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Sample records for magnetic diffraction experiments

  1. dxtbx: the diffraction experiment toolbox.

    PubMed

    Parkhurst, James M; Brewster, Aaron S; Fuentes-Montero, Luis; Waterman, David G; Hattne, Johan; Ashton, Alun W; Echols, Nathaniel; Evans, Gwyndaf; Sauter, Nicholas K; Winter, Graeme

    2014-08-01

    Data formats for recording X-ray diffraction data continue to evolve rapidly to accommodate new detector technologies developed in response to more intense light sources. Processing the data from single-crystal X-ray diffraction experiments therefore requires the ability to read, and correctly interpret, image data and metadata from a variety of instruments employing different experimental representations. Tools that have previously been developed to address this problem have been limited either by a lack of extensibility or by inconsistent treatment of image metadata. The dxtbx software package provides a consistent interface to both image data and experimental models, while supporting a completely generic user-extensible approach to reading the data files. The library is written in a mixture of C++ and Python and is distributed as part of the cctbx under an open-source licence at http://cctbx.sourceforge.net. PMID:25242914

  2. Contributions of the electronic spin and orbital current to the CoCl{sub 4}{sup 2-} magnetic field probed in polarised neutron diffraction experiments

    SciTech Connect

    Cassam-Chenaie, Patrick; Jayatilaka, Dylan

    2012-08-14

    Polarised neutron diffraction experiments conducted at 4.2 K on Cs{sub 3}CoCl{sub 5} crystals have been analysed by using a four-dimensional model Hilbert space made of ab initio n-electron wave functions of the CoCl{sub 4}{sup 2-} molecular ion. Two spin-orbit mixing coefficients and several configuration interaction coefficients have been optimized by fitting calculated magnetic structure factors to experimental ones, to obtain the best ensemble density operator that is representable in the model space. A goodness of fit, {chi}{sup 2}, less then 1 has been obtained for the first time for the two experimental data sets available. In the present article, the optimized density operators are used to calculate the magnetic field densities that are the genuine observables probed in neutron diffraction experiments. Density maps of such observables are presented for the first time and numerical details are provided. The respective contributions of spin density and orbital current to the magnetic field density are analyzed.

  3. Recovering magnetization distributions from their noisy diffraction data

    SciTech Connect

    Loh, Ne-Te Duane; Eisebitt, Stefan; Flewett, Samuel; Elser, Veit

    2010-12-15

    We study, using simulated experiments inspired by thin-film magnetic domain patterns, the feasibility of phase retrieval in x-ray diffractive imaging in the presence of intrinsic charge scattering given only photon-shot-noise limited diffraction data. We detail a reconstruction algorithm to recover the sample's magnetization distribution under such conditions and compare its performance with that of Fourier transform holography. Concerning the design of future experiments, we also chart out the reconstruction limits of diffractive imaging when photon-shot-noise and the intensity of charge scattering noise are independently varied. This work is directly relevant to the time-resolved imaging of magnetic dynamics using coherent and ultrafast radiation from x-ray free-electron lasers and also to broader classes of diffractive imaging experiments which suffer noisy data, missing data, or both.

  4. Undergraduate Experiment with Fractal Diffraction Gratings

    ERIC Educational Resources Information Center

    Monsoriu, Juan A.; Furlan, Walter D.; Pons, Amparo; Barreiro, Juan C.; Gimenez, Marcos H.

    2011-01-01

    We present a simple diffraction experiment with fractal gratings based on the triadic Cantor set. Diffraction by fractals is proposed as a motivating strategy for students of optics in the potential applications of optical processing. Fraunhofer diffraction patterns are obtained using standard equipment present in most undergraduate physics…

  5. Anomalous Diffraction in Cold Magnetized Plasma.

    PubMed

    Abelson, Z; Gad, R; Bar-Ad, S; Fisher, A

    2015-10-01

    Cold magnetized plasma possesses an anisotropic permittivity tensor with a unique dispersion relation that for adequate electron density and magnetic field results in anomalous diffraction of a right-hand circularly polarized beam. In this work, we demonstrate experimentally anomalous diffraction of a microwave beam in plasma. Additionally, decreasing the electron density enables observation of the transition of the material from a hyperbolic to a standard material. Manipulation of the control parameters will enable plasma to serve as a reconfigurable metamaterial-like medium. PMID:26551813

  6. Diffraction experiments with infrared remote controls

    NASA Astrophysics Data System (ADS)

    Kuhn, Jochen; Vogt, Patrik

    2012-02-01

    In this paper we describe an experiment in which radiation emitted by an infrared remote control is passed through a diffraction grating. An image of the diffraction pattern is captured using a cell phone camera and then used to determine the wavelength of the radiation.

  7. An Improved Diffraction Grating Spectroscope Experiment.

    ERIC Educational Resources Information Center

    Scherzer, Robert

    1995-01-01

    Discusses problems associated with standard diffraction grating experiments involving a diffraction grating, a straight meter stick, and a slit. Describes the use of a new spectroscope to overcome these problems using a curved scale to simplify calculations and help students obtain results from simple and straightforward measurements, thus giving…

  8. X-ray diffraction microscopy of magnetic structures.

    PubMed

    Turner, Joshua J; Huang, Xiaojing; Krupin, Oleg; Seu, Keoki A; Parks, Daniel; Kevan, Stephen; Lima, Enju; Kisslinger, Kim; McNulty, Ian; Gambino, Richard; Mangin, Stephane; Roy, Sujoy; Fischer, Peter

    2011-07-15

    We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L3 edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.

  9. X-Ray Diffraction Microscopy of Magnetic Structures

    SciTech Connect

    Turner, J.; Lima, E.; Huang, X.; Krupin, O.; Seu, K.; Parks, D.; Kevan, S.; Kisslinger, K.; McNulty, I.; Gambino, R.; Mangin, S.; Roy, S. and Fischer, P.

    2011-07-14

    We report the first proof-of-principle experiment of iterative phase retrieval from magnetic x-ray diffraction. By using the resonant x-ray excitation process and coherent x-ray scattering, we show that linearly polarized soft x rays can be used to image both the amplitude and the phase of magnetic domain structures. We recovered the magnetic structure of an amorphous terbium-cobalt thin film with a spatial resolution of about 75 nm at the Co L{sub 3} edge at 778 eV. In comparison with soft x-ray microscopy images recorded with Fresnel zone plate optics at better than 25 nm spatial resolution, we find qualitative agreement in the observed magnetic structure.

  10. Data Exploration Toolkit for serial diffraction experiments

    DOE PAGES

    Zeldin, Oliver B.; Brewster, Aaron S.; Hattne, Johan; Uervirojnangkoorn, Monarin; Lyubimov, Artem Y.; Zhou, Qiangjun; Zhao, Minglei; Weis, William I.; Sauter, Nicholas K.; Brunger, Axel T.

    2015-01-23

    Ultrafast diffraction at X-ray free-electron lasers (XFELs) has the potential to yield new insights into important biological systems that produce radiation-sensitive crystals. An unavoidable feature of the 'diffraction before destruction' nature of these experiments is that images are obtained from many distinct crystals and/or different regions of the same crystal. Combined with other sources of XFEL shot-to-shot variation, this introduces significant heterogeneity into the diffraction data, complicating processing and interpretation. To enable researchers to get the most from their collected data, a toolkit is presented that provides insights into the quality of, and the variation present in, serial crystallography datamore » sets. These tools operate on the unmerged, partial intensity integration results from many individual crystals, and can be used on two levels: firstly to guide the experimental strategy during data collection, and secondly to help users make informed choices during data processing.« less

  11. Data Exploration Toolkit for serial diffraction experiments

    PubMed Central

    Zeldin, Oliver B.; Brewster, Aaron S.; Hattne, Johan; Uervirojnangkoorn, Monarin; Lyubimov, Artem Y.; Zhou, Qiangjun; Zhao, Minglei; Weis, William I.; Sauter, Nicholas K.; Brunger, Axel T.

    2015-01-01

    Ultrafast diffraction at X-ray free-electron lasers (XFELs) has the potential to yield new insights into important biological systems that produce radiation-sensitive crystals. An unavoidable feature of the ‘diffraction before destruction’ nature of these experiments is that images are obtained from many distinct crystals and/or different regions of the same crystal. Combined with other sources of XFEL shot-to-shot variation, this introduces significant heterogeneity into the diffraction data, complicating processing and interpretation. To enable researchers to get the most from their collected data, a toolkit is presented that provides insights into the quality of, and the variation present in, serial crystallography data sets. These tools operate on the unmerged, partial intensity integration results from many individual crystals, and can be used on two levels: firstly to guide the experimental strategy during data collection, and secondly to help users make informed choices during data processing. PMID:25664746

  12. Effect of recording condition on the diffraction efficiency of magnetic hologram with magnetic garnet films

    SciTech Connect

    Nakamura, Yuichi Takagi, Hiroyuki; Lim, Pang Boey; Inoue, Mitsuteru

    2014-09-14

    A holographic memory has been attracting attention as recording media with high recording density and high data transfer rate. We have studied the magnetic garnets as a rewritable and long life media for magnetic holography. However, since the signal intensity of reconstructed image was relatively low, the effects of recording conditions on the diffraction efficiency of magnetic hologram were investigated with experiments and the numerical simulation using COMSOL multi-physics. The diffraction efficiency tends to decrease as increasing the spatial frequency, and the use of short pulse laser with the pulse width of 50 ps was found to be effective to achieve high diffraction efficiency. This suggests that the formation of clear magnetic fringe similar to interference pattern can be obtained by the use of short pulse laser since undesirable heat diffusion during radiation does not occur. On the other hand, the diffraction efficiency increased as increasing the film thickness up to 3.1 μm but was saturated in the garnet film thicker than 3.1 μm in the case of spatial frequency of 1500 line pair/mm. The numerical simulation showed that the effective depth of magnetic fringe was limited about 1.8 μm irrespective of the garnet film thickness because the fringes were connected by thermal diffusion near the surface of the film, and the effective depth is limited due to this connection of the magnetic fringe. Avoiding this fringe connection, much higher diffraction efficiency will be achieved.

  13. Data Exploration Toolkit for serial diffraction experiments

    SciTech Connect

    Zeldin, Oliver B.; Brewster, Aaron S.; Hattne, Johan; Uervirojnangkoorn, Monarin; Lyubimov, Artem Y.; Zhou, Qiangjun; Zhao, Minglei; Weis, William I.; Sauter, Nicholas K.; Brunger, Axel T.

    2015-02-01

    This paper describes a set of tools allowing experimentalists insight into the variation present within large serial data sets. Ultrafast diffraction at X-ray free-electron lasers (XFELs) has the potential to yield new insights into important biological systems that produce radiation-sensitive crystals. An unavoidable feature of the ‘diffraction before destruction’ nature of these experiments is that images are obtained from many distinct crystals and/or different regions of the same crystal. Combined with other sources of XFEL shot-to-shot variation, this introduces significant heterogeneity into the diffraction data, complicating processing and interpretation. To enable researchers to get the most from their collected data, a toolkit is presented that provides insights into the quality of, and the variation present in, serial crystallography data sets. These tools operate on the unmerged, partial intensity integration results from many individual crystals, and can be used on two levels: firstly to guide the experimental strategy during data collection, and secondly to help users make informed choices during data processing.

  14. Diffraction patterns in ferrofluids: Effect of magnetic field and gravity

    NASA Astrophysics Data System (ADS)

    Radha, S.; Mohan, Shalini; Pai, Chintamani

    2014-09-01

    In this paper, we report the experimental observation of diffraction patterns in a ferrofluid comprising of Fe3O4 nanoparticles in hexane by a 10 mW He-Ne laser beam. An external dc magnetic field (0-2 kG) was applied perpendicular to the beam. The diffraction pattern showed a variation at different depths of the sample in both zero and applied magnetic field. The patterns also exhibit a change in shape and size as the external field is varied. This effect arises due to thermally induced self-diffraction under the influence of gravity and external magnetic field.

  15. Synchrotron X-ray Powder Diffraction Studies in Pulsed Magnetic Fields

    SciTech Connect

    Detlefs, C.; Frings, P.; Duc, F.; Nardone, M.; Billette, J.; Zitouni, A.; Rikken, G. L. J. A.; Vanacken, J.; Lorenzo, J. E.; Bras, W.

    2007-01-19

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110kJ to the magnet coil, which was sufficient to generate peak fields of 30T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8K and 300K.

  16. Electron Diffraction Experiments using Laser Plasma Electrons

    SciTech Connect

    Fill, E E; Trushin, S; Tommasini, R; Bruch, R

    2005-09-07

    We demonstrate that electrons emitted from a laser plasma can be used to generate diffraction patterns in reflection and transmission. The electrons are emitted in the direction of laser polarization with energies up to 100 keV. The broad electron energy spectrum makes possible the generation of a ''streaked'' diffraction pattern which allows recording fast processes in a single run.

  17. Synchrotron x-ray powder diffraction studies in pulsed magnetic fields

    SciTech Connect

    Frings, P.; Vanacken, J.; Detlefs, C.; Duc, F.; Lorenzo, J. E.; Nardone, M.; Billette, J.; Zitouni, A.; Bras, W.; Rikken, G. L. J. A.

    2006-06-15

    X-ray powder diffraction experiments under pulsed magnetic fields were carried out at the DUBBLE beamline (BM26B) at the ESRF. A mobile generator delivered 110 kJ to the magnet coil, which was sufficient to generate peak fields of 30 T. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 8 and 300 K. Powder diffraction patterns of several samples were recorded using 21 keV monochromatic x-rays and an on-line image plate detector. Here we present the first results on the suppression of the Jahn-Teller structural distortion in TbVO{sub 4} by magnetic field. These data clearly demonstrate the feasibility of x-ray powder diffraction experiments under pulsed magnetic fields with relatively inexpensive instrumentation.

  18. Experiments on Magnetic Deflagration

    NASA Astrophysics Data System (ADS)

    Tejada, Javier

    2011-03-01

    Magnetic deflagration was first observed in molecular magnets [1,2] and then in glassy magnetic materials like manganites [3,4] and intermetallic systems like Gd 5 Ge 4. The role of the chemical energy is played by the magnetic energy of the material. In the case of a molecular magnet, this is Zeeman energy, while in manganites and Gd 5 Ge 4 the free energy is a combination of the Zeeman energy and the energy of the metastable magnetic phase. In molecular magnets both the ignition process and the speed of the flame are assisted by quantum spin reversal. There also exists some evidence of the transition from deflagration to detonation. Various experimental techniques have been used to detect the speed of the magnetic flame. They include SQUID magnetometry, Hall bars and coils. Magnetic deflagration has been ignited by local heating, application of external fields, by surface acoustic waves and microwaves. High frequency EPR measurements of the population of spin levels permitted observation of magnetic deflagration in real time. The talk will review these experiments and their interpretation.

  19. Detection of electron magnetic circular dichroism signals under zone axial diffraction geometry.

    PubMed

    Song, Dongsheng; Rusz, Jan; Cai, Jianwang; Zhu, Jing

    2016-10-01

    EMCD (electron magnetic circular dichroism) technique provides us a new opportunity to explore magnetic properties in the transmission electron microscope. However, specific diffraction geometry is the major limitation. Only the two-beam and three-beam case are demonstrated in the experiments until now. Here, we present the more general case of zone axial (ZA) diffraction geometry through which the EMCD signals can be detected even with the very strong sensitivity to dynamical diffraction conditions. Our detailed calculations and well-controlled diffraction conditions lead to experiments in agreement with theory. The effect of dynamical diffraction conditions on EMCD signals are discussed both in theory and experiments. Moreover, with the detailed analysis of dynamical diffraction effects, we experimentally obtain the separate EMCD signals for each crystallographic site in Y3Fe5O12, which is also applicable for other materials and cannot be achieved by site-specific EMCD and XMCD technique directly. Our work extends application of more general diffraction geometries and will further promote the development of EMCD technique. PMID:27448200

  20. Magnetic structures of actinide materials by pulsed neutron diffraction

    SciTech Connect

    Lawson, A.C.; Goldstone, J.A.; Huber, J.G.; Giorgi, A.L.; Conant, J.W.; Severing, A.; Cort, B.; Robinson, R.A.

    1990-01-01

    We describe some attempts to observe magnetic structure in various actinide (5f-electron) materials. Our experimental technique is neutron powder diffraction as practiced at a spallation (pulsed) neutron source. We will discuss our investigations of {alpha}-Pu, {delta}-Pu, {alpha}-UD{sub 3} and {beta}-UD{sub 3}. {beta}-UD{sub 3} is a simple ferromagnet: surprisingly, the moments on the two non-equivalent uranium atoms are the same within experimental error. {alpha}-UD{sub 3}, {alpha}-Pu and {delta}-Pu are non-magnetic, within the limits of our observations. Our work with pulsed neutron diffraction shows that it is a useful technique for research on magnetic materials.

  1. NOTES ON EXPERIMENTS: Diffraction demonstration on television

    NASA Astrophysics Data System (ADS)

    Kruglak, Haym

    1989-11-01

    The experimental arrangement of a previous note (see ibid., vol.23, p.306 (1988) and see Phys. Teach. vol.26, p.157 (1988)) can be used for displaying diffraction patterns on a TV monitor. The relevant apparatus is shown and latex microspheres, available from scientific supply houses, are projected with a microscope onto a TV monitor. One drop of the latex concentrate is diluted with 25-50 ml of H2O. The cavity of a depression slide is filled with the suspension. A cover glass is placed over the cavity, the excess liquid wiped off and the edges of the cover seated with nail polish. The lens of the TV camera is removed and replaced with a 10-15 cm metal or cardboard tube. The eyepiece of the microscope is also removed. With a 20× objective and a 50-60 cm distance between the bottom of the camera and the microscope stage, the image diameters of the microspheres on the monitor screen are 1-2 cm in diameter. The Fresnel diffraction bands around 1.1 μm latex microspheres are shown.

  2. The Heisenberg Uncertainty Principle Demonstrated with An Electron Diffraction Experiment

    ERIC Educational Resources Information Center

    Matteucci, Giorgio; Ferrari, Loris; Migliori, Andrea

    2010-01-01

    An experiment analogous to the classical diffraction of light from a circular aperture has been realized with electrons. The results are used to introduce undergraduate students to the wave behaviour of electrons. The diffraction fringes produced by the circular aperture are compared to those predicted by quantum mechanics and are exploited to…

  3. Measuring Slit Width and Separation in a Diffraction Experiment

    ERIC Educational Resources Information Center

    Gan, K. K.; Law, A. T.

    2009-01-01

    We present a procedure for measuring slit width and separation in single- and double-slit diffraction experiments. Intensity spectra of diffracted laser light are measured with an optical sensor (PIN diode). Slit widths and separations are extracted by fitting to the measured spectra. We present a simple fitting procedure to account for the…

  4. The Newton two-knife experiment: Intricacies of wedge diffraction

    NASA Astrophysics Data System (ADS)

    Silverman, M. P.; Strange, Wayne

    1996-06-01

    About a century before Young's celebrated two-slit experiment, Isaac Newton quantitatively investigated the diffraction of light from a wedge aperture, but failed to understand the implications of his findings. We have reexamined this unusual system theoretically within the framework of the Fresnel-Kirchhoff scalar diffraction theory, and experimentally using a laser light source with pinhole spatial filter and CCD camera. Both the far-field shadow region and near-field directly illuminated region reveal aesthetically striking images that are deducible from the mathematical analysis, but whose interpretation is subtle and best elucidated by an alternative and less widely known perspective of diffraction.

  5. Optical Tweezers for Sample Fixing in Micro-Diffraction Experiments

    SciTech Connect

    Amenitsch, H.; Rappolt, M.; Sartori, B.; Laggner, P.; Cojoc, D.; Ferrari, E.; Garbin, V.; Di Fabrizio, E.; Burghammer, M.; Riekel, Ch.

    2007-01-19

    In order to manipulate, characterize and measure the micro-diffraction of individual structural elements down to single phospholipid liposomes we have been using optical tweezers (OT) combined with an imaging microscope. We were able to install the OT system at the microfocus beamline ID13 at the ESRF and trap clusters of about 50 multi-lamellar liposomes (< 10 {mu}m large cluster). Further we have performed a scanning diffraction experiment with a 1 micrometer beam to demonstrate the fixing capabilities and to confirm the size of the liposome cluster by X-ray diffraction.

  6. Magnetic-Field Induced Diffraction Patterns from Ferrofluids

    NASA Astrophysics Data System (ADS)

    Rablau, Corneliu; Vaishnava, Prem; Lawes, Gavin; Naik, Ratna

    2011-04-01

    Ferrofluids are stable colloidal suspensions of superparamagnetic nanoparticles in a carrier liquid. We report studies of magneto-optic properties of two ferrofluid systems consisting of tetramethyl-ammonium-hydroxide (TMAH)-coated and of dextran-coated Fe3O4 nanoparticles of nominal sizes of 6 nm and 12 nm respectively suspended in water. Both samples showed superparamagnetic behavior. The static and time-dependent DC-magnetic-field-induced light scattering patterns produced by two orthogonal He-Ne laser beams passing through the ferrofluid samples revealed significant different optical signatures for the two surfactants. Notably, in contrast to the linear diffraction pattern produced by TMAH-coated nanoparticles, a circular diffraction pattern is reported -- for the first time -- in the dextran-coated ferrofluid.

  7. MOKE Diffraction Study of Magnetic Dot and Antidot Arrays.

    NASA Astrophysics Data System (ADS)

    Grimsditch, Marcos

    2003-03-01

    A beam of visible light, incident on a particle array with a submicron period, is diffracted. Extending conventional Magneto Optic Kerr Effect (MOKE) techniques to include the diffracted beams leads to a variety of 'hysteresis' loops. From these loops we show that it is possible to obtain information on the magnetic structure within a unit cell of the array. A brief review of the experimental technique, the theoretical interpretation of the results, and a brief summary of our earlier results on vortices in circular disks [1] and coherent domain formation in antidot arrays [2] will be given. The D-MOKE results from square Permalloy rings will then be presented and compared with micromagnetic simulations. Our results show that magnetization reversal in these ring structures, which is expected to be a jump between two onion states, actually occurs via intermediate, metastable states. For different directions of the applied field these intermediate states are a vortex state or a horseshoe state. A suitable field history allows these states to be quenched and observed using Magnetic Force Microscopy. Work at ANL supported by the US DOE BES Mater. Sci. under contract # W-31-109-ENG-38. [1] M. Grimsditch et al, Phys. Rev. B 65, 172419 (2002) [2] I. Guedes et al, Phys, Rev. B 66, 014434 (2002)

  8. Maximizing Macromolecule Crystal Size for Neutron Diffraction Experiments

    NASA Technical Reports Server (NTRS)

    Judge, R. A.; Kephart, R.; Leardi, R.; Myles, D. A.; Snell, E. H.; vanderWoerd, M.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    A challenge in neutron diffraction experiments is growing large (greater than 1 cu mm) macromolecule crystals. In taking up this challenge we have used statistical experiment design techniques to quickly identify crystallization conditions under which the largest crystals grow. These techniques provide the maximum information for minimal experimental effort, allowing optimal screening of crystallization variables in a simple experimental matrix, using the minimum amount of sample. Analysis of the results quickly tells the investigator what conditions are the most important for the crystallization. These can then be used to maximize the crystallization results in terms of reducing crystal numbers and providing large crystals of suitable habit. We have used these techniques to grow large crystals of Glucose isomerase. Glucose isomerase is an industrial enzyme used extensively in the food industry for the conversion of glucose to fructose. The aim of this study is the elucidation of the enzymatic mechanism at the molecular level. The accurate determination of hydrogen positions, which is critical for this, is a requirement that neutron diffraction is uniquely suited for. Preliminary neutron diffraction experiments with these crystals conducted at the Institute Laue-Langevin (Grenoble, France) reveal diffraction to beyond 2.5 angstrom. Macromolecular crystal growth is a process involving many parameters, and statistical experimental design is naturally suited to this field. These techniques are sample independent and provide an experimental strategy to maximize crystal volume and habit for neutron diffraction studies.

  9. Experiments on Magnetic Materials

    ERIC Educational Resources Information Center

    Schneider, C. S.; Ertel, John P.

    1978-01-01

    Describes the construction and use of a simple apparatus to measure the magnetization density and magnetic susceptibility of ferromagnetic, paramagnetic, and the diamagnetic solids and liquids. (Author/GA)

  10. Magnetic neutron diffraction and pressure studies on CeRuSn

    NASA Astrophysics Data System (ADS)

    Hartwig, Steffen; Prokeš, Karel; Huang, Yingkai; Pöttgen, Rainer

    2015-03-01

    We have determined the influence of magnetic fields on the crystal and magnetic structures of CeRuSn using single crystal neutron diffraction and susceptibility measurements at various pressures up to 7.4 kbar and temperatures down to 1.6 K. CeRuSn adopts below 160 K an incommensurately modulated crystal structure. It orders antiferromagnetically below TN=2.8 K in an incommensurate manner as well. This Néel-temperature is pressure independent up to 7.4 kbar. The neutron diffraction experiments detected a magnetic modulation vector qmag = (0, 0, 0.175), however, it is commensurate with the incommensurate crystal structure with qnuc = (0, 0, 0.35). At 0.6 T as well as at 0.9 T metamagnetic transitions have been observed via magnetic property measurements. The magnetic field of 0.9 T applied along the c-axis suppresses the magnetic reflections. The moments align ferromagnetically along the modulated crystal structure. Up to 3 T no change of the wavelength of the crystal structure modulations could be detected.

  11. Photoelectron diffraction of magnetic ultrathin films: Fe/Cu(001)

    SciTech Connect

    Tobin, J.G. ); Wagner, M.K. . Dept. of Chemistry); Guo, X.Q.; Tong, S.Y. . Dept. of Physics)

    1991-01-03

    The preliminary results of an ongoing investigation of Fe/Cu(001) are presented here. Energy dependent photoelectron diffraction, including the spin-dependent variant using the multiplet split Fe3s state, is being used to investigate the nanoscale structures formed by near-monolayer deposits of Fe onto Cu(001). Core-level photoemission from the Fe3p and Fe3s states has been generated using synchrotron radiation as the tunable excitation source. Tentatively, a comparison of the experimental Fe3p cross section measurements with multiple scattering calculations indicates that the Fe is in a fourfold hollow site with a spacing of 3.6{Angstrom} between it and the atom directly beneath it, in the third layer. This is consistent with an FCC structure. The possibility of utilizing spin-dependent photoelectron diffraction to investigate magnetic ultrathin films will be demonstrated, using our preliminary spectra of the multiplet-split Fe3s os near-monolayer Fe/Cu(001). 18 refs., 10 figs.

  12. Magnetic line source diffraction by a perfect electromagnetic conductor (PEMC) step

    NASA Astrophysics Data System (ADS)

    Ahmed, Saeed

    2015-02-01

    In this paper, an analytic theory for the magnetic line source diffraction by a perfect electromagnetic conductor (PEMC) step is developed. Using the duality transformation, introduced by Lindell and Sihvola, transformations have been made from the diffraction of a magnetic line source by a perfect electric conductor (PEC) step. As an application, plane wave diffracted from a planar interface of air and PEMC media is studied. PEC and PMC are the limiting cases, while there is no cross-polarized component.

  13. Sacrificial tamper slows down sample explosion in FLASH diffraction experiments.

    PubMed

    Hau-Riege, Stefan P; Boutet, Sébastien; Barty, Anton; Bajt, Sasa; Bogan, Michael J; Frank, Matthias; Andreasson, Jakob; Iwan, Bianca; Seibert, M Marvin; Hajdu, Janos; Sakdinawat, Anne; Schulz, Joachim; Treusch, Rolf; Chapman, Henry N

    2010-02-12

    Intense and ultrashort x-ray pulses from free-electron lasers open up the possibility for near-atomic resolution imaging without the need for crystallization. Such experiments require high photon fluences and pulses shorter than the time to destroy the sample. We describe results with a new femtosecond pump-probe diffraction technique employing coherent 0.1 keV x rays from the FLASH soft x-ray free-electron laser. We show that the lifetime of a nanostructured sample can be extended to several picoseconds by a tamper layer to dampen and quench the sample explosion, making <1 nm resolution imaging feasible.

  14. Sacrificial Tamper Slows Down Sample Explosion in FLASH Diffraction Experiments

    NASA Astrophysics Data System (ADS)

    Hau-Riege, Stefan P.; Boutet, Sébastien; Barty, Anton; Bajt, Saša; Bogan, Michael J.; Frank, Matthias; Andreasson, Jakob; Iwan, Bianca; Seibert, M. Marvin; Hajdu, Janos; Sakdinawat, Anne; Schulz, Joachim; Treusch, Rolf; Chapman, Henry N.

    2010-02-01

    Intense and ultrashort x-ray pulses from free-electron lasers open up the possibility for near-atomic resolution imaging without the need for crystallization. Such experiments require high photon fluences and pulses shorter than the time to destroy the sample. We describe results with a new femtosecond pump-probe diffraction technique employing coherent 0.1 keV x rays from the FLASH soft x-ray free-electron laser. We show that the lifetime of a nanostructured sample can be extended to several picoseconds by a tamper layer to dampen and quench the sample explosion, making <1nm resolution imaging feasible.

  15. Sacrificial tamper slows down sample explosion in FLASH diffraction experiments.

    PubMed

    Hau-Riege, Stefan P; Boutet, Sébastien; Barty, Anton; Bajt, Sasa; Bogan, Michael J; Frank, Matthias; Andreasson, Jakob; Iwan, Bianca; Seibert, M Marvin; Hajdu, Janos; Sakdinawat, Anne; Schulz, Joachim; Treusch, Rolf; Chapman, Henry N

    2010-02-12

    Intense and ultrashort x-ray pulses from free-electron lasers open up the possibility for near-atomic resolution imaging without the need for crystallization. Such experiments require high photon fluences and pulses shorter than the time to destroy the sample. We describe results with a new femtosecond pump-probe diffraction technique employing coherent 0.1 keV x rays from the FLASH soft x-ray free-electron laser. We show that the lifetime of a nanostructured sample can be extended to several picoseconds by a tamper layer to dampen and quench the sample explosion, making <1 nm resolution imaging feasible. PMID:20366823

  16. Upgrade of X-ray Magnetic Diffraction Experimental System and Its Application to Ferromagnetic Material

    SciTech Connect

    Suzuki, Kosuke; Tsuji, Naruki; Akiyama, Hiromitu; Ito, Masahisa; Kitani, Kensuke; Adachi, Hiromichi; Kawata, Hiroshi

    2007-01-19

    We have performed X-ray magnetic diffraction (XMD) experiment of ferromagnets at the Photon Factory (PF) of the High Energy Accelerator Research Organization (KEK) in Tsukuba. In this study, we have upgraded the XMD experimental system in order to apply this method to as many samples as possible. Upgrade was made for (1) the X-ray counting system and related measurement program, (2) the electromagnet, and (3) the refrigerator. The performance of the system was enhanced so that (1) the counting rate capability was improved from 104cps to 105cps, (2) the maximum magnetic field was increased from 0.85T to 2.15T, and (3) the lowest sample temperature was reduced from 15K to 5K. The new system was applied to an orbital ordering compound of YTiO3, and we obtained spin magnetic form factor for the reflection plane (010) perpendicular to the b axis. The magnetic field of 2T was needed to saturate the magnetization of YTiO3 along the b axis. These are the first data with the magnetization of YTiO3 saturated along the b axis by the XMD.

  17. Polar Magnetic Field Experiment

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1999-01-01

    This grant covers the initial data reduction and analysis of the magnetic field measurements of the Polar spacecraft. At this writing data for the first three years of the mission have been processed and deposited in the key parameter database. These data are also available in a variety of time resolutions and coordinate systems via a webserver at UCLA that provides both plots and digital data. The flight software has twice been reprogrammed: once to remove a glitch in the data where there were rare collisions between commands in the central processing unit and once to provide burst mode data at 100 samples per second on a regular basis. The instrument continues to function as described in the instrument paper (1.1 in the bibliography attached below). The early observations were compared with observations on the same field lines at lower altitude. The polar magnetic measurements also proved to be most useful for testing the accuracy of MHD models. WE also made important contributions to study of waves and turbulence.

  18. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Parsons, R.; Yanai, T.; Kishimoto, H.; Kato, A.; Ohnuma, M.; Suzuki, K.

    2015-05-01

    In order to better understand the origin of field-induced anisotropy (Ku) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe94-xNb6Bx (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λs) of nanocrystalline Fe94-xNb6Bx was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λs values for the bcc-Fe nanocrystallites (-5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured Ku values (˜100 J/m3) was estimated via the inverse magnetostrictive effect using the measured λs values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce Ku under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced Ku cannot be explained through the magnetoelastic effect.

  19. Magnetic Barkhausen Noise and Neutron Diffraction Techniques for the Study of Intergranular Residual Strains in Mild Steel

    SciTech Connect

    Hutanu, Roxana; Clapham, Lynann; Rogge, Ronald

    2004-02-26

    Intergranular residual stresses (IS) are microscopic residual stresses which have been found to accumulate along the <100> direction in steels. The <100> direction is also the magnetic easy axis direction in steel. This work involved Magnetic Barkhausen Noise (MBN) studies on steel samples, deformed uniaxially to increasing levels of strain. The MBN results indicated that a bulk magnetic easy axis was produced by the deformation process, and neutron diffraction experiments showed that this easy axis was correlated with the tensile strain in grains oriented in the <100> direction.

  20. Mössbauer, magnetization and X-ray diffraction characterization methods for iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Gabbasov, Raul; Polikarpov, Michael; Cherepanov, Valery; Chuev, Michael; Mischenko, Iliya; Lomov, Andrey; Wang, Andrew; Panchenko, Vladislav

    2015-04-01

    Water soluble magnetite iron oxide nanoparticles with oleic polymer coating and average diameters in the range of 5-25 nm, previously determined by TEM, were characterized using Mössbauer, magnetization and X-ray diffraction measurements. Comparative analysis of the results demonstrated a large diversity of magnetic relaxation regimes. Analysis showed the presence of an additional impurity component in the 25 nm nanoparticles, with principally different magnetic nature at the magnetite core. In some cases, X-ray diffraction measurements were unable to estimate the size of the magnetic core and Mössbauer data were necessary for the correct interpretation of the experimental results.

  1. Correlating sampling and intensity statistics in nanoparticle diffraction experiments

    DOE PAGES

    Öztürk, Hande; Yan, Hanfei; Hill, John P.; Noyan, I. Cevdet

    2015-07-28

    It is shown in a previous article [Öztürk, Yan, Hill & Noyan (2014).J. Appl. Cryst.47, 1016–1025] that the sampling statistics of diffracting particle populations within a polycrystalline ensemble depended on the size of the constituent crystallites: broad X-ray peak breadths enabled some nano-sized particles to contribute more than one diffraction spot to Debye–Scherrer rings. Here it is shown that the equations proposed by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] (AKK) to link diffracting particle and diffracted intensity statistics are not applicable if the constituent crystallites of the powder are below 10 nm. In this size range, (i) themore » one-to-one correspondence between diffracting particles and Laue spots assumed in the AKK analysis is not satisfied, and (ii) the crystallographic correlation between Laue spots originating from the same grain invalidates the assumption that all diffracting plane normals are randomly oriented and uncorrelated. Such correlation produces unexpected results in the selection of diffracting grains. For example, three or more Laue spots from a given grain for a particular reflection can only be observed at certain wavelengths. In addition, correcting the diffracted intensity values by the traditional Lorentz term, 1/cos θ, to compensate for the variation of particles sampled within a reflection band does not maintain fidelity to the number of poles contributing to the diffracted signal. A new term, cos θB/cos θ, corrects this problem.« less

  2. Correlating Sampling and Intensity Statistics in Nanoparticle Diffraction Experiments

    SciTech Connect

    Ozturk, Hande; Yan, Hanfei; Hill, John P.; Noyan, I. Cevdet

    2015-08-01

    In this article, [Öztürk, Yan, Hill & Noyan (2014). J. Appl. Cryst. 47, 1016-1025] it was shown that the sampling statistics of diffracting particle populations within a polycrystalline ensemble depended on the size of the constituent crystallites: broad X-ray peak breadths enabled some nano-sized particles to contribute more than one diffraction spot to Debye-Scherrer rings. Here it is shown that the equations proposed by Alexander, Klug & Kummer [J. Appl. Phys. (1948), 19, 742-753] (AKK) to link diffracting particle and diffracted intensity statistics are not applicable if the constituent crystallites of the powder are below 10 nm. In this size range, (i) the one-to-one correspondence between diffracting particles and Laue spots assumed in the AKK analysis is not satisfied, and (ii) the crystallographic correlation between Laue spots originating from the same grain invalidates the assumption that all diffracting plane normals are randomly oriented and uncorrelated. Such correlation produces unexpected results in the selection of diffracting grains. Three or more Laue spots from a given grain for a particular reflection can only be observed at certain wavelengths. In addition, correcting the diffracted intensity values by the traditional Lorentz term, 1/cos [theta], to compensate for the variation of particles sampled within a reflection band does not maintain fidelity to the number of poles contributing to the diffracted signal. A new term, cos [theta]B/cos [theta], corrects this problem.

  3. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    SciTech Connect

    Parsons, R. Suzuki, K.; Yanai, T.; Kishimoto, H.; Kato, A.; Ohnuma, M.

    2015-05-07

    In order to better understand the origin of field-induced anisotropy (K{sub u}) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λ{sub s}) of nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λ{sub s} values for the bcc-Fe nanocrystallites (−5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured K{sub u} values (∼100 J/m{sup 3}) was estimated via the inverse magnetostrictive effect using the measured λ{sub s} values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce K{sub u} under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced K{sub u} cannot be explained through the magnetoelastic effect.

  4. Correlating sampling and intensity statistics in nanoparticle diffraction experiments

    SciTech Connect

    Öztürk, Hande; Yan, Hanfei; Hill, John P.; Noyan, I. Cevdet

    2015-07-28

    It is shown in a previous article [Öztürk, Yan, Hill & Noyan (2014).J. Appl. Cryst.47, 1016–1025] that the sampling statistics of diffracting particle populations within a polycrystalline ensemble depended on the size of the constituent crystallites: broad X-ray peak breadths enabled some nano-sized particles to contribute more than one diffraction spot to Debye–Scherrer rings. Here it is shown that the equations proposed by Alexander, Klug & Kummer [J. Appl. Phys.(1948),19, 742–753] (AKK) to link diffracting particle and diffracted intensity statistics are not applicable if the constituent crystallites of the powder are below 10 nm. In this size range, (i) the one-to-one correspondence between diffracting particles and Laue spots assumed in the AKK analysis is not satisfied, and (ii) the crystallographic correlation between Laue spots originating from the same grain invalidates the assumption that all diffracting plane normals are randomly oriented and uncorrelated. Such correlation produces unexpected results in the selection of diffracting grains. For example, three or more Laue spots from a given grain for a particular reflection can only be observed at certain wavelengths. In addition, correcting the diffracted intensity values by the traditional Lorentz term, 1/cos θ, to compensate for the variation of particles sampled within a reflection band does not maintain fidelity to the number of poles contributing to the diffracted signal. A new term, cos θB/cos θ, corrects this problem.

  5. On the magnetic structure of Er3Co: single-crystal neutron diffraction study

    SciTech Connect

    Gubkin, Andrey; Podlesnyak, Andrey A; Baranov, Nikolai

    2010-01-01

    The effect of the magnetic field applied along the main crystallographic directions on the magnetic structure of Er{sub 3}Co has been studied by means of single-crystal neutron diffraction technique. At zero field the compound exhibits a noncoplanar commensurate magnetic structure with ferromagnetic alignment of the Er magnetic-moment projections along the b axis in an orthorhombic unit cell. The present measurements revealed that the application of the magnetic field along the c direction [c {perpendicular} (ab)] leads to the pronounced metamagneticlike transition in the low-field region {mu}{sub 0}H < 1.2 T, although, the magnetization curve does not exhibit any anomalies. Combining the present single-crystal diffraction and magnetization data with the results of the previous powder neutron diffraction study [Gignoux et al., Solid State Commun. 8, 391 (1970)], we conclude that the nature of the magnetic ion, whether Kramers or non-Kramers, has a decisive effect on the commensurability of the magnetic structure of R{sub 3}Co. In particular, the commensurate magnetic structure observed in Er{sub 3}Co originate from the Kramers character of Er{sup 3+} ion in contrast to the incommensurate structures found earlier in R{sub 3}Co with R = Tb and Ho.

  6. Measurement of diffractive dijet production at the H1 experiment

    NASA Astrophysics Data System (ADS)

    Raičević, Nataša

    2016-03-01

    The new results on measurement of dijet production in diffractive deep inelastic ep scattering, ep → eXY, obtained with the H1 detector are presented. The system X contains at least two jets. Measurements are performed using two approaches. One approach is based on detection of the diffractive processes with Y being a proton or its low mass excitation. Diffractive events are selected by demanding a large empty rapidity gap interval separating the final state hadronic systems X and Y. In another approach, the leading final state proton from the process ep → eXp is detected in the H1 Very Forward Proton Spectrometer. The measurements are compared with predictions from NLO QCD calculations based on diffractive parton densities.

  7. Diffraction of a Bose-Einstein Condensate from a Magnetic Lattice on a Microchip

    SciTech Connect

    Guenther, A.; Kraft, S.; Kemmler, M.; Koelle, D.; Kleiner, R.; Zimmermann, C.; Fortagh, J.

    2005-10-21

    We experimentally study the diffraction of a Bose-Einstein condensate from a magnetic lattice, realized by a set of 372 parallel gold conductors which are microfabricated on a silicon substrate. The conductors generate a periodic potential for the atoms with a lattice constant of 4 {mu}m. After exposing the condensate to the lattice for several milliseconds we observe diffraction up to fifth order by standard time of flight imaging techniques. The experimental data can be quantitatively interpreted with a simple phase imprinting model. The demonstrated diffraction grating offers promising perspectives for the construction of an integrated atom interferometer.

  8. Magnet operating experience review for fusion applications

    SciTech Connect

    Cadwallader, L.C.

    1991-11-01

    This report presents a review of magnet operating experiences for normal-conducting and superconducting magnets from fusion, particle accelerator, medical technology, and magnetohydrodynamics research areas. Safety relevant magnet operating experiences are presented to provide feedback on field performance of existing designs and to point out the operational safety concerns. Quantitative estimates of magnet component failure rates and accident event frequencies are also presented, based on field experience and on performance of similar components in other industries.

  9. Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

    ERIC Educational Resources Information Center

    Velentzas, Athanasios

    2014-01-01

    Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such…

  10. Single-slit electron diffraction with Aharonov-Bohm phase: Feynman's thought experiment with quantum point contacts.

    PubMed

    Khatua, Pradip; Bansal, Bhavtosh; Shahar, Dan

    2014-01-10

    In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC). As the QPC width is comparable to the electron wavelength, the observed intensity profile is further modulated by the transverse waveguide modes present at the injector QPC. Our experiments open the way to realizing diffraction-based ideas in mesoscopic physics. PMID:24483873

  11. Single-slit electron diffraction with Aharonov-Bohm phase: Feynman's thought experiment with quantum point contacts.

    PubMed

    Khatua, Pradip; Bansal, Bhavtosh; Shahar, Dan

    2014-01-10

    In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC). As the QPC width is comparable to the electron wavelength, the observed intensity profile is further modulated by the transverse waveguide modes present at the injector QPC. Our experiments open the way to realizing diffraction-based ideas in mesoscopic physics.

  12. Single-Slit Electron Diffraction with Aharonov-Bohm Phase: Feynman's Thought Experiment with Quantum Point Contacts

    NASA Astrophysics Data System (ADS)

    Khatua, Pradip; Bansal, Bhavtosh; Shahar, Dan

    2014-01-01

    In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC). As the QPC width is comparable to the electron wavelength, the observed intensity profile is further modulated by the transverse waveguide modes present at the injector QPC. Our experiments open the way to realizing diffraction-based ideas in mesoscopic physics.

  13. Neutron diffraction, specific heat and magnetization studies on Nd2CuTiO6

    NASA Astrophysics Data System (ADS)

    Rayaprol, S.; Kaushik, S. D.; Kumar, Naresh; Singh, K.; Guillou, F.; Simon, C.

    2016-05-01

    Structural and physical properties of a double-perovskite compound, Nd2CuTiO6 have been studied using neutron diffraction, magnetization and specific heat measurements. The compound crystallizes in an orthorhombic structure in space group Pnma. The interesting observation we make here is that, though no long range magnetic order is observed between 2 and 300K, the low temperature specific heat and magnetic susceptibility behavior exhibits non-Fermi liquid like behavior in this insulating compound. The magnetization and specific heat data are presented and discussed in light of these observations.

  14. The magnetic structure of Co(NCNH)₂ as determined by (spin-polarized) neutron diffraction

    SciTech Connect

    Jacobs, Philipp; Houben, Andreas; Senyshyn, Anatoliy; Müller, Paul; Dronskowski, Richard

    2013-06-01

    The magnetic structure of Co(NCNH)₂ has been studied by neutron diffraction data below 10 K using the SPODI and DNS instruments at FRM II, Munich. There is an intensity change in the (1 1 0) and (0 2 0) reflections around 4 K, to be attributed to the onset of a magnetic ordering of the Co²⁺ spins. Four different spin orientations have been evaluated on the basis of Rietveld refinements, comprising antiferromagnetic as well as ferromagnetic ordering along all three crystallographic axes. Both residual values and supplementary susceptibility measurements evidence that only a ferromagnetic ordering with all Co²⁺ spins parallel to the c axis is a suitable description of the low-temperature magnetic ground state of Co(NCNH)₂. The deviation of the magnetic moment derived by the Rietveld refinement from the expectancy value may be explained either by an incomplete saturation of the moment at temperatures slightly below the Curie temperature or by a small Jahn–Teller distortion. - Graphical abstract: The magnetic ground state of Co(NCNH)₂ has been clarified by (spin-polarized) neutron diffraction data at low temperatures. Intensity changes below 4 K arise due to the onset of ferromagnetic ordering of the Co²⁺ spins parallel to the c axis, corroborated by various (magnetic) Rietveld refinements. Highlights: • Powderous Co(NCNH)₂ has been subjected to (spin-polarized) neutron diffraction. • Magnetic susceptibility data of Co(NCNH)₂ have been collected. • Below 4 K, the magnetic moments align ferromagnetically with all Co²⁺ spins parallel to the c axis. • The magnetic susceptibility data yield an effective magnetic moment of 4.68 and a Weiss constant of -13(2) K. • The ferromagnetic Rietveld refinement leads to a magnetic moment of 2.6 which is close to the expectancy value of 3.

  15. Instrumentation For Diffraction Enhanced Imaging Experiments At HASYLAB

    NASA Astrophysics Data System (ADS)

    Lohmann, M.; Dix, W.-R.; Metge, J.; Reime, B.

    2004-05-01

    The new X-ray radiography imaging technique, named diffraction enhanced imaging (DEI), enables almost scatter free absorption imaging, the production of the so-called refraction images of a sample. The images show improved contrast compared to standard imaging applications. At the HASYLAB wiggler beamline W2 at the 2nd-generation storage ring DORIS a 5cm wide beam with an adjustable energy between 10 and 70keV is available. A Si [111] pre-monochromator is used followed by the main monochromator using the (111) or the (333)-reflection. Visualization of fossils, detecting internal pearl structures, monitoring of bone and cartilage and documentation of implant healing in bone are application examples at HASYLAB.

  16. (X-ray diffraction experiments with condenser matter)

    SciTech Connect

    Coppens, P.

    1990-01-01

    This report discusses research on the following topics: high-{Tc} superconductors; The response of crystal to an applied electric field; quasicrystals; surface structure and kinetics of surface layer formation; EXAFS studies of superconductors and heterostructures; effect of iron on the crystal structure of perovskite; x-ray detector development; and SAXS experiments. (LSP)

  17. Neutron-diffraction study of the magnetic structure of PrCoAl 4

    NASA Astrophysics Data System (ADS)

    Schobinger-Papamantellos, P.; Wilkinson, C.; Tung, L. D.; Buschow, K. H. J.; McIntyre, G. J.

    2004-12-01

    The magnetic structure of PrCoAl4 has been studied by neutron diffraction from a single crystal. The Pr moments order at a temperature near to 20 K with a sine-wave longitudinal amplitude-modulated structure. The length of the wave vector q = (0 0qz) is almost temperature independent with qz = 0.4087 (5) , and only the first harmonic was observed down to 2 K. The amplitude of the wave, 2.05(3) μB/Pr atom at 2 K, is reduced compared to the Pr3+ free-ion moment value g JμB = 3.2μB , due to strong crystal-field effects. One difference between the present and previously reported neutron powder-diffraction results concerns the wave vector length. The reason for this may lie in the different magnetic microstructure (stacking faults) of the material depending on the thermochemical history of each sample.

  18. Modified magnetic field distribution in relativistic magnetron with diffraction output for compact operation

    SciTech Connect

    Li Wei; Liu Yonggui

    2011-02-15

    A modified magnetic field distribution in relativistic magnetron with diffraction output (MDO) for compact operation is proposed in this paper. The principle of how the modified magnetic field confines electrons drifting out of the interaction space is analyzed. The results of the particle-in-cell (PIC) simulations of the MDO with the modified magnetic field distribution show that the output power of the MDO is improved, and the long cylindrical waveguide used for collecting the drifting electrons can be omitted. The latter measure allows the horn antenna of the MDO to produce more focused energy with better directivity in the far field than it does with the long cylindrical waveguide. The MDO with the modified magnetic field distribution promises to be the real most compact narrow band high power microwave source.

  19. Misorientations in [001] magnetite thin films studied by electron backscatter diffraction and magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Wei, J. D.; Zhou, Y.; Murphy, S.; Mücklich, F.; Hartmann, U.; Shvets, I. V.

    2007-05-01

    Magnetite thin films grown on [001] oriented MgO substrates are analyzed by means of electron backscatter diffraction (EBSD) analysis and magnetic force microscopy in applied fields. The EBSD technique enables the crystallographic orientation of individual grains to be determined with a high spatial resolution up to 20nm on such ceramic samples. A high image quality of the recorded Kikuchi patterns was achieved enabling multiphase scans and high spatial resolution measurements. Upon annealing in air, the magnetic properties of the magnetite thin films were found to change considerably. Using the EBSD analysis, we find that misoriented grains remaining after the annealing step form small islands with a size of about 100nm. The size and distribution of these islands correspond well to the observations of antiferromagnetic pinning centers within the magnetic domain structures carried out by magnetic force microscopy on the same samples.

  20. Neutron diffraction texture analysis for α-Al2O3 oriented by high magnetic field and sintering

    NASA Astrophysics Data System (ADS)

    Terada, N.; Suzuki, H. S.; Suzuki, T. S.; Kitazawa, H.; Sakka, Y.; Kaneko, K.; Metoki, N.

    2009-05-01

    We have performed neutron diffraction experiments on highly oriented α-Al2O3, obtained by slip casting under a magnetic field and sintering. In order to investigate the magnetic field, B, and sintering temperature, Tsint, dependence of the degree of alignment of the orientation, we used samples treated with systematically varied B up to 12 T and Tsint up to 1600 °C. The degree of alignment of the magnetic easy axis (the hexagonal c-axis) is rapidly enhanced by sintering above 1200 °C, which is coincident with the temperature at which crystal grains start to grow. The angular distribution of the c-axis for the sample sintered at 1600 °C, obtained by ω-scan neutron diffraction profiles, is almost coincident with the probability distribution calculated for the particle size two times larger than that in the starting material. We discuss the orientation process mechanism with sintering in light of the results of this analysis.

  1. Pressure dependence of the magnetic order in CrAs: a neutron diffraction investigation

    SciTech Connect

    Keller, L.; White, J. S.; Babkevich, P.; Susner, Michael A.; Sims, Zachary C; Safa-Sefat, Athena; Ronnow, H. M.; Ruegg, Ch.

    2015-01-29

    The suppression of magnetic order with pressure concomitant with the appearance of pressure-induced superconductivity was recently discovered in CrAs. Here we present a neutron diffraction study of the pressure evolution of the helimagnetic ground-state towards and in the vicinity of the superconducting phase. Neutron diffraction on polycrystalline CrAs was employed from zero pressure to 0.65 GPa and at various temperatures. The helimagnetic long-range order is sustained under pressure and the magnetic propagation vector does not show any considerable change. The average ordered magnetic moment is reduced from 1.73(2) μB at ambient pressure to 0.4(1) μB close to the critical pressure Pc ≈ 0.7 GPa, at which magnetic order is completely suppressed. The width of the magnetic Bragg peaks strongly depends on temperature and pressure, showing a maximum in the region of the onset of superconductivity. In conclusion, we interpret this as associated with competing ground-states in the vicinity of the superconducting phase.

  2. Pressure dependence of the magnetic order in CrAs: a neutron diffraction investigation

    DOE PAGES

    Keller, L.; White, J. S.; Babkevich, P.; Susner, Michael A.; Sims, Zachary C; Safa-Sefat, Athena; Ronnow, H. M.; Ruegg, Ch.

    2015-01-29

    The suppression of magnetic order with pressure concomitant with the appearance of pressure-induced superconductivity was recently discovered in CrAs. Here we present a neutron diffraction study of the pressure evolution of the helimagnetic ground-state towards and in the vicinity of the superconducting phase. Neutron diffraction on polycrystalline CrAs was employed from zero pressure to 0.65 GPa and at various temperatures. The helimagnetic long-range order is sustained under pressure and the magnetic propagation vector does not show any considerable change. The average ordered magnetic moment is reduced from 1.73(2) μB at ambient pressure to 0.4(1) μB close to the critical pressuremore » Pc ≈ 0.7 GPa, at which magnetic order is completely suppressed. The width of the magnetic Bragg peaks strongly depends on temperature and pressure, showing a maximum in the region of the onset of superconductivity. In conclusion, we interpret this as associated with competing ground-states in the vicinity of the superconducting phase.« less

  3. Pressure dependence of the magnetic order in CrAs: A neutron diffraction investigation

    NASA Astrophysics Data System (ADS)

    Keller, L.; White, J. S.; Frontzek, M.; Babkevich, P.; Susner, M. A.; Sims, Z. C.; Sefat, A. S.; Rønnow, H. M.; Rüegg, Ch.

    2015-01-01

    The suppression of magnetic order with pressure concomitant with the appearance of pressure-induced superconductivity was recently discovered in CrAs. Here we present a neutron diffraction study of the pressure evolution of the helimagnetic ground state towards and in the vicinity of the superconducting phase. Neutron diffraction on polycrystalline CrAs was employed from zero pressure to 0.65 GPa and at various temperatures. The helimagnetic long-range order is sustained under pressure and the magnetic propagation vector does not show any considerable change. The average ordered magnetic moment is reduced from 1.73(2) μB at ambient pressure to 0.4(1) μB close to the critical pressure Pc≈0.7 GPa, at which magnetic order is completely suppressed. The width of the magnetic Bragg peaks strongly depends on temperature and pressure, showing a maximum in the region of the onset of superconductivity. We interpret this as associated with competing ground states in the vicinity of the superconducting phase.

  4. In situ X-ray powder diffraction, synthesis, and magnetic properties of InVO{sub 3}

    SciTech Connect

    Lundgren, Rylan J.; Cranswick, Lachlan M.D.; Bieringer, Mario . E-mail: Mario_Bieringer@umanitoba.ca

    2006-12-15

    We report the first synthesis and high-temperature in situ X-ray diffraction study of InVO{sub 3}. Polycrystalline InVO{sub 3} has been prepared via reduction of InVO{sub 4} using a carbon monoxide/carbon dioxide buffer gas. InVO{sub 3} crystallizes in the bixbyite structure in space group Ia-3 (206) with a=9.80636(31) A with In{sup 3+}/V{sup 3+} disorder on the (8b) and (24d) cation sites. In situ powder X-ray diffraction experiments and thermal gravimetric analysis in a CO/CO{sub 2} buffer gas revealed the existence of the metastable phase InVO{sub 3}. Bulk samples with 98.5(2)% purity were prepared using low-temperature reduction methods. The preparative methods limited the crystallinity of this new phase to approximately 225(50) A. Magnetic susceptibility and neutron diffraction experiments suggest a spin-glass ground state for InVO{sub 3}. - Graphical abstract: In situ powder X-ray diffractograms for the reduction of InVO{sub 4} in CO/CO{sub 2}. The three temperature regions show the conversion of InVO{sub 4} to InVO{sub 3} and final decomposition into In{sub 2}O{sub 3} and V{sub 2}O{sub 3}.

  5. Experiments With Magnetic Vector Potential

    ERIC Educational Resources Information Center

    Skinner, J. W.

    1975-01-01

    Describes the experimental apparatus and method for the study of magnetic vector potential (MVP). Includes a discussion of inherent errors in the calculations involved, precision of the results, and further applications of MVP. (GS)

  6. Teaching Diffraction of Light and Electrons: Classroom Analogies to Classic Experiments

    NASA Astrophysics Data System (ADS)

    Velentzas, Athanasios

    2014-11-01

    Diffraction and interference are phenomena that demonstrate the wave nature of light and of particles. Experiments relating to the diffraction/interference of light can easily be carried out in an educational lab, but it may be impossible to perform experiments involving electrons because of the lack of specialized equipment needed for such experiments. It would, however, be possible for students to analyze data from scientific experiments by analogy to experiments they themselves had performed. Based on this rationale, this paper describes two pairs of experiments that may be of interest to teachers aiming to teach the wave nature of light and of particles to upper secondary school (or to college) students. Specifically, students are asked to (i) carry out a double-slit experiment by using monochromatic light, thus repeating in a way the historical experiment of Young,1 and then analyze real data from Jönsson's2-3 scientific double-slit experiment with electrons, and (ii) perform an experiment involving diffraction of monochromatic light using a compact disc (CD) as a reflection grating, and then by analogy analyze data from the experiment of Davisson and Germer.4 The proposed real experiments are not original, and different versions of them have been wi dely described in the literature.5,6 The educational value of the present work lies in the use of the analogy between experiments carried out in the school lab and experiments performed in the scientific lab.

  7. Magnetic Levitation Experiments with the Electrodynamic Wheel

    NASA Astrophysics Data System (ADS)

    Cordrey, Vincent; Gutarra-Leon, Angel; Gaul, Nathan; Majewski, Walerian

    Our experiments explored inductive magnetic levitation using circular Halbach arrays with the strong variable magnetic field on the outer rim of the ring. Such a system is usually called an Electrodynamic Wheel (EDW). Rotating this wheel around a horizontal axis above a flat conducting surface should induce eddy currents in said surface through the variable magnetic flux. The eddy currents produce, in turn, their own magnetic fields which interact with the magnets of the EDW. We constructed two Electrodynamic Wheels with different diameters and demonstrated that the magnetic interactions produce both lift and drag forces on the EDW which can be used for levitation and propulsion of the EDW. The focus of our experiments is the direct measurement of lift and drag forces to compare with theoretical models using wheels of two different radii. Supported by Grants from the Virginia Academy of Science, Society of Physics Students, Virginia Community College System, and the NVCC Educational Foundation.

  8. Plasmonic localized heating beyond the diffraction limit via magnetic polariton excitation

    NASA Astrophysics Data System (ADS)

    Alshehri, Hassan; Ying, Xiaoyan; Wang, Hao; Wang, Liping

    2016-09-01

    Optical localized heating in the nanoscale has recently attracted great attention due to its unique small hot spot size with high energy. However, the hot spot size is conventionally constrained by the diffraction limit. Plasmonic localized heating can provide solutions to this limitation in nanoscale patterning, cancer treatment, and data storage. Plasmonic approaches to overcome the diffraction limit in hot spot size have mainly utilized the excitation of surface plasmon or localized surface plasmon resonance. However, achieving plasmonic localized heating by the excitation of magnetic polariton has not been researched extensively yet. In this work, we numerically investigated the optical response of a nanoscale metamaterial composed of a gold nanowire array and a gold film separated by an ultrathin polymer spacer using ANSYS High Frequency Structural Simulator. A strong absorption peak at the wavelength of 760 nm was exhibited, and the underlying physical mechanism for the strong absorption was verified via the local electromagnetic field distribution to be magnetic resonance excitation. An inductor-capacitor circuit model was used to predict the magnetic resonance wavelength and compare with the numerical results for varied geometrical parameters. Volume loss density due to the strong local optical energy confinement was transferred as heat generation to an ANSYS thermal solver to obtain the local temperature profile. The steady state temperature profile shows an average temperature of 145 °C confined in a local area as small as 33 nm within the spacer, with a full-width at half-maximum of 50 nm along the x-direction. Moreover, the temperature rise from ambient drops to half its maximum value at a distance of 5 nm from the top of the spacer along the z-direction. This clearly demonstrates plasmonic localized heating beyond the diffraction limit via magnetic polariton excitation. Furthermore, the transient temperature profile shows that the system reached

  9. Mikhailov's experiments on detection of magnetic charge

    SciTech Connect

    Akers, D.

    1988-08-01

    In a reanalysis of Mikhailov's experiments, it is argued that observations of magnetic charge g = (1/2)(1/137)(1/3)e on ferromagnetic aerosols are incorrect. Future experiments of the type conducted by Mikhailov must take into an account the component of particle velocity orthogonal to E and H. It is shown that Mikhailov's data are consistent with the existence of a Dirac unit of magnetic charge g = (137/2)e found in meson spectroscopy.

  10. A neutron diffraction and magnetic Barkhausen noise evaluation of defect-induced stress concentrations

    NASA Astrophysics Data System (ADS)

    Sabet-Sharghi, Riaz

    This thesis studies the effect of altering both the drilling technique (mechanical drilling vs. Electro-Chemical Milling) and the sequence of defect introduction and load application on the defect-induced stress distributions in sections of line pipe steel material. The defect-induced stress concentrations in loaded samples with defects introduced whilst loaded (in-situ) and prior to the application of load (pre-drilled) were examined using both neutron diffraction and Magnetic Barkhausen Noise (MBN). These results indicated the presence of potentially large levels of residual stress particularly in the in-situ sample. This is believed to be a result of plastic deformation being introduced by the mechanical drilling process. Similar studies on ECM defects showed no signs of drilling-induced stresses. Experimental stress distribution results from the in-situ and pre-drilled samples were compared to those predicted using a three-dimensional finite element model solution. The overall level of agreement was found to be best for the pre-drilled sample case. The study also aimed to determine the effectiveness of MBN as a non-destructive method for characterizing line pipe samples. Results of an initial experiment are presented showing the effectiveness of MBN for performing quantitative strain analysis on samples. This was determined by comparing MBN-measured stress concentrations with those predicted by theory and reported in the literature. Magnetic Flux Leakage (MFL) tests were also performed on the samples in order to examine any stress-induced differences in MFL response. It was found that the differences in stress distribution between the in-situ and pre-drilled samples were also reflected in the trend of the MFL signal amplitude and shape as a function of applied stress. The original work in this thesis includes the first definitive test of the effects of the order of load application and defect introduction on the resulting stress distributions around through

  11. Structure, magnetic properties, polarized neutron diffraction, and theoretical study of a copper(II) cubane.

    PubMed

    Aronica, Christophe; Chumakov, Yurii; Jeanneau, Erwann; Luneau, Dominique; Neugebauer, Petr; Barra, Anne-Laure; Gillon, Béatrice; Goujon, Antoine; Cousson, Alain; Tercero, Javier; Ruiz, Eliseo

    2008-01-01

    The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations. PMID:18792037

  12. Crystal and magnetic structures of Cr1/3NbSe2 from neutron diffraction

    NASA Astrophysics Data System (ADS)

    Gubkin, A. F.; Proskurina, E. P.; Kousaka, Y.; Sherokalova, E. M.; Selezneva, N. V.; Miao, P.; Lee, S.; Zhang, J.; Ishikawa, Y.; Torii, S.; Kamiyama, T.; Campo, J.; Akimitsu, J.; Baranov, N. V.

    2016-01-01

    Neutron diffraction measurements of the Cr intercalated niobium diselenide Cr1/3NbSe2 together with magnetization measurements have revealed that this compound exhibits ferromagnetic ordering below TC = 96 K unlike a chiral helimagnetic order observed in the sulfide compound Cr1/3NbS2. As derived from neutron diffraction data, the Cr magnetic moments μCr = 2.83 ± 0.03 μB in Cr1/3NbSe2 are aligned within basal plane. The discrepancy in the magnetic states of Cr1/3NbS2 and Cr1/3NbSe2 is ascribed to the difference in the preferential site occupation of Cr ions in crystal lattices. In Cr1/3NbSe2, the Cr ions are predominantly distributed over 2b Wyckoff site, which determines a centrosymmetric character of the crystal structure unlike Cr1/3NbS2, where the Cr ions are mainly located in 2c position and the crystal structure is non-centrosymmetric.

