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Sample records for electromagnetic cascades produced

  1. Hadron cascades produced by electromagnetic cascades

    SciTech Connect

    Nelson, W.R.; Jenkins, T.M.; Ranft, J.

    1986-12-01

    A method for calculating high energy hadron cascades induced by multi-GeV electron and photon beams is described. Using the EGS4 computer program, high energy photons in the EM shower are allowed to interact hadronically according to the vector meson dominance (VMD) model, facilitated by a Monte Carlo version of the dual multistring fragmentation model which is used in the hadron cascade code FLUKA. The results of this calculation compare very favorably with experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets (i.e., yields in secondary particle beam lines). Electron beam induced hadron star density contours are also presented and are compared with those produced by proton beams. This FLUKA-EGS4 coupling technique could find use in the design of secondary beams, in the determination high energy hadron source terms for shielding purposes, and in the estimation of induced radioactivity in targets, collimators and beam dumps.

  2. Nuclear cascades in electromagnetic showers produced by primary gamma-quanta in the atmosphere

    NASA Technical Reports Server (NTRS)

    Danilova, T. V.; Erlykin, A. D.; Mironov, A. V.; Tukish, E. I.

    1985-01-01

    Distributions were calculated for the number of electrons N sub e, number of muons with the energy above 5 GeV N sub mu and the energy of hadron component E sub h in electromagnetic showers, produced by primary gamma-quanta with energies theta approx. equals 30 deg and observed at the mountain level 700 g/square centimeters. The mean number of nuclear interactions of photos with the energy above 5 GeV is about 0.3 per each TeV of the primary energy and nuclear cascades take out in average about 2% of the total shower energy. The mean number of 5 GeV muons for the electromagnetic shower is (2 to 5)% from the number of muons in cosmic ray showers with the same number of electrons at the observation level. similar value for the total energy of hadron component is also (2 to 5)%. N sub mu and N sub e values as well as E sub h and n sub e don't correlate at the fixed primary energy E sug gamma (o). Between N sub mu and E sub h there is a positive correlation at the given E sub gamma.

  3. Analytical model for electromagnetic cascades in rotating electric field

    SciTech Connect

    Nerush, E. N.; Bashmakov, V. F.; Kostyukov, I. Yu.

    2011-08-15

    Electromagnetic cascades attract a lot of attention as an important quantum electrodynamics effect that will reveal itself in various electromagnetic field configurations at ultrahigh intensities. We study cascade dynamics in rotating electric field analytically and numerically. The kinetic equations for the electron-positron plasma and gamma-quanta are formulated. The scaling laws are derived and analyzed. For the cascades arising far above the threshold the dependence of the cascade parameters on the field frequency is derived. The spectra of high-energy cascade particles are calculated. The analytical results are verified by numerical simulations.

  4. Guiding of laser beams in plasmas by electromagnetic cascade compression

    NASA Astrophysics Data System (ADS)

    Kalmykov, S.; Shvets, G.

    2006-10-01

    The near-resonant beatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few- femtosecond electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red- and blue-shifted by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser phase, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. Thus, a train of high intensity radiation spikes with continually evolving longitudinal profile can be self- guided over several Rayleigh lengths in homogeneous plasma. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW show that achieving GeV energy is possible under realistic experimental conditions.

  5. Development of electromagnetic cascades in the atmosphere including the Landau-Pomeranchuk-Migdal effect

    NASA Technical Reports Server (NTRS)

    Streitmatter, R. E.; Stephens, S. A.

    1985-01-01

    Numerical solutions have been obtained for the one-dimensional atmospheric electromagnetic cascade diffusion equations, including the Landau-Pomeranchuk-Migdal and screening effects. Spectra produced by primary gamma rays of various energies are given at a number of deths in the atmosphere.

  6. Lateral distortions of electromagnetic cascades in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Porter, L. G.; Levit, L. B.; Jones, W. V.; Huggett, R. W.; Barrowes, S. C.

    1975-01-01

    Electromagnetic cascades in a lead-emulsion chamber have been studied to determine the effect of air gaps on the upstream sides of the emulsions. Such air gaps cause a change in the form of the radial distribution of electron tracks, making cascades appear older and giving incorrect energy estimates. The number of tracks remaining within a radius r was found to vary as exp(-g/G), where g is the gap thickness. The characteristic gap thickness in mm is G = 3.04 + 1.30 ln (Err per GeV per sq mm) where E is the energy of the initiating gamma ray. Use of this relation provides a significant correction to cascade-energy estimates and allows one to calculate the effect of different gap thicknesses on the energy threshold for visual detection of cascades.

  7. High-energy electromagnetic cascades in extragalactic space: Physics and features

    NASA Astrophysics Data System (ADS)

    Berezinsky, V.; Kalashev, O.

    2016-07-01

    Using the analytic modeling of the electromagnetic cascades compared with more precise numerical simulations, we describe the physical properties of electromagnetic cascades developing in the universe on cosmic microwave background and extragalactic background light radiations. A cascade is initiated by very-high-energy photon or electron, and the remnant photons at large distance have two-component energy spectrum, ∝E-2 (∝E-1.9 in numerical simulations) produced at the cascade multiplication stage and ∝E-3 /2 from Inverse Compton electron cooling at low energies. The most noticeable property of the cascade spectrum in analytic modeling is "strong universality," which includes the standard energy spectrum and the energy density of the cascade ωcas as its only numerical parameter. Using numerical simulations of the cascade spectrum and comparing it with recent Fermi LAT spectrum, we obtained the upper limit on ωcas stronger than in previous works. The new feature of the analysis is the "Emax rule." We investigate the dependence of ωcas on the distribution of sources, distinguishing two cases of universality: the strong and weak ones.

  8. Measurement of the nuclear electromagnetic cascade development in glass at energies above 200 GeV

    NASA Technical Reports Server (NTRS)

    Gillespie, C. R.; Huggett, R. W.; Humphreys, D. R.; Jones, W. V.; Levit, L. B.

    1971-01-01

    The longitudinal development of nuclear-electromagnetic cascades with energies greater than 200 GeV was measured in a low-Z (glass) absorber. This was done in the course of operating an ionization spectrometer at mountain altitude in an experiment to study the properties of gamma rays emitted from individual interactions at energies around 10,000 GeV. The ionization produced by a cascade is sampled by 20 sheets of plastic scintillator spaced uniformly in depth every 2.2 radiation lengths. Adjacent pairs of scintillators are viewed by photomultipliers which measure the mean ionization produced by an individual cascade in 10 layers each 1.1 interaction length (4.4 radiation lengths) thick. The longitudinal development of the cascades was measured for about 250 cascades having energies ranging from 200 GeV to 2500 GeV. The observations are compared with the predictions of calculations made for this specific spectrometer using a three-dimensional Monte Carlo model of the nuclear-electromagnetic cascade.

  9. Numerical analysis of electromagnetic cascades in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Plyasheshnikov, A. V.; Vorobyev, K. V.

    1985-01-01

    A new calculational scheme of the Monte Carlo method assigned for the investigation of the development of high and extremely high energy electromagnetic cascades (EMC) in the matter was elaborated. The scheme was applied to the analysis of angular and radial distributions of EMC electrons in the atmosphere. By means of this scheme the EMC development in dense medium is investigated and some preliminary data are presented on the behavior of EMC in emulsion chambers. The results of more detailed theoretical analysis of the EMC development in emulsion chambers are discussed.

  10. Electromagnetic cascades propagating from low-redshift blazars

    NASA Astrophysics Data System (ADS)

    Orellana, M.; Pellizza, L. J.; Romero, G. E.; Tueros, M.; Medina, M. C.; Pedrosa, S. E.

    2015-08-01

    It has been established that the Extragalactic Background Light attenuates the very high-energy photons emitted by blazars through pair production. The pairs are deflected by the Extragalactic Magnetic Field (EGMF) and cooled down by Inverse Compton scattering with the Cosmic Microwave Background (CMB) photons while they develop an electromagnetic cascade. The EGMF may also take out energy from the pairs in the form of synchrotron radiation. The originally emitted spectrum, the source extent and the arriving time of the photons are modified by such cascades. In order to study this problem we assume the blazar original emission to follow a power-law with exponential cutoff, and track the three-dimensional trajectories of each particle and photon in the cascade. In this work we describe the results of numerical simulations regarding the -ray propagation through Mpc scales, making focus on the construction of the outcoming spectrum which results from the energy conservation and thus combines the information from the different channels of energy losses. Different spectra arise when varying the EGMF strength.

  11. The electromagnetic component of albedo from superhigh energy cascades in dense media

    NASA Technical Reports Server (NTRS)

    Golynskaya, R. M.; Hein, L. A.; Plyasheshnikov, A. V.; Vorobyev, K. V.

    1985-01-01

    Albedo from cascades induced in iron by high energy gamma quanta were Monte Carlo simulated. Thereafter the albedo electromagnetic component from proton induced cascades were calculated analytically. The calculations showed that the albedo electromagnetic component increases more rapidly than the nuclear active component and will dominate at sufficiently high energies.

  12. Electromagnetic cascades in the magnetosphere of a very young pulsar - A model for the positron production near the Galactic center

    NASA Technical Reports Server (NTRS)

    Mastichiadis, Apostolos; Brecher, Kenneth; Marscher, Alan P.

    1987-01-01

    A detailed model for positron production by a young pulsar is presented. It is shown that electromagnetic cascades can develop in a young pulsar's magnetosphere, and the model results are applied to the pulsar which is hypothesized to lie near the Galactic center. It is found that such a pulsar would be expected to produce relatively low energy electron-positron pairs with an efficiency rating high enough to explain the observed luminosity of the Galactic center annihilation line. Virtually all of the gamma ray continuum radiation produced in the cascades would be beamed along the magnetic poles of the neutron star, and therefore probably would not be observed from earth. Some observational predictions generated by the proposed model for the Galactic center positron source are given.

  13. Laser frequency stabilization to excited state transitions using electromagnetically induced transparency in a cascade system

    SciTech Connect

    Abel, R. P.; Mohapatra, A. K.; Bason, M. G.; Pritchard, J. D.; Weatherill, K. J.; Raitzsch, U.; Adams, C. S.

    2009-02-16

    We demonstrate laser frequency stabilization to excited state transitions using cascade electromagnetically induced transparency. Using a room temperature Rb vapor cell as a reference, we stabilize a first diode laser to the D{sub 2} transition and a second laser to a transition from the intermediate 5P{sub 3/2} state to a highly excited state with principal quantum number n=19-70. A combined laser linewidth of 280{+-}50 kHz over a 100 {mu}s time period is achieved. This method may be applied generally to any cascade system and allows laser stabilization to an atomic reference in the absence of a direct absorption signal.

  14. Electromagnetically induced transparency in a five-level cascade system under Doppler broadening: an analytical approach

    NASA Astrophysics Data System (ADS)

    Khoa, Dinh Xuan; Van Trong, Pham; Van Doai, Le; Bang, Nguyen Huy

    2016-03-01

    We develop an analytical approach on electromagnetically induced transparency (EIT) in a Doppler broadened medium consisting of five-level cascade systems excited by a strong coupling and weak probe laser fields. In a weak field limit of the probe light, EIT spectrum is interpreted as functions of controllable parameters of the coupling light and temperature of the medium. The theoretical interpretation of EIT spectrum is applied to the case of 85Rb atoms and compared with available experimental observation. Such an analytical interpretation provides quantitative parameters to control properties of the Doppler broadened EIT medium, and it is useful to find related applications.

  15. Loophole to the universal photon spectrum in electromagnetic cascades and application to the cosmological lithium problem.

    PubMed

    Poulin, Vivian; Serpico, Pasquale Dario

    2015-03-01

    The standard theory of electromagnetic cascades onto a photon background predicts a quasiuniversal shape for the resulting nonthermal photon spectrum. This has been applied to very disparate fields, including nonthermal big bang nucleosynthesis (BBN). However, once the energy of the injected photons falls below the pair-production threshold the spectral shape is much harder, a fact that has been overlooked in past literature. This loophole may have important phenomenological consequences, since it generically alters the BBN bounds on nonthermal relics; for instance, it allows us to reopen the possibility of purely electromagnetic solutions to the so-called "cosmological lithium problem," which were thought to be excluded by other cosmological constraints. We show this with a proof-of-principle example and a simple particle physics model, compared with previous literature. PMID:25793793

  16. Electron Acceleration by Langmuir Waves Produced by a Decay Cascade

    NASA Astrophysics Data System (ADS)

    Krafft, C.; Volokitin, A. S.

    2016-04-01

    It was recently reported that a significant part of the Langmuir waveforms observed by the STEREO satellite during type III solar radio bursts are likely consistent with the occurrence of electrostatic decay instabilities, when a Langmuir wave { L } resonantly interacts with another Langmuir wave { L }\\prime and an ion sound wave { S }\\prime through the decay channel { L }\\to { L }\\prime +{ S }\\prime . Usually such wave–wave interactions occur in regions of the solar wind where the presence of electron beams can drive Langmuir turbulence to levels allowing waves { L } to decay. Moreover, such solar wind plasmas can present long-wavelength, randomly fluctuating density inhomogeneities or monotonic density gradients which can significantly modify the development of such resonant instabilities. If some conditions are met, the waves can encounter a second decay cascade (SDC) according to { L }\\prime \\to { L }\\prime\\prime +{ S }\\prime\\prime . Analytical estimates and observations based on numerical simulations show that the Langmuir waves { L }\\prime\\prime produced by this SDC can accelerate beam particles up to velocities and kinetic energies exceeding two times the beam drift velocity vb and half the initial beam energy, respectively. Moreover, this process can be particularly efficient if the scattering effects of waves on the background plasma inhomogeneities have already accelerated a sufficient amount of beam electrons up to the velocity range where the phase velocities of the { L }\\prime\\prime waves are lying. The paper shows that the conditions necessary for such process to occur can be easily met in solar wind plasmas if the beam velocities do not exceed around 35 times the plasma thermal velocity.

  17. Electromagnetic cascades around primordial black holes evaporating in the MHD regime and their observational appearance

    NASA Astrophysics Data System (ADS)

    Belyanin, A. A.; Kocharovsky, V. V.; Kocharovsky, Vl. V.

    2001-04-01

    Universal observational feature of microscopic primordial black holes is the Hawking emission which is believed to occur in the regime of noninteracting quark-gluon jets and their products. Then, stringent upper limit on the number density of primordial black holes seems to rule out the possibility of their discovery in the near future. Contrary to this widely accepted opinion, we show that, when the black-hole temperature exceeds 10 GeV, the charged particle outflow from a black hole becomes plasma and the magnetohydrodynamical regime of expansion can be realized. In this case, the kinetic energy of ejected particles can be converted into the 0.1-1 MeV γ-rays due to the synchrotron radiation and electromagnetic cascade in the close-to-equipartition turbulent magnetic field. Also, the cascade leads to the significant increase of photon flux in the sub-GeV range. As a result, a black hole with mass below 1012 g becomes a transient γ-ray source with luminosity growing according to the explosive-type law. We show that up to several per cent of the gamma-ray bursts detected by BATSE can be associated with evaporating black holes with temperature exceeding ~1 TeV and masses below 1010 g, located at distances within ~1 pc from the Earth. .

  18. The Impact of Electromagnetic Cascades of Very-high Energy Gamma Rays on the Extragalactic Gamma-ray Background

    NASA Technical Reports Server (NTRS)

    Venters, Tonia

    2012-01-01

    As very high energy (VHE) photons propagate through the extragalactic background light (EBL), they interact with the soft photons of the EBL and initiate electromagnetic cascades of photons and electrons. The collective intensity of a cosmological population emitting at VHEs (such as blazars) will be attenuated at the highest energies through interactions with the EBL and enhanced at lower energies by the resulting cascade. As such, depending on the space density and spectra of the sources and the model of the EBL, cascade radiation can provide a significant contribution to the extragalactic gamma-ray background (EGB). Through deflections of the charged particles of the cascade, an intergalactic magnetic field (IGMF) may leave an imprint on the anisotropy properties of the EGB. The impact of a strong IGMF is to isotropize lower energy cascade photons, inducing a modulation in the anisotropy energy spectrum of the EGB. We discuss the implications of cascade radiation for the origins of the EGB and the nature of the IGMF, as well as insight that will be provided by data from the Fermi Large Area Telescope in the upcoming years.

  19. Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

    NASA Astrophysics Data System (ADS)

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2013-06-01

    The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

  20. ELMAG: A Monte Carlo simulation of electromagnetic cascades on the extragalactic background light and in magnetic fields

    NASA Astrophysics Data System (ADS)

    Kachelrieß, M.; Ostapchenko, S.; Tomàs, R.

    2012-04-01

    A Monte Carlo program for the simulation of electromagnetic cascades initiated by high-energy photons and electrons interacting with extragalactic background light (EBL) is presented. Pair production and inverse Compton scattering on EBL photons as well as synchrotron losses and deflections of the charged component in extragalactic magnetic fields (EGMF) are included in the simulation. Weighted sampling of the cascade development is applied to reduce the number of secondary particles and to speed up computations. As final result, the simulation procedure provides the energy, the observation angle, and the time delay of secondary cascade particles at the present epoch. Possible applications are the study of TeV blazars and the influence of the EGMF on their spectra or the calculation of the contribution from ultrahigh energy cosmic rays or dark matter to the diffuse extragalactic gamma-ray background. As an illustration, we present results for deflections and time delays relevant for the derivation of limits on the EGMF.

  1. Exact Electromagnetic Fields Produced by a Finite Wire with Constant Current

    ERIC Educational Resources Information Center

    Jimenez, J. L.; Campos, I.; Aquino, N.

    2008-01-01

    We solve exactly the problem of calculating the electromagnetic fields produced by a finite wire with a constant current, by using two methods: retarded potentials and Jefimenko's formalism. One result in this particular case is that the usual Biot-Savart law of magnetostatics gives the correct magnetic field of the problem. We also show…

  2. Self-organized electromagnetic field structures in laser-produced counter-streaming plasmas

    NASA Astrophysics Data System (ADS)

    Kugland, N. L.; Ryutov, D. D.; Chang, P.-Y.; Drake, R. P.; Fiksel, G.; Froula, D. H.; Glenzer, S. H.; Gregori, G.; Grosskopf, M.; Koenig, M.; Kuramitsu, Y.; Kuranz, C.; Levy, M. C.; Liang, E.; Meinecke, J.; Miniati, F.; Morita, T.; Pelka, A.; Plechaty, C.; Presura, R.; Ravasio, A.; Remington, B. A.; Reville, B.; Ross, J. S.; Sakawa, Y.; Spitkovsky, A.; Takabe, H.; Park, H.-S.

    2012-11-01

    Self-organization occurs in plasmas when energy progressively transfers from smaller to larger scales in an inverse cascade. Global structures that emerge from turbulent plasmas can be found in the laboratory and in astrophysical settings; for example, the cosmic magnetic field, collisionless shocks in supernova remnants and the internal structures of newly formed stars known as Herbig-Haro objects. Here we show that large, stable electromagnetic field structures can also arise within counter-streaming supersonic plasmas in the laboratory. These surprising structures, formed by a yet unexplained mechanism, are predominantly oriented transverse to the primary flow direction, extend for much larger distances than the intrinsic plasma spatial scales and persist for much longer than the plasma kinetic timescales. Our results challenge existing models of counter-streaming plasmas and can be used to better understand large-scale and long-time plasma self-organization.

  3. Simulations of electromagnetic emissions produced in a thin plasma by a continuously injected electron beam

    NASA Astrophysics Data System (ADS)

    Annenkov, V. V.; Timofeev, I. V.; Volchok, E. P.

    2016-05-01

    In this paper, electromagnetic emissions produced in a thin beam-plasma system are studied using two-dimensional particle-in-cell simulations. For the first time, the problem of emission generation in such a system is considered in a realistic formulation allowing for the continuous injection of a relativistic electron beam through a plasma boundary. Specific attention is given to the thin plasma case in which the transverse plasma size is comparable to the typical wavelength of beam-driven oscillations. Such a case is often implemented in laboratory beam-plasma experiments and has a number of peculiarities. Emission from a thin plasma does not require intermediate generation of the electromagnetic plasma eigenmodes, as in an infinite case, and is more similar to the regular antenna radiation. In this work, we determine how efficiently the fundamental and the second harmonic emissions can be generated in previously modulated and initially homogeneous plasmas.

  4. Construction of radiation-modified phase diagrams under cascade-producing irradiation: application to Zr-Nb alloy

    NASA Astrophysics Data System (ADS)

    Turkin, Anatole A.; Buts, Alexander V.; Bakai, Alexander S.

    2002-10-01

    A general theoretical formalism developed for the description of phase stability alteration in substitutional binary alloys under irradiation is applied to Zr-Nb alloys. We examine the stability of β-Nb precipitates in Zr-Nb alloy subjected to the cascade-producing irradiation. The results of phase stability studies are presented in the form of radiation-modified phase diagram. Evolution of large precipitates (as compared to the size of cascade region) differs from that of small precipitates. In the radiation-modified phase diagram there exists a low temperature boundary for stability of large precipitates, the location of which depends on interface type and displacement rate. Above this boundary large precipitates coarsen with radiation-enhanced rate. Below it the alloy is maintained in a quasi-steady-state of supersaturated solid solution with a population of fine-grained precipitates. The competition between processes of cascade destruction; nucleation and growth of coherent precipitates; and coherency loss can lead to the formation of the distribution of fine-grained precipitates with slowly varying parameters. In particular, such a distribution may form in Zr-Nb alloys under thermal reactor conditions.

  5. Coherent frequency combs produced by self frequency modulation in quantum cascade lasers

    SciTech Connect

    Khurgin, J. B.; Dikmelik, Y.; Hugi, A.; Faist, J.

    2014-02-24

    One salient characteristic of Quantum Cascade Laser (QCL) is its very short τ ∼ 1 ps gain recovery time that so far thwarted the attempts to achieve self-mode locking of the device into a train of single pulses. We show theoretically that four wave mixing, combined with the short gain recovery time causes QCL to operate in the self-frequency-modulated regime characterized by a constant power in time domain and stable coherent comb in the frequency domain. Coherent frequency comb may enable many potential applications of QCL's in sensing and measurement.

  6. Rayleigh-Taylor-Induced Electromagnetic Fields in Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Manuel, Mario J.-E.

    Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role

  7. Diffuse ions produced by electromagnetic ion beam instabilities. [in earth's bow shock

    NASA Technical Reports Server (NTRS)

    Winske, D.; Leroy, M. M.

    1984-01-01

    The evolution of the electromagnetic ion beam instability driven by the reflected ion component backstreaming away from the earth's bow shock into the foreshock region is studied by means of computer simulation. The linear and quasi-linear stages of the instability are found to be in good agreement with known results for the resonant mode propagating parallel to the beam along the magnetic field and with theory developed in this paper for the nonresonant mode, which propagates antiparallel to the beam direction. The quasi-linear stage, which produces large amplitude delta B approximately B, sinusoidal transverse waves and 'intermediate' ion distributions, is terminated by a nonlinear phase in which strongly nonlinear, compressive waves and 'diffuse' ion distributions are produced. Additional processes by which the diffuse ions are accelerated to observed high energies are not addressed. The results are discussed in terms of the ion distributions and hydromagnetic waves observed in the foreshock of the earth's bow shock and of interplanetary shocks.

  8. Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

    SciTech Connect

    Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander; Linscott, Ivan; Strauss, David; Lauben, David; Srama, Ralf; Mocker, Anna; Bugiel, Sebastian

    2013-09-15

    Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼10{sup 28} m{sup −3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

  9. [A Case of an Adrenocorticotropic Hormone-Producing Pituitary Adenoma Removed via Electromagnetic-Guided Neuroendoscopy].

    PubMed

    Tomita, Yusuke; Kurozumi, Kazuhiko; Terasaka, Tomohiro; Inagaki, Kenichi; Otsuka, Fumio; Date, Isao

    2016-06-01

    The use of navigation systems is safe and reliable for neurological surgery. We performed endoscopic transsphenoidal surgery to totally resect an adrenocorticotropic hormone (ACTH)-producing pituitary adenoma associated with oculomotor nerve palsy. A 70-year-old woman developed right ptosis 4 months before admission. She developed anisocoria 2 months later and was referred to the department of neurology from clinic. Brain magnetic resonance imaging(MRI)showed an intrasellar tumor that partially invaded the right cavernous sinus, and she was then referred to our department. She exhibited a round face ("moon face") and central obesity. Laboratory test results showed a high urinary cortisol level and high serum ACTH level, and neither the serum cortisol nor ACTH level was suppressed by a low-dose dexamethasone test. We performed transsphenoidal surgery using high-dimensional endoscopy under electromagnetic navigation. The tumor invading the cavernous sinus was visualized via endoscopy and confirmed on navigation using a flexible needle probe. Postoperative MRI showed total removal of the tumor, and the serum ACTH level recovered to the normal range. The patient's right oculomotor palsy resolved within 1 week postoperatively. In summary, electromagnetic navigation was useful for total resection of a pituitary tumor invading the cavernous sinus, contributing to normalization of the ACTH level and improvement in neurological symptoms. PMID:27270145

  10. Analytical-numerical methods of calculations of energy and three-dimensional particle distributions in electromagnetic cascades

    NASA Technical Reports Server (NTRS)

    Ivanenko, I. P.; Kanevsky, B. L.; Roganova, T. M.; Sizov, V. V.; Triphonova, S. V.

