Reflectometry for Wendelstein 7-X

International Nuclear Information System (INIS)

Hirsch, M.; Holzhauer, E.; Hartfuss, H.-J.

2006-01-01

Diagnostic equipment for the fully optimized stellarator Wendelstein 7-X involves a reflectometry system dedicated to measuring edge density profiles and characterizing density perturbations and their poloidal propagation velocity. Preparatory work such as design activities and the installation of a first antenna pair belongs to the so-called start-up diagnostics. For start-up a high-directivity broadband dual antenna arrangement is proposed where the optimization of the beam waists can be decoupled from the variable sightlines, which offers flexibility for the different modes of reflectometer operation. It is shown that for large devices such as W7-X the critical value for an optimum antenna arrangement is the aperture of the first plasma facing optical element, usually a first mirror, rather than the limitations arising from the finite plasma curvature

Validation of Wendelstein 7-X fabrication and assembly stages by magnetic field calculations

International Nuclear Information System (INIS)

Andreeva, T.; Kislinger, J.

2005-01-01

The Wendelstein 7-X stellarator, which is currently under construction in Greifswald, is a 5-period machine, and many of the planned operational plasma scenarios are characterized by a rotational transform t/2p =1 at the plasma boundary. Such magnetic configurations are very sensitive to the symmetry breaking perturbations caused by fabrication and assembly errors, which can occur at different stages of the device construction. As a consequence, new islands at any periodicity can be produced, existing islands can be modified, stochastic regions can be enhanced and power load onto the divertor plates can be increased. Therefore the high precision of the machine construction is a very important issue, and evaluation of the magnetic field is necessary for the continuous validation of the fabrication and assembly stages with respect to their impact on the magnetic field perturbation. Analysis of the first fabricated winding packs (WPs) has shown that the fabrication errors can be divided into the systematical and statistical parts [1]. The systematic deviations add only negligible field components and don't perturb 5-fold symmetry of the machine, whilst the statistical deviations cause the disturbance of the machine periodicity. For that estimation of the magnetic field perturbation the numerical procedure has been developed [2], which describes statistically the randomly distributed errors, taken within the given tolerances or uses the actual measurements available as an input parameter. Since the construction of the magnet system of W7-X is subdivided into two main phases fabrication of components by industrial contractors and assembly of these components into the magnet system at the Greifswald site, the analysis of the magnetic field perturbation starts from the consideration of the impact of the WPs geometry deviations during the manufacturing stage. (Author)

Manufactoring the non-planar coils for the Wendelstein 7-X experiment

International Nuclear Information System (INIS)

Scheller, H.; Theisen, E.; Heyn, K.

2005-01-01

Because of the conditions associated with is use, nuclear fusion is a highly promising future energy supply option. The current objective of research worldwide is to demonstrate the feasibility of fusion power plants. The Wendelstein 7-X experiment at present under construction in Greifswald by the Max Planck Institute for Plasma Physics (IPP) is to demonstrate this feasibility for the stellarator concept. Babcock Noell Nuclear (BNN) in a consortium with Ansaldo Superconduttori, Genoa (ASG) has been commissioned by IPP to build the fifty superconducting non-planar coils constituting the magnet cage of the Wendelstein 7-X experiment. The coils will be assembled at the Zeitz manufacturing plant of BNM, a subsidiary of BNN. Manufacturing such a complex system is possible with the proper europeanwide network of subcontractors contributing special components. Thus, the superconductors were made by the German-Italian consortium, EAS, Hanau, and OCSI, Fornaci di Barga, Italy; the stainless steel housings are cast be Oesterby Gjutery AB in Sweden, the winding packs for BNN are produced by ABB, Neusaess, and mechanical finishing and final 3D measurement is performed by C-CON in Germany. (orig.)

Preparation for commissioning of structural sensors of Wendelstein 7-X magnet system

Energy Technology Data Exchange (ETDEWEB)

Fellinger, Joris, E-mail: joris.fellinger@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Egorov, Konstantin [ITER Organization, Route de Vinon sur Verdon, 13115 St. Paul lez Durance (France); Bykov, Victor; Schauer, Felix [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany)

2015-10-15

Highlights: • Graphical user interface for fast comparison between loads, parameter settings and models of potentially critical components of magnet system. • Fast definition of magnetic field strength limits for any electromagnetic configuration. • Definition of operational warning limits for measured signals to prevent overloading due to unexpected mechanical response of the magnet system. - Abstract: The modular stellarator Wendelstein 7-X (W7-X) in Greifswald, Germany is currently under commissioning. The magnet system (MS) consists of five symmetric modules, each one containing two flip-symmetric half modules of five non-planar and two planar superconducting coils operated in the cryostat system (CS) at 4 K. In order to validate the FE models that formed the basis of the design and the operational limits, the MS and CS were instrumented with more than 3000 sensors. The paper gives an overview of the numerical tools developed to enable safe operation of the MS based on comparisons between measured sensor signals and their FE model predictions. Output extraction from the FE models was standardized for all potentially critical components and all sensor locations. A graphical user interface (GUI) was programmed to compare critical results of different simulations and models. The GUI shows the design limit for each component. With local models, the safe design of each component was demonstrated against these design limits. The GUI also gives the degree of utilization of each component as the ratio between the calculated loads relative to the design limit. The highest degree of utilization over all components was used to define safe modes of operation and to set limits on allowed deviations of the measured signals relative to the projection before operation has to be interrupted.

Configuration Management for Wendelstein 7-X

International Nuclear Information System (INIS)

Brakel, R.; Eeten, P.v.; Hartmann, D.A.; Henkelmann, K.; Knauer, J.; Mueller, K.; Okkenga-Wolf, A.; Wenzel, U.

2009-01-01

A complex system like the large superconducting Wendelstein 7-X stellarator necessitates a dedicated organizational structure which assures permanent consistency between the requirements of its system specification and the performance attributes of all its components throughout its life time. This includes well-defined processes and centrally coordinated information structures. For this purposes the department Configuration Management (CM) has recently been established at W7-X. The detailed tasks of CM for W7-X are oriented along common CM standards and comprise configuration identification, change management, configuration status accounting and configuration verification. While the assembly of W7-X is proceeding some components are still under procurement or even under design. Thus design changes and non-conformances may have a direct impact on the assembly process. Highest priority has therefore been assigned to efficient control of change and non-conformance processes which might delay the assembly schedule.

Technology development of the soft X-ray tomography system in Wendelstein 7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Schülke, M., E-mail: mathias.schuelke@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Cardella, A.; Hathiramani, D.; Mettchen, S.; Thomsen, H.; Weißflog, S.; Zacharias, D. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany)

2013-10-15

Highlights: ► Engineering and design of soft X-ray Multi Camera Tomography System. ► Requirements of in-vessel diagnostics in Wendelstein 7-X. ► Development of internal cooling system including FEM-Analysis. ► Development of lateral shield system with testing for microwave stray radiation compatibility. ► Development of multipin feedthrough including welding qualification and leak tests. -- Abstract: The engineering and design of the soft X-ray Multi Camera Tomography System (XMCTS) in Wendelstein 7-X stellarator (W7-X) must fulfill several additional requirements compared to short pulse machines. The XMCTS has to withstand irradiation and electron cyclotron microwave loads in addition to being ultra high vacuum compatible, having low magnetic permeability and using low neutron activation materials (e.g. Co ≤ 2000 ppm). A further difficulty is the limited space inside the plasma vessel, which requires special engineering solutions. After detailed design development, supported by finite element analyses, prototypes have been manufactured and tested. At the end all test results have successfully proven that the components fulfill the requirements and that reliable and stable measurements will be possible with the XMCTS diagnostics during W7-X operation. The paper describes the design and the technological development, in particular on the electric multipin feedthrough (UHV barrier between in vessel detectors and the preamplifiers), the active cooling of the electronic components (reducing dark current/noise increase), the pneumatic shutter (protection of the detectors from sputtering and during baking) and the fiber optics illumination system (calibration of the detectors)

Absolute calibration of sniffer probes on Wendelstein 7-X

International Nuclear Information System (INIS)

Moseev, D.; Laqua, H. P.; Marsen, S.; Stange, T.; Braune, H.; Erckmann, V.; Gellert, F.; Oosterbeek, J. W.

2016-01-01

Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m 2 per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m 2 per MW injected beam power is measured.

Absolute calibration of sniffer probes on Wendelstein 7-X

Science.gov (United States)

Moseev, D.; Laqua, H. P.; Marsen, S.; Stange, T.; Braune, H.; Erckmann, V.; Gellert, F.; Oosterbeek, J. W.

2016-08-01

Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m2 per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m2 per MW injected beam power is measured.

Absolute calibration of sniffer probes on Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Moseev, D., E-mail: dmitry.moseev@ipp.mpg.de; Laqua, H. P.; Marsen, S.; Stange, T.; Braune, H.; Erckmann, V. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Gellert, F. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Ernst-Moritz-Arndt-Universität Greifswald, Greifswald (Germany); Oosterbeek, J. W. [Eindhoven University of Technology, Eindhoven (Netherlands)

2016-08-15

Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of the Wendelstein 7-X empty vacuum vessel. Normalized absolute calibration coefficients agree with the cross-calibration coefficients that are obtained by the direct measurements, indicating that the measured absolute calibration coefficients and stray radiation levels in the vessel are valid. Close to the launcher, the stray radiation in the empty vessel reaches power levels up to 340 kW/m{sup 2} per MW injected beam power. Furthest away from the launcher, i.e., half a toroidal turn, still 90 kW/m{sup 2} per MW injected beam power is measured.

Absolute calibration of sniffer probes on Wendelstein 7-X

NARCIS (Netherlands)

Moseev, D.; Laqua, H.P.; Marsen, S.; Stange, T.; Braune, H.; Erckmann, V.; Gellert, F.J.; Oosterbeek, J.W.

Here we report the first measurements of the power levels of stray radiation in the vacuum vessel of Wendelstein 7-X using absolutely calibrated sniffer probes. The absolute calibration is achieved by using calibrated sources of stray radiation and the implicit measurement of the quality factor of

Power loads in the limiter phase of Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Niemann, Holger; Jakubowski, Marcin; Sunn Pedersen, Thomas [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Wurden, Glen [Los Alamos National Laboratory, Los Alamos (United States)

2016-07-01

Wendelstein 7-X (W7-X), an advanced stellarator with five-fold symmetry, will start its initial plasma operation phase(OP1.1) in December 2015. In OP1.1 the plasma-wall interaction is realized with 5 graphite limiters installed on the inboard side of the plasma vessel, which should efficiently intercept >99% of the convective plasma heat load at the plasma edge with the chosen magnetic configuration. Assuming an even distribution of power loads among all 5 limiters, discharges with 2 MW of ECRH heating power could be run for up to a second. Calculations shows typical three separate helical magnetic flux bundles of different connection length in the order of a few tens of meters. These form 3-D structure of magnetic footprints results in localized peaks in the limiter power deposition patterns. The heterogenous temperature distribution pattern will be investigated with two IR cameras. The heat flux density will be evaluated with the THEODOR code from evolution of the surface temperature data. Together with two sets of Langmuir probes in module 5 this provides enough data to resolve experimentally different channels of heat transport towards the limiter in OP1.1 plasmas. Additionally, the obtained data will be compared against the output of EMC3-Eirene calculations to identify the channels of energy transport at the plasma boundary in the first operation phase of W7-X.

Reconstruction of magnetic configurations in W7-X using artificial neural networks

Science.gov (United States)

Böckenhoff, Daniel; Blatzheim, Marko; Hölbe, Hauke; Niemann, Holger; Pisano, Fabio; Labahn, Roger; Pedersen, Thomas Sunn; The W7-X Team

2018-05-01

It is demonstrated that artificial neural networks can be used to accurately and efficiently predict details of the magnetic topology at the plasma edge of the Wendelstein 7-X stellarator, based on simulated as well as measured heat load patterns onto plasma-facing components observed with infrared cameras. The connection between heat load patterns and the magnetic topology is a challenging regression problem, but one that suits artificial neural networks well. The use of a neural network makes it feasible to analyze and control the plasma exhaust in real-time, an important goal for Wendelstein 7-X, and for magnetic confinement fusion research in general.

Quality management for WENDELSTEIN 7-X

International Nuclear Information System (INIS)

Feist, J.-H.; Bramow, H.-J.; Braeuer, T.; Gliege, G.; Kamionka, U.; Krause, B.; Pieger-Frey, M.; Wanner, M.

2001-01-01

The WENDELSTEIN 7-X stellarator is the next step device in the stellarator line of IPP Garching and is being built in the new branch institute of IPP at Greifswald. Start of operation is scheduled for 2006. The W7-X project is presently the largest scientific project in Germany with a total spending of 300 MEU during the construction phase. From the beginning of the design up to the end of operation, the project will last for almost 40 years. More than 350 people are expected to work on W7-X during the operational phase. An experiment of this size needs an industrial type management. An essential central function within this management is performed by the quality management division. This division is responsible for the following subtasks: system co-ordination, documentation, quality planning and quality assurance. A quality system is established for the W7-X construction project which is based on the DIN EN ISO 9000 family. The basis of the quality system is a quality manual together with the necessary procedures and instructions. Quality planning and assurance is carried out in close co-operation with the various technical divisions

Physics, technologies, and status of the Wendelstein 7-X device

International Nuclear Information System (INIS)

Wagner, F.; Andreeva, T.; Baldzuhn, J.

2005-01-01

W7-X is a fully optimised low-shear stellarator of the Wendelstein line. It follows the partially optimised W7-AS device which showed excellent operational characteristics at fusion relevant parameters. W7-X is optimised along the quasi-isodynamic principle. It is built with superconducting coils and ECRF heating and plasma exhaust are developed for 30 min operation. At present, the device is at the transition from component procurement to assembly. W7-X has a high ITER relevance and it represents an excellent training bed for European industry. (author)

Studies on normal-conducting coils for Wendelstein VII-X

International Nuclear Information System (INIS)

Harmeyer, E.; Kisslinger, J.; Rau, F.; Sapper, J.; Wobig, H.

1990-08-01

For Wendelstein VII-X, the next step stellarator experiment at IPP Garching, a Helias configuration has been chosen. The goals of Wendelstein VII-X are to continue the development of the modular stellarator and to demonstrate the reactor capability of this stellarator line. The main data of the selected HS5-10 configuration with five field periods are: major radius R 0 = 5.5 m, magnetic induction B 0 = 3 T and stored magnetic energy W ≅ 0.6 GJ. For comparison with the superconducting coil system which is foreseen for Wendelstein VII-X, a pulsed water-cooled normal-conducting version has been designed in order to explore the limitations and restrictions of this approach. Limitations are the high ohmic power dissipated in the coils and the electric energy currently available at IPP. Normal-conducting coils would allow to apply the well-known techniques in manufactoring these coils, as successful in use in the Wendelstein VII-AS experiment. But these techniques are applicable also for the conductor proposed for the superconducting coils of Wendelstein VII-X. In this report the time-dependent current and resistance of the coil system circuit is considered; the electric power needed, the total dissipated energy, and the temperature rise of the coil copper is calculated. Scaling laws are derived and parameter studies are made by varying the geometrical dimensions of the system. (orig.)

Spectroscopic impurity survey in Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Buttenschoen, Birger; Burhenn, Rainer; Thomsen, Henning [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Biel, Wolfgang; Assmann, Jochen; Hollfeld, Klaus-Peter [Forschungszentrum Juelich GmbH, Juelich (Germany); Collaboration: the Wendelstein 7-X Team

2016-07-01

The High Efficiency eXtreme ultraviolet Overview Spectrometer (HEXOS) has been developed specifically for impurity identification and survey purposes on the Wendelstein 7-X stellarator. This spectrometer system, consisting of four individual spectrometers, covers the wavelength range between λ=2.5 nm and λ=160 nm, observing the intense resonance lines of relevant Mg-, Na-, Be- and Li-like impurity ions as well as the high-Z W/Ta quasi-continua. During the first operation phase of W7-X, commissioning of HEXOS was finished by providing an in-situ wavelength calibration. The permanently acquired spectra are evaluated to monitor the overall impurity content in the plasma, and serve as an indicator for unintended plasma-wall contact possibly leading to machine damage. HEXOS results from the first operation phase of W7-X are presented and discussed with respect to future scientific exploitation of the available data.

Eddy current and mechanical support of the wendelstein 7-X thermal shield

International Nuclear Information System (INIS)

Shim, S. Y.; Nagel, M.; Schauer, F.

2004-01-01

The machine which equipped huge magnet such as fusion reactor must be in need of special care on the emergency process. Rapid drop down magnetic field generate noticeable induced current, eddy current, and it causes strong electromagnetic forces on mechanical structure. The Wendelstein 7-X consists with 5 pentagonal shaped modules, plasma vessel, and each module can be divided into two symmetric half modules. Each half-module is going to be covered by 20 pieces of plasma vessel thermal shield (PVTS). The subject of this calculation is to find appropriate support positions for PVTS which can withstand self-weight of PVTS and electromagnetic force during the emergency case within our design criterion. We report the calculation procedure and results with half-module of PVTS

Major results from the first plasma campaign of the Wendelstein 7-X stellarator

NARCIS (Netherlands)

Wolf, R.C.; Ali, A.; Alonso, A.; Baldzuhn, J.; Beidler, C.; Beurskens, M.; Biedermann, C.; Bosch, H.S.; Bozhenkov, S.; Brakel, R.; Dinklage, A.; Feng, Y.; Fuchert, G.; Geiger, J.; Grulke, O.; Helander, P.; Hirsch, M.; Höfel, U.; Jakubowski, M.; Knauer, J.; Kocsis, G.; König, R.; Kornejew, P.; Kràmer-Flecken, A.; Krychowiak, M.; Landreman, M.; Langenberg, A.; Laqua, H. P.; Lazerson, S.; Maaßberg, H.; Marsen, S.; Marushchenko, M.; Moseev, D.; Niemann, H.; Pablant, N.; Pasch, E.; Rahbarnia, K.; Schlisio, G.; Stange, T.; Sunn Pedersen, T.; Svensson, J.; Szepesi, T.; Trimino Mora, H.; Turkin, Y.; Wauters, T.; Weir, G.; Wenzel, U.; Windisch, T.; Wurden, G.; Zhang, D.; Abramovic, I.; Äkàslompolo, S.; Aleynikov, P.; Aleynikova, K.; Alzbutas, R.; Anda, G.; Andreeva, T.; Ascasibar, E.; Assmann, J.; Baek, S. G.; Banduch, M.; Barbui, T.; Barlak, M.; Baumann, K.; Behr, W.; Benndorf, A.; Bertuch, O.; Biel, W.; Birus, D.; Blackwell, B.; Blanco, E.; Blatzheim, M.; Bluhm, T.; Böckenhoff, D.; Bolgert, P.; Borchardt, M.; Borsuk, V.; Boscary, J.; Böttger, L. G.; Brand, H.; Brandt, Ch; Bràuer, T.; Braune, H.; Brezinsek, S.; Brunner, K. J.; Brünner, B.; Burhenn, R.; Buttenschön, B.; Bykov, V.; Calvo, I.; Cannas, B.; Cappa, A.; Carls, A.; Carraro, L.; Carvalho, B.; Castejon, F.; Charl, A.; Chernyshev, F.; Cianciosa, M.; Citarella, R.; Ciupiński,; Claps, G.; Cole, M.; Cole, M. J.; Cordella, F.; Cseh, G.; Czarnecka, A.; Czermak, A.; Czerski, K.; Czerwinski, M.; Czymek, G.; Da Molin, A.; Da Silva, A.; Dammertz, G.; Danielson, J.; De La Pena, A.; Degenkolbe, S.; Denner, P.; Dhard, D. P.; Dostal, M.; Drevlak, M.; Drewelow, P.; Drews, Ph; Dudek, A.; Dundulis, G.; Durodie, F.; Van Eeten, P.; Effenberg, F.; Ehrke, G.; Endler, M.; Ennis, D.; Erckmann, E.; Esteban, H.; Estrada, T.; Fahrenkamp, N.; Feist, J. H.; Fellinger, J.; Fernandes, H.; Fietz, W. H.; Figacz, W.; Fontdecaba, J.; Ford, O.; Fornal, T.; Frerichs, H.; Freund, A.; Führer, M.; Funaba, T.; Galkowski, A.; Gantenbein, G.; Gao, Y.; García Regaña, J.; Garcia-Munoz, M.; Gates, D.; Gawlik, G.; Geiger, B.; Giannella, V.; Gierse, N.; Gogoleva, A.; Goncalves, B.; Goriaev, A.; Gradic, D.; Grahl, M.; Green, J.; Grosman, A.; Grote, H.; Gruca, M.; Guerard, C.; Haiduk, L.; Han, X.; Harberts, F.; Harris, J. H.; Hartfuß, H. J.; Hartmann, D.; Hathiramani, D.; Hein, B.; Heinemann, B.; Heitzenroeder, P.; Henneberg, S.; Hennig, C.; Hernandez Sanchez, J.; Hidalgo, C.; Hölbe, H.; Hollfeld, K. P.; Hölting, A.; Höschen, D.; Houry, M.; Howard, J.; Huang, X.; Huber, M.; Huber, V.; Hunger, H.; Ida, K.; Ilkei, T.; Illy, S.; Israeli, B.; Ivanov, A.; Jablonski, S.; Jagielski, J.; Jelonnek, J.; Jenzsch, H.; Junghans, P.; Kacmarczyk, J.; Kaliatka, T.; Kallmeyer, J. P.; Kamionka, U.; Karalevicius, R.; Kasahara, H.; Kasparek, W.; Kenmochi, N.; Keunecke, M.; Khilchenko, A.; Kinna, D.; Kleiber, R.; Klinger, T.; Knaup, M.; Kobarg, Th; Köchl, F.; Kolesnichenko, Y.; Könies, A.; Köppen, M.; Koshurinov, J.; Koslowski, R.; Köster, F.; Koziol, R.; Krämer, M.; Krampitz, R.; Kraszewsk, P.; Krawczyk, N.; Kremeyer, T.; Krings, Th; Krom, J.; Krzesinski, G.; Ksiazek, I.; Kubkowska, M.; Kühner, G.; Kurki-Suonio, T.; Kwak, S.; Lang, R.; Langish, S.; Laube, R.; Lechte, C.; Lennartz, M.; Leonhardt, W.; Lewerentz, L.; Liang, Y.; Linsmeier, Ch; Liu, S.; Lobsien, J. F.; Loesser, D.; Loizu Cisquella, J.; Lore, J.; Lorenz, A.; Losert, M.; Lubyako, L.; Lücke, A.; Lumsdaine, A.; Lutsenko, V.; Majano-Brown, J.; Marchuk, O.; Mardenfeld, M.; Marek, P.; Massidda, S.; Masuzaki, S.; Maurer, D.; McCarthy, K.; McNeely, P.; Meier, A.; Mellein, D.; Mendelevitch, B.; Mertens, Ph; Mikkelsen, D.; Mishchenko, O.; Missal, B.; Mittelstaedt, J.; Mizuuchi, T.; Mollen, A.; Moncada, V.; Mönnich, T.; Morizaki, T.; Munk, R.; Murakami, S.; Musielok, F.; Náfrádi, G.; Nagel, M.; Naujoks, D.; Neilson, H.; Neubauer, O.; Neuner, U.; Ngo, T.; Nocentini, R.; Nührenberg, C.; Nührenberg, J.; Obermayer, S.; Offermanns, G.; Ogawa, K.; Ongena, J.; Oosterbeek, J. W.; Orozco, G.; Otte, M.; Pacios Rodriguez, L.; Pan, W.; Panadero, N.; Panadero Alvarez, N.; Panin, A.; Papenfuß, D.; Paqay, S.; Pavone, A.; Pawelec, E.; Pelka, G.; Peng, X.; Perseo, V.; Peterson, B.; Pieper, A.; Pilopp, D.; Pingel, S.; Pisano, F.; Plaum, B.; Plunk, G.; Povilaitis, M.; Preinhaelter, J.; Proll, J.; Puiatti, M. E.; Puig Sitjes, A.; Purps, F.; Rack, M.; Récsei, S.; Reiman, A.; Reiter, D.; Remppel, F.; Renard, S.; Riedl, R.; Riemann, J.; Rimkevicius, S.; Riße, K.; Rodatos, A.; Röhlinger, H.; Romé, M.; Rong, P.; Roscher, H. J.; Roth, B.; Rudischhauser, L.; Rummel, K.; Rummel, T.; Runov, A.; Rust, N.; Ryc, L.; Ryosuke, S.; Sakamoto, R.; Samartsev, A.; Sanchez, M.; Sano, F.; Satake, S.; Satheeswaran, G.; Schacht, J.; Schauer, F.; Scherer, T.; Schlaich, A.; Schlüter, K. H.; Schmitt, J.; Schmitz, H.; Schmitz, O.; Schmuck, S.; Schneider, M.; Schneider, W.; Scholz, M.; Scholz, P.; Schrittwieser, R.; Schröder, M.; Schröder, T.; Schroeder, R.; Schumacher, H.; Schweer, B.; Shanahan, B.; Shikhovtsev, I. V.; Sibilia, M.; Sinha, P.; Siplià, S.; Skodzik, J.; Slaby, C.; Smith, H.; Spiess, W.; Spong, D. A.; Spring, A.; Stadler, R.; Standley, B.; Stephey, L.; Stoneking, M.; Stridde, U.; Sulek, Z.; Surko, C.; Suzuki, Y.; Szabó, V.; Szabolics, T.; Szökefalvi-Nagy, Z.; Tamura, N.; Terra, A.; Terry, J.; Thomas, J.; Thomsen, H.; Thumm, M.; Von Thun, C. P.; Timmermann, D.; Titus, P.; Toi, K.; Travere, J. M.; Traverso, P.; Tretter, J.; Tsuchiya, H.; Tsujimura, T.; Tulipán, S.; Turnyanskiy, M.; Unterberg, B.; Urban, J.; Urbonavicius, E.; Vakulchyk, I.; Valet, S.; Van Millingen, B.; Vela, L.; Velasco, J. L.; Vergote, M.; Vervier, M.; Vianello, N.; Viebke, H.; Vilbrandt, R.; Vorkörper, A.; Wadle, S.; Wagner, F.; Wang, E.; Wang, N.; Warmer, F.; Wegener, L.; Weggen, J.; Wei, Y.; Wendorf, J.; Werner, A.; Wiegel, B.; Wilde, F.; Winkler, E.; Winters, V.; Wolf, S.; Wolowski, J.; Wright, A.; Xanthopoulos, P.; Yamada, H.; Yamada, I.; Yasuhara, R.; Yokoyama, M.; Zajac, J.; Zarnstorff, M.; Zeitler, A.; Zhang, H.; Zhu, J.; Zilker, M.; Zimbal, A.; Zocco, A.; Zoletnik, S.; Zuin, M.

2017-01-01

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of

ArchiveDB—Scientific and technical data archive for Wendelstein 7-X

International Nuclear Information System (INIS)

Hennig, Christine; Maier, Josef; Grün, Martin; Krom, Jon; Blum, Torsten; Grahl, Michael; Heimann, Peter; Riemann, Heike; Laqua, Heike; Lewerentz, Marc; Spring, Anett; Werner, Andreas

2016-01-01

Highlights: • ArchiveDB archives all scientific and technical data of Wendelstein. • Primary index is the measured absolute time. • Continuously arising data is chunked in time for storage. • The Big Data Lambda Architecture pattern is applied. • The system is in place since a decade and a major change of underlying technology has been mastered. - Abstract: ArchiveDB is the data archive for all scientific and technical data collected at the Wendelstein 7-X project. It is a distributed system allowing continuous data archival. ArchiveDB has demanding requirements regarding performance efficiency (storage performance of 30 GB/s during experiments, expected storage amount of 1.4 PB/year), reliability (availability of 364 days/year), maintainability (testability) and portability (including change of hardware and software). Data acquisition with continuous operation and high time resolutions (up to nanoseconds scale) for physics data is supported as well as long-term recording up to 24 h/7 days for operational data (∼1 Hz rate). Moreover, all results of data analysis are stored in the archive. Another challenge, uniform retrieval of measured and analyzed data, allowing time and structure information as selection criteria, is mastered as well. The key concepts of data storage and retrieval are: (1) partitioning of incoming data in groups and stream, (2) chunking of data in boxes of manageable size covering a finite time period, and (3) indexing of data using absolute time as ordering and indexing criteria. Continuous operation of the ArchiveDB software and hardware for various systems and components relevant to Wendelstein 7-X has been done successfully for several years, thus, showing that the key requirements are satisfied. The overall data amount so far has reached 7 Terabyte over 9 years of data taking. Round-the-clock operation of the archive is in place since 5 years. Initial plasma operation OP1.1 of Wendelstein 7-X has been supported with no downtime

ArchiveDB—Scientific and technical data archive for Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Hennig, Christine, E-mail: Christine.Hennig@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Maier, Josef, E-mail: Josef.Maier@ipp.mpg.de [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Grün, Martin, E-mail: Martin.Gruen@ipp.mpg.de [FERCHAU Engineering GmbH, Steinmüllerallee 2, 51643 Gummersbach (Germany); Krom, Jon, E-mail: Jon.Krom@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Blum, Torsten, E-mail: Torsten.Bluhm@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Grahl, Michael, E-mail: Michael.Grahl@ipp.mpg.dem [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Heimann, Peter, E-mail: Peter.Heimann@ipp.mpg.de [Max Planck Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching (Germany); Riemann, Heike, E-mail: Heike.Riemann@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Laqua, Heike, E-mail: Heike.Laqua@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Lewerentz, Marc, E-mail: Marc.Lewerentz@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Spring, Anett, E-mail: Anett.Spring@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany); Werner, Andreas, E-mail: Andreas.Werner@ipp.mpg.de [Max Planck Institute for Plasma Physics, Wendelsteinstraße 1, 17491 Greifswald (Germany)

2016-11-15

Highlights: • ArchiveDB archives all scientific and technical data of Wendelstein. • Primary index is the measured absolute time. • Continuously arising data is chunked in time for storage. • The Big Data Lambda Architecture pattern is applied. • The system is in place since a decade and a major change of underlying technology has been mastered. - Abstract: ArchiveDB is the data archive for all scientific and technical data collected at the Wendelstein 7-X project. It is a distributed system allowing continuous data archival. ArchiveDB has demanding requirements regarding performance efficiency (storage performance of 30 GB/s during experiments, expected storage amount of 1.4 PB/year), reliability (availability of 364 days/year), maintainability (testability) and portability (including change of hardware and software). Data acquisition with continuous operation and high time resolutions (up to nanoseconds scale) for physics data is supported as well as long-term recording up to 24 h/7 days for operational data (∼1 Hz rate). Moreover, all results of data analysis are stored in the archive. Another challenge, uniform retrieval of measured and analyzed data, allowing time and structure information as selection criteria, is mastered as well. The key concepts of data storage and retrieval are: (1) partitioning of incoming data in groups and stream, (2) chunking of data in boxes of manageable size covering a finite time period, and (3) indexing of data using absolute time as ordering and indexing criteria. Continuous operation of the ArchiveDB software and hardware for various systems and components relevant to Wendelstein 7-X has been done successfully for several years, thus, showing that the key requirements are satisfied. The overall data amount so far has reached 7 Terabyte over 9 years of data taking. Round-the-clock operation of the archive is in place since 5 years. Initial plasma operation OP1.1 of Wendelstein 7-X has been supported with no downtime

Endoscope diagnostic for tomography, spectroscopy and thermography on Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Denner, Peter; Neubauer, Olaf; Schweer, Bernd; Liang, Yunfeng [Forschungszentrum Juelich GmbH, Institut fuer Energie- und Klimaforschung - Plasmaphysik, 52425 Juelich (Germany)

2016-07-01

Plasma-surface interaction (PSI) in the divertor region of Wendelstein 7-X (W7-X) will be of great importance for operational phase OP1.2. While the erosion of the divertor will have an impact on its lifetime and is therefore a critical subject of investigation, fundamental PSI studies in the divertor region are in many ways equally significant. These plasma-wall interactions will be influenced by impurity transport, where the complex 3D magnetic geometry will play a crucial role, but this magnetic geometry could itself be influenced by plasma effects such as Pfirsch-Schlueter and bootstrap currents. Therefore, along with measurements of obvious quantities such as heat flux, PSI research in the divertor region will also require measurements of the temperature in the plasma edge and of the concentration and distribution of different impurities, in combination with modelling of impurity transport. In order to provide the measurements necessary to address these physics questions, a set of endoscopes has been designed for visible and ultraviolet spectroscopy and tomography of the plasma edge, along with infrared thermography of the divertor tiles. An overview of this endoscope diagnostic system is presented. Details of the measurements to be taken and their relationship to physics issues such as impurity transport and erosion of the divertor are discussed.

Structural Analysis of Wendelstein 7-X: Main Results and Critical Issues

International Nuclear Information System (INIS)

Bykov, V.

2006-01-01

The goal of the Wendelstein 7-X (W7-X) stellarator project at Greifswald, Germany, is to demonstrate that the stellarator is a viable option for a fusion power-plant. The construction phase of W7-X is quite advanced, and the project has entered the assembly stage. The main W7-X structural components are the magnet system (MS) and the cryostat system, the latter comprising the outer vessel (OV), the plasma vessel (PV) and the ports. Both systems are supported by the Machine Base (MB). The W7-X '' pentagonal '' basic magnet system, composed of 50 non planar coils and 20 planar coils, is capable to generate a magnetic field up to 3 Tesla at the plasma axis. The weight of the coils and the electromagnetic (EM) loads are transferred to a central support structure by two central support elements (CSEs) per each coil. The complexity of the magnet system is caused not only by the complicated configuration of the non-planar coils, but also by contact-sliding interfaces between adjacent coils as well as between winding pack and coil cases, and by the bolted CSEs relying on flange openings. The OV and PV are interconnected by 299 ports with bellows, by the PV horizontal centering system, and by the MB via the vertical supports. Due to the large number of openings, both vessels are relatively flexible. The reliable prediction of a structural behavior of W7-X is not possible without a set of finite element (FE) models. A special strategy has been developed for the structural analysis which is under implementation now. The MS system is highly sensitive to parameter variations which is the main reason that the analysis strategy is based on completely independent FE global models (GM) realized in ANSYS, ADINA, and ABAQUS. The cryostat system ANSYS GM includes the OV, the PV, the ports with bellows, and the MB; an independent analysis of the components without taking into account their interactions would not be accurate enough. The local analyses of W7-X components are being

FE simulation of the Wendelstein 7-X cryostat system

International Nuclear Information System (INIS)

Tereshchenko, A.; Bykov, V.; Schauer, F.; Ye, M.Y.; Weissflog, S.; Andreeva, T.

2009-01-01

The purpose of the Wendelstein 7-X cryostat is to thermally insulate the magnet system (operating at cryo-temperature) by high vacuum and super insulation, to provide and enclose the working space for the plasma, and to serve as a bearing structure for the system components that have to be placed in the immediate vicinity of the plasma, such as the first wall, the divertor and some of the diagnostic devices. Concerning structural components only, the cryostat is composed of the plasma vessel, the outer vessel and the ports that interconnect the vessels. The cryostat together with the machine base comprises the so called cryostat system, and this is the system that is under consideration in this paper. Due to both the geometrical complexity and the complexity of loading, individual subsystems of the cryostat system could not be analyzed separately. For that reason, a global finite element model of the whole cryostat system had to be created. The paper presents an overview of finite element modeling, simulations with ANSYS performed on this system, and the corresponding calculation results.

Gyrokinetic analysis of linear microinstabilities for the stellarator Wendelstein 7-X

Science.gov (United States)

Xanthopoulos, P.; Jenko, F.

2007-04-01

A linear collisionless gyrokinetic investigation of ion temperature gradient (ITG) modes—considering both adiabatic and full electron dynamics—and trapped electron modes (TEMs) is presented for the stellarator Wendelstein 7-X (W7-X) [G. Grieger et al., Plasma Physics and Controlled Nuclear Fusion Research 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525]. The study of ITG modes reveals that in W7-X, microinstabilities of distinct character coexist. The effect of changes in the density gradient and temperature ratio is discussed. Substantial differences with respect to the axisymmetric geometry appear in W7-X, concerning the relative separation of regions with a large fraction of helically trapped particles and those of pronounced bad curvature. For both ITG modes and TEMs, the dependence of their linear growth rates on the background gradients is studied along with their parallel mode structure.

The procurement and testing of the stainless steel in-vessel panels of the Wendelstein 7-X Stellarator

International Nuclear Information System (INIS)

Peacock, A.; Girlinger, A.; Vorkoeper, A.; Boscary, J.; Greuner, H.; Hurd, F.; Mendelevitch, B.; Pirsch, H.; Stadler, R.; Zangl, G.

2011-01-01

320 In-vessel water cooled stainless steel panels, poloidal closure plates and pumping gap panels, covering an area of approximately 100 m 2 , are used in Wendelstein7-X to protect the plasma vessel. The panels are manufactured at Deggendorf, Germany by MAN Diesel and Turbo SE. The panels consist of a laser welded sandwich of stainless steel plates together with a labyrinth of cooling channels and have a complicated geometry to fit the plasma vessel of Wendelstein 7-X. The hydraulic and mechanical stability requirements whilst maintaining the tight tolerances for the shape of the components are very demanding. The panels are designed to operate at up to an average heat load of 100 kW/m 2 and a maximum heat load of 200 kW/m 2 with a water velocity of approximately 2 m s -1 . High heat flux testing of an un-cooled panel at a time averaged load of 200 kW/m 2 for 10 s were successfully performed to support the start up phase of Wendelstein 7-X operation. Extensive testing both during manufacture and after delivery to IPP-Garching demonstrates the suitability of the delivered panels for their purpose.

User interaction concept for plasma discharge control on WENDELSTEIN 7-X

International Nuclear Information System (INIS)

Spring, Anett; Laqua, Heike; Niedermeyer, Helmut

2006-01-01

The requirements to the user interfaces arising from the concept of segmented discharges allowing short pulses and steady state operation and from the distributed hierarchical structure of the experiment are discussed. The modular design of the user interfaces is presented including specialised tools for preparation, manipulating, and monitoring the discharge operation. The user guidance and the mapping of complex control procedures onto a physically relevant view on the plasma discharge process will be vitally important. The feasibility of the user interaction concept could already be validated on a prototype installation and during commissioning of the first technical WENDELSTEIN 7-X (W7-X) components

Overview on W7-AS results with relevance for Wendelstein 7-X and the low-shear stellarator line

International Nuclear Information System (INIS)

Wagner, F.; Anton, M.; Baldzuhn, J.

1999-01-01

The Wendelstein stellarator programme of Garching has developed low shear stellarators with successively optimised designs to remove the intrinsic deficiencies of this 3D concept. W7-X, presently under construction, is in internal terminology a fully optimised stellarator. W7-AS, the presently operated device, is a partly optimised stellarator. The optimisation of stellarators aims at improved neoclassical confinement in the long mean free path regime and improved equilibrium and stability properties. In this report, we address equilibrium, stability, turbulent and collisional energy confinement aspects (role of magnetic shear, role of the radial electric field, low and improved confinement regimes), particle transport, transport and turbulence at the plasma edge, high density operation, ECRH (OXB scheme) and ICRF heating and the development of the island divertor for exhaust. The maximal parameters achieved in W7-AS (at different discharge types) are: T e = 5.8 keV, T i = 1.5 keV, n e = 3 x 10 20 m -3 , = 2%, τ E = 50 ms. (author)

Overview on W7-AS results with relevance for WENDELSTEIN 7-X and the low-shear stellarator line

International Nuclear Information System (INIS)

Wagner, F.; Anton, M.; Baldzuhn, J.

2001-01-01

The Wendelstein stellarator programme of Garching has developed low shear stellarators with successively optimised designs to remove the intrinsic deficiencies of this 3D concept. W7-X, presently under construction, is in internal terminology a fully optimised stellarator. W7-AS, the presently operated device, is a partly optimised stellarator. The optimisation of stellarators aims at improved neoclassical confinement in the long mean free path regime and improved equilibrium and stability properties. In this report, we address equilibrium, stability, turbulent and collisional energy confinement aspects (role of magnetic shear, role of the radial electric field, low and improved confinement regimes), particle transport, transport and turbulence at the plasma edge, high density operation, ECRH (OXB scheme) and ICRF heating and the development of the island divertor for exhaust. The maximal parameters achieved in W7-AS (at different discharge types) are: T e = 5.8 keV, T i = 1.5 keV, n e = 3x10 20 m -3 , = 2%, τ E = 50 ms. (author)

Results from X-ray measurements on the Wendelstein W7-AS stellarator

Energy Technology Data Exchange (ETDEWEB)

Weller, A; Brakel, R; Burhenn, R; Hacker, H; Lazaros, A [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.)

1990-01-01

X-ray imaging measurements have contributed to studies of the plasma equilibrium, plasma fluctuations, impurity radiation and impurity transport effects in the advanced stellarator Wendelstein W7-AS (R=2 m, a=17 cm). In addition, time resolved electron temperature profiles are deduced from X-ray intensity ratios according to the two absorber foil method. The plasma is generated and heated by fundamental and 2{sup nd} harmonic ECRH (P{le}800 kW at 70 GHz). Neutral beam injection heating (P{le}1.5 MW) was applied also, assisted by D{sub 2} pellet injection. (author) 8 refs., 7 figs.

Diagnostics design for steady-state operation of the Wendelstein 7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Koenig, R.; Baldzuhn, J.; Biedermann, C.; Burhenn, R.; Bozhenkov, S.; Cantarini, J.; Dreier, H.; Endler, M.; Hartfuss, H.-J.; Hildebrandt, D.; Hirsch, M.; Jakubowski, M.; Kornejev, P.; Krychowiak, M.; Laqua, H. P.; Laux, M.; Pasch, E.; Richert, T.; Schneider, W.; Svensson, J. [Max-Planck-Institute fuer Plasmaphysik, EURATOM Association, Greifswald D-1749 (Germany); and others

2010-10-15

The status of the diagnostic developments for the quasistationary operable stellarator Wendelstein 7-X (maximum pulse length of 30 min at 10 MW ECRH heating at 140 GHz) will be reported on. Significant emphasis is being given to the issue of ECRH stray radiation shielding of in-vessel diagnostic components, which will be critical at high density operation requiring O2 and OXB heating.

Technical challenges in the construction of the steady-state stellarator Wendelstein 7-X

Czech Academy of Sciences Publication Activity Database

Bosch, H.-S.; Wolf, R.C.; Andreeva, T.; Baldzuhn, J.; Birus, D.; Bluhm, T.; Bräuer, T.; Braune, H.; Bykov, V.; Cardella, A.; Durodié, F.; Endler, M.; Erckmann, V.; Gantenbein, G.; Hartmann, D.; Hathiramani, D.; Heimann, P.; Heinemann, B.; Hennig, C.; Hirsch, M.; Holtum, D.; Jagielski, J.; Jelonnek, J.; Kasparek, W.; Klinger, T.; König, R.; Kornejew, P.; Kroiss, H.; Krom, J.G.; Kühner, G.; Laqua, H.; Laqua, H.P.; Lechte, C.; Lewerentz, M.; Maier, J.; McNeely, P.; Messiaen, A.; Michel, G.; Ongena, J.; Peacock, A.; Pedersen, T.S.; Riedl, R.; Riemann, H.; Rong, P.; Rust, N.; Schacht, J.; Schauer, F.; Schroeder, R.; Schweer, B.; Spring, A.; Stäbler, A.; Thumm, M.; Turkin, Y.; Wegener, L.; Werner, A.; Zhang, D.; Zilker, M.; Akijama, T.; Alzbutas, R.; Ascasibar, E.; Balden, M.; Banduch, M.; Baylard, Ch.; Behr, W.; Beidler, C.; Benndorf, A.; Bergmann, T.; Biedermann, C.; Bieg, B.; Biel, W.; Borchardt, M.; Borowitz, G.; Borsuk, V.; Bozhenkov, S.; Brakel, R.; Brand, H.; Brown, T.; Brucker, B.; Burhenn, R.; Buscher, K.-P.; Caldwell-Nichols, C.; Cappa, A.; Cardella, A.; Carls, A.; Carvalho, P.; Ciupinski, L.; Cole, M.; Collienne, J.; Czarnecka, A.; Czymek, G.; Dammertz, G.; Dhard, C.P.; Davydenko, V.I.; Dinklage, A.; Drevlak, M.; Drotziger, S.; Dudek, A.; Dumortier, P.; Dundulis, G.; Eeten, P.v.; Egorov, K.; Estrada, T.; Faugel, H.; Fellinger, J.; Feng, Y.; Fernandes, H.; Fietz, W.H.; Figacz, W.; Fischer, F.; Fontdecaba, J.; Freund, A.; Funaba, T.; Fünfgelder, H.; Galkowski, A.; Gates, D.; Giannone, L.; García Regana, J.M.; Geiger, J.; Geißler, S.; Greuner, H.; Grahl, M.; Groß, S.; Grosman, A.; Grote, H.; Grulke, O.; Haas, M.; Haiduk, L.; Hartfuß, H.-J.; Harris, J.H.; Haus, D.; Hein, B.; Heitzenroeder, P.; Helander, P.; Heller, R.; Hidalgo, C.; Hildebrandt, D.; Höhnle, H.; Holtz, A.; Holzhauer, E.; Holzthüm, R.; Huber, A.; Hunger, H.; Hurd, F.; Ihrke, M.; Illy, S.; Ivanov, A.; Jablonski, S.; Jaksic, N.; Jakubowski, M.; Jaspers, R.; Jensen, H.; Jenzsch, H.; Kacmarczyk, J.; Kaliatk, T.; Kallmeyer, J.; Kamionka, U.; Karaleviciu, B.; Kern, S.; Keunecke, M.; Kleiber, R.; Knauer, J.; Koch, R.; Kocsis, G.; Könies, A.; Köppen, M.; Koslowski, R.; Koshurinov, J.; Krämer-Flecken, A.; Krampitz, R.; Kravtsov, Y.; Krychowiak, M.; Krzesinski, G.; Ksiazek, I.; Kubkowska, Fr.; Kus, A.; Langish, S.; Laube, R.; Laux, M.; Lazerson, S.; Lennartz, M.; Li, C.; Lietzow, R.; Lohs, A.; Lorenz, A.; Louche, F.; Lubyako, L.; Lumsdaine, A.; Lyssoivan, A.; Maaßberg, H.; Marek, P.; Martens, C.; Marushchenko, N.; Mayer, M.; Mendelevitch, B.; Mertens, Ph.; Mikkelsen, D.; Mishchenko, A.; Missal, B.; Mizuuchi, T.; Modrow, H.; Mönnich, T.; Morizaki, T.; Murakami, S.; Musielok, F.; Nagel, M.; Naujoks, D.; Neilson, H.; Neubauer, O.; Neuner, U.; Nocentini, R.; Noterdaeme, J.-M.; Nührenberg, C.; Obermayer, S.; Offermanns, G.; Oosterbeek, H.; Otte, M.; Panin, A.; Pap, M.; Paquay, S.; Pasch, E.; Peng, X.; Petrov, S.; Pilopp, D.; Pirsch, H.; Plaum, B.; Pompon, F.; Povilaitis, M.; Preinhaelter, Josef; Prinz, O.; Purps, F.; Rajna, T.; Récsei, S.; Reiman, A.; Reiter, D.; Remmel, J.; Renard, S.; Rhode, V.; Riemann, J.; Rimkevicius, S.; Riße, K.; Rodatos, A.; Rodin, I.; Romé, M.; Roscher, H.-J.; Rummel, K.; Rummel, Th.; Runov, A.; Ryc, L.; Sachtleben, J.; Samartsev, A.; Sanchez, M.; Sano, F.; Scarabosio, A.; Schmid, M.; Schmitz, H.; Schmitz, O.; Schneider, M.; Schneider, W.; Scheibl, L.; Scholz, M.; Schröder, G.; Schröder, M.; Schruff, J.; Schumacher, H.; Shikhovtsev, I.V.; Shoji, M.; Siegl, G.; Skodzik, J.; Smirnow, M.; Speth, E.; Spong, D.A.; Stadler, R.; Sulek, Z.; Szabó, V.; Szabolics, T.; Szetefi, T.; Szökefalvi-Nagy, Z.; Tereshchenko, A.; Thomsen, H.; Thumm, M.; Timmermann, D.; Tittes, H.; Toi, K.; Tournianski, M.; Toussaint, U.v.; Tretter, J.; Tulipán, S.; Turba, P.; Uhlemann, R.; Urban, Jakub; Urbonavicius, E.; Urlings, P.; Valet, S.; Van Eester, D.; Van Schoor, M.; Vervier, M.; Viebke, H.; Vilbrandt, R.; Vrancken, M.; Wauters, T.; Weissgerber, M.; Weiß, E.; Weller, A.; Wendorf, J.; Wenzel, U.; Windisch, T.; Winkler, E.; Winkler, M.; Wolowski, J.; Wolters, J.; Wrochna, G.; Xanthopoulos, P.; Yamada, H.; Yokoyama, M.; Zacharias, D.; Zajac, Jaromír; Zangl, G.; Zarnstorff, M.; Zeplien, H.; Zoletnik, S.; Zuin, M.

2013-01-01

Roč. 53, č. 12 (2013), s. 126001-126001 ISSN 0029-5515 Institutional support: RVO:61389021 Keywords : plasma * stellarator * technology * diagnostics * data acquisition * Wendelstein 7-X * electron cyclotron heating * electron Bernstein wave Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.243, year: 2013 http://iopscience.iop.org/0029-5515/53/12/126001/article

The procurement and testing of the stainless steel in-vessel panels of the Wendelstein 7-X Stellarator

Energy Technology Data Exchange (ETDEWEB)

Peacock, A., E-mail: alan.peacock@ipp.mpg.de [European Commission c/o Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany); Girlinger, A. [MAN Diesel and Turbo SE D-94469 Deggendorf (Germany); Vorkoeper, A. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 17491 Greifswald (Germany); Boscary, J.; Greuner, H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany); Hurd, F. [European Commission c/o Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany); Mendelevitch, B.; Pirsch, H.; Stadler, R.; Zangl, G. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, 85748 Garching (Germany)

2011-10-15

320 In-vessel water cooled stainless steel panels, poloidal closure plates and pumping gap panels, covering an area of approximately 100 m{sup 2}, are used in Wendelstein7-X to protect the plasma vessel. The panels are manufactured at Deggendorf, Germany by MAN Diesel and Turbo SE. The panels consist of a laser welded sandwich of stainless steel plates together with a labyrinth of cooling channels and have a complicated geometry to fit the plasma vessel of Wendelstein 7-X. The hydraulic and mechanical stability requirements whilst maintaining the tight tolerances for the shape of the components are very demanding. The panels are designed to operate at up to an average heat load of 100 kW/m{sup 2} and a maximum heat load of 200 kW/m{sup 2} with a water velocity of approximately 2 m s{sup -1}. High heat flux testing of an un-cooled panel at a time averaged load of 200 kW/m{sup 2} for 10 s were successfully performed to support the start up phase of Wendelstein 7-X operation. Extensive testing both during manufacture and after delivery to IPP-Garching demonstrates the suitability of the delivered panels for their purpose.

Collective Thomson scattering data analysis for Wendelstein 7-X

DEFF Research Database (Denmark)

Abramovic, I.; Pavone, A.; Svensson, J.

2017-01-01

Collective Thomson scattering (CTS) diagnostic is being installed on the Wendelstein 7-X stellarator to measure the bulk ion temperature in the upcoming experimental campaign. In order to prepare for the data analysis, a forward model of the diagnostic (eCTS) has been developed and integrated...... into the Bayesian data analysis framework Minerva. Synthetic spectra have been calculated with the forward model and inverted using Minerva in order to demonstrate the feasibility to measure the ion temperature in the presence of nuisance parameters that also influence CTS spectra. In this paper we report...... on the results of this anlysis and discuss the main sources of uncertainty in the CTS data analysis....

Project management lessons learned from building the Wendelstein 7-x stellerator fusion research reactor

Energy Technology Data Exchange (ETDEWEB)

Freire-Gormaly, M.; Gittens, A.; Zhang, L., E-mail: m.freire.gormaly@utoronto.ca, E-mail: antonio.gittens@mail.utoronto.ca, E-mail: lavender.zhang@outlook.com [University of Toronto, Toronto, ON (Canada)

2015-07-01

Wendelstein 7-X (W7-X) is the world's largest 'stellerator' nuclear fusion reactor being commissioned in Greifswald, Germany. It will inform the international fusion energy test device (ITER). The complexity of W7- X added challenges since industrial expertise to manufacture components did not exist. The construction was completed eight years behind schedule and almost 100% over budget. Key take-away lessons in project management were revealed from W7-X which can be applied to any nuclear project. These lessons are aligned with the project management knowledge areas of schedule, stakeholder, procurement, scope, schedule, cost, communication, risk, quality, human resources and procurement management. (author)

Project management lessons learned from building the Wendelstein 7-x stellerator fusion research reactor

International Nuclear Information System (INIS)

Freire-Gormaly, M.; Gittens, A.; Zhang, L.

2015-01-01

Wendelstein 7-X (W7-X) is the world's largest 'stellerator' nuclear fusion reactor being commissioned in Greifswald, Germany. It will inform the international fusion energy test device (ITER). The complexity of W7- X added challenges since industrial expertise to manufacture components did not exist. The construction was completed eight years behind schedule and almost 100% over budget. Key take-away lessons in project management were revealed from W7-X which can be applied to any nuclear project. These lessons are aligned with the project management knowledge areas of schedule, stakeholder, procurement, scope, schedule, cost, communication, risk, quality, human resources and procurement management. (author)

MobileCoDaC – A transportable control, data acquisition and communication infrastructure for Wendelstein 7-X

International Nuclear Information System (INIS)

Hennig, Christine; Bluhm, Torsten; Kühner, Georg; Laqua, Heike; Lewerentz, Marc; Müller, Ina; Pingel, Steffen; Riemann, Heike; Schacht, Jörg; Spring, Anett; Werner, Andreas; Wölk, Andreas

2014-01-01

Highlights: • MobileCoDaC is a transportable CoDaC infrastructure for Wendelstein 7-X. • It allows in situ testing and commissioning of components to be used at W7-X by providing W7-X CoDaC infrastructure. • It has been used successfully for test and commissioning of the HEXOS diagnostic at Forschungszentrum Jülich. - Abstract: MobileCoDaC is a test bed allowing in situ testing and commissioning the control and data acquisition of components to be operated at Wendelstein 7-X. It is a minimized replica of the functionality of the complete W7-X CoDaC infrastructure and can be operated independently. MobileCoDaC contains a set of W7-X CoDaC servers, network infrastructure, and accessories for remote access. All hardware is mounted in a single transportable rack system. Moreover, it provides the software infrastructure and user applications for experiment preparation, experiment operation, trouble shooting and experiment data access. MobileCoDaC has been operated successfully for test and commissioning of the control and data acquisition of the HEXOS (high efficiency extreme ultraviolet overview spectrometer) diagnostic at Forschungszentrum Jülich

FEM analysis of mechanical behaviour of coil support connections in Wendelstein 7-X fusion reactor

International Nuclear Information System (INIS)

Krzesinski, G.; Zagrajek, T.; Marek, P.; Dobosz, R.; Czarkowski, P.; Kurzydlowski, K.J.

