Forschungszentrum Julich Research Articles

The nuclear reaction polarimeter for a polarized-fusion project

The fusion reactions and with both deuteron beams polarized will be studied experimentally by a collaboration between the Institut für Kernphysik of Forschungszentrum Jülich (FZJ), Germany, the Laboratory of Cryogenic Techniques, St. Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia, and the St. Petersburg State University of Information Technologies, Mechanics and Optics (ITMO) in order to analyze the influence of the vector and tensor polarization on the total fusion cross section and the branching to the two reaction channels. The results shall allow to solve the discrepancy between different theoretical predictions. Moreover, the investigation of the reaction rate is of high interest, since it may lead to an increase of the efficiency of the energy generation in fusion power plants. A change of the branching ratio of the two fusion channels, i.e., suppression of neutron production as predicted by a number of theoretical papers, would decrease the radiation damage by neutrons and would allow prolongation of the operation time of a future fusion-reactor generation. The measurements request the knowledge of the polarization of both the deuteron beam and the jet target. With an unpolarized solid-state target, the beam polarization can be determined by studying the angular distributions of the outgoing ions (3He,p,t) with use of the known analyzing powers. Vice versa, additional data for the analyzing powers can be obtained, when the beam polarization is known. This is achieved by an additional (Lamb-shift) polarimeter. The setup of the polarimeter and results of detector tests are described.

Development of Metal-Supported Solid Oxide Fuel Cells

A novel generation of a thin-film, metal supported solid oxide fuel cell (MSC) has been developed and demonstrated in the scope of the NextGen MSC project (funded by the German Federal Ministry of Economics and Technology) by Plansee, Forschungszentrum Jülich (FZ-J), and the Karlsruhe Institute of Technology (KIT), respectively. In the scope of this work, due to consequent electrolyte and electrode development, a novel cell configuration, based on Plansee's well-known porous FeCr alloy as mechanical cell support, could be established. Thus, first cell measurements at KIT indicate the feasibility and the reliability of the established cell manufacturing process. The tested cell has shown a current density of 1.52 A/cm² at 0.7 V and 820 °C. This corresponds with an area specific cell performance of 1,064 mW/cm2. Furthermore, during a cell operation time of approx. 300 hrs., the cell degradation was relatively low.

Энергетические технологии — 2050

Аренс Марлен- научный сотрудник, Фраунгоферовский институт системных и инновационных исследований (Германия). E-mail: marlene.arens@isi.fraunhofer.de Адрес: Fraunhofer-Institut für System- und Innovationsforschung ISI, Breslauer Straße 48, 76139 Karlsruhe GermanyДётч Кристиан- руководитель бизнес-подразделения «Энергетические системы», Фраунгоферовский институт технологий защиты окружающей среды, обеспечения безопасности и энергетики (Германия). E-mail: christian.doetsch@umsicht.fraunhofer.de Адрес: Fraunhofer-Institut für Umwelt-, Sicherheits- und Energietechnik UMSICHT, Osterfelder Straße 3, 46047 Oberhausen GermanyКревитт Вольфрам- руководитель подразделения, Германский центр авиации и космонавтики. Адрес: Linder Hoehe 51147 Cologne GermanyМаркевиц Петер- научный сотрудник, Исследовательский центр Юлиха. E-mail: p.markewitz@fz-juelich.de Адрес: Forschungszentrum Jülich, Wilhelm-Johnen-Strasse, 52425 Jülich, GermanyМёст Доминик- руководитель проектов, Высшая техническая школа, Университет Карлсруэ (Германия). E-mail: dominik.moest@wiwi.uni-karlsruhe.de Адрес: Karlsruhe Institute of Technology, P.O. Box 6980, 76049 Karlsruhe, GermanyОбершмидт Юлия- научный сотрудник, Фраунгоферовский институт системных и инновационных исследований (Германия). E-mail: julia.oberschmidt@gmx.de Адрес: Fraunhofer-Institut für System- und Innovationsforschung ISI, Breslauer Straße 48, 76139 KarlsruheВитшель Мартин- руководитель направления «Экономика энергетики», Фраунгоферовский институт системных и инновационных исследований (Германия). E-mail: martin.wietschel@isi.fraunhofer.de Адрес: Fraunhofer-Institut für System- und Innovationsforschung ISI, Breslauer Straße 48, 76139 Karlsruhe GermanyШойфен Мартин- научный сотрудник, Институт техники высоких напряжений, Рейнско-Вестфальский технический университет Аахена (Германия). E-mail: scheufen@ifht.rwth-aachen.de Адрес: Institute for Hight Voltage Technology, Schinkelstraße 2, D-52056 AachenХеркель Себастьян- руководитель подразделения, Фраунгоферовский институт систем солнечной энергетики (Германия). E-mail: sebastian.herkel@ise.fhg.de Адрес: Heidenhofstr. 2, 79110 Freiburg, GermanyИсследования и разработки новых и усовершенствованных технологий сопровождаются высокими рисками и требуют значительных инвестиций, которые окупаются лишь в долгосрочной перспективе. Следовательно, внедрение новых или усовершенствованных энергетических технологий происходит замедленными темпами. Результаты проекта «Энергетические технологии - 2050», осуществленного в Германии в 2008 г., стали информационной основой для формирования государственной политики в области энергетических исследований и формирования приоритетов исследований неядерных источников энергии на ближайшие годы. В статье представлена методика, позволяющая оценить направления исследований в контексте многообразия политических задач и сценариев будущего. Описаны принципы определения приоритетных технологических областей. Резюмируются результаты и приводятся рекомендации по программам ИиР в каждом из тематических направлений.