    1985-01-01

    Analytical and numerical methods of calculation of the energy and three dimensional EPS characteristics are reported. The angular and lateral functions of electrons in EPS have been obtained by the Landau and small angle approximations A and B and compared with earlier data. A numerical method of solution of cascade equations for the EPS distribution function moments has been constructed. Considering the equilibrium rms angle as an example, errors appearing when approximating the elementary process cross sections by their asymptotic expressions are analyzed.

  11. Monte Carlo simulation of the nuclear-electromagnetic cascade development and the energy response of ionization spectrometers

    NASA Technical Reports Server (NTRS)

    Jones, W. V.

    1973-01-01

    Modifications to the basic computer program for performing the simulations are reported. The major changes include: (1) extension of the calculations to include the development of cascades initiated by heavy nuclei, (2) improved treatment of the nuclear disintegrations which occur during the interactions of hadrons in heavy absorbers, (3) incorporation of accurate multi-pion final-state cross sections for various interactions at accelerator energies, (4) restructuring of the program logic so that calculations can be made for sandwich-type detectors, and (5) logic modifications related to execution of the program.

  12. On the electromagnetic fields produced by marine frequency domain controlled sources

    NASA Astrophysics Data System (ADS)

    Chave, Alan D.

    2009-12-01

    In recent years, marine controlled source electromagnetics (CSEM) has found increasing use in hydrocarbon exploration due to its ability to detect thin resistive zones beneath the seafloor. Although it must be recognized that the quantitative interpretation of marine CSEM data over petroleum-bearing formations will typically require 2-D surveys and 2-D or 3-D modelling, the use of the 1-D approximation is useful under some circumstances and provides considerable insight into the physics of marine CSEM. It is the purpose of this paper to thoroughly explore the 1-D solutions for all four fundamental source types-vertical and horizontal, electric and magnetic dipole (VED, HED, VMD and HMD)-using a set of canonical reservoir models that encompass brine to weak to strong hydrocarbon types. The paper introduces the formalism to solve the Maxwell equations for a 1-D structure in terms of independent and unique toroidal and poloidal magnetic modes that circumscribe the salient diffusion physics. Green's functions for the two modes from which solutions for arbitrary source current distributions can be constructed are derived and used to obtain the electromagnetic (EM) fields produced by finite VED, HED, VMD and HMD sources overlying an arbitrary 1-D electrical structure. Field behaviour is analysed using the Poynting vector that represents the time-averaged flow of energy through the structure and a polarization ellipse decomposition of the triaxial seafloor EM field that is a complete field description. The behaviour of the two EM modes using unimodal VED and VMD sources is presented. The paper closes by extending these results to the bimodal HED and HMD sources.

  13. Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression.

    PubMed

    Pall, Martin L

    2016-09-01

    Non-thermal microwave/lower frequency electromagnetic fields (EMFs) act via voltage-gated calcium channel (VGCC) activation. Calcium channel blockers block EMF effects and several types of additional evidence confirm this mechanism. Low intensity microwave EMFs have been proposed to produce neuropsychiatric effects, sometimes called microwave syndrome, and the focus of this review is whether these are indeed well documented and consistent with the known mechanism(s) of action of such EMFs. VGCCs occur in very high densities throughout the nervous system and have near universal roles in release of neurotransmitters and neuroendocrine hormones. Soviet and Western literature shows that much of the impact of non-thermal microwave exposures in experimental animals occurs in the brain and peripheral nervous system, such that nervous system histology and function show diverse and substantial changes. These may be generated through roles of VGCC activation, producing excessive neurotransmitter/neuroendocrine release as well as oxidative/nitrosative stress and other responses. Excessive VGCC activity has been shown from genetic polymorphism studies to have roles in producing neuropsychiatric changes in humans. Two U.S. government reports from the 1970s to 1980s provide evidence for many neuropsychiatric effects of non-thermal microwave EMFs, based on occupational exposure studies. 18 more recent epidemiological studies, provide substantial evidence that microwave EMFs from cell/mobile phone base stations, excessive cell/mobile phone usage and from wireless smart meters can each produce similar patterns of neuropsychiatric effects, with several of these studies showing clear dose-response relationships. Lesser evidence from 6 additional studies suggests that short wave, radio station, occupational and digital TV antenna exposures may produce similar neuropsychiatric effects. Among the more commonly reported changes are sleep disturbance/insomnia, headache, depression

  14. Influences of Electromagnetic Articulography Sensors on Speech Produced by Healthy Adults and Individuals with Aphasia and Apraxia

    ERIC Educational Resources Information Center

    Katz, William F.; Bharadwaj, Sneha V.; Stettler, Monica P.

    2006-01-01

    Purpose: This study examined whether the intraoral transducers used in electromagnetic articulography (EMA) interfere with speech and whether there is an added risk of interference when EMA systems are used to study individuals with aphasia and apraxia. Method: Ten adult talkers (5 individuals with aphasia/apraxia, 5 controls) produced 12 American…

  15. The search for interstitial dislocation loops produced in displacement cascades at 20K in copper.

    SciTech Connect

    Kirk, M. A.; Jenkins, M. L.; Fukushima, H.; Materials Science Division; Univ. of Oxford; Hiroshima Univ.

    2000-01-01

    A low-temperature in situ ion-irradiation and annealing experiment has been performed in copper. Most clusters which persisted through an anneal to 120 K showed no size changes within the resolution (0.5 nm) of a new weak-beam sizing technique. Of the 55 defects measured under a range of weakly diffracting conditions, seven showed measurable size decreases while three showed size increases. We argue that these clusters are likely to be of vacancy and interstitial nature, respectively. Also on annealing to 120 K a fraction of about 25% of the clusters formed by irradiation with 600 kV Cu+ ions at 20 K disappeared, while a similar number of clusters appeared at different locations. The remaining defects persisted through the anneal, sometimes however with modified morphologies. Video microscopy suggested that the disappearance and appearance of clusters occurred gradually and was unlikely to be due to loop movement. Some arguments on the possible nature of these clusters are presented. On warming specimens to room temperature, a high density of small stacking-fault tetrahedra appeared close to the electron-exit surface of the foil in regions which had been exposed to the electron beam at low temperatures. These are most likely due to the clustering of vacancies produced by sputtering at the back surface.

  16. Plasma channel produced by femtosecond laser pulses as a medium for amplifying electromagnetic radiation of the subterahertz frequency range

    SciTech Connect

    Bogatskaya, A V; Volkova, E A; Popov, A M

    2013-12-31

    The electron energy distribution function in the plasma channel produced by a femtosecond laser pulse with a wavelength of 248 nm in atmospheric-pressure gases was considered. Conditions were determined whereby this channel may be employed for amplifying electromagnetic waves up to the terahertz frequency range over the energy spectrum relaxation time ∼10{sup -7} s. Gains were calculated as functions of time and radiation frequency. The effect of electron – electron collisions on the rate of relaxation processes in the plasma and on its ability to amplify the electromagnetic radiation was investigated. (interaction of laser radiation with matter)

  17. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Entanglement Properties Between Two Spatially Separated Atoms with Cascade Configuration in Free Space

    NASA Astrophysics Data System (ADS)

    Yang, Guo-Hui; Zhang, Jun-Feng; Miao, Xiang-Yang; Zhou, Ling

    2010-03-01

    We investigate the entanglement properties between two identical atoms with cascade configuration through the retarded dipole-dipole interaction in free space when their spatial separation is on the order of radiation wavelength or less. We analyze the function of Hamiltonian induced by dipole-dipole interaction. By solving master equation, we show that the spontaneous emission induce entanglement and destroy entanglement too. We also show the long life time of entanglement within cascade configuration.

  18. Optimization of the Electromagnetic (EM) Perturbative Effects Produced by High-Frequency Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Li, Jin; Zhang, Lu; Wen, Hao

    2016-03-01

    For the relic gravitational waves in high frequency band, we survey the electromagnetic resonance effect generated from the high frequency gravitational waves, which can be described in the transverse perturbative photon fluxes. Under the fixed tensor-scalar ratio r = 0.2, spectral index n t = 0 and running index α t = 0.01, we discuss several properties and quantity changes of the transverse perturbative photon fluxes, which can be improved significantly through setting the longitudinal magnetic component of background EM field in the standard gaussian form, and wave impedance analysis on the transverse direction. Through the theoretical calculation, the transverse perturbative photon fluxes can reach up to 103 s -1 with some optimal parameters such as waist of EM field W 0 = 0.05m, initial stochastic phase of gravitational waves δ = (0.21 + n) π( n = 0,1,2...). Furthermore the interference of the background transverse photon fluxes can be removed completely through establishing a suitable wave impedance function.

  19. The immune response of women with prolonged exposure to electromagnetic fields produced by radiotelevision broadcasting stations.

    PubMed

    Boscolo, P; Di Giampaolo, L; Di Donato, A; Antonucci, A; Paiardini, G; Morelli, S; Vasile, R; Spagnoli, G; Reale, M; Dadorante, V; Kouri, M; Di Gioacchino, M

    2006-01-01

    Twelve women, five of them housewives, exposed in their residences to electromagnetic fields (EMFs)emitted by radio-television broadcasting stations for a mean period of 13 years, were investigated. The EMFs in the balconies of the homes were (mean + S.D.) 4.3 + 1.4 V/m in the year 2000 and 3.7 + 1.3 V/m in 2005, while the exposure in the nearby area was <2.0 V/m. The EMF exposed women showed in 2000 reduced blood NK lymphocytes as well as PHA stimulated PBMC proliferation and IL-2 and IFN-gamma release. In the year 2005, the EMF exposed women and 48 control women with similar ages(mean 43 years), smoking habits, atopy and social level were investigated. State (temporary) and trait(tendency of the personality) anxiety were determined by STAI I and II, respectively. Blood cytotoxic activity and lymphocyte subsets were also determined. The ratio STAI I/STAI II of the EMF exposed group was lower than that of the control group. The blood cytotoxic activity of the exposed women was lower (p<0.01), percent of B CD45+-CD19+ lymphocytes higher and percent of CD45+-CD3+-CD8+ cells lower (p<0.05). Moreover, cytotoxic activity/CD45+-CD16+-56+ NK lymphocytes of the controls was negatively correlated with STAI I and STAI II (p<0.001). In conclusion, this study demonstrates reduced blood cytotoxic activity and increased trait anxiety in relation to state anxiety in EMF exposed women. An effect of EMFs on immune functions, in part mediated by nervous mechanisms, may be hypothesized. However, the influence of lifestyle may not be excluded. PMID:17291406

  20. Evaluation of mouse embryos produced in vitro after electromagnetic waves exposure; Morphometric study

    PubMed Central

    Rostamzadeh, Ayoob; Mohammadi, Mohsen; Ahmadi, Reza; Nazari, Afshin; Ghaderi, Omar; Anjomshoa, Maryam

    2016-01-01

    Introduction Today, the use of electromagnetic waves in medical diagnostic devices, such as magnetic resonance imaging (MRI), has increased, and many of its biological effects have been reported. The aim of the present study was to assess the biological effects of 1.5 Tesla (T) magnetic resonance imaging (MRI) on fertility and reproductive parameters. Methods Eighty adult male and female NMRI mice (NMRI: Naval Medical Research Institute) of age 6–8 weeks were studied and randomly divided into two study and control groups. After confirmation of pregnancy, the mice in the study group were exposed to the MRI (1.5 T) machine’s waves over the next three weeks, once a week for 36 minutes. One day and thirty-five days after the last radiation, the mice were killed in order to do the in vitro fertilization (IVF) by neck beads’ displacement and the impact on the evolution of embryos, and its quality was studied. Data were analyzed using SPSS version 20 and the significance level of less than 0.05 was considered. Results Embryo morphometry showed that the total diameter and the cytoplasm diameter of the study group embryos suffered significant reduction compared to the control group, 1 day after the last irradiation (p < 0.05), but the diameter of the perivitelline space of this group’s embryos had a significant increase (p < 0.05). The qualitative results during 35 days after irradiation showed that morphologically parameters of the embryos in the study group had no significant differences from the control group. Conclusion Exposure to MRI irradiation can transiently disturb the development of mouse embryos and fertility, but these effects are reversible 35 days after the last irradiation. PMID:26955439

  1. Laminar shear flow increases hydrogen sulfide and activates a nitric oxide producing signaling cascade in endothelial cells.

    PubMed

    Huang, Bin; Chen, Chang-Ting; Chen, Chi-Shia; Wang, Yun-Ming; Hsieh, Hsyue-Jen; Wang, Danny Ling

    2015-09-01

    Laminar shear flow triggers a signaling cascade that maintains the integrity of endothelial cells (ECs). Hydrogen sulfide (H2S), a new gasotransmitter is regarded as an upstream regulator of nitric oxide (NO). Whether the H2S-generating enzymes are correlated to the enzymes involved in NO production under shear flow conditions remains unclear as yet. In the present study, the cultured ECs were subjected to a constant shear flow (12 dyn/cm(2)) in a parallel flow chamber system. We investigated the expression of three key enzymes for H2S biosynthesis, cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), and 3-mercapto-sulfurtransferase (3-MST). Shear flow markedly increased the level of 3-MST. Shear flow enhanced the production of H2S was determined by NBD-SCN reagent that can bind to cysteine/homocystein. Exogenous treatment of NaHS that can release gaseous H2S, ECs showed an increase of phosphorylation in Akt(S473), ERK(T202/Y204) and eNOS(S1177). This indicated that H2S can trigger the NO-production signaling cascade. Silencing of CSE, CBS and 3-MST genes by siRNA separately attenuated the phosphorylation levels of Akt(S473) and eNOS(S1177) under shear flow conditions. The particular mode of shear flow increased H2S production. The interplay between H2S and NO-generating enzymes were discussed in the present study. PMID:26212441

  2. The reflection of an electromagnetic wave from the self-produced plasma

    SciTech Connect

    Mirzaie, M.; Shokri, B.; Rukhadze, A. A.

    2010-01-15

    The dynamic behavior of a high power microwave beam propagating through a gaseous medium, which is ionized in the wave field is investigated. By solving the wave equation, the reflection index of the produced plasma is obtained. It is shown that the cut off condition is different from that of the steady state approximation. The reflection index is less than unity when the plasma density reaches the critical value estimated in the steady state approximation. So, the wave can still propagate through the plasma. By comparing the reflection indexes in the presence and absence of the time delay of the ionization process at different points of the medium, it is shown that it becomes unity much later in the first case. Therefore, the wave propagation takes much more time and consequently the medium is ionized much more.

  3. Clarification of THz Electromagnetic Radiation mechanism from the Laser Produced Plasma

    NASA Astrophysics Data System (ADS)

    Hideta, Masataka; Hyuga, Yusuke; Sentoku, Yasuhiko; Yugami, Noboru

    2015-11-01

    Conical forward Terahertz radiation from ultra-short pulse laser produced plasma has been observed. The radiation frequency is smaller than the plasma frequency that is estimated by the initial gas density and laser intensity. This radiation mechanism has not been clarified. To study the radiation mechanism, 2D PIC code is used. The radiation is described by the following equation, ∇2 -1/c2∂2/∂t2 +ωp2/c2 B =μ0 e∇n × v where, ωp, n and v represent the plasma frequency, the plasma density and the electron velocity, respectively. The right hand side is considered as the radiation source which strongly depend on the gradient of the plasma density and the electron velocity. In the experiment, the laser propagates with creating the plasma, the plasma density profile is a function of the radial direction. Therefore, the strong gradient is at the edge of the plasma column, not the center of the plasma, the radiation is expected to generate there and its frequency is also equal to the local plasma frequency. The 2D calculation shows the EM wave is generated around the edge of the plasma column and its frequency is lower than the plasma frequency.

  4. Characterization and Measurement of the Spatial Distribution of Electromagnetic Fields Produced by Focussing Elements.

    NASA Astrophysics Data System (ADS)

    Haddock, Christopher

    During the late 1970's in the wake of fossil fuel price increases, renewed interest in the generation of renewable forms of energy was aroused. In order to study new methods of converting solar energy in particular to more useful forms, a solar concentrator facility was built. The purpose of the facility is to concentrate the intensity of beams of sunlight by a factor of several thousand using a system of reflecting and focussing mirrors and to use this technique in the direct generation of electricity. The intensity variation of the concentrated sunlight at the focus of the system was measured with a radiometric instrument capable of measuring very high intensities. The results of the mapping were compared with a theoretical model which used the optical figuring parameters of the system as input. The results showed that the concentrated intensity as a function of position can be accurately predicted given the incident intensity and a representative value of the clearness of the sky for that day. At the start of the technology transfer process it was decided that a modern analogue to digital converter (ADC), an integral part of a high accuracy digital multimeter, could perform data collection quickly and accurately so that recording of pulse information could take place in real time. Thus electronic integrators, which can be inherently unstable and represent the weak link in this type of apparatus are no longer required in the measurement process. Furthermore, advances in microcomputer technology, both hardware and software, made it possible to produce a completely automated field mapping system, including data analysis and logging, for approximately 1/5th the price of other competitive contemporary systems. At the same time this strategy eliminated the long lead time required for developing an appropriate software package. (Abstract shortened with permission of author.).

  5. Visualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysicsa)

    NASA Astrophysics Data System (ADS)

    Kugland, N. L.; Ross, J. S.; Chang, P.-Y.; Drake, R. P.; Fiksel, G.; Froula, D. H.; Glenzer, S. H.; Gregori, G.; Grosskopf, M.; Huntington, C.; Koenig, M.; Kuramitsu, Y.; Kuranz, C.; Levy, M. C.; Liang, E.; Martinez, D.; Meinecke, J.; Miniati, F.; Morita, T.; Pelka, A.; Plechaty, C.; Presura, R.; Ravasio, A.; Remington, B. A.; Reville, B.; Ryutov, D. D.; Sakawa, Y.; Spitkovsky, A.; Takabe, H.; Park, H.-S.

    2013-05-01

    Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven by kinetic plasma instabilities. However, the development of small-scale plasma processes into large-scale structures, such as a collisionless shock, is not well understood. It is also unknown to what extent collisionless shocks contain macroscopic fields with a long coherence length. For these reasons, it is valuable to explore collisionless shock formation, including the growth and self-organization of fields, in laboratory plasmas. The experimental results presented here show at a glance with proton imaging how macroscopic fields can emerge from a system of supersonic counter-streaming plasmas produced at the OMEGA EP laser. Interpretation of these results, plans for additional measurements, and the difficulty of achieving truly collisionless conditions are discussed. Future experiments at the National Ignition Facility are expected to create fully formed collisionless shocks in plasmas with no pre-imposed magnetic field.

  6. Visualizing electromagnetic fields in laser-produced counter-streaming plasma experiments for collisionless shock laboratory astrophysics

    SciTech Connect

    Kugland, N. L.; Ross, J. S.; Glenzer, S. H.; Huntington, C.; Martinez, D.; Plechaty, C.; Remington, B. A.; Ryutov, D. D.; Park, H.-S.; Chang, P.-Y.; Fiksel, G.; Froula, D. H.; Drake, R. P.; Grosskopf, M.; Kuranz, C.; Gregori, G.; Meinecke, J.; Reville, B.; Koenig, M.; Pelka, A.; and others

    2013-05-15

    Collisionless shocks are often observed in fast-moving astrophysical plasmas, formed by non-classical viscosity that is believed to originate from collective electromagnetic fields driven by kinetic plasma instabilities. However, the development of small-scale plasma processes into large-scale structures, such as a collisionless shock, is not well understood. It is also unknown to what extent collisionless shocks contain macroscopic fields with a long coherence length. For these reasons, it is valuable to explore collisionless shock formation, including the growth and self-organization of fields, in laboratory plasmas. The experimental results presented here show at a glance with proton imaging how macroscopic fields can emerge from a system of supersonic counter-streaming plasmas produced at the OMEGA EP laser. Interpretation of these results, plans for additional measurements, and the difficulty of achieving truly collisionless conditions are discussed. Future experiments at the National Ignition Facility are expected to create fully formed collisionless shocks in plasmas with no pre-imposed magnetic field.

  7. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Effect of Carried-Envelope Phase on Transient Process in a Cascade-Type System

    NASA Astrophysics Data System (ADS)

    Zheng, Li-Li; Yu, Ling-Yan

    2010-03-01

    This paper investigates the effect of carried-envelope phase on transient process in a cascade-type atomic system, which is driven by two ultrashort laser pulses (probe and signal laser). It is found that the one- and two-photon processes corresponding to pathway |0> → |1> and |0> → |1> → |2> can be enhanced or suppressed by modulating the carried-envelope phases of probe laser pulse. Our numerical results also show that the transient populations of two excited states can be periodically affected by the carried-envelope phase of probe laser pulse. With certain time, the partial population transfer between two exited states can be realized just by adjusting the carried-envelope phase of probe laser pulse.

  8. Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves

    DOEpatents

    Efthimion, Philip C.; Helfritch, Dennis J.

    1989-11-28

    An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of pressures, especially at atmospheric and high pressures includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a wave guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding wave structure and into the cavity acts on the plasma to push it away from the guiding wave structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of pressures.

  9. Oxygenation by COX-2 (cyclo-oxygenase-2) of 3-HETE (3-hydroxyeicosatetraenoic acid), a fungal mimetic of arachidonic acid, produces a cascade of novel bioactive 3-hydroxyeicosanoids

    PubMed Central

    2005-01-01

    Cyclo-oxygenases-1/2 (COX-1/2) catalyse the oxygenation of AA (arachidonic acid) and related polyunsaturated fatty acids to endoperoxide precursors of prostanoids. COX-1 is referred to as a constitutive enzyme involved in haemostasis, whereas COX-2 is an inducible enzyme expressed in inflammatory diseases and cancer. The fungus Dipodascopsis uninucleata has been shown by us to convert exogenous AA into 3(R)-HETE [3(R)-hydroxy-5Z,8Z,11Z,14Z-eicosatetraenoic acid]. 3R-HETE is stereochemically identical with AA, except that a hydroxy group is attached at its C-3 position. Molecular modelling studies with 3-HETE and COX-1/2 revealed a similar enzyme–substrate structure as reported for AA and COX-1/2. Here, we report that 3-HETE is an appropriate substrate for COX-1 and -2, albeit with a lower activity of oxygenation than AA. Oxygenation of 3-HETE by COX-2 produced a novel cascade of 3-hydroxyeicosanoids, as identified with EI (electron impact)–GC–MS, LC–MS–ES (electrospray) and LC–MS–API (atmospheric pressure ionization) methods. Evidence for in vitro production of 3-hydroxy-PGE2 (3-hydroxy-prostaglandin E2) was obtained upon infection of HeLa cells with Candida albicans at an MOI (multiplicity of infection) of 100. Analogous to interaction of AA and aspirin-treated COX-2, 3-HETE was transformed by acetylated COX-2 to 3,15-di-HETE (3,15-dihydroxy-HETE), whereby C-15 showed the (R)-stereochemistry. 3-Hydroxy-PGs are potent biologically active compounds. Thus 3-hydroxy-PGE2 induced interleukin-6 gene expression via the EP3 receptor (PGE2 receptor 3) in A549 cells, and raised cAMP levels via the EP4 receptor in Jurkat cells. Moreover, 3R,15S-di-HETE triggered the opening of the K+ channel in HTM (human trabecular meshwork) cells, as measured by the patch–clamp technique. Since many fatty acid disorders are associated with an ‘escape’ of 3-hydroxy fatty acids from the β-oxidation cycle, the production of 3-hydroxyeicosanoids may be critical in

  10. Cascade physics at CLAS12

    SciTech Connect

    Guo, Lei

    2009-01-01

    Cascade spectroscopy offers rich discovering opportunities that are essential to the current JLAB spectroscopy program at both CLAS, CLAS12 and GLUEX. Recent CLAS results have demonstrated the feasibility to study cascade resonances through photoproduction. The cross sections for the ground state cascade is observed to increase as a function of energy in the range of 2.8-5GeV. With the maximum achievable energy at CLAS12 with the current tagger being 6.3~GeV, cascade resonances up to 2.4~GeV are expected to be produced with reasonable rates. The possible addition of a RICH detector would certainly benefit physics programs requiring the detection of kaons, especially cascade physics.

