Characteristics of the NASA Lewis bumpy-torus plasma generated with positive applied potentials

NASA Technical Reports Server (NTRS)

Roth, J. R.; Gerdin, G. A.; Richardson, R. W.

1976-01-01

Experimental observations were made during steady-state operation of a bumpy-torus plasma at input powers up to 150 kW in deuterium and helium gas and with positive potentials applied to the midplane electrodes. In this steady-state ion heating method a modified Penning discharge is operated such that the plasma is acted upon by a combination of strong electric and magnetic fields. Experimental investigation of a deuterium plasma revealed electron temperatures from 14 to 140 eV and ion kinetic temperatures from 160 to 1785 eV. At least two distinct modes of operation exist. Experimental data shows that the average ion residence time in the plasma is virtually independent of the magnetic field strength. Data was taken when all 12 anode rings were at high voltage, and in other symmetric configurations in which the toroidal plasma was generated by applying positive potentials to six anode rings, three anode rings, and a single anode ring.

A fluctuation-induced plasma transport diagnostic based upon fast-Fourier transform spectral analysis

NASA Technical Reports Server (NTRS)

Powers, E. J.; Kim, Y. C.; Hong, J. Y.; Roth, J. R.; Krawczonek, W. M.

1978-01-01

A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented.

Inward transport of a toroidally confined plasma subject to strong radial electric fields

NASA Technical Reports Server (NTRS)

Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J.; Kim, Y.

1977-01-01

The paper aims at showing that the density and confinement time of a toroidal plasma can be enhanced by radial electric fields far stronger than the ambipolar values, and that, if such electric fields point into the plasma, radially inward transport can result. The investigation deals with low-frequency fluctuation-induced transport using digitally implemented spectral analysis techniques and with the role of strong applied radial electric fields and weak vertical magnetic fields on plasma density and particle confinement times in a Bumpy Torus geometry. Results indicate that application of sufficiently strong radially inward electric fields results in radially inward fluctuation-induced transport into the toroidal electrostatic potential well; this inward transport gives rise to higher average electron densities and longer particle confinement times in the toroidal plasma.

EBT reactor systems analysis and cost code: description and users guide (Version 1)

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

Santoro, R.T.; Uckan, N.A.; Barnes, J.M.

1984-06-01

An ELMO Bumpy Torus (EBT) reactor systems analysis and cost code that incorporates the most recent advances in EBT physics has been written. The code determines a set of reactors that fall within an allowed operating window determined from the coupling of ring and core plasma properties and the self-consistent treatment of the coupled ring-core stability and power balance requirements. The essential elements of the systems analysis and cost code are described, along with the calculational sequences leading to the specification of the reactor options and their associated costs. The input parameters, the constraints imposed upon them, and the operatingmore » range over which the code provides valid results are discussed. A sample problem and the interpretation of the results are also presented.« less

Alternative approaches to plasma confinement

NASA Technical Reports Server (NTRS)

Roth, J. R.

1977-01-01

The potential applications of fusion reactors, the desirable properties of reactors intended for various applications, and the limitations of the Tokamak concept are discussed. The principles and characteristics of 20 distinct alternative confinement concepts are described, each of which may be an alternative to the Tokamak. The devices are classed as Tokamak-like, stellarator-like, mirror machines, bumpy tori, electrostatically assisted, migma concept, and wall-confined plasma.

Evaluation of performance of select fusion experiments and projected reactors

NASA Technical Reports Server (NTRS)

Miley, G. H.

1978-01-01

The performance of NASA Lewis fusion experiments (SUMMA and Bumpy Torus) is compared with other experiments and that necessary for a power reactor. Key parameters cited are gain (fusion power/input power) and the time average fusion power, both of which may be more significant for real fusion reactors than the commonly used Lawson parameter. The NASA devices are over 10 orders of magnitude below the required powerplant values in both gain and time average power. The best experiments elsewhere are also as much as 4 to 5 orders of magnitude low. However, the NASA experiments compare favorably with other alternate approaches that have received less funding than the mainline experiments. The steady-state character and efficiency of plasma heating are strong advantages of the NASA approach. The problem, though, is to move ahead to experiments of sufficient size to advance in gain and average power parameters.

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

Sager, P.H.

Studies were carried out on the FED Baseline to improve design definition, establish feasibility, and reduce cost. Emphasis was placed on cost reduction, but significant feasibility concerns existed in several areas, and better design definition was required to establish feasibility and provide a better basis for cost estimates. Design definition and feasibility studies included the development of a labyrinth shield ring concept to prevent radiation streaming between the torus spool and the TF coil cryostat. The labyrinth shield concept which was developed reduced radiation streaming sufficiently to permit contact maintenance of the inboard EF coils. Various concepts of preventing arcingmore » between adjacent shield sectors were also explored. It was concluded that installation of copper straps with molybdenum thermal radiation shields would provide the most reliable means of preventing arcing. Other design studies included torus spool electrical/structural concepts, test module shielding, torus seismic response, poloidal conditions in the magnets, disruption characteristics, and eddy current effects. These additional studies had no significant impact on cost but did confirm the feasibility of the basic FED Baseline concept.« less

Multipole moments of bumpy black holes

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

Vigeland, Sarah J.

General relativity predicts the existence of black holes, compact objects whose spacetimes depend only on their mass, spin, and charge in vacuum (the 'no-hair' theorem). As various observations probe deeper into the strong fields of black hole candidates, it is becoming possible to test this prediction. Previous work suggested that such tests can be performed by measuring whether the multipolar structure of black hole candidates has the form that general relativity demands, and introduced a family of 'bumpy black hole' spacetimes to be used for making these measurements. These spacetimes have generalized multipoles, where the deviation from the Kerr metricmore » depends on the spacetime's 'bumpiness'. In this paper, we show how to compute the Geroch-Hansen moments of a bumpy black hole, demonstrating that there is a clean mapping between the deviations used in the bumpy black hole formalism and the Geroch-Hansen moments. We also extend our previous results to define bumpy black holes whose current moments, analogous to magnetic moments of electrodynamics, deviate from the canonical Kerr value.« less

Experimental and simulation of split semi-torus key in PVC foam core to improve the debonding resistance of composite sandwich panel

NASA Astrophysics Data System (ADS)

Juliyana, M.; Santhana Krishnan, R.

2018-02-01

The sandwich composite panels consisting of facesheet and core material are used as a primary structural member for aerospace, civil and marine areas due to its high stiffness to weight ratio. But the debonding nature of facesheet from the foam core under shear loading conditions leads to failure of the composite structure. To inhibit the debonding, an innovative methodology of introducing semi-torus key is used in the present study. The polyvinyl chloride foam core(PVC) is grooved and filled with semi-torus shaped chopped strand prepregs which are sandwiched between alternate layers of woven roven(WR) and chopped strand mat(CSM) skins by vacuum infusion process. The sandwich panel manufactured with semi-torus keys is evaluated regarding experimental and numerical simulations under shear loading conditions. The present innovative concept delays the debonding between face-sheet and foam core with enhancement the shear load carrying capability as the initial stiffness is higher than the conventional model. Also, the shear behaviour of the proposed concept is in good agreement with experimental results. The split semi-torus keys sustain the shear failure resulting in resistance to debonding capability.

Electron microscopic observations of hydrogen implantation in ilmenites

NASA Technical Reports Server (NTRS)

Blanford, G. E.

1983-01-01

Hydrogen ion beams were found to form submicrometer, bumpy textures on the surface of ilmenite grains. From this effect, it is believed that similar bumpy textures seen on lunar ilmenite, pyroxene, and olivine grains are likely to be caused by solar wind irradiation. As a consequence, the concentration of bumpy textured grains may be a useful index of surface maturity for lunar soils. An attempt was made to search for grains with these bumpy textures in interplanetary dust and lunar and meteoritic regolith breccias in order to obtain information about the duration of their exposure to the solar wind. Solar wind irradiation was simulated on natural, terrestrial ilmenite. Hydrogen ion beams were directed at small grains and polished sections which were then examined by electron microscopy.

A model for particle confinement in a toroidal plasma subject to strong radial electric fields

NASA Technical Reports Server (NTRS)

Roth, J. R.

1977-01-01

The approach adopted in the NASA Lewis Bumpy Torus experiment is to confine and heat a toroidal plasma by the simultaneous application of strong dc magnetic fields and electric fields. Strong radial electric fields (about 1 kV/cm) are imposed by biasing the plasma with up to 12 negative electrode rings which surround its minor circumference. The plasma containment is consistent with a balance of two processes: a radial infusion of ions in those sectors not containing electrode rings, resulting from the radially inward electric fields; and ion losses to the electrode rings, each of which acts as a sink and draws ions out the plasma in the manner of a Langmuir probe in the ion saturation regime. The highest density on axis which has been observed so far in this steady-state plasma is 6.2 trillion particles per cu cm, for which the particle containment time is 2.5 msec. The deuterium ion kinetic temperature for these conditions was in the range of 360 to 520 eV.

FLIT: Flowing LIquid metal Torus

NASA Astrophysics Data System (ADS)

Kolemen, Egemen; Majeski, Richard; Maingi, Rajesh; Hvasta, Michael

2017-10-01

The design and construction of FLIT, Flowing LIquid Torus, at PPPL is presented. FLIT focuses on a liquid metal divertor system suitable for implementation and testing in present-day fusion systems, such as NSTX-U. It is designed as a proof-of-concept fast-flowing liquid metal divertor that can handle heat flux of 10 MW/m2 without an additional cooling system. The 72 cm wide by 107 cm tall torus system consisting of 12 rectangular coils that give 1 Tesla magnetic field in the center and it can operate for greater than 10 seconds at this field. Initially, 30 gallons Galinstan (Ga-In-Sn) will be recirculated using 6 jxB pumps and flow velocities of up to 10 m/s will be achieved on the fully annular divertor plate. FLIT is designed as a flexible machine that will allow experimental testing of various liquid metal injection techniques, study of flow instabilities, and their control in order to prove the feasibility of liquid metal divertor concept for fusion reactors. FLIT: Flowing LIquid metal Torus. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.

Self-cooled liquid-metal blanket concept

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

Malang, S.; Arheidt, K.; Barleon, L.

1988-11-01

A blanket concept for the Next European Torus (NET) where 83Pb-17Li serves both as breeder material and as coolant is described. The concept is based on the use of novel flow channel inserts for a decisive reduction of the magnetohydrodynamic (MHD) pressure drop and employs beryllium as neutron multiplier in order to avoid the need for breeding blankets at the inboard side of the torus. This study includes the design, neutronics, thermal hydraulics, stresses, MHDs, corrosion, tritium recovery, and safety of a self-cooled liquid-metal blanket. The results of the investigations indicate that the self-cooled blanket is an attractive alternative tomore » other driver blanket concepts for NET and that it can be extrapolated to the conditions of a DEMO reactor.« less

Low-frequency fluctuation spectra and associated particle transport in the NASA Lewis bumpy-torus plasma

NASA Technical Reports Server (NTRS)

Singh, C. M.; Krawczonek, W. M.; Roth, J. R.; Hong, J. Y.; Kim, Y. C.; Powers, E. J.

1978-01-01

The strong radial electric field associated with the Penning discharge and the strong toroidal magnetic field give rise to a diversity of E/B phenomena, such as rotating waves and spokes, which in turn manifest themselves as space-time fluctuations of the plasma density and potential. Work is done to further understand the nature and origin of the fluctuations and their connection with fluctuation-induced transport. The approach is to monitor the density and potential fluctuations; to digitize the data; and to generate, with the aid of a computer, various spectral properties by means of the fast fourier transform. Of particular interest is the computer-generated transport spectrum that indicates in a quantitative way which fluctuation spectral components contribute to transport and which do not. All experimental measurements of the spectral characteristics of the plasma are given in absolute units rather than as relative values. Preliminary measurements of the transport spectrum of the ion population are given, and it is shown that the fluctuation-induced transport is in order-of-magnitude agreement with that inferred from the steady state current flowing to the electrodes that generate the plasma.

Quasar Drenched in Water Vapor Artist Concept

NASA Image and Video Library

2012-08-31

Artist concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below.

IRIS - A concept for microwave sensing of soil moisture and ocean salinity

NASA Technical Reports Server (NTRS)

Moghaddam, M.; Njoku, E.

1997-01-01

A concept is described for passive microwave sensing of soil moisture and ocean salinity from space. The Inflatable Radiometric Imaging System (IRIS) makes use of a large-diameter, offset-fed, parabolic-torus antenna with multiple feeds, in a conical pushbroom configuration.

A Bumpy Border Crossing into the Teaching Culture on a U.S. Campus: Experience of a Chinese Faculty Member

ERIC Educational Resources Information Center

Cheng, Qiang; Wang, Jian; Zhang, Shaoan

2013-01-01

Guided by cultural border crossing and teacher identity development theories, this case study explores the bumpy process of a junior Chinese faculty member's border crossing into the U.S. teaching culture and analyzes the challenges, coping strategies, and consequences of his border crossing on teaching and teacher identity development. The…

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 from an astrophysical source, observations should be able to test this hypothesis, stringently testing whether they are in fact the black holes of general relativity.

Spacetime and orbits of bumpy black holes

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

Vigeland, Sarah J.; Hughes, Scott A.

2010-01-15

Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced ''bumpy black holes'': objects that are almost, but not quite, general relativity's black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation ismore » zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes--objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime's bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track the orbital phase of a small orbiting body. We find that in the weak field, orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is many times greater than would be predicted from a Newtonian analysis, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime's multipoles deviate from the black hole expectation.« less

Elmo bumpy square plasma confinement device

DOEpatents

Owen, L.W.

1985-01-01

The invention is an Elmo bumpy type plasma confinement device having a polygonal configuration of closed magnet field lines for improved plasma confinement. In the preferred embodiment, the device is of a square configuration which is referred to as an Elmo bumpy square (EBS). The EBS is formed by four linear magnetic mirror sections each comprising a plurality of axisymmetric assemblies connected in series and linked by 90/sup 0/ sections of a high magnetic field toroidal solenoid type field generating coils. These coils provide corner confinement with a minimum of radial dispersion of the confined plasma to minimize the detrimental effects of the toroidal curvature of the magnetic field. Each corner is formed by a plurality of circular or elliptical coils aligned about the corner radius to provide maximum continuity in the closing of the magnetic field lines about the square configuration confining the plasma within a vacuum vessel located within the various coils forming the square configuration confinement geometry.

An Unwelcome Place for New Stars (artist concept)

NASA Technical Reports Server (NTRS)

2006-01-01

[figure removed for brevity, see original site] Poster Version Suppression of Star Formation from Supermassive Black Holes

This artist's concept depicts a supermassive black hole at the center of a galaxy. NASA's Galaxy Evolution Explorer found evidence that black holes -- once they grow to a critical size -- stifle the formation of new stars in elliptical galaxies. Black holes are thought to do this by heating up and blasting away the gas that fuels star formation.

The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Beyond the torus, only the old red-colored stars that make up the galaxy can be seen. There are no new stars in the galaxy.

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

Peng, Y.K.M.; Strickler, D.J.

The spherical torus is a very small aspect ratio (A < 2) confinement concept obtained by retaining only the indispensable components inboard to the plasma torus. MHD equilibrium calculations show that spherical torus plasmas with safety factor q > 2 are characterized by high toroidal beta (..beta../sub t/ > 0.2), low poloidal beta (..beta../sub p/ < 0.3), naturally large elongation (kappa greater than or equal to 2), large plasma current with I/sub p//(aB/sub t0/) up to about 7 MA/mT, strong paramagnetism (B/sub t//B/sub t0/ > 1.5), and strong plasma helicity (F comparable to THETA). A large near-omnigeneous region is seenmore » at the large-major-radius, bad-curvature region of the plasma in comparison with the conventional tokamaks. These features combine to engender the spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost. Because of its strong paramagnetism and helicity, the spherical torus plasma shares some of the desirable features of spheromak and reversed-field pinch (RFP) plasmas, but with tokamak-like confinement and safety factor q. The general class of spherical tori, which includes the spherical tokamak (q > 1), the spherical pinch (1 > q > O), and the spherical RFP (q < O), have magnetic field configurations unique in comparison with conventional tokamaks and RFPs. 22 refs., 12 figs.« less

Dynamic Characterization of an Inflatable Concentrator for Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Leigh, Larry M.; Tinker, Michael L.; McConnaughey, Paul (Technical Monitor)

2002-01-01

Solar-thermal propulsion is a concept for producing thrust sufficient for orbital transfers and requires innovative, lightweight structures. This note presents a description of an inflatable concentrator that consists of a torus, lens simulator, and three tapered struts. Modal testing was discussed for characterization and verification of the solar concentrator assembly. Finite element shell models of the concentrator were developed using a two-step nonlinear approach, and results were compared to test data. Reasonable model-to-test agreement was achieved for the torus, and results for the concentrator assembly were comparable to the test for several modes.

Realizing "2001: A Space Odyssey": Piloted Spherical Torus Nuclear Fusion Propulsion

NASA Technical Reports Server (NTRS)

Williams, Craig H.; Dudzinski, Leonard A.; Borowski, Stanley K.; Juhasz, Albert J.

2005-01-01

A conceptual vehicle design enabling fast, piloted outer solar system travel was created predicated on a small aspect ratio spherical torus nuclear fusion reactor. The initial requirements were satisfied by the vehicle concept, which could deliver a 172 mt crew payload from Earth to Jupiter rendezvous in 118 days, with an initial mass in low Earth orbit of 1,690 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including artificial gravity payload, central truss, nuclear fusion reactor, power conversion, magnetic nozzle, fast wave plasma heating, tankage, fuel pellet injector, startup/re-start fission reactor and battery bank, refrigeration, reaction control, communications, mission design, and space operations. Detailed fusion reactor design included analysis of plasma characteristics, power balance/utilization, first wall, toroidal field coils, heat transfer, and neutron/x-ray radiation. Technical comparisons are made between the vehicle concept and the interplanetary spacecraft depicted in the motion picture 2001: A Space Odyssey.

Exploration of spherical torus physics in the NSTX device

NASA Astrophysics Data System (ADS)

Ono, M.; Kaye, S. M.; Peng, Y.-K. M.; Barnes, G.; Blanchard, W.; Carter, M. D.; Chrzanowski, J.; Dudek, L.; Ewig, R.; Gates, D.; Hatcher, R. E.; Jarboe, T.; Jardin, S. C.; Johnson, D.; Kaita, R.; Kalish, M.; Kessel, C. E.; Kugel, H. W.; Maingi, R.; Majeski, R.; Manickam, J.; McCormack, B.; Menard, J.; Mueller, D.; Nelson, B. A.; Nelson, B. E.; Neumeyer, C.; Oliaro, G.; Paoletti, F.; Parsells, R.; Perry, E.; Pomphrey, N.; Ramakrishnan, S.; Raman, R.; Rewoldt, G.; Robinson, J.; Roquemore, A. L.; Ryan, P.; Sabbagh, S.; Swain, D.; Synakowski, E. J.; Viola, M.; Williams, M.; Wilson, J. R.; NSTX Team

2000-03-01

The National Spherical Torus Experiment (NSTX) is being built at Princeton Plasma Physics Laboratory to test the fusion physics principles for the spherical torus concept at the MA level. The NSTX nominal plasma parameters are R0 = 85 cm, a = 67 cm, R/a >= 1.26, Bt = 3 kG, Ip = 1 MA, q95 = 14, elongation κ <= 2.2, triangularity δ <= 0.5 and a plasma pulse length of up to 5 s. The plasma heating/current drive tools are high harmonic fast wave (6 MW, 5 s), neutral beam injection (5 MW, 80 keV, 5 s) and coaxial helicity injection. Theoretical calculations predict that NSTX should provide exciting possibilities for exploring a number of important new physics regimes, including very high plasma β, naturally high plasma elongation, high bootstrap current fraction, absolute magnetic well and high pressure driven sheared flow. In addition, the NSTX programme plans to explore fully non-inductive plasma startup as well as a dispersive scrape-off layer for heat and particle flux handling.

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

Stewart Zweben; Samuel Cohen; Hantao Ji

Small ''concept exploration'' experiments have for many years been an important part of the fusion research program at the Princeton Plasma Physics Laboratory (PPPL). this paper describes some of the present and planned fusion concept exploration experiments at PPPL. These experiments are a University-scale research level, in contrast with the larger fusion devices at PPPL such as the National Spherical Torus Experiment (NSTX) and the Tokamak Fusion Test Reactor (TFTR), which are at ''proof-of-principle'' and ''proof-of-performance'' levels, respectively.

Performance of hydrofoils with humpback whale-like leading edge protuberances.

NASA Astrophysics Data System (ADS)

Levshin, Alexandra; Henoch, Charles; Johari, Hamid

2005-11-01

The humpback whale (Megaptera novaeangliae) is extremely maneuverable, compared to other whale species, despite its large size and rigid body. Turning maneuvers are especially evident during pursuit of prey. The agility of humpback whale has been attributed to their use of pectoral flippers. The thick flippers have large aspect ratios, and large scale protuberances are present on the leading edge. The flippers do not flap during turning maneuvers. The cross-section of the flipper has a profile similar to a NACA 634-021 airfoil. The amplitude of leading edge protuberances ranges from 2.5 to 12% of the chord, with a spanwise extent of 10 to 50% the chord depending on the location along the span. It has been hypothesized that the `bumpy' leading edge is used for flow control. To examine the effects of protuberances on the leading edge of hydrofoils, a series of rectangular foils with bumpy leading edges were manufactured. The leading edge is sinusoidal in the spanwise direction with amplitudes and wavelengths comparable to that of humpback whale's flippers. The forces and moments on these bumpy foils were measured in a water tunnel and compared with a smooth leading edge foil.

Reverse-Bumpy-Ball-Type-Nanoreactor-Loaded Nylon Membranes as Peroxidase-Mimic Membrane Reactors for a Colorimetric Assay for H₂O₂.

PubMed

Tong, Ying; Jiao, Xiangyu; Yang, Hankun; Wen, Yongqiang; Su, Lei; Zhang, Xueji

2016-04-01

Herein we report for the first time fabrication of reverse bumpy ball (RBB)-type-nanoreactor-based flexible peroxidase-mimic membrane reactors (MRs). The RBB-type nanoreactors with gold nanoparticles embedded in the inner walls of carbon shells were loaded on nylon membranes through a facile filtration approach. The as-prepared flexible catalytic membrane was studied as a peroxidase-mimic MR. It was found that the obtained peroxidase-mimic MR could exhibit several advantages over natural enzymes, such as facile and good recyclability, long-term stability and easy storage. Moreover, the RBB NS-modified nylon MRs as a peroxidase mimic provide a useful colorimetric assay for H₂O₂.

Exploration of high harmonic fast wave heating on the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Wilson, J. R.; Bell, R. E.; Bernabei, S.; Bitter, M.; Bonoli, P.; Gates, D.; Hosea, J.; LeBlanc, B.; Mau, T. K.; Medley, S.; Menard, J.; Mueller, D.; Ono, M.; Phillips, C. K.; Pinsker, R. I.; Raman, R.; Rosenberg, A.; Ryan, P.; Sabbagh, S.; Stutman, D.; Swain, D.; Takase, Y.; Wilgen, J.

2003-05-01

High harmonic fast wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [M. Ono, S. M. Kaye, S. Neumeyer et al., in Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999 (IEEE, Piscataway, NJ, 1999), p. 53] is such a device. An rf heating system has been installed on the NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.

Fractional Klein-Gordon equation composed of Jumarie fractional derivative and its interpretation by a smoothness parameter

NASA Astrophysics Data System (ADS)

Ghosh, Uttam; Banerjee, Joydip; Sarkar, Susmita; Das, Shantanu

2018-06-01

Klein-Gordon equation is one of the basic steps towards relativistic quantum mechanics. In this paper, we have formulated fractional Klein-Gordon equation via Jumarie fractional derivative and found two types of solutions. Zero-mass solution satisfies photon criteria and non-zero mass satisfies general theory of relativity. Further, we have developed rest mass condition which leads us to the concept of hidden wave. Classical Klein-Gordon equation fails to explain a chargeless system as well as a single-particle system. Using the fractional Klein-Gordon equation, we can overcome the problem. The fractional Klein-Gordon equation also leads to the smoothness parameter which is the measurement of the bumpiness of space. Here, by using this smoothness parameter, we have defined and interpreted the various cases.

Plasma transport in the Io torus - The importance of microscopic diffusion

NASA Technical Reports Server (NTRS)

Mei, YI; Thorne, Richard M.

1991-01-01

This paper considers the question of whether the distribution of mass in the Io plasma torus is consistent with the concept of interchange eddy transport. Specifically, the flux tube content exhibits a gradual decrease with increasing radial distance from the source near Io without any evidence for substantial density irregularity associated with the plasma source or loss. Using a simple one-dimensional numerical model to simulate macroscopic interchange eddy transport, it is demonstrated that this smooth equilibrium distribution of mass can occur but only with the inclusion of a minimal level of small scale microscopic mixing at a rate approaching Bohm diffusion. Otherwise, the system exhibits a chaotic appearance which never approaches an equilibrium distribution. Various physical mechanisms for the microscopic diffusion process which is required to provide a sufficiently rapid mixing of material between the macroscopic eddies are discussed.

Final technical report

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

Richman, M.

1996-08-01

Granular flows of nearly elastic, identical spheres down bumpy inclines are described. A numerical technique is developed to overcome the difficulties associated with the ill-defined `tops` of these flows.

Drift resonance and stability of the Io plasma torus

NASA Astrophysics Data System (ADS)

Zhan, Jie; Hill, T. W.

2000-03-01

The observed local time asymmetry of the Io plasma torus is generally attributed to the presence of a persistent dawn-to-dusk electric field in the Jovian magnetosphere. The local time asymmetry is modulated at the System 3 rotation period of Jupiter's magnetic field, suggesting that the dawn-to-dusk electric field may be similarly modulated. We argue that such a System 3 modulation would have a profound disruptive effect on the observed torus structure if the torus were to corotate at exactly the System 3 rate: the torus would be a resonantly forced harmonic oscillator, and would disintegrate in a few rotation periods, contrary to observations. This destabilizing effect is independent of, and in addition to, the more familiar effect of the centrifugal interchange instability, which is also capable of disrupting the torus in a few rotation periods in the absence of other effects. We conclude that the observed (few percent) corotation lag of the torus is essential to preserving the observed long-lived torus structure by detuning the resonant frequency (the torus drift frequency) relative to the forcing frequency (System 3). A possible outcome of this confinement mechanism is a residual radial oscillation of the torus at the beat period (~10 days) between System 3 and the torus drift period.

Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

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

J.R. Wilson; R.E. Bell; S. Bernabei

2003-02-11

High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the STmore » concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.« less

Particle orbits in a force-balanced, wave-driven, rotating torus

DOE PAGES

Ochs, I. E.; Fisch, N. J.

2017-09-01

A wave-driven rotating torus is a recently proposed fusion concept where the rotational transform is provided by the E × B drift resulting from a minor radial electric field. This field can be produced, for instance, by the RF-wave-mediated extraction of fusion-born alpha particles. In this paper, we discuss how macroscopic force balance, i.e., balance of the thermal hoop force, can be achieved in such a device. We show that this requires the inclusion of a small plasma current and vertical magnetic field and identify the desirable reactor regime through free energy considerations. We then analyze particle orbits in thismore » desirable regime, identifying velocity-space anisotropies in trapped (banana) orbits, resulting from the cancellation of rotational transforms due to the radial electric and poloidal magnetic fields. The potential neoclassical effects of these orbits on the perpendicular conductivity, current drive, and transport are discussed.« less

Particle orbits in a force-balanced, wave-driven, rotating torus

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

Ochs, I. E.; Fisch, N. J.

A wave-driven rotating torus is a recently proposed fusion concept where the rotational transform is provided by the E × B drift resulting from a minor radial electric field. This field can be produced, for instance, by the RF-wave-mediated extraction of fusion-born alpha particles. In this paper, we discuss how macroscopic force balance, i.e., balance of the thermal hoop force, can be achieved in such a device. We show that this requires the inclusion of a small plasma current and vertical magnetic field and identify the desirable reactor regime through free energy considerations. We then analyze particle orbits in thismore » desirable regime, identifying velocity-space anisotropies in trapped (banana) orbits, resulting from the cancellation of rotational transforms due to the radial electric and poloidal magnetic fields. The potential neoclassical effects of these orbits on the perpendicular conductivity, current drive, and transport are discussed.« less

Particle orbits in a force-balanced, wave-driven, rotating torus

NASA Astrophysics Data System (ADS)

Ochs, I. E.; Fisch, N. J.

2017-09-01

A wave-driven rotating torus is a recently proposed fusion concept where the rotational transform is provided by the E × B drift resulting from a minor radial electric field. This field can be produced, for instance, by the RF-wave-mediated extraction of fusion-born alpha particles. In this paper, we discuss how macroscopic force balance, i.e., balance of the thermal hoop force, can be achieved in such a device. We show that this requires the inclusion of a small plasma current and vertical magnetic field and identify the desirable reactor regime through free energy considerations. We then analyze particle orbits in this desirable regime, identifying velocity-space anisotropies in trapped (banana) orbits, resulting from the cancellation of rotational transforms due to the radial electric and poloidal magnetic fields. The potential neoclassical effects of these orbits on the perpendicular conductivity, current drive, and transport are discussed.

A Spherical Torus Nuclear Fusion Reactor Space Propulsion Vehicle Concept for Fast Interplanetary Travel

NASA Technical Reports Server (NTRS)

Williams, Craig H.; Borowski, Stanley K.; Dudzinski, Leonard A.; Juhasz, Albert J.

1998-01-01

A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a greater than 5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all ma or systems including payload, central truss, nuclear reactor (including divertor and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, power utilization, and component design.

A new equilibrium torus solution and GRMHD initial conditions

NASA Astrophysics Data System (ADS)

Penna, Robert F.; Kulkarni, Akshay; Narayan, Ramesh

2013-11-01

Context. General relativistic magnetohydrodynamic (GRMHD) simulations are providing influential models for black hole spin measurements, gamma ray bursts, and supermassive black hole feedback. Many of these simulations use the same initial condition: a rotating torus of fluid in hydrostatic equilibrium. A persistent concern is that simulation results sometimes depend on arbitrary features of the initial torus. For example, the Bernoulli parameter (which is related to outflows), appears to be controlled by the Bernoulli parameter of the initial torus. Aims: In this paper, we give a new equilibrium torus solution and describe two applications for the future. First, it can be used as a more physical initial condition for GRMHD simulations than earlier torus solutions. Second, it can be used in conjunction with earlier torus solutions to isolate the simulation results that depend on initial conditions. Methods: We assume axisymmetry, an ideal gas equation of state, constant entropy, and ignore self-gravity. We fix an angular momentum distribution and solve the relativistic Euler equations in the Kerr metric. Results: The Bernoulli parameter, rotation rate, and geometrical thickness of the torus can be adjusted independently. Our torus tends to be more bound and have a larger radial extent than earlier torus solutions. Conclusions: While this paper was in preparation, several GRMHD simulations appeared based on our equilibrium torus. We believe it will continue to provide a more realistic starting point for future simulations.

Generic torus canards

NASA Astrophysics Data System (ADS)

Vo, Theodore

2017-10-01

Torus canards are special solutions of fast/slow systems that alternate between attracting and repelling manifolds of limit cycles of the fast subsystem. A relatively new dynamic phenomenon, torus canards have been found in neural applications to mediate the transition from tonic spiking to bursting via amplitude-modulated spiking. In R3, torus canards are degenerate: they require one-parameter families of 2-fast/1-slow systems in order to be observed and even then, they only occur on exponentially thin parameter intervals. The addition of a second slow variable unfolds the torus canard phenomenon, making it generic and robust. That is, torus canards in fast/slow systems with (at least) two slow variables occur on open parameter sets. So far, generic torus canards have only been studied numerically, and their behaviour has been inferred based on averaging and canard theory. This approach, however, has not been rigorously justified since the averaging method breaks down near a fold of periodics, which is exactly where torus canards originate. In this work, we combine techniques from Floquet theory, averaging theory, and geometric singular perturbation theory to show that the average of a torus canard is a folded singularity canard. In so doing, we devise an analytic scheme for the identification and topological classification of torus canards in fast/slow systems with two fast variables and k slow variables, for any positive integer k. We demonstrate the predictive power of our results in a model for intracellular calcium dynamics, where we explain the mechanisms underlying a novel class of elliptic bursting rhythms, called amplitude-modulated bursting, by constructing the torus canard analogues of mixed-mode oscillations. We also make explicit the connection between our results here with prior studies of torus canards and torus canard explosion in R3, and discuss how our methods can be extended to fast/slow systems of arbitrary (finite) dimension.

Banana regime pressure anisotropy in a bumpy cylinder magnetic field

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

Garcia-Perciante, A.L.; Callen, J.D.; Shaing, K.C.

The pressure anisotropy is calculated for a plasma in a bumpy cylindrical magnetic field in the low collisionality (banana) regime for small magnetic-field modulations ({epsilon}{identical_to}{delta}B/2B<<1). Solutions are obtained by integrating the drift-kinetic equation along field lines in steady state. A closure for the local value of the parallel viscous force B{center_dot}{nabla}{center_dot}{pi}{sub parallel} is then calculated and is shown to exceed the flux-surface-averaged parallel viscous force by a factor of O(1/{epsilon}). A high-frequency limit ({omega}>>{nu}) for the pressure anisotropy is also determined and the calculation is then extended to include the full frequency dependence by using an expansion inmore » Cordey eigenfunctions.« less

Reverberation Mapping the Dusty Torus in Active Galactic Nuclei: the Influence of Torus Geometry and Structure on the Measured Reverberation Radius

NASA Astrophysics Data System (ADS)

Almeyda, Triana

2018-01-01

The obscuring circumnuclear dusty torus is a cornerstone of AGN unification, yet its shape, composition, and structure have not been well constrained. Infrared (IR) interferometry can partially resolve the dust structures in nearby AGN. However, the size and structure of the torus can also be investigated at all redshifts by reverberation mapping, that is, analyzing the temporal variability of the torus dust emission in response to changes in the AGN luminosity. In simple models, the lag between the AGN optical continuum variations and the torus IR response is directly related to the effective size of the emitting region. However, the IR response is sensitive to many poorly constrained variables including the geometry and illumination of the torus, which complicates the interpretation of measured reverberation lags. I will present results from the first comprehensive analysis of the multi-wavelength IR torus response, showing how various structural and geometrical torus parameters influence the measured lag. A library of torus response functions has been computed using a new code, TORMAC, which simulates the temporal response of the IR emission of a 3D ensemble of dust clouds given an input optical light curve. TORMAC accounts for anisotropic emission from the dust clouds, inter-cloud and AGN-cloud shadowing, and anisotropic illumination of the torus by the AGN continuum source. We can use the model grid to quantify the relationship between the lag and the effective size of the torus for various torus parameters at any selected wavelength. Although the shapes of the response functions vary widely over our grid parameter range, the reverberation lag provides an estimate of the effective torus radius that is always within a factor of 2.5. TORMAC can also be used to model observed IR light curves; we present preliminary simulations for the “changing-look” Seyfert galaxy, NGC 6418, which exhibited large IR variability during a recent Spitzer monitoring campaign. This work will aid in the interpretation of reverberation mapping measurements, especially for the new VEILS wide field near-IR extragalactic time domain survey, whose aim is to use AGN IR reverberation mapping lags as cosmological standard candles.

Genetics Home Reference: laryngo-onycho-cutaneous syndrome

MedlinePlus

... This red, bumpy tissue is normally produced during wound healing and is usually replaced by skin cells as ... suggest that laminin 332 is also involved in wound healing. Additionally, researchers have proposed roles for laminin 332 ...

Research notes : geosynthetic materials in reflective crack prevention.

DOT National Transportation Integrated Search

2007-06-01

Extension of transverse cracks across roadway travel lanes is common in Oregon. Cracks form as a result of shrinkage and brittleness during very cold temperatures. These cracks deteriorate over time, spalling and creating bumpy riding surfaces. Prema...

Western Arabia Terra

NASA Image and Video Library

2002-12-19

This image from NASA Mars Odyssey covers a region in western Arabia Terra, which contains two interesting craters. The eastern floor of the largest crater seen in most of this image is bumpy and ridged in places and relatively smooth in regions.

Gravitational waves from extreme mass ratio inspirals around bumpy black holes

NASA Astrophysics Data System (ADS)

Moore, Christopher J.; Chua, Alvin J. K.; Gair, Jonathan R.

2017-10-01

The space based interferometer LISA will be capable of detecting the gravitational waves emitted by stellar mass black holes or neutron stars slowly inspiralling into the supermassive black holes found in the centre of most galaxies. The gravitational wave signal from such an extreme mass ratio inspiral (EMRI) event will provide a unique opportunity to test whether the spacetime metric around the central black hole is well described by the Kerr solution. In this paper a variant of the well studied ‘analytic kludge’ model for EMRIs around Kerr black holes is extended to a family of parametrically deformed bumpy black holes which preserve the basic symmetries of the Kerr metric. The new EMRI model is then used to quantify the constraints that LISA observations of EMRIs may be able to place on the deviations, or bumps, on the Kerr metric.

THE DIFFERENCES IN THE TORUS GEOMETRY BETWEEN HIDDEN AND NON-HIDDEN BROAD LINE ACTIVE GALACTIC NUCLEI

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

Ichikawa, Kohei; Ueda, Yoshihiro; Packham, Christopher

2015-04-20

We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any publishedmore » HBLR signature (NHBLR). Comparing the torus model parameters gives us the first quantitative torus geometrical view for each subgroup. We find that NHBLR AGNs have smaller torus opening angles and larger covering factors than HBLR AGNs. This suggests that the chance to observe scattered (polarized) flux from the BLR in NHBLR could be reduced by the dual effects of (a) less scattering medium due to the reduced scattering volume given the small torus opening angle and (b) the increased torus obscuration between the observer and the scattering region. These effects give a reasonable explanation for the lack of observed HBLR in some type-2 AGNs.« less

On Ramachandran angles, closed strings and knots in protein structure

NASA Astrophysics Data System (ADS)

Chen, Si; Niemi, Antti J.

2016-08-01

The Ramachandran angles (φ,\\psi ) of a protein backbone form the vertices of a piecewise geodesic curve on the surface of a torus. When the ends of the curve are connected to each other similarly, by a geodesic, the result is a closed string that in general wraps around the torus a number of times both in the meridional and the longitudinal directions. The two wrapping numbers are global characteristics of the protein structure. A statistical analysis of the wrapping numbers in terms of crystallographic x-ray structures in the protein data bank (PDB) reveals that proteins have no net chirality in the ϕ direction but in the ψ direction, proteins prefer to display chirality. A comparison between the wrapping numbers and the concept of folding index discloses a non-linearity in their relationship. Thus these three integer valued invariants can be used in tandem, to scrutinize and classify the global loop structure of individual PDB proteins, in terms of the overall fold topology.

Cooling Timescale of Dust Tori in Dying Active Galactic Nuclei

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

Ichikawa, Kohei; Tazaki, Ryo, E-mail: k.ichikawa@astro.columbia.edu

We estimate the dust torus cooling timescale once the active galactic nucleus (AGN) is quenched. In a clumpy torus system, once the incoming photons are suppressed, the cooling timescale of one clump from T {sub dust} = 1000 K to several 10 K is less than 10 years, indicating that the dust torus cooling time is mainly governed by the light crossing time of the torus from the central engine. After considering the light crossing time of the torus, the AGN torus emission at 12 μ m becomes over two orders of magnitude fainter within 100 years after the quenching.more » We also propose that those “dying” AGNs could be found using the AGN indicators with a different physical scale R such as 12 μ m band luminosity tracing AGN torus ( R ∼ 10 pc) and the optical [O iii] λ 5007 emission line tracing narrow line regions ( R = 10{sup 2–4} pc).« less

The Io plasma torus during the Cassini encounter with Jupiter: Temporal, radial and azimuthal variations

NASA Astrophysics Data System (ADS)

Steffl, Andrew Joseph

During the Cassini spacecraft's flyby of Jupiter (1 October 2000 to 31 March 2001), the Ultraviolet Imaging Spectrograph (UVIS) produced an extensive dataset consisting of several thousand spectrally-dispersed images of the lo plasma torus. The temporal, radial, and azimuthal variability of the to plasma torus during this period are examined. The total EUV power radiated from the torus is found to be ~1.7 x 10 12 W with variations of 25%. Several events were observed during which the torus brightened by 20% over a few hours. Significant changes in the composition of the torus plasma were observed between 1 October 2000 and 11 November 2000. The composition and electron temperature of the torus plasma as a function of radial distance were derived from a scale of the midnight sector of the torus. The radial profile during the Cassini epoch shows significant differences from the Voyager era. The Io torus is found to exhibit significant azimuthal variations in ion composition. This compositional variation is observed to have a period of 10.07 hours 1.5% longer than the System III rotation period of Jupiter. While exhibiting many similar characteristics, the periodicity in the UVIS data is 1.3% shorter than the "System IV" period. The amplitude of the azimuthal variation of S II and S IV varies between 5-25% during the observing period, while the amplitude of the variation of S III and O II remains in the range of 2-5%. The amplitude of the azimuthal compositional asymmetry appears to be modulated by its location in System III longitude. The observed temporal variability is reproduced by models of the torus chemistry that include a factor of 3 increase in the rate of oxygen and sulfur atoms supplied to the extended neutral clouds that are the source of the torus plasma coupled with a ~35% increase in the amount of riot electrons in the Io torus. The observed azimuthal variability of the Io torus is well matched by models incorporating a primary source of hot electrons that slips 12.2°/day relative to the System III coordinate system and a secondary source of hot electrons that remains fixed in System III.

Rocket FUV Observations of the Io Plasma Torus During the Shoemaker-Levy/9 Impacts

NASA Technical Reports Server (NTRS)

Stern, S. A.; Slater, D.; Cash, W.; Wilkinson, E.; Green, J.; Gladstone, R.

1995-01-01

We observed the Io torus from 820-1140 A on universal time (UT) 20.25 July 1994 from a sounding rocket telescope/spectrograph. These observations serve as only the fourth published spectrum of the torus in this wavelength range, and the only far ultraviolet (FUV) data documenting the state of the torus during the Shoemaker Levy 9 Impacts.

Traveling-wave device with mass flux suppression

DOEpatents

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

2000-01-01

A traveling-wave device is provided with the conventional moving pistons eliminated. Acoustic energy circulates in a direction through a fluid within a torus. A side branch may be connected to the torus for transferring acoustic energy into or out of the torus. A regenerator is located in the torus with a first heat exchanger located on a first side of the regenerator downstream of the regenerator relative to the direction of the circulating acoustic energy; and a second heat exchanger located on an upstream side of the regenerator. The improvement is a mass flux suppressor located in the torus to minimize time-averaged mass flux of the fluid. In one embodiment, the device further includes a thermal buffer column in the torus to thermally isolate the heat exchanger that is at the operating temperature of the device.

Observational Constraints on a Pluto Torus of Circumsolar Neutral Gas

NASA Astrophysics Data System (ADS)

Hill, M. E.; Kollmann, P.; McNutt, R. L., Jr.; Smith, H. T.; Bagenal, F.; Brown, L. E.; Elliott, H. A.; Haggerty, D. K.; Horanyi, M.; Krimigis, S. M.; Kusterer, M. B.; Lisse, C. M.; McComas, D. J.; Piquette, M. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Vandegriff, J. D.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, S. A.

2015-12-01

We present the concept of a neutral gas torus surrounding the Sun, aligned with Pluto's orbit, and place observational constraints based primarily on comparison of New Horizons (NH) measurements with a 3-D Monte Carlo model adapted from analogous satellite tori surrounding Saturn and Jupiter. Such a torus, or perhaps partial torus, should result from neutral N2 escaping from Pluto's exosphere. Unlike other more massive planets closer to the Sun, neutrals escape Pluto readily owing, e.g., to the high thermal speed relative to the escape velocity. Importantly, escaped neutrals have a long lifetime due to the great distance from the Sun, ~100 years for photoionization of N2 and ~180 years for photoionization of N, which results from disassociated N2. Despite the lengthy 248-year orbit, these long e-folding lifetimes may allow an enhanced neutral population to form an extended gas cloud that modifies the N2 spatial profile near Pluto. These neutrals are not directly observable by NH but once ionized N2+ or N+ are picked up by the solar wind, reaching ~50 keV, making these pickup ions (PUIs) detectable by NH's Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument. PEPSSI observations analyzed to date may constrain the N2 density; the remaining ~95% of the encounter data, scheduled for downlink in August along with similarly anticipated data from the Solar Wind Around Pluto (SWAP) experiment, should help determine the Pluto outgassing rates. Measurements from SWAP include the solar wind speed, a quantity that greatly enhances PUI studies by enabling us to directly account for the PUI distribution's sensitive dependence on plasma speed. Note that anomalous cosmic ray Si observed at Voyager is overabundant by a factor of ~3000 relative to interstellar composition. This might be related to "outer source" PUIs, but the fact that N2 and Si are indistinguishable in many instruments could mean that N2 is actually driving this apparent Si discrepancy.

7 CFR 51.759 - U.S. No. 3.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... colored; (4) Rough texture, not seriously bumpy; (5) Similar varietal characteristics; and, (6) Slightly...

Bifurcation structure of successive torus doubling

NASA Astrophysics Data System (ADS)

Sekikawa, Munehisa; Inaba, Naohiko; Yoshinaga, Tetsuya; Tsubouchi, Takashi

2006-01-01

The authors discuss the “embryology” of successive torus doubling via the bifurcation theory, and assert that the coupled map of a logistic map and a circle map has a structure capable of generating infinite number of torus doublings.

One-dimensional reduction of viscous jets. II. Applications

NASA Astrophysics Data System (ADS)

Pitrou, Cyril

2018-04-01

In a companion paper [Phys. Rev. E 97, 043115 (2018), 10.1103/PhysRevE.97.043115], a formalism allowing to describe viscous fibers as one-dimensional objects was developed. We apply it to the special case of a viscous fluid torus. This allows to highlight the differences with the basic viscous string model and with its viscous rod model extension. In particular, an elliptic deformation of the torus section appears because of surface tension effects, and this cannot be described by viscous string nor viscous rod models. Furthermore, we study the Rayleigh-Plateau instability for periodic deformations around the perfect torus, and we show that the instability is not sufficient to lead to the torus breakup in several droplets before it collapses to a single spherical drop. Conversely, a rotating torus is dynamically attracted toward a stationary solution, around which the instability can develop freely and split the torus in multiple droplets.

Modeling the Infrared Reverberation Response of the Circumnuclear Dusty Torus in AGNs: The Effects of Cloud Orientation and Anisotropic Illumination

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

Almeyda, Triana; Robinson, Andrew; Richmond, Michael

The obscuring circumnuclear torus of dusty molecular gas is one of the major components of active galactic nuclei (AGN). The torus can be studied by analyzing the time response of its infrared (IR) dust emission to variations in the AGN continuum luminosity, a technique known as reverberation mapping. The IR response is the convolution of the AGN ultraviolet/optical light curve with a transfer function that contains information about the size, geometry, and structure of the torus. Here, we describe a new computer model that simulates the reverberation response of a clumpy torus. Given an input optical light curve, the codemore » computes the emission of a 3D ensemble of dust clouds as a function of time at selected IR wavelengths, taking into account light travel delays. We present simulated dust emission responses at 3.6, 4.5, and 30 μ m that explore the effects of various geometrical and structural properties, dust cloud orientation, and anisotropy of the illuminating radiation field. We also briefly explore the effects of cloud shadowing (clouds are shielded from the AGN continuum source). Example synthetic light curves have also been generated, using the observed optical light curve of the Seyfert 1 galaxy NGC 6418 as input. The torus response is strongly wavelength-dependent, due to the gradient in cloud surface temperature within the torus, and because the cloud emission is strongly anisotropic at shorter wavelengths. Anisotropic illumination of the torus also significantly modifies the torus response, reducing the lag between the IR and optical variations.« less

Red in the Face: Understanding Rosacea

MedlinePlus

... sometimes-painful bumps. Inflamed eyes or eyelids. Swollen, red, bumpy nose, especially in men. Links Fast Facts about Rosacea Questions and Answers about Rosacea NIH Office of Communications and Public Liaison Building 31, Room 5B52 Bethesda, MD 20892-2094 nihnewsinhealth@od.nih. ...

Topological T-duality for torus bundles with monodromy

NASA Astrophysics Data System (ADS)

Baraglia, David

2015-05-01

We give a simplified definition of topological T-duality that applies to arbitrary torus bundles. The new definition does not involve Chern classes or spectral sequences, only gerbes and morphisms between them. All the familiar topological conditions for T-duals are shown to follow. We determine necessary and sufficient conditions for existence of a T-dual in the case of affine torus bundles. This is general enough to include all principal torus bundles as well as torus bundles with arbitrary monodromy representations. We show that isomorphisms in twisted cohomology, twisted K-theory and of Courant algebroids persist in this general setting. We also give an example where twisted K-theory groups can be computed by iterating T-duality.

Resonant torus-assisted tunneling.

PubMed

Yi, Chang-Hwan; Yu, Hyeon-Hye; Kim, Chil-Min

2016-01-01

We report a new type of dynamical tunneling, which is mediated by a resonant torus, i.e., a nonisolated periodic orbit. To elucidate the phenomenon, we take an open elliptic cavity and show that a pair of resonances localized on two classically disconnected tori tunnel through a resonant torus when they interact with each other. This so-called resonant torus-assisted tunneling is verified by using Husimi functions, corresponding actions, Husimi function distributions, and the standard deviations of the actions.

ECRH and its effects on neoclassical transport in a stellarator

NASA Astrophysics Data System (ADS)

Seol, Jaechun

The banana center orbit deviates significantly from the magnetic surface due to the symmetry-breaking term in the magnetic field configuration. Energetic electrons can escape the plasma without collision, since the drift speed is proportional to the perpendicular energy of electron and the collision frequency is reduced as the electron energy goes up. A direct loss flux can be generated from energetic electron population in a stellarator. Thus energetic electron populations can substantially modify the neoclassical transport properties in stellarators. A model accounting for this change in transport is developed assuming the presence of electron cyclotron resonance heating (ECRH). The quasilinear diffusion coefficient for second harmonic X-mode ECRH is developed for a bumpy stellarator. Care is taken in accounting for the pitch-angle dependence of the quasilinear diffusion coefficient since application to experiments with narrow resonance zones is of interest. Weakly relativistic effects are considered through the mass effect on the cyclotron frequency. For trapped particles in a three dimensional configuration, collisionless loss zones exist in velocity space. Radio-frequency (rf) waves accelerate trapped electrons into the direct loss zone in bumpy stellarators and produce a direct loss flux. An analytic expression for this loss flux is derived; it is proportional to the rf field strength and the value of the zeroth order distribution function at the minimum speed for collisionless loss. The direct loss flux of electrons is another source of a non-ambipolar particle flux in bumpy stellarators. This additional non-ambipolar flux modifies the ambipolarity equation which generally has multiple roots for the radial electric field. An electron root (large positive Er) is easily obtained if the electrons are in the 1/nu regime and the ions are in the nu regime.

HIAD Advancements and Extension of Mission Applications

NASA Technical Reports Server (NTRS)

Johnson, R. Keith; Cheatwood, F. McNeil; Calomino, Anthony M.; Hughes, Stephen J.; Korzun, Ashley M.; DiNonno, John M.; Lindell, Mike C.; Swanson, Greg T.

2016-01-01

The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology has made significant advancements over the last decade with flight test demonstrations and ground development campaigns. The first generation (Gen-1) design and materials were flight tested with the successful third Inflatable Reentry Vehicle Experiment flight test of a 3-m HIAD (IRVE-3). Ground development efforts incorporated materials with higher thermal capabilities for the inflatable structure (IS) and flexible thermal protection system (F-TPS) as a second generation (Gen-2) system. Current efforts and plans are focused on extending capabilities to improve overall system performance and reduce areal weight, as well as expand mission applicability. F-TPS materials that offer greater thermal resistance, and ability to be packed to greater density, for a given thickness are being tested to demonstrated thermal performance benefits and manufacturability at flight-relevant scale. IS materials and construction methods are being investigated to reduce mass, increase load capacities, and improve durability for packing. Previous HIAD systems focused on symmetric geometries using stacked torus construction. Flight simulations and trajectory analysis show that symmetrical HIADs may provide L/D up to 0.25 via movable center of gravity (CG) offsets. HIAD capabilities can be greatly expanded to suit a broader range of mission applications with asymmetric shapes and/or modulating L/D. Various HIAD concepts are being developed to provide greater control to improve landing accuracy and reduce dependency upon propulsion systems during descent and landing. Concepts being studied include a canted stack torus design, control surfaces, and morphing configurations that allow the shape to be actively manipulated for flight control. This paper provides a summary of recent HIAD development activities, and plans for future HIAD developments including advanced materials, improved construction techniques, and alternate geometry concepts that will greatly expand HIAD mission applications.

The Emission and Distribution of Dust of the Torus of NGC 1068

NASA Astrophysics Data System (ADS)

Lopez-Rodriguez, Enrique; Fuller, Lindsay; Alonso-Herrero, Almudena; Efstathiou, Andreas; Ichikawa, Kohei; Levenson, Nancy A.; Packham, Chris; Radomski, James; Ramos Almeida, Cristina; Benford, Dominic J.; Berthoud, Marc; Hamilton, Ryan; Harper, Doyal; Kovávcs, Attila; Santos, Fabio P.; Staguhn, J.; Herter, Terry

2018-06-01

We present observations of NGC 1068 covering the 19.7–53.0 μm wavelength range using FORCAST and HAWC+ on board SOFIA. Using these observations, high-angular-resolution infrared (IR) and submillimeter observations, we find an observational turnover of the torus emission in the 30–40 μm wavelength range with a characteristic temperature of 70–100 K. This component is clearly different from the diffuse extended emission in the narrow line and star formation regions at 10–100 μm within the central 700 pc. We compute 2.2–432 μm 2D images using the best inferred CLUMPY torus model based on several nuclear spectral energy distribution (SED) coverages. We find that when 1–20 μm SED is used, the inferred result gives a small torus size (<4 pc radius) and a steep radial dust distribution. The computed torus using the 1–432 μm SED provides comparable torus sizes, {5.1}-0.4+0.4 pc radius, and morphology to the recently resolved 432 μm Atacama Large Millimeter Array observations. This result indicates that the 1–20 μm wavelength range is not able to probe the full extent of the torus. The characterization of the turnover emission of the torus using the 30–60 μm wavelength range is sensitive to the detection of cold dust in the torus. The morphology of the dust emission in our 2D image at 432 μm is spatially coincident with the cloud distribution, while the morphology of the emission in the 1–20 μm wavelength range shows an elongated morphology perpendicular to the cloud distribution. We find that our 2D CLUMPY torus image at 12 μm can produce comparable results to those observed using IR interferometry.

Using a 2D Model of the Io Plasma Torus to Investigate the Effects of Density Variations on the Morphology and Intensity of the Io Footprint

NASA Astrophysics Data System (ADS)

Payan, A. P.; Rajendar, A.; Paty, C. S.; Bonfond, B.; Crary, F.

2012-12-01

Io is the primary source of plasma in the Jovian magnetosphere, continuously releasing approximately 1 ton/s of SO2 from volcanic eruptions. The interaction of Io with Jupiter's magnetosphere is strongly influenced by the density structure of the resulting plasma torus and the position of Io relative to the center of the torus [Bonfond et al. 2008]. This unusual interaction produces a complex auroral feature on Jupiter's ionosphere known as the Io footprint. Hubble Space Telescope (HST) observations of Jupiter's far-UV aurora during spring 2007 showed an increased number of isolated auroral blobs along with a continuous expansion of Jupiter's main auroral oval over a few months. These blobs were associated with several large injections of hot plasma between 9 and 27 Jovian radii. These events coincided with a large volcanic eruption of the Tvashtar Paterae on Io, as observed by the New Horizons spacecraft [Spencer et al., 2007]. This, in turn, may have resulted in a significant increase in the plasma torus density. Besides, on June 7th, 2007, the Io footprint momentarily became so faint that it disappeared under a diffuse patch of emission remaining from an injection blob [Bonfond et al., 2012]. The goal of the present study is to examine the relationship between the increased density of the plasma torus and the dimming of the Io footprint. We implement a 2D model of the Io plasma torus that treats the variable-density torus as being composed of discrete layers of uniform density. As the co-rotating plasma in the plasma torus impinges on Io, Alfvén waves are launched at a pushback angle obtained from Gurnett and Goertz [1981]. The waves propagate inside the plasma torus through reflection and refraction at density discontinuities where they lose some of their initial energy. Using the above model, we can track the Alfvén wave fronts in the plasma torus and determine the longitude at which they exit the torus along with the corresponding remaining energy. Since Alfvén waves are capable of accelerating charged particles along magnetic field lines, we assume that the discrete Io footprint features are created at these longitudes, and that the intensity of each of these features is positively correlated to the energy transported by the wave front as it exits the plasma torus. Therefore, the model allows us to investigate both the effects of density changes and of Io's position in the plasma torus on the intensity and the morphology of the Io footprint. In this context, the model enables us to determine the density increase in the plasma torus required to explain the apparent disappearance of Io footprint given its position at that time.

Io: IUE observations of its atmosphere and the plasma torus

NASA Technical Reports Server (NTRS)

Ballester, G. E.; Moos, H. W.; Feldman, P. D.; Strobel, D. F.; Skinner, T. E.; Bertaux, J.-L.; Festou, M. C.

1988-01-01

Two of the main components of the atmosphere of Io, neutral oxygen and sulfur, were detected with the IUE. Four observations yield brightnesses that are similar, regardless of whether the upstream or the downstream sides of the torus plasma flow around Io is observed. A simple model requires the emissions to be produced by the interaction of O and S columns in the exospheric range with 2 eV electrons. Cooling of the 5 eV torus electrons is required prior to their interaction with the atmosphere of Io. Inconsistencies in the characteristics of the spectra that cannot be accounted for in this model require further analysis with improved atomic data. The Io plasma torus was monitored with the IUE. The long-term stability of the warm torus is established. The observed brightnesses were analyzed using a model of the torus, and variations of less than 30 percent in the composition are observed, the quantitative results being model dependent.

Ion Temperature Control of the Io Plasma Torus

NASA Technical Reports Server (NTRS)

Delamere, P. A.; Schneider, N. M.; Steffl, A. J.; Robbins, S. J.

2005-01-01

We report on observational and theoretical studies of ion temperature in the Io plasma torus. Ion temperature is a critical factor for two reasons. First, ions are a major supplier of energy to the torus electrons which power the intense EUV emissions. Second, ion temperature determines the vertical extent of plasma along field lines. Higher temperatures spread plasma out, lowers the density and slows reaction rates. The combined effects can play a controlling role in torus energetics and chemistry. An unexpected tool for the study of ion temperature is the longitudinal structure in the plasma torus which often manifests itself as periodic brightness variations. Opposite sides of the torus (especially magnetic longitudes 20 and 200 degrees) have been observed on numerous occasions to have dramatically different brightness, density, composition, ionization state, electron temperature and ion temperature. These asymmetries must ultimately be driven by different energy flows on the opposite sides, presenting an opportunity to observe key torus processes operating under different conditions. The most comprehensive dataset for the study of longitudinal variations was obtained by the Cassini UVIS instrument during its Jupiter flyby. Steffl (Ph.D. thesis, 2005) identified longitudinal variations in all the quantities listed above wit the exception of ion temperature. We extend his work by undertaking the first search for such variation in the UVIS dataset. We also report on a 'square centimeter' model of the torus which extend the traditional 'cubic centimeter' models by including the controlling effects of ion temperature more completely.

D-He-3 spherical torus fusion reactor system study

NASA Astrophysics Data System (ADS)

Macon, William A., Jr.

1992-04-01

This system study extrapolates present physics knowledge and technology to predict the anticipated characteristics of D-He3 spherical torus fusion reactors and their sensitivity to uncertainties in important parameters. Reference cases for steady-state 1000 MWe reactors operating in H-mode in both the 1st stability regime and the 2nd stability regime were developed and assessed quantitatively. These devices would a very small aspect ratio (A=1,2), a major radius of about 2.0 m, an on-axis magnetic field less than 2 T, a large plasma current (80-120 MA) dominated by the bootstrap effect, and high plasma beta (greater than O.6). The estimated cost of electricity is in the range of 60-90 mills/kW-hr, assuming the use of a direct energy conversion system. The inherent safety and environmental advantages of D-He3 fusion indicate that this reactor concept could be competitive with advanced fission breeder reactors and large-scale solar electric plants by the end of the 21st century if research and development can produce the anticipated physics and technology advances.

View from 30,000 Feet

ERIC Educational Resources Information Center

Freifeld, Lorri

2012-01-01

Orchestrating a smooth training transition during a merger or acquisition is never easy. When Delta Air Lines absorbed Northwest Airlines Corp. in 2008, the Training function realized it was in for a bumpy ride. This article looks at the strategies used and progress made since the takeover was announced.

Torus elements used in effective shock absorber

NASA Technical Reports Server (NTRS)

Cunningham, P.; Platus, D. L.

1966-01-01

Energy absorbing device forces torus elements to revolve annularly between two concentric tubes when a load is applied to one tube. Interference forces can be varied by using torus elements of different thicknesses. The device operates repeatedly in compression or tension, and under problems of large onset rate tolerance or structural overload.

Feasibility of Juno radio occultations of the Io plasma torus

NASA Astrophysics Data System (ADS)

Phipps, P. H.; Withers, P.

2016-12-01

Jupiter's magnetosphere is driven by internally produced plasma. The innermost Galilean satellite, Io, isthe dominant source of this plasma. Volcanoes on Io's surface create an atmosphere of sulfur and oxygenwhich escapes into Jupiter's magnetosphere and becomes ionized. This ionized material is trapped byJupiter's magnetic field and creates a torus of plasma centered at Io's orbital radius, called the Io plasmatorus. This torus is divided into three regions distinct in both density and composition. Densities in thistorus can be probed by spacecraft via radio occultations. A radio occultation occurs when plasma comesbetween a spacecraft and a receiver during a time when the spacecraft is sending a radio signal. The Junospacecraft, which arrived in orbit around Jupiter in July 2016, is in an orbit which will be ideal forperforming radio occultations of the Io plasma torus. We test the feasibility of using thetelecommunications system on the Juno spacecraft to perform a radio occultation. Io plasma torusdensities derived from Voyager 1 data are used in creating a model torus. Using the Ka and X-band radiofrequencies we derive vertical profiles for the total electron content of the modeled Io plasma torus. AMarkov Chain Monte Carlo fit is performed on the derived profiles to extract, for each of the torusregions, the scale height and peak total electron content. The scale height can be used to derive atemperature for the torus while the peak total electron content can be used to derive the peak electrondensity. We show that Juno radio occultation measurements of the Io plasma torus are feasible andscientifically valuable.