The Institut für Kernphysik at Forschungszentrum Jülich

The Forschungszentrum Jülich (FZJ) pursues interdisciplinary research that aims to solve the grand challenges facing society in the fields of health, energy, and the environment, and also information technologies. In combination with its two key competencies—physics and supercomputing—work at Jülich focuses on both long-term, fundamental, and multidisciplinary contributions to science and technology as well as on specific technological applications. With a staff of about 4,500, Jülich—a member of the Helmholtz Association—is one of the largest research centers in Europe. Located south-east of the city of Jülich it is close to the center of a triangle formed by the German cities of Aachen, Düsseldorf, and Cologne.

High heat flux testing of beryllium components with improved diagnostics

Beryllium is one of the most interesting materials to be used in nuclear fusion devices due to its promising properties. However, testing of beryllium components is quite challenging because of its toxicity and the required safety procedures. Within this paper an overview of high heat flux thermal fatigue tests carried out in the electron beam facility JUDITH 2 (Juelich Divertor Test Facility in the Hot Cells) at Forschungszentrum Juelich (FZJ) on actively cooled beryllium mock ups is given. The performance of the mock ups was documented by temperature measurements as well as optical inspections before and after testing. Special attention was paid to the temperature diagnostics during the tests for two different reasons. Firstly, local overheating of the beryllium tiles, which are the proof of bonding failures, is detected by temperature measurements. Secondly, temperature information is exceptionally important to meet the required safety standards because of the toxicity of beryllium. In order to avoid evaporation of beryllium, a temperature limit for an automatic safety shut down of the electron beam facility JUDITH 2 was set to a certain value. Finally examples of the temperature distribution under different loading conditions for the beryllium mock ups are presented within this paper.

Electromagnetic modeling and subsequent structural analysis for ITER core CXRS upper port plug diagnostic structure

The upper port of the ITER vacuum vessel contains the core charge exchange spectroscopy (cCXRS) port plug diagnostic system. Electromagnetic (EM) loads caused by plasma transients are critical for the port plug. An ANSYS 3D EM model of the ITER magnet system, addressing main port plug features (conceptual design 2009), was developed by Forschungszentrum Jülich (FZJ). EM forces on main plug components have been calculated and main integral mechanical moments are represented. Two external contracts on independent global EM models were launched and are being successfully benchmarked against the FZJ model. In support of the cCXRS design its components are structurally analyzed under EM loading. Four different approaches to calculate EM loads for detailed structural models have been used and are described. One of them, called an “express” analysis, allows a prompt choice between different design solutions. The “air” elements, which should fill gaps between assembled conducting parts in the electromagnetic FE models, are neglected in this approach. This may save up to 90% of time for building and calculating complex EM models. Applicability and use of this method for small critical plug components like a fast shutter are demonstrated in this paper.

