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Sample records for tf magnet insulation

  1. Analysis and tests of TF magnet insulation samples for the JET upgrade to 4 tesla

    CERN Document Server

    Miele, P; Bettinali, L; Kaye, A; Last, J; Papastergiou, S; Riccardo, V; Visca, E

    2000-01-01

    The JET Toroidal Field (TF) coils were originally designed for operation at 3.4 tesla. In order to upgrade the field to 4 tesla and thus improve the performance of the JET machine, new mechanical tests and analysis were carried out on the insulation of TF coil samples. They are aimed at investigating the mechanical properties and the status of the insulation in order to set allowable stresses and force limits. In particular since the shear stress in the insulation is strongly affected by the shear modulus of elasticity G, it is important to measure this parameter. A method for the measurement of G in glass-resin fibres, the V-notched beam method (Iosipescu method) , was applied. The particular shape of the rectangular Iosipescu V- notched sample and the particular modality of force application produce pure shear stress for a reliable measurement of the G value and of the shear strength of the insulation. The effect of temperature on these mechanical properties was also investigated. Results show higher averag...

  2. Magnetic field shielding effect for CFETR TF coil-case

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weiwei; Liu, Xufeng, E-mail: Lxf@ipp.ac.cn; Du, Shuangsong; Zheng, Jinxing

    2017-05-15

    Highlights: • The eddy current of CFETR vacuum vessel can be calculated by using a series of ideal current loops. • The shielding effect with different eddy current is studied by decomposing the exciting magnetic field as two orthogonal components. • The shielding effect can be determined from the rate of eddy current magnetic field to the external magnetic field. - Abstract: The operation of superconducting magnet for fusion device is under the complex magnetic field condition, which affect the stabilization of superconductor. The coil-case of TF coil can shield the magnetic field to some extent. The shielding effect is related to the eddy current of coil-case. The shielding effect with different eddy current is studied by decomposing the exciting magnetic field as two orthogonal components, respectively. The results indicate that the shielding effect of CFETR TF coil-case has obvious different with the different directional magnetic field, and it’s larger for tangential magnetic compared with that for normal field.

  3. Tape-wound toroidal (TF) magnet for ZEPHYR (Intermediate Report)

    International Nuclear Information System (INIS)

    Brossmann, U.; Gruber, J.E.; Haubenberger, W.D.; Jandl, O.; Soell, M.; Streibl, B.

    1979-11-01

    The report comprises three sections. Section A presents the essential features of the present design of a tape-wound magnet with respect to the magnetic, thermal and radiological loads resulting from the physical assumptions for the ZEPHYR experiment. The conceptual requirements for the liquid-nitrogen cooling of the magnet are given and concepts under discussion are presented. To allow a first pronouncement on the mechanical load capacity of critical magnet components, the results available from calculations and experiments relating to the conductor and insulation materials are interpreted. As investigation of the material properties must play an important role in consolidating the magnet concept, special sections of the report are devoted to this subject. Section B deals theoretically with the conductor material problem, reviews the available experimental results, both with respect to material properties and technical production, and takes a look ahead at future activities. The insulation material is treated on similar lines in Section C. (orig.) 891 HT/orig. 892 HIS

  4. Electrically Tunable Magnetism in Magnetic Topological Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-14

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators.

  5. Quench characterization and thermo hydraulic analysis of SST-1 TF magnet busbar

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A.N., E-mail: ansharma@ipr.res.in [Institute for Plasma Research, Gandhinagar (India); Pradhan, S. [Institute for Plasma Research, Gandhinagar (India); Duchateau, J.L. [CEA Cadarache, 13108 St Paul lez Durance Cedex (France); Khristi, Y.; Prasad, U.; Doshi, K.; Varmora, P.; Tanna, V.L.; Patel, D.; Panchal, A. [Institute for Plasma Research, Gandhinagar (India)

    2015-01-15

    Highlights: • Details of SST-1 TF busbar quench detection. • Simulation of slow propagating normal zone. • Thermo hydraulic analyses of TF busbar in current feeder system. - Abstract: Toroidal field (TF) magnet system of steady-state superconducting tokamak-1 (SST-1) has 16 superconducting coils. TF coils are cooled with forced flow supercritical helium at 0.4 MPa, at 4.5 K and operate at nominal current of 10,000 A. Prior to TF magnet system assembly in SST-1 tokamak, each TF coil was tested individually in a test cryostat. During these tests, TF coil was connected to a pair of conventional helium vapor cooled current leads. The connecting busbar was made from the same base cable-in-conduit-conductor (CICC) of SST-1 superconducting magnet system. Quenches experimentally observed in the busbar sections of the single coil test setups have been analyzed in this paper. A steady state thermo hydraulic analysis of TF magnet busbar in actual SST-1 tokamak assembly has been done. The experimental observations of quench and results of relevant thermo hydraulic analyses have been used to predict the safe operation regime of TF magnet system busbar during actual SST-1 tokamak operational scenarios.

  6. Electrical insulation for large multiaxis superconducting magnets

    International Nuclear Information System (INIS)

    Harvey, A.R.; Rinde, J.A.

    1975-01-01

    The selection of interturn and interlayer insulation for superconducting magnets is discussed. The magnet problems of the Baseball II device are described. Manufacture of the insulation and radiation damage are mentioned. A planned experimental program is outlined

  7. Engineering, Manufacture and Preliminary Testing of the ITER Toroidal Field (TF) Magnet Helium Cold Circulator

    Science.gov (United States)

    Rista, P. E. C.; Shull, J.; Sargent, S.

    2015-12-01

    The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency's (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying helium cold circulators worldwide over a period of 35 years. Features include a vacuum-jacketed hermetically sealed design with a very low helium leak rate, a heat shield for use with both nitrogen & helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator must be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED) including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper.

  8. Engineering, Manufacture and Preliminary Testing of the ITER Toroidal Field (TF) Magnet Helium Cold Circulator

    International Nuclear Information System (INIS)

    C Rista, P E; Shull, J; Sargent, S

    2015-01-01

    The ITER cryodistribution system provides the supercritical Helium (SHe) forced flow cooling to the magnet system using cold circulators. The cold circulators are located in each of five separate auxiliary cold boxes planned for use in the facility. Barber-Nichols Inc. has been awarded a contract from ITER-India for engineering, manufacture and testing of the Toroidal Field (TF) Magnet Helium Cold Circulator. The cold circulator will be extensively tested at Barber-Nichols’ facility prior to delivery for qualification testing at the Japan Atomic Energy Agency's (JAEA) test facility at Naka, Japan. The TF Cold Circulator integrates features and technical requirements which Barber-Nichols has utilized when supplying helium cold circulators worldwide over a period of 35 years. Features include a vacuum-jacketed hermetically sealed design with a very low helium leak rate, a heat shield for use with both nitrogen and helium cold sources, a broad operating range with a guaranteed isentropic efficiency over 70%, and impeller design features for high efficiency. The cold circulator will be designed to meet MTBM of 17,500 hours and MTBF of 36,000 hours. Vibration and speed monitoring are integrated into a compact package on the rotating assembly with operation and health monitoring in a multi-drop PROFIBUS communication environment using an electrical cabinet with critical features and full local and network PLC interface and control. For the testing in Japan and eventual installation in Europe, the cold circulator must be certified to the Japanese High Pressure Gas Safety Act (JHPGSA) and CE marked in compliance with the European Pressure Equipment Directive (PED) including Essential Safety Requirements (ESR). The test methodology utilized at Barber-Nichols’ facility and the resulting test data, validating the high efficiency of the TF Cold Circulator across a broad operating range, are important features of this paper. (paper)

  9. Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

    International Nuclear Information System (INIS)

    Simon, N.J.

    1994-01-01

    Results of a literature search on the cryogenic properties of candidate inorganic insulators for the ITER TF magnets are reported. The materials investigated include: Al 2 O 3 , AlN, MgO, porcelain, SiO 2 , MgAl 2 O 4 , ZrO 2 , and mica. A graphical presentation is given of mechanical, elastic, electrical, and thermal properties between 4 and 300 K. A companion report reviews the low temperature irradiation resistance of these materials

  10. Room Temperature Magnetic Determination of the Current Center Line for the ITER TF Coils

    CERN Document Server

    Lerch, Philippe; Buzio, Marco; Negrazus, Marco; Baynham, Elwyn; Sanfilippo, Stephane; Foussat, Arnaud

    2014-01-01

    The ITER tokamak includes 18 superconducting D-shaped toroidal field (IT) coils. Unavoidable shape deformations as well as assembly errors will lead to field errors, which can be modeled with the knowledge of the current center line (CCL). Accurate survey during the entire manufacturing and assembly process, including transfer of survey points, is complex. In order to increase the level of confidence, a room temperature magnetic measurement of the CCL on assembled and closed winding packs is foreseen, prior to insertion into their cold case. In this contribution, we discuss the principle of the CCL determination and present a low frequency ac measurement system under development at PSI, within an ITER framework contract. The largest current allowed to flow in the TF coil at room temperature and the precision requirements for the determination of the CCL loci of the coil are hard boundaries. Eddy currents in the radial plates, the winding pack enclosures, and possibly from iron in the reinforced concrete floor...

  11. Improved cable insulation for superconducting magnets

    International Nuclear Information System (INIS)

    Anerella, M.; Ghosh, A.K.; Kelly, E.; Schmalzle, J.; Willen, E.; Fraivillig, J.; Ochsner, J.; Parish, D.J.

    1993-01-01

    Several years ago, Brookhaven joined with DuPont in a cooperative effort to develop improved cable insulation for SSC superconducting dipole magnets. The effort was supported by the SSC Central Design Group and later the SSC Laboratory. It was undertaken because turn-to-turn and midplane shorts were routinely being experienced during the assembly of magnets with coils made of the existing Kapton/Fiberglass (K/FG) system of Kapton film overwrapped with epoxy-impregnated fiberglass tape. Dissection of failed magnets showed that insulation disruption and punch-through was occurring near the inner edges of turns close to the magnet midplane. Coil pressures of greater than 17 kpsi were sufficient to disrupt the insulation at local high spots where wires in neighboring turns crossed one another and where the cable had been strongly compacted in the keystoning operation during cable manufacture. In the joint development program, numerous combinations of polyimide films manufactured by DuPont with varying configurations and properties (including thickness) were subjected to tests at Brookhaven. Early tests were bench trials using wrapped cable samples. The most promising candidates were used in coils and many of these assembled and tested as magnets in both the SSC and RHIC magnet programs currently underway. The Kapton CI (CI) system that has been adopted represents a suitable compromise of numerous competing factors. It exhibits improved performance in the critical parameter of compressive punch-through resistance as well as other advantages over the K/FG system

  12. Self-magnetically insulated ion diode

    International Nuclear Information System (INIS)

    VanDevender, J.; Quintenz, J.; Leeper, R.; Johnson, D.; Crow, J.

    1981-01-01

    Light ion diodes for producing 1--100 TW ion beams are required for inertial confinement fusion. The theory, numerical simulations, and experiments on a self-magnetically insulated ion diode are presented. The treatment is from the point of view of a self-magnetically insulated transmission line with an ion loss current and differs from the usual treatment of the pinched electron beam diode. The simulations show that the ratio V/IZ 0 =0.25 in such a structure with voltage V, local total current I, and local vacuum wave impedance Z 0 . The ion current density is enhanced by a factor of approximately 2 over the simple space-charge limited value. The simulation results are verified in an experiment. An analytical theory is then presented for scaling the results to produce a focused beam of protons with a power of up to 10 13 W

  13. Magnon-polaron transport in magnetic insulators

    Science.gov (United States)

    Flebus, Benedetta; Shen, Ka; Kikkawa, Takashi; Uchida, Ken-ichi; Qiu, Zhiyong; Saitoh, Eiji; Duine, Rembert A.; Bauer, Gerrit E. W.

    2017-04-01

    We theoretically study the effects of strong magnetoelastic coupling on the transport properties of magnetic insulators. We develop a Boltzmann transport theory for the mixed magnon-phonon modes ("magnon polarons") and determine transport coefficients and the spin diffusion length. Magnon-polaron formation causes anomalous features in the magnetic field and temperature dependence of the spin Seebeck effect when the disorder scattering in the magnetic and elastic subsystems is sufficiently different. Experimental data by Kikkawa et al. [Phys. Rev. Lett. 117, 207203 (2016), 10.1103/PhysRevLett.117.207203] on yttrium iron garnet films can be explained by an acoustic quality that is much better than the magnetic quality of the material. We predict similar anomalous features in the spin and heat conductivity and nonlocal spin transport experiments.

  14. Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Simon, N.J.

    1994-12-01

    Results of a literature search on the cryogenic properties of candidate inorganic insulators for the ITER TF magnets are reported. The materials investigated include: Al{sub 2}O{sub 3}, AlN, MgO, porcelain, SiO{sub 2}, MgAl{sub 2}O{sub 4}, ZrO{sub 2}, and mica. A graphical presentation is given of mechanical, elastic, electrical, and thermal properties between 4 and 300 K. A companion report reviews the low temperature irradiation resistance of these materials.

  15. Magnon Valve Effect between Two Magnetic Insulators

    Science.gov (United States)

    Wu, H.; Huang, L.; Fang, C.; Yang, B. S.; Wan, C. H.; Yu, G. Q.; Feng, J. F.; Wei, H. X.; Han, X. F.

    2018-03-01

    The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

  16. Qualification of the US Made Conductors for ITER TF Magnet System

    International Nuclear Information System (INIS)

    Martovetsky, Nicolai N.; Hatfield, Daniel R.; Miller, John R.; Bruzzone, P.; Stepanov, B.; Seber, B.

    2010-01-01

    The US Domestic Agency (USDA) is one of the six suppliers of the Toroidal Field (TF) conductor for the International Thermonuclear Experimental Reactor (ITER). In order to qualify conductors according to ITER requirements we prepared several lengths of the CICC and short samples for testing in the SULTAN facility in CRPP, Switzerland. We also fully characterized the strands that were used in these SULTAN samples. Fabrication experience and test results are presented and discussed.

  17. Electrically tuned magnetic order and magnetoresistance in a topological insulator.

    Science.gov (United States)

    Zhang, Zuocheng; Feng, Xiao; Guo, Minghua; Li, Kang; Zhang, Jinsong; Ou, Yunbo; Feng, Yang; Wang, Lili; Chen, Xi; He, Ke; Ma, Xucun; Xue, Qikun; Wang, Yayu

    2014-09-15

    The interplay between topological protection and broken time reversal symmetry in topological insulators may lead to highly unconventional magnetoresistance behaviour that can find unique applications in magnetic sensing and data storage. However, the magnetoresistance of topological insulators with spontaneously broken time reversal symmetry is still poorly understood. In this work, we investigate the transport properties of a ferromagnetic topological insulator thin film fabricated into a field effect transistor device. We observe a complex evolution of gate-tuned magnetoresistance, which is positive when the Fermi level lies close to the Dirac point but becomes negative at higher energies. This trend is opposite to that expected from the Berry phase picture, but is intimately correlated with the gate-tuned magnetic order. The underlying physics is the competition between the topology-induced weak antilocalization and magnetism-induced negative magnetoresistance. The simultaneous electrical control of magnetic order and magnetoresistance facilitates future topological insulator based spintronic devices.

  18. Enhanced thermoelectric power in ultrathin topological insulators with magnetic doping

    KAUST Repository

    Tahir, M.

    2014-09-07

    We derive analytical expressions for the magnetic moment and orbital magnetization as well as for the corresponding thermal conductivity and thermoelectric power of a topological insulator film. We demonstrate enhancement of the thermoelectric transport for decreasing film thickness and for application of an exchange field due to the tunable band gap. Combining hybridization and exchange field is particularly suitable for heat to electric energy conversion and thermoelectric cooling.

  19. Evaluation of Magnetic Insulation in SF6 Filled Regions

    Energy Technology Data Exchange (ETDEWEB)

    Houck, T; Ferriera, T; Goerz, D; Javedani, J; Speer, R; Tully, L; Vogtlin, G

    2009-06-08

    The use of magnetic fields perpendicular to quasistatic electric fields to deter electrical breakdown in vacuum, referred to as magnetic insulation, is well understood and used in numerous applications. Here we define quasi-static as applied high-voltage pulse widths much longer than the transit time of light across the electrode gap. For this report we extend the concept of magnetic insulation to include the inhibition of electrical breakdown in gases. Ionization and electrical breakdown of gases in crossed electric and magnetic fields is only a moderately explored research area. For sufficiently large magnetic fields an electron does not gain sufficient energy over a single cycloidal path to ionize the gas molecules. However, it may be possible for the electron to gain sufficient energy for ionization over a number of collisions. To study breakdown in a gas, the collective behavior of an avalanche of electrons in the formation of a streamer in the gas is required. Effective reduced electric field (EREF) theory, which considers the bulk properties of an electron avalanche, has been successful at describing the influence of a crossed magnetic field on the electric field required for breakdown in gases; however, available data to verify the theory has been limited to low gas pressures and weak electronegative gases. High power devices, for example explosively driven magnetic flux compressors, operate at electrical field stresses, magnetic fields, and insulating gas pressures nearly two orders of magnitude greater than published research for crossed fields in gases. The primary limitation of conducting experiments at higher pressures, e.g. atmospheric, is generating the large magnetic fields, 10's Tesla, and electric fields, >100 kV/cm, required to see a significant effect. In this paper we describe measurements made with a coaxial geometry diode, form factor of 1.2, operating at peak electrical field stress of 220 kV/cm, maximum magnetic field of 20 Tesla, and

  20. Coupling of an applied field magnetically insulated ion diode to a high power magnetically insulated transmission line system

    International Nuclear Information System (INIS)

    Maenchen, J.E.

    1983-01-01

    The coupling of energy from a high power pulsed accelerator through a long triplate magnetically insulated transmission line (MITL) in vacuum to an annular applied magnetic field insulated extraction ion diode is examined. The narrow power transport window and the wave front erosion of the MITL set stringent impedance history conditions on the diode load. A new ion diode design developed to satisfy these criteria with marginal electron insulation is presented. The LION accelerator is used to provide a positive polarity 1.5 MV, 350 kA, 40 ns FWHM pulse with a 30 kA/ns current rate from a triplate MITL source. A transition converts the triplate into a cylindrical cross section which flares into the ion diode load. Extensive current and voltage measurements performed along this structure and on the extracted ion beam provide conclusive evidence that the self insulation condition of the MITL is maintained in the transition by current loss alone. The ion diode utilizes a radial magnetic field between a grounded cathode annular emission tip and a disk anode. A 50 cm 2 dielectric/metal anode area serves as the ion plasma source subject to direct electron bombardment from the opposing cathode tip under marginal magnetic insulation conditions. The ions extracted cross the radial magnetic field and exit the diode volume as an annular cross section beam of peak current about 100 kA. The diode current gradually converts from the initial electron flow to nearly 100% ion current after 30 ns, coupling 60% of the diode energy into ions

  1. A magnetic monopole in topological insulator: exact solution

    OpenAIRE

    Zhao, Yuan-Yuan; Shen, Shun-Qing

    2012-01-01

    The Witten effect tells that a unit magnetic monopole can bind a half elementary charge in an axion media. We present an exact solution of a magnetic monopole in a topological insulator that was proposed to be an axion media recently. It is found that a magnetic monopole can induce one zero energy state bound to it and one surface state of zero energy. The two states are quite robust, but the degeneracy can be removed by external fields. For a finite size system, the interference of two state...

  2. Spintronics current-switched magnetic insulator

    Czech Academy of Sciences Publication Activity Database

    Wunderlich, Joerg

    2017-01-01

    Roč. 16, č. 3 (2017), s. 284-285 ISSN 1476-1122 Institutional support: RVO:68378271 Keywords : spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 39.737, year: 2016

  3. Tailoring of electron flow current in magnetically insulated transmission lines

    Directory of Open Access Journals (Sweden)

    J. P. Martin

    2009-03-01

    Full Text Available It is desirable to optimize (minimizing both the inductance and electron flow the magnetically insulated vacuum sections of low impedance pulsed-power drivers. The goal of low inductance is understandable from basic efficiency arguments. The goal of low electron flow results from two observations: (1 flowing electrons generally do not deliver energy to (or even reach most loads, and thus constitute a loss mechanism; (2 energetic electrons deposited in a small area can cause anode damage and anode plasma formation. Low inductance and low electron flow are competing goals; an optimized system requires a balance of the two. While magnetically insulated systems are generally forgiving, there are times when optimization is crucial. For example, in large pulsed-power drivers used to energize high energy density physics loads, the electron flow as a fraction of total current is small, but that flow often reaches the anode in relatively small regions. If the anode temperature becomes high enough to desorb gas, the resulting plasma initiates a gap closure process that can impact system performance. Magnetic-pressure driven (z pinches and material equation of state loads behave like a fixed inductor for much of the drive pulse. It is clear that neither fixed gap nor constant-impedance transmission lines are optimal for driving inductive loads. This work shows a technique for developing the optimal impedance profile for the magnetically insulated section of a high-current driver. Particle-in-cell calculations are used to validate the impedance profiles developed in a radial disk magnetically insulated transmission line geometry. The input parameters are the spacing and location of the minimum gap, the effective load inductance, and the desired electron flow profile. The radial electron flow profiles from these simulations are in good agreement with theoretical predictions when driven at relatively high voltage (i.e., V≥2  MV.

  4. Magnetically Defined Qubits on 3D Topological Insulators

    Science.gov (United States)

    Ferreira, Gerson J.; Loss, Daniel

    2014-03-01

    We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect. Here, we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots, we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits. See [Ferreira and Loss, Phys. Rev. Lett. 111, 106802 (2013)]. We explore potentials that break time-reversal symmetry to confine the surface states of 3D topological insulators into quantum wires and quantum dots. A magnetic domain wall on a ferromagnet insulator cap layer provides interfacial states predicted to show the quantum anomalous Hall effect. Here, we show that confinement can also occur at magnetic domain heterostructures, with states extended in the inner domain, as well as interfacial QAHE states at the surrounding domain walls. The proposed geometry allows the isolation of the wire and dot from spurious circumventing surface states. For the quantum dots, we find that highly spin-polarized quantized QAHE states at the dot edge constitute a promising candidate for quantum computing qubits. See [Ferreira and Loss, Phys. Rev. Lett. 111, 106802 (2013)]. We acknowledge support from the Swiss NSF, NCCR Nanoscience, NCCR QSIT, and the Brazillian Research Support Center Initiative (NAP Q-NANO) from Pró-Reitoria de Pesquisa (PRP/USP).

  5. Superconductivity in an Organic Insulator at Very High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Balicas, L.; Brooks, J. S.; Storr, K.; Uji, S.; Tokumoto, M.; Tanaka, H.; Kobayashi, H.; Kobayashi, A.; Barzykin, V.; Gor' kov, L. P.

    2001-08-06

    We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor {lambda}-(BETS){sub 2}FeCl{sub 4} . Below 4K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41T and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe{sup 3+} ions. We further argue that the Fe{sup 3+} moments are essential to stabilize the resulting singlet, two-dimensional superconducting state.

  6. Superconductivity in an organic insulator at very high magnetic fields.

    Science.gov (United States)

    Balicas, L; Brooks, J S; Storr, K; Uji, S; Tokumoto, M; Tanaka, H; Kobayashi, H; Kobayashi, A; Barzykin, V; Gor'kov, L P

    2001-08-06

    We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor lambda-(BETS)2FeCl4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe3+ ions. We further argue that the Fe3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state.

  7. Observation of the Quantum-Anomalous-Hall Insulator to Anderson Insulator Quantum Phase Transition in Magnetic Topological Insulators

    Science.gov (United States)

    Chang, Cui-Zu; Zhao, Wei-Wei; Li, Jian; Jain, J. K.; Liu, Chaoxing; Moodera, Jagadeesh S.; Chan, Moses H. W.

    The quantum anomalous Hall (QAH) effect can be considered as the quantum Hall (QH) effect without external magnetic field, which can be realized by time reversal symmetry breaking in a topologically non-trivial system, and in thin films of magnetically-doped TI. A QAH system carries spin-polarized dissipationless chiral edge transport channels without the need for external energy input, hence may have huge impact on future electronic and spintronic device applications for ultralow-power consumption. The observation of QAH effect has opened up exciting new physics and thus understanding the physical nature of this novel topological quantum state, can lead to a rapid development of this field. In this talk, we will report our recent progress about the experimental observation of a quantum phase transition from a quantum-anomalous-Hall (QAH) insulator to an Anderson insulator by tuning the chemical potential, and finally discuss the existence of scaling behavior for this quantum phase transition. Work Supported by funding from NSF (DMR-1207469), NSF (DMR-0819762) (MIT MRSEC), ONR (N00014-13-1-0301), and the STC Center for Integrated Quantum Materials under NSF Grant DMR-1231319.

  8. High voltage diagnostics on electrical insulation of supersonducting magnets

    International Nuclear Information System (INIS)

    Irmisch, M.

    1995-12-01

    The high voltage (HV) performance of superconducting magnets of large dimensions, e.g. as needed in fusion reactors, is a challange in the field of high voltage technology, i.e. especially in the field of cryogenic high voltage components and with respect to questions of HV insulation diagnostics at low temperature. By using the development of POLO - a superconducting prototype coil of a tokamak poloidal field coil - as an example, this work deals with special problems of how to get use of conventional HV test techniques for diagnostics under special cryogenic boundary conditions. As a first approach to gain experience in the field of phase resolved partial discharge (PRPD) measurements during operation of a superconductive coil, the POLO coil was subject to several high voltage tests. Compared with DC insulation resistance measurements and capacitive impulse voltage discharges to the coil, the AC PD measurements have been the only way to observe special characteristics of the electrical insulation with respect to the cooling down of the coil from 300 K to 4.2 K. The PRPD measurement technique thereby has proofed as a suitable diagnostic tool. This work can serve as basic data to be comparable within further projects of electrical insulation diagnostics at cryogenic temperatures. (orig.)

  9. Magnetic field dependence of the magnon spin diffusion length in the magnetic insulator yttrium iron garnet

    NARCIS (Netherlands)

    Cornelissen, L. J.; van Wees, B. J.

    2016-01-01

    We investigated the effect of an external magnetic field on the diffusive spin transport by magnons in the magnetic insulator Y3Fe5O12, using a nonlocal magnon transport measurement geometry. We observed a decrease in magnon spin diffusion length lambda(m) for increasing field strengths, where

  10. Reactor potential of the magnetically insulated inertial fusion (MICF) system

    International Nuclear Information System (INIS)

    Kammash, T.; Galbraith, D.L.

    1987-01-01

    The Magnetically Insulated Inertial Confinement Fusion (MICF) scheme is examined with regard to its potential as a power-producing reactor. This approach combines the favorable aspects of both magnetic and inertial fusions in that physical containment of the plasma is provided by a metallic shell while thermal insulation of its energy is provided by a strong, self-generated magnetic field. The plasma is created at the core of the target as a result of irradiation of the fuel-coated inner surface by a laser beam that enters through a hole in the spherical shell. The instantaneous magnetic field is generated by the current loops formed by the laser-heated, laser-ablated electrons, and preliminary experimental results at Osaka University have confirmed the presence of such a field. These same experiments have also yielded a Lawson parameter of about 5x10 12 cm -3 sec, and because of these unique properties, the plasma lifetimes in MICF have been shown to be about two orders of magnitude longer than conventional, pusher type inertial fusion schemes. In this paper a quasi one dimensional, time dependent set of particle and energy balance equations for the thermal species, namely, electrons, ions and thermal alphas which also allows for an appropriate set of fast alpha groups is utilized to assess the reactor prospects of a DT-burning MICF system. (author) [pt

  11. Magnetic vortex crystals in frustrated 3D Mott insulators

    Science.gov (United States)

    Wang, Zhentao; Kamiya, Yoshitomo; Nevidomskyy, Andriy; Batista, Cristian

    2015-03-01

    Topological spin textures, such as skyrmions, are of great interest to the field of spintronics and usually arise due to the interplay of Dzyaloshinskii-Moriya and exchange couplings. By contrast, using the BCC and FCC lattices as examples, here we demonstrate that frustrated spin exchange interactions alone can produce topological vortex crystals near the magnetic field-induced saturation transition of 3D bulk Mott insulators. Because of the magnetic frustration, the magnon spectrum of the high-field fully polarized state has multiple degenerate minima at different Q-vectors. This quantum paramagnet becomes gapless and goes through a Bose-Einstein condensation at the saturation field (quantum critical point). In this limit, we apply the dilute bosonic gas approximation to study the rich topological structures produced due to multi-Q condensation. We find that the vortex crystal phases span sizable regions in the phase diagrams of frustrated 3D Mott insulators with isotropic Heisenberg interactions, and are further stabilized by exchange anisotropies. Vortex strings emerge in the direction of the magnetic field and, depending on the distributions of the condensed modes, can form different exotic patterns.

  12. Cloaking magnetic field and generating electric field with topological insulator and superconductor bi-layer sphere

    Science.gov (United States)

    Xu, Jin

    2017-12-01

    When an electric field is applied on a topological insulator, not only the electric field is generated, but also the magnetic field is generated, vice versa. I designed topological insulator and superconductor bi-layer magnetic cloak, derived the electric field and magnetic field inside and outside the topological insulator and superconductor sphere. Simulation and calculation results show that the applied magnetic field is screened by the topological insulator and superconductor bi-layer, and the electric field is generated in the cloaked region.

  13. Magnetic insulation to improve voltage holding in electrostatic accelerators

    International Nuclear Information System (INIS)

    Grisham, L. R.

    2009-01-01

    Voltage holding in high voltage electrostatic accelerators is a longstanding problem which limits the practically obtainable performance of most systems. This paper proposes an idea for improving the voltage holding in electrostatic accelerators by suppressing breakdowns between successive stages of an accelerator. The idea consists of flowing electric currents along the accelerator electrodes to produce magnetic fields which envelope each electrode and its support structure, so as to prevent very low energy electrons from leaving the surfaces of electrodes and subsequently picking up energy from the electric field. In order to be useful in some applications, this magnetic insulation would only need to produce modest gains in voltage holding capability, and its utility can be easily tested experimentally as described herein.

  14. Requirements for self-magnetically insulated transmission lines

    Directory of Open Access Journals (Sweden)

    J. Pace VanDevender

    2015-03-01

    Full Text Available Self-magnetically insulated transmission lines (MITLs connect pulsed-power drivers with a load. Although the technology was originally developed in the 1970s and is widely used today in super power generators, failure of the technology is the principal limitation on the power that can be delivered to an experiment. We address issues that are often overlooked, rejected after inadequate simulations, or covered by overly conservative assumptions: (i electron retrapping in coupling MITLs to loads, (ii the applicability of collisionless versus collisional electron flow, (iii power transport efficiency as a function of the geometry at the beginning of the MITL, (iv gap closure and when gap closure can be neglected, and (v the role of negative ions in causing anode plasmas and enhancing current losses. We suggest a practical set of conservative design requirements for self-magnetically insulated electron flow based on the results discussed in this paper and on previously published results. The requirements are not necessarily severe constraints in all MITL applications; however, each of the 18 suggested requirements should be examined in the design of a MITL and in the investigation of excessive losses.

  15. Production and Characterization of Ion Beams from Magnetically Insulated Diodes.

    Science.gov (United States)

    Neri, Jesse Martin

    1982-03-01

    The operation of magnetically insulated diodes and the characteristics of the resulting ion beams have been investigated using two pulsed power generators, LYNX at the 10('9)W power level, and Neptune at the 10('11)W power level. LYNX is a small magnetically insulated diode driven directly by a Marx bank. By changing the material used as the surface flashover ion source, the majority ion species generated by the diode could be chosen. Ion beams produced so far by this device are: protons, lithium, boron, carbon, sodium, strontium, and barium. Typical beam parameters for the ion beams are peak energies of 300 keV, current densities of 40-60 A/cm('2,) and pulse durations of 300 -400 nsec. The ion beam uniformity, divergence, and reproducibility were shown to be a function of the surface flashover source geometry. Finally, the LYNX ion beam was also used to anneal silicon crystals and other materials science experiments. The diode used on the Neptune generator was designed to study virtual cathode formation in a high power magnetically insulated diode. The physical cathode was replaced by electrons that ExB drift on the applied magnetic field lines. It was found that the best electrode configuration is one in which the electrons are required to only undergo the Hall drift to form the cathode. The divergence of the ion beam was examined with time-dependent and time -integrated shadowbox diagnostics. It was found that the intrinsic divergence of the ion beam does not have a strong directional dependence. However, the beam suffers a time -dependent aiming error in the plane of the ion beam acceleration and the Hall drift, which is attributed to the dynamics of the virtual cathode electrons. Low time-integrated divergence of the ion beam was attributed to the portion of the ion beam that was carbon (typically 50%). Analysis and discussion of the results is presented on the anode plasma formation and heating process, the virtual cathode flow in the Neptune diode, and the

  16. Fatigue effects in insulation materials for fusion magnets

    International Nuclear Information System (INIS)

    Rosenkranz, P.

    2000-12-01

    The mechanical properties of insulation materials for the superconducting magnets of ITER (International Thermonuclear Experimental Reactor) and future fusion plants, i.e. woven fiber reinforced composites, have been identified as an area of concern for the long-term operation of such magnets. The magnets will be subjected to fast neutron and γ-radiation over their lifetime, which influence the mechanical properties of the insulation materials. The ultimate tensile strength and, above all, the interlaminar shear strength and their performance under dynamic load, corresponding to the pulsed operation of a TOKAMAK-confinement system, are sensitive indicators of material failure in fiber-reinforced laminates especially at cryogenic temperatures. To simulate these conditions, low frequency fatigue measurements at 10 Hz were made at 77 K up to one million cycles. Tension-tension fatigue tests were performed according to ASTM D3479. However, due to the space limitations in all irradiation facilities, the tests have to be done on samples, which are considerably smaller than those required for standard test conditions. The influence of the specimen geometry on the ultimate tensile strength under static and dynamic load conditions was, therefore, investigated on fiber-reinforced plastics. They did not show any systematic trends as long as the sample thickness does not exceed the thickness recommended in ASTM D3479. The double lap shear test method was chosen for the shear experiments because of the symmetry of the specimen geometry under tensile load and the suitability for fatigue tests. Like almost every existing test procedure for the interlaminar shear strength, this test method does not provide for a completely uniform interlaminar shear stress distribution over a sizable region in the test section of the specimen. A scaling program combined with FE-simulations was, therefore, initiated to assess the influence of the length of the test section and of the sample

  17. Observation of the spin Peltier effect for magnetic insulators.

    Science.gov (United States)

    Flipse, J; Dejene, F K; Wagenaar, D; Bauer, G E W; Ben Youssef, J; van Wees, B J

    2014-07-11

    We report the observation of the spin Peltier effect (SPE) in the ferrimagnetic insulator yttrium iron garnet (YIG), i.e., a heat current generated by a spin current flowing through a platinum (Pt)|YIG interface. The effect can be explained by the spin transfer torque that transforms the spin current in the Pt into a magnon current in the YIG. Via magnon-phonon interactions the magnetic fluctuations modulate the phonon temperature that is detected by a thermopile close to the interface. By finite-element modeling we verify the reciprocity between the spin Peltier and spin Seebeck effect. The observed strong coupling between thermal magnons and phonons in YIG is attractive for nanoscale cooling techniques.

  18. Extraction magnetically insulated diode studies on Gamble II

    International Nuclear Information System (INIS)

    Neri, J.M.; Boller, J.R.; Ottinger, P.F.; Stephanakis, S.J.; Greenly, J.

    1993-01-01

    An extraction Magnetically Insulated Diode (MID) with anode and cathode magnetic field coils has been tested on the NRL Gamble II accelerator. The purpose of the experiments is to develop an annular, intense ion beam source for testing ion beam transport physics related to light ion inertial confinement fusion. Initial experiments have been performed with surface flashover ion sources. The experimental challenge has been to obtain a tuning of the 4 magnetic field coils that results in a minimum turn-on time of the ion source and acceptable coupling to the accelerator. Results from several different geometries of magnetic field will be presented. The principal diode diagnostics are the total diode current, net ion current, and corrected diode voltage. Calculations of the magnetic field strength and geometry are performed with the ATHETA code. An active anode ion source is also under development. The initial portion of the accelerator pulse is diverted with a plasma opening switch (POS) and passed through a thin foil that will become the ion source. The foil is swiftly heated by the current pulse and gas is desorbed or diffused from the foil into the anode-cathode gap. The gas is then broken down by the current pulse, forming a dense plasma source on the anode surface. Two different foils are being used. A thin aluminum foil will work with desorbed gases, and provide a beam that is predominately protons. A hydrogen loaded titanium foil, with a paladium overcoating, will use diffused hydrogen, and produce a high purity proton beam. The net result of the POS and active anode plasma source should be much faster ion turn-on time, and better coupling of the ion source to the accelerator. Preliminary results with the active anode sources will be presented

  19. Cable Insulation Scheme to Improve Heat Transfer to Superfluid Helium in Nb-Ti Accelerator Magnets

    CERN Document Server

    La China, M

    2008-01-01

    In superconducting magnets operating at high heat loads as the ones for interaction region of particle colliders or for fast cycling synchrotrons, the limited heat transfer capability of state-of-the-art electrical insulation may constitute a heavy limitation to performance. In the LHC main magnets, Nb-Ti epoxy-free insulation, composed of polyimide tapes, has proved to be permeable to superfluid helium, however the heat flux is rather limited. After a review of the standard insulation scheme for Nb-Ti and of the associated heat transfer mechanisms, we show the existence of a large margin available to improve insulation permeability.We propose a possible way to profit of such a margin in order to increase significantly the maximum heat flux drainable from an all polyimide insulated Nb-Ti coil, as it is used in modern accelerator magnets.

  20. Millimeter-Gap Magnetically Insulated Transmission Line Power Flow Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Hutsel, Brian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stoltzfus, Brian S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fowler, William E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); LeChien, Keith R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mazarakis, Michael G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moore, James K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mulville, Thomas D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Savage, Mark E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stygar, William A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McKenney, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jones, Peter A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); MacRunnels, Diego J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Long, Finis W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Porter, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    An experiment platform has been designed to study vacuum power flow in magnetically insulated transmission lines (MITLs). The platform was driven by the 400-GW Mykonos-V accelerator. The experiments conducted quantify the current loss in a millimeter-gap MITL with respect to vacuum conditions in the MITL for two different gap distances, 1.0 and 1.3 mm. The current loss for each gap was measured for three different vacuum pump down times. As a ride along experiment, multiple shots were conducted with each set of hardware to determine if there was a conditioning effect to increase current delivery on subsequent shots. The experiment results revealed large differences in performance for the 1.0 and 1.3 mm gaps. The 1.0 mm gap resulted in current loss of 40%-60% of peak current. The 1.3 mm gap resulted in current losses of less than 5% of peak current. Classical MITL models that neglect plasma expansion predict that there should be zero current loss, after magnetic insulation is established, for both of these gaps. The experiments result s indicate that the vacuum pressure or pump down time did not have a significant effect on the measured current loss at vacuum pressures between 1e-4 and 1e-5 Torr. Additionally, there was not repeatable evidence of a conditioning effect that reduced current loss for subsequent full-energy shots on a given set of hardware. It should be noted that the experiments conducted likely did not have large loss contributions due to ion emission from the anode due to the relatively small current densi-ties (25-40 kA/cm) in the MITL that limited the anode temperature rise due to ohmic heating. The results and conclusions from these experiments may have limited applicability to MITLs of high current density (>400 kA/cm) used in the convolute and load region of the Z which experience temperature increases of >400° C and generate ion emission from anode surfaces.

  1. Magnetic excitations and amplitude fluctuations in insulating cuprates

    Science.gov (United States)

    Chelwani, N.; Baum, A.; Böhm, T.; Opel, M.; Venturini, F.; Tassini, L.; Erb, A.; Berger, H.; Forró, L.; Hackl, R.

    2018-01-01

    We present results from light scattering experiments on three insulating antiferromagnetic cuprates, YBa2Cu3O6.05 , Bi2Sr2YCu2O8 +δ , and La2CuO4 as a function of polarization and excitation energy using samples of the latest generation. From the raw data we derive symmetry-resolved spectra. The spectral shape in B1 g symmetry is found to be nearly universal and independent of excitation energy. The spectra agree quantitatively with predictions by field theory [Eur. Phys. J. B 88, 237 (2015), 10.1140/epjb/e2015-60438-1] facilitating the precise extraction of the Heisenberg coupling J . In addition, the asymmetric lineshape on the high-energy side is found to be related to amplitude fluctuations of the magnetization. In La2CuO4 alone, minor contributions from resonance effects may be identified. The spectra in the other symmetries are not universal. The variations may be traced back to weak resonance effects and extrinsic contributions. For all three compounds we find support for the existence of chiral excitations appearing as a continuum in A2 g symmetry having an onset slightly below 3 J . In La2CuO4 an additional isolated excitation appears on top of the A2 g continuum.

  2. Methods for the improvement of electrical insulation in vacuum in the presence of transverse magnetic field

    International Nuclear Information System (INIS)

    Hara, Masanori; Suehiro, Junya; Shigematsu, Hidetaka; Yano, Shinsuke

    1989-01-01

    At present in electrical energy field, aiming at the development and operation of new energy sources for the future, the research on nuclear fusion reactors, MHD electricity generation, and electromagnetic energy storage is in progress, and in ordeer to form strong magnetic fields over wide space, large superconducting magnets are expected to be employed. In these magnets, when exciting current changes, voltage is induced internally, therefore, the operation sequence is deeply related to coil insulation, in pulse operation, coil insulation is one of the important factors determining the rating, and the withstand voltage design against the abnormal voltage at the time of quenching is related to the protection of coils. Therefore, the electrical insulation design of large superconducting magnets is an important subject of study. Their electrical insulation system is the compound system of liquid helium, gaseous helium, vacuum and solid insulators. When a cross magnetic field is applied, insulation breakdown characteristics are aggravated. The mechanism of vacuum insulation breakdown and characteristics, the method of improving withstand voltage using spacers or the electrodes for controlling electric field and so on are reported. (K.I.)

  3. The control of magnetism near metal-to-insulator transitions of VO2 nano-belts

    CSIR Research Space (South Africa)

    Nkosi, SS

    2016-12-01

    Full Text Available The magnetic properties of paramagnetic/weakly ferromagnetic films are strongly affected by the proximity to materials that undergo a metal to insulator phase transition. Here, we show that under the deposition conditions associated with structural...

  4. Influence of nonuniform external magnetic fields and anode--cathode shaping on magnetic insulation in coaxial transmission lines

    International Nuclear Information System (INIS)

    Mostrom, M.A.

    1979-01-01

    Coaxial transmission lines, used to transfer the high voltage pulse into the diode region of a relativistic electron beam generator, have been studied using the two-dimensional time-dependent fully relativistic and electromagnetic particle simulation code CCUBE. A simple theory of magnetic insulation that agrees well with simulation results for a straight cylindrical coax in a uniform external magnetic field is used to interpret the effects of anode--cathode shaping and nonuniform external magnetic fields. Loss of magnetic insulation appears to be minimized by satisfying two conditions: (1) the cathode surface should follow a flux surface of the external magnetic field; (2) the anode should then be shaped to insure that the magnetic insulation impedance, including transients, is always greater than the effective load impedance wherever there is an electron flow in the anode--cathode gap

  5. Superconductivity-induced magnetization depletion in a ferromagnet through an insulator in a ferromagnet-insulator-superconductor hybrid oxide heterostructure.

    Science.gov (United States)

    Prajapat, C L; Singh, Surendra; Paul, Amitesh; Bhattacharya, D; Singh, M R; Mattauch, S; Ravikumar, G; Basu, S

    2016-05-21

    Coupling between superconducting and ferromagnetic states in hybrid oxide heterostructures is presently a topic of intense research. Such a coupling is due to the leakage of the Cooper pairs into the ferromagnet. However, tunneling of the Cooper pairs though an insulator was never considered plausible. Using depth sensitive polarized neutron reflectivity we demonstrate the coupling between superconductor and magnetic layers in epitaxial La2/3Ca1/3MnO3 (LCMO)/SrTiO3/YBa2Cu3O7-δ (YBCO) hybrid heterostructures, with SrTiO3 as an intervening oxide insulator layer between the ferromagnet and the superconductor. Measurements above and below the superconducting transition temperature (TSC) of YBCO demonstrate a large modulation of magnetization in the ferromagnetic layer below the TSC of YBCO in these heterostructures. This work highlights a unique tunneling phenomenon between the epitaxial layers of an oxide superconductor (YBCO) and a magnetic layer (LCMO) through an insulating layer. Our work would inspire further investigations on the fundamental aspect of a long range order of the triplet spin-pairing in hybrid structures.

  6. Recent progress of the improved magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Fan, Yu-Wei; Zhong, Hui-Huang; Li, Zhi-Qiang; Shu, Ting; Zhang, Jian-De; Liu, Jin-Liang; Yang, Jian-Hua; Zhang, Jun; Yuan, Cheng-Wei; Luo, Ling

    2008-03-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube driven by a 550 kV, 57 kA, 50 ns electron beam. It has allowed us to generate 2.4 GW pulse of 22 ns duration. The recent progress of the improved MILO is presented in this paper. First, a field shaper cathode is introduced into the improved MILO to avoid the cathode flares in the triple point region. The experimental results show that the cathode flares are avoided, so the lifetime of the velvet cathode is longer than that of the taper cathode. Furthermore, the shot-to-shot reproducibility is better than that of the taper cathode. Second, In order to prolong the pulse duration and increase the radiated microwave power, a self-built 600 kV, 10 Omega, 80 ns pulser: SPARK-03 is employed to drive the improved MILO. Simulation and experimental investigation are performed. In simulation, when the improved MILO is driven by a 600 kV, 57 kA electron beam, high-power microwave is generated with output power of 4.15 GW, frequency of 1.76 GHz, and relevant power conversion efficiency of 12.0%. In experiments, when the diode voltage is 550 kV and current is 54 kA, the measured results are that the radiated microwave power is above 3.1 GW, the pulse duration is above 40 ns, the microwave frequency is about 1.755 GHz, and the power conversion efficiency is about 10.4%.

  7. Spectroscopic perspective on the interplay between electronic and magnetic properties of magnetically doped topological insulators

    Science.gov (United States)

    Krieger, J. A.; Chang, Cui-Zu; Husanu, M.-A.; Sostina, D.; Ernst, A.; Otrokov, M. Â. M.; Prokscha, T.; Schmitt, T.; Suter, A.; Vergniory, M. Â. G.; Chulkov, E. Â. V.; Moodera, J. S.; Strocov, V. N.; Salman, Z.

    2017-11-01

    We combine low energy muon spin rotation (LE -μ SR ) and soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) to study the magnetic and electronic properties of magnetically doped topological insulators, (Bi,Sb ) 2Te3 . We find that one achieves a full magnetic volume fraction in samples of (V/Cr ) x(Bi,Sb ) 2 -xTe3 at doping levels x ≳0.16 . The observed magnetic transition is not sharp in temperature indicating a gradual magnetic ordering. We find that the evolution of magnetic ordering is consistent with formation of ferromagnetic islands which increase in number and/or volume with decreasing temperature. Resonant ARPES at the V L3 edge reveals a nondispersing impurity band close to the Fermi level as well as V weight integrated into the host band structure. Calculations within the coherent potential approximation of the V contribution to the spectral function confirm that this impurity band is caused by V in substitutional sites. The implications of our results on the observation of the quantum anomalous Hall effect at mK temperatures are discussed.

  8. Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.L.; Chu, J.-H.; Analytis, J.G.; Liu, Z.K.; Igarashi, K.; Kuo, H.-H.; Qi, X.L.; Mo, S.K.; Moore, R.G.; Lu, D.H.; Hashimoto, M.; Sasagawa, T.; Zhang, S.C.; Fisher, I.R.; Hussain, Z.; Shen, Z.-X.; /SLAC

    2011-05-20

    Topological insulators are characterized by a massless Dirac surface state and a bulk energy gap. An insulating massive Dirac fermion state is predicted to occur if the breaking of the time reversal symmetry opens an energy gap at the Dirac point, provided that the Fermi-energy resides inside both the surface and bulk gaps. By introducing magnetic dopants into the three dimensional topological insulator Bi{sub 2}Se{sub 3} to break the time reversal symmetry, we observed the formation of a massive Dirac fermion on the surface; simultaneous magnetic and charge doping furthermore positioned the Fermi-energy inside the Dirac gap. The insulating massive Dirac Fermion state thus obtained may provide a tool for studying a range of topological phenomena relevant to both condensed matter and particle physics.

  9. Cryogenic electrical properties of irradiated cyanate ester/epoxy insulation for fusion magnets

    Science.gov (United States)

    Li, X.; Wu, Z. X.; Li, J.; Xu, D.; Liu, H. M.; Huang, R. J.; Li, L. F.

    2017-12-01

    The insulation materials used in high field fusion magnets require excellent mechanical properties, high electrical breakdown strength, good thermal conductivity and high radiation tolerance. Previous investigations showed that cyanate ester/epoxy (CE/EP) insulation material, a candidate insulation for fusion magnets, can maintain good mechanical performance at cryogenic temperature after 10 MGy irradiation and has a much longer pot life than traditional epoxy insulation material. In order to quantify the electrical properties of the CE/EP insulation material at low temperature, a cryogenic electrical property testing system cooled by a G-M cryocooler was developed for this study. An insulation material with 40% cyanate ester and 60% epoxy was subjected to 60Co γ-ray irradiation in air at ambient temperature with a dose rate of 300 Gy/min, and total doses of 1 MGy, 5 MGy and 10 MGy. The electrical breakdown strength of this CE/EP insulation material was measured before and after irradiation. The results show that cryogenic temperature has a positive effect on the electrical breakdown strength of this composite, while the influence of 60Co γ–ray irradiation is not obvious at 6.1 K.

  10. Evaluation of the Fretting Resistance of the High Voltage Insulation on the ITER Magnet Feeder Busbars

    Science.gov (United States)

    Clayton, N.; Crouchen, M.; Evans, D.; Gung, C.-Y.; Su, M.; Devred, A.; Piccin, R.

    2017-12-01

    The high voltage (HV) insulation on the ITER magnet feeder superconducting busbars and current leads will be prepared from S-glass fabric, pre-impregnated with an epoxy resin, which is interleaved with polyimide film and wrapped onto the components and cured during feeder manufacture. The insulation architecture consists of nine half-lapped layers of glass/Kapton, which is then enveloped in a ground-screen, and two further half-lapped layers of glass pre-preg for mechanical protection. The integrity of the HV insulation is critical in order to inhibit electrical arcs within the feeders. The insulation over the entire length of the HV components (bus bar, current leads and joints) must provide a level of voltage isolation of 30 kV. In operation, the insulation on ITER busbars will be subjected to high mechanical loads, arising from Lorentz forces, and in addition will be subjected to fretting erosion against stainless steel clamps, as the pulsed nature of some magnets results in longitudinal movement of the busbar. This work was aimed at assessing the wear on, and the changes in, the electrical properties of the insulation when subjected to typical ITER operating conditions. High voltage tests demonstrated that the electrical isolation of the insulation was intact after the fretting test.

  11. High pressure metallization of Mott Insulators: Magnetic, structural and electronic properties

    International Nuclear Information System (INIS)

    Pasternak, M.P.; Hearne, G.; Sterer, E.; Taylor, R.D.; Jeanloz, R.

    1993-01-01

    High pressure studies of the insulator-metal transition in the (TM)I 2 (TM = V, Fe, Co and Ni) compounds are described. Those divalent transition-metal iodides are structurally isomorphous and classified as Mott Insulators. Resistivity, X-ray diffraction and Moessbauer Spectroscopy were employed to investigate the electronic, structural, and magnetic properties as a function of pressure both on the highly correlated and on the metallic regimes

  12. Spin-Orbit Torque-Assisted Switching in Magnetic Insulator Thin Films with Perpendicular Magnetic Anisotropy

    Science.gov (United States)

    Wu, Mingzhong

    As an in-plane charge current flows in a heavy metal film with spin-orbit coupling, it produces a torque that can induce magnetization switching in a neighboring ferromagnetic metal film. Such spin-orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. This presentation reports the SOT-assisted switching in heavy metal/magnetic insulator systems.1 The experiments made use of Pt/BaFe12O19 bi-layered structures. Thanks to its strong spin-orbit coupling, Pt has been widely used to produce pure spin currents in previous studies. BaFe12O19 is an M-type barium hexagonal ferrite and is often referred as BaM. It is one of the few magnetic insulators with strong magneto-crystalline anisotropy and shows an effective uniaxial anisotropy field of about 17 kOe. It's found that the switching response in the BaM film strongly depends on the charge current applied to the Pt film. When a constant magnetic field is applied in the film plane, the charge current in the Pt film can switch the normal component of the magnetization (M⊥) in the BaM film between the up and down states. The current also dictates the up and down states of the remnant magnetization when the in-plane field is reduced to zero. When M⊥ is measured by sweeping an in-plane field, the response manifests itself as a hysteresis loop, which evolves in a completely opposite manner if the sign of the charge current is flipped. When the coercivity is measured by sweeping an out-of-plane field, its value can be reduced or increased by as much as about 500 Oe if an appropriate charge current is applied. 1. P. Li, T. Liu, H. Chang, A. Kalitsov, W. Zhang, G. Csaba, W. Li, D. Richardson, A. Demann, G. Rimal, H. Dey, J. S. Jiang, W. Porod, S. Field, J. Tang, M. C. Marconi, A. Hoffmann, O. Mryasov, and M. Wu, Nature Commun. 7:12688 doi: 10.1038/ncomms12688 (2016).

  13. Observation of the Spin Peltier Effect for Magnetic Insulators

    NARCIS (Netherlands)

    Flipse, J.; Dejene, F.K.; Wagenaar, D.; Bauer, G.E.W.; Ben Youssef, J.; Van Wees, B.J.

    2014-01-01

    We report the observation of the spin Peltier effect (SPE) in the ferrimagnetic insulator yttrium iron garnet (YIG), i.e., a heat current generated by a spin current flowing through a platinum (Pt)|YIG interface. The effect can be explained by the spin transfer torque that transforms the spin

  14. Quantized Response and Topological Magnetic Insulators with Inversion Symmetry

    NARCIS (Netherlands)

    Turner, A.M.; Zhang, Y.; Mong, R.S.K.; Vishwanath, A.

    2012-01-01

    We study three-dimensional insulators with inversion symmetry in which other point group symmetries, such as time reversal, are generically absent. We find that certain information about such materials’ behavior is determined by just the eigenvalues under inversion symmetry of occupied states at

  15. Irradiation effect of the insulating materials for fusion superconducting magnets at cryogenic temperature

    Science.gov (United States)

    Kobayashi, Koji; Akiyama, Yoko; Nishijima, Shigehiro

    2017-09-01

    In ITER, superconducting magnets should be used in such severe environment as high fluence of fast neutron, cryogenic temperature and large electromagnetic forces. Insulating material is one of the most sensitive component to radiation. So radiation resistance on mechanical properties at cryogenic temperature are required for insulating material. The purpose of this study is to evaluate irradiation effect of insulating material at cryogenic temperature by gamma-ray irradiation. Firstly, glass fiber reinforced plastic (GFRP) and hybrid composite were prepared. After irradiation at room temperature (RT) or liquid nitrogen temperature (LNT, 77 K), interlaminar shear strength (ILSS) and glass-transition temperature (Tg) measurement were conducted. It was shown that insulating materials irradiated at room temperature were much degraded than those at cryogenic temperature.

  16. Magnetic-field induced semimetal in topological crystalline insulator thin films

    International Nuclear Information System (INIS)

    Ezawa, Motohiko

    2015-01-01

    We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying opposite chirarities by applying in-plane magnetic field. A pair of gapless points have opposite vortex numbers. This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. We thus present an a magnetic-field induced semimetal–semiconductor transition in 2D material. This is a giant-magnetoresistance, where resistivity is controlled by magnetic field. Perpendicular electric field is found to shift the gapless points and also renormalize the Fermi velocity in the direction of the in-plane magnetic field. - Highlights: • The band structure of topological crystalline insulator thin films can be controlled by applying in-plane magnetic field. • At the gap closing magnetic field, a pair of gapless cones carrying opposite chirarities emerge. • A pair of gapless points have opposite vortex numbers. • This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. • A magnetic-field induced semimetal–semiconductor transition occurs in 2D material

  17. Magnetic-field induced semimetal in topological crystalline insulator thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ezawa, Motohiko, E-mail: ezawa@ap.t.u-tokyo.ac.jp

    2015-06-19

    We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying opposite chirarities by applying in-plane magnetic field. A pair of gapless points have opposite vortex numbers. This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. We thus present an a magnetic-field induced semimetal–semiconductor transition in 2D material. This is a giant-magnetoresistance, where resistivity is controlled by magnetic field. Perpendicular electric field is found to shift the gapless points and also renormalize the Fermi velocity in the direction of the in-plane magnetic field. - Highlights: • The band structure of topological crystalline insulator thin films can be controlled by applying in-plane magnetic field. • At the gap closing magnetic field, a pair of gapless cones carrying opposite chirarities emerge. • A pair of gapless points have opposite vortex numbers. • This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. • A magnetic-field induced semimetal–semiconductor transition occurs in 2D material.

  18. RADLAC II/SMILE performance with a magnetically insulated voltage adder

    International Nuclear Information System (INIS)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Crist, C.E.; Poukey, J.W.; Prestwich, K.R.; Turman, B.N.; Struve, K.; Welch, D.

    1991-01-01

    A 12.5-m long Self Magnetically Insulate Transmission LinE (SMILE) that sums the voltages of 8, 2 -MV pulse forming lines was installed in the RADLAC-II linear induction accelerator. The magnetic insulation criteria was calculated using parapotential flow theory and found to agree with MAGIC simulations. High quality annular beams with β perpendicular ≤ 0.1 and a radius r b < 2 cm were measured for currents of 50-100-kA extracted from a magnetic immersed foilless diode. These parameters were achieved with 11 to 15-MV accelerating voltages and 6 to 16-kG diode magnetic field. The experimental results exceeded the design expectations and are in good agreement with code simulations

  19. RADLAC II/SMILE performance with a magnetically insulated voltage adder

    Energy Technology Data Exchange (ETDEWEB)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Crist, C.E.; Poukey, J.W.; Prestwich, K.R.; Turman, B.N. (Sandia National Labs., Albuquerque, NM (USA)); Struve, K.; Welch, D. (Mission Research Corp., Albuquerque, NM (USA))

    1991-01-01

    A 12.5-m long Self Magnetically Insulated Transmission LinE (SMILE) that sums the voltages of 8, 2-MV pulse forming lines was installed in the RADLAC-II linear induction accelerator. The magnetic insulation criteria was calculated using parapotential flow theory and found to agree with MAGIC simulations. High quality annular beams with {beta}{perpendicular} {le} 0.1 and a radius r{sub b} < 2 cm were measured for currents of 50--100-kA extracted from a magnetic immersed foilless diode. These parameters were achieved with 11 to 15-MV accelerating voltages and 6 to 16-kG diode magnetic field. The experimental results exceeded our design expectations and are in good agreement with code simulations. 6 refs., 6 figs., 1 tab.