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

NASA Astrophysics Data System (ADS)

Smith, Nathan; Ginsburg, Adam; Bally, John

2018-03-01

We present Atacama Large Millimeter Array (ALMA) observations of 12CO 2-1 emission from circumstellar material around the massive star Eta Carinae (η Car). These observations reveal new structural details about the cool equatorial torus located ˜4000 au from the star. The CO torus is not a complete azimuthal loop, but rather, is missing its near side, which appears to have been cleared away. The missing material matches the direction of apastron in the eccentric binary system, making it likely that η Car's companion played an important role in disrupting portions of the torus soon after ejection. Molecular gas seen in ALMA data aligns well with the cool dust around η Car previously observed in mid-infrared (IR) maps, whereas hot dust resides at the inner surface of the molecular torus. The CO also coincides with the spatial and velocity structure of near-IR H2 emission. Together, these suggest that the CO torus seen by ALMA is actually the pinched waist of the Homunculus polar lobes, which glows brightly because it is close to the star and warmer than the poles. The near side of the torus appears to be a blowout, associated with fragmented equatorial ejecta. We discuss implications for the origin of various features north-west of the star. CO emission from the main torus implies a total gas mass in the range of 0.2-1 M⊙ (possibly up to 5 M⊙ or more, although with questionable assumptions). Deeper observations are needed to constrain CO emission from the cool polar lobes.

75 FR 78758 - Prohibited Transaction Exemptions From Certain Prohibited Transaction Restrictions

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-16

..., between the DB Torus Japan Master Portfolio (the Master Fund), in which the assets of a client employee...) Prior to investing in DB Torus Japan Fund Ltd. (hereinafter the Feeder Fund, the vehicle through which... DB Torus Japan Fund Ltd. (hereinafter the Feeder Fund, the vehicle through which investments in the...

Success and failure of the plasma analogy for Laughlin states on a torus

NASA Astrophysics Data System (ADS)

Fremling, Mikael

2017-01-01

We investigate the nature of the plasma analogy for the Laughlin wave function on a torus describing the quantum Hall plateau at ν =\\frac{1}{q} . We first establish, as expected, that the plasma is screening if there are no short nontrivial paths around the torus. We also find that when one of the handles has a short circumference—i.e. the thin-torus limit—the plasma no longer screens. To quantify this we compute the normalization of the Laughlin state, both numerically and analytically. In the thin torus limit, the analytical form of the normalization simplify and we can reconstruct the normalization and analytically extend it back into the 2D regime. We find that there are geometry dependent corrections to the normalization, and this in turn implies that the plasma in the plasma analogy is not screening when in the thin torus limit. Despite the breaking of the plasma analogy in this limit, the analytical approximation is still a good description of the normalization for all tori, and also allows us to compute hall viscosity at intermediate thickness.

Long Term Monitoring of the Io Plasma Torus During the Galileo Encounter

NASA Technical Reports Server (NTRS)

Brown, Michael E.

2002-01-01

In the fall of 1999, the Galileo spacecraft made four passes into the Io plasma torus, obtaining the best in situ measurements ever of the particle and field environment in this densest region of the Jovian magnetosphere. Supporting observations from the ground are vital for understanding the global and temporal context of the in situ observations. We conducted a three-month-long Io plasma torus monitoring campaign centered on the time of the Galileo plasma torus passes to support this aspect of the Galileo mission. The almost-daily plasma density and temperature measurements obtained from our campaign allow the much more sparse but also much more detailed Galileo data to be used to address the issues of the structure of the Io plasma torus, the stability mechanism of the Jovian magnetosphere, the transport of material from the source region near Io, and the nature and source of persistent longitudinal variations. Combining the ground-based monitoring data with the detailed in situ data offers the only possibility for answering some of the most fundamental questions about the nature of the Io plasma torus.

A pictorial study of an invariant torus in phase space of four dimensions.

NASA Technical Reports Server (NTRS)

Baxter, R.; Eiserike, H.; Stokes, A.

1972-01-01

An investigation was conducted with the aid of a computer graphics device at Goddard Space Flight Center to study the behavior of the invariant manifolds of a particular fourth-order equation, as a parameter in the equation is varied over the interval from 0 to 1. The equation consists of two coupled Van der Pol equations. For a small parameter value, the manifold is an asymptotically stable torus, where the flow on the torus is simply a rotation. As the value of the parameter is increased, the only thing that changes is the nature of the flow on the torus, which itself persists throughout the parameter variation. It is shown that ultimately the four periodic cycles which appear play a more significant part in the phase profile of the system than does the torus itself.

Analytical model for the density distribution in the Io plasma torus

NASA Technical Reports Server (NTRS)

Mei, YI; Thorne, Richard M.; Bagenal, Fran

1995-01-01

An analytical model is developed for the diffusive equilibrium plasma density distribution in the Io plasma torus. The model has been employed successfully to follow the ray path of plasma waves in the multi-ion Jovian magnetosphere; it would also be valuable for other studies of the Io torus that require a smooth and continuous description of the plasma density and its gradients. Validity of the analytical treatment requires that the temperature of thermal electrons be much lower than the ion temperature and that superthermal electrons be much less abundant than the thermal electrons; these two conditions are satisfied in the warm outer region of the Io torus from L = 6 to L = 10. The analytical solutions agree well with exact numerical calculations for the most dense portion of the Io torus within 30 deg of the equator.

Infrared emission in Seyfert 2 galaxies - Reprocessed radiation from a dusty torus?

NASA Technical Reports Server (NTRS)

Storchi-Bergmann, Thaisa; Mulchaey, John S.; Wilson, Andrew S.

1992-01-01

New and existing data for a sample of nine Seyfert 2 galaxies with known 'ionization cones' are combined in order to test whether collimation results from shadowing of radiation from a small isotropic nuclear source by a thick dusty torus. The number of ionizing photons emitted by the compact nucleus is calculated from the emission-line ratios measured for gas within the cones. On the assumption that this compact nuclear source radiates isotropically, the optical-UV power incident on the torus, which is expected to be reradiated in the IR, is determined. It is found that the observed IRAS luminosities are consistent with the torus model in eight of the nine objects with sufficient data to perform the calculation. It is concluded that the data are generally consistent with collimation and reradiation by a dusty torus.

On the Existence of Star Products on Quotient Spaces of Linear Hamiltonian Torus Actions

NASA Astrophysics Data System (ADS)

Herbig, Hans-Christian; Iyengar, Srikanth B.; Pflaum, Markus J.

2009-08-01

We discuss BFV deformation quantization (Bordemann et al. in A homological approach to singular reduction in deformation quantization, singularity theory, pp. 443-461. World Scientific, Hackensack, 2007) in the special case of a linear Hamiltonian torus action. In particular, we show that the Koszul complex on the moment map of an effective linear Hamiltonian torus action is acyclic. We rephrase the nonpositivity condition of Arms and Gotay (Adv Math 79(1):43-103, 1990) for linear Hamiltonian torus actions. It follows that reduced spaces of such actions admit continuous star products.

Analysis of 2D Torus and Hub Topologies of 100Mb/s Ethernet for the Whitney Commodity Computing Testbed

NASA Technical Reports Server (NTRS)

Pedretti, Kevin T.; Fineberg, Samuel A.; Kutler, Paul (Technical Monitor)

1997-01-01

A variety of different network technologies and topologies are currently being evaluated as part of the Whitney Project. This paper reports on the implementation and performance of a Fast Ethernet network configured in a 4x4 2D torus topology in a testbed cluster of 'commodity' Pentium Pro PCs. Several benchmarks were used for performance evaluation: an MPI point to point message passing benchmark, an MPI collective communication benchmark, and the NAS Parallel Benchmarks version 2.2 (NPB2). Our results show that for point to point communication on an unloaded network, the hub and 1 hop routes on the torus have about the same bandwidth and latency. However, the bandwidth decreases and the latency increases on the torus for each additional route hop. Collective communication benchmarks show that the torus provides roughly four times more aggregate bandwidth and eight times faster MPI barrier synchronizations than a hub based network for 16 processor systems. Finally, the SOAPBOX benchmarks, which simulate real-world CFD applications, generally demonstrated substantially better performance on the torus than on the hub. In the few cases the hub was faster, the difference was negligible. In total, our experimental results lead to the conclusion that for Fast Ethernet networks, the torus topology has better performance and scales better than a hub based network.

Juno Radio Science Observations and Gravity Science Calibrations of Plasma Electron Content in Io Plasma Torus

NASA Astrophysics Data System (ADS)

Yang, Y. M.; Buccino, D.; Folkner, W. M.; Oudrhiri, K.; Phipps, P. H.; Parisi, M.; Kahan, D. S.

2017-12-01

Interplanetary and Earth ionosphere plasma electrons can have significant impacts on radio frequency signal propagation such as telecommunication between spacecraft and the Deep Space Network (DSN). On 27 August 2016, the first closest approach of The Juno spacecraft (Perijove 1) provided an opportunity to observe plasma electrons inside of the Io plasma torus using radio science measurements from Juno. Here, we report on the derivations of plasma electron content in the Io plasma torus by using two-way coherent radio science measurements made from Juno's Gravity Science Instrument and the Deep Space Network. During Perijove 1, Juno spacecraft passed through the inner region (perijove altitude of 1.06 Jovian Radii) between Jupiter and the Io plasma torus. Significant plasma electron variations of up to 30 TEC units were observed while the radio link between Juno and the DSN traveled through the Io plasma torus. In this research, we compare observations made by open-loop and closed-loop processes using different frequency radio signals, corresponding Io plasma torus model simulations, and other Earth ionosphere observations. The results of three-dimensional Io plasma model simulations are consistent with observations with some discrepancies. Results are shown to improve our understanding of the Io plasma torus effect on Juno gravity science measurements and its calibrations to reduce the corresponding (non-gravity field induced) radio frequency shift.

Certain approximation problems for functions on the infinite-dimensional torus: Lipschitz spaces

NASA Astrophysics Data System (ADS)

Platonov, S. S.

2018-02-01

We consider some questions about the approximation of functions on the infinite-dimensional torus by trigonometric polynomials. Our main results are analogues of the direct and inverse theorems in the classical theory of approximation of periodic functions and a description of the Lipschitz spaces on the infinite-dimensional torus in terms of the best approximation.

Influence of self-gravity on the runaway instability of black-hole-torus systems.

PubMed

Montero, Pedro J; Font, José A; Shibata, Masaru

2010-05-14

Results from the first fully general relativistic numerical simulations in axisymmetry of a system formed by a black hole surrounded by a self-gravitating torus in equilibrium are presented, aiming to assess the influence of the torus self-gravity on the onset of the runaway instability. We consider several models with varying torus-to-black-hole mass ratio and angular momentum distribution orbiting in equilibrium around a nonrotating black hole. The tori are perturbed to induce the mass transfer towards the black hole. Our numerical simulations show that all models exhibit a persistent phase of axisymmetric oscillations around their equilibria for several dynamical time scales without the appearance of the runaway instability, indicating that the self-gravity of the torus does not play a critical role favoring the onset of the instability, at least during the first few dynamical time scales.

Observations of the Io plasma torus

NASA Technical Reports Server (NTRS)

Lane, A. L.; Moos, H. W.; Clarke, J. T.; Atreya, S. K.

1981-01-01

The short wavelength spectrography on the IUE satellite was used to obtain spectra of the plasma torus near the orbit of Io about Jupiter. Three exposures of about 8 hours each taken in March and May 1979 show emission features due to SII, SIII, and OIII. The absence of features at other wavelengths permits upper limits to be other species in the torus.

Combinatorial quantisation of the Euclidean torus universe

NASA Astrophysics Data System (ADS)

Meusburger, C.; Noui, K.

2010-12-01

We quantise the Euclidean torus universe via a combinatorial quantisation formalism based on its formulation as a Chern-Simons gauge theory and on the representation theory of the Drinfel'd double DSU(2). The resulting quantum algebra of observables is given by two commuting copies of the Heisenberg algebra, and the associated Hilbert space can be identified with the space of square integrable functions on the torus. We show that this Hilbert space carries a unitary representation of the modular group and discuss the role of modular invariance in the theory. We derive the classical limit of the theory and relate the quantum observables to the geometry of the torus universe.

A total and polarized infrared flux view of the AGN clumpy torus

NASA Astrophysics Data System (ADS)

Lopez Rodriguez, Enrique

2013-12-01

Magnetohydrodynamical theories consider the torus of Active Galactic Nuclei (AGN) to be part of an outflow wind moving away from the central engine. In this framework, the torus is a particular region of the wind, where dusty and optically thick clouds are formed. The outflows are strongly related to the accretion rate and magnetic field strength, which play an important role in the creation, morphology and evolution of the torus. Through infrared (IR) imaging and polarimetry observations, this dissertation (1) searches for signatures of dusty tori in low-luminosity AGN (LLAGN); (2) explores the role and strength of magnetic field in the torus; and (3) investigates the nucleus of radio-loud AGN. Recent theoretical models predicted that LLAGN do not host a Seyfert-like torus, since low-luminosities (<1042 erg s-1 ) cannot sustain the required outflow rate. High-spatial resolution mid-IR (MIR) imaging and nuclear spectral energy distribution of 22 LLAGN reveals different IR characteristics by dividing the sample in terms of the Eddington ratio. These galaxies show a diversity of nuclear morphologies and have a high MIR/X-ray luminosity ratio compared to higher-luminosity AGN. Star formation, jets and/or truncated accretion disk can explain the MIR excess. Although several models have been made to account for the outflowing dusty winds from the central engine, the magnetic field strength at the position of the torus remains poorly characterized. Through a novel study using near-IR polarimetry, the magnetic field strength in the clumpy torus was estimated. Specifically, if paramagnetic alignment is assumed in the dusty clouds of the torus, the magnetic field strength of the torus of IC5063 is estimated to be in the range of 12--128 mG. Alternatively, Chandrasekhar-Fermi method suggests a lower-limit magnetic field strength of 13 mG. For the archetypical radio-loud AGN, Cygnus A, MIR polarimetry using CanariCam on the 10.4-m Gran Telescopio de Canarias revealed a high polarized, 11+/-3% and 12+/-3% (at Si2 and Si5 respectively) unresolved nucleus. Polarimetric modeling suggests that the MIR polarization arises from a synchrotron component. This result represents the most compelling MIR polarization detection of synchrotron radiation in Cygnus A.

Computerized Method for the Generation of Molecular Transmittance Functions in the Infrared Region.

DTIC Science & Technology

1979-12-31

exponent of the double exponential function were ’bumpy’ for some cases. Since the nature of the transmittance does not predict this behavior, we...T ,IS RECOMPUTED FOR THE ORIGIONAL DATA *USING THE PIECEWISE- ANALITICAL TRANSMISSION FUNCTION.’//20X, *’STANDARD DEVIATIONS BETWEEN THE ACTUAL TAU

Beyond Public Spending

ERIC Educational Resources Information Center

Corney, Mark

2009-01-01

Britain is in the longest recession since the Second World War. Mass unemployment is back. The road to recovery could be long and bumpy. On the fiscal front, the deficit could be higher than the 175 billion British Pounds forecast for 2009-10. Bringing the deficit under control will require higher taxes and lower public spending. In an effort to…

Structurally colored films with superhydrophobicity and wide viewing angles based on bumpy melanin-like particles

NASA Astrophysics Data System (ADS)

Yi, Bo; Shen, Huifang

2018-01-01

Non-iridescent structural colors and lotus effect universally existing in the nature provide a great inspiration for artificially developing angle-independent and high hydrophobic structurally colored films. To this end, a facile strategy is put forward for achieving superhydrophobic structurally colored films with wide viewing angles and high visibility based on bumpy melanin-like polydopamine-coated polystyrene particles. Here, hierarchical and amorphous structures are assembled in a self-driven manner due to particles' protrusive surfaces. The superhydrophobicity of the structurally colored films, with water contact angle up to 151°, is realized by combining the hierarchical surface roughness with a dip-coating process of polydimethylsiloxane-hexane solution, while angle-independence revealed in the films is ascribed to amorphous arrays. In addition, benefited from an essential light-absorbing property and high refractive index of polydopamine, the visibility of as-prepared colored films is fundamentally enhanced. Moreover, the mechanical robustness of the films is considerably boosted by inletting 3-aminopropyltriethoxysilane. This fabrication strategy might provide an opportunity for promoting the open-air application of structurally colored coatings.

Investigating the dusty torus of Seyfert galaxies using SOFIA/FORCAST photometry

NASA Astrophysics Data System (ADS)

Fuller, Lindsay; Lopez-Rodriguez, Enrique; Packham, Christopher C.; Ramos-Almeida, Cristina; Alonso-Herrero, Almudena; Levenson, Nancy; Radomski, James; Ichikawa, Kohei; Garcia-Bernete, Ismael; Gonzalez-Martin, Omaira; Diaz Santos, Tanio; Martinez-Paredes, Mariela

2017-06-01

We present 31.5 μm imaging photometry of 11 nearby Seyfert galaxies observed from the Stratospheric Observatory For Infrared Astronomy (SOFIA) using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). We tentatively detect extended 31 μm emission for the first time in our sample. In combination with this new data set, subarcsecond resolution 1-18 μm imaging and 7.5-13 μm spectroscopic observations were used to compute the nuclear spectral energy distribution (SED) of each galaxy. We found that the turnover of the torus emission does not occur at wavelengths ≤31.5 μm, which we interpret as a lower-limit for the wavelength of peak emission. We used Clumpy torus models to fit the nuclear infrared (IR) SED and infer trends in the physical parameters of the AGN torus for the galaxies in the sample. Including the 31.5 μm nuclear flux in the SED 1) reduces the number of clumpy torus models compatible with the data, and 2) modifies the model output for the outer radial extent of the torus for 10 of the 11 objects. Specifically, six (60%) objects show a decrease in radial extent while four (40%) show an increase. We find torus outer radii ranging from <1pc to 8.4 pc. We also present new 37.1 μm imaging data for 4 of the 11 Seyfert galaxies, as well as 3 additional Seyferts.

On the Disappearance of a Cold Molecular Torus around the Low-luminosity Active Galactic Nucleus of NGC 1097

NASA Astrophysics Data System (ADS)

Izumi, T.; Kohno, K.; Fathi, K.; Hatziminaoglou, E.; Davies, R. I.; Martín, S.; Matsushita, S.; Schinnerer, E.; Espada, D.; Aalto, S.; Onishi, K.; Turner, J. L.; Imanishi, M.; Nakanishi, K.; Meier, D. S.; Wada, K.; Kawakatu, N.; Nakajima, T.

2017-08-01

We used the Atacama Large Millimeter/Submillimeter Array to map the CO(3-2) and the underlying continuum emissions around the type-1 low-luminosity active galactic nucleus (LLAGN; bolometric luminosity ≲ {10}42 erg s-1) of NGC 1097 at ˜10 pc resolution. These observations revealed a detailed cold gas distribution within a ˜100 pc of this LLAGN. In contrast to the luminous Seyfert galaxy NGC 1068, where a ˜7 pc cold molecular torus was recently revealed, a distinctively dense and compact torus is missing in our CO(3-2) integrated intensity map of NGC 1097. Based on the CO(3-2) flux, the gas mass of the torus of NGC 1097 would be a factor of ≳2-3 less than that found for NGC 1068 by using the same CO-to-H2 conversion factor, which implies less active nuclear star formation and/or inflows in NGC 1097. Our dynamical modeling of the CO(3-2) velocity field implies that the cold molecular gas is concentrated in a thin layer as compared to the hot gas traced by the 2.12 μm H2 emission in and around the torus. Furthermore, we suggest that NGC 1097 hosts a geometrically thinner torus than NGC 1068. Although the physical origin of the torus thickness remains unclear, our observations support a theoretical prediction that geometrically thick tori with high opacity will become deficient as AGNs evolve from luminous Seyferts to LLAGNs.

Departure from corotation of the Io plasma torus - Local plasma production

NASA Technical Reports Server (NTRS)

Pontius, D. H., Jr.; Hill, T. W.

1982-01-01

The departure of the Jovian magnetosphere from rigid corotation is adequately explained by outward plasma transport at distances where L is greater than approximately 10. The departure of 5% observed in the Io plasma torus, however, is too large to be accounted for simply by plasma transport. Local plasma production is proposed as the main factor determining the corotation lag in the torus. The outward pick-up current provided by ionization of neutral atoms is calculated and related to the current produced in the ionosphere by the corotation lag. This leads to an expression giving the corotation lag of the torus as a function of radial distance. Charge transfer is found to be an important process, allowing the majority of the torus mass to be ejected from the magnetosphere in a neutral state. Thus, the mass loading rate is found to be several times that inferred from examination of the corotation lag associated with outward plasma transport.

A time-dependent anisotropic plasma chemistry model of the Io plasma torus

NASA Astrophysics Data System (ADS)

Arridge, C. S.

2016-12-01

The physics of the Io plasma torus is typically modelled using one box neutral-plasma chemistry models, often referred to as neutral cloud theory models (e.g., Barbosa 1994; Delamere and Bagenal 2003). These models incorporate electron impact and photoionisation, charge exchange, molecular dissociation/recombination reactions, atomic radiatiative losses and Coulomb collisional heating. Isotropic Maxwellian distributions are usually assumed in the implementation of these models. Observationally a population of suprathermal electrons has been identified in the plasma torus and theoretically they have been shown to be important in reproducing the observed ionisation balance in the torus (e.g., Barbosa 1994). In this paper we describe an anisotropic plasma chemistry model for the Io torus that is inspired by ion cyclotron wave observations (Huddleston et al. 1994; Leisner et al. 2011), ion anisotropies due to pick up (Wilson et al. 2008), and theoretical ideas on the maintenance of the suprathermal electron population (Barbosa 1994). We present both steady state calculations and also time varying solutions (e.g., Delamere et al. 2004) where increases in the neutral source rate in the torus generates perturbations in ion anisotropies that subsequently decay over a timescale much longer than the duration of the initial perturbation. We also present a method for incorporating uncertainties in reaction rates into the model.

Infrared Spectral Energy Distribution Decomposition of WISE-selected, Hyperluminous Hot Dust-obscured Galaxies

NASA Astrophysics Data System (ADS)

Fan, Lulu; Han, Yunkun; Nikutta, Robert; Drouart, Guillaume; Knudsen, Kirsten K.

2016-06-01

We utilize a Bayesian approach to fit the observed mid-IR-to-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous hot dust-obscured galaxies (Hot DOGs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot DOGs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot DOGs into torus and cold dust components. The main results are as follows. (1) Hot DOGs in our submillimeter-detected sample are hyperluminous ({L}{IR}≥slant {10}13{L}⊙ ), with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average ˜ 24% of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot DOGs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at ˜ 10{--}50 μ {{m}}, suggesting that the heating sources of Hot DOGs should be buried AGNs. (3) Hot DOGs have high dust temperatures ({T}{dust}˜ 72 K) and high IR luminosity of cold dust. The {T}{dust}{--}{L}{IR} relation of Hot DOGs suggests that the increase in IR luminosity for Hot DOGs is mostly due to the increase of the dust temperature, rather than dust mass. Hot DOGs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot DOGs can be expected by their relatively high dust temperatures. (4) Hot DOGs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot DOGs by employing a physical model of galaxy evolution. This result suggests that Hot DOGs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolutions of massive galaxies, transforming them from the dusty starburst-dominated phase to the optically bright QSO phase.

A Bumpy Road: Principal as Technology Leader

ERIC Educational Resources Information Center

Gosmire, Doreen; Grady, Marilyn L.

2007-01-01

Technology expenditures and usage in schools have risen by nearly 300 percent during the last three decades. Few principals claim to be technology experts, but most aspire to design a map that leads their schools to success with educational technology. The key to success on the journey is not to know everything, but to ask the right questions.…

A Bumpy Journey to Culturally Relevant Pedagogy in an Urban Middle School: Are We There Yet?

ERIC Educational Resources Information Center

Rozansky, Carol Lloyd

2010-01-01

Culturally relevant pedagogy (CRP) offers the promise of increased success for underserved students in urban schools. This qualitative case study examines a middle school reading teacher's understandings and implementation of CRP and the researcher's supportive role over a three-semester collaboration. Two categories of results are described:…

Digital Advances Reshaping K-12 Testing. Technology Counts, 2014. Education Week. Volume 33 Number 25

ERIC Educational Resources Information Center

Edwards, Virginia B., Ed.

2014-01-01

Figuring out how to use digital tools to transform testing requires a willingness to invest in new technologies and the patience to experiment with novel approaches, a commitment to ongoing professional development and reliable technical support, and an openness to learn from mistakes. Whatever bumpy ride this technological journey takes, experts…

A case of long QT syndrome: challenges on a bumpy road.

PubMed

Magnusson, Peter; Gustafsson, Per-Erik

2017-06-01

Beta-agonist treatment during pregnancy may unmask the diagnosis of long QT syndrome. The QT prolongation can result in functional AV block. A history of seizure and/or sudden death in a family member should raise suspicion of ventricular tachycardia. More than one mutation may coexist. Refusal of beta-blocker therapy complicates risk stratification.

Harvard Education Letter. Volume 23, Number 3, May-June 2007

ERIC Educational Resources Information Center

Chauncey, Caroline, Ed.

2007-01-01

"Harvard Education Letter" is published bimonthly by the Harvard Graduate School of Education. This issue of "Harvard Education Letter" contains the following articles: (1) The Road to School Improvement: It's Hard, It's Bumpy, and It Takes as Long as It Takes (Richard F. Elmore and Elizabeth A. City); (2) Better Teaching with Web Tools: How…

Bumpy Path into a Profession: What California's Beginning Teachers Experience. Policy Brief 14-2

ERIC Educational Resources Information Center

Koppich, Julia E.; Humphrey, Daniel C.

2014-01-01

In California as elsewhere, state policy anticipates that aspiring teachers will follow a uniform, multistep path into the profession. It assumes they will complete a preparation program and earn a preliminary credential, take a teaching job and be assigned probationary status, complete a two-year induction program (the Beginning Teacher Support…

On the energy crisis in the Io plasma torus

NASA Technical Reports Server (NTRS)

Smith, Robert A.; Bagenal, Fran; Cheng, Andrew F.; Strobel, Darrell

1988-01-01

Recent calculations of the energy balance of the Io plasma torus show that the observed UV and EUV radiation cannot be maintained solely via energy input by the ion pickup mechanism. Current theoretical models of the torus must be modified to include non-local energy input. It is argued that the required energy may be supplied by inward diffusion of energetic heavy ions with energies less than about 20 keV.

Dynamics and formation of obscuring tori in AGNs

NASA Astrophysics Data System (ADS)

Bannikova, Elena Yu.; Sergeyev, Alexey V.

2017-12-01

We considered the evolution of a self-gravitating clumpy torus in the gravitational field of the central mass of an active galactic nucleus (AGN) in the framework of the N-body problem. The initial conditions take into account winds with different opening angles. Results of our N-body simulations show that the clouds moving on orbits with a spread in inclinations and eccentricities form a toroidal region. This mechanism can solve the problem of the geometrical thickness of the torus. The velocity of the clouds at the inner edge of the torus is lower than in a disk model that can explain the observed rotation curves. We discuss the scenario of torus formation related with the beginning of the AGN stage.

BRST symmetry for a torus knot

NASA Astrophysics Data System (ADS)

Pandey, Vipul Kumar; Prasad Mandal, Bhabani

2017-08-01

We develop BRST symmetry for the first time for a particle on the surface of a torus knot by analyzing the constraints of the system. The theory contains 2nd-class constraints and has been extended by introducing the Wess-Zumino term to convert it into a theory with first-class constraints. BFV analysis of the extended theory is performed to construct BRST/anti-BRST symmetries for the particle on a torus knot. The nilpotent BRST/anti-BRST charges which generate such symmetries are constructed explicitly. The states annihilated by these nilpotent charges consist of the physical Hilbert space. We indicate how various effective theories on the surface of the torus knot are related through the generalized version of the BRST transformation with finite-field-dependent parameters.

Construction of 3D Metallic Nanowire Arrays on Arbitrarily-Shaped Substrate.

NASA Astrophysics Data System (ADS)

Chen, Fei; Li, Jingning; Yu, Fangfang; Peng, Ru-Wen; Wang, Mu; Mu Wang Team

Formation of three-dimensional (3D) nanostructures is an important step of advanced manufacture for new concept devices with novel functionality. Despite of great achievements in fabricating nanostructures with state of the art lithography approaches, these nanostructures are normally limited on flat substrates. Up to now it remains challenging to build metallic nanostructures directly on a rough and bumpy surface. Here we demonstrate a unique approach to fabricate metallic nanowire arrays on an arbitrarily-shaped surface by electrodeposition, which is unknown before 2016. Counterintuitively here the growth direction of the nanowires is perpendicular to their longitudinal axis, and the specific geometry of nanowires can be achieved by introducing specially designed shaped substrate. The spatial separation and the width of the nanowires can be tuned by voltage, electrolyte concentration and temperature in electrodeposition. By taking cobalt nanowire array as an example, we demonstrate that head-to-head and tail-to-tail magnetic domain walls can be easily introduced and modulated in the nanowire arrays, which is enlightening to construct new devices such as domain wall racetrack memory. We acknowledge the foundation from MOST and NSF(China).

Radiolysis aspects of the aqueous self-cooled blanket concept and the problem of tritium extraction

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

Bruggeman, A.; Snykers, M.; DeRegge, P.

1988-09-01

In the Aqueous Self-Cooled Blanket (ASCB) concept, an aqueous /sup 6/Li solution in a metallic structure is used as a fusion reactor shielding-breeding blanket. Radiolysis effects could be very important for the design and the use of an ASCB. Although many aspects of the radiation chemistry of water and dilute aqueous solutions are now reasonably well understood, it is not possible to predict the radiochemical behaviour of the concentrated candidate ASCB solutions quantitatively. However, by means of a worst case calculation for a possible ASCB for the Next European Torus (NET) it is shown that even with an important ratemore » of water decomposition the ASCB concept is still workable. Gas bubbles and explosive mixtures can be avoided by increasing the pressure in the neutron irradiated zone and by extracting and/or recombining the radiolytically produced hydrogen and oxygen. This could require an additional inert gas loop, which could also be used as part of the tritium extraction installation.« less

Dusty Donuts: Modeling the Reverberation Response of the Circumnuclear Dusty Torus Emission in AGN

NASA Astrophysics Data System (ADS)

Almeyda, Triana R.

The obscuring circumnuclear torus of dusty molecular gas is one of the major components of AGN (active galactic nuclei), yet its size, composition, and structure are not well understood. These properties can be studied by analyzing the temporal variations of the infrared (IR) dust emission from the torus in response to variations in the AGN continuum luminosity; a technique known as reverberation mapping. In a recent international campaign 12 AGN were monitored using the Spitzer Space Telescope and several ground-based telescopes, providing a unique set of well-sampled mid-IR and optical light curves which are required in order to determine the approximate sizes of the tori in these AGN. To help extract structural information contained in the data a computer model, TORMAC, has been developed that simulates the reverberation response of the clumpy torus emission. Given an input optical light curve, the code computes the emission of a 3D ensemble of dust clouds as a function of time at selected IR wavelengths, taking into account light travel delays. A large library of torus reverberation response simulations has been constructed, to investigate the effects of various geometrical and structural properties such as inclination, cloud distribution, disk half-opening angle, and radial depth. The effects of dust cloud orientation, cloud optical depth, anisotropy of the illuminating AGN radiation field, dust cloud shadowing, and cloud occultation are also explored in detail. TORMAC was also used to generate synthetic IR light curves for the Seyfert 1 galaxy, NGC 6418, using the observed optical light curve as the input, to investigate how the torus and dust cloud properties incorporated in the code affect the results obtained from reverberation mapping. This dissertation presents the most comprehensive investigation to date showing that radiative transfer effects within the torus and anisotropic illumination of the torus can strongly influence the torus IR response at different wavelengths, and should be accounted for when interpreting reverberation mapping data. TORMAC provides a powerful modeling tool that can generate simulated IR light curves for direct comparison to observations. As many types of astronomical sources are both variable and embedded in, or surrounded, by dust, TORMAC also has applications for dust reverberation studies well beyond the AGN observed in the Spitzer monitoring campaign.

Magnetic fields in the torus of AGN and Mid-IR polarimetry of Cygnus A

NASA Astrophysics Data System (ADS)

Lopez-Rodriguez, E.; Packham, C.; Young, S.; Elitzur, M.; Levenson, N. A.; Mason, R. E.; Ramos Almeida, C.; Alonso-Herrero, A.; Jones, T. J.; Perlman, E.

2012-12-01

An optically and geometrically thick torus obscures the central engine of Active Galactic Nuclei (AGN) from some lines of sight. From a magnetohydrodynamical framework, the torus can be considered to be a particular region of clouds surrounding the central engine where the clouds are dusty and optically thick. In this framework, the magnetic field plays an important role in the creation, morphology and evolution of the torus. If the dust grains within the clouds are assumed to be aligned by paramagnetic alignment, then the ratio of the intrinsic polarisation and visual extinction, P(%)/Av, is a function of the magnetic field strength. To estimate the visual extinction through the torus and constrain the polarisation mechanisms in the nucleus of AGN, we developed a polarisation model to fit both the total and polarised flux in a 1.2" (˜ 263 pc) aperture of the type 2 AGN, IC5063. We consider the physical conditions and environment of the gas and dust for the torus of IC5063. Then, through paramagnetic alignment, we estimate a magnetic field strength in the range of 12 - 128 mG in the NIR emitting regions of the torus of IC5063. Alternatively, we estimate the magnetic field strength in the plane of the sky using the Chandrasekhar-Fermi method. The minimum magnetic field strength in the plane of the sky is estimated to be 13 and 41 mG depending of the conditions within the torus of IC5063. These techniques afford the chance to make a survey of AGN, to investigate the effects of magnetic field strength on the torus, accretion, and interaction to the host galaxy. We present Si2 [8.7 um] and Si5 [11.6 um] imaging polarimetry of Cygnus A using CanariCam on the 10.4-m Gran Telescopio de Canarias (GTC). Preliminary polarimetric results show a highly polarized nucleus with 11±3% and 12±3% in a 0.5" (˜500pc) aperture in Si2 and Si5, respectively. The PA of polarization remains constant, 32±8 deg, in both filters. In order to disentangle the origin of the polarized component in the nucleus of Cygnus A, further modeling using several polarizing mechanisms e.g. synchrotron, dichroic absorption/emission and/or scattering will be performed.

Near-infrared polarimetric adaptive optics observations of NGC 1068: a torus created by a hydromagnetic outflow wind

NASA Astrophysics Data System (ADS)

Lopez-Rodriguez, E.; Packham, C.; Jones, T. J.; Nikutta, R.; McMaster, L.; Mason, R. E.; Elvis, M.; Shenoy, D.; Alonso-Herrero, A.; Ramírez, E.; González Martín, O.; Hönig, S. F.; Levenson, N. A.; Ramos Almeida, C.; Perlman, E.

2015-09-01

We present J' and K' imaging linear polarimetric adaptive optics observations of NGC 1068 using MMT-Pol on the 6.5-m MMT. These observations allow us to study the torus from a magnetohydrodynamical (MHD) framework. In a 0.5 arcsec (30 pc) aperture at K', we find that polarization arising from the passage of radiation from the inner edge of the torus through magnetically aligned dust grains in the clumps is the dominant polarization mechanism, with an intrinsic polarization of 7.0 ± 2.2 per cent. This result yields a torus magnetic field strength in the range of 4-82 mG through paramagnetic alignment, and 139^{+11}_{-20} mG through the Chandrasekhar-Fermi method. The measured position angle (P.A.) of polarization at K' is found to be similar to the P.A. of the obscuring dusty component at few parsec scales using infrared interferometric techniques. We show that the constant component of the magnetic field is responsible for the alignment of the dust grains, and aligned with the torus axis on to the plane of the sky. Adopting this magnetic field configuration and the physical conditions of the clumps in the MHD outflow wind model, we estimate a mass outflow rate ≤0.17 M⊙ yr-1 at 0.4 pc from the central engine for those clumps showing near-infrared dichroism. The models used were able to create the torus in a time-scale of ≥105 yr with a rotational velocity of ≤1228 km s-1 at 0.4 pc. We conclude that the evolution, morphology and kinematics of the torus in NGC 1068 can be explained within a MHD framework.

Connecting Io's volcanic activity to the Io plasma torus: comparison of Galileo/NIMS volcanic and ground-based torus observations

NASA Astrophysics Data System (ADS)

Magalhaes, F. P.; Lopes, R. M. C.; Rathbun, J. A.; Gonzalez, W. D.; Morgenthaler, J. P.; Echer, E.; Echer, M. P. D. S.

2015-12-01

Io, the innermost of the Jupiter's four Galilean moons, is a remarkable object in the Solar System, due to its intense and energetic volcanic activity. The volcanic sulfur and oxygen in Io's tenuous atmosphere escapes forming an extended neutral cloud around Io and Jupiter. Subsequently, by ionization and pickup ions, a ring of charged particles encircling Jupiter is created, forming the Io plasma torus. Considering this scenario, it is reasonable to expect that the Io plasma torus should be affected by changes in Io's volcanism. Interactions between Io and the Jovian environment is unique and yet not very well understood. Here we present two sets of observations. One from the Galileo Near-Infrared Imaging Spectrograph (NIMS) instrument, which obtained spectral image cubes between 0.7 and 5.2 microns. The other dataset is from ground-based observations of the [SII] 6731 Å emission lines from the Io plasma torus, obtained at McMath-Pierce Solar Telescope, at Kitt Peak. Our dataset from the [SII] 6731 Å emission lines cover more years than the one from the NIMS data. The years presented in this work for a comparative study are from 1998 through 2001. Using the NIMS instrument we were able to identify which volcanoes were active and measure their level of activity. From the [SII] 6731 Å emission lines we were able to trace the densest part of the torus and also the brightness of both ansa. By comparing the results from the Galileo instrument and the ground-based observations, we are exploring how the Io plasma torus responds to large eruptions from Io. We aim with this study to help improve our understanding of this complex coupled system, Jupiter-Io.

PINCHED PLASMA REACTOR

DOEpatents

Phillips, J.A.; Suydam, R.; Tuck, J.L.

1961-07-01

BS>A plasma confining and heating reactor is described which has the form of a torus with a B/sub 2/ producing winding on the outside of the torus and a helical winding of insulated overlapping tunns on the inside of the torus. The inner helical winding performs the double function of shielding the plasma from the vitreous container and generating a second B/sub z/ field in the opposite direction to the first B/sub z/ field after the pinch is established.

Induction effects of torus knots and unknots

NASA Astrophysics Data System (ADS)

Oberti, Chiara; Ricca, Renzo L.

2017-09-01

Geometric and topological aspects associated with induction effects of field lines in the shape of torus knots/unknots are examined and discussed in detail. Knots are assumed to lie on a mathematical torus of circular cross-section and are parametrized by standard equations. The induced field is computed by direct integration of the Biot-Savart law. Field line patterns of the induced field are obtained and several properties are examined for a large family of knots/unknots up to 51 crossings. The intensity of the induced field at the origin of the reference system (center of the torus) is found to depend linearly on the number of toroidal coils and reaches maximum values near the boundary of the mathematical torus. New analytical estimates and bounds on energy and helicity are established in terms of winding number and minimum crossing number. These results find useful applications in several contexts when the source field is either vorticity, electric current or magnetic field, from vortex dynamics to astrophysics and plasma physics, where highly braided magnetic fields and currents are present.

Multi-layer accretion disks around black holes and formation of a hot ion-torus

NASA Astrophysics Data System (ADS)

Hujeirat, A.; Camenzind, M.

2000-08-01

We present the first 2D steady-state numerical radiative hydrodynamical calculations showing the formation of a low-density hot torus in the very inner region of accretion disks around a black hole. The inner part of the disk is found to be thermally unstable when Bremsstrahlung is the dominant cooling mechanism. Within the parameter regime used and in the absence of magnetic fields, the torus-plasma is highly time-dependent with supersonic oscillating motion with respect to the electron temperature. When the soft photons from the disk comptonize the electrons efficiently, the ion-pressure supported torus shrinks in volume, but decelerates further the inward motion into the hole. We speculate that magnetic fields would stabilize the tori by lowering its energy package through initiating jets and/or outflows. In the outer region, we find that the scale height of the angular velocity HΩ largely exceeds the scale height of the density Hρ. This yields a multi-layer flow-structure in the vertical direction which slows the inwards motion into the BH significantly, enhancing further the formation of the hot torus.

Torus palatinus and torus mandibularis in edentulous patients.

PubMed

Al Quran, Firas A M; Al-Dwairi, Ziad N

2006-05-01

To determine the prevalence of tori in Jordanian edentulous patients, the sex variation in their distribution, and their clinical characteristics. Three hundred and thirty eight patients were examined in the Prosthodontic Clinic in the Department of Restorative Dentistry at Jordan University of Science and Technology. The location, extent, and clinical presentation of tori were recorded related to the age and sex of patients. The overall prevalence of tori was 13.9%. The prevalence of torus palatinus was 29.8% (14/47), while that of torus mandibularis was significantly higher 42.6% (20/47). Both types of tori were associated with each other in 27.7% of cases (13/47). There was no significant difference in the prevalence of tori between males and females. There seems to be a strong association between mandibular and palatal tori.

Designing torus-doubling solutions to discrete time systems by hybrid projective synchronization

NASA Astrophysics Data System (ADS)

Xie, Hui; Wen, Guilin

2013-11-01

Doubling of torus occurs in high dimensional nonlinear systems, which is related to a certain kind of typical second bifurcations. It is a nontrivial task to create a torus-doubling solution with desired dynamical properties based on the classical bifurcation theories. In this paper, dead-beat hybrid projective synchronization is employed to build a novel method for designing stable torus-doubling solutions into discrete time systems with proper properties to achieve the purpose of utilizing bifurcation solutions as well as avoiding the possible conflict of physical meaning of the created solution. Although anti-controls of bifurcation and chaos synchronizations are two different topics in nonlinear dynamics and control, the results imply that it is possible to develop some new interdisciplinary methods between chaos synchronization and anti-controls of bifurcations.

Coping with Hearing Loss and High School

ERIC Educational Resources Information Center

Exceptional Parent, 2010

2010-01-01

High school can be a bumpy road for teenagers, especially since most teenagers are trying to fit in and start to define their own individuality and future. Now imagine if a teenager has hearing loss. Besides not being able to hear their instructors or friends as well as their classmates, self image problems can be magnified if they need to wear…

Actually the World Is Quite Bumpy: Using Friedman in the International Business Law Classroom

ERIC Educational Resources Information Center

Dhooge, Lucien J.

2006-01-01

In "The World Is Flat: A Brief History of the Twenty-First Century," Pulitzer Prize recipient and New York Times foreign affairs correspondent Thomas L. Friedman examines the evolution of globalization in the six years since the publication of his highly acclaimed introduction to the topic in "The Lexus and the Olive Tree: Understanding…

The Legitimacy of Curriculum Development in Post-Colonial Hong Kong: Insights from the Case of Liberal Studies

ERIC Educational Resources Information Center

Fung, Dennis; Liang, Tim

2018-01-01

Liberal Studies was initially introduced as a non-statutory subject in Hong Kong in 1992. It then confronted intense opposition and a bumpy implementation path before securing mandatory status in the new senior secondary curriculum introduced in 2009. Recently, this core subject has been under review. Whilst it is considered to promote students'…

Magnetic Fluctuations in the Jovian Magnetosphere

NASA Technical Reports Server (NTRS)

Russell, Christopher T.

2002-01-01

The engine that drives the jovian magnetosphere is the mass added to the Io ion torus, accelerated to corotational velocities by field-aligned currents that couple the Io torus to the jovian ionosphere. The mass of the torus builds up to an amount that the magnetic forces cannot contain and the plasma, first slowly and then more rapidly, drifts outward. Numerous authors have treated this problem based first on the observations of the Pioneer 10 and 11 flybys; then on Voyager 1 and 2, and Ulysses; and finally most recently the Galileo orbiter. The initial observations revealed the now familiar magnetodisk, in which the field above and below the magnetic equator became quite radial in orientation and much less dipolar. The Galileo observations show this transformation to occur on average at 24 R(sub J) and to often be quite abrupt. These observations are consistent with outward transport of magnetized plasma that moves ever faster radially until about 50 R(sub J) on the nightside where the field lines stretch to the breaking point, reconnection occurs, and plasma and field islands are transported down the tail ultimately removing the mass from the magnetosphere that Io had deposited deep in the inner torus. The reconnection process creates empty flux tubes connected to Jupiter that are buoyant and thought to float inward and replace the flux carried out with the torus plasma. As described above, the jovian magnetosphere could very well be in a state of steady laminar circulation, but indeed it is not. The process is very unsteady and the wave levels can be very intense. The existence of these waves in turn can lead to processes that compete with the radial circulation pattern in removing plasma from the system. These waves can scatter particles so that they precipitate into the ionosphere. This process should be important in the Io torus where the atmospheric loss cone is relatively large and becomes less important as the loss cone decreases in size with radial distance. However, the Io torus is relatively quiet compared to the region outside the torus and it is not obvious without studying this scattering carefully whether the loss in the torus or out of the torus is greater and whether it can act rapidly enough to compete with the radial transport of ions to the tail in the life cycle of the mass added at Io. Closer to Io the ion cyclotron waves are most intense and possibly are associated with the losses in the Io flux tube. The waves are also diagnostic of both the Io atmospheric composition and the size and strength of the massloading process.

Hand aperture patterns in prehension.

PubMed

Bongers, Raoul M; Zaal, Frank T J M; Jeannerod, Marc

2012-06-01

Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7cm in diameter) were placed at 30, 60, 90, or 120cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping. Copyright © 2011 Elsevier B.V. All rights reserved.

Torus as phase space: Weyl quantization, dequantization, and Wigner formalism

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

Ligabò, Marilena, E-mail: marilena.ligabo@uniba.it

2016-08-15

The Weyl quantization of classical observables on the torus (as phase space) without regularity assumptions is explicitly computed. The equivalence class of symbols yielding the same Weyl operator is characterized. The Heisenberg equation for the dynamics of general quantum observables is written through the Moyal brackets on the torus and the support of the Wigner transform is characterized. Finally, a dequantization procedure is introduced that applies, for instance, to the Pauli matrices. As a result we obtain the corresponding classical symbols.

Studies for the Europagenic Plasma Source in Jupiter's Inner Magnetosphere during the Galileo Europa Mission

NASA Technical Reports Server (NTRS)

Smyth, William H.

2004-01-01

Progress in research to understand the three-dimensional nature of the Europagenic plasma torus is summarized. Efforts to improve the plasma torus description near Europa's orbit have included a better understanding of Europa's orbit and an improved description of the planetary magnetic field. New plasma torus chemistry for molecular and atomic species has been introduced and implemented in Europa neutral cloud models. Preliminary three-dimensional model calculations for Europa's neutral clouds and their plasma sources are presented.

Parsec-Scale Obscuring Accretion Disk with Large-Scale Magnetic Field in AGNs

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.

2017-01-01

A magnetic field dragged from the galactic disk, along with inflowing gas, can provide vertical support to the geometrically and optically thick pc (parsec) -scale torus in AGNs (Active Galactic Nuclei). Using the Soloviev solution initially developed for Tokamaks, we derive an analytical model for a rotating torus that is supported and confined by a magnetic field. We further perform three-dimensional magneto-hydrodynamic simulations of X-ray irradiated, pc-scale, magnetized tori. We follow the time evolution and compare models that adopt initial conditions derived from our analytic model with simulations in which the initial magnetic flux is entirely contained within the gas torus. Numerical simulations demonstrate that the initial conditions based on the analytic solution produce a longer-lived torus that produces obscuration that is generally consistent with observed constraints.

Outer satellite atmospheres: Their extended nature and planetary interactions. [sodium cloud of Io, hydrogen torus of Titan, and comet atmospheres

NASA Technical Reports Server (NTRS)

Smyth, W. H.

1980-01-01

Highly developed numerical models are applied to interpret extended-atmosphere data for the sodium cloud of Io and the hydrogen torus of Titan. Solar radiation pressure was identified and verified by model calculations as the mechanism to explain two different east-west asymmetries observed in the sodium cloud. Analysis of sodium line profile data, suggesting that a Jupiter magnetospheric wind may be responsible for high speed sodium atoms emitted from Io, and preliminary modeling of the interaction of the Io plasma torus and Io's sodium cloud are also reported. Models presented for Titan's hydrogen torus are consistent both with the recent Pioneer 11 measurements and earlier Earth-orbiting observations by the Copernicus satellite. Progress is reported on developing models for extended gas and dust atmospheres of comets.

Turbulent equipartition pinch of toroidal momentum in spherical torus

NASA Astrophysics Data System (ADS)

Hahm, T. S.; Lee, J.; Wang, W. X.; Diamond, P. H.; Choi, G. J.; Na, D. H.; Na, Y. S.; Chung, K. J.; Hwang, Y. S.

2014-12-01

We present a new analytic expression for turbulent equipartition (TEP) pinch of toroidal angular momentum originating from magnetic field inhomogeneity of spherical torus (ST) plasmas. Starting from a conservative modern nonlinear gyrokinetic equation (Hahm et al 1988 Phys. Fluids 31 2670), we derive an expression for pinch to momentum diffusivity ratio without using a usual tokamak approximation of B ∝ 1/R which has been previously employed for TEP momentum pinch derivation in tokamaks (Hahm et al 2007 Phys. Plasmas 14 072302). Our new formula is evaluated for model equilibria of National Spherical Torus eXperiment (NSTX) (Ono et al 2001 Nucl. Fusion 41 1435) and Versatile Experiment Spherical Torus (VEST) (Chung et al 2013 Plasma Sci. Technol. 15 244) plasmas. Our result predicts stronger inward pinch for both cases, as compared to the prediction based on the tokamak formula.

Parsec-scale Obscuring Accretion Disk with Large-scale Magnetic Field in AGNs

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

Dorodnitsyn, A.; Kallman, T.

A magnetic field dragged from the galactic disk, along with inflowing gas, can provide vertical support to the geometrically and optically thick pc-scale torus in AGNs. Using the Soloviev solution initially developed for Tokamaks, we derive an analytical model for a rotating torus that is supported and confined by a magnetic field. We further perform three-dimensional magneto-hydrodynamic simulations of X-ray irradiated, pc-scale, magnetized tori. We follow the time evolution and compare models that adopt initial conditions derived from our analytic model with simulations in which the initial magnetic flux is entirely contained within the gas torus. Numerical simulations demonstrate thatmore » the initial conditions based on the analytic solution produce a longer-lived torus that produces obscuration that is generally consistent with observed constraints.« less

Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field

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

Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com

2016-11-15

Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torusmore » knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.« less

NuSTAR Observations of Water Megamaser AGN

NASA Technical Reports Server (NTRS)

Masini, A.; Comastri, A.; Balokvic, M.; Zaw, I.; Puccetti, S.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Zhang, William W.

2016-01-01

Aims. We study the connection between the masing disk and obscuring torus in Seyfert 2 galaxies. Methods. We present a uniform X-ray spectral analysis of the high energy properties of 14 nearby megamaser active galactic nuclei observed by NuSTAR. We use a simple analytical model to localize the maser disk and understand its connection with the torus by combining NuSTAR spectral parameters with the available physical quantities from VLBI mapping.Results. Most of the sources that we analyzed are heavily obscured, showing a column density in excess of approx.10(exp 23) cm(exp -2); in particular, 79% are Compton-thick [NH is greater than 1.5 x 10(exp 24) cm(exp -2)]. When using column densities measured by NuSTAR with the assumption that the torus is the extension of the maser disk, and further assuming a reasonable density profile, we can predict the torus dimensions. They are found to be consistent with mid-IR interferometry parsec-scale observations of Circinus and NGC 1068. In this picture, the maser disk is intimately connected to the inner part of the torus. It is probably made of a large number of molecular clouds that connect the torus and the outer part of the accretion disk, giving rise to a thin disk rotating in most cases in Keplerian or sub-Keplerian motion. This toy model explains the established close connection between water megamaser emission and nuclear obscuration as a geometric effect.

Jet-torus connection in radio galaxies. Relativistic hydrodynamics and synthetic emission

NASA Astrophysics Data System (ADS)

Fromm, C. M.; Perucho, M.; Porth, O.; Younsi, Z.; Ros, E.; Mizuno, Y.; Zensus, J. A.; Rezzolla, L.

2018-01-01

Context. High resolution very long baseline interferometry observations of active galactic nuclei have revealed asymmetric structures in the jets of radio galaxies. These asymmetric structures may be due to internal asymmetries in the jets or they may be induced by the different conditions in the surrounding ambient medium, including the obscuring torus, or a combination of the two. Aims: In this paper we investigate the influence of the ambient medium, including the obscuring torus, on the observed properties of jets from radio galaxies. Methods: We performed special-relativistic hydrodynamic (SRHD) simulations of over-pressured and pressure-matched jets using the special-relativistic hydrodynamics code Ratpenat, which is based on a second-order accurate finite-volume method and an approximate Riemann solver. Using a newly developed radiative transfer code to compute the electromagnetic radiation, we modelled several jets embedded in various ambient medium and torus configurations and subsequently computed the non-thermal emission produced by the jet and thermal absorption from the torus. To better compare the emission simulations with observations we produced synthetic radio maps, taking into account the properties of the observatory. Results: The detailed analysis of our simulations shows that the observed properties such as core shift could be used to distinguish between over-pressured and pressure matched jets. In addition to the properties of the jets, insights into the extent and density of the obscuring torus can be obtained from analyses of the single-dish spectrum and spectral index maps.

Radiative cooling efficiencies and predicted spectra of species of the Io plasma torus

NASA Technical Reports Server (NTRS)

Shemansky, D. E.

1980-01-01

Calculations of the physical condition of the Io plasma torus have been made based on the recent Voyager EUV observations. The calculations represent an assumed thin plasma collisional ionization equilibrium among the states within each species. The observations of the torus are all consistent with this condition. The major energy loss mechanism is radiative cooling in discrete transitions. Calculations of radiative cooling efficiencies of the identified species leads to an estimated energy loss rate of at least 1.5 x 10 to the 12th watts. The mean electron temperature and density of the plasma are estimated to be 100,000 K and 2100/cu cm. The estimated number densities of S III, S IV, and O III are roughly 95, 80, and 190-740/cu cm. Upper limits have been placed on a number of other species based on the first published Voyager EUV spectrum of the torus. The assumption that energy is supplied to the torus through injection of neutral particles from Io leads to the conclusion that ion loss rates are controlled by diffusion, and relative species abundances consequently are not controlled by collisional ionization equilibrium.

Convection in Neptune's magnetosphere

NASA Technical Reports Server (NTRS)

Hill, T. W.; Dessler, A. J.

1990-01-01

It is assumed that nonthermal escape from Triton's atmosphere produces a co-orbiting torus of unionized gas (presumably nitrogen and hydrogen) that subsequently becomes ionized by electron impact to populate a partial Triton plasma torus analogous to the Io plasma torus in Jupiter's magnetosphere. Centrifugal and magnetic-mirror forces confine the ions to a plasma sheet located between the magnetic and centrifugal equators. The ionization rate, and hence the torus ion concentration, is strongly peaked at the two points (approximately 180 deg apart in longitude) at which Triton's orbit intersects the plasma equator. During the course of Neptune's rotation these intersection points trace out two arcs roughly 75 deg in longitudinal extent, which we take to be the configuration of the resulting (partial) plasma torus. The implied partial ring currents produce a quadrupolar (four-cell) convection system that provides rapid outward transport of plasma from the arcs. Ring-current shielding, however, prevents this convection system from penetrating very far inside the plasma-arc distance. It is suggested that this convection/shielding process accounts for the radial confinement of trapped particles (150 keV or greater) within L = 14.3 as observed by the Voyager LECP instrument.

TRANSP-based Trajectory Optimization of the Current Profile Evolution to Facilitate Robust Non-inductive Ramp-up in NSTX-U

NASA Astrophysics Data System (ADS)

Wehner, William; Schuster, Eugenio; Poli, Francesca

2016-10-01

Initial progress towards the design of non-inductive current ramp-up scenarios in the National Spherical Torus Experiment Upgrade (NSTX-U) has been made through the use of TRANSP predictive simulations. The strategy involves, first, ramping the plasma current with high harmonic fast waves (HHFW) to about 400 kA, and then further ramping to 900 kA with neutral beam injection (NBI). However, the early ramping of neutral beams and application of HHFW leads to an undesirably peaked current profile making the plasma unstable to ballooning modes. We present an optimization-based control approach to improve on the non-inductive ramp-up strategy. We combine the TRANSP code with an optimization algorithm based on sequential quadratic programming to search for time evolutions of the NBI powers, the HHFW powers, and the line averaged density that define an open-loop actuator strategy that maximizes the non-inductive current while satisfying constraints associated with the current profile evolution for MHD stable plasmas. This technique has the potential of playing a critical role in achieving robustly stable non-inductive ramp-up, which will ultimately be necessary to demonstrate applicability of the spherical torus concept to larger devices without sufficient room for a central coil. Supported by the US DOE under the SCGSR Program.

Disks and cones: resolving the dusty torus with mid-infrared interferometry.

NASA Astrophysics Data System (ADS)

Tristram, K.

2015-09-01

The thermal emission of dust is one of the main possibilities to study the (dusty) material of the so-called "torus" in AGN. Observations using interferometry in the mid-infrared have, in the last ten years, resolved and characterised this emission beyond simple fits of spectral energy distributions, leading to a great leap forward in our view of the dusty material surrounding AGN. I will present the most recent results of such observations, obtained with the instrument MIDI. More than 25 active nuclei could be observed with MIDI, showing that the dust distributions are parsec sized. The sizes roughly scale with the square root of the luminosity, albeit with a much large scatter than in the near-infrared. Detailed studies of a few well resolved sources, among them the illustrious nuclei of NGC1068 and the Circinus galaxy, show a two component structure: an inner disk-like emission region which is surrounded by a polar elongated emitter. The latter shows differential absorption in line with the one-sided ionisation cones observed in the optical. These results are in qualitative agreement with recent hydrodynamic simulations of AGN tori. In general, they confirm the concept of a dusty obscurer providing viewing-angle dependent obscuration of the central engine.

The CLAS12 torus detector magnet at Jefferson Laboratory

DOE PAGES

Luongo, Cesar; Wiseman, Mark A.; Kashy, David H.; ...

2015-12-17

The CLAS12 Torus is a toroidal superconducting magnet, part of the detector for the 12GeV accelerator upgrade at Jefferson Lab. The coils were wound/fabricated by Fermi Lab, with Jlab responsible for all other parts of the project scope, including design, integration, cryostating the individual coils, installation, cryogenics, I&C, etc. The study provides an overview of the CLAS12 Torus magnet features, and serves as a status report of its installation in the experimental hall. Completion and commissioning of the magnet is expected in 2016.

Transparency of a magnetic cloud boundary for cosmic rays

NASA Astrophysics Data System (ADS)

Petukhov, I. S.; Petukhov, S. I.

2013-02-01

We have suggested a model of magnetic cloud presented as a torus with magnetic flux rope structure situated inside the interplanetary corona mass ejecta expanding radially away from the Sun through the interplanetary medium. The magnetic field of the torus changing during its propagation has been obtained. The magnetic cloud — solar wind boundary transparency for cosmic rays with different energies depending on the cloud orientation and properties of the torus magnetic field has been determined by means of calculation of the particle trajectories at the boundary.

Torus Breakdown and Homoclinic Chaos in a Glow Discharge Tube

NASA Astrophysics Data System (ADS)

Ginoux, Jean-Marc; Meucci, Riccardo; Euzzor, Stefano

2017-12-01

Starting from historical researches, we used, like Van der Pol and Le Corbeiller, a cubic function for modeling the current-voltage characteristic of a direct current low-pressure plasma discharge tube, i.e. a neon tube. This led us to propose a new four-dimensional autonomous dynamical system allowing to describe the experimentally observed phenomenon. Then, mathematical analysis and detailed numerical investigations of such a fourth-order torus circuit enabled to highlight bifurcation routes from torus breakdown to homoclinic chaos following the Newhouse-Ruelle-Takens scenario.

Preliminary Study of Applied Load Factors in Bumpy Air

NASA Technical Reports Server (NTRS)

Rhode, Richard V; Lundquist, Eugene E

1931-01-01

Theoretical relations involved in the study are reviewed to furnish a basis upon which experimental data can be properly analyzed. The structure of the atmosphere in relation to the load-factor problem is briefly discussed, and the acceleration data obtained on a number of flights with various airplanes are presented and analyzed to the extent that the results are applicable to n=any airplane.

Artificial Intelligence: The Bumpy Path Through Defense Acquisition

DTIC Science & Technology

2017-12-01

products through Amazon’s suite of services , or can be trained using the Alexa application to interact and control other smart products in your house...software, and capitalizing on the opportunities for customization and consultation. NVIDIA’s approach to AI hardware, offers opportunities for garage...have teamed up to provide licensing, training , and development services for a product called Unreal Engine 4, aimed at government and military

In Their Own Words: Using Self-Assessments of College Readiness to Develop Strategies for Self-Regulated Learning

ERIC Educational Resources Information Center

Verrell, Paul A.; McCabe, Norah R.

2015-01-01

The pathway to success in college can be bumpy. To smooth it we first investigated self-assessment of college readiness by undergraduates in terms of skills and habits required for college success. In a survey of almost 700 students, one of every two reported that their college work was more challenging than expected. Although 70% reported that…

A Search for Plasma "Fingers" in the Io Torus

NASA Astrophysics Data System (ADS)

Jaggar, S.; Schneider, N. M.; Bagenal, F.; Trauger, J. T.

