Magnetic Field Topology in Jets

NASA Technical Reports Server (NTRS)

Gardiner, T. A.; Frank, A.

2000-01-01

We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.

Sensitivity of jet substructure to jet-induced medium response

NASA Astrophysics Data System (ADS)

Milhano, Guilherme; Wiedemann, Urs Achim; Zapp, Korinna Christine

2018-04-01

Jet quenching in heavy ion collisions is expected to be accompanied by recoil effects, but unambiguous signals for the induced medium response have been difficult to identify so far. Here, we argue that modern jet substructure measurements can improve this situation qualitatively since they are sensitive to the momentum distribution inside the jet. We show that the groomed subjet shared momentum fraction zg, and the girth of leading and subleading subjets signal recoil effects with dependencies that are absent in a recoilless baseline. We find that recoil effects can explain most of the medium modifications to the zg distribution observed in data. Furthermore, for jets passing the Soft Drop Condition, recoil effects induce in the differential distribution of subjet separation ΔR12 a characteristic increase with ΔR12, and they introduce a characteristic enhancement of the girth of the subleading subjet with decreasing zg. We explain why these qualitatively novel features, that we establish in JEWEL+PYTHIA simulations, reflect generic physical properties of recoil effects that should therefore be searched for as telltale signatures of jet-induced medium response.

Yang-Mills gauge conditions from Witten's open string field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng Haidong; Siegel, Warren

2007-02-15

We construct the Zinn-Justin-Batalin-Vilkovisky action for tachyons and gauge bosons from Witten's 3-string vertex of the bosonic open string without gauge fixing. Through canonical transformations, we find the off-shell, local, gauge-covariant action up to 3-point terms, satisfying the usual field theory gauge transformations. Perturbatively, it can be extended to higher-point terms. It also gives a new gauge condition in field theory which corresponds to the Feynman-Siegel gauge on the world-sheet.

Investigation on cone jetting regimes of liquid droplets subjected to pyroelectric fields induced by laser blasts

NASA Astrophysics Data System (ADS)

Gennari, Oriella; Battista, Luigi; Silva, Benjamin; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Coppola, Sara; Orlando, Pierangelo; Aprin, Laurent; Slangen, Pierre; Ferraro, Pietro

2015-02-01

Electrical conductivity and viscosity play a major role in the tip jetting behaviour of liquids subjected to electrohydrodynamic (EHD) forces, thus influencing significantly the printing performance. Recently, we developed a nozzle- and electrode-free pyro-EHD system as a versatile alternative to conventional EHD configurations and we demonstrated different applications, including inkjet printing and three-dimensional lithography. However, only dielectric fluids have been used in all of those applications. Here, we present an experimental characterization of the pyro-EHD jetting regimes, induced by laser blasts, of sessile drops in case of dielectric and conductive liquids in order to extend the applicability of the system to a wider variety of fields including biochemistry and biotechnology where conductive aqueous solutions are typically used.

Highly effective action from large N gauge fields

NASA Astrophysics Data System (ADS)

Yang, Hyun Seok

2014-10-01

Recently Schwarz put forward a conjecture that the world-volume action of a probe D3-brane in an AdS5×S5 background of type IIB superstring theory can be reinterpreted as the highly effective action (HEA) of four-dimensional N =4 superconformal field theory on the Coulomb branch. We argue that the HEA can be derived from the noncommutative (NC) field theory representation of the AdS/CFT correspondence and the Seiberg-Witten (SW) map defining a spacetime field redefinition between ordinary and NC gauge fields. It is based only on the well-known facts that the master fields of large N matrices are higher-dimensional NC U(1) gauge fields and the SW map is a local coordinate transformation eliminating U(1) gauge fields known as the Darboux theorem in symplectic geometry.

Canonical field anticommutators in the extended gauged Rarita-Schwinger theory

NASA Astrophysics Data System (ADS)

Adler, Stephen L.; Henneaux, Marc; Pais, Pablo

2017-10-01

We reexamine canonical quantization of the gauged Rarita-Schwinger theory using the extended theory, incorporating a dimension 1/2 auxiliary spin-1/2 field Λ , in which there is an exact off-shell gauge invariance. In Λ =0 gauge, which reduces to the original unextended theory, our results agree with those found by Johnson and Sudarshan, and later verified by Velo and Zwanziger, which give a canonical Rarita-Schwinger field Dirac bracket that is singular for small gauge fields. In gauge covariant radiation gauge, the Dirac bracket of the Rarita-Schwinger fields is nonsingular, but does not correspond to a positive semidefinite anticommutator, and the Dirac bracket of the auxiliary fields has a singularity of the same form as found in the unextended theory. These results indicate that gauged Rarita-Schwinger theory is somewhat pathological, and cannot be canonically quantized within a conventional positive semidefinite metric Hilbert space. We leave open the questions of whether consistent quantizations can be achieved by using an indefinite metric Hilbert space, by path integral methods, or by appropriate couplings to conventional dimension 3/2 spin-1/2 fields.

Scalar field collapse in gauge theory gravity

NASA Astrophysics Data System (ADS)

Harke, Richard Eugene

A brief introduction to gravitational collapse in General Relativity is given. Then critical phenomena in the collapse of a massless scalar field as discovered by Choptuik are described. My own work in this area is described and some results are presented. Gauge Theory Gravity and its mathematical formalism, geometric algebra are introduced. Because geometric algebra is not widely known, a detailed and rigorous introduction to it is provided. The basic principles of Gauge Theory Gravity (GTG) are described and a derivation of the field equations is presented. An appropriate Lagrangian for the scalar field in GTG is introduced and the energy tensor is derived by the usual variational process. The equations of motion for the scalar field are derived for a spherically symmetric space. Finite difference approximations to these equations are constructed and simulations of gravitational collapse are run on a computer. Graphical results are presented. An unexpected phenomenon is found in which the passage of the scalar field leaves a persistent change in the gravitational gauge field.

Large tensor non-Gaussianity from axion-gauge field dynamics

NASA Astrophysics Data System (ADS)

Agrawal, Aniket; Fujita, Tomohiro; Komatsu, Eiichiro

2018-05-01

We show that an inflation model in which a spectator axion field is coupled to an S U (2 ) gauge field produces a large three-point function (bispectrum) of primordial gravitational waves, Bh, on the scales relevant to the cosmic microwave background experiments. The amplitude of the bispectrum at the equilateral configuration is characterized by Bh/Ph2=O (10 )×ΩA-1 , where ΩA is a fraction of the energy density in the gauge field and Ph is the power spectrum of gravitational waves produced by the gauge field.

Democratic superstring field theory: gauge fixing

NASA Astrophysics Data System (ADS)

Kroyter, Michael

2011-03-01

We show that a partial gauge fixing of the NS sector of the democratic-picture superstring field theory leads to the non-polynomial theory. Moreover, by partially gauge fixing the Ramond sector we obtain a non-polynomial fully RNS theory at pictures 0 and 1/2 . Within the democratic theory and in the partially gauge fixed theory the equations of motion of both sectors are derived from an action. We also discuss a representation of the non-polynomial theory analogous to a manifestly two-dimensional representation of WZW theory and the action of bosonic pure-gauge solutions. We further demonstrate that one can consistently gauge fix the NS sector of the democratic theory at picture number -1. The resulting theory is new. It is a {mathbb{Z}_2} dual of the modified cubic theory. We construct analytical solutions of this theory and show that they possess the desired properties.

Deflection of jets induced by jet-cloud and jet-galaxy interactions

NASA Astrophysics Data System (ADS)

Mendoza, S.; Longair, M. S.

2001-06-01

The model first introduced by Raga & Cantó in which astrophysical jets are deflected on passing through an isothermal high-density region is generalized by taking into account gravitational effects on the motion of the jet as it crosses the high-density cloud. The problem is also generalized for relativistic jets in which gravitational effects induced by the cloud are neglected. Two further cases, classical and relativistic, are discussed for the cases in which the jet is deflected on passing through the interstellar gas of a galaxy in which a dark matter halo dominates the gravitational potential. The criteria for the stability of jets due to the formation of internal shocks are also discussed.

Interaction of non-Abelian tensor gauge fields

NASA Astrophysics Data System (ADS)

Savvidy, George

2018-01-01

The non-Abelian tensor gauge fields take value in extended Poincaré algebra. In order to define the invariant Lagrangian we introduce a vector variable in two alternative ways: through the transversal representation of the extended Poincaré algebra and through the path integral over the auxiliary vector field with the U(1) Abelian action. We demonstrate that this allows to fix the unitary gauge and derive scattering amplitudes in spinor representation.

Tensor non-Gaussianity from axion-gauge-fields dynamics: parameter search

NASA Astrophysics Data System (ADS)

Agrawal, Aniket; Fujita, Tomohiro; Komatsu, Eiichiro

2018-06-01

We calculate the bispectrum of scale-invariant tensor modes sourced by spectator SU(2) gauge fields during inflation in a model containing a scalar inflaton, a pseudoscalar axion and SU(2) gauge fields. A large bispectrum is generated in this model at tree-level as the gauge fields contain a tensor degree of freedom, and its production is dominated by self-coupling of the gauge fields. This is a unique feature of non-Abelian gauge theory. The shape of the tensor bispectrum is approximately an equilateral shape for 3lesssim mQlesssim 4, where mQ is an effective dimensionless mass of the SU(2) field normalised by the Hubble expansion rate during inflation. The amplitude of non-Gaussianity of the tensor modes, characterised by the ratio Bh/P2h, is inversely proportional to the energy density fraction of the gauge field. This ratio can be much greater than unity, whereas the ratio from the vacuum fluctuation of the metric is of order unity. The bispectrum is effective at constraining large mQ regions of the parameter space, whereas the power spectrum constrains small mQ regions.

Cartan gravity, matter fields, and the gauge principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westman, Hans F., E-mail: hwestman74@gmail.com; Zlosnik, Tom G., E-mail: t.zlosnik@imperial.ac.uk

Gravity is commonly thought of as one of the four force fields in nature. However, in standard formulations its mathematical structure is rather different from the Yang–Mills fields of particle physics that govern the electromagnetic, weak, and strong interactions. This paper explores this dissonance with particular focus on how gravity couples to matter from the perspective of the Cartan-geometric formulation of gravity. There the gravitational field is represented by a pair of variables: (1) a ‘contact vector’ V{sup A} which is geometrically visualized as the contact point between the spacetime manifold and a model spacetime being ‘rolled’ on top ofmore » it, and (2) a gauge connection A{sub μ}{sup AB}, here taken to be valued in the Lie algebra of SO(2,3) or SO(1,4), which mathematically determines how much the model spacetime is rotated when rolled. By insisting on two principles, the gauge principle and polynomial simplicity, we shall show how one can reformulate matter field actions in a way that is harmonious with Cartan’s geometric construction. This yields a formulation of all matter fields in terms of first order partial differential equations. We show in detail how the standard second order formulation can be recovered. In particular, the Hodge dual, which characterizes the structure of bosonic field equations, pops up automatically. Furthermore, the energy–momentum and spin-density three-forms are naturally combined into a single object here denoted the spin-energy–momentum three-form. Finally, we highlight a peculiarity in the mathematical structure of our first-order formulation of Yang–Mills fields. This suggests a way to unify a U(1) gauge field with gravity into a SO(1,5)-valued gauge field using a natural generalization of Cartan geometry in which the larger symmetry group is spontaneously broken down to SO(1,3)×U(1). The coupling of this unified theory to matter fields and possible extensions to non-Abelian gauge fields are

Emergent kink stability of a magnetized plasma jet injected into a transverse background magnetic field

NASA Astrophysics Data System (ADS)

Zhang, Yue; Gilmore, Mark; Hsu, Scott C.; Fisher, Dustin M.; Lynn, Alan G.

2017-11-01

We report experimental results on the injection of a magnetized plasma jet into a transverse background magnetic field in the HelCat linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys. 81(1), 345810104 (2015)]. After the plasma jet leaves the plasma-gun muzzle, a tension force arising from an increasing curvature of the background magnetic field induces in the jet a sheared axial-flow gradient above the theoretical kink-stabilization threshold. We observe that this emergent sheared axial flow stabilizes the n = 1 kink mode in the jet, whereas a kink instability is observed in the jet when there is no background magnetic field present.

Gauge Field Localization on Deformed Branes

NASA Astrophysics Data System (ADS)

Tofighi, A.; Moazzen, M.; Farokhtabar, A.

2016-02-01

In this paper, we utilise the Chumbes-Holf da Silva-Hott (CHH) mechanism to investigate the issue of gauge field localization on a deformed brane constructed with one scalar field, which can be coupled to gravity minimally or non-minimally. The study of deformed defects is important because they contain internal structures which may have implications in braneworld models. With the CHH mechanism, we find that the massless zero mode of gauge field, in the case of minimal or non-minimal coupling is localized on the brane. Moreover, in the case of non-minimal coupling, it is shown that, when the non-minimal coupling constant is larger than its critical value, then the zero mode is localized on each sub brane.

Gauge fields and inflation

NASA Astrophysics Data System (ADS)

Maleknejad, A.; Sheikh-Jabbari, M. M.; Soda, J.

2013-07-01

The isotropy and homogeneity of the cosmic microwave background (CMB) favors “scalar driven” early Universe inflationary models. However, gauge fields and other non-scalar fields are far more common at all energy scales, in particular at high energies seemingly relevant to inflation models. Hence, in this review we consider the role and consequences, theoretical and observational, that gauge fields can have during the inflationary era. Gauge fields may be turned on in the background during inflation, or may become relevant at the level of cosmic perturbations. There have been two main classes of models with gauge fields in the background, models which show violation of the cosmic no-hair theorem and those which lead to isotropic FLRW cosmology, respecting the cosmic no-hair theorem. Models in which gauge fields are only turned on at the cosmic perturbation level, may source primordial magnetic fields. We also review specific observational features of these models on the CMB and/or the primordial cosmic magnetic fields. Our discussions will be mainly focused on the inflation period, with only a brief discussion on the post inflationary (p)reheating era. Large field models: The initial value of the inflaton field is large, generically super-Planckian, and it rolls slowly down toward the potential minimum at smaller φ values. For instance, chaotic inflation is one of the representative models of this class. The typical potential of large-field models has a monomial form as V(φ)=V0φn. A simple analysis using the dynamical equations reveals that for number of e-folds Ne larger than 60, we require super-Planckian initial field values,5φ0>3M. For these models typically ɛ˜η˜Ne-1. Small field models: Inflaton field is initially small and slowly evolves toward the potential minimum at larger φ values. The small field models are characterized by the following potential V(φ)=V0(1-(), which corresponds to a Taylor expansion about the origin, but more realistic

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Yep, Tze-Wing; Agrawal, Ajay K.; Griffin, DeVon; Salzman, Jack (Technical Monitor)

2001-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2-second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet flow was significantly influenced by the gravity. The jet in microgravity was up to 70 percent wider than that in Earth gravity. The jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes a change in gravity in the drop tower.

Comparison of characteristics and downstream uniformity of linear-field and cross-field atmospheric pressure plasma jet array in He

NASA Astrophysics Data System (ADS)

Zhang, Bo; Fang, Zhi; Liu, Feng; Zhou, Renwu; Zhou, Ruoyu

2018-06-01

Using an atmospheric pressure plasma jet array is an effective way for expanding the treatment area of a single jet, and generating arrays with well downstream uniformity is of great interest for its applications. In this paper, a plasma jet array in helium is generated in a linear-field jet array with a ring-ring electrode structure excited by alternating current. The characteristics and downstream uniformity of the array and their dependence on the applied voltage and gas flow rate are investigated through optical, electrical, and Schlieren diagnostics. The results are compared with those of our reported work of a cross-field jet array with a needle-ring electrode structure. The results show that the linear-field jet array can generate relatively large-scale plasma with better uniformity and longer plumes than the cross-field case. The divergences observed in gas channels and the plasma plume trajectories are much less than those of the cross-field one. The deflection angle of lateral plumes is less than 6°, which is independent of the gas flow rate and applied voltage. The maximum downstream plumes of 23 mm can be obtained at 7 kV peak applied voltage and 4 l/min gas flow rate. The better uniformity of linear-field jet arrays is due to the effective suppression of hydrodynamic and electrical interactions among the jets in the arrays with a more uniform electric field distribution. The hydrodynamic interaction induced by the gas heating in the linear-field jet array is less than that of the cross-field one. The more uniform electric field distribution in the linear-field jet arrays can reduce the divergence of the propagation trajectories of the plasma plumes. It will generate less residual charge between the adjacent discharges and thus can reduce the accumulation effect of Coulomb force between the plasma plumes. The reported results can help design controllable and scalable plasma jet arrays with well uniformity for material surface and biomedical treatments.

Cartan gravity, matter fields, and the gauge principle

NASA Astrophysics Data System (ADS)

Westman, Hans F.; Zlosnik, Tom G.

2013-07-01

Gravity is commonly thought of as one of the four force fields in nature. However, in standard formulations its mathematical structure is rather different from the Yang-Mills fields of particle physics that govern the electromagnetic, weak, and strong interactions. This paper explores this dissonance with particular focus on how gravity couples to matter from the perspective of the Cartan-geometric formulation of gravity. There the gravitational field is represented by a pair of variables: (1) a 'contact vector' VA which is geometrically visualized as the contact point between the spacetime manifold and a model spacetime being 'rolled' on top of it, and (2) a gauge connection AμAB, here taken to be valued in the Lie algebra of SO(2,3) or SO(1,4), which mathematically determines how much the model spacetime is rotated when rolled. By insisting on two principles, the gauge principle and polynomial simplicity, we shall show how one can reformulate matter field actions in a way that is harmonious with Cartan's geometric construction. This yields a formulation of all matter fields in terms of first order partial differential equations. We show in detail how the standard second order formulation can be recovered. In particular, the Hodge dual, which characterizes the structure of bosonic field equations, pops up automatically. Furthermore, the energy-momentum and spin-density three-forms are naturally combined into a single object here denoted the spin-energy-momentum three-form. Finally, we highlight a peculiarity in the mathematical structure of our first-order formulation of Yang-Mills fields. This suggests a way to unify a U(1) gauge field with gravity into a SO(1,5)-valued gauge field using a natural generalization of Cartan geometry in which the larger symmetry group is spontaneously broken down to SO(1,3)×U(1). The coupling of this unified theory to matter fields and possible extensions to non-Abelian gauge fields are left as open questions.

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Griffin, D. W.; Yep, T. W.; Agrawal, A. K.

2005-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2- second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet in microgravity was up to 70 percent wider than that in Earth gravity. The global jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes change in gravity in the drop tower.

Adiabatic regularization for gauge fields and the conformal anomaly

NASA Astrophysics Data System (ADS)

Chu, Chong-Sun; Koyama, Yoji

2017-03-01

Adiabatic regularization for quantum field theory in conformally flat spacetime is known for scalar and Dirac fermion fields. In this paper, we complete the construction by establishing the adiabatic regularization scheme for the gauge field. We show that the adiabatic expansion for the mode functions and the adiabatic vacuum can be defined in a similar way using Wentzel-Kramers-Brillouin-type (WKB-type) solutions as the scalar fields. As an application of the adiabatic method, we compute the trace of the energy momentum tensor and reproduce the known result for the conformal anomaly obtained by the other regularization methods. The availability of the adiabatic expansion scheme for the gauge field allows one to study various renormalized physical quantities of theories coupled to (non-Abelian) gauge fields in conformally flat spacetime, such as conformal supersymmetric Yang Mills, inflation, and cosmology.

Synthetic Jet Flow Field Database for CFD Validation

NASA Technical Reports Server (NTRS)

Yao, Chung-Sheng; Chen, Fang Jenq; Neuhart, Dan; Harris, Jerome

2004-01-01

An oscillatory zero net mass flow jet was generated by a cavity-pumping device, namely a synthetic jet actuator. This basic oscillating jet flow field was selected as the first of the three test cases for the Langley workshop on CFD Validation of Synthetic Jets and Turbulent Separation Control. The purpose of this workshop was to assess the current CFD capabilities to predict unsteady flow fields of synthetic jets and separation control. This paper describes the characteristics and flow field database of a synthetic jet in a quiescent fluid. In this experiment, Particle Image Velocimetry (PIV), Laser Doppler Velocimetry (LDV), and hot-wire anemometry were used to measure the jet velocity field. In addition, the actuator operating parameters including diaphragm displacement, internal cavity pressure, and internal cavity temperature were also documented to provide boundary conditions for CFD modeling.

Recurrent coronal jets induced by repetitively accumulated electric currents

NASA Astrophysics Data System (ADS)

Guo, Y.; Démoulin, P.; Schmieder, B.; Ding, M. D.; Vargas Domínguez, S.; Liu, Y.

2013-07-01

periodically, in the current layer created between the emerging bipoles and the large-scale active region field. The periodic magnetic reconnection induced the observed recurrent coronal jets and the decrease of the vertical electric current magnitude. Two movies are available in electronic form at http://www.aanda.org

Multigrid Methods for the Computation of Propagators in Gauge Fields

NASA Astrophysics Data System (ADS)

Kalkreuter, Thomas

Multigrid methods were invented for the solution of discretized partial differential equations in order to overcome the slowness of traditional algorithms by updates on various length scales. In the present work generalizations of multigrid methods for propagators in gauge fields are investigated. Gauge fields are incorporated in algorithms in a covariant way. The kernel C of the restriction operator which averages from one grid to the next coarser grid is defined by projection on the ground-state of a local Hamiltonian. The idea behind this definition is that the appropriate notion of smoothness depends on the dynamics. The ground-state projection choice of C can be used in arbitrary dimension and for arbitrary gauge group. We discuss proper averaging operations for bosons and for staggered fermions. The kernels C can also be used in multigrid Monte Carlo simulations, and for the definition of block spins and blocked gauge fields in Monte Carlo renormalization group studies. Actual numerical computations are performed in four-dimensional SU(2) gauge fields. We prove that our proposals for block spins are “good”, using renormalization group arguments. A central result is that the multigrid method works in arbitrarily disordered gauge fields, in principle. It is proved that computations of propagators in gauge fields without critical slowing down are possible when one uses an ideal interpolation kernel. Unfortunately, the idealized algorithm is not practical, but it was important to answer questions of principle. Practical methods are able to outperform the conjugate gradient algorithm in case of bosons. The case of staggered fermions is harder. Multigrid methods give considerable speed-ups compared to conventional relaxation algorithms, but on lattices up to 184 conjugate gradient is superior.

Quantization of gauge fields, graph polynomials and graph homology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreimer, Dirk, E-mail: kreimer@physik.hu-berlin.de; Sars, Matthias; Suijlekom, Walter D. van

2013-09-15

We review quantization of gauge fields using algebraic properties of 3-regular graphs. We derive the Feynman integrand at n loops for a non-abelian gauge theory quantized in a covariant gauge from scalar integrands for connected 3-regular graphs, obtained from the two Symanzik polynomials. The transition to the full gauge theory amplitude is obtained by the use of a third, new, graph polynomial, the corolla polynomial. This implies effectively a covariant quantization without ghosts, where all the relevant signs of the ghost sector are incorporated in a double complex furnished by the corolla polynomial–we call it cycle homology–and by graph homology.more » -- Highlights: •We derive gauge theory Feynman from scalar field theory with 3-valent vertices. •We clarify the role of graph homology and cycle homology. •We use parametric renormalization and the new corolla polynomial.« less

Exploring the jet multiplicity in the 750 GeV diphoton excess

DOE PAGES

Dalchenko, Mykhailo; Dutta, Bhaskar; Gao, Yu; ...

2016-10-01

The recent diphoton excess at the LHC has been explained tentatively by a Standard Model (SM) singlet scalar of 750 GeV in mass, in the association of heavy particles with SM gauge charges. These new particles with various SM gauge charges induce loop-level couplings of the new scalar to WW, ZZ, Zγ, γγ, and gg. Here, we show that the strength of the couplings to the gauge bosons also determines the production mechanism of the scalar particle via WW,ZZ,Zγ,γγ,gg fusion which leads to individually distinguishable jet distributions in the final state where the statistics will be improved in the ongoingmore » run. Finally, the number of jets and the leading jet's transverse momentum distribution in the excess region of the diphoton signal can be used to determine the coupling of the scalar to the gauge bosons arising from the protons which subsequently determine the charges of the heavy particles that arise from various well-motivated models.« less

Gravitational waves from non-Abelian gauge fields at a tachyonic transition

NASA Astrophysics Data System (ADS)

Tranberg, Anders; Tähtinen, Sara; Weir, David J.

2018-04-01

We compute the gravitational wave spectrum from a tachyonic preheating transition of a Standard Model-like SU(2)-Higgs system. Tachyonic preheating involves exponentially growing IR modes, at scales as large as the horizon. Such a transition at the electroweak scale could be detectable by LISA, if these non-perturbatively large modes translate into non-linear dynamics sourcing gravitational waves. Through large-scale numerical simulations, we find that the spectrum of gravitational waves does not exhibit such IR features. Instead, we find two peaks corresponding to the Higgs and gauge field mass, respectively. We find that the gravitational wave production is reduced when adding non-Abelian gauge fields to a scalar-only theory, but increases when adding Abelian gauge fields. In particular, gauge fields suppress the gravitational wave spectrum in the IR. A tachyonic transition in the early Universe will therefore not be detectable by LISA, even if it involves non-Abelian gauge fields.

Magnetic field, reconnection, and particle acceleration in extragalactic jets

NASA Technical Reports Server (NTRS)

Romanova, M. M.; Lovelace, R. V. E.

1992-01-01

Extra-galactic radio jets are investigated theoretically taking into account that the jet magnetic field is dragged out from the central rotating source by the jet flow. Thus, magnetohydrodynamic models of jets are considered with zero net poloidal current and flux, and consequently a predominantly toroidal magnetic field. The magnetic field naturally has a cylindrical neutral layer. Collisionless reconnection of the magnetic field in the vicinity of the neutral layer acts to generate a non-axisymmetric radial magnetic field. In turn, axial shear-stretching of reconnected toroidal field gives rise to a significant axial magnetic field if the flow energy-density is larger than the energy-density of the magnetic field. This can lead to jets with an apparent longitudinal magnetic field as observed in the Fanaroff-Riley class II jets. In the opposite limit, where the field energy-density is large, the field remains mainly toroidal as observed in Fanaroff-Riley class I jets. Driven collisionless reconnection at neutral layers may lead to acceleration of electrons to relativistic energies in the weak electrostatic field of the neutral layer. A simple model is discussed for particle acceleration at neutral layers in electron/positron and electron/proton plasmas.

Unveiling a spinor field classification with non-Abelian gauge symmetries

NASA Astrophysics Data System (ADS)

Fabbri, Luca; da Rocha, Roldão

2018-05-01

A spinor fields classification with non-Abelian gauge symmetries is introduced, generalizing the U(1) gauge symmetries-based Lounesto's classification. Here, a more general classification, contrary to the Lounesto's one, encompasses spinor multiplets, corresponding to non-Abelian gauge fields. The particular case of SU(2) gauge symmetry, encompassing electroweak and electromagnetic conserved charges, is then implemented by a non-Abelian spinor classification, now involving 14 mixed classes of spinor doublets. A richer flagpole, dipole, and flag-dipole structure naturally descends from this general classification. The Lounesto's classification of spinors is shown to arise as a Pauli's singlet, into this more general classification.

Wormholes, emergent gauge fields, and the weak gravity conjecture

DOE PAGES

Harlow, Daniel

2016-01-20

This paper revisits the question of reconstructing bulk gauge fields as boundary operators in AdS/CFT. In the presence of the ormhole dual to the thermo field double state of two CFTs, the existence of bulk gauge fields is in some tension with the microscopic tensor factorization of the Hilbert space. Here, I explain how this tension can be resolved by splitting the gauge field into charged constituents, and I argue that this leads to a new argument for the "principle of completeness", which states that the charge lattice of a gauge theory coupled to gravity must be fully populated. Imore » also claim that it leads to a new motivation for (and a clarification of) the "weak gravity conjecture", which I interpret as a strengthening of this principle. This setup gives a simple example of a situation where describing low-energy bulk physics in CFT language requires knowledge of high-energy bulk physics. Furthermore, this contradicts to some extent the notion of "effective conformal field theory", but in fact is an expected feature of the resolution of the black hole information problem. An analogous factorization issue exists also for the gravitational field, and I comment on several of its implications for reconstructing black hole interiors and the emergence of spacetime more generally.« less

Bead-on-string structure printed by electrohydrodynamic jet under alternating current electric field

NASA Astrophysics Data System (ADS)

Liu, Juan; Lin, Yihuang; Jiang, Jiaxin; Liu, Haiyan; Zhao, Yang; Zheng, Gaofeng

2016-09-01

Electrohydrodynamic printing (EHDP) under alternating current (AC) electric field provides a novel way for the precise micro-/nano-droplet printing. The AC electric field induces the free charge to reciprocate along the EHDP jet and changes the electric field force on the jet periodically. The stability of jet can be enhanced by increasing the voltage frequency, and the regular bead-on-string structure is direct-written along the trajectory of collector. The deposition frequency of bead structure increases with the increasing of voltage frequency, due to the short period of AC electric field. As the voltage frequency is increased from 10 to 60 Hz, the diameter of bead structure decreases from 200 to 110 µm. As the duty ration increased from 10 to 60 %, the diameter of bead structure increased from 100 to 140 µm. This work would accelerate the development and the application of micro-/nano-printing technology in the fields of flexible electronic and micro-/nano-system.

Exciting gauge field and gravitons in brane-antibrane annihilation.

PubMed

Mazumdar, Anupam; Stoica, Horace

2009-03-06

In this Letter we point out the inevitability of an explosive production of gauge field and gravity wave during an open string tachyon condensation in a cosmological setting, in an effective field theory model. We will be particularly studying a toy model of brane-antibrane inflation in a warped throat where inflation ends via tachyon condensation. We point out that a tachyonic instability helps fragmenting the homogeneous tachyon and excites gauge field and contributes to the stress-energy tensor which also feeds into the gravity waves.

Gauge invariant fractional electromagnetic fields

NASA Astrophysics Data System (ADS)

Lazo, Matheus Jatkoske

2011-09-01

Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators.

Gauge field localization on brane worlds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guerrero, Rommel; Rodriguez, R. Omar; Melfo, Alejandra

2010-04-15

We consider the effects of spacetime curvature and brane thickness on the localization of gauge fields on a brane via kinetic terms induced by localized fermions. We find that in a warped geometry with an infinitely thin brane, both the infrared and the ultraviolet behavior of the electromagnetic propagator are affected, providing a more stringent bound on the brane's tension than that coming from the requirement of four-dimensional gravity on the brane. On the other hand, for a thick wall in a flat spacetime, where the fermions are localized by means of a Yukawa coupling, we find that four-dimensional electromagnetismmore » is recovered in a region bounded from above by the same critical distance appearing in the thin case, but also from below by a new scale related to the brane's thickness and the electromagnetic couplings. This imposes very stringent bounds on the brane's thickness which seem to invalidate the localization mechanism for this case.« less

Gauge-invariant expectation values of the energy of a molecule in an electromagnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandal, Anirban; Hunt, Katharine L. C.

In this paper, we show that the full Hamiltonian for a molecule in an electromagnetic field can be separated into a molecular Hamiltonian and a field Hamiltonian, both with gauge-invariant expectation values. The expectation value of the molecular Hamiltonian gives physically meaningful results for the energy of a molecule in a time-dependent applied field. In contrast, the usual partitioning of the full Hamiltonian into molecular and field terms introduces an arbitrary gauge-dependent potential into the molecular Hamiltonian and leaves a gauge-dependent form of the Hamiltonian for the field. With the usual partitioning of the Hamiltonian, this same problem of gaugemore » dependence arises even in the absence of an applied field, as we show explicitly by considering a gauge transformation from zero applied field and zero external potentials to zero applied field, but non-zero external vector and scalar potentials. We resolve this problem and also remove the gauge dependence from the Hamiltonian for a molecule in a non-zero applied field and from the field Hamiltonian, by repartitioning the full Hamiltonian. It is possible to remove the gauge dependence because the interaction of the molecular charges with the gauge potential cancels identically with a gauge-dependent term in the usual form of the field Hamiltonian. We treat the electromagnetic field classically and treat the molecule quantum mechanically, but nonrelativistically. Our derivation starts from the Lagrangian for a set of charged particles and an electromagnetic field, with the particle coordinates, the vector potential, the scalar potential, and their time derivatives treated as the variables in the Lagrangian. We construct the full Hamiltonian using a Lagrange multiplier method originally suggested by Dirac, partition this Hamiltonian into a molecular term H{sub m} and a field term H{sub f}, and show that both H{sub m} and H{sub f} have gauge-independent expectation values. Any gauge may be chosen

Near-field acoustical holography of military jet aircraft noise

NASA Astrophysics Data System (ADS)

Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

2010-10-01

Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

Emergent gauge field for a chiral bound state on curved surface

NASA Astrophysics Data System (ADS)

Shi, Zhe-Yu; Zhai, Hui

2017-09-01

Emergent physics is one of the most important concepts in modern physics, and one of the most intriguing examples is the emergent gauge field. Here we show that a gauge field emerges for a chiral bound state formed by two attractively interacting particles on a curved surface. We demonstrate explicitly that the center-of-mass wave function of such a deeply bound state is monopole harmonic instead of spherical harmonic, which means that the bound state experiences a magnetic monopole at the center of the sphere. This emergent gauge field is due to the coupling between the center-of-mass and the relative motion on a curved surface, and our results can be generalized to an arbitrary curved surface. This result establishes an intriguing connection between the space curvature and gauge field, and paves an alternative way to engineer a topological state with space curvature, and may be observed in a cold atom system.

Gauge-independent decoherence models for solids in external fields

NASA Astrophysics Data System (ADS)

Wismer, Michael S.; Yakovlev, Vladislav S.

2018-04-01

We demonstrate gauge-invariant modeling of an open system of electrons in a periodic potential interacting with an optical field. For this purpose, we adapt the covariant derivative to the case of mixed states and put forward a decoherence model that has simple analytical forms in the length and velocity gauges. We demonstrate our methods by calculating harmonic spectra in the strong-field regime and numerically verifying the equivalence of the deterministic master equation to the stochastic Monte Carlo wave-function method.

Toward a gauge field theory of gravity.

NASA Astrophysics Data System (ADS)

Yilmaz, H.

Joint use of two differential identities (Bianchi and Freud) permits a gauge field theory of gravity in which the gravitational energy is localizable. The theory is compatible with quantum mechanics and is experimentally viable.

Dynamics of Plasma Jets and Bubbles Launched into a Transverse Background Magnetic Field

NASA Astrophysics Data System (ADS)

Zhang, Yue

2017-10-01

A coaxial magnetized plasma gun has been utilized to launch both plasma jets (open B-field) and plasma bubbles (closed B-field) into a transverse background magnetic field in the HelCat (Helicon-Cathode) linear device at the University of New Mexico. These situations may have bearing on fusion plasmas (e.g. plasma injection for tokamak fueling, ELM pacing, or disruption mitigation) and astrophysical settings (e.g. astrophysical jet stability, coronal mass ejections, etc.). The magnetic Reynolds number of the gun plasma is 100 , so that magnetic advection dominates over magnetic diffusion. The gun plasma ram pressure, ρjetVjet2 >B02 / 2μ0 , the background magnetic pressure, so that the jet or bubble can easily penetrate the background B-field, B0. When the gun axial B-field is weak compared to the gun azimuthal field, a current-driven jet is formed with a global helical magnetic configuration. Applying the transverse background magnetic field, it is observed that the n = 1 kink mode is stabilized, while magnetic probe measurements show contrarily that the safety factor q(a) drops below unity. At the same time, a sheared axial jet velocity is measured. We conclude that the tension force arising from increasing curvature of the background magnetic field induces the measured sheared flow gradient above the theoretical kink-stabilization threshold, resulting in the emergent kink stabilization of the injected plasma jet. In the case of injected bubbles, spheromak-like plasma formation is verified. However, when the spheromak plasma propagates into the transverse background magnetic field, the typical self-closed global symmetry magnetic configuration does not hold any more. In the region where the bubble toroidal field opposed the background B-field, the magneto-Rayleigh-Taylor (MRT) instability has been observed. Details of the experiment setup, diagnostics, experimental results and theoretical analysis will be presented. Supported by the National Science Foundation

Photonic modes in synthetic photonic lattices localized due to nontrivial gauge field circulation

NASA Astrophysics Data System (ADS)

Pankov, Artem; Vatnik, Ilya; Churkin, Dmitry; Sukhorukov, Andrey A.

2017-10-01

One of concepts giving opportunities for studying of topological insulators in non-magnetic materials, or creating scattering-immune in optical waveguides is creation of synthetic gauge fields in photonic systems. It was shown that gauge fields shift the band-gaps of optical waves, which can be applied to implement one-way nonreciprocal waveguides, even though both the waveguide core and cladding are in a topologically trivial state [1]. In our work we propose a method to create a gauge field in a synthetic photonic mesh lattice - an optical device proved its high versatility for optical experiments [2]. We demonstrate presence of localized modes due to nontrivial gauge field circulation.

Polarization-dependent optics using gauge-field metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Fu; Xiao, Shiyi; Li, Jensen, E-mail: j.li@bham.ac.uk

2015-12-14

We show that effective gauge field for photons with polarization-split dispersion surfaces, being realized using uniaxial metamaterials, can be used for polarization control with unique opportunities. The metamaterials with the proposed gauge field correspond to a special choice of eigenpolarizations on the Poincaré sphere as pseudo-spins, in contrary to those from either conventional birefringent crystals or optical active media. It gives rise to all-angle polarization control and a generic route to manipulate photon trajectories or polarizations in the pseudo-spin domain. As demonstrations, we show beam splitting (birefringent polarizer), all-angle polarization control, unidirectional polarization filter, and interferometer as various polarization controlmore » devices in the pseudo-spin domain. We expect that more polarization-dependent devices can be designed under the same framework.« less

Primordial anisotropies in gauged hybrid inflation

NASA Astrophysics Data System (ADS)

Akbar Abolhasani, Ali; Emami, Razieh; Firouzjahi, Hassan

2014-05-01

We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations.

Elastic gauge fields and Hall viscosity of Dirac magnons

NASA Astrophysics Data System (ADS)

Ferreiros, Yago; Vozmediano, María A. H.

2018-02-01

We analyze the coupling of elastic lattice deformations to the magnon degrees of freedom of magnon Dirac materials. For a honeycomb ferromagnet we find that, as happens in the case of graphene, elastic gauge fields appear coupled to the magnon pseudospinors. For deformations that induce constant pseudomagnetic fields, the spectrum around the Dirac nodes splits into pseudo-Landau levels. We show that when a Dzyaloshinskii-Moriya interaction is considered, a topological gap opens in the system and a Chern-Simons effective action for the elastic degrees of freedom is generated. Such a term encodes a phonon Hall viscosity response, entirely generated by quantum fluctuations of magnons living in the vicinity of the Dirac points. The magnon Hall viscosity vanishes at zero temperature, and grows as temperature is raised and the states around the Dirac points are increasingly populated.

Calculating the jet quenching parameter in the plasma of noncommutative Yang-Mills theory from gauge/gravity duality

NASA Astrophysics Data System (ADS)

Chakraborty, Somdeb; Roy, Shibaji

2012-02-01

A particular decoupling limit of the nonextremal (D1, D3) brane bound state system of type IIB string theory is known to give the gravity dual of space-space noncommutative Yang-Mills theory at finite temperature. We use a string probe in this background to compute the jet quenching parameter in a strongly coupled plasma of hot noncommutative Yang-Mills theory in (3+1) dimensions from gauge/gravity duality. We give expressions for the jet quenching parameter for both small and large noncommutativity. For small noncommutativity, we find that the value of the jet quenching parameter gets reduced from its commutative value. The reduction is enhanced with temperature as T7 for fixed noncommutativity and fixed ’t Hooft coupling. We also give an estimate of the correction due to noncommutativity at the present collider energies like in RHIC or in LHC and find it too small to be detected. We further generalize the results for noncommutative Yang-Mills theories in diverse dimensions.

Poynting Robertson Battery and the Chiral Magnetic Fields of AGN Jets

NASA Technical Reports Server (NTRS)

Kazanas, Demosthenes

2010-01-01

We propose that the magnetic fields in the accretion disks of active galactic nuclei (AGNs) are generated by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with the AGN photons (the Poynting Robertson battery). This process provides a unique relation between the polarity of the poloidal B field to the angular velocity Omega of the accretion disk (B is parallel to Omega), a relation absent in the more popular dynamo B-field generation. This then leads to a unique direction for the toroidal B field induced by disk rotation. Observations of the toroidal fields of 29 AGN jets revealed by parsec-scale Faraday rotation measurements show a clear asymmetry that is consistent with this model, with the probability that this asymmetry comes about by chance being approx.0.06 %. This lends support to the hypothesis that the universe is seeded by B fields that are generated in AGNs via this mechanism and subsequently injected into intergalactic space by the jet outflows.

Enhancement of convective heat transfer in internal flows using an electrically-induced corona jet

NASA Astrophysics Data System (ADS)

Baghaei Lakeh, Reza

The enhancement of heat transfer by active and passive methods has been the subject of many academic and industrial research studies. Internal flows play a major role in many applications and different methods have been utilized to augment the heat transfer to internal flows. Secondary flows consume part of the kinetic energy of the flow and disturb the boundary layer. Inducing secondary flows is known as mechanism for heat transfer enhancement. Secondary flows may be generated by corona discharge and ion-driven flows. When a high electric potential is applied to a conductor, a high electric field will be generated. The high electric field may exceed the partial break-down of the neutral molecules of surrounding gas (air) and generate a low-temperature plasma in the vicinity of the conductor. The generated plasma acts as a source of ions that accelerate under the influence of the electric field and escape beyond the plasma region and move toward the grounded electrode. The accelerating ions collide with neutral particles of the surrounding gas and impose a dragging effect which is interpreted as a body-force to the air particles. The shape and configuration of the emitting and receiving electrodes has a significant impact on the distribution of the electric body-force and the resulting electrically-induced flow field. It turned out that the certain configurations of longitudinal electrodes may cause a jet-like secondary flow field on the cross section of the flow passage in internal flows. The impingement effect of the corona jet on the walls of the channel disturbs the boundary layer, enhances the convective heat transfer, and generates targeted cooling along the centerline of the jet. The results of the current study show that the concentric configuration of a suspended wire-electrode in a circular tube leads to a hydrostatic condition and do not develop any electrically-induced secondary flow; however, the eccentric wire-electrode configuration generates a

Induced velocity field of a jet in a crossflow

NASA Technical Reports Server (NTRS)

Fearn, R. L.; Weston, R. P.