  20. Organic insulators and the copper stabilizer for fusion-reactor magnets

    International Nuclear Information System (INIS)

    Coltman, R.R. Jr.

    1981-11-01

    The materials which compose the large composite superconducting fusion reactor magnets are subjected to mechanical stress, neutron and gamma-ray radiation with broad energy spectra, high magnetic fields, and thermal cycling from 4 to 300 K. Of the materials now considered for use in the magnets, results show that the organic insulators and the Cu stabilizer are the most sensitive to this environment. In response to the need for stabilizer data, magnetoresistivity changes were studied in eight variously prepared specimens of Cu throughout five cycles of an alternate neutron irradiation (4.0 K) and annealing (14 h at 307 K) program. The results were combined with those on the radiation behavior of epoxy and polyimide organic insulators to provide a preliminary assessment of their comparative radiation resistance in a typical magnet location of the Experimental Power Reactor

  1. Simulation study of magnetically insulated power coupling to the applied-B ion diode

    International Nuclear Information System (INIS)

    Rosenthal, S.E.

    1992-01-01

    Power coupling to the applied-B ion diode from magnetically insulated transmission lines is simply described in terms of the voltage-current characteristics of both the diode and the transmission line. The accelerator load line intersects the composite characteristic at the operating voltage and current. Using 2-D PIC simulation, the authors have investigated how modification of either the ion diode or the magnetically insulated transmission line characteristic influences power coupling. Plasma prefill can modify the ion diode characteristic; a partially opened POS in the transmission line upstream of the ion diode is a possible cause of modification of the magnetically insulated transmission line characteristic. It can be useful to consider these two aspects of power coupling separately, but they are actually not independent. A good parameter to characterize the situation is the flow impedance, given by V/(I a 2 I c 2 ) 1/2 . V is the line voltage; I a and I c are the conduction currents flowing through the anode and cathode, respectively. The flow impedance covers a range from one half the vacuum impedance, for saturated magnetically insulated flow, to just below the vacuum impedance, for highly unsaturated flow. As the term ''flow impedance'' implies, low flow impedance coincides with greater electron flow while high flow impedance coincides with less electron flow. The flow impedance is sensitive to both the transmission line and the diode impedance. They show how the two are related, using the flow impedance as a parameter

  2. The polyimide-alumina: a performant insulator used in a superconducting magnet cooled with superfluid helium

    International Nuclear Information System (INIS)

    Libeyre, M.

    1987-03-01

    Thermal insulation between the coils of the toroidal magnet of Tore Supra and the ''box'' including it able to transmit mechanical efforts is necessary. To require to the specifications a new material has been developed; industrial production of this material has also been realized [fr

  3. Reduction of angular spread at nonadiabatic electron motion in magnetically insulated diode

    International Nuclear Information System (INIS)

    Arzhannikov, A.V.; Sinitskij, S.L.

    1996-01-01

    The behavior of the electron pitch-angle was investigated by analytical and numerical methods for the case of a magnetically insulated diode with a ribbon geometry. It is shown that at the boundary of the adiabaticity of the electron motion the angle can be multiply reduced by choice of a special inhomogeneity of the magnetic field. Analytic expressions for the final pitch-angle of the beam electrons are given. (author). 2 figs., 3 refs

  4. Helium II heat transfer in LHC magnets : polyimide cable insulation

    NARCIS (Netherlands)

    Winkler, Tiemo

    2017-01-01

    Today’s large particle accelerators like the LHC at CERN are using superconducting materials as a construction material for magnets. These magnets need to be cooled constantly to temperatures below the critical surface of the superconducting material. In the LHC this is achieved by using liquid

  5. Dressed topological insulators. Rashba impurity, Kondo effect, magnetic impurities, proximity-induced superconductivity, hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Posske, Thore Hagen

    2016-02-26

    Topological insulators are electronic phases that insulate in the bulk and accommodate a peculiar, metallic edge liquid with a spin-dependent dispersion. They are regarded to be of considerable future use in spintronics and for quantum computation. Besides determining the intrinsic properties of this rather novel electronic phase, considering its combination with well-known physical systems can generate genuinely new physics. In this thesis, we report on such combinations including topological insulators. Specifically, we analyze an attached Rashba impurity, a Kondo dot in the two channel setup, magnetic impurities on the surface of a strong three-dimensional topological insulator, the proximity coupling of the latter system to a superconductor, and hybrid systems consisting of a topological insulator and a semimetal. Let us summarize our primary results. Firstly, we determine an analytical formula for the Kondo cloud and describe its possible detection in current correlations far away from the Kondo region. We thereby rely on and extend the method of refermionizable points. Furthermore, we find a class of gapless topological superconductors and semimetals, which accommodate edge states that behave similarly to the ones of globally gapped topological phases. Unexpectedly, we also find edge states that change their chirality when affected by sufficiently strong disorder. We regard the presented research helpful in future classifications and applications of systems containing topological insulators, of which we propose some examples.

  6. Optical magnetism and plasmonic Fano resonances in metal-insulator-metal oligomers.

    Science.gov (United States)

    Verre, R; Yang, Z J; Shegai, T; Käll, M

    2015-03-11

    The possibility of achieving optical magnetism at visible frequencies using plasmonic nanostructures has recently been a subject of great interest. The concept is based on designing structures that support plasmon modes with electron oscillation patterns that imitate current loops, that is, magnetic dipoles. However, the magnetic resonances are typically spectrally narrow, thereby limiting their applicability in, for example, metamaterial designs. We show that a significantly broader magnetic response can be realized in plasmonic pentamers constructed from metal-insulator-metal (MIM) sandwich particles. Each MIM unit acts as a magnetic meta-atom and the optical magnetism is rendered quasi-broadband through hybridization of the in-plane modes. We demonstrate that scattering spectra of individual MIM pentamers exhibit multiple Fano resonances and a broad subradiant spectral window that signals the magnetic interaction and a hierarchy of coupling effects in these intricate three-dimensional nanoparticle oligomers.

  7. Metallic Interface Emerging at Magnetic Domain Wall of Antiferromagnetic Insulator: Fate of Extinct Weyl Electrons

    Directory of Open Access Journals (Sweden)

    Youhei Yamaji

    2014-05-01

    Full Text Available Topological insulators, in contrast to ordinary semiconductors, accompany protected metallic surfaces described by Dirac-type fermions. Here, we theoretically show that another emergent two-dimensional metal embedded in the bulk insulator is realized at a magnetic domain wall. The domain wall has long been studied as an ingredient of both old-fashioned and leading-edge spintronics. The domain wall here, as an interface of seemingly trivial antiferromagnetic insulators, emergently realizes a functional interface preserved by zero modes with robust two-dimensional Fermi surfaces, where pyrochlore iridium oxides proposed to host the condensed-matter realization of Weyl fermions offer such examples at low temperatures. The existence of in-gap states that are pinned at domain walls, theoretically resembling spin or charge solitons in polyacetylene, and protected as the edges of hidden one-dimensional weak Chern insulators characterized by a zero-dimensional class-A topological invariant, solves experimental puzzles observed in R_{2}Ir_{2}O_{7} with rare-earth elements R. The domain wall realizes a novel quantum confinement of electrons and embosses a net uniform magnetization that enables magnetic control of electronic interface transports beyond the semiconductor paradigm.

  8. Interplay of Dirac surface states and magnetic fluctuations in topological insulator heterostructures

    Science.gov (United States)

    Hurst, Hilary M.; Efimkin, Dmitry K.; Galitski, Victor

    We consider the proximity effect between Dirac states at the surface of a topological insulator and a ferromagnet with easy plane anisotropy, which is described by the XY-model and undergoes a Berezinskii-Kosterlitz-Thouless (BKT) phase transition. Classical magnetic fluctuations interacting with the surface states of a topological insulator can be described by an effective gauge field. This model can be mapped onto the problem of Dirac fermions in a random magnetic field, however this analogy is only partial in the presence of electron-hole asymmetry or warping of the Dirac dispersion which results in screening of magnetic fluctuations. We show that this proximity coupling leads to anomalous transport behavior of the surface states near the BKT transition temperature.

  9. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    Science.gov (United States)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  10. Systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators

    Science.gov (United States)

    Grisham, Larry R

    2013-12-17

    The present invention provides systems and methods for the magnetic insulation of accelerator electrodes in electrostatic accelerators. Advantageously, the systems and methods of the present invention improve the practically obtainable performance of these electrostatic accelerators by addressing, among other things, voltage holding problems and conditioning issues. The problems and issues are addressed by flowing electric currents along these accelerator electrodes to produce magnetic fields that envelope the accelerator electrodes and their support structures, so as to prevent very low energy electrons from leaving the surfaces of the accelerator electrodes and subsequently picking up energy from the surrounding electric field. In various applications, this magnetic insulation must only produce modest gains in voltage holding capability to represent a significant achievement.

  11. Mott-insulating phases and magnetism of fermions in a double-well optical lattice

    International Nuclear Information System (INIS)

    Wang, Xin; Zhou, Qi; Das Sarma, S.

    2011-01-01

    We theoretically investigate, using nonperturbative strong correlation techniques, Mott-insulating phases and magnetic ordering of two-component fermions in a two-dimensional double-well optical lattice. At filling of two fermions per site, there are two types of Mott insulators, one of which is characterized by spin-1 antiferromagnetism below the Neel temperature. The superexchange interaction in this system is induced by the interplay between the interband interaction and the spin degree of freedom. A great advantage of the double-well optical lattice is that the magnetic quantum phase diagram and the Neel temperature can be easily controlled by tuning the orbital energy splitting of the two-level system. Particularly, the Neel temperature can be one order of magnitude larger than that in standard optical lattices, facilitating the experimental search for magnetic ordering in optical lattice systems.

  12. Anisotropic exchange interaction for magnetic ion pairs in insulators

    International Nuclear Information System (INIS)

    Passeggi, M.C.G.

    1975-12-01

    The sources of possible contributions to the magnetic anisotropy for a pair of orbitally non degenerate magnetic ions are investigated. The problem being formulated with the help of the operator form of perturbation theory and irreducible tensor operators. Apart from the usual dipole-dipole effective interaction, mainly induced by the electronic spin-spin dipole coupling corrected by covalency, other mechanisms mediated by the spin-orbit coupling appear. These are a consequence of an appropriate description of the spin-orbit operators for a system which allows for delocalization of the magnetic electrons. A process similar to that known as pseudodipolar appears from contributions in which spin orbit combined with the Coulomb repulsion and with one-electron interactions (acting analogously as for the ''kinetic exchange'') produce compensating effects in third and fourth order, respectively. However, this effect does not appear to be describable in terms of the phenomenological exchange, as is usually assumed. (Passeggi, M.C.G.)

  13. Magnetic ordering at low temperatures in some random superconducting and insulating compounds

    International Nuclear Information System (INIS)

    Hueser, D.

    1985-01-01

    This thesis presents the results of some investigations on the magnetic ordering phenomena in some random superconducting and insulating materials. The results are described of an investigation of the coexistence of superconductivity and random magnetic freezing in (Th,Nd)Ru 2 . On the basis of various measurements as function of temperature and external magnetic field the author found that spin glass-like freezing can occur far below the superconductivity and even that a sample may re-enter the superconducting state below a freezing temperature. Associated with the isothermal remanent magnetization of a random magnetic material he observed strong anomalies in the critical field versus temperature curves. Also a magnetic field memory effect has been found. (Auth.)

  14. Effects of magnetic impurities on transport in 2D topological insulators

    Science.gov (United States)

    Dang, Xiaoqian; Burton, J. D.; Tsymbal, Evgeny

    Understanding the transport properties of topological insulators could bring such materials from fundamental research to potential applications. Here we report on the theoretical investigations of the effects of magnetic impurities on transport properties of model two-dimensional (2D) topological insulators (TIs). We utilize the tight-binding form of the Bernevig-Hughes-Zhang model and investigate the transport properties by employing the Landauer-Büttiker formalism. We explore the current distribution in 2D TIs resulting from scattering by a magnetic impurity which breaks time-reversal symmetry. We find that a magnetic impurity could drive anti-resonant behavior of the conductance, as revealed from full backscattering of the electron current flowing at one of the edges of the TI. This phenomenon occurs due to spin-flip scattering when the Fermi energy matches the impurity state and the magnetic moment of the impurity is aligned along the TI edge. Additionally, we explore the effect of an external magnetic gate attached to the system and show that changing the magnetization orientation within the gate allows the control of conductance. This geometric setup could be realized experimentally providing the opportunity to tune transport properties of 2D TIs by a magnetic gate.

  15. Asymmetric d-wave superconducting topological insulator in proximity with a magnetic order

    Science.gov (United States)

    Khezerlou, M.; Goudarzi, H.; Asgarifar, S.

    2018-02-01

    In the framework of the Dirac-Bogoliubov-de Gennes formalism, we investigate the transport properties in the surface of a 3-dimensional topological insulator-based hybrid structure, where the ferromagnetic and superconducting orders are simultaneously induced to the surface states via the proximity effect. The superconductor gap is taken to be spin-singlet d-wave symmetry. The asymmetric role of this gap respect to the electron-hole exchange, in one hand, affects the topological insulator superconducting binding excitations and, on the other hand, gives rise to forming distinct Majorana bound states at the ferromagnet/superconductor interface. We propose a topological insulator N/F/FS junction and proceed to clarify the role of d-wave asymmetry pairing in the resulting subgap and overgap tunneling conductance. The perpendicular component of magnetizations in F and FS regions can be at the parallel and antiparallel configurations leading to capture the experimentally important magnetoresistance (MR) of junction. It is found that the zero-bias conductance is strongly sensitive to the magnitude of magnetization in FS region mzfs and orbital rotated angle α of superconductor gap. The negative MR only occurs in zero orbital rotated angle. This result can pave the way to distinguish the unconventional superconducting state in the relating topological insulator hybrid structures.

  16. Magnetic correlations and quantum criticality in the insulating antiferromagnetic, insulating spin liquid, renormalized Fermi liquid, and metallic antiferromagnetic phases of the Mott system V2O3

    Science.gov (United States)

    Bao, Wei; Broholm, C.; Aeppli, G.; Carter, S. A.; Dai, P.; Rosenbaum, T. F.; Honig, J. M.; Metcalf, P.; Trevino, S. F.

    1998-11-01

    Magnetic correlations in all four phases of pure and doped vanadium sesquioxide (V2O3) have been examined by magnetic thermal-neutron scattering. Specifically, we have studied the antiferromagnetic and paramagnetic phases of metallic V2-yO3, the antiferromagnetic insulating and paramagnetic metallic phases of stoichiometric V2O3, and the antiferromagnetic and paramagnetic phases of insulating V1.944Cr0.056O3. While the antiferromagnetic insulator can be accounted for by a localized Heisenberg spin model, the long-range order in the antiferromagnetic metal is an incommensurate spin-density wave, resulting from a Fermi surface nesting instability. Spin dynamics in the strongly correlated metal are dominated by spin fluctuations with a ``single lobe'' spectrum in the Stoner electron-hole continuum. Furthermore, our results in metallic V2O3 represent an unprecedentedly complete characterization of the spin fluctuations near a metallic quantum critical point, and provide quantitative support for the self-consistent renormalization theory for itinerant antiferromagnets in the small moment limit. Dynamic magnetic correlations for ħωinsulator carry substantial magnetic spectral weight. However, they are extremely short-ranged, extending only to the nearest neighbors. The phase transition to the antiferromagnetic insulator, from the paramagnetic metal and the paramagnetic insulator, introduces a sudden switching of magnetic correlations to a different spatial periodicity which indicates a sudden change in the underlying spin Hamiltonian. To describe this phase transition and also the unusual short-range order in the paramagnetic state, it seems necessary to take into account the orbital degrees of freedom associated with the degenerate d orbitals at the Fermi level in V2O3.

  17. Simulation of magnetic tunnel junction in ferromagnetic/insulator/semiconductor structure

    Science.gov (United States)

    Kostrov, Alexander I.; Stempitsky, Viktor R.; Kazimirchik, Vladimir N.

    2008-07-01

    In this work, we present a physical model and electrical macromodel for simulation of Magnetic Tunnel Junction (MTJ) effect based on Ferromagnetic/Insulator/Semiconductor (FIS) nanostructure. A modified Brinkman model has been proposed by including the voltage-dependent density of states of the ferromagnetic electrodes in order to explain the bias dependence magnitoresistance. The model takes into account injection of carriers in the semiconductor and Shottky barrier, electron tunneling through thin insulator and spin-transfer torque writing approach in memory cell. These very promising features should constitute the third generation of Magnetoresistive RAM (MRAM). Besides, the model can efficiently be used to design magnetic CMOS circuits. The behavioral macro-model has been developed by means of Verilog-AMS language and implemented on the Cadence Virtuoso platform with Spectre simulator.

  18. Rippled disc electrostatic generator/motor configurations utilizing magnetic insulation

    Science.gov (United States)

    Post, Richard F

    2017-04-04

    Electrostatic generators/motors designs are provided that generally may include a first rippled stator centered about a longitudinal axis; a second rippled stator centered about the axis, a first rippled rotor centered about the axis and located between the first rippled stator and the second rippled stator. A magnetic field having field lines about parallel with the average plane of at least one of the first rippled stator or the second rippled stator is provided with either a Halbach array configuration or a conductor array configuration.

  19. Proximity Effect Induced Spin Injection in Phosphorene on Magnetic Insulator.

    Science.gov (United States)

    Chen, Haoqi; Li, Bin; Yang, Jinlong

    2017-11-08

    Black phosphorus is a promising candidate for future nanoelectronics with a moderate electronic band gap and a high carrier mobility. Introducing the magnetism into black phosphorus will widely expand its application scope and may present a bright prospect in spintronic nanodevices. Here, we report our first-principles calculations of spin-polarized electronic structure of monolayer black phosphorus (phosphorene) adsorbed on a magnetic europium oxide (EuO) substrate. Effective spin injection into the phosphorene is realized by means of interaction with the nearby EuO(111) surface, i.e., proximity effect, which results in spin-polarized electrons in the 3p orbitals of phosphorene, with the spin polarization at Fermi level beyond 30%, together with an exchange-splitting energy of ∼0.184 eV for conduction-band minimum of the adsorbed phosphorene corresponding to an energy region where only one spin channel is conductive. The energy region of these exchange-splitting and spin-polarized band gaps of the adsorbed phosphorene can be effectively modulated by in-plane strain. Intrinsically high and anisotropic carrier mobilities at the conduction-band minimum of the phosphorene also become spin-polarized mainly due to spin polarization of deformation potentials and are not depressed significantly after the adsorption. These extraordinary properties would endow black phosphorus with great potentials in the future spintronic nanodevices.

  20. Mechanical engineering and design criteria for the Magnetically Insulated Transmission Experiment Accelerator

    International Nuclear Information System (INIS)

    Staller, G.E.; Hamilton, I.D.; Aker, M.F.; Fifer, H.G.

    1978-02-01

    A single-unit electron beam accelerator was designed, fabricated, and assembled in Sandia's Technical Area V to conduct magnetically insulated transmission experiments. Results of these experiments will be utilized in the future design of larger, more complex accelerators. This design makes optimum use of existing facilities and equipment. When designing new components, possible future applications were considered as well as compatibility with existing facilities and hardware

  1. Tuning the metal-insulator transition in manganite films through surface exchange coupling with magnetic nanodots.

    Science.gov (United States)

    Ward, T Z; Gai, Z; Xu, X Y; Guo, H W; Yin, L F; Shen, J

    2011-04-15

    In strongly correlated electronic systems, the global transport behavior depends sensitively on spin ordering. We show that spin ordering in manganites can be controlled by depositing isolated ferromagnetic nanodots at the surface. The exchange field at the interface is tunable with nanodot density and makes it possible to overcome dimensionality and strain effects in frustrated systems to greatly increasing the metal-insulator transition and magnetoresistance. These findings indicate that electronic phase separation can be controlled by the presence of magnetic nanodots.

  2. Physics Colloquium: Theory of the spin wave Seebeck effect in magnetic insulators

    CERN Multimedia

    Université de Genève

    2011-01-01

    Geneva University Physics Department 24, quai Ernest-Ansermet CH-1211 Geneva 4 Lundi 28 février 2011 17h00 - École de Physique, Auditoire Stückelberg Theory of the spin wave Seebeck effect in magnetic insulators Prof. Gerrit Bauer Delft University of Technology The subfield of spin caloritronics addresses the coupling of heat, charge and spin currents in nanostructures. In the center of interest is here the spin Seebeck effect, which was discovered in an iron-nickel alloy. Uchida et al. recently observed the effect also in an electrically insulating Yttrium Iron Garnett (YIG) thin magnetic film. To our knowledge this is the first observation of a Seebeck effect generated by an insulator, implying that the physics is fundamentally different from the conventional Seebeck effect in metals. We explain the experiments by the pumping of a spin current into the detecting contacts by the thermally excited magnetization dynamics. In this talk I will give a brief overview over the state o...

  3. Equilibrium of a high current electron beam of the THETA-pinch type in ap inverse coaxial magnetically insulated diode

    International Nuclear Information System (INIS)

    Agafonov, A.V.

    1982-01-01

    A possibility of uSing inverse coaxial magnetically insulated diodes for creating megagauss magnetic fields is discussed. In an inverse diode placed in an external magnetic field the beam behaves like a diamagnetic displacing the magnetic field inwards by the radius. It is shown that at the diode voltage approximately 10 MV ana anode-cathode radii relation < or aaproximately 0.1 magnetic fields approximately 1-10 MGs may be obtained

  4. Radiation hardness of superconducting magnet insulation materials for FAIR

    International Nuclear Information System (INIS)

    Seidl, Tim

    2013-03-01

    This thesis focuses on radiation degradation studies of polyimide, polyepoxy/glass-fiber composites and other technical components used, for example, in the superconducting magnets of new ion accelerators such as the planned International Facility for Antiproton and Ion Research (FAIR) at the GSI Helmholtz Center of Heavy Ion Research (GSI) in Darmstadt. As accelerators are becoming more powerful, i.e., providing larger energies and beam intensities, the potential risk of radiation damage to the components increases. Reliable data of the radiation hardness of accelerator materials and components concerning electrical, thermal and other technical relevant properties are of great interest also for other facilities such as the Large Hadron Collider (LHC) of CERN. Dependent on the position of the different components, induced radiation due to beam losses consists of a cocktail of gammas, neutrons, protons, and heavier particles. Although the number of heavy fragments of the initial projectiles is small compared to neutrons, protons, or light fragments (e.g. ? particles), their large energy deposition can induce extensive damage at rather low fluences (dose calculations show that the contribution of heavy ions to the total accumulated dose can reach 80 %). For this reason, defined radiation experiments were conducted using different energetic ion beams (from protons to uranium) and gamma radiation from a Co-60 source. The induced changes were analyzed by means of in-situ and ex-situ analytical methods, e.g. ultraviolet-visible and infrared spectroscopy, residual gas analysis, thermal gravimetric analysis, dielectric strength measurements, measurements of low temperature thermal properties, and performance tests. In all cases, the radiation induces a change in molecular structure as well as loss of functional material properties. The amount of radiation damage is found to be sensitive to the used type of ionizing radiation and the long term stability of the materials is

  5. TPX superconducting Tokamak magnet system: 1995 design and status overview

    International Nuclear Information System (INIS)

    Deis, G.; Bulmer, R.; Carpenter, R.

    1995-01-01

    The TPX magnet preliminary design effort is summarized. Key results and accomplishments during preliminary design and supporting R and D are discussed, including conductor development, quench detection, TF and PF magnet design, conductor bending and forming, reaction heat treating, helium stubs, and winding pack insulation

  6. A new cable-in-conduit conductor magnet with insulated strands

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, Satarou; Yamamoto, Junya; Motojima, Osamu

    1995-09-01

    Many studies have used cable-in-conduit conductor (CICC) coils in trying to develop an AC superconducting magnet because of its enormous potential if AC losses were low and insulation voltage was high. The strands in the most recent CICC magnets are coated with chromium or another metal with high electrical resistance to order to induce current re-distribution among the strands and to avoid a quench caused by a current imbalance. Current re-distribution is highly complex and very difficult to analyze because the conditions of the strand surfaces and the contact areas vary greatly with the operation of the conductor. If, however, the cable currents were well-balanced, insulating the strands would be the best way to reduce AC losses. We propose a new CICC magnet structure featuring a current lead that balances the strand currents via its resistance. Having calculated current balances, we find that strand currents are well within the present parameters for nuclear fusion experiments and superconducting magnet energy storages. (author).

  7. A new cable-in-conduit conductor magnet with insulated strands

    International Nuclear Information System (INIS)

    Yamaguchi, Satarou; Yamamoto, Junya; Motojima, Osamu.

    1995-09-01

    Many studies have used cable-in-conduit conductor (CICC) coils in trying to develop an AC superconducting magnet because of its enormous potential if AC losses were low and insulation voltage was high. The strands in the most recent CICC magnets are coated with chromium or another metal with high electrical resistance to order to induce current re-distribution among the strands and to avoid a quench caused by a current imbalance. Current re-distribution is highly complex and very difficult to analyze because the conditions of the strand surfaces and the contact areas vary greatly with the operation of the conductor. If, however, the cable currents were well-balanced, insulating the strands would be the best way to reduce AC losses. We propose a new CICC magnet structure featuring a current lead that balances the strand currents via its resistance. Having calculated current balances, we find that strand currents are well within the present parameters for nuclear fusion experiments and superconducting magnet energy storages. (author)

  8. Complete mode-set stability analysis of magnetically insulated ion diode equilibria

    International Nuclear Information System (INIS)

    Slutz, S.A.; Lemke, R.W.

    1993-01-01

    We present the first analysis of the stability of magnetically insulated ion diodes that is fully relativistic and includes electromagnetic perturbations both parallel and perpendicular to the applied magnetic field. Applying this formalism to a simple diode equilibrium model that neglects velocity shear and density gradients, we find a fast growing mode that has all of the important attributes of the low frequency mode observed in numerical simulations of magnetically insulated ion diodes, which may be a major cause of ion divergence. We identify this mode as a modified two-stream instability. Previous stability analyses indicate a variety of unstable modes, but none of these exhibit the same behavior as the low frequency mode observed in the simulations. In addition, we analyze a realistic diode equilibrium model that includes velocity shear and an electron density profile consistent with that observed in the numerical simulations. We find that the diocotron instability is reduced, but not fully quenched by the extension of the electron sheath to the anode. However, the inclusion of perturbations parallel to the applied magnetic field with a wavelength smaller than the diode height does eliminate growth of this instability. This may explain why the diocotron mode has been observed experimentally with proton sources, but not with LiF, since the turn on of LiF is not uniform

  9. Spin and Charge Transport in 2D Materials and Magnetic Insulator/Metal Heterostructures

    Science.gov (United States)

    Amamou, Walid

    Spintronic devices are very promising for future information storage, logic operations and computation and have the potential to replace current CMOS technology approaching the scaling limit. In particular, the generation and manipulation of spin current enables the integration of storage and logic within the same circuit for more powerful computing architectures. In this thesis, we examine the manipulation of spins in 2D materials such as graphene and metal/magnetic insulator heterostructures. In particular, we investigate the feasibility for achieving magnetization switching of a nanomagnet using graphene as a nonmagnetic channel material for All Spin Logic Device applications. Using in-situ MBE deposition of nanomagnet on graphene spin valve, we demonstrate the presence of an interfacial spin dephasing at the interface between the graphene and the nanomagnet. By introducing a Cu spacer between the nanomagnet and graphene, we demonstrate that this interfacial effect is related to an exchange interaction between the spin current and the disordered magnetic moment of the nanomagnet in the first monolayer. In addition to the newly discovered interfacial spin relaxation effect, the extracted contact resistance area product of the nanomagnet/graphene interface is relatively high on the order of 1Omicrom2. In practice, reducing the contact resistance will be as important as eliminating the interfacial relaxation in order to achieve magnetization switching. Furthermore, we examine spin manipulation in a nonmagnetic Pt using an internal magnetic exchange field produced by the adjacent magnetic insulator CoFe2O4 grown by MBE. Here, we report the observation of a strong magnetic proximity effect of Pt deposited on top of a perpendicular magnetic anisotropy (PMA) inverse spinel material Cobalt Ferrite (CFO, CoFe 2O4). The CFO was grown by MBE and its magnetization was characterized by Vibrating Sample Magnetometry (VSM) demonstrating the strong out of plane magnetic

  10. Quantum capacitance of an ultrathin topological insulator film in a magnetic field

    KAUST Repository

    Tahir, M.

    2013-02-12

    We present a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field. The study is undertaken to investigate the interplay of the Zeeman interaction with the hybridization between the upper and lower surfaces of the thin film. Determining the density of states, we find that the electron-hole symmetry is broken when the Zeeman and hybridization energies are varied relative to each other. This leads to a change in the character of the magnetocapacitance at the charge neutrality point. We further show that in the presence of both Zeeman interaction and hybridization the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high perpendicular magnetic field. In addition, we address the crossover from perpendicular to parallel magnetic field and find consistency with recent experimental data.

  11. Metal-Insulator transition at very high magnetic fields in an organic conductor

    Science.gov (United States)

    Graf, D.; Choi, E. S.; Brooks, J. S.; Mielke, C.; Harrison, N.; Murata, K.; Konoike, T.; Papavassiliou, G. C.

    2003-03-01

    Tau-phase organic conductors based on the P-(S,S)-DMEDT-TTF donor molecule exhibit a first order phase transition in high magnetic fields. Low temperature magnetoresistance measurements of τ-(P-(S,S)-DMEDT-TTF)_2(AuBr_2)_1_+y show an abrupt upturn when fields are swept beyond 35 tesla. Observations of sample current indicate that conduction ceases completely in the insulating state. Skin depth, magnetocaloric, and magnetization measurements in pulsed magnetic fields were also used to characterize the high field phase diagram of this metal-insulator transition. Measurements of the angular dependence reveal this to be an isotropic bulk effect rather than an orbital effect in stark contrast to conventional low dimensional metals. In contrast, τ-(EDO-(S,S)-DMEDT-TTF)_2(AuBr_2)_1_+y exhibits pronounced SdH oscillations against a less pronounced, but isotropic rise in magnetoresistance. Models for this new type of transition in an organic conductor will be considered.

  12. FLOWTRAN-TF code benchmarking

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G.P. (ed.)

    1990-12-01

    FLOWTRAN-TF is a two-component (air-water), two-phase thermal-hydraulics code designed for performing accident analyses of SRS reactor fuel assemblies during the Emergency Cooling System (ECS) phase of a Double Ended Guillotine Break (DEGB) Loss Of Coolant Accident (LOCA). A description of the code is given by Flach et al. (1990). This report provides benchmarking results for the version of FLOWTRAN-TF used to compute the Recommended K-Reactor Restart ECS Power Limit (Smith et al., 1990a; 1990b). Individual constitutive relations are benchmarked in Sections 2 through 5 while in Sections 6 and 7 integral code benchmarking results are presented. An overall assessment of FLOWTRAN-TF for its intended use in computing the ECS power limit completes the document.

  13. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    KAUST Repository

    Tahir, M.

    2012-12-06

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  14. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    Science.gov (United States)

    Tahir, M.; Schwingenschlögl, U.

    2012-12-01

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  15. Analysis of NSTX TF Joint Voltage Measurements

    International Nuclear Information System (INIS)

    Woolley R

    2005-01-01

    This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''

  16. Investigation of cryogenic irradiation influence on mechanical and physical properties of ITER magnetic system insulation materials

    International Nuclear Information System (INIS)

    Kozlov, A.V.; Scherbacov, E.N.; Dudchenko, N.A.; Shihalev, V.S.; Bedin, V.V.; Paltusov, N.A.; Korsunskiy, V.E.

    1998-01-01

    A set of methods of cryogenic irradiation influence test on mechanical and physical properties of insulation of ITER magnetic system are presented in this paper. Investigations are carried out without intermediate warming up of samples. A Russian insulating composite material was irradiated in the IVV-2M reactor. The ratio of energy absorbed by insulation materials from neutron irradiation to that from gamma irradiation can be varied from ∝(25:75)% to ∝(50:50)% in the reactor. The test results on the thermal expansion, thermal conductivity and gas evolution of the above material are presented. It was shown, that cryogenic irradiation up to the fluence ∝2 x 10 22 n/m 2 (E ≥ 0.1 MeV) leads to 0.27% linear size changes along layers of fiber-glass, the thermal conductivity coefficient is decreased on 15% at 100 k in perpendicular direction to fiber-glass plane, and thermal coefficient of linear expansion (TCLE) has anomalous temperature dependence. (orig.)

  17. FLOWTRAN-TF user guide

    Energy Technology Data Exchange (ETDEWEB)

    Flach, G.P.; Lee, S.Y.; Aleman, S.E.

    1993-02-01

    This document is a set of detailed instructions and guidelines to aid users in constructing and interpreting FLOWTRAN-TF input and output files for version 1.2 of the source code. The document assumes the user is familiar with the FLOWTRAN-TF Software Design report, SRS fuel assembly hardware, and two-phase flow. General code capabilities and input options are summarized. Then, detailed instructions for creating and interpreting code input files are given next. A sample input deck and corresponding output files are listed for reference and illustration. FLOWTRAN-TF is a two-phase thermal-hydraulics code of similar technology to existing commercial reactor codes such as RELAP and TRAC but customized for Savannah River Site applications. The code may be used to simulate solid components, fluid coolant flow and solid-fluid heat transfer, or fluid flow only (adiabatic flow channels). Pure component water or two-component air-water flows may be modeled. A variety of materials may be chosen for the solid tubes separating flow channels. FLOWTRAN-TF is fundamentally a transient analysis tool.

  18. Metal-insulator crossover in superconducting cuprates in strong magnetic fields

    International Nuclear Information System (INIS)

    Marchetti, P.A.; Su Zhaobin; Yu Lu

    2001-02-01

    The metal-insulator crossover of the in-plane resistivity upon temperature decrease, recently observed in several classes of cuprate superconductors, when a strong magnetic field suppresses the superconductivity, is explained using the U(1)xSU(2) Chern-Simons gauge field theory. The origin of this crossover is the same as that for a similar phenomenon observed in heavily underdoped cuprates without magnetic field. It is due to the interplay between the diffusive motion of the charge carriers and the 'peculiar' localization effect due to short-range antiferromagnetic order. We also calculate the in-plane transverse magnetoresistance which is in a fairly good agreement with available experimental data. (author)

  19. Strain and Thermally Induced Magnetic Dynamics and Spin Current in Magnetic Insulators Subject to Transient Optical Grating

    Directory of Open Access Journals (Sweden)

    Xi-Guang Wang

    2017-07-01

    Full Text Available We analyze the magnetic dynamics and particularly the spin current in an open-circuit ferromagnetic insulator irradiated by two intense, phase-locked laser pulses. The interference of the laser beams generates a transient optical grating and a transient spatiotemporal temperature distribution. Both effects lead to elastic and heat waves at the surface and into the bulk of the sample. The strain induced spin current as well as the thermally induced magnonic spin current are evaluated numerically on the basis of micromagnetic simulations using solutions of the heat equation. We observe that the thermo-elastically induced magnonic spin current propagates on a distance larger than the characteristic size of thermal profile, an effect useful for applications in remote detection of spin caloritronics phenomena. Our findings point out that exploiting strain adds a new twist to heat-assisted magnetic switching and spin-current generation for spintronic applications.

  20. Magnetic insulation, power flow, and pulse power results on RITS-3

    International Nuclear Information System (INIS)

    Johnson, David L.; Smith, Ian; Corcoran, Patrick; Bailey, Vernon; Maenchen, John; Rovang, Dean; Molina, Isidro; Hahn, Kelly; Lucero, Robert; Kincy, Mark; Kitterman, David; Oliver, Bryan; Welch, Dale; Rose, David; Goldsack, Timothy J.; Phillips, Martin A.; Sinclair, Mark A.; Thomas, Kenneth J.

    2002-01-01

    RITS (Radiographic Integrated Test Stand) is an induction voltage adder designed by Sandia and PSD to provide 16-MV, 150-kA electron beams and other capabilities. Previous publications have reported on tests of a single pulse forming line and adder cell, including initial results of the effects of various degrees of non-uniform injection of current into the adder bore on magnetic insulation and power flow in the downstream MITL. Now RITS-3 has been constructed, consisting of three pfls driven by a common intermediate store; three induction cells, one driven by each pfl; a three-stage, 4-MV, 150-kA vacuum voltage adder; and an output MITL and diode. Here we report on (1) simulations of the three-stage adder using the MRC 3-D particle-in-cell code LSP that address the effects of injected current non-uniformities on magnetic insulation and power-flow both upstream and downstream in a multi-cell adder; (2) experimental results compared with simulations; and (3) initial performance of the RITS-3 pulse power

  1. Atomic-Scale Magnetism of Cr-Doped Bi2Se3 Thin Film Topological Insulators.

    Science.gov (United States)

    Liu, Wenqing; West, Damien; He, Liang; Xu, Yongbing; Liu, Jun; Wang, Kejie; Wang, Yong; van der Laan, Gerrit; Zhang, Rong; Zhang, Shengbai; Wang, Kang L

    2015-10-27

    Magnetic doping is the most common method for breaking time-reversal-symmetry surface states of topological insulators (TIs) to realize novel physical phenomena and to create beneficial technological applications. Here we present a study of the magnetic coupling of a prototype magnetic TI, that is, Cr-doped Bi2Se3, in its ultrathin limit which is expected to give rise to quantum anomalous Hall (QAH) effect. The high quality Bi2-xCrxSe3 epitaxial thin film was prepared using molecular beam epitaxy (MBE), characterized with scanning transimission electron microscopy (STEM), electrical magnetotransport, and X-ray magnetic circularly dichroism (XMCD) techniques, and the results were simulated using density functional theory (DFT) with spin-orbit coupling (SOC). We observed a sizable spin moment mspin = (2.05 ± 0.20) μB/Cr and a small and negative orbital moment morb = (-0.05 ± 0.02) μB/Cr of the Bi1.94Cr0.06Se3 thin film at 2.5 K. A remarkable fraction of the (CrBi-CrI)(3+) antiferromagnetic dimer in the Bi2-xCrxSe3 for 0.02 magnetic moments significantly lower than 3 μB/Cr predicted by Hund's rule.

  2. A Review of Irradiation Effects on Organic-Matrix Insulation

    International Nuclear Information System (INIS)

    Simon, N.J.

    1993-01-01

    This review assesses the data base on epoxy and polyimide matrix insulation to determine whether organic electric insulation systems can be used in the toroidal field (TF) magnets of next generation fusion devices such as ITER* and TPX*. Owing to the difficulties of testing insulation under fusion reactor conditions, there is a considerable mismatch between the ITER requirements and the data that are currently available. For example, nearly all of the high-dose (5 x 10 7 to 10 8 Gy) data obtained on epoxy and polyimide matrix insulation employed gamma irradiation, electron irradiation, or reactor irradiation with a fast neutron fluence far below 10 23 /m 2 , the fluence expected for the insulation at the TF magnets, as set forth in ITER conceptual design documents. Also, the neutron spectrum did not contain a very high energy (E (ge) 5 MeV) component. Such data underestimate the actual damage that would be obtained with the neutron fluence and spectrum expected at a TF magnet. Experiments on a polyimide (Kapton) indicate that gamma or electron doses or mixed gamma and neutron reactor doses would have to be downgraded by a factor of up to ten to simulate fusion neutron doses. Even when neutrons did constitute a significant portion of the total dose, B-containing E-glass reinforcement was often used; therefore, excess damage from the 10 B + n → 7 Li + α reaction occurred near the glass-epoxy interface. This problem can easily be avoided by substituting B-free glass (R, S, or T types)

  3. A Review of Irradiation Effects on Organic-Matrix Insulation

    Energy Technology Data Exchange (ETDEWEB)

    Simon, N.J.

    1993-06-01

    This review assesses the data base on epoxy and polyimide matrix insulation to determine whether organic electric insulation systems can be used in the toroidal field (TF) magnets of next generation fusion devices such as ITER* and TPX*. Owing to the difficulties of testing insulation under fusion reactor conditions, there is a considerable mismatch between the ITER requirements and the data that are currently available. For example, nearly all of the high-dose (5 x 10{sup 7} to 10{sup 8} Gy) data obtained on epoxy and polyimide matrix insulation employed gamma irradiation, electron irradiation, or reactor irradiation with a fast neutron fluence far below 10{sup 23}/m{sup 2}, the fluence expected for the insulation at the TF magnets, as set forth in ITER conceptual design documents. Also, the neutron spectrum did not contain a very high energy (E {ge} 5 MeV) component. Such data underestimate the actual damage that would be obtained with the neutron fluence and spectrum expected at a TF magnet. Experiments on a polyimide (Kapton) indicate that gamma or electron doses or mixed gamma and neutron reactor doses would have to be downgraded by a factor of up to ten to simulate fusion neutron doses. Even when neutrons did constitute a significant portion of the total dose, B-containing E-glass reinforcement was often used; therefore, excess damage from the {sup 10}B + n {yields} {sup 7}Li + {alpha} reaction occurred near the glass-epoxy interface. This problem can easily be avoided by substituting B-free glass (R, S, or T types).

  4. Experimental Observation of a Metal-insulator Transition in 2D at Zero Magnetic Field

    Science.gov (United States)

    Kravchenko, S. V.

    1996-03-01

    The scaling theory of Abrahams et al. ^1 has had considerable success in describing many features of metal-insulator transitions. Within this theory, which was developed for non-interacting electrons, no such transition is possible in two-dimensional electron systems (2DES) in the absence of a magnetic field. However, we show experimentally that an ultra-high-mobility 2DES on the surface of silicon does exhibit the signature of a true metal-insulator phase transition at zero magnetic field at a critical electron density n_c ~10^11 cm-2. The energy of electron-electron interactions, ignored in the scaling theory,^1 is the dominant parameter in this 2DES. The resistivity, ρ, is empirically found to scale near the critical point both with temperature T and electric field E so that it can be represented by the form ρ(T,n_s)=ρ(T/T_0(n_s)) as Earrow0 or ρ(E,n_s)=ρ(E/E_0(n_s)) as Tarrow0. At the transition, the resistivity is close to 3h/e^2. Both scaling parameters, T0 and E_0, show power law behavior at the critical point. This is characteristic of a true phase transition and strongly resembles, in particular, the superconductor-insulator transition in disordered thin films,^2 as well as the transition between quantum Hall liquid and insulator.^3 Many high-mobility samples from two different sources (Institute for Metrological Service, Russia, and Siemens AG, Germany) with different oxide thicknesses and gate materials have been studied and similar results were found. Work done in collaboration with J. E. Furneaux, Whitney Mason, V. M. Pudalov, and M. D'Iorio, supported by NSF. ^1 E. Abrahams, P. W. Anderson, D. C. Licciardello, and T. V. Ramakrishnan, Phys. Rev. Lett. 42, 673 (1979). ^2 Y. Liu, K. A. McGreer, B. Nease, D. B. Haviland, G. Martinez, J. W. Halley, and A. M. Goldman, Phys. Rev. Lett. 67, 2068 (1991). ^3 T. Wang, K. P. Clark, G. F. Spencer, A. M. Mack, and W. P. Kirk, Phys. Rev. Lett. 72, 709 (1994).

  5. Quantum phase transitions and local magnetism in Mott insulators: A local probe investigation using muons, neutrons, and photons

    Science.gov (United States)

    Frandsen, Benjamin A.

    Mott insulators are materials in which strong correlations among the electrons induce an unconventional insulating state. Rich interplay between the structural, magnetic, and electronic degrees of freedom resulting from the electron correlation can lead to unusual complexity of Mott materials on the atomic scale, such as microscopically heterogeneous phases or local structural correlations that deviate significantly from the average structure. Such behavior must be studied by suitable experimental techniques, i.e. "local probes", that are sensitive to this local behavior rather than just the bulk, average properties. In this thesis, I will present results from our studies of multiple families of Mott insulators using two such local probes: muon spin relaxation (muSR), a probe of local magnetism; and pair distribution function (PDF) analysis of x-ray and neutron total scattering, a probe of local atomic structure. In addition, I will present the development of magnetic pair distribution function analysis, a novel method for studying local magnetic correlations that is highly complementary to the muSR and atomic PDF techniques. We used muSR to study the phase transition from Mott insulator to metal in two archetypal Mott insulating systems: RENiO3 (RE = rare earth element) and V2O3. In both of these systems, the Mott insulating state can be suppressed by tuning a nonthermal parameter, resulting in a "quantum" phase transition at zero temperature from the Mott insulating state to a metallic state. In RENiO3, this occurs through variation of the rare-earth element in the chemical composition; in V 2O3, through the application of hydrostatic pressure. Our results show that the metallic and Mott insulating states unexpectedly coexist in phase-separated regions across a large portion of parameter space near the Mott quantum phase transition and that the magnitude of the ordered antiferromagnetic moment remains constant across the phase diagram until it is abruptly

  6. Study of high field Nb3Sn superconducting dipoles: electrical insulation based made of ceramic and magnetic design

    International Nuclear Information System (INIS)

    Rochepault, E.

    2012-01-01

    In the framework of LHC upgrades, significant efforts are provided to design accelerator magnets using the superconducting alloy Nb 3 Sn, which allows to reach higher magnetic fields (≥12 T). The aim of this thesis is to propose new computation and manufacturing methods for high field Nb 3 Sn dipoles. A ceramic insulation, previously designed at CEA Saclay, has been tested for the first time on cables, in an accelerator magnet environment. Critical current measures, under magnetic field and mechanical stress, have been carried out in particular. With this test campaign, the current ceramic insulation has been shown to be too weak mechanically and the critical current properties are degraded. Then a study has been conducted, with the objective to improve the mechanical strength of the insulation and better distribute the stress inside the cable. Methods of magnetic design have also been proposed, in order to optimize the coils shape, while fulfilling constraints of field homogeneity, operational margins, forces minimization... Consequently, several optimization codes have been set up. They are based on new methods using analytical formulas. A 2D code has first been written for block designs. Then two 3D codes have been realized for the optimization of dipole ends. The former consists in modeling the coil with elementary blocs and the latter is based on a modeling of the superconducting cables with ribbons. These optimization codes allowed to propose magnetic designs for high field accelerator magnets. (author) [fr

  7. Spectroscopic observations of ion line-emission from a magnetically insulated ion diode

    International Nuclear Information System (INIS)

    Maron, Y.; Peng, H.S.; Rondeau, G.D.; Hammer, D.A.

    1984-01-01

    Excited ions, produced in the surface-flashover plasma in a magnetically insulated diode, spontaneously emit light from the anode plasma region as well as (if the life time of the excited level is at least a few ns) from the diode acceleration gap. The emission lines of the ions traversing the gap are shifted from their natural wavelength because of the Stark effect due to the diode electric field. If the light is viewed transverse to the acceleration direction, the line width will be mostly determined by Doppler broadening due to ion transverse velocities. The authors use the OMNI II diode (up to 500 kV, 25 kA, 80 ns) with an insulating B field of ≅12 kG and an A-K gap of ≅7mm. The light emission from the entire 6.5 x 12 cm area in front of the anode is viewed parallel to the applied B field. A spectral resolution of 0.5 A is obtained by dispersing the light using a spectrometer followed by 6 optical fibers attached to PM-tubes. Each channel output is calibrated in situ. The spatial resolution across the gap could be made as small as 0.3 mm and the temporal resolution was varied between a few to a few tens of ns. The line spectral profile is obtained at a single discharge for a given distance from the anode surface

  8. Exotic magnetism and spin-orbit-assisted Mott insulating state in a 3 d -5 d double perovskite

    Science.gov (United States)

    Cavichini, A. S.; Orlando, M. T.; Depianti, J. B.; Passamai, J. L.; Damay, F.; Porcher, F.; Granado, E.

    2018-02-01

    The magnetic structure of Ca2MnReO6 double perovskite is investigated by neutron powder diffraction and bulk magnetization, showing dominant noncollinear Mn magnetic moments [4.35 (7 ) μB] that are orthogonally aligned with the small Re moments [0.22 (4 ) μB] . Ab initio electronic structure calculations show that the strong spin-orbit coupling for Re 5 d electrons combined with a relatively modest on-site Coulomb repulsion (UeffR e≳0.6 eV) is sufficient to render this material insulating. This is a rare example of spin-orbit-assisted Mott insulator outside the realm of iridates, with remarkable magnetic properties.

  9. Shrink Tube Insulation Apparatus for Rebco Superconducting Tapes for Use in High Field Magnets

    CERN Document Server

    Whittington, Andrew

    An increasing number of applications require the use of high temperature superconductors (HTS) such as (RE=Rare Earth) Ba2Cu3O7-x (REBCO) coated conductors [1]. HTS conductors show particularly great potential for high field magnets applications [1] due to their high upper critical fields [2], But several groups have shown that REBCO coated conductors are prone to delamination failure [3] [4] [5]. Under relatively low transverse stress the HTS film separates from the substrate and the conductor degrades [6]. This is problematic due to high transverse stresses that occur in fully epoxy impregnated solenoids wound with this conductor. Application of thin walled heat shrink tubing introduces a weak plane around the conductor, preventing delamination degradation [7]. However, manual application of the shrink tubing is impractical, requiring three operators limited to insulating 100 m lengths or less of REBCO conductor. The high risk of damage to the conductor, also associated with this process, shows the need for...

  10. Experimental and theoretical investigations of a magnetically insulated line oscillator (MILO)

    Science.gov (United States)

    Calico, Steve E.; Clark, M. Collins; Lemke, Raymond W.; Scott, Michael C.

    1995-09-01

    The Electromagnetic Sources Division of the Advanced Weapons and Survivability Directorate at the Phillips Laboratory is dedicated to the development of HPM sources. This paper will report on the recent work done on a magnetically insulated line oscillator (MILO). The MILO is a linear magnetron type device with the bias magnetic field applied by the current flowing through the tube, hence no externally applied magnetic field is required. This work concentrates on the axial extraction of the microwave power in contrast to most of the previous work which concentrated on the radial extraction of power. Theory has predicted and experiments have shown that a number of parameters, including but not limited to, the boundaries at the ends of the slow wave structure, the location of the emission region, the method of launching the beam, the anode-cathode gap, and the number of cavities, all have a significant effect on the operation of the tube. A number of tests at diode voltages from 150 kV to over 500 kV have been conducted to gain a better understanding of the mechanisms controlling the operation of the device. To data RF powers over 1 GW for short pulses (< 100 ns) have been achieved with the goal of further experiments and corresponding simulations are reported here.

  11. Experimental research on time-resolved evolution of cathode plasma expansion velocity in a long pulsed magnetically insulated coaxial diode

    Science.gov (United States)

    Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Ge, Xingjun; Gao, Jingming

    2018-02-01

    Unlike planar diodes, separate research of the axial and radial plasma expansion velocities is difficult for magnetically insulated coaxial diodes. Time-resolved electrical diagnostic which is based on the voltage-ampere characteristics has been employed to study the temporal evolution of the axial and radial cathode plasma expansion velocities in a long pulsed magnetically insulated coaxial diode. Different from a planar diode with a "U" shaped profile of temporal velocity evolution, the temporal evolution trend of the axial expansion velocity is proved to be a "V" shaped profile. Apart from the suppression on the radial expansion velocity, the strong magnetic field is also conducive to slowing down the axial expansion velocity. Compared with the ordinary graphite cathode, the carbon velvet and graphite composite cathode showed superior characteristics as judged by the low plasma expansion velocity and long-term electrical stability as a promising result for applications where long-pulsed and reliable operation at high power is required.

  12. Numerical simulation of cathode plasma dynamics in magnetically insulated vacuum transmission lines

    International Nuclear Information System (INIS)

    Thoma, C.; Genoni, T. C.; Welch, D. R.; Rose, D. V.; Clark, R. E.; Miller, C. L.; Stygar, W. A.; Kiefer, M. L.

    2015-01-01

    A novel algorithm for the simulation of cathode plasmas in particle-in-cell codes is described and applied to investigate cathode plasma evolution in magnetically insulated transmission lines (MITLs). The MITL electron sheath is modeled by a fully kinetic electron species. Electron and ion macroparticles, both modeled as fluid species, form a dense plasma which is initially localized at the cathode surface. Energetic plasma electron particles can be converted to kinetic electrons to resupply the electron flux at the plasma edge (the “effective” cathode). Using this model, we compare results for the time evolution of the cathode plasma and MITL electron flow with a simplified (isothermal) diffusion model. Simulations in 1D show a slow diffusive expansion of the plasma from the cathode surface. But in multiple dimensions, the plasma can expand much more rapidly due to anomalous diffusion caused by an instability due to the strong coupling of a transverse magnetic mode in the electron sheath with the expanding resistive plasma layer

  13. Absorbed dose measurements of insulating material for TRISTAN magnets by IR spectrometry

    International Nuclear Information System (INIS)

    Endo, Kuninori; Ohsawa, Yasunobu; Michikawa, Taichi.

    1995-01-01

    Absorbed dose measurements of the insulating material for 29GeV TRISTAN Main-Ring magnets were carried out with the Infrared spectrometry. From the fact that carbonyl radical is induced in epoxy resin by irradiation, infrared absorbance in the range of 1705-1720 cm -1 due to carbonyl radicals was applied to the estimations of the absorbed dose of the epoxy resin. Relationship between absorbance of carbonyl band and absorbed dose was investigated exposing the epoxy resin in two irradiation fields, TRISTAN MR and irradiation facility of 3kCi 60 Co source. From this work, it was found that IR absorbance method could be applied to the absorbed dose measurements from 10 3 to 10 7 Gy and that absorbed doses obtained from 31 specimens of epoxy resin shaved from coils of TRISTAN MR magnets had a distribution extending from 2.6 x 10 3 to 1.07 x 10 7 Gy, mostly order of 10 4 to 10 5 Gy. (author)

  14. 55-TW magnetically insulated transmission-line system: Design, simulations, and performance

    Directory of Open Access Journals (Sweden)

    W. A. Stygar

    2009-12-01

    Full Text Available We describe herein a system of self-magnetically insulated vacuum transmission lines (MITLs that operated successfully at 20 MA, 3 MV, and 55 TW. The system delivered the electromagnetic-power pulse generated by the Z accelerator to a physics-package load on over 1700 Z shots. The system included four levels that were electrically in parallel. Each level consisted of a water flare, vacuum-insulator stack, vacuum flare, and 1.3-m-radius conical outer MITL. The outputs of the four outer MITLs were connected in parallel by a 7.6-cm-radius 12-post double-post-hole vacuum convolute. The convolute added the currents of the four outer MITLs, and delivered the combined current to a single 6-cm-long inner MITL. The inner MITL delivered the current to the load. The total initial inductance of the stack-MITL system was 11 nH. A 300-element transmission-line-circuit model of the system has been developed using the tl code. The model accounts for the following: (i impedance and electrical length of each of the 300 circuit elements, (ii electron emission from MITL-cathode surfaces wherever the electric field has previously exceeded a constant threshold value, (iii Child-Langmuir electron loss in the MITLs before magnetic insulation is established, (iv MITL-flow-electron loss after insulation, assuming either collisionless or collisional electron flow, (v MITL-gap closure, (vi energy loss to MITL conductors operated at high lineal current densities, (vii time-dependent self-consistent inductance of an imploding z-pinch load, and (viii load resistance, which is assumed to be constant. Simulations performed with the tl model demonstrate that the nominal geometric outer-MITL-system impedance that optimizes overall performance is a factor of ∼3 greater than the convolute-load impedance, which is consistent with an analytic model of an idealized MITL-load system. Power-flow measurements demonstrate that, until peak current, the Z stack-MITL system

  15. Thermally driven magnon transport in the magnetic insulator Yttrium Iron Garnet

    International Nuclear Information System (INIS)

    Agrawal, Milan

    2014-01-01

    The research work presented in this thesis covers the investigation of spin-caloric phenomena in ferromagnetic-normal metal heterostructures. These phenomena explore the interaction of heat with spin systems and mainly deal with the generation and the manipulation of spin currents by means of heat currents (phonons). The significance of spin currents is widely seen in developing new fundamental concepts of physics as well as in the industry of magnetic memories. Analogous to the classical Seebeck effect, the generation of a spin current in a spin system by the application of heat currents is known as the spin Seebeck effect (SSE). This mode of spin current generation has recently attracted much scientific attention due to the existence of the spin Seebeck effect in a wide variety of magnetic materials (spin systems), considering from insulators to metals. The potential applications of this effect, in particular to generate electricity out of waste heat, make the effect even more attractive. Generally, spin systems can be classified into either a system constituting the traveling spins carried by free electrons or into a system of spin waves, collective excitations of magnetic moments in the wavevector space. Having the advantage of being free from free-electronic charges, an electrical-insulating-ferromagnetic system of spin waves overcomes the limitation of short propagation lengths of pure spin currents in metals. The long propagation length of spin currents carried by propagating spin waves is crucial for building-up spin-electronic (spintronic) circuits and spin logics for fast computation. For such purposes, the ferrimagnetic insulator Yttrium Iron Garnet (YIG) is a promising material candidate due to its lowest known magnetic damping which offers macroscopic propagation lengths of spin currents. In the framework of this thesis, a detailed investigation of the interaction of phonons with magnons, the quanta of spin waves, in single crystalline YIG films are

  16. Simulational Investigation of a High-Efficiency X-Band Magnetically Insulated Line Oscillator

    Science.gov (United States)

    Wang, Xiaoyu; Fan, Yuwei

    2015-10-01

    The magnetically insulated line oscillator (MILO) is a gigawatt-class, coaxial crossed-field microwave tube, which is at present a major hotspot in the field of high-power microwaves (HPM) research. In order to improve the power conversion efficiency and eliminate or at least minimize anode plasma formation in the load region and radio frequency (RF) breakdown in the slow wave structure (SWS) section, an X-band MILO is presented and investigated numerically with KARAT code. The design idea is briefly presented and the simulation results are given and discussed. In the simulation, HPM is generated with peak power of 3.4 GW, maximum electric field of about 1 MV/cm, and peak power conversion efficiency of 14.0%, when the voltage is 559.1 kV and the current is 43.2 kA. The microwave frequency is pure and falls in the X-band of 9.0 GHz. The theoretical investigation and the simulation results are given to prove that the anode plasma formation and the RF breakdown can be effectively avoided or at least minimized, respectively. supported by National Natural Science Foundation of China (No. 11075210) and the Special Financial Grant from the China Postdoctoral Science Foundation (No. 201104761)

  17. A Ku-band magnetically insulated transmission line oscillator with overmoded slow-wave-structure

    Science.gov (United States)

    Jiang, Tao; He, Jun-Tao; Zhang, Jian-De; Li, Zhi-Qiang; Ling, Jun-Pu

    2016-12-01

    In order to enhance the power capacity, an improved Ku-band magnetically insulated transmission line oscillator (MILO) with overmoded slow-wave-structure (SWS) is proposed and investigated numerically and experimentally. The analysis of the dispersion relationship and the resonant curve of the cold test indicate that the device can operate at the near π mode of the TM01 mode, which is useful for mode selection and control. In the particle simulation, the improved Ku-band MILO generates a microwave with a power of 1.5 GW and a frequency of 12.3 GHz under an input voltage of 480 kV and input current of 42 kA. Finally, experimental investigation of the improved Ku-band MILO is carried out. A high-power microwave (HPM) with an average power of 800 MW, a frequency of 12.35 GHz, and pulse width of 35 ns is generated under a diode voltage of 500 kV and beam current of 43 kA. The consistency between the experimental and simulated far-field radiation pattern confirms that the operating mode of the improved Ku-band MILO is well controlled in π mode of the TM01 mode. Project supported partly by the National Natural Science Foundation of China (Grant No. 61171021).