  11. Cascaded humidified advanced turbine

    SciTech Connect

    Nakhamkin, M.; Swenson, E.C.; Cohn, A.; Bradshaw, D.; Taylor, R.; Wilson, J.M.; Gaul, G.; Jahnke, F.; Polsky, M.

    1995-05-01

    This article describes how, by combining the best features of simple- and combined-cycle gas turbine power plants, the CHAT cycle concept offers power producers a clean, more efficient and less expensive alternative to both. The patented cascaded advanced turbine and its cascaded humidified advanced turbine (CHAT) derivative offer utilities and other power producers a practical advanced gas turbine power plant by combining commercially-available gas turbine and industrial compressor technologies in a unique way. Compared to combined-cycle plants, a CHAT power plant has lower emissions and specific capital costs-approximately 20 percent lower than what is presently available. Further, CHAT`s operating characteristics are especially well-suited to load following quick start-up scenarios and they are less susceptible to power degradation from higher ambient air temperature conditions.

  12. Stopping pions in high-energy nuclear cascades.

    NASA Technical Reports Server (NTRS)

    Jones, W. V.; Johnson, D. P.; Thompson, J. A.

    1973-01-01

    Results of Monte Carlo calculations for the number and energy spectra of charged pions from nuclear-electromagnetic cascades developing in rock are presented for primary hadron energies ranging from 3 to 3000 GeV. These spectra are given as functions of the longitudinal depth in the absorber and the lateral distance from the cascade axis. The number of charged pions which stop in the absorber increases with the primary energy of the hadron initiating the cascade.

  13. Frequency Upshift and Radiation of the THz Electromagnetic Wave via an Ultrashort-Laser-Produced Ionization Front

    SciTech Connect

    Higashiguchi, Takeshi; Hasegawa, Hideyuki; Nishimai, Hirofumi; Yugami, Noboru; Muggli, Patric

    2009-01-22

    We report the generation of radiation in the terahertz (THz) spectral region from an electrostatic field converted by a laser-produced relativistic ionization front. The THz radiation is generated through spatiotemporal change in electron density induced by a relativistic ionization front propagating in a ZnSe crystal enclosed in a capacitor array. The measured central radiation frequency is 1.2 THz with a bandwidth of 0.7 THz (FWHM), which is attributed to production of an electron density of the order of 10{sup 15} cm{sup -3}. The amplitude of the linearly polarized THz radiation increased linearly with the voltage applied to the capacitors.

  14. An analytical model for the calculation of the change in transmembrane potential produced by an ultrawideband electromagnetic pulse.

    PubMed

    Hart, Francis X; Easterly, Clay E

    2004-05-01

    The electric field pulse shape and change in transmembrane potential produced at various points within a sphere by an intense, ultrawideband pulse are calculated in a four stage, analytical procedure. Spheres of two sizes are used to represent the head of a human and the head of a rat. In the first stage, the pulse is decomposed into its Fourier components. In the second stage, Mie scattering analysis (MSA) is performed for a particular point in the sphere on each of the Fourier components, and the resulting electric field pulse shape is obtained for that point. In the third stage, the long wavelength approximation (LWA) is used to obtain the change in transmembrane potential in a cell at that point. In the final stage, an energy analysis is performed. These calculations are performed at 45 points within each sphere. Large electric fields and transmembrane potential changes on the order of a millivolt are produced within the brain, but on a time scale on the order of nanoseconds. The pulse shape within the brain differs considerably from that of the incident pulse. Comparison of the results for spheres of different sizes indicates that scaling of such pulses across species is complicated. PMID:15114634

  15. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    NASA Astrophysics Data System (ADS)

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-01

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  16. Guiding of Laser Beams in Plasmas by Radiation Cascade Compression

    SciTech Connect

    Kalmykov, Serguei; Shvets, Gennady

    2006-11-27

    The near-resonant heatwave excitation of an electron plasma wave (EPW) can be employed for generating trains of few-fs electromagnetic pulses in rarefied plasmas. The EPW produces a co-moving index grating that induces a laser phase modulation at the beat frequency. Consequently, the cascade of sidebands red- and blue-shifted from the fundamental by integer multiples of the beat frequency is generated in the laser spectrum. When the beat frequency is lower than the electron plasma frequency, the phase chirp enables laser beatnote compression by the group velocity dispersion [S. Kalmykov and G. Shvets, Phys. Rev. E 73, 046403 (2006)]. In the 3D cylindrical geometry, the frequency-downshifted EPW not only modulates the laser frequency, but also causes the pulse to self-focus [P. Gibbon, Phys. Fluids B 2, 2196 (1990)]. After self-focusing, the multi-frequency laser beam inevitably diverges. Remarkably, the longitudinal beatnote compression can compensate the intensity drop due to diffraction. A train of high-intensity radiation spikes with continually evolving longitudinal profile can be self-guided over several Rayleigh lengths in homogeneous plasmas. High amplitude of the EPW is maintained over the entire propagation length. Numerical experiments on the electron acceleration in the cascade-driven (cascade-guided) EPW [using the code WAKE by P. Mora and T. M. Antonsen Jr., Phys. Plasmas 4, 217 (1997)] show that achieving GeV electron energy is possible under realistic experimental parameters.

  17. Cascaded Gamma Rays as a Probe of Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Murase, Kohta

    2014-06-01

    Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

  18. Cascade Harvest’ red raspberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cascade Harvest’ is a new floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). ‘Cascade Harvest’ produces a high yield of large, firm fruit suited to machine harves...

  19. Cascaded target normal sheath acceleration

    SciTech Connect

    Wang, W. P.; Shen, B. F.; Zhang, X. M.; Wang, X. F.; Xu, J. C.; Zhao, X. Y.; Yu, Y. H.; Yi, L. Q.; Shi, Y.; Zhang, L. G.; Xu, T. J.; Xu, Z. Z.

    2013-11-15

    A cascaded target normal sheath acceleration (TNSA) scheme is proposed to simultaneously increase energy and improve energy spread of a laser-produced mono-energetic proton beam. An optimum condition that uses the maximum sheath field to accelerate the center of the proton beam is theoretically found and verified by two-dimensional particle-in-cell simulations. An initial 10 MeV proton beam is accelerated to 21 MeV with energy spread decreased from 5% to 2% under the optimum condition during the process of the cascaded TNSA. The scheme opens a way to scale proton energy lineally with laser energy.

  20. Generation of quantum electrodynamic cascades by colliding laser pulses

    NASA Astrophysics Data System (ADS)

    Gelfer, E. G.

    2016-04-01

    Quantum electrodynamic cascades in intense electromagnetic fields arise when the proper electron acceleration χ, expressed in Compton units, can attain values greater than or on the order of unity. For times t ll 1/ω, where ω is the carrier frequency of the field, we have derived a general formula for χ of an initially resting electron in an arbitrary electromagnetic field. Using this formula, we have found an optimal configuration of colliding laser pulses, which provides a significant reduction in the threshold intensity of occurrence of cascades up to a level of ~1023 W cm-2.

  1. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  2. Anomalous correlation between hadron and electromagnetic particles in hadron and gamma-ray families

    NASA Technical Reports Server (NTRS)

    Tamada, M.

    1985-01-01

    Correlations between hadrons and electromagnetic particles were studied in the hadron-gamma families observed in the Chacaltaya emulsion chamber experiment. It is found that there exist a number of hadrons which associate electromagnetic showers in extraordinarily close vicinity. The probability to have such a large number of hadrons associating electromagnetic showers, expected from background calculation, is found to be negligibly small and it means there exists anomalous correlation between hadrons and electromagnetic particles in the characteristic spread of atmospheric electromagnetic cascade.

  3. Interband cascade lasers

    NASA Astrophysics Data System (ADS)

    Vurgaftman, I.; Weih, R.; Kamp, M.; Meyer, J. R.; Canedy, C. L.; Kim, C. S.; Kim, M.; Bewley, W. W.; Merritt, C. D.; Abell, J.; Höfling, S.

    2015-04-01

    We review the current status of interband cascade lasers (ICLs) emitting in the midwave infrared (IR). The ICL may be considered the hybrid of a conventional diode laser that generates photons via electron-hole recombination, and an intersubband-based quantum cascade laser (QCL) that stacks multiple stages for enhanced current efficiency. Following a brief historical overview, we discuss theoretical aspects of the active region and core designs, growth by molecular beam epitaxy, and the processing of broad-area, narrow-ridge, and distributed feedback (DFB) devices. We then review the experimental performance of pulsed broad area ICLs, as well as the continuous-wave (cw) characteristics of narrow ridges having good beam quality and DFBs producing output in a single spectral mode. Because the threshold drive powers are far lower than those of QCLs throughout the λ = 3-6 µm spectral band, ICLs are increasingly viewed as the laser of choice for mid-IR laser spectroscopy applications that do not require high output power but need to be hand-portable and/or battery operated. Demonstrated ICL performance characteristics to date include threshold current densities as low as 106 A cm-2 at room temperature (RT), cw threshold drive powers as low as 29 mW at RT, maximum cw operating temperatures as high as 118 °C, maximum cw output powers exceeding 400 mW at RT, maximum cw wallplug efficiencies as high as 18% at RT, maximum cw single-mode output powers as high as 55 mW at RT, and single-mode output at λ = 5.2 µm with a cw drive power of only 138 mW at RT.

  4. South Cascade Glacier bibliography

    SciTech Connect

    Fountain, A.G.; Fulk, M.A.

    1984-01-01

    South Cascade Glacier, in Washington State, resides in a well-defined basin with mainly unglacierized divides making it ideal for most glaciological and hydrological studies. This bibliography is divided into three cateogories: (1) studies done about South Cascade Glacier specifically; (2) studies that use data from South Cascade Glacier but do not focus on or give insight to the glacier itself; and (3) instrumentation studies and non-glacier projects including snow studies done in the basin. (ACR)

  5. Thermally cascaded thermoelectric generator

    NASA Technical Reports Server (NTRS)

    Flaherty, R.

    1970-01-01

    High efficiency thermoelectric generator utilizes a high-temperature thermoelectric material in thermal series with a low-temperature material. A thermally cascaded generator increases system efficiency.

  6. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  7. Cascaded automatic target recognition (Cascaded ATR)

    NASA Astrophysics Data System (ADS)

    Walls, Bradley

    2010-04-01

    The global war on terror has plunged US and coalition forces into a battle space requiring the continuous adaptation of tactics and technologies to cope with an elusive enemy. As a result, technologies that enhance the intelligence, surveillance, and reconnaissance (ISR) mission making the warfighter more effective are experiencing increased interest. In this paper we show how a new generation of smart cameras built around foveated sensing makes possible a powerful ISR technique termed Cascaded ATR. Foveated sensing is an innovative optical concept in which a single aperture captures two distinct fields of view. In Cascaded ATR, foveated sensing is used to provide a coarse resolution, persistent surveillance, wide field of view (WFOV) detector to accomplish detection level perception. At the same time, within the foveated sensor, these detection locations are passed as a cue to a steerable, high fidelity, narrow field of view (NFOV) detector to perform recognition level perception. Two new ISR mission scenarios, utilizing Cascaded ATR, are proposed.

  8. Numerical Investigation of a Cascaded Longitudinal Space-Charge Amplifier at the Fermilab's Advanced Superconducting Test Accelerator

    SciTech Connect

    Halavanau, A.; Piot, P.

    2015-06-01

    In a cascaded longitudinal space-charge amplifier (LSCA), initial density noise in a relativistic e-beam is amplified via the interplay of longitudinal space charge forces and properly located dispersive sections. This type of amplification process was shown to potentially result in large final density modulations [1] compatible with the production of broadband electromagnetic radiation. The technique was recently demonstrated in the optical domain [2]. In this paper we investigate, via numerical simulations, the performances of a cascaded LSCA beamline at the Fermilab’s Advanced Superconducting Test Accelerator (ASTA). We especially explore the properties of the produced broadband radiation. Our studies have been conducted with a grid-less three-dimensional space-charge algorithm.

  9. Theory of cascade refrigeration

    NASA Astrophysics Data System (ADS)

    Quack, Hans H.

    2012-06-01

    The maximum difference between the warm and cold temperature of a refrigeration cycle is limited by properties of the refrigerant and/or losses associated with the transport of the refrigerant. For larger temperature differences, one has to arrange several refrigeration cycles "above" each other, each cycle spanning a certain temperature difference. This approach is called cascade refrigeration and has played an important role in the history of cryogenics. For a theory of cascade refrigeration it is helpful to define a general one-stage non-reversible refrigeration step and to visualize it within the temperature-entropy diagram. Then one can combine several one-stage cycles to a cascade. There exist two types of cascades: "Full" cascades, where all entropy gains of a lower stage are transferred to the next higher temperature stage, and "partial" cascades, where each single cycle goes up to ambient temperature, where a part of the entropy gain is removed, and only the rest of the entropy gain is transferred to the next higher temperature stage. In cryogenic refrigeration "partial" cascades are generally more efficient than "full" cascades.

  10. Electromagnetic fasteners

    SciTech Connect

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  11. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  12. HELIUM EFFECTS ON DISPLACEMENT CASCADE IN TUNGSTEN

    SciTech Connect

    Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.; Heinisch, Howard L.; Kurtz, Richard J.; Wirth, Brian D.

    2013-09-30

    Molecular dynamics (MD) simulations were performed to investigate He effects on displacement cascades in W. Helium content, proportion of interstitial and substitutional He and temperature were varied to reveal the various effects. The effect of interstitial He on the number of self-interstitial atoms (SIAs) produced during cascade damage appears to be insignificant. However, interstitial He tends to fill a vacancy (V). Nevertheless, this process is less favorable than SIA-V recombination particularly when excess SIAs are present before a cascade. The efficiency of He filling and SIA-V recombination increases as temperature increases due to increased point defect mobility. Likewise, substitutional He is more susceptible to displacement during a collision cascade than W. This susceptibility increases towards higher temperatures. Consequently, the number of surviving V is governed by the interplay between displaced substitutional He and SIA-V recombination. The temperature dependence of these processes results in a minimum number of V reached at an intermediate temperature.

  13. Superconductive electromagnet apparatus

    SciTech Connect

    Mine, S.

    1982-12-14

    Disclosed is a superconductive electromagnet apparatus having a coil with a coiled conductor with a channel between adjacently disposed the paths of the coil conductor of which width is selected in accordance with amounts of heat produced at the corresponding portions of the coil section as viewed in cross section.

  14. The CMS Electromagnetic Calorimeter

    SciTech Connect

    Paramatti, Riccardo

    2005-10-12

    The electromagnetic calorimeter of the CMS experiment at LHC will consist of about 76000 Lead Tungstate crystals. Its main purpose is the very precise energy measurement of electrons and photons produced at 14 TeV centre-of-mass energy. A review of its performances and its construction status is given. Then the calibration strategy is described in details.

  15. Electromagnetic Fields

    MedlinePlus

    ... cancer. Some people worry that wireless and cellular phones cause cancer. They give off radio-frequency energy (RF), a form of electromagnetic radiation. Scientists need to do more research on this ...

  16. Simultaneous Observation of Energy and Enstrophy Cascades in Thin-Layer Turbulence

    NASA Astrophysics Data System (ADS)

    Xia, Hua; Francois, Nicolas; Punzmann, Horst; Byrne, David; Shats, Michael

    2016-06-01

    We report the simultaneous observation of the inverse energy and direct enstrophy cascade in thin-layer turbulence. The experiments are conducted in an electromagnetically driven flow with layers of stratified fluid. Recent questions regarding the two-dimensionality of electromagnetically driven turbulence in such experiments are addressed.

  17. Binary black holes' effects on electromagnetic fields.

    PubMed

    Palenzuela, Carlos; Anderson, Matthew; Lehner, Luis; Liebling, Steven L; Neilsen, David

    2009-08-21

    In addition to producing gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We here study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as a possible enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves. PMID:19792706

  18. 5. VIEW OF UPPER AND LOWER CASCADE BRIDGES AND CASCADE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW OF UPPER AND LOWER CASCADE BRIDGES AND CASCADE CREEK FROM 100 YARDS WEST OF THE ROSTRUM (ROCK FORMATION ON SOUTH SIDE OF MERCED RIVER). HIGHWAY 140 IS AT BOTTOM OF FRAME. HIGHWAY 120, THE BIG OAK FLAT ROAD CROSSES FRAME JUST ABOVE CENTER. - Cascade Creek Bridge, Spanning Cascade Creek on New Big Oak Flat Road, Yosemite Village, Mariposa County, CA

  19. Cascades of Fano resonances in Mie scattering

    NASA Astrophysics Data System (ADS)

    Rybin, M. V.; Sinev, I. S.; Samusev, K. B.; Limonov, M. F.

    2014-03-01

    The interference nature of resonant Mie scattering, which is described within the Fano model, has been demonstrated. The interference is caused by interaction of an incident electromagnetic wave with reemitted waves that correspond to eigenmodes of a scattering particle. Mie scattering due to the interference can be represented in the form of cascades of resonance lines of different shapes, each of which is described by the classical Fano formula. The effect is observed in resonant light scattering by an arbitrary body of revolution and discussed in detail using the example of scattering by an infinite homogeneous dielectric cylinder.

  20. Unsteady Euler cascade analysis

    NASA Technical Reports Server (NTRS)

    Liu, Jong-Shang; Sockol, Peter M.

    1989-01-01

    The results of an investigation of the rotor-stator interaction phenomena in turbomachines are presented. Numerical study was carried out by solving the unsteady Euler equations in the blade-to-blade direction for a variety of cascade geometries. The problem of uneven rotor and stator blades is addressed by adopting the tilted time domain technique. Computed solutions are presented and discussed for a NACA 0012 type cascade and the first stage fuel turbopump of the Space Shuttle Main Engine (SSME).

  1. The nitrogen cascade

    SciTech Connect

    Galloway J.N.; Aber J.D.; Erisman J.W.; Seitzinger S.P.; Howarth R.W.; Cowling E.B.; Cosby B.J.

    2003-04-01

    Human production of food and energy is the dominant continental process that breaks the triple bond in molecular nitrogen (N{sub 2}) and creates reactive nitrogen (Nr) species. Circulation of anthropogenic Nr in Earth's atmosphere, hydrosphere, and biosphere has a wide variety of consequences, which are magnified with time as Nr moves along its biogeochemical pathway. The same atom of Nr can cause multiple effects in the atmosphere, in terrestrial ecosystems, in freshwater and marine systems, and on human health. We call this sequence of effects the nitrogen cascade. As the cascade progresses, the origin of Nr becomes unimportant. Reactive nitrogen does not cascade at the same rate through all environmental systems; some systems have the ability to accumulate Nr, which leads to lag times in the continuation of the cascade. These lags slow the cascade and result in Nr accumulation in certain reservoirs, which in turn can enhance the effects of Nr on that environment. The only way to eliminate Nr accumulation and stop the cascade is to convert Nr back to nonreactive N{sub 2}.

  2. Geothermal systems of the Cascade Range

    USGS Publications Warehouse

    Muffler, L.J.; Bacon, Charles R.; Duffield, W.A.

    1982-01-01

    In the central and southern Cascade Range, plate convergence is oblique, and Quaternary volcanism produces mostly basalt and mafic andesite; large andesite-dacite composite volcanoes and silicic dome fields occur in restricted areas of long-lived igneous activity. To the north, plate convergence is normal, producing widely spaced centers in which mafic lavas are minor. Most Cascade volcanoes are short-lived and unlikely to be underlain at shallow levels by large magma bodies that could support high-temperature geothermal systems. Such systems are known, however, near Meager Mountain, at Newberry Volcano, and near Lassen Peak. Persistent fumaroles occur on several major composite volcanoes, but drilling to date has been insufficient to determine whether exploitable geothermal reservoirs occur at depth. Thermal springs away from the major volcanic centers are few and generally inconspicuous. However, significant geothermal systems along and west of the Cascade Range may well be masked by abundant cold ground water.

  3. Electromagnetic Propulsion

    NASA Technical Reports Server (NTRS)

    Schafer, Charles

    2000-01-01

    The design and development of an Electromagnetic Propulsion is discussed. Specific Electromagnetic Propulsion Topics discussed include: (1) Technology for Pulse Inductive Thruster (PIT), to design, develop, and test of a multirepetition rate pulsed inductive thruster, Solid-State Switch Technology, and Pulse Driver Network and Architecture; (2) Flight Weight Magnet Survey, to determine/develop light weight high performance magnetic materials for potential application Advanced Space Flight Systems as these systems develop; and (3) Magnetic Flux Compression, to enable rapid/robust/reliable omni-planetary space transportation within realistic development and operational costs constraints.

  4. Electromagnetic effects - From cell biology to medicine.

    PubMed

    Funk, Richard H W; Monsees, Thomas; Ozkucur, Nurdan

    2009-01-01

    In this review we compile and discuss the published plethora of cell biological effects which are ascribed to electric fields (EF), magnetic fields (MF) and electromagnetic fields (EMF). In recent years, a change in paradigm took place concerning the endogenously produced static EF of cells and tissues. Here, modern molecular biology could link the action of ion transporters and ion channels to the "electric" action of cells and tissues. Also, sensing of these mainly EF could be demonstrated in studies of cell migration and wound healing. The triggers exerted by ion concentrations and concomitant electric field gradients have been traced along signaling cascades till gene expression changes in the nucleus. Far more enigmatic is the way of action of static MF which come in most cases from outside (e.g. earth magnetic field). All systems in an organism from the molecular to the organ level are more or less in motion. Thus, in living tissue we mostly find alternating fields as well as combination of EF and MF normally in the range of extremely low-frequency EMF. Because a bewildering array of model systems and clinical devices exits in the EMF field we concentrate on cell biological findings and look for basic principles in the EF, MF and EMF action. As an outlook for future research topics, this review tries to link areas of EF, MF and EMF research to thermodynamics and quantum physics, approaches that will produce novel insights into cell biology. PMID:19167986

  5. Stability of Helium Clusters during Displacement Cascades

    SciTech Connect

    Yang, Li; Zu, Xiaotao T.; Xiao, H. Y.; Gao, Fei; Heinisch, Howard L.; Kurtz, Richard J.; Wang, Zhiguo; Liu, K. Z.

    2007-02-01

    The interaction of displacement cascades with helium-vacancy clusters is investigated using molecular dynamics simulations. The He-vacancy clusters initially consist of 20 vacancies with a Helium-to-vacancy ratio ranging from 0.2 to 3. The primary knock-on atom (PKA) energy, Ep, varies from 2 keV to 10 keV, and the PKA direction is chosen such that a displacement cascade is able to directly interact with a helium-vacancy cluster. The simulation results show that the effect of displacement cascades on a helium-vacancy cluster strongly depends on both the helium-to-vacancy ratio and the PKA energy. For the same PKA energy, the size of helium-vacancy clusters increases with the He/V ratio, but for the same ratio, the cluster size changes more significantly with increasing PKA energy. It has been observed that the He-vacancy clusters can be dissolved when the He/V ratio less than 1, but they are able to re-nucleate during the thermal spike phase, forming small He-V nuclei. When the He/V ratio is larger than 1, the He-V clusters can absorb a number of vacancies produced by displacement cascades, forming larger He-V clusters. These results are discussed in terms of PKA energy, helium-to-vacancy ratio, number of vacancies produced by cascades, and mobility of helium atoms.

  6. Tracking Earthquake Cascades

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.

    2011-12-01

    In assessing their risk to society, earthquakes are best characterized as cascades that can propagate from the natural environment into the socio-economic (built) environment. Strong earthquakes rarely occur as isolated events; they usually cluster in foreshock-mainshock-aftershock sequences, seismic swarms, and extended sequences of large earthquakes that propagate along major fault systems. These cascades are regulated by stress-mediated interactions among faults driven by tectonic loading. Within these cascades, each large event can itself cause a chain reaction in which the primary effects of faulting and ground shaking induce secondary effects, including tsunami, landslides, liquefaction, and set off destructive processes within the built environment, such as fires and radiation leakage from nuclear plants. Recent earthquakes have demonstrated how the socio-economic effects of large earthquakes can reverberate for many years. To reduce earthquake risk and improve the resiliency of communities to earthquake damage, society depends on five geotechnologies for tracking earthquake cascades: long-term probabilistic seismic hazard analysis (PSHA), short-term (operational) earthquake forecasting, earthquake early warning, tsunami warning, and the rapid production of post-event information for response and recovery (see figure). In this presentation, I describe how recent advances in earthquake system science are leading to improvements in this geotechnology pipeline. In particular, I will highlight the role of earthquake simulations in predicting strong ground motions and their secondary effects before and during earthquake cascades

  7. Habitat cascades: the conceptual context and global relevance of facilitation cascades via habitat formation and modification.