1996-09-01

We have compared model and data images of the Io plasma torus to test the radial diffusion model of Yang et al. (J. Geophys. Res., Vol 99, p. 8755, 1994). They predict that radial diffusion takes the form of `fingers' of dense plasma flowing outward due to the centrifugal force. Furthermore, they show that the spatial scale of these significant longitudinal variations is approximately 15(o) . The observations used in this study were obtained using a 2.4m telescope at Las Campanas Observatory using a narrowband filter to isolate emissions from S(++) at 9531 Angstroms. S(++) images are dominated by emission from the warm torus where outward radial transport is expected. Although S(+) images are brighter, they are contaminated by emission from the cold torus where fingers are not expected. We used the Colorado Io Torus Emission Package (CITEP)(Taylor et al., J. Geophys. Res., Vol. 100, p. 19541, 1995) to simulate images of the torus with fingers. CITEP is a comprehensive program which incorporates accurate atomic physics, plasma physics and magnetic field models to simulate the brightness and morphology or torus emissions. We used a Voyager empirical model (Bagenal, J. Geophys. Res., Vol. 99, p. 11043, 1994) modulated by a sinusoidal longitudinal density variation with a 15(o) period and an amplitude proportional to the density at that L-shell. We compared simulated images with data to determine the minimum density contrast necessary to make fingers detectable. We place an upper limit on the density contrast of +/- 20% on a 15(o) spatial scale. We conclude that either the density contrast of this mode of transport is small, or other processes are more important for radial transport. This constraint can also be used in other radial diffusion models which predict density variations on this spatial scale. This work has been supported by NASA's Planetary Astronomy and Planetary Atmospheres programs.

Models of Electron Energetics in the Enceladus Torus

NASA Astrophysics Data System (ADS)

Cravens, T. E.; Ozak, N.; Richard, M. S.; Robertson, I. P.; Perry, M. E.; Campbell, M. E.

2010-12-01

The inner magnetosphere of Saturn contains a mixture of plasma and neutral gas, the dominant source of which is the icy satellite Enceladus. Water vapor and water dissociation products are present throughout the magnetosphere but they are particularly concentrated in a torus surrounding Saturn at the orbit of Enceladus. The Hubble Space Telescope observed OH in the torus and other neutral species (mainly water) have been measured by the Ion and Neutral Mass Spectrometer (INMS) and the Ultraviolet Imaging Spectrometer (UVIS) onboard the Cassini spacecraft. Relatively cold plasma, dominated by water group ion species, was measured by instruments onboard both the Voyager and Cassini spacecraft. The electron distribution function in this torus appears to include both a colder thermal population (seen for example by the Cassini Radio and Plasma Wave Spectrometer’s Langmuir probe -- RPWS/LP) and hotter suprathermal populations (seen by the electron spectrometer part of the Cassini plasma analyzer -- CAPS/ELS). We present a model of electron energetics in the torus. One part of this model utilizes an electron energy deposition code to determine electron fluxes versus energy. The model includes photoelectron production from the absorption of solar radiation as well as electron impact collisional processes for water and other neutral species. Another part of the model consists of an energetics code for thermal electrons that generates electron temperatures. Heating from Coulomb collisions with photoelectrons and with hot pick-up ions was included, as was cooling due to electron impact collisions with water. We show that solar radiation is the dominant source of suprathermal electrons in the core neutral torus, in agreement with recently published CAPS-ELS data. We predict electron thermal energies of about 2 eV, which is somewhat low in comparison with recently published RPWS-LP data. The implications of these results for plasma densities in the torus will also be discussed.

Magnetized hypermassive neutron-star collapse: a central engine for short gamma-ray bursts.

PubMed

Shibata, Masaru; Duez, Matthew D; Liu, Yuk Tung; Shapiro, Stuart L; Stephens, Branson C

2006-01-27

A hypermassive neutron star (HMNS) is a possible transient formed after the merger of a neutron-star binary. In the latest axisymmetric magnetohydrodynamic simulations in full general relativity, we find that a magnetized HMNS undergoes "delayed" collapse to a rotating black hole (BH) as a result of angular momentum transport via magnetic braking and the magnetorotational instability. The outcome is a BH surrounded by a massive, hot torus with a collimated magnetic field. The torus accretes onto the BH at a quasisteady accretion rate [FORMULA: SEE TEXT]; the lifetime of the torus is approximately 10 ms. The torus has a temperature [FORMULA: SEE TEXT], leading to copious ([FORMULA: SEE TEXT]) thermal radiation that could trigger a fireball. Therefore, the collapse of a HMNS is a promising scenario for generating short-duration gamma-ray bursts and an accompanying burst of gravitational waves and neutrinos.

The relationship between oral tori and bite force.

PubMed

Jeong, Chan-Woo; Kim, Kyung-Ho; Jang, Hyo-Won; Kim, Hye-Sun; Huh, Jong-Ki

2018-01-12

Objective The relationship between bite force and torus palatinus or mandibularis remains to be explained. The major aim of this study was to determine the correlation between bite force and oral tori. Methods The bite force of 345 patients was measured with a bite force recorder; impressions of the shape and size of the oral tori were taken on plaster models prior to orthodontic treatments. Subsequently, the relationship between oral tori and bite force was analyzed. Results The size, shape, and incidence of torus palatinus was not significantly correlated with bite force. However, the size of torus mandibularis increased significantly in proportion to the bite force (p = 0.020). The occurrence of different types of oral tori was not correlated with the bite force. Discussion The size of torus mandibularis provides information about bite force and can thus be used to clinically assess occlusal stress.

Embedding global and collective in a torus network with message class map based tree path selection

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

Chen, Dong; Coteus, Paul W.; Eisley, Noel A.

Embodiments of the invention provide a method, system and computer program product for embedding a global barrier and global interrupt network in a parallel computer system organized as a torus network. The computer system includes a multitude of nodes. In one embodiment, the method comprises taking inputs from a set of receivers of the nodes, dividing the inputs from the receivers into a plurality of classes, combining the inputs of each of the classes to obtain a result, and sending said result to a set of senders of the nodes. Embodiments of the invention provide a method, system and computermore » program product for embedding a collective network in a parallel computer system organized as a torus network. In one embodiment, the method comprises adding to a torus network a central collective logic to route messages among at least a group of nodes in a tree structure.« less

On the nature of S II emission from Jupiter's hot plasma torus

NASA Technical Reports Server (NTRS)

Brown, R. A.; Shemansky, D. E.

1982-01-01

An effective electron temperature T(e) of 80,000 K is indicated by the Voyager 1 encounter Jupiter hot torus emission rates in the 6731, 1256, 911 and reclassified 765 A transitions of S II. A set of 53 measurements of the S II red line doublet obtained at 5.9 Jupiter radii shows strong, irregular fluctuations in intensity, but no variation in the line ratio. At this distance from Jupiter, the torus is found to be longitudinally uniform in density; this is consonant with Voyager UVS findings, but contrary to magnetic anomaly model predictions. It is suggested that presently unidentified ion-ion and/or iron-atom reactions are responsible for the S II component irregular variations, in view of the fact that electron properties are regular and variable only over a small range in the hot torus at 5.9 Jupiter radii.

Torus Knots and the Topological Vertex

NASA Astrophysics Data System (ADS)

Jockers, Hans; Klemm, Albrecht; Soroush, Masoud

2014-08-01

We propose a class of toric Lagrangian A-branes on the resolved conifold that is suitable to describe torus knots on S 3. The key role is played by the transformation, which generates a general torus knot from the unknot. Applying the topological vertex to the proposed A-branes, we rederive the colored HOMFLY polynomials for torus knots, in agreement with the Rosso and Jones formula. We show that our A-model construction is mirror symmetric to the B-model analysis of Brini, Eynard and Mariño. Compared to the recent proposal by Aganagic and Vafa for knots on S 3, we demonstrate that the disk amplitude of the A-brane associated with any knot is sufficient to reconstruct the entire B-model spectral curve. Finally, the construction of toric Lagrangian A-branes is generalized to other local toric Calabi-Yau geometries, which paves the road to study knots in other three-manifolds such as lens spaces.

An X-Ray Spectral Model for Clumpy Tori in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Liu, Yuan; Li, Xiaobo

2014-05-01

We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, γ conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe Kα. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe Kα. The smoothing effect is mild in the low column density case (N H = 1023 cm-2), whereas it is much more evident in the high column density case (N H = 1025 cm-2). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

Instabilities of Current Carrying Torus

NASA Astrophysics Data System (ADS)

Liu, Wenjuan; Qiu, J.

2010-05-01

We investigate the initial equilibrium and stability conditions for an uniform current-carrying plasma ring with a non-trivial toroidal magnetic field Bt. Realistic parameters comparable to observations are used to describe the magnetic field inside and outside the torus. The external poloidal magnetic field is assumed to fall off as a power function with decay index n (n = - d log (Bex) /d log(h)). The parameter space is explored to find all initial equilibrium solutions, at which perturbation is introduced. It is shown that with non-trivial toroidal field, the current ring attains equilibrium with a weaker external field. It is also shown that the torus attains equilibrium at higher altitude when the external field decays more rapidly (greater n) or the ratio of the toroidal flux in the torus to the external field increases. We further study stabilities of the torus at equilibrium by defining a critical decay index ncr (Kliem and Török 2006). A sufficiently strong toroidal field can completely suppress the torus instability due to the current hoop force. With a weak toroidal field, similar to the case of Bt=0, the instability occurs when the external magnetic field declines rapidly with height when the field decay index n>ncr. For realistic sets of parameters, the equilibrium height is within 10 solar radii, and the effective ncr is in the range of 1.0-1.6. The critical decay index increases when the ratio of the toroidal flux to the external field decreases. This work is supported by NSF CAREER grant ATM-0748428.

Negative specific heat of a magnetically self-confined plasma torus

PubMed Central

Kiessling, Michael K.-H.; Neukirch, Thomas

2003-01-01

It is shown that the thermodynamic maximum-entropy principle predicts negative specific heat for a stationary, magnetically self-confined current-carrying plasma torus. Implications for the magnetic self-confinement of fusion plasma are considered. PMID:12576553

Black hole spin inferred from 3:2 epicyclic resonance model of high-frequency quasi-periodic oscillations

NASA Astrophysics Data System (ADS)

Šrámková, E.; Török, G.; Kotrlová, A.; Bakala, P.; Abramowicz, M. A.; Stuchlík, Z.; Goluchová, K.; Kluźniak, W.

2015-06-01

Estimations of black hole spin in the three Galactic microquasars GRS 1915+105, GRO J1655-40, and XTE J1550-564 have been carried out based on spectral and timing X-ray measurements and various theoretical concepts. Among others, a non-linear resonance between axisymmetric epicyclic oscillation modes of an accretion disc around a Kerr black hole has been considered as a model for the observed high-frequency quasi-periodic oscillations (HF QPOs). Estimates of spin predicted by this model have been derived based on the geodesic approximation of the accreted fluid motion. Here we assume accretion flow described by the model of a pressure-supported torus and carry out related corrections to the mass-spin estimates. We find that for dimensionless black hole spin a ≡ cJ/GM2 ≲ 0.9, the resonant eigenfrequencies are very close to those calculated for the geodesic motion. Their values slightly grow with increasing torus thickness. These findings agree well with results of a previous study carried out in the pseudo-Newtonian approximation. The situation becomes different for a ≳ 0.9, in which case the resonant eigenfrequencies rapidly decrease as the torus thickness increases. We conclude that the assumed non-geodesic effects shift the lower limit of the spin, implied for the three microquasars by the epicyclic model and independently measured masses, from a ~ 0.7 to a ~ 0.6. Their consideration furthermore confirms compatibility of the model with the rapid spin of GRS 1915+105 and provides highly testable predictions of the QPO frequencies. Individual sources with a moderate spin (a ≲ 0.9) should exhibit a smaller spread of the measured 3:2 QPO frequencies than sources with a near-extreme spin (a ~ 1). This should be further examined using the large amount of high-resolution data expected to become available with the next generation of X-ray instruments, such as the proposed Large Observatory for X-ray Timing (LOFT).

Smooth invariant densities for random switching on the torus

NASA Astrophysics Data System (ADS)

Bakhtin, Yuri; Hurth, Tobias; Lawley, Sean D.; Mattingly, Jonathan C.

2018-04-01

We consider a random dynamical system obtained by switching between the flows generated by two smooth vector fields on the 2d-torus, with the random switchings happening according to a Poisson process. Assuming that the driving vector fields are transversal to each other at all points of the torus and that each of them allows for a smooth invariant density and no periodic orbits, we prove that the switched system also has a smooth invariant density, for every switching rate. Our approach is based on an integration by parts formula inspired by techniques from Malliavin calculus.

Scientific program in planetary atmospheric studies

NASA Technical Reports Server (NTRS)

Broadfoot, A. L.

1983-01-01

The Voyager encounters with Jupiter led to two main areas of investigation: (1) the definition of the structure and composition of the upper atmosphere and the interaction of the magnetosphere and atmosphere, and (2) the study of the plasma torus using the EUV (Extreme Ultraviolet) data in conjunction with ground-based and in-situ measurements. In the course of these investigations, the atmosphere studies were extended to a comparative study with the bound atmospheres of Saturn and Titan; and the torus study expanded to include the extended atmospheres of Titan (the H torus) and the rings of Saturn.

Analysis of a thin-walled pressurized torus in contact with a plane. [aircraft tires study

NASA Technical Reports Server (NTRS)

Mack, M. J., Jr.; Gassman, P. M.; Baumgarten, J. R.

1983-01-01

Finite element analysis is applied to study the large deflection of a standing torus loaded by a plane. The internally pressurized thin-walled structure is found to have an elliptical footprint area. Considerable bulge occurs in the sidewall in the region of the load plane. Stress distributions throughout the torus are shown for various load levels and for various modeling strategies at a given load level. In large load ranges finite element calculations show compressive circumferential stress and negative curvature in the footprint region. Results are compared with inelastic wall analysis.

Spherical torus fusion reactor

DOEpatents

Martin Peng, Y.K.M.

1985-10-03

The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement fusion reactor in which only the indispensable components inboard of a tokamak type of plasma confinement region, mainly a current conducting medium which carries electrical current for producing a toroidal magnet confinement field about the toroidal plasma region, are retained.

Spheromak plasma flow injection into a torus chamber and the HIST plasmas

NASA Astrophysics Data System (ADS)

Hatuzaki, Akinori

2005-10-01

The importance of plasma flow or two-fluid effect is recognized in understanding the relaxed states of high-beta torus plasmas, start-up and current drive by non-coaxial helicity injection, magnetic reconnection and plasma dynamo in fusion, laboratory and space plasmas. As a new approach to create a flowing two-fluid plasma equilibrium, we have tried to inject tangentially the plasma flow with spheromak-type magnetic configurations into a torus vacuum chamber with an external toroidal magnetic field (TF) coil. In the initial experiments, the RFP-like configuration with helical magnetic structures was realized in the torus vessel. The ion flow measurement with Mach probes showed that the ion flow keeps the same direction despite the reversal of the toroidal current and the axial electric field. The ion fluid comes to flow in the opposite direction to the electron fluid by the reversal of TF. This result suggests that not only electron but also ion flow contributes significantly on the reversed toroidal current. In this case, the ratio of ui to the electron flow velocity ue is estimated as ui/ue ˜ 1/2. We also will inject the spheromak flow into the HIST spherical torus plasmas to examine the possibilities to embedding the two-fluid effect in the ST plasmas.

Mechanism of water-stress induced cavitation in conifers: bordered pit structure and function support the hypothesis of seal capillary-seeding

PubMed Central

DELZON, SYLVAIN; DOUTHE, CYRIL; SALA, ANNA; COCHARD, HERVE

2010-01-01

Resistance to water-stress induced cavitation is an important indicator of drought tolerance in woody species and is known to be intimately linked to the anatomy of the xylem. However, the actual mechanical properties of the pit membrane are not well known and the exact mode of air-seeding by which cavitation occurs is still uncertain. We examined the relationship between cavitation resistance and bordered pit structure and function in 40 coniferous species. Xylem pressure inducing 50% loss of hydraulic conductance (P50, a proxy for cavitation resistance) varied widely among species, from −2.9 to −11.3 MPa. The valve effect of the pit membrane, measured as a function of margo flexibility and torus overlap, explained more variation in cavitation-resistance than simple anatomical traits such as pit membrane, pit aperture or torus size. Highly cavitation resistant species exhibited both a high flexibility of the margo and a large overlap between the torus and the pit aperture, allowing the torus to tightly seal the pit aperture. Our results support the hypothesis of seal capillary-seeding as the most likely mode of air-seeding, and suggest that the adhesion of the torus to the pit border may be the main determinant of cavitation resistance in conifers. PMID:20636490

Mechanism of water-stress induced cavitation in conifers: bordered pit structure and function support the hypothesis of seal capillary-seeding.

PubMed

Delzon, Sylvain; Douthe, Cyril; Sala, Anna; Cochard, Herve

2010-12-01

Resistance to water-stress induced cavitation is an important indicator of drought tolerance in woody species and is known to be intimately linked to the anatomy of the xylem. However, the actual mechanical properties of the pit membrane are not well known and the exact mode of air-seeding by which cavitation occurs is still uncertain. We examined the relationship between cavitation resistance and bordered pit structure and function in 40 coniferous species. Xylem pressure inducing 50% loss of hydraulic conductance (P(50), a proxy for cavitation resistance) varied widely among species, from -2.9 to -11.3 MPa. The valve effect of the pit membrane, measured as a function of margo flexibility and torus overlap, explained more variation in cavitation-resistance than simple anatomical traits such as pit membrane, pit aperture or torus size. Highly cavitation resistant species exhibited both a high flexibility of the margo and a large overlap between the torus and the pit aperture, allowing the torus to tightly seal the pit aperture. Our results support the hypothesis of seal capillary-seeding as the most likely mode of air-seeding, and suggest that the adhesion of the torus to the pit border may be the main determinant of cavitation resistance in conifers. © 2010 Blackwell Publishing Ltd.

Torus Approach in Gravity Field Determination from Simulated GOCE Gravity Gradients

NASA Astrophysics Data System (ADS)

Liu, Huanling; Wen, Hanjiang; Xu, Xinyu; Zhu, Guangbin

2016-08-01

In Torus approach, observations are projected to the nominal orbits with constant radius and inclination, lumped coefficients provides a linear relationship between observations and spherical harmonic coefficients. Based on the relationship, two-dimensional FFT and block-diagonal least-squares adjustment are used to recover Earth's gravity field model. The Earth's gravity field model complete to degree and order 200 is recovered using simulated satellite gravity gradients on a torus grid, and the degree median error is smaller than 10-18, which shows the effectiveness of Torus approach. EGM2008 is employed as a reference model and the gravity field model is resolved using the simulated observations without noise given on GOCE orbits of 61 days. The error from reduction and interpolation can be mitigated by iterations. Due to polar gap, the precision of low-order coefficients is lower. Without considering these coefficients the maximum geoid degree error and cumulative error are 0.022mm and 0.099mm, respectively. The Earth's gravity field model is also recovered from simulated observations with white noise 5mE/Hz1/2, which is compared to that from direct method. In conclusion, it is demonstrated that Torus approach is a valid method for processing massive amount of GOCE gravity gradients.

Identifying messaging completion in a parallel computer by checking for change in message received and transmitted count at each node

DOEpatents

Archer, Charles J [Rochester, MN; Hardwick, Camesha R [Fayetteville, NC; McCarthy, Patrick J [Rochester, MN; Wallenfelt, Brian P [Eden Prairie, MN

2009-06-23

Methods, parallel computers, and products are provided for identifying messaging completion on a parallel computer. The parallel computer includes a plurality of compute nodes, the compute nodes coupled for data communications by at least two independent data communications networks including a binary tree data communications network optimal for collective operations that organizes the nodes as a tree and a torus data communications network optimal for point to point operations that organizes the nodes as a torus. Embodiments include reading all counters at each node of the torus data communications network; calculating at each node a current node value in dependence upon the values read from the counters at each node; and determining for all nodes whether the current node value for each node is the same as a previously calculated node value for each node. If the current node is the same as the previously calculated node value for all nodes of the torus data communications network, embodiments include determining that messaging is complete and if the current node is not the same as the previously calculated node value for all nodes of the torus data communications network, embodiments include determining that messaging is currently incomplete.

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

Nelson, Andrew F.; Marzari, F., E-mail: andy.nelson@lanl.gov, E-mail: francesco.marzari@pd.infn.it

We present two-dimensional hydrodynamic simulations using the Smoothed Particle Hydrodynamic code, VINE, to model a self-gravitating binary system. We model configurations in which a circumbinary torus+disk surrounds a pair of stars in orbit around each other and a circumstellar disk surrounds each star, similar to that observed for the GG Tau A system. We assume that the disks cool as blackbodies, using rates determined independently at each location in the disk by the time dependent temperature of the photosphere there. We assume heating due to hydrodynamical processes and to radiation from the two stars, using rates approximated from a measuremore » of the radiation intercepted by the disk at its photosphere. We simulate a suite of systems configured with semimajor axes of either a = 62 AU (“wide”) or a = 32 AU (“close”), and with assumed orbital eccentricity of either e = 0 or e = 0.3. Each simulation follows the evolution for ∼6500–7500 yr, corresponding to about three orbits of the torus around the center of mass. Our simulations show that strong, sharply defined spiral structures are generated from the stirring action of the binary and that, in some cases, these structures fragment into 1–2 massive clumps. The torus quickly fragments into several dozen such fragments in configurations in which either the binary is replaced by a single star of equal mass, or radiative heating is neglected. The spiral structures extend inwards to the circumstellar environment as large scale material streams for which most material is found on trajectories that return it to the torus on a timescale of 1–200 yr, with only a small fraction accreting into the circumstellar environment. The spiral structures also propagate outwards through the torus, generating net outwards mass flow, and eventually losing coherence at large distances from the stars. The torus becomes significantly eccentric in shape over most of its evolution. In all configurations, accretion onto the stars occurs at a steady rate of a few ×10{sup −8} M {sub ⊙} yr{sup −1}, with the net result that, without replenishment, the disk lifetimes would be shorter than ∼10{sup 4} yr. Our simulations show that only wide orbit configurations are able to retain circumstellar disks, by virtue of accretion driven from the robust material streams generated in wide configurations, which are very weak in close configurations. In wide, eccentric orbit configurations, accretion is episodic and occurs preferentially onto the secondary, with rates strongly peaked near the binary periapse. Based on our results, we conclude that the GG Tau A torus is strongly self gravitating and that a major contribution to its thermal energy input is the shock dissipation associated with spiral structures generated both by self gravitating disturbances and by the stirring action of the binary. We interpret the sharply defined features observed in the torus as manifestations of such spiral structures. We interpret the low density disk surrounding it as an excretion disk created by the outward mass flux generated by the spiral arms as they propagate outwards. Typical eccentricities calculated for the shape of the tori modeled in our simulations are large enough to account for the supposed ∼20° mutual inclination between the stellar orbit plane of GG Tau A and its surrounding torus through a degeneracy between the interpretation of inclination of the torus and its eccentricity. We therefore interpret the observations in favor of a coplanar system with an eccentric torus. Because accretion onto the disks occurs at rates sufficient to sustain them only in wide orbit configurations, we conclude that the gas currently resident in the circumstellar disks of the GG Tau A system has been accreted from the torus within the past few thousand years. Although circumstellar disks will persist over time spans long enough to permit planet formation, the overall environment remains unfavorable due to high temperatures and other conditions. Given the presence of circumstellar disks, robust accretion streams, and our interpretation of the GG Tau A stellar orbit plane as coplanar with the torus surrounding it, we conclude that the GG Tau A system is in an eccentric, a ∼ 62 AU orbit, resolving questions in the literature regarding its orbit parameters.« less

Turnip Yellow Mosaic Virus

NASA Technical Reports Server (NTRS)

2000-01-01

The bumpy exterior of the turnip yellow mosaic virus (TYMV) protein coat, or capsid, was defined in detail by Dr. Alexander McPherson of the University of California, Irvin using proteins crystallized in space for analysis on Earth. TYMV is an icosahedral virus constructed from 180 copies of the same protein arranged into 12 clusters of five proteins (pentamers), and 20 clusters of six proteins (hexamers). The final TYMV structure led to the unexpected hypothesis that the virus releases its RNA by essentially chemical-mechanical means. Most viruses have fairly flat coats, but in TYNV, the fold in each protein, called the jellyroll, is clustered at the points where the protein pentamers and hexamers join. The jellyrolls are almost standing on end, producing a bumpy surface with knobs at all of the pentamers and hexamers. At the inside surface of the pentamers is a void that is not present at the hexamers. The coating had been seen in early stuties of TYMV, but McPherson's atomic structure shows much more detail. The inside surface is strikingly, and unexpectedly, different than the outside. While the pentamers contain a central void on the inside, the hexameric units contain peptides linked to each other, forming a ring or, more accurately, rings to fill the void. Credit: Dr. Alexander McPherson, University of California, Irvine

Microgravity

NASA Image and Video Library

2000-05-01

The bumpy exterior of the turnip yellow mosaic virus (TYMV) protein coat, or capsid, was defined in detail by Dr. Alexander McPherson of the University of California, Irvin using protein crystallized in space for analysis on Earth. TYMV is an icosahedral virus constructed from 180 copies of the same protein arranged into 12 clusters of five proteins (pentamers), and 20 clusters of six proteins (hexamers). The final TYMV structure led to the enexpected hypothesis that the virus release its RNA by essentially chemical-mechanical means. Most viruses have farly flat coats, but in TYMV, the fold in each protein, called the jellyroll, is clustered at the points where the protein pentamers and hexamers join. The jellyrolls are almost standing on end, producing a bumpy surface with knobs at all of the pentamers and hexamers. At the inside surface of the pentamers is a void that is not present at the hexamers. The coating had been seen in early studies of TYMV, but McPhereson's atomic structure shows much more detail. The inside surface is strikingly, and unexpectedly, different than the outside. While the pentamers contain a central viod on the inside, the hexameric units contain peptides liked to each other, forming a ring or, more accurately, rings to fill the voild. Credit: Dr. Alexander McPherson, University of California, Irvine.

Turnip Yellow Mosaic Virus Structure

NASA Technical Reports Server (NTRS)

2000-01-01

The bumpy exterior of the turnip yellow mosaic virus (TYMV) protein coat, or capsid, was defined in detail by Dr. Alexander McPherson of the University of California, Irvin using protein crystallized in space for analysis on Earth. TYMV is an icosahedral virus constructed from 180 copies of the same protein arranged into 12 clusters of five proteins (pentamers), and 20 clusters of six proteins (hexamers). The final TYMV structure led to the enexpected hypothesis that the virus release its RNA by essentially chemical-mechanical means. Most viruses have farly flat coats, but in TYMV, the fold in each protein, called the jellyroll, is clustered at the points where the protein pentamers and hexamers join. The jellyrolls are almost standing on end, producing a bumpy surface with knobs at all of the pentamers and hexamers. At the inside surface of the pentamers is a void that is not present at the hexamers. The coating had been seen in early studies of TYMV, but McPhereson's atomic structure shows much more detail. The inside surface is strikingly, and unexpectedly, different than the outside. While the pentamers contain a central viod on the inside, the hexameric units contain peptides liked to each other, forming a ring or, more accurately, rings to fill the voild. Credit: Dr. Alexander McPherson, University of California, Irvine.

Microgravity

NASA Image and Video Library

2000-05-01

The bumpy exterior of the turnip yellow mosaic virus (TYMV) protein coat, or capsid, was defined in detail by Dr. Alexander McPherson of the University of California, Irvin using proteins crystallized in space for analysis on Earth. TYMV is an icosahedral virus constructed from 180 copies of the same protein arranged into 12 clusters of five proteins (pentamers), and 20 clusters of six proteins (hexamers). The final TYMV structure led to the unexpected hypothesis that the virus releases its RNA by essentially chemical-mechanical means. Most viruses have fairly flat coats, but in TYNV, the fold in each protein, called the jellyroll, is clustered at the points where the protein pentamers and hexamers join. The jellyrolls are almost standing on end, producing a bumpy surface with knobs at all of the pentamers and hexamers. At the inside surface of the pentamers is a void that is not present at the hexamers. The coating had been seen in early stuties of TYMV, but McPherson's atomic structure shows much more detail. The inside surface is strikingly, and unexpectedly, different than the outside. While the pentamers contain a central void on the inside, the hexameric units contain peptides linked to each other, forming a ring or, more accurately, rings to fill the void. Credit: Dr. Alexander McPherson, University of California, Irvine

Formation of the oxygen torus in the inner magnetosphere: Van Allen Probes observations

DOE PAGES

Nose, Masahito; Oimatsu, S.; Keika, K.; ...

2015-02-19

Here we study the formation process of an oxygen torus during the 12–15 November 2012 magnetic storm, using the magnetic field and plasma wave data obtained by Van Allen Probes. We estimate the local plasma mass density (ρ L) and the local electron number density (n eL) from the resonant frequencies of standing Alfvén waves and the upper hybrid resonance band. The average ion mass (M) can be calculated by M ~ ρ L/n eL under the assumption of quasi-neutrality of plasma. During the storm recovery phase, both Probe A and Probe B observe the oxygen torus at L =more » 3.0–4.0 and L = 3.7–4.5, respectively, on the morning side. The oxygen torus has M = 4.5–8 amu and extends around the plasmapause that is identified at L~3.2–3.9. We find that during the initial phase, M is 4–7 amu throughout the plasma trough and remains at ~1 amu in the plasmasphere, implying that ionospheric O + ions are supplied into the inner magnetosphere already in the initial phase of the magnetic storm. Numerical calculation under a decrease of the convection electric field reveals that some of thermal O + ions distributed throughout the plasma trough are trapped within the expanded plasmasphere, whereas some of them drift around the plasmapause on the dawnside. This creates the oxygen torus spreading near the plasmapause, which is consistent with the Van Allen Probes observations. We conclude that the oxygen torus identified in this study favors the formation scenario of supplying O + in the inner magnetosphere during the initial phase and subsequent drift during the recovery phase.« less

Diagnosing the Kinematics of the Tori in Active Galactic Nuclei with the Velocity-resolved Reverberation Mapping of the Narrow Iron K α Line

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

Liu Yuan; Li Xiaobo, E-mail: liuyuan@ihep.ac.cn, E-mail: lixb@ihep.ac.cn

The properties of the dusty tori in active galactic nuclei (AGNs) have been investigated in detail, mainly focusing on the geometry and components; however, the kinematics of the torus are still not clear. The narrow iron K α line at 6.4 keV is thought to be produced by the X-ray reflection from the torus. Thus, the velocity-resolved reverberation mapping of it is able to constrain the kinematics of the torus. Such effort is limited by the spectral resolution of current charged coupled device (CCD) detectors and should be possible with the microcalorimeter on the next generation X-ray satellite. In thismore » paper, we first construct the response functions of the torus under a uniform inflow, a Keplerian rotation, and a uniform outflow. Then the energy-dependent light curve of the narrow iron K α line is simulated according to the performance of the X-ray Integral Field Unit in Athena. Finally, the energy-dependent cross-correlation function is calculated to reveal the kinematic signal. According to our results, 100 observations with 5 ks exposure of each are sufficient to distinguish the above three velocity fields. Although the real geometry and velocity field of the torus could be more complex than we assumed, the present result proves the feasibility of the velocity-resolved reverberation mapping of the narrow iron K α line. The combination of the dynamics of the torus with those of the broad-line region and the host galaxy is instructive for the understanding of the feeding and feedback process of AGNs.« less

Numerical Simulation of Rotation-Driven Plasma Transport In the Jovian Magnetosphere

NASA Technical Reports Server (NTRS)

Wolf, Richard A.

1997-01-01

A Jupiter version of the Rice Convection Model (RCM-J) was developed with support of an earlier NASA SR&T grant. The conversion from Earth to Jupiter included adding currents driven by centrifugal force, reversing the planetary magnetic field, and rescaling various parameters. A series of informative runs was carried out, all of them solving initial value problems. The simulations followed an initial plasma torus configuration as it fell apart by interchange instability. Some conclusions from the simulations were the following: 1. We confirmed that, for conventional values of the torus density and ionospheric conductance, the torus disintegrates by interchange instability on a time scale of approx. one day, which is 1-2 orders of magnitude shorter than the best estimates of the average residence time of plasma in the torus. 2. In the model, the instability could be slowed to an arbitrary degree by the addition of sufficient impounding energetic particles, as suggested earlier by Siscoe et al (1981). However, the observed energetic particles do not seem sufficient to guarantee impoundment (e.g., Mauk et al., 1996). 3. Whether inhibited by impoundment or not, the interchange was found to proceed by the formation of long fingers, which get thinner as they get longer. This picture differed dramatically from the conventional radial-diffusion picture (e.g., Siscoe and Summers (1981)), more superficially with the outward-moving-blob picture (Pontius and Hill, 1989). The obvious limitation of the original RCM-J was that it could not represent a plasma source. We could represent the decay of a pre-existing torus, but we could not represent the way ionization of material from Io continually replenishes the plasma. We consequently were precluded from studying a whole set of fundamental issues of torus theory, including whether the system can come to a steady state.

System III variations in apparent distance of Io plasma torus from Jupiter

NASA Technical Reports Server (NTRS)

Dessler, A. J.; Sandel, B. R.

1992-01-01

System III variations in apparent distance of the Io plasma torus from Jupiter are examined on the basis of data obtained from UVS scans across Jupiter's satellite system. The displacement of the dawn and dusk ansae are found to be unexpectedly complex. The displacements are unequal and both ansae are in motion with the motion of the approaching ansa being the lesser of the two. The radial motions, as measured from either the center of Jupiter or the offset-tilted dipole, are of unequal magnitude and have the System III periodicity. It is concluded that the cross-tail electric field that causes these torus motions is concentrated on the dusk ansa, varied with the System III period, and shows magnetic-anomaly phase control. It is found that the dawn-dust asymmetry in brightness is not explained simply by the cross-tail electric field. It is concluded that there is a heating mechanism that causes the dusk side of the Io plasma torus to be brighter than the dawn side.

Near-infrared morphology of protoplanetary nebulae - The icy dust torus of Minkowski's Footprint (M1-92)

NASA Technical Reports Server (NTRS)

Eiroa, C.; Hodapp, K.-W.

1989-01-01

High-resolution near-infrared images and ice-band spectra of the protoplanetary nebula M1-92 (Minkowski's Footprint) are presented. The direct images of the object display a typical bipolar morphology with the star located in the center of the nebula illuminating two lobes. The overall dimensions are the same in the J, H, and K infrared bands, and they are similar to those in the optical range. The near-infrared color images clearly reveal a dust torus around the central star. The orientation of the object in the plane of the sky allows the simultaneous view of the illuminating star, the nebular lobes, and the dust torus in a highly favorable perspective, only rarely found in other bipolar nebulae. The ice-band spectra make it possible to locate the H2O-ice grains within the dust torus; in addition, the narrow ice feature indicates that the ices are primarily pure crystalline water.

A comprehensive model of ion diffusion and charge exchange in the cold Io torus

NASA Technical Reports Server (NTRS)

Barbosa, D. D.; Moreno, M. A.

1988-01-01

A comprehensive analytic model of radial diffusion in the cold Io torus is developed. The model involves a generalized molecular cloud theory of SO2 and its dissociation fragments SO, O2, S, and O, which are formed at a relatively large rate by solar UV photodissociation of SO2. The key component of the new theory is SO, which can react with S(+) through a near-resonant charge exchange process that is exothermic. This provides a mechanism for the rapid depletion of singly ionized sulfur in the cold torus and can account for the large decrease in the total flux tube content inward of Io's orbit. The model is used to demonstrate quantitatively the effects of radial diffusion in a charge exchange environment that acts as a combined source and sink for ions in various charge states. A detailed quantitative explanation for the O(2+) component of the cold torus is given, and insight is derived into the workings of the so-called plasma 'ribbon'.

Magnetization switching process in a torus nanoring with easy-plane surface anisotropy

NASA Astrophysics Data System (ADS)

Alzate-Cardona, J. D.; Sabogal-Suárez, D.; Restrepo-Parra, E.

2017-11-01

We have studied the effects of surface shape anisotropy in the magnetization behavior of a torus nanoring by means of Monte Carlo simulations. Stable states (vortex and reverse vortex states) and metastable states (onion and asymmetric onion states) were found in the torus nanoring. The probability of occurrence of the metastable states (stable states) tends to decrease (increase) as the amount of Monte Carlo steps per spin, temperature steps and negative values of the anisotropy constant increase. We evaluated under which conditions it is possible to switch the magnetic state of the torus nanoring from a vortex to a reverse vortex state by applying a circular magnetic field at certain temperature interval. The switching probability (from a vortex to a reverse vortex state) depends on the value of the current intensity, which generates the circular magnetic field, and the temperature interval where the magnetic field is applied. There is a linear relationship between the current intensity and the minimum temperature interval above which the vortex state can be switched.

An Axisymmetric Hydrodynamical Model for the Torus Wind in AGN. 2; X-ray Excited Funnel Flow

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2008-01-01

We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra.

Embedding global barrier and collective in torus network with each node combining input from receivers according to class map for output to senders

DOEpatents

Chen, Dong; Coteus, Paul W; Eisley, Noel A; Gara, Alan; Heidelberger, Philip; Senger, Robert M; Salapura, Valentina; Steinmacher-Burow, Burkhard; Sugawara, Yutaka; Takken, Todd E

2013-08-27

Embodiments of the invention provide a method, system and computer program product for embedding a global barrier and global interrupt network in a parallel computer system organized as a torus network. The computer system includes a multitude of nodes. In one embodiment, the method comprises taking inputs from a set of receivers of the nodes, dividing the inputs from the receivers into a plurality of classes, combining the inputs of each of the classes to obtain a result, and sending said result to a set of senders of the nodes. Embodiments of the invention provide a method, system and computer program product for embedding a collective network in a parallel computer system organized as a torus network. In one embodiment, the method comprises adding to a torus network a central collective logic to route messages among at least a group of nodes in a tree structure.

Suzaku View of the Swift/BAT Active Galactic Nuclei. V. Torus Structure of Two Luminous Radio-Loud Active Galactic Nuclei (3C 206 and PKS 0707-35)

NASA Technical Reports Server (NTRS)

Tazaki, Fumie; Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard F.; Tombesi, Francesco

2013-01-01

We present the results from broadband X-ray spectral analysis of 3C 206 and PKS 0707-35 with Suzaku and Swift/BAT, two of the most luminous unobscured and obscured radio-loud active galactic nuclei (AGNs) with hard X-ray luminosities of 10(sup 45.5) erg per second and 10(sup 44.9) erg per second (14-195 keV), respectively. Based on the radio core luminosity, we estimate that the X-ray spectrum of 3C 206 contains a significant (60% in the 14-195 keV band) contribution from the jet, while it is negligible in PKS 0707-35.We can successfully model the spectra with the jet component (for 3C 206), the transmitted emission, and two reflection components from the torus and the accretion disk. The reflection strengths from the torus are found to be R(sub torus)(=Omega/2pi) = 0.29 +/- 0.18 and 0.41 +/- 0.18 for 3C 206 and PKS 0707-35, respectively, which are smaller than those in typical Seyfert galaxies. Utilizing the torus model by Ikeda et al., we quantify the relation between the half-opening angle of a torus (theta(sub oa)) and the equivalent width of an iron-K line. The observed equivalent width of 3C 206, less than 71 eV, constrains the column density in the equatorial plane to N(sup eq)(sub H) lesst han 10(sup 23) per square centimeter, or the half-opening angle to theta(sub oa) greater than 80 deg. if N(sup eq)(sub H) = 10(sup 24) per square centimeter is assumed. That of PKS 0707-35, 72 +/- 36 eV, is consistent with N(sup eq)(sub H) 10(sup 23) per square centimeter. Our results suggest that the tori in luminous radio-loud AGNs are only poorly developed. The trend is similar to that seen in radio-quiet AGNs, implying that the torus structure is not different between AGNs with jets and without jets.

The canonical quantization of chaotic maps on the torus

NASA Astrophysics Data System (ADS)

Rubin, Ron Shai

In this thesis, a quantization method for classical maps on the torus is presented. The quantum algebra of observables is defined as the quantization of measurable functions on the torus with generators exp (2/pi ix) and exp (2/pi ip). The Hilbert space we use remains the infinite-dimensional L2/ (/IR, dx). The dynamics is given by a unitary quantum propagator such that as /hbar /to 0, the classical dynamics is returned. We construct such a quantization for the Kronecker map, the cat map, the baker's map, the kick map, and the Harper map. For the cat map, we find the same for the propagator on the plane the same integral kernel conjectured in (HB) using semiclassical methods. We also define a quantum 'integral over phase space' as a trace over the quantum algebra. Using this definition, we proceed to define quantum ergodicity and mixing for maps on the torus. We prove that the quantum cat map and Kronecker map are both ergodic, but only the cat map is mixing, true to its classical origins. For Planck's constant satisfying the integrality condition h = 1/N, with N/in doubz+, we construct an explicit isomorphism between L2/ (/IR, dx) and the Hilbert space of sections of an N-dimensional vector bundle over a θ-torus T2 of boundary conditions. The basis functions are distributions in L2/ (/IR, dx), given by an infinite comb of Dirac δ-functions. In Bargmann space these distributions take on the form of Jacobi ϑ-functions. Transformations from position to momentum representation can be implemented via a finite N-dimensional discrete Fourier transform. With the θ-torus, we provide a connection between the finite-dimensional quantum maps given in the physics literature and the canonical quantization presented here and found in the language of pseudo-differential operators elsewhere in mathematics circles. Specifically, at a fixed point of the dynamics on the θ-torus, we return a finite-dimensional matrix propagator. We present this connection explicitly for several examples.

An Investigation into the Electromagnetic Interactions between a Superconducting Torus and Solenoid for the Jefferson Lab 12 GeV Upgrade

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

Rajput-Ghoshal, Renuka; Ghoshal, Probir K.; Fair, Ruben J.

2015-06-01

The Jefferson Lab 12 GeV Upgrade in Hall B will need CLAS12 detector that requires two superconducting magnets. One is a magnet system consisting of six superconducting trapezoidal racetrack-type coils assembled in a Toroidal configuration (Torus) and the second is an actively shielded solenoidal magnet (Solenoid). Both the torus and solenoid are located in close proximity to one another and are surrounded by sensitive detectors. This paper investigates the electromagnetic interactions between the two systems during normal operation as well as during various fault scenarios as part of a Risk Assessment and Mitigation (RAM).

An Axisymmetric, Hydrodynamical Model for the Torus Wind in Active Galactic Nuclei

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2008-01-01

We report on time-dependent axisymmetric simulations of an X-ray-excited flow from a parsec-scale, rotating, cold torus around an active galactic nucleus. Our simulations account for radiative heating and cooling and radiation pressure force. The simulations follow the development of a broad biconical outflow induced mainly by X-ray heating. We compute synthetic spectra predicted by our simulations. The wind characteristics and the spectra support the hypothesis that a rotationally supported torus can serve as the source of a wind which is responsible for the warm absorber gas observed in the X-ray spectra of many Seyfert galaxies.

The atomic hydrogen cloud in the saturnian system

NASA Astrophysics Data System (ADS)

Tseng, W.-L.; Johnson, R. E.; Ip, W.-H.

2013-09-01

The importance of Titan's H torus shaped by solar radiation pressure and of hydrogen atoms flowing out of Saturn's atmosphere in forming the broad hydrogen cloud in Saturn's magnetosphere is still debated. Since the Saturnian system also contains a water product torus which originates from the Enceladus plumes, the icy ring particles, and the inner icy satellites, as well as Titan's H2 torus, we have carried out a global investigation of the atomic hydrogen cloud taking into account all sources. We show that the velocity and angle distributions of the hot H ejected from Saturn's atmosphere following electron-impact dissociation of H2 are modified by collisions with the ambient atmospheric H2 and H. This in turn affects the morphology of the escaping hydrogen from Saturn, as does the morphology of the ionospheric electron distribution. Although an exact agreement with the Cassini observations is not obtained, our simulations show that H directly escaping from Titan is the dominant contributor in the outer magnetosphere. Of the total number of H observed by Cassini from 1 to 5RS, ∼5.7×1034, our simulations suggest ∼20% is from dissociation in the Enceladus torus, ∼5-10% is from dissociation of H2 in the atmosphere of the main rings, and ∼50% is from Titan's H torus, implying that ∼20% comes from Saturn atmosphere.

A ground-based experimental test program to duplicate and study the spacecraft glow phenomenon

NASA Technical Reports Server (NTRS)

Langer, W. D.; Cohen, S. A.; Manos, D. M.; Mcneill, D. H.; Motley, R. W.; Ono, M.; Paul, S.

1985-01-01

The use of a plasma device, the Advanced Concepts Torus-I, for producing atoms and molecules to study spacecraft glow mechanisms is discussed. A biased metal plate, located in the plasma edge, is used to accelerate and neutralize plasma ions, thus generating a neutral beam with a flux approx. 5 x 10 to the 14th power/sq cm/sec at the end of a drift tube. Our initial experiments are to produce a 10 eV molecular and atomic nitrogen beam directed onto material targets. Photon emission in the spectral range 2000 to 9000 A from excited species formed on the target surface will be investigated.

FMEA on the superconducting torus for the Jefferson Lab 12 GeV accelerator upgrade

DOE PAGES

Ghoshal, Probir K.; Biallas, George H.; Fair, Ruben J.; ...

2015-01-16

As part of the Jefferson Lab 12GeV accelerator upgrade project, Hall B requires two conduction cooled superconducting magnets. One is a magnet system consisting of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration and the second is an actively shielded solenoidal magnet system consisting of 5 coils. Both magnets are to be wound with Superconducting Super Collider-36 NbTi strand Rutherford cable soldered into a copper channel. This paper describes the various failure modes in torus magnet along with the failure modes that could be experienced by the torus and its interaction with the solenoid which is located inmore » close proximity.« less

Spherical torus fusion reactor

DOEpatents

Peng, Yueng-Kay M.

1989-04-04

A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.

Spherical torus fusion reactor

DOEpatents

Peng, Yueng-Kay M.

1989-01-01

A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.

Observations of reduced electron Gyroscale fluctuations in national spherical torus experiment H-mode plasmas with large ExB flow shear.

PubMed

Smith, D R; Kaye, S M; Lee, W; Mazzucato, E; Park, H K; Bell, R E; Domier, C W; Leblanc, B P; Levinton, F M; Luhmann, N C; Menard, J E; Yuh, H

2009-06-05

Electron gyroscale fluctuation measurements in National Spherical Torus Experiment H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temperature gradient (ETG) turbulence. Large toroidal rotation in National Spherical Torus Experiment plasmas with neutral beam injection generates ExB flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the ExB flow shear rate exceeds ETG linear growth rates. The observations indicate that ExB flow shear can be an effective suppression mechanism for ETG turbulence.

Observations of electron gyroharmonic waves and the structure of the Io torus. [jupiter 1 spacecraft radio astronomy experiment

NASA Technical Reports Server (NTRS)

Birmingham, T. J.; Alexander, J. K.; Desch, M. D.; Hubbard, R. F.; Pedersen, B. M.

1980-01-01

Narrow-banded emissions were observed by the Planetary Radio Astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near the upper hybrid resonant frequency, (fuhr) but the distribution of the other observed emissions varies in a systematic way with position in the torus. A refined model of the electron density variation, based on identification of the fuhr line, is included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot losscone electrons. The positioning of the observed auxiliary harmonics with respect to fuhr is shown to be an indicator of the cold to hot temperature ratio. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner and outer portions of the torus.

Injection of Compact Torus into the HIST spherical torus plasmas

NASA Astrophysics Data System (ADS)

Sugawara, M.; Katsumoto, S.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2006-10-01

The three-dimensional interaction of a spheromak-like compact torus (CT) plasma with spherical torus (ST) plasmas has been experimentally studied to understand magnetic reconnection, helicity current drive, particle fuelling and Alfvén wave excitation [1]. We have examined how the sign of helicity (Co-HI and Counter-HI) of the injected CT influences on the ST plasmas on HIST [2]. The dynamics of the CT have been identified to be significantly different between the both injection cases. Time-frequency analysis shows that the fluctuation induced in the co-HI case has the maximum spectral amplitude at around 300 -- 400 kHz that may indicate the magnetic reconnection. In this case, the CT particle is released quickly at a periphery region, but on the other hand, for the counter-HI case, the CT could penetrate deeply into the core region as accompanied by Alfvén wave due to no magnetic reconnection. [1] M. Nagata, et al., Nucl. Fusion 45, 1056 (2005) [2] M. Nagata, et al., Physics of Plasmas 10, 2932 (2003)

Testing holography using lattice super-Yang-Mills theory on a 2-torus

NASA Astrophysics Data System (ADS)

Catterall, Simon; Jha, Raghav G.; Schaich, David; Wiseman, Toby

2018-04-01

We consider maximally supersymmetric SU (N ) Yang-Mills theory in Euclidean signature compactified on a flat two-dimensional torus with antiperiodic ("thermal") fermion boundary conditions imposed on one cycle. At large N , holography predicts that this theory describes certain black hole solutions in type IIA and IIB supergravity, and we use lattice gauge theory to test this. Unlike the one-dimensional quantum mechanics case where there is only the dimensionless temperature to vary, here we emphasize there are two more parameters which determine the shape of the flat torus. While a rectangular Euclidean torus yields a thermal interpretation, allowing for skewed tori modifies the holographic dual black hole predictions and results in another direction to test holography. Our lattice calculations are based on a supersymmetric formulation naturally adapted to a particular skewing. Using this we perform simulations up to N =16 with several lattice spacings for both skewed and rectangular tori. We observe the two expected black hole phases with their predicted behavior, with a transition between them that is consistent with the gravity prediction based on the Gregory-Laflamme transition.

Periodic intensity variations in sulfur emissions from the Io plasma torus

NASA Technical Reports Server (NTRS)

Woodward, R. Carey, Jr.; Scherb, Frank; Roesler, Fred L.

1994-01-01

In November and December 1988, we acquired 157 spectra of (S II) lambda 6731 emissions from the Io plasma torus with a Fabry-Perot interferometer at the McMath-Pierce Solar Telescope facility on Kitt Peak. A major goal of this experiment was to extend our earlier studies of intensity variations in the plasma torus. Our earlier analysis (F. L. Roesler, F. Scherb, and R. J. Oliversen, 1984, of (S III) lambda 9531 emission spectra acquired in April 1982 had shown that the intensity of torus emissions varied periodically with a period of 10.20 +/- 0.06 hr (1-sigma uncertainty level), slightly longer than Jupiter's System 3 rotational period of 9.925 hr. We present here an reanalysis of our 1982 data revealing, in addition to the 10.20-hr period, a clear secondary periodicity at 9.95 +/- 0.906 hr. By constrast, we show that our new (S II) lambda 6731 data have a single period of 10.14 +/- 0.03 hr. which is neither the System 3 period nor the proposed 'System 4' period of 10.224 hr.

Periodic intensity variations in sulfur emissions from the Io plasma torus

NASA Astrophysics Data System (ADS)

Woodward, R. Carey, Jr.; Scherb, Frank; Roesler, Fred L.; Oliversen, Ronald J.

1994-09-01

In November and December 1988, we acquired 157 spectra of (S II) lambda 6731 emissions from the Io plasma torus with a Fabry-Perot interferometer at the McMath-Pierce Solar Telescope facility on Kitt Peak. A major goal of this experiment was to extend our earlier studies of intensity variations in the plasma torus. Our earlier analysis (F. L. Roesler, F. Scherb, and R. J. Oliversen, 1984, of (S III) lambda 9531 emission spectra acquired in April 1982 had shown that the intensity of torus emissions varied periodically with a period of 10.20 +/- 0.06 hr (1-sigma uncertainty level), slightly longer than Jupiter's System 3 rotational period of 9.925 hr. We present here an reanalysis of our 1982 data revealing, in addition to the 10.20-hr period, a clear secondary periodicity at 9.95 +/- 0.906 hr. By constrast, we show that our new (S II) lambda 6731 data have a single period of 10.14 +/- 0.03 hr. which is neither the System 3 period nor the proposed 'System 4' period of 10.224 hr.

Advancing the Theory of Nuclear Reactions with Rare Isotopes. From the Laboratory to the Cosmos

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

Nunes, Filomena

2015-06-01

The mission of the Topical Collaboration on the Theory of Reactions for Unstable iSotopes (TORUS) was to develop new methods to advance nuclear reaction theory for unstable isotopes—particularly the (d,p) reaction in which a deuteron, composed of a proton and a neutron, transfers its neutron to an unstable nucleus. After benchmarking the state-of-the-art theories, the TORUS collaboration found that there were no exact methods to study (d,p) reactions involving heavy targets; the difficulty arising from the long-range nature of the well known, yet subtle, Coulomb force. To overcome this challenge, the TORUS collaboration developed a new theory where the complexitymore » of treating the long-range Coulomb interaction is shifted to the calculation of so-called form-factors. An efficient implementation for the computation of these form factors was a major achievement of the TORUS collaboration. All the new machinery developed are essential ingredients to analyse (d,p) reactions involving heavy nuclei relevant for astrophysics, energy production, and stockpile stewardship.« less

Spacecraft Electrostatic Radiation Shielding

NASA Technical Reports Server (NTRS)

2008-01-01

This project analyzed the feasibility of placing an electrostatic field around a spacecraft to provide a shield against radiation. The concept was originally proposed in the 1960s and tested on a spacecraft by the Soviet Union in the 1970s. Such tests and analyses showed that this concept is not only feasible but operational. The problem though is that most of this work was aimed at protection from 10- to 100-MeV radiation. We now appreciate that the real problem is 1- to 2-GeV radiation. So, the question is one of scaling, in both energy and size. Can electrostatic shielding be made to work at these high energy levels and can it protect an entire vehicle? After significant analysis and consideration, an electrostatic shield configuration was proposed. The selected architecture was a torus, charged to a high negative voltage, surrounding the vehicle, and a set of positively charged spheres. Van de Graaff generators were proposed as the mechanism to move charge from the vehicle to the torus to generate the fields necessary to protect the spacecraft. This design minimized complexity, residual charge, and structural forces and resolved several concerns raised during the internal critical review. But, it still is not clear if such a system is costeffective or feasible, even though several studies have indicated usefulness for radiation protection at energies lower than that of the galactic cosmic rays. Constructing such a system will require power supplies that can generate voltages 10 times that of the state of the art. Of more concern is the difficulty of maintaining the proper net charge on the entire structure and ensuring that its interaction with solar wind will not cause rapid discharge. Yet, if these concerns can be resolved, such a scheme may provide significant radiation shielding to future vehicles, without the excessive weight or complexity of other active shielding techniques.

A dynamic magnetic tension force as the cause of failed solar eruptions

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

Myers, Clayton E.; Yamada, Masaaki; Ji, Hantao

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has notmore » yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. In this paper, we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. Lastly, this magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.« less

A dynamic magnetic tension force as the cause of failed solar eruptions

DOE PAGES

Myers, Clayton E.; Yamada, Masaaki; Ji, Hantao; ...

2015-12-23

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun's corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has notmore » yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. In this paper, we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such 'failed torus' events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. Lastly, this magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.« less

Bifurcation of synchronous oscillations into torus in a system of two reciprocally inhibitory silicon neurons: experimental observation and modeling.

PubMed

Bondarenko, Vladimir E; Cymbalyuk, Gennady S; Patel, Girish; Deweerth, Stephen P; Calabrese, Ronald L

2004-12-01

Oscillatory activity in the central nervous system is associated with various functions, like motor control, memory formation, binding, and attention. Quasiperiodic oscillations are rarely discussed in the neurophysiological literature yet they may play a role in the nervous system both during normal function and disease. Here we use a physical system and a model to explore scenarios for how quasiperiodic oscillations might arise in neuronal networks. An oscillatory system of two mutually inhibitory neuronal units is a ubiquitous network module found in nervous systems and is called a half-center oscillator. Previously we created a half-center oscillator of two identical oscillatory silicon (analog Very Large Scale Integration) neurons and developed a mathematical model describing its dynamics. In the mathematical model, we have shown that an in-phase limit cycle becomes unstable through a subcritical torus bifurcation. However, the existence of this torus bifurcation in experimental silicon two-neuron system was not rigorously demonstrated or investigated. Here we demonstrate the torus predicted by the model for the silicon implementation of a half-center oscillator using complex time series analysis, including bifurcation diagrams, mapping techniques, correlation functions, amplitude spectra, and correlation dimensions, and we investigate how the properties of the quasiperiodic oscillations depend on the strengths of coupling between the silicon neurons. The potential advantages and disadvantages of quasiperiodic oscillations (torus) for biological neural systems and artificial neural networks are discussed.

[Kinetic theory and boundary conditions for highly inelastic spheres]. Quarterly progress report, April 1, 1993--June 30, 1993

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

Richman, M.

1993-12-31

In this quarter, a kinetic theory was employed to set up the boundary value problem for steady, fully developed, gravity-driven flows of identical, smooth, highly inelastic spheres down bumpy inclines. The solid fraction, mean velocity, and components of the full second moment of fluctuation velocity were treated as mean fields. In addition to the balance equations for mass and momentum, the balance of the full second moment of fluctuation velocity was treated as an equation that must be satisfied by the mean fields. However, in order to simplify the resulting boundary value problem, fluxes of second moments in its isotropicmore » piece only were retained. The constitutive relations for the stresses and collisional source of second moment depend explicitly on the second moment of fluctuation velocity, and the constitutive relation for the energy flux depends on gradients of granular temperature, solid fraction, and components of the second moment. The boundary conditions require that the flows are free of stress and energy flux at their tops, and that momentum and energy are balanced at the bumpy base. The details of the boundary value problem are provided. In the next quarter, a solution procedure will be developed, and it will be employed to obtain sample numerical solutions to the boundary value problem described here.« less

Effect of parameters on picosecond laser ablation of Cr12MoV cold work mold steel

NASA Astrophysics Data System (ADS)

Wu, Baoye; Liu, Peng; Zhang, Fei; Duan, Jun; Wang, Xizhao; Zeng, Xiaoyan

2018-01-01

Cr12MoV cold work mold steel, which is a difficult-to-machining material, is widely used in the mold and dye industry. A picosecond pulse Nd:YVO4 laser at 1064 nm was used to conduct the study. Effects of operation parameters (i.e., laser fluence, scanning speed, hatched space and number of scans) were studied on ablation depth and quality of Cr12MoV at the repetition rate of 20 MHz. The experimental results reveal that all the four parameters affect the ablation depth significantly. While the surface roughness depends mainly on laser fluence or scanning speed and secondarily on hatched space or number of scans. For laser fluence and scanning speed, three distinct surface morphologies were observed experiencing transition from flat (Ra < 1.40 μm) to bumpy (Ra = 1.40 - 2.40 μm) eventually to rough (Ra > 2.40 μm). However, for hatched space and number of scan, there is a small bumpy and rough zone or even no rough zone. Mechanisms including heat accumulation, plasma shielding and combustion reaction effects are proposed based on the ablation depth and processing morphology. By appropriate management of the laser fluence and scanning speed, high ablation depth with low surface roughness can be obtained at small hatched space and high number of scans.

Sunlit Io Atmospheric [O I] 6300 A and the Plasma Torus

NASA Technical Reports Server (NTRS)

Oliversen, Ronald J.; Scherb, Frank; Smyth, William H.; Freed, Melanie E.; Woodward, R. Carey, Jr.; Marcone, Maximus L.; Retherford, Kurt D.; Lupie, Olivia L.; Morgenthaler, Jeffrey P.; Fisher, Richard R. (Technical Monitor)

2001-01-01

A large database of sunlit Io [O I] 6300A emission, acquired over the period 1990-1999, with extensive coverage of Io orbital phase angle phi and System III longitude lambda(sub III), exhibits significant long-term and short-term variations in [O I] 6300A emission intensities. The long-term average intensity shows a clear dependence on lambda(sub III), which establishes conclusively that the emission is produced by the interaction between Io's atmosphere and the plasma torus. Two prominent average intensity maxima, 70 deg to 90 deg wide, are centered at lambda(sub III) about 130deg. and about 295 deg. A comparison of data from October 1998 with a three-dimensional plasma torus model, based upon electron impact excitation of atomic oxygen, suggests a basis for study of the torus interaction with Io's atmosphere. The observed short-term, erratic [O I] 6300A intensity variations fluctuate approximately 20% to 50% on time scale of tens of minutes with less frequent fluctuations of a factor of about 2. The most likely candidate to produce these fluctuations is a time-variable energy flux of field-aligned nonthermal electrons identified recently in Galileo PLS data. If true, the short-term [O I] intensity fluctuations may be related to variable field-aligned currents driven by inward and outward torus plasma transport and/or transient high-latitude, field-aligned potential drops. A correlation between the intensity and emission line width indicates molecular dissociation may contribute significantly to the [O I] 6300A emission. The nonthermal electron energy flux may produce O(1-D) by electron impact dissociation of SO2 and SO, with the excess energy going into excitation of O and its kinetic energy. The [O I] 6300A emission database establishes Io as a valuable probe of the torus, responding to local conditions at Io's position.

Does the obscured AGN fraction really depend on luminosity?

NASA Astrophysics Data System (ADS)

Sazonov, S.; Churazov, E.; Krivonos, R.

2015-12-01

We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ≲ 1042.5 erg s-1 (17-60 keV), and decreases to ≲60 per cent at L ≳ 1044 erg s-1. In terms of the half-opening angle θ of an obscuring torus, this implies that θ ≲ 30° in lower luminosity AGN, and θ ≳ 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/dΩ ∝ cos α, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle θ ˜ 30°.

Quantum field theory on toroidal topology: Algebraic structure and applications

NASA Astrophysics Data System (ADS)

Khanna, F. C.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Santana, A. E.

2014-05-01

The development of quantum theory on a torus has a long history, and can be traced back to the 1920s, with the attempts by Nordström, Kaluza and Klein to define a fourth spatial dimension with a finite size, being curved in the form of a torus, such that Einstein and Maxwell equations would be unified. Many developments were carried out considering cosmological problems in association with particle physics, leading to methods that are useful for areas of physics, in which size effects play an important role. This interest in finite size effect systems has been increasing rapidly over the last decades, due principally to experimental improvements. In this review, the foundations of compactified quantum field theory on a torus are presented in a unified way, in order to consider applications in particle and condensed matter physics. The theory on a torus ΓDd=(S1)d×RD-d is developed from a Lie-group representation and c*c*-algebra formalisms. As a first application, the quantum field theory at finite temperature, in its real- and imaginary-time versions, is addressed by focusing on its topological structure, the torus Γ41. The toroidal quantum-field theory provides the basis for a consistent approach of spontaneous symmetry breaking driven by both temperature and spatial boundaries. Then the superconductivity in films, wires and grains are analyzed, leading to some results that are comparable with experiments. The Casimir effect is studied taking the electromagnetic and Dirac fields on a torus. In this case, the method of analysis is based on a generalized Bogoliubov transformation, that separates the Green function into two parts: one is associated with the empty space-time, while the other describes the impact of compactification. This provides a natural procedure for calculating the renormalized energy-momentum tensor. Self interacting four-fermion systems, described by the Gross-Neveu and Nambu-Jona-Lasinio models, are considered. Then finite size effects on the hadronic phase structure are investigated, taking into account density and temperature. As a final application, effects of extra spatial dimensions are addressed, by developing a quantum electrodynamics in a five-dimensional space-time, where the fifth-dimension is compactified on a torus. The formalism, initially developed for particle physics, provides results compatible with other trials of probing the existence of extra-dimensions.