  18. Application of magnetically insulated transmission lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Poukey, J.W.; Turman, B.N.

    1993-01-01

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently the authors used a MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r b < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. The authors' success with the MITL technology led them to investigate the application to higher energy accelerator designs. They have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30-50-ns FWHM output pulse

  19. Application of Magnetically Insulated Transmission Lines for high current, high voltage electron beam accelerators

    International Nuclear Information System (INIS)

    Shope, S.L.; Mazarakis, M.G.; Frost, C.A.; Poukey, J.W.; Turman, B.N.

    1991-01-01

    Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA, HERMES III, and SABRE. Most recently we used at MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r ρ < 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v perpendicular/c = β perpendicular ≤ 0.1. In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. Our success with the MITL technology led us to investigate the application to higher energy accelerator designs. We have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities. Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30--50 ns FWHM output pulse. 10 refs

  20. Design of permanent magnet motor actuator used in 550 kV gas-insulated switchgear disconnector

    OpenAIRE

    Kejian Shi; Xin Lin; Jianyuan Xu

    2015-01-01

    To improve the operating characteristics of disconnector, a limited rotating angle permanent magnet motor actuator is presented in this article. The mathematical relationship between the moving contact stroke and rotation angle of motor is obtained by analyzing the dynamical coordination characteristics of motor actuator used in 550 kV gas-insulated switchgear disconnector. The electromagnetic field equation of motor, motive equation of rotor, and circuit equation of winding are solved simult...

  1. Spin-related tunneling through a nanostructured electric-magnetic barrier on the surface of a topological insulator.

    Science.gov (United States)

    Wu, Zhenhua; Li, Jun

    2012-01-27

    We investigate quantum tunneling through a single electric and/or magnetic barrier on the surface of a three-dimensional topological insulator. We found that (1) the propagating behavior of electrons in such system exhibits a strong dependence on the direction of the incident electron wavevector and incident energy, giving the possibility to construct a wave vector and/or energy filter; (2) the spin orientation can be tuned by changing the magnetic barrier structure as well as the incident angles and energies.PACS numbers: 72.25.Dc; 73.20.-r; 73.23.-b; 75.70.-i.

  2. A long-pulse repetitive operation magnetically insulated transmission line oscillator.

    Science.gov (United States)

    Fan, Yu-Wei; Zhong, Hui-Huang; Zhang, Jian-De; Shu, Ting; Liu, Jin Liang

    2014-05-01

    The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

  3. Magnetism of insulator phase in SrRu1-x Mn x O3 (0.4≤x≤0.6)

    International Nuclear Information System (INIS)

    Kawanaka, H.; Satoh, C.; Yokoyama, M.; Kitazawa, H.; Suzuki, O.; Kido, G.; Bando, H.; Nishihara, Y.

    2007-01-01

    Temperature dependence of magnetization was measured in the insulator phase of SrRu 1- x Mn x O 3 (0.4≤x≤0.6) at magnetic fields up to 15 T. For the sample with x=0.6, the peak of the magnetization changes from 210 to 250 K with increasing magnetic field up to 5 T and slightly decreases above it. The paramagnetic Curie-Weiss temperature is positive (180 K). The anti-ferromagnetic Neel temperature obtained from the neutron diffraction experiment agrees with the peak temperature measured in high magnetic fields. Discussion of the magnetization peak in high and low magnetic fields is given

  4. The role of short-range magnetic correlations in the gap opening of topological Kondo insulators.

    Science.gov (United States)

    Ramos, E; Franco, R; Silva-Valencia, J; Foglio, M E; Figueira, M S

    2017-08-31

    In this article we investigate the effects of short-range anti-ferromagnetic correlations on the gap opening of topological Kondo insulators. We add a Heisenberg term to the periodic Anderson model at the limit of strong correlations in order to allow a small degree of hopping of the localized electrons between neighboring sites of the lattice. This new model is adequate for studying topological Kondo insulators, whose paradigmatic material is the compound [Formula: see text]. The main finding of the article is that the short-range antiferromagnetic correlations, present in some Kondo insulators, contribute decisively to the opening of the Kondo gap in their density of states. These correlations are produced by the interaction between moments on the neighboring sites of the lattice. For simplicity, we solve the problem on a two dimensional square lattice. The starting point of the model is the [Formula: see text] ions orbitals, with [Formula: see text] multiplet in the presence of spin-orbit coupling. We present results for the Kondo and for the antiferromagnetic correlation functions. We calculate the phase diagram of the model, and as we vary the [Formula: see text] level position from the empty regime to the Kondo regime, the system develops metallic and topological Kondo insulator phases. The band structure calculated shows that the model describes a strong topological insulator.

  5. Magnetic and structural properties of Mn-doped Bi.sub.2./sub.Se.sub.3./sub. topological insulators

    Czech Academy of Sciences Publication Activity Database

    Tarasenko, R.; Vališka, M.; Vondráček, Martin; Horáková, Kateřina; Tkáč, V.; Carva, K.; Baláž, P.; Holý, V.; Springholz, G.; Sechovský, V.; Honolka, Jan

    2016-01-01

    Roč. 481, Jan (2016), 262-267 ISSN 0378-4363 R&D Projects: GA ČR(CZ) GA14-30062S; GA MŠk LO1409; GA MŠk(CZ) LM2011029 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : topological insulator * Mn-doped Bi 2 Se 3 * X-ray diffraction * X-ray photoemission * spectroscopy * ferromagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. Design and performance estimation of a 35 T 40 mm no-insulation all-REBCO user magnet

    Science.gov (United States)

    Kim, Kwangmin; Bhattarai, Kabindra R.; Jang, Jae Young; Hwang, Young Jin; Kim, Kwanglok; Yoon, Sangwon; Lee, SangGap; Hahn, Seungyong

    2017-06-01

    This paper presents a design of a 35 T 40 mm winding diameter no-insulation standalone magnet that consists of a stack of 52 double pancake (DP) coils wound with multi-width REBCO tapes. The inner and outer diameters and height of the magnet are 40 mm, 221.6 mm, and 628 mm, respectively. It is designed to generate 35 T at an operating current (I op) of 179.8 A in a bath of liquid helium at 4.2 K. All the DP coils will be ‘dry’ wound without epoxy, making turns within the DP coils to be essentially ‘self-supporting,’ which is effective to reduce the magnetic stress. To reduce the magnet charging time constant, the so-called ‘metallic cladding’ REBCO tapes will be adopted, where a 1-2 μm thick stainless steel layer surrounds the tapes hermetically. With an average surface contact resistance (R ct) of 170 μ {{Ω }} cm-2, experimentally obtained from a charging test of our recent 3 T 100 mm stainless steel cladding REBCO magnet, the charging time constant of the 35 T magnet was estimated to be 3.01 minutes, though the magnet will be energized substantially slower over a few hours to reduce ac loss and Joule heating from radial turn-to-turn leak currents. A preliminary post-quench analysis, based on our lumped equivalent circuit model, was performed; the total stored energy of 1.79 MJ (magnet inductance: 110.5 H) was expected to be discharged in approximately 1.28 seconds after a quench due to the fast electromagnetic quench propagation among the DP coils, while the peak hot spot temperature was estimated to rise to 94 K, acceptable for a safe quench of a REBCO magnet.

  7. ''SMILE'': A Self Magnetically Insulated Transmission LinE adder for the 8-stage RADLAC II accelerator

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poukey, J.W.; Shope, S.L.; Frost, C.A.; Turman, B.N.; Ramirez, J.J.; Prestwich, K.R.; Pankuch, P.J.

    1991-01-01

    The RADLAC II Self Magnetically Insulated Transmission LinE ''SMILE'' is a coaxial wave guide structure that is composed of two regions: (a) a 9.5-m voltage adder and (b) a 3-m long extension section. The adder section provides for the addition of the input voltages from the individual water-dielectric pulse forming line feeds. The extension section isolates the adder from the magnetically immersed foilless diode electron source load and efficiently transports the pulsed power out from the deionized water tank of the device. The SMILE modification of the RADLAC II accelerator enabled us to produce high quality beams of up to 14 MV, 100 kA. The design and the experimental evaluation of SMILE will be presented and compared with numerical simulation predictions. 12 refs., 9 figs., 1 tab

  8. SMILE'': A Self Magnetically Insulated Transmission LinE adder for the 8-stage RADLAC II accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, M.G.; Poukey, J.W.; Shope, S.L.; Frost, C.A.; Turman, B.N.; Ramirez, J.J.; Prestwich, K.R. (Sandia National Labs., Albuquerque, NM (USA)); Pankuch, P.J. (EG and G Energy Measurements Group, Inc., Albuquerque, NM (USA). Special Projects)

    1991-01-01

    The RADLAC II Self Magnetically Insulated Transmission LinE SMILE'' is a coaxial wave guide structure that is composed of two regions: (a) a 9.5-m voltage adder and (b) a 3-m long extension section. The adder section provides for the addition of the input voltages from the individual water-dielectric pulse forming line feeds. The extension section isolates the adder from the magnetically immersed foilless diode electron source load and efficiently transports the pulsed power out from the deionized water tank of the device. The SMILE modification of the RADLAC II accelerator enabled us to produce high quality beams of up to 14 MV, 100 kA. The design and the experimental evaluation of SMILE will be presented and compared with numerical simulation predictions. 12 refs., 9 figs., 1 tab.

  9. Deuteron flux production in a small high-voltage high-current diode with pulsed magnetic insulation

    Science.gov (United States)

    Shikanov, A. E.; Vovchenko, E. D.; Isaev, A. A.; Kozlovskii, K. I.; Shatokhin, V. L.

    2017-06-01

    The results of new studies on the production of accelerated deuteron fluxes in a small ion diode with pulsed magnetic insulation of electrons have been presented. A plasma anode of the diode has been formed under the action of a 1.06 μm laser radiation with a pulse duration of 10 ns, a pulse energy of up to 1 J, and a power density on the target of 5 × 1015 W m-2. An accelerating voltage of up to 300 kV has been created using an Arkad'ev-Marx pulsed voltage generator with a stored energy of 50 J and a repetition rate of 1 Hz. A magnetic field of higher than 0.6 T for insulating electrons has been formed by a current pulse of the first cascade of the generator in a spiral line before a conical cascade. Stable deuteron acceleration to 300 keV with a current of up to 1.5 kA and a pulse duration of 0.3 μs has been achieved.

  10. The magnetic response at the metal-insulator transition in La1 - xSrxTiO3 (abstract)

    Science.gov (United States)

    Osborn, R.; Aronson, M. C.; Goremychkin, E. A.; Greedan, J. E.

    1996-04-01

    We report on recent inelastic neutron scattering measurements of the magnetic response close to the metal-insulator transition in La1-xSrxTiO3. Specific heat and susceptibility data from Tokura et al. give evidence for a divergent effective mass at the critical concentration xc=0.05 in agreement with recent mean-field theories of the transition. The mass enhancement is believed to arise from the formation of a d-electron resonance at the Fermi energy close to the transition. The aim of this investigation is to look for evidence of this resonance in the dynamic magnetic susceptibility. We studied samples with x=0, 0.05, and 0.2 using incident energies between 25 and 200 meV. After correction for the phonon scattering, we observe a broad response above a threshold of 20-30 meV extending to over 100 meV. In addition, the Mott insulating antiferromagnet (x=0) has a peak at 40 meV, consistent with the estimated activation energy derived from resistivity measurements. This feature becomes washed out with temperature and doping. Possible origins for this peak are discussed.

  11. Ferromagnetism of magnetically doped topological insulators in CrxBi2-xTe3 thin films

    Science.gov (United States)

    Ni, Y.; Zhang, Z.; Nlebedim, I. C.; Hadimani, R. L.; Tuttle, G.; Jiles, D. C.

    2015-05-01

    We investigated the effect of magnetic doping on magnetic and transport properties of Bi2Te3 thin films. CrxBi2-xTe3 thin films with x = 0.03, 0.14, and 0.29 were grown epitaxially on mica substrate with low surface roughness (˜0.4 nm). It is found that Cr is an electron acceptor in Bi2Te3 and increases the magnetization of CrxBi2-xTe3. When x = 0.14 and 0.29, ferromagnetism appears in CrxBi2-xTe3 thin films, where anomalous Hall effect and weak localization of magnetoconductance were observed. The Curie temperature, coercivity, and remnant Hall resistance of thin films increase with increasing Cr concentration. The Arrott-Noakes plot demonstrates that the critical mechanism of the ferromagnetism can be described better with 3D-Heisenberg model than with mean field model. Our work may benefit for the practical applications of magnetic topological insulators in spintronics and magnetoelectric devices.

  12. Critical Mechanism of Magnetic Doped CrxBi2-xTe3 Topological Insulator Thin Films

    Science.gov (United States)

    Zhang, Zhen; Ni, Yan; Hadimani, Ravi; Jiles, David; Nlebedim, Cajetan

    2015-03-01

    Introducing magnetic dopants into topological insulators can lead to the opening of the surface band gap which can induce interesting phenomena such as the quantized anomalous Hall effect (QAH) and magnetoelectric effect. However, the critical properties of ferromagnetism in magnetic doped TIs are not well studied. In this work, we investigated the effect of magnetic doping on magnetic and transport response in Bi2Te3 thin films. CrxBi2-xTe3 thin films with x = 0.03, 0.14, and 0.29 were grown with low surface roughness (~ 0.4 nm). It is found that Cr is an n-type doping element, which reduces the carrier density of p-type Bi2Te3. Moreover, doping Cr induces long range ferromagnetism when x =0.14 and 0.29, where anomalous Hall effect and weak localization of magnetoconductance were observed. The Arrott-Noakes plot for CrxBi2-xTe3 demonstrates that the critical mechanism of the ferromagnetism can be described well with 3D-Heisenberg model. Our work may benefit for the practical applications of ferromagnetic TIs with opened surface band gap in spintronics and magnetoelectric devices. Authors would like to thank the financial support from the U.S. National Science Foundation under the Award No. 1201883.

  13. Influence of magnetism and correlation on the spectral properties of doped Mott insulators

    Science.gov (United States)

    Wang, Yao; Moritz, Brian; Chen, Cheng-Chien; Devereaux, Thomas P.; Wohlfeld, Krzysztof

    2018-03-01

    Unraveling the nature of the doping-induced transition between a Mott insulator and a weakly correlated metal is crucial to understanding novel emergent phases in strongly correlated materials. For this purpose, we study the evolution of spectral properties upon doping Mott insulating states by utilizing the cluster perturbation theory on the Hubbard and t -J -like models. Specifically, a quasifree dispersion crossing the Fermi level develops with small doping, and it eventually evolves into the most dominant feature at high doping levels. Although this dispersion is related to the free-electron hopping, our study shows that this spectral feature is, in fact, influenced inherently by both electron-electron correlation and spin-exchange interaction: the correlation destroys coherence, while the coupling between spin and mobile charge restores it in the photoemission spectrum. Due to the persistent impact of correlations and spin physics, the onset of gaps or the high-energy anomaly in the spectral functions can be expected in doped Mott insulators.

  14. SLPX TF coil, description and fem stress analysis

    International Nuclear Information System (INIS)

    Rogoff, P.; File, J.

    1979-01-01

    A step-wise stress analysis was performed on the SLPX-TF Coil. It started with simple two dimensional simulations of both the support plate and the conductors. The results of the first studies provided input for decisions on the size of and material members. Later a more complicated analysis was made, constructing a 3-dimensional model of the coil using COSMIC-NASTRAN Version 17.5 with its accompanying substructuring capabilities. The upper half of the coil is simulated and reduced to a manageable size by using three basic substructures. Loads and boundary conditions are applied at each substructure. This magnet is for fusion applications. 5 refs

  15. Magnetic and transport properties of Ni2MnGa-BaTiO3 metal-insulator particulate composite with percolation threshold

    International Nuclear Information System (INIS)

    Won, C.J.; Kambale, R.C.; Hur, N.

    2011-01-01

    Highlights: → The Ni 2 MnGa-BaTiO 3 type composites were first time prepared by solid state reaction. → Temperature dependent magnetic properties reveal two kinds of transitions in these composite. → The present materials show negative magnetoresistance effect. → The present studies on magnetic and electrical transport of metal/insulator (NMG/BTO) composites shows the resistivity change associated to filamentary conducting path at percolation threshold. - Abstract: Here we report the magnetic and transport properties of the metal/insulator (f NMG )Ni 2 MnGa/(1 - f NMG )BaTiO 3 composites. The X-ray diffraction study confirms the formation of both the phases in composite. The microstructure reveals that the conducting Ni 2 MnGa particles are well dispersed in an insulating BaTiO 3 matrix. Temperature dependent magnetization shows two transitions one above 300 K and other below 150 K. The temperature dependence resistivity near the percolation threshold f NMG = 0.4 had drastic changes which is higher than the f NMG = 0.5. Also the negative magnetoresistance effect was observed for the studied materials. We suggest that magnetic and transport properties at the percolation threshold can be adjusted by the strain from the surrounding insulator particle.

  16. Magnetic correlations and quantum criticality in the insulating antiferromagnetic, insulating spin liquid, renormalized Fermi liquid, and metallic antiferromagnetic phases of the Mott system V{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bao, W. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Broholm, C. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)]|[Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Aeppli, G. [NEC, 4 Independence Way, Princeton, New Jersey 08540 (United States); Carter, S.A. [Department of Physics, University of California, Santa Cruz, California 95064 (United States); Dai, P. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Rosenbaum, T.F. [James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States); Honig, J.M.; Metcalf, P. [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Trevino, S.F. [United States Army Research Laboratory, Adelphi, Maryland 20783 (United States)]|[Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

    1998-11-01

    Magnetic correlations in all four phases of pure and doped vanadium sesquioxide (V{sub 2}O{sub 3}) have been examined by magnetic thermal-neutron scattering. Specifically, we have studied the antiferromagnetic and paramagnetic phases of metallic V{sub 2{minus}y}O{sub 3}, the antiferromagnetic insulating and paramagnetic metallic phases of stoichiometric V{sub 2}O{sub 3}, and the antiferromagnetic and paramagnetic phases of insulating V{sub 1.944}Cr{sub 0.056}O{sub 3}. While the antiferromagnetic insulator can be accounted for by a localized Heisenberg spin model, the long-range order in the antiferromagnetic metal is an incommensurate spin-density wave, resulting from a Fermi surface nesting instability. Spin dynamics in the strongly correlated metal are dominated by spin fluctuations with a {open_quotes}single lobe{close_quotes} spectrum in the Stoner electron-hole continuum. Furthermore, our results in metallic V{sub 2}O{sub 3} represent an unprecedentedly complete characterization of the spin fluctuations near a metallic quantum critical point, and provide quantitative support for the self-consistent renormalization theory for itinerant antiferromagnets in the small moment limit. Dynamic magnetic correlations for {h_bar}{omega}{lt}k{sub B}T in the paramagnetic insulator carry substantial magnetic spectral weight. However, they are extremely short-ranged, extending only to the nearest neighbors. The phase transition to the antiferromagnetic insulator, from the paramagnetic metal and the paramagnetic insulator, introduces a sudden switching of magnetic correlations to a different spatial periodicity which indicates a sudden change in the underlying spin Hamiltonian. To describe this phase transition and also the unusual short-range order in the paramagnetic state, it seems necessary to take into account the orbital degrees of freedom associated with the degenerate {ital d} orbitals at the Fermi level in V{sub 2}O{sub 3}. {copyright} {ital 1998} {ital The American

  17. The solar kettle-thermos flask (SK-TF) and solar vacuum tube oven

    Energy Technology Data Exchange (ETDEWEB)

    Yak, Alex Kee Koo [AkayConsult Enterprise, Johor Bahru (Malaysia)

    2008-07-01

    The Solar Kettle-Thermos Flask (SK-TF) and Solar Vacuum Tube Oven (SaVeTao): A Cost Effective, Sustainable and Renewable Water Pasteurization and Food Processing System For The Developing World. Based on the perfect solar thermal energy harvesting paradigm of maximum solar radiation absorption and minimum loss of stored converted solar thermal energy, Solar Vacuum Glass Tubes (SVGT) indefinitely delivers solar pasteurized safe drinking water, powered solely by free solar energy. The SVGT is the heart of the SK-TF. Being vacuum insulated, the SK-TF doubles up as a vacuum flask, delivering stored solar heated water in the morning before the Sun is up. With a high stagnation temperature of more than 200 C, the SK-TF can also be used for other heating purposes e.g. an oven or autoclave. Powered solely by free solar energy, the SK-TF and SaVeTaO could very well be the answer in providing safe solar pasteurized drinking water and cooking to the global poor and needy in a sustainable and renewable way. (orig.)

  18. Impact of lattice strain on the tunnel magnetoresistance in Fe/insulator/Fe and Fe/insulator/La0.67Sr0.33MnO3 magnetic tunnel junctions

    KAUST Repository

    Useinov, Arthur

    2013-08-19

    The objective of this work is to describe the tunnel electron current in single-barrier magnetic tunnel junctions within an approach that goes beyond the single-band transport model. We propose a ballistic multichannel electron transport model that can explain the influence of in-plane lattice strain on the tunnel magnetoresistance as well as the asymmetric voltage behavior. We consider as an example single-crystal magnetic Fe(110) electrodes for Fe/insulator/Fe and Fe/insulator/La0.67Sr0.33MnO3 tunnel junctions, where the electronic band structures of Fe and La0.67Sr0.33MnO3 are derived by ab initio calculations.

  19. Fatigue behavior of an insulation system for the ITER magnets in the load and strain controlled mode

    Energy Technology Data Exchange (ETDEWEB)

    Prokopec, R. [Atomic Institute of the Austrian Universities, Vienna University of Technology, 1020 Vienna (Austria); Humer, K. [Atomic Institute of the Austrian Universities, Vienna University of Technology, 1020 Vienna (Austria)], E-mail: khumer@ati.ac.at; Weber, H.W. [Atomic Institute of the Austrian Universities, Vienna University of Technology, 1020 Vienna (Austria)

    2007-10-15

    The application of glass-fiber reinforced plastics as insulation materials for fusion magnet coils (e.g. of ITER) requires a full mechanical material characterization under ITER relevant conditions. The tension-tension fatigue test is useful to simulate the pulsed tokamak operation of the ITER coils in the relevant range of 10{sup 4}-10{sup 5} cycles. The fatigue process can be run under load or strain control, which may influence the material behavior under cyclic load conditions. Therefore, investigations were performed at 77 K using an industrial glass-fiber reinforced composite impregnated with epoxy resin. For both the load and the strain controlled mode, R-values of 0.3 and 0.5 and a frequency of 10 Hz were chosen. The results are discussed with respect to the lifetime performance of ITER.

  20. Comparison of the High-Frequency Magnetic Fluctuations in Insulating and Superconducting La2-xSrxCuO4

    DEFF Research Database (Denmark)

    Hayden, S.M.; Aeppli, G.; Mook, H.A.

    1996-01-01

    Inelastic neutron scattering performed at a spallation source is used to make absolute measurements of the dynamic susceptibility of insulating La2CuO4 and superconducting La1.86Sr0.14CuO4 over the energy range 15 less than or equal to (h) over bar omega less than or equal to 350 meV. The effect...... of Sr doping on the magnetic excitations is to cause a large broadening in the wave vector and a substantial change in the spectrum of the local spin fluctuations. Comparison of the two compositions reveals a new energy scale (h) over bar Gamma = 22 +/- 5 meV in La1.86Sr0.14CuO4....

  1. Heat conduction coefficient and coefficient of linear thermal expansion of electric insulation materials for superconducting magnetic system

    International Nuclear Information System (INIS)

    Deev, V.I.; Sobolev, V.P.; Kruglov, A.B.; Pridantsev, A.I.

    1984-01-01

    Results of experimental investigation of heat conduction coefficient and coefficient of linear thermal expansion and thermal shrinkages of the STEF-1 textolite-glass widely used in superconducting magnetic systems as electric insulating and structural material are presented. Samples of two types have been died: sample axisa is perpendicular to a plae of fiberglass layers ad sample axis is parallel to a plane of fiberglass layers. Heat conduction coefficient was decreased almost a five times with temperature decrease from 300 up to 5K and was slightly dependent on a sample type. Temperature variation of linear dimensions in a sample of the first type occurs in twice as fast as compared to the sample of the second type

  2. High-power electromagnetic wave in a magnetically insulated transmission line of the ANGARA-5-1 facility

    International Nuclear Information System (INIS)

    Samokhin, A. A.

    2010-01-01

    Studies of physical phenomena in magnetically insulated transmission lines (MITLs) of high-power pulsed current generators, analysis of operation of existing megavolt generators, and designing of new high-current generators with a power of up to ∼10 TW require creating an efficient numerical code for modeling the propagation of a high-power electromagnetic pulse in an MITL. This paper presents basic theoretical concepts of MITL operation in the framework of telegraph equations with allowance for electron leakage and variations in the electrode emissivity and analyzes propagation of an electromagnetic wave in the MITLs of the ANGARA-5-1 eight-module facility toward a dynamic load installed in the central unit with a matrix inductance.

  3. Band structure of a three-dimensional topological insulator quantum wire in the presence of a magnetic field.

    Science.gov (United States)

    Liu, Zhe; Jiang, Liwei; Zheng, Yisong

    2016-07-13

    By means of a numerical diagonalization approach, we calculate the electronic structure of a three-dimensional topological insulator (3DTI) quantum wire (QW) in the presence of a magnetic field. The QW can be viewed as a 3DTI film with lateral surfaces, when its rectangular cross section has a large aspect ratio. Our calculation indicates that nonchiral edge states emerge because of the confined states at the lateral surfaces. These states completely cover the valence band region among the Landau levels, which reasonably account for the absence of the [Formula: see text] quantum Hall effect in the relevant experimental works. In an ultrathin 3DTI film, inversion between the electron-type and hole-type bands occurs, which leads to the so-called pseudo-spin Hall effect. In a 3DTI QW with a square cross section, a tilting magnetic field can establish well-defined Landau levels in all four surfaces. In such a case, the quantum Hall edge states are localized at the square corners, characterized by the linearly crossing one-dimensional band profile. And they can be shifted between the adjacent corners by simply rotating the magnetic field.

  4. Effects on Magnetic Properties of GaMnAs Induced by Proximity of Topological Insulator Bi2Se3

    Science.gov (United States)

    Bac, Seul-Ki; Lee, Hakjoon; Lee, Sangyeop; Choi, Seonghoon; Lee, Sanghoon; Liu, X.; Dobrowolska, M.; Furdyna, J. K.

    2018-04-01

    Effects induced by a topological insulator Bi2Se3 on the magnetic properties of an adjacent GaMnAs film have been investigated using transport measurements. We observed three conspicuous effects in the GaMnAs layer induced by the proximity of the Bi2Se3 overlayer. First, our resistivity data as a function of temperature show that the GaMnAs layer adjacent to the Bi2Se3 displayed strongly metallic behavior, as compared with the GaMnAs control specimen. Second, the Curie temperature of the GaMnAs in the bilayer was observed to be higher than that of the control layer, in our case by nearly a factor of two. Finally, we observed significant changes in the in-plane magnetic anisotropy of the GaMnAs in the bilayer, in the form of much higher values of both cubic and uniaxial anisotropy parameters. This latter feature manifests itself in a rather spectacular increase of the coercive field observed in magnetization reversal across the in-plane hard axis. These results suggest that proximity of an adjacent Bi2Se3 layer represents an important tool for modifying and controlling the ferromagnetic properties of GaMnAs film, and could thus be used to optimize this and similar materials for applications in spintronic devices.

  5. Examples of occupational exposure to electric and magnetic fields at 110-kV gas-insulated substations (GISs).

    Science.gov (United States)

    Korpinen, Leena; Pääkkönen, Rauno

    2015-02-01

    The objectives of the study were to present examples of occupational exposure to electric and magnetic fields at gas-insulated substations (GISs) and to analyse the exposure according to the new European Directive 2013/35/EU. The aim was also to describe the details of the measurements of this study at GISs. Electric and magnetic fields were measured (45 measurements in total) at two GISs in the Tampere region of Finland. Inside the GISs, magnetic field values varied from 0.4 to 43.0 µT, and electric fields from 5 to 90 V m(-1). In the cable room of GIS B, the maximum value was 250 µT (very near the cables). The values did not exceed the low or high action levels of the new Directive 2013/35/EU. In conclusion, it can be stated that at 110-kV GISs, workers are not exposed to electromagnetic fields (EMFs) higher than the new European Directive 2013/35/EU. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. Controllable magnetic doping of the surface state of a topological insulator

    DEFF Research Database (Denmark)

    Schlenk, T.; Bianchi, M.; Koleini, Mohammad

    2013-01-01

    principles calculations within density functional theory, these Fe substitutional impurities retain a large magnetic moment thus presenting an alternative scheme for magnetically doping the topological surface state. For both types of Fe doping, we see no indication of a gap at the Dirac point....

  7. Design and qualification of ITER CS and TF cooling inlets

    International Nuclear Information System (INIS)

    Decool, P.; Cloez, H.; Nicollet, S.; Serries, J.P.

    2005-01-01

    In the ITER superconducting magnets, the CIC (cable-in-conduit) conductors cooling is insured by supercritical helium forced flow in the central and annular parallel channels. In the Central Solenoid (CS), with a thick square jacket conductor, the helium inlet is in the highest field region at the inner bore pancake joggle, and it has to support the high hoop force stress level with a very low stress concentration factor. In the TF (toroidal field) magnets, a thin jacket circular conductor is wound in double pancakes, inserted into radial plates, stacked and embedded into a steel case. The helium inlets are located at the inner bore, in the limited space between the radial plates and the coil casing. The PF coils helium inlets, not studied here, are similar to the CS ones, but with a lower stress level. A complete qualification work on the CS and TF helium inlets is presented. A design optimisation was performed, by FEM analysis, resulting in acceptable stress level in both helium inlets. The welding procedure was qualified and specific fatigue life mock-ups were designed, analysed and manufactured using representative jacket materials. Fatigue life qualification at 4 K was performed in the German test facility applying the relevant loading and number of cycles. Hydraulic mock-ups were manufactured and qualified in the CEA test facility using GN2 at relevant Reynolds number. Pressure drop as well as flow distribution inside conductors' petals were measured. The mechanical and hydraulic results are presented. (authors)

  8. Design and qualification of ITER CS and TF cooling inlets

    Energy Technology Data Exchange (ETDEWEB)

    Decool, P.; Cloez, H.; Nicollet, S.; Serries, J.P. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Nyilas, A. [Forschungszentrum Karlsruhe GmbH (FZK) Institut fur Technische Physik (ITP), Karlsruhe (Germany)

    2005-07-01

    In the ITER superconducting magnets, the CIC (cable-in-conduit) conductors cooling is insured by supercritical helium forced flow in the central and annular parallel channels. In the Central Solenoid (CS), with a thick square jacket conductor, the helium inlet is in the highest field region at the inner bore pancake joggle, and it has to support the high hoop force stress level with a very low stress concentration factor. In the TF (toroidal field) magnets, a thin jacket circular conductor is wound in double pancakes, inserted into radial plates, stacked and embedded into a steel case. The helium inlets are located at the inner bore, in the limited space between the radial plates and the coil casing. The PF coils helium inlets, not studied here, are similar to the CS ones, but with a lower stress level. A complete qualification work on the CS and TF helium inlets is presented. A design optimisation was performed, by FEM analysis, resulting in acceptable stress level in both helium inlets. The welding procedure was qualified and specific fatigue life mock-ups were designed, analysed and manufactured using representative jacket materials. Fatigue life qualification at 4 K was performed in the German test facility applying the relevant loading and number of cycles. Hydraulic mock-ups were manufactured and qualified in the CEA test facility using GN2 at relevant Reynolds number. Pressure drop as well as flow distribution inside conductors' petals were measured. The mechanical and hydraulic results are presented. (authors)

  9. Plasmonics in Topological Insulators

    Directory of Open Access Journals (Sweden)

    Yi-Ping Lai

    2014-04-01

    Full Text Available With strong spin-orbit coupling, topological insulators have an insulating bulk state, characterized by a band gap, and a conducting surface state, characterized by a Dirac cone. Plasmons in topological insulators show high frequency-tunability in the mid-infrared and terahertz spectral regions with transverse spin oscillations, also called “spin-plasmons”. This paper presents a discussion and review of the developments in this field from the fundamental theory of plasmons in bulk, thin-film, and surface-magnetized topological insulators to the techniques of plasmon excitation and future applications.

  10. Effects of radiation at 5 K on organic insulators for superconducting magnets

    International Nuclear Information System (INIS)

    Coltman, R.R. Jr.; Klabunde, C.E.; Kernohan, R.H.; Long, C.J.

    1979-10-01

    Recent studies of the effects of irradiation at 5 K on organic insulators for fusion reactors have extended the irradiation dose from 2 x 10 9 to 1 x 10 10 rads and have looked for changes due to fast neutrons. For radiation conditions in this experiment the latter had little effect upon electrical and mechanical properties. At a dose of 1 x 10 10 rads, particle-filled epoxies are at ''end of life'' in terms of mechanical strength, while fiberglass-cloth-filled epoxies retain sufficient strength for use. Electrical-resistivity and voltage-breakdown vaues are reduced in some materials but remain in a usable range. Two sheet-type materials show excellent stability in their electrical properties

  11. Design of permanent magnet motor actuator used in 550 kV gas-insulated switchgear disconnector

    Directory of Open Access Journals (Sweden)

    Kejian Shi

    2015-03-01

    Full Text Available To improve the operating characteristics of disconnector, a limited rotating angle permanent magnet motor actuator is presented in this article. The mathematical relationship between the moving contact stroke and rotation angle of motor is obtained by analyzing the dynamical coordination characteristics of motor actuator used in 550 kV gas-insulated switchgear disconnector. The electromagnetic field equation of motor, motive equation of rotor, and circuit equation of winding are solved simultaneously for acquiring dynamical characteristics of motor. The electromagnetic-mechanical coupled calculating model of motor is established by finite element method, and magnetic saturation of stator tooth is calculated and analyzed. According to the operating principle of motor, the double-closed control system which collects the motor speed and contact stroke signal during the operation of disconnector is developed. The experimental results show that the opening and closing speeds of disconnector are 1.1 and 1.2 m/s, respectively, which meet design requirements. The speed-regulating operation of disconnector is also carried out so that the switching speed of disconnector can adjust by motor actuator and control system.

  12. Magnetization switching of a metallic nanomagnet via current-induced surface spin-polarization of an underlying topological insulator

    International Nuclear Information System (INIS)

    Roy, Urmimala; Dey, Rik; Pramanik, Tanmoy; Ghosh, Bahniman; Register, Leonard F.; Banerjee, Sanjay K.

    2015-01-01

    We consider a thermally stable, metallic nanoscale ferromagnet (FM) subject to spin-polarized current injection and exchange coupling from the spin-helically locked surface states of a topological insulator (TI) to evaluate possible non-volatile memory applications. We consider parallel transport in the TI and the metallic FM, and focus on the efficiency of magnetization switching as a function of transport between the TI and the FM. Transport is modeled as diffusive in the TI beneath the FM, consistent with the mobility in the TI at room temperature, and in the FM, which essentially serves as a constant potential region albeit spin-dependent except in the low conductivity, diffusive limit. Thus, it can be captured by drift-diffusion simulation, which allows for ready interpretation of the results. We calculate switching time and energy consumed per write operation using self-consistent transport, spin-transfer-torque (STT), and magnetization dynamics calculations. Calculated switching energies and times compare favorably to conventional spin-torque memory schemes for substantial interlayer conductivity. Nevertheless, we find that shunting of current from the TI to a metallic nanomagnet can substantially limit efficiency. Exacerbating the problem, STT from the TI effectively increases the TI resistivity. We show that for optimum performance, the sheet resistivity of the FM layer should be comparable to or larger than that of the TI surface layer. Thus, the effective conductivity of the FM layer becomes a critical design consideration for TI-based non-volatile memory

  13. Development of Magnetically Insulated Baffled Probe Cluster for Measurement of Energy Flux and Particle Flux in the Texas Helimak

    Science.gov (United States)

    Nogami, S. H.; Koepke, M.; Demidov, V.; Williams, C.; Gentle, K.

    2015-11-01

    Progress is reported in employing magnetically insulated baffled (MIB) probes in the Texas Helimak. Radial scans at the plasma edge of dc and ac space potential are presented. Like the Ball-Pen probe, the MIB probe shares the Langmuir probe simplicity and overcomes its shortcomings in the ability to make real-time measurements of plasma space potential, temperature, and energy/particle fluxes in magnetized plasma. By rotating the probe shaft to change the extent to which the baffle ``masks'' the probe collection area, the ratio between electron and ion probe current, and consequently the relative sensitivity of the floating-probe oscillations to space potential and electron/ion temperature, can be adjusted, thus allowing space potential fluctuations and electron/ion temperature fluctuations to be distinguished when measured at two different rotation angles. At the optimal rotation angle, the contribution of electron temperature and its fluctuations to the floating-potential measurement are eliminated and the space potential fluctuation phase is preserved. Support from DOE is gratefully acknowledged.

  14. Electrical and magnetic properties of superconducting-insulating Pr-doped GdBa2Cu3O7-y

    International Nuclear Information System (INIS)

    Yamani, Z.; Akhavan, M.

    1997-01-01

    An extensive study of magnetic, electrical transport, and structural properties of the normal and superconducting states of Gd 1-x Pr x Ba 2 Cu 3 O 7-y (GdPr-123) are presented. Ceramic compounds have been synthesized by the solid-state reaction technique, and characterized by x-ray-diffraction, scanning-electron-microscopy, thermogravimetric, and differential-thermal analyses. The superconducting transition temperature is reduced with increasing Pr content x in a nonlinear manner, in contrast to Abrikosov-Gor close-quote kov pair-breaking theory. Magnetic susceptibility measurements show that the nominal Pr valence is 3.86+, independently of x. A metal-insulator transition is observed at x cr ∼0.45, similar to that in the oxygen-deficient RBa 2 Cu 3 O 7-y (R-123) system. Based on this resemblance, we suggest that both Pr doping and oxygen deficiency act through the same mechanism. Hence, the environment surrounding the CuO 2 layers is important to high-T c superconductivity (HTSC). In this sense, HTSC cannot completely be a two-dimentional feature. A chain-plane-correlation effect is plausible. copyright 1997 The American Physical Society

  15. Electrical and magnetic properties of superconducting-insulating Pr-doped GdBa2Cu3O7-y

    Science.gov (United States)

    Yamani, Z.; Akhavan, M.

    1997-10-01

    An extensive study of magnetic, electrical transport, and structural properties of the normal and superconducting states of Gd1-xPrxBa2Cu3O7-y (GdPr-123) are presented. Ceramic compounds have been synthesized by the solid-state reaction technique, and characterized by x-ray-diffraction, scanning-electron-microscopy, thermogravimetric, and differential-thermal analyses. The superconducting transition temperature is reduced with increasing Pr content x in a nonlinear manner, in contrast to Abrikosov-Gor'kov pair-breaking theory. Magnetic susceptibility measurements show that the nominal Pr valence is 3.86+, independently of x. A metal-insulator transition is observed at xcr~0.45, similar to that in the oxygen-deficient RBa2Cu3O7-y (R-123) system. Based on this resemblance, we suggest that both Pr doping and oxygen deficiency act through the same mechanism. Hence, the environment surrounding the CuO2 layers is important to high-Tc superconductivity (HTSC). In this sense, HTSC cannot completely be a two-dimentional feature. A chain-plane-correlation effect is plausible.

  16. Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

    Science.gov (United States)

    Zhu, X. P.; Zhang, Z. C.; Pushkarev, A. I.; Lei, M. K.

    2016-01-01

    High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200-300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

  17. Ion beam enhancement in magnetically insulated ion diodes for high-intensity pulsed ion beam generation in non-relativistic mode

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, X. P. [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China); Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Zhang, Z. C.; Lei, M. K., E-mail: surfeng@dlut.edu.cn [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Pushkarev, A. I. [Surface Engineering Laboratory, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Laboratory of Beam and Plasma Technology, High Technologies Physics Institute, Tomsk Polytechnic University, 30, Lenin Ave, 634050 Tomsk (Russian Federation)

    2016-01-15

    High-intensity pulsed ion beam (HIPIB) with ion current density above Child-Langmuir limit is achieved by extracting ion beam from anode plasma of ion diodes with suppressing electron flow under magnetic field insulation. It was theoretically estimated that with increasing the magnetic field, a maximal value of ion current density may reach nearly 3 times that of Child-Langmuir limit in a non-relativistic mode and close to 6 times in a highly relativistic mode. In this study, the behavior of ion beam enhancement by magnetic insulation is systematically investigated in three types of magnetically insulated ion diodes (MIDs) with passive anode, taking into account the anode plasma generation process on the anode surface. A maximal enhancement factor higher than 6 over the Child-Langmuir limit can be obtained in the non-relativistic mode with accelerating voltage of 200–300 kV. The MIDs differ in two anode plasma formation mechanisms, i.e., surface flashover of a dielectric coating on the anode and explosive emission of electrons from the anode, as well as in two insulation modes of external-magnetic field and self-magnetic field with either non-closed or closed drift of electrons in the anode-cathode (A-K) gap, respectively. Combined with ion current density measurement, energy density characterization is employed to resolve the spatial distribution of energy density before focusing for exploring the ion beam generation process. Consistent results are obtained on three types of MIDs concerning control of neutralizing electron flows for the space charge of ions where the high ion beam enhancement is determined by effective electron neutralization in the A-K gap, while the HIPIB composition of different ion species downstream from the diode may be considerably affected by the ion beam neutralization during propagation.

  18. Magnetic ordering in Ho-doped Bi{sub 2}Te{sub 3} topological insulator

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, A.I.; Van der Laan, G.; Hesjedal, T. [Magnetic Spectroscopy Group, Diamond Light Source, Didcot (United Kingdom); Harrison, S.E. [Department of Physics, Clarendon Laboratory, University of Oxford (United Kingdom); Department of Electrical Engineering, Stanford University, Stanford, CA (United States); Collins-McIntyre, L.J. [Department of Physics, Clarendon Laboratory, University of Oxford (United Kingdom)

    2016-06-15

    We investigate the magnetic properties of Ho-doped Bi{sub 2}Te{sub 3} thin films grown by molecular beam epitaxy. Analysis of the polarized X-ray absorption spectra at the Ho M{sub 5} absorption edge gives an effective 4f magnetic moment which is ∝45% of the Hund's rule ground state value. X-ray magnetic circular dichroism (XMCD) shows no significant anisotropy, which suggests that the reduced spin moment is not due to the crystal field effects, but rather the presence of non-magnetic or antiferromagnetic Ho sites. Extrapolating the temperature dependence of the XMCD measured in total electron yield and fluorescence yield mode in a field of 7 T gives a Curie-Weiss temperature of and vartheta;{sub CW} ∼ -30 K, which suggests antiferromagnetic ordering, in contrast to the paramagnetic behavior observed with SQUID magnetometry. From the anomaly of the XMCD signal at low temperatures, a Neel temperature T{sub N} between 10 K and 25 K is estimated. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Electric control of emergent magnonic spin current and dynamic multiferroicity in magnetic insulators at finite temperatures

    Science.gov (United States)

    Wang, Xi-guang; Chotorlishvili, L.; Guo, Guang-hua; Berakdar, J.

    2018-04-01

    Conversion of thermal energy into magnonic spin currents and/or effective electric polarization promises new device functionalities. A versatile approach is presented here for generating and controlling open circuit magnonic spin currents and an effective multiferroicity at a uniform temperature with the aid of spatially inhomogeneous, external, static electric fields. This field applied to a ferromagnetic insulator with a Dzyaloshinskii-Moriya type coupling changes locally the magnon dispersion and modifies the density of thermally excited magnons in a region of the scale of the field inhomogeneity. The resulting gradient in the magnon density can be viewed as a gradient in the effective magnon temperature. This effective thermal gradient together with local magnon dispersion result in an open-circuit, electric field controlled magnonic spin current. In fact, for a moderate variation in the external electric field the predicted magnonic spin current is on the scale of the spin (Seebeck) current generated by a comparable external temperature gradient. Analytical methods supported by full-fledge numerics confirm that both, a finite temperature and an inhomogeneous electric field are necessary for this emergent non-equilibrium phenomena. The proposal can be integrated in magnonic and multiferroic circuits, for instance to convert heat into electrically controlled pure spin current using for example nanopatterning, without the need to generate large thermal gradients on the nanoscale.

  20. Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

    International Nuclear Information System (INIS)

    Zhu, X. P.; Dong, Z. H.; Han, X. G.; Xin, J. P.; Lei, M. K.

    2007-01-01

    Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation

  1. A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    R.D. Woolley

    2009-05-29

    A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.

  2. A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Robert D. Woolley

    2009-06-11

    A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.

  3. A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks

    International Nuclear Information System (INIS)

    Woolley, R.D.

    2009-01-01

    A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress

  4. A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks

    International Nuclear Information System (INIS)

    Woolley, Robert D.

    2009-01-01

    A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.

  5. Calculation of electromagnetic constitutive parameters of insulating magnetic materials with conducting inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Kuster, E.; Moore, R.; Lust, L.; Kemper, P. [Georgia Inst. of Tech., Atlanta, GA (United States)

    1996-12-31

    A Method of Moments (MoM) electromagnetic model of percolating conducting films was applied to calculate the effective parameters of the composite formed by conducting inclusions placed within a dispersive magnetic but nondispersive dielectric matrix. The MoM calculations demonstrate a coupling between the magnetic properties of the matrix and the effective composite permittivity and frequency dispersion of the composite. The coupling of permittivity and permeability is observed near the percolation threshold of the composite and for high conductivity inclusions. The prediction agrees with physical expectations since near percolation the conduction correlation length dominates the effective permittivity of the composite and this correlation length is determined by both the permittivity and permeability of the composite.

  6. Structural analysis of the ITER EDA magnet system

    International Nuclear Information System (INIS)

    Titus, P.H.

    1995-01-01

    The most recent design of the ITER magnet system is easier to assemble and is expected to be more conventionally manufactured. A stainless steel case with pancake wound plates replaces the earlier poloidally wrapped plate Toroidal Field (TF) coil design. The number of TF coils has been reduced from 24 to 20 to ease access. The price for these improvements has been an increase in radial build of the TF coil, and a reallocation of space within the reactor. The TF and central solenoid (CS) are still bucked, making their interface an important area to simulate in structural models. Out-of-plane (OOP) forces are no longer supported by keys between TF legs. The TF case is strong enough to support most of the load when, it in turn, is supported by additional external structures. The most significant of these structures are the upper and lower crowns. A fluted torque shell on the outside of the CS provides a bearing surface for the TF and this along with the CS, and the TF inner legs, takes the global twist applied to the central column of the machine. A US Home team contribution has been a large scale global finite element model which addresses details of construction, and results of this model are presented. Cyclic case bending, torque shell shear, CS shear, the effects of assembly gaps, are presented. The case supports a large portion of the OOP loading, and the possibility of removal or simplifications in the OOP structures is discussed. CS Shear stresses from local conductor behavior are combined with the shears from the global behavior and the total shear is compared with the insulation shear allowable used in the ITER EDA. A smaller structural model has been used to simulate multiple pulse frictional effects, and results of this model are shown

  7. Ion diode performance on a positive polarity inductive voltage adder with layered magnetically insulated transmission line flow

    International Nuclear Information System (INIS)

    Hinshelwood, D. D.; Schumer, J. W.; Allen, R. J.; Commisso, R. J.; Jackson, S. L.; Murphy, D. P.; Phipps, D.; Swanekamp, S. B.; Weber, B. V.; Ottinger, P. F.; Apruzese, J. P.; Cooperstein, G.; Young, F. C.

    2011-01-01

    A pinch-reflex ion diode is fielded on the pulsed-power machine Mercury (R. J. Allen, et al., 15th IEEE Intl. Pulsed Power Conf., Monterey, CA, 2005, p. 339), which has an inductive voltage adder (IVA) architecture and a magnetically insulated transmission line (MITL). Mercury is operated in positive polarity resulting in layered MITL flow as emitted electrons are born at a different potential in each of the adder cavities. The usual method for estimating the voltage by measuring the bound current in the cathode and anode of the MITL is not accurate with layered flow, and the interaction of the MITL flow with a pinched-beam ion diode load has not been studied previously. Other methods for determining the diode voltage are applied, ion diode performance is experimentally characterized and evaluated, and circuit and particle-in-cell (PIC) simulations are performed. Results indicate that the ion diode couples efficiently to the machine operating at a diode voltage of about 3.5 MV and a total current of about 325 kA, with an ion current of about 70 kA of which about 60 kA is proton current. It is also found that the layered flow impedance of the MITL is about half the vacuum impedance.

  8. Magnetism and the low-energy electronic structure of Mott insulators K{sub 2}CoF{sub 4} and SrMnO{sub 3} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Nalecz, D.M., E-mail: sfnalecz@cyf-kr.edu.pl [Institute of Physics, Pedagogical University, 30-084, Krakow (Poland); Radwanski, R.J. [Institute of Physics, Pedagogical University, 30-084, Krakow (Poland); Center of Solid State Physics, S" n" t Filip 5, 31-150, Krakow (Poland); Ropka, Z. [Center of Solid State Physics, S" n" t Filip 5, 31-150, Krakow (Poland)

    2016-09-01

    For Mott insulators, K{sub 2}CoF{sub 4} and SrMnO{sub 3}, we have calculated, in the purely ionic model, the low-energy electronic structure both in the paramagnetic and magnetic state as well as zero-temperature magnetic moment, its direction and its temperature dependence. We have calculated the octahedral crystal-field strength 10Dq to be 0.98 and 2.25 eV. We claim that for an adequate theoretical description of magnetic properties even small local distortions and the intra-atomic relativistic spin-orbit coupling have to be taken into account. Our studies have revealed a strong interplay of the magnetism, the orbital moment in particular, with the local crystallographic structure. The calculated orbital moment in K{sub 2}CoF{sub 4} is very large, 1.06 μ{sub B}, giving 30% contribution to the total moment - this result points the necessity to “unquench” the orbital magnetism in 3d compounds. We consistently described magnetic and some optical properties of these compounds, containing atoms with incomplete 3d shell, in agreement with their insulating ground state. - Highlights: • The octahedral crystal-field 10Dq amounts to 0.98 and 2.25 eV in K{sub 2}CoF{sub 4} and SrMnO{sub 3}. • The low-energy electronic structures in the magnetic state is displayed. • There is a strong interplay of the magnetism and the local crystal structure. • Temperature dependence of the Mn{sup 4+}- ion magnetic moment has been described. • Relativistic spin-orbit coupling is indispensable for description of 3d magnetism.

  9. Inferring condition-specific targets of human TF-TF complexes using ChIP-seq data.

    Science.gov (United States)

    Yang, Chia-Chun; Chen, Min-Hsuan; Lin, Sheng-Yi; Andrews, Erik H; Cheng, Chao; Liu, Chun-Chi; Chen, Jeremy J W

    2017-01-10

    Transcription factors (TFs) often interact with one another to form TF complexes that bind DNA and regulate gene expression. Many databases are created to describe known TF complexes identified by either mammalian two-hybrid experiments or data mining. Lately, a wealth of ChIP-seq data on human TFs under different experiment conditions are available, making it possible to investigate condition-specific (cell type and/or physiologic state) TF complexes and their target genes. Here, we developed a systematic pipeline to infer Condition-Specific Targets of human TF-TF complexes (called the CST pipeline) by integrating ChIP-seq data and TF motifs. In total, we predicted 2,392 TF complexes and 13,504 high-confidence or 127,994 low-confidence regulatory interactions amongst TF complexes and their target genes. We validated our predictions by (i) comparing predicted TF complexes to external TF complex databases, (ii) validating selected target genes of TF complexes using ChIP-qPCR and RT-PCR experiments, and (iii) analysing target genes of select TF complexes using gene ontology enrichment to demonstrate the accuracy of our work. Finally, the predicted results above were integrated and employed to construct a CST database. We built up a methodology to construct the CST database, which contributes to the analysis of transcriptional regulation and the identification of novel TF-TF complex formation in a certain condition. This database also allows users to visualize condition-specific TF regulatory networks through a user-friendly web interface.

  10. Magnetic interference patterns in 0-pi superconductor/insulator/ferromagnet/superconductor Josephson junctions: Effects of asymmetry between 0 and pi regions

    OpenAIRE

    Kemmler, M.; Weides, M.; Goldobin, E.; Weiler, M.; Opel, M.; Goennenwein, S.T.B.; Vasenko, A.S.; Golubov, A.A.; Kohlstedt, H.; Koelle, D.; Kleiner, R.

    2010-01-01

    We present a detailed analysis of the dependence of the critical current I-c on an in-plane magnetic field B of 0, pi, and 0-pi superconductor-insulator-ferromagnet-superconductor Josephson junctions. I-c(B) of the 0 and the pi junction closely follows a Fraunhofer pattern, indicating a homogeneous critical current density j(c)(x). The maximum of I-c(B) is slightly shifted along the field axis, pointing to a small remanent in-plane magnetization of the F-layer along the field axis. I-c(B) of ...

  11. Experiments with all-Kapton insulation and axial prestress in 1.8 m-long SSC R ampersand D magnets

    International Nuclear Information System (INIS)

    Wanderer, P.; Anerella, M.; Cottingham, G.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Herrera, J.; Kahn, S.; Kelly, E.; Meade, A.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Rohrer, E.; Sampson, W.; Shutt, R.; Thompson, P.; Willen, E.; Goodzeit, C.; Radusewicz, P.

    1991-01-01

    Several 1.8 m-long magnets have been built to evaluate possible variations in the design of the SSC collider dipoles. Except for length and the parameters being tested, these models have the features of 40 mm aperture collider dipoles, which are based on a two-layer cosine theta coil. In these magnets, we have tested all-Kapton cable insulation and the effects of changes in the axial coil prestress. Construction details and test results for quenching, field harmonics, and coil loading are reported. 5 refs., 7 figs

  12. Numerical study of a magnetically insulated front-end channel for a neutrino factory

    Directory of Open Access Journals (Sweden)

    Diktys Stratakis

    2011-01-01

    Full Text Available A neutrino factory, which can deliver an intense flux of ∼10^{21} neutrinos per year from a multi-GeV stored muon beam, is seemingly the ideal tool for studying neutrino oscillations and CP violations for leptons. The front end of this facility plays a critical role in determining the number of muons that can be accepted by the downstream accelerators. Delivering peak performance requires transporting the muon beams through long sections of a beam channel containing high-gradient rf cavities and strong focusing solenoids. Here, we propose a novel scheme to improve the performance of the cavities, thereby increasing the number of muons within the acceptance of the accelerator chain. The key element of our new scheme is to apply a tangential magnetic field to the rf surfaces, thus forcing any field-emitted electrons to return to the surface before gaining enough energy to damage the cavity. We incorporate this idea into a new lattice design for a neutrino factory, and detail its performance numerically. Although our proposed front-end channel requires more rf power than conventional pillbox designs, it provides enough beam cooling and muon production to be a feasible option for a neutrino factory.

  13. Final Report: Stability and Novel Properties of Magnetic Materials and Ferromagnet / Insulator Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Voyles, Paul M. [Univ. of Wisconsin, Madison, WI (United States); Chang, Y. Austin [Univ. of Wisconsin, Madison, WI (United States)

    2013-07-24

    We report investigations of the synthesis, structure, and properties of new materials for spintronic applications integrated onto silicon substrates. Our primary focus is materials with very high, negative, intrinsic spin polarization of the density of states at the Fermi level. We have developed a new synthesis method for Fe3O4 thin films through selective oxidation of Fe, resulting in smooth, low-defect density films. We have synthesized Fe4N films and shown that they preferentially oxidize to Fe3O4. When integrated into magnetic tunnel junctions consisting of Fe4N / AlOx / Fe, oxidation at the Fe4N / AlOx interface creates Fe3O4, leading to negative tunneling magnetoresistance (TMR). Oxidation of Fe in nominally symmetric CoFe / AlOx / CoFe also produces Fe3O4 and negative TMR under selected oxidation conditions.

  14. Improved charge neutralization method for depth profiling of bulk insulators using O2+ primary beam on a magnetic sector SIMS instrument

    International Nuclear Information System (INIS)

    Pivovarov, A.L.; Stevie, F.A.; Griffis, D.P.