Environmental impacts of the Yangtze Three Gorges project: An overview of the Chinese-German research cooperation

The construction of the Three Gorges Dam on the Yangtze River in China has a great influence on the ecosystems involved. In order to investigate these environmental effects in the Yangtze catchment area as well as downstream of the dam, Forschungszentrum Julich has organized a research network for the Chinese and German partners. In the research fields of (1) interaction water/sediment/contaminants, (2) vegetation/biodiversity, (3) changing land use/erosion/mass movements, and (4) atmosphere, the partners have accumulated a great deal of expertise in handling major issues and also in developing models and recommendations for action. The following provides an overview of the research network and the research tasks. On the German side, five projects in research field (3) have been in operation since 2008. The results are reported in contributions by Ehret et al., Jaehnig and Cai, Schonbrodt et al., and Seeber et al.. Another five projects in research field (1) have started by September 2010. The research tasks undertaken in these five projects are presented below.

Trends in supercomputing: The European path to exascale

Recent developments in European supercomputing are reviewed covering both the latest hardware trends and the increasing difficulties faced by scientists in utilising these machines to perform large-scale numerical simulations. These challenges are reflected in the large number of international initiatives which have come into being over the last few years, founded in anticipation of exascale hardware which is foreseen within the next decade. The role of a key institution in supercomputing within these programmes is described using the example of the Jülich Supercomputing Centre (JSC), and progress in setting up its own community-oriented support units for scientific computing – Simulation Laboratories – is reported on. Finally, an assessment is made of some common grand challenges and their suitability for scaling to exaflop-scale computation.

Comparison of various anthropomorphic phantom types for in vivo measurements by means of Monte Carlo simulations

Three widely used anthropomorphic phantoms are analysed with regard to their suitability for the efficiency calibration of whole-body counters (WBCs): a Bottle Manikin Absorber (BOMAB) phantom consisting of water-filled plastic containers, a St Petersburg block phantom (Research Institute of Sea Transport Hygiene, St Petersburg) made of polyethylene bricks and a mathematical Medical Internal Radiation Dose (MIRD) phantom, each of them representing a person weighing 70 kg. The analysis was performed by means of Monte Carlo simulations with the Monte Carlo N-Particle transport code using detailed mathematical models of the phantoms and the WBC at Forschungszentrum Jülich (FZJ). The simulated peak efficiencies for the BOMAB phantom and the MIRD phantom agree very well, but the results for the St Petersburg phantom are considerably higher. Therefore, WBCs similar to that at FZJ will probably underestimate the activity of incorporated radionuclides if they are calibrated by means of a St Petersburg phantom. Finally, the results from this work are compared with the conclusions from other studies dealing with block and BOMAB phantoms.

Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

AbstractA technical description and experimental analysis of a SOFC demonstration unit is presented. The unit contains most of the primary BoP‐components of a complete SOFC system, except of air and fuel recirculation equipment or fuel system compressor. Natural gas is used as the fuel and electricity is supplied to the electric grid. A 5 kW power class planar SOFC stack from Research Centre Jülich is assembled to the demo unit and a long‐term experiment is conducted to assess the characteristic performance and durability of different components of the unit (e.g. the SOFC stack, the fuel pre‐reformer and air heat exchangers). The evolution of absolute voltage drop of the stack over time is found to be of the same magnitude when compared to short stack experiments. Thus, other system components are not observed to cause an increase in the characteristic voltage drop of the stack. Two BoP‐components, the afterburner and the power conversion unit failed to operate as designed. The performance of other BoP‐components i.e. fuel pre‐reformer and heat exchangers were satisfactory during the test run, and no significant performance loss could be measured.