  13. Zeeman spectrum, magnetic neutron diffraction pattern, and Dirac multipoles for a multiferroic material Cu B2O4

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.

    2016-09-01

    Zeeman spectra, dichroic signals, and neutron Bragg diffraction patterns generated by copper ions in magnetically ordered copper metaborate (Cu B2O4 ) are investigated within a minimal model of Cu atomic states. A theory platform, common to understanding optical spectra and neutron diffraction patterns, affords the immediate benefit of a unified description of the experimental probes in terms of electronic multipoles. Results for dichroic signals illustrate a nontrivial use of a general, quantum mechanical theory of photon absorption couched in terms of Dirac multipoles that are magnetic and polar. Anapoles (Dirac dipoles) are predicted to generate Bragg spots in magnetic neutron diffraction that are not indexed by the motif of conventional (axial) magnetic-dipole moments. The minimal model of Cu states is informed by magnetic symmetry, derived from an established commensurate antiferromagnetic order, with a sparse number of parameters that comply with available empirical evidence.

  14. Experiment pointing with magnetic suspension

    NASA Technical Reports Server (NTRS)

    Hamilton, B. J.

    1981-01-01

    A need has been identified for a payload auxilliary pointing system onboard the Space Shuttle which provides sub-arcsecond stability in the Shuttle disturbance environment. This paper describes such a pointing system, presently being developed by Sperry Flight Systems for the NASA Langley Research Center. At the core of the design is a non-contacting magnetic suspension which provides a high degree of isolation between payload and carrier. Design concepts and control laws will be discussed. Also, test results from full-scale protoflight hardware and planned system refinements will be presented.

  15. Lorentz microscopy and small-angle electron diffraction study of magnetic textures in L a1 -xS rxMn O3 (0.15 magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Kotani, A.; Nakajima, H.; Harada, K.; Ishii, Y.; Mori, S.

    2016-07-01

    Magnetic textures in the ferromagnetic phases of L a1 -xS rxMn O3 for 0.15 diffraction experiments. Various types of magnetic textures characterized by stripe, plate-shaped, and cylindrical (magnetic bubble) domains were found. Two distinct types of magnetic stripe domains appeared in the orthorhombic structure with an inversion symmetry of L a0.825S r0.175Mn O3 , depending significantly on magnetocrystalline anisotropy. Based on in situ observations as functions of temperature and the strength of the external magnetic field, a magnetic field-temperature phase diagram was constructed, showing the stabilization of magnetic bubbles in the ferromagnetic phase of L a0.825S r0.175Mn O3 .

  16. Diffraction-induced subradiant transverse-magnetic lattice plasmon modes in metal nanoparticle arrays

    SciTech Connect

    Nikitin, Andrey G.

    2014-02-10

    This Letter reports theoretical and experimental study of transverse-magnetic-like lattice plasmon modes originating from diffraction in periodic two dimensional arrays of metal nanoparticles. These modes lead to the transmission and reflection spectra exhibiting narrow linewidth Fano-like resonances which can appear as maxima, minima, or can have asymmetric peak-and-dip profile. The dependencies of the position and lineshape of the resonance on the lattice periodicity and angle of incidence are investigated. Numerical simulations of electric field distributions for different excitation conditions of lattice plasmon modes are also performed.

  17. Diffraction-induced subradiant transverse-magnetic lattice plasmon modes in metal nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Nikitin, Andrey G.

    2014-02-01

    This Letter reports theoretical and experimental study of transverse-magnetic-like lattice plasmon modes originating from diffraction in periodic two dimensional arrays of metal nanoparticles. These modes lead to the transmission and reflection spectra exhibiting narrow linewidth Fano-like resonances which can appear as maxima, minima, or can have asymmetric peak-and-dip profile. The dependencies of the position and lineshape of the resonance on the lattice periodicity and angle of incidence are investigated. Numerical simulations of electric field distributions for different excitation conditions of lattice plasmon modes are also performed.

  18. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J.; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K, respectively.

  19. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J. Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

  20. Development of MnBi permanent magnet: neutron diffraction of MnBi powder

    SciTech Connect

    Cui, Jun; Choi, Jung-Pyung; Li, Guosheng; Polikarpov, Evgueni; Darsell, Jens T.; Kramer, Matthew J.; Zarkevich, Nikolai; Wang, L. L.; Johnson, D. D.; Marinescu, Melania; Huang, Qingzhen; Wu, Hui; Vuong, Nguyen V.; Liu, J.Ping

    2014-03-05

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained power. The result shows that the purity of the obtained powder is about 91wt.% at 300K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K respectively.

  1. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

  2. An experiment on magnetic induction pulses

    NASA Astrophysics Data System (ADS)

    Manzanares, José A.; Bisquert, Juan; Garcia-Belmonte, Germà; Fernández-Alonso, Mercedes

    1994-08-01

    The voltage pulse induced by a bar magnet as it moves at constant velocity through the axis of a circular coil is analyzed. The physical system considered has a number of interesting features: (a) It is easy to set up and handle in the laboratory, (b) the observed pulse can be predicted theoretically by means of a simple model, and (c) it provides a very vivid and direct illustration of the concept of electromagnetic induction. In fact, the system of a coil and magnet in relative motion is usually presented in textbooks when introducing this concept. The experiment can also be used as a procedure for determining the magnetic dipole moment of magnets. Since the equipment, a digital storage oscilloscope or computer, is usually available in undergraduate laboratories, the experiment can be performed in the introductory physics course.

  3. Development of low temperature and high magnetic field X-ray diffraction facility

    NASA Astrophysics Data System (ADS)

    Shahee, Aga; Sharma, Shivani; Singh, K.; Lalla, N. P.; Chaddah, P.

    2015-06-01

    The current progress of materials science regarding multifunctional materials (MFM) has put forward the challenges to understand the microscopic origin of their properties. Most of such MFMs have magneto-elastic correlations. To investigate the underlying mechanism it is therefore essential to investigate the structural properties in the presence of magnetic field. Keeping this in view low temperature and high magnetic field (LTHM) powder x-ray diffraction (XRD), a unique state-of-art facility in the country has been developed at CSR Indore. This setup works on symmetric Bragg Brentano geometry using a parallel incident x-ray beam from a rotating anode source working at 17 kW. Using this one can do structural studies at non-ambient conditions i.e. at low- temperatures (2-300 K) and high magnetic field (+8 to -8 T). The available scattering angle ranges from 5° to 115° 2θ with a resolution better than 0.1°. The proper functioning of the setup has been checked using Si sample. The effect of magnetic field on the structural properties has been demonstrated on Pr0.5Sr0.5MnO3 sample. Clear effect of field induced phase transition has been observed. Moreover, the effect of zero field cooled and field cooled conditions is also observed.

  4. Development of low temperature and high magnetic field X-ray diffraction facility

    SciTech Connect

    Shahee, Aga; Sharma, Shivani; Singh, K.; Lalla, N. P. Chaddah, P.

    2015-06-24

    The current progress of materials science regarding multifunctional materials (MFM) has put forward the challenges to understand the microscopic origin of their properties. Most of such MFMs have magneto-elastic correlations. To investigate the underlying mechanism it is therefore essential to investigate the structural properties in the presence of magnetic field. Keeping this in view low temperature and high magnetic field (LTHM) powder x-ray diffraction (XRD), a unique state-of-art facility in the country has been developed at CSR Indore. This setup works on symmetric Bragg Brentano geometry using a parallel incident x-ray beam from a rotating anode source working at 17 kW. Using this one can do structural studies at non-ambient conditions i.e. at low- temperatures (2-300 K) and high magnetic field (+8 to −8 T). The available scattering angle ranges from 5° to 115° 2θ with a resolution better than 0.1°. The proper functioning of the setup has been checked using Si sample. The effect of magnetic field on the structural properties has been demonstrated on Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} sample. Clear effect of field induced phase transition has been observed. Moreover, the effect of zero field cooled and field cooled conditions is also observed.

  5. Neutron diffraction study of the magnetic structure of Na2 RuO 4

    NASA Astrophysics Data System (ADS)

    Mogare, K. M.; Sheptyakov, D. V.; Bircher, R.; Güdel, H.-U.; Jansen, M.

    2006-08-01

    Nuclear and magnetic structures of sodium ruthenate (VI) have been studied by neutron powder diffraction in the temperature range 1.5 200 K. Na2RuO4 crystallizes in the monoclinic structure, with space group P 21/c. The structure consists of apical corner sharing RuO5 trigonal bipyramids forming infinite chains running along the b axis. These infinite [ RuO3O2/2] chains form a pseudo hexagonal close packing of rods with Ru Ru distances of 3.51 Å within the chains and 5.30 5.47 Å between the chains. At TN=37.2 K a magnetic transition leads to an antiferromagnetic state. The Ru6+ magnetic moments are ordered antiferromagnetically along the chains (b-axis), while the inter-chain interaction is ferromagnetic. A classical infinite chain model was fitted to the magnetic susceptibility data in order to estimate the strength of the nearest-neighbor exchange interactions along and between the chains, resulting in an intrachain coupling parameter of 2J=-86 K, and an interchain parameter J⊥ with \\vert 2J⊥ \\vert = 3 K.

  6. Magnetic Nozzle and Plasma Detachment Experiment

    NASA Technical Reports Server (NTRS)

    Chavers, Gregory; Dobson, Chris; Jones, Jonathan; Martin, Adam; Bengtson, Roger D.; Briezman, Boris; Arefiev, Alexey; Cassibry, Jason; Shuttpelz, Branwen; Deline, Christopher

    2006-01-01

    High power plasma propulsion can move large payloads for orbit transfer (such as the ISS), lunar missions, and beyond with large savings in fuel consumption owing to the high specific impulse. At high power, lifetime of the thruster becomes an issue. Electrodeless devices with magnetically guided plasma offer the advantage of long life since magnetic fields confine the plasma radially and keep it from impacting the material surfaces. For decades, concerns have been raised about the plasma remaining attached to the magnetic field and returning to the vehicle along the closed magnetic field lines. Recent analysis suggests that this may not be an issue of the magnetic field is properly shaped in the nozzle region and the plasma has sufficient energy density to stretch the magnetic field downstream. An experiment was performed to test the theory regarding the Magneto-hydrodynamic (MHD) detachment scenario. Data from this experiment will be presented. The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) being developed by the Ad Astra Rocket Company uses a magnetic nozzle as described above. The VASIMR is also a leading candidate for exploiting an electric propulsion test platform being considered for the ISS.

  7. Thermal neutron diffraction determination of the magnetic structure of EuCu{sub 2}Ge{sub 2}

    SciTech Connect

    Rowan-Weetaluktuk, W. N.; Ryan, D. H.; Lemoine, P.; Cadogan, J. M.

    2014-05-07

    The magnetic structure of EuCu{sub 2}Ge{sub 2} has been determined by flat-plate neutron powder diffraction. Two magnetic phases are present in the neutron diffraction pattern at 3.5 K. They have the same moment, within error, and a common transition temperature. Both {sup 151}Eu and {sup 153}Eu Mössbauer spectroscopy show that the two magnetic phases belong to the same crystallographic phase. Both phases can be modelled by planar helimagnetic structures: one with a propagation vector of [0.654(1), 0, 0], the other with a propagation vector of [0.410(1), 0.225(1), 0].

  8. Connecting heterogeneous single slip to diffraction peak evolution in high-energy monochromatic X-ray experiments.

    PubMed

    Pagan, Darren C; Miller, Matthew P

    2014-06-01

    A forward modeling diffraction framework is introduced and employed to identify slip system activity in high-energy diffraction microscopy (HEDM) experiments. In the framework, diffraction simulations are conducted on virtual mosaic crystals with orientation gradients consistent with Nye's model of heterogeneous single slip. Simulated diffraction peaks are then compared against experimental measurements to identify slip system activity. Simulation results compared against diffraction data measured in situ from a silicon single-crystal specimen plastically deformed under single-slip conditions indicate that slip system activity can be identified during HEDM experiments.

  9. Data Exploration Toolkit for serial diffraction experiments

    SciTech Connect

    Zeldin, Oliver B.; Brewster, Aaron S.; Hattne, Johan; Uervirojnangkoorn, Monarin; Lyubimov, Artem Y.; Zhou, Qiangjun; Zhao, Minglei; Weis, William I.; Sauter, Nicholas K.; Brunger, Axel T.

    2015-01-23

    Ultrafast diffraction at X-ray free-electron lasers (XFELs) has the potential to yield new insights into important biological systems that produce radiation-sensitive crystals. An unavoidable feature of the 'diffraction before destruction' nature of these experiments is that images are obtained from many distinct crystals and/or different regions of the same crystal. Combined with other sources of XFEL shot-to-shot variation, this introduces significant heterogeneity into the diffraction data, complicating processing and interpretation. To enable researchers to get the most from their collected data, a toolkit is presented that provides insights into the quality of, and the variation present in, serial crystallography data sets. These tools operate on the unmerged, partial intensity integration results from many individual crystals, and can be used on two levels: firstly to guide the experimental strategy during data collection, and secondly to help users make informed choices during data processing.

  10. Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto.

    PubMed

    Yanagisawa, Yasuhide; Chatake, Toshiyuki; Chiba-Kamoshida, Kaori; Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki; Yasuda, Ichiro; Morimoto, Yukio

    2010-12-01

    Nattokinase is a single polypeptide chain composed of 275 amino acids (molecular weight 27,724) which displays strong fibrinolytic activity. Moreover, it can activate other fibrinolytic enzymes such as pro-urokinase and tissue plasminogen activator. In the present study, native nattokinase from Bacillus subtilis natto was purified using gel-filtration chromatography and crystallized to give needle-like crystals which could be used for X-ray diffraction experiments. The crystals belonged to space group C2, with unit-cell parameters a=74.3, b=49.9, c=56.3 Å, β=95.2°. Diffraction images were processed to a resolution of 1.74 Å with an Rmerge of 5.2% (15.3% in the highest resolution shell) and a completeness of 69.8% (30.0% in the highest resolution shell). This study reports the first X-ray diffraction analysis of nattokinase.

  11. Electron back scattered diffraction characterization of Sm(CoFeCuZr){sub z} magnets

    SciTech Connect

    Yonamine, T.; Fukuhara, M.; Archanjo, B. S.; Missell, F. P.

    2011-04-01

    In permanent magnets based on the Sm{sub 2}Co{sub 17} phase, the high coercivity depends on the presence of a complex microstructure, consisting of a Sm{sub 2}(Co,Fe){sub 17} cell phase, a cell boundary phase Sm(Co,Cu){sub 5}, and a Zr-rich platelet or lamellae phase. The aim of this work is to use electron back scatter diffraction (EBSD) in order to identify the different phases present in the isotropic magnets produced from cast alloys with the composition of Sm(Co{sub bal}Fe{sub 0.2}Cu{sub 0.1}Zr{sub x}){sub 8}, where x = 0, 0.02, or 0.06, and correlate them with the different phases observed in scanning electron microscopy (SEM) images. Due to the combination of careful surface preparation and high resolution microscopy, it was possible to observe the cellular structure characteristic of the 2:17 magnets in the SEM images. Until now, only transmission electron microscopy (TEM) had been used. Composition maps, energy dispersive spectroscopy (EDS), and EBSD measurements were used for doing the phase identification.

  12. Neutron and X-ray single-crystal diffraction from protein microcrystals via magnetically oriented microcrystal arrays in gels.

    PubMed

    Tsukui, Shu; Kimura, Fumiko; Kusaka, Katsuhiro; Baba, Seiki; Mizuno, Nobuhiro; Kimura, Tsunehisa

    2016-07-01

    Protein microcrystals magnetically aligned in D2O hydrogels were subjected to neutron diffraction measurements, and reflections were observed for the first time to a resolution of 3.4 Å from lysozyme microcrystals (∼10 × 10 × 50 µm). This result demonstrated the possibility that magnetically oriented microcrystals consolidated in D2O gels may provide a promising means to obtain single-crystal neutron diffraction from proteins that do not crystallize at the sizes required for neutron diffraction structure determination. In addition, lysozyme microcrystals aligned in H2O hydrogels allowed structure determination at a resolution of 1.76 Å at room temperature by X-ray diffraction. The use of gels has advantages since the microcrystals are measured under hydrated conditions.

  13. A 31 T split-pair pulsed magnet for single crystal x-ray diffraction at low temperature

    SciTech Connect

    Duc, F.; Frings, P.; Nardone, M.; Billette, J.; Zitouni, A.; Delescluse, P.; Béard, J.; Nicolin, J. P.; Rikken, G. L. J. A.; Fabrèges, X.; Roth, T.; Detlefs, C.; Lesourd, M.; Zhang, L.

    2014-05-15

    We have developed a pulsed magnet system with panoramic access for synchrotron x-ray diffraction in magnetic fields up to 31 T and at low temperature down to 1.5 K. The apparatus consists of a split-pair magnet, a liquid nitrogen bath to cool the pulsed coil, and a helium cryostat allowing sample temperatures from 1.5 up to 250 K. Using a 1.15 MJ mobile generator, magnetic field pulses of 60 ms length were generated in the magnet, with a rise time of 16.5 ms and a repetition rate of 2 pulses/h at 31 T. The setup was validated for single crystal diffraction on the ESRF beamline ID06.

  14. CCD-based X-ray area detector for time-resolved diffraction experiments.

    PubMed

    Yagi, Naoto; Inoue, Katsuaki; Oka, Toshihiko

    2004-11-01

    A fast X-ray area detector for diffraction, scattering and imaging experiments at microsecond to millisecond time resolution has been developed. The key element of the detector is a fast (291 frames s(-1)) framing camera with three CCDs. A prism forms identical images on the CCDs and the frame rate is increased three times by reading them alternately. In order to convert X-rays into visible light that is detectable with the CCDs, an X-ray image intensifier is used. The camera can also be used with a high-resolution X-ray detector. In both cases it was found to be important to use a phosphor with a short decay time to fully make use of the high-speed framing capability of the camera. Preliminary results of a fibre diffraction experiment on a skeletal muscle and coronary angiography are presented.

  15. The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

    PubMed Central

    Bergamaschi, Anna; Cervellino, Antonio; Dinapoli, Roberto; Gozzo, Fabia; Henrich, Beat; Johnson, Ian; Kraft, Philipp; Mozzanica, Aldo; Schmitt, Bernd; Shi, Xintian

    2010-01-01

    The MYTHEN single-photon-counting silicon microstrip detector has been developed at the Swiss Light Source for time-resolved powder diffraction experiments. An upgraded version of the detector has been installed at the SLS powder diffraction station allowing the acquisition of diffraction patterns over 120° in 2θ in fractions of seconds. Thanks to the outstanding performance of the detector and to the calibration procedures developed, the quality of the data obtained is now comparable with that of traditional high-resolution point detectors in terms of FWHM resolution and peak profile shape, with the additional advantage of fast and simultaneous acquisition of the full diffraction pattern. MYTHEN is therefore optimal for time-resolved or dose-critical measurements. The characteristics of the MYTHEN detector together with the calibration procedures implemented for the optimization of the data are described in detail. The refinements of two known standard powders are discussed together with a remarkable application of MYTHEN to organic compounds in relation to the problem of radiation damage. PMID:20724787

  16. Neutron diffraction study of MnNiGa{sub 2}—Structural and magnetic behaviour

    SciTech Connect

    Wang, J. L.; Ma, L.; Wu, G. H.; Hofmann, M.; Avdeev, M.; Kennedy, S. J.; Campbell, S. J.; Md Din, M. F.; Dou, S. X.; Hoelzel, M.

    2014-05-07

    MnNiGa{sub 2} crystallizes in the L21 (Heusler) structure and has a ferromagnetic ordering temperature T{sub C} ∼ 192 K. Rietveld refinement of the neutron diffraction patterns indicates that the Ga atoms occupy the equivalent 8c position, while Mn and Ni share the 4a (0, 0, 0) and 4b (0.5, 0.5, 0.5) sites with a mixed occupancy of Mn and Ni atoms. It is found that that ∼83% of Mn and ∼17% Ni are located at the 4a site while ∼83% of Ni and ∼17% Mn occupy the 4b site. There is no evidence of a magneto-volume effect around T{sub C}. In agreement with this finding, our detailed critical exponent analyses of isothermal magnetization curves and the related Arrott plots confirm that the magnetic phase transition at T{sub C} is second order.

  17. Magnetic Flux Compression Experiments Using Plasma Armatures

    NASA Technical Reports Server (NTRS)

    Turner, M. W.; Hawk, C. W.; Litchford, R. J.

    2003-01-01

    Magnetic flux compression reaction chambers offer considerable promise for controlling the plasma flow associated with various micronuclear/chemical pulse propulsion and power schemes, primarily because they avoid thermalization with wall structures and permit multicycle operation modes. The major physical effects of concern are the diffusion of magnetic flux into the rapidly expanding plasma cloud and the development of Rayleigh-Taylor instabilities at the plasma surface, both of which can severely degrade reactor efficiency and lead to plasma-wall impact. A physical parameter of critical importance to these underlying magnetohydrodynamic (MHD) processes is the magnetic Reynolds number (R(sub m), the value of which depends upon the product of plasma electrical conductivity and velocity. Efficient flux compression requires R(sub m) less than 1, and a thorough understanding of MHD phenomena at high magnetic Reynolds numbers is essential to the reliable design and operation of practical reactors. As a means of improving this understanding, a simplified laboratory experiment has been constructed in which the plasma jet ejected from an ablative pulse plasma gun is used to investigate plasma armature interaction with magnetic fields. As a prelude to intensive study, exploratory experiments were carried out to quantify the magnetic Reynolds number characteristics of the plasma jet source. Jet velocity was deduced from time-of-flight measurements using optical probes, and electrical conductivity was measured using an inductive probing technique. Using air at 27-inHg vacuum, measured velocities approached 4.5 km/s and measured conductivities were in the range of 30 to 40 kS/m.

  18. VINETA II: a linear magnetic reconnection experiment.

    PubMed

    Bohlin, H; Von Stechow, A; Rahbarnia, K; Grulke, O; Klinger, T

    2014-02-01

    A linear experiment dedicated to the study of driven magnetic reconnection is presented. The new device (VINETA II) is suitable for investigating both collisional and near collisionless reconnection. Reconnection is achieved by externally driving magnetic field lines towards an X-point, inducing a current in the background plasma which consequently modifies the magnetic field topology. Owing to the open field line configuration of the experiment, the current is limited by the axial sheath boundary conditions. A plasma gun is used as an additional electron source in order to counterbalance the charge separation effects and supply the required current. Two drive methods are used in the device. First, an oscillating current through two parallel conductors drive the reconnection. Second, a stationary X-point topology is formed by the parallel conductors, and the drive is achieved by an oscillating current through a third conductor. In the first setup, the magnetic field of the axial plasma current dominates the field topology near the X-point throughout most of the drive. The second setup allows for the amplitude of the plasma current as well as the motion of the flux to be set independently of the X-point topology of the parallel conductors.

  19. VINETA II: A linear magnetic reconnection experiment

    SciTech Connect

    Bohlin, H. Von Stechow, A.; Rahbarnia, K.; Grulke, O.; Klinger, T.

    2014-02-15

    A linear experiment dedicated to the study of driven magnetic reconnection is presented. The new device (VINETA II) is suitable for investigating both collisional and near collisionless reconnection. Reconnection is achieved by externally driving magnetic field lines towards an X-point, inducing a current in the background plasma which consequently modifies the magnetic field topology. Owing to the open field line configuration of the experiment, the current is limited by the axial sheath boundary conditions. A plasma gun is used as an additional electron source in order to counterbalance the charge separation effects and supply the required current. Two drive methods are used in the device. First, an oscillating current through two parallel conductors drive the reconnection. Second, a stationary X-point topology is formed by the parallel conductors, and the drive is achieved by an oscillating current through a third conductor. In the first setup, the magnetic field of the axial plasma current dominates the field topology near the X-point throughout most of the drive. The second setup allows for the amplitude of the plasma current as well as the motion of the flux to be set independently of the X-point topology of the parallel conductors.

  20. Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Seedhouse, Steven J.; Hoffmann, Markus M.

    2008-01-01

    A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

  1. Polarized-neutron-diffraction study of the microscopic magnetic structure in α''-Fe 16N2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hiraka, H.; Ohoyama, K.; Ogata, Y.; Ogawa, T.; Gallage, R.; Kobayashi, N.; Takahashi, M.; Gillon, B.; Gukasov, A.; Yamada, K.

    2014-10-01

    Polarized-neutron-diffraction (PND) measurements were carried out using a pseudo-single-phase powder sample of ferromagnetic α''-Fe16N2 nanoparticles. For the well-identified α''-Fe16N2 phase, sizes of the magnetic moments at the three crystallographic Fe sites were determined in the absolute scale. The agreement between the magnetization value deduced from the present PND and that measured by a magnetometer (MVSM) supports the hypothesis that MVSM is primarily caused by the magnetization value in the target α''-Fe16N2 ; thus there is no evidence for macroscopic giant saturation magnetization, at least for α''-Fe16N2 nanoparticles. On the basis of the large magnetic moment size at one of the Fe sites, a possible coexisting state of localized spins and itinerant electron spins is inferred. Drawing a distinction between thin films and nanoparticles is currently necessary because of their divergent magnetic evolutions.

  2. A facility for X-ray diffraction in magnetic fields up to 25 T and temperatures between 15 and 295 K

    SciTech Connect

    Wang, S.; Kovalev, A. E. Suslov, A. V.; Siegrist, T.

    2015-12-15

    A facility for X-ray diffraction has been developed at the National High Magnetic Field Laboratory. It brings diffraction capability to the 25 T Florida split coil magnet and implements temperature control in a range of 15–295 K using a cold finger helium cryostat. This instrument represents an alternative to pulsed magnetic field systems, and it exceeds the static magnetic fields currently available at synchrotron facilities. Magnetic field compatibility of an X-ray source and detectors with the sizable magnetic fringe fields emanating from the magnet constrained the design of the diffractometer.

  3. The use of a mini-κ goniometer head in macromolecular crystallography diffraction experiments

    PubMed Central

    Brockhauser, Sandor; Ravelli, Raimond B. G.; McCarthy, Andrew A.

    2013-01-01

    Most macromolecular crystallography (MX) diffraction experiments at synchrotrons use a single-axis goniometer. This markedly contrasts with small-molecule crystallography, in which the majority of the diffraction data are collected using multi-axis goniometers. A novel miniaturized κ-gonio­meter head, the MK3, has been developed to allow macromolecular crystals to be aligned. It is available on the majority of the structural biology beamlines at the ESRF, as well as elsewhere. In addition, the Strategy for the Alignment of Crystals (STAC) software package has been developed to facilitate the use of the MK3 and other similar devices. Use of the MK3 and STAC is streamlined by their incorporation into online analysis tools such as EDNA. The current use of STAC and MK3 on the MX beamlines at the ESRF is discussed. It is shown that the alignment of macromolecular crystals can result in improved diffraction data quality compared with data obtained from randomly aligned crystals. PMID:23793150

  4. The use of a mini-κ goniometer head in macromolecular crystallography diffraction experiments

    SciTech Connect

    Brockhauser, Sandor; Ravelli, Raimond B. G.; McCarthy, Andrew A.

    2013-07-01

    Hardware and software solutions for MX data-collection strategies using the EMBL/ESRF miniaturized multi-axis goniometer head are presented. Most macromolecular crystallography (MX) diffraction experiments at synchrotrons use a single-axis goniometer. This markedly contrasts with small-molecule crystallography, in which the majority of the diffraction data are collected using multi-axis goniometers. A novel miniaturized κ-goniometer head, the MK3, has been developed to allow macromolecular crystals to be aligned. It is available on the majority of the structural biology beamlines at the ESRF, as well as elsewhere. In addition, the Strategy for the Alignment of Crystals (STAC) software package has been developed to facilitate the use of the MK3 and other similar devices. Use of the MK3 and STAC is streamlined by their incorporation into online analysis tools such as EDNA. The current use of STAC and MK3 on the MX beamlines at the ESRF is discussed. It is shown that the alignment of macromolecular crystals can result in improved diffraction data quality compared with data obtained from randomly aligned crystals.

  5. Purification, crystallization and preliminary X-ray diffraction experiment of nattokinase from Bacillus subtilis natto

    PubMed Central

    Yanagisawa, Yasuhide; Chatake, Toshiyuki; Chiba-Kamoshida, Kaori; Naito, Sawa; Ohsugi, Tadanori; Sumi, Hiroyuki; Yasuda, Ichiro; Morimoto, Yukio

    2010-01-01

    Nattokinase is a single polypeptide chain composed of 275 amino acids (molecular weight 27 724) which displays strong fibrinolytic activity. Moreover, it can activate other fibrinolytic enzymes such as pro-urokinase and tissue plasminogen activator. In the present study, native nattokinase from Bacillus subtilis natto was purified using gel-filtration chromatography and crystallized to give needle-like crystals which could be used for X-ray diffraction experiments. The crystals belonged to space group C2, with unit-cell parameters a = 74.3, b = 49.9, c = 56.3 Å, β = 95.2°. Diffraction images were processed to a resolution of 1.74 Å with an R merge of 5.2% (15.3% in the highest resolution shell) and a completeness of 69.8% (30.0% in the highest resolution shell). This study reports the first X-ray diffraction analysis of nattokinase. PMID:21139221

  6. Kagome staircase compound Co3V2O8 in an applied magnetic field: Single-crystal neutron diffraction study

    NASA Astrophysics Data System (ADS)

    Petrenko, O. A.; Wilson, N. R.; Balakrishnan, G.; Paul, D. Mck; McIntyre, G. J.

    2010-09-01

    The magnetic properties of Co3V2O8 have been studied by single-crystal neutron diffraction. In zero magnetic field, the observed broadening of the magnetic Bragg peaks suggests the presence of disorder both in the low-temperature ferromagnetic and in the higher temperature antiferromagnetic state. The field dependence of the intensity and position of the magnetic reflections in Co3V2O8 reveals a complex sequence of phase transitions in this Kagome staircase compound. For H∥a , a commensurate-incommensurate-commensurate transition is found in a field of 0.072 T in the antiferromagnetic phase at 7.5 K. For H∥c at low temperature, an applied field induces an unusual transformation from a ferromagnetic to an antiferromagnetic state at about 1 T accompanied by a sharp increase in magnetization.

  7. Magnetized laboratory plasma jets: experiment and simulation.

    PubMed

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 MA, 100 ns current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μm Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ∼1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μs current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics. PMID:25679726

  8. Magnetized laboratory plasma jets: Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 M A , 100 n s current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μ m Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ˜1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μ s current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics.

  9. New Developments at the XMaS Beamline For Magnetic and High Resolution Diffraction

    SciTech Connect

    Thompson, P.B.J.; Bouchenoire, L.; Brown, S.D.; Mannix, D.; Paul, D.F.; Lucas, C.; Kervin, J.; Cooper, M.J.; Arakawa, P.; Laughon, G.

    2004-05-12

    We report here on a number of developments that include enhancements of the sample environment on the XMaS beamline and the flux available at low energy. A 4 Tesla superconducting magnet has been designed to fit within the Euler cradle of a six circle Huber diffractometer, allowing scattering in both horizontal and vertical planes. The geometry of the magnet allows the application of longitudinal, transverse horizontal, and vertical fields. A further conventional magnet ({approx} 0.1 T) to minimize air absorption at low energies ({approx} 3KeV) has been designed for two circle applications, such as reflectivity. A novel in-vacuum slit screen has been developed, also minimizing absorption at low energies. New equipment for performing in-situ studies of surfaces in the electrochemical environment has been developed to allow control of the solution and sample temperature over the region of -5C to 80C. Preliminary experiments on the surface reconstructions of Au(111) in an electrolyte have been performed, whilst commissioning at the same time a MAR CCD detector for the beamline.

  10. Magnetic phases in the Kagomé staircase compound Co3V2O8 studied using powder neutron diffraction

    NASA Astrophysics Data System (ADS)

    Wilson, N. R.; Petrenko, O. A.; Chapon, L. C.

    2007-03-01

    The low temperature properties of the Kagomé-type system Co3V2O8 have been studied by powder neutron diffraction both in zero field and in applied magnetic fields of up to 8T . Below 6K , the zero-field ground state is ferromagnetic with the magnetic moments aligned along the a axis. The size of the moment on one of the two Co sites, the so-called cross-tie site, is considerably reduced compared to the fully polarized state. The application of a magnetic field in this phase is found to rapidly enhance the cross-tie site magnetic moment, which reaches the expected value of ˜3μB by the maximum applied field of 8T . Different reorientation behaviors are found for the Co cross-tie and spine sites, suggesting a more pronounced easy-axis anisotropy for moments on the spine sites. Rietveld refinements reveal that a simple model, where the spins on both cross-tie and spine sites rotate in the ac plane in a magnetic field, reproduces the experimental diffraction patterns well. In addition, it is found that at higher temperatures and moderate magnetic fields, the incommensurate antiferromagnetic order, corresponding to a transverse sinusoidal modulation above 8K , is suppressed to be replaced by ferromagnetic order.

  11. Magnetic Field Experiment Data Analysis System

    NASA Technical Reports Server (NTRS)

    Holland, D. B.; Zanetti, L. J.; Suther, L. L.; Potemra, T. A.; Anderson, B. J.

    1995-01-01

    The Johns Hopkins University Applied Physics Laboratory (JHU/APL) Magnetic Field Experiment Data Analysis System (MFEDAS) has been developed to process and analyze satellite magnetic field experiment data from the TRIAD, MAGSAT, AMPTE/CCE, Viking, Polar BEAR, DMSP, HILAT, UARS, and Freja satellites. The MFEDAS provides extensive data management and analysis capabilities. The system is based on standard data structures and a standard user interface. The MFEDAS has two major elements: (1) a set of satellite unique telemetry processing programs for uniform and rapid conversion of the raw data to a standard format and (2) the program Magplot which has file handling, data analysis, and data display sections. This system is an example of software reuse, allowing new data sets and software extensions to be added in a cost effective and timely manner. Future additions to the system will include the addition of standard format file import routines, modification of the display routines to use a commercial graphics package based on X-Window protocols, and a generic utility for telemetry data access and conversion.

  12. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Greenly, John; Gourdain, Pierre; Seyler, Charles; Blesener, Kate; Kusse, Bruce

    2013-10-01

    This research focuses on the initial ablation phase of a thing (20 micron) Al foil driven on the 1 MA-in-100 ns COBRA through a 5 mm diameter cathode in a radial configuration. In these experiments, ablated surface plasma (ASP) on the top of the foil and a strongly collimated axial plasma jet can be observed developing midway through current-rise. Our goal is to establish the relationship between the ASP and the jet. These jets are of interest for their potential relevance to astrophysical phenomena. An independently pulsed 200 μF capacitor bank with a Helmholtz coil pair allows for the imposition of a slow (150 μs) and strong (~1 T) axial magnetic field on the experiment. Application of this field eliminates significant azimuthal asymmetry in extreme ultraviolet emission of the ASP. This asymmetry is likely a current filamentation instability. Laser-backlit shadowgraphy and interferometry confirm that the jet-hollowing is correlated with the application of the axial magnetic field. Visible spectroscopic measurements show a doppler shift consistent with an azimuthal velocity in the ASP caused by the applied B-field. Computational simulations with the XMHD code PERSEUS qualitatively agree with the experimental results.

  13. Experiments in Nuclear Magnetic Resonance Microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Yong; Lu, Wei; Choi, J.-H.; Chia, H. J.; Mirsaidov, U. M.; Guchhait, S.; Cambou, A. D.; Cardenas, R.; Park, K.; Markert, J. T.

    2006-03-01

    We report our group's effort in the construction of an 8-T, ^3 He cryostat based nuclear magnetic resonance force microscope (NMRFM). The probe has two independent 3-D of piezoelectric x-y-z positioners for precise positioning of a fiber optic interferometer and a sample/gradient-producing magnet with respect to a micro-cantilever. The piezoelectric positioners have a very uniform controllable step size with virtually no backlash. A novel RF tuning circuit board design is implemented which allows us to simply swap out one RF component board with another for experiments involving different nuclear species. We successfully fabricated and are characterizing 50μm x50μm x0.2μm double torsional oscillators. We have also been characterizing ultrasoft cantilevers whose spring constant is on the order of 10-4 N/m. We also report NMRFM data for ammonium dihydrogen phosphate(ADP) at room temperature using our 1.2-T system. Observed features include the correct shift of the NMR peak with carrier frequency, increases in signal amplitude with both RF field strength and frequency modulation amplitude, and signal oscillation (spin nutation) as a function of tipping RF pulse length. Experiments in progress on NH4MgF3 (at 1.2 T) and MgB2 (at 8.1 T) will also be briefly reviewed. Robert A. Welch Foundation grant No.F-1191 and the National Science Foundation grant No. DMR-0210383.

  14. Single crystal neutron diffraction study of the magnetic structure of TmNi{sub 2}B{sub 2}C

    SciTech Connect

    Sternlieb, B.; Shapiro, S.; Stassis, C.; Goldman, A.I.; Canfield, P.

    1997-02-01

    Neutron diffraction techniques have been used to study the magnetic structure of single crystals of the magnetic superconductor (T{sub c} {congruent} 11K) TmNi{sub 2}B{sub 2}C. We find that below approximately 1.5K the magnetic moments order in an incommensurate spin wave with propagation vector q{sub m} = q{sub m} (a* +b*) (or q{sub m} = q{sub m} (a* + b*)) with q{sub m} = 0.094 {+-} 0.001. The spin wave is transverse with the moments aligned along the c-axis, and the observation of relatively intense higher order harmonics shows that the modulation is not purely sinusoidal but considerably squared. This incommensurate magnetic structure, which coexists with superconductivity below T{sub N} {congruent} 1.5K, is quite different from those observed in the magnetic superconductors HoNi{sub 2}B{sub 2}C and ErNi{sub 2}B{sub 2}C. The origin of diffraction peaks observed in scans parallel to a* is briefly discussed.

  15. Energy-dispersive neutron imaging and diffraction of magnetically driven twins in a Ni2MnGa single crystal magnetic shape memory alloy

    NASA Astrophysics Data System (ADS)

    Kabra, Saurabh; Kelleher, Joe; Kockelmann, Winfried; Gutmann, Matthias; Tremsin, Anton

    2016-09-01

    Single crystals of a partially twinned magnetic shape memory alloy, Ni2MnGa, were imaged using neutron diffraction and energy-resolved imaging techniques at the ISIS spallation neutron source. Single crystal neutron diffraction showed that the crystal produces two twin variants with a specific crystallographic relationship. Transmission images were captured using a time of flight MCP/Timepix neutron counting detector. The twinned and untwinned regions were clearly distinguishable in images corresponding to narrow-energy transmission images. Further, the spatially-resolved transmission spectra were used to elucidate the orientations of the crystallites in the different volumes of the crystal.

  16. Neutron Diffraction and Electrical Transport Studies on Magnetic Transition in Terbium at High Pressures and Low Temperatures

    NASA Astrophysics Data System (ADS)

    Thomas, Sarah; Montgomery, Jeffrey; Tsoi, Georgiy; Vohra, Yogesh; Weir, Samuel; Tulk, Christopher; Moreira Dos Santos, Antonio

    2013-06-01

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare earth metal terbium at high pressures and low temperatures in order to elucidate its transition from a helical antiferromagnetic to a ferromagnetic ordered phase as a function of pressure. The electrical resistance measurements using designer diamonds show a change in slope as the temperature is lowered through the ferromagnetic Curie temperature. The temperature of the ferromagnetic transition decreases at a rate of -16.7 K/GPa till 3.6 GPa, where terbium undergoes a structural transition from hexagonal close packed (hcp) to an α-Sm phase. Above this pressure, the electrical resistance measurements no longer exhibit a change in slope. In order to confirm the change in magnetic phase suggested by the electrical resistance measurements, neutron diffraction measurements were conducted at the SNAP beamline at the Oak Ridge National Laboratory. Measurements were made at pressures to 5.3 GPa and temperatures as low as 90 K. An abrupt increase in peak intensity in the neutron diffraction spectra signaled the onset of magnetic order below the Curie temperature. A magnetic phase diagram of rare earth metal terbium will be presented to 5.3 GPa and 90 K based on these studies.

  17. A Single-Crystal Neutron Diffraction Study on Magnetic Structure of the Quasi-One-Dimensional Antiferromagnet SrCo2V2O8

    NASA Astrophysics Data System (ADS)

    Juan-Juan, Liu; Jin-Chen, Wang; Wei, Luo; Jie-Ming, Sheng; Zhang-Zhen, He; A. Danilkin, S.; Wei, Bao

    2016-03-01

    The magnetic structure of the spin-chain antiferromagnet SrCo2V2O8 is determined by single-crystal neutron diffraction experiment. The system undergoes magnetic long range order below T_N = 4.96 K. The moment of 2.16{\\mu}_B per Co at 1.6 K in the screw chain running along the c axis alternates in the c-axis. The moments of neighboring screw chains are arranged antiferromagnetically along one in-plane axis and ferromagnetically along the other in-plane axis. This magnetic configuration breaks the 4-fold symmetry of the tetragonal crystal structure and leads to two equally populated magnetic twins with antiferromagnetic vector in the a or b axis. The very similar magnetic state to the isostructural BaCo2V2O8 warrants SrCo2V2O8 another interesting half-integer spin-chain antiferromagnet for investigation on quantum antiferromagnetism.

  18. Magnetic domain structure and crystallographic orientation of electrical steels revealed by a forescatter detector and electron backscatter diffraction.

    PubMed

    Gallaugher, Matthew; Brodusch, Nicolas; Gauvin, Raynald; Chromik, Richard R

    2014-07-01

    The magnetic properties of non-oriented electrical steels (NOES) are an important factor in determining the efficiency of electric vehicle drivetrains. Due to the highly variable texture of NOES, the relationships between crystal orientation, the magnetic domain structure, and the final magnetic properties are complicated and not fully understood. In this study, a NOES sample was characterized with a method capable of imaging surface magnetic domains using scanning electron microscopy (SEM) with an electron backscatter diffraction (EBSD) system equipped with a forescatter detector. This method used type II magnetic contrast without a specialized SEM setup, and imaged with a resolution limit of approximately 250-300nm. The domain structure of the NOES sample was successfully related to β, which was defined as the angle between the closest magnetic easy axis and the surface of the sample (the RD-TD plane). However, it was shown that if the easy axes were aligned between neighbouring grains with respect to the grain boundary normal, the domain structure could align with an easy axis that was not the closest to the surface, and complex domain structures could be become wider. This structure and width change of complex domain structures has not been previously observed from single crystal or large-grained material studies. The successful application of this method to reveal the influence of surrounding grains can be used to better understand the magnetic properties of NOES.

  19. Neutron diffraction studies and magnetism in Ti doped SrFeO{sub 3−δ} systems

    SciTech Connect

    Sendil Kumar, A.; Srinath, S.; Babu, P. D.

    2014-03-14

    The magnetic ground state of single phase tetragonal crystal structure with I4/mmm space group SrFe{sub 1−x}Ti{sub x}O{sub 3−δ} (x = 0.2 and 0.3) is investigated from 2 K to 300 K. Strong irreversibility is observed in zero-field-cooled (ZFC) and field-cooled DC magnetization curves. Arrott plots show the absence of spontaneous magnetization (M{sub S}) down to 2 K, ruling out the possibility of long range ferromagnetic order. Neutron diffraction measurements carried out at H = 0, 7 T (field cooled) at several temperatures above and below the T* (temperature at which M{sub ZFC}(T) is maximum) do not show any additional peaks and also no difference in intensity rules out, both the long range antiferromagnetic and ferromagnetic orders. Hence, the combined study of dc magnetization and neutron diffraction results reveals cluster spin glass behavior in SrFe{sub 1−x}Ti{sub x}O{sub 3−δ} (x = 0.2 and 0.3)

  20. Observation of diffractive orbits in the spectrum of excited NO in a magnetic field

    SciTech Connect

    Matzkin, A.; Raoult, M.; Gauyacq, D.

    2003-12-01

    We investigate the experimental spectrum of excited NO molecules in the diamagnetic regime and develop a quantitative semiclassical framework to account for the results. We show the dynamics can be interpreted in terms of classical orbits provided that in addition to the geometric orbits, diffractive effects are appropriately taken into account. We also show how individual orbits can be extracted from the experimental signal and use this procedure to reveal the first experimental manifestation of inelastic diffractive orbits.

  1. Structural and magnetic behavior of the cubic oxyfluoride SrFeO{sub 2}F studied by neutron diffraction

    SciTech Connect

    Thompson, Corey M.; Blakely, Colin K.; Flacau, Roxana; Greedan, John E.; Poltavets, Viktor V.

    2014-11-15

    The oxyfluoride SrFeO{sub 2}F has been prepared via a low temperature route involving the infinite-layer SrFeO{sub 2} and XeF{sub 2}. SrFeO{sub 2}F crystallizes in the cubic space group Pm-3m with disordered oxygen and fluorine atoms on the anion site. Recent reports demonstrated that SrFeO{sub 2}F is antiferromagnetic at room temperature and the zero field cooled and field cooled curves diverge at ∼150 K and ∼60 K, suggesting that the material has a spin glassy magnetic state at low temperatures. In this article, variable-temperature neutron diffraction (4–723 K) was performed to clarify the magnetic behavior observed in this material. Neutron powder diffraction measurements confirmed the antiferromagnetic (AFM) ordering of the system at room temperature. Below 710(1) K, the magnetic structure is a G-type AFM structure characterized by a propagation vector k=(1/2 , 1/2 , 1/2 ). The ordered moments on Fe{sup 3+} are 4.35(6)µ{sub B} at 4 K and 4.04(5)µ{sub B} at 290 K. Our results indicate that the cubic structure is retained all the way to base temperature (4 K) in contrast to PbFeO{sub 2}F. These results are compared with those of Pb and Ba analogs which exhibit very similar magnetic behavior. Furthermore, the observation of magnetic reflections at 4 K in the diffraction pattern shows the absence of the previously proposed spin glassy behavior at low temperatures. Previous proposals to explain the ZFC/FC divergences are examined. - Graphical abstract: Variable temperature powder neutron diffraction was employed to follow the evolution of the long range antiferromagnetic state in SrFeO{sub 2}F. - Highlights: • SrFeO{sub 2}F prepared via low temperature route involving SrFeO{sub 2} and XeF{sub 2}. • The cubic structure, Pm-3m, is retained at low temperatures, 4 K. • The magnetic structure is G-type AFM with T{sub N}=710 K and Fe{sup 3+} moment of 4.35µ{sub B}. • A small volume, bulk decoupled, spin glassy domain/cluster mechanism is proposed.

  2. Minimizing magnetic fields for precision experiments

    SciTech Connect

    Altarev, I.; Fierlinger, P.; Lins, T.; Marino, M. G.; Nießen, B.; Petzoldt, G.; Reisner, M.; Stuiber, S. Sturm, M.; Taggart Singh, J.; Taubenheim, B.; Rohrer, H. K.; Schläpfer, U.

    2015-06-21

    An increasing number of measurements in fundamental and applied physics rely on magnetically shielded environments with sub nano-Tesla residual magnetic fields. State of the art magnetically shielded rooms (MSRs) consist of up to seven layers of high permeability materials in combination with highly conductive shields. Proper magnetic equilibration is crucial to obtain such low magnetic fields with small gradients in any MSR. Here, we report on a scheme to magnetically equilibrate MSRs with a 10 times reduced duration of the magnetic equilibration sequence and a significantly lower magnetic field with improved homogeneity. For the search of the neutron's electric dipole moment, our finding corresponds to a 40% improvement of the statistical reach of the measurement. However, this versatile procedure can improve the performance of any MSR for any application.

  3. Magnetic field experiment on the Freja Satellite

    NASA Astrophysics Data System (ADS)

    Freja Magnetic Field Experiment Team

    1994-11-01

    Freja is a Swedish scientific satellite mission to study fine scale auroral processes. Launch was October 6, 1992, piggyback on a Chinese Long March 2C, to the present 600×1750 km, 63° inclination orbit. The JHU/APL provided the Magnetic Field Experiment (MFE), which includes a custom APL-designed Forth, language microprocessor. This approach has led to a truly generic and flexible design with adaptability to differing mission requirements and has resulted in the transfer of significant ground analysis to on-board processing. Special attention has been paid to the analog electronic and digital processing design in an effort to lower system noise levels, verified by inflight data showing unprecedented system noise levels for near-Earth magnetic field measurements, approaching the fluxgate sensor levels. The full dynamic range measurements are of the 3-axis Earth's magnetic field taken at 128 vector samples s-1 and digitized to 16 bit, resolution, primarily used to evaluate currents and the main magnetic field of the Earth. Additional 3-axis ‘AC’ channels are bandpass filtered from 1.5 to 128 Hz to remove the main field spin signal, the range is±650 nT. These vector measurements cover Pc waves to ion gyrofrequency magnetic wave signals up to the oxygen gyrofrequency (˜40 Hz). A separate, seventh channel samples the spin axis sensor with a bandpass filter of 1.5 to 256 Hz, the signal of which is fed to a software FFT. This on-board FFT processing covers the local helium gyrofrequencies (˜160 Hz) and is plotted in the Freja Summary Plots (FSPs) along with disturbance fields. First data were received in the U.S. October 16 from Kiruna, Sweden via the Internet and SPAN e-mail networks, and were from an orbit a few hours earlier over Greenland and Sweden. Data files and data products, e.g., FSPs generated at the Kiruna ground station, are communicated in a similar manner through an automatic mail distribution system in Stockholm to PIs and various users

  4. Density Limits in Toroidal Magnetic Confinement Experiments

    NASA Astrophysics Data System (ADS)

    Greenwald, Martin

    2001-10-01

    The density limit represents one of the fundamental operating boundaries for magnetic confinement devices - one with practical importance to the goal of fusion power. With fusion reactivity maximized at a plasma temperature on the order of 10 keV and a reaction rate scaling as n^2, an optimum density can be calculated which is not guaranteed to be achievable in any given device. Unlike operational limits for plasma current or pressure, the density limit cannot be explained by magneto-hydrodynamics alone. There is general agreement that the proximate cause for the disruptive limit in the tokamak is cooling of the plasma edge and subsequent current profile shrinkage. The edge cooling may be dominated by atomic physics processes or as suggested in recent experiments, by anomalous transport. A similar picture is emerging for the reversed field pinch (RFP), while the limit in stellarators is apparently due to loss of thermal equilibrium from radiation. Empirical scaling laws in which the maximum plasma density is proportional to the average current density have been fairly successful in predicting the limit for subsequent experiments. Surprisingly, the density limits found in tokamaks and RFPs are virtually identical. Currentless stellarators reach similar density limits, though the expression needs to be recast in terms of the rotational transform. While scaling laws have done a reasonable job in describing data from many recent experiments, they can only give hints at the underlying physics. Understanding the mechanism for the density limit is crucial for extrapolating machine performance into untested regimes and so far, a completely satisfactory theory has not emerged. It seems likely that robust, reliable predictions will only come from the development of a first-principles theory backed up by detailed experimental observations. The extensive work already accomplished and reviewed here should provide a solid basis for such development.

  5. Commensurate magnetic structures of RMn2O5 (R=Y,Ho,Bi) determined by single-crystal neutron diffraction

    NASA Astrophysics Data System (ADS)

    Vecchini, C.; Chapon, L. C.; Brown, P. J.; Chatterji, T.; Park, S.; Cheong, S.-W.; Radaelli, P. G.

    2008-04-01

    Precise magnetic structures of RMn2O5 , with R=Y,Ho,Bi in the commensurate and/or ferroelectric regime, have been determined by single-crystal neutron diffraction. For each system, the integrated intensities of a large number of independent magnetic Bragg reflections have been measured, allowing unconstrained least-squares refinement of the structures. The analysis confirms the previously reported magnetic configuration in the ab plane, in particular, the existence of zigzag antiferromagnetic chains. For the Y and Ho compounds, additional weak magnetic components parallel to the c axis were detected, which are modulated in phase quadrature with the a-b components. This component is extremely small in the BiMn2O5 sample, therefore supporting symmetric exchange as the principal mechanism inducing ferroelectricity. For HoMn2O5 , a magnetic ordering of the Ho moments was observed, which is consistent with a superexchange interaction through the oxygens. For all three compounds, the point symmetry in the magnetically ordered state is m2m , allowing the polar b axis found experimentally.

  6. Unconventional magnetic order in the frustrated diamond-lattice antiferromagnet CoAl2O4 studied by neutron diffraction and classical Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Zaharko, O.; Tóth, S.; Sendetskyi, O.; Cervellino, A.; Wolter-Giraud, A.; Dey, T.; Maljuk, A.; Tsurkan, V.

    2014-10-01

    CoAl2O4 spinel with magnetic Co2+ ions on the diamond lattice is known to be magnetically frustrated. We compare neutron single-crystal diffraction patterns measured in zero and applied magnetic fields with the ones obtained from classical Monte Carlo models. In simulations we test the influence of various parameters on diffraction patterns: the ratio of nearest-, J1, and next-nearest-, J2, neighbor interactions, magnetic field applied along the principal crystallographic directions, and random disorder on the A (Co2+) and B (Al3+) sites. We conclude that the models considered so far explain the broadening of magnetic Bragg peaks in zero magnetic field and their anisotropic response to applied magnetic field only partly. As bulk properties of our single crystal are isotropic, we suggest that its microstructure, specifically <111>-twin boundaries, could be a reason for the nonconventional magnetic order in CoAl2O4.

  7. Neutron diffraction and electrical transport studies on the incommensurate magnetic phase transition in holmium at high pressures

    SciTech Connect

    Thomas, Sarah; Uhoya, Walter; Tsoi, Georgiy; Wenger, Lowell E; Vohra, Yogesh; Chesnut, Gary Neal; Weir, S. T.; Tulk, Christopher A; Moreira Dos Santos, Antonio F

    2012-01-01

    Neutron diffraction and electrical transport measurements have been made on the heavy rare earth metal holmium at high pressures and low temperatures in order to elucidate its transition from a paramagnetic (PM) to a helical antiferromagnetic (AFM) ordered phase as a function of pressure. The electrical resistance measurements show a change in the resistance slope as the temperature is lowered through the antiferromagnetic Neel temperature. The temperature of this antiferromagnetic transition decreases from approximately 122 K at ambient pressure at a rate of -4.9 K GPa(-1) up to a pressure of 9 GPa, whereupon the PM-to-AFM transition vanishes for higher pressures. Neutron diffraction measurements as a function of pressure at 89 and 110 K confirm the incommensurate nature of the phase transition associated with the antiferromagnetic ordering of the magnetic moments in a helical arrangement and that the ordering occurs at similar pressures as determined from the resistance results for these temperatures.

  8. Neutron diffraction and electrical transport studies on the incommensurate magnetic phase transition in holmium at high pressures.

    PubMed

    Thomas, Sarah A; Uhoya, Walter O; Tsoi, Georgiy M; Wenger, Lowell E; Vohra, Yogesh K; Chesnut, Gary N; Weir, Samuel T; Tulk, Christopher A; dos Santos, Antonio M

    2012-05-30

    Neutron diffraction and electrical transport measurements have been made on the heavy rare earth metal holmium at high pressures and low temperatures in order to elucidate its transition from a paramagnetic (PM) to a helical antiferromagnetic (AFM) ordered phase as a function of pressure. The electrical resistance measurements show a change in the resistance slope as the temperature is lowered through the antiferromagnetic Néel temperature. The temperature of this antiferromagnetic transition decreases from approximately 122 K at ambient pressure at a rate of -4.9 K GPa(-1) up to a pressure of 9 GPa, whereupon the PM-to-AFM transition vanishes for higher pressures. Neutron diffraction measurements as a function of pressure at 89 and 110 K confirm the incommensurate nature of the phase transition associated with the antiferromagnetic ordering of the magnetic moments in a helical arrangement and that the ordering occurs at similar pressures as determined from the resistance results for these temperatures.

  9. Neutron diffraction and electrical transport studies on the incommensurate magnetic phase transition in holmium at high pressures

    NASA Astrophysics Data System (ADS)

    Thomas, Sarah A.; Uhoya, Walter O.; Tsoi, Georgiy M.; Wenger, Lowell E.; Vohra, Yogesh K.; Chesnut, Gary N.; Weir, Samuel T.; Tulk, Christopher A.; dos Santos, Antonio M.

    2012-05-01

    Neutron diffraction and electrical transport measurements have been made on the heavy rare earth metal holmium at high pressures and low temperatures in order to elucidate its transition from a paramagnetic (PM) to a helical antiferromagnetic (AFM) ordered phase as a function of pressure. The electrical resistance measurements show a change in the resistance slope as the temperature is lowered through the antiferromagnetic Néel temperature. The temperature of this antiferromagnetic transition decreases from approximately 122 K at ambient pressure at a rate of -4.9 K GPa-1 up to a pressure of 9 GPa, whereupon the PM-to-AFM transition vanishes for higher pressures. Neutron diffraction measurements as a function of pressure at 89 and 110 K confirm the incommensurate nature of the phase transition associated with the antiferromagnetic ordering of the magnetic moments in a helical arrangement and that the ordering occurs at similar pressures as determined from the resistance results for these temperatures.

  10. Neutron diffraction evidence for kinetic arrest of first order magneto-structural phase transitions in some functional magnetic materials.

    PubMed

    Siruguri, V; Babu, P D; Kaushik, S D; Biswas, Aniruddha; Sarkar, S K; Krishnan, Madangopal; Chaddah, P

    2013-12-11

    Neutron diffraction measurements, performed in the presence of an external magnetic field, have been used to show structural evidence for the kinetic arrest of the first order phase transition from (i) the high temperature austenite phase to the low temperature martensite phase in the magnetic shape memory alloy Ni37Co11Mn42.5Sn9.5, (ii) the higher temperature ferromagnetic phase to the lower temperature antiferromagnetic phase in the half-doped charge ordered compound La0.5Ca0.5MnO3 and (iii) the formation of glass-like arrested states in both compounds. The cooling and heating under unequal fields protocol has been used to establish phase coexistence of metastable and equilibrium states, and also to demonstrate the devitrification of the arrested metastable states in the neutron diffraction patterns. We also explore the field–temperature dependent kinetic arrest line TK(H), through the transformation of the arrested phase to the equilibrium phase. This transformation has been observed isothermally in reducing H, as also on warming in constant H. TK is seen to increase as H increases in both cases, consistent with the low-T equilibrium phase having lower magnetization.

  11. Structural phase transition and magnetism in hexagonal SrMnO{sub 3} by magnetization measurements and by electron, x-ray, and neutron diffraction studies

    SciTech Connect

    Daoud-Aladine, A.; Chapon, L. C.; Knight, K. S.; Martin, C.; Hervieu, M.; Brunelli, M.; Radaelli, P. G.

    2007-03-01

    The structural and magnetic properties of the hexagonal four-layer form of SrMnO{sub 3} have been investigated by combining magnetization measurements, electron diffraction, and high-resolution synchrotron x-ray and neutron powder diffraction. Below 350 K, there is subtle structural phase transition from hexagonal symmetry (space group P6{sub 3}/mmc) to orthorhombic symmetry (space group C222{sub 1}) where the hexagonal metric is preserved. The second-order phase transition involves a slight tilting of the corner-sharing Mn{sub 2}O{sub 9} units composed of two face-sharing MnO{sub 6} octahedra and the associated displacement of Sr{sup 2+} cations. The phase transition is described in terms of symmetry-adapted displacement modes of the high symmetry phase. Upon further cooling, long range magnetic order with propagation vector k=(0,0,0) sets in below 300 K. The antiferromagnetic structure, analyzed using representation theory, shows a considerably reduced magnetic moment indicating the crucial role played by direct exchange between Mn centers of the Mn{sub 2}O{sub 9} units.

  12. Remote Teaching Experiments on Magnetic Domains in Thin Films

    ERIC Educational Resources Information Center

    Dobrogowski, W.; Maziewski, A.; Zablotskii, V.

    2007-01-01

    We describe our experience in building a remote laboratory for teaching magnetic domains. Fulfilling the proposed on-line experiments, students can observe and study magnetization processes that are often difficult to explain with written material. It is proposed that networks of remotely accessible laboratories could be integrated in the Global…

  13. Neutron-Diffraction Evidence for the Ferrimagnetic Ground State of a Molecule-Based Magnet with Weakly Coupled Sublattices

    SciTech Connect

    Fishman, Randy Scott; Campo, Javier; Vos, Thomas E.; Miller, Joel S.

    2012-01-01

    The diruthenium compound [Ru2(O2CMe)4]3[Cr(CN)6] contains two weakly coupled, ferrimag- netically ordered sublattices occupying the same volume. The magnetic field Hc 800 Oe required to align the two sublattice moments is proportional to the antiferromagnetic dipolar interaction Kc B Hc 5 10 3 meV between sublattices. Powder neutron-diffraction measurements on a deuterated sample reveal that the sublattice moments are restricted by the anisotropy of the diruthenium paddle-wheel complexes to the cubic diagonals. Those measurements also suggest that the quantum corrections to the ground state are significant.

  14. Plants and Magnetism: Experiments with Biomagnetism

    ERIC Educational Resources Information Center

    McCormack, Alan J.

    1972-01-01

    Phenomenon of effect of magnetic field on plant growth provides wide opportunities for research in classrooms. Using moderately powerful magnets, seed growth patterns can be observed in pre-germination treatment, germination period exposure and under many other conditions. Such research may enable understanding magnetotropism more clearly. (PS)

  15. Characterization of thin-film multilayers using magnetization curves and modeling of low-angle X-ray diffraction data

    SciTech Connect

    Lane, M.; Chaiken, A.; Michel, R.P.

    1994-12-01

    We have characterized thin-film multilayers grown by ion-beam sputtering using magnetization curves and modeling of low-angle x-ray diffraction data. In our films, we use ferromagnetic layer = Co, Fe, and NiFe and spacer layer = Si, Ge, FeSi{sub 2}, and CoSi{sub 2}. We have studied the effects of (1) deposition conditions; (2) thickness of layers; (3) different layer materials; and (4) annealing. We find higher magnetization in films grown at 1000V rather than 500V and in films with spacer layers of 50{angstrom} rather than 100{angstrom}. We find higher coercivity in films with cobalt grown on germanium rather than silicon, metal grown on gold underlayers rather than on glass substrates, and when using thinner spacer layers. Finally, modeling reveals that films grown with disilicide layers are more thermally stable than films grown with silicon spacer layers.

  16. Electronically- and crystal-structure-driven magnetic structures and physical properties of RScSb (R = rare earth) compounds. A neutron diffraction, magnetization and heat capacity study

    SciTech Connect

    Ritter, C; Dhar, S K; Kulkarni, R; Provino, A; Paudyal, Durga; Manfrinetti, Pietro; Gschneidner, Karl A

    2014-08-14

    The synthesis of the new equiatomic RScSb ( R = La-Nd, Sm, Gd-Tm, Lu, Y) compounds has been recently reported. These rare earth compounds crystallize in two different crystal structures, adopting the CeScSi-type ( I 4/ mmm) for the lighter R (La-Nd, Sm) and the CeFeSi-type (P4 /nmm) structure for the heavier R ( R = Gd-Tm, Lu, Y). Here we report the results of neutron diffraction, magnetization and heat capacity measurements on some of these compounds ( R = Ce, Pr, Nd, Gd and Tb). Band structure calculations have also been performed on CeScSb and GdScGe (CeScSi-type), and on GdScSb and TbScSb (CeFeSi-type) to compare and understand the exchange interactions in CeScSi and CeFeSi structure types. The neutron diffraction investigation shows that all five compounds order magnetically, with the highest transition temperature of 66 K in TbScSb and the lowest of about 9 K in CeScSb. The magnetic ground state is simple ferromagnetic (τ = [0 0 0]) in CeScSb, as well in NdScSb for 32 >T > 22 K. Below 22 K a second magnetic transition, with propagation vector τ = [¼ ¼ 0], appears in NdScSb. PrScSb has a magnetic structure within, determined by mostly ferromagnetic interactions and antiferromagnetic alignment of the Pr-sites connected through the I-centering ( τ = [1 0 0]). A cycloidal spiral structure with a temperature dependent propagation vector τ = [δ δ ½] is found in TbScSb. The results of magnetization and heat capacity lend support to the main conclusions derived from neutron diffraction. As inferred from a sharp peak in magnetization, GdScSb orders antiferromagnetically at 56 K. First principles calculations show lateral shift of spin split bands towards lower energy from the Fermi level as the CeScSi-type structure changes to the CeFeSi-type structure. This rigid shift may force the system to transform from exchange split ferromagnetic state to the antiferromagnetic state in RScSb compounds (as seen for example in GdScSb and TbScSb) and is proposed to

  17. Producing acoustic 'Frozen Waves': simulated experiments with diffraction/attenuation resistant beams in lossy media.