2006-01-01

The objective of Wendelstein 7-X project is the stellarator-type fusion reactor. In this device plasma channel is under control of magnetic field coming from magnet system of very complicated shape, made of 70 superconducting coils symmetrically arranged in 5 identical sections. Every coil is connected to central ring with two extensions which transfer loads resulting from electromagnetic field and gravity. The aim of this work was to analyse mechanical behaviour of the bolted connections using detailed 3D finite element models. All simulations were performed assuming elasto-plastic behaviour of the materials, assembly stresses and friction contacts between different parts of the connections. Stress distributions, displacements, forces acting on the bolts and welds were studied using standard and submodeling routines. The results were subsequently used to optimize the design of critical central support elements. (author)

Results from X-ray measurements on the Wendelstein W7-AS stellarator

International Nuclear Information System (INIS)

Weller, A.; Brakel, R.; Burhenn, R.; Hacker, H.; Lazaros, A.

1991-01-01

X-ray imaging measurements have contributed to studies of the plasma equilibrium, plasma fluctuations, impurity radiation and impurity transport effects in the advanced stellarator Wendelstein W7-AS (R = 2 m, a = 17 cm). In addition, time resolved electron temperature profiles are deduced from X-ray intensity ratios according to the two absorber foil method. The plasma is generated and heated by fundamental and 2nd harmonic ECRH (P ≤ 800 kW at 70 GHz). Neutral beam injection heating (P ≤ 1.5 MW) was applied also, assisted by D 2 pellet injection. (orig.)

The steady-state ECRH-system at Wendelstein7-X

International Nuclear Information System (INIS)

Laqua, H.P.; Erckmann, V.; Brakel, R.; Braune, H.; Maassberg, H.; Marushchenko, N.; Michel, G.; Turkin, Y.; Ullrich, S.; Dammertz, G.; Thumm, M.; Brand, P.; Gantenbein, G.; Kasparek, W.

2005-01-01

Electron Cyclotron Resonance Heating (ECRH) is the main heating system for the Wendelstein7-X (W7-X) stellarator and the only one for CW-operation in the first stage. The mission of W7-X, which is presently under construction at IPP-Greifswald, is to demonstrate the inherent steady state capability of stellarators at reactor relevant plasma parameters. A modular 10 MW ECRH plant at 140 GHz with 1 MW CW-capability power for each module is under construction to meet the scientific objectives. Simulations of different ECRH scenarios, which are foreseen for W7-X operation and base on ray- tracing calculations and confinement studies, will be presented. A steady state ECRH has specific requirements on the stellarator machine itself, on the ECRH-sources, transmissions elements and on the experimental environment. In particular all elements have to be sufficiently cooled, screened and armoured against microwaves. The commissioning of the ECRH plant is well under way, the strategy and status of the project will be reported. First full power, CW integral tests of one ECRH module have been performed. A large microwave stray radiation chamber for integrated in-vessel component tests had been brought into operation. A bi-axially movable, motor driven ECRH antenna mock-up was build and is tested for reliability now. A strategy for the commissioning and the first experimental campaign at W7-X has been developed. (author)

Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

NARCIS (Netherlands)

Peng, X.B.; Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F.; Vliegenthart, W.A.

2014-01-01

A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the

Design and manufacturing status of trim coils for the Wendelstein 7-X stellarator experiment

Energy Technology Data Exchange (ETDEWEB)

Riße, K., E-mail: konrad.risse@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Rummel, Th.; Freundt, S.; Dudek, A.; Renard, S.; Bykov, V.; Köppen, M. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Langish, S.; Neilson, G.H.; Brown, Th.; Chrzanowski, J.; Mardenfeld, M.; Malinowski, F.; Khodak, A.; Zhao, X. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Eksaa, G. [Everson Tesla Inc., Nazareth, PA (United States)

2013-10-15

Highlights: ► The trim coil system will fine tune the main magnetic field during plasma operation by reducing the magnetic field errors. ► The coil design and operational parameters are fixed, the manufacturing is running. ► The coils are equipped with temperature sensors and a voltage tap system to monitor the coil temperature. ► The max. operational deflection is in the order of 4.5 mm; the max. shearing stress across bond planes is of order 16 MPa. ► Special clamps equipped with elastomeric pads allow fixing the coils on the outer cryostat wall. -- Abstract: The stellarator fusion experiment Wendelstein 7-X (W7-X) is currently under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald, Germany. The main magnetic field will be provided by a superconducting magnet system which generates a fivefold toroidal periodic magnetic field. However, unavoidable tolerances can result in small deviations of the magnetic field which disturb the toroidal periodicity. In order to have a tool to influence these field errors five additional normal conducting trim coils were designed to allow fine tuning of the main magnetic field during plasma operation. In the frame of an international cooperation the trim coils will be contributed by the US partners. Princeton Plasma Physics Laboratory has accomplished several tasks to develop the final design ready for manufacturing e.g. detailed manufacturing design for the winding and for the coil connection area. The design work was accompanied by a detailed analysis of resulting forces and moments to prove the design. The manufacturing of the coils is running at Everson Tesla Inc; the first two coils were received at IPP.

Quality Management for WENDELSTEIN 7-X - Lessons learned

International Nuclear Information System (INIS)

Feist, J.-H.

2006-01-01

At the Max-Planck-Institut fuer Plasmaphysik (IPP) in Greifswald (Germany) a new fusion experiment of the Stellarator type, the WENDELSTEIN 7-X (W7-X), is currently being constructed. Assembly of W7-X has recently started and will last for the next five years, followed by one year of commissioning. The construction team at Greifswald amounts to more than 300 people. The manufacture of the components for W7-X is spread over whole Europe at more than 50 companies. For this project a Quality Management System based on the ISO 9000ff family has been established, adapted to the special needs of a scientific organisation in a public environment. It takes into account two important differences compared to normal industrial production: only one device is built ('' prototype work '') and the compact de-sign does, in general, not allow later modifications or repair work on the magnet system and some other core components. The QM-System has been described at the 21 st SOFT. Although all members of the project want to produce quality the compliance with the regulations of the QM-system is sometimes regarded as an obstacle for the work. Therefore one main aspect of QM is to implement the main features of QM like con-trol of all processes, documentation, traceability and technical soundness of the experiment without jeopardising the flow of work. For the manufacture of the components a very important document is the technical specification. It must clearly outline all properties of the product, the standards to be applied, the qualification of production processes (e.g. soldering, welding, electrical insulation), tests for the verification and, very important, the need for a clear structured documentation to allow traceability. During the course of the contract the handling of changes and non-conformities is a very important issue from the QM point of view. Here one has to balance the interests of both sides which inevitably lead to the problem of optimizing the process with

The Thomson scattering system at Wendelstein 7-X

Science.gov (United States)

Pasch, E.; Beurskens, M. N. A.; Bozhenkov, S. A.; Fuchert, G.; Knauer, J.; Wolf, R. C.

2016-11-01

This paper describes the design of the Thomson scattering system at the Wendelstein 7-X stellarator. For the first operation campaign we installed a 10 spatial channel system to cover a radial half profile of the plasma cross section. The start-up system is based on one Nd:YAG laser with 10 Hz repetition frequency, one observation optics, five fiber bundles with one delay line each, and five interference filter polychromators with five spectral channels and silicon avalanche diodes as detectors. High dynamic range analog to digital converters with 14 bit, 1 GS/s are used to digitize the signals. The spectral calibration of the system was done using a pulsed super continuum laser together with a monochromator. For density calibration we used Raman scattering in nitrogen gas. Peaked temperature profiles and flat density profiles are observed in helium and hydrogen discharges.

Data access and its implementation at Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Bluhm, T. [Max-Planck-Institute fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany)], E-mail: torsten.bluhm@ipp.mpg.de; Heimann, P. [Max-Planck-Institute fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Hennig, Ch. [Max-Planck-Institute fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Kroiss, H. [Max-Planck-Institute fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Kuehner, G. [Max-Planck-Institute fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Maier, J. [Max-Planck-Institute fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Riemann, H. [Max-Planck-Institute fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstr. 1, 17491 Greifswald (Germany); Zilker, M. [Max-Planck-Institute fuer Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

2008-04-15

The increasing number of data acquisition stations and setups in laboratory environments at Wendelstein 7-X does already produce a considerable amount of data by now. Diagnosticians want to view the acquired data in a comfortable way and use them for calculations in their own test and analysis algorithms. To prepare for full operation of W7-X, a reasonable approach is to provide data access methods that stay as close as possible to the final data access concept. This requires taking care of the special needs of W7-X regarding continuously acquired data, segment based parameter switching and synchronization of data from different diagnostics. Therefore, a data access interface has been designed and implemented considering continuous data acquisition as well as usability and performance issues. The interface and its usage in different software environments (e.g. high level scientific programming languages) will be explained. Also, the integration of user defined off line analysis algorithms will be described. Additionally, the DataBrowser will be presented. The DataBrowser is a Java application that can browse continuously acquired data of different kind, provides several types of plots including zooming functions to display the data and the corresponding parameters and offers export functions to save selected data locally.

Performance and properties of the first plasmas of Wendelstein 7-X

Science.gov (United States)

Klinger, T.; Alonso, A.; Bozhenkov, S.; Burhenn, R.; Dinklage, A.; Fuchert, G.; Geiger, J.; Grulke, O.; Langenberg, A.; Hirsch, M.; Kocsis, G.; Knauer, J.; Krämer-Flecken, A.; Laqua, H.; Lazerson, S.; Landreman, M.; Maaßberg, H.; Marsen, S.; Otte, M.; Pablant, N.; Pasch, E.; Rahbarnia, K.; Stange, T.; Szepesi, T.; Thomsen, H.; Traverso, P.; Velasco, J. L.; Wauters, T.; Weir, G.; Windisch, T.; The Wendelstein 7-X Team

2017-01-01

The optimized, superconducting stellarator Wendelstein 7-X went into operation and delivered first measurement data after 15 years of construction and one year commissioning. Errors in the magnet assembly were confirmend to be small. Plasma operation was started with 5 MW electron cyclotron resonance heating (ECRH) power and five inboard limiters. Core plasma values of {{T}\\text{e}}>8 keV, {{T}\\text{i}}>2 keV at line-integrated densities n≈ 3\\centerdot {{10}19}~{{\\text{m}}-2} were achieved, exceeding the original expectations by about a factor of two. Indications for a core-electron-root were found. The energy confinement times are in line with the international stellarator scaling, despite unfavourable wall conditions, i.e. large areas of metal surfaces and particle sources from the limiter close to the plasma volume. Well controlled shorter hydrogen discharges at higher power (4 MW ECRH power for 1 s) and longer discharges at lower power (0.7 MW ECRH power for 6 s) could be routinely established after proper wall conditioning. The fairly large set of diagnostic systems running in the end of the 10 weeks operation campaign provided first insights into expected and unexpected physics of optimized stellarators.

Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited)

NARCIS (Netherlands)

Krychowiak, M.; Adnan, A.; Alonso, A.; Andreeva, T.; Baldzuhn, J.; Barbui, T.; Beurskens, Marc N.A.; Biel, W.; Biedermann, C.; Blackwell, B.D.; Bosch, H.S.; Bozhenkov, S.; Brakel, R.; Bräuer, T.; Brotas de Carvalho, B.; Burhenn, R.; Buttenschön, B.; Cappa, A.; Cseh, G.; Czarnecka, A.; Dinklage, A.; Drews, P.; Dzikowicka, A.; Effenberg, F.; Endler, M.; Erckmann, V.; Estrada, T.; Ford, O.; Fornal, T.; Frerichs, H.; Fuchert, G.; Geiger, J.; Grulke, O.; Harris, J.H.; Hartfuß, H.J.; Hartmann, D.; Hathiramani, D.; Hirsch, M.; Höfel, U.; Jabłoński, S.; Jakubowski, M.W.; Kaczmarczyk, J.; Klinger, T.; Klose, S.; Knauer, J.; Kocsis, G.; König, R.; Kornejew, P.; Krämer-Flecken, A.; Krawczyk, N.; Kremeyer, T.; Ksiazek, I.; Kubkowska, M.; Langenberg, A.; Laqua, H.P.; Laux, M.; Lazerson, S.; Liang, Y.; Liu, S.C.; Lorenz, A.; Marchuk, A.O.; Marsen, S.; Moncada, V.; Naujoks, D.; Neilson, H.; Neubauer, O.; Neuner, U.; Niemann, H.; Oosterbeek, J.W.; Otte, M.; Pablant, N.; Pasch, E.; Sunn Pedersen, T.; Pisano, F.; Rahbarnia, K.; Ryć, L.; Schmitz, O.; Schmuck, S.; Schneider, W.; Schröder, T.; Schuhmacher, H.; Schweer, B.; Standley, B.; Stange, T.; Stephey, L.; Svensson, J.; Szabolics, T.; Szepesi, T.; Thomsen, H.; Travère, J.M.; Trimino Mora, H.; Tsuchiya, H.; Weir, G.M.; Wenzel, U.; Werner, A.; Wiegel, B.; Windisch, T.; Wolf, R.; Wurden, G.A.; Zhang, D.; Zimbal, A.; Zoletnik, S.

2016-01-01

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent

Runtime resource checking at WENDELSTEIN 7-X during plasma operation

International Nuclear Information System (INIS)

Laqua, H.

2006-01-01

The super conducting stellarator WENDELSTEIN 7-X (W7-X) will run pulses of up to 30 minutes duration. All discharge scenarios compatible with these capabilities will be supported by the control system: short pulses with arbitrary intervals, steady state discharges and arbitrary sequences of phases with different characteristics in one discharge. Long discharges with phases of different characteristics are understood as series of short discharge sections called '' segments ''. This, the heart of the control system is the '' segment control ''. Due to the long pulses and the innovative nature of plasma components a failure of a component during a discharge cannot be ruled out and has to be handled by the control system. Safety critical failures are handled by the safety system. In many cases the failure leads only to a degradation of the plasma quality and not to a safety critical situation. The segment control must detect the situation and steer the discharge into another state in which preferably the discharge can continue without the failed component or the discharge is gracefully brought to an end. Therefore the segment control system provides an online resource check of all components included in the segment control system. The rules of the resource check depend on the planned plasma characteristics given in the segment description, e.g. when not all heating systems are needed for the planned scenario a failure in an unneeded heating system will be tolerated. According to the hierarchical architecture of the segment control system described in [Laqua, H.; Niedermeyer, H.; Schacht, J.: Control System of Wendelstein 7-X Experiment. Fusion Engineering and Design 66-68, 669-673 (2003)] runtime resource checking is accomplished hierarchically, too. A system on a certain level in the hierarchy evaluates the feasibility of the physical characteristic demanded from this system to process this segment. Together with the feasibility information passed to this system by

Major results from the first plasma campaign of the Wendelstein 7-X stellarator.

Czech Academy of Sciences Publication Activity Database

Wolf, R.C.; Preinhaelter, Josef; Urban, Jakub; Zajac, Jaromír

2017-01-01

Roč. 57, č. 10 (2017), č. článku 102020. ISSN 0029-5515 EU Projects: European Commission(XE) 633053 - EUROfusion Institutional support: RVO:61389021 Keywords : plasma * stellarator * technology * diagnostics * data acquisition * Wendelstein 7-X * electron cyclotron heating * electron Bernstein wave Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/10.1088/1741-4326/aa770d

Coupled FEM-DBEM method to assess crack growth in magnet system of Wendelstein 7-X

Directory of Open Access Journals (Sweden)

R. Citarella

2013-10-01

Full Text Available The fivefold symmetric modular stellarator Wendelstein 7-X (W7-X is currently under construction in Greifswald, Germany. The superconducting coils of the magnet system are bolted onto a central support ring and interconnected with five so-called lateral support elements (LSEs per half module. After welding of the LSE hollow boxes to the coil cases, cracks were found in the vicinity of the welds that could potentially limit the allowed number N of electromagnetic (EM load cycles of the machine. In response to the appearance of first cracks during assembly, the Stress Intensity Factors (SIFs were calculated and corresponding crack growth rates of theoretical semi-circular cracks of measured sizes in potentially critical position and orientation were predicted using Paris’ law, whose parameters were calibrated in fatigue tests at cryogenic temperature. In this paper the Dual Boundary Element Method (DBEM is applied in a coupled FEM-DBEM approach to analyze the propagation of multiple cracks with different shapes. For this purpose, the crack path is assessed with the Minimum Strain Energy density criterion and SIFs are calculated by the J-integral approach. The Finite Element Method (FEM is adopted to model, using the commercial codes Ansys or Abaqus;, the overall component whereas the submodel analysis, in the volume surrounding the cracked area, is performed by FEM (“FEM-FEM approach” or alternatively by DBEM (“FEM-DBEM approach”. The “FEM-FEM approach” considers a FEM submodel, that is extracted from the FEM global model; the latter provide the boundary conditions for the submodel. Such approach is affected by some restrictions in the crack propagation phase, whereas, with the “FEM-DBEM approach”, the crack propagation simulation is straightforward. In this case the submodel is created in a DBEM environment with boundary conditions provided by the global FEM analysis; then the crack is introduced and a crack propagation analysis

Optical design study of an infrared visible viewing system for Wendelstein 7-X divertor observation and control

NARCIS (Netherlands)

Cantarini, J.; Hildebrandt, D.; König, R.; Klinkhamer, J.F.F.; Moddemeijer, K.; Vliegenthart, W.A.; Wolf, R.

2008-01-01

For the Wendelstein 7-X stellarator, which will allow quasicontinuous operation (τ30 min) with 10 MW of electron cyclotron radiation heating power, a conceptual design study for an IR/visible viewing system (IVVS) has been elaborated. Ten such systems, as part of the machine protection system, will

Continuous data acquisition with online analysis for the Wendelstein 7-X magnetic diagnostics

International Nuclear Information System (INIS)

Hennig, Ch.; Werner, A.; Marquardt, M.; Bluhm, T.; Kroiss, H.; Kuehner, G.; Heimann, P.; Maier, J.; Riemann, H.; Zilker, M.

2008-01-01

The coupling of continuous data acquisition and continuous online analysis keeping up with the acquisition is one of the features the W7-X data acquisition system is designed for. As proof of principle of this concept the magnetic diagnostics have been implemented. The magnetic diagnostics measure time derivatives of the magnetic fluxes and the signals have to be time integrated accordingly. Both measurement and analysis tasks are executed on a single PC based system. The configuration of both hard- and software of the system is presented. Special focuses are the task of software integration of a user supplied online analysis function into the data acquisition system and the incorporation of the complete system into the W7-X segment concept in use by the control system. The complete installation has been tested at the WEGA Stellarator experiment. Because WEGA is capable of continuous steady state plasma operation the practical suitability of the installation for W7-X could be demonstrated successfully

Reconstruction of recycling flux from synthetic camera images, evaluated for the Wendelstein 7-X startup limiter

Science.gov (United States)

Frerichs, H.; Effenberg, F.; Feng, Y.; Schmitz, O.; Stephey, L.; Reiter, D.; Börner, P.; The W7-X Team

2017-12-01

The interpretation of spectroscopic measurements in the edge region of high-temperature plasmas can be guided by modeling with the EMC3-EIRENE code. A versatile synthetic diagnostic module, initially developed for the generation of synthetic camera images, has been extended for the evaluation of the inverse problem in which the observable photon flux is related back to the originating particle flux (recycling). An application of this synthetic diagnostic to the startup phase (inboard) limiter in Wendelstein 7-X (W7-X) is presented, and reconstruction of recycling from synthetic observation of \\renewcommand{\

Status of the diagnostics development for the first operation phase of the stellarator Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

König, R., E-mail: rlk@ipp.mpg.de; Biedermann, C.; Burhenn, R.; Endler, M.; Grulke, O.; Hathiramani, D.; Hirsch, M.; Jakubowski, M.; Kornejew, P.; Krychowiak, M.; Langenberg, A.; Laux, M.; Lorenz, A.; Otte, M.; Pasch, E.; Pedersen, T. S.; Schneider, W.; Thomsen, H.; Windisch, T.; Zhang, D. [Max Planck Institute for Plasma Physics, 17491 Greifswald (Germany); and others

2014-11-15

An overview of the diagnostics which are essential for the first operational phase of Wendelstein 7-X and the set of diagnostics expected to be ready for operation at this time are presented. The ongoing investigations of how to cope with high levels of stray Electron Cyclotron Resonance Heating (ECRH) radiation in the ultraviolet (UV)/visible/infrared (IR) optical diagnostics are described.

Tasks and structure of the WENDELSTEIN 7-X control system

International Nuclear Information System (INIS)

Schacht, Joerg; Niedermeyer, Helmut; Laqua, Heike; Spring, Anett; Mueller, Ina; Pingel, Steffen; Woelk, Andreas

2006-01-01

The super conducting stellarator WENDELSTEIN 7-X will run pulses of up to 30 min duration with full heating power. Short pulses with arbitrary intervals, steady state long discharges and arbitrary sequences of short phases with different characteristics in one discharge will be supported by the control system. Each technical component and each diagnostic system including its data acquisition will have its own control system permitting autonomous operation for commissioning and testing. During the experimental sessions the activity of these devices will be coordinated by a central control system and the machine runs more or less automatically with predefined programs. A session leader program allows the leader of the experiment to choose and chain predefined segments, to start or stop a segment chain as a discharge. The progress of the discharge is shown by a sequence monitor attached to the central sequence controller and the session leader program. W7-X has to be prepared for the experiment and monitored by means of the PLC based operational management system. A safety system working independently of the operational management consists of local units responsible for the safety of each component and a central unit ensuring the safety of the whole W7-X system. This safety system provides interlocks and controls the human access to the device. A safety analysis is the basis for the development of the safety system

Experimental investigation of the ECRH stray radiation during the start-up phase in Wendelstein 7-X

Science.gov (United States)

Moseev, Dmitry; Laqua, Heinrich; Marsen, Stefan; Stange, Torsten; Braune, Harald; Erckmann, Volker; Gellert, Florian; Oosterbeek, Johann Wilhelm; Wenzel, Uwe

2017-07-01

Electron cyclotron resonance heating (ECRH) is the main heating mechanism in the Wendelstein 7-X stellarator (W7-X). W7-X is equipped with five absolutely calibrated sniffer probes that are installed in each of the five modules of the device. The sniffer probes monitor energy flux of unabsorbed ECRH radiation in the device and interlocks are fed with the sniffer probe signals. The stray radiation level in the device changes significantly during the start-up phase: plasma is a strong microwave absorber and during its formation the stray radiation level in sniffer probes reduces by more than 95%. In this paper, we discuss the influence of neutral gas pressure and gyrotron power on plasma breakdown processes.

Experimental results of near real-time protection system for plasma facing components in Wendelstein 7-X at GLADIS

Science.gov (United States)

Ali, A.; Jakubowski, M.; Greuner, H.; Böswirth, B.; Moncada, V.; Sitjes, A. Puig; Neu, R.; Pedersen, T. S.; the W7-X Team

2017-12-01

One of the aims of stellarator Wendelstein 7-X (W7-X), is to investigate steady state operation, for which power exhaust is an important issue. The predominant fraction of the energy lost from the confined plasma region will be absorbed by an island divertors, which is designed for 10 {{MWm}}-2 steady state operation. In order to protect the divertor targets from overheating, 10 state-of-the-art infrared endoscopes will be installed at W7-X. In this work, we present the experimental results obtained at the high heat flux test facility GLADIS (Garching LArge DIvertor Sample test facility in IPP Garching) [1] during tests of a new plasma facing components (PFCs) protection algorithm designed for W7-X. The GLADIS device is equipped with two ion beams that can generate a heat load in the range from 3 MWm-2 to 55 MWm-2. The algorithms developed at W7-X to detect defects and hot spots are based on the analysis of surface temperature evolution and are adapted to work in near real-time. The aim of this work was to test the near real-time algorithms in conditions close to those expected in W7-X. The experiments were performed on W7-X pre-series tiles to detect CFC/Cu delaminations. For detection of surface layers, carbon fiber composite (CFC) blocks from the divertor of the Wendelstein 7-AS stellarator were used to observe temporal behavior of fully developed surface layers. These layers of re-deposited materials, like carbon, boron, oxygen and iron, were formed during the W7-AS operation. A detailed analysis of the composition and their thermal response to high heat fluxes (HHF) are described in [2]. The experiments indicate that the automatic detection of critical events works according to W7-X PFC protection requirements.

Spectroscopic imaging of limiter heat and particle fluxes and the resulting impurity sources during Wendelstein 7-X startup plasmas.

Science.gov (United States)

Stephey, L; Wurden, G A; Schmitz, O; Frerichs, H; Effenberg, F; Biedermann, C; Harris, J; König, R; Kornejew, P; Krychowiak, M; Unterberg, E A

2016-11-01

A combined IR and visible camera system [G. A. Wurden et al., "A high resolution IR/visible imaging system for the W7-X limiter," Rev. Sci. Instrum. (these proceedings)] and a filterscope system [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)] were implemented together to obtain spectroscopic data of limiter and first wall recycling and impurity sources during Wendelstein 7-X startup plasmas. Both systems together provided excellent temporal and spatial spectroscopic resolution of limiter 3. Narrowband interference filters in front of the camera yielded C-III and H α photon flux, and the filterscope system provided H α , H β , He-I, He-II, C-II, and visible bremsstrahlung data. The filterscopes made additional measurements of several points on the W7-X vacuum vessel to yield wall recycling fluxes. The resulting photon flux from both the visible camera and filterscopes can then be compared to an EMC3-EIRENE synthetic diagnostic [H. Frerichs et al., "Synthetic plasma edge diagnostics for EMC3-EIRENE, highlighted for Wendelstein 7-X," Rev. Sci. Instrum. (these proceedings)] to infer both a limiter particle flux and wall particle flux, both of which will ultimately be used to infer the complete particle balance and particle confinement time τ P .

Development of real time system imaging software for the protection of plasma facing components(PFCs) in Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Ali, Adnan; Jakubowski, Marcin; Sunn Pedersen, Thomas; Rodatos, Alexander [Max-Planck-Institute for Plasma Physics, Greifswald (Germany); Greuner, Henri [Max-Planck-Institute for Plasma Physics, Garching (Germany)

2016-07-01

One of the main aims of Wendelstein 7-X, an advanced stellarator in Greifswald, is the investigation of quasi-steady state operation of magnetic fusion devices, for which power exhaust is a very important issue. The predominant fraction of the energy lost from the confined plasma region will be removed by 10 so-called island divertors, which can sustain up to 10 MW/Sq-m. In order to protect the divertor elements from overheating and to monitor power deposition onto the divertor elements, 10 state-of-the-art infrared endoscopes will be installed at W7-X and software is under development for real-time analysis of automatic detection of the hot spots and other abnormal events. The pre-defined algorithms designed for early detection of defects e.g. hotspots, surface layers and delaminations during the discharge are being implemented into the software acquiring the images from the infrared cameras and broadcast them to the main Discharge Control System(DCS). This allows for automatic control of the scenario of the discharge in order to assure safe operation of W7-X. The first online tests of the software will soon be performed at GLADIS in Garching.

Real-time software for the fusion experiment WENDELSTEIN 7-X

International Nuclear Information System (INIS)

Laqua, Heike; Niedermeyer, Helmut; Schacht, Joerg; Spring, Anett

2006-01-01

The super conducting stellarator WENDELSTEIN 7-X will be capable of steady state operation as well as of pulsed operation. All discharge scenarios compatible with these capabilities will be supported by the control system. Each technical component and each diagnostic system will have its own control system, based on a real-time computer with the dedicated software described here, permitting autonomous operation for commissioning and testing and coordinated operation during experimental sessions. The system behaviour as far as it is relevant for the experiment, like parameters and algorithms, will be exclusively controlled by complex software objects. By changing references to these objects synchronously in all computers the whole system behaviour can be changed from one cycle to the next. All data required for the construction of the software objects will be stored in one central database and constructed in the control computers well before they are required

Spectroscopic imaging of limiter heat and particle fluxes and the resulting impurity sources during Wendelstein 7-X startup plasmas

Energy Technology Data Exchange (ETDEWEB)

Stephey, L., E-mail: stephey@wisc.edu; Schmitz, O.; Frerichs, H.; Effenberg, F. [University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States); Wurden, G. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Biedermann, C.; König, R.; Kornejew, P.; Krychowiak, M. [Max-Planck-Institut für Plasma Physik, Wendelsteinstrasse 1, 17491 Greifswald (Germany); Harris, J.; Unterberg, E. A. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2016-11-15

A combined IR and visible camera system [G. A. Wurden et al., “A high resolution IR/visible imaging system for the W7-X limiter,” Rev. Sci. Instrum. (these proceedings)] and a filterscope system [R. J. Colchin et al., Rev. Sci. Instrum. 74, 2068 (2003)] were implemented together to obtain spectroscopic data of limiter and first wall recycling and impurity sources during Wendelstein 7-X startup plasmas. Both systems together provided excellent temporal and spatial spectroscopic resolution of limiter 3. Narrowband interference filters in front of the camera yielded C-III and H{sub α} photon flux, and the filterscope system provided H{sub α}, H{sub β}, He-I, He-II, C-II, and visible bremsstrahlung data. The filterscopes made additional measurements of several points on the W7-X vacuum vessel to yield wall recycling fluxes. The resulting photon flux from both the visible camera and filterscopes can then be compared to an EMC3-EIRENE synthetic diagnostic [H. Frerichs et al., “Synthetic plasma edge diagnostics for EMC3-EIRENE, highlighted for Wendelstein 7-X,” Rev. Sci. Instrum. (these proceedings)] to infer both a limiter particle flux and wall particle flux, both of which will ultimately be used to infer the complete particle balance and particle confinement time τ{sub P}.

Bootstrap current control studies in the Wendelstein 7-X stellarator using the free-plasma-boundary version of the SIESTA MHD equilibrium code

Science.gov (United States)

Peraza-Rodriguez, H.; Reynolds-Barredo, J. M.; Sanchez, R.; Tribaldos, V.; Geiger, J.

2018-02-01

The recently developed free-plasma-boundary version of the SIESTA MHD equilibrium code (Hirshman et al 2011 Phys. Plasmas 18 062504; Peraza-Rodriguez et al 2017 Phys. Plasmas 24 082516) is used for the first time to study scenarios with considerable bootstrap currents for the Wendelstein 7-X (W7-X) stellarator. Bootstrap currents in the range of tens of kAs can lead to the formation of unwanted magnetic island chains or stochastic regions within the plasma and alter the boundary rotational transform due to the small shear in W7-X. The latter issue is of relevance since the island divertor operation of W7-X relies on a proper positioning of magnetic island chains at the plasma edge to control the particle and energy exhaust towards the divertor plates. Two scenarios are examined with the new free-plasma-boundary capabilities of SIESTA: a freely evolving bootstrap current one that illustrates the difficulties arising from the dislocation of the boundary islands, and a second one in which off-axis electron cyclotron current drive (ECCD) is applied to compensate the effects of the bootstrap current and keep the island divertor configuration intact. SIESTA finds that off-axis ECCD is indeed able to keep the location and phase of the edge magnetic island chain unchanged, but it may also lead to an undesired stochastization of parts of the confined plasma if the EC deposition radial profile becomes too narrow.

Design of Diagnostics: Case Studies for Wendelstein 7-X

International Nuclear Information System (INIS)

Dreier, H.; Dinklage, A.; Fischer, R.; Hirsch, M.; Kornejew, P.; Pasch, E.

2005-01-01

The set of start-up diagnostics for Wendelstein 7-X is oriented to resolve physical issues of stellarator optimization [1]. The diagnostics philosophy of W7-X aims at extendable set-ups which are to be supplemented along the operation of the device. Planning diagnostics directly lead to the requirement to optimize their respective outcome. In many cases, the optimization is much restricted by technical constraints. But even in those cases, figures of robustness of the chosen design settings are beneficial for the diagnostic strategy. In this paper a framework for diagnostic design is presented employing the Bayesian probability theory. Part of the approach can be regarded as a virtual diagnostic, which describes the future experimental unit including its error statistics and is able to produce artificial data. The virtual diagnostic is fed with mock-up quantities of interest and hence it enables the designer to compare the outcome of the virtual diagnostic with its input. For the design of diagnostics in fusion experiments several figures of merit are possible, depend- ing on the optimization goal. Here physical questions like estimation of the density distribution or the density gradient are possible optimization targets as well as technical issues as the robustness of density measurements, e.g, for controlling purposes. Also the estimation of derived quantities - like gradients needed for modeling of the bootstrap current or of the radial electric field - might be considered to be the goal of a diagnostic design. (Author)

Diagnostics development for steady state operation of the stellarator wendelstein 7-x

Energy Technology Data Exchange (ETDEWEB)

Burhenn, R.; Baldzuhn, J.; Dreier, H.; Endler, M.; Jimenez-Gomez, R.; Grosser, K.; Hartfuss, H.J.; Hildebrandt, D.; Hirsch, M.; Koenig, R.; Kornejew, P.; Krychowiak, M.; Laqua, H.P.; Laux, M.; Oosterbeek, J.W.; Pasch, E.; Schneider, W.; Thomsen, H.; Weller, A.; Werner, A.; Wolf, R.; Zhang, D. [Max-Planck-Institute fuer Plasmaphysik, EURATOM Association, D-17491, Greifswald (Germany); Biel, W. [Institut fuer Energieforschung - Plasmaphysik, Forschungszentrum Juelich GmbH, EURATOM Association, Trilateral Euregio Cluster, D-52425 Juelich (Germany)

2011-03-15

The gain in experience with long-pulse operation under fusion relevant plasma conditions is an important step towards successful sustainment of future steady state reactor plasmas. The stellarator Wendelstein 7-X (W7-X) [1], presently being under construction, is already equipped with a superconducting coil system and principally capable of quasi-continuous operation. Like other long pulse devices, W7-X is faced with new enhanced technical requirements which have to be met by plasma facing components as well as the diagnostic systems in general. Water-cooled windows were qualified up to 60 kW/m{sup 2} thermal load, and shutters against evaporation of sensitive elements outside the attended time of the diagnostic as well as for baseline control had been developed. Shielding of in-vessel components against damage by absorption of microwave stray radiation originating from the heating systems appears to be one of the most challenging tasks. Experiments using a microwave test chamber identify critical materials and approved the necessity for careful shielding of both, sensitive diagnostics and cables. Spectroscopic systems for monitoring the impurity content and divertor load as well as for robust density measurement are presented (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Contribution IFJ PAN to the construction of the Wendelstein 7-X stellarator (2008 - 2009)

International Nuclear Information System (INIS)

Blocki, J.; Hajduk, L.; Kotula, J.; Stodulski, M.; Sulek, Z.

2010-05-01

The Wendelstein 7-X stellarator is now being assembled at the Max Planck Institute for Plasma Physic (IPP), Greifswald, Germany. The Agreement on Cooperation between the Max-Planck-Institut fur Plasmaphysik in Garching and the Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences in Krakow (IFJ PAN) was signed off in 2007. The intention of the agreement is to cover the whole period of the W7-X construction. According to the agreement IFJ PAN has taken over the following tasks: 1. to assembly of the bus bar system powering the superconducting coils of the stellarator; 2. to take part in design of equipment used during handling, transportation and assembly of outer vessels; 3. to manufacture 30 polichromators used for plasma diagnostics. Task No 2 was completed in 2008 while tasks No 1 and 3 are to be continued. (authors)

Advanced electron cyclotron heating and current drive experiments on the stellarator Wendelstein 7-X

Directory of Open Access Journals (Sweden)

Stange Torsten

2017-01-01

Full Text Available During the first operational phase (OP 1.1 of Wendelstein 7-X (W7-X electron cyclotron resonance heating (ECRH was the exclusive heating method and provided plasma start-up, wall conditioning, heating and current drive. Six gyrotrons were commissioned for OP1.1 and used in parallel for plasma operation with a power of up to 4.3 MW. During standard X2-heating the spatially localized power deposition with high power density allowed controlling the radial profiles of the electron temperature and the rotational transform. Even though W7-X was not fully equipped with first wall tiles and operated with a graphite limiter instead of a divertor, electron densities of n e > 3·1019 m-3 could be achieved at electron temperatures of several keV and ion temperatures above 2 keV. These plasma parameters allowed the first demonstration of a multipath O2-heating scenario, which is envisaged for safe operation near the X-cutoff-density of 1.2·1020 m-3 after full commissioning of the ECRH system in the next operation phase OP1.2.

Core radial electric field and transport in Wendelstein 7-X plasmas

Science.gov (United States)

Pablant, N. A.; Langenberg, A.; Alonso, A.; Beidler, C. D.; Bitter, M.; Bozhenkov, S.; Burhenn, R.; Beurskens, M.; Delgado-Aparicio, L.; Dinklage, A.; Fuchert, G.; Gates, D.; Geiger, J.; Hill, K. W.; Höfel, U.; Hirsch, M.; Knauer, J.; Krämer-Flecken, A.; Landreman, M.; Lazerson, S.; Maaßberg, H.; Marchuk, O.; Massidda, S.; Neilson, G. H.; Pasch, E.; Satake, S.; Svennson, J.; Traverso, P.; Turkin, Y.; Valson, P.; Velasco, J. L.; Weir, G.; Windisch, T.; Wolf, R. C.; Yokoyama, M.; Zhang, D.; W7-X Team

2018-02-01

The results from the investigation of neoclassical core transport and the role of the radial electric field profile (Er) in the first operational phase of the Wendelstein 7-X (W7-X) stellarator are presented. In stellarator plasmas, the details of the Er profile are expected to have a strong effect on both the particle and heat fluxes. Investigation of the radial electric field is important in understanding neoclassical transport and in validation of neoclassical calculations. The radial electric field is closely related to the perpendicular plasma flow (u⊥) through the force balance equation. This allows the radial electric field to be inferred from measurements of the perpendicular flow velocity, which can be measured using the x-ray imaging crystal spectrometer and correlation reflectometry diagnostics. Large changes in the perpendicular rotation, on the order of Δu⊥˜ 5 km/s (ΔEr ˜ 12 kV/m), have been observed within a set of experiments where the heating power was stepped down from 2 MW to 0.6 MW. These experiments are examined in detail to explore the relationship between heating power temperature, and density profiles and the radial electric field. Finally, the inferred Er profiles are compared to initial neoclassical calculations based on measured plasma profiles. The results from several neoclassical codes, sfincs, fortec-3d, and dkes, are compared both with each other and the measurements. These comparisons show good agreement, giving confidence in the applicability of the neoclassical calculations to the W7-X configuration.

W7-AS: One step of the Wendelstein stellarator linea)

Science.gov (United States)

Wagner, F.; Bäumel, S.; Baldzuhn, J.; Basse, N.; Brakel, R.; Burhenn, R.; Dinklage, A.; Dorst, D.; Ehmler, H.; Endler, M.; Erckmann, V.; Feng, Y.; Gadelmeier, F.; Geiger, J.; Giannone, L.; Grigull, P.; Hartfuss, H.-J.; Hartmann, D.; Hildebrandt, D.; Hirsch, M.; Holzhauer, E.; Igitkhanov, Y.; Jänicke, R.; Kick, M.; Kislyakov, A.; Kisslinger, J.; Klinger, T.; Klose, S.; Knauer, J. P.; König, R.; Kühner, G.; Laqua, H. P.; Maassberg, H.; McCormick, K.; Niedermeyer, H.; Nührenberg, C.; Pasch, E.; Ramasubramanian, N.; Ruhs, N.; Rust, N.; Sallander, E.; Sardei, F.; Schubert, M.; Speth, E.; Thomsen, H.; Volpe, F.; Weller, A.; Werner, A.; Wobig, H.; Würsching, E.; Zarnstorff, M.; Zoletnik, S.

2005-07-01

This paper is a summary of some of the major results from the Wendelstein 7-AS stellarator (W7-AS). W7-AS [G. Grieger et al., Phys. Fluids B 4, 2081 (1992)] has demonstrated the feasibility of modular coils and has pioneered the island divertor and the modeling of its three-dimensional characteristics with the EMC3/EIRENE code [Y. Feng, F. Sardei et al., Plasma Phys. Controlled Fusion 44, 611 (2002)]. It has extended the operational range to high density (4×1020m-3 at 2.5T) and high ⟨β⟩ (3.4% at 0.9T); it has demonstrated successfully the application of electron cyclotron resonance heating (ECRH) beyond cutoff via electron Bernstein wave heating, and it has utilized the toroidal variation of the magnetic field strength for ion cyclotron resonance frequency beach-wave heating. In preparation of W7-X [J. Nührenberg et al., Trans. Fusion Technol. 27, 71 (1995)], aspects of the optimization concept of the magnetic design have been successfully tested. W7-AS has accessed the H-mode, the first time in a "non-tokamak" and has extended H-mode operation toward high density by the discovery of the high-density H-mode (HDH), characterized by H-mode energy and L-mode-level impurity confinement. In the HDH-mode quasisteady state operation is possible close to operational limits without noticeable degradation in the plasma properties. High-β phases up to tpulse/τE=65 have been achieved, which can already be taken as an indication of the intrinsic stellarator capability of steady-state operation. Confinement issues will be discussed with emphasis on the similarities to tokamak confinement (general transport properties, H-mode transition physics) but also with respect to distinct differences (no confinement degradation toward operational boundaries, positive density scaling, lack of profile resilience, no distinct isotope effect, H-mode operational window). W7-AS turned out to be an important step in the development of the Wendelstein stellarator line towards an

The long way to steady state fusion plasmas - the superconducting stellarator device Wendelstein 7-X

CERN Multimedia

CERN. Geneva

2016-01-01

The stable generation of high temperature Hydrogen plasmas (ion and electron temperature in the range 10-20 keV) is the basis for the use of nuclear fusion to generate heat and thereby electric power. The most promising path is to use strong, toroidal, twisted magnetic fields to confine the electrically charged plasma particles in order to avoid heat losses to the cold, solid wall elements. Two magnetic confinement concepts have been proven to be most suitable: (a) the tokamak and (b) the stellarator. The stellarator creates the magnetic field by external coils only, the tokamak by combining the externally created field with the magnetic field generated by a strong current in the plasma. “Wendelstein 7-X” is the name of a large superconducting stellarator that went successfully into operation after 15 years of construction. With 30 m3 plasma volume, 3 T magnetic field on axis, and 10 MW micro wave heating power, Hydrogen plasmas are generated that allow one to establish a scientific basis for the extrapol...

Status of construction and assembly of Wendelstein 7-X

International Nuclear Information System (INIS)

Hartmann, D.A.

2005-01-01

Wendelstein 7-X (W7-X) is a low-shear stellarator with an optimized quasi-isodynamic configuration and five-fold symmetry that is presently under construction in Greifswald, Germany. The goal of the device is to investigate the fusion reactor capability of stellarators. Therefore the magnetic field will be generated using superconducting coils and all relevant components (10 MW ECR heating system, divertor and wall protection elements) are designed for 30 min. operation, which is equivalent to steady-state. The basic parameters of the device are: magnetic field up to 3 T on axis, major radius 5.5 m, average minor radius 0.55m. The device consists of 50 non-planar and 20 planar coils, the coil support structure, 10 plasma vessel half modules, 10 outer vessel half shells and 299 ports. Presently of the non- planar coils 38 winding packs have been produced, of which 25 have been embedded. Two of the coils have been successfully tested for their cryogenic and superconducting properties at the test site at CEA Saclay and were delivered. Of the planar coils all 20 winding packs have been produced, 5 have been embedded. 6 of the plasma vessel half modules and about 180 of the ports have been delivered. The first module of the coil support structure is being machined and will be delivered in fall 2005. The assembly of the device started last fall: diagnostic Mirnov coils were attached to the outside of the plasma vessel, sections of the super-insulation were added, the first coil was threaded onto a section of a plasma vessel half module and a second section was welded onto the first catching the threaded coil in between. Presently the further progress of assembly is slowed down by the required reworking of several coils. The inside of the plasma vessel will be fully lined by water cooled structures: divertor modules consisting of CFC elements brazed onto CuCrZr substructures for areas with convective losses up to 10 MW/m 2 and double-walled stainless steel panels for

High heat flux tests of the WENDELSTEIN 7-X pre-series target elements

International Nuclear Information System (INIS)

Greuner, H.; Boeswirth, B.; Boscary, J.; Plankensteiner, A.; Schedler, B.

2007-01-01

The high heat flux (HHF) testing of WENDELSTEIN 7-X pre-series target elements is an indispensable step in the qualification of the manufacturing process. A set of 20 full scale pre-series elements was manufactured by PLANSEE SE to validate the materials and manufacturing technologies prior to the start of the series production. The HHF tests were performed in the ion beam test facility GLADIS. All actively water-cooled elements were tested for about 100 cycles at 10 MW/m 2 (10-15 s pulse duration). Several elements were loaded with even higher cycle numbers (up to 1000) and heat loads up to 24 MW/m 2 . Hot spots were, observed at the edges of several tiles during the HHF tests indicating local bonding problems of the CFC. The thermo-mechanical behaviour under HHF loading has been evaluated and compared to the FEM predictions. The measured temperatures and strains confirm the chosen FEM approach. This allows a component optimisation to achieve a successful series production of the W7-X divertor target elements

Control of the magnetic topology and plasma exhaust in the edge region of Wendelstein 7-X. A numerical study

Energy Technology Data Exchange (ETDEWEB)

Hoelbe, Hauke

2016-02-15

Nuclear fusion is the energy source of the stars and has the potential of being the main energy source for mankind in the future. The research on fusion energy focuses primarily on magnetic confinement, where hot plasma - with temperatures on the order of 100 million degrees Celsius - are confined by specially designed toroidal magnetic topology. The main candidates for magnetic confinement are the tokamak and the stellarator. The tokamak concept is further developed than the stellarator concept, but the stellarator concept has some intrinsic and potentially very important advantages and is therefore also actively pursued. The Wendelstein 7-X (W7-X) stellarator will be the world's leading stellarator experiment. It is about to go into operation in Greifswald, Germany. This thesis delves into some very important scientific challenges for the stellarator concept as a whole and W7-X in particular, namely, how one effectively interfaces the hot plasma with the material walls of the experiment, in special how the plasma heat and particle fluxes are controlled. The fundamental concept that will be used in W7-X for particle and heat exhaust is the island divertor. Although the divertor concept at a stellarator was invented by Lyman Spitzer back in the 1950s, the stellarator island divertor still needs to be experimentally tested at fusion-relevant heat loads and temperatures in steady-state. W7-X is the first experiment that will be able to do so. A number of theoretical and numerical studies have been performed to guide the design of the divertor components. The actual divertor components are in series production at this time, and are largely compatible with the expected heat loads. However, with the sophisticated codes now available, it has become clear that there are some, otherwise very attractive, operational scenarios that could lead to overloading of the W7-X divertors. At least one mitigation strategy was proposed but was until now not analyzed in sufficient

Control of the magnetic topology and plasma exhaust in the edge region of Wendelstein 7-X. A numerical study

International Nuclear Information System (INIS)

Hoelbe, Hauke

2016-01-01

Nuclear fusion is the energy source of the stars and has the potential of being the main energy source for mankind in the future. The research on fusion energy focuses primarily on magnetic confinement, where hot plasma - with temperatures on the order of 100 million degrees Celsius - are confined by specially designed toroidal magnetic topology. The main candidates for magnetic confinement are the tokamak and the stellarator. The tokamak concept is further developed than the stellarator concept, but the stellarator concept has some intrinsic and potentially very important advantages and is therefore also actively pursued. The Wendelstein 7-X (W7-X) stellarator will be the world's leading stellarator experiment. It is about to go into operation in Greifswald, Germany. This thesis delves into some very important scientific challenges for the stellarator concept as a whole and W7-X in particular, namely, how one effectively interfaces the hot plasma with the material walls of the experiment, in special how the plasma heat and particle fluxes are controlled. The fundamental concept that will be used in W7-X for particle and heat exhaust is the island divertor. Although the divertor concept at a stellarator was invented by Lyman Spitzer back in the 1950s, the stellarator island divertor still needs to be experimentally tested at fusion-relevant heat loads and temperatures in steady-state. W7-X is the first experiment that will be able to do so. A number of theoretical and numerical studies have been performed to guide the design of the divertor components. The actual divertor components are in series production at this time, and are largely compatible with the expected heat loads. However, with the sophisticated codes now available, it has become clear that there are some, otherwise very attractive, operational scenarios that could lead to overloading of the W7-X divertors. At least one mitigation strategy was proposed but was until now not analyzed in sufficient

Laboratory tests of the Pulse Height Analysis system for Wendelstein 7-X

Science.gov (United States)

Kubkowska, M.; Czarnecka, A.; Figacz, W.; Jabłoński, S.; Kaczmarczyk, J.; Krawczyk, N.; Ryć, L.; Biedermann, C.; Koenig, R.; Thomsen, H.; Weller, A.; W7-X Team

2015-10-01

A pulse height analysis (PHA) system has been designed and manufactured for the Wendelstein 7-X stellarator, in such a way as to be already compatible with later quasi-continuous operation requirements. The diagnostic will provide X-ray spectra with energy resolution better than 180 eV . The system has three energy channels: 0.25-20 keV, 0.95-20 keV and 1.5-20 keV . For each channel a separate Silicon Drift Detector (SDD) equipped with a suitably selected beryllium foil is used. The range of the 3 energy channels can be further adapted to particular experiments by moving via a pneumatic actuator additional beryllium filters in front of the fixed ones. The PHA system is intended for measuring impurity species (e.g. C, Fe, Ni), electron temperature and for investigating possible suprathermal tails in the spectra. The system will be installed on the horizontal port AEK50 on W7-X. The SDD detectors, the replaceable filters and the adjustable piezo driven slits which allow to suitably adapt the X-ray signal intensity are mounted inside a vacuum chamber which is connected to the plasma vessel via a gate valve. The on-air diagnostic components are the preamplifiers, the Digital X-Ray Processor (XIA, U.S.A.), a computer, and an X-ray calibration source. For controlling the operation of the entire diagnostic system, as well as, for the data acquisition of the electrical pulses coming a special code was developed. The paper presents the construction of the PHA system for W7-X and the laboratory tests of its mechanical parts together with the information on the code developed to operate the diagnostic. The diagnostic was also tested and characterised by measuring Fe55 spectrum and fluorescence spectra of Ni, Fe, Cr and Cu induced by an X-ray mini-tube.

Design of a remote steering antenna for ECRH heating in the stellarator Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Plaum, B., E-mail: plaum@igvp.uni-stuttgart.de [Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie (IGVP), Univ. Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Lechte, C.; Kasparek, W.; Gaiser, S.; Zeitler, A. [Institut für Grenzflächenverfahrenstechnik und Plasmatechnologie (IGVP), Univ. Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Erckmann, V. [Max-Planck-Institut für Plasmaphysik, EURATOM-IPP, D-17491 Greifswald (Germany); Weißgerber, M. [Max-Planck-Institut für Plasmaphysik, EURATOM-IPP, D-85748 Garching (Germany); Bechtold, A. [NTG Neue Technologie GmbH & Co KG, D-63571 Gelnhausen (Germany); Busch, M.; Szcepaniak, B. [Galvano-T electroplating-electroforming GmbH, D-51570 Windeck-Rosbach (Germany)

2015-10-15

Highlights: • We report about the design activities for the remote steering antennas for the stellarator W7-X. • The integration into the W7-X system and the manufacturing procedure are described. • Simulations and loss measurements for the waveguide walls were done and are in good agreement. • A method for extending the steering range is presented. • A mechanical deformation analysis showed that the deformation is not critical for the beam quality. - Abstract: For the ECRH heating system of the stellarator Wendelstein 7-X, two remote steering antennas are developed and manufactured. The principle of remote steering antennas is based on the imaging characteristics of corrugated rectangular waveguides, which is well understood and can accurately be simulated. Several details, however, require deeper investigation. The antenna needs a miter-bend and a 24 mm gap. The positions of these elements need to be chosen carefully to reduce losses and stray radiation. The antennas are manufactured from copper by electroforming. This allows to integrate all components, including the corrugated inner walls and the cooling channels, in one vacuum-tight piece. This paper reviews the design process of the remote steering antennas for W7-X as well as technological issues and experimental results from test pieces.

Analysis of Consequences in the Loss-of-Coolant Accident in Wendelstein 7-X Experimental Nuclear Fusion Facility

Energy Technology Data Exchange (ETDEWEB)

Uspuras, E., E-mail: algis@mail.lei.lt [Laboratory of Nuclear Installations Safety, Lithuanian Energy Institute, Kaunas (Lithuania)

2012-09-15

Full text: Fusion is the energy production technology, which could potentially solve problems with growing energy demand of population in the future. Starting 2007, Lithuanian energy institute (LEI) is a member of European Fusion Development Agreement (EFDA) organization. LEI is cooperating with Max Planck Institute for Plasma Physics (IPP, Germany) in the frames of EFDA project by performing safety analysis of fusion device W7-X. Wendelstein 7-X (W7-X) is an experimental stellarator facility currently being built in Greifswald, Germany, which shall demonstrate that in the future energy could be produced in such type of fusion reactors. The W7-X facility divertor cooling system consists of two coolant circuits: the main cooling circuit and the so-called 'baking' circuit. Before plasma operation, the divertor and other invessel components must be heated up in order to 'clean' the surfaces by thermal desorption and the subsequent pumping out of the released volatile molecules. The rupture of pipe, providing water for the divertor targets during the 'baking' regime is one of the critical failure events, since primary and secondary steam production leads to a rapid increase of the inner pressure in the plasma (vacuum) vessel. Such initiating event could lead to the loss of vacuum condition up to overpressure of the plasma vessel, damage of in-vessel components and bellows of the ports. In this paper the safety analysis of 40 mm inner diameter coolant pipe rupture in cooling circuit and discharge of steam-water mixture through the leak into plasma vessel during the W7-X no-plasma 'baking' operation mode is presented. For the analysis the model of W7-X cooling system (pumps, valves, pipes, hydro-accumulators, and heat exchangers) and plasma vessel was developed by employing system thermal-hydraulic state-of-the-art RELAP5 Mod 3.3 code. This paper demonstrated, that the developed RELAP5 model allows to analyze the processes in divertor cooling system and plasma vessel

Calibration and use cases of the electron cyclotron emission diagnostic at Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Hoefel, Udo; Hirsch, Matthias; Ewert, Karsten; Hartfuss, Hans-Juergen; Laqua, Heinrich Peter; Stange, Torsten; Wolf, Robert [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Collaboration: the W7-X Team

2016-07-01

The world's largest stellarator, Wendelstein 7-X (W7-X), is equipped with a 140 GHz electron cyclotron resonance heating (ECRH) system providing up to 5 MW absorbed power in the first operation phase OP1.1. The foreseen X2-heating scenario uses the high absorption of the second harmonic extraordinary electron cyclotron waves, which leads on the other hand to a black body electron cyclotron emission (ECE) being proportional to the local electron temperature. ECE is one of the fundamental operating diagnostics and is planned to yield the electron temperature profile from the very first discharges onwards. Unlike most other ECE diagnostics, the 32 channel ECE radiometer diagnostic (with additional 16 channels with higher radial resolution) at W7-X is absolutely calibrated. It is planned to use this diagnostic for intensive studies on electron heat transport in the upcoming operational phases of W7-X. Simple switch-off experiments for the determination of the energy confinement time should already be possible within the first plasma shots. Due to the high temporal and radial resolution the ECE will be used also to determine the power deposition by modulation of the heating gyrotron. or the localization of a power modulated ECRH to optimize the power deposition. If reasonably equilibrated plasma conditions could be generated in the first operational phase (OP 1.1), first studies on electron thermal diffusivity could also be possible.

