT4 package was used. Finally the resulting cross sections were corrected for branching and feeding.
Parametric resonance in acoustically levitated water drops
International Nuclear Information System (INIS)
Shen, C.L.; Xie, W.J.; Wei, B.
2010-01-01
Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.
Parametric resonance in acoustically levitated water drops
Energy Technology Data Exchange (ETDEWEB)
Shen, C.L.; Xie, W.J. [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China); Wei, B., E-mail: bbwei@nwpu.edu.c [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)
2010-05-10
Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.
Axisymmetric Lattice Boltzmann Model of Droplet Impact on Solid Surfaces
Dalgamoni, Hussein; Yong, Xin
2017-11-01
Droplet impact is a ubiquitous fluid phenomena encountered in scientific and engineering applications such as ink-jet printing, coating, electronics manufacturing, and many others. It is of great technological importance to understand the detailed dynamics of drop impact on various surfaces. The lattice Boltzmann method (LBM) emerges as an efficient method for modeling complex fluid systems involving rapidly evolving fluid-fluid and fluid-solid interfaces with complex geometries. In this work, we model droplet impact on flat solid substrates with well-defined wetting behavior using a two-phase axisymmetric LBM with high density and viscosity contrasts. We extend the two-dimensional Lee and Liu model to capture axisymmetric effect in the normal impact. First we compare the 2D axisymmetric results with the 2D and 3D results reported by Lee and Liu to probe the effect of axisymmetric terms. Then, we explore the effects of Weber number, Ohnesorge number, and droplet-surface equilibrium contact angle on the impact. The dynamic contact angle and spreading factor of the droplet during impact are investigated to qualitatively characterize the impact dynamics.
Axisymmetric free convection boundary-layer flow past slender bodies
Kuiken, H.K.
1968-01-01
Radial curvature effects on axisymmetric free convection boundary-layer flow are investigated for vertical cylinders and cones for some special non-uniform temperature differences between the surface and the ambient fluid. The solution is given as a power series expansion, the first term being equal
Vortical motion in the head of an axisymmetric gravity current
Patterson, M.D.; Simpson, J.E.; Dalziel, S.B.; Heijst, van G.J.F.
2006-01-01
A series of experiments that examine the initial development of an axisymmetric gravity current have been carried out. The experiments highlight the growth of a ring vortex that dominates the dynamics of the gravity current's early time propagation. In particular, the experiments show three distinct
The shape of an axisymmetric bubble in uniform motion
Indian Academy of Sciences (India)
Axisymmetric bubble shapes; non-linear free boundary problems; surface singularity methods in potential flows. PACS Nos 47.55.Dz; 47.11.+j; 47.15.Hg. 1. .... should be fast and reasonably accurate, (c) the iterative procedure for determining .... curve while K2 is the other associated principal curvature; K2 can be deduced.
Edge Plasma Response to Non-Axisymmetric Fields in Tokamaks
Energy Technology Data Exchange (ETDEWEB)
Ferraro, N. M.; Lao, L. L.; Buttery, R. J.; Evans, T. E.; Snyder, P. B.; Wade, M.R., E-mail: ferraro@fusion.gat.com [General Atomics, San Diego (United States); Moyer, R. A.; Orlov, D. M. [University of California San Diego, La Jolla (United States); Lanctot, M. J. [Lawrence Livermore National Laboratory, Livermore (United States)
2012-09-15
Full text: The application of non-axisymmetric fields is found to have significant effects on the transport and stability of H-mode tokamak plasmas. These effects include dramatic changes in rotation and particle transport, and may lead to the partial or complete suppression of edge-localized modes (ELMs) under some circumstances. The physical mechanism underlying these effects is presently not well understood, in large part because the response of the plasma to non- axisymmetric fields is significant and complex. Here, recent advances in modeling the plasma response to non-axisymmetric fields are discussed. Calculations using a resistive two-fluid model in diverted toroidal geometry confirm the special role of the perpendicular electron velocity in suppressing the formation of islands in the plasma. The possibility that islands form near the top of the pedestal, where the zero-crossing of the perpendicular electron velocity may coincide with a mode-rational surface, is explored, and the implications for ELM suppression are discussed. Modeling results are compared with empirical data. It is shown that numerical modeling is successful in reproducing some experimentally observed effects of applied non-axisymmetric fields on the edge temperature and density profiles. The numerical model self-consistently includes the plasma, separatrix, and scrape-off layer. Rotation and diamagnetic effects are also included self-consistently. Solutions are calculated using the M3D-C1 extended-MHD code. (and others)
Modelling axisymmetric cod-ends made of different mesh types
DEFF Research Database (Denmark)
Priour, D.; Herrmann, Bent; O'Neill, F.G.
2009-01-01
the selectivity process has become more important. This paper presents a model of the deformation of an axisymmetric cod-end. The twine tension and the catch pressure acting on the knots of each mesh along the cod-end profile are calculated, and a Newton-Raphson scheme is used to estimate the equilibrium position...
Decay of passive scalar fluctuations in axisymmetric turbulence
Yoshimatsu, Katsunori; Davidson, Peter A.; Kaneda, Yukio
2016-11-01
Passive scalar fluctuations in axisymmetric Saffman turbulence are examined theoretically and numerically. Theoretical predictions are verified by direct numerical simulation (DNS). According to the DNS, self-similar decay of the turbulence and the persistency of the large-scale anisotropy are found for its fully developed turbulence. The DNS confirms the time-independence of the Corrsin integral.
Numerical computation of gravitational field for general axisymmetric objects
Fukushima, Toshio
2016-10-01
We developed a numerical method to compute the gravitational field of a general axisymmetric object. The method (I) numerically evaluates a double integral of the ring potential by the split quadrature method using the double exponential rules, and (II) derives the acceleration vector by numerically differentiating the numerically integrated potential by Ridder's algorithm. Numerical comparison with the analytical solutions for a finite uniform spheroid and an infinitely extended object of the Miyamoto-Nagai density distribution confirmed the 13- and 11-digit accuracy of the potential and the acceleration vector computed by the method, respectively. By using the method, we present the gravitational potential contour map and/or the rotation curve of various axisymmetric objects: (I) finite uniform objects covering rhombic spindles and circular toroids, (II) infinitely extended spheroids including Sérsic and Navarro-Frenk-White spheroids, and (III) other axisymmetric objects such as an X/peanut-shaped object like NGC 128, a power-law disc with a central hole like the protoplanetary disc of TW Hya, and a tear-drop-shaped toroid like an axisymmetric equilibrium solution of plasma charge distribution in an International Thermonuclear Experimental Reactor-like tokamak. The method is directly applicable to the electrostatic field and will be easily extended for the magnetostatic field. The FORTRAN 90 programs of the new method and some test results are electronically available.
Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry
Energy Technology Data Exchange (ETDEWEB)
Long-Poe Ku and Allen H. Boozer
2009-06-05
If quasi-axisymmetry is preserved, non-axisymmetric shaping can be used to design tokamaks that do not require current drive, are resilient to disruptions, and have robust plasma stability without feedback. Suggestions for addressing the critical issues of tokamaks can only be validated when presented with sufficient specificity that validating experiments can be designed. The purpose of this paper is provide that specificity for non-axisymmetric shaping. To our knowledge, no other suggestions for the solution of a number of tokamak issues, such as disruptions, have reached this level of specificity. Sequences of three-field-period quasi-axisymmetric plasmas are studied. These sequences address the questions: (1) What can be achieved at various levels of non-axisymmetric shaping? (2) What simplifications to the coils can be achieved by going to a larger aspect ratio? (3) What range of shaping can be achieved in a single experimental facility? The sequences of plasmas found in this study provide a set of interesting and potentially important configurations.
Elastic metamaterials for tuning circular polarization of electromagnetic waves.
Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A
2016-06-20
Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.
Electromagnetic topology: Characterization of internal electromagnetic coupling
Parmantier, J. P.; Aparicio, J. P.; Faure, F.
1991-01-01
The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.
Electromagnetically shielded building
International Nuclear Information System (INIS)
Takahashi, T.; Nakamura, M.; Yabana, Y.; Ishikawa, T.; Nagata, K.
1992-01-01
This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs
Electromagnetically shielded building
Energy Technology Data Exchange (ETDEWEB)
Takahashi, T; Nakamura, M; Yabana, Y; Ishikawa, T; Nagata, K
1992-04-21
This invention relates to a building having an electromagnetic shield structure well-suited for application to an information network system utilizing electromagnetic waves, and more particularly to an electromagnetically shielded building for enhancing the electromagnetic shielding performance of an external wall. 6 figs.
Electromagnetic Compatibility of Devices on Hybrid Electromagnetic Components
Konesev, S. G.; Khazieva, R. T.; Kirillov, R. V.; Gainutdinov, I. Z.; Kondratyev, E. Y.
2018-01-01
There is a general tendency to reduce the weight and dimensions, the consumption of conductive and electrical insulating materials, increase the reliability and energy efficiency of electrical devices. In recent years, designers have been actively developing devices based on hybrid electromagnetic components (HEMC) such as inductive-capacitive converters (ICC), voltages pulse generators (VPG), secondary power supplies (SPS), capacitive storage devices (CSD), induction heating systems (IHS). Sources of power supplies of similar electrical devices contain, as a rule, links of increased frequency and function in key (pulse) modes, which leads to an increase in electromagnetic interference (EMI). Nonlinear and periodic (impulse) loads, non-sinusoidal (pulsation) of the electromotive force and nonlinearity of the internal parameters of the source and input circuits of consumers distort the shape of the input voltage lead to an increase in thermal losses from the higher harmonic currents, aging of the insulation, increase in the weight of the power supply filter units, resonance at higher harmonics. The most important task is to analyze the operation of electrotechnical devices based on HEMC from the point of view of creating EMIs and assessing their electromagnetic compatibility (EMC) with power supply systems (PSS). The article presents the results of research on the operation of an IHS, the operation principle of a secondary power supply source of which is based on the operation of a half-bridge autonomous inverter, the switching circuit of which is made in the form of a HEMC, called the «multifunctional integrated electromagnetic component»" (MIEC).
Kolm, H.; Mongeau, P.; Williams, F.
1980-09-01
Recent advances in energy storage, switching and magnet technology make electromagnetic acceleration a viable alternative to chemical propulsion for certain tasks, and a means to perform other tasks not previously feasible. Applications include the acceleration of gram-size particles for hypervelocity research and the initiation of fusion by impact, a replacement for chemically propelled artillery, the transportation of cargo and personnel over inaccessible terrain, and the launching of space vehicles to supply massive space operations, and for the disposal of nuclear waste. The simplest launcher of interest is the railgun, in which a short-circuit slide or an arc is driven along two rails by direct current. The most sophisticated studied thus far is the mass driver, in which a superconducting shuttle bucket is accelerated by a line of pulse coils energized by capacitors at energy conversion efficiencies better than 90%. Other accelerators of interest include helical, brush-commutated motors, discrete coil arc commutated drivers, flux compression momentum transformers, and various hybrid electrochemical devices.
Topological Foundations of Electromagnetism
Barrett, Terrence W
2008-01-01
Topological Foundations of Electromagnetism seeks a fundamental understanding of the dynamics of electromagnetism; and marshals the evidence that in certain precisely defined topological conditions, electromagnetic theory (Maxwell's theory) must be extended or generalized in order to provide an explanation and understanding of, until now, unusual electromagnetic phenomena. Key to this generalization is an understanding of the circumstances under which the so-called A potential fields have physical effects. Basic to the approach taken is that the topological composition of electromagnetic field
Electromagnetic solitary waves in magnetized plasmas
International Nuclear Information System (INIS)
Hazeltine, R.D.; Holm, D.D.; Morrison, P.J.
1985-03-01
A Hamiltonian formulation, in terms of noncanonical Poisson bracket, is presented for a nonlinear fluid system that includes reduced magnetohydrodynamics and the Hasegawa-Mima equation as limiting cases. The single-helicity and axisymmetric versions possess three nonlinear Casimir invariants, from which a generalized potential can be constructed. Variation of the generalized potential yields a description of exact nonlinear stationary states. The new equilibria, allowing for plasma flow as well as partial electron adiabaticity, are distinct from those found in conventional magnetohydrodynamic theory. They differ from electrostatic stationary states in containing plasma current and magnetic field excitation. One class of steady-state solutions is shown to provide a simple electromagnetic generalization of drift-solitary waves
Disentanglement of Electromagnetic Baryon Properties
Sadasivan, Daniel; Doring, Michael
2017-01-01
Through recent advances in experimental techniques, the precise extraction of the spectrum of baryonic resonances and their properties becomes possible. Helicity couplings at the resonance pole are fundamental parameters describing the electromagnetic properties of resonances and enabling the comparison of theoretical models with data. We have extracted them from experiments carried out at Jefferson Lab and other facilities using a multipole analysis within the Julich-Bonn framework. Special attention has been paid to the uncertainties and correlations of helicity couplings. Using the world data on the reaction γp -> ηp , we have calculated, for the first time, the covariance matrix. Our results are useful in several ways. They quantify uncertainties but also correlations of helicity couplings. Second, they can tell us quantitatively how useful a given polarization measurement is. Third, they can tell us how the measurement of a new observable would constrain and disentangle the resonance properties which could be helpful in the design of new experiments. Finally, on the subject of the missing resonance problem, model selection techniques and statistical tests allow us to quantify the significance of whether a resonance exists. Supported by NSF CAREER Grant No. PHY-1452055, NSF PIF Grant No. 1415459, by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, and by Research Center Julich through the HPC grant jikp07.
Axisymmetric instability in a noncircular tokamak: experiment and theory
International Nuclear Information System (INIS)
Lipschultz, B.; Prager, S.C.; Todd, A.M.M.; Delucia, J.
1979-09-01
The stability of dee, inverse-dee and square cross section plasmas to axisymmetric modes has been investigated experimentally in Tokapole II, a tokamak with a four-null poloidal divertor. Experimental results are closely compared with predictions of two numerical stability codes -- the PEST code (ideal MHD, linear stability) adapted to tokapole geometry and a code which follows the nonlinear evolution of shapes similar to tokapole equilibria. Experimentally, the square is vertically stable and both dee's unstable to a vertical nonrigid axisymmetric shift. The central magnetic axis displacement grows exponentially with a growth time approximately 10 3 poloidal Alfven times plasma time. Proper initial positioning of the plasma on the midplane allows passive feedback to nonlinearly restore vertical motion to a small stable oscillation. Experimental poloidal flux plots are produced directly from internal magnetic probe measurements
Experimental and numerical research on cavitating flows around axisymmetric bodies
International Nuclear Information System (INIS)
Haipeng, Wei; Song, Fu; Qin, Wu; Biao, Huang; Guoyu, Wang
2014-01-01
We investigated the cavitating flows around different axisymmetric bodies based on experiments and numerical simulation. In the numerical simulation, the multiphase Reynolds averaged Navier Stokes equations (RANS) were solved via the commercial computational fluid dynamics code CFX. The modified k-wSST turbulence model was used along with the transport equation-based cavitation model. In the experiments, a high-speed video technique was used to observe the unsteady cavitating flow patterns, and the dynamic force measurement system was used to measure the hydrodynamics of the axisymmetric bodies under different cavitation conditions. Results are shown for the hemisphere bodies, conical bodies and blunt bodies. Reasonable agreements were obtained between the computational and experimental results. The results show that for the hemispherical body, the cavity consists of quasi-steady transparent region and unsteady foggy water-vapor mixture region, which contains small-scale vortices and is dominated by bubble clusters, causing irregular disturbances at the cavity interfaces. The curvature at the front of the conical body is larger, resulting in that the flow separates at the shoulder of the axisymmetric body. The cavity stretches downstream and reaches to a fixed cavity length and shape. For blunt bodies, the incipient cavitation number is larger than that for the hemispherical body. A large cloud cavity is formed at the shoulder of the blunt body in the cores of vortices in high shear separation regions and the re-entrant jet does not significantly interact with the cavity interface when it moves upstream. As to the dynamic characteristics of unsteady cavitating flows around the axisymmetric bodies, the pulsation frequency for the hemispherical body is larger than that for the blunt body. For the hemispherical body, the pulsation is mainly caused by the high-frequency, small-scale shedding at the rear end of the cavity, while for the blunt body, the main factor for
Nonconforming axisymmetric elements for the analysis of containment structures
International Nuclear Information System (INIS)
Choi, C.K.; Kim, S.Y.
1989-01-01
In this study, the behaviors of the conforming isoparametric quadrilateral 4-node and triangular 3-nod axisymmetric solid elements are improved by adding nonconforming displacement modes. The convergence tests and the irregular mesh tests have been established through the analyses of a primary shield wall typed structure. For example study, a containment wall with internal pressure of 60 ksi has been analyzed. It shows that the nonconforming elements behave better than the conforming elements, especially, in the structurally discontinuous regions
Axisymmetric MHD equilibrium solver with bicubic Hermite elements
International Nuclear Information System (INIS)
Luetjens, H.; Bondeson, A.; Roy, A.
1990-05-01
A numerical code solving axisymmetric magnetohydrodynamic equilibria with rectangular bicubic Hermite elements has been developed. Two test cases are used for checking the convergence rate of the solution. The mapping of the equilibrium quantities into flux coordinates for magnetohydrodynamic stability calculation is performed by a method which preserves the convergence properties of the cubic Hermite elements. Convergence studies show the behaviour of the stability results when the equilibrium mesh is varied. (author) 13 refs., 3 tabs
Elastoplastic buckling of quasi axisymmetric shells of revolution
International Nuclear Information System (INIS)
Combescure, A.
1987-01-01
This paper gives the formulation of a finite element which allows the computation of quasi axisymmetric shells of revolution. This element has two nodes and the displacement field is developped in Fourier series. In this paper, an emphasis is put on the elastic and plastic buckling formulation. Two examples are developped in details showing the applicability and the interest of such a finite element. (orig.)
Numerical methods for axisymmetric and 3D nonlinear beams
Pinton, Gianmarco F.; Trahey, Gregg E.
2005-04-01
Time domain algorithms that solve the Khokhlov--Zabolotzskaya--Kuznetsov (KZK) equation are described and implemented. This equation represents the propagation of finite amplitude sound beams in a homogenous thermoviscous fluid for axisymmetric and fully three dimensional geometries. In the numerical solution each of the terms is considered separately and the numerical methods are compared with known solutions. First and second order operator splitting are used to combine the separate terms in the KZK equation and their convergence is examined.
Electromagnetic energy harvester for harvesting acoustic energy
Indian Academy of Sciences (India)
Farid U Khan
Acoustics; energy harvesting; electromagnetic; Helmholtz resonator; sound pressure level; suspended coil. ... WSNs, which are supposed to operate for longer period of time. However ... several ambient energies such as wind, thermal, vibration, and solar are ..... textile plants in Northern India with specific reference to noise.
Electromagnetic transitions in the atom
International Nuclear Information System (INIS)
Ulehla, I.; Suk, M.; Trka, Z.
1990-01-01
Methods to achieve excitation of atoms are outlined and conditions necessary for the occurrence of electromagnetic transitions in the atomic shell are given. Radiative transitions between the energy states of the atom include stimulated absorption, spontaneous emission, and stimulated emission. Selection rules applying to the majority of observed transitions are given. The parity concept is explained. It is shown how the electromagnetic field and its interaction with the magnetic moment of the atom lead to a disturbance of the energy states of the atom and the occurrence of various electro-optical and magneto-optical phenomena. The Stark effect and electron spin resonance are described. X-rays and X-ray spectra, the Auger effect and the internal photoeffect are also dealt with. The principle of the laser is explained. (M.D.). 22 figs., 1 tab
Modeling axisymmetric flows dynamics of films, jets, and drops
Middleman, Stanley
1995-01-01
This concise book is intended to fulfill two purposes: to provide an important supplement to classic texts by carrying fluid dynamics students on into the realm of free boundary flows; and to demonstrate the art of mathematical modeling based on knowledge, intuition, and observation. In the authors words, the overall goal is make the complex simple, without losing the essence--the virtue--of the complexity.Modeling Axisymmetric Flows: Dynamics of Films, Jets, and Drops is the first book to cover the topics of axisymmetric laminar flows; free-boundary flows; and dynamics of drops, jets, and films. The text also features comparisons of models to experiments, and it includes a large selection of problems at the end of each chapter.Key Features* Contains problems at the end of each chapter* Compares real-world experimental data to theory* Provides one of the first comprehensive examinations of axisymmetric laminar flows, free-boundary flows, and dynamics of drops, jets, and films* Includes development of basic eq...
Options for axisymmetric operation of MFTF-B
International Nuclear Information System (INIS)
Fenstermacher, M.E.; Devoto, R.S.; Thomassen, K.I.
1986-01-01
The flexibility of MFTF-B for axisymmetric experiments has been investigated. Interhcanging the axicell coils and increasing their separation results in an axisymmetric plug cell with 12:1 and 6:1 inner and outer mirror ratios, respectively. For axisymmetric operation, the sloshing-ion neutral beams, ECRH gyrotrons, and the pumping system would be moved to the axicell. Stabilization by E-rings could be explored in this configuration. With the addition of octopole magnets, off-axis multipole stabilization could also be tested. Operating points for octopole and E-ring-stabilized configurations with properties similar to those of the quadrupole MFTF-B, namely T/sub ic/ = 10 - 15 keV and n/sub c/ approx. = 3 x 10 13 cm -3 , have been obtained. Because of the negligible radial transport of central-cell ions, the required neutral-beam power in the central cell has been dramatically reduced. In addition, because MHD stabilization is achieved by off-axis hot electrons in both cases, much lower barrier beta is possible, which aids in reducing the barrier ECRH power. Total ECRH power in the end cell is projected to be approx. =1 MW. Possible operating points for both octopole and E-ring configurations are described along with the stability considerations involved
Engineering studies for the installation of an axi-symmetric metallic divertor in Tore Supra
International Nuclear Information System (INIS)
Doceul, L.; Portafaix, C.; Bucalossi, J.; Saille, A.; Bertrand, B.; Lipa, M.; Missirlian, M.; Jiolat, G.; Samaille, F.; Soler, B.
2011-01-01
Tore Supra (TS) has been designed to operate using technologies that allow long plasma operation (a few minutes), by means of superconducting magnets and actively-cooled high heat flux plasma facing components (PFCs). Actively cooled tungsten PFC will be used in the baffle area of the first ITER divertor. In order to validate such a technology fully (industrial manufacturing, operation with long plasma duration), the implementation of a tungsten axi-symmetric divertor in the tokamak Tore Supra has been studied . With this second major upgrade, Tore Supra should be able to address the problematic of long plasma discharges with a metallic divertor. The proposed divertor is made up of two stainless steel casings containing a copper coil winding located at the top and bottom area of the vacuum vessel. These casings are firmly maintained by connection beams and protected by PFC. This paper describes the mechanical design of this major component and its integration in TS, the associated electromagnetic and thermomechanical analysis, the manufacturing issues and finally the integration of ITER representative PFCs.
