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Sample records for magnetized compact objects

  1. Thermodynamics of magnetized binary compact objects

    SciTech Connect

    Uryu, Koji; Gourgoulhon, Eric; Markakis, Charalampos

    2010-11-15

    Binary systems of compact objects with electromagnetic field are modeled by helically symmetric Einstein-Maxwell spacetimes with charged and magnetized perfect fluids. Previously derived thermodynamic laws for helically symmetric perfect-fluid spacetimes are extended to include the electromagnetic fields, and electric currents and charges; the first law is written as a relation between the change in the asymptotic Noether charge {delta}Q and the changes in the area and electric charge of black holes, and in the vorticity, baryon rest mass, entropy, charge and magnetic flux of the magnetized fluid. Using the conservation laws of the circulation of magnetized flow found by Bekenstein and Oron for the ideal magnetohydrodynamic fluid, and also for the flow with zero conducting current, we show that, for nearby equilibria that conserve the quantities mentioned above, the relation {delta}Q=0 is satisfied. We also discuss a formulation for computing numerical solutions of magnetized binary compact objects in equilibrium with emphasis on a first integral of the ideal magnetohydrodynamic-Euler equation.

  2. A SCILAB Program for Computing Rotating Magnetic Compact Objects

    NASA Astrophysics Data System (ADS)

    Papasotiriou, P. J.; Geroyannis, V. S.

    We implement the so-called ``complex-plane iterative technique'' (CIT) to the computation of classical differentially rotating magnetic white dwarf and neutron star models. The program has been written in SCILAB (© INRIA-ENPC), a matrix-oriented high-level programming language, which can be downloaded free of charge from the site http://www-rocq.inria.fr/scilab. Due to the advanced capabilities of this language, the code is short and understandable. Highlights of the program are: (a) time-saving character, (b) easy use due to the built-in graphics user interface, (c) easy interfacing with Fortran via online dynamic link. We interpret our numerical results in various ways by extensively using the graphics environment of SCILAB.

  3. Von Zeipel's theorem for a magnetized circular flow around a compact object

    NASA Astrophysics Data System (ADS)

    Zanotti, O.; Pugliese, D.

    2015-04-01

    We analyze a class of physical properties, forming the content of the so-called von Zeipel theorem, which characterizes stationary, axisymmetric, non-selfgravitating perfect fluids in circular motion in the gravitational field of a compact object. We consider the extension of the theorem to the magnetohydrodynamic regime, under the assumption of an infinitely conductive fluid, both in the Newtonian and in the relativistic framework. When the magnetic field is toroidal, the conditions required by the theorem are equivalent to integrability conditions, as it is the case for purely hydrodynamic flows. When the magnetic field is poloidal, the analysis for the relativistic regime is substantially different with respect to the Newtonian case and additional constraints, in the form of PDEs, must be imposed on the magnetic field in order to guarantee that the angular velocity depends only on the specific angular momentum . In order to deduce such physical constraints, it is crucial to adopt special coordinates, which are adapted to the surfaces. The physical significance of these results is briefly discussed.

  4. TRANSITION FROM REGULAR TO CHAOTIC CIRCULATION IN MAGNETIZED CORONAE NEAR COMPACT OBJECTS

    SciTech Connect

    Kopacek, O.; Karas, V.; Kovar, J.; StuchlIk, Z.

    2010-10-20

    Accretion onto black holes and compact stars brings material in a zone of strong gravitational and electromagnetic fields. We study dynamical properties of motion of electrically charged particles forming a highly diluted medium (a corona) in the regime of strong gravity and large-scale (ordered) magnetic field. We start our work from a system that allows regular motion, then we focus on the onset of chaos. To this end, we investigate the case of a rotating black hole immersed in a weak, asymptotically uniform magnetic field. We also consider a magnetic star, approximated by the Schwarzschild metric and a test magnetic field of a rotating dipole. These are two model examples of systems permitting energetically bound, off-equatorial motion of matter confined to the halo lobes that encircle the central body. Our approach allows us to address the question of whether the spin parameter of the black hole plays any major role in determining the degree of the chaoticness. To characterize the motion, we construct the recurrence plots (RPs) and we compare them with Poincare surfaces of section. We describe the RPs in terms of the recurrence quantification analysis, which allows us to identify the transition between different dynamical regimes. We demonstrate that this new technique is able to detect the chaos onset very efficiently and provide its quantitative measure. The chaos typically occurs when the conserved energy is raised to a sufficiently high level that allows the particles to traverse the equatorial plane. We find that the role of the black hole spin in setting the chaos is more complicated than initially thought.

  5. DC CIRCUIT POWERED BY ORBITAL MOTION: MAGNETIC INTERACTIONS IN COMPACT OBJECT BINARIES AND EXOPLANETARY SYSTEMS

    SciTech Connect

    Lai Dong

    2012-09-20

    The unipolar induction DC circuit model, originally developed by Goldreich and Lynden-Bell for the Jupiter-Io system, has been applied to different types of binary systems in recent years. We show that there exists an upper limit to the magnetic interaction torque and energy dissipation rate in such a model. This arises because when the resistance of the circuit is too small, the large current flow severely twists the magnetic flux tube connecting the two binary components, leading to the breakdown of the circuit. Applying this limit, we find that in coalescing neutron star binaries, magnetic interactions produce negligible correction to the phase evolution of the gravitational waveform, even for magnetar-like field strengths. However, energy dissipation in the binary magnetosphere may still give rise to electromagnetic radiation prior to the final merger. For ultracompact white dwarf binaries, we find that unipolar induction does not provide adequate energy dissipation to explain the observed X-ray luminosities of several sources. For exoplanetary systems containing close-in Jupiters or super-Earths, the magnetic torque and energy dissipation induced by the orbital motion are negligible, except possibly during the early T Tauri phase, when the stellar magnetic field is stronger than 10{sup 3} G.

  6. Compact objects in Horndeski gravity

    NASA Astrophysics Data System (ADS)

    Silva, Hector O.; Maselli, Andrea; Minamitsuji, Masato; Berti, Emanuele

    2016-04-01

    Horndeski gravity holds a special position as the most general extension of Einstein’s theory of general relativity (GR) with a single scalar degree of freedom and second-order field equations. Because of these features, Horndeski gravity is an attractive phenomenological playground to investigate the consequences of modifications of GR in cosmology and astrophysics. We present a review of the progress made so far in the study of compact objects (black holes (BHs) and neutron stars (NSs)) within Horndeski gravity. In particular, we review our recent work on slowly rotating BHs and present some new results on slowly rotating NSs.

  7. Tidal deformations of a spinning compact object

    NASA Astrophysics Data System (ADS)

    Pani, Paolo; Gualtieri, Leonardo; Maselli, Andrea; Ferrari, Valeria

    2015-07-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the tidal Love numbers in general relativity, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution, even in the static case. By extending the standard procedure to identify the linear response in the static case, we prove analytically that the Love numbers of a Kerr black hole remain zero to second order in the spin. As a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed Kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties.

  8. On the diversity of compact objects within supernova remnants - I. A parametric model for magnetic field evolution

    NASA Astrophysics Data System (ADS)

    Rogers, Adam; Safi-Harb, Samar

    2016-04-01

    A wealth of X-ray and radio observations has revealed in the past decade a growing diversity of neutron stars (NSs) with properties spanning orders of magnitude in magnetic field strength and ages, and with emission processes explained by a range of mechanisms dictating their radiation properties. However, serious difficulties exist with the magneto-dipole model of isolated NS fields and their inferred ages, such as a large range of observed braking indices (n, with values often <3) and a mismatch between the NS and associated supernova remnant (SNR) ages. This problem arises primarily from the assumptions of a constant magnetic field with n = 3, and an initial spin period that is much smaller than the observed current period. It has been suggested that a solution to this problem involves magnetic field evolution, with some NSs having magnetic fields buried within the crust by accretion of fall-back supernova material following their birth. In this work, we explore a parametric phenomenological model for magnetic field growth that generalizes previous suggested field evolution functions, and apply it to a variety of NSs with both secure SNR associations and known ages. We explore the flexibility of the model by recovering the results of previous work on buried magnetic fields in young NSs. Our model fits suggest that apparently disparate classes of NSs may be related to one another through the time evolution of the magnetic field.

  9. Modeling the X-rays from the central compact object PSR J1852+0040 in Kesteven 79: Evidence for a strongly magnetized neutron star

    SciTech Connect

    Bogdanov, Slavko

    2014-08-01

    I present modeling of the X-ray pulsations from the central compact object (CCO) PSR J1852+0040 in the Galactic supernova remnant Kesteven 79. In the context of thermal surface radiation from a rotating neutron star (NS), a conventional polar cap model can reproduce the broad, large-amplitude X-ray pulse only with a 'pencil plus fan' beam emission pattern, which is characteristic of ≳ 10{sup 12} G NS atmospheres, much greater than the ∼10{sup 10} G external dipole field inferred from the pulsar spin-down rate. This discrepancy can be explained by an axially displaced dipole. For other beaming patterns, it is necessary to invoke high-aspect-ratio emitting regions that are greatly longitudinally elongated, possibly due to an extremely offset dipole. For all assumed emission models, the existence of strong internal magnetic fields (≳ 10{sup 14} G) that preferentially channel internal heat to only a portion of the exterior is required to account for the implied high-temperature contrast across the stellar surface. This lends further observational evidence in support of the 'hidden' strong magnetic field scenario, in which CCOs possess submerged magnetic fields that are substantially stronger than the external dipole field, presumably due to burial by fallback of supernova ejecta. I also conduct phase-resolved X-ray spectroscopy and find no evidence for prominent spin-phase-dependent absorption features that could be produced by cyclotron absorption/scattering.

  10. Compact magnetic energy storage module

    DOEpatents

    Prueitt, Melvin L.

    1994-01-01

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module.

  11. Compact magnetic energy storage module

    DOEpatents

    Prueitt, M.L.

    1994-12-20

    A superconducting compact magnetic energy storage module in which a plurality of superconducting toroids, each having a toroidally wound superconducting winding inside a poloidally wound superconducting winding, are stacked so that the flow of electricity in each toroidally wound superconducting winding is in a direction opposite from the direction of electrical flow in other contiguous superconducting toroids. This allows for minimal magnetic pollution outside of the module. 4 figures.

  12. Double compact objects. II. Cosmological merger rates

    SciTech Connect

    Dominik, Michal; Belczynski, Krzysztof; Bulik, Tomasz; Fryer, Christopher; Holz, Daniel E.; Berti, Emanuele; Mandel, Ilya; O'Shaughnessy, Richard

    2013-12-10

    The development of advanced gravitational wave (GW) observatories, such as Advanced LIGO and Advanced Virgo, provides impetus to refine theoretical predictions for what these instruments might detect. In particular, with the range increasing by an order of magnitude, the search for GW sources is extending beyond the 'local' universe and out to cosmological distances. Double compact objects (neutron star-neutron star (NS-NS), black hole-neutron star (BH-NS), and black hole-black hole (BH-BH) systems) are considered to be the most promising GW sources. In addition, NS-NS and/or BH-NS systems are thought to be the progenitors of gamma-ray bursts and may also be associated with kilonovae. In this paper, we present the merger event rates of these objects as a function of cosmological redshift. We provide the results for four cases, each one investigating a different important evolution parameter of binary stars. Each case is also presented for two metallicity evolution scenarios. We find that (1) in most cases NS-NS systems dominate the merger rates in the local universe, while BH-BH mergers dominate at high redshift, (2) BH-NS mergers are less frequent than other sources per unit volume, for all time, and (3) natal kicks may alter the observable properties of populations in a significant way, allowing the underlying models of binary evolution and compact object formation to be easily distinguished. This is the second paper in a series of three. The third paper will focus on calculating the detection rates of mergers by GW telescopes.

  13. MACHO (MAssive Compact Halo Objects) Data

    DOE Data Explorer

    The primary aim of the MACHO Project is to test the hypothesis that a significant fraction of the dark matter in the halo of the Milky Way is made up of objects like brown dwarfs or planets: these objects have come to be known as MACHOs, for MAssive Compact Halo Objects. The signature of these objects is the occasional amplification of the light from extragalactic stars by the gravitational lens effect. The amplification can be large, but events are extremely rare: it is necessary to monitor photometrically several million stars for a period of years in order to obtain a useful detection rate. For this purpose MACHO has a two channel system that employs eight CCDs, mounted on the 50 inch telescope at Mt. Stromlo. The high data rate (several GBytes per night) is accommodated by custom electronics and on-line data reduction. The Project has taken more than 27,000 images with this system since June 1992. Analysis of a subset of these data has yielded databases containing light curves in two colors for 8 million stars in the LMC and 10 million in the bulge of the Milky Way. A search for microlensing has turned up four candidates toward the Large Magellanic Cloud and 45 toward the Galactic Bulge. The web page for data provides links to MACHO Project data portals and various specialized interfaces for viewing or searching the data. (Specialized Interface)

  14. The lack of large compact symmetric objects

    NASA Astrophysics Data System (ADS)

    Augusto, P.

    2009-02-01

    In recent years, `baby' (< 103 yr) and `young' (103-105 yr) radio galaxies have been found and classified, although their numbers are still small (tens). Also, they have many different names, depending on the type of survey and scientific context in which they were found: compact steep spectrum sources (CSS), giga-Hertz peaked spectrum sources (GPS) and compact-medium symmetric objects (C-MSO). The latter have the radio galaxy structure more obvious and correspond to the `babies' (CSOs; < 1 kpc) and `young' (MSOs; 1-15 kpc) radio galaxies. The log-size distribution of CSOs shows a sharp drop at 0.3 kpc. This trend continues through flat-spectrum MSOs (over the full 1-15 kpc size range). In order to find out if this lack of large CSOs and flat-spectrum MSOs is due to poor sampling (lack of surveys that probe efficiently the 0.3-15 kpc size range) and/or has physical meaning (e.g. if the lobes of CSOs expand as they grow and age, they might become CSSs, `disappearing' from the flat-spectrum MSO statistics), we have built a sample of 157 flat-spectrum radio sources with structure on ˜0.3-15 kpc scales. We are using new, archived and published data to produce and inspect hundreds of multi-frequency multi-instrument maps and models. We have already found 13 new secure CSO/MSOs. We expect to uncover ˜30-40 new CSOs and MSOs, most on the 0.3-15 kpc size range, when our project is complete.

  15. Probing the Environment of Accreting Compact Objects

    NASA Astrophysics Data System (ADS)

    Hanke, Manfred

    2011-04-01

    X-ray binaries are the topic of this thesis. They consist of a compact object -- a black hole or a neutron star -- and an ordinary star, which loses matter to the compact object. The gravitational energy released through this process of mass accretion is largely converted into X-rays. The latter are used in the present work to screen the environment of the compact object. The main focus in the case of a massive star is on its wind, which is not homogeneous, but may display structures in form of temperature and density variations. Since great importance is, in multiple respects, attached to stellar winds in astrophysics, there is large interest in general to understand these structures more thoroughly. In particular for X-ray binaries, whose compact object obtains matter from the wind of its companion star, the state of the wind can decisively influence mass accretion and its related radiation processes. A detailed introduction to the fundamentals of stellar winds, compact objects, accretion and radiation processes in X-ray binaries, as well as to the employed instruments and analysis methods, is given in chapter 1. The focus of this investigation is on Cygnus X-1, a binary system with a black hole and a blue supergiant, which form a persistently very bright X-ray source because of accretion from the stellar wind. It had been known for a long time that this source -- when the black hole is seen through the dense stellar wind -- often displays abrupt absorption events whose origin is suspected to be in clumps in the wind. More detailed physical properties of these clumps and of the wind in general are explored in this work. Observations that were specifically acquired for this study, as well as archival data from different satellite observatories, are analyzed in view of signatures of the wind and its fine structures. These results are presented in chapter 2. In a first part of the analysis, the statistical distribution of the brightness of Cyg X-1, as measured since

  16. Accretion Disk Outflows from Compact Object Mergers

    NASA Astrophysics Data System (ADS)

    Metzger, Brian

    Nuclear reactions play a key role in the accretion disks and outflows associated with the merger of binary compact objects and the central engines of gamma-ray bursts and supernovae. The proposed research program will investigate the impact of nucleosynthesis on these events and their observable signatures by means of analytic calculations and numerical simulations. One focus of this research is rapid accretion following the tidal disruption of a white dwarf (WD) by a neutron star (NS) or black hole (BH) binary companion. Tidal disruption shreds the WD into a massive torus composed of C, O, and/or He, which undergoes nuclear reactions and burns to increasingly heavier elements as it flows to smaller radii towards the central compact object. The nuclear energy so released is comparable to that released gravitationally, suggesting that burning could drastically alter the structure and stability of the accretion flow. Axisymmetric hydrodynamic simulations of the evolution of the torus including nuclear burning will be performed to explore issues such as the mass budget of the flow (accretion vs. outflows) and its thermal stability (steady burning and accretion vs. runaway explosion). The mass, velocity, and composition of outflows from the disk will be used in separate radiative transfer calculations to predict the lightcurves and spectra of the 56Ni-decay powered optical transients from WD-NS/WD-BH mergers. The possible connection of such events to recently discovered classes of sub-luminous Type I supernovae will be assessed. The coalescence of NS-NS/NS-BH binaries also results in the formation of a massive torus surrounding a central compact object. Three-dimensional magnetohydrodynamic simulations of the long-term evolution of such accretion disks will be performed, which for the first time follow the effects of weak interactions and the nuclear energy released by Helium recombination. The nucleosynthetic yield of disk outflows will be calculated using a detailed

  17. Magnetic fields of spherical compact stars in a braneworld

    SciTech Connect

    Ahmedov, B. J.; Fattoyev, F. J.

    2008-08-15

    We study the stellar magnetic field configuration in dependence on brane tension and present solutions of Maxwell equations in the external background space-time of a magnetized spherical star in a Randall-Sundrum II type braneworld. The star is modeled as a sphere consisting of perfect highly magnetized fluid with infinite conductivity and a frozen-in magnetic field. With respect to solutions for magnetic fields found in the Schwarzschild space-time, brane tension introduces enhancing corrections to the exterior magnetic field which could be relevant for the magnetic fields of magnetized compact objects as pulsars and magnetars and may provide observational evidence for the brane tension.

  18. Hans A. Bethe Prize: Mergers of Binary Compact Objects

    NASA Astrophysics Data System (ADS)

    Kalogera, Vassiliki

    2016-03-01

    The inspiral and eventual merger of two compact objects in binary systems are important in astrophysics across the electromagnetic spectrum and as potential gravitational-wave sources. In this talk I will select a few topics of current interest to highlight compact-object mergers, including in the context of multi-messenger astrophysics.

  19. Compact Translating-Head Magnetic Memories

    NASA Technical Reports Server (NTRS)

    Katti, Romney R.

    1992-01-01

    Stationary magnetic media stores information at densities up to 6.5 Gb/cm(Sup 2). High-density memory devices combine features of advanced rotating-disk magnetic recording and playback systems with compact two-axis high-acceleration linear actuators. New devices weigh less, occupy less space, and consume less power than disk and tape recorders.

  20. Electromagnetic Powers Of Merging And Collapsing Compact Objects

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2011-09-01

    Understanding possible EM signatures of the merging and collapsing compact object is important for identifying possible sources of LIGO & LISA signals. We estimate the electromagnetic powers that can be produced as a precursor to the merger, as a prompt emission during the collapse of a NS and at the spin-down stage of the resulting Kerr BH. In particular, we find exact non-linear time-dependent structure of magnetospheres of spinning and collapsing NSs in Schwarzschild geometry. Based on this solution, we argue that the collapse of a NS into the BH happens smoothly, without natural formation of current sheets or other dissipative structures on the open field lines and, thus, does not allow the magnetic field to become disconnected from the star and escape to infinity. Thus, as long as an isolated Kerr BH can produce plasma and currents, it does not lose its open magnetic field lines, its magnetospheric structure evolved towards a split monopole and the BH spins down electromagnetically (the closed field lines get absorbed by the hole). The "no hair theorem", which assumes that the outside medium is a vacuum, is not applicable in this case: highly conducting plasma introduces a topological constraint forbidding the disconnection of the magnetic field lines from the BH. Eventually, a single random large scale spontaneous reconnection event will lead to magnetic field release, shutting down the BH engine forever.

  1. Phase transformations in shock compacted magnetic materials

    NASA Astrophysics Data System (ADS)

    Wehrenberg, Christopher

    Shock compaction experiments were performed on soft magnetic phases Fe 4N and Fe16N2, and hard magnetic phases Nd 2Fe14B and Sm2Fe17N3 in order to determine their thermo-mechanical stability during shock loading and explore the possibility of fabricating a textured nanocomposite magnet. Gas gun experiments performed on powders pressed in a three capsule fixture showed phase transformations occurring in Fe4N, Fe16N 2, and Nd2Fe14B, while Sm2Fe17 N3 was observed to be relatively stable. Shock compaction of FCC Fe4N resulted in a partial transformation to HCP Fe3N, consistent with previous reports of the transition occurring at a static pressure of ~3 GPa. Shock compaction of Fe16N 2 produced decomposition products α-Fe, Fe4N, and FeN due to a combination of thermal effects associated with dynamic void collapse and plastic deformation. Decomposition of Nd-Fe-B, producing α-Fe and amorphous Nd-Fe-B, was observed in several shock consolidated samples and is attributed to deformation associated with shock compaction, similar to decomposition reported in ball milled Nd-Fe-B. No decomposition was observed in shock compacted samples of Sm-Fe-N, which is consistent with literature reports showing decomposition occurring only in samples compacted at a pressure above ~15 GPa. Nd-Fe-B and Sm-Fe-N were shown to accommodate deformation primarily by grain size reduction, especially in large grained materials. Hard/Soft composite magnetic materials were formed by mixing single crystal particles of Nd-Fe-B with iron nanoparticles, and the alignment-by-magnetic-field technique was able to introduce significant texture into green compacts of this mixture. While problems with decomposition of the Nd2Fe14B phase prevented fabricating bulk magnets from the aligned green compacts, retention of the nanoscale morphology of the α-Fe particles and the high alignment of the green compacts shows promise for future development of textured nanocomposite magnets through shock compaction.

  2. Compact Electric- And Magnetic-Field Sensor

    NASA Technical Reports Server (NTRS)

    Winterhalter, Daniel; Smith, Edward

    1994-01-01

    Compact sensor measures both electric and magnetic fields. Includes both short electric-field dipole and search-coil magnetometer. Three mounted orthogonally providing triaxial measurements of electromagnetic field at frequencies ranging from near 0 to about 10 kHz.

  3. Compaction dynamics of a magnetized powder.

    PubMed

    Lumay, G; Dorbolo, S; Vandewalle, N

    2009-10-01

    We have investigated experimentally the influence of a magnetic interaction between the grains on the compaction dynamics of a granular pile submitted to a series of taps. The granular material used to perform this study is a mixture of metallic and glass grains. The packing is immersed in homogeneous external magnetic field. The magnetic field induces an interaction between the metallic grains that constitutes the tunable cohesion. The compaction characteristic time and the asymptotic packing fraction have been measured as a function of the Bond number which is the ratio between the cohesive magnetic force and the grain weight. These measurements have been performed for different fractions of metallic beads in the pile. When the pile is only made of metallic grains, the characteristic compaction time increases as the square root of the Bond number. While the asymptotic packing fraction decreases as the inverse of the Bond number. For mixtures, when the fraction of magnetized grains in the pile is increased, the characteristic time increases while the asymptotic packing fraction decreases. A simple mesoscopic model based on the formation of granular chains along the magnetic field direction is proposed to explain the observed macroscopic properties of the packings. PMID:19905303

  4. Cold dark matter as compact composite objects

    NASA Astrophysics Data System (ADS)

    Zhitnitsky, Ariel

    2006-08-01

    Dark matter (DM) being the vital ingredient in the cosmos, still remains a mystery. The standard assumption is that the collisionless cold dark matter (CCDM) particles are represented by some weakly interacting fundamental fields which cannot be associated with any standard quarks or leptons. However, recent analyses of structure on galactic and subgalactic scales have suggested discrepancies and stimulated numerous alternative proposals including, e.g. self-interacting dark matter, self-annihilating dark matter, decaying dark matter, to name just a few. We propose the alternative to the standard assumption about the nature of DM particles (which are typically assumed to be weakly interacting fundamental pointlike particles, yet to be discovered). Our proposal is based on the idea that DM particles are strongly interacting composite macroscopically large objects which made of well-known light quarks (or even antiquarks). The required weakness of the DM particle interactions is guaranteed by a small geometrical factor γ˜(area)/(volume)˜B-1/3≪1 of the composite objects with a large baryon charge B≫1, rather than by a weak coupling constant of a new field. We argue that the interaction between hadronic matter and composite dark objects does not spoil the desired properties of the latter as cold matter. We also argue that such a scenario does not contradict to the current observational data. Rather, it has natural explanations of many observed data, such as ΩDM/ΩB˜1 or 511 KeV line from the bulge of our galaxy. We also suggest that composite dark matter may modify the dynamics of structure formation in the central overdense regions of galaxies. We also present a number of other cosmological/astrophysical observations which indirectly support the novel concept of DM nature.

  5. KEPLER OBSERVATIONS OF TRANSITING HOT COMPACT OBJECTS

    SciTech Connect

    Rowe, Jason F.; Borucki, William J.; Koch, David; Lissauer, Jack J.; Howell, Steve B.; Basri, Gibor; Marcy, Geoff; Batalha, Natalie; Brown, Timothy M.; Caldwell, Douglas; Jenkins, Jon; Cochran, William D.; Dunham, Edward; Dupree, Andrea K.; Latham, David W.; Sasselov, Dimitar; Fortney, Jonathan J.; Gautier, Thomas N.; Monet, David G.

    2010-04-20

    Kepler photometry has revealed two unusual transiting companions: one orbiting an early A-star and the other orbiting a late B-star. In both cases, the occultation of the companion is deeper than the transit. The occultation and transit with follow-up optical spectroscopy reveal a 9400 K early A-star, KOI-74 (KIC 6889235), with a companion in a 5.2 day orbit with a radius of 0.08 R {sub sun} and a 10,000 K late B-star KOI-81 (KIC 8823868) that has a companion in a 24 day orbit with a radius of 0.2 R {sub sun}. We infer a temperature of 12,250 K for KOI-74b and 13,500 K for KOI-81b. We present 43 days of high duty cycle, 30 minute cadence photometry, with models demonstrating the intriguing properties of these objects, and speculate on their nature.

  6. Electromagnetic power of merging and collapsing compact objects

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2011-06-01

    Understanding possible electromagnetic signatures of merging and collapsing compact objects is important for identifying possible sources of the LIGO signal. Electromagnetic emission can be produced as a precursor to the merger, as a prompt emission during the collapse of a neutron star and at the spin-down stage of the resulting Kerr-Newman black hole. For the neutron star-neutron star mergers, the precursor power scales as L≈BNS2GMNSRNS8/(Rorb7c), while for the neutron star-black hole mergers, it is (GM/(c2RNS))2 times smaller. We demonstrate that the time evolution of the axisymmetric force-free magnetic fields can be expressed in terms of the hyperbolic Grad-Shafranov equation, and we formulate the generalization of Ferraro’s law of isorotation to time-dependent angular velocity. We find an exact nonlinear time-dependent Michel-type (split-monopole) structure of magnetospheres driven by spinning and collapsing neutron stars in Schwarzschild geometry. Based on this solution, we argue that the collapse of a neutron star into a black hole happens smoothly, without the natural formation of current sheets or other dissipative structures on the open field lines; thus, it does not allow the magnetic field to become disconnected from the star and escape to infinity. Therefore, as long as an isolated Kerr black hole can produce plasma and currents, it does not lose its open magnetic field lines. Its magnetospheric structure evolves towards a split monopole, and the black hole spins down electromagnetically (the closed field lines get absorbed by the hole). The “no-hair theorem,” which assumes that the outside medium is a vacuum, is not applicable in this case: highly conducting plasma introduces a topological constraint forbidding the disconnection of the magnetic field lines from the black hole. Eventually, a single random large scale spontaneous reconnection event will lead to magnetic field release, shutting down the electromagnetic black hole engine forever

  7. Compact electrically detected magnetic resonance setup

    SciTech Connect

    Eckardt, Michael Harneit, Wolfgang; Behrends, Jan; Münter, Detlef

    2015-04-15

    Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a “large-scale” state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

  8. Compact electrically detected magnetic resonance setup

    NASA Astrophysics Data System (ADS)

    Eckardt, Michael; Behrends, Jan; Münter, Detlef; Harneit, Wolfgang

    2015-04-01

    Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a "large-scale" state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

  9. Dynamic magnetic compaction of porous materials

    SciTech Connect

    1998-10-29

    IAP Research began development of the Dynamic Magnetic Compaction (DMC) process three years before the CRADA was established. IAP Research had experimentally demonstrated the feasibility of the process, and conducted a basic market survey. IAP identified and opened discussions with industrial partners and established the basic commercial cost structure. The purpose of this CRADA project was to predict and verify optimum pressure vs. time history for the compaction of porous copper and tungsten. LLNL modeled the rapid compaction of powdered material from an initial density of about 30% theoretical maximum to more than 90% theoretical maximum. The compaction simulations were benchmarked against existing data and new data was acquired by IAP Research. The modeling was used to perform parameter studies on the pressure loading time history, initial porosity and temperature. LLNL ran simulations using codes CALE or NITO and compared the simulations with published compaction data and equation of state (EOS) data. This project did not involve the development or modification of software code. CALE and NITO were existing software programs at LLNL. No modification of these programs occurred within the scope of the CRADA effort.

  10. Evolution of binaries with compact objects in globular clusters

    NASA Astrophysics Data System (ADS)

    Ivanova, Natalia

    2016-02-01

    Dynamical interactions that take place between objects in dense stellar systems lead to frequent formation of exotic stellar objects, unusual binaries, and systems of higher multiplicity. They are most important for the formation of binaries with neutron stars and black holes, which are usually observationally revealed in mass-transferring binaries. Here we review the current understanding of compact object's retention, of the metallicity dependence on the formation of low-mass X-ray binaries with neutron stars, and how mass-transferring binaries with a black hole and a white dwarf can be formed. We discuss as well one old unsolved puzzle and two new puzzles posed by recent observations: what descendants do ultra-compact X-ray binaries produce, how are very compact triples formed, and how can black hole low-mass X-ray binaries acquire non-degenerate companions?

  11. Thermo-Rotational Instability in Plasma Disks Around Compact Objects*

    NASA Astrophysics Data System (ADS)

    Coppi, Bruno

    2008-04-01

    Differentially rotating plasma disks, around compact objects, that are imbedded in a ``seed'' magnetic field are shown to develop vertically localized ballooning modes that are driven by the combined radial gradient of the rotation frequency and the vertical gradients of the plasma density and temperature [1]. When the electron mean free path is shorter than the disk height and the (vertical) thermal conductivity can be neglected, the vertical particle flows produced by of these modes have the effect to drive the density and temperature profiles toward the ``adiabatic condition'' where ηT≡(dlnT/dz/(dlnn/dz)=2/3. Here T is the plasma temperature and n the particle density. The faster growth rates correspond to steeper temperature profiles (ηT>2/3) such as those produced by an internal (e.g. viscous) heating process. In the end, ballooning modes excited for various values of ηT can lead to the evolution of the disk into a different current carrying configuration such as a sequence of plasma rings[2].*Sponsored in part by the U.S. Department of Energy[1]B. Coppi, M.I.T. (LNS) Report HEP, 07/02, Cambridge, MA (2007), Invited Paper at the International Symposium on ``Momentum Transport in Jets, Disks and Laboratory Plasmas'', Alba, Piedmont, September 2007, to be published in Europhysical Letters (EPL, IOP)[2]B. Coppi andF. Rousseau, Ap. J., 641, 458, (2006)

  12. Dynamic Hysteresis in Compacted Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chowdary, Krishna M.

    The frequency and temperature dependent magnetic response of a bulk soft magnetic nanocomposite made by compacting Fe10Co 90 nanoparticles was measured and modeled. Electron microscopy and x-ray diffraction were used to characterize the size, composition, and structure of the nanoparticles and nanocomposite. Polyol synthesis was used to produce 200 nm particles with average grain size 20 nm and large superparamagnetic fraction. The nanoparticles were consolidated to 90% theoretical density by plasma pressure compaction. The compacted nanoparticles retained the 20 nm average grain size and large superparamagnetic fraction. The nanocomposite resistivity was more than three times that of the bulk alloy. Vibrating sample and SQUID-MPMS magnetometers were used for low frequency magnetic measurements of the nanoparticles and nanocomposite. Compaction reduced the coercivity from 175 Oe to 8 Oe and the effective anisotropy from 124 x 10 3 ergs/cc to 7.9 x 103 ergs/cc. These reductions were caused by increased exchange coupling between surface nanograins, consistent with predictions from the Random Anisotropy model. Varying degrees of exchange coupling existed within the nanocomposite, contributing to a distribution of energy barriers. A permeameter was used for frequency dependent magnetic measurements on a toroid cut from the nanocomposite. Complex permeability, coercivity, and power loss were extracted from dynamic minor hysteresis loops measured over a range of temperatures (77 K - 873 K) and frequencies (0.1 kHz - 100 kHz). The real and imaginary parts of the complex permeability spectrum showed asymmetries consistent with a distribution of energy barriers and high damping. When the complex permeability, power loss, and coercivity were scaled relative to the peak frequency of the imaginary permeability, all fell on universal curves. Various microscopic and macroscopic models for the complex permeability were investigated. The complex permeability was successfully fit

  13. What Are the Compact Central Objects in Supernova Remnants?

    NASA Astrophysics Data System (ADS)

    Graber, James

    2002-04-01

    Recent Chandra observations of the compact central objects in supernova remnants have shown puzzling results that do not seem to be consistent with either black holes or neutron stars. (See e.g. Pavlov, Sanwal, Garmire and Zavlin, astro-ph-0112322.) In particular, the inferred effective emitting surface is too small to be the entire surface of a neutron star, but too bright to be a black hole. We discuss the possibility that these compact objects might be red holes instead of black holes or neutron stars. Red holes, which occur in alternate theories of gravity, naturally predict both the greater brightness of the emissions and the smaller effective size of the emitting surface from a collapsed object of the appropriate mass.

  14. Compact Multitube Helicon Source with Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Chen, Francis F.; Torreblanca, Humberto

    2006-10-01

    In spite of their efficiency, helicon sources are not readily adopted by industry because they require a large, heavy electromagnet and its power supply. Annular permanent magnets can create the B-field compactly and cheaply, but only if the plasma is placed outside the magnet in its remote field, so that the internal field lines do not carry the plasma into the wall. An 8-tube array of such sources has been constructed and tested. The size and shape of each tube was optimized by computation. The source can be extended to provide uniform densities of order 10^12 cm-3 over an arbitrarily large substrate. This source, which requires only six inches of height above the processing chamber, would be useful for web-coating, optical coating, and etching of flat-panel displays and solar cells.

  15. Gravitational effects of condensate dark matter on compact stellar objects

    SciTech Connect

    Li, X.Y.; Wang, F.Y.; Cheng, K.S. E-mail: fayinwang@gmail.com

    2012-10-01

    We study the gravitational effect of non-self-annihilating dark matter on compact stellar objects. The self-interaction of condensate dark matter can give high accretion rate of dark matter onto stars. Phase transition to condensation state takes place when the dark matter density exceeds the critical value. A compact degenerate dark matter core is developed and alter the structure and stability of the stellar objects. Condensate dark matter admixed neutron stars is studied through the two-fluid TOV equation. The existence of condensate dark matter deforms the mass-radius relation of neutron stars and lower their maximum baryonic masses and radii. The possible effects on the Gamma-ray Burst rate in high redshift are discussed.

  16. Studies of compact objects with Einstein - Review and prospects

    NASA Technical Reports Server (NTRS)

    Grindlay, Jonathan E.

    1990-01-01

    X-ray images and spectra of a wide range of systems containing compact objects were obtained with the Einstein X-ray Observatory. Accreting white dwarfs, neutron stars and black holes were observed in binary systems in the Galaxy, and new constraints were derived for their formation, nature and evolution. Massive black holes were studied in active galactic nuclei, and X-ray spectra (and evolution) of AGN have led to a new model for the diffuse X-ray background.

  17. Holographic equations of state and astrophysical compact objects

    NASA Astrophysics Data System (ADS)

    Kim, Youngman; Lee, Chang-Hwan; Shin, Ik Jae; Wan, Mew-Bing

    2011-10-01

    We solve the Tolman-Oppenheimer-Volkoff equation using an equation of state (EoS) calculated in holographic QCD. The aim is to use compact astrophysical objects like neutron stars as an indicator to test holographic equations of state. We first try an EoS from a dense D4/D8/D8 model. In this case, however, we could not find a stable compact star, a star satisfying pressure-zero condition with a radius R, p( R) = 0, within a reasonable value of the radius. This means that the EoS from the D4/D8/D8 model may not support any stable compact stars or may support one whose radius is very large. This might be due to a deficit of attractive force from a scalar field or two-pion exchange in the D4/D8/D8 model. Then, we consider D4/D6 type models with different number of quark flavors, N f = 1 , 2 , 3. Though the mass and radius of a holographic star is larger than those of normal neutron stars, the D4/D6 type EoS renders a stable compact star.

  18. Detection, classification, and tracking of compact objects in video imagery

    NASA Astrophysics Data System (ADS)

    Carlotto, Mark J.; Nebrich, Mark A.

    2012-06-01

    A video data conditioner (VDC) for automated full-­motion video (FMV) detection, classification, and tracking is described. VDC extends our multi-­stage image data conditioner (IDC) to video. Key features include robust detection of compact objects in motion imagery, coarse classification of all detections, and tracking of fixed and moving objects. An implementation of the detection and tracking components of the VDC on an Apple iPhone is discussed. Preliminary tracking results of naval ships captured during the Phoenix Express 2009 Photo Exercise are presented.

  19. Compact objects from gravitational collapse: an analytical toy model

    NASA Astrophysics Data System (ADS)

    Malafarina, Daniele; Joshi, Pankaj S.

    2015-12-01

    We develop here a procedure to obtain regular static configurations resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.

  20. The dynamic ejecta of compact object mergers and eccentric collisions.

    PubMed

    Rosswog, Stephan

    2013-06-13

    Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the 'heavy' (A>130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta ('macronovae'), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium. PMID:23630377

  1. Compact real-time image processor for moving object tracking

    NASA Astrophysics Data System (ADS)

    Kinoshita, Noboru

    1996-03-01

    Latency time and hardware compactness are two important problems of real-time image processors for moving object tracking. We have developed a compact self-contained real-time image processor that is implemented on a single double-height VME board. The processor can execute major processing steps for moving object tacking during a single video field time. These steps are preprocessing, binarizing, labeling, feature extraction, and feature evaluation. We can obtain sorted feature vectors simultaneously when image data is read out from a sensor. Here a feature vector represents areas, centroid, and maximum intensity of each connected region in a binarized image. Some conventional image processors can execute the above steps individually in real-time and thread some steps in a pixel pipeline manner. However it is difficult to integrate feature extraction and feature evaluation in a pixel pipeline path. For real-time execution of all steps we focused on new architecture particularly for the latter three steps. To minimize the hardware we have developed three ASICs: labeler, feature accumulator, and sorter. To make our processor self-contained and scalable, it has an on- board micro processor, a digital video bus interface, and an RS232C port, and it is VME compatible in bus interface and mechanical dimension.

  2. Electromagnetic field and cylindrical compact objects in modified gravity

    NASA Astrophysics Data System (ADS)

    Yousaf, Z.; Bhatti, M. Zaeem ul Haq

    2016-05-01

    In this paper, we have investigated the role of different fluid parameters particularly electromagnetic field and f(R) corrections on the evolution of cylindrical compact object. We have explored the modified field equations, kinematical quantities and dynamical equations. An expression for the mass function has been found in comparison with the Misner-Sharp formalism in modified gravity, after which different mass-radius diagrams are drawn. The coupled dynamical transport equation have been formulated to discuss the role of thermoinertial effects on the inertial mass density of the cylindrical relativistic interior. Finally, we have presented a framework, according to which all possible solutions of the metric f(R)-Maxwell field equations coupled with static fluid can be written through set of scalar functions. It is found that modified gravity induced by Lagrangians f(R) = αR2, f(R) = αR2 - βR and f(R)=α R^2-β R/1+γ R are likely to host more massive cylindrical compact objects with smaller radii as compared to general relativity.

  3. The Fate of Fallback Matter around Newly Born Compact Objects

    NASA Astrophysics Data System (ADS)

    Perna, Rosalba; Duffell, Paul; Cantiello, Matteo; MacFadyen, Andrew I.

    2014-02-01

    The presence of fallback disks around young neutron stars (NSs) has been invoked over the years to explain a large variety of phenomena. Here we perform a numerical investigation of the formation of such disks during a supernova (SN) explosion, considering both NS and black hole (BH) remnants. Using the public code MESA, we compute the angular momentum distribution of the pre-SN material, for stars with initial masses M in the range 13-40 M ⊙, initial surface rotational velocities v surf between 25% and 75% of the critical velocity, and for metallicities Z of 1%, 10%, and 100% of the solar value. These pre-SN models are exploded with energies E varying between 1050-3 × 1052 erg, and the amount of fallback material is computed. We find that, if magnetic torques play an important role in angular momentum transport, then fallback disks around NSs, even for low-metallicity main-sequence stars, are not an outcome of SN explosions. Formation of such disks around young NSs can only happen under the condition of negligible magnetic torques and a fine-tuned explosion energy. For those stars that leave behind BH remnants, disk formation is ubiquitous if magnetic fields do not play a strong role; however, unlike the NS case, even with strong magnetic coupling in the interior, a disk can form in a large region of the Z, M, v surf, E parameter space. Together with the compact, hyperaccreting fallback disks widely discussed in the literature, we identify regions in the above parameter space that lead to extended, long-lived disks around BHs. We find that the physical conditions in these disks may be conducive to planet formation, hence leading to the possible existence of planets orbiting BHs.

  4. Electromagnetic Counterparts of Gravitational Wave Sources: Mergers of Compact Objects

    NASA Astrophysics Data System (ADS)

    Kamble, Atish; Kaplan, David L. A.

    2013-01-01

    Mergers of compact objects are considered prime sources of gravitational waves (GW) and will soon be targets of GW observatories such as the Advanced-LIGO and VIRGO. Finding electromagnetic counterparts of these GW sources will be important to understand their nature. We discuss possible electromagnetic signatures of the mergers. We show that the BH-BH mergers could have luminosities which exceed Eddington luminosity from unity to several orders of magnitude depending on the masses of the merging BHs. As a result these mergers could be explosive, release up to 1051 erg of energy and shine as radio transients. At any given time we expect about a few such transients in the sky at GHz frequencies, which could be detected to be about 300 Mpc. It has also been argued that these radio transients would look alike radio supernovae with comparable detection rates. Multi-band follow-up could, however, distinguish between the mergers and supernovae.

  5. Casimir potential of a compact object enclosed by a spherical cavity

    SciTech Connect

    Zaheer, Saad; Rahi, Sahand Jamal; Emig, Thorsten; Jaffe, Robert L.

    2010-11-15

    We study the electromagnetic Casimir interaction of a compact object contained inside a closed cavity of another compact object. We express the interaction energy in terms of the objects' scattering matrices and translation matrices that relate the coordinate systems appropriate to each object. When the enclosing object is an otherwise empty metallic spherical shell, much larger than the internal object, and the two are sufficiently separated, the Casimir force can be expressed in terms of the static electric and magnetic multipole polarizabilities of the internal object, which is analogous to the Casimir-Polder result. Although it is not a simple power law, the dependence of the force on the separation of the object from the containing sphere is a universal function of its displacement from the center of the sphere, independent of other details of the object's electromagnetic response. Furthermore, we compute the exact Casimir force between two metallic spheres contained one inside the other at arbitrary separations. Finally, we combine our results with earlier work on the Casimir force between two spheres to obtain data on the leading-order correction to the proximity force approximation for two metallic spheres both outside and within one another.

  6. Evidence for a binary origin of a central compact object

    NASA Astrophysics Data System (ADS)

    Doroshenko, Victor; Pühlhofer, Gerd; Kavanagh, Patrick; Santangelo, Andrea; Suleimanov, Valery; Klochkov, Dmitry

    2016-05-01

    Central compact objects (CCOs) are thought to be young thermally emitting isolated neutron stars that were born during the preceding core-collapse supernova explosion. Here, we present evidence that at least in one case the CCO could have been formed within a binary system. We show that the highly reddened optical source IRAS 17287-3443, located 25 arcsec away from the CCO candidate XMMUJ173203.3-344518 and classified previously as a post asymptotic giant branch star, is indeed surrounded by a dust shell. This shell is heated by the central star to temperatures of ˜90 K and observed as extended infrared emission in 8-160 μm band. The dust temperature also increases in the vicinity of the CCO which implies that it likely resides within the shell. We estimate the total dust mass to be ˜0.4-1.5 M⊙ which significantly exceeds expected dust yields by normal stars and thus likely condensed from supernova ejecta. Taking into account that both the age of the supernova remnant and the duration of active mass-loss phase by the optical star are much shorter than the total lifetime of either object, the supernova and the onset of the active mass-loss phase of the companion have likely occurred approximately simultaneously. This is most easily explained if the evolution of both objects is interconnected. We conclude, therefore, that both stars were likely members of the same binary system disrupted by a supernova.

  7. Super-spinning compact objects generated by thick accretion disks

    SciTech Connect

    Li, Zilong; Bambi, Cosimo E-mail: bambi@fudan.edu.cn

    2013-03-01

    If astrophysical black hole candidates are the Kerr black holes predicted by General Relativity, the value of their spin parameter must be subject to the theoretical bound |a{sub *}| ≤ 1. In this work, we consider the possibility that these objects are either non-Kerr black holes in an alternative theory of gravity or exotic compact objects in General Relativity. We study the accretion process when their accretion disk is geometrically thick with a simple version of the Polish doughnut model. The picture of the accretion process may be qualitatively different from the one around a Kerr black hole. The inner edge of the disk may not have the typical cusp on the equatorial plane any more, but there may be two cusps, respectively above and below the equatorial plane. We extend previous work on the evolution of the spin parameter and we estimate the maximum value of a{sub *} for the super-massive black hole candidates in galactic nuclei. Since measurements of the mean radiative efficiency of AGNs require η > 0.15, we infer the ''observational'' bound |a{sub *}|∼<1.3, which seems to be quite independent of the exact nature of these objects. Such a bound is only slightly weaker than |a{sub *}|∼<1.2 found in previous work for thin disks.

  8. Central Compact Objects in Kes 79 and RCW 103 as `Hidden' Magnetars with Crustal Activity

    NASA Astrophysics Data System (ADS)

    Popov, S. B.; Kaurov, A. A.; Kaminker, A. D.

    2015-05-01

    We propose that observations of `hidden' magnetars in central compact objects can be used to probe crustal activity of neutron stars with large internal magnetic fields. Estimates based on calculations by Perna & Pons, Pons & Rea and Kaminker et al. suggest that central compact objects, which are proposed to be `hidden' magnetars, must demonstrate flux variations on the time scale of months-years. However, the most prominent candidate for the `hidden' magnetars - CXO J1852.6+0040 in Kes 79 - shows constant (within error bars) flux. This can be interpreted by lower variable crustal activity than in typical magnetars. Alternatively, CXO J1852.6+0040 can be in a high state of variable activity during the whole period of observations. Then we consider the source 1E161348 - 5055 in RCW103 as another candidate. Employing a simple 2D-modelling we argue that properties of the source can be explained by the crustal activity of the magnetar type. Thus, this object may be supplemented for the three known candidates for the `hidden' magnetars among central compact objects discussed in literature.

  9. Tidal torque induced by orbital decay in compact object binaries

    NASA Astrophysics Data System (ADS)

    Dall'Osso, Simone; Rossi, Elena M.

    2013-01-01

    As we observe in the moon-earth system, tidal interactions in binary systems can lead to angular momentum exchange. The presence of viscosity is generally regarded as the condition for such transfer to happen. In this paper, we show how the orbital evolution can cause a persistent torque between the binary components, even for inviscid bodies. This preferentially occurs at the final stage of coalescence of compact binaries, when the orbit shrinks successively by gravitational waves and plunging on a time-scale shorter than the viscous time-scale. The total orbital energy transferred to the secondary by this torque is ˜10-2 of its binding energy. We further show that this persistent torque induces a differentially rotating quadrupolar perturbation. Specializing to the case of a secondary neutron star, we find that this non-equilibrium state has an associated free energy of 1047-1048 erg, just prior to coalescence. This energy is likely stored in internal fluid motions, with a sizeable amount of differential rotation. By tapping this free energy reservoir, a pre-existing weak magnetic field could be amplified up to a strength of ≈1015 G. Such a dynamically driven tidal torque can thus recycle an old neutron star into a magnetar, with possible observational consequences at merger.

  10. Recent developments in the tidal deformability of spinning compact objects

    NASA Astrophysics Data System (ADS)

    Pani, Paolo; Gualtieri, Leonardo; Maselli, Andrea; Ferrari, Valeria

    2016-04-01

    We review recent work on the theory of tidal deformability and the tidal Love numbers of a slowly spinning compact object within general relativity. Angular momentum introduces couplings between distortions of different parity and new classes of spin-induced, tidal Love numbers emerge. Due to spin-tidal effects, a rotating object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second-order in the spin. The tidal Love numbers depend strongly on the object’s internal structure. All tidal Love numbers of a Kerr black hole (BH) were proved to be exactly zero to first-order in the spin and also to second-order in the spin, at least in the axisymmetric case. For a binary system close to the merger, various components of the tidal field become relevant. Preliminary results suggest that spin-tidal couplings can introduce important corrections to the gravitational waveforms of spinning neutron star (NS) binaries approaching the merger.

  11. DOUBLE COMPACT OBJECTS AS LOW-FREQUENCY GRAVITATIONAL WAVE SOURCES

    SciTech Connect

    Belczynski, Krzysztof; Bulik, Tomasz; Benacquista, Matthew

    2010-12-10

    We study the Galactic field population of double compact objects (DCOs; NS-NS, BH-NS, BH-BH binaries) to investigate the number (if any) of these systems that can potentially be detected with the Laser Interferometer Space Antenna (LISA) at low gravitational wave frequencies. We calculate the Galactic numbers and physical properties of these binaries and show their relative contributions from the disk, bulge, and halo. Although the Galaxy hosts {approx}10{sup 5} DCO binaries emitting low-frequency gravitational waves, only a handful of these objects in the disk will be detectable with LISA, but none from the halo or bulge. This is because the bulk of these binaries are NS-NS systems with high eccentricities and long orbital periods (weeks/months) causing inefficient signal accumulation (a small number of signal bursts at periastron passage in one year of LISA observations) and rendering them undetectable in the majority of these cases. We adopt two evolutionary models that differ in their treatment of the common envelope (CE) phase that is a major (and still mostly unknown) process in the formation of close DCOs. Depending on the evolutionary model adopted, our calculations indicate the likely detection of about four NS-NS binaries and two BH-BH systems (model A; likely survival of progenitors through CE) or only a couple of NS-NS binaries (model B; suppression of the DCO formation due to CE mergers).

  12. A Central Compact Object in Kes 79: The hypercritical regime and neutrino expectation

    NASA Astrophysics Data System (ADS)

    Bernal, C. G.; Fraija, N.

    2016-08-01

    We present magnetohydrodynamical simulations of a strong accretion onto magnetized proto-neutron stars for the Kesteven 79 (Kes 79) scenario. The supernova remnant Kes 79, observed with the Chandra ACIS-I instrument during approximately 8.3 h, is located in the constellation Aquila at a distance of 7.1 kpc in the galactic plane. It is a galactic and a very young object with an estimate age of 6 kyr. The Chandra image has revealed, for the first time, a point-like source at the center of the remnant. The Kes 79 compact remnant belongs to a special class of objects, the so-called Central Compact Objects, which exhibits no evidence for a surrounding pulsar wind nebula. In this work we show that the submergence of the magnetic field during the hypercritical phase can explain such behavior for Kes 79 and others CCOs. The simulations of such regime were carried out with the adaptive-mesh-refinement code FLASH in two spatial dimensions, including radiative loss by neutrinos and an adequate equation of state for such regime. From the simulations, we estimate that the number of thermal neutrinos expected on the Hyper-Kamiokande Experiment is 733±364. In addition, we compute the flavor ratio on Earth for a progenitor model.

  13. Gluon Vortices and Induced Magnetic Field in Compact Stars

    SciTech Connect

    Ferrer, Efrain J.

    2007-10-26

    The natural candidates for the realization of color superconductivity are the extremely dense cores of compact stars, many of which have very large magnetic fields, especially the so called magnetars. In this paper we discuss how a color superconducting core can serve to generate and enhance the stellar magnetic field without appealing to a magnetohydrodynamic dynamo mechanism.

  14. Shock compaction of magnet powder using underwater shock wave

    SciTech Connect

    Kubota, Shiro; Fujita, Masahiro; Itoh, Shigeru

    1996-12-31

    In order to get a high plug density (over 90%), the authors tried a direct consolidation of the magnet powder using the converging underwater shock wave created by the underwater explosion of explosives. The processes of the consolidation of the magnet powder were investigated by numerical calculation. They obtained the parameters of the EOS (Petrie-Page model) for Magnet powder using quasi-static loading experiments. Moreover, the characteristics of the shock compaction assembly were also verified.

  15. Using magnetic nanoparticles to manipulate biological objects

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Gao, Yu; Xu, Chenjie

    2013-09-01

    The use of magnetic nanoparticles (MNPs) for the manipulation of biological objects, including proteins, genes, cellular organelles, bacteria, cells, and organs, are reviewed. MNPs are popular candidates for controlling and probing biological objects with a magnetic force. In the past decade, progress in the synthesis and surface engineering of MNPs has further enhanced this popularity.

  16. BINARY COMPACT OBJECT COALESCENCE RATES: THE ROLE OF ELLIPTICAL GALAXIES

    SciTech Connect

    O'Shaughnessy, R.; Kalogera, V.; Belczynski, Krzysztof E-mail: vicky@northwestern.ed

    2010-06-10

    In this paper, we estimate binary compact object merger detection rates for LIGO, including the potentially significant contribution from binaries that are produced in elliptical galaxies near the epoch of peak star formation. Specifically, we convolve hundreds of model realizations of elliptical- and spiral-galaxy population syntheses with a model for elliptical- and spiral-galaxy star formation history as a function of redshift. Our results favor local merger rate densities of 4 x 10{sup -3} Mpc{sup -3} Myr{sup -1} for binary black holes (BHs), 3 x 10{sup -2} Mpc{sup -3} Myr{sup -1} for binary neutron stars (NSs), and 10{sup -2} Mpc{sup -3} Myr{sup -1} for BH-NS binaries. We find that mergers in elliptical galaxies are a significant fraction of our total estimate for BH-BH and BH-NS detection rates; NS-NS detection rates are likely dominated by the contribution from spiral galaxies. Limiting attention to elliptical-galaxy plus only those spiral-galaxy models that reproduce current observations of Galactic NS-NS, we find slightly higher rates for NS-NS and largely similar ranges for BH-NS and BH-BH binaries. Assuming a detection signal-to-noise ratio threshold of 8 for a single detector (in practice as part of a network, to reduce its noise), corresponding to radii D {sub bns} of the effective volume inside of which a single LIGO detector could observe the inspiral of two 1.4 M {sub sun} NSs of 14 Mpc and 197 Mpc, for initial and advanced LIGO, we find event rates of any merger type of 2.9 x 10{sup -2}-0.46 and 25-400 yr{sup -1} (at 90% confidence level), respectively. We also find that the probability P {sub detect} of detecting one or more mergers with this single detector can be approximated by (1) P {sub detect} {approx_equal} 0.4 + 0.5 log(T/0.01 yr), assuming D {sub bns} = 197 Mpc and it operates for T yr, for T between 2 days and 0.1 yr, or by (2) P {sub detect} {approx_equal} 0.5 + 1.5 log(D {sub bns}/32 Mpc), for 1 yr of operation and for D {sub bns

  17. An X-ray View of the Zoo of Compact Objects and Associated Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Safi-Harb, Samar

    2015-08-01

    Core-collapse explosions of massive stars leave behind some of the most exotic compact objects in the Universe. These include: rotation-powered pulsars like the Crab, powering pulsar wind nebulae (PWNe) observed across the electromagnetic spectrum; highly magnetized neutron stars ("magnetars") shining or bursting at high-energies; and X-ray emitting “Central Compact Objects” (CCOs) with intrinsic properties and emission mechanism that remain largely unknown. I will highlight this observed diversity of compact stellar remnants from an X-ray perspective, and address the connection between their properties and those of their hosting supernova remnants (SNRs). In particular I will highlight topics related to their formation and evolution, including: 1) which supernovae make magnetars and the shell-less PWNe?, 2) what can we learn from the apparent age discrepancy between SNRs and their associated pulsars? I will conclude with prospects for observations of SNRs with the upcoming ASTRO-H X-ray mission. The unprecedented spectral resolution on board of ASTRO-H’s micro-calorimeter will particularly open a new discovery window for supernova progenitors' science.

  18. A Compact High Gradient Pulsed Magnetic Quadpole

    SciTech Connect

    Shuman, D.; Faltens, A.; Kajiyama, Y.; Kireeff-Covo, M.; Seidl, P.

    2005-07-05

    A design for a high gradient, low inductance pulsed quadrupole magnet is presented. The magnet is a circular current dominated design with a circular iron return yoke. Conductor angles are determined by a method of direct multipole elimination which theoretically eliminates the first four higher order multipole field components. Coils are fabricated from solid round film-insulated conductor, wound as a single layer ''non-spiral bedstead'' coil having a diagonal leadout entirely within one upturned end. The coils are wound and stretched straight in a special winder, then bent in simple fixtures to form the upturned ends.

  19. Evolution of photon and particle spectra in compact, luminous objects

    NASA Technical Reports Server (NTRS)

    Eilek, Jean A.; Caroff, Lawrence J.; Noerdlinger, Peter D.

    1988-01-01

    The physics of high energy photons and particles (especially electrons and positrons) in the compact, high-energy-density of galactic nuclei and quasars was investigated. A numerical code was developed which follows the nonlinear spectral evolution of a pair/photon plasma, due to two-body scattering and interaction process, in an unmagnetized system. The code was applied both to static plasmas and to relativistic expanding winds.

  20. Construction of CHESS compact undulator magnets at Kyma

    NASA Astrophysics Data System (ADS)

    Temnykh, Alexander B.; Lyndaker, Aaron; Kokole, Mirko; Milharcic, Tadej; Pockar, Jure; Geometrante, Raffaella

    2015-05-01

    In 2014 KYMA S.r.l. has built two CHESS Compact Undulator (CCU) magnets that are at present installed and successfully operate at the Cornell Electron Storage Ring. This type of undulator was developed for upgrade of Cornell High Energy Synchrotron Source beam-lines, but it can be used elsewhere as well. CCU magnets are compact, lightweight, cost efficient and in-vacuum compatible. They are linearly polarized undulators and have a fixed gap. Magnetic field tuning is achieved by phasing (shifting) top magnetic array relative bottom. Two CCUs constructed by KYMA S.r.l. have 28.4 mm period, 6.5 mm gap, 0.93 T peak field. Magnetic structure is of PPM type, made with NdFeB (40UH grade) permanent magnet material. Transitioning from the laboratory to industrial environment for a novel design required additional evaluation, design adjusting and extensive testing. Particular attention was given to the soldering technique used for fastening of the magnetic blocks to holders. This technique had thus far never been used before for undulator magnet construction by industry. The evaluation included tests of different types of soldering paste, measurements of strength of solder and determining the deformations of the soldered magnet and holder under simulated loading forces. This paper focuses on critical features of the CCU design, results of the soldering technique testing and the data regarding permanent magnets magnetization change due to soldering. In addition it deals with optimization-assisted assembly and the performance of the assembled devices and assesses some of the results of the CCU magnets operation at CESR.

  1. Magnetic Bunch Compression for a Compact Compton Source

    SciTech Connect

    Gamage, B.; Satogata, Todd J.

    2013-12-01

    A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. Here we discuss two options for transverse magnetic bunch compression and final focus, each involving a 4-dipole chicane with M_{56} tunable over a range of 1.5-2.0m with independent tuning of final focus to interaction point $\\beta$*=5mm. One design has no net bending, while the other has net bending of 90 degrees and is suitable for compact corner placement.

  2. Packing fraction and compaction dynamics of magnetic powders

    NASA Astrophysics Data System (ADS)

    Lumay, G.; Vandewalle, N.

    2009-06-01

    We have investigated experimentally the influence of magnetic interactions between the grains (i) on the packing fraction and (ii) on the compaction dynamics of a granular pile. The granular material used to perform these studies is made of ferromagnetic grains submitted to an external magnetic field B⃗. The evolution of the packing fraction as a function of the Bond number Bo witch is the ratio between the cohesive force Fc and the grain weight mg has been measured. Moreover, we present an experimental protocol that allows one to tune the packing fraction η of a random pile of ferromagnetic spheres from a value close to the lower limit of random loose packing ηRLP≃0.56 to the upper limit of random close packing ηRCP≃0.64. This broad range of packing fraction values are obtained under normal gravity in air, by using a magnetic cohesion between the grains during the initialization of the pile. Concerning the compaction dynamics, the influence of the magnetic interaction on the compaction characteristic time τ has been measured.

  3. Magnetic levitation system for moving objects

    DOEpatents

    Post, R.F.

    1998-03-03

    Repelling magnetic forces are produced by the interaction of a flux-concentrated magnetic field (produced by permanent magnets or electromagnets) with an inductively loaded closed electric circuit. When one such element moves with respect to the other, a current is induced in the circuit. This current then interacts back on the field to produce a repelling force. These repelling magnetic forces are applied to magnetically levitate a moving object such as a train car. The power required to levitate a train of such cars is drawn from the motional energy of the train itself, and typically represents only a percent or two of the several megawatts of power required to overcome aerodynamic drag at high speeds. 7 figs.

  4. Magnetic levitation system for moving objects

    DOEpatents

    Post, Richard F.

    1998-01-01

    Repelling magnetic forces are produced by the interaction of a flux-concentrated magnetic field (produced by permanent magnets or electromagnets) with an inductively loaded closed electric circuit. When one such element moves with respect to the other, a current is induced in the circuit. This current then interacts back on the field to produce a repelling force. These repelling magnetic forces are applied to magnetically levitate a moving object such as a train car. The power required to levitate a train of such cars is drawn from the motional energy of the train itself, and typically represents only a percent or two of the several megawatts of power required to overcome aerodynamic drag at high speeds.

  5. Strange Stars : An interesting member of the compact object family

    SciTech Connect

    Bagchi, Manjari; Ray, Subharthi; Dey, Jishnu; Dey, Mira

    2008-01-10

    We have studied strange star properties both at zero temperature and at finite temperatures and searched signatures of strange stars in gamma-ray, x-ray and radio astronomy. We have a set of Equations of State (EoS) for strange quark matter (SQM) and solving the TOV equations, we get the structure of strange stars. The maximum mass for a strange star decreases with the increase of temperature, because at high temperatures, the EoS become softer. One important aspect of strange star is that, surface tension depends on the size and structure of the star and is significantly larger than the conventional values. Moment of inertia is another important parameter for compact stars as by comparing theoretical values with observed estimate, it is possible to constrain the dense matter Equation of State. We hope that this approach will help us to decide whether the members of the double pulsar system PSR J0737-3039 are neutron stars or strange stars.