Diagnostic developments for quasicontinuous operation of the Wendelstein 7-X stellarator

International Nuclear Information System (INIS)

Koenig, R.; Cantarini, J.; Dreier, H.; Erckmann, V.; Hildebrandt, D.; Hirsch, M.; Kornejew, P.; Laux, M.; Laqua, H.; Pasch, E.; Thomsen, H.; Weller, A.; Werner, A.; Wolf, R.; Ye, M. Y.; Kocsis, G.; Recsei, S.; Zoletnik, S.; Szabo, V.

2008-01-01

The stellarator Wendelstein 7-X will allow for quasicontinuous operation with the duration only being limited to two 30 min discharges per day, at a continuous heating power of 10 MW electron cyclotron resonance heating (ECRH) at 140 GHz, by the capacity of the cooling water reservoir. This will result in high thermal loads on all plasma facing components of 50-100 kW/m 2 from radiation alone and of up to about 500 kW/m 2 on components additionally exposed to convective loads. In high density scenarios toroidally varying ECRH stray radiation levels of 50-200 kW/m 2 need to be coped with, requiring careful material selection and different shielding and hardening techniques. Furthermore, a gradual buildup of coatings on plasma facing optical components, which without any measures being taken, would lead to high transmission losses already within a few days of long pulse operation (equivalent to about 1 year of operation in pulsed devices like JET or ASDEX-upgrade) and therefore needs to be prevented as much as possible. In addition in situ cleaning as well as absolute calibration techniques need to be developed for all plasma facing optical systems. Here we report about some of our efforts to find, for various types of diagnostics, ways to cope with these adverse effects. Moreover, we give a few examples for individual diagnostic specific issues with respect to quasicontinuous operation, such as the development of a special integrator for the magnetic diagnostics as well as special interferometer types which can cope with unavoidable vibrations and slow path length changes due to, e.g., thermal expansion of the plasma vessel.

Wendelstein 7-X Torus Hall Layout and System Integration

International Nuclear Information System (INIS)

Hartmann, D.; Damiani, C.; Hartfuss, H.-J.; Krampitz, R.; Neuner, U.

2006-01-01

Wendelstein 7-X is an experimental fusion device presently under construction in Greifswald, Germany, to study the stellarator concept at reactor relevant parameters und steady-state conditions. The heart of the machine consists of the torus that houses the superconducting coils and the plasma vacuum vessel. It is located nearly in the center of a 30 m x 30 m x 20 m hall. A large number of components need to be placed in close proximity of the torus to provide the system with the required means, e.g. cryogenic gases, cooling water, electricity, and to integrate it with the peripheral diagnostic and heating components. The arrangement of these components has to be supported by suitable structures, and has to be optimized to allow for installation, maintenance, and repair. In addition, space has to be provided for escape routes and for sufficient distance between components that could negatively influence each other's performance, etc. The layout of the components has been done over many years using 3D CAD software. It was based on simple geometric models of the components and of the additionally required space. Presently the layout design is being detailed and updated by replacing the original coarse models with more refined estimates or - in some cases - with as-built models. All interface requirements are carefully taken into account. Detailed routing was specified for the cryo and cooling water supply lines whose design and installation is outsourced. Due to the limited space available and severely restricted access during experimental campaigns, the requirement to put auxiliary components like electronic racks into the torus hall is being queried. The paper summarizes the present state of the component layout in the torus hall, and how the peripheral supply, diagnostics, and heating systems are integrated into the machine. (author)

First steps towards modeling of ion-driven turbulence in Wendelstein 7-X

Science.gov (United States)

Warmer, F.; Xanthopoulos, P.; Proll, J. H. E.; Beidler, C. D.; Turkin, Y.; Wolf, R. C.

2018-01-01

Due to foreseen improvement of neoclassical confinement in optimised stellarators—like the newly commissioned Wendelstein 7-X (W7-X) experiment in Greifswald, Germany—it is expected that turbulence will significantly contribute to the heat and particle transport, thus posing a limit to the performance of such devices. In order to develop discharge scenarios, it is thus necessary to develop a model which could reliably capture the basic characteristics of turbulence and try to predict the levels thereof. The outcome will not only be affordable, using only a fraction of the computational cost which is normally required for repetitive direct turbulence simulations, but would also highlight important physics. In this model, we seek to describe the ion heat flux caused by ion temperature gradient (ITG) micro-turbulence, which, in certain heating scenarios, can be a strong source of free energy. With the aid of a relatively small number of state-of-the-art nonlinear gyrokinetic simulations, an initial critical gradient model (CGM) is devised, with the aim to replace an empirical model, stemming from observations in prior stellarator experiments. The novel CGM, in its present form, encapsulates all available knowledge about ion-driven 3D turbulence to date, also allowing for further important extensions, towards an accurate interpretation and prediction of the ‘anomalous’ transport. The CGM depends on the stiffness of the ITG turbulence scaling in W7-X, and implicitly includes the nonlinear zonal flow response. It is shown that the CGM is suitable for a 1D framework turbulence modeling.

Major results from the first plasma campaign of the Wendelstein 7-X stellarator

Science.gov (United States)

Wolf, R. C.; Ali, A.; Alonso, A.; Baldzuhn, J.; Beidler, C.; Beurskens, M.; Biedermann, C.; Bosch, H.-S.; Bozhenkov, S.; Brakel, R.; Dinklage, A.; Feng, Y.; Fuchert, G.; Geiger, J.; Grulke, O.; Helander, P.; Hirsch, M.; Höfel, U.; Jakubowski, M.; Knauer, J.; Kocsis, G.; König, R.; Kornejew, P.; Krämer-Flecken, A.; Krychowiak, M.; Landreman, M.; Langenberg, A.; Laqua, H. P.; Lazerson, S.; Maaßberg, H.; Marsen, S.; Marushchenko, M.; Moseev, D.; Niemann, H.; Pablant, N.; Pasch, E.; Rahbarnia, K.; Schlisio, G.; Stange, T.; Pedersen, T. Sunn; Svensson, J.; Szepesi, T.; Trimino Mora, H.; Turkin, Y.; Wauters, T.; Weir, G.; Wenzel, U.; Windisch, T.; Wurden, G.; Zhang, D.; Abramovic, I.; Äkäslompolo, S.; Aleynikov, P.; Aleynikova, K.; Alzbutas, R.; Anda, G.; Andreeva, T.; Ascasibar, E.; Assmann, J.; Baek, S.-G.; Banduch, M.; Barbui, T.; Barlak, M.; Baumann, K.; Behr, W.; Benndorf, A.; Bertuch, O.; Biel, W.; Birus, D.; Blackwell, B.; Blanco, E.; Blatzheim, M.; Bluhm, T.; Böckenhoff, D.; Bolgert, P.; Borchardt, M.; Borsuk, V.; Boscary, J.; Böttger, L.-G.; Brand, H.; Brandt, Ch.; Bräuer, T.; Braune, H.; Brezinsek, S.; Brunner, K.-J.; Brünner, B.; Burhenn, R.; Buttenschön, B.; Bykov, V.; Calvo, I.; Cannas, B.; Cappa, A.; Carls, A.; Carraro, L.; Carvalho, B.; Castejon, F.; Charl, A.; Chernyshev, F.; Cianciosa, M.; Citarella, R.; Ciupiński, Ł.; Claps, G.; Cole, M.; Cole, M. J.; Cordella, F.; Cseh, G.; Czarnecka, A.; Czermak, A.; Czerski, K.; Czerwinski, M.; Czymek, G.; da Molin, A.; da Silva, A.; Dammertz, G.; Danielson, J.; de la Pena, A.; Degenkolbe, S.; Denner, P.; Dhard, D. P.; Dostal, M.; Drevlak, M.; Drewelow, P.; Drews, Ph.; Dudek, A.; Dundulis, G.; Durodie, F.; van Eeten, P.; Effenberg, F.; Ehrke, G.; Endler, M.; Ennis, D.; Erckmann, E.; Esteban, H.; Estrada, T.; Fahrenkamp, N.; Feist, J.-H.; Fellinger, J.; Fernandes, H.; Fietz, W. H.; Figacz, W.; Fontdecaba, J.; Ford, O.; Fornal, T.; Frerichs, H.; Freund, A.; Führer, M.; Funaba, T.; Galkowski, A.; Gantenbein, G.; Gao, Y.; García Regaña, J.; Garcia-Munoz, M.; Gates, D.; Gawlik, G.; Geiger, B.; Giannella, V.; Gierse, N.; Gogoleva, A.; Goncalves, B.; Goriaev, A.; Gradic, D.; Grahl, M.; Green, J.; Grosman, A.; Grote, H.; Gruca, M.; Guerard, C.; Haiduk, L.; Han, X.; Harberts, F.; Harris, J. H.; Hartfuß, H.-J.; Hartmann, D.; Hathiramani, D.; Hein, B.; Heinemann, B.; Heitzenroeder, P.; Henneberg, S.; Hennig, C.; Hernandez Sanchez, J.; Hidalgo, C.; Hölbe, H.; Hollfeld, K. P.; Hölting, A.; Höschen, D.; Houry, M.; Howard, J.; Huang, X.; Huber, M.; Huber, V.; Hunger, H.; Ida, K.; Ilkei, T.; Illy, S.; Israeli, B.; Ivanov, A.; Jablonski, S.; Jagielski, J.; Jelonnek, J.; Jenzsch, H.; Junghans, P.; Kacmarczyk, J.; Kaliatka, T.; Kallmeyer, J.-P.; Kamionka, U.; Karalevicius, R.; Kasahara, H.; Kasparek, W.; Kenmochi, N.; Keunecke, M.; Khilchenko, A.; Kinna, D.; Kleiber, R.; Klinger, T.; Knaup, M.; Kobarg, Th.; Köchl, F.; Kolesnichenko, Y.; Könies, A.; Köppen, M.; Koshurinov, J.; Koslowski, R.; Köster, F.; Koziol, R.; Krämer, M.; Krampitz, R.; Kraszewsk, P.; Krawczyk, N.; Kremeyer, T.; Krings, Th.; Krom, J.; Krzesinski, G.; Ksiazek, I.; Kubkowska, M.; Kühner, G.; Kurki-Suonio, T.; Kwak, S.; Lang, R.; Langish, S.; Laqua, H.; Laube, R.; Lechte, C.; Lennartz, M.; Leonhardt, W.; Lewerentz, L.; Liang, Y.; Linsmeier, Ch.; Liu, S.; Lobsien, J.-F.; Loesser, D.; Loizu Cisquella, J.; Lore, J.; Lorenz, A.; Losert, M.; Lubyako, L.; Lücke, A.; Lumsdaine, A.; Lutsenko, V.; Majano-Brown, J.; Marchuk, O.; Mardenfeld, M.; Marek, P.; Massidda, S.; Masuzaki, S.; Maurer, D.; McCarthy, K.; McNeely, P.; Meier, A.; Mellein, D.; Mendelevitch, B.; Mertens, Ph.; Mikkelsen, D.; Mishchenko, O.; Missal, B.; Mittelstaedt, J.; Mizuuchi, T.; Mollen, A.; Moncada, V.; Mönnich, T.; Morizaki, T.; Munk, R.; Murakami, S.; Musielok, F.; Náfrádi, G.; Nagel, M.; Naujoks, D.; Neilson, H.; Neubauer, O.; Neuner, U.; Ngo, T.; Nocentini, R.; Nührenberg, C.; Nührenberg, J.; Obermayer, S.; Offermanns, G.; Ogawa, K.; Ongena, J.; Oosterbeek, J. W.; Orozco, G.; Otte, M.; Pacios Rodriguez, L.; Pan, W.; Panadero, N.; Panadero Alvarez, N.; Panin, A.; Papenfuß, D.; Paqay, S.; Pavone, A.; Pawelec, E.; Pelka, G.; Peng, X.; Perseo, V.; Peterson, B.; Pieper, A.; Pilopp, D.; Pingel, S.; Pisano, F.; Plaum, B.; Plunk, G.; Povilaitis, M.; Preinhaelter, J.; Proll, J.; Puiatti, M.-E.; Sitjes, A. Puig; Purps, F.; Rack, M.; Récsei, S.; Reiman, A.; Reiter, D.; Remppel, F.; Renard, S.; Riedl, R.; Riemann, J.; Rimkevicius, S.; Riße, K.; Rodatos, A.; Röhlinger, H.; Romé, M.; Rong, P.; Roscher, H.-J.; Roth, B.; Rudischhauser, L.; Rummel, K.; Rummel, T.; Runov, A.; Rust, N.; Ryc, L.; Ryosuke, S.; Sakamoto, R.; Samartsev, A.; Sanchez, M.; Sano, F.; Satake, S.; Satheeswaran, G.; Schacht, J.; Schauer, F.; Scherer, T.; Schlaich, A.; Schlüter, K.-H.; Schmitt, J.; Schmitz, H.; Schmitz, O.; Schmuck, S.; Schneider, M.; Schneider, W.; Scholz, M.; Scholz, P.; Schrittwieser, R.; Schröder, M.; Schröder, T.; Schroeder, R.; Schumacher, H.; Schweer, B.; Shanahan, B.; Shikhovtsev, I. V.; Sibilia, M.; Sinha, P.; Sipliä, S.; Skodzik, J.; Slaby, C.; Smith, H.; Spiess, W.; Spong, D. A.; Spring, A.; Stadler, R.; Standley, B.; Stephey, L.; Stoneking, M.; Stridde, U.; Sulek, Z.; Surko, C.; Suzuki, Y.; Szabó, V.; Szabolics, T.; Szökefalvi-Nagy, Z.; Tamura, N.; Terra, A.; Terry, J.; Thomas, J.; Thomsen, H.; Thumm, M.; von Thun, C. P.; Timmermann, D.; Titus, P.; Toi, K.; Travere, J. M.; Traverso, P.; Tretter, J.; Tsuchiya, H.; Tsujimura, T.; Tulipán, S.; Turnyanskiy, M.; Unterberg, B.; Urban, J.; Urbonavicius, E.; Vakulchyk, I.; Valet, S.; van Millingen, B.; Vela, L.; Velasco, J.-L.; Vergote, M.; Vervier, M.; Vianello, N.; Viebke, H.; Vilbrandt, R.; Vorkörper, A.; Wadle, S.; Wagner, F.; Wang, E.; Wang, N.; Warmer, F.; Wegener, L.; Weggen, J.; Wei, Y.; Wendorf, J.; Werner, A.; Wiegel, B.; Wilde, F.; Winkler, E.; Winters, V.; Wolf, S.; Wolowski, J.; Wright, A.; Xanthopoulos, P.; Yamada, H.; Yamada, I.; Yasuhara, R.; Yokoyama, M.; Zajac, J.; Zarnstorff, M.; Zeitler, A.; Zhang, H.; Zhu, J.; Zilker, M.; Zimbal, A.; Zocco, A.; Zoletnik, S.; Zuin, M.

2017-10-01

After completing the main construction phase of Wendelstein 7-X (W7-X) and successfully commissioning the device, first plasma operation started at the end of 2015. Integral commissioning of plasma start-up and operation using electron cyclotron resonance heating (ECRH) and an extensive set of plasma diagnostics have been completed, allowing initial physics studies during the first operational campaign. Both in helium and hydrogen, plasma breakdown was easily achieved. Gaining experience with plasma vessel conditioning, discharge lengths could be extended gradually. Eventually, discharges lasted up to 6 s, reaching an injected energy of 4 MJ, which is twice the limit originally agreed for the limiter configuration employed during the first operational campaign. At power levels of 4 MW central electron densities reached 3  ×  1019 m-3, central electron temperatures reached values of 7 keV and ion temperatures reached just above 2 keV. Important physics studies during this first operational phase include a first assessment of power balance and energy confinement, ECRH power deposition experiments, 2nd harmonic O-mode ECRH using multi-pass absorption, and current drive experiments using electron cyclotron current drive. As in many plasma discharges the electron temperature exceeds the ion temperature significantly, these plasmas are governed by core electron root confinement showing a strong positive electric field in the plasma centre.

Processing of the quench detection signals in W7-X

International Nuclear Information System (INIS)

Birus, Dietrich; Schneider, Matthias; Rummel, Thomas; Fricke, Marko; Petry, Klaus; Ebersoldt, Andreas

2009-01-01

The Wendelstein 7-X (W7-X) project uses superconductive coils for generation of the magnetic field to keep the plasma. One of the important safety systems is the protection against quench events. The quench detection system of W7-X protects the superconducting coils, the superconducting bus bar sections and the high temperature superconductor of the current leads against the damage because of a quench and against the high stress by a fast discharge of the magnet system. Therefore, the present design of the quench detection system (QDS) uses a two-stage safety concept for discharging the magnetic system. This paper describes the present design of the system assembly from the quench detection unit (QDU) for the detection of the quench to the quench detection interface (QDI) to implement the two-stage safety concept.

Preparation of erosion and deposition investigations on plasma facing components in Wendelstein 7-X

Science.gov (United States)

Dhard, C. P.; Balden, M.; Braeuer, T.; Brezinsek, S.; Coenen, J. W.; Dudek, A.; Ehrke, G.; Hathiramani, D.; Klose, S.; König, R.; Laux, M.; Linsmeier, Ch; Manhard, A.; Masuzaki, S.; Mayer, M.; Motojima, G.; Naujoks, D.; Neu, R.; Neubauer, O.; Rack, M.; Ruset, C.; Schwarz-Selinger, T.; Pedersen, T. Sunn; Tokitani, M.; Unterberg, B.; Yajima, M.; W7-X Team1, The

2017-12-01

In the Wendelstein 7-X stellarator with its twisted magnetic geometry the investigation of plasma wall interaction processes in 3D plasma configurations is an important research subject. For the upcoming operation phase i.e. OP1.2, three different types of material probes have been installed within the plasma vessel for the erosion/deposition investigations in selected areas with largely different expected heat load levels, namely, ≤10 MW m-2 at the test divertor units (TDU), ≤500 kW m-2 at the baffles, heat shields and toroidal closures and ≤100 kW m-2 at the stainless steel wall panels. These include 18 exchangeable target elements at TDU, about 30 000 screw heads at graphite tiles and 44 wafer probes on wall panels, coated with marker layers. The layer thicknesses, surface morphologies and the impurity contents were pre-characterized by different techniques and subjected to various qualification tests. The positions of these probes were fixed based on the strike line locations on the divertor predicted by field line diffusion and EMC3/EIRENE modeling calculations for the OP1.2 plasma configurations and availability of locations on panels in direct view of the plasma. After the first half of the operation phase i.e. OP1.2a the probes will be removed to determine the erosion/deposition pattern by post-mortem analysis and replaced by a new set for the second half of the operation phase, OP1.2b.

The implementation of the Wendelstein 7-X control a data acquisition concepts at VUV/XUV overview spectrometers HEXOS

International Nuclear Information System (INIS)

Schacht, Jörg; Pingel, Steffen; Herbst, Uwe; Hennig, Christine; Burhenn, Rainer; Hollfeld, Klaus-Peter; Jordan, Frank

2013-01-01

Highlights: ► Shown in this paper is the implementation of the W7-X CoDaC concept for the HEXOS diagnostic. ► It explains the field, process and supervision level. ► The paper contains descriptions of the slow and fast control and data acquisition stations. ► It introduces the diagnosticians view to CoDaC via high level concept. -- Abstract: HEXOS (high efficiency extreme ultraviolet overview spectrometer) is an optimized set of four efficient VUV/XUV spectrometers. It is suitable for a complete coverage of the wavelength range of interest with sufficient spectral resolution. The spectrometers cover the entire wavelength range of 2.5–160 nm with high performance (up to 9999 spectra at spectra rate of 1000 s −1 ). To operate according to the Wendelstein 7-X (W7-X) control and data acquisition guidelines all necessary concepts for safety, autonomous and subordinated operation, and segment program controlled experiment operation will be implemented at HEXOS. The design of the HEXOS control and data acquisition system and the implementation of the main W7-X control and data acquisition concepts are described. An outlook on the test phase at the TEXTOR (Tokamak Experiment for Technology Oriented Research) device and the commissioning phase at W7-X is given

Overview of physics goals for OP1.2a on Wendelstein 7-X

Science.gov (United States)

Pedersen, Thomas Sunn; W7-X Team

2017-10-01

Wendelstein 7-X achieved, and in many cases exceeded, the pre-defined goals for its first operation phase, OP1.1. Results include core values of Te = 8 keV, Ti = 2 keV and ne>3*1019 m-3 and confinement times of 100-150 ms. The next operation phase, OP1.2a, scheduled to start in fall 2017, features a much more elaborate set of plasma-facing components. 10 inertially cooled graphite test divertor units (TDU) have been installed, as have graphite tiles on all the heat shields and baffles. Upgrades have also been made to heating systems, diagnostics, and particle fueling systems. This will allow for significantly increased pulse lengths, heating power and plasma performance, in particular, higher plasma density, and higher ion temperatures, thereby enabling a much more detailed investigation of the W7-X optimization and significantly higher triple products than achieved in OP1.1. The robustness of the TDU allows for an aggressive exploration of divertor operation scenarios in this phase. The main goals and plans, and, if available, first results of OP1.2a will be presented. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under Grant agreement No 633053.

Overview of the plasma-surface interaction on limiter surfaces in the startup campaign of Wendelstein 7-X

Science.gov (United States)

Winters, V. R.; Brezinsek, S.; Effenberg, F.; Rasinski, M.; Schmitz, O.; Stephey, L.; Biedermann, C.; Dhard, C. P.; Frerichs, H.; Harris, J.; Krychowiak, M.; König, R.; Pedersen, T. Sunn; Wurden, G. A.; the W7-X Team

2017-12-01

The first operational campaign of Wendelstein 7-X (W7-X) provided an excellent environment for the study of plasma-surface interaction (PSI) in a stellarator. In situ spectroscopic analysis via a combined visible/infrared camera system and a filterscope system revealed that the primary erosion zone was correlated with the high heat flux regions on the limiter. This analysis matched to where the erosion zone was found in the post-mortem analysis, which was done with scanning electron microscopy/focused ion beam/electron dispersive x-ray spectroscopy imaging. Additionally, a region of prompt deposition was found to the inside of these high heat flux zones. A region of far scrape-off layer (SOL) deposition was found at the edges of the limiter tiles. All deposition regions were identified by their homogeneous, increased oxygen content compared to the pure carbon makeup of the limiters. Poloidal variation of the impinging heat flux follow the imprint of the 3D SOL flux tubes. In how far this reflects in the PSI will require further analysis and modeling.

Overview of the plasma-surface interaction on limiter surfaces in the startup campaign of Wendelstein 7-X

International Nuclear Information System (INIS)

Winters, V R; Effenberg, F; Schmitz, O; Stephey, L; Frerichs, H; Brezinsek, S; Rasinski, M; Biedermann, C; Dhard, C P; Krychowiak, M; König, R; Pedersen, T Sunn; Harris, J; Wurden, G A

2017-01-01

The first operational campaign of Wendelstein 7-X (W7-X) provided an excellent environment for the study of plasma-surface interaction (PSI) in a stellarator. In situ spectroscopic analysis via a combined visible/infrared camera system and a filterscope system revealed that the primary erosion zone was correlated with the high heat flux regions on the limiter. This analysis matched to where the erosion zone was found in the post-mortem analysis, which was done with scanning electron microscopy/focused ion beam/electron dispersive x-ray spectroscopy imaging. Additionally, a region of prompt deposition was found to the inside of these high heat flux zones. A region of far scrape-off layer (SOL) deposition was found at the edges of the limiter tiles. All deposition regions were identified by their homogeneous, increased oxygen content compared to the pure carbon makeup of the limiters. Poloidal variation of the impinging heat flux follow the imprint of the 3D SOL flux tubes. In how far this reflects in the PSI will require further analysis and modeling. (paper)

Simulation of Targets Feeding Pipe Rupture in Wendelstein 7-X Facility Using RELAP5 and COCOSYS Codes

Science.gov (United States)

Kaliatka, T.; Povilaitis, M.; Kaliatka, A.; Urbonavicius, E.

2012-10-01

Wendelstein nuclear fusion device W7-X is a stellarator type experimental device, developed by Max Planck Institute of plasma physics. Rupture of one of the 40 mm inner diameter coolant pipes providing water for the divertor targets during the "baking" regime of the facility operation is considered to be the most severe accident in terms of the plasma vessel pressurization. "Baking" regime is the regime of the facility operation during which plasma vessel structures are heated to the temperature acceptable for the plasma ignition in the vessel. This paper presents the model of W7-X cooling system (pumps, valves, pipes, hydro-accumulators, and heat exchangers), developed using thermal-hydraulic state-of-the-art RELAP5 Mod3.3 code, and model of plasma vessel, developed by employing the lumped-parameter code COCOSYS. Using both models the numerical simulation of processes in W7-X cooling system and plasma vessel has been performed. The results of simulation showed, that the automatic valve closure time 1 s is the most acceptable (no water hammer effect occurs) and selected area of the burst disk is sufficient to prevent pressure in the plasma vessel.

Transport modeling for W7-X on the basis of W7-AS experimental results

International Nuclear Information System (INIS)

Beidler, C.D.; Geiger, J.; Maassberg, H.; Marushchenko, N.B.; Turkin, Yu.

2008-01-01

Exploratory simulations of plasma confinement in the Wendelstein 7-X (W7-X) stellarator are presented, concentrating on scenarios which simultaneously achieve high temperature and high β (normalized plasma pressure) at the full magnetic field of B=2.5 T. Efficient 1-D transport and ray-tracing codes are combined to provide an approximately self-consistent description of the heating and current drive (ECCD) to be expected from up to 10 MW of electron cyclotron resonance heating (ECRH) in W7-X. Best performance is exhibited in high density (n=1.8x10 20 m -3 ) simulations heated at the second harmonic of the ordinary mode, although control of the magnetic topology at the plasma edge - needed to insure functioning of the island divertor - becomes problematic due to the imbalance of the bootstrap current and ECCD. (author)

First results from protective ECRH diagnostics for Wendelstein 7-X

Science.gov (United States)

Marsen, S.; Corre, Y.; Laqua, H. P.; Moncada, V.; Moseev, D.; Niemann, H.; Preynas, M.; Stange, T.; The W7-X Team

2017-08-01

Wendelstein 7-X (W7-X) is a steady state capable optimised stellarator. The main heating system is electron cyclotron resonance heating (ECRH) operating at 140 GHz providing up to 9 MW microwave power. The power is launched into the machine by front steerable quasi-optical launchers in X- or O-mode. While in X-mode the first pass absorption is 99%, it is only 40... 70% in O-mode. O2-mode heating is forseen for high density operation above the X2 cutoff density of 1.2\\centerdot {{10}20} m-3. A set of diagnostics has been developed to protect the machine from non absorbed ECRH power which can easily damage in vessel components. The non absorbed power hitting the inner wall is measured by waveguides embedded in the first wall (ECA diagnostic). In order to prevent the inner wall from overheating or arcing, a near-infra red sensitive video diagnostic with a dynamic range of 450...1200 °C was integrated in the ECRH launchers. Thermal calculations for the carbon tiles predict a temperature increase above the detection threshold for scenarios of plasma start-up failure or poor absorption on a time scale of 50 ms. However, the temperature increase measured by an IR camera in experiments with failed break down, i.e. no ECRH absorption for up to 50 ms, was only Δ T≈ 70{{~}\\circ} C. In discharges with ≈ 5% transmission the measured temperature increase was comparable. The stray radiation level inside the machine is measured by so called sniffer probes resembling microwave diode detectors which were designed to collect all radiation approaching the probing surface independent of incident angle and polarization. Five sniffer probes are installed at different toroidal positions. They were integrated in the ECRH interlock system. During the first operational phase of W7-X this was the only available plasma interlock system. The signal quality proofed to be high enough for a reliable termination in case of poor absorption. After a breakdown phase of 10 ms, the sniffer

A near infra-red video system as a protective diagnostic for electron cyclotron resonance heating operation in the Wendelstein 7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Preynas, M.; Laqua, H. P.; Marsen, S.; Reintrog, A. [Max-Planck-Institut für Plasmaphysik (IPP), D-17491 Greifswald (Germany); Corre, Y.; Moncada, V.; Travere, J.-M. [IRFM, CEA-Cadarache, 13108 Saint Paul lez Durance Cedex (France)

2015-11-15

The Wendelstein 7-X stellarator is a large nuclear fusion device based at Max-Planck-Institut für Plasmaphysik in Greifswald in Germany. The main plasma heating system for steady state operation in W7-X is electron cyclotron resonance heating (ECRH). During operation, part of plama facing components will be directly heated by the non-absorbed power of 1 MW rf beams of ECRH. In order to avoid damages of such components made of graphite tiles during the first operational phase, a near infra-red video system has been developed as a protective diagnostic for safe and secure ECRH operation. Both the mechanical design housing the camera and the optical system are very flexible and respect the requirements of steady state operation. The full system including data acquisition and control system has been successfully tested in the vacuum vessel, including on-line visualization and data storage of the four cameras equipping the ECRH equatorial launchers of W7-X.

Wall conditioning by ECRH discharges and He-GDC in the limiter phase of Wendelstein 7-X

Science.gov (United States)

Wauters, T.; Brakel, R.; Brezinsek, S.; Dinklage, A.; Goriaev, A.; Laqua, H. P.; Marsen, S.; Moseev, D.; Stange, T.; Schlisio, G.; Pedersen, T. Sunn; Volzke, O.; Wenzel, U.; the W7-X Team

2018-06-01

Wendelstein 7-X (W7-X) relies on wall conditioning to control the density and the impurity content of the plasma. Wall conditioning in the first operation campaign of W7-X consisted of baking at 150 °C during 1 week prior to operation, glow discharge conditioning (GDC) in helium (He) and electron cyclotron resonance heating (ECRH) discharges. Additionally, the usage of He-GDC was limited to avoid sputtering and migration of metallic plasma facing components. This presented a unique opportunity for studying the applicability of ECRH discharges for initial wall conditioning on a stellarator, albeit in the carbon limiter configuration. A single envelope curve is observed in the normalised outgassing data that takes into account all ECRH discharges. This illustrates that the majority of discharges operates at the limits of a radiative collapse. Hydrogen recycling dominated the fuelling of ECRH discharges throughout while CO outgassing was found strongest at the start of the campaign. A reduction of recycling was observed throughout the campaign. Temporarily depleting the walls from H and impurities was possible by He-GDC. It was shown that the recycling coefficient in -ECRH plasmas could be reduced and the pulse duration significantly extended by He-’recovery’ ECRH plasmas. Good wall conditions were defined by normalised outgassing values below mbar kJ‑1. In absence of -GDC, more than 311 cumulated discharge seconds of ECRH discharges are needed for obtaining lasting low outgassing levels. A release model with two trapping reservoirs could reproduce the normalised outgassing trend, including ECRH and GDC plasma wall interactions.

Study of neoclassical transport and bootstrap current for W7-X in the 1/upsilon regime, using results from the PIES code

International Nuclear Information System (INIS)

Nemov, V V; Kalyuzhnyj, V N; Kasilov, S V; Drevlak, M; Nuehrenberg, J; Kernbichler, W; Reiman, A; Monticello, D

2004-01-01

For the magnetic field of the Wendelstein 7-X (W7-X) standard high-mirror configuration, computed by the PIES code, taking into account real coil geometry, neoclassical transport and bootstrap current are analysed in the 1/upsilon regime using methods based on the integration along magnetic field lines in a given magnetic field. The zero beta and (beta) = 1% cases are studied. The results are compared to the corresponding results for the vacuum magnetic field directly produced by modular coils. A significant advantage of W7-X over a conventional stellarator resulting from reduced neoclassical transport and from reduced bootstrap current follows from the computations although the neoclassical transport is somewhat larger than that previously obtained for the ideal W7-X model configuration

Connecting programmable logic controllers (PLC) to control and data acquisition a comparison of the JET and Wendelstein 7-X approach

International Nuclear Information System (INIS)

Hennig, Christine; Kneupner, Klaus; Kinna, David

2012-01-01

Highlights: ► We describe 2 ways connecting PLCs to fusion control and data acquisition software. ► At W7-X standardization of the PLC type eases the maintenance of the software. ► At JET PLCs are interfaced with a daemon that hides the PLC specific part. ► There is potential to unify the approaches towards a common fusion PLC interface. - Abstract: The use of programmable logic controllers (PLC) for automation of electromechanical processes is an industrial control system technology. It is more and more in use within the fusion community. Traditionally PLC based systems are operated and maintained using proprietary SCADA systems (supervisory control and data acquisition). They are hardly ever integrated with the fusion control and data acquisition systems. An overview of the state of the art in fusion is given in the article. At JET an inhouse “black box protocol” approach has been developed to communicate with any external system via a dedicated http based protocol. However, a PLC usually cannot be modified to implement this special protocol. Hence, a software layer has been developed that interfaces a PLC by implementing the PLC specific communication part on one side and the black box protocol part on the other side. The software is completely data driven i.e. editing the data structure changes the logic accordingly. It can be tested using the web capability of the black box protocol. Multiple PLC types from different vendors are supported, thus multiple protocols to interface the PLC are in use. Depending on the PLC type and available tools it can be necessary to program the PLC accordingly. Wendelstein 7-X uses another approach. For every single PLC a dedicated communication from and to CoDaC is implemented. This communication is projected (programmed) in the PLC and configurable (data driven) on the CoDaC side. The protocol is UDP based and observed via timeout mechanisms. The use of PLCs for Wendelstein 7-X is standardized. Therefore a single

Connecting programmable logic controllers (PLC) to control and data acquisition a comparison of the JET and Wendelstein 7-X approach

Energy Technology Data Exchange (ETDEWEB)

Hennig, Christine, E-mail: Christine.Hennig@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik, Wendelsteinstrasse 1, 17491 Greifswald (Germany); Kneupner, Klaus; Kinna, David [JET-EFDA, Culham Science Centre, OX14 3DB Abingdon (United Kingdom)

2012-12-15

Highlights: Black-Right-Pointing-Pointer We describe 2 ways connecting PLCs to fusion control and data acquisition software. Black-Right-Pointing-Pointer At W7-X standardization of the PLC type eases the maintenance of the software. Black-Right-Pointing-Pointer At JET PLCs are interfaced with a daemon that hides the PLC specific part. Black-Right-Pointing-Pointer There is potential to unify the approaches towards a common fusion PLC interface. - Abstract: The use of programmable logic controllers (PLC) for automation of electromechanical processes is an industrial control system technology. It is more and more in use within the fusion community. Traditionally PLC based systems are operated and maintained using proprietary SCADA systems (supervisory control and data acquisition). They are hardly ever integrated with the fusion control and data acquisition systems. An overview of the state of the art in fusion is given in the article. At JET an inhouse 'black box protocol' approach has been developed to communicate with any external system via a dedicated http based protocol. However, a PLC usually cannot be modified to implement this special protocol. Hence, a software layer has been developed that interfaces a PLC by implementing the PLC specific communication part on one side and the black box protocol part on the other side. The software is completely data driven i.e. editing the data structure changes the logic accordingly. It can be tested using the web capability of the black box protocol. Multiple PLC types from different vendors are supported, thus multiple protocols to interface the PLC are in use. Depending on the PLC type and available tools it can be necessary to program the PLC accordingly. Wendelstein 7-X uses another approach. For every single PLC a dedicated communication from and to CoDaC is implemented. This communication is projected (programmed) in the PLC and configurable (data driven) on the CoDaC side. The protocol is UDP based and

Design improvement of the target elements of Wendelstein 7-X divertor

International Nuclear Information System (INIS)

Boscary, J.; Peacock, A.; Friedrich, T.; Greuner, H.; Böswirth, B.; Tittes, H.; Schulmeyer, W.; Hurd, F.

2012-01-01

Highlights: ► Improvement of the cooling structure design. ► Improvement of the CFC tile arrangement at the element end. ► Design and fabrication validated with high heat flux testing. ► Selected solution removes stationary heat load of 5 MW/m 2 and 2 MW/m 2 on the top and on the side facing the pumping gap of the element, respectively. - Abstract: The actively cooled high-heat flux divertor of the Wendelstein 7-X stellarator consists of individual target elements made of a water-cooled CuCrZr copper alloy heat sink armored with CFC tiles. The so-called “bi-layer” technology developed in collaboration with the company Plansee for the bonding of the tiles onto the heat sink has reliably demonstrated the removal of the specified heat load of 10 MW/m 2 in the central area of the divertor. However, due to geometrical constraints, the loading performance at the ends of the elements is reduced compared to the central part. Design modifications compatible with industrial processes have been made to improve the cooling capabilities at this location. These changes have been validated during test campaigns of full-scale prototypes carried out in the neutral beam test facility GLADIS. The tested solution can remove reliably the stationary heat load of 5 MW/m 2 and 2 MW/m 2 on the top and on the side of the element, respectively. The results of the testing allowed the release of the design and fabrication processes for the next manufacturing phase of the target elements.

Change of manufacturing technique for the W7-X nonplanar coil cases

International Nuclear Information System (INIS)

Gehring, M.; Schaefer, P.; Herrmann, K.D.; Scheller, H.

2001-01-01

The geometry of the coil cases of the nonplanar coil system for the Wendelstein 7-X (W7-X) experiment (Sapper, The superconducting magnet system for the W7-X stellarator. Proceedings 12th Topical Meeting on the Fusion Technology) was changed to a more complex shape compared to the DEMO Coil case (Kronhardt et al., 1998. Proceedings of the 20th SOFT (1998) 731-734). Therefore the manufacturing technique developed for the DEMO Coil case cannot be used for the series production of 50 coils. For the final design of the coil cases, investigations were performed to find a technique suitable for manufacturing the cases within the required geometrical tolerances and mechanical characteristics. In order to qualify the manufacturing technique a complete half case was cast and machined afterwards. The casting procedure was optimised with respect to the geometrical accuracy and the mechanical characteristics at 4.2 K. Measurements of the yield strength, the tensile strength, the elongation, and the Young's modulus were performed at room- and cryo-temperature (4 and 7 K). The influence of the heat treatment, the annealing temperature and the size of the casting on the mechanical values is shown. The requirements on the stainless steel are a yield strength of 800 MPa at 4 K and an elongation at fracture of >25%. The magnetic permeability has to be <1.01. Furthermore the welding properties of the case material were investigated. The development program showed that casting of complete case half shells is a feasible manufacturing technique for the series production of the Wendelstein 7-X nonplanar coil cases

Finite element based design optimization of WENDELSTEIN 7-X divertor components under high heat flux loading

International Nuclear Information System (INIS)

Plankensteiner, A.; Leuprecht, A.; Schedler, B.; Scheiber, K.-H.; Greuner, H.

2007-01-01

In the divertor of the nuclear fusion experiment WENDELSTEIN 7-X (W7-X) plasma facing high heat flux target elements have to withstand severe loading conditions. The thermally induced mechanical stressing turns out to be most critical with respect to lifetime predictions of the target elements. Therefore, different design variants of those CFC flat tile armoured high heat flux components have been analysed via the finite element package ABAQUS aiming at derivation of an optimized component design under high heat flux conditions. The investigated design variants comprise also promising alterations in the cooling channel design and castellation of the CFC flat tiles which, however, from a system integration and manufacturing standpoint of view, respectively, are evaluated to be critical. Therefore, the numerical study as presented here mainly comprises a reference variant that is comparatively studied with a variant incorporating a bi-layer-type AMC-Cu/OF-Cu interlayer at the CFC/Cu-interface. The thermo-mechanical material characteristics are accounted for in the finite element models with elastic-plastic properties being assigned to the metallic sections CuCrZr, AMC-Cu and OF-Cu, respectively, and orthotropic nonlinear-elastic properties being used for the CFC sections. The calculated temporal and spatial evolution of temperatures, stresses, and strains for the individual design variants are evaluated with special attention being paid to stress measures, plastic strains, and damage parameters indicating the risk of failure of CFC and the CFC/Cu-interface, respectively. This way the finite element analysis allows to numerically derive an optimized design variant within the framework of expected operating conditions in W7-X

Experience with High Voltage Tests of the W7-X Magnets in Paschen-Minimum Conditions

International Nuclear Information System (INIS)

Petersen-Zarling, B.M.; Risse, K.; Viebke, H.; Gustke, D.; Ehmler, H.; Baldzuhn, J.; Sborchia, C.; Scheller, H.

2006-01-01

The W7-X machine is a low-shear stellarator of the Wendelstein line, which is being assembled at the IPP Branch Institute of Greifswald, Germany. The machine features a superconducting magnet system with 50 non-planar and 20 planar magnets operated at about 6 T and discharged with peak voltage levels up to 6 kV. Following the factory tests, the magnets are delivered to CEA Saclay, France, for the final acceptance tests at cryogenic condition. A series of high voltage tests in air and vacuum are part of the final acceptance test. During these tests the quality of the insulation, especially the hand-wrapped ground insulation in the termination area, has proven not to be adequate. In order to improve the reliability of the insulation system and detect defects for early repair, high voltage tests in reduced pressure of air (Paschen-minimum conditions) have been added as part of the factory acceptance procedure. This has been implemented in the vacuum chambers of BNN/Ansaldo for the test of the 50 non-planar coils, while other tests have been carried out at CEA/Saclay after cold testing. IPP has also installed a vacuum tank to perform Paschen tests during the preparation of all the coils for assembly, including also the 20 planar coils which cannot be tested at the manufacturer Tesla. These tests have proven to be a powerful tool to detect hidden insulation defects and void/cavities in the primary impregnation system, which could not be detected otherwise with the standard high voltage tests. This paper will summarize the background and experience accumulated in about 2 years of Paschen tests on the W7-X coils, including a description of the equipment, main results and statistics, weak points detected and repaired on the coils, and possibilities of improvements in the development and production of the W7-X magnets. The importance and the need of Paschen tests as part of the acceptance procedure for superconducting magnets to be used in future projects will also be

Plasma performance of Wendelstein 7-AS with the new boundary-island divertor modules

International Nuclear Information System (INIS)

McCormick, K.; Grigull, P.; Burhenn, R.; Brakel, R.; Ehmler, H.; Feng, Y.; Gadelmeier, F.; Giannone, L.; Hildebrandt, D.; Hirsch, M.; Jaenicke, R.; Kisslinger, J.; Klinger, T.; Klose, S.; Knauer, J.P.; Konig, R.; Kuhner, G.; Laqua, H.P.; Naujoks, D.; Niedermeyer, H.; Pasch, E.; Ramasubramanian, N.; Rust, N.; Sardei, F.; Wagner, F.; Weller, A.; Wenzel, U.; Werner, A.

2002-01-01

A promising new plasma operational regime on the Wendelstein stellarator W7-AS has been discovered. It is extant above a threshold density and characterized by flat density profiles, high energy- and low impurity-confinement times and edge-localized radiation. Impurity accumulation is avoided. Quasi-stationary discharges with line-averaged densities n e to 4x10 20 m -3 , radiation levels to 90%, and partial plasma detachment at the divertor target plates can be simultaneously realized. Energy confinement is up to twice that predicted by a conventional scaling. Copyright (2002) Australian National University- Research School of Physical Sciences and Engineering

Advanced neutral gas diagnostics for magnetic confinement devices

International Nuclear Information System (INIS)

Wenzel, U.; Schlisio, G.; Marquardt, M.; Pedersen, T.S.; Kremeyer, T.; Schmitz, O.; Mackie, B.; Maisano-Brown, J.

2017-01-01

For the study of particle exhaust in nuclear fusion devices the neutral pressure must be measured in strong magnetic fields. We describe as an example the neutral pressure gauges in the Wendelstein 7-X stellarator. Two types are used: hot cathode ionization gauges (or ASDEX pressure gauges) and Penning gauges. We show some results from the first experimental campaign. The main problems were runtime effects and the failure of some ASDEX pressure gauges. To improve the reliability we integrated a new LaB 6 electron emitter into the ASDEX pressure gauges. In addition, a special Penning gauge without permanent magnets was developed in order to operate Penning gauges near the plasma edge. These new pressure gauges will be used in the upcoming campaign of Wendelstein 7-X.

Lessons learned from the manufacture of the W7-X planar coils

Science.gov (United States)

Viebke, H.; Gustke, D.; Rummel, T.; Sborchia, C.; Schroeder, R.; Williams, D.; Bates, S.; Leigh, B.; Winter, R.

2006-06-01

WENDELSTEIN 7-X (W7-X) is a superconducting stellarator. The planar coils are in charge to modify the magnetic filed configuration of the W7-X. The major challenges during manufacturing were the fabrication of the cable-in-conduit conductor, the accuracy of the coil cases after welding and machining and the development of electrical joints with a resistance below 1 nΩ. Leaks were detected during repetitive in the case cooling system, which were caused by stress corrosion cracking. High voltage tests in a reduced vacuum environment (Paschen conditions) revealed that the insulation had to be reinforced and the quench detection wires had to be exchanged. This paper gives an overview about the main technical challenges of the planar coils and the lessons learned during production.

Lessons learned from the manufacture of the W7-X planar coils

International Nuclear Information System (INIS)

Viebke, H; Gustke, D; Rummel, T; Sborchia, C; Schroeder, R; Williams, D; Bates, S; Leigh, B; Winter, R

2006-01-01

WENDELSTEIN 7-X (W7-X) is a superconducting stellarator. The planar coils are in charge to modify the magnetic filed configuration of the W7-X. The major challenges during manufacturing were the fabrication of the cable-in-conduit conductor, the accuracy of the coil cases after welding and machining and the development of electrical joints with a resistance below 1 nΩ. Leaks were detected during repetitive in the case cooling system, which were caused by stress corrosion cracking. High voltage tests in a reduced vacuum environment (Paschen conditions) revealed that the insulation had to be reinforced and the quench detection wires had to be exchanged. This paper gives an overview about the main technical challenges of the planar coils and the lessons learned during production

Spatial distribution of turbulence in the Wendelstein 7-AS stellarator (invited paper)

DEFF Research Database (Denmark)

Basse, N.P.; Michelsen, Poul; Zoletnik, S.

2002-01-01

In this paper measurements of short wavelength electron density fluctuations using collective scattering of infrared light are presented. The Wendelstein 7-AS (W7-AS) stellarator (Renner H et al 1989 Plasma Phys. Control. Fusion 31 1579) and the diagnostic are briefly described. A series of plasm...

Prototyping phase of the high heat flux scraper element of Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Boscary, J., E-mail: jean.boscary@ipp.mpg.de [Max Planck Institute for Plasma Physics, Garching (Germany); Greuner, H. [Max Planck Institute for Plasma Physics, Garching (Germany); Ehrke, G. [Max Planck Institute for Plasma Physics, Greifswald (Germany); Böswirth, B.; Wang, Z. [Max Planck Institute for Plasma Physics, Garching (Germany); Clark, E. [University of Tennessee, Knoxville (United States); Lumsdaine, A. [Oak Ridge National Laboratory, USA National Laboratory, Oak Ridge, Tennessee (United States); Tretter, J. [Max Planck Institute for Plasma Physics, Garching (Germany); McGinnis, D.; Lore, J. [Oak Ridge National Laboratory, USA National Laboratory, Oak Ridge, Tennessee (United States); Ekici, K. [University of Tennessee, Knoxville (United States)

2016-11-01

Highlights: • Aim of scraper element: reduction of heat loads on high heat flux divertor ends. • Design: actively water-cooled for 20 MW/m{sup 2} local heat loads. • Technology: CFC NB31 monoblocks bonded by HIP to CuCrZr cooling tube. • Successful high heat flux testing up to 20 MW/m{sup 2}. - Abstract: The water-cooled high heat flux scraper element aims to reduce excessive heat loads on the target element ends of the actively cooled divertor of Wendelstein 7-X. Its purpose is to intercept some of the plasma fluxes both upstream and downstream before they reach the divertor surface. The scraper element has 24 identical plasma facing components (PFCs) divided into 6 modules. One module has 4 PFCs hydraulically connected in series by 2 water boxes. A PFC, 247 mm long and 28 mm wide, has 13 monoblocks made of CFC NB31 bonded by hot isostatic pressing onto a CuCrZr cooling tube equipped with a copper twisted tape. 4 full-scale prototypes of PFCs have been successfully tested in the GLADIS facility up to 20 MW/m{sup 2}. The difference observed between measured and calculated surface temperatures is probably due to the inhomogeneity of CFC properties. The design of the water box prototypes has been detailed to allow the junction between the cooling pipe of the PFCs and the water boxes by internal orbital welding. The prototypes are presently under fabrication.

Design of the Wendelstein 7-X inertially cooled Test Divertor Unit Scraper Element

Energy Technology Data Exchange (ETDEWEB)

Lumsdaine, Arnold, E-mail: lumsdainea@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Boscary, Jean [Max Planck Institute for Plasma Physics, Garching (Germany); Fellinger, Joris [Max Planck Institute for Plasma Physics, Greifswald (Germany); Harris, Jeff [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Hölbe, Hauke; König, Ralf [Max Planck Institute for Plasma Physics, Greifswald (Germany); Lore, Jeremy; McGinnis, Dean [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Neilson, Hutch; Titus, Peter [Princeton Plasma Physics Lab, Princeton, NJ (United States); Tretter, Jörg [Max Planck Institute for Plasma Physics, Garching (Germany)

2015-10-15

Highlights: • The justification for the installation of the Test Divertor Unit Scraper Element is given. • Specially designed operational scenarios for the component are presented. • Plans for the design of the component are detailed. - Abstract: The Wendelstein 7-X stellarator is scheduled to begin operation in 2015, and to achieve full power steady-state operation in 2019. Computational simulations have indicated that for certain plasma configurations in the steady-state operation, the ends of the divertor targets may receive heat fluxes beyond their qualified technological limit. To address this issue, a high heat-flux “scraper element” (HHF-SE) has been designed that can protect the sensitive divertor target region. The surface profile of the HHF-SE has been carefully designed to meet challenging engineering requirements and severe spatial limitations through an iterative process involving physics simulations, engineering analysis, and computer aided design rendering. The desire to examine how the scraper element interacts with the plasma, both in terms of how it protects the divertor, and how it affects the neutral pumping efficiency, has led to the consideration of installing an inertially cooled version during the short pulse operation phase. This Test Divertor Unit Scraper Element (TDU-SE) would replicate the surface profile of the HHF-SE. The design and instrumentation of this component must be completed carefully in order to satisfy the requirements of the machine operation, as well as to support the possible installation of the HHF-SE for steady-state operation.

Feasibility of a Heavy Ion Beam Probe for W7-X

Science.gov (United States)

Crowley, T. P.; Demers, D. R.; Fimognari, P. J.; Grulke, O.; Laube, R.

2017-10-01

A feasibility study of a Heavy Ion Beam Probe (HIBP) diagnostic for the Wendelstein 7-X (W7-X) superconducting stellarator, incorporating the accelerator and energy analyzer (currently in Greifswald) from the 2 MeV TEXT-U HIBP, is being carried out. The study's results are positive: beam trajectory simulations in the W7-X standard magnetic configuration, with central densities up to 1020 m-3, predict that it will be possible to measure the equilibrium plasma potential and Er at all radii, and simultaneously measure temporally and spatially resolved fluctuations of ne and potential for r / a >0.5. This will provide a unique capability to advance understanding of neoclassical and turbulent particle and energy transport in W7-X. Within this feasibility study, the beam is injected and detected through the K11 and N11 ports respectively, and the toroidal magnetic field is in the ` + φ ' direction. Additional beam simulations reveal that most radii can be accessed in 7 other paradigm magnetic configurations. It's anticipated that electrostatic beam steering suitable for studying all these configurations is plausible; it will have plate dimensions comparable to TEXT-U's with smaller electric fields and higher voltages. Initial estimates of anticipated heat load from the W7-X plasma on the steering systems indicate it will be significant, but tractable. Our conclusion from these studies is that an HIBP diagnostic for W7-X is feasible. This work is supported by US DoE Award DE-SC0013918.

First results of the multi-purpose real-time processing video camera system on the Wendelstein 7-X stellarator and implications for future devices

Science.gov (United States)

Zoletnik, S.; Biedermann, C.; Cseh, G.; Kocsis, G.; König, R.; Szabolics, T.; Szepesi, T.; Wendelstein 7-X Team

2018-01-01

A special video camera has been developed for the 10-camera overview video system of the Wendelstein 7-X (W7-X) stellarator considering multiple application needs and limitations resulting from this complex long-pulse superconducting stellarator experiment. The event detection intelligent camera (EDICAM) uses a special 1.3 Mpixel CMOS sensor with non-destructive read capability which enables fast monitoring of smaller Regions of Interest (ROIs) even during long exposures. The camera can perform simple data evaluation algorithms (minimum/maximum, mean comparison to levels) on the ROI data which can dynamically change the readout process and generate output signals. Multiple EDICAM cameras were operated in the first campaign of W7-X and capabilities were explored in the real environment. Data prove that the camera can be used for taking long exposure (10-100 ms) overview images of the plasma while sub-ms monitoring and even multi-camera correlated edge plasma turbulence measurements of smaller areas can be done in parallel. These latter revealed that filamentary turbulence structures extend between neighboring modules of the stellarator. Considerations emerging for future upgrades of this system and similar setups on future long-pulse fusion experiments such as ITER are discussed.

Energetic Ion Loss Diagnostic for the Wendelstein 7-AS Stellarator

International Nuclear Information System (INIS)

Darrow, D. S.; Werner, A.; Weller, A.

2000-01-01

A diagnostic to measure the loss of energetic ions from the Wendelstein 7-AS (W7-AS) stellarator has been built. It is capable of measuring losses of both neutral beam ions and energetic ions arising from ion cyclotron resonant heating. The probe can measure losses of both clockwise and counterclockwise-going energetic ions simultaneously, and accepts a wide range of pitch angles in both directions. Initial measurements by the diagnostic are reported

Production management and quality assurance for the fabrication of the In-Vessel Components of the stellarator Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Li, C., E-mail: chuanfei.li@ipp.mpg.de; Boscary, J.; Dekorsy, N.; Junghanns, P.; Mendelevitch, B.; Peacock, A.; Pirsch, H.; Sellmeier, O.; Springer, J.; Stadler, R.; Streibl, B.

2014-10-15

Highlights: • Thousand parts for the divertor, first wall, cooling supply and diagnostics as W7-X In-Vessel Components. • Database building including part and assembly data, work and capacity organization, quality assurance documents. • Production management system to organize the fabrication and the associated quality assurance. • Successful use of an efficient and flexible product planning and scheduling tool for W7-X In-Vessel Components. - Abstract: The In-Vessel Components (IVC) of the stellarator Wendelstein 7-X consist of the divertor components and the first wall (FW) with their internal water cooling supply and a set of diagnostics. Due to the significant amount of different components, including many variants, a tool called Production Managing System (PMS) has been developed to organize the fabrication and the associated quality assurance. The PMS works by building a database containing the basic parts and assembly data, manufacturing and quality control plans, and available machine capacity. The creation of this database is based mainly on the parts lists, the manufacturing drawings, and details of the working flow organization. As a consequence of the learning process and technical adjustments during the design and manufacturing phase, the database needed to be permanently updated. Therefore an interface tool to optimize the data preparation has been developed. PMS has been demonstrated to be an efficient tool to support the IVC production activities providing reliable planning estimates, easily adaptable to problems encountered during the fabrication and provided a basis for the integration of quality assurance requirements.

Production management and quality assurance for the fabrication of the In-Vessel Components of the stellarator Wendelstein 7-X

International Nuclear Information System (INIS)

Li, C.; Boscary, J.; Dekorsy, N.; Junghanns, P.; Mendelevitch, B.; Peacock, A.; Pirsch, H.; Sellmeier, O.; Springer, J.; Stadler, R.; Streibl, B.