1978-01-01

An experimental investigation of a subsonic round jet exhausting perpendicularly from a flat plate into a subsonic crosswind of the same temperature was conducted. Velocity and pressure measurements were made in planes perpendicular to the path of the jet for ratios of jet velocity to crossflow velocity ranging from 3 to 10. The results of these measurements are presented in tabular and graphical forms. A pair of diffuse contrarotating vortices is identified as a significant feature of the flow, and the characteristics of the vortices are discussed.

Exploration of discrepancy between radar and gauge rainfall estimates driven by wind fields

NASA Astrophysics Data System (ADS)

Dai, Qiang; Han, Dawei

2014-11-01

Due to the fact that weather radar is prone to several sources of errors, it is acknowledged that adjustment against ground observations such as rain gauges is crucial for radar measurement. Spatial matching of precipitation patterns between radar and rain gauge is a significant premise in radar bias corrections. It is a conventional way to construct radar-gauge pairs based on their vertical locations. However, due to the wind effects, the raindrops observed by the radar do not always fall vertically to the ground, and the raindrops arriving at the ground may not all be caught by the rain gauge. This study proposes a fully formulated scheme to numerically simulate the movement of raindrops in a three-dimensional wind field in order to adjust the wind-induced errors. The Brue catchment (135 km2) in Southwest England covering 28 radar pixels and 49 rain gauges is an experimental catchment, where the radar central beam height varies between 500 and 700 m. The 20 typical events (with durations of 6-36 h) are chosen to assess the correlation between hourly radar and gauge rainfall surfaces. It is found that for most events, the improved rates of correlation coefficients are greater than 10%, and nearly half of the events increase by 20%. With the proposed method, except four events, all the event-averaged correlation values are greater than 0.5. This work is the first study to tackle both wind effects on radar and rain gauges, which could be considered as one of the essential components in processing radar observational data in its hydrometeorological applications.

A simple example of a classical gauge transformation

NASA Technical Reports Server (NTRS)

Whitten, R. C.

1983-01-01

Attention is given to the manner in which the interaction of a gravitational field with a diffusing gas is induced by a gauge transformation. Since the gas can be thought of as a field, the diffusion process may be represented by a Lagrangian density with the symmetry property of invariance under translation. While this property is lost when the field interacts with a static gravitational field, it is formally restored when an appropriate gauge transformation is performed. This ascription of field properties to a gas offers an illuminating illustration of the coupling of matter to a gauge field within the context of classical mechanics.

Resonant ion acceleration by plasma jets: Effects of jet breaking and the magnetic-field curvature.

PubMed

Artemyev, A V; Vasiliev, A A

2015-05-01

In this paper we consider resonant ion acceleration by a plasma jet originating from the magnetic reconnection region. Such jets propagate in the background magnetic field with significantly curved magnetic-field lines. Decoupling of ion and electron motions at the leading edge of the jet results in generation of strong electrostatic fields. Ions can be trapped by this field and get accelerated along the jet front. This mechanism of resonant acceleration resembles surfing acceleration of charged particles at a shock wave. To describe resonant acceleration of ions, we use adiabatic theory of resonant phenomena. We show that particle motion along the curved field lines significantly influences the acceleration rate. The maximum gain of energy is determined by the particle's escape from the system due to this motion. Applications of the proposed mechanism to charged-particle acceleration in the planetary magnetospheres and the solar corona are discussed.

Experimental studies of shock-induced particle jetting

NASA Astrophysics Data System (ADS)

Xue, Kun; Du, Kaiyuan; Shi, Xiaoliang

2018-05-01

The dispersion of particle rings or shells by a radially divergent shock front trailed by the pressurized gases takes the form of hierarchical particle jetting. Through a semi-two-dimensional configuration, we characterize the evolution of the jetting pattern using the boundary tracking technique. In contrast to the refined filamentary jetting spread induced by the dispersal of soft and ductile flour particles, the hard and brittle quartz sand particles are dispersed into a finger-like branched pattern with much fewer jets. The interplay between the primary and secondary jets suffices to reverse the flour jetting pattern, which by contrast is negligible in the quartz sand jetting. The distinct jetting patterns displayed by the flour and quartz sand particles are related with the distinguishable networks of force chains invoked in two particles which dictate the nucleation of jets.

First Law for fields with Internal Gauge Freedom

NASA Astrophysics Data System (ADS)

Prabhu, Kartik

2016-03-01

We extend the analysis of Iyer and Wald to derive the First Law of blackhole mechanics in the presence of fields charged under an `internal gauge group'. We treat diffeomorphisms and gauge transformations in a unified way by formulating the theory on a principal bundle. The first law then relates the energy and angular momentum at infinity to a potential times charge term at the horizon. The gravitational potential and charge give a notion of temperature and entropy respectively.

Balancing anisotropic curvature with gauge fields in a class of shear-free cosmological models

NASA Astrophysics Data System (ADS)

Thorsrud, Mikjel

2018-05-01

We present a complete list of general relativistic shear-free solutions in a class of anisotropic, spatially homogeneous and orthogonal cosmological models containing a collection of n independent p-form gauge fields, where p\\in\\{0, 1, 2, 3\\} , in addition to standard ΛCDM matter fields modelled as perfect fluids. Here a (collection of) gauge field(s) balances anisotropic spatial curvature on the right-hand side of the shear propagation equation. The result is a class of solutions dynamically equivalent to standard FLRW cosmologies, with an effective curvature constant Keff that depends both on spatial curvature and the energy density of the gauge field(s). In the case of a single gauge field (n  =  1) we show that the only spacetimes that admit such solutions are the LRS Bianchi type III, Bianchi type VI0 and Kantowski–Sachs metric, which are dynamically equivalent to open (Keff<0 ), flat (Keff=0 ) and closed (Keff>0 ) FLRW models, respectively. With a collection of gauge fields (n  >  1) also Bianchi type II admits a shear-free solution (Keff>0 ). We identify the LRS Bianchi type III solution to be the unique shear-free solution with a gauge field Hamiltonian bounded from below in the entire class of models.

Relativistic MHD simulations of collision-induced magnetic dissipation in poynting-flux-dominated jets/outflows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Wei; Li, Hui; Zhang, Bing

We perform 3D relativistic ideal MHD simulations to study the collisions between high-σ (Poynting- ux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting- ux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvenic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. In conclusion, our results give support to the proposed astrophysical models that invoke signi cant magnetic energy dissipation in Poynting- ux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.« less

Relativistic MHD simulations of collision-induced magnetic dissipation in poynting-flux-dominated jets/outflows

DOE PAGES

Deng, Wei; Li, Hui; Zhang, Bing; ...

2015-05-29

We perform 3D relativistic ideal MHD simulations to study the collisions between high-σ (Poynting- ux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting- ux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvenic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. In conclusion, our results give support to the proposed astrophysical models that invoke signi cant magnetic energy dissipation in Poynting- ux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.« less

The Mochi LabJet Experiment for Measurements of Canonical Helicity Injection in a Laboratory Astrophysical Jet

NASA Astrophysics Data System (ADS)

You, Setthivoine; von der Linden, Jens; Sander Lavine, Eric; Carroll, Evan Grant; Card, Alexander; Quinley, Morgan; Azuara-Rosales, Manuel

2018-06-01

The Mochi device is a new pulsed power plasma experiment designed to produce long, collimated, stable, magnetized plasma jets when set up in the LabJet configuration. The LabJet configuration aims to simulate an astrophysical jet in the laboratory by mimicking an accretion disk threaded by a poloidal magnetic field with concentric planar electrodes in front of a solenoidal coil. The unique setup consists of three electrodes, each with azimuthally symmetric gas slits. Two of the electrodes are biased independently with respect to the third electrode to control the radial electric field profile across the poloidal bias magnetic field. This design approximates a shear azimuthal rotation profile in an accretion disk. The azimuthally symmetric gas slits provide a continuously symmetric mass source at the footpoint of the plasma jet, so any azimuthal rotation of the plasma jet is not hindered by a discrete number of gas holes. The initial set of diagnostics consists of current Rogowski coils, voltage probes, magnetic field probe arrays, an interferometer and ion Doppler spectroscopy, supplemented by a fast ion gauge and a retarding grid energy analyzer. The measured parameters of the first plasmas are ∼1022 m‑3, ∼0.4 T, and 5–25 eV, with velocities of ∼20–80 km s‑1. The combination of a controllable electric field profile, a flared poloidal magnetic field, and azimuthally symmetric mass sources in the experiment successfully produces short-lived (∼10 μs, ≳5 Alfvén times) collimated magnetic jets with a ∼10:1 aspect ratio and long-lived (∼100 μs, ≳40 Alfvén times) flow-stabilized, collimated, magnetic jets with a ∼30:1 aspect ratio.

Experimental Study of Impinging Jets Flow-Fields

DTIC Science & Technology

2016-07-27

1 Grant # N000141410830 Experimental Study of Impinging Jet Flow-Fields Final Report for Period: Jun 15, 2014 – Jun 14, 2016 PI: Dennis K...impinging jet model in the absence of any jet heating. The results of the computations had been compared with the experimental data produced in the...of the validity of the computations, and also of the experimental approach. Figure 12a. Initial single

Meso-beta scale numerical simulation studies of terrain-induced jet streak mass/momentum perturbations

NASA Technical Reports Server (NTRS)

Lin, Yuh-Lang; Kaplan, Michael L.

1995-01-01

Mesoscale model simulations provide insight into the complex jet streak adjustments on 11-12 July 1981 that preceded the first of two significant gravity wave events to have been generated over the Rocky Mountains in Montana. Simulations employing a variety of terrain treatments indicate that prior to wave formation, geostrophic adjustment processes modified the structure of the mid-upper tropospheric jet streak by creating secondary jetlets to the southeast of the polar jet streak in proximity to the gravity wave generation region. This simulated restructuring of the mid-upper tropospheric jet streak is the result of a four stage process. During stage 1, the wind adjusts to the mass field as the jet streak exit region propagates into the inflection point between the upstream trough and downstream ridge in the height field. Stage 2 is initiated as the mass field is forced to adjust to the new ageostrophic wind field created during stage 1. Stage 3 is defined by a second geostrophic adjustment process occurring in a similar manner but to the south and east of the adjustment which occurs during stage 1. A low-level mesoscale jetlet is formed during stage 4 in response to the low-level pressure falls that are established during stage 3. The perturbation of this jetlet, caused by orographically-induced adiabatic and diabatic physical processes, is the likely mechanism responsible for the generation of the first and second episode of observed gravity waves. The dynamics responsible for this wave episode are discussed as differential surface sensible heating inducing an orographically-forced mountain-plains solenoid, resulting in the formation of additional mesoscale jetlets and internal gravity waves. Also discussed is how convective latent heating modifies the numerically simulated terrain-induced internal gravity waves, especially their amplitude and phase velocities, which provide better agreement with those wave characteristics observed in nature. Finally, the three

Characterization of Three-Stream Jet Flow Fields

NASA Technical Reports Server (NTRS)

Henderson, Brenda S.; Wernet, Mark P.

2016-01-01

Flow-field measurements were conducted on single-, dual- and three-stream jets using two-component and stereo Particle Image Velocimetry (PIV). The flow-field measurements complimented previous acoustic measurements. The exhaust system consisted of externally-plugged, externally-mixed, convergent nozzles. The study used bypass-to-core area ratios equal to 1.0 and 2.5 and tertiary-to-core area ratios equal to 0.6 and 1.0. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated high-subsonic conditions. Centerline velocity decay rates for the single-, dual- and three-stream axisymmetric jets compared well when axial distance was normalized by an equivalent diameter based on the nozzle system total exit area. The tertiary stream had a greater impact on the mean axial velocity for the small bypass-to-core area ratio nozzles than for large bypass-to-core area ratio nozzles. Normalized turbulence intensities were similar for the single-, dual-, and three-stream unheated jets due to the small difference (10 percent) in the core and bypass velocities for the dual-stream jets and the low tertiary velocity (50 percent of the core stream) for the three-stream jets. For heated jet conditions where the bypass velocity was 65 percent of the core velocity, additional regions of high turbulence intensity occurred near the plug tip which were not present for the unheated jets. Offsetting the tertiary stream moved the peak turbulence intensity levels upstream relative to those for all axisymmetric jets investigated.

Characterization of Three-Stream Jet Flow Fields

NASA Technical Reports Server (NTRS)

Henderson, Brenda S.; Wernet, Mark P.

2016-01-01

Flow-field measurements were conducted on single-, dual- and three-stream jets using two-component and stereo Particle Image Velocimetry (PIV). The flow-field measurements complimented previous acoustic measurements. The exhaust system consisted of externally-plugged, externally-mixed, convergent nozzles. The study used bypass-to-core area ratios equal to 1.0 and 2.5 and tertiary-to-core area ratios equal to 0.6 and 1.0. Axisymmetric and offset tertiary nozzles were investigated for heated and unheated high-subsonic conditions. Centerline velocity decay rates for the single-, dual- and three-stream axisymmetric jets compared well when axial distance was normalized by an equivalent diameter based on the nozzle system total exit area. The tertiary stream had a greater impact on the mean axial velocity for the small bypass-to-core area ratio nozzles than for large bypass-to-core area ratio nozzles. Normalized turbulence intensities were similar for the single-, dual-, and three-stream unheated jets due to the small difference (10%) in the core and bypass velocities for the dual-stream jets and the low tertiary velocity (50% of the core stream) for the three-stream jets. For heated jet conditions where the bypass velocity was 65% of the core velocity, additional regions of high turbulence intensity occurred near the plug tip which were not present for the unheated jets. Offsetting the tertiary stream moved the peak turbulence intensity levels upstream relative to those for all axisymmetric jets investigated.

Novel symmetries in Weyl-invariant gravity with massive gauge field

NASA Astrophysics Data System (ADS)

Abhinav, K.; Shukla, A.; Panigrahi, P. K.

2016-11-01

The background field method is used to linearize the Weyl-invariant scalar-tensor gravity, coupled with a Stückelberg field. For a generic background metric, this action is found not to be invariant, under both a diffeomorphism and generalized Weyl symmetry, the latter being a combination of gauge and Weyl transformations. Interestingly, the quadratic Lagrangian, emerging from a background of Minkowski metric, respects both transformations independently. The Becchi-Rouet-Stora-Tyutin symmetry of scalar-tensor gravity coupled with a Stückelberg-like massive gauge particle, possessing a diffeomorphism and generalized Weyl symmetry, reveals that in both cases negative-norm states with unphysical degrees of freedom do exist. We then show that, by combining diffeomorphism and generalized Weyl symmetries, all the ghost states decouple, thereby removing the unphysical redundancies of the theory. During this process, the scalar field does not represent any dynamic mode, yet modifies the usual harmonic gauge condition through non-minimal coupling with gravity.

Search for gauge extensions of the MSSM at the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Ahmed; Demir, Durmus A.; Department of Physics, Izmir Institute of Technology, IZTECH, TR35430 Izmir

2009-05-01

The extensions of the minimal supersymmetric model (MSSM), driving mainly from the need to solve the {mu} problem, involve novel matter species and gauge groups. These extended MSSM models can be searched for at the LHC via the effects of the gauge and Higgs bosons or their fermionic partners. Traditionally, the focus has been on the study of the extra forces induced by the new gauge and Higgs bosons present in such models. An alternative way of studying such effects is through the superpartners of matter species and the gauge forces. We thus consider a U(1)' gauge extension of themore » MSSM, and perform an extensive study of the signatures of the model through the production and decays of the scalar quarks and gluino, which are expected to be produced copiously at the LHC. After a detailed study of the distinctive features of such models with regard to the signatures at the LHC, we carry out a detailed Monte Carlo analysis of the signals from the process pp{yields}n leptons+m jets+Ee{sub T}, and compare the resulting distributions with those predicted by the MSSM. Our results show that the searches for the extra gauge interactions in the supersymmetric framework can proceed not only through the forces mediated by the gauge and Higgs bosons but also through the superpartner forces mediated by the gauge and Higgs fermions. Analysis of the events induced by the squark/gluino decays presented here is complementary to the direct Z' searches at the LHC.« less

AdS/CFT and local renormalization group with gauge fields

NASA Astrophysics Data System (ADS)

Kikuchi, Ken; Sakai, Tadakatsu

2016-03-01

We revisit a study of local renormalization group (RG) with background gauge fields incorporated using the AdS/CFT correspondence. Starting with a (d+1)-dimensional bulk gravity coupled to scalars and gauge fields, we derive a local RG equation from a flow equation by working in the Hamilton-Jacobi formulation of the bulk theory. The Gauss's law constraint associated with gauge symmetry plays an important role. RG flows of the background gauge fields are governed by vector β-functions, and some of their interesting properties are known to follow. We give a systematic rederivation of them on the basis of the flow equation. Fixing an ambiguity of local counterterms in such a manner that is natural from the viewpoint of the flow equation, we determine all the coefficients uniquely appearing in the trace of the stress tensor for d=4. A relation between a choice of schemes and a virial current is discussed. As a consistency check, these are found to satisfy the integrability conditions of local RG transformations. From these results, we are led to a proof of a holographic c-theorem by determining a full family of schemes where a trace anomaly coefficient is related with a holographic c-function.

Construction of non-Abelian gauge theories on noncommutative spaces

NASA Astrophysics Data System (ADS)

Jurčo, B.; Möller, L.; Schraml, S.; Schupp, P.; Wess, J.

We present a formalism to explicitly construct non-Abelian gauge theories on noncommutative spaces (induced via a star product with a constant Poisson tensor) from a consistency relation. This results in an expansion of the gauge parameter, the noncommutative gauge potential and fields in the fundamental representation, in powers of a parameter of the noncommutativity. This allows the explicit construction of actions for these gauge theories.

RELATIVISTIC MHD SIMULATIONS OF COLLISION-INDUCED MAGNETIC DISSIPATION IN POYNTING-FLUX-DOMINATED JETS/OUTFLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Wei; Zhang, Bing; Li, Hui

We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.« less

Impact of electric field from a plasma jet on biological targets

NASA Astrophysics Data System (ADS)

Douat, Claire; Darny, Thibault; Iseni, Sylvain; Damany, Xavier; Dozias, Sebastien; Pouvesle, Jean-Michel; Robert, Eric; Vijayarangan, Vinodini; Delalande, Anthony; Pichon, Chantal

2016-09-01

Atmospheric pressure plasma jets have demonstrated their ability in biomedical applications thanks to their low gas temperature and their capacity to produce radicals, ions, electrons, UV radiation and electric fields. However the understanding of the interactions between the plasma and living cells and tissues is still far from being completely understood. Recently, Robert et al characterized two components of the electric field from a plasma jet and showed that the latter can propagate deeply in tissues on several mm. In this work, we focus on the study of the electric field induced by the plasma and its influence on the cell membrane. Propidium iodide, dextran sulfate and plasmid DNA are used to measure the permeability of the membrane, while an electro-optic probe is used to measure the longitudinal and the radial components of the electric field. The two components are both spatially and temporally resolved. To investigate the contribution of the electric field on the cell membrane, a dielectric barrier is used between the plasma and the biological target. A comparison with and without the barrier will be presented for both biological and agriculture applications.

Advances in synthetic gauge fields for light through dynamic modulation

NASA Astrophysics Data System (ADS)

Hey, Daniel; Li, Enbang

2018-04-01

Photons are weak particles that do not directly couple to magnetic fields. However, it is possible to generate a photonic gauge field by breaking reciprocity such that the phase of light depends on its direction of propagation. This non-reciprocal phase indicates the presence of an effective magnetic field for the light itself. By suitable tailoring of this phase, it is possible to demonstrate quantum effects typically associated with electrons, and, as has been recently shown, non-trivial topological properties of light. This paper reviews dynamic modulation as a process for breaking the time-reversal symmetry of light and generating a synthetic gauge field, and discusses its role in topological photonics, as well as recent developments in exploring topological photonics in higher dimensions.

Advances in synthetic gauge fields for light through dynamic modulation.

PubMed

Hey, Daniel; Li, Enbang

2018-04-01

Photons are weak particles that do not directly couple to magnetic fields. However, it is possible to generate a photonic gauge field by breaking reciprocity such that the phase of light depends on its direction of propagation. This non-reciprocal phase indicates the presence of an effective magnetic field for the light itself. By suitable tailoring of this phase, it is possible to demonstrate quantum effects typically associated with electrons, and, as has been recently shown, non-trivial topological properties of light. This paper reviews dynamic modulation as a process for breaking the time-reversal symmetry of light and generating a synthetic gauge field, and discusses its role in topological photonics, as well as recent developments in exploring topological photonics in higher dimensions.

Advances in synthetic gauge fields for light through dynamic modulation

PubMed Central

Li, Enbang

2018-01-01

Photons are weak particles that do not directly couple to magnetic fields. However, it is possible to generate a photonic gauge field by breaking reciprocity such that the phase of light depends on its direction of propagation. This non-reciprocal phase indicates the presence of an effective magnetic field for the light itself. By suitable tailoring of this phase, it is possible to demonstrate quantum effects typically associated with electrons, and, as has been recently shown, non-trivial topological properties of light. This paper reviews dynamic modulation as a process for breaking the time-reversal symmetry of light and generating a synthetic gauge field, and discusses its role in topological photonics, as well as recent developments in exploring topological photonics in higher dimensions. PMID:29765688

One-dimensional nonlinear instability study of a slightly viscoelastic, perfectly conducting liquid jet under a radial electric field

NASA Astrophysics Data System (ADS)

Li, Fang; Yin, Xie-Yuan; Yin, Xie-Zhen

2016-05-01

A one-dimensional electrified viscoelastic model is built to study the nonlinear behavior of a slightly viscoelastic, perfectly conducting liquid jet under a radial electric field. The equations are solved numerically using an implicit finite difference scheme together with a boundary element method. The electrified viscoelastic jet is found to evolve into a beads-on-string structure in the presence of the radial electric field. Although the radial electric field greatly enhances the linear instability of the jet, its influence on the decay of the filament thickness is limited during the nonlinear evolution of the jet. On the other hand, the radial electric field induces axial non-uniformity of the first normal stress difference within the filament. The first normal stress difference in the center region of the filament may be greatly decreased by the radial electric field. The regions with/without satellite droplets are illuminated on the χ (the electrical Bond number)-k (the dimensionless wave number) plane. Satellite droplets may be formed for larger wave numbers at larger radial electric fields.

Prediction techniques for jet-induced effects in hover on STOVL aircraft

NASA Technical Reports Server (NTRS)

Wardwell, Douglas A.; Kuhn, Richard E.

1991-01-01

Prediction techniques for jet induced lift effects during hover are available, relatively easy to use, and produce adequate results for preliminary design work. Although deficiencies of the current method were found, it is still currently the best way to estimate jet induced lift effects short of using computational fluid dynamics. Its use is summarized. The new summarized method, represents the first step toward the use of surface pressure data in an empirical method, as opposed to just balance data in the current method, for calculating jet induced effects. Although the new method is currently limited to flat plate configurations having two circular jets of equal thrust, it has the potential of more accurately predicting jet induced effects including a means for estimating the pitching moment in hover. As this method was developed from a very limited amount of data, broader applications of the method require the inclusion of new data on additional configurations. However, within this small data base, the new method does a better job in predicting jet induced effects in hover than the current method.

Identifying a new particle with jet substructures

DOE PAGES

Han, Chengcheng; Kim, Doojin; Kim, Minho; ...

2017-01-09

Here, we investigate a potential of determining properties of a new heavy resonance of mass O(1)TeV which decays to collimated jets via heavy Standard Model intermediary states, exploiting jet substructure techniques. Employing the Z gauge boson as a concrete example for the intermediary state, we utilize a "merged jet" defined by a large jet size to capture the two quarks from its decay. The use of the merged jet bene ts the identification of a Z-induced jet as a single, reconstructed object without any combinatorial ambiguity. We also find that jet substructure procedures may enhance features in some kinematic observablesmore » formed with subjet four-momenta extracted from a merged jet. This observation motivates us to feed subjet momenta into the matrix elements associated with plausible hypotheses on the nature of the heavy resonance, which are further processed to construct a matrix element method (MEM)-based observable. For both moderately and highly boosted Z bosons, we demonstrate that the MEM in combination with jet substructure techniques can be a very powerful tool for identifying its physical properties. Finally, we discuss effects from choosing different jet sizes for merged jets and jet-grooming parameters upon the MEM analyses.« less

Evaluating the catching performance of aerodynamic rain gauges through field comparisons and CFD modelling

NASA Astrophysics Data System (ADS)

Pollock, Michael; Colli, Matteo; Stagnaro, Mattia; Lanza, Luca; Quinn, Paul; Dutton, Mark; O'Donnell, Greg; Wilkinson, Mark; Black, Andrew; O'Connell, Enda

2016-04-01

Accurate rainfall measurement is a fundamental requirement in a broad range of applications including flood risk and water resource management. The most widely used method of measuring rainfall is the rain gauge, which is often also considered to be the most accurate. In the context of hydrological modelling, measurements from rain gauges are interpolated to produce an areal representation, which forms an important input to drive hydrological models and calibrate rainfall radars. In each stage of this process another layer of uncertainty is introduced. The initial measurement errors are propagated through the chain, compounding the overall uncertainty. This study looks at the fundamental source of error, in the rainfall measurement itself; and specifically addresses the largest of these, the systematic 'wind-induced' error. Snowfall is outside the scope. The shape of a precipitation gauge significantly affects its collection efficiency (CE), with respect to a reference measurement. This is due to the airflow around the gauge, which causes a deflection in the trajectories of the raindrops near the gauge orifice. Computational Fluid-Dynamic (CFD) simulations are used to evaluate the time-averaged airflows realized around the EML ARG100, EML SBS500 and EML Kalyx-RG rain gauges, when impacted by wind. These gauges have a similar aerodynamic profile - a shape comparable to that of a champagne flute - and they are used globally. The funnel diameter of each gauge, respectively, is 252mm, 254mm and 127mm. The SBS500 is used by the UK Met Office and the Scottish Environmental Protection Agency. Terms of comparison are provided by the results obtained for standard rain gauge shapes manufactured by Casella and OTT which, respectively, have a uniform and a tapered cylindrical shape. The simulations were executed for five different wind speeds; 2, 5, 7, 10 and 18 ms-1. Results indicate that aerodynamic gauges have a different impact on the time-averaged airflow patterns

Dirichlet to Neumann operator for Abelian Yang-Mills gauge fields

NASA Astrophysics Data System (ADS)

Díaz-Marín, Homero G.

We consider the Dirichlet to Neumann operator for Abelian Yang-Mills boundary conditions. The aim is constructing a complex structure for the symplectic space of boundary conditions of Euler-Lagrange solutions modulo gauge for space-time manifolds with smooth boundary. Thus we prepare a suitable scenario for geometric quantization within the reduced symplectic space of boundary conditions of Abelian gauge fields.

Measuring medium-induced gluons via jet grooming

NASA Astrophysics Data System (ADS)

Tywoniuk, Konrad; Mehtar-Tani, Yacine

2017-11-01

Jet substructure observables and applications of jet grooming techniques in heavy-ion collisions are still in its infancy and provide new alleys for studying medium modifications of perturbative degrees of freedom. We note that these measurements, given the right transverse momentum range, can be uniquely sensitive to rare medium-induced emissions inside of the jet cone. This corresponds to an infrared enhancement that would, for instance, affect the distribution of the groomed momentum-sharing variable zg measured using the SoftDrop procedure.

N=2 gauge theories and degenerate fields of Toda theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanno, Shoichi; Matsuo, Yutaka; Shiba, Shotaro

We discuss the correspondence between degenerate fields of the W{sub N} algebra and punctures of Gaiotto's description of the Seiberg-Witten curve of N=2 superconformal gauge theories. Namely, we find that the type of degenerate fields of the W{sub N} algebra, with null states at level one, is classified by Young diagrams with N boxes, and that the singular behavior of the Seiberg-Witten curve near the puncture agrees with that of W{sub N} generators. We also find how to translate mass parameters of the gauge theory to the momenta of the Toda theory.

Magnetic Fields Sculpt Narrow Jets From Dying Star

NASA Astrophysics Data System (ADS)

2006-03-01

Molecules spewed outward from a dying star are confined into narrow jets by a tightly-wound magnetic field, according to astronomers who used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope to study an old star about 8,500 light-years from Earth. Magnetic Field Around Jet Artist's Conception Shows Tightly-Wound Magnetic Field Confining Jet CREDIT: NRAO/AUI/NSF (Click on image for larger version) The star, called W43A, in the constellation Aquila, is in the process of forming a planetary nebula, a shell of brightly-glowing gas lit by the hot ember into which the star will collapse. In 2002, astronomers discovered that the aging star was ejecting twin jets of water molecules. That discovery was a breakthrough in understanding how many planetary nebulae are formed into elongated shapes. "The next question was, what is keeping this outpouring of material confined into narrow jets? Theoreticians suspected magnetic fields, and we now have found the first direct evidence that a magnetic field is confining such a jet," said Wouter Vlemmings, a Marie Curie Fellow working at the Jodrell Bank Observatory of the University of Manchester in England. "Magnetic fields previously have been detected in jets emitted by quasars and protostars, but the evidence was not conclusive that the magnetic fields were actually confining the jets. These new VLBA observations now make that direct connection for the very first time," Vlemmings added. By using the VLBA to study the alignment, or polarization, of radio waves emitted by water molecules in the jets, the scientists were able to determine the strength and orientation of the magnetic field surrounding the jets. "Our observations support recent theoretical models in which magnetically-confined jets produce the sometimes-complex shapes we see in planetary nebulae," said Philip Diamond, also of Jodrell Bank Observatory. During their "normal" lives, stars similar to our Sun are powered by the nuclear fusion

Electric-field driven jetting from dielectric liquids

NASA Astrophysics Data System (ADS)

Jayasinghe, S. N.; Edirisinghe, M. J.

2004-11-01

Three dielectric (electrical conductivity ˜10-13Sm-1) Newtonian liquids with viscosity in the range 1-100 mPa s were passed through a needle at a controlled flow rate under the influence of an electric field. At an electric field strength of 1.5kV/mm, the liquid exiting the needle instantaneously transformed from dripping droplets to an elliptically pendent droplet from the apex of which a fine jet evolved. Thus, a jet can be obtained on demand, and in this letter we define this phenomenon and explain a basis for it.

Abundant stable gauge field hair for black holes in anti-de Sitter space.

PubMed

Baxter, J E; Helbling, Marc; Winstanley, Elizabeth

2008-01-11

We present new hairy black hole solutions of SU(N) Einstein-Yang-Mills (EYM) theory in asymptotically anti-de Sitter (AdS) space. These black holes are described by N+1 independent parameters and have N-1 independent gauge field degrees of freedom. Solutions in which all gauge field functions have no zeros exist for all N, and for a sufficiently large (and negative) cosmological constant. At least some of these solutions are shown to be stable under classical, linear, spherically symmetric perturbations. Therefore there is no upper bound on the amount of stable gauge field hair with which a black hole in AdS can be endowed.

Effect of DC magnetic field on atmospheric pressure argon plasma jet

NASA Astrophysics Data System (ADS)

Safari, R.; Sohbatzadeh, F.

2015-05-01

In this work, external DC magnetic field effect on the atmospheric pressure plasma jet has been investigated, experimentally. The magnetic field has been produced using a Helmholtz coil configuration. It has been applied parallel and transverse to the jet flow. The strength of the DC magnetic field is 0-0.28 and 0-0.57 Tesla between the two coils in parallel and transverse applications, respectively. It has been shown that the plasma gas flow plays the main role in magneto-active collision-dominated plasma. The effect of plasma fluid velocity on the jet emission has been discussed, qualitatively. It has been observed that the external DC magnetic field has different trends in parallel and transverse applications. The measurements reveal that the plasma jet irradiance increases in parallel field, while it decreases in transverse field. The former has been attributed to increasing plasma number density and the latter to loss of plasma species that reduces the magneto-plasma jet irradiance and in turn shrinks plasma jet number density. As a result, the plasma fluid velocity is responsible for such trends though the magneto-active plasma remains isotropic.

Anisotopic inflation with a non-abelian gauge field in Gauss-Bonnet gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lahiri, Sayantani, E-mail: sayantani.lahiri@gmail.com

2017-01-01

In presence of Gauss-Bonnet corrections, we study anisotropic inflation aided by a massless SU(2) gauge field where both the gauge field and the Gauss-Bonnet term are non-minimally coupled to the inflaton. In this scenario, under slow-roll approximations, the anisotropic inflation is realized as an attractor solution with quadratic forms of inflaton potential and Gauss-Bonnet coupling function. We show that the degree of anisotropy is proportional to the additive combination of two slow-roll parameters of the theory. The anisotropy may become either positive or negative similar to the non-Gauss-Bonnet framework, a feature of the model for anisotropic inflation supported by amore » non-abelian gauge field but the effect of Gauss-Bonnet term further enhances or suppresses the generated anisotropy.« less

Higgsed Gauge-flation

NASA Astrophysics Data System (ADS)

Adshead, Peter; Sfakianakis, Evangelos I.

2017-08-01

We study a variant of Gauge-flation where the gauge symmetry is spontaneously broken by a Higgs sector. We work in the Stueckelberg limit and demonstrate that the dynamics remain (catastrophically) unstable for cases where the gauge field masses satisfy γ < 2, where γ = g 2 ψ 2/ H 2, g is the gauge coupling, ψ is the gauge field vacuum expectation value, and H is the Hubble rate. We compute the spectrum of density fluctuations and gravitational waves, and show that the model can produce observationally viable spectra. The background gauge field texture violates parity, resulting in a chiral gravitational wave spectrum. This arises due to an exponential enhancement of one polarization of the spin-2 fluctuation of the gauge field. Higgsed Gauge-flation can produce observable gravitational waves at inflationary energy scales well below the GUT scale.

Bipolar Jets Launched by a Mean-field Accretion Disk Dynamo

NASA Astrophysics Data System (ADS)

Fendt, Christian; Gaßmann, Dennis

2018-03-01

By applying magnetohydrodynamic simulations, we investigate the launching of jets driven by a disk magnetic field generated by a mean-field disk dynamo. Extending our earlier studies, we explore the bipolar evolution of the disk α 2Ω-dynamo and the outflow. We confirm that a negative dynamo-α leads to a dipolar field geometry, whereas positive values generate quadrupolar fields. The latter remain mainly confined to the disk and cannot launch outflows. We investigate a parameter range for the dynamo-α ranging from a critical value below which field generation is negligible, {α }0,{crit}=-0.0005, to α 0 = ‑1.0. For weak | {α }0| ≤slant 0.07, two magnetic loop structures with opposite polarity may arise, which leads to reconnection and disturbs the field evolution and accretion-ejection process. For a strong dynamo-α, a higher poloidal magnetic energy is reached, roughly scaling with {E}mag}∼ | {α }0| , which also leads to higher accretion and ejection rates. The terminal jet speed is governed by the available magnetic energy and increases with the dynamo-α. We find jet velocities on the order of the inner disk Keplerian velocity. For a strong dynamo-α, oscillating dynamo modes may occur that can lead to a pulsed ejection. This is triggered by an oscillating mode in the toroidal field component. The oscillation period is comparable to the Keplerian timescale in the launching region, thus too short to be associated with the knots in observed jets. We find a hemispherically asymmetric evolution for the jet and counter-jet in the mass flux and field structure.

Numerical analysis of exhaust jet secondary combustion in hypersonic flow field

NASA Astrophysics Data System (ADS)

Yang, Tian-Peng; Wang, Jiang-Feng; Zhao, Fa-Ming; Fan, Xiao-Feng; Wang, Yu-Han

2018-05-01

The interaction effect between jet and control surface in supersonic and hypersonic flow is one of the key problems for advanced flight control system. The flow properties of exhaust jet secondary combustion in a hypersonic compression ramp flow field were studied numerically by solving the Navier-Stokes equations with multi-species and combustion reaction effects. The analysis was focused on the flow field structure and the force amplification factor under different jet conditions. Numerical results show that a series of different secondary combustion makes the flow field structure change regularly, and the temperature increases rapidly near the jet exit.

Effect of external electric and magnetic field on propagation of atmospheric pressure plasma jet

NASA Astrophysics Data System (ADS)

Zhu, Ping; Meng, Zhaozhong; Hu, Haixin; Ouyang, Jiting

2017-10-01

The behaviors of atmospheric pressure plasma jet produced by a coplanar dielectric barrier discharge (CDBD) in helium in external electrostatic and magnetic field are investigated experimentally. Time-resolved ICCD images of jet in electric field, magnetic field, and floating metal ring are recorded, respectively. The results show that the jet dynamics is affected significantly by a metal ring, an electric, and/or a magnetic field. In a transverse electric field, the jet shows behavior of deflection, broadening, and shortening according to the structure of electric field. In a transverse magnetic field, the jet deflects to up or down depending on the magnetic direction. The jet can be slowed down or obstructed by a floating metal ring on the jet path, but will still pass through the tube at higher applied voltages of DBD, without significant change in jet length or shape out of the tube compared with that without metal ring. A positive DC voltage on the metal ring helps to improve the jet length, but a negative voltage will reduce the length or completely stop the jet. The electric field to sustain the jet in helium is estimated to be about 24 ± 15 kV/cm from this experiment.

Higgsed Gauge-flation

DOE PAGES

Adshead, Peter; Sfakianakis, Evangelos I.

2017-08-29

We study a variant of Gauge-flation where the gauge symmetry is spontaneously broken by a Higgs sector. Here, we work in the Stueckelberg limit and demonstrate that the dynamics remain (catastrophically) unstable for cases where the gauge field masses satisfy γ< 2, where γ= g 2 2=ψH 2, g is the gauge coupling, ψ is the gauge field vacuum expectation value, and H is the Hubble rate. We compute the spectrum of density uctuations and gravitational waves, and show that the model can produce observationally viable spectra. The background gauge field texture violates parity, resulting in a chiral gravitational wavemore » spectrum. This arises due to an exponential enhancement of one polarization of the spin-2 fluctuation of the gauge field. Higgsed Gauge-flation can produce observable gravitational waves at in inflationary energy scales well below the GUT scale.« less

Higgsed Gauge-flation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adshead, Peter; Sfakianakis, Evangelos I.

We study a variant of Gauge-flation where the gauge symmetry is spontaneously broken by a Higgs sector. Here, we work in the Stueckelberg limit and demonstrate that the dynamics remain (catastrophically) unstable for cases where the gauge field masses satisfy γ< 2, where γ= g 2 2=ψH 2, g is the gauge coupling, ψ is the gauge field vacuum expectation value, and H is the Hubble rate. We compute the spectrum of density uctuations and gravitational waves, and show that the model can produce observationally viable spectra. The background gauge field texture violates parity, resulting in a chiral gravitational wavemore » spectrum. This arises due to an exponential enhancement of one polarization of the spin-2 fluctuation of the gauge field. Higgsed Gauge-flation can produce observable gravitational waves at in inflationary energy scales well below the GUT scale.« less

The Characterization of Military Aircraft Jet Noise Using Near-Field Acoustical Holography Methods

NASA Astrophysics Data System (ADS)

Wall, Alan Thomas

The noise emissions of jets from full-scale engines installed on military aircraft pose a significant hearing loss risk to military personnel. Noise reduction technologies and the development of operational procedures that minimize noise exposure to personnel are enhanced by the accurate characterization of noise sources within a jet. Hence, more than six decades of research have gone into jet noise measurement and prediction. In the past decade, the noise-source visualization tool near-field acoustical holography (NAH) has been applied to jets. NAH fits a weighted set of expansion wave functions, typically planar, cylindrical, or spherical, to measured sound pressures in the field. NAH measurements were made of a jet from an installed engine on a military aircraft. In the present study, the algorithm of statistically optimized NAH (SONAH) is modified to account for the presence of acoustic reflections from the concrete surface over which the jet was measured. The three dimensional field in the jet vicinity is reconstructed, and information about sources is inferred from reconstructions at the boundary of the turbulent jet flow. Then, a partial field decomposition (PFD) is performed, which represents the total field as the superposition of multiple, independent partial fields. This is the most direct attempt to equate partial fields with independent sources in a jet to date.

Pure gauge spin-orbit couplings

NASA Astrophysics Data System (ADS)

Shikakhwa, M. S.

2017-01-01

Planar systems with a general linear spin-orbit interaction (SOI) that can be cast in the form of a non-Abelian pure gauge field are investigated using the language of non-Abelian gauge field theory. A special class of these fields that, though a 2×2 matrix, are Abelian are seen to emerge and their general form is given. It is shown that the unitary transformation that gauges away these fields induces at the same time a rotation on the wave function about a fixed axis but with a space-dependent angle, both of which being characteristics of the SOI involved. The experimentally important case of equal-strength Rashba and Dresselhaus SOI (R+D SOI) is shown to fall within this special class of Abelian gauge fields, and the phenomenon of persistent spin helix (PSH) that emerges in the presence of this latter SOI in a plane is shown to fit naturally within the general formalism developed. The general formalism is also extended to the case of a particle confined to a ring. It is shown that the Hamiltonian on a ring in the presence of equal-strength R+D SOI is unitarily equivalent to that of a particle subject to only a spin-independent but θ-dependent potential with the unitary transformation relating the two being again the space-dependent rotation operator characteristic of R+D SOI.

Jet-induced ground effects on a parametric flat-plate model in hover

NASA Technical Reports Server (NTRS)

Wardwell, Douglas A.; Hange, Craig E.; Kuhn, Richard E.; Stewart, Vearl R.

1993-01-01

The jet-induced forces generated on short takeoff and vertical landing (STOVL) aircraft when in close proximity to the ground can have a significant effect on aircraft performance. Therefore, accurate predictions of these aerodynamic characteristics are highly desirable. Empirical procedures for estimating jet-induced forces during the vertical/short takeoff and landing (V/STOL) portions of the flight envelope are currently limited in accuracy. The jet-induced force data presented significantly add to the current STOVL configurations data base. Further development of empirical prediction methods for jet-induced forces, to provide more configuration diversity and improved overall accuracy, depends on the viability of this STOVL data base. The data base may also be used to validate computational fluid dynamics (CFD) analysis codes. The hover data obtained at the NASA Ames Jet Calibration and Hover Test (JCAHT) facility for a parametric flat-plate model is presented. The model tested was designed to allow variations in the planform aspect ratio, number of jets, nozzle shape, and jet location. There were 31 different planform/nozzle configurations tested. Each configuration had numerous pressure taps installed to measure the pressures on the undersurface of the model. All pressure data along with the balance jet-induced lift and pitching-moment increments are tabulated. For selected runs, pressure data are presented in the form of contour plots that show lines of constant pressure coefficient on the model undersurface. Nozzle-thrust calibrations and jet flow-pressure survey information are also provided.

Relativistic jets without large-scale magnetic fields

NASA Astrophysics Data System (ADS)

Parfrey, K.; Giannios, D.; Beloborodov, A.

