ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS

International Nuclear Information System (INIS)

Wei, J.; Macek, R.J.

2002-01-01

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures

Simulating electron clouds in heavy-ion accelerators

International Nuclear Information System (INIS)

Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Stoltz, P.; Veitzer, S.

2005-01-01

Contaminating clouds of electrons are a concern for most accelerators of positively charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly magnetized, weakly magnetized, and unmagnetized. The approach to such self-consistency is described, and in particular a scheme for interpolating between full-orbit (Boris) and drift-kinetic particle pushes that enables electron time steps long compared to the typical gyroperiod in the magnets. Tests and applications are presented: simulation of electron clouds produced by three different kinds of sources indicates the sensitivity of the cloud shape to the nature of the source; first-of-a-kind self-consistent simulation of electron-cloud experiments on the high-current experiment [L. R. Prost, P. A. Seidl, F. M. Bieniosek, C. M. Celata, A. Faltens, D. Baca, E. Henestroza, J. W. Kwan, M. Leitner, W. L. Waldron, R. Cohen, A. Friedman, D. Grote, S. M. Lund, A. W. Molvik, and E. Morse, 'High current transport experiment for heavy ion inertial fusion', Physical Review Special Topics, Accelerators and Beams 8, 020101 (2005)], at Lawrence Berkeley National Laboratory, in which the machine can be flooded with electrons released by impact of the ion beam on an end plate, demonstrate the ability to reproduce key features of the ion-beam phase space; and simulation of a two-stream instability of thin beams in a magnetic field demonstrates the ability of the large-time-step mover to accurately calculate the instability

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS.

Energy Technology Data Exchange (ETDEWEB)

WEI,J.; MACEK,R.J.

2002-04-14

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures.

Electron cloud observations at the ISIS Proton Synchrotron

CERN Document Server

Pertica, A.

2013-04-22

The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.

Theory and measurement of the electron cloud effect

CERN Document Server

Harkay, K C

1999-01-01

Photoelectrons produced through the interaction of synchrotron radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SEs) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a runaway condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models ...

Cyclotron Resonances in Electron Cloud Dynamics

International Nuclear Information System (INIS)

Celata, C.M.; Furman, M.A.; Vay, J.L.; Grote, D.P.; Ng, J.T.; Pivi, M.F.; Wang, L.F.

2009-01-01

A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where l b c , (l b = bunch duration, ω c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ∼ 3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined density 'stripes' of multipactoring found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations, the reason for the bunch-length dependence, and details of the dynamics will be discussed

Electron Cloud Parameterization Studies in the LHC

CERN Document Server

Dominguez, O; Baglin, V; Bregliozzi, G; Jimenez, J M; Metral, E; Rumolo, G; Schulte, D; Zimmermann, F

2011-01-01

During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud, defined about ten years ago, relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. most importantly, the secondary emission yield δmax; 2. the incident electron energy at which the yield is maximum, ε_max; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall, R. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmarking of measurements and simulations is used to infer the s...

Electron cloud buildup studies for the LHC

CERN Document Server

AUTHOR|(CDS)2160803; Boine-Frankenheim, Oliver

Electron clouds can develop in accelerators operating with positively charged particles. The con- sequences of e-cloud related effects are very important for the operation of the Large Hadron Collider (LHC) at CERN, and for the design of future accelerators including the LHC luminosity upgrade (HL-LHC). High electron densities are generated by an interaction between the beam and the confining chamber. Primary electrons, that can be generated through various mecha- nisms, are accelerated by the beam and impinge on the chamber walls, thereby extracting more electrons from the material. Furthermore they also deposit their kinetic energy in the process, which has to be compensated by the cooling system. Especially in cryogenic environments, as it is the case for a large part of the LHC, high heat loads can pose a serious problem. In order to improve the understanding of the electron cloud, simulation studies are performed with the code PyECLOUD, developed at CERN. The work of the first half of the project is desc...