Titan's gas and plasma torus

NASA Technical Reports Server (NTRS)

Eviatar, A.; Podolak, M.

1983-01-01

The implications of the Voyager observations for a steady state model of a torus of hydrogen and nitrogen neutral gas and plasma are assessed. Constraints are placed on the nitrogen neutral density, the neutral hydrogen and nitrogen escape fluxes (from Titan), and the diffusion rate in terms of observed or inferred quantities. The results obtained are consistent with the Voyager observations.

Atomic force microscopy of torus-bearing pit membranes

Treesearch

Roland R. Dute; Thomas Elder

2011-01-01

Atomic force microscopy was used to compare the structures of dried, torus-bearing pit membranes from four woody species, three angiosperms and one gymnosperm. Tori of Osmanthus armatus are bipartite consisting of a pustular zone overlying parallel sets of microfibrils that form a peripheral corona. Microfibrils of the corona form radial spokes as they traverse the...

Ultraviolet emissions from the upper atmospheres of the planets

NASA Technical Reports Server (NTRS)

Moos, H. W.

1981-01-01

Some recent results on planetary upper atmospheres obtained by means of orbiting ultraviolet observatories are reviewed with emphasis on Jupiter and Io torus. Consideration is given to long-term variation in Jovian Ly alpha emission, UV polar auroras on Jupiter, and UV emission from the Io torus. Requirements for UV planetary astronomy are briefly discussed.

Numerical study of the Columbia high-beta device: Torus-II

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

Izzo, R.

1981-01-01

The ionization, heating and subsequent long-time-scale behavior of the helium plasma in the Columbia fusion device, Torus-II, is studied. The purpose of this work is to perform numerical simulations while maintaining a high level of interaction with experimentalists. The device is operated as a toroidal z-pinch to prepare the gas for heating. This ionization of helium is studied using a zero-dimensional, two-fluid code. It is essentially an energy balance calculation that follows the development of the various charge states of the helium and any impurities (primarily silicon and oxygen) that are present. The code is an atomic physics model ofmore » Torus-II. In addition to ionization, we include three-body and radiative recombination processes.« less

On the location of the Io plasma torus: Voyager 1 observations

NASA Astrophysics Data System (ADS)

Volwerk, Martin

2018-06-01

The Voyager 1 outbound ultraviolet observations of the Io plasma torus are used to determine the location of the ansae, to obtain a third viewing angle of this structure in the Jovian magnetosphere. At an angle of -114° with respect to the Sun-Jupiter line, or a Jovian local time of 04:30 LT, the Voyager 1 data deliver a distance of 5.74±0.10 RJ for the approaching and 5.83±0.15 RJ for the receding ansa. Various periodicities in the radial distance, brightness and width of the ansae are seen with respect to system III longitude and Io phase angle. The torus ribbon feature does not appear in all ansa scans.

New Spectral Model for Constraining Torus Covering Factors from Broadband X-Ray Spectra of Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Baloković, M.; Brightman, M.; Harrison, F. A.; Comastri, A.; Ricci, C.; Buchner, J.; Gandhi, P.; Farrah, D.; Stern, D.

2018-02-01

The basic unified model of active galactic nuclei (AGNs) invokes an anisotropic obscuring structure, usually referred to as a torus, to explain AGN obscuration as an angle-dependent effect. We present a new grid of X-ray spectral templates based on radiative transfer calculations in neutral gas in an approximately toroidal geometry, appropriate for CCD-resolution X-ray spectra (FWHM ≥ 130 eV). Fitting the templates to broadband X-ray spectra of AGNs provides constraints on two important geometrical parameters of the gas distribution around the supermassive black hole: the average column density and the covering factor. Compared to the currently available spectral templates, our model is more flexible, and capable of providing constraints on the main torus parameters in a wider range of AGNs. We demonstrate the application of this model using hard X-ray spectra from NuSTAR (3–79 keV) for four AGNs covering a variety of classifications: 3C 390.3, NGC 2110, IC 5063, and NGC 7582. This small set of examples was chosen to illustrate the range of possible torus configurations, from disk-like to sphere-like geometries with column densities below, as well as above, the Compton-thick threshold. This diversity of torus properties challenges the simple assumption of a standard geometrically and optically thick toroidal structure commonly invoked in the basic form of the unified model of AGNs. Finding broad consistency between our constraints and those from infrared modeling, we discuss how the approach from the X-ray band complements similar measurements of AGN structures at other wavelengths.

Io plasma torus ion composition: Voyager, Galileo, and Cassini

NASA Astrophysics Data System (ADS)

Nerney, Edward G.; Bagenal, Fran; Steffl, Andrew J.

2017-01-01

The Io torus produces ultraviolet emissions diagnostic of plasma conditions. We revisit data sets obtained by the Voyager 1, Galileo, and Cassini missions at Jupiter. With the latest version (8.0) of the CHIANTI atomic database we analyze UV spectra to determine ion composition. We compare ion composition obtained from observations from these three missions with a theoretical model of the physical chemistry of the torus by Delamere et al. (2005). We find ion abundances from the Voyager data similar to the Cassini epoch, consistent with the dissociation and ionization of SO2, but with a slightly higher average ionization state for sulfur, consistent with the higher electron temperature measured by Voyager. This reanalysis of the Voyager data produces a much lower oxygen:sulfur ratio than earlier analysis by Shemansky (1988), which was also reported by Bagenal (1994). We derive fractional ion compositions in the center of the torus to be S+/Ne 5%, S++/Ne 20%, S+++/Ne 5%, O+/Ne 20%, O++/Ne 3%, and Σ(On+)/Σ(Sn+) 0.8, leaving about 10-15% of the charge as protons. The radial profile of ion composition indicates a slightly higher average ionization state, a modest loss of sulfur relative to oxygen, and Σ(On+)/Σ(Sn+) 1.2 at about 8 RJ, beyond which the composition is basically frozen in. The Galileo observations of UV emissions from the torus suggest that the composition in June 1996 may have comprised a lower abundance of oxygen than usual, consistent with observations made at the same time by the EUVE satellite.

Balancing the spatial demands of the developing dentition with the mechanical demands of the catarrhine mandibular symphysis

PubMed Central

Cobb, Samuel N; Panagiotopoulou, Olga

2011-01-01

The superior transverse torus of the catarrhine mandible has been shown to effectively reduce bending at the symphysis during unilateral postcanine biting. While the adult superior transverse torus contains trabecular bone, the juvenile one is almost entirely filled by developing permanent incisors until their eruption. This study uses finite elements analysis (FEA) to investigate whether the presence of developing incisors in the juvenile symphysis increases strains on the superior transverse torus. Two FE models of a juvenile Macaca fascicularis mandible were created: one included all the developing teeth; the second was modified to remove the incisor tooth crypts by filling them with trabecular bone. The models were loaded identically to simulate static physiological unilateral biting on dp4 and strain magnitudes, patterns and distributions of the two FE models were compared. The FEA results show a notable increase in strain magnitudes by up to 40% when the developing incisors are present. The results indicate that, in order to maintain the same symphyseal strain magnitudes during chewing, the presence of the incisors in the symphysis necessitates a larger superior transverse torus in the juvenile than would be required if the superior transverse torus did not house the developing incisors. These results highlight the adaptational balance of the symphyseal morphology throughout ontogeny between biomechanics and the spatial demands of the developing dentition. Based on the findings we therefore propose that the spatial requirements of the developing incisors during ontogeny can act as a constraint on the functional adaptation and subsequent adult morphology observed in the catarrhine mandibular symphysis. PMID:21158857

A New Cross-By-Pass-Torus Architecture Based on CBP-Mesh and Torus Interconnection for On-Chip Communication.

PubMed

Gulzari, Usman Ali; Sajid, Muhammad; Anjum, Sheraz; Agha, Shahrukh; Torres, Frank Sill

2016-01-01

A Mesh topology is one of the most promising architecture due to its regular and simple structure for on-chip communication. Performance of mesh topology degraded greatly by increasing the network size due to small bisection width and large network diameter. In order to overcome this limitation, many researchers presented modified Mesh design by adding some extra links to improve its performance in terms of network latency and power consumption. The Cross-By-Pass-Mesh was presented by us as an improved version of Mesh topology by intelligent addition of extra links. This paper presents an efficient topology named Cross-By-Pass-Torus for further increase in the performance of the Cross-By-Pass-Mesh topology. The proposed design merges the best features of the Cross-By-Pass-Mesh and Torus, to reduce the network diameter, minimize the average number of hops between nodes, increase the bisection width and to enhance the overall performance of the network. In this paper, the architectural design of the topology is presented and analyzed against similar kind of 2D topologies in terms of average latency, throughput and power consumption. In order to certify the actual behavior of proposed topology, the synthetic traffic trace and five different real embedded application workloads are applied to the proposed as well as other competitor network topologies. The simulation results indicate that Cross-By-Pass-Torus is an efficient candidate among its predecessor's and competitor topologies due to its less average latency and increased throughput at a slight cost in network power and energy for on-chip communication.

Effective Induction Heating around Strongly Magnetized Stars

NASA Astrophysics Data System (ADS)

Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.; Noack, L.; Lüftinger, T.; Zaitsev, V. V.; Lammer, H.

2018-05-01

Planets that are embedded in the changing magnetic fields of their host stars can experience significant induction heating in their interiors caused by the planet’s orbital motion. For induction heating to be substantial, the planetary orbit has to be inclined with respect to the stellar rotation and dipole axes. Using WX UMa, for which the rotation and magnetic axes are aligned, as an example, we show that for close-in planets on inclined orbits, induction heating can be stronger than the tidal heating occurring inside Jupiter’s satellite Io; namely, it can generate a surface heat flux exceeding 2 W m‑2. An internal heating source of such magnitude can lead to extreme volcanic activity on the planet’s surface, possibly also to internal local magma oceans, and to the formation of a plasma torus around the star aligned with the planetary orbit. A strongly volcanically active planet would eject into space mostly SO2, which would then dissociate into oxygen and sulphur atoms. Young planets would also eject CO2. Oxygen would therefore be the major component of the torus. If the O I column density of the torus exceeds ≈1012 cm‑2, the torus could be revealed by detecting absorption signatures at the position of the strong far-ultraviolet O I triplet at about 1304 Å. We estimate that this condition is satisfied if the O I atoms in the torus escape the system at a velocity smaller than 1–10 km s‑1. These estimates are valid also for a tidally heated planet.

An Investigation of the Facilitative and Inhibitory Variables Impacting Breast Health Practices in Low-Socioeconomic Status Black Women of African American and Caribbean Descent

DTIC Science & Technology

2003-10-01

Honestly, it’~> been a very difficult tim~p here ... pancreatic cancer is a bumpy ride of lingering pain and suffering. I hope every day that my time...TELEPHONE NUMBER (include area code) 14. ABSTRACT Black women of low-socioeconomic status (SES) demonstrate a high incidence of breast cancer ...mortality associated with late-state diagnosis. Breast cancer screening, including mammography, breast self-examination, and clinical breast

Ground-based observations of the Io torus during Voyager 1 encounter - Indications of enhanced plasma injection and transport

NASA Technical Reports Server (NTRS)

Eviatar, A.; Mekler, Y.; Brosch, N.; Mazah, T.

1981-01-01

Ground-based spectroscopic observations of the cold Io torus made before, during and after the Voyager 1 encounter are compared to the published spacecraft data. During the encounter itself neither sodium nor sulfur emissions were detected. The implications of this finding for the injection and transport of plasma are assessed.

Application of an Externally Applied Rotating Magnetic Field for Control of MHD Relaxation Phenomena in the HIST Spherical Torus Device

NASA Astrophysics Data System (ADS)

Kikuchi, Yusuke; Yoshikawa, Tatsuya; Nishioka, Tsutomu; Hashimoto, Shotaro; Fukumoto, Naoyuki; Nagata, Masayoshi

Application of an externally applied rotating magnetic field (RMF) for control of MHD relaxation phenomena driven by a coaxial helicity injection has been proposed in the HIST spherical torus device. In this letter, the plasma responses to the RMF evaluated by magnetic fields inside the plasma in HIST are shown.

Multipass optical device and process for gas and analyte determination

DOEpatents

Bernacki, Bruce E [Kennewick, WA

2011-01-25

A torus multipass optical device and method are described that provide for trace level determination of gases and gas-phase analytes. The torus device includes an optical cavity defined by at least one ring mirror. The mirror delivers optical power in at least a radial and axial direction and propagates light in a multipass optical path of a predefined path length.

Iogenic Plasma and its Rotation-Driven Transport in Jupiter's Magnetosphere

NASA Technical Reports Server (NTRS)

Smyth, William H.

2001-01-01

Model calculations are reported for the Iogenic plasma source created by atomic oxygen and sulfur above Io's exobase in the corona and extended clouds (Outer Region). On a circumplanetary scale, two-dimensional distributions produced by integrating the proper three dimensional rate information for electron impact and charge exchange processes along the magnetic field lines are presented for the pickup ion rates, the net-mass and total-mass loading rates, the mass per unit magnetic flux rate, the pickup conductivity, the radial pickup current, and the net-energy loading rate for the plasma torus. All of the two-dimensional distributions are highly peaked at Io's location and hence highly asymmetric about Jupiter. The Iogenic plasma source is also calculated on a much smaller near-Io scale to investigate the structure of the highly peak rates centered about lo's instantaneous location. The Iogenic plasma source for the Inner Region (pickup rates produced below Io's exobase) is, however, expected to be the dominant source near lo for the formation of the plasma torus ribbon and to be a comparable source, if not a larger contributor, to the energy budget of the plasma torus, so as to provide the necessary power to sustain the plasma torus radiative loss rate.

The Phobos neutral and ionized torus

NASA Astrophysics Data System (ADS)

Poppe, A. R.; Curry, S. M.; Fatemi, S.

2016-05-01

Charged particle sputtering, micrometeoroid impact vaporization, and photon-stimulated desorption are fundamental processes operating at airless surfaces throughout the solar system. At larger bodies, such as Earth's Moon and several of the outer planet moons, these processes generate tenuous surface-bound exospheres that have been observed by a variety of methods. Phobos and Deimos, in contrast, are too gravitationally weak to keep ejected neutrals bound and, thus, are suspected to generate neutral tori in orbit around Mars. While these tori have not yet been detected, the distribution and density of both the neutral and ionized components are of fundamental interest. We combine a neutral Monte Carlo model and a hybrid plasma model to investigate both the neutral and ionized components of the Phobos torus. We show that the spatial distribution of the neutral torus is highly dependent on each individual species (due to ionization rates that span nearly 4 orders of magnitude) and on the location of Phobos with respect to Mars. Additionally, we present the flux distribution of torus pickup ions throughout the Martian system and estimate typical pickup ion fluxes. We find that the predicted pickup ion fluxes are too low to perturb the ambient plasma, consistent with previous null detections by spacecraft around Mars.

Spatially Resolved HCN Absorption Features in the Circumnuclear Region of NGC 1052

NASA Astrophysics Data System (ADS)

Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin; Lee, Sang-Sung; Byun, Do-Young; Kameno, Seiji; Yeom, Jae-Hwan; Jung, Dong-Kyu; Kim, Hyo-Ryoung; Hwang, Ju-Yeon

2016-10-01

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s-1, redshifted by 149 and 212 km s-1 with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 1015-1016 cm-2, assuming an excitation temperature of 100-230 K. The absorption features show high optical depth localized on the receding jet side, where the free-free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.

Towards a fourth spatial dimension of brain activity.

PubMed

Tozzi, Arturo; Peters, James F

2016-06-01

Current advances in neurosciences deal with the functional architecture of the central nervous system, paving the way for general theories that improve our understanding of brain activity. From topology, a strong concept comes into play in understanding brain functions, namely, the 4D space of a "hypersphere's torus", undetectable by observers living in a 3D world. The torus may be compared with a video game with biplanes in aerial combat: when a biplane flies off one edge of gaming display, it does not crash but rather it comes back from the opposite edge of the screen. Our thoughts exhibit similar behaviour, i.e. the unique ability to connect past, present and future events in a single, coherent picture as if we were allowed to watch the three screens of past-present-future "glued" together in a mental kaleidoscope. Here we hypothesize that brain functions are embedded in a imperceptible fourth spatial dimension and propose a method to empirically assess its presence. Neuroimaging fMRI series can be evaluated, looking for the topological hallmark of the presence of a fourth dimension. Indeed, there is a typical feature which reveal the existence of a functional hypersphere: the simultaneous activation of areas opposite each other on the 3D cortical surface. Our suggestion-substantiated by recent findings-that brain activity takes place on a closed, donut-like trajectory helps to solve long-standing mysteries concerning our psychological activities, such as mind-wandering, memory retrieval, consciousness and dreaming state.

TORUS: Radiation transport and hydrodynamics code

NASA Astrophysics Data System (ADS)

Harries, Tim

2014-04-01

TORUS is a flexible radiation transfer and radiation-hydrodynamics code. The code has a basic infrastructure that includes the AMR mesh scheme that is used by several physics modules including atomic line transfer in a moving medium, molecular line transfer, photoionization, radiation hydrodynamics and radiative equilibrium. TORUS is useful for a variety of problems, including magnetospheric accretion onto T Tauri stars, spiral nebulae around Wolf-Rayet stars, discs around Herbig AeBe stars, structured winds of O supergiants and Raman-scattered line formation in symbiotic binaries, and dust emission and molecular line formation in star forming clusters. The code is written in Fortran 2003 and is compiled using a standard Gnu makefile. The code is parallelized using both MPI and OMP, and can use these parallel sections either separately or in a hybrid mode.

Long-term stability of the Io high-temperature plasma torus

NASA Technical Reports Server (NTRS)

Moos, H. W.; Skinner, T. E.; Durrance, S. T.; Feldman, P. D.; Festou, M. C.

1985-01-01

The short wavelength camera of the International Ultraviolet Explorer satellite was used to measure S II 1256, S III 1199, semiforbidden S III 1729, and semiforbidden S IV 1406 emission from the high-temperature region of the Io plasma torus. Observations over a period of five years (1979-1984) indicate that the Io plasma parameters have relatively small variations, particularly in the case of the mixing ratio for the dominant constituent S(++), and electron temperature. A simple three-dimensional model of the plasma torus was used to obtain the ion mixing ratios and the plasma density for each observation. The results are compared with Voyager 1 data for mixing ratio (ion density divided by electron density); ionization balance; and plasma density. The results of the comparison are discussed in detail.

Five-dimensional gauge theory and compactification on a torus

NASA Astrophysics Data System (ADS)

Haghighat, Babak; Vandoren, Stefan

2011-09-01

We study five-dimensional minimally supersymmetric gauge theory compactified on a torus down to three dimensions, and its embedding into string/M-theory using geometric engineering. The moduli space on the Coulomb branch is hyperkähler equipped with a metric with modular transformation properties. We determine the one-loop corrections to the metric and show that they can be interpreted as worldsheet and D1-brane instantons in type IIB string theory. Furthermore, we analyze instanton corrections coming from the solitonic BPS magnetic string wrapped over the torus. In particular, we show how to compute the path-integral for the zero-modes from the partition function of the M5 brane, or, using a 2d/4d correspondence, from the partition function of N=4 SYM theory on a Hirzebruch surface.

Intermittency and solitons in the driven dissipative nonlinear Schroedinger equation

NASA Technical Reports Server (NTRS)

Moon, H. T.; Goldman, M. V.

1984-01-01

The cubic nonlinear Schroedinger equation, in the presence of driving and Landau damping, is studied numerically. As the pump intensity is increased, the system exhibits a transition from intermittency to a two-torus to chaos. The laminar phase of the intermittency is also a two-torus motion which corresponds in physical space to two identical solitons of amplitude determined by a power-balance equation.

Sur le spectre du laplacien des fibrés en tores qui s'effondrent

NASA Astrophysics Data System (ADS)

Jammes, Pierre

2005-06-01

We study the small eigenvalues of the Hodge Laplacian on collaping torus bundles with bounded curvature. In the first part of this dissertation, we consider examples of bundles on S^1 and T^2 with homogeneous structure. In the second part, we give a lower bound of the first non-zero eigenvalue of the 1-form Laplacian on principal torus bundles.

BPS States, Torus Links and Wild Character Varieties

NASA Astrophysics Data System (ADS)

Diaconescu, Duiliu-Emanuel; Donagi, Ron; Pantev, Tony

2018-02-01

A string theoretic framework is constructed relating the cohomology of wild character varieties to refined stable pair theory and torus link invariants. Explicit conjectural formulas are derived for wild character varieties with a unique irregular point on the projective line. For this case, this leads to a conjectural colored generalization of existing results of Hausel, Mereb and Wong as well as Shende, Treumann and Zaslow.

Astronomical studies of the major planets, natural satellites and asteroids using the 2.24 m telescope

NASA Technical Reports Server (NTRS)

Jefferies, J. T.

1982-01-01

Ground based detection of east-west asymmetries in the Jovian torus, three dimensional models of the plasma conditions in the Jovian torus, rotational variations in methane band images of Neptune, Io's rapid flickering, thermophysical models, the diameters and albedos of the satellites of Uranus from radiometric observations, the diameters of Pluto and Triton, standard stars are discussed.

Morphology and identification of fly eggs: application in forensic entomology.

PubMed

Sanit, S; Sribanditmongkol, P; Sukontason, K L; Moophayak, K; Klong-Klaew, T; Yasanga, T; Sukontason, K

2013-06-01

Fly eggs found in corpses can be used as entomological evidence in forensic investigation. This study aims to investigate the morphology of forensically important fly eggs. Eggs of Chrysomya rufifacies, Chrysomya megacephala, Chrysomya pinguis, Chrysomya nigripes, Hypopygiopsis tumrasvini, Lucilia cuprina, Lucilia porphyrina and Musca domestica were examined using 1% potassium permanganate solution for 1 min. Morphometric analysis revealed that the mean length of Hy. tumrasvini (1.63 mm) and C. pinguis (1.65 mm) eggs was the longest, followed by that of L. porphyrina (1.45 mm), C. rufifacies (1.34 mm). The egg length, width of median area and darkness staining of hatching pleats were distinctive features. Four categories of median area were proposed, based on width; (1) distinctly wide (Megaselia scalaris, Synthesiomyia nudiseta); (2) wide (C. nigripes, M. domestica); (3) slightly widening (Hy. tumrasvini, L. cuprina, L. porphyrina); and (4) narrow (C. rufifacies, C. albiceps, C. megacephala, C. pinguis). Four species were examined using SEM, i.e., C. megacephala, C. pinguis, Hy. tumrasvini and L. porphyrina. The eggs of C. megacephala demonstrated swollen hatching pleats. Inside, the hexagon of the chorion appeared as a sponging bumpy feature. The egg of C. pinguis was similar to C. megacephala, except for the sponging bumpy feature on the outer surface of the hatching pleats. Regarding Hy. tumrasvini and L. porphyrina, their island structure was apparent at the inner surface of the upright hatching pleats. The key for identifying these eggs together with other reported species in Thailand has been updated.

Hints of a rotating spiral structure in the innermost regions around IRC +10216

PubMed Central

Quintana-Lacaci, G.; Cernicharo, J.; Agúndez, M.; Prieto, L. Velilla; Castro-Carrizo, A.; Marcelino, N.; Cabezas, C.; Peña, I.; Alonso, J.L.; Zúñiga, J.; Requena, A.; Bastida, A.; Kalugina, Y.; Lique, F.; Guélin, M.

2016-01-01

The Atacama Large Millimeter/submillimeter Array (ALMA) is allowing us to study the innermost regions of the circumstellar envelopes of evolved stars with un-precedented precision and sensitivity. Key processes in the ejection of matter and dust from these objects occur in their inner zones. In this work, we present sub-arcsecond interferometric maps of transitions of metal-bearing molecules towards the prototypical C-rich evolved star IRC +10216. While Al-bearing molecules seem to be present as a roughly spherical shell, the molecular emission from the salts NaCl and KCl presents an elongation in the inner regions, with a central minimum. In order to accurately analyze the emission from the NaCl rotational lines, we present new calculations of the collisional rates for this molecule based on new spectroscopic constants. The most plausible interpretation for the spatial distribution of the salts is a spiral with a NaCl mass of 0.08M☉. Alternatively, a torus of gas and dust would result in similar structures as those observed. From the torus scenario we derive a mass of ~ 1.1 × 10−4M☉. In both cases, the spiral and the torus, the NaCl structure presents an inner minimum of 27 AU. In the case of the torus, the outer radius is 73 AU. The kinematics of both the spiral and the torus suggests that they are slowly expanding and rotating. Alternative explanations for the presence of the elongation are explored. The presence of these features only in KCl and NaCl might be a result of their comparatively high dipole moment with respect to the Al-bearing species. PMID:26997665

Parsec-Scale Accretion and Winds Irradiated by a Quasar

NASA Technical Reports Server (NTRS)

Dorodnitsyn, A.; Kallman, T.; Proga, D.

2016-01-01

We present numerical simulations of properties of a parsec-scale torus exposed to illumination by the central black hole in an active galactic nucleus (AGN). Our physical model allows to investigate the balance between the formation of winds and accretion simultaneously. Radiation-driven winds are allowed by taking into account radiation pressure due to UV and IR radiation along with X-ray heating and dust sublimation. Accretion is allowed through angular momentum transport and the solution of the equations of radiative, viscous radiation hydrodynamics. Our methods adopt flux-limited diffusion radiation hydrodynamics for the dusty, infrared pressure driven part of the flow, along with X-ray heating and cooling. Angular momentum transport in the accreting part of the flow is modeled using effective viscosity. Our results demonstrate that radiation pressure on dust can play an important role in shaping AGN obscuration. For example, when the luminosity illuminating the torus exceeds L greater than 0.01 L(sub Edd), where L(sub Edd) is the Eddington luminosity, we find no episodes of sustained disk accretion because radiation pressure does not allow a disk to form. Despite the absence of the disk accretion, the flow of gas to smaller radii still proceeds at a rate 10(exp -4)-10(exp -1)M dot yr(exp -1) through the capturing of the gas from the hot evaporative flow, thus providing a mechanism to deliver gas from a radiation-pressure dominated torus to the inner accretion disk. As L L(sub edd) increases, larger radiation input leads to larger torus aspect ratios and increased obscuration of the central black hole. We also find the important role of the X-ray heated gas in shaping the obscuring torus.

Cassini UVIS Observations of the Io Plasma Torus. 3; Observations of Temporal and Azimuthal Variability

NASA Technical Reports Server (NTRS)

Steffl, A. J.; Delamere, P. A.; Bagenal, F.

2006-01-01

In this third paper in a series presenting observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near sinusoidal variations in ion composition as a functions of azimuthal position. The azimuthal variation in composition is such that the mixing ratio of S II us strongly correlated with the mixing ratio of S III and the equatorial electron density and strongly anti-correlated with the mixing ratios of both S IV and O II and the equatorial electron temperature. Surprisingly, the azimuthal variation in ion composition is observed to have a period of 10.07 h -- 1.5% longer than the System III rotation period of Jupiter, yet 1.3% shorter than the System UV period defined by [Brown, M. E., 1995. J. Geophys. Res. 100, 21683-21696]. Although the amplitude of the azimuthal variation of S III and O II remained in the range of 2-5%, the amplitude of the S II and S IV compositional variation ranged between 5 and 25% during the UVIS observations. Furthermore, the amplitude of the azimuthal variations of S II and S IV appears to be modulated by its location in System III longitude, such that when the region of maximum S II mixing ration (minimum S IV mixing ratio) is aligned with a System III longitude of 200 deg +/-, the amplitude is a factor of 4 greater than when the variation is anti-aligned. This behavior can explain numerous, often apparently contradictory, observations of variations in the properties of the Io plasma torus with the System III and System IV coordinate systems.

Composite fermions on a torus

NASA Astrophysics Data System (ADS)

Pu, Songyang; Wu, Ying-Hai; Jain, J. K.

2017-11-01

We achieve an explicit construction of the lowest Landau level (LLL) projected wave functions for composite fermions in the periodic (torus) geometry. To this end, we first demonstrate how the vortex attachment of the composite fermion (CF) theory can be accomplished in the torus geometry to produce the "unprojected" wave functions satisfying the correct (quasi)periodic boundary conditions. We then consider two methods for projecting these wave functions into the LLL. The direct projection produces valid wave functions but can be implemented only for very small systems. The more powerful and more useful projection method of Jain and Kamilla fails in the torus geometry because it does not preserve the periodic boundary conditions and thus takes us out of the original Hilbert space. We have succeeded in constructing a modified projection method that is consistent with both the periodic boundary conditions and the general structure of the CF theory. This method is valid for a large class of states of composite fermions, called "proper states," which includes the incompressible ground states at electron filling factors ν =n/2 p n +1 , their charged and neutral excitations, and also the quasidegenerate ground states at arbitrary filling factors of the form ν =ν/*2pν*+1 , where n and p are integers and ν* is the CF filling factor. Comparison with exact results known for small systems for the ground and excited states at filling factors ν =1 /3 , 2/5, and 3/7 demonstrates our LLL-projected wave functions to be extremely accurate representations of the actual Coulomb eigenstates. Our construction enables the study of large systems of composite fermions on the torus, thereby opening the possibility of investigating numerous interesting questions and phenomena.

Io's Sodium Clouds and Plasma Torus: Three Quiet Apparitions

NASA Astrophysics Data System (ADS)

Wilson, Jody; Mendillo, M.; Baumgardner, J.

2007-10-01

Ground-based observations of Io's sodium clouds from February 2005 to June 2007 indicate that Io was in an unusually quiet state of atmospheric escape. Simultaneous observations of the sulfur-ion plasma torus in that same period indicate that the torus has been gradually dimming, which is also consistent with below-average atmospheric escape rates from Io. The S+ torus was essentially undetectable in May 2007. Our goal in this 3-year project was to compare variability in the clouds and torus with observations of Io's volcanic infrared ``hot spots'' (e.g., Marchis et al. 2005) in order to track the flow of mass from Io's volcanoes into Jupiter's magnetosphere. Of particular interest was the 18-month cycle of Io's large volcano Loki (Rathbun et al. 2002, Mendillo et al. 2004), however it seems that Loki has settled into an unusually long-term quiescent state (Rathbun and Spencer, 2006). Thus, although we have been unable to monitor the month-to-month effects of the Loki cycle, we nonetheless have indirect evidence for Loki's long-term effects on Io's atmosphere and Jupiter's magnetosphere by observing their weak states when Loki is not actively contributing. This research is funded in part by NASA's Planetary Astronomy Program. Marchis et al., Keck AO survey of Io global volcanic activity between 2 and 5 microns, Icarus, 176, 96-122, 2005. Mendillo et al., Io's volcanic control of Jupiter's extended neutral clouds, Icarus, 170, 430-442, 2004. Rathbun, J.A. et al., Loki, Io: A periodic volcano, Geophysical Research Letters, 29, Issue 10, pp. 84-1, 2002. Rathbun, J.A. and J.R. Spencer, Loki, Io: New ground-based observations and a model describing the change from periodic overturn, Geophysical Research Letters, 33, Issue 17, 2006.

Hints of a rotating spiral structure in the innermost regions around IRC +10216.

PubMed

Quintana-Lacaci, G; Cernicharo, J; Agúndez, M; Prieto, L Velilla; Castro-Carrizo, A; Marcelino, N; Cabezas, C; Peña, I; Alonso, J L; Zúñiga, J; Requena, A; Bastida, A; Kalugina, Y; Lique, F; Guélin, M

2016-02-20

The Atacama Large Millimeter/submillimeter Array (ALMA) is allowing us to study the innermost regions of the circumstellar envelopes of evolved stars with un-precedented precision and sensitivity. Key processes in the ejection of matter and dust from these objects occur in their inner zones. In this work, we present sub-arcsecond interferometric maps of transitions of metal-bearing molecules towards the prototypical C-rich evolved star IRC +10216. While Al-bearing molecules seem to be present as a roughly spherical shell, the molecular emission from the salts NaCl and KCl presents an elongation in the inner regions, with a central minimum. In order to accurately analyze the emission from the NaCl rotational lines, we present new calculations of the collisional rates for this molecule based on new spectroscopic constants. The most plausible interpretation for the spatial distribution of the salts is a spiral with a NaCl mass of 0.08 M ☉ . Alternatively, a torus of gas and dust would result in similar structures as those observed. From the torus scenario we derive a mass of ~ 1.1 × 10 -4 M ☉ . In both cases, the spiral and the torus, the NaCl structure presents an inner minimum of 27 AU. In the case of the torus, the outer radius is 73 AU. The kinematics of both the spiral and the torus suggests that they are slowly expanding and rotating. Alternative explanations for the presence of the elongation are explored. The presence of these features only in KCl and NaCl might be a result of their comparatively high dipole moment with respect to the Al-bearing species.

A Deep Herschel/PACS Observation of CO(40-39) in NGC 1068: A Search for the Molecular Torus

NASA Astrophysics Data System (ADS)

Janssen, A. W.; Bruderer, S.; Sturm, E.; Contursi, A.; Davies, R.; Hailey-Dunsheath, S.; Poglitsch, A.; Genzel, R.; Graciá-Carpio, J.; Lutz, D.; Tacconi, L.; Fischer, J.; González-Alfonso, E.; Sternberg, A.; Veilleux, S.; Verma, A.; Burtscher, L.

2015-10-01

Emission from high-J CO lines in galaxies has long been proposed as a tracer of X-ray dominated regions (XDRs) produced by active galactic nuclei (AGNs). Of particular interest is the question of whether the obscuring torus, which is required by AGN unification models, can be observed via high-J CO cooling lines. Here we report on the analysis of a deep Herschel/PACS observation of an extremely high-J CO transition (40-39) in the Seyfert 2 galaxy NGC 1068. The line was not detected, with a derived 3σ upper limit of 2× {10}-17 {{W}} {{{m}}}-2. We apply an XDR model in order to investigate whether the upper limit constrains the properties of a molecular torus in NGC 1068. The XDR model predicts the CO spectral line energy distributions for various gas densities and illuminating X-ray fluxes. In our model, the CO(40-39) upper limit is matched by gas with densities of ˜ {10}6-{10}7 {{cm}}-3, located at 1.6-5 pc from the AGN, with column densities of at least {10}25 {{cm}}-2. At such high column densities, however, dust absorbs most of the CO(40-39) line emission at λ =65.69 μ {{m}}. Therefore, even if NGC 1068 has a molecular torus that radiates in the CO(40-39) line, the dust can attenuate the line emission to below the PACS detection limit. The upper limit is thus consistent with the existence of a molecular torus in NGC 1068. In general, we expect that the CO(40-39) is observable in only a few AGN nuclei (if at all), because of the required high gas column density, and absorption by dust.

Modeling Ultraviolet Emissions Near Io

NASA Technical Reports Server (NTRS)

Linker, Jon A.

2000-01-01

In this report, we describe work awarded to Science Applications International Corporation, for the period 6/l/99 to 5/31/00. During this time period, we have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the role this interaction plays in producing ultraviolet (UV) emissions from neutral oxygen and sulfur. Io, the innermost of Jupiter's Galilean satellites, plays a unique role in the jovian magnetosphere. Neutral material that escapes from Io is ionized to form the lo torus, a dense, heavy-ion plasma that corotates with Jupiter and interacts with Io. Io supplies not only the torus, but is a major source of plasma for the entire magnetosphere. Ionization and charge-exchange of neutrals near lo strongly influences the plasma interaction, and Io's neutral atmosphere plays an important role in the generation of currents that couple Io to Jupiter. There have been no in situ measurements of the neutral density near Io, but remote observations of neutrals near lo have been performed for many years. Recent observations from the Hubble Space Telescope (HST) have shown detailed structure in UV emissions from neutral species near Io. Electron-impact of the neutrals by the Io torus plasma is the primary mechanism responsible for exciting these emissions. Previously, we have modeled the Io plasma environment using three-dimensional magnetohydrodynamic (MHD) simulations, and we have shown that the interaction between Io and the plasma torus plays an important role in producing the morphology of the observed emissions. In the past year, we have extended these studies to use both UV observations and Galileo particle and field measurements to investigate the Io interaction.

X-Ray Absorption, Nuclear Infrared Emission, and Dust Covering Factors of AGNs: Testing Unification Schemes

NASA Astrophysics Data System (ADS)

Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X.; Asensio Ramos, A.; Watson, M. G.; Blain, A.; Caccianiga, A.; Ballo, L.; Braito, V.; Ramos Almeida, C.

2016-03-01

We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2-10 keV luminosities between 1042 and 1046 erg s-1, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1-20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f2 than type 1 AGNs. Nevertheless, ˜20% of type 1 AGNs have tori with large covering factors, while ˜23%-28% of type 2 AGNs have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f2 increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f2 determine the optical appearance of an AGN and control the shape of the rest-frame ˜1-20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.

Observational evidence of torus instability as trigger mechanism for coronal mass ejections: The 2011 August 4 filament eruption

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

Zuccarello, F. P.; Poedts, S.; Seaton, D. B.

Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days—even weeks—which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to reveal what mechanism causes (or triggers) these solar eruptions. Validating these models through observations represents a fundamental step in our understanding of solar eruptions. We present an analysis of the observation of a filament eruption that agrees with the torus instability model. This model predicts that a magneticmore » flux rope embedded in an ambient field undergoes an eruption when the axis of the flux rope reaches a critical height that depends on the topology of the ambient field. We use the two vantage points of the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory to reconstruct the three-dimensional shape of the filament, to follow its morphological evolution, and to determine its height just before eruption. The magnetograms acquired by SDO/Helioseismic and Magnetic Imager are used to infer the topology of the ambient field and to derive the critical height for the onset of the torus instability. Our analysis shows that the torus instability is the trigger of the eruption. We also find that some pre-eruptive processes, such as magnetic reconnection during the observed flares and flux cancellation at the neutral line, facilitated the eruption by bringing the filament to a region where the magnetic field was more vulnerable to the torus instability.« less

EXTERNAL COMPTON SCATTERING IN BLAZAR JETS AND THE LOCATION OF THE GAMMA-RAY EMITTING REGION

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

Finke, Justin D., E-mail: justin.finke@nrl.navy.mil

2016-10-20

I study the location of the γ -ray emission in blazar jets by creating a Compton-scattering approximation that is valid for all anisotropic radiation fields in the Thomson through Klein–Nishina regimes, is highly accurate, and can speed up numerical calculations by up to a factor of ∼10. I apply this approximation to synchrotron self-Compton, external Compton scattering of photons from the accretion disk, broad line region (BLR), and dust torus. I use a stratified BLR model and include detailed Compton-scattering calculations of a spherical and flattened BLR. I create two dust torus models, one where the torus is an annulusmore » and one where it is an extended disk. I present detailed calculations of the photoabsorption optical depth using my detailed BLR and dust torus models, including the full angle dependence. I apply these calculations to the emission from a relativistically moving blob traveling through these radiation fields. The ratio of γ -ray to optical flux produces a predictable pattern that could help locate the γ -ray emission region. I show that the bright flare from 3C 454.3 in 2010 November detected by the Fermi Large Area Telescope is unlikely to originate from a single blob inside the BLR. This is because it moves outside the BLR in a time shorter than the flare duration, although emission by multiple blobs inside the BLR is possible. Also, γ -rays are unlikely to originate from outside of the BLR, due to the scattering of photons from an extended dust torus, since the cooling timescale would be too long to explain the observed short variability.« less

Effects of Io's volcanos on the plasma torus and Jupiter's magnetosphere

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

Cheng, A.F.

1980-12-01

Io's volcanism can have dominant effects on Jupiter's magnetosphere. A model is developed in which a neutral gas torus is formed at Io's orbit by volcanic SO/sub 2/ escaping from Io. Ionization and dissociation of volcanic SO/sub 2/ is shown to be the dominant source of plasma in Jupiter's magnetosphere. The failure of Voyager observations to confirm predictions of the magnetic anomaly model is naturally explained. A 30--50 KeV sulfur and oxygen ion plasma is formed in the outer magnetosphere, with density roughly equal to the proton density there, by ionization of sulfur and oxygen atoms on highly eccentric ellipticalmore » orbits around Jupiter. When these atoms are ionized in the outer magnetosphere, they are swept up by the Jovian magnetic field and achieve 30--50 keV energies. Such atoms are created by dissociative attachment of SO/sub 2/ by < or approx. =10 eV electrons. Substantial losses of radiation-belt charged particles result from passage through the neutral gas torus. Such losses can account for observed anomalies in charged particle depletions near Io; these could not be understood in terms of satellite sweeping alone. Substantial ionization energy loss occurs for < or approx. =1 MeV protons and < or approx. =100 keV electrons; losses of < or approx. =1 MeV protons are much greater than for comparable energy electrons. Losses of < or approx. =1 MeV per nucleon ions are also severe. Other consequences of the model include intrinsic time variability in the Jovian magnetosphere, on times > or approx. =10/sup 6/ s, caused by variations in Io's volcanic activity. Charged particle losses in the neutral gas torus tend to yield dumbbell-shaped pitch-angle distributions. Negative ions are predicted in the Io plasma torus.« less

DETECTION OF THE INTERMEDIATE-WIDTH EMISSION LINE REGION IN QUASAR OI 287 WITH THE BROAD EMISSION LINE REGION OBSCURED BY THE DUSTY TORUS

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

Li, Zhenzhen; Zhou, Hongyan; Wang, Huiyuan

2015-10-20

The existence of intermediate-width emission line regions (IELRs) in active galactic nuclei has been discussed for over two decades. A consensus, however, is yet to be arrived at due to the lack of convincing evidence for their detection. We present a detailed analysis of the broadband spectrophotometry of the partially obscured quasar OI 287. The ultraviolet intermediate-width emission lines (IELs) are very prominent, in high contrast to the corresponding broad emission lines (BELs) which are heavily suppressed by dust reddening. Assuming that the IELR is virialized, we estimated its distance to the central black hole to be ∼2.9 pc, similarmore » to the dust sublimation radius of ∼1.3 pc. Photo-ionization calculations suggest that the IELR has a hydrogen density of ∼10{sup 8.8}–10{sup 9.4} cm{sup −3}, within the range of values quoted for the dusty torus near the sublimation radius. Both its inferred location and physical conditions suggest that the IELR originates from the inner surface of the dusty torus. In the spectrum of this quasar, we identified only one narrow absorption-line system associated with the dusty material. With the aid of photo-ionization model calculations, we found that the obscuring material might originate from an outer region of the dusty torus. We speculate that the dusty torus, which is exposed to the central ionizing source, may produce IELs through photo-ionization processes, as well as obscure BELs as a natural “coronagraph.” Such a “coronagraph” could be found in a large number of partially obscured quasars and may be a useful tool to study IELRs.« less

Determining the torus covering factors for a sample of type 1 AGN in the local Universe

NASA Astrophysics Data System (ADS)

Ezhikode, Savithri H.; Gandhi, Poshak; Done, Chris; Ward, Martin; Dewangan, Gulab C.; Misra, Ranjeev; Philip, Ninan Sajeeth

2017-12-01

In the unified scheme of active galactic nuclei, a dusty torus absorbs and then reprocesses a fraction of the intrinsic luminosity which is emitted at longer wavelengths. Thus, subject to radiative transfer corrections, the fraction of the sky covered by the torus as seen from the central source (known as the covering factor fc) can be estimated from the ratio of the infrared to the bolometric luminosities of the source as fc = Ltorus/LBol. However, the uncertainty in determining LBol has made the estimation of covering factors by this technique difficult, especially for AGN in the local Universe where the peak of the observed spectral energy distributions lies in the UV (ultraviolet). Here, we determine the covering factors of an X-ray/optically selected sample of 51 type 1 AGN. The bolometric luminosities of these sources are derived using a self-consistent, energy-conserving model that estimates the contribution in the unobservable far-UV region, using multifrequency data obtained from SDSS, XMM-Newton, WISE, 2MASS and UKIDSS. We derive a mean value of fc ∼ 0.30 with a dispersion of 0.17. Sample correlations, combined with simulations, show that fc is more strongly anticorrelated with λEdd than with LBol. This points to large-scale torus geometry changes associated with the Eddington-dependent accretion flow, rather than a receding torus, with its inner sublimation radius determined solely by heating from the central source. Furthermore, we do not see any significant change in the distribution of fc for sub-samples of radio-loud sources or Narrow Line Seyfert 1 galaxies (NLS1s), though these sub-samples are small.

Hints of a Rotating Spiral Structure in the Innermost Regions around IRC+10216

NASA Astrophysics Data System (ADS)

Quintana-Lacaci, G.; Cernicharo, J.; Agúndez, M.; Velilla Prieto, L.; Castro-Carrizo, A.; Marcelino, N.; Cabezas, C.; Peña, I.; Alonso, J. L.; Zúñiga, J.; Requena, A.; Bastida, A.; Kalugina, Y.; Lique, F.; Guélin, M.

2016-02-01

The Atacama Large Millimeter/submillimeter Array is allowing us to study the innermost regions of the circumstellar envelopes of evolved stars with unprecedented precision and sensitivity. Key processes in the ejection of matter and dust from these objects occur in their inner zones. In this work, we present sub-arcsecond interferometric maps of transitions of metal-bearing molecules toward the prototypical C-rich evolved star IRC +10216. While Al-bearing molecules seem to be present as a roughly spherical shell, the molecular emission from the salts NaCl and KCl presents an elongation in the inner regions with a central minimum. In order to accurately analyze the emission from the NaCl rotational lines, we present new calculations of the collisional rates for this molecule based on new spectroscopic constants. The most plausible interpretation for the spatial distribution of the salts is a spiral with a NaCl mass of 0.08 {M}⊙ . Alternatively, a torus of gas and dust would result in structures similar to those observed. From the torus scenario we derive a mass of ˜1.1 × 10-4 {M}⊙ . In both cases, the spiral and the torus, the NaCl structure presents an inner minimum of 27 AU. In the case of the torus, the outer radius is 73 AU. The kinematics of both the spiral and the torus suggests that they are slowly expanding and rotating. Alternative explanations for the presence of the elongation are explored. The presence of these features only in KCl and NaCl might be a result of their comparatively high dipole moment with respect to the Al-bearing species.

Lagrange multiplier and Wess-Zumino variable as extra dimensions in the torus universe

NASA Astrophysics Data System (ADS)

Nejad, Salman Abarghouei; Dehghani, Mehdi; Monemzadeh, Majid

2018-01-01

We study the effect of the simplest geometry which is imposed via the topology of the universe by gauging non-relativistic particle model on torus and 3-torus with the help of symplectic formalism of constrained systems. Also, we obtain generators of gauge transformations for gauged models. Extracting corresponding Poisson structure of existed constraints, we show the effect of the shape of the universe on canonical structure of phase-spaces of models and suggest some phenomenology to prove the topology of the universe and probable non-commutative structure of the space. In addition, we show that the number of extra dimensions in the phase-spaces of gauged embedded models are exactly two. Moreover, in classical form, we talk over modification of Newton's second law in order to study the origin of the terms appeared in the gauged theory.

Quantum motion on a torus as a submanifold problem in a generalized Dirac's theory of second-class constraints

NASA Astrophysics Data System (ADS)

Xun, D. M.; Liu, Q. H.; Zhu, X. M.

2013-11-01

A generalization of Dirac's canonical quantization scheme for a system with second-class constraints is proposed, in which the fundamental commutation relations are constituted by all commutators between positions, momenta and Hamiltonian, so they are simultaneously quantized in a self-consistent manner, rather than by those between merely positions and momenta which leads to ambiguous forms of the Hamiltonian and the momenta. The application of the generalized scheme to the quantum motion on a torus leads to a remarkable result: the quantum theory is inconsistent if built up in an intrinsic geometric manner, whereas it becomes consistent within an extrinsic examination of the torus as a submanifold in three dimensional flat space with the use of the Cartesian coordinate system. The geometric momentum and potential are then reasonably reproduced.

The P-Mesh: A Commodity-based Scalable Network Architecture for Clusters

NASA Technical Reports Server (NTRS)

Nitzberg, Bill; Kuszmaul, Chris; Stockdale, Ian; Becker, Jeff; Jiang, John; Wong, Parkson; Tweten, David (Technical Monitor)

1998-01-01

We designed a new network architecture, the P-Mesh which combines the scalability and fault resilience of a torus with the performance of a switch. We compare the scalability, performance, and cost of the hub, switch, torus, tree, and P-Mesh architectures. The latter three are capable of scaling to thousands of nodes, however, the torus has severe performance limitations with that many processors. The tree and P-Mesh have similar latency, bandwidth, and bisection bandwidth, but the P-Mesh outperforms the switch architecture (a lower bound for tree performance) on 16-node NAB Parallel Benchmark tests by up to 23%, and costs 40% less. Further, the P-Mesh has better fault resilience characteristics. The P-Mesh architecture trades increased management overhead for lower cost, and is a good bridging technology while the price of tree uplinks is expensive.

On the theory of group generation of stars

NASA Technical Reports Server (NTRS)

Zhilyayev, B. Y.; Porfiryev, V. V.; Shulman, L. M.

1973-01-01

The hypothesis proposed is that topology of a rotating gaseous cloud can be variable in the contraction process. Due to rotation an originally spherical cloud is transformed into a toroidal body. The contraction of a thin torus is considered with different suppositions on cooling the gas. In the determined time the torus will become gravitationally unstable. The excitation of Jeans' waves is shown to result in the disintegration of the torus into fragments. The number of the fragments and their mass distributions are calculated. The proposed hypothesis on toroidal stages in stellar evolution can remove some difficulties in the theory of structure and evolution of stars, such as absence of limitary stars, distribution of rotation velocities of early-type stars, origin of poloidal magnetic fields and decline rotators with the magnetic axis orthogonal to the axis of rotation.

Outer satellite atmospheres: Their extended nature and planetary interactions

NASA Technical Reports Server (NTRS)

Smyth, W. H.; Combi, M. R.

1984-01-01

Model calculations for the brightness of the sodium cloud in Region A were performed to clarify the role played by the plasma torus sink in producing the east-west intensity asymmetry observed in the sodium D-lines. It was determined that the east-west electric field, proposed by Barbosa and Kievelson (1983) and Ip and Goertz (1983) to explain the dawn-dusk asymmetry in the torus ion emissions measured by the Voyager UVS instrument, could also produce the east-west sodium intensity asymmetry discovered earlier by Bergstralh et al. (1975, 1977). Model results for the directional features of the sodium cloud are also reported. The completion of the development of the Io potassium cloud model, progress in improving the Titan hydrogen torus model, and efforts in developing our model for hydrogen cometary atmospheres are also discussed.

Image restoration consequences of the lack of a two variable fundamental theorem of algebra

NASA Technical Reports Server (NTRS)

Kreznar, J. E.

1977-01-01

It has been shown that, at least for one pair of otherwise attractive spaces of images and operators, singular convolution operators do not necessarily have nonsingular neighbors. This result is a nuisance in image restoration. It is suggested that this difficulty might be overcome if the following three conditions are satisfied: (1) a weaker constraint than absolute summability can be identified for useful operators: (2) if the z-transform of an operator has at most a finite number of zeros on the unit torus, then the inverse z-transform formula yields an inverse operator meeting the weaker constraint: and (3) operators whose z-transforms are zero in a set of real, closed curves on the unit torus have neighbors which are zero in only a finite set of points on the unit torus.

ESA's high-energy observatories spot doughnut-shaped cloud with a black-hole filling

NASA Astrophysics Data System (ADS)

2004-07-01

hi-res Size hi-res: 7265 KB Credits: ESA, V. Beckmann (GSFC) Doughnut-shaped cloud surrounds black hole This artist's impression shows the thick dust torus that astronomers believe surrounds supermassive black holes and their accretion discs, like the one harboured in the nucleus of the spiral galaxy NGC 4388. When the torus is seen `edge-on’ as in this case, the visible light emitted by the accretion disc is partially blocked. However, the sharp X-ray and gamma-ray eyes of XMM-Newton and Integral can peer through the thick dust and see how the energy released by the accretion disc interacts with and is absorbed by the torus. Black holes are objects so compact and with gravity so strong that not even light can escape from them. Scientists think that `supermassive’ black holes are located in the cores of most galaxies, including our Milky Way galaxy. They can contain the mass of thousands of millions of suns, confined within a region no larger than our Solar System. They appear to be surrounded by a hot, thin disk of accreting gas and, farther out, the thick doughnut-shaped torus. Depending on the inclination of the torus, it can hide the black hole and the hot accretion disc from the line of sight. Galaxies in which a torus blocks the light from the central accretion disc are called `Seyfert 2’ types and are usually faint to optical telescopes. Another theory, however, is that these galaxies appear rather faint because the central black hole is not actively accreting gas and the disc surrounding it is therefore faint. An international team of astronomers led by Dr Volker Beckmann, Goddard Space Flight Center (Greenbelt, USA) has studied one of the nearest objects of this type, a spiral galaxy called NGC 4388, located 65 million light years away in the constellation Virgo. Since NGC 4388 is relatively close, and therefore unusually bright for its class, it is easier to study. Astronomers often study black holes that are aligned face-on, thus avoiding the enshrouding torus. However, Beckmann's group took the path less trodden and studied the central black hole by peering through the torus. With XMM-Newton and Integral, they could detect some of the X-rays and gamma rays, emitted by the accretion disc, which partially penetrate the torus. "By peering right into the torus, we see the black hole phenomenon in a whole new light, or lack of light, as the case may be here," Beckmann said. Beckmann's group saw how different processes around a black hole produce light at different wavelengths. For example, some of the gamma rays produced close to the black hole get absorbed by iron atoms in the torus and are re-emitted at a lower energy. This in fact is how the scientists knew they were seeing `reprocessed’ light farther out. Also, because of the line of sight towards NGC 4388, they knew this iron was from a torus on the same plane as the accretion disk, and not from gas clouds `above’ or `below’ the accretion disk. This new view through the haze has provided valuable insight into the relationship between the black hole, its accretion disc and the doughnut, and supports the torus model in several ways. Gas in the accretion disc close to the black hole reaches high speeds and temperatures (over 100 million degrees, hotter than the Sun) as it races toward the void. The gas radiates predominantly at high energies, in the X-ray wavelengths. According to Beckmann, this light is able to escape the black hole because it is still outside of its border, but ultimately collides with matter in the torus. Some of it is absorbed; some of it is reflected at different wavelengths, like sunlight penetrating a cloud; and the very energetic gamma rays pierce through. "This torus is not as dense as a real doughnut or a true German Krapfen, but it is far hotter - up to a thousand degrees - and loaded with many more calories," Beckmann said. The new observations also pinpoint the origin of the high-energy emission from NGC 4388. While the lower-energy X-rays seen by XMM-Newton appear to come from a diffuse emission, far away from the black hole, the higher-energy X-rays detected by Integral are directly related to the black hole activity. The team could infer the doughnut’s structure and its distance from the black hole by virtue of light that was either reflected or completely absorbed. The torus itself appears to be several hundred light years from the black hole, although the observation could not gauge its diameter, from inside to outside. The result marks the clearest observation of an obscured black hole in X-ray and gamma-ray `colours’, a span of energy nearly a million times wider than the window of visible light, from red to violet. Multi-wavelength studies are increasingly important to understanding black holes, as already demonstrated earlier this year. In May 2004, the European project known as the Astrophysical Virtual Observatory, in which ESA plays a major role, found 30 supermassive black holes that had previously escaped detection behind masking dust clouds. Note for editors This result will appear on The Astrophysical Journal. Besides Volker Beckmann, the author list includes Neil Gehrels, Pascal Favre, Roland Walter, Thierry Courvoisier, Pierre-Olivier Petrucci and Julien Malzac. For more information about the Astrophysical Virtual Observatory programme and how it has allowed European scientists to discover a number of previously hidden black holes, see: http://www.spacetelescope.org/news/html/heic0409.html More about Integral The International Gamma Ray Astrophysics Laboratory (Integral) is the first space observatory that can simultaneously observe celestial objects in gamma rays, X-rays and visible light. Integral was launched on a Russian Proton rocket on 17 October 2002 into a highly elliptical orbit around Earth. Its principal targets include regions of the galaxy where chemical elements are being produced and compact objects, such as black holes. More information on Integral can be found at: http://www.esa.int/esaSC/SEM9P5374OD_0_spk.html More about XMM-Newton XMM-Newton can detect more X-ray sources than any previous observatory and is helping to solve many cosmic mysteries of the violent Universe, from black holes to the formation of galaxies. It was launched on 10 December 1999, using an Ariane-5 rocket from French Guiana. It is expected to return data for a decade. XMM-Newton’s high-tech design uses over 170 wafer-thin cylindrical mirrors spread over three telescopes. Its orbit takes it almost a third of the way to the Moon, so that astronomers can enjoy long, uninterrupted views of celestial objects. More information on XMM-Newton can be found at: http://www.esa.int/esaSC/SEMM8IGHZTD_1_spk.html

Using Gravity and Topography to Map Mars' Crustal Thickness

NASA Image and Video Library

2016-03-21

Newly detailed mapping of local variations in Mars' gravitational pull on orbiters (center), combined with topographical mapping of the planet's mountains and valleys (left) yields the best-yet mapping of Mars' crustal thickness (right). These three views of global mapping are centered at 90 degrees west longitude, showing portions of the planet that include tall volcanoes on the left and the deep Valles Marineris canyon system just right of center. Additional views of these global maps are available at http://svs.gsfc.nasa.gov/goto?4436. The new map of Mars' gravity (center) results from analysis of the planet's gravitational effects on orbiters passing over each location on the globe. The data come from many years of using NASA's Deep Space Network to track positions and velocities of NASA's Mars Global Surveyor, Mars Odyssey and Mars Reconnaissance Orbiter. If Mars were a perfectly smooth sphere of uniform density, the gravity experienced by the spacecraft would be exactly the same everywhere. But like other rocky bodies in the solar system, including Earth, Mars has both a bumpy surface and a lumpy interior. As the spacecraft fly in their orbits, they experience slight variations in gravity caused by both of these irregularities, variations which show up as small changes in the velocity and altitude of the three spacecraft. The "free-air" gravity map presents the results without any adjustment for the known bumpiness of Mars' surface. Local gravitational variations in acceleration are expressed in units called gals or galileos. The color-coding key beneath the center map indicates how colors on the map correspond to mGal (milligal) values. The map on the left shows the known bumpiness, or topography, of the Martian surface, using data from the Mars Orbiter Laser Altimeter (MOLA) instrument on Mars Global Surveyor. Mars has no actual "sea level," but does have a defined zero elevation level. The color-coding key beneath this map indicates how the colors correspond to elevations above or below zero, in kilometers. Analysis that subtracts effects of the surface topography from the free-air gravity mapping, combined with an assumption that crust material has a uniform density, leads to the derived mapping of crustal thickness -- or subsurface "lumpiness" -- on the right. Highs in gravity indicate places where the denser mantle material beneath the crust is closer to the surface, and hence where the crust is thinner. The color-coding key for this map indicates how the colors on the map correspond to the thickness of the crust, in kilometers. http://photojournal.jpl.nasa.gov/catalog/PIA20277

Quantum Torus Algebras and B(C)-Type Toda Systems

NASA Astrophysics Data System (ADS)

Wang, Na; Li, Chuanzhong

2017-12-01

In this paper, we construct a new even constrained B(C)-type Toda hierarchy and derive its B(C)-type Block-type additional symmetry. Also we generalize the B(C)-type Toda hierarchy to the N-component B(C)-type Toda hierarchy which is proved to have symmetries of a coupled \\bigotimes ^NQT_+ algebra ( N-fold direct product of the positive half of the quantum torus algebra QT).

Observations of electron gyroharmonic waves and the structure of the 10 torus

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

Birmingham, T.J.; Alexander, J.K.; Desch, M.D.

1981-09-30

Narrow-banded emission were observed by the planetary radio astronomy experiment on the Voyager 1 spacecraft as it traversed the Io plasma torus. These waves occur between harmonics of the electron gyrofrequency and are the Jovian analogue of electrostatic emissions observed and theoretically studied for the terrestrial magnetosphere. The observed frequencies always include the component near f/sub uhr'/ the upper hydbrid resonant frequency, but the distribution of the other observed emissions varies in a systematic way with position in the torus. A detailed discussion of the observations is presented. A refined model of the electron density variation, based on identification ofmore » the f/sub uhr/ line, is also included. Spectra of the observed waves are analyzed in terms of the linear instability of an electron distribution function consisting of isotropic cold electrons and hot loss cone electrons. The positioning of the observed auxiliary harmonics with respect to f/sub uhr/ is shown to be an indicator of the cold to hot temperature ratio T/sub C//T/sub H/. It is concluded that this ratio increases systematically by an overall factor of perhaps 4 or 5 between the inner (Lapprox.5 R/sub J/) and outer (Lapprox.9 R/sub J/) portions of the torus. Other relevant plasma and spectroscopic data are discussed.« less

The Helicity Injected Torus Program

NASA Astrophysics Data System (ADS)

Jarboe, T. R.; Nelson, B. A.; Jewell, P. D.; Liptac, J. E.; McCollam, K. J.; Raman, R.; Redd, A. J.; Rogers, J. A.; Sieck, P. E.; Shumlak, U.; Smith, R. J.; Nagata, M.; Uyama, T.

1999-11-01

The Helicity Injected Torus--II (HIT--II) spherical torus is capable of both Coaxial Helicity Injection (CHI) and transformer action current drive. HIT--II has a major radius R = 0.3, minor radius a = 0.2, aspect ratio A = R/a = 1.5, with an on axis magnetic field of up to Bo = 0.67 T. HIT--II provides equilibrium control, CHI flux boundary conditions, and transformer action using 28 poloidal field coils, using active flux feedback control. HIT--II has driven up to 200 kA of plasma current, using either CHI or transformer drive. An overview and recent results of the HIT--II program will be presented. The development of a locked-electron current drive model for HIT and HIT--II has led to the design of a constant inductive helicity injection method for spherical torii. This method is incorporated in the design of the Helicity Injected Torus -- Steady Inductive (HIT-- SI)(T.R. Jarboe, Fusion Technology, 36) (1), p. 85, 1999 experiment. HIT--SI can form a high-beta spheromak, a low aspect ratio RFP, or a spherical tokamak in a steady-state manner without using electrodes. The HIT--SI design and methodology will be presented.