2014-01-01

Highlights: • Thousand parts for the divertor, first wall, cooling supply and diagnostics as W7-X In-Vessel Components. • Database building including part and assembly data, work and capacity organization, quality assurance documents. • Production management system to organize the fabrication and the associated quality assurance. • Successful use of an efficient and flexible product planning and scheduling tool for W7-X In-Vessel Components. - Abstract: The In-Vessel Components (IVC) of the stellarator Wendelstein 7-X consist of the divertor components and the first wall (FW) with their internal water cooling supply and a set of diagnostics. Due to the significant amount of different components, including many variants, a tool called Production Managing System (PMS) has been developed to organize the fabrication and the associated quality assurance. The PMS works by building a database containing the basic parts and assembly data, manufacturing and quality control plans, and available machine capacity. The creation of this database is based mainly on the parts lists, the manufacturing drawings, and details of the working flow organization. As a consequence of the learning process and technical adjustments during the design and manufacturing phase, the database needed to be permanently updated. Therefore an interface tool to optimize the data preparation has been developed. PMS has been demonstrated to be an efficient tool to support the IVC production activities providing reliable planning estimates, easily adaptable to problems encountered during the fabrication and provided a basis for the integration of quality assurance requirements

Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

International Nuclear Information System (INIS)

Peng, X.B.; Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F.; Vliegenthart, W.

2014-01-01

Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion

Thermo-mechanical behavior of retro-reflector and resulting parallelism error of laser beams for Wendelstein 7-X interferometer

Energy Technology Data Exchange (ETDEWEB)

Peng, X.B., E-mail: pengxb@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, 230031 Hefei Anhui (China); Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Hirsch, M.; Köppen, M.; Fellinger, J.; Bykov, V.; Schauer, F. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Vliegenthart, W. [TNO, Stieltjesweg 1, P.O. Box 2600, 2628 CK Delft (Netherlands)

2014-04-15

Highlights: • The criterion for thermo-mechanical design of W7-X interferometer retro-reflector. • Thermo-mechanical analysis of retro-reflector with two different methods. • The most flexible part in the retro-reflector is spring washer. • Calculation of parallelism error between the incoming and reflected laser beams. • The parallelism error is much lower than the design limit 28 arcs. - Abstract: A 10 channels interferometer will be used in the Wendelstein 7-X (W7-X) for plasma density control and density profile tracking with laser beams passing through the plasma. Due to complex shape of non-planar modular coils and divertor structure, there are no large poloidally opposite ports on the plasma vessel (PV). Therefore 10 in-vessel Corner Cube Retro-reflectors (CCRs) will be used. The CCRs are integrated in the water cooled heat shield and exposed directly to thermal loads from plasma radiation. Thermo-mechanical issues are very important for the design of the CCR because deformation and flatness as well as mutual angles of the three reflecting surfaces would affect the parallelism of the laser beams and the functionality of the interferometer. Intensive work has been done to explore a suitable design for the CCR concerning thermo-mechanical behavior. Previous studies Ye et al. (2008, 2009) and Köppen et al. (2011) focused on structural optimization to decrease thermal stress in the reflecting plates under the thermal loads, and on computation and check of curvature radii of the deformed reflecting surfaces with the design criterion that the curvature radius must be bigger than 200 m. The paper presents detailed thermo-mechanical analysis of the current improved CCR under thermal loads and bolt preloads. The results of the thermo-mechanical analysis were used for the study of the resulting parallelism error of the laser beams with newly developed and more reasonable design criterion.

Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited).

Science.gov (United States)

Krychowiak, M; Adnan, A; Alonso, A; Andreeva, T; Baldzuhn, J; Barbui, T; Beurskens, M; Biel, W; Biedermann, C; Blackwell, B D; Bosch, H S; Bozhenkov, S; Brakel, R; Bräuer, T; Brotas de Carvalho, B; Burhenn, R; Buttenschön, B; Cappa, A; Cseh, G; Czarnecka, A; Dinklage, A; Drews, P; Dzikowicka, A; Effenberg, F; Endler, M; Erckmann, V; Estrada, T; Ford, O; Fornal, T; Frerichs, H; Fuchert, G; Geiger, J; Grulke, O; Harris, J H; Hartfuß, H J; Hartmann, D; Hathiramani, D; Hirsch, M; Höfel, U; Jabłoński, S; Jakubowski, M W; Kaczmarczyk, J; Klinger, T; Klose, S; Knauer, J; Kocsis, G; König, R; Kornejew, P; Krämer-Flecken, A; Krawczyk, N; Kremeyer, T; Książek, I; Kubkowska, M; Langenberg, A; Laqua, H P; Laux, M; Lazerson, S; Liang, Y; Liu, S C; Lorenz, A; Marchuk, A O; Marsen, S; Moncada, V; Naujoks, D; Neilson, H; Neubauer, O; Neuner, U; Niemann, H; Oosterbeek, J W; Otte, M; Pablant, N; Pasch, E; Sunn Pedersen, T; Pisano, F; Rahbarnia, K; Ryć, L; Schmitz, O; Schmuck, S; Schneider, W; Schröder, T; Schuhmacher, H; Schweer, B; Standley, B; Stange, T; Stephey, L; Svensson, J; Szabolics, T; Szepesi, T; Thomsen, H; Travere, J-M; Trimino Mora, H; Tsuchiya, H; Weir, G M; Wenzel, U; Werner, A; Wiegel, B; Windisch, T; Wolf, R; Wurden, G A; Zhang, D; Zimbal, A; Zoletnik, S

2016-11-01

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.

Towards assembly completion and preparation of experimental campaigns of Wendelstein 7-X in the perspective of a path to a stellarator fusion power plant

Energy Technology Data Exchange (ETDEWEB)

Klinger, T., E-mail: thomas.klinger@ipp.mpg.de; Baylard, C.; Beidler, C.D.; Boscary, J.; Bosch, H.S.; Dinklage, A.; Hartmann, D.; Helander, P.; Maßberg, H.; Peacock, A.; Pedersen, T.S.; Rummel, T.; Schauer, F.; Wegener, L.; Wolf, R.

2013-10-15

Graphical abstract: The superconducting stellarator device Wendelstein 7-X, currently under construction, is the key device for the proof of stellarator optimization principles. To establish the optimized stellarator as a serious candidate for a fusion reactor, reactor-relevant plasma parameters must be achieved in fully integrated steady-state scenarios. After more than 10 years of construction time, the completion of the device is now approaching rapidly (mid-2014). We discuss the most important lessons learned during the device assembly, first experiences with coming major work packages, and the physics program of the first two operation phases. The concept of a stellarator fusion power plant is outlined, too. Highlights: • The superconducting stellarator device Wendelstein 7-X is presented. • The optimized stellarator may be a serious candidate for a fusion reactor. • Reactor-relevant plasma parameters must be achieved in integrated steady-state scenarios. • We discuss the most important lessons learned during the device assembly. • We discuss first experiences with coming major work packages. • We discuss the physics program of the first two operation phases. • The concept of a stellarator fusion power plant is outlined. -- Abstract: The superconducting stellarator device Wendelstein 7-X, currently under construction, is the key device for the proof of stellarator optimization principles. To establish the optimized stellarator as a serious candidate for a fusion reactor, reactor-relevant dimensionless plasma parameters must be achieved in fully integrated steady-state scenarios. After more than 10 years of construction time, the completion of the device is now approaching rapidly (mid-2014). We discuss the most important lessons learned during the device assembly and first experiences with coming major work packages. Those are (a) assembly of about 2500 large, water-cooled, 3d-shaped in-vessel component elements; (b) assembly of in total 14

Vacuum magnetic field and modular coil system of the advanced stellarator Wendelstein VII-AS

International Nuclear Information System (INIS)

Rau, F.; Kisslinger, J.; Wobig, H.

1982-06-01

The vacuum field and the modular coils of the advanced stellarator WENDELSTEIN VII-AS are described. Each of the five field periods contains 9 different twisted coils, one of them with increased dimensions and current in order to provide sufficient access. The standard vacuum field configuration (B=3 T, t=0.39, aspect ratio approx. equal to 10, low shear, and magnetic well) can be varied by toroidal and vertical fields, or by changing independently the current in the large special coils. From a study of magnetic field perturbations some estimates are derived for the admissible coil tolerances. (orig.)

Thermo-mechanical tests on W7-X current lead flanges

International Nuclear Information System (INIS)

Dhard, Chandra Prakash; Rummel, Thomas; Zacharias, Daniel; Bykov, Victor; Moennich, Thomas; Buscher, Klaus-Peter

2013-01-01

Highlights: • There are significant mechanical loads on the cryostat and radial flanges for W7-X current leads. • These are due to evacuation of W7-X cryostat, cool-down of cold mass, electro-magnetic forces and self weight of leads. • The actual mechanical loads were reduced to simplify the experimental set-up. • The tests were carried out on mock-up flanges test assembly at ambient temperature and at 77 K. • The thermo-mechanical tests on W7-X current lead flanges validate the design and joints of these flanges to the leads. -- Abstract: Fourteen pieces of high temperature superconducting current leads (CL) arranged in seven pairs, will be installed on the outer vessel of Wendelstein 7-X (W7-X) stellarator. In order to support the CL, it is provided with two glass fiber reinforce plastic (GFRP) flanges, namely, the lower cryostat flange (CF) remaining at room temperature and upper radial flange (RF) at about 5 K. Both the flanges i.e. CF and RF experience high mechanical loads with respect to the CL, due to the evacuation of W7-X cryostat, cool-down of cold mass including the CL, electro-magnetic forces due to current and plasma operations and self weight of CL. In order to check the integrity of these flanges for such mechanical loads, thermo-mechanical tests were carried out on these flanges at room temperatures and at liquid nitrogen (LN2) temperatures. The details of test set-up, results and modeling are described in the paper

Magnetic configuration effects on the edge heat flux in the limiter plasma on W7-X measured using the infrared camera and the combined probe

Science.gov (United States)

P, DREWS; H, NIEMANN; J, COSFELD; Y, GAO; J, GEIGER; O, GRULKE; M, HENKEL; D, HÖSCHEN; K, HOLLFELD; C, KILLER; A, KRÄMER-FLECKEN; Y, LIANG; S, LIU; D, NICOLAI; O, NEUBAUER; M, RACK; B, SCHWEER; G, SATHEESWARAN; L, RUDISCHHAUSER; N, SANDRI; N, WANG; the W7-X Team

2018-05-01

Controlling the heat and particle fluxes in the plasma edge and on the plasma facing components is important for the safe and effective operation of every magnetically confined fusion device. This was attempted on Wendelstein 7-X in the first operational campaign, with the modification of the magnetic configuration by use of the trim coils and tuning the field coil currents, commonly named iota scan. Ideally, the heat loads on the five limiters are equal. However, they differ between each limiter and are non-uniform, due to the (relatively small) error fields caused by the misalignment of components. It is therefore necessary to study the influence of the configuration changes on the transport of heat and particles in the plasma edge caused by the application of error fields and the change of the magnetic configuration. In this paper the up-stream measurements conducted with the combined probe are compared to the downstream measurements with the DIAS infrared camera on the limiter.

Low- and high-mode separation of short wavelength turbulence in dithering Wendelstein 7-AS plasmas

DEFF Research Database (Denmark)

Basse, N.P.; Zoletnik, S.; Saffman, M.

2002-01-01

In this article measurements of small scale electron density fluctuations in dithering high confinement (H)-mode plasmas obtained by collective scattering of infrared light are presented. A scan of the fluctuation wavenumber was made in a series of similar discharges in the Wendelstein 7-AS (W7-A...

Thermo-mechanical analysis of retro-reflectors for interferometry and polarimetry in W7-X

NARCIS (Netherlands)

Köppen, M.; Hirsch, M.; Ernst, J.; Vliegenthart, W.A.; Ye, M.Y.; Bykov, V.; Schauer, F.

2011-01-01

The stellarator Wendelstein 7-X (W7-X) is presently under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald, Germany. The plasma density profile will be measured by two-colour interferometry where for each line of sight through the plasma the phase shifts of two far-infrared

Turbulence at the transition to the high density H-mode in Wendelstein 7-AS plasmas

DEFF Research Database (Denmark)

Basse, N.P.; Zoletnik, S.; Baumel, S.

2003-01-01

Recently a new improved confinement regime was found in the Wendelstein 7-AS (W7-AS) stellarator (Renner H. et al 1989 Plasma Phys. Control. Fusion 31 1579). The discovery of this high density high confinement mode (HDH-mode) was facilitated by the installation of divertor modules. In this paper,...

Observation of MHD fluctuation by ECE on W7-X first experimental campaign

Science.gov (United States)

Tsuchiya, Hayato; Hirsch, Matthias; Weir, Gavin; Hofel, Udo; Beurskens, Marc; Masuzaki, Suguru; W7-X Team

2016-10-01

Wendelstein 7-X is an optimized stellarator for ECRH high density steady-state discharges at reactor relevant collisionality regimes. The first experiment (OP1.1) was successfully conducted from Dec.2015. ECE (Electron Cyclotron Emission diagnostic) is one of the main diagnostic during the first experimental campaign. The 2nd harmonic x-mode emission is obtained by outside-antenna and detected by 32-channel heterodyne radiometer. The frequency band is from 126GHz to 162GHz. Radiometers are calibrated by LN2 temperature and room temperature. The absolute calibration error was estimated to be 10%. The electron temperature radial profile obtained by ECE agrees the Thomson scattering and imaging X-ray spectroscopy result. The asymmetric profile is still indicated due to mix of O2-mode. Fluctuations derived from MHD instability are often observed by electron temperature and magnetic fluctuations. The radial mode structure is clearly identified by ECE. It indicates the existence of magnetic island and from its appearance on both sides of the X2 emission spectrum the knowledge on the localization of the ECE channels can be improved by symmetrization.

Power load limits of the WENDELSTEIN 7-X target elements-comparison of experimental results and design values for power loads up to the critical heat flux

International Nuclear Information System (INIS)

Greuner, H; Boeswirth, B; Boscary, J; Leuprecht, A; Plankensteiner, A

2007-01-01

The power load limits of the WENDELSTEIN7-X divertor target elements were experimentally evaluated with heat loads considerably exceeding the expected operating conditions. The water-cooled elements are designed for steady-state heat flux of 10 MW m -2 and to remove a power load up to 100 kW. The elements must allow a limited operation time at 12 MW m -2 steady-state and should not fail for short pulses of up to 15 MW m -2 for cooling conditions in the subcooled nucleate boiling regime. In the framework of the qualification phase, pre-series target elements were loaded up to 24 MW m -2 without loss of CFC tiles. A critical heat flux at the target of 31 MW m -2 was achieved. The paper discusses the results of the tests performed at the high heat flux test facility GLADIS. The experimental results compared to transient nonlinear fine element method (FEM) calculations confirm a high thermal safety margin of the target design sufficient for plasma operation in W7-X

Finite Element Based Design Optimization of WENDELSTEIN 7-X Divertor Targets

International Nuclear Information System (INIS)

Plankensteiner, A.; Leuprecht, A.; Schedler, B.; Scheiber, K.; Greuner, H.

2006-01-01

In the fusion experiment WENDELSTEIN 7-X divertor plasma facing components have to withstand severe loading conditions. In general thermally induced mechanical stressing turns out to be most critical with respect to life time predictions of the component. In the specific case flat tiles of CFC grade NB31 are joined to the precipitation hardened CuCrZr heat sink by employing an active metal cast (AMC)-Cu as an interlayer between CFC and CuCrZr. Residual stresses resulting from the manufacturing process act as initial stresses in the subsequent operational heat flux loading. For the latter loading regime these stresses intrinsically are generated due to the large contrast in the CTE for CFC and Cu. Different design variants of those CFC flat tile armoured target elements have been analysed via the finite element package ABAQUS aiming at derivation of an optimized component design. The numerical study comprises variants with different degrees of tessellation of the CFC flat tile section, orientation of the CFC, lamellar design of the AMC-interlayer, and different designs of the cooling channels. The thermo-mechanical material characteristics are accounted for the finite element models with elastic-plastic properties being assigned to the metallic sections CuCrZr and AMC-Cu, respectively, and orthotropic nonlinear-elastic properties being used to the CFC section. The latter has been realized in form of a user-defined material subroutine that is used at the integration point level of the finite element model. In particular, twelve scalar-type damage parameters obeying their own evolution equations with respect to the loading history account for specific stress-strain relationships in the three principal material directions and planes with six damage parameters being used for normal loading under tensile and compressive stress states, respectively, and six parameters being used for shear loading. For the aim of model verification calculated surface temperatures, global

Transition of W7-X non-planar coils from manufacturing to assembly

Energy Technology Data Exchange (ETDEWEB)

Ehrke, G. [Max-Planck-Institut fuer Plasmaphysik (IPP), EURATOM Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)], E-mail: gunnar.ehrke@ipp.mpg.de

2009-06-15

The main magnetic field of Wendelstein 7-X fusion experiment (W7-X) at Max-Planck-Institut fuer Plasmaphysik Greifswald, Germany will be provided by 50 non-planar coils and supported by 20 planar coils. The non-planar coils were delivered by a consortium (CON) consisting of Babcock Noell GmbH Germany (BNG) and ASG Superconductors S.p.A. Italy (ASG). The coil production ended with the delivery of the last non-planar coil in March 2008 at the manufacturing branch of BNG in Zeitz, Germany. The construction of the coils was characterised by design changes, many rework actions and resulting time delays. Due to these numerous adjustments and changes a continuous improvement process was needed. This paper will give an overview about the transition of the non-planar coils from the acceptance tests at the manufacturer site to the beginning of the assembly at IPP. Furthermore this report will highlight technical interfaces in the period of transition.

Designs of Langmuir probes for W7-X

International Nuclear Information System (INIS)

Laube, Ralph; Laux, Michael; Ye, Min You; Greuner, Henri; Lindig, Stefan

2011-01-01

Several designs of Langmuir probes for the stellarator Wendelstein 7-X (W7-X) are described. Different types of probes are proposed for the different divertors to be used during different operational phases of W7-X. Comb-like arrays of stiff probes, arrays of flexible probes, and fixed inlay probes are reviewed. For the initial phase of W7-X it was decided to install arrays of fixed inlay probes. Two mockups were manufactured and one of them was tested with success in the high heat flux test facility GLADIS. For long-pulse operation of W7-X different conceptual designs are proposed and are still developed further. This paper summarizes the different design constrains for the Langmuir probes in the different divertor surroundings, describes the design of the array of inlay probes for the initial phase and the result of the GLADIS test, and gives a preview of the conceptual designs of probes for the long-pulse operational phase of W7-X.

Magnetic surfaces and localized perturbations in the Wendelstein VII-A stellarator

International Nuclear Information System (INIS)

Wobig, H.

1986-09-01

The critical dependence of plasma confinement in low-shear stellarators, such as Wendelstein VII-A, on the external rotational transform can be explained on the basis of magnetic surface destruction. External symmetry-breaking perturbations generate islands on the low order rational magnetic surfaces. The islands are largest at t=1/2 and t=1/3. Confinement is optimum in close proximity to these values. In order to study the structure of surfaces under the influence of perturbations, a mapping procedure is used instead of field line integration. It is found that the neighbourhood of low- order rational surfaces is particularly robust against surface destruction. The reason is that in this vicinity only rational surfaces with large m and n exist (t=m/n). On these surfaces the external perturbation only generates small islands. In W VII-A the current leads to the helical windings are one symmetry- breaking perturbation, and there might also be others. It is possible to avoid field errors of this kind in future stellarators. (orig.)

Numerical study of the connection lengths for various magnetic configurations in Wendelstein 7-X to optimize the heat load on the divertor

Energy Technology Data Exchange (ETDEWEB)

Sinha, Priyanjana; Hoelbe, Hauke; Sunn Pedersen, Thomas [Max Planck Institute of Plasma Physics, Greifswald (Germany)

2016-07-01

Fusion has the potential to play an important role as a future energy resource. It has the capacity to produce large-scale clean energy. The two main confinement concepts are the tokamak and the stellarator. The W7-X machine is based on stellarator principle and is using special form of coils to achieve steady-state plasma confinement. Divertors are used in tokamaks and stellarator to control the exhaust of waste gases and impurities from the machine. The divertor concept of W7-X is a so-called island divertor. The island chain isolates the confinement core from regions where the plasma-wall interaction takes place. The area of the divertor that receives the main part of the heat loads, the so-called wetted area, increases with the distance along the magnetic field from the outboard midplane to the divertor target. The connection length is relatively short in tokamaks with conventional divertors. In the stellarator island divertor, the connection length can be varied significantly, which should allow for optimization of the wetted area. We present here a numerical study of the achievable connection lengths in various W7-X configurations and discuss the possibilities for running dedicated experiments to understand the physics of what sets the wetted area.

Investigation of fluctuations in the HDH and H* regime of Wendelstein 7-AS

International Nuclear Information System (INIS)

Baeumel, S.; Werner, A.; McCormick, K.

2003-01-01

The High Density H-Mode Regime was discovered in Island Divertor operation of the Wendelstein 7-AS (W7-AS)stellerator. This regime is characterized by low impurity, high-energy confinement times - up to twice the value of the International Stellarator Scaling ISS95 - and edge radiated power fractions of up to 90% in detached state. Regarding the enhanced impurity transport at good energy confinement there are similarities to the enhanced D α H-mode found on the Alcator C-Mod tokamak. In W7-AS studies were performed in order to compare the HDH regime with the classical ELM-free discharges (H * ). Although both regimes are similar in collisionality and have almost the same n e (r)- and T e (r)-profile shapes, the H * regime suffers a radiation collapse due to impurity accumulation. The short impurity confinement times in HDH discharges requires enhanced transport at the plasma edge. The cause is not clear and this contribution looks for similarities to the enhanced D α H-mode of Alcator C-Mod, that is, whether quasicoherent modes exist in W7-AS causing enhanced edge transport. Discharges with a variation of magnetic configurations, densities (up to 4.10 20 m -3 ) and powers (up to 3.2 MW absorbed) will be discussed with respect to the different behaviour of fluctuations. (orig.)

Assessment of the plasma start-up in Wendelstein 7-X with neutral beam injection

International Nuclear Information System (INIS)

Gradic, D.; Dinklage, A.; Brakel, R.; McNeely, P.; Rust, N.; Wolf, R.; Osakabe, M.

2015-01-01

Plasma start-up by neutral beam injection was investigated for stellarators. A zero-dimensional collisional model was extended to evaluate the temporal evolution of the plasma start-up in a confining toroidal magnetic field. Inclusion of different beam energy components indicated a substantial effect due to the energy dependence of beam–gas collisions. Additional collision processes and particle equations were considered to simulate the plasma start-up in helium–hydrogen mixtures. The isotope effect between operation with hydrogen and deuterium beams was also investigated. As a major objective the conditions necessary for a plasma start-up with neutral beams in W7-X have been examined. The assessed beam configuration in W7-X was found not to allow plasma start-up by neutral beam injection alone. The model has been validated for experimental data from W7-AS and Large Helical Device. Quantitative predictions of this study show that the ratio of the beam–plasma interaction length and the plasma volume is an essential quantity for the successful plasma start-up with neutral beams. (paper)

Overview and status of the system control of WENDELSTEIN 7-X

International Nuclear Information System (INIS)

Schacht, J.; Laqua, H.; Lewerentz, M.; Mueller, I.; Pingel, S.; Spring, A.; Woelk, A.

2006-01-01

The new quality of the superconducting fusion device W7-X is its capability for long-pulse operation. Discharge operations can be up to 30 minutes with full heating power. Considering the steady state operation capability the W7-X system control will be important for future long-term fusion experiments. A wide spectrum of requirements has to be considered during design and realization of the system control of W7-X. The experimental nature of the W7-X project requires high flexibility for machine operation and automatic program controlled operation. During the planned life cycle of about two decades the scientific programs will be permanently adapted to new aspects. New components will be included into the control system and established systems have to be adapted with respect to technological progress. The device W7-X is a very complex technical system. On the top of the hierarchically structured system control the central control system is located. Local components, e.g. power supplies, heating systems, and diagnostics, have their own control systems. For commissioning and tests local systems will be run autonomously. In preparation for experiment operation all essential components will be subordinated to the central control system. During experiments the central control system coordinates the activity of these components. A special segment control system is responsible for processing predefined programs. The configuration of a discharge phase can be set very flexible: Short pulses with arbitrary intervals, steady state long discharges and arbitrary sequences of short phases with different characteristics in one discharge will be supported by the segment control system. The interactive session leader program allows to choose and chain predefined segment programs, to start or stop a segment program chain as a discharge. The progress of the discharge is visualized by a sequence monitor. The independent safety system consists of local units responsible for the safety

Analysis of the accident with the coolant discharge into the plasma vessel of the W7-X fusion experimental facility

Energy Technology Data Exchange (ETDEWEB)

Ušpuras, E.; Kaliatka, A.; Kaliatka, T., E-mail: tadas@mail.lei.lt

2013-06-15

Highlights: • The accident with water ingress into the plasma vessel in Wendelstein nuclear fusion device W7-X was analyzed. • The analysis of the processes in the plasma vessel and ventilation system was performed using thermal-hydraulic RELAP5 Mod3.3 code. • The suitability of pressure increase prevention system was assessed. • All analyses results will be used for the optimization of W7-X design and to ensure safe operation of this nuclear fusion device. -- Abstract: Fusion is the energy production technology, which could potentially solve problems with growing energy demand of population in the future. Starting 2007, Lithuanian Energy Institute (LEI) is a member of European Fusion Development Agreement (EFDA) organization. LEI is cooperating with Max Planck Institute for Plasma Physics (IPP, Germany) in the frames of EFDA project by performing safety analysis of fusion device W7-X. Wendelstein 7-X (W7-X) is an experimental stellarator facility currently being built in Greifswald, Germany, which shall demonstrate that in the future energy could be produced in such type of fusion reactors. In this paper the safety analysis of 40 mm inner diameter coolant pipe rupture in cooling circuit and discharge of steam–water mixture through the leak into plasma vessel during the W7-X no-plasma “baking” operation mode is presented. For the analysis the model of W7-X cooling system (pumps, valves, pipes, hydro-accumulators, and heat exchangers) and plasma vessel was developed by employing system thermal-hydraulic state-of-the-art RELAP5 Mod3.3 code. This paper demonstrated that the developed RELAP5 model enables to analyze the processes in divertor cooling system and plasma vessel. The results of analysis demonstrated that the proposed burst disc, connecting the plasma vessel with venting system, opens and pressure inside plasma vessel does not exceed the limiting 1.1 × 10{sup 5} Pa absolute pressure. Thus, the plasma vessel remains intact after loss

Design principles for handmade electrical insulation of superconducting joints in W7-X

Energy Technology Data Exchange (ETDEWEB)

Rummel, K., E-mail: kerstin.rummel@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); John, A. [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Sulek, Z. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Radzikowskiego 152 (Poland)

2013-10-15

Highlights: ► In W-7X there are several types of handmade electrical insulation. ► In general insulation based on impregnated glass tapes and special G10 pieces. ► A proper overlapping of glass tapes turned out to be mandatory. ► Detailed qualification and training helps to minimize the failure rate. ► Visual inspection and Paschen tests after every insulation steps are important. -- Abstract: The superconducting magnet system of the Wendelstein 7-X (W7-X) experiment consists of 50 non-planar and 20 planar coils, 121 bus bars and 14 current leads. The connection between bus bars, coils and current leads will be provided by 198 joints. The joints have to be insulated manually during the assembly of the machine in constraint positions and a tight environment. In general the insulation is based on glass tapes impregnated with epoxy resin and special G10 insulating pieces embedded in the glass tape insulation. In critical areas Kapton{sup ®}-foils are embedded in the insulation. All types of insulation were qualified at mock-ups in a 1:1 model of the expected environment in W7-X. The qualification programme comprises thermal cycling between room temperature and 77 K and high voltage tests under air, under vacuum and under reduced pressure (Paschen test). The paper describes the main principles used for different types of handmade Paschen-tight insulations in W7-X and the visual and electrical tests during and after assembly.

Shielding of the NBI boxes against W7-X magnetic stray fields

Energy Technology Data Exchange (ETDEWEB)

Kick, Manfred [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)], E-mail: Kick@arcor.de; Sielanko, Juliusz [Maria Curie Sklodowska University, Pl. M. C. Sklodowskie 1, 20-031 Lublin (Poland); Heinemann, Bernd; Riedl, Rudolf; Speth, Eckehart; Staebler, Albrecht [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748 Garching (Germany)

2009-06-15

Neutral Beam Injection (NBI), besides ECRH, is foreseen as one of the main heating devices at the W7-X stellarator currently under construction at IPP Greifswald, Germany. In a final stage 20 MW of NBI heating power will be installed generated by two NBI boxes of the ASDEX Upgrade (AUG) type. Since magnetic fields generally affect the trajectories of charged particles, essentially all the NBI boxes - including ion sources, acceleration sections, neutralisers and deflection magnets - must be shielded against the stray fields of W7-X. In the magnetic stray fields of W7-X there exist significant radial and toroidal components whereas at tokamaks the vertical components are dominant. The power loads on the ion dump and the protecting structures of the deflecting magnets and the beam lines caused by residual beam ions, therefore, will be strongly different. Thus the shielding concept of AUG cannot simply be taken over, but must be carefully redesigned in order to remain below the critical power limits. New modelling calculations of the magnetic shielding, the ion trajectories and the resulting power loads have been carried out for the 'high iota' and 'low shear' experimental scenarios of W7-X. The fields taken for these calculations are modelled by averaging the calculated W7-X stray fields on the one hand, and by fields generated by two-hypothetical-planar coils perpendicular to the x-y plane, on the other hand. The shielding concept for W7-X mainly consist of iron plates in the outer side regions of the boxes and as little magnetic material as possible inside the boxes.

Density, potential and temperature fluctuations in Wendelstein 7-AS and ASDEX

International Nuclear Information System (INIS)

Balbin, R.; Hidalgo, C.; Carlson, A.; Endler, M.; Giannone, L.; Herre, G.; Niedermeyer, H.; Rudyj, A.; Theimer, G.

1992-01-01

Measurements of ion saturation current, floating potential and temperature fluctuations in Wendelstein 7-AS stellarator (W7-AS) and ASDEX tokamak have been carried out. A reciprocating Langmuir probe with an array of 19 graphite tips has been used to obtain the radial profiles of these fluctuations in W7-AS and ASDEX. In both devices, a reversal of the radial electric field and an associated velocity shear layer at the plasma boundary have been observed. At the radial position where the phase velocity the poloidal direction of the fluctuations goes to zero, the normalised ion saturation current fluctuation level of 0.2 is the same for edge plasma parameters of similar temperatures and densities. A spatial crosscorrelation between floating potential and ion saturation current fluctuations has been observed in both machines and this feature can be explained in terms of turbulent eddies. A comparison of fluctuations in a tokamak and stellarator therefore shows many features in common. (orig.)

MIB Probes for measurements of particle and energy fluxes in plasma of Wendelstein 7-X

Science.gov (United States)

Demidov, V. I.; Koepke, M. E.; Kurlyandskaya, I. P.; Raitses, Y.

2014-10-01

Magnetically insulated baffled (MIB) probes and probe arrays that share the simplicity of simple Langmuir probes but supersede them in their ability to make real-time measurements of plasma potential, temperature and energy/particle fluxes in W7-X stellarator plasma are being developed. The probes offer the advantages of direct measurements of the plasma fluid observables, while being non-emitting and electrically floating. The principle of operation of the probe is based on the dependence of the voltage drop in the plasma-probe sheath on the direction of the local magnetic field. The core technology for these probes rests with the use of a special baffling configuration such that electron current to the probe is fully controllable in the closed, open or partially open orientation, by a simple rotation of the baffle with respect to the magnetic field alignment in the plasma. The baffled-probe designs proposed for edge diagnostics will increase the capability to characterize separately plasma properties in real-time for understanding of underlying physics in the edge plasma.

High heat flux tests of the WENDELSTEIN 7-X pre-series target elements - experimental evaluation of the thermo-mechanical behaviour

International Nuclear Information System (INIS)

Greuner, H.; Boeswirth, B.; Boscary, J.; Plankensteiner, A.; Schedler, B.

2006-01-01

The HHF testing of WENDELSTEIN 7-X pre-series target elements is an indispensable step in the qualification of the manufacturing process. The finally 890 divertor target elements are made of an actively water-cooled CuCrZr heat sink covered with flat tiles of CFC NB31 as plasma facing material. A set of 20 full scale pre-series elements was manufactured by PLANSEE to validate the materials and manufacturing technologies prior to the start of the series production. Due to the large mismatch in the coefficients of thermal expansion for CFC and CuCrZr - resulting in high residual stresses as well as high operation-induced stresses - the bonding zone between CFC and CuCrZr was detected to be the most critical issue for the operational behaviour of the target elements. To achieve a sufficiently high manufacturing quality together with a high lifetime during operation thermal testing of full scale mockups was performed in combination with extensive FEM analyses. In both cases heat loads were applied similar to the expected heat loads in W7-X. All pre-series elements were tested in the ion beam test facility GLADIS. The elements were tested with 100 cycles of 10 MW/m 2 and several elements with even higher cycle numbers and heat loads up to 24 MW/m 2 . The instrumentation of the targets (thermocouples, strain gages) and the infrared camera observation of the heat loaded surface allow an experimental evaluation of the thermo-mechanical behaviour of the tested elements. The main result is a good agreement between experimental data and numerically computed predictions. Hot spots were, however, observed at the edges of several tiles during the HHF tests indicating local bonding problems. Therefore, a programme of fully 3D nonlinear thermal-mechanical FEM calculations was started to evaluate the thermo-mechanical behavior of the target elements with special focus on the optimization of the stress situation in the bonding zone between the CFC and the CuCrZr heat sink. This

Turn-key supply for the power supplies of the control coils of wendelstein 7-X experiment

International Nuclear Information System (INIS)

Jauregi, E.; Ganuza, D.; Garcia, I.; Rio, J.M. del; Rummel, T.; Fuellenbach, F.

2003-01-01

In the Max-Planck Institute for Plasma Physics, IPP, in Greifswald, a new stellerator is being built for fusion research experiments, the so called Wendelstein 7-X Experiment. JEMA Company has designed, manufacture and supply the turnkey system which energises the ten control coils in the stellerator. The system comprises ten independent Switch-mode power supplies, and the central distribution stations for power, cooling and control facilities. Each power supply must provide a controlled current compounded of direct current and 0-20 Hz bandwidth ac current in a range of almost 3 kA at low voltage, 30 V, in four quadrants. Positive and negative voltage and sinusoidal current with low harmonic distortion is required by load. The selected design is based on Switch-mode-power supply technology (SMPS) providing the system with a very high regulation response (very low current and voltage ripple) and excellent input power factor, keeping the grid total harmonic distortion (THD) under minimum values. The sources can be operated locally as independent systems or they can be co-ordinated from a main control keeping current synchronisation requirements. The system in its entirety requires a high efficiency due to thermal considerations and reduced space. The system presented here introduces a decisive solution for the future power supplies to superconducting or regular coils, where the regulation, precision and ripple are the basic requirements for the design. During year 2000 the design stage was covered and in 2001 a first prototype for the power supplies was manufactured and successfully tested at factory. The entire system has been installed over this year after the series fabrication and it is currently working at IPP facilities, waiting for the acceptance tests scheduled before end of the year. This paper aims to explain the different stages the company went through in order to get validation of the power supply system and make it running at its last location

Density, potential and temperature fluctuations in Wendelstein 7-AS and ASDEX

Energy Technology Data Exchange (ETDEWEB)

Balbin, R; Hidalgo, C [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Carlson, A; Endler, M; Giannone, L.; Niedermeyer, H; Rudyj, A; Theimer, G [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

1993-12-31

Measurements of density, potential and temperature fluctuations in Wendelstein 7-AS stellarator (W7-AS) and ASDEX tokamak have been carried out. The properties of plasma fluctuations in a tokamak and stellarator can then be compared. A reciprocating Langmuir probe with an array of 19 graphite tips has been used to measure the radial profiles of fluctuations in the ion saturation current and floating potential in W7-AS and ASDEX. In both devices, a reversal in radial electric field and an associated velocity shear layer at the plasma boundary have been observed and in both cases the normalized ion saturation current fluctuation level decreases monotonically moving towards the plasma centre and through the shear layer. At the radial position where the phase velocity in the poloidal direction of the fluctuations goes to zero, the normalized ion saturation current fluctuation level of 0.25 are similar for edge plasma parameters of similar temperatures and densities. A spatial crosscorrelation between fluctuations in floating potential and ion saturation current has been observed in both machines. (author) 6 refs., 4 figs.

Magnetic-entropy change in Mn1.1Fe0.9P0.7As0.3-xGe x

International Nuclear Information System (INIS)

Tegus, O.; Fuquan, B.; Dagula, W.; Zhang, L.; Brueck, E.; Si, P.Z.; Boer, F.R. de; Buschow, K.H.J.

2005-01-01

We have studied the magnetic properties and magnetic-entropy changes of Mn 1.1 Fe 0.9 P 0.7 As 0.3-x Ge x compounds with x = 0, 0.05, 0.1, 0.15 and 0.3. X-ray diffraction (XRD) study shows all the compounds crystallize in the Fe 2 P-type structure. Magnetic measurements show that the Curie temperature increases from 150 K for Mn 1.1 Fe 0.9 P 0.7 As 0.3 to 380 K for Mn 1.1 Fe 0.9 P 0.7 Ge 0.3 . A field-induced first-order magnetic phase transition is observed above the Curie temperature for the compounds with x up to 0.15. There exists an optimal composition in which the first-order phase transition is the sharpest. The optimal composition for this system is x = 0.1. The maximal magnetic-entropy change derived from the magnetization data is about 40 J/(kg K) for a field change from 0 to 3 T

Remarks on application of VMEC and PROCTR to the Wendelstein 7-AS experiment

International Nuclear Information System (INIS)

Yamada, H.; Geiger, J.; Stroth, U.; Weller, A.; Howe, H.C.

1994-02-01

This report describes the application of the VMEC (Variational Moments Equilibrium Code) and PROCTR (PRedictOr Corrector TRansport code) numerical codes to the W7-AS experiment. The different versions of VMEC, each of which has been used for W7-AS and CHS (National Institute for Fusion Science, Nagoya, Japan), were compared to confirm their reliability and performance, and successfully benchmarked. The PROCTR code set was installed in the Wendelstein-VAX cluster. Its potential in experimental interpretation and theoretical analysis was demonstrated for coordinate inversion based on full 3-D geometry, power balance analysis and time-dependent transport simulation. The benchmark tests of tools for finite-β equilibrium and power balance analysis are a prerequisite for the joint profile and configuration database for stellarators which has just been started. We successfully recognized the compatibility of the schemes used on W7-AS and CHS. (orig.)

Bulk-boronized limiter operation in the Wendelstein 7-AS stellarator

Energy Technology Data Exchange (ETDEWEB)

Brakel, R; Burhenn, R; Behrisch, R; Grigull, P; Hacker, H; Hildebrandt, D; Hofmann, J V; Mahn, C; Roth, J; Schneider, U; Weller, A [Max-Planck-Inst. fuer Plasmaphysik, Garching (Germany); Hirooka, Y [Inst. of Plasma Physics and Fusion Research, Univ. California, Los Angeles, CA (United States); W7-AS Team; NI Group; ECRH Group

1992-12-01

Bulk-boronized graphite (20% boron) has been tested as a limiter material in the Wendelstein 7-AS stellarator. The recycling behaviour and the plasma impurities are compared for the new material and the formerly used TiC-coated graphite with stainless steel and boronized walls. After conditioning the recycling and the oxygen and carbon levels are comparable for both materials. No significant impact of sputter boronization from the limiters on the oxygen level was observed. A drastical reduction of oxygen by about a factor of 10 was obtained only after additional gas boronization. In this case Z[sub eff] is primarily determined by carbon and boron. For ECF standard discharges Z[sub eff][approx equal]2 with P[sub rad]=6% of the input power was found as compared to Z[sub eff]< or approx.3 and P[sub rad]=10% before boronization and Z[sub eff][approx equal]4, P[sub rad]=20% with TiC-limiters. (orig.).

Effects of toroidal currents upon magnetic configurations and stability in Wendelstein 7-AS

International Nuclear Information System (INIS)

Weller, A.; Anton, M.; Brakel, R.; Geiger, J.; Hirsch, M.; Jaenicke, R.; Klose, S.; Werner, A.; Sallander, E.

2001-01-01

The proposal of new concepts for current carrying hybrid stellarators has raised the issue if current driven instabilities, in particular major disruptions, may be suppressed or mitigated by the externally provided poloidal magnetic field. In W7-AS the internal toroidal currents such as bootstrap and Okhawa currents are cancelled by opposite currents driven inductively or by electron cyclotron current drive (ECCD). In this way the edge rotational transform is controlled, and net current-free stable plasmas are maintained. On the other hand, the current drive systems provide a flexible tool to investigate current driven instabilities as well as various issues concerning the effect of magnetic shear on confinement and MHD mode behaviour. The stability studies in the presence of significant toroidal currents have been made in the accessible range of the external rotational transform slash-l ext =0.30...0.56 involving the low order rational surfaces slash-l = 1/2, 3/2, 3/4 and 1. In addition the rational surfaces slash-l=1/3 and 1/4 could be accessed by reverse current drive. Target plasmas heated by electron cyclotron resonance heating (ECRH), neutral beam injection (NBI) or both were investigated in order to assess to which extent the stability depends on particular current density profiles. Disruption-like events, preceded by tearing mode activity, have been observed in a wide range of the external rotational transform. The mode structures have been analyzed by X-ray tomography, electron cyclotron emission (ECE) diagnostics and magnetic measurements. The experimental data are roughly consistent with stability calculations on the basis of a cylindrical Δ'-analysis. In contrast to the tokamak case the plasma equilibrium is maintained even after a thermal collapse enabling a recovery of plasma energy and inductive current. The improved positional stability can result in the formation of very large magnetic islands. Severe disruption-like effects may be controlled by

Upgraded acceptance criteria from transient thermography control for the W7-X divertor target elements

Energy Technology Data Exchange (ETDEWEB)

Missirlian, M. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France)], E-mail: marc.missirlian@cea.fr; Boscary, J. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching (Germany); Guigon, R.; Schlosser, J.; Durocher, A. [CEA, IRFM, F-13108 Saint-Paul-Lez-Durance (France); Greuner, H. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching (Germany)

2009-06-15

The commissioning of plasma-facing component fields needs advanced non-destructive methods to detect in a reliable way the defects, which can impair the component performances and/or integrity during operation. Within this framework, CEA developed a dedicated non-destructive examination method based on active infrared thermography (SATIR facility) to inspect the bonding between armour material and metallic heat sink. Used with successful in the commissioning of the toroidal pump limiter of Tore Supra, this technique was applied in the frame of the pre-series activities of the Wendelstein 7-X high heat flux divertor elements to assess the bonding quality of the delivered components. This paper presents the methodology adopted to define an acceptance criterion based on SATIR test bed possibly applied for a serial inspection of the Wendelstein 7-X elements. Using the well-tried acceptance test based on the DTref{sub m}ax parameter, the new method includes advanced data post-processing techniques from thermo-signal SATIR and a data merging method to help the decision-making and to optimise the reliability of the binary response expected for a final decision in terms of acceptance test.

Upgraded acceptance criteria from transient thermography control for the W7-X divertor target elements

International Nuclear Information System (INIS)

Missirlian, M.; Boscary, J.; Guigon, R.; Schlosser, J.; Durocher, A.; Greuner, H.

2009-01-01

The commissioning of plasma-facing component fields needs advanced non-destructive methods to detect in a reliable way the defects, which can impair the component performances and/or integrity during operation. Within this framework, CEA developed a dedicated non-destructive examination method based on active infrared thermography (SATIR facility) to inspect the bonding between armour material and metallic heat sink. Used with successful in the commissioning of the toroidal pump limiter of Tore Supra, this technique was applied in the frame of the pre-series activities of the Wendelstein 7-X high heat flux divertor elements to assess the bonding quality of the delivered components. This paper presents the methodology adopted to define an acceptance criterion based on SATIR test bed possibly applied for a serial inspection of the Wendelstein 7-X elements. Using the well-tried acceptance test based on the DTref m ax parameter, the new method includes advanced data post-processing techniques from thermo-signal SATIR and a data merging method to help the decision-making and to optimise the reliability of the binary response expected for a final decision in terms of acceptance test.

A universal portable appliance for stellarator W7-X power supply controlling

International Nuclear Information System (INIS)

Xu Weihua

2001-01-01

In the project Wendelstein 7-X (W7-X), the popular field bus Profibus has been determined as a uniform connection between the central control system and all the subordinate systems. A universal embedded control system has been developed for W7-X power supply controlling. Siemens 80C167CR micro-controller is used as the central control unit of the system. With a user-defined printed circuit board (PCB) several control buses, i.e., Profibus, CAN, IEEE 488, RS485 and RS232 have been connected to the micro-controller. The corresponding hardware interfaces for the control buses have been designed. A graphic liquid crystal display (LCD) and a user-defined keyboard are used as user interface. The control software will be developed with a C-like language, i.e., C166 for the controller

Modification of the turbulence in the plasma boundary of the Wendelstein 7-AS stellarator using electric probes

International Nuclear Information System (INIS)

Thomsen, H.; Endler, M.; Schubert, M.

2001-01-01

The fluctuations in the edge plasmas of magnetic fusion experiments are thought to play an important role in terms of anomalous energy and particle transport. Experiments on Wendelstein 7-AS were conducted with the primary goal to investigate the performance of influencing and modifying the turbulence in the plasma boundary using electrical probes. Two movable poloidal probe arrays were used for the experiments, one located on the inboard side of the vessel and the other on the outboard side. A subset of probe tips was used for actively driving the plasma by different control signals, the remaining probes collected fluctuation data in the plasma boundary. Poloidally, we find a significant cross-correlation between active and passive probes. From analysis of the coherency and phases of the passive probe tips, it can clearly be seen that the background ExB-rotation of the plasma plays a crucial role for the applied signals. In the case of externally driven waves by several phase-locked active probes, the direction of the wave propagation with respect to the plasma rotation (co- or counter-rotating) is essential for a proper coupling to the turbulence. In toroidal direction we find that the propagation of the signals along the magnetic field lines depends on co- or counter-rotation with respect to the background plasma rotation. (author)

Structural and magnetic investigations of CaBaCo{sub 4−x}Fe{sub x}O{sub 7} solid solutions

Energy Technology Data Exchange (ETDEWEB)

Turkin, D.I., E-mail: turkin@ihim.uran.ru [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg GSP-145, 620990 (Russian Federation); Bazuev, G.V. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, Ekaterinburg GSP-145, 620990 (Russian Federation); Korolev, A.V. [Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, 620041 Ekaterinburg GSP-145, 620999 (Russian Federation)

2017-01-15

Solid solutions of CaBaCo{sub 4−x}Fe{sub x}O{sub 7} (x=0, 0.05, 0.2, 1, 2) were synthesized by glycine-nitrate combustion process. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. In the examined range of the solid solutions, their crystal lattice symmetry changes from orthorhombic with space group Pbn2{sub 1} (0<x<0.5) to hexagonal with space group P6{sub 3}mc (x>0.5). The magnetic measurements revealed that even small doping (x=0.05) of the transition metal sublattice noticeably suppresses ferrimagnetism of the parent compound and induces an AF transition at 88 K. An increase in the doping concentration lowers the frustration parameter |θ{sub CW}|/T{sub C} from 17.2 (for x=0.05) to 13.7 (for x=2) and strengthens the antiferromagnetic interactions, which manifests itself in the Curie–Weiss temperature (θ{sub CW}) growth. The samples with x=0.05 and x=0.2 also show an additional magnetic transition at temperatures T{sub g} (55 and 70 K respectively). The temperature irreversibility between the ZFC and FC magnetization curves may suggest the formation of a spin-glass state below that temperature. - Highlights: • CaBaCo{sub 4−x}Fe{sub x}O{sub 7} solid solutions were synthesized by glycine-nitrate process. • At x=1 symmetry became hexagonal instead orthorhombic. • Fe-doping abruptly suppresses ferrimagnetism of CaBaCo{sub 4}O{sub 7}. • Increase of x is followed by enhancing of antiferromagnetic interactions.

Overview and status of the prototype project for Wendelstein 7-X control system

Energy Technology Data Exchange (ETDEWEB)

Schacht, Joerg [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)], E-mail: joerg.schacht@ipp.mpg.de; Bluhm, Torsten; Herbst, Uwe; Hennig, Christine; Heinrich, Stefan; Kuehner, Georg; Koester, Erik; Laqua, Heike; Lewerentz, Marc; Marquardt, Mirco; Meyer, Christiane; Mueller, Ina; Pingel, Steffen; Sachtleben, Juergen; Spring, Anett; Werner, Andreas; Woelk, Andreas [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)

2009-06-15

This contribution gives an overview of the project 'Prototype W7-X control system'. The objective of this prototype project is to demonstrate the applicability of the segment orientated control system at a running fusion experiment including steady-state operation, interaction of all relevant components, real time control, data acquisition and on-line data analysis. Furthermore, the W7-X safety concept will be implemented at WEGA and tested.

The application of leak before break concept to W7-X target module

Energy Technology Data Exchange (ETDEWEB)

Dundulis, G., E-mail: gintas@mail.lei.lt; Janulionis, R.; Karalevičius, R.

2013-11-15

Highlights: • LBB application to Wendelstein 7-X fusion reactor. • R6 method application to crack analysis. • Through wall crack opening analysis. • Determination of leak rate function. • Crack growth analysis. -- Abstract: Fusion is the energy production technology, which could potentially solve problems with growing energy demand of population in the future. Wendelstein 7-X (W7-X) is an experimental stellarator of the helias type fusion reactor currently being built in Greifswald, Germany. This experimental stellarator is a complex structure, such as nuclear power plants and high level of safety requirements should be used for structural integrity analysis. It is thus not possible to obtain simple solutions for general cases, therefore sophisticated methods are necessary for the analysis. Inside the Plasma Vessel (PV) of W7-X there is a number of different components such as pipes, divertors, baffles and targets. A guillotine failure of one component is very dangerous for structural integrity of surrounding components located in PV. For this reason it is very important to evaluate possibility to apply “leak before break” (LBB) concept for W7-X. The LBB concept is widely used in the nuclear industry to describe the idea that in the piping carrying the coolant of a power reactor a leak will occur before a catastrophic break will occurred. LBB allows to conduct the structural design without considering the loads due to postulated line breaks. The LBB analysis was made for the case when plasma vessel is operating in “baking” mode. “Baking” is the mode, when the cooling system is working as a warming system and it heats the plasma vessel structures up to 160 °C in order to release the absorbed gases from the surfaces and to pump them out of the plasma vessel before plasma operation. The LBB analysis was performed for most loaded component of target module. According to the results of the analysis it is possible to conclude that target module 1H

Impurity transport in the Wendelstein VII-A stellarator

International Nuclear Information System (INIS)

1985-01-01

Impurity radiation losses in net-current-free neutral-beam-heated plasmas in the Wendelstein W VII-A stellarator are the combined effect of particularly strong impurity sources and improved particle confinement as compared with ohmically heated tokamak-like plasma discharges. Experiments are described and conclusions are drawn about the impurity species, their origin and their transport behaviour. The impurity transport is modelled by a 1-D impurity transport and radiation code. The evolution of the total radiation in time and space deduced from soft-X-ray and bolometer measurements can be fairly well simulated by the code. Experimentally, oxygen was found to make the main contribution to the radiation losses. In the calculations, an influx of cold oxygen desorbed from the walls of the order of 10 13 -10 14 cm -2 .s -1 and a rate of fast injected oxygen corresponding to a 1% impurity content of the neutral beams in combination with neoclassical impurity transport leads to quantitative agreement between the simulation and the observed radiation. The transport of A1 trace impurities injected by the laser blow-off technique was experimentally studied by soft-X-ray measurements using a differential method allowing extraction of the time evolution of A1 XII, XIII radial profiles. These are compared with code predictions, together with additional spectroscopic measurements. The main features of the impurity transport are consistent with neoclassical predictions, which explain particularly the central impurity accumulation. Some details, however, seem to require additional 'anomalous' transport. Such an enhancement is correlated with distortions of the magnetic configuration around resonant magnetic surfaces. (author)

Magnetic and magnetocaloric properties in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} exhibiting first-order and second-order magnetic phase transitions

Energy Technology Data Exchange (ETDEWEB)

Ho, T.A. [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Dang, N.T. [Institute of Research and Development, Duy Tan University, Da Nang (Viet Nam); Phan, The-Long [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Yang, D.S. [Physics Division, School of Science Education, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Lee, B.W. [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 449-791 (Korea, Republic of); Yu, S.C., E-mail: scyu@chungbuk.ac.kr [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

2016-08-15

Polycrystalline orthorhombic samples La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} (x = 0–0.09) were prepared by solid-state reaction. The study of magnetic properties revealed that the ferromagnetic-paramagnetic (FM-PM) transition temperature (T{sub C}) increases from 255 to about 271 K with increasing Na-doping content (x) from 0 to 0.09, respectively. Around the T{sub C}, we have found the samples showing a large magnetocaloric (MC) effect with maximum values of magnetic entropy change (|ΔS{sub max}|) of 7–8 J kg{sup −1} K{sup −1} and relative cooling power RCP = 232–236 J/kg for the samples x = 0.03–0.09 in a magnetic-field interval ΔH = 40 kOe. Detailed analyses of isothermal magnetization data M(T, H) based on Banerjee's criteria indicated a first-to-second-order magnetic-phase transformation taking place at a threshold Na-doping concentration x{sub c} ≈ 0.06. This could also be observed clearly from the feature of entropy universal curves. An assessment of the magnetic-ordering exponent N = dLn|ΔS{sub m}|/dLnH demonstrates an existence of short-range magnetic order in the samples. We believe that the changes of the magnetic properties and MC effect in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3} caused by Na doping are related to the changes in the structural parameters and Mn{sup 4+}/Mn{sup 3+} ratio, which are confirmed by the geometrical and electronic analyses based on X-ray diffraction and X-ray absorption fine structure. - Highlights: • Geometrical and electronic structures of La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3}. • Threshold of first-to-second-order phase transformation in La{sub 0.7}Ca{sub 0.3−x}Na{sub x}MnO{sub 3}. • Large magneto-caloric effect with |ΔS{sub max}| ≈ 7–8 J kg{sup −1} K{sup −1}, and RCP = 232–236 J/kg. • Universal curve of magnetic-entropy change.

Magnetic study of superconductivity in YBa2Cu3O7-x thin films

International Nuclear Information System (INIS)

McGuire, T.R.; Gupta, A.; Koren, G.; Laibowitz, R.B.; Dimos, D.

1989-01-01

Magnetic and transport measurements on 0.3 micron thick films of YBa 2 Cu 3 O 7 - x made by a laser ablation technique show critical current densities of up to 40X10 6 amps/cm 2 . At 77K the transport data gives J c ∼5x10 6 amps/cm 2 while magnetic data is 40 % lower. Comparison is made with evaporated films

Self-generated magnetic flux in YBa$_2$Cu$_3$O$_{7-x}$ grain boundaries

OpenAIRE

Mints, R. G.; Papiashvili, Ilya

2000-01-01

Grain boundaries in YBa$_2$Cu$_3$O$_{7-x}$ superconducting films are considered as Josephson junctions with a critical current density $j_c(x)$ alternating along the junction. A self-generated magnetic flux is treated both analytically and numerically for an almost periodic distribution of $j_c(x)$. We obtained a magnetic flux-pattern similar to the one which was recently observed experimentally.