Computation of electron cloud diagnostics and mitigation in the main injector

International Nuclear Information System (INIS)

Veitzer, S A; Cary, J R; Stoltz, P H; LeBrun, P; Spentzouris, P; Amundson, J F

2009-01-01

High-performance computations on Blue Gene/P at Argonne's Leadership Computing Facility have been used to determine phase shifts induced in injected RF diagnostics as a function of electron cloud density in the Main Injector. Inversion of the relationship between electron cloud parameters and induced phase shifts allows us to predict electron cloud density and evolution over many bunch periods. Long time-scale simulations using Blue Gene have allowed us to measure cloud evolution patterns under the influence of beam propagation with realistic physical parameterizations, such as elliptical beam pipe geometry, self-consistent electromagnetic fields, space charge, secondary electron emission, and the application of arbitrary external magnetic fields. Simultaneously, we are able to simulate the use of injected microwave diagnostic signals to measure electron cloud density, and the effectiveness of various mitigation techniques such as surface coating and the application of confining magnetic fields. These simulations provide a baseline for both RF electron cloud diagnostic design and accelerator fabrication in order to measure electron clouds and mitigate the adverse effects of such clouds on beam propagation.

A New Electronic Commerce Architecture in the Cloud

OpenAIRE

Guigang Zhang; Chao Li; Sixin Xue; Yuenan Liu; Yong Zhang; Chunxiao Xing

2012-01-01

In this paper, the authors propose a new electronic commerce architecture in the cloud that satisfies the requirements of the cloud. This architecture includes five technologies, which are the massive EC data storage technology in the cloud, the massive EC data processing technology in the cloud, the EC security management technology in the cloud, OLAP technology for EC in the cloud, and active EC technology in the cloud. Finally, a detailed discussion of future trends for EC in the cloud env...

DAФNE Operation with Electron-Cloud-Clearing Electrodes

CERN Document Server

Alesini, D; Gallo, A; Guiducci, S; Milardi, C; Stella, A; Zobov, Mikhail; De Santis, S; Demma, Theo; Raimondi, P

2013-01-01

The effects of an electron cloud (e-cloud) on beam dynamics are one of the major factors limiting performances of high intensity positron, proton, and ion storage rings. In the electron-positron collider DAΦNE, namely, a horizontal beam instability due to the electron-cloud effect has been identified as one of the main limitations on the maximum stored positron beam current and as a source of beam quality deterioration. During the last machine shutdown in order to mitigate such instability, special electrodes have been inserted in all dipole and wiggler magnets of the positron ring. It has been the first installation all over the world of this type since long metallic electrodes have been installed in all arcs of the collider positron ring and are currently used during the machine operation in collision. This has allowed a number of unprecedented measurements (e-cloud instabilities growth rate, transverse beam size variation, tune shifts along the bunch train) where the e-cloud contribution is clearly eviden...

Electron-cloud measurements and simulations for the APS

International Nuclear Information System (INIS)

Furman, M.A.; Pivi, M.; Harkay, K.C.; Rosenberg, R.A.

2001-01-01

We compare experimental results with simulations of the electron cloud effect induced by a positron beam at the APS synchrotron light source at ANL, where the electron cloud effect has been observed and measured with dedicated probes. We find good agreement between simulations and measurements for reasonable values of certain secondary electron yield (SEY) parameters, most of which were extracted from recent bench measurements at SLAC

Measurement of Electron Cloud Effects in SPS

CERN Document Server

Jiménez, J M

2004-01-01

The electron cloud is not a new phenomenon, indeed, it was observed already in other machines like the proton storage rings in BINP Novosibirsk or in the Intersecting Storage Ring (ISR) at CERN. Inside an accelerator beam pipe, the electrons can collectively and coherently interact with the beam potential and degrade the performance of the accelerators operating with intense positively charged bunched beams. In the LHC, electron multipacting is expected to take place in the cold and warm beam pipe due to the presence of the high intensities bunched beams, creating an electron cloud. The additional heat load induced by the electron cloud onto the LHC beam screens of the cold magnets of the LHC bending sections (the arcs represent ~21 km in length) was, and is still, considered as one of the main possible limitation of LHC performances. Since 1997 and in parallel with the SPS studies with LHC-type beams, measurements in other machines or in the laboratory have been made to provide the input parameters required ...

National electronic medical records integration on cloud computing system.