  6. Modeling and detecting gravitational waves from compact stellar objects

    NASA Astrophysics Data System (ADS)

    Vallisneri, Michele

    In the next few years, the first detections of gravity- wave signals using Earth-based interferometric detectors will begin to provide precious new information about the structure, dynamics, and evolution of compact bodies, such as neutron stars and black holes, both isolated and in binary systems. The intrinsic weakness of gravity-wave signals requires a proactive approach to modeling the prospective sources and anticipating the shape of the signals that we seek to detect. Full-blown 3-D numerical simulations of the sources are playing and will play an important role in planning the gravity-wave data-analysis effort. This thesis explores the interplay between numerical source modeling and data analysis, looking closely at three case studies. (1)I evaluate the prospects for extracting equation-of-state information from neutron-star tidal disruption in neutron-star-black- hole binaries with LIGO-II, and I estimate that the observation of disrupting systems at distances that yield about one event per year should allow the determination of the neutron-star radius to about 15%, which compares favorably to the currently available electromagnetic determinations. (2)In collaboration with Lee Lindblom and Joel Tohline, I perform numerical simulations of the nonlinear dynamics of the r-mode instability in young, rapidly spinning neutron stars, and I find evidence that nonlinear couplings to other modes will not pose a significant limitation to the growth of the r-mode amplitude. (3)In collaboration with Alessandra Buonanno and Yanbei Chen, I study the problem of detecting gravity waves from solar-mass black-hole - black-hole binaries with LIGO-I, and I construct two families of detection templates that address the inadequacy of standard post-Newtonian theory to predict reliable waveforms for these systems.

  7. Compact and extended objects from self-interacting phantom fields

    NASA Astrophysics Data System (ADS)

    Dzhunushaliev, Vladimir; Folomeev, Vladimir; Makhmudov, Arislan; Urazalina, Ainur; Singleton, Douglas; Scott, John

    2016-07-01

    In this work, we investigate localized and extended objects for gravitating, self-interacting phantom fields. The phantom fields come from two scalar fields with a "wrong-sign" (negative) kinetic energy term in the Lagrangian. This study covers several solutions supported by these phantom fields: phantom balls, traversable wormholes, phantom cosmic strings, and "phantom" domain walls. These four systems are solved numerically, and we try to draw out general, interesting features in each case.

  8. Extremely red compact radio sources - The empty field objects

    NASA Technical Reports Server (NTRS)

    Beichman, C. A.; Neugebauer, G.; Soifer, B. T.; Matthews, K.; Wootten, H. A.; Pravdo, S. H.

    1981-01-01

    Radiation of 10 microns has been detected from 1413+135, one of the very red objects discovered by Rieke, Lebofsky, and Kinman (1979) at near-infrared wavelengths. The spectrum of this object flattens at wavelengths longer than 2.2 microns. Upper limits are also given for the 10-micron emission from 2255+14, 0026+34, and 0406+121. Photometry between 1.25 and 2.2 microns confirms the variability of 1413+135, 2255+41, and 0406+121. Five percent resolution spectra of 1413+135 and 0406+121 between 1.5 and 2.4 microns show no emission or absorption lines. The spectral data rule out the possibility that 1413+135 is a quasar with normal line strengths and a redshift less than 1.3 and greater than 4. The lack of features of the 1.5-2.4-micron spectra, the rapid variability, and the overall shape of the radio, infrared, and X-ray energy distributions are consistent with a BL Lac nature for these objects.

  9. Compacted Co(Fe)-Coated Sm-Co Nanocomposite Magnets

    NASA Astrophysics Data System (ADS)

    Zeng, Qi; Zhang, Yong; Hadjipananyis, George C.

    2003-03-01

    One of the big challenges in nanocomposite magnets is to develop a synthesis route that produces a structure in which all the nanograins are crystallographically aligned. In this study, we use the novel consolidation technique of Plasma Pressure Compaction (PPC) to prepare bulk SmCo/Co(Fe) nanocomposite magnets. SmCo/Co and SmCo/FeCo nanocomposites have been fabricated by electroless plating magnetically soft nano-size Co and Co-Fe particles on the surface of micron-size hard Sm-Co powders. The influence of electroless plating conditions on the magnetic properties and structure of the coating were studied. The magnetic saturation and morphology of the deposited material were found to be dependent on the concentration of reducing agent, temperature of the solution and plating time. For 50 µm Sm(Co,Cu,Fe,Zr)7.5 particles, coating with Co has had a little effect on the coercivity maintaining a level of 7 kOe while there is a increase in the value of MS depending on Co plating time. In SmCo5 particles with a size of several microns, coating with Co alloy, Hc decreases and saturation magnetization increases with increasing plating time, but the loops remain smooth. The effect of PPC on the microstructure, the magnetic properties of exchange coupled magnets will be discussed. Work supported by DARPA-Meta-Materials Program (No. F33615-01-2-2166).

  10. CONSTRAINING THE EVOLUTIONARY FATE OF CENTRAL COMPACT OBJECTS: ''OLD'' RADIO PULSARS IN SUPERNOVA REMNANTS

    SciTech Connect

    Bogdanov, Slavko; Ng, C.-Y.; Kaspi, Victoria M.

    2014-09-10

    Central compact objects (CCOs) constitute a population of radio-quiet, slowly spinning (≥100 ms) young neutron stars with anomalously high thermal X-ray luminosities. Their spin-down properties imply weak dipole magnetic fields (∼10{sup 10-11} G) and characteristic ages much greater than the ages of their host supernova remnants (SNRs). However, CCOs may posses strong ''hidden'' internal magnetic fields that may re-emerge on timescales of ≳10 kyr, with the neutron star possibly activating as a radio pulsar in the process. This suggests that the immediate descendants of CCOs may be masquerading as slowly spinning ''old'' radio pulsars. We present an X-ray survey of all ordinary radio pulsars within 6 kpc that are positionally coincident with Galactic SNRs in order to test the possible connection between the supposedly old but possibly very young pulsars and the SNRs. None of the targets exhibit anomalously high thermal X-ray luminosities, suggesting that they are genuine old ordinary pulsars unrelated to the superposed SNRs. This implies that CCOs are either latent radio pulsars that activate long after their SNRs dissipate or they remain permanently radio-quiet. The true descendants of CCOs remain at large.

  11. High performance bonded neo magnets using high density compaction

    NASA Astrophysics Data System (ADS)

    Herchenroeder, J.; Miller, D.; Sheth, N. K.; Foo, M. C.; Nagarathnam, K.

    2011-04-01

    This paper presents a manufacturing method called Combustion Driven Compaction (CDC) for the manufacture of isotropic bonded NdFeB magnets (bonded Neo). Magnets produced by the CDC method have density up to 6.5 g/cm3 which is 7-10% higher compared to commercially available bonded Neo magnets of the same shape. The performance of an actual seat motor with a representative CDC ring magnet is presented and compared with the seat motor performance with both commercial isotropic bonded Neo and anisotropic NdFeB rings of the same geometry. The comparisons are made at both room and elevated temperatures. The airgap flux for the magnet produced by the proposed method is 6% more compared to the commercial isotropic bonded Neo magnet. After exposure to high temperature due to the superior thermal aging stability of isotropic NdFeB powders the motor performance with this material is comparable to the motor performance with an anisotropic NdFeB magnet.

  12. Dynamic compact model of thermally assisted switching magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    El Baraji, M.; Javerliac, V.; Guo, W.; Prenat, G.; Dieny, B.

    2009-12-01

    The general purpose of spin electronics is to take advantage of the electron's spin in addition to its electrical charge to build innovative electronic devices. These devices combine magnetic materials which are used as spin polarizer or analyzer together with semiconductors or insulators, resulting in innovative hybrid CMOS/magnetic (Complementary MOS) architectures. In particular, magnetic tunnel junctions (MTJs) can be used for the design of magnetic random access memories [S. Tehrani, Proc. IEEE 91, 703 (2003)], magnetic field programmable gate arrays [Y. Guillement, International Journal of Reconfigurable Computing, 2008], low-power application specific integrated circuits [S. Matsunaga, Appl. Phys. Express 1, 091301 (2008)], and rf oscillators. The thermally assisted switching (TAS) technology requires heating the MTJ before writing it by means of an external field. It reduces the overall power consumption, solves the data writing selectivity issues, and improves the thermal stability of the written information for high density applications. The design of hybrid architectures requires a MTJ compact model, which can be used in standard electrical simulators of the industry. As a result, complete simulations of CMOS/MTJ hybrid circuits can be performed before experimental realization and testing. This article presents a highly accurate model of the MTJ based on the TAS technology. It is compatible with the Spectre electrical simulator of Cadence design suite.

  13. A compact permanent magnet cyclotrino for accelerator mass spectrometry

    SciTech Connect

    Young, A.T.; Clark, D.J.; Kunkel, W.B.; Leung, K.N.; Li, C.Y.

    1995-02-01

    The authors describe the development of a new instrument for the detection of trace amounts of rare isotopes, a Cyclotron Mass Spectrometer (CMS). A compact low energy cyclotron optimized for high mass resolution has been designed and has been fabricated. The instrument has high sensitivity and is designed to measure carbon-14 at abundances of < 10{sup {minus}12}. A novel feature of the instrument is the use of permanent magnets to energize the iron poles of the cyclotron. The instrument uses axial injection, employing a spiral inflector. The instrument has been assembled and preliminary measurements of the magnetic field show that it has a uniformity on the order of 2 parts in 10{sup 4}.

  14. GR-AMRVAC code applications: accretion onto compact objects, boson stars versus black holes

    NASA Astrophysics Data System (ADS)

    Meliani, Z.; Grandclément, P.; Casse, F.; Vincent, F. H.; Straub, O.; Dauvergne, F.

    2016-08-01

    In the close vicinity of a compact object strong gravity imprints its signature onto matter. Systems that contain at least one compact object are observed to exhibit extreme physical properties and typically emit highly energetic radiation. The nature of the compact objects that produce the strongest gravitational fields is to date not settled. General relativistic numerical simulations of fluid dynamics around black holes, neutron stars, and other compact objects such as boson stars (BSs) may give invaluable insights into this fundamental question. In order to study the behavior of fluid in the strong gravity regime of an arbitrary compact object we develop a new general relativistic hydrodynamics code. To this end we extend the existing versatile adaptive mesh refinement code MPI-AMRVAC into a general relativistic hydrodynamics framework and adapt it for the use of numerically given spacetime metrics. In the present article we study accretion flows in the vicinity of various types of BSs whose numerical metrics are calculated by the KADATH spectral solver library. We design specific tests to check the reliability of any code intending to study BSs and compare the solutions with those obtained in the context of Schwarzschild black holes. We perform the first ever general relativistic hydrodynamical simulations of gas accretion by a BS. The behavior of matter at small distances from the center of a BS differs notably from the black hole case. In particular we demonstrate that in the context of Bondi spherical accretion the mass accretion rate onto non-rotating BSs remains constant whereas it increases for Schwarzschild black holes. We also address the scenario of non-spherical accretion onto BSs and show that this may trigger mass ejection from the interior of the BS. This striking feature opens the door to forthcoming investigations regarding accretion-ejection flows around such types of compact objects.

  15. HARD X-RAY FLUX UPPER LIMITS OF CENTRAL COMPACT OBJECTS IN SUPERNOVA REMNANTS

    SciTech Connect

    Erdeve, I.; Kalemci, E.; Alpar, M. A.

    2009-05-10

    We searched for hard X-ray (20-300 keV) emission from nine central compact objects (CCOs) 1E 1207.4-5209, 1WGA J1713-3949, J082157.5-430017, J085201.4-461753, J160103.1-513353, J1613483-5055, J181852.0-150213, J185238.6+004020, and J232327.9+584843 with the International Gamma-Ray Astrophysics Laboratory observatory. We applied spectral imaging analysis and did not detect any of the sources with luminosity upper limits in the range of 10{sup 33}-10{sup 34} erg s{sup -1} in the 20-75 keV band. For nearby CCOs (less than 4 kpc), the upper-limit luminosities are an order of magnitude lower than the measured persistent hard X-ray luminosities of anomalous X-ray pulsars. This may indicate that the CCOs are low magnetic field systems with fallback disks around them.

  16. Maria Goeppert-Mayer Award Talk: Formation and Evolution of Compact Objects in Binary Systems

    NASA Astrophysics Data System (ADS)

    Kalogera, Vicky

    2008-04-01

    Ever since their discovery, first as X-ray sources and later as radio pulsars, binary stellar systems harboring neutron stars or black holes have been pivotal in our efforts to understand the formation and evolution of these most compact objects and the implications for gravitational wave searches. I will review some recent surprising results linking the formation of neutron stars and black holes. I will also discuss how studies of double compact objects can help uncover the origin of short gamma-ray bursts and assess the prospects for gravitational wave detections in the near future.

  17. Characteristics of the magnetic field distribution on compact NMR magnets using cryocooled HTS bulks

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Takano, R.; Nakano, T.; Imai, M.; Hahn, S. Y.

    2009-10-01

    Recently, the performance of high temperature superconducting (HTS) bulks such as critical current density, size, and mechanical strength has been improved rapidly. So, various applications using HTS bulks such as motors, bearings and flywheels have been investigated by many research groups. A compact nuclear magnetic resonance (NMR) magnet is one of the new applications after a technique to enhance maximum trapped field of the HTS bulk more than 11.7 T (500 MHz 1H NMR frequency) has been developed. This new compact NMR magnet out of HTS bulks is cost-effective compared with conventional NMR magnets and then expected to be widely used in food and drug industry. In design and manufacture of the compact NMR magnets, spatial field homogeneity of the large trapped magnetic field in HTS bulk annuli is a crucial issue because the behavior of a trapped field is highly non-linear and, as a result, a technique to improve the field homogeneity such as active/passive shimming now becomes more challenging compared with that of the conventional counterparts. This paper presents the magnetic field distributions in single and three assembled HTS bulk annuli measured by a 3-axis and multi-arrayed Hall sensor under two different cryogenic environments: (1) in a bath of liquid nitrogen (LN 2) and (2) dry cooling by a cryocooler. The spatial homogeneity changes with various operating temperatures were investigated and the effect of critical current density enhancement by lowering the operating temperature on the field homogeneity improvement was discussed in detail.

  18. KINETIC THEORY OF EQUILIBRIUM AXISYMMETRIC COLLISIONLESS PLASMAS IN OFF-EQUATORIAL TORI AROUND COMPACT OBJECTS

    SciTech Connect

    Cremaschini, Claudio; Kovář, Jiří; Slaný, Petr; Stuchlík, Zdeněk; Karas, Vladimír

    2013-11-01

    The possible occurrence of equilibrium off-equatorial tori in the gravitational and electromagnetic fields of astrophysical compact objects has been recently proved based on non-ideal magnetohydrodynamic theory. These stationary structures can represent plausible candidates for the modeling of coronal plasmas expected to arise in association with accretion disks. However, accretion disk coronae are formed by a highly diluted environment, and so the fluid description may be inappropriate. The question is posed of whether similar off-equatorial solutions can also be determined in the case of collisionless plasmas for which treatment based on kinetic theory, rather than a fluid one, is demanded. In this paper the issue is addressed in the framework of the Vlasov-Maxwell description for non-relativistic, multi-species axisymmetric plasmas subject to an external dominant spherical gravitational and dipolar magnetic field. Equilibrium configurations are investigated and explicit solutions for the species kinetic distribution function are constructed, which are expressed in terms of generalized Maxwellian functions characterized by isotropic temperature and non-uniform fluid fields. The conditions for the existence of off-equatorial tori are investigated. It is proved that these levitating systems are admitted under general conditions when both gravitational and magnetic fields contribute to shaping the spatial profiles of equilibrium plasma fluid fields. Then, specifically, kinetic effects carried by the equilibrium solution are explicitly provided and identified here with diamagnetic energy-correction and electrostatic contributions. It is shown that these kinetic terms characterize the plasma equation of state by introducing non-vanishing deviations from the assumption of thermal pressure.

  19. Compact ECR ion source with permanent magnets for carbon therapy

    NASA Astrophysics Data System (ADS)

    Muramatsu, M.; Kitagawa, A.; Sakamoto, Y.; Sato, Y.; Yamada, S.; Ogawa, H.; Drentje, A. G.; Biri, S.; Yoshida, Y.

    2004-05-01

    Ion sources for the medical facilities should have the following characteristics of easy maintenance, low electric power, good stability, and long operation time without trouble (1 year or longer). For this, a 10 GHz compact electron cyclotron resonance ion source (ECRIS) with all permanent magnets was developed. The beam intensity and stability for C4+ were 280 e μA and better than 6% during 20 h with no adjustment of any source parameters. These results were acceptable for the medical requirements. Recently, many plans were proposed to construct the next generation cancer treatment facility. For such a facility we have designed an all permanent magnet ECRIS, in which a high magnetic field is chosen for increasing the beam intensity. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas injection side, while the minimum B strength is 0.25 T. The source has a diameter of 32 cm and a length of 29.5 cm. Details of the design of this source and its background are described in this article.

  20. Radial oscillation of compact stars in the presence of magnetic field

    NASA Astrophysics Data System (ADS)

    Baral, R. C.; Mohanta, K. K.; Panda, N. R.; Sahu, P. K.

    2016-06-01

    Compact stars are classified into three categories: neutron stars (NSs), quark stars (QSs) and hybrid stars (HSs). Stars having only hadronic matter are NSs, QSs having only quark matter up to u, d and s quarks and stars having quark core surrounded by a mixed matter (hadronic matter and quark matter) followed by hadronic matter are HSs. The mixed matter is well distributed to both hadron and quark matters. A huge magnetic field is predicted in the core of the neutron star and is observed in the surface of the neutron star. We study the effect of such huge magnetic field in the matter inside the compact objects basically the equation of state (EOS) of the matters. Since matter inside the star are very dense both hadronic and quark matter, we consider relativistic mean field theory in the hadronic matter and simple MIT bag model in the quark matter in the presence of strong magnetic field. We calculate the phase transition between hadronic and quark phases, maximum mass and eigenfrequencies of radial pulsation of NS, HS and QS in the presence of such a huge magnetic field. The mixed phase is constructed by using Glendenning conjecture in between hadron and quark phases. We find in the presence of magnetic field, the EOS in both matter becomes soft. As a result, the maximum mass is reduced and the period of oscillation is changed significantly and there is a sudden dip in the period of oscillations in the HS, which signifies the transition from one to another matter.

  1. Bidirectional motion observed in the compact symmetric object 1946+708.

    PubMed Central

    Taylor, G B; Vermeulen, R C; Pearson, T J

    1995-01-01

    We present the first direct measurements of bidirectional motions in an extragalactic radio jet. The radio source 1946+708 is a compact symmetric object with striking S-symmetry identified with a galaxy at a redshift of 0.101. From observations 2 years apart we have determined the velocities of four compact components in the jet, the fastest of which has an apparent velocity of 1.09 h-1c. By pairing up the components, assuming they were simultaneously ejected in opposite directions, we derive a 1 lower limit on the Hubble constant, H0 > 42 km.s-1.Mpc-1. PMID:11607603

  2. WHAT IS ON TAP? THE ROLE OF SPIN IN COMPACT OBJECTS AND RELATIVISTIC JETS

    SciTech Connect

    King, Ashley L.; Miller, Jon M.; Gueltekin, Kayhan; Walton, Dominic J.; Fabian, Andrew C.; Reynolds, Christopher S.; Nandra, Kirpaul

    2013-07-10

    We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3{sigma} confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3{sigma} confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4{sigma} and 4.1{sigma} confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log ({nu}L{sub R}/L{sub Bol}{sup 0.67}/M{sub BH}{sup 0.78})) and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e., bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the

  3. Magnetic Bubble Expansion Experimental Investigation Using a Compact Coaxial Magnetized Plasma Gun

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Hsu, Scott; Li, Hui; Liu, Wei; Gilmore, Mark; Watts, Christopher

    2009-11-01

    The poster will first discuss the construction and improved design of a compact coaxial magnetized plasma gun. The plasma gun is used for experimental studies of magnetic bubble expansion into a lower pressure background plasma, which as a model for extragalactic radio lobes and solar coronal mass ejections. In this experiment, the plasma bubble's density, electron temperature, and propagation speed are measured by using a multiple-tipped langmuir probe. Also a three axis B-dot probe array is used to measure the magnetic field in three dimensions during the expansion process. In this poster experiment setup and data will be provided. Finally the comparison with the simulation result will be made.

  4. Magnetar-like Activity from the Central Compact Object in the SNR RCW103

    NASA Astrophysics Data System (ADS)

    Rea, N.; Borghese, A.; Esposito, P.; Coti Zelati, F.; Bachetti, M.; Israel, G. L.; De Luca, A.

    2016-09-01

    The 6.67 hr periodicity and the variable X-ray flux of the central compact object (CCO) at the center of the supernova remnant RCW 103, named 1E 161348–5055, have been always difficult to interpret within the standard scenarios of an isolated neutron star (NS) or a binary system. On 2016 June 22, the Burst Alert Telescope (BAT) on board Swift detected a magnetar-like short X-ray burst from the direction of 1E 161348–5055, also coincident with a large long-term X-ray outburst. Here, we report on Chandra, Nuclear Spectroscopic Telescope Array, and Swift (BAT and XRT) observations of this peculiar source during its 2016 outburst peak. In particular, we study the properties of this magnetar-like burst, we discover a hard X-ray tail in the CCO spectrum during outburst, and we study its long-term outburst history (from 1999 to 2016 July). We find the emission properties of 1E 161348–5055 consistent with it being a magnetar. However, in this scenario, the 6.67 hr periodicity can only be interpreted as the rotation period of this strongly magnetized NS, which therefore represents the slowest pulsar ever detected, by orders of magnitude. We briefly discuss the viable slow-down scenarios, favoring a picture involving a period of fall-back accretion after the supernova explosion, similarly to what is invoked (although in a different regime) to explain the “anti-magnetar” scenario for other CCOs.

  5. Development of a compact superconducting magnet with a GdBCO magnetic lens

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Y.; Matsumoto, S.; Teranishi, R.; Kiyoshi, T.

    2013-10-01

    Concentration of a magnetic field has been achieved using a Gd-Ba-Cu-O (GdBCO) magnetic lens. A conduction-cooled compact high-field superconducting magnet with a GdBCO magnetic lens was developed. The magnet possessed a 10-mm room-temperature bore and consisted of two Nb-Ti solenoid coils and a GdBCO magnetic lens, which was installed at the center of the Nb-Ti coils in order to concentrate the background field generated by the Nb-Ti coils. The Nb-Ti coils and the GdBCO magnetic lens were cooled using a two-stage pulse-tube cryocooler. A concentrated magnetic field of 10.3 T was obtained at a background field of 5.6 T provided by the Nb-Ti coils. No degradation was found in the magnet during repeat excitation. The large field gradient generated by the GdBCO magnetic lens is expected to be used for the levitation of diamagnetic materials.

  6. A search for pulsations from the compact object of GRB 060218

    NASA Astrophysics Data System (ADS)

    Mirabal, N.; Gotthelf, E. V.

    2010-02-01

    Aims: A fraction of massive stars are expected to collapse into compact objects (accreting black holes or rapidly rotating neutron stars) that successfully produce gamma-ray bursts (GRBs). We examine the possibility of directly observing these gamma-ray burst compact objects (GCOs) using post-explosion observations of past and future GRB sites. Methods: We present a search for early pulsations from the nearby (z=0.0335) gamma-ray burst GRB 060218, which exhibited features possibly consistent with a rapidly spinning neutron star as its underlying GCO. We also consider alternative techniques that could potentially achieve a detection of GCOs either in the Local Volume or near the plane of our own Galaxy. Results: We report the non-detection of pulsations from the GCO of GRB 060218. In particular, fast fourier transform analysis applied to the light curve shows no significant power over the range of frequencies 0.78 mHz < f < 227 Hz with an upper limit on the pulsed fraction of ~2%. In addition, we present detection limits of current high-resolution archival X-ray images of galaxies within the Local Volume. The existing data could be harnessed to rule out the presence of any background contaminants at the GRB position of future nearby events. Conclusions: The null detection of pulsations from the GCO of GRB 060218 is most likely explained by the fact that the afterglow emission occurs near the head of the jet and should be far removed from the compact object. We also find that the comparison of pre- and post-explosion explosion images of future GRBs within the Local Volume, as well as the firm identification of a GCO within an ancient GRB remnant near the Galactic plane are extremely challenging with current GeV/TeV capabilities. Finally, we conclude that only under some very exceptional circumstances will it be possible to directly detect the compact object responsible for gamma-ray bursts.

  7. Exploring the Physics of Compact Objects with Gravitational-Wave Astronomy

    NASA Astrophysics Data System (ADS)

    Brown, Duncan

    2016-03-01

    The Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) has recently completed its first observing run. Future observations of gravitational waves by LIGO will open a new field in astronomy. The gravitational waves radiated by binaries containing neutron stars and/or black holes contain information about strong field gravity and the properties of dense matter. In this talk I will discuss the nuclear and gravitational physics that can be learned from the observation of compact-object mergers

  8. Spectral calculation through outflows around compact objects and its hydrodynamic simulation

    NASA Astrophysics Data System (ADS)

    Yoshida, Tessei; Ebisawa, Ken; Tsujimoto, Masahiro; Ohsuga, Ken; Nakagawa, Yujin; Nomura, Mariko

    Compact objects such as black holes and neutron starts are shining by converting the gravitational energy via mass accretion. Recent theoretical studies predict that outflows tend to accompany the mass accretion process and affect X-ray spectra. In fact, ``blue-shifted'' metal absorption lines have been observed from active galactic nuclei and X-ray binaries, indicating that the absorbers are moving toward us, namely the outflows do exist. In order to constrain physical conditions and geometries around the compact objects, we need to compare the observed X-ray spectra and theoretically expected signatures caused by the outflows. For the observational side, we will use the micro calorimeter with the unprecedented spectral resolution of E/DeltaE˜1000 on-board Astro-H (in 2015 launch), which is the ONLY detector that can observe the detailed line profiles containing information of the outflows. The radiation-hydrodynamic simulation is needed to interpret the Astro-H spectra. We construct the spectral model by the following two theoretical steps: We first determine the density and velocity profiles of the outflows around the compact object by a hydrodynamic simulation. We then calculate X-ray spectra through such outflows, by using the spectral synthesis code ``Cloudy''. We present the results of the simulated profiles and the calculated spectra.

  9. SUBARU AND GEMINI OBSERVATIONS OF SS 433: NEW CONSTRAINT ON THE MASS OF THE COMPACT OBJECT

    SciTech Connect

    Kubota, K.; Ueda, Y.; Fabrika, S.; Barsukova, E. A.; Sholukhova, O.; Medvedev, A.; Goranskij, V. P.

    2010-02-01

    We present results of optical spectroscopic observations of the mass donor star in SS 433 with Subaru and Gemini, with an aim to best constrain the mass of the compact object. Subaru/Faint Object Camera and Spectrograph observations were performed on four nights of 2007 October 6-8 and 10, covering the orbital phase of phi = 0.96 - 0.26. We first calculate the cross-correlation function (CCF) of these spectra with that of the reference star HD 9233 in the wavelength range of 4740-4840 A. This region is selected to avoid 'strong' absorption lines accompanied with contaminating emission components, which most probably originate from the surroundings of the donor star, such as the wind and gas stream. The same analysis is applied to archive data of Gemini/GMOS taken at phi = 0.84 - 0.30 by Hillwig and Gies. From the Subaru and Gemini CCF results, the amplitude of the radial velocity curve of the donor star is determined to be 58.3 +- 3.8 km s{sup -1} with a systemic velocity of 59.2 +- 2.5 km s{sup -1}. Together with the radial velocity curve of the compact object, we derive the mass of the donor star and compact object to be M{sub O} = 12.4 +- 1.9 M{sub sun} and M{sub X} = 4.3 +- 0.6 M{sub sun}, respectively. We conclude, however, that these values should be taken as upper limits. From the analysis of the averaged absorption line profiles of strong lines (mostly ions) and weak lines (mostly neutrals) observed with Subaru, we find evidence for heating effects from the compact object. Using a simple model, we find that the true radial velocity amplitude of the donor star could be as low as 40 +- 5 km s{sup -1} in order to produce the observed absorption-line profiles. Taking into account the heating of the donor star may lower the derived masses to M{sub O} = 10.4{sup +2.3}{sub -1.9} M{sub sun} and M{sub X} = 2.5{sup +0.7}{sub -0.6} M{sub sun}. Our final constraint, 1.9 M{sub sun} <=M{sub X}<= 4.9 M{sub sun}, indicates that the compact object in SS 433 is most likely a

  10. Anti-magnetars: Revealing the Pulsar Properties of Central Compact Objects in Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Gotthelf, Eric

    This proposal is to fund the analysis of large data sets that we were awarded in XMM- Newton AO9 to search for the pulsation periods and measure the spin-down rates of Central Compact Objects (CCOs) in supernova remnants (SNRs). These observations include a Large Program (350 ks) to search for the pulsar in Cas A, and a multi-epoch timing program (200 ks total) to measure the spin-down rate and dipole magnetic field strength of the newly discovered 0.112 s PSR J0821-4300 in Puppis A. These observations are motivated by growing evidence that the class of CCOs, which are detected only in X-rays and are the least conspicuous of young neutron stars, are characterized by weak dipole magnetic fields and relatively long initial spin periods. As such, they may comprise a large fraction of neutron star births. From upper limits that we established on their spin-down rates, as well as one measurement of P-dot in a CCO, we developed the "anti-magnetar" model, which describes CCOs as pulsars with even weaker magnetic fields (B_s = 1.e10-1.e11 G) than ordinary young pulsars. The approved observations will provide strong confirmation of this model if the expected slow spin-down rate of PSR J0821-4300 is measured, and if similar spin properties are discovered from the Cas A CCO. The remaining mystery of CCOs is what maintains their small, hot regions of surface thermal X-ray emission. Spin-down power is insufficient; otherwise, only the effects of strong (B_s > 1.e13 G) magnetic fields are thought able to enforce nonuniform surface temperature, in apparent contradiction to the anti-magnetar hypothesis. We will apply a detailed ray-tracing code to model the energy-dependent light curves and phase-resolved spectra of PSR J0821-430 and other CCOs in order to determine the geometry of their surface hot spots with respect to the rotation axis and viewing direction. Evidence for cyclotron resonance lines in the spectra will also be modeled as a function of rotation phase, which will

  11. Compact magnetic antennas for directional excitation of surface plasmons.

    PubMed

    Liu, Yongmin; Palomba, Stefano; Park, Yongshik; Zentgraf, Thomas; Yin, Xiaobo; Zhang, Xiang

    2012-09-12

    Plasmonics is considered as one of the most promising candidates for implementing the next generation of ultrafast and ultracompact photonic circuits. Considerable effort has been made to scale down individual plasmonic components into the nanometer regime. However, a compact plasmonic source that can efficiently generate surface plasmon polaritons (SPPs) and deliver SPPs to the region of interest is yet to be realized. Here, bridging the optical antenna theory and the recently developed concept of metamaterials, we demonstrate a subwavelength, highly efficient plasmonic source for directional generation of SPPs. The designed device consists of two nanomagnetic resonators with detuned resonant frequencies. At the operating wavelength, incident photons can be efficiently channeled into SPP waves modulated by the electric field polarization. By tailoring the relative phase at resonance and the separation between the two nanoresonators, SPPs can be steered to predominantly propagate along one specific direction. This novel magnetic nanoantenna paves a new way to manipulate photons in the near-field, and also could be useful for SPP-based nonlinear applications, active modulations, and wireless optical communications. PMID:22845720

  12. Numerical simulations of axisymmetric Bondi-Hoyle accretion onto a compact object

    NASA Astrophysics Data System (ADS)

    El Mellah, I.; Casse, F.

    2015-12-01

    Compact bodies which are not at rest compare to an homogeneous ambient environment are believed to undergo Bondi-Hoyle axisymmetric accretion as soon as their relative velocity reaches supersonic levels. Contrary to its spherical counterpart, B-H accretion presents flow structures difficult to analytically derive, hence the need for numerical investigations. The broad dynamics at stake when a tiny compact object engulfs surrounding material at a much larger scale has made numerical consistency a polemical issue as it has prevented both scales to be grasped for reasonable wind velocities. We designed a numerical setup which reconciliates the requirement for finite size accretor with steady states properties of the Bondi-Hoyle flow independent of the size of the inner boundary. The robustness of this setup is evaluated accordingly to predictions concerning the mass accretion rate evolution with the Mach number at infinity and the topology of the sonic surface as determined by te{Foglizzo1996}. It provides an estimation of the mass accretion rates and thus, of the expected X-ray luminosity for an idealized B-H configuration which might not be too far off for isolated compact objects like runaway neutron stars or hyper-luminous X-ray sources.

  13. Upper bound on the magnetic field strength in the quark core of a strongly-magnetized compact star

    NASA Astrophysics Data System (ADS)

    Isayev, Alexander; Yang, Jongmann

    2014-09-01

    Two types of strongly-magnetized compact stars, represented by magnetized strange quark stars and magnetized hybrid stars, are considered. In each case, there exists an upper bound H max on the magnetic field strength in the interior of a compact star. For a magnetized strange quark star, H max is determined by the magnetic field at which the upper bound on the bag pressure from the absolute stability window of magnetized strange quark matter (SQM) vanishes, assuming the Massachusetts Institute of Technology bag model description of SQM. For a hybrid star, H max is represented by the critical magnetic field for the occurrence of a longitudinal (along the magnetic field) instability in the quark core, at which the longitudinal pressure in magnetized SQM vanishes.

  14. Design of permanent magnets to chaoize doubly salient permanent magnet motors for electric compaction

    NASA Astrophysics Data System (ADS)

    Chau, K. T.; Wang, Zheng

    2006-04-01

    This article proposes and implements a class of chaotic motors for electric compaction. The key is to develop a design approach for the permanent magnets (PMs) of doubly salient PM (DSPM) motors in such a way that chaotic motion can be naturally produced. The bifurcation diagram is employed to derive the threshold of chaoization in terms of PM flux, while the corresponding phase-plane trajectories are used to characterize the chaotic motion. A practical three-phase 12/8-pole DSPM motor is used for exemplification. The proposed chaotic motor is critically assessed for application to a vibratory soil compactor, which is proven to offer better compaction performance than its counterparts. Both computer simulation and experimental results are given to illustrate the proposed chaotic motor.

  15. Compact dark matter objects, asteroseismology, and gravitational waves radiated by sun

    SciTech Connect

    Pokrovsky, Yu. E.

    2015-12-15

    The solar surface oscillations observed by Crimean Astrophysical Observatory and Solar Helioseismic Observatory are considered to be excited by a small fraction of Dark Matter in form of Compact Dark Matter Objects (CDMO) in the solar structure. Gravitational Waves (GW) radiated by these CDMO are predicted to be the strongest at the Earth and are easily detectable by European Laser Interferometer Space Antenna or by Gravitational-Wave Observatory “Dulkyn” which can solve two the most challenging tasks in the modern physics: direct detection of GW and DM.

  16. First spectroscopy of a short-hard GRB: the environment of a compact object merger

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, Antonio; Thöne, Christina C.; Rowllinson, Antonia; Benito, Rubén García; Levan, Andrew J.; Gorosabel, Javier; Goldoni, Paolo; Schulze, Steve

    2015-03-01

    Short gamma-ray bursts (GRBs) are an extremely elusive family of cosmic explosions. They are thought to be related to the violent merger of compact objects (such as a neutron stars or black holes). Their optical counterparts were not discovered until 2005, and since then, there had been no successful spectroscopic observations. Here we present the first spectra of a short GRB, which we use to study the environment and derive implications on the progenitors of these cosmic explosions. This poster is based on the work by de Ugarte Postigo et al. (2014).

  17. Subaru And Gemini Observations Of SS 433: New Constraint On The Mass Of The Compact Object

    NASA Astrophysics Data System (ADS)

    Kubota, K.; Ueda, Y.; Fabrika, S.; Medvedev, A.; Barsukova, E. A.; Sholukhova, O.; Goranskij, V. P.

    2010-02-01

    We present results of optical spectroscopic observations of the mass donor star in SS 433 with Subaru and Gemini, with an aim to best constrain the mass of the compact object. Subaru/Faint Object Camera and Spectrograph observations were performed on four nights of 2007 October 6-8 and 10, covering the orbital phase of phi = 0.96 - 0.26. We first calculate the cross-correlation function (CCF) of these spectra with that of the reference star HD 9233 in the wavelength range of 4740-4840 Å. This region is selected to avoid "strong" absorption lines accompanied with contaminating emission components, which most probably originate from the surroundings of the donor star, such as the wind and gas stream. The same analysis is applied to archive data of Gemini/GMOS taken at phi = 0.84 - 0.30 by Hillwig & Gies. From the Subaru and Gemini CCF results, the amplitude of the radial velocity curve of the donor star is determined to be 58.3 ± 3.8 km s-1 with a systemic velocity of 59.2 ± 2.5 km s-1. Together with the radial velocity curve of the compact object, we derive the mass of the donor star and compact object to be M O = 12.4 ± 1.9 M sun and M X = 4.3 ± 0.6 M sun, respectively. We conclude, however, that these values should be taken as upper limits. From the analysis of the averaged absorption line profiles of strong lines (mostly ions) and weak lines (mostly neutrals) observed with Subaru, we find evidence for heating effects from the compact object. Using a simple model, we find that the true radial velocity amplitude of the donor star could be as low as 40 ± 5 km s-1 in order to produce the observed absorption-line profiles. Taking into account the heating of the donor star may lower the derived masses to M O = 10.4+2.3 -1.9 M sun and M X = 2.5+0.7 -0.6 M sun. Our final constraint, 1.9 M sun <=M X<= 4.9 M sun, indicates that the compact object in SS 433 is most likely a low mass black hole, although the possibility of a massive neutron star cannot be firmly

  18. Time evolution of accreting magnetofluid around a compact object-Newtonian analysis

    NASA Astrophysics Data System (ADS)

    Habibi, Fahimeh; Shaghaghian, Mahboobeh; Pazhouhesh, Reza

    2015-07-01

    Time evolution of a thick disc with finite conductivity around a nonrotating compact object is presented. Along with the Maxwell equations and the Ohm's law, the Newtonian limit of the relativistic fluid equations governing the motion of a finitely conducting plasma is derived. The magnetofluid is considered to possess only the poloidal components of the electromagnetic field. Moreover, the shear viscous stress is neglected, as well as the self-gravity of the disc. In order to solve the equations, we have used a self-similar solution. The main features of this solution are as follows. The azimuthal velocity is somewhat increased from the Keplerian value in the equator plane to the super-Keplerian values at the surface of disc. Moreover, the radial velocity is obtained proportional to the meridional velocity. Magnetofluid does not have any nonzero component of the current density. Subsequently, the electromagnetic force is vanished and does not play any role in the force balance. While the pressure gradient maintains the disc structure in latitudinal direction, magnetofluid has no accretion on the central compact object. Analogously to the parameter α in the standard model, our calculations contain one parameter η0 which specifies the size of the electrical resistivity.

  19. Gravitational-wave radiation from double compact objects with eLISA in the Galaxy

    NASA Astrophysics Data System (ADS)

    Liu, Jinzhong; Zhang, Yu

    2014-03-01

    The phase of inspiral of double compact objects (DCOs: NS + WD, NS + NS, BH + NS, and BH + BH binaries) in the disk field population of the Galaxy provides a potential source in the frequency range from 10-4 to 0.1 Hz, which can be detected by the European New Gravitational Observatory (NGO: eLISA is derived from the previous LISA proposal) project. In this frequency range, much stronger gravitational wave (GW) radiation can be obtained from DCO sources because they possess more mass than other compact binaries (e.g., close double white dwarfs). In this study, we aim to calculate the gravitational wave signals from the resolvable DCO sources in the Galaxy using a binary population synthesis approach, and determine physical properties of these binaries using Monte Carlo simulations. Combining the sensitivity curve of the eLISA detector and a confusion-limited noise floor of close double white dwarfs, we find that only a handful of DCO sources can be detected by the eLISA detector. The detectable number of DCO sources reaches 160; in the context of low-frequency eLISA observations we find that the number of NS + WD, NS + NS, BH + NS, and BH + BH objects are 132, 16, 3, and 6, respectively.

  20. Insights into stellar and binary evolution from gravitational-wave observations of merging compact objects

    NASA Astrophysics Data System (ADS)

    Stevenson, Simon

    2016-07-01

    Advanced LIGO finished its first observing run (O1) at the begining of 2016, at a sensitivity ~3 times that of the initial LIGO detectors. This increased sensitivity makes the possibility of detecting gravitational-waves a realistic prospect over the next few years. One of the most promising sources for advanced gravitational-wave detectors is the merger of two compact objects; neutron stars or black holes. These objects are formed as the end point of the evolution of massive stars in close binaries. There remain many poorly understood processes in the lives of massive stars and the evolution of close binary systems. These processes include the distribution of kicks received by black holes at birth, the amount of angular momentum lost from a system during a mass transfer episode, and the common envelope event. One way of attempting to understand these processes is to attempt to constrain them observationally using eventual gravitational-wave observations of compact binary mergers. Here we present recent work on this front.

  1. Accretion-caused deceleration of a gravitationally powerful compact stellar object moving within a dense Fermi gas

    NASA Astrophysics Data System (ADS)

    Tito, E. P.; Pavlov, V. I.

    2016-07-01

    We consider accretion-caused deceleration of a gravitationally-powerful compact stellar object traveling within a cold Fermi-gas medium. We provide analytical and numerical estimates of the effect manifestation.

  2. Universal charge-radius relation for subatomic and astrophysical compact objects.

    PubMed

    Madsen, Jes

    2008-04-18

    Electron-positron pair creation in supercritical electric fields limits the net charge of any static, spherical object, such as superheavy nuclei, strangelets, and Q balls, or compact stars like neutron stars, quark stars, and black holes. For radii between 4 x 10(2) and 10(4) fm the upper bound on the net charge is given by the universal relation Z=0.71R(fm), and for larger radii (measured in femtometers or kilometers) Z=7 x 10(-5)R_(2)(fm)=7 x 10(31)R_(2)(km). For objects with nuclear density the relation corresponds to Z approximately 0.7A(1/3)( (10(8)10(12)), where A is the baryon number. For some systems this universal upper bound improves existing charge limits in the literature. PMID:18518093

  3. MICROLENSING-BASED ESTIMATE OF THE MASS FRACTION IN COMPACT OBJECTS IN LENS GALAXIES

    SciTech Connect

    Mediavilla, E.; Guerras, E.; Canovas, H.; Oscoz, A.; Falco, E.; Motta, V.; Jean, C.; Mosquera, A. M.

    2009-12-01

    We estimate the fraction of mass that is composed of compact objects in gravitational lens galaxies. This study is based on microlensing measurements (obtained from the literature) of a sample of 29 quasar image pairs seen through 20 lens galaxies. We determine the baseline for no microlensing magnification between two images from the ratios of emission line fluxes. Relative to this baseline, the ratio between the continua of the two images gives the difference in microlensing magnification. The histogram of observed microlensing events peaks close to no magnification and is concentrated below 0.6 mag, although two events of high magnification, DELTAm approx 1.5, are also present. We study the likelihood of the microlensing measurements using frequency distributions obtained from simulated microlensing magnification maps for different values of the fraction of mass in compact objects, alpha. The concentration of microlensing measurements close to DELTAm approx 0 can be explained only by simulations corresponding to very low values of alpha (10% or less). A maximum likelihood test yields alpha = 0.05{sup +0.09}{sub -0.03} (90% confidence interval) for a quasar continuum source of intrinsic size r{sub s{sub 0}}approx2.6x10{sup 15} cm. This estimate is valid in the 0.1-10 M {sub sun} range of microlens masses. We study the dependence of the estimate of alpha with r{sub s{sub 0}}, and find that alpha approx< 0.1 for r{sub s{sub 0}}approx<1.3x10{sup 16} cm. High values of alpha are possible only for source sizes much larger than commonly expected (r{sub s{sub 0}}>>2.6x10{sup 16} cm). Regarding the current controversy about Milky Way/LMC and M31 microlensing studies, our work supports the hypothesis of a very low content in MACHOS (Massive Compact Halo Objects). In fact, according to our study, quasar microlensing probably arises from the normal star populations of lens galaxies and there is no statistical evidence for MACHOS in the dark halos.

  4. Numerical simulations of axisymmetric hydrodynamical Bondi-Hoyle accretion on to a compact object

    NASA Astrophysics Data System (ADS)

    El Mellah, I.; Casse, F.

    2015-12-01

    Bondi-Hoyle accretion configurations occur as soon as a gravitating body is immersed in an ambient medium with a supersonic relative velocity. From wind-accreting X-ray binaries to runaway neutron stars, such a regime has been witnessed many times and is believed to account for shock formation, the properties of which can be only marginally derived analytically. In this paper, we present the first results of the numerical characterization of the stationary flow structure of Bondi-Hoyle accretion on to a compact object, from the large-scale accretion radius down to the vicinity of the compact body. For different Mach numbers, we study the associated bow shock. It turns out that those simulations confirm the analytical prediction by Foglizzo & Ruffert concerning the topology of the inner sonic surface with an adiabatic index of 5/3. They also enable us to derive the related mass accretion rates, the position and the temperature of the bow shock, as function of the flow parameters, along with the transverse density and temperature profiles in the wake.

  5. Estimating locations and total magnetization vectors of compact magnetic sources from scalar, vector, or tensor magnetic measurements through combined Helbig and Euler analysis

    USGS Publications Warehouse

    Phillips, J.D.; Nabighian, M.N.; Smith, D.V.; Li, Y.

    2007-01-01

    The Helbig method for estimating total magnetization directions of compact sources from magnetic vector components is extended so that tensor magnetic gradient components can be used instead. Depths of the compact sources can be estimated using the Euler equation, and their dipole moment magnitudes can be estimated using a least squares fit to the vector component or tensor gradient component data. ?? 2007 Society of Exploration Geophysicists.

  6. Nuclear gamma rays from compact objects. [nuclear interactions around neutron stars and black holes

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Higdon, J. C.; Ramaty, R.

    1978-01-01

    Accreting compact objects may be important gamma ray line sources and may explain recent observations of celestial gamma-ray line emission from a transient source in the direction of the galactic anti-center, from the galactic center, and possibly from the radio galaxy Centaurus A. The identification of the lines from the transient source requires a strong redshift. Such a redshift permits the identification of these lines with the most intense nuclear emission lines expected in nature, positron annihilation, and neutron capture on hydrogen and iron. Their production as a result of nuclear interactions in accreting gas around a neutron star is proposed. The gamma-ray line emission from the galactic center and possibly Centaurus A appears to have a surprisingly high luminosity, amounting to perhaps as much as 10% of the total luminosity of these sources. Such high gamma-ray line emission efficiencies could result from nuclear interactions in accreting gas around a massive black hole.

  7. Compact symmetric objects and supermassive binary black holes in the VLBA Imaging and Polarimetry Survey

    NASA Astrophysics Data System (ADS)

    Tremblay, S. E.; Taylor, G. B.; Ortiz, A. A.; Tremblay, C. D.; Helmboldt, J. F.; Romani, R. W.

    2016-06-01

    We present multifrequency Very Long Baseline Array (VLBA) follow-up observations of VLBA Imaging and Polarimetry Survey sources identified as likely compact symmetric objects (CSOs) or supermassive binary black holes (SBBHs). We also present new spectroscopic redshifts for 11 sources observed with the Hobby-Eberly Telescope. While no new SBBHs can be confirmed from these observations, we have identified 24 CSOs in the sample, 15 of which are newly designated, and refuted 52 candidates leaving 33 unconfirmed candidates. This is the first large uniform sample of CSOs which can be used to elicit some of the general properties of these sources, including morphological evolution and environmental interaction. We have detected polarized emission from two of these CSOs the properties of which are consistent with active galactic nuclei unification schemes.

  8. Exploring the Environs of Compact Symmetric Objects in the Nuclei of Galaxies and Quasars

    NASA Astrophysics Data System (ADS)

    Taylor, G. B.; Xu, W.; Readhead, A. C. S.; Pearson, T. J.

    1994-12-01

    Two large Caltech--Jodrell Bank VLBI surveys at 5 GHz have recently been completed (CJ1 -- Xu et al. 1994, ApJS, submitted; CJ2 -- Taylor et al. 1994, ApJS, in press; Henstock et al. 1994, ApJS, submitted). Together with the Pearson--Readhead survey (1988, ApJ, 328, 114) these provide ~ 1 mas resolution images for a flux limited sample of 321 sources. One of the most interesting findings of these surveys was the discovery of three confirmed compact symmetric objects (CSOs) and forty additional candidate CSOs. These are compact (size ~ 100 pc) sources with emission on both sides of the central engine that is thought to be free of beaming effects. To account for their small sizes the CSOs must be either young or severely confined by a dense neutral medium. If these objects are young (ages ~ 3000 yrs) and growing at rates typical of equally luminous, but 1000 times larger, radio galaxies like Cygnus A then they must be a common phase in the evolution of galaxies, or perhaps a recurrent one. Alternatively, if the CSOs are strongly confined and longer lived then the large amount of material required for their confinement should have several observational consequences -- large amounts of neutral and molecular gas, high induced Faraday rotations, and possibly severe reddening and distortions of the starlight from the host galaxy. In an effort to discriminate between the above models we have performed deep infrared imaging of a number of CSOs and CSO candidates. We also report on high-dynamic range imaging with the VLA to look for large Faraday rotation measures, or for extended components that might be the result of a previous active phase. We have also observed one nearby CSO candidate in CO 1-0 with the Owens Valley millimeter array to search for molecular gas.

  9. THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS

    SciTech Connect

    Fong, W.; Berger, E.

    2013-10-10

    We present a detailed investigation of Hubble Space Telescope rest-frame UV/optical observations of 22 short gamma-ray burst (GRB) host galaxies and sub-galactic environments. Utilizing the high angular resolution and depth of HST we characterize the host galaxy morphologies, measure precise projected physical and host-normalized offsets between the bursts and host centers, and calculate the locations of the bursts with respect to their host light distributions (rest-frame UV and optical). We calculate a median short GRB projected physical offset of 4.5 kpc, about 3.5 times larger than that for long GRBs, and find that ≈25% of short GRBs have offsets of ∼> 10 kpc. When compared to their host sizes, the median offset is 1.5 half-light radii (r{sub e} ), about 1.5 times larger than the values for long GRBs, core-collapse supernovae, and Type Ia supernovae. In addition, ≈20% of short GRBs having offsets of ∼> 5r{sub e} , and only ≈25% are located within 1r{sub e} . We further find that short GRBs severely under-represent their hosts' rest-frame optical and UV light, with ≈30%-45% of the bursts located in regions of their host galaxies that have no detectable stellar light, and ≈55% in the regions with no UV light. Therefore, short GRBs do not occur in regions of star formation or even stellar mass. This demonstrates that the progenitor systems of short GRBs must migrate from their birth sites to their eventual explosion sites, a signature of kicks in compact object binary systems. Utilizing the full sample of offsets, we estimate natal kick velocities of ≈20-140 km s{sup –1}. These independent lines of evidence provide the strongest support to date that short GRBs result from the merger of compact object binaries (NS-NS/NS-BH)

  10. Theoretical Study of Compact Objects: Pulsars, Thermally Emitting Neutron Stars and Magnetars

    NASA Astrophysics Data System (ADS)

    Lai, Dong

    This proposal focuses on understanding the various observational manifestations of magnetized neutron stars (NSs), including pulsars, radio-quiet thermally emitting NSs and magnetars. This is motivated by the recent and ongoing observational progress in the study of isolated NSs, made possible by space telescopes such as Chandra and XMM-Newton, and the prospect of near-future observations by NASA's Gravity and Extreme Magnetism SMEX (GEMS) mission (to be launched in 2014). Recent observations have raised a number of puzzles/questions that beg for theoretical understanding and modeling. The proposed research projects are grouped into two parts: (1) Theoretical modeling of surface (or near surface) X-ray emission from magnetized NSs, including the study of the physics of electron/ion cyclotron lines, radiative transfer during magnetar bursts, dense plasma refractive effect, partially ionized atmospheres, and calculations of X-ray polarization signatures of isolated and accreting magnetic NSs, in anticipation of their detections by GEMS. (2) Theoretical study and observational constraint on the internal structure and evolution of magnetic fields in young neutron stars in supernova remnants. The proposed research will improve our understanding of different populations of NSs and their underlying physical processes (including the extreme physics of strong-field quantum electrodynamics) and enhance the scientific return from the current and future NASA astrophysics missions. It is relevant to NASA's objective, ``Discover the origin, structure, evolution, and destiny of the universe''.

  11. Hawaii 167: A compact absorption-line object at z = 2.35

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; Songaila, A.; Hu, E. M.; Egami, E.; Huang, J.-S.; Pickles, A. J.; Ridgway, S. E.; Wainscoat, R. J.; Weymann, R. J.

    1994-01-01

    During the course of the Hawaii K-band (2.1 micrometer) survey we have detected a compact object, Hawaii 167, lying at a redshift of 2.33, in which are seen both low- and high-ionization absorption lines. In the near-infrared we see broad H alpha emission at a redshift of 2.35 but do not detect the other Balmer lines, (O II) lambda 3727, or (O III) lambda 5007. The absence of strong Mg II or C IV emission in the rest ultraviolet suggests that, at these wavelengths, we may be seeing a poststarburst galaxy rather than a quasar. Indeed, this class of object may be common enough to represent a major episode of galaxy formation, possibly the formation of the spheroids. However, Q0059-2735, the most extreme member of the class of Mg II absorbing broad absorption line quasars, is very similar to the present object, and there may be an evolutionary sequence or some other close connection between Hawaii 167 and the broad absorption line quasars.

  12. Study of a new central compact object: The neutron star in the supernova remnant G15.9+0.2

    NASA Astrophysics Data System (ADS)

    Klochkov, D.; Suleimanov, V.; Sasaki, M.; Santangelo, A.

    2016-08-01

    We present our study of the central point source CXOU J181852.0-150213 in the young Galactic supernova remnant (SNR) G15.9+0.2 based on the recent ~90 ks Chandra observations. The point source was discovered in 2005 in shorter Chandra observations and was hypothesized to be a neutron star associated with the SNR. Our X-ray spectral analysis strongly supports the hypothesis of a thermally emitting neutron star associated with G15.9+0.2. We conclude that the object belongs to the class of young cooling low-magnetized neutron stars referred to as central compact objects (CCOs). We modeled the spectrum of the neutron star with a blackbody spectral function and with our hydrogen and carbon neutron star atmosphere models, assuming that the radiation is uniformly emitted by the entire stellar surface. Under this assumption, only the carbon atmosphere models yield a distance that is compatible with a source located in the Galaxy. In this respect, CXOU J181852.0-150213 is similar to two other well-studied CCOs, the neutron stars in Cas A and in HESS J1731-347, for which carbon atmosphere models were used to reconcile their emission with the known or estimated distances.

  13. New code for equilibriums and quasiequilibrium initial data of compact objects. III. Axisymmetric and triaxial rotating stars

    NASA Astrophysics Data System (ADS)

    Uryū, Kōji; Tsokaros, Antonios; Galeazzi, Filippo; Hotta, Hideya; Sugimura, Misa; Taniguchi, Keisuke; Yoshida, Shin'ichirou

    2016-02-01

    We introduce new code for stationary and axisymmetric equilibriums, as well as for triaxial quasiequilibrium initial data, of single rotating relativistic stars. The new code is developed as a part of our versatile initial data code for compact objects, Compact Object CALculator (cocal). In computing strong gravitational fields, the waveless formulation is incorporated into the cocal code on top of the previously developed Isenberg-Wilson-Mathews formulation (conformally flat thin-sandwich formulation). Also introduced is a new differential rotation law that contains two parameters to control an angular velocity profile and a transition from uniform to differential rotation. We present convergence tests and solution sequences for both uniformly and differentially rotating equilibriums of stationary axisymmetric compact stars, as well as for quasiequilibrium initial data of uniformly rotating triaxial (nonaxisymmetric) compact stars. We also show comparisons of uniformly rotating axisymmetric solutions computed with three different codes: cocal, lorene, and the RNS code.

  14. A compact surface decontamination system for surface-sensitive magnetic imaging.

    PubMed

    Konoto, M; Akoh, H; Tokura, Y

    2009-08-01

    A surface decontamination system for application in surface sensitive magnetic imaging tools, such as a spin-polarized scanning electron microscope, is described. Adsorbed contaminant is chemically decomposed with the use of active oxygen in a compact vacuum chamber mounted in a microscope. The present method is especially suitable for fragile magnetic surfaces of complex oxide materials to which the conventional physical etching widely used for magnetic metals could cause serious structural damage. We have succeeded in detecting magnetic signals from a decontaminated oxide surface and visualizing domain images with sufficient magnetic contrast to analyze detailed domain structures. PMID:19725685

  15. Demountable Toroidal Field Magnets for Use in a Compact Modular Fusion Reactor

    NASA Astrophysics Data System (ADS)

    Mangiarotti, F. J.; Goh, J.; Takayasu, M.; Bromberg, L.; Minervini, J. V.; Whyte, D.

    2014-05-01

    A concept of demountable toroidal field magnets for a compact fusion reactor is discussed. The magnets generate a magnetic field of 9.2 T on axis, in a 3.3 m major radius tokamak. Subcooled YBCO conductors have a critical current density adequate to provide this large magnetic field, while operating at 20 K reduces thermodynamic cooling cost of the resistive electrical joints. Demountable magnets allow for vertical replacement and maintenance of internal components, potentially reducing cost and time of maintenance when compared to traditional sector maintenance. Preliminary measurements of contact resistance of a demountable YBCO electrical joint between are presented.

  16. A compact surface decontamination system for surface-sensitive magnetic imaging

    SciTech Connect

    Konoto, M.; Akoh, H.; Tokura, Y.

    2009-08-15

    A surface decontamination system for application in surface sensitive magnetic imaging tools, such as a spin-polarized scanning electron microscope, is described. Adsorbed contaminant is chemically decomposed with the use of active oxygen in a compact vacuum chamber mounted in a microscope. The present method is especially suitable for fragile magnetic surfaces of complex oxide materials to which the conventional physical etching widely used for magnetic metals could cause serious structural damage. We have succeeded in detecting magnetic signals from a decontaminated oxide surface and visualizing domain images with sufficient magnetic contrast to analyze detailed domain structures.

  17. A superconducting bending magnet system for a compact synchrotron light source

    SciTech Connect

    Green, M.A.; Garren, A.A.; Leung, E.M.; Madura, D.D.; Cline, D.B.; Kolonko, J.J.; Schachinger, L.C.

    1995-07-01

    High intensity, high energy X-rays for use in protein crystallography, nano-machining and medical applications, such as non invasive coronary angiography, can be produced by a 1.2 to 1.5 GeV electron storage ring compact light source with 6 to 8 tesla superconducting bending magnets. Because the bending magnets are to be superconducting, the storage ring energy can be over factor of two lower than a conventional storage ring that delivers same photon energy. The ring, which has superconducting bending magnets, is smaller in circumference and has the advantage of having fewer particles in the ring for a given x ray source intensity. The proposed storage ring is a separated function accelerator ring with six superconducting bending magnet units. Conventional quadruples and correction elements would be located between the bending magnets. Because the synchrotron radiation is generated in the bend, the superconducting bending magnets must have a warm vacuum chamber for the electron beam. Variations of a superferric magnet design have been studied for this application. This report presents a superferric H magnet design that can produce good quality magnetic field in a region that is 50 mm high by 100 mm wide. This modified superferric H magnet design has saturated iron poles but the magnetic flux is returned from one pole to the other through an unsaturated iron return path. The dipole magnet required for a compact storage ring must be physically short (380 mm long), and the field must fall off rapidly at the ends of the magnet. This report describes a preliminary design for a pair of 6.894 tesia, thirty degree bending magnets in a common vacuum vessel for use in a 1.5 GeV compact storage ring light source.

  18. A hot compact dust disk around a massive young stellar object.

    PubMed

    Kraus, Stefan; Hofmann, Karl-Heinz; Menten, Karl M; Schertl, Dieter; Weigelt, Gerd; Wyrowski, Friedrich; Meilland, Anthony; Perraut, Karine; Petrov, Romain; Robbe-Dubois, Sylvie; Schilke, Peter; Testi, Leonardo

    2010-07-15

    Circumstellar disks are an essential ingredient of the formation of low-mass stars. It is unclear, however, whether the accretion-disk paradigm can also account for the formation of stars more massive than about 10 solar masses, in which strong radiation pressure might halt mass infall. Massive stars may form by stellar merging, although more recent theoretical investigations suggest that the radiative-pressure limit may be overcome by considering more complex, non-spherical infall geometries. Clear observational evidence, such as the detection of compact dusty disks around massive young stellar objects, is needed to identify unambiguously the formation mode of the most massive stars. Here we report near-infrared interferometric observations that spatially resolve the astronomical-unit-scale distribution of hot material around a high-mass ( approximately 20 solar masses) young stellar object. The image shows an elongated structure with a size of approximately 13 x 19 astronomical units, consistent with a disk seen at an inclination angle of approximately 45 degrees . Using geometric and detailed physical models, we found a radial temperature gradient in the disk, with a dust-free region less than 9.5 astronomical units from the star, qualitatively and quantitatively similar to the disks observed in low-mass star formation. Perpendicular to the disk plane we observed a molecular outflow and two bow shocks, indicating that a bipolar outflow emanates from the inner regions of the system. PMID:20631793

  19. Difficulties in explaining the cosmic photon excess with compact composite object dark matter

    NASA Astrophysics Data System (ADS)

    Cumberbatch, Daniel T.; Starkman, Glenn D.; Silk, Joseph

    2008-03-01

    It has been suggested that dark matter particles are strongly interacting, composite, macroscopically large objects made of well known light quarks (or antiquarks). In doing so it is argued that these compact composite objects (CCOs) provide natural explanations of observed data, such as the 511 keV line from the bulge of our galaxy observed by INTEGRAL, and the excess of diffuse gamma rays in the 1 20 MeV band observed by COMPTEL. Here we argue that the atmospheres of positrons that surround CCOs composed of di-antiquark pairs in the favored color-flavor-locked superconducting state are sufficiently dense as to place stringent limits on the penetration depth of interstellar electrons incident upon them, resulting in an extreme suppression of previously estimated rates of positronium formation, and hence in the flux of 511 keV photons resulting from their subsequent decays. The associated rate of direct electron-positron annihilations, which yield the MeV photons postulated to explain the 1 20 MeV photon excess, is also suppressed. We also discuss how even if a fraction of positrons somehow penetrated the surface of the CCOs, the extremely strong electric fields generated from the bulk antiquark matter would result in the destruction of positronium atoms long before they decay.

  20. Research on anisotropic bonded Nd-Fe-B magnets by 2-step compaction process

    NASA Astrophysics Data System (ADS)

    Ma, Bin; Sun, Aizhi; Lu, Zhenwen; Cheng, Chuan; Xu, Chen

    2016-03-01

    In this paper, a novel 2-step compaction process, called a cold preforming step and a warm alignment and densification step, is proposed to prepare anisotropic bonded Nd-Fe-B magnets with high magnetic properties. The morphology of Nd-Fe-B particles is characterized by scanning electron microscopy. Research shows that the lower the density of preforms, the higher the (BH)max and DOA of Nd-Fe-B magnets. The (BH)max of Nd-Fe-B magnets prepared by 2-step compaction process is higher than that of traditional warm compaction process at the apace rate of 20% when the preform density is lower than 4.06 g/cm3. The (BH)max and DOA first increase and then decline with increasing space rate, the maximum is obtained at the space rate of 25% when the preform density is 3.98 g/cm3. By means of 2-step compaction process, not only (BH)max and DOA of Nd-Fe-B magnets are increased by 32.2% and 61.3% at the space rate of 25%, but also problems such as the easy damage of mould and the inhomogeneous of particle packing are solved, which are in favour of the extension of mould life. The changes of coercivity is not obvious during the research. The mechanrsms of space rate on DOA and density are analyzed and discussed.

  1. Characteristics of trapped magnetic fields in HTS bulk annuli with various axial spaces for compact NMR magnets

    NASA Astrophysics Data System (ADS)

    Kim, S. B.; Imai, M.; Takano, R.; Kashima, K.; Hahn, S.