    PubMed

    Thomsen, Mads S; Wernberg, Thomas; Altieri, Andrew; Tuya, Fernando; Gulbransen, Dana; McGlathery, Karen J; Holmer, Marianne; Silliman, Brian R

    2010-08-01

    The importance of positive interactions is increasingly acknowledged in contemporary ecology. Most research has focused on direct positive effects of one species on another. However, there is recent evidence that indirect positive effects in the form of facilitation cascades can also structure species abundances and biodiversity. Here we conceptualize a specific type of facilitation cascade-the habitat cascade. The habitat cascade is defined as indirect positive effects on focal organisms mediated by successive facilitation in the form of biogenic formation or modification of habitat. Based on a literature review, we demonstrate that habitat cascades are a general phenomenon that enhances species abundance and diversity in forests, salt marshes, seagrass meadows, and seaweed beds. Habitat cascades are characterized by a hierarchy of facilitative interactions in which a basal habitat former (typically a large primary producer, e.g., a tree) creates living space for an intermediate habitat former (e.g., an epiphyte) that in turn creates living space for the focal organisms (e.g., spiders, beetles, and mites). We then present new data on a habitat cascade common to soft-bottom estuaries in which a relatively small invertebrate provides basal habitat for larger intermediate seaweeds that, in turn, generate habitat for focal invertebrates and epiphytes. We propose that indirect positive effects on focal organisms will be strongest when the intermediate habitat former is larger and different in form and function from the basal habitat former. We also discuss how humans create, modify, and destroy habitat cascades via global habitat destruction, climatic change, over-harvesting, pollution, or transfer of invasive species. Finally, we outline future directions for research that will lead to a better understanding of habitat cascades. PMID:21558196

  8. Thin sheet casting with electromagnetic pressurization

    DOEpatents

    Walk, Steven R.; Slepian, R. Michael; Nathenson, Richard D.; Williams, Robert S.

    1991-01-01

    An apparatus, method and system for the casting of thin strips or strips of metal upon a moving chill block that includes an electromagnet located so that molten metal poured from a reservoir onto the chill block passes into the magnetic field produced by the electromagnet. The electromagnet produces a force on the molten metal on said chill block in the direction toward said chill block in order to enhance thermal contact between the molten metal and the chill block.

  9. Electromagnetic targeting of guns

    SciTech Connect

    Pogue, E.W.; Boat, R.M.; Holden, D.N.; Lopez, J.R.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.

  10. Resonant Cascaded Downconversion

    SciTech Connect

    Weedbrook, Christian; Parrett, Ben; Kheruntsyan, Karen; Drummond, Peter; Pooser, Raphael C; Pfister, Olivier

    2012-01-01

    We analyze an optical parametric oscillator (OPO) in which cascaded down-conversion occurs inside a cavity resonant for all modes but the initial pump. Due to the resonant cascade design, the OPO presents two {chi}{sup (2)}-level oscillation thresholds that are therefore much lower than for a {chi}{sup (3)} OPO. This is promising for reaching the regime of an effective third-order nonlinearity well above both thresholds. Such a {chi}{sup (2)} cascaded device also has potential applications in frequency conversion to far-infrared regimes. But, most importantly, it can generate novel multipartite quantum correlations in the output radiation, which represent a step beyond squeezed or entangled light. The output can be highly non-Gaussian and therefore not describable by any semiclassical model. In this paper, we derive quantum stochastic equations in the positive-P representation and undertake an analysis of steady-state and dynamical properties of this system.

  11. The dynamics of two-dimensional turbulence excited at two scales using electromagnetic forces

    NASA Astrophysics Data System (ADS)

    Habchi, Charbel; Antar, Ghassan

    2016-05-01

    Several forcing scales can co-exist in nature leading and affecting turbulent flows. This is not critical in three-dimensional systems where only a direct cascade of energy exists, but it is a concern in two dimensions where the direct and inverse cascades lead to different statistical properties of turbulence. The effect of forcing at two different scales on turbulence is studied here using numerical simulation inspired by a recent experiment [L. M. Moubarak and G. Y. Antar, "Dynamics of a two-dimensional flow subject to steady electromagnetic forces," Exp. Fluids 53, 1627-1636 (2012)] where a thin layer of electrolyte is stirred using electromagnetic forces. The small scale eddies are generated by the Lorentz force near the domain edge while the large scale motion is produced by the magnetic field gradient. We compare the case of one to two forcing scales for steady state turbulence to show that the addition of two forcing scales leads to the onset of turbulence at low Reynolds numbers due to the co-existence and thus the interaction of small and large structures. By determining the k-spectra as well as the energy transfer function, it is established that the dynamics of turbulence change from being dominated by an inverse cascade process, with one forcing scale, to one dominated by a direct cascade process when two scales are present. We believe that these results are important in understanding two- and quasi-two-dimensional turbulence phenomena occurring in nature where several excitation scales co-exist.

  12. Collisional Cascades Revisited

    NASA Astrophysics Data System (ADS)

    Schlichting, Hilke; Pan, M.

    2013-01-01

    Collisional cascades are believed to be the primary mechanism operating in circumstellar dusty debris disks, and are thought to be important in the Kuiper and Asteroid belt. Collisional cascades transfer mass via destructive collisions from larger bodies to smaller ones. Their widespread occurrence and potential importance in understanding planet formation and planet-disk interactions have motivated detailed studies of collisional cascades. The standard theoretical treatment of collisional cascades derives a steady-state size distribution assuming a single constant velocity dispersion for all bodies regardless of size. We relax this assumption and solve self-consistently for the bodies' steady-state size and size-dependent velocity distributions. Specifically, we account for viscous stirring, dynamical friction, and collisional damping of the bodies' random velocities in addition to the mass conservation requirement typically applied to find the size distribution in a steady-state cascade. The resulting size distributions are significantly steeper than those derived without velocity evolution. For example, accounting self-consistently for the velocities can change the standard q = 3.5 power-law index of the Dohnanyi differential size spectrum to an index as large as q = 4. Similarly, for bodies held together by their own gravity, the corresponding power-law index range 2.88 < q < 3.14 of Pan & Sari (2005) can steepen to values as large as q = 3.26. These differences in the size distribution power law index are very important when estimating the total disk mass, including larger bodies, by extrapolating from the observed dust masses. Our velocity results allow quantitative predictions of the bodies' scale heights as a function of size. Together with our predictions, observations of the scale heights for different-sized bodies in, for example, extrasolar debris disks may constrain the total mass in large bodies stirring the cascade as well as the colliding bodies

  13. Electromagnetic Hammer for Metalworking

    NASA Technical Reports Server (NTRS)

    Anderson, S. A.; Brunet, F.; Dowd, A.; Durham, R.; Ezell, J.; Gorr, G.; Hartley, D.; Jackson, F.; Marchand, J.; Macfarlane, W.; Nameth, P.; Okelly, K.; Phillips, H.; Rollo, J.; Rupert, E.; Sykes, H.; Vitrano, E.; Woods, M.

    1986-01-01

    High eddy currents apply pressure for cold-forming. Coil housing constructed for mechanical strength to hold coil against magnetic force, to maintain electrical contact with coil ends, and to maintain insulation between coil turns. Drilled holes placed to facilitate release of bubbles during potting. In contrast with mechanical hammers, electromagnetic hammer requires no dynamic material contact with workpiece; consequently, produces almost no change in metal grain structure.

  14. Intra Nucleon Cascade Program

    Energy Science and Technology Software Center (ESTSC)

    1998-08-18

    The package consists of three programs ISABEL, EVA, and PACE-2. ISABEL and PACE-2 are part of the LAHET code. ISABEL is an intra-nucleon cascade program. The output cascades are used as directly as input files to the two evaporation programs EVA and PACE-2. EVA ignores the effect of the angular momentum of the excited nuclei on the deexcitation and also ignores the possibility of gamma emission as long as particle emission is energetically allowed. PACE-2more » takes full account of angular momentum effects including irast levels and gamma emission at all stages of the evaporation chain.« less

  15. Electromagnetic Reciprocity.

    SciTech Connect

    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 and now a

  16. Harmonic cascade FEL designs for LUX

    SciTech Connect

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  17. Fundamental Investigation of Circumferentially Varying Stator Cascades

    NASA Astrophysics Data System (ADS)

    Farnsworth, John A. N.

    2011-12-01

    The fundamentals of circumferentially varying stator cascades and their interactions with a downstream fixed pitch propeller were investigated experimentally utilizing multiple measurement techniques. The flow physics associated with the isolated circumferentially varying, or cyclic, stator cascade was studied in a wind tunnel environment through string tuft flow visualization, 2-D PIV, Stereoscopic PIV, and static surface pressure measurements. The coupled wake physics of the cyclic stator cascade with propeller were then investigated in a water tunnel using Stereo PIV. Finally, the global performance of components and the coupled system were quantified through force and moment measurements on the model in the water tunnel. A cyclic distribution of the stators' deflections resulted in non-axisymmetric distributions of the surface pressure and the flow field downstream of the stator array. In the model near wake the flow field is associated with secondary flow patterns in the form of coherent streamwise vortical structures that can be described by potential flow mechanisms. The collective pitch distribution of the stators produces a flow field that resembles a potential Rankine vortex, whereas the cyclic pitch distribution generates a flow pattern that can be described by a potential vortex pair in a cross flow. The stator distribution alone produces a significant side force that increases linearly with stator pitch amplitude. When a propeller is incorporated downstream from the cyclic cascade the side force from the stator cascade is reduced, but a small vertical force and pitching moment are created. The generation of these secondary forces and moments can be related to the redistribution of the tangential flow from the cyclic cascade into the axial direction by the retreating and advancing blade states of the fixed pitch propeller.

  18. Howling about Trophic Cascades

    ERIC Educational Resources Information Center

    Kowalewski, David

    2012-01-01

    Following evolutionary theory and an agriculture model, ecosystem research has stressed bottom-up dynamics, implying that top wild predators are epiphenomenal effects of more basic causes. As such, they are assumed expendable. A more modern co-evolutionary and wilderness approach--trophic cascades--instead suggests that top predators, whose…

  19. 'Cascade Gold' raspberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cascade Gold’ is a new gold fruited, floricane fruiting raspberry cultivar (Rubus idaeus L.) jointly released by Washington State University (WSU), Oregon State University (OSU) and the U.S. Department of Agriculture (USDA). It has been evaluated at Puyallup, Wash. in plantings from 1988 to 2008. ...

  20. Cascaded thermoacoustic devices

    DOEpatents

    Swift, Gregory W.; Backhaus, Scott N.; Gardner, David L.

    2003-12-09

    A thermoacoustic device is formed with a resonator system defining at least one region of high specific acoustic impedance in an acoustic wave within the resonator system. A plurality of thermoacoustic units are cascaded together within the region of high specific acoustic impedance, where at least one of the thermoacoustic units is a regenerator unit.

  1. Search for acoustic signals from high energy cascades

    NASA Technical Reports Server (NTRS)

    Bell, R.; Bowen, T.

    1985-01-01

    High energy cosmic ray secondaries can be detected by means of the cascades they produce when they pass through matter. When the charged particles of these cascades ionize the matter they are traveling through, the heat produced and resulting thermal expansion causes a thermoacoustic wave. These sound waves travel at about one hundred-thousandth the speed of light, and should allow an array of acoustic transducers to resolve structure in the cascade to about 1 cm without high speed electronics or segmentation of the detector.

  2. Integrated Broadband Quantum Cascade Laser

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou (Inventor); Soibel, Alexander (Inventor)

    2016-01-01

    A broadband, integrated quantum cascade laser is disclosed, comprising ridge waveguide quantum cascade lasers formed by applying standard semiconductor process techniques to a monolithic structure of alternating layers of claddings and active region layers. The resulting ridge waveguide quantum cascade lasers may be individually controlled by independent voltage potentials, resulting in control of the overall spectrum of the integrated quantum cascade laser source. Other embodiments are described and claimed.

  3. Cascade decays of hollow ions

    SciTech Connect

    Omar, G. ); Hahn, Y. )

    1991-05-01

    A multiple-electron-emission process for atoms with one or more inner-shell vacancies is treated using the radiative- and Auger-electron-emission cascade model, in which inner-shell holes are assumed to decay by sequentially emitting radiations and/or Auger electrons. Such hollow ions are produced by synchrotron irradiation of atomic targets and in ion-surface interactions with multiple-electron transfers. The final charge-state distribution is determined by the Auger and radiative branching ratios at each stage of the decay sequence. At intermediate stages of cascade, hollow ions with more than one hole in different ionization stages are created. The Ne, Mg, and Fe{sup 14+} ions with the initial 1{ital s}, 2{ital s}, and 2{ital p} vacancies are considered in detail, and the core charge dependence of the maximum charge state is studied. The hollow Mg ion with double initial 1{ital s} holes is analyzed, and the result compared with that for the case of one 1{ital s} hole. The peak is shifted more than two units to a higher degree of ionization. The correlated shake-off and shake-up multiple-electron processes are not considered, but they are expected to cause further shifts.

  4. Lifespans of Cascade Arc volcanoes

    NASA Astrophysics Data System (ADS)

    Calvert, A. T.

    2015-12-01

    Compiled argon ages reveal inception, eruptive episodes, ages, and durations of Cascade stratovolcanoes and their ancestral predecessors. Geologic mapping and geochronology show that most Cascade volcanoes grew episodically on multiple scales with periods of elevated behavior lasting hundreds of years to ca. 100 kyr. Notable examples include the paleomag-constrained, few-hundred-year-long building of the entire 15-20 km3 Shastina edifice at Mt. Shasta, the 100 kyr-long episode that produced half of Mt. Rainier's output, and the 30 kyr-long episode responsible for all of South and Middle Sister. Despite significant differences in timing and rates of construction, total durations of active and ancestral volcanoes at discrete central-vent locations are similar. Glacier Peak, Mt. Rainier, Mt. Adams, Mt. Hood, and Mt. Mazama all have inception ages of 400-600 ka. Mt. St. Helens, Mt. Jefferson, Newberry Volcano, Mt. Shasta and Lassen Domefield have more recent inception ages of 200-300 ka. Only the Sisters cluster and Mt. Baker have established eruptive histories spanning less than 50 kyr. Ancestral volcanoes centered 5-20 km from active stratocones appear to have similar total durations (200-600 kyr), but are less well exposed and dated. The underlying mechanisms governing volcano lifecycles are cryptic, presumably involving tectonic and plumbing changes and perhaps circulation cycles in the mantle wedge, but are remarkably consistent along the arc.

  5. Energy flow in a hadronic cascade: Application to hadroncalorimetry

    SciTech Connect

    Groom, Donald E.

    2006-05-17

    The hadronic cascade description developed in an earlierpaper is extended to the response of an idealized fine-sampling hadroncalorimeter. Calorimeter response is largely determined by the transferof energy E_e from the hadronic to the electromagnetic sector via \\pi0production. Fluctuations in this quantity produce the "constant term" inhadron calorimeter resolution. The increase of its fractional mean, f_\\rmem^0= \\vevE_e/E, with increasing incident energy E causes the energydependence of the \\pi/e ratio in a noncompensating calorimeter. The meanhadronic energy fraction, f_h0 = 1-f_\\rm em0, was shown to scaleverynearly as a power law in E: f_h0 = (E/E_0)m-1, where E_0\\approx1~;GeV forpions, and m\\approx0.83. It follows that \\pi/e=1-(1-h/e)(E/E_0)m-1, whereelectromagnetic and hadronic energy deposits are detected withefficiencies e and h, respectively. Fluctuations in these quantities,along with sampling fluctuations, are in corporated to give an overallunderstanding of resolution, which is different from the usual treatmentsin interesting ways. The conceptual framework is also extended to theresponse to jets and the difference between pi and presponse.

  6. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  7. Anisotropic conducting films for electromagnetic radiation applications

    DOEpatents

    Cavallo, Francesca; Lagally, Max G.; Rojas-Delgado, Richard

    2015-06-16

    Electronic devices for the generation of electromagnetic radiation are provided. Also provided are methods for using the devices to generate electromagnetic radiation. The radiation sources include an anisotropic electrically conducting thin film that is characterized by a periodically varying charge carrier mobility in the plane of the film. The periodic variation in carrier mobility gives rise to a spatially varying electric field, which produces electromagnetic radiation as charged particles pass through the film.

  8. Superconducting cascade electron refrigerator

    SciTech Connect

    Camarasa-Gómez, M.; Giazotto, F.; Di Marco, A.; Hekking, F. W. J.; Winkelmann, C. B.; Courtois, H.

    2014-05-12

    The design and operation of an electronic cooler based on a combination of superconducting tunnel junctions is described. The cascade extraction of hot-quasiparticles, which stems from the energy gaps of two different superconductors, allows for a normal metal to be cooled down to about 100 mK starting from a bath temperature of 0.5 K. We discuss the practical implementation, potential performance, and limitations of such a device.

  9. Information cascade on networks

    NASA Astrophysics Data System (ADS)

    Hisakado, Masato; Mori, Shintaro

    2016-05-01

    In this paper, we discuss a voting model by considering three different kinds of networks: a random graph, the Barabási-Albert (BA) model, and a fitness model. A voting model represents the way in which public perceptions are conveyed to voters. Our voting model is constructed by using two types of voters-herders and independents-and two candidates. Independents conduct voting based on their fundamental values; on the other hand, herders base their voting on the number of previous votes. Hence, herders vote for the majority candidates and obtain information relating to previous votes from their networks. We discuss the difference between the phases on which the networks depend. Two kinds of phase transitions, an information cascade transition and a super-normal transition, were identified. The first of these is a transition between a state in which most voters make the correct choices and a state in which most of them are wrong. The second is a transition of convergence speed. The information cascade transition prevails when herder effects are stronger than the super-normal transition. In the BA and fitness models, the critical point of the information cascade transition is the same as that of the random network model. However, the critical point of the super-normal transition disappears when these two models are used. In conclusion, the influence of networks is shown to only affect the convergence speed and not the information cascade transition. We are therefore able to conclude that the influence of hubs on voters' perceptions is limited.

  10. Superconducting cascade electron refrigerator

    NASA Astrophysics Data System (ADS)

    Camarasa-Gómez, M.; Di Marco, A.; Hekking, F. W. J.; Winkelmann, C. B.; Courtois, H.; Giazotto, F.

    2014-05-01

    The design and operation of an electronic cooler based on a combination of superconducting tunnel junctions is described. The cascade extraction of hot-quasiparticles, which stems from the energy gaps of two different superconductors, allows for a normal metal to be cooled down to about 100 mK starting from a bath temperature of 0.5 K. We discuss the practical implementation, potential performance, and limitations of such a device.

  11. RECONFIGURING POWER SYSTEMS TO MINIMIZE CASCADING FAILURES: MODELS AND ALGORITHMS

    SciTech Connect

    Bienstock, Daniel

    2014-04-11

    the main goal of this project was to develop new scientific tools, based on optimization techniques, with the purpose of controlling and modeling cascading failures of electrical power transmission systems. We have developed a high-quality tool for simulating cascading failures. The problem of how to control a cascade was addressed, with the aim of stopping the cascade with a minimum of load lost. Yet another aspect of cascade is the investigation of which events would trigger a cascade, or more appropriately the computation of the most harmful initiating event given some constraint on the severity of the event. One common feature of the cascade models described (indeed, of several of the cascade models found in the literature) is that we study thermally-induced line tripping. We have produced a study that accounts for exogenous randomness (e.g. wind and ambient temperature) that could affect the thermal behavior of a line, with a focus on controlling the power flow of the line while maintaining safe probability of line overload. This was done by means of a rigorous analysis of a stochastic version of the heat equation. we incorporated a model of randomness in the behavior of wind power output; again modeling an OPF-like problem that uses chance-constraints to maintain low probability of line overloads; this work has been continued so as to account for generator dynamics as well.

  12. Geothermal research, Oregon Cascades: Final technical report

    SciTech Connect

    Priest, G.R.; Black, G.L.

    1988-10-27

    Previous USDOE-funded geothermal studies have produced an extensive temperature gradient and heat flow data base for the State of Oregon. One of the important features identified as a result of these studies is a rapid transition from heat flow values on the order of 40 mW/m/sup 2/ in the Willamette Valley and Western Cascades to values of greater than or equal to100 mW/m/sup 2/ in the High Cascades and the eastern portion of the Western Cascades. These data indicate that the Cascade Range in Oregon has potential as a major geothermal province and stimulated much of the later work completed by government agencies and private industry. Additional data generated as a result of this grant and published in DOGAMI Open-File Report 0-86-2 further define the location and magnitude of this transition zone. In addition, abundant data collected from the vicinity of Breitenbush and Austin Hot Springs have permitted the formulation of relatively detailed models of these hydrothermal systems. These models are published in DOGAMI Open-File Report 0-88-5. Task 1.2 of the Deliverables section of Amendment M001 is fulfilled by DOGAMI publication GMS-48, Geologic map of the McKenzie Bridge quadrangle, Lane County, Oregon. This map was printed in October, 1988, and is part of the final submission to USDOE. 8 refs.

  13. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  14. Inverse cascades sustained by the transfer rate of angular momentum in a 3D turbulent flow.

    PubMed

    López-Caballero, Miguel; Burguete, Javier

    2013-03-22

    The existence of energy cascades as signatures of conserved magnitudes is one of the universal characteristics of turbulent flows. In homogeneous 3D turbulence, the energy conservation produces a direct cascade from large to small scales, although in 2D, it produces an inverse cascade pointing towards small wave numbers. In this Letter, we present the first evidence of an inverse cascade in a fully developed 3D experimental turbulent flow where the conserved magnitude is the angular momentum. Two counterrotating flows collide in a central region where very large fluctuations are produced, generating a turbulent drag that transfers the external torque between different fluid layers. PMID:25166809

  15. Electromagnetic topology - Characterization of internal electromagnetic coupling

    NASA Astrophysics Data System (ADS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    This paper presents the main principles 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 electromagnetic topology. 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.

  16. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Astrophysics Data System (ADS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-08-01

    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.

  17. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    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.

  18. The Ufm1 Cascade

    PubMed Central

    Daniel, Jens; Liebau, Eva

    2014-01-01

    The ubiquitin-fold modifier 1 (Ufm1) is a posttranslational modifier that belongs to the ubiquitin-like protein (UBL) family. Ufm1 is present in nearly all eukaryotic organisms, with the exception of fungi. It resembles ubiquitin in its ability to be ligated to other proteins, as well as in the mechanism of ligation. While the Ufm1 cascade has been implicated in endoplasmic reticulum functions and cell cycle control, its biological role still remains poorly understood. In this short review, we summarize the current state of Ufm1 research and its potential role in human diseases, like diabetes, ischemic heart disease and cancer. PMID:24921187

  19. The Influence of Plasma Effects of Pair Beams on the Intergalactic Cascade Emission of Blazars

    NASA Astrophysics Data System (ADS)

    Menzler, Ulf; Schlickeiser, Reinhard

    2014-03-01

    The attenuation of TeV γ-rays from distant blazars by the extragalactic background light (EBL) produces relativistic electron-positron pair beams. It has been shown by Broderick et. al. (2012) and Schlickeiser et. al (2012) that a pair beam traversing the intergalactic medium is unstable to linear two-stream instabilities of both electrostatic and electromagnetic nature. While for strong blazars all free pair energy is dissipated in heating the intergalactic medium and a potential electromagnetic cascade via inverse-Compton scattering with the cosmic microwave background is suppressed, we investigate the case of weak blazars where the back reaction of generated electrostatic turbulence leads to a plateauing of the electron energy spectrum. In the ultra-relativistic Thomson limit we analytically calculate the inverse-Compton spectral energy distribution for both an unplateaued and a plateaued beam scenario, showing a peak reduction factor of Rpeak ≈ 0.345. This is consistent with the FERMI non-measurements of a GeV excess in the spectrum of EBL attenuated TeV blazars. Claims on the lower bound of the intergalactic magnetic field strengths, made by several authors neglecting plasma effects, are thus put into question.

  20. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  1. Electromagnetic biostimulation of living cultures for biotechnology, biofuel and bioenergy applications.