    2004-01-01

    Use of electrons for charge neutralization during positive secondary ion SIMS analysis of insulators has typically been achieved using coincident primary ion and electron beams. The normal incidence electron gun on CAMECA magnetic sector SIMS instruments can effectively eliminate sample charging during analysis of thin insulating films if the electron energy is sufficient to penetrate the film. However, positive secondary ion SIMS bulk insulator analysis using this instrument can be difficult, especially if high sputtering rates are required. A neutralization method has been developed utilizing electron beam impact of a region adjacent to the sputtered area. Prior to analysis, the surface of the sample is coated with gold which provides a conductive surface layer and which has a high secondary and backscattered electron yield. Results have been obtained showing excellent neutralization for a variety of bulk insulators including glass, silica, alumina, and lithium niobate. Sputtering rates exceeding 2 nm/s have been achieved in bulk silica. The technique should be applicable to minerals and possibly for other materials in cases where the analyzed area cannot be directly irradiated with an electron beam

  15. Experimental study on magnetically insulated transmission line electrode surface evolution process under MA/cm current density

    International Nuclear Information System (INIS)

    Zhang, PengFei; Qiu, Aici; Hu, Yang; Yang, HaiLiang; Sun, Jiang; Wang, Liangping; Cong, Peitian

    2016-01-01

    The design of high-current density magnetically insulated transmission line (MITL) is a difficult problem of current large-scale Z-pinch device. In particular, a thorough understanding of the MITL electrode surface evolution process under high current density is lacking. On the “QiangGuang-I” accelerator, the load area possesses a low inductance short-circuit structure with a diameter of 2.85 mm at the cathode, and three reflux columns with a diameter of 3 mm and uniformly distributed circumference at the anode. The length of the high density MITL area is 20 mm. A laser interferometer is used to assess and analyze the state of the MITL cathode and anode gap, and their evolution process under high current density. Experimental results indicate that evident current loss is not observed in the current density area at pulse leading edge, and peak when the surface current density reaches MA/cm. Analysis on electrode surface working conditions indicates that when the current leading edge is at 71.5% of the peak, the total evaporation of MITL cathode structure can be realized by energy deposition caused by ohmic heating. The electrode state changes, and diffusion conditions are reflected in the laser interferometer image. The MITL cathode area mainly exists in metal vapor form. The metal vapor density in the cathode central region is higher than the upper limit of laser penetration density (∼4 × 10 21 /cm 3 ), with an expansion velocity of ∼0.96 km/s. The metal vapor density in the electrode outer area may lead to evident distortion of fringes, and its expansion velocity is faster than that in the center area (1.53 km/s).

  16. Fabrication of new joints for SST-1 TF coil winding packs

    International Nuclear Information System (INIS)

    Prasad, Upendra; Sharma, A.N.; Patel, Dipak; Doshi, Kalpesh; Khristi, Yohan; Varmora, Pankaj; Chauhan, Pradeep; Jadeja, S.J.; Gupta, Pratibha; Pradhan, S.

    2013-01-01

    Highlights: • We have carried out work related with sub-nanoohm joints for superconducting Tokamak winding packs. • We have established fine tune QA/QC procedures for sub-nanoohm joints fabrication. • We have optimised welding parameters for cable in conduit conductors for fusion relevant magnets. • We have established precised measurement data acquisition system for low resistance measurements at cryogenic temperature. -- Abstract: The Toroidal Field (TF) magnet system of SST-1 has sixteen NbTi/Cu based coils with about one hundred Inter-Pancake (IP) and Inter-Coil (IC) joints. New box type helium leak tight, low DC resistance joints have been designed, fabricated and tested at 5 K temperature and 10 kA DC transport current. The prototype of this joint has been validated in laboratory as well as on spare TF coil winding pack. Moreover, the performance of these joints has been realised and validated on actual sixteen TF winding packs, the joint resistance of ∼0.5 nΩ repeatedly measured on hundreds of IP joints. The quality of terminations and joints was ensured at various stages of fabrication. The quality of joint box material was ensured by visual inspection, chemical analysis, radiography test, ultrasonic test, eddy current test, etc. This paper describes joint design drivers, joint design detail, prototype joint fabrication processes, quality assurance (QA)/quality control (QC) adopted during prototype and actual joint fabrication process, joint resistance measurement on actual TF coils and analysis of measured joint resistance in detail

  17. Extending TF1: Argument parsing, function composition, and vectorization

    CERN Document Server

    Tsang Mang Kin, Arthur Leonard

    2017-01-01

    In this project, we extend the functionality of the TF1 function class in root. We add argument parsing, making it possible to freely pass variables and parameters into pre-defined and user-defined functions. We also introduce a syntax to use certain compositions of functions, namely normalized sums and convolutions, directly in TF1. Finally, we introduce some simple vectorization functionality to TF1 and demonstrate the potential to speed up parallelizable computations.

  18. Study of heat transfer in superconducting cable electrical insulation of accelerator magnet cooled by superfluid helium; Etude des transferts de chaleur dans les isolations electriques de cables supraconducteurs d'aimant d'accelerateur refroidi par helium superfluide

    Energy Technology Data Exchange (ETDEWEB)

    Baudouy, B

    1996-10-04

    Heat transfer studies of electrical cable insulation in superconducting winding are of major importance for stability studies in superconducting magnets. This work presents an experimental heat transfer study in superconducting cables of Large Hadron Collider dipoles cooled by superfluid helium and submitted to volume heat dissipation due to beam losses. For NbTi magnets cooled by superfluid helium the most severe heat barrier comes from the electrical insulation of the cables. Heat behaviour of a winding is approached through an experimental model in which insulation characteristics can be modified. Different tests on insulation patterns show that heat transfer is influenced by superfluid helium contained in insulation even for small volume of helium (2 % of cable volume). Electrical insulation can be considered as a composite material made of a solid matrix with a helium channels network which cannot be modelled easily. This network is characterised by another experimental apparatus which allows to study transverse and steady-state heat transfer through an elementary insulation pattern. Measurements in Landau regime ({delta}T{approx}10{sup -5} to 10{sup -3} K) and in Gorter-Mellink regime ({delta}T>10{sup -3} K) and using assumptions that helium thermal paths and conduction in the insulation are decoupled allow to determine an equivalent channel area (10{sup -6} m{sup 2}) and an equivalent channel diameter (25 {mu}). (author)

  19. Photonic Floquet topological insulators

    Science.gov (United States)

    Rechtsman, Mikael C.; Zeuner, Julia M.; Plotnik, Yonatan; Lumer, Yaakov; Podolsky, Daniel; Dreisow, Felix; Nolte, Stefan; Segev, Mordechai; Szameit, Alexander

    2013-09-01

    Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on the surface. In two dimensions, surface electrons in topological insulators do not scatter despite defects and disorder, providing robustness akin to superconductors. Topological insulators are predicted to have wideranging applications in fault-tolerant quantum computing and spintronics. Recently, large theoretical efforts were directed towards achieving topological insulation for electromagnetic waves. One-dimensional systems with topological edge states have been demonstrated, but these states are zero-dimensional, and therefore exhibit no transport properties. Topological protection of microwaves has been observed using a mechanism similar to the quantum Hall effect, by placing a gyromagnetic photonic crystal in an external magnetic field. However, since magnetic effects are very weak at optical frequencies, realizing photonic topological insulators with scatterfree edge states requires a fundamentally different mechanism - one that is free of magnetic fields. Recently, a number of proposals for photonic topological transport have been put forward. Specifically, one suggested temporally modulating a photonic crystal, thus breaking time-reversal symmetry and inducing one-way edge states. This is in the spirit of the proposed Floquet topological insulators, where temporal variations in solidstate systems induce topological edge states. Here, we propose and experimentally demonstrate the first external field-free photonic topological insulator with scatter-free edge transport: a photonic lattice exhibiting topologically protected transport of visible light on the lattice edges. Our system is composed of an array of evanescently coupled helical waveguides arranged in a graphene-like honeycomb lattice. Paraxial diffraction of light is described by a Schrödinger equation where the propagation coordinate acts as `time'. Thus the waveguides

  20. Selective-area growth and magnetic characterization of MnAs/AlGaAs nanoclusters on insulating Al2O3 layers crystallized on Si(111) substrates

    Science.gov (United States)

    Sakita, Shinya; Hara, Shinjiro; Elm, Matthias T.; Klar, Peter J.

    2016-01-01

    We report on selective-area metal-organic vapor phase epitaxy and magnetic characterization of coupled MnAs/AlGaAs nanoclusters formed on thin Al2O3 insulating layers crystallized on Si(111) substrates. Cross-sectional transmission electron microscopy reveals that poly-crystalline γ-Al2O3 grains are formed after an annealing treatment of the amorphous Al2O3 layers deposited by atomic layer deposition on Si(111) substrates. The ⟨111⟩ direction of the γ-Al2O3 grains tends to be oriented approximately parallel to the ⟨111⟩ direction of the Si substrate. We observe that hexagonal MnAs nanoclusters on AlGaAs buffer layers grown by selective-area metal-organic vapor phase epitaxy on partially SiO2-masked Al2O3 insulator crystallized on Si(111) substrates are oriented with the c-axis along the ⟨111⟩ direction of the substrates, but exhibit a random in-plane orientation. A likely reason is the random orientation of the poly-crystalline γ-Al2O3 grains in the Al2O3 layer plane. Magnetic force microscopy studies at room temperature reveal that arrangements of coupled MnAs nanoclusters exhibit a complex magnetic domain structure. Such arrangements of coupled MnAs nanoclusters may also show magnetic random telegraph noise, i.e., jumps between two discrete resistance levels, in a certain temperature range, which can be explained by thermally activated changes of the complex magnetic structure of the nanocluster arrangements.

  1. Cellulose Insulation

    Science.gov (United States)

    1980-01-01

    Fire retardant cellulose insulation is produced by shredding old newspapers and treating them with a combination of chemicals. Insulating material is blown into walls and attics to form a fiber layer which blocks the flow of air. All-Weather Insulation's founders asked NASA/UK-TAP to help. They wanted to know what chemicals added to newspaper would produce an insulating material capable of meeting federal specifications. TAP researched the query and furnished extensive information. The information contributed to successful development of the product and helped launch a small business enterprise which is now growing rapidly.

  2. Thermal insulator

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, R.; Asada, Y.; Matsuo, Y.; Mikoda, M.

    1985-07-16

    A thermal insulator comprises an expanded resin body having embedded therein an evacuated powder insulation portion which consists of fine powder and a container of film-like plastics or a film-like composite of plastics and metal for enclosing the powder. The resin body has been expanded by a Freon gas as a blowing agent. Since a Freon gas has a larger molecular diameter than the constituent gases of air, it is less likely to permeate through the container than air. Thus present invention provides a novel composite insulator which fully utilizes the benefits of vacuum insulation without necessitating a strong and costly material for a vacuum container.

  3. Electronic structure and x-ray magnetic circular dichroism in Mn-doped topological insulators Bi2Se3 and Bi2Te3

    Science.gov (United States)

    Antonov, V. N.; Bekenov, L. V.; Uba, S.; Ernst, A.

    2017-12-01

    We studied the structural, electronic, and magnetic properties of Mn-doped topological insulators Bi2Se3 and Bi2Te3 within the density-functional theory (DFT) using the generalized gradient approximation (GGA) in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. The x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism at the Mn K and L2 ,3 edges were investigated theoretically from first principles. The calculated results are in good agreement with experimental data. The complex fine structure of the Mn L2 ,3 XAS in Mn-doped Bi2Se3 and Bi2Te3 was found to be not compatible with a pure Mn3 + valency state. Its interpretation demands mixed valent states. The theoretically calculated x-ray emission spectra at the Mn K and L2 ,3 edges are also presented and analyzed.

  4. Structural, magnetic, and electronic properties of GdTiO{sub 3} Mott insulator thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Grisolia, M. N.; Bruno, F. Y.; Sando, D.; Jacquet, E.; Barthélémy, A.; Bibes, M., E-mail: manuel.bibes@thalesgroup.com [Unité Mixte de Physique, CNRS-Thales, 1 Av. Augustin Fresnel, Campus de l' Ecole Polytechnique, 91120 Palaiseau, France and Université Paris-Sud, 91405 Orsay (France); Zhao, H. J. [Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Chen, X. M. [Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Bellaiche, L. [Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States)

    2014-10-27

    We report on the optimization process to synthesize epitaxial thin films of GdTiO{sub 3} on SrLaGaO{sub 4} substrates by pulsed laser deposition. Optimized films are free of impurity phases and are fully strained. They possess a magnetic Curie temperature T{sub C} = 31.8 K with a saturation magnetization of 4.2 μ{sub B} per formula unit at 10 K. Transport measurements reveal an insulating response, as expected. Optical spectroscopy indicates a band gap of ∼0.7 eV, comparable to the bulk value. Our work adds ferrimagnetic orthotitanates to the palette of perovskite materials for the design of emergent strongly correlated states at oxide interfaces using a versatile growth technique such as pulsed laser deposition.

  5. Insulator applications in a Tokamak reactor

    International Nuclear Information System (INIS)

    Leger, D.

    1986-06-01

    Insulators, among which insulators ceramics, have great potential applications in fusion reactors. They will be used for all plasma-facing components as protection and, magnetic fusion devices being subject to large electrical currents flowing in any parts of the device, for their electrical insulating properties

  6. Thermal insulation

    International Nuclear Information System (INIS)

    Pinsky, G.P.

    1977-01-01

    Thermal insulation for vessels and piping within the reactor containment area of nuclear power plants is disclosed. The thermal insulation of this invention can be readily removed and replaced from the vessels and piping for inservice inspection, can withstand repeated wettings and dryings, and can resist high temperatures for long periods of time. 4 claims, 3 figures

  7. AC loss, interstrand resistance and mechanical properties of prototype EU DEMO TF conductors up to 30 000 load cycles

    NARCIS (Netherlands)

    Yagotyntsev, K.; Nijhuis, A.

    2018-01-01

    Two prototype Nb3Sn cable-in-conduit conductors conductors were designed and manufactured for the toroidal field (TF) magnet system of the envisaged European DEMO fusion reactor. The AC loss, contact resistance and mechanical properties of two sample conductors were tested in the Twente Cryogenic

  8. Magnet Design Considerations for Fusion Nuclear Science Facility

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Y. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kessel, C. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); El-Guebaly, L. [Univ. of Wisconsin, Madison, WI (United States) Fusion Technology Institute; Titus, P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

    2016-06-01

    The Fusion Nuclear Science Facility (FNSF) is a nuclear confinement facility that provides a fusion environment with components of the reactor integrated together to bridge the technical gaps of burning plasma and nuclear science between the International Thermonuclear Experimental Reactor (ITER) and the demonstration power plant (DEMO). Compared with ITER, the FNSF is smaller in size but generates much higher magnetic field, i.e., 30 times higher neutron fluence with three orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5 T at the plasma center with a plasma major radius of 4.8 m and a minor radius of 1.2 m and a peak field of 15.5 T on the toroidal field (TF) coils for the FNSF. Both low-temperature superconductors (LTS) and high-temperature superconductors (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology. The higher magnetic field can be achieved by using the high-performance ternary restacked-rod process Nb3Sn strands for TF magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high-aspect-ratio rectangular CICC design are evaluated for FNSF magnets, but low-activation-jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. The material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.

  9. Tokamak Physics EXperiment (TPX): Toroidal field magnet design, development and manufacture. SDRL 46, CPDR review package. Volume 6

    Energy Technology Data Exchange (ETDEWEB)

    Weber, C.M. [Babcock and Wilcox Co., Lynchburg, VA (United States)

    1995-08-18

    This preliminary design reviews the overall design package for the magnet system. It is mostly presented in viewgraphs. The lengthy presentation took up two full days. Sections are given on TF SDD, TF magnet specifications, TF interface definition, drawing tree and design control, winding pack design, manufacturing, coil setup for VPI, TPX TF magnet assembly, TF materials and processes, quality assurance and test requirements, coil verification testing, TPX acceptance tools, and planning tools.

  10. Magnet systems for the International Thermonuclear Experimental Reactor

    International Nuclear Information System (INIS)

    Henning, C.D.; Miller, J.R.

    1988-01-01

    The definition phase for the International Thermonuclear Experimental Reactor (ITER) has been nearly completed, thus beginning a three-year design effort by teams from the European Community (EC), Japan, US, and USSR. Preliminary parameters for the superconducting magnet system have been established to guide more detailed design work. Radiation tolerance of the superconductors and insulators has been important because it sets requirements for the neutron-shield dimension and sensitively influences reactor size. Major levels of mechanical stress appear in the structural cases of the inboard legs of the toroidal-field (TF) coils. The winding packs of the TF coils include significant fractions of steel that provide support against in-plane separating loads, but they offer little support against out-of-plane loads unless shear-bonding of the conductors can be maintained. Heat removal from nuclear and ac loads has not limited the fundamental design, but it has nonnegligible economic consequences. 3 refs., 3 figs., 5 tabs

  11. Magnet systems for the International Thermonuclear Experimental Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Henning, C.D.; Miller, J.R.

    1988-09-22

    The definition phase for the International Thermonuclear Experimental Reactor (ITER) has been nearly completed, thus beginning a three-year design effort by teams from the European Community (EC), Japan, US, and USSR. Preliminary parameters for the superconducting magnet system have been established to guide more detailed design work. Radiation tolerance of the superconductors and insulators has been important because it sets requirements for the neutron-shield dimension and sensitively influences reactor size. Major levels of mechanical stress appear in the structural cases of the inboard legs of the toroidal-field (TF) coils. The winding packs of the TF coils include significant fractions of steel that provide support against in-plane separating loads, but they offer little support against out-of-plane loads unless shear-bonding of the conductors can be maintained. Heat removal from nuclear and ac loads has not limited the fundamental design, but it has nonnegligible economic consequences. 3 refs., 3 figs., 5 tabs.

  12. Superconducting magnet systems for the ANL EPR design

    International Nuclear Information System (INIS)

    Turner, L.R.; Wang, S.T.; Kim, S.H.; Huang, Y.C.; Smith, R.P.

    1978-01-01

    The magnet systems for the current Argonne experimental power reactor (EPR) design build on the earlier designs but incorporate a number of improvements. The toroidal field (TF) coil system consists of 16 coils of the constant tension shape, with NbTi, copper, and stainless steel as superconductor, stabilizer, and support material respectively. They are designed for 10 T operation at 3.7 K or 9 T operation at 4.2 K. Two changes from earlier designs permit a saving in material requirements. The coils are wound with the conductor in precompression and the support material in pretension so that when the coils are energized, the stainless steel experiences a stress of 60,000 psi while the copper stress does not exceed 15,000 psi. Both the copper and NbTi are graded, with higher current densities where magnetic and radiation effects are smaller. The ohmic heating (OH) coil system consists of a central solenoid plus ten other coils, all located outside the TF coils for ease of maintenance. The NbTi-copper coils are cryostable and operate at 4.2 K. The solenoid is segmented, with rings of insulation between segments to transfer the centering force from the TF coils to an insulating cylinder inside the OH solenoid. Locating the OH solenoid inside the support cylinder plus raising the central field to 8 T, enables the OH system to develop more volt-seconds than the earlier designs, even though the plasma major radius is smaller. The superconducting equilibrium field coils, also outside the TF coils, provide the field pattern required for a D-shaped plasma

  13. TF Inner Leg Space Allocation for Pilot Plant Design Studies

    Energy Technology Data Exchange (ETDEWEB)

    Peter H. Titus and Ali Zolfaghari

    2012-09-06

    A critical design feature of any tokamak is the space taken up by the inner leg of the toroidal field (TF) coil. The radial build needed for the TF inner leg, along with shield thickness , size of the central solenoid and plasma minor radius set the major radius of the machine. The cost of the tokamak core roughly scales with the cube of the major radius. Small reductions in the TF build can have a big impact on the overall cost of the reactor. The cross section of the TF inner leg must structurally support the centering force and that portion of the vertical separating force that is not supported by the outer structures. In this paper, the TF inner leg equatorial plane cross sections are considered. Out-of- Plane (OOP) forces must also be supported, but these are largest away from the equatorial plane, in the inner upper and lower corners and outboard sections of the TF coil. OOP forces are taken by structures that are not closely coupled with the radial build of the central column at the equatorial plane. The "Vertical Access AT Pilot Plant" currently under consideration at PPPL is used as a starting point for the structural, field and current requirements. Other TF structural concepts are considered. Most are drawn from existing designs such as ITER's circular conduits in radial plates bearing on a heavy nose section, and TPX's square conduits in a case, Each of these concepts can rely on full wedging, or partial wedging. Vaulted TF coils are considered as are those with some component of bucking against a central solenoid or bucking post. With the expectation that the pilot plant will be a steady state machine, a static stress criteria is used for all the concepts. The coils are assumed to be superconducting, with the superconductor not contributing to the structural strength. Limit analysis is employed to assess the degree of conservatism in the static criteria as it is applied to a linear elastic stress analysis. TF concepts, and in particular the PPPL AT

  14. Novel Synchronous Linear and Rotatory Micro Motors Based on Polymer Magnets with Organic and Inorganic Insulation Layers

    Directory of Open Access Journals (Sweden)

    Andreas WALDSCHIK

    2008-12-01

    Full Text Available In this work, we report on the development of several synchronous motors with rotatory or linear movements. The synchronous micro motors are brushless DC motors or stepper motors with electrically controlled commutation consisting of a stator and a rotor. The rotor is mounted onto the stator and is adjusted by an integrated guidance. Inside the stator different coil systems are realized, like double layer sector coils or special nested coils. The coil systems can be controlled by three or six phases depending on the operational mode. Furthermore, inorganic insulation layers were used in order to reduce the thickness of the system. By this means four layers of electrical conductors can be realized especially for the 2D devices. The smallest diameter of the rotatory motor is 1 mm and could be successfully driven.

  15. Insulators for fusion applications

    International Nuclear Information System (INIS)

    1987-04-01

    Design studies for fusion devices and reactors have become more detailed in recent years and with this has come a better understanding of requirements and operating conditions for insulators in these machines. Ceramic and organic insulators are widely used for many components of fusion devices and reactors namely: radio frequency (RF) energy injection systems (BeO, Al 2 O 3 , Mg Al 2 O 4 , Si 3 N 4 ); electrical insulation for the torus structure (SiC, Al 2 O 3 , MgO, Mg Al 2 O 4 , Si 4 Al 2 O 2 N 6 , Si 3 N 4 , Y 2 O 3 ); lightly-shielded magnetic coils (MgO, MgAl 2 O 4 ); the toroidal field coil (epoxies, polyimides), neutron shield (B 4 C, TiH 2 ); high efficiency electrical generation; as well as the generation of very high temperatures for high efficiency hydrogen production processes (ZrO 2 and Al 2 O 3 - mat, graphite and carbon - felt). Timely development of insulators for fusion applications is clearly necessary. Those materials to be used in fusion machines should show high resistance to radiation damage and maintain their structural integrity. Now the need is urgent for a variety of radiation resistant materials, but much effort in these areas is required for insulators to be considered seriously by the design community. This document contains 14 papers from an IAEA meeting. It was the objective of this meeting to identify existing problems in analysing various situations of applications and requirements of electrical insulators and ceramics in fusion and to recommend strategies and different stages of implementation. This meeting was endorsed by the International Fusion Research Council

  16. Orbital magnetization of a Mott insulator, V2O3, revealed by resonant x-ray Bragg diffraction

    Science.gov (United States)

    Lovesey, S. W.; Knight, K. S.; Sivia, D. S.

    2002-06-01

    Structure factors calculated for x-ray Bragg diffraction by magnetically ordered vanadium sesquioxide, V2O3, with signal enhancement from the vanadium K-shell resonance, are compared with data gathered in azimuthal-angle scans at space-group forbidden reflections. Diffraction enhanced by a K-shell resonance reveals properties of the orbital magnetization in the valence shell of the resonant ion, whereas other core states, which have two partners because of the spin-orbit interaction, reveal properties of both the spin and orbital magnetization in the valence shell. Agreement on all issues between observed and calculated Bragg intensities support the use of an atomic model for the interpretation of data. The reflections are shown to be purely magnetic, and associated with the orbital magnetic moment and the octupole moment of a vanadium ion. Reflections with a Miller index h even are analyzed to give the canting angle of the magnetic easy axis. Data from the rotated (π'σ) and unrotated (σ'σ) channels of scattering provide an angle consistent with an earlier interpretation of magnetic neutron diffraction. With h odd, diffraction enhanced by an E1 event is forbidden. Intensities enhanced by an E2 event are from anisotropic components of the octupole moment. Analysis of azimuthal-angle scans, with h even and h odd, provides estimates of orbital moments that in the future can be confronted with ab initio calculations of the electronic properties of V2O3. By and large, the complicated pattern of azimuthal-angle scans can be attributed to the low symmetry (monoclinic) structure adopted below the Néel temperatures.

  17. Topological insulators

    CERN Document Server

    Franz, Marcel

    2013-01-01

    Topological Insulators, volume six in the Contemporary Concepts of Condensed Matter Series, describes the recent revolution in condensed matter physics that occurred in our understanding of crystalline solids. The book chronicles the work done worldwide that led to these discoveries and provides the reader with a comprehensive overview of the field. Starting in 2004, theorists began to explore the effect of topology on the physics of band insulators, a field previously considered well understood. However, the inclusion of topology brings key new elements into this old field. Whereas it was

  18. Self-Magnetically Insulated Transmission Line ( SMILE'') a new version for the RADLAC II linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Mazarakis, M.G.; Poukey, J.W.; Shope, S.L.; Frost, C.A.; Pankuch, P.J.; Turman, B.N.; Ramirez, J.J.; Prestwich, K.R.

    1990-01-01

    We present here the SMILE modification of the RADLAC II accelerator which enabled us to produce high quality 12--14 MV, 100 kA beams. It consists of replacing the 40-kA 4-MV beam injector, magnetic vacuum transport and accelerating gaps by a long cathode shank which adds up the voltages of the 8 pulse forming lines. The beam now is produced at the end of the accelerator and is free of all the possible instabilities associated with accelerating gaps and magnetic vacuum transport. Annular beams with {beta}{perpendicular} {le} 0.1 and radius r{sub b} {le} 2 cm are routinely obtained and extracted from a small magnetically immersed foilless electron diode. Results of the experimental evaluation are presented and compared with design parameters and numerical simulation predictions. 6 refs., 7 figs., 1 tab.

  19. Translucent Insulation

    DEFF Research Database (Denmark)

    Rahbek, Jens Eg

    1998-01-01

    Two new types of translucent materials are presented. One is translucent fiber insulation and the other type is a new type of hony-comb made of Celulose-acetat. Data for the materials and calculations of energy savings when using the materials in building envelopes are presented....

  20. Incipient Stator Insulation Fault Detection of Permanent Magnet Synchronous Wind Generators Based on Hilbert–Huang Transformation

    DEFF Research Database (Denmark)

    Wang, Chao; Liu, Xiao; Chen, Zhe

    2014-01-01

    Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree...

  1. Radiation effects on organic insulators for superconducting magnets. Annual progress report for period ending September 30, 1979

    International Nuclear Information System (INIS)

    Coltman, R.R. Jr.; Klabunde, C.E.; Kernohan, R.H.; Long, C.J.

    1979-11-01

    The most recent efforts in a program to study the effects of irradiation near 5 K on organic insulators for fusion reactors have extended the irradiation dose from 2 x 10 9 to 1 x 10 10 rads and have studied additional effects due to fast neutrons. When added to a gamma-ray dose of 2.4 x 10 9 rads, a fast-neutron fluence of 2.4 x 10 20 n/m 2 has little effect upon changes in electrical and mechanical properties. At this dose, present results are in agreement with previous results. At a dose of 1 x 10 10 rads, particle-filled epoxies are at end of life in terms of mechanical strength, while fiberglass-cloth-filled epoxies retain sufficient strength for use. Electrical-resistivity and voltage-breakdown values were reduced in some materials but remained in a usable range. Two sheet-type materials showed excellent stability in their electrical properties. Dimensional stability was generally good, except for one epoxy which showed considerable swelling at the higher dose

  2. Expression of antigen tf and galectin-3 in fibroadenoma.

    Science.gov (United States)

    Gallegos, Itandehui Belem; Pérez-Campos, Eduardo; Martinez, Margarito; Mayoral, Miguel Ángel; Pérez, Laura; Aguilar, Sergio; Zenteno, Edgar; Pina, Maria del Socorro; Hernández, Pedro

    2012-12-24

    Fibroadenomas are benign human breast tumors, characterized by proliferation of epithelial and stromal components of the terminal ductal unit. They may grow, regress or remain unchanged, as the hormonal environment of the patient changes. Expression of antigen TF in mucin or mucin-type glycoproteins and of galectin-3 seems to contribute to proliferation and transformations events; their expression has been reported in ductal breast cancer and in aggressive tumors. Lectin histochemistry, immunohistochemistry, and immunofluorescence were used to examine the expression and distribution of antigen TF and galectin-3. We used lectins from Arachis hypogaea, Artocarpus integrifolia, and Amaranthus lecuocarpus to evaluate TF expression and a monoclonal antibody to evaluate galectin-3 expression. We used paraffin-embedded blocks from 10 breast tissues diagnosed with fibroadenoma and as control 10 healthy tissue samples. Histochemical and immunofluorescence analysis showed positive expression of galectin-3 in fibroadenoma tissue, mainly in stroma, weak interaction in ducts was observed; whereas, in healthy tissue samples the staining was also weak in ducts. Lectins from A. leucocarpus and A. integrifolia specificaly recognized ducts in healthy breast samples, whereas the lectin from A. hypogaea recognized ducts and stroma. In fibroadenoma tissue, the lectins from A. integrifolia, A. Hypogaea, and A. leucocarpus recognized mainly ducts. Our results suggest that expression of antigen TF and galectin-3 seems to participate in fibroadenoma development.

  3. Expression of antigen tf and galectin-3 in fibroadenoma

    Directory of Open Access Journals (Sweden)

    Gallegos Itandehui Belem

    2012-12-01

    Full Text Available Abstract Background Fibroadenomas are benign human breast tumors, characterized by proliferation of epithelial and stromal components of the terminal ductal unit. They may grow, regress or remain unchanged, as the hormonal environment of the patient changes. Expression of antigen TF in mucin or mucin-type glycoproteins and of galectin-3 seems to contribute to proliferation and transformations events; their expression has been reported in ductal breast cancer and in aggressive tumors. Findings Lectin histochemistry, immunohistochemistry, and immunofluorescence were used to examine the expression and distribution of antigen TF and galectin-3. We used lectins from Arachis hypogaea, Artocarpus integrifolia, and Amaranthus lecuocarpus to evaluate TF expression and a monoclonal antibody to evaluate galectin-3 expression. We used paraffin-embedded blocks from 10 breast tissues diagnosed with fibroadenoma and as control 10 healthy tissue samples. Histochemical and immunofluorescence analysis showed positive expression of galectin-3 in fibroadenoma tissue, mainly in stroma, weak interaction in ducts was observed; whereas, in healthy tissue samples the staining was also weak in ducts. Lectins from A. leucocarpus and A. integrifolia specificaly recognized ducts in healthy breast samples, whereas the lectin from A. hypogaea recognized ducts and stroma. In fibroadenoma tissue, the lectins from A. integrifolia, A. Hypogaea, and A. leucocarpus recognized mainly ducts. Conclusions Our results suggest that expression of antigen TF and galectin-3 seems to participate in fibroadenoma development.

  4. Expression of antigen tf and galectin-3 in fibroadenoma

    Science.gov (United States)

    2012-01-01

    Background Fibroadenomas are benign human breast tumors, characterized by proliferation of epithelial and stromal components of the terminal ductal unit. They may grow, regress or remain unchanged, as the hormonal environment of the patient changes. Expression of antigen TF in mucin or mucin-type glycoproteins and of galectin-3 seems to contribute to proliferation and transformations events; their expression has been reported in ductal breast cancer and in aggressive tumors. Findings Lectin histochemistry, immunohistochemistry, and immunofluorescence were used to examine the expression and distribution of antigen TF and galectin-3. We used lectins from Arachis hypogaea, Artocarpus integrifolia, and Amaranthus lecuocarpus to evaluate TF expression and a monoclonal antibody to evaluate galectin-3 expression. We used paraffin-embedded blocks from 10 breast tissues diagnosed with fibroadenoma and as control 10 healthy tissue samples. Histochemical and immunofluorescence analysis showed positive expression of galectin-3 in fibroadenoma tissue, mainly in stroma, weak interaction in ducts was observed; whereas, in healthy tissue samples the staining was also weak in ducts. Lectins from A. leucocarpus and A. integrifolia specificaly recognized ducts in healthy breast samples, whereas the lectin from A. hypogaea recognized ducts and stroma. In fibroadenoma tissue, the lectins from A. integrifolia, A. Hypogaea, and A. leucocarpus recognized mainly ducts. Conclusions Our results suggest that expression of antigen TF and galectin-3 seems to participate in fibroadenoma development. PMID:23265237

  5. TfR Binding Peptide Screened by Phage Display Technology ...

    African Journals Online (AJOL)

    can significantly increase the enrichment of the drug in the target tissue, improve efficacy, and reduce the side effects of drugs [7-9]. The transferrin receptor (TfR) has been reported to be ubiquitously expressed and is over- expressing 100-fold in many tumour cells and brain capillary endothelial cells [10]. Because of.

  6. Unusual negative magnetoresistance in Bi2Se3-ySy topological insulator under perpendicular magnetic field

    Science.gov (United States)

    Singh, Rahul; Gangwar, Vinod K.; Daga, D. D.; Singh, Abhishek; Ghosh, A. K.; Kumar, Manoranjan; Lakhani, A.; Singh, Rajeev; Chatterjee, Sandip

    2018-03-01

    The magneto-transport properties of Bi2Se3-ySy were investigated. Magnetoresistance (MR) decreases with an increase in the S content, and finally, for 7% (i.e., y = 0.21) S doping, the magnetoresistance becomes negative. This negative MR is unusual as it is observed when a magnetic field is applied in the perpendicular direction to the plane of the sample. The magneto-transport behavior shows the Shubnikov-de Haas (SdH) oscillation, indicating the coexistence of surface and bulk states. The negative MR has been attributed to the non-trivial bulk conduction.

  7. Effect of thermal contact between winding pack and casing on thermal behavior of SST-1 TF coil

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, A.K. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)]. E-mail: aksahu@ipr.res.in; Sarkar, B. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Gupta, N.C. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Panchal, P. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Bhattacharya, R. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Tank, J. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Gupta, G. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Shah, N. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Shukla, P. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Singh, M. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Phadke, G. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India); Saxena, Y.C. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2006-11-15

    Active cooling of the casing, which houses the winding pack of the large size superconducting magnet used for magnetic confinement of plasma under a steady state configuration, has been one of the points for debate. Toroidal field (TF) coils of SST-1 consists of six double pancakes of Nb-Ti based cable-in-conduit conductor (CICC), duly impregnated and encased in a tight fit stainless steel casing. In order to validate the cooling configuration of the SST-1 TF magnet system, an experiment has been done on one of the full scale TF coil without having cooling channels for the casing. The experimental results show a distributed temperature profile on the casing ranging from the lowest temperature of 17 K to the highest temperature of 29 K. The data obtained has been analyzed on the basis of thermal contact and thermal resistance. The paper will describe the experimental setup, thermo-hydraulic behavior of the CICC in winding condition and the comparison of experimental results with an empirical analysis.

  8. Proposal for the award of a contract for the supply of polyimide film for cable and ground insulation of the LHC superconducting magnets

    CERN Document Server

    1999-01-01

    This document concerns the award of a contract for the supply of up to 79 tonnes of polyimide film, of three different types, for cable and ground insulation of the LHC superconducting magnets. A call for tenders (IT-2679/LHC/LHC) was sent on 21 September 1999 to two firms in Japan and one firm in the USA. By the closing date, CERN had received three tenders. The Finance Committee is invited to agree to the negotiation of a contract with the firm KANEKA (JP), the lowest bidder, for the supply of 79 tonnes of polyimide film of three different types for an amount of 5 425 541 USD (8 123 284 Swiss francs) for the polyimide film produced in the USA, not subject to revision, and 725 726 546 Japanese yen (10 109 020 Swiss francs) for the polyimide film produced in Japan, not subject to revision, with an option for the supply of up to 20% additional polyimide film of each type, for an amount of 1 085 108 USD (1 624 657 Swiss francs) and 145 145 309 Japanese yen (2 021 804 Swiss francs) respectively, not subject to r...

  9. Toward nonlinear magnonics: Intensity-dependent spin-wave switching in insulating side-coupled magnetic stripes

    Science.gov (United States)

    Sadovnikov, A. V.; Odintsov, S. A.; Beginin, E. N.; Sheshukova, S. E.; Sharaevskii, Yu. P.; Nikitov, S. A.

    2017-10-01

    We demonstrate that the nonlinear spin-wave transport in two laterally parallel magnetic stripes exhibit the intensity-dependent power exchange between the adjacent spin-wave channels. By the means of Brillouin light scattering technique, we investigate collective nonlinear spin-wave dynamics in the presence of magnetodipolar coupling. The nonlinear intensity-dependent effect reveals itself in the spin-wave mode transformation and differential nonlinear spin-wave phase shift in each adjacent magnetic stripe. The proposed analytical theory, based on the coupled Ginzburg-Landau equations, predicts the geometry design involving the reduction of power requirement to the all-magnonic switching. A very good agreement between calculation and experiment was found. In addition, a micromagnetic and finite-element approach has been independently used to study the nonlinear behavior of spin waves in adjacent stripes and the nonlinear transformation of spatial profiles of spin-wave modes. Our results show that the proposed spin-wave coupling mechanism provides the basis for nonlinear magnonic circuits and opens the perspectives for all-magnonic computing architecture.

  10. Effect of magnetic fields on the Kondo insulator CeRhSb: Magnetoresistance and high-field heat capacity measurements

    International Nuclear Information System (INIS)

    Malik, S.K.; Menon, L.; Pecharsky, V.K.; Gschneidner, K.A. Jr.

    1997-01-01

    The compound CeRhSb is a mixed valent Ce-based compound which shows a gap in the electronic density of states at low temperatures. The gap manifests by a rise in electrical resistivity below about 8 K from which the gap energy is estimated to be about 4 K. We have carried out heat capacity measurements on this compound in various applied fields up to 9.85 T. The magnetic contribution to the heat capacity, ΔC, is found to have a maximum in ΔC/T vs T at 10 K, below which ΔC/T is linear with T. This is attributed to the fact that below this temperature, in the gapped state, the electronic density of states decreases linearly with decreasing temperature. On application of a magnetic field, the electronic specific heat coefficient γ in the gapped state increases by ∼4mJ/molK 2 . The maximum in ΔC/T vs T is observed in all fields, which shifts to lower temperatures ∼1K at 5.32 T and raises again at 9.85 T to about the same values as at H=0T. This suggests that the gap exists for all fields up to 9.85 T. Above 10 K, in the mixed-valent state, ΔC/T vs T decreases with increasing temperature in zero field. There is hardly any effect of application of field in the mixed-valent state. We have also carried out magnetoresistance measurements on CeRhSb up to fields of 5.5 T at 2, 4.5, 10, 20, and 30 K. The magnetoresistance in CeRhSb is positive at temperatures of 4.5 K and above, in applied fields up to 5.5 T. At 5.5 T, the magnetoresistance is maximum at 4.5 K (6%) and decreases with increasing temperature. The observation of the maximum is consistent with the observation of a maximum in ΔC/T vs T and is due to a change in the density of states. At a temperature of 2 K, a negative magnetoresistance is observed for magnetic fields greater than ∼3.5T which suggests reduction in the gap. copyright 1997 The American Physical Society

  11. Simulation of the effect of a magnetically insulated anode on a low-power cylindrical Hall thruster

    Science.gov (United States)

    Yongjie, DING; Hong, LI; Boyang, JIA; Peng, LI; Liqiu, WEI; Yu, XU; Wuji, PENG; Hezhi, SUN; Yong, CAO; Daren, YU

    2018-03-01

    The intersection point of the characteristic magnetic field line (CMFL) crossing the anode boundary with the discharge channel wall, and its influence on thruster performance and the energy and flux of ions bombarding the channel wall, have been studied numerically. The simulation results demonstrate that with the increase in distance from the crossover point of the CMFL with the channel wall to the bottom of the thruster channel, the ionization rate in the discharge channel gradually increases; meanwhile, the ion energy and ion current density bombarding the channel wall decreases. When the point of the CMFL with the channel wall is at the channel outlet, the thrust, specific impulse, and efficiency are at a maximum, while the ion energy and ion current density bombarding the channel wall are at a minimum. Therefore, to improve the performance and lifetime of the thruster, it is important to control the point of intersection of the CMFL with the channel wall.

  12. TF34 Quiet Nacelle nearfield acoustic test results

    Science.gov (United States)

    Coward, W. E.; Smith, E. B.; Sowers, H. D.

    1974-01-01

    The results of the nearfield acoustic tests conducted on the TF34 Quiet Nacelle are presented. The high fan noise suppression levels being sought (26 PNdB reduction in aft noise) necessitated the use of an extensive system of special nearfield acoustic instrumentation to properly evaluate the suppression achieved. The design, operation, and test results from each of these nearfield acoustic instrumentation systems are presented.

  13. Correlations in a band insulator

    Czech Academy of Sciences Publication Activity Database

    Sentef, M.; Kuneš, Jan; Werner, P.; Kampf, A. P.

    2009-01-01

    Roč. 80, č. 15 (2009), 155116/1-155116/7 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : electronic correlations * dynamical mean-field theory * band insulator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  14. Magnetically insulated coaxial vacuum diode with partial space-charge-limited explosive emission from edge-type cathode

    Energy Technology Data Exchange (ETDEWEB)

    Belomyttsev, S. Ya.; Rostov, V. V.; Romanchenko, I. V. [Institute of High Current Electronics SB RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); Shunailov, S. A.; Sharypov, K. A.; Shpak, V. G.; Ulmaskulov, M. R. [Institute of Electrophysics UB RAS, 106 Amundsen Str., 620016 Ekaterinburg (Russian Federation); Kolomiets, M. D. [Ural Federal University, 19 Mira Str., 620002 Ekaterinburg (Russian Federation); Mesyats, G. A. [P. N. Lebedev Physical Institute, RAS, 53 Lenin Avenue, 119991 Moscow (Russian Federation); Yalandin, M. I. [Institute of Electrophysics UB RAS, 106 Amundsen Str., 620016 Ekaterinburg (Russian Federation); P. N. Lebedev Physical Institute, RAS, 53 Lenin Avenue, 119991 Moscow (Russian Federation)

    2016-01-14

    The vacuum current associated with any type of electron emission for arbitrary configuration of the diode depends on the combination of the applied electric field and vacuum space charge (VSC) field created by the current. Such fundamental statement should give very close links between the diode current and the normalized cathode field θ which has been introduced by Forbes in 2008 for planar diodes as a reduction in the cathode surface field: θ = field-with/field-without VSC. This article reports the universal approximation of the type of cos(πθ/2) that is the ratio of the actual current and the fully space-charge-limited current. Also, the theoretical treatment and the experimental method of determination of the dynamic emissive characteristics of the macroscopic explosive emission from edge-type cathodes in the coaxial diode are developed. The experimental results obtained with a picosecond time reference between the cathode voltage and the onset of the high-current electron beam exhibit a good coincidence with the theoretical predictions. The presented methods enable the analysis of a real-time-resolved dynamics associated with the dense, magnetized electron beam formation, acceleration and drift motion, including kinematic effects and the phase-stable excitation of high-power microwave oscillators.

  15. BOREAS TF-11 SSA Fen 1996 Water Surface Film Capping Data

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains the TF-11 CO2 chamber flux measurements made with the LI-6200 under water surface film conditions and the TF-11 CO2 chamber concentration measurements made...

  16. Insulating process for HT-7U central solenoid model coils

    International Nuclear Information System (INIS)

    Cui Yimin; Pan Wanjiang; Wu Songtao; Wan Yuanxi

    2003-01-01

    The HT-7U superconducting Tokamak is a whole superconducting magnetically confined fusion device. The insulating system of its central solenoid coils is critical to its properties. In this paper the forming of the insulating system and the vacuum-pressure-impregnating (VPI) are introduced, and the whole insulating process is verified under the super-conducting experiment condition

  17. TFTR D and D Project: Final Examination and Testing of the TFTR TF-Coils

    International Nuclear Information System (INIS)

    Zatz, Irving J.

    2003-01-01

    In operation for nearly 15 years, TFTR (Tokamak Fusion Test Reactor) was not only a fusion science milestone, but a milestone of achievement in engineering as well. The TFTR DandD (Decommissioning and Decontamination) program provided a rare opportunity to examine machine components that had been exposed to a unique performance environment of greater than 100,000 mechanical and thermal load cycles. In particular, the possible examination of the TFTR toroidal-field (TF) coils, which met, then exceeded, the 5.2 Tesla magnetic field machine specification, could supply the answers to many questions that have been asked and debated since the coils were originally designed and built. A test program conducted in parallel with the DandD effort was the chance to look inside and examine, in detail, the TFTR TF coils for the first time since they were delivered encased to PPPL (Princeton Plasma Physics Laboratory). The results from such a program would provide data and insight that would not only be nefit PPPL and the fusion community, but the broader scientific community as well

  18. Results of the TF conductor performance qualification samples for the ITER project

    Science.gov (United States)

    Breschi, M.; Devred, A.; Casali, M.; Bessette, D.; Jewell, M. C.; Mitchell, N.; Pong, I.; Vostner, A.; Bruzzone, P.; Stepanov, B.; Boutboul, T.; Martovetsky, N.; Kim, K.; Takahashi, Y.; Tronza, V.; Yu, Wu

    2012-09-01

    The performance of the toroidal field (TF) magnet conductors for the ITER machine are qualified by a short full-size sample (4 m) current sharing temperature (Tcs) test in the SULTAN facility at CRPP in Villigen, Switzerland, using the operating current of 68 kA and the design peak field of 11.8 T. Several samples, including at least one from each of the six ITER Domestic Agencies participating in TF conductor fabrication (China, European Union, Japan, Russia, South Korea and the United States), have been qualified by the ITER Organization after achieving Tcs values of 6.0-6.9 K, after 700-1000 electromagnetic cycles. These Tcs values exceed the ITER specification and enabled the industrial production of these long-lead items for the ITER tokamak to begin in each Domestic Agency. Some of these samples did not pass the qualification test. In this paper, we summarize the performance of the qualified samples, analyze the effect of strand performance on conductor performance, and discuss the details of the test results.

  19. Unconventional Fermi surface in an insulating state

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Neil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tan, B. S. [Cambridge Univ., Cambridge (United Kingdom); Hsu, Y. -T. [Cambridge Univ., Cambridge (United Kingdom); Zeng, B. [National High Magnetic Field Lab., Tallahassee, FL (United States); Hatnean, M. Ciomaga [Univ. of Warwick, Coventry (United Kingdom); Zhu, Z. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hartstein, M. [Cambridge Univ., Cambridge (United Kingdom); Kiourlappou, M. [Cambridge Univ., Cambridge (United Kingdom); Srivastava, A. [Cambridge Univ., Cambridge (United Kingdom); Johannes, M. D. [Center for Computational Materials Science, Washington, DC (United States); Murphy, T. P. [National High Magnetic Field Lab., Tallahassee, FL (United States); Park, J. -H. [National High Magnetic Field Lab., Tallahassee, FL (United States); Balicas, L. [National High Magnetic Field Lab., Tallahassee, FL (United States); Lonzarich, G. G. [Cambridge Univ., Cambridge (United Kingdom); Balakrishnan, G. [Univ. of Warwick, Coventry (United Kingdom); Sebastian, Suchitra E. [Cambridge Univ., Cambridge (United Kingdom)

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. As a result, the quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior.

  20. Application of calorimetry to the assessment of the performance of ITER Nb3Sn TF conductor samples in SULTAN tests

    International Nuclear Information System (INIS)

    Richard, L Savoldi; Zanino, R

    2008-01-01

    In the frame of the International Thermonuclear Experimental Reactor (ITER), several short full-size Nb 3 Sn samples of candidate toroidal field (TF) conductors were tested in 2007 at the SULTAN facility, PSI Villigen, Switzerland, in conditions relevant to the ITER TF (background magnetic field of 10.78 T and transport current of 68 kA). The performance of a SULTAN sample is determined by the current sharing temperature T CS . This can be obtained in principle from voltage measurements along the conductor sample, but the procedure is not free of issues and ambiguities. Here a complementary approach, based on the calorimetric assessment of the Joule heating due to current sharing, is critically discussed. Suitable algorithms are defined and the respective error bars are estimated, also based on numerical thermal-hydraulic modeling. The calorimetric approach is then applied to assess the performance of the samples tested in 2007 and compared with the results of the standard (electrical) approach

  1. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  2. Dielectric insulation and high-voltage issues

    CERN Document Server

    Tommasini, D

    2010-01-01

    Electrical faults are in most cases dramatic events for magnets, due to the large stored energy which is potentially available to be dissipated at the fault location. After a reminder of the principles of electrostatics in Section 1, the basic mechanisms of conduction and breakdown in dielectrics are summarized in Section 2. Section 3 introduces the types and function of the electrical insulation in magnets, and Section 4 its relevant failure mechanisms. Section 5 deals with ageing and, finally, Section 6 gives some principles for testing. Though the School specifically dealt with warm magnets, for completeness some principles of dielectric insulation for superconducting accelerator magnets are briefly summarized in a dedicated appendix.

  3. Topological insulators fundamentals and perspectives

    CERN Document Server

    Ortmann, Frank; Valenzuela, Sergio O

    2015-01-01

    There are only few discoveries and new technologies in physical sciences that have the potential to dramatically alter and revolutionize our electronic world. Topological insulators are one of them. The present book for the first time provides a full overview and in-depth knowledge about this hot topic in materials science and condensed matter physics. Techniques such as angle-resolved photoemission spectrometry (ARPES), advanced solid-state Nuclear Magnetic Resonance (NMR) or scanning-tunnel microscopy (STM) together with key principles of topological insulators such as spin-locked electronic

  4. A coil test facility for the cryogenic tests of the JT-60SA TF coils

    International Nuclear Information System (INIS)

    Chantant, M.; Genini, L.; Bayetti, P.; Millet, F.; Wanner, M.; Massaut, V.; Corte, A. Della; Ardelier-Desage, F.; Catherine-Dumont, V.; Dael, A.; Decool, P.; Donati, A.; Duchateau, J.L.; Garibaldi, P.; Girard, S.; Hatchressian, J.C.; Fejoz, P.; Jamotton, P.; Jourdheuil, L.; Juster, F.P.

    2011-01-01

    In the framework of the Broader Approach Activities, the EU will deliver to Japan the 18 superconducting coils, which constitute the JT-60SA Toroidal field magnet. These 18 coils, manufactured by France and Italy, will be cold tested before shipping to Japan. For this purpose, the European Joint Undertaking for ITER, the Development of Fusion Energy ('Fusion for Energy', F4E) and the European Voluntary Contributors are collaborating to design and set-up a coil test facility (CTF) and to perform the acceptance test of the 18 JT-60SA Toroidal Field (TF) coils. The test facility is designed to test one coil at a time at nominal current and cryogenic temperature. The test of the first coil of each manufacturer includes a quench triggered by increasing the temperature. The project is presently in the detailed design phase.

  5. Nonequilibrium green function approach to elastic and inelastic spin-charge transport in topological insulator-based heterostructures and magnetic tunnel junctions

    Science.gov (United States)

    Mahfouzi, Farzad

    ferromagnet (FM). I show that this could be due to the existence of Rashba spin-orbit coupling (SOC) at the interface of the FM and insulator. Assuming that the measured signals are quantum mechanical effect where a solution to the time dependent Schrodinger equation is required, I use Keldysh Green function formalism to introduce a "multi-photon" approach which takes into account the effects of time-dependent term exactly up to scatterings from a finite number of photons. We then proceed to find the corresponding Green function numerically using a recursive method which allows us to increase the size of the system significantly. We also implement other approximations such as adiabatic and rotating frame approaches and compared them with our approach. In Chapter 4, I investigate the spin and charge pumping from a precessing magnetization attached to the edge of a 2-dimensional topological insulator (2DTI). We show that, in this system a huge spin current (or voltage signal if the FM covers only one edge) can be pumped for very small cone angles of the precessing FM (proportional to the intensity of the applied microwave). In Chapter 5 I present the third project in this field of research, where, I investigated the pumping from FM attached to a 3-dimensional TI. Spin-transfer torque: Presented in Chapter 6, in this work I investigate the torque induced by a flow of spin-polarized current into a FM and check the condition in which it can cause the magnetization to flip. Motivated by recent experimental developments in the field, here I consider systems with strong SOC such as TIs within a magnetic tunnel junction (MTJ) heterostructure. In the theoretical part I show the correct way (as opposed to the conventional approach used in some theoretical works which suffers from violation of the gauge invariance) to calculate linear-response torque to the external applied voltage and for the numerical calculation I adopted a parallelized adaptive integration algorithm in order to take

  6. Topological insulators and topological superconductors

    CERN Document Server

    Bernevig, Andrei B

    2013-01-01

    This graduate-level textbook is the first pedagogical synthesis of the field of topological insulators and superconductors, one of the most exciting areas of research in condensed matter physics. Presenting the latest developments, while providing all the calculations necessary for a self-contained and complete description of the discipline, it is ideal for graduate students and researchers preparing to work in this area, and it will be an essential reference both within and outside the classroom. The book begins with simple concepts such as Berry phases, Dirac fermions, Hall conductance and its link to topology, and the Hofstadter problem of lattice electrons in a magnetic field. It moves on to explain topological phases of matter such as Chern insulators, two- and three-dimensional topological insulators, and Majorana p-wave wires. Additionally, the book covers zero modes on vortices in topological superconductors, time-reversal topological superconductors, and topological responses/field theory and topolo...

  7. Identifying TF-MiRNA Regulatory Relationships Using Multiple Features.

    Directory of Open Access Journals (Sweden)

    Mingyu Shao

    Full Text Available MicroRNAs are known to play important roles in the transcriptional and post-transcriptional regulation of gene expression. While intensive research has been conducted to identify miRNAs and their target genes in various genomes, there is only limited knowledge about how microRNAs are regulated. In this study, we construct a pipeline that can infer the regulatory relationships between transcription factors and microRNAs from ChIP-Seq data with high confidence. In particular, after identifying candidate peaks from ChIP-Seq data, we formulate the inference as a PU learning (learning from only positive and unlabeled examples problem. Multiple features including the statistical significance of the peaks, the location of the peaks, the transcription factor binding site motifs, and the evolutionary conservation are derived from peaks for training and prediction. To further improve the accuracy of our inference, we also apply a mean reciprocal rank (MRR-based method to the candidate peaks. We apply our pipeline to infer TF-miRNA regulatory relationships in mouse embryonic stem cells. The experimental results show that our approach provides very specific findings of TF-miRNA regulatory relationships.

  8. Topological insulator homojunctions including magnetic layers: the example of n-p type (n-QLs Bi.sub.2./sub.Se.sub.3./sub./Mn-Bi.sub.2./sub.Se.sub.3./sub.) heterostructures

    Czech Academy of Sciences Publication Activity Database

    Vališka, M.; Warmuth, J.; Michiardi, M.; Vondráček, Martin; Ngankeu, A.S.; Holý, V.; Sechovský, V.; Springholz, G.; Bianchi, M.; Wiebe, J.; Hofmann, P.; Honolka, Jan

    2016-01-01

    Roč. 108, č. 26 (2016), 1-4, č. článku 262402. ISSN 0003-6951 R&D Projects: GA MŠk(CZ) LM2011029; GA MŠk LO1409; GA ČR(CZ) GA14-30062S Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 Keywords : topological insulator * Mn-Bi2Se 3 * homojunction * ARPES Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.411, year: 2016

  9. Magnetic, Electrical and Dielectric Properties of LaMnO3+η Perovskite Manganite.

    Science.gov (United States)

    v, Punith Kumar; Dayal, Vijaylakshmi

    The high pure polycrystalline LaMnO3+η perovskite manganite has been synthesized using conventional solid state reaction method. The studied sample crystallizes into orthorhombic O', phase indexed with Pbnm space group. The magnetization measurement exhibits that the studied sample shows paramagnetic (PM) to ferromagnetic (FM) phase transition at TC = 191.6K followed with a frustration due to antiferromagnetic (AFM) kind of spin ordering at low temperature, Tf = 85.8K. The electrical resistivity measurements carried out at 0 tesla and 8 tesla magnetic field exhibits insulating kind of behavior throughout the measured temperature range. The resistivity at 0 tesla exhibits low temperature FM insulator to high temperature PM insulator type phase transition at TC = 191.6K similarly as observed from magnetization measurement. The application of the magnetic field (8 tesla) shifts TC to higher temperature side and the charge transport follows Shklovskii Efros variable range hopping (SE VRH) mechanism. The temperature and frequency dependent dielectric permittivity studied for the sample exhibits relaxation process explained based on Debye +Maxwell-Wagner relaxation mechanism. Department of Atomic Energy-Board of Research in Nuclear Sciences, Government of INDIA.

  10. ITER magnets

    International Nuclear Information System (INIS)

    Bottura, L.; Hasegawa, M.; Heim, J.

    1991-01-01

    As part of the summary of the Conceptual Design Activities (CDA) for the International Thermonuclear Experimental Reactor (ITER), this document describes the magnet systems for ITER, including the Toroidal Field (TF) and Poloidal Field (PF) Magnets, the Structural Support System and Cryostat, the Cryogenic System, the TF and PF Power and Protection Systems, and Coil Services and Diagnostics. After an Introduction and Summary, the document discusses the (i) Design Basis, including General Requirements, Design Criteria, Design Philosophy, and the Database (a.o., engineering data on key materials and components), and (ii) the Subsystem Design and Analysis, including Conductor Design, TF Coil and Structure Design, TF Structural Analysis, PF Coil and Structure Design, PF Structural Performance, Fatigue Assessment of Structures, AC Loss Performance, Thermohydraulic Performance, Stability, Cryogenic System, Power Supply Systems, and Coil Services. All magnets are superconducting, (based on Nb 3 Sn) except the Active Control Coils inside the Vacuum Vessel. The fault analysis has been taken to a level consistent with the design definition, showing that the present design meets the requirement for passive safety or can be made to meet it with only minor modifications. A more detailed assessment in this regard is needed but must await further development of the design. In conclusion, the magnet design concepts presently proposed can be developed into an engineering design. Refs, figs and tabs

  11. Study for Manufacturing of ITER TF Coil Radial Plates

    International Nuclear Information System (INIS)

    Fietz, W.H.; Muetzel, W.