Laudatio for Professor Dr. Dr. h.c. Syed M. Qaim

Professor Dr. Dr. h.c. mult. Syed Muhammad Qaim was brought up in Pakistan. He obtained both his B.Sc. (1958) and M.Sc. (1961) from the Government College and Punjab University in Lahore, Pakistan. He received his Ph.D. in Nuclear Chemistry in 1964 from Liverpool University and D.Sc. in Applied Nuclear Science in 1977 from Birmingham University in England. He then received his Habilitation in Nuclear Chemistry in 1993 from Universitat zu Koln, Germany. Upon graduation with Ph.D., Dr. Qaim joined Birmingham University as a Research Associate (1964–66). He then served as a Senior Scientific Officer, Atomic Energy Centre in Lahore, Pakistan during 1966–68. He was an Alexander von Humboldt Fellow at Johannes Gutenberg-Universitat Mainz, Germany (1968–70). Dr. Qaim then joined the Nuclear Research Centre, Julich, Germany in 1970. He spent the next 36 years at the Centre in various capacities such as a Scientist (1970–75), a Group Leader (1975–85), and a Division Leader (1985–2006) in the Institute of Nuclear Chemistry. He also served as an Acting Director (1995–96), and as the Vice-Director (1996–2006) of the Institute of Nuclear Chemistry. Additionally, since 1997 he has been a Professor of Nuclear Chemistry at Universitat zu Koln and is still teaching there. Since 2006, after his retirement, he is a Guest/Advisor at his old Institute of Nuclear Chemistry, Research Centre Julich. Furthermore, he holds a UNESCO-funded Research Professorship at the Third World Academy of Sciences (TWAS) in Trieste, Italy. Professor Qaim has very broad research interests in fundamental as well as applied aspects of nuclear chemistry, from Mossbauer spectroscopy, nuclear spectroscopy, nuclear reactions, and nuclear data to cyclotron-produced radionuclides. His fundamental work in Mossbauer spectroscopy dealt with Co incorporated in 32 different metal lattices via electrolytic deposition and high temperature diffusion. He was the first one to show that the linebroadening of the source in certain metals is caused by quadrupole splitting. The four pioneering papers published on this topic in the late sixties have become classic. His fundamental work in nuclear spectroscopy and nuclear reactions dealt with decay properties of nuclei. In the sixties Prof. Qaim discovered five new radionuclides, namely Nb, Mo, Mo, Xe and Pb, and characterized several others such as I, I, Cs, Np. In the seventies he concentrated on low-yield complex particle emission reactions, e.g. (n,t), (n,He), (n,Be) and (p,Be), which could only be studied via a combination of activation techniques with very precise radiochemical separations and low-level counting techniques as well as statistical model calculations based on the Hauser-Feshbach formalism. Prof. Qaim was awarded the Eotvos Lorand Medal of the Hungarian Physical Society in 1988 for his pioneering work in this field. In recent years, Prof. Qaim has become more interested in the fundamental aspects of the formation of isomeric Prepared by Professor Dr. A. Chatt (Halifax, Canada), Chairman of the Hevesy Medal Award Selection Panel 2008, President of the International Committee on Activation Analysis (ICAA). Narrated by Professor Dr. L. Wojnarovits (Budapest, Hungary), Co-Chairman of the 7th International Conference on Nuclear and Radiochemistry (NRC-7), Budapest, 2008. Hevesy Medal and Scroll presented by Professor Dr. Dr. h.c. Tibor Braun (Budapest, Hungary), Editor-in-Chief, Journal of Radioanalytical and Nuclear Chemistry.

High precision beam momentum determination in a synchrotron using a spin resonance method

In order to measure the mass of theη meson with high accuracy using the d p ! 3 Heη reaction, the momentum of the circulating deuteron beam in the Cooler Synchrotron COSY of the Forschungszentrum Julich has to be determined with unprecedented precision. This has been achieved by studying the spin dynamics of the polarized deuteron beam. By depolarizing the beam through the use of an artificially induced spin resonance, it was possible to evaluate its momentum p with a precision ofp/p< 10 4 for a momentum of roughly 3 GeV/c.