International Nuclear Information System (INIS)
Cremaschini, Claudio; Miller, John C.; Tessarotto, Massimo
2011-01-01
A kinetic treatment is developed for collisionless magnetized plasmas occurring in high-temperature, low-density astrophysical accretion disks, such as are thought to be present in some radiatively inefficient accretion flows onto black holes. Quasi-stationary configurations are investigated, within the framework of a Vlasov-Maxwell description. The plasma is taken to be axisymmetric and subject to the action of slowly time-varying gravitational and electromagnetic fields. The magnetic field is assumed to be characterized by a family of locally nested but open magnetic surfaces. The slow collisionless dynamics of these plasmas is investigated, yielding a reduced gyrokinetic Vlasov equation for the kinetic distribution function. For doing this, an asymptotic quasi-stationary solution is first determined, represented by a generalized bi-Maxwellian distribution expressed in terms of the relevant adiabatic invariants. The existence of the solution is shown to depend on having suitable kinetic constraints and conditions leading to particle trapping phenomena. With this solution, one can treat temperature anisotropy, toroidal and poloidal flow velocities, and finite Larmor-radius effects. An asymptotic expansion for the distribution function permits analytic evaluation of all the relevant fluid fields. Basic theoretical features of the solution and their astrophysical implications are discussed. As an application, the possibility of describing the dynamics of slowly time-varying accretion flows and the self-generation of magnetic field by means of a ''kinetic dynamo effect'' are discussed. Both effects are shown to be related to intrinsically kinetic physical mechanisms.
International Nuclear Information System (INIS)
Hatakeyama, R.; Hershkowitz, N.; Majeski, R.; Wen, Y.J.; Brouchous, D.B.; Proberts, P.; Breun, R.A.; Roberts, D.; Vukovic, M.; Tanaka, T.
1997-01-01
A comparison of phenomenological features of plasmas is made with a special emphasis on radio-frequency induced transport, which are maintained when a set of two closely spaced dual half-turn antennas in a central cell of the Phaedrus-B axisymmetric tandem mirror [J. J. Browning et al., Phys. Fluids B 1, 1692 (1989)] is phased to excite electromagnetic fields in the ion cyclotron range of frequencies (ICRF) with m=-1 (rotating with ions) and m=+1 (rotating with electrons) azimuthal modes. Positive and negative electric currents are measured to flow axially to the end walls in the cases of m=-1 and m=+1 excitations, respectively. These parallel nonambipolar ion and electron fluxes are observed to be accompanied by azimuthal ion flows in the same directions as the antenna-excitation modes m. The phenomena are argued in terms of radial particle fluxes due to a nonambipolar transport mechanism [Hojo and Hatori, J. Phys. Soc. Jpn. 60, 2510 (1991); Hatakeyama et al., J. Phys. Soc. Jpn. 60, 2815 (1991), and Phys. Rev. E 52, 6664 (1995)], which are induced when azimuthally traveling ICRF waves are absorbed in the magnetized plasma column. copyright 1997 American Institute of Physics
International Nuclear Information System (INIS)
Arenhoevel, H.
1977-01-01
The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de
FISIC - a full-wave code to model ion cyclotron resonance heating of tokamak plasmas
International Nuclear Information System (INIS)
Kruecken, T.
1988-08-01
We present a user manual for the FISIC code which solves the integrodifferential wave equation in the finite Larmor radius approximation in fully toroidal geometry to simulate ICRF heating experiments. The code models the electromagnetic wave field as well as antenna coupling and power deposition profiles in axisymmetric plasmas. (orig.)
The study of non-axisymmetric control coil applications in NSTX-U
Park, J.-K.; Menard, J. E.; Kim, K.; Gerhardt, S. P.; Maingi, R.; Bialek, J. M.; Sabbagh, S. A.; Berkery, J. W.; Boozer, A. H.; Canik, J. M.; Evans, T. E.
2013-10-01
As expanded 3D field capability is essential to meet NSTX-U programmatic goals and support ITER, non-axisymmetric control coil (NCC) configurations have been proposed and studied to assess potential physics applications. IPEC-NTV, POCA, and TRIP-3D code analysis show that NCC can provide a range of non-resonant error field control while minimizing resonant error field, and enhance NTV variability to better control rotation and shear, and also largely vary stochastic layers in the edge while maintaining similar plasma response characteristics. VALEN-3D analysis shows that RWM control performance increases with NCC and indicates even the possibility of operation near the ideal-wall limit. In addition, 3D analysis using stellarator codes such as COBRA indicates that NCC can directly broaden ballooning unstable region across radius and thus can be used to improve ELM pacing in NSTX-U. Relevant figures-of-merit are defined and used to quantify these NCC physics capabilities, as will be presented with future analysis plans. This work was supported by DOE Contract DE-AC02-09CH11466.
A superconductive electromagnet for nuclear magnetic resonance
International Nuclear Information System (INIS)
Jelinek, J.; Srnka, A.; Studenik, J.
1989-01-01
The superconductive magnet includes at least three concentric frames mounted onto each other; they can be dismantled, or readjusted by axial or rotary motion. The frames carry the main coils and the inner and outer balancing coils. This arrangement offers a higher number of degrees of freedom for the calculation of the system geometry so as to attain the optimum magnetic field configuration. The design also allows the superconductive magnet to be operated at a liquid helium level depressed below the upper magnet plate. (J.B.). 1 fig
Electromagnetic transition between molecular resonances in Be
Indian Academy of Sciences (India)
2014-11-04
Nov 4, 2014 ... Experimental results are compared with various theories. The outlook on the ... D R Chakrabarty state-of-the-art ab-initio Monte Carlo calculations [4], starting from the basic nucleon– ... tion probability B(E2) for the 4. + to 2. +.
Intermediate energy electromagnetic interactions
International Nuclear Information System (INIS)
Garcon, M.
1994-11-01
Polarization measurements in electromagnetic interactions are reviewed. Deep inelastic scattering of polarized electrons and muons an polarized targets, photoproduction of pseudoscalar mesons on protons, photonuclear reactions, and the electromagnetic structure of the deuteron are discussed. (K.A.)
Intermediate energy electromagnetic interactions
Energy Technology Data Exchange (ETDEWEB)
Garcon, M.
1994-11-01
Polarization measurements in electromagnetic interactions are reviewed. Deep inelastic scattering of polarized electrons and muons an polarized targets, photoproduction of pseudoscalar mesons on protons, photonuclear reactions, and the electromagnetic structure of the deuteron are discussed. (K.A.).
Electromagnetic wave matching device
International Nuclear Information System (INIS)
Hirata, Yosuke; Mitsunaka, Yoshika; Hayashi, Ken-ichi; Ito, Yasuyuki.
1997-01-01
The present invention provides an electromagnetic wave matching capable of reducing a cost for the transmission system in a system of using electromagnetic waves for plasma heating of a thermonuclear reactor. Namely, incident electromagnetic waves are reflected by using a plurality of phase correction mirrors. The reflected electromagnetic waves are connected to an external transmission system through an exit. The phase correction mirrors have such a shape to receive a plurality of beam-like electromagnetic waves and output electromagnetic waves by the number different from the number of the received electromagnetic wave beams having a predetermined distribution. Further, at least two of the phase correction mirrors have such a shape to change the phase of the electromagnetic waves beams incident to the reflection surface of the phase correction mirrors by a predetermined amount corresponding to the position of the reflection surface. Then, the cost for transmission system can greatly be reduced. (I.S.)
Energy Technology Data Exchange (ETDEWEB)
Balakrishna, C; Sarma, B S [Defence Research and Development Laboratory, Hyderabad (India)
1989-02-01
A formulation for axisymmetric shell analysis under asymmetric load based on Fourier series representation and using field consistent 3 noded curved axisymmetric shell element is presented. Different field inconsistent/consistent interpolations for an element based on shear flexible theory have been studied for thick and thin shells under asymmetric loads. Various examples covering axisymmetric as well as asymmetric loading cases have been analyzed and numerical results show a good agreement with the available results in the case of thin shells. 12 refs.
Dielectric Sensors Based on Electromagnetic Energy Tunneling
Siddiqui, Omar; Kashanianfard, Mani; Ramahi, Omar
2015-01-01
We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide. PMID:25835188
Dielectric Sensors Based on Electromagnetic Energy Tunneling
Directory of Open Access Journals (Sweden)
Omar Siddiqui
2015-03-01
Full Text Available We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide.
Electromagnetic Education in India
Bajpai, Shrish; Asif, Siddiqui Sajida; Akhtar, Syed Adnan
2016-01-01
Out of the four fundamental interactions in nature, electromagnetics is one of them along with gravitation, strong interaction and weak interaction. The field of electromagnetics has made much of the modern age possible. Electromagnets are common in day-to-day appliances and are becoming more conventional as the need for technology increases.…
Institute of Scientific and Technical Information of China (English)
李先枢; 徐家进; 高燕球
1990-01-01
Based on the first part of this paper (Science in China, 33(1990), 982—995), further research has been done on quasi-equivalence relation and asymmetrical character of axisymmetrical phase-conjugatlon resonator(PCR). A series of calculations for axisymmetrical PCR(hundreds of transverse modes in 66 axisymmetrical PCRs) have been carried out, and the results are compared with those of corresponding conventional laser resonators. Fundamental properties of the transverse modes (TEMs) in PCR are summarized. This makes possible a rough estimation of the properties of various TEMs in these simple PCR, including different geometrical structures.
International Nuclear Information System (INIS)
Simonen, T.; Cohen, R.; Correll, D.; Fowler, K.; Post, D.; Berk, H.; Horton, W.; Hooper, E.B.; Fisch, N.; Hassam, A.; Baldwin, D.; Pearlstein, D.; Logan, G.; Turner, B.; Moir, R.; Molvik, A.; Ryutov, D.; Ivanov, A.A; Kesner, J.; Cohen, B.; McLean, H.; Tamano, T.; Tang, X.Z.; Imai, T.
2008-01-01
Experimental results, theory and innovative ideas now point with increased confidence to the possibility of a Gas Dynamic Trap (GDT) neutron source which would be on the path to an attractively simple Axisymmetric Tandem Mirror (ATM) power plant. Although magnetic mirror research was terminated in the US 20 years ago, experiments continued in Japan (Gamma 10) and Russia (GDT), with a very small US effort. This research has now yielded data, increased understanding, and generated ideas resulting in the new concepts described here. Early mirror research was carried out with circular axisymmetric magnets. These plasmas were MHD unstable due to the unfavorable magnetic curvature near the mid-plane. Then the minimum-B concept emerged in which the field line curvature was everywhere favorable and the plasma was situated in a MHD stable magnetic well (70% average beta in 2XII-B). The Ioffe-bar or baseball-coil became the standard for over 40 years. In the 1980's, driven by success with minimum-B stabilization and the control of ion cyclotron instabilities in PR6 and 2XII-B, mirrors were viewed as a potentially attractive concept with near-term advantages as a lower Q neutron source for applications such as a hybrid fission fuel factory or toxic waste burner. However there are down sides to the minimum-B geometry: coil construction is complex; restraining magnetic forces limit field strength and mirror ratios. Furthermore, the magnetic field lines have geodesic curvature which introduces resonant and neoclassical radial transport as observed in early tandem mirror experiments. So what now leads us to think that simple axisymmetric mirror plasmas can be stable? The Russian GDT experiment achieves on-axis 60% beta by peaking of the kinetic plasma pressure near the mirror throat (where the curvature is favorable) to counter-balance the average unfavorable mid-plane curvature. Then a modest augmentation of plasma pressure in the expander results in stability. The GDT
Energy Technology Data Exchange (ETDEWEB)
Simonen, T; Cohen, R; Correll, D; Fowler, K; Post, D; Berk, H; Horton, W; Hooper, E B; Fisch, N; Hassam, A; Baldwin, D; Pearlstein, D; Logan, G; Turner, B; Moir, R; Molvik, A; Ryutov, D; Ivanov, A A; Kesner, J; Cohen, B; McLean, H; Tamano, T; Tang, X Z; Imai, T
2008-10-24
Experimental results, theory and innovative ideas now point with increased confidence to the possibility of a Gas Dynamic Trap (GDT) neutron source which would be on the path to an attractively simple Axisymmetric Tandem Mirror (ATM) power plant. Although magnetic mirror research was terminated in the US 20 years ago, experiments continued in Japan (Gamma 10) and Russia (GDT), with a very small US effort. This research has now yielded data, increased understanding, and generated ideas resulting in the new concepts described here. Early mirror research was carried out with circular axisymmetric magnets. These plasmas were MHD unstable due to the unfavorable magnetic curvature near the mid-plane. Then the minimum-B concept emerged in which the field line curvature was everywhere favorable and the plasma was situated in a MHD stable magnetic well (70% average beta in 2XII-B). The Ioffe-bar or baseball-coil became the standard for over 40 years. In the 1980's, driven by success with minimum-B stabilization and the control of ion cyclotron instabilities in PR6 and 2XII-B, mirrors were viewed as a potentially attractive concept with near-term advantages as a lower Q neutron source for applications such as a hybrid fission fuel factory or toxic waste burner. However there are down sides to the minimum-B geometry: coil construction is complex; restraining magnetic forces limit field strength and mirror ratios. Furthermore, the magnetic field lines have geodesic curvature which introduces resonant and neoclassical radial transport as observed in early tandem mirror experiments. So what now leads us to think that simple axisymmetric mirror plasmas can be stable? The Russian GDT experiment achieves on-axis 60% beta by peaking of the kinetic plasma pressure near the mirror throat (where the curvature is favorable) to counter-balance the average unfavorable mid-plane curvature. Then a modest augmentation of plasma pressure in the expander results in stability. The GDT
Electromagnetic compression gun for hypervelocity projectile acceleration
International Nuclear Information System (INIS)
Woo, J.T.
1987-01-01
The rapid acceleration of projectiles to very high velocities has applications in many areas. The general requirements for an effective system is simplicity, reliability, compactness and good efficiency. The authors developed a concept by using electromagnetic forces to compressionally heat a plasma to high temperature and pressure to serve as the propellant for the acceleration of projectiles. The concept shares the simplicity of the light gas gun, but because of the high temperature of the propellant, is capable of significantly higher performance. Unlike the electrothermal gun approach to raise the propellant temperature by resistive heating, the electromagnetic concept is more efficient at higher temperatures. Operationally, the concept resembles a railgun in requiring a large pulsed current to drive the system. However, the current flow in this case is entirely external to the gun barrel and is axisymmetric. Therefore, many of the problems associated with railgun operations are avoided. Furthermore, because the current channel is external, there is also greater flexibility in the choice of load impedance to match to the power supply. The concept can also be generalized to a multi-stage regenerative system driven by a pulse forming network to resemble a coaxial accelerator
Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder
Directory of Open Access Journals (Sweden)
E. S. Nehru
2012-01-01
Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.
Whether diffusion in axisymmetric confinement systems is intrinsically ambipolar
International Nuclear Information System (INIS)
Kovrizhnykh, L.M.
1997-01-01
The problem of diffusion ambipolarity in axisymmetric magnetic systems is analyzed. The question is discussed of whether diffusion is intrinsically ambipolar (and if so, then in which particular cases) or the ambipolarity constraint is an additional independent condition, which does not follow from the equations of motion and, hence, contains new information. It is shown that the second assertion is correct: strictly speaking, diffusion can never be intrinsically ambipolar, and, in the presence of several different mechanisms causing electron and ion losses across the magnetic field, only the total fluxes, but not the partial ones, should satisfy the ambipolarity constraint. (UK)
Fusion-product transport in axisymmetric tokamaks: losses and thermalization
International Nuclear Information System (INIS)
Hively, L.M.
1980-01-01
High-energy fusion-product losses from an axisymmetric tokamak plasma are studied. Prompt-escape loss fluxes (i.e. prior to slowing down) are calculated including the non-separable dependence of flux as a function of poloidal angle and local angle-of-incidence at the first wall. Fusion-product (fp) thermalization and heating are calculated assuming classical slowing down. The present analytical model describes fast ion orbits and their distribution function in realistic, high-β, non-circular tokamak equilibria. First-orbit losses, trapping effects, and slowing-down drifts are also treated
A high-precision algorithm for axisymmetric flow
Directory of Open Access Journals (Sweden)
A. Gokhman
1995-01-01
Full Text Available We present a new algorithm for highly accurate computation of axisymmetric potential flow. The principal feature of the algorithm is the use of orthogonal curvilinear coordinates. These coordinates are used to write down the equations and to specify quadrilateral elements following the boundary. In particular, boundary conditions for the Stokes' stream-function are satisfied exactly. The velocity field is determined by differentiating the stream-function. We avoid the use of quadratures in the evaluation of Galerkin integrals, and instead use splining of the boundaries of elements to take the double integrals of the shape functions in closed form. This is very accurate and not time consuming.
Preserving spherical symmetry in axisymmetric coordinates for diffusion problems
International Nuclear Information System (INIS)
Brunner, T. A.; Kolev, T. V.; Bailey, T. S.; Till, A. T.
2013-01-01
Persevering symmetric solutions, even in the under-converged limit, is important to the robustness of production simulation codes. We explore the symmetry preservation in both a continuous nodal and a mixed finite element method. In their standard formulation, neither method preserves spherical solution symmetry in axisymmetric (RZ) coordinates. We propose two methods, one for each family of finite elements, that recover spherical symmetry for low-order finite elements on linear or curvilinear meshes. This is a first step toward understanding achieving symmetry for higher-order elements. (authors)
SIGMARZ, Stress Analysis of Axisymmetric or Plane Structures
International Nuclear Information System (INIS)
1978-01-01
1 - Nature of the physical problem solved: Classic stress analysis program for axisymmetric or plane geometric structures. 2 - Method of solution: The finite element method is used. Input are the finite element nodes, the imposed displacements, the applied forces at the nodes and the volumetric distributed forces. The linear equation system is solved by the Cholesky method. 3 - Restrictions on the complexity of the problem: Maximum number of nodes: 800; Maximum number of elements: 1300; Maximum number of displacements: 300; Maximum band width: 72
Modelling Acoustic Wave Propagation in Axisymmetric Varying-Radius Waveguides
DEFF Research Database (Denmark)
Bæk, David; Willatzen, Morten
2008-01-01
A computationally fast and accurate model (a set of coupled ordinary differential equations) for fluid sound-wave propagation in infinite axisymmetric waveguides of varying radius is proposed. The model accounts for fluid heat conduction and fluid irrotational viscosity. The model problem is solved...... by expanding solutions in terms of cross-sectional eigenfunctions following Stevenson’s method. A transfer matrix can be easily constructed from simple model responses of a given waveguide and later used in computing the response to any complex wave input. Energy losses due to heat conduction and viscous...
An axisymmetric PFEM formulation for bottle forming simulation
Ryzhakov, Pavel B.
2017-01-01
A numerical model for bottle forming simulation is proposed. It is based upon the Particle Finite Element Method (PFEM) and is developed for the simulation of bottles characterized by rotational symmetry. The PFEM strategy is adapted to suit the problem of interest. Axisymmetric version of the formulation is developed and a modified contact algorithm is applied. This results in a method characterized by excellent computational efficiency and volume conservation characteristics. The model is validated. An example modelling the final blow process is solved. Bottle wall thickness is estimated and the mass conservation of the method is analysed.
Axisymmetric tandem mirror stabilized by a magnetic limiter
International Nuclear Information System (INIS)
Kesner, J.; Post, R.S.; Lane, B.
1985-06-01
In order to stabilize MHD-like, fast growing m = 1 fluctuations in the central cell of a tandem mirror we propose the introduction of a magnetic limiter. The magnetic limiter would create a ring null in the magnetic field. Electrons which enter the null can stream azimuthally and thereby ''short-circuit'' m = 1 fluctuations. Some pressure could be maintained on the separatrix flux surface by locating the null on a local magnetic maxima or by axial plugging. This scheme introduces the possibility of a fully axisymmetric tandem mirror
Flow in axisymmetric expansion in a catalytic converter
DEFF Research Database (Denmark)
Gotfredsen, Erik; Meyer, Knud Erik
The flow in an axisymmetric expansion (circular diffusor) is used in many different engineering applications, such as heat exchangers, catalytic converters and filters. These applications require a relatively uniform flow at the inlet. To minimise the pressure loss, an ideal solution would...... Velocimetry (PIV) is a unique method that resolve the entire cross flow. This type of flow is expected to have a fluctuating ‘jet’-like structure from the smaller inlet pipe into the larger converter. The fluctuations of the jet are difficult, if not impossible, to capture with standard time averaged models...
CSIR Research Space (South Africa)
Shatalov, MY
2010-01-01
Full Text Available artefacts. An elaborate discussion of these artefacts is given by Yenwong-Fai, (Yenwong-Fai, 2008). These artefacts could be simply detected and eliminated from the dispersion plots by program tools.Our algorithm, as it has been implemented, does.... Arthur G. Every and our student Alfred S. Yenwong-Fai participating in the investigation of the non-axisymmetric case of the piezoelectric cylinder vibrations (Shatalov, et al. 2009). I also want to thank Mr. Yuri M. Shatalov who investigated...
Elastic layer under axisymmetric indentation and surface energy effects
Intarit, Pong-in; Senjuntichai, Teerapong; Rungamornrat, Jaroon
2018-04-01
In this paper, a continuum-based approach is adopted to investigate the contact problem of an elastic layer with finite thickness and rigid base subjected to axisymmetric indentation with the consideration of surface energy effects. A complete Gurtin-Murdoch surface elasticity is employed to consider the influence of surface stresses. The indentation problem of a rigid frictionless punch with arbitrary axisymmetric profiles is formulated by employing the displacement Green's functions, derived with the aid of Hankel integral transform technique. The problem is solved by assuming the contact pressure distribution in terms of a linear combination of admissible functions and undetermined coefficients. Those coefficients are then obtained by employing a collocation technique and an efficient numerical quadrature scheme. The accuracy of proposed solution technique is verified by comparing with existing solutions for rigid indentation on an elastic half-space. Selected numerical results for the indenters with flat-ended cylindrical and paraboloidal punch profiles are presented to portray the influence of surface energy effects on elastic fields of the finite layer. It is found that the presence of surface stresses renders the layer stiffer, and the size-dependent behavior of elastic fields is observed in the present solutions. In addition, the surface energy effects become more pronounced with smaller contact area; thus, the influence of surface energy cannot be ignored in the analysis of indentation problem especially when the indenter size is very small such as in the case of nanoindentation.