    2006-01-01

    During the previous design phase of ITER the ITER Toroidal Field Model Coil (TFMC) has been built to verify the TF coil concept of ITER and to proof the feasibility of an industrial fabrication of such a coil. In April 2004, Forschungszentrum and BNG, started a Manufacturing Study for the full scale Radial Plates (RP) of the TF Coils in the frame of an EFDA task. The main part of the Study was to develop feasible concepts of the technology for the manufacturing of the Full Scale Radial Plates starting with the raw material until final testing. The Feasibility Study has covered all manufacturing steps that are necessary for production of the RP. It has included as well a basic layout for the manufacturing process. During the work several proposals for the single manufacturing work steps have been developed. After that an evaluation of the found proposals has taken place. The most feasible proposals have been combined to manufacturing concepts. Finally two main Concepts were elaborated and evaluated: Concept 1 includes the premachining of segments with grooves, the welding of the segments and the final machining of the RP. Concept 2 includes the welding of not machined small segments to the D-shape of the RP and the following machining of the surface and grooves. Both Concepts will be described in detail with a comparison of tooling and manufacturing details, achievement of technological requirements as well as with the requirements coming from the overall time schedule. Based on the results of the assessment of the different concepts and manufacturing techniques Concept 1 shows some advantages compared to Concept 2. These will be described in the paper. In addition a proposal about additional R(and)D in front of the later manufacturing will be made. (author)

  12. The emerging role of neutrophils in thrombosis – The journey of TF through NETs

    Directory of Open Access Journals (Sweden)

    Konstantinos eKambas

    2012-12-01

    Full Text Available The production of TF by neutrophils and their contribution in thrombosis was until recently a matter of scientific debate. Experimental data suggested the de novo TF production by neutrophils under inflammatory stimuli, while others proposed that these cells acquired microparticle-derived TF. Recent experimental evidence revealed the critical role of neutrophils in thrombotic events. Neutrophil derived TF has been implicated in this process in several human and animal models. Additionally, neutrophil extracellular trap (NET release has emerged as a major contributor in neutrophil-driven thrombogenicity in disease models including sepsis, deep venous thrombosis and malignancy. It is suggested that NETs provide the scaffold for fibrin deposition and platelet entrapment and subsequent activation. The recently reported autophagy-dependent extracellular delivery of TF in NETs further supports the involvement of neutrophils in thrombosis. Herein, we seek to review novel data regarding the role of neutrophils in thrombosis, emphasizing the implication of TF and NETs.

  13. Wormhole effect in a strong topological insulator

    Science.gov (United States)

    Rosenberg, G.; Guo, H.-M.; Franz, M.

    2010-07-01

    An infinitely thin solenoid carrying magnetic flux Φ (a “Dirac string”) inserted into an ordinary band insulator has no significant effect on the spectrum of electrons. In a strong topological insulator, remarkably, such a solenoid carries protected gapless one-dimensional fermionic modes when Φ=hc/2e . These modes are spin-filtered and represent a distinct bulk manifestation of the topologically nontrivial insulator. We establish this “wormhole” effect by both general qualitative considerations and by numerical calculations within a minimal lattice model. We also discuss the possibility of experimental observation of a closely related effect in artificially engineered nanostructures.

  14. Magnetic properties of bi-, tri- and multicrystals of 3D topological insulator Bi{sub 1−x}–Sb{sub x}(0.06⩽x⩽0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Muntyanu, F.M. [Institute of Electronic Engineering and Industrial Technologies, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of); International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Gilewski, A., E-mail: andrzej.gilewski@ml.pan.wroc.pl [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Nenkov, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Leibniz-Institut fur Festkorper und Werkstofforschung, Dresden 01171 (Germany); Rogacki, K. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Institute of Low Temperatures and Structural Research, Polish Academy of Sciences, Wroclaw 50950 (Poland); Zaleski, A.J. [Institute of Low Temperatures and Structural Research, Polish Academy of Sciences, Wroclaw 50950 (Poland); Fuks, G. [International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw 53421 (Poland); Leibniz-Institut fur Festkorper und Werkstofforschung, Dresden 01171 (Germany); Chistol, V. [Technical University of Moldova, Chisinau 2004 (Moldova, Republic of)

    2014-03-01

    The magnetic properties of bi-, tri- and multicrystals of 3D topological insulator Bi{sub 1−x}Sb{sub x}(0.06magnetic field expulsion have been observed simultaneously.

  15. Magnetic and electrical response of Co-doped La{sub 0.7}Ca{sub 0.3}MnO{sub 3} manganites/insulator system

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, J.C., E-mail: Jyotish.debnath@deakin.edu.au [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia); Wang, Jianli, E-mail: jcd341@uowmail.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2017-01-01

    We present a systematic study of the structural, magnetic and electrical properties of La{sub 0.7}Ca{sub 0.3}MnO{sub 3} (LCMO) and La{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}Co{sub 0.05}O{sub 3} (LCMCO0 perovskite manganites. Most of the work is devoted to the electrical properties with a thorough discussion about different models for both the metallic and insulator states. With a view to understand the conduction mechanism in these materials, the resistivity of both materials was measured over a temperature range 5–300 K and in a magnetic field up to 1 T and the data were analysed by using several theoretical models. It has been observed that the metallic part of the temperature dependent resistivity (ρ) curve fits well with ρ=ρ{sub 0} +ρ{sub 2,5}Τ{sup 2,5}, indicating the electron–magnon scattering processes in the conduction of these materials. On the other hand, in the high temperature paramagnetic insulating regime, the adiabatic small polaron and VRH models fit well, thereby indicating that polaron hopping might be responsible for the conduction mechanism.

  16. Transport Experiments on Topological Insulators

    Science.gov (United States)

    2016-08-16

    neutral currents as well. In insulating magnets, the heat current below 2 K is largely carried by spin waves or magnons (phonons die out rapidly below 2 K...are not magnons (theorists call them “spinons”). The 2 experiments confirm that \\Omega can exert a large Hall-like force on excitations even when...largely carried by spin waves or magnons (phonons die out rapidly below 2 K). In a certain class of magnets with a Kagome lattice, theory predicts that

  17. Qualification tests for ITER TF conductors in SULTAN

    International Nuclear Information System (INIS)

    Bruzzone, P.; Stepanov, B.; Wesche, R.

    2009-01-01

    From February 2007 to May 2008, 18 short length conductor sections have been tested in SULTAN for design verification and manufacturer qualification of the ITER Toroidal Field (TF) conductor. The test program is focussed on the current sharing temperature, T cs , at the nominal operating conditions, 68 kA current and 11.15 T effective field, which can be fully reproduced in the SULTAN test facility. A broad range of results was observed, with over 2 K difference among the T cs of the conductors. In average, the results are poorer compared to the potential performance estimated from the strand scaling law. The key parameters to mitigate the degradation are not yet clearly identified. The experimental challenges to test conductors with performance degradation are highlighted, including enhanced instrumentation sets, the application of gas flow calorimetry to sense the current sharing power and the post-processing of voltage data to cancel the transverse potential across the cable. The updated schedule of the tests in SULTAN is presented with the short-term action plan for conductor test.

  18. Magnonic topological insulators in antiferromagnets

    Science.gov (United States)

    Nakata, Kouki; Kim, Se Kwon; Klinovaja, Jelena; Loss, Daniel

    2017-12-01

    Extending the notion of symmetry protected topological phases to insulating antiferromagnets (AFs) described in terms of opposite magnetic dipole moments associated with the magnetic N e ´el order, we establish a bosonic counterpart of topological insulators in semiconductors. Making use of the Aharonov-Casher effect, induced by electric field gradients, we propose a magnonic analog of the quantum spin Hall effect (magnonic QSHE) for edge states that carry helical magnons. We show that such up and down magnons form the same Landau levels and perform cyclotron motion with the same frequency but propagate in opposite direction. The insulating AF becomes characterized by a topological Z2 number consisting of the Chern integer associated with each helical magnon edge state. Focusing on the topological Hall phase for magnons, we study bulk magnon effects such as magnonic spin, thermal, Nernst, and Ettinghausen effects, as well as the thermomagnetic properties of helical magnon transport both in topologically trivial and nontrivial bulk AFs and establish the magnonic Wiedemann-Franz law. We show that our predictions are within experimental reach with current device and measurement techniques.

  19. Special remote tooling developed and utilized to tighten TFTR TF coil casing bolts

    International Nuclear Information System (INIS)

    Burgess, T.W.; Walton, G.R.; Meighan, T.G.; Paul, B.L.

    1993-01-01

    Special tooling has been developed and used to tighten toroidal field (TF) coil casing bolts that have loosened from years of Tokamak Fusion Test Reactor (TFTR) operation. Due to their location, many of the TF casing bolts cannot be directly accessed or viewed; their condition was first discovered during unrelated inspections in 1988. Engineering solutions were, sought until 1992, when a remotely operated wrench concept was successfully demonstrated on a TF coil mockup. The concept was developed into several working tools that have successfully been applied to tighten several thousand TF casing bolts during recent scheduled outages. This effort has improved the integrity and reliability of the TF coil system in preparing for the final experimental phase of the TFTR. This paper discusses the design and application of this tooling

  20. Improvements, enhancements, and optimizations of COBRA-TF

    International Nuclear Information System (INIS)

    Salko, R. K.; Avramova, M. N.; Hooper, R.; Palmtag, S.; Popov, E.; Turner, J.

    2013-01-01

    The Reactor Dynamics and Fuel Management Group (RDFMG) at The Pennsylvania State University (PSU) has become active in the Consortium for Advanced Simulation of Light Water Reactors (CASL) program by delivering, supporting, and further developing CTF, the PSU version of the Coolant Boiling in Rod Arrays - Two Fluids (COBRA-TF) Thermal/Hydraulic (T/H), sub-channel program. New development work on CTF was primarily geared towards decreasing the execution time of the code so that it may eventually be used for performing pin-by-pin, full-core simulations. Great gains have been made through targeting sections of source code for optimization. For example, wall clock time has been reduced for a one-assembly, three-dimensional model, containing ∼9,400 mesh cells, from 9.2 min to 1 min. A further improvement has been reduction in code memory usage, which was previously prohibitive for large models. In conjunction with the run time speedups, this has enabled the simulation of a refined quarter-core model (∼460,000 mesh cells), which saw a reduction in memory usage from over 130 GB to less than 3 GB. In addition to the optimization work, RDFMG has also created a preprocessor utility for the fast and less error-prone generation of CTF input decks. Furthermore, basic post-processing capabilities have been implemented by creating a CTF subroutine for producing Visualization Tool-Kit (VTK) files that output mesh data and associated simulation results. These VTK files can be opened with visualization software. (authors)

  1. FVIIa-sTF and Thrombin Inhibitory Activities of Compounds Isolated from Microcystis aeruginosa K-139.

    Science.gov (United States)

    Anas, Andrea Roxanne J; Mori, Akane; Tone, Mineka; Naruse, Chiaki; Nakajima, Anna; Asukabe, Hirohiko; Takaya, Yoshiaki; Imanishi, Susumu Y; Nishizawa, Tomoyasu; Shirai, Makoto; Harada, Ken-Ichi

    2017-08-30

    The rise of bleeding and bleeding complications caused by oral anticoagulant use are serious problems nowadays. Strategies that block the initiation step in blood coagulation involving activated factor VII-tissue factor (fVIIa-TF) have been considered. This study explores toxic Microcystis aeruginosa K-139, from Lake Kasumigaura, Ibaraki, Japan, as a promising cyanobacterium for isolation of fVIIa-sTF inhibitors. M. aeruginosa K-139 underwent reversed-phase solid-phase extraction (ODS-SPE) from 20% MeOH to MeOH elution with 40%-MeOH increments, which afforded aeruginosin K-139 in the 60% MeOH fraction; micropeptin K-139 and microviridin B in the MeOH fraction. Aeruginosin K-139 displayed an fVIIa-sTF inhibitory activity of ~166 µM, within a 95% confidence interval. Micropeptin K-139 inhibited fVIIa-sTF with EC 50 10.62 µM, which was more efficient than thrombin inhibition of EC 50 26.94 µM. The thrombin/fVIIa-sTF ratio of 2.54 in micropeptin K-139 is higher than those in 4-amidinophenylmethane sulfonyl fluoride (APMSF) and leupeptin, when used as positive controls. This study proves that M. aeruginosa K-139 is a new source of fVIIa-sTF inhibitors. It also opens a new avenue for micropeptin K-139 and related depsipeptides as fVIIa-sTF inhibitors.

  2. FVIIa-sTF and Thrombin Inhibitory Activities of Compounds Isolated from Microcystis aeruginosa K-139

    Directory of Open Access Journals (Sweden)

    Andrea Roxanne J. Anas

    2017-08-01

    Full Text Available The rise of bleeding and bleeding complications caused by oral anticoagulant use are serious problems nowadays. Strategies that block the initiation step in blood coagulation involving activated factor VII-tissue factor (fVIIa-TF have been considered. This study explores toxic Microcystis aeruginosa K-139, from Lake Kasumigaura, Ibaraki, Japan, as a promising cyanobacterium for isolation of fVIIa-sTF inhibitors. M. aeruginosa K-139 underwent reversed-phase solid-phase extraction (ODS-SPE from 20% MeOH to MeOH elution with 40%-MeOH increments, which afforded aeruginosin K-139 in the 60% MeOH fraction; micropeptin K-139 and microviridin B in the MeOH fraction. Aeruginosin K-139 displayed an fVIIa-sTF inhibitory activity of ~166 µM, within a 95% confidence interval. Micropeptin K-139 inhibited fVIIa-sTF with EC50 10.62 µM, which was more efficient than thrombin inhibition of EC50 26.94 µM. The thrombin/fVIIa-sTF ratio of 2.54 in micropeptin K-139 is higher than those in 4-amidinophenylmethane sulfonyl fluoride (APMSF and leupeptin, when used as positive controls. This study proves that M. aeruginosa K-139 is a new source of fVIIa-sTF inhibitors. It also opens a new avenue for micropeptin K-139 and related depsipeptides as fVIIa-sTF inhibitors.

  3. Pressure effect on magnetic and insulator-metal transition of La.sub.0.67./sub.Pb.sub.0.33./sub.Mn.sub.0.9./sub.Co.sub.0.1./sub.O.sub.2.97./sub. ceramic

    Czech Academy of Sciences Publication Activity Database

    Mihalik, M.; Zentková, M.; Antoňák, M.; Arnold, Zdeněk; Kamarád, Jiří; Skorokhod, Yuriy; Gritzner, G.; Kiss, L. F.

    2012-01-01

    Roč. 32, č. 1 (2012), s. 145-149 ISSN 0895-7959. [Conference of the European High Pressure Research Group (EHPRG) /49./. Budapest, 28.08.2011-02.09.2011] Grant - others:VEGA(SK) 2/0057/27 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic transition: insulator-metal transition * hydrostatic pressure * manganite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.901, year: 2012 www.tandfonline.com

  4. Inflammatory Macrophage Phenotype in BTBR T+tf/J Mice

    Directory of Open Access Journals (Sweden)

    Paul eAshwood

    2013-09-01

    Full Text Available Although autism is a behaviorally defined disorder, many studies report an association with increased pro-inflammatory cytokine production. Recent characterization of the BTBR T+tf/J (BTBR inbred mouse strain has revealed several behavioral characteristics including social deficits, repetitive behavior, and atypical vocalizations which may be relevant to autism. We therefore hypothesized that asocial BTBR mice, which exhibit autism-like behaviors, may have an inflammatory immune profile similar to that observed in children with autism. The objectives of this study were to characterize the myeloid immune profile of BTBR mice and to explore their associations with autism-relevant behaviors. C57BL/6J (C57 mice and BTBR mice were tested for social interest and repetitive self-grooming behavior. Cytokine production was measured in bone-marrow derived macrophages incubated for 24 hours in either growth media alone, LPS, IL-4/ LPS, or IFNγ/ LPS to ascertain any M1/M2 skewing. After LPS stimulation, BTBR macrophages produced higher levels of IL-6, MCP-1, and MIP-1α and lower IL-10 (p<0.01 that C57 mice, suggesting an exaggerated inflammatory profile. After exposure to IL-4/LPS BTBR macrophages produced less IL-10 than C57 macrophages and more IL-12p40 (p<0.01 suggesting poor M2 polarization. Levels of IL-12(p70 (p<0.05 were higher in BTBR macrophages after IFNγ/LPS stimulation, suggesting enhanced M1 polarization. We further observed a positive correlation between grooming frequency, and production of IL-12(p40, IL-12p70, IL-6, and TNFα (p<0.05 after treatment with IFNγ/LPS across both strains. Collectively, these data suggest that the asocial BTBR mouse strain exhibits a more inflammatory, or M1, macrophage profile in comparison to social C57 strain. We have further demonstrated a relationship between this relative increase in inflammation and repetitive grooming behavior, which may have relevance to repetitive and stereotyped behavior of autism.

  5. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  6. Exploring Homeowners’ Insulation Activity

    OpenAIRE

    Friege, J; Holtz, G; Chappin, E.J.L.

    2016-01-01

    Insulating existing buildings offers great potential for reducing greenhouse gas emissions and meeting Germany’s climate protection targets. Previous research suggests that, since homeowners’ decision-making processes are inadequately understood as yet, today’s incentives aiming at increasing insulation activity lead to unsatisfactory results. We developed an agent-based model to foster the understanding of homeowners’ decision-making processes regarding insulation and to explore how situatio...

  7. Fluorescent particles in the antibody solution result in false TF- and CD14-positive microparticles in flow cytometric analysis.

    Science.gov (United States)

    Aass, Hans Christian D; Øvstebø, Reidun; Trøseid, Anne-Marie S; Kierulf, Peter; Berg, Jens Petter; Henriksson, Carola Elisabeth

    2011-12-01

    Tissue factor (TF)-positive microparticles (MPs) are highly procoagulant, and linked to thrombosis in sepsis and cancer. MP-associated TF may be assayed by immunological or functional methods. Several reports have demonstrated discrepancies between TF-protein and TF-activity, which have been explained by antibody binding to "encrypted" or degraded forms of inactive TF-protein. Our goal was to evaluate the possible interference of fluorescent antibody aggregates in solutions containing antibodies against TF and CD14 in flow cytometric analysis. Using monocyte-derived microparticles (MPs) released from human monocytes, incubated with or without lipopolysaccharides (LPS) in vitro, we measured MP-associated TF-protein (flow cytometry) and TF-activity (clot formation assay). MPs released from monocytes exposed to LPS (1 ng mL(-1) ) had ∼14 times higher TF-activity than MPs originated from monocytes exposed to only culture medium. However, using untreated anti-TF antibodies (American Diagnostica and BD) in the flow cytometric analysis, MPs released from unstimulated monocytes had a similar number of TF-positive events as MPs secernated from LPS-stimulated monocytes [∼45,000 events mL(-1) (American Diagnostica); ∼15,000 events mL(-1) (BD)]. These TF-positive events did not exert any TF-activity, and centrifugation (17,000g, 30 min, 4°C) of the antibody solutions prior to use effectively removed the interfering fluorescent events. Removal of fluorescent interference, probably in the form of fluorescent antibody aggregates, from the antibody solutions by centrifugation is essential to prevent the occurrence of false positive flow cytometric events. The events can be mistaken as MP-associated TF-protein, and interpreted as a discrepancy between TF-protein and TF-activity. Copyright © 2011 International Society for Advancement of Cytometry.

  8. Imaging Dirac-mass disorder from magnetic dopant atoms in the ferromagnetic topological insulator Crx(Bi0.1Sb0.9)2-xTe3.

    Science.gov (United States)

    Lee, Inhee; Kim, Chung Koo; Lee, Jinho; Billinge, Simon J L; Zhong, Ruidan; Schneeloch, John A; Liu, Tiansheng; Valla, Tonica; Tranquada, John M; Gu, Genda; Davis, J C Séamus

    2015-02-03

    To achieve and use the most exotic electronic phenomena predicted for the surface states of 3D topological insulators (TIs), it is necessary to open a "Dirac-mass gap" in their spectrum by breaking time-reversal symmetry. Use of magnetic dopant atoms to generate a ferromagnetic state is the most widely applied approach. However, it is unknown how the spatial arrangements of the magnetic dopant atoms influence the Dirac-mass gap at the atomic scale or, conversely, whether the ferromagnetic interactions between dopant atoms are influenced by the topological surface states. Here we image the locations of the magnetic (Cr) dopant atoms in the ferromagnetic TI Cr0.08(Bi0.1Sb0.9)1.92Te3. Simultaneous visualization of the Dirac-mass gap Δ(r) reveals its intense disorder, which we demonstrate is directly related to fluctuations in n(r), the Cr atom areal density in the termination layer. We find the relationship of surface-state Fermi wavevectors to the anisotropic structure of Δ(r) not inconsistent with predictions for surface ferromagnetism mediated by those states. Moreover, despite the intense Dirac-mass disorder, the anticipated relationship [Formula: see text] is confirmed throughout and exhibits an electron-dopant interaction energy J* = 145 meV·nm(2). These observations reveal how magnetic dopant atoms actually generate the TI mass gap locally and that, to achieve the novel physics expected of time-reversal symmetry breaking TI materials, control of the resulting Dirac-mass gap disorder will be essential.

  9. Inducing magneto-electric response in topological insulator

    International Nuclear Information System (INIS)

    Zeng, Lunwu; Song, Runxia; Zeng, Jing

    2013-01-01

    Utilizing electric potential and magnetic scalar potential formulas, which contain zero-order Bessel functions of the first kind and the constitutive relations of topological insulators, we obtained the induced magnetic scalar potentials and induced magnetic monopole charges which are induced by a point charge in topological insulators. The results show that infinite image magnetic monopole charges are generated by a point electric charge. The magnitude of the induced magnetic monopole charges are determined not only by the point electric charge, but also by the material parameters. - Highlights: ► Electric potential and magnetic scalar potential which contain zero-order Bessel function of the first kind were derived. ► Boundary conditions of topological insulator were built. ► Induced monopole charges were worked out.

  10. Tf2NH-Catalyzed Amide Synthesis from Vinyl Azides and Alcohols.

    Science.gov (United States)

    Zhang, Feng-Lian; Zhu, Xu; Chiba, Shunsuke

    2015-06-19

    Triflimide (Tf2NH) specifically catalyzed reactions of alcohols and vinyl azides, enabling efficient construction of amides with C-C bond formation through nucleophilic attack of vinyl azides onto the putative carbocation intermediates derived from alcohols are described.

  11. 78 FR 39057 - Environmental Impact Statement: T.F. Green Airport, Warwick, Rhode Island

    Science.gov (United States)

    2013-06-28

    ... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Environmental Impact Statement: T.F. Green Airport, Warwick, Rhode Island AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice..., Environmental Program Manager, Federal Aviation Administration New England, 12 New England Executive Park...

  12. Data of evolutionary structure change: 1YDVA-2V0TF [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1YDVA-2V0TF 1YDV 2V0T A F --RKYFVAANWKCNGTLESIKSLTNSFNNLDFDPSKLDV...SGAFTGEVSLPILKDFGVNWIVLGHSERRAYYGETNEIVADKVAAAVASGFMVIACIGETLQERESGRTAVVVLTQIAAIAKKLKKADWAKVVIAYEPVW-------LTPQQAQEAHALIRSWVSSKIGADVA...ID> 0 1YDV A 1YDVAA 1YDVA VDLID--NFDNV 1YDV A 1YDVA

  13. HARD: SUBJECT-BASED SEARCH ENGINE MENGGUNAKAN TF-IDF DAN JACCARD'S COEFFICIENT

    Directory of Open Access Journals (Sweden)

    Rolly Intan

    2006-01-01

    Full Text Available This paper proposes a hybridized concept of search engine based on subject parameter of High Accuracy Retrieval from Documents (HARD. Tf-Idf and Jaccard's Coefficient are modified and extended to providing the concept. Several illustrative examples are given including their steps of calculations in order to clearly understand the proposed concept and formulas. Abstract in Bahasa Indonesia : Paper ini memperkenalkan suatu algorima search engine berdasarkan konsep HARD (High Accuracy Retrieval from Documents dengan menggabungkan penggunaan metoda TF-IDF (Term Frequency Inverse Document Frequency dan Jaccard's Coefficient. Kedua metoda, TF-IDF dan Jaccard's Coefficient dimodifikasi dan dikembangkan dengan memperkenalkan beberapa rumusan baru. Untuk lebih memudahkan dalam mengerti algoritma dan rumusan baru yang diperkenalkan, beberapa contoh perhitungan diberikan. Kata kunci: HARD, Tf-Idf, koefisien Jaccard, search engine, himpunan fuzzy.

  14. BOREAS TF-10 NSA-YJP Tower Flux, Meteorological, and Porometry Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The flux and ancillary data collected at the NSA-YJP tower flux site by the TF-10 group. Measurements of stomatal conductance collected at the NSA-YJP site by the...

  15. Effect of Biozyme T.F. on yield and quality of tomato ( Lycopersicon ...

    African Journals Online (AJOL)

    entreprise pour déterminer l'effet de Biozyme T.F., un engrais foliaire, sur la croissance et le rendement de tomate. Les plantes étaient traitées avec Biozyme T.F. de concentrations de 250, 500 et 700 cc ha-1. Les plantes traitées de Biozyme augmentaient le pourcentage de nouaison de fruit, nombre moyen de fruit/plante, ...

  16. Modulation of COUP-TF expression in a cnidarian by ectopic Wnt signalling and allorecognition.

    Directory of Open Access Journals (Sweden)

    David J Duffy

    2011-04-01

    Full Text Available COUP transcription factors are required for the regulation of gene expression underlying development, differentiation, and homeostasis. They have an evolutionarily conserved function, being a known marker for neurogenesis from cnidarians to vertebrates. A homologue of this gene was shown previously to be a neuronal and nematocyte differentiation marker in Hydra. However, COUP-TFs had not previously been studied in a colonial cnidarian.We cloned a COUP-TF homologue from the colonial marine cnidarian Hydractinia echinata. Expression of the gene was analysed during normal development, allorecognition events and ectopic Wnt activation, using in situ hybridisation and quantitative PCR. During normal Hydractinia development, the gene was first expressed in post-gastrula stages. It was undetectable in larvae, and its mRNA was present again in putative differentiating neurons and nematocytes in post-metamorphic stages. Global activation of canonical Wnt signalling in adult animals resulted in the upregulation of COUP-TF. We also monitored a strong COUP-TF upregulation in stolons undergoing allogeneic interactions. COUP-TF mRNA was most concentrated in the tissues that contacted allogeneic, non-self tissues, and decreased in a gradient away from the contact area. Interestingly, the gene was transiently upregulated during initial contact of self stolons, but dissipated rapidly following self recognition, while in non-self contacts high expression levels were maintained.We conclude that COUP-TF is likely involved in neuronal/nematocyte differentiation in a variety of contexts. This has now been shown to include allorecognition, where COUP-TF is thought to have been co-opted to mediate allorejection by recruiting stinging cells that are the effectors of cytotoxic rejection of allogeneic tissue. Our findings that Wnt activation upregulates COUP-TF expression suggests that Wnts' role in neuronal differentiation could be mediated through COUP-TF.

  17. Problems in modeling TF ripple loss of fast alphas from a tokamak reactor

    Energy Technology Data Exchange (ETDEWEB)

    Hively, L.M.

    1987-01-01

    The present status of modeling TF ripple loss of fast alphas from tokamaks is summarized. The modeling issues are discussed, and several new aspects of this problem are described, including gyromotion, radial electric field, and sawtoothing. Existing models predict that TF ripple loss of fast alphas will have a low-to-moderate impact on the design of a tokamak engineering test reactor (ETR). 52 refs., 3 figs., 2 tabs.

  18. Genomic analysis of Pseudomonas putida phage tf with localized single-strand DNA interruptions.

    Directory of Open Access Journals (Sweden)

    Anatoly S Glukhov

    Full Text Available The complete sequence of the 46,267 bp genome of the lytic bacteriophage tf specific to Pseudomonas putida PpG1 has been determined. The phage genome has two sets of convergently transcribed genes and 186 bp long direct terminal repeats. The overall genomic architecture of the tf phage is similar to that of the previously described Pseudomonas aeruginosa phages PaP3, LUZ24 and phiMR299-2, and 39 out of the 72 products of predicted tf open reading frames have orthologs in these phages. Accordingly, tf was classified as belonging to the LUZ24-like bacteriophage group. However, taking into account very low homology levels between tf DNA and that of the other phages, tf should be considered as an evolutionary divergent member of the group. Two distinguishing features not reported for other members of the group were found in the tf genome. Firstly, a unique end structure--a blunt right end and a 4-nucleotide 3'-protruding left end--was observed. Secondly, 14 single-chain interruptions (nicks were found in the top strand of the tf DNA. All nicks were mapped within a consensus sequence 5'-TACT/RTGMC-3'. Two nicks were analyzed in detail and were shown to be present in more than 90% of the phage population. Although localized nicks were previously found only in the DNA of T5-like and phiKMV-like phages, it seems increasingly likely that this enigmatic structural feature is common to various other bacteriophages.

  19. The orbital magnetization of a Mott insulator, V{sub 2}O{sub 3} revealed by resonant x-ray Bragg diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Lovesey, S.; Knight, K.; Sivia, D

    2001-03-01

    Structure factors calculated for x-ray Bragg diffraction by magnetically ordered vanadium sesquioxide, V{sub 2}O{sub 3}, with signal enhancement from the vanadium K-shell resonance, are compared with data gathered in azimuthal-angle scans at space-group forbidden reflections. Diffraction enhanced by a K-shell resonance reveals properties of the orbital magnetization in the valence shell of the resonant ion whereas other core states, which have two partners because of the spin-orbit interaction, reveal properties of both the spin and orbital magnetization in the valence shell. Agreement on all issues between observed and calculated Bragg intensities support the use of an atomic model for the interpretation of data. The reflections are shown to be purely magnetic, and associated with the orbital magnetic moment and the octupole moment of a vanadium ion. Reflections with the Miller index h even are analysed to give the canting angle of the magnetic easy-axis. Data from the rotated ({pi}'{sigma}) and unrotated ({sigma}'{sigma}) channels of scattering provide an angle consistent with an earlier interpretation of magnetic neutron diffraction. With h odd diffraction enhanced by an E1 event is forbidden. Intensities enhanced by an E2 event are from anisotropic components of the octupole moment, and the dominant contribution has three-fold rotational symmetry which is an imprint of the high-temperature trigonal structure. Analysis of azimuthal-angle scans, with h even and h odd, provides estimates of orbital moments that in the future can be confronted with ab initio calculations of the electronic properties of V{sub 2}O{sub 3}. By and large, the complicated pattern of azimuthal-angle scans can be attributed to the low symmetry (monoclinic) structure adopted below the Neel temperatures. (author)

  20. Fault condition stress analysis of NET 16 TF coil model

    International Nuclear Information System (INIS)

    Jong, C.T.J.

    1992-04-01

    As part of the design process of the NET/ITER toroidal field coils (TFCs), the mechanical behaviour of the magnetic system under fault conditions has to be analysed in some detail. Under fault conditions, either electrical or mechanical, the magnetic loading of the coils becomes extreme and further mechanical failure of parts of the overall structure might occur (e.g. failure of the coil, gravitational support, intercoil structure). The mechanical behaviour of the magnetic system under fault conditions has been analysed with a finite element model of the complete TFC system. The analysed fault conditions consist of: a thermal fault, electrical faults and mechanical faults. The mechanical faults have been applied simultaneously with an electrical fault. This report described the work carried out to create the finite element model of 16 TFCs and contains an extensive presentation of the results, obtained with this model, of a normal operating condition analysis and 9 fault condition analyses. Chapter 2-5 contains a detailed description of the finite element model, boundary conditions and loading conditions of the analyses made. Chapters 2-4 can be skipped if the reader is only interested in results. To understand the results presented chapter 6 is recommended, which contains a detailed description of all analysed fault conditions. The dimensions and geometry of the model correspond to the status of the NET/ITER TFC design of May 1990. Compared with previous models of the complete magnetic system, the finite element model of 16 TFCs is 'detailed', and can be used for linear elastic analysis with faulted loads. (author). 8 refs.; 204 figs.; 134 tabs

  1. TfAP-2 is required for night sleep in Drosophila.

    Science.gov (United States)

    Kucherenko, Mariya M; Ilangovan, Vinodh; Herzig, Bettina; Shcherbata, Halyna R; Bringmann, Henrik

    2016-11-09

    The AP-2 transcription factor APTF-1 is crucially required for developmentally controlled sleep behavior in Caenorhabditis elegans larvae. Its human ortholog, TFAP-2beta, causes Char disease and has also been linked to sleep disorders. These data suggest that AP-2 transcription factors may be highly conserved regulators of various types of sleep behavior. Here, we tested the idea that AP-2 controls adult sleep in Drosophila. Drosophila has one AP-2 ortholog called TfAP-2, which is essential for viability. To investigate its potential role in sleep behavior and neural development, we specifically downregulated TfAP-2 in the nervous system. We found that neuronal TfAP-2 knockdown almost completely abolished night sleep but did not affect day sleep. TfAP-2 insufficiency affected nervous system development. Conditional TfAP-2 knockdown in the adult also produced a modest sleep phenotype, suggesting that TfAP-2 acts both in larval as well as in differentiated neurons. Thus, our results show that AP-2 transcription factors are highly conserved regulators of development and sleep.

  2. Thermal insulation blanket material

    Science.gov (United States)

    Pusch, R. H.

    1982-01-01

    A study was conducted to provide a tailorable advanced blanket insulation based on a woven design having an integrally woven core structure. A highly pure quartz yarn was selected for weaving and the cells formed were filled with a microquartz felt insulation.

  3. Translucent insulating building envelope

    DEFF Research Database (Denmark)

    Rahbek, Jens Eg

    1997-01-01

    A new type of translucent insulating material has been tested. This material is made of Celulose-Acetat and have a honey-comb structure. The material has a high solar transmittance and is highly insulating. The material is relatively cheap to produce. Danish Title: Translucent isolerende klimaskærm....

  4. Sound Insulation between Dwellings

    DEFF Research Database (Denmark)

    Rasmussen, Birgit

    2011-01-01

    Regulatory sound insulation requirements for dwellings exist in more than 30 countries in Europe. In some countries, requirements have existed since the 1950s. Findings from comparative studies show that sound insulation descriptors and requirements represent a high degree of diversity...... and initiate – where needed – improvement of sound insulation of new and existing dwellings in Europe to the benefit of the inhabitants and the society. A European COST Action TU0901 "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", has been established and runs...... 2009-2013. The main objectives of TU0901 are to prepare proposals for harmonized sound insulation descriptors and for a European sound classification scheme with a number of quality classes for dwellings. Findings from the studies provide input for the discussions in COST TU0901. Data collected from 24...

  5. Development of high-mechanical strength electrical insulations for tokamak toroidal field coils

    International Nuclear Information System (INIS)

    Burke, C.

    1977-01-01

    The electrical insulation for the TF (Toroidal Field) coils is subjected to a high interlaminar shear, tensile and compressive stresses. Two candidate epoxy/glass fiber systems using prepreg and vacuum impregnation techniques were evaluated. Specimens were prepared and processed under controlled conditions to simulate specification manufacturing procedures. The strengths of the insulation were measured in interlaminar shear, tension, compression, and combined shear and compression statically. Shear modulus determinations were also made. Various techniques of surface treatments to increase bond strengths with three resin primers were tested

  6. Fabrication and Test of a Nb3Sn Model Magnet With Ceramic Insulation for the Next Generation Undulator of the LHC

    CERN Document Server

    Elias, N; Dalexandro, N; Giloux, C; Bordini, B; Maccaferri, R

    2010-01-01

    The future run of the Large Hadron Collider with lead ions will require important modifications in the synchrotron radiation profile monitor system, which at present comprises two superconducting undulators wound from Nb-Ti conductor, delivering 5 T in a 60 mm gap, and with a period of 280 mm. Whilst the gap and the nominal field of the future undulators will remain the same, the period shall be 140 mm, which translates to a peak field of over 8 T in the coils and hence requires the use of Nb3Sn technology. In this paper the electromagnetic design of the undulator is summarized. We describe the fabrication of a race-track coil wound with a 0.8 mm diameter Nb3Sn strand with ceramic insulation. Finally, the results of successful tests made at 4.3 K and 1.9 K in a mirror configuration are presented. 10 T at 4.3 K and 11.5 T at 1.9 K were measured in the yoke gap, thus validating this concept for the future undulator.

  7. Helium Nanodroplet Isolation of Ionic Liquid Vapor: Inrared Laser Spectroscopy of [EMIM][Tf_2N

    Science.gov (United States)

    Flynn, Steven D.; Douberly, Gary E.

    2012-06-01

    The Infrared spectrum of the vapor produced upon thermal vaporization of the [emim][Tf_2N] ionic liquid has been obtained using the helium nanodroplet isolation method. Despite the low vapor pressure of [emim][Tf_2N], sufficient gas phase densities are produced, allowing for efficient helium nanodroplet pick-up. The mass spectrum of the emim[Tf_2N] doped droplet beam shows signatures that have been attributed in gas phase measurements to the presence of isolated, intact [emim][Tf_2N] ion-pairs. Furthermore, the mass spectrometry results indicate that emim[Tf_2N] does not undergo thermal decomposition at 410 K. Comparisons are made between the experimental measurements and ab initio calculations (mp2/6-311++g(d,p)) of the CH stretch vibrational bands and permanent electric dipole moments for several [emim][Tf_2N] low energy isomers. The helium nanodroplet infrared spectrum of this species provides rather definitive support to the previously suggested vaporization mechanism of ionic liquids. [emim][Tf_2N] is defined as 1-ethyl-3-methylimidazolium[bis(trifluoromethylsulfonyl)imide] Armstrong, J.P.; Hurst, C.; Jones, R. G.; Licence, P.; Lovelock, K. R. J.; Satterley, C. J.; Villar-Garcia, I. J. Physical Chemistry Chemical Physics 2007, 9, 982. Strasser, D.; Goulay, F.; Belau, L.; Kostko, O.; Koh, C.; Chambreau, S. D.; Vaghjiani, G. L.; Ahmed, M.; Leone, S. R. Journal of Physical Chemistry A 2010, 114, 879. Strasser, D.; Goulay, F.; Kelkar, M. S.; Maginn, E. J.; Leone, S. R. Journal of Physical Chemistry A 2007, 111, 3191. Chambreau, S. D.; Vaghjiani, G. L.; To, A.; Koh, C.; Strasser, D.; Kostko, O.; Leone, S. R. Journal of Physical Chemistry B 2010, 114, 1361. Maginn, E. J.; Kelkar, M. S. Journal of Physical Chemistry B 2007, 111, 9424.

  8. Covalent magnetism and magnetic impurities.

    Science.gov (United States)

    Gruber, C; Bedolla, P O; Mohn, P

    2013-05-08

    We use the model of covalent magnetism and its application to magnetic insulators applied to the case of insulating carbon doped BaTiO3. Since the usual Stoner mechanism is not applicable we study the possibility of the formation of magnetic order based on a mechanism favoring singly occupied orbitals. On the basis of our model parameters we formulate a criterion similar to the Stoner criterion but also valid for insulators. We describe the model of covalent magnetism using a molecular orbital picture and determine the occupation numbers for spin-up and spin-down states. Our model allows a simulation of the results of our ab initio calculations for E(ℳ) which are found to be in very good agreement.

  9. Optimization of a ribbon diode with magnetic insulation for increasing the current density in a high-current relativistic electron beam

    Science.gov (United States)

    Astrelin, V. T.; Arzhannikov, A. V.; Burdakov, A. V.; Sinitskii, S. L.; Stepanov, V. D.

    2009-05-01

    The geometry of the ribbon diode of the U-2 accelerator is optimized to increase both the current density and the total current of the relativistic electron beam for its subsequent injection into the plasma of a multimirror GOL-3 trap. Beam simulation in the diode was performed using the POISSON-2 applied software modified on the basis of the results obtained using the theory of a planar diode in an inclined magnetic field. As a result of the optimization, the diode geometry and the magnetic field configuration were found that should provide a factor of 1.5-2 increase in the current density in experiments with a small angular divergence of electron velocities.

  10. Estimation of Theaflavins (TF) and Thearubigins (TR) Ratio in Black Tea Liquor Using Electronic Vision System

    Science.gov (United States)

    Akuli, Amitava; Pal, Abhra; Ghosh, Arunangshu; Bhattacharyya, Nabarun; Bandhopadhyya, Rajib; Tamuly, Pradip; Gogoi, Nagen

    2011-09-01

    Quality of black tea is generally assessed using organoleptic tests by professional tea tasters. They determine the quality of black tea based on its appearance (in dry condition and during liquor formation), aroma and taste. Variation in the above parameters is actually contributed by a number of chemical compounds like, Theaflavins (TF), Thearubigins (TR), Caffeine, Linalool, Geraniol etc. Among the above, TF and TR are the most important chemical compounds, which actually contribute to the formation of taste, colour and brightness in tea liquor. Estimation of TF and TR in black tea is generally done using a spectrophotometer instrument. But, the analysis technique undergoes a rigorous and time consuming effort for sample preparation; also the operation of costly spectrophotometer requires expert manpower. To overcome above problems an Electronic Vision System based on digital image processing technique has been developed. The system is faster, low cost, repeatable and can estimate the amount of TF and TR ratio for black tea liquor with accuracy. The data analysis is done using Principal Component Analysis (PCA), Multiple Linear Regression (MLR) and Multiple Discriminate Analysis (MDA). A correlation has been established between colour of tea liquor images and TF, TR ratio. This paper describes the newly developed E-Vision system, experimental methods, data analysis algorithms and finally, the performance of the E-Vision System as compared to the results of traditional spectrophotometer.

  11. Gas insulated substations

    CERN Document Server

    2014-01-01

    This book provides an overview on the particular development steps of gas insulated high-voltage switchgear, and is based on the information given with the editor's tutorial. The theory is kept low only as much as it is needed to understand gas insulated technology, with the main focus of the book being on delivering practical application knowledge. It discusses some introductory and advanced aspects in the meaning of applications. The start of the book presents the theory of Gas Insulated Technology, and outlines reliability, design, safety, grounding and bonding, and factors for choosing GIS. The third chapter presents the technology, covering the following in detail: manufacturing, specification, instrument transformers, Gas Insulated Bus, and the assembly process. Next, the book goes into control and monitoring, which covers local control cabinet, bay controller, control schemes, and digital communication. Testing is explained in the middle of the book before installation and energization. Importantly, ...

  12. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  13. Vacuum foil insulation system

    Science.gov (United States)

    Hanson, John P.; Sabolcik, Rudolph E.; Svedberg, Robert C.

    1976-11-16

    In a multifoil thermal insulation package having a plurality of concentric cylindrical cups, means are provided for reducing heat loss from the penetration region which extends through the cups. At least one cup includes an integral skirt extending from one end of the cup to intersection with the penetration means. Assembly of the insulation package with the skirted cup is facilitated by splitting the cup to allow it to be opened up and fitted around the other cups during assembly.

  14. Improved Sprayable Insulation

    Science.gov (United States)

    Hill, W. F.; Sharpe, M. H.; Lester, C. N.; Echols, Sherman; Simpson, W. G.; Lambert, J. D.; Norton, W. F.; Mclemore, J. P.; Patel, A. K.; Patel, S. V.; hide

    1992-01-01

    MSA-2 and MSA-2A, two similar improved versions of Marshall sprayable ablator, insulating material developed at Marshall Space Flight Center to replace both sheets of cork and MSA-1. Suitable for use on large vehicles and structures exposed to fire or other sources of heat by design or accident. Ablative insulation turns into strong char when exposed to high temperature; highly desireable property in original spacecraft application and possibly in some terrestrial applications.

  15. Parallelized preconditioned BiCGStab solution of sparse linear system equations in F-COBRA-TF

    International Nuclear Information System (INIS)

    Geemert, Rene van; Glück, Markus; Riedmann, Michael; Gabriel, Harry

    2011-01-01

    Recently, the in-house development of a preconditioned and parallelized BiCGStab solver has been pursued successfully in AREVA’s advanced sub-channel code F-COBRA-TF. This solver can be run either in a sequential computation mode on a single CPU, or in a parallel computation mode on multiple parallel CPUs. The developed procedure enables the computation of several thousands of successive sparse linear system solutions in F-COBRA-TF with acceptable wall clock run times. The current paper provides general information about F-COBRA-TF in terms of modeling capabilities and application areas, and points out where the relevance arises for the efficient iterative solution of sparse linear systems. Furthermore, the preconditioning and parallelization strategies in the developed BiCGStab iterative solution approach are discussed. The paper is concluded with a number of verification examples. (author)

  16. The Art and Skill of Delivering Culturally Responsive TF-CBT in Tanzania and Kenya

    Science.gov (United States)

    Kava, Christine M.; Akiba, Christopher F.; Lucid, Leah; Dorsey, Shannon

    2016-01-01

    Objective This study explored the facilitators, barriers, and strategies used to deliver a child mental health evidence-based treatment (EBT), trauma-focused cognitive behavioral therapy (TF-CBT), in a culturally responsive manner. In low- and middle-income countries most individuals with mental health problems do not receive treatment due to a shortage of mental health professionals. One approach to addressing this problem is task-sharing, in which lay counselors are trained to deliver mental health treatment. Combining this approach with a focus on EBT provides a strategy for bridging the mental health treatment gap. However, little is known how about western-developed EBTs are delivered in a culturally responsive manner. Method Semistructured qualitative interviews were conducted with 12 TF-CBT lay counselors involved in a large randomized controlled trial of TF-CBT in Kenya and Tanzania. An inductive approach was used to analyze the data. Results Lay counselors described the importance of being responsive to TF-CBT participants’ customs, beliefs, and socioeconomic conditions and highlighted the value of TF-CBT for their community. They also discussed the importance of partnering with other organizations to address unmet socioeconomic needs. Conclusion The findings from this study provide support for the acceptability and appropriateness of TF-CBT as a treatment approach for improving child mental health. Having a better understanding of the strategies used by lay counselors to ensure that treatment is relevant to the cultural and socioeconomic context of participants can help to inform the implementation of future EBTs. PMID:27414470

  17. Whole genome shotgun sequence of Bacillus amyloliquefaciens TF28, a biocontrol entophytic bacterium.

    Science.gov (United States)

    Zhang, Shumei; Jiang, Wei; Li, Jing; Meng, Liqiang; Cao, Xu; Hu, Jihua; Liu, Yushuai; Chen, Jingyu; Sha, Changqing

    2016-01-01

    Bacillus amyloliquefaciens TF28 is a biocontrol endophytic bacterium that is capable of inhibition of a broad range of plant pathogenic fungi. The strain has the potential to be developed into a biocontrol agent for use in agriculture. Here we report the whole-genome shotgun sequence of the strain. The genome size of B. amyloliquefaciens TF28 is 3,987,635 bp which consists of 3754 protein-coding genes, 65 tandem repeat sequences, 47 minisatellite DNA, 2 microsatellite DNA, 63 tRNA, 7rRNA, 6 sRNA, 3 prophage and CRISPR domains.

  18. Witten effect in a crystalline topological insulator

    International Nuclear Information System (INIS)

    Rosenberg, G.; Franz, M.

    2010-01-01

    It has been noted a long time ago that a term of the form θ(e 2 /2πh)B·E may be added to the standard Maxwell Lagrangian without modifying the familiar laws of electricity and magnetism. θ is known to particle physicists as the 'axion' field and whether or not it has a nonzero expectation value in vacuum remains a fundamental open question of the standard model. A key manifestation of the axion term is the Witten effect: a unit magnetic monopole placed inside a medium with θ≠0 is predicted to bind a (generally fractional) electric charge -e(θ/2π+n) with n integer. Here we conduct a test of the Witten effect based on the recently established fact that the axion term with θ=π emerges naturally in the description of the electromagnetic response of a class of crystalline solids called topological insulators--materials distinguished by strong spin-orbit coupling and nontrivial band structures. Using a simple physical model for a topological insulator we demonstrate the existence of a fractional charge bound to a monopole by an explicit numerical calculation. We also propose a scheme for generating an ''artificial'' magnetic monopole in a topological insulator film that may be used to facilitate an experimental test of Witten's prediction.

  19. Topological Field Theory of Time-Reversal Invariant Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiao-Liang; Hughes, Taylor; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

    2010-03-19

    We show that the fundamental time reversal invariant (TRI) insulator exists in 4 + 1 dimensions, where the effective field theory is described by the 4 + 1 dimensional Chern-Simons theory and the topological properties of the electronic structure is classified by the second Chern number. These topological properties are the natural generalizations of the time reversal breaking (TRB) quantum Hall insulator in 2 + 1 dimensions. The TRI quantum spin Hall insulator in 2 + 1 dimensions and the topological insulator in 3 + 1 dimension can be obtained as descendants from the fundamental TRI insulator in 4 + 1 dimensions through a dimensional reduction procedure. The effective topological field theory, and the Z{sub 2} topological classification for the TRI insulators in 2+1 and 3+1 dimensions are naturally obtained from this procedure. All physically measurable topological response functions of the TRI insulators are completely described by the effective topological field theory. Our effective topological field theory predicts a number of novel and measurable phenomena, the most striking of which is the topological magneto-electric effect, where an electric field generates a magnetic field in the same direction, with an universal constant of proportionality quantized in odd multiples of the fine structure constant {alpha} = e{sup 2}/hc. Finally, we present a general classification of all topological insulators in various dimensions, and describe them in terms of a unified topological Chern-Simons field theory in phase space.

  20. Thermal analysis of the cryostat feed through for the ITER Tokamak TF feeder

    Science.gov (United States)

    Zhang, Shanwen; Song, Yuntao; Lu, Kun; Wang, Zhongwei; Zhang, Jianfeng; Qin, Yongfa

    2017-04-01

    In Tokamaks, the toroidal field (TF) coil feeder is an important component that is used to supply the cryogens and electrical power for the TF coils. As a part of the TF feeder, the cryostat-feed through (CFT) is subject to low temperatures of 9 and 80 K inside and room temperature of 300 K outside. Based on the features of the International Thermonuclear Experimental Reactor TF feeder, the thermal performance of the CFT under the nominal conditions is studied. Taking into account the conductive, convective and radiation heat transfer, the finite element model of the CFT is built. Transient thermal analysis is performed to determine the temperatures of the CFT on the 9th day of cooldown. The model is assessed by comparing the cooling curves of the CFT after 9 days. If the simulation and experimental results are the same, the finite element model can be considered as calibrated. The model predicts that the cooling time will be approximately 26 days and the temperature distribution and heat load of the main components are obtained when the CFT reaches thermal equilibrium. This study provides a valid quantitative characterization of the CFT design.

  1. BOREAS TF-1 SSA-OA Understory Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Black, T. Andrew; Chen, Z.; Nesic, Zoran

    2000-01-01

    The BOREAS TF-1 team collected energy, carbon dioxide, and momentum flux data under the canopy along with meteorological and soils data at the BOREAS SSA-OA site from mid-October to mid-November of 1993 and throughout all of 1994. The data are available in tabular ASCII files.

  2. BOREAS TF-9 SSA-OBS Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Massheder, Jonathan M.; Moncrieff, John B.; Rayment, Mark B.; Jarvis, Paul G.

    2000-01-01

    The BOREAS TF-9 team collected energy, carbon dioxide, and water vapor flux data at the BOREAS SSA-OBS site during the growing season of 1994 and most of the year for 1996. From the winter of 1995 to 1996, soil temperature data were also collected and provided. The data are available in tabular ASCII files.

  3. BOREAS TF-8 NSA-OJP Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Moore, Kathleen E.; Fitzjarrald, David R.

    2000-01-01

    The BOREAS TF-8 team collected energy, CO2, and water vapor flux data at the BOREAS NSA-OJP site during the growing season of 1994 and most of the year for 1996. The data are available in tabular ASCII files.

  4. BOREAS TF-3 NSA-OBS Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Wofsy, Steven; Sutton, Doug; Goulden, Mike; Hall, Forrest G. (Editor); Huemmrich, Karl (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Tower Flux (BOREAS TF-3) team collected tower flux, surface meteorological, and soil temperature data at the BOREAS Northern Study Area-Old Black Spruce (NSA-OBS) site continuously from the March 1994 through October 1996. The data are available in tabular ASCII files.

  5. BOREAS TF-1 SSA-OA Tower Flux, Meteorological, and Soil Temperature Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Huemmrich, Karl (Editor); Black, T. Andrew; Chen, Z.; Nesic, Zoran

    2000-01-01

    The BOREAS TF-1 team collected energy, carbon dioxide, and momentum flux data above the canopy along with meteorological and soils data at the BOREAS SSA-OA site from mid-April to the end of the year for 1996. The data are available in tabular ASCII files.

  6. Peringkasan Sentimen Esktraktif di Twitter Menggunakan Hybrid TF-IDF dan Cosine Similarity

    Directory of Open Access Journals (Sweden)

    Devid Haryalesmana Wahid

    2016-07-01

    Full Text Available The using of Twitter by selebrities has become a new trend of impression management strategy. Mining public reaction in social media is a good strategy to obtain feedbacks, but extracting it are not trivial matter. Reads hundred of tweets while determine their sentiment polarity are time consuming. Extractive sentiment summarization machine are needed to address this issue. Previous research generally do not include sentiment information contained in a tweet as weight factor, as a results only general topics of discussion are extracted. This research aimed to do an extractive sentiment summarization on both positive and negative sentiment mentioning Indonesian selebrity, Agnes Monica, by combining SentiStrength, Hybrid TF-IDF, and Cosine Similarity. SentiStrength is used to obtain sentiment strength score and classify tweet as a positive, negative or neutral. The summarization of posisitve and negative sentiment can be done by rank tweets using Hybrid TF-IDF summarization and sentiment strength score as additional weight then removing similar tweet by using Cosine Similarity. The test results showed that the combination of SentiStrength, Hybrid TF-IDF, and Cosine Similarity perform better than using Hybrid TF-IDF only, given an average 60% accuracy and 62% f-measure. This is due to the addition of sentiment score as a weight factor in sentiment summ­ari­zation.

  7. A study on nuclear heat load tolerable for NET/TF coils cooled by internal flow of helium II

    International Nuclear Information System (INIS)

    Hofmann, A.

    1988-02-01

    NbTi cables cooled by internal flow of superfluid helium are considered an option for the design of NET/TF coils with about 11 T peak fields. Starting from an available winding cross section of 0.61x0.61 m 2 for a 8 MA turns coil made of a 16 kA conductor it is shown that sufficient hydraulic cross section can be provided within such cables to remove the expected thermal load resulting from nuclear heating with exponential decay from inboard to outboard side of the winding. The concept is a pancake type coil with 1.8 K helium fed-in the high field region of each pancake. The temperature distribution within such coils is calculated, and the local safety margin is determined from temperature and field. The calculation takes account of nuclear and a.c. heating, and of thermal conductance between the individual layers and the coil casing. It is shown that operation with 1.8 K inlet and about 3 K outlet temperature is possible. The electrical insulation with about 0.5 mm thickness proves to provide sufficient thermal insulation. No additional thermal shield is required between the coil casing and the winding package. Two different types of conductors are being considered: a) POLO type cable with quadratic cross section and a central circular coolant duct, and b) an LCT type cable with two conductors wound in hand. Both concepts with about 500 m length of the cooland channels are shown to meet the requirements resulting from a peak nuclear heat load of 0.3 mW/cm 3 in the inboard turns. The hydraulic diameters are sufficient to operate each coils with self-sustained fountain effect pumps. Even appreciably higher heat loads with up to 3 mW/cm 3 of nuclear heating can be tolerated for the POLO type cable when the hydraulic diameter is enlarged to its maximum of 17 mm. (orig.) [de

  8. Tunnel Magneto Resistance of Fe/Insulator/Fe

    Science.gov (United States)

    Aryee, Dennis; Seifu, Dereje

    Tri-layer thin films of Fe/Insulator/Fe were synthesized using magnetron DC/ RF sputtering with MgO insulator and Bi2Te3 topological insulators as middle buffer layer. The multi-layered samples thus produced were studied using in-house built magneto-optic Kerr effect (MOKE) instrument, vibrating sample magnetometer (VSM), torque magnetometer (TMM), AFM, MFM, and magneto-resistance (MR). This system, that is Fe/Insulator/Fe on MgO(100) substrate, is a well-known tunnel magneto resistance (TMR) structure often used in magnetic tunnel junction (MTJ) devices. TMR effect is a method by which MTJs are used in developing magneto-resistive random access memory (MRAM), magnetic sensors, and novel logic devices. The main purpose behind this research is to measure the magnetic anisotropy of Fe/Insulator /Fe structure and correlate it to magneto-resistance. In this presentation, we will present results from MOKE, VSM, TMM, AFM, MFM, and MR studies of Fe/Insulator/Fe on MgO(100). We would like to acknowledge support by NSF-MRI-DMR-1337339.

  9. Condensation in insulated homes

    Energy Technology Data Exchange (ETDEWEB)

    Wiley, R A

    1978-05-28

    A research proposal on condensation in insulated homes is presented. Information is provided on: justification for condensation control; previous work and present outlook (good vapor barrier, condensation and retrofit insulation, vapor barrier decreases condensation, brick-veneer walls, condensation in stress-skin panels, air-conditioned buildings, retrofitting for conservation, study on mobile homes, high indoor relative humidity, report on various homes); and procedure (after funding has been secured). Measures are briefly described on opening walls, testing measures, and retrofitting procedures. An extensive bibliography and additional informative citations are included. (MCW)

  10. Flux pumping for non-insulated and metal-insulated HTS coils

    Science.gov (United States)

    Ma, Jun; Geng, Jianzhao; Coombs, T. A.

    2018-01-01

    High-temperature superconducting (HTS) coils wound from coated conductors without turn-to-turn insulation (non-insulated (NI) coils) have been proven with excellent electrical and thermal performances. However, the slow charging of NI coils has been a long-lasting problem. In this work, we explore using a transformer-rectifier HTS flux pump to charge an NI coil and a metal-insulated coil. The charging performance comparison is made between different coils. Comprehensive study is done to thoroughly understand the electrical-magnetic transience in charging these coils. We will show that the low-voltage high-current flux pump is especially suitable for charging NI coils with very low characteristic resistance.