Magnetic and magnetocaloric properties of La{sub 1.4-x}Yb{sub x}Ca{sub 1.6}Mn{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Himcinschi, C. [Babes-Bolyai Univ., Cluj-Napoca (Romania). Faculty of Physics; GSI, Strasbourg (France). Inst. de Physique et Chemie des Materiaux; Burzo, E. [Babes-Bolyai Univ., Cluj-Napoca (Romania). Faculty of Physics; Deville, J.P. [GSI, Strasbourg (France). Inst. de Physique et Chemie des Materiaux

2001-07-01

Magnetic and magnetocaloric properties of La{sub 1.4-x}Yb{sub x}Ca{sub 1.6}Mn{sub 2}O{sub 7} system were studied. Polycrystalline samples with x = 0 and 0.2 were prepared by solid state reaction. Magnetic measurements show that Curie temperatures decrease from 246 K for x = 0 down to 211 K for x = 0.2. The temperature dependences of the magnetic entropy change {delta}S{sub M}, show peaks close to the magnetic transition temperatures. Peak values of {delta}S{sub M} = 2.7 J/kg K and 2.1 J/kg K were obtained for compositions x = 0 and 0.2. The decrease in {delta}S{sub M} when changing composition was correlated with the diminution of exchange interactions. (orig.)

Neutron diffraction and magnetic study of the Nd0.7Pb0.3Mn1-xFexO3 (0=<x=<0.1) perovskites

International Nuclear Information System (INIS)

Blanco, J.J.; Insausti, M.; Gil de Muro, I.; Lezama, L.; Rojo, T.

2006-01-01

The effect of Fe doping on the ferromagnetic Nd 0.7 Pb 0.3 Mn 1-x Fe x O 3 (x=0, 0.025, 0.05, 0.075, 0.1) phases has been studied in order to analyze the double-exchange interaction. The structural and magnetic study has been carried out by neutron powder diffraction and susceptibility measurements between 1.7 and 300K. The substitution of Fe at the Mn site results in reductions in both the Curie temperature T c and the magnetic moment per Mn ion without appreciable differences in the crystal structures. All the compounds crystallize in Pnma space group. The thermal evolution of the lattice parameters of the Nd 0.7 Pb 0.3 Mn 1-x Fe x O 3 (x=0.025, 0.05, 0.075) compounds shows discontinuities in volume and lattice parameters close to the magnetic transition temperature. Increasing amounts of Fe 3+ reduces the double exchange interactions and no magnetic contribution for x=0.1 is observed. The magnetic structures of Nd 0.7 Pb 0.3 Mn 1-x Fe x O 3 (x=0, 0.025, 0.05, 0.075) compounds show that the Nd and Mn ions are ferromagnetically ordered

Integrated assessment of thermal hydraulic processes in W7-X fusion experimental facility

Energy Technology Data Exchange (ETDEWEB)

Kaliatka, T., E-mail: tadas.kaliatka@lei.lt; Uspuras, E.; Kaliatka, A.

2017-02-15

Highlights: • The model of Ingress of Coolant Event experiment facility was developed using the RELAP5 code. • Calculation results were compared with Ingress of Coolant Event experiment data. • Using gained experience, the numerical model of Wendelstein 7-X facility was developed. • Performed analysis approved pressure increase protection system for LOCA event. - Abstract: Energy received from the nuclear fusion reaction is one of the most promising options for generating large amounts of carbon-free energy in the future. However, physical and technical problems existing in this technology are complicated. Several experimental nuclear fusion devices around the world have already been constructed, and several are under construction. However, the processes in the cooling system of the in-vessel components, vacuum vessel and pressure increase protection system of nuclear fusion devices are not widely studied. The largest amount of radioactive materials is concentrated in the vacuum vessel of the fusion device. Vacuum vessel is designed for the vacuum conditions inside the vessel. Rupture of the in-vessel components of the cooling system pipe may lead to a sharp pressure increase and possible damage of the vacuum vessel. To prevent the overpressure, the pressure increase protection system should be designed and implemented. Therefore, systematic and detailed experimental and numerical studies, regarding the thermal-hydraulic processes in cooling system, vacuum vessel and pressure increase protection system, are important and relevant. In this article, the numerical investigation of thermal-hydraulic processes in cooling systems of in-vessel components, vacuum vessels and pressure increase protection system of fusion devices is presented. Using the experience gained from the modelling of “Ingress of Coolant Event” experimental facilities, the numerical model of Wendelstein 7-X (W7-X) experimental fusion device was developed. The integrated analysis of the

Pendulum support of the W7-X plasma vessel: Design, tests, manufacturing, assembly, critical aspects, status

Energy Technology Data Exchange (ETDEWEB)

Missal, B., E-mail: bernd.missal@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Leher, F.; Schiller, T. [MAN Diesel and Turbo SE, Werftstraße 17, 94469 Deggendorf (Germany); Friedrich, P. [Universität Rostock, FB Maschinenbau und Schiffstechnik, Albert-Einsteins-Straße 2, 18051 Rostock (Germany); Capriccioli, A. [ENEA Frascati, Fusion Technology Unit, Frascati (Italy)

2014-10-15

Highlights: • Plasma vessel support has to allow vertical adjustment and horizontal passive movement. • Planar sliding tables with PTFE do not fulfill all requirements. • Pendulums can fulfill all requirements. • Geometry and material of spherical bearings had to be optimized in calculations and tests. • Optimized pendulums were manufactured and assembled. - Abstract: The superconducting helical advanced stellarator Wendelstein 7-X (W7-X) is under construction at the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, Germany. The three dimensional shape of plasma will be generated by 50 non-planar magnetic coils. The plasma vessel geometry follows exactly this three dimensional shape of plasma. To ensure the superconductivity of coils a cryo vacuum has to be generated. Therefore the coils and their support structure are enclosed within the outer vessel. Plasma vessel, coil structures and outer vessel have to be supported separately. This paper will describe the vertical supports of plasma vessel which have to fulfill two special requirements, vertical adjustability and horizontal mobility. These two tasks will be carried out by plasma vessel supports (PVS) with hydraulic cylinders, special sliding tables during assembly and pendulum supports during operating phase. The paper will give an overview of design, calculation, tests, fabrication, assembly, critical aspects and status of PVS.

Design and assembly technology for the thermal insulation of the W7-X cryostat

Energy Technology Data Exchange (ETDEWEB)

Risse, K., E-mail: konrad.risse@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik (IPP), Euratom Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Nagel, M.; Pietsch, M.; Braatz, A. [Max-Planck-Institut fuer Plasmaphysik (IPP), Euratom Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Binni, A. [MAN Diesel and Turbo SE, Dpt. OSA, Werftstrasse 17, D-94469 Deggendorf (Germany); Posselt, H. [Linde AG Engineering Div., Dr.-Carl-von-Linde-Strasse 6-14, D-82049 Hoellriegelskreuth (Germany)

2011-10-15

The Max-Planck-Institut fuer Plasmaphysik in Greifswald is building up the stellarator fusion experiment Wendelstein 7-X (W7-X). To operate the superconducting magnet system the vacuum and the cold structures are protected by a thermal insulated cryostat. The plasma vessel forms the inner cryostat wall, the outer wall is realised by a thermal insulated outer vessel. In addition 254 thermal insulated ports are fed through the cryogenic vacuum to allow the access to the plasma vessel for heating systems, supply lines or plasma diagnostics. The thermal insulation is being manufactured and assembled by MAN Diesel and Turbo SE (Germany). It consists of a multi-layer insulation (MLI) made of aluminized Kapton with a silk like fibreglass spacer and a thermal shield covering the inner cryostat surfaces. The shield on the plasma vessel is made of fibreglass reinforced epoxy resin with integrated copper meshes. The outer vessel insulation is made of brass panels with an average size of 3.3 x 2.0 m{sup 2}. Cooling loops made of stainless steel are connected via copper strips to the brass panels. Especially the complex 3 D shape of the plasma vessel, the restricted space inside the cryostat and the consideration of the operational component movements influenced the design work heavily. The manufacturing and the assembly has to fulfil stringent geometrical tolerances e.g. for the outer vessel panels +3/-2 mm.

Design and assembly technology for the thermal insulation of the W7-X cryostat

International Nuclear Information System (INIS)

Risse, K.; Nagel, M.; Pietsch, M.; Braatz, A.; Binni, A.; Posselt, H.

2011-01-01

The Max-Planck-Institut fuer Plasmaphysik in Greifswald is building up the stellarator fusion experiment Wendelstein 7-X (W7-X). To operate the superconducting magnet system the vacuum and the cold structures are protected by a thermal insulated cryostat. The plasma vessel forms the inner cryostat wall, the outer wall is realised by a thermal insulated outer vessel. In addition 254 thermal insulated ports are fed through the cryogenic vacuum to allow the access to the plasma vessel for heating systems, supply lines or plasma diagnostics. The thermal insulation is being manufactured and assembled by MAN Diesel and Turbo SE (Germany). It consists of a multi-layer insulation (MLI) made of aluminized Kapton with a silk like fibreglass spacer and a thermal shield covering the inner cryostat surfaces. The shield on the plasma vessel is made of fibreglass reinforced epoxy resin with integrated copper meshes. The outer vessel insulation is made of brass panels with an average size of 3.3 x 2.0 m 2 . Cooling loops made of stainless steel are connected via copper strips to the brass panels. Especially the complex 3 D shape of the plasma vessel, the restricted space inside the cryostat and the consideration of the operational component movements influenced the design work heavily. The manufacturing and the assembly has to fulfil stringent geometrical tolerances e.g. for the outer vessel panels +3/-2 mm.

Final Test of the W7-X Control Coils Power Supply and its Integration into the Overall Control Environment

International Nuclear Information System (INIS)

Fuellenbach, F.; Rummel, T.; Pingel, S.; Laqua, H.; Mueller, I.; Jauregi, E.

2006-01-01

In order to be able to vary the magnetic configuration of WENDELSTEIN 7-X (W7-X) at the plasma edge and allow sweeping of the power across the divertor target plates 10 '' control coils '' are installed inside the plasma vessel behind the baffle plates of the divertor. The coils are made of a hollow copper profile with eight turns each. The dimensions of the coils are 2,05 m x 0,35 m x 0,35 m with a three dimensional shape to fit into the narrow space between the baffles and the wall of the plasma vessel. Each of the ten coils is supplied by independent power supplies each providing bi-directionally a direct current of 2500 A with high accuracy and low ripple. To allow sweeping the power deposition from the plasma across the target plates the power supplies provide an alternating current of up to 625 A with frequencies up to 20 Hz which is synchronised between the ten supplies in order to maintain the symmetry of the magnetic field. The total output current of a power supply is a superposition of a direct current and an alternating current, where both parts have to be independently adjustable. JEMA, Spain provided the complete set of power supplies which are based on 10 independent four-quadrant power supplies with a link rectifier and includes a cooling water unit, a dedicated distribution and a central control and visualization system. All ten power supply units and auxiliary systems have meanwhile been installed and finally tested at the W7-X site in Greifswald. The paper focuses on the results of the final tests and measures to integrate the power supply system to the overall control system including the central PLC and PC's for experiment control, data acquisition- and security systems. (author)

Technical progress report on Wendelstein VII-AS

International Nuclear Information System (INIS)

Sapper, J.

1985-01-01

The modification of the WENDELSTEIN experiment at Garching into an advanced version with modular design was approved in 1982, after a planning time of one and a half year. The essential components /1,2/ of the new WENDELSTEIN VII-AS device are: - A modular field system instead of a helix and TF-system, consisting of 45 nonplanar coils. - A modular vacuum vessel, adapted to the coil system. - An additional TF-system for t-variation, consisting of 10 plane coils. - A structure shell for the modular field coils so that the vessel is free of coil forces

Turbulence in Wendelstein 7-AS plasmas measured by collective light scattering

Energy Technology Data Exchange (ETDEWEB)

Basse, Nils Plesner

2002-08-01

This Ph.D. thesis contains theoretical and experimental work on plasma turbulence measurements using collective light scattering. The motivation for measuring turbulence in hot fusion plasmas is, along with the method used and results obtained, the subject of chapter 1. The theoretical part is divided into three chapters. Chapter 2 contains a full analytical derivation of the expected dependency of the detected signal on plasma parameters. Thereafter, spatial resolution of the measurements using different methods is treated in chapter 3. Finally, the spectral analysis tools used later in the thesis are described and illustrated in chapter 4. The experimental part is divided into four chapters. In chapter 5 transport concepts relevant to the thesis are outlined. Main parameters of the Wendelstein 7-AS (W7-AS) stellarator in which measurements were made are collected in chapter 6. The setup used to study fluctuations in the electron density of W7-AS plasmas is covered in chapter 7. This localised turbulence scattering (LOTUS) diagnostic is based on a CO{sub 2} laser radiating at a wavelength of 10.59 {mu}m. Fast, heterodyne, dual volume detection at variable wavenumbers between 14 and 62 cm{sup -1} is performed. The central chapter of the thesis, chapter 8, contains an analysis of the measured density fluctuations before, during and after several confinement transition types. The aim was to achieve a better understanding of the connection between turbulence and the confinement quality of the plasma. Conclusions and suggestions for further work are summarised in chapter 9. (au)

Turbulence in Wendelstein 7-AS plasmas measured by collective light scattering

International Nuclear Information System (INIS)

Basse, Nils Plesner

2002-08-01

This Ph.D. thesis contains theoretical and experimental work on plasma turbulence measurements using collective light scattering. The motivation for measuring turbulence in hot fusion plasmas is, along with the method used and results obtained, the subject of chapter 1. The theoretical part is divided into three chapters. Chapter 2 contains a full analytical derivation of the expected dependency of the detected signal on plasma parameters. Thereafter, spatial resolution of the measurements using different methods is treated in chapter 3. Finally, the spectral analysis tools used later in the thesis are described and illustrated in chapter 4. The experimental part is divided into four chapters. In chapter 5 transport concepts relevant to the thesis are outlined. Main parameters of the Wendelstein 7-AS (W7-AS) stellarator in which measurements were made are collected in chapter 6. The setup used to study fluctuations in the electron density of W7-AS plasmas is covered in chapter 7. This localised turbulence scattering (LOTUS) diagnostic is based on a CO 2 laser radiating at a wavelength of 10.59 μm. Fast, heterodyne, dual volume detection at variable wavenumbers between 14 and 62 cm -1 is performed. The central chapter of the thesis, chapter 8, contains an analysis of the measured density fluctuations before, during and after several confinement transition types. The aim was to achieve a better understanding of the connection between turbulence and the confinement quality of the plasma. Conclusions and suggestions for further work are summarised in chapter 9. (au)

Magnetic and magnetocaloric properties of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ho, T.A. [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of); Lim, S.H., E-mail: sangholim@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of); Tho, P.T.; Phan, T.L. [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 17035 (Korea, Republic of); Yu, S.C. [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of)

2017-03-15

The magnetic Mn{sup 3+} ions in La{sub 0.7}Ca{sub 0.3}MnO{sub 3} are partially replaced by nonmagnetic Zn{sup 2+} ions to form La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3} compounds (x=0.0, 0.06, 0.08, and 0.1), and their magnetic and magnetocaloric properties are investigated. The Curie temperature decreases drastically from 245 to 70 K as x increases from 0 to 0.1. An analysis using the Banerjee's criterion of the experimental results for magnetization as a function of temperature and magnetic field indicates that the first-to-second order magnetic phase transformation occurs at a threshold composition of x=0.06, which is further supported by the universal curves of the normalized entropy change versus reduced temperature. The maximum magnetic entropy change measured at a magnetic field span of 50 kOe, which occurs near the Curie temperature, decreases from 10.30 to 2.15 J/kg K with the increase of x from 0.0 to 0.1. However, the relative cooling power, an important parameter for practical applications, shows a maximum value of 404 J/kg at x=0.08, which is 1.5 times greater than that observed for the undoped sample. - Highlights: • Magnetic and MCE of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3} are investigated. • Order of magnetic phase transition is dependent on the Zn doping concentration. • Although the |∆S{sub max}| decreases with increasing x, RCP increase remarkably.

Ten years of cryo-magnetic W7-X test facility construction and operation

International Nuclear Information System (INIS)

Renard, B.; Dispau, G.; Donati, A.; Genini, L.; Gournay, J.F.; Kuster, O.; Molinie, F.; Schild, T.; Touzery, R.; Vieillard, L.; Walter, C.

2011-01-01

The construction, commissioning, and operation phases of the W7-X cryo-magnetic test facility in CEA Saclay lasted ten years. The large diversity of equipments called, specialties involved and problems solved attest the expertise that was required to operate the test facility and test the coils. Nearly one hundred cryogenic tests were performed on the seventy W7-X coils, at a rate always increasing, using two cryostats each holding two coils. This paper presents the test facility and its operation first, the cryogenic difficulties that were confronted with their solutions, the electro-magnetic difficulties encountered along with corrective actions, and finally the instrumentation and data acquisition aspects. (authors)

Fabrication and testing of W7-X pre-series target elements

International Nuclear Information System (INIS)

Boscary, J; Boeswirth, B; Greuner, H; Grigull, P; Missirlian, M; Plankensteiner, A; Schedler, B; Friedrich, T; Schlosser, J; Streibl, B; Traxler, H

2007-01-01

The assembly of the highly-loaded target plates of the WENDELSTEIN 7-X (W7-X) divertor requires the fabrication of 890 target elements (TEs). The plasma facing material is made of CFC NB31 flat tiles bonded to a CuCrZr copper alloy water-cooled heat sink. The elements are designed to remove a stationary heat flux and power up to 10 MW m -2 and 100 kW, respectively. Before launching the serial fabrication, pre-series activities aimed at qualifying the design, the manufacturing route and the non-destructive examinations (NDEs). High heat flux (HHF) tests performed on full-scale pre-series TEs resulted in an improvement of the design of the bond between tiles and heat sink to reduce the stresses during operation. The consequence is the fabrication of additional pre-series TEs to be tested in the HHF facility GLADIS. NDEs of this bond based on thermography methods are developed to define the acceptance criteria suitable for serial fabrication

Electron thermal conductivity from heat wave propagation in Wendelstein 7-AS

Energy Technology Data Exchange (ETDEWEB)

Giannone, L.; Erckmann, V; Gasparino, U; Hartfuss, H J; Kuehner, G; Maassberg, H; Stroth, U; Tutter, M [Association Euratom-Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); W7-AS Team; ECRH Group IPF Stuttgart; Gyrotron Group KFK Karlsruhe

1992-11-01

Heat wave propagation experiments have been carried out on the Wendelstein 7-AS stellarator. The deposition of electron cyclotron resonance heating power is highly localized in the plasma centre, so that power modulation produces heat waves which propagate away from the deposition volume. Radiometry of the electron cyclotron emission is used to measure the generated temperature perturbation. The propagation time delay of the temperature perturbation as a function of distance to the power deposition region is used to determine the electron thermal conductivity [chi][sub e]. This value is then compared with the value determined by global power balance. In contrast to sawtooth propagation experiments in tokamaks, it is found that the value of [chi][sub e] from heat wave propagation is comparable to that calculated by power balance. In addition, inward propagating waves were produced by choosing a power deposition region away from the plasma centre. Experiments were carried out at 70 GHz in the ordinary mode and at 140 GHz in the extraordinary mode. Variations of the modulation power amplitude have demonstrated that the inferred value of [chi][sub e] is independent of the amplitude of the induced temperature perturbations. (author). 29 refs, 11 figs, 5 tabs.

Optimization of a quench detection system for superconducting magnets

International Nuclear Information System (INIS)

Borlein, M.

2004-12-01

Subject of this report is the detection of a quench in a superconducting magnet. For the safe operation of superconducting magnets one of the most important issues is the quench detection system which controls the superconducting state of the magnet and triggers a safety discharge if necessary. If it comes to a breakdown of the superconductivity (quench), the magnet has to be discharged very quickly to avoid any damage or danger for the magnet or its environment. First an introducing overview is given. Next different methods of quench detection will be presented, partially on the basis of existing quench detection systems and the applicability of these methods in different states of the magnet operation will be shown. The different quench detection methods are compared and evaluated partially by using test experiments described in the appendix. As an application example this report contains a proposal for the quench detection system for the Wendelstein 7-X facility, actually built by the Institute for Plasma Physics, Garching [de

Phase contrast imaging diagnostic for the Wendelstein 7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Boettger, Lukas-Georg; Grulke, Olaf [Max Planck Institute for Plasma Physics, 17491 Greifswald (Germany)

2016-07-01

The phase contrast imaging (PCI) diagnostic allows for non-invasive measurements of density fluctuations in high temperature plasmas. Since the index of refraction in a plasma is a function of the electron density, an incoming laser beam experiences a phase shift, which can be converted to intensity variations via interference after passing a phase plate. Generally speaking, the signal contains only the line-integrated information along the beam path. This limitation can be circumvented by using the fact that the density fluctuations form filamentary structures that are well aligned with the local magnetic field. If the magnetic field direction significantly varies along the beam path, optical filtering allows for localization of the density fluctuations. In order to identify the best diagnostic position regarding localization performance three figures of merit are introduced. They allow for quantitative comparison of different lines of sight and different magnetic field configurations. The results of the optimization process and a comparison with other fusion experiments are shown in this contribution.

Architecture of central control system for the 10 MW ECRH-plant at W7-X

Energy Technology Data Exchange (ETDEWEB)

Braune, H. [Max-Plank-Institut fuer Plasmaphysik, Euratom Association Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)], E-mail: harald.braune@ipp.mpg.de; Brand, P. [Universitaet Stuttgart, Institut fuer Plasmaforschung Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Erckmann, V.; Jonitz, L. [Max-Plank-Institut fuer Plasmaphysik, Euratom Association Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Leonhardt, W.; Mellein, D. [Forschungszentrum Karlsruhe, Association EURATOM-FZK, IHM, FZK, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Michel, G. [Max-Plank-Institut fuer Plasmaphysik, Euratom Association Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Mueller, G. [Universitaet Stuttgart, Institut fuer Plasmaforschung Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Purps, F. [Max-Plank-Institut fuer Plasmaphysik, Euratom Association Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Schlueter, K.-H. [Universitaet Stuttgart, Institut fuer Plasmaforschung Pfaffenwaldring 31, D-70569 Stuttgart (Germany); Winkler, M. [Max-Plank-Institut fuer Plasmaphysik, Euratom Association Teilinstitut Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)

2007-10-15

Electron Cyclotron Resonance Heating (ECRH) is the main heating method for the Wendelstein 7-X stellarator (W7-X) which is presently under construction at IPP Greifswald. The mission of W7-X is to demonstrate the inherent steady state capability of stellarators at reactor relevant plasma parameters. A modular 10 MW ECRH-plant at 140 GHz with 1 MW CW-capability power for each module is also under construction to support the scientific objectives. The commissioning of the ECRH-plant is well under way; three gyrotrons are operational. The strict modular design allows to operate each gyrotron separately and independent from all others. The ECRH-plant consists of many devices such as gyrotrons and high voltage power supplies, superconductive magnets, collector sweep coils, gyrotron cooling systems with many water circuits and last but not least the quasi-optical transmission line for microwaves with remote controlled mirrors and further water cooled circuits. All these devices are essential for a CW operation. A steady state ECRH has specific requirements on the stellarator machine itself, on the microwave sources, transmission elements and in particular on the central control system. The quasi steady state operation (up to 30 min) asks for real time microwave power adjustment during the different segments of one stellarator discharge. Therefore, the ECRH-plant must operate with a maximum reliability and availability. A capable central control system is an important condition to achieve this goal. The central control system for the 10 MW ECRH-plant at W7-X comprises three main parts. In detail these are the voltage and current regulation of each gyrotron, the interlock system to prevent the gyrotrons from damages and the remote control system based on a hierarchy set of PLCs and computers. The architecture of this central control system is presented.

Overview video diagnostics for the W7-X stellarator

Energy Technology Data Exchange (ETDEWEB)

Kocsis, G., E-mail: kocsis.gabor@wigner.mta.hu [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary); Baross, T. [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary); Biedermann, C. [Max-Planck-Institute for Plasma Physics, 17491 Greifswald (Germany); Bodnár, G.; Cseh, G.; Ilkei, T. [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary); König, R.; Otte, M. [Max-Planck-Institute for Plasma Physics, 17491 Greifswald (Germany); Szabolics, T.; Szepesi, T.; Zoletnik, S. [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary)

2015-10-15

Considering the requirements of the newly built Wendelstein 7-X stellarator a ten-channel overview video diagnostic system was developed and is presently under installation. The system covering the whole torus interior can be used not only to observe the plasma but also to detect irregular operational events which are dangerous for the stellarator itself and to send automatic warning for the machine safety. The ten tangential AEQ ports used by the diagnostic remain under atmospheric pressure, the vacuum/air interface is at the front window located at the plasma side of the AEQ port. The optical vacuum window is protected by a cooled pinhole. The Sensor Module (SM) of the intelligent camera (EDICAM) – developed especially for this purpose – is located directly behind the vacuum window. EDICAM is designed to simultaneously record several regions of interest of its CMOS sensor with different frame rate and to detect various predefined events in real time. The air cooled SM is fixed by a docking mechanism which can preserve the pointing of the view. EDICAM can withstand the magnetic field (∼3 T), the neutron and gamma fluxes expected in the AEQ port. In order to adopt the new features of the video diagnostics system both control and data acquisition and visualization and data processing softwares are developed.

Overview video diagnostics for the W7-X stellarator

International Nuclear Information System (INIS)

Kocsis, G.; Baross, T.; Biedermann, C.; Bodnár, G.; Cseh, G.; Ilkei, T.; König, R.; Otte, M.; Szabolics, T.; Szepesi, T.; Zoletnik, S.

2015-01-01

Considering the requirements of the newly built Wendelstein 7-X stellarator a ten-channel overview video diagnostic system was developed and is presently under installation. The system covering the whole torus interior can be used not only to observe the plasma but also to detect irregular operational events which are dangerous for the stellarator itself and to send automatic warning for the machine safety. The ten tangential AEQ ports used by the diagnostic remain under atmospheric pressure, the vacuum/air interface is at the front window located at the plasma side of the AEQ port. The optical vacuum window is protected by a cooled pinhole. The Sensor Module (SM) of the intelligent camera (EDICAM) – developed especially for this purpose – is located directly behind the vacuum window. EDICAM is designed to simultaneously record several regions of interest of its CMOS sensor with different frame rate and to detect various predefined events in real time. The air cooled SM is fixed by a docking mechanism which can preserve the pointing of the view. EDICAM can withstand the magnetic field (∼3 T), the neutron and gamma fluxes expected in the AEQ port. In order to adopt the new features of the video diagnostics system both control and data acquisition and visualization and data processing softwares are developed.

7. IAEA Technical Meeting on Steady State Operation of Magnetic Fusion Devices - Booklet of abstracts

International Nuclear Information System (INIS)

2015-01-01

This meeting has provided an appropriate forum to discuss current issues covering a wide range of technical topics related to the steady state operation issues and also to encourage forecast of the ITER performances. The technical meeting includes invited and contributed papers. The topics that have been dealt with are: 1) Superconducting devices (ITER, KSTAR, Tore-Supra, HT-7U, EAST, LHD, Wendelstein-7-X,...); 2) Long-pulse operation and advanced tokamak physics; 3) steady state fusion technologies; 4) Long pulse heating and current drive; 5) Particle control and power exhaust, and 6) ITER-related research and development issues. This document gathers the abstracts

Limit analysis of narrow support elements in W7-X considering the serration effect of the stress-strain relation at 4 K

International Nuclear Information System (INIS)

Briani, E.; Gianini, C.; Lucca, F.; Marin, A.; Fellinger, J.; Bykov, V.

2011-01-01

The magnet support system of the Wendelstein 7-X (W7-X) fusion stellarator includes challenging components, called Narrow Support Elements (NSEs), placed between the Non Planar Coils (NPCs) at the inboard side and aimed at reducing deformation of the coils. NSEs are small contact elements, with special coating to reduce friction, that have to withstand high compressive and shear forces. The objective of this article is to demonstrate the structural reliability of the NSEs under electromagnetic loading (EML), taking into account in a conservative way the relevant material properties at cryogenic temperatures. To this purpose, an appropriate parametric local Finite Element (FE) model of one highly loaded NSE with its components (pad, pad frame and counter pad) and of a portion of the coils has been developed with ABAQUS code and isotropic elastic-plastic material model with hardening/softening has been used, in order to include the serration effect at 4 K. Different mechanical limit analyses have been performed including consecutive steps of shrink fitting the NSEs in the coils, cooling down to 4 K and gradual increasing of the coil displacements induced by the EML.

Limit analysis of narrow support elements in W7-X considering the serration effect of the stress-strain relation at 4 K

Energy Technology Data Exchange (ETDEWEB)

Briani, E., E-mail: erica.briani@ltcalcoli.it [L.T.Calcoli SaS, Piazza Prinetti 26/B, 23807, Merate (Saint Lucia) (Italy); Gianini, C.; Lucca, F.; Marin, A. [L.T.Calcoli SaS, Piazza Prinetti 26/B, 23807, Merate (Saint Lucia) (Italy); Fellinger, J.; Bykov, V. [MPI fur Plasmaphysik (IPP) Wendelsteinstrasse I, D-17491 Greifswald (Germany)

2011-10-15

The magnet support system of the Wendelstein 7-X (W7-X) fusion stellarator includes challenging components, called Narrow Support Elements (NSEs), placed between the Non Planar Coils (NPCs) at the inboard side and aimed at reducing deformation of the coils. NSEs are small contact elements, with special coating to reduce friction, that have to withstand high compressive and shear forces. The objective of this article is to demonstrate the structural reliability of the NSEs under electromagnetic loading (EML), taking into account in a conservative way the relevant material properties at cryogenic temperatures. To this purpose, an appropriate parametric local Finite Element (FE) model of one highly loaded NSE with its components (pad, pad frame and counter pad) and of a portion of the coils has been developed with ABAQUS code and isotropic elastic-plastic material model with hardening/softening has been used, in order to include the serration effect at 4 K. Different mechanical limit analyses have been performed including consecutive steps of shrink fitting the NSEs in the coils, cooling down to 4 K and gradual increasing of the coil displacements induced by the EML.

Wendelstein VII-A in torsatron mode

International Nuclear Information System (INIS)

Harmeyer, E.; Kisslinger, J.; Rau, F.; Wobig, H.

1985-03-01

Variable shear - positive or negative, up to about 20 percent - can be introduced into the Wendelstein VII-A Stellarator vacuum field configuration by different currents in the two helix systems, and balancing the resulting vertical field. (orig.)

Radiation effects on superconducting fusion magnet components

International Nuclear Information System (INIS)

Weber, H.W.

2011-01-01

Nuclear fusion devices based on the magnetic confinement principle heavily rely on the existence and performance of superconducting magnets and have always significantly contributed to advancing superconductor and magnet technology to their limits. In view of the presently ongoing construction of the tokamak device ITER and the stellerator device Wendelstein 7X and their record breaking parameters concerning size, complexity of design, stored energy, amperage, mechanical and magnetic forces, critical current densities and stability requirements, it is deemed timely to review another critical parameter that is practically unique to these devices, namely the radiation response of all magnet components to the lifetime fluence of fast neutrons and gamma rays produced by the fusion reactions of deuterium and tritium. I will review these radiation effects in turn for the currently employed standard "technical" low temperature superconductors NbTi and Nb 3 Sn, the stabilizing material (Cu) as well as the magnet insulation materials and conclude by discussing the potential of high temperature superconducting materials for future generations of fusion devices, such as DEMO. (author)

Magnetic tri-axial orientation in (Y1-xErx)2Ba4Cu7O15-y superconductors

International Nuclear Information System (INIS)

Horii, S.; Okuhira, S.; Yamaki, M.; Haruta, M.; Maeda, T.; Shimoyama, J.

2011-01-01

(Y 1-x Er x ) 2 Ba 4 Cu 7 O 15-y [(Y,Er)247] was synthesized for clarifying a magnetic role of Er ion. The three magnetization axes of (Y,Er)247 were obtained from tri-axial orientation using a modulated rotation magnetic field. Magnetic anisotropy of Er ion is roughly ten times higher than that for Y247 at room temperature. Importance of rare-earth ions was shown for reduction of required magnetic fields in the tri-axial magnetic orientation. We report the tri-axial grain-orientation effects under a modulated rotation magnetic field for (Y 1-x Er x ) 2 Ba 4 Cu 7 O y [(Y, Er)247]. The magnetic easy axis at room temperature was drastically changed around x ∼ 0.1; however, the Er-doping levels for the conversion of magnetic easy axes from the c-axis to the ab-direction and from the a- to b-axes were quite different. Tri-axial single-ion magnetic anisotropy of Er 3+ was roughly 10 times greater than tri-axial magnetic anisotropy generated by both the superconducting CuO 2 plane and the blocking Cu-O chain layer. An appropriate choice of rare-earth (RE) ions in RE-based cuprate superconductors enables the reduction of the required magnetic field for the production of bulks and thick films based on the magnetic orientation technique.

Glass forming ability and magnetic properties of Co(40.2−x)Fe(20.1+x)Ni6.7B22.7Si5.3Nb5 (x=0–10) bulk metallic glasses produced by suction casting

International Nuclear Information System (INIS)

Sarlar, Kagan; Kucuk, Ilker

2015-01-01

The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) have a supercooled liquid region (∆T x ) of about 44 K. The saturation magnetizations (J s ) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J s 0.62−0.81 T with a low H c of 2−289 A/m of the alloys

Design and Fabrication of the Superconducting Bussystem for the Stellarator W7-X

International Nuclear Information System (INIS)

Sauer, M.; Giesen, B.; Charl, A.

2006-01-01

In the framework of cooperation with the Max-Planck-Institute for plasma physics (IPP) essential work packages of the superconducting stellarator Wendelstein 7-X (which is presently under construction at Greifswald, Germany) have been taken over by the Forschungszentrum Juelich (FZJ). One of these packages is the design, construction, qualification, manufacturing and assembly of the superconducting three-dimensional bussystem and its appropriate supports. An overall concept of the project was elaborated with the goal to optimize manufacturing steps, to simplify the system assembly and to provide easy transportation. In order to compensate the magnetic stray fields generated by the bus currents and to facilitate the bus assembly, a suitable bus topology was developed. For checking the geometry of the bent buses and to examine the buses assembly a 1:1 model of one W7-X section (72 o ) has been built. An insulation set up was developed and different samples have been fabricated. For qualification the insulation was examined as follows: - high voltage insulation checks including measurements of the Paschen firmness, - thermal tests and mechanical bending under cryo-temperatures at 77 K, - leakage and high pressure tests to simulate quench situations and - vacuum compatibilities of the materials and methods used. The design will be shown, calculation of magnetic fields and forces are presented. For series production of the 121 buses a production line has been installed. The fabrication process and its main appropriate steps will be presented: 1. Straightening of the superconductor on a rolling machine 2. Rounding on a special turning lathe, required to facilitate 3-dimensional bending 3. Bending on a 3-D-bending machine 4. Checking of geometry on the 1:1 model 5. Electrical insulation and conductive lacquer coat applied by hand 6. Vacuum and high voltage test at several pressure steps (Paschen test) inside bellow tube 7. Transportation in bundle of 6 buses to Greifswald

Cold test measurements on components of the 1 MW, 140 GHz, CW gyrotron for the stellarator Wendelstein 7-X

International Nuclear Information System (INIS)

Dammertz, G.; Alberti, S.; Arnold, A.; Giguet, E.; LeGoff, Y.; Thumm, M.

2001-01-01

For the development of a 1 MW, 140 GHz gyrotron for CW operation which will be installed at the stellarator facility Wendelstein 7-X at IPP Greifswald, a collaboration between different European research institutes and an industrial company has been established. In order to prove the proper functioning of the millimeter wave components installed in the gyrotron -- such as the cavity, the waveguide taper and the quasioptical mode converter -- these components should be cold tested, preferably before installation. However, due to lack of time as well as long delivery times, this was not possible. Therefore, two units of the quasioptical mode converter and the cavity were fabricated with identical geometry, one of those being used for measurements on the low power test device. To perform these cold tests for tapers and mode converters, the gyrotron cavity output mode has to be simulated. This means that a high order rotating mode (TE 28,8 mode) must be generated at low power. This can be achieved by means of a mode generator consisting of two mirrors and a coaxial cavity with a perforated outer wall. Before applying the mode generator to the components, its proper behavior and the accurate alignment of the system must be verified either by radiation pattern measurements or k-spectrometer measurements. As the coupling through the holes of the k-spectrometer is extremely low, a special vector network analyzer with a dynamic range of at least 100 dB had to be developed. This has been achieved by integration of a phase locked backward-wave oscillator with a line width of 100 Hz and an output power of 10 mW. A non-destructive measurement of the resonance frequency and the quality factor of the cavity does not seem possible. The second cavity will be prepared for the cold measurement by drilling a small radial hole into its wall in the plane of the field maximum. This hole is then used for the input coupling. The accuracy required for this hole is rather critical. The

User Control Interface for W7-X Plasma Operation

International Nuclear Information System (INIS)

Spring, A.; Laqua, H.; Schacht, J.

2006-01-01

The WENDELSTEIN 7-X fusion experiment will be a highly complex device operated by a likewise complex control system. The fundamental configuration of the W7-X control system follows two major design principles: It reflects the strict hierarchy of the machine set-up with a set of subordinated components, which in turn can be run autonomously during commissioning and testing. Secondly, it links the basic machine operation (mainly given by the infrastructure status and the components readiness) and the physics program execution (i.e. plasma operation) on each hierarchy level and on different time scales. The complexity of the control system implies great demands on appropriate user interfaces: specialized tools for specific control tasks allowing a dedicated view on the subject to be controlled, hiding complexity wherever possible and reasonable, providing similar operation methods on each hierarchy level and both manual interaction possibilities and a high degree of intelligent automation. The contribution will describe the operation interface for experiment control including the necessary links to the machine operation. The users of ' Xcontrol ' will be both the W7-X session leaders during plasma discharge experiments and the components' or diagnostics' operators during autonomous mode or even laboratory experiments. The main ' Xcontrol ' features, such as program composition and validation, manual and automatic control instruments, resource survey, and process monitoring, will be presented. The implementation principles and the underlying communication will be discussed. (author)

Simulation of neutron fluxes around the W7-X Stellarator

International Nuclear Information System (INIS)

Andersson, Jenny

1999-12-01

A new fusion experiment, the WENDELSTEIN 7-X Stellarator (W7-X), will be undertaken in Greifswald in Germany. Measurements of the neutron flux will provide information on fusion reaction rates and possibly also on ion temperatures as function of time. For this purpose moderating neutron counters will be designed, tested, calibrated and eventually used at W7-X. Extensive Monte-Carlo simulations have been performed in order to select the most suitable detector and moderator combination with a flat response function and highest achievable efficiency. Different detector configurations with different moderating materials have been tried out, showing that a 32 cm thick graphite moderating BF 3 -counter gives the desired flat response and sufficient efficiency. Neutron spectra calculations have been made for different torus models and the influence of floor, walls and ceiling (i.e. reactor hall) have been investigated. Presented results suggest that a more detailed torus model significantly reduces the number of neutron counts at the detector. Calculations including the reactor hall indicate a tendency of shifting the neutron spectra towards the thermal region. The main part of the scattered neutrons are back-scattered from the floor. Finally, calculations on the graphite moderating BF 3 -counter in the detailed torus environment were performed in order to assess the absolute response function under the influence of the reactor hall. The results show that the detector count rate will increase by only 5-7 % when the reactor hall is taken into account. With a stellarator generating 10 12 to 10 16 neutrons per second the detector count rate will be 2x10 5 to 2x10 9 neutrons per second

Simulation of neutron fluxes around the W7-X Stellarator

Energy Technology Data Exchange (ETDEWEB)

Andersson, Jenny

1999-12-01

A new fusion experiment, the WENDELSTEIN 7-X Stellarator (W7-X), will be undertaken in Greifswald in Germany. Measurements of the neutron flux will provide information on fusion reaction rates and possibly also on ion temperatures as function of time. For this purpose moderating neutron counters will be designed, tested, calibrated and eventually used at W7-X. Extensive Monte-Carlo simulations have been performed in order to select the most suitable detector and moderator combination with a flat response function and highest achievable efficiency. Different detector configurations with different moderating materials have been tried out, showing that a 32 cm thick graphite moderating BF{sub 3} -counter gives the desired flat response and sufficient efficiency. Neutron spectra calculations have been made for different torus models and the influence of floor, walls and ceiling (i.e. reactor hall) have been investigated. Presented results suggest that a more detailed torus model significantly reduces the number of neutron counts at the detector. Calculations including the reactor hall indicate a tendency of shifting the neutron spectra towards the thermal region. The main part of the scattered neutrons are back-scattered from the floor. Finally, calculations on the graphite moderating BF{sub 3} -counter in the detailed torus environment were performed in order to assess the absolute response function under the influence of the reactor hall. The results show that the detector count rate will increase by only 5-7 % when the reactor hall is taken into account. With a stellarator generating 10{sup 12} to 10{sup 16} neutrons per second the detector count rate will be 2x10{sup 5} to 2x10{sup 9} neutrons per second.

Suppression of the long-range magnetic order in Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} upon substitution of Fe for Mn

Energy Technology Data Exchange (ETDEWEB)

Volkov, N.V. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Eremin, E.V., E-mail: eev@iph.krasn.ru [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Bayukov, O.A.; Sablina, K.A. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Solov’ev, L.A. [Institute of Chemistry and Chemical Technology, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660049 (Russian Federation); Velikanov, D.A.; Mikhashenok, N.V.; Osetrov, E.I. [Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk 660036 (Russian Federation); Schefer, J.; Keller, L. [Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Boehm, M. [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble, Cedex 9 (France)

2013-09-15

Structure and magnetic properties of Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} single crystals with x=0–0.2 grown by spontaneous crystallization from solution in melt have been investigated. All the crystals belong to the hexagonal space group P6{sub 3}/mcm. The magnetic properties appeared to be strongly dependent on the iron doping level. At small (x=0.05) dopant concentrations, the value of magnetization and Neel temperature T{sub N} decrease insignificantly (T{sub N}=70 K). With increasing x, the three-dimensional magnetic ordering does not occur and temperature dependences of magnetization at x≥0.1 exhibit spin-glass-like features in the low-temperature region. - Highlights: • In the first time the single crystals of Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} were grown. • The valence and locations of iron ions in crystal were determined. • Suppression of the long-range magnetic order in Pb{sub 3}(Mn{sub 1−x}Fe{sub x}){sub 7}O{sub 15} was discovered.

Density, temperature, and potential fluctuation measurements by the swept Langmuir probe technique in Wendelstein 7-AS

International Nuclear Information System (INIS)

Giannone, L.; Balbin, R.; Niedermeyer, H.; Endler, M.; Herre, G.; Hidalgo, C.; Rudyj, A.; Theimer, G.; Verplanke, P.

1994-01-01

In the Wendelstein 7-AS stellarator (W7-AS) [Plasma Phys. Controlled Fusion 33, 1591 (1991)], current-voltage characteristics of the Langmuir probe at sweep frequencies in the range 400 kHz to 1 MHz were measured and it was found that the mean and fluctuation values of the ion saturation current, floating potential, and electron temperature were independent of the sweep frequency. A radial scan in the vicinity of the velocity shear layer was performed. The simultaneous sweeping of 3 probe tips showed a statistically significant spatial coherence of the fluctuations in the poloidal direction and a decrease in spatial coherence of the fluctuations with increasing tip separation could be demonstrated. The observation of a change in the propagation direction of fluctuations as the shear layer was crossed and a calculation of the transport spectrum show that the swept probe method is capable of reproducing known results. Apparent temperature fluctuations, due to variations of density and potential during a sweep, are shown by simulations to be only of importance at frequencies above half the Nyquist frequency

Magnetic resistance in Tm(Ba2x Prx)Cu3 O7+δ

International Nuclear Information System (INIS)

Mokhtari, Z.; Akhavan, M.

2003-01-01

The magnetoresistance of single phase polycrystalline Tm(Ba 2x Pr x )Cu 3 O 7+δ samples have been studied within AH model. The derives power law dependence of pinning energy and critical current density to applied magnetic field (H -n ) shows that the power factor increases with the increases of Pr content, with the average value of n≅0.2. It shows that the Pr doping plays the role of weak link. It is noticeable that the behavior of x=0 samples. This maybe due to the intragrain properties of the sample

Experimental design: Case studies of diagnostics optimization for W7-X

International Nuclear Information System (INIS)

Dreier, H.; Dinklage, A.; Fischer, R.; Hartfuss, H.-J.; Hirsch, M.; Kornejew, P.; Pasch, E.; Turkin, Yu.

2005-01-01

The preparation of diagnostics for Wendelstein 7-X is accompanied by diagnostics simulations and optimization. Starting from the physical objectives, the design of diagnostics should incorporate predictive modelling (e.g. transport modelling) and simulations of respective measurements. Although technical constraints are governing design considerations, it appears that several design parameters of different diagnostics can be optimized. However, a general formulation for fusion diagnostics design in terms of optimization is lacking. In this paper, first case studies of Bayesian experimental design aiming at applications on W7-X diagnostics preparation are presented. The information gain of a measurement is formulated as a utility function which is expressed in terms of the Kullback-Leibler divergence. Then, the expected range of data is to be included and the resulting expected utility represents the objective for optimization. Bayesian probability theory gives a framework allowing us for an appropriate formulation of the design problem in terms of probability distribution functions. Results are obtained for the information gain from interferometry and for the design of polychromators for Thomson scattering. For interferometry, studies of the choice of line-of-sights for optimum signal and for the reproduction of gradient positions are presented for circular, elliptical and W7-X geometries. For Thomson scattering, the design of filter transmissions for density and temperature measurements are discussed. (author)

Continuity and enhancement of quality management during commissioning of W7-X

Energy Technology Data Exchange (ETDEWEB)

Vilbrandt, Reinhard, E-mail: reinhard.vilbrandt@ipp.mpg.de; Bosch, Hans-Stephan; Feist, Jost-Henrich; Klinger, Thomas

2015-10-15

Highlights: • Commissioning follows the W7-X structure into appropriate components, subsystems and systems. • Local and integrated commissioning steps are carried out alternately. • An exact and detailed preparation of all commissioning is absolutely necessary. • Templates support instruction manuals, safety analyses, and commissioning instructions. • Because of safety special attention must be paid to the first putting into service. - Abstract: The commissioning of Wendelstein 7-X, the first numerically optimized stellarator, is a new phase in the project. The general planning and execution of the commissioning of the entire W7-X system follow its structure into appropriate components, subsystems and systems. The approach for taking these systems into operation will lead to so-called local commissioning which is usually executed for individual systems in connection with the necessary peripheral devices and auxiliary systems. The subsequent step-wise testing and commissioning of the systems in connection with the central device of W7-X, including the central safety control, and the central data acquisition system is performed in the second step, the so-called integrated commissioning. This leads directly to the preparation of first plasma operation. New organizational and quality management elements have been added to the running system, or existing, proven tools have been modified. The major new organizational structures and tasks and the quality planning and assurance tools are described in more detail. The experience during the first commissioning steps of the vacuum and cryogenic systems is outlined.

Comparison of silicon drift detectors made by Amptek and PNDetectors in application to the PHA system for W7-X

Directory of Open Access Journals (Sweden)

Krawczyk Natalia

2016-12-01

Full Text Available The paper presents comparison of two silicon drift detectors (SDD, one made by Amptek, USA, and the second one by PNDetector, Germany, which are considered for a soft X-ray diagnostic system for W7-X. The sensitive area of the first one is 7 mm2 × 450 μm and the second one is 10 mm2 × 450 μm. The first detector is cooled by a double-stage Peltier element, while the second detector is cooled by single-stage Peltier element. Each one is equipped with a field-effect transistor (FET. In the detector from Amptek, the FET is mounted separately, while in the detector from PNDetector, the FET is integrated on the chip. The nominal energy resolution given by the producers of the first and the second one is 136 eV@5.9 keV (at -50°C and 132 eV@5.9 keV (at -20°C, respectively. Owing to many advantages, the investigated detectors are good candidates for soft X-ray measurements in magnetic confinement devices. They are suitable for soft X-ray diagnostics, like the pulse height analysis (PHA system for the stellarator Wendelstein 7-X, which has been developed and manufactured at the Institute of Plasma Physics and Laser Microfusion (IPPLM, Warsaw, in collaboration with the Max Planck Institute for Plasma Physics (IPP, Greifswald. The diagnostic is important for the measurements of plasma electron temperature, impurities content, and possible suprathermal tails in the spectra. In order to choose the best type of detector, analysis of technical parameters and laboratory tests were done. Detailed studies show that the most suitable detector for the PHA diagnostics is the PNDetector.

Completion of designing and manufacturing of the coil support structure of W7-X

International Nuclear Information System (INIS)

Chauvin, Didier; Koppe, Torsten; Cardella, Antonio; Missal, Bernd; Pilopp, Dirk; Di Bartolo, Giovanni; Camin, Rocio; Gonzales, Ivan; Giordano, Luca; Langone, Stefano

2011-01-01

In February 2000, the project called coil support structure for the Wendelstein 7-X fusion machine was started. Since October 2009 the full production of this big (80 tons) and complex component is now completed and delivered at IPP Greifswald. The W7-X coil system consists of 20 planar and 50 non-planar coils. They are supported by a pentagonal 10 m diameter, 2.5 m high called coil support structure (CSS). The CSS is divided into five modules and each module consists of two equal half modules around the radial axis. Currently, the five modules were successfully assembled with the coils meeting the tight manufacturing tolerances. Designing, structural calculation, raw material procurement, welding and soldering technologies, milling, drilling, accurate machining, helium cooling pipe forming, laser metrology, ultra sonic cleaning and vacuum test are some of the key points used all along this successful manufacturing process. The lessons learned in the large scale production of this difficult kind of support structure will be presented as relevant experience for the realization of similar systems for future fusion devices, such as ITER.

Automated jitter correction for IR image processing to assess the quality of W7-X high heat flux components

International Nuclear Information System (INIS)

Greuner, H; De Marne, P; Herrmann, A; Boeswirth, B; Schindler, T; Smirnow, M

2009-01-01

An automated IR image processing method was developed to evaluate the surface temperature distribution of cyclically loaded high heat flux (HHF) plasma facing components. IPP Garching will perform the HHF testing of a high percentage of the series production of the WENDELSTEIN 7-X (W7-X) divertor targets to minimize the number of undiscovered uncertainties in the finally installed components. The HHF tests will be performed as quality assurance (QA) complementary to the non-destructive examination (NDE) methods used during the manufacturing. The IR analysis of an HHF-loaded component detects growing debonding of the plasma facing material, made of carbon fibre composite (CFC), after a few thermal cycles. In the case of the prototype testing, the IR data was processed manually. However, a QA method requires a reliable, reproducible and efficient automated procedure. Using the example of the HHF testing of W7-X pre-series target elements, the paper describes the developed automated IR image processing method. The algorithm is based on an iterative two-step correlation analysis with an individually defined reference pattern for the determination of the jitter.

Glass forming ability and magnetic properties of Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses produced by suction casting

Energy Technology Data Exchange (ETDEWEB)

Sarlar, Kagan [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Physics Department, Kamil Ozdag Faculty of Sciences, Karamanoglu Mehmetbey University, YunusEmre Campus, 70100 Karaman (Turkey); Kucuk, Ilker, E-mail: ikucuk@uludag.edu.tr [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)

2015-01-15

The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) have a supercooled liquid region (∆T{sub x}) of about 44 K. The saturation magnetizations (J{sub s}) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J{sub s} 0.62−0.81 T with a low H{sub c} of 2−289 A/m of the alloys.

Results of the examinations of the W7-X pre-series target elements

International Nuclear Information System (INIS)

Boscary, J.; Boeswirth, B.; Greuner, H.; Missirlian, M.; Schedler, B.; Scheiber, K.; Schlosser, J.; Streibl, B.

2007-01-01

The target elements of the WENDELSTEIN 7-X (W7-X) divertor are designed to sustain a stationary heat flux of 10 MW/m 2 and to remove a maximum power of 100 kW. CFC Sepcarb NB31 tiles are bonded to a water-cooled CuCrZr heat sink in two steps: active metal casting (AMC) of an AMC -copper interlayer to CFC tiles, electron beam welding (EBW) or hot isostatic pressing (HIP) of the AMC -NB31 tiles to CuCrZr. The fabrication of the whole amount of CFC NB31 has been completed. The key target of the pre-series phase is the qualification of this bond based on a series of examinations. The introduction of silicon during the AMC process significantly improved the strength of the joint between CFC and AMC -copper. The strength of the bond is preserved after either EBW or HIP processes. High heat flux testing carried out in the ion beam facility GLADIS exhibited a too high percentage of defective tiles. Pre-series activities have been extended to reduce the stress concentration at the interface between tiles and heat sink by optimizing the design

Resource checking and event handling within the W7-X segment control framework

International Nuclear Information System (INIS)

Laqua, Heike; Bluhm, Torsten; Heimann, Peter; Hennig, Christine; Kroiss, Hugo; Krom, Jon G.; Kühner, Georg; Lewerentz, Marc; Maier, Josef; Schacht, Jörg; Spring, Anett; Werner, Andreas; Zilker, Manfred

2012-01-01

Highlights: ► Support for steady state fusion experiments. ► Off-normal event handling. ► Plasma event driven control. - Abstract: ITER, Wendelstein 7-X, LHD, and TORE SUPRA are experimental facilities designed to lead the way to steady state fusion devices. These experiments require strategies to sustain a discharge in case of unforeseen events, e.g. heat overloads of plasma facing components or the failure of a plasma heating source. A recovery strategy is needed to get the discharge back for physics exploitation. For this purpose the W7-X segment control framework provides means for automated event detection along with options to formulate and initiate a recovery strategy. Besides handling of failures and degradation there are events that represent a desired plasma physical effect. An example for this kind of event is a transition to from Low to High-Confinement mode. These events indicate that a certain plasma state is reached and scientific examination can be altered thus enabling event-driven multiple experiments per discharge. Examples of both kinds of events will be presented and compared to other approaches in the community.

Effect of second introduced phase on magnetic and magnetotransport properties of (1-x)La0.7Sr0.3Mn0.9Co0.1O3/x% Ag (x=0%, 2%, 4%) nanocomposites

Science.gov (United States)

Shah, Hiral D.; Bhalodia, J. A.

2018-05-01

The structural, magnetic and magnetotransport properties of (1-x)La0.7Sr0.3Mn0.9Co0.1O3(LSMCO)/x% Ag (x=0%, 2%, 4%) nanocomposites were investigated to explore the role of second introduced phase. (1-x) LSMCO/x% Ag (x=0%, 2%, 4%) nanocomposites are prepared via solid-state reaction method. X-ray diffraction (XRD) and SEM analysis indicated that x% of Ag are not substituted into the main LSMCO phase and remains an additive to the second phase at grain boundaries [1]. The structural parameters and the reliability factors for all the samples were successfully determined by the Rietveld refinement. Magnetization and transport properties of (1-x)LSMCO/x% Ag nanocomposites have been reported. Resistivity of the composite samples increases with Ag content in comparison with the pure LSMCO, and suppressed with applied magnetic field in all the composite samples [2]. The metal-insulator transition (TMI) and accompanied paramagnetic-ferromagnetic transition (TC) temperatures decrease with increase in Ag content. The electrical resistivity of the experimental results is explored by theoretical model below TMI. The maximum MR was observed to be 55% in the x=4% sample at 5 K temperature under 7 T magnetic field, this value is larger than that of pure LSMCO (19% at 5 K and 7 T), which is encouraging for practical application. Summarily, the addition of Ag in LSMCO improves MR% values significantly due to the more grain boundary contribution and result in better physical properties of the parent manganite system.