Aerodynamics characteristic of axisymmetric surface protuberance in supersonic regime
Qamar, Adnan; Sanghi, Sanjeev
2012-01-01
The present work deals with the problem of an axi-symmetric surface protuberance mounted on a spherical nosed body of revolution. The numerical computations are carried out for laminar supersonic viscous flow for trapezoidal shape axi-symmetric protuberances. A free stream Mach number ranging from 3 to 8 in steps of 1 at a fixed free stream Reynolds number of 1.8x10(4) has been used in the present study. The steady solutions are obtained using a time marching approach. A newly developed Particle Velocity Upwinding (PVU) scheme has been used for the computation. The spatial flow pattern exhibits a strong bow shock in front of the hemispherical nose, which engulfs the entire base body. Near the protuberance, the fluid particle decelerates due to the adverse pressure created by the protuberance and thus the flow separates in front of the protuberance. This point of separation is found to be a function of Mach number and the protuberance shape. A low-pressure expansion region dominates the base region of the obstacle. The reattachment point for the base separation is also a function of Mach number. As the Mach number is increased the reattachment point shifts toward the protuberances base. A weak recompression shock is also seen in the base, which affects the separated zone behind the protuberance. The important design parameters such as skin friction, heat transfer, drag, and surface pressure coefficients are reported extensively.
Application of the Least Squares Method in Axisymmetric Biharmonic Problems
Directory of Open Access Journals (Sweden)
Vasyl Chekurin
2016-01-01
Full Text Available An approach for solving of the axisymmetric biharmonic boundary value problems for semi-infinite cylindrical domain was developed in the paper. On the lateral surface of the domain homogeneous Neumann boundary conditions are prescribed. On the remaining part of the domain’s boundary four different biharmonic boundary pieces of data are considered. To solve the formulated biharmonic problems the method of least squares on the boundary combined with the method of homogeneous solutions was used. That enabled reducing the problems to infinite systems of linear algebraic equations which can be solved with the use of reduction method. Convergence of the solution obtained with developed approach was studied numerically on some characteristic examples. The developed approach can be used particularly to solve axisymmetric elasticity problems for cylindrical bodies, the heights of which are equal to or exceed their diameters, when on their lateral surface normal and tangential tractions are prescribed and on the cylinder’s end faces various types of boundary conditions in stresses in displacements or mixed ones are given.
Stress analysis in a non axisymmetric loaded reactor pressure vessel
International Nuclear Information System (INIS)
Albuquerque, Levi Barcelos; Assis, Gracia Menezes V. de; Miranda, Carlos Alexandre J.; Cruz, Julio Ricardo B.; Mattar Neto, Miguel
1995-01-01
In this work we intend to present the stress analysis of a PWR vessel under postulated concentrated loads. The vessel was modeled with Axisymmetric solid 4 nodes harmonic finite elements with the use of the ANSYS program, version 5.0. The bolts connecting the vessel flanges were modeled with beam elements. Some considerations were made to model the contact between the flanges. The perforated part of the vessel tori spherical head was modeled (with reduced properties due to its holes) to introduce its stiffness and loads but was not within the scope of this work. The loading consists of some usual ones, as pressure, dead weight, bolts preload, seismic load and some postulated ones as concentrated loads, over the vessel, modeled by Fourier Series. The results in the axisymmetric model are taken in terms of linearized stresses, obtained in some circumferential positions and for each position, in some sections along the vessel. Using the ASME Code (Section III, Division 1, Sub-section NB) the stresses are within the allowable limits. In order to draw some conclusions about stress linearization, the membrane plus bending stresses (Pl + Pb) are obtained and compared in some sections, using three different methods. (author)
Hot Wire Measurements in a Axisymmetric Shear Layer with Swirl
Ewing, D.; Pollard, A.
1996-11-01
It is well known that the introduction of swirl in an axisymmetric jet can influence the development of and mixing in the near field of the jet. Recent efforts to compute this flow have demonstrated that the development of the near field is dependent on parameters at the jet outlet other than distribution of the swirl component, such as the distribution the mean radial velocity (Xai, J.L., Smith, B.L., Benim, A. C., Schmidli, J., and Yadigaroglu, G. (1996) Influence of Boundary Conditions on Swirling Flow in Combustors, Proc. ASME Fluid. Eng. Div. Summer Meeting), San Diego, Ca., July 7-11.. An experimental rig has been designed to produce co-axial round and annular swirling jets with uniform outlet conditions in each flow. The flow rate and swirl component from each of these jets can be controlled independently and the rig can be configured to produce both co- and counter-swirling flows. Thus, the rig can be used to carry out an extensive investigation of the effect of swirl on the development of axisymmetric flows. The key design features of the rig and the first sets of hot-wire measurements in the shear layer will be reported here.
SEAWAT-based simulation of axisymmetric heat transport.
Vandenbohede, Alexander; Louwyck, Andy; Vlamynck, Nele
2014-01-01
Simulation of heat transport has its applications in geothermal exploitation of aquifers and the analysis of temperature dependent chemical reactions. Under homogeneous conditions and in the absence of a regional hydraulic gradient, groundwater flow and heat transport from or to a well exhibit radial symmetry, and governing equations are reduced by one dimension (1D) which increases computational efficiency importantly. Solute transport codes can simulate heat transport and input parameters may be modified such that the Cartesian geometry can handle radial flow. In this article, SEAWAT is evaluated as simulator for heat transport under radial flow conditions. The 1971, 1D analytical solution of Gelhar and Collins is used to compare axisymmetric transport with retardation (i.e., as a result of thermal equilibrium between fluid and solid) and a large diffusion (conduction). It is shown that an axisymmetric simulation compares well with a fully three dimensional (3D) simulation of an aquifer thermal energy storage systems. The influence of grid discretization, solver parameters, and advection solution is illustrated. Because of the high diffusion to simulate conduction, convergence criterion for heat transport must be set much smaller (10(-10) ) than for solute transport (10(-6) ). Grid discretization should be considered carefully, in particular the subdivision of the screen interval. On the other hand, different methods to calculate the pumping or injection rate distribution over different nodes of a multilayer well lead to small differences only. © 2013, National Ground Water Association.
Axisymmetric magnetic mirrors for plasma confinement. Recent development and perspectives
International Nuclear Information System (INIS)
Kruglyakov, E.P.; Dimov, G.I.; Ivanov, A.A.; Koidan, V.S.
2003-01-01
Mirrors are the only one class of fusion systems which completely differs topologically from the systems with closed magnetic configurations. At present, three modern types of different mirror machines for plasma confinement and heating exist in Novosibirsk (Gas Dynamic Trap,- GDT, Multi-mirror,- GOL-3, and Tandem Mirror,- AMBAL-M). All these systems are attractive from the engineering point of view because of very simple axisymmetric geometry of magnetic configurations. In the present paper, the status of different confinement systems is presented. The experiments most crucial for the mirror concept are described such as a demonstration of different principles of suppression of electron heat conductivity (GDT, GOL-3), finding of MHD stable regimes of plasma confinement in axisymmetric geometry of magnetic field (GDT, AMBAL-M), an effective heating of a dense plasma by relativistic electron beam (GOL-3), observation of radial diffusion of quiescent plasma with practically classical diffusion coefficient (AMBAL-M), etc. It should be mentioned that on the basis of the GDT it is possible to make a very important intermediate step. Using 'warm' plasma and oblique injection of fast atoms of D and T one can create a powerful 14 MeV neutron source with a moderate irradiation area (about 1 square meter) and, accordingly, with low tritium consumption. The main plasma parameters achieved are presented and the future perspectives of different mirror machines are outlined. (author)
Scattering of ultrashort electromagnetic pulses on metal clusters
International Nuclear Information System (INIS)
Astapenko, V. A.; Sakhno, S. V.
2016-01-01
We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.
Scattering of ultrashort electromagnetic pulses on metal clusters
Energy Technology Data Exchange (ETDEWEB)
Astapenko, V. A., E-mail: astval@mail.ru; Sakhno, S. V. [Moscow Institute of Physics and Technology (State University) (Russian Federation)
2016-12-15
We have calculated and analyzed the probability of ultrashort electromagnetic pulse (USP) scattering on small metal clusters in the frequency range of plasmon resonances during the field action. The main attention is devoted to dependence of the probability of scattering on the pulse duration for various detunings of the USP carrier frequency from the plasmon resonance frequency. Peculiarities of the USP scattering from plasmon resonances with various figures of merit are revealed.
Topological Fluid Mechanics with Applications to Free Surfaces and Axisymmetric Flows
DEFF Research Database (Denmark)
Brøns, Morten
1996-01-01
Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow.......Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow....
International Nuclear Information System (INIS)
Strait, E. J.; Park, J. K.; Marmar, E. S.; Ahn, J. W.; Berkery, J. W.; Burrell, K. H.; Canik, J. M.; Delgado-Aparicio, L.; Ferraro, N. M.; Garofalo, A. M.; Gates, D. A.; Greenwald, M.; Kim, K.; King, J. D.; Lanctot, M. J.; Lazerson, S. A.; Liu, Y. Q.; Lore, J. D.; Menard, J. E.; Nazikian, R.; Shafer, M. W.; Paz-Soldan, C.; Reiman, A. H.; Rice, J. E.; Sabbagh, S. A.; Sugiyama, L.; Turnbull, A. D.; Volpe, F.; Wang, Z. R.; Wolfe, S. M.
2014-01-01
The goal of the 2014 Joint Research Target (JRT) has been to conduct experiments and analysis to investigate and quantify the response of tokamak plasmas to non-axisymmetric (3D) magnetic fields. Although tokamaks are conceptually axisymmetric devices, small asymmetries often result from inaccuracies in the manufacture and assembly of the magnet coils, or from nearby magnetized objects. In addition, non-axisymmetric fields may be deliberately applied for various purposes. Even at small amplitudes of order 10 -4 of the main axisymmetric field, such ''3D'' fields can have profound impacts on the plasma performance. The effects are often detrimental (reduction of stabilizing plasma rotation, degradation of energy confinement, localized heat flux to the divertor, or excitation of instabilities) but may in some case be beneficial (maintenance of rotation, or suppression of instabilities). In general, the magnetic response of the plasma alters the 3D field, so that the magnetic field configuration within the plasma is not simply the sum of the external 3D field and the original axisymmetric field. Typically the plasma response consists of a mixture of local screening of the external field by currents induced at resonant surfaces in the plasma, and amplification of the external field by stable kink modes. Thus, validated magnetohydrodynamic (MHD) models of the plasma response to 3D fields are crucial to the interpretation of existing experiments and the prediction of plasma performance in future devices. The non-axisymmetric coil sets available at each facility allow well-controlled studies of the response to external 3D fields. The work performed in support of the 2014 Joint Research Target has included joint modeling and analysis of existing experimental data, and collaboration on new experiments designed to address the goals of the JRT. A major focus of the work was validation of numerical models through quantitative comparison to experimental data
Energy Technology Data Exchange (ETDEWEB)
Strait, E. J. [General Atomics, San Diego, CA (United States); Park, J. -K. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Marmar, E. S. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ahn, J. -W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Berkery, J. W. [Columbia Univ., New York, NY (United States); Burrell, K. H. [General Atomics, San Diego, CA (United States); Canik, J. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delgado-Aparicio, L. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Ferraro, N. M. [General Atomics, San Diego, CA (United States); Garofalo, A. M. [General Atomics, San Diego, CA (United States); Gates, D. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Greenwald, M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Kim, K. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); King, J. D. [General Atomics, San Diego, CA (United States); Lanctot, M. J. [General Atomics, San Diego, CA (United States); Lazerson, S. A. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Liu, Y. Q. [Culham Science Centre, Abingdon (United Kingdom). Euratom/CCFE Association; Logan, N. C. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Lore, J. D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Menard, J. E. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Nazikian, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Shafer, M. W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Paz-Soldan, C. [General Atomics, San Diego, CA (United States); Reiman, A. H. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Rice, J. E. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Sabbagh, S. A. [Columbia Univ., New York, NY (United States); Sugiyama, L. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Turnbull, A. D. [General Atomics, San Diego, CA (United States); Volpe, F. [Columbia Univ., New York, NY (United States); Wang, Z. R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Wolfe, S. M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2014-09-30
The goal of the 2014 Joint Research Target (JRT) has been to conduct experiments and analysis to investigate and quantify the response of tokamak plasmas to non-axisymmetric (3D) magnetic fields. Although tokamaks are conceptually axisymmetric devices, small asymmetries often result from inaccuracies in the manufacture and assembly of the magnet coils, or from nearby magnetized objects. In addition, non-axisymmetric fields may be deliberately applied for various purposes. Even at small amplitudes of order 10^{-4} of the main axisymmetric field, such “3D” fields can have profound impacts on the plasma performance. The effects are often detrimental (reduction of stabilizing plasma rotation, degradation of energy confinement, localized heat flux to the divertor, or excitation of instabilities) but may in some case be beneficial (maintenance of rotation, or suppression of instabilities). In general, the magnetic response of the plasma alters the 3D field, so that the magnetic field configuration within the plasma is not simply the sum of the external 3D field and the original axisymmetric field. Typically the plasma response consists of a mixture of local screening of the external field by currents induced at resonant surfaces in the plasma, and amplification of the external field by stable kink modes. Thus, validated magnetohydrodynamic (MHD) models of the plasma response to 3D fields are crucial to the interpretation of existing experiments and the prediction of plasma performance in future devices. The non-axisymmetric coil sets available at each facility allow well-controlled studies of the response to external 3D fields. The work performed in support of the 2014 Joint Research Target has included joint modeling and analysis of existing experimental data, and collaboration on new experiments designed to address the goals of the JRT. A major focus of the work was validation of numerical models through quantitative comparison to experimental data, in
Development of axisymmetric lattice Boltzmann flux solver for complex multiphase flows
Wang, Yan; Shu, Chang; Yang, Li-Ming; Yuan, Hai-Zhuan
2018-05-01
This paper presents an axisymmetric lattice Boltzmann flux solver (LBFS) for simulating axisymmetric multiphase flows. In the solver, the two-dimensional (2D) multiphase LBFS is applied to reconstruct macroscopic fluxes excluding axisymmetric effects. Source terms accounting for axisymmetric effects are introduced directly into the governing equations. As compared to conventional axisymmetric multiphase lattice Boltzmann (LB) method, the present solver has the kinetic feature for flux evaluation and avoids complex derivations of external forcing terms. In addition, the present solver also saves considerable computational efforts in comparison with three-dimensional (3D) computations. The capability of the proposed solver in simulating complex multiphase flows is demonstrated by studying single bubble rising in a circular tube. The obtained results compare well with the published data.
Classical mechanics and electromagnetism in accelerator physics
Stupakov, Gennady
2018-01-01
This self-contained textbook with exercises discusses a broad range of selected topics from classical mechanics and electromagnetic theory that inform key issues related to modern accelerators. Part I presents fundamentals of the Lagrangian and Hamiltonian formalism for mechanical systems, canonical transformations, action-angle variables, and then linear and nonlinear oscillators. The Hamiltonian for a circular accelerator is used to evaluate the equations of motion, the action, and betatron oscillations in an accelerator. From this base, we explore the impact of field errors and nonlinear resonances. This part ends with the concept of the distribution function and an introduction to the kinetic equation to describe large ensembles of charged particles and to supplement the previous single-particle analysis of beam dynamics. Part II focuses on classical electromagnetism and begins with an analysis of the electromagnetic field from relativistic beams, both in vacuum and in a resistive pipe. Plane electromagne...
Electromagnetic wave matching device
International Nuclear Information System (INIS)
Hirata, Yosuke; Mitsunaka, Yoshika; Hayashi, Ken-ichi; Ito, Yasuyuki.
1997-01-01
The present invention provides a matching device capable of increasing an efficiency of combining beams of electromagnetic waves outputted from an output window of a gyrotron which is expected for plasma heating of a thermonuclear reactor and an electromagnetic wave transmission system as high as possible. Namely, an electromagnetic wave matching device reflects beams of electromagnetic waves incident from an inlet by a plurality of phase correction mirrors and combines them to an external transmission system through an exit. In this case, the phase correction mirrors change the phase of the beams of electromagnetic waves incident to the phase correction mirrors by a predetermined amount corresponding to the position of the reflection mirrors. Then, the beams of electromagnetic waves outputted, for example, from a gyrotron can properly be shaped as desired for the intensity and the phase. As a result, combination efficiency with the transmission system can be increased. (I.S.)
Electromagnetic Gowdy universe
International Nuclear Information System (INIS)
Charach, C.
1979-01-01
Following Gowdy and Berger we construct an inhomogeneous closed electromagnetic universe with three-torus topology. This model is obtained as a result of the homogeneity breaking in the electromagnetic Bianchi type-I universe and contains interacting gravitational and electromagnetic waves. This cosmological solution provides an exactly solvable model for the study of the nonlinear fully relativistic regime of coupled electromagnetic and gravitational fields in the early universe. The asymptotic behavior is considered (i) in the vicinity of the initial singularity and (ii) in the high-frequency limit. It is shown that the effects of coupling between electromagnetic and gravitational waves cause an evolution which is significantly different from that of the vacuum model. The influence of the primordial homogeneous electromagnetic field on the dynamics of the model is also discussed
Electromagnetic ultrasonic guided waves
Huang, Songling; Li, Weibin; Wang, Qing
2016-01-01
This book introduces the fundamental theory of electromagnetic ultrasonic guided waves, together with its applications. It includes the dispersion characteristics and matching theory of guided waves; the mechanism of production and theoretical model of electromagnetic ultrasonic guided waves; the effect mechanism between guided waves and defects; the simulation method for the entire process of electromagnetic ultrasonic guided wave propagation; electromagnetic ultrasonic thickness measurement; pipeline axial guided wave defect detection; and electromagnetic ultrasonic guided wave detection of gas pipeline cracks. This theory and findings on applications draw on the author’s intensive research over the past eight years. The book can be used for nondestructive testing technology and as an engineering reference work. The specific implementation of the electromagnetic ultrasonic guided wave system presented here will also be of value for other nondestructive test developers.
Basic Electromagnetism and Materials
Moliton, André
2007-01-01
Basic Electromagnetism and Materials is the product of many years of teaching basic and applied electromagnetism. This textbook can be used to teach electromagnetism to a wide range of undergraduate science majors in physics, electrical engineering or materials science. However, by making lesser demands on mathematical knowledge than competing texts, and by emphasizing electromagnetic properties of materials and their applications, this textbook is uniquely suited to students of materials science. Many competing texts focus on the study of propagation waves either in the microwave or optical domain, whereas Basic Electromagnetism and Materials covers the entire electromagnetic domain and the physical response of materials to these waves. Professor André Moliton is Director of the Unité de Microélectronique, Optoélectronique et Polymères (Université de Limoges, France), which brings together three groups studying the optoelectronics of molecular and polymer layers, micro-optoelectronic systems for teleco...
Review on Computational Electromagnetics
Directory of Open Access Journals (Sweden)
P. Sumithra
2017-03-01
Full Text Available Computational electromagnetics (CEM is applied to model the interaction of electromagnetic fields with the objects like antenna, waveguides, aircraft and their environment using Maxwell equations. In this paper the strength and weakness of various computational electromagnetic techniques are discussed. Performance of various techniques in terms accuracy, memory and computational time for application specific tasks such as modeling RCS (Radar cross section, space applications, thin wires, antenna arrays are presented in this paper.
Static electromagnetic frequency changers
Rozhanskii, L L
1963-01-01
Static Electromagnetic Frequency Changers is about the theory, design, construction, and applications of static electromagnetic frequency changers, devices that used for multiplication or division of alternating current frequency. It is originally published in the Russian language. This book is organized into five chapters. The first three chapters introduce the readers to the principles of operation, the construction, and the potential applications of static electromagnetic frequency changers and to the principles of their design. The two concluding chapters use some hitherto unpublished work
Analysis and correction of intrinsic non-axisymmetric magnetic fields in high-β DIII-D plasmas
International Nuclear Information System (INIS)
Garofalo, A.M.; La Haye, R.J.; Scoville, J.T.
2002-01-01
Rapid plasma toroidal rotation, sufficient for stabilization of the n=1 resistive wall mode, can be sustained by improving the axisymmetry of the toroidal magnetic field geometry of DIII-D. The required symmetrization is determined experimentally both by optimizing currents in external n=1 correction coils with respect to the plasma rotation, and by use of the n=1 magnetic feedback to detect and minimize the plasma response to non-axisymmetric fields as β increases. Both methods point to an intrinsic ∼7 G (0.03% of the toroidal field), m/n=2/1 resonant helical field at the q=2 surface as the cause of the plasma rotation slowdown above the no-wall β limit. The drag exerted by this field on the plasma rotation is consistent with the behaviour of 'slipping' in a simple induction motor model. (author)
International Nuclear Information System (INIS)
Gutierrez T, C.; Beltran P, M.
2004-01-01
The neoclassical theory of transport is used to calculate the current efficiency of electronic cyclotron impulsion (ECCD) in an axisymmetric tokamak in the few collisions regime. The standard parameter of the tokamak is used to obtain a system of equations that describe the hydrodynamic of the plasma, where the ponderomotive force (PM) due to high power radio frequency waves is taken in account. The PM force is produced in the proximity of electron cyclotron resonance surface in a specific poloidal localization. The efficiency ECCD is analyzed in the cases of first and second harmonic (for different angles of injection of radio frequency waves) and it is validated using the experimental values of the TCV and T-10 tokamaks. The results are according to those obtained by means of the techniques of the Green functions. (Author)
Model for Electromagnetic Information Leakage
Mao Jian; Li Yongmei; Zhang Jiemin; Liu Jinming
2013-01-01
Electromagnetic leakage will happen in working information equipments; it could lead to information leakage. In order to discover the nature of information in electromagnetic leakage, this paper combined electromagnetic theory with information theory as an innovative research method. It outlines a systematic model of electromagnetic information leakage, which theoretically describes the process of information leakage, intercept and reproduction based on electromagnetic radiation, and ana...
Electromagnetic Interface Testing Facility
Federal Laboratory Consortium — The Electromagnetic Interface Testing facilitysupports such testing asEmissions, Field Strength, Mode Stirring, EMP Pulser, 4 Probe Monitoring/Leveling System, and...