2014-07-01

The canonical model of relativistic jets from black holes requires a large-scale ordered magnetic field to provide a significant magnetic flux through the ergosphere--in the Blandford-Znajek process, the jet power scales with the square of the magnetic flux. In many jet systems the presence of the required flux in the environment of the central engine is questionable. I will describe an alternative scenario, in which jets are produced by the continuous sequential accretion of small magnetic loops. The magnetic energy stored in these coronal flux systems is amplified by the differential rotation of the accretion disc and by the rotating spacetime of the black hole, leading to runaway field line inflation, magnetic reconnection in thin current layers, and the ejection of discrete bubbles of Poynting-flux-dominated plasma. For illustration I will show the results of general-relativistic force-free electrodynamic simulations of rotating black hole coronae, performed using a new resistivity model. The dissipation of magnetic energy by coronal reconnection events, as demonstrated in these simulations, is a potential source of the observed high-energy emission from accreting compact objects.

An Investigation of Transonic Flow Fields Surrounding Hot and Cold Sonic Jets

NASA Technical Reports Server (NTRS)

Lee, George

1961-01-01

An investigation at free-stream Mach numbers of 0.90 t o 1.10 was made to determine (1) the jet boundaries and the flow fields around hot and cold jets, and (2) whether a cold-gas jet could adequately simulate the boundary and flow field of hot-gas jet. Schlieren photographs and static-pressure surveys were taken in the vacinity of a sonic jet which was operated over a range of jet pressure ratios of 1 to 6, specific heat ratios at the nozzle exit of 1.29 and 1.40, and jet temperatures up to 2600 R.

Magnetic Fields in Blazar Jets: Jet-Alignment of Radio and Optical Polarization over 20-30 Years

NASA Astrophysics Data System (ADS)

Wills, Beverley J.; Aller, M. F.; Caldwell, C.; Aller, H. D.

2012-01-01

Blazars are highly active nuclei of distant galaxies. They produce synchrotron-emitting relativistic jets on scales of less than a parsec to many Kpc. When viewed head-on, as opposed to in the plane of the sky, the jet motion appears superluminal, and the emission is Doppler boosted. Blazars show rapid radio and optical variability in flux density and polarization. There are two types of blazars that can have strong synchrotron continua: some quasars with strong broad emission lines, and BL Lac objects with weak or undetected broad lines. We have compiled optical linear polarization measurements of more than 100 blazars, including archival data from McDonald Observatory. While the optical data are somewhat sparsely sampled, The University of Michigan Radio Astronomical Observatory observed many blazars over 20-30 years, often well-sampled over days to weeks, enabling quasi-simultaneous comparison of optical and radio polarization position angles (EVPAs). We also collected data on jet direction -- position angles of the jet component nearest the radio core. The project is unique in examining the polarization and jet behavior over many years. BL Lac objects tend to have stable optically thin EVPA in the jet direction, meaning magnetic field is perpendicular to jet flow, often interpreted as the magnetic field compressed by shocks. In quasar-blazars optical and radio EVPA often changes between parallel or perpendicular to the jet direction, even in the same object. The underlying B field of the jet is is parallel to the flow, with approximately 90 degree changes resulting from shocks. For both BL Lac objects & quasars, the scatter in EVPA usually increases from low frequencies (4.8 GHz) through 14.5 GHz through optical. The wide optical-radio frequency range allows us to investigate optical depth effects and the spatial origin of radio and optical emission.

Analysis of a gauged model with a spin-1/2 field directly coupled to a Rarita-Schwinger spin-3/2 field

NASA Astrophysics Data System (ADS)

Adler, Stephen L.

2018-02-01

We give a detailed analysis of an Abelianized gauge field model in which a Rarita-Schwinger spin-3/2 field is directly coupled to a spin-1/2 field. The model permits a perturbative expansion in powers of the gauge field coupling, and from the Feynman rules for the model we calculate the chiral anomaly.

Gauge symmetries of the free bosonic string field theory

NASA Astrophysics Data System (ADS)

Neveu, A.; Schwarz, J.; West, P. C.

1985-12-01

The gauge covariant local formulations of free bosonic string theories that contained a finite number of supplementary fields are extended to include an infinite number of supplementary fields. These new formulations allow the generators of the Virasoro algebra to appear on a more equal footing. Permanent address: King's College, Physics Department, London WC2R 2LS, UK.

Core shifts, magnetic fields and magnetization of extragalactic jets

NASA Astrophysics Data System (ADS)

Zdziarski, Andrzej A.; Sikora, Marek; Pjanka, Patryk; Tchekhovskoy, Alexander

2015-07-01

We study the effect of radio-jet core shift, which is a dependence of the position of the jet radio core on the observational frequency. We derive a new method of measuring the jet magnetic field based on both the value of the shift and the observed radio flux, which complements the standard method that assumes equipartition. Using both methods, we re-analyse the blazar sample of Zamaninasab et al. We find that equipartition is satisfied only if the jet opening angle in the radio core region is close to the values found observationally, ≃0.1-0.2 divided by the bulk Lorentz factor, Γj. Larger values, e.g. 1/Γj, would imply magnetic fields much above equipartition. A small jet opening angle implies in turn the magnetization parameter of ≪1. We determine the jet magnetic flux taking into account this effect. We find that the transverse-averaged jet magnetic flux is fully compatible with the model of jet formation due to black hole (BH) spin-energy extraction and the accretion being a magnetically arrested disc (MAD). We calculate the jet average mass-flow rate corresponding to this model and find it consists of a substantial fraction of the mass accretion rate. This suggests the jet composition with a large fraction of baryons. We also calculate the average jet power, and find it moderately exceeds the accretion power, dot{M} c^2, reflecting BH spin energy extraction. We find our results for radio galaxies at low Eddington ratios are compatible with MADs but require a low radiative efficiency, as predicted by standard accretion models.

Particle acceleration, magnetic field generation, and emission in relativistic pair jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Kouveliotou, C.; Fishman, G. J.; Mizuno, Y.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Recent simulations show that the Weibel instability created by relativistic pair jets is responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. The Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. This instability is also responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The jitter radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Planar laser-induced fluorescence measurements of high-enthalpy free jet flow with nitric oxide

NASA Technical Reports Server (NTRS)

Palmer, Jennifer L.; Mcmillin, Brian K.; Hanson, Ronald K.

1992-01-01

Planar laser-induced fluorescence (PLIF) measurements of property fields in a high-enthalpy, supersonic, underexpanded free jet generated in a reflection-type shock tunnel are reported. PLIF images showing velocity and temperature sensitivity are presented. The inferred radial velocity and relative rotational temperature fields are found to be in agreement with those predicted by a numerical simulation of the flowfield using the method of characteristics.

Modelling of the solar/stellar wind two-jet structure induced by azimuthal stellar magnetic field

NASA Astrophysics Data System (ADS)

Golikov, Evgeniy; Belov, Nickolai; Alexashov, Dmitry; Izmodenov, Vladislav

2016-07-01

Opher et al. (2015), Drake et al. (2015) have shown that the heliospheric magnetic field results in formation of two-jet structure of the solar wind flow in the inner heliosheath, i.e. in the subsonic region between the heliospheric termination shock and the heliopause. In this scenario the heliopause has tube-like topology as compared with sheet-like topology in the most models of the global heliosphere (e.g. Izmodenov and Alexashov, 2015). In this paper we explore the two-jet scenario for the simplified astrosphere with the star is at rest with respect to the circumstellar medium and radial magnetic field is neglected as compared with azimuthal component. Our work is further elaboration of Drake et al. (2015) paper. We performed parametric numerical analyses showing how the structure of the flow changes depending on the model parameters. Also, we present three first integrals of the ideal MHD equations for the considered problem and use them to get links between analytical and numerical considerations.

Jet-induced medium excitation in γ-hadron correlation at RHIC

DOE PAGES

Chen, Wei; Cao, Shanshan; Luo, Tan; ...

2017-09-25

Both jet transport and jet-induced medium excitation are investigated simultaneously within the coupled Linear Boltzmann Transport and hydro (CoLBT-hydro) model. In this coupled approach, energy-momentum deposition from propagating jet shower partons in the elastic and radiation processes is taken as a source term in hydrodynamics and the hydro background for LBT simulation is updated for next time step. We use CoLBT-hydro model to simulate γ-jet events of Au+Au collisions at RHIC. Hadron spectra from both the hadronization of jet shower partons and jet-induced medium excitation are calculated and compared to experimental data. Parton energy loss of jet shower partons leadsmore » to the suppression of hadron yields at large z T = p h T/p γ T while medium excitations leads to enhancement of hadron yields at small z T. Meanwhile, a significant broadening of low p T hadron yields and the depletion of soft hadrons in the γ direction are observed in the calculation of γ-hadron angular correlation.« less

Jet-induced medium excitation in γ-hadron correlation at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei; Cao, Shanshan; Luo, Tan

Both jet transport and jet-induced medium excitation are investigated simultaneously within the coupled Linear Boltzmann Transport and hydro (CoLBT-hydro) model. In this coupled approach, energy-momentum deposition from propagating jet shower partons in the elastic and radiation processes is taken as a source term in hydrodynamics and the hydro background for LBT simulation is updated for next time step. We use CoLBT-hydro model to simulate γ-jet events of Au+Au collisions at RHIC. Hadron spectra from both the hadronization of jet shower partons and jet-induced medium excitation are calculated and compared to experimental data. Parton energy loss of jet shower partons leadsmore » to the suppression of hadron yields at large z T = p h T/p γ T while medium excitations leads to enhancement of hadron yields at small z T. Meanwhile, a significant broadening of low p T hadron yields and the depletion of soft hadrons in the γ direction are observed in the calculation of γ-hadron angular correlation.« less

STOL landing thrust: Reverser jet flowfields

NASA Technical Reports Server (NTRS)

Kotansky, D. R.; Glaze, L. W.

1987-01-01

Analysis tools and modeling concepts for jet flow fields encountered upon use of thrust reversers for high performance military aircraft are described. A semi-empirical model of the reverser ground wall jet interaction with the uniform cross flow due to aircraft forward velocity is described. This ground interaction model is used to demonstrate exhaust gas ingestion conditions. The effects of control of exhaust jet vector angle, lateral splay, and moving versus fixed ground simulation are discussed. The Adler/Baron jet-in-cross flow model is used in conjunction with three dimensional panel methods to investigate the upper surface jet induced flow field.

Comment on "Chiral gauge field and axial anomaly in a Weyl semimetal"

NASA Astrophysics Data System (ADS)

Zhang, Kai; Zhang, Erhu; Zhang, Shengli

2017-12-01

In Liu et al. [Phys. Rev. B 87, 235306 (2013), 10.1103/PhysRevB.87.235306], the authors obtain that the cross coupling between vector gauge field and chiral gauge field can lead to the anomaly of vector current. We demonstrate that this anomaly is not a physical effect. On one hand, it can be regulated out by the proper regulation. On the other hand, it leads to unjustifiable results, the breaking of the vector gauge symmetry and the ambiguous boundary current. Moreover, the effects associated with anomaly of vector current are understood by random phase approximation (RPA) in the paper we comment on. We point out that the RPA cannot describe the effects resulting from the quantum anomaly.

Single-Shot, Volumetrically Illuminated, Three-Dimensional, Tomographic Laser-Induced-Fluorescence Imaging in a Gaseous Free Jet

DTIC Science & Technology

2016-04-28

Single- shot , volumetrically illuminated, three- dimensional, tomographic laser-induced- fluorescence imaging in a gaseous free jet Benjamin R. Halls...us.af.mil Abstract: Single- shot , tomographic imaging of the three-dimensional concentration field is demonstrated in a turbulent gaseous free jet in co-flow...2001). 6. K. M. Tacina and W. J. A. Dahm, “Effects of heat release on turbulent shear flows, Part 1. A general equivalence principle for non-buoyant

On the estimation of jet-induced fountain lift and additional suckdown in hover for two-jet configurations

NASA Technical Reports Server (NTRS)

Kuhn, Richard E.; Bellavia, David C.; Corsiglia, Victor R.; Wardwell, Douglas A.

1991-01-01

Currently available methods for estimating the net suckdown induced on jet V/STOL aircraft hovering in ground effect are based on a correlation of available force data and are, therefore, limited to configurations similar to those in the data base. Experience with some of these configurations has shown that both the fountain lift and additional suckdown are overestimated but these effects cancel each other for configurations within the data base. For other configurations, these effects may not cancel and the net suckdown could be grossly overestimated or underestimated. Also, present methods do not include the prediction of the pitching moments associated with the suckdown induced in ground effect. An attempt to develop a more logically based method for estimating the fountain lift and suckdown based on the jet-induced pressures is initiated. The analysis is based primarily on the data from a related family of three two-jet configurations (all using the same jet spacing) and limited data from two other two-jet configurations. The current status of the method, which includes expressions for estimating the maximum pressure induced in the fountain regions, and the sizes of the fountain and suckdown regions is presented. Correlating factors are developed to be used with these areas and pressures to estimate the fountain lift, the suckdown, and the related pitching moment increments.

Cold atmospheric plasma jet in an axial DC electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Li, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu; Keidar, Michael, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu

2016-08-15

Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that amore » lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.« less

Gauge field back reaction on a black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hochberg, D.; Kephart, T.W.

1993-02-15

The order-[h bar] fluctuations of gauge fields in the vicinity of a black hole can create a repulsive antigravity region extending out beyond the renormalized Schwarzschild horizon. If the strength of this repulsive force increases as higher orders in the back reaction are included, the formation of a wormholelike object could occur.

Lattice implementation of Abelian gauge theories with Chern-Simons number and an axion field

NASA Astrophysics Data System (ADS)

Figueroa, Daniel G.; Shaposhnikov, Mikhail

2018-01-01

Real time evolution of classical gauge fields is relevant for a number of applications in particle physics and cosmology, ranging from the early Universe to dynamics of quark-gluon plasma. We present an explicit non-compact lattice formulation of the interaction between a shift-symmetric field and some U (1) gauge sector, a (x)FμνF˜μν, reproducing the continuum limit to order O (dxμ2) and obeying the following properties: (i) the system is gauge invariant and (ii) shift symmetry is exact on the lattice. For this end we construct a definition of the topological number density K =FμνF˜μν that admits a lattice total derivative representation K = Δμ+ Kμ, reproducing to order O (dxμ2) the continuum expression K =∂μKμ ∝ E → ṡ B → . If we consider a homogeneous field a (x) = a (t), the system can be mapped into an Abelian gauge theory with Hamiltonian containing a Chern-Simons term for the gauge fields. This allow us to study in an accompanying paper the real time dynamics of fermion number non-conservation (or chirality breaking) in Abelian gauge theories at finite temperature. When a (x) = a (x → , t) is inhomogeneous, the set of lattice equations of motion do not admit however a simple explicit local solution (while preserving an O (dxμ2) accuracy). We discuss an iterative scheme allowing to overcome this difficulty.

Fluctuating pressures in flow fields of jets

NASA Technical Reports Server (NTRS)

Schroeder, J. C.; Haviland, J. K.

1976-01-01

The powered lift configurations under present development for STOL aircraft are the externally blown flap (EBF), involving direct jet impingement on the aircraft flaps, and the upper surface blown (USB), where the jet flow is attached on the upper surface of the wing and directed downwards. Towards the goal of developing scaling laws to predict unsteady loads imposed on the structural components of these STOL aircraft from small model tests, the near field fluctuating pressure behavior for the simplified cases of a round free cold jet and the same jet impinging on a flat plate was investigated. Examples are given of coherences, phase lags (giving convection velocities), and overall fluctuating pressure levels measured. The fluctuating pressure levels measured on the flat plate are compared to surface fluctuating pressure levels measured on full-scale powered-lift configuration models.

[The Characteristic Research of ·OH Induced by Water on an Argon Plasma Jet].

PubMed

Liu, Kun; Liao, Hua; Zheng, Pei-chao; Wang, Chen-ying; Liu, Hong-di; Danil, Dobrynin

2015-07-01

·OH plays a crucial role in many fields, having aroused wide public concern in the world. Atmospheric Pressure Plasma Jet, which can be achieved by portable device due to working without the vacuum environment, has the advantages of high concentration of reactive species, high electron temperature and low gas temperature. It has become an important research topic in the field of gas discharge with a strong prospect. Especially, how to induce plasma jet to produce ·OH has become a new hotpot in the field of low-temperature plasma. It has been reported that mass ·OH can be induced successfully when water vapor is added to the working gas, but it will be unstable when the concentrate of water reaches a certain degree. Thus, a device of argon plasma jet with a Ring-to-Ring Electrode Configuration has been designed to interact with water in the surrounding air to generate ·OH under atmospheric pressure. In order to increase the production of ·OH, ultrasonic atomizing device is introduced to promote water concentration around the plasma plume. The generating rule of OH(A2J) induced by water has been extensively studied under different voltages and flow rate. ·OH output induced by the plasma has been tested by emission spectrometry, and at the meanwhile, Ar atomic spectral lines at 810.41 and 811.48 nm are also recorded in order to calculate the electron temperature in argon plasma plume. The results show that the water surrounding the plasma plume can be induced to produce ·OH, and OH(A2 ∑+) output increases with the electrode voltage rising from 20 to 28 kV. When the flow rate increases from 100 to 200 L x h(-1), the OH(A2∑+) output increases, but from 200 to 600 L x h(-1), it decreases. The production rules of OH(A2∑+) is the same as that of electron temperature. Therefore, the presumption is proved that ·OH output mainly affected by electron temperature.

Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Mizuno, Y.

2005-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created by relativistic pair jets are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Driving a Superconductor to Insulator Transition with Random Gauge Fields.

PubMed

Nguyen, H Q; Hollen, S M; Shainline, J; Xu, J M; Valles, J M

2016-11-30

Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition at a critical level of this gauge field disorder in a nano-patterned array of amorphous Bi islands. This transition shows signs of metallic transport near the critical point characterized by a resistance , indicative of a quantum phase transition. The critical disorder depends on interisland coupling in agreement with recent Quantum Monte Carlo simulations. We discuss how this disorder tuned SIT differs from the common frustration tuned SIT that also occurs in magnetic fields. Its discovery enables new high fidelity comparisons between theoretical and experimental studies of disorder effects on quantum critical systems.

Confining and repulsive potentials from effective non-Abelian gauge fields in graphene bilayers

NASA Astrophysics Data System (ADS)

González, J.

2016-10-01

We investigate the effect of shear and strain in graphene bilayers, under conditions where the distortion of the lattice gives rise to a smooth one-dimensional modulation in the stacking sequence of the bilayer. We show that strain and shear produce characteristic Moiré patterns which can have the same visual appearance on a large scale, but representing graphene bilayers with quite different electronic properties. The different features in the low-energy electronic bands can be ascribed to the effect of a fictitious non-Abelian gauge field mimicking the smooth modulation of the stacking order. Strained and sheared bilayers show a complementary behavior, which can be understood from the fact that the non-Abelian gauge field acts as a repulsive interaction in the former, expelling the electron density away from the stacking domain walls, while behaving as a confining interaction leading to localization of the electronic states in the sheared bilayers. In this latter case, the presence of the effective gauge field explains the development of almost flat low-energy bands, resembling the form of the zeroth Landau level characteristic of a Dirac fermion field. The estimate of the gauge field strength in those systems gives a magnitude of the order of several tens of tesla, implying a robust phenomenology that should be susceptible of being observed in suitably distorted bilayer samples.

Radiation-like scalar field and gauge fields in cosmology for a theory with dynamical time

NASA Astrophysics Data System (ADS)

Benisty, David; Guendelman, E. I.

2016-09-01

Cosmological solutions with a scalar field behaving as radiation are obtained, in the context of gravitational theory with dynamical time. The solution requires the spacial curvature of the universe k, to be zero, unlike the standard radiation solutions, which do not impose any constraint on the spatial curvature of the universe. This is because only such k = 0 radiation solutions pose a homothetic Killing vector. This kind of theory can be used to generalize electromagnetism and other gauge theories, in curved spacetime, and there are no deviations from standard gauge field equation (like Maxwell equations) in the case there exist a conformal Killing vector. But there could be departures from Maxwell and Yang-Mills equations, for more general spacetimes.

Synchronized LES for acoustic near-field analysis of a supersonic jet

NASA Astrophysics Data System (ADS)

S, Unnikrishnan; Gaitonde, Datta; The Ohio State University Team

2014-11-01

We develop a novel method using simultaneous, synchronized Large Eddy Simulations (LES) to examine the manner in which the plume of a supersonic jet generates the near acoustic field. Starting from a statistically stationary state, at each time-step, the first LES (Baseline) is used to obtain native perturbations, which are then localized in space, scaled to small values and injected into the second LES (Twin). At any subsequent time, the difference between the two simulations can be processed to discern how disturbances from any particular zone in the jet are modulated and filtered by the non-linear core to form the combined hydrodynamic and acoustic near field and the fully acoustic farfield. Unlike inverse techniques that use correlations between jet turbulence and far-field signals to infer causality, the current forward analysis effectively tags and tracks native perturbations as they are processed by the jet. Results are presented for a Mach 1.3 cold jet. Statistical analysis of the baseline and perturbation boost provides insight into different mechanisms of disturbance propagation, amplification, directivity, generation of intermittent wave-packet like events and the direct and indirect effect of different parts of the jet on the acoustic field. Office of Naval Research.

Existence of topological multi-string solutions in Abelian gauge field theories

NASA Astrophysics Data System (ADS)

Han, Jongmin; Sohn, Juhee

2017-11-01

In this paper, we consider a general form of self-dual equations arising from Abelian gauge field theories coupled with the Einstein equations. By applying the super/subsolution method, we prove that topological multi-string solutions exist for any coupling constant, which improves previously known results. We provide two examples for application: the self-dual Einstein-Maxwell-Higgs model and the gravitational Maxwell gauged O(3) sigma model.

Two-jet astrosphere model: effect of azimuthal magnetic field

NASA Astrophysics Data System (ADS)

Golikov, E. A.; Izmodenov, V. V.; Alexashov, D. B.; Belov, N. A.

2017-01-01

Opher et al., Drake, Swisdak and Opher have shown that the heliospheric magnetic field results in formation of two-jet structure of the solar wind flow in the inner heliosheath, I.e. in the subsonic region between the heliospheric termination shock (TS) and the heliopause. In this scenario, the heliopause has a tube-like topology as compared with a sheet-like topology in the most models of the global heliosphere. In this paper, we explore the two-jet scenario for a simplified astrosphere in which (1) the star is at rest with respect to the circumstellar medium, (2) radial magnetic field is neglected as compared with azimuthal component and (3) the stellar wind outflow is assumed to be hypersonic (both the Mach number and the Alfvénic Mach number are much greater than unity at the inflow boundary). We have shown that the problem can be formulated in dimensionless form, in which the solution depends only on one dimensionless parameter ɛ that is reciprocal of the Alfvénic Mach number at the inflow boundary. This parameter is proportional to stellar magnetic field. We present the numerical solution of the problem for various values of ɛ. Three first integrals of the governing ideal magnetohydrodynamic equations are presented, and we make use of them in order to get the plasma distribution in the jets. Simple relations between distances to the TS, astropause and the size of the jet are established. These relations allow us to determine the stellar magnetic field from the geometrical pattern of the jet-like astrosphere.

Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

2006-01-01

We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

Noncontractible hyperloops in gauge models with Higgs fields in the fundamental representation

NASA Astrophysics Data System (ADS)

Burzlaff, Jürgen

1984-11-01

We study finite-energy configurations in SO( N) gauge theories with Higgs fields in the fundamental representation. For all winding numbers, noncontractible hyperloops are constructed. The corresponding energy density is spherically symmetric, and the configuration with maximal energy on each hyperloop can be determined. Noncontractible hyperloops with an arbitrary winding number for SU(2) gauge theory are also given.

Laser-induced jet formation in liquid films

NASA Astrophysics Data System (ADS)

Brasz, Frederik; Arnold, Craig

2014-11-01

The absorption of a focused laser pulse in a liquid film generates a cavitation bubble on which a narrow jet can form. This is the basis of laser-induced forward transfer (LIFT), a versatile printing technique that offers an alternative to inkjet printing. We study the influence of the fluid properties and laser pulse energy on jet formation using numerical simulations and time-resolved imaging. At low energies, surface tension causes the jet to retract without transferring a drop, and at high energies, the bubble breaks up into a splashing spray. We explore the parameter space of Weber number, Ohnesorge number, and ratio of film thickness to maximum bubble radius, revealing regions where uniform drops are transferred.

Modeling MHD accretion-ejection: episodic ejections of jets triggered by a mean-field disk dynamo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stepanovs, Deniss; Fendt, Christian; Sheikhnezami, Somayeh, E-mail: deniss@stepanovs.org, E-mail: fendt@mpia.de

2014-11-20

We present MHD simulations exploring the launching, acceleration, and collimation of jets and disk winds. The evolution of the disk structure is consistently taken into account. Extending our earlier studies, we now consider the self-generation of the magnetic field by an α{sup 2}Ω mean-field dynamo. The disk magnetization remains on a rather low level, which helps to evolve the simulations for T > 10, 000 dynamical time steps on a domain extending 1500 inner disk radii. We find the magnetic field of the inner disk to be similar to the commonly found open field structure, favoring magneto-centrifugal launching. The outermore » disk field is highly inclined and predominantly radial. Here, differential rotation induces a strong toroidal component, which plays a key role in outflow launching. These outflows from the outer disk are slower, denser, and less collimated. If the dynamo action is not quenched, magnetic flux is continuously generated, diffuses outward through the disk, and fills the entire disk. We have invented a toy model triggering a time-dependent mean-field dynamo. The duty cycles of this dynamo lead to episodic ejections on similar timescales. When the dynamo is suppressed as the magnetization falls below a critical value, the generation of the outflows and also accretion is inhibited. The general result is that we can steer episodic ejection and large-scale jet knots by a disk-intrinsic dynamo that is time-dependent and regenerates the jet-launching magnetic field.« less

Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Hardee, P.; Hededal, C.; Mizuno, Yosuke; Fishman, G. Jerry; Hartmann, D. H.

2006-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), supernova remnants, and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that particle acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration' is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different spectral properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations of relativistic jets and try to make a connection with observations.

Field-theory representation of gauge-gravity symmetry-protected topological invariants, group cohomology, and beyond.

PubMed

Wang, Juven C; Gu, Zheng-Cheng; Wen, Xiao-Gang

2015-01-23

The challenge of identifying symmetry-protected topological states (SPTs) is due to their lack of symmetry-breaking order parameters and intrinsic topological orders. For this reason, it is impossible to formulate SPTs under Ginzburg-Landau theory or probe SPTs via fractionalized bulk excitations and topology-dependent ground state degeneracy. However, the partition functions from path integrals with various symmetry twists are universal SPT invariants, fully characterizing SPTs. In this work, we use gauge fields to represent those symmetry twists in closed spacetimes of any dimensionality and arbitrary topology. This allows us to express the SPT invariants in terms of continuum field theory. We show that SPT invariants of pure gauge actions describe the SPTs predicted by group cohomology, while the mixed gauge-gravity actions describe the beyond-group-cohomology SPTs. We find new examples of mixed gauge-gravity actions for U(1) SPTs in (4+1)D via the gravitational Chern-Simons term. Field theory representations of SPT invariants not only serve as tools for classifying SPTs, but also guide us in designing physical probes for them. In addition, our field theory representations are independently powerful for studying group cohomology within the mathematical context.

Experimental investigation of jet-induced loads on a flat plate in hover out-of-ground effect

NASA Technical Reports Server (NTRS)

Kuhlman, J. M.; Warcup, R. W.

1979-01-01

Effects of varying jet decay rate on jet-induced loads on a flat plate located in the plane of the jet exit perpendicular to the jet axis were investigated using a small-scale laboratory facility. Jet decay rate has been varied through use of two cylindrical centerbodies having either a flat or hemispherical tip, which were submerged various distances below the flat plate jet exit plane. Increased jet decay rate, caused by the presence of a center-body or plug in the jet nozzle, led to an increased jet-induced lift loss on the flat plate. Jet-induced lift losses reached 1 percent of the jet thrust for the quickest jet decay rates for plate areas equal to 100 times the effective jet exit area. The observed lift loss versus jet decay rate trend agreed well with results of previous investigations.

Gauge-invariant formulation of high-field transport in semiconductors

NASA Astrophysics Data System (ADS)

Ciancio, Emanuele; Iotti, Rita C.; Rossi, Fausto

2004-04-01

In this paper we revisit the conventional description of carrier-phonon scattering in the presence of high electric fields by means of a gauge-invariant density-matrix approach. The proposed formulation of the transport problem allows us, on the one hand, to provide a gauge-independent formulation of Fermi’s golden rule; on the other hand, our analysis clearly shows that in the standard treatments of high-field carrier-phonon scattering—also referred to as intracollisional field effect—the possible variation of the basis states has been usually neglected. This is recognized to be the origin of the apparent discrepancy between scalar- and vector-potential treatments of the problem; indeed, a proper account of such contributions leads, in general, to an ill-defined Markov limit in the carrier-phonon interaction process, assigning to the scalar-potential or Wannier-Stark picture a privileged role. The neglect of such Zener-like contributions in the transport equation leads to a wrong estimation of the high-field voltage-current characteristics, and may partially account for the surprisingly good agreement between semiclassical and rigorous quantum-transport calculations previously reported. This is confirmed by fully three-dimensional simulations of charge transport in state-of-the-art semiconductor superlattices, which show a significant current overestimation.

Principles and applications of laser-induced liquid-phase jet-chemical etching

NASA Astrophysics Data System (ADS)

Stephen, Andreas; Metev, Simeon; Vollertsen, Frank

2003-11-01

In this treatment method laser radiation, which is guided from a coaxially expanding liquid jet-stream, locally initiates a thermochemical etching reaction on a metal surface, which leads to selective material removal at high resolution and quality of the treated surface as well as low thermal influence on the workpiece. Electrochemical investigations were performed under focused laser irradiation using a cw-Nd:YAG laser with a maximum power of 15 W and a simultaneous impact of the liquid jet-stream consisting of phosphoric acid with a maximum flow rate of 20 m/s. The time resolved measurements of the electrical potential difference against an electrochemical reference electrode were correlated with the specific processing parameters and corresponding etch rates to identify processing conditions for temporally stable and enhanced chemical etching reactions. Applications of laser-induced liquid-phase jet-chemical etching in the field of sensor technology, micromechanics and micrmoulding technology are presented. This includes the microstructuring of thin film systems, cutting of foils of shape memory alloys or the generation of structures with defined shape in bulk material.

Computer programs to predict induced effects of jets exhausting into a crossflow

NASA Technical Reports Server (NTRS)

Perkins, S. C., Jr.; Mendenhall, M. R.

1984-01-01

A user's manual for two computer programs was developed to predict the induced effects of jets exhausting into a crossflow. Program JETPLT predicts pressures induced on an infinite flat plate by a jet exhausting at angles to the plate and Program JETBOD, in conjunction with a panel code, predicts pressures induced on a body of revolution by a jet exhausting normal to the surface. Both codes use a potential model of the jet and adjacent surface with empirical corrections for the viscous or nonpotential effects. This program manual contains a description of the use of both programs, instructions for preparation of input, descriptions of the output, limitations of the codes, and sample cases. In addition, procedures to extend both codes to include additional empirical correlations are described.

Double gauge invariance and covariantly-constant vector fields in Weyl geometry

NASA Astrophysics Data System (ADS)

Kassandrov, Vladimir V.; Rizcallah, Joseph A.

2014-08-01

The wave equation and equations of covariantly-constant vector fields (CCVF) in spaces with Weyl nonmetricity turn out to possess, in addition to the canonical conformal-gauge, a gauge invariance of another type. On a Minkowski metric background, the CCVF system alone allows us to pin down the Weyl 4-metricity vector, identified herein with the electromagnetic potential. The fundamental solution is given by the ordinary Lienard-Wiechert field, in particular, by the Coulomb distribution for a charge at rest. Unlike the latter, however, the magnitude of charge is necessarily unity, "elementary", and charges of opposite signs correspond to retarded and advanced potentials respectively, thus establishing a direct connection between the particle/antiparticle asymmetry and the "arrow of time".

Gravitational Scattering Amplitudes and Closed String Field Theory in the Proper-Time Gauge

NASA Astrophysics Data System (ADS)

Lee, Taejin

2018-01-01

We construct a covariant closed string field theory by extending recent works on the covariant open string field theory in the proper-time gauge. Rewriting the string scattering amplitudes generated by the closed string field theory in terms of the Polyakov string path integrals, we identify the Fock space representations of the closed string vertices. We show that the Fock space representations of the closed string field theory may be completely factorized into those of the open string field theory. It implies that the well known Kawai-Lewellen-Tye (KLT) relations of the first quantized string theory may be promoted to the second quantized closed string theory. We explicitly calculate the scattering amplitudes of three gravitons by using the closed string field theory in the proper-time gauge.

Gauge symmetries of the free supersymmetric string field theories

NASA Astrophysics Data System (ADS)

Neveu, A.; West, P. C.

1985-12-01

The gauge covariant local formulations of the free supersymmetric strings that contained a finite number of supplementary fields are extended so as to place all the generators of the Ramond-Neveu-Schwarz algebra on a more equal footing. Permanent address: King's College, Mathematics Department, London WC2R 2LS, UK.

Extended gauge theory and gauged free differential algebras

NASA Astrophysics Data System (ADS)

Salgado, P.; Salgado, S.

2018-01-01

Recently, Antoniadis, Konitopoulos and Savvidy introduced, in the context of the so-called extended gauge theory, a procedure to construct background-free gauge invariants, using non-abelian gauge potentials described by higher degree forms. In this article it is shown that the extended invariants found by Antoniadis, Konitopoulos and Savvidy can be constructed from an algebraic structure known as free differential algebra. In other words, we show that the above mentioned non-abelian gauge theory, where the gauge fields are described by p-forms with p ≥ 2, can be obtained by gauging free differential algebras.

Analysis of stratified and closely spaced jets exhausting into a crossflow. [aerodynamic characteristics of lift-jet, vectored thrust, and lift fan V/STOL aircraft

NASA Technical Reports Server (NTRS)

Ziegler, H.; Woller, P. T.

1973-01-01

Procedures have been developed for determining the flow field about jets with velocity stratification exhausting into a crossflow. Jets with three different types of exit velocity stratification have been considered: (1) jets with a relatively high velocity core; (2) jets with a relatively low velocity core; and (3) jets originating from a vaned nozzle. The procedure developed for a jet originating from a high velocity core nozzle is to construct an equivalent nozzle having the same mass flow and thrust but having a uniform exit velocity profile. Calculations of the jet centerline and induced surface static pressures have been shown to be in good agreement with test data for a high velocity core nozzle. The equivalent ideal nozzle has also been shown to be a good representation for jets with a relatively low velocity core and for jets originating from a vaned nozzle in evaluating jet-induced flow fields. For the singular case of a low velocity core nozzle, namely a nozzle with a dead air core, and for the vaned nozzle, an alternative procedure has been developed. The internal mixing which takes place in the jet core has been properly accounted for in the equations of motion governing the jet development. Calculations of jet centerlines and induced surface static pressures show good agreement with test data these nozzles.

Gauge field entanglement in Kitaev's honeycomb model

NASA Astrophysics Data System (ADS)

Dóra, Balázs; Moessner, Roderich

2018-01-01

A spin fractionalizes into matter and gauge fermions in Kitaev's spin liquid on the honeycomb lattice. This follows from a Jordan-Wigner mapping to fermions, allowing for the construction of a minimal entropy ground-state wave function on the cylinder. We use this to calculate the entanglement entropy by choosing several distinct partitionings. First, by partitioning an infinite cylinder into two, the -ln2 topological entanglement entropy is reconfirmed. Second, the reduced density matrix of the gauge sector on the full cylinder is obtained after tracing out the matter degrees of freedom. This allows for evaluating the gauge entanglement Hamiltonian, which contains infinitely long-range correlations along the symmetry axis of the cylinder. The matter-gauge entanglement entropy is (Ny-1 )ln2 , with Ny the circumference of the cylinder. Third, the rules for calculating the gauge sector entanglement of any partition are determined. Rather small correctly chosen gauge partitions can still account for the topological entanglement entropy in spite of long-range correlations in the gauge entanglement Hamiltonian.

Particle acceleration magnetic field generation, and emission in Relativistic pair jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Kouveliotou, C.; Fishman, G. J.

2005-01-01

Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) are responsible for particle acceleration in relativistic pair jets. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic pair jet propagating through a pair plasma. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. Simulation results show that this instability generates and amplifies highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter' I radiation from deflected electrons can have different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. The growth rate of the Weibel instability and the resulting particle acceleration depend on the magnetic field strength and orientation, and on the initial particle distribution function. In this presentation we explore some of the dependencies of the Weibel instability and resulting particle acceleration on the magnetic field strength and orientation, and the particle distribution function.

Time evolution of linearized gauge field fluctuations on a real-time lattice

NASA Astrophysics Data System (ADS)

Kurkela, A.; Lappi, T.; Peuron, J.

2016-12-01

Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Due to instabilities, small quantum fluctuations on top of the classical background may significantly affect the dynamics of the system. In this paper we argue for the need for a numerical calculation of a system of classical gauge fields and small linearized fluctuations in a way that keeps the separation between the two manifest. We derive and test an explicit algorithm to solve these equations on the lattice, maintaining gauge invariance and Gauss' law.

Mass-loss rates, ionization fractions, shock velocities, and magnetic fields of stellar jets

NASA Technical Reports Server (NTRS)

Hartigan, Patrick; Morse, Jon A.; Raymond, John

1994-01-01

In this paper we calculate emission-line ratios from a series of planar radiative shock models that cover a wide range of shock velocities, preshock densities, and magnetic fields. The models cover the initial conditions relevant to stellar jets, and we show how to estimate the ionization fractions and shock velocities in jets directly from observations of the strong emission lines in these flows. The ionization fractions in the HH 34, HH 47, and HH 111 jets are approximately 2%, considerably smaller than previous estimates, and the shock velocities are approximately 30 km/s. For each jet the ionization fractions were found from five different line ratios, and the estimates agree to within a factor of approximately 2. The scatter in the estimates of the shock velocities is also small (+/- 4 km/s). The low ionization fractions of stellar jets imply that the observed electron densities are much lower than the total densities, so the mass-loss rates in these flows are correspondingly higher (approximately greater than 2 x 10(exp -7) solar mass/yr). The mass-loss rates in jets are a significant fraction (1%-10%) of the disk accretion rates onto young stellar objects that drive the outflows. The momentum and energy supplied by the visible portion of a typical stellar jet are sufficient to drive a weak molecular outflow. Magnetic fields in stellar jets are difficult to measure because the line ratios from a radiative shock with a magnetic field resemble those of a lower velocity shock without a field. The observed line fluxes can in principle indicate the strength of the field if the geometry of the shocks in the jet is well known.

Gauge and Non-Gauge Tensor Multiplets in 5D Conformal Supergravity

NASA Astrophysics Data System (ADS)

Kugo, T.; Ohashi, K.

2002-12-01

An off-shell formulation of two distinct tensor multiplets, a massive tensor multiplet and a tensor gauge multiplet, is presented in superconformal tensor calculus in five-dimensional space-time. Both contain a rank 2 antisymmetric tensor field, but there is no gauge symmetry in the former, while it is a gauge field in the latter. Both multiplets have 4 bosonic and 4 fermionic on-shell modes, but the former consists of 16 (boson)+16 (fermion) component fields, while the latter consists of 8 (boson)+8 (fermion) component fields.

Enveloping algebra-valued gauge transformations for non-abelian gauge groups on non-commutative spaces

NASA Astrophysics Data System (ADS)

Jurco, B.; Schraml, S.; Schupp, P.; Wess, J.

2000-11-01

An enveloping algebra-valued gauge field is constructed, its components are functions of the Lie algebra-valued gauge field and can be constructed with the Seiberg-Witten map. This allows the formulation of a dynamics for a finite number of gauge field components on non-commutative spaces.

Gas dynamics of a supersonic radial jet. Part II

NASA Astrophysics Data System (ADS)

Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

2016-05-01

The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K. I.; Hardee, P.; Hededal, C. B.; Richardson, G.; Sol, H.; Preece, R.; Fishman, G. J.

2004-01-01

Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating into an ambient plasma. We find that the growth times depend on the Lorenz factors of jets. The jets with larger Lorenz factors grow slower. Simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The small scale magnetic field structure generated by the Weibel instability is appropriate to the generation of "jitter" radiation from deflected electrons (positrons) as opposed to synchrotron radiation. The jitter radiation resulting from small scale magnetic field structures may be important for understanding the complex time structure and spectral evolution observed in gamma-ray bursts or other astrophysical sources containing relativistic jets and relativistic collisionless shocks.

The Driving Magnetic Field and Reconnection in CME/Flare Eruptions and Coronal Jets

NASA Technical Reports Server (NTRS)

Moore, Ronald L.

2010-01-01

Signatures of reconnection in major CME (coronal mass ejection)/flare eruptions and in coronal X-ray jets are illustrated and interpreted. The signatures are magnetic field lines and their feet that brighten in flare emission. CME/flare eruptions are magnetic explosions in which: 1. The field that erupts is initially a closed arcade. 2. At eruption onset, most of the free magnetic energy to be released is not stored in field bracketing a current sheet, but in sheared field in the core of the arcade. 3. The sheared core field erupts by a process that from its start or soon after involves fast "tether-cutting" reconnection at an initially small current sheet low in the sheared core field. If the arcade has oppositely-directed field over it, the eruption process from its start or soon after also involves fast "breakout" reconnection at an initially small current sheet between the arcade and the overarching field. These aspects are shown by the small area of the bright field lines and foot-point flare ribbons in the onset of the eruption. 4. At either small current sheet, the fast reconnection progressively unleashes the erupting core field to erupt with progressively greater force. In turn, the erupting core field drives the current sheet to become progressively larger and to undergo progressively greater fast reconnection in the explosive phase of the eruption, and the flare arcade and ribbons grow to become comparable to the pre-eruption arcade in lateral extent. In coronal X-ray jets: 1. The magnetic energy released in the jet is built up by the emergence of a magnetic arcade into surrounding unipolar "open" field. 2. A simple jet is produced when a burst of reconnection occurs at the current sheet between the arcade and the open field. This produces a bright reconnection jet and a bright reconnection arcade that are both much smaller in diameter that the driving arcade. 3. A more complex jet is produced when the arcade has a sheared core field and undergoes an

Tunable axial gauge fields in engineered Weyl semimetals: semiclassical analysis and optical lattice implementations

NASA Astrophysics Data System (ADS)

Roy, Sthitadhi; Kolodrubetz, Michael; Goldman, Nathan; Grushin, Adolfo G.