    2010-11-01

    Recently, the performance of high-temperature superconducting (HTS) bulks such as a critical current density, size, and mechanical strength has been improved. In consequence, various applications with HTS bulks such as motors, bearings, and flywheels are being investigated by many research groups; Compact nuclear magnetic resonance (NMR) magnet is one of the new applications after a technique to enhance maximum trapped field of an HTS bulk more than 11.7 T, 500 MHz 1H NMR frequency, has been developed. This new compact NMR magnet out of HTS bulks is far less expensive than those conventional NMR magnets and expected to be widely used in food and drug industry. In design and manufacture of those compact NMR magnets, the issues of spatial homogeneity and temporal stability of trapped magnetic fields in HTS bulk annuli are very important. In this paper, the characteristics of the trapped magnetic fields in a stack of assembled HTS bulk annuli were investigated with various axial spaces between HTS bulks, experimentally and analytically.

  2. Gravitational radiation from a spinning compact object around a supermassive Kerr black hole in circular orbit

    SciTech Connect

    Han Wenbiao

    2010-10-15

    The gravitational waves and energy radiation from a spinning compact object with stellar mass in a circular orbit in the equatorial plane of a supermassive Kerr black hole are investigated in this paper. The effect of how the spin acts on energy and angular moment fluxes is discussed in detail. The calculation results indicate that the spin of a small body should be considered in waveform-template production for the upcoming gravitational wave detections. It is clear that when the direction of spin axes is the same as the orbitally angular momentum ('positive' spin), spin can decrease the energy fluxes which radiate to infinity. For antidirection spin ('negative'), the energy fluxes to infinity can be enlarged. And the relations between fluxes (both infinity and horizon) and spin look like quadratic functions. From frequency shift due to spin, we estimate the wave-phase accumulation during the inspiraling process of the particle. We find that the time of particle inspiral into the black hole is longer for positive spin and shorter for negative compared with the nonspinning particle. Especially, for extreme spin value, the energy radiation near the horizon of the extreme Kerr black hole is much more than that for the nonspinning one. And consequently, the maximum binging energy of the extreme spinning particle is much larger than that of the nonspinning particle.

  3. VLBA OBSERVATIONS OF H I IN THE ARCHETYPE COMPACT SYMMETRIC OBJECT B2352+495

    SciTech Connect

    Araya, E. D.; Rodriguez, C.; Pihlstroem, Y.; Taylor, G. B.; Tremblay, S.; Vermeulen, R. C.

    2010-01-15

    B2352+495 is a prototypical example of a compact symmetric object. It has a double radio lobe symmetrically located with respect to a central flat-spectrum radio core (the location of the active galactic nucleus) and has a physical extent of less than 200 pc. In this work, we report Very Long Baseline Array observation of 21 cm H I absorption toward B2352+495 to investigate the properties of this remarkable radio source, in particular, to explore whether the radio emission can be confined by circumnuclear material (frustration scenario) or whether the source is likely to be young. We confirmed the two H I absorption features previously detected toward B2352+495-a broad line nearly centered at the systemic velocity of the galaxy and a narrow redshifted component. The atomic gas from the broad absorption component is likely associated with circumnuclear material, consistent with the current paradigm of clumpy H I distribution in toroidal structures around supermassive black holes.

  4. Compact objects at the heart of outflows in large and small systems

    NASA Astrophysics Data System (ADS)

    Sell, Paul Harrison

    2013-12-01

    This thesis focuses on studying and assessing high-energy feedback generated by both stellar mass and supermassive compact objects. From these two perspectives, I help bridge the gap in understanding how jets and winds can transform their much larger environments in thousands to millions of years, astronomically short timescales. I have acquired X-ray and optical data that aim to elucidate the role these objects play in powering parsec-scale shockwaves in the ISM and in driving kiloparsec-scale outflows in galaxies. I present Chandra X-ray imaging, Hubble Space Telescope imaging, and WIYN Hydra multi-object optical spectroscopic observations. The data reveal the morphologies of the systems and constrain on a range of interesting parameters: power, outflow velocity, density, accretion efficiency, and timescale. My analysis provides perspective on the importance of black holes, both large and small, and neutron stars for driving outflows into the interstellar and intergalactic medium. On kiloparsec scales, I explore the nature of what appear to be merging or recently merging post-starburst galaxies with very high-velocity winds. This work is part of a multiwavelength effort to characterize the niche these galaxies fill in the larger scheme of galaxy evolution. My focus is on the accretion activity of the coalescing supermassive black holes in their cores. This work leads us to compare the relative importance of a massive starburst to the supermassive black holes in the cores of the galaxies. On parsec scales, I present case studies of two prominent microquasars, Galactic X-ray binaries with jets, Circinus X-1 and Cygnus X-1. In the case of Circinus X-1, I present very deep follow-up observations of parsec-scale shock plumes driven by a powerful, bipolar jet. In the case of Cygnus X-1, I present follow-up observations to probe a recently discovered outflow near the binary. I calculate robust, physically motivated limits on the total power needed to drive the outflows

  5. Study and Developement of Compact Permanent Magnet Hall Thrusters for Future Brazillian Space Missions

    NASA Astrophysics Data System (ADS)

    Ferreira, Jose Leonardo; Martins, Alexandre; Cerda, Rodrigo

    2016-07-01

    . The main difficulty to reach these minor bodies is related to their specific orbits with high eccentricity and inclination. A good example is the case for sample return missions to NEOs-Near Earth Objects. They are small bodies consisting of primitive left over building blocks of the Solar System formation processes. These missions can be accomplished by using low thrust trajectories with spacecrafts propelled by plasma thrusters with total thrust below 0.5 N, and a specific impulse around2500 s. In this work, we will show the brazilian contribution to the development of a compact electrical propulsion engine named PHALL III, designed with DCFH and foreseen to be used in future cubesats microsatellites but with possible applications in geostationary attitude control systems and on low thrust trajectory missions to the Near Earth Asteroids region. We will show a particular new permanent magnet field designed for PHALL III . Computer based simulation codes such as VSIM are also used on the design of this new proposed cuped magnet field Hall Thruster. Based on the first results wee believed PHALL III will also allow a good spacecraft performance of long duration space missions for small size spacecrafts with limited low electric source power consumption. The PHALL III plasma source characterization is presented together with the ejected plasma plume ion current intensity, ion energy and plasma flow velocity parameters measured by an integrated Plasma Diagnostic Bench (BID). Based on plasma source and plume ejected parameters a merit figure of PHALL III is constructed and compared to computer calculated low thrust transfer requirements. From these results it is goig to be possible to analyse the potential use of PHALL III on future brazillian space missions , its working parameters are compared with parameters of existing space tested plasma thrusters already used on moon , deep space missions and also on satellite geostationary positioning using low thrust orbit

  6. DOUBLE COMPACT OBJECTS. I. THE SIGNIFICANCE OF THE COMMON ENVELOPE ON MERGER RATES

    SciTech Connect

    Dominik, Michal; Belczynski, Krzysztof; Bulik, Tomasz; Fryer, Christopher; Holz, Daniel E.; Berti, Emanuele; Mandel, Ilya; O'Shaughnessy, Richard

    2012-11-01

    The last decade of observational and theoretical developments in stellar and binary evolution provides an opportunity to incorporate major improvements to the predictions from population synthesis models. We compute the Galactic merger rates for NS-NS, BH-NS, and BH-BH mergers with the StarTrack code. The most important revisions include updated wind mass-loss rates (allowing for stellar-mass black holes up to 80 M {sub Sun }), a realistic treatment of the common envelope phase (a process that can affect merger rates by 2-3 orders of magnitude), and a qualitatively new neutron star/black hole mass distribution (consistent with the observed {sup m}ass gap{sup )}. Our findings include the following. (1) The binding energy of the envelope plays a pivotal role in determining whether a binary merges within a Hubble time. (2) Our description of natal kicks from supernovae plays an important role, especially for the formation of BH-BH systems. (3) The masses of BH-BH systems can be substantially increased in the case of low metallicities or weak winds. (4) Certain combinations of parameters underpredict the Galactic NS-NS merger rate and can be ruled out. (5) Models incorporating delayed supernovae do not agree with the observed NS/BH 'mass gap', in accordance with our previous work. This is the first in a series of three papers. The second paper will study the merger rates of double compact objects as a function of redshift, star formation rate, and metallicity. In the third paper, we will present the detection rates for gravitational-wave observatories, using up-to-date signal waveforms and sensitivity curves.

  7. UNDERSTANDING COMPACT OBJECT FORMATION AND NATAL KICKS. III. THE CASE OF CYGNUS X-1

    SciTech Connect

    Wong, Tsing-Wai; Valsecchi, Francesca; Kalogera, Vassiliki; Fragos, Tassos E-mail: francesca@u.northwestern.edu E-mail: tfragos@cfa.harvard.edu

    2012-03-10

    In recent years, accurate observational constraints have become available for an increasing number of Galactic X-ray binaries (XRBs). Together with proper-motion measurements, we could reconstruct the full evolutionary history of XRBs back to the time of compact object formation. In this paper, we present the first study of the persistent X-ray source Cygnus X-1 that takes into account all available observational constraints. Our analysis accounts for three evolutionary phases: orbital evolution and motion through the Galactic potential after the formation of a black hole (BH), and binary orbital dynamics at the time of core collapse. We find that the mass of the BH immediate progenitor is 15.0-20.0 M{sub Sun }, and at the time of core collapse, the BH has potentially received a small kick velocity of {<=}77 km s{sup -1} at 95% confidence. If the BH progenitor mass is less than {approx}17 M{sub Sun }, a non-zero natal kick velocity is required to explain the currently observed properties of Cygnus X-1. Since the BH has only accreted mass from its companion's stellar wind, the negligible amount of accreted mass does not explain the observationally inferred BH spin of a{sub *} > 0.95, and the origin of this extreme BH spin must be connected to the BH formation itself. Right after the BH formation, we find that the BH companion is a 19.8-22.6 M{sub Sun} main-sequence star, orbiting the BH at a period of 4.7-5.2 days. Furthermore, recent observations show that the BH companion is currently super-synchronized. This super-synchronism indicates that the strength of tides exerted on the BH companion should be weaker by a factor of at least two compared to the usually adopted strength.

  8. New constraints on the cooling of the central compact object in CAS A

    SciTech Connect

    Posselt, B.; Pavlov, G. G.; Suleimanov, V.; Kargaltsev, O.

    2013-12-20

    To examine the previously claimed fast cooling of the Central Compact Object (CCO) in the Cas A supernova remnant (SNR), we analyzed two Chandra observations of this CCO, taken in a setup minimizing instrumental spectral distortions. We fit the two CCO X-ray spectra from 2006 and 2012 with hydrogen and carbon neutron star atmosphere models. The temperature and flux changes in the 5.5 yr between the two epochs depend on the adopted constraints on the fitting parameters and the uncertainties of the effective area calibrations. If we allow a change of the equivalent emitting region size, R {sub Em}, the effective temperature remains essentially the same. If R {sub Em} is held constant, the best-fit temperature change is negative, but its statistical significance ranges from 0.8σ to 2.5σ, depending on the model. If we assume that the optical depth of the ACIS filter contaminant in 2012 was ±10% different from its default calibration value, the significance of the temperature drop becomes 0.8σ-3.1σ, for the carbon atmospheres with constant R {sub Em}. Thus, we do not see a statistically significant temperature drop in our data, but the involved uncertainties are too large to firmly exclude the previously reported fast cooling. Our analysis indicate a decrease of 4%-6% (1.9σ-2.9σ significance) for the absorbed flux in the energy range 0.6-6 keV between 2006 and 2012, most prominent in the ≈1.4-1.8 keV energy range. It could be caused by unaccounted changes of the detector response or contributions from unresolved SNR material along the line of sight to the CCO.

  9. Development of magnetic fabric in sedimentary rocks: insights from early compactional structures

    NASA Astrophysics Data System (ADS)

    García-Lasanta, Cristina; Oliva-Urcia, Belén; Román-Berdiel, Teresa; Casas, Antonio M.; Pérez-Lorente, Félix

    2013-07-01

    The timing of development of the magnetic fabric is a major issue in the application of anisotropy of magnetic susceptibility (AMS) as a strain marker. Analysis of AMS in unconcealed synsedimentary structures can be a sound approximation to this task. In this work, three types of early compactional structures (ECS) were studied by means of AMS, since they can help to understand the timing of development of the magnetic fabric. All three types of ECS are found in fine-grained detrital rocks (to avoid other influences such as palaeocurrents), claystones and marls of the Enciso Group within the Cameros Basin (NE Spain): dinosaur footprints, load structures due to differential compaction and dish-and-flame structures associated with fluid migration related to seismites. In addition, to determine possible influences of lithology on the magnetic fabric, different rock types (siltstones and limestones) were also sampled. In general, the influence of ECS results in scattering of the three magnetic axes, higher at the margins of the structure than at its centre. This fact suggests that ECS occurs during the development of the magnetic fabric, disturbing the incipient magnetic fabric stages, and strongly conditions its later evolution during diagenesis. The later homogeneous compaction process due to sedimentary load and physicochemical processes reorient the susceptibility carriers to some extent (i.e. the magnetic fabric is still under development), but not totally, since AMS still records the previous scattering due to ECS imprint. For the Enciso Group deposits, the magnetic fabric begins to develop at the earliest stages after deposition and it stops when diagenetic processes have finished.

  10. Development of a compact magnetic proton recoil spectrometer for measurement of deuterium-tritium neutrons.

    PubMed

    Zhang, Jianfu; Ouyang, Xiaoping; Qiu, Suizheng; Zhang, Guoguang; Ruan, Jinlu; Zhang, Xiaodong; Zhang, Xianpeng; Yang, Shaohua; Song, Jiwen; Liu, Linyue; Li, Hongyun

    2015-12-01

    A new compact magnetic proton recoil (MPR) neutron spectrometer has been designed for precise measurement of deuterium-tritium (DT) neutrons. This design is presented emphasizing the magnetic analyzing system, which is based on a compact quadrupole-dipole (QD) electromagnet. The focal plane detector (FPD) is also discussed with respect to application for the next step. The characteristics of the MPR spectrometer were calculated by using Monte Carlo simulation. A preliminary experiment was performed to test the magnetic analyzing system and the proton images of the FPD. Since the QD electromagnet design allows for a larger foil thickness and solid angle to be utilized, the MPR spectrometer defined in this paper can achieve neutron detection efficiency more than 5 × 10(-7) at an energy resolution of 1.5% for measuring DT neutrons. PMID:26724081

  11. Development of a compact magnetic proton recoil spectrometer for measurement of deuterium-tritium neutrons

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfu; Ouyang, Xiaoping; Qiu, Suizheng; Zhang, Guoguang; Ruan, Jinlu; Zhang, Xiaodong; Zhang, Xianpeng; Yang, Shaohua; Song, Jiwen; Liu, Linyue; Li, Hongyun

    2015-12-01

    A new compact magnetic proton recoil (MPR) neutron spectrometer has been designed for precise measurement of deuterium-tritium (DT) neutrons. This design is presented emphasizing the magnetic analyzing system, which is based on a compact quadrupole-dipole (QD) electromagnet. The focal plane detector (FPD) is also discussed with respect to application for the next step. The characteristics of the MPR spectrometer were calculated by using Monte Carlo simulation. A preliminary experiment was performed to test the magnetic analyzing system and the proton images of the FPD. Since the QD electromagnet design allows for a larger foil thickness and solid angle to be utilized, the MPR spectrometer defined in this paper can achieve neutron detection efficiency more than 5 × 10-7 at an energy resolution of 1.5% for measuring DT neutrons.

  12. Development of a compact permanent magnet helicon plasma source for ion beam bioengineering

    SciTech Connect

    Kerdtongmee, P.; Srinoum, D.; Nisoa, M.

    2011-10-15

    A compact helicon plasma source was developed as a millimeter-sized ion source for ion beam bioengineering. By employing a stacked arrangement of annular-shaped permanent magnets, a uniform axial magnetic flux density up to 2.8 kG was obtained. A cost effective 118 MHz RF generator was built for adjusting forward output power from 0 to 40 W. The load impedance and matching network were then analyzed. A single loop antenna and circuit matching elements were placed on a compact printed circuit board for 50 {Omega} impedance matching. A plasma density up to 1.1 x 10{sup 12} cm{sup -3} in the 10 mm diameter tube under the magnetic flux density was achieved with 35 W applied RF power.

  13. Development of a compact permanent magnet helicon plasma source for ion beam bioengineering.

    PubMed

    Kerdtongmee, P; Srinoum, D; Nisoa, M

    2011-10-01

    A compact helicon plasma source was developed as a millimeter-sized ion source for ion beam bioengineering. By employing a stacked arrangement of annular-shaped permanent magnets, a uniform axial magnetic flux density up to 2.8 kG was obtained. A cost effective 118 MHz RF generator was built for adjusting forward output power from 0 to 40 W. The load impedance and matching network were then analyzed. A single loop antenna and circuit matching elements were placed on a compact printed circuit board for 50 Ω impedance matching. A plasma density up to 1.1 × 10(12) cm(-3) in the 10 mm diameter tube under the magnetic flux density was achieved with 35 W applied RF power. PMID:22047290

  14. Development of a compact magnetic proton recoil spectrometer for measurement of deuterium-tritium neutrons

    SciTech Connect

    Zhang, Jianfu Ouyang, Xiaoping; Zhang, Xianpeng; Qiu, Suizheng; Zhang, Guoguang; Ruan, Jinlu; Zhang, Xiaodong; Yang, Shaohua; Song, Jiwen; Liu, Linyue; Li, Hongyun

    2015-12-15

    A new compact magnetic proton recoil (MPR) neutron spectrometer has been designed for precise measurement of deuterium-tritium (DT) neutrons. This design is presented emphasizing the magnetic analyzing system, which is based on a compact quadrupole-dipole (QD) electromagnet. The focal plane detector (FPD) is also discussed with respect to application for the next step. The characteristics of the MPR spectrometer were calculated by using Monte Carlo simulation. A preliminary experiment was performed to test the magnetic analyzing system and the proton images of the FPD. Since the QD electromagnet design allows for a larger foil thickness and solid angle to be utilized, the MPR spectrometer defined in this paper can achieve neutron detection efficiency more than 5 × 10{sup −7} at an energy resolution of 1.5% for measuring DT neutrons.

  15. Calibration of a compact magnetic proton recoil neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfu; Ouyang, Xiaoping; Zhang, Xianpeng; Ruan, Jinlu; Zhang, Guoguang; Zhang, Xiaodong; Qiu, Suizheng; Chen, Liang; Liu, Jinliang; Song, Jiwen; Liu, Linyue; Yang, Shaohua

    2016-04-01

    Magnetic proton recoil (MPR) neutron spectrometer is considered as a powerful instrument to measure deuterium-tritium (DT) neutron spectrum, as it is currently used in inertial confinement fusion facilities and large Tokamak devices. The energy resolution (ER) and neutron detection efficiency (NDE) are the two most important parameters to characterize a neutron spectrometer. In this work, the ER calibration for the MPR spectrometer was performed by using the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), and the NDE calibration was performed by using the neutron generator at CIAE. The specific calibration techniques used in this work and the associated accuracies were discussed in details in this paper. The calibration results were presented along with Monte Carlo simulation results.

  16. A Dedicated Genetic Algorithm for Localization of Moving Magnetic Objects

    PubMed Central

    Alimi, Roger; Weiss, Eyal; Ram-Cohen, Tsuriel; Geron, Nir; Yogev, Idan

    2015-01-01

    A dedicated Genetic Algorithm (GA) has been developed to localize the trajectory of ferromagnetic moving objects within a bounded perimeter. Localization of moving ferromagnetic objects is an important tool because it can be employed in situations when the object is obscured. This work is innovative for two main reasons: first, the GA has been tuned to provide an accurate and fast solution to the inverse magnetic field equations problem. Second, the algorithm has been successfully tested using real-life experimental data. Very accurate trajectory localization estimations were obtained over a wide range of scenarios. PMID:26393598

  17. HST observations of the nebula around the central compact object in the Vela Jr. supernova remnant

    NASA Astrophysics Data System (ADS)

    Mignani, R. P.; de Luca, A.; Pellizzoni, A.

    2009-12-01

    Context: A handful of young (a few thousand years) supernova remnants (SNRs) host point-like X-ray sources, dubbed central compact objects (CCOs), which are thought to be radio-silent isolated neutron stars formed by the supernova explosion. So far, no CCO has been firmly detected at other wavelengths. However, ground-based observation in the Hα band detected a nebula around CXO J085201.4-461753, the CCO in the Vela Jr. SNR. The nebula has also been detected in deep R-band observations performed with the Very Large Telescope (VLT). Interestingly, both its extension and its flux in the R band are consistent with those measured in Hα, suggesting that the nebula spectrum is dominated by line emission, possibly produced by a velocity-driven bow-shock in the interstellar medium (ISM) or by its photo-ionisation from the neutron star. Aims: The aim of this work is to resolve the morphology of the Hα nebula around the CCO to verify the proposed interpretations. Methods: We performed high-resolution imaging observations of the nebula with the Wide Field Planetary Camera 2 (WFPC2) of the Hubble Space Telescope (HST) through the 656N filter, almost exactly centred on the rest wavelength of the Hα line. Results: Surprisingly enough, we did not detect the nebula in our WFPC2 image down to a 3 σ flux limit of ~3 × 10-15 erg cm-2 s-1. This limit is a factor of 10 fainter than the nebula flux measured in the discovery ground-based observations which were, however, performed with redder and broader Hα filters. Conclusions: The non-detection of the nebula in the narrower and bluer WFPC2 656N filter suggests that the peak of the emission might actually be at longer wavelengths. One possibility, compatible with the bow-shock scenario only, is that the Hα line is red-shifted by ~10-60 Å due to the neutron star motion with a radial velocity 450 ⪉ Vr ⪉ 2700 km s-1. The other possibility is that the nebula is a knot of [NII] emission (λ = 6583.6 Å) unrelated to CXO J085201

  18. The multimessenger picture of compact object encounters: binary mergers versus dynamical collisions

    NASA Astrophysics Data System (ADS)

    Rosswog, S.; Piran, T.; Nakar, E.

    2013-04-01

    We explore the multimessenger signatures of encounters between two neutron stars (ns2) and between a neutron star and a stellar mass black hole (nsbh). We focus on the differences between gravitational-wave-driven binary mergers and dynamical collisions that occur, for example, in globular clusters. Our discussion is based on Newtonian hydrodynamics simulations that incorporate a nuclear equation of state and a multiflavour neutrino treatment. For both types of encounters we compare the gravitational wave and neutrino emission properties. We also calculate the rates at which nearly unbound mass is delivered back to the central remnant in a ballistic-fallback-plus-viscous-disc model and we analyse the properties of the dynamically ejected matter. Last but not least we address the electromagnetic transients that accompany each type of encounter. We find that dynamical collisions are at least as promising as binary mergers for producing (short) gamma-ray bursts, but they also share the same possible caveats in terms of baryonic pollution. All encounter remnants produce peak neutrino luminosities of at least ˜1053 erg s-1, some of the collision cases exceed this value by more than an order of magnitude. The canonical ns2 merger case ejects more than 1 per cent of a solar mass of extremely neutron-rich (Ye ˜ 0.03) material, an amount that is consistent with double neutron star mergers being a major source of r-process in the galaxy. nsbh collisions eject very large amounts of matter (˜0.15 M⊙) which seriously constrains their admissible occurrence rates. The compact object collision rate (sum of ns2 and nsbh) must therefore be less, likely much less, than 10 per cent of the ns2 merger rate. The radioactively decaying ejecta produce optical-ultraviolet `macronova' which, for the canonical merger case, peak after ˜0.4 d with a luminosity of ˜5 × 1041 erg s-1. ns2 (nsbh) collisions reach up to two (four) times larger peak luminosities. The dynamic ejecta deposit a

  19. A Compact, High-Performance Continuous Magnetic Refrigerator

    NASA Technical Reports Server (NTRS)

    Shirron, Peter; Canavan, Edgar; DiPirro, Michael; Jackson, Michael; King, Todd; Panek, John; Tuttle, James; Brodeur, Stephen J. (Technical Monitor)

    2001-01-01

    We present test results of the first adiabatic demagnetization refrigerator (ADR) that can produce continuous cooling at sub-kelvin temperatures. This system uses multiple stages that operate in sequence to cascade heat from a continuous stage up to a heat sink. Continuous operation aids the usual constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, and allows us to achieve much higher cooling power per unit mass. Our design goal is 10 microW of cooling at 50 mK while rejecting heat to a 6-10 K heat sink. The total cold mass is estimated to be less than 10 kg, including magnetic shielding of each stage. These parameters envelop the requirements for currently planned astronomy missions. The relatively high heat rejection capability allows it to operate with a mechanical cryocooler as part of a cryogen-free, low temperature cooling system. This has the advantages of long, mission life and reduced complexity and cost. At present, we have assembled a three-stage ADR that operates with a superfluid helium bath. Additional work is underway to develop magnetocaloric materials that can extend its heat rejection capability up to 10 K. This paper discusses the design and operation of the ADR, as well as interface requirements for cryocooler-based operation.

  20. A new design for a compact centrifugal blood pump with a magnetically levitated rotor.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2004-01-01

    A compact centrifugal blood pump has been developed using a radial magnetic bearing with a two-degree of freedom active control. The proposed magnetic bearing exhibits high stiffness, even in passively controlled directions, and low power consumption because a permanent magnet, incorporated with the rotor, suspends its weight. The rotor is driven by a Lorentz force type of built-in motor, avoiding mechanical friction and material wear. The built-in motor is designed to generate only rotational torque, without radial and axial attractive forces on the rotor, leading to low power consumption by the magnetic bearing. The fabricated centrifugal pump measured 65 mm in diameter and 45 mm in height and weighed 0.36 kg. In the closed loop circuit filled with water, the pump provided a flow rate of 4.5 L/min at 2,400 rpm against a pressure head of 100 mm Hg. Total power consumption at that point was 18 W, including 2 W required for magnetic levitation, with a total efficiency of 5.7%. The experimental results showed that the design of the compact magnetic bearing was feasible and effective for use in a centrifugal blood pump. PMID:15672787

  1. A Comprehensive Study of Binary Compact Objects as Gravitational Wave Sources: Evolutionary Channels, Rates, and Physical Properties

    NASA Astrophysics Data System (ADS)

    Belczynski, Krzysztof; Kalogera, Vassiliki; Bulik, Tomasz

    2002-06-01

    A new generation of ground-based interferometric detectors for gravitational waves is currently under construction or has entered the commissioning phase (Laser Interferometer Gravitational-wave Observatory [LIGO], VIRGO, GEO600, TAMA300). The purpose of these detectors is to observe gravitational waves from astrophysical sources and help improve our understanding of the source origin and physical properties. In this paper we study the most promising candidate sources for these detectors: inspiraling double compact objects. We use population synthesis methods to calculate the properties and coalescence rates of compact object binaries: double neutron stars, black hole-neutron star systems, and double black holes. We also examine the formation channels available to double compact object binaries. We explicitly account for the evolution of low-mass helium stars and investigate the possibility of common-envelope evolution involving helium stars as well as two evolved stars. As a result we identify a significant number of new formation channels for double neutron stars, in particular, leading to populations with very distinct properties. We discuss the theoretical and observational implications of such populations, but we also note the need for hydrodynamical calculations to settle the question of whether such common-envelope evolution is possible. We also present and discuss the physical properties of compact object binaries and identify a number of robust, qualitative features as well as their origin. Using the calculated coalescence rates we compare our results to earlier studies and derive expected detection rates for LIGO. We find that our most optimistic estimate for the first LIGO detectors reach a couple of events per year and our most pessimistic estimate for advanced LIGO detectors exceed ~=10 events per year.

  2. Compact permanent magnet H+ ECR ion source with pulse gas valve

    NASA Astrophysics Data System (ADS)

    Iwashita, Y.; Tongu, H.; Fuwa, Y.; Ichikawa, M.

    2016-02-01

    Compact H+ ECR ion source using permanent magnets is under development. Switching the hydrogen gas flow in pulse operations can reduce the gas loads to vacuum evacuation systems. A specially designed piezo gas valve chops the gas flow quickly. A 6 GHz ECR ion source equipped with the piezo gas valve is tested. The gas flow was measured by a fast ion gauge and a few ms response time is obtained.

  3. Compact Integration of a GSM-19 Magnetic Sensor with High-Precision Positioning using VRS GNSS Technology.

    PubMed

    Martín, Angel; Padín, Jorge; Anquela, Ana Belén; Sánchez, Juán; Belda, Santiago

    2009-01-01

    Magnetic data consists of a sequence of collected points with spatial coordinates and magnetic information. The spatial location of these points needs to be as exact as possible in order to develop a precise interpretation of magnetic anomalies. GPS is a valuable tool for accomplishing this objective, especially if the RTK approach is used. In this paper the VRS (Virtual Reference Station) technique is introduced as a new approach for real-time positioning of magnetic sensors. The main advantages of the VRS approach are, firstly, that only a single GPS receiver is needed (no base station is necessary), reducing field work and equipment costs. Secondly, VRS can operate at distances separated 50-70 km from the reference stations without degrading accuracy. A compact integration of a GSM-19 magnetometer sensor with a geodetic GPS antenna is presented; this integration does not diminish the operational flexibility of the original magnetometer and can work with the VRS approach. The coupled devices were tested in marshlands around Gandia, a city located approximately 100 km South of Valencia (Spain), thought to be the site of a Roman cemetery. The results obtained show adequate geometry and high-precision positioning for the structures to be studied (a comparison with the original low precision GPS of the magnetometer is presented). Finally, the results of the magnetic survey are of great interest for archaeological purposes. PMID:22574055

  4. Magnetized plasma flow injection into tokamak and high-beta compact torus plasmas

    NASA Astrophysics Data System (ADS)

    Matsunaga, Hiroyuki; Komoriya, Yuuki; Tazawa, Hiroyasu; Asai, Tomohiko; Takahashi, Tsutomu; Steinhauer, Loren; Itagaki, Hirotomo; Onchi, Takumi; Hirose, Akira

    2010-11-01

    As an application of a magnetized coaxial plasma gun (MCPG), magnetic helicity injection via injection of a highly elongated compact torus (magnetized plasma flow: MPF) has been conducted on both tokamak and field-reversed configuration (FRC) plasmas. The injected plasmoid has significant amounts of helicity and particle contents and has been proposed as a fueling and a current drive method for various torus systems. In the FRC, MPF is expected to generate partially spherical tokamak like FRC equilibrium by injecting a significant amount of magnetic helicity. As a circumstantial evidence of the modified equilibrium, suppressed rotational instability with toroidal mode number n = 2. MPF injection experiments have also been applied to the STOR-M tokamak as a start-up and current drive method. Differences in the responses of targets especially relation with beta value and the self-organization feature will be studied.

  5. Proceedings of the third symposium on the physics and technology of compact toroids in the magnetic fusion energy program

    SciTech Connect

    Siemon, R.E.

    1981-03-01

    This document contains papers contributed by the participants of the Third Symposium on Physics and Technology of Compact Toroids in the Magnetic Fusion Energy Program. Subjects include reactor aspects of compact toroids, energetic particle rings, spheromak configurations (a mixture of toroidal and poloidal fields), and field-reversed configurations (FRC's that contain purely poloidal field).

  6. Object representation and magnetic moments in thin alkali films

    NASA Astrophysics Data System (ADS)

    Garrett, Douglas C.

    2008-10-01

    This thesis is broken into two parts a computer vision part and a solid state physics part. In the computer vision part of the thesis (chapters 1 through 5), the concept of an architecture is discussed with a review of what is known about the brain's visual architecture as it applies to object representation. With this in mind we review the two main types of architectures that are used in computer vision for object representation. A specific object representation is then implemented and optimized to solve a problem in object tracking. This representation is then used to derive the fiducial points of a face using two distinct methods. One using evolutionary algorithms and another by a Bayesian analysis of the feature responses drawn from a gallery of faces. The evolved fiducial representation is tested as a facial detection system. It is shown that the Bayesian analysis of facial images gives an entropy measure that can be used to further improve detection results in the facial detection system. In addition, two similarity metrics are explored in the context of facial detection. It is found that a normalized vector dot product substantially outperforms the Euclidean distance measure. The solid state part of the thesis is composed of two self contained chapters. An effort has been made to reduce the redundancies between the material but some will necessarily remain (i.e., short descriptions of the experimental setup). Both chapters deal with the phenomenon of magnetism of atomic impurities in and on thin metal host films. The important difference between the chapters, besides the results, lies in the experimental technique used to measure the magnetism. In chapter 6, thin films of Pb are covered in situ with sub monolayers of V, Mo and Co in the range between 0.01 and 1 monolayers. If the surface impurities are magnetic they will reduce the superconducting transition temperature of the Pb film. From the reduction of Tc the magnetic dephasing rate of the surface

  7. Parameter Estimation Using Markov Chain Monte Carlo Methods for Gravitational Waves from Spinning Inspirals of Compact Objects

    NASA Astrophysics Data System (ADS)

    Raymond, Vivien

    2012-05-01

    Gravitational waves are on the verge of opening a brand new window on the Universe. However, gravitational wave astronomy comes with very unique challenges in data analysis and signal processing in order to lead to new discoveries in astrophysics. Among the sources of gravitational waves, inspiraling binary systems of compact objects, neutron stars and/or black holes in the mass range 1Msun--100Msun stand out as likely to be detected and relatively easy to model. The detection of a gravitational wave event is challenging and will be a rewarding achievement by itself. After such a detection, measurement of source properties holds major promise for improving our astrophysical understanding and requires reliable methods for parameter estimation and model selection. This is a complicated problem, because of the large number of parameters (15 for spinning compact objects in a quasi-circular orbit) and the degeneracies between them, the significant amount of structure in the parameter space, and the particularities of the detector noise. This work presents the development of a parameter-estimation and model-selection algorithm, based on Bayesian statistical theory and using Markov chain Monte Carlo methods for ground-based gravitational-wave detectors (LIGO and Virgo). This method started from existing non-spinning and single spin stand-alone analysis codes and was developed into a method able to tackle the complexity of fully spinning systems, and infer all spinning parameters of a compact binary. Not only are spinning parameters believed to be astrophysically significant, but this work has shown that not including them in the analysis can lead to biases in parameter recovery. This work made it possible to answer several scientific questions involving parameter estimation of inspiraling spinning compact objects, which are addressed in the chapters of this dissertation.

  8. Real-time imaging of moving living objects using a compact terahertz scanner

    NASA Astrophysics Data System (ADS)

    Han, Sang-Pil; Kim, Namje; Lee, Won-Hui; Lee, Eui Su; Ko, Hyunsung; Lee, Il-Min; Moon, Kiwon; Lee, Dong Hun; Park, Kyung Hyun

    2016-02-01

    In this study, we design a compact terahertz (THz) reflection scanner with a scan rate of 20 frames/s. This scanner is based on a benzocyclobutene-embedded InGaAs Schottky barrier diode detector having a maximum responsivity of 300 V/W at 250 GHz and a minimum noise equivalent power of 38 pW/\\sqrt{\\text{Hz}} . With this scanner, details such as sharp head and tail and wrinkled segments in a moving caterpillar are observed. The thin and thick parts of the moving caterpillar that are presented in light gray and dark gray, respectively, on the gray scale are also well distinguished.

  9. Magnetic field structure around cores with very low luminosity objects

    NASA Astrophysics Data System (ADS)

    Soam, A.; Maheswar, G.; Lee, Chang Won; Dib, Sami; Bhatt, H. C.; Tamura, Motohide; Kim, Gwanjeong

    2015-01-01

    Aims: We carried out optical polarimetry of five dense cores, (IRAM 04191, L1521F, L328, L673-7, and L1014) which are found to harbour very low luminosity objects (VeLLOs; Lint ≲ 0.1 L⊙). This study was conducted mainly to understand the role played by the magnetic field in the formation of very low and substellar mass range objects. Methods: Light from the stars, while passing through the dust grains that are aligned with their short axis parallel to an external magnetic field, becomes linearly polarised. The polarisation position angles measured for the stars can provide the plane-of-the sky magnetic field orientation. Because the light in the optical wavelength range is most efficiently polarised by the dust grains typically found at the outer layers of the molecular clouds, optical polarimetry mostly traces the magnetic field orientation of the core envelope. Results: The polarisation observations of stars projected on IRAM 04191, L328, L673-7, and L1014 were obtained in the R-band and those of L1521F were obtained in the V-band. The angular offsets between the envelope magnetic field direction (inferred from optical polarisation measurements) and the outflow position angles from the VeLLOs in IRAM 04191, L1521F, L328, L673-7, and L1014 are found to be 84°, 53°, 24°, 08°, and 15°, respectively. The mean value of the offsets for all the five clouds is ~ 37°. If we exclude IRAM 04191, the mean value reduces to become ~ 25°. In IRAM 04191, the offset between the projected envelope and the inner magnetic field (inferred from the submillimetre data obtained using SCUBA-POL) is found to be ~ 68°. The inner magnetic field, however, is found to be nearly aligned with the projected position angles of the minor axis, the rotation axis of the cloud, and the outflow from the IRAM 04191-IRS. We discuss a possible explanation for the nearly perpendicular orientation between the envelope and core scale magnetic fields in IRAM 04191. The angular offset between the

  10. Study and Developement of Compact Permanent Magnet Hall Thrusters for Future Brazillian Space Missions

    NASA Astrophysics Data System (ADS)

    Ferreira, Jose Leonardo; Martins, Alexandre; Cerda, Rodrigo

    2016-07-01

    . The main difficulty to reach these minor bodies is related to their specific orbits with high eccentricity and inclination. A good example is the case for sample return missions to NEOs-Near Earth Objects. They are small bodies consisting of primitive left over building blocks of the Solar System formation processes. These missions can be accomplished by using low thrust trajectories with spacecrafts propelled by plasma thrusters with total thrust below 0.5 N, and a specific impulse around2500 s. In this work, we will show the brazilian contribution to the development of a compact electrical propulsion engine named PHALL III, designed with DCFH and foreseen to be used in future cubesats microsatellites but with possible applications in geostationary attitude control systems and on low thrust trajectory missions to the Near Earth Asteroids region. We will show a particular new permanent magnet field designed for PHALL III . Computer based simulation codes such as VSIM are also used on the design of this new proposed cuped magnet field Hall Thruster. Based on the first results wee believed PHALL III will also allow a good spacecraft performance of long duration space missions for small size spacecrafts with limited low electric source power consumption. The PHALL III plasma source characterization is presented together with the ejected plasma plume ion current intensity, ion energy and plasma flow velocity parameters measured by an integrated Plasma Diagnostic Bench (BID). Based on plasma source and plume ejected parameters a merit figure of PHALL III is constructed and compared to computer calculated low thrust transfer requirements. From these results it is goig to be possible to analyse the potential use of PHALL III on future brazillian space missions , its working parameters are compared with parameters of existing space tested plasma thrusters already used on moon , deep space missions and also on satellite geostationary positioning using low thrust orbit

  11. Compact fluxgate magnetic full-tensor gradiometer with spherical feedback coil.

    PubMed

    Sui, Yangyi; Li, Guang; Wang, Shilong; Lin, Jun

    2014-01-01

    The magnetic tensor gradiometer, which is used for measuring the spatial derivatives of three orthogonal magnetic field components, is an important magnetic field characterization tool. Here, the construction of a magnetic full-tensor gradiometer is described, which utilizes four fluxgates arranged on a planar cross structure, and a single, triaxial, spherical feedback coil assembly. In this arrangement, one of the fluxgates is used as a reference, controlling the currents through the feedback coils. Since the fluxgates are working in the near-zero magnetic field environment, the magnetic tensor gradiometer is stable and of an improved accuracy. This design avoids the crosstalk normally caused by individual feedback coils for each fluxgate, and reduces the orthogonality and orientation errors. Moreover, the calibration parameters can be directly inferred using the spherical feedback coil. The measured gradient tensor magnitude can reach 0.52 nT/m/Hz(1/2) @ 1 Hz in unshielded laboratory conditions, while exhibiting good noise immunity. The functionality of the system is verified by locating a small, single, permanent, and dipole magnet in space. The gradiometer is compact, while employing global feedback, and therefore it is especially suitable for deployment on space-constrained moving platforms. PMID:24517792

  12. Compact fluxgate magnetic full-tensor gradiometer with spherical feedback coil

    NASA Astrophysics Data System (ADS)

    Sui, Yangyi; Li, Guang; Wang, Shilong; Lin, Jun

    2014-01-01

    The magnetic tensor gradiometer, which is used for measuring the spatial derivatives of three orthogonal magnetic field components, is an important magnetic field characterization tool. Here, the construction of a magnetic full-tensor gradiometer is described, which utilizes four fluxgates arranged on a planar cross structure, and a single, triaxial, spherical feedback coil assembly. In this arrangement, one of the fluxgates is used as a reference, controlling the currents through the feedback coils. Since the fluxgates are working in the near-zero magnetic field environment, the magnetic tensor gradiometer is stable and of an improved accuracy. This design avoids the crosstalk normally caused by individual feedback coils for each fluxgate, and reduces the orthogonality and orientation errors. Moreover, the calibration parameters can be directly inferred using the spherical feedback coil. The measured gradient tensor magnitude can reach 0.52 nT/m/Hz1/2 @ 1 Hz in unshielded laboratory conditions, while exhibiting good noise immunity. The functionality of the system is verified by locating a small, single, permanent, and dipole magnet in space. The gradiometer is compact, while employing global feedback, and therefore it is especially suitable for deployment on space-constrained moving platforms.

  13. A compact broadband ion beam focusing device based on laser-driven megagauss thermoelectric magnetic fields

    NASA Astrophysics Data System (ADS)

    Albertazzi, B.; d'Humières, E.; Lancia, L.; Dervieux, V.; Antici, P.; Böcker, J.; Bonlie, J.; Breil, J.; Cauble, B.; Chen, S. N.; Feugeas, J. L.; Nakatsutsumi, M.; Nicolaï, P.; Romagnani, L.; Shepherd, R.; Sentoku, Y.; Swantusch, M.; Tikhonchuk, V. T.; Borghesi, M.; Willi, O.; Pépin, H.; Fuchs, J.

    2015-04-01

    Ultra-intense lasers can nowadays routinely accelerate kiloampere ion beams. These unique sources of particle beams could impact many societal (e.g., proton-therapy or fuel recycling) and fundamental (e.g., neutron probing) domains. However, this requires overcoming the beam angular divergence at the source. This has been attempted, either with large-scale conventional setups or with compact plasma techniques that however have the restriction of short (<1 mm) focusing distances or a chromatic behavior. Here, we show that exploiting laser-triggered, long-lasting (>50 ps), thermoelectric multi-megagauss surface magnetic (B)-fields, compact capturing, and focusing of a diverging laser-driven multi-MeV ion beam can be achieved over a wide range of ion energies in the limit of a 5° acceptance angle.

  14. A compact broadband ion beam focusing device based on laser-driven megagauss thermoelectric magnetic fields.

    PubMed

    Albertazzi, B; d'Humières, E; Lancia, L; Dervieux, V; Antici, P; Böcker, J; Bonlie, J; Breil, J; Cauble, B; Chen, S N; Feugeas, J L; Nakatsutsumi, M; Nicolaï, P; Romagnani, L; Shepherd, R; Sentoku, Y; Swantusch, M; Tikhonchuk, V T; Borghesi, M; Willi, O; Pépin, H; Fuchs, J

    2015-04-01

    Ultra-intense lasers can nowadays routinely accelerate kiloampere ion beams. These unique sources of particle beams could impact many societal (e.g., proton-therapy or fuel recycling) and fundamental (e.g., neutron probing) domains. However, this requires overcoming the beam angular divergence at the source. This has been attempted, either with large-scale conventional setups or with compact plasma techniques that however have the restriction of short (<1 mm) focusing distances or a chromatic behavior. Here, we show that exploiting laser-triggered, long-lasting (>50 ps), thermoelectric multi-megagauss surface magnetic (B)-fields, compact capturing, and focusing of a diverging laser-driven multi-MeV ion beam can be achieved over a wide range of ion energies in the limit of a 5° acceptance angle. PMID:25933857

  15. Lightman-Eardley instabilities and accretion disk thickening. [for compact astronomical objects

    NASA Technical Reports Server (NTRS)

    Stoeger, W. R.

    1979-01-01

    After reviewing the role of Compton scattering in accretion disks around black holes, it is discussed whether Lightman-Eardley (LE) secular instabilities can trigger and maintain Pringle-Rees (PR) thermal instabilities. The radiative-transfer-equation and equation-of-state criteria for LE stability in alpha-viscosity-law disk models and dynamic viscosity criteria for more general situations is derived. On the basis of these considerations the LE instability is insufficient for inducing PR instabilities and hot thick inner regions important in accretion-disk models of compact hard X-ray sources. The density thinning due to radial velocity gradients in the accretion flow is suggested as a more likely and satisfactory mechanism.

  16. Spectroscopy of the short-hard GRB 130603B. The host galaxy and environment of a compact object merger

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, A.; Thöne, C. C.; Rowlinson, A.; García-Benito, R.; Levan, A. J.; Gorosabel, J.; Goldoni, P.; Schulze, S.; Zafar, T.; Wiersema, K.; Sánchez-Ramírez, R.; Melandri, A.; D'Avanzo, P.; Oates, S.; D'Elia, V.; De Pasquale, M.; Krühler, T.; van der Horst, A. J.; Xu, D.; Watson, D.; Piranomonte, S.; Vergani, S. D.; Milvang-Jensen, B.; Kaper, L.; Malesani, D.; Fynbo, J. P. U.; Cano, Z.; Covino, S.; Flores, H.; Greiss, S.; Hammer, F.; Hartoog, O. E.; Hellmich, S.; Heuser, C.; Hjorth, J.; Jakobsson, P.; Mottola, S.; Sparre, M.; Sollerman, J.; Tagliaferri, G.; Tanvir, N. R.; Vestergaard, M.; Wijers, R. A. M. J.

    2014-03-01

    Context. Short duration gamma-ray bursts (SGRBs) are thought to be related to the violent merger of compact objects, such as neutron stars or black holes, which makes them promising sources of gravitational waves. The detection of a "kilonova"-likesignature associated to the Swift-detected GRB 130603B has suggested that this event is the result of a compact object merger. Aims: Our knowledge on SGRB has been, until now, mostly based on the absence of supernova signatures and the analysis of the host galaxies to which they cannot always be securely associated. Further progress has been significantly hampered by the faintness and rapid fading of their optical counterparts (afterglows), which has so far precluded spectroscopy of such events. Afterglow spectroscopy is the key tool to firmly determine the distance at which the burst was produced, crucial to understand its physics, and study its local environment. Methods: Here we present the first spectra of a prototypical SGRB afterglow in which both absorption and emission features are clearly detected. Together with multi-wavelength photometry we study the host and environment of GRB 130603B. Results: From these spectra we determine the redshift of the burst to be z = 0.3565 ± 0.0002, measure rich dynamics both in absorption and emission, and a substantial line of sight extinction of AV = 0.86 ± 0.15 mag. The GRB was located at the edge of a disrupted arm of a moderately star forming galaxy with near-solar metallicity. Unlike for most long GRBs (LGRBs), NHX/AV is consistent with the Galactic ratio, indicating that the explosion site differs from those found in LGRBs. Conclusions: The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the compact object binary. Appendices are available in electronic form at http://www.aanda.org

  17. Magnetic Fabrics and Paleomagnetism of Sedimentary Rocks: Examining Effects of Compaction and Deformation

    NASA Astrophysics Data System (ADS)

    Housen, B. A.

    2006-12-01

    Sedimentary rocks provide many important records of the geometry and history of the geomagnetic field, but such records are at times compromised by the effects of depositional processes, soft-sediment deformation, compaction, and tectonic strain. One productive line of research into these effects has been to utilize the well known ability of magnetic anisotropy methods to quantitatively analyze sediment fabrics that result from these processes, and to use these data to evaluate the possibility that the remanence directions in sediments and sedimentary rocks have been altered. Two approaches to this problem will be presented. The first deals with relationships between magnetic fabric shape parameters and paleomagnetic inclination error. The second approach will be to examine the shape distributions of paleomagnetic data, and compare these to the shape distributions of AMS kmin axes from the same rocks. For the first approach, analyses of magnetic fabrics and estimates of paleomagnetic inclination error in the Shikoku Basin (ODP Site 1173) sediments indicate that both initial deposition and post-depositional compaction play important roles in shallowing of inclination. The sediments down to 344 meters depth have relatively uniform flattening values and fabric-based estimates of mean inclination errors of 3.2° for a = 5, and 5.9°° for a = 2.4. The uniform flattening factors, minor inclination errors, and uniform porosity all suggest that only the initial deposition/consolidation process, rather than burial-related compaction, has influenced the paleomagnetic inclinations of the sediments within this interval. In contrast, sediments below 344 meters depth have flattening factors and calculated inclination errors that monotonically increase with depth, with mean inclination errors of 12.1° for a = 5, and 23.3° for a = 2.4. Decrease of porosity within this same depth interval suggests that burial-related compaction within these hemipelagic sediments is the dominant

  18. Compact toroids generated by a magnetized coaxial source in the CTX experiment

    SciTech Connect

    Sherwood, A.R.; Henins, I.; Hoida, H.W.; Jarboe, T.R.; McKenna, K.F.; Linford, R.K.; Marshall, J.; Platts, D.A.

    1981-01-01

    Compact toroids containing both toroidal and poloidal magnetic field (Spheromak-type) have been generated in CTX using a magnetized coaxial plasma gun. These CTs tear loose from the gun by magnetic field line reconnection, and they are trapped in flux conservers having various geometries. In a straight cylindrical flux conserver the CTs are observed to be unstable to a gross tilting mode. Stability to the tilting mode has been demonstrated in flux conservers having an oblate trapping region; however, the geometry of the entrance region leading to the trapping volume can also have important effects. Lifetimes of about 150 ..mu..s for the CTs are typically observed. Interferometric measurements give a value of about 2 x 10/sup 14/ cm/sup -3/ for the initial plasma density. The plasma temperature measured at a single spot near the minor magnetic axis decreases to around 10 eV by the time the magnetic reconnection is complete. Spectrographic measurements and pressure probe results are in agreement with this temperature. A snipper coil has been installed to induce the CT to tear loose from the gun sooner. The use of this coil is observed to speed up the magnetic field reconnection process by about a factor of 2.

  19. Constraining compactness and magnetic field geometry of X-ray pulsars using pulse profile statistics

    SciTech Connect

    Annala, Marja; Poutanen, Juri

    2010-07-15

    We use the statistics of 131 X-ray pulsar light curves in order to constrain the neutron star compactness and the inclination of the magnetic dipole. The X-ray pulse profiles are classified according to the number of pulses seen during one period, dividing them into two classes, single- and double-peaked. The relative fraction of pulsars in these classes is compared with the probabilities predicted by a theoretical model for different types of pencil-beam patterns. Our results show that a statistic of pulse profiles does not constrain compactness of the neutron stars. In contrast to the previous claim, the data do not require the magnetic inclination to be confined in a narrow interval but instead the magnetic dipole can have arbitrary inclinations to the rotational axis. The observed fractions of different types of light curves can be explained by taking into account the X-ray detector sensitivity (i.e. detection threshold for weak pulses), which decreases the fraction of the observed double-peaked light curves.

  20. A compact and integrated immunoassay with on-chip dispensing and magnetic particle handling.

    PubMed

    Zirath, Helene; Peham, Johannes R; Schnetz, Guntram; Coll, Albert; Brandhoff, Lukas; Spittler, Andreas; Vellekoop, Michael J; Redl, Heinz

    2016-02-01

    We present a compact diagnostic platform for a rapid and sensitive detection of plasma biomarkers. The platform consists of a disposable microfluidic polymer chip, a processing device including a lens-free and cost efficient sensor system and a setup for dispersion of magnetic particles. The biomarkers of interest are quantified by magnetic bead based immunoassays with chemiluminescent readout technology. With a novel system for dispersion and manipulation of the magnetic particles in combination with chemiluminescence detection, the sensitivity of the immunoassay is improved and enables a rapid assay in a microfluidic format. In the disposable chip, extra chambers for storage and dispensing of biomarker specific reagents are integrated, which reduce the need of external dosing devices and thereby the cost of the platform is decreased. Plasma biomarkers for monitoring of sepsis could be quantified at 10 pg/mL concentrations within a total time of 30 min by the present system. This contribution is a fundamental step towards the development of an automatic and compact Point-of-Care testing device for monitoring of patients at the intensive care unit. PMID:26842948

  1. Design and system integration of the superconducting wiggler magnets for the Compact Linear Collider damping rings

    NASA Astrophysics Data System (ADS)

    Schoerling, Daniel; Antoniou, Fanouria; Bernhard, Axel; Bragin, Alexey; Karppinen, Mikko; Maccaferri, Remo; Mezentsev, Nikolay; Papaphilippou, Yannis; Peiffer, Peter; Rossmanith, Robert; Rumolo, Giovanni; Russenschuck, Stephan; Vobly, Pavel; Zolotarev, Konstantin

    2012-04-01

    To achieve high luminosity at the collision point of the Compact Linear Collider (CLIC), the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 and 4 nm before the beams enter the 1.5 TeV linear accelerators. An effective way to accomplish ultralow emittances with only small effects on the electron polarization is using damping rings operating at 2.86 GeV equipped with superconducting wiggler magnets. This paper describes a technical design concept for the CLIC damping wigglers.

  2. COMPACT OBJECT COALESCENCE RATE ESTIMATION FROM SHORT GAMMA-RAY BURST OBSERVATIONS

    SciTech Connect

    Petrillo, Carlo Enrico; Dietz, Alexander; Cavaglia, Marco

    2013-04-20

    Recent observational and theoretical results suggest that short-duration gamma-ray bursts (SGRBs) originate from the merger of compact binary systems of two neutron stars or a neutron star and a black hole. The observation of SGRBs with known redshifts allows astronomers to infer the merger rate of these systems in the local universe. We use data from the SWIFT satellite to estimate this rate to be in the range {approx}500-1500 Gpc{sup -3} yr{sup -1}. This result is consistent with earlier published results which were obtained through alternative approaches. We estimate the number of coincident observations of gravitational-wave signals with SGRBs in the advanced gravitational-wave detector era. By assuming that all SGRBs are created by neutron star-neutron star (neutron star-black hole) mergers, we estimate the expected rate of coincident observations to be in the range {approx_equal} 0.2-1 ({approx_equal} 1-3) yr{sup -1}.

  3. Optical, X-ray and gamma-ray observations of compact objects in globular clusters

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.

    1993-01-01

    In the past three years, a new era of study of globular clusters has begun with multiwavelength observations from the current generation of astronomical telescopes in space. We review the recent results obtained from our studies of compact binaries and x-ray sources in globulars with ROSAT and Hubble Space Telescope (HST) as well as our balloon-borne hard x-ray telescope EXITE (Energetic X-ray Imaging Telescope Experiment) and ground-based observations (CTIO). With ROSAT, we have obtained the most sensitive high resolution soft x-ray images of clusters which show multiple low luminosity sources in cluster cores that are likely indicative of the long-sought population of cataclysmic variables (CVs). We have obtained deep H-alpha images of two clusters with HST and found CV candiates for 3 of the ROSAT sources in the core of NGC 6397. New CTIO imaging and spectroscopy of two 'dim source' fields in omega-Cen are also described. With EXITE we carried out the first hard x-ray imaging observations of the cluster 47 Tuc; such studies can ultimately limit the populations of millisecond pulsars and pulsar emission mechanisms. A long ROSAT exposure on 47 Tuc also shows probable cluster diffuse emission, possibly due to hot gas from ablating millisecond pulsars. Multiwavelength studies of globular clusters may provide new constraints on problems as diverse as the origin of CVs and low mass X-ray binaries (LMXBs) and the origin of hot gas in globulars.

  4. Compact object mergers: observations of supermassive binary black holes and stellar tidal disruption events

    NASA Astrophysics Data System (ADS)

    Komossa, S.; Zensus, J. A.

    2016-02-01

    The capture and disruption of stars by supermassive black holes (SMBHs), and the formation and coalescence of binaries, are inevitable consequences of the presence of SMBHs at the cores of galaxies. Pairs of active galactic nuclei (AGN) and binary SMBHs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. In the early and advanced stages of galaxy merging, observations of the triggering of accretion onto one or both BHs inform us about feedback processes and BH growth. Identification of the compact binary SMBHs at parsec and sub-parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the ``final parsec''. Coalescing binary SMBHs are among the most powerful sources of gravitational waves (GWs) in the universe. Stellar tidal disruption events (TDEs) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the SMBH. About 30 events have been identified by multi-wavelength observations by now, and they will be detected in the thousands in future ground-based or space-based transient surveys. The study of TDEs provides us with a variety of new astrophysical tools and applications, related to fundamental physics or astrophysics. Here, we provide a review of the current status of observations of SMBH pairs and binaries, and TDEs, and discuss astrophysical implications.

  5. A Permanent-Magnet Microwave Ion Source for a Compact High-Yield Neutron Generator

    SciTech Connect

    Waldmann, Ole; Ludewigt, Bernhard

    2010-10-11

    We present recent work on the development of a microwave ion source that will be used in a high-yield compact neutron generator for active interrogation applications. The sealed tube generator will be capable of producing high neutron yields, 5x1011 n/s for D-T and ~;;1x1010 n/s for D-D reactions, while remaining transportable. We constructed a microwave ion source (2.45 GHz) with permanent magnets to provide the magnetic field strength of 87.5 mT necessary for satisfying the electron cyclotron resonance (ECR) condition. Microwave ion sources can produce high extracted beam currents at the low gas pressures required for sealed tube operation and at lower power levels than previously used RF-driven ion sources. A 100 mA deuterium/tritium beam will be extracted through a large slit (60x6 mm2) to spread the beam power over a larger target area. This paper describes the design of the permanent-magnet microwave ion source and discusses the impact of the magnetic field design on the source performance. The required equivalent proton beam current density of 40 mA/cm2 was extracted at a moderate microwave power of 400 W with an optimized magnetic field.

  6. A compact highly efficient and low hemolytic centrifugal blood pump with a magnetically levitated impeller.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2006-03-01

    A magnetically levitated (maglev) centrifugal blood pump (CBP), intended for use as a ventricular assist device, needs to be highly durable and reliable for long-term use without any mechanical failure. Furthermore, maglev CBPs should be small enough to be implanted into patients of various size and weight. We have developed a compact maglev CBP employing a two-degree-of-freedom controlled magnetic bearing, with a magnetically suspended impeller directly driven by an internal brushless direct current (DC) motor. The magnetic bearing actively controls the radial motion of the impeller and passively supports axial and angular motions using a permanent magnet embedded in the impeller. The overall dimensions of the maglev CBP are 65 mm in diameter and 40 mm in height. The total power consumption and pump efficiency for pumping 6 L/min against a head pressure of 105 mm Hg were 6.5 W and 21%, respectively. To evaluate the characteristics of the maglev CBP when subjected to a disturbance, excitation of the base, simulating the movement of the patient in various directions, and the sudden interception of the outlet tube connected with the pump in a mock circulatory loop, simulating an unexpected kink and emergent clamp during a heart surgery, were tested by monitoring the five-degree-of-freedom motion of the impeller. Furthermore, the hemolytic characteristics of the maglev CBP were compared with those of the Medtronic Biomedicus BPX-80, which demonstrated the superiority of the maglev CBP. PMID:16480390

  7. Stable Levitation and Alignment of Compact Objects by Casimir Spring Forces

    SciTech Connect

    Rahi, Sahand Jamal; Zaheer, Saad

    2010-02-19

    We investigate a stable Casimir force configuration consisting of an object contained inside a spherical or spheroidal cavity filled with a dielectric medium. The spring constant for displacements from the center of the cavity and the dependence of the energy on the relative orientations of the inner object and the cavity walls are computed. We find that the stability of the force equilibrium--unlike the direction of the torque--can be predicted based on the sign of the force between two slabs of the same material.

  8. Ideal magnetohydrodynamic simulations of low beta compact toroid injection into a hot strongly magnetized plasma

    SciTech Connect

    Liu, Wei; Hsu, Scott; Li, Hui

    2009-01-01

    We present results from three-dimensional ideal magnetohydrodynamic simulations of low {beta} compact toroid (CT) injection into a hot strongly magnetized plasma, with the aim of providing insight into CT fueling of a tokamak with parameters relevant for ITER (International Thermonuclear Experimental Reactor). A regime is identified in terms of CT injection speed and CT-to-background magnetic field ratio that appears promising for precise core fueling. Shock-dominated regimes, which are probably unfavorable for tokamak fueling, are also identified. The CT penetration depth is proportional to the CT injection speed and density. The entire CT evolution can be divided into three stages: (1) initial penetration, (2) compression in the direction of propagation and reconnection, and (3) coming to rest and spreading in the direction perpendicular to injection. Tilting of the CT is not observed due to the fast transit time of the CT across the background plasma.

  9. Compact 14.5 GHz all-permanent magnet ECRIS for experiments with slow multicharged ions

    NASA Astrophysics Data System (ADS)

    Galutschek, E.; Trassl, R.; Salzborn, E.; Aumayr, F.; Winter, Hp

    2007-03-01

    A compact 14.5 GHz electron cyclotron resonance ion source (ECRIS) for production of multiply charged ions (MCI) with a plasma-confining magnetic field generated by permanent magnets has been constructed. Microwave power with frequency between 12.75 and 14.5 GHz is transmitted from ground potential via an insulating window into the watercooled plasma chamber fitted with an aluminium liner. The HF coupling system serves as biased electrode. Operation in the gas-mixing mode is achieved with two remotely controlled gas inlet valves. The triode ion extraction system has been optimized for low acceleration voltages between 1 and 10 kV. The ECRIS is fully computer-controlled and can be remotely operated via Ethernet. Finally, we refer to recent experimental work on collisions of slow MCI generated by the new ECRIS with neutral gas particles and surfaces.

  10. Conducting object in the presence of a variable magnetic field

    NASA Astrophysics Data System (ADS)

    Savchenko, A. O.; Savchenko, O. Ya.

    2015-07-01

    A numerical method is proposed to determine vector potential and gradient of scalar potential inside a conductor in the presence of a magnetic field that exhibits harmonic variations with time. The problem is reduced to the solution of the Helmholtz equation in a conducting object under the condition that the normal component of the right-hand side of equation on the conducting surface is zero. An iterative procedure is proposed for the solution of the original problem. First, the surface charge distribution that satisfies the boundary condition for the vector potential on the conducting surface is found, and, then, the next approximation for the vector potential is obtained with the aid of the Poisson equation. The method is illustrated using numerical experiments.

  11. Segmentation, modeling and classification of the compact objects in a pile

    NASA Technical Reports Server (NTRS)

    Gupta, Alok; Funka-Lea, Gareth; Wohn, Kwangyoen

    1990-01-01

    The problem of interpreting dense range images obtained from the scene of a heap of man-made objects is discussed. A range image interpretation system consisting of segmentation, modeling, verification, and classification procedures is described. First, the range image is segmented into regions and reasoning is done about the physical support of these regions. Second, for each region several possible three-dimensional interpretations are made based on various scenarios of the objects physical support. Finally each interpretation is tested against the data for its consistency. The superquadric model is selected as the three-dimensional shape descriptor, plus tapering deformations along the major axis. Experimental results obtained from some complex range images of mail pieces are reported to demonstrate the soundness and the robustness of our approach.