    PubMed

    Hunt, Ryan W; Zavalin, Andrey; Bhatnagar, Ashish; Chinnasamy, Senthil; Das, Keshav C

    2009-10-01

    The surge of interest in bioenergy has been marked with increasing efforts in research and development to identify new sources of biomass and to incorporate cutting-edge biotechnology to improve efficiency and increase yields. It is evident that various microorganisms will play an integral role in the development of this newly emerging industry, such as yeast for ethanol and Escherichia coli for fine chemical fermentation. However, it appears that microalgae have become the most promising prospect for biomass production due to their ability to grow fast, produce large quantities of lipids, carbohydrates and proteins, thrive in poor quality waters, sequester and recycle carbon dioxide from industrial flue gases and remove pollutants from industrial, agricultural and municipal wastewaters. In an attempt to better understand and manipulate microorganisms for optimum production capacity, many researchers have investigated alternative methods for stimulating their growth and metabolic behavior. One such novel approach is the use of electromagnetic fields for the stimulation of growth and metabolic cascades and controlling biochemical pathways. An effort has been made in this review to consolidate the information on the current status of biostimulation research to enhance microbial growth and metabolism using electromagnetic fields. It summarizes information on the biostimulatory effects on growth and other biological processes to obtain insight regarding factors and dosages that lead to the stimulation and also what kind of processes have been reportedly affected. Diverse mechanistic theories and explanations for biological effects of electromagnetic fields on intra and extracellular environment have been discussed. The foundations of biophysical interactions such as bioelectromagnetic and biophotonic communication and organization within living systems are expounded with special consideration for spatiotemporal aspects of electromagnetic topology, leading to the

  2. Electromagnetic Biostimulation of Living Cultures for Biotechnology, Biofuel and Bioenergy Applications

    PubMed Central

    Hunt, Ryan W.; Zavalin, Andrey; Bhatnagar, Ashish; Chinnasamy, Senthil; Das, Keshav C.

    2009-01-01

    The surge of interest in bioenergy has been marked with increasing efforts in research and development to identify new sources of biomass and to incorporate cutting-edge biotechnology to improve efficiency and increase yields. It is evident that various microorganisms will play an integral role in the development of this newly emerging industry, such as yeast for ethanol and Escherichia coli for fine chemical fermentation. However, it appears that microalgae have become the most promising prospect for biomass production due to their ability to grow fast, produce large quantities of lipids, carbohydrates and proteins, thrive in poor quality waters, sequester and recycle carbon dioxide from industrial flue gases and remove pollutants from industrial, agricultural and municipal wastewaters. In an attempt to better understand and manipulate microorganisms for optimum production capacity, many researchers have investigated alternative methods for stimulating their growth and metabolic behavior. One such novel approach is the use of electromagnetic fields for the stimulation of growth and metabolic cascades and controlling biochemical pathways. An effort has been made in this review to consolidate the information on the current status of biostimulation research to enhance microbial growth and metabolism using electromagnetic fields. It summarizes information on the biostimulatory effects on growth and other biological processes to obtain insight regarding factors and dosages that lead to the stimulation and also what kind of processes have been reportedly affected. Diverse mechanistic theories and explanations for biological effects of electromagnetic fields on intra and extracellular environment have been discussed. The foundations of biophysical interactions such as bioelectromagnetic and biophotonic communication and organization within living systems are expounded with special consideration for spatiotemporal aspects of electromagnetic topology, leading to the

  3. Electromagnetically Induced Entanglement

    NASA Astrophysics Data System (ADS)

    Yang, Xihua; Xiao, Min

    2015-08-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing.

  4. Electromagnetically Induced Entanglement.

    PubMed

    Yang, Xihua; Xiao, Min

    2015-01-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing. PMID:26314514

  5. Serpentine Robot Arm Contains Electromagnetic Actuators

    NASA Technical Reports Server (NTRS)

    Moya, Israel A.; Studer, Philip A.

    1994-01-01

    Identical modules assembled into flexible robot arm configured in serpentlike fashion to manipulate objects while avoiding obstacles. Each module includes integral electromagnetic actuators energized selectively to produce variety of motions, stationary configurations, and combinations thereof.

  6. Electromagnetic Gun With Commutated Coils

    NASA Technical Reports Server (NTRS)

    Elliott, David G.

    1991-01-01

    Proposed electromagnetic gun includes electromagnet coil, turns of which commutated in sequence along barrel. Electrical current fed to two armatures by brushes sliding on bus bars in barrel. Interaction between armature currents and magnetic field from coil produces force accelerating armature, which in turn, pushes on projectile. Commutation scheme chosen so magnetic field approximately coincides and moves with cylindrical region defined by armatures. Scheme has disadvantage of complexity, but in return, enables designer to increase driving magnetic field without increasing armature current. Attainable muzzle velocity increased substantially.

  7. Pulsed power for electromagnetic launching

    NASA Astrophysics Data System (ADS)

    Cowan, M.

    1980-12-01

    There are system advantages to producing power for electromagnetic propulsion by real-time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  8. Pulsed power for electromagnetic launching

    NASA Astrophysics Data System (ADS)

    Cowan, M.

    1982-01-01

    There are system advantages to producing power for electromagnetic propulsion by real time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator. Different types of flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  9. Pulsed power for electromagnetic launching

    SciTech Connect

    Cowan, M

    1980-12-01

    There are system advantages to producing power for electromagnetic propulsion by real-time generation rather than by a sequence of generation-storage-switching. The best type of generator for this purpose is the flux compression generator. Different types of flux compression generator which have been developed at Sandia National Laboratories are reviewed and their applications to electric launching are discussed. New experimental facilities for producing more powerful generators are described and cost comparisons are made.

  10. The effects of self-interstitial clusters on cascade defect evolution beyond the primary damage state

    SciTech Connect

    Heinisch, H.L.

    1997-04-01

    The intracascade evolution of the defect distributions of cascades in copper is investigated using stochastic annealing simulations applied to cascades generated with molecular dynamics (MD). The temperature and energy dependencies of annihilation, clustering and free defect production are determined for individual cascades. The annealing simulation results illustrate the strong influence on intracascade evolution of the defect configuration existing in the primary damage state. Another factor significantly affecting the evolution of the defect distribution is the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. This phenomenon introduces a cascade energy dependence of defect evolution that is apparent only beyond the primary damage state, amplifying the need for further study of the annealing phase of cascade evolution and for performing many more MD cascade simulations at higher energies.

  11. Rapid fitting of particle cascade development data from X-ray film densitometry measurements

    NASA Technical Reports Server (NTRS)

    Roberts, E.; Benson, Carl M.; Fountain, Walter F.

    1989-01-01

    A semiautomatic method of fitting transition curves to X-ray film optical density measurements of electromagnetic particle cascades is described. Several hundred singly and multiple interacting cosmic ray events from the JACEE 8 balloon flights were analyzed using this procedure. In addition to greatly increased speed compared to the previous manual method, the semiautomatic method offers increased accuracy through maximum likelihood fitting.

  12. Cascade Error Projection Learning Algorithm

    NASA Technical Reports Server (NTRS)

    Duong, T. A.; Stubberud, A. R.; Daud, T.

    1995-01-01

    A detailed mathematical analysis is presented for a new learning algorithm termed cascade error projection (CEP) and a general learning frame work. This frame work can be used to obtain the cascade correlation learning algorithm by choosing a particular set of parameters.

  13. Cascade Distillation System Development

    NASA Technical Reports Server (NTRS)

    Callahan, Michael R.; Sargushingh, Miriam; Shull, Sarah

    2014-01-01

    NASA's Advanced Exploration Systems (AES) Life Support System (LSS) Project is chartered with de-veloping advanced life support systems that will ena-ble NASA human exploration beyond low Earth orbit (LEO). The goal of AES is to increase the affordabil-ity of long-duration life support missions, and to re-duce the risk associated with integrating and infusing new enabling technologies required to ensure mission success. Because of the robust nature of distillation systems, the AES LSS Project is pursuing develop-ment of the Cascade Distillation Subsystem (CDS) as part of its technology portfolio. Currently, the system is being developed into a flight forward Generation 2.0 design.

  14. Cascaded radiation pressure acceleration

    SciTech Connect

    Pei, Zhikun; Shen, Baifei E-mail: zhxm@siom.ac.cn; Zhang, Xiaomei E-mail: zhxm@siom.ac.cn; Wang, Wenpeng; Zhang, Lingang; Yi, Longqing; Shi, Yin; Xu, Zhizhan

    2015-07-15

    A cascaded radiation-pressure acceleration scheme is proposed. When an energetic proton beam is injected into an electrostatic field moving at light speed in a foil accelerated by light pressure, protons can be re-accelerated to much higher energy. An initial 3-GeV proton beam can be re-accelerated to 7 GeV while its energy spread is narrowed significantly, indicating a 4-GeV energy gain for one acceleration stage, as shown in one-dimensional simulations and analytical results. The validity of the method is further confirmed by two-dimensional simulations. This scheme provides a way to scale proton energy at the GeV level linearly with laser energy and is promising to obtain proton bunches at tens of gigaelectron-volts.

  15. Cascade Mtns. Oregon

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The ground near one of the long-dormant Three Sisters volcanoes in the Cascade Mountains of west-central Oregon has risen approximately 10centimeters in a 10-by-20-km parcel since 1996, meaning that magma or underground lava is slowly flowing into the area, according to a research team from the U.S. Geological Survey. The Three Sisters area -- which contains five volcanoes -- is only about 170 miles from Mount St. Helens, which erupted in 1980. Both are part of the Cascades Range, a line of 27volcanoes stretching from British Columbia in Canada to northern California. This perspective view was created by draping a simulated natural color ASTER image over digital topography from the U.S. Geological Survey National Elevation Dataset.

    This image was acquired on May 28, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical

  16. Using Airborne and Ground Electromagnetic Surveys and DC Resistivity Surveys to Delineate a Plume of Conductive Water at an In-Channel Coalbed Methane Produced Water Impoundment Near the Powder River, Wyoming

    NASA Astrophysics Data System (ADS)

    Lipinski, B. A.; Harbert, W.; Hammack, R.; Sams, J.; Veloski, G.; Smith, B. D.

    2004-12-01

    Development of coal bed methane (CBM) in the Powder River Basin of Wyoming and Montana has significantly increased since 1997. Production of CBM involves withdrawing groundwater from the coal bed to lower the hydrostatic pressure thereby allowing methane to desorb from the coal. The water co-produced with CBM is managed by storing it in impoundments until it can infiltrate to the groundwater, be used for beneficial purposes, or be discharged to surface streams. Skewed Reservoir was constructed as a research site to evaluate disposal of CBM water through infiltration ponds constructed by damming ephemeral streams. Geochemical data collected from monitoring wells placed downgradient of the reservoir detected a plume of water with total dissolved solids concentrations an order of magnitude higher than the CBM water stored in the impoundment. Infiltrating CBM water is suspected to have dissolved salts that were present in the unconsolidated materials beneath the reservoir. A geophysical investigation of the Skewed Reservoir area was conducted in July of 2004 to map the horizontal and vertical extent of the plume and to possibly identify the source of solutes to the infiltrating water. The Department of Energy's National Energy Technology Laboratory contracted Fugro Airborne Surveys to fly their RESOLVE frequency domain airborne electromagnetic (AEM) system with 50-m line spacing at the site. A ground investigation was completed at the same time as the airborne survey. Five 2-D dipole-dipole resistivity surveys and one 3-D pole-dipole survey were conducted using the AGI SuperSting R8/IP multi-channel resistivity imaging system. Additionally, ground conductivity measurements were recorded along each resistivity line using a Geophex GEM-2 multi-frequency ground conductivity meter. All geoelectrical measurements were inverted to obtain the subsurface conductivity distribution. Inversions were constrained using results of downhole borehole induction logs. Results were

  17. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  18. Cascading Effects Following Intervention

    PubMed Central

    Patterson, Gerald R.; Forgatch, Marion S.; DeGarmo, David S.

    2010-01-01

    Four different sources for cascade effects were examined using 9-year process and outcome data from a randomized controlled trial (RCT) of a preventive intervention using Parent Management Training – Oregon Model (PMTO™). The social interaction learning (SIL) model of child antisocial behavior serves as one basis for predicting change. A second source addresses the issue of comorbid relationships among clinical diagnoses. The third source, collateral changes, describes events in which changes in one family member correlate with changes in another. The fourth component is based on the long-term effects of reducing coercion and increasing positive interpersonal processes within the family. New findings from the 9-year follow-up show that mothers experienced benefits as measured by standard of living (i.e., income, occupation, education, and financial stress) and frequency of police arrests. It is assumed that PMTO reduces the level of coercion, which sets the stage for a massive increase in positive social interaction. In effect, PMTO alters the family environment and thereby opens doors to healthy new social environments. PMID:20883592

  19. Terahertz quantum cascade VECSEL

    NASA Astrophysics Data System (ADS)

    Xu, Luyao; Curwen, Christopher A.; Hon, Philip W. C.; Itoh, Tatsuo; Williams, Benjamin S.

    2016-03-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) have been successfully used in the visible and near-infrared to achieve high output power with excellent Gaussian beam quality. However, the concept of VECSEL has been impossible to implement for quantum-cascade (QC) lasers due to the "intersubband selection rule". We have recently demonstrated the first VECSEL in the terahertz range. The enabling component for the QC-VECSEL is an amplifying metasurface reflector composed of a sparse array of metallic sub-cavities, which allows the normally incident radiation to interact with the electrically pumped QC gain medium. In this work, we presented multiple design variations based on the first demonstrated THz QC-VECSEL, regarding the lasing frequencies, the output coupler and the intra-cavity aperture. Our work on THz QC-VECSEL initiates a new approach towards achieving scalable output power in combination with a diffraction-limited beam pattern for THz QC-lasers. The design variations presented in this work further demonstrate the practicality and potential of VECSEL approach to make ideal terahertz QC-laser sources.

  20. The electromagnetic spike solutions

    NASA Astrophysics Data System (ADS)

    Nungesser, Ernesto; Lim, Woei Chet

    2013-12-01

    The aim of this paper is to use the existing relation between polarized electromagnetic Gowdy spacetimes and vacuum Gowdy spacetimes to find explicit solutions for electromagnetic spikes by a procedure which has been developed by one of the authors for gravitational spikes. We present new inhomogeneous solutions which we call the EME and MEM electromagnetic spike solutions.

  1. Design of choking cascade turns

    NASA Astrophysics Data System (ADS)

    Baird, J.

    1982-12-01

    Five different shock-positioning cascades, for short-radius turns in ramjet inlet diffusers, were designed and tested on the AFIT water table. These flow controllers were to perform the same function as the conventional arrangement of an aerodynamic grid and a long-radius turn. The tests were to determine the suitability of the water table for such experimentation, in addition to determining the flow-control capabilities and pressure recovery of the cascades. All five designs accomplished the flow-control function as designed, and two designs exhibited the same or better pressure recovery than the aerodynamic grid. The water table proved to be an excellent means of testing these cascades, primarily due to the ease of flow visualization in the tests done. The shock-positioning cascade, short-radius turn concept shows promise and should be tested further in gas-dynamic apparatus.

  2. Cascade redox flow battery systems

    DOEpatents

    Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

    2014-07-22

    A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

  3. Stochastic background of atmospheric cascades

    NASA Astrophysics Data System (ADS)

    Wilk, G.; WŁOdarczyk, Z.

    1993-06-01

    Fluctuations in the atmospheric cascades developing during the propagation of very high energy cosmic rays through the atmosphere are investigated using stochastic branching model of pure birth process with immigration. In particular, we show that the multiplicity distributions of secondaries emerging from gamma families are much narrower than those resulting from hadronic families. We argue that the strong intermittent like behaviour found recently in atmospheric families results from the fluctuations in the cascades themselves and are insensitive to the details of elementary interactions.

  4. Computation of inverse magnetic cascades

    SciTech Connect

    Montgomery, D.

    1981-10-01

    Inverse cascades of magnetic quantities for turbulent incompressible magnetohydrodynamics are reviewed, for two and three dimensions. The theory is extended to the Strauss equations, a description intermediate between two and three dimensions appropriate to tokamak magnetofluids. Consideration of the absolute equilibrium Gibbs ensemble for the system leads to a prediction of an inverse cascade of magnetic helicity, which may manifest itself as a major disruption. An agenda for computational investigation of this conjecture is proposed.

  5. Stochastic background of atmospheric cascades

    SciTech Connect

    Wilk, G. ); Wlodarczyk, Z. )

    1993-06-15

    Fluctuations in the atmospheric cascades developing during the propagation of very high energy cosmic rays through the atmosphere are investigated using stochastic branching model of pure birth process with immigration. In particular, we show that the multiplicity distributions of secondaries emerging from gamma families are much narrower than those resulting from hadronic families. We argue that the strong intermittent like behaviour found recently in atmospheric families results from the fluctuations in the cascades themselves and are insensitive to the details of elementary interactions.

  6. Computation of inverse magnetic cascades

    NASA Technical Reports Server (NTRS)

    Montgomery, D.

    1981-01-01

    Inverse cascades of magnetic quantities for turbulent incompressible magnetohydrodynamics are reviewed, for two and three dimensions. The theory is extended to the Strauss equations, a description intermediate between two and three dimensions appropriate to Tokamak magnetofluids. Consideration of the absolute equilibrium Gibbs ensemble for the system leads to a prediction of an inverse cascade of magnetic helicity, which may manifest itself as a major disruption. An agenda for computational investigation of this conjecture is proposed.

  7. The cascade high productivity language

    NASA Technical Reports Server (NTRS)

    Callahan, David; Chamberlain, Branford L.; Zima, Hans P.

    2004-01-01

    This paper describes the design of Chapel, the Cascade High Productivity Language, which is being developed in the DARPA-funded HPCS project Cascade led by Cray Inc. Chapel pushes the state-of-the-art in languages for HEC system programming by focusing on productivity, in particular by combining the goal of highest possible object code performance with that of programmability offered by a high-level user interface.

  8. Cascading gravity is ghost free

    SciTech Connect

    Rham, Claudia de; Khoury, Justin; Tolley, Andrew J.

    2010-06-15

    We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.

  9. Cascaded proton acceleration by collisionless electrostatic shock

    SciTech Connect

    Xu, T. J.; Shen, B. F. E-mail: zhxm@siom.ac.cn; Zhang, X. M. E-mail: zhxm@siom.ac.cn; Yi, L. Q.; Wang, W. P.; Zhang, L. G.; Xu, J. C.; Zhao, X. Y.; Shi, Y.; Liu, C.; Pei, Z. K.

    2015-07-15

    A new scheme for proton acceleration by cascaded collisionless electrostatic shock (CES) is proposed. By irradiating a foil target with a moderate high-intensity laser beam, a stable CES field can be induced, which is employed as the accelerating field for the booster stage of proton acceleration. The mechanism is studied through simulations and theoretical analysis, showing that a 55 MeV seed proton beam can be further accelerated to 265 MeV while keeping a good energy spread. This scheme offers a feasible approach to produce proton beams with energy of hundreds of MeV by existing available high-intensity laser facilities.

  10. Interband Cascade Photovoltaic Cells

    SciTech Connect

    Yang, Rui Q.; Santos, Michael B.; Johnson, Matthew B.

    2014-09-24

    In this project, we are performing basic and applied research to systematically investigate our newly proposed interband cascade (IC) photovoltaic (PV) cells [1]. These cells follow from the great success of infrared IC lasers [2-3] that pioneered the use of quantum-engineered IC structures. This quantum-engineered approach will enable PV cells to efficiently convert infrared radiation from the sun or other heat source, to electricity. Such cells will have important applications for more efficient use of solar energy, waste-heat recovery, and power beaming in combination with mid-infrared lasers. The objectives of our investigations are to: achieve extensive understanding of the fundamental aspects of the proposed PV structures, develop the necessary knowledge for making such IC PV cells, and demonstrate prototype working PV cells. This research will focus on IC PV structures and their segments for utilizing infrared radiation with wavelengths from 2 to 5 μm, a range well suited for emission by heat sources (1,000-2,000 K) that are widely available from combustion systems. The long-term goal of this project is to push PV technology to longer wavelengths, allowing for relatively low-temperature thermal sources. Our investigations address material quality, electrical and optical properties, and their interplay for the different regions of an IC PV structure. The tasks involve: design, modeling and optimization of IC PV structures, molecular beam epitaxial growth of PV structures and relevant segments, material characterization, prototype device fabrication and testing. At the end of this program, we expect to generate new cutting-edge knowledge in the design and understanding of quantum-engineered semiconductor structures, and demonstrate the concepts for IC PV devices with high conversion efficiencies.

  11. Electromagnetic emissions from black hole spacetimes

    NASA Astrophysics Data System (ADS)

    Lehner, Luis; Garrett, Travis; Hirschmann, Eric; Liebling, Steven; Neilsen, David; Motl, Patrick; Palenzuela, Carlos

    2011-04-01

    Many of the expected astrophysical sources of gravitational waves may also be bright in the electromagnetic spectrum. Concurrent detection in both electromagnetic and gravitational bands promises significant gains in our ability to understand such systems. We discuss how black holes inmersed on the external magnetic field from a circumbinary disk produces a collimated e mission in the form of electromagnetic jets. In particular we illustrate the behavior of single and binary black holes and the depedence of jet with spin and black hole motion.

  12. Cascading processes in the nonlinear diffraction of light by standing acoustic waves

    NASA Astrophysics Data System (ADS)

    Dadoenkova, Yu. S.; Dadoenkova, N. N.; Bentivegna, F. F. L.; Lyubchanskii, I. L.; Lee, Y. P.

    2016-01-01

    The contribution of two types of cascading process to the nonlinear optical diffraction of electromagnetic waves from a standing acoustic wave in a GaAs crystal is theoretically studied. The first type of cascading process results from second-harmonic generation followed by linear acousto-optical diffraction, while the second type involves linear acousto-optical diffraction from the standing acoustic wave and subsequent sum-frequency generation. In contrast to the third, direct, nonlinear acousto-optical diffraction process we previously investigated, the photoelastic interaction between electromagnetic and acoustic waves is here linear. We establish the rules governing the cascading processes and show that in most cases the output signal simultaneously results from two or even three of the possible nonlinear diffraction mechanisms. However, we demonstrate that a careful choice of the incidence angles of the incoming electromagnetic waves, of the polarization combinations of the incoming and diffracted waves, and of the type of acoustic wave (longitudinal or transverse) makes it always possible to distinguish between the direct and either of the two cascading processes.

  13. Pair Cascades in Blazars and Radio Galaxies

    NASA Astrophysics Data System (ADS)

    Roustazadeh Sheikhyousefi, Parisa

    2012-05-01

    Recently some intermediate BL Lac objects (IBL), low frequency peak BL Lac objects (LBL) and flat spectrum radio quasars (FSRQs) were detected as very high energy gamma-ray sources (VHE; E > 100 GeV) by the Major Atmospheric Gamma-ray Imaging Cherenkov Telescope (MAGIC), the High Energy Stereoscopic System (H.E.S.S) and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). These discoveries suggest that VHE gamma-rays may be produced in all types of active galactic nuclei (AGN) and that this is not only a common property of high frequency peaked BL Lac objects (HBL). The detection of the radio galaxies M87, Cen A and NGC 1275 supports this idea. In those AGN, VHE photons may interact with low energy photons from the broadline region (BLR), accretion disk around the black hole or thermal infrared photons form a dust torus by photon-photon pair production if the total center-of-momentum frame energy is above threshold to produce an electron-positron pair. These particles can produce new high energy photons by Compton up-scattering, and again these high energy photons can interact with soft photons to produce a pair of particles. This process will continue, leading to a shower (cascade) of particles and radiation. As the shower develops, it will expand laterally. This may explain the detection of the radio galaxies as VHE gamma-ray sources. The central part of my Ph.D. research work deals with the theoretical simulation of very high energy gamma-ray induced pair cascades in blazars and radio galaxies. Gamma-rays from the core of the AGN interact with low energy photons from the AGN environment and produce pairs of electrons and positrons resulting in Compton supported pair cascades. I developed a Monte Carlo code which treats the processes of gamma-gamma absorption and pair production, gamma-ray and electron/positron propagation, and Compton scattering, tracking particle trajectories in full 3-dimensional geometry. I showed that even for a very weak

  14. Cascaded-cladding-pumped cascaded Raman fiber amplifier.

    PubMed

    Jiang, Huawei; Zhang, Lei; Feng, Yan

    2015-06-01

    The conversion efficiency of double-clad Raman fiber laser is limited by the cladding-to-core area ratio. To get high conversion efficiency, the inner-cladding-to-core area ratio has to be less than about 8, which limits the brightness enhancement. To overcome the problem, a cascaded-cladding-pumped cascaded Raman fiber laser with multiple-clad fiber as the Raman gain medium is proposed. A theoretical model of Raman fiber amplifier with multiple-clad fiber is developed, and numerical simulation proves that the proposed scheme can improve the conversion efficiency and brightness enhancement of cladding pumped Raman fiber laser. PMID:26072764

  15. Experiment Pamir-4: Analysis of superfamily with halo of electromagnetic nature detected in deep XEC

    NASA Technical Reports Server (NTRS)

    Zatsepin, G. T.