    PubMed

    Prego-Borges, José L; Zamboni-Rached, Michel; Recami, Erasmo; Costa, Eduardo Tavares

    2014-08-01

    The so-called Localized Waves (LW), and the "Frozen Waves" (FW), have raised significant attention in the areas of Optics and Ultrasound, because of their surprising energy localization properties. The LWs resist the effects of diffraction for large distances, and possess an interesting self-reconstruction -self-healing- property (after obstacles with size smaller than the antenna's); while the FWs, a sub-class of LWs, offer the possibility of arbitrarily modeling the longitudinal field intensity pattern inside a prefixed interval, for instance 0⩽z⩽L, of the wave propagation axis. More specifically, the FWs are localized fields "at rest", that is, with a static envelope (within which only the carrier wave propagates), and can be endowed moreover with a high transverse localization. In this paper we investigate, by simulated experiments, various cases of generation of ultrasonic FW fields, with the frequency of f0=1 MHz in a water-like medium, taking account of the effects of attenuation. We present results of FWs for distances up to L=80 mm, in attenuating media with absorption coefficient α in the range 70⩽α⩽170 dB/m. Such simulated FW fields are constructed by using a procedure developed by us, via appropriate finite superpositions of monochromatic ultrasonic Bessel beams. We pay due attention to the selection of the FW parameters, constrained by the rather tight restrictions imposed by experimental Acoustics, as well as to some practical implications of the transducer design. The energy localization properties of the Frozen Waves can find application even in many medical apparatus, such as bistouries or acoustic tweezers, as well as for treatment of diseased tissues (in particular, for the destruction of tumor cells, without affecting the surrounding tissues; also for kidney stone shuttering, etc.).

  18. Experience with the SLC permanent magnet multipoles

    SciTech Connect

    Gross, G.; Spencer, J.

    1994-06-01

    Permanent magnets have been used in the SLC Damping Rings and their injection and extraction lines since 1985. Recent upgrades of the DR vacuum chambers provided an opportunity to check DR magnets prior to higher beam current operation. Several PM sextupoles downstream of the injection kickers in the electron ring had exceeded their thermal stabilization values of 80{degrees}C and some showed serious mechanical deformations and radiation >1 R at contact. We discuss our observations, measurements and a few inexpensive modifications that should improve these magnets under such conditions. A new, block matching algorithm allowed us to use magnet blocks that had been considered unusable because of very different remament field strengths and easy axis errors.

  19. Prospective of ultradispersic magnetic particles in biological experiments in microgravity

    NASA Astrophysics Data System (ADS)

    Nechitailo, Galina S.; Kuznetsov, Anatoli; Malashin, S.

    All organisms on Earth use gravity for their lifecycles. Microgravity disturbs the lifecycles significantly: orientation ability is damaged, thermo and mass exchange processes are changed, adaptation mechanisms are destroyed. A recovering the normal life cycle of organism in future long-term mission requires an artificial gravity which is complicate and not realistic with present technologies. We propose to use a magnetic properties of the biological objects for recovering of the gravity-dependent biological processes in organism during space flight. Based on result of magnetic properties investigation in gravity-sensitive plant cells, we have prepared and carried out the experiments on space station MIR. For the experiments, Magnitogravistat device was designed and installed on the station. The aim of the experiment was to replace a gravity factor of plant with a magnetic factor. The magnetic effect is based on the fact, that a magnetic particle of V volume is under the force F=ΔæVHgradH in the magnetic gradient gradH, where Δæ is the difference between the magnetic susceptibility of particle and media. When the particles are placed into the cell, the cell can be managed by the magnetic field. In laboratory experiment the iron-carbon particles of 1-2 um with nanostructurised surface and high adsorption properties have been used. The particles can be suspended in water and adsorbed chemicals including cell metabolites. In strong magnetic field, the particles can be agglomerated and the liquid substrate can be replaced. The local magnetic field near the particles can influence on cell processes. The magnetic field causes a cell differentiation and can influence on cell proliferation. A new space experiment with magnetic particles is planned to get a knowledge on cell influence and to improve a cell metabolism.

  20. Magnetization distribution in the tetragonal Ba(Fe1-xCox)2As2, x=0.066 probed by polarized neutron diffraction

    NASA Astrophysics Data System (ADS)

    Prokeš, K.; Gukasov, A.; Argyriou, D. N.; Bud'ko, S. L.; Canfield, P. C.; Kreyssig, A.; Goldman, A. I.

    2011-02-01

    Polarized neutron diffraction has been performed on a tetragonal Ba(Fe1-xCox)2As2, x=0.066 single crystal under an applied magnetic field of 6 T directed along the [\\overline{1}10 ] direction to determine the magnetic structure factors of various Bragg reflections. The maximum entropy reconstruction based on bulk magnetization measurements and polarized neutron diffraction data reveal a small induced magnetic moment residing on the 4d Wyckoff site that is occupied by Fe/Co atoms. No significant magnetization density has been found on the Ba and As atomic positions. The small polarizability of Fe/Co sites leads to flipping ratios very close to 1.00. Our data suggest a non-zero orbital contribution to the Fe/Co magnetic form factor in good agreement with recent theoretical and experimental studies.

  1. Diffractive stacks of metamaterial lattices with a complex unit cell: Self-consistent long-range bianisotropic interactions in experiment and theory

    NASA Astrophysics Data System (ADS)

    Kwadrin, Andrej; Koenderink, A. Femius

    2014-01-01

    Metasurfaces and metamaterials promise arbitrary rerouting of light using two-dimensional (2D) planar arrangements of electric and magnetic scatterers, respectively, 3D stacks built out of such 2D planes. An important problem is how to self-consistently model the response of these systems in a manner that retains dipole intuition yet does full justice to the self-consistent multiple scattering via near-field and far-field retarded interactions. We set up such a general model for metamaterial lattices of complex 2D unit cells of poly-atomic basis as well as allowing for stacking in a third dimension. In particular, each scatterer is quantified by a magnetoelectric polarizability tensor and Ewald lattice summation deals with all near-field and long-range retarded electric, magnetic, and magnetoelectric couplings self-consistently. We show in theory and experiment that grating diffraction orders of dilute split ring lattices with complex unit cells show a background-free signature of magnetic dipole response. For denser lattices experiment and theory show that complex unit cells can reduce the apparent effect of bianisotropy, i.e., the strong oblique-incidence handed response that was reported for simple split ring lattices. Finally, the method is applied to calculate transmission of finite stacks of lattices. Thereby our simple methodology allows us to trace the emergence of effective material constants when building a 3D metamaterial layer by layer, as well as facilitating the design of metasurfaces.

  2. Results from the RAT Magnet Experiment on Spirit and Opportunity

    NASA Astrophysics Data System (ADS)

    Goetz, Walter; Hviid, S. F.; Madsen, M. B.; Kinch, K. M.; Leer, K.; Gunnlauggson, H. P.

    2006-09-01

    The Rock Abrasion Tool (RAT) is one of the four payload elements that are mounted to the end of the robotic arm onboard the Mars Exploration Rovers (MER). The RAT is a mechanism that can grind circular depressions several millimeters into the Martian rocks. The RAT magnet experiment is composed of four permanent magnets of different strengths built into the revolve housing cap plate of the RAT. Magnetic material liberated by the grinding process will be attracted by these magnets. At Gusev crater 14 different grindings were performed over 416 sols. During grinding into rocks in the plains (Adirondack, Humphrey, Mazatzal) a substantial amount of homogeneous, dark-gray material accumulated on the magnets. Based on data from the Mössbauer (MB) spectrometer the rocks are known to contain the magnetic material (Ti) magnetite. During grindings into the Eagle crater outcrop at Meridiani Planum strongly magnetic material was captured by the RAT magnets. The material is reddish and appears to be largely homogeneous. The total amount of collected material is slightly smaller as compared to the RAT magnet experiment on Spirit. Also no strongly magnetic, iron containing mineral phase has been identified by MB spectroscopy. Based on Pancam observations of the RAT magnets as well as other data we suggest that the Meridiani outcrops contains < 0.5 wt.% of a ferrimagnetic phase, possibly partly oxidized magnetite.

  3. Experiences with making diffraction image data available: what metadata do we need to archive?

    SciTech Connect

    Kroon-Batenburg, Loes M. J.; Helliwell, John R.

    2014-10-01

    A local raw ‘diffraction data images’ archive was made available and some data sets were retrieved and reprocessed, which led to analysis of the anomalous difference densities of two partially occupied Cl atoms in cisplatin as well as a re-evaluation of the resolution cutoff in these diffraction data. General questions on storing raw data are discussed. It is also demonstrated that often one needs unambiguous prior knowledge to read the (binary) detector format and the setup of goniometer geometries. Recently, the IUCr (International Union of Crystallography) initiated the formation of a Diffraction Data Deposition Working Group with the aim of developing standards for the representation of raw diffraction data associated with the publication of structural papers. Archiving of raw data serves several goals: to improve the record of science, to verify the reproducibility and to allow detailed checks of scientific data, safeguarding against fraud and to allow reanalysis with future improved techniques. A means of studying this issue is to submit exemplar publications with associated raw data and metadata. In a recent study of the binding of cisplatin and carboplatin to histidine in lysozyme crystals under several conditions, the possible effects of the equipment and X-ray diffraction data-processing software on the occupancies and B factors of the bound Pt compounds were compared. Initially, 35.3 GB of data were transferred from Manchester to Utrecht to be processed with EVAL. A detailed description and discussion of the availability of metadata was published in a paper that was linked to a local raw data archive at Utrecht University and also mirrored at the TARDIS raw diffraction data archive in Australia. By making these raw diffraction data sets available with the article, it is possible for the diffraction community to make their own evaluation. This led to one of the authors of XDS (K. Diederichs) to re-integrate the data from crystals that supposedly

  4. Status of Magnetic Nozzle and Plasma Detachment Experiment

    SciTech Connect

    Chavers, D. Gregory; Dobson, Chris; Jones, Jonathan; Lee, Michael; Martin, Adam; Gregory, Judith; Cecil, Jim; Bengtson, Roger D.; Breizman, Boris; Arefiev, Alexey; Chang-Diaz, Franklin; Squire, Jared; Glover, Tim; McCaskill, Greg; Cassibry, Jason; Li Zhongmin

    2006-01-20

    High power plasma propulsion can move large payloads for orbit transfer, lunar missions, and beyond with large savings in fuel consumption owing to the high specific impulse. At high power, lifetime of the thruster becomes an issue. Electrodeless devices with magnetically guided plasma offer the advantage of long life since magnetic fields confine the plasma radially and keep it from impacting the material surfaces. For decades, concerns have been raised about the plasma remaining attached to the magnetic field and returning to the vehicle along the closed magnetic field lines. Recent analysis suggests that this may not be an issue if the magnetic field is properly shaped in the nozzle region and the plasma has sufficient energy density to stretch the magnetic field downstream. An experiment is being performed to test the theory regarding the MHD detachment scenario. The status of that experiment will be discussed in this paper.

  5. New generation of cryogen free advanced superconducting magnets for neutron scattering experiments

    NASA Astrophysics Data System (ADS)

    Kirichek, O.; Brown, J.; Adroja, D. T.; Manuel, P.; Kouzmenko, G.; Bewley, R. I.; Wotherspoon, R.

    2012-12-01

    Recent advances in superconducting technology and cryocooler refrigeration have resulted in a new generation of advanced superconducting magnets for neutron beam applications. These magnets have outstanding parameters such as high homogeneity and stability at highest magnetic fields possible, a reasonably small stray field, low neutron scattering background and larger exposure to neutron detectors. At the same time the pulse tube refrigeration technology provides a complete re-condensing regime which allows to minimise the requirements for cryogens without introducing additional noise and mechanical vibrations. The magnets can be used with dilution refrigerator insert which expands the temperature range from 20mK to 300K. Here we are going to present design, test results and the operational data of the 14T magnet for neutron diffraction and the 9T wide angle chopper magnet for neutron spectroscopy developed by Oxford Instruments in collaboration with ISIS neutron source. First scientific results obtained from the neutron scattering experiments with these magnets are also going to be discussed.

  6. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment.

    PubMed

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H; Hruszkewycz, Stephan O

    2016-09-01

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifying in situ chamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load. PMID:27577782

  7. Utilizing broadband X-rays in a Bragg coherent X-ray diffraction imaging experiment.

    PubMed

    Cha, Wonsuk; Liu, Wenjun; Harder, Ross; Xu, Ruqing; Fuoss, Paul H; Hruszkewycz, Stephan O

    2016-09-01

    A method is presented to simplify Bragg coherent X-ray diffraction imaging studies of complex heterogeneous crystalline materials with a two-stage screening/imaging process that utilizes polychromatic and monochromatic coherent X-rays and is compatible with in situ sample environments. Coherent white-beam diffraction is used to identify an individual crystal particle or grain that displays desired properties within a larger population. A three-dimensional reciprocal-space map suitable for diffraction imaging is then measured for the Bragg peak of interest using a monochromatic beam energy scan that requires no sample motion, thus simplifying in situ chamber design. This approach was demonstrated with Au nanoparticles and will enable, for example, individual grains in a polycrystalline material of specific orientation to be selected, then imaged in three dimensions while under load.

  8. Six-axis multi-anvil press for high-pressure, high-temperature neutron diffraction experiments

    SciTech Connect

    Sano-Furukawa, A. Hattori, T.; Arima, H.; Yamada, A.; Tabata, S.; Kondo, M.; Nakamura, A.; Kagi, H.; Yagi, T.

    2014-11-15

    We developed a six-axis multi-anvil press, ATSUHIME, for high-pressure and high-temperature in situ time-of-flight neutron powder diffraction experiments. The press has six orthogonally oriented hydraulic rams that operate individually to compress a cubic sample assembly. Experiments indicate that the press can generate pressures up to 9.3 GPa and temperatures up to 2000 K using a 6-6-type cell assembly, with available sample volume of about 50 mm{sup 3}. Using a 6-8-type cell assembly, the available conditions expand to 16 GPa and 1273 K. Because the six-axis press has no guide blocks, there is sufficient space around the sample to use the aperture for diffraction and place an incident slit, radial collimators, and a neutron imaging camera close to the sample. Combination of the six-axis press and the collimation devices realized high-quality diffraction pattern with no contamination from the heater or the sample container surrounding the sample. This press constitutes a new tool for using neutron diffraction to study the structures of crystals and liquids under high pressures and temperatures.

  9. Simple Experiments on Magnetism and Electricity...from Edison.

    ERIC Educational Resources Information Center

    Schultz, Robert F.

    Background information, lists of materials needed and procedures used are provided for 16 simple experiments on electricity and magnetism. These experiments are organized into sections dealing with: (1) Edison's carbon experiments (building a galvanometer, investigating the variable conductivity of carbon, and examining the carbon transmitter…

  10. Spin frustration in M{sup II}[C(CN){sub 3}]{sub 2} (M = V, Cr). A magnetism and neutron diffraction

    SciTech Connect

    Manson, J.L.; Ressouche, E.; Miller, J.S.

    2000-03-20

    Three-dimensional coordination network solids of M{sup II}[C(CN){sub 3}]{sub 2} (M = V, Cr) composition possess interpenetrating rutile-like network structures. Each [C(CN){sub 3}]{sup {minus}} bonds to three different metal ions in a triangular array, affording a geometrical topology akin to a Kagome lattice leading to competing spin exchange interactions and spin frustration. The crystal and magnetic structure of Cr{sup II}[C(CN){sub 3}] was determined by Rietveld refinement of the powder neutron diffraction data at 2 and 15 K and belongs to the orthorhombic space group Pmna [a = 7.313(1) {angstrom}, b = 5.453(1) {angstrom}, c = 10.640(1) {angstrom}, Z = 2, T = 15 K]. Each Cr{sup II} has a tetragonally elongated octahedral structure with four Cr-N(1) distances of 2.077(2) {angstrom} and two significantly longer axial Cr-N(2) distances of 2.452(2) {angstrom}. Magnetic susceptibility measurements between 1.7 and 300 K reveal strong antiferromagnetic interactions for both V- and Cr[C(CN){sub 3}]{sub 2} with {theta} = {minus}67 and {minus}46 K, respectively, from a fit to the Curie-Weiss law. Long-range magnetic ordering does not occur for M = V above 1.7 K, in contrast to M = Cr, which antiferromagnetically orders at low temperature. This is attributed to Jahn-Teller distorted Cr{sup II} sites relieving frustration in one dimension, leading to 2-D Ising antiferromagnetism, as observed by both magnetic susceptibility and specific heat studies. Neutron diffraction experiments at 2 K for Cr[C(CN){sub 3}]{sub 2} yielded additional Bragg reflections as a result of antiferromagnetic ordering with the moments on the Cr{sup II} atoms aligned parallel to c and 4.7(1) {micro}{sub B}. Fitting of the magnetic order parameter to a power law yielded T{sub N} = 6.12(4) K and {beta} = 0.18(1) consistent with 2-D Ising behavior. A T{sub N} of 6.13 K is also observed from the specific heat data.

  11. Diffractive light trapping in crystal-silicon films: experiment and electromagnetic modeling.

    PubMed

    Weiss, Dirk N; Lee, Benjamin G; Richmond, Dustin A; Nemeth, William; Wang, Qi; Keszler, Douglas A; Branz, Howard M

    2011-10-10

    Diffractive light trapping in 1.5 μm thick crystal silicon films is studied experimentally through hemispherical reflection measurements and theoretically through rigorous coupled-wave analysis modeling. The gratings were fabricated by nanoimprinting of dielectric precursor films. The model data, which match the experimental results well without the use of any fitting parameters, are used to extract the light trapping efficiency. Diffractive light trapping is studied as a function of incidence angle, and an enhancement of light absorption is found for incidence angles up to 50° for both TE and TM polarizations.

  12. The magnetic phase diagram of the UAs 1- xSe x system studied by neutron diffraction from single crystals

    NASA Astrophysics Data System (ADS)

    Kuznietz, M.; Burlet, P.; Rossat-Mignod, J.; Vogt, O.

    1987-10-01

    The magnetic phase diagram of the UAs 1- xSe x system (temperature versus composition) has been determined from neutron diffraction measurements in zero applied magnetic field on single crystals with x=0.03, 0.05, 0.10, 0.20, 0.25, 0.30, 0.40 and 0.50, as well as from measurements in finite applied magnetic fields on single crystals with x=0.10, 0.20, 0.25 and 0.30. For x⩽0.40 an incommensurate magnetic ordering ( k=[0,0, k]; mk ∥ k) develops below TN down to TIC. The k- value at TN decreases with the increase of x; in decreasing temperatures the k-value approaches the commensurate value below TIC. At TIC an incommensurate-commensurate transition leads to the type-I phase ( k=1) for x ⩽0.05 (with a subsequent transition to type-IA at TO), to the type-IA phase ( k= {1}/{2}) for 0.05 ⩽ x⩽ 0.30, and to the squaring-up of the (5+,4-) phase ( k≈0.244) for x=0.40 below T≈90 K. For x⩽0.50 the ordering is ferromagnetic. The nature of the multi- k structure is determined from measurements in finite fields. With the previously established single- k structure of type-I (in UAs), the UAs 1- xSe x system exhibits single- k, double- k and triple- k structures. A double- k-triple- k transition occurs for x ≈0.15 in the type-IA phase and for x≈0.22 in the incommensurate phase. The ordered magnetic moment at T=4.2 K is practically independent of the ordering ( m≈2μ B).

  13. Experiments with a Magnetically Controlled Pendulum

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2007-01-01

    A magnetically controlled pendulum is used for observing free and forced oscillations, including nonlinear oscillations and chaotic motion. A data-acquisition system stores the data and displays time series of the oscillations and related phase plane plots, Poincare maps, Fourier spectra and histograms. The decay constant of the pendulum can be…

  14. Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

    PubMed

    Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

    2016-04-01

    We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed. PMID:26964007

  15. Dynamic nuclear polarization in a magnetic resonance force microscope experiment.

    PubMed

    Issac, Corinne E; Gleave, Christine M; Nasr, Paméla T; Nguyen, Hoang L; Curley, Elizabeth A; Yoder, Jonilyn L; Moore, Eric W; Chen, Lei; Marohn, John A

    2016-04-01

    We report achieving enhanced nuclear magnetization in a magnetic resonance force microscope experiment at 0.6 tesla and 4.2 kelvin using the dynamic nuclear polarization (DNP) effect. In our experiments a microwire coplanar waveguide delivered radiowaves to excite nuclear spins and microwaves to excite electron spins in a 250 nm thick nitroxide-doped polystyrene sample. Both electron and proton spin resonance were observed as a change in the mechanical resonance frequency of a nearby cantilever having a micron-scale nickel tip. NMR signal, not observable from Curie-law magnetization at 0.6 T, became observable when microwave irradiation was applied to saturate the electron spins. The resulting NMR signal's size, buildup time, dependence on microwave power, and dependence on irradiation frequency was consistent with a transfer of magnetization from electron spins to nuclear spins. Due to the presence of an inhomogeneous magnetic field introduced by the cantilever's magnetic tip, the electron spins in the sample were saturated in a microwave-resonant slice 10's of nm thick. The spatial distribution of the nuclear polarization enhancement factor ε was mapped by varying the frequency of the applied radiowaves. The observed enhancement factor was zero for spins in the center of the resonant slice, was ε = +10 to +20 for spins proximal to the magnet, and was ε = -10 to -20 for spins distal to the magnet. We show that this bipolar nuclear magnetization profile is consistent with cross-effect DNP in a ∼10(5) T m(-1) magnetic field gradient. Potential challenges associated with generating and using DNP-enhanced nuclear magnetization in a nanometer-resolution magnetic resonance imaging experiment are elucidated and discussed.

  16. How Rosalind Franklin Discovered the Helical Structure of DNA: Experiments in Diffraction

    ERIC Educational Resources Information Center

    Braun, Gregory; Tierney, Dennis; Schmitzer, Heidrun

    2011-01-01

    Rosalind Franklin, a chemical physicist (1920-1958), used x-ray diffraction to determine the structure of DNA. What exactly could she read out from her x-ray pattern, shown in Fig. 1? In lecture notes dated November 1951, R. Franklin wrote the following: "The results suggest a helical structure (which must be very closely packed) containing 2, 3…

  17. Crystallization of porcine pancreatic elastase and a preliminary neutron diffraction experiment

    SciTech Connect

    Kinoshita, Takayoshi; Tamada, Taro; Imai, Keisuke; Kurihara, Kazuo; Ohhara, Takashi; Tada, Toshiji; Kuroki, Ryota

    2007-04-01

    To investigate the structural characteristics of a covalent inhibitor bound to porcine pancreatic elastase (PPE), including H atoms and hydration by water, a crystal of porcine pancreatic elastase with its inhibitor was grown to a size of 1.6 mm{sup 3} for neutron diffraction study. The crystal diffracted to 2.3 Å resolution with sufficient quality for further structure determination owing to the similar atomic scattering properties of deuterium and carbon. Porcine pancreatic elastase (PPE) resembles the attractive drug target leukocyte elastase, which has been implicated in a number of inflammatory disorders. In order to investigate the structural characteristics of a covalent inhibitor bound to PPE, including H atoms and the hydration by water, a single crystal of PPE for neutron diffraction study was grown in D{sub 2}O containing 0.2 M sodium sulfate (pD 5.0) using the sitting-drop vapour-diffusion method. The crystal was grown to a size of 1.6 mm{sup 3} by repeated macroseeding. Neutron diffraction data were collected at room temperature using a BIX-3 diffractometer at the JRR-3 research reactor of the Japan Atomic Energy Agency (JAEA). The data set was integrated and scaled to 2.3 Å resolution in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 51.2, b = 57.8, c = 75.6 Å.

  18. Experiences with making diffraction image data available: what metadata do we need to archive?

    PubMed Central

    Kroon-Batenburg, Loes M. J.; Helliwell, John R.

    2014-01-01

    Recently, the IUCr (International Union of Crystallography) initiated the formation of a Diffraction Data Deposition Working Group with the aim of developing standards for the representation of raw diffraction data associated with the publication of structural papers. Archiving of raw data serves several goals: to improve the record of science, to verify the reproducibility and to allow detailed checks of scientific data, safeguarding against fraud and to allow reanalysis with future improved techniques. A means of studying this issue is to submit exemplar publications with associated raw data and metadata. In a recent study of the binding of cisplatin and carboplatin to histidine in lysozyme crystals under several conditions, the possible effects of the equipment and X-ray diffraction data-processing software on the occupancies and B factors of the bound Pt compounds were compared. Initially, 35.3 GB of data were transferred from Manchester to Utrecht to be processed with EVAL. A detailed description and discussion of the availability of metadata was published in a paper that was linked to a local raw data archive at Utrecht University and also mirrored at the TARDIS raw diffraction data archive in Australia. By making these raw diffraction data sets available with the article, it is possible for the diffraction community to make their own evaluation. This led to one of the authors of XDS (K. Diederichs) to re-integrate the data from crystals that supposedly solely contained bound carboplatin, resulting in the analysis of partially occupied chlorine anomalous electron densities near the Pt-binding sites and the use of several criteria to more carefully assess the diffraction resolution limit. General arguments for archiving raw data, the possibilities of doing so and the requirement of resources are discussed. The problems associated with a partially unknown experimental setup, which preferably should be available as metadata, is discussed. Current thoughts on

  19. Experiences with making diffraction image data available: what metadata do we need to archive?

    PubMed

    Kroon-Batenburg, Loes M J; Helliwell, John R

    2014-10-01

    Recently, the IUCr (International Union of Crystallography) initiated the formation of a Diffraction Data Deposition Working Group with the aim of developing standards for the representation of raw diffraction data associated with the publication of structural papers. Archiving of raw data serves several goals: to improve the record of science, to verify the reproducibility and to allow detailed checks of scientific data, safeguarding against fraud and to allow reanalysis with future improved techniques. A means of studying this issue is to submit exemplar publications with associated raw data and metadata. In a recent study of the binding of cisplatin and carboplatin to histidine in lysozyme crystals under several conditions, the possible effects of the equipment and X-ray diffraction data-processing software on the occupancies and B factors of the bound Pt compounds were compared. Initially, 35.3 GB of data were transferred from Manchester to Utrecht to be processed with EVAL. A detailed description and discussion of the availability of metadata was published in a paper that was linked to a local raw data archive at Utrecht University and also mirrored at the TARDIS raw diffraction data archive in Australia. By making these raw diffraction data sets available with the article, it is possible for the diffraction community to make their own evaluation. This led to one of the authors of XDS (K. Diederichs) to re-integrate the data from crystals that supposedly solely contained bound carboplatin, resulting in the analysis of partially occupied chlorine anomalous electron densities near the Pt-binding sites and the use of several criteria to more carefully assess the diffraction resolution limit. General arguments for archiving raw data, the possibilities of doing so and the requirement of resources are discussed. The problems associated with a partially unknown experimental setup, which preferably should be available as metadata, is discussed. Current thoughts on

  20. Long-time stability of a low-energy electron diffraction spin polarization analyzer for magnetic imaging.

    PubMed

    Lofink, F; Hankemeier, S; Frömter, R; Kirschner, J; Oepen, H P

    2012-02-01

    The time stability of a polarization analyzer that is used for imaging of magnetic structures in a scanning electron microscope with spin polarization analysis (spin-SEM or SEMPA) is investigated. The detector is based on the diffraction of low-energy electrons at a W(100) crystal at 104.5 eV (LEED detector). Due to the adsorption of hydrogen from residual gas, a change of the scattering conditions is found that causes an angular shift of the LEED beams as well as changes of intensity. The quality factor, which describes the efficiency of the detector in SEMPA application, however, is found to be almost constant up to a hydrogen coverage of θ ≈ 0.25. This gives stable working conditions within roughly 1 h at vacuum conditions of 10(-10) mbar.

  1. Modeling HEDLA magnetic field generation experiments on laser facilities

    NASA Astrophysics Data System (ADS)

    Fatenejad, M.; Bell, A. R.; Benuzzi-Mounaix, A.; Crowston, R.; Drake, R. P.; Flocke, N.; Gregori, G.; Koenig, M.; Krauland, C.; Lamb, D.; Lee, D.; Marques, J. R.; Meinecke, J.; Miniati, F.; Murphy, C. D.; Park, H.-S.; Pelka, A.; Ravasio, A.; Remington, B.; Reville, B.; Scopatz, A.; Tzeferacos, P.; Weide, K.; Woolsey, N.; Young, R.; Yurchak, R.

    2013-03-01

    The Flash Center is engaged in a collaboration to simulate laser driven experiments aimed at understanding the generation and amplification of cosmological magnetic fields using the FLASH code. In these experiments a laser illuminates a solid plastic or graphite target launching an asymmetric blast wave into a chamber which contains either Helium or Argon at millibar pressures. Induction coils placed several centimeters away from the target detect large scale magnetic fields on the order of tens to hundreds of Gauss. The time dependence of the magnetic field is consistent with generation via the Biermann battery mechanism near the blast wave. Attempts to perform simulations of these experiments using the FLASH code have uncovered previously unreported numerical difficulties in modeling the Biermann battery mechanism near shock waves which can lead to the production of large non-physical magnetic fields. We report on these difficulties and offer a potential solution.

  2. Oscillations of a dipole in a magnetic field: An experiment

    NASA Astrophysics Data System (ADS)

    Bisquert, Juan; Hurtado, Emilia; Mafé, Salvador; Pina, José

    1990-09-01

    The small oscillations of a parallelepidal magnet along the axis of a circular coil carrying an electric current have been analyzed theoretically and experimentally. The study of this system (a particular case of a magnetic dipole in motion in a nonuniform magnetic field) involves basic ideas from both mechanics and electromagnetism, and the equipment used in the experiment is very common in an undergraduate laboratory. Comparison with the experiment shows that a very simple theoretical approach gives good results. It is also shown how the introduction of some refinements in the physical model can improve the agreement between theory and experiment, though the theoretical analysis becomes more involved in this case. The use of the principle of superposition to calculate magnetic fields is emphasized throughout the article.

  3. Dichroic Coherent Diffractive Imaging

    NASA Astrophysics Data System (ADS)

    Tripathi, Ashish

    Understanding electronic structure at nanometer resolution is crucial to understanding physics such as phase separation and emergent behavior in correlated electron materials. Nondestructive probes which have the ability to see beyond surfaces on nanometer length and sub-picosecond time scales can greatly enhance our understanding of these systems and will impact development of future technologies, such as magnetic storage. Polarized x-rays are an appealing choice of probe due to their penetrating power, elemental and magnetic specificity, and high spatial resolution. The resolution of traditional x-ray microscopy is limited by the nanometer precision required to fabricate x-ray optics. In this thesis, a novel approach to lensless imaging of an extended magnetic nanostructure is presented. We demonstrate this approach by imaging ferrimagnetic "maze" domains in a Gd/Fe multilayer with perpendicular anisotropy. A series of dichroic coherent diffraction patterns, ptychographically recorded, are numerically inverted using non-convex and non-linear optimization theory, and we follow the magnetic domain configuration evolution through part of its magnetization hysteresis loop by applying an external magnetic field. Unlike holographic methods, it does not require a reference wave or precision optics, and so is a far simpler experiment. In addition, it enables the imaging of samples with arbitrarily large spatial dimensions, at a spatial resolution limited solely by the coherent x-ray flux and wavelength. It can readily be extended to other non-magnetic systems that exhibit circular or linear dichroism. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of the new generation of phenomenally brilliant x-ray sources.

  4. Zigzag type magnetic structure of the spin J eff = ½ compound α-RuCl3 as determined by neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Ritter, C.

    2016-09-01

    Using high intensity powder neutron diffraction the magnetic structure of a-RuCl3 has been determined. Following the magnetic propagation vector κ = (½, 0, ½) the J eff = ½ spins of Ru3+ adopt a Zigzag type arrangement on the honeycomb lattice of the layered P3112 structure. The magnetic moments are oriented perpendicular to the trigonal axis. Similarities and differences to previously published single crystal data are discussed. The low value of the magnetic moments, μRu = 0.5(1) μB indicates a possible closeness of α-RuCl3 to the Kitaev spin liquid state.

  5. Change in the magnetic structure of (Bi,Sm)FeO{sub 3} thin films at the morphotropic phase boundary probed by neutron diffraction

    SciTech Connect

    Maruyama, Shingo; Anbusathaiah, Varatharajan; Takeuchi, Ichiro; Fennell, Amy; Enderle, Mechthild; Ratcliff, William D.

    2014-11-01

    We report on the evolution of the magnetic structure of BiFeO{sub 3} thin films grown on SrTiO{sub 3} substrates as a function of Sm doping. We determined the magnetic structure using neutron diffraction. We found that as Sm increases, the magnetic structure evolves from a cycloid to a G-type antiferromagnet at the morphotropic phase boundary, where there is a large piezoelectric response due to an electric-field induced structural transition. The occurrence of the magnetic structural transition at the morphotropic phase boundary offers another route towards room temperature multiferroic devices.

  6. The photoelectric effect and study of the diffraction of light: Two new experiments in UNILabs virtual and remote laboratories network

    NASA Astrophysics Data System (ADS)

    Pedro Sánchez, Juan; Sáenz, Jacobo; de la Torre, Luis; Carreras, Carmen; Yuste, Manuel; Heradio, Rubén; Dormido, Sebastián

    2016-05-01

    This work describes two experiments: "study of the diffraction of light: Fraunhofer approximation" and "the photoelectric effect". Both of them count with a virtual, simulated, version of the experiment as well as with a real one which can be operated remotely. The two previous virtual and remote labs (built using Easy Java(script) Simulations) are integrated in UNILabs, a network of online interactive laboratories based on the free Learning Management System Moodle. In this web environment, students can find not only the virtual and remote labs but also manuals with related theory, the user interface description for each application, and so on.

  7. Crystal structure and magnetism of YbFeMnO 5: A neutron diffraction and Mössbauer spectroscopy study

    NASA Astrophysics Data System (ADS)

    Martínez-Lope, M. J.; Retuerto, M.; Alonso, J. A.; García-Hernández, M.; Krezhov, K.; Spirov, I.; Ruskov, T.; Fernández-Díaz, M. T.

    2009-04-01

    We have studied the crystal structure and magnetic properties of Y bFeMnO 5 obtained by substituting Fe 3+ for Mn 3+ in the parent Y bMn 2O 5 compound, through x-ray (XRD) and neutron (NPD) powder diffraction, magnetometry and Mössbauer spectroscopy. The samples were prepared in polycrystalline form by a soft chemistry route, followed by thermal treatments under high-oxygen pressure. The Rietveld analysis of diffraction data shows that Y bFeMnO 5 is isostructural with the oxides of stoichiometry RMn 2O 5 (R=rare earth, Y or Bi); the crystal structure is orthorhombic, Pbam space group, formed by chains of edge-sharing Mn 4+O 6 octahedra linked together by dimer groups of square pyramids Fe 3+O 5 and Y b 3+O 8 scalenohedra. A low level of disorder was established between the two transition metal positions 4 f and 4 h, occupied ideally by Mn 4+ and by Fe 3+: about 6% of Mn cations is replaced by Fe and 16% of Fe by Mn. Mössbauer spectroscopy data confirm the existence of two distinct crystallographic sites for Fe 3+. One of them corresponds to almost regular octahedra (at 4 f positions), characterized by nearly equal Mn/Fe-O distances of 1.890 Å at RT (from NPD data), giving a quadrupole doublet in the Mössbauer spectra at RT, broadened by the Fe/Mn disorder over this site. The second environment for Fe 3+ contributes to a less broadened, but more intensive doublet in the Mössbauer spectra, which corresponds to a distorted square pyramid Fe 3+O 5 (at 4h sites), for which NPD data demonstrates an axial distortion with three sets of Fe-O distances at 2.010(2) Å, 1.859(5) Å and 1.925(3) Å. Magnetic studies and the thermal evolution of the NPD patterns show that below a transition temperature Tc˜178 K a long-range magnetic order is developed, resolved from NPD data as a ferrimagnetic structure with propagation vector k=0. The spin arrangements for the Mn 4+ ions ( 4f site) and Fe 3+ ions ( 4h site) are given by the basis vectors ( 0,0,Fz) and ( 0,0,Fz

  8. Operational experience with superconducting synchrotron magnets

    SciTech Connect

    Martin, P.S.

    1987-03-01

    The operational experience with the Fermilab Tevatron is presented, with emphasis on reliability and failure modes. Comprisons are made between the operating efficiencies for the superconducting machine and for he conventional Main Ring.

  9. Order/disorder phenomena in Zn1-xMnxGa2Se4 ordered vacancy compounds: high temperature neutron powder diffraction experiments

    NASA Astrophysics Data System (ADS)

    Alonso-Gutiérrez, P.; Morón, M. C.; Hull, S.; Sanjuán, M. L.

    2013-12-01

    We present a study of order-disorder phenomena in the series of tetrahedral ordered vacancy compounds Zn1-xMnxGa2Se4 by means of time-of-flight neutron diffraction at high temperature together with dc magnetic susceptibility, Raman spectroscopy, differential thermal analysis and optical absorption experiments. Samples of nominal composition x = 0, 0.24, 0.5, 0.77 and 1 have been studied. An order-disorder phase transition has been detected, with Tc ranging from 472 to 610 ° C, which involves a structural change from a defect chalcopyrite phase, with I\\bar {4} space group (s.g.) and three different cation sites, to a partially disordered defect stannite, in which Zn, Mn and half of the Ga ions share the 4d site in I\\bar {4}2 m s.g. Neither the vacancies nor the Ga ions occupying site 2a are involved in the phase transition. An additional ordering process is observed on approaching the phase transition from below, which is attributed to several factors: the activation of cation diffusion at ˜300 ° C, the partially disordered cation distribution exhibited by the as-grown single crystals and the preference of Mn atoms for the 2d crystallographic site in the I\\bar {4} structure. The reversibility of the phase transition is analysed with the aid of magnetic, optical and Raman experiments.

  10. Neutron diffraction studies on structural and magnetic properties of RE{sub 2}NiGe{sub 3} (RE=La, Ce)

    SciTech Connect

    Kalsi, Deepti; Rayaprol, S.; Siruguri, V.; Peter, Sebastian C.

    2014-09-15

    We report the crystallographic properties of RE{sub 2}NiGe{sub 3} (RE=La, Ce) synthesized by arc melting. Rietveld refinement on the powder neutron diffraction (ND) data suggest both compounds are isostructural and crystallize in the non-centrosymmetric Er{sub 2}RhSi{sub 3} type structure having hexagonal space group P6{sup ¯}2c. In the crystal structure of RE{sub 2}NiGe{sub 3}, two dimensional arrangements of nickel and germanium atoms lead to the formation of hexagonal layers with rare earth atoms sandwiched between them. Magnetic susceptibility measurements performed in low fields exhibit antiferromagnetic ordering in cerium compound around (T{sub o}=) 3.2 K. Neutron diffraction measurements at 2.8 K (i.e., at Tdiffraction lines nor indicate the appearance of any new diffraction lines in the Q-range of 0.47–7.34 Å{sup −1}, thus ruling out any long-range magnetic order. - Graphical abstract: The compounds La{sub 2}NiGe{sub 3} and Ce{sub 2}NiGe{sub 3} crystallize in the Er{sub 2}RhSi{sub 3} type. Magnetic susceptibility show antiferromagnetic ordering for Ce{sub 2}NiGe{sub 3} at 3.2 K and neutron diffraction confirms the absence of long range ordering. - Highlights: RE{sub 2}NiGe{sub 3} (RE=La, Ce) crystallize in the ordered superstructure of the AlB{sub 2} type. Magnetic susceptibility measurements exhibit antiferromagnetic ordering in Ce{sub 2}NiGe{sub 3}. Structure and magnetism of RE{sub 2}NiGe{sub 3} (RE=La, Ce) are studied by neutron diffraction.

  11. Simulations of a Johann/Johansson diffraction spectrometer for x-ray experiments at an electron beam ion source

    NASA Astrophysics Data System (ADS)

    Jabłoński, Ł.; Jagodziński, P.; Banaś, D.; Pajek, M.

    2013-09-01

    The ray tracing simulations of x-ray spectra for a compact six-crystal Johann/Johansson diffraction spectrometer covering a wide photon energy range (70 eV-15 keV), i.e. from the extended ultraviolet to the hard x-ray region, are discussed in the context of x-ray experiments at an electron beam ion source facility. In particular, the x-ray line profiles and energy resolution for different diffraction crystals and multilayers were studied, and the effects of extension of x-ray source size and misalignment were investigated. The simulations were also performed for x-ray emission from solid targets bombarded by electrons, which will be used for calibration of the x-ray spectrometer.

  12. Diffraction and forward physics results of the ATLAS experiment from the Run I

    SciTech Connect

    Taševský, Marek

    2015-04-10

    Various aspects of forward physics have been studied by the ATLAS collaboration using data from Run I at the LHC. In this text, main results of four published analyses are summarized, all based on data from proton-proton collisions at √(s)=7 TeV collected in 2010 or 2011. Two analyses deal with the diffractive signature, one based on single-sided events, the other on large rapidity gaps in soft events. In addition, a recent measurement of the total pp cross section using the ALFA subdetector and a recent study of higher-order QCD effects using a jet veto are discussed.

  13. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2008-04-01

    The interaction of shock waves with inhomogeneous media is important in many astrophysical problems, e.g. the role of shock compression in star formation. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory, to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. Experiments with flyer-generated shock waves have been performed on the Z machine in Sandia. The Zebra accelerator at the Nevada Terawatt Facility (NTF) allows for complementary experiments with high repetition rate. First experiments on Zebra demonstrated flyer acceleration to sufficiently high velocities (around 2 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  14. Experiment to measure fast ion transport by magnetic fluctuations

    NASA Astrophysics Data System (ADS)

    Preiwisch, Adam; Heidbrink, William; Boehmer, Heinz; McWilliams, Roger; Carter, Troy; Gekelman, Walter; Tripathi, Shreekrishna; van Compernolle, Bart; Vincena, Steve

    2013-10-01

    Fast ion transport in a linear magnetic field is studied at the upgraded Large Plasma Device. Recent developments allow for the generation of turbulent magnetic flux ropes, produced by a hot LaB6 cathode situated in the main chamber.1 A large-gyroradius, energetic lithium ion beam (300 <= Efast /Ti <= 1000) is passed through the turbulent region and collected by a collimated analyzer downstream, yielding a detailed plane profile of the fast ion distribution.2 Magnetic fluctuations, density, and temperature profiles are also obtained via probes. Enhanced fast-ion transport is clearly observed in the form of beam broadening. Early analysis shows broadband ion saturation current and magnetic fluctuations attributed to the flux ropes. A follow up experiment is currently under way to address whether the increased transport is primarily attributed to magnetic fields, associated electric fields, or increased Coulomb scattering.

  15. Experimental magnetic form factors in Co3V2O8 : A combined study of ab initio calculations, magnetic Compton scattering, and polarized neutron diffraction

    NASA Astrophysics Data System (ADS)

    Qureshi, N.; Zbiri, M.; Rodríguez-Carvajal, J.; Stunault, A.; Ressouche, E.; Hansen, T. C.; Fernández-Díaz, M. T.; Johnson, M. R.; Fuess, H.; Ehrenberg, H.; Sakurai, Y.; Itou, M.; Gillon, B.; Wolf, Th.; Rodríguez-Velamazan, J. A.; Sánchez-Montero, J.

    2009-03-01

    We present a combination of ab initio calculations, magnetic Compton scattering, and polarized neutron experiments, which elucidate the density distribution of unpaired electrons in the kagome staircase system Co3V2O8 . Ab initio wave functions were used to calculate the spin densities in real and momentum spaces, which show good agreement with the respective experiments. It has been found that the spin polarized orbitals are equally distributed between the t2g and the eg levels for the spine (s) Co ions while the eg orbitals of the cross-tie (c) Co ions only represent 30% of the atomic spin density. Furthermore, the results reveal that the magnetic moments of the cross-tie Co ions, which are significantly smaller than those of the spine Co ions in the zero-field ferromagnetic structure, do not saturate by applying an external magnetic field of 2 T along the easy axis a . In turn, the increasing bulk magnetization, which can be observed by field dependent macroscopic measurements, originates from induced magnetic moments on the O and V sites. The refined individual magnetic moments are μ(Coc)=1.54(4)μB , μ(Cos)=2.87(3)μB , μ(V)=0.41(4)μB , μ(O1)=0.05(5)μB , μ(O2)=0.35(5)μB , and μ(O3)=0.36(5)μB combining to the same macroscopic magnetization value, which was previously only attributed to the Co ions.

  16. EM Induction Experiment to Determine the Moment of a Magnet

    ERIC Educational Resources Information Center

    Najiya Maryam, K. M.

    2014-01-01

    If we drop a magnet through a coil, an emf is induced in the coil according to Faraday's law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets.…

  17. Crystallization and preliminary neutron diffraction experiment of human farnesyl pyrophosphate synthase complexed with risedronate.

    PubMed

    Yokoyama, Takeshi; Ostermann, Andreas; Mizuguchi, Mineyuki; Niimura, Nobuo; Schrader, Tobias E; Tanaka, Ichiro

    2014-04-01

    Nitrogen-containing bisphosphonates (N-BPs), such as risedronate and zoledronate, are currently used as a clinical drug for bone-resorption diseases and are potent inhibitors of farnesyl pyrophosphate synthase (FPPS). X-ray crystallographic analyses of FPPS with N-BPs have revealed that N-BPs bind to FPPS with three magnesium ions and several water molecules. To understand the structural characteristics of N-BPs bound to FPPS, including H atoms and hydration by water, neutron diffraction studies were initiated using BIODIFF at the Heinz Maier-Leibnitz Zentrum (MLZ). FPPS-risedronate complex crystals of approximate dimensions 2.8 × 2.5 × 1.5 mm (∼3.5 mm(3)) were obtained by repeated macro-seeding. Monochromatic neutron diffraction data were collected to 2.4 Å resolution with 98.4% overall completeness. Here, the first successful neutron data collection from FPPS in complex with N-BPs is reported.

  18. Using mobile camera for a better exploitation and understanding of interference and diffraction experiments

    NASA Astrophysics Data System (ADS)

    Ben Lakhdar, Z.; Dhaouadi, Z.; Ghalila, H.; Lahmar, S.; Majdi, Y.

    2009-06-01

    To deduce the wave nature of light, explain its behavior when it interacts with material obstacles (diffraction) or its behavior when light from two coherent sources interfere with each other (interference), we need to explain what are waves and what are their properties (wavelength, frequency, mathematical relationship between wavelength and frequency, superposition principle, …). Two principal approaches are generally used to introduce waves: 1/ An experimental approach (the example commonly used approach): to observe the water waves pattern obtained when drops of water (with an eye dropper, two eye droppers, or equivalent) fall -at a steady rate- on a calm pool of water surface. 2/ A theoretical approach: Wave coming from one source is represented by a sinusoidal function; Superposition of waves coming from two coherent sources is done by a sum of two sinusoidal functions with constant phase difference. In Tunisia, different workshops on "wave nature of light based on interference and diffraction" using Active Learning process have been organized for about 150 secondary school teachers in 2009. These workshops are based on UNESCO Active Learning in Optics and Photonics (ALOP) project. This paper will show how taking water wave's pattern using some participant's mobile camera helps to make some misconceptions resolved and includes at the same time other more complex phenomena.

  19. Neutron powder diffraction investigation of magnetic structure and spin reorientation transition of HoFe1-xCrxO3 solid solutions

    NASA Astrophysics Data System (ADS)

    Liu, Xinzhi; Hao, Lijie; Liu, Yuntao; Ma, Xiaobai; Meng, Siqin; Li, Yuqing; Gao, Jianbo; Guo, Hao; Han, Wenze; Sun, Kai; Wu, Meimei; Chen, Xiping; Xie, Lei; Klose, Frank; Chen, Dongfeng

    2016-11-01

    Orthoferrite solid solution HoFe1-xCrxO3 (x=0, 0.2,…,1.0) was synthesized via solid state reaction methods. The crystal structure, magnetism and spin reorientation properties of this system were investigated by X-ray diffraction, neutron powder diffraction and magnetic measurements. For compositions of x≤0.6, the system exhibits similar magnetic properties to HoFeO3. With increasing Cr-doping, the system adopts a Γ4(GxAyFz) magnetic configuration with a decreased Neel temperature from 640 K to 360 K. A Γ42 spin reorientation of Fe(Cr)3+ was also observed in this system with an increase in transition temperature from 56 K to about 200 K due to competition between the Fe(Cr)-Fe(Cr) and Ho-Fe(Cr) interactions. For the x≥0.8, the system behaves more like HoCrO3 which adopts a Γ2(FxCyGz) configuration with no spin reorientation below the Neel temperature TN. Throughout the whole substitution range, we found that the saturated moment of Fe(Cr) was less than the ideal value for a free ion, which implies the existence of spin fluctuation in this system. A systematic magnetic structure variation with Cr-substitution is revealed by Rietveld refinement. A phase diagram combining the results of the magnetic measurements and neutron powder diffraction results was obtained.

  20. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, S.; Ford, J.; Wright, S.; Martinez, D.; Plechaty, C.; Presura, R.

    2009-08-01

    Many astrophysical phenomena involve the interaction of a shock wave with an inhomogeneous background medium. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. First experiments on Zebra at the Nevada Terawatt Facility (NTF) have demonstrated flyer acceleration to sufficiently high velocities (up to 5 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  1. Detrital magnetizations from redeposition experiments of different natural sediments

    NASA Astrophysics Data System (ADS)

    Spassov, Simo; Valet, Jean-Pierre

    2012-10-01

    We carried out several experiments with carbonate-rich and clay-rich sediments that were redeposited in plastic cubes or in 1-meter-long cylindrical tubes with the aim of investigating the sensitivity of the depositional remanent magnetization (DRM) to various environmental and physical parameters. In contrast to previous studies, we did not observe any difference in the DRM acquired with or without saline water for either kind of sediment. Taking advantage of a gelatin that fixes the position of particles in suspension, we were able to measure the magnetization of suspended sediments within water-filled columns and thus to test the degree of alignment of magnetic grains. The magnetization of clay-rich sediments was not far from saturation but the magnetization was considerably reduced after deflocculation because the large flocs that favored alignment of magnetic grains were destroyed by the deflocculant. Similarly, the large flocs found at the bottom of the deposition tubes also reveal an efficient magnetic alignment. In contrast, the weak magnetization of the carbonate-rich sediments with small flocs yielded accurate and well-grouped magnetization directions that were not sensitive to deflocculation. Only a fraction of magnetic grains was mechanically oriented by the field in this case because of the weak net magnetic moments of the grains embedded within small flocs. The DRM was constrained by redeposition in plastic cubes performed without gelatin and with different field intensities. The DRM intensity of the carbonate-rich sediments is linearly related to field strength, which attests to their suitability for studies of relative paleointensity. Tests performed with mud from several stratigraphic levels in different marine sediment cores failed to reveal a significant influence of carbonate content on DRM, which suggests a relatively minor role of lithological changes on records of relative paleointensity.

  2. Exploring the complex magnetic phase diagram of Ce2PdGe3 : A neutron powder diffraction and μ SR study

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, A.; Ritter, C.; Adroja, D. T.; Coomer, F. C.; Strydom, A. M.

    2016-07-01

    The magnetic state of the tetragonal compound Ce2PdGe3 , which crystallizes in the space group P 42/m m c , a derivative of the α -ThSi2 structure, has been investigated by magnetic susceptibility, heat capacity, muon spin relaxation (μ SR ), and neutron diffraction measurements. Heat capacity data indicate two separate magnetic phase transitions at TN1=10.7 K and TN 2=2.3 K. The presence of bulk long-range magnetic order is confirmed by our μ SR study below 11 K, where a drop of nearly 2/3 in the muon initial asymmetry and a sharp increase in the muon depolarization rate were observed. Neutron powder diffraction reveals that only one out of two Ce sites becomes magnetically ordered with magnetic propagation vector κ =(0 ) at TN1,adopting an antiferromagnetic arrangement of magnetic moments μCe3+=1.78 (1 ) μB along the c axis. At TN 2 the second Ce site orders similarly, following the same magnetic propagation vector κ =(0 ) , showing, however, at the same time a significant ferromagnetic component within the tetragonal basal plane. A second propagation vector, κ =(1/2 ,0 ,1/2 ) , appears concomitantly at TN 2.

  3. Magnetoelastics of a spin liquid : x-ray diffraction studies of Tb{sub 2}Ti{sub 2}O{sub 7} in pulsed magnetic fields.

    SciTech Connect

    Ruff, J. P. C.; Islam, Z.; Clancy, J. P.; Ross, K. A.; Nojiri, H.; Matsuda, Y. H.; Dabkowska, H. A.; Dabkowski, A. D.; Gaulin, B. D.; X-Ray Science Division; McMaster Univ.; Tohoku Univ.; Univ. of Tokyo; Canadian Inst. for Advanced Research; Brockhouse Inst. for Materials Research

    2010-08-13

    We report high resolution single crystal x-ray diffraction measurements of the frustrated pyrochlore magnet Tb{sub 2}Ti{sub 2}O{sub 7}, collected using a novel low temperature pulsed magnet system. This instrument allows characterization of structural degrees of freedom to temperatures as low as 4.4 K, and in applied magnetic fields as large as 30 T. We show that Tb{sub 2}Ti{sub 2}O{sub 7} manifests intriguing structural effects under the application of magnetic fields, including strongly anisotropic giant magnetostriction, a restoration of perfect pyrochlore symmetry in low magnetic fields, and ultimately a structural phase transition in high magnetic fields. It is suggested that the magnetoelastic coupling thus revealed plays a significant role in the spin liquid physics of Tb{sub 2}Ti{sub 2}O{sub 7} at low temperatures.

  4. An Electromagnetic Drift Instability in the Magnetic Reconnection Experiment (MRX) and its Importance for Magnetic Reconnection

    SciTech Connect

    Russell Kulsrud; Hantao Ji; Will Fox; Masaaki Yamada

    2005-06-07

    The role which resistivity plays in breaking magnetic field lines, heating the plasma, and plasma field slippage during magnetic reconnection is discussed. Magnetic fluctuations are observed in the MRX (Magnetic Reconnection Experiment) that are believed to provide resistive friction or wave resistivity. A localized linear theory has been proposed for their origin as an obliquely propagating Lower Hybrid Drift Instability. In this paper, the linear theory of the instability is summarized, and the resulting heating and slippage are calculated from quasi-linear theory. Making use of measured amplitudes of the magnetic fluctuations in the MRX the amount of these effects is estimated. Within the experimental uncertainties they are shown to be quite important for the magnetic reconnection process.

  5. An electromagnetic drift instability in the magnetic reconnection experiment and its importance for magnetic reconnection

    SciTech Connect

    Kulsrud, Russell; Ji Hantao; Fox, William; Yamada, Masaaki

    2005-08-15

    The role which resistivity plays in breaking magnetic field lines, heating the plasma, and plasma-field slippage during magnetic reconnection is discussed. Magnetic fluctuations are observed in the MRX (magnetic reconnection experiment) [M. Yamada, H. Ji, S. Hsu, T. Carter, R. Kulsrud, N. Bertz, F. Jobes, Y. Ono, and F. Perkins, Phys. Plasmas 4, 1936 (1997)] that are believed to provide resistive friction or wave resistivity. A localized linear theory has been proposed for their origin as an obliquely propagating lower hybrid drift instability. In this paper, the linear theory of the instability is summarized, and the resulting heating and slippage are calculated from quasilinear theory. Making use of measured amplitudes of the magnetic fluctuations in the MRX, the amount of these effects is estimated. Within the experimental uncertainties they are shown to be quite important for the magnetic reconnection process.

  6. The resonant X-ray diffraction in Co-Akermanite: Theory and experiment

    SciTech Connect

    Bindi, L.; Dmitrienko, V. E.; Ovchinnikova, E. N.; Soedzhima, Yu.

    2006-12-15

    The structural factors for X-ray resonant diffraction near the K-absorption edge of cobalt in Co-akermanite have been calculated with allowance for the known data about its incommensurate 2D modulation. It is shown that the local symmetry of Co atoms in the basic structure does not allow any pure resonant reflections in the dipole-dipole approximation. However, pure resonant reflections of the h00 (h = 2n + 1) type are possible owing to the dipole-quadrupole contribution. The 5D formalism is used for the incommensurately modulated structure. It is shown that the displacement terms in the anisotropic tensor atomic factors could mainly contribute to the first-order satellites, providing pure resonant satellite reflections of the hhlm0 (m = 2n + 1) or h00mm-bar (h = 2n + 1) types.

  7. Resolving rainbows with superimposed diffraction oscillations in NO + rare gas scattering: experiment and theory

    NASA Astrophysics Data System (ADS)

    Onvlee, Jolijn; Vogels, Sjoerd N.; van der Avoird, Ad; Groenenboom, Gerrit C.; van de Meerakker, Sebastiaan Y. T.

    2015-05-01

    A Stark decelerator is used in combination with velocity map imaging to study collisions of NO radicals with rare gas atoms in a counterpropagating crossed beam geometry. This powerful combination of techniques results in scattering images with extremely high resolution, in which rotational and L-type rainbows with superimposed quantum mechanical diffraction oscillations are visible. The experimental data are in excellent agreement with quantum mechanical scattering calculations. Furthermore, hard-shell models and a partial wave analysis are used to clarify the origin of the various structures that are visible. A specific feature is found for NO molecules colliding with Ar atoms that is extremely sensitive to the precise shape of the potential energy surface. Its origin is explained in terms of interfering partial waves with very high angular momentum, corresponding to trajectories with large impact parameters.

  8. Experimenting with magnetism: Ways of learning of Joann and Faraday

    NASA Astrophysics Data System (ADS)

    Cavicchi, Elizabeth

    1997-09-01

    This paper narrates learning as it evolved through experimental work and interpretation in two distinct investigations: the explorations of permanent magnets and needles conducted by a student, Joann, as I interactively interviewed her, and Faraday's initial experimenting with diamagnetism, as documented in his Diary. Both investigators puzzled over details, revisited their confusions resiliently, and invented analogies as ways of extending their questioning; "misconceptions" and conflict were not explicit to their process. Additionally, Faraday formed interpretations—and doubts critiquing them—that drew upon his extensive experience with magnetism's spatial behaviors. These two cases suggest that physics instruction could include opportunities for students' development of their own investigatory learning.

  9. HiSPoD: a program for high-speed polychromatic X-ray diffraction experiments and data analysis on polycrystalline samples.

    PubMed

    Sun, Tao; Fezzaa, Kamel

    2016-07-01

    A high-speed X-ray diffraction technique was recently developed at the 32-ID-B beamline of the Advanced Photon Source for studying highly dynamic, yet non-repeatable and irreversible, materials processes. In experiments, the microstructure evolution in a single material event is probed by recording a series of diffraction patterns with extremely short exposure time and high frame rate. Owing to the limited flux in a short pulse and the polychromatic nature of the incident X-rays, analysis of the diffraction data is challenging. Here, HiSPoD, a stand-alone Matlab-based software for analyzing the polychromatic X-ray diffraction data from polycrystalline samples, is described. With HiSPoD, researchers are able to perform diffraction peak indexing, extraction of one-dimensional intensity profiles by integrating a two-dimensional diffraction pattern, and, more importantly, quantitative numerical simulations to obtain precise sample structure information.

  10. Local magnetic moments in a dinuclear Co{sup 2+} complex as seen by polarized neutron diffraction:Beyond the effective spin-(1/2) model

    SciTech Connect

    Borta, Ana; Luneau, Dominique; Jeanneau, Erwann; Gillon, Beatrice; Gukasov, Arsen; Cousson, Alain; Ciumacov, Iurii; Sakiyama, Hiroshi; Tone, Katsuya; Mikuriya, Masahiro

    2011-05-01

    Polarized neutron diffraction investigations of a paramagnetic molecular dinuclear Co{sup 2+} complex, using the local site susceptibility method, show that the Co{sup 2+} ions carry opposite magnetic moments of 3.1(1) and 3.2(1) {mu}{sub B}, making an angle of 37(1) deg. which is in agreement with the value (39 deg.) provided by the theoretical analysis of the magnetic susceptibility using the model of effective spin 1/2. Polarized neutron diffraction (PND) shows that this dinuclear Co{sup 2+} complex behaves more like a system of two antiferromagnetically coupled ions with spin 3/2, the directions of which are imposed by the distortion axis of the octahedra around each Co{sup 2+} ion due to ligand field. This first application of the local susceptibility tensor method to a molecular compound demonstrates the efficiency of the PND method as a tool for exploring magnetic anisotropy in molecular paramagnets.

  11. [Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

    PubMed

    Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

    2014-10-01

    In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system. PMID:25764715

  12. [Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

    PubMed

    Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

    2014-10-01

    In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

  13. A Unit Cell Laboratory Experiment: Marbles, Magnets, and Stacking Arrangements

    ERIC Educational Resources Information Center

    Collins, David C.

    2011-01-01

    An undergraduate first-semester general chemistry laboratory experiment introducing face-centered, body-centered, and simple cubic unit cells is presented. Emphasis is placed on the stacking arrangement of solid spheres used to produce a particular unit cell. Marbles and spherical magnets are employed to prepare each stacking arrangement. Packing…

  14. [Magnetic resonance--personal experience with its use in otorhinolaryngology].

    PubMed

    Skerík, P; Belán, A; Lízler, J; Dolejs, Z

    1989-07-01

    The authors present their initial experience with the visualization by magnetic resonance (MR) in otorhinolaryngology in the CSR. Due to multidimensional and high contrast visualization, MR facilitates greatly spatial orientation as regards localization and size of the pathological process. Its importance otorhinolaryngology is in particular in the diagnosis of neoplastic diseases. For some localizations of tumours MR is the method of choice. PMID:2791047

  15. A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Hu, Guangyue; Liang, Yihan; Song, Falun; Yuan, Peng; Wang, Yulin; Zhao, Bin; Zheng, Jian

    2015-02-01

    A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast (~230 ns), 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device (ICCD) detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.

  16. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    DOE PAGES

    Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Hahn, Kelly D.; Hansen, Stephanie B.; Knapp, Patrick F.; Schmit, Paul F.; Ruiz, Carlos L.; Sinars, Daniel Brian; Harding, Eric C.; et al

    2015-04-29

    In this study, the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as highmore » as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 1012 have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm3. In these experiments, up to 5 ×1010 secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm2, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 1010. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.« less

  17. Intermittent magnetic field excitations in the Madison Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Nornberg, M. D.; Spence, E. J.; Jacobson, C. M.; Parada, C. A.; Kendrick, R. D.; Forest, C. B.

    2006-10-01

    Determining the onset conditions for magnetic field growth in magnetohydrodynamics is fundamental to understanding how astrophysical dynamos such as the Earth, the Sun, and the galaxy self-generate magnetic fields. The role of turbulence in modifying these onset conditions is studied in the Madison Dynamo Experiment. A turbulent flow of liquid sodium, composed primarily of two counter-rotating helical vortices, is generated by impellers. Laser Doppler velocimetry measurements of the flow in an identical-scale water experiment demonstrate that the turbulence is isotropic, though not homogeneous, with particularly long-lived eddies in the shear layer between the two flow cells. The magnetic field induced when an axial field is applied shows intermittent periods of growth and has a spatial structure consistent with the fastest growing magnetic eigenmode predicted by a laminar kinematic dynamo model of the mean flow. Turbulent fluctuations of the velocity field change the flow geometry such that the eigenmode growth rate is temporarily positive, thus generating the magnetic bursts. It is found from ensemble averaging that the bursts gain strength and frequency with increased impeller rotation rate, though they become shorter so that each burst remains a rare, random event. Nornberg et al., Phys. Rev. Lett., in press (2006), physics/0606239.