2018-04-01

In this work, we describe a toolbox to realize and probe synthetic axial gauge fields in engineered Weyl semimetals. These synthetic electromagnetic fields, which are sensitive to the chirality associated with Weyl nodes, emerge due to spatially and temporally dependent shifts of the corresponding Weyl momenta. First, we introduce two realistic models, inspired by recent cold-atom developments, which are particularly suitable for the exploration of these synthetic axial gauge fields. Second, we describe how to realize and measure the effects of such axial fields through center-of-mass observables, based on semiclassical equations of motion and exact numerical simulations. In particular, we suggest realistic protocols to reveal an axial Hall response due to the axial electric field \

Reconnection and Associated Flares in Global Relativistic Jets Containing Helical Magnetic Fields with PIC Simulations

NASA Astrophysics Data System (ADS)

Nishikawa, Ken-Ichi; Hartmann, Dieter; Mizuno, Yosuke; Niemiec, Jacek; Dutan, Ioana; Kobzar, Oleh; Gomez, Jose; Meli, Athina; POHL, Martin

2018-01-01

In the study of relativistic jets one of the key open questions is their interaction with theenvironment on the microscopic level. Here, we study the initial evolution of both electron–proton and electron–positron relativistic jets containing helical magnetic fields, focusing on their interaction with an ambient plasma. We have performed simulations of “global” jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability (kKHI) and the Mushroom instability (MI) using a larger jet radius. In our initial simulation study these kinetic instabilities are suppressed and new types of instabilities can grow. In the electron-proton jet simulation a recollimation-like instability occurs near the center of jet. In the electron-positron jet simulation mixed kinetic instabilities grow and the jet electrons are accelerated. The evolution of electron-ion jets will be investigated with different mass ratios. Simulations using much larger systems are required in order to thoroughly follow the evolution of global jets containing helical magnetic fields. We will investigate mechanisms of flares possibly due to reconnection.

Jet engine noise and infrared plume correlation field campaign

NASA Astrophysics Data System (ADS)

Cunio, Phillip M.; Weber, Reed A.; Knobel, Kimberly R.; Smith, Christine; Draudt, Andy

2015-09-01

Jet engine noise can be a health hazard and environmental pollutant, particularly affecting personnel working in close proximity to jet engines, such as airline mechanics. Mitigating noise could reduce the potential for hearing loss in runway workers; however, there exists a very complex relationship between jet engine design parameters, operating conditions, and resultant noise power levels, and understanding and characterizing this relationship is a key step in mitigating jet engine noise effects. We demonstrate initial results highlighting the utility of high-speed imaging (hypertemporal imaging) in correlating the infrared signatures of jet engines with acoustic noise. This paper builds on prior theoretical analysis of jet engine infrared signatures and their potential relationships to jet engine acoustic emissions. This previous work identified the region of the jet plume most likely to emit both in infrared and in acoustic domains, and it prompted the investigation of wave packets as a physical construct tying together acoustic and infrared energy emissions. As a means of verifying these assertions, a field campaign to collect relevant data was proposed, and data collection was carried out with a bank of infrared instruments imaging a T700 turboshaft engine undergoing routine operational testing. The detection of hypertemporal signatures in association with acoustic signatures of jet engines enables the use of a new domain in characterizing jet engine noise. This may in turn enable new methods of predicting or mitigating jet engine noise, which could lead to socioeconomic benefits for airlines and other operators of large numbers of jet engines.

Absolute atomic oxygen density measurements for nanosecond-pulsed atmospheric-pressure plasma jets using two-photon absorption laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Jiang, C.; Carter, C.

2014-12-01

Nanosecond-pulsed plasma jets that are generated under ambient air conditions and free from confinement of electrodes have become of great interest in recent years due to their promising applications in medicine and dentistry. Reactive oxygen species that are generated by nanosecond-pulsed, room-temperature non-equilibrium He-O2 plasma jets among others are believed to play an important role during the bactericidal or sterilization processes. We report here absolute measurements of atomic oxygen density in a 1 mm-diameter He/(1%)O2 plasma jet at atmospheric pressure using two-photon absorption laser-induced fluorescence spectroscopy. Oxygen number density on the order of 1013 cm-3 was obtained in a 150 ns, 6 kV single-pulsed plasma jet for an axial distance up to 5 mm above the device nozzle. Temporally resolved O density measurements showed that there are two maxima, separated in time by 60-70 µs, and a total pulse duration of 260-300 µs. Electrostatic modeling indicated that there are high-electric-field regions near the nozzle exit that may be responsible for the observed temporal behavior of the O production. Both the field-distribution-based estimation of the time interval for the O number density profile and a pulse-energy-dependence study confirmed that electric-field-dependent, direct and indirect electron-induced processes play important roles for O production.

Platelet activating factor receptor binding plays a critical role in jet fuel-induced immune suppression.

PubMed

Ramos, Gerardo; Kazimi, Nasser; Nghiem, Dat X; Walterscheid, Jeffrey P; Ullrich, Stephen E

2004-03-15

Applying military jet fuel (JP-8) or commercial jet fuel (Jet-A) to the skin of mice suppresses the immune response in a dose-dependent manner. The release of biological response modifiers, particularly prostaglandin E2 (PGE2), is a critical step in activating immune suppression. Previous studies have shown that injecting selective cyclooxygenase-2 inhibitors into jet fuel-treated mice blocks immune suppression. Because the inflammatory phospholipid mediator, platelet-activating factor (PAF), up-regulates cyclooxygenase-2 production and PGE2 synthesis by keratinocytes, we tested the hypothesis that PAF-receptor binding plays a role in jet fuel-induced immune suppression. Treating keratinocyte cultures with PAF and/or jet fuel (JP-8 and Jet-A) stimulates PGE2 secretion. Jet fuel-induced PGE2 production was suppressed by treating the keratinocytes with specific PAF-receptor antagonists. Injecting mice with PAF, or treating the skin of the mice with JP-8, or Jet-A, induced immune suppression. Jet fuel-induced immune suppression was blocked when the jet fuel-treated mice were injected with PAF-receptor antagonists before treatment. Jet fuel treatment has been reported to activate oxidative stress and treating the mice with anti-oxidants (Vitamins C, or E or beta-hydroxy toluene), before jet fuel application, interfered with immune suppression. These findings confirm previous studies showing that PAF-receptor binding can modulate immune function. Furthermore, they suggest that PAF-receptor binding may be an early event in the induction of immune suppression by immunotoxic environmental agents that target the skin.

Far Noise Field of Air Jets and Jet Engines

NASA Technical Reports Server (NTRS)

Callaghan, Edmund E; Coles, Willard D

1957-01-01

An experimental investigation was conducted to study and compare the acoustic radiation of air jets and jet engines. A number of different nozzle-exit shapes were studied with air jets to determine the effect of exit shape on noise generation. Circular, square, rectangular, and elliptical convergent nozzles and convergent-divergent and plug nozzles were investigated. The spectral distributions of the sound power for the engine and the air jet were in good agreement for the case where the engine data were not greatly affected by reflection or jet interference effects. Such power spectra for a subsonic or slightly choked engine or air jet show that the peaks of the spectra occur at a Strouhal number of 0.3.

Gauge fields at finite temperatures—"Thermo field dynamics" and the KMS condition and their extension to gauge theories

NASA Astrophysics Data System (ADS)

Ojima, Izumi

1981-11-01

"Thermo field dynamics," allowing the Feynman diagram method to be applied to real-time causal Green's functions at finite temperatures ( not temperature Green's functions with imaginary times) expressed in the form of "vacuum" expectation values, is reconsidered in light of its connection with the algebraic formulation of statical machanics based upon the KMS condition. On the basis of so-obtained general basic formulae, the formalism is extended to the case of gauge theories, where the subsidiary condition specifying physical states, the notion of observables, and the structure of the physical subspace at finite temperatures are clarified.

Mixing and Flow-field Characteristics of Strongly-forced Transitional / Turbulent Jets and Jet Flames

NASA Astrophysics Data System (ADS)

Lakshminarasimhan, Krishna

2005-11-01

Strong pulsations of the fuel flow rate have previously been shown to dramatically alter the flame length and luminosity of nonpremixed jet flames. The mechanisms responsible for such changes are explored experimentally in nonreacting and reacting strongly pulsed jets by using cinematographic PIV and acetone PLIF. The large amplitude forcing was obtained by pulsing the flow using a solenoid valve at the organ-pipe resonance frequency of the fuel delivery tube. The velocity fluctuations in the flow produced by the resonant pulsing of the jet can reach to about 8 times that of the mean flow. The jet characteristics were studied for Reynolds numbers based on mean flow velocity ranging between 800 and 2400. The PIV shows that with strong pulsations the jet exhibits significant reverse flow into the fuel delivery tube and an increase in turbulence in the near-field region. The acetone PLIF imaging was performed inside and outside the fuel tube in order to study the effects of pulsations on the mixing. These measurements showed significant in-tube partial premixing due to the reverse flow near the nozzle exit as well as enhanced mixing due to coherent vortical structures and increased turbulence.

Experiments and modeling of dilution jet flow fields

NASA Technical Reports Server (NTRS)

Holdeman, James D.

1986-01-01

Experimental and analytical results of the mixing of single, double, and opposed rows of jets with an isothermal or variable-temperature main stream in a straight duct are presented. This study was performed to investigate flow and geometric variations typical of the complex, three-dimensional flow field in the dilution zone of gas-turbine-engine combustion chambers. The principal results, shown experimentally and analytically, were the following: (1) variations in orifice size and spacing can have a significant effect on the temperature profiles; (2) similar distributions can be obtained, independent of orifice diameter, if momentum-flux ratio and orifice spacing are coupled; (3) a first-order approximation of the mixing of jets with a variable-temperature main stream can be obtained by superimposing the main-stream and jets-in-an-isothermal-crossflow profiles; (4) the penetration of jets issuing mixing is slower and is asymmetric with respect to the jet centerplanes, which shift laterally with increasing downstream distance; (5) double rows of jets give temperature distributions similar to those from a single row of equally spaced, equal-area circular holes; (6) for opposed rows of jets, with the orifice centerlines in line, the optimum ratio of orifice spacing to duct height is one-half the optimum value for single-side injection at the same momentum-flux ratiol and (7) for opposed rows of jets, with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is twice the optimum value for single-side injection at the same momentum-flux ratio.

Criteria for disintegration of an uncharged conducting liquid jet in a transverse electric field

NASA Astrophysics Data System (ADS)

Zubareva, O. V.; Zubarev, N. M.; Volkov, N. B.

2018-01-01

An uncharged conducting liquid cylindrical column (a jet for applications) placed between a pair of flat electrodes is considered. In the trivial case, when the electric field is absent, the jet with circular cross-section is the only possible equilibrium configuration of the system. In the presence of a potential difference between the electrodes, the jet is deformed by the electrostatic forces: its cross-section stretches along the electric field lines. In the case of the mutual compensation of the electrostatic and capillary forces, a new equilibrium configuration of the jet can appear. In a sufficiently strong field, the balance of the forces becomes impossible, and the jet disintegrates (splits into two separate jets). In the present work, we find the range of the parameters (the applied potential difference and the interelectrode distance), where the problem of finding the equilibrium configurations of the jet has solutions. Also we obtain the conditions under which the solutions do not exist and, consequently, the jet splits. The results are compared with the previously studied limiting case of infinite interelectrode distance.

Particle Acceleration, Magnetic Field Generation, and Associated Emission in Collisionless Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.

2007-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron)jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Particle Acceleration, Magnetic Field Generation and Associated Emission in Collisionless Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K. I.; Ramirez-Ruiz, E.; Hardee, P.; Mizuno, Y.; Fishman. G. J.

2007-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Gauge Fields in Homogeneous and Inhomogeneous Cosmologies

NASA Astrophysics Data System (ADS)

Darian, Bahman K.

Despite its formidable appearance, the study of classical Yang-Mills (YM) fields on homogeneous cosmologies is amenable to a formal treatment. This dissertation is a report on a systematic approach to the general construction of invariant YM fields on homogeneous cosmologies undertaken for the first time in this context. This construction is subsequently followed by the investigation of the behavior of YM field variables for the most simple of self-gravitating YM fields. Particularly interesting was a dynamical system analysis and the discovery of chaotic signature in the axially symmetric Bianchi I-YM cosmology. Homogeneous YM fields are well studied and are known to have chaotic properties. The chaotic behavior of YM field variables in homogeneous cosmologies might eventually lead to an invariant definition of chaos in (general) relativistic cosmological models. By choosing the gauge fields to be Abelian, the construction and the field equations presented so far reduce to that of electromagnetic field in homogeneous cosmologies. A perturbative analysis of gravitationally interacting electromagnetic and scalar fields in inhomogeneous cosmologies is performed via the Hamilton-Jacobi formulation of general relativity. An essential feature of this analysis is the spatial gradient expansion of the generating functional (Hamilton principal function) to solve the Hamiltonian constraint. Perturbations of a spatially flat Friedman-Robertson-Walker cosmology with an exponential potential for the scalar field are presented.

Real jet effects on dual jets in a crossflow

NASA Technical Reports Server (NTRS)

Schetz, J. A.

1984-01-01

A 6-ft by 6-ft wind tunnel section was modification to accommodate the 7-ft wide NASA dual-jet flate model in an effort to determine the effects of nonuniform and/or noncircular jet exhaust profiles on the pressure field induced on a nearby surface. Tests completed yield surface pressure measurements for a 90 deg circular injector producing exit profiles representative of turbofan nozzles (such as the TF-34 nozzle). The measurements were obtained for both tandem and side-by-side jet configurations, jet spacing of S/D =2, and velocity ratios of R=2.2 and 4.0. Control tests at the same mass flow rate but with uniform exit velocity profiles were also conducted, for comparison purposes. Plots for 90 deg injection and R=2.2 show that the effects of exit velocity profile nonuniformity are quite significant.

The first law of black hole mechanics for fields with internal gauge freedom

NASA Astrophysics Data System (ADS)

Prabhu, Kartik

2017-02-01

We derive the first law of black hole mechanics for physical theories based on a local, covariant and gauge-invariant Lagrangian where the dynamical fields transform non-trivially under the action of some internal gauge transformations. The theories of interest include General Relativity formulated in terms of tetrads, Einstein-Yang-Mills theory and Einstein-Dirac theory. Since the dynamical fields of these theories have some internal gauge freedom, we argue that there is no natural group action of diffeomorphisms of spacetime on such dynamical fields. In general, such fields cannot even be represented as smooth, globally well-defined tensor fields on spacetime. Consequently the derivation of the first law by Iyer and Wald cannot be used directly. Nevertheless, we show how such theories can be formulated on a principal bundle and that there is a natural action of automorphisms of the bundle on the fields. These bundle automorphisms encode both spacetime diffeomorphisms and internal gauge transformations. Using this reformulation we define the Noether charge associated to an infinitesimal automorphism and the corresponding notion of stationarity and axisymmetry of the dynamical fields. We first show that we can define certain potentials and charges at the horizon of a black hole so that the potentials are constant on the bifurcate Killing horizon, giving a generalised zeroth law for bifurcate Killing horizons. We further identify the gravitational potential and perturbed charge as the temperature and perturbed entropy of the black hole which gives an explicit formula for the perturbed entropy analogous to the Wald entropy formula. We then obtain a general first law of black hole mechanics for such theories. The first law relates the perturbed Hamiltonians at spatial infinity and the horizon, and the horizon contributions take the form of a ‘potential times perturbed charge’ term. We also comment on the ambiguities in defining a prescription for the total entropy

Fluid dynamic aspects of jet noise generation. [noise measurement of jet blast effects from supersonic jet flow in convergent-divergent nozzles

NASA Technical Reports Server (NTRS)

Barra, V.; Panunzio, S.

1976-01-01

Jet engine noise generation and noise propagation was investigated by studying supersonic nozzle flow of various nozzle configurations in an experimental test facility. The experimental facility was constructed to provide a coaxial axisymmetric jet flow of unheated air. In the test setup, an inner primary flow exhausted from a 7 in. exit diameter convergent--divergent nozzle at Mach 2, while a secondary flow had a 10 in. outside diameter and was sonic at the exit. The large dimensions of the jets permitted probes to be placed inside the jet core without significantly disturbing the flow. Static pressure fluctuations were measured for the flows. The nozzles were designed for shock free (balanced) flow at Mach 2. Data processing techniques and experimental procedures were developed in order to study induced disturbances at the edge of the supersonic flows, and the propagation of those disturbances throughout the flows. Equipment used (specifications are given) to record acoustic levels (far field noise) is described. Results and conclusions are presented and discussed. Diagrams of the jet flow fields are included along with photographs of the test stand.

Jet in jet in M87

NASA Astrophysics Data System (ADS)

Sob'yanin, Denis Nikolaevich

2017-11-01

New high-resolution Very Long Baseline Interferometer observations of the prominent jet in the M87 radio galaxy show a persistent triple-ridge structure of the transverse 15-GHz profile with a previously unobserved ultra-narrow central ridge. This radio structure can reflect the intrinsic structure of the jet, so that the jet as a whole consists of two embedded coaxial jets. A relativistic magnetohydrodynamic model is considered in which an inner jet is placed inside a hollow outer jet and the electromagnetic fields, pressures and other physical quantities are found. The entire jet is connected to the central engine that plays the role of a unipolar inductor generating voltage between the jets and providing opposite electric currents, and the charge neutrality and current closure together with the electromagnetic fields between the jets can contribute to the jet stabilization. The constant voltage is responsible for the similar widening laws observed for the inner and outer jets. This jet-in-jet structure can indicate simultaneous operation of two different jet-launching mechanisms, one relating to the central supermassive black hole and the other to the surrounding accretion disc. An inferred magnetic field of 80 G at the base is sufficient to provide the observed jet luminosity.

Magnetic field generation in core-sheath jets via the kinetic Kelvin-Helmholtz instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishikawa, K.-I.; Hardee, P. E.; Duţan, I.

2014-09-20

We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas, we find generation of strong large-scale DC currents and magnetic fields that extend over the entire shear surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas, we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shearmore » surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates a transverse structure similar to that produced by the Weibel instability.« less

Covariant open bosonic string field theory on multiple D-branes in the proper-time gauge

NASA Astrophysics Data System (ADS)

Lee, Taejin

2017-12-01

We construct a covariant open bosonic string field theory on multiple D-branes, which reduces to a non-Abelian group Yang-Mills gauge theory in the zero-slope limit. Making use of the first quantized open bosonic string in the proper time gauge, we convert the string amplitudes given by the Polyakov path integrals on string world sheets into those of the second quantized theory. The world sheet diagrams generated by the constructed open string field theory are planar in contrast to those of the Witten's cubic string field theory. However, the constructed string field theory is yet equivalent to the Witten's cubic string field theory. Having obtained planar diagrams, we may adopt the light-cone string field theory technique to calculate the multi-string scattering amplitudes with an arbitrary number of external strings. We examine in detail the three-string vertex diagram and the effective four-string vertex diagrams generated perturbatively by the three-string vertex at tree level. In the zero-slope limit, the string scattering amplitudes are identified precisely as those of non-Abelian Yang-Mills gauge theory if the external states are chosen to be massless vector particles.

Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow baseline and suppressor nozzles. Volume 1: Noise source locations and extrapolation of static free-field jet noise data

NASA Technical Reports Server (NTRS)

Jaeck, C. L.

1976-01-01

A test was conducted in the Boeing Large Anechoic Chamber to determine static jet noise source locations of six baseline and suppressor nozzle models, and establish a technique for extrapolating near field data into the far field. The test covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K.

Numerical and Experimental Determination of the Geometric Far Field for Round Jets

NASA Technical Reports Server (NTRS)

Koch, L. Danielle; Bridges, James; Brown, Cliff; Khavaran, Abbas

2003-01-01

To reduce ambiguity in the reporting of far field jet noise, three round jets operating at subsonic conditions have recently been studied at the NASA Glenn Research Center. The goal of the investigation was to determine the location of the geometric far field both numerically and experimentally. The combination of the WIND Reynolds-Averaged Navier-Stokes solver and the MGBK jet noise prediction code was used for the computations, and the experimental data was collected in the Aeroacoustic Propulsion Laboratory. While noise sources are distributed throughout the jet plume, at great distances from the nozzle the noise will appear to be emanating from a point source and the assumption of linear propagation is valid. Closer to the jet, nonlinear propagation may be a problem, along with the known geometric issues. By comparing sound spectra at different distances from the jet, both from computational methods that assume linear propagation, and from experiments, the contributions of geometry and nonlinearity can be separately ascertained and the required measurement distance for valid experiments can be established. It is found that while the shortest arc considered here (approx. 8D) was already in the geometric far field for the high frequency sound (St greater than 2.0), the low frequency noise due to its extended source distribution reached the geometric far field at or about 50D. It is also found that sound spectra at far downstream angles does not strictly scale on Strouhal number, an observation that current modeling does not capture.

Field assessment of noncontact stream gauging using portable surface velocity radars (SVR)

NASA Astrophysics Data System (ADS)

Welber, Matilde; Le Coz, Jérôme; Laronne, Jonathan B.; Zolezzi, Guido; Zamler, Daniel; Dramais, Guillaume; Hauet, Alexandre; Salvaro, Martino

2016-02-01

The applicability of a portable, commercially available surface velocity radar (SVR) for noncontact stream gauging was evaluated through a series of field-scale experiments carried out in a variety of sites and deployment conditions. Comparisons with various concurrent techniques showed acceptable agreement with velocity profiles, with larger uncertainties close to the banks. In addition to discharge error sources shared with intrusive velocity-area techniques, SVR discharge estimates are affected by flood-induced changes in the bed profile and by the selection of a depth-averaged to surface velocity ratio, or velocity coefficient (α). Cross-sectional averaged velocity coefficients showed smaller fluctuations and closer agreement with theoretical values than those computed on individual verticals, especially in channels with high relative roughness. Our findings confirm that α = 0.85 is a valid default value, with a preferred site-specific calibration to avoid underestimation of discharge in very smooth channels (relative roughness ˜ 0.001) and overestimation in very rough channels (relative roughness > 0.05). Theoretically derived and site-calibrated values of α also give accurate SVR-based discharge estimates (within 10%) for low and intermediate roughness flows (relative roughness 0.001 to 0.05). Moreover, discharge uncertainty does not exceed 10% even for a limited number of SVR positions along the cross section (particularly advantageous to gauge unsteady flood flows and very large floods), thereby extending the range of validity of rating curves.

Enhanced heat sink with geometry induced wall-jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, Md. Mahamudul, E-mail: sohel0991@gmail.com; Tikadar, Amitav; Bari, Fazlul

Mini-channels embedded in solid matrix have already proven to be a very efficient way of electronic cooling. Traditional mini-channel heat sinks consist of single layer of parallel channels. Although mini-channel heat sink can achieve very high heat flux, its pumping requirement for circulating liquid through the channel increase very sharply as the flow velocity increases. The pumping requirements of the heat sink can be reduced by increasing its performance. In this paper a novel approach to increase the thermal performance of the mini-channel heat sink is proposed through geometry induced wall jet which is a passive technique. Geometric irregularities alongmore » the channel length causes abrupt pressure change between the channels which causes cross flow through the interconnections thus one channel faces suction and other channel jet action. This suction and jet action disrupts boundary layer causing enhanced heat transfer performance. A CFD model has been developed using commercially available software package FLUENT to evaluate the technique. A parametric study of the velocities and the effect of the position of the wall-jets have been performed. Significant reduction in thermal resistance has been observed for wall-jets, it is also observed that this reduction in thermal resistance is dependent on the position and shape of the wall jet.« less

Weak gauge boson radiation in parton showers

NASA Astrophysics Data System (ADS)

Christiansen, Jesper R.; Sjöstrand, Torbjörn

2014-04-01

The emission of W and Z gauge bosons off quarks is included in a traditional QCD + QED shower. The unitarity of the shower algorithm links the real radiation of the weak gauge bosons to the negative weak virtual corrections. The shower evolution process leads to a competition between QCD, QED and weak radiation, and allows for W and Z boson production inside jets. Various effects on LHC physics are studied, both at low and high transverse momenta, and effects at higher-energy hadron colliders are outlined.

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

NASA Astrophysics Data System (ADS)

Mehtar-Tani, Yacine; Tywoniuk, Konrad

2017-04-01

We argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the "soft drop declustering" procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, that is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.

On gauge independence for gauge models with soft breaking of BRST symmetry

NASA Astrophysics Data System (ADS)

Reshetnyak, Alexander

2014-12-01

A consistent quantum treatment of general gauge theories with an arbitrary gauge-fixing in the presence of soft breaking of the BRST symmetry in the field-antifield formalism is developed. It is based on a gauged (involving a field-dependent parameter) version of finite BRST transformations. The prescription allows one to restore the gauge-independence of the effective action at its extremals and therefore also that of the conventional S-matrix for a theory with BRST-breaking terms being additively introduced into a BRST-invariant action in order to achieve a consistency of the functional integral. We demonstrate the applicability of this prescription within the approach of functional renormalization group to the Yang-Mills and gravity theories. The Gribov-Zwanziger action and the refined Gribov-Zwanziger action for a many-parameter family of gauges, including the Coulomb, axial and covariant gauges, are derived perturbatively on the basis of finite gauged BRST transformations starting from Landau gauge. It is proved that gauge theories with soft breaking of BRST symmetry can be made consistent if the transformed BRST-breaking terms satisfy the same soft BRST symmetry breaking condition in the resulting gauge as the untransformed ones in the initial gauge, and also without this requirement.

A note on large gauge transformations in double field theory

DOE PAGES

Naseer, Usman

2015-06-03

Here, we give a detailed proof of the conjecture by Hohm and Zwiebach in double field theory. Our result implies that their proposal for large gauge transformations in terms of the Jacobian matrix for coordinate transformations is, as required, equivalent to the standard exponential map associated with the generalized Lie derivative along a suitable parameter.

Radiatively-driven general relativistic jets

NASA Astrophysics Data System (ADS)

Vyas, Mukesh K.; Chattopadhyay, Indranil

2018-02-01

We use moment formalism of relativistic radiation hydrodynamics to obtain equations of motion of radial jets and solve them using polytropic equation of state of the relativistic gas. We consider curved space-time around black holes and obtain jets with moderately relativistic terminal speeds. In addition, the radiation field from the accretion disc, is able to induce internal shocks in the jet close to the horizon. Under combined effect of thermal as well as radiative driving, terminal speeds up to 0.75 (units of light speed) are obtained.

Field-antifield and BFV formalisms for quadratic systems with open gauge algebras

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nirov, K.S.; Razumov, A.V.

1992-09-20

In this paper the Lagrangian field-antifield (BV) and Hamiltonian (BFV) BRST formalisms for the general quadratic systems with open gauge algebra are considered. The equivalence between the Lagrangian and Hamiltonian formalisms is proven.

Confinement Driven by Scalar Field in 4d Non Abelian Gauge Theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chabab, Mohamed

2007-01-12

We review some of the most recent work on confinement in 4d gauge theories with a massive scalar field (dilaton). Emphasis is put on the derivation of confining analytical solutions to the Coulomb problem versus dilaton effective couplings to gauge terms. It is shown that these effective theories can be relevant to model quark confinement and may shed some light on confinement mechanism. Moreover, the study of interquark potential, derived from Dick Model, in the heavy meson sector proves that phenomenological investigation of tmechanism is more than justified and deserves more efforts.

Interfacial gauge methods for incompressible fluid dynamics

DOE PAGES

Saye, R.

2016-06-10

Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of "gauge freedom" to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work,more » high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena.« less

Interfacial gauge methods for incompressible fluid dynamics

PubMed Central

Saye, Robert

2016-01-01

Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of “gauge freedom” to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena. PMID:27386567

An Experimental Study of Plunging Liquid Jet Induced Air Carryunder and Dispersion

DTIC Science & Technology

1991-12-24

the ’ greenhouse ’ effect (ie, the absorption of CO2 by the oceans), and a number of other important maritime-related applications. In particular, the air entrainment process due to the breaking bow waves of surface ships may cause long (ie, up to 5 km in length) wakes. Naturally easily detectable wakes are undesirable for naval warships. In the present study plunging liquid jet experiments were performed and detailed Laser Doppler Anemometer (LDA) data were taken of the phasic velocity field and the void fraction distribution in the induced two-phase

An experimental study of the flow field surrounding a subsonic jet in a cross flow. M.S. Thesis

NASA Technical Reports Server (NTRS)

Dennis, Robert Foster

1993-01-01

An experimental investigation of the flow interaction of a 5.08 cm (2.00 in.) diameter round subsonic jet exhausting perpendicularly to a flat plate in a subsonic cross flow was conducted in the NASA Ames 7x1O ft. Wind Tunnel Number One. Flat plate surface pressures were measured at 400 locations in a 30.48 cm (12.0 in.) concentric circular array surrounding the jet exit. Results from these measurements are provided in tabular and graphical form for jet-to-crossflow velocity ratios ranging from 4 to 12, and for jet exit Mach numbers ranging from 0.50 to 0.93. Laser doppler velocimeter (LDV) three component velocity measurements were made in selected regions in the developed jet plume and near the flat plate surface, at a jet Mach number of 0.50 and jet-to-crossflow velocity ratios of 6 and 8. The results of both pressure and LDV measurements are compared with the results of previous experiments. In addition, pictures of the jet plume shape at jet velocity ratios ranging from 4 to 12 were obtained using schleiren photography. The LDV measurements are consistent with previous work, but more extensive measurements will be necessary to provide a detailed picture of the flow field. The surface pressure results compare closely with previous work and provide a useful characterization of jet induced surface pressures. The results demonstrate the primary influence of jet velocity ratio and the secondary influence of jet Mach number in determining such surface pressures.

Experimental and Analytical Determination of the Geometric Far Field for Round Jets

NASA Technical Reports Server (NTRS)

Koch, L. Danielle; Bridges, James E.; Brown, Clifford E.; Khavaran, Abbas

2005-01-01

An investigation was conducted at the NASA Glenn Research Center using a set of three round jets operating under unheated subsonic conditions to address the question: "How close is too close?" Although sound sources are distributed at various distances throughout a jet plume downstream of the nozzle exit, at great distances from the nozzle the sound will appear to emanate from a point and the inverse-square law can be properly applied. Examination of normalized sound spectra at different distances from a jet, from experiments and from computational tools, established the required minimum distance for valid far-field measurements of the sound from subsonic round jets. Experimental data were acquired in the Aeroacoustic Propulsion Laboratory at the NASA Glenn Research Center. The WIND computer program solved the Reynolds-Averaged Navier-Stokes equations for aerodynamic computations; the MGBK jet-noise prediction computer code was used to predict the sound pressure levels. Results from both the experiments and the analytical exercises indicated that while the shortest measurement arc (with radius approximately 8 nozzle diameters) was already in the geometric far field for high-frequency sound (Strouhal number >5), low-frequency sound (Strouhal number <0.2) reached the geometric far field at a measurement radius of at least 50 nozzle diameters because of its extended source distribution.

Jet Fuel Exacerbated Noise-Induced Hearing Loss: Focus on Prediction of Central Auditory Processing Dysfunction

DTIC Science & Technology

2017-09-01

to develop a multi-scale model, together with relevant supporting experimental data, to describe jet fuel exacerbated noise induced hearing loss. In...scale model, together with relevant supporting experimental data, to describe jet fuel exacerbated noise-induced hearing loss. Such hearing loss...project was to develop a multi-scale model, together with relevant supporting experimental data, to describe jet fuel exacerbated NIHL. Herein we

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehtar-Tani, Yacine; Tywoniuk, Konrad

Here, we argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, thatmore » is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.« less

Groomed jets in heavy-ion collisions: sensitivity to medium-induced bremsstrahlung

DOE PAGES

Mehtar-Tani, Yacine; Tywoniuk, Konrad

2017-04-21

Here, we argue that contemporary jet substructure techniques might facilitate a more direct measurement of hard medium-induced gluon bremsstrahlung in heavy-ion collisions, and focus specifically on the “soft drop declustering” procedure that singles out the two leading jet substructures. Assuming coherent jet energy loss, we find an enhancement of the distribution of the energy fractions shared by the two substructures at small subjet energy caused by hard medium-induced gluon radiation. Departures from this approximation are discussed, in particular, the effects of colour decoherence and the contamination of the grooming procedure by soft background. Finally, we propose a complementary observable, thatmore » is the ratio of the two-pronged probability in Pb-Pb to proton-proton collisions and discuss its sensitivity to various energy loss mechanisms.« less

Nonquadratic gauge fixing and ghosts for gauge theories on the hypersphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, F. T.; McKeon, D. G. C.; Department of Mathematics and Computer Science, Algoma University, Sault St. Marie, Ontario P6A 2G4

2011-10-15

It has been suggested that using a gauge fixing Lagrangian that is not quadratic in a gauge fixing condition is most appropriate for gauge theories formulated on a hypersphere. We reexamine the appropriate ghost action that is to be associated with gauge fixing, applying a technique that has been used for ensuring that the propagator for a massless spin-two field is transverse and traceless. It is shown that this nonquadratic gauge fixing Lagrangian leads to two pair of complex Fermionic ghosts and two Bosonic real ghosts.

Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation

DOE PAGES

Byvank, T.; Banasek, J. T.; Potter, W. M.; ...

2017-12-07

We experimentally measure the effects of an applied axial magnetic field (B z) on laboratory plasma jets and compare experimental results with numerical simulations using an extended magnetohydrodynamics code. A 1 MA peak current, 100 ns rise time pulse power machine is used to generate the plasma jet. On application of the axial field, we observe on-axis density hollowing and a conical formation of the jet using interferometry, compression of the applied B z using magnetic B-dot probes, and azimuthal rotation of the jet using Thomson scattering. Experimentally, we find densities ≤ 5×10 17 cm -3 on-axis relative to jetmore » densities of ≥ 3×10 18 cm -3. For aluminum jets, 6.5 ± 0.5 mm above the foil, we find on-axis compression of the applied 1.0 ± 0.1 T B z to a total 2.4 ± 0.3 T, while simulations predict a peak compression to a total 3.4 T at the same location. On the aluminum jet boundary, we find ion azimuthal rotation velocities of 15-20 km/s, while simulations predict 14 km/s at the density peak. We discuss possible sources of discrepancy between the experiments and simulations, including: surface plasma on B-dot probes, optical fiber spatial resolution, simulation density floors, and 2D vs. 3D simulation effects. Lastly, this quantitative comparison between experiments and numerical simulations helps elucidate the underlying physics that determine the plasma dynamics of magnetized plasma jets.« less

Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byvank, T.; Banasek, J. T.; Potter, W. M.

We experimentally measure the effects of an applied axial magnetic field (B z) on laboratory plasma jets and compare experimental results with numerical simulations using an extended magnetohydrodynamics code. A 1 MA peak current, 100 ns rise time pulse power machine is used to generate the plasma jet. On application of the axial field, we observe on-axis density hollowing and a conical formation of the jet using interferometry, compression of the applied B z using magnetic B-dot probes, and azimuthal rotation of the jet using Thomson scattering. Experimentally, we find densities ≤ 5×10 17 cm -3 on-axis relative to jetmore » densities of ≥ 3×10 18 cm -3. For aluminum jets, 6.5 ± 0.5 mm above the foil, we find on-axis compression of the applied 1.0 ± 0.1 T B z to a total 2.4 ± 0.3 T, while simulations predict a peak compression to a total 3.4 T at the same location. On the aluminum jet boundary, we find ion azimuthal rotation velocities of 15-20 km/s, while simulations predict 14 km/s at the density peak. We discuss possible sources of discrepancy between the experiments and simulations, including: surface plasma on B-dot probes, optical fiber spatial resolution, simulation density floors, and 2D vs. 3D simulation effects. Lastly, this quantitative comparison between experiments and numerical simulations helps elucidate the underlying physics that determine the plasma dynamics of magnetized plasma jets.« less

A recipe for constructing frustration-free Hamiltonians with gauge and matter fields in one and two dimensions

NASA Astrophysics Data System (ADS)

Bernabé Ferreira, Miguel Jorge; Ibieta Jimenez, Juan Pablo; Padmanabhan, Pramod; Teôtonio Sobrinho, Paulo

2015-12-01

State sum constructions, such as Kuperberg’s algorithm, give partition functions of physical systems, like lattice gauge theories, in various dimensions by associating local tensors or weights with different parts of a closed triangulated manifold. Here we extend this construction by including matter fields to build partition functions in both two and three space-time dimensions. The matter fields introduce new weights to the vertices and they correspond to Potts spin configurations described by an {A}-module with an inner product. Performing this construction on a triangulated manifold with a boundary we obtain transfer matrices which are decomposed into a product of local operators acting on vertices, links and plaquettes. The vertex and plaquette operators are similar to the ones appearing in the quantum double models (QDMs) of Kitaev. The link operator couples the gauge and the matter fields, and it reduces to the usual interaction terms in known models such as {{{Z}}}2 gauge theory with matter fields. The transfer matrices lead to Hamiltonians that are frustration-free and are exactly solvable. According to the choice of the initial input, that of the gauge group and a matter module, we obtain interesting models which have a new kind of ground state degeneracy that depends on the number of equivalence classes in the matter module under gauge action. Some of the models have confined flux excitations in the bulk which become deconfined at the surface. These edge modes are protected by an energy gap provided by the link operator. These properties also appear in ‘confined Walker-Wang’ models which are 3D models having interesting surface states. Apart from the gauge excitations there are also excitations in the matter sector which are immobile and can be thought of as defects like in the Ising model. We only consider bosonic matter fields in this paper.

Laser Induced Fluorescence Detection of Gums in Jet Fuels

DTIC Science & Technology

1992-05-01

Classification) Laser Induced Fluorescence Detection of GLus in Jet Fuels 12 PERSONAL AUTHOR(S) David W. Naegeli and Ralph H. Hill 13a. TYPE OF REPORT 13b...degraded jet fuel.( ) 47 REFERENCES 1. Fodor, G.E.; Naegeli , D.W.; Kohl, K.B.; Cuellar, J.P., Jr., Interim Report BFLRF No. 199, AD A163590, Belvoir Fuels...and Lubricants Research Facility, Southwest Research Institute, San Antonio, TX, June 1985. 2. Fodor, G.E.; Naegeli , D.W., Proceedings of the 2nd

The near field of coaxial jets: A numerical study

NASA Astrophysics Data System (ADS)

Balarac, Guillaume; Métais, Olivier

2005-06-01

The near-field behavior of coaxial jets is studied through direct numerical simulation (DNS) with a particular focus on the influence of the inner shear layer steepness characterized by its momentum thickness θ01 thus mimicking the variation in the lip thickness of a real jet nozzle. We investigate the two distinct jet regimes ru>ruc for which a recirculation bubble is present near the jet inlet and rujet and inner jet velocities. It is shown that small values of θ01 lead to a fast transition to turbulence. The various mechanisms leading to this transition are investigated in detail: the three-dimensionality growth, the appearance of secondary vortices superimposed on the main ring vortices, and the subsequent longitudinal stretching of streamwise vortices. This stretching mechanism is shown to play a dominant role in the transition processes towards a fully developed turbulent state. For high enough values of ru, a pinching of the jet is observed near the inlet and it is shown that this pinching phenomenon lasts on a shorter downstream distance for small values of θ01 due to a more efficient turbulent mixing. In the ru>ruc case, variations of θ01 strongly affect the shape and the downstream extent of the recirculation bubble. The DNS allow to show the strong dependency of the inner and outer potential core lengths and of the critical value ruc on the jet inlet velocity profile. We finally revisit the theoretical model originally proposed by Rehab, Villermaux, and Hopfinger ["Flow regimes of large-velocity-ratio coaxial jets," J. Fluid Mech. 345, 357 (1997)] first aimed at the prediction of the variations of various jet characteristics as a function of ru. The model is extended to determine the dependency of the jet characteristics with θ01. A very good correspondence between the theoretical predictions and the numerical results is obtained.

Jet stability and wall impingement flow field in a thermal striping experiment

DOE PAGES

Lomperski, S.; Obabko, A.; Merzari, E.; ...

2017-08-10

We present velocity and temperature field measurements for a 0.9 x 0.9 x 1.7 m glass tank in which two air jets at Re=10000 mix and impinge upon the lid at ambient temperature and pressure. Flow patterns are characterized across a 350 x 200 mm plane located 3 mm below the lid for two inlet geometries: 1) “extended”, in which inlet channels protrude above the tank base, and 2) “flush”, a flat base without protrusions. This minor geometry variation produced distinct changes in the lid flow field, appearing as three stagnant regions for the extended case and only one formore » flush. The dichotomy is attributed to system stability characteristics: jets are stable in the extended case and unstable for flush. In a separate set of nonisothermal tests, the impingement temperature field was measured for inlet temperature mismatches of 4 oC and jets near Re=10000. A 50 m-long fiber optic distributed temperature sensor positioned 2 mm below the lid measured at 1350 locations. Like the velocity fields, the temperature fields differ for the two inlet geometries: good thermal mixing for the flush case and subdued mixing for the extended case. Simulations with the spectral element code Nek5000 replicated the observed stability dichotomy, duplicating the number of stagnant regions observed in the experiment and matching their locations within ±10 mm. Simulation data suggests that flush case instability is due to interactions between jets and wall flows at the bottom of the tank. The clear flow dichotomy exhibited by this two-jet setup presents an unambiguous case to test the ability of CFD tools to predict subtle flow field changes driven by minor modifications in geometry in the context of thermal striping.« less

Jet stability and wall impingement flow field in a thermal striping experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lomperski, S.; Obabko, A.; Merzari, E.

We present velocity and temperature field measurements for a 0.9 x 0.9 x 1.7 m glass tank in which two air jets at Re=10000 mix and impinge upon the lid at ambient temperature and pressure. Flow patterns are characterized across a 350 x 200 mm plane located 3 mm below the lid for two inlet geometries: 1) “extended”, in which inlet channels protrude above the tank base, and 2) “flush”, a flat base without protrusions. This minor geometry variation produced distinct changes in the lid flow field, appearing as three stagnant regions for the extended case and only one formore » flush. The dichotomy is attributed to system stability characteristics: jets are stable in the extended case and unstable for flush. In a separate set of nonisothermal tests, the impingement temperature field was measured for inlet temperature mismatches of 4 oC and jets near Re=10000. A 50 m-long fiber optic distributed temperature sensor positioned 2 mm below the lid measured at 1350 locations. Like the velocity fields, the temperature fields differ for the two inlet geometries: good thermal mixing for the flush case and subdued mixing for the extended case. Simulations with the spectral element code Nek5000 replicated the observed stability dichotomy, duplicating the number of stagnant regions observed in the experiment and matching their locations within ±10 mm. Simulation data suggests that flush case instability is due to interactions between jets and wall flows at the bottom of the tank. The clear flow dichotomy exhibited by this two-jet setup presents an unambiguous case to test the ability of CFD tools to predict subtle flow field changes driven by minor modifications in geometry in the context of thermal striping.« less

Gauge field propagator and the number of fermion fields

NASA Astrophysics Data System (ADS)

Oehme, Reinhard; Zimmermann, Wolfhart

1980-03-01

The structure of the transverse gluon propagator D of massless quantum chromodynamics is considered in the Landau gauge. The essential differences in the weak-coupling limit g-->0 for γ0β0>0 and γ0β0<0 are exhibited. Here γ0 and β0 are coefficients of lowest-order terms of the anomalous dimension and of the β function. For SU(3) as the color group and quark triplets, the corresponding flavor conditions are NF<=9 and 10<=NF<=16, respectively. It was shown previously that for γ˙0β0>0 there are inconsistencies with the postulates of local quantum field theory and the requirement that the positive-norm contribution D+ to D should approach its free-field value for g-->0. In the present paper, it is investigated in detail how this requirement is violated assuming that the other postulates hold, including invariance under the renormalization group. Using a specific, simple projection into a subspace of positive norm, it is shown that D+ diverges like (g2)-γ0β0, while the free-field value and higher-order terms of D are entirely due to contributions from negative-norm states. In contradistinction, the required dominance of positive-norm states in the weak-coupling limit prevails for γ0β0<0. In particular, the condition is fulfilled that D+ approaches its free-field value for g2-->0.