Investigation of the commensurate magnetic structure in the heavy-fermion compound CePt2In7 using magnetic resonant x-ray diffraction

Science.gov (United States)

Gauthier, Nicolas; Wermeille, Didier; Casati, Nicola; Sakai, Hironori; Baumbach, Ryan E.; Bauer, Eric D.; White, Jonathan S.

2017-08-01

We investigated the magnetic structure of the heavy-fermion compound CePt2In7 below TN=5.34 (2 ) K using magnetic resonant x-ray diffraction at ambient pressure. The magnetic order is characterized by a commensurate propagation vector k1 /2=(1/2 ,1/2 ,1/2 ) with spins lying in the basal plane. Our measurements did not reveal the presence of an incommensurate order propagating along the high-symmetry directions in reciprocal space but cannot exclude other incommensurate modulations or weak scattering intensities. The observed commensurate order can be described equivalently by either a single-k structure or by a multi-k structure. Furthermore we explain how a commensurate-only ordering may explain the broad distribution of internal fields observed in nuclear quadrupolar resonance experiments [Sakai et al., Phys. Rev. B 83, 140408 (2011), 10.1103/PhysRevB.83.140408] that was previously attributed to an incommensurate order. We also report powder x-ray diffraction showing that the crystallographic structure of CePt2In7 changes monotonically with pressure up to P =7.3 GPa at room temperature. The determined bulk modulus B0=81.1 (3 ) GPa is similar to those of the Ce-115 family. Broad diffraction peaks confirm the presence of pronounced strain in polycrystalline samples of CePt2In7 . We discuss how strain effects can lead to different electronic and magnetic properties between polycrystalline and single crystal samples.

Magnetic properties of the Ce2Fe17-x Mn x helical magnets up to high magnetic fields

International Nuclear Information System (INIS)

Kuchin, A.G.; Mushnikov, N.V.; Bartashevich, M.I.; Prokhnenko, O.; Khrabrov, V.I.; Lapina, T.P.

2007-01-01

Magnetic properties of the Ce 2 Fe 17- x Mn x , x=0-2, alloys in magnetic fields up to 40 T are reported. The compounds with x=0.5-1 are helical antiferromagnets and those with 1 B that couple antiparallelly to the Fe moments. Easy-plane magnetic anisotropy in the Ce 2 Fe 17- x Mn x compounds weakens upon substitution of Mn for Fe. The absolute value of the first anisotropy constant in the Ce 2 Fe 17- x Mn x helical ferromagnets decreases slower with increasing temperature than that calculated from the third power of the spontaneous magnetization. Noticeable magnetic hysteresis in the Ce 2 Fe 17- x Mn x , x=0.5-2, helical magnets over the whole range of magnetic fields reflects mainly irreversible deformation of the helical magnetic structure during the magnetization of the compounds. A contribution from short-range order (SRO) magnetic clusters to the magnetic hysteresis of the helical magnets has been also estimated

Experiment planning using high-level component models at W7-X

International Nuclear Information System (INIS)

Lewerentz, Marc; Spring, Anett; Bluhm, Torsten; Heimann, Peter; Hennig, Christine; Kühner, Georg; Kroiss, Hugo; Krom, Johannes G.; Laqua, Heike; Maier, Josef; Riemann, Heike; Schacht, Jörg; Werner, Andreas; Zilker, Manfred

2012-01-01

Highlights: ► Introduction of models for an abstract description of fusion experiments. ► Component models support creating feasible experiment programs at planning time. ► Component models contain knowledge about physical and technical constraints. ► Generated views on models allow to present crucial information. - Abstract: The superconducting stellarator Wendelstein 7-X (W7-X) is a fusion device, which is capable of steady state operation. Furthermore W7-X is a very complex technical system. To cope with these requirements a modular and strongly hierarchical component-based control and data acquisition system has been designed. The behavior of W7-X is characterized by thousands of technical parameters of the participating components. The intended sequential change of those parameters during an experiment is defined in an experiment program. Planning such an experiment program is a crucial and complex task. To reduce the complexity an abstract, more physics-oriented high-level layer has been introduced earlier. The so-called high-level (physics) parameters are used to encapsulate technical details. This contribution will focus on the extension of this layer to a high-level component model. It completely describes the behavior of a component for a certain period of time. It allows not only defining simple value ranges but also complex dependencies between physics parameters. This can be: dependencies within components, dependencies between components or temporal dependencies. Component models can now be analyzed to generate various views of an experiment. A first implementation of such an analyze process is already finished. A graphical preview of a planned discharge can be generated from a chronological sequence of component models. This allows physicists to survey complex planned experiment programs at a glance.

Evolution of the structural and magnetic properties of sputtered Tb{sub x}Fe{sub 73}Ga{sub 27-x} (7 at.% ≤ x ≤ 11 at.%) thin films upon the increase of Tb content

Energy Technology Data Exchange (ETDEWEB)

Ranchal, R., E-mail: rociran@fis.ucm.es [Dpto. Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, Madrid 28040 (Spain); Fin, S. [Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara (Italy); Bisero, D. [CNISM and Dipartimento di Fisica, Università di Ferrara, Via Saragat 1, 44122 Ferrara (Italy)

2016-05-15

Tb{sub x}Fe{sub 73}Ga{sub 27-x} (7 at.% ≤ x ≤ 11 at.%) ternary alloys have been obtained by cosputtering from Tb{sub 33}Fe{sub 67} and Fe{sub 72}Ga{sub 28} targets. In contrast with other Tb–Fe–Ga compounds that consist of just one structural phase, the diffraction pattern of the Tb{sub 7}Fe{sub 73}Ga{sub 20} shows the presence of two different phases related to binary Tb–Fe and Fe–Ga alloys. This microstructure evolves as the Tb content is increased, and for a Tb of 11 at.% X-ray diffractometry only evidences the presence of a phase close to the TbFe{sub 2}. Although none of the studied samples show perpendicular magnetic anisotropy, there is a significant component of the magnetization perpendicular to the sample plane. The increase of the Tb content on the compounds from 7 at.% to 11 at.% enhances this component most probably due to the shift of the microstructure towards one similar to the TbFe{sub 2}. - Highlights: • Tb{sub x}Fe{sub 73}Ga{sub 27-x} (7 at.% ≤ x ≤ 11 at.%) thin films grown by cosputtering. • Evolution of the microstructure upon the increase of Tb. • Out of plane component of the magnetization stable up to 800 Oe.

Magnetization studies in ceramic YBa sub 2 Cu sub 3 O sub 7-x. Issledovanie namagnichennosti v keramicheskom YBa sub 2 Cu sub 3 O sub 7-x

Energy Technology Data Exchange (ETDEWEB)

Gamtsemlidze, G A; Bibiluri, D I; Gamkrelidze, K P; Mirzoeva, M I; Sharikadze, L A; Shoniya, G K [Tbilisskij Gosudarstvennyj Univ., Tbilisi (Georgia)

1991-05-01

The behaviour of ceramic YBa{sub 2}Cu{sub 3}O{sub 7-x} sample magnetization is studied as a function of the external field, prehistory and temperature using the ballistic method. The results obtained are interpreted is terms of the vortex model.

Ripple transport in a modular Helias

International Nuclear Information System (INIS)

Beidler, C.D.

1989-01-01

Neoclassical transport rates are determined for Helical-Axis Advanced Stellarators (Helias). Special emphasis is given to Wendelstein VII-X candidates, for which the magnetic field is produced by a large number of discrete non-planar coils. The investigation is concentrated on the long-mean-free-path regime where particles trapped in local ripple wells of the magnetic field make the dominant contribution to transport. For Wendelstein VII-X, such particles fall into two classes; those localized in the helical ripple common to all stellarator-type devices and those very-localized particles which are trapped in the modular ripples existing between the individual coils. Using analytical techniques it is shown that helical-ripple transport rates are substantially reduced for all Wendelstein VII-X candidates relative to classical stellarator/torsatron configurations. This reduction is most pronounced in the 1/ν regime - equivalent helical ripples of less than 1% lead to reduction factors of more than an order of magnitude - but is significant throughout the entire long-mean-free-path regime. Modular ripple transport in Wendelstein VII-X is calculated by analytically solving the appropriate bounce-averaged kinetic equation. This solution assumes a general magnetic field model and fully accounts for the deformation of modular ripples due to the presence of the other magnetic-field harmonics. Results indicate that 12 coils per field period are necessary if modular-ripple losses are to remain smaller than helical-ripple losses over the entire plasma cross section. (orig.)

The role of silicon on the microstructure and magnetic behaviour of nanostructured (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} powders

Energy Technology Data Exchange (ETDEWEB)

Hocine, M. [Département de Génie Mécanique, Faculté de Technologies, Université de M' sila, B.P 166 Ichbelia, M' sila (Algeria); UR-MPE, M' hamed Bougara University, Boumerdes, 35000 Algeria (Algeria); Guittoum, A., E-mail: aguittoum@gmail.com [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Hemmous, M. [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Martínez-Blanco, D. [SCTs, University of Oviedo, EPM, Mieres, 33600 Spain (Spain); Gorria, P. [Department of Physics, EPI, University of Oviedo, Gijón, 33203 Spain (Spain); Rahal, B. [Nuclear Research Centre of Algiers, 02Bd Frantz Fanon, BP 399, Alger-Gare, Algiers (Algeria); Blanco, J.A. [Department of Physics, University of Oviedo, CalvoSotelo St., Oviedo, 330 07 Spain (Spain); Sunol, J.J. [Departament de Fisica, Universitat de Girona, Campus de Montillivi, Girona, 17071 Spain (Spain); Laggoun, A. [UR-MPE, M' hamed Bougara University, Boumerdes, 35000 Algeria (Algeria)

2017-01-15

Single-phase(Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} nanostructured powders (x=0,5, 10, 15 and 20) have been elaborated by mechanical alloying in order to investigate the effect of silicon on the microstructure and magnetic properties of these alloys. A disordered Fe(Co, Si) solid solution with body centred cubic (bcc) crystal structure is formed after 72 h of milling for all the compositions. The addition of Si gives rise to a progressive decrease of the lattice parameter, from about 2.865 Å for the binary Fe{sub 70}Co{sub 30} compound down to 2.841 Å for the powder with x=20. The sample with the uppermost Si content exhibits the lowest value for the mean grain size (≈10 nm) as well as the largest microstrain (above 1.1%). All the samples are ferromagnetic at room temperature, although the saturation magnetization value reduces almost linearly by adding Si to the composition. A similar trend is observed for the hyperfine magnetic field obtained from the analysis of the room temperature Mössbauer spectra. The hyperfine field distributions show a broad double-peak shape for x>0, which can be ascribed to multiple local environments for the Fe atoms inside a disordered solid solution. - Highlights: • Single-phase (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} nanostructured powders (x=0, 5, 10, 15 and 20) have been elaborated by mechanical alloying. • The sample with the uppermost Si content exhibits the lowest value for the mean grain size. • The magnetic and hyperfine parameters of (Fe{sub 0.7}Co{sub 0.3}){sub 100−x}Si{sub x} depended intimately on Si content.

Proceedings of the 2. Workshop on Wendelstein VII-X

International Nuclear Information System (INIS)

Rau, F.; Leotta, G.G.

1988-01-01

The specification and final concept of W VII-X were discussed. Plasma equilibrium; plasma stability; transport; bootstrap current; plasma parameter prediction methods; boundary regions; heating; the coil system; and mechanical engineering aspects were considered. A Helias configuration with five field periods (rather than the four previously suggested) is advocated. The major radius is increased to 6.5m to alleviate plasma-wall interaction effects due to the increased number of field periods. The magnetic field is reduced from 4 to 3T, to keep the amount of superconducting material needed for coils fixed

Second order magnetic phase transition and scaling analysis in iron doped manganite La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Ginting, Dianta [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of); Nanto, Dwi [Physics Education, Syarif Hidayatullah State Islamic University, Jakarta 15412 (Indonesia); Denny, Yus Rama [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Tarigan, Kontan [Department of Mechanical Engineering, Mercu Buana University, Jakarta-Barat, Jakarta 11650 (Indonesia); Hadi, Syamsul [Department of Mechanical Engineering, State Polytechnic of Malang, East Java 65100 (Indonesia); Ihsan, Mohammad [PSTBM-BATAN, Kawasan Puspiptek Serpong, Tangerang Selatan, Banten 15314 (Indonesia); Institute of Electronic Materials, University of Wollongong, Wollongong NSW 2522 (Australia); Rhyee, Jong-Soo, E-mail: jsrhyee@khu.ac.kr [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of)

2015-12-01

We investigated magnetic properties of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x<0.09) in previous reports. When we investigate the critical behavior of the compounds near T=T{sub c} by the modified Arrott plot, Kouvel–Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε{sup −β}M(H,ε) and renormalized field h=|ε|{sup β+γ}H. Temperature-dependent effective exponents β{sub eff} and γ{sub eff} correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration. - Highlights: • The ferromagnetic phase transition is of second order in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3}. • The critical exponents are in between the 3D Heisenberg and mean-field models. • The ferromagnetic interaction becomes more itinerant by Fe-doping.

W7-AS/W7-X contributions to the 19th European conference on controlled fusion and plasma heating (Innsbruck, June 29 to July 3, 1992). - W7-AS contributions to the 10th PSI conference (Monterey, USA, March 30 to April 3, 1992)

International Nuclear Information System (INIS)

1992-07-01

This paper contains 24 contributions with the following topics: Current drive and bootstrap current in stellators; Statistical analysis of luminescence signals obbserved during pellet injection; Density fluctuation measurements by broadband heterodyne reflectometry on the W7-AS stellarator; Measurements of electron cyclotron emission during high power ECRH in the W7-AS stellarator; Density, potential and temperature fluctuation in Wendelstein 7-AS; Measurement of coherent temperature fluctuation on the stellarator Wendelstein 7-AS (W7-AS); Localized impurity flux measurements on W7-AS; The optimum ion confinement mode in W7-A stellarator induced by fast ion orbit losses of the nearly perpendicular NBI; Electron heat transport in the LMFP-regime for the stellators W7-A, W7-AS and L2; Diffusive and connective transport modelling from analysis of ECRH-stimulated electron heat wave propagation; Modified vacuum fields and compensation of islands for the stellarator W7-AS; Towards higher β in the stellarator W7-AS; Influence of electric fields on the heating efficiency in the W7-AS stellarator; Mode activity at high plasma pressure in the stellarator W7-AS; Sniffer probe measurements in W7-AS; Local neutral particle density in the W7-AS stellarator; A general solution of the ripple-averaged kinetic equation (GSRAKE); Progress in the studies of URAGAN-2M stability and transport properties; Optimization of coils and sweep coil system for W-7-X; On stationary flow in the boundary region of toroidal system; Finite ion gyro radius stabilization of ideal MHD ballooning modes in optimized stellarators; Bulk-boronized operation in the W7-AS stellarator; The impact of boundary plasma conditions on the plasma performance; Transport study on the boundary plasma of the W7-AS. (orig./MM)

Pre-series and testing route for the serial fabrication of W7-X target elements

International Nuclear Information System (INIS)

Boscary, J.; Greuner, H.; Friedrich, T.; Traxler, H.; Mendelevitch, B.; Boeswirth, B.; Schlosser, J.; Smirnow, M.; Stadler, R.

2009-01-01

The fabrication of the actively cooled high-heat flux divertor of the WENDELSTEIN 7-X stellarator (W7-X) requires the delivery of 890 target elements, which are designed to withstand a stationary heat flux of 10 MW/m 2 . The organization of the manufacturing and testing route for the serial fabrication is the result of the pre-series activities. Flat CFC Sepcarb NB31 tiles are bonded to CuCrZr copper alloy cooling structure in consecutive steps. A copper layer is active metal cast to CFC tiles, and then an OF-copper layer is added by hot isostatic pressing to produce bi-layer tiles. These tiles are bonded by electron beam welding onto the cooling structure, which was manufactured independently. The introduction of the bi-layer technology proved to be a significant improvement of the bond reliability under thermal cycling loading. This result is also the consequence of the improved bond inspections throughout the manufacturing route performed in the ARGUS pulsed thermography facility of PLANSEE. The repairing process by electron beam welding of the bonding was also qualified. The extended pre-series activities related to the qualification of fabrication processes with the relevant non-destructive examinations aim to minimize the risks for the serial manufacturing and to guarantee the steady-state operation of the W7-X divertor.

Structure and magnetism of the Sm{sub 7.5}Y{sub 2.5}Fe{sub 90−x}Si{sub x} (x=0.0, 2.5, 5.0, 7.5 and 10) alloys

Energy Technology Data Exchange (ETDEWEB)

Yang, W.Y.; Zhao, H.; Lai, Y.F.; Du, H.L.; Liu, S.Q.; Wang, C.S.; Han, J.Z.; Yang, Y.C. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Yu, X.; Qi, Z.Q. [GanZhou Fortune Electronic Co. Ltd., Jiangxi (China); Yang, J.B. [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

2017-03-15

Sm{sub 7.5}Y{sub 2.5}Fe{sub 90−x}Si{sub x} (x=0.0, 2.5, 5.0, 7.5 and 10) alloys have been prepared by arc melting method and equilibrium disordered Th{sub 2}Zn{sub 17}-type phases, (Sm,Y){sub 2−y}(Fe,Si){sub 17+2y}, with relative lower rare-earth content than the ordered Th{sub 2}Zn{sub 17}-type phase, have been obtained. Compared to the ordered Th{sub 2}Zn{sub 17}-type structure, the X-ray diffraction (XRD) intensity of the superstructure lines of the (Sm,Y){sub 2−y}(Fe,Si){sub 17+2y} decreases with the increase of the Si content and becomes zero for x=10. According to the refinement with the disordered Th{sub 2}Zn{sub 17}-type structure, the occupation rates of the R atoms at (3a) and (6c) sites tend to reach the same value with the increase of the Si content, and the lattice parameter a decreases while the lattice parameter c increases, leading to an increase of c/a. It was found that the atomic ratio of Fe(Si)/Sm(Y) in the disordered Th{sub 2}Zn{sub 17}-type structure increases with the increase of Si content and reaches a maximum value of 9.07 with x=10. The XRD diagrams of the magnetic aligned samples indicate that the easy magnetization direction (EMD) of the (Sm,Y){sub 2−y}(Fe,Si){sub 17+2y} is in the a-b plane, and the change of the EMD in a-b plane has also been observed due to the Si preferred site occupation. The remanence ratios along the easy direction are higher than that along hard direction; however, all the remanence ratios are less than 0.5. The magnetocrystalline anisotropy constant K increases first and then decreases with increasing the Si content. The Curie temperature of Sm{sub 7.5}Y{sub 2.5}Fe{sub 90−x}Si{sub x} alloys increases by about 65 K per Si. The saturation magnetization increases first and then decreases with a maximum of 135.5 emu/g observed for x=2.5 at room temperature. - Highlights: • Equilibrium disordered Th{sub 2}Zn{sub 17}-type phases (Sm,Y){sub 2-y}(Fe,Si){sub 17+2y} have been obtained. • The atomic ratio of

Fabrication and magnetic characterization of Co{sub x}Pt{sub 1-x} nanowire arrays

Energy Technology Data Exchange (ETDEWEB)

Shamaila, S. [Chinese Academy of Sciences, State Key Laboratory of Magnetism, Institute of Physics, Beijing (China); University of Engineering and Technology, Advanced Physics Laboratory, Lahore (Pakistan); Sharif, R.; Riaz, S.; Han, X.F. [Chinese Academy of Sciences, State Key Laboratory of Magnetism, Institute of Physics, Beijing (China); Khaleeq-ur-Rahman, M. [University of Engineering and Technology, Advanced Physics Laboratory, Lahore (Pakistan)

2008-08-15

Co{sub x}Pt{sub 1-x}(x{>=}0.7) alloy nanowires are grown into self-synthesized anodic alumina templates by electrodeposition. Magnetic and magnetization properties of Co{sub x}Pt{sub 1-x} alloy nanowires are measured as functions of wire length, temperature, and field orientation. X-ray diffraction shows that as-prepared CoPt nanowires are of fcc polycrystalline structure. A crossover of easy axis of magnetization is observed from parallel to perpendicular of the nanowire axis as a function of length. The coercivity (H{sub c}) and remanent squareness (SQ) of Co{sub x}Pt{sub 1-x} nanowire arrays are derived from hysteresis loops measured at various angles ({theta}) between the field and wire axis. H{sub c}({theta}) and SQ({theta}) curves show bell-shaped or otherwise bell-shaped behavior corresponding to the easy axis of their magnetization. (orig.)

Effect of doping with magnetic 3D-elements on the thermal fluctuations and critical parameters of CaLaBaCu3-x(Ni,Co)xO7-δ superconductors

International Nuclear Information System (INIS)

Rojas Sarmiento, M.P.; Landinez Tellez, D.A.; Roa-Rojas, J.

2008-01-01

Systematic measurements on conductivity fluctuation in the CaLaBaCu 3-x (Ni,Co) x O 7-δ system are reported. Samples with x=0, 0.03, 0.06, 0.09, 0.12, 0.15 and 0.18 were prepared by the standard solid-state reaction recipe. Results of resistivity measurements reveal a linear-like decreasing of the critical temperature T c with progressive substitution of magnetic elements Ni and Co into the Cu crystallographic sites. From the fluctuation analysis, above and close to T c , we found the occurrence of three- and two-dimensional Gaussian fluctuation regimes. Closer to T c , a genuinely critical regime is observed. On the Ginzburg-Landau formalism, from the reduced temperature of the three-dimensional Gaussian region and the mean field critical temperature, we have experimentally obtained the Ginzburg number for the CaLaBaCu 3-x (Ni,Co) x O 7-δ material. Then, critical magnetic field, critical current density and the jump in the specific heat at the critical temperature are calculated. Critical parameters are strongly affected by the doping with magnetic ions

Magnetic x-ray microdiffraction

Energy Technology Data Exchange (ETDEWEB)

Evans, Paul G [Computer-Aided Engineering Center, University of Wisconsin, Madison, WI 53706 (United States); Isaacs, Eric D [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439 (United States)

2006-08-07

Magnetic x-ray microdiffraction uses the structural specificity of x-ray diffraction to probe complex magnetic structures at the length scales relevant to physical phenomena including domain dynamics and phase transitions. Conventional magnetic crystallography techniques such as neutron or x-ray diffraction lack this spatial resolution. The combination of both reciprocal space and real space resolution with a rich magnetic cross section allows new microscopy techniques to be developed and applied to magnetism at the scale of single domains. Potential applications include a wide range of magnetic problems in nanomagnetism, the interaction of strain, polarization and magnetization in complex oxides and spatially resolved studies of magnetic phase transitions. We present the physical basis for x-ray microdiffraction and magnetic scattering processes, review microdiffraction domain imaging techniques in antiferromagnetic and ferromagnetic materials and discuss potential directions for studies. (topical review)

Risk management as an executive task in the construction of Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Vilbrandt, Reinhard, E-mail: Reinhard.Vilbrandt@ipp.mpg.de [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany); Bosch, Hans-Stephan; Eeten, Paul van [Max Planck Institute for Plasma Physics, EURATOM Association, Wendelsteinstr. 1, 17491 Greifswald (Germany)

2013-10-15

Highlights: Development, manufacturing, and assembly are subdivided into clearly defined steps. Because of importance, specifications are supported by clear structured templates. Database with information about changes and nonconformities allows risk assessment. To discover impacts or dependencies single risks are assigned to several subsystems. Connection to safety device database supports definition of safe operational limits. -- Abstract: To manage all risks during construction, commissioning and later operation of complex fusion experiments like the stellarator W7-X it is necessary to have a thorough and highly efficient approach. It is an executive task of the upper management to anticipate, analyze and to build up a system of measures to prevent the occurrence of potential risks or to handle the risks in such a way to minimize the impact. Very good experience has been made with the introduction of a uniform quality management system which takes into account both the processes and the technology. The most important risks for the project and the decisions made to manage them are outlined briefly.

Quality assurance on the welding work during the assembly of Wendelstein 7-X

International Nuclear Information System (INIS)

Schroeder, Michael

2011-01-01

At the Max-Planck-Institut fuer Plasmaphysik (IPP) in Greifswald (Germany) the stellarator experiment W7-X is presently being assembled. During this assembly many different weld connections are made, which are very important for the proper functionality of the experiment. This concerns mainly the structural integrity and the leak tightness. The quality requirements for the weld seams are high (mainly class B according to DIN EN ISO 5817), because the complex machine must operate reliably for more than 15 years and the possibility of any repair or change of important components is very small. To guarantee a high quality of the welds they are submitted to different tests. The applied test methods are depending on the function of the weld, the wall thickness, the seam geometry, and the material. The main test methods are visual testing (VT), penetrant testing (PT), radiographic testing (RT), ultrasonic testing (UT), leak testing (LT), permeability testing and macros. The paper will describe the application of these test methods and show their need by examples of typical weld imperfections.

Scientific component framework for W7-X using service oriented GRID middleware

International Nuclear Information System (INIS)

Werner, A.; Svensson, J.; Kuehner, G.; Bluhm, T.; Heimann, P.; Jakob, S.; Hennig, C.; Kroiss, H.; Laqua, H.; Lewerentz, M.; Riemann, H.; Schacht, J.; Spring, A.; Zilker, M.; Maier, J.

2010-01-01

Future fusion experiments, aiming to demonstrate steady state reactor operation, require physics driven plasma control based on increasingly complex plasma models. A precondition for establishing such control systems is widely automated data analysis, which can provide integration of multiple diagnostic on a large scale. Even high quality online data evaluation, which is essential for the scientific documentation of the experiment, has to be performed automatically due to the huge data sets being recorded in long discharge runs. An automated system that can handle these requirements will have to be built on reusable software components that can be maintained by the domain experts: diagnosticians, theorists, engineers and others. For Wendelstein 7-X a service oriented architecture seems to be appropriate, in which software components can be exposed as services with well defined interface contracts. Although grid computing has up to now been mainly used for remote job execution, a more promising service oriented middleware has emerged from the recent grid specification, the open grid service architecture (OGSA). It is based on stateful web services defined by the web service resource framework (WSRF) standard. In particular, the statefulness of services allows to setup complex models without unnecessary performance losses by frequent transmission of large and complex data sets. At present, the usability of this technology in the W7-X CoDaC context is under evaluation by first service implementations.

Magnetic properties and tunable magneto-caloric effect in La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 (x = 0.3, 0.5, and 0.7) compounds

Science.gov (United States)

Wu, Qiming; Wang, Xiangjie; Ding, Zan; Li, Lingwei

2018-05-01

The magnetic and magneto-caloric properties in the ternary elementals doped La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 (x = 0.3, 0.5, and 0.7) compounds were studied. With the increases of Co content x, the Curie temperature TC increases and the thermal hysteresis decreases. All the compounds undergo a second-order magnetic phase transition and exhibit a considerable reversible tunable magneto-caloric effect. The values of maximum magnetic entropy change (-ΔSMmax) and the Relative Cooling Power (RCP) are kept at same high level with different Co content. Under a magnetic field change of 0-5 T, the values of -ΔSMmax for La0.8Ce0.2Fe11.5-xCoxSi1.5C0.2 are 10.5, 10.7, and 9.8 J/kg K for x = 0.3, 0.5, and 0.7, respectively. The corresponding values of RCP are 267.1, 289.9, and 290.2 J/kg.

Structural, magnetic, magnetocaloric effect and critical behavior of La{sub 0.7}Sr{sub 0.3−x}□{sub x}MnO{sub 3}(0 ≤ x ≤ 0.05)

Energy Technology Data Exchange (ETDEWEB)

Makni-Chakroun, J., E-mail: makni.jihed@yahoo.fr [LT2S Lab, Digital Research Centre of Sfax, Sfax Technopark, BP 275, 3021 Sakiet-Ezzit (Tunisia); Sfifir, I.; Cheikhrouhou-Koubaa, W.; Koubaa, M. [LT2S Lab, Digital Research Centre of Sfax, Sfax Technopark, BP 275, 3021 Sakiet-Ezzit (Tunisia); Cheikhrouhou, A. [Material Physics Laboratory, Faculty of Sciences of Sfax, B.P. 1171, Sfax University, 3000 Sfax (Tunisia)

2017-06-15

Highlights: • The samples crystallize in the rhombohedral structure with R-3C space group. • Curie temperature T{sub C} decreases with lacuna. • (1/χ) versus temperature indicates Griffiths phase occurrence. • Result show that the paramagnetic-ferromagnetic transition is of second order. • Widom scaling relation confirms the critical exponent value. - Abstract: In this paper, we present the effect of Strontium vacancies on the structure and magnetic properties of La{sub 0.7}Sr{sub 0.3−x}□{sub x}MnO{sub 3} nano-sized compounds (x = 0; 0.01; 0.03 and 0.05), synthesized using the sol-gel method. X-ray diffraction revealed that these manganites crystallized in the rhombohedral structure with space group R3-C. From magnetization measurements as function of temperature and magnetic applied field, we have noticed a large magnetic entropy change (∆S{sub M}) around Curie temperature. ∆S{sub M} is found to decrease with the deficiency content (2.30 J/kg·K for x = 0–1.33 J/kg·K for x = 0.05 under magnetic field change µ{sub 0}∆H = 5 T). This behavior is accompanied by a slight reduction of the Curie temperature (T{sub C} = 338 and 328 K for x = 0 and 0.05, respectively). These results show that our materials are potential candidates for magnetic refrigerants working in above room temperature. The refined values of the critical exponents β, γ and δ obtained from the modified Arrott plots and Kouvel-Fisher method indicated that the behavior of the parent sample and the samples with 1and 3% of strontium-deficient are characterized by long-range mean-field behavior (with β = 0.50; γ = 1). However, for 5% lacuna, the magnetic behavior is close to the theoretical 3D-Heisemberg prediction with short-range exchange coupling.

Experience gained with the 3D machining of the W7-X HHF divertor target elements

International Nuclear Information System (INIS)

Junghanns, P.; Boscary, J.; Peacock, A.

2015-01-01

Highlights: • The Wendelstein 7-X surface of the actively cooled divertor is built up of 890 individually 3D machined target elements. • To date 300 target elements have been 3D machined with an accuracy of ±0.015 mm. • Copper discovered on the surface of few elements is no risk to operation. - Abstract: The high heat flux (HHF) divertor of W7-X consists of 100 target modules assembled from 890 actively water-cooled target elements protected with CFC tiles. The divertor surface will be built up of individually 3D machined target elements with 89 individual element types. To date 300 of the 890 target elements have been 3D machined with a very good accuracy. To achieve this successful result, a prototyping phase has been conducted to qualify the manufacturing route and to define the acceptance criteria with measures taken to minimize the risk of unacceptable damage during the manufacturing. After the 3D-machining, during the incoming inspection, copper infiltration from the interface between the CFC tiles and the CuCrZr heat sink to the plasma facing surface was detected in a small number of elements.

Review of the high heat flux testing as an integrated part of W7-X divertor development

International Nuclear Information System (INIS)

Greuner, H.; Boeswirth, B.; Boscary, J.; Friedrich, T.; Lavergne, C.; Linsmeier, Ch.; Schlosser, J.; Wiltner, A.

2009-01-01

The subject of the development of the WENDELSTEIN 7-X divertor is the manufacturing of approximately 900 plasma facing components (PFCs) that meet all requirements for reliable long pulse and long-term plasma operation. The actively cooled PFCs are made of CFC NB31 as plasma facing material bonded by Active Metal Casting (AMC) copper interlayer onto CuCrZr cooling structure. The pre-series activities integrated extensive high heat flux (HHF) testing to assess the industrial manufacturing. Tests were performed in the GLADIS facility under load conditions similar to those expected during operation of W7-X. The investigations focused on the improvement of fatigue resistance of the CFC/Cu bonding. The results of the last HHF test campaign demonstrated a significant enhancement of the CFC bonding quality due to the introduction of the AMC/Cu bi-layer technology. The results of the micro-chemical analyses (using EDX, AES, XPS and SIMS) of the CFC/Cu interface performed after 5000 cycles at 10 MW/m 2 confirmed its chemical stability. Far beyond the current available data about the expected lifetime of CFC-armoured PFCs, 10,000 cycles at 10 MW/m 2 were applied without any damages at the interface. The present design and manufacturing process of the tested PFCs fulfil all requirements for W7-X operation.

Magnetic properties of polycrystalline PrxY1-xBa2Cu3O7-δ

International Nuclear Information System (INIS)

Stari, C.; Rivera, V.A.G.; Lanfredi, A.J.C.; Cardoso, C.A.; Leite, E.R.; Mombru, A.W.; Araujo-Moreira, F.M.

2008-01-01

In this work, we report a part of a systematic study of the influence of the synthesis routes on the properties of polycrystalline samples of Pr x Y 1-x Ba 2 Cu 3 O 7-δ . We have prepared high-quality samples of this material by following a sol-gel method, associated with heat treatment in both an inert argon and an oxygen atmospheres in order to compare their influence on the formation of the superconducting phase. Magnetic measurement (AC susceptibility) show that the superconducting transition temperature (T C ) increases in samples prepared in argon when compared to those prepared in oxygen, for the same composition and Pr fraction less than 0.5. In addition to this, preliminary results of AC and DC magnetic susceptibility show superconductivity for samples with Pr fraction higher than 0.5 (and up to 0.9) prepared under argon flux, which may indicate the existence of stable superconductivity for all compositions, including pure Pr-123

Second order magnetic phase transition and scaling analysis in iron doped manganite La0.7Ca0.3Mn1−xFexO3 compounds

International Nuclear Information System (INIS)

Ginting, Dianta; Nanto, Dwi; Denny, Yus Rama; Tarigan, Kontan; Hadi, Syamsul; Ihsan, Mohammad; Rhyee, Jong-Soo

2015-01-01

We investigated magnetic properties of La 0.7 Ca 0.3 Mn 1−x Fe x O 3 (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La 0.7 Ca 0.3 Mn 1−x Fe x O 3 (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x<0.09) in previous reports. When we investigate the critical behavior of the compounds near T=T c by the modified Arrott plot, Kouvel–Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε −β M(H,ε) and renormalized field h=|ε| β+γ H. Temperature-dependent effective exponents β eff and γ eff correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration. - Highlights: • The ferromagnetic phase transition is of second order in La 0.7 Ca 0.3 Mn 1−x Fe x O 3 . • The critical exponents are in between the 3D Heisenberg and mean-field models. • The ferromagnetic interaction becomes more itinerant by Fe-doping

Crystal structure and magnetic state of pseudo-binary intermetallic compounds Ho(Cosub(1-x)Nisub(x))sub(5)

International Nuclear Information System (INIS)

Chuev, V.V.; Kelarev, V.V.; Pirogov, A.N.; Sidorov, S.K.; Koryakova, V.S.

1983-01-01

In the range of 1.8-1000 K intermetallic compounds Ho(Cosub(1-x)Nisub(x))sub(5) have been investigated neutronographically and roentgenographically. Crystal structure of two series of samples: HoCosub(5.5-5.5x)Nisub(5x) and HoCosub(5-5x)Nisub(5x) is studied. It is shown that Ni atoms mainly occupy positions 2c, Co atoms - positions 3g; coordinates of atoms and position occupation of TbCu 7 type structure are specified. Analysis of magnetic structure is made, angles of magnetic momenta orientation as to crystallographic axes are determined. Magnetic phase diagram is built. Concentrational dependences of sublattice magnetization: Msub(Ho)(x), Mdsub(2c)(x), Mdsub(3g)(x) are determined

Resistive ballooning modes in W7-AS and W7-X

International Nuclear Information System (INIS)

Kaiser, R.

1993-01-01

'Critical' pressure gradients due to resistive ballooning modes and their growth rates were computed for the W7-AS stellarator and for a HELIAS configuration with W7-X parameters, and the two configurations were compared. The results are based on the evaluation of a fourth order magnetic differential equation along closed magnetic field lines. The numerical procedure applying a variational approach uses the 'Garching resistive ballooning code', GARBO, which was originally developed for the stability analysis of axisymmetric plasmas. Concerning purely growing modes, this analysis shows that the favourable stability properties of W7-X, already optimized with respect to ideal ballooning modes, persist in the resistive regime: the destabilizing effect of resistivity is largely compensated by the stabilizing contribution of plasma compression. As a consequence, the ideal β limit continues only moderately shifted in the resistive case and likewise ideal ballooning stable equilibria (up to β 0 ≅ 5%) do not become resistively unstable. The situation is different for W7-AS. Greater resistive effects (in comparison with W7-X) are found in a configuration that is already ideally much more unstable. A basic feature in resistive calculations is the occurrence of overstable modes. These modes no longer show a stability threshold and, for realistic values of pressure and resistivity, linear instability is obtained for W7-AS as well as for W7-X, with growth rates and oscillation frequencies in the kilo-Hertz range. (author). 29 refs, 13 figs

Magnetic-field-induced irreversible antiferromagnetic–ferromagnetic phase transition around room temperature in as-cast Sm–Co based SmCo{sub 7−x}Si{sub x} alloys

Energy Technology Data Exchange (ETDEWEB)

Feng, D.Y.; Zhao, L.Z.; Liu, Z.W., E-mail: zwliu@scut.edu.cn

2016-04-15

A magnetic-field-induced irreversible metamagnetic phase transition from antiferro- to ferromagnetism, which leads to an anomalous initial-magnetization curve lying outside the magnetic hysteresis loop, is reported in arc-melted SmCo{sub 7−x}Si{sub x} alloys. The transition temperatures are near room temperature, much higher than other compounds with similar initial curves. Detailed investigation shows that this phenomenon is dependent on temperature, magnetic field and Si content and shows some interesting characteristics. It is suggested that varying interactions between the Sm and Co layers in the crystal are responsible for the formation of a metastable AFM structure, which induces the anomalous phenomenon in as-cast alloys. The random occupation of 3g sites by Si and Co atoms also has an effect on this phenomenon.

Highlights from e-EPS: Fusion experiment nears completion, nominations open for prize, and technology transfer group launched

CERN Multimedia

e-EPS News

2012-01-01

e-EPS News is a monthly addition to the CERN Bulletin line-up, showcasing articles from e-EPS – the European Physical Society newsletter – as part of a collaboration between the two publications.   Core of fusion experiment completed The last major part of the Wendelstein 7-X fusion experiment was installed on 21 December last year. The addition of the 14 tonne final part of the device – the lid of the thermally insulating outer shell – sees the completion of the ring-like base machine at the Greifswald branch of the Max Planck Institute of Plasma Physics, which will begin operation in 2014. Fusion research aims to draw energy from the fusion of atomic nuclei. To achieve this, hydrogen plasma must be superheated to temperatures above 100 million degrees, within the confines of a restricting magnetic field. The Wendelstein 7-X – which will be the largest fusion device of its type – will investigate the feasibility of such a power pl...

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

Science.gov (United States)

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

2018-03-01

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

Magnetic and transport properties of EuNi(Si1-xGex)3 compounds

International Nuclear Information System (INIS)

Uchima, K; Takaesu, Y; Akamine, H; Kakihana, M; Tomori, K; Uejo, T; Teruya, A; Nakamura, A; Hedo, M; Nakama, T; Yagasaki, K; Matsubayashi, K; Uwatoko, Y

2014-01-01

The magnetization M, electrical resistivity ρ, thermopower S and specific heat C of EuNi(Si 1-x Ge x ) 3 compounds have been measured at temperatures from 2 to 300 K. For the compounds of EuNi(Si 1-x Ge x ) 3 , we obtained an effective magnetic moment of μ eff ∼ 7.7 μ B , which is close to the divalent Eu value of μ eff =7.94 μ B . All compounds of EuNi(Si 1-x Ge x ) 3 order antiferromagnetically. The Néel temperature T N decreases monotonously with increasing the Ge concentration x from T N =49 K for EuNiSi 3 to T N =14 K for EuNiGe 3 . In the low temperature region below T N , anomalies corresponding to an additional magnetic phase transition into ferromagnetic state for compounds with x < 0.3, and into another antiferromagnetic for x > 0.3 were observed. The Curie temperature T C rapidly decreases with increasing x and vanishes at x ≈ 0.3. It is found that the magnetic phase transition temperatures of T N and T C in EuNi(Si 1-x Ge x ) 3 are strongly connected with the change of volume induced by the atomic substitution of Si by Ge

Doping-induced quantum crossover in Er2Ti2 -xSnxO7

Science.gov (United States)

Shirai, M.; Freitas, R. S.; Lago, J.; Bramwell, S. T.; Ritter, C.; Živković, I.

2017-11-01

We present the results of the investigation of magnetic properties of the Er2Ti2 -xSnxO7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x =0 parent compound. Around x =1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er2Sn2O7 (x =2.0 ) below TN=130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x =0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x =1.7 .

Effect of grain boundary layer strain on the magnetic and transport properties of (100-x) La0.7Ca0.3MnO3/(x) BaTiO3 composites showing enhanced magnetoresistance

International Nuclear Information System (INIS)

Bose, Esa; Taran, S.; Karmakar, S.; Chaudhuri, B.K.; Pal, S.; Sun, C.P.; Yang, H.D.

2007-01-01

A ferromagnetic/ferroelectric composite system, viz. (100-x)La 0.7 Ca 0.3 MnO 3 [LCMO]/(x) BaTiO 3 [BTO] (with x=0.0%, 1.0%, 5.0%, 7.5%, 10.0% and 15.0%, in wt%) has been synthesized and the temperature-dependent DC magnetization M(T), resistivity ρ(T), magnetoresistance (MR), and thermoelectric power S(T) have been studied. Both metal-insulator transition temperature (T MI ) and the corresponding Curie temperature (T C ) decrease whereas peak resistivity at T MI increases as x is enhanced from 0.0% to 10.0%. For x>10.0%, this trend of variation is reversed. A maximum three-fold increase of magnetoresistance (MR) is observed (for sample with x=10.0%) due to the addition of ferroelectric (non-magnetic) perovskite BTO (compared to the mother compound LCMO). Interestingly, thermoelectric power S(T) shows a pronounced depression (dip) near the magnetic transition region for the composite samples. The above results have been analyzed considering strain induced by the LCMO/BTO grain boundary layer (BL)

ECRH and W7-X: An intriguing pair

Science.gov (United States)

Erckmann, V.; Braune, H.; Gantenbein, G.; Jelonnek, J.; Kasparek, W.; Laqua, H. P.; Lechte, C.; Marushchenko, N. B.; Michel, G.; Plaum, B.; Thumm, M.; Weissgerber, M.; Wolf, R.; W7-X ECRH Teams

2014-02-01

The construction of the W7-X basic machine is almost completed and the device is approaching the commissioning phase. W7-X operation will be supported by ECRH working at 140 GHz in 2nd harmonic X- or O-mode with 10 MW cw power. Presently the activities at W7-X concentrate on the implementation of wall-armour, in-vessel components and diagnostics. The ECRH-system is in stand by with 5 out of 10 gyrotrons operational. The status of both, the W7-X device and the ECRH system is reported. Further R&D activities concentrate on extending the launching capability for sophisticated confinement investigations with remote steering launchers in a poloidal plane with weak magnetic field gradient.

X-rays and magnetism

International Nuclear Information System (INIS)

Fischer, Peter; Ohldag, Hendrik

2015-01-01

Magnetism is among the most active and attractive areas in modern solid state physics because of intriguing phenomena interesting to fundamental research and a manifold of technological applications. State-of-the-art synthesis of advanced magnetic materials, e.g. in hybrid structures paves the way to new functionalities. To characterize modern magnetic materials and the associated magnetic phenomena, polarized x-rays have emerged as unique probes due to their specific interaction with magnetic materials. A large variety of spectroscopic and microscopic techniques have been developed to quantify in an element, valence and site-sensitive way properties of ferro-, ferri-, and antiferromagnetic systems, such as spin and orbital moments, and to image nanoscale spin textures and their dynamics with sub-ns time and almost 10 nm spatial resolution. The enormous intensity of x-rays and their degree of coherence at next generation x-ray facilities will open the fsec time window to magnetic studies addressing fundamental time scales in magnetism with nanometer spatial resolution. This review will give an introduction into contemporary topics of nanoscale magnetic materials and provide an overview of analytical spectroscopy and microscopy tools based on x-ray dichroism effects. Selected examples of current research will demonstrate the potential and future directions of these techniques. (report on progress)

Mn doping effect on structure and magnetism of epitaxial (FePt)1-xMnx films

International Nuclear Information System (INIS)

Huang, J.C.A.; Chang, Y.C.; Yu, C.C.; Yao, Y.D.; Hu, Y.M.; Fu, C.M.

2003-01-01

We study the structure and perpendicular magnetism of molecular beam epitaxy grown (FePt) 1-x Mn x films with doping concentration x=0, 1%, 2%, 3%, 4%, and 5%. The (FePt) 1-x Mn x films were made by multilayers growth of [Fe/Pt/Mn]xN at 100 deg. C and annealed at 600 deg. C. X-ray diffraction scans indicate that relatively better L1 0 ordered structure for low Mn doping (x 3%. The perpendicular magnetic anisotropy effect of the (FePt) 1-x Mn x films tends to decrease with the increase of Mn doping for x>1%. However, the x=1% doped films possess slightly better perpendicular magnetic anisotropy effect than the zero doped film. The perpendicular magnetic anisotropy constant are of about 1.3x10 7 and 1.6x10 7 erg/cm 3 for x=0% and x=1%, respectively

Magnetic and magnetoelastic properties of the random anisotropy amorphous magnets Tb2(FexNi1-x)

International Nuclear Information System (INIS)

De la Fuente, C.; Arnaudas, J.I.; Del Moral, A.; Ciria, M.

1996-01-01

Amorphous Tb 2 (Fe x Ni 1-x ) compounds show the strongest random anisotropy known: D/J≅5.2, between crystal field and exchange strengths, separately obtained. The magnetic phase diagram shows two speri-magnetic phases. The effective magnetic moment is reduced, μ eff. (5 K, 12 T)≅7.2 μ B /Tb 3+ . Magnetostriction is very large and constant, λ t (5 K, 12 T)≅4.1.10 -3 . The local distribution of Tb 3+ ions is aspherical. (orig.)

Characterization of the island divertor plasma of W7-AS stellarator in the deeply detached state with volume recombination

International Nuclear Information System (INIS)

Ramasubramanian, N.; Koenig, R.; Feng, Y.; Giannone, L.; Grigull, P.; Klinger, T.; McCormick, K.; Thomsen, H.; Wenzel, U.

2004-01-01

In the high-density H-mode of the Stellarator Wendelstein 7-AS, the plasma detaches from the island divertor targets when the line-averaged density exceeds a critical value. This quasi-stationary detachment is found to be partial and shows edge-localized, poloidally asymmetric radiation. The spectroscopic characteristics of the deeply detached plasma are reported, including evidence for volume recombination. The detached plasma radiates up to 90% of the absorbed power with larger contributions from the locations close to magnetic X-points outside the divertor region. The spectral analysis of the Balmer series indicate very high densities and low temperatures at the detached regions. The results of the spectral analysis underline the importance of three-dimensional modelling. An initial comparison is made with the latest results from EMC3-EIRENE modelling. (author)

Magnetism and large magnetocaloric effect in HoFe{sub 2-x}Al{sub x}

Energy Technology Data Exchange (ETDEWEB)

Mican, S., E-mail: sever.mican@ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania); Benea, D., E-mail: diana.benea@phys.ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania); Tetean, R., E-mail: romulus.tetean@phys.ubbcluj.ro [Babes-Bolyai University Cluj-Napoca, RO-400084 Cluj-Napoca (Romania)

2013-02-05

Highlights: Black-Right-Pointing-Pointer Structural, magnetic and magnetocaloric properties of HoFe{sub 2-x}Al{sub x} compounds are reported. Black-Right-Pointing-Pointer Electronic structure calculations show a good agreement between theory and experiment. Black-Right-Pointing-Pointer Magnetic transitions close to room temperature for the Fe-rich samples. Black-Right-Pointing-Pointer High values of the relative cooling power for all of the investigated samples. Black-Right-Pointing-Pointer No hysteresis losses in applied fields of up to 4 T. - Abstract: The structural, magnetic and magnetocaloric properties of several HoFe{sub 2-x}Al{sub x} compounds were investigated. The compounds in the Fe-rich region (0.36 Less-Than-Or-Slanted-Equal-To x Less-Than-Or-Slanted-Equal-To 0.4) crystallize in the cubic MgCu{sub 2} (C15) structure, while for the ones in the intermediate region (0.75 Less-Than-Or-Slanted-Equal-To x Less-Than-Or-Slanted-Equal-To 1.125) the hexagonal MgZn{sub 2} (C14) structure was observed. Electronic structure calculations were performed, showing a good agreement between theory and experiment. The Curie temperatures were found to decrease with Al content. For the Fe-rich compounds, these are close to room temperature, while for the compounds in the intermediate region, transition temperatures are well below 300 K. No magnetic hysteresis was found around the Curie temperature for applied magnetic fields of up to 4 T. All of the investigated compounds undergo a second-order magnetic phase transition at the Curie temperature. A maximum magnetic entropy change value of 7.6 J/kg K was obtained for the sample with x = 1.125, all of the samples displaying rather large RCP values. The possibility of incorporating these materials in magnetic refrigeration devices is discussed.

Effect of doping with magnetic 3D-elements on the thermal fluctuations and critical parameters of CaLaBaCu{sub 3-x}(Ni,Co){sub x}O{sub 7-{delta}} superconductors

Energy Technology Data Exchange (ETDEWEB)

Rojas Sarmiento, M.P.; Landinez Tellez, D.A. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia); Roa-Rojas, J. [Grupo de Fisica de Nuevos Materiales, Departamento de Fisica, Universidad Nacional de Colombia, AA 14490, Bogota DC (Colombia)], E-mail: jroar@unal.edu.co

2008-07-15

Systematic measurements on conductivity fluctuation in the CaLaBaCu{sub 3-x}(Ni,Co){sub x}O{sub 7-{delta}} system are reported. Samples with x=0, 0.03, 0.06, 0.09, 0.12, 0.15 and 0.18 were prepared by the standard solid-state reaction recipe. Results of resistivity measurements reveal a linear-like decreasing of the critical temperature T{sub c} with progressive substitution of magnetic elements Ni and Co into the Cu crystallographic sites. From the fluctuation analysis, above and close to T{sub c}, we found the occurrence of three- and two-dimensional Gaussian fluctuation regimes. Closer to T{sub c}, a genuinely critical regime is observed. On the Ginzburg-Landau formalism, from the reduced temperature of the three-dimensional Gaussian region and the mean field critical temperature, we have experimentally obtained the Ginzburg number for the CaLaBaCu{sub 3-x}(Ni,Co){sub x}O{sub 7-{delta}} material. Then, critical magnetic field, critical current density and the jump in the specific heat at the critical temperature are calculated. Critical parameters are strongly affected by the doping with magnetic ions.

Structure and magnetic properties of Gd{sub x}Y{sub 1−x}FeO{sub 3} obtained by mechanosynthesis

Energy Technology Data Exchange (ETDEWEB)

Bolarín-Miró, A.M. [Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo Mineral de la Reforma, Hidalgo 42184 (Mexico); Sánchez-De Jesús, F., E-mail: fsanchez@uaeh.edu.mx [Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo Mineral de la Reforma, Hidalgo 42184 (Mexico); Cortés-Escobedo, C.A. [Centro de Investigación e Innovación Tecnológica del IPN, Distrito Federal 02250 (Mexico); Valenzuela, R. [Depto. de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Ammar, S. [ITODYS, UMR 7086, Université de Paris-Diderot, 75250 Paris Cedex (France)

2014-02-15

Highlights: • Orthohombic GDxY1-xFeO3 was obtained by mechanosynthesis after 5 h of milling. • Mechanosynthesized GdxY1-xFeO3 show weak ferromagnetic behavior. • Mechanosynthesis promotes unexpected magnetic properties in GdxY1-xFeO3. • The maximum magnetization that was reached 7.7 emu/g for Gdo.75Y0.25FeO3. • For Gd0.5Y0.5FeO3, the magnetization decreases down to 2.1 emu/g. -- Abstract: Solid solutions of yttrium–gadolinium orthoferrites Gd{sub x}Y{sub 1−x}FeO{sub 3} (0 ⩽ x ⩽ 1) were prepared by high-energy ball milling. The aim of this work was to study the influence of the synthesis parameters on the crystal structure and the magnetic behavior of these solid solutions. The precursors, Fe{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}, mixed in a stoichiometric ratio to obtain these orthoferrites, were milled for different times (up to 5 h). X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the milling time. Results showed the complete formation of orthoferrite with an orthorhombic structure (S.G. Pbnm) without any annealing after 5 h of milling for all of the compositions. The effect of the synthesis process and the x value on the crystal structure and the magnetic properties were also studied. All of the synthesized powders demonstrated weak ferromagnetic behavior. In particular, an increase in the maximum magnetization for all the compositions was found, with a maximum that reached 7.7 emu/g for Gd{sub 0.75}Y{sub 0.25}FeO{sub 3}. For Gd{sub 0.5}Y{sub 0.5}FeO{sub 3}, the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments.

The WEGA Stellarator: Results and Prospects

International Nuclear Information System (INIS)

Otte, M.; Andruczyk, D.; Koenig, R.; Laqua, H. P.; Lischtschenko, O.; Marsen, S.; Schacht, J.; Podoba, Y. Y.; Wagner, F.; Warr, G. B.; Holzhauer, E.; Howard, J.; Krupnik, L.; Zhezhera, A.; Urban, J.; Preinhalter, J.

2008-01-01

In this article an overview is given on results from magnetic flux surface measurements, applied ECR heating scenarios for 2.45 GHz and 28 GHz, fluctuation and transport studies and plasma edge biasing experiments performed in the WEGA stellarator. Examples for the development of new diagnostics and the machine control system are given that will be used at Wendelstein 7-X stellarator, which is currently under construction in Greifswald

Influence of oxygen disordering on static magnetic susceptibility of YBa2Cu3O7-x ceramics

International Nuclear Information System (INIS)

Sokolov, B.Yu.; Vil'danov, R.R.

2008-01-01

Influence of disordering of the populated oxygen positions in YBa 2 Cu 3 O 7-x ceramic's structure on its static magnetic susceptibility in the range of temperatures T>Tc is investigated. For occurrence of disordering the initial ceramics YBa 2 Cu 3 O 6,9 was annealed at T=520 C with the subsequent quenching in liquid nitrogen. Evolutions of a magnetic susceptibility and resistance of annealed ceramics during its air storage at a room temperature were studied. It is revealed that, unlike the initial optimum doped ceramics, annealed samples have appreciable temperature dependence of a magnetic susceptibility. Interpretation of results is executed on the basis of model of electronic phase separation and occurrence of a pseudo gap in a energy spectrum of free carriers of a superconductor. (authors)

Experimental verification of the axial and lateral stiffness of large W7-X rectangular bellows

International Nuclear Information System (INIS)

Reich, J.; Cardella, A.; Koppe, T.; Missal, B.; Capriccioli, A.; Loehrer, W.; Langone, S.; Sassone, P.C.