    1985-01-01

    The family Pb2-11 was detected in the multilayer lead XEC with total thickness of 100 c.u. exposed at the Pamirs. Each lead layer was 1 cm thick, the first registering layer being located under 2 cm of Pb(= 4 c.u.). The family comprised a narrow group of gamma-rays which near the maximum of cascade development (= 14 c.u.) produced a dark spot of optical density D approx. .4 over area S = 25 sq.mm. The narrow group of gamma-rays was traced up to 14th layer corresponding to 30 c.u. Deeper in the chamber, for the space of 70 c.u. no hadron cascade was observed. Thus, the pure electromagnetic halo could be assumed. Preliminary results of the analysis of the family Pb2-11 was presented. The methods of estimation of energy of primary particle and height of nuclear interaction responsible for the observed halo are considered in more detail.

  16. Rescuing Ecosystems from Extinction Cascades

    NASA Astrophysics Data System (ADS)

    Sahasrabudhe, Sagar; Motter, Adilson

    2010-03-01

    Food web perturbations stemming from climate change, overexploitation, invasive species, and natural disasters often cause an initial loss of species that results in a cascade of secondary extinctions. Using a predictive modeling framework, here we will present a systematic network-based approach to reduce the number of secondary extinctions. We will show that the extinction of one species can often be compensated by the concurrent removal of a second specific species, which is a counter-intuitive effect not previously tested in complex food webs. These compensatory perturbations frequently involve long-range interactions that are not a priori evident from local predator-prey relationships. Strikingly, in numerous cases even the early removal of a species that would eventually be extinct by the cascade is found to significantly reduce the number of cascading extinctions. Other nondestructive interventions based on partial removals and growth suppression and/or mortality increase are shown to sometimes prevent all secondary extinctions.

  17. Autoregressive cascades on random networks

    NASA Astrophysics Data System (ADS)

    Iyer, Srikanth K.; Vaze, Rahul; Narasimha, Dheeraj

    2016-04-01

    A network cascade model that captures many real-life correlated node failures in large networks via load redistribution is studied. The considered model is well suited for networks where physical quantities are transmitted, e.g., studying large scale outages in electrical power grids, gridlocks in road networks, and connectivity breakdown in communication networks, etc. For this model, a phase transition is established, i.e., existence of critical thresholds above or below which a small number of node failures lead to a global cascade of network failures or not. Theoretical bounds are obtained for the phase transition on the critical capacity parameter that determines the threshold above and below which cascade appears or disappears, respectively, that are shown to closely follow numerical simulation results.

  18. Electromagnetic structure of pion

    SciTech Connect

    Mello, Clayton S.; Cruz Filho, Jose P.; Da Silva, Edson O.; El-Bennich, Bruno; De Melo, J. P.; Filho, Victo S.

    2013-03-25

    In this work, we analyze the electromagnetic structure of the pion, an elementary particle composed by a quark-antiquark bound state, by considering the calculation of its electromagnetic radius and its electromagnetic form factor in low and intermediate energy range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion, in the formalism of the light-front field theory. In particular, it is considered a nonsymmetrical vertex for such a model, in which we have calculated the electromagnetic form factor of the pion in an optimized way, by varying its regulator mass, so that we can obtain the best value for the pion electromagnetic radius when compared with the experimental one. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

  19. General introduction to microstructural evolution under cascade damage conditions

    SciTech Connect

    Wiedersich, H.

    1993-06-01

    A short overview of the processes that affect the evolution of the microstructure during irradiation is given. The processes include defect production with an emphasis on the effects of the dynamic cascade events, defect clustering, irradiation-enhanced diffusion, radiation-induced segregation, phase decompositions and phase transformations. A simple model for the description of the development of the defect microstructure in a pure metal during cascade producing irradiation is also outlined which can provide, in principle, defect fluxes required for the description of the microstructural processes such as phase decomposition and irradiation-induced precipitation.

  20. Superradiant cascade in a seeded free-electron laser.

    PubMed

    Giannessi, L; Bellaveglia, M; Chiadroni, E; Cianchi, A; Couprie, M E; Del Franco, M; Di Pirro, G; Ferrario, M; Gatti, G; Labat, M; Marcus, G; Mostacci, A; Petralia, A; Petrillo, V; Quattromini, M; Rau, J V; Spampinati, S; Surrenti, V

    2013-01-25

    We report measurements demonstrating the concept of the free-electron laser (FEL) superradiant cascade. Radiation (λ(rad) = 200 nm) at the second harmonic of a short, intense seed laser pulse (λ(seed) = 400 nm) was generated by the cascaded FEL scheme at the transition between the modulator and radiator undulator sections. The superradiance of the ultrashort pulse is confirmed by detailed measurements of the resulting spectral structure, the intensity level of the produced harmonics, and the trend of the energy growth along the undulator. These results are compared to numerical particle simulations using the FEL code GENESIS 1.3 and show a satisfactory agreement. PMID:25166168

  1. Substrate channelling as an approach to cascade reactions

    NASA Astrophysics Data System (ADS)

    Wheeldon, Ian; Minteer, Shelley D.; Banta, Scott; Barton, Scott Calabrese; Atanassov, Plamen; Sigman, Matthew

    2016-04-01

    Millions of years of evolution have produced biological systems capable of efficient one-pot multi-step catalysis. The underlying mechanisms that facilitate these reaction processes are increasingly providing inspiration in synthetic chemistry. Substrate channelling, where intermediates between enzymatic steps are not in equilibrium with the bulk solution, enables increased efficiencies and yields in reaction and diffusion processes. Here, we review different mechanisms of substrate channelling found in nature and provide an overview of the analytical methods used to quantify these effects. The incorporation of substrate channelling into synthetic cascades is a rapidly developing concept, and recent examples of the fabrication of cascades with controlled diffusion and flux of intermediates are presented.

  2. Nanowire terahertz quantum cascade lasers

    SciTech Connect

    Grange, Thomas

    2014-10-06

    Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.

  3. The Collisional Cascade Model For Saturn's Ring Spokes

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.; Jontof-Hutter, D.

    2014-12-01

    Dust particles are ubiquitous in the saturnian system, spewing forth from the geysers of Enceladus and lurking as mysterious wedge-shaped spokes in the planet's main rings. The smallest dust grains are strongly influenced by electromagnetic forces arising from the motions of charged dust particles relative to Saturn's rotating magnetic field while large dust grains follow Keplerian paths determined by the planet's gravity. The most interesting dynamics result when the two forces have similar strengths, typically for particles ~100 nanometer in size. Differences between the motions of dust grains and much larger ring particles provides a free energy source that powers spoke formation. Most observations of ongoing spoke formation can be understood in the context of a Collisional Cascade model in which a hail of rapidly-moving ~50nm dust grains rain down upon more massive ring particles. After leaving the ring plane en masse from the site of an initial disturbance, these mid-sized grains are accelerated by the magnetic field to high speeds relative to ring particles. When they return to the ring plane - nearly simultaneously over a large radial range - they strike dust-coated fluffy ring particles, freeing both visible 0.5 micron spoke particles and additional 50nm debris that goes on to continue the cascade. The Collisional Cascade model can account for the rapid onset of spokes, their hour-long active phases, and the propensity of spokes to prefer certain magnetic longitudes.

  4. THz quantum cascade lasers for standoff molecule detection.

    SciTech Connect

    Chow, Weng Wah; Wanke, Michael Clement; Lerttamrab, Maytee; Waldmueller, Ines

    2007-10-01

    Remote optical detection of molecules, agents, and energetic materials has many applications to national security interests. Currently there is significant interest in determining under what circumstances THz frequency coverage will aid in a complete sensing package. Sources of coherent THz frequency (i.e. 0.1 to 10 THz) electromagnetic radiation with requisite power levels, frequency agility, compactness and reliability represent the single greatest obstacle in establishing a THz technology base, but recent advances in semiconductor-based quantum cascade lasers (QCLs) offer huge improvements towards the ultimate THz source goals. This project advanced the development of narrow-linewidth THz quantum cascade lasers. We developed theoretical tools to guide the improvement of standard THz quantum cascade lasers, the investigation of nonlinear optics employing infrared QCLs, and the exploration of quantum coherence to improve QCL performance. The latter was aimed especially towards achieving high temperature operation. In addition we developed a computer algorithm capable of shifting the frequencies of an existing THz QCL to a different frequency and invented a new type of laser that may enable room temperature THz generation in a electrically driven solid-state source.

  5. Pair Cascades and Deathlines in Offset Magnetic Dipole Fields

    NASA Technical Reports Server (NTRS)

    Harding, Alice; Muslimov, Alex

    2010-01-01

    We investigate electron-positron pair cascades in a dipole magnetic field whose axis is offset from the neutron star center. In such a field geometry, the polar cap is displaced from the neutron star symmetry axis and the field line radius of curvature is modified. Using the modified parallel electric field near the polar cap of an offset dipole, we simulate pair cascades to determine the pair deathlines and pair multiplicities as a function of the offset parameter. We find that the pair multiplicity can change dramatically with a modest offset, with a significant increase on one side of the polar cap. Lower pair deathlines allow a larger fraction of the pulsar population, that include old and millisecond pulsars, to produce cascades with high multiplicity.

  6. Cascaded Linear Shift-Invariant Processors in Optical Pattern Recognition

    NASA Astrophysics Data System (ADS)

    Reed, Stuart; Coupland, Jeremy

    2001-08-01

    We study a cascade of linear shift-invariant processing modules (correlators), each augmented with a nonlinear threshold as a means to increase the performance of high-speed optical pattern recognition. This configuration is a special class of multilayer, feed-forward neural networks and has been proposed in the literature as a relatively fast best-guess classifier. However, it seems that, although cascaded correlation has been proposed in a number of specific pattern recognition problems, the importance of the configuration has been largely overlooked. We prove that the cascaded architecture is the exact structure that must be adopted if a multilayer feed-forward neural network is trained to produce a shift-invariant output. In contrast with more generalized multilayer networks, the approach is easily implemented in practice with optical techniques and is therefore ideally suited to the high-speed analysis of large images. We have trained a digital model of the system using a modified backpropagation algorithm with optimization using simulated annealing techniques. The resulting cascade has been applied to a defect recognition problem in the canning industry as a benchmark for comparison against a standard linear correlation filter, the minimum average correlation energy (MACE) filter. We show that the nonlinear performance of the cascade is a significant improvement over that of the linear MACE filter in this case.

  7. Cascaded linear shift-invariant processors in optical pattern recognition.

    PubMed

    Reed, S; Coupland, J

    2001-08-10

    We study a cascade of linear shift-invariant processing modules (correlators), each augmented with a nonlinear threshold as a means to increase the performance of high-speed optical pattern recognition. This configuration is a special class of multilayer, feed-forward neural networks and has been proposed in the literature as a relatively fast best-guess classifier. However, it seems that, although cascaded correlation has been proposed in a number of specific pattern recognition problems, the importance of the configuration has been largely overlooked. We prove that the cascaded architecture is the exact structure that must be adopted if a multilayer feed-forward neural network is trained to produce a shift-invariant output. In contrast with more generalized multilayer networks, the approach is easily implemented in practice with optical techniques and is therefore ideally suited to the high-speed analysis of large images. We have trained a digital model of the system using a modified backpropagation algorithm with optimization using simulated annealing techniques. The resulting cascade has been applied to a defect recognition problem in the canning industry as a benchmark for comparison against a standard linear correlation filter, the minimum average correlation energy (MACE) filter. We show that the nonlinear performance of the cascade is a significant improvement over that of the linear MACE filter in this case. PMID:18360417

  8. A new adaptive hybrid electromagnetic damper: modelling, optimization, and experiment

    NASA Astrophysics Data System (ADS)

    Asadi, Ehsan; Ribeiro, Roberto; Behrad Khamesee, Mir; Khajepour, Amir

    2015-07-01

    This paper presents the development of a new electromagnetic hybrid damper which provides regenerative adaptive damping force for various applications. Recently, the introduction of electromagnetic technologies to the damping systems has provided researchers with new opportunities for the realization of adaptive semi-active damping systems with the added benefit of energy recovery. In this research, a hybrid electromagnetic damper is proposed. The hybrid damper is configured to operate with viscous and electromagnetic subsystems. The viscous medium provides a bias and fail-safe damping force while the electromagnetic component adds adaptability and the capacity for regeneration to the hybrid design. The electromagnetic component is modeled and analyzed using analytical (lumped equivalent magnetic circuit) and electromagnetic finite element method (FEM) (COMSOL® software package) approaches. By implementing both modeling approaches, an optimization for the geometric aspects of the electromagnetic subsystem is obtained. Based on the proposed electromagnetic hybrid damping concept and the preliminary optimization solution, a prototype is designed and fabricated. A good agreement is observed between the experimental and FEM results for the magnetic field distribution and electromagnetic damping forces. These results validate the accuracy of the modeling approach and the preliminary optimization solution. An analytical model is also presented for viscous damping force, and is compared with experimental results The results show that the damper is able to produce damping coefficients of 1300 and 0-238 N s m-1 through the viscous and electromagnetic components, respectively.

  9. Characteristics for two kinds of cascading events

    NASA Astrophysics Data System (ADS)

    Zou, Sheng-Rong; Gu, Ai-Hua; Liu, Ai-Fen; Xu, Xiu-Lian; Wang, Jian; He, Da-Ren

    2011-04-01

    Avalanche or cascade failure is ubiquitous. We first classify the cascading phenomena into two categories: the cascading disasters which result in large-scale functional failures and the cascading events that do not lead to disasters. We elucidate that two important factors, the increasing amount of events and the acceleration of event frequency, can induce the crossover from the cascading phenomenon to the cascading disaster. Through a simplified sandpile model and a heuristic logistic map, we demonstrate that the dependence of the event number on the observation time behaves as a power-law and as an exponential for these two different cascading events, respectively. The analytic derivations are found to be consistent with several empirical observations. Our present findings contribute to the understanding of the transition between different cascading events, providing a basis for the further understanding of the transitions among more general critical events.

  10. Engineering Light: Quantum Cascade Lasers

    ScienceCinema

    Claire Gmachl

    2010-09-01

    Quantum cascade lasers are ideal for environmental sensing and medical diagnostic applications. Gmachl discusses how these lasers work, and their applications, including their use as chemical trace gas sensors. As examples of these applications, she briefly presents results from her field campaign at the Beijing Olympics, and ongoing campaigns in Texas, Maryland, and Ghana.

  11. Applications of cascade multilevel inverters.

    PubMed

    Peng, Fang-zen; Qian, Zhao-ming

    2003-01-01

    Cascade multilevel inverters have been developed for electric utility applications. A cascade M-level inverter consists of (M-1)/2 H-bridges in which each bridge's dc voltage is supported by its own dc capacitor. The new inverter can: (1) generate almost sinusoidal waveform voltage while only switching one time per fundamental cycle; (2) dispense with multi-pulse inverters' transformers used in conventional utility interfaces and static var compensators; (3) enables direct parallel or series transformer-less connection to medium- and high-voltage power systems. In short, the cascade inverter is much more efficient and suitable for utility applications than traditional multi-pulse and pulse width modulation (PWM) inverters. The authors have experimentally demonstrated the superiority of the new inverter for power supply, (hybrid) electric vehicle (EV) motor drive, reactive power (var) and harmonic compensation. This paper summarizes the features, feasibility, and control schemes of the cascade inverter for utility applications including utility interface of renewable energy, voltage regulation, var compensation, and harmonic filtering in power systems. Analytical, simulated, and experimental results demonstrated the superiority of the new inverters. PMID:14566981

  12. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  13. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  14. Electromagnetic mass revisited

    NASA Astrophysics Data System (ADS)

    Schwinger, Julian

    1983-03-01

    Examples of uniformly moving charge distributions that possess conserved electromagnetic stress tensors are exhibited. These constitute stable systems with covariantly characterized electromagnetic mass. This note, on a topic to which Paul Dirac made a significant contribution in 1938, is dedicated to him for his 80th birthday.

  15. Electromagnetically Operated Counter

    DOEpatents

    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.

  16. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  17. Critical transitions in colliding cascades

    PubMed

    Gabrielov; Keilis-Borok; Zaliapin; Newman

    2000-07-01

    We consider here the interaction of direct and inverse cascades in a hierarchical nonlinear system that is continuously loaded by external forces. The load is applied to the largest element and is transferred down the hierarchy to consecutively smaller elements, thereby forming a direct cascade. The elements of the system fail (i. e., break down) under the load. The smallest elements fail first. The failures gradually expand up the hierarchy to the larger elements, thus forming an inverse cascade. Eventually the failures heal, ensuring that the system will function indefinitely. The direct and inverse cascades collide and interact. Loading triggers the failures, while failures release and redistribute the load. Notwithstanding its relative simplicity, this model reproduces the major dynamical features observed in seismicity, including the seismic cycle, intermittence of seismic regime, power-law energy distribution, clustering in space and time, long-range correlations, and a set of seismicity patterns premonitory to a strong earthquake. In this context, the hierarchical structure of the model crudely imitates a system of tectonic blocks spread by a network of faults (note that the behavior of such a network is different from that of a single fault). Loading mimics the impact of tectonic forces, and failures simulate earthquakes. The model exhibits three basic types of premonitory pattern reflecting seismic activity, clustering of earthquakes in space and time, and the range of correlation between the earthquakes. The colliding-cascade model seemingly exhibits regularities that are common in a wide class of complex hierarchical systems, not necessarily Earth specific. PMID:11088457

  18. PANEL CODE FOR PLANAR CASCADES

    NASA Technical Reports Server (NTRS)

    Mcfarland, E. R.

    1994-01-01

    The Panel Code for Planar Cascades was developed as an aid for the designer of turbomachinery blade rows. The effective design of turbomachinery blade rows relies on the use of computer codes to model the flow on blade-to-blade surfaces. Most of the currently used codes model the flow as inviscid, irrotational, and compressible with solutions being obtained by finite difference or finite element numerical techniques. While these codes can yield very accurate solutions, they usually require an experienced user to manipulate input data and control parameters. Also, they often limit a designer in the types of blade geometries, cascade configurations, and flow conditions that can be considered. The Panel Code for Planar Cascades accelerates the design process and gives the designer more freedom in developing blade shapes by offering a simple blade-to-blade flow code. Panel, or integral equation, solution techniques have been used for several years by external aerodynamicists who have developed and refined them into a primary design tool of the aircraft industry. The Panel Code for Planar Cascades adapts these same techniques to provide a versatile, stable, and efficient calculation scheme for internal flow. The code calculates the compressible, inviscid, irrotational flow through a planar cascade of arbitrary blade shapes. Since the panel solution technique is for incompressible flow, a compressibility correction is introduced to account for compressible flow effects. The analysis is limited to flow conditions in the subsonic and shock-free transonic range. Input to the code consists of inlet flow conditions, blade geometry data, and simple control parameters. Output includes flow parameters at selected control points. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 590K of 8 bit bytes. This program was developed in 1982.

  19. Frequency division using a micromechanical resonance cascade

    SciTech Connect

    Qalandar, K. R. Gibson, B.; Sharma, M.; Ma, A.; Turner, K. L.; Strachan, B. S.; Shaw, S. W.

    2014-12-15

    A coupled micromechanical resonator array demonstrates a mechanical realization of multi-stage frequency division. The mechanical structure consists of a set of N sequentially perpendicular microbeams that are connected by relatively weak elastic elements such that the system vibration modes are localized to individual microbeams and have natural frequencies with ratios close to 1:2:⋯:2{sup N}. Conservative (passive) nonlinear inter-modal coupling provides the required energy transfer between modes and is achieved by finite deformation kinematics. When the highest frequency beam is excited, this arrangement promotes a cascade of subharmonic resonances that achieve frequency division of 2{sup j} at microbeam j for j = 1, …, N. Results are shown for a capacitively driven three-stage divider in which an input signal of 824 kHz is passively divided through three modal stages, producing signals at 412 kHz, 206 kHz, and 103 kHz. The system modes are characterized and used to delineate the range of AC input voltages and frequencies over which the cascade occurs. This narrow band frequency divider has simple design rules that are scalable to higher frequencies and can be extended to a larger number of modal stages.

  20. Electron Acceleration by Cascading Reconnection in the Solar Corona. II. Resistive Electric Field Effects

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Büchner, J.; Bárta, M.; Gan, W.; Liu, S.

    2016-08-01

    We investigate electron acceleration by electric fields induced by cascading reconnections in current sheets trailing coronal mass ejections via a test particle approach in the framework of the guiding-center approximation. Although the resistive electric field is much weaker than the inductive electric field, the electron acceleration is still dominated by the former. Anomalous resistivity η is switched on only in regions where the current carrier’s drift velocity is large enough. As a consequence, electron acceleration is very sensitive to the spatial distribution of the resistive electric fields, and electrons accelerated in different segments of the current sheet have different characteristics. Due to the geometry of the 2.5-dimensional electromagnetic fields and strong resistive electric field accelerations, accelerated high-energy electrons can be trapped in the corona, precipitating into the chromosphere or escaping into interplanetary space. The trapped and precipitating electrons can reach a few MeV within 1 s and have a very hard energy distribution. Spatial structure of the acceleration sites may also introduce breaks in the electron energy distribution. Most of the interplanetary electrons reach hundreds of keV with a softer distribution. To compare with observations of solar flares and electrons in solar energetic particle events, we derive hard X-ray spectra produced by the trapped and precipitating electrons, fluxes of the precipitating and interplanetary electrons, and electron spatial distributions.

  1. Operation of a Wideband Terahertz Superconducting Bolometer Responding to Quantum Cascade Laser Pulses

    NASA Astrophysics Data System (ADS)

    Cibella, S.; Beck, M.; Carelli, P.; Castellano, M. G.; Chiarello, F.; Faist, J.; Leoni, R.; Ortolani, M.; Sabbatini, L.; Scalari, G.; Torrioli, G.; Turcinkova, D.

    2012-06-01

    We make use of a niobium film to produce a micrometric vacuum-bridge superconducting bolometer responding to THz frequency. The bolometer works anywhere in the temperature range 2-7 K, which can be easily reached in helium bath cryostats or closed-cycle cryocoolers. In this work the bolometer is mounted on a pulse tube refrigerator and operated to measure the equivalent noise power (NEP) and the response to fast (μs) terahertz pulses. The NEP above 100 Hz equals that measured in a liquid helium cryostat showing that potential drawbacks related to the use of a pulse tube refrigerator (like mechanical and thermal oscillations, electromagnetic interference, noise) are irrelevant. At low frequency, instead, the pulse tube expansion-compression cycles originate lines at 1 Hz and harmonics in the noise spectrum. The bolometer was illuminated with THz single pulses coming either from a Quantum Cascade Laser operating at liquid nitrogen temperature or from a frequency-multiplied electronic oscillator. The response of the bolometer to the single pulses show that the device can track signals with a rise time as fast as about 450 ns.

  2. Electromagnetic induction studies. [of earth lithosphere and asthenosphere

    NASA Technical Reports Server (NTRS)

    Hermance, J. F.

    1983-01-01

    Recent developments in electromagnetic induction studies of the lithosphere and the asthenosphere are reviewed. Attention is given to geoelectrical studies of active tectonic areas in terms of the major zones of crustal extension, the basin and range province along western regions of North America, and the Rio Grande rift. Studies have also been performed of tectonic activity around Iceland, the Salton Trough and Cerro Prieto, and the subduction zones of the Cascade Mountains volcanic belt, where magnetotelluric and geomagnetic variation studies have been done. Geomagnetic variations experiments have been reported in the Central Appalachians, and submarine electromagnetic studies along the Juan de Fuca ridge. Controlled source electromagnetic and dc resistivity investigations have been carried out in Nevada, Hawaii, and in the Adirondacks Mountains. Laboratory examinations on the conductivity of representative materials over a broad range of temperature, pressure, and chemistry are described.

  3. Electromagnetically driven peristaltic pump

    DOEpatents

    Marshall, Douglas W.

    2000-01-01

    An electromagnetic peristaltic pump apparatus may comprise a main body section having an inlet end and an outlet end and a flexible membrane which divides the main body section into a first cavity and a second cavity. The first cavity is in fluid communication with the inlet and outlet ends of the main body section. The second cavity is not in fluid communication with the first cavity and contains an electrically conductive fluid. The second cavity includes a plurality of electrodes which are positioned within the second cavity generally adjacent the flexible membrane. A magnetic field generator produces a magnetic field having a plurality of flux lines at least some of which are contained within the second cavity of the main body section and which are oriented generally parallel to a flow direction in which a material flows between the inlet and outlet ends of the main body section. A control system selectively places a voltage potential across selected ones of the plurality of electrodes to deflect the flexible membrane in a wave-like manner to move material contained in the first cavity between the inlet and outlet ends of the main body section.