Gauge-invariant flow equation

NASA Astrophysics Data System (ADS)

Wetterich, C.

2018-06-01

We propose a closed gauge-invariant functional flow equation for Yang-Mills theories and quantum gravity that only involves one macroscopic gauge field or metric. It is based on a projection on physical and gauge fluctuations. Deriving this equation from a functional integral we employ the freedom in the precise choice of the macroscopic field and the effective average action in order to realize a closed and simple form of the flow equation.

Miniature Convection Cooled Plug-type Heat Flux Gauges

NASA Technical Reports Server (NTRS)

Liebert, Curt H.

1994-01-01

Tests and analysis of a new miniature plug-type heat flux gauge configuration are described. This gauge can simultaneously measure heat flux on two opposed active surfaces when heat flux levels are equal to or greater than about 0.2 MW/m(sup 2). The performance of this dual active surface gauge was investigated over a wide transient and steady heat flux and temperature range. The tests were performed by radiatively heating the front surface with an argon arc lamp while the back surface was convection cooled with air. Accuracy is about +20 percent. The gauge is responsive to fast heat flux transients and is designed to withstand the high temperature (1300 K), high pressure (15 MPa), erosive and corrosive environments in modern engines. This gauge can be used to measure heat flux on the surfaces of internally cooled apparatus such as turbine blades and combustors used in jet propulsion systems and on the surfaces of hypersonic vehicles. Heat flux measurement accuracy is not compromised when design considerations call for various size gauges to be fabricated into alloys of various shapes and properties. Significant gauge temperature reductions (120 K), which can lead to potential gauge durability improvement, were obtained when the gauges were air-cooled by forced convection.

Jet fuel-induced immunotoxicity.

PubMed

Harris, D T; Sakiestewa, D; Titone, D; Robledo, R F; Young, R S; Witten, M

2000-09-01

Chronic exposure to jet fuel has been shown to cause human liver dysfunction, emotional dysfunction, abnormal electroencephalograms, shortened attention spans, and to decrease sensorimotor speed (3-5). Exposure to potential environmental toxicants such as jet fuel may have significant effects on host systems beyond those readily visible (e.g., physiology, cardiology, respiratory, etc.), e.g., the immune system. Significant changes in immune function, even if short-lived, may have serious consequences for the exposed host that may impinge affect susceptibility to infectious agents. Major alterations in immune function that are long lasting may result in an increased likelihood of development and/or progression of cancer, as well as autoimmune diseases. In the current study mice were exposed 1 h/day for 7 days to a 1000-mg/m3 concentration of aerosolized jet fuel obtained from various sources (JP-8, JP-8+100 and Jet A1) and of differing compositions to simulate occupational exposures. Twenty-four hours after the last exposure the mice were analyzed for effects on the immune system. It was observed that exposure to all jet fuel sources examined had detrimental effects on the immune system. Decreases in viable immune cell numbers and immune organ weights were found. Jet fuel exposure resulted in differential losses of immune cell populations in the thymus. Further, jet fuel exposure resulted in significantly decreased immune function, as analyzed by mitogenesis assays. Suppressed immune function could not be overcome by the addition of exogenous growth factors known to stimulate immune function. Thus, short-term, low-concentration exposure of mice to aerosolized jet fuel, regardless of source or composition, caused significant deleterious effects on the immune system.

Torsion in gauge theory

NASA Astrophysics Data System (ADS)

Nieh, H. T.

2018-02-01

The potential conflict between torsion and gauge symmetry in the Riemann-Cartan curved spacetime was noted by Kibble in his 1961 pioneering paper and has since been discussed by many authors. Kibble suggested that, to preserve gauge symmetry, one should forgo the covariant derivative in favor of the ordinary derivative in the definition of the field strength Fμ ν for massless gauge theories, while for massive vector fields, covariant derivatives should be adopted. This view was further emphasized by Hehl et al. in their influential 1976 review paper. We address the question of whether this deviation from normal procedure by forgoing covariant derivatives in curved spacetime with torsion could give rise to inconsistencies in the theory, such as the quantum renormalizability of a realistic interacting theory. We demonstrate in this paper the one-loop renormalizability of a realistic gauge theory of gauge bosons interacting with Dirac spinors, such as the SU(3) chromodynamics, for the case of a curved Riemann-Cartan spacetime with totally antisymmetric torsion. This affirmative confirmation is one step toward providing justification for the assertion that the flat-space definition of the gauge-field strength should be adopted as the proper definition.

Black holes with su(N) gauge field hair and superconducting horizons

NASA Astrophysics Data System (ADS)

Shepherd, Ben L.; Winstanley, Elizabeth

2017-01-01

We present new planar dyonic black hole solutions of the su(N) Einstein-Yang-Mills equations in asymptotically anti-de Sitter space-time, focussing on su(2) and su(3) gauge groups. The magnetic part of the gauge field forms a condensate close to the planar event horizon. We compare the free energy of a non-Abelian hairy black hole with that of an embedded Reissner-Nordström-anti-de Sitter (RN-AdS) black hole having the same Hawking temperature and electric charge. We find that the hairy black holes have lower free energy. We present evidence that there is a phase transition at a critical temperature, above which the only solutions are embedded RN-AdS black holes. At the critical temperature, an RN-AdS black hole can decay into a hairy black hole, and it is thermodynamically favourable to do so. Working in the probe limit, we compute the frequency-dependent conductivity, and find that enlarging the gauge group from su(2) to su(3) eliminates a divergence in the conductivity at nonzero frequency.

Plane boundary effects on characteristics of propeller jets

NASA Astrophysics Data System (ADS)

Wei, Maoxing; Chiew, Yee-Meng; Hsieh, Shih-Chun

2017-10-01

The flow properties of a propeller jet in the presence of a plane bed boundary were investigated using the particle image velocimetry technique. Three clearance heights, Z b = 2 D p, D p, and 0.5 D p, where D p = propeller diameter, were used to examine boundary effects on the development of the jet. In each case, the mean flow properties and turbulence characteristics were measured in a larger field of view than those used in past studies. Both the streamwise and transverse flow fields were measured to obtain the three-dimensional characteristics of the propeller jet. Similar to a confined offset jet, the propeller jet also exhibits a wall attachment behavior when it is placed near a plane boundary. As a result, in contrast to its unconfined counterpart, the confined propeller jet features three regions, namely the free jet, impingement and wall jet regions. The study shows that the extent of each region varies under different clearance heights. The development of the mean flow and turbulence characteristics associated with varying clearance heights are compared to illustrate boundary effects in these regions. In the impingement region, the measured transverse flow fields provide new insights on the lateral motions induced by the impingement of the swirling jet. In the wall jet region, observations reveal that the jet behaves like a typical three-dimensional wall jet and its axial velocity profiles show good agreement with the classical wall jet similarity function.

Fine-scale features in the far-field of a turbulent jet

NASA Astrophysics Data System (ADS)

Buxton, Oliver; Ganapathisubramani, Bharathram

2008-11-01

The structure of a fully turbulent axisymmetric jet, at Reynolds number based on jet exit conditions of 5000, is investigated with cinematographic (1 kHz) stereoscopic PIV in a plane normal to the jet axis. Taylor's hypothesis is employed to calculate all three velocity gradients in the axial direction. The technique's resolution allows all terms of the velocity gradient tensor, hence strain rate tensor and kinetic energy dissipation, to be computed at each point within the plane. The data reveals that the vorticity field is dominated by high enstrophy tube-like structures. Conversely, the dissipation field appears to consist of sheet-like structures. Several criteria for isolating these strongly swirling vortical structures from the background turbulence were employed. One such technique involves isolating points in which the velocity gradient tensor has a real and a pair of complex conjugate eigenvectors. Once identified, the alignment of the various structures with relation to the vorticity vector and the real velocity gradient tensor eigenvector is investigated. The effect of the strain field on the geometry of the structures is also examined.

3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

2006-01-01

Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

Torque Enhancement, Spin Equilibrium, and Jet Power from Disk-Induced Opening of Pulsar Magnetic Fields

NASA Astrophysics Data System (ADS)

Parfrey, Kyle; Spitkovsky, Anatoly; Beloborodov, Andrei M.

2016-05-01

The interaction of a rotating star’s magnetic field with a surrounding plasma disk lies at the heart of many questions posed by neutron stars in X-ray binaries. We consider the opening of stellar magnetic flux due to differential rotation along field lines coupling the star and disk, using a simple model for the disk-opened flux, the torques exerted on the star by the magnetosphere, and the power extracted by the electromagnetic wind. We examine the conditions under which the system enters an equilibrium spin state, in which the accretion torque is instantaneously balanced by the pulsar wind torque alone. For magnetic moments, spin frequencies, and accretion rates relevant to accreting millisecond pulsars, the spin-down torque from this enhanced pulsar wind can be substantially larger than that predicted by existing models of the disk-magnetosphere interaction, and is in principle capable of maintaining spin equilibrium at frequencies less than 1 kHz. We speculate that this mechanism may account for the non-detection of frequency increases during outbursts of SAX J1808.4-3658 and XTE J1814-338, and may be generally responsible for preventing spin-up to sub-millisecond periods. If the pulsar wind is collimated by the surrounding environment, the resulting jet can satisfy the power requirements of the highly relativistic outflows from Cir X-1 and Sco X-1. In this framework, the jet power scales relatively weakly with accretion rate, {L}{{j}}\\propto {\\dot{M}}4/7, and would be suppressed at high accretion rates only if the stellar magnetic moment is sufficiently low.

Nambu-Poisson gauge theory

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Schupp, Peter; Vysoký, Jan

2014-06-01

We generalize noncommutative gauge theory using Nambu-Poisson structures to obtain a new type of gauge theory with higher brackets and gauge fields. The approach is based on covariant coordinates and higher versions of the Seiberg-Witten map. We construct a covariant Nambu-Poisson gauge theory action, give its first order expansion in the Nambu-Poisson tensor and relate it to a Nambu-Poisson matrix model.

Magnetic jets from accretion disks : field structure and X-ray emission

NASA Astrophysics Data System (ADS)

Memola, Elisabetta

2002-06-01

Jets are highly collimated flows of matter. They are present in a large variety of astrophysical sources: young stars, stellar mass black holes (microquasars), galaxies with an active nucleus (AGN) and presumably also intense flashes of gamma-rays. In particular, the jets of microquasars, powered by accretion disks, are probably small-scale versions of the outflows from AGN. Beside observations of astrophysical jet sources, also theoretical considerations have shown that magnetic fields play an important role in jet formation, acceleration and collimation. Collimated jets seem to be systematically associated with the presence of an accretion disk around a star or a collapsed object. If the central object is a black hole, the surrounding accretion disk is the only possible location for a magnetic field generation. We are interested in the formation process of highly relativistic jets as observed from microquasars and AGN. We theoretically investigate the jet collimation region, whose physical dimensions are extremely tiny even compared to radio telescopes spatial resolution. Thus, for most of the jet sources, global theoretical models are, at the moment, the only possibility to gain information about the physical processes in the innermost jet region. For the first time, we determine the global two-dimensional field structure of stationary, axisymmetric, relativistic, strongly magnetized (force-free) jets collimating into an asymptotically cylindrical jet (taken as boundary condition) and anchored into a differentially rotating accretion disk. This approach allows for a direct connection between the accretion disk and the asymptotic collimated jet. Therefore, assuming that the foot points of the field lines are rotating with Keplerian speed, we are able to achieve a direct scaling of the jet magnetosphere in terms of the size of the central object. We find a close compatibility between the results of our model and radio observations of the M87 galaxy innermost jet

Noncommutative gauge theories and Kontsevich's formality theorem

NASA Astrophysics Data System (ADS)

Jurčo, B.; Schupp, P.; Wess, J.

2001-09-01

The equivalence of star products that arise from the background field with and without fluctuations and Kontsevich's formality theorem allow an explicitly construction of a map that relates ordinary gauge theory and noncommutative gauge theory (Seiberg-Witten map.) Using noncommutative extra dimensions the construction is extended to noncommutative nonabelian gauge theory for arbitrary gauge groups; as a byproduct we obtain a "Mini Seiberg-Witten map" that explicitly relates ordinary abelian and nonabelian gauge fields. All constructions are also valid for non-constant B-field, and even more generally for any Poisson tensor.

A study of the round jet/plane wall flow field

NASA Technical Reports Server (NTRS)

Foss, J. F.; Kleis, S. J.

1971-01-01

Impingement angles, between the axisymmetric jet axis and the plane wall, from zero to 15 degrees have been examined for nozzle heights of 0.75, 1.0, 1.5 and 2.0 diameters and for: (1) a fully developed pipe flow, and (2) a relatively uniform exit velocity condition. Velocity measurements have been used to define isotach contours and to determine mass, momentum and energy flux values for the near field (within five diameters) of the jet. Surface pressure measurements have been used to define surface pressure forces and jet centerline trajectories. The geometric and flow conditions examined and the interpretation of the results have been motivated by the externally blown flap STOL aircraft application.

Chiral Anomaly from Strain-Induced Gauge Fields in Dirac and Weyl Semimetals

NASA Astrophysics Data System (ADS)

Pikulin, D. I.; Chen, Anffany; Franz, M.

2016-10-01

Dirac and Weyl semimetals form an ideal platform for testing ideas developed in high-energy physics to describe massless relativistic particles. One such quintessentially field-theoretic idea of the chiral anomaly already resulted in the prediction and subsequent observation of the pronounced negative magnetoresistance in these novel materials for parallel electric and magnetic fields. Here, we predict that the chiral anomaly occurs—and has experimentally observable consequences—when real electromagnetic fields E and B are replaced by strain-induced pseudo-electromagnetic fields e and b . For example, a uniform pseudomagnetic field b is generated when a Weyl semimetal nanowire is put under torsion. In accordance with the chiral anomaly equation, we predict a negative contribution to the wire resistance proportional to the square of the torsion strength. Remarkably, left- and right-moving chiral modes are then spatially segregated to the bulk and surface of the wire forming a "topological coaxial cable." This produces hydrodynamic flow with potentially very long relaxation time. Another effect we predict is the ultrasonic attenuation and electromagnetic emission due to a time-periodic mechanical deformation causing pseudoelectric field e . These novel manifestations of the chiral anomaly are most striking in the semimetals with a single pair of Weyl nodes but also occur in Dirac semimetals such as Cd3 As2 and Na3Bi and Weyl semimetals with unbroken time-reversal symmetry.

Electric field measurement in the dielectric tube of helium atmospheric pressure plasma jet

NASA Astrophysics Data System (ADS)

Sretenović, Goran B.; Guaitella, Olivier; Sobota, Ana; Krstić, Ivan B.; Kovačević, Vesna V.; Obradović, Bratislav M.; Kuraica, Milorad M.

2017-03-01

The results of the electric field measurements in the capillary of the helium plasma jet are presented in this article. Distributions of the electric field for the streamers are determined for different gas flow rates. It is found that electric field strength in front of the ionization wave decreases as it approaches to the exit of the tube. The values obtained under presented experimental conditions are in the range of 5-11 kV/cm. It was found that the increase in gas flow above 1500 SCCM could induce substantial changes in the discharge operation. This is reflected through the formation of the brighter discharge region and appearance of the electric field maxima. Furthermore, using the measured values of the electric field strength in the streamer head, it was possible to estimate electron densities in the streamer channel. Maximal density of 4 × 1011 cm-3 is obtained in the vicinity of the grounded ring electrode. Similar behaviors of the electron density distributions to the distributions of the electric field strength are found under the studied experimental conditions.

Remarks on the BRST quantized gauged WZNW models and the Toda field theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, N.

In this paper it is shown that the quantum Hamiltonian reduction proposed by Bershadsky and Ooguri enables us to connect the gauged WZNW models with fractional levels to the quantum Toda field theories, and the coupling constants of the Toda field theories with the fractional levels. The BRST framework is applied to the SL ({ital n},R)-WZNW models.

3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.

2006-01-01

Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

An Analysis of the Pressures, Forces and Moments Induced by the Ground Vortex Generated by a Single Impinging Jet

NASA Technical Reports Server (NTRS)

Kuhn, Richard E.

1997-01-01

When a jet STOVL aircraft is in STOL operation the jets impinge on the ground and generate wall jets flowing radially outward from the points at which the jets impinge. When the forward flowing part of a wall jet meets the free stream flow it is rolled back on itself forming a parabolic shaped ground vortex. Positive pressures are induced on the lower surface of the configuration ahead of the ground vortex and suction pressures are induced over the ground vortex itself. In addition, the suction pressures induced aft of the jet out of ground effect are reduced and lifting pressures are induced on the upper surface. This study analyzes available pressure and force data and develops a method for estimating the forces and moments induced in ground effect. The method includes the effects of configuration variables, height and operating conditions, as well as the effects of the location, deflection and shape of the jet. However, it is limited to single jets at subcritical nozzle pressure ratios. An analysis of the effects of moving over the ground vs. tests over a fixed ground plane is included.

A Three-dimensional Magnetohydrodynamic Simulation of the Formation of Solar Chromospheric Jets with Twisted Magnetic Field Lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iijima, H.; Yokoyama, T., E-mail: h.iijima@isee.nagoya-u.ac.jp

This paper presents a three-dimensional simulation of chromospheric jets with twisted magnetic field lines. Detailed treatments of the photospheric radiative transfer and the equations of state allow us to model realistic thermal convection near the solar surface, which excites various MHD waves and produces chromospheric jets in the simulation. A tall chromospheric jet with a maximum height of 10–11 Mm and lifetime of 8–10 minutes is formed above a strong magnetic field concentration. The magnetic field lines are strongly entangled in the chromosphere, which helps the chromospheric jet to be driven by the Lorentz force. The jet exhibits oscillatory motionmore » as a natural consequence of its generation mechanism. We also find that the produced chromospheric jet forms a cluster with a diameter of several Mm with finer strands. These results imply a close relationship between the simulated jet and solar spicules.« less

Pulsed laser-induced liquid jet: evolution from shock/bubble interaction to neurosurgical application

NASA Astrophysics Data System (ADS)

Nakagawa, A.; Kumabe, T.; Ogawa, Y.; Hirano, T.; Kawaguchi, T.; Ohtani, K.; Nakano, T.; Sato, C.; Yamada, M.; Washio, T.; Arafune, T.; Teppei, T.; Atsushi, K.; Satomi, S.; Takayama, K.; Tominaga, T.

2017-01-01

The high-speed liquid (water) jet has distinctive characteristics in surgical applications, such as tissue dissection without thermal damage and small blood vessel preservation, that make it advantageous over more conventional instruments. The continuous pressurized jet has been used since the first medical application of water jets to liver surgery in the 1980s, but exhibited drawbacks partly related to the excess water supply required and unsuitability for application to microsurgical instruments intended for deep, narrow lesions (endoscopic instrumentation and catheters) due to limitations in miniaturization of the device. To solve these issues, we initiated work on the pulsed micro-liquid jet. The idea of the pulsed micro-liquid jet originated from the observation of tissue damage by shock/bubble interactions during extracorporeal shock wave lithotripsy and evolved into experimental application for recanalization of cerebral embolisms in the 1990s. The original method of generating the liquid jet was based on air bubble formation and microexplosives as the shock wave source, and as such could not be applied clinically. The air bubble was replaced by a holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced bubble. Finally, the system was simplified and the liquid jet was generated via irradiation from the Ho:YAG laser within a liquid-filled tubular structure. A series of investigations revealed that this pulsed laser-induced liquid jet (LILJ) system has equivalent dissection and blood vessel preservation characteristics, but the amount of liquid usage has been reduced to less than 2 μ l per shot and can easily be incorporated into microsurgical, endoscopic, and catheter devices. As a first step in human clinical studies, we have applied the LILJ system for the treatment of skull base tumors through the transsphenoidal approach in 9 patients (7 pituitary adenomas and 2 chordomas), supratentorial glioma (all high grade glioma) in 8 patients, including one with

Air-jet power ultrasonic field applied to electrical discharge

NASA Astrophysics Data System (ADS)

Balek, Rudolf; Pekarek, Stanislav

2010-01-01

We describe a new setup of the Hartmann air-jet ultrasonic generator combined with electrical discharge in the nozzle-resonator gap. Using the schlieren visualization of air jet and ultrasonic field we investigated the shape and structure of the discharge and we determined relationship among the acoustic field in the nozzle-resonator gap, generator ultrasonic emission and discharge behavior. Apart of the fact that the discharge in the nozzle-resonator gap is stabilized and becomes more uniform, it increases its volume when the generator works in the regime of ultrasonic emission. At the same time the discharge light emission distribution is more over uniform in the gap. In the regime without the ultrasonic emission the discharge light emission is fragmented. We also found that the impedance of the discharge is decreased in case when the generator works in the regime of ultrasonic emission.

Nonabelian noncommutative gauge theory via noncommutative extra dimensions

NASA Astrophysics Data System (ADS)

Jurčo, Branislav; Schupp, Peter; Wess, Julius

2001-06-01

The concept of covariant coordinates on noncommutative spaces leads directly to gauge theories with generalized noncommutative gauge fields of the type that arises in string theory with background B-fields. The theory is naturally expressed in terms of cochains in an appropriate cohomology; we discuss how it fits into the framework of projective modules. The equivalence of star products that arise from the background field with and without fluctuations and Kontsevich's formality theorem allow an explicitly construction of a map that relates ordinary gauge theory and noncommutative gauge theory (Seiberg-Witten map). As application we show the exact equality of the Dirac-Born-Infeld action with B-field in the commutative setting and its semi-noncommutative cousin in the intermediate picture. Using noncommutative extra dimensions the construction is extended to noncommutative nonabelian gauge theory for arbitrary gauge groups; an explicit map between abelian and nonabelian gauge fields is given. All constructions are also valid for non-constant B-field, Poisson structure and metric.

Topological Quantum Phase Transition in Synthetic Non-Abelian Gauge Potential: Gauge Invariance and Experimental Detections

PubMed Central

Sun, Fadi; Yu, Xiao-Lu; Ye, Jinwu; Fan, Heng; Liu, Wu-Ming

2013-01-01

The method of synthetic gauge potentials opens up a new avenue for our understanding and discovering novel quantum states of matter. We investigate the topological quantum phase transition of Fermi gases trapped in a honeycomb lattice in the presence of a synthetic non-Abelian gauge potential. We develop a systematic fermionic effective field theory to describe a topological quantum phase transition tuned by the non-Abelian gauge potential and explore its various important experimental consequences. Numerical calculations on lattice scales are performed to compare with the results achieved by the fermionic effective field theory. Several possible experimental detection methods of topological quantum phase transition are proposed. In contrast to condensed matter experiments where only gauge invariant quantities can be measured, both gauge invariant and non-gauge invariant quantities can be measured by experimentally generating various non-Abelian gauges corresponding to the same set of Wilson loops. PMID:23846153

Three dimensional flow field measurements of a 4:1 aspect ratio subsonic jet

NASA Technical Reports Server (NTRS)

Morrison, G. L.; Swan, D. H.

1989-01-01

Flow field measurements for a subsonic rectangular cold air jet with an aspect ratio of 4:1 (12.7 x 50.8 mm) at a Mach number of 0.09 and Re of 100,000 have been carried out using a three-dimensional laser Doppler anemometer system. Mean velocity measurements show that the jet width spreads more rapidly along the minor axis than along the major axis. The outward velocities, however, are not significantly different for the two axes, indicating the presence of enhanced mixing along the minor axis. The jet slowly changes from a rectangular jet to a circular jet as the flow progresses downstream.

Anomaly-Induced Dynamical Refringence in Strong-Field QED

NASA Astrophysics Data System (ADS)

Mueller, N.; Hebenstreit, F.; Berges, J.

2016-08-01

We investigate the impact of the Adler-Bell-Jackiw anomaly on the nonequilibrium evolution of strong-field quantum electrodynamics (QED) using real-time lattice gauge theory techniques. For field strengths exceeding the Schwinger limit for pair production, we encounter a highly absorptive medium with anomaly induced dynamical refractive properties. In contrast to earlier expectations based on equilibrium properties, where net anomalous effects vanish because of the trivial vacuum structure, we find that out-of-equilibrium conditions can have dramatic consequences for the presence of quantum currents with distinctive macroscopic signatures. We observe an intriguing tracking behavior, where the system spends longest times near collinear field configurations with maximum anomalous current. Apart from the potential relevance of our findings for future laser experiments, similar phenomena related to the chiral magnetic effect are expected to play an important role for strong QED fields during initial stages of heavy-ion collision experiments.

Bianchi cosmologies with p-form gauge fields

NASA Astrophysics Data System (ADS)

Normann, Ben David; Hervik, Sigbjørn; Ricciardone, Angelo; Thorsrud, Mikjel

2018-05-01

In this paper the dynamics of free gauge fields in Bianchi type I–VII h space-times is investigated. The general equations for a matter sector consisting of a p-form field strength (p \\in \\{1, 3\\} ), a cosmological constant (4-form) and perfect fluid in Bianchi type I–VII h space-times are computed using the orthonormal frame method. The number of independent components of a p-form in all Bianchi types I–IX are derived and, by means of the dynamical systems approach, the behaviour of such fields in Bianchi type I and V are studied. Both a local and a global analysis are performed and strong global results regarding the general behaviour are obtained. New self-similar cosmological solutions appear both in Bianchi type I and Bianchi type V, in particular, a one-parameter family of self-similar solutions, ‘Wonderland (λ)’ appears generally in type V and in type I for λ=0 . Depending on the value of the equation of state parameter other new stable solutions are also found (‘The Rope’ and ‘The Edge’) containing a purely spatial field strength that rotates relative to the co-moving inertial tetrad. Using monotone functions, global results are given and the conditions under which exact solutions are (global) attractors are found.

Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by theirmore » passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving “downward” into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we

Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

DOE PAGES

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey; ...

2018-02-02

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by theirmore » passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving “downward” into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we

Evolution of the mean jet shape and dijet asymmetry distribution of an ensemble of holographic jets in strongly coupled plasma

NASA Astrophysics Data System (ADS)

Brewer, Jasmine; Rajagopal, Krishna; Sadofyev, Andrey; van der Schee, Wilke

2018-02-01

Some of the most important experimentally accessible probes of the quark- gluon plasma (QGP) produced in heavy ion collisions come from the analysis of how the shape and energy of sprays of energetic particles produced within a cone with a specified opening angle (jets) in a hard scattering are modified by their passage through the strongly coupled, liquid, QGP. We model an ensemble of back-to-back dijets for the purpose of gaining a qualitative understanding of how the shapes of the individual jets and the asymmetry in the energy of the pairs of jets in the ensemble are modified by their passage through an expanding cooling droplet of strongly coupled plasma, in the model in a holographic gauge theory that is dual to a 4+1-dimensional black-hole spacetime that is asymptotically anti-de Sitter (AdS). We build our model by constructing an ensemble of strings in the dual gravitational description of the gauge theory. We model QCD jets in vacuum using strings whose endpoints are moving "downward" into the gravitational bulk spacetime with some fixed small angle, an angle that represents the opening angle (ratio of jet mass to jet energy) that the QCD jet would have in vacuum. Such strings must be moving through the gravitational bulk at (close to) the speed of light; they must be (close to) null. This condition does not specify the energy distribution along the string, meaning that it does not specify the shape of the jet being modeled. We study the dynamics of strings that are initially not null and show that strings with a wide range of initial conditions rapidly accelerate and become null and, as they do, develop a similar distribution of their energy density. We use this distribution of the energy density along the string, choose an ensemble of strings whose opening angles and energies are distributed as in perturbative QCD, and show that we can then fix one of the two model parameters such that the mean jet shape for the jets in the ensemble that we have built

Vapor condensation on liquid surface due to laminar jet-induced mixing: The effects of system parameters

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun; Hasan, Mohammad M.

1989-01-01

The effects of system parameters on the interface condensation rate in a laminar jet induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a slightly subcooled jet discharged from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The jet velocity is selected to be low enough such that the free surface is approximately flat. The effect of vapor superheat is assumed to be negligible. Therefore, the interface condensation rate can be determined from the resulting temperature field in the liquid region alone. The nondimensional form of the steady state conservation equations are solved by a finite difference method for various system parameters including liquid height to tank diameter ratio, tank to jet diameter ratio, liquid inflow to outflow area ratio, and a heat leak parameter which characterizes the uniform wall heat flux. Detailed analyses based on the numerical solutions are performed and simplified equations are suggested for the prediction of condensation rate.

Gauged U(1) clockwork theory

NASA Astrophysics Data System (ADS)

Lee, Hyun Min

2018-03-01

We consider the gauged U (1) clockwork theory with a product of multiple gauge groups and discuss the continuum limit of the theory to a massless gauged U (1) with linear dilaton background in five dimensions. The localization of the lightest state of gauge fields on a site in the theory space naturally leads to exponentially small effective couplings of external matter fields localized away from the site. We discuss the implications of our general discussion with some examples, such as mediators of dark matter interactions, flavor-changing B-meson decays as well as D-term SUSY breaking.

Gauged Q-balls

NASA Technical Reports Server (NTRS)

Lee, Kimyeong; Stein-Schabes, Jaime A.; Watkins, Richard; Widrow, Lawrence M.

1988-01-01

Classical non-topological soliton configurations are considered within the theory of a complex scalar field with a gauged U symmetry. Their existence and stability against dispersion are demonstrated and some of their properties are investigated analytically and numerically. The soliton configuration is such that inside the soliton the local U symmetry is broken, the gauge field becomes massive and for a range of values of the coupling constants the soliton becomes a superconductor pushing the charge to the surface. Furthermore, because of the repulsive Coulomb force, there is a maximum size for these objects, making impossible the existence of Q-matter in bulk form. Also briefly discussed are solitons with fermions in a U gauge theory.

Multiloop amplitudes of light-cone gauge superstring field theory: odd spin structure contributions

NASA Astrophysics Data System (ADS)

Ishibashi, Nobuyuki; Murakami, Koichi

2018-03-01

We study the odd spin structure contributions to the multiloop amplitudes of light-cone gauge superstring field theory. We show that they coincide with the amplitudes in the conformal gauge with two of the vertex operators chosen to be in the pictures different from the standard choice, namely (-1, -1) picture in the type II case and -1 picture in the heterotic case. We also show that the contact term divergences can be regularized in the same way as in the amplitudes for the even structures and we get the amplitudes which coincide with those obtained from the first-quantized approach.

Holmium: YAG laser-induced liquid jet knife: possible novel method for dissection.

PubMed

Nakagawa, Atsuhiro; Hirano, Takayuki; Komatsu, Makoto; Sato, Mariko; Uenohara, Hiroshi; Ohyama, Hideki; Kusaka, Yasuko; Shirane, Reizo; Takayama, Kazuyoshi; Yoshimoto, Takashi

2002-01-01

Making surgical incisions in vessel-rich organs without causing bleeding is difficult. Thus, it is necessary to develop new devices for this purpose, especially for surgery involving small vessels as in neurosurgery, where damage against even small cerebral vessels result in severe neurological deficits. A laser-induced liquid jet was generated by irradiating pulsed Holmium Yttrium-Aluminum-Garnet (Ho: YAG) laser (beams of 350 microseconds pulse width) within a copper tube (internal diameter, 1 mm) with pure water (150 ml /hour). Ho: YAG laser beams were irradiated through an optical fiber (core diameter, 0.4 mm). The influence of the input of laser energy, structure of the nozzle, and the stand-off distance between the optical fiber tip and nozzle exit on the jet velocity was measured by a high-speed video camera to evaluate controllability of jet. The effect on artificial organs made of 10 and 30%(w/v) gelatin, each of which represent features of soft tissue and blood vessels. Jet velocity increased in proportion to gain in laser energy input, and maximum penetration depth into 10%(w/v) gelatin was 35 mm by single exposure at 350 mJ/pulse without impairing a vessel model. Shapes of nozzle also modified jet velocity with optimal nozzle/tube area ratio of 0.25. The laser-induced liquid jet has excellent potential as a new tool for removing soft tissue without damaging vital structures. Copyright 2002 Wiley-Liss, Inc.

Velocity field near the jet orifice of a round jet in a crossflow

NASA Technical Reports Server (NTRS)

Fearn, R. L.; Benson, J. P.

1979-01-01

Experimentally determined velocities at selected locations near the jet orifice are presented and analyzed for a round jet in crossflow. Jet-to-crossflow velocity ratios of four and eight were studied experimentally for a round subsonic jet of air exhausting perpendicularly through a flat plate into a subsonic crosswind of the same temperature. Velocity measurements were made in cross sections to the jet plume located from one to four jet diameters from the orifice. Jet centerline and vortex properties are presented and utilized to extend the results of a previous study into the region close to the jet orifice.

Improved field emission properties of carbon nanotubes grown on stainless steel substrate and its application in ionization gauge

NASA Astrophysics Data System (ADS)

Li, Detian; Cheng, Yongjun; Wang, Yongjun; Zhang, Huzhong; Dong, Changkun; Li, Da

2016-03-01

Vertically aligned carbon nanotube (CNT) arrays were fabricated by chemical vapor deposition (CVD) technique on different substrates. Microstructures and field emission characteristics of the as-grown CNT arrays were investigated systematically, and its application in ionization gauge was also evaluated preliminarily. The results indicate that the as-grown CNT arrays are vertically well-aligned relating to the substrate surfaces, but the CNTs grown on stainless steel substrate are longer and more crystalline than the ones grown on silicon wafer substrate. The field emission behaviors of the as-grown CNT arrays are strongly dependent upon substrate properties. Namely, the CNT array grown on stainless steel substrate has better field emission properties, including lower turn on and threshold fields, better emission stability and repeatability, compared with the one grown on silicon wafer substrate. The superior field emission properties of the CNT array grown on stainless steel substrate are mainly attributed to low contact resistance, high thermal conductivity, good adhesion strength, etc. In addition, the metrological behaviors of ionization gauge with the CNT array grown on stainless steel substrate as an electron source were investigated, and this novel cathode ionization gauge extends the lower limit of linear pressure measurement to 10-8 Pa, which is one order of magnitude lower than the result reported for the same of gauge with CNT cathode.

An A{sub r} threesome: Matrix models, 2d conformal field theories, and 4dN=2 gauge theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiappa, Ricardo; Wyllard, Niclas

We explore the connections between three classes of theories: A{sub r} quiver matrix models, d=2 conformal A{sub r} Toda field theories, and d=4N=2 supersymmetric conformal A{sub r} quiver gauge theories. In particular, we analyze the quiver matrix models recently introduced by Dijkgraaf and Vafa (unpublished) and make detailed comparisons with the corresponding quantities in the Toda field theories and the N=2 quiver gauge theories. We also make a speculative proposal for how the matrix models should be modified in order for them to reproduce the instanton partition functions in quiver gauge theories in five dimensions.

Coronal Jets in Closed Magnetic Regions on the Sun

NASA Astrophysics Data System (ADS)

Wyper, Peter Fraser; DeVore, C. R.

2015-04-01

Coronal jets are dynamic, collimated structures observed in solar EUV and X-ray emission. They appear predominantly in the open field of coronal holes, but are also observed in areas of closed field, especially active regions. A common feature of coronal jets is that they originate from the field above a parasitic polarity of opposite sign to the surrounding field. Some process - such as instability onset or flux emergence - induces explosive reconnection between the closed “anemone” field and the surrounding open field that generates the jet. The lesser number of coronal jets in closed-field regions suggests a possible stabilizing effect of the closed configuration with respect to coronal jet formation. If the scale of the jet region is small compared with the background loop length, as in for example type II spicules, the nearby magnetic field may be treated as locally open. As such, one would expect that if a stabilizing effect exists it becomes most apparent as the scale of the anemone region approaches that of the background coronal loops.To investigate if coronal jets are indeed suppressed along shorter coronal loops, we performed a number of simulations of jets driven by a rotation of the parasitic polarity (as in the previous open-jet calculations by Pariat et. al 2009, 2010, 2015) embedded in a large-scale closed bipolar field. The simulations were performed with the state of the art Adaptively Refined Magnetohydrodynamics Solver. We will report here how the magnetic configuration above the anemone region determines the nature of the jet, when it is triggered, and how much of the stored magnetic energy is released. We show that regions in which the background field and the parasitic polarity region are of comparable scale naturally suppress explosive energy release. We will also show how in the post-jet relaxation phase a combination of confined MHD waves and weak current layers are generated by the jet along the background coronal loops, both of which

Restoration of the covariant gauge α in the initial field of gravity in de Sitter spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheong, Lee Yen; Yan, Chew Xiao

2014-03-05

The gravitational field generated by a mass term and the initial surface through covariant retarded Green's function for linearized gravity in de Sitter spacetime was studied recently [4, 5] with the covariant gauges set to β = 2/3 and α = 5/3. In this paper we extend the work to restore the gauge parameter α in the field coming from the initial data using the method of shifting the parameter. The α terms in the initial field cancels exactly with the one coming from the source term. Consequently, the correct field configuration, with two equal mass points moving in itsmore » geodesic, one located at the North pole and another one located at the South pole, is reproduced in the whole manifold of de Sitter spacetime.« less

The Effects of Crossflow on the Pressures and Lift Induced by the Fountain Generated Between Two Impinging Jets

NASA Technical Reports Server (NTRS)

Kuhn, Richard E.

1998-01-01

When a jet STOVL aircraft is hovering, or in a crossflow, while close to the ground wall jets flowing radially outward from the impingement points of the jets are generated. An upflow, or fountain, is generated where the wall jets from adjacent jets meet on the ground surface. The induced lift and suckdown generated by the impingement of the fountain on the lower surface of the configuration has been the subject of previous studies. This study analyzes the limited available pressure and force data on the effect of crossflow on the fountain induced lift and suckdown. The analysis includes the effects of jet spacing, height and operating conditions. However, it is limited to twin jet configurations of circular, vertical jets operating at subcritical nozzle pressure ratios over a fixed ground surface.

Operation in the turbulent jet field of a linear array of multiple rectangular jets using a two-dimensional jet (Variation of mean velocity field)

NASA Astrophysics Data System (ADS)

Fujita, Shigetaka; Harima, Takashi

2016-03-01

The mean flowfield of a linear array of multiple rectangular jets run through transversely with a two-dimensional jet, has been investigated, experimentally. The object of this experiment is to operate both the velocity scale and the length scale of the multiple rectangular jets using a two-dimensional jet. The reason of the adoption of this nozzle exit shape was caused by the reports of authors in which the cruciform nozzle promoted the inward secondary flows strongly on both the two jet axes. Aspect ratio of the rectangular nozzle used in this experiment was 12.5. Reynolds number based on the nozzle width d and the exit mean velocity Ue (≅ 39 m / s) was kept constant 25000. Longitudinal mean velocity was measured using an X-array Hot-Wire Probe (lh = 3.1 μm in diameter, dh = 0.6 mm effective length : dh / lh = 194) operated by the linearized constant temperature anemometers (DANTEC), and the spanwise and the lateral mean velocities were measured using a yaw meter. The signals from the anemometers were passed through the low-pass filters and sampled using A.D. converter. The processing of the signals was made by a personal computer. Acquisition time of the signals was usually 60 seconds. From this experiment, it was revealed that the magnitude of the inward secondary flows on both the y and z axes in the upstream region of the present jet was promoted by a two-dimensional jet which run through transversely perpendicular to the multiple rectangular jets, therefore the potential core length on the x axis of the present jet extended 2.3 times longer than that of the multiple rectangular jets, and the half-velocity width on the rectangular jet axis of the present jet was suppressed 41% shorter compared with that of the multiple rectangular jets.

Near-Field Noise Computation for a Supersonic Circular Jet

NASA Technical Reports Server (NTRS)

Loh, Ching Y.; Hultgren, Lennart S.

2005-01-01

A fully expanded, high-Reynolds-number, supersonic circular jet of Mach number 1.4 is simulated, using a 3-D finite-volume Navier-Stokes solver, with emphasis on the near field noise. The numerical results are generally in good agreement with existing experimental findings.

Common origin of 3.55 keV x-ray line and gauge coupling unification with left-right dark matter

NASA Astrophysics Data System (ADS)

Borah, Debasish; Dasgupta, Arnab; Patra, Sudhanwa

2017-12-01

We present a minimal left-right dark matter framework that can simultaneously explain the recently observed 3.55 keV x-ray line from several galaxy clusters and gauge coupling unification at high energy scale. Adopting a minimal dark matter strategy, we consider both left and right handed triplet fermionic dark matter candidates which are stable by virtue of a remnant Z2≃(-1 )B -L symmetry arising after the spontaneous symmetry breaking of left-right gauge symmetry to that of the standard model. A scalar bitriplet field is incorporated whose first role is to allow radiative decay of right handed triplet dark matter into the left handed one and a photon with energy 3.55 keV. The other role this bitriplet field at TeV scale plays is to assist in achieving gauge coupling unification at a high energy scale within a nonsupersymmetric S O (10 ) model while keeping the scale of left-right gauge symmetry around the TeV corner. Apart from solving the neutrino mass problem and giving verifiable new contributions to neutrinoless double beta decay and charged lepton flavor violation, the model with TeV scale gauge bosons can also give rise to interesting collider signatures like diboson excess, dilepton plus two jets excess reported recently in the large hadron collider data.

On an acoustic field generated by subsonic jet at low Reynolds numbers

NASA Technical Reports Server (NTRS)

Yamamoto, K.; Arndt, R. E. A.

1978-01-01

An acoustic field generated by subsonic jets at low Reynolds numbers was investigated. This work is motivated by the need to increase the fundamental understanding of the jet noise generation mechanism which is essential to the development of further advanced techniques of noise suppression. The scope of this study consists of two major investigation. One is a study of large scale coherent structure in the jet turbulence, and the other is a study of the Reynolds number dependence of jet noise. With this in mind, extensive flow and acoustic measurements in low Reynolds number turbulent jets (8,930 less than or equal to M less than or equal to 220,000) were undertaken using miniature nozzles of the same configuration but different diameters at various exist Mach numbers (0.2 less than or equal to M less than or equal to 0.9).