Electromagnetic signatures of far-field gravitational radiation in the 1 + 3 approach
International Nuclear Information System (INIS)
Chua, Alvin J K; Cañizares, Priscilla; Gair, Jonathan R
2015-01-01
Gravitational waves (GWs) from astrophysical sources can interact with background electromagnetic fields, giving rise to distinctive and potentially detectable electromagnetic signatures. In this paper, we study such interactions for far-field gravitational radiation using the 1 + 3 approach to relativity. Linearized equations for the electromagnetic field on perturbed Minkowski space are derived and solved analytically. The inverse Gertsenshteĭn conversion of GWs in a static electromagnetic field is rederived, and the resultant electromagnetic radiation is shown to be significant for highly magnetized pulsars in compact binary systems. We also obtain a variety of nonlinear interference effects for interacting gravitational and electromagnetic waves, although wave–wave resonances previously described in the literature are absent when the electric–magnetic self-interaction is taken into account. The fluctuation and amplification of electromagnetic energy flux as the GW strength increases towards the gravitational–electromagnetic frequency ratio is a possible signature of gravitational radiation from extended astrophysical sources. (paper)
Particle collector scoops for improved exhaust in ''axisymmetric'' devices
International Nuclear Information System (INIS)
Conn, R.W.; Wolf, G.H.
1987-11-01
Application of particle collector scoops in front of the pumping ducts of axisymmetric divertor/magnetic limiter configurations is proposed. These scoops should enclose a significant fraction of the recycling particles. The resulting increase in natural particle pressure in front of the pumping ducts leads to an improved exhaust efficiency. This can permit an extension of the operational margin for density control. Alternatively, aiming at a prescribed exhaust flow in reactor-type devices such as INTOR, the pumping ducts could be reduced in aperture, leaving valuable space for other components. The lay-out of the proposed scheme depends on the heat load on the leading edge in front of the scoop and on the deflector in front of the pumping ducts. 14 refs., 5 figs
Calculation of transport coefficients in an axisymmetric plasma
International Nuclear Information System (INIS)
Shumaker, D.E.
1977-01-01
A method of calculating the transport coefficient in an axisymmetric toroidal plasma is presented. This method is useful in calculating the transport coefficients in a Tokamak plasma confinement device. The particle density and temperature are shown to be a constant on a magnetic flux surface. Transport equations are given for the total particle flux and total energy flux crossing a closed toroidal surface. Also transport equations are given for the toroidal magnetic flux. A computer code was written to calculate the transport coefficients for a three species plasma, electrons and two species of ions. This is useful for calculating the transport coefficients of a plasma which contains impurities. It was found that the particle and energy transport coefficients are increased by a large amount, and the transport coefficients for the toroidal magnetic field are reduced by a small amount
Pressure drop coefficient of laminar Newtonian flow in axisymmetric diffusers
International Nuclear Information System (INIS)
Rosa, S.; Pinho, F.T.
2006-01-01
The laminar flow of Newtonian fluids in axisymmetric diffusers has been numerically investigated to evaluate the pressure-loss coefficient as a function of Reynolds number, diffusion angle and expansion ratio. The numerical simulations were carried out with a finite-volume based code using non-orthogonal collocated grids and second order accurate differencing schemes to discretize all terms of the transport equations. The calculations were carried out for Reynolds numbers between 2 and 200, diffusion angles from 0 deg. to 90 deg. and expansion ratios of 1.5 and 2 and the data are presented in tabular form and as correlations. A simplified 1D theoretical analysis helped explain the various contributions to the loss coefficient and its difference relative to the reversible pressure variation due to differences between the actual and fully developed friction losses, distortions of the velocity profiles and pressure non-uniformity upstream and downstream of the expansion section
Pressure drop coefficient of laminar Newtonian flow in axisymmetric diffusers
Energy Technology Data Exchange (ETDEWEB)
Rosa, S. [Escola Superior de Tecnologia e Gestao, Instituto Politecnico, Campus de Santa Apolonia, 5301-857 Braganca (Portugal)]. E-mail: srosa@ipb.pt; Pinho, F.T. [Centro de Estudos de Fenomenos de Transporte, DEM, Universidade do Minho, Campus de Azurem, 4800-058 Guimaraes (Portugal)]. E-mail: fpinho@fe.up.pt
2006-04-15
The laminar flow of Newtonian fluids in axisymmetric diffusers has been numerically investigated to evaluate the pressure-loss coefficient as a function of Reynolds number, diffusion angle and expansion ratio. The numerical simulations were carried out with a finite-volume based code using non-orthogonal collocated grids and second order accurate differencing schemes to discretize all terms of the transport equations. The calculations were carried out for Reynolds numbers between 2 and 200, diffusion angles from 0 deg. to 90 deg. and expansion ratios of 1.5 and 2 and the data are presented in tabular form and as correlations. A simplified 1D theoretical analysis helped explain the various contributions to the loss coefficient and its difference relative to the reversible pressure variation due to differences between the actual and fully developed friction losses, distortions of the velocity profiles and pressure non-uniformity upstream and downstream of the expansion section.
Development of Compact Quasi-Axisymmetric Stellarator Reactor Configurations
International Nuclear Information System (INIS)
Ku, L.P.; Zarnstorff, M.; White, R.B.; Cooper, W.A.; Sanchez, R.; Neilson, H.; Schmidt, J.A.
2003-01-01
We have started to examine the reactor potential of quasi-axisymmetric (QA) stellarators with an integrated approach that includes systems evaluation, engineering considerations, and plasma and coil optimizations. In this paper, we summarize the progress made so far in developing QA configurations with reduced alpha losses while retaining good MHD stability properties. The minimization of alpha losses is achieved by directly targeting the collisionless orbits to prolong the average resident times. Configurations with an overall energy loss rate of ∼10% or less, including collisional contributions, have been found. To allow remotely maintaining coils and machine components in a reactor environment, there is a desire to simplify to the extent possible the coil design. To this end, finding a configuration that is optimized not only for the alpha confinement and MHD stability but also for the good coil and reactor performance, remains to be a challenging task
Cellular blebs: pressure-driven, axisymmetric, membrane protrusions
Woolley, Thomas E.
2013-07-16
Blebs are cellular protrusions that are used by cells for multiple purposes including locomotion. A mechanical model for the problem of pressure-driven blebs based on force and moment balances of an axisymmetric shell model is proposed. The formation of a bleb is initiated by weakening the shell over a small region, and the deformation of the cellular membrane from the cortex is obtained during inflation. However, simply weakening the shell leads to an area increase of more than 4 %, which is physically unrealistic. Thus, the model is extended to include a reconfiguration process that allows large blebs to form with small increases in area. It is observed that both geometric and biomechanical constraints are important in this process. In particular, it is shown that although blebs are driven by a pressure difference across the cellular membrane, it is not the limiting factor in determining bleb size. © 2013 Springer-Verlag Berlin Heidelberg.
Stability of axisymmetric plasmas in closed line magnetic fields
International Nuclear Information System (INIS)
Simakov, A.N.; Vernon Wong, H.; Berk, H.L.
2003-01-01
The stability of axisymmetric plasmas confined by closed poloidal magnetic field lines is considered. The results are relevant to plasmas in the dipolar fields of stars and planets, as well as the Levitated Dipole Experiment, multipoles, Z pinches and field reversed configurations. The ideal MHD energy principle is employed to study the stability of pressure driven shear Alfven modes. A point dipole is considered in detail to demonstrate that equilibria exist which are MHD stable for arbitrary beta. Effects of sound waves and plasma resistivity are investigated for Z pinch and point dipole equilibria by means of resistive MHD theory. Kinetic theory is used to study drift frequency modes and their interaction with MHD modes near the ideal stability boundary for different collisionality regimes. Effects of collisional dissipation on drift mode stability are explicitly evaluated and applied to a Z pinch. The role of finite Larmor radius effects and drift reversed particles in modifying ideal stability thresholds is examined. (author)
Theory of plasma confinement in non-axisymmetric magnetic fields.
Helander, Per
2014-08-01
The theory of plasma confinement by non-axisymmetric magnetic fields is reviewed. Such fields are used to confine fusion plasmas in stellarators, where in contrast to tokamaks and reversed-field pinches the magnetic field generally does not possess any continuous symmetry. The discussion is focussed on magnetohydrodynamic equilibrium conditions, collisionless particle orbits, and the kinetic theory of equilbrium and transport. Each of these topics is fundamentally affected by the absence of symmetry in the magnetic field: the field lines need not trace out nested flux surfaces, the particle orbits may not be confined, and the cross-field transport can be very large. Nevertheless, by tailoring the magnetic field appropriately, well-behaved equilibria with good confinement can be constructed, potentially offering an attractive route to magnetic fusion. In this article, the mathematical apparatus to describe stellarator plasmas is developed from first principles and basic elements underlying confinement optimization are introduced.
Modeling and simulation of axisymmetric coating growth on nanofibers
International Nuclear Information System (INIS)
Moore, K.; Clemons, C. B.; Kreider, K. L.; Young, G. W.
2007-01-01
This work is a modeling and simulation extension of an integrated experimental/modeling investigation of a procedure to coat nanofibers and core-clad nanostructures with thin film materials using plasma enhanced physical vapor deposition. In the experimental effort, electrospun polymer nanofibers are coated with metallic materials under different operating conditions to observe changes in the coating morphology. The modeling effort focuses on linking simple models at the reactor level, nanofiber level, and atomic level to form a comprehensive model. The comprehensive model leads to the definition of an evolution equation for the coating free surface. This equation was previously derived and solved under a single-valued assumption in a polar geometry to determine the coating morphology as a function of operating conditions. The present work considers the axisymmetric geometry and solves the evolution equation without the single-valued assumption and under less restrictive assumptions on the concentration field than the previous work
Axisymmetric Tornado Simulations with a Semi-Slip Boundary
Directory of Open Access Journals (Sweden)
Brian H. Fiedler
2017-12-01
Full Text Available The structure of natural tornadoes and simulated analogs are sensitive to the lower boundary condition for friction. Three-dimensional numerical simulations of storms require a choice for turbulence parameterizations and resolution of wind near the lower boundary. This article explores some of the consequences of choices of a surface drag coefficient on the structure of a mature simulated tornado, using a conventional axisymmetric model. The surface drag parameterization is explored over the range of the semi-slip condition, including the extremes of no-slip and free-slip. A moderate semi-slip condition allows for an extreme pressure deficit, but without the unrealistic vortex breakdown of the no-slip condition.
Controlled Wake of a Moving Axisymmetric Bluff Body
Lee, E.; Vukasinovic, B.; Glezer, A.
2017-11-01
The aerodynamic loads exerted on a wire-mounted axisymmetric bluff body in prescribed rigid motion are controlled by fluidic manipulation of its near wake. The body is supported by a six-degree of freedom eight-wire traverse and its motion is controlled using a dedicated servo actuator and inline load cell for each wire. The instantaneous aerodynamic forces and moments on the moving body are manipulated by controlled interactions of an azimuthal array of integrated synthetic jet actuators with the cross flow to induce localized flow attachment over the body's aft end and thereby alter the symmetry of the wake. The coupled interactions between the wake structure and the effected aerodynamic loads during prescribed time-periodic and transitory (gust like) motions are investigated with emphasis on enhancing or diminishing the loads for maneuver control, and decoupling the body's motion from its far wake.
Ideal, steady-state, axisymmetric magnetohydrodynamic equations with flow
International Nuclear Information System (INIS)
Baransky, Y.A.
1987-01-01
The motivation of this study is to gain additional understanding of the effect of rotation on the equilibrium of a plasma. The axisymmetric equilibria of ideal magnetohydrodynamics (MHD) with flow have been studied numerically and analytically. A general discussion is provided of previous work on plasmas with flow and comparisons are made to the static model. A variational principle has been derived for the two dimensional problem with comments as to appropriate boundary conditions. An inverse aspect ratio expansion has been used for a study of the toroidal flow equation for both low- and high-β. The inverse aspect ratio expansion has also been used for a study of equations with both poloidal and toroidal flow. An overview is provided of the adaptive finite-difference code which was developed to solve the full equations. (FI)
Numerical study of the axisymmetric ideal MHD stability of Extrap
International Nuclear Information System (INIS)
Benda, M.
1993-04-01
A numerical study of the free-boundary axisymmetric (n=0) ideal magnetohydrodynamical (MHD) motions of the Extrap device is presented. The dependence of stability on current profiles in the plasma and currents in the external conductors is investigated. Results are shown for linear growth-rates and nonlinear saturation amplitudes and their dependence on plasma radius as well as on the conducting shell radius. A method combined of two different algorithms has been developed and tested. The interior region of the plasma is simulated by means of a Lagrangian Finite Element Method (FEM) for ideal magnetohydrodynamics, The method is based on a nonlinear radiation principle for the Lagrangian description of ideal MHD. The Boundary Element Method (BEM) is used together with the Lagrangian FEM to simulate nonlinear motion of an ideal MHD plasma behaviour in a vacuum region under the influence of external magnetic fields. 31 refs
Numerical calculation of axisymmetric non-neutral plasma equilibria
International Nuclear Information System (INIS)
Spencer, R.L.; Rasband, S.N.; Vanfleet, R.R.
1993-01-01
Efficient techniques for computing axisymmetric non-neutral plasma equilibria are described. These equilibria may be obtained either by requiring global thermal equilibrium, by specifying the midplane radial density profile, or by specifying the radial profile of ∫n dz. Both splines and finite-differences are used, and the accuracy of the two is compared by using a new characterization of the thermal equilibrium density profile which gives a simple formula for estimating the radial and axial gradient scale lengths of thermal equilibria. It is found that for global thermal equilibrium 1% accuracy is achieved with splines if the distance between neighboring splines is about two Debye lengths while finite differences require a grid spacing of about one-half Debye length to achieve the same accuracy
Axial turbomachine modelling with a 1D axisymmetric approach
International Nuclear Information System (INIS)
Tauveron, Nicolas; Saez, Manuel; Ferrand, Pascal; Leboeuf, Francis
2007-01-01
This work concerns the design and safety analysis of direct cycle gas cooled reactor. The estimation of compressor and turbine performances in transient operations is of high importance for the designer. The first goal of this study is to provide a description of compressor behaviour in unstable conditions with a better understanding than the models based on performance maps ('traditional' 0D approach). A supplementary objective is to provide a coherent description of the turbine behaviour. The turbomachine modelling approach consists in the solution of 1D axisymmetric Navier-Stokes equations on an axial grid inside the turbomachine: mass, axial momentum, circumferential momentum and total-enthalpy balances are written. Blade forces are taken into account by using compressor or turbine blade cascade steady correlations. A particular effort has been developed to generate or test correlations in low mass flow and negative mass flow regimes, based on experimental data. The model is tested on open literature cases of the gas turbine aircraft community. For compressor and turbine, steady situations are fairly described, especially for medium and high mass flow rate. The dynamic behaviour of compressor is also quite well described, even in unstable operation (surge): qualitative tendencies (role of plenum volume and role of throttle) and some quantitative characteristics (frequency) are in a good agreement with experimental data. The application to transient simulations of gas cooled nuclear reactors is concentrated on the hypothetical 10 in. break accident. The results point out the importance of the location of the pipe rupture in a hypothetical break event. In some detailed cases, compressor surge and back flow through the circuit can occur. In order to be used in a design phase, a simplified model of surge has also been developed. This simplified model is applied to the gas fast reactor (GFR) and compared quite favourably with 1D axisymmetric simulation results
Thin circular cylinder under axisymmetrical thermal and mechanical loading
International Nuclear Information System (INIS)
Arnaudeau, F.; Zarka, J.; Gerij, J.
1977-01-01
To assess structural integrity of components subjected to cyclic thermal loadings one must look at thermal ratchetting as a possible failure mode. Considering a thin circular cylinder subjected to constant internal pressure and cyclically varying thermal gradient through the thickness Bree, J. Strain Analysis 2 (1967) No.3, obtained a diagram that serves as a foundation for many design rules (e.g.: ASME code). The upper part of the french LMFBR main vessel is subjected to an axisymmetrical axial thermal loading and an axial load (own weight). Operation of the reactor leads to cyclic variations of the axial thermal loading. The question that arises is whether or not the Bree diagram is realistic for such loading conditions. A special purpose computer code (Ratch) was developed to analyse a thin circular cylinder subjected to axisymmetrical mechanical and thermal loadings. The Mendelson's approach of this problem is followed. Classical Kirchoff-Love hypothesis of thin shells is used and a state of plane stress is assumed. Space integrations are performed by Gaussian quadrature in the axial direction and by Simpson's one third rule throughout the thickness. Thermoelastic-plastic constitutive equations are solved with an implicit scheme (Nguyen). Thermovisco-plastic constitutive equations are solved with an explicit time integration scheme (Treanor's algorithm especially fitted). A Bree type diagram is obtained for an axial step of temperature which varies cyclically and a sustained constant axial load. The material behavior is assumed perfectly plastic and creep effect is not considered. Results show that the domain where no ratchetting occurs is reduced when compared with the domain predicted by the Bree diagram
Secular instability of axisymmetric rotating stars to gravitational radiation reaction
International Nuclear Information System (INIS)
Managan, R.A.
1985-01-01
A generalization of the Eulerian variational principle derived by Ipser and Managan, for nonaxisymmetric neutral modes of axisymmetric fluid configurations, is developed. The principle provides a variational basis for calculating the frequencies of nonaxisymmetric normal modes proportional to e/sup i/(sigmat + mphi). A modified form of this principle, valid for sigma near 0, is also developed. The latter principle is used to locate the points where the frequency of a nonaxisymmetric normal mode of an axisymmetric rotating fluid configuration passes through zero. lt is at these points that the configuration becomes secularly unstable to gravitational radiation reaction (GRR). This is demonstrated directly by including the GRR potential and showing that the imaginary part of sigma passes through zero and becomes negative at these points. The imaginary part of the frequency is used to estimate the e-folding time of the mode. This variational principle is applied to sequences of rotating polytropes. The sequences are constructed using four rotation laws at each value of the polytropic index n = 0.5, 1.0, 1.5, 2.0, and 3.0. The values of (T/W)/sub m/, the ratio of the rotational kinetic energy to the magnitude of the gravitational potential energy at the onset of instability, and timescales for the modes with m = 2, 3, and 4 are estimated for each sequence. The value of (T/W) 2 is largely independent of the equation of state and rotation law. For m > 2, (T/W)/sub m/ decreases as the equation of state becomes softer, i.e., as the polytropic index n increases, and increases as the amount of differential rotation increases. The most striking result of this behavior occurs for uniform rotation
Emission and formation of electromagnetic pulses in cylindrical systems
International Nuclear Information System (INIS)
Lomize, L.G.; Sveshnikova, N.N.; Kuz'min, V.A.
1983-01-01
During the passage of a charged particle bunch through a cylindrical resonator after the process of field formation has been over the radiation, having separated from the intrinsic field, freely propagates over the resonator volume while undergoing multiple reflections from the resonator walls. As the numerical experiments have shown not only localized reflections from the resonator walls but the distributed reflections from the near-axial region take place; they result in the formation of a short intense pulse of the accelerating field along the resonator axis. The pulse runs in the direction of the bunch motion and is responsible for the process of particle autoacceleration. Transformations of the electromagnetic pUlse shape at subsequent reflections are rather of a regular character and repeated almost periodically in a certain period of time during which the light in the vacuum covers eight radii of the resonator. Conservation of the pulse shape from a period to another proceeds the more precisely, the shorter the range of the electromagnetic pulse is as compared with the resonator radius. If the resonator is permeated by successive bunches, then at a pulse frequency, for which the wave length is equal to eight radii of the resonator, a pulse resonance should arise, while at the wave length eqUal to four resonator radii a pulse antiresonance should arise
Amin, Muhammad
2014-07-01
The resonances with asymmetric Fano line-shapes were originally discovered in the context of quantum mechanics (U. Fano, Phys. Rev., 124, 1866-1878, 1961). Quantum Fano resonances were generated from destructive interference of a discrete state with a continuum one. During the last decade this concept has been applied in plasmonics where the interference between a narrowband polariton and a broader one has been used to generate electromagnetically induced transparency (EIT) (M. Rahmani, et al., Laser Photon. Rev., 7, 329-349, 2013).
An Electromagnetic Beam Converter
DEFF Research Database (Denmark)
2009-01-01
The present invention relates to an electromagnetic beam converter and a method for conversion of an input beam of electromagnetic radiation having a bell shaped intensity profile a(x,y) into an output beam having a prescribed target intensity profile l(x',y') based on a further development...
Classical electromagnetic radiation
Heald, Mark A
2012-01-01
Newly corrected, this highly acclaimed text is suitable for advanced physics courses. The author presents a very accessible macroscopic view of classical electromagnetics that emphasizes integrating electromagnetic theory with physical optics. The survey follows the historical development of physics, culminating in the use of four-vector relativity to fully integrate electricity with magnetism.
High frequency electromagnetic dosimetry
Sánchez-Hernández, David A
2009-01-01
Along with the growth of RF and microwave technology applications, there is a mounting concern about the possible adverse effects over human health from electromagnetic radiation. Addressing this issue and putting it into perspective, this groundbreaking resource provides critical details on the latest advances in high frequency electromagnetic dosimetry.
Electromagnetically Operated Counter
Goldberg, H D; Goldberg, M I
1951-12-18
An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.
Electromagnetic cyclotron harmonic waves
International Nuclear Information System (INIS)
Ohnuma, T.; Watanabe, T.; Hamamatsu, K.
1981-09-01
Electromagnetic electron cyclotron harmonic waves just below the electron cyclotron harmonics are investigated numerically and experimentally. Backward waves which are observed to propagate nearly perpendicular to the magnetic field just below the electron cyclotron frequency in a high density magnetoplasma are confirmed to be in accord with the theoretical electromagnetic cyclotron waves. (author)
Electromagnetic waves in optical fibres in a magnetic field
International Nuclear Information System (INIS)
Gorelik, V S; Burdanova, M G
2016-01-01
A new method is reported of recording the secondary radiation of luminescent substances based on the use of capillary fibres of great length. Theoretical analysis of the dispersion curves of electromagnetic radiation in capillary fibres doped with erbium ions Er 3+ has been established. The Lorentz model is used for describing the dispersion properties of electromagnetic waves in a homogeneous medium doped with rare-earth ions. The dispersion dependencies of polariton and axion–polariton waves in erbium nitrate hydrate are determined on the basis of the model of the interaction between electromagnetic waves and the resonance electronic states of erbium ions in the absence and presence of a magnetic field. (paper)
Electromagnetic Wave Chaos in Gradient Refractive Index Optical Cavities
International Nuclear Information System (INIS)
Wilkinson, P. B.; Fromhold, T. M.; Taylor, R. P.; Micolich, A. P.