  4. SOLAR NANTENNA ELECTROMAGNETIC COLLECTORS

    SciTech Connect

    Steven D. Novack; Dale K. Kotter; Dennis Slafer; Patrick Pinhero

    2008-08-01

    This research explores a new efficient approach for producing electricity from the abundant energy of the sun. A nanoantenna electromagnetic collector (NEC) has been designed, prototyped, and tested. Proof of concept has been validated. The device targets mid-infrared wavelengths where conventional photovoltaic (PV) solar cells do not respond but is abundant in solar energy. The initial concept of designing NEC antennas was based on scaling of radio frequency antenna theory. This approach has proven unsuccessful by many due to not fully understanding and accounting for the optical behavior of materials in the THz region. Also until recent years the nanofabrication methods were not available to fabricate the optical antenna elements. We have addressed and overcome both technology barriers. Several factors were critical in successful implementation of NEC including: 1) frequency-dependent modeling of antenna elements, 2) selection of materials with proper THz properties and 3) novel manufacturing methods that enable economical large-scale manufacturing. The work represents an important step toward the ultimate realization of a low-cost device that will collect as well as convert this radiation into electricity, which will lead to a wide spectrum, high conversion efficiency, and low cost solution to complement conventional PVs.

  5. Electromagnetically induced transparency (EIT)-like transmission in side-coupled complementary split-ring resonators.

    PubMed

    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. PMID:23187197

  6. Shielding effect of mineral schungite during electromagnetic irradiation of rats.

    PubMed

    Kurotchenko, S P; Subbotina, T I; Tuktamyshev, I I; Tuktamyshev, I Sh; Khadartsev, A A; Yashin, A A

    2003-11-01

    We studied the effect of nonthermal 37-GHz radiation on hemopoiesis in schungite-shielded Wistar rats. Radiation with right-handed or left-handed rotation of the polarization plane of electromagnetic wave was used. Shielding with schungite decreased the severity of damage produced by high-frequency electromagnetic radiation. PMID:14968159

  7. Energy spectrum of cascade showers induced by cosmic ray muons in the range from 50 GeV to 5 TeV

    NASA Technical Reports Server (NTRS)

    Ashitkov, V. D.; Kirina, T. M.; Klimakov, A. P.; Kokoulin, R. P.; Petrukhin, A. A.; Yumatov, V. I.

    1985-01-01

    The energy spectrum of cascade showers induced by electromagnetic interactions of high energy muons of horizontal cosmic ray flux in iron absorber was measured. The total observation time exceeded 22,000 hours. Both the energy spectrum and angular distributions of cascade showers are fairly described in terms of the usual muon generation processes, with a single power index of the parent meson spectrum over the muon energy range from 150 GeV to 5 TeV.

  8. Electromagnetic Heating Methods for Heavy Oil Reservoirs

    SciTech Connect

    Sahni, A.; Kumar, M.; Knapp, R.B.

    2000-05-01

    The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations.

  9. Electromagnetic Induction with Neodymium Magnets

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Sebranek, John

    2013-09-01

    In April 1820, Hans Christian Ørsted noticed that the needle of a nearby compass deflected briefly from magnetic north each time the electric current of the battery he was using for an unrelated experiment was turned on or off. Upon further investigation, he showed that an electric current flowing through a wire produces a magnetic field. In 1831 Michael Faraday and Joseph Henry separately expanded on Ørsted's discovery by showing that a changing magnetic field produces an electric current. Heinrich Lenz found in 1833 that an induced current has the opposite direction from the electromagnetic force that produced it. This paper describes an experiment that can help students to develop an understanding of Faraday's law and Lenz's law by studying the emf generated as a magnet drops through a set of coils having increasing numbers of turns.

  10. Atomistic Simulation of Collision Cascades in Zircon

    SciTech Connect

    Devanathan, Ram; Corrales, Louis R.; Weber, William J.; Chartier, Alain; Meis, Constantin

    2006-09-01

    Defect production in energetic collision cascades in zircon has been studied by molecular dynamics simulation using a partial charge model combined with the Ziegler-Biersack-Littmark potential. Energy dissipation, defect accumulation, Si-O-Si polymerization, and Zr coordination number were examined for 10 keV and 30 keV U recoils simulated in the constant NVE ensemble. For both energies an amorphous core was produced with features similar to that of melt quenched zircon. Disordered Si ions in this core were polymerized with an average degree of polymerization of 1.5, while disordered Zr ions showed a coordination number of about 6 in agreement with EXAFS results. These results suggest that nano-scale phase separation into silica- and zirconia-rich regions occurs in the amorphous core.

  11. High frequency electromagnetic tomography

    SciTech Connect

    Daily, W.; Ramirez, A.; Ueng, T.; Latorre, R.

    1989-09-01

    An experiment was conducted in G Tunnel at the Nevada Test Site to evaluate high frequency electromagnetic tomography as a candidate for in situ monitoring of hydrology in the near field of a heater placed in densely welded tuff. Tomographs of 200 MHz electromagnetic permittivity were made for several planes between boreholes. Data were taken before the heater was turned on, during heating and during cooldown of the rockmass. This data is interpreted to yield maps of changes in water content of the rockmass as a function of time. This interpretation is based on laboratory measurement of electromagnetic permittivity as a function of water content for densely welded tuff. 8 refs., 6 figs.

  12. Electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Garcia-Sucerquia, Jorge

    2006-01-01

    The recently introduced concept of spatial coherence wavelets is generalized to describe 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 for the analysis of 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 further insight about the causal relationship between the polarization states at different planes along the propagation path. PMID:16478063

  13. Bankruptcy Cascades in Interbank Markets

    PubMed Central

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank’s liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  14. Cascade Chaotic System With Applications.

    PubMed

    Zhou, Yicong; Hua, Zhongyun; Pun, Chi-Man; Chen, C L Philip

    2015-09-01

    Chaotic maps are widely used in different applications. Motivated by the cascade structure in electronic circuits, this paper introduces a general chaotic framework called the cascade chaotic system (CCS). Using two 1-D chaotic maps as seed maps, CCS is able to generate a huge number of new chaotic maps. Examples and evaluations show the CCS's robustness. Compared with corresponding seed maps, newly generated chaotic maps are more unpredictable and have better chaotic performance, more parameters, and complex chaotic properties. To investigate applications of CCS, we introduce a pseudo-random number generator (PRNG) and a data encryption system using a chaotic map generated by CCS. Simulation and analysis demonstrate that the proposed PRNG has high quality of randomness and that the data encryption system is able to protect different types of data with a high-security level. PMID:25373135

  15. Bankruptcy cascades in interbank markets.

    PubMed

    Tedeschi, Gabriele; Mazloumian, Amin; Gallegati, Mauro; Helbing, Dirk

    2012-01-01

    We study a credit network and, in particular, an interbank system with an agent-based model. To understand the relationship between business cycles and cascades of bankruptcies, we model a three-sector economy with goods, credit and interbank market. In the interbank market, the participating banks share the risk of bad debits, which may potentially spread a bank's liquidity problems through the network of banks. Our agent-based model sheds light on the correlation between bankruptcy cascades and the endogenous economic cycle of booms and recessions. It also demonstrates the serious trade-off between, on the one hand, reducing risks of individual banks by sharing them and, on the other hand, creating systemic risks through credit-related interlinkages of banks. As a result of our study, the dynamics underlying the meltdown of financial markets in 2008 becomes much better understandable. PMID:23300760

  16. Lens Coupled Quantum Cascade Laser

    NASA Technical Reports Server (NTRS)

    Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor)

    2013-01-01

    Terahertz quantum cascade (QC) devices are disclosed that can operate, e.g., in a range of about 1 THz to about 10 THz. In some embodiments, QC lasers are disclosed in which an optical element (e.g., a lens) is coupled to an output facet of the laser's active region to enhance coupling of the lasing radiation from the active region to an external environment. In other embodiments, terahertz amplifier and tunable terahertz QC lasers are disclosed.

  17. Electromagnetism in the Movies.

    ERIC Educational Resources Information Center

    Everitt, Lori R.; Patterson, Evelyn T.

    1999-01-01

    Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

  18. An opening electromagnetic transducer

    NASA Astrophysics Data System (ADS)

    Sun, Yanhua; Kang, Yihua

    2013-12-01

    Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

  19. Pair cascades in the magnetospheres of strongly magnetized neutron stars

    NASA Astrophysics Data System (ADS)

    Medin, Zach; Lai, Dong

    2010-08-01

    We present numerical simulations of electron-positron pair cascades in the magnetospheres of magnetic neutron stars for a wide range of surface fields (Bp = 1012-1015 G), rotation periods (0.1-10 s) and field geometries. This has been motivated by the discovery in recent years of a number of radio pulsars with inferred magnetic fields comparable to those of magnetars. Evolving the cascade generated by a primary electron or positron after it has been accelerated in the inner gap of the magnetosphere, we follow the spatial development of the cascade until the secondary photons and electron-positron pairs leave the magnetosphere, and we obtain the pair multiplicity and the energy spectra of the cascade pairs and photons under various conditions. Going beyond previous works, which were restricted to weaker fields (B <~ afew × 1012 G), we have incorporated in our simulations detailed treatments of physical processes that are potentially important (especially in the high-field regime) but were either neglected or crudely treated before, including photon splitting with the correct selection rules for photon polarization modes, one-photon pair production into low Landau levels for the e+/-, and resonant inverse Compton scattering from polar cap hotspots. We find that even for B >> BQ = 4 × 1013 G, photon splitting has a small effect on the multiplicity of the cascade since a majority of the photons in the cascade cannot split. One-photon decay into e+ e- pairs at low Landau levels, however, becomes the dominant pair production channel when B >~ 3 × 1012 G; this tends to suppress synchrotron radiation so that the cascade can develop only at a larger distance from the stellar surface. Nevertheless, we find that the total number of pairs and their energy spectrum produced in the cascade depend mainly on the polar cap voltage BpP-2, and are weakly dependent on Bp (and P) alone. We discuss the implications of our results for the radio pulsar death line and for the hard X

  20. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  1. Descriptive Study of Electromagnetic Wave Distribution for Various Seating Positions: Using Digital Textbooks

    ERIC Educational Resources Information Center

    Seomun, GyeongAe; Kim, YoungHwan; Lee, Jung-Ah; Jeong, KwangHoon; Park, Seon-A; Kim, Miran; Noh, Wonjung

    2014-01-01

    To better understand environmental electromagnetic wave exposure during the use of digital textbooks by elementary school students, we measured numeric values of the electromagnetic fields produced by tablet personal computers (TPCs). Specifically, we examined the distribution of the electromagnetic waves for various students' seating…

  2. Compton Sources of Electromagnetic Radiation

    SciTech Connect

    Geoffrey Krafft,Gerd Priebe

    2011-01-01

    When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

  3. SURFACE AND BOREHOLE ELECTROMAGNETIC IMAGING OF CONDUCTING CONTAMINANT PLUMES

    EPA Science Inventory

    Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component ma...

  4. Cascade of parametric resonances in coupled Josephson junctions

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Azemtsa-Donfack, H.; Rahmonov, I. R.; Botha, A. E.

    2016-06-01

    We found that the coupled system of Josephson junctions under external electromagnetic radiation demonstrates a cascade of parametric instabilities. These instabilities appear along the IV characteristics within bias current intervals corresponding to Shapiro step subharmonics and lead to charging in the superconducting layers. The amplitudes of the charge oscillations increase with increasing external radiation power. We demonstrate the existence of longitudinal plasma waves at the corresponding bias current values. An essential advantage of the parametric instabilities in the case of subharmonics is the lower amplitude of radiation that is needed for the creation of the longitudinal plasma wave. This fact gives a unique possibility to create and control longitudinal plasma waves in layered superconductors. We propose a novel experiment for studying parametric instabilities and the charging of superconducting layers based on the simultaneous variation of the bias current and radiation amplitude.

  5. Molecular dynamics studies of displacement cascades in Fe-Y2TiO5 system

    NASA Astrophysics Data System (ADS)

    Dholakia, Manan; Chandra, Sharat; Jaya, S. Mathi

    2016-05-01

    The effect of displacement cascade on Fe-Y2TiO5 bilayer is studied using classical molecular dynamics simulations. Different PKA species - Fe, Y, Ti and O - with the same PKA energy of 8 keV are used to produce displacement cascades that encompass the interface. It is shown that Ti atom has the highest movement in the ballistic regime of cascades which can lead to Ti atoms moving out of the oxide clusters into the Fe matrix in ODS alloys.

  6. A novel fast optical switch based on two cascaded Terahertz Optical Asymmetric Demultiplexers (TOAD)

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Baby, Varghese; Tong, Wilson; Xu, Lei; Friedman, Michelle; Runser, Robert J.; Glesk, Ivan; Prucnal, Paul R.

    2002-01-01

    A novel optical switch based on cascading two terahertz optical asymmetric demultiplexers (TOAD) is presented. By utilizing the sharp edge of the asymmetric TOAD switching window profile, two TOAD switching windows are overlapped to produce a narrower aggregate switching window, not limited by the pulse propagation time in the SOA of the TOAD. Simulations of the cascaded TOAD switching window show relatively constant window amplitude for different window sizes. Experimental results on cascading two TOADs, each with a switching window of 8ps, but with the SOA on opposite sides of the fiber loop, show a minimum switching window of 2.7ps.

  7. Effects of in-cascade defect clustering on near-term defect evolution

    SciTech Connect

    Heinisch, H.L.

    1997-08-01

    The effects of in-cascade defect clustering on the nature of the subsequent defect population are being studied using stochastic annealing simulations applied to cascades generated in molecular dynamics (MD) simulations. The results of the simulations illustrates the strong influence of the defect configuration existing in the primary damage state on subsequent defect evolution. The large differences in mobility and stability of vacancy and interstitial defects and the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades have been shown to be significant factors affecting the evolution of the defect distribution. In recent work, the effects of initial cluster sizes appear to be extremely important.

  8. Cascade upgrading of γ-valerolactone to biofuels.

    PubMed

    Yan, Kai; Lafleur, Todd; Wu, Xu; Chai, Jiajue; Wu, Guosheng; Xie, Xianmei

    2015-04-25

    Cascade upgrading of γ-valerolactone (GVL), produced from renewable cellulosic biomass, with selective conversion to biofuels pentyl valerate (PV) and pentane in one pot using a bifunctional Pd/HY catalyst is described. Excellent catalytic performance (over 99% conversion of GVL, 60.6% yield of PV and 22.9% yield of pentane) was achieved in one step. These biofuels can be targeted for gasoline and jet fuel applications. PMID:25797827

  9. Cascade frequency generation regime in an optical parametric oscillator

    SciTech Connect

    Kolker, D B; Dmitriev, Aleksandr K; Gorelik, P; Vong, Franko; Zondy, J J

    2009-05-31

    In a parametric oscillator of a special two-sectional design based on a lithium niobate periodic structure, a cascade frequency generation regime was observed in which a signal wave pumped a secondary parametric oscillator, producing secondary signal and idler waves. The secondary parametric oscillator can be tuned in a broad range of {approx}200 nm with respect to a fixed wavelength of the primary idler wave. (nonlinear optical phenomena)

  10. Electromagnetic or other directed energy pulse launcher

    SciTech Connect

    Ziolkowski, R.W.

    1990-09-25

    The physical realization of new solutions of wave propagation equations, such as Maxwell's equations and the scaler wave equation, produces localized pulses of wave energy such as electromagnetic or acoustic energy which propagate over long distances without divergence. This patent describes how the pulses are produced by driving each element of an array of radiating sources with a particular drive function so that the resultant localized packet of energy closely approximates the exact solutions and behaves the same.

  11. Electromagnetic or other directed energy pulse launcher

    DOEpatents

    Ziolkowski, Richard W.

    1990-01-01

    The physical realization of new solutions of wave propagation equations, such as Maxwell's equations and the scaler wave equation, produces localized pulses of wave energy such as electromagnetic or acoustic energy which propagate over long distances without divergence. The pulses are produced by driving each element of an array of radiating sources with a particular drive function so that the resultant localized packet of energy closely approximates the exact solutions and behaves the same.

  12. Eruptive history of South Sister, Oregon Cascades

    USGS Publications Warehouse

    Fierstein, J.; Hildreth, W.; Calvert, A.T.

    2011-01-01

    South Sister is southernmost and highest of the Three Sisters, three geologically dissimilar stratovolcanoes that together form a spectacular 20km reach along the Cascade crest in Oregon. North Sister is a monotonously mafic edifice as old as middle Pleistocene, Middle Sister a basalt-andesite-dacite cone built between 48 and 14ka, and South Sister is a basalt-free edifice that alternated rhyolitic and intermediate modes from 50ka to 2ka (largely contemporaneous with Middle Sister). Detailed mapping, 330 chemical analyses, and 42 radioisotopic ages show that the oldest exposed South Sister lavas were initially rhyolitic ~50ka. By ~37ka, rhyolitic lava flows and domes (72-74% SiO2) began alternating with radially emplaced dacite (63-68% SiO2) and andesite (59-63% SiO2) lava flows. Construction of a broad cone of silicic andesite-dacite (61-64% SiO2) culminated ~30ka in a dominantly explosive sequence that began with crater-forming andesitic eruptions that left fragmental deposits at least 200m thick. This was followed at ~27ka by growth of a steeply dipping summit cone of agglutinate-dominated andesite (56-60.5% SiO2) and formation of a summit crater ~800m wide. This crater was soon filled and overtopped by a thick dacite lava flow and then by >150m of dacitic pyroclastic ejecta. Small-volume dacite lavas (63-67% SiO2) locally cap the pyroclastic pile. A final sheet of mafic agglutinate (54-56% SiO2) - the most mafic product of South Sister - erupted from and drapes the small (300-m-wide) present-day summit crater, ending a summit-building sequence that lasted until ~22ka. A 20kyr-long-hiatus was broken by rhyolite eruptions that produced (1) the Rock Mesa coulee, tephra, and satellite domelets (73.5% SiO2) and (2) the Devils Chain of ~20 domes and short coulees (72.3-72.8% SiO2) from N-S vent alignments on South Sister's flanks. The compositional reversal from mafic summit agglutinate to recent rhyolites epitomizes the frequently changing compositional modes of the

  13. Cascade defense via routing in complex networks

    NASA Astrophysics Data System (ADS)

    Xu, Xiao-Lan; Du, Wen-Bo; Hong, Chen

    2015-05-01

    As the cascading failures in networked traffic systems are becoming more and more serious, research on cascade defense in complex networks has become a hotspot in recent years. In this paper, we propose a traffic-based cascading failure model, in which each packet in the network has its own source and destination. When cascade is triggered, packets will be redistributed according to a given routing strategy. Here, a global hybrid (GH) routing strategy, which uses the dynamic information of the queue length and the static information of nodes' degree, is proposed to defense the network cascade. Comparing GH strategy with the shortest path (SP) routing, efficient routing (ER) and global dynamic (GD) routing strategies, we found that GH strategy is more effective than other routing strategies in improving the network robustness against cascading failures. Our work provides insight into the robustness of networked traffic systems.

  14. Quantum cascade lasers with dual-wavelength interdigitated cascades

    NASA Astrophysics Data System (ADS)

    Mosely, Trinesha S.; Straub, Axel; Gmachl, Claire; Colombelli, Raffaele; Troccoli, Mariano; Capasso, Federico; Sivco, Deborah L.; Cho, Alfred Y.

    2002-03-01

    A quantum cascade (QC) laser with a dual-wavelength interdigitated cascade is presented. Its active core consists of a stack of active regions and injectors designed for emission at one wavelength (8.0 μm) interleaved with a second stack emitting at a substantially different wavelength (9.5 μm), and the two injectors were designed to either bridge the 8.0 μm active region to the 9.5 μm one, or vice versa. Clear two-wavelength laser action is observed, demonstrating the viability of this approach to achieve multi-wavelength laser emission in the mid-infrared. Aside from providing two-wavelength operation, this laser design can also be used to test the role of charge transport in the injectors, which customarily bridge successive active regions together. We will present early results of this study. The work was partly supported by DARPA/US ARO under contract number DAAD19-00-C-0096. A. S. acknowledges the support of the Deutsche Studienstiftung. T. S. M. present address: Southern University and A&M College, Baton Rouge, LA.

  15. Very high energy gamma rays from active galactic nuclei: Cascading on the cosmic background radiation fields and the formation of pair halos

    NASA Technical Reports Server (NTRS)

    Aharonian, F. A.; Coppi, P. S.; Voelk, H. J.

    1994-01-01

    Recent high-energy gamma-ray observations (E(sub gamma) greater than 100 MeV) of blazar Active Galactic Nuclei (AGNs) show emission spectra with no clear upper energy cutoff. AGNs, considered to be possible sources for the observed flux of cosmic rays beyond 10(exp 19) eV, may well have emission extending into the very high energy (VHE), (E(sub gamma) greater than 100 GeV) domain. Because VHE gamma-rays are absorbed by pair production on the intergalactic background radiation fields, much of this emission may not be directly visible. The electromagnetic cascades initiated by absorbed VHE gamma-rays, however, may be observable. Since, most probably, the velocities of (e(+), e(-)) pairs produced in a cascade are quickly isotropized by an ambient random magnetic field, extended 'halos' (R greater than 1 Mpc) of pairs will be formed around AGNs with VHE emission. The cascade radiation from these pair halos is emitted isotropically and should be observable at energies below a few TeV. The halo radiation can be distinguished by its characteristic variation in spectrum and intensity with angular distance from the central source. This variation depends weakly on the details of the central source model, e.g., the orientation and beaming/opening angle of an emitting jet. Limiting or determining the intensity of the pair halo can thus serve as a model-independent bound on or measure of the VHE power of AGNs. Next-generation Cherenkov telescopes may be able to image a pair halo.

  16. Orexin/hypocretin receptor signalling cascades

    PubMed Central

    Kukkonen, JP; Leonard, CS

    2014-01-01

    Orexin (hypocretin) peptides and their two known G-protein-coupled receptors play essential roles in sleep–wake control and powerfully influence other systems regulating appetite/metabolism, stress and reward. Consequently, drugs that influence signalling by these receptors may provide novel therapeutic opportunities for treating sleep disorders, obesity and addiction. It is therefore critical to understand how these receptors operate, the nature of the signalling cascades they engage and their physiological targets. In this review, we evaluate what is currently known about orexin receptor signalling cascades, while a sister review (Leonard & Kukkonen, this issue) focuses on tissue-specific responses. The evidence suggests that orexin receptor signalling is multifaceted and is substantially more diverse than originally thought. Indeed, orexin receptors are able to couple to members of at least three G-protein families and possibly other proteins, through which they regulate non-selective cation channels, phospholipases, adenylyl cyclase, and protein and lipid kinases. In the central nervous system, orexin receptors produce neuroexcitation by postsynaptic depolarization via activation of non-selective cation channels, inhibition of K+ channels and activation of Na+/Ca2+ exchange, but they also can stimulate the release of neurotransmitters by presynaptic actions and modulate synaptic plasticity. Ca2+ signalling is also prominently influenced by these receptors, both via the classical phospholipase C−Ca2+ release pathway and via Ca2+ influx, mediated by several pathways. Upon longer-lasting stimulation, plastic effects are observed in some cell types, while others, especially cancer cells, are stimulated to die. Thus, orexin receptor signals appear highly tunable, depending on the milieu in which they are operating. Linked ArticlesThis article is part of a themed section on Orexin Receptors. To view the other articles in this section visit http://dx.doi.org/10

  17. How sesquiterpenes modulate signaling cascades in cancers.

    PubMed

    Jabeen, S; Qureshi, M Z; Attar, R; Aslam, A; Kanwal, S; Khalid, S; Qureshi, J M; Aras Perk, A; Farooqi, A A; Ismail, M

    2016-01-01

    Data obtained from high-throughput technologies has started to shed light on the interplay between signal transduction cascades and chromatin modifications thus adding another layer of complexity to the already complex regulation of the protein network. Based on the insights gleaned from almost a decade of research, it has now been convincingly revealed that sesquiterpenes effectively modulated different intracellular signaling cascades in different cancers. In this review we summarize how sesquiterpenes mediated Wnt, Shh, Notch and TRAIL induced signaling cascades. PMID:27453282

  18. Cascade photo production at CLAS

    SciTech Connect

    Goetz, John; Hicks, Kenneth H.

    2014-09-01

    The famous discovery of the Omega in 1964 put the quark model on firm ground and since then a lot of effort has been spent on mapping out the baryonic and mesonic states. Over the following decades, many excited baryons with light quarks (up, down and strange) have been measured, but by most predictions, only a small percentage of those expected have been found. In this talk, I will discuss a newly developing technique using an (unflavored) photon beam to excite protons to doubly-strange "Cascade" (Xi) states. Advantages of such an experiment and associated difficulties will be presented, along with recent results from the CLAS detector at Jefferson Lab in Virginia.