  12. Magnetic Field Line Tracing Calculations for Conceptual PFC Design in the National Compact Stellarator Experiment

    SciTech Connect

    Maingi, R; Kaiser, T; Hill, D N; Lyon, J F; Monticello, D; Zarnstorff, M C

    2006-06-12

    The National Compact Stellarator Experiment (NCSX) is a three-field period compact stellarator presently in the construction phase at Princeton, NJ. The design parameters of the device are major radius R=1.4m, average minor radius = 0.32m, 1.2 {le} toroidal field (B{sub t}) {le} 1.7 T, and auxiliary input power up to 12 MW with neutral beams and radio-frequency heating. The NCSX average aspect ratio of 4.4 lies well below present stellarator experiments and designs, enabling the investigation of high {beta} physics in a compact stellarator geometry. Also the NCSX design choice for a quasi-axisymmetric configuration aims toward the achievement of tokamak-like transport. In this paper, we report on the magnetic field line tracing calculations used to evaluate conceptual plasma facing component (PFC) designs. In contrast to tokamaks, axisymmetric target plates are not required to intercept the majority of the heat flux in stellarators, owing to the nature of the 3-D magnetic field footprint. The divertor plate design investigated in this study covers approximately one half of the toroidal extent in each period. Typical Poincare plots in Figure 1 illustrate the plasma cross-section at several toroidal angles for a computed NCSX high-beta equilibrium. The plates used for these calculations are centered in each period about the elongated cross-section shown in Figure 1a, extending to +/- {pi}/6 in each direction. Two methods for tracing the edge field line topology were used in this study. The first entails use of the VMEC/MFBE-2001 packages, whereas the second entails use of the PIES code with a post-processor by Michael Drevlak; the same field line integration routine was used to evaluate the equilibria for this comparison. Both inputs were generated based on the {beta}=4%, =iota=0.5 equilibrium computed from the final NCSX coil set. We first compare these two methods for a specific plate geometry, and conclude with a comparison of the strike characteristics

  13. Magnetic Field Line Topology of the Scrape-Off Layer in the Compact Stellarator NCSX

    NASA Astrophysics Data System (ADS)

    Grossman, Arthur; Mioduszewski, Peter; Fenstermacher, Max; Koniges, Alice; Rognlien, Tom

    2001-10-01

    The magnetic topology of the plasma boundary of the proposed compact stellarator NCSX is investigated using the MFBE[1] and VMEC2000[2] codes. The VMEC code provides a free boundary equilibrium and the magnetics from external coils and bootstrap plasma currents inside the last closed magnetic surface (LCMS). The MFBE code uses these results to calculate the magnetic fields of these finite beta equilibria outside the LCMS in a form suitable for line tracing. The Poincaré plots of field lines started outside the LCMS indicate preservation of initial radial ordering of field lines up to intersections with vacuum vessel and plasma facing components. A large flux expansion of field lines is observed between the midplane and tips of the banana shaped cross-section, due to the presence of a nearby poloidal field null used to create the banana shape. TRIM coils used to heal islands just within the LCMS appear to reduce stochasticity just outside the LCMS as well as enhance an island structure outside the LCMS. Field lines are observed to move in and out radially as they are followed toroidally. Power and particle control design based on these observations include the limiting structure geometry and baffles designed to intersect islands outside the LCMS. [1] E.Strumberger, Nuclear Fusion 37 1997 19. [2] S.Hirshman, Comp. Phys. Commun. 43 1986 143.

  14. Compact Objects In Binary Systems: Formation and Evolution of X-ray Binaries and Tides in Double White Dwarfs

    NASA Astrophysics Data System (ADS)

    Valsecchi, Francesca

    Binary star systems hosting black holes, neutron stars, and white dwarfs are unique laboratories for investigating both extreme physical conditions, and stellar and binary evolution. Black holes and neutron stars are observed in X-ray binaries, where mass accretion from a stellar companion renders them X-ray bright. Although instruments like Chandra have revolutionized the field of X-ray binaries, our theoretical understanding of their origin and formation lags behind. Progress can be made by unravelling the evolutionary history of observed systems. As part of my thesis work, I have developed an analysis method that uses detailed stellar models and all the observational constraints of a system to reconstruct its evolutionary path. This analysis models the orbital evolution from compact-object formation to the present time, the binary orbital dynamics due to explosive mass loss and a possible kick at core collapse, and the evolution from the progenitor's Zero Age Main Sequence to compact-object formation. This method led to a theoretical model for M33 X-7, one of the most massive X-ray binaries known and originally marked as an evolutionary challenge. Compact objects are also expected gravitational wave (GW) sources. In particular, double white dwarfs are both guaranteed GW sources and observed electromagnetically. Although known systems show evidence of tidal deformation and a successful GW astronomy requires realistic models of the sources, detached double white dwarfs are generally approximated to point masses. For the first time, I used realistic models to study tidally-driven periastron precession in eccentric binaries. I demonstrated that its imprint on the GW signal yields constrains on the components' masses and that the source would be misclassified if tides are neglected. Beyond this adiabatic precession, tidal dissipation creates a sink of orbital angular momentum. Its efficiency is strongest when tides are dynamic and excite the components' free

  15. Air Conditioning with Magnetic Refrigeration : An Efficient, Green Compact Cooling System Using Magnetic Refrigeration

    SciTech Connect

    2010-09-01

    BEETIT Project: Astronautics is developing an air conditioning system that relies on magnetic fields. Typical air conditioners use vapor compression to cool air. Vapor compression uses a liquid refrigerant to circulate within the air conditioner, absorb the heat, and pump the heat out into the external environment. Astronautics’ design uses a novel property of certain materials, called “magnetocaloric materials”, to achieve the same result as liquid refrigerants. These magnetocaloric materials essentially heat up when placed within a magnetic field and cool down when removed, effectively pumping heat out from a cooler to warmer environment. In addition, magnetic refrigeration uses no ozone-depleting gases and is safer to use than conventional air conditioners which are prone to leaks.

  16. A compact theory of magnetic nerve stimulation: predicting how to aim

    PubMed Central

    2014-01-01

    Background A compact theory that predicts quantitatively when and where magnetic neurostimulation will occur is needed as a guide to therapy, ideally providing a single equation that defines the target volume of tissue excited by single or dual coils. Methods A first-principles analysis of magnetic stimulation incorporating a simplified description of electromagnetic fields and a simplified cable theory of the axon yields a mathematical synthesis predicting how to aim. Results Nerve stimulation produced by a single circular coil having one or more closely packed turns occurs in donut shaped volume of tissue beneath the coil. Axons spanning several millimeters are the sites of magnetic stimulation. The sites of maximal transmembrane depolarization in nerve fibers correspond to points where the axons enter or exit this volume of magnetically induced voltage and current. The axonal membrane at one end is depolarized locally during the rising phase of current in the coil. The axonal membrane at the opposite end is depolarized locally during the falling phase of current in the coil. Penetration depths of several centimeters from the skin surface or approximately one to two coil radii are practical. With two coils placed in a figure-of-eight configuration the separate clockwise and counterclockwise currents generate magnetic fields that add, producing maximal stimulation of a spindle shaped volume, centered at a depth of one-third to one-half coil radius from the body surface. Conclusions This condensed synthesis of electromagnetic theory and cable theories of axon physiology provides a partial solution to the targeting problem in peripheral and in transcranial magnetic stimulation. PMID:24885299

  17. Towards a formalism for mapping the spacetimes of massive compact objects: Bumpy black holes and their orbits

    NASA Astrophysics Data System (ADS)

    Collins, Nathan A.; Hughes, Scott A.

    2004-06-01

    Astronomical observations have established that extremely compact, massive objects are common in the Universe. It is generally accepted that these objects are, in all likelihood, black holes. As observational technology has improved, it has become possible to test this hypothesis in ever greater detail. In particular, it is or will be possible to measure the properties of orbits deep in the strong field of a black hole candidate (using x-ray timing or future gravitational-wave measurements) and to test whether they have the characteristics of black hole orbits in general relativity. Past work has shown that, in principle, such measurements can be used to map the spacetime of a massive compact object, testing in particular whether the object’s multipolar structure satisfies the rather strict constraints imposed by the black hole hypothesis. Performing such a test in practice requires that we be able to compare against objects with the “wrong” multipole structure. In this paper, we present tools for constructing the spacetimes of bumpy black holes: objects that are almost black holes, but that have some multipoles with the wrong value. In this first analysis, we focus on objects with no angular momentum. Generalization to bumpy Kerr black holes should be straightforward, albeit labor intensive. Our construction has two particularly desirable properties. First, the spacetimes which we present are good deep into the strong field of the object—we do not use a “large r” expansion (except to make contact with weak field intuition). Second, our spacetimes reduce to the exact black hole spacetimes of general relativity in a natural way, by dialing the “bumpiness” of the black hole to zero. We propose that bumpy black holes can be used as the foundation for a null experiment: if black hole candidates are indeed the black holes of general relativity, their bumpiness should be zero. By comparing the properties of orbits in a bumpy spacetime with those measured

  18. Discovery of new objects in the Orion nebula on HST images - Shocks, compact sources, and protoplanetary disks

    NASA Technical Reports Server (NTRS)

    O'Dell, C. R.; Wen, Zheng; Hu, Xihai

    1993-01-01

    We have reduced and analyzed a set of narrow-band HST images of a portion of M42 south of the Trapezium. Many new emission-line sources were found, some quite long but so narrow that they are not seen on ground-based images. These include thin shells which are high-ionization shocks. The structure around Orion HH 3 is resolved into multiple components. Slit spectroscopy data establish the high expansion velocities of all these regions. The other objects seen are compact sources. Although some had been detected in VLA surveys and several had been seen from the ground optically, the new images show previously undetected structure and clearly establish that most are protoplanetary disks, which are neutral disks surrounding low-mass pre-main-sequence stars and are ionized from the outside by Theta sup 1 C and Theta sup 2 A Ori.

  19. A RAY-TRACING ALGORITHM FOR SPINNING COMPACT OBJECT SPACETIMES WITH ARBITRARY QUADRUPOLE MOMENTS. I. QUASI-KERR BLACK HOLES

    SciTech Connect

    Psaltis, Dimitrios; Johannsen, Tim

    2012-01-20

    We describe a new numerical algorithm for ray tracing in the external spacetimes of spinning compact objects characterized by arbitrary quadrupole moments. Such spacetimes describe non-Kerr vacuum solutions that can be used to test the no-hair theorem in conjunction with observations of accreting black holes. They are also appropriate for neutron stars with spin frequencies in the {approx_equal} 300-600 Hz range, which are typical of the bursting sources in low-mass X-ray binaries. We use our algorithm to show that allowing for the quadrupole moment of the spacetime to take arbitrary values leads to observable effects in the profiles of relativistic broadened fluorescent iron lines from geometrically thin accretion disks.

  20. AN ULTRA-LOW-MASS AND SMALL-RADIUS COMPACT OBJECT IN 4U 1746-37?

    SciTech Connect

    Li, Zhaosheng; Qu, Zhijie; Guo, Yanjun; Xu, Renxin; Chen, Li; Qu, Jinlu

    2015-01-01

    Photospheric radius expansion (PRE) bursts have already been used to constrain the masses and radii of neutron stars. RXTE observed three PRE bursts in 4U 1746-37, all with low touchdown fluxes. We discuss here the possibility of a low-mass neutron star in 4U 1746-37 because the Eddington luminosity depends on stellar mass. With typical values of hydrogen mass fraction and color correction factor, a Monte Carlo simulation was applied to constrain the mass and radius of a neutron star in 4U 1746-37. 4U 1746-37 has a high inclination angle. Two geometric effects, the reflection of the far-side accretion disk and the obscuration of the near-side accretion disk, have also been included in the mass and radius constraints of 4U 1746-37. If the reflection of the far-side accretion disk is accounted for, a low-mass compact object (mass of 0.41 ± 0.14 M {sub ☉} and radius of 8.73 ± 1.54 km at 68% confidence) exists in 4U 1746-37. If another effect operated, 4U 1746-37 may contain an ultra-low-mass and small-radius object (M = 0.21 ± 0.06 M {sub ☉}, R = 6.26 ± 0.99 km at 68% confidence). Combining all possibilities, the mass of 4U 1746-37 is 0.41{sub −0.30}{sup +0.70} M{sub ⊙} at 99.7% confidence. For such low-mass neutron stars, it could be reproduced by a self-bound compact star, i.e., a quark star or quark-cluster star.

  1. DIRECT IMAGING OF A COMPACT MOLECULAR OUTFLOW FROM A VERY LOW LUMINOSITY OBJECT: L1521F-IRS

    SciTech Connect

    Takahashi, Satoko; Ohashi, Nagayoshi; Bourke, Tyler L.

    2013-09-01

    Studying the physical conditions of very low luminosity objects (VeLLOs; L{sub bol} < 0.1 L{sub Sun }) is important for understanding the earliest evolutionary stage of protostars and brown dwarfs. We report interferometric observations of the VeLLO L1521F-IRS, in {sup 12}CO (2-1) line emission and the 1.3 mm continuum emission, using the Submillimeter Array. With the {sup 12}CO (2-1) high-resolution observations, we have spatially resolved a compact but poorly collimated molecular outflow associated with L1521F-IRS for the first time. The blueshifted and redshifted lobes are aligned along the east and west side of L1521F-IRS with a lobe size of Almost-Equal-To 1000 AU. The estimated outflow mass, maximum outflow velocity, and outflow force are (9.0-80) Multiplication-Sign 10{sup -4} M{sub Sun }, 7.2 km s{sup -1}, and (7.4-66) Multiplication-Sign 10{sup -7} M{sub Sun} km s{sup -1} yr{sup -1}, respectively. The estimated outflow parameters such as size, mass, and momentum rate are similar to values derived for other VeLLOs, and are located at the lower end of values compared to previously studied outflows associated with low- to high-mass star-forming regions. Low-velocity less collimated (1.5 km s{sup -1}/1200 AU) and higher-velocity compact (4.0 km s{sup -1}/920 AU) outflow components are suggested by the data. These velocity structures are not consistent with those expected in the jet-driven or wind-driven outflow models, perhaps suggesting a remnant outflow from the first hydrostatic core as well as an undeveloped outflow from the protostar. Detection of an infrared source and compact millimeter continuum emission suggests the presence of the protostar, while its low bolometric luminosity (0.034-0.07 L{sub Sun }) and small outflow suggests that L1521F is in the earliest protostellar stage (<10{sup 4} yr) and contains a substellar mass object. The bolometric (or internal) luminosity of L1521F-IRS suggests that the current mass accretion rate is an order of

  2. TRANSITS AND LENSING BY COMPACT OBJECTS IN THE KEPLER FIELD: DISRUPTED STARS ORBITING BLUE STRAGGLERS

    SciTech Connect

    Di Stefano, R.

    2011-05-15

    Kepler's first major discoveries are two hot (T > 10,000 K) small-radius objects orbiting stars in its field. A viable hypothesis is that these are the cores of stars that have each been eroded or disrupted by a companion star. The companion, which is the star monitored today, is likely to have gained mass from its now-defunct partner and can be considered to be a blue straggler. KOI-81 is almost certainly the product of stable mass transfer; KOI-74 may be as well, or it may be the first clear example of a blue straggler created through three-body interactions. We show that mass-transfer binaries are common enough that Kepler should discover {approx}1000 white dwarfs orbiting main-sequence stars. Most of these, like KOI-74 and KOI-81, will be discovered through transits, but many will be discovered through a combination of gravitational lensing and transits, while lensing will dominate for a subset. In fact, some events caused by white dwarfs will have the appearance of 'anti-transits' - i.e., short-lived enhancements in the amount of light received from the monitored star. Lensing and other mass-measurement methods provide a way to distinguish white dwarf binaries from planetary systems. This is important for the success of Kepler's primary mission, in light of the fact that white dwarf radii are similar to the radii of terrestrial planets, and that some white dwarfs will have orbital periods that place them in the habitable zones of their stellar companions. By identifying transiting and/or lensing white dwarfs, Kepler will conduct pioneering studies of white dwarfs and of the end states of mass transfer. It may also identify orbiting neutron stars or black holes. The calculations inspired by the discovery of KOI-74 and KOI-81 have implications for ground-based wide-field surveys as well as for future space-based surveys.

  3. Object-Oriented Fast Multipole Simulation: Magnetic Colloids

    NASA Astrophysics Data System (ADS)

    Visscher, Pieter; Günal, Yüksel

    1997-08-01

    In simulating a system of N particles, if the interaction is long-ranged all pair interactions must be calculated, requiring CPU time of order N^2. Recently-developed ``fast multipole'' methods (FMM) can reduce this time to order N, at the cost of considerable programming complexity. We have developed an object-oriented approach which uses similar ideas but is conceptually much simpler. The system is represented by a hierarchical tree whose root is the entire system and whose lowest nodes are the particles. The entire calculation of the particle interactions consists of a single call to a recursive function CalculateInteractions(A,B) with A=B=root, which uses a simple opening-angle criterion to choose between multipole expansion and calling itself (subdividing A and B.) The resulting algorithm is essentially equivalent to the FMM, but the choice of when to subdivide (which is laboriously hard-wired in FMM) is made automatically. We will discuss the implementation of periodic BCs and the application of the method to continuum systems (cylindrical magnetic particles).

  4. Experimental investigation of plasma relaxation using a compact coaxial magnetized plasma gun in a background plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott; University of New Mexico Collaboration; Los Alamos National Laboratory Collaboration

    2013-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation in a low density background plasma. Experiments are being conducted in the linear HelCat device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes within the intergalactic medium. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5-10 kV and ~100 kA. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities ~1.2Cs and densities ~1020 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  5. Field Performance of an Optimized Stack of YBCO Square "Annuli" for a Compact NMR Magnet.

    PubMed

    Hahn, Seungyong; Voccio, John; Bermond, Stéphane; Park, Dong-Keun; Bascuñán, Juan; Kim, Seok-Beom; Masaru, Tomita; Iwasa, Yukikazu

    2011-06-01

    The spatial field homogeneity and time stability of a trapped field generated by a stack of YBCO square plates with a center hole (square "annuli") was investigated. By optimizing stacking of magnetized square annuli, we aim to construct a compact NMR magnet. The stacked magnet consists of 750 thin YBCO plates, each 40-mm square and 80- μm thick with a 25-mm bore, and has a Ø10 mm room-temperature access for NMR measurement. To improve spatial field homogeneity of the 750-plate stack (YP750) a three-step optimization was performed: 1) statistical selection of best plates from supply plates; 2) field homogeneity measurement of multi-plate modules; and 3) optimal assembly of the modules to maximize field homogeneity. In this paper, we present analytical and experimental results of field homogeneity and temporal stability at 77 K, performed on YP750 and those of a hybrid stack, YPB750, in which two YBCO bulk annuli, each Ø46 mm and 16-mm thick with a 25-mm bore, are added to YP750, one at the top and the other at the bottom. PMID:22081753

  6. The characterization of human compact bone structure changes by low-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Ni, Qingwen; Derwin King, J.; Wang, Xiaodu

    2004-01-01

    A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for characterizing the porosity and (effective) pore size distribution in vitro in human compact bone. The technique involves spin spin relaxation measurement and inversion spin spin relaxation spectral analysis methods. The spin spin relaxation decay curve is converted into a T2 distribution spectrum by a sum of single exponential decays. The advantages of using low-field NMR for the spin spin relaxation technique are illustrated. The results obtained from NMR methodology are compared with the results obtained from currently available but destructive histomorphometry and mercury porosimetry methods. The NMR porosities correlate well with the results obtained from the histomorphometry measurements of eight samples from donors of ages 21 89 years. The pore size distributions from T2 relaxation measurements are similar to the distributions obtained from the mercury porosimetry and histomorphometry measurements. This indicates that the age-related porosity and pore size changes in human compact bone can be detected using the low-field NMR technique.

  7. Proposal of a novel compact P-band magnetically insulated transmission line oscillator with inclined vanes

    SciTech Connect

    Zhang, Xiaoping Dang, Fangchao; Li, Yangmei; Jin, Zhenxing

    2015-06-15

    In this paper, we present a novel compact P-band magnetically insulated transmission line oscillator (MILO) with specially inclined slow-wave-structure (SWS) vanes to decrease its total dimension and weight. The dispersion characteristics of the inclined SWS are investigated in detail and made comparisons with that of the traditional straight SWS. The results show that the inclined SWS is more advantageous in operating on a steady frequency in a wide voltage range and has a better asymmetric mode segregation and a relatively large band-gap between the TM{sub 00} and TM{sub 01} modes which are in favor of avoiding the asymmetric and transverse mode competition. Besides, the transverse dimension of the proposed novel inclined SWS with the same operation frequency is decreased by about 50%, and correspondingly the device volume shrinks remarkably to its 0.35 times. In particle-in-cell simulation, the electron bunching spokes are obviously formed in the inclined SWS, and a P-band high-power microwave with a power of 5.8 GW, frequency of 645 MHz, and efficiency of 17.2% is generated by the proposed device, which indicates the feasibility of the compact design with the inclined vanes at the P-band.

  8. Development of advanced compact railguns for injection of hypervelocity hydrogen pellets into magnetic fusion plasmas

    SciTech Connect

    Tompkins, M.W.; Anderson, M.A.; Kim, K.; Feng, Q.; Zhang, J.; King, T.L.

    1995-12-31

    The authors have designed, fabricated, and tested a number of compact railguns utilizing a variety of gun geometries, augmentation schemes, and state-of-the-art rail and insulator materials in order to develop an injector that can accelerate pellets of hydrogen isotopes to very high velocities ({approximately}10 km/s) continuously and at high repetition rates for refueling magnetically confined fusion plasmas. These advanced guns are designed to achieve two goals: to minimize or eliminate gunwall erosion and to produce the maximum possible pellet acceleration. These closely related goals assure long gun lifetimes. Using an advanced transaugmented compact gun with an acceleration length of only 45-cm, they have recently achieved hydrogen pellet velocities as high as 2.2 km/s with a time-averaged pellet acceleration of 4.7 {times} 10{sup 6} m/s{sup 2} at a modest rail current of 10 kA. This paper includes a brief overview of the railgun control and diagnostic systems and discusses recent results of the railgun experiments using both plexiglass and cryogenic hydrogen pellets.

  9. A comprehensive analysis of the magnetic standard star HD 94660: Host of a massive compact companion?

    NASA Astrophysics Data System (ADS)

    Bailey, J. D.; Grunhut, J.; Landstreet, J. D.

    2015-03-01

    Aims: Detailed information about the magnetic geometry, atmospheric abundances and radial velocity variations has been obtained for the magnetic standard star HD 94660 based on high-dispersion spectroscopic and spectropolarimetric observations from the UVES, HARPSpol and ESPaDOnS instruments. Methods: We perform a detailed chemical abundance analysis using the spectrum synthesis code ZEEMAN for a total of 17 elements. Using both line-of-sight and surface magnetic field measurements, we derive a simple magnetic field model that consists of dipole, quadrupole and octupole components. Results: The observed magnetic field variations of HD 94660 are complex and suggest an inhomogeneous distribution of chemical elements over the stellar surface. This inhomogeneity is not reflected in the abundance analysis, from which all available spectra are modelled, but only a mean abundance is reported for each element. The derived abundances are mostly non-solar, with striking overabundances of Fe-peak and rare-earth elements. Of note are the clear signatures of vertical chemical stratification throughout the stellar atmosphere, most notably for the Fe-peak elements. We also report on the detection of radial velocity variations with a total range of 35 km s-1 in the spectra of HD 94660. A preliminary analysis shows the most likely period of these variations to be of order 840 d and, based on the derived orbital parameters of this star, suggests the first detection of a massive compact companion for a main sequence magnetic star. Conclusions: HD 94660 exhibits interestingly complex magnetic field variations and remarkable radial velocity variations. Long term monitoring is necessary to provide further constraints on the nature of these radial velocity variations. Detection of a companion will help establish the role of binarity in the origin of magnetism in stars with radiative envelopes. Based in part on our own observations made with the European Southern Observatory (ESO

  10. Monochromatic short pulse laser produced ion beam using a compact passive magnetic device

    SciTech Connect

    Chen, S. N.; Gauthier, M.; Higginson, D. P.; Dorard, S.; Marquès, J.-R.; Fuchs, J.; Mangia, F.; Atzeni, S.; Riquier, R.; CEA, DAM, DIF, F-91297 Arpajon

    2014-04-15

    High-intensity laser accelerated protons and ions are emerging sources with complementary characteristics to those of conventional sources, namely high charge, high current, and short bunch duration, and therefore can be useful for dedicated applications. However, these beams exhibit a broadband energy spectrum when, for some experiments, monoenergetic beams are required. We present here an adaptation of conventional chicane devices in a compact form (10 cm × 20 cm) which enables selection of a specific energy interval from the broadband spectrum. This is achieved by employing magnetic fields to bend the trajectory of the laser produced proton beam through two slits in order to select the minimum and maximum beam energy. The device enables a production of a high current, short duration source with a reproducible output spectrum from short pulse laser produced charged particle beams.

  11. Compact transverse-magnetic-pass polarizer based on one-dimensional photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Kim, Dong Wook; Lee, Moon Hyeok; Kim, Yudeuk; Kim, Kyong Hon

    2016-03-01

    We propose a compactly integrated transverse-magnetic (TM)-pass polarizer based on rectangular-shape onedimensional photonic-crystal silicon waveguide with an extremely high polarization extinction ratio of >30 dB and low insertion loss (~1 dB) over a broad wavelength range of 210 nm from 1,460 nm to 1,670 nm. The polarizer has been numerically simulated using three-dimensional finite-difference time-domain (3D FDTD) method. The optimum length of the proposed TM-pass polarizer is about 4 μm. At the 1,550 nm wavelength, the simulated polarization extinction ratio of the polarizer is 36 dB, and its corresponding insertion loss is about 1 dB.

  12. A Compact Disk Type Plasma Propulsion System with Modulated Magnetic Field for Nanoscale Space Vehicles

    NASA Astrophysics Data System (ADS)

    Fukuda, Takeshi; Ueda, Satoshi; Ohnishi, Yukihiro; Inomoto, Michiaki

    2008-12-01

    A compact 5 mm disk type plasma thruster simply composed of only a set of antenna windings and bias field coil which produces significant thrust of 0.74 mN with rotating magnetic field has been proposed and successfully developed for future applications to low altitude nanosatellites. The key technology issue is that the rotating speed is set above the ion plasma frequency but far below the electron plasma frequency, in order to produce the electron drag current and axial electric field as a consequence of the interaction with the bias field. The formation of axial electric field was confirmed and the produced plasma density was >6×1018 m-3, whereas the power consumption is 500 W in the inductively coupled mode of operation. The anticipated thrust density and specific thrust could potentially be extended to 7.64 Nm-2 and 850 s, respectively, which is comparable to conventional Hall effect thrusters.

  13. Monochromatic short pulse laser produced ion beam using a compact passive magnetic device.

    PubMed

    Chen, S N; Gauthier, M; Higginson, D P; Dorard, S; Mangia, F; Riquier, R; Atzeni, S; Marquès, J-R; Fuchs, J

    2014-04-01

    High-intensity laser accelerated protons and ions are emerging sources with complementary characteristics to those of conventional sources, namely high charge, high current, and short bunch duration, and therefore can be useful for dedicated applications. However, these beams exhibit a broadband energy spectrum when, for some experiments, monoenergetic beams are required. We present here an adaptation of conventional chicane devices in a compact form (10 cm × 20 cm) which enables selection of a specific energy interval from the broadband spectrum. This is achieved by employing magnetic fields to bend the trajectory of the laser produced proton beam through two slits in order to select the minimum and maximum beam energy. The device enables a production of a high current, short duration source with a reproducible output spectrum from short pulse laser produced charged particle beams. PMID:24784604

  14. A simple compact UHV and high magnetic field compatible inertial nanopositioner

    NASA Astrophysics Data System (ADS)

    Pang, Zongqiang; Li, Xiang; Xu, Lei; Rong, Zhou; Liu, Ruilan

    2015-01-01

    We present a novel simple piezoelectric nanopositioner which just has one piezoelectric scanner tube (PST) and one driving signal, using two short quartz rods and one BeCu spring which form a triangle to press the central shaft and can promise the nanopositioner's rigidity. Applying two pulse inverted voltage signals on the PST's outer and inner electrodes, respectively, according to the principle of piezoelectricity, the PST will elongate or contract suddenly while the central shaft will keep stationary for its inertance, so the central shaft will be sliding a distance relative to quartz rods and spring, and then withdraw the pulse voltages slowly, the central shaft will move upward or downward one step. The heavier of the central shaft, the better moving stability, so the nanopositioner has high output force. Due to its compactness and mechanical stability, it can be easily implanted into some extreme conditions, such as ultrahigh vacuum, ultralow temperature, and high magnetic field.

  15. A Compact Disk Type Plasma Propulsion System with Modulated Magnetic Field for Nanoscale Space Vehicles

    SciTech Connect

    Fukuda, Takeshi; Ueda, Satoshi; Ohnishi, Yukihiro; Inomoto, Michiaki

    2008-12-31

    A compact 5 mm disk type plasma thruster simply composed of only a set of antenna windings and bias field coil which produces significant thrust of 0.74 mN with rotating magnetic field has been proposed and successfully developed for future applications to low altitude nanosatellites. The key technology issue is that the rotating speed is set above the ion plasma frequency but far below the electron plasma frequency, in order to produce the electron drag current and axial electric field as a consequence of the interaction with the bias field. The formation of axial electric field was confirmed and the produced plasma density was >6x10{sup 18} m{sup -3}, whereas the power consumption is 500 W in the inductively coupled mode of operation. The anticipated thrust density and specific thrust could potentially be extended to 7.64 Nm{sup -2} and 850 s, respectively, which is comparable to conventional Hall effect thrusters.

  16. Methods, systems and devices for detecting threatening objects and for classifying magnetic data

    DOEpatents

    Kotter, Dale K.; Roybal, Lyle G.; Rohrbaugh, David T.; Spencer, David F.

    2012-01-24

    A method for detecting threatening objects in a security screening system. The method includes a step of classifying unique features of magnetic data as representing a threatening object. Another step includes acquiring magnetic data. Another step includes determining if the acquired magnetic data comprises a unique feature.

  17. Compact magnetic-field sensor based on optical microfiber Michelson interferometer and Fe3O4 nanofluid.

    PubMed

    Deng, Ming; Sun, Xiaokang; Han, Meng; Li, Decai

    2013-02-01

    We report a magnetic-field sensor by merging the advantages of optical fiber Michelson interferometers with that of magnetic fluid. Compact and low-cost optical fiber Michelson interferometers were first fabricated by a high-frequency CO(2) laser, and then they were inserted into glass capillaries with water-based Fe(3)O(4) magnetic fluid as sensing elements. The sensing characteristics have been investigated and the experimental results show that the reflective spectrum of the fiber-magnetic sensor linearly shifted with the change of the magnetic-field strength that is perpendicular to the axial of the devices. The fiber-magnetic sensor with interference arm's diameter of 50 μm is most sensitive to the external magnetic field, and the sensitivity is up to 64.9 pm/mT, which is 20 times higher than that of 125 μm diameter. PMID:23385914

  18. Numerical Study to Obtain the Improved Field Homogeneity and Enlarged Inner Diameter of HTS Bulk Magnet for Compact NMR

    NASA Astrophysics Data System (ADS)

    Miyazawa, D.; Kim, S. B.; Kitamura, H.; Ishizuka, D.; Hojo, K.

    We have been studying the compact magnet for NMR device that consists of a stacked high temperature superconducting (HTS) GdBCO bulk annuli. We can generate the trapped magnetic field over 1.5 T at 77.4 K and 150 ppm/cm3 on inner diameter of 20 mm HTS bulks using field compensation methods. However, it is necessary to enlarge the inner diameter of the HTS bulk magnet because the diameter of commercial NMR probe is larger than 20 mm. In this paper, we studied an optimal shape of the stacked HTS bulk magnet to obtain the enlarged inner diameter using 3-D FEM based analysis. We was able to enlarge the inner diameter of the HTS bulk magnet from 20 mm to 34 mm remaining magnetic field strength of 1.5 T and magnetic field homogeneity of 666 ppm/cm3 by proposed passive field compensation method.

  19. Three-dimensional spectroscopy of local luminous compact blue galaxies: kinematic maps of a sample of 22 objects

    NASA Astrophysics Data System (ADS)

    Pérez-Gallego, J.; Guzmán, R.; Castillo-Morales, A.; Gallego, J.; Castander, F. J.; Garland, C. A.; Gruel, N.; Pisano, D. J.; Zamorano, J.

    2011-12-01

    We use three-dimensional optical spectroscopy observations of a sample of 22 local luminous compact blue galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disc (RD), perturbed rotation (PR) and complex kinematics (CK). We find 48 per cent are RDs, 28 per cent are PRs and 24 per cent are CKs. RDs show rotational velocities that range between ˜50 and ˜200 km s-1, and dynamical masses that range between ˜1 × 109 and ˜3 × 1010 M⊙. We also address the following two fundamental questions through the study of the kinematic maps: (i) What processes are triggering the current starburst in LCBGs? We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find that 5 per cent of objects show evidence of a recent major merger, 10 per cent of a minor merger and 45 per cent of a companion. This argues in favour of ongoing interactions with close companions as a mechanism for the enhanced star formation activity in these galaxies. (ii) What processes may eventually quench the current starbust in LCBGs? Velocity and velocity width maps, together with emission line ratio maps, can reveal signatures of active galactic nuclei (AGNs) activity or supernova (SN)-driven galactic winds that could halt the current burst. We find only 5 per cent of objects with clear evidence of AGN activity and 27 per cent with kinematics consistent with SN-driven galactic winds. Therefore, a different mechanism may be responsible for quenching the star formation in LCBGs. Finally, from our analysis, we find that the velocity widths of RDs, rather than accounting exclusively for the rotational nature of these objects, may account as well for other kinematic components and may not be good tracers of their dynamical masses.

  20. Magnetic spin reduction system for free spinning objects

    NASA Technical Reports Server (NTRS)

    Vontiesenhausen, G. F. (Inventor)

    1986-01-01

    A spinning Earth satellite is shown in which it is desired to reduce the rotation or spin to a level that the satellite may be secured or handled remotely from a spacecraft. This is accomplished by the spacecraft having a mast carrying an electrical current coil which encircles the satellite. The magnetic field of the coil is normal to the spin axis of the satellite which causes circular eddy current flow in the housing of the satellite. This generates magnetic force opposing the rotation. In another embodiment the magnetic field is generated by the use of an electromagnet on a remote manipulation arm.

  1. Apparatus and method for generating a magnetic field by rotation of a charge holding object

    DOEpatents

    Gerald, II, Rex E.; Vukovic, Lela; Rathke, Jerome W.

    2009-10-13

    A device and a method for the production of a magnetic field using a Charge Holding Object that is mechanically rotated. In a preferred embodiment, a Charge Holding Object surrounding a sample rotates and subjects the sample to one or more magnetic fields. The one or more magnetic fields are used by NMR Electronics connected to an NMR Conductor positioned within the Charge Holding Object to perform NMR analysis of the sample.

  2. A Large-Particle Monte Carlo Code for Simulating Non-Linear High-Energy Processes Near Compact Objects

    NASA Technical Reports Server (NTRS)

    Stern, Boris E.; Svensson, Roland; Begelman, Mitchell C.; Sikora, Marek

    1995-01-01

    High-energy radiation processes in compact cosmic objects are often expected to have a strongly non-linear behavior. Such behavior is shown, for example, by electron-positron pair cascades and the time evolution of relativistic proton distributions in dense radiation fields. Three independent techniques have been developed to simulate these non-linear problems: the kinetic equation approach; the phase-space density (PSD) Monte Carlo method; and the large-particle (LP) Monte Carlo method. In this paper, we present the latest version of the LP method and compare it with the other methods. The efficiency of the method in treating geometrically complex problems is illustrated by showing results of simulations of 1D, 2D and 3D systems. The method is shown to be powerful enough to treat non-spherical geometries, including such effects as bulk motion of the background plasma, reflection of radiation from cold matter, and anisotropic distributions of radiating particles. It can therefore be applied to simulate high-energy processes in such astrophysical systems as accretion discs with coronae, relativistic jets, pulsar magnetospheres and gamma-ray bursts.

  3. Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

    NASA Astrophysics Data System (ADS)

    Horton, W.; Ditmire, T.; Zakharov, Yu. P.

    2010-06-01

    Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

  4. Design of a compact all-permanent magnet ECR ion source injector for ReA at the MSU NSCL

    NASA Astrophysics Data System (ADS)

    Pham, Alfonse N.; Leitner, Daniela; Glennon, Patrick; Ottarson, Jack; Lawton, Don; Portillo, Mauricio; Machicoane, Guillaume; Wenstrom, John; Lajoie, Andrew

    2016-06-01

    The design of a compact all-permanent magnet electron cyclotron resonance (ECR) ion source injector for the ReAccelerator Facility (ReA) at the Michigan State University (MSU) National Superconducting Cyclotron Laboratory (NSCL) is currently being carried out. The ECR ion source injector will complement the electron beam ion trap (EBIT) charge breeder as an off-line stable ion beam injector for the ReA linac. The objective of the ECR ion source injector is to provide continuous-wave beams of heavy ions from hydrogen to masses up to 136Xe within the ReA charge-to-mass ratio (Q / A) operational range from 0.2 to 0.5. The ECR ion source will be mounted on a high-voltage platform that can be adjusted to obtain the required 12 keV/u injection energy into a room temperature radio-frequency quadrupole (RFQ) for further acceleration. The beam line consists of a 30 kV tetrode extraction system, mass analyzing section, and optical matching section for injection into the existing ReA low energy beam transport (LEBT) line. The design of the ECR ion source and the associated beam line are discussed.

  5. Mars Environment and Magnetic Orbiter Scientific and Measurement Objectives

    NASA Astrophysics Data System (ADS)

    Leblanc, F.; Langlais, B.; Fouchet, T.; Barabash, S.; Breuer, D.; Chassefière, E.; Coates, A.; Dehant, V.; Forget, F.; Lammer, H.; Lewis, S.; Lopez-Valverde, M.; Mandea, M.; Menvielle, M.; Pais, A.; Paetzold, M.; Read, P.; Sotin, C.; Tarits, P.; Vennerstrom, S.

    2009-02-01

    In this paper, we summarize our present understanding of Mars' atmosphere, magnetic field, and surface and address past evolution of these features. Key scientific questions concerning Mars' surface, atmosphere, and magnetic field, along with the planet's interaction with solar wind, are discussed. We also define what key parameters and measurements should be performed and the main characteristics of a martian mission that would help to provide answers to these questions. Such a mission -- Mars Environment and Magnetic Orbiter (MEMO) -- was proposed as an answer to the Cosmic Vision Call of Opportunity as an M-class mission (corresponding to a total European Space Agency cost of less than 300 M€). MEMO was designed to study the strong interconnection between the planetary interior, atmosphere, and solar conditions, which is essential to our understanding of planetary evolution, the appearance of life, and its sustainability. The MEMO main platform combined remote sensing and in situ measurements of the atmosphere and the magnetic field during regular incursions into the martian upper atmosphere. The micro-satellite was designed to perform simultaneous in situ solar wind measurements. MEMO was defined to conduct: • Four-dimensional mapping of the martian atmosphere from the surface up to 120 km by measuring wind, temperature, water, and composition, all of which would provide a complete view of the martian climate and photochemical system; • Mapping of the low-altitude magnetic field with unprecedented geographical, altitude, local time, and seasonal resolutions; • A characterization of the simultaneous responses of the atmosphere, magnetic field, and near-Mars space to solar variability by means of in situ atmospheric and solar wind measurements.

  6. Mars environment and magnetic orbiter scientific and measurement objectives.

    PubMed

    Leblanc, F; Langlais, B; Fouchet, T; Barabash, S; Breuer, D; Chassefière, E; Coates, A; Dehant, V; Forget, F; Lammer, H; Lewis, S; Lopez-Valverde, M; Mandea, M; Menvielle, M; Pais, A; Paetzold, M; Read, P; Sotin, C; Tarits, P; Vennerstrom, S

    2009-01-01

    In this paper, we summarize our present understanding of Mars' atmosphere, magnetic field, and surface and address past evolution of these features. Key scientific questions concerning Mars' surface, atmosphere, and magnetic field, along with the planet's interaction with solar wind, are discussed. We also define what key parameters and measurements should be performed and the main characteristics of a martian mission that would help to provide answers to these questions. Such a mission--Mars Environment and Magnetic Orbiter (MEMO)--was proposed as an answer to the Cosmic Vision Call of Opportunity as an M-class mission (corresponding to a total European Space Agency cost of less than 300 Meuro). MEMO was designed to study the strong interconnection between the planetary interior, atmosphere, and solar conditions, which is essential to our understanding of planetary evolution, the appearance of life, and its sustainability. The MEMO main platform combined remote sensing and in situ measurements of the atmosphere and the magnetic field during regular incursions into the martian upper atmosphere. The micro-satellite was designed to perform simultaneous in situ solar wind measurements. MEMO was defined to conduct: * Four-dimensional mapping of the martian atmosphere from the surface up to 120 km by measuring wind, temperature, water, and composition, all of which would provide a complete view of the martian climate and photochemical system; Mapping of the low-altitude magnetic field with unprecedented geographical, altitude, local time, and seasonal resolutions; A characterization of the simultaneous responses of the atmosphere, magnetic field, and near-Mars space to solar variability by means of in situ atmospheric and solar wind measurements. PMID:19317625

  7. Fabrication of fully dense nanostructured MnBi magnet by hot compaction of cryo-milled powders

    NASA Astrophysics Data System (ADS)

    Hadjipanayis, George; Neelam, Venkata; Gabay, Alex; Li, Wang

    2013-03-01

    Recently, rare-earth-free permanent magnets (REFPMs) have attracted much attention globally owing to rare-earth metal crisis and high cost. Among the REFPMs, MnBi is a potential candidate due to its unusual large magnetocrystalline anisotropy (K ~ 107 erg/cc) and positive temperature of coefficient of coercivity. In this work, we report for the first time a novel processing method that combines the cryo-milling with hot compaction to produce fully dense bulk nanostructured MnBi magnet. The effect of cryo-milling on particle size, phase formation, and magnetic properties of MnBi has been studied in detail. Also, the microstructural and magnetic properties of bulk nanostructured MnBi magnet were investigated. Adoption of cryo-milling results in nanocrystalline powders with particle size of 400-500 nm. Large coercivity (Hc) values of 18.5 kOe, and 12.9 kOe were obtained in cryo-milled powders and hot compacted magnet respectively. The MnBi magnet shows a large positive temperature coefficient of Hc and the Hc reaches a value of more than 30 kOe above 450 K. The work was supported by Siemens.

  8. Effect of ball milling and dynamic compaction on magnetic properties of Al2O3/Co(P) composite particles

    NASA Astrophysics Data System (ADS)

    Denisova, E. A.; Kuzovnikova, L. A.; Iskhakov, R. S.; Bukaemskiy, A. A.; Eremin, E. V.; Nemtsev, I. V.

    2014-05-01

    The evolution of the magnetic properties of composite Al2O3/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al2O3 granules were coated with a Co95P5 shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al2O3 powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

  9. Magnetic and magneto elastic properties of cobalt ferrite ceramic compacted through cold isostatic pressing

    NASA Astrophysics Data System (ADS)

    Indla, Srinivas; Chelvane, Arout; Das, Dibakar

    2016-05-01

    Nano crystalline CoFe2O4 powder was prepared by combustion synthesis method. As synthesized powder was calcined at an appropriate condition to remove the impurities and to promote phase formation. Phase pure CoFe2O4 powder was pressed into cylindrical rod at an applied pressure of 200 MPa using a cold isostatic pressing. Sintering of the green compact at 1350°c for 12 hrs resulted in sintered cylindrical rod with ~85% of the theoretical density. Single phase cubic spinel structure was observed in the powder x-ray diffraction pattern of the sintered pellet. Scanning electron micrographs (SEM) of the as sintered pellet revealed the microstructure to be composed of ferrite grains of average size ~4 µm. Saturation magnetization of 72 emu/g and coercivity of 355 Oe were observed for cobalt ferrite sample. The magnetostriction was measured on a circular disc (12mm diameter and 12mm length) with the strain gauge (350 Ω) mounted on the flat surface of the circular disc. Magnetostriciton of 180 ppm and strain derivative of 1 × 10-9 m/A were observed for the sintered CoFe2O4 sample.

  10. The Cluster magnetic field investigation: Scientific objectives and instrumentation

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Cowley, S. W. H.; Dunlop, M. W.; Southwood, D. J.; Thomlinson, J. G.; Glassmeier, K. H.; Musmann, G.; Luehr, H.; Acuna, M. H.; Fairfield, D. H.

    1993-01-01

    The Cluster magnetic field investigation is presented. Cluster represents a qualitatively new type of space mission which will provide, for the first time, a three dimensional view of small scale plasma processes and structures in the different regions in and around the Earth's magnetosphere. Concepts of data analysis needed to interpret the four spacecraft magnetic field data in terms of magnetospheric processes and structures are outlined. The instrument itself, a vital component of the scientific payload, follows a long tradition of fluxgate magnetometers on space missions, yet represents an evolution in terms of built in functions and reliability. A detailed description of the instrument is given with emphasis on those aspects that are unique to the mission.

  11. Non-thermal Radiation from Collisions of Compact Objects with Intermediate-scale Jets in Active Galaxies

    NASA Astrophysics Data System (ADS)

    Bednarek, W.; Banasiński, P.

    2015-07-01

    Massive black holes in active galaxies are immersed in huge concentrations of late-type stars in the galactic bulges and also early-type massive stars in the nuclear stellar clusters, which are additionally surrounded by quasi-spherical halos on a scale of several kpc that contain from a few hundred up to several thousand globular clusters (GCs). It is expected that significant numbers of red giant stars, massive stars, and also GCs can move through the jet expelled from the central engine of the active galaxy. We consider collisions of stars from the galactic bulge, nuclear cluster, and GCs with the jet plasma. As a result of such collisions, multiple shocks are expected to appear in the jet around these compact objects. Therefore, the plasma in the kpc-scale jet can be significantly disturbed. We show that particles can be accelerated on these shocks up to multi-TeV energies. TeV leptons emit synchrotron radiation, extending up to X-ray energies, and also comptonize radiation produced in a stellar cluster and also the microwave background radiation to TeV γ-ray energies. We show that such non-thermal radiation is likely to be detectable from the intermediate-scale jets of nearby active galaxies for a reasonable number of stars and GCs immersed within the jet. As an example, we calculate the expected non-thermal emission in X-ray and gamma-ray energies from the nearby radio galaxy Cen A, from which steady gamma-ray emission with a complex spectrum has recently been reported by Fermi and the HESS Observatories.

  12. Micro-tidal Disruption Events by Stellar Compact Objects and the Production of Ultra-long GRBs

    NASA Astrophysics Data System (ADS)

    Perets, Hagai B.; Li, Zhuo; Lombardi, James C., Jr.; Milcarek, Stephen R., Jr.

    2016-06-01

    We explore full/partial tidal disruption events (TDEs) of stars/planets by stellar compact objects (black holes (BHs) or neutron stars (NSs)), which we term micro-TDEs. Disruption of a star/planet with mass M ⋆ may lead to the formation of a debris disk around the BH/NS. Efficient accretion of a fraction ({f}{acc}=0.1 of the debris may then give rise to bright, energetic, long (103–104 s), X-ray/gamma-ray flares, with total energies of up to ({f}{acc}/0.1)× {10}52 ({M}\\star /0.6 {M}ȯ ) erg, possibly resembling ultra-long gamma-ray bursts (GRBs)/X-ray flashes (XRFs). The energy of such flares depends on the poorly constrained accretion processes. Significantly fainter flares might be produced if most of the disk mass is blown away through strong outflows. We suggest three dynamical origins for such disruptions. In the first, a star/planet is tidally disrupted following a close random encounter with a BH/NS in a dense cluster. We estimate the BH (NS) micro-TDE rates from this scenario to be a few × {10}-6 (a few × {10}-7) {{{yr}}}-1 per Milky Way galaxy. Another scenario involves the interaction of wide companions due to perturbations by stars in the field, likely producing comparable but lower rates. Finally, a third scenario involves a BH/NS that gains a natal velocity kick at birth, leading to a close encounter with a binary companion and the tidal disruption of that companion. Such events could be associated with a supernova, or even with a preceding GRB/XRF event, and would likely occur hours to days after the prompt explosion; the rates of such events could be larger than those obtained from the other scenarios, depending on the preceding complex binary stellar evolution.

  13. On the Nature of Compact Object in SS~433. An Observational Evidence of Black Hole Mass in SS 433

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev

    We present an analysis of X-ray spectral properties observed from black hole candidate (BHC) binary SS 433. We analyze RXTE data from this source, coordinated with Green Bank Interferometer/RATAN-600. We show that SS 433 demonstrates a X-ray spectral transition from low hard state to intermediate state (IS). We show that the X-ray broad-band energy spectra during all spectral states are well fit by a sum of so called "Bulk Motion Comptoniza-tion (BMC)" component and by two (broad and narrow) Gaussians for the continuum and line emissions respectively. In addition to these spectral model components we also find a strong feature of "blackbody-like (BB)" bump which color temperature is in the range of 4-5 keV in 24 IS spectra during radio outburst decay in SS 433. Our observational results on the "high temperature BB" bump leads us to support the presence of gravitationally redshifted annihila-tion lines in this source. We also established the photon index saturation at about 2.3 in index vs mass accretion correlation. This index-mass accretion correlation allows us to evaluate the low limit of black hole (BH) mass of compact object in SS 433, greater than 2 solar masses, using the scaling method using BHC GX 339-4 as a reference source. Our estimate of BH mass in SS 433 is consistent with the recent BH mass measurement by Hillwig Gies who find that BH mass about 4.3 solar masses. It is the smallest BH mass up to now found among all BHC sources where BH masses have been estimated so far. Moreover, the index saturation effect versus mass accretion rate revealed in SS 433, like in a number of other BHCs, is the strongest observational evidence of the presence of BH in SS 433.

  14. EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS

    SciTech Connect

    Barnes, Jennifer; Kasen, Daniel

    2013-09-20

    The coalescence of compact objects is a promising astrophysical source of detectable gravitational wave signals. The ejection of r-process material from such mergers may lead to a radioactively powered electromagnetic counterpart signal which, if discovered, would enhance the science returns. As very little is known about the optical properties of heavy r-process elements, previous light-curve models have adopted opacities similar to those of iron group elements. Here we consider the effect of heavier elements, particularly the lanthanides, which increase the ejecta opacity by several orders of magnitude. We include these higher opacities in time-dependent, multi-wavelength radiative transport calculations to predict the broadband light curves of one-dimensional models over a range of parameters (ejecta masses {approx}10{sup -3}-10{sup -1} M{sub Sun} and velocities {approx}0.1-0.3 c). We find that the higher opacities lead to much longer duration light curves which can last a week or more. The emission is shifted toward the infrared bands due to strong optical line blanketing, and the colors at later times are representative of a blackbody near the recombination temperature of the lanthanides (T {approx} 2500 K). We further consider the case in which a second mass outflow, composed of {sup 56}Ni, is ejected from a disk wind, and show that the net result is a distinctive two component spectral energy distribution, with a bright optical peak due to {sup 56}Ni and an infrared peak due to r-process ejecta. We briefly consider the prospects for detection and identification of these transients.

  15. Development of Compact Electron Cyclotron Resonance Ion Source with Permanent Magnets for High-Energy Carbon-Ion Therapy

    SciTech Connect

    Muramatsu, M.; Kitagawa, A.; Iwata, Y.; Hojo, S.; Sakamoto, Y.; Sato, S.; Ogawa, Hirotsugu; Yamada, S.; Ogawa, Hiroyuki; Yoshida, Y.; Ueda, T.; Miyazaki, H.; Drentje, A. G.

    2008-11-03

    Heavy-ion cancer treatment is being carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC) with 140 to 400 MeV/n carbon ions at National Institute of Radiological Sciences (NIRS) since 1994. At NIRS, more than 4,000 patients have been treated, and the clinical efficiency of carbon ion radiotherapy has been demonstrated for many diseases. A more compact accelerator facility for cancer therapy is now being constricted at the Gunma University. In order to reduce the size of the injector (consists of ion source, low-energy beam transport and post-accelerator Linac include these power supply and cooling system), an ion source requires production of highly charged carbon ions, lower electric power for easy installation of the source on a high-voltage platform, long lifetime and easy operation. A compact Electron Cyclotron Resonance Ion Source (ECRIS) with all permanent magnets is one of the best types for this purpose. An ECRIS has advantage for production of highly charged ions. A permanent magnet is suitable for reduce the electric power and cooling system. For this, a 10 GHz compact ECRIS with all permanent magnets (Kei2-source) was developed. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas-injection side, while the minimum B strength is 0.25 T. These parameters have been optimized for the production of C{sup 4+} based on experience at the 10 GHz NIRS-ECR ion source. The Kei2-source has a diameter of 320 mm and a length of 295 mm. The beam intensity of C{sup 4+} was obtained to be 618 e{mu}A under an extraction voltage of 30 kV. Outline of the heavy ion therapy and development of the compact ion source for new facility are described in this paper.

  16. Development of Compact Electron Cyclotron Resonance Ion Source with Permanent Magnets for High-Energy Carbon-Ion Therapy

    NASA Astrophysics Data System (ADS)

    Muramatsu, M.; Kitagawa, A.; Iwata, Y.; Hojo, S.; Sakamoto, Y.; Sato, S.; Ogawa, Hirotsugu; Yamada, S.; Ogawa, Hiroyuki; Yoshida, Y.; Ueda, T.; Miyazaki, H.; Drentje, A. G.

    2008-11-01

    Heavy-ion cancer treatment is being carried out at the Heavy Ion Medical Accelerator in Chiba (HIMAC) with 140 to 400 MeV/n carbon ions at National Institute of Radiological Sciences (NIRS) since 1994. At NIRS, more than 4,000 patients have been treated, and the clinical efficiency of carbon ion radiotherapy has been demonstrated for many diseases. A more compact accelerator facility for cancer therapy is now being constricted at the Gunma University. In order to reduce the size of the injector (consists of ion source, low-energy beam transport and post-accelerator Linac include these power supply and cooling system), an ion source requires production of highly charged carbon ions, lower electric power for easy installation of the source on a high-voltage platform, long lifetime and easy operation. A compact Electron Cyclotron Resonance Ion Source (ECRIS) with all permanent magnets is one of the best types for this purpose. An ECRIS has advantage for production of highly charged ions. A permanent magnet is suitable for reduce the electric power and cooling system. For this, a 10 GHz compact ECRIS with all permanent magnets (Kei2-source) was developed. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas-injection side, while the minimum B strength is 0.25 T. These parameters have been optimized for the production of C4+ based on experience at the 10 GHz NIRS-ECR ion source. The Kei2-source has a diameter of 320 mm and a length of 295 mm. The beam intensity of C4+ was obtained to be 618 eμA under an extraction voltage of 30 kV. Outline of the heavy ion therapy and development of the compact ion source for new facility are described in this paper.

  17. Compact-device model development for the energy-delay analysis of magneto-electric magnetic tunnel junction structures

    NASA Astrophysics Data System (ADS)

    Sharma, N.; Bird, J. P.; Dowben, P. A.; Marshall, A.

    2016-06-01

    We discuss the application of a novel class of device, the magneto-electric magnetic tunnel junction (ME-MTJ) to realize a variety of computational functions, including majority logic and the XNOR/XOR gate. We also develop a compact model to describe the operation of these devices, which function by utilizing the phenomenon of ‘voltage-controlled magnetism’ to switch the operational state of MTJs. The model breaks down the switching process into three key stages of operation: electrical-to-magnetic conversion, magnetization transfer, and final-state readout. Estimates for the switching energy and delay of these devices, obtained from this compact model, reveal significant improvements in both of these parameters when compared to conventional MTJs switched by spin-transfer-torque. In fact, the capacity to use the ME-MTJ to implement complex logical operations within a single device allows its energy costs to even approach those of low-power CMOS. The added benefits of non-volatility and compact circuit footprint, combined with their potential for heterogeneous integration with CMOS, make the ME devices of considerable interest for post-CMOS technology.

  18. Trapped Field Characteristics of Stacked YBCO Thin Plates for Compact NMR Magnets: Spatial Field Distribution and Temporal Stability.

    PubMed

    Hahn, Seungyong; Kim, Seok Beom; Ahn, Min Cheol; Voccio, John; Bascuñán, Juan; Iwasa, Yukikazu

    2010-06-01

    This paper presents experimental and analytical results of trapped field characteristics of a stack of square YBCO thin film plates for compact NMR magnets. Each YBCO plate, 40 mm × 40 mm × 0.08 mm, has a 25-mm diameter hole at its center. A total of 500 stacked plates were used to build a 40-mm long magnet. Its trapped field, in a bath of liquid nitrogen, was measured for spatial field distribution and temporal stability. Comparison of measured and analytical results is presented: the effects on trapped field characteristics of the unsaturated nickel substrate and the non-uniform current distribution in the YBCO plate are discussed. PMID:20585463

  19. Effect of Object Orientation Angle on T2* Image and Reconstructed Magnetic Susceptibility: Numerical Simulations

    PubMed Central

    Chen, Zikuan; Calhoun, Vince

    2013-01-01

    The magnetic field resulting from material magnetization in magnetic resonance imaging (MRI) has an object orientation effect, which produces an orientation dependence for acquired T2* images. On one hand, the orientation effect can be exploited for object anisotropy investigation (via multi-angle imaging); on the other hand, it is desirable to remove the orientation dependence using magnetic susceptibility reconstruction. In this report, we design a stick-star digital phantom to simulate multiple orientations of a stick-like object and use it to conduct various numerical simulations. Our simulations show that the object orientation effect is not propagated to the reconstructed magnetic susceptibility distribution. This suggests that accurate susceptibility reconstruction methods should be largely orientation independent. PMID:25114542

  20. On the Nature of the Compact Object in SS 433: Observational Evidence of X-ray Photon Index Saturation

    NASA Astrophysics Data System (ADS)

    Seifina, Elena; Titarchuk, Lev

    2010-10-01

    We present an analysis of the X-ray spectral properties observed from the black hole candidate (BHC) binary SS 433. We have analyzed Rossi X-ray Timing Explorer data from this source, coordinated with Green Bank Interferometer/RATAN-600. We show that SS 433 undergoes an X-ray spectral transition from the low hard state to the intermediate state (IS). We show that the X-ray broadband energy spectra during all spectral states are well fitted by a sum of the so-called bulk motion Comptonization (BMC) component and by two (broad and narrow) Gaussians for the continuum and line emissions, respectively. In addition to these spectral model components, we also find a strong feature that we identify as a "blackbody-like (BB)" component in which the color temperature is in the range of 4-5 keV in 24 IS spectra during the radio outburst decay in SS 433. Our observational results on the "high-temperature BB" bump lead us to suggest the presence of gravitationally redshifted annihilation line emission in this source. In fact, this spectral feature has been recently reproduced in Monte Carlo simulations by Laurent & Titarchuk. We have also established the photon index saturation at about 2.3 in index versus mass accretion correlation. This index-mass accretion correlation allows us to evaluate the low limit of the black hole (BH) mass of the compact object in SS 433, M_{{bh}}≳ 2 solar masses, using the scaling method using BHC GX 339 - 4 as a reference source. Our estimate of the BH mass in SS 433 is consistent with the recent BH mass measurement using the radial velocity measurements of the binary system by Hillwig & Gies, who find that Mx = (4.3 ± 0.8) solar masses. This is the smallest BH mass found up to now among all BH sources. Moreover, the index saturation effect versus mass accretion rate revealed in SS 433, as in a number of other BH candidates, is strong observational evidence for the presence of a BH in SS 433.

  1. ON THE NATURE OF THE COMPACT OBJECT IN SS 433: OBSERVATIONAL EVIDENCE OF X-RAY PHOTON INDEX SATURATION

    SciTech Connect

    Seifina, Elena

    2010-10-10

    We present an analysis of the X-ray spectral properties observed from the black hole candidate (BHC) binary SS 433. We have analyzed Rossi X-ray Timing Explorer data from this source, coordinated with Green Bank Interferometer/RATAN-600. We show that SS 433 undergoes an X-ray spectral transition from the low hard state to the intermediate state (IS). We show that the X-ray broadband energy spectra during all spectral states are well fitted by a sum of the so-called bulk motion Comptonization (BMC) component and by two (broad and narrow) Gaussians for the continuum and line emissions, respectively. In addition to these spectral model components, we also find a strong feature that we identify as a 'blackbody-like (BB)' component in which the color temperature is in the range of 4-5 keV in 24 IS spectra during the radio outburst decay in SS 433. Our observational results on the 'high-temperature BB' bump lead us to suggest the presence of gravitationally redshifted annihilation line emission in this source. In fact, this spectral feature has been recently reproduced in Monte Carlo simulations by Laurent and Titarchuk. We have also established the photon index saturation at about 2.3 in index versus mass accretion correlation. This index-mass accretion correlation allows us to evaluate the low limit of the black hole (BH) mass of the compact object in SS 433, M{sub bh{approx}}>2 solar masses, using the scaling method using BHC GX 339 - 4 as a reference source. Our estimate of the BH mass in SS 433 is consistent with the recent BH mass measurement using the radial velocity measurements of the binary system by Hillwig and Gies, who find that M{sub x} = (4.3 {+-} 0.8) solar masses. This is the smallest BH mass found up to now among all BH sources. Moreover, the index saturation effect versus mass accretion rate revealed in SS 433, as in a number of other BH candidates, is strong observational evidence for the presence of a BH in SS 433.

  2. On the Nature of the Compact Object in SS 433. Observational Evidence of X-Ray Photon Index Saturation

    NASA Technical Reports Server (NTRS)

    Seifina, Elena; Titarchuk, Lev

    2010-01-01

    We present an analysis of the X-ray spectral properties observed from black hole , candidate (BHC) binary SS 433. We have analyzed Rossi X-ray Time Explorer (RXTE) data from this source, coordinated with Green Bank Interferometer/RATAN-600. We show that SS 433 undergoes a X-ray spectral transition from the low hard state (LHS) to the intermediate state (IS). We show that the X-ray broad-band energy spectra during all spectral states are well fit by a sum of so called "Bulk Motion Comptonization (BMC) component" and by two (broad and narrow) Gaussians for the continuum and line emissions respectively. In addition to these spectral model components we also find a strong feature that we identify as a" blackbody-like (BB)" component which color temperature is in the range of 4-5 keV in 24 IS spectra during the radio outburst decay in SS 433. Our observational results on the "high temperature BB" bump leads us to suggest the presence of gravitationally redshifted annihilation line emission in this source. In fact this spectral feature has been recently reproduced in Monte Carlo simulations by Laurent and Titarchuk. We have also established the photon index saturation at about 2.3 in index vs mass accretion correlation. This index-mass accretion correlation allows us to evaluate the low limit of black hole (BH) mass of compact object in SS 433, M(sub bh) approximately > 2 solar masses, using the scaling method using BHC GX 339-4 as a reference source. Our estimate of the BH mass in SS 433 is consistent with recent BH mass measurement using the radial-velocity measurements of the binary system by Hillwig & Gies who find that M(sub x)( = (4.3 +/- 0.8) solar masses. This is the smallest BH mass found up to now among all BH sources. Moreover, the index saturation effect versus mass accretion rate revealed in SS 433, like in a number of other BH candidates, is the strong observational evidence for the presence of a BH in SS 433.

  3. Influence of the type of surfactant and hot compaction on the magnetic properties of SmCo5 nanoflakes

    NASA Astrophysics Data System (ADS)

    Zheng, Liyun; Gabay, Alexander M.; Li, Wanfeng; Cui, Baozhi; Hadjipanayis, George C.

    2011-04-01

    In this study, we discuss the effects of a type of surfactant (oleylamine, oleic acid, and trioctylamine) and hot pressing on the hard magnetic properties of crystallographically anisotropic SmCo5 nanoflakes prepared by surfactant-assisted high energy ball milling. The phase, microstructure, and magnetic properties of the hot-pressed SmCo5 were investigated by using x-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The coercivities of the precursor flakes prepared using oleylamine, oleic acid, and trioctylamine were 14.9, 15.8, and 15 kOe, respectively. Hot-compacted SmCo5 magnets prepared from the nanoflakes milled with oleic acid had the lowest coercivity of 8.1 kOe. It is believed that even after repeated washing in an ultrasonic bath with different solvents, the remaining oleic acid in the SmCo5 nanoflakes led to oxidation of SmCo5 at the surface/interface of nanoflakes during the hot-pressing process. The compacted SmCo5 magnets prepared from the nanoflakes milled with trioctylamine and oleylamine had higher coercivity values of 14.8 and 12.8 kOe, respectively. Unlike oleic acid, oleylamine and trioctylamine contain no oxygen atoms, and therefore there was less oxidation during the process. The compaction temperature also influences the coercivity. The SmCo5 magnets hot pressed at 550 °C had the highest coercivity, whereas those hot pressed at 650 °C had the lowest coercivity; this is attributed to the change of phases and composition of SmCo5 alloys during the hot-pressing process.