Science.gov (United States)

Mirza, Hebah; El-Masri, Samir

2013-01-01

Few Healthcare providers have an advanced level of Electronic Medical Record (EMR) adoption. Others have a low level and most have no EMR at all. Cloud computing technology is a new emerging technology that has been used in other industry and showed a great success. Despite the great features of Cloud computing, they haven't been utilized fairly yet in healthcare industry. This study presents an innovative Healthcare Cloud Computing system for Integrating Electronic Health Record (EHR). The proposed Cloud system applies the Cloud Computing technology on EHR system, to present a comprehensive EHR integrated environment.

Simulation of wake potentials induced by relativistic proton bunches in electron clouds

Energy Technology Data Exchange (ETDEWEB)

Petrov, Fedor; Boine-Frankenheim, Oliver; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder (TEMF)

2012-07-01

Electron clouds limit the intensity of modern high intensity hadron accelerators. Presently electron clouds are the main limiting factor for the LHC operation with 25 ns bunch trains. The bunches passing through an electron cloud induce a wake field. When the electron cloud density exceeds a certain threshold beam instabilities occur. The presence of electron clouds results in a shift of the synchronous phase, which increases if the bunch spacing is reduced. For LHC and SPS conditions we compare the longitudinal electron cloud wake potentials and stopping powers obtained using a simplified 2D electrostatic Particle-in-Cell code with fully electromagnetic simulations using VORPAL. In addition we analyze the wake fields induced by displaced or tilted bunches.

Electron-cloud effects in high-luminosity colliders

Energy Technology Data Exchange (ETDEWEB)

Zimmermann, F.

1998-01-01

Electron-cloud instabilities are expected to be important in most high-luminosity double-ring colliders. In this report, the author describes a few parameter regimes and some critical parameter dependences of this type of instability, and illustrate these with simulation results for the PEP-II and KEK B factories, the LHC, the VLHC, and DAPHNE. In addition, the author studies the possibility and the potential impact of an electron cloud in the interaction region.

Electron Cloud at Low Emittance in CesrTA

CERN Document Server

Palmer, Mark; Billing, Michael; Calvey, Joseph; Conolly, Christopher; Crittenden, James; Dobbins, John; Dugan, Gerald; Eggert, Nicholas; Fontes, Ernest; Forster, Michael; Gallagher, Richard; Gray, Steven; Greenwald, Shlomo; Hartill, Donald; Hopkins, Walter; Kreinick, David; Kreis, Benjamin; Leong, Zhidong; Li, Yulin; Liu, Xianghong; Livezey, Jesse; Lyndaker, Aaron; Makita, Junki; McDonald, Michael; Medjidzade, Valeri; Meller, Robert; O'Connell, Tim; Peck, Stuart; Peterson, Daniel; Ramirez, Gabriel; Rendina, Matthew; Revesz, Peter; Rider, Nate; Rice, David; Rubin, David; Sagan, David; Savino, James; Schwartz, Robert; Seeley, Robert; Sexton, James; Shanks, James; Sikora, John; Smith, Eric; Strohman, Charles; Williams, Heather; Antoniou, Fanouria; Calatroni, Sergio; Gasior, Marek; Jones, Owain Rhodri; Papaphilippou, Yannis; Pfingstner, Juergen; Rumolo, Giovanni; Schmickler, Hermann; Taborelli, Mauro; Asner, David; Boon, Laura; Garfinkel, Arthur; Byrd, John; Celata, Christine; Corlett, John; De Santis, Stefano; Furman, Miguel; Jackson, Alan; Kraft, Rick; Munson, Dawn; Penn, Gregory; Plate, David; Venturini, Marco; Carlson, Benjamin; Demma, Theo; Dowd, Rohan; Flanagan, John; Jain, Puneet; Kanazawa, Ken-ichi; Kubo, Kiyoshi; Ohmi, Kazuhito; Sakai, Hiroshi; Shibata, Kyo; Suetsugu, Yusuke; Tobiyama, Makoto; Gonnella, Daniel; Guo, Weiming; Harkay, Katherine; Holtzapple, Robert; Jones, James; Wolski, Andrzej; Kharakh, David; Ng, Johnny; Pivi, Mauro; Wang, Lanfa; Ross, Marc; Tan, Cheng-Yang; Zwaska, Robert; Schachter, Levi; Wilkinson, Eric