2001-01-01
Electromagnetic wave chaos is investigated using two-dimensional optical cavities formed in a cylindrical gradient refractive index lens with reflective surfaces. When the planar ends of the lens are cut at an angle to its axis, the geometrical ray paths are chaotic. In this regime, the electromagnetic mode spectrum of the cavity is modulated by both real and ghost periodic ray paths, which also 'scar' the electric field intensity distributions of many modes. When the cavity is coupled to waveguides, the eigenmodes generate complex series of resonant peaks in the electromagnetic transmission spectrum
Energy Technology Data Exchange (ETDEWEB)
Chandrasekhar, S [Chicago Univ., Ill. (USA)
1976-02-10
Teukolsky's equation, governing the perturbations (scalar, electromagnetic, and gravitational) of the Kerr black hole, is transformed, by a simple change of variables, in a manner such that there is formally no difference in the treatments of the axisymmetric and the non-axisymmetric modes: the role of 'm' is effectively eliminated. By considering in detail the case of electromagentic perturbations it is shown how, in all cases, the problems can be reduced to problems in the theory of penetration of one dimensional potential barriers with, however, certain novel features. The phenomenon of super-radiance, peculiar to the Kerr metric, emerges, for example, in an unexpected guise. The case of scalar perturbations is considered briefly in an appendix.
Liu, Jianyong; Lu, Yajun; Li, Zhiping
2010-05-01
Non-axisymmetric wake impact experiments were carried out after the best exciting frequency for a low speed axial compressor had been found by axisymmetric wake impact experiments. When the number and circumferential distribution of inlet guide vanes (IGV) are logical the wakes of non-axisymmetric IGVs can exert beneficial unsteady exciting effect on their downstream rotor flow fields and improve the compressor’s performance. In the present paper, four non-axisymmetric wake impact plans were found working better than the axisymmetric wake impact plan. Compared with the base plan, the best non-axisymmetric plan increased the compressor’s peak efficiency, and the total pressure rise by 1.1 and 2%, and enhanced the stall margin by 4.4%. The main reason why non-axisymmetric plans worked better than the axisymmetric plan was explained as the change of the unsteady exciting signal arising from IGV wakes. Besides the high-frequency components, the non-axisymmetric plan generated a beneficial low-frequency square-wave exciting signal and other secondary frequency components. Compared with the axisymmetric plan, multi-frequency exciting wakes arising from the non-axisymmetric plans are easier to get coupling relation with complex vortices such as clearance vortices, passage vortices and shedding vortices.
A time-dependent dusty gas dynamic model of axisymmetric cometary jets
International Nuclear Information System (INIS)
Korosmezey, A.; Gombosi, T.I.
1990-01-01
The present time-dependent, axisymmetric dusty gas dynamical model of inner cometary atmospheres solves the coupled and time-dependent equations of continuity, momentum, and energy for a gas-dust mixture between the surface of the nucleus and 100 km, using an axisymmetric 40 x 40 grid structure. A novel numerical method employing a second-order accurate Godunov-type scheme with dimensional splitting is used to solve the time-dependent pde system. It is established that a subsolar dust spike not predicted by previous calculations is generated by narrow axisymmetric jets, together with a jet cone whose opening angle depends on the jet length. 28 refs
Partial Fourier analysis of time-harmonic Maxwell's equations in axisymmetric domains
International Nuclear Information System (INIS)
Nkemzi, Boniface
2003-01-01
We analyze the Fourier method for treating time-harmonic Maxwell's equations in three-dimensional axisymmetric domains with non-axisymmetric data. The Fourier method reduces the three-dimensional boundary value problem to a system of decoupled two-dimensional boundary value problems on the plane meridian domain of the axisymmetric domain. The reduction process is fully described and suitable weighted spaces are introduced on the meridian domain to characterize the two-dimensional solutions. In particular, existence and uniqueness of solutions of the two-dimensional problems is proved and a priori estimates for the solutions are given. (author)
International Nuclear Information System (INIS)
Choi, S. N.; Kim, H. N.; Jang, K. S.; Kim, H. J.
2000-01-01
The purpose of this paper is to determine a two dimensional axisymmetric model through a comparative study between a three dimensional and an axisymmetric finite element analysis of the reactor coolant piping nozzle subject to internal pressure. The finite element analysis results show that the stress adopting the axisymmetric model with the radius of equivalent spherical vessel are well agree with that adopting the three dimensional model. The radii of equivalent spherical vessel are 3.5 times and 7.3 times of the radius of the reactor coolant piping for the safety injection nozzle and for the residual heat removal nozzle, respectively
International Nuclear Information System (INIS)
Galishin, A.Z.
1995-01-01
The nonaxisymmetric thermoelastic stress-strain state (SSS) of branched laminar orthotropic shells was considered; the axisymmetric thermoviscoelastic SSS of branched laminar orthotropic shells was considered; and the axisymmetric thermoviscoelastoplastic SSS of branched laminar isotropic shells was considered, taking into account of the transverse-shear deformation. In the present work, in contrast, the axisymmetric thermoviscoelastoplastic SSS of branched laminar isotropic shells is considered, taking account of transverse-shear and torsional deformation. Layers that are made from orthotropic materials and deform in the elastic region may be present
Electromagnetic probes of the QGP
Directory of Open Access Journals (Sweden)
Bratkovskaya E. L.
2015-01-01
Full Text Available We investigate the properties of the QCD matter across the deconfinement phase transition in the scope of the parton-hadron string dynamics (PHSD transport approach. We present here in particular the results on the electromagnetic radiation, i.e. photon and dilepton production, in relativistic heavy-ion collisions. By comparing our calculations for the heavy-ion collisions to the available data, we determine the relative importance of the various production sources and address the possible origin of the observed strong elliptic flow v2 of direct photons. We argue that the different centrality dependence of the hadronic and partonic sources for direct photon production in nucleusnucleus collisions can be employed to shed some more light on the origin of the photon v2 “puzzle”. While the dilepton spectra at low invariant mass show in-medium effects like an enhancement from multiple baryonic resonance formation or a collisional broadening of the vector meson spectral functions, the dilepton yield at high invariant masses (above 1.1 GeV is dominated by QGP contributions for central heavy-ion collisions at ultra-relativistic energies. This allows to have an independent view on the parton dynamics via their electromagnetic massive radiation.
Electromagnetic form factors of hadrons
International Nuclear Information System (INIS)
Zidell, V.S.
1976-01-01
A vector meson dominance model of the electromagnetic form factors of hadrons is developed which is based on the use of unstable particle propagators. Least-square fits are made to the proton, neutron, pion and kaon form factor data in both the space and time-like regions. A good fit to the low-energy nucleon form factor data is obtained using only rho, ω, and phi dominance, and leads to a determination of the vector meson resonance parameters in good agreement with experiment. The nucleon-vector meson coupling constants obey simple sum rules indicating that there exists no hard core contribution to the form factors within theoretical uncertainties. The prediction for the electromagnetic radii of the proton is in reasonable agreement with recent experiments. The pion and kaon charge form factors as deduced from the nucleon form factors assuming vector meson universality are compared to the data. The pion form factor agrees with the data in both the space and time-like regions. The pion charge radius is in agreement with the recent Dubna result, but the isovector P-wave pion-pion phase shift calculated from the theory disagrees with experiment. A possible contribution to the form factors from a heavy rho meson is also evaluated
Reducing radar cross section by investigation electromagnetic materials
Directory of Open Access Journals (Sweden)
S. Komeylian
2012-12-01
Full Text Available Decreasing the Radar Cross Section (RCS is investigated in electromagnetic materials, i.e. double-positive (DPS , double-negative (DNG , epsilon-negative (ENG and mu-negative (MNG materials. The interesting properties of these materials lead to a great flexibility in manufacturing structures with unusual electromagnetic characteristics. The valid conditions for achieving the transparency and gaining resonance for an electrically small cylinder are established, in this corresponding The effect of incidence direction on RCS inclusive of transparency and resonance conditions is also explored ,through computer simulations for an electrically small cylinder.
Energy Technology Data Exchange (ETDEWEB)
Courtois, L
2001-03-09
Electron cyclotron resonance heating (ECRH) in the Tore Supra tokamak constitutes an important step in the research aimed at obtaining thermonuclear fusion reactions. Electron heating is achieved by transmitting an electromagnetic wave from the oscillators (gyrotrons) to the plasma via the fundamental mode, propagating in oversized corrugated waveguides. Maximizing the proportion of the gyrotron power coupled to the fundamental waveguide mode is essential for the good functioning of the transmission line and for maximizing the effect on the plasma. This thesis gives all necessary tools for finding the proportion of the fundamental mode and all other modes present in passive components and at the output of the gyrotron as installed in the Tore Supra ECRH plant. This characterisation is based on obtaining amplitude and phase diagrams of the electric field on a plane transverse to the propagation axis. The most difficult part of obtaining these diagrams is measuring the phase which, despite the very short wavelength, is measured directly at low power levels. At high power levels the phase is numerically reconstructed from amplitude measurements for gyrotron characterisation. A complete theoretical study of the phase reconstruction code is given including its validation with theoretical diagrams. This study allows the realisation of a modal characterisation unit electromagnetic for measurement of radiated beams and usable in each part of the ECRH installation. At the end, the complete modal characterisation is given at low level for a mode converter and also at high level for the first series gyrotron installed at TORE SUPRA. (author)
International Nuclear Information System (INIS)
Takahashi, Kenji.
1994-01-01
As an electromagnetic shaft seal, there are disposed outwarding electromagnetic induction devices having generating power directing to an electroconductive fluid as an object of sealing, and inwarding electromagnetic induction device added coaxially. There are disposed elongate rectangular looped first coils having a predetermined inner diameter, second coils having the same shape and shifted by a predetermined pitch relative to the first coil and third coil having the same shape and shifted by a predetermined pitch relative to the second coil respectively each at a predetermined inner diameter of clearance to the outwarding electromagnetic induction devices and the inwarding electromagnetic induction device. If the inwarding electromagnetic induction device and the outwarding electromagnetic induction device are operated, they are stopped at a point that the generating power of the former is equal with the sum of the generating power of the latter and a differential pressure. When three-phase AC is charged to the first coil, the second coil and the third coil successively, a force is generated in the advancing direction of the magnetic field in the electroconductive fluid by the similar effect to that of a linear motor, and the seal is maintained at high reliability. Moreover, the limit for the rotational angle of the shaft is not caused. (N.H.)
Model for resonant plasma probe.
Energy Technology Data Exchange (ETDEWEB)
Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue
2007-04-01
This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.
Curved electromagnetic missiles
International Nuclear Information System (INIS)
Myers, J.M.; Shen, H.M.; Wu, T.T.
1989-01-01
Transient electromagnetic fields can exhibit interesting behavior in the limit of great distances from their sources. In situations of finite total radiated energy, the energy reaching a distant receiver can decrease with distance much more slowly than the usual r - 2 . Cases of such slow decrease have been referred to as electromagnetic missiles. All of the wide variety of known missiles propagate in essentially straight lines. A sketch is presented here of a missile that can follow a path that is strongly curved. An example of a curved electromagnetic missile is explicitly constructed and some of its properties are discussed. References to details available elsewhere are given
Electromagnetic spatial coherence wavelets
International Nuclear Information System (INIS)
Castaneda, R.; Garcia-Sucerquia, J.
2005-10-01
The recently introduced concept of spatial coherence wavelets is generalized for describing the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows analyzing the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides a further insight about the causal relationship between the polarization states at different planes along the propagation path. (author)
Nonlinear surface electromagnetic phenomena
Ponath, H-E
1991-01-01
In recent years the physics of electromagnetic surface phenomena has developed rapidly, evolving into technologies for communications and industry, such as fiber and integrated optics. The variety of phenomena based on electromagnetism at surfaces is rich and this book was written with the aim of summarizing the available knowledge in selected areas of the field. The book contains reviews written by solid state and optical physicists on the nonlinear interaction of electromagnetic waves at and with surfaces and films. Both the physical phenomena and some potential applications are
Kim, Daejoong; Gil, Y. S.; Chung, TaeWon; Chung, Suk-Ho
2009-01-01
The stabilization characteristics of premixed flames in an axisymmetric curved-wall jet burner have been experimentally investigated. This burner utilized the Coanda effect on top of a burner tip. The initially spherical burner tip was modified to a
International Nuclear Information System (INIS)
Parsa, Z.; Serafini, L.
1992-04-01
This note provides a sketch of the formalism used for the Integration of Transients in Axisymmetrical Cavities for Accelerators, (ITACA). Application to study the BNL Photocathode Gun via the code ITACA is also included
Computation of steady and unsteady compressible quasi-axisymmetric vortex flow and breakdown
Kandil, Osama A.; Kandil, Hamdy A.; Liu, C. H.
1991-01-01
The unsteady, compressible Navier-Stokes equations are used to compute and analyze compressible quasi-axisymmetric isolated vortices. The Navier-Stokes equations are solved using an implicit, upwind, flux-difference splitting finite-volume scheme. The developed three-dimensional solver has been verified by comparing its solution profiles with those of a slender, quasi-axisymmetric vortex solver for a subsonic, isolated quasi-axisymmetric vortex in an unbounded domain. The Navier-Stokes solver is then used to solve for a supersonic quasi-axisymmetric vortex flow in a configured circular duct. Steady and unsteady vortex-shock interactions and breakdown have been captured. The problem has also been calculated using the Euler solver of the same code and the results are compared with those of the Navier-Stokes solver. The effect of the initial swirl has been tentatively studied.
Computation of compressible quasi-axisymmetric slender vortex flow and breakdown
Kandil, Osama A.; Kandil, Hamdy A.
1991-01-01
The unsteady, compressible Navier-Stokes equations are used to compute and analyze compressible quasi-axisymmetric isolated vortices. The Navier-Stokes equations are solved using an implicit, upwind, flux difference splitting finite volume scheme. The developed three dimensional solver was verified by comparing its solution profiles with those of a slender, quasi-axisymmetric vortex solver for a subsonic, quasi-axisymmetric vortex in an unbounded domain. The Navier-Stokes solver is then used to solve for a supersonic, quasi-axisymmetric vortex flow in a configured circular duct. Steady and unsteady vortex-shock interactions and breakdown were captured. The problem was also calculated using the Euler solver of the same code; the results were compared with those of the Navier-Stokes solver. The effect of the initial swirl was investigated.
Elastic-plastic analysis of an axi-symmetric problem by a finite element method
International Nuclear Information System (INIS)
Isozaki, Toshikuni
1984-06-01
Generally speaking, many structures are designed and fabricated on the basis of an axi-symmetric structure. Finite Element Method is the capable method to solve these axi-symmetric problems beyond the elastic limit. As the first step to solve these problems, the computer program for the elastic-plastic analysis of the axi-symmetric problem is composed. The basic program is based upon that described in Zienkiewicz's text book to solve the elastic plane stress problem, taking the plastic stress matrix by Yamada's method into consideration and it is converted to solve the axi-symmetric problem. For the verification of the program, the plane strain problem of a cylindrical tube under internal pressure was solved. The computed results were compared with those shown in ADINA's user's manual. They showed close agreement. (author)
Lyapunov stability analysis of magnetohydrodynamic plasma equilibria with axisymmetric toroidal flow
International Nuclear Information System (INIS)
Almaguer, J.A.; Hameiri, E.; Herrera, J.; Holm, D.D.
1988-01-01
Lyapunov stability conditions for ideal magnetohydrodynamic (MHD) plasmas with mass flow in axisymmetric toroidal geometry are determined in the Eulerian representation. Axisymmetric equilibrium solutions of ideal MHD are associated to critical points of a nonlinearly conserved Lyapunov functional consisting of the sum of the total energy and the following flux-weighted quantities: the circulation along field lines, the angular momentum, the toroidal flux, and the mass content within each flux tube. Conditions sufficient for Lyapunov stability of these equilibria against axisymmetric perturbations are found by taking advantage of the Hamiltonian formalism for ideal MHD. In particular [see Eq. (60)], it is sufficient for Lyapunov stability under linearized dynamics that an axisymmetric equilibrium be subsonic in the appropriate rotating frame, lie in the first elliptic regime of the Bernoulli--Grad--Shafranov (BGS) system of equations, and satisfy one additional, more complicated, condition. Effects of boundary conditions, nonlinearity, and three-dimensionality on MHD stability are also discussed
International Nuclear Information System (INIS)
Tagirov, Eh.A.
1985-01-01
A model of resonance parametric transformation of a gravitational wave to electromagnetic one is considered. Two plane monochromatic waves: a strong electromagnetic and weak gravitational - interacting in a medium generate at difference and sum frequencies an electromagnetic wave in a direction determined with the condition of spatial wave synchronism. Rarefied cold gas or beam of elementary emitters (''molecules'') serve as a medium model. Coefficients of parametric transformation have been determined
Effect of compressibility on the global stability of axisymmetric wake flows
Meliga , Philippe; Sipp , D.; Chomaz , Jean-Marc
2010-01-01
International audience; We study the linear dynamics of global eigenmodes in compressible axisymmetric wake flows, up to the high subsonic regime. We consider both an afterbody flow at zero angle of attack and a sphere, and find that the sequence of bifurcations destabilizing the axisymmetric steady flow is independent of the Mach number and reminiscent of that documented in the incompressible wake past a sphere and a disk (Natarajan & Acrivos, J. Fluid Mech., vol. 254, 1993, p. 323), hence s...
Flock, M.; Ruge, J. P.; Dzyurkevich, N.; Henning, Th.; Klahr, H.; Wolf, S.
2014-01-01
International audience; Aims. Recent observations by the Atacama Large Millimeter/submillimeter Array (ALMA) of disks around young stars revealed distinct asymmetries in the dust continuum emission. In this work we wish to study axisymmetric and non-axisymmetric structures that are generated by the magneto-rotational instability in the outer regions of protoplanetary disks. We combine the results of state-of-the-art numerical simulations with post-processing radiative transfer (RT) to generat...
On absorption of low frequency electromagnetic fields
International Nuclear Information System (INIS)
Brunner, S.; Vaclavik, J.
1993-03-01
The drift kinetic equation (DKE) is used to establish a formula for power absorption of small amplitude, low frequency electromagnetic (EM) fields in a hot toroidal axisymmetric plasma. The stationary plasma is first considered. Electrons and ions are described by local Maxwellian distributions, alpha particles by a local slowing-down distribution. The fluctuating part of the distribution function for each species is then evaluated from the linearized DKE in terms of the EM fields using a perturbation method. The parameter b p =B p /B o , where B p is the poloidal component of the magnetostatic field B o , and the parameter v d /λω, where v d is the magnetic curvature drift, λ the wavelength perpendicular to B o and ω the frequency of the EM fields, are considered to be small. By integrating the resulting distribution function over velocity space, an explicit formula for the power absorbed by each species is obtained. To obtain an expression suitable for direct implementation in an ideal-MHD code, the electric field component parallel to the magnetostatic field is evaluated using the quasi-neutrality equation. (author) 4 refs
Statistical electromagnetics: Complex cavities
Naus, H.W.L.
2008-01-01
A selection of the literature on the statistical description of electromagnetic fields and complex cavities is concisely reviewed. Some essential concepts, for example, the application of the central limit theorem and the maximum entropy principle, are scrutinized. Implicit assumptions, biased
Broadband Electromagnetic Technology
2011-06-23
The objectives of this project are to continue the enhancements to the combined Broadband Electromagnetic and Full Encirclement Unit (BEM-FEU) technologies and to evaluate the systems capability in the laboratory and the field. The BEM instrument ...
Magnetorheological suspension electromagnetic brake
International Nuclear Information System (INIS)
Bica, Ioan
2004-01-01
The magnetorheological suspension (MRS) brake is of the monoblock type. The main part of the electromagnetic brake is an electromagnet, between whose poles two MRS disks are placed. For distances between disks of 0.65x10 -3 m±10%, revolutions of the electric motor, coupled to the electromagnetic brake, ranging between 200 and 1600 rev/min and braking powers of up to 85 W, there are no differences in revolutions between the disks of the electromagnetic brake. For fixed revolutions of the electric motor, the revolution of the parallel disk can be modified continuously by means of the intensity of the magnetic field. In all cases, the quantity of MRS is of 0.35x10 -3 kg
Computational electromagnetic-aerodynamics
Shang, Joseph J S
2016-01-01
Presents numerical algorithms, procedures, and techniques required to solve engineering problems relating to the interactions between electromagnetic fields, fluid flow, and interdisciplinary technology for aerodynamics, electromagnetics, chemical-physics kinetics, and plasmadynamics This book addresses modeling and simulation science and technology for studying ionized gas phenomena in engineering applications. Computational Electromagnetic-Aerodynamics is organized into ten chapters. Chapter one to three introduce the fundamental concepts of plasmadynamics, chemical-physics of ionization, classical magnetohydrodynamics, and their extensions to plasma-based flow control actuators, high-speed flows of interplanetary re-entry, and ion thrusters in space exploration. Chapter four to six explain numerical algorithms and procedures for solving Maxwell’s equation in the time domain for computational electromagnetics, plasma wave propagation, and the time-dependent c mpressible Navier-Stokes equation for aerodyn...
OPAL detector electromagnetic calorimeter
1988-01-01
Half of the electromagnetic calorimeter of the OPAL detector is seen in this photo. This calorimeter consists of 4720 blocks of lead glass. It was used to detect and measure the energy of photons, electrons and positrons by absorbing them.
The classical electromagnetic field
Eyges, Leonard
2010-01-01
This excellent text covers a year's course in advanced theoretical electromagnetism, first introducing theory, then its application. Topics include vectors D and H inside matter, conservation laws for energy, momentum, invariance, form invariance, covariance in special relativity, and more.
Electromagnetic-acoustic coupling in ferromagnetic metals at liquid-helium temperatures
DEFF Research Database (Denmark)
Gordon, R A
1981-01-01
Electromagnetic-acoustic coupling at the surface and in the bulk of ferromagnetic metals at liquid-helium temperatures has been studied using electromagnetically excited acoustic standing-wave resonances at MHz frequencies in a number of ferromagnetic metals and alloys of commercial interest...