2006-01-01

The WENDELSTEIN 7-X (W7-X) is a super-conducting helical advanced stellarator. W7-X is provided with 299 ports, which connect the plasma vessel with the outer vessel. All the ports are equipped with bellows, which, during bake-out and final adjustment, compensate the relative movements of the vessels. The bellows have different shapes and dimensions ranging from 100 mm circular to 1170 x 570 mm rectangular sizes. During various load-cases the axial and lateral stiffness of all bellows will create a resulting spring-force which acts on the supports of the vessels directly. The higher the stiffness the more is the significant influence on the supports. The lateral stiffness which was calculated with the established standard EJMA-code (Expansion Joint Manufacturers Association) seemed to be relatively small. This appeared to be not correct in particular for non circular bellows. That is why the stiffness of rectangular, multi-layer bellows have then been re-calculated with the Finite Element Method (FEM) code ANSYS. The maximum difference between the FEM and EJMA code resulted to be up to 250 % in particular with movements along the longer side of the bellows. In order to clarify the differences a test-campaign with the largest rectangular bellows was performed. A special test rack allowed predefined displacements in pure lateral and axial directions taking into consideration of the friction in the moving elements. During the tests the load-displacement diagram was recorded permanently. The outcome of the FEM-results was then verified by the tests in axial and lateral directions. The EJMA-code is well proved for circular bellows. The tests showed that instead any calculation of rectangular bellows has to be confirmed by experiments. The paper summarises the calculation, describes the test activities, the apparatus and reports the final results. (author)

Cyclic heat load testing of improved CFC/Cu bonding for the W 7-X divertor targets

International Nuclear Information System (INIS)

Greuner, H.; Boeswirth, B.; Boscary, J.; Chaudhuri, P.; Schlosser, J.; Friedrich, T.; Plankensteiner, A.; Tivey, R.

2009-01-01

Extensive high heat flux cycling testing of pre-series targets was performed in the neutral beam facility GLADIS to establish the industrial process for the manufacturing of 890 targets, which will be needed for the installation of the WENDELSTEIN 7-X divertor. The targets are manufactured of flat tiles of CFC NB31 as plasma facing material bonded by an Active Metal Casting copper interlayer onto a water-cooled CuCrZr structure. Based on the results of the 3D thermo-mechanical FEM analysis of the CFC/Cu interface, an additional set of 17 full-scale pre-series elements including three design variations was manufactured by PLANSEE SE. The insertion of an additional plastically compliant copper interlayer between the cooling structure and the Active Metal Casting interlayer showed the best results. No critical tile detachment was observed during >5000 cycles at 10 MW/m 2 . These results demonstrated the sufficient life time of the component for the expected heat load in operation.

Magnetic field effect on the electrical resistivity of Y1-xNixBa2Cu3O7-δ superconductor

Science.gov (United States)

Hadi-Sichani, Behnaz; Shakeripour, Hamideh; Salamati, Hadi

2018-06-01

The Ni- substituted Y1-xNixBa2Cu3O7-δ high temperature superconducting samples with 0 ≤ x zero to 1 Tesla, applied perpendicular to the current direction. To study of magnetoresistance is one of the most important ways to investigate the intergranular nature of superconducting materials. The resistive transition is made of two parts. The first- unaffected to applied magnetic field part which is near the onset of superconductivity. This region is due to superconductivity in grains. The second- broaden tail part which is due to the connectivity of the grains. At temperatures close to Tc 0, (ρ = 0), under applied magnetic fields, weak links are affected and the vortices are penetrated and move inside the intergranular and then the tail part is broaden. This broadening part observed in the electrical resistivity, ρ(T), and in the derivative of the electrical resistivity, dρ/dT, becomes too small or even absent in Ni doped samples. For pure sample, Tc 0 was around 90 K; by applying a magnetic field H = 0.3 T it shifted to 40 K. This broadening is 91.4 K to 80 K for x = 0.002 and 91.7 K to 85 K for x = 0.004 samples. We found an optimal value of Ni doping concentration which improves the coupling of the grains. Then, vortices get strongly pinned. These observations suggest that the Ni substitution can reduce the weak links and increase the Jc values of these superconductors.

Crystal and magnetic structure of the Ca3Mn2O7 Ruddlesden-Popper phase: neutron and synchrotron x-ray diffraction study

International Nuclear Information System (INIS)

Lobanov, Maxim V; Greenblatt, Martha; Caspi, El'ad N; Jorgensen, James D; Sheptyakov, Denis V; Toby, Brian H; Botez, Cristian E; Stephens, Peter W

2004-01-01

The crystallographic and magnetic structures of Ca 3 Mn 2 O 7 Ruddlesden-Popper phase have been determined by a combination of neutron and synchrotron x-ray diffraction. Two-phase behaviour observed at room temperature is attributed to an incomplete structural phase transition. The magnetic structure was solved in the Cm'c2 1 ' Shubnikov group with dominant G-type antiferromagnetic order in the perovskite bilayers. The temperature evolution of the structural and magnetic parameters is presented

Interplay between structure and magnetism in HoxPr1-x alloys. 2. Resonant x-ray magnetic scattering

DEFF Research Database (Denmark)

Vigliante, A.; Christensen, M.J.; Hill, J.P.

1998-01-01

X-ray-scattering techniques have been used to study the crystal and magnetic structures of HoxPr1-x alloys in the form of thin films. Three distinct crystal structures are found as a function of concentration x, each of which has a characteristic magnetic structure. For x greater than or equal to 0.......6 a hexagonal-close-packed phase is found with the magnetic moments ordered in a basal-plane helix, whereas for 0.4 less than or equal to x... hexagonal-close-packed and remain nonmagnetic down to the lowest temperatures studied. Using x-ray magnetic resonance scattering techniques, we demonstrate that a small, static spin-density wave is induced within the alloy 5d band at both the Pr and Ho sites in both of the magnetically ordered phases...

Behavior of the magnetocaloric effect in La0.7Ba0.2Ca0.1Mn1-xSnxO3 manganite oxides as promising candidates for magnetic refrigeration

Science.gov (United States)

Dhahri, Ja.; Mnefgui, Safa; Ben Hassine, A.; Tahri, Ta.; Oumezzine, M.; Hlil, E. K.

2018-05-01

The magnetocaloric effect along with magnetic phase transition in the peroveskite polycrystalline samples La0.7Ba0.2Ca0.1Mn1-xSnxO3 (x = 0 and 0.1) was investigated. The samples were synthesized using conventional solid state reaction at 1400 °C temperature. Magnetization vs. temperature measurements, under a magnetic field of μ0H = 0.05 T, showed a paramagnetic-ferromagnetic transition at Curie temperature, TC, which decreases from 310 K for x = 0-290 K for x = 0.1. A large magnetic entropy change | ΔSM | deduced from isothermal magnetization curves, has been observed in our samples with a peak centered on their respective TC. Interesting values of the relative cooling power (RCP), 237 J kg-1 for x = 0 and 248 J kg-1 x = 0.1, make these samples promising candidates for magnetic refrigeration around room temperature.

W7-AS/W7-X contributions to the 20th European conference on controlled fusion and plasma heating

International Nuclear Information System (INIS)

1993-08-01

This report contains the 23 contributions of the Max-Planck-Institut fuer Plasmaphysik to the above mentioned conference. The contributions deal with plasma heating problems in the Wendelstein stellarators. (WL)

Enhanced magnetization in morphologically and magnetically distinct BiFeO3 and La0.7Sr0.3MnO3 composites

Science.gov (United States)

Pillai, Shreeja; Reshi, Hilal Ahmad; Bagwaiya, Toshi; Banerjee, Alok; Shelke, Vilas

2017-09-01

Nanomaterials exhibit properties different from those of their bulk counterparts. The modified magnetic characteristics of manganite nanoparticles were exploited to improve magnetization in multiferroic BiFeO3 compound. We studied the composite of two morphologically and magnetically distinct compounds BiFeO3 (BFO) and La0.7Sr0.3MnO3 (LSMO). The microcrystalline BiFeO3 sample was prepared by solid state reaction method and the nanocrystalline La0.7Sr0.3MnO3 by sol-gel method. Composites with nominal compositions (1-x)BiFeO3-(x)La0.7Sr0.3MnO3 were prepared by modified solid state reaction method. The phase purity and crystal structures were checked by using X-ray diffraction. The formation of composites with phase separated BFO and LSMO was confirmed using Raman and Fourier Transform Infrared spectroscopy studies. The composite samples showed relatively high value of magnetization with finite coercivity. This improvement in magnetic behavior is ascribed to the coexistence of multiple magnetic orderings in composite samples. We scrutinized the possibility of oxygen vacancy or Fe mixed valency formation in the samples using X-ray photoelectron spectroscopy technique.

Magnetic properties and structure of (FexCo100-x)3Pt alloy thin films

International Nuclear Information System (INIS)

Nahid, M.A.I.; Suzuki, Takao

2005-01-01

A study of the magnetic properties of (Fe x Co 100-x ) 3 Pt (0= 19 ) phase is realized. This m-DO 19 phase is found to exhibit the large perpendicular magnetic anisotropy (K per ) (∼10 7 erg/cc). There is a maximum in K per at about x=10. The K per is found to decrease with x (x>10), which is correlated with the structural transformation

Modelling and analysis of flux surface mapping experiments on W7-X

Science.gov (United States)

Lazerson, Samuel; Otte, Matthias; Bozhenkov, Sergey; Sunn Pedersen, Thomas; Bräuer, Torsten; Gates, David; Neilson, Hutch; W7-X Team

2015-11-01

The measurement and compensation of error fields in W7-X will be key to the device achieving high beta steady state operations. Flux surface mapping utilizes the vacuum magnetic flux surfaces, a feature unique to stellarators and heliotrons, to allow direct measurement of magnetic topology, and thereby allows a highly accurate determination of remnant magnetic field errors. As will be reported separately at this meeting, the first measurements confirming the existence of nested flux surfaces in W7-X have been made. In this presentation, a synthetic diagnostic for the flux surface mapping diagnostic is presented. It utilizes Poincaré traces to construct an image of the flux surface consistent with the measured camera geometry, fluorescent rod sweep plane, and emitter beam position. Forward modeling of the high-iota configuration will be presented demonstrating an ability to measure the intrinsic error field using the U.S. supplied trim coil system on W7-X, and a first experimental assessment of error fields in W7-X will be presented. This work has been authored by Princeton University under Contract Number DE-AC02-09CH11466 with the US Department of Energy.

Testing of improved CFC/Cu bondings for the W7-X divertor targets

International Nuclear Information System (INIS)

Greuner, H.; Buswirth, B.; Boscary, J.; Tivey, R.; Plankensteiner, A.; Schedler, B.

2007-01-01

Full text of publication follows: Extensive high heat flux (HHF) testing of pre-series divertor targets was performed to establish the industrial process for the manufacturing of 890 targets, which will be needed for the installation of the Wendelstein 7-X (W7-X) divertor. The target design consists of flat tiles of CFC NB31 as plasma facing material bonded by an Active Meta] Casting copper (AMC) interlayer onto a water-cooled CuCrZr structure. This design is required by the specific geometrical requirements of the W7-X divertor. The heat removal capability of this target concept has been demonstrated for the envisaged operational power load of 10 MW/m 2 in previous test series of more than 30 full-scale elements. No large detachment or loss of CFC tiles occurred during cyclic loading tests at 10.5 and 13 MW/m 2 , but growing local de-bonded zones at the free edges of several CFC tiles were observed. Therefore a detailed analysis of the system of CFC/Cu bonding was carried out with respect to a further reduction of the stress at the CFC/Cu interface. Based on the results of the 3/D non-linear thermomechanical FEM analysis of the CFC/Cu interface a set of 17 additional pre-series elements was manufactured by PLANSEE SE. Three types of design variations have been investigated: - adopting an additional plastically compliant Cu interlayer between the cooling structure and the AMC region, - reduced size of CFC tiles, - arrangement of tiles with 90 deg. rotation of the CFC fibre plane. HHF tests were performed in the ion beam test facility GLADIS at IPP Garching with up to 3000 cycles at 10.5 MW/m 2 on this elements. The aim of these tests is to investigate the crack propagation between CFC/Cu and to define the acceptable defect size after 100 HHF cycles as an acceptance criterion for the series manufacturing. The applied criterion should allow the selection of elements for W7-X expected to achieve a suitable operational life time. Finally, the design variant with the

Neutron flux measurements at the Wendelstein VII-A stellarator

International Nuclear Information System (INIS)

Weller, A.; Maassberg, H.

1985-10-01

In addition to charge exchange analysis (CX) and charge exchange recombination spectroscopy (CXRS), the time evolution of the central ion temperature during neutral beam heated plasma discharges in the Wendelstein VII-A stellarator is derived from the neutron flux from thermal D-D reactions. In general, good quantitative agreement between the different methods is obtained. Neutron flux measurements also permit to investigate the slowing down of fast D + -ions from neutral beam injection (NBI). The results agree well with the predictions based on the assumption of a collisional slowing down mechanism. (orig.)

Comparative studies to the design of the interferometer at W7-X with respect to technical boundary conditions

International Nuclear Information System (INIS)

Dreier, H.; Dinklage, A.; Hirsch, M.; Kornejew, P.; Fischer, R.

2008-01-01

For the optimisation of the beam line configuration of the multi-channel interferometer at the Wendelstein 7-X stellarator the probabilistic approach of Bayesian experimental design (BED) is applied. Parameters of physical interest are directly implemented as design criteria. The quality of the design is analysed according to its expected information gain (expected utility) about the parameters of interest, which enables one to compare different diagnostic configurations quantitatively. The focus of this work lies on the comparison of different technical approaches for the interferometer diagnostic. Different physical problems (high confinement regimes, neoclassical predictions) and their effect on the density distribution are applied as optimisation goals. The influence of the port system and the in-vessel components (retro-reflectors) is discussed. For this, the design was done with and without technical restrictions, the resulting expected utilities are compared and analysed. Furthermore, the impact of an additional beamline at a different toroidal position (congruent to the Thomson scattering diagnostic) is examined

Transverse- and zero-field μSR [muon-spin-rotation] investigation of magnetism and superconductivity in (Y1-xPrx)Ba2Cu3O7

International Nuclear Information System (INIS)

Cooke, D.W.; Jahan, M.S.; Kwok, R.S.; Lichti, R.L.; Adams, T.R.; Boekema, C.; Dawson, W.K.; Kebede, A.; Schwegler, J.; Crow, J.E.; Mihalsin, T.

1990-01-01

Zero-field muon-spin-rotation (μSR) measurements on (Y 1-x Pr x )Ba 2 Cu 3 O 7 [x = 1.0, 0.8, 0.6, and 0.54] show evidence for antiferromagnetic ordering of the Cu moments within the Cu--O planes, with Neel temperatures 285,220, 35, 30, and 20 K respectively. For x = 1.0 the local muon magnetic field is ∼16 mT, but decreases to ∼12 mT at 17 K, due to additional magnetic ordering. The zero-field data, in conjunction with transport data, allow construction of a complete diagram for this system. Transverse-field (1 kOe) μSR data for x = 0.2 (T c = 75 K) show that the muon depolarization is determined primarily by the Cu nuclear moments for T>T c . Fitting the superconducting-state data to a BCS model yields an extrapolated zero-temperature magnetic penetration depth of 2170 angstrom. 9 refs., 3 figs

Magnetic X-Ray Scattering with Synchrotron Radiation

DEFF Research Database (Denmark)

Moncton, D. E.; Gibbs, D.; Bohr, Jakob

1986-01-01

With the availability of high-brilliance synchrotron radiation from multiple wigglers, magnetic X-ray scattering has become a powerful new probe of magnetic structure and phase transitions. Similar to the well-established magnetic neutron scattering technique, magnetic X-ray scattering methods have...... many complementary advantages. A brief review is presented of the history of magnetic X-ray scattering as well as recent results obtained in studies of the rare-earth magnet holmium with emphasis on instrumentational aspects. In particular, the development of a simple polarization analyzer...... to distinguish charge and magnetic scattering is described....

Review of the acceptance tests of the W7-X superconducting magnets

International Nuclear Information System (INIS)

Ehmler, H.; Baldzuhn, J.; Genini, L.; Heyn, K.; Sborchia, C.; Schild, T.

2007-01-01

The W7-X magnet system consists of 50 non-planar coils of five different types and 20 planar coils of two different types. Factory tests of the non-planar coils are carried out at the manufacturer site of Babcock-Noell, Germany, and for the planar coils at Tesla Engineering, UK. They consist of electrical insulation checks, mass flow measurements, leak tests and sensor checks. In the test facility of CEA Saclay, France, each coil is cooled down to ∼5 K and operated at nominal current. At least one coil of each type is quenched by increasing the inlet temperature. Results of the mass flow measurements and the quench tests are presented. The manufacturing and testing progress is reviewed and the impact of technical failures is discussed. In conclusion, the scope of the tests allows a very strict quality control. This experience is highly beneficial for the construction and testing of similar components for future superconducting fusion experiments

Magnetic behavior of the alloys (Ce{sub 1-x}Y{sub x}){sub 2}PdSi{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mallik, R [Tata Inst. of Fundamental Res., Colaba, Mumbai (India); Sampathkumaran, E V [Tata Inst. of Fundamental Res., Colaba, Mumbai (India)

1996-11-01

The results of X-ray diffraction (Cu K{sub {alpha}}), electrical resistivity ({rho}), heat capacity (C) and magnetic susceptibility ({chi}) measurements are reported for a new pseudoternary solid solution, (Ce{sub 1-x}Y{sub x}){sub 2}PdSi{sub 3} (x=0.0, 0.2, 0.5, 0.8, 1.0). The X-ray diffraction patterns indicate that single phase alloys can be formed in a derived version of the AlB{sub 2}-type hexagonal structure for x{>=}0.2, while for x=0.0, apparently there is an additional weak phase. In the case of the alloy Ce{sub 2}PdSi{sub 3}, the majority of Ce ions do not exhibit magnetic ordering down to 1.4 K, though magnetic ordering at 7 K from one of the two crystallographically inequivalent sites cannot be ruled out. For other compositions, no magnetic ordering is observed above 1.4 K. The Kondo effect is operative in all these alloys, with the strength of the Kondo effect increasing with the compression of the lattice by the gradual replacement of Ce by Y. The C/T exhibits a low temperature enhancement in all Ce containing alloys. (orig.).

Magnetic interactions in praseodymium ruthenate Pr{sub 3}RuO{sub 7} with fluorite-related structure

Energy Technology Data Exchange (ETDEWEB)

Inabayashi, Masaki; Doi, Yoshihiro; Wakeshima, Makoto; Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.jp

2017-06-15

Solid solutions Pr{sub 3}(Ru{sub 1-x}Ta{sub x})O{sub 7} (0≤x≤1.0) and (Pr{sub 1-x}Y{sub x}){sub 3}RuO{sub 7} (0≤x≤0.7) were obtained as a single phase compound. They crystallize in an orthorhombic superstructure derived from that of the cubic fluorite with space group Cmcm. The results of the Rietveld analysis for X-ray diffraction profiles of Pr{sub 3}(Ru{sub 1-x}Ta{sub x})O{sub 7} showed that Ru and Ta atoms are randomly situated at the six-coordinate 4b site. For (Pr{sub 1-x}Y{sub x}){sub 3}RuO{sub 7}, with increasing the concentration of Y ions (x value), the smaller Y ions occupy selectively the seven-coordinate 8g site rather than the eight-coordinate 4a site. Through magnetic susceptibility measurements for Pr{sub 3}(Ru{sub 1-x}Ta{sub x})O{sub 7}, the antiferromagnetic transition temperatures decrease linearly with increasing x value, and at x=0.75 no magnetic ordering was found down to 1.8 K, indicating the magnetic interaction is not one-dimensional, but three-dimensional. On the other hand, the antiferromagnetic transition temperature for (Pr{sub 1-x}Y{sub x}){sub 3}RuO{sub 7} decreases with increasing x value, but above x≥0.50 it becomes constant (~12 K). This result indicates that Pr{sup 3+} ions at the seven-coordinate site greatly contribute to the antiferromagnetic interactions observed in (Pr{sub 1-x}Y{sub x}){sub 3}RuO{sub 7}. Density functional calculations of Pr{sub 3}RuO{sub 7} demonstrate that the electronic structure gives insulating character and that oxygen 2p orbitals hybridize strongly with Ru 4d orbitals in the valence band (VB). Near the top of VB, the Pr 4 f orbitals at the seven-coordinated site also show a weak hybridization with the O(1) 2p orbitals. The Ru-O(1)-Pr superexchange pathway take part in three-dimensional magnetic interaction and play an important role in an enhancement of long-range magnetic ordering. - Graphical abstract: The spin densities and the spin polarization of Pr{sub 3}RuO{sub 7} are shown

Magnetic resonance imaging of the central nervous system. Comparison with X-ray CT

Energy Technology Data Exchange (ETDEWEB)

Kajima, Toshio; Kagawa, Yoshihiro; Katsuta, Shizutomo.

1987-06-01

Magnetic resonance imaging (MRI) and X-ray computed tomography (X-ray CT) have been performed in 169 consecutive patients with central nervous system diseases. The findings from the two methods were compared for the capacity to defect lesions. Magnetic resonance imaging was more sensitive than or equivalent to X-ray CT in detecting lesions - especially detecting. Arnold-Chiari malformation, syringomyelia, spinal cord injury, and pituitary adenoma - in 158 patients (94 %). In six patients (10 %), lesion detection was possible only by MRI. Magnetic resonance imaging was inferior to X-ray CT in 11 patients (7 %) in detecting calcified lesions, meningioma, and cavernous hemangioma. (Namekawa, K.).

W7-AS contributions to the 18th European conference on controlled fusion and plasma heating

International Nuclear Information System (INIS)

1991-06-01

Optimum confinement in the Wendelstein 7-AS Stellarator - Ion heat conductivity, radial electric fields and CX-losses in the W7-AS stellarator - Thermal diffusivity from heat wave propagation in Wendelstein 7-AS - Impurity behaviour in W7-AS plasmas under different wall conditions - Particle transport and plasma edge behaviour in the W7-AS stellarator - Neutral injection experiments on W7-AS stellarator - MHD activity driven by NBI in the W7-AS stellarator - Simulation of the influence of coherent and random density fluctuations on the propagation of ECRH-beams in the W7-AS stellarator. (orig.)

Microemulsion synthesis and magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Beygi, H., E-mail: hossein.beygi@stu-mail.um.ac.ir; Babakhani, A.

2017-01-01

This paper investigates synthesis of Fe{sub x}Ni{sub (1−x)} bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. Fe{sub x}Ni{sub (1−x)} nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl{sub 2}·6H{sub 2}O to FeCl{sub 2}·4H{sub 2}O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties. - Highlights: • Fe{sub x}Ni{sub (1−x)} alloy NPs synthesized by simultaneous metal ions reduction in microemulsion. • Finer NPs synthesized at lower amount of oil and water and higher amount of CTAB. • Chain-like Fe{sub x}Ni{sub (1−x)} NPs are ferromagnetic; higher aspect ratio, more magnetization. • Spherical Fe{sub x}Ni({sub 1−x)} NPs with smaller size (7 nm) are superparamagnetic. • Spherical Fe{sub x}Ni{sub (1−x)} nanoparticles with higher x had increased magnetic properties.

Effect of Fe substitution on magnetocaloric effect in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (0.05{<=}x{<=}0.20)

Energy Technology Data Exchange (ETDEWEB)

Barik, S K; Krishnamoorthi, C [Department of Physics and NUS Nanoscience and Nanotechnology Initiative, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore. (Singapore); Mahendiran, R [Department of Physics and NUS Nanoscience and Nanotechnology Initiative, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore. (Singapore)

2011-04-15

We have studied the effect of Fe substitution on magnetic and magnetocaloric properties in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (x=0.05, 0.07, 0.10, 0.15, and 0.20) over a wide temperature range (T=10-400 K). It is shown that substitution by Fe gradually decreases the ferromagnetic Curie temperature (T{sub C}) and saturation magnetization up to x=0.15 but a dramatic change occurs for x=0.2. The x=0.2 sample can be considered as a phase separated compound in which both short-range ordered ferromagnetic and antiferromagnetic phases coexist. The magnetic entropy change (-{Delta}S{sub m}) was estimated from isothermal magnetization curves and it decreases with increase of Fe content from 4.4 J kg{sup -1} K{sup -1} at 343 K (x=0.05) to 1.3 J kg{sup -1} K{sup -1} at 105 K (x=0.2), under {Delta}H=5 T. The La{sub 0.7}Sr{sub 0.3}Mn{sub 0.93}Fe{sub 0.07}O{sub 3} sample shows negligible hysteresis loss, operating temperature range over 60 K around room temperature with refrigerant capacity of 225 J kg{sup -1}, and magnetic entropy of 4 J kg{sup -1} K{sup -1} which will be an interesting compound for application in room temperature refrigeration. - Research highlights: > We report magnetocaloric effect in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (x=0-0.2). > Magnetic entropy change ({Delta}S{sub m}) decreases with increasing x. > A large {Delta}S{sub m} and refrigeration capacity are found around 300 K in x=0.07.

One-dimensional model of global Alfven Eigenmodes in TORTUS and Wendelstein WVII-AS

International Nuclear Information System (INIS)

Teo, C.Y.

1998-07-01

In this article, a model for GAEs in a screw pinch plasma geometry is presented. The wave equations are derived from an ideal MHD model with corrections for finite frequency. Analytical and numerical solutions of these equations, applied to parameter sets approximating the TORTUS Tokamak and the Wendelstein WVII-AS advanced stellarator, are presented and discussed. (orig.)

Induced magnetism at the interfaces of a Fe/V superlattice investigated by resonant magnetic x-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Magnuson, Martin, E-mail: Martin.Magnuson@ifm.liu.se

2017-01-15

The induced magnetic moments in the V 3d electronic states of interface atomic layers in a Fe(6ML)/V(7ML) superlattice was investigated by x-ray resonant magnetic scattering. The first V atomic layer next to Fe was found to be strongly antiferromagnetically polarized relatively to Fe and the magnetic moments of the next few atomic layers in the interior V region decay exponentially with increasing distance from the interface, while the magnetic moments of the Fe atomic layers largely remain bulk-like. The induced V moments decay more rapidly as observed by x-ray magnetic scattering than in standard x-ray magnetic circular dichroism. The theoretical description of the induced magnetic atomic layer profile in V was found to strongly rely on the interface roughness within the superlattice period. These results provide new insight into interface magnetism by taking advantage of the enhanced depth sensitivity to the magnetic profile over a certain resonant energy bandwidth in the vicinity of the Bragg angles. - Highlights: • Magnetic moments of buried layers are probed by XRMS in a Fe/V superlattice. • The induced V magnetic moments in XRMS are more rapidly decaying than previously observed by XMCD. • The magnetic depth profile sensitivity is enhanced at an energy bandwidth in the vicinity of the Bragg angles.

Sniffer probe measurements in W7-AS

International Nuclear Information System (INIS)

Wolff, H.; Pech, P.; Grigull, P.; Poschenrieder, W.; Roth, J.

1992-01-01

Wendelstein W7-AS is a modular Advanced Stellarator with a major radius R = 2 m, effective plasma radius a ≤ 0.2 m, fivefold symmetry of the configuration and B ≤ 2.5 Tesla. The rotational transform ι can be varied between 0.25 and 0.7, the vacuum shear being low. W7-AS allows an operation free net plasma current using ECRH and/or NBI up to 3 seconds. Typical plasma parameters obtained with ECRH are T e ≤ 3 keV, T i ≤ 0.7 keV with central densities n eo 19 m -3 . The maximum electron density obtained with NBI heating was n eo = 3 x 10 20 m -3 , the energy confinement time ranges between 5 and 30 ms. (orig.)

X-ray magnetic circular dichroism used to image magnetic domains

CERN Document Server

Fischer, P; Kalchgruber, R; Schütz, G M; Schmahl, G; Guttmann, P; Bayreuther, G

1999-01-01

A new technique to image magnetic domain structures has been established by the combination of the high resolution transmission X- ray microscope (TXM) at BESSY I based on the zone plate technique with the X-ray magnetic circular $9 dichroism (X-MCD) providing a huge magnetic contrast. A lateral spatial resolution down to 30 nm could be achieved. Basic features of X-MCD are the inherent element- specificity and the potential to gain information on the local spin $9 and orbital moments of the absorbing species applying magneto-optical sum rules. Key results at the Fe L/sub 3,2/ edges of Fe in a layered GdFe system and at the Co L/sub 3/ edge of a PtCo layered system demonstrate the potential of $9 this microscopy. The images can be recorded in varying magnetic fields which allows to study the evolution of magnetic domains within a complete hysteresis loop. (8 refs).

Superconducting, magnetic and magnetotransport properties of FeTe1-xSex single crystals

Science.gov (United States)

Kumar, Rohit; Sudesh, Varma, G. D.

2018-05-01

The single crystalline samples with compositions FeTe1-xSex (0.25 ≤ x ≤ 0.50) have been prepared via self-flux method and the superconducting, magnetic and magnetotransport properties of the grown crystals were investigated. The superconducting onset temperatures have been determined from the measurements of zero field cooled magnetization and resistance with temperatures. In the present case, highest superconducting transition temperature TC (onset) ˜ 15 K has been obtained for x=0.5. The HC2 (T=0 K) values have been estimated by fitting the experimental HC2 - T plots with WHH model. The highest HC2(0) has been obtained for x=0.5. The activation energy of the thermally activated flux flow has been found from the broadening of superconducting transition in an applied magnetic field using the Arrhenius law. Our results show that the activation energy (U0) decreases with the increasing magnetic field. Furthermore, the magnetization measurements for x=0.4 and 0.5 samples have been performed at T=5 K in the magnetic field range ±7 T to estimate critical current density at different applied magnetic fields using Bean formula. We see that the sample x=0.5 has higher values of JC as compared to that of x=0.4 at all magnetic fields. This is in conformity with the behavior of U0-H plots.

Frustrated magnetization in PrxLa1-xBaCuO5Fe

International Nuclear Information System (INIS)

Ortiz, W.A.; Araujo-Moreira, F.M.; Prassides, K.

1999-01-01

The crystal structure of the system Pr x La 1-x BaCuO 5 Fe has been recently reviewed. The magnetic structure of samples with x = 0 and x = 1 is mainly due to effective local moments of iron and copper. In Pr-rich samples, Fe ions occupy two non-equivalent positions, making it substantially plausible that two or more magnetic subsets might coexist in the system. This contribution presents magnetization studies on five samples of the Pr x La 1-x BaCuO 5 Fe system (x = 0.0, 0.2, 0.5, 0.7 and 1.0). All samples exhibit a strong irreversible behavior between zero-field-cooled and field-cooled procedures below a certain irreversibility temperature T i . Above T i , both branches are coincident and well described by a Curie-Weiss fitting. Decreasing the temperature below T i , the zero-field-cooled response increases less than the field-cooled curve, indicating some degree of frustrated antiferromagnetic couplings. (orig.)

Magnetic properties and magnetocaloric effect in the HoNi1−xCuxIn (x=0, 0.1, 0.3, 0.4) intermetallic compounds

International Nuclear Information System (INIS)

Mo, Zhao-Jun; Shen, Jun; Yan, Li-Qin; Tang, Cheng-Chun; He, Xiao-Nan; Zheng, Xinqi; Wu, Jian-Feng; Sun, Ji-Rong; Shen, Bao-Gen

2014-01-01

The magnetic properties and magnetocaloric effect (MCE) in HoNi 1−x Cu x In (x=0, 0.1, 0.3, 0.4) compounds have been investigated. With the substitution of Cu for Ni, the Ho magnetic moment will cant from the c-axis, and form a complicated magnetic structure. These compounds exhibit two successive magnetic transitions with the increase in temperature. The large reversible magnetocaloric effects have been observed in HoNi 1−x Cu x In compounds around T ord , with no thermal and magnetic hysteresis loss. The large reversible isothermal magnetic entropy change (−ΔS M ) is 20.2 J/kg K and the refrigeration capacity (RC) reaches 356.7 J/kg for field changes of 5 T for HoNi 0.7 Cu 0.3 In. Especially, the value of −ΔS M (12.5 J/kg K) and the large RC (132 J/kg) are observed for field changes of 2 T for HoNi 0.9 Cu 0.1 In. Additionally, the values of RC are improved to 149 J/K for the field changes of 2 T due to a wide temperature span for the mix of HoNi 0.9 Cu 0.1 In and HoNi 0.7 Cu 0.3 In compounds with the mass ratio of 1:1. These compounds with excellent MCE are expected to have effective applications in magnetic refrigeration around 20 K. - Highlights: • For magnetic-field changes of 2 T, the values of RC are improved to 149 J/K. • MCEs of these compounds show no thermal and magnetic hysteresis. • Compounds show two successive magnetic transitions with the increase in temperature. • With the substitution of Cu for Ni, compounds form a complicated magnetic structure

Magnetic correlations in UPt3 and U/sub 1-x/Th/sub x/Pt3

International Nuclear Information System (INIS)

Aeppli, G.; Bucher, E.; Goldman, A.I.; Shirane, G.; Broholm, C.; Kjems, J.K.

1988-01-01

Neutron scattering experiments on UPt 3 and U/sub 1-x/Th/sub x/Pt 3 are reviewed. At relatively high energies (/approximately/5 MeV), the magnetic fluctuation spectrum is modulated by the structure factor derived from short-range antiferromagnetic correlations where the two U ions in each unit cell are oppositely polarized. In contrast, at low energies (≤ 1 MeV), the diffuse inelastic scattering is associated with antiferromagnetic correlations where the unit cell is doubled. Nominally pure UPt 3 exhibits magnetic order with the wavevector corresponding to this doubling and a static moment of 0.02 +- 0.01 μ/sub B/. (U/sub 1-x/Th/sub x/)Pt 3 with x ≅ 0.05 exhibits ordering of the same type, but with a much larger static moment, 0.65 +- 0.1 μ/sub B/. Neutron scattering measurements on UPt 3 with implications for superconductivity are surveyed. 23 refs., 7 figs

Magnetic relaxation phenomena in the chiral magnet Fe1 -xCoxSi : An ac susceptibility study

Science.gov (United States)

Bannenberg, L. J.; Lefering, A. J. E.; Kakurai, K.; Onose, Y.; Endoh, Y.; Tokura, Y.; Pappas, C.

2016-10-01

We present a systematic study of the ac susceptibility of the chiral magnet Fe1 -xCoxSi with x =0.30 covering four orders of magnitude in frequencies from 0.1 Hz to 1 kHz, with particular emphasis to the pronounced history dependence. Characteristic relaxation times ranging from a few milliseconds to tens of seconds are observed around the skyrmion lattice A phase, the helical-to-conical transition and in a region above TC. The distribution of relaxation frequencies around the A phase is broad, asymmetric, and originates from multiple coexisting relaxation processes. The pronounced dependence of the magnetic phase diagram on the magnetic history and cooling rates as well as the asymmetric frequency dependence and slow dynamics suggest more complicated physical phenomena in Fe0.7Co0.3Si than in other chiral magnets.

Collisionless microinstabilities in stellarators. II. Numerical simulations

International Nuclear Information System (INIS)

Proll, J. H. E.; Xanthopoulos, P.; Helander, P.

2013-01-01

Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations

Edge modelling for W7-X

International Nuclear Information System (INIS)

Schneider, R.; Borchardt, M.; Riemann, J.; Bonnin, X.; Nuehrenberg, J.; Mutzke, A.

2001-01-01

The edge modelling activities for W7-X are summarized. The status of the new 3D SOL transport code BoRiS is presented, including an algorithm for calculation of magnetic coordinates and metric coefficients. In addition, the analysis of a toroidally averaged island topology with respect to the effect of drift and currents is discussed using the 2D B2-solps5.0 code. (author)

Influence of Y{sup 3+} substitution on the structural and magnetic properties of Sr{sub 0.7}La{sub 0.3}Fe{sub 11.75-x}Y{sub x}Co{sub 0.25}O{sub 19} hexagonal ferrites

Energy Technology Data Exchange (ETDEWEB)

Zhang, Cong; Liu, Xiansong; Rehman, Khalid Mehmood Ur; Liu, Chaocheng; Li, Haohao; Meng, Xiangyu [Anhui University, School of Physics and Materials Science, Hefei (China); Anhui University, School of Physics and Materials Science, Engineering Technology Research Center of Magnetic Materials, Hefei (China)

2017-08-15

In this study, the Y{sup 3+} ion-substituted M-type Sr{sub 0.7}La{sub 0.3}Fe{sub 11.75-x}Y{sub x}Co{sub 0.25}O{sub 19} (0 ≤ x ≤ 0.2) hexagonal ferrites were synthesized by the traditional ceramic method. The structural, morphological, and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer techniques. The results show that a single M-type strontium ferrite was obtained with the Yttrium content (x) from 0 to 0.08, and the impure phase appeared when x is above 0.08. SEM images indicate the hexagonal platelet-like particles, and the size of the materials is about 3-5 μm. The saturation magnetization (M{sub s}) and coercivity (H{sub c}) of the magnetic powders both increased with the increase of x from 0 to 0.12, then decreased with the increase of x from 0.16 to 0.2. (orig.)

Structure and magnetic properties of GdxY1−xFeO3 obtained by mechanosynthesis

International Nuclear Information System (INIS)

Bolarín-Miró, A.M.; Sánchez-De Jesús, F.; Cortés-Escobedo, C.A.; Valenzuela, R.; Ammar, S.

2014-01-01

Highlights: • Orthohombic GDxY1-xFeO3 was obtained by mechanosynthesis after 5 h of milling. • Mechanosynthesized GdxY1-xFeO3 show weak ferromagnetic behavior. • Mechanosynthesis promotes unexpected magnetic properties in GdxY1-xFeO3. • The maximum magnetization that was reached 7.7 emu/g for Gdo.75Y0.25FeO3. • For Gd0.5Y0.5FeO3, the magnetization decreases down to 2.1 emu/g. -- Abstract: Solid solutions of yttrium–gadolinium orthoferrites Gd x Y 1−x FeO 3 (0 ⩽ x ⩽ 1) were prepared by high-energy ball milling. The aim of this work was to study the influence of the synthesis parameters on the crystal structure and the magnetic behavior of these solid solutions. The precursors, Fe 2 O 3 , Y 2 O 3 and Gd 2 O 3 , mixed in a stoichiometric ratio to obtain these orthoferrites, were milled for different times (up to 5 h). X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the milling time. Results showed the complete formation of orthoferrite with an orthorhombic structure (S.G. Pbnm) without any annealing after 5 h of milling for all of the compositions. The effect of the synthesis process and the x value on the crystal structure and the magnetic properties were also studied. All of the synthesized powders demonstrated weak ferromagnetic behavior. In particular, an increase in the maximum magnetization for all the compositions was found, with a maximum that reached 7.7 emu/g for Gd 0.75 Y 0.25 FeO 3 . For Gd 0.5 Y 0.5 FeO 3 , the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments

Table of charged particle energies versus magnetic field strength x orbit radius (Bρ) for A = 1 to 7 (100< (Bρ) < 1200 kG.cm)

International Nuclear Information System (INIS)

Bianchi, L.

1969-01-01

A table of charged particle energies versus magnetic field strength x orbit radius (B ρ ) is presented. Particles p, d, t, 3 He ++ , 4 He + , 4 He ++ , 6 Li + , 6 Li ++ , 6 Li +++ , 7 Li + , 7 Li ++ , 7 Li +++ . Values of B ρ : 100 to 1200 kG.cm by steps of 0.5 kG.cm. Values of energies are given in keV. (author) [fr

Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) with Th{sub 7}Fe{sub 3}-type structure

Energy Technology Data Exchange (ETDEWEB)

Misse, Patrick R.N.; Mbarki, Mohammed [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany); Fokwa, Boniface P.T., E-mail: boniface.fokwa@ac.rwth-aachen.de [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany)

2012-08-15

Powder samples and single crystals of the new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. - Graphical abstract: The new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) has been synthesized by arc melting the elements under purified argon atmosphere. Beside the 3d/4d site preference within the whole solid solution, an unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. Highlights: Black-Right-Pointing-Pointer Synthesis of a new boride series fulfilling Vegard Acute-Accent s rule. Black-Right-Pointing-Pointer 3d/4d site preference. Black-Right-Pointing-Pointer Unexpected Ru/Rh site preference. Black-Right-Pointing-Pointer Rh-rich region is Pauli paramagnetic. Black-Right-Pointing-Pointer Ru-rich region is Pauli and temperature-dependent paramagnetic.

Dynamic magnetic x-points

International Nuclear Information System (INIS)

Leboeuf, J.N.; Tajima, T.; Dawson, J.M.

1981-03-01

Two-and-one-half dimensional magnetostatic and electromagnetic particle simulations of time-varying magnetic x-points and the associated plasma response are reported. The stability and topology depend on the crossing angle of the field lines at the x-point, irrespective of the plasma β. The electrostatic field and finite Larmor radius effects play an important role in current penetration and shaping of the plasma flow. The snapping of the field lines, and dragging of the plasma into, and confinement of the plasma at, an o-point (magnetic island) is observed. Magnetic island coalescence with explosive growth of the coalescence mode occurs and is accompanied by a large increase of kinetic energy and temperature as well as the formation of hot tails on the distribution functions

Irreversibility Curve on Y1–xLuxBa2Cu3O7–δ (x=0.4, 0.5 and 0.6) superconducting

International Nuclear Information System (INIS)

Grimaldos, J F Cepeda; Supelano G, I; Santos, A Sarmiento; Chiquillo, M V; Martínez B, D; Vargas, C A Parra

2014-01-01

The irreversibility line in the H–T plane divides the irreversible and reversible behaviour of the magnetization which is of importance for the characterization of high T c superconductors. In this work, we report the production of Y 1–X Lu X Ba 2 Cu 3 O 7–δ (X=0.4, 0.5 and 0.6) superconducting system using the usual solid state reaction method. The irreversibility line H–T plane for the Y 1–X Lu X Ba 2 Cu 3 O 7–δ polycrystalline sample was investigated. The curves of magnetization ZFC (cero field cooled)- FC (field cooled) were measured in magnetic fields between 100 Oe and 4000 Oe, and allowed to obtain the values for irreversibility and critical temperatures

Low-temperature magnetic ordering in the perovskites Pr 1-xA xCoO 3 (A=Ca, Sr)

Science.gov (United States)

Deac, Iosif G.; Tetean, Romulus; Balasz, Istvan; Burzo, Emil

2010-05-01

The magnetic and electrical properties of polycrystalline Pr 1-xA xCoO 3 cobaltites with A=Ca, Sr and 0≤ x≤0.5 were studied in the temperature range 4 K≤ T≤1000 K and field up to 7 T. The X-ray analyses show the presence of only one phase having monoclinic or orthorhombic symmetry. The magnetic measurements indicate that the Ca-doped samples have at low temperatures, similar properties to the frustrated magnetic materials. PrCoO 3 is a paramagnetic insulator in the range from 4 to 1000 K. The Sr-doped cobaltites exhibit two phase transitions: a paramagnetic-ferromagnetic (or magnetic phase separated state) phase transition at about 240 K and a second one at about 100 K. The magnetic measurements suggest the presence of magnetic clusters and a change in the nature of magnetic coupling between Co ions at low temperatures. A semiconducting type behavior and high negative magnetoresistance was found for the Ca-doped samples, while the Sr-doped ones were metallic and with negligible magnetoresistance. The results are analyzed in the frame of a phase separation scenario in the presence of the spin-state transitions of Co ions.

Absence of magnetic long-range order in Y2CrSbO7 : Bond-disorder-induced magnetic frustration in a ferromagnetic pyrochlore

Science.gov (United States)

Shen, L.; Greaves, C.; Riyat, R.; Hansen, T. C.; Blackburn, E.

2017-09-01

The consequences of random nonmagnetic-ion dilution for the pyrochlore family Y2(M 1 -xN x)2O7 (M = magnetic ion, N = nonmagnetic ion) have been investigated. As a first step, we experimentally examine the magnetic properties of Y2CrSbO7 (x =0.5 ), in which the magnetic sites (Cr3 +) are percolative. Although the effective Cr-Cr spin exchange is ferromagnetic, as evidenced by a positive Curie-Weiss temperature, ΘCW ≃19.5 K , our high-resolution neutron powder diffraction measurements detect no sign of magnetic long-range order down to 2 K. In order to understand our observations, we construct a lattice model to numerically study the bond disorder introduced by the ionic size mismatch between M and N , which reveals that the bond disorder percolates at xb ≃0.23 , explaining the absence of magnetic long-range order. This model could be applied to a series of frustrated magnets with a pyrochlore sublattice, for example, the spinel compound Zn (Cr1 -xGax )2O4 , wherein a Néel to spin glass phase transition occurs between x =0.2 and 0.25 [Lee et al., Phys. Rev. B 77, 014405 (2008), 10.1103/PhysRevB.77.014405]. Our study stresses the non-negligible role of bond disorder on magnetic frustration, even in ferromagnets.

Structure and some magnetic properties of (BiFeO3x-(BaTiO31−x solid solutions prepared by solid-state sintering

Directory of Open Access Journals (Sweden)

Kowal Karol

2015-03-01

Full Text Available This paper presents the results of the study on structure and magnetic properties of the perovskite-type (BiFeO3x-(BaTiO31−x solid solutions. The samples differing in the chemical composition (x = 0.9, 0.8, and 0.7 were produced according to the conventional solid-state sintering method from the mixture of powders. Moreover, three different variants of the fabrication process differing in the temperatures and soaking time were applied. The results of X-ray diffraction (XRD, Mössbauer spectroscopy (MS, and vibrating sample magnetometry (VSM were collected and compared for the set of the investigated materials. The structural transformation from rhombohedral to cubic symmetry was observed for the samples with x = 0.7. With increasing of BaTiO3 concentration Mössbauer spectra become broadened reflecting various configurations of atoms around 57Fe probes. Moreover, gradual decreasing of the average hyperfine magnetic field and macroscopic magnetization were observed with x decreasing.

Magnetic behavior of NixFe(100-x) (65=<x=<100) nanowire arrays

International Nuclear Information System (INIS)

Navas, D.; Asenjo, A.; Jaafar, M.; Pirota, K.R.; Hernandez-Velez, M.; Sanz, R.; Lee, W.; Nielsch, K.; Batallan, F.; Vazquez, M.

2005-01-01

Arrays of magnetic nanowires with composition Ni x Fe (100-x) (65= 2 and 105nm lattice parameter of hexagonal symmetry, is achieved by self-ordering process, and characterized by SEM and AFM. Magnetic behavior of the arrays has been determined by VSM. Maximum coercivity of around 1.23kOe and reduced remanence (about 0.8 saturation magnetization) is observed for x=77, while minimum values are observed for x=100. Detailed AFM and MFM studies allow us to gain additional information of the filling degree of pores which can result in a distributed nanowires length that finally correlates with a deterioration of macroscopic magnetic behavior of the array

Magnetic properties of CE(Fe sub(1-x) Al sub(x))2 for x<=0.20

International Nuclear Information System (INIS)

Franceschini, D.F.; Cunha, S.F. da.

1985-01-01

Magnetization measurements of the system Ce(Fe sub(1-x) Al sub(x)) 2 for x 2 has not a simple dilution effect. Together with a accentuated decrease in the iron mean magnetic moment and in Curie temperatures was observed, above a certain concentration, a transition from ferromagnetism to a canted spin phase upon decreasing temperature. For the higher concentration range the system exhibits magnetic freezing effects. A preliminary magnetic phase diagram was proposed. (Author) [pt

Magneto-electric properties and magnetic entropy change in perovskite La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Ti{sub x}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Bau, Le Viet, E-mail: levietbau@hdu.edu.vn; An, Nguyen Manh

2016-12-15

The ceramic samples of La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Ti{sub x}O{sub 3}(x=0; 0.05; 0.1; 0.2 and 0.3) were synthesized by the conventional solid state reaction method. Their electric, magnetic and magnetocaloric properties have been investigated. The transition temperature declines and a significant influence on the width of the ferro-paramagnetic phase transition is observed as increasing Ti concentration. Moreover, the sign of spin-glass is expected to exist in the high concentration samples. For fully replacing Ti{sup 4+} for Mn{sup 4+}, the canted spin state is formed. The substitution Ti for Mn increases resistivity quickly and the insulating–metallic transition temperature shifts toward lower temperature. For x>0.1 samples, the insulating state is observed even in ferromagnetic phase. The substitution Ti shifts the CME to room temperature while almost persists the value of entropy change. Although the maximum value of CME reduces slightly, the temperature range happening MCE is expended and then improves the relative cooling power. These properties could be explained in term of DE interaction and phase separation phenomenon. - Highlights: • Electro-magnetic properties and CME of La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Ti{sub x}O{sub 3} have been investigated. • T{sub C} declines and the width of the F-M phase transition is observed as increasing Ti concentration. • For fully replacing Ti{sup 4+} for Mn{sup 4+}, the canted spin state is formed. • The substitution Ti for Mn increases resistivity quickly and T{sub P} shifts toward lower temperature. • The substitution Ti shifts CME to 300 K while almost persists the value of entropy change. • Relative cooling power (RCP) increases with substitution 5% Ti for Mn.

Crystal structure and magnetic properties of La2−x(Sr0.5Ca0.5)1+xMn2O7 (x=0.6, 0.8 and 1.0) Ruddlesden–Popper manganites

International Nuclear Information System (INIS)

Raju, K.; Song, M.S.; Lee, J.Y.

2014-01-01

Double layer perovskite (Ruddlesden–Popper) manganites with the nominal composition of La 2−x (Sr 0.5 Ca 0.5 ) 1+x Mn 2 O 7 (x=0.6, 0.8 and 1.0) were synthesized via a solid state reaction route. X-ray and neutron diffraction were performed at room temperature and the crystal structure was refined using the Rietveld method based on the space group, I4/mmm. The temperature variation of the susceptibility revealed a spin glass transition at 28 K for x=0.6, a charge ordering transition at 245 K and a Neel transition at 170 K for x=1.0. - Highlights: • Lanthanum based double layered manganites were prepared by doping with the same amounts of Sr and Ca. • X-ray and neutron diffraction were performed and the crystal structure was refined using the Rietveld method. • Different magnetic transitions were observed depending upon the doping concentration. • Qualitative explanation for the various observed phenomena was given

Ferrimagnetic resonance study on photo-induced magnetism in hybrid magnetic semiconductor V(TCNE)x, x ˜2 film

Science.gov (United States)

Yoo, Jung-Woo; Shima Edelstein, R.; Lincoln, D. M.; Epstein, A. J.

2007-03-01

The V(TCNE)x, x˜2 is a fully spin-polarized magnetic semiconductor, whose magnetic order exceeds room temperature (Tc > 350 K), and electronic transport follows hopping mechanism through the Coulomb energy split &*circ; subband. In addition, it was determined that this material has thermally reversible persistent change in both magnetism and conductivity driven by the optical excitation [1]. Here, we report detailed investigation on photo-induced magnetism in V(TCNE)x by employing ferrimagnetic resonance (PIFMR) study with an in-situ light illumination. Upon optical excitation (λ˜ 457.9 nm), the FMR spectra display substantial change in their linewidth and resonance field. Angular dependence analyses of line shift indicate the increase of unixial anisotropy field in the film caused by the light irradiation. The results demonstrated that the change in overall magnetic anisotropy by the illumination plays an important role in inducing photo- induced magnetism in (TCNE) class magnet. [1] J.-W. Yoo, et al. to be published in Phys. Rev. Lett.

Structure and magnetic properties of hot deformed Nd{sub 2}Fe{sub 14}B magnets doped with DyH{sub x} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wang, C.G.; Yue, M., E-mail: yueming@bjut.edu.cn; Zhang, D.T.; Liu, W.Q.; Zhang, J.X.

2016-04-15

Commercial NdFeB powders mixed with DyH{sub x} nanoparticles are hot pressed and hot deformed into anisotropic magnets by Spark Plasma Sintering (SPS). The hot deformed magnet exhibits strong c-axis crystallographic texture. The coercivity of the magnet doped with 1.0 wt% DyH{sub x} is increased by 66.7%, compared with the magnet without DyH{sub x}, while the remanence decreases only by 3%. TEM observation shows that there exists a continuous (Nd,Dy){sub 2}Fe{sub 14}B layer between Nd-rich phase and NdFeB main phase. - Highlights: • The hot deformed magnet exhibits strong c-axis crystallographic texture. • The coercivity of the magnet significantly improved, and the remanence decreases slight. • TEM observation shows that there exists a continuous (Nd,Dy){sub 2}Fe{sub 14}B layer.

The integral analysis of 40 mm diameter pipe rupture in cooling system of fusion facility W7-X with ASTEC code

Energy Technology Data Exchange (ETDEWEB)

Kačegavičius, Tomas, E-mail: Tomas.Kacegavicius@lei.lt; Povilaitis, Mantas, E-mail: Mantas.Povilaitis@lei.lt

2015-12-15

Highlights: • The analysis of loss-of-coolant accident (LOCA) in W7-X facility. • Burst disc is sufficient to prevent pressure inside the plasma vessel exceeding 110 kPa. • Developed model of the cooling system adequately represents the expected phenomena. - Abstract: Fusion is the energy production technology, which could potentially solve problems with growing energy demand of population in the future. Wendelstein 7-X (W7-X) is an experimental facility of stellarator type, which is currently being built at the Max-Planck-Institute for Plasmaphysics located in Greifswald, Germany. W7-X shall demonstrate that in future the energy could be produced in such type of fusion reactors. The safety analysis is required before the operation of the facility could be started. A rupture of 40 mm diameter pipe, which is connected to the divertor unit (module for plasma cooling) to ensure heat removal from the vacuum vessel in case of no-plasma operation mode “baking” is one of the design basis accidents to be investigated. During “baking” mode the vacuum vessel structures and working fluid – water are heated to the temperature 160 °C. This accident was selected for the detailed analysis using integral code ASTEC, which is developed by IRSN (France) and GRS mbH (Germany). This paper presents the integral analysis of W7-X response to a selected accident scenario. The model of the main cooling circuit and “baking” circuit was developed for ASTEC code. There were analysed two cases: (1) rupture of a pipe connected to the upper divertor unit and (2) rupture of a pipe connected to the lower divertor unit. The results of analysis showed that in both cases the water is almost completely released from the units into the plasma vessel. In both cases the pressure in the plasma vessel rapidly increases and in 28 s the set point for burst disc opening is reached preventing further pressurisation.

ECRH scenarios with selective heating of trapped/passing electrons in the W7-X Stellarator

Directory of Open Access Journals (Sweden)

Marushchenko N.B.