Structure of the entanglement entropy of (3+1)-dimensional gapped phases of matter

NASA Astrophysics Data System (ADS)

Zheng, Yunqin; He, Huan; Bradlyn, Barry; Cano, Jennifer; Neupert, Titus; Bernevig, B. Andrei

2018-05-01

We study the entanglement entropy of gapped phases of matter in three spatial dimensions. We focus in particular on size-independent contributions to the entropy across entanglement surfaces of arbitrary topologies. We show that for low energy fixed-point theories, the constant part of the entanglement entropy across any surface can be reduced to a linear combination of the entropies across a sphere and a torus. We first derive our results using strong sub-additivity inequalities along with assumptions about the entanglement entropy of fixed-point models, and identify the topological contribution by considering the renormalization group flow; in this way we give an explicit definition of topological entanglement entropy Stopo in (3+1)D, which sharpens previous results. We illustrate our results using several concrete examples and independent calculations, and show adding "twist" terms to the Lagrangian can change Stopo in (3+1)D. For the generalized Walker-Wang models, we find that the ground state degeneracy on a 3-torus is given by exp(-3 Stopo[T2] ) in terms of the topological entanglement entropy across a 2-torus. We conjecture that a similar relationship holds for Abelian theories in (d +1 ) dimensional spacetime, with the ground state degeneracy on the d -torus given by exp(-d Stopo[Td -1] ) .

Reddening and He i{sup ∗} λ 10830 Absorption Lines in Three Narrow-line Seyfert 1 Galaxies

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

Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng

We report the detection of heavy reddening and the He i* λ 10830 absorption lines at the active galactic nucleus (AGN) redshift in three narrow-line Seyfert 1 galaxies: SDSS J091848.61+211717.0, SDSS J111354.66+124439.0, and SDSS J122749.13+321458.9. They exhibit very red optical to near-infrared colors, narrow Balmer/Paschen broad emission lines and He i* λ 10830 absorption lines. The ultraviolet-optical-infrared nucleus continua are reddened by the SMC extinction law of E ( B − V ) ∼ 0.74, 1.17, and 1.24 mag for three objects, which are highly consistent with the values obtained from the broad-line Balmer decrements, but larger than those ofmore » narrow emission lines. The reddening analysis suggests that the extinction dust simultaneously obscures the accretion disk, the broad emission-line region, and the hot dust from the inner edge of the torus. It is possible that the dust obscuring the AGN structures is the dusty torus itself. Furthermore, the Cloudy analysis of the He i* λ 10830 absorption lines proposes the distance of the absorption materials to be the extend scale of the torus, which greatly increases probabilities of the obscure and absorption materials being the dusty torus.« less

SPATIALLY RESOLVED HCN ABSORPTION FEATURES IN THE CIRCUMNUCLEAR REGION OF NGC 1052

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

Sawada-Satoh, Satoko; Roh, Duk-Gyoo; Oh, Se-Jin

We present the first VLBI detection of HCN molecular absorption in the nearby active galactic nucleus NGC 1052. Utilizing the 1 mas resolution achieved by the Korean VLBI Network, we have spatially resolved the HCN absorption against a double-sided nuclear jet structure. Two velocity features of HCN absorption are detected significantly at the radial velocity of 1656 and 1719 km s{sup −1}, redshifted by 149 and 212 km s{sup −1} with respect to the systemic velocity of the galaxy. The column density of the HCN molecule is estimated to be 10{sup 15}–10{sup 16} cm{sup −2}, assuming an excitation temperature ofmore » 100–230 K. The absorption features show high optical depth localized on the receding jet side, where the free–free absorption occurred due to the circumnuclear torus. The size of the foreground absorbing molecular gas is estimated to be on approximately one-parsec scales, which agrees well with the approximate size of the circumnuclear torus. HCN absorbing gas is likely to be several clumps smaller than 0.1 pc inside the circumnuclear torus. The redshifted velocities of the HCN absorption features imply that HCN absorbing gas traces ongoing infall motion inside the circumnuclear torus onto the central engine.« less

Deuterium-tritium pulse propulsion with hydrogen as propellant and the entire space-craft as a gigavolt capacitor for ignition

NASA Astrophysics Data System (ADS)

Winterberg, F.

2013-08-01

A deuterium-tritium (DT) nuclear pulse propulsion concept for fast interplanetary transport is proposed utilizing almost all the energy for thrust and without the need for a large radiator: By letting the thermonuclear micro-explosion take place in the center of a liquid hydrogen sphere with the radius of the sphere large enough to slow down and absorb the neutrons of the DT fusion reaction, heating the hydrogen to a fully ionized plasma at a temperature of ∼105 K. By using the entire spacecraft as a magnetically insulated gigavolt capacitor, igniting the DT micro-explosion with an intense GeV ion beam discharging the gigavolt capacitor, possible if the space craft has the topology of a torus.

AGN Science with STROBE-X

NASA Astrophysics Data System (ADS)

Ballantyne, David; Balokovic, Mislav; Garcia, Javier; Koss, Michael; STROBE-X

2018-01-01

The probe concept STROBE-X, with its combination of large collecting area, wide-field monitor, broad bandpass, and rapid timing capability, is a powerful tool for studying many aspects of AGN astrophysics. This unique combination of features opens up the possibility for studying AGNs in ways current and other future missions are unable to accomplish. Here, we show a few of the novel new investigations made possible by STROBE-X: probing the structure of the BLR and torus with reverberation of the narrow Fe Kα line and line-of-sight column density, tracking changes in coronal parameters, investigating the origin of the soft excess, Fe Kα emission line surveys, and efficient Compton-thick characterization. Additional ideas and suggestions are always welcome and can be communicated to any member of the STROBE-X team.

A Bumpy Road and a Bridge too Far? An Analysis of the Realistic Bridging and Horizontal Construction Capabilities of the Canadian Military Engineers in the Force 2013 Structure

DTIC Science & Technology

2012-05-17

the national security strategy? Liddell Hart describes this difficult challenge faced by all socially conservative states. They must find the type of... challenges and circumstances while working within an economic framework that necessitates choice.”23 TTCP describes the CBP process as a method that involves...a capability gap. Then the Army purchased quick solutions and fielded them for immediate deployment to theatre. Their generation satisfied an urgent

Coronography with a dynamic hologram

NASA Astrophysics Data System (ADS)

Ricci, D.; Le Coroller, H.; Piron, P.

2010-10-01

An innovative solution to improve the performances of coronagraphs consists in adding, in the optical scheme, a dynamic hologram removing most of the residual speckle starlight. Our simulations show that the detection limit in the flux ratio between a host star and a very near planet, in the case of wavefront bumpiness imperfections at lambda/20 (resp. lambda/100), improves over a factor 1000 (resp. 10000) when equipped with a hologram, allowing to direct image an exo-Earth at a distance of 11 parsec with a ∼6.5m space telescope.

Equivariant Gromov-Witten Invariants of Algebraic GKM Manifolds

NASA Astrophysics Data System (ADS)

Liu, Chiu-Chu Melissa; Sheshmani, Artan

2017-07-01

An algebraic GKM manifold is a non-singular algebraic variety equipped with an algebraic action of an algebraic torus, with only finitely many torus fixed points and finitely many 1-dimensional orbits. In this expository article, we use virtual localization to express equivariant Gromov-Witten invariants of any algebraic GKM manifold (which is not necessarily compact) in terms of Hodge integrals over moduli stacks of stable curves and the GKM graph of the GKM manifold.

Tightness of the Ising-Kac Model on the Two-Dimensional Torus

NASA Astrophysics Data System (ADS)

Hairer, Martin; Iberti, Massimo

2018-05-01

We consider the sequence of Gibbs measures of Ising models with Kac interaction defined on a periodic two-dimensional discrete torus near criticality. Using the convergence of the Glauber dynamic proven by Mourrat and Weber (Commun Pure Appl Math 70:717-812, 2017) and a method by Tsatsoulis and Weber employed in (arXiv:1609.08447 2016), we show tightness for the sequence of Gibbs measures of the Ising-Kac model near criticality and characterise the law of the limit as the Φ ^4_2 measure on the torus. Our result is very similar to the one obtained by Cassandro et al. (J Stat Phys 78(3):1131-1138, 1995) on Z^2, but our strategy takes advantage of the dynamic, instead of correlation inequalities. In particular, our result covers the whole critical regime and does not require the large temperature/large mass/small coupling assumption present in earlier results.

Overview of the Helicity Injected Torus (HIT) Program

NASA Astrophysics Data System (ADS)

Redd, A. J.; Jarboe, T. R.; Hamp, W. T.; Nelson, B. A.; O'Neill, R. G.; Sieck, P. E.; Smith, R. J.; Sutphin, G. L.; Wrobel, J. S.

2007-06-01

The Helicity Injected Torus with Steady Inductive Helicity Injection (HIT-SI) consists of a "bowtie"-shaped axisymmetric confinement region, with two half-torus helicity injectors mounted on each side of the axisymmetric flux conserver [Sieck et al, IEEE Trans. Plasma Sci., v.33, p.723 (2005); Jarboe, Fusion Technology, v.36, p.85 (1999)]. Current and flux are driven sinusoidally with time in each injector, with the goal of generating and sustaining an axisymmetric spheromak in the main confinement region. Improvements in machine conditioning have enabled systematic study of HIT-SI discharges with significant toroidal current ITOR, including cases in which this current ITOR switches sign one or more times during the discharge. Statistical studies of all HIT-SI discharges to date demonstrate a minimum injected power to form significant ITOR, and that the maximum ITOR scales approximately linearly with the total injected power.

Short interval expansion of Rényi entropy on torus

NASA Astrophysics Data System (ADS)

Chen, Bin; Wu, Jun-Bao; Zhang, Jia-ju

2016-08-01

We investigate the short interval expansion of the Rényi entropy for two-dimensional conformal field theory (CFT) on a torus. We require the length of the interval ℓ to be small with respect to the spatial and temporal sizes of the torus. The operator product expansion of the twist operators allows us to compute the short interval expansion of the Rényi entropy at any temperature. In particular, we pay special attention to the large c CFTs dual to the AdS3 gravity and its cousins. At both low and high temperature limits, we read the Rényi entropies to order ℓ6, and find good agreements with holographic results. Moreover, the expansion allows us to read 1 /c contribution, which is hard to get by expanding the thermal density matrix. We generalize the study to the case with the chemical potential as well.

Limit on rotational energy available to excite Jovian aurora

NASA Technical Reports Server (NTRS)

Eviatar, A.; Siscoe, G. L.

1980-01-01

There is a fundamental relationship between the power that is extracted from Jupiter's rotation to drive magnetospheric processes and the rate at which mass is injected into the Io plasma torus. Half of this power is consumed by bulk motion of the plasma and the other half represents an upper limit on the energy from rotation available for dissipation and in particular to excite the Jovian aurora. Since the rotation of the planet is the only plausible source of energy, the power inferred from the observed auroral intensities requires a plasma injection rate of 2.6 x 10 to the 29th AMU/sec or greater. This in turn leads to a residence time of a torus particle of 48 days or less. These results raise doubts about the applicability of equilibrium thermodynamics to the determination of plasma parameters in the Io torus.

Excitation basis for (3+1)d topological phases

NASA Astrophysics Data System (ADS)

Delcamp, Clement

2017-12-01

We consider an exactly solvable model in 3+1 dimensions, based on a finite group, which is a natural generalization of Kitaev's quantum double model. The corresponding lattice Hamiltonian yields excitations located at torus-boundaries. By cutting open the three-torus, we obtain a manifold bounded by two tori which supports states satisfying a higher-dimensional version of Ocneanu's tube algebra. This defines an algebraic structure extending the Drinfel'd double. Its irreducible representations, labeled by two fluxes and one charge, characterize the torus-excitations. The tensor product of such representations is introduced in order to construct a basis for (3+1)d gauge models which relies upon the fusion of the defect excitations. This basis is defined on manifolds of the form Σ × S_1 , with Σ a two-dimensional Riemann surface. As such, our construction is closely related to dimensional reduction from (3+1)d to (2+1)d topological orders.

Modeling the Enceladus Plasma and Neutral Torus in Saturn's Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Jia, Yingdong; Russell, C. T.; Khurana, K. K.; Gombosi, T. I.

2010-10-01

Saturn's moon Enceladus, produces hundreds of kilograms of water vapor every second. These water molecules form a neutral torus which is comparable to the Io torus in the Jovian system. These molecules become ionized producing a plasma disk in the inner magnetosphere of Saturn which exchanges momentum with the "corotating” magnetospheric plasma. To balance the centripetal force of this plasma disk, Saturn's magnetic field is stretched in the radial direction and to accelerate the azimuthal speed to corotational values, the field is stretched in the azimuthal direction. At Enceladus the massive pickup of new ions from its plume slows down the corotating flow and breaks this force balance, causing plasma flows in the radial direction. Such radial flows in the inner magnetosphere of Saturn are supported by Cassini observations using various particle and field instruments. In this study we develop a global model of the inner magnetosphere of Saturn in an attempt to reproduce such processes.

3-D Object Pose Determination Using Complex EGI

DTIC Science & Technology

1990-10-01

the length of edges of the polyhedron from the EGI. Dane and Bajcsy [4] make use of the Gaussian Image to spatially segment a group of range points...involving real range data of two smooth objects were conducted. The two smooth objects are the torus and ellipsoid, whose databases have been created...in the simulations earlier. 5.0.1 Implementational Issues The torus and ellipsoid were crafted out of clay to resemble the models whose databases were

Reflectionless Discrete Schrödinger Operators are Spectrally Atypical

NASA Astrophysics Data System (ADS)

VandenBoom, Tom

2017-12-01

We prove that, if an isospectral torus contains a discrete Schrödinger operator with nonconstant potential, the shift dynamics on that torus cannot be minimal. Consequently, we specify a generic sense in which finite unions of nondegenerate closed intervals having capacity one are not the spectrum of any reflectionless discrete Schrödinger operator. We also show that the only reflectionless discrete Schrödinger operators having zero, one, or two spectral gaps are periodic.

Symmetry-breaking Hopf bifurcations to 1-, 2-, and 3-tori in small-aspect-ratio counterrotating Taylor-Couette flow.

PubMed

Altmeyer, S; Do, Y; Marques, F; Lopez, J M

2012-10-01

The nonlinear dynamics of Taylor-Couette flow in a small-aspect-ratio wide-gap annulus in the counterrotating regime is investigated by solving the full three-dimensional Navier-Stokes equations. The system is invariant under arbitrary rotations about the axis, reflection about the annulus midplane, and time translations. A systematic investigation is presented both in terms of the flow physics elucidated from the numerical simulations and from a dynamical system perspective provided by equivariant normal form theory. The dynamics are primarily associated with the behavior of the jet of angular momentum that emerges from the inner cylinder boundary layer at about the midplane. The sequence of bifurcations as the differential rotation is increased consists of an axisymmetric Hopf bifurcation breaking the reflection symmetry of the basic state leading to an axisymmetric limit cycle with a half-period-flip spatiotemporal symmetry. This undergoes a Hopf bifurcation breaking axisymmetry, leading to quasiperiodic solutions evolving on a 2-torus that is setwise symmetric. These undergo a further Hopf bifurcation, introducing a third incommensurate frequency leading to a 3-torus that is also setwise symmetric. On the 3-torus, as the differential rotation is further increased, a saddle-node-invariant-circle bifurcation takes place, destroying the 3-torus and leaving a pair of symmetrically related 2-tori states on which all symmetries of the system have been broken.

Dusty Winds in Active Galactic Nuclei: Reconciling Observations with Models

NASA Astrophysics Data System (ADS)

Hönig, Sebastian F.; Kishimoto, Makoto

2017-04-01

This Letter presents a revised radiative transfer model for the infrared (IR) emission of active galactic nuclei (AGNs). While current models assume that the IR is emitted from a dusty torus in the equatorial plane of the AGNs, spatially resolved observations indicate that the majority of the IR emission from ≲100 pc in many AGNs originates from the polar region, contradicting classical torus models. The new model CAT3D-WIND builds upon the suggestion that the dusty gas around the AGNs consists of an inflowing disk and an outflowing wind. Here, it is demonstrated that (1) such disk+wind models cover overall a similar parameter range of observed spectral features in the IR as classical clumpy torus models, e.g., the silicate feature strengths and mid-IR spectral slopes, (2) they reproduce the 3-5 μm bump observed in many type 1 AGNs unlike torus models, and (3) they are able to explain polar emission features seen in IR interferometry, even for type 1 AGNs at relatively low inclination, as demonstrated for NGC3783. These characteristics make it possible to reconcile radiative transfer models with observations and provide further evidence of a two-component parsec-scale dusty medium around AGNs: the disk gives rise to the 3-5 μm near-IR component, while the wind produces the mid-IR emission. The model SEDs will be made available for download.

A dynamic magnetic tension force as the cause of failed solar eruptions

DOE Data Explorer

Myers, Clayton E. [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); ] (ORCID:0000000345398406); Yamada, Maasaki [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000349961649); Ji, Hantao [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Laboratory for Space Environment and Physical Sciences, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China] (ORCID:0000000196009963); Yoo, Jongsoo [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000338811995); Fox, William [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:000000016289858X); Jara-Almonte, Jonathan [Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); ] (ORCID:0000000307606198); Savcheva, Antonia [Harvard†“ Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA] (ORCID:000000025598046X); DeLuca, Edward E. [Harvard†“ Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA] (ORCID:0000000174162895)

2015-12-11

Coronal mass ejections are solar eruptions driven by a sudden release of magnetic energy stored in the Sun’s corona. In many cases, this magnetic energy is stored in long-lived, arched structures called magnetic flux ropes. When a flux rope destabilizes, it can either erupt and produce a coronal mass ejection or fail and collapse back towards the Sun. The prevailing belief is that the outcome of a given event is determined by a magnetohydrodynamic force imbalance called the torus instability. This belief is challenged, however, by observations indicating that torus-unstable flux ropes sometimes fail to erupt. This contradiction has not yet been resolved because of a lack of coronal magnetic field measurements and the limitations of idealized numerical modelling. Here we report the results of a laboratory experiment that reveal a previously unknown eruption criterion below which torus-unstable flux ropes fail to erupt. We find that such ‘failed torus’ events occur when the guide magnetic field (that is, the ambient field that runs toroidally along the flux rope) is strong enough to prevent the flux rope from kinking. Under these conditions, the guide field interacts with electric currents in the flux rope to produce a dynamic toroidal field tension force that halts the eruption. This magnetic tension force is missing from existing eruption models, which is why such models cannot explain or predict failed torus events.

Compact torus accelerator as a driver for ICF

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

Tobin, M.T.; Meier, W.R.; Morse, E.C.

1986-01-01

The authors have carried out further investigations of the technical issues associated with using a compact torus (CT) accelerator as a driver for inertial confinement fusion (ICF). In a CT accelerator, a magnetically confined, torus-shaped plasma is compressed, accelerated, and focused by two concentric electrodes. After its initial formation, the torus shape is maintained for lifetimes exceeding 1 ms by inherent poloidal and toroidal currents. Hartman suggests acceleration and focusing of such a plasma ring will not cause dissolution within certain constraints. In this study, we evaluated a point design based on an available capacitor bank energy of 9.2 MJ.more » This accelerator, which was modeled by a zero-dimensional code, produces a xenon plasma ring with a 0.73-cm radius, a velocity of 4.14 x 10/sup 9/ cm/s, and a mass of 4.42 ..mu..g. The energy of the plasma ring as it leaves the accelerator is 3.8 MJ, or 41% of the capacitor bank energy. Our studies confirm the feasibility of producing a plasma ring with the characteristics required to induce fusion in an ICF target with a gain greater than 50. The low cost and high efficiency of the CT accelerator are particularly attractive. Uncertainties concerning propagation, accelerator lifetime, and power supply must be resolved to establish the viability of the accelerator as an ICF driver.« less

A broad survey of hydraulic and mechanical safety in the xylem of conifers

PubMed Central

Bouche, Pauline S.; Larter, Maximilien; Domec, Jean-Christophe; Burlett, Régis; Gasson, Peter; Jansen, Steven; Delzon, Sylvain

2014-01-01

Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region. PMID:24916072

X-Ray Bolometric Corrections for Compton-thick Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Brightman, M.; Baloković, M.; Ballantyne, D. R.; Bauer, F. E.; Boorman, P.; Buchner, J.; Brandt, W. N.; Comastri, A.; Del Moro, A.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Koss, M.; Lanz, L.; Masini, A.; Ricci, C.; Stern, D.; Vasudevan, R.; Walton, D. J.

2017-07-01

We present X-ray bolometric correction factors, {κ }{Bol} (≡{L}{Bol}/{L}{{X}}), for Compton-thick (CT) active galactic nuclei (AGNs) with the aim of testing AGN torus models, probing orientation effects, and estimating the bolometric output of the most obscured AGNs. We adopt bolometric luminosities, {L}{Bol}, from literature infrared (IR) torus modeling and compile published intrinsic 2-10 keV X-ray luminosities, {L}{{X}}, from X-ray torus modeling of NuSTAR data. Our sample consists of 10 local CT AGNs, where both of these estimates are available. We test for systematic differences in {κ }{Bol} values produced when using two widely used IR torus models and two widely used X-ray torus models, finding consistency within the uncertainties. We find that the mean {κ }{Bol} of our sample in the range of {L}{Bol}≈ {10}42{--}{10}45 {erg} {{{s}}}-1 is log10 {κ }{Bol} = 1.44 ± 0.12 with an intrinsic scatter of ˜0.2 dex, and that our derived {κ }{Bol} values are consistent with previously established relationships between {κ }{Bol} and {L}{Bol} and {κ }{Bol} and Eddington ratio ({λ }{Edd}). We investigate if {κ }{Bol} is dependent on {N}{{H}} by comparing our results on CT AGNs to published results on less-obscured AGNs, finding no significant dependence. Since many of our sample are megamaser AGNs, known to be viewed edge-on, and furthermore under the assumptions of AGN unification whereby unobscured AGNs are viewed face-on, our result implies that the X-ray emitting corona is not strongly anisotropic. Finally, we present {κ }{Bol} values for CT AGNs identified in X-ray surveys as a function of their observed {L}{{X}}, where an estimate of their intrinsic {L}{{X}} is not available, and redshift, useful for estimating the bolometric output of the most obscured AGNs across cosmic time.

Application of inflatable aeroshell structures for Entry Descent and Landing

NASA Astrophysics Data System (ADS)

Jurewicz, David; Lichodziejewski, Leo; Tutt, Ben; Gilles, Brian; Brown, Glen

Future space missions will require improvements in the Entry, Descent, and Landing (EDL) phases of the mission architecture. The focus of this paper is to discuss recent advances in analysis, fabrication techniques, ground testing, and flight testing of a stacked torus Hypersonic Inflatable Aerodynamic Decelerator (HIAD) and its application to the future of EDL. The primary structure of a stacked torus HIAD consists of nested inflatable tori of increasing major diameter bonded and strapped to form a rigid structure after inflation. The underlying structure of the decelerator is covered with a flexible Thermal Protection System (TPS) capable of high heat flux. The inflatable aeroshell and TPS are packed around a centerbody within the launch fairing and deployed prior to atmospheric reentry. Recent fabrication of multiple HIADs between 3 and 6 meters has led to significant advances in process control and validation of the scalability of the technology. Progress has been made in generating and validating LS-DYNA FEA models to replicate flight loading in addition to analytical models of substructures. Coupon and component testing has improved the validation of modeling techniques and assumptions at the subsystem level. A ground testing campaign at the National Full-Scale Aerodynamics Center (NFAC) wind tunnel at NASA Ames Research center generated substantial aerodynamic and loading data to validate full system modeling with comparable dynamic pressures to a hypersonic reentry. The Inflatable Reentry Vehicle - 3 (IRVE-3) sounding rocket flight test was conducted with NASA Langley Research Center in July 2012. The IRVE-3 mission verified the structural and thermal performance of the stacked torus configuration. Further development of the stacked torus configuration is currently being conducted to increase the thermal capability, deceleration loads, and understanding of the interactions and effects of constituent components. The results of this research have expanded the- feasible flight envelope of stacked torus HIAD designs over a range of sizes, loading conditions, and heating.

X-RAY ABSORPTION, NUCLEAR INFRARED EMISSION, AND DUST COVERING FACTORS OF AGNs: TESTING UNIFICATION SCHEMES

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

Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.

2016-03-10

We present the distributions of the geometrical covering factors of the dusty tori (f{sub 2}) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2–10 keV luminosities between 10{sup 42} and 10{sup 46} erg s{sup −1}, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1–20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Opticallymore » classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f{sub 2} than type 1 AGNs. Nevertheless, ∼20% of type 1 AGNs have tori with large covering factors, while ∼23%–28% of type 2 AGNs have tori with small covering factors. Low f{sub 2} are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f{sub 2} increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f{sub 2} determine the optical appearance of an AGN and control the shape of the rest-frame ∼1–20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.« less

Multipartite entanglement via the Mayer-Vietoris theorem

NASA Astrophysics Data System (ADS)

Patrascu, Andrei T.

2017-10-01

The connection between entanglement and topology manifests itself in the form of the ER-EPR duality. This statement however refers to the maximally entangled states only. In this article I study the multipartite entanglement and the way in which it relates to the topological interpretation of the ER-EPR duality. The 2 dimensional genus 1 torus will be generalised to a n-dimensional general torus, where the information about the multipartite entanglement will be encoded in the higher inclusion maps of the Mayer-Vietorist sequence.

Short-scale turbulent fluctuations driven by the electron-temperature gradient in the national spherical torus experiment.

PubMed

Mazzucato, E; Smith, D R; Bell, R E; Kaye, S M; Hosea, J C; LeBlanc, B P; Wilson, J R; Ryan, P M; Domier, C W; Luhmann, N C; Yuh, H; Lee, W; Park, H

2008-08-15

Measurements with coherent scattering of electromagnetic waves in plasmas of the National Spherical Torus Experiment indicate the existence of turbulent fluctuations in the range of wave numbers k perpendicular rho(e)=0.1-0.4, corresponding to a turbulence scale length nearly equal to the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.

Observing Cool Dust Around Active Galactic Nuclei Using the Sofia Telescope

NASA Astrophysics Data System (ADS)

Fuller, Lindsay

2017-02-01

Dust surrounding the supermassive black holes (SMBH) in active galactic nuclei (AGN) intercepts high-energy radiation caused by material rapidly encircling the black hole. The dust re-radiates at low-energy mid-infrared (MIR) wavelengths, which are highly attenuated by water vapor in the Earth's atmosphere. For ground-based telescopes, the atmosphere is completely opaque from 30 microns to the submillimeter regime, making ground-based observations at wavelengths longer than 30 microns impossible. Space-based telescopes can be costly, and are oftentimes very small (< 1 m). As an alternative, NASA built the Stratospheric Observatory For Infrared Astronomy (SOFIA) aircraft, a 2.5-m telescope carried on board a Boeing 747 airframe. In this dissertation, new photometric observations of 15 AGN are analyzed. They were obtained during Observing Cycles 2 and 4 on the SOFIA telescope using the 31.5 and 37.1 micron filters on the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST). NGC 1068 was observed in the 19.7, 31.5, and 37.1 micron filters using FORCAST, as well as the 53 micron filter on the HAWC+ instrument. Observed differences in AGN properties are largely explained by a unified model in which dust fills a toroidal region surrounding the SMBH, blocking direct view of the center in some lines of sight. Observations show that this dust lies in the central 1 - 10 pc from the black hole. Subarcsecond-resolution photometric and spectroscopic data between 1 - 20 microns have been used to compute the nuclear spectral energy distributions (SEDs) of the torus for most objects in this sample. Although these previous studies have effectively described torus model parameters, the lack of high spatial resolution observations at longer wavelengths leaves the SED largely unconstrained. Without 31.5 micron data, the model tends to overestimate the SED output and wavelength of peak emission, which is tentatively found between 30 - 40 microns. Including the 31.5 micron nuclear flux in the SED 1) reduces the number of clumpy torus models compatible with the data, and 2) modifies the model output for the outer radial extent of the torus. These observations of the central 0.1 - 1 kpc ( 3 - 4 arseconds) of the AGN sample are the highest resolution images available in the 30 - 40 micron wavelength range. However, for AGN at distances on the order of tens of Mpc, SOFIA cannot resolve the parsec-scale torus structure, and contamination from diffuse IR emission and star formation (SF) can contaminate nuclear observations. This dissertation focuses on isolating torus emission from diffuse extended emission in order to 1) add 30 - 40 micron photometric data to the IR SED of the torus and its model parameters, and 2) identify the origin of diffuse extended emission. Extended emission within the FWHM of SOFIA that is not associated with SF ostensibly originates in the narrow line region.

Spacetime Singularities in Quantum Gravity

NASA Astrophysics Data System (ADS)

Minassian, Eric A.

2000-04-01

Recent advances in 2+1 dimensional quantum gravity have provided tools to study the effects of quantization of spacetime on black hole and big bang/big crunch type singularities. I investigate effects of quantization of spacetime on singularities of the 2+1 dimensional BTZ black hole and the 2+1 dimensional torus universe. Hosoya has considered the BTZ black hole, and using a "quantum generalized affine parameter" (QGAP), has shown that, for some specific paths, quantum effects "smear" the singularities. Using gaussian wave functions as generic wave functions, I found that, for both BTZ black hole and the torus universe, there are families of paths that still reach the singularities with a finite QGAP, suggesting that singularities persist in quantum gravity. More realistic calculations, using modular invariant wave functions of Carlip and Nelson for the torus universe, offer further support for this conclusion. Currently work is in progress to study more realistic quantum gravity effects for BTZ black holes and other spacetime models.

Accretion and Outflow from a Magnetized, Neutrino Cooled Torus around the Gamma Ray Burst Central Engine

NASA Astrophysics Data System (ADS)

Janiuk, Agnieszka; Moscibrodzka, Monika

Gamma Ray Bursts (GRB) are the extremely energetic transient events, visible from the most distant parts of the Universe. They are most likely powered by accretion on the hyper-Eddington rates that proceeds onto a newly born stellar mass black hole. This central engine gives rise to the most powerful, high Lorentz factor jets that are responsible for energetic gamma ray emission. We investigate the accretion flow evolution in GRB central engine, using the 2D MHD simulations in General Relativity. We compute the structure and evolution of the extremely hot and dense torus accreting onto the fast spinning black hole, which launches the magnetized jets. We calculate the chemical structure of the disk and account for neutrino cooling. Our preliminary runs apply to the short GRB case (remnant torus accreted after NS-NS or NS-BH merger). We estimate the neutrino luminosity of such an event for chosen disk and central BH mass.

CHI during an ohmic discharge in HIT-II

NASA Astrophysics Data System (ADS)

Mueller, Dennis; Nelson, Brian A.; Redd, Aaron J.; Hamp, William T.

2004-11-01

Coaxial Helicity Injection (CHI) has been used on the National Spherical Torus Experiment (NSTX), the Helicity Injected Torus (HIT) and HIT-II to initiate plasma and to drive up to 400 kA of toroidal current. The primary goal of the CHI systems is to provide a start-up plasma with substantial toroidal current that can be heated and sustained with other methods. We have investigated the use of CHI systems to add current to an established, inductively driven plasma. This may be an attractive method to add edge current that may modify the stability characteristics of the discharge or modify the particle and energy transport in a spherical torus. For example, divertor biasing experiments have been successful in modifying particle and energy transport in the scrape-off layer of tokamaks. Use of IGBT power supplies to modulate the injector current makes analysis of current penetration feasible by comparisons of before and after CHI using EFIT analysis of the data.

Micromagnetic simulation study of magnetization reversal in torus-shaped permalloy nanorings

NASA Astrophysics Data System (ADS)

Mishra, Amaresh Chandra; Giri, R.

2017-09-01

Using micromagnetic simulation, the magnetization reversal of soft permalloy rings of torus shape with major radius R varying within 20-100 nm has been investigated. The minor radius r of the torus rings was increased from 5 nm up to a maximum value rmax such that R- rmax = 10 nm. Micromagnetic simulation of in-plane hysteresis curve of these nanorings revealed that in the case of very thin rings (r ≤ 10 nm), the remanent state is found to be an onion state, whereas for all other rings, the remanent state is a vortex state. The area of the hysteresis loop was found to be decreasing gradually with the increment of r. The normalized area under the hysteresis loops (AN) increases initially with increment of r. It attains a maximum for a certain value of r = r0 and again decreases thereafter. This value r0 increases as we decrease R and as a result, this peak feature is hardly visible in the case of smaller rings (rings having small R).

Design Features and Commissioning of the Versatile Experiment Spherical Torus (VEST) at Seoul National University

NASA Astrophysics Data System (ADS)

J. Chung, K.; H. An, Y.; K. Jung, B.; Y. Lee, H.; C., Sung; S. Na, Y.; S. Hahm, T.; S. Hwang, Y.

2013-03-01

A new spherical torus called VEST (Versatile Experiment Spherical Torus) is designed, constructed and successfully commissioned at Seoul National University. A unique design feature of the VEST is two partial solenoid coils installed at both vertical ends of a center stack, which can provide sufficient magnetic fluxes to initiate tokamak plasmas while keeping a low aspect ratio configuration in the central region. According to initial double null merging start-up scenario using the partial solenoid coils, appropriate power supplies for driving a toroidal field coil, outer poloidal field coils, and the partial solenoid coils are fabricated and successfully commissioned. For reliable start-up, a pre-ionization system with two cost-effective homemade magnetron power supplies is also prepared. In addition, magnetic and spectroscopic diagnostics with appropriate data acquisition and control systems are well prepared for initial operation of the device. The VEST is ready for tokamak plasma operation by completing and commissioning most of the designed components.

Determination of ionic abundances in the Io torus using the Hopkins Ultraviolet Telescope

NASA Technical Reports Server (NTRS)

Moos, H. W.; Feldman, P. D.; Durrance, S. T.; Blair, W. P.; Bowers, C. W.; Davidsen, A. F.; Dixon, W. V.; Henry, R. C.; Ferguson, H. C.; Kimble, R. A.

1991-01-01

Attention is given to a 415-1864-A spectrum of the emissions from the Io torus with about 3-A resolution in first order (830-1864 A) obtained with HUT in December 1990. A list of the 31 strongest features shows that, apart from five features that are totally or partially terrestrial, all are due to O(+), S(+), S(2+), and S(3+). There is no evidence for elements other than oxygen and sulfur. The spectrum shows many additional weaker emission features so that the existence of minor species cannot be ruled out at this time. Because the HUT spectrum contains well-resolved lines for all four of the major species, the mixing ratio (Ni/ne) for each one can be determined without using models of the spectral emissions, or a detailed geometric model of the torus plasma. The relative concentration of O(+) determined from the HUT observation is 38 percent less than that obtained from the Voyager UVS data.

Are Khovanov-Rozansky polynomials consistent with evolution in the space of knots?

NASA Astrophysics Data System (ADS)

Anokhina, A.; Morozov, A.

2018-04-01

R-coloured knot polynomials for m-strand torus knots Torus [ m, n] are described by the Rosso-Jones formula, which is an example of evolution in n with Lyapunov exponents, labelled by Young diagrams from R ⊗ m . This means that they satisfy a finite-difference equation (recursion) of finite degree. For the gauge group SL( N ) only diagrams with no more than N lines can contribute and the recursion degree is reduced. We claim that these properties (evolution/recursion and reduction) persist for Khovanov-Rozansky (KR) polynomials, obtained by additional factorization modulo 1 + t, which is not yet adequately described in quantum field theory. Also preserved is some weakened version of differential expansion, which is responsible at least for a simple relation between reduced and unreduced Khovanov polynomials. However, in the KR case evolution is incompatible with the mirror symmetry under the change n -→ - n, what can signal about an ambiguity in the KR factorization even for torus knots.

Mind of Its Own

NASA Technical Reports Server (NTRS)

2004-01-01

This animation shows the path the Mars Exploration Rover Spirit traveled during its 24-meter (78.7-foot) autonomous drive across the bumpy terrain at Gusev Crater, Mars, on the 39th day, or sol, of its mission. The colored data are from the rover's hazard-avoidance camera and have been reconstructed to show the topography of the land. Red areas indicate extremely hazardous terrain, and green patches denote safe, smooth ground. At the end of its drive, Spirit decided it was safer to back up then go forward. The rover is now positioned directly in front of its target, a rock dubbed Stone Council.

Generating strain signals under consideration of road surface profiles

NASA Astrophysics Data System (ADS)

Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.

2015-08-01

The current study aimed to develop the mechanism for generating strain signal utilising computer-based simulation. The strain data, caused by the acceleration, were undertaken from a fatigue data acquisition involving car movements. Using a mathematical model, the measured strain signals yielded to acceleration data used to describe the bumpiness of road surfaces. The acceleration signals were considered as an external disturbance on generating strain signals. Based on this comparison, both the actual and simulated strain data have similar pattern. The results are expected to provide new knowledge to generate a strain signal via a simulation.

Effects of Sheared Flow on Microinstabilities and Transport in Plasmas

NASA Astrophysics Data System (ADS)

H, Sanuki; K, Itoh; A, Fujisawa; J, Q. Dong

2005-02-01

Theoretical and experimental studies associated with electric field effects on the stability and transport are briefly surveyed. The effects of radial electric field on the suppression and/or enhancement of various microinstabilities such as drift waves, flute mode and temperature gradient modes are discussed. The suppression of flow shear on the electron temperature gradient mode in plasmas with slightly hollow density profiles is investigated by solving the gyrokinetic integral eigenvalue equation. Comparison between theoretical predictions and experimental observations based on the HIBP measurements with high temporal and spatial resolutions is made in bumpy tori and heliotron (CHS) devices.

Galaxy gas as obscurer - II. Separating the galaxy-scale and nuclear obscurers of active galactic nuclei

NASA Astrophysics Data System (ADS)

Buchner, Johannes; Bauer, Franz E.

2017-03-01

The 'torus' obscurer of active galactic nuclei (AGN) is poorly understood in terms of its density, sub-structure and physical mechanisms. Large X-ray surveys provide model boundary constraints, for both Compton-thin and Compton-thick levels of obscuration, as obscured fractions are mean covering factors fcov. However, a major remaining uncertainty is host-galaxy obscuration. In Paper I, we discovered a relation of {NH} ∝ M_{star }^{1/3} for the obscuration of galaxy-scale gas. Here, we apply this observational relation to the AGN population, and find that galaxy-scale gas is responsible for a luminosity-independent fraction of Compton-thin AGN, but does not produce Compton-thick columns. With the host-galaxy obscuration understood, we present a model of the remaining nuclear obscurer, which is consistent with a range of observations. Our radiation-lifted torus model consists of a Compton-thick component (fcov ∼ 35 per cent) and a Compton-thin component (fcov ∼ 40 per cent), which depends on both black hole mass and luminosity. This provides a useful summary of observational constraints for torus modellers who attempt to reproduce this behaviour. It can also be employed as a sub-grid recipe in cosmological simulations that do not resolve the torus. We also investigate host-galaxy X-ray obscuration inside cosmological, hydrodynamic simulations (Evolution and Assembly of Galaxies and their Environment; Illustris). The obscuration from ray-traced galaxy gas can agree with observations, but is highly sensitive to the chosen feedback assumptions.

NEUTRON-STAR MERGER EJECTA AS OBSTACLES TO NEUTRINO-POWERED JETS OF GAMMA-RAY BURSTS

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

Just, O.; Janka, H.-T.; Schwarz, N.

2016-01-10

We present the first special relativistic, axisymmetric hydrodynamic simulations of black hole-torus systems (approximating general relativistic gravity) as remnants of binary-neutron star (NS–NS) and neutron star–black hole (NS–BH) mergers, in which the viscously driven evolution of the accretion torus is followed with self-consistent energy-dependent neutrino transport and the interaction with the cloud of dynamical ejecta expelled during the NS–NS merging is taken into account. The modeled torus masses, BH masses and spins, and the ejecta masses, velocities, and spatial distributions are adopted from relativistic merger simulations. We find that energy deposition by neutrino annihilation can accelerate outflows with initially highmore » Lorentz factors along polar low-density funnels, but only in mergers with extremely low baryon pollution in the polar regions. NS–BH mergers, where polar mass ejection during the merging phase is absent, provide sufficiently baryon-poor environments to enable neutrino-powered, ultrarelativistic jets with terminal Lorentz factors above 100 and considerable dynamical collimation, favoring short gamma-ray bursts (sGRBs), although their typical energies and durations might be too small to explain the majority of events. In the case of NS–NS mergers, however, neutrino emission of the accreting and viscously spreading torus is too short and too weak to yield enough energy for the outflows to break out from the surrounding ejecta shell as highly relativistic jets. We conclude that neutrino annihilation alone cannot power sGRBs from NS–NS mergers.« less

A broad survey of hydraulic and mechanical safety in the xylem of conifers.

PubMed

Bouche, Pauline S; Larter, Maximilien; Domec, Jean-Christophe; Burlett, Régis; Gasson, Peter; Jansen, Steven; Delzon, Sylvain

2014-08-01

Drought-induced forest dieback has been widely reported over the last decades, and the evidence for a direct causal link between survival and hydraulic failure (xylem cavitation) is now well known. Because vulnerability to cavitation is intimately linked to the anatomy of the xylem, the main objective of this study was to better understand the xylem anatomical properties associated with cavitation resistance. An extensive data set of cavitation resistance traits and xylem anatomical properties was developed for 115 conifer species, with special attention given to the micro-morphology of bordered pits. The ratio of torus to pit aperture diameter, so-called torus overlap, increased with increasing cavitation resistance, while the flexibility of the margo does not seem to play a role, suggesting that air-seeding is located at the seal between the aspirated torus and pit aperture. Moreover, punctured tori were reported in various Pinaceae species. Species resistant to cavitation had thicker tracheid walls, while their lumen diameter (conduit size) was only slightly reduced, minimizing the impact on hydraulic conductance. The results also demonstrated (i) the existence of an indirect trade-off between hydraulic safety and mechanical strength; and (ii) a consistency between species distribution and xylem anatomy: species with a wide torus overlap and high valve effects are found in arid environments such as the Mediterranean region. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Dusty Winds in Active Galactic Nuclei: Reconciling Observations with Models

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

Hönig, Sebastian F.; Kishimoto, Makoto, E-mail: S.Hoenig@soton.ac.uk

2017-04-01

This Letter presents a revised radiative transfer model for the infrared (IR) emission of active galactic nuclei (AGNs). While current models assume that the IR is emitted from a dusty torus in the equatorial plane of the AGNs, spatially resolved observations indicate that the majority of the IR emission from ≲100 pc in many AGNs originates from the polar region, contradicting classical torus models. The new model CAT3D-WIND builds upon the suggestion that the dusty gas around the AGNs consists of an inflowing disk and an outflowing wind. Here, it is demonstrated that (1) such disk+wind models cover overall amore » similar parameter range of observed spectral features in the IR as classical clumpy torus models, e.g., the silicate feature strengths and mid-IR spectral slopes, (2) they reproduce the 3–5 μ m bump observed in many type 1 AGNs unlike torus models, and (3) they are able to explain polar emission features seen in IR interferometry, even for type 1 AGNs at relatively low inclination, as demonstrated for NGC3783. These characteristics make it possible to reconcile radiative transfer models with observations and provide further evidence of a two-component parsec-scale dusty medium around AGNs: the disk gives rise to the 3–5 μ m near-IR component, while the wind produces the mid-IR emission. The model SEDs will be made available for download.« less

Disks and cones: interferometry of the dusty and molecular material of AGN on parsec sales

NASA Astrophysics Data System (ADS)

Tristam, Konrad R. W.

2016-08-01

The central engine of Active Galactic Nuclei (AGN) is surrounded by dense molecular and dusty material on parsec scales. Typically referred to as the ""dusty torus"", this material is a key ingredient of AGN because it (1) provides the angle dependent obscuration of the central engine and (2) most likely plays an important role for the accretion of the material onto the supermassive black hole. Observations using interferometry in the infrared have, in the last ten years, resolved and characterised the thermal emission from the dust heated by the AGN beyond simple fits of the spectral energy distribution, leading to a great leap forward in our view of the dusty material surrounding AGN. In general the torus is parsec-sized, with a large scatter in extension between individual objects. Our studies have led to the surprising discovery that the dust emission is clearly separated into two distinct components: an inner disk-like emission region which is surrounded by a polar elongated emitter. I will demonstrate these discoveries using the results obtained for the Circinus galaxy, and discuss how the results for this galaxy compare to other well studied sources. While putting strong constraints on torus models, our findings are in good qualitative agreement with recent hydrodynamic simulations of AGN tori. The next big step forward can be expected from sub-mm interferometry and I will give a short glimpse at the results from our recent ALMA observations of the outer torus in the Circinus galaxy.

Are All Active Galactic Nuclei Born Equal? The Silicate Dust Mineralogy Perspective

NASA Astrophysics Data System (ADS)

Li, Aigen

Dust is the cornerstone of the unification theory of active galactic nuclei (AGNs). This theory proposes that all AGNs are essentially the same object or "born equal" but viewed from different lines of sight; much of the observed diversity arises from different viewing angles toward the central engine and a dusty toroidal structure around it. When the dusty torus is viewed face-on, both the central engine and the broad-line regions can be seen directly causing objects to appear as type 1 AGNs; when the dusty torus is viewed edge- on, the anisotropic obscuration created by the torus causes objects to appear as type 2 AGNs. It is this crucial role played by dust in the unified model of AGNs that makes understanding dust properties very important in understanding AGNs. Little is known about the dust in the circumnuclear torus of AGNs. There is evidence suggesting that the size and composition of the dust in AGNs may differ substantially from that of the Galactic interstellar dust, as reflected by the flat or "gray" extinction, and the anomalous silicate emission or absorption features observed respectively in type 1 and type 2 AGNs. The silicate feature profiles of AGNs are rather diverse in peak wavelengths, widths, strengths, and band ratios of the 18 micrometer O--Si--O feature to the 9.7 micrometer Si--O feature, suggesting that the AGN silicate grains are diverse in composition and size (or probably not "born equal"). We propose a two-year project to study the size and composition of the dust in AGNs, with special attention paid to the silicate mineralogy. We will obtain constraints on the silicate composition and size by modeling the Spitzer IRS spectra of >100 AGNs of various types. We will examine whether (and how) the silicate composition and size properties vary with the properties of an AGN (e.g. type, luminosity). This research will improve our understanding of the physical properties of the dust torus and the origin of the observed silicate emission: whether it arises mainly from the torus or from the narrow line regions. We will also provide the community with "recommended" silicate opacities for AGNs of various types. This will facilitate more detailed radiative transfer modeling of the infrared spectral energy distributions of AGNs by incorporating more realistic silicate opacities. This research supports the NASA Strategic Subgoal 3C: Discover the origin, structure, evolution, and destiny of the universe.

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

C. BARNES

Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. {omega}{sub pe} >> {Omega}{sub ce} in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition ({tau} > 2). Electron Bernstein waves (EBWs) are electrostatic waves which can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as amore » result of their large K{sub i}. This talk reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub 0} {approx} 2 kG, {approx} 10{sup 13} cm{sup -3} and T{sub e} {approx} 10 - 200 eV. Results will be presented for both direct detection of EBWs and for mode-converted EBW emission. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode-converted EBW radiation temperature was found to be {le} T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe was employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance where the mode conversion of the EBWs is expected to occur. Changes in the mode conversion efficiency may explain the observation of mode-converted EBW radiation temperatures below T{sub e}. Initial results suggest EBW emission and EBW heating are viable concepts for plasmas where {omega}{sub pe} >> {Omega}{sub ce}.« less

Deployment and Drop Test of Inflatable Aeroshell for Atmospheric Entry Capsule with using Large Scientific Balloon

NASA Astrophysics Data System (ADS)

Yamada, Kazuhiko; Suzuki, Kojiro; Honma, Naohiko; Abe, Daisuke; Makino, Hitoshi; Nagata, Yasunori; Kimura, Yusuke; Koyama, Masashi; Akita, Daisuke; Hayashi, Koichi; Abe, Takashi

A deployable and flexible aeroshell for atmospheric entry vehicles has attracted attention as an innovative space transportation system in the near future, because the large-area, low-mass aeroshell dramatically reduces aerodynamic heating and achieves a soft landing without a conventional parachute system thanks to its low ballistic coefficient. Various concepts of flexible aeroshell have been proposed in the past. Our group are researching and developing a flare-type membrane aeroshell sustained by inflatable torus. As a part of the development, a deployment and drop test of a capsule-type experimental vehicle with a 1.264-m-diameter flare-type membrane aeroshell sustained by inflatable torus was carried out using a large scientific balloon in August, 2009. The objectives of this experiment are 1) to demonstrate the remote inflation system of inflatable aeroshell, 2) to acquire aerodynamic performance of a low ballistic coefficient vehicle including an inflatable structure in subsonic region, and 3) to observe behavior and deformation of the flexible aeroshell during free flight. In this test, the inflatable aeroshell was deployed at an altitude 24.6km by radio command from ground station. After deployment, the experimental vehicle was dropped from the balloon and underwent free flight. The flight data and images of the aeroshell collected using onboard sensors were transmitted successfully during the flight by the telemetry system. The data showed that the vehicle was almost stable in free flight condition and the inflatable aeroshell was collapsed at expected altitude. This deployment and drop test was very successful and useful data for design of actual atmospheric-entry vehicles with inflatable structure was acquired as planned.

National Spherical Torus Experiment (NSTX) and Planned Research

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

Peng, Yueng Kay Martin; Ono, M.; Kaye, S.

1998-01-01

The U.S. fusion energy sciences program began in 1996 to increase emphasis on confinement concept innovation. The NSTX is being built at PPPL as a national fusion science research facility in response to this emphasis. NSTX is to test fusion science principles of the Spherical Torus (ST) plasmas, which include: (1) High plasma pressure in low magnetic field for high fusion power density, (2) Good energy confinement is a small-size plasma, (3) Nearly fully self-driven (bootstrap) plasma current, (4) Dispersed heat and particle fluxes, and (5) Plasma startup without complicated in board solenoid magnet. These properties of the ST plasma,more » if verified, would lead to possible future fusion devices of high fusion performance, small size, feasible power handling, and improved economy. The design of NSTX is depicted in a figure. The vessel will be covered fully with graphite tiles and can be baked to 350 C. Other wall condition techniques are also planned. The NSTX facilty extensively utilizes the equipment at PPPL and other reasearch institutions in collaboration. These include 6-MW High Harmonic Fast Wave (HHFW) power at {approx}30 MHz for 5 s, which will be the primary heating and current drive system following the first plasma planned for April 1999, and small ECH systems to assist breakdown for initiation. A plethora of diagnostics from TFTR and collaborators are planned. A NBI system from TFTR capable of delivering 5 MW at 80 keV for 5 s, and more powerful ECH systems are also planned for installation in 2000. The baseline plan for diagnostics systems are laid out in a figure and include: (1) Rogowski coils to measure total plasma and halo curents.« less

A compact codimension-two braneworld with precisely one brane

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

Akerblom, Nikolas; Cornelissen, Gunther; Department of Mathematics, Utrecht University

Building on earlier work on football-shaped extra dimensions, we construct a compact codimension-two braneworld with precisely one brane. The two extra dimensions topologically represent a 2-torus which is stabilized by a bulk cosmological constant and magnetic flux. The torus has positive constant curvature almost everywhere, except for a single conical singularity at the location of the brane. In contradistinction to the football-shaped case, there is no fine-tuning required for the brane tension. We also present some plausibility arguments why the model should not suffer from serious stability issues.

Gauge transformation and symmetries of the commutative multicomponent BKP hierarchy

NASA Astrophysics Data System (ADS)

Li, Chuanzhong

2016-01-01

In this paper, we defined a new multi-component B type Kadomtsev-Petviashvili (BKP) hierarchy that takes values in a commutative subalgebra of {gl}(N,{{C}}). After this, we give the gauge transformation of this commutative multicomponent BKP (CMBKP) hierarchy. Meanwhile, we construct a new constrained CMBKP hierarchy that contains some new integrable systems, including coupled KdV equations under a certain reduction. After this, the quantum torus symmetry and quantum torus constraint on the tau function of the commutative multi-component BKP hierarchy will be constructed.

Orders and dimensions for sl(2) or sl(3) module categories and boundary conformal field theories on a torus

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

Coquereaux, R.; Schieber, G.; Centro Brasileiro de Pesquisas Fisicas

2007-04-15

After giving a short description, in terms of action of categories, of some of the structures associated with sl(2) and sl(3) boundary conformal field theories on a torus, we provide tables of dimensions describing the semisimple and cosemisimple blocks of the corresponding weak bialgebras (quantum groupoids), tables of quantum dimensions and orders, and tables describing induction-restriction. For reasons of size, the sl(3) tables of induction are only given for theories with self-fusion (existence of a monoidal structure)

Making of the NSTX Facility

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

C. Neumeyer; M. Ono; S.M. Kaye

1999-11-01

The NSTX (National Spherical Torus Experiment) facility located at Princeton Plasma Physics Laboratory is the newest national fusion science experimental facility for the restructured US Fusion Energy Science Program. The NSTX project was approved in FY 97 as the first proof-of-principle national fusion facility dedicated to the spherical torus research. On Feb. 15, 1999, the first plasma was achieved 10 weeks ahead of schedule. The project was completed on budget and with an outstanding safety record. This paper gives an overview of the NSTX facility construction and the initial plasma operations.

NEUTRON RADIATION DAMAGE IN CCD CAMERAS AT JOINT EUROPEAN TORUS (JET).

PubMed

Milocco, Alberto; Conroy, Sean; Popovichev, Sergey; Sergienko, Gennady; Huber, Alexander

2017-10-26

The neutron and gamma radiations in large fusion reactors are responsible for damage to charged couple device (CCD) cameras deployed for applied diagnostics. Based on the ASTM guide E722-09, the 'equivalent 1 MeV neutron fluence in silicon' was calculated for a set of CCD cameras at the Joint European Torus. Such evaluations would be useful to good practice in the operation of the video systems. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Full toroidal imaging of non-axisymmetric plasma material interaction in the National Spherical Torus Experiment divertor.

PubMed

Scotti, Filippo; Roquemore, A L; Soukhanovskii, V A

2012-10-01

A pair of two dimensional fast cameras with a wide angle view (allowing a full radial and toroidal coverage of the lower divertor) was installed in the National Spherical Torus Experiment in order to monitor non-axisymmetric effects. A custom polar remapping procedure and an absolute photometric calibration enabled the easier visualization and quantitative analysis of non-axisymmetric plasma material interaction (e.g., strike point splitting due to application of 3D fields and effects of toroidally asymmetric plasma facing components).

Packing in protein cores

NASA Astrophysics Data System (ADS)

Gaines, J. C.; Clark, A. H.; Regan, L.; O'Hern, C. S.

2017-07-01

Proteins are biological polymers that underlie all cellular functions. The first high-resolution protein structures were determined by x-ray crystallography in the 1960s. Since then, there has been continued interest in understanding and predicting protein structure and stability. It is well-established that a large contribution to protein stability originates from the sequestration from solvent of hydrophobic residues in the protein core. How are such hydrophobic residues arranged in the core; how can one best model the packing of these residues, and are residues loosely packed with multiple allowed side chain conformations or densely packed with a single allowed side chain conformation? Here we show that to properly model the packing of residues in protein cores it is essential that amino acids are represented by appropriately calibrated atom sizes, and that hydrogen atoms are explicitly included. We show that protein cores possess a packing fraction of φ ≈ 0.56 , which is significantly less than the typically quoted value of 0.74 obtained using the extended atom representation. We also compare the results for the packing of amino acids in protein cores to results obtained for jammed packings from discrete element simulations of spheres, elongated particles, and composite particles with bumpy surfaces. We show that amino acids in protein cores pack as densely as disordered jammed packings of particles with similar values for the aspect ratio and bumpiness as found for amino acids. Knowing the structural properties of protein cores is of both fundamental and practical importance. Practically, it enables the assessment of changes in the structure and stability of proteins arising from amino acid mutations (such as those identified as a result of the massive human genome sequencing efforts) and the design of new folded, stable proteins and protein-protein interactions with tunable specificity and affinity.

Enhanced depth imaging optical coherence tomography of choroidal metastasis in 14 eyes.

PubMed

Al-Dahmash, Saad A; Shields, Carol L; Kaliki, Swathi; Johnson, Timothy; Shields, Jerry A

2014-08-01

To describe the imaging features of choroidal metastasis using enhanced depth imaging optical coherence tomography (EDI-OCT). This retrospective observational case series included 31 eyes with choroidal metastasis. Spectral domain EDI-OCT was performed using Heidelberg Spectralis HRA + OCT. The main outcome measures were imaging features by EDI-OCT. Of 31 eyes with choroidal metastasis imaged with EDI-OCT, 14 (45%) eyes displayed image detail suitable for study. The metastasis originated from carcinoma of the breast (n = 7, 50%), lung (n = 5, 36%), pancreas (n = 1, 7%), and thyroid gland (n = 1, 7%). The mean tumor basal diameter was 6.4 mm, and mean thickness was 2.3 mm by B-scan ultrasonography. The tumor location was submacular in 6 (43%) eyes and extramacular in 8 (57%) eyes. By EDI-OCT, the mean tumor thickness was 987 μm. The most salient EDI-OCT features of the metastasis included anterior compression/obliteration of the overlying choriocapillaris (n = 13, 93%), an irregular (lumpy bumpy) anterior contour (n = 9, 64%), and posterior shadowing (n = 12, 86%). Overlying retinal pigment epithelial abnormalities were noted (n = 11, 78%). Outer retinal features included structural loss of the interdigitation of the cone outer segment tips (n = 9, 64%), the ellipsoid portion of photoreceptors (n = 8, 57%), external limiting membrane (n = 4, 29%), outer nuclear layer (n = 1, 7%), and outer plexiform layer (n = 1, 7%). The inner retinal layers (inner nuclear layer to nerve fiber layer) were normal. Subretinal fluid (n = 11, 79%), subretinal lipofuscin pigment (n = 1, 7%), and intraretinal edema (n = 2, 14%) were identified. The EDI-OCT of choroidal metastasis shows a characteristic lumpy bumpy anterior tumor surface and outer retinal layer disruption with preservation of inner retinal layers.

Microglia immunophenotyping in gliomas

PubMed Central

Annovazzi, Laura; Mellai, Marta; Bovio, Enrica; Mazzetti, Samanta; Pollo, Bianca; Schiffer, Davide

2018-01-01

Microglia, once assimilated to peripheral macrophages, in gliomas has long been discussed and currently it is hypothesized to play a pro-tumor role in tumor progression. Uncertain between M1 and M2 polarization, it exchanges signals with glioma cells to create an immunosuppressive microenvironment and stimulates cell proliferation and migration. Four antibodies are currently used for microglia/macrophage identification in tissues that exhibit different cell forms and cell localization. The aim of the present work was to describe the distribution of the different cell forms and to deduce their significance on the basis of what is known on their function from the literature. Normal resting microglia, reactive microglia, intermediate and bumpy forms and macrophage-like cells can be distinguished by Iba1, CD68, CD16 and CD163 and further categorized by CD11b, CD45, c-MAF and CD98. The number of microglia/macrophages strongly increased from normal cortex and white matter to infiltrating and solid tumors. The ramified microglia accumulated in infiltration areas of both high- and low-grade gliomas, when hypertrophy and hyperplasia occur. In solid tumors, intermediate and bumpy forms prevailed and there is a large increase of macrophage-like cells in glioblastoma. The total number of microglia cells did not vary among the three grades of malignancy, but macrophage-like cells definitely prevailed in high-grade gliomas and frequently expressed CD45 and c-MAF. CD98+ cells were present. Microglia favors tumor progression, but many aspects suggest that the phagocytosing function is maintained. CD98+ cells can be the product of fusion, but also of phagocytosis. Microglia correlated with poorer survival in glioblastoma, when considering CD163+ cells, whereas it did not change prognosis in isocitrate dehydrogenase-mutant low grade gliomas. PMID:29399160

Prospects for measuring the fuel ion ratio in burning ITER plasmas using a DT neutron emission spectrometer.

PubMed

Hellesen, C; Skiba, M; Dzysiuk, N; Weiszflog, M; Hjalmarsson, A; Ericsson, G; Conroy, S; Andersson-Sundén, E; Eriksson, J; Binda, F

2014-11-01

The fuel ion ratio nt/nd is an essential parameter for plasma control in fusion reactor relevant applications, since maximum fusion power is attained when equal amounts of tritium (T) and deuterium (D) are present in the plasma, i.e., nt/nd = 1.0. For neutral beam heated plasmas, this parameter can be measured using a single neutron spectrometer, as has been shown for tritium concentrations up to 90%, using data obtained with the MPR (Magnetic Proton Recoil) spectrometer during a DT experimental campaign at the Joint European Torus in 1997. In this paper, we evaluate the demands that a DT spectrometer has to fulfill to be able to determine nt/nd with a relative error below 20%, as is required for such measurements at ITER. The assessment shows that a back-scattering time-of-flight design is a promising concept for spectroscopy of 14 MeV DT emission neutrons.

An automated approach to magnetic divertor configuration design

NASA Astrophysics Data System (ADS)

Blommaert, M.; Dekeyser, W.; Baelmans, M.; Gauger, N. R.; Reiter, D.

2015-01-01

Automated methods based on optimization can greatly assist computational engineering design in many areas. In this paper an optimization approach to the magnetic design of a nuclear fusion reactor divertor is proposed and applied to a tokamak edge magnetic configuration in a first feasibility study. The approach is based on reduced models for magnetic field and plasma edge, which are integrated with a grid generator into one sensitivity code. The design objective chosen here for demonstrative purposes is to spread the divertor target heat load as much as possible over the entire target area. Constraints on the separatrix position are introduced to eliminate physically irrelevant magnetic field configurations during the optimization cycle. A gradient projection method is used to ensure stable cost function evaluations during optimization. The concept is applied to a configuration with typical Joint European Torus (JET) parameters and it automatically provides plausible configurations with reduced heat load.

Prospects for measuring the fuel ion ratio in burning ITER plasmas using a DT neutron emission spectrometer

NASA Astrophysics Data System (ADS)

Hellesen, C.; Skiba, M.; Dzysiuk, N.; Weiszflog, M.; Hjalmarsson, A.; Ericsson, G.; Conroy, S.; Andersson-Sundén, E.; Eriksson, J.; Binda, F.