High frequency electromagnetic processes in induction motors supplied from PWM inverters
Directory of Open Access Journals (Sweden)
Ioan Ţilea
2010-12-01
Full Text Available The paper presents the electromagnetic interference between induction motors and inverters when at high frequency electromagnetic process appears in induction motors having a parallel resonant effect because of parasitic capacitive coupling between windings and ground, using a numerical model in simulink and a high frequency induction motor equivalent circuit model this effect is shown.
First integrals of the axisymmetric shape equation of lipid membranes
Zhang, Yi-Heng; McDargh, Zachary; Tu, Zhan-Chun
2018-03-01
The shape equation of lipid membranes is a fourth-order partial differential equation. Under the axisymmetric condition, this equation was transformed into a second-order ordinary differential equation (ODE) by Zheng and Liu (Phys. Rev. E 48 2856 (1993)). Here we try to further reduce this second-order ODE to a first-order ODE. First, we invert the usual process of variational calculus, that is, we construct a Lagrangian for which the ODE is the corresponding Euler–Lagrange equation. Then, we seek symmetries of this Lagrangian according to the Noether theorem. Under a certain restriction on Lie groups of the shape equation, we find that the first integral only exists when the shape equation is identical to the Willmore equation, in which case the symmetry leading to the first integral is scale invariance. We also obtain the mechanical interpretation of the first integral by using the membrane stress tensor. Project supported by the National Natural Science Foundation of China (Grant No. 11274046) and the National Science Foundation of the United States (Grant No. 1515007).
Thin circular cylinder under axisymmetrical thermal and mechanical loading
International Nuclear Information System (INIS)
Arnaudeau, F.; Zarka, J.; Gerij, J.
1977-01-01
A special purpose computer code (Ratch) was developed to analyse a thin circular cylinder subjected to axisymmetrical mechanical and thermal loadings. The Mendelson's approach of this problem is followed. Classical Kirchoff-Love hypothesis of thin shells is used and a state of plane stress is assumed. Space integrations are performed by Gaussian quadrature in the axial direction and by Simpson's one third rule throughout the thickness. Thermoelastic-plastic constitutive equations are solved with an implicit scheme (Nguyen). Thermovisco-plastic constitutive equations are solved with an explicit time integration scheme (Treanor's algorithm especially fitted). A Bree type diagram is obtained for an axial step of temperature which varies cyclically and a sustained constant axial load. The material behavior is assumed perfectly plastic and creep effect is not considered. Results show that the domain where ratchetting occurs is reduced when compared with the domain predicted by the Bree diagram. To investigate the effect of material hardening the authors verify Halphen's Theorem which states that a structure made of material with kinematic hardening behavior and constant properties with temperature will always shake down to a periodic behavior. (Auth.)
Plasma equilibria and stationary flows in axisymmetric systems. Pt. 3
International Nuclear Information System (INIS)
Zelazny, R.; Stankiewicz, R.; Galkowski, A.; Potempski, S.; Pietak, R.
1990-08-01
The problem of the importance of poloidal flows for the behaviour of plasmas in axisymmetric systems has caused a lot of discussion and controversy during the last 15 years. There is no doubt that the mere existence of poloidal flow transforms the elliptic Grad-Shafranov-Schlueter equation into a system of mixed type partial differential equation and an algebraic multivalued Bernoulli equation. This fact leads to the appearance of Bernoulli branches in the solutions. Then, one can come across three branches of elliptic solutions as well as two branches of hyperbolic solutions with the possible appearance of phenomena connected with ''transsonic'' effects. Problems connected with such a mathematical situation have been extensively discussed in the report with the same title, dated May 1988, which we shall call later Part I of our studies on this subject. The present report, considered as Part III, is devoted to the presentation of results of efforts aimed at constructing programmes which allow us to solve the extended Grad-Shafranov-Schlueter equation (EGSS) (with stationary flows) in a more realistic situation relevant to the JET operating conditions. The main problem is to specify for a wider class of profiles the boundary conditions at the magnetic axis for a system of nonlinear ordinary differential equations ODE, resulting from EGSS equation after application of Fourier transformation techniques and of inverse method approach. The present report elaborates a much more general case and describes the computational framework enabling us to derive those boundary conditions. (author)
Linear theory of the tearing instability in axisymmetric toroidal devices
International Nuclear Information System (INIS)
Rogister, A.; Singh, R.
1988-08-01
We derive a very general kinetic equation describing the linear evolution of low m/l modes in axisymmetric toroidal plasmas with arbitrary cross sections. Included are: Ion sound, inertia, diamagnetic drifts, finite poloidal beta, and finite ion Larmor radius effects. Assuming the magnetic surfaces to form a set of nested tori with circular cross sections of shifted centers, and introducing adequate simplifications justified by our knowledge of experimental tokamak plasmas, we then obtain explicitely the sets of equations describing the coupling of the quasimodes 0/1, 1/1, 2/1, and, for m≥2, m/1, (m+1)/1. By keeping finite aspect ratio effects into account when calculating the jump of the derivative of the eigenfunction, it is shown that the theory can explain the rapid evolution, within one sawtooth period, of the growth rate of the sawteeth precursors from resistive values to magnetohydrodynamic ones. The characteristics thus theoretically required from current profiles in sawtoothing discharges have clearly been observed. Other aspects of the full theory could be relevant to the phenomenon of major disruptions. (orig.)
The Poisson equation in axisymmetric domains with conical points
International Nuclear Information System (INIS)
Nkemzi, B.
2003-01-01
This paper analyzes the application of the Fourier-finite-element method (FFEM) for the resolution of the Derichlet problem for the Poisson equation -Δu-circumflex = f-circumflex in axisymmetric domains Ω-circumflex subset of R 3 with conical points on the rotation axis. The FFEM combines the approximate Fourier method with respect to one space direction with the finite element method for the approximate calculation of the Fourier coefficients of the solution. Here, the influence of the conical points on the regularity of the Fourier coefficients of the solution is analyzed and the asymptotic behaviour of the coefficients near the conical points is described by some singularity functions and treated numerically by mesh grading in the two-dimensional meridian of Ω-circumflex. It is proved that for f-circumflex in L 2 (Ω-circumflex), the rate of convergence of the combined approximations in the Sobolev space W 2 1 (Ω-circumflex) is of the order O(h + N -1 ), where h and N represent, respectively, the parameters of the finite-element- and the Fourier-approximation, with h → 0 and n → ∞. (author)
Axisymmetric core collapse simulations using characteristic numerical relativity
International Nuclear Information System (INIS)
Siebel, Florian; Mueller, Ewald; Font, Jose A.; Papadopoulos, Philippos
2003-01-01
We present results from nonrotating axisymmetric stellar core collapse simulations in general relativity. Our hydrodynamics code has proved robust and accurate enough to allow for a detailed analysis of the global dynamics of the collapse. Contrary to traditional approaches based on the 3+1 formulation of the gravitational field equations, our framework uses a foliation based on a family of outgoing light cones, emanating from a regular center, and terminating at future null infinity. Such a coordinate system is well adapted to the study of interesting dynamical spacetimes in relativistic astrophysics such as stellar core collapse and neutron star formation. Perhaps most importantly this procedure allows for the extraction of gravitational waves at future null infinity, along with the commonly used quadrupole formalism for the gravitational wave extraction. Our results concerning the gravitational wave signals show noticeable disagreement when those are extracted by computing the Bondi news at future null infinity on the one hand and by using the quadrupole formula on the other hand. We have a strong indication that for our setup the quadrupole formula on the null cone does not lead to physical gravitational wave signals. The Bondi gravitational wave signals extracted at infinity show typical oscillation frequencies of about 0.5 kHz
Magnetohydrodynamic equilibria and local stability of axisymmetric tokamak plasmas
International Nuclear Information System (INIS)
Peng, Y.K.M.; Dory, R.A.; Nelson, D.B.; Sayer, R.O.
1976-07-01
Axisymmetric magnetohydrodynamic equilibria are evaluated in terms of the Mercier Stability Criterion. The parameters of interest include poloidal beta (β/sub p/), current and pressure profile widths, D-shaped and doublet plasmas with elongation (sigma) and triangularity (delta), and the aspect ratio (A). For marginal local stability, the critical values of β, plasma current, and the safety factor q with fixed toroidal field at the geometric center of the plasma are obtained. It is shown that for a wide range of profiles in a D-shaped plasma with A = 3, the highest critical β occurs at β/sub p/ = 2.4, sigma = 1.65, and delta = 0.5. If the toroidal field at the coil surface is fixed, the highest critical pressure occurs near A approximately 3 to 4, given reasonable distance between the coils and the plasma edge. Calculations for a Doublet II-A plasma with sigma = 3 show that with similar pressure profile the highest critical β occurs at β/sub p/ = 1 and is 84 percent of the highest critical β for the D-shaped plasmas. Critical values of ohmic heating power density are also found to be comparable for the two plasma shapes. A D-shaped plasma with the above parameters is suggested for use in future high-β tokamak devices
Characterization of axisymmetric disruption dynamics toward VDE avoidance in tokamaks
International Nuclear Information System (INIS)
Nakamura, Y.
2002-01-01
Disruption experiments on Alcator C-Mod and ASDEX-Upgrade tokamaks and axisymmetric MHD simulations using the TSC have explicated the underlying mechanisms of Vertical Displacement Events (VDEs) and a diversity of disruption dynamics. First, the neutral point, which is known as an initial vertical plasma position advantageous to VDE avoidance, is shown to be fairly insensitive to plasma shape and current profile parameters, while the VDE rate significantly depends on those parameters. Secondly, it is clarified that a rapid flattening of the plasma current profile frequently seen at the thermal quench drags a single null-diverted, up-down asymmetric plasma vertically toward divertor, whereas the dragging effect is absent in up-down symmetric limiter discharges. As a consequence, the occurrence of downward-going VDEs predominates over the upward-going ones in bottom-diverted discharges, being consistent with experiments in ASDEX-Upgrade. Together with the attractive force that arises from passive shell currents induced by the current quench and vanishes at the neutral point, the dragging effect explains many details of the VDE dynamics over the whole period of disruptive termination. (author)
Characterization of axisymmetric disruption dynamics toward VDE avoidance in tokamaks
International Nuclear Information System (INIS)
Nakamura, Y.; Yoshino, R.; Granetz, R.S.; Pautasso, G.; Gruber, O.; Jardin, S.C.
2003-01-01
Experiments and axisymmetric MHD simulations on tokamak disruptions have explicated the underlying mechanisms of Vertical Displacement Events (VDEs) and a diversity of disruption dynamics. First, the neutral point, which is known as an advantageous vertical plasma position to avoiding VDEs during the plasma current quench, is shown to be fairly insensitive to plasma shape and current profile parameters. Secondly, a rapid flattening of the plasma current profile frequently seen at thermal quench is newly clarified to play a substantial role in dragging a single null-diverted plasma vertically towards the divertor. As a consequence, the occurrence of downward-going VDEs predominates over the upward-going ones in bottom diverted discharges. This dragging effect is absent in up-down symmetric limiter discharges. These simulation results are consistent with experiments. Together with the attractive force that arises from passive shell currents and essentially vanishes at the neutral point, the dragging effect explains many details of the VDE dynamics over the whole period of the disruptive termination. (author)
Axisymmetric bifurcations of thick spherical shells under inflation and compression
deBotton, G.; Bustamante, R.; Dorfmann, A.
2013-01-01
Incremental equilibrium equations and corresponding boundary conditions for an isotropic, hyperelastic and incompressible material are summarized and then specialized to a form suitable for the analysis of a spherical shell subject to an internal or an external pressure. A thick-walled spherical shell during inflation is analyzed using four different material models. Specifically, one and two terms in the Ogden energy formulation, the Gent model and an I1 formulation recently proposed by Lopez-Pamies. We investigate the existence of local pressure maxima and minima and the dependence of the corresponding stretches on the material model and on shell thickness. These results are then used to investigate axisymmetric bifurcations of the inflated shell. The analysis is extended to determine the behavior of a thick-walled spherical shell subject to an external pressure. We find that the results of the two terms Ogden formulation, the Gent and the Lopez-Pamies models are very similar, for the one term Ogden material we identify additional critical stretches, which have not been reported in the literature before.© 2012 Published by Elsevier Ltd.
Direct numerical simulation of axisymmetric laminar low-density jets
Gomez Lendinez, Daniel; Coenen, Wilfried; Sevilla, Alejandro
2017-11-01
The stability of submerged laminar axisymmetric low-density jets has been investigated experimentally (Kyle & Sreenivasan 1993, Hallberg & Strykowski 2006) and with linear analysis (Jendoubi & Strykowski 1994, Coenen & Sevilla 2012, Coenen et al. 2017). These jets become globally unstable when the Reynolds number is larger than a certain critical value which depends on the density ratio and on the velocity profile at the injector outlet. In this work, Direct Numerical Simulations using FreeFEM + + (Hecht 2012) with P1 elements for pressure and P2 for velocity and density are performed to complement the above mentioned studies. Density and velocity fields are analyzed at long time showing the unforced space-time evolution of nonlinear disturbances propagating along the jet. Using the Stuart-Landau model to fit the numerical results for the self-excited oscillations we have computed a neutral stability curve that shows good agreement with experiments and stability theory. Thanks to Spanish MINECO under projects DPI2014-59292-C3-1-P and DPI2015-71901-REDT for financial support.
Calculation of transport coefficients in an axisymmetric plasma
International Nuclear Information System (INIS)
Shumaker, D.E.
1976-01-01
A method of calculating the transport coefficient in an axisymmetric toroidal plasma is presented. This method is useful in calculating the transport coefficients in a Tokamak plasma confinement device. The particle density and temperature are shown to be a constant on a magnetic flux surface. Transport equations are given for the total particle flux and total energy flux crossing a closed toroidal surface. Also transport equations are given for the toroidal magnetic flux. A computer code was written to calculate the transport coefficients for a three species plasma, electrons and two species of ions. This is useful for calculating the transport coefficients of a plasma which contains impurities. It was found that the particle and energy transport coefficients are increased by a large amount, and the transport coefficients for the toroidal magnetic field are reduced by a small amount. For example, a deuterium plasma with 1.3 percent oxygen, one of the particle transport coefficients is increased by a factor of about four. The transport coefficients for the toroidal magnetic flux are reduced by about 20 percent. The increase in the particle transport coefficient is due to the collisional scattering of the deuterons by the heavy oxygen ions which is larger than the deuteron electron scattering, the normal process for particle transport in a two species plasma. The reduction in the toroidal magnetic flux transport coefficients are left unexplained
Axisymmetric toroidal equilibrium with flow and anisotropic pressure
International Nuclear Information System (INIS)
Iacono, R.; Bondeson, A.; Troyon, F.; Gruber, R.
1989-10-01
Axisymmetric toroidal plasma equilibria with mass flows and anisotropic pressure are investigated. The equilibrium system is derived for a general functional form of the pressures, which includes both fluid models, such as the magnetohydrodynamic (MHD) and the double-adiabatic models, and Grad's guiding centre model. This allows for detailed comparisons between the models and clarifies how the 'first hyperbolic region', occurring in the fluid theory when the poloidal flow is of the order of the poloidal sound speed, can be eliminated in guiding centre theory. In the case of a pure toroidal rotation, macroscopic equations of state are derived from the guiding centre model, characterized by a parallel temperature that is constant on each magnetic surface and a perpendicular temperature that varies with the magnetic field. The outward centrifugal shifts of the magnetic axis and of the mass density profile, due to toroidal rotation, are increased by anisotropy. The guiding centre model shows that poloidal flow produces an inward shift of the density profile, in contrast with the MHD result. (author) 1 fig., 1 tab., 17 refs
Plasma equilibria and stationary flows in axisymmetric systems. Pt. 1
International Nuclear Information System (INIS)
Zelazny, R.; Stankiewicz, R.; Potempski, S.
1988-05-01
During discharges within a tokamak device such as JET fluctuations are observed in the plasma, of plasma density, temperature, electric potential and of the magnetic field. These fluctuations have complicated structure and are linked with different kinds of instabilities. However, it is not clear which instabilities are most important in determining the behaviour of the plasma. A comprehensive numerical theory which can predict the effect of the instabilities on the transport of plasma in axisymmetric systems has been sought using the static Grad-Shafranov-Schlueter (SGSS) equation as a basis. However, the static equation was over simplified for the situation in JET with additional heating giving rise to large toroidal flows, and an extended equation (EGSS) was developed. The results of the study include the discovery of algebraic branches of solutions to the EGSS equation even for very small poloidal flows, solutions to the inverse problem for the SGSS and EGSS equations using Fourier decomposition, classification of the boundary condition at the magnetic axis, demonstration of a visible effect of the poloidal flow on the separation of the density surface and the magnetic surface an indication of the existence of multiple branches of solutions to the EGSS and SGSS equations and their relation to stability properties. (U.K.)
Wave scattering by an axisymmetric ice floe of varying thickness
Bennetts, Luke G.; Biggs, Nicholas R. T.; Porter, David
2009-04-01
The problem of water wave scattering by a circular ice floe, floating in fluid of finite depth, is formulated and solved numerically. Unlike previous investigations of such situations, here we allow the thickness of the floe (and the fluid depth) to vary axisymmetrically and also incorporate a realistic non-zero draught. A numerical approximation to the solution of this problem is obtained to an arbitrary degree of accuracy by combining a Rayleigh-Ritz approximation of the vertical motion with an appropriate variational principle. This numerical solution procedure builds upon the work of Bennets et al. (2007, J. Fluid Mech., 579, 413-443). As part of the numerical formulation, we utilize a Fourier cosine expansion of the azimuthal motion, resulting in a system of ordinary differential equations to solve in the radial coordinate for each azimuthal mode. The displayed results concentrate on the response of the floe rather than the scattered wave field and show that the effects of introducing the new features of varying floe thickness and a realistic draught are significant.
Mathematics and electromagnetism
International Nuclear Information System (INIS)
Rodriguez Danta, M.
2000-01-01
Symbiosis between mathematics and electromagnetism is analyzed in a simple and concise manner by taking a historical perspective. The universal tool character of mathematical models allowed the transfer of models from several branches of physics into the realm of electromagnetism by drawing analogies. The mutual interdependence between covariant formulation and tensor calculus is marked. The paper focuses on the guiding idea of field theory and Maxwell's equations. Likewise, geometrization of interactions in connection with gauge fields is also noted. (Author)
The ATLAS electromagnetic calorimeter
Maximilien Brice
2003-01-01
Michel Mathieu, a technician for the ATLAS collaboration, is cabling the ATLAS electromagnetic calorimeter's first end-cap, before insertion into its cryostat. Millions of wires are connected to the electromagnetic calorimeter on this end-cap that must be carefully fed out from the detector so that data can be read out. Every element on the detector will be attached to one of these wires so that a full digital map of the end-cap can be recreated.
Electromagnetic Fields Exposure Limits
2018-01-01
Mr. T.P. (Tjerk) KUIPERS Senior Adviser Health Physics Military Healthcare & Occupational Health Expertise Co-ordination Centre Support...Test of Biological Integrity in Dogs Exposed to an Electromagnetic Pulse Environment”, Health Physics 36:159-165, 1979. [11] Baum, S.J., Ekstrom, M.E...Electromagnetic Radiation”, Health Physics 30:161-166, 1976. [12] Baum, S., Skidmore, W. and Ekstrom, M., “Continuous Exposure of Rodents to 108 Pulses
Electromagnetic Manifestation of Earthquakes
Uvarov Vladimir
2017-01-01
In a joint analysis of the results of recording the electrical component of the natural electromagnetic field of the Earth and the catalog of earthquakes in Kamchatka in 2013, unipolar pulses of constant amplitude associated with earthquakes were identified, whose activity is closely correlated with the energy of the electromagnetic field. For the explanation, a hypothesis about the cooperative character of these impulses is proposed.
Electromagnetic Manifestation of Earthquakes
Directory of Open Access Journals (Sweden)
Uvarov Vladimir
2017-01-01
Full Text Available In a joint analysis of the results of recording the electrical component of the natural electromagnetic field of the Earth and the catalog of earthquakes in Kamchatka in 2013, unipolar pulses of constant amplitude associated with earthquakes were identified, whose activity is closely correlated with the energy of the electromagnetic field. For the explanation, a hypothesis about the cooperative character of these impulses is proposed.
Electromagnetic reverberation chambers
Besnier, Philippe
2013-01-01
Dedicated to a complete presentation on all aspects of reverberation chambers, this book provides the physical principles behind these test systems in a very progressive manner. The detailed panorama of parameters governing the operation of electromagnetic reverberation chambers details various applications such as radiated immunity, emissivity, and shielding efficiency experiments.In addition, the reader is provided with the elements of electromagnetic theory and statistics required to take full advantage of the basic operational rules of reverberation chambers, including calibration proc
Electromagnetic effects involving a tokamak reactor first wall and blanket
International Nuclear Information System (INIS)
Turner, L.R.; Evans, K. Jr.; Gelbard, E.; Prater, R.
1980-01-01
Four electromagnetic effects experienced by the first wall and blanket of a tokamak reactor are considered. First, the first wall provides reduction of the growth rate of vertical axisymmetric instability and stabilization of low mode number interval kink modes. Second, if a rapid plasma disruption occurs, a current will be induced on the first wall, tending to maintain the field formerly produced by the plasma. Third, correction of plasma movement can begin on a time scale much faster than the L/R time of the first wall and blanket. Fourth, field changes, especially those from plasma disruption or from rapid discharge of a toroidal field coil, can cause substantial eddy current forces on elements of the first wall and blanket. These effects are considered specifically for the first wall and blanket of the STARFIRE commercial reactor design study
Electromagnetic processes and interactions
International Nuclear Information System (INIS)
Scheck, F.
1983-01-01
The electron and muon are important tools in testing the structure of the fundamental electromagnetic interactions. On the other hand, if these interactions are known, they serve as ideal probes for the internal structure of complex hadronic targets such as nucleons and nuclei. Purely electromagnetic interactions play a distinctive role, for obvious experimental reasons: At low and intermediate energies the effective electromagnetic coupling is larger by many orders of magnitude than the weak couplings, so that electromagnetic processes are measurable to much higher accuracy than purely weak processes. The present chapter deals primarily with applications of charged leptons to problems of nucleon and nuclear structure, and to selected precision tests of quantum electrodynamics (QED) at low momentum transfers. In most of these applications the electromagnetic interactions effectively appear in the form of external fields in the leptonic particle's Dirac equation. This is the domain where the physics of (electromagnetically) interacting leptons can still be described in the framework of an effective, though relativistic, single particle theory. (orig.)
Covariant electromagnetic field lines
Hadad, Y.; Cohen, E.; Kaminer, I.; Elitzur, A. C.