  11. Metal-insulator transition in vanadium dioxide

    International Nuclear Information System (INIS)

    Zylbersztejn, A.; Mott, N.F.

    1975-01-01

    The basic physical parameters which govern the metal-insulator transition in vanadium dioxide are determined through a review of the properties of this material. The major importance of the Hubbard intra-atomic correlation energy in determining the insulating phase, which was already evidence by studies of the magnetic properties of V 1 -/subx/Cr/subx/O 2 alloys, is further demonstrated from an analysis of their electrical properties. An analysis of the magnetic susceptibility of niobium-doped VO 2 yields a picture for the current carrier in the low-temperature phase in which it is accompanied by a spin cloud (owing to Hund's-rule coupling), and has therefore an enhanced mass (m approx. = 60m 0 ). Semiconducting vanadium dioxide turns out to be a borderline case for a classical band-transport description; in the alloys at high doping levels, Anderson localization with hopping transport can take place. Whereas it is shown that the insulating phase cannot be described correctly without taking into account the Hubbard correlation energy, we find that the properties of the metallic phase are mainly determined by the band structure. Metallic VO 2 is, in our view, similar to transition metals like Pt or Pd: electrons in a comparatively wide band screening out the interaction between the electrons in a narrow overlapping band. The magnetic susceptibility is described as exchange enhanced. The large density of states at the Fermi level yields a substantial contribution of the entropy of the metallic electrons to the latent heat. The crystalline distortion removes the band degeneracy so that the correlation energy becomes comparable with the band width and a metal-insulator transition takes place

  12. Insulation Reformulation Development

    Science.gov (United States)

    Chapman, Cynthia; Bray, Mark

    2015-01-01

    The current Space Launch System (SLS) internal solid rocket motor insulation, polybenzimidazole acrylonitrile butadiene rubber (PBI-NBR), is a new insulation that replaced asbestos-based insulations found in Space Shuttle heritage solid rocket boosters. PBI-NBR has some outstanding characteristics such as an excellent thermal erosion resistance, low thermal conductivity, and low density. PBI-NBR also has some significant challenges associated with its use: Air entrainment/entrapment during manufacture and lay-up/cure and low mechanical properties such as tensile strength, modulus, and fracture toughness. This technology development attempted to overcome these challenges by testing various reformulated versions of booster insulation. The results suggest the SLS program should continue to investigate material alternatives for potential block upgrades or use an entirely new, more advanced booster. The experimental design was composed of a logic path that performs iterative formulation and testing in order to maximize the effort. A lab mixing baseline was developed and documented for the Rubber Laboratory in Bldg. 4602/Room 1178.

  13. Exploring Homeowners’ Insulation Activity

    NARCIS (Netherlands)

    Friege, J; Holtz, G; Chappin, E.J.L.

    2016-01-01

    Insulating existing buildings offers great potential for reducing greenhouse gas emissions and meeting Germany’s climate protection targets. Previous research suggests that, since homeowners’ decision-making processes are inadequately understood as yet, today’s incentives aiming at increasing

  14. Conducting and insulating materials

    OpenAIRE

    Bolotinha, Manuel

    2016-01-01

    Conducting materials may be classified into three groups: conductors, semiconductors and imperfect insulators. This section will cover only conductors. In general, metals and alloys are conductors of electricity. The most common metals used in electricity are copper, aluminium and their alloys. info:eu-repo/semantics/publishedVersion

  15. Super insulating aerogel glazing

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Jensen, Karsten Ingerslev; Kristiansen, Finn Harken

    2005-01-01

    This paper describes the application results of a previous and current EU-project on super insulating glazing based on monolithic silica aerogel. Prototypes measuring approx. 55´55 cm2 have been made with 15 mm evacuated aerogel between two layers of low-iron glass. Anti-reflective treatment...

  16. Fractional Chern Insulator

    Directory of Open Access Journals (Sweden)

    N. Regnault

    2011-12-01

    Full Text Available Chern insulators are band insulators exhibiting a nonzero Hall conductance but preserving the lattice translational symmetry. We conclusively show that a partially filled Chern insulator at 1/3 filling exhibits a fractional quantum Hall effect and rule out charge-density-wave states that have not been ruled out by previous studies. By diagonalizing the Hubbard interaction in the flat-band limit of these insulators, we show the following: The system is incompressible and has a 3-fold degenerate ground state whose momenta can be computed by postulating an generalized Pauli principle with no more than 1 particle in 3 consecutive orbitals. The ground-state density is constant, and equal to 1/3 in momentum space. Excitations of the system are fractional-statistics particles whose total counting matches that of quasiholes in the Laughlin state based on the same generalized Pauli principle. The entanglement spectrum of the state has a clear entanglement gap which seems to remain finite in the thermodynamic limit. The levels below the gap exhibit counting identical to that of Laughlin 1/3 quasiholes. Both the 3 ground states and excited states exhibit spectral flow upon flux insertion. All the properties above disappear in the trivial state of the insulator—both the many-body energy gap and the entanglement gap close at the phase transition when the single-particle Hamiltonian goes from topologically nontrivial to topologically trivial. These facts clearly show that fractional many-body states are possible in topological insulators.

  17. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  18. Topological insulator infrared pseudo-bolometer with polarization sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Peter Anand

    2017-10-25

    Topological insulators can be utilized in a new type of infrared photodetector that is intrinsically sensitive to the polarization of incident light and static magnetic fields. The detector isolates single topological insulator surfaces and allows light collection and exposure to static magnetic fields. The wavelength range of interest is between 750 nm and about 100 microns. This detector eliminates the need for external polarization selective optics. Polarization sensitive infrared photodetectors are useful for optoelectronics applications, such as light detection in environments with low visibility in the visible wavelength regime.

  19. Quantum magnetotransport properties of ultrathin topological insulator films

    KAUST Repository

    Tahir, M.

    2013-01-30

    We study the quantum magnetotransport in ultrathin topological insulator films in an external magnetic field considering hybridization between the upper and lower surfaces of the film. We investigate the two possible mechanisms for splitting of Landau levels, Zeeman and hybridization effects, and show that their interplay leads to minima in the collisional and Hall conductivities with a metal-to-insulator phase transition at the charge neutrality point. Hall plateaus arise at unusual multiples of e2/h . Evidence of a quantum phase transition for the zeroth and splitting of the higher Landau levels is found from the temperature and magnetic field dependences of the transport.

  20. The design and the manufacturing process of the superconducting toroidal field magnet system for EAST device

    International Nuclear Information System (INIS)

    Chen Wenge; Pan Yannian; Chen Zuoming; Wei Jin

    2008-01-01

    The toroidal field (TF) magnet system of EAST (HT-7U), which consists of 16 superconducting coils enclosed in steel cases, has been manufactured to generate the magnetic field of 3.5 T at the plasma center to maintain plasma in a tokamak configuration with a current up to 1 MA. The TF coils have an approximately D-shape geometry of 2.6 m wide and 4.0 m high, and operate at a maximum field of 5.8 T. The conductor used in the TF coil is NbTi/Cu cable-in conduit (CIC) conductor, and its operating current is 14.3 kA. In March 2006, the first cooling down of the EAST device has been carried out successfully. The total of TF magnet system has been cooled down from room temperature to 4.5 K, and the TF system has been energized up to 8.2 kA with 5 A/s ramp rate. In September 2006, full performances of the TF magnet system have been reached, and the device of EAST has delivered its first plasma. In addition, the TF magnet system has been routinely operated with a current maintained constant on a whole day basis, for a preliminary program of more than 500 shots. In this paper, the main parts of the design, developmental tests, and the fabrication and assembly of TF coils are described in detail

  1. Acquisition of He3 Cryostat Insert for Experiments on Topological Insulators

    Science.gov (United States)

    2016-02-03

    facilitated transport experiments on topological insulators and Dirac and Weyl semimetals. These experiments resulted in several notable achievements and...Approved for Public Release; Distribution Unlimited Final Report: Acquisition of He3 Cryostat Insert for Experiments on Topological Insulators. The views...Experiments on Topological Insulators. Report Title The award enabled the PI to acquire a complete cryogenic system with a 9-Tesla superconducting magnet. The

  2. Single Document Automatic Text Summarization using Term Frequency-Inverse Document Frequency (TF-IDF

    Directory of Open Access Journals (Sweden)

    Hans Christian

    2016-12-01

    Full Text Available The increasing availability of online information has triggered an intensive research in the area of automatic text summarization within the Natural Language Processing (NLP. Text summarization reduces the text by removing the less useful information which helps the reader to find the required information quickly. There are many kinds of algorithms that can be used to summarize the text. One of them is TF-IDF (TermFrequency-Inverse Document Frequency. This research aimed to produce an automatic text summarizer implemented with TF-IDF algorithm and to compare it with other various online source of automatic text summarizer. To evaluate the summary produced from each summarizer, The F-Measure as the standard comparison value had been used. The result of this research produces 67% of accuracy with three data samples which are higher compared to the other online summarizers.

  3. Test Results of the First US ITER TF Conductor in SULTAN

    Energy Technology Data Exchange (ETDEWEB)

    Martovetsky, N N; Hatfield, D R; Miller, J R; Gung, C; Schultz, J S; Cheggour, N; Goodrich, L F; Bruzzone, P; Stepanov, B; Wesche, R; Seeber, B

    2008-08-18

    The US Domestic Agency is one of six parties supplying TF cable-in-conduit conductors (CICCs) for ITER. Previous tests have shown that measured performance of the TF CICCs can be much lower than expected from the strand properties at the projected uniaxial strain and that the cabling pattern may also be an important factor. Worst of all, voltage signals well below the expected critical surface could not be reliably interpreted or canceled, making test results very suspect. The TFUS1 sample was prepared to achieve multiple goals: (1) to ensure uniform current distribution and to eliminate parasitic voltage signals by improving joints, (2) to explore the potential benefits of a different cabling pattern for better support of strain-sensitive strands, and (3) to explore the source of voltage development in the cable through the use of innovative penetrating diagnostics. Test results of the first US-made samples are presented and discussed.

  4. Factors Associated with Clinician Participation in TF-CBT Post-workshop Training Components.

    Science.gov (United States)

    Pemberton, Joy R; Conners-Burrow, Nicola A; Sigel, Benjamin A; Sievers, Chad M; Stokes, Lauren D; Kramer, Teresa L

    2017-07-01

    For proficiency in an evidence-based treatment (EBT), mental health professionals (MHPs) need training activities extending beyond a one-time workshop. Using data from 178 MHPs participating in a statewide TF-CBT dissemination project, we used five variables assessed at the workshop, via multiple and logistic regression, to predict participation in three post-workshop training components. Perceived in-workshop learning and client-treatment mismatch were predictive of consultation call participation and case presentation respectively. Attitudes toward EBTs were predictive of trauma assessment utilization, although only with non-call participants removed from analysis. Productivity requirements and confidence in TF-CBT skills were not associated with participation in post-workshop activities.

  5. Two-phase interfacial area and flow regime modeling in FLOWTRAN-TF code

    International Nuclear Information System (INIS)

    Smith, F.G. III; Lee, S.Y.; Flach, G.P.; Hamm, L.L.

    1992-01-01

    FLOWTRAN-TF is a new two-component, two-phase thermal-hydraulics code to capture the detailed assembly behavior associated with loss-of-coolant accident analyses in multichannel assemblies of the SRS reactors. The local interfacial area of the two-phase mixture is computed by summing the interfacial areas contributed by each of three flow regimes. For smooth flow regime transitions, the code uses an interpolation technique in terms of component void fraction for each basic flow regime

  6. Mutation in Torenia fournieri Lind. UFO homolog confers loss of TfLFY interaction and results in a petal to sepal transformation.

    Science.gov (United States)

    Sasaki, Katsutomo; Yamaguchi, Hiroyasu; Aida, Ryutaro; Shikata, Masahito; Abe, Tomoko; Ohtsubo, Norihiro

    2012-09-01

    We identified a Torenia fournieri Lind. mutant (no. 252) that exhibited a sepaloid phenotype in which the second whorls were changed to sepal-like organs. This mutant had no stamens, and the floral organs consisted of sepals and carpels. Although the expression of a torenia class B MADS-box gene, GLOBOSA (TfGLO), was abolished in the 252 mutant, no mutation of TfGLO was found. Among torenia homologs such as APETALA1 (AP1), LEAFY (LFY), and UNUSUAL FLORAL ORGANS (UFO), which regulate expression of class B genes in Arabidopsis, only accumulation of the TfUFO transcript was diminished in the 252 mutant. Furthermore, a missense mutation was found in the coding region of the mutant TfUFO. Intact TfUFO complemented the mutant phenotype whereas mutated TfUFO did not; in addition, the transgenic phenotype of TfUFO-knockdown torenias coincided with the mutant phenotype. Yeast two-hybrid analysis revealed that the mutated TfUFO lost its ability to interact with TfLFY protein. In situ hybridization analysis indicated that the transcripts of TfUFO and TfLFY were partially accumulated in the same region. These results clearly demonstrate that the defect in TfUFO caused the sepaloid phenotype in the 252 mutant due to the loss of interaction with TfLFY. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

  7. Analysis of quench-vent pressures for present design of ITER [International Thermonuclear Experimental Reactor] TF [toroidal field] coils

    International Nuclear Information System (INIS)

    Slack, D.S.

    1989-01-01

    The International Thermonuclear Experimental Reactor (ITER) is a new tokamak design project with joint participation from Japan, the European Community, the Union of the Soviet Union, and the United States. This paper examines the effects of a quench within the toroidal field (TF) coils based on current ITER design. It is a preliminary, rough analysis. Its intent is to assist ITER designers while more accurate computer codes are being developed and to provide a check against these more rigorous solutions. Rigorous solutions to the quench problem are very complex involving three-dimensional heat transfer, extreme changes in heat capacities and copper resistivity, and varying flow dynamics within the conductors. This analysis addresses all these factors in an approximate way. The result is much less accurate than a rigorous analysis. Results here could be in error as much as 30 to 40 percent. However, it is believed that this paper can still be very useful to the coil designer. Coil pressures and temperatures vs time into a quench are presented. Rate of helium vent, energy deposition in the coil, and depletion of magnetic stored energy are also presented. Peak pressures are high (about 43 MPa). This is due to the very long vent path length (446 m), small hydraulic diameters, and high current densities associated with ITER's cable-in-conduit design. The effects of these pressures as well as the ability of the coil to be self protecting during a quench are discussed. 3 refs., 3 figs., 1 tab

  8. Prediction of TF target sites based on atomistic models of protein-DNA complexes

    Directory of Open Access Journals (Sweden)

    Collado-Vides Julio

    2008-10-01

    Full Text Available Abstract Background The specific recognition of genomic cis-regulatory elements by transcription factors (TFs plays an essential role in the regulation of coordinated gene expression. Studying the mechanisms determining binding specificity in protein-DNA interactions is thus an important goal. Most current approaches for modeling TF specific recognition rely on the knowledge of large sets of cognate target sites and consider only the information contained in their primary sequence. Results Here we describe a structure-based methodology for predicting sequence motifs starting from the coordinates of a TF-DNA complex. Our algorithm combines information regarding the direct and indirect readout of DNA into an atomistic statistical model, which is used to estimate the interaction potential. We first measure the ability of our method to correctly estimate the binding specificities of eight prokaryotic and eukaryotic TFs that belong to different structural superfamilies. Secondly, the method is applied to two homology models, finding that sampling of interface side-chain rotamers remarkably improves the results. Thirdly, the algorithm is compared with a reference structural method based on contact counts, obtaining comparable predictions for the experimental complexes and more accurate sequence motifs for the homology models. Conclusion Our results demonstrate that atomic-detail structural information can be feasibly used to predict TF binding sites. The computational method presented here is universal and might be applied to other systems involving protein-DNA recognition.

  9. Green insulation: hemp fibers

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2011-09-15

    Indian hemp (Cannabis indica) is known for its psychotropic values and it is banned in most countries. However, industrial hemp (Cannabis sativa) is known for its tough fibers. Several manufactures in Europe including, small niche players, have been marketing hemp insulation products for several years. Hemp is a low environmental impact material. Neither herbicide nor pesticide is used during the growth of hemp. The fibers are extracted in a waste-free and chemical-free mechanical process. Hemp can consume CO2 during its growth. In addition, hemp fiber can be disposed of harmlessly by composting or incineration at the end of its life. Hemp fibers are processed and treated only minimally to resist rot and fungal activity. There is little health risk when producing and installing the insulation, thanks to the absence of toxic additive. Its thermal resistance is comparable to mineral wool. But the development and marketing of hemp fibers may be restricted in North America.

  10. Beyond insulation and isolation

    DEFF Research Database (Denmark)

    Højlund, Marie Koldkjær

    2016-01-01

    Most research on the acoustic environment in the modern Western hospital identifies raised noise levels as the main causal explanation for ranking noise as a critical stressor for patients, relatives and staff. Therefore, the most widely used strategies to tackle the problem in practice are insul......Most research on the acoustic environment in the modern Western hospital identifies raised noise levels as the main causal explanation for ranking noise as a critical stressor for patients, relatives and staff. Therefore, the most widely used strategies to tackle the problem in practice...... are insulation and isolation strategies to reduce measurable and perceptual noise levels. However, these strategies do not actively support the need to feel like an integral part of the shared hospital environment, which is a key element in creating healing environments, according to the paradigm of Evidence...

  11. Insulated pipe clamp design

    International Nuclear Information System (INIS)

    Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

    1980-01-01

    Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. The design considerations and methods along with the development tests are presented. Special considerations to guard against adverse cracking of the insulation material, to maintain the clamp-pipe stiffness desired during a seismic event, to minimize clamp restraint on the pipe during normal pipe heatup, and to resist clamp rotation or spinning on the pipe are emphasized

  12. Super insulating aerogel glazing

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe; Jensen, Karsten Ingerslev; Kristiansen, Finn Harken

    2004-01-01

    form the weakest part of the thermal envelope with respect to heat loss coefficient, but on the other hand also play an important role for passive solar energy utilisation. For window orientations other than south, the net energy balance will be close to or below zero. However, the properties......Monolithic silica aerogel offers the possibility of combining super insulation and high solar energy transmittance, which has been the background for a previous and a current EU project on research and development of monolithic silica aerogel as transparent insulation in windows. Generally, windows...... of aerogel glazing will allow for a positive net energy gain even for north facing vertical windows in a Danish climate during the heating season. This means that high quality daylight can be obtained even with additional energy gain. On behalf of the partners of the two EU projects, results related...

  13. Compact vacuum insulation embodiments

    Science.gov (United States)

    Benson, D.K.; Potter, T.F.

    1992-04-28

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point' or line' contacts with the metal wall sheets. In the case of monolithic spacers that form line' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included. 26 figs.

  14. Compact vacuum insulation

    Science.gov (United States)

    Benson, D.K.; Potter, T.F.

    1993-01-05

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  15. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  16. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  17. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  18. Insulated pipe clamp design

    International Nuclear Information System (INIS)

    Anderson, M.J.; Hyde, L.L.; Wagner, S.E.; Severud, L.K.

    1980-01-01

    Thin wall large diameter piping for breeder reactor plants can be subjected to significant thermal shocks during reactor scrams and other upset events. On the Fast Flux Test Facility, the addition of thick clamps directly on the piping was undesired because the differential metal temperatures between the pipe wall and the clamp could have significantly reduced the pipe thermal fatigue life cycle capabilities. Accordingly, an insulated pipe clamp design concept was developed. 5 refs

  19. From data repositories to submission portals: rethinking the role of domain-specific databases in CollecTF.

    Science.gov (United States)

    Kılıç, Sefa; Sagitova, Dinara M; Wolfish, Shoshannah; Bely, Benoit; Courtot, Mélanie; Ciufo, Stacy; Tatusova, Tatiana; O'Donovan, Claire; Chibucos, Marcus C; Martin, Maria J; Erill, Ivan

    2016-01-01

    Domain-specific databases are essential resources for the biomedical community, leveraging expert knowledge to curate published literature and provide access to referenced data and knowledge. The limited scope of these databases, however, poses important challenges on their infrastructure, visibility, funding and usefulness to the broader scientific community. CollecTF is a community-oriented database documenting experimentally validated transcription factor (TF)-binding sites in the Bacteria domain. In its quest to become a community resource for the annotation of transcriptional regulatory elements in bacterial genomes, CollecTF aims to move away from the conventional data-repository paradigm of domain-specific databases. Through the adoption of well-established ontologies, identifiers and collaborations, CollecTF has progressively become also a portal for the annotation and submission of information on transcriptional regulatory elements to major biological sequence resources (RefSeq, UniProtKB and the Gene Ontology Consortium). This fundamental change in database conception capitalizes on the domain-specific knowledge of contributing communities to provide high-quality annotations, while leveraging the availability of stable information hubs to promote long-term access and provide high-visibility to the data. As a submission portal, CollecTF generates TF-binding site information through direct annotation of RefSeq genome records, definition of TF-based regulatory networks in UniProtKB entries and submission of functional annotations to the Gene Ontology. As a database, CollecTF provides enhanced search and browsing, targeted data exports, binding motif analysis tools and integration with motif discovery and search platforms. This innovative approach will allow CollecTF to focus its limited resources on the generation of high-quality information and the provision of specialized access to the data.Database URL: http://www.collectf.org/. © The Author(s) 2016

  20. A Follow-Up Study from a Multisite, Randomized Controlled Trial for Traumatized Children Receiving TF-CBT.

    Science.gov (United States)

    Jensen, Tine K; Holt, Tonje; Ormhaug, Silje M

    2017-11-01

    Trauma-focused cognitive behavioral therapy (TF-CBT) is the treatment of choice for traumatized youth, however, follow-up studies are scarce, and treatment effects for co-occurring depression show mixed findings. The aims of this study were to examine whether treatment effects of TF-CBT are maintained at 18 month follow-up and whether degree of co-occurring depression influences treatment effects. As rapid improvement in psychological functioning is warranted for youth, we also investigated whether the symptom trajectory was different for TF-CBT compared to therapy as usual (TAU). The sample consisted of 156 youth (M age = 15.05, 79.50% girls) randomly assigned to TF-CBT or TAU. The youth were assessed for posttraumatic stress symptoms (PTSS), depression, anxiety and general mental health symptoms. Mixed effects analyses followed the symptom courses over 5 time points. Youth receiving TF-CBT maintained their symptom improvement at 18 months follow-up with scores below clinical cut-of on all symptom measures. The most depressed youth had also a significant decline in symptoms that were maintained at follow-up. Symptom trajectories differed as the TF-CBT group reported a more rapid symptom reduction compared to the TAU condition. In the TAU condition, participants received 1.5 times the number of treatment sessions compared to the TF-CBT participants. After 18 months the groups were significantly different on general mental health symptoms only. In conclusion, youth receiving TF-CBT experienced more efficient improvement in trauma related symptoms than youth receiving TAU and these improvements were maintained after 18 months. Also youth experiencing serious co-occurring depression benefitted from TF-CBT.

  1. TF Target Mapper: A BLAST search tool for the identification of Transcription Factor target genes

    Directory of Open Access Journals (Sweden)

    van der Spek Peter

    2006-03-01

    Full Text Available Abstract Background In the current era of high throughput genomics a major challenge is the genome-wide identification of target genes for specific transcription factors. Chromatin immunoprecipitation (ChIP allows the isolation of in vivo binding sites of transcription factors and provides a powerful tool for examining gene regulation. Crosslinked chromatin is immunoprecipitated with antibodies against specific transcription factors, thus enriching for sequences bound in vivo by these factors in the immunoprecipitated DNA. Cloning and sequencing the immunoprecipitated sequences allows identification of transcription factor target genes. Routinely, thousands of such sequenced clones are used in BLAST searches to map their exact location in the genome and the genes located in the vicinity. These genes represent potential targets of the transcription factor of interest. Such bioinformatics analysis is very laborious if performed manually and for this reason there is a need for developing bioinformatic tools to automate and facilitate it. Results In order to facilitate this analysis we generated TF Target Mapper (Transcription Factor Target Mapper. TF Target Mapper is a BLAST search tool allowing rapid extraction of annotated information on genes around each hit. It combines sequence cleaning/filtering, pattern searching and BLAST searches with extraction of information on genes located around each BLAST hit and comparisons of the output list of genes or gene ontology IDs with user-implemented lists. We successfully applied and tested TF Target Mapper to analyse sequences bound in vivo by the transcription factor GATA-1. We show that TF Target Mapper efficiently extracted information on genes around ChIPed sequences, thus identifying known (e.g. α-globin and ζ-globin and potentially novel GATA-1 gene targets. Conclusion TF Target Mapper is a very efficient BLAST search tool that allows the rapid extraction of annotated information on the genes

  2. The spectral function for Mott insulating surfaces

    CERN Document Server

    Manuel, L O; Feiguin, A E; Trumper, A E

    2003-01-01

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the sq root 3 x sq root 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion approx 10-40 meV compared with the centre-of-mass spectra bandwidth approx 0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations.

  3. The spectral function for Mott insulating surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Manuel, L O [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina); Gazza, C J [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina); Feiguin, A E [Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA (United States); Trumper, A E [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina)

    2003-05-07

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the {radical}3 x{radical} 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion {approx}10-40 meV compared with the centre-of-mass spectra bandwidth {approx}0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations.

  4. The spectral function for Mott insulating surfaces

    International Nuclear Information System (INIS)

    Manuel, L O; Gazza, C J; Feiguin, A E; Trumper, A E

    2003-01-01

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the √3 x√ 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion ∼10-40 meV compared with the centre-of-mass spectra bandwidth ∼0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations

  5. Unconventional pairing in three-dimensional topological insulators with a warped surface state

    NARCIS (Netherlands)

    Vasenko, A. S.; Golubov, A. A.; Silkin, V. M.; Chulkov, E. V.

    2017-01-01

    We study the effect of the Fermi surface anisotropy (hexagonal warping) on the superconducting pair potential, induced in a three-dimensional topological insulator (TI) by proximity with an s-wave superconductor (S) in presence of a magnetic moment of a nearby ferromagnetic insulator (FI). In the

  6. Reentrant Metal-Insulator Transitions in Silicon -

    Science.gov (United States)

    Campbell, John William M.

    This thesis describes a study of reentrant metal -insulator transitions observed in the inversion layer of extremely high mobility Si-MOSFETs. Magneto-transport measurements were carried out in the temperature range 20mK-4.2 K in a ^3He/^4 He dilution refrigerator which was surrounded by a 15 Tesla superconducting magnet. Below a melting temperature (T_{M}~500 mK) and a critical electron density (n_{s }~9times10^{10} cm^{-2}), the Shubnikov -de Haas oscillations in the diagonal resistivity enormous maximum values at the half filled Landau levels while maintaining deep minima corresponding to the quantum Hall effect at filled Landau levels. At even lower electron densities the insulating regions began to spread and eventually a metal-insulator transition could be induced at zero magnetic field. The measurement of extremely large resistances in the milliKelvin temperature range required the use of very low currents (typically in the 10^ {-12} A range) and in certain measurements minimizing the noise was also a consideration. The improvements achieved in these areas through the use of shielding, optical decouplers and battery operated instruments are described. The transport signatures of the insulating state are considered in terms of two basic mechanisms: single particle localization with transport by variable range hopping and the formation of a collective state such as a pinned Wigner crystal or electron solid with transport through the motion of bound dislocation pairs. The experimental data is best described by the latter model. Thus the two dimensional electron system in these high mobility Si-MOSFETs provides the first and only experimental demonstration to date of the formation of an electron solid at zero and low magnetic fields in the quantum limit where the Coulomb interaction energy dominates over the zero point oscillation energy. The role of disorder in favouring either single particle localization or the formation of a Wigner crystal is explored by

  7. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  8. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  9. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  11. MiTF links Erk1/2 kinase and p21CIP1/WAF1 activation after UVC radiation in normal human melanocytes and melanoma cells

    Directory of Open Access Journals (Sweden)

    Liu Feng

    2010-08-01

    Full Text Available Abstract As a survival factor for melanocytes lineage cells, MiTF plays multiple roles in development and melanomagenesis. What role MiTF plays in the DNA damage response is currently unknown. In this report we observed that MiTF was phosphorylated at serine 73 after UVC radiation, which was followed by proteasome-mediated degradation. Unlike after c-Kit stimulation, inhibiting p90RSK-1 did not abolish the band shift of MiTF protein, nor did it abolish the UVC-mediated MiTF degradation, suggesting that phosphorylation on serine 73 by Erk1/2 is a key event after UVC. Furthermore, the MiTF-S73A mutant (Serine 73 changed to Alanine via site-directed mutagenesis was unable to degrade and was continuously expressed after UVC exposure. Compared to A375 melanoma cells expressing wild-type MiTF (MiTF-WT, cells expressing MiTF-S73A mutant showed less p21WAF1/CIP1 accumulation and a delayed p21WAF1/CIP1 recovery after UVC. Consequently, cells expressing MiTF-WT showed a temporary G1 arrest after UVC, but cells expressing MiTF-S73A mutant or lack of MiTF expression did not. Finally, cell lines with high levels of MiTF expression showed higher resistance to UVC-induced cell death than those with low-level MiTF. These data suggest that MiTF mediates a survival signal linking Erk1/2 activation and p21WAF1/CIP1 regulation via phosphorylation on serine 73, which facilitates cell cycle arrest. In addition, our data also showed that exposure to different wavelengths of UV light elicited different signal pathways involving MiTF.

  12. CERTIFICATION OF THE RADIATION RESISTANCE OF COIL INSULATION MATERIAL

    CERN Document Server

    Polinski, J; Bogdan, P

    2013-01-01

    The goal of the WP 7.2.1 sub-task of the EuCARD program has been to determine the Nb$_{3}$Sn based accelerator magnet coil electrical insulation resistance against irradiation, which will occur in future accelerators. The scope of the certification covers determination of mechanical, electrical and thermal properties changes due to irradiation. The report presents a selection of the insulation material candidates for future accelerator magnets as well as the definition of the radiation certification methodology with respect of radiation type, energy, doses and irradiation conditions. The test methods and results of the electrical and mechanical insulation materials properties degradation due to irradiation are presented. Thermal conductivity and Kapitza resistance at temperature range from 1.5 K to 2.0 K (superfluid helium conditions) are given.

  13. Influence of void defects on partial discharge behavior of superconducting busbar insulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunyu; Huang, Xiongyi, E-mail: huangxy@ipp.ac.cn; Lu, Kun; Li, Guoliang; Zhu, Haisheng; Wang, Jun; Wang, Cao; Dai, Zhiheng; Fang, Linlin; Song, Yuntao

    2017-06-15

    Highlights: • PD detection method was used to check the quality of the superconducting busbar insulation. • The samples with different void fraction were manufactured for comparing. • The discharge inception voltage, PRPD pattern was tested and studied for the samples with different void content. • The PD behaviors in oil bath and air condition were compared. - Abstract: For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

  14. Electrical insulating liquid: A review

    Science.gov (United States)

    Mahanta, Deba Kumar; Laskar, Shakuntala

    Insulating liquid plays an important role for the life span of the transformer. Petroleum-based mineral oil has become dominant insulating liquid of transformer for more than a century for its excellent dielectric and cooling properties. However, the usage of petroleum-based mineral oil, derived from a nonrenewable energy source, has affected the environment for its nonbiodegradability property. Therefore, researchers direct their attention to renewable and biodegradable alternatives. Palm fatty acid ester, coconut oil, sunflower oil, etc. are considered as alternatives to replace mineral oil as transformer insulation liquid. This paper gives an extensive review of different liquid insulating materials used in a transformer. Characterization of different liquids as an insulating material has been discussed. An attempt has been made to classify different insulating liquids-based on different properties.

  15. Electrical insulating liquid: A review

    Directory of Open Access Journals (Sweden)

    Deba Kumar Mahanta

    2017-08-01

    Full Text Available Insulating liquid plays an important role for the life span of the transformer. Petroleum-based mineral oil has become dominant insulating liquid of transformer for more than a century for its excellent dielectric and cooling properties. However, the usage of petroleum-based mineral oil, derived from a nonrenewable energy source, has affected the environment for its nonbiodegradability property. Therefore, researchers direct their attention to renewable and biodegradable alternatives. Palm fatty acid ester, coconut oil, sunflower oil, etc. are considered as alternatives to replace mineral oil as transformer insulation liquid. This paper gives an extensive review of different liquid insulating materials used in a transformer. Characterization of different liquids as an insulating material has been discussed. An attempt has been made to classify different insulating liquids-based on different properties.

  16. Single atom anisotropic magnetoresistance on a topological insulator surface

    KAUST Repository

    Narayan, Awadhesh

    2015-03-12

    © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our first-principles quantum transport calculations based on density functional theory for Mn on Bi2Se3 elucidate the underlying mechanism. We complement our findings with a two dimensional model valid for both single adatoms and magnetic clusters, which leads to a proposed device setup for experimental realization. Our results provide an explanation for the conflicting scattering experiments on magnetic adatoms on topological insulator surfaces, and reveal the real space spin texture around the magnetic impurity.

  17. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  18. Analysis of multilayer insulation between 80K and 300K

    International Nuclear Information System (INIS)

    Augustynowicz, S.D.; Demko, J.A.; Datskov, V.I.

    1993-07-01

    A model has been developed that can be used to determine the temperature distribution and heat transfer through a multilayer insulation (MLI) blanket. Predictions from the model were compared with a series of temperature measurements made during laboratory experiments and during a test of five superconducting magnets (dipoles) installed in a string and tested at Fermi National Accelerator Laboratory, FNAL (ER Test)

  19. Irradiation effects on organic insulators

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1986-01-01

    The overall objective of this work is to contribute to development of organic insulators having the cryogenic neutron irradiation resistance required for MFE systems utilizing superconducting magnet confinement. The system for producing standard 3.2-mm (0.125-in) diameter rod specimens discussed in previous reports has been further refined to permit the fabrication of both fiber-reinforced and heat-resin specimens from hot-melt resin systems. The method has been successfully used to produce very high quality specimens duplicating the G-11CR system and specimens from a variant of that system eliminating a boron-containing additive. We have also produced specimens from an epoxy system suitable for impregnation or potting operations and from a bismaleimide polyimide system. These materials will be used in the first irradiation program in the National Low Temperature Neutron Irradiation Facility (NLTNIF) reactor at Oak Ridge. We have refined the 4-K torsional shear test method for evaluating radiation degradation of the fiber-matrix interface and have developed a method of quantitatively measuring changes in fracture energy as a function of radiation dose. Cooperative work with laboratories in Japan and England in this area is continuing and plans are being formulated for joint production, irradiation, and testing of specimens

  20. Low Permeability Polyimide Insulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  1. Insulators: estructura y funciones

    OpenAIRE

    Fresán Salvo, Ujué

    2016-01-01

    [spa] Los insulators son complejos de DNA y proteínas, cuya función no solo consiste en impedir la comunicación enhancer-promotor y/o bloquear la expansión del silenciamiento de la heterocromatina como clásicamente se habían descrito. Median interacciones intra e intercromosomales, cuyo objetivo fmal es la organización del genoma en diferentes dominios, regulando por consiguiente las funciones del DNA. Uno de los objetivos de esta tesis fue la búsqueda de nuevas funciones de proteínas insulat...

  2. CardioTF, a database of deconstructing transcriptional circuits in the heart system.

    Science.gov (United States)

    Zhen, Yisong

    2016-01-01

    Information on cardiovascular gene transcription is fragmented and far behind the present requirements of the systems biology field. To create a comprehensive source of data for cardiovascular gene regulation and to facilitate a deeper understanding of genomic data, the CardioTF database was constructed. The purpose of this database is to collate information on cardiovascular transcription factors (TFs), position weight matrices (PWMs), and enhancer sequences discovered using the ChIP-seq method. The Naïve-Bayes algorithm was used to classify literature and identify all PubMed abstracts on cardiovascular development. The natural language learning tool GNAT was then used to identify corresponding gene names embedded within these abstracts. Local Perl scripts were used to integrate and dump data from public databases into the MariaDB management system (MySQL). In-house R scripts were written to analyze and visualize the results. Known cardiovascular TFs from humans and human homologs from fly, Ciona, zebrafish, frog, chicken, and mouse were identified and deposited in the database. PWMs from Jaspar, hPDI, and UniPROBE databases were deposited in the database and can be retrieved using their corresponding TF names. Gene enhancer regions from various sources of ChIP-seq data were deposited into the database and were able to be visualized by graphical output. Besides biocuration, mouse homologs of the 81 core cardiac TFs were selected using a Naïve-Bayes approach and then by intersecting four independent data sources: RNA profiling, expert annotation, PubMed abstracts and phenotype. The CardioTF database can be used as a portal to construct transcriptional network of cardiac development. Database URL: http://www.cardiosignal.org/database/cardiotf.html.

  3. tf_unet: Generic convolutional neural network U-Net implementation in Tensorflow

    Science.gov (United States)

    Akeret, Joel; Chang, Chihway; Lucchi, Aurelien; Refregier, Alexandre

    2016-11-01

    tf_unet mitigates radio frequency interference (RFI) signals in radio data using a special type of Convolutional Neural Network, the U-Net, that enables the classification of clean signal and RFI signatures in 2D time-ordered data acquired from a radio telescope. The code is not tied to a specific segmentation and can be used, for example, to detect radio frequency interference (RFI) in radio astronomy or galaxies and stars in widefield imaging data. This U-Net implementation can outperform classical RFI mitigation algorithms.

  4. Analysis of distortion data from TF30-P-3 mixed compression inlet test

    Science.gov (United States)

    King, R. W.; Schuerman, J. A.; Muller, R. G.

    1976-01-01

    A program was conducted to reduce and analyze inlet and engine data obtained during testing of a TF30-P-3 engine operating behind a mixed compression inlet. Previously developed distortion analysis techniques were applied to the data to assist in the development of a new distortion methodology. Instantaneous distortion techniques were refined as part of the distortion methodology development. A technique for estimating maximum levels of instantaneous distortion from steady state and average turbulence data was also developed as part of the program.

  5. Solvent extraction of Pu(IV) with TODGA in C6mimTf2N

    International Nuclear Information System (INIS)

    Xiaohong Huang; Qiuyue Zhang; Jinping Liu; Hui He; Wenbin Zhu; Xiaorong Wang

    2013-01-01

    Studies on the solvent extraction of Plutonium(Pu(IV)) from aqueous nitric acid by N,N,N'N'tetraoctyl-diglycolamide (TODGA) in 1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl) imide (C 6 mimTf 2 N) room temperature ionic liquid (RTIL) were carried out. It was found that Pu(IV) is extracted into RTIL phase as [Pu(NO 3 )(TODGA)] 3+ through cation exchange mechanism. Extraction reaction equation is obtained by the influence of acidity and extractant concentration, and the parameters of thermodynamic equilibrium constant was calculated. (author)

  6. Conference on heat mass transfer and properties of liquid metals TF-2002

    International Nuclear Information System (INIS)

    Efanov, A.D.; Kozlov, F.A.

    2003-01-01

    Results of the conference TF-2002 devoted to the combined approach to problems of harnessing liquid metals as coolants for NPU are presented. The conference takes place in Obninsk, 29 - 31 October, 2002. Papers of the conference involve items on thermal hydraulics, mass transfer and safety of NPU with liquid metal coolants, structure, physical and chemical properties of liquid metal and liquid metal solutions, decommissioning of units and ecology, application of liquid metals divorced with NPU. Most of the papers of the conference are devoted to the investigation into lead and lead-bismuth coolants [ru

  7. Compact vacuum insulation

    Science.gov (United States)

    Benson, D.K.; Potter, T.F.

    1992-10-27

    Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

  8. Wide gap Chern Mott insulating phases achieved by design

    Science.gov (United States)

    Guo, Hongli; Gangopadhyay, Shruba; Köksal, Okan; Pentcheva, Rossitza; Pickett, Warren E.

    2017-12-01

    Quantum anomalous Hall insulators, which display robust boundary charge and spin currents categorized in terms of a bulk topological invariant known as the Chern number (Thouless et al Phys. Rev. Lett. 49, 405-408 (1982)), provide the quantum Hall anomalous effect without an applied magnetic field. Chern insulators are attracting interest both as a novel electronic phase and for their novel and potentially useful boundary charge and spin currents. Honeycomb lattice systems such as we discuss here, occupied by heavy transition-metal ions, have been proposed as Chern insulators, but finding a concrete example has been challenging due to an assortment of broken symmetry phases that thwart the topological character. Building on accumulated knowledge of the behavior of the 3d series, we tune spin-orbit and interaction strength together with strain to design two Chern insulator systems with bandgaps up to 130 meV and Chern numbers C = -1 and C = 2. We find, in this class, that a trade-off between larger spin-orbit coupling and strong interactions leads to a larger gap, whereas the stronger spin-orbit coupling correlates with the larger magnitude of the Hall conductivity. Symmetry lowering in the course of structural relaxation hampers obtaining quantum anomalous Hall character, as pointed out previously; there is only mild structural symmetry breaking of the bilayer in these robust Chern phases. Recent growth of insulating, magnetic phases in closely related materials with this orientation supports the likelihood that synthesis and exploitation will follow.

  9. Strain-induced high-temperature perovskite ferromagnetic insulator.

    Science.gov (United States)

    Meng, Dechao; Guo, Hongli; Cui, Zhangzhang; Ma, Chao; Zhao, Jin; Lu, Jiangbo; Xu, Hui; Wang, Zhicheng; Hu, Xiang; Fu, Zhengping; Peng, Ranran; Guo, Jinghua; Zhai, Xiaofang; Brown, Gail J; Knize, Randy; Lu, Yalin

    2018-03-20

    Ferromagnetic insulators are required for many new magnetic devices, such as dissipationless quantum-spintronic devices, magnetic tunneling junctions, etc. Ferromagnetic insulators with a high Curie temperature and a high-symmetry structure are critical integration with common single-crystalline oxide films or substrates. So far, the commonly used ferromagnetic insulators mostly possess low-symmetry structures associated with a poor growth quality and widespread properties. The few known high-symmetry materials either have extremely low Curie temperatures (≤16 K), or require chemical doping of an otherwise antiferromagnetic matrix. Here we present compelling evidence that the LaCoO 3 single-crystalline thin film under tensile strain is a rare undoped perovskite ferromagnetic insulator with a remarkably high T C of up to 90 K. Both experiments and first-principles calculations demonstrate tensile-strain-induced ferromagnetism which does not exist in bulk LaCoO 3 The ferromagnetism is strongest within a nearly stoichiometric structure, disappearing when the Co 2+ defect concentration reaches about 10%. Significant impact of the research includes demonstration of a strain-induced high-temperature ferromagnetic insulator, successful elevation of the transition over the liquid-nitrogen temperature, and high potential for integration into large-area device fabrication processes. Copyright © 2018 the Author(s). Published by PNAS.

  10. Magnetohydrodynamic flow in ducts with discontinuous electrical insulation

    International Nuclear Information System (INIS)

    Mistrangelo, C.; Bühler, L.

    2015-01-01

    Highlights: • Liquid metal MHD flows in ducts with flow channel inserts. • Study of the influence of local interruption of electrical insulation. • 3D numerical simulations. - Abstract: In liquid metal blankets the interaction of the moving breeder with the intense magnetic field that confines the fusion plasma results in significant modifications of the velocity distribution and increased pressure drop compared to hydrodynamic flows. Those changes are due to the occurrence of electromagnetic forces that slow down the core flow and which are balanced by large driving pressure heads. The resulting magnetohydrodynamic (MHD) pressure losses are proportional to the electric current density induced in the fluid and they can be reduced by electrically decoupling the wall from the liquid metal. For applications to dual coolant blankets it is foreseen to loosely insert electrically insulating liners into the ducts. In long channels the insulation could consist of a number of shorter inserts, which implies a possible local interruption of the insulation. Three dimensional numerical simulations have been performed to investigate MHD flows in electrically well-conducting channels with internal discontinuous insulating inserts. The local jump in the electric conductivity of the duct wall results in induced 3D electric currents and related electromagnetic forces yielding additional pressure losses and increased velocity in boundary layers parallel to the magnetic field.

  11. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  12. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  13. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  14. THE STABILITY MONITORING OF THE MANUFACTURING PROCESS OF ELECTRICAL INSULATING SYSTEMS OF TRACTION ELECTRIC MACHINES

    Directory of Open Access Journals (Sweden)

    G. V. Bezprozvannych

    2017-12-01

    Full Text Available Introduction. Electrical insulation systems make up about 0.03 % of the traction electric machines (TEM mass, but they are of exceptional importance and affect the design capabilities and manufacturing techniques of electric machines, ultimately - on their specific weight and overall dimensions, on the reliability and durability of the TEM. Purpose. The monitoring of the stability of the manufacturing process of electrical insulating systems of the TEM based on the insulation resistance measurements. Methodology. The analysis of the manufacturing process is carried out for three versions of the case of insulation of the magnetic system of the DC traction electric motor. Practical value. Construction and analysis of special graphs (charts of individual values and cumulative sums of insulation resistance, sliding range MR allow to find out whether the technological process of manufacturing electric insulating systems of traction electric machines is in a statistically controllable state.

  15. Wall Insulation; BTS Technology Fact Sheet

    Energy Technology Data Exchange (ETDEWEB)

    Southface Energy Institute; Tromly, K.

    2000-11-07

    Properly sealed, moisture-protected, and insulated walls help increase comfort, reduce noise, and save on energy costs. This fact sheet addresses these topics plus advanced framing techniques, insulation types, wall sheathings, and steps for effective wall construction and insulation.

  16. Washing Off Polyurethane Foam Insulation

    Science.gov (United States)

    Burley, Richard K.; Fogel, Irving

    1990-01-01

    Jet of hot water removes material quickly and safely. Simple, environmentally sound technique found to remove polyurethane foam insulation from metal parts. Developed for (but not limited to) use during rebuilding of fuel system of Space Shuttle main engine, during which insulation must be removed for penetrant inspection of metal parts.

  17. Electric fields and electrical insulation

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    2002-01-01

    The adoption of a field-theoretical approach to problems arising in the framework of electrical insulation is discussed with reference to six main topics, which have been addressed over the last 30 years. These include uniform field electrodes, Green's differential equation, electrode surface......, it is amply demonstrated that such an approach can lead to significant progress in many areas of electrical insulation....

  18. Application of TF-IDF factor in the semantic analysis of a documentary collection

    Directory of Open Access Journals (Sweden)

    Andrés Vuotto

    2015-11-01

    Full Text Available Objective. This paper describes the application of a tool for the semantic analysis of a document collection based on the use of term frequency–inverse document frequency (TF – IDF. Methodology. A system based on PHP and MySQL database for the management of a thesaurus, the calculation of TF – IDF (as an indicator of semantic weight and for development a relevance tree (consisting of those concepts is developed most relevant issue analyzed. The tool was tested to the semantic analysis of a documentary collection of Psychology. Results. The system was able to identify the level of track presence: professional ethics, in a collection of documents Psychology program. Conclusions. The experience described confirms the viability of the tool for the semantic analysis of a documentary collection. It underlines the relevance and capacities of information professionals to develop this kind of tools for processing information. The authors suggests a special technical approach for use of scripts and information flows.

  19. Detailed design studies at CEA for JT-60SA TF coils

    Energy Technology Data Exchange (ETDEWEB)

    Decool, P., E-mail: patrick.decool@cea.fr [CEA, IRFM F-13108 St-Paul-Lez-Durance Cedex (France); Marechal, J.L.; Portafaix, C.; Lacroix, B.; Gros, G.; Verger, J.M. [CEA, IRFM F-13108 St-Paul-Lez-Durance Cedex (France)

    2011-10-15

    Following a first conceptual design activity in which the general design of the JT-60SA TF system was defined and frozen in agreement with all the participants in the project (CEA, ENEA, F4E), a second phase had to be launched to deal with the detailed design. In this paper, we present the work performed at CEA on the TF coil design during this second phase. Part of this work, concerns the determination of conductor hydraulic performances during operation as well as in factory. The thermohydraulic of the conductor was also assessed to confirm the need of helium inlets and a specific design was developed and qualified to be compatible with the available hydraulic performance of the cryoplant. The mechanical behavior is still to be assessed and qualified. Last but not least, the inner electrical joints of the coil have been modified with respect to the original twin-box design developed by CEA for the ITER coils in order to simplify the fabrication process. A dedicated qualification program for their manufacture is ongoing.

  20. Detailed design studies at CEA for JT-60SA TF coils

    International Nuclear Information System (INIS)

    Decool, P.; Marechal, J.L.; Portafaix, C.; Lacroix, B.; Gros, G.; Verger, J.M.

    2011-01-01

    Following a first conceptual design activity in which the general design of the JT-60SA TF system was defined and frozen in agreement with all the participants in the project (CEA, ENEA, F4E), a second phase had to be launched to deal with the detailed design. In this paper, we present the work performed at CEA on the TF coil design during this second phase. Part of this work, concerns the determination of conductor hydraulic performances during operation as well as in factory. The thermohydraulic of the conductor was also assessed to confirm the need of helium inlets and a specific design was developed and qualified to be compatible with the available hydraulic performance of the cryoplant. The mechanical behavior is still to be assessed and qualified. Last but not least, the inner electrical joints of the coil have been modified with respect to the original twin-box design developed by CEA for the ITER coils in order to simplify the fabrication process. A dedicated qualification program for their manufacture is ongoing.

  1. Solubility of tetrafluoromethane in the ionic liquid [hmim][Tf2N].

    Science.gov (United States)

    Kumełan, Jacek; Kamps, Alvaro Pérez-Salado; Tuma, Dirk; Yokozeki, Akimichi; Shiflett, Mark B; Maurer, Gerd

    2008-03-13

    Experimental results for the solubility of tetrafluoromethane (CF4, R14) in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N]) are presented for temperatures between 293.3 and 413.3 K, at pressures (gas molalities) up to 9.6 MPa (0.22 mol kg-1). The experimental results were determined with a high-pressure view-cell technique operating on the synthetic method. The experimental data were used to determine Henry's constant of tetrafluoromethane in [hmim][Tf2N]. The results for the Henry's constant (at zero pressure) are correlated (on the molality scale) within the experimental uncertainty (i.e., about 1.1%) by ln(k(0)(H,CF4)/MPa) = 7.537 - 893.8/(T/K) - 0.003977(T/K). Henry's law was also extended to describe the gas solubility at higher pressures. Furthermore, a cubic equation of state was used to correlate the gas solubility over the entire range of experimentally investigated temperature and pressure. Both methods proved suited for a reliable correlation of the new experimental data.

  2. Research on vacuum insulation for cryocables

    International Nuclear Information System (INIS)

    Graneau, P.

    1974-01-01

    Vacuum insulation, as compared with solid insulation, simplifies the construction of both resistive or superconducting cryogenic cables. The common vacuum space in the cable can furnish thermal insulation between the environment and the cryogenic coolant, provide electrical insulation between conductors, and establish thermal isolation between go- and return-coolant streams. The differences between solid and vacuum high voltage insulation are discussed, and research on the design, materials selection, and testing of vacuum insulated cryogenic cables is described

  3. Three-dimensional fractional topological insulators in coupled Rashba layers

    Science.gov (United States)

    Volpez, Yanick; Loss, Daniel; Klinovaja, Jelena

    2017-08-01

    We propose a model of three-dimensional topological insulators consisting of weakly coupled electron- and hole-gas layers with Rashba spin-orbit interaction stacked along a given axis. We show that in the presence of strong electron-electron interactions the system realizes a fractional strong topological insulator, where the rotational symmetry and condensation energy arguments still allow us to treat the problem as quasi-one-dimensional with bosonization techniques. We also show that if Rashba and Dresselhaus spin-orbit interaction terms are equally strong, by doping the system with magnetic impurities, one can bring it into the Weyl semimetal phase.

  4. Quantum phase transitions of a disordered antiferromagnetic topological insulator

    Science.gov (United States)

    Baireuther, P.; Edge, J. M.; Fulga, I. C.; Beenakker, C. W. J.; Tworzydło, J.

    2014-01-01

    We study the effect of electrostatic disorder on the conductivity of a three-dimensional antiferromagnetic insulator (a stack of quantum anomalous Hall layers with staggered magnetization). The phase diagram contains regions where the increase of disorder first causes the appearance of surface conduction (via a topological phase transition), followed by the appearance of bulk conduction (via a metal-insulator transition). The conducting surface states are stabilized by an effective time-reversal symmetry that is broken locally by the disorder but restored on long length scales. A simple self-consistent Born approximation reliably locates the boundaries of this so-called "statistical" topological phase.

  5. Cis-regulatory control of the nuclear receptor Coup-TF gene in the sea urchin Paracentrotus lividus embryo.

    Directory of Open Access Journals (Sweden)

    Lamprini G Kalampoki

    Full Text Available Coup-TF, an orphan member of the nuclear receptor super family, has a fundamental role in the development of metazoan embryos. The study of the gene's regulatory circuit in the sea urchin embryo will facilitate the placement of this transcription factor in the well-studied embryonic Gene Regulatory Network (GRN. The Paracentrotus lividus Coup-TF gene (PlCoup-TF is expressed throughout embryonic development preferentially in the oral ectoderm of the gastrula and the ciliary band of the pluteus stage. Two overlapping λ genomic clones, containing three exons and upstream sequences of PlCoup-TF, were isolated from a genomic library. The transcription initiation site was determined and 5' deletions and individual segments of a 1930 bp upstream region were placed ahead of a GFP reporter cassette and injected into fertilized P.lividus eggs. Module a (-532 to -232, was necessary and sufficient to confer ciliary band expression to the reporter. Comparison of P.lividus and Strongylocentrotus purpuratus upstream Coup-TF sequences, revealed considerable conservation, but none within module a. 5' and internal deletions into module a, defined a smaller region that confers ciliary band specific expression. Putative regulatory cis-acting elements (RE1, RE2 and RE3 within module a, were specifically bound by proteins in sea urchin embryonic nuclear extracts. Site-specific mutagenesis of these elements resulted in loss of reporter activity (RE1 or ectopic expression (RE2, RE3. It is proposed that sea urchin transcription factors, which bind these three regulatory sites, are necessary for spatial and quantitative regulation of the PlCoup-TF gene at pluteus stage sea urchin embryos. These findings lead to the future identification of these factors and to the hierarchical positioning of PlCoup-TF within the embryonic GRN.

  6. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  7. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  8. Quantum oscillations in insulators with neutral Fermi surfaces

    Science.gov (United States)

    Sodemann, Inti; Chowdhury, Debanjan; Senthil, T.

    2018-02-01

    We develop a theory of quantum oscillations in insulators with an emergent Fermi sea of neutral fermions minimally coupled to an emergent U(1 ) gauge field. As pointed out by Motrunich [Phys. Rev. B 73, 155115 (2006), 10.1103/PhysRevB.73.155115], in the presence of a physical magnetic field the emergent magnetic field develops a nonzero value leading to Landau quantization for the neutral fermions. We focus on the magnetic field and temperature dependence of the analog of the de Haas-van Alphen effect in two and three dimensions. At temperatures above the effective cyclotron energy, the magnetization oscillations behave similarly to those of an ordinary metal, albeit in a field of a strength that differs from the physical magnetic field. At low temperatures, the oscillations evolve into a series of phase transitions. We provide analytical expressions for the amplitude and period of the oscillations in both of these regimes and simple extrapolations that capture well their crossover. We also describe oscillations in the electrical resistivity of these systems that are expected to be superimposed with the activated temperature behavior characteristic of their insulating nature and discuss suitable experimental conditions for the observation of these effects in mixed-valence insulators and triangular lattice organic materials.

  9. Giant Edelstein effect in topological-insulator-graphene heterostructures

    Science.gov (United States)

    Rodriguez-Vega, M.; Schwiete, G.; Sinova, J.; Rossi, E.

    2017-12-01

    The control of a ferromagnet's magnetization via only electric currents requires the efficient generation of current-driven spin torques. In magnetic structures based on topological insulators (TIs) current-induced spin-orbit torques can be generated. Here we show that the addition of graphene, or bilayer graphene, to a TI-based magnetic structure greatly enhances the current-induced spin-density accumulation and significantly reduces the amount of power dissipated. We find that this enhancement can be as high as a factor of 100, giving rise to a giant Edelstein effect. Such a large enhancement is due to the high mobility of graphene (bilayer graphene) and to the fact that the graphene (bilayer graphene) sheet very effectively screens charge impurities, the dominant source of disorder in topological insulators. Our results show that the integration of graphene in spintronics devices can greatly enhance their performance and functionalities.

  10. Quantum magnetotransport properties of topological insulators under strain

    KAUST Repository

    Tahir, M.

    2012-08-15

    We present a detailed theoretical investigation of the quantum magnetotransport properties of topological insulators under strain. We consider an external magnetic field perpendicular to the surface of the topological insulator in the presence of strain induced by the substrate. The strain effects mix the lower and upper surface states of neighboring Landau levels into two unequally spaced energy branches. Analytical expressions are derived for the collisional conductivity for elastic impurity scattering in the first Born approximation. We also calculate the Hall conductivity using the Kubo formalism. Evidence for the beating of Shubnikov–de Haas oscillations is found from the temperature and magnetic field dependence of the collisional and Hall conductivities. In the regime of a strong magnetic field, the beating pattern is replaced by a splitting of the magnetoresistance peaks due to finite strain energy. These results are in excellent agreement with recent HgTe transport experiments.