  18. X-Ray Diffraction of Intermetallic Compounds: A Physical Chemistry Laboratory Experiment

    ERIC Educational Resources Information Center

    Varberg, Thomas D.; Skakuj, Kacper

    2015-01-01

    Here we describe an experiment for the undergraduate physical chemistry laboratory in which students synthesize the intermetallic compounds AlNi and AlNi3 and study them by X-ray diffractometry. The compounds are synthesized in a simple one-step reaction occurring in the solid state. Powder X-ray diffractograms are recorded for the two compounds…

  19. Aperture-ratio dependence of the efficiency of magneto-optical first-order diffraction in GdFe stripe arrays with alternating perpendicular magnetization

    NASA Astrophysics Data System (ADS)

    Wada, Kakeru; Antos, Roman; Aoshima, Ken-ichi; Machida, Kenji; Kuga, Kiyoshi; Ono, Hiroshi; Kikuchi, Hiroshi; Shimidzu, Naoki; Ishibashi, Takayuki

    2016-07-01

    The efficiency of magneto-optical (MO) diffraction in GdFe stripe arrays with alternating directions of perpendicular magnetization is investigated. The diffraction efficiency depends on the aperture ratio, as theoretically analyzed for an array composed of magnetic and nonmagnetic materials, with the magnetization directions parallel or antiparallel. The stripe patterns are composed of two ferromagnetic alloys of different compositions, Gd19.7Fe80.3 and Gd23.4Fe76.6 (denoted GF1 and GF2), having different coercivities in the parallel and antiparallel configurations. The stripe patterns are separated by nonmagnetic SiO2 stripes of different widths to obtain aperture ratios of 100, 75, 50 and 25%. The magnetization distributions in the samples is confirmed by MO microscopy. The diffraction efficiencies at a wavelength of 532 nm are measured to be 1.27×10-6, 1.04×10-6, 6.2×10-7 and 2.0×10-7 for aperture ratios of 100, 75, 50, and 25%, respectively. Those values are in accord with calculations using the measured MO and optical parameters of the GF1 layer, including the Kerr rotation angle of 0.12°, the Kerr ellipticity of -0.1° and the reflectance of 0.37.

  20. Determination of the easy axes of small ferromagnetic precipitates in a bulk material by combined magnetic force microscopy and electron backscatter diffraction techniques.

    PubMed

    Batista, L; Rabe, U; Hirsekorn, S

    2014-11-01

    A method to determine the magnetic easy axes of micro- and nanoscopic ferromagnetic precipitates embedded in a bulk material is proposed and applied to globular cementite (Fe₃C) embedded in a ferrite matrix. The method combines magnetic force microscopy (MFM) with electron backscattered diffraction (EBSD) measurements. Magnetic domain structures in globular and in lamellar cementite precipitates in unalloyed pearlitic steels were imaged using MFM. The domain structure of the precipitates was analyzed in dependency of their size, shape and crystallographic orientation. It was found that the magnetic moments of the cementite precipitates are highly geared to their crystalline axes. The combined MFM and EBSD studies allow the conclusion that the cementite easy direction of magnetization is the long [010] axis. For fine lamellae cementite the determination of their crystallographic orientations using electron diffraction techniques is very difficult. With the previous knowledge of the behavior of the domain structure in globular cementite, the crystalline orientations of the fine lamellae cementite can be estimated by simply observing the magnetic microstructures and the topographic profiles.

  1. FLASH magnetohydrodynamic simulations of shock-generated magnetic field experiments

    NASA Astrophysics Data System (ADS)

    Tzeferacos, P.; Fatenejad, M.; Flocke, N.; Gregori, G.; Lamb, D. Q.; Lee, D.; Meinecke, J.; Scopatz, A.; Weide, K.

    2012-12-01

    We report the results of benchmark FLASH magnetohydrodynamic (MHD) simulations of experiments conducted by the University of Oxford High Energy Density Laboratory Astrophysics group and its collaborators at the Laboratoire pour l'Utilisation des Lasers Intenses (LULI). In these experiments, a long-pulse laser illuminates a target in a chamber filled with Argon gas, producing shock waves that generate magnetic fields via the Biermann battery mechanism. We first outline the implementation of 2D cylindrical geometry in the unsplit MHD solver in FLASH and present results of verification tests. We then describe the results of benchmark 2D cylindrical MHD simulations of the LULI experiments using FLASH that explore the impact of external fields along with the possibility of magnetic field amplification by turbulence that is associated with the shock waves and that is induced by a grid placed in the gas-filled chamber.

  2. Solenoid Magnet System for the Fermilab Mu2e Experiment

    SciTech Connect

    Lamm, M. J.; Andreev, N.; Ambrosio, G.; Brandt, J.; Coleman, R.; Evbota, D.; Kashikhin, V. V.; Lopes, M.; Miller, J.; Nicol, T.; Ostojic, R.; Page, T.; Peterson, T.; Popp, J.; Pronskikh, V.; Tang, Z.; Tartaglia, M.; Wake, M.; Wands, R.; Yamada, R.

    2011-12-14

    The Fermilab Mu2e experiment seeks to measure the rare process of direct muon to electron conversion in the field of a nucleus. Key to the design of the experiment is a system of three superconducting solenoids; a muon production solenoid (PS) which is a 1.8 m aperture axially graded solenoid with a peak field of 5 T used to focus secondary pions and muons from a production target located in the solenoid aperture; an 'S shaped' transport solenoid (TS) which selects and transports the subsequent muons towards a stopping target; a detector solenoid (DS) which is an axially graded solenoid at the upstream end to focus transported muons to a stopping target, and a spectrometer solenoid at the downstream end to accurately measure the momentum of the outgoing conversion elections. The magnetic field requirements, the significant magnetic coupling between the solenoids, the curved muon transport geometry and the large beam induced energy deposition into the superconducting coils pose significant challenges to the magnetic, mechanical, and thermal design of this system. In this paper a conceptual design for the magnetic system which meets the Mu2e experiment requirements is presented.

  3. Numerical Modeling of a Magnetic Flux Compression Experiment

    NASA Astrophysics Data System (ADS)

    Makhin, Volodymyr; Bauer, Bruno S.; Awe, Thomas J.; Fuelling, Stephan; Goodrich, Tasha; Lindemuth, Irvin R.; Siemon, Richard E.; Garanin, Sergei F.

    2007-06-01

    A possible plasma target for Magnetized Target Fusion (MTF) is a stable diffuse z-pinch in a toroidal cavity, like that in MAGO experiments. To examine key phenomena of such MTF systems, a magnetic flux compression experiment with this geometry is under design. The experiment is modeled with 3 codes: a slug model, the 1D Lagrangian RAVEN code, and the 1D or 2D Eulerian Magneto-Hydro-Radiative-Dynamics-Research (MHRDR) MHD simulation. Even without injection of plasma, high- Z wall plasma is generated by eddy-current Ohmic heating from MG fields. A significant fraction of the available liner kinetic energy goes into Ohmic heating and compression of liner and central-core material. Despite these losses, efficiency of liner compression, expressed as compressed magnetic energy relative to liner kinetic energy, can be close to 50%. With initial fluctuations (1%) imposed on the liner and central conductor density, 2D modeling manifests liner intrusions, caused by the m = 0 Rayleigh-Taylor instability during liner deceleration, and central conductor distortions, caused by the m = 0 curvature-driven MHD instability. At many locations, these modes reduce the gap between the liner and the central core by about a factor of two, to of order 1 mm, at the time of peak magnetic field.

  4. Solenoid Magnet System for the Fermilab Mu2e Experiment

    DOE PAGES

    Lamm, M. J.; Andreev, N.; Ambrosio, G.; Brandt, J.; Coleman, R.; Evbota, D.; Kashikhin, V. V.; Lopes, M.; Miller, J.; Nicol, T.; et al

    2011-12-14

    The Fermilab Mu2e experiment seeks to measure the rare process of direct muon to electron conversion in the field of a nucleus. Key to the design of the experiment is a system of three superconducting solenoids; a muon production solenoid (PS) which is a 1.8 m aperture axially graded solenoid with a peak field of 5 T used to focus secondary pions and muons from a production target located in the solenoid aperture; an 'S shaped' transport solenoid (TS) which selects and transports the subsequent muons towards a stopping target; a detector solenoid (DS) which is an axially graded solenoidmore » at the upstream end to focus transported muons to a stopping target, and a spectrometer solenoid at the downstream end to accurately measure the momentum of the outgoing conversion elections. The magnetic field requirements, the significant magnetic coupling between the solenoids, the curved muon transport geometry and the large beam induced energy deposition into the superconducting coils pose significant challenges to the magnetic, mechanical, and thermal design of this system. In this paper a conceptual design for the magnetic system which meets the Mu2e experiment requirements is presented.« less

  5. Diagnosing magnetized liner inertial fusion experiments on Z

    SciTech Connect

    Hansen, S. B. Gomez, M. R.; Sefkow, A. B.; Slutz, S. A.; Sinars, D. B.; Hahn, K. D.; Harding, E. C.; Knapp, P. F.; Schmit, P. F.; Awe, T. J.; McBride, R. D.; Jennings, C. A.; Geissel, M.; Harvey-Thompson, A. J.; Peterson, K. J.; Rovang, D. C.; Chandler, G. A.; Cooper, G. W.; Cuneo, M. E.; Hess, M. H.; and others

    2015-05-15

    Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (∼10{sup 12} DD neutrons) from multi-keV deuterium plasmas inertially confined by slow (∼10 cm/μs), stable, cylindrical implosions. Effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 10{sup 10}. Analysis of extensive power, imaging, and spectroscopic x-ray measurements provides a detailed picture of ∼3 keV temperatures, 0.3 g/cm{sup 3} densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

  6. Diagnosing magnetized liner inertial fusion experiments on Z

    DOE PAGES

    Hansen, Stephanie B.; Gomez, Matthew R.; Sefkow, Adam B.; Slutz, Stephen A.; Sinars, Daniel Brian; Hahn, Kelly; Harding, Eric; Knapp, Patrick; Schmit, Paul; Awe, Thomas James; et al

    2015-05-14

    The Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (~1012 DD neutrons) from multi-keV deuterium plasmasinertially confined by slow (~10 cm/μs), stable, cylindrical implosions. Moreover, effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 1010. Further analysis of extensive power, imaging, and spectroscopicx-ray measurements provides a detailed picture of ~3 keV temperatures, 0.3 g/cm3 densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

  7. Diagnosing magnetized liner inertial fusion experiments on Z

    SciTech Connect

    Hansen, Stephanie B.; Gomez, Matthew R.; Sefkow, Adam B.; Slutz, Stephen A.; Sinars, Daniel Brian; Hahn, Kelly; Harding, Eric; Knapp, Patrick; Schmit, Paul; Awe, Thomas James; McBride, Ryan D.; Jennings, Christopher; Geissel, Matthias; Harvey-Thompson, Adam James; Peterson, K. J.; Rovang, Dean C.; Chandler, Gordon A.; Cooper, Gary Wayne; Cuneo, Michael Edward; Herrmann, Mark C.; Mark Harry Hess; Johns, Owen; Lamppa, Derek C.; Martin, Matthew; Porter, J. L.; Robertson, G. K.; Rochau, G. A.; Ruiz, C. L.; Savage, M. E.; Smith, I. C.; Stygar, W. A.; Vesey, R. A.; Blue, B. E.; Ryutov, D.; Schroen, Diana; Tomlinson, K.

    2015-05-14

    The Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (~1012 DD neutrons) from multi-keV deuterium plasmasinertially confined by slow (~10 cm/μs), stable, cylindrical implosions. Moreover, effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 1010. Further analysis of extensive power, imaging, and spectroscopicx-ray measurements provides a detailed picture of ~3 keV temperatures, 0.3 g/cm3 densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

  8. Laser-Driven Magnetic-Flux Compression: Theory and Experiments

    NASA Astrophysics Data System (ADS)

    Chang, Po-Yu

    Laser-Driven Flux Compression (LDFC) is a technique used to compress the magnetic field in Inertial Confinement Fusion (ICF) targets driven by a laser. The compressed field in the ICF target is beneficial to the target performance. Embedding a magnetic field in a conventional ICF target reduces the heat loss if the central hot spot becomes magnetized. Higher hot spot temperatures lower the requirements on the implosion velocities, leading to larger shell masses and therefore higher energy gains. For a typical hot spot density of ˜ 10 g/cc, and temperature of ˜ 5 keV, a magnetic field B > 10 MG is required to magnetize the hot spot. Such a strong magnetic field is difficult to be externally generated. Instead of providing the strong magnetic field directly, a seed magnetic field much lower than the required field was provided and compressed by the imploding shell. The field needs to be compressed faster than its diffusion due to the finite resistivity of the fill gas and the shell. This requires the gas in the target being ionized by the shock so that the flux is frozen in the gas region and compressed by the imploding shell. In this thesis, theoretical models, numerical calculations, and basic experiments of flux compression in ICF targets are investigated. A measurable Lawson criterion, developed as a metric to assess the performance of an ICF target, is used to evaluate the benefits of suppressing the heat conductivity. A simple model is used to describe the process of field compression by shock waves during the shell implosion. The magnetohydrodynamics codes, LILAC-MHD and LILAC-MHD-SP, are used to simulate the field compression and the target performance. The Magneto-Inertial-Fusion-Electrical-Discharge-System (MIFEDS), the device providing the seed magnetic field, is described in detail. LDFC experiments using the OMEGA laser at the Laboratory for Laser Energetics are presented. The results include the first demonstration of ˜ 550-fold amplification of a 50

  9. Experiments on Inductive Magnetic Levitation with a Circular Halbach Array

    NASA Astrophysics Data System (ADS)

    Bean, Ian; Goncz, Doug; Raymer, Austin; Specht, Jason; Zalles, Ricardo; Majewski, Walerian

    2013-03-01

    Using a ring Halbach array, we are investigating a repulsive levitating force and a drag force acting on the magnet from a ring of inductors rotating below the magnet. After measuring induced currents, voltages and magnetic fields in the individual inductors (in the form of short solenoids), we investigated the dependence of lift/drag forces on the speed of relative rotation. The ratio of lift to drag increases with the angular velocity, as expected from a related theory of the induction effects in a linear motion. We are experimenting with the shape and density of inductors, and their material, in an attempt to maximize the lift at a minimal velocity of rotation. Eventually this design could have applications as frictionless bearings or as frictionless gear in a wide range of systems, especially in machinery that cannot be easily accessed.

  10. A magnetic gradient induced force in NMR restricted diffusion experiments.

    PubMed

    Ghadirian, Bahman; Stait-Gardner, Tim; Castillo, Reynaldo; Price, William S

    2014-03-28

    We predict that the phase cancellation of a precessing magnetisation field carried by a diffusing species in a bounded geometry under certain nuclear magnetic resonance pulsed magnetic field gradient sequences results in a small force over typically micrometre length scales. Our calculations reveal that the total magnetisation energy in a pore under the influence of a pulsed gradient will be distance-dependent thus resulting in a force acting on the boundary. It is shown that this effect of the magnetisation of diffusing particles will appear as either an attractive or repulsive force depending on the geometry of the pore and magnetic properties of the material. A detailed analysis is performed for the case of a pulsed gradient spin-echo experiment on parallel planes. It is shown that the force decays exponentially in terms of the spin-spin relaxation. The proof is based on classical electrodynamics. An application of this effect to soft matter is suggested.

  11. Preliminary experiments on SAW based magnetization switching of nanomagnets

    NASA Astrophysics Data System (ADS)

    Sampath, Vimal; D'Souza, Noel; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha

    2015-03-01

    Magnetization rotation in micron-sized ferromagnetic elements, using Surface Acoustic Waves (SAW), has been demonstrated experimentally while the use of SAW to lower the energy dissipation in switching of nanomagnets with spin transfer torque has been studied theoretically. Furthermore, SAW can be used to ``Bennett clock'' an array of nanomagnets in nanomagnetic logic without requiring lithographic contacts to individual nanomagnets. We report preliminary experiments on use of SAW to switch magnetostrictive Co nanomagnets grown on bulk 128 Y-cut lithium niobate. Switching is studied by imaging the nanomagnets' magnetic states with Magnetic Force Microscopy (MFM) before and after the SAW waves interact with them. Switching of single, isolated nanomagnets of various sizes, and dipole coupled nanomagnets implementing a Boolean NOT gate, is studied. This work is supported by the US National Science Foundation under the SHF-Small Grant CCF-1216614, CAREER Grant CCF-1253370, NEB 2020 Grant ECCS-1124714 and SRC under NRI Task 2203.001.

  12. A magnetic gradient induced force in NMR restricted diffusion experiments

    SciTech Connect

    Ghadirian, Bahman; Stait-Gardner, Tim; Castillo, Reynaldo; Price, William S.

    2014-03-28

    We predict that the phase cancellation of a precessing magnetisation field carried by a diffusing species in a bounded geometry under certain nuclear magnetic resonance pulsed magnetic field gradient sequences results in a small force over typically micrometre length scales. Our calculations reveal that the total magnetisation energy in a pore under the influence of a pulsed gradient will be distance-dependent thus resulting in a force acting on the boundary. It is shown that this effect of the magnetisation of diffusing particles will appear as either an attractive or repulsive force depending on the geometry of the pore and magnetic properties of the material. A detailed analysis is performed for the case of a pulsed gradient spin-echo experiment on parallel planes. It is shown that the force decays exponentially in terms of the spin-spin relaxation. The proof is based on classical electrodynamics. An application of this effect to soft matter is suggested.

  13. Magnetic diagnostics on the Lockheed Martin T4 Experiment

    NASA Astrophysics Data System (ADS)

    Rhoads, John

    2015-11-01

    The Lockheed Martin T4 Experiment is a magnetically encapsulated linear ring cusp confinement device designed to study the physics relevant to the Compact Fusion Reactor program. As part of the diagnostics suite, an invasive three-axis magnetic probe and several flux loops have been constructed and installed. The probe was designed to reduce electrostatic pick-up by differentially amplifying two counter-wound coils for each axis. The flux loops are designed to detect plasma diamagnetism after accounting for the flux due to the background magnetic field. This mandates that the temporal evolution of the background field must be properly taken into account in order to discern the plasma response. To this end, both hardware and software techniques have been employed. Diagnostic designs and preliminary measurements will be presented.

  14. PIC Simulations of the Omega-EP Magnetic Reconnection Experiment

    NASA Astrophysics Data System (ADS)

    Liu, Wenda; Blackman, Eric; Yan, Rui; Ren, Chuang

    2014-10-01

    In an Omega EP experiment on magnetic reconnection, two laser beams with peak intensity of 7 × 1018 W/cm2 are focused on a Cu-target. Here we report 2D PIC simulation results with parameters derived from the experiment including a realistic ion-electron mass ratio. We find that 1) toroidal and mega-gauss-scale magnetic fields are generated and a bubble of high-energy-density plasma is produced from single beam-target interactions and 2) the magnetic topology changes as two such bubbles expand and interact with each other indicating the occurrence of magnetic reconnection. The reconnection can occur even when the bubble expansion velocity is subsonic. Flux pileup is observed when the expansion velocity is supersonic. Energetic Cu-ions with energy up to 12 MeV are also observed in the outflow. This work was supported by NNSA under Corporate Agreement No. DE-FC52-08NA28302 and Grant No. DE-NA0002205; by DOE under Grant No. DE-FC02-04ER54789; and by NSF under Grant No. PHY-1314734.

  15. Design and Assembly of the Magnetized Dusty Plasma Experiment (MDPX)

    NASA Astrophysics Data System (ADS)

    Fisher, Ross; Artis, Darrick; Lynch, Brian; Wood, Keith; Shaw, Joseph; Gilmore, Kevin; Robinson, Daniel; Polka, Christian; Konopka, Uwe; Thomas, Edward; Merlino, Robert; Rosenberg, Marlene

    2013-10-01

    Over the last two years, the Magnetized Dusty Plasma Experiment (MDPX) has been under construction at Auburn University. This new research device, whose assembly will be completed in late Summer, 2013, uses a four-coil, superconducting, high magnetic field system (|B | >= 4 Tesla) to investigate the confinement, charging, transport, and instabilities in a dusty plasma. A new feature of the MDPX device is the ability to operate the magnetic coils independently to allow a variety of magnetic configurations from highly uniform to quadrapole-like. Envisioned as a multi-user facility, the MDPX device features a cylindrical vacuum vessel whose primary experimental region is an octagonal chamber that has a 35.5 cm inner diameter and is 19 cm tall. There is substantial diagnostics and optical access through eight, 10.2 cm × 12.7 cm side ports. The chamber can also be equipped with two 15.2 cm diameter, 76 cm long extensions to allow long plasma column experiments, particularly long wavelength dust wave studies. This presentation will discuss the final design, assembly, and installation of the MDPX device and will describe its supporting laboratory facility. This work is supported by a National Science Foundation - Major Research Instrumentation (NSF-MRI) award, PHY-1126067.

  16. Experiments of cylindrical isentropic compression by ultrahigh magnetic field

    NASA Astrophysics Data System (ADS)

    Gu, Zhuowei; Zhou, Zhongyu; Zhang, Chunbo; Tang, Xiaosong; Tong, Yanjin; Zhao, Jianheng; Sun, Chengwei

    2015-09-01

    The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5-6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.

  17. History and Solution of the Phase Problem in the Theory of Structure Determination of Crystals from X-ray Diffraction Experiments

    SciTech Connect

    Wolf, Emil

    2010-06-02

    Since the pioneering work of Max von Laue on interference and diffraction of x-rays, carried out almost 100 years ago, numerous attempts have been made to determine structures of crystalline media from x-ray diffraction experiments. The usefulness of all of them has been limited by the inability of measuring phases of the diffracted beams. In this talk, the most important research carried out in this field will be reviewed and a recently obtained solution of the phase problem will be presented.

  18. History and Solution of the Phase Problem in theTheory of Structure Determination of Crystals from X-ray Diffraction Experiments

    ScienceCinema

    Wolf, Emil [University of Rochester, Rochester, New York, United States

    2016-07-12

    Since the pioneering work of Max von Laue on interference and diffraction of x-rays, carried out almost 100 years ago, numerous attempts have been made to determine structures of crystalline media from x-ray diffraction experiments. The usefulness of all of them has been limited by the inability of measuring phases of the diffracted beams. In this talk, the most important research carried out in this field will be reviewed and a recently obtained solution of the phase problem will be presented.

  19. Gravitropic mechanisms derived from space experiments and magnetic gradients.

    NASA Astrophysics Data System (ADS)

    Hasenstein, Karl H.; Park, Myoung Ryoul

    2016-07-01

    Gravitropism is the result of a complex sequence of events that begins with the movement of dense particles, typically starch-filled amyloplasts in response to reorientation. Although these organelles change positions, it is not clear whether the critical signal is derived from sedimentation or dynamic interactions of amyloplasts with relevant membranes. Substituting gravity by high-gradient magnetic fields (HGMF) provides a localized stimulus for diamagnetic starch that is specific for amyloplasts and comparable to gravity without affecting other organelles. Experiments with Brassica rapa showed induction of root curvature by HGMF when roots moved sufficiently close to the magnetic gradient-inducing foci. The focused and short-range effectiveness of HGMFs provided a gravity-like stimulus and affected related gene expression. Root curvature was sensitive to the mutual alignment between roots and HGMF direction. Unrelated to any HGMF effects, the size of amyloplasts in space-grown roots increased by 30% compared to ground controls and suggests enhanced sensitivity in a gravity-reduced environment. Accompanying gene transcription studies showed greater differences between HGMF-exposed and space controls than between space and ground controls. This observation may lead to the identification of gravitropism-relevant genes. However, space grown roots showed stronger transcription of common reference genes such as actin and ubiquitin in magnetic fields than in non-magnetic conditions. In contrast, α-amylase, glucokinase and PIN encoding genes were transcribed stronger under non-magnetic conditions than under HGMF. The large number of comparisons between space, ground, and HGMF prompted the assessment of transcription differences between root segments, root-shoot junction, and seeds. Because presumed transcription of reference genes varied more than genes of interest, changes in gene expression cannot be based on reference genes. The data provide an example of complex

  20. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    SciTech Connect

    Gomez, Matthew R.; Slutz, Stephen A.; Sefkow, Adam B.; Hahn, Kelly D.; Hansen, Stephanie B.; Knapp, Patrick F.; Schmit, Paul F.; Ruiz, Carlos L.; Sinars, Daniel Brian; Harding, Eric C.; Jennings, Christopher A.; Awe, Thomas James; Geissel, Matthias; Rovang, Dean C.; Smith, Ian C.; Chandler, Gordon A.; Cooper, Gary Wayne; Cuneo, Michael Edward; Harvey-Thompson, Adam James; Herrmann, Mark C.; Mark Harry Hess; Lamppa, Derek C.; Martin, Matthew R.; McBride, Ryan D.; Peterson, Kyle J.; Porter, John L.; Rochau, Gregory A.; Savage, Mark E.; Schroen, Diana G.; Stygar, William A.; Vesey, Roger Alan

    2015-04-29

    In this study, the magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as high as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 1012 have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm3. In these experiments, up to 5 ×1010 secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm2, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 1010. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.

  1. Demonstration of thermonuclear conditions in magnetized liner inertial fusion experiments

    SciTech Connect

    Gomez, M. R.; Slutz, S. A.; Sefkow, A. B.; Hahn, K. D.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Ruiz, C. L.; Sinars, D. B.; Harding, E. C.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Smith, I. C.; Chandler, G. A.; Cooper, G. W.; Cuneo, M. E.; Harvey-Thompson, A. J.; Hess, M. H.; and others

    2015-05-15

    The magnetized liner inertial fusion concept [S. A. Slutz et al., Phys. Plasmas 17, 056303 (2010)] utilizes a magnetic field and laser heating to relax the pressure requirements of inertial confinement fusion. The first experiments to test the concept [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] were conducted utilizing the 19 MA, 100 ns Z machine, the 2.5 kJ, 1 TW Z Beamlet laser, and the 10 T Applied B-field on Z system. Despite an estimated implosion velocity of only 70 km/s in these experiments, electron and ion temperatures at stagnation were as high as 3 keV, and thermonuclear deuterium-deuterium neutron yields up to 2 × 10{sup 12} have been produced. X-ray emission from the fuel at stagnation had widths ranging from 50 to 110 μm over a roughly 80% of the axial extent of the target (6–8 mm) and lasted approximately 2 ns. X-ray yields from these experiments are consistent with a stagnation density of the hot fuel equal to 0.2–0.4 g/cm{sup 3}. In these experiments, up to 5 × 10{sup 10} secondary deuterium-tritium neutrons were produced. Given that the areal density of the plasma was approximately 1–2 mg/cm{sup 2}, this indicates the stagnation plasma was significantly magnetized, which is consistent with the anisotropy observed in the deuterium-tritium neutron spectra. Control experiments where the laser and/or magnetic field were not utilized failed to produce stagnation temperatures greater than 1 keV and primary deuterium-deuterium yields greater than 10{sup 10}. An additional control experiment where the fuel contained a sufficient dopant fraction to substantially increase radiative losses also failed to produce a relevant stagnation temperature. The results of these experiments are consistent with a thermonuclear neutron source.

  2. A novel approach for x-ray scattering experiments in magnetic fields utilizing trapped flux in type-II superconductors

    SciTech Connect

    Das, R.K.; Islan, Z.; Ruff, J.P.C.; Sawh, R.P.; Weinstein, R.; Canfield, Paul C.; Kim, J.-W.; Lang, J.C.

    2012-06-08

    We introduce a novel approach to x-ray scattering studies in applied magnetic fields by exploiting vortices in superconductors. This method is based on trapping magnetic flux in a small disk-shaped superconductor (known as a trapped field magnet, TFM) with a single-crystal sample mounted on or at close proximity to its surface. This opens an unrestricted optical access to the sample and allows magnetic fields to be applied precisely along the x-ray momentum transfer, facilitating polarization-sensitive experiments that have been impractical or impossible to perform to date. The TFMs used in our study remain stable and provide practically uniform magnetic fields for days, which are sufficient for comprehensive x-ray diffraction experiments, specifically x-ray resonance exchange scattering (XRES) to study field-induced phenomena at a modern synchrotron source. The TFM instrument has been used in a “proof-of-principle” XRES study of a meta-magnetic phase in a rare-earth compound, TbNi2Ge2, in order to demonstrate its potential.

  3. Magnetic Systems in Megagauss Magnetic Fields:. Results of Dirac and Kapitsa Experiments

    NASA Astrophysics Data System (ADS)

    Tatsenko, O. M.; Selemir, V. D.

    2004-11-01

    The paper discusses the experimental series of Dirac-II and Kapitsa to explore material properties in ultra-high magnetic fields. A set of Dirac experiments was performed in June 1996 at Los Alamos National Laboratory. Scientists from six countries and eight Universities tested more than 60 samples in five explosive experiments using magnetocumulative generators of ultra-high magnetic fields. Test measurements were made using a 50 Tesla magnet of the NHMFL user facility ot LANL. The first scientific and practical workshop, Kapitsa, was performed in 1997 at the Russian Nuclear Federal Center (Sarov). More than 15 samples were tested during three shots. The Kapitsa series is planned to be performed annually. In the Kapitsa and Dirac experiments we explored magnetization of high-spin clusters Mn12Ac, Mn6, Fe8, fulleren C60, metamagnetic transitions in ScCo2, valence transitions in EuNi2(Si1-xGex)2 and the transition semiconductor-metal in FeSi.

  4. Magnetic shielding of a laboratory Hall thruster. II. Experiments

    SciTech Connect

    Hofer, Richard R. Goebel, Dan M.; Mikellides, Ioannis G.; Katz, Ira

    2014-01-28

    The physics of magnetic shielding in Hall thrusters were validated through laboratory experiments demonstrating essentially erosionless, high-performance operation. The magnetic field near the walls of a laboratory Hall thruster was modified to effectively eliminate wall erosion while maintaining the magnetic field topology away from the walls necessary to retain efficient operation. Plasma measurements at the walls validate our understanding of magnetic shielding as derived from the theory. The plasma potential was maintained very near the anode potential, the electron temperature was reduced by a factor of two to three, and the ion current density was reduced by at least a factor of two. Measurements of the carbon backsputter rate, wall geometry, and direct measurement of plasma properties at the wall indicate that the wall erosion rate was reduced by a factor of 1000 relative to the unshielded thruster. These changes effectively eliminate wall erosion as a life limitation in Hall thrusters, enabling a new class of deep-space missions that could not previously be attempted.

  5. US/Russian Magnetized Target Fusion Plasma Formation Experiments

    NASA Astrophysics Data System (ADS)

    Benage, John F., Jr.; Mtf Team; Broste, W.; Westley, D.; Mago Team

    1998-11-01

    Magnetized target fusion (MTF) is a potentially very low cost route to producing a fusion energy source. Many of MTF's plasma properties are intermediate between magnetically confined fusion (MFE) and inertially confined fusion (ICF). MTF consists of first producing a magnetically thermally insulated target plasma with a temperature of 100 eV or more with a lifetime of 5-10 microseconds. The target plasma is then compressed to fusion conditions by a magnetically driven imploding liner. One target plasma candidate is VNIIEF's MAGO, in which a cylindrical chamber with two cavities is filled with DT gas at a pressure of 10 Torr and driven by a current of 2-8 MA. A series of experiments under different plasma conditions have been performed to evaluate MAGO as an MTF target plasma. Diagnostics used to characterize the MAGO plasma include B dot probes to measure the current distribution, filtered silicon diodes to measure the spectrum and duration of the plasma radiation and a UV spectrometer to measure impurity line radiation.

  6. Diagnostic Progress and Results on the Magnetized Shock Experiment

    NASA Astrophysics Data System (ADS)

    Smith, R. J.; Weber, T. E.

    2015-11-01

    The Magnetized Shock Experiment (MSX) at LANL is reliably producing Field Reversed Configuration (FRC) plasmas spanning peak densities of ~ 1021-23 m-3, combined Te +Ti of 10s-500eV and velocities of 100-300km/s as a means to producing a laboratory supercritical collision-less shock. Visible light images showing discontinuities indicative of shocks and jetting have been obtained on various targets: co-solenoid B field, a metal wall and counter-solenoidal B fields (FRC capture and reconnection). Two chord interferometry, external and internal magnetic probing are routinely employed and x-ray diagnostic capability has recently been added. The pulsed polarimetry technique is being deployed which can measure the local magnetic field using Lidar Thomson scattering. In addition, a fiber optic version of pulsed polarimetry using a new specialty fiber that enhances fiber backscatter with Fiber Bragg Gratings is being developed. Magnetic fields of order ~ 1T have been measured, however a new modified shock chamber geometry and recent machine modifications enabling operation at increased θ-coil voltage are expected to improve translation speed and hence stagnation pressures. Progress on these diagnostics and results will be presented. DOE support Grant No DE-SC00010559.

  7. Neutron powder diffraction study and magnetic properties in LaMn1-xCuxO3 (x=0.05, 0.10 and 0.15)

    NASA Astrophysics Data System (ADS)

    Samantaray, B.; Srivastava, S. K.; Mohanty, S.; Ravi, S.; Dhiman, I.; Das, A.

    2010-05-01

    LaMn1-xCuxO3 (x=0.05 to 0.15) samples were prepared and their crystal structure and magnetic properties were studied by recording neutron powder diffraction patterns and M-H loops at different temperatures. Even though the samples were free from impurity, the x=0.05 and 0.10 samples are found to crystallize in mixture of R3¯c and Pnma space group with dominate fraction of former one. The phase fraction for x=0.10 sample is found to vary with temperature especially below the ferromagnetic TC. The x=0.15 sample could be refined based on Pnma space group. The patterns at low temperatures could be refined by considering magnetic reflections corresponding to ferromagnetic structure. The magnetic moments of Mn ion are found to be along b axis with typical value of 3.40(3)μB for x=0.10 sample. From the analysis of the diffraction patterns and the magnetization data, it is found that x=0.15 sample exhibit spin canting.

  8. First spin-resolved electron distributions in crystals from combined polarized neutron and X-ray diffraction experiments

    PubMed Central

    Deutsch, Maxime; Gillon, Béatrice; Claiser, Nicolas; Gillet, Jean-Michel; Lecomte, Claude; Souhassou, Mohamed

    2014-01-01

    Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density) and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT) calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed. PMID:25075338

  9. Magnetic field experiment for Voyagers 1 and 2

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.; Aluna, M. H.; Burlaga, L. F.; Lepping, R. P.; Ness, N. F.; Neubauer, F. M.

    1977-01-01

    The magnetic field experiment to be carried on the Voyager 1 and 2 missions consists of dual low field (LFM) and high field magnetometer (HFM) systems. The dual systems provide greater reliability and, in the case of the LFM's, permit the separation of spacecraft magnetic fields from the ambient fields. Additional reliability is achieved through electronics redundancy. The wide dynamic ranges of plus or minus 0.5G for the LFM's and plus or minus 20G for the HFM's, low quantization uncertainty of plus or minus 0.002 gamma in the most sensitive (plus or minus 8 gamma) LFM range, low sensor RMS noise level of 0.006 gamma, and use of data compaction schemes to optimize the experiment information rate all combine to permit the study of a broad spectrum of phenomena during the mission. Planetary fields at Jupiter, Saturn, and possibly Uranus; satellites of these planets; solar wind and satellite interactions with the planetary fields; and the large-scale structure and microscale characteristics of the interplanetary magnetic field are studied. The interstellar field may also be measured.

  10. Overview and recent results of the Magnetized Shock Experiment (MSX)

    NASA Astrophysics Data System (ADS)

    Weber, T. E.; Smith, R. J.; Hsu, S. C.; Omelchenko, Y.

    2015-11-01

    Recent machine and diagnostics upgrades to the Magnetized Shock Experiment (MSX) at LANL have enabled unprecedented access to the physical processes arising from stagnating magnetized (β ~ 1), collisionless, highly supersonic (M ,MA ~ 10) flows, similar in dimensionless parameters to those found in both space and astrophysical shocks. Hot (100s of eV during translation), dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids are accelerated to high velocities (100s of km/s) and subsequently impact against a static target such as a strong parallel or anti-parallel (reconnection-wise) magnetic mirror, a solid obstacle, or neutral gas cloud to recreate the physics of interest with characteristic length and time scales that are both large enough to observe yet small enough to fit within the experiment. Long-lived (>50 μs) stagnated plasmas with density enhancement much greater than predicted by fluid theory (>4x) are observed, accompanied by discontinuous plasma structures indicating shocks and jetting (visible emission and interferometry) and copious >1 keV x-ray emission. An overview of the experimental program will be presented, including machine design and capabilities, diagnostics, and an examination of the physical processes that occur during stagnation against a variety of targets. Supported by the DOE Office of Fusion Energy Sciences under contract DE-AC52-06NA25369.

  11. Microstructures in CoPtC magnetic thin films studied by superpositioning of micro-electron diffraction

    PubMed

    Tomita; Sugiyama; Sato; Delaunay; Hayashi

    2000-01-01

    Cross-sectional transmission electron microscopy observation of CoPtC thin films showed that 10 nm sized ultrafine particles of CoPt typically were elongated along the substrate normal. Analysis of the superposition of 40 micro-electron diffraction patterns showed that there was no preferred crystal orientation of CoPt particles. This superpositioning technique can be applied to thin films, whose X-ray diffraction analysis is difficult due to the small size of the crystals. PMID:10791426

  12. Influence on cell death of high frequency motion of magnetic nanoparticles during magnetic hyperthermia experiments

    NASA Astrophysics Data System (ADS)

    Hallali, N.; Clerc, P.; Fourmy, D.; Gigoux, V.; Carrey, J.

    2016-07-01

    Studies with transplanted tumors in animals and clinical trials have provided the proof-of-concept of magnetic hyperthermia (MH) therapy of cancers using iron oxide nanoparticles. Interestingly, in several studies, the application of an alternating magnetic field (AMF) to tumor cells having internalized and accumulated magnetic nanoparticles (MNPs) into their lysosomes can induce cell death without detectable temperature increase. To explain these results, among other hypotheses, it was proposed that cell death could be due to the high-frequency translational motion of MNPs under the influence of the AMF gradient generated involuntarily by most inductors. Such mechanical actions of MNPs might cause cellular damages and participate in the induction of cell death under MH conditions. To test this hypothesis, we developed a setup maximizing this effect. It is composed of an anti-Helmholtz coil and two permanent magnets, which produce an AMF gradient and a superimposed static MF. We have measured the MNP heating power and treated tumor cells by a standard AMF and by an AMF gradient, on which was added or not a static magnetic field. We showed that the presence of a static magnetic field prevents MNP heating and cell death in standard MH conditions. The heating power of MNPs in an AMF gradient is weak, position-dependent, and related to the presence of a non-zero AMF. Under an AMF gradient and a static field, no MNP heating and cell death were measured. Consequently, the hypothesis that translational motions could be involved in cell death during MH experiments is ruled out by our experiments.

  13. High power heating of magnetic reconnection in merging tokamak experiments

    SciTech Connect

    Ono, Y.; Tanabe, H.; Gi, K.; Watanabe, T.; Ii, T.; Yamada, T.; Gryaznevich, M.; Scannell, R.; Conway, N.; Crowley, B.; Michael, C.

    2015-05-15

    Significant ion/electron heating of magnetic reconnection up to 1.2 keV was documented in two spherical tokamak plasma merging experiment on MAST with the significantly large Reynolds number R∼10{sup 5}. Measured 1D/2D contours of ion and electron temperatures reveal clearly energy-conversion mechanisms of magnetic reconnection: huge outflow heating of ions in the downstream and localized heating of electrons at the X-point. Ions are accelerated up to the order of poloidal Alfven speed in the reconnection outflow region and are thermalized by fast shock-like density pileups formed in the downstreams, in agreement with recent solar satellite observations and PIC simulation results. The magnetic reconnection efficiently converts the reconnecting (poloidal) magnetic energy mostly into ion thermal energy through the outflow, causing the reconnection heating energy proportional to square of the reconnecting (poloidal) magnetic field B{sub rec}{sup 2}  ∼  B{sub p}{sup 2}. The guide toroidal field B{sub t} does not affect the bulk heating of ions and electrons, probably because the reconnection/outflow speeds are determined mostly by the external driven inflow by the help of another fast reconnection mechanism: intermittent sheet ejection. The localized electron heating at the X-point increases sharply with the guide toroidal field B{sub t}, probably because the toroidal field increases electron confinement and acceleration length along the X-line. 2D measurements of magnetic field and temperatures in the TS-3 tokamak merging experiment also reveal the detailed reconnection heating mechanisms mentioned above. The high-power heating of tokamak merging is useful not only for laboratory study of reconnection but also for economical startup and heating of tokamak plasmas. The MAST/TS-3 tokamak merging with B{sub p} > 0.4 T will enables us to heat the plasma to the alpha heating regime: T{sub i} > 5 keV without using any additional heating facility.

  14. Non-destructive magneto-strain analysis of YB2Cu3Oy superconducting magnets using neutron diffraction in the time-of-flight mode

    NASA Astrophysics Data System (ADS)

    Tomita, M.; Muralidhar, M.; Suzuki, K.; Ishihara, A.; Fukumoto, Y.; Osamura, K.; Machiya, S.; Harjo, S.

    2012-09-01

    In general, neutron diffraction allows a non-destructive investigation of bulk samples. In this study, a magneto-strain analysis of the trapped field in YB2Cu3Oy "YBCO" superconducting bulks was carried out at 45 K using neutron diffraction time-of-flight (TOF) method. The TAKUMI TOF neutron diffractometer offers unique advantages, including accommodation of large objectives, control of the experimental set-up using a 4-axial goniometer (XYZθ), and a positional resolution of 0.01 mm allowing an accurate sample positioning. As a result, the lattice strain in the YB2Cu3Oy material could be estimated in both radial and hoop directions by estimating the difference of plane spacing with/without the trapped magnetic field. The results indicate that the samples with a low trapped field values have smaller magnetic strain than those with a high trapped field. Further, the strain in the hoop direction is higher than that in the radial direction. The present results indicate that neutron diffraction measurements are an effective method for evaluating the bulk residual strains in a non-destructive manner.

  15. "Smart" Magnetic Fluids Experiment Operated on the International Space Station

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.; Lekan, Jack F.

    2004-01-01

    InSPACE is a microgravity fluid physics experiment that was operated on the International Space Station (ISS) in the Microgravity Science Glovebox from late March 2003 through early July 2003. (InSPACE is an acronym for Investigating the Structure of Paramagnetic Aggregates From Colloidal Emulsions.) The purpose of the experiment is to obtain fundamental data of the complex properties of an exciting class of smart materials termed magnetorheological (MR) fluids. MR fluids are suspensions, or colloids, comprised of small (micrometer-sized) superparamagnetic particles in a nonmagnetic medium. Colloids are suspensions of very small particles suspended in a liquid. (Examples of other colloids are blood, milk, and paint.) These controllable fluids can quickly transition into a nearly solid state when exposed to a magnetic field and return to their original liquid state when the magnetic field is removed. Controlling the strength of the magnetic field can control the relative stiffness of these fluids. MR fluids can be used to improve or develop new seat suspensions, robotics, clutches, airplane landing gear, and vibration damping systems. The principal investigator for InSPACE is Professor Alice P. Gast of the Massachusetts Institute of Technology (MIT). The InSPACE hardware was developed at the NASA Glenn Research Center. The InSPACE samples were delivered to the ISS in November 2002, on the Space Shuttle Endeavour, on Space Station Utilization Flight UF-2/STS113. Operations began on March 31, 2003, with the processing of three different particle size samples at multiple test parameters. This investigation focused on determining the structural organization of MR colloidal aggregates when exposed to a pulsing magnetic field. On Earth, the aggregates take the shape of footballs with spiky tips. This characteristic shape may be influenced by the pull of gravity, which causes most particles initially suspended in the fluid to sediment, (i.e., settle and collect at the

  16. Electromagnetic diffraction by plane reflection diffraction gratings

    NASA Technical Reports Server (NTRS)

    Bocker, R. P.; Marathay, A. S.

    1972-01-01

    A plane wave theory was developed to study electromagnetic diffraction by plane reflection diffraction gratings of infinite extent. A computer program was written to calculate the energy distribution in the various orders of diffraction for the cases when the electric or magnetic field vectors are parallel to the grating grooves. Within the region of validity of this theory, results were in excellent agreement with those in the literature. Energy conservation checks were also made to determine the region of validity of the plane wave theory. The computer program was flexible enough to analyze any grating profile that could be described by a single value function f(x). Within the region of validity the program could be used with confidence. The computer program was used to investigate the polarization and blaze properties of the diffraction grating.

  17. X-ray diffraction experiments on the Materials in Extreme Conditions (MEC) LCLS x-ray FEL beamline

    NASA Astrophysics Data System (ADS)

    Smith, Raymond; Fratanduono, Dayne; Wicks, June; Duffy, Tom; Lee, Hae Ja; Granados, Eduardo; Heimann, Philip; Gleason, Arianna; Bolme, Cynthia; Swift, Damian; Coppari, Federica; Eggert, Jon; Collins, Rip

    2015-06-01

    The experiments described here were conducted on the MEC beamline hutch at the SLAC Linac Coherent Light Source. A 10 ns 527 nm laser pulse was used to shock compress 60-100 μm thick NaCl and Graphite samples. LCLS x-rays (40 fs, 8 keV), scattered off the shocked sample, were recorded on several pixel array detectors positioned downstream. The diffracted x-ray pattern allows us to determine changes in crystal structure at Mbar pressures and over nanosecond timescales. In this talk we detail the experimental setup, the current capabilities of the MEC laser and the considerations for optimizing the target design. We will describe the wave interactions within the shock-compressed target and the use of a 1D hydrocode to describe the pressure, temperature and density conditions within the target assembly as a function of time and Lagrangian position. We present observations of the B1-B2 phase transition in NaCl and subsequent back transformation during release to ambient pressure, and compare these findings to gas gun and static data. We also present results from a preliminary study of the shock-induced graphite to diamond transformation.

  18. Humidity control and hydrophilic glue coating applied to mounted protein crystals improves X-ray diffraction experiments

    SciTech Connect

    Baba, Seiki; Hoshino, Takeshi; Ito, Len; Kumasaka, Takashi

    2013-09-01

    A new crystal-mounting method has been developed that involves a combination of controlled humid air and polymer glue for crystal coating. This method is particularly useful when applied to fragile protein crystals that are known to be sensitive to subtle changes in their physicochemical environment. Protein crystals are fragile, and it is sometimes difficult to find conditions suitable for handling and cryocooling the crystals before conducting X-ray diffraction experiments. To overcome this issue, a protein crystal-mounting method has been developed that involves a water-soluble polymer and controlled humid air that can adjust the moisture content of a mounted crystal. By coating crystals with polymer glue and exposing them to controlled humid air, the crystals were stable at room temperature and were cryocooled under optimized humidity. Moreover, the glue-coated crystals reproducibly showed gradual transformations of their lattice constants in response to a change in humidity; thus, using this method, a series of isomorphous crystals can be prepared. This technique is valuable when working on fragile protein crystals, including membrane proteins, and will also be useful for multi-crystal data collection.

  19. Magnetized Plasma Experiments Using Thermionic- Thermoelectronic Plasma Emitter

    NASA Astrophysics Data System (ADS)

    Kawamori, Eiichirou; Cheng, C. Z.; Fujikawa, Nobuko; Lee, Jyun-Yi; Peng, Albert

    2008-11-01

    We are developing a magnetic mirror device, which is the first magnetized plasma device in Taiwan, to explore basic plasma sciences relevant to fusion, space and astrophysical plasmas. Our research subjects include electromagnetically induced transparency (EIT), Alfven wave physics, and plasma turbulence. A large diameter (> 200 mm) plasma emitter1, which utilizes thermionic- thermoelectronic emission from a mixture of LaB6 (Lanthanum-hexaboride) and beta-eucryptite (lithium type aluminosylicate) powders, is employed as a plasma source because of its production ability of fully ionized plasma and controllability of plasma emission rate. The plasma emitter has been installed recently and investigation of its characteristics will be started. The employment of beta-eucryptite in plasma emitter is the first experimental test because such investigation of beta-eucryptite has previously been used only for Li+-ion source2. Our plan for magnetized plasma experiments and results of the plasma emitter investigation will be presented. 1. K. Saeki, S. Iizuka, N. Sato, and Y. Hatta, Appl. Phys. Lett., 37, 1980, pp. 37-38. 2. M. Ueda, R. R. Silva, R. M. Oliveira, H. Iguchi, J. Fujita and K. Kadota, J. Phys. D: Appl. Phys. 30 1997, pp. 2711--2716.

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

    SciTech Connect

    Hutsel, Brian Thomas; Stoltzfus, Brian S.; Fowler, William E.; LeChien, Keith R.; Mazarakis, Michael G.; Moore, James K.; Mulville, Thomas D.; Savage, Mark E.; Stygar, William A.; McKenney, John L.; Jones, Peter A.; MacRunnels, Diego J.; Long, Finis W.; Porter, John L.

    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. Structural and magnetic phase transitions in the synthetic clinopyroxene LiCrGe2O6: a neutron diffraction study between 0.5 and 1473 K

    NASA Astrophysics Data System (ADS)

    Redhammer, Günther J.; Senyshyn, Anatoliy; Tippelt, Gerold; Prinz, Sebastian; Roth, Georg

    2015-06-01

    The pyroxene-type compound LiCrGe2O6, the Li- and Ge-analogue to the silicate mineral kosmochlor, has been synthesized at 1373 K and investigated by neutron diffraction between 0.5 and 1473 K in order to investigate the variation in magnetic and crystal structure with temperature. A structural phase transition from a low-temperature P21/ c to a high-temperature C2/ c structure was found around 1140 K. The two different structures exhibit different thermal expansion behavior with temperature with a reversal of the largest thermal expansion from the c-axis to the b-axis in the P21/ c and C2/ c phase, respectively. The structural phase transition is accompanied by a large volume increase of 1.9 % and sharp discontinuities in bond lengths, especially for the Li-O and—to a lesser extent—for the Cr-O bonds. At low temperature, some additional nonlinear changes in lattice parameters occur, which are associated with a magnetoelastic couplings of the lattice. Magnetic ordering is observed below 6 K in the neutron diffraction data. Data could be indexed with k = (0 0 0), giving rise to magnetic space group P21'/ c. This model of the magnetic structure has a pure antiferromagnetic arrangement of spins, both within and between the M1 chains. The spins are oriented within the a- c plane with an almost nil component along [0 1 0]. A shift of the Cr atom out of the center in the equatorial plane of the octahedron is observed below 6 K and is associated with the magnetic phase transition.

  2. Determination of the hyperfine magnetic field in magnetic carbon-based materials: DFT calculations and NMR experiments

    PubMed Central

    Freitas, Jair C. C.; Scopel, Wanderlã L.; Paz, Wendel S.; Bernardes, Leandro V.; Cunha-Filho, Francisco E.; Speglich, Carlos; Araújo-Moreira, Fernando M.; Pelc, Damjan; Cvitanić, Tonči; Požek, Miroslav

    2015-01-01

    The prospect of carbon-based magnetic materials is of immense fundamental and practical importance, and information on atomic-scale features is required for a better understanding of the mechanisms leading to carbon magnetism. Here we report the first direct detection of the microscopic magnetic field produced at 13C nuclei in a ferromagnetic carbon material by zero-field nuclear magnetic resonance (NMR). Electronic structure calculations carried out in nanosized model systems with different classes of structural defects show a similar range of magnetic field values (18–21 T) for all investigated systems, in agreement with the NMR experiments. Our results are strong evidence of the intrinsic nature of defect-induced magnetism in magnetic carbons and establish the magnitude of the hyperfine magnetic field created in the neighbourhood of the defects that lead to magnetic order in these materials. PMID:26434597

  3. Field Dependence of the Magnetic Propagation Vector of the Heavy Fermion Compound CeCu2Ge2 Studied by Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Loewenhaupt, M.; Geselbracht, P.; Faulhaber, E.; Rotter, M.; Doerr, M.; Schmalzl, K.; Schneidewind, A.

    CeCu2Ge2, the counterpart of the heavy-fermion superconductor CeCu2Si2, exhibits an in-commensurate antiferromagnetically long-range ordered ground state with τ = (0.28 0.28 0.54) below TN = 4.15K. The magnetism is strongly affected by a Kondo screening of the Ce 4f-moments by conduction electrons. The similar energy scale of both, Kondo and exchange interactions, results in a complex magnetic phase diagram and gives rise to potential quantum critical phenomena at very low temperatures. We present elastic neutron diffraction data obtained on a CeCu2Ge2 single crystal employing the cold triple axis spectrometer PANDA at MLZ and the diffractometer D23 at ILL. The field dependence of the magnetic propagation vector was measured at T ≤ 400 mK in the [110]/[001] plane with vertical magnetic fields applied along [1¯10]. We observe a low-field incommensurate magnetic phase AF1, a first order phase transition around 7.8 T with the coexistence of two phases AF1 and AF2 with slightly different propagation vectors, the disappearance of AF1 at 8 T and the existence of AF2 up to 12 T with a possible modification at 10 T. At 12.6 T, yet still well below the value of 26 T of the saturation for magnetic fields in [110] direction, the AF2-type magnetic order is lost and magnetic intensities are not to be found at incommensurate positions in the [110]/[001] plane any more. These new results contradict a previously suggested scenario with a QCP located at 8 T and contribute new information to the B - T phase diagram of CeCu2Ge2 in [110] direction.

  4. The magnetized steel and scintillator calorimeters of the MINOS experiment

    SciTech Connect

    Michael, : D.G.

    2008-05-01

    The Main Injector Neutrino Oscillation Search (MINOS) experiment uses an accelerator-produced neutrino beam to perform precision measurements of the neutrino oscillation parameters in the 'atmospheric neutrino' sector associated with muon neutrino disappearance. This long-baseline experiment measures neutrino interactions in Fermilab's NuMI neutrino beam with a near detector at Fermilab and again 735 km downstream with a far detector in the Soudan Underground Laboratory in northern Minnesota. The two detectors are magnetized steel-scintillator tracking calorimeters. They are designed to be as similar as possible in order to ensure that differences in detector response have minimal impact on the comparisons of event rates, energy spectra and topologies that are essential to MINOS measurements of oscillation parameters. The design, construction, calibration and performance of the far and near detectors are described in this paper.

  5. A Fiber Interferometer for the Magnetized Shock Experiment

    SciTech Connect

    Yoo, Christian

    2012-08-30

    The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory requires remote diagnostics of plasma density. Laser interferometry can be used to determine the line-integrated density of the plasma. A multi-chord heterodyne fiber optic Mach-Zehnder interferometer is being assembled and integrated into the experiment. The advantage of the fiber coupling is that many different view chords can be easily obtained by simply moving transmit and receive fiber couplers. Several such fiber sets will be implemented to provide a time history of line-averaged density for several chords at once. The multiple chord data can then be Abel inverted to provide radially resolved spatial profiles of density. We describe the design and execution of this multiple fiber interferometer.

  6. The superconducting magnet system for the Tokamak Physics Experiment

    SciTech Connect

    Lang, D.D.; Bulmer, R.J.; Chaplin, M.R.

    1994-06-18

    The superconducting magnet system for the Tokamak Physics experiment (TPX) will be the first all superconducting magnet system for a Tokamak, where the poloidal field coils, in addition to the toroidal field coils are superconducting. The magnet system is designed to operate in a steady state mode, and to initiate the plasma discharge ohmically. The toroidal field system provides a peak field of 4.0 Tesla on the plasma axis at a plasma major radius of 2.25 m. The peak field on the niobium 3-tin, cable-in-conduit (CIC) conductor is 8.4 Tesla for the 16 toroidal field coils. The toroidal field coils must absorb approximately 5 kW due to nuclear heating, eddy currents, and other sources. The poloidal field system provides a total of 18 volt seconds to initiate the plasma and drive a plasma current up to 2 MA. The poloidal field system consists of 14 individual coils which are arranged symmetrically above and below the horizontal mid plane. Four pairs of coils make up the central solenoid, and three paris of poloidal ring coils complete the system. The poloidal field coils all use a cable-in-conduit conductor, using either niobium 3-tin (NB{sub 3}Sn) or niobium titanium (NbTi) superconducting strands depending on the operating conditions for that coil. All of the coils are cooled by flowing supercritical helium, with inlet and outlet connections made on each double pancake. The superconducting magnet system has gone through a conceptual design review, and is in preliminary design started by the LLNL/MIT/PPPL collaboration. A number of changes have been made in the design since the conceptual design review, and are described in this paper.

  7. Stability of Magnetically Implode Liners for High Energy Density Experiments

    SciTech Connect

    Reinovsky, R.E.; Anderson, W.E.; Atchison, W.L.; Bartsch, R.R.; Clark, D.A.; Ekdahl, C.E.; Faehl, R.J.; Goforth, J.H.; Keinigs, R.K.; Lindemuth, I.R.; Morgan, D.; Rodriguez, G.; Tasker, D.G.; Trainor, R.J.; Shlachter, J.S.

    1998-10-18

    Magnetically imploded cylindrical metal shells (z-pinch liners) are attractive drivers for a wide variety of hydrodynamics and material properties experiments. The ultimate utility of liners depends on the acceleration of near-solid density shells to velocities exceeding 20 km/sec with good azimuthal symmetry and axial uniformity. Two pulse power systems (Ranchero and Atlas) currently operational or under development at Los Alamos provide electrical energy adequate to accelerate {approximately}50 gr. liners to 1-2 MJ/cm kinetic energy. As in all z-pinches, the outer surface of a magnetically imploded liner is unstable to magneto-Rayleigh-Taylor (RT) modes during acceleration. Large-scale distortion in the liners from RT modes growing from glide plane interactions or initial imperfections could make liners unusable for man experiments. On the other hand, material strength in the liner should, from first principles, reduce the growth rate of RT modes - and can render some combinations of wavelength and amplitude analytically stable. The growth of instabilities in both soft aluminum liners and in high strength aluminum alloy liners has been studied analytically, computationally and experimentally at liner kinetic energies up to 100 KJ/cm on the Pegasus capacitor bank using driving currents up to 12 MA.

  8. Recent Results from the PVLAS Experiment on the Magnetized Vacuum

    NASA Astrophysics Data System (ADS)

    Cantatore, Giovanni

    The vacuum element can be used as a target in a photon-photon collider in order to study its properties. Some of these properties are predicted by Quantum Electrodynamics, while additional and unexpected properties might be linked to the existence of yet undiscovered axion-like particles (ALPs) interacting with two photons. In this low energy case (1 2 texteV), real photons from a polarized laser beam are scattered off virtual photons provided by a magnetic field. Information on the scattering processes can be obtained by measuring changes in the polarization state of the probe photons. In the PVLAS (Polarizzazione del Vuoto con LASer) experiment, running at the Legnaro Laboratory of the Istituto Nazionale di Fisica Nucleare (INFN), near Padova, Italy, a linearly polarized laser beam is sent through a 5 textT strong magnetic field in vacuum, where it is reflected back and forth, by means of a Fabry-P’erot resonator, ˜ 50,000 times over a distance of 1 textm. A heterodyne ellipsometer allows the simultaneous detection of a birefringence and a rotation of the polarization plane. The sensitivity of the instrument allows the detection of rotation or of ellipticity angles of about 10-9 textrad, in an hour of data taking. The measurement technique employed by PVLAS will be illustrated, and recent results on polarization effects due to the magnetized vacuum will be presented in this chapter. The interpretation of these effects in terms of the production of ALPs will also be discussed. Finally, the realization of a photon-regeneration type experiment will be briefly illustrated.

  9. Electric-field-induced reorientation and flip in domain magnetization and light diffraction in an yttrium-iron-garnet/lead-zirconate-titanate bilayer

    NASA Astrophysics Data System (ADS)

    Zavislyak, I. V.; Sohatsky, V. P.; Popov, M. A.; Srinivasan, G.

    2013-04-01

    A continuous reorientation and an abrupt flip to a canted structure in the magnetization of stripe domains are observed under the influence of an electric field in an yttrium-iron-garnet (YIG)/lead-zirconate-titanate (PZT) bilayer. Magneto-optic techniques have been utilized for the observation of the domain structure and the magnetization flip. It is found that electrically generated mechanical stress in PZT induces an uniaxial anisotropy field in YIG, which is large enough to initially cause a gradual change in the domain magnetization and then a transition from out-of-plane orientation to a canted state for a threshold electric field. Additional evidence for the spin flip has been obtained from data on the modulation of intensity of linearly polarized light due to diffraction by the stripe domains. A comprehensive theory for the voltage-induced magnetization flip is discussed and compared with the data. The magnetic transitions and the theory discussed here are of interests for electric-field-controlled magneto-optic and spintronic devices.

  10. Neutron and X-Ray Diffraction Studies of Magnetic Order in Uranium-Based Heavy Fermion Superconductors

    NASA Astrophysics Data System (ADS)

    Lussier, Jean-Guy

    UPt_3, URu_2 Si_2, UNi_2 Al_3 and UPd_2 Al_3 form a special group among the uranium alloys because they exhibit heavy fermion character, magnetic order and superconductivity. This main interest in the study of this group of compounds resides in the simultaneous occurrence of magnetism and superconductivity at low temperature. Such a state could potentially involve an unconventional superconducting pairing mechanism, different from that contained in standard BCS theory. In this thesis, the magnetic states of three of these materials (URu_2Si _2, UNi_2Al _3 and UPd_2Al _3) is investigated with neutron and the relatively new resonant magnetic X-ray scattering techniques. The work presented here on URu_2Si _2 follows an earlier effort that demonstrated the applicabililty of the resonant X-ray technique to this weak magnetic system. Access to reciprocal space was extended in order to confirm the multipolar form of the resonant X-ray cross-section and to explore the limits of the technique compared to neutron scattering. The situation with the newly discovered UNi_2Al _3 and UPd_2Al _3 was different since their magnetic structure and phases needed first to be established. This task was achieved using two magnetic probes (neutron and X-ray scattering). Several magnetic order parameters in the normal and in the superconducting phase were also measured. The incommensurate magnetic order found in UNi_2Al_3 by neutron scattering constitutes the first observation of long range order in this compound. Other measurements on this compound provided some clues about the evolution of the magnetic structure in high magnetic fields.

  11. Substituent effect in 2-benzoylmethylenequinoline difluoroborates exhibiting through-space couplings. Multinuclear magnetic resonance, X-ray diffraction, and computational study.

    PubMed

    Zakrzewska, Anna; Kolehmainen, Erkki; Valkonen, Arto; Haapaniemi, Esa; Rissanen, Kari; Chęcińska, Lilianna; Ośmiałowski, Borys

    2013-01-10

    The series of nine 2-benzoylmethylenequinoline difluoroborates have been synthesized and characterized by multinuclear magnetic resonance, X-ray diffraction (XRD), and computational methods. The through-space spin-spin couplings between (19)F and (1)H/(13)C nuclei have been observed in solution. The NMR chemical shifts have been correlated to the Hammett substituent constants. The crystal structures of six compounds have been solved by XRD. For two derivatives the X-ray wave function refinement was performed to evaluate the character of bonds in the NBF(2)O moiety by topological and integrated bond descriptors.

  12. Neutron diffraction study of magnetic field induced behavior in the heavy Fermion Ce3Co4Sn13

    SciTech Connect

    Christianson, Andrew D; Goremychkin, E. A.; Gardner, J. S.; Kang, H. J.; Chung, J.-H.; Manuel, P.; Thompson, J. D.; Sarrao, J. L.; Lawrence, J. M.

    2008-01-01

    The specific heat of Ce3Co4Sn13 exhibits a crossover from heavy Fermion behavior with antiferromagnetic correlations at low field to single impurity Kondo behavior above 2 T. We have performed neutron diffraction measurements in magnetic fields up to 6 Tesla on single crystal samples. The (001) position shows a dramatic increase in intensity in field which appears to arise from static polarization of the 4f level and which at 0.14 K also exhibits an anomaly near 2T reflecting the crossover to single impurity behavior.

  13. Magnetic properties of GdT2Zn20 (T = Fe, Co) investigated by x-ray diffraction and spectroscopy

    DOE PAGES

    J. R. L. Mardegan; Fabbris, G.; Francoual, S.; Veiga, L. S. I.; Strempfer, J.; Haskel, D.; Ribeiro, R. A.; Avila, M. A.; Giles, C.