2014-11-01

The fuel ion ratio nt/nd is an essential parameter for plasma control in fusion reactor relevant applications, since maximum fusion power is attained when equal amounts of tritium (T) and deuterium (D) are present in the plasma, i.e., nt/nd = 1.0. For neutral beam heated plasmas, this parameter can be measured using a single neutron spectrometer, as has been shown for tritium concentrations up to 90%, using data obtained with the MPR (Magnetic Proton Recoil) spectrometer during a DT experimental campaign at the Joint European Torus in 1997. In this paper, we evaluate the demands that a DT spectrometer has to fulfill to be able to determine nt/nd with a relative error below 20%, as is required for such measurements at ITER. The assessment shows that a back-scattering time-of-flight design is a promising concept for spectroscopy of 14 MeV DT emission neutrons.

Low thrust vehicle concept study

NASA Technical Reports Server (NTRS)

1980-01-01

Low thrust chemical (hydrogen-oxygen) propulsion systems configured specifically for low acceleration orbit transfer of large space systems were defined. Results indicate that it is cost effective and least risk to combine the OTV and stowed spacecraft in a single 65 K Shuttle. The study shows that the engine for an optimized low thrust stage (1) does not require very low thrust; (2) 1-3 K thrust range appears optimum; (3) thrust transient is not a concern; (4) throttling probably not worthwhile; and (5) multiple thrusters complicate OTV/LSS design and aggravate LSS loads. Regarding the optimum vehicle for low acceleration missions, the single shuttle launch (LSS and expendable OTV) is most cost effective and least risky. Multiple shuttles increase diameter 20%. The space based radar structure short OTV (which maximizes space available for packaged LSS) favors use of torus tank. Propellant tank pressures/vapor residuals are little affected by engine thrust level or number of burns.

Constraining the size of the dusty torus in Active Galactic Nuclei: An Optical/Infrared Reverberation Lag Study

NASA Astrophysics Data System (ADS)

Vazquez, Billy

The dusty torus is the key component in the Active Galactic Nuclei (AGN) Unification Scheme that explains the spectroscopic differences between Seyfert galaxies of types 1 and 2. The torus dust is heated by the nuclear source and emits the absorbed energy in the infrared (IR); but because of light travel times, the torus IR emission responds to variations of the nuclear ultraviolet/optical continuum with a delay that corresponds to the size of the emitting region. The results from a mid-infrared (MIR) monitoring campaign using the Spitzer Space Telescope and optical ground-based telescopes (B and V band imaging), which spanned over 2 years and covered a sample of 12 Seyfert galaxies, are presented. The aim was to constrain the distances from the nucleus to the regions in the torus emitting at wavelengths of 3.6 microm and 4.5 microm. MIR light curves showing the variability characteristics of these AGN are presented and the effects of photometric uncertainties on the time-series analysis of the light curves are discussed. Significant variability was observed in the IR light curves of 10 of 12 objects, with relative amplitudes ranging from ˜10% to ˜100% from their mean flux. The "reverberation lags" between the 3.6 microm and 4.5 microm IR bands were determined for the entire sample and between the optical and MIR bands for NGC6418. In NGC6418, the 3.6 microm and 4.5 microm fluxes lagged behind those of the optical continuum by 47.5+2.0-1.9) days and 62.5+2.5-2.9 days, respectively. This is consistent with the inferred lower limit to the sublimation radius for pure graphite grains at T=1800 K but smaller by a factor of 2 than the lower limit for dust grains with a "standard" interstellar medium (ISM) composition. There is evidence that the lags increased following approximately by a factor of 2 increase in luminosity, consistent with an increase in the sublimation radius.

Two-Dimensional Transport Studies for the Composition and Structure of the Io Plasma Torus

NASA Technical Reports Server (NTRS)

Smyth, William H.

2003-01-01

The overall objective of this project is to investigate the roles of local and spatially extended plasma sources created by Io, plasma torus chemistry, and plasma convective and diffusive transport in producing the long-lived S(+), S(++) and O(+) radial ribbon structures of the plasma torus, their System III longitude and local-time asymmetries, their energy sources and their possible time variability. To accomplish this objective, two-dimensional [radial (L) and System III longitude] plasma transport equations for the flux-tube plasma content and energy content will be solved that include the convective motions for both the east-west electric field and co-rotational velocity-lag profile near Io s orbit, radial diffusion, and the spacetime dependent flux-tube production and loss created by both neutral-plasma and plasma-ion reaction chemistry in the plasma torus. For neutral-plasma chemistry, the project will for the first time undertake the calculation of realistic three-dimensional, spatially-extended, and time-varying contributions to the flux-tube ion-production and loss that are produced by Io's corona and extended neutral clouds. The unknown two-dimensional spatial nature of diffusion in the plasma transport will be isolated and better defined in the investigation by the collective consideration of the foregoing different physical processes. For energy transport, the energy flow from hot pickup ions (and a new electron source) to thermal ions and electrons will be included in investigating the System III longitude and local-time temperature asymmetries in the plasma torus. The research is central to the scope of the NASA Sun-Earth Connection Roadmap in Quest II Campaign 4 "Comparative Planetary Space Environments" by addressing key questions for understanding the magnetosphere of planets with high rotation rates and large internal plasma sources and, in addition, is of considerable importance to the NASA Solar System Exploration Science Theme. In this regard, Jupiter is the most extreme example with its rapid rotation and with its inner Galilean satellite Io providing the dominant plasma source for the magnetosphere.

LAD Dissertation Prize: Laboratory Identification of Magnetohydrodynamic Eruption Criteria in the Solar Corona

NASA Astrophysics Data System (ADS)

Myers, Clayton E.; Yamada, Masaaki; Ji, Hantao

2018-06-01

Ideal magnetohydrodynamic instabilities such as the kink and torus instabilities are believed to play an important role in driving storage-and-release eruptions in the solar corona. These instabilities act on long-lived, arched magnetic flux ropes that are line-tied to the solar surface. In spite of numerous observational and computational studies, the conditions under which these instabilities produce an eruption remain a subject of intense debate. In this paper, we use a line-tied, arched flux rope experiment to systematically study storage-and-release eruption mechanisms in the laboratory [1]. Thin in situ magnetic probes facilitate the study of both the equilibrium and the stability of these laboratory flux ropes. In particular, they permit the direct measurement of magnetic (J×B) forces, both in equilibrium [2] and during dynamic events [3, 4]. Regarding stability and eruptions, two major results are reported: First, a new stability regime is identified where torus-unstable flux ropes fail to erupt. In this ‘failed torus’ regime, the flux rope is torus-unstable but kink-stable. Under these conditions, a dynamic toroidal field tension force surges in magnitude and prevents the flux rope from erupting [3, 4]. This dynamic tension force, which is missing from existing eruption models, is generated by magnetic self-organization events within the line-tied flux rope. Second, a clear torus instability threshold is observed in the kink-unstable regime. This latter result, which is consistent with existing theoretical [5] and numerical [6] results, verifies the key role of the torus instability in driving flux rope eruptions in the solar corona.[1] C. E. Myers, Ph.D. Thesis, Princeton University (2015)[2] C. E. Myers et al., Phys. Plasmas 23, 112102 (2016)[3] C. E. Myers et al., Nature 528, 526 (2015)[4] C. E. Myers et al., Plasma Phys. Control. Fusion 59, 014048 (2017)[5] O. Olmedo & J. Zhang, Astrophys. J. 718, 433 (2010)[6] T. Török & B. Kliem, Astrophys. J. 630, L97 (2005)This research is supported by DoE Contract DE-AC02-09CH11466 and by the NSF/DoE Center for Magnetic Self-Organization (CMSO).

High energy power-law tail in X-ray binaries and bulk Comptonization due to an outflow from a disk

NASA Astrophysics Data System (ADS)

Kumar, Nagendra

2018-02-01

We study the high energy power-law tail emission of X-ray binaries (XRBs) by a bulk Comptonization process which is usually observed in the very high soft (VHS) state of black hole (BH) XRBs and the high soft (HS) state of the neutron star (NS) and BH XRBs. Earlier, to generate the power-law tail in bulk Comptonization framework, a free-fall converging flow into BH or NS had been considered as a bulk region. In this work, for a bulk region we consider mainly an outflow geometry from the accretion disk which is bounded by a torus surrounding the compact object. We have two choices for an outflow geometry: (i) collimated flow and (ii) conical flow of opening angle θ _b and the axis is perpendicular to the disk. We also consider an azimuthal velocity of the torus fluids as a bulk motion where the fluids are rotating around the compact object (a torus flow). We find that the power-law tail can be generated in a torus flow having large optical depth and bulk speed (>0.75 c), and in conical flow with θ _b > ˜ 30° for a low value of Comptonizing medium temperature. Particularly, in conical flow the low opening angle is more favourable to generate the power-law tail in both the HS state and the VHS state. We notice that when the outflow is collimated, then the emergent spectrum does not have power-law component for a low Comptonizing medium temperature.

[Prevalence and clinical characteristics of oral bony outgrowth in a Moroccan population].

PubMed

Oualalou, Y; Azaroual, M F; Zaoui, F; Chbicheb, S; Berrada, S

2014-11-01

Oral bony outgrowths (OBOs) are localized bony protuberances that arise from the cortical plate. Various types of OBOs have been described, the precise designation of which depends on anatomic location such as torus palatinus, torus mandibularis, buccal exostosis, or palatal exostosis. We had for aim to determine the prevalence and clinical characteristics of OBOs in a Moroccan population. This cross-sectional study was conducted between March 15 and June 30, 2011 at the Rabat-Salé teaching hospital dental consultation and treatment center, in Morocco. Three hundred and fifty-three patients (160 female and 193 male patients), 11 to 82 years of age, were examined clinically and radiologically to determine the presence of OBO. Twenty-four patients (6.8%) presented with OBOs. The prevalence for exostosis, torus mandibularis, torus palatinus, and associated OBOs was 3.1%, 2%, 0.8%, and 0.9% respectively. There was a significant difference (P=0,01) between the average age for patients presenting with OBO (43.2±12 years of age) and the average age for patients without any OBO (36.5±16 years of age). The prevalence of OBOs in female patients (7.3%) was higher than in male patients (6.3%) but the difference was not significant (P=0.439). Patients with occlusal parafunctional activity presented with significantly more OBO (P=0.016). The reported prevalence of OBO is extremely variable, according to age, gender, and ethnic group. The occurrence of OBO could be triggered by genetic factors associated with environmental factors. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Photoevaporation of Dusty Clouds near Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Pier, Edward A.; Voit, G. Mark

1995-09-01

We investigate the hydrodynamic and line-emitting properties of dusty clouds exposed to an active galactic nucleus (AGN) continuum. Such clouds may be found on the inner edges of the tori commonly implicated in AGN unification schemes. An X-ray-heated wind will be driven off the surface of such a cloud, eventually destroying it. Dust grains are carried along with the flow and are destroyed by sputtering as the wind heats. In smaller clouds, sputtering regulates the outflow by reducing the radiation force opposing the flow. Cloud evaporation may be fast enough to determine the location of the inner edge of the torus. However, since the evaporation time is much longer than the orbital time, clouds on eccentric orbits can penetrate well inside the inner edge of the torus. Therefore, the ionization structure of the cloud is determined only by the incipient continuum shape. The inner faces of exposed clouds are pressurized primarily by the incident radiation. Radiation pressure on dust grains regulates how gas pressure increases with optical depth. Ionization levels decrease inward, and the bulk of the cloud is molecular and neutral. The effects of dust extinction and high density suppress the hydrogen recombination lines and the forbidden lines from C, N, and 0 ions below observed levels despite the high covering factor expected for the torus. However, the inner edge of the torus is a natural place for producing the iron coronal lines often seen in the spectra of AGNs (i.e., [Fe VII] λ6087, [Fe X] λ6375, [Fe XI] λ7892, and [Fe XIV] λ5303).

Study of Swift/Bat Selected Low-luminosity Active Galactic Nuclei Observed with Suzaku

NASA Astrophysics Data System (ADS)

Kawamuro, Taiki; Ueda, Yoshihiro; Tazaki, Fumie; Terashima, Yuichi; Mushotzky, Richard

2016-11-01

We systematically analyze the broadband (0.5-200 keV) X-ray spectra of hard X-ray (>10 keV) selected local low-luminosity active galactic nuclei (LLAGNs) observed with Suzaku and Swift/BAT. The sample consists of 10 LLAGNs detected with Swift/BAT with intrinsic 14-195 keV luminosities smaller than 1042 erg s-1 available in the Suzaku archive, covering a wide range of the Eddington ratio from 10-5 to 10-2. The overall spectra can be reproduced with an absorbed cut-off power law, often accompanied by reflection components from distant cold matter, and/or optically thin thermal emission from the host galaxy. In all of the objects, relativistic reflection components from the innermost disk are not required. Eight objects show a significant narrow iron-Kα emission line. Comparing their observed equivalent widths with the predictions from the Monte-Carlo-based torus model by Ikeda et al. (2009), we constrain the column density in the equatorial plane to be {log} {N}{{H}}{{eq}}\\gt 22.7, or the torus half-opening angle θ oa < 70°. We infer that the Eddington ratio (λ Edd) is a key parameter that determines the torus structure of LLAGNs: the torus becomes large at λ Edd ≳ 2 × 10-4, whereas at lower accretion rates it is little developed. The luminosity correlation between the hard X-ray and mid-infrared (MIR) bands of the LLAGNs follows the same correlation as for more luminous AGNs. This implies that mechanisms other than AGN-heated dust are responsible for the MIR emission in low Eddington ratio LLAGNs.

Free-Free Absorption on Parsec Scales in Seyfert Galaxies

NASA Astrophysics Data System (ADS)

Roy, A. L.; Ulvestad, J. S.; Wilson, A. S.; Colbert, E. J. M.; Mundell, C. G.; Wrobel, J. M.; Norris, R. P.; Falcke, H.; Krichbaum, T.

Seyfert galaxies come in two main types (types 1 and 2) and the difference is probably due to obscuration of the nucleus by a torus of dense molecular material. The inner edge of the torus is expected to be ionized by optical and ultraviolet emission from the active nucleus, and will radiate direct thermal emission (e.g. NGC 1068) and will cause free-free absorption of nuclear radio components viewed through the torus (e.g. Mrk 231, Mrk 348, NGC 2639). However, the nuclear radio sources in Seyfert galaxies are weak compared to radio galaxies and quasars, demanding high sensitivity to study these effects. We have been making sensitive phase referenced VLBI observations at wavelengths between 21 and 2 cm where the free-free turnover is expected, looking for parsec-scale absorption and emission. We find that free-free absorption is common (e.g. in Mrk 348, Mrk 231, NGC 2639, NGC 1068) although compact jets are still visible, and the inferred density of the absorber agrees with the absorption columns inferred from X-ray spectra (Mrk 231, Mrk 348, NGC 2639). We find one-sided parsec-scale jets in Mrk 348 and Mrk 231, and we measure low jet speeds (typically £ 0.1 c). The one-sidedness probably is not due to Doppler boosting, but rather is probably free-free absorption. Plasma density required to produce the absorption is Ne 3 2 105 cm-3 assuming a path length of 0.1 pc, typical of that expected at the inner edge of the obscuring torus.

VARIABLE REDDENING AND BROAD ABSORPTION LINES IN THE NARROW-LINE SEYFERT 1 GALAXY WPVS 007: AN ORIGIN IN THE TORUS

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

Leighly, Karen M.; Cooper, Erin; Grupe, Dirk

2015-08-10

We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ∼2010 accompanied by flattening of the optical and UV photometry that suggests variable reddening. Analysis of four Hubble Space Telescope COS observations since 2010, including a Director’s Discretionary time observation during the occultation, shows that the broad-absorption-line velocity offset and the C iv emission-line width both decrease as the reddeningmore » increases. The occultation dynamical timescale, the BAL variability dynamical timescale, and the density of the BAL gas show that both the reddening material and the broad-absorption-line gas are consistent with an origin in the torus. These observations can be explained by a scenario in which the torus is clumpy with variable scale height, and the BAL gas is blown from the torus material like spray from the crest of a wave. As the obscuring material passes into our line of sight, we alternately see high-velocity broad absorption lines and a clear view to the central engine, or low-velocity broad absorption lines and strong reddening. WPVS 007 has a small black hole mass, and correspondingly short timescales, and so we may be observing behavior that is common in BALQSOs, but is not typically observable.« less

Groundbased IO [O I] 6300A Observations during the Galileo I24 and I25 and Cassini Encounters

NASA Technical Reports Server (NTRS)

Oliverson, R. J.; Morgenthaler, J. P.; Scherb, F.; Harris, W. M.; Smyth, W. H.; Lupie, O. L.; Oegerle, William R. (Technical Monitor)

2002-01-01

We report on selected recent spectroscopic observations of Io [OI] 6300Angstrom emission, using the high-resolution (R approximately equal to 120,000) stellar spectrograph at the National Solar Observatory McMath-Pierce telescope. These data were obtained during the Galileo I24 (1999-Oct-11) and I25 (1999-Nov-26) encounters with Io and the Cassini Jupiter encounter (closest approach 2000-Dec-30). The exposure time for each spectrum was 15 minutes, with a 5.2 second x 5.2 second aperture centered on Io. We obtained 102 spectra for the I24 encounter during 1999 October 9-13, 82 spectra for the I25 encounter during 1999 November 24-28, 313 spectra during 2000 December 11-23, and 280 spectra during 2000 December 29-2001 January 21 for the Cassini Jupiter encounter. We showed in a recent paper (Oliversen et al. 2001, JGR, 106, 26183) that this emission allows us to use Io as a localized probe of the three-dimensional plasma torus structure. We will also present preliminary results on selected contemporaneous narrowband [SII]6731A torus images obtained at the McMath-Pierce west auxiliary telescope. We took 136, 112, and 277 torus images during the Galileo I24, Galileo I25 and Cassini Jupiter encounters, respectively. Jupiter was imaged directly onto the CCD through a ND 4 filter and the reflected light was used for guiding. Both sides of the torus were imaged simultaneously when there were no Galilean satellites between 3-8 Jovian radii from Jupiter.

Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

NASA Astrophysics Data System (ADS)

Wang, Tinggui; Ferland, Gary J.; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

2016-06-01

Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe II emission lines: strong UV Fe II UV arising from transitions to ground/low excitation levels, and very weak Fe II at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C IV, Al III and Mg II but sometimes, a lack of non-resonant lines such as C III], S III and He II. We interpret the Fe II lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 Å produces Fe II emission very similar to that observed. The gas is too cool to collisionally excite Fe II lines, accounting for the lack of optical emission. The spectral energy distribution from the UV to the mid-infrared can be modeled as emission from a clumpy dusty torus, with UV emission being reflected/scattered light either by the dusty torus or the outflow. Within this scenario, we estimate a minimum covering factor of the outflows from a few to 20% for the Fe II scattering region, suggesting that Fe II BAL quasars are at a special stage of quasar evolution.

Modeling Enceladus and its torus in Saturn's magnetosphere (Invited)

NASA Astrophysics Data System (ADS)

Jia, Y.; Russell, C. T.; Khurana, K. K.; Gombosi, T. I.

2010-12-01

The dynamics of the saturnian magnetosphere is controlled by the planetary spin at a rate of about 10.5 hours. The second icy moon of Saturn, Enceladus, orbits at 4 planetary radii deep in the inner magnetosphere. Enceladus creates neutrals at a rate of hundreds of kilograms per second. These neutrals are ionized and picked up by the ambient plasma and spun up to the corotational velocity to form a plasma disk. Consequently, the gas and plasma density peak close to the Enceladus orbit. In the gas torus, the majority of the gas particles travel at their keplerian speed of 14 km/s, while the bulk of the plasma rotates at 30-40 km/s as a response to the rigid spinning of the saturnian magnetic field. The corotating plasma torus feels a centrifugal force that is balanced by the magnetic tension force. To balance the centripetal force of this plasma disk, Saturn’s magnetic field is stretched in both radial and azimuthal directions. At Enceladus the massive pickup of new ions from its plume slows down the corotating flow and breaks this force balance to cause plasma flows in the radial direction of Saturn. Such radial flows in the inner magnetosphere of Saturn are supported by Cassini observations using various particle and field instruments. In this study we summarize the lessons learned from recent Cassini observations and our numerical simulation effort of the local interactions at Enceladus, and model the inner magnetosphere of Saturn to reproduce the force balance processes. The neutral torus is treated as a background in this axis-symmetric model.

Ice as a Construction Material

NASA Technical Reports Server (NTRS)

Zuppero, Anthony; Lewis, J.

1998-01-01

This presentation shows how water and ice can enable exceptionally simple ways to construct structures in deep space. Practicality is underscored by applying advanced tank methods being developed for Mars missions. Water or ice is now known to be present or abundant on most objects in the solar system, starting with the planet Mercury. Thermal processes alone can be used to melt ice . The cold of space can refreeze water back into ice. The anomalous low vapor pressure of water, about 7 mm Hg, permits bladder containers. Tanks or bladders made with modern polymer fiber and film can exhibit very small (<0.1 %) equivalent tankage and ullage fractions and thus hold thousands of tons of water per ton bladder. Injecting water into a bladder whose shape when inflated is the desired final shape, such as a space vehicle, provides a convenient way to construct large structures. In space, structures of 1O,OOO-T mass become feasible because the bladder mass is low enough to be launched. The bladder can weigh 1OOO times less than its contents, or 10 T. The bladder would be packed like a parachute. Shaped memory materials and/or gas inflation could reestablish the desired structure shape after unpacking. The water comes from space resources. An example examines construction of torus space vehicle with 100-m nominal dimension. People would live inside the torus. A torus, like a tire on an automobile, would spin and provide synthetic gravity at its inner surface. A torus of order 100 m across would provide a gravity with gradients low enough to mitigate against vertigo.

Nobody’s perfect: can irregularities in pit structure influence vulnerability to cavitation?

PubMed Central

Plavcová, Lenka; Jansen, Steven; Klepsch, Matthias; Hacke, Uwe G.

2013-01-01

Recent studies have suggested that species-specific pit properties such as pit membrane thickness, pit membrane porosity, torus-to-aperture diameter ratio and pit chamber depth influence xylem vulnerability to cavitation. Despite the indisputable importance of using mean pit characteristics, considerable variability in pit structure within a single species or even within a single pit field should be acknowledged. According to the rare pit hypothesis, a single pit that is more air-permeable than many neighboring pits is sufficient to allow air-seeding. Therefore, any irregularities or morphological abnormalities in pit structure allowing air-seeding should be associated with increased vulnerability to cavitation. Considering the currently proposed models of air-seeding, pit features such as rare, large pores in the pit membrane, torus extensions, and plasmodesmatal pores in a torus can represent potential glitches. These aberrations in pit structure could either result from inherent developmental flaws, or from damage caused to the pit membrane by chemical and physical agents. This suggests the existence of interesting feedbacks between abiotic and biotic stresses in xylem physiology. PMID:24273549

Energetic neutral particles from Jupiter and Saturn

NASA Astrophysics Data System (ADS)

Cheng, A. F.

1986-04-01

The Voyager 1 spacecraft has detected energetic neutral particles escaping from the magnetospheres of Jupiter and Saturn. These energetic neutrals are created in charge exchange reactions between radiation belt ions and ambient atoms or molecules in the magnetosphere. If the Io torus is assumed to be the dominant Jovian source region for energetic neutrals, the Voyager observations can be used to infer upper limits to the average ion intensities there below about 200 keV. No readily interpretable in-situ measurements are available in the Io torus at these energies. The middle and outer Jovian magnetospheres may also be a significant source of energetic neutrals. At Saturn, the observed neutral particle count rates are too high to be explained by charge exchange between fast protons and H atoms of the Titan torus. Most of the energetic neutrals may be produced by charge exchanges between heavy ions and a neutral cloud containing H2O in Saturn's inner magnetosphere. If so, the Voyager measurements of energetic neutral fluxes would be the first detected emissions from this region of Saturn's magnetosphere.

Ultrasoft x-ray imaging system for the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Stutman, D.; Finkenthal, M.; Soukhanovskii, V.; May, M. J.; Moos, H. W.; Kaita, R.

1999-01-01

A spectrally resolved ultrasoft x-ray imaging system, consisting of arrays of high resolution (<2 Å) and throughput (⩾tens of kHz) miniature monochromators, and based on multilayer mirrors and absolute photodiodes, is being designed for the National Spherical Torus Experiment. Initially, three poloidal arrays of diodes filtered for C 1s-np emission will be implemented for fast tomographic imaging of the colder start-up plasmas. Later on, mirrors tuned to the C Lyα emission will be added in order to enable the arrays to "see" the periphery through the hot core and to study magnetohydrodynamic activity and impurity transport in this region. We also discuss possible core diagnostics, based on tomographic imaging of the Lyα emission from the plume of recombined, low Z impurity ions left by neutral beams or fueling pellets. The arrays can also be used for radiated power measurements and to map the distribution of high Z impurities injected for transport studies. The performance of the proposed system is illustrated with results from test channels on the CDX-U spherical torus at Princeton Plasma Physics Laboratory.

Coulomb thermal properties and stability of the Io plasma torus

NASA Technical Reports Server (NTRS)

Barbosa, D. D.; Coroniti, F. V.; Eviatar, A.

1983-01-01

Coulomb collisional energy exchange rates are computed for a model of the Io plasma torus consisting of newly created pickup ions, a background of thermally degraded intermediary ions, and a population of cooler electrons. The electrons are collisionally heated by both the pickup ions and background ions and are cooled by electron impact excitation of plasma ions which radiate in the EUV. It is found that a relative concentration of S III pickup ions forbidden S III/electrons = 0.1 with a temperature of 340 eV can deliver energy to the electrons at a rate of 3 x 10 to the -13th erg/cu cm per sec, sufficient to power the EUV emissions in the Io torus. The model predicts a background ion temperature Ti of about 53 eV and an electron temperature Te of about 5.5 eV on the basis of steady-state energy balance relations at Coulomb rates. The model also predicts electron temperature fluctuations at the 30 percent level on a time scale of less than 11 hours, consistent with recent observations of this phenomenon.

Laboratory Evidence That Line-Tied Toroidal Magnetic Fields Can Suppress Loss-of-Equilibrium Flux Rope Eruptions in the Solar Corona

NASA Astrophysics Data System (ADS)

Myers, C. E.; Yamada, M.; Belova, E.; Ji, H.; Yoo, J.; Fox, W. R., II; Jara-Almonte, J.

2014-12-01

Loss-of-equilibrium mechanisms such as the ideal torus instability [Kliem & Török, Phys. Rev. Lett. 96, 255002 (2006)] are predicted to drive arched flux ropes in the solar corona to erupt. In recent line-tied flux rope experiments conducted in the Magnetic Reconnection Experiment (MRX), however, we find that quasi-statically driven flux ropes remain confined well beyond the predicted torus instability threshold. In order to understand this behavior, in situ measurements from a 300 channel 2D magnetic probe array are used to comprehensively analyze the force balance between the external (potential) and internal (plasma-generated) magnetic fields. We find that forces due to the line-tied toroidal magnetic field, which are not included in the basic torus instability theory, can play a major role in preventing eruptions. The dependence of these toroidal magnetic forces on various potential field and flux rope parameters will be discussed. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the NSF/DoE Center for Magnetic Self-Organization (CMSO).

Laboratory evidence that line-tied tension forces can suppress loss-of-equilibrium flux rope eruptions in the solar corona

NASA Astrophysics Data System (ADS)

Myers, C. E.; Yamada, M.; Belova, E.; Ji, H.; Yoo, J.; Fox, W.; Jara-Almonte, J.; Gao, L.

2014-10-01

Loss-of-equilibrium mechanisms such as the ideal torus instability [Kliem & Török, Phys. Rev. Lett. 96, 255002 (2006)] are predicted to drive arched flux ropes in the solar corona to erupt. In recent line-tied flux rope experiments conducted in the Magnetic Reconnection Experiment (MRX), however, we find that quasi-statically driven flux ropes remain confined well beyond the predicted torus instability threshold. In order to understand this behavior, in situ measurements from a 300 channel 2D magnetic probe array are used to comprehensively analyze the force balance between the external (vacuum) and internal (plasma-generated) magnetic fields. We find that the line-tied tension force--a force that is not included in the basic torus instability theory--plays a major role in preventing eruptions. The dependence of this tension force on various vacuum field and flux rope parameters will be discussed. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the NSF/DoE Center for Magnetic Self-Organization (CMSO).

Hypercat - Hypercube of AGN tori

NASA Astrophysics Data System (ADS)

Nikutta, Robert; Lopez-Rodriguez, Enrique; Ichikawa, Kohei; Levenson, Nancy A.; Packham, Christopher C.

2018-06-01

AGN unification and observations hold that a dusty torus obscures the central accretion engine along some lines of sight. SEDs of dust tori have been modeled for a long time, but resolved emission morphologies have not been studied in much detail, because resolved observations are only possible recently (VLTI,ALMA) and in the near future (TMT,ELT,GMT). Some observations challenge a simple torus model, because in several objects most of MIR emission appears to emanate from polar regions high above the equatorial plane, i.e. not where the dust supposedly resides.We introduce our software framework and hypercube of AGN tori (Hypercat) made with CLUMPY (www.clumpy.org), a large set of images (6 model parameters + wavelength) to facilitate studies of emission and dust morphologies. We make use of Hypercat to study the morphological properties of the emission and dust distributions as function of model parameters. We find that a simple clumpy torus can indeed produce 10-micron emission patterns extended in polar directions, with extension ratios compatible with those found in observations. We are able to constrain the range of parameters that produce such morphologies.

Design and Construction of Versatile Experiment Spherical Torus (VEST) at Seoul National University

NASA Astrophysics Data System (ADS)

An, Younghwa; Chung, Kyoung-Jae; Jung, Bongki; Lee, Hyunyeong; Sung, Choongki; Kim, Hyun-Seok; Na, Yong-Su; Hwang, Yong-Seok

2011-10-01

A new spherical torus, named as VEST (Versatile Experiment Spherical Torus), has been built at Seoul National University to investigate versatile research topics such as double null merging start-up, divertor engineering and non-inductive current drive. VEST is characterized by two partial solenoid coils installed at both vertical ends of a center stack, which will be used for double null merging start-up schemes. A poloidal field (PF) coil system including the partial solenoids for break-down and a long solenoid for the sustainment of merged plasma has been designed by solving circuit equations for the PF coils and vacuum vessel elements in consideration of required volt-second, null configuration and eddy current. To supply required currents to the PF coils and solenoids, power supplies based on double-swing circuit have been designed and fabricated with capacitor banks and thyristor switch assemblies. Also a power supply utilizing cost-effective commercial batteries has been developed for toroidal field(TF) coils. Detailed descriptions on the design of VEST and some initial test results will be presented.

Hopkins Ultraviolet Telescope determination of the Io torus electron temperature

NASA Technical Reports Server (NTRS)

Hall, D. T.; Bednar, C. J.; Durrance, S. T.; Feldman, P. D.; Mcgrath, M. A.; Moos, H. W.; Strobel, D. F.

1994-01-01

Sulfur ion emissions from the Io plasma torus observed by the Hopkins Ultraviolet Telescope (HUT) in 1990 December have been analyzed to determine the effective temperature of the exciting electrons. Spectra were obtained with a long slit that extended from 3.1 to 8.7 Jupiter radii R(sub J) on both dawn and dusk torus ansae. The average temperature of electrons exciting S(2+) emissions from the dawn ansa is (4800 +/- 2400) K lower than on the dusk ansa, a dawn-dusk asymmetry comparable in both sign and magnitude to that measured by the Voyager Ultraviolet Spectrograph (UVS) experiment. Emissions from S(2+) ions are generated in a source region with electron temperatures in the range 32,000-56,000 K; S(3+) ion emissions are excited by electrons that average 20,000-40,000 K hotter. This distinct difference suggests that the S(3+) emission source region is spatially separate from the S(2+) source region. Estimated relative aperture filling factors suggest that the S(3+) emissions originate from a region more extended out of the centrifugal plane than the S(2+) emissions.

A Comparative Study between a Failed and a Successful Eruption Initiated from the Same Polarity Inversion Line in AR 11387

NASA Astrophysics Data System (ADS)

Liu, Lijuan; Wang, Yuming; Zhou, Zhenjun; Dissauer, Karin; Temmer, Manuela; Cui, Jun

2018-05-01

In this paper, we analyzed a failed and a successful eruption that initiated from the same polarity inversion line within NOAA AR 11387 on 2011 December 25. They both started from a reconnection between sheared arcades, with distinct pre-eruption conditions and eruption details: before the failed one, the magnetic fields of the core region had a weaker non-potentiality; the external fields had a similar critical height for torus instability, and a similar local torus-stable region, but a larger magnetic flux ratio (of low corona and near-surface region) compared to the successful one. During the failed eruption, a smaller Lorentz force impulse was exerted on the outward ejecta; the ejecta had a much slower rising speed. Factors that might lead to the initiation of the failed eruption are identified: (1) a weaker non-potentiality of the core region, and a smaller Lorentz force impulse gave the ejecta a small momentum; (2) the large flux ratio, and the local torus-stable region in the corona provided strong confinements that made the erupting structure regain an equilibrium state.

4d $$ \\mathcal{N}=1 $$ from 6d $$ \\mathcal{N}=\\left(1,0\\right) $$ on a torus with fluxes

DOE PAGES

Bah, Ibrahima; Hanany, Amihay; Maruyoshi, Kazunobu; ...

2017-06-05

Compactifying N = (1, 0) theories on a torus, with additional fluxes for global symmetries, we obtain N = 1 supersymmetric theories in four dimensions. It is shown that for many choices of flux these models are toric quiver gauge theories with singlet fields. Particularly we compare the anomalies deduced from the description of the six dimensional theory and the anomalies of the quiver gauge theories. Also, we give predictions for anomalies of four-dimensional theories corresponding to general compactifi cations of M5-branes probing C 2/Z k singularities.

Effects of a vertical magnetic field on particle confinement in a magnetized plasma torus.

PubMed

Müller, S H; Fasoli, A; Labit, B; McGrath, M; Podestà, M; Poli, F M

2004-10-15

The particle confinement in a magnetized plasma torus with superimposed vertical magnetic field is modeled and measured experimentally. The formation of an equilibrium characterized by a parallel plasma current canceling out the grad B and curvature drifts is described using a two-fluid model. Characteristic response frequencies and relaxation rates are calculated. The predictions for the particle confinement time as a function of the vertical magnetic field are verified in a systematic experimental study on the TORPEX device, including the existence of an optimal vertical field and the anticorrelation between confinement time and density.

Hole growth dynamics in a two dimensional Leidenfrost droplet

NASA Astrophysics Data System (ADS)

Raufaste, Christophe; Celestini, Franck; Barzyk, Alexandre; Frisch, Thomas

2015-03-01

We studied the behaviors of Leidenfrost droplets confined in a Hele-Shaw cell. These droplets are unstable above a critical size and a hole grows at their center. We experimentally investigate two different systems for which the hole growth dynamics exhibits peculiar features that are driven by capillarity and inertia. We report a first regime characterized by the liquid reorganization from a liquid sheet to a liquid torus with similarities to the burst of micron-thick soap films. In the second regime, the liquid torus expands and thins before fragmentation. Finally, we propose models to account for the experimental results.

Rotation sets and phase-locking in an electronic three oscillator system

NASA Astrophysics Data System (ADS)

Ashwin, Peter; Guaschi, John; Phelps, J. M.

1993-07-01

The parameter space of an electronic three oscillator system is investigated and various codimension one and two bifurcations predicted by Baesens, Guckenheimer, Kim and MacKay are identified. Sampled time-series from the experimental systems are recorded and analysed for partial mode-locking or resonance (one or two independent rational relations between the average rates of change of the angles describing the system) using knowledge of where the invariant torus lies and the torus unfolding scheme of Ashwin and Swift. Examples of toroidal and annular chaos are investigated by finding bounds on the size and shape of the rotation set.

Hydrodynamic collimation of gamma-ray-burst fireballs

PubMed

Levinson; Eichler

2000-07-10

Analytic solutions are presented for the hydrodynamic collimation of a relativistic fireball by a surrounding baryonic wind emanating from a torus. The opening angle is shown to be the ratio of the power output of the inner fireball to that of the exterior baryonic wind. The gamma ray burst 990123 might thus be interpreted as a baryon-poor jet (BPJ) with an energy output of order 10(50) erg or less, collimated by a baryonic wind from a torus with an energy output of order 10(52.5) erg, roughly the geometric mean of the BPJ and its isotropic equivalent.

Goose-skin Pleura: A Thoracoscopic Finding in a Case of Recurrent Undiagnosed Pleural Effusion.

PubMed

Al-Halfawy, Ahmed; Light, Richard W

2010-10-01

We present the case of a female patient who presented with undiagnosed pleural effusion. Thoracoscopy was performed and at the beginning of the procedure, the parietal pleura was rather uniformly congested but with a smooth surface. As time passed, the parietal pleura became roughened by bumpy areas of mucosal elevations, which looked soft and watery. This became evident during the biopsy procedure, as the pleura was markedly edematous. The biopsy specimens were nonspecific and the cause of the effusion remained unclear. This phenomenon, which we termed "goose-skin" pleura, showed that the origin of the pleural effusion formed was the parietal pleura, for unknown causes.

Population-wide sodium reduction: The bumpy road from evidence to policy

PubMed Central

Appel, Lawrence J; Angell, Sonia Y; Cobb, Laura K; Limper, Heather; Nelson, David E.; Samet, Jonathan M; Brownson, Ross C.

2016-01-01

Elevated blood pressure is a highly prevalent condition that is etiologically related to coronary heart disease and stroke, two of the leading causes of morbidity and mortality throughout the world. Excess salta (sodium chloride) intake is a major determinant of elevated blood pressure. In this paper we discuss the scientific rationale for population-wide salt reduction, the types and strength of available evidence, policy-making on dietary salt in the United States and other countries, and the role and impact of key stakeholders. We highlight a number of lessons learned, many of which are germane to policy development in other domains. PMID:22626000

Test Structures For Bumpy Integrated Circuits

NASA Technical Reports Server (NTRS)

Buehler, Martin G.; Sayah, Hoshyar R.

1989-01-01

Cross-bridge resistors added to comb and serpentine patterns. Improved combination of test structures built into integrated circuit used to evaluate design rules, fabrication processes, and quality of interconnections. Consist of meshing serpentines and combs, and cross bridge. Structures used to make electrical measurements revealing defects in design or fabrication. Combination of test structures includes three comb arrays, two serpentine arrays, and cross bridge. Made of aluminum or polycrystalline silicon, depending on material in integrated-circuit layers evaluated. Aluminum combs and serpentine arrays deposited over steps made by polycrystalline silicon and diffusion layers, while polycrystalline silicon versions of these structures used to cross over steps made by thick oxide layer.

Gamma-ray bursts from accreting black holes in neutron star mergers

NASA Astrophysics Data System (ADS)

Ruffert, M.; Janka, H.-Th.

1999-04-01

By means of three-dimensional hydrodynamic simulations with a Eulerian PPM code we investigate the formation and the properties of the accretion torus around the stellar mass black hole which we assume to originate from the remnant of a neutron star merger within the dynamical time scale of a few milliseconds. The simulations are performed with four nested cartesian grids which allow for both a good resolution near the central black hole and a large computational volume. They include the use of a physical equation of state as well as the neutrino emission from the hot matter of the torus. The gravity of the black hole is described with a Newtonian and alternatively with a Paczyński-Wiita potential. In a post-processing step, we evaluate our models for the energy deposition by nu bar nu annihilation around the accretion torus. We find that the torus formed after neutron star merging has a mass between several 10(-2} M_{sun) and a few 10(-1} M_{sun) with maximum densities around 10(12) g cm(-3) and maximum temperatures of about 10 MeV (entropies around 5 k_B per nucleon). Correspondingly, the neutrino emission is huge with a total luminosity near 10(53) erg s(-1) . Neutrino-antineutrino annihilation deposits energy in the vicinity of the torus at a rate of (3-5)x 10(50) erg s(-1) . It is most efficient near the rotation axis where 10 to 30% of this energy or up to a total of 10(49) erg are dumped within an estimated emission period of 0.02-0.1 s in a region with a low integral baryonic mass of about 10(-5} M_{sun) . This baryon pollution is still dangerously high, and the estimated maximum relativistic Lorentz factors Gamma -1 are around unity. The conversion of neutrino energy into a pair plasma, however, is sufficiently powerful to blow out the baryons along the axis so that a clean funnel should be produced within only milliseconds. Our models show that accretion on the black hole formed after neutron star merging can yield enough energy by nu bar nu annihilation to account for weak, short gamma-ray bursts, if moderate beaming is involved. In fact, the barrier of the dense baryonic gas of the torus suggests that the low-density e(+/-gamma ) plasma is beamed as axial jets into a fraction f_Ω = 2delta Omega /(4pi ) between 1/100 and 1/10 of the sky, corresponding to opening half-angles of roughly ten to several tens of degrees. Thus gamma -burst energies of E_γ~ E_{nu bar nu }/f_Ω<~ 10(50) -10(51) erg seem to be within the reach of accreting black holes formed in neutron star mergers (if the source is interpreted as radiating isotropically), corresponding to luminosities around 10(51) erg s(-1) for typical burst durations of 0.1-1 s. Gravitational capture of radiation by the black hole, redshift and ray bending do not reduce the jet energy significantly, because most of the neutrino emission comes from parts of the torus at distances of several Schwarzschild radii from the black hole. Effects associated with the Kerr character of the rapidly rotating black hole, however, could increase the gamma -burst energy considerably, and effects due to magnetic fields might even be required to get the energies for long complex gamma-ray bursts.

Blazar Sheath Illumination of the Outer Molecular Torus: A Resolution of the Seed Photon Problem for the Far-GeV Blazar Flares

NASA Astrophysics Data System (ADS)

Breiding, Peter; Georganopoulos, Markos; Meyer, Eileen T.

2018-01-01

Recent multiwavelength work led by the Boston University blazar group (e.g., Marscher et al.) strongly suggests that a fraction of the blazar flares seen by the Fermi Large Area Telescope (LAT) take place a few to several pc away from the central engine. However, at such distances from the central engine, there is no adequate external photon field to provide the seed photons required for producing the observed GeV emission under leptonic inverse Compton (IC) models. A possible solution is a spine-sheath geometry for the emitting region (MacDonald et al., but see Nalewajko et al.). Here we use the current view of the molecular torus (e.g., Elitzur; Netzer), in which the torus extends a few pc beyond the dust sublimation radius with dust clouds distributed with a declining density for decreasing polar angle. We show that for a spine-sheath blazar jet embedded in the torus, the wide beaming pattern of the synchrotron radiation of the relatively slow sheath will heat molecular clouds with subsequent IR radiation that will be highly boosted in the spine comoving frame, and that under reasonable conditions this photon field can dominate over the sheath photons directly entering the spine. If the sheath is sufficiently luminous it will sublimate the dust, and if the sheath synchrotron radiation extends to optical-UV energies (as may happen during flares), this will illuminate the sublimated dust clouds to produce emission lines that will vary in unison with the optical-UV continuum, as has been very recently reported for blazar CTA 102 (Jorstad et al.).

The Nature of the Torus in the Heavily Obscured AGN Markarian 3: an X-Ray Study

NASA Technical Reports Server (NTRS)

Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S.E; Brandt, W. N.; Brightman, M.; Christensen, F. E.;

THE OBSCURED FRACTION OF ACTIVE GALACTIC NUCLEI IN THE XMM-COSMOS SURVEY: A SPECTRAL ENERGY DISTRIBUTION PERSPECTIVE

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

Lusso, E.; Hennawi, J. F.; Richards, G. T.

2013-11-10

The fraction of active galactic nucleus (AGN) luminosity obscured by dust and re-emitted in the mid-IR is critical for understanding AGN evolution, unification, and parsec-scale AGN physics. For unobscured (Type 1) AGNs, where we have a direct view of the accretion disk, the dust covering factor can be measured by computing the ratio of re-processed mid-IR emission to intrinsic nuclear bolometric luminosity. We use this technique to estimate the obscured AGN fraction as a function of luminosity and redshift for 513 Type 1 AGNs from the XMM-COSMOS survey. The re-processed and intrinsic luminosities are computed by fitting the 18 bandmore » COSMOS photometry with a custom spectral energy distribution fitting code, which jointly models emission from hot dust in the AGN torus, from the accretion disk, and from the host galaxy. We find a relatively shallow decrease of the luminosity ratio as a function of L{sub bol}, which we interpret as a corresponding decrease in the obscured fraction. In the context of the receding torus model, where dust sublimation reduces the covering factor of more luminous AGNs, our measurements require a torus height that increases with luminosity as h ∝ L{sub bol}{sup 0.3-0.4}. Our obscured-fraction-luminosity relation agrees with determinations from Sloan Digital Sky Survey censuses of Type 1 and Type 2 quasars and favors a torus optically thin to mid-IR radiation. We find a much weaker dependence of the obscured fraction on 2-10 keV luminosity than previous determinations from X-ray surveys and argue that X-ray surveys miss a significant population of highly obscured Compton-thick AGNs. Our analysis shows no clear evidence for evolution of the obscured fraction with redshift.« less

Investigation of irradiation effects on highly integrated leading-edge electronic components of diagnostics and control systems for LHD deuterium operation

NASA Astrophysics Data System (ADS)

Ogawa, K.; Nishitani, T.; Isobe, M.; Murata, I.; Hatano, Y.; Matsuyama, S.; Nakanishi, H.; Mukai, K.; Sato, M.; Yokota, M.; Kobuchi, T.; Nishimura, T.; Osakabe, M.

2017-08-01

High-temperature and high-density plasmas are achieved by means of real-time control, fast diagnostic, and high-power heating systems. Those systems are precisely controlled via highly integrated electronic components, but can be seriously affected by radiation damage. Therefore, the effects of irradiation on currently used electronic components should be investigated for the control and measurement of Large Helical Device (LHD) deuterium plasmas. For the precise estimation of the radiation field in the LHD torus hall, the MCNP6 code is used with the cross-section library ENDF B-VI. The geometry is modeled on the computer-aided design. The dose on silicon, which is a major ingredient of electronic components, over nine years of LHD deuterium operation shows that the gamma-ray contribution is dominant. Neutron irradiation tests were performed in the OKTAVIAN at Osaka University and the Fast Neutron Laboratory at Tohoku University. Gamma-ray irradiation tests were performed at the Nagoya University Cobalt-60 irradiation facility. We found that there are ethernet connection failures of programmable logic controller (PLC) modules due to neutron irradiation with a neutron flux of 3  ×  106 cm-2 s-1. This neutron flux is equivalent to that expected at basement level in the LHD torus hall without a neutron shield. Most modules of the PLC are broken around a gamma-ray dose of 100 Gy. This is comparable with the dose in the LHD torus hall over nine years. If we consider the dose only, these components may survive more than nine years. For the safety of the LHD operation, the electronic components in the torus hall have been rearranged.

Large inflated-antenna system

NASA Technical Reports Server (NTRS)

Hinson, W. F.; Keafer, L. S.

1984-01-01

It is proposed that for inflatable antenna systems, technology feasibility can be demonstrated and parametric design and scalability (scale factor 10 to 20) can be validated with an experiment using a 16-m-diameter antenna attached to the Shuttle. The antenna configuration consists of a thin film cone and paraboloid held to proper shape by internal pressure and a self-rigidizing torus. The cone and paraboloid would be made using pie-shaped gores with the paraboloid being coated with aluminum to provide reflectivity. The torus would be constructed using an aluminum polyester composite that when inflated would erect to a smooth shell that can withstand loads without internal pressure.

A Direct Approach to the Villarceau Circles of a Torus.

DTIC Science & Technology

1984-03-01

8217 following theorem . , Theorem 1. On F and F’ we select points P and P’, respectively, such that (4) 8 "LAOP, * =LAO’P’, (0 ( 8, * < 2), bi X,$ x ~-2- i4...6) by replacing c by -c. Proof of Theorem 1. In the cartesian, axes O’xyz of Fig. I we have .1, 1)P: x c + aoo 0, y- a sin0, z 0 -3- We now rotate...Bottema, Cirkels op een torus, Pythagoras , 19 (1979) 2 7. 2. Z. A. Nelzak, Invitation to Geometry, John Wiley & Sons, New York, 1983. 3. Y. Villarceau

Hawking Tunneling Radiation of Black Holes in de Sitter and ANTI-de Sitter Spacetimes

NASA Astrophysics Data System (ADS)

Jiang, Qing-Quan; Li, Hui-Ling; Yang, Shu-Zheng; Chen, De-You

Applying Parikh-Wilczek's semiclassical quantum tunneling method, we investigate the tunneling radiation characteristics of a torus-like black hole and Kerr-Newman-Kausya de Sitter black hole. Both black holes have the cosmological constant Λ, but a torus-like black hole is in anti-de Sitter spacetime and the other black hole is in de Sitter spacetime. The derived results show that the tunneling rate is related to the change of Bekenstein-Hawking entropy, and the factual radiated spectrum is not precisely thermal, but is consistent with an underlying unitary theory, which gives a might explanation to the paradox of black hole information lost.

Torus-margo pits help conifers compete with angiosperms.

PubMed

Pittermann, Jarmila; Sperry, John S; Hacke, Uwe G; Wheeler, James K; Sikkema, Elzard H

2005-12-23

The unicellular conifer tracheid should have greater flow resistance per length (resistivity) than the multicellular angiosperm vessel, because its high-resistance end-walls are closer together. However, tracheids and vessels had comparable resistivities for the same diameter, despite tracheids being over 10 times shorter. End-wall pits of tracheids averaged 59 times lower flow resistance on an area basis than vessel pits, owing to the unique torus-margo structure of the conifer pit membrane. The evolution of this membrane was as hydraulically important as that of vessels. Without their specialized pits, conifers would have 38 times the flow resistance, making conifer-dominated ecosystems improbable in an angiosperm world.

HOMFLYPT polynomial is the best quantifier for topological cascades of vortex knots

NASA Astrophysics Data System (ADS)

Ricca, Renzo L.; Liu, Xin

2018-02-01

In this paper we derive and compare numerical sequences obtained by adapted polynomials such as HOMFLYPT, Jones and Alexander-Conway for the topological cascade of vortex torus knots and links that progressively untie by a single reconnection event at a time. Two cases are considered: the alternate sequence of knots and co-oriented links (with positive crossings) and the sequence of two-component links with oppositely oriented components (negative crossings). New recurrence equations are derived and sequences of numerical values are computed. In all cases the adapted HOMFLYPT polynomial proves to be the best quantifier for the topological cascade of torus knots and links.

Electronic Circuit Experiments and SPICE Simulation of Double Covering Bifurcation of 2-Torus Quasi-Periodic Flow in Phase-Locked Loop Circuit

NASA Astrophysics Data System (ADS)

Kamiyama, Kyohei; Endo, Tetsuro; Imai, Isao; Komuro, Motomasa

2016-06-01

Double covering (DC) bifurcation of a 2-torus quasi-periodic flow in a phase-locked loop circuit was experimentally investigated using an electronic circuit and via SPICE simulation; in the circuit, the input radio-frequency signal was frequency modulated by the sum of two asynchronous sinusoidal baseband signals. We observed both DC and period-doubling bifurcations of a discrete map on two Poincaré sections, which were realized by changing the sample timing from one baseband sinusoidal signal to the other. The results confirm the DC bifurcation of the original flow.

Development of internal magnetic probe for current density profile measurement in Versatile Experiment Spherical Torus

NASA Astrophysics Data System (ADS)

Yang, J.; Lee, J. W.; Jung, B. K.; Chung, K. J.; Hwang, Y. S.

2014-11-01

An internal magnetic probe using Hall sensors to measure a current density profile directly with perturbation of less than 10% to the plasma current is successfully operated for the first time in Versatile Experiment Spherical Torus (VEST). An appropriate Hall sensor is chosen to produce sufficient signals for VEST magnetic field while maintaining the small size of 10 mm in outer diameter. Temperature around the Hall sensor in a typical VEST plasma is regulated by blown air of 2 bars. First measurement of 60 kA VEST ohmic discharge shows a reasonable agreement with the total plasma current measured by Rogowski coil in VEST.

Momentum-transport studies in high E x B shear plasmas in the National Spherical Torus Experiment.

PubMed

Solomon, W M; Kaye, S M; Bell, R E; Leblanc, B P; Menard, J E; Rewoldt, G; Wang, W; Levinton, F M; Yuh, H; Sabbagh, S A

2008-08-08

Experiments have been conducted at the National Sperical Torus Experiment (NSTX) to study both steady state and perturbative momentum transport. These studies are unique in their parameter space under investigation, where the low aspect ratio of NSTX results in rapid plasma rotation with ExB shearing rates high enough to suppress low-k turbulence. In some cases, the ratio of momentum to energy confinement time is found to exceed five. Momentum pinch velocities of order 10-40 m/s are inferred from the measured angular momentum flux evolution after nonresonant magnetic perturbations are applied to brake the plasma.

Principal component analysis on a torus: Theory and application to protein dynamics.

PubMed

Sittel, Florian; Filk, Thomas; Stock, Gerhard

2017-12-28

A dimensionality reduction method for high-dimensional circular data is developed, which is based on a principal component analysis (PCA) of data points on a torus. Adopting a geometrical view of PCA, various distance measures on a torus are introduced and the associated problem of projecting data onto the principal subspaces is discussed. The main idea is that the (periodicity-induced) projection error can be minimized by transforming the data such that the maximal gap of the sampling is shifted to the periodic boundary. In a second step, the covariance matrix and its eigendecomposition can be computed in a standard manner. Adopting molecular dynamics simulations of two well-established biomolecular systems (Aib 9 and villin headpiece), the potential of the method to analyze the dynamics of backbone dihedral angles is demonstrated. The new approach allows for a robust and well-defined construction of metastable states and provides low-dimensional reaction coordinates that accurately describe the free energy landscape. Moreover, it offers a direct interpretation of covariances and principal components in terms of the angular variables. Apart from its application to PCA, the method of maximal gap shifting is general and can be applied to any other dimensionality reduction method for circular data.

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

Furui, Shun’ya; Fukazawa, Yasushi; Ohno, Masanori

We construct an X-ray spectral model of reprocessing by a torus in an active galactic nucleus (AGN) with the Monte Carlo simulation framework MONACO. Two torus geometries of smooth and clumpy cases are considered and compared. In order to reproduce a Compton shoulder accurately, MONACO includes not only free electron scattering but also bound electron scattering. Raman and Rayleigh scattering are also treated, and scattering cross sections dependent on chemical states of hydrogen and helium are included. Doppler broadening by turbulence velocity can be implemented. Our model gives results consistent with other available models, such as MYTorus, except for differencesmore » due to different physical parameters and assumptions. We studied the dependence on torus parameters for a Compton shoulder, and found that a intensity ratio of a Compton shoulder to the line core mainly depends on column density, inclination angle, and metal abundance. For instance, an increase of metal abundance makes a Compton shoulder relatively weak. Also, the shape of a Compton shoulder depends on the column density. Furthermore, these dependences become different between smooth and clumpy cases. Then, we discuss the possibility of ASTRO-H/SXS spectroscopy of Compton shoulders in AGN reflection spectra.« less

Calibration of neutron detectors on the Joint European Torus.

PubMed

Batistoni, Paola; Popovichev, S; Conroy, S; Lengar, I; Čufar, A; Abhangi, M; Snoj, L; Horton, L

2017-10-01

The present paper describes the findings of the calibration of the neutron yield monitors on the Joint European Torus (JET) performed in 2013 using a 252 Cf source deployed inside the torus by the remote handling system, with particular regard to the calibration of fission chambers which provide the time resolved neutron yield from JET plasmas. The experimental data obtained in toroidal, radial, and vertical scans are presented. These data are first analysed following an analytical approach adopted in the previous neutron calibrations at JET. In this way, a calibration function for the volumetric plasma source is derived which allows us to understand the importance of the different plasma regions and of different spatial profiles of neutron emissivity on fission chamber response. Neutronics analyses have also been performed to calculate the correction factors needed to derive the plasma calibration factors taking into account the different energy spectrum and angular emission distribution of the calibrating (point) 252 Cf source, the discrete positions compared to the plasma volumetric source, and the calibration circumstances. All correction factors are presented and discussed. We discuss also the lessons learnt which are the basis for the on-going 14 MeV neutron calibration at JET and for ITER.

Principal component analysis on a torus: Theory and application to protein dynamics

NASA Astrophysics Data System (ADS)

Sittel, Florian; Filk, Thomas; Stock, Gerhard

2017-12-01

A dimensionality reduction method for high-dimensional circular data is developed, which is based on a principal component analysis (PCA) of data points on a torus. Adopting a geometrical view of PCA, various distance measures on a torus are introduced and the associated problem of projecting data onto the principal subspaces is discussed. The main idea is that the (periodicity-induced) projection error can be minimized by transforming the data such that the maximal gap of the sampling is shifted to the periodic boundary. In a second step, the covariance matrix and its eigendecomposition can be computed in a standard manner. Adopting molecular dynamics simulations of two well-established biomolecular systems (Aib9 and villin headpiece), the potential of the method to analyze the dynamics of backbone dihedral angles is demonstrated. The new approach allows for a robust and well-defined construction of metastable states and provides low-dimensional reaction coordinates that accurately describe the free energy landscape. Moreover, it offers a direct interpretation of covariances and principal components in terms of the angular variables. Apart from its application to PCA, the method of maximal gap shifting is general and can be applied to any other dimensionality reduction method for circular data.

Compact Torus Fueling of the STOR-M Tokamak

NASA Astrophysics Data System (ADS)

Xiao, C.; Hirose, A.; Zawalski, W.; White, D.; Raman, R.; Decoste, R.; Gregory, B. C.; Martin, F.

1996-11-01

Tangential injection of accelerated compact torus (CT) has been performed on the STOR-M tokamak (R/a=46/12 cm, B_t<1 T, I_p<= 50 kA, barn_e=(0.5 - 1)×10^13 cm-3) using the University of Saskatchewan Compact Torus Injector (USCTI). The CT parameters are: m~=1 μg, v=120 km/sec, B=0.1 T and n=(2 - 4)×10^15 cm-3. After CT injection, the electron density in tokamak doubles and the poloidal β-value increases. Indications of reduction in the loop voltage and H_α emission level have also been observed. Currently, following efforts are being made: (a) to coat chromium on the electrode surface, (b) to increase the on-line baking temperature, and (c) to reduce the neutral gas load which follows the CT plasma. In addition, numerical calculation of CT motion in a tokamak magnetic field has been carried out. For horizontal injection, the initial CT magnetic dipole direction should be aligned with the CT velocity for deeper penetration. In the case of vertical injection, the CT trajectory is independent of the initial magnetic dipole direction and central penetration is facilitated by off-axis injection.

Escape mechanisms of dust in Io

NASA Astrophysics Data System (ADS)

Flandes, A.

The injection of material into the jovian magnetosphere through Io's volcanic activity makes possible the formation of structures such as the plasma torus and the dust ballerina skirt. Io's high temperature volcanism produces spectacular plumes, but even the tallest plumes, as those of Pelen Patera, will not produce enough energy to defeat the gravitational attraction of Io. The fact is that dust escapes from Io, which implies that a second mechanism is acting on the grains. Grains brought to the top of the highest plumes by the volcanic forces are still under Io's gravitational pull, but need only a minimum charge (~10-1 4 C) so that the Lorentz force due to the Jovian magnetic field equilibrates this attraction. In the volcanic vents, the escape velocity of the ejected material and its own density produces enough collisions to create charges. On top of the highest plumes (~500km) charged grains are exposed to the plasma torus that co-rotates rigidly with Jupiter and, due to the relative velocity among Io and the torus, the grains will be dragged away from Io. As it is well known, these dust grains will also be dragged away from Jupiter.

The Physics Performance Of The Front Steering Launcher For The ITER ECRH Upper Port

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

Henderson, M.; Chavan, R.; Nikkola, P.

2005-09-26

The capability of any given e.m.-wave plasma heating system to be utilized for physics applications depends strongly on the technical properties of the launching antenna (or launcher). An effective ECH launcher must project a small mm-wave beam spot size far into the plasma and 'steer' the beam across a large fraction of the plasma cross section (along the resonance surface). Thus the choice in the launcher concept and design may either severely limit or enhance the capability of a heating system to be effectively applied for physics applications, such as sawtooth stabilization, control of the Neoclassical Tearing Mode (NTM), Edgemore » Localized Mode (ELM) control, etc. Presently, two antenna concepts are under consideration for the ITER upper port ECH launcher: front steering (FS) and remote steering (RS) launchers. The RS launcher has the technical advantage of easier maintenance access to the steering mirror, which is isolated from the torus vacuum. The FS launcher places the steering mirror near the plasma increasing the technical challenges, but significantly enhancing the focusing and steering capabilities of the launcher, offering a threefold increase in NTM stabilization efficiency over the RS launcher as well as the potential for application to other critical physics issues such as ELM or sawtooth control.« less

Study of shuttle imaging microwave system antenna. Volume 1: Conceptual design

NASA Technical Reports Server (NTRS)

Wesley, R. W.; Waineo, D. K.; Barton, C. R.; Love, A. W.

1975-01-01

A detailed preliminary design and complete performance evaluation are presented of an 11-channel large aperture scanning radiometer antenna for the shuttle imaging microwave system (SIMS) program. Provisions for interfacing the antenna with the space shuttle orbiter are presented and discussed. A program plan for hardware development and a rough order of magnitude (ROM) cost are also included. The conceptual design of the antenna is presented. It consists of a four-meter diameter parabolic torus main reflector, which is a graphite/epoxy shell supported by a graphite/epoxy truss. A rotating feed wheel assembly supports six Gregorian subreflectors covering the upper eight frequency channels from 6.6 GHz through 118.7 GHz, and two three-channel prime forms feed assemblies for 0.6, 1.4, and 2.7 GHz. The feed wheel assembly also holds the radiometers and power supplies, and a drive system using a 400 Hz synchronous motor is described. The RF analysis of the antenna is performed using physical optics procedures for both the dual reflector Gregorian concept and the single reflector prime focus concept. A unique aberration correcting feed for 2.7 GHz is analyzed. A structural analysis is also included. The analyses indicate that the antenna will meet system requirements.

Icy Erosion

NASA Image and Video Library

2015-12-23

This image from NASA Mars Reconnaissance Orbiter spacecraft shows an interesting collection of kilometer-scale craters with flat and smooth floors. The craters themselves may be the result of secondary impacts, craters caused by debris from a distant larger impact. Since then, the surface has been significantly modified and reworked, muting the craters and flattening their floors. Presently, there are a few sand dunes and a broad overlay of a dusty soil mantle. This soil mantle occurs over much of the middle latitudes of Mars. Here, as elsewhere, the mantle covers these craters, but a closer inspection reveals that its smooth texture becomes significantly pitted and bumpy on the pole facing slopes of each crater interior wall. http://photojournal.jpl.nasa.gov/catalog/PIA20288

Advanced use of tissue adhesive in hair transplantation.