2010-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deployed and tested and their effectiveness is discussed. Measurements of the electron cloud’s effect on the beam under a range of conditions are discussed along with the simulations being used to quantitatively understand these results

Studies of dynamics of electron clouds in STAR silicon drift detectors

CERN Document Server

Bellwied, R; Brandon, N; Caines, H; Chen, W; Dimassimo, D; Dyke, H; Hall, J R; Hardtke, D; Hoffmann, G W; Humanic, T J; Kotova, A I; Kotov, I V; Kraner, H W; Li, Z; Lynn, D; Middelkamp, P; Ott, G; Pandey, S U; Pruneau, C A; Rykov, V L; Schambach, J; Sedlmeir, J; Sugarbaker, E R; Takahashi, J; Wilson, W K

2000-01-01

The dynamics of electrons generated in silicon drift detectors was studied using an IR LED. Electrons were generated at different drift distances. In this way, the evolution of the cloud as a function of drift time was measured. Two methods were used to measure the cloud size. The method of cumulative functions was used to extract the electron cloud profiles. Another method obtains the cloud width from measurements of the charge collected on a single anode as a function of coordinate of the light spot. The evolution of the electron cloud width with drift time is compared with theoretical calculations. Experimental results agreed with theoretical expectations.

Emittance growth induced by electron cloud in proton storage rings

CERN Document Server

Benedetto, Elena; Coppa, G

2006-01-01

In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

Electron-Cloud Wake Fields

CERN Document Server

Rumolo, Giovanni

2002-01-01

The electron cloud gives rise to coherent and incoherent single-bunch wake fields, both in the longitudinal and in the transverse direction, and to coherent coupled-bunch wakes. These wake fields can be computed using the simulation programs ECLOUD and HEADTAIL developed at CERN. We present the wake fields simulated for the LHC beam in the CERN SPS and at injection into the LHC in different magnetic field configurations (field-free region, dipole, and solenoid), where the magnetic field affects both the elec-tron motion during a bunch passage and the overall electron distribution in the beam pipe.

Final Report for 'Modeling Electron Cloud Diagnostics for High-Intensity Proton Accelerators'

International Nuclear Information System (INIS)

Veitzer, Seth A.

2009-01-01

Electron clouds in accelerators such as the ILC degrade beam quality and limit operating efficiency. The need to mitigate electron clouds has a direct impact on the design and operation of these accelerators, translating into increased cost and reduced performance. Diagnostic techniques for measuring electron clouds in accelerating cavities are needed to provide an assessment of electron cloud evolution and mitigation. Accurate numerical modeling of these diagnostics is needed to validate the experimental techniques. In this Phase I, we developed detailed numerical models of microwave propagation through electron clouds in accelerating cavities with geometries relevant to existing and future high-intensity proton accelerators such as Project X and the ILC. Our numerical techniques and simulation results from the Phase I showed that there was a high probability of success in measuring both the evolution of electron clouds and the effects of non-uniform electron density distributions in Phase II.

Theory and measurement of the electron cloud effect

International Nuclear Information System (INIS)

Harkey, K. C.

1999-01-01

Photoelectrons produced through the interaction of synchrotrons radiation and the vacuum chamber walls can be accelerated by a charged particle beam, acquiring sufficient energy to produce secondary electrons (SES) in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, a run-away condition can develop. In addition to the SEY, the degree of amplification depends on the beam intensity and temporal distribution. As the electron cloud builds up along a train of stored bunches, a transverse perturbation of the head bunch can be communicated to trailing bunches in a wakefield-like interaction with the cloud. The electron cloud effect is especially of concern for the high-intensity PEP-II (SLAC) and KEK B-factories and at the Large Hadron Collider (LHC) at CERN. An initiative was undertaken at the Advanced Photon Source (APS) storage ring to characterize the electron cloud in order to provide realistic limits on critical input parameters in the models and improve their predictive capabilities. An intensive research program was undertaken at CERN to address key issues relating to the LHC. After giving an overview, the recent theoretical and experimental results from the APS and the other laboratories will be discussed