2017-08-01
Faraday introduced electric field lines as a powerful tool for understanding the electric force, and these field lines are still used today in classrooms and textbooks teaching the basics of electromagnetism within the electrostatic limit. However, despite attempts at generalizing this concept beyond the electrostatic limit, such a fully relativistic field line theory still appears to be missing. In this work, we propose such a theory and define covariant electromagnetic field lines that naturally extend electric field lines to relativistic systems and general electromagnetic fields. We derive a closed-form formula for the field lines curvature in the vicinity of a charge, and show that it is related to the world line of the charge. This demonstrates how the kinematics of a charge can be derived from the geometry of the electromagnetic field lines. Such a theory may also provide new tools in modeling and analyzing electromagnetic phenomena, and may entail new insights regarding long-standing problems such as radiation-reaction and self-force. In particular, the electromagnetic field lines curvature has the attractive property of being non-singular everywhere, thus eliminating all self-field singularities without using renormalization techniques.
Electromagnetic cellular interactions.
Cifra, Michal; Fields, Jeremy Z; Farhadi, Ashkan
2011-05-01
Chemical and electrical interaction within and between cells is well established. Just the opposite is true about cellular interactions via other physical fields. The most probable candidate for an other form of cellular interaction is the electromagnetic field. We review theories and experiments on how cells can generate and detect electromagnetic fields generally, and if the cell-generated electromagnetic field can mediate cellular interactions. We do not limit here ourselves to specialized electro-excitable cells. Rather we describe physical processes that are of a more general nature and probably present in almost every type of living cell. The spectral range included is broad; from kHz to the visible part of the electromagnetic spectrum. We show that there is a rather large number of theories on how cells can generate and detect electromagnetic fields and discuss experimental evidence on electromagnetic cellular interactions in the modern scientific literature. Although small, it is continuously accumulating. Copyright © 2010 Elsevier Ltd. All rights reserved.
Distribution functions for resonantly trapped orbits in the Galactic disc
Monari, Giacomo; Famaey, Benoit; Fouvry, Jean-Baptiste; Binney, James
2017-11-01
The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment, however, leads to singularities at resonances, which prevent quantitative comparisons with data. Here, we manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then follow the prescription of Binney, assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits depends only on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of DFs in action space.
Axisymmetric general relativistic simulations of the accretion-induced collapse of white dwarfs
International Nuclear Information System (INIS)
Abdikamalov, E. B.; Ott, C. D.; Rezzolla, L.; Dessart, L.; Dimmelmeier, H.; Marek, A.; Janka, H.-T.
2010-01-01
The accretion-induced collapse (AIC) of a white dwarf may lead to the formation of a protoneutron star and a collapse-driven supernova explosion. This process represents a path alternative to thermonuclear disruption of accreting white dwarfs in type Ia supernovae. In the AIC scenario, the supernova explosion energy is expected to be small and the resulting transient short-lived, making it hard to detect by electromagnetic means alone. Neutrino and gravitational-wave (GW) observations may provide crucial information necessary to reveal a potential AIC. Motivated by the need for systematic predictions of the GW signature of AIC, we present results from an extensive set of general-relativistic AIC simulations using a microphysical finite-temperature equation of state and an approximate treatment of deleptonization during collapse. Investigating a set of 114 progenitor models in axisymmetric rotational equilibrium, with a wide range of rotational configurations, temperatures and central densities, and resulting white dwarf masses, we extend previous Newtonian studies and find that the GW signal has a generic shape akin to what is known as a 'type III' signal in the literature. Despite this reduction to a single type of waveform, we show that the emitted GWs carry information that can be used to constrain the progenitor and the postbounce rotation. We discuss the detectability of the emitted GWs, showing that the signal-to-noise ratio for current or next-generation interferometer detectors could be high enough to detect such events in our Galaxy. Furthermore, we contrast the GW signals of AIC and rotating massive star iron core collapse and find that they can be distinguished, but only if the distance to the source is known and a detailed reconstruction of the GW time series from detector data is possible. Some of our AIC models form massive quasi-Keplerian accretion disks after bounce. The disk mass is very sensitive to progenitor mass and angular momentum
Melnikov, Vasily
2012-11-10
We derive transfer functions for an all-pass ring resonator with internal backreflection coupled to a symmetrical Fabry-Perot resonator and demonstrate electromagnetically induced transparency-like and Fano-like lineshapes tunable by backreflection in the ring resonator.
Melnikov, Vasily; Roqan, Iman S.
2012-01-01
We derive transfer functions for an all-pass ring resonator with internal backreflection coupled to a symmetrical Fabry-Perot resonator and demonstrate electromagnetically induced transparency-like and Fano-like lineshapes tunable by backreflection in the ring resonator.
Xu, Qianfan; Sandhu, Sunil; Povinelli, Michelle L; Shakya, Jagat; Fan, Shanhui; Lipson, Michal
2006-03-31
We provide the first experimental observation of structure tuning of the electromagnetically induced transparency-like spectrum in integrated on-chip optical resonator systems. The system consists of coupled silicon ring resonators with 10 microm diameter on silicon, where the coherent interference between the two coupled resonators is tuned. We measured a transparency-resonance mode with a quality factor of 11,800.
Electromagnetic drift waves dispersion for arbitrarily collisional plasmas
Energy Technology Data Exchange (ETDEWEB)
Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); Angus, J. R. [Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States)
2015-07-15
The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionless and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.
Electromagnetically induced transparency in metamaterials at near-infrared frequency
DEFF Research Database (Denmark)
Zhang, Jingjing; Xiao, Sanshui; Jeppesen, Claus
2010-01-01
We employ a planar metamaterial structure composed of a splitring-resonator (SRR) and paired nano-rods to experimentally realize a spectral response at near-infrared frequencies resembling that of electromagnetically induced transparency. A narrow transparency window associated with low loss...
The electromagnetic Brillouin precursor in one-dimensional photonic crystals
Uitham, R.; Hoenders, B. J.
2008-01-01
We have calculated the electromagnetic Brillouin precursor that arises in a one-dimensional photonic crystal that consists of two homogeneous slabs which each have a single electron resonance. This forerunner is compared with the Brillouin precursor that arises in a homogeneous double-electron
Electromagnetic fields - introduction to relevant issues
International Nuclear Information System (INIS)
Brueggemeyer, H.; Csicsaky, M.
1993-01-01
This introductory paper surveys potential sources of electric magnetic, and electro-magnetic fields. Various cases are discussed to exemplify the total frequency range: nuclear magnetic resonance tomography, high-voltage transmission lines, transformer stations, effect lighting balls, military transmitters, transmitter towers of the Postal Services and other operators, mobile radiotelephone equipment, large broadcasting transmitters, radar radiation, high-frequency heat therapy. There is evidence suggesting that electric, magnetic and electro-magnetic fields may possibly represent a certain nuisance or health hazard even at field strength occuring in equipment used for every-day-life purposes, with an emphasis on their possible actions and effects in children and adolescents. The author discusses, in conclusion, the aerial equipment ordinance issued by Lower Saxony. (Uhe) [de
Forcing scheme analysis for the axisymmetric lattice Boltzmann method under incompressible limit.
Zhang, Liangqi; Yang, Shiliang; Zeng, Zhong; Chen, Jie; Yin, Linmao; Chew, Jia Wei
2017-04-01
Because the standard lattice Boltzmann (LB) method is proposed for Cartesian Navier-Stokes (NS) equations, additional source terms are necessary in the axisymmetric LB method for representing the axisymmetric effects. Therefore, the accuracy and applicability of the axisymmetric LB models depend on the forcing schemes adopted for discretization of the source terms. In this study, three forcing schemes, namely, the trapezium rule based scheme, the direct forcing scheme, and the semi-implicit centered scheme, are analyzed theoretically by investigating their derived macroscopic equations in the diffusive scale. Particularly, the finite difference interpretation of the standard LB method is extended to the LB equations with source terms, and then the accuracy of different forcing schemes is evaluated for the axisymmetric LB method. Theoretical analysis indicates that the discrete lattice effects arising from the direct forcing scheme are part of the truncation error terms and thus would not affect the overall accuracy of the standard LB method with general force term (i.e., only the source terms in the momentum equation are considered), but lead to incorrect macroscopic equations for the axisymmetric LB models. On the other hand, the trapezium rule based scheme and the semi-implicit centered scheme both have the advantage of avoiding the discrete lattice effects and recovering the correct macroscopic equations. Numerical tests applied for validating the theoretical analysis show that both the numerical stability and the accuracy of the axisymmetric LB simulations are affected by the direct forcing scheme, which indicate that forcing schemes free of the discrete lattice effects are necessary for the axisymmetric LB method.
Computer Aided Process Planning for Non-Axisymmetric Deep Drawing Products
Park, Dong Hwan; Yarlagadda, Prasad K. D. V.
2004-06-01
In general, deep drawing products have various cross-section shapes such as cylindrical, rectangular and non-axisymmetric shapes. The application of the surface area calculation to non-axisymmetric deep drawing process has not been published yet. In this research, a surface area calculation for non-axisymmetric deep drawing products with elliptical shape was constructed for a design of blank shape of deep drawing products by using an AutoLISP function of AutoCAD software. A computer-aided process planning (CAPP) system for rotationally symmetric deep drawing products has been developed. However, the application of the system to non-axisymmetric components has not been reported yet. Thus, the CAPP system for non-axisymmetric deep drawing products with elliptical shape was constructed by using process sequence design. The system developed in this work consists of four modules. The first is recognition of shape module to recognize non-axisymmetric products. The second is a three-dimensional (3-D) modeling module to calculate the surface area for non-axisymmetric products. The third is a blank design module to create an oval-shaped blank with the identical surface area. The forth is a process planning module based on the production rules that play the best important role in an expert system for manufacturing. The production rules are generated and upgraded by interviewing field engineers. Especially, the drawing coefficient, the punch and die radii for elliptical shape products are considered as main design parameters. The suitability of this system was verified by applying to a real deep drawing product. This CAPP system constructed would be very useful to reduce lead-time for manufacturing and improve an accuracy of products.
Reynolds number and geometry effects in laminar axisymmetric isothermal counterflows
Scribano, Gianfranco
2016-12-29
The counterflow configuration is a canonical stagnation flow, featuring two opposed impinging round jets and a mixing layer across the stagnation plane. Although counterflows are used extensively in the study of reactive mixtures and other applications where mixing of two streams is required, quantitative data on the scaling properties of the flow field are lacking. The aim of this work is to characterize the velocity and mixing fields in isothermal counterflows over a wide range of conditions. The study features both experimental data from particle image velocimetry and results from detailed axisymmetric simulations. The scaling laws for the nondimensional velocity and mixture fraction are obtained as a function of an appropriate Reynolds number and the ratio of the separation distance of the nozzles to their diameter. In the range of flow configurations investigated, the nondimensional fields are found to depend primarily on the separation ratio and, to a lesser extent, the Reynolds number. The marked dependence of the velocity field with respect to the separation ratio is linked to a high pressure region at the stagnation point. On the other hand, Reynolds number effects highlight the role played by the wall boundary layer on the interior of the nozzles, which becomes less important as the separation ratio decreases. The normalized strain rate and scalar dissipation rate at the stagnation plane are found to attain limiting values only for high values of the Reynolds number. These asymptotic values depend markedly on the separation ratio and differ significantly from the values produced by analytical models. The scaling of the mixing field does not show a limiting behavior as the separation ratio decreases to the smallest practical value considered.
Axisymmetric Numerical Modeling of Pulse Detonation Rocket Engines
Morris, Christopher I.
2005-01-01
Pulse detonation rocket engines (PDREs) have generated research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional rocket engines. The detonative mode of combustion employed by these devices offers a thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional rocket engines and gas turbines. However, while this theoretical advantage has spurred considerable interest in building PDRE devices, the unsteady blowdown process intrinsic to the PDRE has made realistic estimates of the actual propulsive performance problematic. The recent review article by Kailasanath highlights some of the progress that has been made in comparing the available experimental measurements with analytical and numerical models. In recent work by the author, a quasi-one-dimensional, finite rate chemistry CFD model was utilized to study the gasdynamics and performance characteristics of PDREs over a range of blowdown pressure ratios from 1-1000. Models of this type are computationally inexpensive, and enable first-order parametric studies of the effect of several nozzle and extension geometries on PDRE performance over a wide range of conditions. However, the quasi-one-dimensional approach is limited in that it cannot properly capture the multidimensional blast wave and flow expansion downstream of the PDRE, nor can it resolve nozzle flow separation if present. Moreover, the previous work was limited to single-pulse calculations. In this paper, an axisymmetric finite rate chemistry model is described and utilized to study these issues in greater detail. Example Mach number contour plots showing the multidimensional blast wave and nozzle exhaust plume are shown. The performance results are compared with the quasi-one-dimensional results from the previous paper. Both Euler and Navier-Stokes solutions are calculated in order to determine the effect of viscous
Electromagnetic behaviour of the earth and planets
International Nuclear Information System (INIS)
McCarthy, A.J.
2002-01-01
Forecast problems of global warming, rising sea-levels, UV enhancement, and solar disruptions of power grids and satellite communications, have been widely discussed. Added to these calamities is the steady decay of the Earth's magnetic radiation shield against high energy particles. A system of solar-induced aperiodic electromagnetic resonances, referred to here as the Debye resonances, is resurrected as the preferred basis for describing the electromagnetic behaviour of the Earth and planets. Debye's two basic solutions to the spherical vector wave equation provide foundations for electromagnetic modes of the terrestrial and gaseous planets respectively in contrast with the separate electric and magnetic approaches usually taken. For those engaged in radiation protection issues, this paper provides the first published account of how the Sun apparently triggers an Earth magnetic shield against its own harmful radiation. Disturbances from the Sun - which are random in terms of polarity, polarisation, amplitude, and occurrence - are considered here to trigger the Debye modes and generate observed planetary electric and magnetic fields. Snapping or reconnection of solar or interplanetary field lines, acting together with the newly conceived magnetospheric transmission lines of recent literature, is suspected as the excitation mechanism. Virtual replacement of free space by plasma, places the electromagnetic behaviour of the Earth and planets under greatly enhanced control from the Sun. From a radiation protection viewpoint, modal theory based on solar-terrestrial coupling provides a new insight into the origin of the Earth's magnetic radiation shield, greater understanding of which is essential to development of global cosmic radiation protection strategies. Should man-made influences unduly increase conductivities of the Earth's magnetosphere, planet Earth could be left with no magnetic radiation shield whatsoever. Copyright (2002) Australasian Radiation Protection
Electromagnetic fields and their impacts
Prša, M. A.; Kasaš-Lažetić, K. K.
2018-01-01
The main goal of this paper is to briefly recall some different electromagnetic field definitions, some macroscopic sources of electromagnetic fields, electromagnetic fields classification regarding time dependences, and the ways of field determination in concrete cases. After that, all the mechanisms of interaction between electromagnetic field and substance, on atomic level, are described in details. Interaction between substance and electric field is investigated separately from the substance and magnetic field interaction. It is demonstrated that, in all cases of the unique electromagnetic field, total interaction can be treated as a superposition of two separated interactions. Finally, the main electromagnetic fields surrounding us is cited and discussed.
Directory of Open Access Journals (Sweden)
Fan Yuanyuan
2016-11-01
Full Text Available This paper describes mathematical models of an electromagnetic and piezoelectric hybrid energy harvesting system and provides an analysis of the relationship between the resonance frequency and the configuration parameters of the system. An electromagnetic and piezoelectric energy harvesting device was designed and the experimental results showed good agreement with the analytical results. The maximum load power of the hybrid energy harvesting system achieved 4.25 mW at a resonant frequency of 18 Hz when the acceleration was 0.7 g, which is an increase of 15% compared with the 3.62 mW achieved by a single electromagnetic technique.
Gravitation and electromagnetism
Apsel, D
1979-01-01
Through an examination of the Bohm-Aharonov experiment, a new theory of gravitation and electromagnetism is proposed. The fundamental assumption of the theory is that the motion of a particle in a combination of gravitational and electromagnetic fields is determined from a variational principle of the form delta integral /sub A//sup B /d tau =0. The form of the physical time is determined from an examination of the Maxwell-Einstein action function. The field and motion equations are formally identical to those of Maxwell-Einstein theory. The theory predicts that even in a field-free region of space, electromagnetic potentials can alter the phase of a wave function and the lifetime of a charged particle. The phase alteration has been observed in the Bohm-Aharonov experiment. There is an indication that the lifetime alteration has shown up in a recent CERN storage ring experiment. Experimental tests are proposed. (11 refs).
Applied electromagnetic scattering theory
Osipov, Andrey A
2017-01-01
Besides classical applications (radar and stealth, antennas, microwave engineering), scattering and diffraction are enabling phenomena for some emerging research fields (artificial electromagnetic materials or metamaterials, terahertz technologies, electromagnetic aspects of nano-science). This book is a tutorial for advanced students who need to study diffraction theory. The textbook gives fundamental knowledge about scattering and diffraction of electromagnetic waves and provides some working examples of solutions for practical high-frequency scattering and diffraction problems. The book focuses on the most important diffraction effects and mechanisms influencing the scattering process and describes efficient and physically justified simulation methods - physical optics (PO) and the physical theory of diffraction (PTD) - applicable in typical remote sensing scenarios. The material is presented in a comprehensible and logical form, which relates the presented results to the basic principles of electromag...
Metamaterial electromagnetic wave absorbers.
Watts, Claire M; Liu, Xianliang; Padilla, Willie J
2012-06-19
The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Instabilities in electromagnetic quasilevitation.
Spragg, Kirk; Letout, Sebastien; Ernst, R; Sneyd, Alfred; Fautrelle, Yves
2014-05-01
We investigate free-surface instabilities occurring in various industrial processes involving liquid metal. Of particular interest is the behavior of the free surface of a pool of liquid metal when it is submitted to an alternating magnetic field. Experimentally, we study the effect of a vertical alternating medium-frequency magnetic field on an initially circular pool. We observe various types of behavior according to magnetic field amplitude, e.g., axisymmetric deformations, azimuthal mode structures, slow radial oscillation of the pool perimeter, and random rotation of the pool around its center. Drop rotation could be attributed to nonsymmetric shape deformations. The effect of oxidation leads to drastic changes in pool behavior. The experimental results are then compared to a linear stability analysis of the free surface of a circular liquid drop.
A variational principle for the axisymmetric stability of rotating relativistic stars
International Nuclear Information System (INIS)
Prabhu, Kartik; Wald, Robert M; Schiffrin, Joshua S
2016-01-01
It is well known that all rotating perfect fluid stars in general relativity are unstable to certain non-axisymmetric perturbations via the Chandrasekhar–Friedman–Schutz (CFS) instability. However, the mechanism of the CFS instability requires, in an essential way, the loss of angular momentum by gravitational radiation and, in many instances, it acts on too long a timescale to be physically/astrophysically relevant. It is therefore of interest to examine the stability of rotating, relativistic stars to axisymmetric perturbations, where the CFS instability does not occur. In this paper, we provide a Rayleigh–Ritz-type variational principle for testing the stability of perfect fluid stars to axisymmetric perturbations, which generalizes to axisymmetric perturbations of rotating stars a variational principle given by Chandrasekhar for spherical perturbations of static, spherical stars. Our variational principle provides a lower bound to the rate of exponential growth in the case of instability. The derivation closely parallels the derivation of a recently obtained variational principle for analyzing the axisymmetric stability of black holes. (paper)
Tunable Magnetic Resonance in Microwave Spintronics Devices
Chen, Yunpeng; Fan, Xin; Xie, Yunsong; Zhou, Yang; Wang, Tao; Wilson, Jeffrey D.; Simons, Rainee N.; Chui, Sui-Tat; Xiao, John Q.
2015-01-01
Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe based tunable microwave spintronics devices, which is 10X higher than conventional methods.
The theory of electromagnetism
Jones, D S
1964-01-01
The Theory of the Electomagnetism covers the behavior of electromagnetic fields and those parts of applied mathematics necessary to discover this behavior. This book is composed of 11 chapters that emphasize the Maxwell's equations. The first chapter is concerned with the general properties of solutions of Maxwell's equations in matter, which has certain macroscopic properties. The succeeding chapters consider specific problems in electromagnetism, including the determination of the field produced by a variable charge, first in isolation and then in the surface distributions of an antenna. The
Das, Ashok
2013-01-01
These lecture notes on electromagnetism have evolved from graduate and undergraduate EM theory courses given by the author at the University of Rochester, with the basics presented with clarity and his characteristic attention to detail. The thirteen chapters cover, in logical sequence, topics ranging from electrostatics, magnetostatics and Maxwell's equations to plasmas and radiation. Boundary value problems are treated extensively, as are wave guides, electromagnetic interactions and fields. This second edition comprises many of the topics expanded with more details on the derivation of vari
Electromagnetic clutches and couplings
Vorob'Yeva, T M; Fry, D W; Higinbotham, W
2013-01-01
Electromagnetic Clutches and Couplings contains a detailed description of U.S.S.R. electromagnetic friction clutches, magnetic couplings, and magnetic particle couplings. This book is divided into four chapters. The first chapter discusses the design and construction of magnetic (solenoid-operated) couplings, which are very quick-acting devices and used in low power high-speed servo-systems. Chapter 2 describes the possible fields of application, design, construction, and utilization of magnetic particle couplings. The aspects of construction, design, and utilization of induction clutches (sli
Improved Electromagnetic Brake
Martin, Toby B.
2004-01-01
A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may
Essentials of Computational Electromagnetics
Sheng, Xin-Qing
2012-01-01
Essentials of Computational Electromagnetics provides an in-depth introduction of the three main full-wave numerical methods in computational electromagnetics (CEM); namely, the method of moment (MoM), the finite element method (FEM), and the finite-difference time-domain (FDTD) method. Numerous monographs can be found addressing one of the above three methods. However, few give a broad general overview of essentials embodied in these methods, or were published too early to include recent advances. Furthermore, many existing monographs only present the final numerical results without specifyin
Resonance – Journal of Science Education | Indian Academy of ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 8. Science Academies' Refresher Course on Classical Mechanics and Electromagnetism. Information and Announcements Volume 19 Issue 8 August 2014 pp 775-775 ...
On electromagnetic forming processes in finitely strained solids: Theory and examples
Thomas, J. D.; Triantafyllidis, N.