PubMed

Elliott, R M; Thomas, R A; True, R H

1993-09-01

Cobblestoning is an unsightly result of graft elevation in the recipient site after hair transplantation. To describe the use of tissue adhesives for the avoidance of cobblestoning. The long-term cosmetic appearance of hair transplants may be improved through the use of cyanoacrylate adhesives is the virtual elimination of the common problem of graft elevation or cobblestoning, which produces an unsightly bumpiness in the recipient area. The choice of type of adhesive and the method of application are central to successful use of this technique. The indirect benefits of elimination of the need for postoperative bandages and restrictions in activities couple with the cosmetic results to produce a high degree of patient satisfaction.

Simulations of coronagraphy with a dynamic hologram for the direct detection of exo-planets

NASA Astrophysics Data System (ADS)

Ricci, Davide; Le Coroller, Hervé; Labeyrie, Antoine; Piron, Pierre

2010-07-01

In a previous paper,1 we discussed an original solution to improve the performances of coronagraphs by adding, in the optical scheme, an adaptive hologram removing most of the residual speckle starlight. In our simulations, the detection limit in the flux ratio between a host star and a very near planet (5λ/D) improves over a factor 1000 (resp. 10000) when equipped with a hologram for cases of wavefront bumpiness imperfections of λ/20 (resp. λ/100). We derive, in this paper, the transmission accuracy required on the hologram pixels to achieve such goals. We show that preliminary tests could be performed on the basis of existing technologies.

A Study of the Initiation Process of Coronal Mass Ejections and the Tool for Their Auto-Detection

NASA Astrophysics Data System (ADS)

Olmedo, Oscar

Coronal mass ejections (CMEs) are the most energetic and important solar activity. They are often associated with other solar phenomena such as flares and filament/prominence eruptions. Despite the significant improvement of CME study in the past decade, our understanding of the initiation process of CMEs remains elusive. In order to solve this issue, an approach that combines theoretical modelling and empirical analysis is needed. This thesis is a combination of three studies, two of which investigate the initiation process of CMEs, and the other is the development of a tool to automatically detect CMEs. First, I investigate the stability of the well-known eruptive flux rope model in the context of the torus instability. In the flux rope model, the pre-eruptive CME structure is a helical flux rope with two footpoints anchored to the solar surface. The torus instability is dependent on the balance between two opposing magnetic forces, the outward Lorentz self-force (also called curvature hoop force) and the restoring Lorentz force of the ambient magnetic fields. Previously, the condition of stability derived for the torus instability assumed that the pre-eruptive structure was a semicircular loop above the photosphere without anchored footpoints. I extend these results to partial torus flux ropes of any circularity with anchored footpoints and discovered that there is a dependence of the critical index on the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. I coin this result the partial torus instability (PTI). The result is more general than has been previously derived and extends to loops of any arc above the photosphere. It will be demonstrated that these results can help us understand the confinement, growth, and eventual eruption of a flux rope CME. Second, I use observations of eruptive prominences associated with CMEs to examine the behaviour of their initiation and compare these observations to theoretical models. Since theoretical models specify the pre-existence of a flux rope, the observational challenge is the interpretation of the flux rope in solar images. A good proxy for flux ropes is prominences, because of its obvious elongated helical structure above the magnetic polarity line. I compare the prominence kinematics and the associated extrapolated magnetic fields. This observational study yields two key conclusions. The first is that there is a dependence of the ejecta's kinematics on how the ambient magnetic field decay's. The second is that the critical decay index, theorized to be where the flux rope transitions from a stable to unstable configuration, is dependent on the geometry of the loop. This second result is in qualitative agreement with the theorized PTI. Finally, I develop a tool to automatically detect CME events in coronagraph images. Because of the large amount of data collected over the years, searching for candidate events to study can be daunting. In order to facilitate the search of CME event candidates, an algorithm was developed to automatically detect and characterize CMEs seen in coronagraph images. With this tool, one need not scroll through the large number of images, and only focus on particular subsets. The auto-detection reduces human bias of CME characterization. Such automated detection algorithms can have other applications, such as space weather alerts in near-real time. In summary, this thesis has improved our understanding of the initiation process of CMEs by taking both theoretical and observational studies. Future work includes investigating a larger number of events to give a better statistical characterization of the results found in the observational study. Furthermore, modification to the theoretical model of the PTI, for example by ncluding a repulsive force due to induced photospheric currents, can improve the quantitative agreement with observations. The complete knowledge of the initiation of CMEs is important because it can help us to predict when such an event may occur. Such a prediction can aid in mitigating severe space weather effects at the Earth.

Static and Dynamic Model Update of an Inflatable/Rigidizable Torus Structure

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Reaves, mercedes C.

2006-01-01

The present work addresses the development of an experimental and computational procedure for validating finite element models. A torus structure, part of an inflatable/rigidizable Hexapod, is used to demonstrate the approach. Because of fabrication, materials, and geometric uncertainties, a statistical approach combined with optimization is used to modify key model parameters. Static test results are used to update stiffness parameters and dynamic test results are used to update the mass distribution. Updated parameters are computed using gradient and non-gradient based optimization algorithms. Results show significant improvements in model predictions after parameters are updated. Lessons learned in the areas of test procedures, modeling approaches, and uncertainties quantification are presented.

Vacuum system design and tritium inventory for the TFTR charge exchange diagnostic

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

Medley, S.S.

The charge exchange diagnostic for the TFTR is comprised of two analyzer systems which contain a total of twenty independent mass/energy analyzers and one diagnostic neutral beam tentatively rated at 80 keV, 15 A. The associated vacuum systems were analyzed using the Vacuum System Transient Simulator (VSTS) computer program which models the transient transport of multi-gas species through complex networks of ducts, valves, traps, vacuum pumps, and other related vacuum system components. In addition to providing improved design performance at reduced cost, the analysis yields estimates for the exchange of tritium from the torus to the diagnostic components and ofmore » the diagnostic working gases to the torus.« less

Voyager 1 Planetary Radio Astronomy Observations Near Jupiter

NASA Technical Reports Server (NTRS)

Warwick, J. W.; Pearce, J. B.; Riddle, A. C.; Alexander, J. K.; Desch, M. D.; Kaiser, M. L.; Thieman, J. R.; Carr, T. B.; Gulkis, S.; Boischot, A.

1979-01-01

Results are reported from the first low frequency radio receiver to be transported into the Jupiter magnetosphere. Dramatic new information was obtained both because Voyager was near or in Jupiter's radio emission sources and also because it was outside the relatively dense solar wind plasma of the inner solar system. Extensive radio arcs, from above 30 MHz to about 1 MHz, occurred in patterns correlated with planetary longitude. A newly discovered kilometric wavelength radio source may relate to the plasma torus near Io's orbit. In situ wave resonances near closest approach define an electron density profile along the Voyager trajectory and form the basis for a map of the torus. Studies in progress are outlined briefly.

Entanglement, space-time and the Mayer-Vietoris theorem

NASA Astrophysics Data System (ADS)

Patrascu, Andrei T.

2017-06-01

Entanglement appears to be a fundamental building block of quantum gravity leading to new principles underlying the nature of quantum space-time. One such principle is the ER-EPR duality. While supported by our present intuition, a proof is far from obvious. In this article I present a first step towards such a proof, originating in what is known to algebraic topologists as the Mayer-Vietoris theorem. The main result of this work is the re-interpretation of the various morphisms arising when the Mayer-Vietoris theorem is used to assemble a torus-like topology from more basic subspaces on the torus in terms of quantum information theory resulting in a quantum entangler gate (Hadamard and c-NOT).

Periodic arrays of M2-branes

NASA Astrophysics Data System (ADS)

Jeon, Imtak; Lambert, Neil; Richmond, Paul

2012-11-01

We consider periodic arrays of M2-branes in the ABJM model in the spirit of a circle compactification to D2-branes in type IIA string theory. The result is a curious formulation of three-dimensional maximally supersymmetric Yang-Mills theory in terms of fermions, seven transverse scalars, a non-dynamical gauge field and an additional scalar `dual gluon'. Upon further T-duality on a transverse torus we obtain a non-manifest- Lorentz-invariant description of five-dimensional maximally supersymmetric Yang-Mills. Here the additional scalar field can be thought of as the components of a two-form along the torus. This action can be viewed as an M-theory description of M5-branes on {{{T}}^3}.

ON THE RADIO DETECTION OF MULTIPLE-EXOMOON SYSTEMS DUE TO PLASMA TORUS SHARING

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

Noyola, J. P.; Satyal, S.; Musielak, Z. E., E-mail: jpnoyola@uta.edu, E-mail: ssatyal@uta.edu, E-mail: zmusielak@uta.edu

2016-04-20

The idea of single exomoon detection due to the radio emissions caused by its interaction with the host exoplanet is extended to multiple-exomoon systems. The characteristic radio emissions are made possible in part by plasma from the exomoon’s own ionosphere. In this work, it is demonstrated that neighboring exomoons and the exoplanetary magnetosphere could also provide enough plasma to generate a detectable signal. In particular, the plasma-torus-sharing phenomenon is found to be particularly well suited to facilitate the radio detection of plasma-deficient exomoons. The efficiency of this process is evaluated, and the predicted power and frequency of the resulting radiomore » signals are presented.« less

Vector-valued Jack polynomials and wavefunctions on the torus

NASA Astrophysics Data System (ADS)

Dunkl, Charles F.

2017-06-01

The Hamiltonian of the quantum Calogero-Sutherland model of N identical particles on the circle with 1/r 2 interactions has eigenfunctions consisting of Jack polynomials times the base state. By use of the generalized Jack polynomials taking values in modules of the symmetric group and the matrix solution of a system of linear differential equations one constructs novel eigenfunctions of the Hamiltonian. Like the usual wavefunctions each eigenfunction determines a symmetric probability density on the N-torus. The construction applies to any irreducible representation of the symmetric group. The methods depend on the theory of generalized Jack polynomials due to Griffeth, and the Yang-Baxter graph approach of Luque and the author.

Observation of instability-induced current redistribution in a spherical-torus plasma.

PubMed

Menard, J E; Bell, R E; Gates, D A; Kaye, S M; LeBlanc, B P; Levinton, F M; Medley, S S; Sabbagh, S A; Stutman, D; Tritz, K; Yuh, H

2006-09-01

A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER.

Two-point motional Stark effect diagnostic for Madison Symmetric Torus

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

Ko, J.; Den Hartog, D. J.; Caspary, K. J.

2010-10-15

A high-precision spectral motional Stark effect (MSE) diagnostic provides internal magnetic field measurements for Madison Symmetric Torus (MST) plasmas. Currently, MST uses two spatial views - on the magnetic axis and on the midminor (off-axis) radius, the latter added recently. A new analysis scheme has been developed to infer both the pitch angle and the magnitude of the magnetic field from MSE spectra. Systematic errors are reduced by using atomic data from atomic data and analysis structure in the fit. Reconstructed current density and safety factor profiles are more strongly and globally constrained with the addition of the off-axis radiusmore » measurement than with the on-axis one only.« less

Helicity of a toroidal vortex with swirl

NASA Astrophysics Data System (ADS)

Bannikova, E. Yu.; Kontorovich, V. M.; Poslavsky, S. A.

2016-04-01

Based on the solutions of the Bragg-Hawthorne equation, we discuss the helicity of a thin toroidal vortex in the presence of swirl, orbital motion along the torus directrix. The relation between the helicity and circulations along the small and large linked circumferences (the torus directrix and generatrix) is shown to depend on the azimuthal velocity distribution in the core of the swirling ring vortex. In the case of nonuniform swirl, this relation differs from the well-known Moffat relation, viz., twice the product of such circulations multiplied by the number of linkages. The results can find applications in investigating the vortices in planetary atmospheres and the motions in the vicinity of active galactic nuclei.

Quantum Entanglement and the Topological Order of Fractional Hall States

NASA Astrophysics Data System (ADS)

Rezayi, Edward

2015-03-01

Fractional quantum Hall states or, more generally, topological phases of matter defy Landau classification based on order parameter and broken symmetry. Instead they have been characterized by their topological order. Quantum information concepts, such as quantum entanglement, appear to provide the most efficient method of detecting topological order solely from the knowledge of the ground state wave function. This talk will focus on real-space bi-partitioning of quantum Hall states and will present both exact diagonalization and quantum Monte Carlo studies of topological entanglement entropy in various geometries. Results on the torus for non-contractible cuts are quite rich and, through the use of minimum entropy states, yield the modular S-matrix and hence uniquely determine the topological order, as shown in recent literature. Concrete examples of minimum entropy states from known quantum Hall wave functions and their corresponding quantum numbers, used in exact diagonalizations, will be given. In collaboration with Clare Abreu and Raul Herrera. Supported by DOE Grant DE-SC0002140.

Steady flow of smooth, inelastic particles on a bumpy inclined plane: Hard and soft particle simulations

NASA Astrophysics Data System (ADS)

Tripathi, Anurag; Khakhar, D. V.

2010-04-01

We study smooth, slightly inelastic particles flowing under gravity on a bumpy inclined plane using event-driven and discrete-element simulations. Shallow layers (ten particle diameters) are used to enable simulation using the event-driven method within reasonable computational times. Steady flows are obtained in a narrow range of angles (13°-14.5°) ; lower angles result in stopping of the flow and higher angles in continuous acceleration. The flow is relatively dense with the solid volume fraction, ν≈0.5 , and significant layering of particles is observed. We derive expressions for the stress, heat flux, and dissipation for the hard and soft particle models from first principles. The computed mean velocity, temperature, stress, dissipation, and heat flux profiles of hard particles are compared to soft particle results for different values of stiffness constant (k) . The value of stiffness constant for which results for hard and soft particles are identical is found to be k≥2×106mg/d , where m is the mass of a particle, g is the acceleration due to gravity, and d is the particle diameter. We compare the simulation results to constitutive relations obtained from the kinetic theory of Jenkins and Richman [J. T. Jenkins and M. W. Richman, Arch. Ration. Mech. Anal. 87, 355 (1985)] for pressure, dissipation, viscosity, and thermal conductivity. We find that all the quantities are very well predicted by kinetic theory for volume fractions ν<0.5 . At higher densities, obtained for thicker layers ( H=15d and H=20d ), the kinetic theory does not give accurate prediction. Deviations of the kinetic theory predictions from simulation results are relatively small for dissipation and heat flux and most significant deviations are observed for shear viscosity and pressure. The results indicate the range of applicability of soft particle simulations and kinetic theory for dense flows.

Open strings and electric fields in compact spaces

NASA Astrophysics Data System (ADS)

Condeescu, Cezar; Dudas, Emilian; Pradisi, Gianfranco

2018-05-01

We analyse open strings with background electric fields in the internal space, T-dual to branes moving with constant velocities in the internal space. We find that the direction of the electric fields inside a two torus, dual to the D-brane velocities, has to be quantised such that the corresponding direction is compact. This implies that D-brane motion in the internal torus is periodic, with a periodicity that can be parametrically large in terms of the internal radii. By S-duality, this is mapped into an internal magnetic field in a three torus, a quantum mechanical analysis of which yields a similar result, i.e. the parallel direction to the magnetic field has to be compact. Furthermore, for the magnetic case, we find the Landau level degeneracy as being given by the greatest common divisor of the flux numbers. We carry on the string quantisation and derive the relevant partition functions for these models. Our analysis includes also the case of oblique electric fields which can arise when several stacks of branes are present. Compact dimensions and/or oblique sectors influence the energy loss of the system through pair-creation and thus can be relevant for inflationary scenarios with branes. Finally, we show that the compact energy loss is always larger than the non-compact one.

The theory of pseudo-differential operators on the noncommutative n-torus

NASA Astrophysics Data System (ADS)

Tao, J.

2018-02-01

The methods of spectral geometry are useful for investigating the metric aspects of noncommutative geometry and in these contexts require extensive use of pseudo-differential operators. In a foundational paper, Connes showed that, by direct analogy with the theory of pseudo-differential operators on finite-dimensional real vector spaces, one may derive a similar pseudo-differential calculus on noncommutative n-tori, and with the development of this calculus came many results concerning the local differential geometry of noncommutative tori for n=2,4, as shown in the groundbreaking paper in which the Gauss-Bonnet theorem on the noncommutative two-torus is proved and later papers. Certain details of the proofs in the original derivation of the calculus were omitted, such as the evaluation of oscillatory integrals, so we make it the objective of this paper to fill in all the details. After reproving in more detail the formula for the symbol of the adjoint of a pseudo-differential operator and the formula for the symbol of a product of two pseudo-differential operators, we extend these results to finitely generated projective right modules over the noncommutative n-torus. Then we define the corresponding analog of Sobolev spaces and prove equivalents of the Sobolev and Rellich lemmas.

Corotation lag limit on mass-loss rate from Io

NASA Astrophysics Data System (ADS)

Huang, T. S.; Siscoe, G. L.

1987-08-01

Considering rapid escape of H2O from Io during an early hot evolutionary epoch, an H2O plasma torus is constructed by balancing dissociation and ionization products against centrifugally driven diffusion, including for the first time the effects of corotation lag resulting from mass loading. Two fundamental limits are found as the mass injection rate increases: (1) an 'ignition' limit of 1.1 x 10 to the 6th kg/s, beyond which the torus cannot ionize itself and photoionization dominates; and (2) the ultimate mass loading limit of 1.3 x 10 to the 7th kg/s, which occurs when neutrals newly created by charge exchange and recombination cannot leave the torus, thereby bringing magnetospherically driven transport to a halt. Connecting this limit with the variations of Io's temperature in its early evolution epoch gives an estimate of the upper limit on the total mass loss from Io, about 3.0 x 10 to the 20th kg (for high-opacity nebula) and about 8.9 x 10 to the 20th kg (for low-opacity nebula). These limits correspond to eroding 8 km and 22 km of H2O from the surface. It is concluded that compared to the other Galilean satellites, Io was created basically dry.

Plasmon dispersion in a multilayer solid torus in terms of three-term vector recurrence relations and matrix continued fractions

DOE PAGES

Garapati, K. V.; Bagherian, M.; Passian, A.; ...

2018-01-03

Toroidal confinement, which has played a crucial role in magnetized plasmas and Tokamak physics, is emerging as an effective means to obtain useful electronic and optical response in solids. In particular, excitation of surface plasmons in metal nanorings by photons or electrons finds important applications due to the engendered field distribution and electromagnetic energy confinement. However, in contrast to the case of a plasma, often the solid nanorings are multilayered and/or embedded in a medium. The non-simply connected geometry of the torus results in surface modes that are not linearly independent. A three-term difference equation was recently shown to arisemore » when seeking the nonretarded plasmon dispersion relations for a stratified solid torus (Garapati et al 2017 Phys. Rev. B 95 165422). The reported generalized plasmon dispersion relations are here investigated in terms of the involved matrix continued fractions and their convergence properties including the determinant forms of the dispersion relations obtained for computing the plasmon eigenmodes. We also present the intricacies of the derivation and properties of the Green's function employed to solve the three term amplitude equation that determines the response of the toroidal structure to arbitrary external excitations.« less

The analysis of ball's motion in the torus-shaped autoequalizer

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

Strautmanis, Guntis, E-mail: Guntis@df.rtu.lv; Jurjev, Vadims, E-mail: vadimsjurjevs@gmail.com; Grinevich, Ivans, E-mail: ivansgrinevics@inbox.lv

2013-12-16

The reduction of vibrations in rotary systems is necessary condition for the development of constructions with high quality requirements. Among the devices that are able to reduce rotor's vibrations are automatic balancers with balls, liquid, etc. Autoequalizers with torus-shaped body contain one ball-shaped adjustment mass that can freely roll both in the ring direction and in the cross section. This enables reducing to the minimum the force of resistance at the ball's moving, but simultaneously decreases the chance of launching the autoequalizer in the autobalancing regime. It has been stated that the ball in the working state is influenced bymore » forces that are aimed at moving it in the body of the autoequalizer towards the side opposite to the imbalance. The design of an autoequalizer that ensures working state in which at rotation the ball stops relative to the autoequalizer's body opposite to the imbalance has been experimentally worked out. The autoequalizer is made up of the mathematical model with two differential equations. In the result of the calculations it has been proved that the ball of an equalizer with the torus-shaped body has at least two movement conditions one of which is a working state, and another one is a spare state.« less

Divertor heat flux mitigation in the National Spherical Torus Experimenta)

NASA Astrophysics Data System (ADS)

Soukhanovskii, V. A.; Maingi, R.; Gates, D. A.; Menard, J. E.; Paul, S. F.; Raman, R.; Roquemore, A. L.; Bell, M. G.; Bell, R. E.; Boedo, J. A.; Bush, C. E.; Kaita, R.; Kugel, H. W.; Leblanc, B. P.; Mueller, D.; NSTX Team

2009-02-01

Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6MWm-2to0.5-2MWm-2 in small-ELM 0.8-1.0MA, 4-6MW neutral beam injection-heated H-mode discharges. A self-consistent picture of the outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.

Experimental Results of OH Regime Investigation in Globus-M Spherical Torus

NASA Astrophysics Data System (ADS)

Golant, Victor; Gusev, Vasily; Levin, Roman; Petrov, Yuriy; Sakharov, Nikolay

2001-10-01

Plasma parameters were measured in novel spherical torus Globus-M in highly shaped plasmas with aspect ratio, A > 1.5, elongation, k < 1.9, triangularity < 0.5. Plasma column was created by direct induction method with the currents up to Ip 0.3 MA in the magnetic field, Bt - 0.08 - 0.5 T. In Globus-M spherical torus plasma column is closely fitted into the vacuum vessel and wall conditioning technology described in [1] was used to achieve good plasma performance. Plasma experiments were focused around achievement of ultimate OH regimes allowed by power supplies. The operational limits of the device were investigated. In the regime with extreme low q(cy1) < 1 and high normalized current > 4, the plasma current of almost 100kA was sustained transiently in low magnetic field 800 Gs. The first results on stability analysis with numerical code are presented. The runaway electrons behavior was studied in spherical tokamak conditions. Influence of plasma current and density ramp-up speeds, MHD events on plasma performance and stability was demonstrated. Magnetic reconstruction was performed with EFIT version adopted for PC simulations. Plans for auxiliary heating and current drive are discussed. 1. V.K. Gusev, …, V.E. Golant, et al., Nucl. Fusion 41, No 7, (2001), to be published

Plasmon dispersion in a multilayer solid torus in terms of three-term vector recurrence relations and matrix continued fractions

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

Garapati, K. V.; Bagherian, M.; Passian, A.

Toroidal confinement, which has played a crucial role in magnetized plasmas and Tokamak physics, is emerging as an effective means to obtain useful electronic and optical response in solids. In particular, excitation of surface plasmons in metal nanorings by photons or electrons finds important applications due to the engendered field distribution and electromagnetic energy confinement. However, in contrast to the case of a plasma, often the solid nanorings are multilayered and/or embedded in a medium. The non-simply connected geometry of the torus results in surface modes that are not linearly independent. A three-term difference equation was recently shown to arisemore » when seeking the nonretarded plasmon dispersion relations for a stratified solid torus (Garapati et al 2017 Phys. Rev. B 95 165422). The reported generalized plasmon dispersion relations are here investigated in terms of the involved matrix continued fractions and their convergence properties including the determinant forms of the dispersion relations obtained for computing the plasmon eigenmodes. We also present the intricacies of the derivation and properties of the Green's function employed to solve the three term amplitude equation that determines the response of the toroidal structure to arbitrary external excitations.« less

Groundbased Observations of Io [OI]6300 A Emission During the Galileo 124, 125, and Cassini Encounters

NASA Technical Reports Server (NTRS)

Oliversen, R. J.; Morgenthaler, J. P.; Scherb, F.; Woodward, R. C.; Smyth, W. H.; Lupie, O. L.

2003-01-01

For the past 12 years, we have conducted a synoptic study of [OI] 6300 A emission from Io using the high-resolution (R 120,000) stellar spectrograph at the National Solar Observatory McMath-Pierce telescope. We showed in a recent paper that this emission allows us to use Io as a localized probe of the three-dimensional plasma torus structure. We report on selected recent spectroscopic observations of Io [OI] 6300 A emission obtained during the Galileo I24 (1999-Oct-11) and I25 (1999-Nov-26) encounters with Io and the Cassini Jupiter encounter (closest approach 2000-Dec-30). The exposure time for each spectrum was 15 minutes, with a 5.2 x 5.2 aperture centered on Io. We obtained over 100 spectra for the I24 encounter during 1999 October 9-13, over 100 spectra for the I25 encounter during 1999 November 24-30, and for the Cassini Jupiter flyby almost 600 spectra from 2000 December to 2001 January 21. We use our database of observations to track long- and short-term variations in torus structure. We compare our results to Galileo, Cassini, HST, and other groundbased contemporaneous observations to gain insight into torus variability and structure.

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

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

Chan, Chi-Ho; Krolik, Julian H.

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply towardmore » the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.« less

Computational fluid dynamics models of conifer bordered pits show how pit structure affects flow.

PubMed

Schulte, Paul J

2012-02-01

• The flow of xylem sap through conifer bordered pits, particularly through the pores in the pit membrane, is not well understood, but is critical for an understanding of water transport through trees. • Models solving the Navier-Stokes equation governing fluid flow were based on the geometry of bordered pits in black spruce (Picea mariana) and scanning electron microscopy images showing details of the pores in the margo of the pit membrane. • Solutions showed that the pit canals contributed a relatively small fraction of resistance to flow, whereas the torus and margo pores formed a large fraction, which depended on the structure of the individual pit. The flow through individual pores in the margo was strongly dependent on pore area, but also on the radial location of the pore with respect to the edge of the torus. • Model results suggest that only a few per cent of the pores in the margo account for nearly half of the flow and these pores tend to be located in the inner region of the margo where their contribution will be maximized. A high density of strands in outer portions of the margo (hence narrower pores) may be more significant for mechanical support of the torus. © 2011 The Author. New Phytologist © 2011 New Phytologist Trust.

A Pulsating X-Ray Hot Spot on Jupiter

NASA Technical Reports Server (NTRS)

Gladstone, G. R.; Waite, J. H.; Grodent, D. C.; Crary, F. J.; Elsner, R. F.; Weisskopf, M. C.; Majeed, T.; Lewis, W. S.; Jahn, J.-M.; Bhardwaj, A.;

Implications of depleted flux tubes in the Jovian magnetosphere

NASA Astrophysics Data System (ADS)

Russell, C. T.; Kivelson, M. G.; Kurth, W. S.; Gurnett, D. A.

2000-10-01

A rare but persistent phenomenon in the jovian magnetosphere is the occurrence of apparently depleted flux tubes, whose magnetic pressures are significantly above ambient levels. These flux tubes occur about 0.25% of the observing time in the region of the Io torus in the Galileo high resolution data. The importance of these tubes is that they can return to the inner magnetosphere the magnetic flux that has been convected radially outward with the iogenic plasma to the tail. The paucity of these tubes is consistent with the expected flux return rates if the tubes are moving inward at an average rate of about 5-10 km/s in the torus. Depleted flux tubes have yet to be observed inside of the Io orbit where the plasma beta is lower than in the hot torus. Estimates of the plasma density outside the tube from plasma wave measurements enable the average perpendicular temperature to be obtained from the magnetic field change. Extrapolating this temperature back to Io, we obtain an average ion temperature of approximately 60 eV. These values are generally consistent with earlier Voyager observations but on the low side of their range of uncertainty, and agree quite well with contemporaneous Galileo measurements where these are available.

Implications of Depleted flux Tubes in the Jovian Magnetosphere

NASA Technical Reports Server (NTRS)

Russell, C. T.; Kivelson, M. G.; Kurth, W. S.; Gurnett, D. A.

2000-01-01

A rare but persistent phenomenon in the jovian magnetosphere is the occurrence of apparently depleted flux tubes, whose magnetic pressures are significantly above ambient levels. These flux tubes occur about 0.25% of the observing time in the region of the Io torus in the Galileo high resolution data. The importance of these tubes is that they can return to the inner magnetosphere the magnetic flux that has been convected radially outward with the iogenic plasma to the tail. The paucity of these tubes is consistent with the expected flux return rates if the tubes are moving inward at an average rate of about 5-10 km/s in the torus. Depleted flux tubes have yet to be observed inside of the lo orbit where the plasma beta is lower than in the hot torus. Estimates of the plasma density outside the tube from plasma wave measurements enable the average perpendicular temperature to be obtained from the magnetic field change. Extrapolating this temperature back to lo, we obtain an average ion temperature of approximately 60 eV. These values are generally consistent with earlier Voyager observations but on the low side of their range of uncertainty, and agree quite well with contemporaneous Galileo measurements where these are available.

Toroidal Geometry Stabilizing a Latitudinal Ring of Point Vortices on a Torus

NASA Astrophysics Data System (ADS)

Sakajo, Takashi; Shimizu, Yuuki

2018-06-01

We carry out the linear stability analysis of a polygonal ring configuration of N point vortices, called an N-ring, along the line of latitude θ _0 on a torus with the aspect ratio α . Deriving a criterion for the stability depending on the parameters N, θ _0 and α , we reveal how the aspect ratio α contributes to the stability of the N-ring. While the N-ring necessarily becomes unstable when N is sufficiently large for fixed α , the stability is closely associated with the geometric property of the torus for variable α ; for low aspect ratio α ˜ 1, N=7 is a critical number determining the stability of the N-ring when it is located along a certain range of latitudes, which is an analogous result to those in a plane and on a sphere. On the other hand, the stability is determined by the sign of curvature for high aspect ratio α ≫ 1. That is to say, the N-ring is neutrally stable if it is located on the inner side of the toroidal surface with a negative curvature, while the N-ring on its outer side with a positive curvature is unstable. Furthermore, based on the linear stability analysis, we describe nonlinear evolution of the N-ring when it becomes unstable. It is difficult to deal with this problem, since the evolution equation of the N point vortices is formulated as a Hamiltonian system with N degrees of freedom, which is in general non-integrable. Thus, we reduce the Hamiltonian system to a simple integrable system by introducing a cyclic symmetry. Owing to this reduction, we successfully find some periodic orbits in the reduced system, whose local bifurcations and global transitions for variable α are characterized in terms of the fundamental group of the torus.

High spatial resolution of the mid-infrared emission of the Compton-thick type 2 Seyfert galaxy, Markarian 3

NASA Astrophysics Data System (ADS)

Sales, Dinalva A.; Ruschel-Dutra, D.; Pastoriza, M. G.; Riffel, R.; Winge, Cláudia

2014-06-01

The mid-infrared (MIR) spectra observed with Gemini/Michelle have been used to study the nuclear region of the Compton-thick type 2 Seyfert galaxy, Markarian 3 (Mrk 3), at a spatial resolution of ˜200 pc. No polycyclic aromatic hydrocarbon emission bands were detected in the N-band spectrum of Mrk 3. However, intense [Ar III] 8.99 μm, [S IV] 10.5 μm and [Ne II] 12.8 μm ionic emission lines, as well as a silicate absorption feature at 9.7 μm, have been found in the nuclear extraction (˜200 pc). We also present a subarcsecond-resolution Michelle N-band image of Mrk 3, which resolves its circumnuclear region. This diffuse MIR emission shows up as a wing towards the east-west direction, closely aligned with the S-shape of the narrow-line region observed in the optical [O III] λ5007Å image from the Faint Object Camera onboard the Hubble Space Telescope. The nuclear continuum spectrum can be well represented by a theoretical torus spectral energy distribution, suggesting that the nucleus of Mrk 3 might host a dusty toroidal structure, as predicted by the unified model of an active galactic nucleus (AGN). In addition, the hydrogen column density (N_H= 4.8^{+3.3}_{-3.1}× 10^{23} cm-2) estimated with a torus model for Mrk 3 is consistent with the value derived from X-ray spectroscopy. The torus model geometry of Mrk 3 is similar to that of NGC 3281 (both are Compton-thick galaxies), confirmed through fitting the 9.7-μm silicate band profile. These results might provide further evidence that silicate-rich dust can be associated with the AGN torus and might also be responsible for the absorption observed at X-ray wavelengths in those galaxies.

First X-ray Statistical Tests for Clumpy-Torus Models: Constraints from RXTEmonitoring of Seyfert AGN

NASA Astrophysics Data System (ADS)

Markowitz, Alex; Krumpe, Mirko; Nikutta, R.

2016-06-01

In two papers (Markowitz, Krumpe, & Nikutta 2014, and Nikutta et al., in prep.), we derive the first X-ray statistical constraints for clumpy-torus models in Seyfert AGN by quantifying multi-timescale variability in line of-sight X-ray absorbing gas as a function of optical classification.We systematically search for discrete absorption events in the vast archive of RXTE monitoring of 55 nearby type Is and Compton-thin type IIs. We are sensitive to discrete absorption events due to clouds of full-covering, neutral/mildly ionized gas transiting the line of sight. Our results apply to both dusty and non-dusty clumpy media, and probe model parameter space complementary to that for eclipses observed with XMM-Newton, Suzaku, and Chandra.We detect twelve eclipse events in eight Seyferts, roughly tripling the number previously published from this archive. Event durations span hours to years. Most of our detected clouds are Compton-thin, and most clouds' distances from the black hole are inferred to be commensurate with the outer portions of the BLR or the inner regions of infrared-emitting dusty tori.We present the density profiles of the highest-quality eclipse events; the column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidallysheared. We discuss implications for cloud distributions in the context of clumpy-torus models. We calculate eclipse probabilities for orientation-dependent Type I/II unification schemes.We present constraints on cloud sizes, stability, and radial distribution. We infer that clouds' small angular sizes as seen from the SMBH imply 107 clouds required across the BLR + torus. Cloud size is roughly proportional to distance from the black hole, hinting at the formation processes (e.g., disk fragmentation). All observed clouds are sub-critical with respect to tidal disruption; self-gravity alone cannot contain them. External forces, such as magnetic fields or ambient pressure, are needed to contain them; otherwise, clouds must be short-lived.

Systematic Variability of the He+ Pickup Ion Velocity Distribution Function Observed with SOHO/CELIAS/CTOF

NASA Astrophysics Data System (ADS)

Taut, A.; Drews, C.; Berger, L.; Wimmer-Schweingruber, R. F.

2015-12-01

The 1D Velocity Distribution Function (VDF) of He+ pickup ions shows two distinct populations that reflect the sources of these ions. The highly suprathermal population is the result of the ionization and pickup of almost resting interstellar neutrals that are injected into the solar wind as a highly anisotropic torus distribution. The nearly thermalized population is centered around the solar wind bulk speed and is mainly attributed to inner-source pickup ions that originate in the inner heliosphere. It is generally believed that the initial torus distribution of interstellar pickup ions is rapidly isotropized by resonant wave-particle interactions, but recent observations by Drews et al. (2015) of a torus-like VDF strongly limit this isotropization. This in turn means that more observational data is needed to further characterize the kinetic behavior of pickup ions. In this study we use data from the Charge-Time-Of-Flight sensor on-board SOHO. As this sensor offers unrivaled counting statistics for He+ together with a sufficient mass-per-charge resolution it is well-suited for investigating the He+ VDF on comparatively short timescales. We combine this data with the high resolution magnetic field data from WIND via an extrapolation to the location of SOHO. With this combination of instruments we investigate the He+ VDF for time periods of different solar wind speeds, magnetic field directions, and wave power. We find a systematic trend of the short-term He+ VDF with these parameters. Especially by varying the considered magnetic field directions we observe a 1D projection of the anisotropic torus-like VDF. In addition, we investigate stream interaction regions and coronal mass ejections. In the latter we observe an excess of inner-source He+ that is accompanied by a significant increase of heavy pickup ion count rates. This may be linked to the as yet ill understood production mechanism of inner-source pickup ions.

On the Anisotropy of the He+, C+, O+, and Ne+ Pickup Ion Velocity Distribution Function: STEREO PLASTIC Observations

NASA Astrophysics Data System (ADS)

Taut, A.; Drews, C.; Berger, L.; Peleikis, T.; Wimmer-Schweingruber, R. F.

2015-12-01

PickUp Ions (PUIs) are typically characterized by (1) their almost exclusively single charge state, (2) a highly non-thermal and anisotropic Velocity Distribution Function (VDF) [Drews et al., 2015], and (3) an extended source population of neutral atoms somewhere between the observer and the Sun. The origin of pickup ions ranges from sources only several solar radii away from the Sun, the so-called inner-source of pickup ions, up to a distance of several hundreds of astronomical units, the local interstellar medium. Their continuous production inside the heliosphere and complex interactions with the magnetized solar wind plasma leads to the development of non-thermal, anisotropic features of both the solar wind and pickup ion velocity distribution functions. In this study, we present observations of the VDF of He+, C+, N+, O+ and Ne+ pickup ions with PLASTIC on STEREO A. We have found a PUI flux increase during perpendicular configurations of the local magnetic field that is generally linked to the existence of a so-called torus-distribution [Drews et al., 2015] which is attributed to the production of PUIs close to the observer. A comparison of the PUI VDF between radial and perpendicular configurations of the local magnetic field vector is used to quantify the anisotropy of the PUI VDF and thereby enables us to estimate the mean free path for pitch-angle scattering of He, C, N, O and Ne pickup ions without the necessity of an over-simplified heliospheric model to describe the PUI phase space transport. Our results show a clear signature of a C+ torus signature at 1 AU as well as significant differences between the anisotropies of the He+ and O+ VDF. We will discuss our results in the light of recent studies about the nature of the inner-source of PUIs [Berger et al., 2015] and observations of the 2D VDF of He+[Drews et al., 2015]. Figure Caption: Velocity space diagrams of a pickup ion torus distribution as a (vx-vy)-projection (top left panel) and in the vz = 0 km/s plane (top right) are shown for magnetic configuration in which B is almost perpendicular. The bottom two panels show the torus distribution under the influence of pitch-angle scattering (right) and adiabatic cooling (left). To illustrate the torus character of the distribution the (vx-vy)-plane is slightly tilted in this diagram.

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

Shaing, K. C.; Peng, Yueng Kay Martin

Transport theory for potato orbits in the region near the magnetic axis in an axisymmetric torus such as tokamaks and spherical tori is extended to the situation where the toroidal flow speed is of the order of the sonic speed as observed in National Spherical Torus Experiment [E. J. Synakowski, M. G. Bell, R. E. Bell et al., Nucl. Fusion 43, 1653 (2003)]. It is found that transport fluxes such as ion radial heat flux, and bootstrap current density are modified by a factor of the order of the square of the toroidal Mach number. The consequences of the orbitmore » squeezing are also presented. The theory is developed for parabolic (in radius r) plasma profiles. A method to apply the results of the theory for the transport modeling is discussed.« less

Three-dimensional observation of an helical hot structure during a sawtooth crash in the WT-3 tokamak.

PubMed

Yamaguchi, S; Igami, H; Tanaka, H; Maekawa, T

2004-07-23

Sawtooth crashes in an Ohmically heated plasma in the WT-3 tokamak have been observed by using soft x-ray computer tomography at three different poloidal cross sections around the torus. Initially, collapsing proceeds slowly with keeping the helical structure of an m = 1/n = 1 hot core around the torus. It accelerates as the helical hot structure is strongly deformed and fades away in the manner that the hot core at the high field side becomes obscure and disappears, while that at the low field side is deformed into a thin crescent aligned along the inversion circle, which survives even at the completion of the crash. Copyright 2004 The American Physical Society

Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

NASA Astrophysics Data System (ADS)

Foley, E. L.; Levinton, F. M.

2013-04-01

The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

Initial operation of the NSTX-Upgrade real-time velocity diagnostic

DOE PAGES

Podestà, M.; Bell, R. E.

2016-11-03

A real-time velocity (RTV) diagnostic based on active charge-exchange recombination spectroscopy is now operational on the National Spherical Torus Experiment-Upgrade (NSTX-U) spherical torus (Menard et al 2012 Nucl. Fusion 52 083015). We designed the system in order to supply plasma velocity data in real time to the NSTX-U plasma control system, as required for the implementation of toroidal rotation control. Our measurements are available from four radii at a maximum sampling frequency of 5 kHz. Post-discharge analysis of RTV data provides additional information on ion temperature, toroidal velocity and density of carbon impurities. Furthermore, examples of physics studies enabled bymore » RTV measurements from initial operations of NSTX-U are discussed.« less

Demonstration of Tokamak Ohmic Flux Saving by Transient Coaxial Helicity Injection in the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Raman, R.; Mueller, D.; Nelson, B. A.; Jarboe, T. R.; Gerhardt, S.; Kugel, H. W.; Leblanc, B.; Maingi, R.; Menard, J.; Ono, M.; Paul, S.; Roquemore, L.; Sabbagh, S.; Soukhanovskii, V.

2010-03-01

Transient coaxial helicity injection (CHI) started discharges in the National Spherical Torus Experiment (NSTX) have attained peak currents up to 300 kA and when coupled to induction, it has produced up to 200 kA additional current over inductive-only operation. CHI in NSTX has shown to be energetically quite efficient, producing a plasma current of about 10 A/J of capacitor bank energy. In addition, for the first time, the CHI-produced toroidal current that couples to induction continues to increase with the energy supplied by the CHI power supply at otherwise similar values of the injector flux, indicating the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.

A large deviations principle for stochastic flows of viscous fluids

NASA Astrophysics Data System (ADS)

Cipriano, Fernanda; Costa, Tiago

2018-04-01

We study the well-posedness of a stochastic differential equation on the two dimensional torus T2, driven by an infinite dimensional Wiener process with drift in the Sobolev space L2 (0 , T ;H1 (T2)) . The solution corresponds to a stochastic Lagrangian flow in the sense of DiPerna Lions. By taking into account that the motion of a viscous incompressible fluid on the torus can be described through a suitable stochastic differential equation of the previous type, we study the inviscid limit. By establishing a large deviations principle, we show that, as the viscosity goes to zero, the Lagrangian stochastic Navier-Stokes flow approaches the Euler deterministic Lagrangian flow with an exponential rate function.

Voyager 1 planetary radio astronomy observations near jupiter.

PubMed

Warwick, J W; Pearce, J B; Riddle, A C; Alexander, J K; Desch, M D; Kaiser, M L; Thieman, J R; Carr, T D; Gulkis, S; Boischot, A; Harvey, C C; Pedersen, B M

1979-06-01

We report results from the first low-frequency radio receiver to be transported into the Jupiter magnetosphere. We obtained dramatic new information, both because Voyager was near or in Jupiter's radio emission sources and also because it was outside the relatively dense solar wind plasma of the inner solar system. Extensive radio spectral arcs, from above 30 to about 1 megahertz, occurred in patterns correlated with planetary longitude. A newly discovered kilometric wavelength radio source may relate to the plasma torus near Io's orbit. In situ wave resonances near closest approach define an electron density profile along the Voyager trajectory and form the basis for a map of the torus. Detailed studies are in progress and are out-lined briefly.

Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source.

PubMed

Hossack, Aaron C; Firman, Taylor; Jarboe, Thomas R; Prager, James R; Victor, Brian S; Wrobel, Jonathan S; Ziemba, Timothy

2013-10-01

A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2-3) × 10(19) m(-3) to 1 × 10(19) m(-3). Deuterium spheromak formation is possible with density as low as 2 × 10(18) m(-3). The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.

Studies for the Loss of Atomic and Molecular Species from Io

NASA Technical Reports Server (NTRS)

Smyth, William H.

1998-01-01

Updated neutral emission rates for electron impact excitation of atomic oxygen and sulfur based upon the Collisional Radiative Equilibrium (COREQ) model have been incorporated in the neutral cloud models. An empirical model for the Io plasma torus wake has also been added in the neutral cloud model to describe important enhancements in the neutral emission rates and lifetime rates in this spatial region. New insights into Io's atmosphere and its interaction with the plasma torus are discussed. These insights are based upon an initial comparison of simultaneous lo observations on October 14, 1997, for [0I] 6300 Angstrom emissions acquired by groundbased facilities and several ultraviolet emissions acquired by HST/STIS in the form of high-spatial- resolution images for atomic oxygen and sulfur.

Implications of Voyager data for energetic ion erosion of the icy satellites of Saturn

NASA Technical Reports Server (NTRS)

Lanzerotti, L. J.; Maclennan, C. G.; Brown, W. L.; Johnson, R. E.; Barton, L. A.; Reimann, C. T.; Garrett, J. W.; Boring, J. W.

1983-01-01

The possible production of a neutral-particle torus by magnetosphere-particle sputtering of the icy satellites (Enceladus, Tethys, Dione, Rhea) of Saturn is discussed. Particle spectra from the Voyager low-energy-charged-particle experiment are used together with laboratory-derived erosion rates and velocity distributions for the ejected species. An extended torus region in the inner magnetosphere of Saturn is expected, with H2O escape fluxes in the vicinities of the satellites varying from about 2 to 7 x 10 to the 7th mol/sq cm sec for incident protons and from about 6 to 14 x 10 to the 9th mol/sq cm sec if the incident ions are all oxygen.

IUE spectrum of the IO torus - Identification of the 5S2-3P2,1 transition of S III

NASA Technical Reports Server (NTRS)

Moos, H. W.; Durrance, S. T.; Skinner, T. E.; Feldman, P. D.; Bertaux, J.-L.; Festou, M. C.

1983-01-01

A spectrum of a much higher quality than previously available has been obtained which shows emission features arising from S(+), S(++), S(+++), and an upper limit for O(++). The well-defined splitting of the 1729 A feature is seen as confirming its tentative identification as semiforbidden S III 5S2(0)-3P2,1. The lower contamination of S III 1199 A by H I 1216 A than in most previous IUE spectra of the Io torus makes possible an estimate of the S III 1729 A collision strength. The variation of these features with temperature and their possible presence in spectra of nebulae are discussed.

A collective scattering system for measuring electron gyroscale fluctuations on the National Spherical Torus Experiment.

PubMed

Smith, D R; Mazzucato, E; Lee, W; Park, H K; Domier, C W; Luhmann, N C

2008-12-01

A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas. The system measures fluctuations with k( perpendicular)rho(e) less, similar0.6 and k( perpendicular) less, similar20 cm(-1). Up to five distinct wavenumbers are measured simultaneously, and the large toroidal curvature of NSTX plasmas provides enhanced spatial localization. Steerable optics can position the scattering volume throughout the plasma from the magnetic axis to the outboard edge. Initial measurements indicate rich turbulent dynamics on the electron gyroscale. The system will be a valuable tool for investigating the connection between electron temperature gradient turbulence and electron thermal transport in NSTX plasmas.

Conceptual study of the cryocascade for pumping, separation and recycling of ITER torus exhaust

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

Mack, A.; Perinic, D.

1994-12-31

For pumping, separation and recycling of the ITER plasma exhaust, a pumping system working reliably under ambient and operating conditions of the ITER reactor is required. The pump is exposed to a magnetic field of about 3 T and has to be resistant to radioactive irradiation of 10{sup 9} rad. In the burn and dwell phase, a gas mixture consisting of hydrogen isotopes, helium ash and impurities has to be pumped at the pressure range of 10{sup {minus}2} - 10{sup {minus}1} mbar. Within the framework of the European Fusion Technology Programme, the concept of a primary cryopump for use inmore » ITER is being prepared at KfK. The cryocascade concept is planned to include three pump stages. These pump stages, which are connected in series, consist of individual chambers that may be separated from each other by means of cold valves. In the first stage, the impurities of the reactor exhaust gas are frozen out at 20-30 K. Settling of the hydrogen isotopes H/D/T on the 5 K cryosurfaces takes place in the second stage. This stage is made up of two parallel chambers, which can be switched from the pumping to the regeneration mode or vice versa. The helium fraction is bound in the downstream 5 K adsorption stage.« less

Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

NASA Technical Reports Server (NTRS)

Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

2004-01-01

One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

X-Ray Probes of Jupiter's Auroral Zones, Galilean Moons, and the Io Plasma Torus

NASA Technical Reports Server (NTRS)

Elsner, R. F.; Ramsey, B. D.; Swartz, D. A.; Rehak, P.; Waite, J. H., Jr.; Cooper, J. F.; Johnson, R. E.

2005-01-01

Remote observations from the Earth orbiting Chandra X-ray Observatory and the XMM-Newton Observatory have shown the the Jovian system is a rich and complex source of x-ray emission. The planet's auroral zones and its disk are powerful sources of x-ray emission, though with different origins. Chandra observations discovered x-ray emission from the Io plasma torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is due to bombardment of their surfaces by highly energetic magnetospheric protons, and oxygen and sulfur ions, producing fluorescent x-ray emission lines from the elements in their surfaces against an intense background continuum. Although very faint when observed from Earth orbit, an imaging x-ray spectrometer in orbit around the icy Galilean moons would provide a detail mapping of the elemental composition in their surfaces. Here we review the results of Chandra and XMM-Newton observations of the Jovian system and describe the characteristics of X-MIME, an imaging x-ray spectrometer undergoing study for possible application to future missions to Jupiter such as JIMO. X-MIME has the ultimate goal of providing detailed high-resolution maps of the elemental abundances of the surfaces of Jupiter's icy moons and Io, as well as detailed study of the x-ray mission from the Io plasma torus, Jupiter's auroral zones, and the planetary disk.

Energetic Particles in the far and near Environment of Pluto

NASA Astrophysics Data System (ADS)

Kollmann, P.; Hill, M. E.; McNutt, R. L., Jr.; Brown, L. E.; Kusterer, M. B.; Vandegriff, J. D.; Smith, H. T.; Mitchell, D. G.; Haggerty, D. K.; Bagenal, F.; Krimigis, S. M.; Lisse, C. M.; Delamere, P. A.; Elliott, H. A.; Horanyi, M.; McComas, D. J.; Piquette, M. R.; Poppe, A. R.; Sidrow, E. J.; Strobel, D. F.; Szalay, J.; Valek, P. W.; Weidner, S.; Zirnstein, E.; Ennico Smith, K.; Olkin, C.; Weaver, H. A., Jr.; Young, L. A.; Stern, A.

2015-12-01

The New Horizons spacecraft was launched in 2006, passed Jupiter and its magnetotail, took continuous measurements in the solar wind throughout the recent years, and flew by Pluto in July 2015. The onboard PEPSSI instrument measures ion and electron intensities, masses, and energies in the keV to MeV range. The closest approach distance to Pluto was 11 Pluto radii, inside the orbit of Charon. Data taken near Pluto is downlinked throughout August. We will present analysis of this data and set it into context with previous measurements. We expect a number of interesting particle structures around Pluto. Parts of Pluto's molecular nitrogen atmosphere is escaping and will co-orbit with Pluto, potentially forming a partial gas torus. This torus can be additionally sourced by other Kuiper belt objects. The neutrals are eventually ionized and pick-up by the solar wind brings them into the PEPSSI energy range. The measured ion densities can be used to constrain the Pluto torus. Pluto is not expected to have an intrinsic magnetic field, but the energetic particle data can be used to infer its properties, if any. Pluto interacts instead with the solar wind via the pick-up of its ions and the magnetic fields created by currents in its ionosphere. The relative role of these mechanisms can be revealed by the flyby data and directly compared to data that was taken at Jupiter with identical instrumentation.

Reduced model simulations of the scrape-off-layer heat-flux width and comparison with experiment

DOE PAGES

Myra, J. R.; Russell, D. A.; D’Ippolito, D. A.; ...

2011-01-01

Reduced model simulations of turbulence in the edge and scrape-off-layer (SOL) region of a spherical torus or tokamak plasma are employed to address the physics of the scrape-off-layer heat flux width. The simulation model is an electrostatic two-dimensional fluid turbulence model, applied in the plane perpendicular to the magnetic field at the outboard midplane of the torus. The model contains curvature-driven-interchange modes, sheath losses, and both perpendicular turbulent diffusive and convective (blob) transport. These transport processes compete with classical parallel transport to set the SOL width. Midplane SOL profiles of density, temperature and parallel heat flux are obtained from themore » simulation and compared with experimental results from the National Spherical Torus Experiment (NSTX) to study the scaling of the heat flux width with power and plasma current. It is concluded that midplane turbulence is the main contributor to the SOL heat flux width for the low power H-mode discharges studied, while additional physics is required to explain the plasma current scaling of the SOL heat flux width observed experimentally in higher power discharges. Intermittent separatrix spanning convective cells are found to be the main mechanism that sets the near-SOL width in the simulations. The roles of sheared flows and blob trapping vs. emission are discussed.« less

Arithmetic functions in torus and tree networks

DOEpatents

Bhanot, Gyan; Blumrich, Matthias A.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos M.

2007-12-25

Methods and systems for performing arithmetic functions. In accordance with a first aspect of the invention, methods and apparatus are provided, working in conjunction of software algorithms and hardware implementation of class network routing, to achieve a very significant reduction in the time required for global arithmetic operation on the torus. Therefore, it leads to greater scalability of applications running on large parallel machines. The invention involves three steps in improving the efficiency and accuracy of global operations: (1) Ensuring, when necessary, that all the nodes do the global operation on the data in the same order and so obtain a unique answer, independent of roundoff error; (2) Using the topology of the torus to minimize the number of hops and the bidirectional capabilities of the network to reduce the number of time steps in the data transfer operation to an absolute minimum; and (3) Using class function routing to reduce latency in the data transfer. With the method of this invention, every single element is injected into the network only once and it will be stored and forwarded without any further software overhead. In accordance with a second aspect of the invention, methods and systems are provided to efficiently implement global arithmetic operations on a network that supports the global combining operations. The latency of doing such global operations are greatly reduced by using these methods.

Flow profile measurement with multi-Mach probes on the HIST spherical torus device

NASA Astrophysics Data System (ADS)

Hashimoto, S.; Nishioka, T.; Ando, K.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2008-11-01

Role of plasma flow during MHD relaxation and magnetic reconnection processes is still underlying physics. The HIST spherical torus can generate various spherical torus (ST) configurations by changing the external toroidal magnetic field. Especially, the flipped ST (F-ST) configuration has been for the first time found in the HIST device [1]. In the present study, plasma flow measurements were performed by multi-Mach probes in the ST and the F-ST configurations. In addition, the measured plasma flow was compared with that evaluated by an ion Doppler spectrometer (IDS) system and plasma images measured by a high-speed camera. As the result, it was shown that the toroidal plasma flow (˜ 20 km/s) at the location far from the plasma gun was clearly reversed after the transition from the ST to the F-ST. However, the direction of the toroidal flow was not changed near the plasma gun. Therefore, it can be considered that there are flipped and non-reversal regions in the plasma. The result agrees well with a magnetic configuration predicted by magnetic field measurements. The plasma images measured by the high-speed camera also indicated that a helically twisted structure appeared from the gun region, and it localized at the edge region. [1] M. Nagata et al., Phys. Rev. Lett. 90, pp. 225001-225004 (2003).

Ion flow measurements during the MHD relaxation processes in the HIST spherical torus device

NASA Astrophysics Data System (ADS)

Nishioka, T.; Hashimoto, S.; Ando, K.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2008-11-01

Plasma flow is one of the key roles in self-organization and magnetic reconnection processes of helicity-driven spherical torus (ST) and spheromak. The HIST spherical torus can form the standard ST and the flipped ST plasmas by utilizing the variation of the external toroidal field coil current. The flipped ST plasma can be generated by changing the polarity of the toroidal magnetic field during the standard ST discharge [1]. We have developed an ion Doppler spectrometer (IDS) system using a compact 16 channel photomultiplier tube (PMT) in order to measure the spatial profile of ion temperature and rotation velocity in the HIST device. The IDS system consists of a light collection system including optical fibers, 1 m-spectrometer and the PMT detector. As the results, it was observed that ion velocity was about 10 km/s in the same direction as the toroidal current and ExB direction in the standard ST discharge. The observed ion velocity agrees with Mach probe measurements. During the transition from the standard ST to the flipped ST state, the ion temperature was fluctuated and increased. The result implies an ion heating during magnetic reconnections. In addition, the toroidal direction of the ion flow was reversed. The detail physics of the observed phenomenon will be shown. [1] M. Nagata et al., Phys Rev. Lett. 90, pp. 225001-225004 (2003).

Solitons on Noncommutative Torus as Elliptic Calogero-Gaudin Models, Branes and Laughlin Wave Functions

NASA Astrophysics Data System (ADS)

Hou, Bo-Yu; Peng, Dan-Tao; Shi, Kang-Jie; Yue, Rui-Hong

For the noncommutative torus T, in the case of the noncommutative parameter θ = (Z)/(n), we construct the basis of Hilbert space Hn in terms of θ functions of the positions zi of n solitons. The wrapping around the torus generates the algebra An, which is the Zn × Zn Heisenberg group on θ functions. We find the generators g of a local elliptic su(n), which transform covariantly by the global gauge transformation of An. By acting on Hn we establish the isomorphism of An and g. We embed this g into the L-matrix of the elliptic Gaudin and Calogero-Moser models to give the dynamics. The moment map of this twisted cotangent sunT) bundle is matched to the D-equation with the Fayet-Illiopoulos source term, so the dynamics of the noncommutative solitons become that of the brane. The geometric configuration (k, u) of the spectral curve det|L(u) - k| = 0 describes the brane configuration, with the dynamical variables zi of the noncommutative solitons as the moduli T⊗ n/Sn. Furthermore, in the noncommutative Chern-Simons theory for the quantum Hall effect, the constrain equation with quasiparticle source is identified also with the moment map equation of the noncommutative sunT cotangent bundle with marked points. The eigenfunction of the Gaudin differential L-operators as the Laughlin wave function is solved by Bethe ansatz.

The structure and stability of orbits in Hoag-like ring systems

NASA Astrophysics Data System (ADS)

Bannikova, Elena Yu

2018-05-01

Ring galaxies are amazing objects exemplified by the famous case of Hoag's Object. Here the mass of the central galaxy may be comparable to the mass of the ring, making it a difficult case to model mechanically. In a previous paper, it was shown that the outer potential of a torus (ring) can be represented with good accuracy by the potential of a massive circle with the same mass. This approach allows us to simplify the problem of the particle motion in the gravitational field of a torus associated with a central mass by replacing the torus with a massive circle. In such a system, there is a circle of unstable equilibrium that we call `Lagrangian circle' (LC). Stable circular orbits exist only in some region limited by the last possible circular orbit related to the disappearance of the extrema of the effective potential. We call this orbit `the outermost stable circular orbit' (OSCO) by analogy with the innermost stable circular orbit (ISCO) in the relativistic case of a black hole. Under these conditions, there is a region between OSCO and LC where the circular motion is not possible due to the competition between the gravitational forces by the central mass and the ring. As a result, a gap in the matter distribution can form in Hoag-like system with massive rings.

FULL SPECTRAL SURVEY OF ACTIVE GALACTIC NUCLEI IN THE ROSSI X-RAY TIMING EXPLORER ARCHIVE

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

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu

2013-08-01

We have analyzed spectra for all active galactic nuclei (AGNs) in the Rossi X-ray Timing Explorer archive. We present long-term average values of absorption, Fe line equivalent width (EW), Compton reflection, and photon index, and calculate fluxes and luminosities in the 2-10 keV band for 100 AGN with sufficient brightness and overall observation time to yield high-quality spectral results. We compare these parameters across the different classifications of Seyferts and blazars. Our distributions of photon indices for Seyfert 1s and 2s are consistent with the idea that Seyferts share a common central engine; however, our distributions of Compton reflection humpmore » strengths do not support the classical picture of absorption by a torus and reflection off a Compton-thick disk with type depending only on inclination angle. We conclude that a more complex reflecting geometry such as a combined disk and torus or clumpy torus is likely a more accurate picture of the Compton-thick material. We find that Compton reflection is present in {approx}85% of Seyferts and by comparing Fe line EW's to Compton reflection hump strengths we have found that on average 40% of the Fe line arises in Compton thick material; however, this ratio was not consistent from object to object and did not seem to be dependent on optical classification.« less

AN OCCULTATION EVENT IN CENTAURUS A AND THE CLUMPY TORUS MODEL

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

Rivers, Elizabeth; Markowitz, Alex; Rothschild, Richard, E-mail: erivers@ucsd.edu

2011-12-15

We have analyzed 16 months of sustained monitoring observations of Centaurus A from the Rossi X-Ray Timing Explorer to search for changes in the absorbing column in the line of sight to the central nucleus. We present time-resolved spectroscopy which indicates that a discrete clump of material transited the line of sight to the central illuminating source over the course of {approx}170 days between 2010 August and 2011 February with a maximum increase in the column density of about 8.4 Multiplication-Sign 10{sup 22} cm{sup -2}. This is the best quality data of such an event that has ever been analyzedmore » with the shape of the ingress and egress clearly seen. Modeling the clump of material as roughly spherical with a linearly decreasing density profile and assuming a distance from the central nucleus commensurate with the dusty torus, we found that the clump would have a diameter of (1.4-2.4) Multiplication-Sign 10{sup 15} cm with a central number density of n{sub H} = (1.8-3.0) Multiplication-Sign 10{sup 7} cm{sup -3}. This is consistent with previous results for a similar (though possibly much longer) occultation event inferred in this source in 2003-2004 and supports models of the molecular torus as a clumpy medium.« less

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

Lazarus, E.A.; Attenberger, S.E.; Baylor, L.R.

The design of the Spherical Torus Experiment (STX) is discussed. The physics of the plasma are given in a magnetohydrodynamic model. The structural aspects and instrumentation of the device are described. 19 refs., 103 figs. (WRF)

Application of the Refined Integral Method in the mathematical modeling of drug delivery from one-layer torus-shaped devices.

PubMed

Helbling, Ignacio M; Ibarra, Juan C D; Luna, Julio A

2012-02-28

A mathematical modeling of controlled release of drug from one-layer torus-shaped devices is presented. Analytical solutions based on Refined Integral Method (RIM) are derived. The validity and utility of the model are ascertained by comparison of the simulation results with matrix-type vaginal rings experimental release data reported in the literature. For the comparisons, the pair-wise procedure is used to measure quantitatively the fit of the theoretical predictions to the experimental data. A good agreement between the model prediction and the experimental data is observed. A comparison with a previously reported model is also presented. More accurate results are achieved for small A/C(s) ratios. Copyright © 2011 Elsevier B.V. All rights reserved.

Latitudinal oscillations of plasma within the Io torus

NASA Technical Reports Server (NTRS)

Cummings, W. D.; Dessler, A. J.; Hill, T. W.