High heat flux testing of 12–14Cr ODS ferritic steels

The thermal performance of Fe–(12–14)Cr–2W–0.3Ti–0.3Y 2O 3 ODS reduced activation ferritic steels, which are considered as candidate first wall materials for the future fusion power reactors and were manufactured by mechanical alloying in hydrogen and hot isostatic pressing, was assessed by high heat flux (HHF) testing with the electron beam JUDITH facility at the Forschungszentrum Jülich (FZJ), Germany. An analysis of the microhardness and microstructure of the specimens was done before and after HHF tests. In general, both materials present a ferritic (α-Fe, bcc) microstructure with a wide range of grain sizes from 100 to 500 nm up to a few micrometers. The coarse grains are almost dislocation-free, while the smaller ones are surrounded by tangles of dislocations. Oxide and carbide impurities (about a few hundreds nm in size) and a high density of Y–Ti–O nano-clusters, with a mean size of about 5 nm, are also present. The microhardness, density and tensile strength of the 14Cr material are slightly larger than those of the 12Cr material. HHF tests revealed that there is no difference in thermal performance, level of degradation and erosion behaviour of 12Cr and 14Cr ODS steels. The onset of melting of the materials occurs for an energy density between 1 and 1.5 MJ/m 2. Below this value only some kind of thermal etching takes place. This is a significant improvement compared to stainless steel, for which severe plastic deformation at the material surface was observed.

The feasibility of the TRIC experiment at COSY

For the Time Reversal Invariance experiment at COSY (TRIC) that had been proposed at the Forschungszentrum Julich a novel technique for measuring total cross sections in internal experiments was developed and the achievable precision of this measuring technique was tested. The experimental idea constitutes a true P-even T-odd null test of TRI. In order to compare to the theoretical upper bound from edm measurements (Haxton and Horing, Nucl Phys A560:469, 1993), the TRI violating observable Ay,xz in proton-deuteron forward scattering has to be measured with an accuracy of 10 − 6. An internal TRI experiment can determine the total cross section via the optical theorem by measuring the forward scattering amplitude. In contrast to external experiments, the only calibrated device that is needed is a precise beam current transformer (BCT). The feasibility of an internal TRI experiment was tested at COSY in a measurement of Ay,y in p-p scattering, since these values are known. The analysis of the data showed the presence of unexpected large 1/f noise contributions, which eventually reduced the achievable accuracy by a factor 3. The origin of the 1/f noise was traced and found to be the Barkhausen noise from the ferrite-core of the BCT. A global weighted fitting technique based on a modified Wiener-Khinchin method was applied to suppress the influence of the 1/f noise.

Parallel Iterative Substructuring in Structural Mechanics

Finite Element Tearing and Interconnecting (FETI) methods are a family of nonoverlapping domain decomposition methods which have been proven to be robust and parallel scalable for a variety of elliptic partial differential equations. Here, an introduction to the classical onelevel FETI methods is given, as well as to the more recent dual-primal FETI methods and some of their variants. With the advent of modern parallel computers with thousands of processors, certain inexact components are needed in these methods to maintain scalability. An introduction to a recent class of inexact dual-primal FETI methods is presented. Scalability results for an elasticity problem using 65 536 processor cores of the JUGENE supercomputer at Forschungszentrum Julich show the potential of these methods. A hyperelastic problem from biomechanics is presented as an application of the methods to nonlinear finite element analysis.

Community-oriented support and research structures

Coordinated by the Partnership for Advanced Computing in Europe (PRACE) Europe is restructuring and strengthening its high-performance computing infrastructure with the aim to create a model HPC ecosystem. At the tip of the pyramid, up to six centres are envisaged that will operate systems of the highest performance class. The HPC Research Infrastructure (HPC-RI) will comprise European, national and regional centres. Science communities are integral partners, strong links will include Grid and Cloud users. The HPC-RI strives at providing scientists all over Europe, on the one hand, with unlimited and independent access to state-of-the-art computer resources in all performance classes and, on the other hand, with a world-class pan-European competence and support network.While the hardware-oriented buildup of the infrastructure is making progress, high-quality user support and software development in the upcoming era of unprecedented parallelism and exascale on the horizon have become the imminent challenges. This has been clearly recognized by the European Commission, who will issue calls for proposals to fund petascale software development in summer 2009. Although traditional support structures are well established in Europe's major supercomputing centres, it is questionable if these structures are able to meet the challenges of the future: in general, support structures are based on cross-disciplinary computer science and mathematics teams; disciplinary computational science support usually is given in an ad-hoc, project-oriented manner.In this paper, we describe our approach to establish a suitable support structure–Simulation Laboratories (SL). SLs are currently being established at the Jülich Supercomputing Centre of the Forschungszentrum Jülich (FZJ) and at the Steinbuch Centre for Computing (SCC) of the Karlsruhe Institute for Technology (KIT) in Germany. While SLs are community-oriented, i.e. each SL focusses on a specific community, they are structured in a strictly interdisciplinary manner, comprising mathematicians, computer scientists and technicians along with disciplinary scientists. SLs are led by a disciplinary scientist, and representatives of the respective disciplines give guidance to its operation. This concept is proposed as a model for and might become an integral element of a future pan-European HPC support and software research structure.