    2016-01-26

    In this study, we investigate the magnetic and electronic properties of the GdT2Zn20 (T=Fe and Co) compounds using x-ray resonant magnetic scattering (XRMS), x-ray absorption near-edge structure (XANES), and x-ray magnetic circular dichroism (XMCD). The XRMS measurements reveal that GdCo2Zn20 has a commensurate antiferromagnetic spin structure with a magnetic propagation vector →/τ = (12,12,12) below the Néel temperature (TN ~ 5.7 K). Only the Gd ions carry a magnetic moment forming an antiferromagnetic structure with magnetic representation Γ6. For the ferromagnetic GdFe2Zn20 compound, an extensive investigation was performed at low temperature and under magnetic field using XANES and XMCD. Amore » strong XMCD signal of about 12.5% and 9.7% is observed below the Curie temperature (TC ~ 85K) at the Gd L2 and L3 edges, respectively. In addition, a small magnetic signal of about 0.06% of the jump is recorded at the Zn K edge, suggesting that the Zn 4p states are spin polarized by the Gd 5d extended orbitals.« less

  14. Physics of forced magnetic reconnection in coaxial helicity injection experiments in National Spherical Torus Experiment

    SciTech Connect

    Ebrahimi, F.; Bhattacharjee, A.; Raman, R.; Hooper, E. B.; Sovinec, C. R.

    2014-05-15

    We numerically examine the physics of fast flux closure in transient coaxial helicity injection (CHI) experiments in National Spherical Torus Experiment (NSTX). By performing resistive Magnetohydrodynamics (MHD) simulations with poloidal injector coil currents held constant in time, we find that closed flux surfaces are formed through forced magnetic reconnection. Through a local Sweet-Parker type reconnection with an elongated current sheet in the injector region, closed flux surfaces expand in the NSTX global domain. Simulations demonstrate outflows approaching poloidally Alfvénic flows and reconnection times consistent with the Sweet-Parker model. Critical requirements for magnetic reconnection and flux closure are studied in detail. These primary effects, which are magnetic diffusivity, injector flux, injector flux footprint width, and rate of injector voltage reduction, are simulated for transient CHI experiments. The relevant time scales for effective reconnection are τ{sub V}<τ{sub rec}≈τ{sub A}√(S)(1+Pm){sup 1/4}<τ{sub R}, where τ{sub V} is the time for the injector voltage reduction, τ{sub A} is the poloidal Alfvén transit time, τ{sub R} is the global resistive diffusion time, and Pm and S are Prandtl and Lundquist numbers.

  15. Common Crystalline and Magnetic Structure of Superconducting A2Fe4Se5 (A=K,Rb,Cs,Tl) Single Crystals Measured Using Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Ye, F.; Chi, S.; Bao, Wei; Wang, X. F.; Ying, J. J.; Chen, X. H.; Wang, H. D.; Dong, C. H.; Fang, Minghu

    2011-09-01

    Single-crystal neutron diffraction studies on superconductors A2Fe4Se5, where A=Rb, Cs, (Tl, Rb), and (Tl, K) (Tc˜30K), uncover the same Fe vacancy ordered crystal structure and the same block antiferromagnetic order as in K2Fe4Se5. The Fe order-disorder transition occurs at TS=500-578K, and the antiferromagnetic transition at TN=471-559K with an ordered magnetic moment ˜3.3μB/Fe at 10 K. Thus, all recently discovered A intercalated iron selenide superconductors share the common crystalline and magnetic structure, which are very different from previous families of Fe-based superconductors, and constitute a distinct new 245 family.

  16. A neutron diffraction study of RMn2O5 multiferroics

    NASA Astrophysics Data System (ADS)

    Radaelli, P. G.; Chapon, L. C.

    2008-10-01

    The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.

  17. Simple Experiments to Help Students Understand Magnetic Phenomena

    ERIC Educational Resources Information Center

    Browne, Kerry; Jackson, David P.

    2007-01-01

    The principles of magnetism are a common topic in most introductory physics courses, yet curricular materials exploring the behavior of permanent magnets and magnetic materials are surprisingly rare in the literature. We reviewed the literature to see how magnetism is typically covered in introductory textbooks and curricula. We found that while…

  18. Simple models for the heating curve in magnetic hyperthermia experiments

    NASA Astrophysics Data System (ADS)

    Landi, G. T.

    2013-01-01

    The use of magnetic nanoparticles for magnetic hyperthermia cancer treatment is a rapidly developing field of multidisciplinary research. From the material's standpoint, the main challenge is to optimize the heating properties of the material while maintaining the frequency of the exciting field as low as possible to avoid biological side effects. The figure of merit in this context is the specific absorption rate (SAR), which is usually measured from calorimetric experiments. Such measurements, which we refer to as heating curves, contain a substantial amount of information regarding the energy barrier distribution of the sample. This follows because the SAR itself is a function of temperature, and reflect the underlying magneto-thermal properties of the system. Unfortunately, however, this aspect of the problem is seldom explored and, commonly, only the SAR at ambient temperature is extracted from the heating curve. In this paper we introduce a simple model capable of describing the entire heating curve via a single differential equation. The SAR enters as a forcing term, thus facilitating the use of different models for it. We discuss in detail the heating in the context of Néel relaxation and show that high anisotropy samples may present an inflection point related to the reduction of the energy barrier caused by the increase in temperature. Mono-disperse and poli-disperse systems are discussed in detail and a new alternative to compute the temperature dependence of the SAR from the heating curve is presented.

  19. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  20. The magnetic and neutron diffraction studies of La{sub 1−x}Sr{sub x}MnO{sub 3} nanoparticles prepared via molten salt synthesis

    SciTech Connect

    Kačenka, M.; Kaman, O.; Jirák, Z.; Maryško, M.; Veverka, P.; Veverka, M.; Vratislav, S.

    2015-01-15

    Series of single-phase La{sub 1−x}Sr{sub x}MnO{sub 3} nanoparticles (x=0.25−0.47) with the size of about 50 nm was prepared in molten NaNO{sub 2}. TEM evidenced well dispersed particles that are not interconnected by sintering bridges in contrast to traditional products. Interestingly, some reduction of the perovskite cell volume, particularly at higher Sr-contents, was detected by XRD. Moreover, reduced magnetization and decreased Curie temperature in comparison to sol–gel samples were observed. Neutron diffraction analysis of the as-prepared nanoparticles and several comparative samples with x=0.37 indicated that the anomalous behavior of studied particles probably originate in the overdoped outer shell. The overdoping might result from both the surface oxygen chemisorption and from an increased Sr concentration in the shell. By all means, the overdoping would lead to compressive surface stress, driving the x=0.37 ground state toward a mixture of FM and A-type AFM ordering as observed by neutron diffraction. - Graphical abstract: La{sub 1−x}Sr{sub x}MnO{sub 3} nanoparticles with the size of about 50 nm were prepared by newly established method in molten NaNO{sub 2}. TEM proved the formation of well-separated particles without sintering bridges, the major advantage over traditional preparation methods. - Highlights: • Series of La{sub 1−x}Sr{sub x}MnO{sub 3} nanoparticles was prepared by novel method in NaNO{sub 2} melt. • Lower magnetization and Curie temperature in comparison to sol–gel nanoparticles was observed. • Overdoping of outer shell was indicated by neutron diffraction and cerimetric titration. • Overdoping shifts La{sub 0.37}Sr{sub 0.63}MnO{sub 3} ground state to a mixture of FM and A-type AFM ordering.

  1. Simple shear experiments on magnetized wax-hematite samples

    NASA Astrophysics Data System (ADS)

    Cogné, Jean-Pascal; Canot-Laurent, Sandrine

    1992-08-01

    We present the results of a series of simple shear experiments on hematite-bearing paraffin wax samples. Homogeneous and continuous deformation was obtained up to a shear strain value of γ = 1.4, by deforming the samples in a temperature-controlled bath, and at a constant strain rate of 9 × 10-5 s-1. During deformation, henatite platelets progressively rotate, which has been checked by measuring the anisotropy of magnetic susceptibility (AMS). Pricipal susceptibility directions tend to paralled the corresponding principal strain directions, and AMS instensity increases with increasing strain. This supports the idea that the hematite population develops a preferred orientation by progressive rigid rotation within the paraffin matrix. Before each deformation step, an isothermal remanent magnetization (IRM) was given to the samples, within the λ1λ3 finite strain plane (the plane containing the shear direction, and normal to the shear plane), with various initial angles to the shear direction ranging from 0° to 180°. After each deformation step, the IRM was measured. I showed no deflection towards the λ2 finite strain direction. In contrast, it did show a systematic rotation within the λ1λ3 plane, always in the same sense as the rotation of strain axes (e.g. counterclockwise in sinistral shear). Furthermore, IRM deviation is of the same order of magnitude for each initial direction from 0° to 180°. This contradicts the passive model that has previously been shown to hold for IRM in coaxially deformed samples. Finally, we show that, in the shear strain range of out experiments (γ = 0 to 1.4), the deviation of IRM depends only on the shear value, and not on its initial direction, and that this deviation is equal to the rigid rotation angle of the shear strain tensor.

  2. Magnetic ordering in the pyrochlore Ho2CrSbO7 determined from neutron diffraction, and the magnetic properties of other RE2CrSbO7 phases (RE=Y, Tb, Dy, Er)

    NASA Astrophysics Data System (ADS)

    Whitaker, Mariana J.; Greaves, Colin

    2014-07-01

    The magnetic structure of the pyrochlore Ho2CrSbO7, which orders magnetically below 13 K, has been studied using neutron powder diffraction. Ho2CrSbO7 is found to form an “ordered spin-ice structure” where the magnetic moments are constrained along the 111 axes, but with a ferromagnetic moment in one direction. The Cr3+ ions order ferromagnetically and this is thought to lift the degeneracy of the x, y and z directions in the cubic structure causing the ferromagnetic component from the Ho3+ ions to align. The pyrochlores RE2CrSbO7 where RE=Y, Tb, Dy and Er have also been prepared and studied using SQUID magnetometry.

  3. Fraunhofer Diffraction and Polarization.

    ERIC Educational Resources Information Center

    Fortin, E.

    1979-01-01

    Describes an experiment for the intermediate undergraduate optics laboratory designed to illustrate simultaneously some aspects of the phenomena of diffraction; interference, coherence, apodization, the Fresnel-Arago law; as well as of the interrelations between these concepts. (HM)

  4. Fresnel Coherent Diffractive Imaging

    NASA Astrophysics Data System (ADS)

    Williams, G. J.; Quiney, H. M.; Dhal, B. B.; Tran, C. Q.; Nugent, K. A.; Peele, A. G.; Paterson, D.; de Jonge, M. D.

    2006-07-01

    We present an x-ray coherent diffractive imaging experiment utilizing a nonplanar incident wave and demonstrate success by reconstructing a nonperiodic gold sample at 24 nm resolution. Favorable effects of the curved beam illumination are identified.

  5. Reflectivity (visible and near IR), Moessbauer, static magnetic, and X ray diffraction properties of aluminum-substituted hematites

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Schulze, Darrell G.; Lauer, Howard V., Jr.; Agresti, David G.; Shelfer, Tad D.

    1992-01-01

    The effect of substituting iron by aluminum in polymorphs of Fe2O3 and FeOOH on their reflectivity characteristics was investigated by comparing data on visible and NIR reflectivities and on static magnetic, XRD, and Moessbauer properties for a family of aluminum-substituted hematites alpha-(Fe,Al)2O3, with compositions where the values of the Al/(Al+Fe) ratio were up to 0.61. Samples were prepared by oxidation of magnetite, dehydroxylation of goethite, and direct precipitation. The analytical methods used for obtaining diffuse reflectivity spectra (350-2200 nm), Moessbauer spectra, and static magnetic data are those described by Morris et al. (1989).

  6. Imaging transmission grating spectrometer for magnetic fusion experiments

    NASA Astrophysics Data System (ADS)

    Blagojević, B.; Stutman, D.; Finkenthal, M.; Moos, H. W.; Kaita, R.; Majeski, R.

    2003-03-01

    The Johns Hopkins Plasma Spectroscopy Group is developing a transmission grating based imaging spectrometer for the ultrasoft x-ray [(USXR), 10-300 Å] range. The spectrometer will be integrated into an impurity diagnostic package for magnetic fusion experiments, which provides time and space resolved information about radiation losses, Zeff profiles, and particle transport. The spectrometer has a simple layout, consisting of collimating and space resolving slits, a transmission grating, and a two-dimensional imaging USXR detector. We tested two types of detectors, a CsI coated multichannel plate and a phosphor P45 coated fiber optic plate, both with intensified charge-coupled-device image readout. The performance of the 5000 1/mm, 3:1 bar to open area ratio transmission grating has been evaluated in the laboratory using Kα lines from a Manson source and the emission from a Penning discharge. A prototype spectrometer equiped with the first type detector and optimized for 6 Å spectral resolution has been tested successfully on the CDX-U tokamak at the Princeton Plasma Physics Laboratory. A spectrometer using the second detector version has been developed for the NSTX spherical torus at Princeton. Spatially resolved spectra have been recorded with 25-250 ms time integration with both spectrometers. In both experiments, spectra are dominated by low-Z impurities, C, N, and O.

  7. The TCS Rotating Magnetic Field FRC Current-Drive Experiment

    SciTech Connect

    Hoffman, Alan J.; Guo, Houyang Y.; Slough, John T.; Tobin, Stephen J.; Schrank, Louis S.; Reass, William A.; Wurden, Glen A.

    2002-03-15

    Field-reversed configurations (FRCs) have extremely attractive reactor attributes because of their singly connected geometry. They have been created in theta-pinch devices, but being compact toroids and lacking a center hole, their toroidal current cannot be sustained by transformer action as in other toroidal configurations. A new device, the Translation, Confinement, and Sustainment (TCS) facility has been constructed to use rotating magnetic fields (RMFs) to build up and sustain the flux of hot FRCs formed by the normal theta-pinch method. RMF formation and sustainment of similar, but cold, pure poloidal field configurations have been demonstrated in devices called rotamaks, and RMF formation, but not sustainment, has been achieved in a smaller FRC facility called the Star Thrust Experiment (STX). Initial formation and sustainment have now been achieved in TCS, albeit still with cold (T{sub e} {approx} 50 eV) plasmas. Both the formation and final steady-state conditions are found to agree with newly developed analytic and numerical models for RMF flux buildup and sustainment inside a standard cylindrical flux conserver. The required plasma conditions (mainly resistivity but also density) can now be determined for the planned hot FRC, RMF flux buildup experiments and for eventual reactor conditions.

  8. Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

    SciTech Connect

    Thomas, Sarah A.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Vohra, Yogesh K.; Chesnut, Gary N.; Weir, Samuel T.; Tulk, Christopher A.; dos Santos, Antonio M.

    2013-06-11

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the ferromagnetic Curie temperature. The temperature of this ferromagnetic transition decreases from approximately 240 K at ambient pressure at a rate of –16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of ferromagnetic order is suppressed. Neutron diffraction measurements as a function of pressure at temperatures ranging from 90 K to 290 K confirm that the change of slope in the resistance is associated with the ferromagnetic ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. Furthermore, a change in ferromagnetic ordering as the pressure is increased above 3.6 GPa is correlated with the phase transition from the ambient hexagonal close packed (hcp) structure to an α-Sm type structure at high pressures.

  9. Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

    SciTech Connect

    Thomas, Sarah; Montgomery, Jeffrey M; Tsoi, Georgiy; Vohra, Yogesh; Chesnut, Gary Neal; Weir, S. T.; Tulk, Christopher A; Moreira Dos Santos, Antonio F

    2013-01-01

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare-earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic (FM) order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the FM Curie temperature. The temperature of this FM transition decreases at a rate of-16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of FM order is suppressed. The neutron diffraction measurements as a function of pressure at temperatures ranging from 90 to 290 K confirm that the change of slope in the resistance is associated with the FM ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. A disappearance of FM ordering was observed as the pressure is increased above 3.6 GPa and is correlated with the phase transition from the ambient hexagonal close packed structure to an -Sm-type structure at high pressures.

  10. Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

    DOE PAGES

    Thomas, Sarah A.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Vohra, Yogesh K.; Chesnut, Gary N.; Weir, Samuel T.; Tulk, Christopher A.; dos Santos, Antonio M.

    2013-06-11

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the ferromagnetic Curie temperature. The temperature of this ferromagnetic transition decreases from approximately 240 K at ambient pressure at a rate of –16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of ferromagnetic order is suppressed. Neutron diffraction measurements as a function ofmore » pressure at temperatures ranging from 90 K to 290 K confirm that the change of slope in the resistance is associated with the ferromagnetic ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. Furthermore, a change in ferromagnetic ordering as the pressure is increased above 3.6 GPa is correlated with the phase transition from the ambient hexagonal close packed (hcp) structure to an α-Sm type structure at high pressures.« less

  11. Neutron diffraction and electrical transport studies on magnetic ordering in terbium at high pressures and low temperatures

    NASA Astrophysics Data System (ADS)

    Thomas, Sarah A.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Vohra, Yogesh K.; Chesnut, Gary N.; Weir, Samuel T.; Tulk, Christopher A.; dos Santos, Antonio M.

    2013-08-01

    Neutron diffraction and electrical transport measurements have been carried out on the heavy rare-earth metal terbium at high pressures and low temperatures in order to elucidate the onset of ferromagnetic (FM) order as a function of pressure. The electrical resistance measurements show a change in slope as the temperature is lowered through the FM Curie temperature. The temperature of this FM transition decreases at a rate of-16.7 K/GPa up to a pressure of 3.6 GPa, at which point the onset of FM order is suppressed. The neutron diffraction measurements as a function of pressure at temperatures ranging from 90 to 290 K confirm that the change of slope in the resistance is associated with the FM ordering, since this occurs at pressures similar to those determined from the resistance results at these temperatures. A disappearance of FM ordering was observed as the pressure is increased above 3.6 GPa and is correlated with the phase transition from the ambient hexagonal close packed structure to an α-Sm-type structure at high pressures.

  12. Magnetic structure of the quasi-one-dimensional La3OsO7 as determined by neutron powder diffraction

    DOE PAGES

    Morrow, Ryan; Susner, Michael A.; Sumption, Michael D.; Woodward, Patrick M.

    2015-10-05

    Insulating 5d3 La3OsO7 and the isostructural hole-doped analog La2.8Ca0.2OsO7 that feature pseudo-one-dimensional zigzag chains of corner-sharing OsO6 octahedra were synthesized and their magnetic and electrical transport properties characterized. Both of these compounds are insulating antiferromagnets. Moreover, for long range magnetic order between the antiferromagnetic chains we determined with a propagation vector k = 1/2,1/2,1 and TN = 45 and 33 K the parent and doped materials. An Os5+ moment of 1.7(1)μB for La3OsO7 and 1.2(2)μB for La2.8Ca0.2OsO7 is refined. The long range magnetic structure is compared to the isostructural compounds La3RuO7 and La3MoO7, both of which adopt different magnetic structures.

  13. High Magnetic field generation for laser-plasma experiments

    SciTech Connect

    Pollock, B B; Froula, D H; Davis, P F; Ross, J S; Fulkerson, S; Bower, J; Satariano, J; Price, D; Glenzer, S H

    2006-05-01

    An electromagnetic solenoid was developed to study the effect of magnetic fields on electron thermal transport in laser plasmas. The solenoid, which is driven by a pulsed power system suppling 30 kJ, achieves magnetic fields of 13 T. The field strength was measured on the solenoid axis with a magnetic probe and optical Zeeman splitting. The measurements agree well with analytical estimates. A method for optimizing the solenoid design to achieve magnetic fields exceeding 20 T is presented.

  14. Computational modeling of joint U.S.-Russian experiments relevant to magnetic compression/magnetized target fusion (MAGO/MTF)

    SciTech Connect

    Sheehey, P.T.; Faehl, R.J.; Kirkpatrick, R.C.; Lindemuth, I.R.

    1997-12-31

    Magnetized Target Fusion (MTF) experiments, in which a preheated and magnetized target plasma is hydrodynamically compressed to fusion conditions, present some challenging computational modeling problems. Recently, joint experiments relevant to MTF (Russian acronym MAGO, for Magnitnoye Obzhatiye, or magnetic compression) have been performed by Los Alamos National Laboratory and the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF). Modeling of target plasmas must accurately predict plasma densities, temperatures, fields, and lifetime; dense plasma interactions with wall materials must be characterized. Modeling of magnetically driven imploding solid liners, for compression of target plasmas, must address issues such as Rayleigh-Taylor instability growth in the presence of material strength, and glide plane-liner interactions. Proposed experiments involving liner-on-plasma compressions to fusion conditions will require integrated target plasma and liner calculations. Detailed comparison of the modeling results with experiment will be presented.

  15. Study of the magnetic and electronic properties of nanocrystalline PrCo3 by neutron powder diffraction and density functional theory.

    PubMed

    Younsi, Khedidja; Crivello, Jean-Claude; Paul-Boncour, Valérie; Bessais, Lotfi; Porcher, Florence; André, Gilles

    2013-03-20

    Nanocrystalline PrCo(3) powder has been synthesized by high-energy milling and was subsequently annealed from 873 to 1273 K for 30 min to optimize the extrinsic properties. The structure and magnetic properties of the nanocrystalline PrCo(3) have been investigated by means of x-ray and neutron diffraction as well as magnetization measurements. All compounds crystallize in the same PuNi(3) type structure, with grain sizes between 28 and 47 nm. As the annealing temperature increases, a maximum coercive field of 12 kOe at 300 K (55 kOe at 10 K) was obtained by annealing at 1023 K for a grain size of 35 nm. The refinement of the neutron powder diffraction patterns (NPD) of PrCo(3) from 1.8 to 300 K shows an expansion of the parameter a and a contraction of the parameter c, leading to a decrease of the ratio c/a. The evolution of the Co and Pr magnetic sublattices measured by NPD indicates that this compound is a highly anisotropic uniaxial ferromagnet with the easy magnetization axis parallel to c(-->). This experimental study has been completed by a theoretical investigation of the electronic structure of the PrCo(x) (x = 2, 3 and 5) compounds. Band structure calculations with collinear spin polarization were performed by using the local approximation of the density functional theory scheme implemented in the projector-augmented wave method. The electronic structure of PrCo(3) compound in both directions of spin shows that the majority of occupied states are dominated by the 3d states of Co, with a strong electronic charge transfer from Pr to Co. The PrCo(3) electronic structure can be explained by a superimposition of those of PrCo(2) and PrCo(5), as expected from its crystal structure. The magnetic anisotropy has been confirmed for PrCo(3), as a non-collinear spin calculation with the polarization along the c axis is shown to be more stable than with the polarization in the (a(-->),b(-->)) plane.

  16. Scaling experiments on a magnetically insulated thermionic vacuum switch

    SciTech Connect

    Eninger, J.E.; Vanderberg, B.H.

    1994-12-31

    Magnetic insulation of the electron flow in a cylindrical thermionic vacuum diode has been proposed as a way to achieve a fast high-voltage high-power opening switch. The expected performance of this type of device can be derived from a set of basic scaling laws combined with empirical relationships obtained from experimental studies. Switch losses are mainly due to anode dissipation W{sub a}, which can be normalized to the transferred pulse energy. Leakage current and switch hold-off voltage depend on device geometry, materials, vacuum conditions etc and must be determined experimentally. For this purpose, the MX-1 experiment has been designed and operated. This device is basically a smooth-bore cylindrical magnetron with a 5 cm radius, 400 cm{sup 2} area thermionic dispenser cathode separated from the coaxial water-cooled anode by a few mm wide gap. This design allows pulsed operation at up to {approximately}100 kV, {approximately}4 kA and average power levels of {approximately}1 MW. The MX-1 switch is used as an opening switch to produce 1--2 {mu}s long square pulses from an inductive storage PFN. The current-voltage characteristics of the switch are determined as a function of the applied magnetic field and load condition. Plasma wave measurements are performed to investigate the stability of the electron flow. Results are summarized in the form of scaling diagrams for the important switch parameters, showing possible performance levels and physical and technical limitations identified as far in this work.

  17. NEUTRON-DIFFRACTION STUDY ON PLASTIC BEHAVIOR OF A NICKEL-BASED ALLOY UNDER THE MONOTONIC-TENSION AND THE LOW-CYCLE-FATIGUE EXPERIMENTS

    SciTech Connect

    Huang, E-Wen; Barabash, Rozaliya; Clausen, Bjorn; Wang, Yandong; Yang, Dr Ren; Li, Li; Choo, Hahn; Liaw, Peter K

    2007-01-01

    The plastic behavior of an annealed HASTELLOY C-22HS alloy, a face-centered cubic (FCC), nickel-based superalloy, was examined by in-situ neutron-diffraction measurements at room temperature. Both monotonic-tension and low-cycle-fatigue experiments were conducted. Monotonic-tension straining and cyclic-loading deformation were studied as a function of stress. The plastic behavior during deformation is discussed in light of the relationship between the stress and dislocation-density evolution. The calculated dislocation-density evolution within the alloy reflects the strain hardening and cyclic hardening/softening. Experimentally determined lattice strains are compared to verify the hardening mechanism at selected stress levels for tension and cyclic loadings. Combined with calculations of the dislocation densities, the neutron-diffraction experiments provide direct information about the strain and cyclic hardening of the alloy.

  18. Neutron Diffraction Study on Plastic behavior of a Nickel-Based Alloy Under the Monotonic-Tension and the Low-Cyclic-Fatigue Experiments

    SciTech Connect

    Huang, E.-W.; Barabash, R.; Clausen, B.; Wang, Y.; Yang, R.; Li, L.; Choo, H.; Liaw, P.K.

    2007-11-02

    The plastic behavior of an annealed HASTELLOY C-22HS alloy, a face-centered cubic (FCC), nickel-based superalloy, was examined by in-situ neutron-diffraction measurements at room temperature. Both monotonic-tension and low-cycle-fatigue experiments were conducted. Monotonic-tension straining and cyclic-loading deformation were studied as a function of stress. The plastic behavior during deformation is discussed in light of the relationship between the stress and dislocation-density evolution. The calculated dislocation-density evolution within the alloy reflects the strain hardening and cyclic hardening/softening. Experimentally determined lattice strains are compared to verify the hardening mechanism at selected stress levels for tension and cyclic loadings. Combined with calculations of the dislocation densities, the neutron-diffraction experiments provide direct information about the strain and cyclic hardening of the alloy.

  19. Evolution of structure and local magnetic fields during crystallization of HITPERM glassy alloys studied by in situ diffraction and nuclear forward scattering of synchrotron radiation.

    PubMed

    Miglierini, Marcel; Pavlovič, Márius; Procházka, Vít; Hatala, Tomáš; Schumacher, Gerhard; Rüffer, Rudolf

    2015-11-14

    Evolution of structure and local magnetic fields in (Fe(1-x)Co(x))76Mo8Cu1B15 (HITPERM) metallic glass ribbons with various amounts of Co (x = 0, 0.25, 0.5) were studied in situ using diffraction and nuclear forward scattering of synchrotron radiation. It was found that crystallization of all three glasses proceeds in two stages. In the first stage, bcc (Fe,Co) nanocrystals are formed, while in the second stage additional crystalline phases evolve. For all three glasses, the crystallization temperatures at the wheel side were found to be lower than at the air side of the ribbon. The crystallization temperatures were found to decrease with increasing Co content. The lattice parameters of the bcc nanocrystals decrease up to about 550 °C and then increase pointing to squeezing Mo atoms out of the nanograins or to interface effects between the nanocrystals and the glassy matrix. Nuclear forward scattering enabled separate evaluation of the contributions that stem from structurally different regions within the investigated samples including the newly formed nanocrystals and the residual amorphous matrix. Even minor Co content (x = 0.25) has a substantial effect not only upon the magnetic behaviour of the alloy but also upon its structure. Making use of hyperfine magnetic fields, it was possible to unveil structurally diverse positions of Fe atoms that reside in a nanocrystalline lattice with different numbers of Co nearest neighbours.

  20. Phononic crystal diffraction gratings

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

    2012-02-01

    When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

  1. Tools and Setups for Experiments with AC and Rotating Magnetic Fields

    ERIC Educational Resources Information Center

    Ponikvar, D.

    2010-01-01

    A rotating magnetic field is the basis for the transformation of electrical energy to mechanical energy. School experiments on the rotating magnetic field are rare since they require the use of specially prepared mechanical setups and/or relatively large, three-phase power supplies to achieve strong magnetic fields. This paper proposes several…

  2. The Magnetic Sentences Industry Game: A Competitive In-Class Experience of Business-Level Strategy

    ERIC Educational Resources Information Center

    Casile, Maureen; Wheeler, Jane V.

    2005-01-01

    The Magnetic Sentences Industry Game is a high-energy in-class exercise designed to help students gain hands-on experience with setting, implementing, evaluating, and revising business-level strategy. Students compete in teams to create and market sentences using Magnetic Poetry (a product of Magnetic Poetry, Inc.). Revenues earned are highly…

  3. Results of the Magnetic Properties Experiment on the Mars Exploration Rovers

    NASA Astrophysics Data System (ADS)

    Hviid, S. F.; Goetz, W.; Madsen, M. B.; Knudsen, J. M.; Bertelsen, P.; MER Science

    2004-11-01

    The two Mars Exploration Rovers each carry a set of Magnetic Properties Experiments (MPE) to investigate the properties of the air-borne dust in the Martian atmosphere. The goal of the MPE is to provide information on the processes that formed the dust (past and present). The objectives are: a) To identify the magnetic mineral(s) in the dust, soil and rocks on Mars. b) To establish if the magnetic material is present in the form of nanosized possibly superparamagnetic crystallites embedded in the micrometer sized airborne dust particles. c) To establish if the magnets are culling a subset of strongly magnetic particles or if essentially all particles of the airborne dust are sufficiently magnetic to be attracted by the magnets. d) Detect possible compositional differences between the airborne dust and the soil at the two landing sites. The MPE is composed of three major units: a) The Filter and Capture magnets. b) The Sweep Magnet and c) The RAT Magnets. The Filter and Capture magnets are designed to measure the elemental composition/iron mineralogy of the air-borne dust using the APX and Mössbauer Spectrometers and to investigate possible differences in trace element concentrations between the air-borne dust as a whole and the magnetic separate of the air-borne dust. The Sweep Magnet experiment is designed to serve two purposes: 1) Detect if any non-magnetic minerals are present in the atmospheric dust in any significant amount. 2) Provide a magnetically attracted dust layer suitable for spectroscopic investigation by the multispectral Panoramic Camera (PANCAM). The RAT magnet experiment is mounted inside the Rock Abrasion Tool (RAT) and is designed to detect the presence of magnetic grains released by the grinding process of rocks. A summary of the results of these experiments will be presented at the Assembly.

  4. Conformational isomerism in solid state of AMG 853--structure studies using solid-state nuclear magnetic resonance and X-ray diffraction.

    PubMed

    Kiang, Y-H; Nagapudi, Karthik; Wu, Tian; Peterson, Matthew L; Jona, Janan; Staples, Richard J; Stephens, Peter W

    2015-07-01

    Investigation of an additional resonance peak in the (19) F solid-state nuclear magnetic resonance (NMR) spectrum of AMG 853, a dual antagonist of DP and CRTH2 previously in clinical development for asthma, has led to the identification of two conformational isomers coexisting in the crystal lattice in a continuous composition range between 89.7%:10.3% and 96.5%:3.5%. These two isomers differ in the chloro-flurorophenyl moiety orientation-the aromatic ring is flipped by 180° in these two isomers. The level of the minor isomer is directly measured through integration of the two peaks in the (19) F solid-state NMR spectrum. The values obtained from the NMR data are in excellent agreement with the degree of disorder of the fluorine atom in the crystal structure, refined using both single-crystal and high-resolution powder X-ray diffraction data.

  5. Thermal and magnetic anomalies of α-iron: an exploration by extended x-ray absorption fine structure spectroscopy and synchrotron x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Boccato, Silvia; Sanson, Andrea; Kantor, Innokenty; Mathon, Olivier; Dyadkin, Vadim; Chernyshov, Dmitry; Carnera, Alberto; Pascarelli, Sakura

    2016-09-01

    The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibrational dynamics of α-iron: the second neighbor distance exhibits anharmonicity and vibrational anisotropy larger than the first neighbor distance. We search for possible distortions of the bcc structure to justify the unexplained magnetostriction anomalies of α-iron and provide a value for the maximum dislocation of the central Fe atom. No thermal anomalies have been detected from the current XRD data. On the contrary, an intriguing thermal anomaly at about 150 K, ascribed to a stiffening of the Fe–Fe bonds, was found by EXAFS.

  6. Thermal and magnetic anomalies of α-iron: an exploration by extended x-ray absorption fine structure spectroscopy and synchrotron x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Boccato, Silvia; Sanson, Andrea; Kantor, Innokenty; Mathon, Olivier; Dyadkin, Vadim; Chernyshov, Dmitry; Carnera, Alberto; Pascarelli, Sakura

    2016-09-01

    The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibrational dynamics of α-iron: the second neighbor distance exhibits anharmonicity and vibrational anisotropy larger than the first neighbor distance. We search for possible distortions of the bcc structure to justify the unexplained magnetostriction anomalies of α-iron and provide a value for the maximum dislocation of the central Fe atom. No thermal anomalies have been detected from the current XRD data. On the contrary, an intriguing thermal anomaly at about 150 K, ascribed to a stiffening of the Fe-Fe bonds, was found by EXAFS.

  7. Thermal and magnetic anomalies of α-iron: an exploration by extended x-ray absorption fine structure spectroscopy and synchrotron x-ray diffraction.

    PubMed

    Boccato, Silvia; Sanson, Andrea; Kantor, Innokenty; Mathon, Olivier; Dyadkin, Vadim; Chernyshov, Dmitry; Carnera, Alberto; Pascarelli, Sakura

    2016-09-01

    The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibrational dynamics of α-iron: the second neighbor distance exhibits anharmonicity and vibrational anisotropy larger than the first neighbor distance. We search for possible distortions of the bcc structure to justify the unexplained magnetostriction anomalies of α-iron and provide a value for the maximum dislocation of the central Fe atom. No thermal anomalies have been detected from the current XRD data. On the contrary, an intriguing thermal anomaly at about 150 K, ascribed to a stiffening of the Fe-Fe bonds, was found by EXAFS.

  8. Nuclear magnetic resonance experiments with dc SQUID amplifiers

    SciTech Connect

    Heaney, M.B. . Dept. of Physics Lawrence Berkeley Lab., CA )

    1990-11-01

    The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

  9. Magnetic resonance imaging of the female pelvis: initial experience

    SciTech Connect

    Hricak, H.; Alpers, C.; Crooks, L.E.; Sheldon, P.E.

    1983-12-01

    The potential of magnetic resonance imaging (MRI) was evaluated in 21 female subjects: seven volunteers, 12 patients scanned for reasons unrelated to the lower genitourinary tract, and two patients referred with gynecologic disease. The uterus at several stages was examined; the premenarcheal uterus (one patient), the uterus of reproductive age (12 patients), the postmenopausal uterus (two patients), and in an 8 week pregnancy (one patient). The myometrium and cyclic endometrium in the reproductive age separated by a low-intensity line (probably stratum basale), which allows recognition of changes in thickness of the cyclic endometrium during the menstrual cycle. The corpus uteri can be distinguished from the cervix by the transitional zone of the isthmus. The anatomic relation of the uterus to bladder and rectum is easily outlined. The vagina can be distinguished from the cervix, and the anatomic display of the closely apposed bladder, vagina, and rectum is clear on axial and coronal images. The ovary is identified; the signal intensity from the ovary depends on the acquisition parameter used. Uterine leiomyoma, endometriosis, and dermoid cyst were depicted, but further experience is needed to ascertain the specificity of the findings.

  10. The X-ray diffraction study of three-dimensional disordered network of nanographites: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Saenko, N. S.

    The average sizes of nanographites (the structure units of activated carbon fibers) have been determined by fitting experimental X-ray diffraction profile by theoretical curves, calculated using Warren-Bodenstein equations. The structure parameters of nanographites obtained by this way are different from ones determined by standard Scherrer equation. The result indicates that the shape factor of the Scherrer equation for the considered ensemble of nanographites differs from generally accepted value.

  11. An X-ray diffraction, magnetic susceptibility and spectroscopic studies of Yb{sub 2-x}Cr{sub x}O{sub 3}

    SciTech Connect

    Hamdi, S.; Amami, M.; Hlil, E.K.; Ben Hassen, R.

    2011-07-15

    Polycrystalline samples with general formula Yb{sub 2-x}Cr{sub x}O{sub 3} (0diffraction, formed solid solutions over all the mentioned range. Cr showed a maximum solubility of 2.8 mol% in Yb{sub 2}O{sub 3} sesquioxide at 1000 deg. C. A preferential substitution of Cr{sup 3+} ions over two cationic sites, 8b and 24d in the space group Ia-3 was found. The lattice parameters a are found to vary linearly (10.4402(4) A Magnetic susceptibility measurements of all samples were done in a temperature range of 2-50 K. For T<37 K, the inverse paramagnetic susceptibilities depend linearly on temperature. However, in the high-temperature region, for T>37 K, the inverse paramagnetic susceptibilities are non-linear versus temperature. This deviation from the Curie-Weiss behaviour was discussed. - Graphical abstract: The least square fit to the modified Curie-Weiss law shows paramagnetic interaction in Yb{sub 2-x}Cr{sub x}O{sub 3} (0magnetic properties of the samples with x>0.03 Highlights: > We described our attempts to synthesize Yb{sub 2-x}Cr{sub x}O{sub 3} series of compounds.{yields} The products were characterized by X-ray diffraction, Raman and magnetic measurements. > Cr showed a maximum solubility of 2.8 mol% in Yb{sub 2}O{sub 3} sesquioxide at 1000 deg. C. > The least square fit to the modified Curie-Weiss law shows paramagnetic interaction. > The Yb

  12. Comparative analysis of ex-situ and operando X-ray diffraction experiments for lithium insertion materials

    NASA Astrophysics Data System (ADS)

    Brant, William R.; Li, Dan; Gu, Qinfen; Schmid, Siegbert

    2016-01-01

    A comparative study of ex-situ and operando X-ray diffraction techniques using the fast lithium ion conductor Li0.18Sr0.66Ti0.5Nb0.5O3 is presented. Ex-situ analysis of synchrotron X-ray diffraction data suggests that a single phase material exists for all discharges to as low as 0.422 V. For samples discharged to 1 V or lower, i.e. with higher lithium content, it is possible to determine the lithium position from the X-ray data. However, operando X-ray diffraction from a coin cell reveals that a kinetically driven two phase region occurs during battery cycling below 1 V. Through monitoring the change in unit cell dimension during electrochemical cycling the dynamics of lithium insertion are explored. A reduction in the rate of unit cell expansion of 22(2)% part way through the first discharge and 13(1)% during the second discharge is observed. This reduction may be caused by a drop in lithium diffusion into the bulk material for higher lithium contents. A more significant change is a jump in the unit cell expansion by 60(2)% once the lithium content exceeds one lithium ion per vacant site. It is suggested that this jump is caused by damping of octahedral rotations, thus establishing a link between lithium content and octahedral rotations.

  13. Neutron diffraction study of the magnetic structures of CeMn{sub 2}Ge{sub 2} and CeMn{sub 2}Si{sub 2}

    SciTech Connect

    Fernandez-Baca, J.A.; Chakoumakos, B.C.; Hill, P.; Ali, N.

    1995-12-31

    The magnetic properties of the layered compounds of the form RMn{sub 2}X{sub 2} (R = Rare Earth, X = Si, Ge) have been thought to be sensitive to the intralayer Mn-Mn distance. Thus it has been reported that the Mn moments in CeMn{sub 2}Si{sub 2} are aligned antiferromagnetically (AF) below T{sub N} = 380K, while the Mn moments in CeMn{sub 2}Ge{sub 2} are ferromagnetic (FM) below T{sub C} = 316K. Recently, however, there has been some debate about the actual magnetic structures of this family of compounds, and for this reason the authors have performed high-resolution neutron powder diffraction measurements on these compounds for temperatures between 12K and 550K. The measurements indicate that at high temperatures both compounds are paramagnetic. Below T{sub N} = 380K CeMn{sub 2}Si{sub 2} becomes a collinear AF, with a structure similar to that reported by Siek et al. in which the magnetic propagation vector is {tau} = (0 0 1). CeMn{sub 2}Ge{sub 2} on the other hand, exhibits two different magnetic transitions. At T{sub N} {approx} 415K there is a transition to a collinear AF phase characterized by the commensurate propagation wavevector {tau} = (1 0 1). At T{sub C} = 318K there is a transition to a conical structure with a ferromagnetic component along the c-axis and a helical component in the ab plane. The helical component is characterized by the incommensurate propagation vector {tau} = (1 0 1-q{sub z}), where q{sub z} is temperature dependent. These findings are consistent with the recent results of Welter et al.

  14. Computation of diffuse scattering arising from one-phonon excitations in a neutron time-of-flight single-crystal Laue diffraction experiment

    PubMed Central

    Gutmann, Matthias J.; Graziano, Gabriella; Mukhopadhyay, Sanghamitra; Refson, Keith; von Zimmerman, Martin

    2015-01-01

    Direct phonon excitation in a neutron time-of-flight single-crystal Laue diffraction experiment has been observed in a single crystal of NaCl. At room temperature both phonon emission and excitation leave characteristic features in the diffuse scattering and these are well reproduced using ab initio phonons from density functional theory (DFT). A measurement at 20 K illustrates the effect of thermal population of the phonons, leaving the features corresponding to phonon excitation and strongly suppressing the phonon annihilation. A recipe is given to compute these effects combining DFT results with the geometry of the neutron experiment. PMID:26306090

  15. Initial Results from the Magnetized Dusty Plasma Experiment (MDPX)

    NASA Astrophysics Data System (ADS)

    Thomas, Edward; Konopka, Uwe; Lynch, Brian; Adams, Stephen; Leblanc, Spencer; Artis, Darrick; Dubois, Ami; Merlino, Robert; Rosenberg, Marlene

    2014-10-01

    The MDPX device is envisioned as a flexible, multi-user, research instrument that can perform a wide range of studies in fundamental and applied plasma physics. The MDPX device consists of two main components. The first is a four-coil, open bore, superconducting magnet system that is designed to produce uniform magnetic fields of up to 4 Tesla and non-uniform magnetic fields with gradients up to up to 2 T/m configurations. Within the warm bore of the magnet is placed an octagonal vacuum chamber that has a 46 cm outer diameter and is 22 cm tall. The primary missions of the MDPX device are to: (1) investigate the structural, thermal, charging, and collective properties of a plasma as the electrons, ions, and finally charged microparticles become magnetized; (2) study the evolution of a dusty plasma containing magnetic particles (paramagnetic, super-paramagnetic, or ferromagnetic particles) in the presence of uniform and non-uniform magnetic fields; and, (3) explore the fundamental properties of strongly magnetized plasmas (``i.e., dust-free'' plasmas). This presentation will summarize the initial characterization of the magnetic field structure, initial plasma parameter measurements, and the development of in-situ and optical diagnostics. This work is supported by funding from the NSF and the DOE.

  16. X-ray diffraction study of the optimization of MgO growth conditions for magnetic tunnel junctions

    SciTech Connect

    O, Se Young; Lee, Chan-Gyu; Shapiro, Alexander J.; Egelhoff, William F. Jr.; Mallett, Jonathan; Pong, Philip W. T.; Vaudin, Mark D.; Ruglovsky, Jennifer L.

    2008-04-01

    We have carried out a systematic study optimizing the MgO growth via preparation and sputtering conditions and underlayer structures. It was found that to prevent water vapor which is detrimental to MgO (200) growth, the chamber pressure needs to be reduced below 10{sup -8} Torr. Simple underlayers such as 5 nm CoFeB tend to give better MgO, but we have also succeeded in growing MgO on more complicated underlayers such as 1 Ta/20 Au/5 Co{sub 40}Fe{sub 40}B{sub 20} and 1 Ta/20 conetic (Ni{sub 77}Fe{sub 14}Cu{sub 5}Mo{sub 4})/1.5 Co{sub 40}Fe{sub 40}B{sub 20} (units in nanometers). We accomplished this by extensive baking of the deposition chamber and use of Ti-getter films. Short sputtering distance and high sputtering power were found to optimize MgO deposition. We found that both preparation and sputtering conditions have important effects on the MgO growth. X-ray diffraction analysis was used as the characterization tool for optimizing the MgO growth conditions.

  17. Refinement of atomic and magnetic structures using neutron diffraction for synthesized bulk and nano-nickel zinc gallate ferrite

    NASA Astrophysics Data System (ADS)

    Ata-Allah, S. S.; Balagurov, A. M.; Hashhash, A.; Bobrikov, I. A.; Hamdy, Sh.

    2016-01-01

    The parent NiFe2O4 and Zn/Ga substituted spinel ferrite powders have been prepared by solid state reaction technique. As a typical example, the Ni0.7Zn0.3Fe1.5Ga0.5O4 sample has been prepared by sol-gel auto combustion method with the nano-scale crystallites size. X-ray and Mössbauer studies were carried out for the prepared samples. Structure and microstructure properties were investigated using the time-of-flight HRFD instrument at the IBR-2 pulsed reactor, at a temperatures range 15-473 K. The Rietveld refinement of the neutron diffraction data revealed that all samples possess cubic symmetry corresponding to the space group Fd3m. Cations distribution show that Ni2+ is a complete inverse spinel ion, while Ga3+ equally distributed between the two A and B-sublattices. The level of microstrains in bulk samples was estimated as very small while the size of coherently scattered domains is quite large. For nano-structured sample the domain size is around 120 Å.

  18. Meta-Stable Magnetic Domain States That Prevent Reliable Absolute Palaeointensity Experiments Revealed By Magnetic Force Microscopy

    NASA Astrophysics Data System (ADS)

    de Groot, L. V.; Fabian, K.; Bakelaar, I. A.; Dekkers, M. J.

    2014-12-01

    Obtaining reliable estimates of the absolute palaeointensity of the Earth's magnetic field is notoriously difficult. Many methods to obtain paleointensities from suitable records such as lavas and archeological artifacts involve heating the samples. These heating steps are believed to induce 'magnetic alteration' - a process that is still poorly understood but prevents obtaining correct paleointensity estimates. To observe this magnetic alteration directly we imaged the magnetic domain state of titanomagnetite particles - a common carrier of the magnetic remanence in samples used for paleointensity studies. We selected samples from the 1971-flow of Mt. Etna from a site that systematically yields underestimates of the known intensity of the paleofield - in spite of rigorous testing by various groups. Magnetic Force Microscope images were taken before and after a heating step typically used in absolute palaeointensity experiments. Before heating, the samples feature distinct, blocky domains that sometimes seem to resemble a classical magnetite domain structure. After imparting a partial thermo-remanent magnetization at a temperature often critical to paleointensity experiments (250 °C) the domain state of the same titanomagnetite grains changes into curvier, wavy domains. Furthermore, these structures appeared to be unstable over time: after one-year storage in a magnetic field-free environment the domain states evolved into a viscous remanent magnetization state. Our observations may qualitatively explain reported underestimates from technically successful paleointensity experiments for this site and other sites reported previously. Furthermore the occurrence of intriguing observations such as 'the drawer storage effect' by Shaar et al (EPSL, 2011), and viscous magnetizations observed by Muxworthy and Williams (JGR, 2006) may be (partially) explained by our observations. The major implications of our study for all palaeointensity methods involving heating may be

  19. Superconducting magnets and devices for space vehicles and experiments

    NASA Technical Reports Server (NTRS)

    Urban, E. W.

    1971-01-01

    Superconductivity research has been oriented toward those problems that tend to restrict the greater application of superconducting devices in space research and technology. These include magnetic problems of high field magnets, increasing operating temperatures, and development of useful competitive superconducting instruments.

  20. X-ray Diffraction, Mössbauer Spectroscopy, Magnetic Susceptibility, and Specific Heat Investigations of Na4NpO5 and Na5NpO6.

    PubMed

    Smith, Anna L; Hen, Amir; Raison, Philippe E; Colineau, Eric; Griveau, Jean-Christophe; Magnani, Nicola; Sanchez, Jean-Pierre; Konings, Rudy J M; Caciuffo, Roberto; Cheetham, Anthony K

    2015-05-01

    The hexavalent and heptavalent sodium neptunate compounds Na4NpO5 and Na5NpO6 have been investigated using X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, and specific heat measurements. Na4NpO5 has tetragonal symmetry in the space group I4/m, while Na5NpO6 adopts a monoclinic unit cell in the space group C2/m. Both structures have been refined for the first time using the Rietveld method. The valence states of neptunium in these two compounds, i.e., Np(VI) and Np(VII), respectively, have been confirmed by the isomer shift values of their Mössbauer spectra. The local structural properties obtained from the X-ray refinements have also been related to the quadrupole coupling constants and asymmetry parameters determined from the Mössbauer studies. The absence of magnetic ordering has been confirmed for Na4NpO5. However, specific heat measurements at low temperatures have suggested the existence of a Schottky-type anomaly at around 7 K in this Np(VI) phase. PMID:25859629

  1. Magnetic ground state of superconducting Eu (Fe 0.88Ir 0.12)2As 2: A combined neutron diffraction and first-principles calculation study

    NASA Astrophysics Data System (ADS)

    Jin, W. T.; Li, Wei; Su, Y.; Nandi, S.; Xiao, Y.; Jiao, W. H.; Meven, M.; Sazonov, A. P.; Feng, E.; Chen, Yan; Ting, C. S.; Cao, G. H.; Brückel, Th.

    2015-02-01

    The magnetic order of the localized Eu2 + spins in optimally doped Eu (Fe1 -xIrx )2As2 (x =0.12 ) with superconducting transition temperature TSC=22 K was investigated by single-crystal neutron diffraction. The Eu2 + moments were found to be ferromagnetically aligned along the c direction with an ordered moment of 7.0(1) μB well below the magnetic phase transition temperature TC=17 K. No evidence of the tetragonal-to-orthorhombic structural phase transition was found in this compound within the experimental uncertainty, in which the spin-density-wave (SDW) order of the Fe sublattice is supposed to be completely suppressed and the superconductivity gets fully developed. The ferromagnetic ground state of the Eu2 + spins in Eu (Fe0.88Ir0.12 )2As2 was supported by the first-principles density functional calculation. In addition, comparison of the electronic structure calculations between Eu (Fe0.875Ir0.125 )2As2 and the parent compound EuFe2As2 indicates stronger hybridization and more expanded bandwidth due to the Ir substitution, which together with the introduction of electrons might work against the Fe-SDW in favor of the superconductivity.

  2. Neutron diffraction studies on chemical and magnetic structure of multiferroic PbFe{sub 0.67}W{sub 0.33}O{sub 3}

    SciTech Connect

    Matteppanavar, Shidaling Angadi, Basavaraj; Rayaprol, Sudhindra

    2014-04-24

    We report on the single phase synthesis and room temperature structural characterization of PbFe{sub 0.67}W{sub 0.33}O{sub 3} (PFW) multiferroic. The PFW was synthesized by low temperature sintering, Columbite method. Analysis of powder XRD pattern exhibits single phase formation of PFW with no traces of pyrochlore phase. Detailed analysis of room temperature neutron diffraction (ND) reveals cubic phase at room temperature, space group Pm-3m. The ND pattern clearly reveals magnetic Bragg peak at 2θ = 18.51° (Q = 1.36Å{sup −1}). The refinement of magnetic structure reveals G-type antiferromagnetic structure in PFW at room temperature. The dielectric constant and loss tangent decreases with increasing frequency. The room temperature P-E measurements shows a non-linear slim hysteresis, typical nature of relaxor multiferroics, with saturation and remnant polarizations of P{sub s} = 1.50 μC/cm{sup 2} and P{sub r} = 0.40 μC/cm{sup 2}, respectively.

  3. Active experiments in space in conjunction with Skylab. [barium plasma injection experiment and magnetic storm of March 7, 1972

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.

    1974-01-01

    Two papers are presented which relate to the Skylab barium shaped charge experiments. The first describes the L=6.6 OOSIK barium plasma injection experiment and magnetic storm of March 7, 1972. Rocket payload, instrumentation, data reduction methods, geophysical environment at the time of the experiment, and results are given. The second paper presents the observation of an auroral Birkeland current which developed from the distortion of a barium plasma jet during the above experiment.

  4. Sr{sub 4}Ru{sub 6}ClO{sub 18}, a new Ru{sup 4+/5+} oxy-chloride, solved by precession electron diffraction: Electric and magnetic behavior

    SciTech Connect

    Roussel, Pascal; Palatinus, Lukas; Belva, Frédéric; Daviero-Minaud, Sylvie; Mentre, Olivier; Huve, Marielle

    2014-04-01

    The crystal structure of Sr{sub 4}Ru{sub 6}ClO{sub 18}, a new Ru{sup 4+/5+} oxo-chloride, has been determined from Precession Electron Diffraction (PED) data acquired on a nanocrystal in a transmission electron microscope using the technique of electron diffraction tomography. This approach is described in details following a pedagogic route and a systematic comparison is made of this rather new method with other experimental methods of electron diffraction, and with the standard single crystal X-ray diffraction technique. Both transport and magnetic measurements, showed a transition at low temperature that may be correlated to Ru{sup 4+}/Ru{sup 5+} charge ordering. - Graphical abstract: Structure of Sr{sub 4}Ru{sub 6}ClO{sub 18}, determined using Precession Electron Diffraction data. - Highlights: • Structure of Sr{sub 4}Ru{sub 6}ClO{sub 18} was solved ab initio using precession electron diffraction. • This was done both on a nanometric sample and on a micrometric one. • Different type of experimental methods of electron diffraction are compared. • Single crystal X-ray diffraction was used to confirm the results. • Transport properties were characterized and show “exotic” behavior.

  5. Colloidal Suspensions of Rodlike Nanocrystals and Magnetic Spheres under an External Magnetic Stimulus: Experiment and Molecular Dynamics Simulation.

    PubMed

    May, Kathrin; Eremin, Alexey; Stannarius, Ralf; Peroukidis, Stavros D; Klapp, Sabine H L; Klein, Susanne

    2016-05-24

    Using experiments and molecular dynamics simulations, we explore magnetic field-induced phase transformations in suspensions of nonmagnetic rodlike and magnetic sphere-shaped particles. We experimentally demonstrate that an external uniform magnetic field causes the formation of small, stable clusters of magnetic particles that, in turn, induce and control the orientational order of the nonmagnetic subphase. Optical birefringence was studied as a function of the magnetic field and the volume fractions of each particle type. Steric transfer of the orientational order was investigated by molecular dynamics (MD) simulations; the results are in qualitative agreement with the experimental observations. By reproducing the general experimental trends, the MD simulation offers a cohesive bottom-up interpretation of the physical behavior of such systems, and it can also be regarded as a guide for further experimental research. PMID:27119202

  6. Calculating cellulose diffraction patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  7. Applied magnetic field design for the field reversed configuration compression heating experiment.

    PubMed

    Domonkos, M T; Amdahl, D; Camacho, J F; Coffey, S K; Degnan, J H; Delaney, R; Frese, M; Gale, D; Grabowski, T C; Gribble, R; Intrator, T P; McCullough, J; Montano, N; Robinson, P R; Wurden, G

    2013-04-01

    Detailed calculations of the formation, guide, and mirror applied magnetic fields in the FRC compression-heating experiment (FRCHX) were conducted using a commercially available generalized finite element solver, COMSOL Multiphysics(®). In FRCHX, an applied magnetic field forms, translates, and finally captures the FRC in the liner region sufficiently long to enable compression. Large single turn coils generate the fast magnetic fields necessary for FRC formation. Solenoidal coils produce the magnetic field for translation and capture of the FRC prior to liner implosion. Due to the limited FRC lifetime, liner implosion is initiated before the FRC is injected, and the magnetic flux that diffuses into the liner is compressed. Two-dimensional axisymmetric magnetohydrodynamic simulations using MACH2 were used to specify optimal magnetic field characteristics, and this paper describes the simulations conducted to design magnetic field coils and compression hardware for FRCHX. This paper presents the vacuum solution for the magnetic field. PMID:23635196

  8. Construction of a solenoid used on a magnetized plasma experiment

    NASA Astrophysics Data System (ADS)

    Klein, S. R.; Manuel, M. J.-E.; Pollock, B. B.; Gillespie, R. S.; Deininger, M.; Kuranz, C. C.; Keiter, P. A.; Drake, R. P.

    2014-11-01

    Creating magnetized jets in the laboratory is relevant to studying young stellar objects, but generating these types of plasmas within the laboratory setting has proven to be challenging. Here, we present the construction of a solenoid designed to produce an axial magnetic field with strengths in the gap of up to 5 T. This novel design was a compact 75 mm × 63 mm × 88 mm, allowing it to be placed in the Titan target chamber. It was robust, surviving over 50 discharges producing fields ≲ 5 T, reaching a peak magnetic field of 12.5 T.

  9. Cycloid spirals and cycloid cone transition in the HoMn6-xCrxGe6 (T, x) magnetic phase diagramm by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Schobinger-Papamantellos, P.; Rodríguez-Carvajal, J.; Buschow, K. H. J.

    2016-06-01

    The structures and magnetic properties of the antiferromagnetic hexagonal pseudo ternary compounds HoMn6-xCrxGe6 (x=1, 1.5 and 2) are studied by neutron diffraction in the temperature range 1.5-300 K. The substitution of nonmagnetic Cr for Mn greatly affects the magnetic properties of HoMn6Ge6 by reducing the ordering temperature from 466 K to 278 K, 205 K and 130 K for (x=0, 1, 1.5 and 2) respectively, increasing the c/a ratio, suppressing the high temperature (HT) commensurate phase with q2=(0, 0, 1/2) and changing the high temperature (LT) q1=(0, 0, q1z) skew spiral rotation plane. HoMn5CrGe6 and HoMn4Cr2Ge6 display in the entire magnetically ordered regime cycloid spiral structures with the wave vector: q=(0, 0, qz), qz≈0.18(3) r.l.u. and Φs≈64.8° turn angle. The Ho and Mn/Cr (001) layers have ferromagnetic arrangements coupled antiferromagnetically. The Ho moments in the z=0 layer are oriented in a direction opposite to the line bisecting the angle 2φMn≈2×28° of the Mn layers at z=±∼0.25. This triple unit changes orientation collectively in the direction of q within the (b, c) plane containing the wave vector. Above 50 K, the wave vector length increases linearly from 0.24 to 0.28(1) r.l.u. below TN. The HT HoMn4.5Cr1.5Ge6 cycloid spiral, is stable in the range Ttmagnetic satellites and the increase of characteristic nuclear intensities. The results are summarised in a (T, x) magnetic phase diagram.

  10. Description of the Large-Gap Magnetic Suspension System (LGMSS) ground based experiment

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.

    1991-01-01

    An overview of the Large Gap Magnetic Suspension System (LGMSS) ground-based experiment is provided. A description of the experiment, as originally defined, and the experiment objectives and potential applications of the technology resulting from the experiment are presented. Also, the results of two studies which were conducted to investigate the feasibility of implementing the experiment are presented and discussed. Finally, a description of the configuration which was selected for the experiment is described, and a summary of the paper is presented.

  11. Octupole Magnet For Soft X Ray Magnetic Dichroism Experiments: Design and Performance

    SciTech Connect

    Arenholz, Elke; Prestemon, Soren O.

    2004-05-12

    An octupole magnet endstation for soft x ray magnetic dichroism measurements has been developed at the Advanced Light Source. The system consists of an eight pole electromagnet that surrounds a small vacuum chamber. The magnet provides fields up to 0.9 T that can be applied in any direction relative to the incoming x ray beam. High precision magnetic circular and linear dichroism spectra can be obtained reversing the magnetic field for each photon energy in an energy scan. Moreover, the field dependence of all components of the magnetization vector can be studied in detail by choosing various angles of x ray incidence while keeping the relative orientation of magnetic field and sample fixed.

  12. Magnetic MAX phases from theory and experiments; a review.

    PubMed

    Ingason, A S; Dahlqvist, M; Rosen, J

    2016-11-01

    This review presents MAX phases (M is a transition metal, A an A-group element, X is C or N), known for their unique combination of ceramic/metallic properties, as a recently uncovered family of novel magnetic nanolaminates. The first created magnetic MAX phases were predicted through evaluation of phase stability using density functional theory, and subsequently synthesized as heteroepitaxial thin films. All magnetic MAX phases reported to date, in bulk or thin film form, are based on Cr and/or Mn, and they include (Cr,Mn)2AlC, (Cr,Mn)2GeC, (Cr,Mn)2GaC, (Mo,Mn)2GaC, (V,Mn)3GaC2, Cr2AlC, Cr2GeC and Mn2GaC. A variety of magnetic properties have been found, such as ferromagnetic response well above room temperature and structural changes linked to magnetic anisotropy. In this paper, theoretical as well as experimental work performed on these materials to date is critically reviewed, in terms of methods used, results acquired, and conclusions drawn. Open questions concerning magnetic characteristics are discussed, and an outlook focused on new materials, superstructures, property tailoring and further synthesis and characterization is presented. PMID:27602484

  13. Magnetic MAX phases from theory and experiments; a review

    NASA Astrophysics Data System (ADS)

    Ingason, A. S.; Dahlqvist, M.; Rosen, J.

    2016-11-01

    This review presents MAX phases (M is a transition metal, A an A-group element, X is C or N), known for their unique combination of ceramic/metallic properties, as a recently uncovered family of novel magnetic nanolaminates. The first created magnetic MAX phases were predicted through evaluation of phase stability using density functional theory, and subsequently synthesized as heteroepitaxial thin films. All magnetic MAX phases reported to date, in bulk or thin film form, are based on Cr and/or Mn, and they include (Cr,Mn)2AlC, (Cr,Mn)2GeC, (Cr,Mn)2GaC, (Mo,Mn)2GaC, (V,Mn)3GaC2, Cr2AlC, Cr2GeC and Mn2GaC. A variety of magnetic properties have been found, such as ferromagnetic response well above room temperature and structural changes linked to magnetic anisotropy. In this paper, theoretical as well as experimental work performed on these materials to date is critically reviewed, in terms of methods used, results acquired, and conclusions drawn. Open questions concerning magnetic characteristics are discussed, and an outlook focused on new materials, superstructures, property tailoring and further synthesis and characterization is presented.

  14. Experiment evaluation of speckle suppression efficiency of 2D quasi-spiral M-sequence-based diffractive optical element.

    PubMed

    Lapchuk, A; Pashkevich, G A; Prygun, O V; Yurlov, V; Borodin, Y; Kryuchyn, A; Korchovyi, A A; Shylo, S

    2015-10-01

    The quasi-spiral 2D diffractive optical element (DOE) based on M-sequence of length N=15 is designed and manufactured. The speckle suppression efficiency by the DOE rotation is measured. The speckle suppression coefficients of 10.5, 6, and 4 are obtained for green, violet, and red laser beams, respectively. The results of numerical simulation and experimental data show that the quasi-spiral binary DOE structure can be as effective in speckle reduction as a periodic 2D DOE structure. The numerical simulation and experimental results show that the speckle suppression efficiency of the 2D DOE structure decreases approximately twice at the boundaries of the visible range. It is shown that a replacement of this structure with the bilateral 1D DOE allows obtaining the maximum speckle suppression efficiency in the entire visible range of light. PMID:26479664

  15. An Analysis of the X-Ray Diffraction Signal for the (alpha) - (epsilon) Transition in Shock-Compressed Iron: Simulation and Experiment

    SciTech Connect

    Hawreliak, J; Colvin, J D; Kalantar, D H; Lorenzana, H E; Stolken, J S; Davies, H M; Germann, T C; Holian, B L; Kadau, K; Lomdahl, P S; Higginbotham, A; Rosolankova, K; Sheppard, J; Wark, J S

    2006-04-10

    Recent published work has shown that the phase change of shock compressed iron along the [001] direction does transform to the {epsilon} (HCP) phase similar to the case for static measurements. This article provides an indepth analysis of the experiment and NEMD simulations, using x-ray diffraction in both cases to study the crystal structure upon transition. Both simulation and experiment are consistent with a compression and shuffle mechanism responsible for the phase change from BCC to HCP. Also both show a polycrystalline structure upon the phase transition, due to the four degenerate directions the phase change can occur on, with grain sizes measured of 4nm in the NEMD simulations and {approx} 2nm in the experiment. And looking at the time scale of the transition the NEMD shows the transition from the compressed BCC to HCP is less then 1.2 ps where the experimental data places an upper limit on the transition of 80 ps.