1980-01-01

The equilibrium latitude and the period of oscillations about this equilibrium latitude are calculated for a plasma in a centrifugally dominated tilted dipole magnetic field representing Jupiter's inner magnetosphere. It is found that for a hot plasma the equilibrium latitude in the magnetic equator, for a cold plasma it is the centrifugal equator, and for a warm plasma it is somewhere in between. An illustrative model is adopted in which atoms are sputtered from the Jupiter-facing hemisphere of Io and escape Io's gravity to be subsequently ionized some distance from Io. Finally, it is shown that ionization generally does not occur at the equilibrium altitude, and that the resulting latitudinal oscillations provide an explanation for the irregularities in electron concentration within the torus, as reported by the radioastronomy experiment aboard Voyager I.

Towards weakly constrained double field theory

NASA Astrophysics Data System (ADS)

Lee, Kanghoon

2016-08-01

We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon) transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

Properties of the Io plasma torus inferred from Voyager EUV data

NASA Technical Reports Server (NTRS)

Strobel, D. F.; Davis, J.

1980-01-01

A physical model for the Io plasma torus is constructed to explain the EUV radiative emission observed by the Voyager UV spectrometer. Electron impact excitation rate coefficients for electronic transitions of S III, S IV, O II and O III are calculated by the method of distorted waves (Davis, Kepple, and Blaha, 1976); these coefficients account for the asymmetric shape of the 686 A feature. It is concluded that the electron gas must have a distribution function with a non-Maxwellian tail. An approximate representation of the distribution function as two temperature components requires a cold component of 3.5-4 eV and density of 2000 per cu cm and a hot component of about 100 eV and density of 50-100 per cu cm to satisfy observational constraints.

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

Ogane, S.; Shikama, T., E-mail: shikama@me.kyoto-u.ac.jp; Hasuo, M.

In magnetically confined torus plasmas, the local emission intensity, temperature, and flow velocity of atoms in the inboard and outboard scrape-off layers can be separately measured by a passive emission spectroscopy assisted by observation of the Zeeman splitting in their spectral line shape. To utilize this technique, a near-infrared interference spectrometer optimized for the observation of the helium 2{sup 3}S–2{sup 3}P transition spectral line (wavelength 1083 nm) has been developed. The applicability of the technique to actual torus devices is elucidated by calculating the spectral line shapes expected to be observed in LHD and QUEST (Q-shu University Experiment with Steadymore » State Spherical Tokamak). In addition, the Zeeman effect on the spectral line shape is measured using a glow-discharge tube installed in a superconducting magnet.« less

Rarefaction Effects in Hypersonic Aerodynamics

NASA Astrophysics Data System (ADS)

Riabov, Vladimir V.

2011-05-01

The Direct Simulation Monte-Carlo (DSMC) technique is used for numerical analysis of rarefied-gas hypersonic flows near a blunt plate, wedge, two side-by-side plates, disk, torus, and rotating cylinder. The role of various similarity parameters (Knudsen and Mach numbers, geometrical and temperature factors, specific heat ratios, and others) in aerodynamics of the probes is studied. Important kinetic effects that are specific for the transition flow regime have been found: non-monotonic lift and drag of plates, strong repulsive force between side-by-side plates and cylinders, dependence of drag on torus radii ratio, and the reverse Magnus effect on the lift of a rotating cylinder. The numerical results are in a good agreement with experimental data, which were obtained in a vacuum chamber at low and moderate Knudsen numbers from 0.01 to 10.

Analysis of 100Mb/s Ethernet for the Whitney Commodity Computing Testbed

NASA Technical Reports Server (NTRS)

Fineberg, Samuel A.; Pedretti, Kevin T.; Kutler, Paul (Technical Monitor)

1997-01-01

We evaluate the performance of a Fast Ethernet network configured with a single large switch, a single hub, and a 4x4 2D torus topology in a testbed cluster of "commodity" Pentium Pro PCs. We also evaluated a mixed network composed of ethernet hubs and switches. An MPI collective communication benchmark, and the NAS Parallel Benchmarks version 2.2 (NPB2) show that the torus network performs best for all sizes that we were able to test (up to 16 nodes). For larger networks the ethernet switch outperforms the hub, though its performance is far less than peak. The hub/switch combination tests indicate that the NAS parallel benchmarks are relatively insensitive to hub densities of less than 7 nodes per hub.

The BlueGene/L supercomputer

NASA Astrophysics Data System (ADS)

Bhanota, Gyan; Chen, Dong; Gara, Alan; Vranas, Pavlos

2003-05-01

The architecture of the BlueGene/L massively parallel supercomputer is described. Each computing node consists of a single compute ASIC plus 256 MB of external memory. The compute ASIC integrates two 700 MHz PowerPC 440 integer CPU cores, two 2.8 Gflops floating point units, 4 MB of embedded DRAM as cache, a memory controller for external memory, six 1.4 Gbit/s bi-directional ports for a 3-dimensional torus network connection, three 2.8 Gbit/s bi-directional ports for connecting to a global tree network and a Gigabit Ethernet for I/O. 65,536 of such nodes are connected into a 3-d torus with a geometry of 32×32×64. The total peak performance of the system is 360 Teraflops and the total amount of memory is 16 TeraBytes.

Torus Knot Polynomials and Susy Wilson Loops

NASA Astrophysics Data System (ADS)

Giasemidis, Georgios; Tierz, Miguel

2014-12-01

We give, using an explicit expression obtained in (Jones V, Ann Math 126:335, 1987), a basic hypergeometric representation of the HOMFLY polynomial of ( n, m) torus knots, and present a number of equivalent expressions, all related by Heine's transformations. Using this result, the symmetry and the leading polynomial at large N are explicit. We show the latter to be the Wilson loop of 2d Yang-Mills theory on the plane. In addition, after taking one winding to infinity, it becomes the Wilson loop in the zero instanton sector of the 2d Yang-Mills theory, which is known to give averages of Wilson loops in = 4 SYM theory. We also give, using matrix models, an interpretation of the HOMFLY polynomial and the corresponding Jones-Rosso representation in terms of q-harmonic oscillators.

Highly excited electronic image states of metallic nanorings

PubMed Central

Fey, Christian; Jabusch, Henrik; Knörzer, Johannes; Schmelcher, Peter

2017-01-01

We study electronic image states around a metallic nanoring and show that the interplay between the attractive polarization force and a repulsive centrifugal force gives rise to Rydberg-like image states trapped several nanometers away from the surface. The nanoring is modeled as a perfectly conducting isolated torus whose classical electrostatic image potential is derived analytically. The image states are computed via a two-dimensional finite-difference scheme as solutions of the effective Schrödinger equation describing the outer electron subject to this image potential. These findings demonstrate not only the existence of detached image states around nanorings but allow us also to provide general criteria on the ring geometry, i.e., the aspect ratio of the torus, that need to be fulfilled in order to support such states. PMID:28527466

Anisotropy of the He+, C+, N+, O+, and Ne+ Pickup Ion Velocity Distribution Function

NASA Astrophysics Data System (ADS)

Drews, Christian; Berger, Lars; Taut, Andreas; Wimmer-Schweingruber, Robert F.

2016-04-01

Interstellar and inner-source PickUp Ions (PUIs) are produced by the ionization of neutral atoms that originate either outside or inside the heliosphere. Just after the ionization, the singly charged ions are picked up by the magnetized solar wind plasma and develop strong anisotropic toroidal features in their Velocity Distribution Functions (VDF). As the plasma parcel moves outward with the solar wind, the pickup-ion VDF gets more and more affected by resonant wave-particle interactions, changing heliospheric conditions, and plasma drifts, which lead to a gradual isotropization of the pickup ion VDF. Past investigations of the pickup ion torus distribution were limited to He+ pickup ions at 1 Astronomical Unit (AU). The aim of this study is to quantify the state of anisotropy of the He+, C+, N+, O+, and Ne+ pickup ion VDF at 1 AU. Changes between the state of anisotropy between PUIs of different mass-per charges can be used to estimate the significance of resonant wave particle interactions for the isotropization of their VDF, and to investigate the numerous simplifications that are generally made for the description of the phase space transport of PUIs. Pulse height analysis data by the PLAsma and SupraThermal Ion Composition instrument (PLASTIC) on board the Solar Terrestrial RElations Observatory Ahead (STEREO A) is used to obtain velocity spectra of He+, C+, N+, O+, and Ne+ relative to the solar wind, f(wsw). The wsw-spectra are sorted by two different configurations of the local magnetic field - one in which the torus distribution lies within the instrument's aperture, φ⊥, and one in which the torus distribution lies exclusively outside the instrument's field of view, φ∥. The ratio of the PUI spectra between φ⊥ and φ∥ is used to determine the degree of anisotropy of the PUI VDF. The data shows that the formation of a torus distribution at 1 AU is significantly more prominent for O+ (and N+) than for He+ (and Ne+). This cannot be explained by resonant wave-particle interactions as the sole mechanism for the isotropization of the PUI VDF. The anisotropy of the O+ VDF compared to He+ is highly fluctuating but consistently higher over an observation period of 6 years and therefore unlikely to be related to either specific heliospheric conditions or solar activity variations. To our surprise, we also found a clear signature of a C+ torus distribution at 1 AU very similar to the one of He+, although as an inner-source PUI, C+ should have a considerably different spectral and spatial injection pattern than interstellar PUIs.

Developing an Inflatable Solar Array

NASA Technical Reports Server (NTRS)

Malone, Patrick K.; Jankowski, Francis J.; Williams, Geoffery T.; Vendura, George J., Jr.

1992-01-01

Viewgraphs describing the development of an inflatable solar array as part of the Inflatable Torus Solar Array Technology (ITSAT) program are presented. Program phases, overall and subsystem designs, and array deployment are addressed.

Research on Orbital Plasma-Electrodynamics (ROPE)

NASA Technical Reports Server (NTRS)

Wu, S. T.; Wright, K.

1994-01-01

Since the development of probe theory by Langmuir and Blodgett, the problem of current collection by a charged spherically or cylindrically symmetric body has been investigated by a number of authors. This paper overviews the development of a fully three-dimensional particle simulation code which can be used to understand the physics of current collection in three dimensions and can be used to analyze data resulting from the future tethered satellite system (TSS). According to the TSS configurations, two types of particle simulation models were constructed: a simple particle simulation (SIPS) and a super particle simulation (SUPS). The models study the electron transient response and its asymptotic behavior around a three dimensional, highly biased satellite. The potential distribution surrounding the satellite is determined by solving Laplace's equation in the SIPS model and by solving Poisson's equation in the SUPS model. Thus, the potential distribution in space is independent of the density distribution of the particles in the SUPS model but it does depend on the density distribution of the particles in the SUPS model. The evolution of the potential distribution in the SUPS model is described. When the spherical satellite is charged to a highly positive potential and immersed in a plasma with a uniform magnetic field, the formation of an electron torus in the equatorial plane (the plane in perpendicular to the magnetic field) and elongation of the torus along the magnetic field are found in both the SIPS and the SUPS models but the shape of the torus is different. The areas of high potential that exist in the polar regions in the SUPS model exaggerate the elongation of the electron torus along the magnetic field. The current collected by the satellite for different magentic field strengths is investigated in both models. Due to the nonlinear effects present in SUPS, the oscillating phenomenon of the current collection curve during the first 10 plasma periods can be seen (this does not appear in SIPS). From the parametric studies, it appears that the oscillating phenomenon of the current collection curve occurs only when the magnetic field strength is less than 0.2 gauss for the present model.

On the 10 μm Silicate Feature in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Nikutta, Robert; Elitzur, Moshe; Lacy, Mark

2009-12-01

The 10 μm silicate feature observed with Spitzer in active galactic nuclei (AGNs) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped emission peaks shifted toward long wavelengths in several type 1 sources, and (3) is not seen in deep absorption in any source observed so far. We solve all three puzzles with our clumpy dust radiative transfer formalism. Addressing (1), we present the spectral energy distribution (SED) of SST1721+6012, the first type 2 quasar observed to show a clear 10 μm silicate feature in emission. Such emission arises in models of the AGN torus easily when its clumpy nature is taken into account. We constructed a large database of clumpy torus models and performed extensive fitting of the observed SED. We find that the cloud radial distribution varies as r -1.5 and the torus contains 2-4 clouds along radial equatorial rays, each with optical depth at visual ~60-80. The source bolometric luminosity is ~3 × 1012 Lsun. Our modeling suggests that lsim35% of objects with tori sharing these characteristics and geometry would have their central engines obscured. This relatively low obscuration probability can explain the clear appearance of the 10 μm emission feature in SST1721+6012 together with its rarity among other QSO2. Investigating (2), we also fitted the SED of PG1211+143, one of the first type 1 QSOs with a 10 μm silicate feature detected in emission. Together with other similar sources, this QSO appears to display an unusually broadened feature whose peak is shifted toward longer wavelengths. Although this led to suggestions of non-standard dust chemistry in these sources, our analysis fits such SEDs with standard galactic dust; the apparent peak shifts arise from simple radiative transfer effects. Regarding (3), we find additionally that the distribution of silicate feature strengths among clumpy torus models closely resembles the observed distribution, and the feature never occurs deeply absorbed. Comparing such distributions in several AGN samples we also show that the silicate emission feature becomes stronger in the transition from Seyfert to quasar luminosities.

The Compact Radio Sources in the Nucleus of NGC 1068

NASA Astrophysics Data System (ADS)

Roy, A. L.; Colbert, E. J. M.; Wilson, A. S.; Ulvestad, J. S.

1998-09-01

We report VLBA images of the nucleus of the Seyfert galaxy NGC 1068 at 1.7, 5, and 15 GHz, with resolutions between 3 and 10 mas (0.2-0.7 pc) and a sensitivity of ~106 K at all three frequencies. Our goals are to study the morphology of the radio emission at subparsec resolution and to investigate thermal gas in the putative obscuring disk or torus and in the narrow-line region clouds through free-free absorption of the radio emission. All four known radio components in the central arcsecond (S2, S1, C, and NE, from south to north) have been detected at either 1.7 or 5 GHz, or both. No radio emission was detected at 15 GHz. Component S1 is probably associated with the active nucleus, with radio emission originating from the inner edge of the obscuring torus according to Gallimore et al. Our observed flux densities at 1.7 and 5 GHz are in agreement with their thermal bremsstrahlung emission model, and we find that the nuclear radiation may be strong enough to heat the gas in S1 to the required temperature of ~4 × 106 K. The bremsstrahlung power would be 0.15(frefl/0.01) times the bolometric luminosity of the nucleus between 1014.6 and 1018.4 Hz (where frefl is the fraction of radiation reflected into our line of sight by the electron-scattering mirror) and so the model is energetically reasonable. We also discuss two other models for S1 that also match the observed radio spectrum: electron scattering by the torus of radio emission from a compact synchrotron self-absorbed source and synchrotron radiation from the torus itself. Components NE and S2 have spectra consistent with optically thin synchrotron emission, without significant absorption. Both of these components are elongated roughly perpendicular to the larger scale radio jet, suggesting that their synchrotron emission is related to transverse shocks in the jet or to bow shocks in the external medium. Component C has a nonthermal spectrum absorbed at low frequency. This absorption is consistent with free-free absorption by plasma with conditions typical of narrow-line region clouds.

DETERMINING THE COVERING FACTOR OF COMPTON-THICK ACTIVE GALACTIC NUCLEI WITH NuSTAR

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

Brightman, M.; Baloković, M.; Fuerst, F.

2015-05-20

The covering factor of Compton-thick (CT) obscuring material associated with the torus in active galactic nuclei (AGNs) is at present best understood through the fraction of sources exhibiting CT absorption along the line of sight (N{sub H} > 1.5 × 10{sup 24} cm{sup −2}) in the X-ray band, which reveals the average covering factor. Determining this CT fraction is difficult, however, due to the extreme obscuration. With its spectral coverage at hard X-rays (>10 keV), Nuclear Spectroscopic Telescope Array (NuSTAR) is sensitive to the AGNs covering factor since Compton scattering of X-rays off optically thick material dominates at these energies. Wemore » present a spectral analysis of 10 AGNs observed with NuSTAR where the obscuring medium is optically thick to Compton scattering, so-called CT AGNs. We use the torus models of Brightman and Nandra that predict the X-ray spectrum from reprocessing in a torus and include the torus opening angle as a free parameter and aim to determine the covering factor of the CT gas in these sources individually. Across the sample we find mild to heavy CT columns, with N{sub H} measured from 10{sup 24} to 10{sup 26} cm{sup −2}, and a wide range of covering factors, where individual measurements range from 0.2 to 0.9. We find that the covering factor, f{sub c}, is a strongly decreasing function of the intrinsic 2–10 keV luminosity, L{sub X}, where f{sub c} = (−0.41 ± 0.13)log{sub 10}(L{sub X}/erg s{sup −1})+18.31 ± 5.33, across more than two orders of magnitude in L{sub X} (10{sup 41.5}–10{sup 44} erg s{sup −1}). The covering factors measured here agree well with the obscured fraction as a function of L{sub X} as determined by studies of local AGNs with L{sub X} > 10{sup 42.5} erg s{sup −1}.« less

Determining the Covering Factor of Compton-Thick Active Galactic Nuclei with NuSTAR

NASA Technical Reports Server (NTRS)

Brightman, M.; Balokovic, M.; Stern, D.; Arevalo, P.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Zhang, W. W.

2015-01-01

The covering factor of Compton-thick (CT) obscuring material associated with the torus in active galactic nuclei (AGNs) is at present best understood through the fraction of sources exhibiting CT absorption along the line of sight (N(sub H) greater than 1.5 x 10(exp 24) cm(exp -2)) in the X-ray band, which reveals the average covering factor. Determining this CT fraction is difficult, however, due to the extreme obscuration. With its spectral coverage at hard X-rays (greater than 10 keV), Nuclear Spectroscopic Telescope Array (NuSTAR) is sensitive to the AGNs covering factor since Compton scattering of X-rays off optically thick material dominates at these energies. We present a spectral analysis of 10 AGNs observed with NuSTAR where the obscuring medium is optically thick to Compton scattering, so-called CT AGNs. We use the torus models of Brightman and Nandra that predict the X-ray spectrum from reprocessing in a torus and include the torus opening angle as a free parameter and aim to determine the covering factor of the CT gas in these sources individually. Across the sample we find mild to heavy CT columns, with N(sub H) measured from 10(exp 24) to 10(exp 26) cm(exp -2), and a wide range of covering factors, where individual measurements range from 0.2 to 0.9. We find that the covering factor, f(sub c), is a strongly decreasing function of the intrinsic 2-10 keV luminosity, L(sub X), where f(sub c) = (-0.41 +/- 0.13)log(sub 10)(L(sub X)/erg s(exp -1))+18.31 +/- 5.33, across more than two orders of magnitude in L(sub X) (10(exp 41.5) - 10(exp 44) erg s(exp -1)). The covering factors measured here agree well with the obscured fraction as a function of LX as determined by studies of local AGNs with L(sub X) greater than 10(exp 42.5) erg s(exp -1).

Driving the bumpy road to commercialization.

PubMed

Parenteau, Nancy L

2014-06-01

Tissue engineering has always had an applied focus and there is hardly an academic publication that does not mention the applicability of its findings to the future development of a medical product. I have been involved in the industry side of tissue engineering from the start, pursuing a variety of applications, some making it to the marketplace. There have been many lessons that I have learned from direct experience (mistakes and successes), observation, through advising others, and now, in developing innovative ways to identify and eliminate the regenerative cell populations within a tumor. This brief overview of some of these lessons is written with the next generation of pioneering product developers in mind: the biologists, biochemists, and engineers who will dedicate their careers to driving medical and commercial progress in tissue engineering.

[Symbolical violence in the access of disabled persons to basic health units].

PubMed

de França, Inacia Sátiro Xavier; Pagliuca, Lorita Marlena Freitag; Baptista, Rosilene Santos; de França, Eurípedes Gil; Coura, Alexsandro Silva; de Souza, Jeová Alves

2010-01-01

A descriptive study which aimed to characterize the conditions of people with disabilities (PD) in the Basic Health Units-UBS. Data were collected in January 2009 in 20 UBSF. It was used digital camera and check list based on the 9050-NBR ABNT. The results showed: Access town - no traffic lights (100%) of lanes for pedestrians (100%), bumpy sidewalks (90%); Access in UBS: non-standard ports (30%) staircases without banisters (20%); floor outside the standard (75%), in disagreement with standard mobile (20%), drinking at odds with standard (55%), making it difficult to people with disabilities to use a filter (30%), has no drinking or filters (15%); telephones installed inadequately (55%); inaccessible restrooms (96%). Access to UBS of PD is permeated by the symbolic violence.

Spirit Beholds Bumpy Boulder

NASA Technical Reports Server (NTRS)

2006-01-01

As NASA's Mars Exploration Rover Spirit began collecting images for a 360-degree panorama of new terrain, the rover captured this view of a dark boulder with an interesting surface texture. The boulder sits about 40 centimeters (16 inches) tall on Martian sand about 5 meters (16 feet) away from Spirit. It is one of many dark, volcanic rock fragments -- many pocked with rounded holes called vesicles -- littering the slope of 'Low Ridge.' The rock surface facing the rover is similar in appearance to the surface texture on the outside of lava flows on Earth.

Spirit took this approximately true-color image with the panoramic camera on the rover's 810th sol, or Martian day, of exploring Mars (April 13, 2006), using the camera's 753-nanometer, 535-nanometer, and 432-nanometer filters.

Extreme coronagraphy with an adaptive hologram. Simulations of exo-planet imaging

NASA Astrophysics Data System (ADS)

Ricci, D.; Le Coroller, H.; Labeyrie, A.

2009-08-01

Aims: We present a solution to improve the performance of coronagraphs for the detection of exo-planets. Methods: We simulate numerically several kinds of coronagraphic systems, with the aim of evaluating the gain obtained with an adaptive hologram. Results: The detection limit in flux ratio between a star and a planet (F_s/F_p) observed with an apodized Lyot coronagraph characterized by wavefront bumpiness imperfections of λ/20 (resp. λ/100) turns out to be increased by a factor of 103.4 (resp. 105.1) when equipped with a hologram. Conclusions: This technique could provide direct imaging of an exo-Earth at a distance of 11 parsec with a 6.5 m space telescope such as the JWST with the optical quality of the HST.

Prospects for measuring the fuel ion ratio in burning ITER plasmas using a DT neutron emission spectrometer

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

Hellesen, C.; Skiba, M., E-mail: mateusz.skiba@physics.uu.se; Dzysiuk, N.

2014-11-15

The fuel ion ratio n{sub t}/n{sub d} is an essential parameter for plasma control in fusion reactor relevant applications, since maximum fusion power is attained when equal amounts of tritium (T) and deuterium (D) are present in the plasma, i.e., n{sub t}/n{sub d} = 1.0. For neutral beam heated plasmas, this parameter can be measured using a single neutron spectrometer, as has been shown for tritium concentrations up to 90%, using data obtained with the MPR (Magnetic Proton Recoil) spectrometer during a DT experimental campaign at the Joint European Torus in 1997. In this paper, we evaluate the demands thatmore » a DT spectrometer has to fulfill to be able to determine n{sub t}/n{sub d} with a relative error below 20%, as is required for such measurements at ITER. The assessment shows that a back-scattering time-of-flight design is a promising concept for spectroscopy of 14 MeV DT emission neutrons.« less

Differential interferometry for measurement of density fluctuations and fluctuation-induced transport (invited)

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

Lin, L.; Ding, W. X.; Brower, D. L.

2010-10-15

Differential interferometry employs two parallel laser beams with a small spatial offset (less than beam width) and frequency difference (1-2 MHz) using common optics and a single mixer for a heterodyne detection. The differential approach allows measurement of the electron density gradient, its fluctuations, as well as the equilibrium density distribution. This novel interferometry technique is immune to fringe skip errors and is particularly useful in harsh plasma environments. Accurate calibration of the beam spatial offset, accomplished by use of a rotating dielectric wedge, is required to enable broad application of this approach. Differential interferometry has been successfully used onmore » the Madison Symmetric Torus reversed-field pinch plasma to directly measure fluctuation-induced transport along with equilibrium density profile evolution during pellet injection. In addition, by combining differential and conventional interferometry, both linear and nonlinear terms of the electron density fluctuation energy equation can be determined, thereby allowing quantitative investigation of the origin of the density fluctuations. The concept, calibration, and application of differential interferometry are presented.« less

US fusion effort hit by tokamak losses

NASA Astrophysics Data System (ADS)

Gwynne, Peter

2016-11-01

Stewart Prager, director of the Princeton Plasma Physics Laboratory (PPPL) in the US, resigned in late September just weeks after a major setback at the lab's National Spherical Torus Experiment Upgrade (NSTX-U).

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.; Hester, J. Jeff; Tennant, Allyn F.; Elsner, Ronald F.; Schulz, Norbert S.; Marshall, Herman L.; Karovska, Margarita; Nichols, Joy S.; Swartz, Douglas A.; Kolodziejczak, Jeffery J.

2000-01-01

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced Charge Coupled Devices (CCD) Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

Confinement time of electron plasma approaching magnetic pumping transport limit in small aspect ratio C-shaped torus

NASA Astrophysics Data System (ADS)

Lachhvani, Lavkesh; Pahari, Sambaran; Goswami, Rajiv; Bajpai, Manu; Yeole, Yogesh; Chattopadhyay, P. K.

2016-06-01

A long confinement time of electron plasma, approaching magnetic pumping transport limit, has been observed in SMARTEX-C (a small aspect ratio partial torus with R o / a ˜ 1.59 ). Investigations of the growth rate reveal that they are governed by instabilities like resistive wall destabilization, ion driven instabilities, and electron-neutral collisions. Successful confinement of electron plasmas exceeding > 1 × 10 5 poloidal E → × B → rotations lasting for nearly 2.1 ± 0.1 s is achieved by suppressing these instabilities. The confinement time has been estimated in two ways: (a) from the frequency scaling of the linear diocotron mode launched from sections of the wall that are also used as capacitive probes and (b) by dumping the plasma onto a charge collector at different hold times.

Trial wave functions for a composite Fermi liquid on a torus

NASA Astrophysics Data System (ADS)

Fremling, M.; Moran, N.; Slingerland, J. K.; Simon, S. H.

2018-01-01

We study the two-dimensional electron gas in a magnetic field at filling fraction ν =1/2 . At this filling the system is in a gapless state which can be interpreted as a Fermi liquid of composite fermions. We construct trial wave functions for the system on a torus, based on this idea, and numerically compare these to exact wave functions for small systems found by exact diagonalization. We find that the trial wave functions give an excellent description of the ground state of the system, as well as its charged excitations, in all momentum sectors. We analyze the dispersion of the composite fermions and the Berry phase associated with dragging a single fermion around the Fermi surface and comment on the implications of our results for the current debate on whether composite fermions are Dirac fermions.

Multi-Point Thomson Scattering Diagnostic for the Helicity Injected Torus

NASA Astrophysics Data System (ADS)

Liptac, J. E.; Smith, R. J.; Hoffman, C. S.; Jarboe, T. R.; Nelson, B. A.; Leblanc, B. P.; Phillips, P.

1999-11-01

The multi-point Thomson scattering system on the Helicity Injected Torus--II can determine electron temperature and density at 11 radial positions at a single time during the plasma discharge. The system includes components on loan from both PPPL and from the University of Texas. The collection optics and Littrow spectrometer from Princeton, and the 1 GW laser and multi-anode microchannel plate detector from Texas have been integrated into a compact structure, creating a mobile and reliable diagnostic. The mobility of the system allows alignment to occur in a room adjacent to the experiment, greatly reducing the disturbance to normal machine operation. The four main parts of the Thomson scattering system, namely, the laser, the beam line, the collection optics, and the mobile structure are presented and discussed.

Discovery of Spatial and Spectral Structure in the X-Ray Emission from the Crab Nebula.

PubMed

Weisskopf; Hester; Tennant; Elsner; Schulz; Marshall; Karovska; Nichols; Swartz; Kolodziejczak; O'Dell

2000-06-20

The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula.

Equilibrium location for spherical DNA and toroidal cyclodextrin

NASA Astrophysics Data System (ADS)

Sarapat, Pakhapoom; Baowan, Duangkamon; Hill, James M.

2018-05-01

Cyclodextrin comprises a ring structure composed of glucose molecules with an ability to form complexes of certain substances within its central cavity. The compound can be utilised for various applications including food, textiles, cosmetics, pharmaceutics, and gene delivery. In gene transfer, the possibility of forming complexes depends upon the interaction energy between cyclodextrin and DNA molecules which here are modelled as a torus and a sphere, respectively. Our proposed model is derived using the continuum approximation together with the Lennard-Jones potential, and the total interaction energy is obtained by integrating over both the spherical and toroidal surfaces. The results suggest that the DNA prefers to be symmetrically situated about 1.2 Å above the centre of the cyclodextrin to minimise its energy. Furthermore, an optimal configuration can be determined for any given size of torus and sphere.

Mind-to-mind heteroclinic coordination: Model of sequential episodic memory initiation.

PubMed

Afraimovich, V S; Zaks, M A; Rabinovich, M I

2018-05-01

Retrieval of episodic memory is a dynamical process in the large scale brain networks. In social groups, the neural patterns, associated with specific events directly experienced by single members, are encoded, recalled, and shared by all participants. Here, we construct and study the dynamical model for the formation and maintaining of episodic memory in small ensembles of interacting minds. We prove that the unconventional dynamical attractor of this process-the nonsmooth heteroclinic torus-is structurally stable within the Lotka-Volterra-like sets of equations. Dynamics on this torus combines the absence of chaos with asymptotic instability of every separate trajectory; its adequate quantitative characteristics are length-related Lyapunov exponents. Variation of the coupling strength between the participants results in different types of sequential switching between metastable states; we interpret them as stages in formation and modification of the episodic memory.

Entanglement on linked boundaries in Chern-Simons theory with generic gauge groups

NASA Astrophysics Data System (ADS)

Dwivedi, Siddharth; Singh, Vivek Kumar; Dhara, Saswati; Ramadevi, P.; Zhou, Yang; Joshi, Lata Kh

2018-02-01

We study the entanglement for a state on linked torus boundaries in 3 d Chern-Simons theory with a generic gauge group and present the asymptotic bounds of Rényi entropy at two different limits: (i) large Chern-Simons coupling k, and (ii) large rank r of the gauge group. These results show that the Rényi entropies cannot diverge faster than ln k and ln r, respectively. We focus on torus links T (2 , 2 n) with topological linking number n. The Rényi entropy for these links shows a periodic structure in n and vanishes whenever n = 0 (mod p), where the integer p is a function of coupling k and rank r. We highlight that the refined Chern-Simons link invariants can remove such a periodic structure in n.

Manufacturing Challenges and Benefits When Scaling the HIAD Stacked-Torus Aeroshell to a 15m-Class System

NASA Technical Reports Server (NTRS)

Swanson, Greg; Cheatwood, Neil; Johnson, Keith; Calomino, Anthony; Hughes, Steve; Gilles, Brian; Anderson, Paul; Bond, Bruce

2016-01-01

Over a decade of work has been conducted in the development of NASAs Hypersonic Inflatable Aerodynamic Decelerator (HIAD) deployable aeroshell technology. This effort has included multiple ground test campaigns and flight tests culminating in the HIAD projects second generation (Gen-2) aeroshell system. The HIAD project team has developed, fabricated, and tested stacked-torus inflatable structures (IS) with flexible thermal protection systems (F-TPS) ranging in diameters from 3-6m, with cone angles of 60 and 70 deg. To meet NASA and commercial near term objectives, the HIAD team must scale the current technology up to 12-15m in diameter. The HIAD projects experience in scaling the technology has reached a critical juncture in development. Growing from a 6m to a 15m class system will introduce many...

Lyman-alpha observations in the vicinity of Saturn with Copernicus

NASA Technical Reports Server (NTRS)

Barker, E.; Cazes, S.; Emerich, C.; Vidal-Madjar, A.; Owen, T.

1980-01-01

For the first time, high-resolution Ly-alpha observations of the Saturn vicinity were completed with the Princeton spectrometer on board the Copernicus satellite. They showed that near a minimum solar activity the emissions related to several sources are 250 + or - 50 rayleighs for the interplanetary medium in a near-downwind direction, less than 100 rayleighs for the rings, 200 + or - 100 rayleighs for a torus linked to the Titan orbit, and 1400 + or - 450 rayleighs for the disk of Saturn. These results induce some constraints through the corresponding theoretical evaluations: the B ring as the primary source of the atoms for the ring emissions; an efficient production mechanism for hydrogen atoms in the Titan torus; and a slightly larger eddy diffusion coefficient in the Saturn atmosphere than in the Jupiter atmosphere near solar minimum.

The equilibrium of atmospheric sodium. [in atmospheres of Earth, Io, Mercury and Moon

NASA Technical Reports Server (NTRS)

Hunten, Donald M.

1992-01-01

We now have four examples of planetary objects with detectable sodium (and potassium) in their atmospheres: Earth, Io, Mercury and the moon. After a summary of the observational data, this survey discusses proposed sources and sinks. It appears that Io's surface material is rich in frozen SO2, but with around 1 percent of some sodium compound. The Io plasma torus contains ions of S, O and Na, also with at least one molecular ion containing Na. In turn, impact by these ions probably sustains the torus, as well as an extended neutral corona. A primary source for the Earth, Mercury and the moon is meteoroidal bombardment; at Mercury and perhaps the moon it may be supplemented by degassing of atoms from the regolith. Photoionization is important everywhere, although hot electrons are dominant at Io.

Reduction of plasma density in the Helicity Injected Torus with Steady Inductance experiment by using a helicon pre-ionization source

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

Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S.

2013-10-15

A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10{sup 19} m{sup −3} to 1 × 10{sup 19} m{sup −3}. Deuterium spheromak formation is possible with density as low as 2 × 10{sup 18} m{sup −3}. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reductionmore » of breakdown density is presented.« less

Charged particle modification of ices in the Saturnian and Jovian systems

NASA Technical Reports Server (NTRS)

Johnson, R. E.; Barton, L. A.; Boring, J. W.; Jesser, W. A.; Brown, W. L.

1985-01-01

The modification by ion bombardment of the surfaces of icy objects in the Saturnian and Jovian systems is discussed. Chemical changes in ices are induced by breaking of bonds and by implantation of incident ions. Long-term irradiation by fast ions produces physical changes such as increasing the surface reflectivity and ability to scatter light. On large satellites, molecules which are ejected by ion bombardment are redistributed across the surfaces of large satellites. For small satellites and ring particles bombarded by ions, such as those of Saturn, most or all of the sputtered material is lost to space, forming a neutral torus in the locale of the satellite orbits and rings and supplying ions to the magnetosphere. Noting the existence of such a torus, the sputter erosion and possible stabilization of the E-ring of Saturn is discussed.

New families of interpolating type IIB backgrounds

NASA Astrophysics Data System (ADS)

Minasian, Ruben; Petrini, Michela; Zaffaroni, Alberto

2010-04-01

We construct new families of interpolating two-parameter solutions of type IIB supergravity. These correspond to D3-D5 systems on non-compact six-dimensional manifolds which are mathbb{T}2 fibrations over Eguchi-Hanson and multi-center Taub-NUT spaces, respectively. One end of the interpolation corresponds to a solution with only D5 branes and vanishing NS three-form flux. A topology changing transition occurs at the other end, where the internal space becomes a direct product of the four-dimensional surface and the two-torus and the complexified NS-RR three-form flux becomes imaginary self-dual. Depending on the choice of the connections on the torus fibre, the interpolating family has either mathcal{N}=2 or mathcal{N}=1 supersymmetry. In the mathcal{N}=2 case it can be shown that the solutions are regular.

Extreme ultraviolet observations from Voyager 1 encounter with Jupiter

NASA Technical Reports Server (NTRS)

Broadfoot, A. L.; Belton, M. J. S.; Takacs, P. Z.; Sandel, B. R.; Shemansky, D. E.; Holberg, J. B.; Ajello, J. M.; Atreya, S. K.; Donahue, T. M.; Moos, H. W.

1979-01-01

Observations of the optical extreme ultraviolet spectrum of the Jupiter planetary system during the Voyager 1 encounter have revealed previously undetected physical processes of significant proportions. Bright emission lines of S(+2), S(+3), O(+2) indicating an electron temperature of 100,000 K have been identified in preliminary analyses of the Io plasma torus spectrum. Strong auroral atomic and molecular hydrogen emissions have been observed in the polar regions of Jupiter near magnetic field lines that map the torus into the atmosphere of Jupiter. The observed resonance scattering of solar hydrogen Lyman alpha by the atmosphere of Jupiter and the solar occultation experiment suggest a hot thermosphere (greater than or equal to 1000 K) with a large atomic hydrogen abundance. A stellar occultation by Ganymede indicates that its atmosphere is at most an exosphere.

Mission Applications of a HIAD for the Mars Southern Highlands

NASA Technical Reports Server (NTRS)

Winski, Richard; Bose, Dave; Komar, David R.; Samareh, Jamshid

2013-01-01

Recent discoveries of evidence of a flowing liquid in craters throughout the Mars Southern Highlands, like Terra Sirenum, have spurred interest in sending science missions to those locations; however, these locations are at elevations that are much higher (0 to +4 km MOLA) than any previous landing site (-1 to -4 km MOLA). New technologies may be needed to achieve a landing at these sites with significant payload mass to the surface. A promising technology is the hypersonic inflatable aerodynamic decelerator (HIAD); a number of designs have been advanced but the stacked torus has been recently successfully flight tested in the IRVE-2 and IRVE-3 projects through the NASA Langley Research Center. This paper will focus on a variety of mission applications of the stacked torus type attached HIAD to the Mars southern highlands.

Dynamics of knotted flexible loops settling under a constant force in a viscous fluid

NASA Astrophysics Data System (ADS)

Gruziel, Magdalena; Thyagarajan, Krishnan; Dietler, Giovanni; Szymczak, Piotr; Ekiel-Jezewska, Maria

2017-11-01

Sedimenting chains of metal beads knotted to a topology of a torus knot tend to stabilize in the form of extended, flat, tightly interwound loops. In this configuration they perform an oscillatory motion of the loops swirling periodically around each other. Stokesian dynamics simulations of elastic fibers confirm the long-lasting character of the traveling wave-like swirling motion and show also the accompanying rotation of the system. Moreover, the periodic motion shows striking resemblance to the stable solutions for the evolution of vortices of torus knot topology. Using the results of the simulations we study the dependence of the frequencies and sedimentation velocities on the length of the fiber. We also notice the dependence of the knot dynamics on the bending stiffness of the fiber and the knot rank. NCN-2015/19/D/ST8/03199.

In situ observations of dust particles in Martian dust belts using a large-sensitive-area dust sensor

NASA Astrophysics Data System (ADS)

Kobayashi, Masanori; Krüger, Harald; Senshu, Hiroki; Wada, Koji; Okudaira, Osamu; Sasaki, Sho; Kimura, Hiroshi

2018-07-01

In order to determine whether Martian dust belts (ring or torus) actually exist and, if so, to determine the characteristics of the dust, we propose a Circum-Martian Dust Monitor (CMDM) to be deployed on the Martian Moons Exploration (MMX) project, in which JAXA plans to launch the spacecraft in 2024, investigate Phobos and Deimos, and return samples back to Earth. The CMDM is a newly developed instrument that is an impact dust detector. It weighs only 650 g and has a sensor aperture area of ∼1 m2, according to the conceptual design study. Detectable velocities (v) range from 0.5 km/s to more than 70 km/s, which will cover all possible dust particles: circummartian (low v), interplanetary (mid v), and interstellar (high v) particles. The measurable mass ranges from 1.3 × 10-9 g to 7.8 × 10-7 g at v = 0.5 km/s. Since the MMX spacecraft will take a quasi-circular, prograde orbit around Mars, the CMDM will be able to investigate particles from Phobos and Deimos with relative velocities lower than 1 km/s. Therefore, the CMDM will be able to determine whether or not a confined dust ring exists along Phobos' orbit and whether an extended dust torus exists along Deimos' orbit. It may also be able to clarify whether or not any such ring or torus are self-sustained.

Numerical calculation of the neoclassical electron distribution function in an axisymmetric torus

NASA Astrophysics Data System (ADS)

Lyons, B. C.; Jardin, S. C.; Ramos, J. J.

2011-10-01

We solve for a stationary, axisymmetric electron distribution function (fe) in a torus using a drift-kinetic equation (DKE) with complete Landau collision operator. All terms are kept to gyroradius and collisionality orders relevant to high- temperature tokamaks (i.e., the neoclassical banana regime for electrons). A solubility condition on the DKE determines the non-Maxwellian pieces of fe (called fNMe) to all relevant orders. We work in a 4D phase space (ψ , θ , v , λ) , where ψ defines a flux surface, θ is the poloidal angle, v is the total velocity, and λ is the pitch angle parameter. We expand fNMe in finite elements in both v and λ. The Rosenbluth potentials, Φ and Ψ, which define the collision operator, are expanded in Legendre series in cos χ , where χ is the pitch angle, Fourier series in cos θ , and finite elements in v. At each ψ, we solve a block tridiagonal system for fNMe, Φ, and Ψ simultaneously, resulting in a neoclassical fe for the entire torus. Our goal is to demonstrate that such a formulation can be accurately and efficiently solved numerically. Results will be compared to other codes (e.g., NCLASS, NEO) and could be used as a kinetic closure for an MHD code (e.g., M3D-C1). Supported by the DOE SCGF and DOE Contract # DE-AC02-09CH11466. Based on analytic work by Ramos, PoP 17, 082502 (2010).

Remote sensing of the Io torus plasma ribbon using natural radio occultation of the Jovian radio emissions

NASA Astrophysics Data System (ADS)

Boudjada, M. Y.; Galopeau, P. H. M.; Sawas, S.; Lammer, H.

2014-09-01

We study the Jovian hectometric (HOM) emissions recorded by the RPWS (Radio and Plasma Wave Science) experiment onboard the Cassini spacecraft during its Jupiter flyby. We analyze the attenuation band associated with the intensity extinction of HOM radiation. This phenomenon is interpreted as a refraction effect of the Jovian hectometric emission inside the Io plasma torus. This attenuation band was regularly observed during periods of more than 5 months, from the beginning of October 2000 to the end of March 2001. We estimate for this period the variation of the electron density versus the central meridian longitude (CML). We find a clear local time dependence. Hence the electron density was not higher than 5.0 × 104 cm-3 during 2 months, when the spacecraft approached the planet on the dayside. In the late afternoon and evening sectors, the electron density increases to 1.5 × 105 cm-3 and reach a higher value at some specific occasions. Additionally, we show that ultraviolet and hectometric wavelength observations have common features related to the morphology of the Io plasma torus. The maxima of enhancements/attenuations of UV/HOM observations occur close to the longitudes of the tip of the magnetic dipole in the southern hemisphere (20° CML) and in the northern hemisphere (200° CML), respectively. This is a significant indication about the importance of the Jovian magnetic field as a physical parameter in the coupling process between Jupiter and the Io satellite.

ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-Velocity Bipolar Jets and an Expanding Torus

PubMed Central

Sahai, R.; Vlemmings, W.H.T.; Gledhill, T.; Sánchez Contreras, C.; Lagadec, E.; Nyman, L-Å; Quintana-Lacaci, G.

2017-01-01

We have mapped 12CO J=3–2 and other molecular lines from the “water-fountain” bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ∼0⋅″35 resolution using ALMA. We find (i) two very high-speed knotty, jet-like molecular outflows, (ii) a central high-density (> few × 106 cm−3), expanding torus of diameter 1300 AU, and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5 × 10−4 M⊙ yr−1 in the past ~455 yr. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally-emitting dust, implies a substantial mass (0.017 M⊙) of very large (~mm-sized) grains. The measured expansion ages of the above structural components imply that the torus (age~160 yr) and the younger high-velocity outflow (age~110 yr) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi-Hoyle-Lyttleton wind accretion and wind Roche lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common envelope evolution are needed. PMID:28191303

ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-Velocity Bipolar Jets and an Expanding Torus.

PubMed

Sahai, R; Vlemmings, W H T; Gledhill, T; Sánchez Contreras, C; Lagadec, E; Nyman, L-Å; Quintana-Lacaci, G

2017-01-20

We have mapped 12 CO J=3-2 and other molecular lines from the "water-fountain" bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with [Formula: see text] resolution using ALMA. We find (i) two very high-speed knotty, jet-like molecular outflows, (ii) a central high-density (> few × 10 6 cm -3 ), expanding torus of diameter 1300 AU, and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5 × 10 -4 M ⊙ yr -1 in the past ~455 yr. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally-emitting dust, implies a substantial mass (0.017 M ⊙ ) of very large (~mm-sized) grains. The measured expansion ages of the above structural components imply that the torus (age~160 yr) and the younger high-velocity outflow (age~110 yr) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi-Hoyle-Lyttleton wind accretion and wind Roche lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common envelope evolution are needed.

Recent Progress on Spherical Torus Research

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

Ono, Masayuki; Kaita, Robert

2014-01-01

The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configurationmore » can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.« less

The Helicity Injected Torus (HIT) Program

NASA Astrophysics Data System (ADS)

Jarboe, T. R.; Gu, P.; Hamp, W.; Izzo, V.; Jewell, P.; Liptac, J.; McCollam, K. J.; Nelson, B. A.; Raman, R.; Redd, A. J.; Shumlak, U.; Sieck, P. E.; Smith, R. J.; Jain, K. K.; Nagata, M.; Uyama, T.

2000-10-01

The purpose of the Helicity Injected Torus (HIT) program is to develop current drive techniques for low-aspect-ratio toroidal plasmas. The present HIT-II spherical tokamak experiment is capable of both Coaxial Helicity Injection (CHI) and transformer action current drive. The HIT-II device itself is modestly sized (major radius R = 0.3 m, minor radius a = 0.2 m, with an on-axis magnetic field of up to Bo = 0.5 T), but has demonstrated toroidal plasma currents of up to 200 kA, using either CHI or transformer drive. An overview of ongoing research on HIT-II plasmas, including recent results, will be presented. An electron-locking model has been developed for helicity injection current drive; a description of this model will be presented, as well as comparisons to experimental results from the HIT and HIT-II devices. Empirical results from both the HIT program and past spheromak research, buttressed by theoretical developments, have led to the design of the upcoming HIT-SI (Helicity Injected Torus with Steady Inductive helicity injection) device (T.R. Jarboe, Fusion Technology 36, p. 85, 1999). HIT-SI will be able to form a high-beta spheromak, a low aspect ratio RFP or a spherical tokamak using constant inductive helicity injection. The HIT-SI design and construction progress will be presented.

Compact Torus Acceleration and Injection Experiment

NASA Astrophysics Data System (ADS)

Fukumoto, Naoyuki; Fujiwara, Makoto; Nagata, Masayoshi; Uyama, Tadao; Oda, Yasushi; Azuma, Kingo

1996-11-01

The spheromak-type compact torus (CT) acceleration and injection experiment has been carried out using the Himeji Institute of Technology Compact Torus Injector (HIT-CTI). We explore the possibility of refueling, density control, current drive, and edge electric field control of tokamak plasma by means of CT injection. In last September the new HIT-CTI was built up to achieve higher speed (Vct>200 km/s) and higher density CT plasmoid by improving the capacitor bank system and eliminating the impurity and neutral particles. At initial formation discharge tests the gun for formation and compression successfully produced a CT plasmoid and injected it between electrodes for acceleration. (Initial velocity Vct.ini. 32 km/s, Bct 1 kG, Rct=5.5 cm). The formation capacitor bank will be upgraded to two 36 mF capacitors operating at 20 kV (14.4 kJ). The acceleration capacitor bank will be also upgraded to two 36 mF capacitors operating at 20 kV (14.4 kJ). The HIT-CTI will be optimized to obtain suitable CT parameters after acceleration (Bct>5 kG, Lct 20 cm, Vct>200 km/s). In the respect of CT parameter measurement magnetic probes and a He-Ne laser interferometer will be employed in order to measure the CT magnetic field, velocity, density, and length. CT acceleration experimental data on the HIT-CTI and the plan of CT injection experiment on the JFT-2M tokamak (JAERI) will be presented at the meeting.

Compact Torus Injection Experiments on the H.I.T. teststand and the JFT-2M tokamak

NASA Astrophysics Data System (ADS)

Fukumoto, Naoyuki; Fujiwara, Makoto; Kuramoto, Keiji; Ageishi, Masaya; Nagata, Masayoshi; Uyama, Tadao; Ogawa, Hiroaki; Kasai, Satoshi; Hasegawa, Kouichi; Shibata, Takatoshi

1997-11-01

A spheromak-type compact torus (CT) acceleration and injection experiment has been carried out using the Himeji Institute of Technology Compact Torus Injector (HIT-CTI). We investigate the possibility of refueling, density control, current drive, and edge electric field control of tokamak plasmas by means of CT injection. The HIT-CTI produces a CT with a speed of 200 km/s and a density of 1× 10^21m-3. We have constructed new electrodes and power supplies, and will install the HIT-CTI on the JFT-2M tokamak at JAERI in Autumn 1997. The outer electrode serves as a common ground for both the formation bank (144μF, 20kV) and the acceleration bank (92.4μF, 40kV). If the external toroidal field of the tokamak is applied across the CT acceleration region, the CT kinetic energy might decrease during penetration into the field lines joining the inner and outer electrode. This could result in the CT not being able to reach the core of the tokamak plasma. Determining the optimum position of the inner electrode is one of the near term goals of this research. We will present magnetic probe, He-Ne interferometer and fast framing camera data from experiments at H.I.T., where a CT was accelerated into a transverse field. We will also present initial results from the operation of the HIT-CTI on the JFT-2M tokamak.

Development of rotating magnetic field coil system in the HIST spherical torus device

NASA Astrophysics Data System (ADS)

Yoshikawa, T.; Kikuchi, Y.; Yamada, S.; Hashimoto, S.; Nishioka, T.; Fukumoto, N.; Nagata, M.

2007-11-01

Coaxial Helicity Injection (CHI) is one of most attractive methods to achieve non-inductive current drive in spherical torus devices. The current drive mechanism of CHI relies on MHD relaxation process of rotating kink behavior [1], so that there is a possibility to control the CHI by using an externally applied rotating magnetic field (RMF). We have recently started to develop a RMF coil system in the HIST spherical torus device. Eight coils are located above and below the midplane at four toroidal locations so that the RMF is resonant with n = 1 rotating kink mode driven by the CHI. In addition, the RMF coil set is installed inside a flux conserver of 5 mm thickness (cut-off frequency ˜ 170 Hz) so that the RMF penetrates into the plasma. The coil winding is made of 20 turns of enameled copper circular wires (1.5 mm^2 conductor cross section), covered with a thin stainless steal case of 0.5 mm thickness (cut-off frequency ˜ 710 kHz). The RMF system is driven by an IGBT inverter power supply (nominal current: 1 kA, nominal voltage: 1 kV) with an operating frequency band from 10 kHz to 30 kHz. The estimated amplitude of RMF neglecting effects of image current at the flux conserver is a few tens Gauss at around the magnetic axis. A preliminary experimental result will be shown in the conference. [1] M. Nagata, et al., Physics of Plasmas 10, 2932 (2003).

ALMA Observations of the Water Fountain Pre-planetary Nebula IRAS 16342-3814: High-velocity Bipolar Jets and an Expanding Torus

NASA Astrophysics Data System (ADS)

Sahai, R.; Vlemmings, W. H. T.; Gledhill, T.; Sánchez Contreras, C.; Lagadec, E.; Nyman, L.-Å; Quintana-Lacaci, G.

2017-01-01

We have mapped 12CO J = 3-2 and other molecular lines from the “water fountain” bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ˜0.″35 resolution using Atacama Large Millimeter/submillimeter Array. We find (I) two very high-speed knotty, jet-like molecular outflows; (II) a central high-density (> {few}× {10}6 cm-3), expanding torus of diameter 1300 au; and (III) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to > 3.5× {10}-4 M⊙ yr-1 in the past ˜455 years. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally emitting dust, implies a substantial mass (0.017 M⊙) of very large (˜millimeter-sized) grains. The measured expansion ages of the above structural components imply that the torus (age ˜160 years) and the younger high-velocity outflow (age ˜110 years) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi-Hoyle-Lyttleton wind accretion and wind Roche-lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common-envelope evolution are needed.

Supercritical Fluid Chromatography with Photodiode Array Detection in the Determination of Fat-Soluble Vitamins in Hemp Seed Oil and Waste Fish Oil.

PubMed

Tyśkiewicz, Katarzyna; Gieysztor, Roman; Maziarczyk, Izabela; Hodurek, Paweł; Rój, Edward; Skalicka-Woźniak, Krystyna

2018-05-10

In the presented study for the first time a new, optimized, fast SFC (supercritical fluid chromatography) method was applied to separate in one run fat-soluble vitamins from waste fish oil, including cis -and tran s-retinyl palmitate, cis - and trans -retinyl acetate, retinol, α-tocopherol, β-tocopherol, γ‑tocopherol, δ-tocopherol, ergocalciferol (D₂), cholecalciferol (D₃), cis - and trans -phylloquinone (K₁) and menaquinone-4 (K₂-MK4). Vitamins were baseline separated on an Acquity UPC² (ultra performance convergence chromatography) HSS C18 SB (highly strength chemically modified silica) column within 13 min. The influence of the stationary phase, such as Torus 1-AA (1-aminoanthracene), Torus Diol (high density diol), Torus DEA (diethylamine), BEH (silica with no bonding), BEH-2EP (2-ethylpirydine), CSH Fluoro-Phenyl (silica with fluoro-phenyl groups), column temperature, flow rate and back pressure on the separation of the compounds was described. The application of the modified saponification procedure allowed us to increase concentration in the sample prepared for the analysis of γ‑tocopherol from less than 1% (wt %) to 14% for the first time. In addition, α‑tocopherol, γ‑tocopherol, δ‑tocopherol and retinol were identified in waste fish oil. Vitamin purification and analysis in waste fish oil are reported for the first time here. Due to the short time and effectiveness of the proposed method, it can be easily applied in industrial processes.

Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

DOE PAGES

Ghoshal, P. K.; Pastor, O.; Kashy, D.; ...

2014-12-18

The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coilmore » case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.« less

Radial Variations in the Io Plasma Torus during the Cassini Era

NASA Technical Reports Server (NTRS)

Delamere, P. A.; Bagenal, F.; Steffl, A.

2005-01-01

A radial scan through the midnight sector of the Io plasma torus was made by the Cassini Ultraviolet Imaging Spectrograph on 14 January 2001, shortly after closest approach to Jupiter. From these data, Steffl et al. (2004a) derived electron temperature, plasma composition (ion mixing ratios), and electron column density as a function of radius from L = 6 to 0 as well as the total luminosity. We have advanced our homogeneous model of torus physical chemistry (Delamere and Bagenal, 2003) to include latitudinal and radial variations in a manner similar to the two-dimensional model by Schreier et al. (1998). The model variables include: (1) neutral source rate, (2) radial transport coefficient, (3) the hot electron fraction, (4) hot electron temperature, and (5) the neutral O/S ratio. The radial variation of parameters 1-4 are described by simple power laws, making a total of nine parameters. We have explored the sensitivity of the model results to variations in these parameters and compared the best fit with previous Voyager era models (schreier et al., 1998), galileo data (Crary et al., 1998), and Cassini observations (steffl et al., 2004a). We find that radial variations during the Cassini era are consistent with a neutral source rate of 700-1200 kg/s, an integrated transport time from L = 6 to 9 of 100-200 days, and that the core electron temperature is largely determined by a spatially and temporally varying superthermal electron population.

New insights into the mechanisms of water-stress-induced cavitation in conifers.

PubMed

Cochard, Hervé; Hölttä, Teemu; Herbette, Stéphane; Delzon, Sylvain; Mencuccini, Maurizio

2009-10-01

Cavitation resistance is a key parameter to understand tree drought tolerance but little is known about the mechanisms of air entry into xylem conduits. For conifers three mechanisms have been proposed: (1) a rupture of pit margo microfibrils, (2) a displacement of the pit torus from its normal sealing position over the pit aperture, and (3) a rupture of an air-water menisci in a pore of the pit margo. In this article, we report experimental results on three coniferous species suggesting additional mechanisms. First, when xylem segments were injected with a fluid at a pressure sufficient to aspirate pit tori and well above the pressure for cavitation induction we failed to detect the increase in sample conductance that should have been caused by torus displacement from blocking the pit aperture or by membrane rupture. Second, by injecting xylem samples with different surfactant solutions, we found a linear relation between sample vulnerability to cavitation and fluid surface tension. This suggests that cavitation in conifers could also be provoked by the capillary failure of an air-water meniscus in coherence with the prediction of Young-Laplace's equation. Within the bordered pit membrane, the exact position of this capillary seeding is unknown. The possible Achilles' heel could be the seal between tori and pit walls or holes in the torus. The mechanism of water-stress-induced cavitation in conifers could then be relatively similar to the one currently proposed for angiosperms.

ns2np4 (n = 4, 5) lone pair triplets whirling in M*F2E3 (M* = Kr, Xe): Stereochemistry and ab initio analyses

NASA Astrophysics Data System (ADS)

Galy, Jean; Matar, Samir F.

2017-02-01

The stereochemistry of ns2np4 (n = 4, 5) lone pair LP characterizing noble gas Kr and Xe (labeled M*) in M*F2 difluorides is examined within coherent crystal chemistry and ab initio visualizations. M*2+ in such oxidation state brings three lone pairs (E) and difluorides are formulated M*F2E3. The analyses use electron localization function (ELF) obtained within density functional theory calculations showing the development of the LP triplets whirling {E3} quantified in the relevant chemical systems. Detailed ELF data analyses allowed showing that in α KrF2E3 and isostructural XeF2E3 difluorides the three E electronic clouds merge or hybridize into a torus and adopt a perfect gyration circle with an elliptical section, while in β KrF2 the network architecture deforms the whole torus into an ellipsoid shape. Original precise metrics are provided for the torus in the different compounds under study. In KrF2 the geometric changes upon β → α phase transition is schematized and mechanisms for the transformation with temperature or pressure are proposed. The results are further highlighted by electronic band structure calculations which show similar features of equal band gaps of 3 eV in both α and β KrF2 and a reorganization of frontier orbitals due to the different orientations of the F-Kr-F linear molecule in the two tetragonal structures.

Entanglement entropy and the colored Jones polynomial

NASA Astrophysics Data System (ADS)

Balasubramanian, Vijay; DeCross, Matthew; Fliss, Jackson; Kar, Arjun; Leigh, Robert G.; Parrikar, Onkar

2018-05-01

We study the multi-party entanglement structure of states in Chern-Simons theory created by performing the path integral on 3-manifolds with linked torus boundaries, called link complements. For gauge group SU(2), the wavefunctions of these states (in a particular basis) are the colored Jones polynomials of the corresponding links. We first review the case of U(1) Chern-Simons theory where these are stabilizer states, a fact we use to re-derive an explicit formula for the entanglement entropy across a general link bipartition. We then present the following results for SU(2) Chern-Simons theory: (i) The entanglement entropy for a bipartition of a link gives a lower bound on the genus of surfaces in the ambient S 3 separating the two sublinks. (ii) All torus links (namely, links which can be drawn on the surface of a torus) have a GHZ-like entanglement structure — i.e., partial traces leave a separable state. By contrast, through explicit computation, we test in many examples that hyperbolic links (namely, links whose complements admit hyperbolic structures) have W-like entanglement — i.e., partial traces leave a non-separable state. (iii) Finally, we consider hyperbolic links in the complexified SL(2,C) Chern-Simons theory, which is closely related to 3d Einstein gravity with a negative cosmological constant. In the limit of small Newton constant, we discuss how the entanglement structure is controlled by the Neumann-Zagier potential on the moduli space of hyperbolic structures on the link complement.

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

Virginia Finley

The results of the 1999 environmental surveillance and monitoring program for the Princeton Plasma Physics Laboratory (PPPL) are presented and discussed. The purpose of this report is to provide the U.S. Department of Energy and the public with information on the level of radioactive and non-radioactive pollutants (if any) that are added to the environment as a result of PPPL's operations. The report also summarizes environmental initiatives, assessments, and programs that were undertaken in 1999. The Princeton Plasma Physics Laboratory has engaged in fusion energy research since 1951. The long-range goal of the U.S. Magnetic Fusion Energy Research Program ismore » to create innovations to make fusion power a practical reality--an alternative energy source. 1999 marked the first year of National Spherical Torus Experiment (NSTX) operations and Tokamak Fusion Test Reactor (TFTR) dismantlement and deconstruction activities. A collaboration among fourteen national laboratories, universities, and research institutions, the NSTX is a major element in the U.S. Fusion Energy Sciences Program. It has been designed to test the physics principles of spherical torus (ST) plasmas. The ST concept could play an important role in the development of smaller, more economical fusion reactors. With its completion within budget and ahead of its target schedule, NSTX first plasma occurred on February 12, 1999. The 1999 performance of the Princeton Plasma Physics Laboratory was rated ''outstanding'' by the U.S. Department of Energy in the Laboratory Appraisal report issued early in 2000. The report cited the Laboratory's consistently excellent scientific and technological achievements, its successful management practices, and included high marks in a host of other areas including environmental management, employee health and safety, human resources administration, science education, and communications. Groundwater investigations continued under a voluntary agreement with the New Jersey Department of Environmental Protection. PPPL monitored for the presence of non-radiological contaminants, mainly volatile organic compounds (components of degreasing solvents). Monitoring revealed the presence of low levels of volatile organic compounds in an area adjacent to PPPL. Also, PPPL's radiological monitoring program characterized the ambient, background levels of tritium in the environment and from the TFTR stack; the data are presented in this report.« less

On the divergence of triangular and eccentric spherical sums of double Fourier series

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

Karagulyan, G A

We construct a continuous function on the torus with almost everywhere divergent triangular sums of double Fourier series. We also prove an analogous theorem for eccentric spherical sums. Bibliography: 14 titles.

Overview of torus magnet coil production at Fermilab for the Jefferson Lab 12-GeV Hall B upgrade

DOE PAGES

Krave, S.; Velev, G.; Makarov, A.; ...

2016-02-29

Fermi National Accelerator Laboratory (Fermilab) fabricated the torus magnet coils for the 12-GeV Hall B upgrade at Jefferson Lab (JLab). The production consisted of six large superconducting coils for the magnet and two spare coils. The toroidal field coils are approximately 2 m × 4 m × 5 cm thick. Each of these coils consists of two layers, each of which has 117 turns of copper-stabilized superconducting cable, which will be conduction cooled by supercritical helium. Due to the size of the coils and their unique geometry, Fermilab designed and fabricated specialized tooling and, together with JLab, developed unique manufacturingmore » techniques for each stage of the coil construction. Furthermore, this paper describes the tooling and manufacturing techniques required to produce the six production coils and the two spare coils needed by the project.« less