2015-01-01

Full Text Available Using specific features of the magnetic equilibrium in the W7-X stellarator, the ECRH scenarios with combined X2 and X3 modes are discussed. The RF beams for operation with X2 and X3 modes need to be launched from low- and, via the remote steering launcher, high-field-side, respectivaly, in the different crosssections of the device where the maximum and minimum of the magnetic field located. The aim is to explore the possibility of selective heating of the different classes of electrons, passing and trapped, by changing direction of the beam for X3 or switching between the beams for X2 and X3 launched from the different ports. The numerical predictions for this kind of experiments in W7-X are performed by coupled transport and ray tracing codes

Effect of non-magnetic ions substitution on the structure and magnetic properties of Y3-xSrxFe5-xZrxO12 nanoparticles

Science.gov (United States)

Mahmoudi, Soulmaz; Gholizadeh, Ahmad

2018-06-01

In this work, Y3-xSrxZrxFe5O12 (0.0 ≤ x ≤ 0.7) were synthesized by citrate precursor method at 1050 °C. The structural and magnetic properties of Y3-xSrxFe5-xZrxO12 were studied by using the X-ray diffraction technique, scanning electron microscopy, transmission electron microscopy, the Fourier transform infrared spectroscopy and vibrating sample magnetometer. XRD analysis using X'Pert package show a pure garnet phase with cubic structure (space group Ia-3d) and the impurity phase SrZrO3 is observed when the range of x value is exceeded from 0.6. Rietveld refinement using Fullprof program shows the lattice volume expansion with increasing the degree of Sr/Zr substitution. The crystallite sizes remain constant in the range of x = 0.0 - 0.5 and then increase. The different morphology observed in SEM micrographs of the samples can be related to different values of the microstrain in the samples. The hysteresis loops of the samples reveal a superparamagnetic behaviour. Also, the drop in coercivity with increasing of the substitution is mainly originated from a reduction in the magneto-elastic anisotropy energy. The values of the saturation magnetization (MS) indicate a non-monotonically variant with increasing the Sr/Zr substitution and reach a maximum 26.14 emu/g for the sample x = 0.1 and a minimum 17.64 emu/g for x = 0.0 and x = 0.2. The variation of MS, in these samples results from a superposition of three factors; reduction of Fe3+ in a-site, change in angle FeT-O-FeO, and magnetic core size.

Results of the examinations of the W7-X pre-series target elements

International Nuclear Information System (INIS)

Boscary, J.; Boeswirth, B.; Greuner, H.; Streibl, B.; Missirlian, M.; Schlosser, J.; Schedler, B.; Scheiber, K.

2006-01-01

The highly heat-loaded area of the target plates of the WENDELSTEIN 7-X (W7-X) divertor is formed by 890 water-cooled target elements (TEs). This surface is designed to sustain a maximum stationary heat flux of 10 MW/m 2 and to remove a maximum power of 100 kW per element. Flat tiles made of CFC Sepcarb(r) NB31 are bonded to a CuCrZr heat sink. This joint is manufactured in two stages. In the first step, an OFHC copper interlayer is cast onto the tile by active metal casting (AMC(r)). At this stage, the joint copper-CFC is inspected by X-ray and lock-in thermography. In the second step, the AMC(r)-NB31 tiles are joined to CuCrZr. Two technologies have been investigated: electron beam welding (EBW) and hot isostatic pressing (HIP). The joint copper-CuCrZr is examined by ultrasonic method. At the end of the fabrication, the bond between the heat sink and the CFC tiles is inspected by thermography methods. The produced CFC NB31 material for W7-X showed a large scatter in the tensile strength in the ex-pitch direction in the range of 50 - 110 MPa. Pre-series TEs have been manufactured to qualify the design, the fabrication, the relevant non-destructive examinations (NDEs) and the delivered CFC for the serial production. The whole manufacturing route is validated if the delivered elements withstand operating conditions similar to those in W7-X in the high heat flux (HHF) test facility GLADIS without degradation of performance and integrity. HHF tests did not show any effect that could be attributed to the CFC grade or to the joining method. The HHF test results exhibited a high percentage of defective tiles, indicated by hot spots at the border of the CFC surface. Visual inspections after HHF tests have mostly correlated these spots to the initiation and /or propagation of cracks at the lateral edge of the tiles in CFC at the interface CFC-copper. The pre-series activities have been extended to reduce the stresses at the critical AMC(r) interface. By means of

Magnetic properties of RNi5-xCux intermetallics

International Nuclear Information System (INIS)

Kuchin, A.G.; Ermolenko, A.S.; Kulikov, Yu.A.; Khrabrov, V.I.; Rosenfeld, E.V.; Makarova, G.M.; Lapina, T.P.; Belozerov, Ye.V.

2006-01-01

The magnetic properties have been studied for the series of RNi 5-x Cu x intermetallics with R=Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu; x= 5-x Cu x but GdNi 5-x Cu x . These results are explained in the frame of band magnetism, random local crystal field, and domain wall pinning theories

Magnetic phase diagram of ErGe 1-xSi x (0<x<1)

Science.gov (United States)

Thuéry, P.; El Maziani, F.; Clin, M.; Schobinger-Papamantellos, P.; Buschow, K. H. J.

1993-10-01

The composition-temperature magnetic phase diagram of ErGe 1- xSi x (0 0.40. For 0.17 ≥ x ≤ 0.55, a first-order transition occurs as function of the temperature between these two phases. For x ≥ 0.65, a lock-in transition takes place at TIC, leading from the wavevector ( k' x,0, k' z) to (1/2,0,1/2), as was already observed in ErSi. Finally, for x < 0.17 or 0.55 < x < 0.65, the wavevectors of the incommensurate phases characterized by (0,0, kz) or ( k' x,0, k' z) respectively remain unchanged in the whole temperature range below TN. For x≥0.65, a small amount of a magnetic phase characterized by the wavevector (0,0, 1/2) coexists with the main phases, below a Néel temperature T' N slightly lower than TN. In all cases, the erbium magnetic moments are colinear along the orthorhombic α-axis; the arrangement of the moments in the commensurate phases is the same as in ErSi and the incommensurate orderings correspond to sine-wave amplitude modulations. A brief account on the theoretical interpretation of this phase diagram is finally given.

Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

Energy Technology Data Exchange (ETDEWEB)

Higley, Daniel J., E-mail: dhigley@stanford.edu; Yuan, Edwin [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Lutman, Alberto A.; Coslovich, Giacomo; Hart, Philip; Hoffmann, Matthias C.; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Stöhr, Joachim; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Liu, Tianmin; MacArthur, James P. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); and others

2016-03-15

X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L{sub 3,2}-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

Crystal structure and magnetic properties of PrCo6.8-xCuxHf0.2 compounds

International Nuclear Information System (INIS)

Luo, J; Liang, J K; Guo, Y Q; Liu, Q L; Liu, F S; Yang, L T; Zhang, Y; Rao, G H

2004-01-01

The effects of Cu substitution on the crystal structure and magnetic properties of PrCo 6.8-x Cu x Hf 0.2 (x = 0-1.0) compounds were investigated by means of x-ray powder diffraction and magnetic measurements. The as-cast PrCo 6.8-x Cu x Hf 0.2 compounds crystallize in the TbCu 7 -type structure with the space group P6/mmm. The Curie temperature and magnetic anisotropy field decrease with increasing Cu content. A spin reorientation behaviour has been observed in the PrCo 6.8-x Cu x Hf 0.2 compounds. The addition of Cu weakens the anisotropy of the Co sublattice, leading to an increase in the spin reorientation temperature with increasing content of Cu

X-ray magnetic microscopy for correlations between magnetic domains and crystal structure

International Nuclear Information System (INIS)

Denbeaux, G.; Anderson, E.; Bates, B.; Chao, W.; Liddle, J.A.; Harteneck, B.; Pearson, A.; Salmassi, F.; Schneider, G.; Fischer, P.; Eimuller, T.; Taylor, S.; Chang, H.; Kusinski, G.J.

2002-01-01

Accurately determining the resolution of x-ray microscopes has been a challenge because good test patterns for x-ray microscopy have been hard to make. We report on a sputter-deposited multilayer imaged in cross section as a test pattern with small features and high aspect ratios. One application of high-resolution imaging is magnetic materials. Off-axis bend magnet radiation is known to have a component of circular polarization which can be used for x-ray magnetic circular dichroism. We calculate the integrated circular polarization collected by the illumination optics in the XM-1 full-field x-ray microscope. (authors)

Computational alloy design of (Co1-xNix)88Zr7B4Cu1 nanocomposite soft magnets

Science.gov (United States)

Dong, B.; Healy, J.; Lan, S.; Daniil, M.; Willard, M. A.

2018-05-01

The dependence of coercivity on composition is an important factor for establishing optimized soft magnetic properties. In this study, we have used the random anisotropy and coherent rotation models to estimate the variation of coercivity with composition in (Co1-xNix)88Zr7B4Cu1 nanocomposite alloys. Our calculations that the magnetoelastic anisotropy contribution to coercivity dominates for Ni rich compositions (x > 0.5). A small range of compositions (0.65 < x < 0.75) is predicted to result in low values of coercivity (<10 A/m). To validate this prediction, (Co1-xNix)88Zr7B4Cu1 nanocomposites in this range were prepared by melt spinning followed by 3600 s isothermal annealing at the primary crystallization peak temperature (˜673 K). Hysteresis loops were measured using vibrating sample magnetometry at room temperature and saturation magnetostriction was measured using a strain gage based magnetostrictometer. Moderately small coercivities (30-40 A/m) and magnetostrictions (3-4 ppm) were measured at for samples with 0.685 < x < 0.725. Our measured coercivity had a minimum value of 32 A/m at x = 0.725, a shift in composition of about 5 at% in the direction of higher Ni content and without the anticipated low value of coercivity. Several reasons for the inaccuracy of this approach are described, including: ignored contributions from amorphous phase (especially in magnetoealstic anisotropy), composition segregation during crystallization leading to unpredictable compositional shifts in prediction, and the general observation that the predictability of minimum coercivity from minimal combined anisotropies has unexplained deviation even in far less complicated materials.

The Co59 nuclear magnetic resonances in (Ysub(1-x)Gdsub(x))2Co17

International Nuclear Information System (INIS)

Nagai, Hiroyuki; Yoshie, Hiroshi; Unate, Takao; Tsujimura, Akira; Deportes, J.

1976-01-01

The nuclear magnetic resonances of Co 59 in (Ysub(1-x)Gdsub(x)) 2 Co 17 have been observed at 77 K as a function of x (0 2 Co 17 and Gd 2 Co 17 is at most 7 kOe in magnitude, which is comparable to that obtained in GdCo 5 . The sign of the obtained difference depends on the Co sites. The difference is qualitatively explained as the contribution of 4f electrons of Gd atoms to the hyperfine field. The temperature dependence of the resonance frequencies in Gd 2 Co 17 has also been measured. (auth.)

IPP annual report 1981

International Nuclear Information System (INIS)

1982-01-01

In part A of this annual report the tokamak and stellarator projects at the IPP are reported: ASDEX, ASDEX upgrade, JET collaboration, NET collaboration, Wendelstein VII-7, Wendelstein VII-AS, Wendelstein VII-X and stellarator reactor system studies. In part B the departments and research groups give a brief, but detailed report of the results in the field of research and development. In part C a review is presented of the IPP organisation. Part D includes the papers and conference reports published in 1981. Finally a brief description of the IPP projects at German universities is presented. (GG) [de

Ab-initio calculations of Co-based diluted magnetic semiconductors Cd 1-xCoxX (X=S, Se, Te)

KAUST Repository

Saeed, Yasir; Nazir, Safdar; Shaukat, Ali; Reshak, A. H.

2010-01-01

Ab-initio calculations are performed to investigate the structural, electronic and magnetic properties of spin-polarized diluted magnetic semiconductors composed of IIVI compounds Cd1-xCoxX (X=S, Se, Te) at x=0.25. From the calculated results

Magnetic spin configuration in Fe{sub 50}Pt{sub 50-x}Rh{sub x} alloys

Energy Technology Data Exchange (ETDEWEB)

Fenske, J.; Lott, D.; Schreyer, A. [GKSS Research Centre (Germany); Mankey, G.J. [University of Alabama, MINT Center (United States); Schmidt, W.; Schmalzl, K. [Juelich Research Centre (Germany); Tartakowskaya, E. [Institute for Magnetism, National Ukrainian Accademy of Science (Ukraine)

2010-07-01

FePt-based alloys are typically the material of choice for magnetic information storage media. The high magnetic moment of Fe gives a large magnetization and the large atomic number of Pt results in a high magnetic anisotropy. This combination enables the written bits to be smaller than ever before. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Bulk samples of Fe{sub 50}Pt{sub 50-x}Rh{sub x} studied by magnetization measurements refer to three different phase transitions with increasing temperature: (I) An antiferromagnetic (AF)-paramagnetic (PM) transition for 30<x<14.25, (II), an AF-ferromagnetic (FM) transition for 14.25<x<9.5 and, (III), a FM-PM transition 9.5<x<0. Here we present results on a series of 200 nm Fe{sub 50}Pt{sub 50-x}Rh{sub x} films with different Rh concentrations. These films were examined by neutron diffraction in dependence of temperature and magnetic field. By the use of polarized and unpolarized neutron diffraction we could develop a detailed model of the magnetic spin structure in these thin films.

Magnetic properties and coercivity mechanism of Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes prepared by surfactant-assisted ball milling

Energy Technology Data Exchange (ETDEWEB)

Xu, M. L.; Yue, M., E-mail: yueming@bjut.edu.cn; Wu, Q.; Li, Y. Q.; Lu, Q. M. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

2016-05-15

Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes with CaCu{sub 5} structure were successfully prepared by surfactant-assisted high-energy ball milling (SAHEBM). The crystal structure and magnetic properties of Sm{sub 1-x}Pr{sub x}Co{sub 5} (x=0-0.6) nanoflakes were studied by X-ray diffraction and vibrating sample magnetometer. Effects of Pr addition on the structure, magnetic properties and coercivity mechanism of Sm{sub 1-x}Pr{sub x}Co{sub 5} nanoflakes were systematically investigated. XRD results show that all the nanoflakes have a hexagonal CaCu{sub 5}-type (Sm, Pr){sub 1}Co{sub 5} main phase and the (Sm, Pr){sub 2}Co{sub 7} impurity phase, and all of the samples exhibit a strong (00l) texture after magnetic alignment. As the Pr content increases, remanence firstly increases, then slightly reduced, while anisotropy field (H{sub A}) and H{sub ci} of decrease monotonically. Maximum energy product [(BH){sub max}] of the flakes increases first, peaks at 24.4 MGOe with Pr content of x = 0.4, then drops again. Magnetization behavior analysis indicate that the coercivity mechanism is mainly controlled by inhomogeneous domain wall pinning, and the pinning strength weakens with the increased Pr content, suggesting the great influence of H{sub A} on the coercivity of flakes.

Structure and magnetic properties of (Nd1-xErx)3Fe25Cr4.0 (0 ≤ x ≤ 0.8) compounds

International Nuclear Information System (INIS)

Luo Hongzhi; Jia Lin; Li Yangxian; Meng Fanbin; Shen Jiang; Chen Nanxian; Wu Guangheng; Yang Fuming

2004-01-01

The structure and magnetic properties of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 compounds with x = 0-0.8 have been investigated using x-ray powder diffraction (XRD) and magnetic measurements. It has been found that all the compounds crystallize in a Nd 3 (Fe,Ti) 29 -type structure. Substitution of Er for Nd leads to a contraction of the unit-cell volume. The Curie temperature, T c , and the saturation magnetization, M s , of (Nd 1-x Er x ) 3 Fe 25 Cr 4.0 decrease monotonically with increasing Er content. The easy magnetization direction (EMD) of Nd 3 Fe 25 Cr 4.0 at room temperature is close to the [040] direction but may be a little out of the basal plane. With increasing Er content, the EMD changes closer to the [40-2] direction and the tilt angle increases. Both the XRD patterns and ac susceptibility indicate the appearance of a spin reorientation for x = 0-0.4 as the temperature decreases from room temperature to 77 K. The spin reorientation temperature, T sr , increases monotonically with increasing Er content from 158 K for x = 0 to 198 K for x = 0.4. A first order magnetization process (FOMP) occurs for all the compounds, and the critical field of the FOMP decreases with increasing Er content from 6.6 T for x = 0 to 2.0 T for x = 0.7

Amorphous magnetism in Mnx Sn1-x alloys

International Nuclear Information System (INIS)

Drago, V.; Saitovitch, E.M.B.; Abd-Elmeguid, M.M.

1988-01-01

Systematic low temperature in situ 119 Sn Moessbauer effect (ME) studies in vapor quenched amorphous Mn x Sn 1-x (0.09≤ x ≤0,95) alloys between 150 and 4.2 K, are presented. Its is shown that the magnetic behavior of the system is correctly displayed by the transferred magnetic hyperfine (hf) interactions, at the 119 Sn site. A complete magnetic phase diagram is proposed, and the effect of an external magnetic field (up to about 3T) on the spin correlations in the spin-glass state is also discussed. (author) [pt

Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) with Th7Fe3-type structure

Science.gov (United States)

Misse, Patrick R. N.; Mbarki, Mohammed; Fokwa, Boniface P. T.

2012-08-01

Powder samples and single crystals of the new complex boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th7Fe3 structure type (space group P63mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region.

New representatives of the Raddlesden-Popper homologous series: anion-deficient oxides Sr3Co2-xZnxO6+δ (x=0.5, 0.7)

International Nuclear Information System (INIS)

Chupakhina, T.I.; Zajtseva, N.A.; Melkozerova, M.A.; Bazuev, G.V.

2006-01-01

New complex oxides Sr 3 Co 2-x Zn x O 6+δ (x=0.5, 0.7) of the Raddlesden-Popper homologous series are synthesized; structural characteristics and magnetic properties are investigated. Lattice parameters are determined. It is established that Sr 3 Co 1.5 Zn 0.5 O 6.25 magnetic susceptibility dependence on temperature follows Curie-Weiss law only within 250-300 K temperature range. In low temperature range the compound has spin glass properties with characteristic phenomena of magnetic and temperature hysteresis [ru

Magnetic properties of magnetic Co1-xMgxFe2O4 spinel by HTSE method

International Nuclear Information System (INIS)

Hamedoun, M.; Benyoussef, A.; Bousmina, M.

2011-01-01

Magnetic properties and exchange-coupling interactions of diluted magnetic spinels A 1-x A' x B 2 X 4 , where A and B are magnetic ions, namely Co 1-x Mg x Fe 2 O 4 , were investigated using the high-temperature series expansion method (HTSE) and the distribution method of magnetic cations in the range 0≤x≤1. The magnetic phase diagram and transition temperature versus dilution x were determined using the Pade approximants method along with HTSE. The critical exponent associated with the magnetic susceptibility γ was then deduced. The obtained results are in good agreement with experimental results and critical exponent values are consistent with those suggested by the universality hypothesis.

Magnetic structures of (Co2-xNix)(OH)PO4 (x = 0.1,0.3) spin glass-like state in antiferromagnetically ordered phases

International Nuclear Information System (INIS)

Pedro, I de; Rojo, J M; Pizarro, J L; Fernandez, J RodrIguez; Marcos, J Sanchez; Fernandez-DIaz, M T; Arriortua, M I; Rojo, T

2006-01-01

Compounds of the general formula Co 2-x Ni x (OH)PO 4 (x = 0.1, 0.3) have been synthesized under mild hydrothermal conditions. Neutron powder diffraction, susceptibility and heat capacity measurements were carried out on polycrystalline samples. The cobalt-nickel compounds are ordered as three-dimensional antiferromagnets with ordering temperatures of 70 and 64 K for x = 0.1 and x = 0.3, respectively. The magnetic study shows a spin glass-like state below 11 and 5 K for Co 1.9 Ni 0.1 (OH)PO 4 and Co 1.7 Ni 0.3 (OH)PO 4 , respectively. Specific heat data present peaks at 68 and 61 K for Co 1.9 Ni 0.1 and Co 1.7 Ni 0.3 , respectively. These peaks show broad shoulders between approximately 15 and 40 K. The lack of any distinguishable anomaly below 10 K supports the spin glass nature of the low temperature transitions. Refinement of room temperature neutron diffraction data indicates that the Ni(II) ions are in octahedral co-ordination with the practical absence of these ions in the trigonal bipyramidal sites. The magnetic structures of Co 2-x Ni x (OH)PO 4 consist of ferromagnetic arrangements between the octahedral chains and trigonal bipyramidal dimers within the xz plane with the magnetic moments along the z axis. The ferromagnetic layers are disposed antiparallel to one another along the y direction establishing the three-dimensional antiferromagnetic order (T N ∼70 K for Co 1.9 Ni 0.1 and ∼64 K for Co 1.7 Ni 0.3 ). The different exchange pathways, the anisotropy of the Co(II) ions and the frustration of the magnetic moments in the trigonal bipyramidal geometry could be responsible for the freezing process

Magnetic and magneto-transport properties of double perovskite Ba{sub 2-x}Sr{sub x}FeMoO{sub 6} system

Energy Technology Data Exchange (ETDEWEB)

Pandey, Vibhav; Verma, Vivek; Aloysius, R.P. [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi-110012 (India); Bhalla, G.L. [Department of Physics and Astrophysics, Delhi University, Delhi (India); Awana, V.P.S.; Kishan, H. [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi-110012 (India); Kotnala, R.K. [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi-110012 (India)], E-mail: rkkotnala@gmail.com

2009-07-15

The structural magnetic and magneto-transport properties of double perovskite system Ba{sub 2-x}Sr{sub x}FeMoO{sub 6} (0{<=}x{<=}1.0) prepared in bulk polycrystalline form are reported in this paper. X-ray diffraction analysis showed that samples are single phase and the lattice constants decreases with increase in the Sr content. The degree of Fe-Mo ordering has been found decreasing in the series with an increase in the Sr content. Parent compound Ba{sub 2}FeMoO{sub 6} exhibits saturation magnetic moment value of 3.54 {mu}{sub B}/f.u. at 85 K in a magnetic field of 6000 Oe. Temperature dependence of resistivity shows metallic behavior for all the samples. The magneto-resistance (MR) of the compound with x=0.4 is higher than that of the other samples. At room temperature this system shows a saturation magnetization value of 1.73 {mu}{sub B}/f.u. and MR value of 7.08% (1 T). The observed variations in the structural and magnetic properties are attributed to the change of chemical pressure due to the substitution of Sr in place of Ba. The effect of antisite disorder (ASD) defects on magneto-transport properties is studied in more detail.

Magnetic properties of Ruddlesden-Popper phases Sr3 -xYx(Fe1.25Ni0.75) O7 -δ : A combined experimental and theoretical investigation

Science.gov (United States)

Keshavarz, Samara; Kontos, Sofia; Wardecki, Dariusz; Kvashnin, Yaroslav O.; Pereiro, Manuel; Panda, Swarup K.; Sanyal, Biplab; Eriksson, Olle; Grins, Jekabs; Svensson, Gunnar; Gunnarsson, Klas; Svedlindh, Peter

2018-04-01

We present a comprehensive study of the magnetic properties of Sr3 -xYx(Fe1.25Ni0.75) O7 -δ (0 ≤x ≤0.75 ). Experimentally, the magnetic properties are investigated using superconducting quantum interference device (SQUID) magnetometry and neutron powder diffraction (NPD). This is complemented by a theoretical study based on density functional theory as well as the Heisenberg exchange parameters. Experimental results show an increase in the Néel temperature (TN) with an increase of Y concentrations and O occupancy. The NPD data reveal that all samples are antiferromagnetically ordered at low temperatures, which has been confirmed by our theoretical simulations for the selected samples. Our first-principles calculations suggest that the three-dimensional magnetic order is stabilized due to finite interlayer exchange couplings. The latter give rise to finite interlayer spin-spin correlations, which disappear above TN.

INITIATION PROCESSES FOR THE 2013 MAY 13 X1.7 LIMB FLARE

Energy Technology Data Exchange (ETDEWEB)

Shen, Jinhua [Xinjiang Astronomical Observatory, CAS, 830011, Urumqi (China); Wang, Ya; Zhou, Tuanhui; Ji, Haisheng, E-mail: jihs@pmo.ac.cn [Purple Mountain Observatory, CAS, Nanjing, 210008 (China)

2017-01-20

For the X1.7 class flare on 2013 May 13 (SOL2013-05-13T01:53), its initiation process was well observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory and the Extreme UltraViolet Imager (EUVI) on board STEREO-B . The initiation process incorporates the following phenomena: an X-ray precursor that started ∼9 minutes before flare onset, two hot magnetic loops (as seen with AIA hot channels) forming a sigmoidal core magnetic structure (as seen with the EUVI), a rapidly formed magnetic flux rope (MFR) that expands outward, and a flare loop that contracts inward. The two hot magnetic loops were activated after the occurrence of the X-ray precursor. After activation, magnetic reconnection occurred between the two hot magnetic loops (inside the sigmoid structure), which produced the expanding MFR and the contracting flare loop (CFL). The MFR and CFL can only be seen with AIA hot and cool channels, respectively. For this flare, the real initiation time can be regarded as being from the starting time of the precursor, and its impulsive phase started when the MFR began its fast expansion. In addition, the CFL and the growing postflare magnetic loops are different loop systems, and the CFL was the product of magnetic reconnection between sheared magnetic fields that also produced the MFR.

INITIATION PROCESSES FOR THE 2013 MAY 13 X1.7 LIMB FLARE

International Nuclear Information System (INIS)

Shen, Jinhua; Wang, Ya; Zhou, Tuanhui; Ji, Haisheng

2017-01-01

For the X1.7 class flare on 2013 May 13 (SOL2013-05-13T01:53), its initiation process was well observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory and the Extreme UltraViolet Imager (EUVI) on board STEREO-B . The initiation process incorporates the following phenomena: an X-ray precursor that started ∼9 minutes before flare onset, two hot magnetic loops (as seen with AIA hot channels) forming a sigmoidal core magnetic structure (as seen with the EUVI), a rapidly formed magnetic flux rope (MFR) that expands outward, and a flare loop that contracts inward. The two hot magnetic loops were activated after the occurrence of the X-ray precursor. After activation, magnetic reconnection occurred between the two hot magnetic loops (inside the sigmoid structure), which produced the expanding MFR and the contracting flare loop (CFL). The MFR and CFL can only be seen with AIA hot and cool channels, respectively. For this flare, the real initiation time can be regarded as being from the starting time of the precursor, and its impulsive phase started when the MFR began its fast expansion. In addition, the CFL and the growing postflare magnetic loops are different loop systems, and the CFL was the product of magnetic reconnection between sheared magnetic fields that also produced the MFR.

Optical and magnetic resonance investigations of Zn1-x Mn x O magnetic semiconductors

International Nuclear Information System (INIS)

Zhang Huawei; Shi Erwei; Chen Zhizhan; Liu Xuechao; Xiao Bing; Song Lixin

2006-01-01

Zn 1- x Mn x O crystallites were synthesized by hydrothermal method. X-ray diffraction, UV-Vis absorption spectroscopy, and electron paramagnetic resonance (EPR) spectra confirm the substitution of Zn site by Mn 2+ ion. The nonmonotonic variation of band gap exhibits that the short-ranged interactions between the d electrons of Mn and the s and p electrons of the host bands are dominated at lower Mn concentration (x). EPR spectra show that Mn 2+ is in exchange interaction at higher x. By using a Curie-Weiss equation on the EPR data, it is found that the dominant magnetic property is antiferromagnetic for higher x, and paramagnetic for lower x

Study of magnetic behavior in hexagonal-YMn{sub 1−x}Fe{sub x}O{sub 3} (x=0 and 0.2) nanoparticles using remanent magnetization curves

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Samta; Singh, Amit Kumar; Srivastava, Saurabh Kumar; Chandra, Ramesh, E-mail: ramesfic@iitr.ac.in

2016-09-15

We have studied the magnetic behavior of YMn{sub 1−x}Fe{sub x}O{sub 3} (x=0 and 0.2) nanoparticles synthesized by conventional solid state reaction method. The as-synthesized nanoparticles were found to have hexagonal phase with P6{sub 3cm} space group confirmed by X-Ray diffraction. The particle size was found to be ~70 nm as confirmed by both X-Ray diffraction and Transmission Electron Microscopy. DC magnetization and memory effect measurements imply that the h-YMnO{sub 3} nanoparticles bear a resemblance to super spin-glass state following de Almeida–Thouless like behavior which is being suppressed by Fe-doping. The Fe-doping in YMnO{sub 3} enhances the antiferromagnetic (AFM) transition temperature T{sub N} to ~79 K and induces a new magnetic state due to the surface spins which is realized as diluted antiferromagnet in a field (DAFF) as explored by the thermoremanent and isothermoremanent magnetization measured with different applied magnetic field. - Highlights: • Magnetic behavior of h-YMn{sub 1−x}Fe{sub x}O{sub 3} (x=0 and 0.2) nanoparticles have been studied. • The nanoparticles (~70 nm) were synthesized by solid state reaction method. • Magnetic data reveal spin-glass behavior in YMnO{sub 3} which was suppressed in YMn{sub 0.8}Fe{sub 0.2}O{sub 3}. • The h-YMnO{sub 3} nanoparticles show memory effect and obey de-Almeida Thouless line. • TRM and IRM suggest spin glass nature for YMnO{sub 3}, while the YMn{sub 0.8}Fe{sub 0.2}O{sub 3} resembles DAFF.

Giant magnetic anisotropy and tunnelling of the magnetization in Li2(Li_{1-x}Fe_x)N

OpenAIRE

Jesche, A.; McCallum, R. W.; Thimmaiah, S.; Jacobs, J. L.; Taufour, V.; Kreyssig, A.; Houk, R. S.; Bud'ko, S. L.; Canfield, P. C.

2014-01-01

Large magnetic anisotropy and coercivity are key properties of functional magnetic materials and are generally associated with rare earth elements. Here we show an extreme, uniaxial magnetic anisotropy and the emergence of magnetic hysteresis in Li2(Li1-xFex)N. An extrapolated, magnetic anisotropy field of 220 Tesla and a coercivity field of over 11 Tesla at 2 Kelvin outperform all known hard-ferromagnets and single-molecule magnets (SMMs). Steps in the hysteresis loops and relaxation phenome...

Electrical, magnetic and physical properties of YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconductor/polymer composites

International Nuclear Information System (INIS)

Fuierer, P.A.; Srinivasan, T.T.; Newnham, R.E.

1988-01-01

A polymer matrix provides a composite with flexibility and improved impact strength as well as protection against humidity and chemical attack. Superconductor/polymer 0-3 composites have been prepared by mixing YBa/sub 2/Cu/sub 3/O/sub 7-x/ powder with silicone rubber, pressing and curing. The resistivities of these composites do not go to zero, however, the magnetic flux exclusion is maintained in the temperature range, T< T/sub c/(--91K). The composite resistivities show percolation behavior and diamagnetism increases with increasing volume fraction of the superconductor filler. The composites exhibit levitation and large diamagnetic susceptibilities

Assessment of off-stoichiometric Zr33-xFe52+xSi15 C14 Laves phase compounds as permanent magnet materials

Science.gov (United States)

Gabay, A. M.; Hadjipanayis, G. C.

2018-05-01

Recently, Fe-based rare-earth-free compounds with non-cubic crystal structures were proposed as a base for permanent magnets which would not rely on critical elements. In this work, two series of alloys, Zr27Fe73-wSiw (0 ≤ w ≤ 15) and Zr33-xFe52+xSi15 (0 ≤ x ≤ 11), were prepared and characterized after annealing at 1538 K in order to determine the fundamental magnetic properties of the C36 and C14 hexagonal Laves phase compounds. A mixture of the cubic C15 and Zr6Fe23 structures was observed instead of the expected C36 structure. The hexagonal C14 was found in all Zr33-xFe52+xSi15 alloys with its lattice parameters linearly decreasing as the Fe(Si) atoms occupy the Zr sites in the Laves phase crystal structure. The solubility limit of Fe in the C14 structure at 1538 K corresponds to x = 9.5. The Curie temperature of the C14 compounds increases with deviation from the Laves phase stoichiometry from 290 K to 530 K. The room-temperature spontaneous magnetization also increases reaching, after correcting for the non-magnetic impurities, a value of 6.7 kG. The magnetocrystalline anisotropy of the off-stoichiometric C14 Laves phase was found to be uniaxial with the easy magnetization direction parallel to the hexagonal axis. Unfortunately, the anisotropy field, which does not exceed 10 kOe, is not sufficiently high to make the compounds interesting as permanent magnet materials.

Electrical characterization of chemically modified YBa2Cu3O7-x surfaces

International Nuclear Information System (INIS)

Hunt, B.D.; Foote, M.C.; Vasquez, R.P.

1990-01-01

Results on electrical characterization of YBa 2 Cu 3 O 7-x thin-film surfaces treated with a Br/ethanol chemical etch are presented. Electrical measurements of YBa 2 Cu 3 O 7-x /Au/Nb device structures fabricated using polycrystalline, post-annealed YBa 2 Cu 3 O 7-x films with Br-etched surfaces, show improvements of approximately one or two orders of magnitude in current densities and resistivities (resistance-area products) relative to unetched devices. The existence of supercurrents in these structures has been confirmed by observation of the ac Josephson effect, and by magnetic field and temperature studies of the critical currents. The Br-etch process has produced 10x10 μm 2 devices with critical current densities greater than 400 A/cm 2 and resistivities as low as 4x10 -7 Ω cm 2

Design and analysis of the W7-X divertor scraper element

International Nuclear Information System (INIS)

Lumsdaine, A.; Tipton, J.; Lore, J.; McGinnis, D.; Canik, J.; Harris, J.; Peacock, A.; Boscary, J.; Tretter, J.; Andreeva, T.

2013-01-01

Highlights: • A high heat flux actively cooled divertor component is thermally modeled with CFD. • CFC monoblocks are analyzed to verify peak steady-state temperatures do not exceed 1200 °C. • A field line diffusion code is developed to determine the heat flux on the divertor components. • Iteration is required to develop a surface that meets the criteria and fits into the limited space. -- Abstract: Thehigh heat-flux divertor of the Wendelstein 7-X large stellarator experiment consists of 10 divertor units which are designed to carry a steady-state heat flux of 10 MW/m 2 . However, the edge elements of this divertor are limited to only 5 MW/m 2 , and may be overloaded in certain plasma scenarios. It is proposed to reduce this heat by placing an additional “scraper element” in each of the ten divertor locations. It will be constructed using carbon fiber composite (CFC) monoblock technology. The design of the monoblocks and the path of the cooling tubes must be optimized in order to survive the significant steady-state heat loads, provide adequate coverage for the existing divertor, be located within sub-millimeter accuracy, and take into account the boundaries to other in vessel components, all at a minimum cost. Computational fluid dynamics modeling has been performed to examine the thermal transfer through the monoblock swirl tube channels for the design of the monoblock orientation. An iterative physics modeling and computer aided design process is being performed to optimize the placement of the scraper element within the severe spatial restrictions

Synthesis of Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} via combustion route: Effects of Al{sub 2}O{sub 3} nanoparticles on superconducting properties

Energy Technology Data Exchange (ETDEWEB)

Mohd Suan, Mohd Shahadan, E-mail: mohdshahadan@utem.edu.my [Department of Engineering Materials, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, 76100 Durian Tunggal, Melaka (Malaysia); Johan, Mohd Rafie [Nanomaterial Engineering Research Group, Advanced Materials Research Laboratory, Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2017-02-01

Combustion reaction was used to synthesis Al{sub 2}O{sub 3} nanoparticles embedded Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} simultaneously. The effects of Al{sub 2}O{sub 3} nanoparticles with nominal molar mass (x{sub mol}) of 0.02, 0.04, 0.06, 0.08 and 0.10 towards the critical current density J{sub C} of Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} were verified by magnetic measurement. Resulted XRD patterns revealed that the calcined samples consist of pure Al{sub 2}O{sub 3} and Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} phases which had been confirmed by EDX results. The SEM images showed that Al{sub 2}O{sub 3} nanoparticles (~10 nm) were distributed in polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} grains and grain boundaries. The presence of higher concentration of Al{sub 2}O{sub 3} nanoparticles has developed Al{sup 3+} rich spots which diffused within the YBa{sub 2}Cu{sub 3}O{sub 7-δ} superconducting matrix to form Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} and was confirmed by EDX analysis. The samples were electrically superconducting at temperature above 85 K as measured by using standard four-probe technique. The magnetic field (H) dependent magnetization (M), M-H hysteresis loops measured at 77 K for x{sub mol}≤0.06 samples are significantly improved attributed to the increase of trapped fluxes in the samples. Remarkable increase of magnetic J{sub C} (H) in Al{sub 2}O{sub 3} nanoparticles added samples compared to the as prepared polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} sample indicating strong pinning effect. It is suggested that well-distributed Al{sub 2}O{sub 3} nanoparticles in the polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} matrix achieved via auto-combustion reaction has efficiently pin the magnetic vortex. The magnetic J{sub C} was optimized to ~6 kAcm{sup -2} in x{sub mol}=0.06 sample. On the other hand, insignificant magnetic J{sub C} improvement in x{sub mol}≥0.08 samples is probably resulted from the

Critical current density in (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x melt-textured composites

Science.gov (United States)

Opata, Yuri Aparecido; Monteiro, João Frederico Haas Leandro; Jurelo, Alcione Roberto; Siqueira, Ezequiel Costa

2018-06-01

Melt textured (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x composites (x = 0.00 and x = 0.05) were grown using the top seeding method. The effect of the PrBa2Cu3O7-δ phase on the growth process and the modification of the microstructure as well as on the physical properties was analyzed. X-ray analyses indicated that both pure and Pr-doped samples present an orthorhombic superconducting phase. From resistivity measurements for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, the Tcab did not change and was around 90.5 K. However, from magnetic measurements, the superconductivity was observed in critical temperatures TC = 92.9 K and 92.4 K for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, respectively. The YBa2Cu3O7-δ sample showed higher critical current densities than those shown by the (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 sample, with values of JC = 5.85 × 105 A/cm2 and 4.72 × 105 A/cm2, respectively. This paper also discusses the importance of Pr substitution on nano- and micro-meter scales to enhance JC(H).

Structural, magnetic and magnetocaloric properties of La{sub 0.7}Ca{sub 0.2}Sr{sub 0.1}Mn{sub 1−x}Cr{sub x}O{sub 3} compounds with x = 0, 0.05 and 0.1

Energy Technology Data Exchange (ETDEWEB)

Dhahri, Ah., E-mail: dhahri.ahmad@outlook.fr [Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, BP 1171, Université de Sfax, 3000 (Tunisia); Jemmali, M. [Laboratoire des Sciences des Matériaux et de l’Environnement, Faculté des Sciences de Sfax, BP 1171, Université de Sfax, 3000 (Tunisia); Taibi, K. [Département SDM, FGMGP/USTHB, 16311 (Algeria); Dhahri, E. [Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, BP 1171, Université de Sfax, 3000 (Tunisia); Hlil, E.K. [Institut Néel, CNRS et Université J. Fourier, BP 166, 38042 Grenoble (France)

2015-01-05

Highlights: • The samples crystallize in the rhombohedral structure with the R3{sup ¯}c space group. • Enhancement of T{sub C} for the rhombohedral samples. • The relative cooling power increases with Cr-doping. • All samples exhibit a large magnetocaloric effect. • High values of the magnetoresistance in all samples. - Abstract: Structural, magnetic and magnetocaloric properties of La{sub 0.7}Sr{sub 0.1}Ca{sub 0.2}Mn{sub 1−x}Cr{sub x}O{sub 3} compounds with x = 0, 0.05 and 0.1 have been investigated to shed light on Cr-doping influence. X-ray diffraction studies show that all samples crystallize in the rhombohedral symmetry with R3{sup ¯}c space group. Rietveld refinement structure shows that the insertion of Cr in Mn network modifies the structural parameters such as the volume, Mn–O–Mn angles and the Mn–O bond length. The substitution of Mn by Cr decreases the 2p-3d hybridization between O and Mn ions, reduces the bandwidth and increases the electron–phonon coupling. The investigation of magnetic and magnetocaloric properties reveals that the samples exhibit a paramagnetic(PM)–ferromagnetic (FM) transition with decreasing Curie temperature (T{sub C}) from 294 K to 255 K when Cr doping level increases. The magnetic entropy change (ΔS{sub M}{sup max}) also decreases from 6.20 J kg{sup −1} K{sup −1} for x = 0 to3.80 J kg{sup −1} K{sup −1} for x = 0.1, while the relative cooling power (RCP) increases from 234.5 to 240 J kg{sup −1}, respectively, under a magnetic field of 5 T. These outcomes suggest that Mn-site Cr doping inhibits the enhancement of the magnetocaloric effect in some perovskite manganites. This is explained by the weakening of the ferromagnetic double-exchange interaction between Mn{sup 3+} and Mn{sup 4+} ions.

Structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7

Science.gov (United States)

Kumar, Harish; Chaurasia, Rachna; Kumari, Pratibha; Paramanik, A. K.

2018-04-01

We have studied the structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7. Structural investigation has been done using x-ray powder diffraction and Rietveld analysis. Pr2Ir2O7 crystallize in cubic crystallographic phase with Fd-3m space group. Temperature dependent magnetization data does not show magnetic bifurcation down to 2 K. Electrical resistivity data of Pr2Ir2O7 exhibits metallic behavior throughout temperature range. Below 50 K, a small rise in resistivity data of Pr2Ir2O7 is observed down to 12 K.

Magnetic exchange coupling in amorphous Fe80-xDy xB20 alloys

International Nuclear Information System (INIS)

Annouar, F.; Lassri, H.; Ayadi, M.; Omri, M.; Lassri, M.; Krishnan, R.

2005-01-01

Amorphous Fe 80-x Dy x B 20 alloys have been prepared by melt spinning and their magnetic properties have been studied. The mean field theory has been used to explain the temperature dependence of the magnetization. The exchange interactions between Co-Co and Dy-Co atom pairs have been evaluated. High-field magnetization studies on samples with stoichiometry close to that of a compensated ferrimagnet show a magnetic behavior that is characteristic of a non-collinear magnetic structure of the Dy and Fe sublattices. The region of the canted moments can be described by a phase diagram in the H-T plane

Nanostructure and magnetization reversal process in TbFeCo/Yx(FeCo)1-x spring-magnet type multilayers

International Nuclear Information System (INIS)

Duc, N.H.; Huong Giang, D.T.; Chau, N.

2004-01-01

Studies of the naturally formed nanostructure and magnetization reversal process were performed for the sputtered Tb(Fe 0.55 Co 0.45 ) 1.5 /Y x (Fe 0.7 Co 0.3 ) 1-x multilayers (0≤x≤0.2) with a TbFeCo layer thickness t TbFeCo =12 nm and YFeCo layer thickness t YFeCo =10 nm. The structural investigations showed that nanocrystals are naturally formed and coexist within the amorphous matrix in Y 0.1 (FeCo) 0.9 layers. In this state, low magnetic coercivity and large parallel magnetostrictive susceptibility are observed. The results are discussed in terms of the crystalline discontinuity of the soft YFeCo layers

Electrical and magnetic properties of MgGa_(_2_-_x_)Fe_xO_4 ferrite

International Nuclear Information System (INIS)

Ribeiro, Vander Alkmin dos Santos

2005-01-01

The ceramics of the type ferrites are materials that present important characteristics of electrical conduction and magnetic properties, as much as material magnetic hard, how much of soft magnetic materials. The cubic ferrites of the spinel structure are oxides with chemical formula MFe_2O_4, where M is a divalent metallic ion. Due to characteristic of the spinel, diverse magnetic configurations are a gotten, depending on the occupation tax of the magnetic ion (in general iron) in each sublattice. The diluted ferrites possess general formula given for: MD_2_-_xFe_xO4, where M and D are diamagnetic ions, being D the ion of substitution doping and x is the concentration of ions of iron (0,002 ≤ x ≤ 0,350). The sample was prepared using ceramics techniques in reaction of solid state and later they were submitted to a magnetic characterization, electric and X-ray diffraction. The results of the magnetic characterization were gotten by a magnetometer of vibrant sample (VSM) EG&G-Princeton Applied Research, model 4500; the characterization for X-ray was used one X-ray diffractometer, model URD 65; of the Seifert & with. Electrical measurements DC were carried through with the use of a unit high-voltage measuring source - Keithley, model 237, where the voltage applied in the samples varied of 0-40 V, the high temperatures. Two types of contacts were used: the arrangement type 'sandwich', being the inferior electrode the proper door-sample, and the superior electrode with ring geometry and a silver was pasted on both sides of the samples to ensure good electrical contact. The magnetic measurements confirm its ferrite characteristics and in the electrical measurements, the electrical conductivity indicated behavior of a semiconductor the high temperatures and the process of electrical conduction thermally presented to be activated. (author)

Magnetic imaging with full-field soft X-ray microscopies

International Nuclear Information System (INIS)

Fischer, Peter; Im, Mi-Young; Baldasseroni, Chloe; Bordel, Catherine; Hellman, Frances; Lee, Jong-Soo; Fadley, Charles S.

2013-01-01

Progress toward a fundamental understanding of magnetism continues to be of great scientific interest and high technological relevance. To control magnetization on the nanoscale, external magnetic fields and spin polarized currents are commonly used. In addition, novel concepts based on spin manipulation by electric fields or photons are emerging which benefit from advances in tailoring complex magnetic materials. Although the nanoscale is at the very origin of magnetic behavior, there is a new trend toward investigating mesoscale magnetic phenomena, thus adding complexity and functionality, both of which will become crucial for future magnetic devices. Advanced analytical tools are thus needed for the characterization of magnetic properties spanning the nano- to the meso-scale. Imaging magnetic structures with high spatial and temporal resolution over a large field of view and in three dimensions is therefore a key challenge. A variety of spectromicroscopic techniques address this challenge by taking advantage of variable-polarization soft X-rays, thus enabling X-ray dichroism effects provide magnetic contrast. These techniques are also capable of quantifying in an element-, valence- and site-sensitive way the basic properties of ferro(i)- and antiferro-magnetic systems, such as spin and orbital moments, spin configurations from the nano- to the meso-scale and spin dynamics with sub-ns time resolution. This paper reviews current achievements and outlines future trends with one of these spectromicroscopies, magnetic full field transmission soft X-ray microscopy (MTXM) using a few selected examples of recent research on nano- and meso-scale magnetic phenomena. The complementarity of MTXM to X-ray photoemission electron microscopy (X-PEEM) is also emphasized

Magnetic imaging with full-field soft X-ray microscopies

Energy Technology Data Exchange (ETDEWEB)

Fischer, Peter, E-mail: PJFischer@lbl.gov [Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Im, Mi-Young [Center for X-ray Optics, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Baldasseroni, Chloe [Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA 94720 (United States); Bordel, Catherine; Hellman, Frances [Department of Physics, University of California Berkeley, Berkeley, CA 94720 (United States); Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94270 (United States); Lee, Jong-Soo [Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of); Fadley, Charles S. [Department of Physics, University of California Davis, Davis, CA 95616 (United States); Material Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94270 (United States)

2013-08-15

Progress toward a fundamental understanding of magnetism continues to be of great scientific interest and high technological relevance. To control magnetization on the nanoscale, external magnetic fields and spin polarized currents are commonly used. In addition, novel concepts based on spin manipulation by electric fields or photons are emerging which benefit from advances in tailoring complex magnetic materials. Although the nanoscale is at the very origin of magnetic behavior, there is a new trend toward investigating mesoscale magnetic phenomena, thus adding complexity and functionality, both of which will become crucial for future magnetic devices. Advanced analytical tools are thus needed for the characterization of magnetic properties spanning the nano- to the meso-scale. Imaging magnetic structures with high spatial and temporal resolution over a large field of view and in three dimensions is therefore a key challenge. A variety of spectromicroscopic techniques address this challenge by taking advantage of variable-polarization soft X-rays, thus enabling X-ray dichroism effects provide magnetic contrast. These techniques are also capable of quantifying in an element-, valence- and site-sensitive way the basic properties of ferro(i)- and antiferro-magnetic systems, such as spin and orbital moments, spin configurations from the nano- to the meso-scale and spin dynamics with sub-ns time resolution. This paper reviews current achievements and outlines future trends with one of these spectromicroscopies, magnetic full field transmission soft X-ray microscopy (MTXM) using a few selected examples of recent research on nano- and meso-scale magnetic phenomena. The complementarity of MTXM to X-ray photoemission electron microscopy (X-PEEM) is also emphasized.

Importance of halogen···halogen contacts for the structural and magnetic properties of CuX2(pyrazine-N,N′-dioxide)(H2O)2 (X = Cl and Br).

Science.gov (United States)

Schlueter, John A; Park, Hyunsoo; Halder, Gregory J; Armand, William R; Dunmars, Cortney; Chapman, Karena W; Manson, Jamie L; Singleton, John; McDonald, Ross; Plonczak, Alex; Kang, Jinhee; Lee, Chaghoon; Whangbo, Myung-Hwan; Lancaster, Tom; Steele, Andrew J; Franke, Isabel; Wright, Jack D; Blundell, Stephen J; Pratt, Francis L; deGeorge, Joseph; Turnbull, Mark M; Landee, Christopher P

2012-02-20

The structural and magnetic properties of the newly crystallized CuX(2)(pyzO)(H(2)O)(2) (X = Cl, Br; pyzO = pyrazine-N,N'-dioxide) coordination polymers are reported. These isostructural compounds crystallize in the monoclinic space group C2/c with, at 150 K, a = 17.0515(7) Å, b = 5.5560(2) Å, c = 10.4254(5) Å, β = 115.400(2)°, and V = 892.21(7) Å(3) for X = Cl and a = 17.3457(8) Å, b = 5.6766(3) Å, c = 10.6979(5) Å, β = 115.593(2)°, and V = 950.01(8) Å(3) for X = Br. Their crystal structure is characterized by one-dimensional chains of Cu(2+) ions linked through bidentate pyzO ligands. These chains are joined together through OH···O hydrogen bonds between the water ligands and pyzO oxygen atoms and Cu-X···X-Cu contacts. Bulk magnetic susceptibility measurements at ambient pressure show a broad maximum at 7 (Cl) and 28 K (Br) that is indicative of short-range magnetic correlations. The dominant spin exchange is the Cu-X···X-Cu supersuperexchange because the magnetic orbital of the Cu(2+) ion is contained in the CuX(2)(H(2)O)(2) plane and the X···X contact distances are short. The magnetic data were fitted to a Heisenberg 1D uniform antiferromagnetic chain model with J(1D)/k(B) = -11.1(1) (Cl) and -45.9(1) K (Br). Magnetization saturates at fields of 16.1(3) (Cl) and 66.7(5) T (Br), from which J(1D) is determined to be -11.5(2) (Cl) and -46.4(5) K (Br). For the Br analog the pressure dependence of the magnetic susceptibility indicates a gradual increase in the magnitude of J(1D)/k(B) up to -51.2 K at 0.84 GPa, suggesting a shortening of the Br···Br contact distance under pressure. At higher pressure X-ray powder diffraction data indicates a structural phase transition at ∼3.5 GPa. Muon-spin relaxation measurements indicate that CuCl(2)(pyzO)(H(2)O)(2) is magnetically ordered with T(N) = 1.06(1) K, while the signature for long-range magnetic order in CuBr(2)(pyzO)(H(2)O)(2) was much less definitive down to 0.26 K. The results for the CuX

The effect of Ni-doping on the magnetic order in the cubic GdIn(Cu{sub 1-x}Ni{sub x})4 (0.00 < x < 1.00) compounds

Energy Technology Data Exchange (ETDEWEB)

Mendonca, Edielma Costa; Silva, Leonardo Souza; Mercena, Samuel Gomes; Peixoto, Erilaine Barreto; Meneses, Cristiano Teles de, E-mail: edielmacm@gmail.com [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil); Duque, Jose Gerivaldo; Jesus, Camilo Bruno Ramos; Pagliuso, Pascoal G. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Fisica Gleb Wataghin

2016-07-01

Full text: In this work, we report on X-ray, magnetization, heat capacity and electron spin resonance measurements in GdIn(Ni{sub x}Cu{sub 1-x}){sub 4} (0.00 < x < 1.00) samples synthesized via flux method. The analysis of X-ray powder diffraction data carried out at room temperature reveal that all samples belong to cubic space group (Cl5b-type structure) with lattice parameters ranging 7.087 < a < 7.233 Å. Interestingly, the T-dependence of magnetic susceptibility and the MvsH loops indicate an gradual transition from antiferromagnetic to ferromagnetic as function the Ni-doping. Specific heat for samples with concentrations x = 0 (Cu-rich) and x = 0.70 and 0.90 (Ni-rich) confirm the order temperatures observed in MvsT data. Finally, electron spin resonance taken in 10 < T < 60 K for two intermediate concentrations x = 0.5 and 0.65 shows a single resonance of Dysonian with a nearly temperature g-independent and a linear thermal broadening of the linewidth following a Korringa-like behavior. In both cases, we observe an increasing of the residual linewidth as compared with GdInCu{sub 4}. We suggest that this can be linked with the chemical disorder produced by the Ni-doping. (author)

Giant magnetic anisotropy and tunnelling of the magnetization in Li2(Li1-xFex)N

Energy Technology Data Exchange (ETDEWEB)

Jesche, A.; McCallum, R. W.; Thimmaiah, S.; Jacobs, J. L.; Taufour, V.; Kreyssig, A.; Houk, R. S.; Bud’ko, S. L.; Canfield, P. C.

2014-02-25

Large magnetic anisotropy and coercivity are key properties of functional magnetic materials and are generally associated with rare earth elements. Here we show an extreme, uniaxial magnetic anisotropy and the emergence of magnetic hysteresis in Li2(Li_1-xFe_x)N. An extrapolated, magnetic anisotropy field of 220 T and a coercivity field of over 11 T at 2 K outperform all known hard ferromagnets and single-molecular magnets. Steps in the hysteresis loops and relaxation phenomena in striking similarity to single-molecular magnets are particularly pronounced for x<<1 and indicate the presence of nanoscale magnetic centres. Quantum tunnelling, in the form of temperature-independent relaxation and coercivity, deviation from Arrhenius behaviour and blocking of the relaxation, dominates the magnetic properties up to 10 K. The simple crystal structure, the availability of large single crystals and the ability to vary the Fe concentration make Li2(Li_1-xFe_x)N an ideal model system to study macroscopic quantum effects at elevated temperatures and also a basis for novel functional magnetic materials.

Study of magnetic behavior in hexagonal-YMn1−xFexO3 (x=0 and 0.2) nanoparticles using remanent magnetization curves

International Nuclear Information System (INIS)

Chauhan, Samta; Singh, Amit Kumar; Srivastava, Saurabh Kumar; Chandra, Ramesh

2016-01-01

We have studied the magnetic behavior of YMn 1−x Fe x O 3 (x=0 and 0.2) nanoparticles synthesized by conventional solid state reaction method. The as-synthesized nanoparticles were found to have hexagonal phase with P6 3cm space group confirmed by X-Ray diffraction. The particle size was found to be ~70 nm as confirmed by both X-Ray diffraction and Transmission Electron Microscopy. DC magnetization and memory effect measurements imply that the h-YMnO 3 nanoparticles bear a resemblance to super spin-glass state following de Almeida–Thouless like behavior which is being suppressed by Fe-doping. The Fe-doping in YMnO 3 enhances the antiferromagnetic (AFM) transition temperature T N to ~79 K and induces a new magnetic state due to the surface spins which is realized as diluted antiferromagnet in a field (DAFF) as explored by the thermoremanent and isothermoremanent magnetization measured with different applied magnetic field. - Highlights: • Magnetic behavior of h-YMn 1−x Fe x O 3 (x=0 and 0.2) nanoparticles have been studied. • The nanoparticles (~70 nm) were synthesized by solid state reaction method. • Magnetic data reveal spin-glass behavior in YMnO 3 which was suppressed in YMn 0.8 Fe 0.2 O 3 . • The h-YMnO 3 nanoparticles show memory effect and obey de-Almeida Thouless line. • TRM and IRM suggest spin glass nature for YMnO 3 , while the YMn 0.8 Fe 0.2 O 3 resembles DAFF.