  16. Parametric Powder Diffraction

    NASA Astrophysics Data System (ADS)

    David, William I. F.; Evans, John S. O.

    The rapidity with which powder diffraction data may be collected, not only at neutron and X-ray synchrotron facilities but also in the laboratory, means that the collection of a single diffraction pattern is now the exception rather than the rule. Many experiments involve the collection of hundreds and perhaps many thousands of datasets where a parameter such as temperature or pressure is varied or where time is the variable and life-cycle, synthesis or decomposition processes are monitored or three-dimensional space is scanned and the three-dimensional internal structure of an object is elucidated. In this paper, the origins of parametric diffraction are discussed and the techniques and challenges of parametric powder diffraction analysis are presented. The first parametric measurements were performed around 50 years ago with the development of a modified Guinier camera but it was the automation afforded by neutron diffraction combined with increases in computer speed and memory that established parametric diffraction on a strong footing initially at the ILL, Grenoble in France. The theoretical parameterisation of quantities such as lattice constants and atomic displacement parameters will be discussed and selected examples of parametric diffraction over the past 20 years will be reviewed that highlight the power of the technique.

  17. Tools and setups for experiments with AC and rotating magnetic fields

    NASA Astrophysics Data System (ADS)

    Ponikvar, D.

    2010-09-01

    A rotating magnetic field is the basis for the transformation of electrical energy to mechanical energy. School experiments on the rotating magnetic field are rare since they require the use of specially prepared mechanical setups and/or relatively large, three-phase power supplies to achieve strong magnetic fields. This paper proposes several experiments and describes setups and tools which are easy to obtain and work with. Free software is offered to generate the required signals by a personal computer. The experiments can be implemented in introductory physics courses on electromagnetism for undergraduates or specialized courses at high schools.

  18. Structural and composition studies on the mineral of newly formed dental enamel: a chemical, x-ray diffraction, and 31P and proton nuclear magnetic resonance study.

    PubMed

    Bonar, L C; Shimizu, M; Roberts, J E; Griffin, R G; Glimcher, M J

    1991-11-01

    The present report describes a study of the development and maturation of the mineral component of dental enamel. We prepared porcine enamel of different stages of maturation, from the very immature enamel of unerupted teeth, with a mineral content of 45%, to fully mature enamel, with a mineral content of approximately 99%. We fractionated the less mature enamel by density centrifugation and examined the enamel density fractions and unfractionated enamel by a variety of chemical and physical techniques, including conventional and radial distribution function x-ray diffraction analysis, conventional and Fourier transform infrared spectroscopy, 31P and 1H nuclear magnetic resonance spectroscopy, and chemical analysis. The three most immature preparations, from unerupted teeth, had mineral contents of 45, 67, and 91 and Ca/P molar ratios of 1.41, 1.44, and 1.47. Density distribution histograms of the three fractions show that the early maturation of dental enamel mineral is accompanied by an increase in tissue density, reflecting the increase in mineral content. The density distribution in each sample is relatively narrow, indicating that the maturation process occurs at a fairly homogeneous rate, with all enamel in an anatomically defined zone mineralizing to about the same extent. X-ray diffraction studies indicate that even the least mature, least mineralized of these immature samples is considerably more crystalline than the most mature bone mineral studied and that crystalline perfection of the enamel crystals crystals increases further with maturation. Both the a and c axes of the mineral unit cell expand significantly during early stages of maturation. Solid-state 31P nuclear magnetic resonance spectroscopy studies indicate that dental enamel contains a DCPD-like HPO4 component in an apatitic lattice, similar to the component previously observed in bone and some synthetic calcium phosphates. The proportion of this DCPD-like component decreases with maturation

  19. Localized magnetism on the surface of niobium: experiments and theory

    NASA Astrophysics Data System (ADS)

    Proslier, Thomas; Zasadzinski, John; Ciovati, Gianluigi; Pellin, Mike

    2011-03-01

    The presence of magnetic impurities in native niobium oxides have been confirmed by Point contact spectroscopy (PCT), SQUID magnetometry and Electron paramagnetic resonance (EPR). All niobium (Nb) samples displayed a small impurity contribution to the magnetic susceptibility at low temperatures which exhibited Curie-Weiss behavior, indicative of weakly coupled localized paramagnetic moments. By examining Nb samples with widely varying surface-to-volume ratios it was found that the impurity contribution is correlated with surface area. Tunneling measurements which use the native oxide layers as barriers exhibit a zero-bias conductance peak which splits in a magnetic field > 4 T , consistentwiththeAppelbaummodelforspinfliptunneling . ViewedtogethertheexperimentsstronglysuggestthatthenativeoxidesofNbareintrinsicallydefective , andconsistentlyexhibitlocalizedparamagneticmomentscausedbyoxygenvacanciesinNb 2 O 5 . Thecomputationofthesurfaceimpedance (R S) in presence of magnetic impurities in the Shiba approximation reveals the saturation at low temperature of Rs, suggesting that magnetic impurities are responsible for the so-called residual resistance. Work supported by DOE-HEP office, under contract No. DE-AC02-06CH11357.

  20. Quasi-static magnetic measurements to predict specific absorption rates in magnetic fluid hyperthermia experiments

    NASA Astrophysics Data System (ADS)

    Coral, D. F.; Mendoza Zélis, P.; de Sousa, M. E.; Muraca, D.; Lassalle, V.; Nicolás, P.; Ferreira, M. L.; Fernández van Raap, M. B.

    2014-01-01

    In this work, the issue on whether dynamic magnetic properties of polydispersed magnetic colloids modeled using physical magnitudes derived from quasi-static magnetic measurement can be extrapolated to analyze specific absorption rate data acquired at high amplitudes and frequencies of excitation fields is addressed. To this end, we have analyzed two colloids of magnetite nanoparticles coated with oleic acid and chitosan in water displaying, under a radiofrequency field, high and low specific heat power release. Both colloids are alike in terms of liquid carrier, surfactant and magnetic phase composition but differ on the nanoparticle structuring. The colloid displaying low specific dissipation consists of spaced magnetic nanoparticles of mean size around 4.8 nm inside a large chitosan particle of 52.5 nm. The one displaying high specific dissipation consists of clusters of magnetic nanoparticles of mean size around 9.7 nm inside a chitosan particle of 48.6 nm. The experimental evaluation of Néel and Brown relaxation times (˜10-10 s and 10-4 s, respectively) indicate that the nanoparticles in both colloids magnetically relax by Néel mechanism. The isothermal magnetization curves analysis for this mechanism show that the magnetic nanoparticles behave in the interacting superparamagnetic regime. The specific absorption rates were determined calorimetrically at 260 kHz and up to 52 kA/m and were well modeled within linear response theory using the anisotropy density energy retrieved from quasi-static magnetic measurement, validating their use to predict heating ability of a given polydispersed particle suspension. Our findings provide new insight in the validity of quasi-static magnetic characterization to analyze the high frequency behavior of polydispersed colloids within the framework of the linear response and Wohlfarth theories and indicate that dipolar interactions play a key role being their strength larger for the colloid displaying higher dissipation, i

  1. Backhopping in magnetic tunnel junctions: Micromagnetic approach and experiment

    NASA Astrophysics Data System (ADS)

    Frankowski, Marek; Skowroński, Witold; Czapkiewicz, Maciej; Stobiecki, Tomasz

    2015-01-01

    Micromagnetic simulations of Current Induced Magnetization Switching (CIMS) loops in CoFeB/MgO/CoFeB exchange-biased Magnetic Tunnel Junctions (MTJ) are discussed. Our model uses the Landau-Lifshitz-Gilbert equation with the Slonczewski's Spin-Transfer-Torque (STT) component. The current density for STT is calculated from the applied bias voltage and tunnel magnetoresistance which depends on the local magnetization vectors arrangement. We take into account the change in the anti-parallel state resistance with increasing bias voltage. Using such model we investigate influence of the interlayer exchange coupling, between free and reference layers across the barrier, on the backhopping effect in anti-parallel to parallel switching. We compare our simulated CIMS loops with the experimental data obtained from MTJs with different MgO barrier thicknesses.

  2. SINGLE CRYSTAL NEUTRON DIFFRACTION.

    SciTech Connect

    KOETZLE,T.F.

    2001-03-13

    Single-crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator-based spallation source. Single-crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Angstrom. For high-resolution studies requiring shorter wavelengths (ca. 0.3-0.8 Angstroms), a pulsed spallation source or a high-temperature moderator (a ''hot source'') at a reactor may be used. When complex structures with large unit-cell repeats are under investigation, as is the case in structural biology, a cryogenic-temperature moderator (a ''cold source'') may be employed to obtain longer neutron wavelengths (ca. 4-10 Angstroms). A single-crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean-square displacements, and relevant site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well, from the magnetic contribution to the Bragg intensities. This latter aspect falls beyond the scope of the present unit; for information on magnetic scattering of neutrons see Unit 14.3. Instruments for single-crystal diffraction (single-crystal diffractometers or SCDs) are generally available at the major neutron scattering center facilities. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts is included in an appendix accompanying this unit.

  3. Nonlinear dynamic behaviour of a rotor-foundation system coupled through passive magnetic bearings with magnetic anisotropy - Theory and experiment

    NASA Astrophysics Data System (ADS)

    Enemark, Søren; Santos, Ilmar F.

    2016-02-01

    In this work, the nonlinear dynamic behaviour of a vertical rigid rotor interacting with a flexible foundation by means of two passive magnetic bearings is quantified and evaluated. The quantification is based on theoretical and experimental investigation of the non-uniformity (anisotropy) of the magnetic field and the weak nonlinearity of the magnetic forces. Through mathematical modelling the nonlinear equations of motion are established for describing the shaft and bearing housing lateral dynamics coupled via the nonlinear and non-uniform magnetic forces. The equations of motion are solved in the frequency domain by the methods of Finite Difference and pseudo-arclength continuation. The theoretical findings are validated against experiments carried out using a dedicated test-rig and a special device for characterisation of the magnetic anisotropy. The characterisation of the magnetic anisotropy shows that it can be quantified as magnetic eccentricities having an amplitude and a phase, which result in linear and parametric excitation. The magnetic eccentricities are also determined using the steady-state response of the rotor-bearing system due to forcing from the magnetic anisotropies and several levels of mass imbalance. Discrepancies in the results from the two methods in terms of magnetic eccentricity magnitude are due to additional geometric eccentricities in the shaft. The steady-state system response shows clear nonlinear phenomena, e.g. bent resonance peaks, jump phenomena and nonlinear cross-coupling between the two orthogonal directions, especially during counter-phase motion between shaft and bearings. The clear nonlinear behaviour is facilitated by the lack of damping resulting in relatively large vibrations. The overall nonlinear dynamic behaviour is well captured by the theoretical model, thereby validating the modelling approach.

  4. FURTHER EXPERIENCE WITH SLC PERMANENT MAGNETIC (PM) MULTIPOLES

    SciTech Connect

    Spencer, James E.

    2003-05-29

    PM multipoles have been used in the SLAC damping rings (DR) and their injection and extraction lines since 1985. Due to upgrades of the DR vacuum chambers for higher currents in 1993, there was an opportunity to check some of these magnets[1]. Nothing more was done until a program of real-time radiation measurements was begun in the electron ring to determine causes, levels and effects of integrated gamma and neutron doses on the strengths and harmonic contents for NLC purposes. We discuss results of the latest magnetic measurements, radiation measurement program, semiconductor dosimeters and a few unexpected but interesting conclusions.

  5. Overview of the magnetic properties experiments onboard the two Mars Exploration Rovers, Spirit and Opportunity

    NASA Astrophysics Data System (ADS)

    Leer, K.; Bertelsen, P.; Goetz, W.; Hviid, S. F.; Madsen, D. E.; Madsen, M. B.; Olsen, M.; The, A.

    2007-05-01

    The two Mars Exploration Rovers, Spirit and Opportunity, are each equipped with seven magnets designed for three different purposes: 1. The Filter and Capture magnets collect dust from the atmosphere. The dust can be investigated by the science instruments on the robotic arm and imaged by the Panoramic Camera. Analyzes of the dust shows that the magnetic component in the martian dust is magnetite, hematite together with paramagnetic and possibly superparamagnetic compounds is responsible for the yellowish color of the dust and the presence of olivine shows that the dust is formed without any appreciable presence of water. 2. The ring shaped Sweep magnet is design to detect non-magnetic particles. The experiment has been negative so far, showing that all particles must be composite and magnetic. This experience has been used to design a new camera calibration target for the Phoenix 2007, the sweep effect significantly preventing the calibration target to get dusty during the mission. 3. The Rock Abrasion Tool magnets are design to support the Mössbauer measurements on rocks giving additional information about the magnetic minerals contained in rocks. We here report on the results from the rovers and the neer future prospective for magnetic properties experiments on Mars.

  6. Magnetically Actuated Propellant Orientation Experiment, Controlling Fluid Motion With Magnetic Fields in a Low-Gravity Environment

    NASA Technical Reports Server (NTRS)

    Martin, J. J.; Holt, J. B.

    2000-01-01

    This report details the results of a series of fluid motion experiments to investigate the use of magnets to orient fluids in a low-gravity environment. The fluid of interest for this project was liquid oxygen (LO2) since it exhibits a paramagnetic behavior (is attracted to magnetic fields). However, due to safety and handling concerns, a water-based ferromagnetic mixture (produced by Ferrofluidics Corporation) was selected to simplify procedures. Three ferromagnetic fluid mixture strengths and a nonmagnetic water baseline were tested using three different initial fluid positions with respect to the magnet. Experiment accelerometer data were used with a modified computational fluid dynamics code termed CFX-4 (by AEA Technologies) to predict fluid motion. These predictions compared favorably with experiment video data, verifying the code's ability to predict fluid motion with and without magnetic influences. Additional predictions were generated for LO2 with the same test conditions and geometries used in the testing. Test hardware consisted of a cylindrical Plexiglas tank (6-in. bore with 10-in. length), a 6,000-G rare Earth magnet (10-in. ring), three-axis accelerometer package, and a video recorder system. All tests were conducted aboard the NASA Reduced-Gravity Workshop, a KC-135A aircraft.

  7. Magnetic Control of Solutal Buoyancy-driven Convection. Part 1; Theory and Experiments

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Leslie, F. W.

    2003-01-01

    Experiments on solutal convection in a paramagnetic fluid were conducted in a strong magnetic field gradient using a dilute solution of Manganese Chloride. The observed flows indicate that the magnetic field can completely counter the settling effects of gravity locally and are consistent with the theoretical predictions presented.

  8. Using Experiment and Computer Modeling to Determine the Off-Axis Magnetic Field of a Solenoid

    ERIC Educational Resources Information Center

    Lietor-Santos, Juan Jose

    2014-01-01

    The study of the ideal solenoid is a common topic among introductory-based physics textbooks and a typical current arrangement in laboratory hands-on experiences where the magnetic field inside a solenoid is determined at different currents and at different distances from its center using a magnetic probe. It additionally provides a very simple…

  9. Biological Effects of Static Magnetic Fields: Ideal Experiments for Introductory Courses

    ERIC Educational Resources Information Center

    Kendler, Barry S.; Grove, Patricia A.

    2005-01-01

    A serendipitous finding involving static magnetic fields can be used to design experiments suitable for both science and nonscience majors. It has been reported that organisms respond differently to high-gauss magnetic fields generated by north poles than they do to those generated by south poles. Experimental tests of this hypothesis are ideal…

  10. Magnetic field dependent neutron powder diffraction studies of Ru{sub 0.9}Sr{sub 2}YCu{sub 2.1}O{sub 7.9}

    SciTech Connect

    Nigam, R.; Pan, A. V.; Dou, S. X.; Kennedy, S. J.; Studer, A. J.; Stuesser, N.

    2010-05-15

    Temperature and magnetic field dependent neutron diffraction has been used to study the magnetic order in Ru{sub 0.9}Sr{sub 2}YCu{sub 2.1}O{sub 7.9}. The appearance of (1/2, 1/2, 1/2), (1/2, 1/2, 3/2), and (1/2, 1/2, 5/2) peaks below T{sub M}=140 K manifests the antiferromagnetic order. Neutron diffraction patterns measured in applied magnetic fields from 0 to 6 T show the destruction of the antiferromagnetic order with increasing field. There is no evidence of spontaneous or field-induced long range ferromagnetic order. This latter result contradicts the vast majority of other experimental observations for this system.

  11. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    DOE PAGES

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compressionmore » and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.« less

  12. Magnetic design calculation and FRC formation modeling for the field reversed experiment liner

    SciTech Connect

    Dorf, L. A.; Intrator, T. P.; Renneke, R.; Hsu, S. C.; Wurden, G. A.; Awe, T.; Siemon, R.; Semenov, V. E.

    2008-10-01

    Integrated magnetic modeling and design are important to meet the requirements for (1) formation, (2) translation, and (3) compression of a field reversed configuration (FRC) for magnetized target fusion. Off-the-shelf solutions do not exist for many generic design issues. A predictive capability for time-dependent magnetic diffusion in realistically complicated geometry is essential in designing the experiment. An eddy-current code was developed and used to compute the mutual inductances between driven magnetic coils and passive magnetic shields (flux excluder plates) to calculate the self-consistent axisymmetric magnetic fields during the first two stages. The plasma in the formation stage was modeled as an immobile solid cylinder with selectable constant resistivity and magnetic flux that was free to readjust itself. It was concluded that (1) use of experimentally obtained anomalously large plasma resistivity in magnetic diffusion simulations is sufficient to predict magnetic reconnection and FRC formation, (2) comparison of predicted and experimentally observed timescales for FRC Ohmic decay shows good agreement, and (3) for the typical range of resistivities, the magnetic null radius decay rate scales linearly with resistivity. The last result can be used to predict the rate of change in magnetic flux outside of the separatrix (equal to the back-emf loop voltage), and thus estimate a minimum {theta}-coil loop voltage required to form an FRC.

  13. Vacuum magnetic linear birefringence using pulsed fields: status of the BMV experiment

    NASA Astrophysics Data System (ADS)

    Cadène, Agathe; Berceau, Paul; Fouché, Mathilde; Battesti, Rémy; Rizzo, Carlo

    2014-01-01

    We present the current status of the BMV experiment. Our apparatus is based on an up-to-date resonant optical cavity coupled to a transverse magnetic field. We detail our data acquisition and analysis procedure which takes into account the symmetry properties of the raw data with respect to the orientation of the magnetic field and the sign of the cavity birefringence. The measurement result of the vacuum magnetic linear birefringence k CM presented in this paper was obtained with about 200 magnetic pulses and a maximum field of 6.5 T, giving a noise floor of about 8 × 10-21 T-2 at 3 σ confidence level.

  14. Magnetic shielding in a low temperature torsion pendulum experiment. [superconducting cylinders for attenuation earth field

    NASA Technical Reports Server (NTRS)

    Phillips, P. R.

    1979-01-01

    A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.

  15. Magnetic Field R&D for the neutron EDM experiment at TRIUMF

    NASA Astrophysics Data System (ADS)

    Mammei, Russell R.

    2014-09-01

    The neutron EDM experiment at TRIUMF aims to constrain the EDM with a precision of 1 ×10-27 e-cm by 2018. The experiment will use a spallation ultracold neutron (UCN) source employing superfluid helium coupled to a room-temperature EDM apparatus. In the previous best experiment, conducted at ILL, effects related to magnetic field homogeneity and instability were found to dominate the systematic error. This presentation will cover our R&D efforts on passive and active magnetic shielding, magnetic field generation within shielded volumes, and precision magnetometry. The neutron EDM experiment at TRIUMF aims to constrain the EDM with a precision of 1 ×10-27 e-cm by 2018. The experiment will use a spallation ultracold neutron (UCN) source employing superfluid helium coupled to a room-temperature EDM apparatus. In the previous best experiment, conducted at ILL, effects related to magnetic field homogeneity and instability were found to dominate the systematic error. This presentation will cover our R&D efforts on passive and active magnetic shielding, magnetic field generation within shielded volumes, and precision magnetometry. Supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, and the Canada Research Chairs program.

  16. [Application of variable magnetic fields in medicine--15 years experience].

    PubMed

    Sieroń, Aleksander; Cieślar, Grzegorz

    2003-01-01

    The results of 15-year own experimental and clinical research on application of variable magnetic fields in medicine were presented. In experimental studies analgesic effect (related to endogenous opioid system and nitrogen oxide activity) and regenerative effect of variable magnetic fields with therapeutical parameters was observed. The influence of this fields on enzymatic and hormonal activity, free oxygen radicals, carbohydrates, protein and lipid metabolism, dielectric and rheological properties of blood as well as behavioural reactions and activity of central dopamine receptor in experimental animals was proved. In clinical studies high therapeutic efficacy of magnetotherapy and magnetostimulation in the treatment of osteoarthrosis, abnormal ossification, osteoporosis, nasosinusitis, multiple sclerosis, Parkinson's disease, spastic paresis, diabetic polyneuropathy and retinopathy, vegetative neurosis, peptic ulcers, colon irritable and trophic ulcers was confirmed. PMID:15049208

  17. Magnetic flux-trapping experiment with a moving conductor.

    PubMed

    Hovorka, J

    1969-11-14

    An aluminum conductor moving into and out of a magnetic field of 75 gauss traps within itself for varying lengths of time a detectable fraction of the encountered flux, which subsequently decays. A time constant of about 0.005 second, which is the order of magnitude predicted by classical electrodynamics, is measured. The result is of interest in connection with the "frozen-in field" concept of Babcock's sunspot model.

  18. Pioneer 10 and 11 (Jupiter and Saturn) magnetic field experiments

    NASA Technical Reports Server (NTRS)

    Jones, D. E.

    1986-01-01

    Magnet field data obtained by the vector helium magnetometer (VHM) during the encounters of Jupiter (Pioneer 10 and 11) and Saturn (Pioneer 11) was analyzed and interpreted. The puzzling characteristics of the Jovian and Saturnian magnetospheric magnetic fields were studied. An apparent substorm (including thinning of the dayside tail current sheet) was observed at Jupiter, as well as evidence suggesting that at the magnetopause the cusp is at an abnormally low latitude. The characteristics of Saturn's ring current as observed by Pioneer 11 were dramatically different from those suggested by the Voyager observations. Most importantly, very strong perturbations in the azimuthal ring current magnetic field suggest that the plane of the ring was not in the dipole equatorial plane, being tilted 5 to 10 deg. relative to the dipole and undergoing significant changes during the encounter. When these changing currents were corrected for, an improved planetary field determination was obtained. In addition, the ring and azimuthal currents at Saturn displayed significantly different time dependences.

  19. Novel Material Designed to Achieve Greater Tunability of Magnetic Dynamo Experiments

    NASA Astrophysics Data System (ADS)

    Casara, J. G.; Brown, E.

    2013-12-01

    We propose to use a novel material for dynamo experiments, creating suspensions of magnetic particles in liquid metals. These suspensions combine the conductive nature of liquid metals with the magnetic permeabilities of the particles, allowing much higher magnetic Reynolds numbers than previous liquid-metal experiments. Additionally, by adjusting the packing fraction φ of non-magnetic or magnetic particles in suspension, we can tune the viscosity and permeability respectively, thus achieving independent control of Reynolds and magnetic Reynolds numbers over a wide range of parameter space. We will report rheology measurements showing that liquid metal suspensions of 10μm diameter iron powders in a eutectic mixture of gallium and indium exhibit Newtonian viscosity with the expected increase in viscosity with φ up to φ = 0.22. Preliminary investigation into the magnetic properties of these suspensions has suggested that magnetic permeabilities are proportional to the packing fraction and inherent permeability of the suspended particles. These results confirm that the resulting Reynolds and magnetic Reynolds numbers will be highly tunable and straightforward to predict based on the proportions and properties of the suspension materials. The flow curve for suspensions of iron powder in eutectic gallium and indium exhibit Newtonian-like behavior for packing fractions φ below φ = 0.22. The viscosities of suspensions of iron powder in a eutectic mixture of gallium and indium follow a Krieger-Dougherty curve, providing more evidence that the material behaves in a Newtonian-like manner.

  20. Shimming of a Magnet for Calibration of NMR Probes for the Muon g-2 Experiment

    NASA Astrophysics Data System (ADS)

    Bielajew, Rachel

    2013-10-01

    The Muon g-2 Experiment at Fermilab aims to measure the anomalous magnetic moment aμ ≡ (g-2)/2 of the muon to the precision of 0.14 parts per million. This experimental value of aμ can then be compared to the similarly precise theoretical predictions of the Standard Model in order to test the completeness of the model. The value of aμ is extracted from muons precessing in a magnetic field. The magnetic field will be measured with a set of 400 Nuclear Magnetic Resonance (NMR) probes, which have the ability to measure the field to a precision of tens of parts per billion. Before the Muon g-2 Experiment can take place, new NMR probes must be designed, built, and tested using a 1.45 Tesla test magnet at the University of Washington Center for Experimental Nuclear Physics and Astrophysics (CENPA). In order to achieve a significant signal from NMR probes, the magnetic field in which the probes are immersed must be extremely uniform. The existing magnet at CENPA has an approximately linear gradient in magnetic field of about 1 Gauss per centimeter in the smoothest direction. A pair of adjacent square Helmholtz coils was designed and built to create a linear gradient in order to cancel the existing gradient. The length of the NMR signals improved with the implementation of the coils. The results of the addition of the coils to the magnet on the signals from the NMR probes will be presented.

  1. Magnetic behavior of the giant Heisenberg molecular magnet Mo_72Fe_30: Classical theory and experiment

    NASA Astrophysics Data System (ADS)

    Luban, Marshall; Modler, Robert; Axenovich, Maria; Canfield, Paul; Bud'Ko, Sergey; Schröder, Christian; Schnack, Jürgen; Müller, Achim; Kögerler, Paul; Harrison, Neil

    2001-03-01

    The Keplerate species Mo_72Fe_30 containing 30 high-spin Fe^3+ ions, is by far the largest paramagnetic molecule synthesized to date, and it serves as an effective building block and prototype for a new class of diverse molybdenum-oxygen based compounds. These substances are of importance for identifying the most pertinent criteria for the passage from microscopic to macroscopic magnetism, and for their potential as molecular-based electronic and magnetic devices. We report excellent agreement, from room temperature down to 0.1 K, and for magnetic fields up to 60 Tesla between our theoretical results based on the classical Heisenberg model and our measurements of its magnetic properties.

  2. Magnetic field and shock effects and remanent magnetization in a hypervelocity impact experiment. [lunar surface magnetization simulation

    NASA Technical Reports Server (NTRS)

    Srnka, L. J.; Martelli, G.; Newton, G.; Cisowski, S. M.; Fuller, M. D.; Schaal, R. B.

    1979-01-01

    The impact of aluminum projectiles onto high-alumina terrestrial basalt blocks at 13-15 km/s in the presence of a variable magnetic field is studied. Plasma production but not field production was detected, and characteristics of the remanence and the shocked basalt are reported. Mineralogical data suggest that the magnetization acquired in the material near the craters is shock remanence. The experimental results might indicate that shock effects or possibly thermoremanence in ejecta fragments, may be responsible for part of the magnetization of the lunar surface.

  3. "School Adopts an Experiment": The Magnetic Levitation of Superconductors

    ERIC Educational Resources Information Center

    Gallitto, Aurelio Agliolo

    2010-01-01

    The event "School adopts an experiment" is an event targeted at high schools and secondary schools. It is based on a tight and direct collaboration between researchers and school students and teachers. Several schools were involved in the event by "adopting" an experiment in physics research laboratories. Groups of selected students were first…

  4. 'School adopts an experiment': the magnetic levitation of superconductors

    NASA Astrophysics Data System (ADS)

    Agliolo Gallitto, Aurelio

    2010-09-01

    The event 'School adopts an experiment' is an event targeted at high schools and secondary schools. It is based on a tight and direct collaboration between researchers and school students and teachers. Several schools were involved in the event by 'adopting' an experiment in physics research laboratories. Groups of selected students were first trained by university researchers, then they demonstrated the experiments to other students and teachers during the event. Students who adopted an experiment acquired knowledge of the subjects connected with the experiment in a most impressive way compared with the usual didactics at school. Further positive points were: (i) to establish a close and direct collaboration between university researchers and high-school students and teachers; (ii) to give school students the opportunity to visit physics research laboratories.

  5. Using Magnetic Field Gradients to Simulate Variable Gravity in Fluids and Materials Experiments

    NASA Technical Reports Server (NTRS)

    Ramachandran, Narayanan

    2006-01-01

    Fluid flow due to a gravitational field is caused by sedimentation, thermal buoyancy, or solutal buoyancy induced convection. During crystal growth, for example, these flows are undesirable and can lead to crystal imperfections. While crystallization in microgravity can approach diffusion limited growth conditions (no convection), terrestrially strong magnetic fields can be used to control fluid flow and sedimentation effects. In this work, a theory is presented on the stability of solutal convection of a magnetized fluid(weak1y paramagnetic) in the presence of a magnetic field. The requirements for stability are developed and compared to experiments performed within the bore of a superconducting magnet. The theoretical predictions are in good agreement with the experiments. Extension of the technique can also be applied to study artificial gravity requirements for long duration exploration missions. Discussion of this application with preliminary experiments and application of the technique to crystal growth will be provided.

  6. ALICE—An advanced reflectometer for static and dynamic experiments in magnetism at synchrotron radiation facilities

    NASA Astrophysics Data System (ADS)

    Abrudan, R.; Brüssing, F.; Salikhov, R.; Meermann, J.; Radu, I.; Ryll, H.; Radu, F.; Zabel, H.

    2015-06-01

    We report on significant developments of a high vacuum reflectometer (diffractometer) and spectrometer for soft x-ray synchrotron experiments which allows conducting a wide range of static and dynamic experiments. Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. The versatility of the instrument was testified by a series of pilot experiments. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. We demonstrate here the capabilities of the system to host a variety of experiments, featuring ALICE as one of the most versatile and demanded instruments at the Helmholtz Center in Berlin-BESSY II synchrotron center in Berlin, Germany.

  7. Results on hard diffractive production

    SciTech Connect

    Goulianos, K.

    1995-07-01

    The results of experiments at hadron colliders probing the structure of the pomeron through hard diffraction are reviewed. Some results on deep inelastic diffractive scattering obtained a HERA are also discussed and placed in perspective. By using a properly normalized pomeron flux factor in single diffraction dissociation, as dictated by unitarity, the pomeron emerges as a combination of valence quark and gluon color singlets in a ratio suggested by asymptopia.

  8. Magnetic acceleration of aluminum foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Martinez, David; Plechaty, Christopher; Stein, Sandra; Presura, Radu

    2010-06-01

    Scaled experiments studying the interaction of shock waves with inhomogeneous background media are essential for understanding many astrophysical phenomena, since they can be used to test analytical theories and simulation codes. We are currently developing such experiments at the Nevada Terawatt Facility. We are using a pulsed power generator (1 MA peak current) to accelerate thin aluminum flyer plates. By impacting these foils on low-density foam targets, we will be able to carry out scaled experiments. We have demonstrated velocities of up to 8 km/s for 50 μm thick aluminum flyers, and are planning to further increase the flyer velocities. We have also carried out first impact tests with transparent polycarbonate targets. Several improvements for our setup are currently in planning, and these improvements will enable us to design scaled experiments for our facility.

  9. SU-E-J-233: A Facility for Radiobiological Experiments in a Large Magnetic Field

    SciTech Connect

    Carlone, M; Heaton, R; Keller, H; Wouters, B; Jaffray, D

    2014-06-01

    Purpose: There is considerable interest in developing medical linear accelerators with integrated image guidance by MRI. Less work has been done on the fundamental biology of cell survival in the presence of a strong magnetic field. The purpose of this work is to describe an experimental system capable of measuring cell survival response in the types of MRI-linac systems currently under development. Methods: We have integrated a cobalt irradiator with a solenoid magnet. The solenoid magnet has inner diameter of 10 cm. To enable measurement of the biological effects as a function of depth, we are utilizing the sliced gel technique, in which cells are embedded and fixed within a gelatin matrix. Irradiated cells at defined positions (sub mm resolution) can subsequently be recovered and assessed for cell survival or other biological effects. Results: The magnetic field profile in the solenoid has a peak magnetic field 36 cm below the top edge of the magnet bore and can be placed at and SAD of 100 cm. At a solenoid current of 35 A, the peak magnetic field is 0.25 T. The dose rate of the cobalt irradiator is 16 cGy/min at 100 cm SAD. EBT3 film was used to demonstrate the system functionality. It was irradiated at 1 cm depth at 100 cm SSD with a 4×4 field to 1.5 Gy in a 0.25 T magnetic field. The dose profile was similar between this film and the control exposure without magnetic field. Conclusion: Integrating a cobalt irradiator with a high field magnet is demonstrated. The magnetic field at the cobalt defining head was minimal and did not interfere with the functioning of this unit. Cell survival experiments can be reproduced exactly in the presence or absence of a magnetic field since a resistive magnet is used.

  10. Characteristics of detrital magnetization from redeposition experiments of different natural sediments

    NASA Astrophysics Data System (ADS)

    Spassov, S.; Valet, J. M.

    2011-12-01

    Several series of experiments have been carried out with carbonate-rich and clay-rich sediments re-deposited in plastic cubes or in 1 meter long cylindrical tubes with the aim of investigating the sensitivity of detrital magnetization to various environmental and physical parameters. In contrast to previous studies, we did not observe any difference in the detrital magnetization acquired with or without salt for both kinds of sediments. Taking advantage of a gelatin that fixes the position of the particles in suspension, we have been able to measure the magnetization of suspended sediments within water filled columns and thus to test the degree of alignment of the magnetic grains. The magnetization of the clayish sediments was not far from saturation but was considerably reduced after deflocculation because the large size flocs that favored the alignment of the magnetic grains were destroyed by the deflocculant. Similarly, the big flocs found at the bottom of the tubes also reveal a strong magnetic alignment. In contrast, the low magnetization of the carbonated-rich sediments with small size flocs yielded accurate and well-grouped directions of magnetization that were not sensitive to deflocculation. Only a fraction of magnetic grains has been mechanically oriented by the field in this case because of the weak net magnetic moments of the grains embedded within small flocs. The depositional remanent magnetization (DRM) has been constrained by re-depositions in plastic cubes performed without gelatin in presence of different field intensities. The DRM intensity of the carbonated sediments has been found to be linearly related to field strength, hence attesting their suitability for studies of relative paleointensity. Tests performed with mud picked up from several stratigraphic levels in different marine cores failed to reveal a significant influence of the carbonate content on detrital magnetization, and thus put forward the relatively minor role of lithological

  11. Femtosecond Electron Diffraction and Shadow Imaging

    NASA Astrophysics Data System (ADS)

    McPherson, David

    2010-03-01

    Using femtosecond electron pulses as an imaging tool, we can probe ultrafast dynamics by taking snapshots at different time delays. By using femtosecond electron diffraction (FED), we can examine structural dynamics at the atomic level in real time, and study the structure-function correlation. Additionally, femtosecond electron shadow imaging (FESI) can explore the dynamics of laser induced plasmas off the surfaces of conductors, semiconductors, and insulators. Project as part of a Research Experience for Undergraduates program funded by the National High Magnetic Field Laboratory, Florida State University and the National Science Foundation under supervision of Jianming Cao, PhD., Florida State University.

  12. Structural Isomer Identification via NMR: A Nuclear Magnetic Resonance Experiment for Organic, Analytical, or Physical Chemistry.

    ERIC Educational Resources Information Center

    Szafran, Zvi

    1985-01-01

    Background information, procedures used, and typical results obtained are provided for an experiment that examines the ability of nuclear magnetic resonance (NMR) to distinguish between structural isomers via resonance multiplicities and chemical shifts. Reasons for incorporating the experiment into organic, analytical, or physical chemistry…

  13. Magnetic field reversals: the geodynamo, laboratory experiments and models (Lewis Fry Richardson Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Fauve, S.

    2009-04-01

    I will first compare reversals of Earth's magnetic field known from palaeomagnetic data to the ones observed in a laboratory experiment for the magnetic field generated by a turbulent flow of liquid sodium (VKS experiment). Despite major differences between the flow in Earth's core and in the experiment, both systems display reversals that share a lot of similar properties. I will understand them using a simple model in the framework of low dynamical system theory. Finally, I will discuss what can be learnt from numerical simulations.

  14. RAT magnet experiment on the Mars Exploration Rovers: Spirit and Opportunity beyond sol 500

    NASA Astrophysics Data System (ADS)

    Leer, Kristoffer; Goetz, Walter; Chan, Marjorie A.; Gorevan, Steven; Hansen, Mikkel Fougt; Jensen, Christian Lundmand; Kletetschka, Gunther; Kusack, Alastair; Madsen, Morten Bo

    2011-04-01

    The Rock Abrasion Tool (RAT) magnet experiment on the Mars Exploration Rovers was designed to collect dust from rocks ground by the RAT of the two rovers on the surface of Mars. The dust collected on the magnets is now a mixture of dust from many grindings. Here the new data from the experiment are presented. The findings from Mars are furthermore compared to simulation experiments performed on Earth. New experiments with analog rocks that mainly contain hematite indicate the likely presence of a stronger magnetic phase besides hematite in the outcrop rock formations found on Meridiani Planum, a phase which was hitherto not detected by other measurements (such as Mössbauer) on these rocks.

  15. Simulating the magnetized liner inertial fusion plasma confinement with smaller-scale experiments

    SciTech Connect

    Ryutov, D. D.; Cuneo, M. E.; Herrmann, M. C.; Sinars, D. B.; Slutz, S. A.

    2012-06-15

    The recently proposed magnetized liner inertial fusion approach to a Z-pinch driven fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010)] is based on the use of an axial magnetic field to provide plasma thermal insulation from the walls of the imploding liner. The characteristic plasma transport regimes in the proposed approach cover parameter domains that have not been studied yet in either magnetic confinement or inertial confinement experiments. In this article, an analysis is presented of the scalability of the key physical processes that determine the plasma confinement. The dimensionless scaling parameters are identified and conclusion is drawn that the plasma behavior in scaled-down experiments can correctly represent the full-scale plasma, provided these parameters are approximately the same in two systems. This observation is important in that smaller-scale experiments typically have better diagnostic access and more experiments per year are possible.

  16. Dynamic field-frequency lock for tracking magnetic field fluctuations in electron spin resonance experiments

    NASA Astrophysics Data System (ADS)

    Asfaw, Abraham; Tyryshkin, Alexei; Lyon, Stephen

    Global magnetic field fluctuations present significant challenges to pulsed electron spin resonance experiments on systems with long spin coherence times. We will discuss results from experiments in which we follow instantaneous changes in magnetic field by locking to the free induction decay of a proton NMR signal using a phase-locked loop. We extend conventional field-frequency locking techniques used in NMR to follow slow magnetic field drifts by using a modified Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence in which the phase of the pi-pulses follows the phase of the proton spins at all times. Hence, we retain the ability of the CPMG pulse sequence to refocus local magnetic field inhomogeneities without refocusing global magnetic field fluctuations. In contrast with conventional field-frequency locking techniques, our experiments demonstrate the potential of this method to dynamically track global magnetic field fluctuations on timescales of about 2 seconds and with rates faster than a kHz. This frequency range covers the dominant noise frequencies in our electron spin resonance experiments as previously reported.

  17. Magnetic induction and diffusion mechanisms in a liquid sodium spherical Couette experiment

    NASA Astrophysics Data System (ADS)

    Cabanes, Simon; Schaeffer, Nathanaël; Nataf, Henri-Claude

    2014-10-01

    We present a reconstruction of the mean axisymmetric azimuthal and meridional flows in the Derviche Tourneur Sodium installation in Grenoble liquid sodium experiment. The experimental device sets a spherical Couette flow enclosed between two concentric spherical shells where the inner sphere holds a strong dipolar magnet, which acts as a magnetic propeller when rotated. Measurements of the mean velocity, mean induced magnetic field, and mean electric potentials have been acquired inside and outside the fluid for an inner sphere rotation rate of 9 Hz (Rm≃28 ). Using the induction equation to relate all measured quantities to the mean flow, we develop a nonlinear least-squares inversion procedure to reconstruct a fully coherent solution of the mean velocity field. We also include in our inversion the response of the fluid layer to the nonaxisymmetric time-dependent magnetic field that results from deviations of the imposed magnetic field from an axial dipole. The mean azimuthal velocity field we obtain shows superrotation in an inner region close to the inner sphere where the Lorentz force dominates, which contrasts with an outer geostrophic region governed by the Coriolis force, but where the magnetic torque remains the driver. The meridional circulation is strongly hindered by the presence of both the Lorentz and the Coriolis forces. Nevertheless, it contributes to a significant part of the induced magnetic energy. Our approach sets the scene for evaluating the contribution of velocity and magnetic fluctuations to the mean magnetic field, a key question for dynamo mechanisms.

  18. Interventional Magnetic Resonance Imaging Clinic: The Emory University Experience.

    PubMed

    Nour, Sherif G; Powell, Tracy E; Eberhardt, Joy; Bowen, Michael A; Pennington, Greg; Meltzer, Carolyn Cidis

    2015-11-01

    In this article, we share our experience in establishing a clinic-based practice for MR imaging-guided interventions. Clinic resources and operational logistics are described and our institutional cost analysis for supporting the clinic activity is provided. We highlight the overall value of the clinic model in transitioning the field of interventional MR imaging from the "proof-of-concept" to the "working model" era and engage in a detailed discussion of our experience with the positive impact of the clinic on streamlining the procedural workflow, increasing awareness of the technology, expanding referral bases, and boosting the satisfaction of both patients and referring services. PMID:26499284

  19. A compact electron gun for time-resolved electron diffraction

    SciTech Connect

    Robinson, Matthew S.; Lane, Paul D.; Wann, Derek A.

    2015-01-15

    A novel compact time-resolved electron diffractometer has been built with the primary goal of studying the ultrafast molecular dynamics of photoexcited gas-phase molecules. Here, we discuss the design of the electron gun, which is triggered by a Ti:Sapphire laser, before detailing a series of calibration experiments relating to the electron-beam properties. As a further test of the apparatus, initial diffraction patterns have been collected for thin, polycrystalline platinum samples, which have been shown to match theoretical patterns. The data collected demonstrate the focusing effects of the magnetic lens on the electron beam, and how this relates to the spatial resolution of the diffraction pattern.

  20. Repulsive magnetic levitation-based ocean wave energy harvester with variable resonance: Modeling, simulation and experiment

    NASA Astrophysics Data System (ADS)

    Masoumi, Masoud; Wang, Ya

    2016-10-01

    This paper investigates a magnetic levitation characteristic used in a vibration based energy harvester, called repulsive magnetic scavenger (RMS). The RMS is capable of harvesting ocean wave energy with a unique repelling permanent magnet array, which provides a stronger and more uniform magnetic field, compared to its attracting magnetic counterparts. The levitating magnets are stacked together around a threaded rod so that the same pole is facing each other. Two fixed magnets placed with one at each end of the RMS provides a collocated harvesting and braking mechanism in the face of high amplitude vibrations. Magnets in the levitated magnet stack are separated by pole pieces which are made of metals to intensify the magnetic field strength. The effect of the thickness and the use of different materials with different permeability for pole pieces is also studied to obtain an optimal energy harvesting efficiency. Moreover, the procedure to find the restoring force applied to the levitating magnet stack is demonstrated. Then, the Duffing vibration equation of the harvester is solved and the frequency response function is calculated for various force amplitudes and electrical damping so as to investigate the effect of these parameters on the response of the system. Furthermore, the effect of the maximum displacement of the moving magnet stack on the natural frequency of the device is studied. And finally, Faraday's law is employed to estimate the output voltage and power of the system under the specified input excitation force. Experiments show that the output emf voltage of the manufactured prototype reaches up to 42 V for an excitation force with the frequency of 9 Hz and the maximum amplitude of 3.4 g.

  1. Computer Simulation of Diffraction Patterns.

    ERIC Educational Resources Information Center

    Dodd, N. A.

    1983-01-01

    Describes an Apple computer program (listing available from author) which simulates Fraunhofer and Fresnel diffraction using vector addition techniques (vector chaining) and allows user to experiment with different shaped multiple apertures. Graphics output include vector resultants, phase difference, diffraction patterns, and the Cornu spiral…

  2. Color Perception with Diffraction Gratings.

    ERIC Educational Resources Information Center

    Kruglak, Haym; Campbell, Don

    1983-01-01

    Describes an experiment enabling students to apply concept of diffraction, determine limits of their color perception, learn how to measure wavelength with a simple apparatus, observe continuous and line spectra, and associate colors with corresponding wavelengths. The homemade diffraction-grating spectrometer used is easily constructed. (JN)

  3. Global distribution of crustal magnetization discovered by the mars global surveyor MAG/ER experiment

    PubMed

    Acuna; Connerney; Ness; Lin; Mitchell; Carlson; McFadden; Anderson; Reme; Mazelle; Vignes; Wasilewski; Cloutier

    1999-04-30

    Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between approximately 100 and 200 kilometers. Magnetic field sources of multiple scales, strength, and geometry were observed. There is a correlation between the location of the sources and the ancient cratered terrain of the martian highlands. The absence of crustal magnetism near large impact basins such as Hellas and Argyre implies cessation of internal dynamo action during the early Naochian epoch ( approximately 4 billion years ago). Sources with equivalent magnetic moments as large as 1.3 x 10(17) ampere-meter2 in the Terra Sirenum region contribute to the development of an asymmetrical, time-variable obstacle to solar wind flow around Mars.

  4. Global distribution of crustal magnetization discovered by the mars global surveyor MAG/ER experiment

    PubMed

    Acuna; Connerney; Ness; Lin; Mitchell; Carlson; McFadden; Anderson; Reme; Mazelle; Vignes; Wasilewski; Cloutier

    1999-04-30

    Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between approximately 100 and 200 kilometers. Magnetic field sources of multiple scales, strength, and geometry were observed. There is a correlation between the location of the sources and the ancient cratered terrain of the martian highlands. The absence of crustal magnetism near large impact basins such as Hellas and Argyre implies cessation of internal dynamo action during the early Naochian epoch ( approximately 4 billion years ago). Sources with equivalent magnetic moments as large as 1.3 x 10(17) ampere-meter2 in the Terra Sirenum region contribute to the development of an asymmetrical, time-variable obstacle to solar wind flow around Mars. PMID:10221908

  5. Microstructural investigation of LixNi1/3Mn1/3Co1/3O2 (x 1) and its aged products via magnetic and diffraction study

    SciTech Connect

    Mohanty, Debasish; Gabrisch, Heike

    2012-01-01

    The thermal stability of the layered oxide LiNi1/3Mn1/3Co1/3O2 and its delithiated product is studied by a combination of x-ray and electron diffraction, TEM imaging and magnetic measurements. Diffraction shows that a small fraction of the layered material converts to spinel phase following delithiation. More spinel phase is observed after thermal annealing. The morphology of the particle changes upon thermal annealing of delithiated materials. The selected area electron diffraction and the magnetic measurement results confirm the presence of Ni+2/Li+ disorder in the delithiated material, which increases upon thermal ageing. The oxidation states of the transition metal ions were determined from magnetic data. It is shown that the charge balance due TO removal of Li+ is maintained through oxidation of Ni+2 and that the oxidation states remain stable during subsequent annealing. No anti-ferromagnetic ordering or crystallographic in plane ordering of transition metal ions is observed. These results clearly describe the thermal degradation of LixNi1/3Mn1/3Co1/3O2 (x 1) occur through the significant microstructural changes.

  6. Microstructural investigation of LixNi1/3Mn1/3Co1/3O2 (x ≤ 1) and its aged products via magnetic and diffraction study

    NASA Astrophysics Data System (ADS)

    Mohanty, D.; Gabrisch, H.

    2012-12-01

    The thermal stability of the layered oxide LiNi1/3Mn1/3Co1/3O2 and its delithiated product is studied by a combination of X-ray and electron diffraction, TEM imaging and magnetic measurements. Diffraction shows that a small fraction of the layered material converts to spinel phase following delithiation. More spinel phase is observed after thermal annealing. The morphology of the particle changes upon thermal annealing of delithiated materials. The selected area electron diffraction and the magnetic measurement results confirm the presence of Ni+2/Li+ disorder in the delithiated material, which increases upon thermal ageing. The oxidation states of the transition metal ions were determined from magnetic data. It is shown that the charge balance due to removal of Li+ is maintained through oxidation of Ni+2 and that the oxidation states remain stable during subsequent annealing. No antiferromagnetic ordering or crystallographic in plane ordering of transition metal ions is observed. These results clearly describe the thermal degradation of LixNi1/3Mn1/3Co1/3O2 (x ≤ 1) occur through the significant microstructural changes.

  7. CDF experimental results on diffraction

    SciTech Connect

    Gallinaro, Michele; /Rockefeller U.

    2009-04-01

    Experimental results on diffraction from the Fermilab Tevatron collider obtained by the CDF experiment are reviewed and compared. We report on the diffractive structure function obtained from dijet production in the range 0 < Q{sup 2} < 10,000 GeV{sup 2}, and on the |t| distribution in the region 0 < |t| < 1 GeV{sup 2} for both soft and hard diffractive events up to Q{sup 2} {approx} 4,500 GeV{sup 2}. Results on single diffractive W/Z production, forward jets, and central exclusive production of both dijets and diphotons are also presented.

  8. Magnetic field measurements of a superconducting undulator for a Harmonic Generation FEL experiment at the NSLS

    SciTech Connect

    Solomon, L.; Ingold, G.; Ben-Zvi, I.; Krinsky, S.; Yu, L.H.; Sampson, W.; Robins, K.

    1993-07-01

    An 18mm period, 0.54 Tesla, 8mm gap superconducting undulator with both horizontal and vertical focusing has been built and tested. This magnet, which is fabricated in 25 cm length sections, is being tested for use in the radiator section (total magnet length of 1.5 m) of the Harmonic Generation Free Electron Laser experiment at the National Synchrotron Light Source - Accelerator Test Facility at Brookhaven National Lab., in collaboration with Grumman Corp. The measurement system is outlined, sources and estimates of errors are described, and some magnetic field data are presented and discussed.

  9. A LABORATORY EXPERIMENT OF MAGNETIC RECONNECTION: OUTFLOWS, HEATING, AND WAVES IN CHROMOSPHERIC JETS

    SciTech Connect

    Nishizuka, N.; Shimizu, T.; Hayashi, Y.; Tanabe, H.; Kuwahata, A.; Kaminou, Y.; Ono, Y.; Inomoto, M.

    2012-09-10

    Hinode observations have revealed intermittent recurrent plasma ejections/jets in the chromosphere. These are interpreted as a result of non-perfectly anti-parallel magnetic reconnection, i.e., component reconnection, between a twisted magnetic flux tube and the pre-existing coronal/chromospheric magnetic field, though the fundamental physics of component reconnection is not revealed. In this paper, we experimentally reproduced the magnetic configuration and investigated the dynamics of plasma ejections, heating, and wave generation triggered by component reconnection in the chromosphere. We set plasma parameters as in the chromosphere (density 10{sup 14} cm{sup -3}, temperature 5-10 eV, i.e., (5-10) Multiplication-Sign 10{sup 4} K, and reconnection magnetic field 200 G) using argon plasma. Our experiment shows bi-directional outflows with the speed of 5 km s{sup -1} at maximum, ion heating in the downstream area over 30 eV, and magnetic fluctuations mainly at 5-10 {mu}s period. We succeeded in qualitatively reproducing chromospheric jets, but quantitatively, we still have some differences between observations and experiments such as in jet velocity, total energy, and wave frequency. Some of them can be explained by the scale gap between solar and laboratory plasma, while the others are probably due to the difference in microscopy and macroscopy, collisionality, and the degree of ionization, which have not been achieved in our experiment.

  10. X-ray Absorption Spectroscopy and Coherent X-ray Diffraction Imaging for Time-Resolved Investigation of the Biological Complexes: Computer Modelling towards the XFEL Experiment

    NASA Astrophysics Data System (ADS)

    Bugaev, A. L.; Guda, A. A.; Yefanov, O. M.; Lorenz, U.; Soldatov, A. V.; Vartanyants, I. A.

    2016-05-01

    The development of the next generation synchrotron radiation sources - free electron lasers - is approaching to become an effective tool for the time-resolved experiments aimed to solve actual problems in various fields such as chemistry’ biology’ medicine’ etc. In order to demonstrate’ how these experiments may be performed for the real systems to obtain information at the atomic and macromolecular levels’ we have performed a molecular dynamics computer simulation combined with quantum chemistry calculations for the human phosphoglycerate kinase enzyme with Mg containing substrate. The simulated structures were used to calculate coherent X-ray diffraction patterns’ reflecting the conformational state of the enzyme, and Mg K-edge X-ray absorption spectra, which depend on the local structure of the substrate. These two techniques give complementary information making such an approach highly effective for time-resolved investigation of various biological complexes, such as metalloproteins or enzymes with metal-containing substrate, to obtain information about both metal-containing active site or substrate and the atomic structure of each conformation.

  11. Neutron powder diffraction study of nuclear and magnetic structures of multiferroic (Bi0.8Ba0.2)(Fe0.8Ti0.2)O3: Evidence for isostructural phase transition and magnetoelastic and magnetoelectric couplings

    NASA Astrophysics Data System (ADS)

    Singh, Anar; Senyshyn, Anatoliy; Fuess, Hartmut; Chatterji, Tapan; Pandey, Dhananjai

    2011-02-01

    We report here the results of a high-resolution neutron powder diffraction study on the multiferroic solid solution system (Bi0.8Ba0.2)(Fe0.8Ti0.2)O3 in the temperature range 4 to 700 K. Using irreducible representation theory to analyze the magnetic structure by Rietveld refinement, we show that the magnetic structure is collinear G-type antiferromagnetic. Further, we confirm the occurrence of an isostructural phase transition (IPT) accompanying the magnetic ordering around ˜625 K in (Bi0.8Ba0.2)(Fe0.8Ti0.2)O3. It is shown that as a result of the IPT, the positions of all the atoms change significantly in the magnetically ordered phase, leading to an excess polarization which scales linearly with the sublattice magnetization obtained by Rietveld refinement of the magnetic structure. Structural evidence for magnetoelastic coupling for the magnetic transitions below room temperature is also presented.

  12. A magnetic pulse does not affect homing pigeon navigation: a GPS tracking experiment.

    PubMed

    Holland, Richard; Filannino, Caterina; Gagliardo, Anna

    2013-06-15

    The cues by which homing pigeons are able to return to a home loft after displacement to unfamiliar release sites remain debated. A number of experiments in which migratory birds have been treated with a magnetic pulse have produced a disruption in their orientation, which argues that a ferrimagnetic sense is used for navigation in birds. One previous experiment has also indicated an effect of magnetic pulses on homing pigeon navigation, although with inconsistent results. Previous studies have shown that some magnetic-related information is transmitted by the trigeminal nerve to the brain in some bird species, including the homing pigeon. The function of this information is still unclear. It has been suggested that this information is important for navigation. Previous studies with trigeminal nerve lesioned homing pigeons have clearly shown that the lack of trigeminally mediated information, even if magnetic, is not crucial for homing performance. However, this result does not completely exclude the possibility that other ferrimagnetic receptors in the homing pigeon play a role in navigation. Additionally, recent studies on homing pigeons suggested the existence of a ferrimagnetic sense in a novel location presumably located in the inner ear (lagena). In the present study, we tested whether any ferrimagnetic magnetoreceptors, irrespective of their location in the bird's head, are involved in pigeons' homing. To do this, we treated homing pigeons with a strong magnetic pulse before release, tracked birds with GPS loggers and analyzed whether this treatment affected homing performance. In the single previous magnetic pulse experiment on homing pigeons, only initial orientation at a release site was considered and the results were inconsistent. We observed no effect of the magnetic pulse at any of the sites used on initial orientation, homing performance, tortuosity or track efficiency, which does not support a role for the ferrimagnetic sense in homing pigeon

  13. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment.

    PubMed

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-14

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising. PMID:26979686

  14. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment

    NASA Astrophysics Data System (ADS)

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-01

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

  15. High-resolution nuclear magnetic resonance measurements in inhomogeneous magnetic fields: A fast two-dimensional J-resolved experiment.

    PubMed

    Huang, Yuqing; Lin, Yung-Ya; Cai, Shuhui; Yang, Yu; Sun, Huijun; Lin, Yanqin; Chen, Zhong

    2016-03-14

    High spectral resolution in nuclear magnetic resonance (NMR) is a prerequisite for achieving accurate information relevant to molecular structures and composition assignments. The continuous development of superconducting magnets guarantees strong and homogeneous static magnetic fields for satisfactory spectral resolution. However, there exist circumstances, such as measurements on biological tissues and heterogeneous chemical samples, where the field homogeneity is degraded and spectral line broadening seems inevitable. Here we propose an NMR method, named intermolecular zero-quantum coherence J-resolved spectroscopy (iZQC-JRES), to face the challenge of field inhomogeneity and obtain desired high-resolution two-dimensional J-resolved spectra with fast acquisition. Theoretical analyses for this method are given according to the intermolecular multiple-quantum coherence treatment. Experiments on (a) a simple chemical solution and (b) an aqueous solution of mixed metabolites under externally deshimmed fields, and on (c) a table grape sample with intrinsic field inhomogeneity from magnetic susceptibility variations demonstrate the feasibility and applicability of the iZQC-JRES method. The application of this method to inhomogeneous chemical and biological samples, maybe in vivo samples, appears promising.

  16. Magnetic ordering in TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} studied by neutron diffraction and first-principles calculations

    SciTech Connect

    Staruch, M.; Sharma, V.; Ramprasad, R.; Cruz, C. dela; Jain, M.

    2014-07-21

    The structure and magnetic ordering of bulk TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} was revealed through bulk magnetization and neutron diffraction measurements, and first-principles calculations, respectively. G-type antiferromagnetic ordering of Mn{sup 3+} and Cr{sup 3+} moments was observed in the neutron diffraction data below Néel temperature T{sub N} ∼ 84 K. In addition, below ∼40 K, short-range magnetic ordering was identified correlating to a ferromagnetic component due to the canting of the moments along the c-axis. The spin configuration is consistent with the first-principles calculations. The magnetic structure revealed in the present TbMn{sub 0.5}Cr{sub 0.5}O{sub 3} sample is distinct from that observed for both end members TbMnO{sub 3} and TbCrO{sub 3}.

  17. Lattice collapse and quenching of magnetism in CaFe[subscript 2]As[subscript 2] under pressure: A single-crystal neutron and x-ray diffraction investigation

    SciTech Connect

    Goldman, A.I.; Kreyssig, A.; Prokeš, K.; Pratt, D.K.; Argyriou, D.N.; Lynn, J.W.; Nandi, S.; Kimber, S.A.J.; Chen, Y.; Lee, Y.B.; Samolyuk, G.; Leão, J.B.; Poulton, S.J.; Bud'ko, S.L.; Ni, N.; Canfield, P.C.; Harmon, B.N.; McQueeney, R.J.

    2009-06-12

    Single-crystal neutron and high-energy x-ray diffraction measurements have identified the phase lines corresponding to transitions among the ambient-pressure paramagnetic tetragonal (T), the antiferromagnetic orthorhombic (O), and the nonmagnetic collapsed tetragonal (cT) phases of CaFe{sub 2}As{sub 2}. We find no evidence of additional structures for pressures of up to 2.5 GPa (at 300 K). Both the T-cT and O-cT transitions exhibit significant hysteresis effects, and we demonstrate that coexistence of the O and cT phases can occur if a nonhydrostatic component of pressure is present. Measurements of the magnetic diffraction peaks show no change in the magnetic structure or ordered moment as a function of pressure in the O phase, and we find no evidence of magnetic ordering in the cT phase. Band-structure calculations show that the transition into the cT phase results in a strong decrease in the iron 3d density of states at the Fermi energy, consistent with a loss of the magnetic moment.

  18. Self-generated Magnetic Fields in Blast-wave Driven Rayleigh-Taylor Experiments

    NASA Astrophysics Data System (ADS)

    Flaig, Markus; Plewa, Tomasz

    2014-10-01

    We study the generation of magnetic fields via the Biermann battery effect in blast-wave driven Rayleigh-Taylor experiments. Previous estimates have shown that in a typical experiment, one should expect fields in the MG range to be generated, with the potential to influence the Rayleigh-Taylor morphology. We perform two- and three-dimensional numerical simulations, where we solve the extended set of MHD equations known as the Braginskii equations. The simulation parameters reflect the physical conditions in past experiments performed on the OMEGA laser and potential future experiments on the NIF laser facility. When neglecting the friction force between electrons and ions in the simulations, magnetic fields of the order of a few 0.1 MG (with a plasma smaller than 1000) are generated, and are found to be dynamically significant. However, it turns out that once the friction force is included, the magnetic fields become much smaller (with a plasma beta greater than 100000) which have negligible influence on the dynamics of the system. Our results therefore indicate that, contrary to previous speculations, it is highly unlikely that self-generated magnetic fields can influence the morphology of a typical blast-wave driven Rayleigh-Taylor experiment. M.F. and T.P. were supported by the DOE Grant DE-FG52- 09NA29548 and the NSF Grant AST-1109113. This research used resources of the National Energy Re.

  19. Pulsed Polarimetry and magnetic sensing on the Magnetized Shock Experiment (MSX)

    NASA Astrophysics Data System (ADS)

    Smith, R. J.; Hutchinson, T. M.; Weber, T. E.; Taylor, S. F.; Hsu, S. C.

    2014-10-01

    MSX is uniquely positioned to generate the conditions for collision-less magnetized supercritical shocks with Alvenic Mach numbers (MA) of the order 10 and higher. Significant operational strides have been made in forming plasmas over wide parameter ranges: (Te + Ti) of 10-200 eV, average neof 5-60×10+21 m-3, speeds up to 150 km/s and fields up to 1T with a highest plasma flow MA of 5 to date. The MSX plasma is unique in regards to large plasma size of 10 cm and average β higher than 0.8 making the FRC and the magnetized shock structure candidates for the application of Pulsed Polarimetry, a polarization sensitive Lidar technique. The shock dynamics are presently being investigated using internal probes, interferometry and imaging. Internal probe results and an assessment of the shock parameters will dictate the use of the UW pulsed polarimeter system in which internal ne, Teand B are to be measured. Recent results will be presented. Supported by DOE Office of Fusion Energy Sciences Funding DE-FOA-0000755.

  20. Neutron-diffraction measurements of magnetic order and a structural transition in the parent BaFe2As2 compound of FeAs-based high-temperature superconductors.

    PubMed

    Huang, Q; Qiu, Y; Bao, Wei; Green, M A; Lynn, J W; Gasparovic, Y C; Wu, T; Wu, G; Chen, X H

    2008-12-19

    The recent discovery of superconductivity in (Ba,K)Fe2As2, which crystallizes in the ThCr2Si2 (122) structure as compared with the LnFeAsO (Ln is lanthanide) systems that possess the ZrCuSiAs (1111) structure, demonstrates the exciting potential of the FeAs-based materials for high-T{C} superconductivity. Here we report neutron diffraction studies that show a tetragonal-to-orthorhombic distortion associated with the onset of q=(101) antiferromagnetic order in BaFe2As2, with a saturation moment 0.87(3)micro {B} per Fe that is orientated along the longer a axis of the ab planes. The simultaneous first-order structural and magnetic transition is in contrast with the separated transitions previously reported in the 1111-type materials. The orientational relation between magnetic alignment and lattice distortion supports a multiorbital nature for the magnetic order.

  1. Neutron-diffraction measurements of magnetic order and a structural transition in the parent BaFe2As2 compound of FeAs-based high-temperature superconductors.