Precision measurements of thepp→π+pnandpp→π+dreactions: Importance of long-range and tensor force effects

Inclusive measurements of pion production in proton-proton collisions in the forward direction were undertaken at 400 and 600 MeV at the cooler synchrotron (COSY) at Forschungszentrum Julich using the Big Karl spectrograph. The high resolution in the pi(+) momentum ensured that there was an unambiguous separation of the pp ->pi(+)d/pi(+)pn channels. Using these and earlier data, the ratio of the production cross sections could be followed through the Delta region and compared with the predictions of final state interaction theory. Deviations are strongly influenced by long-range terms in the production operator and the tensor force in the final pn system. These have been investigated in a realistic pp ->pi(+)d/pi(+)pn calculation that includes S reversible arrow D channel coupling between the final nucleons. A semiquantitative understanding of the observed effects is achieved. .

Design, Manufacturing and Performance of a Pair of Superconducting Solenoids for a Neutron Spin-Echo Spectrometer at the SNS

A Neutron spin-echo (NSE) spectrometer of the next generation is under construction at the Spallation Neutron Source (SNS) in Oak Ridge, USA. A NSE spectrometer measures small velocity changes of the neutrons encoded by the neutrons spin clock at a sample while the Neutron spin precesses in large magnetic fields following Bloch's equation. This instrument will be the best of its class both with respect to resolution and dynamic range. In order to reach this ambitious goal, a large magnetic precision field integral before and after the sample is required which directly scales linearly with the resolution of the instrument. Therefore superconducting technology will be used to allow for a higher magnetic field integral. Here, we present the design, manufacturing and test performance of the solenoids which are the result of a collaboration between Julich Research Center (FZJ) and Babcock Noell GmbH (BNG). The solenoids generate an integrated magnetic flux density of 1.8 T*m and use active shielding to reduce the fringe field. The operation temperature of about 4 K is reached by means of pulse-tube coolers in order to minimize vibrations. A special feature of this magnet system is the very accurate measurement of the cold mass-position after cool-down and during operation. The accuracy of this measurement system is in the order of micrometers. This information is required for the adjustment of so called Fresnel coils outside the cryostat. Using these correction elements, a field integral homogeneity better than 10-6 T*m for different Neutron paths through one of the solenoids can be achieved.

Mechanisms of neocortical development

Mechanisms of neocortical development

Brittle Fracture Studies of Solid Oxide Fuel Cells

Solid Oxide Fuel Cells (SOFCs) with electrical efficiencies above 50 % are considered as very promising option for future decentralized energy conversion. At the Forschungszentrum Juelich (FZJ) planar SOFC stacks are currently being developed and tested at 800°C and up to 10000 h using H2 and methane as fuel. Stacks in the kW class routinely reach power densities of 700 W/cm². Typically the layered material composite of the FZJ-stack consists of cells with yttria stabilized zirconia (YSZ) electrolyte, Ni-YSZ anode and a cathode of lanthanum strontium manganite. The cells are mounted between ferritic steel interconnects. The fuel and air compartment are sealed by glass-ceramics and more recently also by metal brazes. Significant progress in reliable stack operation has been achieved over the past decade. However, problems with thermo-chemical and thermo-mechanical compatibility still remain a major challenge. To illustrate the complexity of material interactions in SOFCs, selected problems related to mechanical failure processes are presented. The role of residual stresses is addressed and fracture phenomena of cell and sealant are described in greater detail.