  4. Bolometer detection of magnetic resonances in nanoscaled objects.

    PubMed

    Rod, Irina; Meckenstock, Ralf; Zähres, Horst; Derricks, Christian; Mushenok, Fedor; Reckers, Nathalie; Kijamnajsuk, Puchong; Wiedwald, Ulf; Farle, Michael

    2014-10-24

    We report on a nanoscaled thermocouple (ThC) as a temperature sensor of a highly sensitive bolometer for probing the dissipative damping of spin dynamics in nanosized Permalloy (Py) stripes. The Au-Pd ThC based device is fabricated by standard electron beam lithography on a 200 nm silicon nitride membrane to minimize heat dissipation through the substrate. We show that this thermal sensor allows not only measurements of the temperature change on the order of a few mK due to the uniform resonant microwave (MW) absorption by the Py stripe but also detection of standing spin waves of different mode numbers. Using a 3D finite element method, we estimate the absorbed MW power by the stripe in resonance and prove the necessity of using substrates with an extremely low heat dissipation like a silicon nitride membrane for successful thermal detection. The voltage responsivity and the noise equivalent power for the ThC-based bolometer are equal to 15 V W(-1) and 3 nW Hz(-1/2), respectively. The ThC device offers a magnetic resonance response of 1 nV/(μ(B) W) corresponding to a sensitivity of 10(9) spins and a temperature resolution of 300 μK under vacuum conditions. PMID:25271896

  5. Bolometer detection of magnetic resonances in nanoscaled objects

    NASA Astrophysics Data System (ADS)

    Rod, Irina; Meckenstock, Ralf; Zähres, Horst; Derricks, Christian; Mushenok, Fedor; Reckers, Nathalie; Kijamnajsuk, Puchong; Wiedwald, Ulf; Farle, Michael

    2014-10-01

    We report on a nanoscaled thermocouple (ThC) as a temperature sensor of a highly sensitive bolometer for probing the dissipative damping of spin dynamics in nanosized Permalloy (Py) stripes. The Au-Pd ThC based device is fabricated by standard electron beam lithography on a 200 nm silicon nitride membrane to minimize heat dissipation through the substrate. We show that this thermal sensor allows not only measurements of the temperature change on the order of a few mK due to the uniform resonant microwave (MW) absorption by the Py stripe but also detection of standing spin waves of different mode numbers. Using a 3D finite element method, we estimate the absorbed MW power by the stripe in resonance and prove the necessity of using substrates with an extremely low heat dissipation like a silicon nitride membrane for successful thermal detection. The voltage responsivity and the noise equivalent power for the ThC-based bolometer are equal to 15 V W-1 and 3 nW Hz-1/2, respectively. The ThC device offers a magnetic resonance response of 1 nV/(μB W) corresponding to a sensitivity of 109 spins and a temperature resolution of 300 μK under vacuum conditions.

  6. Noncontact orientation of objects in three-dimensional space using magnetic levitation.

    PubMed

    Subramaniam, Anand Bala; Yang, Dian; Yu, Hai-Dong; Nemiroski, Alex; Tricard, Simon; Ellerbee, Audrey K; Soh, Siowling; Whitesides, George M

    2014-09-01

    This paper describes several noncontact methods of orienting objects in 3D space using Magnetic Levitation (MagLev). The methods use two permanent magnets arranged coaxially with like poles facing and a container containing a paramagnetic liquid in which the objects are suspended. Absent external forcing, objects levitating in the device adopt predictable static orientations; the orientation depends on the shape and distribution of mass within the objects. The orientation of objects of uniform density in the MagLev device shows a sharp geometry-dependent transition: an analytical theory rationalizes this transition and predicts the orientation of objects in the MagLev device. Manipulation of the orientation of the levitating objects in space is achieved in two ways: (i) by rotating and/or translating the MagLev device while the objects are suspended in the paramagnetic solution between the magnets; (ii) by moving a small external magnet close to the levitating objects while keeping the device stationary. Unlike mechanical agitation or robotic selection, orienting using MagLev is possible for objects having a range of different physical characteristics (e.g., different shapes, sizes, and mechanical properties from hard polymers to gels and fluids). MagLev thus has the potential to be useful for sorting and positioning components in 3D space, orienting objects for assembly, constructing noncontact devices, and assembling objects composed of soft materials such as hydrogels, elastomers, and jammed granular media. PMID:25157136

  7. Noncontact orientation of objects in three-dimensional space using magnetic levitation

    PubMed Central

    Subramaniam, Anand Bala; Yang, Dian; Yu, Hai-Dong; Nemiroski, Alex; Tricard, Simon; Ellerbee, Audrey K.; Soh, Siowling; Whitesides, George M.

    2014-01-01

    This paper describes several noncontact methods of orienting objects in 3D space using Magnetic Levitation (MagLev). The methods use two permanent magnets arranged coaxially with like poles facing and a container containing a paramagnetic liquid in which the objects are suspended. Absent external forcing, objects levitating in the device adopt predictable static orientations; the orientation depends on the shape and distribution of mass within the objects. The orientation of objects of uniform density in the MagLev device shows a sharp geometry-dependent transition: an analytical theory rationalizes this transition and predicts the orientation of objects in the MagLev device. Manipulation of the orientation of the levitating objects in space is achieved in two ways: (i) by rotating and/or translating the MagLev device while the objects are suspended in the paramagnetic solution between the magnets; (ii) by moving a small external magnet close to the levitating objects while keeping the device stationary. Unlike mechanical agitation or robotic selection, orienting using MagLev is possible for objects having a range of different physical characteristics (e.g., different shapes, sizes, and mechanical properties from hard polymers to gels and fluids). MagLev thus has the potential to be useful for sorting and positioning components in 3D space, orienting objects for assembly, constructing noncontact devices, and assembling objects composed of soft materials such as hydrogels, elastomers, and jammed granular media. PMID:25157136

  8. Cyclotron line formation in the magnetized atmospheres of compact stars - I. The transfer equations for polarized radiation

    NASA Astrophysics Data System (ADS)

    Garasev, M. A.; Derishev, E. V.; Kocharovsky, Vl. V.; Kocharovsky, V. V.

    2016-06-01

    We find the forms of the transfer equations for polarized cyclotron radiation in the atmospheres of compact stars, which are simple enough to allow practical implementation and still preserve all important physical effects. We take into account a frequency redistribution of radiation within the cyclotron line as well as the relativistic and quantum-electrodynamic effects. Our analysis is valid for the magnetic fields up to 1013 G and for temperatures well below 500 keV. We present and compare two forms of the radiation transfer equations. The first form, for the intensities of ordinary and extraordinary modes, is applicable for the compact stars with a moderate magnetic field strength up to 1011 G for typical neutron star and up to 109 G for magnetic white dwarfs. The second form, for the Stokes parameters, is more complex, but applicable even if a linear mode coupling takes place somewhere in the scattering-dominated atmosphere. Analysing dispersion properties of a magnetized plasma in the latter case, we describe a range of parameters where the linear mode coupling is possible and essential.

  9. Coalescing binary systems of compact objects to (post) sup 5/2 -Newtonian order: Late-time evolution and gravitational radiation emission

    SciTech Connect

    Lincoln, C.W.

    1990-01-01

    The late-time evolution of binary systems of compact objects (neutron stars or black holes) is studied using the Damour-Derueele (post){sup 5/2}-Newtonian equations of motion with relativistic corrections of all orders up to and including radiation reaction. Using the method of close orbital elements from celestial mechanics, the author evolves the orbits to separations of r {approx} 2 m, where m is the total mass, at which point the (post){sup 5/2}-Newtonian approximation breaks down. With the orbits as input, he calculates the gravitational waveform and luminosity using a post-Newtonian formalism of Wagoner and Will. Results are obtained for systems containing various combinations of compact objects, for various values of the mass ratio m{sub 1}/m{sub 2}, and forg various initial values of the orbital eccentricity.

  10. Thermal plasma synthesis of coated iron cobalt-iron cobalt vanadium nanoparticles as precursors for compacted nanocrystalline bulk magnets

    NASA Astrophysics Data System (ADS)

    Turgut, Zafer

    2000-12-01

    High temperature power applications such as starter and generator components of the aircraft engines require soft magnetic materials with optimum magnetic properties. Thus creep resistance and yield strength become important material properties due to the high temperatures and high rotational forces. FeCo based alloys are the only material that can meet desired magnetic properties but they exhibit poor creep resistance at temperatures up to 775 K. Eddy current losses, which are strong dependent on the materials' volume resistivity, are also one of the main concerns designing the aforementioned devices. Current technology utilizes stacks of ˜150 mum thick FeCo alloy laminates and limitations on dimensions arising from the eddy currents and skin depth issues. It is a well known fact that any improvement in mechanical properties through a secondary phase hardening will result in poor magnetic properties due to the domain wall pinning effect of the secondary phase. Engineering of fiber re-enforced structures to improve the mechanical properties also is not feasible due to the dimensions of the material. This indicates that any improvement on mechanical properties will interfere with the magnetic performance of the system. Coated nanoparticles eventually compacted in a bulk form, may offer a solution to poor mechanical properties thus magnetic properties can be further improved, i.e. lower coercivities and higher permeabilities, by tailoring the grain sizes to be smaller than the magnetic exchange length, Lex . Presence of a highly resistive coating phase can also reduce the eddy current losses and ease the limitations on the materials thickness. Oxide and carbon coated FeCo and FeCoV nanoparticles were synthesized through thermal plasma processing as precursors for the compacted bulk magnets. Their densification characteristics as well as the magnetic, structural and microstructural properties were studied before and after compaction. A hot isostatic pressing (HIP

  11. The neutron star in HESS J1731-347: Central compact objects as laboratories to study the equation of state of superdense matter

    NASA Astrophysics Data System (ADS)

    Klochkov, D.; Suleimanov, V.; Pühlhofer, G.; Yakovlev, D. G.; Santangelo, A.; Werner, K.

    2015-01-01

    Context. Central compact objects (CCOs) in supernova remnants are isolated thermally emitting neutron stars (NSs). They are most probably characterized by a magnetic field strength that is roughly two orders of magnitude lower than that of most of the radio and accreting pulsars. The thermal emission of CCOs can be modeled to obtain constraints on the physical parameters of the star such as its mass, radius, effective temperature, and chemical composition. Aims: The CCO in HESS J1731-347 is one of the brightest objects in this class. Starting from 2007, it was observed several times with different X-ray satellites. Here we present our analysis of two new XMM-Newton observations of the source performed in 2013 which increase the total exposure time of the data available for spectral analysis by a factor of about five compared to the analyses presented before. Methods: We use our numerical spectral models for carbon and hydrogen atmospheres to fit the spectrum of the CCO. From our fits, we derive constraints on the physical parameters of the emitting star such as its mass, radius, distance, and effective temperature. We also use the new data to derive new upper limits on the source pulsations and to confirm the absence of a long-term flux and spectral variability. Results: The analysis shows that atmosphere models are clearly preferred by the fit over the blackbody spectral function. Under the assumption that the X-ray emission is uniformly produced by the entire star surface (supported by the lack of pulsations), hydrogen atmosphere models lead to uncomfortably large distances of the CCO, above 7-8 kpc. On the other hand, the carbon atmosphere model formally excludes distances above 5-6 kpc and is compatible with the source located in the Scutum-Crux (~3 kpc) or Norma-Cygnus (~4.5 kpc) Galactic spiral arm. We provide and discuss the corresponding confidence contours in the NS mass-radius plane. The measured effective temperature indicates that the NS is

  12. Ceramic powder compaction

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Mahoney, F.M.

    1995-12-31

    With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

  13. mJIVE-20: A survey for compact mJy radio objects with the very long baseline array

    SciTech Connect

    Deller, A. T.; Middelberg, E.

    2014-01-01

    We present the description and early results of the mJy Imaging VLBA Exploration at 20 cm (mJIVE-20). mJIVE-20 is a large project on the Very Long Baseline Array which is systematically inspecting a large sample of mJy radio sources, pre-selected from the Faint Images of the Radio Sky at Twenty cm (FIRST) survey made with the Very Large Array, to identify any compact emission that may be present. The survey is being undertaken using filler time on the VLBA, which utilizes short segments scheduled in bad weather and/or with a reduced number of antennas, during which no highly rated science projects can be scheduled. The newly available multifield capability of the VLBA makes it possible for us to inspect of the order of 100 sources per hour of observing time with a 6.75σ detection sensitivity of approximately 1 mJy beam{sup –1}. The results of the mJIVE-20 survey are made publicly available as soon as the data are calibrated. After 18 months of observing, over 20,000 FIRST sources have been inspected, with 4336 very long baseline interferometry detections. These initial results suggest that within the range 1-200 mJy, fainter sources are somewhat more likely to be dominated by a very compact component than brighter sources. Over half of all arcsecond-scale mJy radio sources contain a compact component, although the fraction of sources that are dominated by milliarcsecond scale structure (where the majority of the arcsecond scale flux is recovered in the mJIVE-20 image) is smaller at around 30%-35%, increasing toward lower flux densities. Significant differences are seen depending on the optical classification of the source. Radio sources with a stellar/point-like counterpart in the Sloan Digital Sky Survey (SDSS) are more likely to be detected overall, but this detection likelihood appears to be independent of the arcsecond-scale radio flux density. The trend toward higher radio compactness for fainter sources is confined to sources that are not detected in SDSS

  14. Numerical investigations on a compact magnetic fusion device for studying the effect of external applied magnetic field oscillations on the nuclear burning efficiency of D-T and p-11B fuels

    NASA Astrophysics Data System (ADS)

    Moustaizis, S. D.; Lalousis, P.; Hora, H.; Larour, J.; Auvray, P.; Balcou, P.; Ducret, J.-E.; Martin, P.

    2015-05-01

    The burning process of high density (about 1018cm-3), high temperature (tens to hundreds of keV) plasma trapped by a high mirror-like magnetic field in a Compact Magnetic Fusion (CMF) device is numerically investigated.. The initial high density and high temperature plasma in the CMF device is produced by ultrashort high intensity laser beam interaction with clusters or thin foils, and two fuels, D-T and p-11B are studied. The spatio-temporal evolution of D-T and p-11B plasmas, the production of alphas, the generated electric fields and the high external applied magnetic field are described by a 1-D multifluid code. The initial values for the plasma densities, temperatures and external applied magnetic field (about 100 T) correspond to high β plasmas. The main objectives of the numerical simulations are: to study the plasma trapping, the neutron and alpha production for both fuels, and compare the effect of the external applied magnetic field on the nuclear burning efficiency for the two fuels.. The comparisons and the advantages for each fuel will be presented. The proposed CMF device and the potential operation of the device within the ELI-NP pillar will be discussed.

  15. Interaction between solar wind and mini-magnetosphere of magnetized objects

    NASA Astrophysics Data System (ADS)

    Nakamura, M.

    2009-12-01

    Interaction between the solar wind and the mini-magnetosphere of dipolar magnetized objects is investigated by a three-dimensional hybrid simulation, which treats the ions as kinetic super particles via particle-in-cell method and the electrons as a massless fluid. The study is important for not only understanding of the physical interaction processes for magnetized asteroids but also evaluation of the magnetic sail propulsion that uses an artificial dipole magnetic field to deflect the solar wind. A physical parameter characterizing the magnetosphere is a distance ahead of the magnetized object where the magnetic field pressure balances the solar wind ram pressure. If the distance is much smaller than the ion Larmor radius, the interaction is very weak and the solar wind is hardly deflected. On the other hand, if the distance becomes much larger, it will approach an earth-like magnetosphere. When the distance is the order of the ion Larmor radius, the ion kinetic effects become much important for the formation and structure of the mini-magnetosphere. We develop a three-dimensional hybrid simulation code and investigate the formation and structure of the mini-magnetosphere for the various magnitudes and inclinations of the magnetic dipole and its influence of the momentum transfer from the solar wind to the magnetized object.

  16. A compact model for magnetic tunnel junction (MTJ) switched by thermally assisted Spin transfer torque (TAS + STT)

    NASA Astrophysics Data System (ADS)

    Zhao, Weisheng; Duval, Julien; Klein, Jacques-Olivier; Chappert, Claude

    2011-12-01

    Thermally assisted spin transfer torque [TAS + STT] is a new switching approach for magnetic tunnel junction [MTJ] nanopillars that represents the best trade-off between data reliability, power efficiency and density. In this paper, we present a compact model for MTJ switched by this approach, which integrates a number of physical models such as temperature evaluation and STT dynamic switching models. Many experimental parameters are included directly to improve the simulation accuracy. It is programmed in the Verilog-A language and compatible with the standard IC CAD tools, providing an easy parameter configuration interface and allowing high-speed co-simulation of hybrid MTJ/CMOS circuits.

  17. Discovery of a 105-ms X-ray Pulsar in Kesteven-79: On the Nature of Compact Central Objects in Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Gotthelf, E. V.; Halpern, J. P.; Seward, F. D.

    2005-01-01

    We report the discovery of 105-ms X-ray pulsations from the compact central object (CCO) in the supernova remnant \\snr\\ using data acquired with the {\\it Newton X-Ray Multi-Mirror Mission). Using two observations of the pulsar taken 6-days apart we derive an upper limit on its spin-down rate of $\\dot P < 9 \\times 10"{-14}$-s-${-l)$,a nd find no evidence for binary orbital motion. The implied energy loss rate is $\\dot E < 3 \\times 10A{36)$-ergs-s$A{-1)$, polar magnetic field strength is $B-{\\rm p) < 3 \\times 10A{12)$-G, and spin-down age is $\\tau > 18.5$-kyr. The latter exceeds the remnant's estimated age, suggesting that the pulsar was born spinning near its current period. The X-ray spectrum of \\psr\\ is best characterized as a blackbody of temperature $kT {BB) =, 0.43\\pm0.02$ keV, radius $R-{BB) \\approx 1.3$-km, and $I{\\rm bol) = 5.2 \\times 10A{33)$ ergs-sSA{-1)$ at $d = 7.1$-kpc. The sinusoidal light curve is modulated with a pulsed fraction of $>45\\%$, suggestive of a small hot spot on the surface of the rotating neutron star. The lack of a discernible pulsar wind nebula is consistent with an interpretation of \\psr\\ as a rotation-powered pulsar whose spin-down luminosity falls below the empirical threshold for generating bright wind nebulae, $\\dot E-{\\rm c) = 4 \\times 10A{36)$-ergs-sSA{-I)$. The age discrepancy suggests that its $\\dot E$ has always been below $\\dot E c$, perhaps a distinguishing property of the CCOs. Alternatively, the X-ray spectrum of \\psr\\ suggests a low-luminosity AXP, but the weak inferred $B-{\\rm p)$ field is incompatible with a magnetar theory of its X-ray luminosity. The ordinary spin parameters discovered from \\psr\\ highlight the inability of existing theories to explain the high luminosities and temperatures of CCO thermal X-ray spectra.

  18. Compact X-band high power load using magnetic stainless steel

    SciTech Connect

    Tantawi, S.G. |; Vlieks, A.E.

    1995-05-01

    We present design and experimental results of a high power X-band load. The load is formed as a disk-loaded waveguide structure using lossy, Type 430 stainless steel. The design parameters have been optimized using the recently developed mode-matching code MLEGO. The load has been designed for compactness while maintaining a band width greater than 300 MHz.

  19. Low-cost, compact, cooled photomultiplier assembly for use in magnetic fields up to 1400 Gauss

    NASA Technical Reports Server (NTRS)

    Patch, R. W.; Tashjian, R. A.; Jentner, T. A.

    1975-01-01

    Use of vortex tube for cooling and concentric shielding have produced smaller and more compact unit than was previously available. Future uses of device could include installation in gas chromatographs and mass spectrometers. Additional uses would include measurements and controls in magnetohydrodynamic power generators and fusion reactors.

  20. Bulk CoNiFe-SiB Amorphous and Nanostructured Alloys Produced by Plasma Spray Deposition and Dynamic Compaction: Formation of Soft Magnetic Properties

    NASA Astrophysics Data System (ADS)

    Denisova, Elena; Kuzovnikova, Ludmila; Iskhakov, Rauf; Kuzovnikov, Aleksandr; Lepeshev, Anatoly; Nemtsev, Ivan; Saunin, Viktor; Telegin, Sergey; Bondarenko, Galina; Mal`tsev, Vadim

    The bulk nanostructured Co58Ni10Fe5B16Si11 alloys were prepared by dynamic compaction and plasma spray deposition techniques. The investigation of structure and magnetic properties of bulk samples was carried out by X-ray diffraction, electron microscopy and correlation magnetometry. The bulk samples produced by both methods can be characterized as a heterophase system. The highest value of permeability 20 · 103 for plasma spraying coating is achieved when volume fraction of nanocrystalline phase with Curie temperature Tc ∼ 640 K is increased to 30%. The magnetic characteristics, such as the saturation magnetization, the Bloch constant, the local magnetic anisotropy field, the ferromagnetic resonance linewidth, and the coercivity remain unchanged after both compaction techniques. It was shown that the plasma spraying method allows to obtain bulk magnetically soft materials with magnetic parameters that are not inferior to the characteristics of a thermally treated rapidly quenched ribbon with the same composition.

  1. OBSERVATIONAL UPPER BOUND ON THE COSMIC ABUNDANCES OF NEGATIVE-MASS COMPACT OBJECTS AND ELLIS WORMHOLES FROM THE SLOAN DIGITAL SKY SURVEY QUASAR LENS SEARCH

    SciTech Connect

    Takahashi, Ryuichi; Asada, Hideki

    2013-05-01

    The latest result in the Sloan Digital Sky Survey Quasar Lens Search (SQLS) has set the first cosmological constraints on negative-mass compact objects and Ellis wormholes. There are no multiple images lensed by the above two exotic objects for {approx}50, 000 distant quasars in the SQLS data. Therefore, an upper bound is put on the cosmic abundances of these lenses. The number density of negative-mass compact objects is n < 10{sup -8}(10{sup -4}) h {sup 3} Mpc{sup -3} at the mass scale |M| > 10{sup 15}(10{sup 12}) M{sub Sun }, which corresponds to the cosmological density parameter |{Omega}| < 10{sup -4} at the galaxy and cluster mass range |M| = 10{sup 12-15} M{sub Sun }. The number density of the Ellis wormhole is n < 10{sup -4} h {sup 3} Mpc{sup -3} for a range of the throat radius a = 10-10{sup 4} pc, which is much smaller than the Einstein ring radius.

  2. Dark matter mini-halo around the compact objects: the formation, evolution and possible contribution to the cosmic ray electrons/positrons

    SciTech Connect

    Yang, Rui-Zhi; Fan, Yi-Zhong; Chang, Jin; Waldman, Roni E-mail: yzfan@pmo.ac.cn E-mail: chang@pmo.ac.cn

    2012-01-01

    Dark matter particles may be captured by a star and then thermalized in the star's core. At the end of its life a massive star collapses suddenly and a compact object is formed. The dark matter particles redistribute accordingly. In the inelastic dark matter model, an extended dense dark matter mini-halo surrounding the neutron star may be formed. Such mini-halos may be common in the Galaxy. The electron/positron flux resulting in the annihilation of dark matter particles, however, is unable to give rise to observable signal unless a nascent mini-halo is within a distance ∼ a few 0.1 pc from the Earth.

  3. Complex Nano-objects Displaying Both Magnetic and Catalytic Properties: A Proof of Concept for Magnetically Induced Heterogeneous Catalysis.

    PubMed

    Meffre, Anca; Mehdaoui, Boubker; Connord, Vincent; Carrey, Julian; Fazzini, Pier Francesco; Lachaize, Sébastien; Respaud, Marc; Chaudret, Bruno

    2015-05-13

    Addition of Co2(Co)9 and Ru3(CO)12 on preformed monodisperse iron(0) nanoparticles (Fe(0) NPs) at 150 °C under H2 leads to monodisperse core-shell Fe@FeCo NPs and to a thin discontinuous Ru(0) layer supported on the initial Fe(0) NPs. The new complex NPs were studied by state-of-the-art transmission electron microscopy techniques as well as X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. These particles display large heating powers (SAR) when placed in an alternating magnetic field. The combination of magnetic and surface catalytic properties of these novel objects were used to demonstrate a new concept: the possibility of performing Fischer-Tropsch syntheses by heating the catalytic nanoparticles with an external alternating magnetic field. PMID:25867032

  4. Simple estimation of dipole source z-distance with compact magnetic gradiometer

    NASA Astrophysics Data System (ADS)

    Janošek, M.; Platil, A.; Vyhnánek, J.

    2016-03-01

    A compact magnetometer/gradiometer with combined homogeneous and gradient outputs facilitates precise measurement of both H and G values with good spatial and temporal coherence. By evaluating combination of both signals, it is possible to estimate distance to a dipole source with relatively small error and largely independent from precise knowledge of source strength, orientation and lateral displacement. The performance is limited primarily by ambient noise. With an AC-driven source, tool navigation or distance sensing is also possible.

  5. Simulation of an improved magnetic-electrostatic detector objective lens for LVSEM

    NASA Astrophysics Data System (ADS)

    Knell, G.; Plies, E.

    1999-05-01

    The simulations of the imaging properties of several magnetic-electrostatic detector objective lenses are presented. We have assumed that the magnetic circuit has a radially arranged pole-piece gap. By using this snorkel lens design the specimen is immersed in a strong magnetic field. The calculations show that the chromatic aberration coefficient, which essentially determines the resolution in low-voltage scanning electron microscopy, only decreases with increasing immersion ratio if the radius of the inner pole piece is not too small. Furthermore we determined the collection efficiency of secondary electrons for a lens variant which is optimized with respect to primary electron optics.

  6. Effect of ball-milling surfactants on the interface chemistry in hot-compacted SmCo5 magnets

    SciTech Connect

    Li, WF; Sepehri-Amin, H; Zheng, LY; Cui, BZ; Gabay, AM; Hono, K; Huang, WJ; Ni, C; Hadjipanayis, GC

    2012-11-01

    Anisotropic SmCo5 nanoflakes prepared by high-energy ball-milling with surfactants have great potential in applications for high-performance nanocomposite magnets. For such "nanocomposite" applications, the surface structure and chemistry of nanoflakes are crucial for achieving high coercivity. In this study, hot-pressed samples from anisotropic SmCo5 nanoflakes, ball-milled with different surfactants, oleic acid (OA) and oleylamine (OY), were investigated. Interface layers between the SmCo5 nanoflakes were found to consist of samarium oxides and a soft magnetic Co phase. These surface layers contribute to the degradation of hard magnetic performance, which is confirmed by scanning transmission electron microscopy-energy dispersive X-ray spectroscopy analysis of the cross-section of a single flake ball-milled with OA. Samples milled with OY show a much thinner interface layer in compacted samples, which means that the surface degradation during ball-milling with OY is much less than that with OA. The results show clearly that the choice of proper surfactant and the control of processing parameters are the key factors for improving the surface condition of the nanoflakes and the resulting hard magnetic properties. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  7. A compact small-beam XRF instrument for in-situ analysis of objects of historical and/or artistic value

    NASA Astrophysics Data System (ADS)

    Vittiglio, G.; Janssens, K.; Vekemans, B.; Adams, F.; Oost, A.

    1999-11-01

    The analytical characteristics, possibilities and limitations of a compact and easily transportable small-beam XRF instrument are described. The instrument consists of a compact, mini-focus Mo X-ray tube that is collimated to produce a sub-mm beam and a peltier-cooled PIN diode detector. Relative MDLs in highly scattering matrices are situated in the 10-100-ppm range; for metallic matrices featuring strong matrix lines, the MDLs of the instrument are approximately a factor 2 higher. Since only a small irradiation area is required, a simple micro-polishing technique that may be performed in situ in combination with the measurements is shown to be effective for the determination of the bulk composition of corroded bronze objects. As an example, a series of Egyptian bronze objects date from XXII nd Egyptian Dynasty (ca. 1090 BC) to the Roman era (30 BC to 640 AD) was analyzed in order to contribute to the very limited database on Cu-alloy compositions from this period.

  8. Alternating-gradient canted cosine theta superconducting magnets for future compact proton gantries

    NASA Astrophysics Data System (ADS)

    Wan, Weishi; Brouwer, Lucas; Caspi, Shlomo; Prestemon, Soren; Gerbershagen, Alexander; Schippers, Jacobus Maarten; Robin, David

    2015-10-01

    We present a design of superconducting magnets, optimized for application in a gantry for proton therapy. We have introduced a new magnet design concept, called an alternating-gradient canted cosine theta (AG-CCT) concept, which is compatible with an achromatic layout. This layout allows a large momentum acceptance. The 15 cm radius of the bore aperture enables the application of pencil beam scanning in front of the SC-magnet. The optical and dynamic performance of a gantry based on these magnets has been analyzed using the fields derived (via Biot-Savart law) from the actual windings of the AG-CCT combined with the full equations of motion. The results show that with appropriate higher order correction, a large 3D volume can be rapidly scanned with little beam shape distortion. A very big advantage is that all this can be done while keeping the AG-CCT fields fixed. This reduces the need for fast field ramping of the superconducting magnets between the successive beam energies used for the scanning in depth and it is important for medical application since this reduces the technical risk (e.g., a quench) associated with fast field changes in superconducting magnets. For proton gantries the corresponding superconducting magnet system holds promise of dramatic reduction in weight. For heavier ion gantries there may furthermore be a significant reduction in size.

  9. Analyze and experiment on AC magnetic field's effect to fiber optic gyroscopes in compact stabilization control systems

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Mao, Yao; Tian, Jing; Li, Zhijun

    2015-10-01

    Fiber optic gyroscopes (FOG) are getting more and more attention in areas such as stabilization control systems as they are all solid state and have a wide bandwidth. In stabilization systems that require wide bandwidth control, motors are usually used as actuating mechanism for active disturbance restrain. Voice coil motors (VCMs) are usually used in compact stabilization systems that require large torque and fast response. However, AC magnetic field, which can affect the output of FOG due to Faraday effect, will be generated during operation of VCMs. The frequency range affected by the AC magnetic field to the FOG's output is the same as VCMs drive signal frequency range, which is also exactly the stabilization system's working range. Therefore the effect of the AC magnetic field to FOGs must be evaluated to verify the feasibility of a stable system design that uses both FOGs and VCMs. In this article, the basic structure and operating principle of stabilization system is introduced. The influence of AC magnetic field to FOG is theoretically analyzed. The magnetic field generated by VCMs is numerically simulated based on the theory deduction of the magnetic field near energized wires. To verify the influence of the VCM generated magnetic field to the FOGs in practical designs, a simplified random fiber coil model is built for it's hard to accurately test the exact polarize axis's twisting rate in a fiber coil. The influence to the FOG's output of different random coil model is simulated and the result shows a same trend that the influence of the VCM's magnetic field to the FOG is reduced as the distance between the VCM and the FOG increasing. The influence of a VCM to a FOG with the same parameters is experimentally tested. In the Fourier transformed FOG data the same frequency point as the VCM drive signal frequency can be read. The result fit simulated result that as the distance increases, the influence decreases. The amplitude of the frequency point is just

  10. Thermodynamics of static black objects in D dimensional Einstein-Gauss-Bonnet gravity with D-4 compact dimensions

    NASA Astrophysics Data System (ADS)

    Sahabandu, C.; Suranyi, P.; Vaz, C.; Wijewardhana, L. C.

    2006-02-01

    We investigate the thermodynamics of static black objects such as black holes, black strings and their generalizations to D dimensions (“black branes”) in a gravitational theory containing the four-dimensional Gauss-Bonnet term in the action, with D-4 dimensions compactified torus. The entropies of black holes and black branes are compared to obtain information on the stability of these objects and to find their phase diagrams. We demonstrate the existence of a critical mass, which depends on the scale of the compactified dimensions, below which the black hole entropy dominates over the entropy of the black membrane.

  11. First Report on Accomplishments in Achieving Other Project Objectives. Magnet Assistance Program Performance Report.

    ERIC Educational Resources Information Center

    Charlotte-Mecklenburg Public Schools, Charlotte, NC.

    The 1993-94 school year marked the first year of the federally-assisted magnet program implemented by Charlotte-Mecklenberg (North Carolina) Schools (CMS). This paper presents the program's goals, the measurable objectives developed to meet the goals, and first-year outcomes. The goals were to reduce, eliminate, or prevent minority group isolation…

  12. Circular Samples as Objects for Magnetic Resonance Imaging - Mathematical Simulation, Experimental Results

    NASA Astrophysics Data System (ADS)

    Frollo, Ivan; Krafčík, Andrej; Andris, Peter; Přibil, Jiří; Dermek, Tomáš

    2015-12-01

    Circular samples are the frequent objects of "in-vitro" investigation using imaging method based on magnetic resonance principles. The goal of our investigation is imaging of thin planar layers without using the slide selection procedure, thus only 2D imaging or imaging of selected layers of samples in circular vessels, eppendorf tubes,.. compulsorily using procedure "slide selection". In spite of that the standard imaging methods was used, some specificity arise when mathematical modeling of these procedure is introduced. In the paper several mathematical models were presented that were compared with real experimental results. Circular magnetic samples were placed into the homogenous magnetic field of a low field imager based on nuclear magnetic resonance. For experimental verification an MRI 0.178 Tesla ESAOTE Opera imager was used.

  13. Experimental investigation in plasma relaxation by using a compact coaxial magnetized plasma gun in a background plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott

    2012-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation process being conducted in the HELCAT device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5 - 10kV. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities 1.2Cs and densities 10e20 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter lambda determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  14. Decoherence-governed magnetic-moment dynamics of supported atomic objects

    NASA Astrophysics Data System (ADS)

    Gauyacq, Jean-Pierre; Lorente, Nicolás

    2015-11-01

    Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system’s size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the μK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching.

  15. Decoherence-governed magnetic-moment dynamics of supported atomic objects.

    PubMed

    Gauyacq, Jean-Pierre; Lorente, Nicolás

    2015-11-18

    Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system's size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the μK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching. PMID:26471260

  16. Microwave Heating and Pre-sintering of Copper Powder Metal Compacts in Separated Electric and Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Martin, Kelly; Johnson, Earnie; Ma, Junkun; Miskovsky, Nicholas; Weisel, Gary; Weiss, Brock; Zimmerman, Darin

    2006-03-01

    We present results of microwave heating and pre-sintering of pure copper metal powder compacts. Using a 2.45GHz, WR284 microwave system operating in TE102 single mode resonance, we have systematically studied the microwave heating and pre-sintering behavior of various copper powder metal compacts as a function of particle size and green density. Cylindrical samples (0.25in by 0.25in) were positioned in either the magnetic-- or electric--field antinode, allowing the study of the separate effects of the two fields. The results show significant differences in heating rates and sample microstructure (SEM) even when average sample temperatures are below half the melting point of bulk copper. Numerical simulations of the absorption and heating have been developed to check the consistency of the experimental results. We acknowledge the additional work of undergraduate students John Diehl, John Rea, Charles Smith, and Devin Spratt, who assisted in the setup of experimental apparatus, sample preparation, and data acquisition.

  17. Excitation of stable Alfven eigenmodes by application of alternating magnetic field perturbations in the Compact Helical System

    SciTech Connect

    Ito, T.; Toi, K.; Isobe, M.; Nagaoka, K.; Takeuchi, M.; Akiyama, T.; Matsuoka, K.; Minami, T.; Nishimura, S.; Okamura, S.; Shimizu, A.; Suzuki, C.; Yoshimura, Y.; Takahashi, C.; Matsunaga, G.

    2009-09-15

    Stable toroidicity-induced Alfven eigenmodes (TAEs) with low toroidal mode number (n=1 and n=2) were excited by application of alternating magnetic field perturbations generated with a set of electrodes inserted into the edge region of neutral beam injection heated plasmas on the Compact Helical System [K. Nishimura, K. Matsuoka, M. Fujiwara et al., Fusion Technol. 17, 86 (1990)]. The gap locations of TAEs excited by the electrodes are in the plasma peripheral region of {rho}>0.7 ({rho} is the normalized minor radius) where energetic ion drive is negligibly small, while some AEs are excited by energetic ions in the plasma core region of {rho}<0.4. The damping rate of these stable TAEs derived from plasma responses to applied perturbations is fairly large, that is, {approx}9% to {approx}12% of the angular eigenfrequency. This large damping rate is thought to be dominantly caused by continuum damping and radiative damping.

  18. First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-LAT Observations of the Compact Symmetric Object PKS 1718-649

    NASA Astrophysics Data System (ADS)

    Migliori, G.; Siemiginowska, A.; Sobolewska, M.; Loh, A.; Corbel, S.; Ostorero, L.; Stawarz, Ł.

    2016-04-01

    We report the γ-ray detection of a young radio galaxy, PKS 1718-649, belonging to the class of compact symmetric objects (CSOs), with the Large Area Telescope (LAT) on board the Fermi satellite. The third Fermi Gamma-ray LAT catalog (3FGL) includes an unassociated γ-ray source, 3FGL J1728.0-6446, located close to PKS 1718-649. Using the latest Pass 8 calibration, we confirm that the best-fit 1σ position of the γ-ray source is compatible with the radio location of PKS 1718-649. Cross-matching of the γ-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718-649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS ˜ 36 (>5σ) with a best-fit photon spectral index Γ = 2.9 ± 0.3 and a 0.1-100 GeV photon flux density F 0.1-100 GeV = (11.5 ± 0.3) × 10-9 ph cm-2 s-1. We argue that the linear size (˜2 pc), the kinematic age (˜100 years), and the source distance (z = 0.014) make PKS 1718-649 an ideal candidate for γ-ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverse-Compton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in γ-rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters and yields a unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy.

  19. First evidence of detecting surface nuclear magnetic resonance signals using a compact B-field sensor

    NASA Astrophysics Data System (ADS)

    Davis, Aaron C.; Dlugosch, Raphael; Queitsch, Matthias; Macnae, James C.; Stolz, Ronny; Müller-Petke, Mike

    2014-06-01

    The noninvasive detection and characterization of subsurface aquifer structures demands geophysical techniques. Surface nuclear magnetic resonance (SNMR) is the only technique that is directly sensitive to hydrogen protons and, therefore, allows for unambiguous detection of subsurface water. Traditionally, SNMR utilizes large surface coils for both transmitting excitation pulses and recording the groundwater response. Recorded data are thus a voltage induced by the time derivative of the secondary magnetic field. For the first time, we demonstrate that the secondary magnetic field in a SNMR experiment can be directly detected using a superconducting quantum interference device magnetometer. Conducting measurements at a test site in Germany, we demonstrate not only the ability to detect SNMR signals on the order of femtoTesla but also we are able to satisfy the observed data by inverse modeling. This is expected to open up completely new applications for this exciting technology.

  20. Generation of strong pulsed magnetic fields using a compact, short pulse generator

    NASA Astrophysics Data System (ADS)

    Yanuka, D.; Efimov, S.; Nitishinskiy, M.; Rososhek, A.; Krasik, Ya. E.

    2016-04-01

    The generation of strong magnetic fields (˜50 T) using single- or multi-turn coils immersed in water was studied. A pulse generator with stored energy of ˜3.6 kJ, discharge current amplitude of ˜220 kA, and rise time of ˜1.5 μs was used in these experiments. Using the advantage of water that it has a large Verdet constant, the magnetic field was measured using the non-disturbing method of Faraday rotation of a polarized collimated laser beam. This approach does not require the use of magnetic probes, which are sensitive to electromagnetic noise and damaged in each shot. It also avoids the possible formation of plasma by either a flashover along the conductor or gas breakdown inside the coil caused by an induced electric field. In addition, it was shown that this approach can be used successfully to investigate the interesting phenomenon of magnetic field enhanced diffusion into a conductor.

  1. Approaching the Post-Newtonian Regime with Numerical Relativity: A Compact-Object Binary Simulation Spanning 350 Gravitational-Wave Cycles.

    PubMed

    Szilágyi, Béla; Blackman, Jonathan; Buonanno, Alessandra; Taracchini, Andrea; Pfeiffer, Harald P; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Pan, Yi

    2015-07-17

    We present the first numerical-relativity simulation of a compact-object binary whose gravitational waveform is long enough to cover the entire frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, for mass ratio 7 and total mass as low as 45.5M_{⊙}. We find that effective-one-body models, either uncalibrated or calibrated against substantially shorter numerical-relativity waveforms at smaller mass ratios, reproduce our new waveform remarkably well, with a negligible loss in detection rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and existing calibrated phenomenological inspiral-merger-ringdown waveforms display greater disagreement with our new simulation. The disagreement varies substantially depending on the specific post-Newtonian approximant used. PMID:26230780

  2. NuSTAR and XMM-Newton Observations of 1E1743.1-2843: Indications of a Neutron Star LMXB Nature of the Compact Object

    NASA Astrophysics Data System (ADS)

    Lotti, Simone; Natalucci, Lorenzo; Mori, Kaya; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Hong, Jaesub; Krivonos, Roman A.; Rahoui, Farid; Stern, Daniel; Tomsick, John A.; Zhang, Shuo; Zhang, William W.

    2016-05-01

    We report on the results of NuSTAR and XMM-Newton observations of the persistent X-ray source 1E1743.1-2843, located in the Galactic Center region. The source was observed between 2012 September and October by NuSTAR and XMM-Newton, providing almost simultaneous observations in the hard and soft X-ray bands. The high X-ray luminosity points to the presence of an accreting compact object. We analyze the possibilities of this accreting compact object being either a neutron star (NS) or a black hole, and conclude that the joint XMM-Newton and NuSTAR spectrum from 0.3 to 40 keV fits a blackbody spectrum with {kT}∼ 1.8 {keV} emitted from a hot spot or an equatorial strip on an NS surface. This spectrum is thermally Comptonized by electrons with {{kT}}e∼ 4.6 {keV}. Accepting this NS hypothesis, we probe the low-mass X-ray binary (LMXB) or high-mass X-ray binary (HMXB) nature of the source. While the lack of Type-I bursts can be explained in the LMXB scenario, the absence of pulsations in the 2 mHz–49 Hz frequency range, the lack of eclipses and of an IR companion, and the lack of a {K}α line from neutral or moderately ionized iron strongly disfavor interpreting this source as a HMXB. We therefore conclude that 1E1743.1-2843 is most likely an NS-LMXB located beyond the Galactic Center. There is weak statistical evidence for a soft X-ray excess which may indicate thermal emission from an accretion disk. However, the disk normalization remains unconstrained due to the high hydrogen column density ({N}{{H}}∼ 1.6× {10}23 {{cm}}-2).

  3. Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device.

    PubMed

    Matsumoto, T; Sekiguchi, J; Asai, T; Gota, H; Garate, E; Allfrey, I; Valentine, T; Morehouse, M; Roche, T; Kinley, J; Aefsky, S; Cordero, M; Waggoner, W; Binderbauer, M; Tajima, T

    2016-05-01

    A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10(21) m(-3), ∼40 eV, and 0.5-1.0 × 10(19), respectively. PMID:27250428

  4. Application of a compact magnetic resonance imaging system for toxicologic pathology: evaluation of lithium-pilocarpine-induced rat brain lesions.

    PubMed

    Taketa, Yoshikazu; Shiotani, Motohiro; Tsuru, Yoshiharu; Kotani, Sadaharu; Osada, Yoshihide; Fukushima, Tatsuto; Inomata, Akira; Hosokawa, Satoru

    2015-10-01

    Magnetic resonance imaging (MRI) is a useful noninvasive tool used to detect lesions in clinical and veterinary medicine. The present study evaluated the suitability of a new easy-to-use compact MRI platform (M2 permanent magnet system, Aspect Imaging, Shoham, Israel) for assisting with preclinical toxicologic pathology examination of lesions in the rat brain. In order to induce brain lesions, male Sprague-Dawley rats were treated once with lithium chloride (127 mg/kg, intraperitoneal [i.p.]) followed by pilocarpine (30 mg/kg, i.p.). One week after dosing, the perfused, fixed brains were collected, analyzed by the MRI system and examined histopathologically. MRI of the brain of treated rats revealed areas of high T1 and middle to low T2 signals, when compared with the controls, in the piriform cortex, lateral thalamic nucleus, posterior paraventricular thalamic nucleus and posterior hypothalamic nucleus of the cerebrum. The altered MRI signal areas were consistent with well-circumscribed foci of neuronal cell degeneration/necrosis accompanied by glial cell proliferation. The present data demonstrated that quick analysis of fixed organs by the MRI system can detect the presence and location of toxicologic lesions and provide useful temporal information for selection of appropriate sections for histopathologic examination before routine slide preparation, especially in complex and functionally heterogeneous organs such as the brain. PMID:26538811

  5. Application of a compact magnetic resonance imaging system for toxicologic pathology: evaluation of lithium-pilocarpine-induced rat brain lesions

    PubMed Central

    Taketa, Yoshikazu; Shiotani, Motohiro; Tsuru, Yoshiharu; Kotani, Sadaharu; Osada, Yoshihide; Fukushima, Tatsuto; Inomata, Akira; Hosokawa, Satoru

    2015-01-01

    Magnetic resonance imaging (MRI) is a useful noninvasive tool used to detect lesions in clinical and veterinary medicine. The present study evaluated the suitability of a new easy-to-use compact MRI platform (M2 permanent magnet system, Aspect Imaging, Shoham, Israel) for assisting with preclinical toxicologic pathology examination of lesions in the rat brain. In order to induce brain lesions, male Sprague-Dawley rats were treated once with lithium chloride (127 mg/kg, intraperitoneal [i.p.]) followed by pilocarpine (30 mg/kg, i.p.). One week after dosing, the perfused, fixed brains were collected, analyzed by the MRI system and examined histopathologically. MRI of the brain of treated rats revealed areas of high T1 and middle to low T2 signals, when compared with the controls, in the piriform cortex, lateral thalamic nucleus, posterior paraventricular thalamic nucleus and posterior hypothalamic nucleus of the cerebrum. The altered MRI signal areas were consistent with well-circumscribed foci of neuronal cell degeneration/necrosis accompanied by glial cell proliferation. The present data demonstrated that quick analysis of fixed organs by the MRI system can detect the presence and location of toxicologic lesions and provide useful temporal information for selection of appropriate sections for histopathologic examination before routine slide preparation, especially in complex and functionally heterogeneous organs such as the brain. PMID:26538811

  6. Method for locating a small magnetic object in the human body

    SciTech Connect

    Kaufman, L.; Williamson, S.J.; Ilmoniemi, R.J.; Weinberg, H.; Boyd, A.D.

    1988-02-29

    A piece of a thin acupuncture needle lodged under the right scapula of a patient could not be found in surgical procedures accompanied by studies of 30 standard x-ray images. To locate it, the authors mapped the magnetic-field component normal to a plane lying above the object, using a superconducting quantum interference device (SQUID). Assuming that the needle could be modeled as a magnetic dipole, the authors were able to infer its lateral position, depth, orientation, and magnetic moment. With this information, directed CT scans, high-resolution x-ray films, and the subsequent surgical removal of the needle proved that it could be located in the body with an accuracy of about three millimeters.

  7. Hall probe measurements of the poloidal magnetic field in Compact Toroidal Hybrid plasmas

    SciTech Connect

    Stevenson, B. A.; Knowlton, S. F.; Hartwell, G. J. Hanson, J. D.; Maurer, D. A.

    2014-09-15

    A linear array of 16 Hall effect sensors has been developed to directly measure the poloidal magnetic field inside the boundary of a non-axisymmetric hybrid torsatron/tokamak plasma. The array consists of miniature gallium arsenide Hall sensor elements mounted 8 mm apart on a narrow, rotatable printed circuit board inserted into a re-entrant stainless steel tube sheathed in boron nitride. The sensors are calibrated on the bench and in situ to provide accurate local measurements of the magnetic field to aid in reconstructing the equilibrium plasma current density profiles in fully three-dimensional plasmas. Calibrations show that the sensor sensitivities agree with the nominal manufacturers specifications of 1.46 V/T. Poloidal fields measured with the Hall sensor array are found to be within 5% of poloidal fields modeled with a Biot-Savart code.

  8. Compact and lightweight VLF/LF magnetic antenna with femtotesla noise level

    NASA Astrophysics Data System (ADS)

    Marusenkov, Andriy

    2016-04-01

    The measurements of the electromagnetic field in the frequency band 3-300 kHz are widely used for subsurface geophysical surveys, investigations of the various phenomena in the Earth-ionosphere cavity, in the ionosphere and in the magnetosphere, including those connected with seismic and lightning activity. The instrumental noise has to be as low as possible in order to reliably detect the weakest electromagnetic signals, which magnitude could be only a few femtoteslas. In order to decrease magnetic antenna noises the size and mass of the probe has to be increased. However, such approach could be hardly applied for development of mobile sensors. In this report the efforts to achieve the minimal possible noise level at the restricted weight and size of the magnetic antenna are presented. Applying the minimal mass criteria the noise level of the induction coil with a high permeability magnetic core, used as a probe, was optimized. The new pre-amplifier, based on the ultra low noise field effect transistor, was developed. The special attention was paid to the design of the electrostatic screen, which has to generate negligible magnetic noise. As a result, the 300 mm long, 25 mm diameter antenna has the noise level approximately 1 fT/sqrt(Hz) in the frequency band 50 - 200 kHz and <5 fT/sqrt(Hz) in the band 3 - 500 kHz. The mass of the antenna is equal to 0.27 kg for the weather protected version and 0.15 kg for the indoor version. The possibilities to achieve even lower noise level at the same size of the instrument will be also discussed.

  9. Depth limitations for in vivo magnetic nanoparticle detection with a compact handheld device

    NASA Astrophysics Data System (ADS)

    Visscher, Martijn; Waanders, Sebastiaan; Pouw, Joost; ten Haken, Bennie

    2015-04-01

    The increasing interest for local detection of magnetic nanoparticles (MNPs) during clinical interventions requires the development of suitable probes that unambiguously detect the MNPs at a depth of several centimeters in the body. The present study quantitatively evaluates the limitations of a conventional magnetometry method using a sinusoidal alternating field. This method is limited by the variability of the magnetic susceptibility of the surrounding diamagnetic tissue. Two different sensors are evaluated in a theoretical model of MNP detection in a tissue volume. For a coil that completely encloses the sample volume, the MNPs can be detected if the total mass contributing to the signal is larger than 4.1 ×10-7 times the tissue mass. For a handheld surface coil, intended to search for the MNPs in a larger tissue volume, an amount of 1 μg of iron oxide cannot be detected by sensors with a diameter larger than 15 mm. To detect a spot with MNPs at 5 cm depth in tissue, it should contain at least 325 μg iron oxide. Therefore, for high-sensitive clinical MNP detection in surgical interventions, techniques with increased specificity for the nonlinear magnetic properties of MNPs are indispensable.

  10. Formation of compact toroidal plasmas by magnetized coaxial plasma gun injection into an oblate flux conserver

    NASA Astrophysics Data System (ADS)

    Turner, W. C.; Goldenbaum, G. C.; Granneman, E. H. A.; Hartman, C. W.; Prono, D. S.; Taska, J.; Smith, A. C., Jr.

    1980-11-01

    Initial results are reported on the formation of compact toroidal plasmas in an oblate shaped metallic flux conserver. A schematic of the experimental apparatus is shown. The plasma injector is a coaxial plasma gun with solenoid coils wound on the inner and outer electrodes. The electrode length is 100 cm, the diameter of the inner (outer) electrode is 19.3 cm (32.4 cm). Deuterium gas is puffed into the region between electrodes by eight pulsed valves located on the outer electrode 50 cm from the end of the gun. The gun injects into a cylindrically symmetrical copper shell (wall thickness = 1.6 mm) which acts as a flux conserver for the time scale of experiments reported here. The copper shell consists of a transition cylinder, a cylindrical oblate pill box, and a downstream cylinder. The gap between the gun and transition cylinder is 6 cm. An axial array of coils outside the vacuum chamber can be used to establish an initial uniform bias field.

  11. Formation of compact toroidal plasmas by magnetized coaxial plasma gun injection into an oblate flux conserver

    SciTech Connect

    Turner, W.C.; Goldenbaum, G.C.; Granneman, E.H.A.; Hartman, C.W.; Prono, D.S.; Taska, J.; Smith, A.C. Jr.

    1980-11-04

    Initial results are reported on the formation of compact toroidal plasmas in an oblate shaped metallic flux conserver. A schematic of the experimental apparatus is shown. The plasma injector is a coaxial plasma gun with solenoid coils wound on the inner and outer electrodes. The electrode length is 100 cm, the diameter of the inner (outer) electrode is 19.3 cm (32.4 cm). Deuterium gas is puffed into the region between electrodes by eight pulsed valves located on the outer electrode 50 cm from the end of the gun. The gun injects into a cylindrically symmetrical copper shell (wall thickness = 1.6 mm) which acts as a flux conserver for the time scale of experiments reported here. The copper shell consists of a transition cylinder 30 cm long, 34 cm in diameter, a cylindrical oblate pill box 40 cm long, 75 cm in diameter and a downstream cylinder 30 cm long, 30 cm in diameter. The gap between the gun and transition cylinder is 6 cm. An axial array of coils outside the vacuum chamber can be used to establish an initial uniform bias field.

  12. Compact magnetograph

    NASA Technical Reports Server (NTRS)

    Title, A. M.; Gillespie, B. A.; Mosher, J. W.

    1982-01-01

    A compact magnetograph system based on solid Fabry-Perot interferometers as the spectral isolation elements was studied. The theory of operation of several Fabry-Perot systems, the suitability of various magnetic lines, signal levels expected for different modes of operation, and the optimal detector systems were investigated. The requirements that the lack of a polarization modulator placed upon the electronic signal chain was emphasized. The PLZT modulator was chosen as a satisfactory component with both high reliability and elatively low voltage requirements. Thermal control, line centering and velocity offset problems were solved by a Fabry-Perot configuration.

  13. A novel compact repetitive frequency voltage booster based on magnetic switches and Fitch generator

    NASA Astrophysics Data System (ADS)

    Ren, Hang; Ding, Weidong; Wu, Jiawei

    2012-07-01

    In this paper, a novel repetitive frequency voltage booster (named repetitive Fitch booster by the authors) based on magnetic switches and Fitch generators is proposed. The principle of operation is to charge capacitors in parallel when magnetic switches (MSs) are unsaturated and reverse voltage polarity of every other capacitor when MSs saturate. With the principle, circuit topology of a 4-stage repetitive Fitch booster (RFB) is presented. Simulation as well as experiment shows its feasibility in boosting voltage and compressing rise-time. In simulation, the input voltage of 100 V is boosted to 372 V, while test stand yields output voltage with frequency of 1 kHz, amplitude of 19 kV with each capacitor charged to about 5.6 kV, and rise-time compression from 7.3 μs to 700 ns. Meanwhile, calculations show that the 4-stage RFB effectively reduces core volume by about half, from 1093.5 cm3 to 585.2 cm3. Furthermore, design rules are proposed so that topologies of RFBs with stages other than four can be conveniently derived. As an example, an 8-stage RFB is proposed and verified with circuit simulation, which shows an output voltage of 759 V with the input voltage of 100 V.

  14. Progress Toward a Compact 0.05 K Magnet Refrigerator Operating from 10 K

    NASA Technical Reports Server (NTRS)

    Canavan, Edgar; Shirron, Peter; DiPirro, Micheal; Tuttle, James; Jackson, Michael; King, Todd; Numazawa, Takenori

    2003-01-01

    Much of the most interesting information regarding our universe is hidden in the sub-millimeter, infrared, and x-rays bands of the spectrum, to which our atmosphere is largely opaque. Thus, missions exploring these bands are a very important part of NASA s Space Science program. Coincidentally, the most sensitive detectors in these spectral regions operate at extremely low temperatures, typically 0.05 - 0.10 K. Generally these temperatures will be achieved using magnetic refrigerators, also know as Adiabatic Demagnetization Refrigerators, or ADRs. Current ADRs, such as the one used in the XRS-II instrument on the Astro-E2 satellite, use a single-stage to cool detectors from 1.3 K to 0.06 K. The ADR is designed so that it can absorb the heat on the detector stage for at least 24 hours before it must stop, warm up to the helium bath temperature (1.3 K), and dump the accumulated heat. Future detector arrays will be much larger and will have higher heat dissipation. Furthermore, future missions will use mechanical cryocoolers to provide upper stage cooling, but they can only reach 4 - 10 K. Trying to scale heavy (-15 kg) single stage ADRs up to the higher heat loads and higher heat rejection temperatures required leads to unacceptably large systems. The GSFC Cryogenics Branch has developed the Continuous ADR (CADR) to solve this problem. The CADR consists of a series of ADR stages that sequentially pass heat from the load up to the high temperature heat sink. The stage connected to the load remains at a constant temperature. The continuous stage effectively decouples detector operation from ADR operation, allowing the ADR stages to be cycled much more rapidly. Rapid cycling leads to higher cooling power density. The cascading, multistage arrangement allows the magnetic refrigerant of each stage to be optimized for its own temperature swing. In the past year, we have made good progress toward a 0.05 to 10K system. A four-stage system that operates from 4.2 K was

  15. Implementation of a compact magnetic electron energy spectrometer for intense relativistic electron beams. Interim report

    SciTech Connect

    Gregor, J.A.; Antoniades, J.A.

    1993-11-05

    A diagnostic used for measuring the energy of 1 to 5 MEV pulsed electron beams by means independent of the beam generating device is investigated. The method employed is capable of collecting the required data optically in a single pulse. The beam energy is measured using a magnetic electron spectrometer coupled with a scintillating material. Using a polaroid camera to collect data, the energy of electron beams from two field emission diode accelerators is measured. The first is a nominal 1 MEV, 16 kA, 25 ns FWHM electron beam and the second is a nominal 5 MEV, 20 kA, 50 ns FWHM electron beam. A detailed study of measurement accuracy and possible sources of error was accomplished. Energy, Relativistic, Electron beam. Electron, Spectrometer.

  16. Development of a compact, sealless, tripod supported, magnetically driven centrifugal blood pump.

    PubMed

    Yuhki, A; Nogawa, M; Takatani, S

    2000-06-01

    In this study, a tripod supported sealless centrifugal blood pump was designed and fabricated for implantable application using a specially designed DC brushless motor. The tripod structure consists of 3 ceramic balls mounted at the bottom surface of the impeller moving in a polyethylene groove incorporated at the bottom pump casing. The follower magnet inside the impeller is coupled to the driver magnet of the motor outside the bottom pump casing, thus allowing the impeller to slide-rotate in the polyethylene groove as the motor turns. The pump driver has a weight of 230 g and a diameter of 60 mm. The acrylic pump housing has a weight of 220 g with the priming volume of 25 ml. At the pump rpm of 1,000 to 2,200, the generated head pressure ranged from 30 to 150 mm Hg with the maximum system efficiency being 12%. When the prototype pump was used in the pulsatile mock loop to assist the ventricle from its apex to the aorta, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics of the motor current power spectral density, was computed to possibly detect the suction occurring inside the ventricle due to the prototype centrifugal pump. When the WDI was kept under the value of 0.20 by adjusting the motor rpm, it was successful in suppressing the suction due to the centrifugal pump in the ventricle. The prototype sealless, centrifugal pump together with the control method based on the motor current waveform analysis may offer an intermediate support of the failing left or right ventricle bridging to heart transplantation. PMID:10886073

  17. Effect of ball milling and dynamic compaction on magnetic properties of Al{sub 2}O{sub 3}/Co(P) composite particles

    SciTech Connect

    Denisova, E. A.; Kuzovnikova, L. A.; Iskhakov, R. S. Eremin, E. V.; Bukaemskiy, A. A.; Nemtsev, I. V.

    2014-05-07

    The evolution of the magnetic properties of composite Al{sub 2}O{sub 3}/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al{sub 2}O{sub 3} granules were coated with a Co{sub 95}P{sub 5} shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al{sub 2}O{sub 3} powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

  18. Recognition of compact astrophysical objects

    NASA Technical Reports Server (NTRS)

    Ogelman, H. (Editor); Rothschild, R. (Editor)

    1977-01-01

    NASA's Laboratory for High Energy Astrophysics and the Dept. of Physics and Astrophysics at the Univ. of Md. collaberated on a graduate level course with this title. This publication is an edited version of notes used as the course text. Topics include stellar evolution, pulsars, binary stars, X-ray signatures, gamma ray sources, and temporal analysis of X-ray data.

  19. Spectral shifts near compact objects

    NASA Astrophysics Data System (ADS)

    Lake, K.; Myra, E.

    1981-10-01

    It is shown that radiation emitted from material freely falling toward a black hole or neutron star cannot be blue shifted as recently claimed by Cohen and Struble (1980). The relativistic corrections to the classical apparent limb angle are given explicitly for spherical sources in collapse.

  20. GRAVITATIONALLY FOCUSED DARK MATTER AROUND COMPACT STARS

    SciTech Connect

    Bromley, Benjamin C.

    2011-12-01

    If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates may rise steeply enough toward the Galactic Center that self-annihilation may produce detectable {gamma}-ray emission. Here, we discuss the possibility that an annihilation signal arises near a compact object (e.g., neutron star or black hole) even when the density of dark matter in the neighborhood of the object is uniform. Gravitational focusing produces a local enhancement of density with a profile that falls off approximately as the inverse square-root of distance from the compact star. While geometric dilution may overwhelm the annihilation signal from this local enhancement, magnetic fields tied to the compact object can increase the signal's contrast relative to the background.

  1. Current Profile and Magnetic Structure Measurements through Tangential Soft X-Ray Imaging in Compact Tori

    SciTech Connect

    Fonck, Raymond J.

    2004-07-12

    This report describes the fabrication and tests of a tangentially imaging soft X-ray (SXR) camera diagnostic for fusion energy plasma research. It can be used for the determination of the current distribution in strongly shaped toroidal magnetically confined plasmas, such as those found in spherical tori or advanced tokamaks. It included the development of both an appropriate imaging SXR camera and image analysis techniques necessary to deduce the plasma shape and current distribution. The basic camera concept consists of a tangentially viewing pinhole imaging system with thin-film SXR filters, a scintillator screen to provide SXR to visible conversion, a fast shuttering system, and an sensitive visible camera imaging device. The analysis approach consists of integrating the 2-D SXR image data into a Grad-Shafranov toroidal equilibrium solver code to provide strong constraints on the deduced plasma current and pressure profiles. Acceptable sensitivity in the deduced current profile can be obtained if the relative noise in the measured image can be kept in the range of 1% or less. Tests on the Pegasus Toroidal Experiment indicate very flat safety factor profiles in the plasma interior.

  2. A slowly rotating hollow sphere in a magnetic field: First steps to de-spin a space object

    NASA Astrophysics Data System (ADS)

    Youngquist, Robert C.; Nurge, Mark A.; Starr, Stanley O.; Leve, Frederick A.; Peck, Mason

    2016-03-01

    Modeling the interaction of a slowly rotating hollow conducting sphere in a magnetic field provided an understanding of the dynamics of orbiting space objects moving through the Earth's magnetic field. This analysis, performed in the late 1950s and limited to uniform magnetic fields, was innovative and acknowledged the pioneers who first observed rotary magnetism, in particular, the seminal work of Hertz in 1880. Now, there is interest in using a magnetic field produced by one space object to stop the spin of a second object so that docking can occur. In this paper, we consider, yet again, the interaction of a rotating hollow sphere in a magnetic field. We show that the predicted results can be tested experimentally, making this an interesting advanced student project. This analysis also sheds light on a rich set of previously unaddressed behaviors involving eddy currents.

  3. Magnetic anisotropy, scanning electron microscopy, and X ray pole figure goniometry study of inclination shallowing in a compacting clay-rich sediment

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.