    PubMed

    Huang, Q; Qiu, Y; Bao, Wei; Green, M A; Lynn, J W; Gasparovic, Y C; Wu, T; Wu, G; Chen, X H

    2008-12-19

    The recent discovery of superconductivity in (Ba,K)Fe2As2, which crystallizes in the ThCr2Si2 (122) structure as compared with the LnFeAsO (Ln is lanthanide) systems that possess the ZrCuSiAs (1111) structure, demonstrates the exciting potential of the FeAs-based materials for high-T{C} superconductivity. Here we report neutron diffraction studies that show a tetragonal-to-orthorhombic distortion associated with the onset of q=(101) antiferromagnetic order in BaFe2As2, with a saturation moment 0.87(3)micro {B} per Fe that is orientated along the longer a axis of the ab planes. The simultaneous first-order structural and magnetic transition is in contrast with the separated transitions previously reported in the 1111-type materials. The orientational relation between magnetic alignment and lattice distortion supports a multiorbital nature for the magnetic order. PMID:19113744

  2. Stochastic reversal dynamics of two interacting magnetic dipoles: A simple model experiment.

    PubMed

    Plihon, Nicolas; Miralles, Sophie; Bourgoin, Mickael; Pinton, Jean-François

    2016-07-01

    We report an experimental study of the dynamics of two coupled magnetic dipoles. The experiment consists in two coplanar permanent disk magnets separated by a distance d, each allowed to rotate on a fixed parallel axis-each magnet's axis being perpendicular to its dipolar moment vector. A torque of adjustable strength can be externally applied to one of the magnets, the other magnet being free. The driving torque may be time-independent or temporally fluctuating. We study the influence of the parameters of the driving torque on the dynamics of the coupled system, in particular the emergence of dynamical regimes such as stochastic reversals. We report transitions between stationary and stochastic reversal regimes. All the observed features can be understood by a simple mechanical dynamical model. The transition between statistically stationary regimes and reversals is explained introducing an effective potential energy incorporating both the coupling between magnets and the external driving. Relations between this simple experimental model with macroscopic models of magnetic spin coupling, as well as with chaotic reversals of turbulent dynamos, are discussed. PMID:27575140

  3. Measurement and tricubic interpolation of the magnetic field for the OLYMPUS experiment

    NASA Astrophysics Data System (ADS)

    Bernauer, J. C.; Diefenbach, J.; Elbakian, G.; Gavrilov, G.; Goerrissen, N.; Hasell, D. K.; Henderson, B. S.; Holler, Y.; Karyan, G.; Ludwig, J.; Marukyan, H.; Naryshkin, Y.; O'Connor, C.; Russell, R. L.; Schmidt, A.; Schneekloth, U.; Suvorov, K.; Veretennikov, D.

    2016-07-01

    The OLYMPUS experiment used a 0.3 T toroidal magnetic spectrometer to measure the momenta of outgoing charged particles. In order to accurately determine particle trajectories, knowledge of the magnetic field was needed throughout the spectrometer volume. For that purpose, the magnetic field was measured at over 36,000 positions using a three-dimensional Hall probe actuated by a system of translation tables. We used these field data to fit a numerical magnetic field model, which could be employed to calculate the magnetic field at any point in the spectrometer volume. Calculations with this model were computationally intensive; for analysis applications where speed was crucial, we pre-computed the magnetic field and its derivatives on an evenly spaced grid so that the field could be interpolated between grid points. We developed a spline-based interpolation scheme suitable for SIMD implementations, with a memory layout chosen to minimize space and optimize the cache behavior to quickly calculate field values. This scheme requires only one-eighth of the memory needed to store necessary coefficients compared with a previous scheme (Lekien and Marsden, 2005 [1]). This method was accurate for the vast majority of the spectrometer volume, though special fits and representations were needed to improve the accuracy close to the magnet coils and along the toroidal axis.

  4. Quench calculations for the superconducting dipole magnet of CBM experiment at FAIR

    NASA Astrophysics Data System (ADS)

    Kurilkin, P.; Akishin, P.; Bychkov, A.; Floch, E.; Gusakov, Yu.; Ladygin, V.; Malakhov, A.; Moritz, G.; Ramakers, H.; Senger, P.; Shabunov, A.; Szwangruber, P.; Toral, F.

    2016-08-01

    The scientific mission of the Compressed Baryonic Matter (CBM) experiment is the study of the nuclear matter properties at the high baryon densities in heavy ion collisions at the Facility of Antiproton and Ion Research (FAIR) in Darmstadt. The 5.15 MJ superconducting dipole magnet will be used in the silicon tracking system of the CBM detector. It will provide a magnetic field integral of 1 Tm which is required to obtain a momentum resolution of 1% for the track reconstruction. This paper presents quench modeling and evaluation of candidate protection schemes for the CBM dipole magnet. Two quench programs based on finite-difference method were used in simulation. One of them is currently used at GSI, and the other based on CIEMAT (Madrid, Spain) was modified to perform quench calculation for the CBM magnet.

  5. Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

    NASA Astrophysics Data System (ADS)

    Manuel, M. J.-E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; Drake, R. P.; Pollock, B. B.; Park, J.; Hazi, A. U.; Williams, G. J.; Chen, H.

    2015-12-01

    Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. This result is a topic of ongoing investigation.

  6. Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

    DOE PAGES

    Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; et al

    2014-08-20

    Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysicalmore » systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.« less

  7. Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

    SciTech Connect

    Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; Drake, R. P.; Pollock, B. B.; Park, J.; Hazi, A. U.; Williams, G. J.; Chen, H.

    2014-08-20

    Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.

  8. Interior Vector Magnetic Field Monitoring via External Measurements for the SNS Neutron EDM Experiment

    NASA Astrophysics Data System (ADS)

    Nouri, Nima; Brown, Michael; Carr, Robert; Filippone, Bradley; Osthelder, Charles; Plaster, Bradley; Slutsky, Simon; Swank, Christopher

    2015-10-01

    A prototype of a magnetic field monitoring system designed to reconstruct the vector magnetic field components (and, hence, all nine of the ∂Bi / ∂xj field gradients) within the interior measurement fiducial volume solely from external measurements is under development for the SNS neutron EDM experiment. A first-generation room-temperature prototype array has already been tested. A second-generation prototype array consisting of 12 cryogenic-compatible fluxgate magnetometer probes will be deployed within the cold region of the experiment's 1 / 3 -scale cryogenic magnet testing apparatus. We will report progress towards the development of this second-generation prototype. This work was supported in part by the U. S. Department of Energy Office of Nuclear Physics under Award No. DE-FG02-08ER41557.

  9. Incommensurate Magnetic Structure in the Cubic Noncentrosymmetric Ternary Compound Pr5Ru3Al2

    NASA Astrophysics Data System (ADS)

    Makino, Koya; Okuyama, Daisuke; Avdeev, Maxim; Sato, Taku J.

    2016-07-01

    Magnetic susceptibility and neutron powder diffraction experiments have been performed on the noncentrosymmetric ternary compound Pr5Ru3Al2. The previously reported ferromagnetic transition at 24 K was not detected in our improved-quality samples. Instead, magnetic ordering was observed in the DC magnetic susceptibility at T{c} ≃ 3.8 K. The neutron powder diffraction experiment further indicates that an incommensurate magnetic structure is established below Tc with the magnetic modulation vector {{q}} ≃ (0.066,0.066,0.066) (r.l.u.). A candidate for the magnetic structure is proposed using representation analysis.

  10. FLASH MHD simulations of experiments that study shock-generated magnetic fields

    NASA Astrophysics Data System (ADS)

    Tzeferacos, P.; Fatenejad, M.; Flocke, N.; Graziani, C.; Gregori, G.; Lamb, D. Q.; Lee, D.; Meinecke, J.; Scopatz, A.; Weide, K.

    2015-12-01

    We summarize recent additions and improvements to the high energy density physics capabilities in FLASH, highlighting new non-ideal magneto-hydrodynamic (MHD) capabilities. We then describe 3D Cartesian and 2D cylindrical FLASH MHD simulations that have helped to design and analyze experiments conducted at the Vulcan laser facility. In these experiments, a laser illuminates a carbon rod target placed in a gas-filled chamber. A magnetic field diagnostic (called a Bdot) employing three very small induction coils is used to measure all three components of the magnetic field at a chosen point in space. The simulations have revealed that many fascinating physical processes occur in the experiments. These include megagauss magnetic fields generated by the interaction of the laser with the target via the Biermann battery mechanism, which are advected outward by the vaporized target material but decrease in strength due to expansion and resistivity; magnetic fields generated by an outward expanding shock via the Biermann battery mechanism; and a breakout shock that overtakes the first wave, the contact discontinuity between the target material and the gas, and then the initial expanding shock. Finally, we discuss the validation and predictive science we have done for this experiment with FLASH.

  11. Quantitative two-dimensional HSQC experiment for high magnetic field NMR spectrometers

    NASA Astrophysics Data System (ADS)

    Koskela, Harri; Heikkilä, Outi; Kilpeläinen, Ilkka; Heikkinen, Sami

    2010-01-01

    The finite RF power available on carbon channel in proton-carbon correlation experiments leads to non-uniform cross peak intensity response across carbon chemical shift range. Several classes of broadband pulses are available that alleviate this problem. Adiabatic pulses provide an excellent magnetization inversion over a large bandwidth, and very recently, novel phase-modulated pulses have been proposed that perform 90° and 180° magnetization rotations with good offset tolerance. Here, we present a study how these broadband pulses (adiabatic and phase-modulated) can improve quantitative application of the heteronuclear single quantum coherence (HSQC) experiment on high magnetic field strength NMR spectrometers. Theoretical and experimental examinations of the quantitative, offset-compensated, CPMG-adjusted HSQC (Q-OCCAHSQC) experiment are presented. The proposed experiment offers a formidable improvement to the offset performance; 13C offset-dependent standard deviation of the peak intensity was below 6% in range of ±20 kHz. This covers the carbon chemical shift range of 150 ppm, which contains the protonated carbons excluding the aldehydes, for 22.3 T NMR magnets. A demonstration of the quantitative analysis of a fasting blood plasma sample obtained from a healthy volunteer is given.

  12. Structure enhancement methodology using theory and experiment: gas-phase molecular structures using a dynamic interaction between electron diffraction, molecular mechanics, and ab initio data.

    PubMed

    Kafka, Graeme R; Masters, Sarah L; Rankin, David W H

    2007-07-01

    A new method of incorporating ab initio theoretical data dynamically into the gas-phase electron diffraction (GED) refinement process has been developed to aid the structure determination of large, sterically crowded molecules. This process involves calculating a set of differences between parameters that define the positions of peripheral atoms (usually hydrogen), as determined using molecular mechanics (MM), and those which use ab initio methods. The peripheral-atom positions are then updated continually during the GED refinement process, using MM, and the returned positions are modified using this set of differences to account for the differences between ab initio and MM methods, before being scaled back to the average parameters used to define them, as refined from experimental data. This allows the molecule to adopt a completely asymmetric structure if required, without being constrained by the MM parametrization, whereas the calculations can be performed on a practical time scale. The molecular structures of tri-tert-butylphosphine oxide and tri-tert-butylphosphine imide have been re-examined using this new technique, which we call SEMTEX (Structure Enhancement Methodology using Theory and EXperiment).

  13. Neutron diffraction and the electronic properties of BaFe2Se3

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.; Khalyavin, D. D.; van der Laan, G.

    2016-01-01

    It is argued on the basis of previously published experimental data that, the magnetic space-group Cac (#9.41) is the correct description of magnetically ordered BaFe2Se3. The corresponding crystal class m1‧ allows axial and polar dipoles and forbids bulk ferromagnetism. Magneto-electric multipoles that are both time-odd and parity-odd are allowed, e.g., a magnetic charge (monopole) and an anapole (magnetic toroidal dipole). The experimental observation of magneto-electric multipoles must shed light on valence electrons involved in bonding, including charge transfer using 3d(Fe) and p-states of ligand ions. We provide the appropriate structure factors for the Bragg diffraction neutrons, together with estimates of atomic form factors. Structure factors for resonant x-ray Bragg diffraction are also considered, because the analysis of successful experiments will yield complementary information about electronic properties. Magneto-electric multipoles, over and above those that contribute to magnetic neutron diffraction, include the magnetic monopole. A time-odd, parity-even monopole created from the magnetic dipole and an electric toroidal dipole, which is a manifestation of a structural rotation, is allowed in BaFe2Se3 but it is not visible in diffraction, nor is the corresponding dipole.

  14. Biological Experiments in Microgravity Conditions Using Magnetic Micro- and Nano-Particles

    NASA Astrophysics Data System (ADS)

    Nechitailo, Galina S.; Kuznetsov, Anatoli; Kuznetsov, Oleg

    2016-07-01

    Gravity affects all living organisms on Earth, and plays a role in multiple processes in them. In microgravity conditions (e.g., on board of a spacecraft) many of these processes are disturbed, e.g., spatial orientation is lost, mass and heat exchange is distorted, many adaptive mechanisms no longer function, etc. Negation of these adverse effects by creation of pseudo-gravity to by centrifugation is complicated, expensive and unpractical. We propose to use naturally occurring magnetic heterogeneity of all living cells and high gradient magnetic fields as an alternative approach to negating the adverse effects of microgravity on living systems. In non-uniform magnetic field, magnetically heterogeneous objects experience a system of ponderomotive forces. For a weak magnetic particle, the net ponderomotive magnetic force: Fm = Δχ•V•grad(H2/2), where Δχ is the difference of susceptibilities of the particle and the surrounding media, V is the volume of the particle, grad(H2/2) is the dynamic factor of the magnetic field. We studied magnetic heterogeneity of plant gravity receptor cells, prepared and conducted experiments on board of the space station "Mir" on providing a gravity-like stimulus for flax seedlings using high gradient magnetic field ("Magnetogravistat" experiment). Later, a more sophisticated version of this experiment was flown on STS-107. These experiments provided new data on the mechanisms of plant gravity reception and created a method for substituting gravity for a living organism by a force of a different physical nature, to negate the adverse effects of microgravity. Since the ponderomotive force is proportional to the dynamic factor of the field grad(H2/2), the stronger the field, and the faster it changes over distance, the higher is the dynamic factor and the stronger the ponderomotive force. Therefore, in the small vicinity of a small ferromagnetic particle (preferably metallic micro or nano-particles), the forces are very significant

  15. Neutron diffraction study of the magnetic ordering of the Cu sup ++ spins in Nd sub 1. 5 Ba sub 1. 5 Cu sub 3 O sub 6+x

    SciTech Connect

    Moudden, A.H.; Hennion, B. - Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette ); Schweiss, P. - Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette Kernforschungszentrum Karlsruhe GmbH . Inst. fuer Nukleare Festkoerperphysik); Gehring, P.M.; Shirane, G. (Brookhaven National Lab., Upton, NY (

    1991-01-01

    Elastic neutron scattering experiments performed on single crystals of Nd{sub 1.5}Ba{sub 1.5}Cu{sub 3}O{sub 6+y} reveal successive antiferromagnetic (AF) ordering of the Cu{sup ++} spins. The as grown single crystals show an AF structure characterized by a Neel temperature T{sub N1} {approximately} 390K and a magnetic wave vector (1/2 1/2 0) referring to the tetragonal structure of NdBa{sub 2}Cu{sub 3}O{sub 6}. As the temperature is lowered below T{sub N2} {approximately} 150K, a spin reorientation develops and a second AF ordering with (1/2 1/2 1/2) wave vector is stabilized. When the samples are oxygenated the tetragonal symmetry and the Neel temperature T{sub N1} remain unchanged, whereas the spin reorientation at T{sub N2} is suppressed. The results indicate that the Nd/Ba substitution increases the stability of the tetragonal structure upon the oxygen content. This may induce new possibilities of local oxygen ordering that favour the presence of holes in the deficient layer.

  16. Computational modeling of pulsed-power-driven magnetized target fusion experiments

    SciTech Connect

    Sheehey, P.; Kirkpatrick, R.; Lindemuth, I.

    1995-08-01

    Direct magnetic drive using electrical pulsed power has been considered impractically slow for traditional inertial confinement implosion of fusion targets. However, if the target contains a preheated, magnetized plasma, magnetothermal insulation may allow the near-adiabatic compression of such a target to fusion conditions on a much slower time scale. 100-MJ-class explosive flux compression generators with implosion kinetic energies far beyond those available with conventional fusion drivers, are an inexpensive means to investigate such magnetized target fusion (MTF) systems. One means of obtaining the preheated and magnetized plasma required for an MTF system is the recently reported {open_quotes}MAGO{close_quotes} concept. MAGO is a unique, explosive-pulsed-power driven discharge in two cylindrical chambers joined by an annular nozzle. Joint Russian-American MAGO experiments have reported D-T neutron yields in excess of 10{sup 13} from this plasma preparation stage alone, without going on to the proposed separately driven NM implosion of the main plasma chamber. Two-dimensional MED computational modeling of MAGO discharges shows good agreement to experiment. The calculations suggest that after the observed neutron pulse, a diffuse Z-pinch plasma with temperature in excess of 100 eV is created, which may be suitable for subsequent MTF implosion, in a heavy liner magnetically driven by explosive pulsed power. Other MTF concepts, such as fiber-initiated Z-pinch target plasmas, are also being computationally and theoretically evaluated. The status of our modeling efforts will be reported.

  17. Laboratory experiments investigating magnetic field production via the Weibel instability in interpenetrating plasma flows

    NASA Astrophysics Data System (ADS)

    Huntington, Channing; Fiuza, Frederico; Ross, James Steven; Zylstra, Alex; Pollock, Brad; Drake, R. Paul; Froula, Dustin; Gregori, Gianluca; Kugland, Nathan; Kuranz, Carolyn; Levy, Matthew; Li, Chikang; Meinecke, Jena; Petrasso, Richard; Remington, Bruce; Ryutov, Dmitri; Sakawa, Youichi; Spitkovsky, Anatoly; Takabe, Hideke; Turnbull, David; Park, Hye-Sook

    2015-08-01

    Astrophysical collisionless shocks are often associated with the presence of strong magnetic fields in a plasma flow. The magnetic fields required for shock formation may either be initially present, for example in supernova remnants or young galaxies, or they may be self-generated in systems such as gamma-ray bursts (GRBs). In the case of GRB outflows, the intense magnetic fields are greater than those seeded by the GRB progenitor or produced by misaligned density and temperature gradients in the plasma flow (the Biermann-battery effect). The Weibel instability is one candidate mechanism for the generation of sufficiently strong fields to create a collisionless shock. Despite their crucial role in astrophysical systems, observation of the magnetic fields produced by Weibel instabilities in experiments has been challenging. Using a proton probe to directly image electromagnetic fields, we present evidence of Weibel-generated magnetic fields that grow in opposing, initially unmagnetized plasma flows from laser-driven laboratory experiments. Three-dimensional particle-in-cell simulations reveal that the instability efficiently extracts energy from the plasma flows, and that the self-generated magnetic energy reaches a few percent of the total energy in the system. This result demonstrates an experimental platform suitable for the investigation of a wide range of astrophysical phenomena, including collisionless shock formation in supernova remnants, large-scale magnetic field amplification, and the radiation signature from gamma-ray bursts.This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  18. SUPERCONDUCTING COMBINED FUNCTION MAGNET SYSTEM FOR J-PARC NEUTRINO EXPERIMENT.

    SciTech Connect

    OGITSU, T.; AJIMA, Y.; ANERELLA, M.; ESCALLIER, J.; GANETIS, G.; GUPTA, R.; HAGEDOM, D.; HARRISON, M.; HIGASHI, N.; IWAMOTO, Y.; ICHIKAWA, A.; JAIN, A.; KIMURA, N.; KOBAYASHI, T.; MAKIDA, Y.; MURATORE, J.; NAKAMOTO, T.; OHHATA, H.; TAKASAKI, N.; TANAKA, K.; TERASHIMA, A.; YAMOMOTO, A.; OBANA, T.; PARKER, B.; WANDERER, P.

    2004-10-03

    The J-PARC Neutrino Experiment, the construction of which starts in JFY 2004, will use a superconducting magnet system for its primary proton beam line. The system, which bends the 50 GeV 0.75 MW proton beam by about 80 degrees, consists of 28 superconducting combined function magnets. The magnets utilize single layer left/right asymmetric coils that generate a dipole field of 2.6 T and a quadrupole field of 18.6 T/m with the operation current of about 7.35 kA. The system also contains a few conduction cooled superconducting corrector magnets that serve as vertical and horizontal steering magnets. All the magnets are designed to provide a physical beam aperture of 130 mm in order to achieve a large beam acceptance. Extensive care is also required to achieve safe operation with the high power proton beam. The paper summarizes the system design as well as some safety analysis results.

  19. Development of a Split Bitter-type Magnet System for Dusty Plasma Experiments

    NASA Astrophysics Data System (ADS)

    Bates, Evan; Romero-Talamas, Carlos A.; Birmingham, William J.; Rivera, William F.

    2014-10-01

    A 10 Tesla Bitter-type magnetic system is under development at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County (UMBC). We present here an optimization technique that uses differential evolution to minimize the omhic heating produced by the coils, while constraining the magnetic field in the experimental volume. The code gives us the optimal dimensions for the coil system including: coil length, turn thickness, disks radii, resistance, and total current required for a constant magnetic field. Finite element parametric optimization is then used to establish the optimal design for water cooling holes. Placement of the cooling holes will also take into consideration the magnetic forces acting on the copper alloy disks to ensure the material strength is not compromised during operation. The proposed power and cooling water delivery subsystems for the coils are also presented. Upon completion and testing of the magnet system, planned experiments include the propagation of magnetized waves in dusty plasma crystals under various boundary conditions, and viscosity in rotational shear flow, among others.

  20. Colored Diffraction Catastrophes

    NASA Astrophysics Data System (ADS)

    Berry, M. V.; Klein, S.

    1996-03-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences.

  1. Colored diffraction catastrophes.

    PubMed Central

    Berry, M V; Klein, S

    1996-01-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences. Images Fig. 1 Fig. 2 Fig. 3 Fig. 6 Fig. 8 Fig. 9 Fig. 10 PMID:11607642

  2. FLASH Hydrodynamic Simulations of Experiments to Explore the Generation of Cosmological Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Scopatz, Anthony; Fatenejad, Milad; Flocke, Norbert; Gregori, Gianluca; Lamb, Don; Lee, Dongwook; Meineke, Jena; Tzeferacos, Petros; Weide, Klaus

    2012-10-01

    Magnetic fields are ubiquitous throughout the universe. However, the origin and strength of these fields are not fully understood. A promising mechanism for the origin of seed fields is the asymmetric shocks that occur in hierarchical structure formation when smaller halos merge to form galaxies and galaxies merge to form clusters of galaxies. The seed fields are generated by the Biermann battery mechanism. The COSMOLAB team are conducting experiments to investigate the generation of magnetic fields by asymmetric shocks. These experiments involve laser illumination of a foil target, driving a shock into a gas-filled chamber, and a variety of plasma and magnetic field diagnostics. Hydrodynamic-only simulations are useful because the shock-generated magnetic fields are not dynamically important. In this paper, we describe hydrodynamic simulations of the experiment conducted using the FLASH code. The scientific objective of these simulations is to explore the sensitivity of the properties of the jet-like shock to target composition, thickness, and lateral extent.

  3. FLASH Magnetohydrodynamic Simulations of Experiments to Explore the Generation of Cosmological Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Tzeferacos, Petros; Fatenejad, Milad; Flocke, Norbert; Gregori, Gianluca; Lamb, Donald Q.; Lee, Dongwook; Meinecke, Jena; Scopatz, Anthony; Weide, Klaus

    2012-10-01

    Magnetic fields are ubiquitous throughout the universe. However, the origin and strength of these fields are not fully understood. A promising mechanism for the origin of seed fields is the asymmetric shocks that occur in hierarchical structure formation when smaller halos merge to form galaxies and galaxies merge to form clusters of galaxies. The seed fields are generated by the Biermann battery mechanism. The COSMOLAB team of the University of Oxford is conducting experiments to investigate the generation of magnetic fields by asymmetric shocks. These experiments involve the laser illumination of a foil target, driving a shock into a gas-filled chamber, and a variety of plasma and magnetic field diagnostics. In this paper, we describe magnetohydrodynamic simulations of the experiment carried out using the FLASH code. The scientific objective of these simulations is to explore the morphology and strength of the magnetic fields generated by ablation of target material by the laser, and by the jet-like shock that is produced on the opposite side of the target.

  4. The generation and amplification of intergalactic magnetic fields in analogue laboratory experiments with high power lasers

    NASA Astrophysics Data System (ADS)

    Gregori, G.; Reville, B.; Miniati, F.

    2015-11-01

    The advent of high-power laser facilities has, in the past two decades, opened a new field of research where astrophysical environments can be scaled down to laboratory dimensions, while preserving the essential physics. This is due to the invariance of the equations of magneto-hydrodynamics to a class of similarity transformations. Here we review the relevant scaling relations and their application in laboratory astrophysics experiments with a focus on the generation and amplification of magnetic fields in cosmic environment. The standard model for the origin of magnetic fields is a multi stage process whereby a vanishing magnetic seed is first generated by a rotational electric field and is then amplified by turbulent dynamo action to the characteristic values observed in astronomical bodies. We thus discuss the relevant seed generation mechanisms in cosmic environment including resistive mechanism, collision-less and fluid instabilities, as well as novel laboratory experiments using high power laser systems aimed at investigating the amplification of magnetic energy by magneto-hydrodynamic (MHD) turbulence. Future directions, including efforts to model in the laboratory the process of diffusive shock acceleration are also discussed, with an emphasis on the potential of laboratory experiments to further our understanding of plasma physics on cosmic scales.

  5. STX (Spherical Torus Experiment) magnet fabrication and testing to 16 T

    SciTech Connect

    McManamy, T.J.; Benson, R.D.; Brown, R.L.; Henkel, G.H.; Lazarus, E.A.; Williamson, D.E.; Wilson, C.T. Jr.

    1988-01-01

    A prototype ohmic heating coil for the proposed Spherical Torus Experiment (STX) has been designed, fabricated, and successfully tested to 16 T, well above its design operating field and stress levels. The conductor material was Glidcop Al-15 with a copper tube for water cooling soldered into a groove. The magnet winding inner and outer radii were 7.5 cm and 14.2 cm, respectively, and the axial length was 48 cm. The magnet heated to approximately 90/degree/C during a pulse and was cooled within 2 min. All design and performance goals were met or exceeded. 5 refs., 10 figs.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. Interior Vector Magnetic Field Monitoring for the SNS Neutron EDM Experiment

    NASA Astrophysics Data System (ADS)

    Nouri, Nima; Plaster, Brad

    2014-09-01

    A concept has been developed which provides for a real-time determination of the spatial dependence of the vector components of the magnetic field (and, hence, the ∂Bi / ∂xj field gradients) within the interior fiducial volume of the SNS neutron EDM experiment solely from exterior measurements at fixed discrete locations. This technique will be especially important during the operation of the experiment, when direct measurements of the field gradients present within the fiducial volume will not be physically possible. Our method, which is based on the solution to the Laplace Equation, is completely general and does not require the field to possess any type of symmetry. We describe the concept and our systematic approach for optimizing the locations of these exterior measurements. We also present results from prototyping studies of a field monitoring system deployed within a half-scale prototype of the experiment's magnetic field environment. A concept has been developed which provides for a real-time determination of the spatial dependence of the vector components of the magnetic field (and, hence, the ∂Bi / ∂xj field gradients) within the interior fiducial volume of the SNS neutron EDM experiment solely from exterior measurements at fixed discrete locations. This technique will be especially important during the operation of the experiment, when direct measurements of the field gradients present within the fiducial volume will not be physically possible. Our method, which is based on the solution to the Laplace Equation, is completely general and does not require the field to possess any type of symmetry. We describe the concept and our systematic approach for optimizing the locations of these exterior measurements. We also present results from prototyping studies of a field monitoring system deployed within a half-scale prototype of the experiment's magnetic field environment. This work was supported in part by the U.S. Department of Energy Office of

  8. Experiment definition and integration study for the accommodation of magnetic spectrometer payload on Spacelab/shuttle missions

    NASA Technical Reports Server (NTRS)

    Buffington, A.

    1978-01-01

    A super-cooled magnetic spectrometer for a cosmic-ray experiment is considered for application in the high energy astronomical observatory which may be used on a space shuttle spacelab mission. New cryostat parameters are reported which are appropriate to shuttle mission weight and mission duration constraints. Since a super-conducting magnetic spectrometer has a magnetic fringe field, methods for shielding sensitive electronic and mechanical components on nearby experiments are described.

  9. Nanosecond x-Ray diffraction from polycrystalline and amorphous materials in a pinhole camera geometry suitable for laser shock compression experiments

    SciTech Connect

    Hawreliak, J.; Lorenzana, H. E.; Remington, B. A.; Lukezic, S.; Wark, J. S.

    2007-08-15

    Nanosecond pulses of quasimonochromatic x-rays emitted from the K shell of ions within a laser-produced plasma are of sufficient spectral brightness to allow single-shot recording of powder diffraction patterns from thin foils of order millimeter diameter. Strong diffraction signals have been observed in a cylindrical pinhole camera arrangement from both polycrystalline and amorphous foils, and the experimental arrangement and foil dimensions are such that they allow for laser shocking or quasi-isentropic loading of the foil during the diffraction process.

  10. Nanosecond x-ray diffraction from polycrystalline and amorphous materials in a pinhole camera geometry suitable for laser shock compression experiments.

    PubMed

    Hawreliak, J; Lorenzana, H E; Remington, B A; Lukezic, S; Wark, J S

    2007-08-01

    Nanosecond pulses of quasimonochromatic x-rays emitted from the K shell of ions within a laser-produced plasma are of sufficient spectral brightness to allow single-shot recording of powder diffraction patterns from thin foils of order millimeter diameter. Strong diffraction signals have been observed in a cylindrical pinhole camera arrangement from both polycrystalline and amorphous foils, and the experimental arrangement and foil dimensions are such that they allow for laser shocking or quasi-isentropic loading of the foil during the diffraction process.

  11. Diffractive processes in antiproton-proton collision at √s = 1.96 TeV in the D0 experiment

    SciTech Connect

    Otec, Roman

    2006-01-01

    A first study of single diffractive central high-pT dijet events in p$\\bar{p}$ collisions at center-of-mass energy √s = 1.96 TeV is presented, using data recorded by the D0 detector at the Tevatron during RunIIa in 2002-2004. The total integrated luminosity corresponding to the data sample is 398 pb-1. A diffractive sample is selected using a rapidity gap approach. A precise definition of the rapidity gap constitutes the first part of the thesis. The rapidity gap is defined by means of two parts of the D0 detector--luminosity detectors and calorimeter. Luminosity detectors serve as a basic indicators of diffractive candidates and the calorimeter is used to confirm the low energy activity in the forward region (a rapidity gap). Presented studies of energy deposited in forward part of calorimeter by various types of events yield two rapidity gap definitions. Both of them use a fixed rapidity interval in calorimeter |η| ϵ [2.6,5.2] and introduce an upper limit on the energy deposited in this region. First definition, which corresponds to the lowest systematical errors, uses a limit of 10 GeV, an energy limit in the second definition is set to 3 GeV. This alternative definition corresponds to the lowest contamination of diffractive sample by non-diffractive events, on the other hand it is accompanied with rejection of high percentage of diffractive candidates. Using the gap definition dijet diffractive data are then selected and compared to inclusive dijet events in various distributions. The main focus is to measure the difference in azimuthal angles between two leading jets in events with at least two high pt central jets. This variable is sensitive to the dynamics of the process. Indeed, the results show the different behavior of ΔΦ distributions between the inclusive and diffractive samples. It is also shown that this difference is bigger for lower pT jets. Other distributions presented in the thesis show that most

  12. Self-generated magnetic fields in blast-wave driven Rayleigh-Taylor experiments

    NASA Astrophysics Data System (ADS)

    Flaig, Markus; Plewa, Tomasz

    2015-12-01

    We study the effect of self-generated magnetic fields in two-dimensional computer models of blast-wave driven high-energy density Rayleigh-Taylor instability (RTI) experiments. Previous works [1,2] suggested that such fields have the potential to influence the RTI morphology and mixing. When neglecting the friction force between electrons and ions, we do indeed find that dynamically important (β≲103) magnetic fields are generated. However, in the more realistic case where the friction force is accounted for, the resulting fields are much weaker, β≳105 , and can no longer influence the dynamics of the system. Although we find no evidence for dynamically important magnetic fields being created in the two-dimensional case studied here, the situation might be different in a three-dimensional setup, which will be addressed in a future study.

  13. Flow dynamics and magnetic induction in the von-Kármán plasma experiment

    NASA Astrophysics Data System (ADS)

    Plihon, N.; Bousselin, G.; Palermo, F.; Morales, J.; Bos, W. J. T.; Godeferd, F.; Bourgoin, M.; Pinton, J.-F.; Moulin, M.; Aanesland, A.

    2015-01-01

    The von-Kármán plasma experiment is a novel versatile experimental device designed to explore the dynamics of basic magnetic induction processes and the dynamics of flows driven in weakly magnetized plasmas. A high-density plasma column (1016-1019 particles. m-3) is created by two radio-frequency plasma sources located at each end of a 1 m long linear device. Flows are driven through J × B azimuthal torques created from independently controlled emissive cathodes. The device has been designed such that magnetic induction processes and turbulent plasma dynamics can be studied from a variety of time-averaged axisymmetric flows in a cylinder. MHD simulations implementing volume-penalization support the experimental development to design the most efficient flow-driving schemes and understand the flow dynamics. Preliminary experimental results show that a rotating motion of up to nearly 1 km/s is controlled by the J × B azimuthal torque.

  14. Effects of resistive magnetic field on fast electron divergence measured in experiments

    NASA Astrophysics Data System (ADS)

    Yang, X. H.; Zhuo, H. B.; Ma, Y. Y.; Xu, H.; Yu, T. P.; Zou, D. B.; Ge, Z. Y.; Xu, B. B.; Zhu, Q. J.; Shao, F. Q.; Borghesi, M.

    2015-02-01

    Transport of fast electrons driven by an ultraintense laser through a tracer layer buried in solid targets is studied by particle-in-cell simulations. It is found that intense resistive magnetic fields, having a magnitude of several thousand Tesla, are generated at the interfaces of the materials due to the steep resistivity gradient between the target and tracer layer. Such magnetic fields can significantly inhibit the fast electron propagation. The electrons that can penetrate the first interface are mostly confined in the buried layer by the magnetic fields and cause heating of the tracer layer. The lateral extent of the heated region can be significantly larger than that of the relativistic electron beam. This finding suggests that the relativistic electron divergence inferred from Kα x-ray emission in experiments might be overestimated.

  15. Crucial Experiments in Quantum Physics.

    ERIC Educational Resources Information Center

    Trigg, George L.

    The six experiments included in this monography are titled Blackbody Radiation, Collision of Electrons with Atoms, The Photoelectric Effect, Magnetic Properties of Atoms, The Scattering of X-Rays, and Diffraction of Electrons by a Crystal Lattice. The discussion provides historical background by giving description of the original experiments and…

  16. High-pressure neutron diffraction

    SciTech Connect

    Xu, Hongwu

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  18. Crystal structure and magnetic properties of Bi{sub 0.8}A{sub 0.2}FeO{sub 3} (A = La, Ca, Sr, Ba) multiferroics using neutron diffraction and Mossbauer spectroscopy

    SciTech Connect

    Rangi, Manisha; Agarwal, Ashish Sanghi, Sujata; Singh, Ripandeep; Meena, S. S.; Das, A.

    2014-08-15

    Bi{sub 0.8}A{sub 0.2}FeO{sub 3} (A = La, Ca, Sr, Ba) multiferroics were studied using x-ray, neutron diffraction and magnetization techniques. All the samples crystallized in rhombohedral structure with space group R3c. The compounds exhibit antiferromagnetic (AFM) ordering at 300 K and no evidence of further structural or magnetic transition was observed on lowering of temperature below it. The magnetic structure of these substituted compounds are found to be collinear G-type AFM structure as against the non collinear incommensurate magnetic structure reported in the case of parent compound. The moments on Fe at 6 K are aligned along the a-axis in the case of Ca-doped sample. With increase in the ionic radii of dopant, the moments are found to be aligned in the ac plane and the angle of tilt away from the a-axis increases. The observed change in the magnetic structure with substitution is attributed to the intrinsic structural distortion as evidenced by the change in the bond angle (Fe-O-Fe) and bond distances (Bi-O, Fe-O). It has been found that heterovalent substitution A{sup 2+} results in the formation of oxygen vacancies in the parent lattices as the possibility of Fe{sup 4+} ruled out by Mössbauer spectra recorded at room temperature. Higher value of remnant magnetization (0.4187 emu/g) and coercivity (4.7554kOe) is observed in Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3} sample in comparison to other substituted samples revealing a strong correlation between ionic radii and magnetization.

  19. Distinguishing the Magnetorotational Instability (MRI) from Magnetized Ekman Flows in the PPPL MRI Experiment

    NASA Astrophysics Data System (ADS)

    Gilson, Erik; Caspary, Kyle; Goodman, Jeremy; Ji, Hantao; Schartman, Ethan; Wei, Xing

    2015-11-01

    Results are presented from initial experiments on the upgraded Magnetorotational Instability (MRI) experiment that uses GaInSn as the working fluid and now operates with conductive end caps to improve the coupling of angular momentum to the fluid to increase the saturation amplitude of the MRI signal. Measurements of the fluid velocity field and perturbed magnetic field over a range of magnetic Reynolds numbers, Rm , and Lundquist numbers, S, are compared with results from the SFEMaNS code in order to separate the effects of MRI on the system from effects such as Ekman flows and Shercliff layer instabilities. The MRI can be identified by observing its growth rate, noting the relative magnitudes and spatial distributions of the perturbed radial flow velocity ur and radial magnetic field Br, and measuring the scaling of ur and Br with Rm . The clear identification of the onset of MRI in the apparatus is complicated by the geometry and boundary conditions creating an imperfect supercritical pitchfork bifurcation. Nevertheless, a stability diagram can be created that shows that MRI is a weak-field instability that occurs only below a certain value of the normalized magnetic field S / Rm but above a threshold where viscous effects damps the growth of the instability.

  20. E906 Experiment: Study of Background Rates with a Solid Magnet

    NASA Astrophysics Data System (ADS)

    Akinbule, Obiageli

    2008-10-01

    Fermilab (Fermi National Accelerator Laboratory) E906 is an experiment to determine the ratio of d-bar to u-bar quarks in the nucleon sea. The experiment measures the di-muon pairs that are produced via the Drell-Yan process, which is when a quark and anti-quark annihilate, creating a di-lepton pair. With a goal of extending the E866/NuSea measurements to higher Bjorken x, it will help reveal the structure of the proton. The results to be presented focus on using GEANT4 Monte Carlo simulations to investigate spectrometer acceptance and background rates if a solid iron magnet is used, as opposed to the original plan of an open magnet filled with hadron absorbers. A solid iron magnet would be relatively low cost, since the coils and iron can be taken from parts of the E866/NuSea detector apparatus. Results of these simulations will be shown to demonstrate that the solid iron magnet will give acceptable results. Results will also be shown on ideas to reduce the background from in-flight pion decays from the liquid hydrogen and deuterium targets.

  1. Magnetic and Langmuir Probe Measurements on the Plasmoid Thruster Experiment (PTX)

    NASA Technical Reports Server (NTRS)

    Koelfgen, Syri J.; Eskridge, Richard; Lee, Michael H.; Martin, Adam; Hawk, Clark W.; Fimognan, Peter

    2004-01-01

    The Plasmoid Thruster Experiment (PTX) operates by inductively producing plasmoids in a conical theta-pinch coil and ejecting them at high velocity. A plasmoid is a plasma with an imbedded closed magnetic field structure. The shape and magnetic field structure of the translating plasmoids have been measured with of an array of magnetic field probes. Six sets of two B-dot probes were constructed for measuring B(sub z) and B(sub theta), the axial and azimuthal components of the magnetic field. The probes are wound on a square G10 form, and have an average (calibrated) NA of 9.37 x l0(exp -5) square meters, where N is the number of turns and A is the cross-sectional area. The probes were calibrated with a Helmholtz coil, driven by a high-voltage pulser to measure NA, and by a signal generator to determine the probe's frequency response. The plasmoid electron number density n(sub e) electron temperature T(sub e), and velocity ratio v/c(sub m), (where v is the bulk plasma flow velocity and c(sub m), is the ion thermal speed) have also been measured with a quadruple Langmuir probe. The Langmuir probe tips are 10 mm long, 20-mil diameter stainless steel wire, housed in a 6-inch long 4-bore aluminum rod. Measurements on PTX with argon and hydrogen from the magnetic field probes and quadruple Langmuir probe will be presented in this paper.

  2. Hall Reconnection in Partially Ionized Plasmas in the Magnetic Reconnection Experiment

    NASA Astrophysics Data System (ADS)

    Lawrence, Eric; Ji, Hantao; Yamada, Masaaki; Yoo, Jongsoo

    2011-10-01

    In many space and astrophysical plasmas, such as the solar chromosphere and protoplanetary disks, the degree of ionization can be quite low; often 1% or less. In addition, magnetic reconnection is thought to be a fundamental process in these plasmas. The presence of a large neutral atom population has at least two effects relevant to magnetic reconnection. First, electron-neutral collisions enhance resistive dissipation. Second, strong ion-neutral collisions increase effective ion inertia. This may increase the length scales on which fast Hall reconnection is predicted to occur. By using high gas fill pressures in the Magnetic Reconnection Experiment (MRX), we can study reconnection in partially or weakly ionized plasmas (nn /ne = 1 - - 200). A newly constructed magnetic probe array allows us to make magnetic measurements of the reconnection region with high spatial resolution and large spatial extent. This will allow us to diagnose, for example, the structure of the Hall quadrupole field in these conditions. Langmuir and spectroscopic diagnostics will also provide insight into how neutrals affect the reconnection process. These results will also be discussed in the context of ongoing theoretical work.

  3. Versatile controllability of non-axisymmetric magnetic perturbations in KSTAR experiments

    NASA Astrophysics Data System (ADS)

    Han, Hyunsun; Jeon, Y. M.; in, Y.; Kim, J.; Yoon, S. W.; Hahn, S. H.; Ahn, H. S.; Woo, M. H.; Park, B. H.; Bak, J. G.; Kstar Team

    2015-11-01

    A newly upgraded IVCC (In-Vessel Control Coil) system equipped with four broadband power supplies, along with current connection patch panel, will be presented and discussed in terms of its capability on various KSTAR experiments. Until the last run-campaign, there were impressive experimental results on ELM(Edge Localized Mode) control experiments using the 3D magnetic field, but the non-axisymmetric field configuration could not be changed in a shot, let alone the limited number of accessible configurations. Introducing the new power supplies, such restrictions have been greatly reduced. Based on the preliminary commissioning results for 2015 KSTAR run-campaign, this new system has been confirmed to easily cope with various dynamic demands for toroidal and poloidal phases of 3D magnetic field in a shot. This enables us to diagnose the plasma response in more detail and to address the 3-D field impacts on the ELM behaviors better than ever.

  4. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    NASA Astrophysics Data System (ADS)

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Cooper, G. W.; Gomez, M. R.; Slutz, S.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Harding, E.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Torres, J. A.; Bur, J. A.; Cuneo, M. E.; Glebov, V. Yu; Harvey-Thompson, A. J.; Herrman, M. C.; Hess, M. H.; Johns, O.; Jones, B.; Lamppa, D. C.; Lash, J. S.; Martin, M. R.; McBride, R. D.; Peterson, K. J.; Porter, J. L.; Reneker, J.; Robertson, G. K.; Rochau, G. A.; Savage, M. E.; Smith, I. C.; Styron, J. D.; Vesey, R. A.

    2016-05-01

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ∼2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner∼1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Plans to improve and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.

  5. Oil Spill Remediation Using Magnetic Particles: An Experiment in Environmental Technology

    NASA Astrophysics Data System (ADS)

    Orbell, John D.; Godhino, Leroy; Bigger, Stephen W.; Nguyen, Thi Man; Ngeh, Lawrence N.

    1997-12-01

    A simple experiment is described in which the potential of commercially available steel pellets coated with polyethylene (PE) or poly(vinylchloride) (PVC) to remediate an oil spill is demonstrated. Polymer-coated particles are weighed, immersed in oil, magnetically harvested and the remaining oil is weighed in order to enable students to quantitatively investigate the adsorption process. The possibility of recycling the beads and reclaiming the oil is also demonstrated.

  6. Physics of forced magnetic reconnection in coaxial helicity injection experiments in National Spherical Torus Experimenta)

    NASA Astrophysics Data System (ADS)

    Ebrahimi, F.; Raman, R.; Hooper, E. B.; Sovinec, C. R.; Bhattacharjee, A.

    2014-05-01

    We numerically examine the physics of fast flux closure in transient coaxial helicity injection (CHI) experiments in National Spherical Torus Experiment (NSTX). By performing resistive Magnetohydrodynamics (MHD) simulations with poloidal injector coil currents held constant in time, we find that closed flux surfaces are formed through forced magnetic reconnection. Through a local Sweet-Parker type reconnection with an elongated current sheet in the injector region, closed flux surfaces expand in the NSTX global domain. Simulations demonstrate outflows approaching poloidally Alfvénic flows and reconnection times consistent with the Sweet-Parker model. Critical requirements for magnetic reconnection and flux closure are studied in detail. These primary effects, which are magnetic diffusivity, injector flux, injector flux footprint width, and rate of injector voltage reduction, are simulated for transient CHI experiments. The relevant time scales for effective reconnection are τV<τrec≈τA√S (1+Pm)1/4<τR, where τV is the time for the injector voltage reduction, τA is the poloidal Alfvén transit time, τR is the global resistive diffusion time, and Pm and S are Prandtl and Lundquist numbers.

  7. High Power Heating of Magnetic Reconnection in UTokyo Spherical Tokamak Merging Experiment: TS-U

    NASA Astrophysics Data System (ADS)

    Ono, Y.; Kawanami, M.; Kimura, K.; Nakai, R.; Nishida, K.; Ishida, R.; Yamanaka, H.; Kuwahata, A.; Tanabe, H.; Inomoto, M.; Cheng, C. Z.; TS; UTST Team

    2015-11-01

    Significant ion heating of magnetic reconnection up to 0.2keV and 1.2keV were documented in two tokamak merging experiments: TS-3 and MAST, leading us to a new high-field merging experiment: TS-U in University of Tokyo. 1D and 2D contours of ion and electron temperatures measured in TS-3 already revealed clear energy-conversion of magnetic reconnection: huge outflow heating of ions in the downstream and electron heating localized at the X-point. It is noted that the ion heating energy is proportional to square of the reconnecting (poloidal) magnetic field Brec. It is because the reconnection outflow accelerates ions up to the poloidal Alfven speed. The accelerated ions are thermalized by shock-like density pileups in the downstreams. These results agree qualitatively with recent solar satellite observations and PIC simulation results. Based on those results, our poster will show the design of upscaled high-field tokamak merging experiment: TS-U. The high-power heating of tokamak merging is useful not only for laboratory study of reconnection heating mechanisms but also for economical startup and heating of tokamak plasmas. The tokamak merging with Brec>0.3T will enables us to heat the tokamak plasma to the burning regime: Ti>5keV without using any additional heating facility.

  8. FLASH hydrodynamic simulations of experiments to explore the generation of cosmological magnetic fields

    NASA Astrophysics Data System (ADS)

    Scopatz, A.; Fatenejad, M.; Flocke, N.; Gregori, G.; Koenig, M.; Lamb, D. Q.; Lee, D.; Meinecke, J.; Ravasio, A.; Tzeferacos, P.; Weide, K.; Yurchak, R.

    2013-03-01

    We report the results of FLASH hydrodynamic simulations of the experiments conducted by the University of Oxford High Energy Density Laboratory Astrophysics group and its collaborators at the Laboratoire pour l'Utilisation de Lasers Intenses (LULI). In these experiments, a long-pulse laser illuminates a target in a chamber filled with Argon gas, producing shock waves that generate magnetic fields via the Biermann battery mechanism. The simulations show that the result of the laser illuminating the target is a series of complex hydrodynamic phenomena.

  9. Endstation for ultrafast magnetic scattering experiments at the free-electron laser in Hamburg

    SciTech Connect

    Mueller, L.; Gutt, C.; Streit-Nierobisch, S.; Walther, M.; Gruebel, G.; Schaffert, S.; Pfau, B.; Flewett, S.; Geilhufe, J.; Eisebitt, S.; Buettner, F.; Guenther, C. M.; Kobs, A.; Hille, M.; Stickler, D.; Froemter, R.; Oepen, H. P.; Luening, J.

    2013-01-15

    An endstation for pump-probe small-angle X-ray scattering (SAXS) experiments at the free-electron laser in Hamburg (FLASH) is presented. The endstation houses a solid-state absorber, optical incoupling for pump-probe experiments, time zero measurement, sample chamber, and detection unit. It can be used at all FLASH beamlines in the whole photon energy range offered by FLASH. The capabilities of the setup are demonstrated by showing the results of resonant magnetic SAXS measurements on cobalt-platinum multilayer samples grown on freestanding Si{sub 3}N{sub 4} membranes and pump-laser-induced grid structures in multilayer samples.

  10. High sensitivity nuclear magnetic resonance probe for anvil cell pressure experiments.

    PubMed

    Haase, Jürgen; Goh, Swee K; Meissner, Thomas; Alireza, Patricia L; Rybicki, Damian

    2009-07-01

    While the highest pressures can be achieved with diamond anvil cells, limited sample size and anvil geometry have hampered their application in nuclear magnetic resonance (NMR) experiments due to weak signal-to-noise. Here we report a new probe design that is based on having the resonant radio frequency coil that encloses the sample within the anvil cell inside the gasket hole. This increases the filling factor tremendously and results in greatly enhanced NMR sensitivity. The setup is described together with room temperature Na and Al NMR experiments. PMID:19655963

  11. The Operation of Magnetically Assisted Fluidized Bed in Microgravity and Variable Gravity: Experiment and Theory

    NASA Astrophysics Data System (ADS)

    Sornchamni, T.; Jovanovic, G.; Atwater, J.; Akse, J.; Wheeler, R.

    Typically, the operation of a conventional fluidized bed relies on the balance of gravitational, buoyancy, and drag forces. In the absence of normal gravity, or under microgravity and variable gravity conditions, the gravitational force must be replaced with an alternative force to restore fluidization. Our work has shown that, given a suitable variable magnetic field design, the resulting magnetic field gradient can create sufficient magnetic force acting upon the ferromagnetic particles to replace or supplement the gravitational force. Therefore, the ferromagnetic granular media can be fluidized in either microgravity or hypogravity. In this paper, we present our experimental and theoretical work leading to a) development of theoretical model based on fundamental principles for the design of the Gradient Magnetically Assisted Fluidized Bed (G-MAFB), and b) practical implementation of the G-MAFB in the filtration and destruction of solid biowaste particles from liquid streams. The G-MAFB system consists of a fluidization column and series of Helmholtz electromagnetic coils, with DC power supply. Each Helmholtz ring is powered and controlled separately. Experiments are performed in both 0g (on board NASA KC- 135) and 1g (laboratory) environments. The experiments in 0g are conducted in a two-dimensional, square cross-section, tapered fluidization column. The tapered shape is introduced to provide additional stability to the fluidization particles. The experiments in 0g prove that the magnetic force has a significant role in keeping the particles from extruding out of the bed. Without the magnetic force, it is impossible to have fluidization in space. Solid waste destruction technologies are needed to support long duration human habitation in space. The current technologies, including supercritical water oxidation (SCWO), microwave powered combustion and fluidized bed incineration, have been applied to the destruction of solid wastes, but none are compatible with

  12. The role of large eddy fluctuations in the magnetic dynamics of the Madison Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Kaplan, Elliot

    The Madison Dynamo Experiment (MDE), a liquid sodium magnetohydrodynamics experiment in a 1 m diameter sphere at the University of Wisconsin-Madison, had measured [in Spence et al., 2006] diamagnetic electrical currents in the experiment that violated an anti dynamo theorem for axisymmetric flow. The diamagnetic currents were instead attributed to nonaxisymmetric turbulent fluctuations. The experimental apparatus has been modified to reduce the strength of the large-scale turbulence driven by the shear layer in its flow. A 7.62 cm baffle was affixed to the equator of the machine to stabilize the shear layer. This reduction has correlated with a decrease in the magnetic fields, induced by the flow, which had been associated with the α and β effects of mean-field magnetohydrodynamics. The research presented herein presents the experimental evidence for reduced fluctuations and reduced mean field emfs, and provides a theoretical framework—based upon mean-field MHD—that connects the observations. The shapes of the large-scale velocity fluctuations are inferred by the spectra of induced magnetic fluctuations and measured in a kinematically similar water experiment. The Bullard and Gellman [1954] formalism demonstrates that the large-scale velocity fluctuations that are inhibited by the baffle can beat with the large-scale magnetic fluctuations that they produce to generate a mean-field emf of the sort measured in Spence et al. [2006]. This shows that the reduction of these large-scale eddies has brought the MDE closer to exciting a dynamo magnetic field. We also examine the mean-field like effects of large-scale (stable) eddies in the Dudley-James [1989] two-vortex dynamo (that the MDE was based upon). Rotating the axis of symmetry redefines the problem from one of an axisymmetric flow exciting a nonaxisymmetric field to one of a combination of axisymmetric and nonaxisymmetric flows exciting a predominantly axisymmetric magnetic

  13. Photoinduced diffraction in polymer waveguides.

    PubMed

    Andrews, J H; Singer, K D

    1993-11-20

    We report on techniques for measuring photoinduced diffraction in prism-coupled slab polymer waveguides. Diffraction effects resulting from photochromic gratings in slab waveguides of Disperse Red 1 dye in polymethylmethacrylate were studied. Optical damage in the form of diffractive mode conversion was observed when we coupled in light with a wavelength slightly longer than the absorption edge of Disperse Red 1 dye. Slowly growing satellite beams in the outcoupled light were attributed to anisotropic scattering between the lowest-order TE mode and the lowest-order TM mode caused by self-diffraction from a grating produced through the photochromic effect. We have also investigated the effect of mode-coupling changes on the determination of diffraction efficiency and sensitivity in waveguide experiments. Diffraction efficiencies predicted by measurements of the modulation depth in the guide are found to overstate the actual diffraction efficiencies that could be observed in this geometry. Techniques for overc ming this limitation and for improving estimates of the energy density and interaction length in the guide are noted.

  14. High-temperature X-ray diffraction measurements of fluorite-related rare earth antimonates Ln{sub 3}SbO{sub 7} (Ln=Nd, Tb) and their magnetic properties

    SciTech Connect

    Hinatsu, Yukio Doi, Yoshihiro

    2014-09-15

    Ternary rare-earth antimonates Ln{sub 3}SbO{sub 7} (Ln=rare earths) were prepared, and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln=La, Pr; Ccmm for Ln=Sm–Dy), in which Ln{sup 3+} ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated). For Ln=Nd, two phases with the Cmcm and Ccmm space groups coexist at room temperature. When the temperature was increased, the Nd{sub 3}SbO{sub 7} compound transformed into a single phase with the space group Cmcm. Through magnetic susceptibility measurements, an antiferromagnetic transition was observed at 3.0 K (Ln=Nd) and 7.8 K (Ln=Tb). Analysis of the magnetic specific heat for Tb{sub 3}SbO{sub 7} indicates that the 8-coordinated Tb ions magnetically orders at 7.8 K, and with furthermore decreasing temperature, the 7-coordinated Tb ions shows antiferromagnetic ordering at 3.0 K. - Graphical abstract: Temperature dependence of the specific heat divided by temperature (C{sub p}/T) and the magnetic entropy (S{sub mag}) for Tb{sub 3}SbO{sub 7}. Two-step magnetic transition has been observed. - Highlights: • The phase transition of Nd{sub 3}SbO{sub 7} is from the Ccmm space group to the Cmcm one. • Nd{sub 3}SbO{sub 7} shows an antiferromagnetic transition at 3.0 K. • For Tb{sub 3}SbO{sub 7}, two-step magnetic transition has been observed at 7.8 and 3.0 K.

  15. Single Photon diffraction and interference

    NASA Astrophysics Data System (ADS)

    Hodge, John

    2015-04-01

    A previous paper based on the Scalar Theory of Everything studied photon diffraction and interference (IntellectualArchive, Vol.1, No. 3, P. 20, Toronto, Canada July 2012. http://intellectualarchive.com/?link=item&id=597). Several photons were required in the experiment at the same time. Interference experiments with one photon in the experiment at a time also showed interference patterns. The previous paper with the Bohm Interpretation, models of the screen and mask, and the Transaction Interpretation of Quantum Mechanics were combined. The reverse wave required by the Transaction Interpretation was provided by a reflected plenum wave rather than a reverse time wave. The speed of the plenum wave was assumed to be much faster than the speed of photons/light. Using the assumptions of Fraunhofer diffraction resulted in the same equation for the photon distribution on a screen as the intensity pattern of the Fraunhofer diffraction. (http://myplace.frontier.com/ ~ jchodge/)

  16. Numerical Experiments on the Two-step Emergence of Twisted Magnetic Flux Tubes in the Sun

    NASA Astrophysics Data System (ADS)

    Toriumi, S.; Yokoyama, T.

    2011-07-01

    We present the new results of the two-dimensional numerical experiments on the cross-sectional evolution of a twisted magnetic flux tube rising from the deeper solar convection zone (-20,000 km) to the corona through the surface. The initial depth is 10 times deeper than most of the previous calculations focusing on the flux emergence from the uppermost convection zone. We find that the evolution is illustrated by the following two-step process. The initial tube rises due to its buoyancy, subject to aerodynamic drag due to the external flow. Because of the azimuthal component of the magnetic field, the tube maintains its coherency and does not deform to become a vortex roll pair. When the flux tube approaches the photosphere and expands sufficiently, the plasma on the rising tube accumulates to suppress the tube's emergence. Therefore, the flux decelerates and extends horizontally beneath the surface. This new finding owes to our large-scale simulation, which simultaneously calculates the dynamics within the interior as well as above the surface. As the magnetic pressure gradient increases around the surface, magnetic buoyancy instability is triggered locally and, as a result, the flux rises further into the solar corona. We also find that the deceleration occurs at a higher altitude than assumed in our previous experiment using magnetic flux sheets. By conducting parametric studies, we investigate the conditions for the two-step emergence of the rising flux tube: field strength >~ 1.5 × 104 G and the twist >~ 5.0 × 10-4 km-1 at -20,000 km depth.

  17. NUMERICAL EXPERIMENTS ON THE TWO-STEP EMERGENCE OF TWISTED MAGNETIC FLUX TUBES IN THE SUN

    SciTech Connect

    Toriumi, S.; Yokoyama, T.

    2011-07-10

    We present the new results of the two-dimensional numerical experiments on the cross-sectional evolution of a twisted magnetic flux tube rising from the deeper solar convection zone (-20,000 km) to the corona through the surface. The initial depth is 10 times deeper than most of the previous calculations focusing on the flux emergence from the uppermost convection zone. We find that the evolution is illustrated by the following two-step process. The initial tube rises due to its buoyancy, subject to aerodynamic drag due to the external flow. Because of the azimuthal component of the magnetic field, the tube maintains its coherency and does not deform to become a vortex roll pair. When the flux tube approaches the photosphere and expands sufficiently, the plasma on the rising tube accumulates to suppress the tube's emergence. Therefore, the flux decelerates and extends horizontally beneath the surface. This new finding owes to our large-scale simulation, which simultaneously calculates the dynamics within the interior as well as above the surface. As the magnetic pressure gradient increases around the surface, magnetic buoyancy instability is triggered locally and, as a result, the flux rises further into the solar corona. We also find that the deceleration occurs at a higher altitude than assumed in our previous experiment using magnetic flux sheets. By conducting parametric studies, we investigate the conditions for the two-step emergence of the rising flux tube: field strength {approx}> 1.5 x 10{sup 4} G and the twist {approx}> 5.0 x 10{sup -4} km{sup -1} at -20,000 km depth.

  18. Zonal shear and super-rotation in a magnetized spherical Couette flow experiment

    NASA Astrophysics Data System (ADS)

    Brito, D.; Alboussière, T.; Cardin, P.; Gagnière, N.; Jault, D.; La Rizza, P.; Masson, J.; Nataf, H.; Schmitt, D.

    2011-12-01

    We present measurements performed in a spherical shell filled with liquid sodium, where a 74 mm-radius inner sphere is rotated while a 210 mm-radius outer sphere is at rest. The inner sphere holds a dipolar magnetic field and acts as a magnetic propeller when rotated. In this experimental set-up called DTS, direct measurements of the velocity are performed by ultrasonic Doppler velocimetry. Differences in electric potential and the induced magnetic field are also measured to characterize the magnetohydrodynamic flow. Rotation frequencies of the inner sphere are varied between -30 Hz and +30 Hz, the magnetic Reynolds number based on measured sodium velocities and on the shell radius reaching to about 33. We have investigated the mean axisymmetric part of the flow, which consists of differential rotation. Strong super-rotation of the fluid with respect to the rotating inner sphere is directly measured. It is found that the organization of the mean flow does not change much throughout the entire range of parameters covered by our experiment. The direct measurements of zonal velocity give a nice illustration of Ferraro's law of isorotation in the vicinity of the inner sphere where magnetic forces dominate inertial ones. The transition from a Ferraro regime in the interior to a geostrophic regime, where inertial forces predominate, in the outer regions has been well documented. It takes place where the local Elsasser number is about 1. A quantitative agreement with non-linear numerical simulations is obtained when keeping the same Elsasser number. The experiments also reveal a region that violates Ferraro's law just above the inner sphere.

  19. Cryogenic Considerations for Superconducting Magnet Design for the Material Plasma Exposure eXperiment

    SciTech Connect

    Duckworth, Robert C; Demko, Dr. Jonathan A; Lumsdaine, Arnold; Caughman, John B; Goulding, Richard Howell; McGinnis, William Dean; Bjorholm, Thomas P; Rapp, Juergen

    2015-01-01

    In order to determine long term performance of plasma facing components such as diverters and first walls for fusion devices, next generation plasma generators are needed. A Material Plasma Exposure eXperiment (MPEX) has been proposed to address this need through the generation of plasmas in front of the target with electron temperatures of 1-15 eV and electron densities of 1020 to 1021 m-3. Heat fluxes on target diverters could reach 20 MW/m2. In order generate this plasma, a unique radio frequency helicon source and heating of electrons and ions through Electron Bernstein Wave (EBW) and Ion Cyclotron Resonance Heating (ICRH) has been proposed. MPEX requires a series of magnets with non-uniform central fields up to 2 T over a 5m length in the heating and transport region and 1 T uniform central field over a 1-m length on a diameter of 1.3 m. Given the field requirements, superconducting magnets are under consideration for MPEX. In order to determine the best construction method for the magnets, the cryogenic refrigeration has been analyzed with respect to cooldown and operational performance criteria for open-cycle and closed-cycle systems, capital and operating costs of these system, and maturity of supporting technology such as cryocoolers. These systems will be compared within the context of commercially available magnet constructions to determine the most economical method for MPEX operation. The current state of the MPEX magnet design including details on possible superconducting magnet configurations will be presented.

  20. Morphology and magnetism of multifunctional nanostructured γ-Fe2O3 films: Simulation and experiments

    NASA Astrophysics Data System (ADS)

    Neumann, R. F.; Bahiana, M.; Paterno, L. G.; Soler, M. A. G.; Sinnecker, J. P.; Wen, J. G.; Morais, P. C.

    2013-12-01

    This paper introduces a new approach for simulating magnetic properties of nanocomposites comprising magnetic particles embedded in a non-magnetic matrix, taking into account the 3D structure of the system in which particles’ positions correctly mimic real samples. The proposed approach develops a multistage simulation procedure in which the size and distribution of particles within the host matrix is firstly attained by means of the Cell Dynamic System (CDS) model. The 3D structure provided by the CDS step is further employed in a Monte Carlo (MC) simulation of zero-field-cooled/field-cooled (ZFC/FC) and magnetic hysteresis loops (M×H curves) for the system. Simulations are aimed to draw a realistic picture of the as-produced ultra-thin films comprising maghemite nanoparticles dispersed in polyaniline. Comparison (ZFC/FC and M×H curves) between experiments and simulations regarding the maximum of the ZFC curve (TMAX), remanence (MR/Ms) and coercivity (HC) revealed the accuracy of the multistage approach proposed here while providing information about the system's morphology and magnetic properties. For a typical sample the value we found experimentally for TMAX (54 K) was very close to the value provided by the simulation (53 K). For the parameters depending on the nanoparticle clustering the experimental values were consistently lower (MR/Ms=0.32 and HC=210 Oe) than the values we found in the simulation (MR/Ms=0.53 and HC=274 Oe). Indeed, the approach introduced here is very promising for the design of real magnetic nanocomposite samples with optimized features.

  1. Cryogenic considerations for superconducting magnet design for the material plasma exposure experiment

    NASA Astrophysics Data System (ADS)

    Duckworth, R. C.; Demko, J. A.; Lumsdaine, A.; Rapp, J.; Bjorholm, T.; Goulding, R. H.; Caughman, J. B. O.; McGinnis, W. D.