  19. Logic synthesis of cascade circuits

    NASA Astrophysics Data System (ADS)

    Zakrevskii, A. D.

    The work reviews aspects of the logic design of cascade circuits, particularly programmable logic matrices. Effective methods for solving various problems of the analysis and synthesis of these devices are examined; these methods are based on a matrix representation of the structure of these devices, and a vector-matrix interpretation of certain aspects of Boolean algebra. Particular consideration is given to the theory of elementary matrix circuits, methods for the minimization of Boolean functions, the synthesis of programmable logic matrices, multilevel combinational networks, and the development of automata with memory.

  20. Method of independently operating a group of stages within a diffusion cascade

    DOEpatents

    Benedict, Manson; Fruit, Allen J.; Levey, Horace B.

    1976-06-08

    1. A method of operating a group of the diffusion stages of a productive diffusion cascade with countercurrent flow, said group comprising a top and a bottom stage, which comprises isolating said group from said cascade, circulating the diffused gas produced in said top stage to the feed of said bottom stage while at the same time circulating the undiffused gas from said bottom stage to the feed of said top stage whereby major changes in

  1. Electromagnetically driven dwarf tornados in turbulent convection

    NASA Astrophysics Data System (ADS)

    Kenjereš, Saša

    2011-01-01

    Motivated by the concept of interdependency of turbulent flow and electromagnetic fields inside the spiraling galaxies, we explored the possibilities of generating a localized Lorentz force that will produce a three-dimensional swirling flow in weakly conductive fluids. Multiple vortical flow patterns were generated by combining arrays of permanent magnets and electrodes with supplied dc current. This concept was numerically simulated and applied to affect natural convection flow, turbulence, and heat transfer inside a rectangular enclosure heated from below and cooled from above over a range of Rayleigh numbers (104<=Ra<=5×109). The large-eddy simulations revealed that for low- and intermediate-values of Ra, the heat transfer was increased more than five times when an electromagnetic forcing was activated. In contrast to the generally accepted view that electromagnetic forcing will suppress velocity fluctuations and will increase anisotropy of turbulence, we demonstrated that localized forcing can enhance turbulence isotropy of thermal convection compared to its neutral state.

  2. Electromagnetic currents induced by color fields

    NASA Astrophysics Data System (ADS)

    Tanji, Naoto

    2015-12-01

    The quark production in classical color fields is investigated with a focus on the induction of an electromagnetic current by produced quarks. We show that the color SU(2) and the SU(3) theories lead significantly different results for the electromagnetic current. In uniform SU(2) color fields, the net electromagnetic current is not generated, while in SU(3) color fields the net current is induced depending on the color direction of background fields. Also the numerical study of the quark production in inhomogeneous color fields is done. Motivated by gauge field configurations provided by the color glass condensate framework, we introduce an ensemble of randomly distributed color electric fluxtubes. The spectrum of photons emitted from the quarks by a classical process is shown.

  3. Apparatus for processing electromagnetic radiation and method

    NASA Technical Reports Server (NTRS)

    Gatewood, George D. (Inventor)

    1983-01-01

    Measuring apparatus including a ruled member having alternate transparent and opaque zones. An optical coupler connecting the ruled member with electromagnetic radiation-conversion apparatus. The conversion apparatus may include a photomultiplier and a discriminator. Radiation impinging on the ruled member will, in part, be converted to electrical pulses which correspond to the intensity of the radiation. A method of processing electromagnetic radiation includes providing a member having alternating dark and light zones, establishing movement of the member through the beam of electromagnetic radiation with the dark zones interrupting passage of radiation through the rule, providing an optical coupler to connect a portion of the radiation with a conversion station where the radiation portion is converted into an electrical pulse which is related to the intensity of the radiation received at the conversion station. The electrical pulses may be counted and the digitized signals stored or permanently recorded to produce positional information.

  4. WHISTLER TURBULENCE FORWARD CASCADE VERSUS INVERSE CASCADE: THREE-DIMENSIONAL PARTICLE-IN-CELL SIMULATIONS

    SciTech Connect

    Chang, Ouliang; Gary, S. Peter; Wang, Joseph E-mail: pgary@lanl.gov

    2015-02-20

    We present the results of the first fully three-dimensional particle-in-cell simulations of decaying whistler turbulence in a magnetized, homogeneous, collisionless plasma in which both forward cascades to shorter wavelengths, and inverse cascades to longer wavelengths are allowed to proceed. For the electron beta β {sub e} = 0.10 initial value considered here, the early-time rate of inverse cascade is very much smaller than the rate of forward cascade, so that at late times the fluctuation energy in the regime of the inverse cascade is much weaker than that in the forward cascade regime. Similarly, the wavevector anisotropy in the inverse cascade regime is much weaker than that in the forward cascade regime.

  5. Lie cascades and Random Dynamical Systems

    NASA Astrophysics Data System (ADS)

    Schertzer, D.; Lovejoy, S.; Tchiguirinskaia, I.

    2009-04-01

    Lie cascades were defined as a broad generalization of scalar cascades (Schertzer and Lovejoy 1995, Tchiguirinskaia and Schertzer, 1996) with the help of (infinitesimal) sub-generators being white noise vector fields on manifolds, instead of being white noise scalar fields on vector spaces. Lie cascades were thus closely related to stochastic flows on manifolds as defined by Kunita (1990). However, the concept of random dynamical systems (Arnold,1998) allows to make a closer and simpler connection between stochastic differential equations and the dynamical system approach. In this talk, we point out some relationships between Lie cascades and random dynamical systems, and therefore to dynamical system approach.

  6. Contingency Analysis of Cascading Line Outage Events

    SciTech Connect

    Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

    2011-03-01

    As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

  7. Cascade control and defense in complex networks.

    PubMed

    Motter, Adilson E

    2004-08-27

    Complex networks with a heterogeneous distribution of loads may undergo a global cascade of overload failures when highly loaded nodes or edges are removed due to attacks or failures. Since a small attack or failure has the potential to trigger a global cascade, a fundamental question regards the possible strategies of defense to prevent the cascade from propagating through the entire network. Here we introduce and investigate a costless strategy of defense based on a selective further removal of nodes and edges, right after the initial attack or failure. This intentional removal of network elements is shown to drastically reduce the size of the cascade. PMID:15447153

  8. Dynamics and structure of energetic displacement cascades

    SciTech Connect

    Averback, R.S.; Diaz de la Rubia, T.; Benedek, R.

    1987-12-01

    This paper summarizes recent progress in the understanding of energetic displacement cascades and the primary state of damage in metals. On the theoretical side, the availability of supercomputers has greatly enhanced our ability to simulate cascades by molecular dynamics. Recent application of this simulation technique to Cu and Ni provides new insight into the dynamics of cascade processes. On the experimental side, new data on ion beam mixing and in situ electron microscopy studies of ion damage at low temperatures reveal the role of the thermodynamic properties of the material on cascade dynamics and structure. 38 refs., 9 figs.

  9. Tri-bimaximal Mixing from Cascades

    SciTech Connect

    Takahashi, Ryo

    2008-11-23

    We investigate fermion mass matrices of the cascade form which lead to the tri-bimaximal mixing in the lepton sector. The cascade neutrino matrix predicts a parameter-independent relation among the observables, which are the neutrino mixing angles and mass squared differences. The relation predicts that the atmospheric neutrino mixing angle is close to maximal. We also study phenomenological aspect of the cascade form in supersymmetric theory, which are lepton flavor violation and thermal leptogenesis. A dynamical realivation of the cascade mass matrix are also presented in U(1) flavor theory.

  10. Simulation Modeling of an Enhanced Low-Emission Swirl-Cascade Burner

    SciTech Connect

    Ala Qubbaj

    2004-09-01

    ''Cascade-burners'' is a passive technique to control the stoichiometry of the flame through changing the flow dynamics and rates of mixing in the combustion zone with a set of venturis surrounding the flame. Cascade-burners have shown advantages over other techniques; its reliability, flexibility, safety, and cost makes it more attractive and desirable. On the other hand, the application of ''Swirl-burners'' has shown superiority in producing a stable flame under a variety of operating conditions and fuel types. The basic idea is to impart swirl to the air or fuel stream, or both. This not only helps to stabilize the flame but also enhances mixing in the combustion zone. As a result, nonpremixed (diffusion) swirl burners have been increasingly used in industrial combustion systems such as gas turbines, boilers, and furnaces, due to their advantages of safety and stability. Despite the advantages of cascade and swirl burners, both are passive control techniques, which resulted in a moderate pollutant emissions reduction compared to SCR, SNCR and FGR (active) methods. The present investigation will study the prospects of combining both techniques in what to be named as ''an enhanced swirl-cascade burner''. Natural gas jet diffusion flames in baseline, cascade, swirl, and swirl-cascade burners were numerically modeled using CFDRC package. The thermal, composition, and flow (velocity) fields were simulated. The numerical results showed that swirl and cascade burners have a more efficient fuel/air mixing, a shorter flame, and a lower NOx emission levels, compared to the baseline case. The results also revealed that the optimal configurations of the cascaded and swirling flames have not produced an improved performance when combined together in a ''swirl-cascade burner''. The non-linearity and complexity of the system accounts for such a result, and therefore, all possible combinations, i.e. swirl numbers (SN) versus venturi diameter ratios (D/d), need to be considered.

  11. Electromagnetic attachment mechanism

    NASA Technical Reports Server (NTRS)

    Monford, Leo G., Jr. (Inventor)

    1992-01-01

    An electromagnetic attachment mechanism is disclosed for use as an end effector of a remote manipulator system. A pair of electromagnets, each with a U-shaped magnetic core with a pull-in coil and two holding coils, are mounted by a spring suspension system on a base plate of the mechanism housing with end pole pieces adapted to move through openings in the base plate when the attractive force of the electromagnets is exerted on a strike plate of a grapple fixture affixed to a target object. The pole pieces are spaced by an air gap from the strike plate when the mechanism first contacts the grapple fixture. An individual control circuit and power source is provided for the pull-in coil and one holding coil of each electromagnet. A back-up control circuit connected to the two power sources and a third power source is provided for the remaining holding coils. When energized, the pull-in coils overcome the suspension system and air gap and are automatically de-energized when the pole pieces move to grapple and impose a preload force across the grapple interface. A battery backup is a redundant power source for each electromagnet in each individual control circuit and is automatically connected upon failure of the primary source. A centerline mounted camera and video monitor are used in cooperation with a target pattern on the reflective surface of the strike plate to effect targeting and alignment.

  12. Astrophysical Gyrokinetics: Kinetic and Fluid Turbulent Cascades In Magentized Weakly Collisional Plasmas

    SciTech Connect

    Schekochihin, A. A.; Cowley, S. C.; Dorland, W.; Hammett, G. W.; Howes, G. G.; Quataert, E.; Tatsuno, T.

    2009-04-23

    This paper presents a theoretical framework for understanding plasma turbulence in astrophysical plasmas. It is motivated by observations of electromagnetic and density fluctuations in the solar wind, interstellar medium and galaxy clusters, as well as by models of particle heating in accretion disks. All of these plasmas and many others have turbulentmotions at weakly collisional and collisionless scales. The paper focuses on turbulence in a strong mean magnetic field. The key assumptions are that the turbulent fluctuations are small compared to the mean field, spatially anisotropic with respect to it and that their frequency is low compared to the ion cyclotron frequency. The turbulence is assumed to be forced at some system-specific outer scale. The energy injected at this scale has to be dissipated into heat, which ultimately cannot be accomplished without collisions. A kinetic cascade develops that brings the energy to collisional scales both in space and velocity. The nature of the kinetic cascade in various scale ranges depends on the physics of plasma fluctuations that exist there. There are four special scales that separate physically distinct regimes: the electron and ion gyroscales, the mean free path and the electron diffusion scale. In each of the scale ranges separated by these scales, the fully kinetic problem is systematically reduced to a more physically transparent and computationally tractable system of equations, which are derived in a rigorous way. In the "inertial range" above the ion gyroscale, the kinetic cascade separates into two parts: a cascade of Alfvenic fluctuations and a passive cascade of density and magnetic-fieldstrength fluctuations. The former are governed by the Reduced Magnetohydrodynamic (RMHD) equations at both the collisional and collisionless scales; the latter obey a linear kinetic equation along the (moving) field lines associated with the Alfvenic component (in the collisional limit, these compressive fluctuations

  13. Physics of interband cascade lasers

    NASA Astrophysics Data System (ADS)

    Vurgaftman, I.; Bewley, W. W.; Merritt, C. D.; Canedy, C. L.; Kim, C. S.; Abell, J.; Meyer, J. R.; Kim, M.

    2012-01-01

    The interband cascade laser (ICL) is a unique device concept that combines the effective parallel connection of its multiple-quantum-well active regions, interband active transitions, and internal generation of electrons and holes at a semimetallic interface within each stage of the device. The internal generation of carriers becomes effective under bias, and the role of electrical injection is to replenish the carriers consumed by recombination processes. Major strides have been made toward fundamentally understanding the rich and intricate ICL physics, which has in turn led to dramatic improvements in the device performance. In this article, we review the physical principles of the ICL operation and designs of the active region, electron and hole injectors, and optical waveguide. The results for state-of- the-art ICLs spanning the 3-6 μm wavelength range are also briefly reviewed. The cw threshold input powers at room temperature are more than an order of magnitude lower than those for quantum cascade lasers throughout the mid-IR spectral range. This will lengthen battery lifetimes and greatly relax packaging and size/weight requirements for fielded sensing systems.

  14. Electromagnetically induced gain in molecular systems

    NASA Astrophysics Data System (ADS)

    Mukherjee, Nandini; Patel, C. Kumar N.

    2009-12-01

    We report electromagnetically induced gain in a highly degenerate two-level rotational vibrational molecular system. Using two photon (Raman-type) interaction with right and left circularly polarized pump and probe waves, the Zeeman coherence is established within the manifold of degenerate sublevels belonging to a rotational vibrational eigenstate. We analytically and numerically calculate the third-order nonlinear optical susceptibility for a Doppler-broadened molecular transition for an arbitrary high rotational angular momentum (J≥20) . It is shown that for a Q -type open transition, a weak probe will experience an electromagnetically induced gain in presence of a strong copropagating pump wave. The inversionless gain originates due to cancellation of absorption from the interference of the coupled Λ - and V-type excitation channels in an N -type configuration. A detailed analysis of the optical susceptibility as a function of Doppler detuning explains how the gain bands are generated in a narrow transparency window from the overlapping contributions of different velocity groups. It is shown that the orientation dependent coherent interaction in presence of a strong pump induces narrow resonances for the probe susceptibility. The locations, intensity, and sign (positive or negative susceptibility) of these resonances are decided by the frequency detuning of the Doppler group and the strength of the coupling field. The availability of high power tunable quantum cascade lasers covering a spectral region from about 4 to 12μm opens up the possibility of investigating the molecular vibrational rotational transitions for a variety of coherent effects.

  15. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  16. Electromagnetic energy sink

    NASA Astrophysics Data System (ADS)

    Valagiannopoulos, C. A.; Vehmas, J.; Simovski, C. R.; Tretyakov, S. A.; Maslovski, S. I.

    2015-12-01

    The ideal black body fully absorbs all incident rays, that is, all propagating waves created by arbitrary sources. A known idealized realization of the black body is the perfectly matched layer (PML), widely used in numerical electromagnetics. However, ideal black bodies and PMLs do not interact with evanescent fields that exists near any finite-size source, and the energy stored in these fields cannot be harvested. Here, we introduce the concept of the ideal conjugate matched layer (CML), which fully absorbs the energy of both propagating and evanescent fields of sources acting as an ideal sink for electromagnetic energy. Conjugate matched absorbers have exciting application potentials, as resonant attractors of electromagnetic energy into the absorber volume. We derive the conditions on the constitutive parameters of media which can serve as CML materials, numerically study the performance of planar and cylindrical CML and discuss possible realizations of such materials as metal-dielectric composites.

  17. Aircraft electromagnetic compatibility

    NASA Astrophysics Data System (ADS)

    Clarke, Clifton A.; Larsen, William E.

    1987-06-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  18. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  19. Electromagnetic properties of baryons

    SciTech Connect

    Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M.; Martin-Camalich, J.

    2011-10-21

    We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

  20. EMACK electromagnetic launcher commissioning

    NASA Astrophysics Data System (ADS)

    Deis, D. W.; Scherbarth, D. W.; Ferrentino, G. L.

    1984-03-01

    The Laboratory Demonstration Electromagnetic Launcher Program (EMACK) was initiated in April 1979, with the objective to design, construct, and demonstrate a complete electromagnetic launcher (EML) system capable of accelerating projectiles of substantial mass to velocities significantly greater than those achievable with conventional chemical systems. The last hardware was installed in late 1981. During February 1982, a series of five test shots was made to evaluate the system's performance. Particular attention is given to the parameters of the final, as-built hardware, and the results of the commissioning tests. The results of these tests have demonstrated the viability of the components required for large scale electromagnetic launchers. It has been shown that large projectiles with velocities significantly greater than those achievable by chemical systems can be accelerated intact.

  1. Metamaterial electromagnetic wave absorbers.

    PubMed

    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. PMID:22627995

  2. Superconducting dipole electromagnet

    DOEpatents

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  3. Improved Electromagnetic Brake

    NASA Technical Reports Server (NTRS)

    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

  4. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  5. Introducing electromagnetic field momentum

    NASA Astrophysics Data System (ADS)

    Yu-Kuang Hu, Ben

    2012-07-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional analysis and without using vector calculus identities or the need to evaluate integrals. I use this result to show that linear and angular momenta are conserved for a charge in the presence of a magnetic dipole when the dipole strength is changed.

  6. Electromagnetic propulsion test facility

    NASA Technical Reports Server (NTRS)

    Gooder, S. T.

    1984-01-01

    A test facility for the exploration of electromagnetic propulsion concept is described. The facility is designed to accommodate electromagnetic rail accelerators of various lengths (1 to 10 meters) and to provide accelerating energies of up to 240 kiloJoules. This accelerating energy is supplied as a current pulse of hundreds of kiloAmps lasting as long as 1 millisecond. The design, installation, and operating characteristics of the pulsed energy system are discussed. The test chamber and its operation at pressures down to 1300 Pascals (10 mm of mercury) are described. Some aspects of safety (interlocking, personnel protection, and operating procedures) are included.

  7. Effect of tubing deposition, breathing pattern, and temperature on aerosol mass distribution measured by cascade impactor.

    PubMed

    Gurses, Burak K; Smaldone, Gerald C

    2003-01-01

    Aerosols produced by nebulizers are often characterized on the bench using cascade impactors. We studied the effects of connecting tubing, breathing pattern, and temperature on mass-weighted aerodynamic particle size aerosol distributions (APSD) measured by cascade impaction. Our experimental setup consisted of a piston ventilator, low-flow (1.0 L/min) cascade impactor, two commercially available nebulizers that produced large and small particles, and two "T"-shaped tubes called "Tconnector(cascade)" and "Tconnector(nebulizer)" placed above the impactor and the nebulizer, respectively. Radiolabeled normal saline was nebulized using an airtank at 50 PSIG; APSD, mass balance, and Tconnector(cascade) deposition were measured with a gamma camera and radioisotope calibrator. Flow through the circuit was defined by the air tank (standing cloud, 10 L/min) with or without a piston pump, which superimposed a sinusoidal flow on the flow from the air tank (tidal volume and frequency of breathing). Experiments were performed at room temperature and in a cooled environment. With increasing tidal volume and frequency, smaller particles entered the cascade impactor (decreasing MMAD; e.g., Misty-Neb, 4.2 +/- 0.9 microm at lowest ventilation and 2.7 +/- 0.1 microm at highest, p = 0.042). These effects were reduced in magnitude for the nebulizer that produced smaller particles (AeroTech II, MMAD 1.8 +/- 0.1 to 1.3 +/- 0.1 microm; p = 0.0044). Deposition on Tconnector(cascade) increased with ventilation but was independent of cascade impactor flow. Imaging of the Tconnector(cascade) revealed a pattern of deposition unaffected by cascade impactor flow. These measurements suggest that changes in MMAD with ventilation were not artifacts of tubing deposition in the Tconnector(cascade). At lower temperatures, APSD distributions were more polydisperse. Our data suggest that, during patient inhalation, changes in particle distribution occur that are related to conditions in the tubing and

  8. Seismic electromagnetic study in China

    NASA Astrophysics Data System (ADS)

    Huang, Qinghua

    2016-04-01

    Seismo-electromagnetism is becoming a hot interdisciplinary study in both geosciences and electromagnetism. Numerous electromagnetic changes at a broad range of frequencies associated with earthquakes have been reported independently. There are some attempts of applying such electromagnetic data to short-term earthquake prediction. Although due to the complexity of seismogenic process and underground structure, the seismic electromagnetic phenomena cannot be fully understood, the seismic electromagnetic study plays a key role in the mitigation of seismic hazard. China is one of the countries which have the earliest reports on seismo-electromagnetic phenomena. The seismic electromagnetic study in China started in late 1960's. There are almost 50 years continuous observation data up to now, which provides a unique database for seismo-electromagnetic study not only in China, but also in the world. Therefore, seismo-electromagnetic study in China is interested broadly by international communities of geosciences and electromagnetism. I present here a brief review on seismic electromagnetic study in China, especially focusing on geo-electromagnetic observation and empirical prediction based on the observation data. After summarizing various electromagnetic observations such as apparent resistivity, geoelectric potential, geomagnetic field, electromagnetic disturbance, and so on, I show the cases of the empirical prediction based on the observed electromagnetic data associated with some earthquakes in China. Finally, based on the above review, I propose an integrated research scheme of earthquake-related electromagnetic phenomena, which includes the interaction between appropriate observations, robust methodology of data processing, and theoretical model analysis. This study is supported partially by the National Natural Science Foundation of China (41274075) and the National Basic Research Program of China (2014CB845903).

  9. Methodology of Blade Unsteady Pressure Measurement in the NASA Transonic Flutter Cascade

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; McFarland, E. R.; Capece, V. R.; Jett, T. A.; Senyitko, R. G.

    2002-01-01

    In this report the methodology adopted to measure unsteady pressures on blade surfaces in the NASA Transonic Flutter Cascade under conditions of simulated blade flutter is described. The previous work done in this cascade reported that the oscillating cascade produced waves, which for some interblade phase angles reflected off the wind tunnel walls back into the cascade, interfered with the cascade unsteady aerodynamics, and contaminated the acquired data. To alleviate the problems with data contamination due to the back wall interference, a method of influence coefficients was selected for the future unsteady work in this cascade. In this approach only one blade in the cascade is oscillated at a time. The majority of the report is concerned with the experimental technique used and the experimental data generated in the facility. The report presents a list of all test conditions for the small amplitude of blade oscillations, and shows examples of some of the results achieved. The report does not discuss data analysis procedures like ensemble averaging, frequency analysis, and unsteady blade loading diagrams reconstructed using the influence coefficient method. Finally, the report presents the lessons learned from this phase of the experimental effort, and suggests the improvements and directions of the experimental work for tests to be carried out for large oscillation amplitudes.

  10. Effect of Axial Velocity Density Ratio on the Performance of a Controlled Diffusion Airfoil Compressor Cascade

    NASA Astrophysics Data System (ADS)

    Senthil Kumaran, R.; Kamble, Sachin; Swamy, K. M. M.; Nagpurwala, Q. H.; Bhat, Ananthesha

    2015-12-01

    Axial Velocity Density Ratio (AVDR) is an important parameter to check the two-dimensionality of cascade flows. It can have significant influence on the cascade performance and the secondary flow structure. In the present study, the effect of AVDR has been investigated on a highly loaded Controlled Diffusion airfoil compressor cascade. Detailed 3D Computational Fluid Dynamics (CFD) studies were carried out with the cascade at five different AVDRs. Key aerodynamic performance parameters and flow structure through the cascade were analyzed in detail. CFD results of one AVDR were validated with the experimental cascade test data and were seen to be in good agreement. Loss characteristics of the cascade varied significantly with change in AVDR. Increase in AVDR postponed the point of separation on the suction surface, produced thinner boundary layers and caused substantial drop in the pressure loss coefficient. Strong end wall vortices were noticed at AVDR of 1.177. At higher AVDRs, the flow was well guided even close to the end wall and the secondary flows diminished. The loading initially improved with increase in AVDR. Beyond a certain limit, further increase in AVDR offered no improvements to the loading but rather resulted in drop in diffusion and deviation.