  11. Identifying Cancer Subtypes from miRNA-TF-mRNA Regulatory Networks and Expression Data.

    Directory of Open Access Journals (Sweden)

    Taosheng Xu

    Full Text Available Identifying cancer subtypes is an important component of the personalised medicine framework. An increasing number of computational methods have been developed to identify cancer subtypes. However, existing methods rarely use information from gene regulatory networks to facilitate the subtype identification. It is widely accepted that gene regulatory networks play crucial roles in understanding the mechanisms of diseases. Different cancer subtypes are likely caused by different regulatory mechanisms. Therefore, there are great opportunities for developing methods that can utilise network information in identifying cancer subtypes.In this paper, we propose a method, weighted similarity network fusion (WSNF, to utilise the information in the complex miRNA-TF-mRNA regulatory network in identifying cancer subtypes. We firstly build the regulatory network where the nodes represent the features, i.e. the microRNAs (miRNAs, transcription factors (TFs and messenger RNAs (mRNAs and the edges indicate the interactions between the features. The interactions are retrieved from various interatomic databases. We then use the network information and the expression data of the miRNAs, TFs and mRNAs to calculate the weight of the features, representing the level of importance of the features. The feature weight is then integrated into a network fusion approach to cluster the samples (patients and thus to identify cancer subtypes. We applied our method to the TCGA breast invasive carcinoma (BRCA and glioblastoma multiforme (GBM datasets. The experimental results show that WSNF performs better than the other commonly used computational methods, and the information from miRNA-TF-mRNA regulatory network contributes to the performance improvement. The WSNF method successfully identified five breast cancer subtypes and three GBM subtypes which show significantly different survival patterns. We observed that the expression patterns of the features in some miRNA-TF

  12. Chiral topological excitons in a Chern band insulator

    Science.gov (United States)

    Chen, Ke; Shindou, Ryuichi

    2017-10-01

    A family of semiconductors called Chern band insulators are shown to host exciton bands with nonzero topological Chern integers and chiral exciton edge modes. Using a prototypical two-band Chern insulator model, we calculate a cross-correlation function to obtain the exciton bands and their Chern integers. The lowest exciton band acquires Chern integers such as ±1 and ±2 in the electronic Chern insulator phase. The nontrivial topology can be experimentally observed both by a nonlocal optoelectronic response of exciton edge modes and by a phase shift in the cross-correlation response due to the bulk mode. Our result suggests that magnetically doped HgTe, InAs/GaSb quantum wells, and (Bi,Sb)2Te3 thin films are promising candidates for a platform of topological excitonics.

  13. Unconventional quantum Hall effect in Floquet topological insulators

    KAUST Repository

    Tahir, M.

    2016-07-27

    We study an unconventional quantum Hall effect for the surface states of ultrathin Floquet topological insulators in a perpendicular magnetic field. The resulting band structure is modified by photon dressing and the topological property is governed by the low-energy dynamics of a single surface. An exchange of symmetric and antisymmetric surface states occurs by reversing the lights polarization. We find a novel quantum Hall state in which the zeroth Landau level undergoes a phase transition from a trivial insulator state, with Hall conductivity αyx = 0 at zero Fermi energy, to a Hall insulator state with αyx = e2/2h. These findings open new possibilities for experimentally realizing nontrivial quantum states and unusual quantum Hall plateaus at (±1/2,±3/2,±5/2, ...)e2/h. © 2016 IOP Publishing Ltd Printed in the UK.

  14. Disorder enabled band structure engineering of a topological insulator surface

    International Nuclear Information System (INIS)

    Xu, Yishuai; Chiu, Janet; Miao, Lin; He, Haowei

    2017-01-01

    Three-dimensional topological insulators are bulk insulators with Z 2 topological electronic order that gives rise to conducting light-like surface states. These surface electrons are exceptionally resistant to localization by non-magnetic disorder, and have been adopted as the basis for a wide range of proposals to achieve new quasiparticle species and device functionality. Recent studies have yielded a surprise by showing that in spite of resisting localization, topological insulator surface electrons can be reshaped by defects into distinctive resonance states. Here we use numerical simulations and scanning tunnelling microscopy data to show that these resonance states have significance well beyond the localized regime usually associated with impurity bands. Lastly, at native densities in the model Bi 2 X 3 (X=Bi, Te) compounds, defect resonance states are predicted to generate a new quantum basis for an emergent electron gas that supports diffusive electrical transport.

  15. Application of [HMim][NTf2], [HMim][TfO] and [BMim][TfO] ionic liquids on the extraction of toluene from alkanes: Effect of the anion and the alkyl chain length of the cation on the LLE

    International Nuclear Information System (INIS)

    Corderí, Sandra; González, Emilio J.; Calvar, Noelia; Domínguez, Ángeles

    2012-01-01

    Highlights: ► Several ionic liquids were studied as solvent to extract toluene from heptane and cyclohexane. ► (Liquid + liquid) equilibrium data were measured at 298.15 K and atmospheric pressure. ► Selectivity and solute distribution ratio were calculated and compared with those found in literature for sulfolane. ► Experimental data were correlated using NRTL and UNIQUAC thermodynamic models. - Abstract: In this paper, the separation of toluene from the aliphatic hydrocarbons heptane and cyclohexane employing the ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [HMim][NTf 2 ], 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, [HMim][TfO] and 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [BMim][TfO], as solvents was studied and discussed. Liquid–liquid equilibrium data for the ternary systems {heptane, or cyclohexane + toluene + [HMim][NTf 2 ], or [HMim][TfO], or [BMim][TfO]} and {heptane + cyclohexane + [HMim][NTf 2 ], or [HMim][TfO], or [BMim][TfO]} were measured at T = 298.15 K and atmospheric pressure. The degree of consistency of the tie-lines was tested using the Othmer–Tobias equation. The solute distribution ratio and selectivity, derived from the experimental tie-lines, were used to determine if these ionic liquids can be used as potential solvents on the extraction of toluene from aliphatic hydrocarbons; a comparison with literature data where sulfolane is used as solvent was also included. Finally, the experimental data were correlated with the NRTL and UNIQUAC thermodynamic models.

  16. Improving the computation efficiency of COBRA-TF for LWR safety analysis of large problems

    International Nuclear Information System (INIS)

    Cuervo, D.; Avramova, M. N.; Ivanov, K. N.

    2004-01-01

    A matrix solver is implemented in COBRA-TF in order to improve the computation efficiency of both numerical solution methods existing in the code, the Gauss elimination and the Gauss-Seidel iterative technique. Both methods are used to solve the system of pressure linear equations and relay on the solution of large sparse matrices. The introduced solver accelerates the solution of these matrices in cases of large number of cells. The execution time is reduced in half as compared to the execution time without using matrix solver for the cases with large matrices. The achieved improvement and the planned future work in this direction are important for performing efficient LWR safety analyses of large problems. (authors)

  17. Thermal-hydraulic analysis of LTS cables for the DEMO TF coil using simplified models

    Directory of Open Access Journals (Sweden)

    Lewandowska Monika

    2017-03-01

    Full Text Available The conceptual design activities for the DEMOnstration reactor (DEMO – the prototype fusion power plant – are conducted in Europe by the EUROfusion Consortium. In 2015, three design concepts of the DEMO toroidal field (TF coil were proposed by Swiss Plasma Center (EPFL-SPC, PSI Villigen, Italian National Agency for New Technologies (ENEA Frascati, and Atomic Energy and Alternative Energies Commission (CEA Cadarache. The proposed conductor designs were subjected to complete mechanical, electromagnetic, and thermal-hydraulic analyses. The present study is focused on the thermal-hydraulic analysis of the candidate conductor designs using simplified models. It includes (a hydraulic analysis, (b heat removal analysis, and (c assessment of the maximum temperature and the maximum pressure in each conductor during quench. The performed analysis, aimed at verification whether the proposed design concepts fulfil the established acceptance criteria, provides the information for further improvements of the coil and conductors design.

  18. Quickly Planning TF/TA2 Trajectory by Artificial Immune Algorithm

    Directory of Open Access Journals (Sweden)

    LIU Lifeng

    2015-04-01

    Full Text Available Flight path planning by artificial immune algorithm approach met the requirements of aircraft's flyability and operation is proposed for the problem of single and double TF/TA2 flight path planning. Punishment function (affinity function with comprehensive 3D threat information is designed. A comprehensive threat model is formed including dynamic and static threats and no-fly-zone. Accordingly, single and dual flight paths are planned by AIA, which have been compared with the paths by GA. The results show that, GA's planned a quick and longer path compared under simple threat environment; in complex environments, GA has high failure rate (greater than 95% for single aircraft, but it is failed for double aircrafts. For the single and double aircrafts, AIA can provides one optimal and more candidate optimal flight paths.

  19. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  20. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  1. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  2. 16 CFR 460.18 - Insulation ads.

    Science.gov (United States)

    2010-01-01

    ... Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES LABELING AND ADVERTISING OF HOME INSULATION § 460.18 Insulation ads. (a) If your ad gives an R-value, you must give the type of insulation and... your ad gives a price, you must give the type of insulation, the R-value at a specific thickness, the...

  3. Thermal/acoustical insulation foam

    Science.gov (United States)

    Lin, R. Y.; Struzik, E. A.

    1976-01-01

    Lightweight low-density substance can be used as fire resistant insulation in aircraft. Material density can be controlled over range from 0.6-1.2 pounds per cubic foot and has good thermal and acoustic properties.

  4. Evaluation of thermal insulation materials

    Science.gov (United States)

    Wilbers, O. J.; Conti, J. C.; Mcgee, J. V.; Mcpherson, J. I.

    1973-01-01

    Data was obtained on silicone-bonded fiberglass, isocyanurate foam, and two dozen other insulators. Materials were selected to withstand heat sterilization, outer space, and the Martian atmosphere. Significant environmental parameters were vibration, landing shock, and launch venting.

  5. Metal-insulator-semiconductor photodetectors.

    Science.gov (United States)

    Lin, Chu-Hsuan; Liu, Chee Wee

    2010-01-01

    The major radiation of the sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  6. Metal-Insulator-Semiconductor Photodetectors

    Directory of Open Access Journals (Sweden)

    Chu-Hsuan Lin

    2010-09-01

    Full Text Available The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  7. Measure Guideline: Basement Insulation Basics

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, R.; Mantha, P.; Puttagunta, S.

    2012-10-01

    This guideline is intended to describe good practices for insulating basements in new and existing homes, and is intended to be a practical resources for building contractors, designers, and also to homeowners.

  8. Redesigning pH optimum of Geobacillus sp. TF16 endoxylanase through in silico designed DNA swapping strategy.

    Science.gov (United States)

    Uzuner, Ugur; Canakci, Sabriye; Bektas, Kadriye Inan; Sapmaz, Merve Tuncel; Belduz, Ali Osman

    2017-06-01

    Thermoalkaliphilic xylanases are highly desired and of great importance due to their vast potential in paper pulp and bleaching processes. Here, we report rapid, cost-effective, and result-oriented combinatorial potential of in silico DNA swapping strategy to engineer the pH optimum of industrially crucial enzymes, particularly engineering of Geobacillus sp. TF16 endoxylanase for alkaline environments. The 3D structures of Geobacillus sp. TF16 and donor Bacillus halodurans C-125 endoxylanases were firstly predicted, analyzed, and compared for their similarities before any in silico design of mutants. Reasonably, to improve its alkaline pH tolerance, the corresponding regions in Geobacillus sp.TF16 endoxylanase were further engineered by swapping with negatively-charged amino acid-rich regions from B. halodurans C-125 endoxylanase. Through only two of four in silico-designed mutants, the optimum pH of GeoTF16 endoxylanase was improved from 8.5 to 10.0. Moreover, as compared to GeoTF16 parental enzyme, both GeoInt3 and GeoInt4 mutants revealed (i) enhanced biobleaching performance, (ii) improved adaptability to alkaline conditions, and (iii) better activity for broader pH range. Unlike GeoTF16 losing activity at pH 11.0 completely, GeoInt4 retained 60% and 40% of its activity at pH 11.0 and 12.0, respectively. Thus, GeoInt4 stands out as a more competent biocatalyst that is suitable for alkaline environments of diverse industrial applications. The current study represents an efficient protein engineering strategy to adapt industrial catalysts to diverse processing conditions. Further comprehensive and fine-tuned research efforts may result in biotechnologically more promising outcomes. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  9. Spin-torque generation in topological insulator based heterostructures

    KAUST Repository

    Fischer, Mark H.

    2016-03-11

    Heterostructures utilizing topological insulators exhibit a remarkable spin-torque efficiency. However, the exact origin of the strong torque, in particular whether it stems from the spin-momentum locking of the topological surface states or rather from spin-Hall physics of the topological-insulator bulk, remains unclear. Here, we explore a mechanism of spin-torque generation purely based on the topological surface states. We consider topological-insulator-based bilayers involving ferromagnetic metal (TI/FM) and magnetically doped topological insulators (TI/mdTI), respectively. By ascribing the key theoretical differences between the two setups to location and number of active surface states, we describe both setups within the same framework of spin diffusion of the nonequilibrium spin density of the topological surface states. For the TI/FM bilayer, we find large spin-torque efficiencies of roughly equal magnitude for both in-plane and out-of-plane spin torques. For the TI/mdTI bilayer, we elucidate the dominance of the spin-transfer-like torque. However, we cannot explain the orders of magnitude enhancement reported. Nevertheless, our model gives an intuitive picture of spin-torque generation in topological-insulator-based bilayers and provides theoretical constraints on spin-torque generation due to topological surface states.

  10. Spin-transfer torque generated by a topological insulator

    KAUST Repository

    Mellnik, A. R.

    2014-07-23

    Magnetic devices are a leading contender for the implementation of memory and logic technologies that are non-volatile, that can scale to high density and high speed, and that do not wear out. However, widespread application of magnetic memory and logic devices will require the development of efficient mechanisms for reorienting their magnetization using the least possible current and power. There has been considerable recent progress in this effort; in particular, it has been discovered that spin-orbit interactions in heavy-metal/ferromagnet bilayers can produce strong current-driven torques on the magnetic layer, via the spin Hall effect in the heavy metal or the Rashba-Edelstein effect in the ferromagnet. In the search for materials to provide even more efficient spin-orbit-induced torques, some proposals have suggested topological insulators, which possess a surface state in which the effects of spin-orbit coupling are maximal in the sense that an electron\\' s spin orientation is fixed relative to its propagation direction. Here we report experiments showing that charge current flowing in-plane in a thin film of the topological insulator bismuth selenide (Bi2Se3) at room temperature can indeed exert a strong spin-transfer torque on an adjacent ferromagnetic permalloy (Ni81Fe19) thin film, with a direction consistent with that expected from the topological surface state. We find that the strength of the torque per unit charge current density in Bi 2Se3 is greater than for any source of spin-transfer torque measured so far, even for non-ideal topological insulator films in which the surface states coexist with bulk conduction. Our data suggest that topological insulators could enable very efficient electrical manipulation of magnetic materials at room temperature, for memory and logic applications. © 2014 Macmillan Publishers Limited. All rights reserved.

  11. DEALS: a maintainable superconducting magnet system for tokamak fusion reactors

    International Nuclear Information System (INIS)

    Hseih, S.Y.; Danby, G.; Powell, J.R.

    1979-01-01

    The feasibility of demountable superconducting magnet systems has been examined in a design study of a DEALS [Demountable Externally Anchored Low Stress] TF magnet for an HFITR [High Field Ignition Test Reactor] Tokamak device. All parts of the system appear feasible, including the demountable superconducting joints. Measurements on small scale prototype joints indicate that movable pressure contact joints exhibit acceptable electrical, mechanical, and cryogenic performance. Such joints permit a relatively simple support structure and are readily demountable. Assembly and disassembly sequences are described whereby any failed portion of the magnet, or any part of the reactor inside the TF coils can be removed and replaced if necessary

  12. Room temperature giant and linear magnetoresistance in topological insulator Bi2Te3 nanosheets.

    Science.gov (United States)

    Wang, Xiaolin; Du, Yi; Dou, Shixue; Zhang, Chao

    2012-06-29

    Topological insulators, a new class of condensed matter having bulk insulating states and gapless metallic surface states, have demonstrated fascinating quantum effects. However, the potential practical applications of the topological insulators are still under exploration worldwide. We demonstrate that nanosheets of a Bi(2)Te(3) topological insulator several quintuple layers thick display giant and linear magnetoresistance. The giant and linear magnetoresistance achieved is as high as over 600% at room temperature, with a trend towards further increase at higher temperatures, as well as being weakly temperature-dependent and linear with the field, without any sign of saturation at measured fields up to 13 T. Furthermore, we observed a magnetic field induced gap below 10 K. The observation of giant and linear magnetoresistance paves the way for 3D topological insulators to be useful for practical applications in magnetoelectronic sensors such as disk reading heads, mechatronics, and other multifunctional electromagnetic applications.

  13. Magnetohydrodynamic Effects on Insulating Bubbles and Inclusions in the Continuous Casting of Steel

    NARCIS (Netherlands)

    J.W. Haverkort (Willem); T.W.J. Peeters

    2010-01-01

    textabstractThe magnetohydrodynamic effects associated with a magnetic field perpendicular to the movement of insulating inclusions or bubbles in a conducting liquid are investigated in this article. An increase in drag coefficient as a result of the presence of a magnetic field is argued to have a

  14. Optical properties of topological insulator nanoparticles

    Science.gov (United States)

    Siroki, Gleb; Lee, Derek; Haynes, Peter; Giannini, Vincenzo

    Topological insulators are materials that have metallic surface states protected by time-reversal symmetry. Such states are delocalised over the surface and are immune to non-magnetic defects and impurities. Building on previous work we have studied the interaction of light with topological insulator nanoparticles. Our main finding is that the occupied surface states can lead to charge density oscillations akin to plasmons in metallic nanoparticles. Furthermore, these oscillations can couple to phonons forming a previously unreported excitation. Because the states are localised at the surface a small number of them is enough to change the absorption spectrum of a particle containing many thousands of atoms. We are going to show how the effect can be adjusted by varying the particle's size and shape. Furthermore, we will discuss the robustness of the effect in the presence of disorder. In conclusion, topological nanoparticles can be used as a highly-tunable building block to create a metamaterial operating in THz range. This may be interesting for plasmonics and metamaterials communities as well as researchers working on cavity electrodynamics and quantum information. G.S. was supported through a studentship in the Centre for Doctoral Training on Theory and Simulation of Materials at Imperial College London funded by EPSRC Grant No. EP/L015579/1. V.G. acknowledges support of Leverhulme Trust.

  15. Testing electrical insulation of LCT coils and instrumentation

    International Nuclear Information System (INIS)

    Luton, J.N.; Ulbricht, A.R.; Ellis, J.F.; Shen, S.S.; Wilson, C.T.; Okuno, K.; Siewerdt, L.O.; Zahn, G.R.; Zichy, J.A.

    1986-09-01

    Three of the superconducting test coils in the Large Coil Task (LCT) use conductors cooled internally by forced flow of helium. In the other three coils, the conductors are cooled externally by a bath of helium. The coils and facility are designed for rapid discharges (dumps) at voltages up to 2.5 kV, depending on coil design. Many coil sensors are connected electrically to the conductors. These sensor leads and signal conditioning equipment also experience high voltage. High-potential tests of ground insulation were performed on all components of the International Fusion Superconducting Magnet Test Facility (IFSMTF). Coil insulation was also tested by ring-down tests that produced voltage distributions within the coils like those occurring during rapid discharge. Methods were developed to localize problem areas and to eliminate them. The effect on breakdown voltage near the Paschen minimum of magnetic fields up to 2 T was investigated

  16. Modulation of pure spin currents with a ferromagnetic insulator

    Science.gov (United States)

    Villamor, Estitxu; Isasa, Miren; Vélez, Saül; Bedoya-Pinto, Amilcar; Vavassori, Paolo; Hueso, Luis E.; Bergeret, F. Sebastián; Casanova, Fèlix

    2015-01-01

    We propose and demonstrate spin manipulation by magnetically controlled modulation of pure spin currents in cobalt/copper lateral spin valves, fabricated on top of the magnetic insulator Y3F e5O12 (YIG). The direction of the YIG magnetization can be controlled by a small magnetic field. We observe a clear modulation of the nonlocal resistance as a function of the orientation of the YIG magnetization with respect to the polarization of the spin current. Such a modulation can only be explained by assuming a finite spin-mixing conductance at the Cu/YIG interface, as it follows from the solution of the spin-diffusion equation. These results open a path towards the development of spin logics.

  17. A Parametric Study of Thermal Performance of an Exterior Wall Insulated with Vacuum Insulation Panels

    OpenAIRE

    Ciobanu, Adrian-Alexandru; Iacob, Adrian

    2013-01-01

    The requirements regarding thermal insulation of the new buildings and thermal rehabilitation of the existing buildings tend to reach a threshold of insulation which allows to fulfill the necessary requirements for a low-energy building. To achieve this level of thermal insulation involves using either thick layers of conventional insulation (polystyrene, mineral wool, etc.) or high thermal performance materials. Vacuum insulation panels are high performance thermal insulation characteri...

  18. Impact of sodium butyrate and mild hypothermia on metabolic and physiological behaviour of CHO TF 70R cells

    Directory of Open Access Journals (Sweden)

    Veronica Avello

    2017-05-01

    Conclusions: The combination of NaBu addition and mild hypothermic condition causes an impact on physiological and metabolic state of CHO TF 70R cells, decreasing cell growth rate and improving glucose consumption efficiency. These results therefore provide a promising strategy to increase specific productivity of rh-tPA.

  19. Inhibitory activity of Lactobacillus plantarum TF711 against Clostridium sporogenes when used as adjunct culture in cheese manufacture.

    Science.gov (United States)

    González, Lorena; Zárate, Victoria

    2015-05-01

    Bacteriocins produced by lactic acid bacteria are of great interest to the food-processing industry as natural preservatives. This work aimed to investigate the efficacy of bacteriocin-producing Lactobacillus plantarum TF711, isolated from artisanal Tenerife cheese, in controlling Clostridium sporogenes during cheese ripening. Cheeses were made from pasteurised milk artificially contaminated with 10(4) spores m/l C. sporogenes. Experimental cheeses were manufactured with Lb. plantarum TF711 added at 1% as adjunct to commercial starter culture. Cheeses made under the same conditions but without Lb. plantarum TF711 served as controls. Evolution of microbiological parameters, pH and NaCl content, as well as bacteriocin production was studied throughout 45 d of ripening. Addition of Lb. plantarum TF711 did not bring about any significant change in starter culture counts, NaCl content and pH, compared with control cheese. In contrast, clostridial spore count in experimental cheeses were significantly lower than in control cheeses from 7 d onwards, reaching a maximum reduction of 2·2 log units on day 21. Inhibition of clostridia found in experimental cheeses was mainly attributed to plantaricin activity, which in fact was recovered from these cheeses.

  20. MAGNETIC PROPERTIES OF THE SPINEL COMPOUND Cu1.30Cr1.30Zr0.70Se4

    Directory of Open Access Journals (Sweden)

    K BELAKROUM

    2009-12-01

    antiferromagnetic interactions due to the substitution of magnetic Cr for Zr atom, on the B sites forming a network of linked tetrahedral. The magnetization in field-cooled (FC and zero-fieldcooled (ZFC are observed with irreversibility in T≤ Tf, the overage Curie temperature, the effective magnetic moment and the temperature range, for which magnetic susceptibility can be regarded as linear are given.

  1. Effects of pressure on doped Kondo insulators

    International Nuclear Information System (INIS)

    Lee, Chengchung; Xu, Wang

    1999-08-01

    The effects of pressure on the doped Kondo insulators (KI) are studied in the framework of the slave-boson mean-field theory under the coherent potential approximation (CPA). A unified picture for both electron-type KI and hole-type KI is presented. The density of states of the f-electrons under the applied pressures and its variation with the concentration of the Kondo holes are calculated self-consistently. The specific heat coefficient, the zero-temperature magnetic susceptibility as well as the low temperature electric resistivity of the doped KI under various pressures are obtained. The two contrasting pressure-dependent effects observed in the doped KI systems can be naturally explained within a microscopic model. (author)

  2. Lieb polariton topological insulators

    Science.gov (United States)

    Li, Chunyan; Ye, Fangwei; Chen, Xianfeng; Kartashov, Yaroslav V.; Ferrando, Albert; Torner, Lluis; Skryabin, Dmitry V.

    2018-02-01

    We predict that the interplay between the spin-orbit coupling, stemming from the transverse electric-transverse magnetic energy splitting, and the Zeeman effect in semiconductor microcavities supporting exciton-polariton quasiparticles, results in the appearance of unidirectional linear topological edge states when the top microcavity mirror is patterned to form a truncated dislocated Lieb lattice of cylindrical pillars. Periodic nonlinear edge states are found to emerge from the linear ones. They are strongly localized across the interface and they are remarkably robust in comparison to their counterparts in honeycomb lattices. Such robustness makes possible the existence of nested unidirectional dark solitons that move steadily along the lattice edge.

  3. Mott-to-Goodenough insulator-insulator transition in LiVO2

    Science.gov (United States)

    Subedi, Alaska

    2017-06-01

    I critically examine Goodenough's explanation for the experimentally observed phase transition in LiVO2 using microscopic calculations based on density functional and dynamical mean field theories. The high-temperature rhombohedral phase exhibits both magnetic and dynamical instabilities. Allowing a magnetic solution for the rhombohedral structure does not open an insulating gap, and an explicit treatment of the on-site Coulomb U interaction is needed to stabilize an insulating rhombohedral phase. The non-spin-polarized phonon dispersions of the rhombohedral phase show two unstable phonon modes at the wave vector (1/3 ,-1/3 ,0 ) that corresponds to the experimentally observed trimer forming instability. A full relaxation of the supercell corresponding to this instability yields a nonmagnetic state containing V3 trimers. These results are consistent with Goodenough's suggestion that the high-temperature phase is in the localized-electron regime and the transition to the low-temperature phase in the itinerant-electron regime is driven by V-V covalency.

  4. Multipurpose Thermal Insulation Test Apparatus

    Science.gov (United States)

    Fesmire, James E. (Inventor); Augustynowicz, Stanislaw D. (Inventor)

    2002-01-01

    A multi-purpose thermal insulation test apparatus is used for testing insulation materials, or other components. The test apparatus is a fluid boil-off calorimeter system for calibrated measurement of the apparent thermal conductivity (k-value) of a specimen material at a fixed vacuum level. The apparatus includes an inner vessel for receiving a fluid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including the inner vessel and thermal guards, is suspended from the top of the vacuum chamber. Handling tools attach to the cold mass assembly for convenient manipulation of the assembly and for the installation or wrapping of insulation test materials. Liquid nitrogen is typically supplied to the inner vessel using a fill tube with funnel. A single port through the top of the vacuum chamber facilitates both filling and venting. Aerogel composite stacks with reflective films are fastened to the top and the bottom of the inner vessel as thermal guards. The comparative k-value of the insulation material is determined by measuring the boil-off flow rate of gas, the temperature differential across the insulation thickness, and the dimensions (length and diameters) of the test specimen.

  5. Passive Collecting of Solar Radiation Energy using Transparent Thermal Insulators, Energetic Efficiency of Transparent Thermal Insulators

    Directory of Open Access Journals (Sweden)

    Smajo Sulejmanovic

    2014-11-01

    Full Text Available This paper explains passive collection of solar radiation energy using transparent thermal insulators. Transparent thermal insulators are transparent for sunlight, at the same time those are very good thermal insulators. Transparent thermal insulators can be placed instead of standard conventional thermal insulators and additionally transparent insulators can capture solar radiation, transform it into heat and save heat just as standard insulators. Using transparent insulators would lead to reduce in usage of fossil fuels and would help protection of an environment and reduce effects of global warming, etc.

  6. Evidence for ferromagnetic coupling at the doped topological insulator/ferrimagnetic insulator interface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenqing [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); York-Nanjing Joint Centre for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Physics Department, Hong Kong University (Hong Kong); He, Liang; Zhang, Rong, E-mail: yongbing.xu@york.ac.uk, E-mail: rzhang@nju.edu.cn, E-mail: wang@seas.ucla.edu [York-Nanjing Joint Centre for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhou, Yan [York-Nanjing Joint Centre for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China); Physics Department, Hong Kong University (Hong Kong); Murata, Koichi; Wang, Kang L., E-mail: yongbing.xu@york.ac.uk, E-mail: rzhang@nju.edu.cn, E-mail: wang@seas.ucla.edu [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Onbasli, Mehmet C.; Ross, Caroline A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Jiang, Ying; Wang, Yong [Centre of Electron Microscopy, State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027 (China); Xu, Yongbing, E-mail: yongbing.xu@york.ac.uk, E-mail: rzhang@nju.edu.cn, E-mail: wang@seas.ucla.edu [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); York-Nanjing Joint Centre for Spintronics and Nano Engineering (YNJC), School of Electronics Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2016-05-15

    One of the major obstacles of the magnetic topological insulators (TIs) impeding their practical use is the low Curie temperature (T{sub c}). Very recently, we have demonstrated the enhancement of the magnetic ordering in Cr-doped Bi{sub 2}Se{sub 3} by means of proximity to the high-T{sub c} ferrimagnetic insulator (FMI) Y{sub 3}Fe{sub 5}O{sub 12} and found a large and rapidly decreasing penetration depth of the proximity effect, suggestive of a different carrier propagation process near the TI surface. Here we further present a study of the interfacial magnetic interaction of this TI/FMI heterostrucutre. The synchrotron-based X-ray magnetic circular dichroism (XMCD) technique was used to probe the nature of the exchange coupling of the Bi{sub 2−x}Cr{sub x}Se{sub 3}/Y{sub 3}Fe{sub 5}O{sub 12} interface. We found that the Bi{sub 2−x}Cr{sub x}Se{sub 3} grown on Y{sub 3}Fe{sub 5}O{sub 12}(111) predominately contains Cr{sup 3+} cations, and the spin direction of the Cr{sup 3+} is aligned parallel to that of tetrahedral Fe{sup 3+} of the YIG, revealing a ferromagnetic exchange coupling between the Bi{sub 2−x}Cr{sub x}Se{sub 3} and the Y{sub 3}Fe{sub 5}O{sub 12}.

  7. INFORMATION RETRIEVAL OF TEXT DOCUMENT WITH WEIGHTING TF-IDF AND LCS

    Directory of Open Access Journals (Sweden)

    Munjiah Nur Saadah

    2013-10-01

    Full Text Available Information retrieval of text document requires a method that is able to restore a number of documents that have high relevance according to the user's request. One important step in the process is a text representation of the weighting process. The use of LCS in Tf-Idf weighting adjustments considers the appearance of the same order of words between the query and the text in the document. There is a very long document but irrelevant cause weight produced is not able to represent the value relevance of documents. This research proposes the use of LCS which gives weight to the word order by considering long documents related to the average length of documents in the corpus. This method is able to return a text document effectively. Additional features of word order by normalizing the ratio of the overall length of the document to the documents in the corpus generate values of precision and recall as well as the method of Tasi et al.

  8. Starting the production of the CEA JT-60SA TF coils at Alstom

    Energy Technology Data Exchange (ETDEWEB)

    Decool, P., E-mail: patrick.decool@cea.fr [CEA, IRFM, F-13108 St-Paul-Lez-Durance Cedex (France); Cloez, H.; Gros, G.; Jiolat, G.; Marechal, J.L.; Nicollet, S.; Torre, A.; Verger, J.M. [CEA, IRFM, F-13108 St-Paul-Lez-Durance Cedex (France); Nusbaum, M.; Billotte, G.; Crepel, B.; Bourquard, A.; Schweitzer, M. [Alstom Power Systems STTG Magnets, 90018 Belfort (France); Davis, S.; Phillips, G. [Fusion for Energy, Boltzmannstr 2, 85748 Garching (Germany)

    2015-10-15

    Highlights: • We describe the status of the JT-60SA TF coils manufacture at Alstom. • The manufacturing workflow and related tooling are described. • Completion of qualification activities has allowed to start the coils production. • Production of the first winding up to its impregnation is described. • Winding of following coils is started. - Abstract: Within the framework of the Broader Approach, the French voluntary contributor represented by CEA awarded a contract for the production of 9 toroidal field coils for the JT-60SA project to Alstom, Belfort, France in mid-2011. A first preparatory phase was led to establish the team, produce the manufacture drawings, define the manufacturing process, procure the required tooling and prepare the quality documentation. In parallel, a qualification phase on the critical major processes has proved Alstom's ability to master the processes and reach the requirements. After reviewing of the qualification results and modification of the processes and tooling to overcome the encountered difficulties, a Production Readiness Review has authorized Alstom to start the production winding. A prototype double pancake was wound as the first of series. In addition to complying with the pancake width all around the D shape, the straightness of the centreline in the critical straight leg part was correct. The production of the successive double pancakes to constitute the first winding pack was then completed and the joints and terminals were manufactured. The paper describes the completion of the last qualifications and the status of the winding production.

  9. Characterization of AFLAV, a Tf1/Sushi retrotransposon from Aspergillus flavus.

    Science.gov (United States)

    Hua, Sui-Sheng T; Tarun, Alice S; Pandey, Sonal N; Chang, Leo; Chang, Perng-Kuang

    2007-02-01

    The plasmid, pAF28, a genomic clone from Aspergillus flavus NRRL 6541, has been used as a hybridization probe to fingerprint A. flavus strains isolated in corn and peanut fields. The insert of pAF28 contains a 4.5 kb region which encodes a truncated retrotransposon (AfRTL-1). In search for a full-length and intact copy of retrotransposon, we exploited a novel PCR cloning strategy by amplifying a 3.4 kb region from the genomic DNA of A. flavus NRRL 6541. The fragment was cloned into pCR 4-TOPO. Sequence analysis confirmed that this region encoded putative domains of partial reverse transcriptase, RNase H, and integrase of the predicted retrotransposon. The two flanking long terminal repeats (LTRs) and the sequence between them comprise a putative full-length LTR retrotransposon of 7799 bp in length. This intact retrotransposon sequence is named AFLAV (A. flavus Retrotransposon). The order of the predicted catalytic domains in the polyprotein (Pol) placed AFLAV in the Tf1/sushi subgroup of the Ty3/gypsy retrotransposon family. Primers derived from AFLAV sequence were used to screen this retrotransposon in other strains of A. flavus. More than fifty strains of A. flavus isolated from different geological origins were surveyed and the results show that many strains have extensive deletions in the regions encoding the capsid (Gag) and Pol.

  10. On the peculiarities of galvanomagnetic effects in high magnetic fields in twisting bicrystals of the 3D topological insulator Bi{sub 1–x}Sb{sub x} (0.07 ≤ x ≤ 0.2)

    Energy Technology Data Exchange (ETDEWEB)

    Muntyanu, F. M., E-mail: muntean-teodor@yahoo.com [Academy of Sciences of Moldova, Institute of Electronic Engineering and Industrial Technologies (Moldova, Republic of); Gheorghitsa, E. I. [Technical University of Moldova (Moldova, Republic of); Gilewski, A. [International Laboratory of High Magnetic Fields and Low Temperatures (Poland); Chistol, V. [Tiraspol State University (Moldova, Republic of); Bejan, V. [Technical University of Moldova (Moldova, Republic of); Munteanu, V. [Academy of Sciences of Moldova, Institute of Electronic Engineering and Industrial Technologies (Moldova, Republic of)

    2017-04-15

    Galvanomagnetic effects in twisting bicrystals of Bi{sub 1–x}Sb{sub x} alloys (0.07 ≤ x ≤ 0.2) at low temperatures and in magnetic fields up to 40 T are studied. It is found that, at small crystallite misorientation angles, the semiconductor–semimetal transition is induced in the central layer (~60-nm-thick) and two adjacent layers (each ~20-nm-thick) of the interface at different values of ultraquantum magnetic field. Bicrystals with large misorientation angles, being located in strong magnetic fields, exhibit quantum oscillations of the magnetoresistance and the Hall effect, thus indicating that the density of states is higher and charge carriers are heavier in the adjacent layers of the interfaces than in the crystallites. Our results show also that twisting bicrystals contain regions with different densities of quantum electronic states, which are determined by the crystallite misorientation angle and magnetic-field strength.

  11. Floquet topological insulators for sound

    Science.gov (United States)

    Fleury, Romain; Khanikaev, Alexander B.; Alù, Andrea

    2016-06-01

    The unique conduction properties of condensed matter systems with topological order have recently inspired a quest for the similar effects in classical wave phenomena. Acoustic topological insulators, in particular, hold the promise to revolutionize our ability to control sound, allowing for large isolation in the bulk and broadband one-way transport along their edges, with topological immunity against structural defects and disorder. So far, these fascinating properties have been obtained relying on moving media, which may introduce noise and absorption losses, hindering the practical potential of topological acoustics. Here we overcome these limitations by modulating in time the acoustic properties of a lattice of resonators, introducing the concept of acoustic Floquet topological insulators. We show that acoustic waves provide a fertile ground to apply the anomalous physics of Floquet topological insulators, and demonstrate their relevance for a wide range of acoustic applications, including broadband acoustic isolation and topologically protected, nonreciprocal acoustic emitters.

  12. Angle-resolved photoemission spectroscopy of (Ca, Na) sub 2 CuO sub 2 Cl sub 2 crystals: Fingerprints of a magnetic insulator in a heavily underdoped superconductor

    CERN Document Server

    Kohsaka, Y; Ronning, F

    2003-01-01

    Electric evolution from an antiferromagnet to a high-T sub c superconductor is revealed by angle-resolved photoemission experiments on tetragonal Ca sub 1 sub . sub 9 Na sub 0 sub . sub 1 CuO sub 2 Cl sub 2 single crystals, which were successfully grown for the first time under high pressures. In this underdoped superconductor, we found clear fingerprints of the parent insulator: a shadow band and a large pseudogap. These observations are most likely described by a 'chemical potential shift', which contrasts clearly with the prevailing wisdom of the pinned chemical potential' learned from the prototype La sub 2 sub - sub x Sr sub x CuO sub 4 , demonstrating that the route to a high-T sub c superconductor is not unique. (author)

  13. Design of load-to-failure tests of high-voltage insulation breaks for ITER's cryogenic network

    Science.gov (United States)

    Langeslag, S. A. E.; Rodriguez Castro, E.; Aviles Santillana, I.; Sgobba, S.; Foussat, A.

    2015-12-01

    The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound with so-called cable-in-conduit conductors. The concept of the cable-in-conduit conductor is based on a direct cooling principle, by supercritical helium, flowing through the central region of the conductor, in close contact with the superconducting strands. Consequently, a direct connection exists between the electrically grounded helium coolant supply line and the highly energised magnet windings. Various insulated regions, constructed out of high-voltage insulation breaks, are put in place to isolate sectors with different electrical potential. In addition to high voltages and significant internal helium pressure, the insulation breaks will experience various mechanical forces resulting from differential thermal contraction phenomena and electro-magnetic loads. Special test equipment was designed, prepared and employed to assess the mechanical reliability of the insulation breaks. A binary test setup is proposed, where mechanical failure is assumed when leak rate of gaseous helium exceeds 10-9·Pa·m3/s. The test consists of a load-to-failure insulation break charging, in tension, while immersed in liquid nitrogen at the temperature of 77 K. Leak tightness during the test is monitored by measuring the leak rate of the gaseous helium, directly surrounding the insulation break, with respect to the existing vacuum inside the insulation break. The experimental setup is proven effective, and various insulation breaks performed beyond expectations.

  14. Better and cheaper extra insulation

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian

    1998-01-01

    of buildings. The thermal performance of the systems is compared to an ideal situation, showing that there is still a potential of further savings by improving the design of the insulation systems.To improve the thermal performance of the systems a number of product developments are proposed.......In the current energy plan, focus in placed on further savings of heat in buildings. If the target of the energy plan should be achieved, there is a need for saving heat both in new and existing buildings.The article investigate and compare the properties of several systems for external insulation...

  15. Aerogels Insulate Against Extreme Temperatures

    Science.gov (United States)

    2010-01-01

    In 1992, NASA started to pursue the development of aerogel for cryogenic insulation. Kennedy Space Center awarded Small Business Innovation Research (SBIR) contracts to Aspen Systems Inc., of Marlborough, Massachusetts, that resulted in a new manufacturing process and a new flexible, durable, easy-to-use form of aerogel. Aspen Systems formed Aspen Aerogels Inc., in Northborough, Massachusetts, to market the product, and by 2009, the company had become the leading provider of aerogel in the United States, producing nearly 20 million square feet per year. With an array of commercial applications, the NASA-derived aerogel has most recently been applied to protect and insulate people s hands and feet.

  16. LOCALIZATION OF TRANSCRIPTS OF THE RELATED NUCLEAR ORPHAN RECEPTORS COUP-TF-I AND ARP-1 IN THE ADULT-MOUSE BRAIN

    NARCIS (Netherlands)

    DASILVA, SL; COX, JJ; JONK, LJC; KRUIJER, W; BURBACH, JPH

    The chicken ovalbumin upstream promoter transcription factor, COUP-TF I, and the protein ARP-1 (COUP-TF II) are two highly homologous orphan receptors of the nuclear hormone receptor family. In this study we investigated their expression patterns in the adult nervous system of the mouse. In situ

  17. Development of superconducting magnets for magnetically levitated trains

    International Nuclear Information System (INIS)

    Ohno, E.; Iwamoto, M.; Ogino, O.; Kawamura, T.

    1974-01-01

    Superconducting magnets will play a vital role in magnetically levitated trains, producing lift, guidance and propulsion forces. The main problems in the design are the current density of coils and the cryogenic thermal insulation. This paper describes the development of full-scale levitation magnets with length of 1.55m and width of 0.3 or 0.5m. Dynamic levitation tests using small model magnets are also presented. (author)

  18. Improved differential diagnosis of anemia of chronic disease and iron deficiency anemia: a prospective multicenter evaluation of soluble transferrin receptor and the sTfR/log ferritin index.

    Science.gov (United States)

    Skikne, Barry S; Punnonen, Kari; Caldron, Paul H; Bennett, Michael T; Rehu, Mari; Gasior, Gail H; Chamberlin, Janna S; Sullivan, Linda A; Bray, Kurtis R; Southwick, Paula C

    2011-11-01

    Anemia of chronic disease (ACD) and iron deficiency anemia (IDA) are the most prevalent forms of anemia and often occur concurrently. Standard tests of iron status used in differential diagnosis are affected by inflammation, hindering clinical interpretation. In contrast, soluble transferrin receptor (sTfR) indicates iron deficiency and is unaffected by inflammation. Objectives of this prospective multicenter clinical trial were to evaluate and compare the diagnostic accuracy of sTfR and the sTfR/log ferritin index (sTfR Index) for differential diagnosis using the automated Access(®) sTfR assay (Beckman Coulter) and sTfR Index. We consecutively enrolled 145 anemic patients with common disorders associated with IDA and ACD. Subjects with IDA or ACD + IDA had significantly higher sTfR and sTfR Index values than subjects with ACD (P < 0.0001). ROC curves produced the following cutoffs for sTfR: 21 nmol/L (or 1.55 mg/L), and the sTfR Index: 14 (using nmol/L) (or 1.03 using mg/L). The sTfR Index was superior to sTfR (AUC 0.87 vs. 0.74, P < 0.0001). Use of all three parameters in combination more than doubled the detection of IDA, from 41% (ferritin alone) to 92% (ferritin, sTfR, sTfR Index). Use of sTfR and the sTfR Index improves detection of IDA, particularly in situations where routine markers provide equivocal results. Findings demonstrate a significant advantage in the simultaneous determination of ferritin, sTfR and sTfR Index. Obtaining a ferritin level alone may delay diagnosis of combined IDA and ACD. Copyright © 2011 Wiley-Liss, Inc.

  19. Commercial tokamak reactors with resistive toroidal field magnets

    International Nuclear Information System (INIS)

    Bombery, L.; Cohn, D.R.; Jassby, D.L.

    1984-01-01

    Scaling relations and design concepts are developed for commercial tokamak reactors that use watercooled copper toroidal field (TF) magnets. Illustrative parameters are developed for reactors that are scaled up in size from LITE test reactor designs, which use quasi-continuous copper plate magnets. Acceptably low magnet power requirements may be attainable in a moderate beta (β = 0.065) commercial reactor with a major radius of 6.2 m. The shielding thickness and magnet size are substantially reduced relative to values in commercial reactors with superconducting magnets. Operation at high beta (β = 0.14) leads to a reduction in reactor size, magnet-stored energy, and recirculating power. Reactors using resistive TF magnets could provide advantages of physically smaller devices, improved maintenance features, and increased ruggedness and reliability

  20. Inhomogeneous field induced magnetoelectric effect in Mott insulators

    Energy Technology Data Exchange (ETDEWEB)

    Boulaevskii, Lev N [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

    2008-01-01

    We consider a Mott insulator like HoMnO{sub 3} whose magnetic lattice is geometrically frustrated and comprises a 3D array of triangular layers with magnetic moments ordered in a 120{sup o} structure. We show that the effect of a uniform magnetic field gradient, {gradient}H, is to redistribute the electronic charge of the magnetically ordered phase leading to a unfirom electric field gradient. The resulting voltage difference between the crystal edges is proportional to the square of the crystal thickness, or inter-edge distance, L. It can reach values of several volts for |{gradient}H| {approx} 0.01 T/cm and L {approx_equal} 1mm, as long as the crystal is free of antiferromagnetic domain walls.

  1. An interim report on the materials and selection criteria analysis for the Compact Ignition Tokamak Toroidal Field Coil Turn-to-Turn Insulation System

    International Nuclear Information System (INIS)

    Campbell, V.W.; Dooley, J.B.; Hubrig, J.G.; Janke, C.J.; McManamy, T.J.; Welch, D.E.

    1990-01-01

    Design criteria for the Compact Ignition Tokamak, Toroidal-Field (TF) Coil, Turn-to-Turn Insulation System require an insulation sheet and bonding system that will survive cryogenic cycling in a radiation environment and maintain structural integrity during exposure to the significant compressive and shear loads associated with each operating cycle. For thermosetting resin systems, a complex interactive dependency exists between optimum peak value, in-service property performance capabilities of candidate generic materials; key handling and processing parameters required to achieve their optimum in-service property performance as an insulation system; and suitability of their handling and processing parameters as a function of design configuration and assembly methodology. This dependency is assessed in a weighted study matrix in which two principal programmatic approaches for the development of the TF Coil Subassembly Insulation System have been identified. From this matrix study, two viable approaches to the fabrication of the insulation sheet were identified: use of a press-formed sheet bonded in place with epoxy for mechanical bonding and tolerance take-up and formation of the insulation sheet by placement of dry cloth and subsequent vacuum pressure impregnation. Laboratory testing was conducted to screen a number of combinations of resins and hardeners on a generic basis. These combinations were chosen for their performance in similar applications. Specimens were tested to screen viscosity, thermal-shock tolerance, and cryogenic tolerance. Cryogenic shock and cryogenic temperature proved to be extremely lethal to many combinations of resin, hardener, and cure. Two combinations survived: a heavily flexibilized bisphenol A resin with a flexibilized amine hardener and a bisphenol A resin with cycloaliphatic amine hardener. 7 refs., 12 figs., 6 tabs

  2. Thermal insulation of fuel elements

    International Nuclear Information System (INIS)

    Dubrovcak, P.; Pec, V.; Pitonak, J.

    1978-01-01

    The claim of the invention concerns thermal insulation of fuel elements heated for measurement of uranium fuel physical properties. For this, layers of aluminium film and of glass fibre are wound onto the inner tube of the element cladding. The space between the inner and the outer tubes is evacuated and the tubes are spaced using spacer wires. (M.S.)

  3. Effects Of Radiation On Insulators

    Science.gov (United States)

    Bouquet, Frank L.

    1988-01-01

    Report presents data on responses of electrically insulating thermosetting and thermoplastic polymers to radiation. Lowest-threshold-dose (LTD) levels and 25-percent-change levels presented for such properties as tensile strength and electrical resistivity. Data on radiation-induced outgassing also given.

  4. SISTEM TEMU KEMBALI DOKUMEN TEKS DENGAN PEMBOBOTAN TF-IDF DAN LCS

    Directory of Open Access Journals (Sweden)

    Munjiah Nur Saadah

    2013-01-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Sistem temu kembali dokumen teks membutuhkan metode yang mampu mengembalikan sejumlah dokumen yang memiliki relevansi tinggi sesuai dengan permintaan pengguna. Salah satu tahapan penting dalam proses representasi teks adalah proses pembobotan. Penggunaan LCS dalam penyesuaian bobot Tf -Idf mempertimbangkan kemunculan urutan kata yang sama antara query dan teks di dalam dokumen. Adanya dokumen yang sangat panjang namun tidak relevan menyebabkan bobot yang dihasilkan tidak mampu merepresentasikan nilai relevansi dokumen. Penelitian ini mengusulkan penggunaan metode LCS yang memberikan bobot urutan kata dengan mempertimbangkan panjang dokumen terkait dengan rata-rata panjang dokumen dalam korpus. Metode ini mampu melakukan pengembalian dokumen teks secara efektif. Penambahan fitur urutan kata dengan normalisasi rasio panjang dokumen terhadap keseluruhan dokumen dalam korpus menghasilkan nilai presisi dan recall yang sama baiknya dengan metode sebelumnya.

  5. Optimization of time-of-flight reconstruction on Philips GEMINI TF

    International Nuclear Information System (INIS)

    Vandenberghe, Stefaan; Clementel, Enrico; Verhaeghe, Jeroen; Lemahieu, Ignace; Elmbt, Larry van; Bol, Anne; Lonneux, Max; Guerchaft, Michel

    2009-01-01

    The aim of this study is to optimize different parameters in the time-of-flight (TOF) reconstruction for the Philips GEMINI TF. The use of TOF in iterative reconstruction introduces additional variables to be optimized compared to conventional PET reconstruction. The different parameters studied are the TOF kernel width, the kernel truncation (used to reduce reconstruction time) and the scatter correction method. These parameters are optimized using measured phantom studies. All phantom studies were acquired with a very high number of counts to limit the effects of noise. A high number of iterations (33 subsets and 3 iterations) was used to reach convergence. The figures of merit are the uniformity in the background, the cold spot recovery and the hot spot contrast. As reference results we used the non-TOF reconstruction of the same data sets. It is shown that contrast recovery loss can only be avoided if the kernel is extended to more than 3 standard deviations. To obtain uniform reconstructions the recommended scatter correction is TOF single scatter simulation (SSS). This also leads to improved cold spot recovery and hot spot contrast. While the daily measurements of the system show a timing resolution in the range of 590-600 ps, the optimal reconstructions are obtained with a TOF kernel full-width at half-maximum (FWHM) of 650-700 ps. The optimal kernel width seems to be less critical for the recovered contrast but has an important effect on the background uniformity. Using smaller or wider kernels results in a less uniform background and reduced hot and cold contrast recovery. The different parameters studied have a large effect on the quantitative accuracy of the reconstructed images. The optimal settings from this study can be used as a guideline to make an objective comparison of the gains obtained with TOF PET versus PET reconstruction. (orig.)

  6. Oxotremorine treatment reduces repetitive behaviors in BTBR T+ tf/J mice

    Directory of Open Access Journals (Sweden)

    Dionisio A. Amodeo

    2014-08-01

    Full Text Available Repetitive behaviors with restricted interests is one of the core criteria for the diagnosis of autism spectrum disorder (ASD. Current pharmacotherapies that target the dopaminergic or serotonergic systems have limited effectiveness in treating repetitive behaviors. Previous research has demonstrated that administration of muscarinic cholinergic receptor (mAChR antagonists can exacerbate motor stereotypies while mAChR agonists reduce stereotypies. The present study determined whether the mAChR agonist, oxotremorine affected repetitive behaviors in the BTBR T+ tf/J (BTBR mouse model of autism. To test the effects of oxotremorine on repetitive behaviors, marble burying and grooming behavior were measured in BTBR mice and compared to that in C57BL/6J (B6 mice. The effects of oxotremorine on locomotor activity was also measured. Thirty minutes before each test, mice received an intraperitoneal injection of saline, 0.001 mg or 0.01 mg of oxotremorine methiodide. Saline- treated BTBR mice exhibited increased marble burying and self-grooming behavior compared to that of saline-treated B6 mice. Oxotremorine significantly reduced marble burying and self-grooming behavior in BTBR mice, but had no significant effect in B6 mice. In addition, oxotremorine did not affect locomotor activity in BTBR mice, but significantly reduced locomotor activity in B6 mice at the 0.01 mg dose. These findings demonstrate that activation of mAChRs reduces repetitive behavior in the BTBR mouse and suggest that treatment with a mAChR agonist may be effective in reducing repetitive behaviors in ASD.

  7. Pacer Comet 4: Automated Jet Engine Testing of a TF33-P100 Pratt & Whitney Engine

    Science.gov (United States)

    Mason, Rex Bolding

    Pacer Comet 4 found its life out of necessity to replace an obsolescent Pacer Comet 3 engine test system at Tinker AFB in Oklahoma City, OK. Pacer Comet 3 (PC3) was created and installed in the early 1980's to test jet engines from a wide range of planes. PC3 had several problems from a maintenance standpoint: contractors designed and installed the system but the contract did not include the OEM data package. Without drawings or design knowledge, fixing the smallest of problems could turn into a multi-day project. In addition to high cost, as the OEM companies of proprietary parts went out of business, it became impossible to find a replacement for a failed part. These issues set the framework for the Pacer Comet 4 (PC4) system. PC4 was created as an organic AF and Department of Defense collaboration to fix the issues with PC3. PC4 provides the customer with a complete data package including multiple drawing sets and data sheets for all parts used, as well as design files for all PCBs created in house. PC4 has a standard to use commercially available off the shelf parts (COTS). The reason for this is sustainability in maintenance. If a part is to fail, it should be able to be purchased from any manufacturer that meets the specs of the original product. No proprietary parts are used, except as directed by the engine's OEM. This thesis will focus on the design and installation of the on-frame data acquisition PC4 system for the Pratt & Whitney TF33-P100A-QEC engine that is currently in use on the E3 Sentry. This thesis will show efficiency improvements for maintenance sustainability (70% cabling reduction) as well as discuss performance improvements in both test and production environments.

  8. Polyimide Foams Offer Superior Insulation

    Science.gov (United States)

    2012-01-01

    At Langley Research Center, Erik Weiser and his colleagues in the Advanced Materials and Processing Branch were working with a new substance for fabricating composites for use in supersonic aircraft. The team, however, was experiencing some frustration. Every time they tried to create a solid composite from the polyimide (an advanced polymer) material, it bubbled and foamed. It seemed like the team had reached a dead end in their research - until they had another idea. "We said, This isn t going to work for composites, but maybe we could make a foam out of it," Weiser says. "That was kind of our eureka moment, to see if we could go in a whole other direction. And it worked." Weiser and his colleagues invented a new kind of polyimide foam insulation they named TEEK. The innovation displayed a host of advantages over existing insulation options. Compared to other commercial foams, Weiser explains, polyimide foams perform well across a broad range of temperatures, noting that the NASA TEEK foams provide effective structural insulation up to 600 F and down to cryogenic temperatures. The foam does not burn or off-gas toxic fumes, and even at -423 F - the temperature of liquid hydrogen - the material stays flexible. The inventors could produce the TEEK foam at a range of densities, from 0.5 pounds per cubic foot up to 20 pounds per cubic foot, making the foam ideal for a range of applications, including as insulation for reusable launch vehicles and for cryogenic tanks and lines. They also developed a unique, friable balloon format for manufacturing the foam, producing it as hollow microspheres that allowed the foam to be molded and then cured into any desired shape - perfect for insulating pipes of different sizes and configurations. The team s originally unplanned invention won an "R&D 100" award, and a later form of the foam, called LaRC FPF-44 (Spinoff 2009), was named "NASA Invention of the Year" in 2007.

  9. HEAT TRANSFER THROUGH CYANATE ESTER EPOXY MIX AND EPOXY GPAP–DETDA ELECTRICAL INSULATIONS AT SUPERFLUID HELIUM TEMPERATURE

    CERN Document Server

    Pietrowicz, S; Canfer, S; Jones, S; Baudouy, B

    2011-01-01

    In the framework of the European project EuCARD (FP7) aiming at constructing a high magnetic field accelerator magnet of 13 T with Nb3Sn superconducting cables, new electrical insulation are thermally tested. This technology will use “conventional” electrical insulation in combination with pressurized superfluid helium (He II) or saturated helium at atmospheric pressure as coolant. Two composite insulation systems composed of cyanate ester epoxy mix or a tri-functional epoxy (TGPAP-DETDA) with fiberglass tape frame, have been chosen as potential candidates. The knowledge of their thermal properties is necessary for the thermal design and therefore samples have been tested in pressurized He II where heat is applied perpendicularly to the fibers between 1.6 K and 2.0 K. Overall thermal resistance is determined as a function of temperature and the results are compared with other electrical insulation systems used for accelerator magnets.

  10. Design of load-to-failure tests of high-voltage insulation breaks for ITER's cryogenic network

    CERN Document Server

    Langeslag, S A E; Aviles Santillana, I; Sgobba, S; Foussat, A

    2015-01-01

    The development of new generation superconducting magnets for fusion research, such as the ITER experiment, is largely based on coils wound with so-called cable-in-conduit conductors. The concept of the cable-in-conduit conductor is based on a direct cooling principle, by supercritical helium, flowing through the central region of the conductor, in close contact with the superconducting strands. Consequently, a direct connection exists between the electrically grounded helium coolant supply line and the highly energised magnet windings. Various insulated regions, constructed out of high-voltage insulation breaks, are put in place to isolate sectors with different electrical potential. In addition to high voltages and significant internal helium pressure, the insulation breaks will experience various mechanical forces resulting from differential thermal contraction phenomena and electro-magnetic loads. Special test equipment was designed, prepared and employed to assess the mechanical reliability of the insul...

  11. Implementation of non-condensable gases condensation suppression model into the WCOBRA/TRAC-TF2 LOCA safety evaluation code

    International Nuclear Information System (INIS)

    Liao, J.; Cao, L.; Ohkawa, K.; Frepoli, C.

    2012-01-01

    The non-condensable gases condensation suppression model is important for a realistic LOCA safety analysis code. A condensation suppression model for direct contact condensation was previously developed by Westinghouse using first principles. The model is believed to be an accurate description of the direct contact condensation process in the presence of non-condensable gases. The Westinghouse condensation suppression model is further revised by applying a more physical model. The revised condensation suppression model is thus implemented into the WCOBRA/TRAC-TF2 LOCA safety evaluation code for both 3-D module (COBRA-TF) and 1-D module (TRAC-PF1). Parametric study using the revised Westinghouse condensation suppression model is conducted. Additionally, the performance of non-condensable gases condensation suppression model is examined in the ACHILLES (ISP-25) separate effects test and LOFT L2-5 (ISP-13) integral effects test. (authors)

  12. Fusion of Potentiometric & Voltammetric Electronic Tongue for Classification of Black Tea Taste based on Theaflavins (TF) Content

    Science.gov (United States)

    Bhattacharyya, Nabarun; Legin, Andrey; Papieva, Irina; Sarkar, Subrata; Kirsanov, Dmitry; Kartsova, Anna; Ghosh, Arunangshu; Bandyopadhyay, Rajib

    2011-09-01

    Black tea is an extensively consumed beverage worldwide with an expanding market. The final quality of black tea depends upon number of chemical compounds present in the tea. Out of these compounds, theaflavins (TF), which is responsible for astringency in black tea, plays an important role in determining the final taste of the finished black tea. The present paper reports our effort to correlate the theaflavins contents with the voltammetric and potentiometric electronic tongue (e-tongue) data. Noble metal-based electrode array has been used for collecting data though voltammetric electronic tongue where as liquid filled membrane based electrodes have been used for potentiometric electronic tongue. Black tea samples with tea taster score and biochemical results have been collected from Tea Research Association, Tocklai, India for the analysis purpose. In this paper, voltammetric and potentiometric e-tongue responses are combined to demonstrate improvement of cluster formation among tea samples with different ranges of TF values.