    2015-12-01

    In order to determine long term performance of plasma facing components such as diverters and first walls for fusion devices, next generation plasma generators are needed. A Material Plasma Exposure eXperiment (MPEX) has been proposed to address this need through the generation of plasmas in front of the target with electron temperatures of 1-15 eV and electron densities of 1020 to 1021 m-3. Heat fluxes on target diverters could reach 20 MW/m2. To generate this plasma, a unique radio frequency helicon source and heating of electrons and ions through Electron Bernstein Wave (EBW) and Ion Cyclotron Resonance Heating (ICRH) has been proposed. MPEX requires a series of magnets with non-uniform central fields up to 2 T over a 5-m length in the heating and transport region and 1 T uniform central field over a 1-m length on a diameter of 1.3 m. Given the field requirements, superconducting magnets are under consideration for MPEX. In order to determine the best construction method for the magnets, the cryogenic refrigeration has been analyzed with respect to cooldown and operational performance criteria for open-cycle and closed-cycle systems, capital and operating costs of these system, and maturity of supporting technology such as cryocoolers. These systems will be compared within the context of commercially available magnet constructions to determine the most economical method for MPEX operation. The current state of the MPEX magnet design including details on possible superconducting magnet configurations is presented.

  2. Femtosecond single-electron diffraction

    PubMed Central

    Lahme, S.; Kealhofer, C.; Krausz, F.; Baum, P.

    2014-01-01

    Ultrafast electron diffraction allows the tracking of atomic motion in real time, but space charge effects within dense electron packets are a problem for temporal resolution. Here, we report on time-resolved pump-probe diffraction using femtosecond single-electron pulses that are free from intra-pulse Coulomb interactions over the entire trajectory from the source to the detector. Sufficient average electron current is achieved at repetition rates of hundreds of kHz. Thermal load on the sample is avoided by minimizing the pump-probe area and by maximizing heat diffusion. Time-resolved diffraction from fibrous graphite polycrystals reveals coherent acoustic phonons in a nanometer-thick grain ensemble with a signal-to-noise level comparable to conventional multi-electron experiments. These results demonstrate the feasibility of pump-probe diffraction in the single-electron regime, where simulations indicate compressibility of the pulses down to few-femtosecond and attosecond duration. PMID:26798778

  3. An Update on Results from the Magnetic Properties Experiments on the Mars Exploration Rovers, Spirit and Opportunity

    NASA Technical Reports Server (NTRS)

    Madsen, M. B.; Arneson, H. M.; Bertelsen, P.; Bell, J. F., III; Binau, C. S.; Gellert, R.; Goetz, W.; Gunnlaugsson, H. P.; Herkenhoff, K. E.; Hviid, S. F.

    2005-01-01

    The Magnetic Properties Experiments were designed to investigate the properties of the airborne dust in the Martian atmosphere. A preferred interpretation of previous experiments (Viking and Pathfinder) was that the airborne dust is primarily composed by composite silicate particles containing as a minor constituent the mineral maghemite (gamma-Fe2O3). In this abstract we show how the magnetic properties experiments on Spirit and Opportunity provide information on the distribution of magnetic mineral(s) in the dust on Mars, with emphasis on results from Opportunity.

  4. Heat capacity and neutron diffraction studies on the frustrated magnetic Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution

    SciTech Connect

    Pedro, I. de; Rojo, J.M.; Rodriguez Fernandez, J.; Sanchez Marcos, J.; Fernandez-Diaz, M.T.; Rojo, T.

    2012-04-15

    The Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1] solid solution exhibits a complex magnetic behaviour due to the bond-frustration in its magnetic structure. Heat capacity measurements of the (x=0.1-0.5) phases show a three-dimensional magnetic ordering ({lambda} anomaly) that shifts to lower temperatures and becomes broader as the AsO{sub 4}{sup 3-} content increases. For x=0.75, no significant feature was observed whereas for higher arsenate ion content, x=0.9 and 1, a small maximum was detected. The magnetic structures of solid solution are consistent with the existence of predominant antiferromagnetic superexchange interactions through the |OH| and |XO{sub 4}| (X=P and As) groups between the Co{sup +2} ions. The substitution of PO{sub 4}{sup 3-} by AsO{sub 4}{sup 3-} anions by more than 90% substantially modifies the magnetic exchange pathways in the solid solution, leading to an incommensurate antiferromagnetic structure in Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [x=0.9 and 1] phases. - Graphical abstract: Magnetic structures of Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} [0{<=}x{<=}1]. The ordering of the magnetic moments of Co{sup 2+} is in c direction for the two crystallographic positions (dimers and chains) in all compounds. The unit cell is surrounded by a red line. Highlights: Black-Right-Pointing-Pointer Synthesis of a new adamite-type compounds, Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} (0.1, 0.25, 0.5, 0.75, 0.9) phases. Black-Right-Pointing-Pointer Co{sub 2}(OH)(PO{sub 4}){sub 1-x}(AsO{sub 4}){sub x} (0-1) solid solution; magnetic frustrated system. Black-Right-Pointing-Pointer High resolution neutron powder diffraction to determine the crystal structures. Black-Right-Pointing-Pointer Incommensurate magnetic structures at low temperature. Black-Right-Pointing-Pointer Magnetostructural correlations in cobalt-based Co{sub 2}(OH)XO{sub 4} (X=P and As) insulation compounds.

  5. Industrial applications of neutron diffraction

    SciTech Connect

    Felcher, G.P.

    1989-01-01

    Neutron diffraction (or, to be more general, neutron scattering) is a most versatile and universal tool, which has been widely employed to probe the structure, the dynamics and the magnetism of condensed matter. Traditionally used for fundamental research in solid state physics, this technique more recently has been applied to problems of immediate industrial interest, as illustrated in examples covering the main fields of endeavour. 14 refs., 14 figs.

  6. Hydromagnetic Dynamics and Magnetic Field Enhancement in a Turbulent Spherical Couette Experiment

    NASA Astrophysics Data System (ADS)

    Stone, Douglas; Adams, Matthew; Kara, Onur; Lathrop, Daniel

    2015-11-01

    The University of Maryland Three Meter Geodynamo, a spherical Couette experiment filled with liquid sodium and geometrically similar to the earth's core, is used to study hydrodynamic and hydromagnetic phenomena in rapidly rotating turbulence. An external coil applies a magnetic field in order to study hydromagnetic effects relevant to the earth's outer core such as dynamo action, while an array of 31 external Hall sensors measures the Gauss coefficients of the resulting magnetic field. The flow state is strongly dependent on Rossby number, Ro = (ΩI -ΩO) /ΩO , where ΩI and ΩO are the inner and outer sphere rotation frequencies. The flow state is inferred from the torque required to drive the inner sphere. The generation of internal toroidal magnetic field through the Ω-effect is measured by a Hall probe inserted into the sodium. A self-sustaining dynamo has not yet been observed at rotation speeds up to ΩO=3 Hz, which is three-fourths of the design maximum of the experiment. However, continuous dipole amplification up to 12% of a small applied field has been observed at Ro=?17.7 while bursts of dipole field have been observed up to 15% of a large external applied field at Ro=+6.0 and up to 20% of a small applied field at Ro=+2.15.

  7. Results from colliding magnetized plasma jet experiments executed at the Trident laser facility

    NASA Astrophysics Data System (ADS)

    Manuel, M. J.-E.; Rasmus, A. M.; Kurnaz, C. C.; Klein, S. R.; Davis, J. S.; Drake, R. P.; Montgomery, D. S.; Hsu, S. C.; Adams, C. S.; Pollock, B. B.

    2015-11-01

    The interaction of high-velocity plasma flows in a background magnetic field has applications in pulsed-power and fusion schemes, as well as astrophysical environments, such as accretion systems and stellar mass ejections into the magnetosphere. Experiments recently executed at the Trident Laser Facility at the Los Alamos National Laboratory investigated the effects of an expanding aluminum plasma flow into a uniform 4.5-Tesla magnetic field created using a solenoid designed and manufactured at the University of Michigan. Opposing-target experiments demonstrate interesting collisional behavior between the two magnetized flows. Preliminary interferometry and Faraday rotation measurements will be presented and discussed. This work is funded by the U.S Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840. Support for this work was provided by NASA through Einstein Postdoctoral Fellowship grant number PF3-140111 awarded by the Chandra X-ray Center, which is operated by the Astrophysical Observatory for NASA under contract NAS8-03060.

  8. Laboratory Experiment of Magnetic Reconnection between Merging Flux Tubes with Strong Guide FIeld

    NASA Astrophysics Data System (ADS)

    Inomoto, M.; Kamio, S.; Kuwahata, A.; Ono, Y.

    2013-12-01

    Magnetic reconnection governs variety of energy release events in the universe, such as solar flares, geomagnetic substorms, and sawtooth crash in laboratory nuclear fusion experiments. Differently from the classical steady reconnection models, non-steady behavior of magnetic reconnection is often observed. In solar flares, intermittent enhancement of HXR emission is observed synchronously with multiple ejection of plammoids [1]. In laboratory reconnection experiments, the existence of the guide field, that is perpendicular to the reconnection field, makes significant changes on reconnection process. Generally the guide field will slow down the reconnection rate due to the increased magnetic pressure inside the current sheet. It also brings about asymmetric structure of the separatrices or effective particle acceleration in collisionless conditions. We have conducted laboratory experiments to study the behavior of the guide-field magnetic reconnection using plasma merging technique (push reconnection). Under substantial guide field even larger than the reconnection field, the reconnection generally exhibits non-steady feature which involves intermittent detachment of X-point and reconnection current center[2]. Transient enhancement of reconnection rate is observed simultaneously with the X-point motion[3]. We found two distinct phenomena associated with the guide-field non-steady reconnection. The one is the temporal and localized He II emission from X-point region, suggesting the production of energetic electrons which could excite the He ions in the vicinity of the X-point. The other is the excitation of large-amplitude electromagnetic waves which have similar properties with kinetic Alfven waves, whose amplitude show positive correlation with the enhancement of the reconnection electric field[4]. Electron beam instability caused by the energetic electrons accelerated to more than twice of the electron thermal velocity could be a potential driver of the

  9. Experiments on beam plasma interactions and EM waves in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Phelps, Alan D. R.

    2012-04-01

    An energetic electron beam can exhibit several types of interesting behaviour when interacting with plasmas and/or magnetic fields. The focus in the present work is on electron cyclotron maser interactions. The instabilities that occur are also often observed in space as well as in the laboratory. Some of the high power sources of electromagnetic radiation, such as gyrodevices, make use of similar instability mechanisms. Laboratory experiments and numerical simulations have led to both a better understanding of natural phenomena and the development of high power electromagnetic radiation sources for several applications in fusion plasma physics. The gyrotron is one such device that is being used to provide auxiliary heating for large tokamaks via electron cyclotron resonance heating (ECRH). It is planned to use a number of gyrotrons supplied by several nations in the ITER experiment. In the ITER experiment these gyrotrons will not only be used for auxiliary heating but also for advanced tailoring of the tokamak plasma properties.

  10. Description of the Large Gap Magnetic Suspension System (LGMSS) ground-based experiment

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J.

    1991-01-01

    A description of the Large Gap Magnetic Suspension System (LGMSS) ground-based experiment is presented. The LGMSS provides five degrees of freedom control of a cylindrical suspended element which is levitated above a floor-mounted array of air core electromagnets. The uncontrolled degree of freedom is rotation about the long axis of the cylinder (roll). Levitation and control forces are produced on a permanent magnet core which is embedded in the cylinder. The cylinder also contains light emitting diodes (LEDs), assorted electrons, and a power supply. The LEDs provide active targets for an optical position measurement system which is being developed in-house at the Langley Research Center. The optical position measurement system will provide six degrees of freedom position information for the LGMSS control system.

  11. Magnetic diagnostics for equilibrium reconstructions with eddy currents on the Lithium Tokamak eXperiment.

    PubMed

    Schmitt, J C; Bialek, J; Lazerson, S; Majeski, R

    2014-11-01

    The Lithium Tokamak eXperiment is a spherical tokamak with a close-fitting low-recycling wall composed of thin lithium layers evaporated onto a stainless steel-lined copper shell. Long-lived non-axisymmetric eddy currents are induced in the shell and vacuum vessel by transient plasma and coil currents and these eddy currents influence both the plasma and the magnetic diagnostic signals that are used as constraints for equilibrium reconstruction. A newly installed set of re-entrant magnetic diagnostics and internal saddle flux loops, compatible with high-temperatures and lithium environments, is discussed. Details of the axisymmetric (2D) and non-axisymmetric (3D) treatments of the eddy currents and the equilibrium reconstruction are presented. PMID:25430382

  12. Protein carbon-13 spin systems by a single two-dimensional nuclear magnetic resonance experiment

    SciTech Connect

    Oh, B.H.; Westler, W.M.; Darba, P.; Markley, J.L.

    1988-05-13

    By applying a two-dimensional double-quantum carbon-13 nuclear magnetic resonance experiment to a protein uniformly enriched to 26% carbon-13, networks of directly bonded carbon atoms were identified by virtue of their one-bond spin-spin couplings and were classified by amino acid type according to their particular single- and double-quantum chemical shift patterns. Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra. Missing spin systems corresponded primarily to residues located adjacent to the paramagnetic iron-sulfur cluster. 25 references, 2 figures.

  13. Magnetic diagnostics for equilibrium reconstructions with eddy currents on the Lithium Tokamak eXperiment.

    PubMed

    Schmitt, J C; Bialek, J; Lazerson, S; Majeski, R

    2014-11-01

    The Lithium Tokamak eXperiment is a spherical tokamak with a close-fitting low-recycling wall composed of thin lithium layers evaporated onto a stainless steel-lined copper shell. Long-lived non-axisymmetric eddy currents are induced in the shell and vacuum vessel by transient plasma and coil currents and these eddy currents influence both the plasma and the magnetic diagnostic signals that are used as constraints for equilibrium reconstruction. A newly installed set of re-entrant magnetic diagnostics and internal saddle flux loops, compatible with high-temperatures and lithium environments, is discussed. Details of the axisymmetric (2D) and non-axisymmetric (3D) treatments of the eddy currents and the equilibrium reconstruction are presented.

  14. Magnetic diagnostics for equilibrium reconstructions with eddy currents on the lithium tokamak experiment

    SciTech Connect

    Schmitt, J. C. Lazerson, S.; Majeski, R.; Bialek, J.

    2014-11-15

    The Lithium Tokamak eXperiment is a spherical tokamak with a close-fitting low-recycling wall composed of thin lithium layers evaporated onto a stainless steel-lined copper shell. Long-lived non-axisymmetric eddy currents are induced in the shell and vacuum vessel by transient plasma and coil currents and these eddy currents influence both the plasma and the magnetic diagnostic signals that are used as constraints for equilibrium reconstruction. A newly installed set of re-entrant magnetic diagnostics and internal saddle flux loops, compatible with high-temperatures and lithium environments, is discussed. Details of the axisymmetric (2D) and non-axisymmetric (3D) treatments of the eddy currents and the equilibrium reconstruction are presented.

  15. The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32.

    PubMed

    Kummer, K; Fondacaro, A; Jimenez, E; Velez-Fort, E; Amorese, A; Aspbury, M; Yakhou-Harris, F; van der Linden, P; Brookes, N B

    2016-03-01

    A new high-field magnet endstation for X-ray magnetic dichroism experiments has been installed and commissioned at the ESRF soft X-ray beamline ID32. The magnet consists of two split-pairs of superconducting coils which can generate up to 9 T along the beam and up to 4 T orthogonal to the beam. It is connected to a cluster of ultra-high-vacuum chambers that offer a comprehensive set of surface preparation and characterization techniques. The endstation and the beam properties have been designed to provide optimum experimental conditions for X-ray magnetic linear and circular dichroism experiments in the soft X-ray range between 400 and 1600 eV photon energy. User operation started in November 2014. PMID:26917134

  16. Imaging magnetic sources in the presence of superconducting surfaces : model&experiment

    SciTech Connect

    Matlachov, A. N.; Espy, M. A.; Volegov, P.; Flynn, E. R.; Maharajh, K.; Kraus, Robert H., Jr.

    2001-01-01

    The forward physics model describing the effect of a superconducting surface on the magnetic field distribution resulting from specific magnetic sources has numerous applications ranging from basic physics experiments to large superconducting magnets used in energy storage and magnetic resonance imaging. In this paper, we describe the novel application of a superconducting imaging surface (SIS) to enhance the performance of systems designed to directly observe and localize human brain function. Magnetoencephalography (MEG) measures the weak magnetic fields emanating from the brain as a direct consequence of the neuronal currents resulting from brain function[1]. The extraordinarily weak magnetic fields are measured by an array of SQUID (Superconducting QUantum Interference Device) sensors. The position and vector characteristics of these neuronal sources can be estimated from the inverse solution of the field distribution at the surface of the head. In addition, MEG temporal resolution is unsurpassed by any other method currently used for brain imaging. Although MEG source reconstruction is limited by solutions of the electromagnetic inverse problem, constraints used for source localization produce reliable results. A novel MEG system incorporating a SIS has been designed and built at Los Alamos with the goal of dramatically improving source localization accuracy while mitigating limitations of current systems (e.g. low signal-to-noise, cost, bulk). We incorporate shielding and source field measurement into an integrated design and combine the latest SQUID and data acquisition technology. The Los Alamos MEG system is based on the principal that fields from nearby sources measured by a SQUID sensor array while the SIS simultaneously shields the sensor array from distant noise fields. In general, Meissner currents flow in the surface of superconductors, preventing any significant penetration of magnetic fields. A hemispherical SIS with a brim, or helmet, surrounds

  17. Electromagnetic Emissions During Rock-fracturing Experiments Inside Magnetic Field Free Space

    NASA Astrophysics Data System (ADS)

    Wang, H.; Zhou, J.; Zhu, T.; Jin, H.

    2012-12-01

    Abnormal electromagnetic emission (EME) signal is one type of the most important precursors before earthquake, which has been widely observed and recorded before large earthquake, but the physical mechanism underlying the phenomenon is unclear and under controversy. Monitoring the EME signals during rock-fracturing experiments in laboratory is an effective way to study the phenomena and their underlying mechanism. Electromagnetic noise is everywhere because industrial and civilian electrical equipments have been widely used, which make difficulties to the in-lab experiments and field monitoring. To avoid the interference from electromagnetic noise, electromagnetic experiments must be carried out inside shielded space. Magnetic Field Free Space (MFFS) was constructed by Institute of Geophysics, China Earthquake Administration in 1980s. MFFS is a near-spherical polyhedron 'space' with 26 faces and inside diameter about 2.3 m. It is enclosed by 8-layer permalloy 1J85 for shielding magnetic field and 2-layer purified aluminium for shielding electric field. MFFS mainly shields static magnetic field by a factor of 160-4000 for the magnetic signals with the frequencies ranging from 0.01 Hz to 10 Hz. The intensity of magnetic field inside the space is less than 20 nT and its fluctuation is less than 0.3 nT in 90 hours. MFFS can dramatically shield EME signals in the frequency range of EME antennas utilized in our experiments, (several to ~320) kHz, by at least 90%, based on observation. Rock specimens (granite, marble) were fractured by two ways inside MFFS. 1) Cuboid bulk specimens were drilled, filled with static cracking agent, and then dilated from inside until fracture. 2) Cylindrical rock specimens were stressed until fracture by using a non-magnetic rock testing machine with the maximum testing force 300kN. EME, acoustic emission (AE) and strain signals were collected synchronously by the same data acquisitor, Acoustic Emission Workstation made by Physical Acoustics

  18. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    SciTech Connect

    Meier, Thomas; Haase, Jürgen

    2015-12-15

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al{sub 2}O{sub 3}), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  19. Experiments and Simulations on Magnetically Driven Implosions in High Repetition Rate Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Caballero Bendixsen, Luis; Bott-Suzuki, Simon; Cordaro, Samuel; Krishnan, Mahadevan; Chapman, Stephen; Coleman, Phil; Chittenden, Jeremy

    2015-11-01

    Results will be shown on coordinated experiments and MHD simulations on magnetically driven implosions, with an emphasis on current diffusion and heat transport. Experiments are run at a Mather-type dense plasma focus (DPF-3, Vc: 20 kV, Ip: 480 kA, E: 5.8 kJ). Typical experiments are run at 300 kA and 0.33 Hz repetition rate with different gas loads (Ar, Ne, and He) at pressures of ~ 1-3 Torr, usually gathering 1000 shots per day. Simulations are run at a 96-core HP blade server cluster using 3GHz processors with 4GB RAM per node.Preliminary results show axial and radial phase plasma sheath velocity of ~ 1x105 m/s. These are in agreement with the snow-plough model of DPFs. Peak magnetic field of ~ 1 Tesla in the radial compression phase are measured. Electron densities on the order of 1018 cm-3 anticipated. Comparison between 2D and 3D models with empirical results show a good agreement in the axial and radial phase.

  20. Models of the uniformity of electro-magnetic fields generated for biological experiments by Merritt coils.

    PubMed

    Vesper, D N; Swez, J A; Nindl, G; Fox, M T; Sandrey, M A; Balcavage, W X

    2000-01-01

    Electromagnetic field (EMF) producing wire coils were described by Merritt et al, Rev. Sci. Instrum. 54 (7), 1983. Merritt coils produce large volume EMFs in which statistical numbers of biological experiments are performed. We build and use Merritt coils for cell/animal studies and are developing therapeutic EMF systems. Here we present models illustrating the EMFs produced by our coils and discuss the criteria that should be applied to the use of Merritt and other coils to achieve valid experimental results. In a companion paper at this meeting Nindl et al, describe biological experiments, using these Merritt coils, showing that EMFs may be useful in treating many inflammatory disease states. Although the large-volume EMFs produced by Merritt coils are convenient for biological experiments the EMFs are not perfectly uniform and the deviations can be a significant source of experimental error. The orientation and size of experimental objects are key contributors to these deviations. To evaluate our Merritt coils we solved the Biot-Savart law explicitly for ideal 3-coil and 4-coil Merritt systems and compared these theoretical EMFs with those of our systems. We present a detailed examination of deviations in magnetic field amplitude, as well as magnetic field direction, as a function of location within the coils. We find that spherically shaped experimental sets minimize these deviations. We developed simple formulae for accurately predicting deviations associated with Merritt coils. PMID:10834267

  1. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa.

    PubMed

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures. PMID:26724046

  2. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    NASA Astrophysics Data System (ADS)

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  3. Simulating the magnetized liner inertial fusion plasma confinement with smaller-scale experiments [Simulating the MagLIF plasma confinement with smaller-scale experiments

    SciTech Connect

    Ryutov, D. D.; Cuneo, M. E.; Herrmann, M. C.; Sinars, D. B.; Slutz, S. A.

    2012-06-20

    The recently proposed magnetized liner inertial fusion approach to a Z-pinch driven fusion [Slutz et al., Phys. Plasmas17, 056303 (2010)] is based on the use of an axial magnetic field to provide plasma thermal insulation from the walls of the imploding liner. The characteristic plasma transport regimes in the proposed approach cover parameter domains that have not been studied yet in either magnetic confinement or inertial confinement experiments. In this article, an analysis is presented of the scalability of the key physical processes that determine the plasma confinement. The dimensionless scaling parameters are identified and conclusion is drawn that the plasma behavior in scaled-down experiments can correctly represent the full-scale plasma, provided these parameters are approximately the same in two systems. Furthermore, this observation is important in that smaller-scale experiments typically have better diagnostic access and more experiments per year are possible.

  4. DEVELOPMENT OF SUPERCONDUCTING COMBINED FUNCTION MAGNETS FOR THE PROTON TRANSPORT LINE FOR THE J-PARC NEUTRINO EXPERIMENT.

    SciTech Connect

    NAKAMOTO, T.; AJIMA, Y.; FUJII, Y.; HIGASHI, N.; ICHIKAWA, A.; KIMURA, N.; KOBAYASHI, T.; MAKIDA, Y.; OGITSU, T.; OHHATA, H.; OKAMURA, T.; SASAKI, K.; ET AL.

    2005-05-16

    Superconducting combined function magnets will be utilized for the 50 GeV, 750 kW proton beam line for the J-PARC neutrino experiment. The magnet is designed to provide a dipole field of 2.6 T combined with a quadrupole field of 19 T/m in a coil aperture of 173.4 mm at a nominal current of 7345 A. Two full-scale prototype magnets to verify the magnet performance were successfully developed. The first prototype experienced no training quench during the excitation test and good field quality was confirmed.

  5. Time-dependent dynamic behavior of light diffraction in ferrofluid

    NASA Astrophysics Data System (ADS)

    Chung, Min-Feng; Chou, S. E.; Fu, Chao-Ming

    2012-04-01

    The time-dependent dynamic behavior of diffraction patterns induced by external magnetic field in a suspension of nano-sized magnetic particles (Fe3O4) in a water-based magnetic fluid was investigated. It was observed that the diffraction pattern changed with time as the magnetic field was applied. In the absence of applied magnetic field, there was no diffraction pattern in the screen. When the magnetic field was applied, the transmitted light was perpendicular to the magnetic field, and the diffraction pattern was unstable. There were many small lines and points moving with time. After one minute, the diffraction pattern turned stable, and the small lines became longer. This time-dependent behavior helps us to understand the evolution of the forming chains of magnetic nanoparticles. Moreover, we have measured the other diffraction pattern, the transmitted light propagating parallel to the applied field. These time-dependent diffraction patterns give a new point to understand the dynamic three-dimensional structure of magnetic fluid under a dc magnetic field.

  6. Neutron diffraction study of the La1-xPrxMn2Si2 ( x=0.4, 0.7 and 1) compounds and the general description of the magnetic behavior of Mn in RMn2Ge2 and RMn2Si2

    NASA Astrophysics Data System (ADS)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; André, G.

    2007-06-01

    The magnetic structures of the La1-xPrxMn2Si2 ( x=0.4, 0.7 and 1) have been investigated by powder neutron diffraction between 2 and 308 K. According to magnetic measurements, the x=0.4 sample shows a typical SmMn2Ge2-like magnetic behavior. Neutron diffraction indicates a canted antiferromagnetic structure below 130 K and a canted ferromagnetic structure above 240 K. Between 130 and 240 K, the canted ferromagnetic and antiferromagnetic structures coexist. Since the magnetic moments of Mn atoms, the unit cell parameters and the scale parameters of the canted antiferromagnetism and canted ferromagnetism are highly correlated between 130 and 240 K, a special refinement procedure was introduced. The critical Mn-Mn value was determined as 2.87 A˚, and the spontaneous volume change and linear magnetostriction are derived. Neutron diffraction revealed a canted antiferromagnetic structure for La0.3Pr0.7Mn2Si2. A canted antiferromagnetic structure was also detected for PrMn2Si2 by neutron diffraction in contrast to previous reports of a collinear arrangement. The present results are compiled together with previous ones on RMn2Ge2 and RMn2Si2 (R: Y, La and rare-earth) compounds in two magnetic phase diagrams. These two graphics summarize the general magnetic behavior of Mn in the RMn2Ge2 and RMn2Si2 compounds.

  7. Dirac: A campaign of experiments to study physics and chemistry at ultrahigh magnetic fields

    SciTech Connect

    Solem, J.C.; Fowler, C.M.; Goettee, J.D.; Rickel, D.; Campbell, L.J.; Veeser, L.

    1996-12-01

    We present an overview of the Dirac experimental campaign conducted at Los Alamos in spring of 1996. The name was chosen in recognition of P.A.M. Dirac`s monumental contributions to quantum theory, which affected every aspect of the science we planned to investigate. We show how the various collaborations were put together, discuss some of the difficulties of collecting data in rapidly changing magnetic fields, describe the motivation, packaging, and integration of experiments, and give an exceedingly preliminary discussion of some of the results.

  8. The Alpha Magnetic Spectrometer (AMS) experiment on the International Space Station

    NASA Astrophysics Data System (ADS)

    Alpat, Behcet

    2001-04-01

    The Alpha Magnetic Spectrometer (AMS) is a detector designed to operate in space to search for antimatter components in cosmic ray, the annihilation products of darkmatter and to study the antiprotons, positrons and light nuclei. A 'baseline' version of the experiment has successfully completed the precursor flight on Space Shuttle Discovery (June 2-12, 1998). The complete AMS is programmed for installation on International Space Station in year 2003 for an operational period of 3 years. In this contribution we report on the experimental configuration of AMS that will be installed on International Space Station.

  9. High coherent bi-chromatic laser with gigahertz splitting produced by the high diffraction orders of acousto-optic modulator used for coherent population trapping experiments.

    PubMed

    Yun, Peter; Tan, Bozhong; Deng, Wei; Gu, Sihong

    2011-12-01

    To prepare the coherent population trapping (CPT) states with rubidium and cesium, the commonly used atoms in CPT studies, a coherent bi-chromatic light field with frequency difference of several GHz is a basic requirement. With a 200 MHz center frequency acousto-optic modulator (AOM), we have realized bi-chromatic laser fields with several GHz frequency splits through high diffraction orders. We have experimentally studied the coherence between two frequency components of a bi-chromatic laser beam, which is composed of ±6 orders with frequency split of 3 GHz diffracted from the same laser beam, and the measured residual phase noise is Δφ(2)<0.019 rad(2). The bi-chromatic laser fields were used to prepare CPT states with (85)Rb and (87)Rb atoms, and high contrast CPT signals were obtained. For CPT states preparation, our study result shows that it is a feasible approach to generate the bi-chromatic light field with larger frequency splits through high diffraction orders of AOM.

  10. Fresnel Diffraction for CTR Microbunching

    SciTech Connect

    Tikhoplav, R.; Knyazik, A.; Rosenzweig, J. B.; Andonian, G.

    2009-01-22

    Laser beams of high intensities are routinely used for IFEL experiments. Such beams can potentially destroy microbunching diagnostic tools such as coherent transition radiation foils due to their low damage thresholds. Near-field Fresnel diffraction scheme for termination of CO{sub 2} laser beam has been experimentally studied and is presented in this paper. Novel THz camera was utilized for such study.

  11. Hard diffraction and rapidity gaps

    SciTech Connect

    Albrow, M.G.

    1994-08-01

    I describe the evolution of experiments at hadron colliders on (a) high mass diffraction (b) double pomeron exchange, from the ISR through the Sp{bar p}S to the Tevatron. I emphasize an experimental approach to the question: ``What is the pomeron?``

  12. Magnetic Field Observations from the Dynamic Ionosphere CubeSat Experiment (DICE)

    NASA Astrophysics Data System (ADS)

    Pilinski, M.; Wilder, F. D.; Crowley, G.; Azeem, S. I.; Swenson, C.; Fish, C. S.; Neilsen, T. L.; Barjatya, A.

    2012-12-01

    The Dynamic Ionosphere CubeSat Experiment (DICE) was launched on October 28, 2011 with the primary mission objective to study and characterize ionospheric Storm Enhanced Density (SED) bulges and plumes. The mission consists of two spacecraft, each containing two Langmuir probes to measure ionospheric in-situ plasma densities, as well as electric field probes and a magnetometer to measure AC and DC electromagnetic fields. The mission is still in the commissioning and engineering check-out phase, but all instruments appear to be healthy. The Langmuir Probes are fully deployed, and data has been collected from them as well as from the science magnetometer. The final commissioning task is the deployment of the electric field booms. This work presents data from the on-board magnetometers. Background geomagnetic field values are subtracted to investigate magnetic perturbations at high latitudes due to Field Aligned Currents (FACs). These perturbations are compared to AMPERE fitted magnetic residuals. DICE Langmuir probe measurements are also compared with the magnetic residuals to investigate the effect of FACs and particle precipitation on the overall electron density in the ionosphere.

  13. Experiences with the magnetism of conducting loops: Historical instruments, experimental replications, and productive confusions

    NASA Astrophysics Data System (ADS)

    Cavicchi, Elizabeth

    2003-02-01

    This study investigates nineteenth century laboratory work on electromagnetism through historical accounts and experimental replications. Oersted found that when a magnetic needle was placed in varying positions around a conducting wire, its orientation changed: in moving from a spot above the wire to one below, its sense inverted. This behavior was confusing and provocative. Early experimenters such as Johann Schweigger, Johann Poggendorff, and James Cumming engaged it by bending wire into loops. These loops, which increased the magnetic effect on a compass placed within, also provided evidence of their understanding and confusion. Coiling conducting wires around iron magnetized it, but when some wires coiled oppositely from others, the effect diminished. This effect confused contemporaries of Joseph Henry who made electromagnets, and amateurs later in the century who constructed multisection induction coils. I experienced these confusions myself while working with multilayer coils and induction coils that I made to replicate the historical instruments. This study shows how confusion can be a productive element in learning, by engaging learners to ask questions and invent experiments. By providing space for learners' confusions, teachers can support the development of their students' physical understandings.

  14. Hydromagnetic Dynamics and Magnetic Field Enhancement in a Turbulent Spherical Couette Experiment

    NASA Astrophysics Data System (ADS)

    Stone, D. S.; Liu, Q.; Zimmerman, D. S.; Triana, S. A.; Nataf, H. C.; Lathrop, D. P.

    2014-11-01

    The University of Maryland Three Meter Geodynamo, a spherical Couette experiment filled with liquid sodium and geometrically similar to the earth's core, is used to study hydrodynamic and hydromagnetic phenomena in rapidly rotating turbulence. Turbulent flow is driven in the sodium by differential rotation of the inner and outer spherical shells, while an external coil applies a magnetic field in order to study hydromagnetic effects relevant to the earth's outer core such as dynamo action. An array of 31 external Hall sensors measures the Gauss coefficients of the resulting magnetic field. The flow state is strongly dependent on Rossby number Ro = (ΩI -ΩO) /ΩO , where ΩI and ΩO are the inner and outer sphere rotation frequencies. The flow state is inferred from the torque required to drive the inner sphere and the generation of internal toroidal magnetic field through the Ω-effect, which is measured by a Hall probe inserted into the sodium. A self-sustaining dynamo has not yet been observed at rotation speeds up to about half of the design maximum. However, continuous dipole amplification up to 12% of a small applied field has been observed at Ro = - 17 . 7 while bursts of dipole field have been observed up to 15% of a large external applied field at Ro = + 6 . 0 and up to 20% of a small applied field at Ro = + 2 . 15 .

  15. Understanding magnetic nanoparticle osteoblast receptor-mediated endocytosis using experiments and modeling

    NASA Astrophysics Data System (ADS)

    Tran, Nhiem; Webster, Thomas J.

    2013-05-01

    Iron oxide nanoparticles are promising candidates for controlling drug delivery through an external magnetic force to treat a wide range of diseases, including osteoporosis. Previous studies have demonstrated that in the presence of hydroxyapatite coated magnetite (Fe3O4) nanoparticles, osteoblast (or bone forming cell) proliferation and long-term functions (such as calcium deposition) were significantly enhanced. Hydroxyapatite is the major inorganic component of bone. As a further attempt to understand why, in the current study, the uptake of such nanoparticles into osteoblasts was experimentally investigated and mathematically modeled. Magnetite nanoparticles were synthesized using a co-precipitation method and were coated with hydroxyapatite. A cellular uptake experiment at low temperatures indicated that receptor-mediated endocytosis contributed to the internalization of the magnetic nanoparticles into osteoblasts. A model was further developed to explain the uptake of magnetic nanoparticles into osteoblasts using receptor-mediated endocytosis. This model may explain the internalization of hydroxyapatite into osteoblasts to elevate intracellular calcium levels necessary to promote osteoblast functions to treat a wide range of orthopedic problems, including osteoporosis.

  16. THE ROTATING MAGNETIC FIELD OSCILLATOR SYSTEM FOR CURRENT DRIVE IN THE TRANSLATION, CONFINEMENT AND SUSTAINMENT EXPERIMENT

    SciTech Connect

    S. TOBIN; ET AL

    2000-12-01

    The experimental setup and test results for the {approximately}125 MW rotating magnetic field current drive system of the Translation, Confinement and Sustainment Experiment at the University of Washington are described. The oscillator system, constructed at Los Alamos National Laboratory, drives two tank circuits (15 kV{sub peak} potential, 8.5 kA{sub peak} maximum circulating current in each tank to date) operated 90{degree} out of phase to produce a 54 G rotating magnetic field with a frequency of 163 kHz ({omega} = 1.02{sup x} 10{sup {minus}6} s{sup {minus}1}). Programmable waveform generators control ''hot deck'' totem pole drivers that are used to control the grid of 12 Machlett 8618 magnetically beamed triode tubes. This setup allows the current to be turned on or off in less than 100 ns ({approximately}6{degree}). Both tank circuits are isolated from the current source by a 1:1 air core, transmission line transformer. Each tank circuit contains two saddle coils (combined inductance of 1.6 {micro}H) and radio frequency capacitors (580 nF). Test results are presented for three conditions: no external load, a resistive external load and a plasma load. A SPICE model of the oscillator system was created. Comparisons between this model and experimental data are given.

  17. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  18. Comparison between initial Magnetized Liner Inertial Fusion experiments and integrated simulations

    NASA Astrophysics Data System (ADS)

    Sefkow, A. B.; Gomez, M. R.; Geissel, M.; Hahn, K. D.; Hansen, S. B.; Harding, E. C.; Peterson, K. J.; Slutz, S. A.; Koning, J. M.; Marinak, M. M.

    2014-10-01

    The Magnetized Liner Inertial Fusion (MagLIF) approach to ICF has obtained thermonuclear fusion yields using the Z facility. Integrated magnetohydrodynamic simulations provided the design for the first neutron-producing experiments using capabilities that presently exist, and the initial experiments measured stagnation radii rstag < 75 μm, temperatures around 3 keV, and isotropic neutron yields up to YnDD = 2 ×1012 from imploded liners reaching peak velocities around 70 km/s over an implosion time of about 60 ns. We present comparisons between the experimental observables and post-shot degraded integrated simulations. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  19. Evaluation of Possible Nuclear Magnetic Resonance Diagnostic Techniques for Tokamak Experiments

    SciTech Connect

    S.J. Zweben; T.W. Kornack; D. Majeski; G. Schilling; C.H. Skinner; R. Wilson

    2002-08-05

    Potential applications of nuclear magnetic resonance (NMR) diagnostic techniques to tokamak experiments are evaluated. NMR frequencies for hydrogen isotopes and low-Z nuclei in such experiments are in the frequency range approximately equal to 20-200 MHz, so existing RF [radio-frequency] antennas could be used to rotate the spin polarization and to make the NMR measurements. Our tentative conclusion is that such measurements are possible if highly spin polarized H or (superscript)3He gas sources (which exist) are used to fuel these plasmas. In addition, NMR measurements of the surface layers of the first wall (without plasma) may also be possible, e.g., to evaluate the inventory of tritium inside the vessel.

  20. The Rome-GSFC magnetic field experiment for Helios A and B /E 3/. [geomagnetic measurements

    NASA Technical Reports Server (NTRS)

    Scearce, C.; Ness, N.; Burlaga, L.; Cantarano, S.; Terenzi, R.; Mariani, F.

    1975-01-01

    The Rome-GSFC magnetic field experiment utilizes a triaxial fluxgate (saturable inductor) magnetometer. The sensor unit is mounted on the end of a boom approximately four meters from the spacecraft spin axis. The three analog outputs of the magnetometer are converted into three 9 bit digital words. The experiment utilizes an automatic inflight range switch to select the optimum dynamic range out of 4 ranges. A nonmagnetic thermally oscillating actuator is used to reorient the sensor unit by 90 deg to determine all three axes zero levels. The accuracy should be approximately plus or minus 0.1 gamma. The vector measurements are made at equal intervals in time ranging from 16 per second down to 1 per second depending on the telemetry bit rate.

  1. Structure of nanocrystalline calcium silicate hydrates: insights from X-ray diffraction, synchrotron X-ray absorption and nuclear magnetic resonance

    PubMed Central

    Grangeon, Sylvain; Claret, Francis; Roosz, Cédric; Sato, Tsutomu; Gaboreau, Stéphane; Linard, Yannick

    2016-01-01

    The structure of nanocrystalline calcium silicate hydrates (C–S–H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied using an electron probe micro-analyser, powder X-ray diffraction, 29Si magic angle spinning NMR, and Fourier-transform infrared and synchrotron X-ray absorption spectroscopies. All samples can be described as nanocrystalline and defective tobermorite. At low Ca/Si ratio, the Si chains are defect free and the Si Q 3 and Q 2 environments account, respectively, for up to 40.2 ± 1.5% and 55.6 ± 3.0% of the total Si, with part of the Q 3 Si being attributable to remnants of the synthesis reactant. As the Ca/Si ratio increases up to 0.87 ± 0.02, the Si Q 3 environment decreases down to 0 and is preferentially replaced by the Q 2 environment, which reaches 87.9 ± 2.0%. At higher ratios, Q 2 decreases down to 32.0 ± 7.6% for Ca/Si = 1.38 ± 0.03 and is replaced by the Q 1 environment, which peaks at 68.1 ± 3.8%. The combination of X-ray diffraction and NMR allowed capturing the depolymerization of Si chains as well as a two-step variation in the layer-to-layer distance. This latter first increases from ∼11.3 Å (for samples having a Ca/Si ratio <∼0.6) up to 12.25 Å at Ca/Si = 0.87 ± 0.02, probably as a result of a weaker layer-to-layer connectivity, and then decreases down to 11 Å when the Ca/Si ratio reaches 1.38 ± 0.03. The decrease in layer-to-layer distance results from the incorporation of interlayer Ca that may form a Ca(OH)2-like structure, nanocrystalline and intermixed with C–S–H layers, at high Ca/Si ratios. PMID:27275135

  2. Complex magnetic field exposure system for in vitro experiments at intermediate frequencies.

    PubMed

    Lodato, Rossella; Merla, Caterina; Pinto, Rosanna; Mancini, Sergio; Lopresto, Vanni; Lovisolo, Giorgio A

    2013-04-01

    In occupational environments, an increasing number of electromagnetic sources emitting complex magnetic field waveforms in the range of intermediate frequencies is present, requiring an accurate exposure risk assessment with both in vitro and in vivo experiments. In this article, an in vitro exposure system able to generate complex magnetic flux density B-fields, reproducing signals from actual intermediate frequency sources such as magnetic resonance imaging (MRI) scanners, for instance, is developed and validated. The system consists of a magnetic field generation system and an exposure apparatus realized with a couple of square coils. A wide homogeneity (99.9%) volume of 210 × 210 × 110 mm(3) was obtained within the coils, with the possibility of simultaneous exposure of a large number of standard Petri dishes. The system is able to process any numerical input sequence through a filtering technique aimed at compensating the coils' impedance effect. The B-field, measured in proximity to a 1.5 T MRI bore during a typical examination, was excellently reproduced (cross-correlation index of 0.99). Thus, it confirms the ability of the proposed setup to accurately simulate complex waveforms in the intermediate frequency band. Suitable field levels were also attained. Moreover, a dosimetry index based on the weighted-peak method was evaluated considering the induced E-field on a Petri dish exposed to the reproduced complex B-field. The weighted-peak index was equal to 0.028 for the induced E-field, indicating an exposure level compliant with the basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Bioelectromagnetics 34:211-219, 2013. © 2012 Wiley Periodicals, Inc. PMID:23060274

  3. Complex magnetic field exposure system for in vitro experiments at intermediate frequencies.

    PubMed

    Lodato, Rossella; Merla, Caterina; Pinto, Rosanna; Mancini, Sergio; Lopresto, Vanni; Lovisolo, Giorgio A

    2013-04-01

    In occupational environments, an increasing number of electromagnetic sources emitting complex magnetic field waveforms in the range of intermediate frequencies is present, requiring an accurate exposure risk assessment with both in vitro and in vivo experiments. In this article, an in vitro exposure system able to generate complex magnetic flux density B-fields, reproducing signals from actual intermediate frequency sources such as magnetic resonance imaging (MRI) scanners, for instance, is developed and validated. The system consists of a magnetic field generation system and an exposure apparatus realized with a couple of square coils. A wide homogeneity (99.9%) volume of 210 × 210 × 110 mm(3) was obtained within the coils, with the possibility of simultaneous exposure of a large number of standard Petri dishes. The system is able to process any numerical input sequence through a filtering technique aimed at compensating the coils' impedance effect. The B-field, measured in proximity to a 1.5 T MRI bore during a typical examination, was excellently reproduced (cross-correlation index of 0.99). Thus, it confirms the ability of the proposed setup to accurately simulate complex waveforms in the intermediate frequency band. Suitable field levels were also attained. Moreover, a dosimetry index based on the weighted-peak method was evaluated considering the induced E-field on a Petri dish exposed to the reproduced complex B-field. The weighted-peak index was equal to 0.028 for the induced E-field, indicating an exposure level compliant with the basic restrictions of the International Commission on Non-Ionizing Radiation Protection. Bioelectromagnetics 34:211-219, 2013. © 2012 Wiley Periodicals, Inc.

  4. Beryllium liner implosion experiments on the Z accelerator in preparation for magnetized liner inertial fusion

    SciTech Connect

    McBride, R. D.; Martin, M. R.; Lemke, R. W.; Jennings, C. A.; Rovang, D. C.; Sinars, D. B.; Cuneo, M. E.; Herrmann, M. C.; Slutz, S. A.; Nakhleh, C. W.; Davis, J.-P.; Flicker, D. G.; Rogers, T. J.; Robertson, G. K.; Kamm, R. J.; Smith, I. C.; Savage, M.; Stygar, W. A.; Rochau, G. A.; Jones, M.; and others

    2013-05-15

    Multiple experimental campaigns have been executed to study the implosions of initially solid beryllium (Be) liners (tubes) on the Z pulsed-power accelerator. The implosions were driven by current pulses that rose from 0 to 20 MA in either 100 or 200 ns (200 ns for pulse shaping experiments). These studies were conducted in support of the recently proposed Magnetized Liner Inertial Fusion concept [Slutz et al., Phys. Plasmas 17, 056303 (2010)], as well as for exploring novel equation-of-state measurement techniques. The experiments used thick-walled liners that had an aspect ratio (initial outer radius divided by initial wall thickness) of either 3.2, 4, or 6. From these studies, we present three new primary results. First, we present radiographic images of imploding Be liners, where each liner contained a thin aluminum sleeve for enhancing the contrast and visibility of the liner's inner surface in the images. These images allow us to assess the stability of the liner's inner surface more accurately and more directly than was previously possible. Second, we present radiographic images taken early in the implosion (prior to any motion of the liner's inner surface) of a shockwave propagating radially inward through the liner wall. Radial mass density profiles from these shock compression experiments are contrasted with profiles from experiments where the Z accelerator's pulse shaping capabilities were used to achieve shockless (“quasi-isentropic”) liner compression. Third, we present “micro-B-dot ” measurements of azimuthal magnetic field penetration into the initially vacuum-filled interior of a shocked liner. Our measurements and simulations reveal that the penetration commences shortly after the shockwave breaks out from the liner's inner surface. The field then accelerates this low-density “precursor” plasma to the axis of symmetry.

  5. Aircraft noise propagation. [sound diffraction by wings

    NASA Technical Reports Server (NTRS)

    Hadden, W. J.; Pierce, A. D.

    1978-01-01

    Sound diffraction experiments conducted at NASA Langley Research Center to study the acoustical implications of the engine over wing configuration (noise-shielding by wing) and to provide a data base for assessing various theoretical approaches to the problem of aircraft noise reduction are described. Topics explored include the theory of sound diffraction around screens and wedges; the scattering of spherical waves by rectangular patches; plane wave diffraction by a wedge with finite impedence; and the effects of ambient flow and distribution sources.

  6. Numerical modeling of laser-driven experiments of colliding jets: Turbulent amplification of seed magnetic fields

    NASA Astrophysics Data System (ADS)

    Tzeferacos, Petros; Fatenejad, Milad; Flocke, Norbert; Graziani, Carlo; Gregori, Gianluca; Lamb, Donald; Lee, Dongwook; Meinecke, Jena; Scopatz, Anthony; Weide, Klaus

    2014-10-01

    In this study we present high-resolution numerical simulations of laboratory experiments that study the turbulent amplification of magnetic fields generated by laser-driven colliding jets. The radiative magneto-hydrodynamic (MHD) simulations discussed here were performed with the FLASH code and have assisted in the analysis of the experimental results obtained from the Vulcan laser facility. In these experiments, a pair of thin Carbon foils is placed in an Argon-filled chamber and is illuminated to create counter-propagating jets. The jets carry magnetic fields generated by the Biermann battery mechanism and collide to form a highly turbulent region. The interaction is probed using a wealth of diagnostics, including induction coils that are capable of providing the field strength and directionality at a specific point in space. The latter have revealed a significant increase in the field's strength due to turbulent amplification. Our FLASH simulations have allowed us to reproduce the experimental findings and to disentangle the complex processes and dynamics involved in the colliding flows. This work was supported in part at the University of Chicago by DOE NNSA ASC.

  7. Study of Multiple Scale Physics of Magnetic Reconnection on the FLARE (Facility for Laboratory Reconnection Experiments)

    NASA Astrophysics Data System (ADS)

    Ji, H.; Bhattacharjee, A.; Prager, S.; Daughton, W. S.; Bale, S. D.; Carter, T. A.; Crocker, N.; Drake, J. F.; Egedal, J.; Sarff, J.; Wallace, J.; Chen, Y.; Cutler, R.; Fox, W. R., II; Heitzenroeder, P.; Kalish, M.; Jara-Almonte, J.; Myers, C. E.; Ren, Y.; Yamada, M.; Yoo, J.

    2015-12-01

    The FLARE device (flare.pppl.gov) is a new intermediate-scale plasma experiment under construction at Princeton to study magnetic reconnection in regimes directly relevant to space, solar and astrophysical plasmas. The existing small-scale experiments have been focusing on the single X-line reconnection process either with small effective sizes or at low Lundquist numbers, but both of which are typically very large in natural plasmas. The configuration of the FLARE device is designed to provide experimental access to the new regimes involving multiple X-lines, as guided by a reconnection "phase diagram" [Ji & Daughton, PoP (2011)]. Most of major components of the FLARE device have been designed and are under construction. The device will be assembled and installed in 2016, followed by commissioning and operation in 2017. The planned research on FLARE as a user facility will be discussed on topics including the multiple scale nature of magnetic reconnection from global fluid scales to ion and electron kinetic scales. Results from scoping simulations based on particle and fluid codes and possible comparative research with space measurements will be presented.

  8. Effects of self generated magnetic fields and non local heat transport in laser experiments.

    NASA Astrophysics Data System (ADS)

    Schurtz, Guy; Nicolai, Philippe; Dattolo, Evelyne; Babonneau, Danielle

    2002-11-01

    Electron conduction is known to be a leading transport process in laser created plasmas. Several effects may cause the heat flux to depart from the classical linear Spitzer-Harm theory. First of all, kinetic effects result in the non locality of the heat flux in case of strong temperature gradients. A two dimensionnal non local model has been developed by the authors and implemented in the FCI2 hydrocode (G.P. Schurtz et al., Ph.Plasmas,7,10,4238, 2000). Conduction may also be affected by magnetic fields. FCI2 simulations including a MHD model and Braginskii conduction indicate that magnetic fields with intensities up to several MG may be generated and strongly inhibit electron heat flow. In this communication, we briefly discuss the strategy we use in FCI2 in order to couple both models and compare code predictions to experimental data over a wide range of experiments in open and close (hohlraum) geometries. As compared to flux limited Spitzer Harm conduction, this new model succeeds as well in restituting global energy balance (e.g. radiation production in hohlraums) but predicts large differences in hydrodynamics, which are actually observed in experiments.

  9. Self-generated magnetic fields in direct-drive implosion experiments

    NASA Astrophysics Data System (ADS)

    Igumenshchev, I. V.; Zylstra, A. B.; Li, C. K.; Nilson, P. M.; Goncharov, V. N.; Petrasso, R. D.

    2014-06-01

    Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ˜10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ˜1015 W/cm2. Proton radiographs show multiple ring-like structures produced by electric fields ˜107 V/cm and fine structures from surface defects, indicating self-generated fields up to ˜3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇Te × ∇ne source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

  10. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    DOE PAGES

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Cooper, G. W.; Gomez, M. R.; Slutz, S.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; et al

    2016-05-01

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ~2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner ~ 1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Furthermore, plans to improve and expandmore » the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.« less

  11. Monolayer to interdigitated partial bilayer smectic C transition in thiophene-based spacer mesogens: X-ray diffraction and (13)C nuclear magnetic resonance studies.

    PubMed

    Kesava Reddy, M; Varathan, E; Lobo, Nitin P; Roy, Arun; Narasimhaswamy, T; Ramanathan, K V

    2015-10-01

    Mesophase organization of molecules built with thiophene at the center and linked via flexible spacers to rigid side arm core units and terminal alkoxy chains has been investigated. Thirty homologues realized by varying the span of the spacers as well as the length of the terminal chains have been studied. In addition to the enantiotropic nematic phase observed for all the mesogens, the increase of the spacer as well as the terminal chain lengths resulted in the smectic C phase. The molecular organization in the smectic phase as investigated by temperature dependent X-ray diffraction measurements revealed an interesting behavior that depended on the length of the spacer vis-a-vis the length of the terminal chain. Thus, a tilted interdigitated partial bilayer organization was observed for molecules with a shorter spacer length, while a tilted monolayer arrangement was observed for those with a longer spacer length. High-resolution solid state (13)C NMR studies carried out for representative mesogens indicated a U-shape for all the molecules, indicating that intermolecular interactions and molecular dynamics rather than molecular shape are responsible for the observed behavior. Models for the mesophase organization have been considered and the results understood in terms of segregation of incompatible parts of the mesogens combined with steric frustration leading to the observed lamellar order.

  12. Lensless reflective point diffraction interferometer.

    PubMed

    Zhu, Wenhua; Chen, Lei; Zheng, Donghui; Yang, Ying; Han, Zhigang; Li, Jinpeng

    2016-07-01

    A lensless reflective point diffraction interferometer (LRPDI) is proposed for dynamic wavefront measurement. The point diffraction interferometer is integrated on a small substrate with properly designed thin film, which is used for generating the interferogram with high carrier frequency at a CCD target. By lensless imaging, the complex amplitude at the CCD target can be propagated to the conjugated plane of the exit pupil of an incident wavefront, which not only avoids the edge diffraction in the interferogram, but also eliminates systematic error. The accuracy of LRPDI is demonstrated by simulation and experiment, and a precision better than 1/150 wavelength is achieved. The new design with lensless imaging processing is suitable for dynamic wavefront measurement. PMID:27409204

  13. Ultrafast x-ray diffraction of laser-irradiated crystals

    NASA Astrophysics Data System (ADS)

    Heimann, P. A.; Larsson, J.; Chang, Z.; Lindenberg, A.; Schuck, P. J.; Judd, E.; Padmore, H. A.; Bucksbaum, P. H.; Lee, R. W.; Murnane, M.; Kapteyn, H.; Wark, J. S.; Falcone, R. W.

    1997-07-01

    An apparatus has been developed for measuring time-dependent x-ray diffraction. X-ray pulses from an Advanced Light Source bend magnet are diffracted by a sagittally-focusing Si (111) crystal and then by a sample crystal, presently InSb (111). Laser pulses with 100 fs duration and a repetition rate of 1 KHz irradiate the sample inducing a phase transition. Two types of detectors are being employed: an x-ray streak camera and an avalanche photodiode. The streak camera is driven by a photoconductive switch and has a 2 ps temporal resolution determined by trigger jitter. The avalanche photodiode has high quantum efficiency and sufficient time resolution to detect single x-ray pulses in ALS two bunch or `camshaft' operation. A beamline is under construction dedicated for time resolved and micro-diffraction experiments. In the new beamline a toroidal mirror collects 3 mrad horizontally and makes a 1:1 image of the bend magnet source in the x-ray hutch. A laser induced phase transition has been observed in InSb occurring within 70 ps.

  14. Evaluation of commercial magnetic iron oxides as sediment tracers in water erosion experiments

    NASA Astrophysics Data System (ADS)

    Guzman, G.; Barron, V.; Gomez, J. A.

    2009-04-01

    Water erosion is one of the mayor concerns to sustainability of agricultural systems in Mediterranean countries, e.g. olive farming areas in Southern Spain. Despite an increase in the number of published studies on erosion rates and conservation measures, significant uncertainty persists on actual erosion rates in these areas (Gómez et al., 2008; Fleskens and Stroosnijder, 2007). Due to the limitations and cost of technologies traditionally used in erosion measurement, there is a growing interest in the use of innovative erosion tracers that could be applied to the soil and used to monitor erosion and deposition rates at experiments performed at different scales and environments. An example of these innovative traces, which could complement the potential of more traditional tracers like Cs-137, is rare earths oxides. Due to its size, D50 ranging from 1.23 to 16.38 m (Zhang et al., 2003), these rare earth oxides tagged soil aggregates more or less homogeneously and have been used in tracking sediment movement at laboratory and field scale, e.g. Polyakov and Nearing, (2004). One of the shortcomings of the use of rare earth oxides in the cost derived of the need to use Inductive Coupled Plasma Mass Spectrometry to determine its concentration in the tagged soil. The use of mineral magnetic measurements provide a less expensive alternative to complement erosion and sediment delivery in eroding landscapes (Royall, 2001), and is also an area of active research. However, most of the studies are based on measurements of magnetic properties inherent to soil materials, and little research has been done about the possibility of tagging soils with magnetic materials. Ventura et al. (2002) tagged a loamy soil with a magnetic tracer for use in rainfall simulation experiments. They concluded that the magnetic tracer used, magnetic beads of 3.2 mm of mean weight diameter, although useful in determining erosion and deposition areas presented a tracer to soil ratio that did not

  15. A Next-Generation Experiment To Study Magnetic Reconnection and Related Explosive Phenomena in Large and Collisionless Plasmas

    NASA Astrophysics Data System (ADS)

    Ji, H.; Yamada, M.; Prager, S.; Daughton, W.; Roytershteyn, V.

    2009-11-01

    Magnetic reconnection, a topological change in magnetic field in plasmas, often occurs explosively leading to rapid conversion of magnetic energy to plasma particle energy in space, astrophysical and laboratory fusion plasmas. The Magnetic Reconnection Experiment (MRX, http://mrx.pppl.gov) is a primary dedicated experiment to study reconnection in a controlled environment. However, further critical understanding and contributions to space and astrophysical plasmas are limited by the parameters achievable in MRX and other dedicated experiments. The MRX plasmas are relatively collisional (Lundquist numbers S ˜10^3) and effectively small (plasma size normalized by ion skin depth or ion sound radius ˜10). In this paper, we discuss plans for a next-generation reconnection experiment based on MRX. By a combination of larger physical size, stronger magnetic field, and higher heating power, we aim to increase S by a factor of 100 and effective size by a factor of 10, representing a very large jump in the laboratory capabilities. Kinetic simulations in realistic boundaries will be used to guide the experimental design. Research topics include: (1) transition of collisional to collisionless reconnection and its scaling with collisionality and size, (2) interacting multiple reconnections as a possible cause of explosive phenomena, (3) particle energization by reconnection, (4) relation between local reconnection and global magnetic self-organization in 3D realistic geometry and boundary.

  16. Understanding magnetic remanence acquisition through combined synthetic sediment deposition experiments and numerical simulations.

    NASA Astrophysics Data System (ADS)

    Bilardello, D.

    2014-12-01

    Understanding depositional remanent magnetizations (DRMs) bears implications on interpreting paleomagnetic and paleointensity records extracted from sedimentary rocks. Laboratory deposition experiments have yielded DRMs with shallow remanent inclinations and revealed a field dependence of the magnetization (M), which is orders of magnitude lower than the saturation remanence. To investigate these observations further, experiments involving differently shaped particles were performed. Spherical particles confirmed the field dependence of both the inclination error and M and the fact that the DRM acquired experimentally is lower than saturation. A sediment concentration dependence of the inclination error was observed, indicating a dependance of the inclination error on the sediment load/burial depth or the sedimentation rate. Other outcome was the certainty that spherical particles alone can lead to substantial inclination shallowing. Numerical simulations of settling spherical particles indicated that DRM should be ~10 times lower than the saturation remanence and predicted that rolling of the grains on the sediment surface and particle interactions during settling can produce a substantial shallowing of the inclination and lowering of the remanence, bringing the simulations in close agreement to the experimental results. Experiments involving platy particles, instead allowed interesting comparisons and gave insight into the behavior of differently shaped particles, for instance yielding smaller amounts of shallowing than spheres, in contrast to general belief. Viewing DRM as an anisotropic process allows fitting the experimental results with tensors (kDRM). The ratios of kvertical over khorizontal are in good agreement to the ratios of M obtained in vertical over horizontal experimental fields, which should be equivalent to the widely used inclination shallowing factor f. Experimental results were highly repeatabile, however not always as repeatable for both M and

  17. Investigating the effect of tumor vascularization on magnetic targeting in vivo using retrospective design of experiment.

    PubMed

    Mei, Kuo-Ching; Bai, Jie; Lorrio, Silvia; Wang, Julie Tzu-Wen; Al-Jamal, Khuloud T

    2016-11-01

    Nanocarriers take advantages of the enhanced permeability and retention (EPR) to accumulate passively in solid tumors. Magnetic targeting has shown to further enhance tumor accumulation in response to a magnetic field gradient. It is widely known that passive accumulation of nanocarriers varies hugely in tumor tissues of different tumor vascularization. It is hypothesized that magnetic targeting is likely to be influenced by such factors. In this work, magnetic targeting is assessed in a range of subcutaneously implanted murine tumors, namely, colon (CT26), breast (4T1), lung (Lewis lung carcinoma) cancer and melanoma (B16F10). Passively- and magnetically-driven tumor accumulation of the radiolabeled polymeric magnetic nanocapsules are assessed with gamma counting. The influence of tumor vasculature, namely, the tumor microvessel density, permeability and diameter on passive and magnetic tumor targeting is assessed with the aid of the retrospective design of experiment (DoE) approach. It is clear that the three tumor vascular parameters contribute greatly to both passive and magnetically targeted tumor accumulation but play different roles when nanocarriers are targeted to the tumor with different strategies. It is concluded that tumor permeability is a rate-limiting factor in both targeting modes. Diameter and microvessel density influence passive and magnetic tumor targeting, respectively. PMID:27573135

  18. Enclosed chambers for humidity control and sample containment in fiber diffraction

    SciTech Connect

    McDonald, M.; Kendall, A.; Tanaka, M.; Weissman, J.S.; Stubbs, G.

    2008-11-03

    A chamber and stretch frame for making fibers for diffraction is described. The chamber is made from a simple plastic cuvette with silicon nitride windows. It is suitable for maintaining constant humidity during fiber drying and data collection, and allows stretching of the fiber and exposure to magnetic fields during sample preparation. If necessary, it provides primary containment for toxic and infectious biological materials. The chamber has been used in fiber diffraction experiments with filamentous plant viruses and a yeast prion protein, and is shown to produce excellent orientation and to maintain hydration and order at the molecular level.

  19. Enclosed Chambers for Humidity Control And Sample Containment in Fiber Diffraction

    SciTech Connect

    McDonald, M.; Kendall, A.; Tanaka, M.; Weissman, J.S.; Stubbs, G.

    2009-05-26

    A chamber and stretch frame for making fibers for diffraction is described. The chamber is made from a simple plastic cuvette with silicon nitride windows. It is suitable for maintaining constant humidity during fiber drying and data collection, and allows stretching of the fiber and exposure to magnetic fields during sample preparation. If necessary, it provides primary containment for toxic and infectious biological materials. The chamber has been used in fiber diffraction experiments with filamentous plant viruses and a yeast prion protein, and is shown to produce excellent orientation and to maintain hydration and order at the molecular level.

  20. Commissioning of Angle Dispersive X-ray Diffraction Beamline on Indus-2

    SciTech Connect

    Sinha, A. K.; Sagdeo, Archna; Gupta, Pooja; Kumar, Ashok; Singh, M. N.; Gupta, R. K.; Kane, S. R.; Deb, S. K.

    2011-07-15

    An Angle dispersive x-ray diffraction (ADXRD) beamline on bending magnet source of Indus-2 synchrotron (2.5 GeV, 300 mA) has been commissioned, for the study of single and polycrystalline samples. The beamline optics is based on vertically focusing Pt-coated pre and post mirrors and sagittal focusing Si (311) based double crystal monochromator. Experimental station consists of a six circle diffractometer equipped with scintillation detector and an image plate area detector for powder diffraction. XRD experiments have been performed to study single crystal and polycrystalline samples.