Radiatively driven relativistic jets in Schwarzschild space-time

NASA Astrophysics Data System (ADS)

Vyas, Mukesh K.; Chattopadhyay, Indranil

2018-06-01

Context. Aims: We carry out a general relativistic study of radiatively driven conical fluid jets around non-rotating black holes and investigate the effects and significance of radiative acceleration, as well as radiation drag. Methods: We apply relativistic equations of motion in curved space-time around a Schwarzschild black hole for axis-symmetric one-dimensional jet in steady state, plying through the radiation field of the accretion disc. Radiative moments are computed using information of curved space-time. Slopes of physical variables at the sonic points are found using L'Hôpital's rule and employing Runge-Kutta's fourth order method to solve equations of motion. The analysis is carried out using the relativistic equation of state of the jet fluid. Results: The terminal speed of the jet depends on how much thermal energy is converted into jet momentum and how much radiation momentum is deposited onto the jet. Many classes of jet solutions with single sonic points, multiple sonic points, as well as those having radiation driven internal shocks are obtained. Variation of all flow variables along the jet-axis has been studied. Highly energetic electron-proton jets can be accelerated by intense radiation to terminal Lorentz factors γT 3. Moderate terminal speed vT 0.5 is obtained for moderately luminous discs. Lepton dominated jets may achieve γT 10. Conclusions: Thermal driving of the jet itself and radiation driving by accretion disc photons produce a wide-ranging jet solutions starting from moderately strong jets to the relativistic ones. Interplay of intensity, the nature of the radiation field, and the energetics of the jet result in a variety of jet solutions. We show that radiation field is able to induce steady shocks in jets, one of the criteria to explain high-energy power-law emission observed in spectra of some of the astrophysical objects.

An almost trivial gauge theory in the limit of infinite gauge coupling constant.

NASA Astrophysics Data System (ADS)

Kaptanoglu, S.

A local SU(2) gauge theory with one multiplet of scalars in the adjoint representation is considered. In the limit of infinite gauge coupling constant Yang-Mills fields become auxiliary and the action possesses a larger invariance than the usual gauge invariance; hence, the system develops a richer structure of constraints. The constraint analysis is carried out.

Model with a gauged lepton flavor SU(2) symmetry

NASA Astrophysics Data System (ADS)

Chiang, Cheng-Wei; Tsumura, Koji

2018-05-01

We propose a model having a gauged SU(2) symmetry associated with the second and third generations of leptons, dubbed SU(2) μτ , of which U{(1)}_{L_{μ }-L_{τ }} is an Abelian subgroup. In addition to the Standard Model fields, we introduce two types of scalar fields. One exotic scalar field is an SU(2) μτ doublet and SM singlet that develops a nonzero vacuum expectation value at presumably multi-TeV scale to completely break the SU(2) μτ symmetry, rendering three massive gauge bosons. At the same time, the other exotic scalar field, carrying electroweak as well as SU(2) μτ charges, is induced to have a nonzero vacuum expectation value as well and breaks mass degeneracy between the muon and tau. We examine how the new particles in the model contribute to the muon anomalous magnetic moment in the parameter space compliant with the Michel decays of tau.

Characteristic classes of gauge systems

NASA Astrophysics Data System (ADS)

Lyakhovich, S. L.; Sharapov, A. A.

2004-12-01

We define and study invariants which can be uniformly constructed for any gauge system. By a gauge system we understand an (anti-)Poisson supermanifold provided with an odd Hamiltonian self-commuting vector field called a homological vector field. This definition encompasses all the cases usually included into the notion of a gauge theory in physics as well as some other similar (but different) structures like Lie or Courant algebroids. For Lagrangian gauge theories or Hamiltonian first class constrained systems, the homological vector field is identified with the classical BRST transformation operator. We define characteristic classes of a gauge system as universal cohomology classes of the homological vector field, which are uniformly constructed in terms of this vector field itself. Not striving to exhaustively classify all the characteristic classes in this work, we compute those invariants which are built up in terms of the first derivatives of the homological vector field. We also consider the cohomological operations in the space of all the characteristic classes. In particular, we show that the (anti-)Poisson bracket becomes trivial when applied to the space of all the characteristic classes, instead the latter space can be endowed with another Lie bracket operation. Making use of this Lie bracket one can generate new characteristic classes involving higher derivatives of the homological vector field. The simplest characteristic classes are illustrated by the examples relating them to anomalies in the traditional BV or BFV-BRST theory and to characteristic classes of (singular) foliations.

Simultaneous planar measurements of soot structure and velocity fields in a turbulent lifted jet flame at 3 kHz

NASA Astrophysics Data System (ADS)

Köhler, M.; Boxx, I.; Geigle, K. P.; Meier, W.

2011-05-01

We describe a newly developed combustion diagnostic for the simultaneous planar imaging of soot structure and velocity fields in a highly sooting, lifted turbulent jet flame at 3000 frames per second, or two orders of magnitude faster than "conventional" laser imaging systems. This diagnostic uses short pulse duration (8 ns), frequency-doubled, diode-pumped solid state (DPSS) lasers to excite laser-induced incandescence (LII) at 3 kHz, which is then imaged onto a high framerate CMOS camera. A second (dual-cavity) DPSS laser and CMOS camera form the basis of a particle image velocity (PIV) system used to acquire 2-component velocity field in the flame. The LII response curve (measured in a laminar propane diffusion flame) is presented and the combined diagnostics then applied in a heavily sooting lifted turbulent jet flame. The potential challenges and rewards of application of this combined imaging technique at high speeds are discussed.

From 6D superconformal field theories to dynamic gauged linear sigma models

NASA Astrophysics Data System (ADS)

Apruzzi, Fabio; Hassler, Falk; Heckman, Jonathan J.; Melnikov, Ilarion V.

2017-09-01

Compactifications of six-dimensional (6D) superconformal field theories (SCFTs) on four- manifolds generate a large class of novel two-dimensional (2D) quantum field theories. We consider in detail the case of the rank-one simple non-Higgsable cluster 6D SCFTs. On the tensor branch of these theories, the gauge group is simple and there are no matter fields. For compactifications on suitably chosen Kähler surfaces, we present evidence that this provides a method to realize 2D SCFTs with N =(0 ,2 ) supersymmetry. In particular, we find that reduction on the tensor branch of the 6D SCFT yields a description of the same 2D fixed point that is described in the UV by a gauged linear sigma model (GLSM) in which the parameters are promoted to dynamical fields, that is, a "dynamic GLSM" (DGLSM). Consistency of the model requires the DGLSM to be coupled to additional non-Lagrangian sectors obtained from reduction of the antichiral two-form of the 6D theory. These extra sectors include both chiral and antichiral currents, as well as spacetime filling noncritical strings of the 6D theory. For each candidate 2D SCFT, we also extract the left- and right-moving central charges in terms of data of the 6D SCFT and the compactification manifold.

Gauge invariant lattice quantum field theory: Implications for statistical properties of high frequency financial markets

NASA Astrophysics Data System (ADS)

Dupoyet, B.; Fiebig, H. R.; Musgrove, D. P.

2010-01-01

We report on initial studies of a quantum field theory defined on a lattice with multi-ladder geometry and the dilation group as a local gauge symmetry. The model is relevant in the cross-disciplinary area of econophysics. A corresponding proposal by Ilinski aimed at gauge modeling in non-equilibrium pricing is implemented in a numerical simulation. We arrive at a probability distribution of relative gains which matches the high frequency historical data of the NASDAQ stock exchange index.

An ionization pressure gauge with LaB6 emitter for long-term operation in strong magnetic fields

NASA Astrophysics Data System (ADS)

Wenzel, U.; Pedersen, T. S.; Marquardt, M.; Singer, M.

2018-03-01

We report here on a potentially significant improvement in the design of neutral pressure gauges of the so-called ASDEX-type which were first used in the Axially Symmetric Divertor EXperiment (ASDEX). Such gauges are considered state-of-the-art and are in wide use in fusion experiments, but they nonetheless suffer from a relatively high failure rate when operated at high magnetic field strengths for long times. This is therefore a significant concern for long-pulse, high-field experiments such as Wendelstein 7-X (W7-X) and ITER. The new design is much more robust. The improvement is to use a LaB6 crystal instead of a tungsten wire as the thermionic emitter of electrons in the gauge. Such a LaB6 prototype gauge was successfully operated for a total of 60 h in B = 3.1 T, confirming the significantly improved robustness of the new design and qualifying it for near-term operation in W7-X. With the LaB6 crystal, an order of magnitude reduction in heating current is achieved, relative to the tungsten filament based gauges, from 15-20 A to 1-2 A. This reduces the Lorenz forces and the heating power by an order of magnitude also and is presumably the reason for the much improved robustness. The new gauge design, test environment setup at the superconducting magnet, and results from test operation are described.

Simultaneous velocity and concentration field measurements of passive-scalar mixing in a confined rectangular jet

NASA Astrophysics Data System (ADS)

Feng, Hua; Olsen, Michael G.; Hill, James C.; Fox, Rodney O.

2007-06-01

Simultaneous velocity and concentration fields in a confined liquid-phase rectangular jet with a Reynolds number based on the hydraulic diameter of 50,000 (or 10,000 based on the velocity difference between streams and the jet exit dimension) and a Schmidt number of 1,250 were obtained by means of a combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) system. Data were collected at the jet exit and six further downstream locations. The velocity and concentration field data were analyzed for flow statistics such as turbulent fluxes, turbulent viscosity and diffusivity, and turbulent Schmidt number ( Sc T ). The streamwise turbulent flux was found to be larger than the transverse turbulent flux, and the mean concentration gradient was not aligned with the turbulent flux vector. The average Sc T was found to vary both in streamwise and in cross stream directions and had a mean value around 0.8, a value consistent with the literature. Spatial correlation fields of turbulent fluxes and concentration were then determined. The R u'ϕ' correlation was elliptical in shape with a major axis tilted downward with respect to the streamwise axis, whereas the R v'ϕ' correlation was an ellipse with a major axis aligned with the cross-stream direction. Negative regions of R u'ϕ' were observed in the outer streams, and these negatively correlated regions decayed with downstream distance and finally disappeared altogether. The R ϕ'ϕ' correlation field was found to be an ellipse with the major axis inclined at about 45° with respect to the streamwise direction. Linear stochastic estimation was used to interpret spatial correlation data and to determine conditional flow structures. It is believed that a vortex street formed near the splitter plate is responsible for the negatively correlated region observed in the R u'ϕ' spatial correlations of turbulent fluxes. A positive concentration fluctuation event was observed to correspond to a finger of

Field testing of jet-grouted piles and drilled shafts.

DOT National Transportation Integrated Search

2014-01-01

A field study of deep foundations supporting high mast lighting and signage was undertaken in typical Florida : soils. Three drilled shafts (48 in x12 ft and two 48 in x18 ft) and two jet-grouted piles (28 in x18 ft) were : constructed in Keystone He...

Observational and Model Analysis of a Two-ribbon Flare Possibly Induced by a Neighboring Blowout Jet

NASA Astrophysics Data System (ADS)

Joshi, Bhuwan; Thalmann, Julia K.; Mitra, Prabir K.; Chandra, Ramesh; Veronig, Astrid M.

2017-12-01

In this paper, we present unique observations of a blowout coronal jet that possibly triggered a two-ribbon confined C1.2 flare in bipolar solar active region NOAA 12615 on 2016 December 5. The jet activity initiates at chromospheric/transition region heights with a small brightening that eventually increases in volume, with well-developed standard morphological jet features, viz., base and spire. The spire widens up with a collimated eruption of cool and hot plasma components, observed in the 304 and 94 Å channels of AIA, respectively. The speed of the plasma ejection, which forms the jet’s spire, was higher for the hot component (˜200 km s-1) than the cooler one (˜130 km s-1). The NLFF model of coronal fields at the pre- and post-jet phases successfully reveals openings of previously closed magnetic field lines with a rather inclined/low-lying jet structure. The peak phase of the jet emission is followed by the development of a two-ribbon flare that shows coronal loop emission in HXRs up to ˜25 keV energy. The coronal magnetic fields rooted at the location of EUV flare ribbons, derived from the NLFF model, demonstrate the pre-flare phase to exhibit an “X-type” configuration, while the magnetic fields at the post-flare phase are more or less oriented parallel. Comparisons of multi-wavelength measurements with the magnetic field extrapolations suggest that the jet activity likely triggered the two-ribbon flare by perturbing the field in the interior of the active region.

Non-integrable dynamics of matter-wave solitons in a density-dependent gauge theory

NASA Astrophysics Data System (ADS)

Dingwall, R. J.; Edmonds, M. J.; Helm, J. L.; Malomed, B. A.; Öhberg, P.

2018-04-01

We study interactions between bright matter-wave solitons which acquire chiral transport dynamics due to an optically-induced density-dependent gauge potential. Through numerical simulations, we find that the collision dynamics feature several non-integrable phenomena, from inelastic collisions including population transfer and radiation losses to the formation of short-lived bound states and soliton fission. An effective quasi-particle model for the interaction between the solitons is derived by means of a variational approximation, which demonstrates that the inelastic nature of the collision arises from a coupling of the gauge field to velocities of the solitons. In addition, we derive a set of interaction potentials which show that the influence of the gauge field appears as a short-range potential, that can give rise to both attractive and repulsive interactions.

Electrically tunable artificial gauge potential for polaritons

PubMed Central

Lim, Hyang-Tag; Togan, Emre; Kroner, Martin; Miguel-Sanchez, Javier; Imamoğlu, Atac

2017-01-01

Neutral particles subject to artificial gauge potentials can behave as charged particles in magnetic fields. This fascinating premise has led to demonstrations of one-way waveguides, topologically protected edge states and Landau levels for photons. In ultracold neutral atoms, effective gauge fields have allowed the emulation of matter under strong magnetic fields leading to realization of Harper-Hofstadter and Haldane models. Here we show that application of perpendicular electric and magnetic fields effects a tunable artificial gauge potential for two-dimensional microcavity exciton polaritons. For verification, we perform interferometric measurements of the associated phase accumulated during coherent polariton transport. Since the gauge potential originates from the magnetoelectric Stark effect, it can be realized for photons strongly coupled to excitations in any polarizable medium. Together with strong polariton–polariton interactions and engineered polariton lattices, artificial gauge fields could play a key role in investigation of non-equilibrium dynamics of strongly correlated photons. PMID:28230047

Foreign exchange market as a lattice gauge theory

NASA Astrophysics Data System (ADS)

Young, K.

1999-10-01

A simple model of the foreign exchange market is exactly a lattice gauge theory. Exchange rates are the exponentials of gauge potentials defined on spatial links while interest rates are related to gauge potentials on temporal links. Arbitrage opportunities are given by nonzero values of the gauge-invariant field tensor or curvature defined on closed loops. Arbitrage opportunities involving cross-rates at one time are "magnetic fields," while arbitrage opportunities involving future contracts are "electric fields."

On inducing finite dimensional physical field representations for massless particles in even dimensions

NASA Technical Reports Server (NTRS)

Bhansali, Vineer

1993-01-01

Assuming trivial action of Euclidean translations, the method of induced representations is used to derive a correspondence between massless field representations transforming under the full generalized even dimensional Lorentz group, and highest weight states of the relevant little group. This gives a connection between 'helicity' and 'chirality' in all dimensions. Restrictions on 'gauge independent' representations for physical particles that this induction imposes are also stated.

Reconnection-Driven Coronal-Hole Jets with Gravity and Solar Wind

NASA Technical Reports Server (NTRS)

Karpen, J. T.; Devore, C. R.; Antiochos, S. K.; Pariat, E.

2017-01-01

Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry,gravity, and solar wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfven wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfven waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.

Regularization of the light-cone gauge gluon propagator singularities using sub-gauge conditions

DOE PAGES

Chirilli, Giovanni A.; Kovchegov, Yuri V.; Wertepny, Douglas E.

2015-12-21

Perturbative QCD calculations in the light-cone gauge have long suffered from the ambiguity associated with the regularization of the poles in the gluon propagator. In this work we study sub-gauge conditions within the light-cone gauge corresponding to several known ways of regulating the gluon propagator. By using the functional integral calculation of the gluon propagator, we rederive the known sub-gauge conditions for the θ-function gauges and identify the sub-gauge condition for the principal value (PV) regularization of the gluon propagator’s light-cone poles. The obtained sub-gauge condition for the PV case is further verified by a sample calculation of the classicalmore » Yang-Mills field of two collinear ultrarelativistic point color charges. Our method does not allow one to construct a sub-gauge condition corresponding to the well-known Mandelstam-Leibbrandt prescription for regulating the gluon propagator poles.« less

Rectangular subsonic jet flow field measurements

NASA Technical Reports Server (NTRS)

Morrison, Gerald L.; Swan, David H.

1990-01-01

Flow field measurements of three subsonic rectangular cold air jets are presented. The three cases had aspect ratios of 1x2, 1x4 at a Mach number of 0.09 and an aspect ratio of 1x2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemometer system. The data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data are presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made.

Field correlation of PQI gauge with nuclear density gauge: phase 1.

DOT National Transportation Integrated Search

2006-12-01

Traditionally, the Oklahoma Department of Transportation (ODOT) uses a nuclear density gauge as a quality control (QC) and quality assurance (QA) tool for in-place density. The nuclear-based devices, however, tend to have problems associated with lic...

Organized motions in a jet in crossflow

NASA Astrophysics Data System (ADS)

Rivero, A.; Ferré, J. A.; Giralt, Francesc

2001-10-01

An experimental study to identify the structures present in a jet in crossflow has been carried out at a jet-to-crossflow velocity ratio U/Ucf = 3.8 and Reynolds number Re = UcfD/v = 6600. The hot-wire velocity data measured with a rake of eight X-wires at x/D = 5 and 15 and flow visualizations using planar laser-induced fluorescence (PLIF) confirm that the well-established pair of counter-rotating vortices is a feature of the mean field and that the upright, tornado-like or Fric's vortices that are shed to the leeward side of the jet are connected to the jet flow at the core. The counter-rotating vortex pair is strongly modulated by a coherent velocity field that, in fact, is as important as the mean velocity field. Three different structures folded vortex rings, horseshoe vortices and handle-type structures contribute to this coherent field. The new handle-like structures identified in the current study link the boundary layer vorticity with the counter-rotating vortex pair through the upright tornado-like vortices. They are responsible for the modulation and meandering of the counter-rotating vortex pair observed both in video recordings of visualizations and in the instantaneous velocity field. These results corroborate that the genesis of the dominant counter-rotating vortex pair strongly depends on the high pressure gradients that develop in the region near the jet exit, both inside and outside the nozzle.

Field Jet Erosion Tests on the Mississippi River Collocated Demonstration Section, Plaquemines Parish, Louisiana

DTIC Science & Technology

2015-06-01

ash/bed-ash blend treatment, and the second segment was constructed of Bonnet Carré clay treated with lime . In addition, a section of untreated clay...on the original levee was also tested. The field JET data showed that the clay treated with lime was categorized as resistant to very resistant. The...treatments reduced the erodibility of the soil. However, the field JET results showed that lime treatment performed better at reducing erosion than the

Singular gauge transformation and the Erler-Maccaferri solution in bosonic open string field theory

NASA Astrophysics Data System (ADS)

Miwa, Akitsugu; Sugita, Kazuhiro

2017-09-01

We study candidate multiple-brane solutions of bosonic open string field theory. They are constructed by performing a singular gauge transformation n times for the Erler-Maccaferri solution. We check the equation of motion in the strong sense, and find that it is satisfied only when we perform the gauge transformation once. We calculate the energy for that case and obtain a support that the solution is a multiple-brane solution. We also check the tachyon profile for a specific solution that we interpret as describing a D24-brane placed on a D25-brane.

How can we probe the atom mass currents induced by synthetic gauge fields?

NASA Astrophysics Data System (ADS)

Paramekanti, Arun; Killi, Matthew; Trotzky, Stefan

2013-05-01

Ultracold atomic fermions and bosons in an optical lattice can have quantum ground states which support equilibrium currents in the presence of synthetic magnetic fields or spin orbit coupling. As a tool to uncover these mass currents, we propose using an anisotropic quantum quench of the optical lattice which dynamically converts the current patterns into measurable density patterns. Using analytical calculations and numerical simulations, we show that this scheme can probe diverse equilibrium bulk current patterns in Bose superfluids and Fermi fluids induced by synthetic magnetic fields, as well as detect the chiral edge currents in topological states of atomic matter such as quantum Hall and quantum spin Hall insulators. This work is supported by NSERC of Canada and the Canadian Institute for Advanced Research.

Coronal Jet Collimation by Nonlinear Induced Flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasheghani Farahani, S.; Hejazi, S. M.

2017-08-01

Our objective is to study the collimation of solar jets by nonlinear forces corresponding to torsional Alfvén waves together with external forces. We consider a straight, initially non-rotating, untwisted magnetic cylinder embedded in a plasma with a straight magnetic field, where a shear between the internal and external flows exists. By implementing magnetohydrodynamic theory and taking into account the second-order thin flux tube approximation, the balance between the internal nonlinear forces is visualized. The nonlinear differential equation containing the ponderomotive, magnetic tension, and centrifugal forces in the presence of the shear flow is obtained. The solution presents the scale ofmore » influence of the propagating torsional Alfvén wave on compressive perturbations. Explicit expressions for the compressive perturbations caused by the forces connected to the torsional Alfvén wave show that, in the presence of a shear flow, the magnetic tension and centrifugal forces do not cancel each other’s effects as they did in its absence. This shear flow plays in favor of the magnetic tension force, resulting in a more efficient collimation. Regarding the ponderomotive force, the shear flow has no effect. The phase relations highlight the interplay of the shear flow and the plasma- β . As the shear flow and plasma- β increase, compressive perturbation amplitudes emerge. We conclude that the jet collimation due to the torsional Alfvén wave highly depends on the location of the jet. The shear flow tightens the collimation as the jet elevates up to the solar corona.« less

Coronal Jet Collimation by Nonlinear Induced Flows

NASA Astrophysics Data System (ADS)

Vasheghani Farahani, S.; Hejazi, S. M.

2017-08-01

Our objective is to study the collimation of solar jets by nonlinear forces corresponding to torsional Alfvén waves together with external forces. We consider a straight, initially non-rotating, untwisted magnetic cylinder embedded in a plasma with a straight magnetic field, where a shear between the internal and external flows exists. By implementing magnetohydrodynamic theory and taking into account the second-order thin flux tube approximation, the balance between the internal nonlinear forces is visualized. The nonlinear differential equation containing the ponderomotive, magnetic tension, and centrifugal forces in the presence of the shear flow is obtained. The solution presents the scale of influence of the propagating torsional Alfvén wave on compressive perturbations. Explicit expressions for the compressive perturbations caused by the forces connected to the torsional Alfvén wave show that, in the presence of a shear flow, the magnetic tension and centrifugal forces do not cancel each other’s effects as they did in its absence. This shear flow plays in favor of the magnetic tension force, resulting in a more efficient collimation. Regarding the ponderomotive force, the shear flow has no effect. The phase relations highlight the interplay of the shear flow and the plasma-β. As the shear flow and plasma-β increase, compressive perturbation amplitudes emerge. We conclude that the jet collimation due to the torsional Alfvén wave highly depends on the location of the jet. The shear flow tightens the collimation as the jet elevates up to the solar corona.

The energy-momentum tensor(s) in classical gauge theories

DOE PAGES

Blaschke, Daniel N.; Gieres, François; Reboud, Méril; ...

2016-07-12

We give an introduction to, and review of, the energy-momentum tensors in classical gauge field theories in Minkowski space, and to some extent also in curved space-time. For the canonical energy-momentum tensor of non-Abelian gauge fields and of matter fields coupled to such fields, we present a new and simple improvement procedure based on gauge invariance for constructing a gauge invariant, symmetric energy-momentum tensor. In conclusion, the relationship with the Einstein-Hilbert tensor following from the coupling to a gravitational field is also discussed.

Jet-induced star formation by accreting black holes: impact on stellar, galaxy, and cosmic evolution

NASA Astrophysics Data System (ADS)

Mirabel, Igor Felix

2016-07-01

Evidence that relativistic jets trigger star formation along their axis has been found associated to low redshift and high redshift accreting supermassive black holes. However, the physical processes by which jet-cloud interaction may trigger star formation has so far not been elucidated. To gain insight into this potentially important star formation mechanism during reionization, when microquasars were form prolifically before AGN, our international team is carrying out a muliwavelength study of a microquasar jet-induced star formation region in the Milky Way using data from space missions (Chandra, Integral, ISO, Herschel) and from the ground (at cm and mm wavelengths with the VLA and IRAM, and IR with Gemini and VLT). I will show that this relative nearby star forming region is an ideal laboratory to test models of jet-induced star formation elsewhere in the universe.

Far-field tsunami magnitude determined from ocean-bottom pressure gauge data around Japan

NASA Astrophysics Data System (ADS)

Baba, T.; Hirata, K.; Kaneda, Y.

2003-12-01

\\hspace*{3mm}Tsunami magnitude is the most fundamental parameter to scale tsunamigenic earthquakes. According to Abe (1979), the tsunami magnitude, Mt, is empirically related to the crest to trough amplitude, H, of the far-field tsunami wave in meters (Mt = logH + 9.1). Here we investigate the far-field tsunami magnitude using ocean-bottom pressure gauge data. The recent ocean-bottom pressure measurements provide more precise tsunami data with a high signal-to-noise ratio. \\hspace*{3mm}Japan Marine Science and Technology Center is monitoring ocean bottom pressure fluctuations using two submarine cables of depths of 1500 - 2400 m. These geophysical observatory systems are located off Cape Muroto, Southwest Japan, and off Hokkaido, Northern Japan. The ocean-bottom pressure data recorded with the Muroto and Hokkaido systems have been collected continuously since March, 1997 and October, 1999, respectively. \\hspace*{3mm}Over the period from March 1997 to June 2003, we have observed four far-field tsunami signals, generated by earthquakes, on ocean-bottom pressure records. These far-field tsunamis were generated by the 1998 Papua New Guinea eq. (Mw 7.0), 1999 Vanuatu eq. (Mw 7.2), 2001 Peru eq. (Mw 8.4) and 2002 Papua New Guinea eq. (Mw 7.6). Maximum amplitude of about 30 mm was recorded by the tsunami from the 2001 Peru earthquake. \\hspace*{3mm}Direct application of the Abe's empirical relation to ocean-bottom pressure gauge data underestimates tsunami magnitudes by about an order of magnitude. This is because the Abe's empirical relation was derived only from tsunami amplitudes with coastal tide gauges where tsunami is amplified by the shoaling of topography and the reflection at the coastline. However, these effects do not work for offshore tsunami in deep oceans. In general, amplification due to shoaling near the coastline is governed by the Green's Law, in which the tsunami amplitude is proportional to h-1/4, where h is the water depth. Wave amplitude also is

Mast cells mediate the immune suppression induced by dermal exposure to JP-8 jet fuel.

PubMed

Limón-Flores, Alberto Y; Chacón-Salinas, Rommel; Ramos, Gerardo; Ullrich, Stephen E

2009-11-01

Applying jet propulsion-8 (JP-8) jet fuel to the skin of mice induces immune suppression. Applying JP-8 to the skin of mice suppresses T-cell-mediated immune reactions including, contact hypersensitivity (CHS) delayed-type hypersensitivity and T-cell proliferation. Because dermal mast cells play an important immune regulatory role in vivo, we tested the hypothesis that mast cells mediate jet fuel-induced immune suppression. When we applied JP-8 to the skin of mast cell deficient mice CHS was not suppressed. Reconstituting mast cell deficient mice with wild-type bone marrow derived mast cells (mast cell "knock-in mice") restored JP-8-induced immune suppression. When, however, mast cells from prostaglandin E(2) (PGE(2))-deficient mice were used, the ability of JP-8 to suppress CHS was not restored, indicating that mast cell-derived PGE(2) was activating immune suppression. Examining the density of mast cells in the skin and lymph nodes of JP-8-treated mice indicated that jet fuel treatment caused an initial increase in mast cell density in the skin, followed by increased numbers of mast cells in the subcutaneous space and then in draining lymph nodes. Applying JP-8 to the skin increased mast cell expression of CXCR4, and increased the expression of CXCL12 by draining lymph node cells. Because CXCL12 is a chemoattractant for CXCR4+ mast cells, we treated JP-8-treated mice with AMD3100, a CXCR4 antagonist. AMD3100 blocked the mobilization of mast cells to the draining lymph node and inhibited JP-8-induced immune suppression. Our findings demonstrate the importance of mast cells in mediating jet fuel-induced immune suppression.

Flow field topology of submerged jets with fractal generated turbulence

NASA Astrophysics Data System (ADS)

Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso

2015-11-01

Fractal grids (FGs) have been recently an object of numerous investigations due to the interesting capability of generating turbulence at multiple scales, thus paving the way to tune mixing and scalar transport. The flow field topology of a turbulent air jet equipped with a square FG is investigated by means of planar and volumetric particle image velocimetry. The comparison with the well-known features of a round jet without turbulence generators is also presented. The Reynolds number based on the nozzle exit section diameter for all the experiments is set to about 15 000. It is demonstrated that the presence of the grid enhances the entrainment rate and, as a consequence, the scalar transfer of the jet. Moreover, due to the effect of the jet external shear layer on the wake shed by the grid bars, the turbulence production region past the grid is significantly shortened with respect to the documented behavior of fractal grids in free-shear conditions. The organization of the large coherent structures in the FG case is also analyzed and discussed. Differently from the well-known generation of toroidal vortices due to the growth of azimuthal disturbances within the jet shear layer, the fractal grid introduces cross-wise disturbs which produce streamwise vortices; these structures, although characterized by a lower energy content, have a deeper streamwise penetration than the ring vortices, thus enhancing the entrainment process.

Gauge invariance for a whole Abelian model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauca, J.; Doria, R.; Soares, W.

Light invariance is a fundamental principle for physics be done. It generates Maxwell equations, relativity, Lorentz group. However there is still space for a fourth picture be developed which is to include fields with same Lorentz nature. It brings a new room for field theory. It says that light invariance does not work just to connect space and time but it also associates different fields with same nature. Thus for the ((1/2),(1/2)) representation there is a fields family {l_brace}A{sub {mu}I}{r_brace} to be studied. This means that given such fields association one should derive its corresponding gauge theory. This is themore » effort at this work. Show that there is a whole gauge theory to cover these fields relationships. Considering the abelian case, prove its gauge invariance. It yields the kinetic, massive, trilinear and quadrilinear gauge invariant terms.« less

Including gauge-group parameters into the theory of interactions: an alternative mass-generating mechanism for gauge fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aldaya, V.; Lopez-Ruiz, F. F.; Sanchez-Sastre, E.

2006-11-03

We reformulate the gauge theory of interactions by introducing the gauge group parameters into the model. The dynamics of the new 'Goldstone-like' bosons is accomplished through a non-linear {sigma}-model Lagrangian. They are minimally coupled according to a proper prescription which provides mass terms to the intermediate vector bosons without spoiling gauge invariance. The present formalism is explicitly applied to the Standard Model of electroweak interactions.

Gauged twistor spinors and symmetry operators

NASA Astrophysics Data System (ADS)

Ertem, Ümit

2017-03-01

We consider gauged twistor spinors which are supersymmetry generators of supersymmetric and superconformal field theories in curved backgrounds. We show that the spinor bilinears of gauged twistor spinors satisfy the gauged conformal Killing-Yano equation. We prove that the symmetry operators of the gauged twistor spinor equation can be constructed from ordinary conformal Killing-Yano forms in constant curvature backgrounds. This provides a way to obtain gauged twistor spinors from ordinary twistor spinors.

Evidence for Helical Magnetic fields in Kiloparsec-Scale AGN Jets and the Action of a Cosmic Battery

NASA Technical Reports Server (NTRS)

Gabuzda, D. C.; Christodoulou, D. M.; Contopulos, I.; Kazanas, D.

2012-01-01

A search for transverse kiloparsec-scale gradients in Faraday rotation-measure (RM) maps of extragalactic radio sources in the literature has yielded 6 AGNs displaying continuous, monotonic RM gradients across their jets, oriented roughly orthogonal to the local jet direction. The most natural interpretation of such transverse RM gradients is that they are caused by the systematic change in the line-of-sight components of helical magnetic fields associated with these jets. All the identified transverse RM gradients increase in the counterclockwise (CCW) direction on the sky relative to the centers of these AGNs. Taken together with the results of Contopoulos et al. who found evidence for a predominance of clockwise (CW) transverse RM gradients across parsec-scale (VLBI) jets, this provides new evidence for preferred orientations of RM gradients due to helical jet magnetic fields, with a reversal from CW in the inner jets to CCW farther from the centers of activity. This can be explained by the "Poynting-Robertson cosmic-battery" mechanism, which can generate helical magnetic fields with a. characteristic "twist," which are expelled with the jet outflows. If the Poynting-Robertson battery mechanism is not operating, an alternative mechanism must be identified, which is able to explain the 'predominance of CW /CCW RM gradients on parsec/kiloparsec scales.

Laboratory formation of a scaled protostellar jet by coaligned poloidal magnetic field.

PubMed

Albertazzi, B; Ciardi, A; Nakatsutsumi, M; Vinci, T; Béard, J; Bonito, R; Billette, J; Borghesi, M; Burkley, Z; Chen, S N; Cowan, T E; Herrmannsdörfer, T; Higginson, D P; Kroll, F; Pikuz, S A; Naughton, K; Romagnani, L; Riconda, C; Revet, G; Riquier, R; Schlenvoigt, H-P; Skobelev, I Yu; Faenov, A Ya; Soloviev, A; Huarte-Espinosa, M; Frank, A; Portugall, O; Pépin, H; Fuchs, J

2014-10-17

Although bipolar jets are seen emerging from a wide variety of astrophysical systems, the issue of their formation and morphology beyond their launching is still under study. Our scaled laboratory experiments, representative of young stellar object outflows, reveal that stable and narrow collimation of the entire flow can result from the presence of a poloidal magnetic field whose strength is consistent with observations. The laboratory plasma becomes focused with an interior cavity. This gives rise to a standing conical shock from which the jet emerges. Following simulations of the process at the full astrophysical scale, we conclude that it can also explain recently discovered x-ray emission features observed in low-density regions at the base of protostellar jets, such as the well-studied jet HH 154. Copyright © 2014, American Association for the Advancement of Science.

Experimental and Computational Induced Aerodynamics from Missile Jet Reaction Controls at Angles of Attack to 75 Degrees

NASA Technical Reports Server (NTRS)

Capone, Francis J.; Ashbury, Scott C.; Deere, Karen A.

1996-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine induced aerodynamic effects from jet reaction controls of an advanced air-to-air missile concept. The 75-percent scale model featured independently controlled reaction jets located near the nose and tail of the model. Aerodynamic control was provided by four fins located near the tail of the model. This investigation was conducted at Mach numbers of 0.35 and 0.60, at angles of attack up to 75 deg and at nozzle pressure ratios up to 90. Jet-reaction thrust forces were not measured by the force balance but jet-induced forces were. In addition, a multiblock three-dimensional Navier-Stokes method was used to calculate the flowfield of the missile at angles of attack up to 40 deg. Results indicate that large interference effects on pitching moment were induced from operating the nose jets with the the off. Excellent correlation between experimental and computational pressure distributions and pitching moment were obtained a a Mach number of 0.35 and at angles of attack up to 40 deg.

On the formulation of D=11 supergravity and the composite nature of its three-form gauge field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bandos, Igor A.; Institute for Theoretical Physics, NSC 'Kharkov Institute of Physics and Technology', UA61108, Kharkov; Azcarraga, Jose A. de

2005-05-01

The underlying gauge group structure of the D=11 Cremmer-Julia-Scherk supergravity becomes manifest when its three-form field A{sub 3} is expressed through a set of one-form gauge fields, B1a1a2, B1a1...a5, {eta}{sub 1{alpha}}, and E{sup a}, {psi}{sup {alpha}}. These are associated with the generators of the elements of a family of enlarged supersymmetry algebras E-bar (528 vertical bar 32+32)(s) parametrized by a real number s. We study in detail the composite structure of A{sub 3} extending previous results by D'Auria and Fre, stress the equivalence of the above problem to the trivialization of a standard supersymmetry algebra E(11 vertical bar 32) cohomologymore » four-cocycle on the enlarged E-bar (528 vertical bar 32+32)(s) superalgebras, and discuss its possible dynamical consequences. To this aim we consider the properties of the first order supergravity action with a composite A{sub 3} field and find the set of extra gauge symmetries that guarantee that the field theoretical degrees of freedom of the theory remain the same as with a fundamental A{sub 3}. The extra gauge symmetries are also present in the so-called rheonomic treatment of the first order D=11 supergravity action when A{sub 3} is composite. Our considerations on the composite structure of A{sub 3} provide one more application of the idea that there exists an extended superspace coordinates/fields correspondence. They also suggest that there is a possible embedding of D=11 supergravity into a theory defined on the enlarged superspace {sigma}-bar (528 vertical bar 32+32)(s)« less

RECONNECTION-DRIVEN CORONAL-HOLE JETS WITH GRAVITY AND SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karpen, J. T.; DeVore, C. R.; Antiochos, S. K.

Coronal-hole jets occur ubiquitously in the Sun's coronal holes, at EUV and X-ray bright points associated with intrusions of minority magnetic polarity. The embedded-bipole model for these jets posits that they are driven by explosive, fast reconnection between the stressed closed field of the embedded bipole and the open field of the surrounding coronal hole. Previous numerical studies in Cartesian geometry, assuming uniform ambient magnetic field and plasma while neglecting gravity and solar wind, demonstrated that the model is robust and can produce jet-like events in simple configurations. We have extended these investigations by including spherical geometry, gravity, and solarmore » wind in a nonuniform, coronal hole-like ambient atmosphere. Our simulations confirm that the jet is initiated by the onset of a kink-like instability of the internal closed field, which induces a burst of reconnection between the closed and external open field, launching a helical jet. Our new results demonstrate that the jet propagation is sustained through the outer corona, in the form of a traveling nonlinear Alfvén wave front trailed by slower-moving plasma density enhancements that are compressed and accelerated by the wave. This finding agrees well with observations of white-light coronal-hole jets, and can explain microstreams and torsional Alfvén waves detected in situ in the solar wind. We also use our numerical results to deduce scaling relationships between properties of the coronal source region and the characteristics of the resulting jet, which can be tested against observations.« less

Gauge interaction as periodicity modulation

NASA Astrophysics Data System (ADS)

Dolce, Donatello

2012-06-01

The paper is devoted to a geometrical interpretation of gauge invariance in terms of the formalism of field theory in compact space-time dimensions (Dolce, 2011) [8]. In this formalism, the kinematic information of an interacting elementary particle is encoded on the relativistic geometrodynamics of the boundary of the theory through local transformations of the underlying space-time coordinates. Therefore gauge interactions are described as invariance of the theory under local deformations of the boundary. The resulting local variations of the field solution are interpreted as internal transformations. The internal symmetries of the gauge theory turn out to be related to corresponding space-time local symmetries. In the approximation of local infinitesimal isometric transformations, Maxwell's kinematics and gauge invariance are inferred directly from the variational principle. Furthermore we explicitly impose periodic conditions at the boundary of the theory as semi-classical quantization condition in order to investigate the quantum behavior of gauge interaction. In the abelian case the result is a remarkable formal correspondence with scalar QED.

Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

NASA Astrophysics Data System (ADS)

Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

2017-09-01

Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

Spinor matter fields in SL(2,C) gauge theories of gravity: Lagrangian and Hamiltonian approaches

NASA Astrophysics Data System (ADS)

Antonowicz, Marek; Szczyrba, Wiktor

1985-06-01

We consider the SL(2,C)-covariant Lagrangian formulation of gravitational theories with the presence of spinor matter fields. The invariance properties of such theories give rise to the conservation laws (the contracted Bianchi identities) having in the presence of matter fields a more complicated form than those known in the literature previously. A general SL(2,C) gauge theory of gravity is cast into an SL(2,C)-covariant Hamiltonian formulation. Breaking the SL(2,C) symmetry of the system to the SU(2) symmetry, by introducing a spacelike slicing of spacetime, we get an SU(2)-covariant Hamiltonian picture. The qualitative analysis of SL(2,C) gauge theories of gravity in the SU(2)-covariant formulation enables us to define the dynamical symplectic variables and the gauge variables of the theory under consideration as well as to divide the set of field equations into the dynamical equations and the constraints. In the SU(2)-covariant Hamiltonian formulation the primary constraints, which are generic for first-order matter Lagrangians (Dirac, Weyl, Fierz-Pauli), can be reduced. The effective matter symplectic variables are given by SU(2)-spinor-valued half-forms on three-dimensional slices of spacetime. The coupled Einstein-Cartan-Dirac (Weyl, Fierz-Pauli) system is analyzed from the (3+1) point of view. This analysis is complete; the field equations of the Einstein-Cartan-Dirac theory split into 18 gravitational dynamical equations, 8 dynamical Dirac equations, and 7 first-class constraints. The system has 4+8=12 independent degrees of freedom in the phase space.

Localization of U(1) gauge vector field on flat branes with five-dimension (asymptotic) AdS5 spacetime

NASA Astrophysics Data System (ADS)

Zhao, Zhen-Hua; Xie, Qun-Ying

2018-05-01

In order to localize U(1) gauge vector field on Randall-Sundrum-like braneworld model with infinite extra dimension, we propose a new kind of non-minimal coupling between the U(1) gauge field and the gravity. We propose three kinds of coupling methods and they all support the localization of zero mode. In addition, one of them can support the localization of massive modes. Moreover, the massive tachyonic modes can be excluded. And our method can be used not only in the thin braneword models but also in the thick ones.

Review of non-nuclear density gauges as possible replacements for ITD's nuclear density gauges.

DOT National Transportation Integrated Search

2015-01-01

This report examines the possibility of replacing nuclear density gauges (NDGs) with non-nuclear density gauges (NNDGs) to : measure density of hot mix asphalt (HMA) and unbound pavement layers in the field. The research team evaluated the : effectiv...

A non-parametric automatic blending methodology to estimate rainfall fields from rain gauge and radar data

NASA Astrophysics Data System (ADS)

Velasco-Forero, Carlos A.; Sempere-Torres, Daniel; Cassiraga, Eduardo F.; Jaime Gómez-Hernández, J.