    1992-12-01

    Anisotropy of anhysteretic remanence (AAR), scanning electron microscopy (SEM), and X ray pole figure goniometry studies of clay-rich sediments were conducted to delineate the interactions between magnetite and clay particles which cause inclination shallowing during compaction. These studies used synthetic sediments composed of kaolinite or illite and two grain sizes of mgnetite, 0.45 μm and 2-3 μm. Natural marine sediments which contained 40-50% clay were also used. The sediments were compacted by pressures as high as 0.157 MPa. The sediments' porosity decrease suggests that the compaction experiments model burial depths up to 400-500 m. The main result of this study is that inclination shallowing and void ratio versus pressure curves show two points where behavior changes. A rapid decrease in inclination and void ratio occurs up to a pressure of 0.02 MPa. This is accompanied by a magnetic intensity decrease of 20-30%. Compaction at pressures between 0.02 MPa and 0.05 MPa causes a further decrease in these parameters at moderate rates, while compaction at pressures above 0.05 MPa causes very little change. Percent magnetic anisotropy and X ray pole figure intensity ratio versus pressure curves show only one point where behavior changes at 0.05 MPa with a rapid increase at lower pressures and little change at higher pressures. A model to explain this behavior, based on the SEM obsevations as well as the magnetic anisotropy, pole figure, and inclination data, suggests that compaction up to 0.02 MPa causes a decrease in pore volume with little reorientation of clay particles. Some magnetic particles are firmly attached to clay particles, whereas other loosely attached particles are either randomized or subvertical ones are preferentially disturbed causing inclination shallowing and an intensity decrease. At pressures between 0.02 MPa and 0.05 MPa, magnetite particles have become firmly attached to clay particles and start to follow the reorientation of clay

  4. Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

    SciTech Connect

    Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine; Villeroy, Benjamin; Leridon, Brigitte

    2013-10-28

    We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

  5. ACCELERATING COMPACT OBJECT MERGERS IN TRIPLE SYSTEMS WITH THE KOZAI RESONANCE: A MECHANISM FOR 'PROMPT' TYPE Ia SUPERNOVAE, GAMMA-RAY BURSTS, AND OTHER EXOTICA

    SciTech Connect

    Thompson, Todd A.

    2011-11-10

    White dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers may produce Type Ia supernovae and gamma-ray bursts (GRBs), respectively. A general problem is how to produce binaries with semi-major axes small enough to merge in significantly less than the Hubble time (t{sub H}), and thus accommodate the observation that these events closely follow episodes of star formation. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and reducing its gravitational wave (GW) merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t{sub merge} < t{sub H}. In principle, Chandrasekhar-mass binaries with P {approx} 300 days can merge in {approx}< t{sub H} if they contain a prograde solar-mass tertiary at high enough inclination. For retrograde tertiaries, the maximum P such that t{sub merge} {approx}< t{sub H} is yet larger. In contrast, P {approx}< 0.3 days is required in the absence of a tertiary. I discuss implications of these findings for the production of transients formed via compact object binary mergers. Based on the statistics of solar-type binaries, I argue that many such binaries should be in triple systems affected by the Kozai resonance. If true, expectations for the mHz GW signal from individual sources, the diffuse background, and the foreground for GW experiments like LISA are modified. This work motivates future studies of triples systems of A, B, and O stars, and new types of searches for WD-WD binaries in triple systems.

  6. THE MASS-LOSS-INDUCED ECCENTRIC KOZAI MECHANISM: A NEW CHANNEL FOR THE PRODUCTION OF CLOSE COMPACT OBJECT-STELLAR BINARIES

    SciTech Connect

    Shappee, Benjamin J.; Thompson, Todd A. E-mail: thompson@astronomy.ohio-state.edu

    2013-03-20

    Over a broad range of initial inclinations and eccentricities, an appreciable fraction of hierarchical triple star systems with similar masses are essentially unaffected by the Kozai-Lidov mechanism (KM) until the primary in the central binary evolves into a compact object. Once it does, it may be much less massive than the other components in the ternary, enabling the 'eccentric Kozai mechanism (EKM)': the mutual inclination between the inner and outer binaries can flip signs driving the inner binary to very high eccentricity, leading to a close binary or collision. We demonstrate this 'mass-loss-induced eccentric Kozai' (MIEK) mechanism by considering an example system and defining an ad hoc minimal separation between the inner two members at which tidal effects become important. For fixed initial masses and semimajor axes, but uniform distributions of eccentricity and cosine of the mutual inclination, {approx}10% of systems interact tidally or collide while the primary is on the main sequence (MS) due to the KM or EKM. Those affected by the EKM are not captured by earlier quadrupole-order secular calculations. We show that fully {approx}30% of systems interact tidally or collide for the first time as the primary swells to AU scales, mostly as a result of the KM. Finally, {approx}2% of systems interact tidally or collide for the first time after the primary sheds most of its mass and becomes a white dwarf (WD), mostly as a result of the MIEK mechanism. These findings motivate a more detailed study of mass loss in triple systems and the formation of close neutron star (NS)/WD-MS and NS/WD-NS/WD binaries without an initial common envelope phase.

  7. Accelerating Compact Object Mergers in Triple Systems with the Kozai Resonance: A Mechanism for "Prompt" Type Ia Supernovae, Gamma-Ray Bursts, and Other Exotica

    NASA Astrophysics Data System (ADS)

    Thompson, Todd A.

    2011-11-01

    White dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers may produce Type Ia supernovae and gamma-ray bursts (GRBs), respectively. A general problem is how to produce binaries with semi-major axes small enough to merge in significantly less than the Hubble time (t H), and thus accommodate the observation that these events closely follow episodes of star formation. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and reducing its gravitational wave (GW) merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t merge < t H. In principle, Chandrasekhar-mass binaries with P ~ 300 days can merge in <~ t H if they contain a prograde solar-mass tertiary at high enough inclination. For retrograde tertiaries, the maximum P such that t merge <~ t H is yet larger. In contrast, P <~ 0.3 days is required in the absence of a tertiary. I discuss implications of these findings for the production of transients formed via compact object binary mergers. Based on the statistics of solar-type binaries, I argue that many such binaries should be in triple systems affected by the Kozai resonance. If true, expectations for the mHz GW signal from individual sources, the diffuse background, and the foreground for GW experiments like LISA are modified. This work motivates future studies of triples systems of A, B, and O stars, and new types of searches for WD-WD binaries in triple systems.

  8. Paramagnetism in colour superconductivity and compact stars

    NASA Astrophysics Data System (ADS)

    Ferrer, Efrain J.; de la Incera, Vivian

    2007-06-01

    It is quite plausible that colour superconductivity occurs in the inner regions of neutron stars. At the same time, it is known that strong magnetic fields exist in the interior of these compact objects. In this paper we discuss some important effects that can occur in the colour superconducting core of compact stars due to the presence of the stars' magnetic field. In particular, we consider the modification of the gluon dynamics for a colour superconductor with three massless quark flavours in the presence of an external magnetic field. We show that the long-range component of the external magnetic field that penetrates the colour-flavour locked phase produces an instability for field values larger than the charged gluons' Meissner mass. As a consequence, the ground state is restructured forming a vortex state characterized by the condensation of charged gluons and the creation of magnetic flux tubes. In the vortex state the magnetic field outside the flux tubes is equal to the applied one, while inside the tubes its strength increases by an amount that depends on the amplitude of the gluon condensate. This paramagnetic behaviour of the colour superconductor can be relevant for the physics of compact stars.

  9. Fourier space derivation of the demagnetization tensor for uniformly magnetized objects of cylindrical symmetry

    NASA Astrophysics Data System (ADS)

    Lang, Franz; Blundell, Stephen J.

    2016-03-01

    We derive an analytical solution for the demagnetization tensor of a cylinder of finite size and uniform magnetization in both Cartesian and cylindrical coordinate systems, by employing a recently developed Fourier space approach. Simple arguments are given to show that a previously published solution using this approach is incomplete, and a detailed and comprehensive derivation containing the necessary corrections is given. The corrected result is shown to be in agreement with older analytical solutions based on an electrostatic potential approach. We subsequently expand our solution to objects of general cylindrical symmetry and derive an expression for the demagnetization tensor that involves a single remaining integral over a finite domain, enabling the use of conventional numerical tools to efficiently calculate the demagnetization tensor.

  10. A Multi-Object Inversion Approach for Efficient Magnetic Discrimination of Unexploded Ordnance

    NASA Astrophysics Data System (ADS)

    Billings, S.; Oldenburg, D.; Pasion, L.

    2005-05-01

    Magnetometery is one of the primary methods used for detecting buried unexploded ordnances, either in a standalone mode, or in conjunction with electromagnetic induction. UXO's and other metallic debris generally appear as dipolar anomalies overprinting larger scale magnetic features due to near-surface magnetite variations and the regional geology. Non-linear high-pass filters are usually used to remove the larger scale effects and the remaining dipolar anomalies are inverted one at a time by an efficient bound-constrained optimization algorithm. This process works well when the individual anomalies are well separated and the geological variations are at larger scales than the UXO anomalies. When these conditions don't apply the inversion results are unreliable and the process of inverting each anomaly becomes time-consuming and unwieldy. We have developed an efficient multi-object inversion routine that allows simultaneous inversion of an arbitrary number of dipolar anomalies. Providing a good initial guess as to the number, location, magnitude and orientation of each dipole is critical to the success of the algorithm. We have found that an Automated Wavelet Detection algorithm we developed in a previous paper is ideal for this purpose. The multi-object inversion approach is very effective in most situations, but, like the original single-object approach, has trouble dealing with datasets with significant geological contamination. In an effort to overcome this problem we outline a framework for coupling our multi-object inversion scheme with an equivalent layer technique that attempts to model the background geology.

  11. Distinctions between manipulation and function knowledge of objects: evidence from functional magnetic resonance imaging.

    PubMed

    Boronat, Consuelo B; Buxbaum, Laurel J; Coslett, H Branch; Tang, Kathy; Saffran, Eleanor M; Kimberg, Daniel Y; Detre, John A

    2005-05-01

    A prominent account of conceptual knowledge proposes that information is distributed over visual, tactile, auditory, motor and verbal-declarative attribute domains to the degree to which these features were activated when the knowledge was acquired [D.A. Allport, Distributed memory, modular subsystems and dysphagia, In: S.K. Newman, R. Epstein (Eds.), Current perspectives in dysphagia, Churchill Livingstone, Edinburgh, 1985, pp. 32-60]. A corollary is that when drawing upon this knowledge (e.g., to answer questions), particular aspects of this distributed information is re-activated as a function of the requirements of the task at hand [L.J. Buxbaum, E.M. Saffran, Knowledge of object manipulation and object function: dissociations in apraxic and non-apraxic subjects. Brain and Language, 82 (2002) 179-199; L.J. Buxbaum, T. Veramonti, M.F. Schwartz, Function and manipulation tool knowledge in apraxia: knowing 'what for' but not 'how', Neurocase, 6 (2000) 83-97; W. Simmons, L. Barsalou, The similarity-in-topography principle: Reconciling theories of conceptual deficits, Cognitive Neuropsychology, 20 (2003) 451-486]. This account predicts that answering questions about object manipulation should activate brain regions previously identified as components of the distributed sensory-motor system involved in object use, whereas answering questions about object function (that is, the purpose that it serves) should activate regions identified as components of the systems supporting verbal-declarative features. These predictions were tested in a functional magnetic resonance imaging (fMRI) study in which 15 participants viewed picture or word pairs denoting manipulable objects and determined whether the objects are manipulated similarly (M condition) or serve the same function (F condition). Significantly greater and more extensive activations in the left inferior parietal lobe bordering the intraparietal sulcus were seen in the M condition with pictures and, to a lesser

  12. Hiding objects in AC magnetic fields of power grid frequency by two-shell ferromagnetic/superconducting cloak

    NASA Astrophysics Data System (ADS)

    Šouc, J.; Solovyov, M.; Gömöry, F.

    2016-07-01

    Performance of magnetic cloak made from commercially available materials has been tested by verifying its ability to suppress the magnetic signatures of metallic and ferromagnetic objects. The range of magnetic field amplitudes from 0.1 to 10 mT and frequencies around 50-60 Hz were used. The cloak combines the inner tube from high-temperature superconductor that should be cooled by liquid nitrogen, with the outer tube made from MnZn ferrite powder mixed in plastic matter. Superconductor is in the form of tapes wound in helical manner on a round former. Such design is promising when the objects with dimensions reaching several centimeters should be cloaked. Performance of the small model manufactured following this design was demonstrated by observing ˜20 times reduction of the magnetic signature of metallic or ferromagnetic objects.

  13. Ultraviolet Spectra of Two Magnetic White Dwarfs and Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey

    NASA Technical Reports Server (NTRS)

    Wegner, Gary A.

    1987-01-01

    Low resolution International Ultraviolet Explorer (IUE) spectroscopic observations of two magnetic white dwarfs BPM25114 and K813-14 were obtained using both the SWP and LWP cameras. The first object has an observed magnetic field of 4 x 10(7) Gauss and the second has one of 3 x 10(7) Gauss. Both objects have overall spectral energy distributions appropriate for cool DA white dwarfs with T(eff) near 10,000 K and accordingly show strong lambda lambda 1400 and 1600 absorption in their spectra. Compared to non-magnetic DA white dwarfs of comparable effective temperature, there are some differences in the profiles, presumably produced by the magnetic fields in these objects. In addition, the ultraviolet spectra of a number of hot subluminous stars in the Kiso Schmidt survey were observed.

  14. Unidentified Bright Objects on Brain Magnetic Resonance Imaging Affect Vestibular Neuritis

    PubMed Central

    Kim, Ji Chan; Chang, Dong Sik; Cho, Chin Saeng

    2015-01-01

    Objectives The aim of this study was to investigate the differences in clinical manifestations of in two groups of vestibular neuritis (VN) patients with or without unidentified bright objects (UBOs). Methods A prospective, observational study with 46 patients diagnosed with VN between May 2013 and November 2013 was executed. A caloric test, a cervical vestibular-evoked myogenic potentials (cVEMPs) test, brain magnetic resonance imaging (MRI), spontaneous nystagmus test, head impulse test, and head-shaking nystagmus test were performed. Results Of the patients, 56.5% (n=26) were classified as UBO-positive by MRI. These showed lower caloric weakness and more prominent cVEMP asymmetry compared with the UBO-negative group (P<0.05). Total VN (TVN) was the most common in the UBO-positive group (45.0%), followed by superior VN (SVN, 30.0%), and inferior VN (IVN, 25.0%). However, in the UBO-negative group, SVN (75.0%) was the most common, followed by TVN and IVN (P<0.05). The recovery rate was not influenced by UBOs (P>0.05). Conclusion UBOs on T2-weighted or fluid attenuated inversion recovery MRI may affect the patterns of the vestibular nerve in patients with VN. PMID:26622955

  15. Correlation between subjective and objective assessment of magnetic resonance (MR) images.

    PubMed

    Chow, Li Sze; Rajagopal, Heshalini; Paramesran, Raveendran

    2016-07-01

    Medical Image Quality Assessment (IQA) plays an important role in assisting and evaluating the development of any new hardware, imaging sequences, pre-processing or post-processing algorithms. We have performed a quantitative analysis of the correlation between subjective and objective Full Reference - IQA (FR-IQA) on Magnetic Resonance (MR) images of the human brain, spine, knee and abdomen. We have created a MR image database that consists of 25 original reference images and 750 distorted images. The reference images were distorted with six types of distortions: Rician Noise, Gaussian White Noise, Gaussian Blur, DCT compression, JPEG compression and JPEG2000 compression, at various levels of distortion. Twenty eight subjects were chosen to evaluate the images resulting in a total of 21,700 human evaluations. The raw scores were then converted to Difference Mean Opinion Score (DMOS). Thirteen objective FR-IQA metrics were used to determine the validity of the subjective DMOS. The results indicate a high correlation between the subjective and objective assessment of the MR images. The Noise Quality Measurement (NQM) has the highest correlation with DMOS, where the mean Pearson Linear Correlation Coefficient (PLCC) and Spearman Rank Order Correlation Coefficient (SROCC) are 0.936 and 0.938 respectively. The Universal Quality Index (UQI) has the lowest correlation with DMOS, where the mean PLCC and SROCC are 0.807 and 0.815 respectively. Student's T-test was used to find the difference in performance of FR-IQA across different types of distortion. The superior IQAs tested statistically are UQI for Rician noise images, Visual Information Fidelity (VIF) for Gaussian blur images, NQM for both DCT and JPEG compressed images, Peak Signal-to-Noise Ratio (PSNR) for JPEG2000 compressed images. PMID:26969762

  16. Adult Compacts.

    ERIC Educational Resources Information Center

    Further Education Unit, London (England).

    This bulletin focuses on adult compacts, three-way agreements among employers, potential employees, and trainers to provide the right kind of quality training to meet the employers' requirements. Part 1 is an executive summary of a report of the Adult Compacts Project, which studied three adult compacts in Birmingham and Loughborough, England, and…

  17. Diffusion-mediated dephasing in the dipole field around a single spherical magnetic object.

    PubMed

    Buschle, Lukas R; Kurz, Felix T; Kampf, Thomas; Triphan, Simon M F; Schlemmer, Heinz-Peter; Ziener, Christian Herbert

    2015-11-01

    In this work, the time evolution of the free induction decay caused by the local dipole field of a spherical magnetic perturber is analyzed. The complicated treatment of the diffusion process is replaced by the strong-collision-approximation that allows a determination of the free induction decay in dependence of the underlying microscopic tissue parameters such as diffusion coefficient, sphere radius and susceptibility difference. The interplay between susceptibility- and diffusion-mediated effects yields several dephasing regimes of which, so far, only the classical regimes of motional narrowing and static dephasing for dominant and negligible diffusion, respectively, were extensively examined. Due to the asymmetric form of the dipole field for spherical objects, the free induction decay exhibits a complex component in contradiction to the cylindrical case, where the symmetric local dipole field only causes a purely real induction decay. Knowledge of the shape of the corresponding frequency distribution is necessary for the evaluation of more sophisticated pulse sequences and a detailed understanding of the off-resonance distribution allows improved quantification of transverse relaxation. PMID:26133269

  18. Demonstration of Single-Shot Picosecond Time-Resolved MeV Electron Imaging Using a Compact Permanent Magnet Quadrupole Based Lens

    NASA Astrophysics Data System (ADS)

    Cesar, D.; Maxson, J.; Musumeci, P.; Sun, Y.; Harrison, J.; Frigola, P.; O'Shea, F. H.; To, H.; Alesini, D.; Li, R. K.

    2016-07-01

    We present the results of an experiment where a short focal length (˜1.3 cm ), permanent magnet electron lens is used to image micron-size features (of a metal sample) with a single shot from an ultrahigh brightness picosecond-long 4 MeV electron beam emitted by a radio-frequency photoinjector. Magnification ratios in excess of 30 × were obtained using a triplet of compact, small gap (3.5 mm), Halbach-style permanent magnet quadrupoles with nearly 600 T /m field gradients. These results pave the way towards single-shot time-resolved electron microscopy and open new opportunities in the applications of high brightness electron beams.

  19. Demonstration of Single-Shot Picosecond Time-Resolved MeV Electron Imaging Using a Compact Permanent Magnet Quadrupole Based Lens.

    PubMed

    Cesar, D; Maxson, J; Musumeci, P; Sun, Y; Harrison, J; Frigola, P; O'Shea, F H; To, H; Alesini, D; Li, R K

    2016-07-01

    We present the results of an experiment where a short focal length (∼1.3  cm), permanent magnet electron lens is used to image micron-size features (of a metal sample) with a single shot from an ultrahigh brightness picosecond-long 4 MeV electron beam emitted by a radio-frequency photoinjector. Magnification ratios in excess of 30× were obtained using a triplet of compact, small gap (3.5 mm), Halbach-style permanent magnet quadrupoles with nearly 600  T/m field gradients. These results pave the way towards single-shot time-resolved electron microscopy and open new opportunities in the applications of high brightness electron beams. PMID:27447510

  20. Development of a compact HTS lead unit for the SC correction coils of the SuperKEKB final focusing magnet system

    NASA Astrophysics Data System (ADS)

    Zong, Zhanguo; Ohuchi, Norihito; Tsuchiya, Kiyosumi; Arimoto, Yasushi

    2016-09-01

    Forty-three superconducting (SC) correction coils with maximum currents of about 60 A are installed in the SuperKEKB final focusing magnet system. Current leads to energize the SC correction coils should have an affordable heat load and fit the spatial constraints in the service cryostat where the current leads are installed. To address the requirements, design optimization of individual lead was performed with vapor cooled current lead made of a brass material, and a compact unit was designed to accommodate eight current leads together in order to be installed with one port in the service cryostat. The 2nd generation high temperature SC (HTS) tape was adopted and soldered at the cold end of the brass current lead to form a hybrid HTS lead structure. A prototype of the compact lead unit with HTS tape was constructed and tested with liquid helium (LHe) environment. This paper presents a cryogenic measurement system to simulate the real operation conditions in the service cryostat, and analysis of the experimental results. The measured results showed excellent agreement with the theoretical analysis and numerical simulation. In total, 11 sets of the compact HTS lead units were constructed for the 43 SC correction coils at KEK. One set from the mass production was tested in cryogenic conditions, and exhibited the same performance as the prototype. The compact HTS lead unit can feed currents to four SC correction coils simultaneously with the simple requirement of controlling and monitoring helium vapor flow, and has a heat load of about 0.762 L/h in terms of LHe consumption.

  1. Compact, Low-Profile Power Converters: Highly-Laminated, High-Saturation-Flux-Density, Magnetic Cores for On-Chip Inductors in Power Converter Applications

    SciTech Connect

    2010-09-01

    ADEPT Project: Georgia Tech is creating compact, low-profile power adapters and power bricks using materials and tools adapted from other industries and from grid-scale power applications. Adapters and bricks convert electrical energy into useable power for many types of electronic devices, including laptop computers and mobile phones. These converters are often called wall warts because they are big, bulky, and sometimes cover up an adjacent wall socket that could be used to power another electronic device. The magnetic components traditionally used to make adapters and bricks have reached their limits; they can't be made any smaller without sacrificing performance. Georgia Tech is taking a cue from grid-scale power converters that use iron alloys as magnetic cores. These low-cost alloys can handle more power than other materials, but the iron must be stacked in insulated plates to maximize energy efficiency. In order to create compact, low-profile power adapters and bricks, these stacked iron plates must be extremely thin-only hundreds of nanometers in thickness, in fact. To make plates this thin, Georgia Tech is using manufacturing tools used in microelectromechanics and other small-scale industries.

  2. CQ-4: a 4 MA, 500ns Compact Pulsed Power Generator Dedicated to Magnetically Driven Quasi-isentropic Compression Experiments (ICE) and Hypervelocity Flyer Plates

    NASA Astrophysics Data System (ADS)

    Wang, Guiji; Zhao, Jianheng; Sun, Chengwei; Kuai, Bin; Mo, Jianjun; Wu, Gang

    2011-06-01

    Compact pulsed power generators have been widely used to produce high magnetic pressure to study dynamic behaviors of materials and do some hypervelocity impact experiments. After the compact pulsed power generator CQ-1.5 developed by us, a larger current and shorter rise time compact pulsed power generator CQ-4 has been designed and being constructed. The generator CQ-4 is composed of 20 energy-storage modules in parallel, of which is constituted by a 1.6 μF, 100 kV capacitor and a coaxial field-distortion spark gas switch with inductance of 25 nH. The energy is transmitted by the aluminum strip transmission lines insulated by 16 layers of Mylar films, of which is 0.1 mm in thickness. Before the short-circuit load, 72 peaking capacitors in parallel with the energy-storage capacitors are used to shape the discharging current waveforms in load. Each peaking capacitor is with rated capacitance of 0.1 μF and rated voltage of 120 kV. When the capacitor is charged to 70-80 kV, the peak current can reach 4-5MA, and the rise time is 400-500 ns (0-100%). The expected magnetic pressure can be up to 100GPa on the metallic loads and a hypervelocity of 12-15 km/s can be reached for the aluminum flyer plates with size of 10 mm in diameter and 1.0 mm in thickness.

  3. MAGNETIC FIELDS IN LARGE-DIAMETER H II REGIONS REVEALED BY THE FARADAY ROTATION OF COMPACT EXTRAGALACTIC RADIO SOURCES

    SciTech Connect

    Harvey-Smith, L.; Madsen, G. J.; Gaensler, B. M.

    2011-08-01

    We present a study of the line-of-sight magnetic fields in five large-diameter Galactic H II regions. Using the Faraday rotation of background polarized radio sources, as well as dust-corrected H{alpha} surface brightness as a probe of electron density, we estimated the strength and orientation of the magnetic field along 93 individual sight lines through the H II regions. Each of the H II regions displayed a coherent magnetic field. The magnetic field strength (line-of-sight component) in the regions ranges from 2 to 6 {mu}G, which is similar to the typical magnetic field strength in the diffuse interstellar medium. We investigated the relationship between magnetic field strength and electron density in the five H II regions. The slope of magnetic field versus density in the low-density regime (0.8 cm{sup -3} < n{sub e} <30 cm{sup -3}) is very slightly above zero. We also calculated the ratio of thermal to magnetic pressure, {beta}{sub th}, for each data point, which fell in the range 1.01 < {beta}{sub th} < 25. Finally, we studied the orientation of the magnetic field in the solar neighborhood (d < 1.1 kpc) using our data from five H II regions along with existing measurements of the line-of-sight magnetic field strength from polarized pulsars whose distances have been determined from their annual parallax. We identify a net direction for the magnetic field in the solar neighborhood, but find no evidence for a preferred vertical direction of the magnetic field above or below the Galactic plane.

  4. Generation of circularly polarized radiation from a compact plasma-based extreme ultraviolet light source for tabletop X-ray magnetic circular dichroism studies

    SciTech Connect

    Wilson, Daniel; Rudolf, Denis Juschkin, Larissa; Weier, Christian; Adam, Roman; Schneider, Claus M.; Winkler, Gerrit; Frömter, Robert; Danylyuk, Serhiy; Bergmann, Klaus; Grützmacher, Detlev

    2014-10-15

    Generation of circularly polarized light in the extreme ultraviolet (EUV) spectral region (about 25 eV–250 eV) is highly desirable for applications in spectroscopy and microscopy but very challenging to achieve in a small-scale laboratory. We present a compact apparatus for generation of linearly and circularly polarized EUV radiation from a gas-discharge plasma light source between 50 eV and 70 eV photon energy. In this spectral range, the 3p absorption edges of Fe (54 eV), Co (60 eV), and Ni (67 eV) offer a high magnetic contrast often employed for magneto-optical and electron spectroscopy as well as for magnetic imaging. We simulated and designed an instrument for generation of linearly and circularly polarized EUV radiation and performed polarimetric measurements of the degree of linear and circular polarization. Furthermore, we demonstrate first measurements of the X-ray magnetic circular dichroism at the Co 3p absorption edge with a plasma-based EUV light source. Our approach opens the door for laboratory-based, element-selective spectroscopy of magnetic materials and spectro-microscopy of ferromagnetic domains.

  5. Dark compact planets

    NASA Astrophysics Data System (ADS)

    Tolos, Laura; Schaffner-Bielich, Jürgen

    2015-12-01

    We investigate compact objects formed by dark matter admixed with ordinary matter made of neutron-star matter and white-dwarf material. We consider non-self annihilating dark matter with an equation of state given by an interacting Fermi gas. We find new stable solutions, dark compact planets, with Earth-like masses and radii from a few Km to few hundred Km for weakly interacting dark matter which are stabilized by the mutual presence of dark matter and compact star matter. For the strongly interacting dark matter case, we obtain dark compact planets with Jupiter-like masses and radii of few hundred Km. These objects could be detected by observing exoplanets with unusually small radii. Moreover, we find that the recently observed 2 M⊙ pulsars set limits on the amount of dark matter inside neutron stars which is, at most, 1 0-6 M⊙ .

  6. Magnetohydrodynamic analysis of the interaction of magnetized plasma flow with a perfect-conducting object

    SciTech Connect

    Nishida, Hiroyuki; Abe, Takashi

    2010-05-15

    In this study, a supersonic and super-Alfvenic magnetized plasma flow past a perfect-conducting cylinder was simulated based on single-fluid ideal magnetohydrodynamics to clarify the piling-up process of the magnetic field frozen in the plasma flow. Therefore, the magnetic field is assumed to be perpendicular to both the cylinder axis and the flow direction. Simulation results indicated that the cylinder continuously traps the magnetic field and an unsteady flow field is generated. Even though the drag force exerting on the cylinder is expected to continuously increase with the continuous increase in the trapped magnetic field and the shock layer, the intensity of magnetic flux density at the cylinder surface is saturated at a certain value and the drag force is also saturated. The saturated values are characterized by the Alfven Mach number of the mainstream. Furthermore, on this flow structure the wake flow in which magnetic reconnection plays an important role was found to have a strong influence by using the pseudomagnetic reconnection in the ideal magnetohydrodynamic flow.

  7. Equation of state for the magnetic-color-flavor-locked phase and its implications for compact star models

    SciTech Connect

    Paulucci, L.; Ferrer, Efrain J.; Incera, Vivian de la; Horvath, J. E.

    2011-02-15

    Using the solutions of the gap equations of the magnetic-color-flavor-locked (MCFL) phase of paired quark matter in a magnetic field, and taking into consideration the separation between the longitudinal and transverse pressures due to the field-induced breaking of the spatial rotational symmetry, the equation of state of the MCFL phase is self-consistently determined. This result is then used to investigate the possibility of absolute stability, which turns out to require a field-dependent 'bag constant' to hold. That is, only if the bag constant varies with the magnetic field, there exists a window in the magnetic field vs bag constant plane for absolute stability of strange matter. Implications for stellar models of magnetized (self-bound) strange stars and hybrid (MCFL core) stars are calculated and discussed.

  8. Radiation Pressure-Driven Magnetic Disk Winds in Broad Absorption Line Quasi-Stellar Objects

    NASA Technical Reports Server (NTRS)

    DeKool, Martin; Begelman, Mitchell C.

    1995-01-01

    We explore a model in which QSO broad absorption lines (BALS) are formed in a radiation pressure-driven wind emerging from a magnetized accretion disk. The magnetic field threading the disk material is dragged by the flow and is compressed by the radiation pressure until it is dynamically important and strong enough to contribute to the confinement of the BAL clouds. We construct a simple self-similar model for such radiatively driven magnetized disk winds, in order to explore their properties. It is found that solutions exist for which the entire magnetized flow is confined to a thin wedge over the surface of the disk. For reasonable values of the mass-loss rate, a typical magnetic field strength such that the magnetic pressure is comparable to the inferred gas pressure in BAL clouds, and a moderate amount of internal soft X-ray absorption, we find that the opening angle of the flow is approximately 0.1 rad, in good agreement with the observed covering factor of the broad absorption line region.

  9. Compact plasma accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2004-01-01

    A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

  10. Magnetization damping in two-component metal oxide micropowder and nanopowder compacts by broadband ferromagnetic resonance measurements

    NASA Astrophysics Data System (ADS)

    Youssef, Jamal Ben; Brosseau, Christian

    2006-12-01

    The microwave damping mechanisms in magnetic inhomogeneous systems have displayed a richness of phenomenology that has attracted widespread interest over the years. Motivated by recent experiments, we report an extensive experimental study of the Gilbert damping parameter of multicomponent metal oxides micro- and nanophases. We label the former by M samples, and the latter by N samples. The main thrust of this examination is the magnetization dynamics in systems composed of mixtures of magnetic (γ-Fe2O3) and nonmagnetic (ZnO and epoxy resin) materials fabricated via powder processing. Detailed ferromagnetic resonance (FMR) measurements on N and M samples are described so to determine changes in the microwave absorption over the 6-18GHz frequency range as a function of composition and static magnetic field. The FMR linewidth and the field dependent resonance were measured for the M and N samples, at a given volume fraction of the magnetic phase. The asymmetry in the form and change in the linewidth for the M samples are caused by the orientation distribution of the local anisotropy fields, whereas the results for the N samples suggest that the linewidth is very sensitive to details of the spatial magnetic inhomogeneities. For N samples, the peak-to-peak linewidth increases continuously with the volume content of magnetic material. The influence of the volume fraction of the magnetic phase on the static internal field was also investigated. Furthermore, important insights are gleaned through analysis of the interrelationship between effective permeability and Gilbert damping constant. Different mechanisms have been considered to explain the FMR linewidth: the intrinsic Gilbert damping, the broadening induced by the magnetic inhomogeneities, and the extrinsic magnetic relaxation. We observed that the effective Gilbert damping constant of the series of N samples are found to be substantially smaller in comparison to M samples. This effect is attributed to the surface

  11. VIBRATION COMPACTION

    DOEpatents

    Hauth, J.J.

    1962-07-01

    A method of compacting a powder in a metal container is described including the steps of vibrating the container at above and below the resonant frequency and also sweeping the frequency of vibration across the resonant frequency several times thereby following the change in resonant frequency caused by compaction of the powder. (AEC)

  12. Proceedings of the seventh symposium on the physics and technology of compact toroids in the Magnetic Fusion Energy Program

    SciTech Connect

    Sherwood, A.R.

    1986-09-01

    The Seventh Symposium on Compact Toroid (CT) Research was held in Santa Fe, New Mexico, on May 21-23, 1985. As has been the case for the last few CT symposia, CT research progress was reported in a combination of invited talks and poster sessions. The following record of these presentations in the form of four page papers is in keeping with the format followed in previous years. We have continued the practice of dividing the papers into three subject categories - spheromak, FRC (Field Reversed Configuration), and other (mostly particle rings).

  13. RMF concept: a rotating-magnetic-field technique for driving steady plasma currents in compact toroid devices

    SciTech Connect

    McKenna, K.F.

    1980-09-01

    The generation and/or sustaining of a Compact Toroid (CT) configuration using the RMF technique is a relatively new and unknown concept. In this report the basic principles, historical development, and current theoretical understanding of this concept are reviewed. Significant experimental and theoretical results, potential problem areas, and recommendations for the direction of future work are discussed. An illustrative analysis of the application of the RMF technique to a CT reactor is presented. The results of a recent experiment, the Rotamak, in which a Spheromak-like CT plasma was produced using the RMF technique, are presented.

  14. A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

    NASA Astrophysics Data System (ADS)

    Feng, Yejun; Silevitch, D. M.; Rosenbaum, T. F.

    2014-03-01

    We present the design of an efficient bellows-controlled diamond anvil cell that is optimized for use inside the bores of high-field superconducting magnets in helium-3 cryostats, dilution refrigerators, and commercial physical property measurement systems. Design of this non-magnetic pressure cell focuses on in situ pressure tuning and measurement by means of a helium-filled bellows actuator and fiber-coupled ruby fluorescence spectroscopy, respectively. We demonstrate the utility of this pressure cell with ac susceptibility measurements of superconducting, ferromagnetic, and antiferromagnetic phase transitions to pressures exceeding 8 GPa. This cell provides an opportunity to probe charge and magnetic order continuously and with high resolution in the three-dimensional Magnetic Field-Pressure-Temperature parameter space.

  15. A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

    SciTech Connect

    Feng, Yejun; Silevitch, D. M.; Rosenbaum, T. F.

    2014-03-15

    We present the design of an efficient bellows-controlled diamond anvil cell that is optimized for use inside the bores of high-field superconducting magnets in helium-3 cryostats, dilution refrigerators, and commercial physical property measurement systems. Design of this non-magnetic pressure cell focuses on in situ pressure tuning and measurement by means of a helium-filled bellows actuator and fiber-coupled ruby fluorescence spectroscopy, respectively. We demonstrate the utility of this pressure cell with ac susceptibility measurements of superconducting, ferromagnetic, and antiferromagnetic phase transitions to pressures exceeding 8 GPa. This cell provides an opportunity to probe charge and magnetic order continuously and with high resolution in the three-dimensional Magnetic Field–Pressure–Temperature parameter space.

  16. Tectonic insight based on anisotropy of magnetic susceptibility and compaction studies in the Sierras Australes thrust and fold belt (southwest Gondwana boundary, Argentina)

    NASA Astrophysics Data System (ADS)

    Arzadún, Guadalupe; Tomezzoli, Renata N.; Cesaretti, Nora N.

    2016-04-01

    The Sierras Australes fold and thrust belt (Buenos Aires Province, Argentina) was in the southwestern Gondwanaland margin during the Paleozoic. The Tunas Formation (Permian) is exposed along the eastern part of it and continues eastward beneath the Claromecó Basin. Anisotropy of magnetic susceptibility (AMS) and compaction studies are described and compared with previous paleomagnetic studies with the aim of determining direction and magnitude of the main stresses acting during the sedimentation of the Tunas Formation. The anisotropy ellipsoids are triaxial with oblate or prolate shapes, reflecting different stages of layer parallel shortening during the evolution of the basin. Kmax axes trend NW-SE, parallel to the fold axes, while Kmin move from a horizontal (base) to a vertical orientation at the top of the succession, showing a change from a tectonic to almost a sedimentary fabric. The magnitude of anisotropy and compaction degree decreases toward the top of the succession. The AMS results are consistent with the outcrop structural observations and the compaction and paleomagnetic data. Regional pattern indicates a compression from the SW along this part of Gondwana, with a migration of the orogenic front and attenuation toward the NE in the foreland basin during the Upper Paleozoic. This deformation, locally assigned to the San Rafael noncollisional orogenic phase, is the result of the latitudinal movements toward the Equator of Gondwana (southern plates) and Laurentia (northern plates) during the Permian. This movement is the result of a rearrangement of the microplates that collided with Gondwana during the Late Devonian, to configure Pangea during the Triassic.

  17. Compact electromagnetically operated microfluidic system for detection of sub-200-nm magnetic labels for biosensing without external pumps

    NASA Astrophysics Data System (ADS)

    Morimoto, Y.; Takamura, T.; Sandhu, A.

    2010-05-01

    The combination of small sample analyte volumes, high sensitivity, ease of use, high speed, and portability is an important factor for the development of protocols for point of care biodiagnosis. Currently, handling small amounts of liquids is achieved using microfluidic systems but it is challenging to satisfy the remaining factors using conventional approaches based on biosensors employing detection of fluorescent labels. Thus to resolve the other requirements, biosensing systems based on the detection of functionalized superparamagnetic beads acting as "magnetic labels" are being studied as an alternative approach. Notably, for greater quantification, there are increasing demands for the use of sub-200-nm magnetic labels, which are comparable in size to actual biomolecules. However, detection of small numbers of sub-200-nm diameter magnetic beads by magnetoresistive device-based platforms is extremely challenging due to the intrinsic noise of the electronic devices. In order to overcome the limitation, we have developed a simple procedure for detecting sub-200-nm diameter magnetic labels for biosensing via magnetically induced self-assembly of superparamagnetic beads. Applying our approach to conventional microfluidic systems satisfies the most of prerequisites; however conventional microfluidic systems attached to the external pumps are yet suitable for point of care biodiagnosis. Here we propose the development of an alternative biosensing system based on our previous work that does not require external pumps to achieve miniaturization.

  18. High performance compact magnetic spectrometers for energetic ion and electron measurement in ultra intense short pulse laser solid interactions

    SciTech Connect

    Chen, H; Link, A; van Maren, R; Patel, P; Shepherd, R; Wilks, S C; Beiersdorfer, P

    2008-05-08

    Ultra intense short pulse lasers incident on solid targets can generate relativistic electrons that then accelerate energetic protons and ions. These fast electrons and ions can effectively heat the solid target, beyond the region of direct laser interaction, and are vital to realizing the fast ignition concept. To study these energetic ions and electrons produced from the laser-target interactions, we have developed a range of spectrometers that can cover a large energy range (from less than 0.1 MeV to above 100 MeV). They are physically compact and feature high performance and low cost. We will present the basic design of these spectrometers and their test results from recent laser experiments.

  19. The magnetic evolution of AR 6555 which lead to two impulsive, readily compact, X-type flares

    NASA Technical Reports Server (NTRS)

    Ambastha, A.; Fontenla, J. M.; Kalman, B.; Csepura, GY.

    1995-01-01

    We study the evolution of the vector magnetic field and the sunspot motions observed in AR 6555 during 23-26 Mar. 1991. This region displays two locations of large magnetic shear that were also sites of flare activity. The first location produced two large (X-class) flares during the period covered by our observations. The second location had larger magnetic shear than the first, but produced only small (M- and C-class) flares during our observations. We study the evolution of the photospheric magnetic field in relation to the large flares in the first location. These flares occurred around the same included polarity, and have very similar characteristics (soft X-ray light curves, energies, etc.). However, the whole active region has changed substantially in the period between them. We found several characteristics of the region that appear related to the occurrence of these flares. (1) The flares occurred near regions of large magnetic 'shear,' but not at the locations of maximum shear or maximum field. (2) Potential field extrapolations of the observed field suggest that the topology changed, prior to the first of the two flares, in such a way that a null appeared in the coarse magnetic field. (3) This null was located close to both X-class flares, and remained in that location for a few days while the two flares were observed. (4) The flaring region has a pattern of vector field and sunspot motions in which material is 'squeezed' along the polarity inversion line. This pattern is very different from that usually associated with shearing arcades, but it is similar to that suggested previously by Fontenla and Davis. The vertical electric currents, inferred from the transverse field, are consistent with this pattern. (5) A major reconfiguration of the longitudinal field and the vertical electric currents occurred just prior to the first of the two flares. Both changes imply substantial variations of the magnetic structure of the region. On the basis of the

  20. The Magnetic Evolution of AR 6555 which led to Two Impulsive, Relatively Compact, X-Type Flares

    NASA Technical Reports Server (NTRS)

    Fontenla, J. M.; Ambastha, A.; Kalman, B.; Csepura, Gy.

    1995-01-01

    We study the evolution of the vector magnetic field and the sunspot motions observed in AR 6555 during 1991 March 23-26. This region displays two locations of large magnetic shear that were also sites of flare activity. The first location produced two large (X-class) flares during the period covered by our observations. The second location had larger magnetic shear than the first but produced only small (M- and C-class) flares during our observations. We study the evolution of the photospheric magnetic field in relation to the large flares in the first location. These flares occurred around the same included polarity and have very similar characteristics (soft X-ray light curves, energies, etc,). However, the whole active region has changed substantially in the period between them. We found several characteristics of the region that appear related to the occurrence of these flares: (1) The flares occurred near regions of large magnetic 'shear' but not at the locations of maximum shear or maximum field. (2) Potential field extrapolations of the observed field suggest that the topology changed, prior to the first of the two flares, in such a way that a null appeared in the coarse magnetic field. (3) This null was located close to both X-class flares and remained in that location for a few days while the two flares were observed. (4) The flaring region has a pattern of vector field and sunspot motions in which material is 'squeezed' along the polarity inversion line. This pattern is very different from that usually associated with shearing arcades, but it is similar to that suggested previously by Fontenia and Davis. The vertical electric currents, inferred from the transverse field, are consistent with this pattern. (5) A major reconfiguration of the longitudinal field and the vertical electric currents occurred just prior to the first of the two flares. Both changes imply substantial variations of the magnetic structure of the region. On the basis of the available

  1. Observational signatures of sub-Larmor scale magnetic fields in astrophysical objects and HEAD lab experiments

    NASA Astrophysics Data System (ADS)

    Medvedev, Mikhail

    2010-02-01

    An extensive body of studies indicate that small-scale (sub-Larmor-scale) magnetic turbulence are produced at relativistic shocks, in reconnection events and other high-energy density environments. Here we present a general description of radiation produced by relativistic electrons moving in such fields and stress its non-synchrotron spectral characteristics. We illustrate the results with spectral data from gamma-ray burst observations. )

  2. Self-Consistent Thermal Accretion Disk Corona Models for Compact Objects. I: Properties of the Corona and the Spectrum of Escaping Radiation

    NASA Technical Reports Server (NTRS)

    Dove, James B.; Wilms, Jorn; Begelman, Mitchell C.

    1997-01-01

    We present the properties of accretion disk corona (ADC) models in which the radiation field, the temperature, and the total opacity of the corona are determined self-consistently. We use a nonlinear Monte Carlo code to perform the calculations. As an example, we discuss models in which the corona is situated above and below a cold accretion disk with a plane-parallel (slab) geometry, similar to the model of Haardt & Maraschi. By Comptonizing the soft radiation emitted by the accretion disk, the corona is responsible for producing the high-energy component of the escaping radiation. Our models include the reprocessing of radiation in the accretion disk. Here the photons either are Compton-reflected or photoabsorbed, giving rise to fluorescent line emission and thermal emission. The self- consistent coronal temperature is determined by balancing heating (due to viscous energy dissipation) with Compton cooling, determined using the fully relativistic, angle-dependent cross sections. The total opacity is found by balancing pair productions with annihilations. We find that, for a disk temperature kT(sub BB) approx. less than 200 eV, these coronae are unable to have a self-consistent temperature higher than approx. 140 keV if the total optical depth is approx. less than 0.2, regardless of the compactness parameter of the corona and the seed opacity. This limitation corresponds to the angle-averaged spectrum of escaping radiation having a photon index approx. greater than 1.8 within the 5-30 keV band. Finally, all models that have reprocessing features also predict a large thermal excess at lower energies. These constraints make explaining the X-ray spectra of persistent black hole candidates with ADC models very problematic.

  3. Design of a compact permanent magnet Cyclotron Mass Spectrometer for the detection and measurement of trace isotopes

    SciTech Connect

    Young, A.T.; Bertsche, K.J.; Clark, D.J.; Halbach, K.; Kunkel, W.B.; Leung, K.N.; Li, C.Y.

    1992-07-01

    A technique for the detection of trace amounts of rare isotopes, Cyclotron mass Spectrometry (CMS), is described. This technique uses the relationships between particle mass, charge, magnetic field strength and cyclotron orbital frequency to provide high mass resolution. The instrument also has high sensitivity and is capable of measuring isotopes with abundances of < 10{sub {minus} 12}. Improvements now being implemented will lead to further increases in the sensitivity and enhance operating parameters such as cost, portability, and sample throughput.

  4. Highly oriented NdFeCoB nanocrystalline magnets from partially disproportionated compacts by reactive deformation under low pressure

    SciTech Connect

    Zheng, Qing; Li, Jun; Liu, Ying Yu, Yunping; Lian, Lixian

    2014-05-07

    In the present investigation, we take advantage of the ultrafine grain size of NdFeCoB partially hydrogen-disproportionated phases, and prepare anisotropic nanocrystalline magnets with full density and homogenous microstructure and texture by reactive deformation under low pressure. Our results suggest that the pressure could properly promote an occurrence of desorption-recombination reaction due to a shorter-range rearrangement of the atoms, and the newly recombined Nd{sub 2}Fe{sub 14}B grains with fine grain size could undergo deformation immediately after the phase transformation, and then an obvious anisotropy and uniform alignment would be obtained. The maximum magnetic properties, (BH){sub max} = 25.8 MGOe, Br = 11.8 kG, H{sub cj} = 5.5 kOe, were obtained after being treated for 5 min at 820 °C in vacuum. The present study highlights the feasibility to prepare anisotropic nanocrystalline magnets with homogeneous microstructure and a strong (00l) texture of uniform grain size under low pressure.

  5. The compact capacitor bank CQ-1.5 employed in magnetically driven isentropic compression and high velocity flyer plate experiments

    NASA Astrophysics Data System (ADS)

    Wang, Guiji; Sun, Chengwei; Tan, Fuli; Zhao, Jianheng; Zhang, Ning; Liu, Cangli; Mo, Jianjun; Wang, Ganghua; Wang, Xiaosong

    2008-05-01

    Based on the low inductance capacitor, the parallel-plate transmission line, and the explosive network closing switch, a compact pulsed power generator CQ-1.5 has been developed at the Institute of Fluid Physics and is capable to deliver a current of peak of 1.5MA within rise time of 500-570ns into a 2-3nH inductive load. The work is motivated to do isentropic compression experiments (ICEs) on metals up to 30-50GPa and to launch flyer plates at velocities over 8km/s. The experiments were conducted with the diagnostics of both Doppler pin system and velocity interferometer system for any reflectors, and the measured free surface velocity histories of ICE samples were treated with a backward integration code. The results show that the isentropes of Cu and Al samples under 35GPa are close to their Hugoniots within a deviation of 3%. The LY12 aluminum flyer plates were accelerated to a velocity over 8.96km/s.

  6. Solid-State Multi-Sensor Array System for Real Time Imaging of Magnetic Fields and Ferrous Objects

    NASA Astrophysics Data System (ADS)

    Benitez, D.; Gaydecki, P.; Quek, S.; Torres, V.

    2008-02-01

    In this paper the development of a solid-state sensors based system for real-time imaging of magnetic fields and ferrous objects is described. The system comprises 1089 magneto inductive solid state sensors arranged in a 2D array matrix of 33×33 files and columns, equally spaced in order to cover an approximate area of 300 by 300 mm. The sensor array is located within a large current-carrying coil. Data is sampled from the sensors by several DSP controlling units and finally streamed to a host computer via a USB 2.0 interface and the image generated and displayed at a rate of 20 frames per minute. The development of the instrumentation has been complemented by extensive numerical modeling of field distribution patterns using boundary element methods. The system was originally intended for deployment in the non-destructive evaluation (NDE) of reinforced concrete. Nevertheless, the system is not only capable of producing real-time, live video images of the metal target embedded within any opaque medium, it also allows the real-time visualization and determination of the magnetic field distribution emitted by either permanent magnets or geometries carrying current. Although this system was initially developed for the NDE arena, it could also have many potential applications in many other fields, including medicine, security, manufacturing, quality assurance and design involving magnetic fields.

  7. CONSTRAINTS ON THE COMPACT OBJECT MASS IN THE ECLIPSING HIGH-MASS X-RAY BINARY XMMU J013236.7+303228 IN M 33

    SciTech Connect

    Bhalerao, Varun B.; Harrison, Fiona A.; Van Kerkwijk, Marten H.

    2012-09-20

    We present optical spectroscopic measurements of the eclipsing high-mass X-ray binary (HMXB) XMMU J013236.7+303228 in M 33. Based on spectra taken at multiple epochs of the 1.73 day binary orbital period we determine physical as well as orbital parameters for the donor star. We find the donor to be a B1.5IV subgiant with effective temperature T = 22, 000-23, 000 K. From the luminosity, temperature, and known distance to M 33 we derive a radius of R 8.9 {+-} 0.5 R{sub Sun }. From the radial-velocity measurements, we determine a velocity semi-amplitude of K{sub opt} = 63 {+-} 12 km s{sup -1}. Using the physical properties of the B star determined from the optical spectrum, we estimate the star's mass to be M{sub opt} = 11 {+-} 1 M{sub Sun }. Based on the X-ray spectrum, the compact companion is likely a neutron star, although no pulsations have yet been detected. Using the spectroscopically derived B star mass we find the neutron star companion mass to be M{sub X} = 2.0 {+-} 0.4 M{sub Sun }, consistent with the neutron star mass in the HMXB Vela X-1, but heavier than the canonical value of 1.4 M{sub Sun} found for many millisecond pulsars. We attempt to use as an additional constraint that the B star radius inferred from temperature, flux, and distance should equate to the Roche radius, since the system accretes by Roche lobe overflow. This leads to substantially larger masses, but by trying to apply the technique to known systems, we find that the masses are consistently overestimated. Attempting to account for that in our uncertainties, we derive M{sub X} = 2.2{sup +0.8}{sub -0.6} M{sub Sun} and M{sub opt} = 13 {+-} 4 M{sub Sun }. We conclude that precise constraints require detailed modeling of the shape of the Roche surface.

  8. Measuring the Kerr spin parameter of a non-Kerr compact object with the continuum-fitting and the iron line methods

    SciTech Connect

    Bambi, Cosimo

    2013-08-01

    Under the assumption that astrophysical black hole candidates are the Kerr black holes of general relativity, the continuum-fitting method and the analysis of the Kα iron line are today the only available techniques capable of providing a relatively reliable estimate of the spin parameter of these objects. If we relax the Kerr black hole hypothesis and we try to test the nature of black hole candidates, we find that there is a strong correlation between the measurement of the spin and possible deviations from the Kerr solution. The properties of the radiation emitted in a Kerr spacetime with spin parameter a{sub *} are indeed very similar, and practically indistinguishable, from the ones of the radiation emitted around a non-Kerr object with different spin. In this paper, I address the question whether measuring the Kerr spin with both the continuum-fitting method and the Kα iron line analysis of the same object can be used to claim the Kerr nature of the black hole candidate in the case of consistent results. In this work, I consider two non-Kerr metrics and it seems that the answer does depend on the specific background. The two techniques may either provide a very similar result (the case of the Bardeen metric) or show a discrepancy (Johannsen-Psaltis background)

  9. Compact orthogonal NMR field sensor

    DOEpatents

    Gerald, II, Rex E.; Rathke, Jerome W.

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  10. Cognitive and anatomical underpinnings of the conceptual knowledge for common objects and familiar people: a repetitive transcranial magnetic stimulation study.

    PubMed

    Campanella, Fabio; Fabbro, Franco; Urgesi, Cosimo

    2013-01-01

    Several studies have addressed the issue of how knowledge of common objects is organized in the brain, whereas the cognitive and anatomical underpinnings of familiar people knowledge have been less explored. Here we applied repetitive transcranial magnetic stimulation (rTMS) over the left and right temporal poles before asking healthy individuals to perform a speeded word-to-picture matching task using familiar people and common objects as stimuli. We manipulated two widely used semantic variables, namely the semantic distance and the familiarity of stimuli, to assess whether the semantic organization of familiar people knowledge is similar to that of common objects. For both objects and faces we reliably found semantic distance and familiarity effects, with less accurate and slower responses for stimulus pairs that were more closely related and less familiar. However, the effects of semantic variables differed across categories, with semantic distance effects larger for objects and familiarity effects larger for faces, suggesting that objects and faces might share a partially comparable organization of their semantic representations. The application of rTMS to the left temporal pole modulated, for both categories, semantic distance, but not familiarity effects, revealing that accessing object and face concepts might rely on overlapping processes within left anterior temporal regions. Crucially, rTMS of the left temporal pole affected only the recognition of pairs of stimuli that could be discriminated at specific levels of categorization (e.g., two kitchen tools or two famous persons), with no effect for discriminations at either superordinate or individual levels. Conversely, rTMS of the right temporal pole induced an overall slowing of reaction times that positively correlated with the visual similarity of the stimuli, suggesting a more perceptual rather than semantic role of the right anterior temporal regions. Results are discussed in the light of current

  11. Cognitive and Anatomical Underpinnings of the Conceptual Knowledge for Common Objects and Familiar People: A Repetitive Transcranial Magnetic Stimulation Study

    PubMed Central

    Campanella, Fabio; Fabbro, Franco; Urgesi, Cosimo

    2013-01-01

    Several studies have addressed the issue of how knowledge of common objects is organized in the brain, whereas the cognitive and anatomical underpinnings of familiar people knowledge have been less explored. Here we applied repetitive transcranial magnetic stimulation (rTMS) over the left and right temporal poles before asking healthy individuals to perform a speeded word-to-picture matching task using familiar people and common objects as stimuli. We manipulated two widely used semantic variables, namely the semantic distance and the familiarity of stimuli, to assess whether the semantic organization of familiar people knowledge is similar to that of common objects. For both objects and faces we reliably found semantic distance and familiarity effects, with less accurate and slower responses for stimulus pairs that were more closely related and less familiar. However, the effects of semantic variables differed across categories, with semantic distance effects larger for objects and familiarity effects larger for faces, suggesting that objects and faces might share a partially comparable organization of their semantic representations. The application of rTMS to the left temporal pole modulated, for both categories, semantic distance, but not familiarity effects, revealing that accessing object and face concepts might rely on overlapping processes within left anterior temporal regions. Crucially, rTMS of the left temporal pole affected only the recognition of pairs of stimuli that could be discriminated at specific levels of categorization (e.g., two kitchen tools or two famous persons), with no effect for discriminations at either superordinate or individual levels. Conversely, rTMS of the right temporal pole induced an overall slowing of reaction times that positively correlated with the visual similarity of the stimuli, suggesting a more perceptual rather than semantic role of the right anterior temporal regions. Results are discussed in the light of current

  12. Ureilite compaction

    NASA Astrophysics Data System (ADS)

    Walker, D.; Agee, C. B.

    1988-03-01

    Ureilite meteorites show the simple mineralogy and compact recrystallized textures of adcumulate rock or melting residues. A certain amount of controversy exists about whether they are in fact adcumulate rocks or melting residues and about the nature of the precursor liquid or solid assemblage. The authors undertook a limited experimental study which made possible the evaluation of the potential of the thermal migration mechanism (diffusion on a saturation gradient) for forming ureilite-like aggregates from carbonaceous chondrite precursors. They find that the process can produce compact recrystallized aggregates of silicate crystals which do resemble the ureilities and other interstitial-liquid-free adcumulate rocks in texture.

  13. Embedding inertial-magnetic sensors in everyday objects: Assessing spatial cognition in children

    PubMed Central

    Taffoni, Fabrizio; Formica, Domenico; Iverson, Jana; Sparaci, Laura; Keller, Flavio; Guglielmelli, Eugenio

    2013-01-01

    This paper describes an interdisciplinary approach to the assessment of children development of spatial cognition, with a focus on the technology. An instrumented toy (block-box) is presented which embeds magneto-inertial sensors for orientation tracking, specifically developed to assess the ability to insert objects into holes. The functional specifications are derived from experimental protocols devised by neuroscientists to assess spatial cognition skills in children. Technological choices are emphasized with respect to ecological requirements. Ad-hoc calibration procedures are presented which are suitable to unstructured environments. Preliminary results based on experimental trials carried out at a day-care on typically developing children (12–36 months old) show how the instrumented objects can be used effectively in a semi-automatic fashion (i.e., rater-independent) to derive accurate measurements such as orientation errors and insertion time which are relevant to the object insertion task. This study indicates that a technological approach to ecological assessment of spatial cognition in children is indeed feasible and maybe useful for identification and early assessment of developmental delay. PMID:22744786

  14. Magnetically Driven Jets from Accretion Disks. I. Steady Solutions and Application to Jets/Winds in Young Stellar Objects

    NASA Astrophysics Data System (ADS)

    Kudoh, Takahiro; Shibata, Kazunari

    1997-01-01

    We solve one-dimensional steady and axisymmetric magnetohydrodynamic (MHD) equations to study basic properties of astrophysical jets from accretion disks. Assuming the configuration of the poloidal magnetic field, we solve for a wide range of parameters of the poloidal magnetic field strength in the disk. We include a thermal energy in the solution, although the jet is mainly accelerated by the magnetic force, so that we are able to obtain the mass flux of the jet and physical quantities, such as temperature, in the disk. We find that the mass flux (Ṁ) depends on the poloidal magnetic field strength of the disk (Bp0) when the toroidal component of the magnetic field (Bφ0) is dominant near the disk surface, although it is independent of the magnetic field when the poloidal component is dominant there:Ṁ~const,if |Bφ/Bp|0<<1,Bp0,if |Bφ/Bp|0>>1. Since Michel's minimum energy solution [v∞~(B2p0/Ṁ)1/3] is almost satisfied in the magnetically driven jets, the terminal velocity (v∞) depends on Bp0 as v∞~B1/3p0 when | Bφ/Bp |0 >> 1, and as v∞~B2/3p0 when | Bφ/Bp |0 << 1. When the toroidal component of the magnetic field is dominant near the disk surface (| Bφ/Bp |0 >> 1), the acceleration mainly takes place after the flow speed exceeds the Alfvén speed. This means that the magnetic pressure largely contributes to the acceleration of these jets. We also study the dependence of mass flux on the other parameters, such as inclination angle of the poloidal field, the rotational velocity of the disk, and the r-dependence of the poloidal magnetic field strength along the field line, where r is the distance from the axis. We discuss the application of these models, i.e., the MHD jets from accretion disks, to jets/winds observed in young stellar objects (such as optical jets, T Tauri winds, and fast neutral winds). The mass-loss rates observed in these jets/winds will constrain the physical quantities in the disks. When the mass-loss rate is Ṁ~10-8 M⊙ yr-1

  15. Multicomponent Theory of Buoyancy Instabilities in Astrophysical Plasma Objects: The Case of Magnetic Field Perpendicular to Gravity

    NASA Astrophysics Data System (ADS)

    Nekrasov, Anatoly K.; Shadmehri, Mohsen

    2010-12-01

    We develop a general theory of buoyancy instabilities in the electron-ion plasma with the electron heat flux based not upon magnetohydrodynamic (MHD) equations, but using a multicomponent plasma approach in which the momentum equation is solved for each species. We investigate the geometry in which the background magnetic field is perpendicular to the gravity and stratification. General expressions for the perturbed velocities are given without any simplifications. Collisions between electrons and ions are taken into account in the momentum equations in a general form, permitting us to consider both weakly and strongly collisional objects. However, the electron heat flux is assumed to be directed along the magnetic field, which implies a weakly collisional case. Using simplifications justified for an investigation of buoyancy instabilities with electron thermal flux, we derive simple dispersion relations for both collisionless and collisional cases for arbitrary directions of the wave vector. Our dispersion relations considerably differ from that obtained in the MHD framework and conditions of instability are similar to Schwarzschild's criterion. This difference is connected with simplified assumptions used in the MHD analysis of buoyancy instabilities and with the role of the longitudinal electric field perturbation which is not captured by the ideal MHD equations. The results obtained can be applied to clusters of galaxies and other astrophysical objects.

  16. Directional location of buried objects using three component magnetic borehole data demonstrated for the case of a drillstring

    NASA Astrophysics Data System (ADS)

    Ehmann, S.; Virgil, C.; Hördt, A.; Leven, M.

    2016-04-01

    One of the main applications of magnetic field measurements in boreholes is the detection of unexploded ordnance or buried utility structures like pipes or tiebacks. Even though the advantage of fully oriented magnetic vector measurements have long been recognised and could significantly reduce costs and risks, the tools used for those purposes typically measure only the total magnetic field, the vertical and horizontal components or gradients thereof. The Göttingen Bohrloch Magnetometer (GBM) uses three fiber optic gyros to record its orientation and thus enables us to compute high quality three component magnetic vector data regardless of borehole orientation. The measurements described in this paper were run in the scientific borehole Cuxhaven Lüdingworth 1/1A, which was drilled as a part of the "Coastal Aquifer Test field" project to study the dynamics of the saltwater/freshwater interface. As the drillstring got stuck during drilling of the first borehole, a second hole was drilled in the immediate vicinity. The drillstring lies at a depth between 80 m and 114 m at a distance of only 2.5 m south-east of the borehole used for the measurements, making it an ideal target to demonstrate the benefits of vector magnetic surveys. Although the theories to calculate magnetic fields of objects with different shapes is well established and do not need to be tested, they almost exclusively include approximations of the geometry. It is not obvious whether these approximations are suited to describe real data, or whether additional effects or refinements have to be considered. We use both a simplified monopole model and a cylinder model to fit the data and are able to determine the position of the drillstring within a statistical error of approximately 10 cm. Additionally, we show that the location of the drillstring could not have been determined by measurements of the total field or its horizontal and vertical component alone and that those methods would require the

  17. Magnetic Gradient Horizontal Operator (MHGO) useful for detecting objects buried at shallow depth: cultural heritage (Villa degli Antonini, Rota Rio)

    NASA Astrophysics Data System (ADS)

    Di Filippo, Michele; Di Nezza, Maria

    2016-04-01

    Several factors were taken into consideration in order to appropriately tailor the geophysical explorations at the cultural heritage. Given the fact that each site has been neglected for a long time and in recent times used as an illegal dumping area, we thoroughly evaluated for this investigation the advantages and limitations of each specific technique, and the general conditions and history of the site. We took into account the extension of the areas to be investigated and the need for rapid data acquisition and processing. Furthermore, the survey required instrumentation with sensitivity to small background contrasts and as little as possible affected by background noise sources. In order to ascertain the existence and location of underground buried walls, a magnetic gradiometer survey (MAG) was planned. The map of the magnetic anomalies is not computed to reduction at the pole (RTP), but with a magnetic horizontal gradient operator (MHGO). The magnetic horizontal gradient operator (MHGO) generates from a grid of vertical gradient a grid of steepest slopes (i.e. the magnitude of the gradient) at any point on the surface. The MHGO is reported as a number (rise over run) rather than degrees, and the direction is opposite to that of the slope. The MHGO is zero for a horizontal surface, and approaches infinity as the slope approaches the vertical. The gradient data are especially useful for detecting objects buried at shallow depth. The map reveals some details of the anomalies of the geomagnetic field. Magnetic anomalies due to walls are more evident than in the total intensity map, whereas anomalies due to concentrations of debris are very weak. In this work we describe the results of an investigation obtained with magnetometry investigation for two archaeological sites: "Villa degli Antonini" (Genzano, Rome) and Rota Ria (Mugnano in Teverina, Viterbo). Since the main goal of the investigation was to understand the nature of magnetic anomalies with cost

  18. Directional location of buried objects using three-component magnetic borehole data demonstrated for the case of a drill string

    NASA Astrophysics Data System (ADS)

    Ehmann, S.; Virgil, C.; Hördt, A.; Leven, M.