  13. Anaplastic Thyroid Carcinoma: Current Treatments and Potential New Therapeutic Options with Emphasis on TfR1/CD71

    Directory of Open Access Journals (Sweden)

    Rosalba Parenti

    2014-01-01

    Full Text Available Anaplastic thyroid carcinoma (ATC is one of the most aggressive human cancers. Actually, ATC is refractory to conventional therapies, including surgery, chemotherapy, radiotherapy, and radioiodine (131I therapy. Accordingly, genetic and molecular characterizations of ATC have been frequently and periodically reviewed in order to identify potential biological markers exploitable for target therapy. This review briefly focuses on main molecular events that characterize ATC and provides an update about preclinical studies. In addition, the overexpression of transferrin receptor 1 (TfR1/CD71 by neoplastic cells of ATC is emphasized in that it could represent a potential therapeutic target. In this regard, new therapeutic approaches based on the use of monoclonal or recombinant antibodies, or transferrin-gallium-TfR1/CD71 molecular complexes, or lastly small interfering RNAs (siRNAs are proposed.

  14. Thermal analysis of the forced cooled conductor for the TF [toroidal field] superconducting coils in the TIBER II ETR design

    International Nuclear Information System (INIS)

    Kerns, J.A.; Slack, D.S.; Miller, J.R.

    1987-01-01

    The Tokamak Ignition/Burn Experimental Reactor (TIBER) is being designed to provide nuclear testing capabilities for first wall and blanket design concepts. The baseline design for TIBER II is to provide steady-state nuclear burn capabilities. These objectives must be met using reactor relevant components, such as state-of-the-art current drive schemes coupled with superconducting toroidal field (TF) and poloidal field (PF) coils. The design is also constrained to be cost effective, which forces the machine to be as small as possible. This last constraint limits the nuclear shielding in TIBER. Therefore, the TF coils will have a high nuclear heat load of up to 4.5 kW per coil. The cooling scheme and the thermal analysis for this design are presented

  15. A Method to Predict Compressor Stall in the TF34-100 Turbofan Engine Utilizing Real-Time Performance Data

    Science.gov (United States)

    2015-06-01

    pass turbo –fan engine sensor data to seek its deterioration modelling and prognostics capability. In futurity this will allow for achievement of...preventive maintenance for the TF34-100 jet engine to prevent engine compressor stalls for the A-10 aircraft. Due to their destructive nature, compressor...stalls are a significant concern in axial flow compressor jet engines. A compressor stall is caused by air approaching the compressor blades at an

  16. Tunneling Planar Hall Effect in Topological Insulators: Spin Valves and Amplifiers.

    Science.gov (United States)

    Scharf, Benedikt; Matos-Abiague, Alex; Han, Jong E; Hankiewicz, Ewelina M; Žutić, Igor

    2016-10-14

    We investigate tunneling across a single ferromagnetic barrier on the surface of a three-dimensional topological insulator. In the presence of a magnetization component along the bias direction, a tunneling planar Hall conductance (TPHC), transverse to the applied bias, develops. Electrostatic control of the barrier enables a giant Hall angle, with the TPHC exceeding the longitudinal tunneling conductance. By changing the in-plane magnetization direction, it is possible to change the sign of both the longitudinal and transverse differential conductance without opening a gap in the topological surface state. The transport in a topological-insulator-ferromagnet junction can, thus, be drastically altered from a simple spin valve to an amplifier.

  17. Ultra-low loss nano-taper coupler for Silicon-on-Insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan

    2010-01-01

    A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler.......A nano-taper coupler is optimized specially for the transverse-magnetic mode for interfacing light between a silicon-on-insulator ridge waveguide and a single-mode fiber. An ultra-low coupling loss of ~0.36dB is achieved for the nano-taper coupler....

  18. Spin-orbit torque in two-dimensional antiferromagnetic topological insulators

    KAUST Repository

    Ghosh, Sumit

    2017-01-24

    We investigate spin transport in two-dimensional ferromagnetic (FTI) and antiferromagnetic (AFTI) topological insulators. In the presence of an in-plane magnetization AFTI supports zero energy modes, which enables topologically protected edge conduction at low energy. We address the nature of current-driven spin torque in these structures and study the impact of spin-independent disorder. Interestingly, upon strong disorder the spin torque develops an antidamping component (i.e., even upon magnetization reversal) along the edges, which could enable current-driven manipulation of the antiferromagnetic order parameter. This antidamping torque decreases when increasing the system size and when the system enters the trivial insulator regime.

  19. Non-nuclear Testing of Reactor Systems in the Early Flight Fission Test Facilities (EFF-TF)

    Science.gov (United States)

    VanDyke, Melissa; Martin, James

    2004-01-01

    The Early Flight Fission-Test Facility (EFF-TF) can assist in the &sign and development of systems through highly effective non-nuclear testing of nuclear systems when technical issues associated with near-term space fission systems are "non-nuclear" in nature (e.g. system s nuclear operations are understood). For many systems. thermal simulators can he used to closely mimic fission heat deposition. Axial power profile, radial power profile. and fuel pin thermal conductivity can be matched. In addition to component and subsystem testing, operational and lifetime issues associated with the steady state and transient performance of the integrated reactor module can be investigated. Instrumentation at the EFF-TF allows accurate measurement of temperature, pressure, strain, and bulk core deformation (useful for accurately simulating nuclear behavior). Ongoing research at the EFF-TF is geared towards facilitating research, development, system integration, and system utilization via cooperative efforts with DOE laboratories, industry, universities, and other NASA centers. This paper describes the current efforts for the latter portion of 2003 and beginning of 2004.

  20. Insulator recognition based on convolution neural network

    Directory of Open Access Journals (Sweden)

    Yang Yanli

    2017-01-01

    Full Text Available Insulator fault detection plays an important role in maintaining the safety of transmission lines. Insulator recognition is a prerequisite for its fault detection. An insulator recognition algorithm based on convolution neural network (CNN is proposed. A dataset is established to train the constructed CNN. The correct rate is 98.52% for 1220 training samples and the accuracy rate of testing is 89.04% on 1305 samples. The classification result of the CNN is further used to segment the insulator image. The test results show that the proposed method can realize the effective segmentation of insulators.

  1. Design analysis of ceramic and polymer 150 kV insulators for tropical condition using quickfield software

    Science.gov (United States)

    Walukow, Stephy B.; Manjang, Salama; Zainuddin, Zahir; Samman, Faizal Arya

    2018-03-01

    This research is to analyze design of ceramic and polymer 150 kV insulators for the tropical area. The use of an insulator certainly requires an electric field. The leakage current and breakdown voltage this happens the contaminant on the surface of the insulator. This type of contaminant can be rain, dust, salt air, extreme weather (much in tropical climates), industrial pollutants and cracks on the surface resulting in collisions. The method used in this research is magnetic field and electric field isolator using Quicfield software. To get the test results variation ranges 20 kV, 70 kV and 150 kV. Side effects of magnetic and electric fields around the insulator. The simulation results show the accumulated contaminants on the surface. Planning should be done in insulator insulator on unstable insulator. Thus, the approach using this commercially available software can be applied to. Therefore, the development of further simulations on the different types of composite insulators used on.

  2. Characterization of low temperature high voltage axial insulator breaks for the ITER cryogenic supply line

    Science.gov (United States)

    Fernandez Pison, P.; Sgobba, S.; Aviles Santillana, I.; Langeslag, S. A. E.; Su, M.; Piccin, R.; Journeaux, J. Y.; Laurenti, A.; Pan, W.

    2017-12-01

    Cable-in-conduit conductors of the ITER magnet system are directly cooled by supercritical helium. Insulation breaks are required in the liquid helium feed pipes to isolate the high voltage system of the magnet windings from the electrically grounded helium coolant supply line. They are submitted to high voltages and significant internal helium pressure and will experience mechanical forces resulting from differential thermal contraction and electro-mechanical loads. Insulation breaks consist essentially of stainless steel tubes overwrapped by an outer glass – fiber reinforced composite and bonded to an inner composite tube at each end of the stainless steel fittings. For some types of insulator breaks Glass – Kapton – Glass insulation layers are interleaved in the outer composite. Following an extensive mechanical testing campaign at cryogenic temperature combined with leak tightness tests, the present paper investigates through non-destructive and destructive techniques the physical and microstructural characteristics of the low temperature high voltage insulation breaks and of their individual components, thus allowing to correlate the structure and properties of the constituents to their overall performance. For all the tests performed, consistent and reproducible results were obtained within the range of the strict acceptance criteria defined for safe operation of the insulation breaks.

  3. Direct observation of quantum superconducting fluctuations across the 2D superconductor-insulator transition

    International Nuclear Information System (INIS)

    Armitage, N.P.; Crane, R.W.; Sambandamurthy, G.; Johansson, A.; Shahar, D.; Zaretskey, V.; Gruener, G.

    2008-01-01

    We review our recent measurements of the complex AC conductivity of thin InO x films studied as a function of magnetic field through the nominal 2D superconductor-insulator transition. These measurements-the first to probe anything other than the ω=0 response of these archetypical systems-reveal a significant finite frequency superfluid stiffness well into the insulating regime. Unlike conventional fluctuation superconductivity in which thermal fluctuations can give a superconducting response in regions of parameter space that do not exhibit long range order, these fluctuations are temperature independent as T→0 and are exhibited in samples where the resistance is large (greater than 10 6 Ω/□) and strongly diverging. We interpret this as the first direct observation of quantum superconducting fluctuations around an insulating ground state. This system serves as a prototype for other insulating states of matter that derive from superconductors

  4. High temperature structural insulating material

    Science.gov (United States)

    Chen, W.Y.

    1984-07-27

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800/sup 0/C), low thermal conductivity (below about 0.2 W/m/sup 0/C), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800/sup 0/C, a diameter within the range of 20-200 ..mu..m, and a wall thickness in the range of about 2 to 4 ..mu..m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  5. Effect of Twist Pitch in the Strands on the Saturation and Losses in the Nb3Sn Strands for the ITER TF CICC

    Energy Technology Data Exchange (ETDEWEB)

    Martovetsky, N N

    2007-12-06

    ITER TF coils will see a significant longitudinal magnetic field in the event of the plasma disruption. This abrupt change of magnetic fields results in the appearance of an additional electrical field in the strands. The mechanism of this electrical field is the induced currents that expel the flux from the strands. This effect was known since the late 1970's [1-3] and most of the details necessary for the analyses given in this report are presented in [4]. Let's assume for simplicity a zero transport current in the strand. When a longitudinal pulsed field is applied, the outer filaments will carry an induced current repelling the change of flux. The current density of this current is 'critical' in the simplification of Bean's critical state model, where superconducting transition is represented as j=j{sub c} at any non-zero electrical field and zero where the electrical field has not penetrated. In reality, since the current density is roughly logarithmic with the electrical field, E=E{sub c}*exp[(j-j{sub c})/jo], Bean's model is just a simplification, and current density is slightly nonuniform in the outer filament and more so for the interior strands. The inner portion of the filaments will carry a current of the opposite sign. Even in the Bean's model it is not uniform, but the assumption that it is uniform and less than critical simplifies mathematics significantly and does not deviate far from the real current density distribution. In certain circumstances, the average electrical field in the strands will be high enough to exceed the take-off electrical field averaged across the cross section. In this case, the multifilamentary strand will become unstable and will experience transition to the normal state. With zero transport current, it will eventually recover, of course. This phenomenon is analogous to the flux jump. If the strand carries a transport current, the situation becomes more complicated. If it goes unstable and

  6. Performance of Topological Insulator Interconnects

    OpenAIRE

    Philip, Timothy M.; Hirsbrunner, Mark R.; Park, Moon Jip; Gilbert, Matthew J.

    2016-01-01

    The poor performance of copper interconnects at the nanometer scale calls for new material solutions for continued scaling of integrated circuits. We propose the use of three dimensional time-reversal-invariant topological insulators (TIs), which host backscattering-protected surface states, for this purpose. Using semiclassical methods, we demonstrate that nanoscale TI interconnects have a resistance 1-3 orders of magnitude lower than copper interconnects and graphene nanoribbons at the nano...

  7. Modified small angle magnetization rotation method in multilayer magnetic microwires

    International Nuclear Information System (INIS)

    Torrejon, J.; Badini, G.; Pirota, K.; Vazquez, M.

    2007-01-01

    The small angle magnetization rotation (SAMR) technique is a widely used method to quantify magnetostriction in elongated ultrasoft magnetic materials. In the present work, we introduce significant optimization of the method, particularly simplification of the required equipment, profiting of the very peculiar characteristics of a recently introduced family of multilayer magnetic microwires consisting of a soft magnetic core, insulating intermediate layer and a hard magnetic outer layer. The introduced modified SAMR method is used not only to determine the saturation magnetostriction constant of the soft magnetic nucleus but also the magnetoelastic and magnetostatic coupling. This new method has a great potential in multifunctional sensor applications

  8. Secondary electron emission from insulators

    International Nuclear Information System (INIS)

    Kanaya, K.; Ono, S.; Ishigaki, F.

    1978-01-01

    The high yield of secondary electron emission from insulators due to electron bombardment may be the result of an increase of the depth of escape. The free-electron scattering theory is applied to the high energy of primary beams, but cannot be applied to the low energy of secondary escaping beams because of the large energy gap of the insulators. The plasmon loss with the valence electron is considered when the secondary electrons escape. Based on the energy retardation power formula of the penetration and energy loss of an electron probe into solid targets, secondary electron emissions from insulators are calculated from the assumptions that the distribution of the secondary electrons due to both incident and back-scattered electrons within the target is isotropic and that it follows the absorption law of the Lenard type. The universal yield-energy curve of the secondary electron emission, which is deduced as a function of three parameters such as ionisation potential, valence electron and the back-scattered coefficient in addition to the free-electron density effect, is found to be in good agreement with the experimental results. (author)

  9. Small polaron hopping in magnetic semiconductors

    International Nuclear Information System (INIS)

    Emin, D.; Liu, N.L.H.

    1978-01-01

    In a number of magnetic insulators it has been hypothesized that the charge carriers form small polarons. The transfer of an electron between magnetic sites and how the magnetic nature of the material affects the rate which characterizes small-polaron hops between magnetic sites were studied. The basic transfer processes are addressed from a many-electron point in which the itinerant electron is treated as indistinguishable from those which contribute unpaired spins at the magnetic sites

  10. Insulator-insulator and insulator-conductor transitions in the phase diagram of aluminium trichloride

    Directory of Open Access Journals (Sweden)

    Romina Ruberto

    2009-01-01

    Full Text Available We report a classical computer-simulation study of the phase diagram of AlCl3 in the pressure-temperature (p, T plane, showing (i that melting from a layered crystal structure occurs into a molecular liquid at low (p, T and into a dissociated ionic liquid at high (p, T, and (ii that a broad transition from a molecular insulator to an ionic conductor takes place in the liquid state.

  11. Ultra-low-loss inverted taper coupler for silicon-on-insulator ridge waveguide

    DEFF Research Database (Denmark)

    Pu, Minhao; Liu, Liu; Ou, Haiyan

    2010-01-01

    An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering...... the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler...... for transverse-magnetic and transverse-electric modes are ~0.36 dB and ~0.66 dB per connection, respectively....

  12. Edge states and integer quantum Hall effect in topological insulator thin films.

    Science.gov (United States)

    Zhang, Song-Bo; Lu, Hai-Zhou; Shen, Shun-Qing

    2015-08-25

    The integer quantum Hall effect is a topological state of quantum matter in two dimensions, and has recently been observed in three-dimensional topological insulator thin films. Here we study the Landau levels and edge states of surface Dirac fermions in topological insulators under strong magnetic field. We examine the formation of the quantum plateaux of the Hall conductance and find two different patterns, in one pattern the filling number covers all integers while only odd integers in the other. We focus on the quantum plateau closest to zero energy and demonstrate the breakdown of the quantum spin Hall effect resulting from structure inversion asymmetry. The phase diagrams of the quantum Hall states are presented as functions of magnetic field, gate voltage and chemical potential. This work establishes an intuitive picture of the edge states to understand the integer quantum Hall effect for Dirac electrons in topological insulator thin films.

  13. Large Coil Program magnetic system design study

    International Nuclear Information System (INIS)

    Moses, S.D.; Johnson, N.E.

    1977-01-01

    The primary objective of the Large Coil Program (LCP) is to demonstrate the reliable operation of large superconducting coils to provide a basis for the design principles, materials, and fabrication techniques proposed for the toroidal magnets for the THE NEXT STEP (TNS) and other future tokamak devices. This paper documents a design study of the Large Coil Test Facility (LCTF) in which the structural response of the Toroidal Field (TF) Coils and the supporting structure was evaluated under simulated reactor conditions. The LCP test facility structural system consists of six TF Coils, twelve coil-to-coil torsional restraining beams (torque rings), a central bucking post with base, and a Pulse Coil system. The NASTRAN Finite Element Structural Analysis computer Code was utilized to determine the distribution of deflections, forces, and stresses for each of the TF Coils, torque rings, and the central bucking post. Eleven load conditions were selected to represent probable test operations. Pulse Coils suspended in the bore of the test coil were energized to simulate the pulsed field environment characteristic of the TNS reactor system. The TORMAC Computer Code was utilized to develop the magnetic forces in the TF Coils for each of the eleven loading conditions examined, with or without the Pulse Coils energized. The TORMAC computer program output forces were used directly as input load conditions for the NASTRAN analyses. Results are presented which demonstrate the reliability of the LCTF under simulated reactor operating conditions

  14. Development of burnup dependent fuel rod model in COBRA-TF

    Science.gov (United States)

    Yilmaz, Mine Ozdemir

    The purpose of this research was to develop a burnup dependent fuel thermal conductivity model within Pennsylvania State University, Reactor Dynamics and Fuel Management Group (RDFMG) version of the subchannel thermal-hydraulics code COBRA-TF (CTF). The model takes into account first, the degradation of fuel thermal conductivity with high burnup; and second, the fuel thermal conductivity dependence on the Gadolinium content for both UO2 and MOX fuel rods. The modified Nuclear Fuel Industries (NFI) model for UO2 fuel rods and Duriez/Modified NFI Model for MOX fuel rods were incorporated into CTF and fuel centerline predictions were compared against Halden experimental test data and FRAPCON-3.4 predictions to validate the burnup dependent fuel thermal conductivity model in CTF. Experimental test cases from Halden reactor fuel rods for UO2 fuel rods at Beginning of Life (BOL), through lifetime without Gd2O3 and through lifetime with Gd 2O3 and a MOX fuel rod were simulated with CTF. Since test fuel rod and FRAPCON-3.4 results were based on single rod measurements, CTF was run for a single fuel rod surrounded with a single channel configuration. Input decks for CTF were developed for one fuel rod located at the center of a subchannel (rod-centered subchannel approach). Fuel centerline temperatures predicted by CTF were compared against the measurements from Halden experimental test data and the predictions from FRAPCON-3.4. After implementing the new fuel thermal conductivity model in CTF and validating the model with experimental data, CTF model was applied to steady state and transient calculations. 4x4 PWR fuel bundle configuration from Purdue MOX benchmark was used to apply the new model for steady state and transient calculations. First, one of each high burnup UO2 and MOX fuel rods from 4x4 matrix were selected to carry out single fuel rod calculations and fuel centerline temperatures predicted by CTF/TORT-TD were compared against CTF /TORT-TD /FRAPTRAN

  15. Conceptual design Alcator C-MOD magnetic systems

    International Nuclear Information System (INIS)

    Schultz, J.H.; Becker, H.; Fertl, K.; Gwinn, D.; Montgomery, D.B.; Pierce, N.T.; Pillsbury, R.D. Jr.; Thome, R.J.

    1986-01-01

    The conceptual designs of the magnetic systems for Alcator C-MOD, a proposed tokamak at M.I.T., are described, including the toroidal magnet, the poloidal field coils and the cryogenic system. The toroidal magnet is constructed from rectangular plates, connected by sliding joints. Toroidal magnet forces are contained by a steel superstructure. Poloidal coil system options are largely or wholly inside the TF magnet, in order to control plasmas with high current, strong shaping, and expanded boundaries. All magnets are cryocooled by the natural circulation of boiling liquid nitrogen. 3 refs., 5 figs

  16. Fermi surface in the absence of a Fermi liquid in the Kondo insulator SmB6

    Science.gov (United States)

    Hartstein, M.; Toews, W. H.; Hsu, Y.-T.; Zeng, B.; Chen, X.; Hatnean, M. Ciomaga; Zhang, Q. R.; Nakamura, S.; Padgett, A. S.; Rodway-Gant, G.; Berk, J.; Kingston, M. K.; Zhang, G. H.; Chan, M. K.; Yamashita, S.; Sakakibara, T.; Takano, Y.; Park, J.-H.; Balicas, L.; Harrison, N.; Shitsevalova, N.; Balakrishnan, G.; Lonzarich, G. G.; Hill, R. W.; Sutherland, M.; Sebastian, Suchitra E.

    2018-02-01

    The search for a Fermi surface in the absence of a conventional Fermi liquid has thus far yielded very few potential candidates. Among promising materials are spin-frustrated Mott insulators near the insulator-metal transition, where theory predicts a Fermi surface associated with neutral low-energy excitations. Here we reveal another route to experimentally realize a Fermi surface in the absence of a Fermi liquid by the experimental study of a Kondo insulator SmB6 positioned close to the insulator-metal transition. We present experimental signatures down to low temperatures (thermal conductivity well below the charge gap energy scale. Thus, the weight of evidence indicates that despite an extreme instance of Fermi liquid breakdown in Kondo insulating SmB6, a Fermi surface arises from novel itinerant low-energy excitations that couple to magnetic fields, but not weak DC electric fields.

  17. Value of Soluble Transferrin Receptors and sTfR/log Ferritin in the Diagnosis of Iron Deficiency Accompanied by Acute Infection.

    Science.gov (United States)

    El-Gendy, Fady M; El-Hawy, Mahmoud A; Rizk, Mohamed S; El-Hefnawy, Sally M; Mahmoud, Mohamed Z

    2018-01-01

    There are many causes of anemia; the most common of these are acute and chronic infections, iron deficiency, or both. Identifying the cause is a very important step in management of anemia. So, we evaluated the usefulness of soluble transferrin receptor (sTfR) and of the sTfR/log ferritin in the diagnosis of iron deficiency anemia accompanied by acute infection. This study was conducted on 131 children aged 2-11 years old from those who attended the pediatric outpatient clinics in Menoufia university hospital. Hematological indices, iron balance and sTfR were evaluated and the sTfR/log F was calculated for each examined child. From the examined children four groups were distinguished : Group I (control): included 34 healthy children with normal iron status (66.7% males, age 4.2 ± 1.2). Group II (IDA): included 38 children diagnosed as iron deficiency anemia (47.4% males, age 4.9 ± 1.6). Group III (IDA + infection): included 26 children with infectious disease (upper respiratory tract infection, otitis media, pneumonia, stomatitis, and urinary tract infection) and anemia meeting criteria of IDA (50% males, age 4.2 ± 0.7). Group IV (anemia + infection): included 33 children with infectious anemia without iron deficiency (56.2% males, age 5.06 ± 1.4). It was proved that sTfR and sTfR/log Ferritin were significantly higher in children with anemia due to iron deficiency, and in those with infection + iron deficiency, versus those with infectious anemia or in healthy children. The use of sTfR and sTfR/log ferritin improves the diagnosis of IDA in pediatric patients, especially in the presence of coexisting acute infection.

  18. WISE TF: A MID-INFRARED, 3.4 μm EXTENSION OF THE TULLY-FISHER RELATION USING WISE PHOTOMETRY

    International Nuclear Information System (INIS)

    Lagattuta, David J.; Mould, Jeremy R.; Staveley-Smith, Lister; Hong Tao; Springob, Christopher M.; Masters, Karen L.; Koribalski, Bärbel S.; Jones, D. Heath

    2013-01-01

    We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4 μm W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M corr = –22.24 – 10.05[log (W corr ) – 2.5], with an average dispersion of σ WISE = 0.686 mag. There is some tension between WISE TF and a preliminary 3.6 μm relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K – W1) ∼ 0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile.

  19. Dirac spin-orbit torques and charge pumping at the surface of topological insulators

    KAUST Repository

    Ndiaye, Papa Birame

    2017-07-07

    We address the nature of spin-orbit torques at the magnetic surfaces of topological insulators using the linear-response theory. We find that the so-called Dirac torques in such systems possess a different symmetry compared to their Rashba counterpart, as well as a high anisotropy as a function of the magnetization direction. In particular, the damping torque vanishes when the magnetization lies in the plane of the topological-insulator surface. We also show that the Onsager reciprocal of the spin-orbit torque, the charge pumping, induces an enhanced anisotropic damping. Via a macrospin model, we numerically demonstrate that these features have important consequences in terms of magnetization switching.

  20. Spin dynamics of the Kondo insulator CeNiSn approaching the metallic phase

    DEFF Research Database (Denmark)

    Schröder, A.; Aeppli, G.; Mason, T.E.

    1997-01-01

    The spin dynamics of Kondo insulators has been studied by high-resolution magnetic neutron spectroscopy at a triple-axes spectrometer on CeNi1-xCuxSn single crystals using a vertical 9 T magnet. While upon doping (x = 0.13) the spin gap of the Kondo insulator CeNiSn collapses at the transition...... to an antiferromagnetic ordered metallic Kondo compound, no such instability is observed in CeNiSn in magnetic fields up to 9 T. Both the sharp magnetic excitations (at 2 and 4 meV) appear significantly broader for energy and momentum transfer at high fields, while the ground-state correlations (probed by chi'(0)) remain...

  1. Thermal Insulation Strips Conserve Energy

    Science.gov (United States)

    2009-01-01

    Launching the space shuttle involves an interesting paradox: While the temperatures inside the shuttle s main engines climb higher than 6,000 F hot enough to boil iron for fuel, the engines use liquid hydrogen, the second coldest liquid on Earth after liquid helium. Maintained below 20 K (-423 F), the liquid hydrogen is contained in the shuttle s rust-colored external tank. The external tank also contains liquid oxygen (kept below a somewhat less chilly 90 K or -297 F) that combines with the hydrogen to create an explosive mixture that along with the shuttle s two, powdered aluminum-fueled solid rocket boosters allows the shuttle to escape Earth s gravity. The cryogenic temperatures of the main engines liquid fuel can cause ice, frost, or liquefied air to build up on the external tank and other parts of the numerous launch fueling systems, posing a possible debris risk when the ice breaks off during launch and causing difficulties in the transfer and control of these cryogenic liquid propellants. Keeping the fuel at the necessary ultra-cold temperatures while minimizing ice buildup and other safety hazards, as well as reducing the operational maintenance costs, has required NASA to explore innovative ways for providing superior thermal insulation systems. To address the challenge, the Agency turned to an insulating technology so effective that, even though it is mostly air, a thin sheet can prevent a blowtorch from igniting a match. Aerogels were invented in 1931 and demonstrate properties that make them the most extraordinary insulating materials known; a 1-inch-thick piece of aerogel provides the same insulation as layering 15 panes of glass with air pockets in between. Derived from silica, aluminum oxide, or carbon gels using a supercritical drying process - resulting in a composition of almost 99-percent air - aerogels are the world s lightest solid (among 15 other titles they hold in the Guinness World Records), can float indefinitely on water if treated to be

  2. Pressure-driven metal-insulator transition in hematite from dynamical mean-field theory

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Korotin, D. M.; Korotin, M. A.; Anisimov, V.I.; Werner, P.

    2009-01-01

    Roč. 102, č. 14 (2009), 146402/1-146402/4 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z10100521 Keywords : metal-insulator transitions and other electronic transitions * strongly correlated electron systems * heavy fermions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.328, year: 2009

  3. Radial space-charge-limited electron flow in semi-insulating GaN:Fe

    Czech Academy of Sciences Publication Activity Database

    Mareš, Jiří J.; Hubík, Pavel; Krištofik, Jozef; Prušáková, Lucie; Uxa, Štěpán; Paskova, T.; Evans, K.

    2011-01-01

    Roč. 110, č. 1 (2011), 013723/1-013723/6 ISSN 0021-8979 R&D Projects: GA ČR GAP204/10/0212 Institutional research plan: CEZ:AV0Z10100521 Keywords : gallium nitride * semi-insulator * space-charge-limited current Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.168, year: 2011

  4. Various scenarios of metal-insulator transition in strongly correlated materials

    Czech Academy of Sciences Publication Activity Database

    Kuneš, Jan; Anisimov, V.I.

    2011-01-01

    Roč. 523, 8-9 (2011), 682-688 ISSN 0003-3804 R&D Projects: GA ČR GAP204/10/0284 Institutional research plan: CEZ:AV0Z10100521 Keywords : electronic correlations * metal-insulator transition * dynamical mean-field theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.841, year: 2011

  5. Metal–insulator crossover in high c cuprates: A gauge field ...

    Indian Academy of Sciences (India)

    A metal–insulator crossover appears in the experimental data for in-plane resistivity of underdoped cuprates and a range of superconducting cuprates in the presence of a strong magnetic field suppressing superconductivity. We propose an explanation for this phenomenon based on a gauge field theory approach to the t-J ...

  6. Spin gap and antiferromagnetic correlations in the kondo insulator CeNiSn

    DEFF Research Database (Denmark)

    Mason, T.E.; Aeppli, G.; Ramirez, A.P.

    1992-01-01

    Neutron scattering measurements show that the crossover (at T less than or similar to 10 K) from metallic heavy-fermion to semiconducting behavior coincides with the formation of a gap in the magnetic excitation spectrum of CeNiSn. In contrast to the simple band picture of an insulator, the gap...

  7. Spin-polarized inelastic tunneling through insulating barriers.

    Science.gov (United States)

    Lu, Y; Tran, M; Jaffrès, H; Seneor, P; Deranlot, C; Petroff, F; George, J-M; Lépine, B; Ababou, S; Jézéquel, G

    2009-05-01

    Spin-conserving hopping transport through chains of localized states has been evidenced by taking benefit of the high degree of spin-polarization of CoFeB-MgO-CoFeB magnetic tunnel junctions. In particular, our data show that relatively thick MgO barriers doped with boron favor the activation of spin-conserving inelastic channels through a chain of three localized states and leading to reduced magnetoresistance effects. We propose an extension of the Glazman-Matveev theory to the case of ferromagnetic reservoirs to account for spin-polarized inelastic tunneling through nonmagnetic localized states embedded in an insulating barrier.

  8. Samarium Hexaboride: The First True 3D Topological Insulator?

    Science.gov (United States)

    Wolgast, Steven G.

    The recent theoretical prediction of a topologically protected surface state in the mixed-valent insulator SmB6 has motivated a series of charge transport studies, which are presented here. It is first studied using a specialized configuration designed to distinguish bulk-dominated conduction from surface-dominated conduction. As the material is cooled below 4 K, it exhibits a crossover from thermally activated bulk transport to metallic surface conduction with a fully insulating bulk. The robustness and magnitude of the surface conductivity, as is manifest in the literature of SmB6, is strong evidence for the topological insulator (TI) metallic surface states predicted for this material. This resolves a decades-old puzzle surrounding the low-temperature behavior of SmB6. Next, the magnetotransport properties of the surface are investigated using a Corbino disk geometry, which can directly measure the conductivity of individual surfaces. Both (011) and (001) crystal surfaces show a strong negative magnetoresistance at all magnetic field angles, due primarily to changes in the carrier density. The low mobility value accounts for the failure so far to observe Shubnikov-de Haas oscillations below 95 T. Small variations in the mobility and temperature dependence suggest a suppression of Kondo scattering from native oxide-layer magnetic moments. At low fields, a dynamical field-sweep-rate-dependent hysteretic behavior is observed. It persists at the slowest sweep rates, and cannot be explained by quantum interference corrections; it is likely due to extrinsic effects such as the magnetocaloric effect or glassy ordering of the native oxide moments. Pulsed magnetic field measurements up to 60 T at temperatures throughout the crossover regime clearly distinguish the surface magnetoresistance from the bulk magnetoresistance. The bulk magnetoresistance is due to a reduction in the bulk gap with increasing magnetic field. Finally, small subsurface cracks formed in SmB6 via

  9. Low Permeability Polyimide Insulation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  10. Systems and Methods for Providing Insulation

    Science.gov (United States)

    Golden, Johnny L. (Inventor)

    2015-01-01

    Systems and methods provide a multi-layer insulation (MLI) that includes a plurality of sealed metalized volumes in a stacked arrangement, wherein the plurality of sealed metalized volumes encapsulate a gas therein, with the gas having one of a thermal insulating property, an acoustic insulating property, or a combination insulating property thereof. The MLI also includes at least one spacer between adjacent sealed metalized volumes of the plurality of sealed metalized volumes and a protective cover surrounding the plurality of sealed metalized volumes.

  11. Natural ageing of EPDM composite insulators

    Energy Technology Data Exchange (ETDEWEB)

    Vlastos, A.E.; Sherif, E. (Chalmers Univ. of Technology, High Voltage Engineering, S-412 96 Gothenburg (SW))

    1990-01-01

    Long-rod composite insulators, with weather sheds (sheds) made of ethylene propylene rubbers (EPDM), were exposed for many years to HVAC and HVDC under realistic conditions and natural pollution. The change of their properties with time and their aging was studied. The results show that the insulator shed material undergoes a slow degradation process and loses successively its water repelling properties which initially make the EPDM composite insulators superior to inorganic glass and porcelain insulator. The outdoor degradation of the shed material depends on the electric stress, in the environmental factors (such as pollution, rain, salt-laden fog, and UV-radiation from sun) and on the materials and fillers used in the construction of the composite insulators. A thorough macro- and microscopic study of the EPDM composite insulator sheds illustrates the differences of the surface state of EPDM insulators of different makes in which different basic material compositions and fillers are used. The poor performance of aged EPDM composite insulators compared to inorganic insulators depends on the design and on environmental factors.

  12. Characterization of Microporous Insulation, Microsil

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-06-15

    Microsil microporous insulation has been characterized by Lawrence Livermore National Laboratory for possible use in structural and thermal applications in the DPP-1 design. Qualitative test results have provided mechanical behavioral characteristics for DPP-1 design studies and focused on the material behavioral response to being crushed, cyclically loaded, and subjected to vibration for a confined material with an interference fit or a radial gap. Quantitative test results have provided data to support the DPP-1 FEA model analysis and verification and were used to determine mechanical property values for the material under a compression load. The test results are documented within this report.

  13. Optical Manipulation and Detection of Emergent Phenomena in Topological Insulators

    Energy Technology Data Exchange (ETDEWEB)

    Gedik, Nuh [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics

    2017-02-17

    The three-dimensional topological insulator (TI) is a new quantum phase of matter that exhibits quantum-Hall-like properties, even in the absence of an external magnetic field. These materials are insulators in the bulk but have a topologically protected conducting state at the surface. Charge carriers on these surface states behave like a two-dimensional gas of massless helical Dirac fermions for which the spin is ideally locked perpendicular to the momentum. The purpose of this project is to probe the unique collective electronic behaviors of topological insulators by developing and using advanced time resolved spectroscopic techniques with state-of-the-art temporal and spatial resolutions. The nature of these materials requires development of specialized ultrafast techniques (such as time resolved ARPES that also has spin detection capability, ultrafast electron diffraction that has sub-100 fs time resolution and THz magneto-spectroscopy). The focus of this report is to detail our achievements in terms of establishing state of the art experimental facilities. Below, we will describe achievements under this award for the entire duration of five years. We will focus on detailing the development of ultrafast technqiues here. The details of the science that was done with these technqiues can be found in the publications referencing this grant.

  14. Consideration and research of high voltage insulation strategy for ITER Feeder busbar joint

    International Nuclear Information System (INIS)

    Huang, Xiongyi; Song, Yuntao; Zheng, Jinxing; Yu, Xiaowu; Xiao, Weiwu; Gao, Daming; Tao, Yuming; Wang, Chunyu; Gung, Chen-yu; Clayton, Nicholas; Niu, Erwu; Chen, Yonghua; Mitcell, Neil

    2013-01-01

    Highlights: • Several rounds insulation trials for ITER Feeder joint were carried out in ASIPP. • Wet-winding, VPI were practiced and attempt for the best impregnation strategy. • Improvement of wet-winding technology with vacuum assistance was realized. • To supplement the electrical test, DR technology was explored for insulation quality inspection. -- Abstract: The ITER Feeder busbar joint is an important component which connects different sections of busbar which run from the high temperature superconducting current leads to the magnet terminals. High voltage insulated bus bar sections will be assembled onto the feeder support structure (called the containment duct), and the joints between sections will be made in situ. The high voltage insulation over the joint is the final step to complete the insulation of the whole bus bar system, and its quality is key to achieving the required electrical performance of the system. The final joint has a complex external configuration with an irregular structure in places, which makes it difficult for the application of the insulation. The limited access in the Feeder and the complex joint external structure make the implementation of the joint insulation hard to solve. The Feeder group at ASIPP has carried out significant R and D for the joint insulation, involving research on the selection of materials, the design of the insulation structure, the curing technology and the quality inspection method. After many rounds of manufacturing and testing, the insulation strategy for the Feeder joint will focus on the so-called “wet-winding” technology. Despite the fact that this process has some intrinsic disadvantages, it is more appropriate for the joint structure compared to other methods. The sub-suppliers to ASIPP have chosen this impregnation method for the feeder qualification activities based on guidance from ASIPP. This paper describes the research procedure of the ITER Feeder busbar joint insulation

  15. Peculiar ferromagnetic insulator state in the low-hole-doped manganites

    International Nuclear Information System (INIS)

    Algarabel, P.A.; Teresa, J.M. de; Blasco, J.; Ibarra, M.R.; Kapusta, Cz.; Sikora, M.; Zajac, D.; Riedi, P.C.; Ritter, C.

    2003-01-01

    In this work we show the very different nature of the ferromagnetic state of the low-hole-doped manganites with respect to other manganites showing colossal magnetoresistance. High-field measurements definitively prove the coexistence of ferromagnetic-metallic and ferromagnetic-insulating regions even when the sample is magnetically saturated, with the ground state being inhomogeneous. We have investigated La 0.9 Ca 0.1 MnO 3 as a prototype compound. A wide characterization by means of magnetic and magnetotransport measurements, neutron diffraction, small-angle neutron scattering, and nuclear magnetic resonance has allowed us to establish that the ground state is based on the existence of disordered nanometric double-exchange metallic clusters that coexist with long-range superexchange-based ferromagnetic insulating regions. Under high magnetic field the system reaches magnetization saturation by aligning the magnetic clusters and the insulating matrix, but even if they grow in size, they do not reach the percolation limit

  16. Coexistence of metallic and insulating channels in compressed YbB6

    Science.gov (United States)

    Ying, Jianjun; Tang, Lingyun; Chen, Fei; Chen, Xianhui; Struzhkin, Viktor V.

    2018-03-01

    It remains controversial whether compressed YbB6 material is a topological insulator or a Kondo topological insulator. We performed high-pressure transport, x-ray diffraction (XRD), x-ray absorption spectroscopy, and Raman-scattering measurements on YbB6 samples in search for its topological Kondo phase. Both high-pressure powder XRD and Raman measurements show no trace of structural phase transitions in YbB6 up to 50 GPa. The nonmagnetic Yb2 + gradually change to magnetic Yb3 + above 18 GPa concomitantly with the increase in resistivity. However, the transition to the insulating state occurs only around 30 GPa, accompanied by the increase in the shear stress, and anomalies in the pressure dependence of the Raman T2 g mode and in the B atomic position. The resistivity at high pressures can be described by a model taking into account coexisting insulating and metallic channels with the activation energy for the insulating channel about 30 meV. We argue that YbB6 may become a topological Kondo insulator at high pressures above 35 GPa.

  17. Quantum and classical contributions to linear magnetoresistance in topological insulator thin films

    International Nuclear Information System (INIS)

    Singh, Sourabh; Gopal, R. K.; Sarkar, Jit; Mitra, Chiranjib

    2016-01-01

    Three dimensional topological insulators possess backscattering immune relativistic Dirac fermions on their surface due to nontrivial topology of the bulk band structure. Both metallic and bulk insulating topological insulators exhibit weak-antilocalization in the low magnetic field and linear like magnetoresistance in higher fields. We explore the linear magnetoresistance in bulk insulating topological insulator Bi 2-x Sb x Te 3-y Se y thin films grown by pulsed laser deposition technique. Thin films of Bi 2-x Sb x Te 3-y Se y were found to be insulating in nature, which conclusively establishes the origin of linear magnetoresistance from surface Dirac states. The films were thoroughly characterized for their crystallinity and composition and then subjected to transport measurements. We present a careful analysis taking into considerations all the existing models of linear magnetoresistance. We comprehend that the competition between classical and quantum contributions to magnetoresistance results in linear magnetoresistance in high fields. We observe that the cross-over field decreases with increasing temperature and the physical argument for this behavior is explained.

  18. Möbius Kondo insulators

    Science.gov (United States)

    Chang, Po-Yao; Erten, Onur; Coleman, Piers

    2017-08-01

    Heavy fermion materials have recently attracted attention for their potential to combine topological protection with strongly correlated electron physics. To date, the ideas of topological protection have been restricted to the heavy fermion or `Kondo' insulators with the simplest point-group symmetries. Here we argue that the presence of nonsymmorphic crystal symmetries in many heavy fermion materials opens up a new family of topologically protected heavy electron systems. Re-examination of archival resistivity measurements in the nonsymmorphic heavy fermion insulators Ce3Bi4Pt3 and CeNiSn reveals the presence of a low-temperature conductivity plateau, making them candidate members of the new class of material. We illustrate our ideas with a specific model for CeNiSn, showing how glide symmetries generate surface states with a novel Möbius braiding that can be detected by ARPES or non-local conductivity measurements. One of the interesting effects of strong correlation is the development of partially localization or `Kondo breakdown' on the surfaces, which transforms Möbius surface states into quasi-one-dimensional conductors, with the potential for novel electronic phase transitions.

  19. Topological Insulator Nanowires and Nanoribbons

    KAUST Repository

    Kong, Desheng

    2010-01-13

    Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi2Se3 material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi2Se5 nanomaterials with a variety of morphologies. The synthesis of Bi 2Se5 nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with ∼ 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitais to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states. © 2010 American Chemical Society.

  20. Thermal insulation properties of walls

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2014-05-01

    Full Text Available Heat-protective qualities of building structures are determined by the qualities of the used materials, adequate design solutions and construction and installation work of high quality. This rule refers both to the structures made of materials similar in their structure and nature and mixed, combined by a construction system. The necessity to ecaluate thermal conductivity is important for a product and for a construction. Methods for evaluating the thermal protection of walls are based on the methods of calculation, on full-scale tests in a laboratory or on objects. At the same time there is a reason to believe that even deep and detailed calculation may cause deviation of the values from real data. Using finite difference method can improve accuracy of the results, but it doesn’t solve all problems. The article discusses new approaches to evaluating thermal insulation properties of walls. The authors propose technique of accurate measurement of thermal insulation properties in single blocks and fragments of walls and structures.

  1. Inhibition of SARS-CoV 3C-like Protease Activity by Theaflavin-3,3'-digallate (TF3

    Directory of Open Access Journals (Sweden)

    Chia-Nan Chen

    2005-01-01

    Full Text Available SARS-CoV is the causative agent of severe acute respiratory syndrome (SARS. The virally encoded 3C-like protease (3CLPro has been presumed critical for the viral replication of SARS-CoV in infected host cells. In this study, we screened a natural product library consisting of 720 compounds for inhibitory activity against 3CLPro. Two compounds in the library were found to be inhibitive: tannic acid (IC50 = 3 µM and 3-isotheaflavin-3-gallate (TF2B (IC50 = 7 µM. These two compounds belong to a group of natural polyphenols found in tea. We further investigated the 3CLPro-inhibitory activity of extracts from several different types of teas, including green tea, oolong tea, Puer tea and black tea. Our results indicated that extracts from Puer and black tea were more potent than that from green or oolong teas in their inhibitory activities against 3CLPro. Several other known compositions in teas were also evaluated for their activities in inhibiting 3CLPro. We found that caffeine, (—-epigallocatechin gallte (EGCg, epicatechin (EC, theophylline (TP, catechin (C, epicatechin gallate (ECg and epigallocatechin (EGC did not inhibit 3CLPro activity. Only theaflavin-3,3′-digallate (TF3 was found to be a 3CLPro inhibitor. This study has resulted in the identification of new compounds that are effective 3CLPro inhibitors.

  2. The twenty-four/four hour ratio (T/F ratio) of Tc-99m MDP uptake in patients with bone metastases and degenerative changes

    International Nuclear Information System (INIS)

    Israel, O.; Kleinhaus, U.; Keren, R.; Frankel, A.; Front, D.

    1984-01-01

    Normal and metastatic bone differ in their histological structure. Normal bone is mainly lamellar while metastatic bone formation is made in a large part out of new woven bone. The woven bone has a much larger surface area than the more stable lamellar bone and it is lined with metabolically active osteoblasts. The crystalline structures in the woven bone are smaller and have a larger surface area available for absorption. Uptake of bone seeking radiopharmaceuticals continues in new woven bone longer than in the lamellar bone. Bone scintigraphy was performed in 89 patients at four hours and 24 hours using a digital camera. The lesion to non lesion (L/N) ratio was determined using the camera computer. The T/F ratio was calculated: T/F=((L/N)-24)/((L/N)-4). Three groups were investigated. In 15 patients with metastatic bone carcinoma, T/F ratio was 1.46 +- 0.4. In 47 patients with degenerative joint disease the T/F ratio was 1.05 +- 0.06. In 27 patients with treated metastatic bone carcinoma the T/F ratio was 1.12 +- 0.13. The T/F ratio is significantly (p<0.001) different in patients with metastases compared to patients with benign degenerative disease. Chemotherapeutic and hormonal treatment cause significant (p<0.001) reduction in the T/F ratio. The T/F ratio may have a potential in differentiating degenerative from neoplastic diseases and in the evaluation of patients with bone metastases undergoing treatment

  3. Low-cost exterior insulation process and structure

    Science.gov (United States)

    Vohra, A.

    1999-03-02

    A low-cost exterior insulation process of stacking bags of insulating material against a wall and covering them with wire mesh and stucco provides a durable structure with good insulating value. 2 figs.

  4. Topological insulators: A romance with many dimensions

    Science.gov (United States)

    Manoharan, Hari C.

    2010-07-01

    Electric charges on the boundaries of certain insulators are programmed by topology to keep moving forward when they encounter an obstacle, rather than scattering backwards and increasing the resistance of the system. This is just one reason why topological insulators are one of the hottest topics in physics right now.

  5. Insulation materials for advanced water storages

    DEFF Research Database (Denmark)

    Schultz, Jørgen Munthe

    2005-01-01

    sections different insulation materials are described with respect to material characteristics and some comments on the easiness of application for tank insulation. The material properties listed in this paper are typical values, which gives an idea of the possibilities but in case of a specific design...

  6. Quantitative analysis of thermal insulation coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2014-01-01

    This work concerns the development of simulation tools for mapping of insulation properties of thermal insulation coatings based on selected functional filler materials. A mathematical model, which includes the underlying physics (i.e. thermal conductivity of a heterogeneous two-component coating...

  7. 49 CFR 179.201-11 - Insulation.

    Science.gov (United States)

    2010-10-01

    ...) Insulation shall be of sufficient thickness so that the thermal conductance at 60 °F. is not more than 0.075... 49 Transportation 2 2010-10-01 2010-10-01 false Insulation. 179.201-11 Section 179.201-11 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  8. Food Price Spikes, Price Insulation, and Poverty

    OpenAIRE

    Anderson, Kym; Ivanic, Maros; Martin, Will

    2013-01-01

    This paper has two purposes. It first considers the impact on world food prices of the changes in restrictions on trade in staple foods during the 2008 world food price crisis. Those changes -- reductions in import protection or increases in export restraints -- were meant to partially insulate domestic markets from the spike in international prices. The authors find that this insulation a...

  9. Thermal insulation of high temperature reactors

    International Nuclear Information System (INIS)

    Cornille, Y.

    1975-01-01

    Operating conditions of HTR thermal insulation are given and heat insulators currently developed are described (fibers kept in position by metallic structures). For future applications and higher temperatures, research is directed towards solutions using ceramics or associating fibers and ceramics [fr

  10. External insulation with cellular plastic materials

    DEFF Research Database (Denmark)

    Sørensen, Lars Schiøtt; Nielsen, Anker

    2014-01-01

    External thermal insulation composite systems (ETICS) can be used as extra insulation of existing buildings. The system can be made of cellular plastic materials or mineral wool. There is a European Technical guideline, ETAG 004, that describe the tests that shall be conducted on such systems...

  11. Failure modes and effects analysis of fusion magnet systems

    International Nuclear Information System (INIS)

    Zimmermann, M.; Kazimi, M.S.; Siu, N.O.; Thome, R.J.

    1988-12-01

    A failure modes and consequence analysis of fusion magnet system is an important contributor towards enhancing the design by improving the reliability and reducing the risk associated with the operation of magnet systems. In the first part of this study, a failure mode analysis of a superconducting magnet system is performed. Building on the functional breakdown and the fault tree analysis of the Toroidal Field (TF) coils of the Next European Torus (NET), several subsystem levels are added and an overview of potential sources of failures in a magnet system is provided. The failure analysis is extended to the Poloidal Field (PF) magnet system. Furthermore, an extensive analysis of interactions within the fusion device caused by the operation of the PF magnets is presented in the form of an Interaction Matrix. A number of these interactions may have significant consequences for the TF magnet system particularly interactions triggered by electrical failures in the PF magnet system. In the second part of this study, two basic categories of electrical failures in the PF magnet system are examined: short circuits between the terminals of external PF coils, and faults with a constant voltage applied at external PF coil terminals. An electromagnetic model of the Compact Ignition Tokamak (CIT) is used to examine the mechanical load conditions for the PF and the TF coils resulting from these fault scenarios. It is found that shorts do not pose large threats to the PF coils. Also, the type of plasma disruption has little impact on the net forces on the PF and the TF coils. 39 refs., 30 figs., 12 tabs

  12. Thermophysical investigations of nanotechnological insulation materials

    Science.gov (United States)

    Lakatos, Ákos

    2017-07-01

    Nowadays, to sufficiently reduce the heat loss through the wall structures with the so-called traditional insulations (polystyrene and fibrous slabs), huge thicknesses (20 - 25 cm) must be applied. In some cases there is no place for their applications e.g.: historical or heritage builfings, since the use of nano-insulation materials (aerogel, vacuum ceramic paints) takes place. They are said to be much more efficient insulations than the above mentioned ones, since they should be used in thinner forms. In this article the thermal insulating capability of solid brick wall covered with a silica-aerogel slab with 1.3 cm, moreover with a vacuum ceramic hollow contained paint with 2 mm thick are investigated. As well as a literature review about the thermal conductivity of nano-technological insulation materials will be given. Comparison of the atomic and thermal diffusion will be also presented.

  13. Determination of electromagnetic forces in tokamak magnets using the TORMAC Computer Program

    International Nuclear Information System (INIS)

    Johnson, N.E.

    1977-01-01

    The TORMAC Computer Program has been developed to determine electromagnetic forces for use in the structural analysis of tokamak magnet structural systems. This program has been written for use in a time-share environment on the DEC-10 computer system and prepares output force data in the form of bulk data card images as required for input by the NASTRAN Finite Element Structural Analysis System. The TORMAC Program utilizes a simplified filament method in its computational procedure. Magnets can be defined as an assemblage of inter-connected line elements representing toroidal field (TF) coils or arbitrary extra coils, or complete circular coils representing poloidal field (PF) coils. All TF coils and extra coils are developed to be directly compatible with NASTRAN finite element models. Only one TF coil need be defined with all other TF coils located internally to the program. The extra coils are located relative to the initially defined TF coil and may be used to represent discrete coils unsymmetrically placed relative to the axis of the torus. The circular PF coils must be symmetric with respect to the axis of the torus. In addition to computing electromagnetic forces at the end nodes of each TF coil and extra coil filament, electromagnetic fields are computed at each such filament as well as at a set of extra points defined in the region of each TF coil. A feature is included wherein arbitrary currents may be defined for each TF coil thus permitting the evaluation of fault conditions. Another optional feature is included to present output force data in a form compatible with the analysis of half or quarter symmetric structures. Examples are presented illustrating the use of this program during the structural analysis of tokamak devices currently being developed

  14. Mitigation of Electrothermal Instabilities with Thick Insulating Coatings

    Science.gov (United States)

    Peterson, Kyle; Awe, Thomas; Yu, Edmund; Sinars, Daniel; Cuneo, Michael

    2013-10-01

    We will show results of recent experiments on Sandia's Z facility that demonstrate a dramatic reduction in instability growth when thick insulating coatings are used to mitigate electrothermal instability growth in magnetically driven imploding liners. These results also provide further evidence that the inherent surface roughness as a result of target fabrication is not the dominant seed for the growth of Magneto-Rayleigh-Taylor (MRT) instabilities in liners with carefully machined smooth surfaces (~100 nm surface RMS or better), but rather electrothermal instabilities that form early in the electrical current pulse as Joule heating melts and vaporizes the liner surface. More importantly, these results suggest a mechanism for possibly reducing the integral MRT instability growth substantially in magnetically driven inertial confinement fusion concepts such as MagLIF. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  15. Nonlinear processes of magnons in insulating ferromagnetic materials

    International Nuclear Information System (INIS)

    Araujo, C.B. de.

    1975-04-01

    The representation of coherent states is used to investigate the excitation of magnons by 'parallel pumping', 'perpendicular pumping' and 'phonon pumping'. The stationary regime of the processes is studied with respect to the magnon population and the statistic behavior of the system below and just above the threshold. Particular attention is given to the thermodynamic and the coherence properties of the parametric states. The results show that just above the threshold the generated states become coherent. Also, it is shown that the non-linear processes have characteristics of a second-order phase transition with the pumping power as the 'reservoir variable' and the transverse dynamical magnetization as the 'order parameter'. Finally, the possibilities to extend the theory, its experimental check, and its convenience to study the other nonlinear processes of magnons and phonons in magnetic insulators are discussed. (author) [pt

  16. Preparation and Property Study of Graphene Oxide Reinforced Epoxy Resin Insulation Nanocomposites with High Heat Conductivity

    Science.gov (United States)

    Shan, Xinran; Liu, Yongchang; Wu, Zhixiong; Liu, Huiming; Zhang, Zhong; Huang, Rongjin; Huang, Chuanjun; Liu, Zheng; Li, Laifeng

    2017-02-01

    In this paper, graphene oxide reinforced epoxy resin nanocomposites were successfully prepared. Compared with unmodified epoxy resin, the heat conductivity of the graphene oxide reinforced epoxy resin nanocomposites had been improved while keeping the insulation performance. The tensile strength was investigated at both room temperature (300 K) and liquid nitrogen temperature (77 K). And the fracture surfaces were examined by scanning electron microscopy (SEM). Results showed that the materials had excellent mechanical properties, which could be advantages for the applications as insulating layer in low temperature superconducting magnets.

  17. Non-destructive qualification tests for ITER cryogenic axial insulating breaks

    International Nuclear Information System (INIS)

    Kosek, Jacek; Lopez, Roberto; Tommasini, Davide; Rodriguez-Mateos, Felix

    2014-01-01

    In the ITER superconducting magnets the dielectric separation between the CICC (Cable-In-Conduit Conductors) and the helium supply pipes is made through the so-called insulating breaks (IB). These devices shall provide the required dielectric insulation at a 30 kV level under different types of stresses and constraints: thermal, mechanical, dielectric and ionizing radiations. As part of the R and D program, the ITER Organization launched contracts with industrial companies aimed at the qualification of the manufacturing techniques. After reviewing the main functional aspects, this paper describes and discusses the protocol established for non-destructive qualification tests of the prototypes

  18. Mechanics of a composite structure of GFRP insulators and superconductors with a gap

    International Nuclear Information System (INIS)

    Tamura, H.; Imagawa, S.; Nishimura, A.

    1997-01-01

    Superconducting coils in large scale magnet applications such as the Large Helical Device (LHD) are subjected to large electromagnetic force at the interfaces between conductors and electrical insulators. The insulators do not always contact the superconductor surfaces completely. This may cause a reduction of coil rigidity. Nonlinear behavior was observed in the compressive load-displacement curves in some experiments of coil packs. The nonlinear curves were found to be well fitted by an exponential function. We considered this nonlinearity as a surface contact problem and devised some analytical models to evaluate the rigidity reduction in terms of gap length. The results of this analysis also support the exponential function

  19. Design and experiment of insulation support of 2 MeV injector

    CERN Document Server

    Wang Meng; Dai Guang Sen; Wang Jing Sheng; Xia Lian Sheng; Huang Hai Bo

    2002-01-01

    Aiming at the technical request of high power injector, the authors designed two Nylon radial graded insulation supports on the heads of cathode and anode of the existing 2 MeV injector. The experiment results showed that, on the basis of credible insulation, the supports improved the quality of coaxiality between the cathode and the anode, ameliorated the identity of the three axes of beams, magnetic field and mechanism, and settled the groundwork for advancing each technical performances of the 2 MeV injector

  20. Luminescence from metals and insulators

    International Nuclear Information System (INIS)

    Crawford, O.H.

    1985-01-01

    The term luminescence is normally applied to light emission that is not explainable by the mechanisms discussed by the other speakers in this meeting. Specifically, it is not transition radiation, surface plasmon radiation, or bremsstrahlung. One normally thinks of luminescence as arising from one-electron transitions within a medium. This talk consists of an overview of luminescence from condensed matter under irradiation by either energetic particles or photons. The author begins with organic molecules, where luminescence is best understood, and then discusses inorganic insulators and metals. Finally, the dependence of yield upon projectile species and velocity is discussed, and predictions are made concerning the relative effectiveness of electrons, protons, and hydrogen atoms in exciting luminescence