2009-07-01

Quantitative estimation of rainfall fields has been a crucial objective from early studies of the hydrological applications of weather radar. Previous studies have suggested that flow estimations are improved when radar and rain gauge data are combined to estimate input rainfall fields. This paper reports new research carried out in this field. Classical approaches for the selection and fitting of a theoretical correlogram (or semivariogram) model (needed to apply geostatistical estimators) are avoided in this study. Instead, a non-parametric technique based on FFT is used to obtain two-dimensional positive-definite correlograms directly from radar observations, dealing with both the natural anisotropy and the temporal variation of the spatial structure of the rainfall in the estimated fields. Because these correlation maps can be automatically obtained at each time step of a given rainfall event, this technique might easily be used in operational (real-time) applications. This paper describes the development of the non-parametric estimator exploiting the advantages of FFT for the automatic computation of correlograms and provides examples of its application on a case study using six rainfall events. This methodology is applied to three different alternatives to incorporate the radar information (as a secondary variable), and a comparison of performances is provided. In particular, their ability to reproduce in estimated rainfall fields (i) the rain gauge observations (in a cross-validation analysis) and (ii) the spatial patterns of radar fields are analyzed. Results seem to indicate that the methodology of kriging with external drift [KED], in combination with the technique of automatically computing 2-D spatial correlograms, provides merged rainfall fields with good agreement with rain gauges and with the most accurate approach to the spatial tendencies observed in the radar rainfall fields, when compared with other alternatives analyzed.

Discharge processes, electric field, and electron energy in ISUAL-recorded gigantic jets

NASA Astrophysics Data System (ADS)

Kuo, Cheng-Ling; Chou, J. K.; Tsai, L. Y.; Chen, A. B.; Su, H. T.; Hsu, R. R.; Cummer, S. A.; Frey, H. U.; Mende, S. B.; Takahashi, Y.; Lee, L. C.

2009-04-01

This article reports the first high time resolution measurements of gigantic jets from the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) experiment. The velocity of the upward propagating fully developed jet stage of the gigantic jets was ˜107 m s-1, which is similar to that observed for downward sprite streamers. Analysis of spectral ratios for the fully developed jet emissions gives a reduced E field of 400-655 Td and average electron energy of 8.5-12.3 eV. These values are higher than those in the sprites but are similar to those predicted by streamer models, which implies the existence of streamer tips in fully developed jets. The gigantic jets studied here all contained two distinct photometric peaks. The first peak is from the fully developed jet, which steadily propagates from the cloud top (˜20 km) to the lower ionosphere at ˜90 km. We suggest that the second photometric peak, which occurs ˜1 ms after the first peak, is from a current wave or potential wave-enhanced emissions that originate at an altitude of ˜50 km and extend toward the cloud top. We propose that the fully developed jet serves as an extension of the local ionosphere and produces a lowered ionosphere boundary. As the attachment processes remove the charges, the boundary of the local ionosphere moves up. The current in the channel persists and its contact point with the ionosphere moves upward, which produces the upward surging trailing jets. Imager and photometer data indicate that the lightning activity associated with the gigantic jets likely is in-cloud, and thus the initiation of the gigantic jets is not directly associated with cloud-to-ground discharges.

Gauge-free gyrokinetic theory

NASA Astrophysics Data System (ADS)

Burby, Joshua; Brizard, Alain

2017-10-01

Test-particle gyrocenter equations of motion play an essential role in the diagnosis of turbulent strongly-magnetized plasmas, and are playing an increasingly-important role in the formulation of kinetic-gyrokinetic hybrid models. Previous gyrocenter models required the knowledge of the perturbed electromagnetic potentials, which are not directly observable quantities (since they are gauge-dependent). A new gauge-free formulation of gyrocenter motion is presented, which enables gyrocenter trajectories to be determined using only measured values of the directly-observable electromagnetic field. Our gauge-free gyrokinetic theory is general enough to allow for gyroradius-scale fluctuations in both the electric and magnetic field. In addition, we provide gauge-free expressions for the charge and current densities produced by a distribution of gyrocenters, which explicitly include guiding-center and gyrocenter polarization and magnetization effects. This research was supported by the U.S. DOE Contract Nos. DE-SC0014032 (AB) and DE-AC05-06OR23100 (JB).

Flow field and scalar measurements in a series of turbulent partially-premixed dimethyl ether/air jet flames

DOE PAGES

Coriton, Bruno; Im, Seong -Kyun; Gamba, Mirko; ...

2017-03-12

Here, we present a series of benchmark flames consisting of six partially-premixed piloted dimethyl ether (DME)/air jet flames. These flames provide an opportunity to understand turbulence-flame interactions for oxygenated fuels and to develop predictive models for these interactions using a canonical burner geometry. The development of accurate models for DME/air flames would establish a foundation for studies of more complex oxygenated fuels. The flames are stabilized on a piloted jet burner similar to that of the partially-premixed methane/air jet flames that have been studied extensively within the context of the TNF Workshop. This series of six jet flames spans jetmore » exit Reynolds numbers, ReD, from 29,300 to 73,300 and stoichiometric mixture fractions, ξ st, from 0.35 to 0.60. Flame conditions range from very low probability of localized extinction to a high probability of localized extinction and subsequent re-ignition. Measurements in the flames are compared at downstream locations from 5 to 25 diameters above the nozzle exit. Mean and fluctuating velocity components are measured using stereo particle image velocimetry (SPIV). Simultaneous laser-induced fluorescence (LIF) imaging of OH and CH 2O provides insights into the distribution of these intermediate species in partially-premixed DME/air flames. OH LIF imaging is also combined with SPIV to investigate the strain rate field across the reaction zone.« less

Flow field and scalar measurements in a series of turbulent partially-premixed dimethyl ether/air jet flames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coriton, Bruno; Im, Seong -Kyun; Gamba, Mirko

Here, we present a series of benchmark flames consisting of six partially-premixed piloted dimethyl ether (DME)/air jet flames. These flames provide an opportunity to understand turbulence-flame interactions for oxygenated fuels and to develop predictive models for these interactions using a canonical burner geometry. The development of accurate models for DME/air flames would establish a foundation for studies of more complex oxygenated fuels. The flames are stabilized on a piloted jet burner similar to that of the partially-premixed methane/air jet flames that have been studied extensively within the context of the TNF Workshop. This series of six jet flames spans jetmore » exit Reynolds numbers, ReD, from 29,300 to 73,300 and stoichiometric mixture fractions, ξ st, from 0.35 to 0.60. Flame conditions range from very low probability of localized extinction to a high probability of localized extinction and subsequent re-ignition. Measurements in the flames are compared at downstream locations from 5 to 25 diameters above the nozzle exit. Mean and fluctuating velocity components are measured using stereo particle image velocimetry (SPIV). Simultaneous laser-induced fluorescence (LIF) imaging of OH and CH 2O provides insights into the distribution of these intermediate species in partially-premixed DME/air flames. OH LIF imaging is also combined with SPIV to investigate the strain rate field across the reaction zone.« less

The Invariant Twist of Magnetic Fields in the Relativistic Jets of Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Contopoulos, Ioannis; Christodoulou, Dimitris M.; Kazanas, Demosthenes; Gabuzda, Denise C.

2009-01-01

The origin of cosmic magnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of accretion disks in Active Galactic Nuclei (AGNs) by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with photons. While dynamo processes show no preference for the polarity of the (presumably random) seed field that they amplify, this alternative mechanism uniquely relates the polarity of the poloidal B field to the angular velocity of the accretion disk, resulting in a unique direction for the toroidal B field induced by disk rotation. Observations of the toroidal fields of 29 AGN jets revealed by parsec-scale Faraday rotation measurements show a clear asymmetry that is consistent with this model, with the probability that this asymmetry came about by chance being less than 1 %. This lends support to the hypothesis that the Universe is seeded by B fields that are generated in AGN via this mechanism

Mixing and unmixedness in plasma jets 1: Near-field analysis

NASA Technical Reports Server (NTRS)

Ilegbusi, Olusegun J.

1993-01-01

The flow characteristics in the near-field of a plasma jet are simulated with a two-fluid model. This model accounts for both gradient-diffusion mixing and uni-directional sifting motion resulting from pressure-gradient-body-force imbalance. This latter mechanism is believed to be responsible for the umixedness observed in plasma jets. The unmixedness is considered to be essentially a Rayleigh-Taylor kind instability. Transport equations are solved for the individual plasma and ambient gas velocities, temperatures and volume fractions. Empirical relations are employed for the interface transfers of mass, momentum and heat. The empirical coefficients are first established by comparison of predictions with available experimental data for shear flows. The model is then applied to an Argon plasma jet ejecting into stagnant air. The predicted results show the significant build-up of unmixed air within the plasma gas, even relatively far downstream of the torch. By adjusting the inlet condition, the model adequately reproduces the experimental data.

Program to stimulate graduate training in the field of aeroacoustics. [cross correlation of flow fields of a jet-blown flap with far fields

NASA Technical Reports Server (NTRS)

Becker, R. S.

1975-01-01

An experiment is reported to cross correlate the output of hot film probes located at various points in the flow field of a jet-blown flap with the output of microphones in the acoustic far field. Fluid dynamic measurements of the flow fields of the test configuration are reported.

Mast Cells Mediate the Immune Suppression Induced by Dermal Exposure to JP-8 Jet Fuel

PubMed Central

Limón-Flores, Alberto Y.; Chacón-Salinas, Rommel; Ramos, Gerardo; Ullrich, Stephen E.

2009-01-01

Applying jet propulsion-8 (JP-8) jet fuel to the skin of mice induces immune suppression. Applying JP-8 to the skin of mice suppresses T-cell–mediated immune reactions including, contact hypersensitivity (CHS) delayed-type hypersensitivity and T-cell proliferation. Because dermal mast cells play an important immune regulatory role in vivo, we tested the hypothesis that mast cells mediate jet fuel–induced immune suppression. When we applied JP-8 to the skin of mast cell deficient mice CHS was not suppressed. Reconstituting mast cell deficient mice with wild-type bone marrow derived mast cells (mast cell “knock-in mice”) restored JP-8–induced immune suppression. When, however, mast cells from prostaglandin E2 (PGE2)–deficient mice were used, the ability of JP-8 to suppress CHS was not restored, indicating that mast cell–derived PGE2 was activating immune suppression. Examining the density of mast cells in the skin and lymph nodes of JP-8-treated mice indicated that jet fuel treatment caused an initial increase in mast cell density in the skin, followed by increased numbers of mast cells in the subcutaneous space and then in draining lymph nodes. Applying JP-8 to the skin increased mast cell expression of CXCR4, and increased the expression of CXCL12 by draining lymph node cells. Because CXCL12 is a chemoattractant for CXCR4+ mast cells, we treated JP-8-treated mice with AMD3100, a CXCR4 antagonist. AMD3100 blocked the mobilization of mast cells to the draining lymph node and inhibited JP-8–induced immune suppression. Our findings demonstrate the importance of mast cells in mediating jet fuel–induced immune suppression. PMID:19726579

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun

1989-01-01

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear-free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to solve the nondimensional form of steady state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of above stated parameters on the condensation Nusselt and Stanton numbers which characterize the steady-state interface condensation process are investigated. Detailed analysis to gain a better understanding of the fundamentals of fluid mixing and interface condensation is performed.

Stretched Inertial Jets

NASA Astrophysics Data System (ADS)

Ghabache, Elisabeth; Antkowiak, Arnaud; Seon, Thomas; Villermaux, Emmanuel

2015-11-01

Liquid jets often arise as short-lived bursting liquid flows. Cavitation or impact-driven jets, bursting champagne bubbles, shaped-charge jets, ballistospores or drop-on-demand inkjet printing are a few examples where liquid jets are suddenly released. The trademark of all these discharge jets is the property of being stretched, due to the quenching injection. the present theoretical and experimental investigation, the structure of the jet flow field will be unraveled experimentally for a few emblematic occurrences of discharge jets. Though the injection markedly depends on each flow configuration, the jet velocity field will be shown to be systematically and rapidly attracted to the universal stretching flow z/t. The emergence of this inertial attractor actually only relies on simple kinematic ingredients, and as such is fairly generic. The universality of the jet velocity structure will be discussed.

Studies of the flow and turbulence fields in a turbulent pulsed jet flame using LES/PDF

NASA Astrophysics Data System (ADS)

Zhang, Pei; Masri, Assaad R.; Wang, Haifeng

2017-09-01

A turbulent piloted jet flame subject to a rapid velocity pulse in its fuel jet inflow is proposed as a new benchmark case for the study of turbulent combustion models. In this work, we perform modelling studies of this turbulent pulsed jet flame and focus on the predictions of its flow and turbulence fields. An advanced modelling strategy combining the large eddy simulation (LES) and the probability density function (PDF) methods is employed to model the turbulent pulsed jet flame. Characteristics of the velocity measurements are analysed to produce a time-dependent inflow condition that can be fed into the simulations. The effect of the uncertainty in the inflow turbulence intensity is investigated and is found to be very small. A method of specifying the inflow turbulence boundary condition for the simulations of the pulsed jet flame is assessed. The strategies for validating LES of statistically transient flames are discussed, and a new framework is developed consisting of different averaging strategies and a bootstrap method for constructing confidence intervals. Parametric studies are performed to examine the sensitivity of the predictions of the flow and turbulence fields to model and numerical parameters. A direct comparison of the predicted and measured time series of the axial velocity demonstrates a satisfactory prediction of the flow and turbulence fields of the pulsed jet flame by the employed modelling methods.

Second-order Boltzmann equation: gauge dependence and gauge invariance

NASA Astrophysics Data System (ADS)

Naruko, Atsushi; Pitrou, Cyril; Koyama, Kazuya; Sasaki, Misao

2013-08-01

In the context of cosmological perturbation theory, we derive the second-order Boltzmann equation describing the evolution of the distribution function of radiation without a specific gauge choice. The essential steps in deriving the Boltzmann equation are revisited and extended given this more general framework: (i) the polarization of light is incorporated in this formalism by using a tensor-valued distribution function; (ii) the importance of a choice of the tetrad field to define the local inertial frame in the description of the distribution function is emphasized; (iii) we perform a separation between temperature and spectral distortion, both for the intensity and polarization for the first time; (iv) the gauge dependence of all perturbed quantities that enter the Boltzmann equation is derived, and this enables us to check the correctness of the perturbed Boltzmann equation by explicitly showing its gauge-invariance for both intensity and polarization. We finally discuss several implications of the gauge dependence for the observed temperature.

Formation mechanism of shock-induced particle jetting.

PubMed

Xue, K; Sun, L; Bai, C

2016-08-01

The shock dissemination of granular rings or shells is characterized by the formation of coherent particle jets that have different dimensions from those associated with the constituent grains. In order to identify the mechanisms governing the formation of particle jets, we carry out the simulations of the shock dispersal of quasi-two-dimensional particle rings based on the discrete-element method. The evolution of the particle velocities and contact forces on the time scales ranging from microseconds to milliseconds reveals a two-stage development of particle jets before they are expelled from the outer surface. Much effort is made to understand the particle agglomeration around the inner surface that initiates the jet formation. The shock interaction with the innermost particle layers generates a heterogeneous network of force chains with clusters of strong contacts regularly spaced around the inner surface. Momentum alongside the stresses is primarily transmitted along the strong force chains. Therefore, the clustering of strong force chains renders the agglomeration of fast-moving particles connected by strong force chains. The fast-moving particle clusters subsequently evolve into the incipient particle jets. The following competition among the incipient jets that undergo unbalanced growth leads to substantial elimination of the minor jets and the significant multiplication of the major jets, the number of jets thus varying with time. Moreover, the number of jets is found to increase with the strength of the shock loading due to an increased number of jets surviving the retarding effect of major jets.

Methods of Contemporary Gauge Theory

NASA Astrophysics Data System (ADS)

Makeenko, Yuri

2002-08-01

Preface; Part I. Path Integrals: 1. Operator calculus; 2. Second quantization; 3. Quantum anomalies from path integral; 4. Instantons in quantum mechanics; Part II. Lattice Gauge Theories: 5. Observables in gauge theories; 6. Gauge fields on a lattice; 7. Lattice methods; 8. Fermions on a lattice; 9. Finite temperatures; Part III. 1/N Expansion: 10. O(N) vector models; 11. Multicolor QCD; 12. QCD in loop space; 13. Matrix models; Part IV. Reduced Models: 14. Eguchi-Kawai model; 15. Twisted reduced models; 16. Non-commutative gauge theories.

Methods of Contemporary Gauge Theory

NASA Astrophysics Data System (ADS)

Makeenko, Yuri

2005-11-01

Preface; Part I. Path Integrals: 1. Operator calculus; 2. Second quantization; 3. Quantum anomalies from path integral; 4. Instantons in quantum mechanics; Part II. Lattice Gauge Theories: 5. Observables in gauge theories; 6. Gauge fields on a lattice; 7. Lattice methods; 8. Fermions on a lattice; 9. Finite temperatures; Part III. 1/N Expansion: 10. O(N) vector models; 11. Multicolor QCD; 12. QCD in loop space; 13. Matrix models; Part IV. Reduced Models: 14. Eguchi-Kawai model; 15. Twisted reduced models; 16. Non-commutative gauge theories.

Higher spin conformal geometry in three dimensions and prepotentials for higher spin gauge fields

NASA Astrophysics Data System (ADS)

Henneaux, Marc; Hörtner, Sergio; Leonard, Amaury

2016-01-01

We study systematically the conformal geometry of higher spin bosonic gauge fields in three spacetime dimensions. We recall the definition of the Cotton tensor for higher spins and establish a number of its properties that turn out to be key in solving in terms of prepotentials the constraint equations of the Hamiltonian (3 + 1) formulation of four-dimensional higher spin gauge fields. The prepotentials are shown to exhibit higher spin conformal symmetry. Just as for spins 1 and 2, they provide a remarkably simple, manifestly duality invariant formulation of the theory. While the higher spin conformal geometry is developed for arbitrary bosonic spin, we explicitly perform the Hamiltonian analysis and derive the solution of the constraints only in the illustrative case of spin 3. In a separate publication, the Hamiltonian analysis in terms of prepotentials is extended to all bosonic higher spins using the conformal tools of this paper, and the same emergence of higher spin conformal symmetry is confirmed.

On the relationship between acoustic energy density flux near the jet axis and far field acoustic intensity

NASA Technical Reports Server (NTRS)

Maestrello, L.

1973-01-01

By measurement and analysis, the relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field intensity is considered. The physical quantity used is the gradient of the pressure evaluated on a geometrical plane at the smallest possible radial distance from the jet axis, but outside the vortical region, in the area where the homogeneous wave equation is reasonably well satisfied. The numerical and experimental procedures involved have been checked out by using a known source. Results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number.

Directionally Aligned Amorphous Polymer Chains via Electrohydrodynamic-Jet Printing: Analysis of Morphology and Polymer Field-Effect Transistor Characteristics.

PubMed

Kim, Yebyeol; Bae, Jaehyun; Song, Hyun Woo; An, Tae Kyu; Kim, Se Hyun; Kim, Yun-Hi; Park, Chan Eon

2017-11-15

Electrohydrodynamic-jet (EHD-jet) printing provides an opportunity to directly assembled amorphous polymer chains in the printed pattern. Herein, an EHD-jet printed amorphous polymer was employed as the active layer for fabrication of organic field-effect transistors (OFETs). Under optimized conditions, the field-effect mobility (μ FET ) of the EHD-jet printed OFETs was 5 times higher than the highest μ FET observed in the spin-coated OFETs, and this improvement was achieved without the use of complex surface templating or additional pre- or post-deposition processing. As the chain alignment can be affected by the surface energy of the dielectric layer in EHD-jet printed OFETs, dielectric layers with varying wettability were examined. Near-edge X-ray absorption fine structure measurements were performed to compare the amorphous chain alignment in OFET active layers prepared by EHD-jet printing and spin coating.

Effective field theory analysis on μ problem in low-scale gauge mediation

NASA Astrophysics Data System (ADS)

Zheng, Sibo

2012-02-01

Supersymmetric models based on the scenario of gauge mediation often suffer from the well-known μ problem. In this paper, we reconsider this problem in low-scale gauge mediation in terms of effective field theory analysis. In this paradigm, all high energy input soft mass can be expressed via loop expansions. If the corrections coming from messenger thresholds are small, as we assume in this letter, then all RG evaluations can be taken as linearly approximation for low-scale supersymmetric breaking. Due to these observations, the parameter space can be systematically classified and studied after constraints coming from electro-weak symmetry breaking are imposed. We find that some old proposals in the literature are reproduced, and two new classes are uncovered. We refer to a microscopic model, where the specific relations among coefficients in one of the new classes are well motivated. Also, we discuss some primary phenomenologies.

Rectangular subsonic jet flow field measurements

NASA Technical Reports Server (NTRS)

Morrison, Gerald L.; Swan, David H.

1989-01-01

Flow field measurements are presented of 3 subsonic rectangular cold air jets. The 3 cases presented had aspect ratios of 1 x 2, 1 x 4 at a Mach number of 0.09 and an aspect ratio of 1 x 2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemoneter system. The presented data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data is presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made. All tabular data are available in ASCII format on MS-DOS compatible disks.

Radiatively induced neutrino mass model with flavor dependent gauge symmetry

NASA Astrophysics Data System (ADS)

Lee, SangJong; Nomura, Takaaki; Okada, Hiroshi

2018-06-01

We study a radiative seesaw model at one-loop level with a flavor dependent gauge symmetry U(1) μ - τ, in which we consider bosonic dark matter. We also analyze the constraints from lepton flavor violations, muon g - 2, relic density of dark matter, and collider physics, and carry out numerical analysis to search for allowed parameter region which satisfy all the constraints and to investigate some predictions. Furthermore we find that a simple but adhoc hypothesis induces specific two zero texture with inverse mass matrix, which provides us several predictions such as a specific pattern of Dirac CP phase.

Control of jet noise

NASA Technical Reports Server (NTRS)

Schreck, Stefan

1992-01-01

To investigate the possibility of active control of jet noise, knowledge of the noise generation mechanisms in natural jets is essential. Once these mechanisms are determined, active control can be used to manipulate the noise production processes. We investigated the evolution of the flow fields and the acoustic fields of rectangular and circular jets. A predominant flapping mode was found in the supersonic rectangular jets. We hope to increase the spreading of supersonic jets by active control of the flapping mode found in rectangular supersonic jets.

Probing stochastic inter-galactic magnetic fields using blazar-induced gamma ray halo morphology

NASA Astrophysics Data System (ADS)

Duplessis, Francis; Vachaspati, Tanmay

2017-05-01

Inter-galactic magnetic fields can imprint their structure on the morphology of blazar-induced gamma ray halos. We show that the halo morphology arises through the interplay of the source's jet and a two-dimensional surface dictated by the magnetic field. Through extensive numerical simulations, we generate mock halos created by stochastic magnetic fields with and without helicity, and study the dependence of the halo features on the properties of the magnetic field. We propose a sharper version of the Q-statistics and demonstrate its sensitivity to the magnetic field strength, the coherence scale, and the handedness of the helicity. We also identify and explain a new feature of the Q-statistics that can further enhance its power.

Improving LHC searches for dark photons using lepton-jet substructure

NASA Astrophysics Data System (ADS)

Barello, G.; Chang, Spencer; Newby, Christopher A.; Ostdiek, Bryan

2017-03-01

Collider signals of dark photons are an exciting probe for new gauge forces and are characterized by events with boosted lepton jets. Existing techniques are efficient in searching for muonic lepton jets but due to substantial backgrounds have difficulty constraining lepton jets containing only electrons. This is unfortunate since upcoming intensity frontier experiments are sensitive to dark photon masses which only allow electron decays. Analyzing a recently proposed model of kinetic mixing, with new scalar particles decaying into dark photons, we find that existing techniques for electron jets can be substantially improved. We show that using lepton-jet-substructure variables, in association with a boosted decision tree, improves background rejection, significantly increasing the LHC's reach for dark photons in this region of parameter space.

Gauge Theory on a Space with Linear Lie Type Fuzziness

NASA Astrophysics Data System (ADS)

Khorrami, Mohammad; Fatollahi, Amir H.; Shariati, Ahmad

2013-03-01

The U(1) gauge theory on a space with Lie type noncommutativity is constructed. The construction is based on the group of translations in Fourier space, which in contrast to space itself is commutative. In analogy with lattice gauge theory, the object playing the role of flux of field strength per plaquette, as well as the action, is constructed. It is observed that the theory, in comparison with ordinary U(1) gauge theory, has an extra gauge field component. This phenomena is reminiscent of similar ones in formulation of SU(N) gauge theory in space with canonical noncommutativity, and also appearance of gauge field component in discrete direction of Connes' construction of the Standard Model.

Self-induced quasistationary magnetic fields.

PubMed

Kamenetskii, E O

2006-01-01

The interaction of electromagnetic radiation with temporally dispersive magnetic solids of small dimensions may show very special resonant behaviors. The internal fields of such samples are characterized by magnetostatic-potential scalar wave functions. The oscillating modes have the energy orthogonality properties and unusual pseudoelectric (gauge) fields. Because of a phase factor, that makes the states single valued, a persistent magnetic current exists. This leads to appearance of an eigenelectric moment of a small disk sample. One of the intriguing features of the mode fields is dynamical symmetry breaking.

Antisymplectic gauge theories

NASA Astrophysics Data System (ADS)

Batalin, Igor; Marnelius, Robert

1998-02-01

A general field-antifield BV formalism for antisymplectic first class constraints is proposed. It is as general as the corresponding symplectic BFV-BRST formulation and it is demonstrated to be consistent with a previously proposed formalism for antisymplectic second class constraints through a generalized conversion to corresponding first class constraints. Thereby the basic concept of gauge symmetry is extended to apply to quite a new class of gauge theories potentially possible to exist.

Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets

NASA Technical Reports Server (NTRS)

Moore, R. L.; Cirtain, J. W.; Sterling, A. C.; Falconer, D. A.

2010-01-01

By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T 10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Event-by-event picture for the medium-induced jet evolution

NASA Astrophysics Data System (ADS)

Escobedo, Miguel A.; Iancu, Edmond

2017-08-01

We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-by-event picture of the gluon distribution produced via medium-induced gluon branching. In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on [1, 2].

Event-by-event picture for the medium-induced jet evolution

NASA Astrophysics Data System (ADS)

Escobedo, Miguel A.; Iancu, Edmond

2017-03-01

We discuss the evolution of an energetic jet which propagates through a dense quark-gluon plasma and radiates gluons due to its interactions with the medium. Within perturbative QCD, this evolution can be described as a stochastic branching process, that we have managed to solve exactly. We present exact, analytic, results for the gluon spectrum (the average gluon distribution) and for the higher n-point functions, which describe correlations and fluctuations. Using these results, we construct the event-by-event picture of the gluon distribution produced via medium-induced gluon branching. In contrast to what happens in a usual QCD cascade in vacuum, the medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent parton. We find large fluctuations in the energy loss and in the multiplicity of soft gluons. The multiplicity distribution is predicted to exhibit KNO (Koba-Nielsen-Olesen) scaling. These predictions can be tested in Pb+Pb collisions at the LHC, via event-by-event measurements of the di-jet asymmetry. Based on [1, 2].

Emergent gauge theories and supersymmetry: A QED primer

NASA Astrophysics Data System (ADS)

Chkareuli, J. L.

2013-04-01

We argue that a generic trigger for photon and other gauge fields to emerge as massless Nambu-Goldstone modes could be spontaneously broken supersymmetry rather than physically manifested Lorentz violation. We consider supersymmetric QED model extended by an arbitrary polynomial potential of vector superfield that induces the spontaneous SUSY violation in the visible sector. As a consequence, massless photon appears as a companion of massless photino being Goldstone fermion state in tree approximation. Remarkably, the photon masslessness appearing at tree level is further protected against radiative corrections due to the simultaneously generated special gauge invariance in the broken SUSY phase. Meanwhile, photino being mixed with another goldstino appearing from a spontaneous SUSY violation in the hidden sector largely turns into light pseudo-goldstino whose physics seems to be of special interest.

Extending acoustic data measured with small-scale supersonic model jets to practical aircraft exhaust jets

NASA Astrophysics Data System (ADS)

Kuo, Ching-Wen

2010-06-01

Modern military aircraft jet engines are designed with variable geometry nozzles to provide optimum thrust in different operating conditions within the flight envelope. However, the acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometry of these nozzles. Thus the present effort at The Pennsylvania State University and the NASA Glenn Research Center, in partnership with GE Aviation, is aiming to study and characterize the acoustic field produced by supersonic jets issuing from converging-diverging military style nozzles. An equally important objective is to develop a scaling methodology for using data obtained from small- and moderate-scale experiments which exhibits the independence of the jet sizes to the measured noise levels. The experimental results presented in this thesis have shown reasonable agreement between small-scale and moderate-scale jet acoustic data, as well as between heated jets and heat-simulated ones. As the scaling methodology is validated, it will be extended to using acoustic data measured with small-scale supersonic model jets to the prediction of the most important components of full-scale engine noise. When comparing the measured acoustic spectra with a microphone array set at different radial locations, the characteristics of the jet noise source distribution may induce subtle inaccuracies, depending on the conditions of jet operation. A close look is taken at the details of the noise generation region in order to better understand the mismatch between spectra measured at various acoustic field radial locations. A processing methodology was developed to correct the effect of the noise source distribution and efficiently compare near-field and far-field spectra with unprecedented accuracy. This technique then demonstrates that the measured noise levels in the physically restricted space of an anechoic chamber can be appropriately

Jet angularity measurements for single inclusive jet production

NASA Astrophysics Data System (ADS)

Kang, Zhong-Bo; Lee, Kyle; Ringer, Felix

2018-04-01

We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in- and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

Feynman rules for the Standard Model Effective Field Theory in R ξ -gauges

NASA Astrophysics Data System (ADS)

Dedes, A.; Materkowska, W.; Paraskevas, M.; Rosiek, J.; Suxho, K.

2017-06-01

We assume that New Physics effects are parametrized within the Standard Model Effective Field Theory (SMEFT) written in a complete basis of gauge invariant operators up to dimension 6, commonly referred to as "Warsaw basis". We discuss all steps necessary to obtain a consistent transition to the spontaneously broken theory and several other important aspects, including the BRST-invariance of the SMEFT action for linear R ξ -gauges. The final theory is expressed in a basis characterized by SM-like propagators for all physical and unphysical fields. The effect of the non-renormalizable operators appears explicitly in triple or higher multiplicity vertices. In this mass basis we derive the complete set of Feynman rules, without resorting to any simplifying assumptions such as baryon-, lepton-number or CP conservation. As it turns out, for most SMEFT vertices the expressions are reasonably short, with a noticeable exception of those involving 4, 5 and 6 gluons. We have also supplemented our set of Feynman rules, given in an appendix here, with a publicly available Mathematica code working with the FeynRules package and producing output which can be integrated with other symbolic algebra or numerical codes for automatic SMEFT amplitude calculations.

A Student-Centered Field Project Comparing NEXRAD and Rain Gauge Precipitation Values in Mountainous Terrain.

ERIC Educational Resources Information Center

Woltemade, Christopher J.; Stanitski-Martin, Diane

2002-01-01

Undergraduate students compared Next Generation Weather Radar (NEXRAD) estimates of storm total precipitation to measurements from a network of 20 rain gauges. Student researchers gained valuable experience in field data collection, global positioning systems (GPS), geographic information systems (GIS), Internet data access and downloading,…

Dual gauge field theory of quantum liquid crystals in two dimensions

NASA Astrophysics Data System (ADS)

Beekman, Aron J.; Nissinen, Jaakko; Wu, Kai; Liu, Ke; Slager, Robert-Jan; Nussinov, Zohar; Cvetkovic, Vladimir; Zaanen, Jan

2017-04-01

We present a self-contained review of the theory of dislocation-mediated quantum melting at zero temperature in two spatial dimensions. The theory describes the liquid-crystalline phases with spatial symmetries in between a quantum crystalline solid and an isotropic superfluid: quantum nematics and smectics. It is based on an Abelian-Higgs-type duality mapping of phonons onto gauge bosons (;stress photons;), which encode for the capacity of the crystal to propagate stresses. Dislocations and disclinations, the topological defects of the crystal, are sources for the gauge fields and the melting of the crystal can be understood as the proliferation (condensation) of these defects, giving rise to the Anderson-Higgs mechanism on the dual side. For the liquid crystal phases, the shear sector of the gauge bosons becomes massive signaling that shear rigidity is lost. After providing the necessary background knowledge, including the order parameter theory of two-dimensional quantum liquid crystals and the dual theory of stress gauge bosons in bosonic crystals, the theory of melting is developed step-by-step via the disorder theory of dislocation-mediated melting. Resting on symmetry principles, we derive the phenomenological imaginary time actions of quantum nematics and smectics and analyze the full spectrum of collective modes. The quantum nematic is a superfluid having a true rotational Goldstone mode due to rotational symmetry breaking, and the origin of this 'deconfined' mode is traced back to the crystalline phase. The two-dimensional quantum smectic turns out to be a dizzyingly anisotropic phase with the collective modes interpolating between the solid and nematic in a non-trivial way. We also consider electrically charged bosonic crystals and liquid crystals, and carefully analyze the electromagnetic response of the quantum liquid crystal phases. In particular, the quantum nematic is a real superconductor and shows the Meissner effect. Their special properties

Dual gauge field theory of quantum liquid crystals in two dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beekman, Aron J.; Nissinen, Jaakko; Wu, Kai

We present a self-contained review of the theory of dislocation-mediated quantum melting at zero temperature in two spatial dimensions. The theory describes the liquid-crystalline phases with spatial symmetries in between a quantum crystalline solid and an isotropic superfluid: quantum nematics and smectics. It is based on an Abelian-Higgs-type duality mapping of phonons onto gauge bosons (“stress photons”), which encode for the capacity of the crystal to propagate stresses. Dislocations and disclinations, the topological defects of the crystal, are sources for the gauge fields and the melting of the crystal can be understood as the proliferation (condensation) of these defects, givingmore » rise to the Anderson–Higgs mechanism on the dual side. For the liquid crystal phases, the shear sector of the gauge bosons becomes massive signaling that shear rigidity is lost. After providing the necessary background knowledge, including the order parameter theory of two-dimensional quantum liquid crystals and the dual theory of stress gauge bosons in bosonic crystals, the theory of melting is developed step-by-step via the disorder theory of dislocation-mediated melting. Resting on symmetry principles, we derive the phenomenological imaginary time actions of quantum nematics and smectics and analyze the full spectrum of collective modes. The quantum nematic is a superfluid having a true rotational Goldstone mode due to rotational symmetry breaking, and the origin of this ‘deconfined’ mode is traced back to the crystalline phase. The two-dimensional quantum smectic turns out to be a dizzyingly anisotropic phase with the collective modes interpolating between the solid and nematic in a non-trivial way. We also consider electrically charged bosonic crystals and liquid crystals, and carefully analyze the electromagnetic response of the quantum liquid crystal phases. In particular, the quantum nematic is a real superconductor and shows the Meissner effect. Furthermore

Dual gauge field theory of quantum liquid crystals in two dimensions

DOE PAGES

Beekman, Aron J.; Nissinen, Jaakko; Wu, Kai; ...

2017-04-18

We present a self-contained review of the theory of dislocation-mediated quantum melting at zero temperature in two spatial dimensions. The theory describes the liquid-crystalline phases with spatial symmetries in between a quantum crystalline solid and an isotropic superfluid: quantum nematics and smectics. It is based on an Abelian-Higgs-type duality mapping of phonons onto gauge bosons (“stress photons”), which encode for the capacity of the crystal to propagate stresses. Dislocations and disclinations, the topological defects of the crystal, are sources for the gauge fields and the melting of the crystal can be understood as the proliferation (condensation) of these defects, givingmore » rise to the Anderson–Higgs mechanism on the dual side. For the liquid crystal phases, the shear sector of the gauge bosons becomes massive signaling that shear rigidity is lost. After providing the necessary background knowledge, including the order parameter theory of two-dimensional quantum liquid crystals and the dual theory of stress gauge bosons in bosonic crystals, the theory of melting is developed step-by-step via the disorder theory of dislocation-mediated melting. Resting on symmetry principles, we derive the phenomenological imaginary time actions of quantum nematics and smectics and analyze the full spectrum of collective modes. The quantum nematic is a superfluid having a true rotational Goldstone mode due to rotational symmetry breaking, and the origin of this ‘deconfined’ mode is traced back to the crystalline phase. The two-dimensional quantum smectic turns out to be a dizzyingly anisotropic phase with the collective modes interpolating between the solid and nematic in a non-trivial way. We also consider electrically charged bosonic crystals and liquid crystals, and carefully analyze the electromagnetic response of the quantum liquid crystal phases. In particular, the quantum nematic is a real superconductor and shows the Meissner effect. Furthermore

SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ilgenfritz, Ernst-Michael; Humboldt-Universitaet zu Berlin, Institut fuer Physik, 12489 Berlin; Menz, Christoph

2011-03-01

We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of themore » associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory.« less

Supersonic laser-induced jetting of aluminum micro-droplets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zenou, M.; Additive Manufacturing Lab, Orbotech Ltd., P.O. Box 215, 81101 Yavne; Sa'ar, A.

The droplet velocity and the incubation time of pure aluminum micro-droplets, printed using the method of sub-nanosecond laser induced forward transfer, have been measured indicating the formation of supersonic laser-induced jetting. The incubation time and the droplet velocity were extracted by measuring a transient electrical signal associated with droplet landing on the surface of the acceptor substrate. This technique has been exploited for studying small volume droplets, in the range of 10–100 femto-litters for which supersonic velocities were measured. The results suggest elastic propagation of the droplets across the donor-to-acceptor gap, a nonlinear deposition dynamics on the surface of themore » acceptor and overall efficient energy transfer from the laser beam to the droplets.« less

Twin Jet Effects on Noise of Round and Rectangular Jets: Experiment and Model

NASA Technical Reports Server (NTRS)

Bozak, Rick

2014-01-01

Many subsonic and supersonic aircraft concepts proposed by NASA's Fundamental Aeronautics Program have asymmetric, integrated propulsion systems. The asymmetries in the exhaust of these propulsion systems create an asymmetric acoustic field. The asymmetries investigated in the current study are from twin jets and rectangular nozzles. Each effect produces its own variation of the acoustic field. An empirical model was developed to predict the acoustic field variation from round twin jets with twin jet spacing from 2.6 to 5.6, where s is the center-to-center spacing over the jet diameter. The model includes parameters to account for the effects of twin jet spacing, jet static temperature ratio, flight Mach number, frequency, and observer angle (both polar and azimuthal angles). The model was then applied to twin 2:1 and 8:1 aspect ratio nozzles to determine the impact of jet aspect ratio. For the round and rectangular jets, the use of the model reduces the average magnitude of the error over all frequencies, observation angles, and jet spacings by approximately 0.5dB when compared against the assumption of adding two jets incoherently.

Effects of jet-induced medium excitation in γ-hadron correlation in A+A collisions

NASA Astrophysics Data System (ADS)

Chen, Wei; Cao, Shanshan; Luo, Tan; Pang, Long-Gang; Wang, Xin-Nian

2018-02-01

Coupled Linear Boltzmann Transport and hydrodynamics (CoLBT-hydro) is developed for co-current and event-by-event simulations of jet transport and jet-induced medium excitation (j.i.m.e.) in high-energy heavy-ion collisions. This is made possible by a GPU parallelized (3 + 1)D hydrodynamics that has a source term from the energy-momentum deposition by propagating jet shower partons and provides real time update of the bulk medium evolution for subsequent jet transport. Hadron spectra in γ-jet events of A+A collisions at RHIC and LHC are calculated for the first time that include hadrons from both the modified jet and j.i.m.e. CoLBT-hydro describes well experimental data at RHIC on the suppression of leading hadrons due to parton energy loss. It also predicts the enhancement of soft hadrons from j.i.m.e. The onset of soft hadron enhancement occurs at a constant transverse momentum due to the thermal nature of soft hadrons from j.i.m.e. which also have a significantly broadened azimuthal distribution relative to the jet direction. Soft hadrons in the γ direction are, on the other hand, depleted due to a diffusion wake behind the jet.

Effects of jet-induced medium excitation in γ-hadron correlation in A+A collisions

DOE PAGES

Chen, Wei; Cao, Shanshan; Luo, Tan; ...

2017-12-07

Coupled Linear Boltzmann Transport and hydrodynamics (CoLBT-hydro) is developed for co-current and event-by-event simulations of jet transport and jet-induced medium excitation (j.i.m.e.) in high-energy heavy-ion collisions. This is made possible by a GPU parallelized (3+1)D hydrodynamics that has a source term from the energy-momentum deposition by propagating jet shower partons and provides real time update of the bulk medium evolution for subsequent jet transport. Hadron spectra in γ-jet events of A+A collisions at RHIC and LHC are calculated for the first time that include hadrons from both the modified jet and j.i.m.e. CoLBT-hydro describes well experimental data at RHIC onmore » the suppression of leading hadrons due to parton energy loss. It also predicts the enhancement of soft hadrons from j.i.m.e. The onset of soft hadron enhancement occurs at a constant transverse momentum due to the thermal nature of soft hadrons from j.i.m.e. which also have a significantly broadened azimuthal distribution relative to the jet direction. Soft hadrons in the γ direction are, on the other hand, depleted due to a diffusion wake behind the jet.« less

Effects of jet-induced medium excitation in γ-hadron correlation in A+A collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Wei; Cao, Shanshan; Luo, Tan

Coupled Linear Boltzmann Transport and hydrodynamics (CoLBT-hydro) is developed for co-current and event-by-event simulations of jet transport and jet-induced medium excitation (j.i.m.e.) in high-energy heavy-ion collisions. This is made possible by a GPU parallelized (3+1)D hydrodynamics that has a source term from the energy-momentum deposition by propagating jet shower partons and provides real time update of the bulk medium evolution for subsequent jet transport. Hadron spectra in γ-jet events of A+A collisions at RHIC and LHC are calculated for the first time that include hadrons from both the modified jet and j.i.m.e. CoLBT-hydro describes well experimental data at RHIC onmore » the suppression of leading hadrons due to parton energy loss. It also predicts the enhancement of soft hadrons from j.i.m.e. The onset of soft hadron enhancement occurs at a constant transverse momentum due to the thermal nature of soft hadrons from j.i.m.e. which also have a significantly broadened azimuthal distribution relative to the jet direction. Soft hadrons in the γ direction are, on the other hand, depleted due to a diffusion wake behind the jet.« less

Static and wind tunnel near-field/far field jet noise measurements from model scale single-flow baseline and suppressor nozzles. Volume 2: Forward speed effects

NASA Technical Reports Server (NTRS)

Jaeck, C. L.