    2016-06-01

    One of the main applications of magnetic field measurements in boreholes is the detection of unexploded ordnance or buried utility structures like pipes or tiebacks. Even though the advantage of fully oriented magnetic vector measurements have long been recognized and could significantly reduce costs and risks, the tools used for those purposes typically measure only the total magnetic field, the vertical and horizontal components or gradients thereof. The Göttingen Bohrloch Magnetometer uses three fibre optic gyros to record its orientation and thus enables us to compute high-quality three-component magnetic vector data regardless of borehole orientation. The measurements described in this paper were run in the scientific borehole Cuxhaven Lüdingworth 1/1A, which was drilled as a part of the `Coastal Aquifer Test field' project to study the dynamics of the saltwater/freshwater interface. As the drill string got stuck during drilling of the first borehole, a second hole was drilled in the immediate vicinity. The drill string lies at a depth between 80 and 114 m at a distance of only 2.5 m southeast of the borehole used for the measurements, making it an ideal target to demonstrate the benefits of vector magnetic surveys. Although the theories to calculate magnetic fields of objects with different shapes is well established and do not need to be tested, they almost exclusively include approximations of the geometry. It is not obvious whether these approximations are suited to describe real data, or whether additional effects or refinements have to be considered. We use both a simplified monopole model and a cylinder model to fit the data and are able to determine the position of the drill string within a statistical error of approximately 10 cm. Additionally, we show that the location of the drill string could not have been determined by measurements of the total field or its horizontal and vertical component alone and that those methods would require the drilling

  19. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    SciTech Connect

    Prodan, Snezana; Antonini, Fabio; Perets, Hagai B. E-mail: antonini@cita.utoronto.ca

    2015-02-01

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center.

  20. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  1. Object Representations in the Temporal Cortex of Monkeys and Humans as Revealed by Functional Magnetic Resonance Imaging

    PubMed Central

    Bell, Andrew H.; Hadj-Bouziane, Fadila; Frihauf, Jennifer B.; Tootell, Roger B. H.; Ungerleider, Leslie G.

    2009-01-01

    Increasing evidence suggests that the neural processes associated with identifying everyday stimuli include the classification of those stimuli into a limited number of semantic categories. How the neural representations of these stimuli are organized in the temporal lobe remains under debate. Here we used functional magnetic resonance imaging (fMRI) to identify correlates for three current hypotheses concerning object representations in the inferior temporal (IT) cortex of monkeys and humans: representations based on animacy, semantic categories, or visual features. Subjects were presented with blocked images of faces, body parts (animate stimuli), objects, and places (inanimate stimuli), and multiple overlapping contrasts were used to identify the voxels most selective for each category. Stimulus representations appeared to segregate according to semantic relationships. Discrete regions selective for animate and inanimate stimuli were found in both species. These regions could be further subdivided into regions selective for individual categories. Notably, face-selective regions were contiguous with body-part-selective regions, and object-selective regions were contiguous with place-selective regions. When category-selective regions in monkeys were tested with blocks of single exemplars, individual voxels showed preferences for visually dissimilar exemplars from the same category and voxels with similar preferences tended to cluster together. Our results provide some novel observations with respect to how stimulus representations are organized in IT cortex. In addition, they further support the idea that representations of complex stimuli in IT cortex are organized into multiple hierarchical tiers, encompassing both semantic and physical properties. PMID:19052111

  2. Compact Spreader Schemes

    SciTech Connect

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  3. Radiatively driven plasma jets around compact objects

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Indranil; Chakrabarti, Sandip K.

    2002-06-01

    Matter accreting on to black holes may develop shocks due to the centrifugal barrier. Some of the inflowing matter in the post-shock flow is deflected along the axis in the form of jets. Post-shock flow which behaves like a Compton cloud has `hot' electrons emitting high-energy photons. We study the effect of these `hot' photons on the outflowing matter. Radiation from this region could accelerate the outflowing matter, but radiation pressure should also slow it down. We show that the radiation drag restricts the flow from attaining a very high velocity. We introduce the concept of an `equilibrium velocity' (veq~0.5c), which sets the upper limit of the terminal velocity achieved by a cold plasma due to radiation deposition force in the absence of gravity. If the injection energy is Ein, then we find that the terminal velocity v∞ satisfies a relation v2<~veq2+2Ein.

  4. Neural correlates of conceptual object priming in young and older adults: an event-related functional magnetic resonance imaging study.

    PubMed

    Ballesteros, Soledad; Bischof, Gérard N; Goh, Joshua O; Park, Denise C

    2013-04-01

    In this event-related functional magnetic resonance imaging study, we investigated age-related differences in brain activity associated with conceptual repetition priming in young and older adults. Participants performed a speeded "living/nonliving" classification task with 3 repetitions of familiar objects. Both young and older adults showed a similar magnitude of behavioral priming to repeated objects and evidenced repetition-related activation reductions in fusiform gyrus, superior occipital, middle, and inferior temporal cortex, and inferior frontal and insula regions. The neural priming effect in young adults was extensive and continued through both the second and third stimulus repetitions, and neural priming in older adults was markedly attenuated and reached floor at the second repetition. In young adults, greater neural priming in multiple brain regions correlated with greater behavioral facilitation and in older adults, only activation reduction in the left inferior frontal correlated with faster behavioral responses. These findings provide evidence for altered neural priming in older adults despite preserved behavioral priming, and suggest the possibility that age-invariant behavioral priming is observed as a result of more sustained neural processing of stimuli in older adults which might be a form of compensatory neural activity. PMID:23102512

  5. Arthroscopic verification of objectivity of the orthopaedic examination and magnetic resonance imaging in intra-articular knee injury. Retrospective study

    PubMed Central

    Skowronek, Michał; Skowronek, Paweł; Dutka, Łukasz

    2011-01-01

    Introduction Arthroscopy of the knee joint is regarded as the most objective diagnostic method in intra-articular knee joint lesions. Aim The purpose of this study was to assess the objectivity and diagnostic value of orthopaedic examination (OE) and magnetic resonance imaging (MRI) in reference to the arthroscopic result. Material and methods In a group of 113 patients treated by arthroscopic surgery for post-traumatic knee pathology between 2008 and 2010 in our department, accuracy of clinical and MRI findings that preceded surgery were studied retrospectively using a statistical method. Sensitivity, specificity, accuracy and predictive negative and positive values were the subject of analysis. Results In the presented trial, sensitivity values of the orthopaedic examination for injuries of the anterior cruciate ligament (ACL), meniscus medialis (MM), meniscus lateralis (ML) and chondral injuries (ChI) were 86%, 65%, 38% and 51%, respectively. Specificity values were 90%, 65%, 100% and 100%, respectively. The MR sensitivity and specificity values were 80%, 88%, 44% and 32%, and 86%, 64%, 93% and 97%, respectively. Conclusions Assessment of intra-articular knee joint lesions is a difficult diagnostic problem. In making a decision about arthroscopy of the knee joint, an appropriate sequence of examinations should be carried out: OE, MRI and arthroscopy. The improvement in the effectiveness of the orthopaedic examination and MRI can limit the too high frequency of diagnostic arthroscopies, which generates the risk of operation treatment and costs. PMID:23255995

  6. Compact LINAC for deuterons

    SciTech Connect

    Kurennoy, S S; O' Hara, J F; Rybarcyk, L J

    2008-01-01

    We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

  7. Magnetic Phases in Dense Quark Matter

    SciTech Connect

    Incera, Vivian de la

    2007-10-26

    In this paper I discuss the magnetic phases of the three-flavor color superconductor. These phases can take place at different field strengths in a highly dense quark system. Given that the best natural candidates for the realization of color superconductivity are the extremely dense cores of neutron stars, which typically have very large magnetic fields, the magnetic phases here discussed could have implications for the physics of these compact objects.

  8. Magnetic Field Generation in Stars

    NASA Astrophysics Data System (ADS)

    Ferrario, Lilia; Melatos, Andrew; Zrake, Jonathan

    2015-10-01

    Enormous progress has been made on observing stellar magnetism in stars from the main sequence (particularly thanks to the MiMeS, MAGORI and BOB surveys) through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence, in the generation and stability of neutron star fields.

  9. Steady state compact toroidal plasma production

    DOEpatents

    Turner, William C.

    1986-01-01

    Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

  10. Cortical distribution of speech and language errors investigated by visual object naming and navigated transcranial magnetic stimulation.

    PubMed

    Krieg, Sandro M; Sollmann, Nico; Tanigawa, Noriko; Foerschler, Annette; Meyer, Bernhard; Ringel, Florian

    2016-05-01

    Navigated transcranial magnetic stimulation (nTMS) gains increasing importance in presurgical language mapping. Although bipolar direct cortical stimulation (DCS) is regarded as the gold standard for intraoperative mapping of language-related areas, it cannot be used to map the healthy human brain due to its invasive character. Therefore, the present study employed a non-invasive virtual-lesion modality to provide a causality-confirmed cortical language map of the healthy human brain by repetitive nTMS (rTMS) with functional specifications beyond language-positive/language-negative distinction. Fifty right-handed healthy volunteers underwent rTMS language mapping of the left hemisphere combined with an object-naming task. The induced errors were categorized and frequency maps were calculated. Moreover, a principal component analysis (PCA) was performed on the basis of language-positive cortical regions for each error category. The left hemisphere was stimulated at 258-789 sites (median: 361.5 sites), and 12-241 naming errors (median: 72.5 errors) were observed. In male subjects, a total number of 2091 language errors were elicited by 9579 stimulation trains, which is equal to an error rate of 21.8 %. Within females, 10,238 stimulation trains elicited 2032 language errors (19.8 %). PCA revealed that the inferior parietal lobe (IPL) and middle frontal gyrus (MFG) were causally involved in object naming as a semantic center and an executive control center. For the first time, this study provides causality-based data and a model that approximates the distribution of language-related cortical areas grouped for different functional aspects of single-word production processes by PCA. PMID:25894631

  11. Compact accelerator for medical therapy

    DOEpatents

    Caporaso, George J.; Chen, Yu-Jiuan; Hawkins, Steven A.; Sampayan, Stephen E.; Paul, Arthur C.

    2010-05-04

    A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (.about.70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.

  12. Compaction behavior of roller compacted ibuprofen.

    PubMed

    Patel, Sarsvatkumar; Kaushal, Aditya Mohan; Bansal, Arvind Kumar

    2008-06-01

    The effect of roller compaction pressure on the bulk compaction of roller compacted ibuprofen was investigated using instrumented rotary tablet press. Three different roller pressures were utilized to prepare granules and Heckel analysis, Walker analysis, compressibility, and tabletability were performed to derive densification, deformation, course of volume reduction and bonding phenomenon of different pressure roller compacted granules. Nominal single granule fracture strength was obtained by micro tensile testing. Heckel analysis indicated that granules prepared using lower pressure during roller compaction showed lower yield strength. The reduction in tabletability was observed for higher pressure roller compacted granules. The reduction in tabletability supports the results of granule size enlargement theory. Apart from the granule size enlargement theory, the available fines and relative fragmentation during compaction is responsible for higher bonding strength and provide larger areas for true particle contact at constant porosity for lower pressure roller compacted granules. Overall bulk compaction parameters indicated that granules prepared by lower roller compaction pressure were advantageous in terms of tabletability and densification. Overall results suggested that densification during roller compaction affects the particle level properties of specific surface area, nominal fracture strength, and compaction behavior. PMID:18280716

  13. Compact Reactor

    SciTech Connect

    Williams, Pharis E.

    2007-01-30

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date.

  14. Compact multiframe blind deconvolution.

    PubMed

    Hope, Douglas A; Jefferies, Stuart M

    2011-03-15

    We describe a multiframe blind deconvolution (MFBD) algorithm that uses spectral ratios (the ratio of the Fourier spectra of two data frames) to model the inherent temporal signatures encoded by the observed images. In addition, by focusing on the separation of the object spectrum and system transfer functions only at spatial frequencies where the measured signal is above the noise level, we significantly reduce the number of unknowns to be determined. This "compact" MFBD yields high-quality restorations in a much shorter time than is achieved with MFBD algorithms that do not model the temporal signatures; it may also provide higher-fidelity solutions. PMID:21403711

  15. A linear actuator for precision positioning of dual objects

    NASA Astrophysics Data System (ADS)

    Peng, Yuxin; Cao, Jie; Guo, Zhao; Yu, Haoyong

    2015-12-01

    In this paper, a linear actuator for precision positioning of dual objects is proposed based on a double friction drive principle using a single piezoelectric element (PZT). The linear actuator consists of an electromagnet and a permanent magnet, which are connected by the PZT. The electromagnet serves as an object 1, and another object (object 2) is attached on the permanent magnet by the magnetic force. For positioning the dual objects independently, two different friction drive modes can be alternated by an on-off control of the electromagnet. When the electromagnet releases from the guide way, it can be driven by impact friction force generated by the PZT. Otherwise, when the electromagnet clamps on the guide way and remains stationary, the object 2 can be driven based on the principle of smooth impact friction drive. A prototype was designed and constructed and experiments were carried out to test the basic performance of the actuator. It has been verified that with a compact size of 31 mm (L) × 12 mm (W) × 8 mm (H), the two objects can achieve long strokes on the order of several millimeters and high resolutions of several tens of nanometers. Since the proposed actuator allows independent movement of two objects by a single PZT, the actuator has the potential to be constructed compactly.

  16. Formation of a compact toroid for enhanced efficiency

    SciTech Connect

    Mozgovoy, A. G.; Romadanov, I. V.; Ryzhkov, S. V.

    2014-02-15

    We report here our results on the formation of a plasma configuration with the generic name of compact toroid (CT). A method of compact toroid formation to confine, heat and compress a plasma is investigated. Formation of a compact torus using an additional toroidal magnetic field helps to increase the plasma current to a maintainable level of the original magnetic field. We design the Compact Toroid Challenge (CTC) experiment in order to improve the magnetic flux trapping during field reversal in the formation of a compact toroid. The level of the magnetic field immersed in the plasma about 70% of the primary field is achieved. The CTC device and scheme of high level capturing of magnetic flux are presented.

  17. Formation of a compact toroid for enhanced efficiency

    NASA Astrophysics Data System (ADS)

    Mozgovoy, A. G.; Romadanov, I. V.; Ryzhkov, S. V.

    2014-02-01

    We report here our results on the formation of a plasma configuration with the generic name of compact toroid (CT). A method of compact toroid formation to confine, heat and compress a plasma is investigated. Formation of a compact torus using an additional toroidal magnetic field helps to increase the plasma current to a maintainable level of the original magnetic field. We design the Compact Toroid Challenge (CTC) experiment in order to improve the magnetic flux trapping during field reversal in the formation of a compact toroid. The level of the magnetic field immersed in the plasma about 70% of the primary field is achieved. The CTC device and scheme of high level capturing of magnetic flux are presented.

  18. Nuclear Physics for Compact Stars

    SciTech Connect

    Baldo, M.

    2009-05-04

    A brief overview is given of the different lines of research developed under the INFN project 'Compact Stellar Objects and Dense Hadronic Matter' (acronym CT51). The emphasis of the project is on the structure of Neutron Stars (NS) and related objects. Starting from crust, the different Nuclear Physics problems are described which are encountered going inside a NS down to its inner core. The theoretical challenges and the observational inputs are discussed in some detail.

  19. Preliminary results of simulation of hypo magnetic conditions and variations in energetic range of cosmic rays in ground-based experiments on plant objects

    NASA Astrophysics Data System (ADS)

    Belisheva, Natalia; Petrashova, Dina; Shchegolev, Boris

    The most dangerous for the astronauts and cosmonauts are the cosmic rays and drastic decrease of the tension of geomagnetic field (GMF) on the Earth orbit and in the open space. The tension in the interplanetary magnetic field is 10 nT, whereas the tension of GMF is 10 (4) nT on the Earth surface. We carried out the preliminary experiments for study the effects of hypo magnetic conditions and variations in energetic range of cosmic rays (CR) on the plant objects (Vigna radiata, Phaseolus vulgaris, Allium cepa and A. fistulosum, Cucumis sativis). GMF was weakened by using special shielding chamber made on the basis of the amorphous alloy magnetic material. The camera is able to weaken the GMF from 48 μT till 0.192 μT. Modulation of the energetic range of the neutron component of secondary CR was performed with using of the shielding by graphite and by paraffin. The influence of hypo magnetic field and the neutron intensity were studied on the germination of seeds, the growth, the length and the side branches of the roots in the experimental samples. We found that the sensitivity to the hypo magnetic field and to the variations in energetic range of neutrons can vary from object to object. For instance, exposure of the hypo magnetic field on black bean and mung bean stimulated the growth of the roots while do not affect on the white bean. Likewise sensitivity of Phaseolus vulgaris (black and white bean) and Vigna radiata (mung bean) to exposure of nucleon component of cosmic rays on the Earth's surface are differed. It was found that modification of energetic range of CR by using graphite shielding leads to a change in sign of correlation between the length of roots in all experimental samples and the nucleon component of CR compared with the control samples. This is evidence that physiology of biological objects significantly are modified in hypo magnetic environment, as well as under exposure of the CR in different energetic ranges during the space flights. Our

  20. Object Oriented Learning Objects

    ERIC Educational Resources Information Center

    Morris, Ed

    2005-01-01

    We apply the object oriented software engineering (OOSE) design methodology for software objects (SOs) to learning objects (LOs). OOSE extends and refines design principles for authoring dynamic reusable LOs. Our learning object class (LOC) is a template from which individualised LOs can be dynamically created for, or by, students. The properties…

  1. Recovery from Object Substitution Masking Induced by Transient Suppression of Visual Motion Processing: A Repetitive Transcranial Magnetic Stimulation Study

    ERIC Educational Resources Information Center

    Hirose, Nobuyuki; Kihara, Ken; Mima, Tatsuya; Ueki, Yoshino; Fukuyama, Hidenao; Osaka, Naoyuki

    2007-01-01

    Object substitution masking is a form of visual backward masking in which a briefly presented target is rendered invisible by a lingering mask that is too sparse to produce lower image-level interference. Recent studies suggested the importance of an updating process in a higher object-level representation, which should rely on the processing of…

  2. Numerical analysis of applied magnetic field dependence in Malmberg-Penning Trap for compact simulator of energy driver in heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Sato, T.; Park, Y.; Soga, Y.; Takahashi, K.; Sasaki, T.; Kikuchi, T.; Harada, Nob

    2016-05-01

    To simulate a pulse compression process of space charge dominated beams in heavy ion fusion, we have demonstrated a multi-particle numerical simulation as an equivalent beam using the Malmberg-Penning trap device. The results show that both transverse and longitudinal velocities as a function of external magnetic field strength are increasing during the longitudinal compression. The influence of space-charge effect, which is related to the external magnetic field, was observed as the increase of high velocity particles at the weak external magnetic field.

  3. Improvement in Paretic Arm Reach-to-Grasp following Low Frequency Repetitive Transcranial Magnetic Stimulation Depends on Object Size: A Pilot Study

    PubMed Central

    Tretriluxana, Jarugool; Kantak, Shailesh; Tretriluxana, Suradej; Wu, Allan D.; Fisher, Beth E.

    2015-01-01

    Introduction. Low frequency repetitive transcranial magnetic stimulation (LF-rTMS) delivered to the nonlesioned hemisphere has been shown to improve limited function of the paretic upper extremity (UE) following stroke. The outcome measures have largely included clinical assessments with little investigation on changes in kinematics and coordination. To date, there is no study investigating how the effects of LF-rTMS are modulated by the sizes of an object to be grasped. Objective. To investigate the effect of LF-rTMS on kinematics and coordination of the paretic hand reach-to-grasp (RTG) for two object sizes in chronic stroke. Methods. Nine participants received two TMS conditions: real rTMS and sham rTMS conditions. Before and after the rTMS conditions, cortico-motor excitability (CE) of the nonlesioned hemisphere, RTG kinematics, and coordination was evaluated. Object sizes were 1.2 and 7.2 cm in diameter. Results. Compared to sham rTMS, real rTMS significantly reduced CE of the non-lesioned M1. While rTMS had no effect on RTG action for the larger object, real rTMS significantly improved movement time, aperture opening, and RTG coordination for the smaller object. Conclusions. LF-rTMS improves RTG action for only the smaller object in chronic stroke. The findings suggest a dissociation between effects of rTMS on M1 and task difficulty for this complex skill. PMID:26664827

  4. Feasibility of using high temperature superconducting magnets and conventional magnetic loop antennas to attract or repel objects at the space station

    NASA Astrophysics Data System (ADS)

    Randhawa, Manjit S.

    1989-02-01

    A study was undertaken to see if magnetic forces can be used at the Space Station to attract or repel spacecrafts such as the Orbital Manuevering Vehicle (OMV) or the Orbiter. A large magnet, in the form of a current loop, is assumed to be placed at the Space Station and another one on the spacecraft. The expression for the force between the two dipoles (loops) is obtained. Using a force of 15 Newtons (3.4 pounds) in order to move the spacecraft, the number of ampere-turn needed in the current loops was calculated at various distances between them. The expression for the force of attraction between a current loop and a soft magnetic material was also examined and the number of amp-turn needed to provide a force of one-tenth of a pound at various distances is also calculated. This one tenth of a pound force would be used in a life line system for the retrieval of an adrift crewman or tool at the Space Station. The feasibility of using conventional antenna on the Station and the incoming vehicle for attraction or repulsion was also examined.

  5. Feasibility of using high temperature superconducting magnets and conventional magnetic loop antennas to attract or repel objects at the space station

    NASA Technical Reports Server (NTRS)

    Randhawa, Manjit S.

    1989-01-01

    A study was undertaken to see if magnetic forces can be used at the Space Station to attract or repel spacecrafts such as the Orbital Manuevering Vehicle (OMV) or the Orbiter. A large magnet, in the form of a current loop, is assumed to be placed at the Space Station and another one on the spacecraft. The expression for the force between the two dipoles (loops) is obtained. Using a force of 15 Newtons (3.4 pounds) in order to move the spacecraft, the number of ampere-turn needed in the current loops was calculated at various distances between them. The expression for the force of attraction between a current loop and a soft magnetic material was also examined and the number of amp-turn needed to provide a force of one-tenth of a pound at various distances is also calculated. This one tenth of a pound force would be used in a life line system for the retrieval of an adrift crewman or tool at the Space Station. The feasibility of using conventional antenna on the Station and the incoming vehicle for attraction or repulsion was also examined.

  6. Effects of relative density on microwave heating of various carbon powder compacts microwave-metallic multi-particle coupling using spatially separated magnetic fields

    NASA Astrophysics Data System (ADS)

    Kashimura, K.; Hasegawa, N.; Suzuki, S.; Hayashi, M.; Mitani, T.; Shinohara, N.; Nagata, K.

    2013-01-01

    We have investigated the microwave heating characteristics of non-magnetic conductive multi-particle systems using spatially separated electric and magnetic fields (Emax and Hmax, respectively) to determine the effects of the multi-particle structure on microwave heating. Pure carbon, carbon black, and artificial graphite multi-particle systems exhibited peak microwave absorption at specific relative densities only under Hmax. These absorptions can be categorized into two types: one originates from coupling between metal spheres, while the other originates from a heterogeneous distribution of particles.

  7. Mouse Embryo Compaction.

    PubMed

    White, M D; Bissiere, S; Alvarez, Y D; Plachta, N

    2016-01-01

    Compaction is a critical first morphological event in the preimplantation development of the mammalian embryo. Characterized by the transformation of the embryo from a loose cluster of spherical cells into a tightly packed mass, compaction is a key step in the establishment of the first tissue-like structures of the embryo. Although early investigation of the mechanisms driving compaction implicated changes in cell-cell adhesion, recent work has identified essential roles for cortical tension and a compaction-specific class of filopodia. During the transition from 8 to 16 cells, as the embryo is compacting, it must also make fundamental decisions regarding cell position, polarity, and fate. Understanding how these and other processes are integrated with compaction requires further investigation. Emerging imaging-based techniques that enable quantitative analysis from the level of cell-cell interactions down to the level of individual regulatory molecules will provide a greater understanding of how compaction shapes the early mammalian embryo. PMID:27475854

  8. Design and Integration of an All-Magnetic Attitude Control System for FASTSAT-HSV01's Multiple Pointing Objectives

    NASA Technical Reports Server (NTRS)

    DeKock, Brandon; Sanders, Devon; Vanzwieten, Tannen; Capo-Lugo, Pedro

    2011-01-01

    The FASTSAT-HSV01 spacecraft is a microsatellite with magnetic torque rods as it sole attitude control actuator. FASTSAT s multiple payloads and mission functions require the Attitude Control System (ACS) to maintain Local Vertical Local Horizontal (LVLH)-referenced attitudes without spin-stabilization, while the pointing errors for some attitudes be significantly smaller than the previous best-demonstrated for this type of control system. The mission requires the ACS to hold multiple stable, unstable, and non-equilibrium attitudes, as well as eject a 3U CubeSat from an onboard P-POD and recover from the ensuing tumble. This paper describes the Attitude Control System, the reasons for design choices, how the ACS integrates with the rest of the spacecraft, and gives recommendations for potential future applications of the work.

  9. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1988-05-23

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

  10. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, Vance A.; Ward, Michael B.

    1989-01-01

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

  11. Compact Doppler magnetograph

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, Alexander; Moynihan, Philip I.; Vaughan, Arthur H.; Cacciani, Alessandro

    1998-11-01

    We designed a low-cost flight instrument that images the full solar disk through two narrow band filters at the red nd blue 'wings' of the solar potassium absorption line. The images are produced on a 1024 X 1024 charge-coupled device with a resolution of 2 arcsec per pixel. Four filtergrams taken in a very short time at both wings in the left and right states of circular polarization are used to yield a Dopplergram and a magnetogram simultaneously. The noise-equivalent velocity associated with each pixel is less than 3 m/s. The measured signal is linearly proportional to the velocity in the range +/- 4000 m/s. The range of magnetic fields is from 3 to 3000 Gauss. The optical system of the instrument is simple and easily aligned. With a pixel size of 12 micrometers , the effective focal length is 126 cm. A Raleigh resolution limit of 4 arcsec is achieved with a 5-cm entrance apertures, providing an f/25 focal ratio. The foreoptic is a two-component telephoto lens serving to limit the overall optical length to 89 cm or less. The mass of the instrument is 14 kg. the power required is less than 30 Watts. The Compact Doppler Magnetograph can be used in space mission with severe mass and power requirements. It can also be effectively used for ground-based observations: large telescope, dome or other observatory facilities are not required.

  12. Reversible DNA compaction.

    PubMed

    González-Pérez, Alfredo

    2014-01-01

    In this review we summarize and discuss the different methods we can use to achieve reversible DNA compaction in vitro. Reversible DNA compaction is a natural process that occurs in living cells and viruses. As a result these process long sequences of DNA can be concentrated in a small volume (compacted) to be decompacted only when the information carried by the DNA is needed. In the current work we review the main artificial compacting agents looking at their suitability for decompaction. The different approaches used for decompaction are strongly influenced by the nature of the compacting agent that determines the mechanism of compaction. We focus our discussion on two main artificial compacting agents: multivalent cations and cationic surfactants that are the best known compacting agents. The reversibility of the process can be achieved by adding chemicals like divalent cations, alcohols, anionic surfactants, cyclodextrins or by changing the chemical nature of the compacting agents via pH modifications, light induced conformation changes or by redox-reactions. We stress the relevance of electrostatic interactions and self-assembly as a main approach in order to tune up the DNA conformation in order to create an on-off switch allowing a transition between coil and compact states. The recent advances to control DNA conformation in vitro, by means of molecular self-assembly, result in a better understanding of the fundamental aspects involved in the DNA behavior in vivo and serve of invaluable inspiration for the development of potential biomedical applications. PMID:24444152

  13. Compact Dexterous Robotic Hand

    NASA Technical Reports Server (NTRS)

    Lovchik, Christopher Scott (Inventor); Diftler, Myron A. (Inventor)

    2001-01-01

    A compact robotic hand includes a palm housing, a wrist section, and a forearm section. The palm housing supports a plurality of fingers and one or more movable palm members that cooperate with the fingers to grasp and/or release an object. Each flexible finger comprises a plurality of hingedly connected segments, including a proximal segment pivotally connected to the palm housing. The proximal finger segment includes at least one groove defining first and second cam surfaces for engagement with a cable. A plurality of lead screw assemblies each carried by the palm housing are supplied with power from a flexible shaft rotated by an actuator and output linear motion to a cable move a finger. The cable is secured within a respective groove and enables each finger to move between an opened and closed position. A decoupling assembly pivotally connected to a proximal finger segment enables a cable connected thereto to control movement of an intermediate and distal finger segment independent of movement of the proximal finger segment. The dexterous robotic hand closely resembles the function of a human hand yet is light weight and capable of grasping both heavy and light objects with a high degree of precision.

  14. Magnetically mediated thermoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Feng, Xiaohua; Gao, Fei; Zheng, Yuanjin

    2014-03-01

    In this paper, alternating magnetic field is explored for inducing thermoacoustic effect on dielectric objects. Termed as magnetically mediated thermo-acoustic (MMTA) effect that provides a contrast in conductivity, this approach employs magnetic resonance for delivering energy to a desired location by applying a large transient current at radio frequency below 50MHz to a compact magnetically resonant coil. The alternating magnetic field induces large electric field inside conductive objects, which then undergoes joule heating and emanates acoustic signal thermo-elastically. The magnetic mediation approach with low radio frequency can potentially provide deeper penetration than microwave radiation due to the non-magnetic nature of human body and therefore extend thermoacoustic imaging to deep laid organs. Both incoherent time domain method that applies a pulsed radio frequency current and coherent frequency domain approach that employs a linear chirp signal to modulate the envelop of the current are discussed. Owing to the coherent processing nature, the latter approach is capable of achieving much better signal to noise ratio and therefore potential for portable imaging system. Phantom experiments are carried out to demonstrate the signal generation together with some preliminary imaging results. Ex-vivo tissue studies are also investigated.

  15. Compaction behavior of isomalt after roll compaction.

    PubMed

    Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

    2012-01-01

    The suitability of the new isomalt grade galenIQ™ 801 for dry granulation and following tableting is evaluated in this study. Isomalt alone, as well as a blend of equal parts with dibasic calcium phosphate, is roll compacted and tableted. Particle size distribution and flowability of the granules and friability and disintegration time of the tablets are determined. Tensile strength of tablets is related to the specific compaction force during roll compaction and the tableting force. In all cases, the tensile strength increases with raising tableting forces. The specific compaction force has a different influence. For isomalt alone the tensile strength is highest for tablets made from granules prepared at 2 kN/cm and 6 kN/cm and decreases at higher values, i.e., >10 kN/cm. Tensile strength of the blend tablets is almost one third lower compared to the strongest tablets of pure isomalt. Friability of pure isomalt tablets is above the limit. Disintegration time is longest when the tensile strength is at its maximum and decreases with higher porosity and lower tensile strengths. Isomalt proves to be suitable for tableting after roll compaction. Even though the capacity as a binder might not be as high as of other excipients, it is a further alternative for the formulation scientist. PMID:24300366

  16. Compaction Behavior of Isomalt after Roll Compaction

    PubMed Central

    Quodbach, Julian; Mosig, Johanna; Kleinebudde, Peter

    2012-01-01

    The suitability of the new isomalt grade galenIQ™ 801 for dry granulation and following tableting is evaluated in this study. Isomalt alone, as well as a blend of equal parts with dibasic calcium phosphate, is roll compacted and tableted. Particle size distribution and flowability of the granules and friability and disintegration time of the tablets are determined. Tensile strength of tablets is related to the specific compaction force during roll compaction and the tableting force. In all cases, the tensile strength increases with raising tableting forces. The specific compaction force has a different influence. For isomalt alone the tensile strength is highest for tablets made from granules prepared at 2 kN/cm and 6 kN/cm and decreases at higher values, i.e., >10 kN/cm. Tensile strength of the blend tablets is almost one third lower compared to the strongest tablets of pure isomalt. Friability of pure isomalt tablets is above the limit. Disintegration time is longest when the tensile strength is at its maximum and decreases with higher porosity and lower tensile strengths. Isomalt proves to be suitable for tableting after roll compaction. Even though the capacity as a binder might not be as high as of other excipients, it is a further alternative for the formulation scientist. PMID:24300366

  17. Optimal control of objects on the micro- and nano-scale by electrokinetic and electromagnetic manipulation: For bio-sample preparation, quantum information devices and magnetic drug delivery

    NASA Astrophysics Data System (ADS)

    Probst, Roland

    In this thesis I show achievements for precision feedback control of objects inside micro-fluidic systems and for magnetically guided ferrofluids. Essentially, this is about doing flow control, but flow control on the microscale, and further even to nanoscale accuracy, to precisely and robustly manipulate micro and nano-objects (i.e. cells and quantum dots). Target applications include methods to miniaturize the operations of a biological laboratory (lab-on-a-chip), i.e. presenting pathogens to on-chip sensing cells or extracting cells from messy bio-samples such as saliva, urine, or blood; as well as non-biological applications such as deterministically placing quantum dots on photonic crystals to make multi-dot quantum information systems. The particles are steered by creating an electrokinetic fluid flow that carries all the particles from where they are to where they should be at each time step. The control loop comprises sensing, computation, and actuation to steer particles along trajectories. Particle locations are identified in real-time by an optical system and transferred to a control algorithm that then determines the electrode voltages necessary to create a flow field to carry all the particles to their next desired locations. The process repeats at the next time instant. I address following aspects of this technology. First I explain control and vision algorithms for steering single and multiple particles, and show extensions of these algorithms for steering in three dimensional (3D) spaces. Then I show algorithms for calculating power minimum paths for steering multiple particles in actuation constrained environments. With this microfluidic system I steer biological cells and nano particles (quantum dots) to nano meter precision. In the last part of the thesis I develop and experimentally demonstrate two dimensional (2D) manipulation of a single droplet of ferrofluid by feedback control of 4 external electromagnets, with a view towards enabling

  18. Magnet innovations for linacs

    SciTech Connect

    Halbach, K.

    1986-06-01

    It is possible to produce large magnetic fields at the aperture of permanent magnet quadrupoles, even when the magnetic aperture is very small. That, combined with their compactness, makes permanent magnet quadrupoles very powerful components of small aperture linacs. Results will be presented about past and present work on both fixed and variable strength permanent magnets suitable for use in and around linacs.

  19. ACOUSTIC COMPACTION LAYER DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The depth and strength of compacted layers in fields have been determined traditionally using the ASAE standardized cone penetrometer method. However, an on-the-go method would be much faster and much less labor intensive. The soil measurement system described here attempts to locate the compacted...

  20. Dynamical compactness and sensitivity

    NASA Astrophysics Data System (ADS)

    Huang, Wen; Khilko, Danylo; Kolyada, Sergiĭ; Zhang, Guohua

    2016-05-01

    To link the Auslander point dynamics property with topological transitivity, in this paper we introduce dynamically compact systems as a new concept of a chaotic dynamical system (X , T) given by a compact metric space X and a continuous surjective self-map T : X → X. Observe that each weakly mixing system is transitive compact, and we show that any transitive compact M-system is weakly mixing. Then we discuss the relationships between it and other several stronger forms of sensitivity. We prove that any transitive compact system is Li-Yorke sensitive and furthermore multi-sensitive if it is not proximal, and that any multi-sensitive system has positive topological sequence entropy. Moreover, we show that multi-sensitivity is equivalent to both thick sensitivity and thickly syndetic sensitivity for M-systems. We also give a quantitative analysis for multi-sensitivity of a dynamical system.

  1. Compaction properties of isomalt.

    PubMed

    Bolhuis, Gerad K; Engelhart, Jeffrey J P; Eissens, Anko C

    2009-08-01

    Although other polyols have been described extensively as filler-binders in direct compaction of tablets, the polyol isomalt is rather unknown as pharmaceutical excipient, in spite of its description in all the main pharmacopoeias. In this paper the compaction properties of different types of ispomalt were studied. The types used were the standard product sieved isomalt, milled isomalt and two types of agglomerated isomalt with a different ratio between 6-O-alpha-d-glucopyranosyl-d-sorbitol (GPS) and 1-O-alpha-d-glucopyranosyl-d-mannitol dihydrate (GPM). Powder flow properties, specific surface area and densities of the different types were investigated. Compactibility was investigated by compression of the tablets on a compaction simulator, simulating the compression on high-speed tabletting machines. Lubricant sensitivity was measured by compressing unlubricated tablets and tablets lubricated with 1% magnesium stearate on an instrumented hydraulic press. Sieved isomalt had excellent flow properties but the compactibility was found to be poor whereas the lubricant sensitivity was high. Milling resulted in both a strong increase in compactibility as an effect of the higher surface area for bonding and a decrease in lubricant sensitivity as an effect of the higher surface area to be coated with magnesium stearate. However, the flow properties of milled isomalt were too bad for use as filler-binder in direct compaction. Just as could be expected, agglomeration of milled isomalt by fluid bed agglomeration improved flowability. The good compaction properties and the low lubricant sensitivity were maintained. This effect is caused by an early fragmentation of the agglomerated material during the compaction process, producing clean, lubricant-free particles and a high surface for bonding. The different GPS/GPM ratios of the agglomerated isomalt types studied had no significant effect on the compaction properties. PMID:19327398

  2. Stabilization of compactible waste

    SciTech Connect

    Franz, E.M.; Heiser, J.H. III; Colombo, P.

    1990-09-01

    This report summarizes the results of series of experiments performed to determine the feasibility of stabilizing compacted or compactible waste with polymers. The need for this work arose from problems encountered at disposal sites attributed to the instability of this waste in disposal. These studies are part of an experimental program conducted at Brookhaven National Laboratory (BNL) investigating methods for the improved solidification/stabilization of DOE low-level wastes. The approach taken in this study was to perform a series of survey type experiments using various polymerization systems to find the most economical and practical method for further in-depth studies. Compactible dry bulk waste was stabilized with two different monomer systems: styrene-trimethylolpropane trimethacrylate (TMPTMA) and polyester-styrene, in laboratory-scale experiments. Stabilization was accomplished by wetting or soaking compactible waste (before or after compaction) with monomers, which were subsequently polymerized. Three stabilization methods are described. One involves the in-situ treatment of compacted waste with monomers in which a vacuum technique is used to introduce the binder into the waste. The second method involves the alternate placement and compaction of waste and binder into a disposal container. In the third method, the waste is treated before compaction by wetting the waste with the binder using a spraying technique. A series of samples stabilized at various binder-to-waste ratios were evaluated through water immersion and compression testing. Full-scale studies were conducted by stabilizing two 55-gallon drums of real compacted waste. The results of this preliminary study indicate that the integrity of compacted waste forms can be readily improved to ensure their long-term durability in disposal environments. 9 refs., 10 figs., 2 tabs.

  3. Particle acceleration from an inner accretion disc into compact corona and further out: case of an organised magnetic field near a supermassive black hole

    NASA Astrophysics Data System (ADS)

    Karas, Vladimir; Kopacek, Ondrej; Kunneriath, Devaky; Kovar, Jiri; Slany, Petr

    2016-04-01

    Upcoming observational techniques in X-rays and millimeter spectral bands will allow to probe the inner corona of accretion discs near supermassive black holes. Size of this region only a few gravitational radii has been inferred from various circumstantial evidence. To populate ithe region with particles, pair-creation in ergosphere and transport of particles via accretion have been invoked.Electromagnetic fields are a likely agent of acceleration in strong gravity of a rotating black hole. We put forward a scenario with an organised component of the magnetic field near a supermassive black hole. An emergent flow of particles may be induced in a preferentially bi-polar direction. Our mechanism does not seem to be capable of producing ultra-high energy cosmic rays but it does expel particles along unbound trajectories.The mentioned concept is relevant also from a purely theoretical viewpoint of dynamical properties of particle motion in General Relativity, namely, the onset of chaos near a black hole. We conclude that the role of black-hole spin in setting the chaos is more complicated than initially thought (based on http://arxiv.org/abs/1408.2452).

  4. Momentum compaction and phase slip factor

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-10-01

    Section 2.3.11 of the Handbook of Accelerator Physics and Engineering on Landau damping is updated. The slip factor and its higher orders are given in terms of the various orders of the momentum compaction. With the aid of a simplified FODO lattice, formulas are given for the alteration of the lower orders of the momentum compaction by various higher multipole magnets. The transition to isochronicity is next demonstrated. Formulas are given for the extraction of the first three orders of the slip factor from the measurement of the synchrotron tune while changing the rf frequency. Finally bunch-length compression experiments in semi-isochronous rings are reported.

  5. A newly discovered compact planetary nebula

    NASA Astrophysics Data System (ADS)

    Cappellaro, E.; Turatto, M.; Sabbadin, F.

    1989-07-01

    An H-alpha emission object is identified in a 103a-E + RG1 objective prism plate taken with the 92/67-cm Schmidt telescope of the Astronomical Observatory of Padua at Asiago (Italy). The object turns out to be a compact planetary nebula located at alpha(1950.0) = 18 h 4.3 min and delta(1950.0) = -8 deg 56.4 arcmin (classification code: 19 + 5 deg 1).

  6. A compact THz imaging system

    NASA Astrophysics Data System (ADS)

    Sešek, Aleksander; Å vigelj, Andrej; Trontelj, Janez

    2015-03-01

    The objective of this paper is the development of a compact low cost imaging THz system, usable for observation of the objects near to the system and also for stand-off detection. The performance of the system remains at the high standard of more expensive and bulkiest system on the market. It is easy to operate as it is not dependent on any fine mechanical adjustments. As it is compact and it consumes low power, also a portable system was developed for stand-off detection of concealed objects under textile or inside packages. These requirements rule out all optical systems like Time Domain Spectroscopy systems which need fine optical component positioning and requires a large amount of time to perform a scan and the image capture pixel-by-pixel. They are also almost not suitable for stand-off detection due to low output power. In the paper the antenna - bolometer sensor microstructure is presented and the THz system described. Analysis and design guidelines for the bolometer itself are discussed. The measurement results for both near and stand-off THz imaging are also presented.

  7. New charged anisotropic compact models

    NASA Astrophysics Data System (ADS)

    Kileba Matondo, D.; Maharaj, S. D.

    2016-07-01

    We find new exact solutions to the Einstein-Maxwell field equations which are relevant in the description of highly compact stellar objects. The relativistic star is charged and anisotropic with a quark equation of state. Exact solutions of the field equations are found in terms of elementary functions. It is interesting to note that we regain earlier quark models with uncharged and charged matter distributions. A physical analysis indicates that the matter distributions are well behaved and regular throughout the stellar structure. A range of stellar masses are generated for particular parameter values in the electric field. In particular the observed mass for a binary pulsar is regained.

  8. Compact microchannel system

    DOEpatents

    Griffiths, Stewart

    2003-09-30

    The present invention provides compact geometries for the layout of microchannel columns through the use of turns and straight channel segments. These compact geometries permit the use of long separation or reaction columns on a small microchannel substrate or, equivalently, permit columns of a fixed length to occupy a smaller substrate area. The new geometries are based in part on mathematical analyses that provide the minimum turn radius for which column performance in not degraded. In particular, we find that straight channel segments of sufficient length reduce the required minimum turn radius, enabling compact channel layout when turns and straight segments are combined. The compact geometries are obtained by using turns and straight segments in overlapped or nested arrangements to form pleated or coiled columns.

  9. Compact baby Skyrmions

    SciTech Connect

    Adam, C.; Klimas, P.; Sanchez-Guillen, J.; Wereszczynski, A.

    2009-11-15

    For the baby Skyrme model with a specific potential, compacton solutions, i.e., configurations with a compact support and parabolic approach to the vacuum, are derived. Specifically, in the nontopological sector, we find spinning Q-balls and Q-shells, as well as peakons. Moreover, we obtain compact baby skyrmions with nontrivial topological charge. All these solutions may form stable multisoliton configurations provided they are sufficiently separated.

  10. Ultrathin zoom telescopic objective.

    PubMed

    Li, Lei; Wang, Di; Liu, Chao; Wang, Qiong-Hua

    2016-08-01

    We report an ultrathin zoom telescopic objective that can achieve continuous zoom change and has reduced compact volume. The objective consists of an annular folded lens and three electrowetting liquid lenses. The annular folded lens undertakes the main part of the focal power of the lens system. Due to a multiple-fold design, the optical path is folded in a lens with the thickness of ~1.98mm. The electrowetting liquid lenses constitute a zoom part. Based on the proposed objective, an ultrathin zoom telescopic camera is demonstrated. We analyze the properties of the proposed objective. The aperture of the proposed objective is ~15mm. The total length of the system is ~18mm with a tunable focal length ~48mm to ~65mm. Compared with the conventional zoom telescopic objective, the total length has been largely reduced. PMID:27505830

  11. Compact Grism Spectrometer

    NASA Astrophysics Data System (ADS)

    Teare, S. W.

    2003-05-01

    Many observatories and instrument builders are retrofitting visible and near-infrared spectrometers into their existing imaging cameras. Camera designs that reimage the focal plane and have the optical filters located in a pseudo collimated beam are ideal candidates for the addition of a spectrometer. One device commonly used as the dispersing element for such spectrometers is a grism. The traditional grism is constructed from a prism that has had a diffraction grating applied on one surface. The objective of such a design is to use the prism wedge angle to select the desired "in-line" or "zero-deviation" wavelength that passes through on axis. The grating on the surface of the prism provides much of the dispersion for the spectrometer. A grism can also be used in a "constant-dispersion" design which provides an almost linear spatial scale across the spectrum. In this paper we provide an overview of the development of a grism spectrometer for use in a near infrared camera and demonstrate that a compact grism spectrometer can be developed on a very modest budget that can be afforded at almost any facility. The grism design was prototyped using visible light and then a final device was constructed which provides partial coverage in the near infrared I, J, H and K astronomical bands using the appropriate band pass filter for order sorting. The near infrared grism presented here provides a spectral resolution of about 650 and velocity resolution of about 450 km/s. The design of this grism relied on a computer code called Xspect, developed by the author, to determine the various critical parameters of the grism. This work was supported by a small equipment grant from NASA and administered by the AAS.

  12. Operation of a 400 MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7-x high-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1 GHz

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Y.; Piao, R.; Iguchi, S.; Nakagome, H.; Takao, T.; Kominato, K.; Hamada, M.; Matsumoto, S.; Suematsu, H.; Jin, X.; Takahashi, M.; Yamazaki, T.; Maeda, H.

    2014-12-01

    High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1 GHz (23.5 T). (RE)Ba2Cu3O7-x (REBCO, RE: rare earth) conductors have an advantage over Bi2Sr2Ca2Cu3O10-x (Bi-2223) and Bi2Sr2CaCu2O8-x (Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world's first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400 MHz (9.39 T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2 GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current.

  13. Operation of a 400MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7-x high-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1GHz.

    PubMed

    Yanagisawa, Y; Piao, R; Iguchi, S; Nakagome, H; Takao, T; Kominato, K; Hamada, M; Matsumoto, S; Suematsu, H; Jin, X; Takahashi, M; Yamazaki, T; Maeda, H

    2014-10-18

    High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1GHz (23.5T). (RE)Ba2Cu3O7-x (REBCO, RE: rare earth) conductors have an advantage over Bi2Sr2Ca2Cu3O10-x (Bi-2223) and Bi2Sr2CaCu2O8-x (Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world's first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400MHz (9.39T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current. PMID:25462945

  14. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  15. Determining the Location, Number Density and Temporal Evolution of Streams of Hazardous Near-Earth Objects Using the Magnetic Signatures Produced in Destructive Collisions

    NASA Astrophysics Data System (ADS)

    Lai, H.; Russell, C. T.; Wei, H.; Delzanno, G. L.; Connors, M. G.

    2014-12-01

    Near-Earth objects (NEOs) of tens of meters in diameter are difficult to detect by optical methods from the Earth but they result in the most damage per year. Many of these bodies are produced in non-destructive collisions with larger well-characterized NEOs. After generation, the debris spreads forward and backward in a cocoon around the orbit of the parent body. Thereafter, scattering will occur due to gravitational perturbations when the debris stream passes near a planet even when the parent body has no such close approaches. Therefore "safe" NEOs which have no close encounters to the Earth for thousands of years may be accompanied by potentially hazardous co-orbiting debris. We have developed a technique to identify co-orbiting debris by detecting the magnetic signature produced when some of the debris suffers destructive collisions with meteoroids, which are numerous and can be as small as tens of centimeters in diameter. Clouds of nanoscale dust/gas particles released in such collisions can interact coherently with the solar wind electromagnetically. The resultant magnetic perturbations are readily identified when they pass spacecraft equipped with magnetometers. We can use such observations to obtain the spatial and size distribution as well as temporal variation of the debris streams. A test of this technique has been performed and debris streams both leading and trailing asteroid 138175 have been identified. There is a finite spread across the original orbit and most of the co-orbitals were tens of meters in diameter before the disruptive collisions. We estimate that there were tens of thousands of such co-orbiting objects, comprising only 1% of the original mass of the parent asteroid but greatly increasing the impact hazard. A loss of the co-orbitals since 1970s has been inferred from observations with a decay time consistent with that calculated from the existing collisional model [Grün et al., 1985]. Therefore disruptive collisions are the main loss

  16. Saloplastics: processing compact polyelectrolyte complexes.

    PubMed

    Schaaf, Pierre; Schlenoff, Joseph B

    2015-04-17

    Polyelectrolyte complexes (PECs) are prepared by mixing solutions of oppositely charged polyelectrolytes. These diffuse, amorphous precipitates may be compacted into dense materials, CoPECs, by ultracentrifugation (ucPECs) or extrusion (exPECs). The presence of salt water is essential in plasticizing PECs to allow them to be reformed and fused. When hydrated, CoPECs are versatile, rugged, biocompatible, elastic materials with applications including bioinspired materials, supports for enzymes and (nano)composites. In this review, various methods for making CoPECs are described, as well as fundamental responses of CoPEC mechanical properties to salt concentration. Possible applications as synthetic cartilage, enzymatically active biocomposites, self-healing materials, and magnetic nanocomposites are presented. PMID:25771881

  17. Experimental studies of compact toroids

    SciTech Connect

    Not Available

    1991-01-01

    The Berkeley Compact Toroid Experiment (BCTX) device is a plasma device with a Marshall-gun generated, low aspect ratio toroidal plasma. The device is capable of producing spheromak-type discharges and may, with some modification, produce low-aspect ratio tokamak configurations. A unique aspect of this experimenal devie is its large lower hybrid (LH) heating system, which consists of two 450MHz klystron tubes generating 20 megawatts each into a brambilla-type launching structure. Successful operation with one klystron at virtually full power (18 MW) has been accomplished with 110 {mu}s pulse length. A second klystron is currently installed in its socket and magnet but has not been added to the RF drive system. This report describes current activities and accomplishments and describes the anticipated results of next year's activity.

  18. Numerical modeling of higher order magnetic moments in UXO discrimination

    USGS Publications Warehouse

    Sanchez, V.; Yaoguo, L.; Nabighian, M.N.; Wright, D.L.

    2008-01-01

    The surface magnetic anomaly observed in unexploded ordnance (UXO) clearance is mainly dipolar, and consequently, the dipole is the only magnetic moment regularly recovered in UXO discrimination. The dipole moment contains information about the intensity of magnetization but lacks information about the shape of the target. In contrast, higher order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and to show its potential utility in UXO clearance, we present a numerical modeling study of UXO and related metallic objects. The tool for the modeling is a nonlinear integral equation describing magnetization within isolated compact objects of high susceptibility. A solution for magnetization distribution then allows us to compute the magnetic multipole moments of the object, analyze their relationships, and provide a depiction of the anomaly produced by different moments within the object. Our modeling results show the presence of significant higher order moments for more asymmetric objects, and the fields of these higher order moments are well above the noise level of magnetic gradient data. The contribution from higher order moments may provide a practical tool for improved UXO discrimination. ?? 2008 IEEE.

  19. Soil compaction across the old rotation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evaluating soil compaction levels across the Old Rotation, the world’s oldest continuous cotton (Gossypium hirsutum L.) experiment, has not been conducted since the experiment transitioned to conservation tillage and high residue cover crops with and without irrigation. Our objective was to charact...

  20. The missing compact star of SN1987A: a solid quark star?

    NASA Astrophysics Data System (ADS)

    Liu, X. W.; Liang, J. D.; Xu, R. X.; Han, J. L.; Qiao, G. J.

    2012-08-01

    To investigate the missing compact star of Supernova 1987A (SN1987A), we analysed the cooling and heating processes of a possible compact star based on the upper limit of observational X-ray luminosity. From the cooling process, we found that a solid quark-cluster star (SQS), having a stiffer equation of state than that of a conventional liquid quark star, has a heat capacity much smaller than a neutron star. The SQS can cool down quickly, naturally explaining the non-detection of a point source in X-ray wavelengths. On the other hand, we considered the heating processes due to magnetospheric activity and possible accretion, and obtained some constraints on the parameters of a possible pulsar. Therefore, we concluded that an SQS can explain the observational limit in a confident parameter space. With a short period and a strong magnetic field (or with a long period and weak field), a pulsar would have a luminosity higher than the observational limit if the optical depth is not large enough to hide the compact star. As possible central compact objects, the parameters constrained for a pulsar can be tested for SN1987A with advanced facilities in the future.

  1. Mapping the QCD Phase Transition with Accreting Compact Stars

    SciTech Connect

    Blaschke, D.; Poghosyan, G.; Grigorian, H.

    2008-10-29

    We discuss an idea for how accreting millisecond pulsars could contribute to the understanding of the QCD phase transition in the high-density nuclear matter equation of state (EoS). It is based on two ingredients, the first one being a ''phase diagram'' of rapidly rotating compact star configurations in the plane of spin frequency and mass, determined with state-of-the-art hybrid equations of state, allowing for a transition to color superconducting quark matter. The second is the study of spin-up and accretion evolution in this phase diagram. We show that the quark matter phase transition leads to a characteristic line in the {omega}-M plane, the phase border between neutron stars and hybrid stars with a quark matter core. Along this line a drop in the pulsar's moment of inertia entails a waiting point phenomenon in the accreting millisecond pulsar (AMXP) evolution: most of these objects should therefore be found along the phase border in the {omega}-M plane, which may be viewed as the AMXP analog of the main sequence in the Hertzsprung-Russell diagram for normal stars. In order to prove the existence of a high-density phase transition in the cores of compact stars we need population statistics for AMXPs with sufficiently accurate determination of their masses, spin frequencies and magnetic fields.

  2. Proposal to produce large compact toroids

    SciTech Connect

    Phillips, J.A.

    1981-03-01

    Relatively large, hot compact toroids might be produced in the annular space between two concentric one-turn coils. With currents in the two coils flowing in the same direction, the magnetic fields on each side of the plasma are in opposite directions. As the fields are raised, the plasma ring is heated and compressed radially towards the center of the annular space. By the addition of two sets of auxiliary coils, the plasma ring can be ejected out one end of the two-coil system into a long axial magnetic field.

  3. Ceramic compaction models: Useful design tools or simple trend indicators?

    SciTech Connect

    Mahoney, F.M.; Readey, M.J.

    1995-08-01

    It is well-known that dry pressing of ceramic powders leads to density gradients in a ceramic compact resulting in non-uniform shrinkage during densification. This necessitates diamond grinding to final dimensions which, in addition to being an extra processing step, greatly increases the manufacturing cost of ceramic components. To develop methods to control and thus mitigate density variations in compacted powders, it has been an objective of researchers to better understand the mechanics of the compaction process and the underlying material and tooling effects on the formation of density gradients. This paper presents a review of models existing in the literature related to the compaction behavior of ceramic powders. In particular, this paper focuses on several well-known compaction models that predict pressure and density variations in powder compacts.

  4. Limestone compaction: an enigma

    USGS Publications Warehouse

    Shinn, Eugene A.; Halley, Robert B.; Hudson, J. Harold; Lidz, Barbara H.

    1977-01-01

    Compression of an undisturbed carbonate sediment core under a pressure of 556 kg/cm2 produced a “rock” with sedimentary structures similar to typical ancient fine-grained limestones. Surprisingly, shells, foraminifera, and other fossils were not noticeably crushed, which indicates that absence of crushed fossils in ancient limestones can no longer be considered evidence that limestones do not compact.

  5. Compact optical transconductance varistor

    SciTech Connect

    Sampayan, Stephen

    2015-09-22

    A compact radiation-modulated transconductance varistor device having both a radiation source and a photoconductive wide bandgap semiconductor material (PWBSM) integrally formed on a substrate so that a single interface is formed between the radiation source and PWBSM for transmitting PWBSM activation radiation directly from the radiation source to the PWBSM.

  6. COMPACT SCHOOL AND $$ SAVINGS.

    ERIC Educational Resources Information Center

    BAIR, W.G.

    A REVIEW OF THE CRITERIA FOR CONSIDERING THE USE OF A TOTAL ENERGY SYSTEM WITHIN A SCHOOL BUILDING STATES THE WINDOWLESS, COMPACT SCHOOL OFFERS MORE EFFICIENT SPACE UTILIZATION WITH LESS AREA REQUIRED FOR GIVEN STUDENT POPULATION AND LOWER OPERATION COSTS. THE AUTHOR RECOMMENDS THAT THESE BUILDINGS BE WINDOWLESS TO REDUCE HEAT COSTS, HOWEVER, AT…

  7. General Relativity&Compact Stars

    SciTech Connect

    Glendenning, Norman K.

    2005-08-16

    Compact stars--broadly grouped as neutron stars and white dwarfs--are the ashes of luminous stars. One or the other is the fate that awaits the cores of most stars after a lifetime of tens to thousands of millions of years. Whichever of these objects is formed at the end of the life of a particular luminous star, the compact object will live in many respects unchanged from the state in which it was formed. Neutron stars themselves can take several forms--hyperon, hybrid, or strange quark star. Likewise white dwarfs take different forms though only in the dominant nuclear species. A black hole is probably the fate of the most massive stars, an inaccessible region of spacetime into which the entire star, ashes and all, falls at the end of the luminous phase. Neutron stars are the smallest, densest stars known. Like all stars, neutron stars rotate--some as many as a few hundred times a second. A star rotating at such a rate will experience an enormous centrifugal force that must be balanced by gravity or else it will be ripped apart. The balance of the two forces informs us of the lower limit on the stellar density. Neutron stars are 10{sup 14} times denser than Earth. Some neutron stars are in binary orbit with a companion. Application of orbital mechanics allows an assessment of masses in some cases. The mass of a neutron star is typically 1.5 solar masses. They can therefore infer their radii: about ten kilometers. Into such a small object, the entire mass of our sun and more, is compressed.

  8. Compact stellarators with modular coils

    PubMed Central

    Garabedian, P. R.

    2000-01-01

    Compact stellarator designs with modular coils and only two or three field periods are now available; these designs have both good stability and quasiaxial symmetry providing adequate transport for a magnetic fusion reactor. If the bootstrap current assumes theoretically predicted values a three field period configuration is optimal, but if that net current turns out to be lower, a device with two periods and just 12 modular coils might be better. There are also attractive designs with quasihelical symmetry and four or five periods whose properties depend less on the bootstrap current. Good performance requires that there be a satisfactory magnetic well in the vacuum field, which is a property lacking in a stellarator-tokamak hybrid that has been proposed for a proof of principle experiment. In this paper, we present an analysis of stability for these configurations that is based on a mountain pass theorem asserting that, if two solutions of the problem of magnetohydrodynamic equilibrium can be found, then there has to be an unstable solution. We compare results of our theory of equilibrium, stability, and transport with recently announced measurements from the large LHD experiment in Japan. PMID:10899993

  9. The Planck Compact Source Catalogues

    NASA Astrophysics Data System (ADS)

    Lopez-Caniego, Marcos

    2015-12-01

    The Second Planck Catalogue of Compact Sources is a catalogue of sources observed over the entire sky at nine different frequencies between 30 and 857 GHz. It consists of Galactic and extragalactic objects detected in the Planck single-frequency full mission total intensity maps. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two sub·catalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The PCCS2 covers most of the sky and can be used to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The PCCS2E contains sources located in certain regions where the complex background makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels.

  10. Cold compaction of water ice

    USGS Publications Warehouse

    Durham, W.B.; McKinnon, W.B.; Stern, L.A.

    2005-01-01

    Hydrostatic compaction of granulated water ice was measured in laboratory experiments at temperatures 77 K to 120 K. We performed step-wise hydrostatic pressurization tests on 5 samples to maximum pressures P of 150 MPa, using relatively tight (0.18-0.25 mm) and broad (0.25-2.0 mm) starting grain-size distributions. Compaction change of volume is highly nonlinear in P, typical for brittle, granular materials. No time-dependent creep occurred on the lab time scale. Significant residual porosity (???0.10) remains even at highest P. Examination by scanning electron microscopy (SEM) reveals a random configuration of fractures and broad distribution of grain sizes, again consistent with brittle behavior. Residual porosity appears as smaller, well-supported micropores between ice fragments. Over the interior pressures found in smaller midsize icy satellites and Kuiper Belt objects (KBOs), substantial porosity can be sustained over solar system history in the absence of significant heating and resultant sintering. Copyright 2005 by the American Geophysical Union.

  11. Comparison of Obturation Quality in Modified Continuous Wave Compaction, Continuous Wave Compaction, Lateral Compaction and Warm Vertical Compaction Techniques

    PubMed Central

    Aminsobhani, Mohsen; Ghorbanzadeh, Abdollah; Sharifian, Mohammad Reza; Namjou, Sara; Kharazifard, Mohamad Javad

    2015-01-01

    Objectives: The aim of this study was to introduce modified continuous wave compaction (MCWC) technique and compare its obturation quality with that of lateral compaction (LC), warm vertical compaction (WVC) and continuous wave compaction techniques (CWC). The obturation time was also compared among the four techniques. Materials and Methods: Sixty-four single-rooted teeth with 0–5° root canal curve and 64 artificially created root canals with 15° curves in acrylic blocks were evaluated. The teeth and acrylic specimens were each divided into four subgroups of 16 for testing the obturation quality of four techniques namely LC, WVC, CWC and MCWC. Canals were prepared using the Mtwo rotary system and filled with respect to their group allocation. Obturation time was recorded. On digital radiographs, the ratio of area of voids to the total area of filled canals was calculated using the Image J software. Adaptation of the filling materials to the canal walls was assessed at three cross-sections under a stereomicroscope (X30). Data were statistically analyzed using ANOVA, Tukey’s post hoc HSD test, the Kruskal Wallis test and t-test. Results: No significant difference existed in adaptation of filling materials to canal walls among the four subgroups in teeth samples (P ≥ 0.139); but, in artificially created canals in acrylic blocks, the frequency of areas not adapted to the canal walls was significantly higher in LC technique compared to MCWC (P ≤ 0.02). The void areas were significantly more in the LC technique than in other techniques in teeth (P < 0.001). The longest obturation time belonged to WVC technique followed by LC, CW and MCWC techniques (P<0.05). The difference between the artificially created canals in blocks and teeth regarding the obturation time was not significant (P = 0.41). Conclusion: Within the limitations of this in vitro study, MCWC technique resulted in better adaptation of gutta-percha to canal walls than LC at all cross-sections with

  12. Iron-carbon compacts and process for making them

    DOEpatents

    Sheinberg, Haskell

    2000-01-01

    The present invention includes iron-carbon compacts and a process for making them. The process includes preparing a slurry comprising iron powder, furfuryl alcohol, and a polymerization catalyst for initiating the polymerization of the furfuryl alcohol into a resin, and heating the slurry to convert the alcohol into the resin. The resulting mixture is pressed into a green body and heated to form the iron-carbon compact. The compact can be used as, or machined into, a magnetic flux concentrator for an induction heating apparatus.