2009-08-01
The process of electromagnetic forming (EMF) is a high velocity manufacturing technique that uses electromagnetic (Lorentz) body forces to shape sheet metal parts. EMF holds several advantages over conventional forming techniques: speed, repeatability, one-sided tooling, and most importantly considerable ductility increase in several metals. Current modeling techniques for EMF processes are not based on coupled variational principles to simultaneously account for electromagnetic and mechanical effects. Typically, separate solutions to the electromagnetic (Maxwell) and motion (Newton) equations are combined in staggered or lock-step methods, sequentially solving the mechanical and electromagnetic problems. The present work addresses these issues by introducing a fully coupled Lagrangian (reference configuration) least-action variational principle, involving magnetic flux and electric potentials and the displacement field as independent variables. The corresponding Euler-Lagrange equations are Maxwell's and Newton's equations in the reference configuration, which are shown to coincide with their current configuration counterparts obtained independently by a direct approach. The general theory is subsequently simplified for EMF processes by considering the eddy current approximation. Next, an application is presented for axisymmetric EMF problems. It is shown that the proposed variational principle forms the basis of a variational integration numerical scheme that provides an efficient staggered solution algorithm. As an illustration a number of such processes are simulated, inspired by recent experiments of freely expanding uncoated and polyurea-coated aluminum tubes.
Optical phased array using guided resonance with backside reflectors
Energy Technology Data Exchange (ETDEWEB)
Horie, Yu; Arbabi, Amir; Faraon, Andrei
2018-03-13
Methods and systems for controlling the phase of electromagnetic waves are disclosed. A device can consist of a guided resonance grating layer, a spacer, and a reflector. A plurality of devices, arranged in a grid pattern, can control the phase of reflected electromagnetic phase, through refractive index control. Carrier injection, temperature control, and optical beams can be applied to control the refractive index.
New perspectives on classical electromagnetism
Cote, Paul J.
2009-01-01
The fallacies associated with the gauge concept in electromagnetism are illustrated. A clearer and more valid formulation of the basics of classical electromagnetism is provided by recognizing existing physical constraints as well as the physical reality of the vector potential.
Electromagnetic fields in stratified media
Li, Kai
2009-01-01
Dealing with an important branch of electromagnetic theory with many useful applications in subsurface communication, radar, and geophysical prospecting and diagnostics, this book introduces electromagnetic theory and wave propagation in complex media.
Electromagnetic interference: a radiant future!
Leferink, Frank Bernardus Johannes
2015-01-01
Although Electromagnetic Interference and Electromagnetic Compatibility are well established domains, the introduction of new technologies results in new challenges. Changes in both measurement techniques, and technological trends resulting in new types of interference are described. These are the
Buffer-gas-induced absorption resonances in Rb vapor
International Nuclear Information System (INIS)
Mikhailov, Eugeniy E.; Novikova, Irina; Rostovtsev, Yuri V.; Welch, George R.
2004-01-01
We observe transformation of the electromagnetically induced transparency (EIT) resonance into an absorption resonance in a Λ interaction configuration in a cell filled with 87 Rb and a buffer gas. This transformation occurs as one-photon detuning of the coupling fields is varied from the atomic transition. No such absorption resonance is found in the absence of a buffer gas. The width of the absorption resonance is several times smaller than the width of the EIT resonance, and the changes of absorption near these resonances are about the same. Similar absorption resonances are detected in the Hanle configuration in a buffered cell
Electromagnetic and nuclear radiation detector using micromechanical sensors
Thundat, Thomas G.; Warmack, Robert J.; Wachter, Eric A.
2000-01-01
Electromagnetic and nuclear radiation is detected by micromechanical sensors that can be coated with various interactive materials. As the micromechanical sensors absorb radiation, the sensors bend and/or undergo a shift in resonance characteristics. The bending and resonance changes are detected with high sensitivity by any of several detection methods including optical, capacitive, and piezoresistive methods. Wide bands of the electromagnetic spectrum can be imaged with picoJoule sensitivity, and specific absorptive coatings can be used for selective sensitivity in specific wavelength bands. Microcantilevers coated with optical cross-linking polymers are useful as integrating optical radiation dosimeters. Nuclear radiation dosimetry is possible by fabricating cantilevers from materials that are sensitive to various nuclear particles or radiation. Upon exposure to radiation, the cantilever bends due to stress and its resonance frequency shifts due to changes in elastic properties, based on cantilever shape and properties of the coating.
Electromagnetic excitation of 136Xe in relativistic heavy ion collisions
International Nuclear Information System (INIS)
Schmidt, R.D.
1991-11-01
In the framework of the experimental program at the accelerator facilities SIS/ESR at the Society for Heavy Ion Research in Darmstadt a detector system for relativistic neutrons was developed, constructed, and applied in first experiments. An essential research aim is the study of collective states after electromagnetic excitation in relativistic heavy ion collisions. In peripheral collisions high-energy virtual photons are exchanged. This leads to the excitation of giant resonances, especially of the giant dipole and quadrupole resonance. An essential decay channel of giant resonances in heavy nuclei is the emission of neutrons, followed by the emission of γ radiation below the particle threshold. These decay channels were studied with the detector system developed by the LAND collaboration. A first experiment on the electromagnetic excitation was performed with a 136 Xe beam at an energy of 700 MeV/u and Pb respectively C targets. (orig./HSI) [de
Static harmonization of dynamically harmonized Fourier transform ion cyclotron resonance cell.
Zhdanova, Ekaterina; Kostyukevich, Yury; Nikolaev, Eugene
2017-08-01
Static harmonization in the Fourier transform ion cyclotron resonance cell improves the resolving power of the cell and prevents dephasing of the ion cloud in the case of any trajectory of the charged particle, not necessarily axisymmetric cyclotron (as opposed to dynamic harmonization). We reveal that the Fourier transform ion cyclotron resonance cell with dynamic harmonization (paracell) is proved to be statically harmonized. The volume of the statically harmonized potential distribution increases with an increase in the number of trap segments.
Hybrid localized waves supported by resonant anisotropic metasurfaces
DEFF Research Database (Denmark)
Bogdanov, A. A.; Yermakov, O. Y.; Ovcharenko, A. I.
2016-01-01
We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime.......We study both theoretically and experimentally a new class of surface electromagnetic waves supported by resonant anisotropic metasurface. At certain frequency this type of metasurface demonstrates the topological transition from elliptical to hyperbolic regime....
Trapped resonance modes at tapered SR masks in a beam pipe
International Nuclear Information System (INIS)
Sakanaka, Shogo.
1995-04-01
We report on the possibility that electromagnetic resonances arise at a certain configuration of SR (synchrotron radiation) masks installed in a beam pipe. Because such resonances can cause coupled-bunch instabilities, care should be taken to avoid a resonance structure or to damp the Q-values of the resonances. (author)
Nemeth, Michael P.; Schultz, Marc R.
2012-01-01
A detailed exact solution is presented for laminated-composite circular cylinders with general wall construction and that undergo axisymmetric deformations. The overall solution is formulated in a general, systematic way and is based on the solution of a single fourth-order, nonhomogeneous ordinary differential equation with constant coefficients in which the radial displacement is the dependent variable. Moreover, the effects of general anisotropy are included and positive-definiteness of the strain energy is used to define uniquely the form of the basis functions spanning the solution space of the ordinary differential equation. Loading conditions are considered that include axisymmetric edge loads, surface tractions, and temperature fields. Likewise, all possible axisymmetric boundary conditions are considered. Results are presented for five examples that demonstrate a wide range of behavior for specially orthotropic and fully anisotropic cylinders.
Low frequency electromagnetic field sensor
International Nuclear Information System (INIS)
Zhu Min; Zhou Yan; He Yicheng; Zheng Zhenxing; Liu Sunkun
2000-01-01
The measurement technique of low frequency electromagnetic field is reported. According to this principle, the authors have designed a sensor, which is used to measure the natural electromagnetic field, SLEMP and electromagnetic signals generated by some explosions. The frequency band of this sensor is from 0.08 Hz to 2 MHz
Electromagnetic radiation detector
Benson, Jay L.; Hansen, Gordon J.
1976-01-01
An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.
Disconnected electromagnetic form factors
International Nuclear Information System (INIS)
Wilcox, Walter
2001-01-01
Preliminary results of a calculation of disconnected nucleon electromagnetic factors factors on the lattice are presented. The implementation of the numerical subtraction scheme is outlined. A comparison of results for electric and magnetic disconnected form factors on two lattice sizes with those of the Kentucky group is presented. Unlike previous results, the results found in this calculation are consistent with zero in these sectors
Electromagnetic distance measurement
1967-01-01
This book brings together the work of forty-eight geodesists from twenty-five countries. They discuss various new electromagnetic distance measurement (EDM) instruments - among them the Tellurometer, Geodimeter, and air- and satellite-borne systems - and investigate the complex sources of error.
Equivalence principles and electromagnetism
Ni, W.-T.
1977-01-01
The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.
Electromagnetic Environments Simulator (EMES)
International Nuclear Information System (INIS)
Varnado, G.B.
1975-11-01
A multipurpose electromagnetic environments simulator has been designed to provide a capability for performing EMR, EMP, and lightning near stroke testing of systems, subsystems and components in a single facility. This report describes the final facility design and presents the analytical and experimental verification of the design
Pregnancy and electromagnetic fields
International Nuclear Information System (INIS)
Bisseriex, Ch.; Laurent, P.; Cabaret, Ph.; Bonnet, C.; Marteau, E.; Le Berre, G.; Tirlemont, S.; Castro, H.; Becker, A.; Demaret, Ph.; Donati, M.; Ganem, Y.; Moureaux, P.
2011-07-01
This document briefly indicates the status of knowledge regarding the effect of magnetic fields on biological tissues and pregnancy, outlines the lack of data on some frequencies and the weakness of studies on long term effects on child development. It evokes the issue of exposure assessment and that of identification of workstations exposed to electromagnetic fields
Electromagnetic structure of nuclei
International Nuclear Information System (INIS)
Arnold, R.G.
1986-07-01
A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei, including nucleon form factors from both quantum chromodynamics and electron scattering data, measurements of the deuteron and triton form factors, quasi-elastic scattering, and the EMC effect. 47 refs., 13 figs
"Hearing" Electromagnetic Waves
Rojo, Marta; Munoz, Juan
2014-01-01
In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…
Non-axisymmetric line-driven disc winds - I. Disc perturbations
Dyda, Sergei; Proga, Daniel
2018-04-01
We study mass outflows driven from accretion discs by radiation pressure due to spectral lines. To investigate non-axisymmetric effects, we use the ATHENA++ code and develop a new module to account for radiation pressure driving. In 2D, our new simulations are consistent with previous 2D axisymmetric solutions by Proga et al., who used the ZEUS 2D code. Specifically, we find that the disc winds are time dependent, characterized by a dense stream confined to ˜45° relative to the disc mid-plane and bounded on the polar side by a less dense, fast stream. In 3D, we introduce a vertical, ϕ-dependent, subsonic velocity perturbation in the disc mid-plane. The perturbation does not change the overall character of the solution but global outflow properties such as the mass, momentum, and kinetic energy fluxes are altered by up to 100 per cent. Non-axisymmetric density structures develop and persist mainly at the base of the wind. They are relatively small, and their densities can be a few times higher than the azimuthal average. The structure of the non-axisymmetric and axisymmetric solutions differ also in other ways. Perhaps most importantly from the observational point of view are the differences in the so-called clumping factors, that serve as a proxy for emissivity due to two body processes. In particular, the spatially averaged clumping factor over the entire fast stream, while it is of a comparable value in both solutions, it varies about 10 times faster in the non-axisymmetric case.
Gauge theory of weak, electromagnetic and dual electromagnetic interactions
International Nuclear Information System (INIS)
Soln, J.
1980-01-01
An SU 2 x U 1 algebra, in addition to the ordinary electric charge, also establishes the existence of the dual electric charge. This is taken as an indication of the existence of dual electromagnetic interactions in nature. Here, the unification of weak, electromagnetic and dual electromagnetic interactions is performed. The Yang-Mills-type group which contains the electromagnetic, dual electromagnetic and weak currents is SUsub(L,2) x U 1 x U' 1 . The masses of vector mesons are generated through the Higgs-Kibble mechanism. A simple consistency requirement suggests that dual electromagnetism and ordinary electromagnetism have the same strengths, leading the theory to a rather good agreement with experiments. (author)
Electromagnetic decay of two-phonon states
International Nuclear Information System (INIS)
Catara, F.; Chomaz, Ph.; Van Giai, N.; Paris-11 Univ., 91 - Orsay
1991-01-01
The electromagnetic decay of two-phonon states corresponding to the multi-excitation of giant resonances is studied. The calculations are performed within a boson expansion approach and the elementary modes are constructed in random phase approximation (RPA). The rates for direct transition of two-phonon states to the ground state turn out to be not negligibly smaller than those from the (single) giant resonances. The former transitions are accompanied by a γ-ray whose energy is equal to the sum of the two phonon energies. Thus the detection of such high energy γ-rays could provide a signature of the excitation of two-phonon states. (author) 9 refs., 3 tabs
Experimental studies on an axisymmetric divertor in DIVA(JFT-2a)
International Nuclear Information System (INIS)
Yamamoto, Shin
1979-03-01
DIVA(JFT-2a) is the first tokamak with an axisymmetric divertor in the world. Objectives of the experiments were i) Plasma production and confinement in a tokamak with a separatrix magnetic surface, and ii) divertor effects on radiation loss and plasma confinement. The results so far are as follows: i) The equilibrium with a separatrix magnetic surface is stable during the discharge. ii) There is an ergodic region near the separatrix magnetic surface due to non-axisymmetric magnetic perturbations. iii) The divertor reduces radiation loss and increases energy confinement time. iv) The divertor does not affect the transport process in the main plasma. (author)
ASCOT-1, Thermohydraulics of Axisymmetric PWR Core with Homogeneous Flow During LOCA
International Nuclear Information System (INIS)
1978-01-01
1 - Nature of the physical problem solved: ASCOT-1 is used to analyze the thermo-hydraulic behaviour in a PWR core during a loss-of-coolant accident. 2 - Method of solution: The core is assumed to be axisymmetric two-dimensional and the conservation laws are solved by the method of characteristics. For the temperature response of fuel in the annular regions into which the core is divided, the heat conduction equations are solved by an explicit method with averaged flow conditions. 3 - Restrictions on the complexity of the problem: Axisymmetric two-dimensional homogeneous flows
Asymptotic properties of axisymmetric Stokes flow of a viscous liquid with intersecting boundaries
International Nuclear Information System (INIS)
Voinov, O.V.
2004-01-01
The general axisymmetric problem on the liquid flow by the low Reynolds number when the boundary surfaces (both of the solid body and free one) are intersecting at the certain angle on the moving line, is considered. The work is aimed at establishing the asymptotic regularities of the behavior of the current function and voltages in the small vicinity of the intersection (contact) line of the boundary surfaces. The asymptotic analysis makes it possible to consider the arbitrary axisymmetric Stokes flow with the intersecting boundaries [ru
Stable operation of an effectively axisymmetric neutral beam driven tandem mirror
International Nuclear Information System (INIS)
Molvik, A.W.; Barter, J.D.; Buchenauer, D.A.; Casper, T.A.; Correll, D.L.; Dimonte, G.; Falabella, S.; Foote, J.H.; Pincosy, P.A.
1990-01-01
A quiescent plasma is sustained for 80 energy confinement times by only gas fuelling and neutral beam heating in an axisymmetric region of the Tandem Mirror Experiment Upgrade (TMX-U). This plasma should be unstable because of the bad magnetic curvature and the absence of ion cyclotron heating which previously provided ponderomotive stabilization to sustain plasmas in bad-curvature regions of other axisymmetric mirror experiments. The TMX-U data are consistent with stabilization by a symbiosis between two mechanisms - line tying, which reduces the growth rate, and finite Larmor radius edge stabilization, which can result in quiescent operation. (author). 42 refs, 8 figs, 1 tab
Numerical Investigation of Pressure Losses in Axisymmetric Sudden Expansion with a Chamfer
Energy Technology Data Exchange (ETDEWEB)
Bae, Youngmin; Kim, Youngin; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-05-15
In this paper, the pressure losses through axisymmetric sudden expansions with a chamfer are analyzed by means of numerical simulation, with an emphasis on the effect of the Reynolds number. In this study, we investigate numerically the turbulent flow in axisymmetric sudden expansions having a slight chamfer on the edge. With the aim of investigating the impact of Reynolds number on the expansion losses in a time-averaged sense, an extensive set of simulations is carried out. On the basis of numerical results, we also propose a general correlation to estimate the local loss coefficient in sudden expansions with a chamfer.
Numerical Investigation of Pressure Losses in Axisymmetric Sudden Expansion with a Chamfer
International Nuclear Information System (INIS)
Bae, Youngmin; Kim, Youngin; Kim, Keung Koo
2014-01-01
In this paper, the pressure losses through axisymmetric sudden expansions with a chamfer are analyzed by means of numerical simulation, with an emphasis on the effect of the Reynolds number. In this study, we investigate numerically the turbulent flow in axisymmetric sudden expansions having a slight chamfer on the edge. With the aim of investigating the impact of Reynolds number on the expansion losses in a time-averaged sense, an extensive set of simulations is carried out. On the basis of numerical results, we also propose a general correlation to estimate the local loss coefficient in sudden expansions with a chamfer
Compact formulas for bounce/transit averaging in axisymmetric tokamak geometry
Energy Technology Data Exchange (ETDEWEB)
Duthoit, F.-X. [SNU Division of Graduate Education for Sustainabilization of Foundation Energy, Seoul National University, Seoul 151-742 (Korea, Republic of); Brizard, A. J. [Department of Physics, Saint Michael' s College, Colchester, Vermont 05439 (United States); Hahm, T. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)
2014-12-15
Compact formulas for bounce and transit orbit averaging of the fluctuation-amplitude eikonal factor in axisymmetric tokamak geometry, which is frequently encountered in bounce-gyrokinetic description of microturbulence, are given in terms of the Jacobi elliptic functions and elliptic integrals. These formulas are readily applicable to the calculation of the neoclassical susceptibility in the framework of modern bounce-gyrokinetic theory. In the long-wavelength limit for axisymmetric electrostatic perturbations, we recover the expression for the Rosenbluth-Hinton residual zonal flow [M. N. Rosenbluth and F. L. Hinton, Phys. Rev. Lett. 80, 724 (1998)] accurately.
Axisymmetric Synthetic Jet Actuators with Large Streamwise Dimensions
Czech Academy of Sciences Publication Activity Database
Kordík, Jozef; Trávníček, Zdeněk
2013-01-01
Roč. 51, č. 12 (2013), s. 2862-2877 ISSN 0001-1452 R&D Projects: GA ČR GPP101/12/P556; GA ČR(CZ) GCP101/11/J019 Institutional support: RVO:61388998 Keywords : synthetic jet * synthetic jet actuator * resonance frequency Subject RIV: BK - Fluid Dynamics Impact factor: 1.165, year: 2013 http://arc.aiaa.org/doi/abs/10.2514/1.J052504
Wave propagation in electromagnetic media
International Nuclear Information System (INIS)
Davis, J.L.
1990-01-01
This book is concerned with wave propagation in reacting media, specifically in electromagnetic materials. An account is presented of the mathematical methods of wave phenomena in electromagnetic materials. The author presents the theory of time-varying electromagnetic fields, which involves a discussion of Faraday's laws, Maxwell's equations and their application to electromagnetic wave propagation under a variety of conditions. The author gives a discussion of magnetohydrodynamics and plasma physics. Chapters are included on quantum mechanics and the theory of relativity. The mathematical foundation of electromagnetic waves vis a vis partial differential equations is discussed
Electromagnetic-radiation absorption by water
Lunkenheimer, P.; Emmert, S.; Gulich, R.; Köhler, M.; Wolf, M.; Schwab, M.; Loidl, A.
2017-12-01
Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.
Electromagnetic-radiation absorption by water.
Lunkenheimer, P; Emmert, S; Gulich, R; Köhler, M; Wolf, M; Schwab, M; Loidl, A
2017-12-01
Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis. By combining dielectric, microwave, THz, and far-infrared spectroscopy, here we provide nearly continuous temperature-dependent broadband spectra of water. Moreover, we find that corresponding spectra for aqueous solutions reveal the same features as pure water. However, in contrast to the latter, crystallization in these solutions can be avoided by supercooling. As different spectral contributions tend to disentangle at low temperatures, this enables us to deconvolute them when approaching the glass transition under cooling. We find that the overall spectral development, including the 20 GHz feature (employed for microwave heating), closely resembles the behavior known for common supercooled liquids. Thus water's absorption of electromagnetic waves at room temperature is not unusual but very similar to that of glass-forming liquids at elevated temperatures, deep in the low-viscosity liquid regime, and should be interpreted along similar lines.
International Nuclear Information System (INIS)
Fuchs, J; Duffy, G J; Rowlands, W J; Lezama, A; Hannaford, P; Akulshin, A M
2007-01-01
We present an experimental study of sub-natural width resonances in fluorescence from a collimated beam of 6 Li atoms excited on the D 1 and D 2 lines by a bichromatic laser field. We show that in addition to ground-state Zeeman coherence, coherent population oscillations between ground and excited states contribute to the sub-natural resonances. High-contrast resonances of electromagnetically induced transparency and electromagnetically induced absorption due to both effects, i.e., ground-state Zeeman coherence and coherent population oscillations, are observed
Detailed observations of the source of terrestrial narrowband electromagnetic radiation
Kurth, W. S.
1982-01-01
Detailed observations are presented of a region near the terrestrial plasmapause where narrowband electromagnetic radiation (previously called escaping nonthermal continuum radiation) is being generated. These observations show a direct correspondence between the narrowband radio emissions and electron cyclotron harmonic waves near the upper hybrid resonance frequency. In addition, electromagnetic radiation propagating in the Z-mode is observed in the source region which provides an extremely accurate determination of the electron plasma frequency and, hence, density profile of the source region. The data strongly suggest that electrostatic waves and not Cerenkov radiation are the source of the banded radio emissions and define the coupling which must be described by any viable theory.
Electromagnetically induced transparency in an open multilevel system
International Nuclear Information System (INIS)
Li Tian; Lu Meiju; Weinstein, Jonathan D.
2011-01-01
Electromagnetically induced transparency in a multilevel system is investigated in 173 Yb. The level structure investigated is ''open'' in that the light that gives rise to the transparency also resonantly couples the atoms to excited states which do not exhibit electromagnetically induced transparency. The resulting reduction of transparency is investigated experimentally and theoretically. It is found that, while the transparency is poor in certain regimes, it can be made to perform arbitrarily well in the limit of a large intensity imbalance between the optical fields.