1976-01-01

A model scale flight effects test was conducted in the 40 by 80 foot wind tunnel to investigate the effect of aircraft forward speed on single flow jet noise characteristics. The models tested included a 15.24 cm baseline round convergent nozzle, a 20-lobe and annular nozzle with and without lined ejector shroud, and a 57-tube nozzle with a lined ejector shroud. Nozzle operating conditions covered jet velocities from 412 to 640 m/s at a total temperature of 844 K. Wind tunnel speeds were varied from near zero to 91.5 m/s. Measurements were analyzed to (1) determine apparent jet noise source location including effects of ambient velocity; (2) verify a technique for extrapolating near field jet noise measurements into the far field; (3) determine flight effects in the near and far field for baseline and suppressor nozzles; and (4) establish the wind tunnel as a means of accurately defining flight effects for model nozzles and full scale engines.

Radio Emission from Three-dimensional Relativistic Hydrodynamic Jets: Observational Evidence of Jet Stratification

NASA Astrophysics Data System (ADS)

Aloy, Miguel-Angel; Gómez, José-Luis; Ibáñez, José-María; Martí, José-María; Müller, Ewald

2000-01-01

We present the first radio emission simulations from high-resolution three-dimensional relativistic hydrodynamic jets; these simulations allow us to study the observational implications of the interaction between the jet and the external medium. This interaction gives rise to a stratification of the jet in which a fast spine is surrounded by a slow high-energy shear layer. The stratification (in particular, the large specific internal energy and slow flow in the shear layer) largely determines the emission from the jet. If the magnetic field in the shear layer becomes helical (e.g., resulting from an initial toroidal field and an aligned field component generated by shear), the emission shows a cross section asymmetry, in which either the top or the bottom of the jet dominates the emission. This, as well as limb or spine brightening, is a function of the viewing angle and flow velocity, and the top/bottom jet emission predominance can be reversed if the jet changes direction with respect to the observer or if it presents a change in velocity. The asymmetry is more prominent in the polarized flux because of field cancellation (or amplification) along the line of sight. Recent observations of jet cross section emission asymmetries in the blazar 1055+018 can be explained by assuming the existence of a shear layer with a helical magnetic field.

Atomic quantum simulation of the lattice gauge-Higgs model: Higgs couplings and emergence of exact local gauge symmetry.

PubMed

Kasamatsu, Kenichi; Ichinose, Ikuo; Matsui, Tetsuo

2013-09-13

Recently, the possibility of quantum simulation of dynamical gauge fields was pointed out by using a system of cold atoms trapped on each link in an optical lattice. However, to implement exact local gauge invariance, fine-tuning the interaction parameters among atoms is necessary. In the present Letter, we study the effect of violation of the U(1) local gauge invariance by relaxing the fine-tuning of the parameters and showing that a wide variety of cold atoms is still a faithful quantum simulator for a U(1) gauge-Higgs model containing a Higgs field sitting on sites. The clarification of the dynamics of this gauge-Higgs model sheds some light upon various unsolved problems, including the inflation process of the early Universe. We study the phase structure of this model by Monte Carlo simulation and also discuss the atomic characteristics of the Higgs phase in each simulator.

Three-dimensional particle-in-cell simulations of a plasma jet/cloud streaming across a transverse magnetic field

NASA Astrophysics Data System (ADS)

Voitcu, Gabriel; Echim, Marius

2014-05-01

The dynamics of collisionless plasma jets/clouds in magnetic field configurations typical for the terrestrial magnetotail and frontside magnetosheath is a topic of interest for understanding the physics of the magnetosphere and its interaction with the solar wind. The presence of high-speed jets in the frontside magnetosheath has been recently proved experimentally by Cluster and THEMIS spacecrafts. There is increasing evidence that the bursty bulk flows in the magnetotail have jet-like features. In the present paper we use fully electromagnetic 3D explicit particle-in-cell (PIC) simulations to investigate the interaction of a localized three-dimensional plasma element/jet/cloud with a transverse magnetic field. We consider a plasma jet/cloud that moves in vacuum and perpendicular to an ambient magnetic field. Ampère and Faraday's laws are used to compute the self-consistent electric and magnetic fields on a three-dimensional spatial grid having a step-size of the order of the Debye length and using a time-step that resolves the plasma frequency. The initial magnetic field inside the simulation domain is uniform and the plasma bulk velocity at the beginning of the simulation is normal to the magnetic field direction. The total time scale of the simulation is of the order of few ion Larmor periods. Space and time variations of the plasma parameters and of the electromagnetic field are analyzed and discussed. We emphasize non-MHD effects like the energy-dispersion signatures at the edges of the plasma element, similar to results previously reported by Voitcu and Echim (2012) using test-kinetic simulations. Acknowledgments: Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

Gauge supergravity in D = 2 + 2

NASA Astrophysics Data System (ADS)

Castellani, Leonardo

2017-10-01

We present an action for chiral N = (1 , 0) supergravity in 2 + 2 dimensions. The fields of the theory are organized into an OSp(1|4) connection supermatrix, and are given by the usual vierbein V a , spin connection ω ab , and Majorana gravitino ψ. In analogy with a construction used for D = 10 + 2 gauge supergravity, the action is given by ∫STr( R 2 Γ), where R is the OSp(1|4) curvature supermatrix two-form, and Γ a constant supermatrix containing γ 5. It is similar, but not identical to the MacDowell-Mansouri action for D = 2 + 2 supergravity. The constant supermatrix breaks OSp(1|4) gauge invariance to a subalgebra OSp(1|2) ⊕ Sp(2), including a Majorana-Weyl supercharge. Thus half of the OSp(1|4) gauge supersymmetry survives. The gauge fields are the selfdual part of ω ab and the Weyl projection of ψ for OSp(1|2), and the antiselfdual part of ω ab for Sp(2). Supersymmetry transformations, being part of a gauge superalgebra, close off-shell. The selfduality condition on the spin connection can be consistently imposed, and the resulting "projected" action is OSp(1|2) gauge invariant.

Neutrino jets from high-mass WR gauge bosons in TeV-scale left-right symmetric models

NASA Astrophysics Data System (ADS)

Mitra, Manimala; Ruiz, Richard; Scott, Darren J.; Spannowsky, Michael

2016-11-01

We reexamine the discovery potential at hadron colliders of high-mass right-handed (RH) gauge bosons WR—an inherent ingredient of left-right symmetric models (LRSM). We focus on the regime where the WR is very heavy compared to the heavy Majorana neutrino N , and we investigate an alternative signature for WR→N decays. The produced neutrinos are highly boosted in this mass regime. Subsequently, their decays via off-shell WR bosons to jets, i.e., N →ℓ±jj, are highly collimated, forming a single neutrino jet (jN). The final-state collider signature is then ℓ±jN, instead of the widely studied ℓ±ℓ±j j . Present search strategies are not sensitive to this hierarchical mass regime due to the breakdown of the collider signature definition. We take into account QCD corrections beyond next-to-leading order (NLO) that are important for high-mass Drell-Yan processes at the 13 TeV Large Hadron Collider (LHC). For the first time, we evaluate WR production at NLO with threshold resummation at next-to-next-to-leading logarithm (NNLL) matched to the threshold-improved parton distributions. With these improvements, we find that a WR of mass MWR=3 (4 )[5 ] TeV and mass ratio of (mN/MWR)<0.1 can be discovered with a 5 - 6 σ statistical significance at 13 TeV after 10 (100 )[2000 ] fb-1 of data. Extending the analysis to the hypothetical 100 TeV Very Large Hadron Collider (VLHC), 5 σ can be obtained for WR masses up to MW R=15 (30 ) with approximately 100 fb-1 (10 ab-1 ). Conversely, with 0.9 (10 )[150 ] fb-1 of 13 TeV data, MWR<3 (4 )[5 ] TeV and (mN/MWR)<0.1 can be excluded at 95% C.L.; with 100 fb-1 (2.5 ab-1 ) of 100 TeV data, MW R<22 (33 ) TeV can be excluded.

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

2010-09-01

By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jetsmore » that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.« less

Non-Abelian gauge preheating

NASA Astrophysics Data System (ADS)

Adshead, Peter; Giblin, John T.; Weiner, Zachary J.

2017-12-01

We study preheating in models where a scalar inflaton is directly coupled to a non-Abelian S U (2 ) gauge field. In particular, we examine m2ϕ2 inflation with a conformal, dilatonlike coupling to the non-Abelian sector. We describe a numerical scheme that combines lattice gauge theory with standard finite difference methods applied to the scalar field. We show that a significant tachyonic instability allows for efficient preheating, which is parametrically suppressed by increasing the non-Abelian self-coupling. Additionally, we comment on the technical implementation of the evolution scheme and setting initial conditions.

Jet-induced star formation in 3C 285 and Minkowski's Object

NASA Astrophysics Data System (ADS)

Salomé, Q.; Salomé, P.; Combes, F.

2015-02-01

How efficiently star formation proceeds in galaxies is still an open question. Recent studies suggest that active galactic nucleus (AGN) can regulate the gas accretion and thus slow down star formation (negative feedback). However, evidence of AGN positive feedback has also been observed in a few radio galaxies (e.g. Centaurus A, Minkowski's Object, 3C 285, and the higher redshift 4C 41.17). Here we present CO observations of 3C 285 and Minkowski's Object, which are examples of jet-induced star formation. A spot (named 3C 285/09.6 in the present paper) aligned with the 3C 285 radio jet at a projected distance of ~70 kpc from the galaxy centre shows star formation that is detected in optical emission. Minkowski's Object is located along the jet of NGC 541 and also shows star formation. Knowing the distribution of molecular gas along the jets is a way to study the physical processes at play in the AGN interaction with the intergalactic medium. We observed CO lines in 3C 285, NGC 541, 3C 285/09.6, and Minkowski's Object with the IRAM 30 m telescope. In the central galaxies, the spectra present a double-horn profile, typical of a rotation pattern, from which we are able to estimate the molecular gas density profile of the galaxy. The molecular gas appears to be in a compact reservoir, which could be evidence of an early phase of the gas accretion after a recent merger event in 3C 285. No kinematic signature of a molecular outflow is detected by the 30 m telescope. Interestingly, 3C 285/09.6 and Minkowski's Object are not detected in CO. The cold gas mass upper limits are consistent with a star formation induced by the compression of dense ambient material by the jet. The depletion time scales in 3C 285/09.6 and Minkowski's Object are of the order of and even shorter than what is found in 3C 285, NGC 541, and local spiral galaxies (109 yr). The upper limit of the molecular gas surface density in 3C 285/09.6 at least follows a Schmidt-Kennicutt law if the emitting region

Probing stochastic inter-galactic magnetic fields using blazar-induced gamma ray halo morphology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duplessis, Francis; Vachaspati, Tanmay, E-mail: fdupless@asu.edu, E-mail: tvachasp@asu.edu

Inter-galactic magnetic fields can imprint their structure on the morphology of blazar-induced gamma ray halos. We show that the halo morphology arises through the interplay of the source's jet and a two-dimensional surface dictated by the magnetic field. Through extensive numerical simulations, we generate mock halos created by stochastic magnetic fields with and without helicity, and study the dependence of the halo features on the properties of the magnetic field. We propose a sharper version of the Q-statistics and demonstrate its sensitivity to the magnetic field strength, the coherence scale, and the handedness of the helicity. We also identify andmore » explain a new feature of the Q-statistics that can further enhance its power.« less

Gauge-independent Abelian mechanism of color confinement in gluodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Tsuneo; Ishiguro, Katsuya; Sekido, Toru

Abelian mechanism of non-Abelian color confinement is observed in a gauge-independent way by high precision lattice Monte Carlo simulations in gluodynamics. An Abelian gauge field is extracted with no gauge fixing. Then we decompose the Abelian field into regular photon and singular monopole parts using the Hodge decomposition. We find that only the monopole part is responsible for the string tension. The investigation of the flux-tube profile then shows that an Abelian electric field defined in an arbitrary color direction is squeezed by the monopole supercurrent with the same color direction, and the quantitative features of flux squeezing are consistentmore » with those observed previously after Abelian projections with gauge fixing. Non-Abelian color confinement is explained in the framework of the gauge-independent Abelian dual Meissner effect.« less

Jet-Surface Interaction Test: Far-Field Noise Results

NASA Technical Reports Server (NTRS)

Brown, Clifford A.

2012-01-01

Many configurations proposed for the next generation of aircraft rely on the wing or other aircraft surfaces to shield the engine noise from the observers on the ground. However, the ability to predict the shielding effect and any new noise sources that arise from the high-speed jet flow interacting with a hard surface is currently limited. Furthermore, quality experimental data from jets with surfaces nearby suitable for developing and validating noise prediction methods are usually tied to a particular vehicle concept and, therefore, very complicated. The Jet/Surface Interaction Test was intended to supply a high quality set of data covering a wide range of surface geometries and positions and jet flows to researchers developing aircraft noise prediction tools. During phase one, the goal was to measure the noise of a jet near a simple planar surface while varying the surface length and location in order to: (1) validate noise prediction schemes when the surface is acting only as a jet noise shield and when the jet/surface interaction is creating additional noise, and (2) determine regions of interest for more detailed tests in phase two. To meet these phase one objectives, a flat plate was mounted on a two-axis traverse in two distinct configurations: (1) as a shield between the jet and the observer (microphone array) and (2) as a reflecting surface on the opposite side of the jet from the observer.

A Computational Fluid-Dynamics Assessment of the Improved Performance of Aerodynamic Rain Gauges

NASA Astrophysics Data System (ADS)

Colli, Matteo; Pollock, Michael; Stagnaro, Mattia; Lanza, Luca G.; Dutton, Mark; O'Connell, Enda

2018-02-01

The airflow surrounding any catching-type rain gauge when impacted by wind is deformed by the presence of the gauge body, resulting in the acceleration of wind above the orifice of the gauge, which deflects raindrops and snowflakes away from the collector (the wind-induced undercatch). The method of mounting a gauge with the collector at or below the level of the ground, or the use of windshields to mitigate this effect, is often not practicable. The physical shape of a gauge has a significant impact on its collection efficiency. In this study, we show that appropriate "aerodynamic" shapes are able to reduce the deformation of the airflow, which can reduce undercatch. We have employed computational fluid-dynamic simulations to evaluate the time-averaged airflow realized around "aerodynamic" rain gauge shapes when impacted by wind. Terms of comparison are provided by the results obtained for two standard "conventional" rain gauge shapes. The simulations have been run for different wind speeds and are based on a time-averaged Reynolds-Averaged Navier-Stokes model. The shape of the aerodynamic gauges is shown to have a positive impact on the time-averaged airflow patterns observed around the orifice compared to the conventional shapes. Furthermore, the turbulent air velocity fields for the aerodynamic shapes present "recirculating" structures, which may improve the particle-catching capabilities of the gauge collector.

Active galaxies. A strong magnetic field in the jet base of a supermassive black hole.

PubMed

Martí-Vidal, Ivan; Muller, Sébastien; Vlemmings, Wouter; Horellou, Cathy; Aalto, Susanne

2015-04-17

Active galactic nuclei (AGN) host some of the most energetic phenomena in the universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have detected a polarization signal (Faraday rotation) related to the strong magnetic field at the jet base of a distant AGN, PKS 1830-211. The amount of Faraday rotation (rotation measure) is proportional to the integral of the magnetic field strength along the line of sight times the density of electrons. The high rotation measures derived suggest magnetic fields of at least tens of Gauss (and possibly considerably higher) on scales of the order of light-days (0.01 parsec) from the black hole. Copyright © 2015, American Association for the Advancement of Science.

CONSTRAINING THE STRING GAUGE FIELD BY GALAXY ROTATION CURVES AND PERIHELION PRECESSION OF PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, Yeuk-Kwan E.; Xu Feng, E-mail: cheung@nju.edu.cn

2013-09-01

We discuss a cosmological model in which the string gauge field coupled universally to matter gives rise to an extra centripetal force and will have observable signatures on cosmological and astronomical observations. Several tests are performed using data including galaxy rotation curves of 22 spiral galaxies of varied luminosities and sizes and perihelion precessions of planets in the solar system. The rotation curves of the same group of galaxies are independently fit using a dark matter model with the generalized Navarro-Frenk-White (NFW) profile and the string model. A remarkable fit of galaxy rotation curves is achieved using the one-parameter stringmore » model as compared to the three-parameter dark matter model with the NFW profile. The average {chi}{sup 2} value of the NFW fit is 9% better than that of the string model at a price of two more free parameters. Furthermore, from the string model, we can give a dynamical explanation for the phenomenological Tully-Fisher relation. We are able to derive a relation between field strength, galaxy size, and luminosity, which can be verified with data from the 22 galaxies. To further test the hypothesis of the universal existence of the string gauge field, we apply our string model to the solar system. Constraint on the magnitude of the string field in the solar system is deduced from the current ranges for any anomalous perihelion precession of planets allowed by the latest observations. The field distribution resembles a dipole field originating from the Sun. The string field strength deduced from the solar system observations is of a similar magnitude as the field strength needed to sustain the rotational speed of the Sun inside the Milky Way. This hypothesis can be tested further by future observations with higher precision.« less

Constraining the String Gauge Field by Galaxy Rotation Curves and Perihelion Precession of Planets

NASA Astrophysics Data System (ADS)

Cheung, Yeuk-Kwan E.; Xu, Feng

2013-09-01

We discuss a cosmological model in which the string gauge field coupled universally to matter gives rise to an extra centripetal force and will have observable signatures on cosmological and astronomical observations. Several tests are performed using data including galaxy rotation curves of 22 spiral galaxies of varied luminosities and sizes and perihelion precessions of planets in the solar system. The rotation curves of the same group of galaxies are independently fit using a dark matter model with the generalized Navarro-Frenk-White (NFW) profile and the string model. A remarkable fit of galaxy rotation curves is achieved using the one-parameter string model as compared to the three-parameter dark matter model with the NFW profile. The average χ2 value of the NFW fit is 9% better than that of the string model at a price of two more free parameters. Furthermore, from the string model, we can give a dynamical explanation for the phenomenological Tully-Fisher relation. We are able to derive a relation between field strength, galaxy size, and luminosity, which can be verified with data from the 22 galaxies. To further test the hypothesis of the universal existence of the string gauge field, we apply our string model to the solar system. Constraint on the magnitude of the string field in the solar system is deduced from the current ranges for any anomalous perihelion precession of planets allowed by the latest observations. The field distribution resembles a dipole field originating from the Sun. The string field strength deduced from the solar system observations is of a similar magnitude as the field strength needed to sustain the rotational speed of the Sun inside the Milky Way. This hypothesis can be tested further by future observations with higher precision.

Canonical transformation path to gauge theories of gravity

NASA Astrophysics Data System (ADS)

Struckmeier, J.; Muench, J.; Vasak, D.; Kirsch, J.; Hanauske, M.; Stoecker, H.

2017-06-01

In this paper, the generic part of the gauge theory of gravity is derived, based merely on the action principle and on the general principle of relativity. We apply the canonical transformation framework to formulate geometrodynamics as a gauge theory. The starting point of our paper is constituted by the general De Donder-Weyl Hamiltonian of a system of scalar and vector fields, which is supposed to be form-invariant under (global) Lorentz transformations. Following the reasoning of gauge theories, the corresponding locally form-invariant system is worked out by means of canonical transformations. The canonical transformation approach ensures by construction that the form of the action functional is maintained. We thus encounter amended Hamiltonian systems which are form-invariant under arbitrary spacetime transformations. This amended system complies with the general principle of relativity and describes both, the dynamics of the given physical system's fields and their coupling to those quantities which describe the dynamics of the spacetime geometry. In this way, it is unambiguously determined how spin-0 and spin-1 fields couple to the dynamics of spacetime. A term that describes the dynamics of the "free" gauge fields must finally be added to the amended Hamiltonian, as common to all gauge theories, to allow for a dynamic spacetime geometry. The choice of this "dynamics" Hamiltonian is outside of the scope of gauge theory as presented in this paper. It accounts for the remaining indefiniteness of any gauge theory of gravity and must be chosen "by hand" on the basis of physical reasoning. The final Hamiltonian of the gauge theory of gravity is shown to be at least quadratic in the conjugate momenta of the gauge fields—this is beyond the Einstein-Hilbert theory of general relativity.

Wave breaking induced surface wakes and jets observed during a bora event

NASA Astrophysics Data System (ADS)

Jiang, Qingfang; Doyle, James D.

2005-09-01

An observational and modeling study of a bora event that occurred during the field phase of the Mesoscale Alpine Programme is presented. Research aircraft in-situ measurements and airborne remote-sensing observations indicate the presence of strong low-level wave breaking and alternating surface wakes and jets along the Croatian coastline over the Adriatic Sea. The observed features are well captured by a high-resolution COAMPS simulation. Analysis of the observations and modeling results indicate that the long-extending wakes above the boundary layer are induced by dissipation associated with the low-level wave breaking, which locally tends to accelerate the boundary layer flow beneath the breaking. Farther downstream of the high peaks, a hydraulic jump occurs in the boundary layer, which creates surface wakes. Downstream of lower-terrain (passes), the boundary layer flow stays strong, resembling supercritical flow.

Milne boost from Galilean gauge theory

NASA Astrophysics Data System (ADS)

Banerjee, Rabin; Mukherjee, Pradip

2018-03-01

Physical origin of Milne boost invariance of the Newton Cartan spacetime is traced to the effect of local Galilean boosts in its metric structure, using Galilean gauge theory. Specifically, we do not require any gauge field to understand Milne boost invariance.

Discrete element modeling of shock-induced particle jetting

NASA Astrophysics Data System (ADS)

Xue, Kun; Cui, Haoran

2018-05-01

The dispersal of particle shell or ring by divergent impulsive loads takes the form of coherent particle jets with the dimensions several orders larger than that of constituent grain. Particle-scale simulations based on the discrete element method have been carried out to reveal the evolution of jets in semi-two-dimensional rings before they burst out of the external surface. We identify two key events which substantially change the resulted jetting pattern, specifically, the annihilation of incipient jets and the tip-slipping of jets, which become active in different phases of jet evolution. Parametric investigations have been done to assess the correlations between the jetting pattern and a variety of structural parameters. Overpressure, the internal and outer diameters of ring as well as the packing density are found to have effects on the jet evolution with different relative importance.

Radiation from Relativistic Jets

NASA Technical Reports Server (NTRS)

Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

2008-01-01

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Experimental study of near-field air entrainment by subsonic volcanic jets

USGS Publications Warehouse

Solovitz, Stephen A.; Mastin, Larry G.

2009-01-01

The flow structure in the developing region of a turbulent jet has been examined using particle image velocimetry methods, considering the flow at steady state conditions. The velocity fields were integrated to determine the ratio of the entrained air speed to the jet speed, which was approximately 0.03 for a range of Mach numbers up to 0.89 and Reynolds numbers up to 217,000. This range of experimental Mach and Reynolds numbers is higher than previously considered for high-accuracy entrainment measures, particularly in the near-vent region. The entrainment values are below those commonly used for geophysical analyses of volcanic plumes, suggesting that existing 1-D models are likely to understate the tendency for column collapse.

Numerical Simulations of Chromospheric Anemone Jets Associated with Moving Magnetic Features

NASA Astrophysics Data System (ADS)

Yang, Liping; He, Jiansen; Peter, Hardi; Tu, Chuanyi; Zhang, Lei; Feng, Xueshang; Zhang, Shaohua

2013-11-01

Observations with the space-based solar observatory Hinode show that small-scale magnetic structures in the photosphere are found to be associated with a particular class of jets of plasma in the chromosphere called anemone jets. The goal of our study is to conduct a numerical experiment of such chromospheric anemone jets related to the moving magnetic features (MMFs). We construct a 2.5 dimensional numerical MHD model to describe the process of magnetic reconnection between the MMFs and the pre-existing ambient magnetic field, which is driven by the horizontal motion of the magnetic structure in the photosphere. We include thermal conduction parallel to the magnetic field and optically thin radiative losses in the corona to account for a self-consistent description of the evaporation process during the heating of the plasma due to the reconnection process. The motion of the MMFs leads to the expected jet and our numerical results can reproduce many observed characteristics of chromospheric anemone jets, topologically and quantitatively. As a result of the tearing instability, plasmoids are generated in the reconnection process that are consistent with the observed bright moving blobs in the anemone jets. An increase in the thermal pressure at the base of the jet is also driven by the reconnection, which induces a train of slow-mode shocks propagating upward. These shocks are a secondary effect, and only modulate the outflow of the anemone jet. The jet itself is driven by the energy input due to the reconnection of the MMFs and the ambient magnetic field.

Simultaneous velocity and concentration measurements in the near field of a turbulent low-pressure jet by digital particle image velocimetry-planar laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Borg, A.; Bolinder, J.; Fuchs, L.

The main purpose of this work is to develop a method for simultaneous measurement of velocity and passive scalar concentration by means of digital particle image velocimetry and planar laser-induced fluorescence. Details of the implementation of the method are given, and the technique is applied to measurements of concentration and velocity in the centre-plane of a liquid jet with a Reynolds number of 6,000. The measurements are compared with large eddy simulations. Mean velocities and concentrations, fluctuating velocities and concentrations, and correlation between fluctuating velocities and concentrations are analysed for the first six diameters downstream of the jet exit. The general agreement between measured and simulated results was found to be good, in particular for mean quantities. Mean profiles are also found to be in good agreement with other experimental work on jets reported in the literature. The ``whole-plane'' measurement method was found to be very useful for detailed comparisons of turbulent statistics with simulated data. The inadequacy of models for turbulent mass transport based on the standard gradient diffusion concept is demonstrated through the experimental data.

Prediction of the Acoustic Field Associated with Instability Wave Source Model for a Compressible Jet

NASA Technical Reports Server (NTRS)

Golubev, Vladimir; Mankbadi, Reda R.; Dahl, Milo D.; Kiraly, L. James (Technical Monitor)

2002-01-01

This paper provides preliminary results of the study of the acoustic radiation from the source model representing spatially-growing instability waves in a round jet at high speeds. The source model is briefly discussed first followed by the analysis of the produced acoustic directivity pattern. Two integral surface techniques are discussed and compared for prediction of the jet acoustic radiation field.

Gauged multisoliton baby Skyrme model

NASA Astrophysics Data System (ADS)

Samoilenka, A.; Shnir, Ya.

2016-03-01

We present a study of U (1 ) gauged modification of the 2 +1 -dimensional planar Skyrme model with a particular choice of the symmetry breaking potential term which combines a short-range repulsion and a long-range attraction. In the absence of the gauge interaction, the multisolitons of the model are aloof, as they consist of the individual constituents which are well separated. A peculiar feature of the model is that there are usually several different stable static multisoliton solutions of rather similar energy in a topological sector of given degree. We investigate the pattern of the solutions and find new previously unknown local minima. It is shown that coupling of the aloof planar multi-Skyrmions to the magnetic field strongly affects the pattern of interaction between the constituents. We analyze the dependency of the structure of the solutions, their energies, and magnetic fluxes on the strength of the gauge coupling. It is found that, generically, in the strong coupling limit, the coupling to the gauge field results in effective recovery of the rotational invariance of the configuration.

Protostellar Jets: The Revolution with ALMA

NASA Astrophysics Data System (ADS)

Podio, Linda

2017-11-01

Fast and collimated molecular jets as well as slower wide-angle outflows are observed since the earliest stages of the formation of a new star, when the protostellar embryo accretes most of its final mass from the dense parental envelope. Early theoretical studies suggested that jets have a key role in this process as they can transport away angular momentum thus allowing the star to form without reaching its break-up speed. However, an observational validation of these theories is still challenging as it requires to investigate the interface between jets and disks on scales of fractions to tens of AUs. For this reason, many questions about the origin and feedback of protostellar jets remain unanswered, e.g. are jets ubiquitous at the earliest stages of star formation? Are they launched by a magneto-centrifugal mechanism as suggested by theoretical models? Are they able to remove (enough) angular momentum? What is the jet/outflow feedback on the forming star-disk system in terms of transported mass/momentum and shock-induced chemical alterations? The advent of millimetre interferometers such as NOEMA and ALMA with their unprecedented combination of angular resolution and sensitivity are now unraveling the core of pristine jet-disk systems. While NOEMA allows to obtain the first statistically relevant surveys of protostellar jet properties and ubiquity, recent ALMA observations provide the first solid signatures of jet rotation and new insight on the chemistry of the protostellar region. I will review the most recent and exciting results obtained in the field and show how millimetre interferometry is revolutionising our comprehension of protostellar jets.

Solar Polar Jets Driven by Magnetic Reconnection, Gravity, and Wind

NASA Astrophysics Data System (ADS)

DeVore, C. Richard; Karpen, Judith T.; Antiochos, Spiro K.

2014-06-01

Polar jets are dynamic, narrow, radially extended structures observed in solar EUV emission near the limb. They originate within the open field of coronal holes in “anemone” regions, which are intrusions of opposite magnetic polarity. The key topological feature is a magnetic null point atop a dome-shaped fan surface of field lines. Applied stresses readily distort the null into a current patch, eventually inducing interchange reconnection between the closed and open fields inside and outside the fan surface (Antiochos 1996). Previously, we demonstrated that magnetic free energy stored on twisted closed field lines inside the fan surface is released explosively by the onset of fast reconnection across the current patch (Pariat et al. 2009, 2010). A dense jet comprised of a nonlinear, torsional Alfvén wave is ejected into the outer corona along the newly reconnected open field lines. Now we are extending those exploratory simulations by including the effects of solar gravity, solar wind, and expanding spherical geometry. We find that the model remains robust in the resulting more complex setting, with explosive energy release and dense jet formation occurring in the low corona due to the onset of a kink-like instability, as found in the earlier Cartesian, gravity-free, static-atmosphere cases. The spherical-geometry jet including gravity and wind propagates far more rapidly into the outer corona and inner heliosphere than a comparison jet simulation that excludes those effects. We report detailed analyses of our new results, compare them with previous work, and discuss the implications for understanding remote and in-situ observations of solar polar jets.This work was supported by NASA’s LWS TR&T program.

A BRST gauge-fixing procedure for Yang Mills theory on sphere

NASA Astrophysics Data System (ADS)

Banerjee, Rabin; Deguchi, Shinichi

2006-01-01

A gauge-fixing procedure for the Yang-Mills theory on an n-dimensional sphere (or a hypersphere) is discussed in a systematic manner. We claim that Adler's gauge-fixing condition used in massless Euclidean QED on a hypersphere is not conventional because of the presence of an extra free index, and hence is unfavorable for the gauge-fixing procedure based on the BRST invariance principle (or simply BRST gauge-fixing procedure). Choosing a suitable gauge condition, which is proved to be equivalent to a generalization of Adler's condition, we apply the BRST gauge-fixing procedure to the Yang-Mills theory on a hypersphere to obtain consistent results. Field equations for the Yang-Mills field and associated fields are derived in manifestly O (n + 1) covariant or invariant forms. In the large radius limit, these equations reproduce the corresponding field equations defined on the n-dimensional flat space.

Theoretical princi les of constructing the equations of motion for a spin color-charged particle in gauge and fermion fields

NASA Astrophysics Data System (ADS)

Markov, Yu. A.; Shishmarev, A. A.

2010-11-01

Based on the most general principles of materiality, gauge, and re-parameterized invariance, the problem of constructing an action describing the dynamics of a classical color-charged particle moving in external non-Abelian gauge and fermion fields is considered. The case of a linear Lagrangian dependence on the external fermion fields is discussed. Within the framework of the description of the color degree of freedom of the particle with half-integer spin by the Grassmann color charges, a new concept of the Grassmann color source of the particle being a fermion analog of the conventional color current is introduced.

Inductive Measurement of Plasma Jet Electrical Conductivity

NASA Technical Reports Server (NTRS)

Turner, Matthew W.; Hawk, Clark W.; Litchford, Ron J.

2005-01-01

An inductive probing scheme, originally developed for shock tube studies, has been adapted to measure explosive plasma jet conductivities. In this method, the perturbation of an applied magnetic field by a plasma jet induces a voltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-inch diameter probe was designed and constructed, and calibration was accomplished by firing an aluminum slug through the probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-gram high explosive shaped charges. Measured conductivities were in the range of 3 kS/m for unseeded octol charges and 20 kS/m for seeded octol charges containing 2% potassium carbonate by mass.

Laboratory modeling of multiple zonal jets on the polar beta-plane

NASA Astrophysics Data System (ADS)

Afanasyev, Y.

2011-12-01

Zonal jets observed in the oceans and atmospheres of planets are studied in a laboratory rotating tank. The fluid layer in the rotating tank has parabolic free surface and dynamically simulates the polar beta-plane where the Coriolis parameter varies quadratically with distance from the pole. Velocity and surface elevation fields are measured with an optical altimetry method (Afanasyev et al., Exps Fluids 2009). The flows are induced by a localized buoyancy source along radial direction. The baroclinic flow consisting of a field of eddies propagates away from the source due West and forms zonal jets (Fig. 1). Barotropic jets ahead of the baroclinic flow are formed by radiation of beta plumes. Inside the baroclinic flow the jets flow between the chains of eddies. Experimental evidence of so-called noodles (baroclinic instability mode with motions in the radial, North-South direction) theoretically predicted by Berloff et al. (JFM, JPO 2009) was found in our experiments. Beta plume radiation mechanism and the mechanism associated with the instability of noodles are likely to contribute to formation of jets in the baroclinic flow.

Gauge interactions theory and experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zichichi, A.

This volume brings together physicists from around the world to report and discuss the exciting advances made recently in theoretical and experimental aspects of gauge interactions. Following a presentation of the theoretical foundations of and recent developments in gauge fields, the contrib utors fogus on supersymmetry, the derivation of Higgs particles from gauge fields, and heavy leptons. Other chapters discuss the use of quantum chromodynamics in describing basic interactions among quarks and gluons, in predicting the existence of glueballs, and in application to heavy flavor production in strong interactions. The editor, Antonino Zichichi, provides a study of the multiparticle hadronicmore » systems produced in highenergy soft (pp) interactions. Other interesting chapters deal with photon scattering at very high energies and theoretical alternatives to the electroweak model, and the volume concludes with proposals for future experimental facilities for European physics.« less

Axis switching and spreading of an asymmetric jet: Role of vorticity dynamics

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.

1994-01-01

The effects of vortex generators and periodic excitation on vorticity dynamics and the phenomenon of axis switching in a free asymmetric jet are studied experimentally. Most of the data reported are for a 3:1 rectangular jet at a Reynolds number of 450,000 and a Mach number of 0.31. The vortex generators are in the form of 'delta tabs', triangular shaped protrusions into the flow, placed at the nozzle exit. With suitable placement of the tabs, axis switching could be either stopped or augmented. Two mechanisms are identified governing the phenomenon. One, as described by previous researchers and referred to here as the omega(sub theta)-induced dynamics, is due to difference in induced velocities for different segments of a rolled up azimuthal vortical structure. The other, omega(sub x)-induced dynamics, is due to the induced velocities of streamwise vortex pairs in the flow. Both dynamics can be active in a natural asymmetric jet; the tendency for axis switching caused by the omega(sub theta)-induced dynamics may be, depending on the streamwise vorticity distribution, either resisted or enhanced by the omega(sub x)-induced dynamics. While this simple framework qualitatively explains the various observations made on axis switching, mechanisms actually in play may be much more complex. The two dynamics are not independent as the flow field is replete with both azimuthal and streamwise vortical structures which continually interact. Phase averaged flow field data for a periodically forced case, over a volume of the flow field, are presented and discussed in an effort to gain insight into the dynamics of these vortical structures.

Dynamical gauge effects in an open quantum network

NASA Astrophysics Data System (ADS)

Zhao, Jianshi; Price, Craig; Liu, Qi; Gemelke, Nathan

2016-05-01

We describe new experimental techniques for simulation of high-energy field theories based on an analogy between open thermodynamic systems and effective dynamical gauge-fields following SU(2) × U(1) Yang-Mills models. By coupling near-resonant laser-modes to atoms moving in a disordered optical environment, we create an open system which exhibits a non-equilibrium phase transition between two steady-state behaviors, exhibiting scale-invariant behavior near the transition. By measuring transport of atoms through the disordered network, we observe two distinct scaling behaviors, corresponding to the classical and quantum limits for the dynamical gauge field. This behavior is loosely analogous to dynamical gauge effects in quantum chromodynamics, and can mapped onto generalized open problems in theoretical understanding of quantized non-Abelian gauge theories. Additional, the scaling behavior can be understood from the geometric structure of the gauge potential and linked to the measure of information in the local disordered potential, reflecting an underlying holographic principle. We acknowledge support from NSF Award No.1068570, and the Charles E. Kaufman Foundation.

Appearance of gauge structure in simple dynamical systems

NASA Technical Reports Server (NTRS)

Wilczek, F.; Zee, A.

1984-01-01

By generalizing a construction of Berry and Simon, it is shown that non-Abelian gauge fields arise in the adiabatic development of simple quantum mechanical systems. Characteristics of the gauge fields are related to energy splittings, which may be observable in real systems. Similar phenomena are found for suitable classical systems.

Advances in the evaluation of wind-induced undercatch using CFD-based simulations of snow gauge performance

NASA Astrophysics Data System (ADS)

Colli, Matteo; Lanza, Luca; Rasmussen, Roy; Thériault, Julie

2016-04-01

Despite its importance, accurate measurements of precipitation remains a challenge. Measurement errors for solid precipitation, which are often ignored for automated systems, frequently range from 20% to 70% due to undercatch in windy conditions. While solid precipitation measurements have been the subject of many studies, there have been only a limited number of numerical modeling efforts to estimate the collection efficiency of solid precipitation gauges when exposed to the wind, in both shielded and unshielded configurations. The available models use CFD simulations of the airflow pattern generated by the aerodynamic response of the gauge/shield geometry to perform the Lagrangian tracking of solid precipitation particles (Thériault et al., 2012; Colli et al. 2016a and 2016b). Validation of the results against field observations yields similarities in the overall behavior, but the model output only approximately reproduces the dependence of the experimental collection efficiency on wind speed. We present recent developments of such a modelling approach including various gauge/shield configurations, the influence of the drag coefficient calculation on the model performance, and the role of the particle size distribution in explaining the scatter of the collection efficiency observed at any particular wind speed (Colli et al. 2015). Comparison with observations at the Marshall (CO) field test site is used to validate results of the various modelling schemes and to support the analysis of the microphysical characteristics of ice crystals. References: Colli, M., Rasmussen, R.M., Thèriault, J.M., Lanza, L.G., Baker, B.C. and J. Kochendorfer (2015). An improved trajectory model to evaluate the collection performance of snow gauges. J.Appl.Meteor.Climatol., 54(8), pages 1826-1836. Colli, M., Lanza, L.G., Rasmussen, R.M. and J.M. Thèriault (2016a). The collection efficiency of shielded and unshielded precipitation gauges. Part I: CFD airflow modelling. J. of

Dynamic response of induced pressures, suckdown, and temperatures for two tandem jet STOVL configurations

NASA Technical Reports Server (NTRS)

Wardwell, Douglas A.; Corsiglia, Victor R.; Kuhn, Richard E.

1992-01-01

NASA Ames Research Center has been conducting a program to improve the methods for predicting the jet-induced lift loss (suckdown) and hot gas ingestion on jet Short Takeoff and Vertical Landing (STOVL) aircraft during hover near the ground. As part of that program, small-scale hover tests were conducted to expand the current data base and to improve upon the current empirical methods for predicting jet-induced lift loss and hot gas ingestion (HGI) effects. This report is one of three data reports covering data obtained from hover tests conducted at Lockheed Aeronautical Systems, Rye Canyon Facility. It will include dynamic (time dependent) test data for both lift loss and HGI parameters (height, nozzle temperature, nozzle pressure ratio, and inlet location). The flat plate models tested were tandem jet configurations with three planform variations and variable position side-by-side sucking inlets mounted above the planform. Temperature time lags from 8-15 seconds were observed before the model temperatures stabilize. This was larger than the expected 1.5-second lag calculated from literature. Several possible explanations for the flow temperatures to stabilize may include some, or all, of the following: thermocouple lag, radiation to the model surface, and heat loss to the ground board. Further investigations are required to understand the reasons for this temperature lag.

Scalar quantum electrodynamics via Duffin-Kemmer-Petiau gauge theory in the Heisenberg picture: Vacuum polarization

NASA Astrophysics Data System (ADS)

Beltran, J.; Maia, N. T.; Pimentel, B. M.

2018-04-01

Scalar Quantum Electrodynamics is investigated in the Heisenberg picture via the Duffin-Kemmer-Petiau gauge theory. On this framework, a perturbative method is used to compute the vacuum polarization tensor and its corresponding induced current for the case of a charged scalar field in the presence of an external electromagnetic field. Charge renormalization is brought into discussion for the interpretation of the results for the vacuum polarization.

Flow Field Characterization of an Angled Supersonic Jet Near a Bluff Body

NASA Technical Reports Server (NTRS)

Wolter, John D.; Childs, Robert; Wernet, Mark P.; Shestopalov, Andrea; Melton, John E.

2011-01-01

An experiment was performed to acquire data from a hot supersonic jet in cross flow for the purpose of validating computational fluid dynamics (CFD) turbulence modeling relevant to the Orion Launch Abort System. Hot jet conditions were at the highest temperature and pressure that could be acquired in the test facility. The nozzle pressure ratio was 28.5, and the nozzle temperature ratio was 3. These conditions are different from those of the flight vehicle, but sufficiently high to model the observed turbulence features. Stereo Particle Image Velocimetry (SPIV) data and capsule pressure data are presented. Features of the flow field are presented and discussed

Experimental investigation of a jet inclined to a subsonic crossflow

NASA Technical Reports Server (NTRS)

Aoyagi, K.; Snyder, P. K.

1981-01-01

Experimental investigations have been conducted to determine the surface-pressure distribution on a flat plate and a body of revolution with a jet issuing at a large angle to the free stream and to obtain a better understanding of the entrainment mechanism close to the jet exit by quantitative mean velocity surveys. Pressure data were obtained with a flat plate model at several nozzle injection angles using a single round nozzle. For the body of revolution model, data were obtained with a round jet exhausting perpendicular to the crossflow and with two round jets spaced two to six nozzle diameters apart. Mean velocity measurements were obtained with laser velocimeter surveys near the base of a round jet exhausting normal to a flat plate. For the flat plate model, the pressure field shifts downstream and the entrainment effect decreases with decreasing nozzle injection angle. For the body of revolution model with two jets, the jet-induced effect of the rear jet on the surface-pressure distribution was less than the front jet. The flow regions close to the jet are defined by the laser surveys, but further mean velocity surveys are required to understand the entrainment mechanism.

Generating Long Scale-Length Plasma Jets Embedded in a Uniform, Multi-Tesla Magnetic-Field

NASA Astrophysics Data System (ADS)

Manuel, Mario; Kuranz, Carolyn; Rasmus, Alex; Klein, Sallee; Fein, Jeff; Belancourt, Patrick; Drake, R. P.; Pollock, Brad; Hazi, Andrew; Park, Jaebum; Williams, Jackson; Chen, Hui