  13. Heteropolar Magnetic Suspension

    NASA Technical Reports Server (NTRS)

    Misovec, Kathleen; Johnson, Bruce; Downer, James; Eisenhaure, David; Hockney, Richard

    1990-01-01

    Compact permanent-magnet/electromagnet actuator has six degrees of freedom. Heteropolar magnetic actuator conceived for use as actively controlled vibration-isolating suspension device. Exerts forces along, and torques about, all three principal coordinate axes to resist all three components of translational vibration and all three components of rotational vibration. Inner cylinder suspended magnetically within outer cylinder. Electro-magnet coils interact with fields of permanent magnets to provide active control of suspending force and torque.

  14. Progress in Compact Toroid Experiments

    SciTech Connect

    Dolan, Thomas James

    2002-09-01

    The term "compact toroids" as used here means spherical tokamaks, spheromaks, and field reversed configurations, but not reversed field pinches. There are about 17 compact toroid experiments under construction or operating, with approximate parameters listed in Table 1.

  15. A Compact Central Object in the Supernova Remnant Kesteven 79

    NASA Astrophysics Data System (ADS)

    Seward, F. D.; Slane, P. O.; Smith, R. K.; Sun, M.

    2003-02-01

    A Chandra X-ray observation has detected an unresolved source at the center of the supernova remnant Kes 79. The best single-model fit to the source spectrum is a blackbody with an X-ray luminosity of LX(0.3-8.0keV)=7×1033 ergs s-1. There is no evidence for a surrounding pulsar wind nebula. There are no cataloged counterparts at other wavelengths, but the absorption is high. The source properties are similar to the central source in Cas A even though the Kes 79 remnant is considerably older.

  16. Evolution of Photon and Particle Spectra in Compact, Luminous Objects

    NASA Technical Reports Server (NTRS)

    Eilek, Jean A.; Caroff, Lawrence J.

    1995-01-01

    Physical conditions in the radiating plasma in the cores of radio-strong quasars and active galactic nuclei cannot be derived from observations until the effects of relativistic aberration are understood. This requires determining both the bulk flow speeds and any wave or signal speed in the parsec-scale nuclear jets. In this project we studied several aspects of such waves. We considered constraints on jet deceleration by mass pickup, and found that bolometric luminosities of the active nuclei cannot constrain core jet speeds usefully. We also simulated observations of ballistic, helical trajectories and helical waves moving directly outwards along the jet. We found that ballistic trajectories are not allowed by the data; the helical features seen are very likely to be helical waves. We believe these are waves propagating in the jet plasma. To this end, we studied waves propagating in relativistic pair plasma jets. In particular, we undertook a program whose goal was to determine the nature of waves which can propagate in relativistic pair plasmas, and how such waves propagating in streaming jet plasma would be observed by an external observer. We developed the possibility of using pulsars as test cases for our models; this takes advantage of new technology in pulsar observations, and the similarity of the physical conditions in the pulsar magnetosphere to the dense, relativistic pair plasmas which exist in radio-strong quasars.

  17. Recent Observational Progress on Accretion Disks Around Compact Objects

    NASA Astrophysics Data System (ADS)

    Miller, Jon M.

    2016-04-01

    Studies of accretion disks around black holes and neutron stars over the last ten years have made remarkable progress. Our understanding of disk evolution as a function of mass accretion rate is pushing toward a consensus on thin/thick disk transitions; an apparent switching between disk-driven outflow modes has emerged; and monitoring observations have revealed complex spectral energy distributions wherein disk reprocessing must be important. Detailed studies of disk winds, in particular, have the potential to reveal the basic physical processes that mediate disk accretion, and to connect with numerical simulations. This talk will review these developments and look ahead to the potential of Astro-H.

  18. Neutron and antineutron production in accretion onto compact objects

    NASA Technical Reports Server (NTRS)

    Dermer, Charles D.; Ramaty, Reuven

    1986-01-01

    Nuclear reactions in the hot accretion plasma surrounding a collapsed star are a source of neutrons, primarily through spallation and pion-producing reactions, and antineutrons, principally through the reaction p+p yields p+p+n+anti-n. We calculate spectra of neutrons and antineutrons produced by a variety of nonthermal energetic particle distributions in which the target particles are either at rest or in motion. If only neutral particles are free to escape the interaction site, a component of the proton and antiproton fluxes in the cosmic radiation results from the neutrons and antineutrons which leave the accretion plasma and subsequently decay in the interstellar medium. This additional antiproton component could account for the enhanced flux of antiprotons in the cosmic radiation, compared to values expected from the standard leaky-box model of cosmic-ray propagation and confinement. Moreover, the low-energy antiproton flux measured by Buffington et al. (1981) could result from target-particle motion in the accretion plasma. This model for the origin of antiprotons predicts a narrow 2.223 MeV line which could be observable.

  19. A XMM Survey for Compact Objects in Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    2004-01-01

    The goal of the project is to identify candidate neutron stars in Galactic supernova remnants (SNRs) through their X-ray emission. With XMM we observed the SNRs and typically find 10 - 50 X-ray sources. Almost all are either background galaxies or foreground stars. Therefore we must also pursue detailed optical/infrared follow-up observations to find counterparts for these X-ray sources and classify them. At the depth of the XMM observations, practically all confusing X-ray sources should have identifiable optical/IR counterparts. We have done a preliminary analysis of the XMM data and identified likely counterparts to the X-ray sources from available surveys(DSS, 2MASS). We then obtained wide-field optical/IR data from Palomar to get counterparts for the remaining sources. This analysis is underway: while often a single bright source is in the XMM error circle and can be considered a counterpart, in a number of cases we must do more detailed studies and evaluate several fainter optical/lR sources. We hope to have the final analysis of the XMM + Palomar data done this Fall. It is possible that additional, deeper optical/IR data may be necessary. We expect to publish our results by the end of this year.

  20. Materials needs for compact fusion reactors

    SciTech Connect

    Krakowski, R.A.

    1983-01-01

    The economic prospects for magnetic fusion energy can be dramatically improved if for the same total power output the fusion neutron first-wall (FW) loading and the system power density can be increased by factors of 3 to 5 and 10 to 30, respectively. A number of compact fusion reactor embodiments have been proposed, all of which would operate with increased FW loadings, would use thin (0.5 to 0.6 m) blankets, and would confine quasi-steady-state plasma with resistive, water-cooled copper or aluminum coils. Increased system power density (5 to 15 MWt/m/sup 3/ versus 0.3 to 0.5 MW/m/sup 3/), considerably reduced physical size of the fusion power core (FPC), and appreciably reduced economic leverage exerted by the FPC and associated physics result. The unique materials requirements anticipated for these compact reactors are outlined against the well documented backdrop provided by similar needs for the mainline approaches. Surprisingly, no single materials need that is unique to the compact systems is identified; crucial uncertainties for the compact approaches must also be addressed by the mainline approaches, particularly for in-vacuum components (FWs, limiters, divertors, etc.).

  1. Permanent magnet array for the magnetic refrigerator

    NASA Astrophysics Data System (ADS)

    Lee, S. J.; Kenkel, J. M.; Pecharsky, V. K.; Jiles, D. C.

    2002-05-01

    Recent research into the development of magnetic refrigeration (MR) operating at room temperature has shown that it can provide a reliable, energy-efficient cooling system. To enhance the cooling power of the magnetic refrigerator, it is required to use a magnetic refrigerant material with large magnetocaloric effect (MCE) at the appropriate temperature. Most advanced magnetic refrigerant materials show largest MCE at high applied magnetic fields generated by a superconducting magnet. For application of MCE to air conditioners or household refrigerators, it is essential to develop a permanent magnet array to form a compact, strong, and energy-efficient magnetic field generator. Generating a magnetic field well above the remanence of a permanent magnet material is hard to achieve through conventional designs. A permanent magnet array based on a hollow cylindrical flux source is found to provide an appropriate geometry and magnetic field strength for MR applications.

  2. Site-Specific Compaction, Soil Physical Property, and Crop Yield Relationships for Claypan Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil compaction is a concern in crop production and environmental protection. Compaction is most often quantified in the field, albeit indirectly, using cone penetrometer measurements of soil strength. The objective of this research was to relate soil compaction to soil physical properties and crop ...

  3. RELATING SPATIAL VARIATIONS IN SOIL COMPACTION TO SOIL PHYSICAL PROPERTIES AND CROP YIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil compaction is a concern in crop production and environmental protection. Compaction is most often quantified in the field, albeit indirectly, using cone penetrometer measurements of soil strength, reported as cone index (CI). The objective of this research was to relate soil compaction, measure...

  4. Compact waveguide splitter networks.

    PubMed

    Qian, Yusheng; Song, Jiguo; Kim, Seunghyun; Hu, Weisheng; Nordin, Gregory P

    2008-03-31

    We demonstrate compact waveguide splitter networks in siliconon- insulator (SOI) rib waveguides using trench-based splitters (TBSs) and bends (TBBs). Rather than a 90 degrees geometry, we use 105 degrees TBSs to facilitate reliable fabrication of high aspect ratio trenches suitable for 50/50 splitting when filled with SU8. Three dimensional (3D) finite difference time domain (FDTD) simulation is used for splitter and bend design. Measured TBB and TBS optical efficiencies are 84% and 68%, respectively. Compact 105 degrees 1 x 4, 1 x 8, and 1 x 32 trench-based splitter networks (TBSNs) are demonstrated. The measured total optical loss of the 1 x 32 TBSN is 9.15 dB. Its size is only 700 microm x 1600 microm for an output waveguide spacing of 50 microm. PMID:18542598

  5. Compact power reactor

    DOEpatents

    Wetch, Joseph R.; Dieckamp, Herman M.; Wilson, Lewis A.

    1978-01-01

    There is disclosed a small compact nuclear reactor operating in the epithermal neutron energy range for supplying power at remote locations, as for a satellite. The core contains fuel moderator elements of Zr hydride with 7 w/o of 93% enriched uranium alloy. The core has a radial beryllium reflector and is cooled by liquid metal coolant such as NaK. The reactor is controlled and shut down by moving portions of the reflector.

  6. Compact heat exchangers

    SciTech Connect

    Kays, W.M.; London, A.L.

    1984-01-01

    This third edition is an update of the second edition published in 1964. New data and more modern theoretical solutions for flow in the simple geometries are included, although this edition does not differ radically from the second edition. It contains basic test data for eleven new surface configurations, including some of the very compact ceramic matrices. Al dimensions are given in both the English and the Systeme International (SI) system of units.

  7. Compact infrared detector

    NASA Technical Reports Server (NTRS)

    Gupta, A.; Hong, S.; Moacanin, J.

    1981-01-01

    Broadband IR detector integrated into compact package for pollution monitoring and weather prediction is small, highly responsive, and immune to high noise. Sensing material is transparent sheet metalized with reflecting coating and overcoated with black material on same side. Pulse produced by chopping of infrared source beam creates transient "thermal lens" that temporarily defocuses laser beam probe. Detector monitoring beam measures defocusing which parallels infrared intensity.

  8. Granule consolidation during compaction.

    PubMed

    Rubinstein, M H

    1976-03-01

    The deformation of small cylindrical aggregates of dibasic calcium phosphate was measured during compaction. An analogy between these aggregates and cylindrical granules was proposed. No change in the original shape of the aggregates occurred; the cylindrical shape was maintained even at high compaction pressures. Relaxation of the aggregates occurred at pressures higher than 420 MNm-2 (60.9 x 10(3) lb in.-2) when removed from the compacts, but no relaxation took place at pressures below this value. In addition, the aggregates relaxed by an increase in thickness only; there was no corresponding change in diameter. Up to a pressure of 200 MNm-2 (29.0 x 10(3) lb in.-2), an increase in aggregate diameter occurred, which was accompanied by a reduction in thickness. This change produced only a small reduction in volume, which was attributable to interparticulate slippage resulting in a closer packed arrangement. At a pressure of 200 MNm-2, the aggregate diameter no longer increased because solid bridges were formed between the particles and the die wall, preventing further spreading. From 200 to 420 MNm-2, failure of the material occurred by plastic deformation, which produced only a decrease in aggregate thickness. From 420 to 800 MNm-2 (116.0 x 10(3) lb in.-2), a structure was formed that could support the applied load without further reduction of thickness, and this structure was shown to behave elastically. PMID:1263085

  9. Adaptive Objectness for Object Tracking

    NASA Astrophysics Data System (ADS)

    Liang, Pengpeng; Pang, Yu; Liao, Chunyuan; Mei, Xue; Ling, Haibin

    2016-07-01

    Object tracking is a long standing problem in vision. While great efforts have been spent to improve tracking performance, a simple yet reliable prior knowledge is left unexploited: the target object in tracking must be an object other than non-object. The recently proposed and popularized objectness measure provides a natural way to model such prior in visual tracking. Thus motivated, in this paper we propose to adapt objectness for visual object tracking. Instead of directly applying an existing objectness measure that is generic and handles various objects and environments, we adapt it to be compatible to the specific tracking sequence and object. More specifically, we use the newly proposed BING objectness as the base, and then train an object-adaptive objectness for each tracking task. The training is implemented by using an adaptive support vector machine that integrates information from the specific tracking target into the BING measure. We emphasize that the benefit of the proposed adaptive objectness, named ADOBING, is generic. To show this, we combine ADOBING with seven top performed trackers in recent evaluations. We run the ADOBING-enhanced trackers with their base trackers on two popular benchmarks, the CVPR2013 benchmark (50 sequences) and the Princeton Tracking Benchmark (100 sequences). On both benchmarks, our methods not only consistently improve the base trackers, but also achieve the best known performances. Noting that the way we integrate objectness in visual tracking is generic and straightforward, we expect even more improvement by using tracker-specific objectness.

  10. Magnetized Neutron Stars

    NASA Astrophysics Data System (ADS)

    Liebling, Steven; Anderson, Matthew; Hirschmann, Eric; Lehner, Luis; Motl, Patrick; Neilsen, David; Palenzuela, Carlos; Tohline, Joel

    2008-04-01

    Magnetized neutron stars, whether considered individually or within compact binary systems, demonstrate a number of interesting dynamical effects. Using a distributed adaptive mesh refinement (AMR) code, we evolve such stars and study their dynamics.

  11. Conditions for jet formation in accreting neutron stars: the magnetic field decay

    NASA Astrophysics Data System (ADS)

    García, Federico; Aguilera, Deborah N.; Romero, Gustavo E.

    2011-02-01

    Accreting neutron stars can produce jets only if they are weakly magnetized (B ~ 108 G). On the other hand, neutron stars are compact objects born with strong surface magnetic fields (B ~ 1012 G). In this work we study the conditions for jet formation in a binary system formed by a neutron star and a massive donor star once the magnetic field has decayed due to accretion. We solve the induction equation for the magnetic field diffusion in a realistic neutron star crust and discuss the possibility of jet launching in systems like the recently detected Supergiant Fast X-ray Transients.

  12. Magnetic

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  13. A simple scheme for injection and extraction in compact rings

    SciTech Connect

    Xu, H. S. Huang, W. H.; Tang, C. X.; Key Laboratory of Particle and Radiation Imaging, Tsinghua University, Ministry of Education, Beijing 100084

    2014-03-15

    There has been great interest in building compact synchrotrons for various applications, for example, inverse Compton scattering X-ray sources. However, the beam injection and extraction in compact rings require careful design for the lack of space. In this paper, we propose a simple combined injection-extraction scheme exploiting the fringe field of existing dipole magnets instead of additional septum magnets. This scheme is illustrated by using the 4.8 m ring proposed for Tsinghua Thomson scattering X-ray source as an example. Particle tracking is applied to demonstrate the validity of this scheme.

  14. A simple scheme for injection and extraction in compact rings.

    PubMed

    Xu, H S; Huang, W H; Tang, C X

    2014-03-01

    There has been great interest in building compact synchrotrons for various applications, for example, inverse Compton scattering X-ray sources. However, the beam injection and extraction in compact rings require careful design for the lack of space. In this paper, we propose a simple combined injection-extraction scheme exploiting the fringe field of existing dipole magnets instead of additional septum magnets. This scheme is illustrated by using the 4.8 m ring proposed for Tsinghua Thomson scattering X-ray source as an example. Particle tracking is applied to demonstrate the validity of this scheme. PMID:24689573

  15. Love Objects.

    ERIC Educational Resources Information Center

    Cusack, Lynne

    1998-01-01

    Discusses the role of "security" or "transition" objects, such as a blanket or stuffed toy, in children's development of self-comfort and autonomy. Notes the influence of parents in the child-object relationship, and discusses children's responses to losing a security object, and the developmental point at which a child will give up such an…

  16. Computer modeling of a compact isochronous cyclotron

    NASA Astrophysics Data System (ADS)

    Smirnov, V. L.

    2015-11-01

    The computer modeling methods of a compact isochronous cyclotron are described. The main stages of analysis of accelerator facilities systems are considered. The described methods are based on theoretical fundamentals of cyclotron physics and mention highlights of creation of the physical project of a compact cyclotron. The main attention is paid to the analysis of the beam dynamics, formation of a magnetic field, stability of the movement, and a realistic assessment of intensity of the generated bunch of particles. In the article, the stages of development of the accelerator computer model, analytical ways of assessment of the accelerator parameters, and the basic technique of the numerical analysis of dynamics of the particles are described.

  17. The magnetic polarizability of thin shells

    NASA Astrophysics Data System (ADS)

    Gabbay, Jonathan E.; Scott, Waymond R.

    2014-05-01

    The ability to detect and dispose of buried mines requires effective means by which to discriminate between hazardous targets and benign clutter. In that regard, wide-band electromagnetic induction (EMI) sensors have shown significant promise in their ability to classify buried metallic objects based on their response to illumination by a time-varying magnetic field. A target's scattered response may be expressed compactly in its magnetic polarizability dyadic, a form that describes the reaction of the scatterer to an arbitrary magnetic field. More specifically, a singularity expansion of the polarizability dyadic has been shown to allow for robust target discrimination. Eddy currents in a 2D surface may be expressed using a scalar stream function, an approach which is powerful since the solenoidality of the current density is enforced trivially. Using this formulation, it is possible to arrive at a modal eigenvalue expansion for the magnetic polarizability that is in the form of the singularity expansion.

  18. Magnetic fields from heterotic cosmic strings

    SciTech Connect

    Gwyn, Rhiannon; Alexander, Stephon H.; Brandenberger, Robert H.; Dasgupta, Keshav

    2009-04-15

    Large-scale magnetic fields are observed today to be coherent on galactic scales. While there exists an explanation for their amplification and their specific configuration in spiral galaxies--the dynamo mechanism--a satisfying explanation for the original seed fields required is still lacking. Cosmic strings are compelling candidates because of their scaling properties, which would guarantee the coherence on cosmological scales of any resultant magnetic fields at the time of galaxy formation. We present a mechanism for the production of primordial seed magnetic fields from heterotic cosmic strings arising from M theory. More specifically, we make use of heterotic cosmic strings stemming from M5-branes wrapped around four of the compact internal dimensions. These objects are stable on cosmological time scales and carry charged zero modes. Therefore a scaling solution of such defects will generate seed magnetic fields which are coherent on galactic scales today.

  19. Compact stars in Kaluza -Klein World

    NASA Astrophysics Data System (ADS)

    Gábor Barnaföldi, Gergely; Lévai, Péter; Lukács, Béla

    2010-03-01

    Unification and geometrization of interactions has been extensively studied during the XX. century. In this short contribution we investigated the possible effect of an extra compactified dimension (alias hypercharge) on a flavor dependent gravitational potential, proposed by Fischbach et al.. We estimated the deviation from the 3 + 1 dimensional scheme and found that, although the deviation is moderate, for celestial compact object it may be higher by orders of magnitude than in terrestrial laboratory measurements.

  20. Photometry of compact galaxies.

    NASA Technical Reports Server (NTRS)

    Shen, B. S. P.; Usher, P. D.; Barrett, J. W.

    1972-01-01

    Photometric histories of the N galaxies 3C 390.3 and PKS 0521-36. Four other compact galaxies, Markarian 9, I Zw 92, 2 Zw 136, and III Zw 77 showed no evidence of variability. The photometric histories were obtained from an exhaustive study of those plates of the Harvard collection taken with large aperture cameras. The images of all galaxies reported were indistinguishable from stars due to the camera f-ratios and low surface brightness of the outlying nebulosities of the galaxies. Standard techniques for the study of variable stars are therefore applicable.

  1. Compact Q-balls

    NASA Astrophysics Data System (ADS)

    Bazeia, D.; Losano, L.; Marques, M. A.; Menezes, R.; da Rocha, R.

    2016-07-01

    In this work we deal with non-topological solutions of the Q-ball type in two space-time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  2. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  3. Compact laser amplifier system

    DOEpatents

    Carr, R.B.

    1974-02-26

    A compact laser amplifier system is described in which a plurality of face-pumped annular disks, aligned along a common axis, independently radially amplify a stimulating light pulse. Partially reflective or lasing means, coaxially positioned at the center of each annualar disk, radially deflects a stimulating light directed down the common axis uniformly into each disk for amplification, such that the light is amplified by the disks in a parallel manner. Circumferential reflecting means coaxially disposed around each disk directs amplified light emission, either toward a common point or in a common direction. (Official Gazette)

  4. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  5. Magnetic field homogeneity perturbations in finite Halbach dipole magnets.

    PubMed

    Turek, Krzysztof; Liszkowski, Piotr

    2014-01-01

    Halbach hollow cylinder dipole magnets of a low or relatively low aspect ratio attract considerable attention due to their applications, among others, in compact NMR and MRI systems for investigating small objects. However, a complete mathematical framework for the analysis of magnetic fields in these magnets has been developed only for their infinitely long precursors. In such a case the analysis is reduced to two-dimensions (2D). The paper details the analysis of the 3D magnetic field in the Halbach dipole cylinders of a finite length. The analysis is based on three equations in which the components of the magnetic flux density Bx, By and Bz are expanded to infinite power series of the radial coordinate r. The zeroth term in the series corresponds to a homogeneous magnetic field Bc, which is perturbed by the higher order terms due to a finite magnet length. This set of equations is supplemented with an equation for the field profile B(z) along the magnet axis, presented for the first time. It is demonstrated that the geometrical factors in the coefficients of particular powers of r, defined by intricate integrals are the coefficients of the Taylor expansion of the homogeneity profile (B(z)-Bc)/Bc. As a consequence, the components of B can be easily calculated with an arbitrary accuracy. In order to describe perturbations of the field due to segmentation, two additional equations are borrowed from the 2D theory. It is shown that the 2D approach to the perturbations generated by the segmentation can be applied to the 3D Halbach structures unless r is not too close to the inner radius of the cylinder ri. The mathematical framework presented in the paper was verified with great precision by computations of B by a highly accurate integration of the magnetostatic Coulomb law and utilized to analyze the inhomogeneity of the magnetic field in the magnet with the accuracy better than 1 ppm. PMID:24316186

  6. Compaction of Titanium Powders

    SciTech Connect

    Stephen J. Gerdemann; Paul D. Jablonski

    2010-11-01

    Accurate modeling of powder densification has been an area of active research for more than 60 years. The earliest efforts were focused on linearization of the data because computers were not readily available to assist with curve-fitting methods. In this work, eight different titanium powders (three different sizes of sponge fines <150 μm, <75 μm, and < 45 μm; two different sizes of a hydride-dehydride [HDH] <75 μm and < 45 μm; an atomized powder; a commercially pure [CP] Ti powder from International Titanium Powder [ITP]; and a Ti 6 4 alloy powder) were cold pressed in a single-acting die instrumented to collect stress and deformation data during compaction. From these data, the density of each compact was calculated and then plotted as a function of pressure. The results show that densification of all the powders, regardless of particle size, shape, or chemistry, can be modeled accurately as the sum of an initial density plus the sum of a rearrangement term and a work-hardening term. These last two terms are found to be a function of applied pressure and take the form of an exponential rise.

  7. Compact electrostatic comb actuator

    DOEpatents

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  8. Objective lens

    NASA Technical Reports Server (NTRS)

    Olczak, Eugene G. (Inventor)

    2011-01-01

    An objective lens and a method for using same. The objective lens has a first end, a second end, and a plurality of optical elements. The optical elements are positioned between the first end and the second end and are at least substantially symmetric about a plane centered between the first end and the second end.

  9. Compact, On-chip, Integrated three dimensional Lattice

    NASA Astrophysics Data System (ADS)

    Tengdin, Phoebe M.; Salim, Evan A.; Anderson, Dana Z.

    2015-05-01

    We present the design of a compact atom chip system that provides a three dimensional optical lattice combined with thru-chip imaging. Optical beams are launched from fibers mounted directly to the exterior of a high resolution (0.4NA) imaging objective. Miniature polarizers, wave plates, and mirrors located on the exterior of the objective control the polarization state and alignment of the lattice, while on-chip optics are used to provide retro-reflection. Three mutually orthogonal lattice beams traverse from the ambient side of the chip through a central window of a silicon and glass substrate, intersecting 300 microns below the vacuum side chip surface. The combined atom chip and optical system fills a volume of less than 36 cm3. Atoms may be cooled using standard techniques, and directly loaded into the optical lattice. This system is designed with the intention of reducing vibrational noise, providing high resolution in-lattice imaging, combining electric and magnetic fields to generate arbitrary potentials, and performing high repetition rate experiments. This work was supported by NASA Jet Propulsion Laboratory, and the National Science Foundation Graduate Research Fellowship.

  10. Compact Plasma Accelerator for Micropropulsion Applications

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2001-01-01

    There is a need for a low power, light-weight (compact), high specific impulse electric propulsion device to satisfy mission requirements for microsatellite (1 to 20 kg) class missions. Satisfying these requirements entails addressing the general problem of generating a sufficiently dense plasma within a relatively small volume and then accelerating it. In the work presented here, the feasibility of utilizing a magnetic cusp to generate a dense plasma over small length scales of order 1 mm is investigated. This approach could potentially mitigate scaling issues associated with conventional ion thruster plasma containment schemes. Plume and discharge characteristics were documented using a Faraday probe and a retarding potential analyzer.

  11. Smart-Phone Based Magnetic Levitation for Measuring Densities.

    PubMed

    Knowlton, Stephanie; Yu, Chu Hsiang; Jain, Nupur; Ghiran, Ionita Calin; Tasoglu, Savas

    2015-01-01

    Magnetic levitation, which uses a magnetic field to suspend objects in a fluid, is a powerful and versatile technology. We develop a compact magnetic levitation platform compatible with a smart-phone to separate micro-objects and estimate the density of the sample based on its levitation height. A 3D printed attachment is mechanically installed over the existing camera unit of a smart-phone. Micro-objects, which may be either spherical or irregular in shape, are suspended in a paramagnetic medium and loaded in a microcapillary tube which is then inserted between two permanent magnets. The micro-objects are levitated and confined in the microcapillary at an equilibrium height dependent on their volumetric mass densities (causing a buoyancy force toward the edge of the microcapillary) and magnetic susceptibilities (causing a magnetic force toward the center of the microcapillary) relative to the suspending medium. The smart-phone camera captures magnified images of the levitating micro-objects through an additional lens positioned between the sample and the camera lens cover. A custom-developed Android application then analyzes these images to determine the levitation height and estimate the density. Using this platform, we were able to separate microspheres with varying densities and calibrate their levitation heights to known densities to develop a technique for precise and accurate density estimation. We have also characterized the magnetic field, the optical imaging capabilities, and the thermal state over time of this platform. PMID:26308615

  12. Smart-Phone Based Magnetic Levitation for Measuring Densities

    PubMed Central

    Knowlton, Stephanie; Yu, Chu Hsiang; Jain, Nupur

    2015-01-01

    Magnetic levitation, which uses a magnetic field to suspend objects in a fluid, is a powerful and versatile technology. We develop a compact magnetic levitation platform compatible with a smart-phone to separate micro-objects and estimate the density of the sample based on its levitation height. A 3D printed attachment is mechanically installed over the existing camera unit of a smart-phone. Micro-objects, which may be either spherical or irregular in shape, are suspended in a paramagnetic medium and loaded in a microcapillary tube which is then inserted between two permanent magnets. The micro-objects are levitated and confined in the microcapillary at an equilibrium height dependent on their volumetric mass densities (causing a buoyancy force toward the edge of the microcapillary) and magnetic susceptibilities (causing a magnetic force toward the center of the microcapillary) relative to the suspending medium. The smart-phone camera captures magnified images of the levitating micro-objects through an additional lens positioned between the sample and the camera lens cover. A custom-developed Android application then analyzes these images to determine the levitation height and estimate the density. Using this platform, we were able to separate microspheres with varying densities and calibrate their levitation heights to known densities to develop a technique for precise and accurate density estimation. We have also characterized the magnetic field, the optical imaging capabilities, and the thermal state over time of this platform. PMID:26308615

  13. Behavior of compacted lunar simulants using new vacuum triaxial device

    NASA Technical Reports Server (NTRS)

    Desai, Chandra S.; Saadatmanesh, Hamid; Allen, Thomas

    1992-01-01

    The objectives of this study are to create a lunar simulant locally from a basaltic rock and to design and develop a vacuum triaxial test device that can permit testing of compacted lunar simulant under cyclic loading with different levels of initial vacuum. Triaxial testing is performed in the device itself without removing the compacted specimen. Preliminary constrained compression and triaxial shear tests are performed to identify effects of initial confinements and vacuums. The results are used to define deformation and strength parameters. At this time, vacuum levels up to 0.0001 are possible. The research can aid in the development of compacted materials for various construction applications.

  14. METHOD OF FORMING ELONGATED COMPACTS

    DOEpatents

    Larson, H.F.

    1959-05-01

    A powder compacting procedure and apparatus which produces elongated compacts of Be is described. The powdered metal is placed in a thin metal tube which is chemically compatible to lubricant, powder, atmosphere, and die material and will undergo a high degree of plastic deformation and have intermediate hardness. The tube is capped and placed in the die, and punches are applied to the ends. During the compacting stroke the powder seizes the tube and a thickening and shortening of the tube occurs. The tube is easily removed from the die, split, and peeled from the compact. (T.R.H.)

  15. Magnetized particle motion around non-Schwarzschild black hole immersed in an external uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Rayimbaev, J. R.

    2016-09-01

    The motion of a magnetized particle orbiting around non-Schwarzschild black hole immersed in an external uniform magnetic field is considered. The influence of deformation parameter h to effective potential of the radial motion of the magnetized particle around non-Schwarzschild black hole using Hamilton-Jacobi formalism is studied. We have obtained numerical values of area Δ ρ where magnetized particles can move which is expanding (narrowing) due to the effect of the negative (positive) deformation. Finally, we have studied the collision of two particles (magnetized-neutral, magnetized-magnetized, magnetized-charged) in non-Schwarzschild spacetime and got the center-of-mass energy (E_{c.m}) for the particles. Moreover, we have found the capture radius (r_{cap}) - the distance from the central object to the point where particles collide and fall down to the central compact object. It is shown that non-Schwarzschild black holes could also act as particle accelerators with arbitrarily high center-of-mass energy.

  16. A new model for charged anisotropic compact star

    NASA Astrophysics Data System (ADS)

    Maurya, S. K.; Jasim, M. K.; Gupta, Y. K.; Smitha, T. T.

    2016-05-01

    In this paper, we have obtained a new singularity free charged anisotropic fluid solution of Einstein's field equations. The physical parameters as radial pressure, tangential pressure, energy density, charge density, electric field intensity, velocity of sound and red-shift are well behaved everywhere inside the star. The obtained compact star models can represent the observational compact objects as PSR 1937{+}21 and PSR J1614-2230.

  17. A compact Time Projection Chamber for the Crystal Ball

    NASA Astrophysics Data System (ADS)

    Steffen, O.; Wolfes, M.; Gradl, W.

    2016-07-01

    We report on a development of a compact Time Projection Chamber with triple Gas Electron Multiplier readout to replace the current tracking detector in the Crystal Ball/TAPS Experiment at the A2 Tagged Photon Facility at MAMI in Mainz, Germany. Challenges are the limitations in size and the absence of a longitudinal magnetic flied.

  18. Compact vacuum insulation embodiments

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1992-04-28

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point' or line' contacts with the metal wall sheets. In the case of monolithic spacers that form line' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included. 26 figs.

  19. Compact vacuum insulation

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1993-01-05

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  20. Compact vacuum insulation

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1993-01-01

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  1. Compact vacuum insulation embodiments

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1992-01-01

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  2. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  3. Compact SPS - Power delivery

    NASA Astrophysics Data System (ADS)

    Pospisil, M.; Pospisilova, L.

    1982-09-01

    The power deliverable by a compact solar Space Power Station (SPS) is a function of its outer surface shape. Methods of fitting the power delivery curve of such a system to different patterns of daily power demand are considered that involve the appropriate choice of the number of satellites, their maximal power, height to width ratio and the shift of longitude with respect to the receiving station. Changes in the daily delivery curve can be made by altering the longitudes and orientations of the satellites. Certain limitations to the choice of parameters exist, such as: the height to width ratio should be near 1.2, and the sum of longitude and orientation changes will probably not be greater than 50 deg. The optimization of the peak to average power ratio is also discussed.

  4. Multipurpose Compact Spectrometric Unit

    SciTech Connect

    Bocarov, Viktor; Cermak, Pavel; Mamedov, Fadahat; Stekl, Ivan

    2009-11-09

    A new standalone compact spectrometer was developed. The device consists of analog (peamplifier, amplifier) and digital parts. The digital part is based on the 160 MIPS Digital Signal Processor. It contains 20 Msps Flash-ADC, 1 MB RAM for spectra storage, 128 KB Flash/ROM for firmware storage, Real Time Clock and several voltage regulators providing the power for user peripherals (e.g. amplifier, temperature sensors, etc.). Spectrometer is connected with a notebook via high-speed USB 2.0 bus. The spectrometer is multipurpose device, which is planned to be used for measurements of Rn activities, energy of detected particles by CdTe pixel detector or for coincidence measurements.

  5. Compact ultraviolet laser

    NASA Astrophysics Data System (ADS)

    Baird, Brian Walter

    1997-09-01

    This dissertation presents theoretical analysis and experimental investigation of a compact ultraviolet laser, comprising an unstable resonator semiconductor (URSL) laser-pumped potassium titanyl phosphate (KTP) periodically segmented waveguide (PSW) laser. A comprehensive survey of existing short wavelength visible and near ultraviolet laser technologies suitable for the development of compact ultraviolet lasers is presented. This survey establishes the suitability of a diode-pumped KTP PSW laser as an attractive approach for developing a compact ultraviolet laser. Requirements for an efficient diode-pumped KTP PSW laser are given, leading to the selection of a frequency-stabilized URSL and hydrothermal KTP PSWs as the component technologies to be developed and integrated. Since the design requirements for the URSL and KTP PSW are critically dependent on a thorough understanding of the spatial mode properties of KTP PSWs, analyses and modeling of the spatial mode properties of these devices is presented using effective index method (EIM) and beam propagation method (BPM) models. In addition, a new expression for the normalized conversion efficiency is presented which explicitly incorporates the dependence of this important parameter on the lateral variation of the refractive index and d coefficient. To assess the theoretical performance of an URSL-pumped KTP PSW, the BPM model was extended to incorporate second harmonic generation. This represents an important contribution to the development of numerical methods for modeling nonlinear waveguides, in general, and provides important information on the cooperative effects of diffraction and spatial mode beating on the SHG output from KTP PSWs. Extensive optical characterization of NUV SHG in hydrothermal KTP PSWs using an argon-ion laser-pumped Ti:Sapphire laser as the infrared laser pump source is presented. Spectral characterization, spatial mode characterization, and the temperature dependence of the QPM

  6. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  7. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  8. Compact artificial hand

    NASA Technical Reports Server (NTRS)

    Wiker, G. A.; Mann, W. A. (Inventor)

    1979-01-01

    A relatively simple, compact artificial hand, is described which includes hooks pivotally mounted on first frame to move together and apart. The first frame is rotatably mounted on a second frame to enable "turning at the wrist" movement without limitation. The second frame is pivotally mounted on a third frame to permit 'flexing at the wrist' movement. A hook-driving motor is fixed to the second frame but has a shaft that drives a speed reducer on the first frame which, in turn, drives the hooks. A second motor mounted on the second frame, turns a gear on the first frame to rotate the first frame and the hooks thereon. A third motor mounted on the third frame, turns a gear on a second frame to pivot it.

  9. Trusted Objects

    SciTech Connect

    CAMPBELL,PHILIP L.; PIERSON,LYNDON G.; WITZKE,EDWARD L.

    1999-10-27

    In the world of computers a trusted object is a collection of possibly-sensitive data and programs that can be allowed to reside and execute on a computer, even on an adversary's machine. Beyond the scope of one computer we believe that network-based agents in high-consequence and highly reliable applications will depend on this approach, and that the basis for such objects is what we call ''faithful execution.''

  10. Compact toroid injection into C-2U

    NASA Astrophysics Data System (ADS)

    Roche, Thomas; Gota, H.; Garate, E.; Asai, T.; Matsumoto, T.; Sekiguchi, J.; Putvinski, S.; Allfrey, I.; Beall, M.; Cordero, M.; Granstedt, E.; Kinley, J.; Morehouse, M.; Sheftman, D.; Valentine, T.; Waggoner, W.; the TAE Team

    2015-11-01

    Sustainment of an advanced neutral beam-driven FRC for a period in excess of 5 ms is the primary goal of the C-2U machine at Tri Alpha Energy. In addition, a criteria for long-term global sustainment of any magnetically confined fusion reactor is particle refueling. To this end, a magnetized coaxial plasma-gun has been developed. Compact toroids (CT) are to be injected perpendicular to the axial magnetic field of C-2U. To simulate this environment, an experimental test-stand has been constructed. A transverse magnetic field of B ~ 1 kG is established (comparable to the C-2U axial field) and CTs are fired across it. As a minimal requirement, the CT must have energy density greater than that of the magnetic field it is to penetrate, i.e., 1/2 ρv2 >=B2 / 2μ0 . This criteria is easily met and indeed the CTs traverse the test-stand field. A preliminary experiment on C-2U shows the CT also capable of penetrating into FRC plasmas and refueling is observed resulting in a 20 - 30% increase in total particle number per single-pulsed CT injection. Results from test-stand and C-2U experiments will be presented.

  11. Development of compact linear accelerator in KBSI

    SciTech Connect

    Yoon, Jang-Hee; Lee, Byoung-Seob; Choi, Seyong; Park, Jin Yong; Ok, Jung-Woo; Won, Mi-Sook

    2012-02-15

    The compact linear accelerator using a 28 GHz ECRIS is under construction in KBSI, South Korea. The main capability of this facility is the production of fast neurons for the neutron radiography. The designing of a superconducting magnet, microwave transmission system, beam extraction, and plasma chamber of ECRIS were finished. The nominal axial design fields of the magnets are 3.6 T at injection and 2.2 T at extraction; the nominal radial design field strength at the plasma chamber wall is 2.1 T. We already installed 10 kW, 28 GHz gyrotron, and tested a microwave power from gyrotron using a dummy load. The current status will be discussed in this paper.

  12. Development of compact linear accelerator in KBSI.

    PubMed

    Yoon, Jang-Hee; Lee, Byoung-Seob; Choi, Seyong; Park, Jin Yong; Ok, Jung-Woo; Won, Mi-Sook

    2012-02-01

    The compact linear accelerator using a 28 GHz ECRIS is under construction in KBSI, South Korea. The main capability of this facility is the production of fast neurons for the neutron radiography. The designing of a superconducting magnet, microwave transmission system, beam extraction, and plasma chamber of ECRIS were finished. The nominal axial design fields of the magnets are 3.6 T at injection and 2.2 T at extraction; the nominal radial design field strength at the plasma chamber wall is 2.1 T. We already installed 10 kW, 28 GHz gyrotron, and tested a microwave power from gyrotron using a dummy load. The current status will be discussed in this paper. PMID:22380162

  13. Compact dusty clouds in a cosmic environment

    SciTech Connect

    Tsytovich, V. N.; Ivlev, A. V.; Burkert, A.; Morfill, G. E.

    2014-01-10

    A novel mechanism of the formation of compact dusty clouds in astrophysical environments is discussed. It is shown that the balance of collective forces operating in space dusty plasmas can result in the effect of dust self-confinement, generating equilibrium spherical clusters. The distribution of dust and plasma density inside such objects and their stability are investigated. Spherical dusty clouds can be formed in a broad range of plasma parameters, suggesting that this process of dust self-organization might be a generic phenomenon occurring in different astrophysical media. We argue that compact dusty clouds can represent condensation seeds for a population of small-scale, cold, gaseous clumps in the diffuse interstellar medium. They could play an important role in regulating its small-scale structure and its thermodynamical evolution.

  14. Compact stereo endoscopic camera using microprism arrays.

    PubMed

    Yang, Sung-Pyo; Kim, Jae-Jun; Jang, Kyung-Won; Song, Weon-Kook; Jeong, Ki-Hun

    2016-03-15

    This work reports a microprism array (MPA) based compact stereo endoscopic camera with a single image sensor. The MPAs were monolithically fabricated by using two-step photolithography and geometry-guided resist reflow to form an appropriate prism angle for stereo image pair formation. The fabricated MPAs were transferred onto a glass substrate with a UV curable resin replica by using polydimethylsiloxane (PDMS) replica molding and then successfully integrated in front of a single camera module. The stereo endoscopic camera with MPA splits an image into two stereo images and successfully demonstrates the binocular disparities between the stereo image pairs for objects with different distances. This stereo endoscopic camera can serve as a compact and 3D imaging platform for medical, industrial, or military uses. PMID:26977690

  15. Compost improves compacted urban soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urban construction sites usually result in compacted soils that limit infiltration and root growth. The purpose of this study was to determine if compost, aeration, and/or prairie grasses can remediate a site setup as a simulated post-construction site (compacted). Five years after establishing the ...

  16. The Meaning of a Compact

    ERIC Educational Resources Information Center

    Wasescha, Anna

    2016-01-01

    To mark the 30th anniversary of "Campus Compact," leaders from across the network came together in the summer of 2015 to reaffirm a shared commitment to the public purposes of higher education. Campus Compact's 30th Anniversary Action Statement of Presidents and Chancellors is the product of that collective endeavor. In signing the…

  17. Overview of the compact ignition tokamak

    SciTech Connect

    Flanagan, C.A.

    1986-01-01

    A national team has developed a baseline concept for a Compact Ignition Tokamak (CIT). The CIT mission is to achieve ignition and provide experimental capability to study the behavior of burning plasma. The design uses large magnetic fields on axis (about 10 T) and large plasma currents (about 9-10 MA). The magnet structure derives high strength from the use of a copper-Inconel composite plate design in the nose of region of the toroidal field (TF) coil and in the ohmic heating solenoid. Inertial cooling is used;liquid nitrogen temperatures are established at the beginning of each pulse. Capability is provided to operate either with a divertor or limiter based plasma. The design is very compact (1.32-m major radius, 0.43-m plasma radius), has 16 TF coils, and has 16 major horizontal access ports, about 30 cm by 80 cm, located between TF coils. The schedule is for a construction project to be authorized for the period FY 1988-93.

  18. A compact electron spectrometer for an LWFA.

    SciTech Connect

    Lumpkin, A.; Crowell, R.; Li, Y.; Nemeth, K.

    2007-01-01

    The use of a laser wakefield accelerator (LWFA) beam as a driver for a compact free-electron laser (FEL) has been proposed recently. A project is underway at Argonne National Laboratory (ANL) to operate an LWFA in the bubble regime and to use the quasi-monoenergetic electron beam as a driver for a 3-m-long undulator for generation of sub-ps UV radiation. The Terawatt Ultrafast High Field Facility (TUHFF) in the Chemistry Division provides the 20-TW peak power laser. A compact electron spectrometer whose initial fields of 0.45 T provide energy coverage of 30-200 MeV has been selected to characterize the electron beams. The system is based on the Ecole Polytechnique design used for their LWFA and incorporates the 5-cm-long permanent magnet dipole, the LANEX scintillator screen located at the dispersive plane, a Roper Scientific 16-bit MCP-intensified CCD camera, and a Bergoz ICT for complementary charge measurements. Test results on the magnets, the 16-bit camera, and the ICT will be described, and initial electron beam data will be presented as available. Other challenges will also be addressed.

  19. Acceleration of compact toruses and fusion applications

    SciTech Connect

    Hartman, C.W.; Eddleman, J.L.; Hammer, J.H.; Logan, B.G.; McLean, H.S.; Molvik, A.W.

    1990-10-11

    The Compact Torus (Spheromak-type) is a near ideal plasma confinement configuration for acceleration. The fields are mostly generated by internal plasma currents, plasma confinement is toroidal, and the compact torus exhibits resiliency and stability in virtue of the ``rugged`` helicity invariant. Based on these considerations we are developing a coaxial rail-gun type Compact Torus Accelerator (CTA). In the CTA, the CT ring is formed between coaxial electrodes using a magnetized Marshall gun, it is quasistatically ``precompressed`` in a conical electrode section for inductive energy storage, it is accelerated in a straight-coaxial electrode section as in a conventional rail-gun, and it is focused to small size and high energy and power density in a final ``focus`` cone section. The dynamics of slow precompression and acceleration have been demonstrated experimentally in the RACE device with results in good agreement with 2-D MHD code calculations. CT plasma rings with 100 {micro}gms mass have been accelerated to 40 Kj kinetic energy at 20% efficiency with final velocity = 1 X 10{sup 8} cm/s (= 5 KeV/H{sup +}). Preliminary focus tests exhibi dynamics of radius compression, deceleration, and bouncing. Compression ratios of 2-3 have been achieved. A scaled-up 10-100 MJ CTA is predicted to achieve a focus radius of several cm to deliver = 30 MJ ring kinetic energy in 5-10 nsec. This is sufficient energy, power, and power density to enable the CTA to act as a high efficiency, low cost ICF driver. Alternatively, the focused CT can form the basis for an magnetically insulated, inertial confinement fusion (MICF) system. Preliminary calculations of these fusion systems will be discussed.

  20. Regimes of pulsed formation of a compact plasma configuration with a high energy input

    SciTech Connect

    Romadanov, I. V.; Ryzhkov, S. V.

    2015-10-15

    Results of experiments on the formation of a compact toroidal magnetic configuration at the Compact Toroid Challenge setup are presented. The experiments were primarily aimed at studying particular formation stages. Two series of experiments, with and without an auxiliary capacitor bank, were conducted. The magnetic field was measured, its time evolution and spatial distribution over the chamber volume were determined, and its influence on the formation regimes was investigated.

  1. Magnetic and pH dual responsive core-shell hybrid nanogels: a single nano-object for pH-dependent magnetic manipulation, fluorescent pH-sensing, and drug delivery

    SciTech Connect

    Wu, Weitai; Shen, Jing; Gai, Zheng; Hong, Kunlun; Banerjeea, Probal; Zhou, Shuiqin

    2011-01-01

    Remotely optical sensing and drug delivery using an environmentally-guided magnetically-driven hybrid nanogel particle could allow for medical diagnostics and treatment. Such multifunctional hybrid nanogels (<200 nm) were prepared through the first synthesis of magnetic Ni NPs, followed by a moderate growth of fluorescent metallic Ag on the surface of Ni NPs, and then a coverage of a pH-responsive copolymer gel shell of poly(ethylene glycol-co-methacrylic acid) [p(EG-MAA)] onto the Ni-Ag bimetallic NP cores (18 {+-} 5 nm). The introduction of the pH-responsive p(EG-MAA) gel shell onto the magnetic and fluorescent Ni-Ag NPs makes the polymer-bound Ni-Ag NPs responsive to pH over the physiologically important range 5.0-7.4. The hybrid nanogels can adapt to surrounding pH and regulate the sensitivity in response to external magnetic field (such as a small magnet of 0.1 T), resulting in the accumulation of the hybrid nanogels within the duration from hours to a few seconds as the pH value decreases from 7.4 to 5.0. The pH-dependent magnetic response characteristic of the hybrid nanogels were further integrated with the pH change to fluorescent signal transduction and pH-regulated anticancer drug (a model drug 5-fluorouracil) delivery functions. The hybrid nanogels can overcome cellular barriers to enter the intracellular region and light up the mouse melanoma B16F10 cells. The multiple responsive hybrid nanogel that can be manipulated in tandem endogenous and exogenous activation should enhance our ability to address the complexity of biological systems.

  2. Setting Objectives

    ERIC Educational Resources Information Center

    Elkins, Aaron J.

    1977-01-01

    The author questions the extent to which educators have relied on "relevance" and learner participation in objective-setting in the past decade. He describes a useful approach to learner-oriented evaluation in which content relevance was not judged by participants until after they had been exposed to it. (MF)

  3. A Compact Ring Design with Tunable Momentum Compaction

    SciTech Connect

    Sun, Y.; /SLAC

    2012-05-17

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  4. Decoupling of paramagnetic and ferrimagnetic AMS development during the experimental chemical compaction of illite shale powder

    NASA Astrophysics Data System (ADS)

    Bruijn, Rolf H. C.; Almqvist, Bjarne S. G.; Hirt, Ann M.; Benson, Philip M.

    2013-03-01

    Inclination shallowing of detrital remanent magnetization in sedimentary strata has solely been constrained for the mechanical processes associated with mud deposition and shallow compaction of clay-rich sediment, even though a significant part of mud diagenesis involves chemical compaction. Here we report, for the first time, on the laboratory simulation of magnetic assemblage development in a chemically compacting illite shale powder of natural origin. The experimental procedure comprised three compaction stages that, when combined, simulate the diagenesis and low-grade metamorphism of illite mud. First, the full extent of load-sensitive mechanical compaction is simulated by room temperature dry axial compression. Subsequently, temperature controlled chemical compaction is initiated by exposing the sample in two stages to amphibolite or granulite facies conditions (temperature is 490 to 750°C and confining pressure is 170 or 300 MPa) both in the absence (confining pressure only) and presence of a deformation stress field (axial compression or confined torsion). Thermodynamic equilibrium in the last two compaction stages was not reached, but illite and mica dehydroxylation initiated, thus providing a wet environment. Magnetic properties were characterized by magnetic susceptibility and its anisotropy (AMS) in both high- and low-applied field. Acquisition of isothermal remanent magnetization (IRM), stepwise three-component thermal de-magnetization of IRM and first-order reversal curves were used to characterize the remanence-bearing minerals. During the chemical compaction experiments ferrimagnetic iron-sulphides formed after reduction of magnetite and detrital pyrite in a low sulphur fugacity environment. The degree of low-field AMS is unaffected by porosity reduction from 15 to ˜1 per cent, regardless of operating conditions and compaction history. High-field paramagnetic AMS increases with compaction for all employed stress regimes and conditions, and is

  5. Compact vacuum insulation

    DOEpatents

    Benson, David K.; Potter, Thomas F.

    1992-01-01

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

  6. Compact vacuum insulation

    DOEpatents

    Benson, D.K.; Potter, T.F.

    1992-10-27

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

  7. Compact neutron generator

    DOEpatents

    Leung, Ka-Ngo; Lou, Tak Pui

    2005-03-22

    A compact neutron generator has at its outer circumference a toroidal shaped plasma chamber in which a tritium (or other) plasma is generated. A RF antenna is wrapped around the plasma chamber. A plurality of tritium ion beamlets are extracted through spaced extraction apertures of a plasma electrode on the inner surface of the toroidal plasma chamber and directed inwardly toward the center of neutron generator. The beamlets pass through spaced acceleration and focusing electrodes to a neutron generating target at the center of neutron generator. The target is typically made of titanium tubing. Water is flowed through the tubing for cooling. The beam can be pulsed rapidly to achieve ultrashort neutron bursts. The target may be moved rapidly up and down so that the average power deposited on the surface of the target may be kept at a reasonable level. The neutron generator can produce fast neutrons from a T-T reaction which can be used for luggage and cargo interrogation applications. A luggage or cargo inspection system has a pulsed T-T neutron generator or source at the center, surrounded by associated gamma detectors and other components for identifying explosives or other contraband.

  8. Compact dual-view endoscope without field obscuration

    NASA Astrophysics Data System (ADS)

    Katkam, Rajender; Banerjee, Bhaskar; Huang, Chih Yu; Zhu, Xiaoyin; Ocampo, Luis; Kincade, Jerri-Lynn; Liang, Rongguang

    2015-07-01

    We have developed a compact dual-view endoscopic probe without field obscuration to address the need of simultaneously observing forward and backward fields of view (FOVs) in the colon. The objective is compact with the forward-view and rear-view optical paths sharing the same optical elements. The compact objective is new in that no FOV is blocked. The illumination for forward-view imaging is provided by the cylindrical light guide and backward illumination is achieved with a reflector. We have designed, prototyped, and tested the endoscope by comparing it to a standard clinical colonoscope. We will discuss the system concept, objective design, fabrication of the freeform lens, and test results.

  9. Final report on the LLNL compact torus acceleration project

    SciTech Connect

    Eddleman, J.; Hammer, J.; Hartman, C.; McLean, H.; Molvik, A.

    1995-03-19

    In this report, we summarize recent work at LLNL on the compact torus (CT) acceleration project. The CT accelerator is a novel technique for projecting plasmas to high velocities and reaching high energy density states. The accelerator exploits magnetic confinement in the CT to stably transport plasma over large distances and to directed kinetic energies large in comparison with the CT internal and magnetic energy. Applications range from heating and fueling magnetic fusion devices, generation of intense pulses of x-rays or neutrons for weapons effects and high energy-density fusion concepts.

  10. Solution of the inverse problem of magnetic induction tomography (MIT) with multiple objects: analysis of detectability and statistical properties with respect to the reconstructed conducting region.

    PubMed

    Merwa, Robert; Brunner, Patricia; Missner, Andreas; Hollaus, Karl; Scharfetter, Hermann

    2006-05-01

    Magnetic induction tomography (MIT) is a technique to image the passive electrical properties (i.e. conductivity, permittivity, permeability) of biological tissues. The inverse eddy current problem is nonlinear and ill-posed, thus a Gauss-Newton one-step method in combination with four different regularization schemes is used to obtain stable solutions. Simulations with 16 excitation coils, 32 receiving coils and different spherical perturbations inside a homogeneous cylinder were computed. In order to compare the statistical properties of the reconstructed results a Monte Carlo study with a SNR of 40 dB and 20 dB was carried out. Simulated conductivity perturbations inside a homogeneous cylinder can be localized and resolved and the results prove the feasibility of difference imaging with MIT. PMID:16636415

  11. Overview of the Lockheed Martin Compact Fusion Reactor (CFR) Program

    NASA Astrophysics Data System (ADS)

    McGuire, Thomas

    2015-11-01

    The Lockheed Martin Compact Fusion Reactor (CFR) Program endeavors to quickly develop a compact fusion power plant with favorable commercial economics and military utility. An overview of the concept and its diamagnetic, high beta magnetically encapsulated linear ring cusp confinement scheme will be given. The analytical model of the major loss mechanisms and predicted performance will be discussed, along with the major physics challenges. Key features of an operational CFR reactor will be highlighted. The proposed developmental path following the current experimental efforts will be presented. ©2015 Lockheed Martin Corporation. All Rights Reserved.

  12. Compact modeling of perpendicular nanomagnetic logic based on threshold gates

    NASA Astrophysics Data System (ADS)

    Breitkreutz, Stephan; Eichwald, Irina; Kiermaier, Josef; Csaba, Gyorgy; Schmitt-Landsiedel, Doris; Becherer, Markus

    2014-05-01

    In this work, we show that physical-based compact modeling of perpendicular Nanomagnetic Logic is crucial for the design and simulation of complex circuitry. A compact model for field-coupled nanomagnets based on an Arrhenius switching model and finite element calculations is introduced. As physical parameters have an enormous influence on the behavior of the circuit, their modeling is of great importance. Exemplarily, a 1-bit full adder based on threshold logic gates is analyzed due to its reliability. The obtained findings are used to design a pure magnetic arithmetic logic unit, which can be used for basic Boolean and logic operations.

  13. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  14. Compact radio sources in the galactic plane

    NASA Technical Reports Server (NTRS)

    Jones, Terry Jay; Garwood, Robert; Dickey, John M.

    1988-01-01

    The preliminary results of a search for infrared counterparts to compact continuum radio sources found within 0.5 deg of the Galactic plane are presented. Out of 75 positions searched, nine very red sources, each with a probability of less than 0.01 of being a random field star, were found. Most of the nine sources are characterized by deep silicate absorption features at 10 microns and a red energy distribution that continues to rise beyond 25 microns. Six of the sources are best explained as late O or early B stars exciting a compact H II region. The radio emission is close to that expected for the rate of emission of ionizing photons for a normal main-sequence star. Although these H II regions are compact, they are not sufficiently dusty in the immediate environment of the star to significantly reduce the ionizing flux. Three of the sources show considerably more emission than expected for a main-sequence star, indicating they are either hotter than a main-sequence star with the same luminosity or the radio emision is nonthermal and coming from a more exotic object.

  15. Compact, Reliable EEPROM Controller

    NASA Technical Reports Server (NTRS)

    Katz, Richard; Kleyner, Igor

    2010-01-01

    A compact, reliable controller for an electrically erasable, programmable read-only memory (EEPROM) has been developed specifically for a space-flight application. The design may be adaptable to other applications in which there are requirements for reliability in general and, in particular, for prevention of inadvertent writing of data in EEPROM cells. Inadvertent writes pose risks of loss of reliability in the original space-flight application and could pose such risks in other applications. Prior EEPROM controllers are large and complex and do not provide all reasonable protections (in many cases, few or no protections) against inadvertent writes. In contrast, the present controller provides several layers of protection against inadvertent writes. The controller also incorporates a write-time monitor, enabling determination of trends in the performance of an EEPROM through all phases of testing. The controller has been designed as an integral subsystem of a system that includes not only the controller and the controlled EEPROM aboard a spacecraft but also computers in a ground control station, relatively simple onboard support circuitry, and an onboard communication subsystem that utilizes the MIL-STD-1553B protocol. (MIL-STD-1553B is a military standard that encompasses a method of communication and electrical-interface requirements for digital electronic subsystems connected to a data bus. MIL-STD- 1553B is commonly used in defense and space applications.) The intent was to both maximize reliability while minimizing the size and complexity of onboard circuitry. In operation, control of the EEPROM is effected via the ground computers, the MIL-STD-1553B communication subsystem, and the onboard support circuitry, all of which, in combination, provide the multiple layers of protection against inadvertent writes. There is no controller software, unlike in many prior EEPROM controllers; software can be a major contributor to unreliability, particularly in fault

  16. Compact dc link

    SciTech Connect

    Flairty, C. )

    1991-10-01

    The EPRI Compact Substation Project (a HVDC Converter Station) was developed, designed, and constructed per EPRI Agreement RP213. In December 1983, the converter station operated at its rating (100 MW power transmission and 300 kV dc bias plus 100 kV operating voltage). From January to May 1984, the converter station operated at various power transmission levels. Operation was intermittent due to a randomly occurring voltage breakdown. The voltage breakdown was isolated to the steel tanks containing the thyristor valves in an SF{sub 6} environment. The type of insulators stressed within the valve tanks were: (1) the epoxy cone shape insulators providing an interface to the bus entering the valve tank; (2) epoxy fiberglass hydraulic columns for the flow of the R113 refrigerant to and from the thyristor valves; and (3) the epoxy fiberglass support columns supporting the thyristor valves from the floor of the valve tank. The cause of the randomly occurring breakdown was investigated and determined to be the epoxy fiberglass support columns. The random dielectric breakdowns were due to excessive voltage gradients existing at the epoxy fiberglass support columns. This probably was caused by the misplacement of an internal insert within the column with respect to an external shield on the column. The cost and time to retrofit the support columns outweighed the benefits expected from resuming the project. Consequently, work was terminated and the equipment disassembled. Examination of the epoxy fiberglass support columns revealed several arcing tracks along the inside surface confirming the earlier hypothesis. 53 figs., 32 tabs.

  17. Compact Holographic Data Storage

    NASA Technical Reports Server (NTRS)

    Chao, T. H.; Reyes, G. F.; Zhou, H.

    2001-01-01

    NASA's future missions would require massive high-speed onboard data storage capability to Space Science missions. For Space Science, such as the Europa Lander mission, the onboard data storage requirements would be focused on maximizing the spacecraft's ability to survive fault conditions (i.e., no loss in stored science data when spacecraft enters the 'safe mode') and autonomously recover from them during NASA's long-life and deep space missions. This would require the development of non-volatile memory. In order to survive in the stringent environment during space exploration missions, onboard memory requirements would also include: (1) survive a high radiation environment (1 Mrad), (2) operate effectively and efficiently for a very long time (10 years), and (3) sustain at least a billion write cycles. Therefore, memory technologies requirements of NASA's Earth Science and Space Science missions are large capacity, non-volatility, high-transfer rate, high radiation resistance, high storage density, and high power efficiency. JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Compact Holographic Data Storage (CHDS) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electrooptic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and high-speed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology meeting the high radiation challenge facing the Europa Lander mission. Additional information is contained in the original extended abstract.

  18. FIR galaxies with compact radio cores

    NASA Astrophysics Data System (ADS)

    Chini, R.; Biermann, P. L.; Kreysa, E.; Kuhr, H.; Mezger, P. G.; Schmidt, J.; Witzel, A.; Zensus, J. A.

    1987-07-01

    Comparing the IRAS point-source catalog (1985) with sources detected in a VLBI extragalactic radio source survey (Zensus et al., 1984), five FIR sources are found which all show compact radio cores. These objects have been observed with the 30-m MRT at Pico Veleta (Spain) at 1.2-mm wavelength to provide spectral coverage between IRAS and radio bands. The two galaxies among the five sources have luminosities of order 10 to the 12th solar luminosities in the FIR and thus may be super star bursters similar to Arp 220. On the other hand, all five objects have active galactic nuclei, and so the FIR luminosities may be powered by the nuclear activity. Since flat-spectrum radio sources have compact nuclear components, the 1-Jy catalog and its extension to lower flux densities (Kuehr et al., 1979 and 1981) are compared with the IRAS catalog, and a small number of additional active nuclei with strong emission in the FIR are identified. These objects can serve to study the competition between starbursts and nuclear activity to explain high FIR luminosities.

  19. VLA neutral hydrogen imaging of compact groups

    NASA Technical Reports Server (NTRS)

    Williams, B. A.; Mcmahon, P. M.; Vangorkom, J. H.

    1990-01-01

    Images of the neutral hydrogen (H I) in the direction of the compact groups of galaxies, HCG 31, HCG 44, and HCG 79 are presented. The authors find in HCG 31 and HCG 79, emission contained within a cloud much larger than the galaxies as well as the entire group. The H I emission associated with HCG 44 is located within the individual galaxies but shows definite signs of tidal interactions. The authors imaged the distribution and kinematics of neutral hydrogen at the two extremes of group sizes represented in Hickson's sample. HCG 44 is at the upper limit while HCG 18, HCG 31, and HCG 79 are at the lower end. Although the number of groups that have been imaged is still very small, there may be a pattern emerging which describes the H I morphology of compact groups. The true nature of compact groups has been the subject of considerable debate and controversy. The most recent observational and theoretical evidence strongly suggests that compact groups are physically dense, dynamical systems that are in the process of merging into a single object (Williams and Rood 1987, Hickson and Rood 1988, Barnes 1989). The neutral hydrogen deficiency observed by Williams and Rood (1987) is consistent with a model in which frequent galactic collisions and interactions have heated some of the gas during the short lifetime of the group. The H I disks which are normally more extended than the luminous ones are expected to be more sensitive to collisions and to trace the galaxy's response to recent interactions. Very Large Array observations can provide in most cases the spatial resolution needed to confirm the dynamical interactions in these systems.

  20. Optical identifications of southern compact radio sources

    NASA Technical Reports Server (NTRS)

    Jauncey, David L.; Savage, Ann; Morabito, David D.; Preston, Robert A.; Nicolson, George C.

    1989-01-01

    Optical identifications are presented for 158 radio sources, mostly from the Southern Hemisphere, based on the coincidence between the position of the optical object and the compact milliarcsecond radio nucleus. Radio positions with an accuracy of typically 0.3 arcsec rms were measured from the observed delay and fringe rate of VLBI observations at 2.29 GHz on an Australia-to-South Africa baseline. Optical identifications and positions were measured from the UK Schmidt Telescope deep IIIa-J Southern Sky Survey plates, where available.