Impact of Microwaves on the Electron Cloud and Incoherent Effects

CERN Document Server

Decker, Franz Josef; Zimmermann, Frank

2002-01-01

We consider the use of microwaves for manipulating the electron cloud, describing an exploratory experiment at PEP-II as well as computer simulations of the electron cloud build-up in the presence of a microwave for an LHC dipole. We then show that the incoherent effects of the electron cloud - energy loss and transverse emittance growth due to scattering of the electrons - are negligible. This suggests that the disturbance of the coherent motion may be another possible application of microwaves, which could prevent beam emittance growth and beam loss.

Recommendation for Mitigations of the Electron Cloud Instability in the ILC

International Nuclear Information System (INIS)

Pivi, Mauro

2011-01-01

Electron cloud has been identified as one of the highest priority issues for the international Linear Collider (ILC) Damping Rings (DR). An electron cloud Working Group (WG) has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions to the electron cloud formation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2 km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. In addition, a number of items requiring further investigation were identified during the discussions at the Cornell meeting and studies will be carried out at CesrTA, a test accelerator dedicated to electron cloud studies, and other institutions.

Electron Cloud Build Up and Instability in the CLIC Damping Rings

CERN Document Server

Rumolo, G; Papaphilippou, Y

2008-01-01

Electron cloud can be formed in the CLIC positron damping ring and cause intolerable tune shift and beam instability. Build up simulations with the Faktor2 code, developed at CERN, have been done to predict the cloud formation in the arcs and wigglers of the damping rings. HEADTAIL simulations have been used to study the effect of this electron cloud on the beam and assess the thresholds above which the electron cloud instability would set in.

Electron cloud sizes in gas-filled detectors

International Nuclear Information System (INIS)

Boggende, A.J.F. den; Schrijver, C.J.

1984-01-01

Electron cloud sizes have been calculated for gas mixtures containing Ar, Xe, CO 2 , CH 4 , and N 2 for drifts through a constant electric field. The transport coefficients w and D/μ are in good agreement with experimental data of various sources for pure gases. Results of measurements, also performed in this work, for Ar+CO 2 , Ar+CH 4 , and Ar+Xe+CO 2 mixtures are in fair agreement with the calculated cloud sizes. For a large number of useful gas mixtures calculated electron cloud sizes are presented and discussed, most of which are given for the first time. A suggestion is made for an optimal gas mixture for an X-ray position sensitive proportional counter for medium and low energies. (orig.)

Relation between parameters of self-sustaining magnetically confined electron cloud and external conditions

International Nuclear Information System (INIS)

Yu Qingchang

1991-01-01

On the basis of the fluid theory of the axisymmetrical self-sustaining magnetically confined electron clouds an approximate analytical method is developed. By means of this method the relations between the parameters of this type of electron cloud and external conditions are studied. The parameters include electron density, electron temperature, drift angular frequency of electrons, radius of the electron cloud and electric potential at the centre of the electron cloud. They depend on the voltage, magnetic induction, pressure, electromagnetic field distribution in the confinement device and parameters of electron-atom collisions

Dynamic electronic institutions in agent oriented cloud robotic systems.

Science.gov (United States)

Nagrath, Vineet; Morel, Olivier; Malik, Aamir; Saad, Naufal; Meriaudeau, Fabrice

2015-01-01

The dot-com bubble bursted in the year 2000 followed by a swift movement towards resource virtualization and cloud computing business model. Cloud computing emerged not as new form of computing or network technology but a mere remoulding of existing technologies to suit a new business model. Cloud robotics is understood as adaptation of cloud computing ideas for robotic applications. Current efforts in cloud robotics stress upon developing robots that utilize computing and service infrastructure of the cloud, without debating on the underlying business model. HTM5 is an OMG's MDA based Meta-model for agent oriented development of cloud robotic systems. The trade-view of HTM5 promotes peer-to-peer trade amongst software agents. HTM5 agents represent various cloud entities and implement their business logic on cloud interactions. Trade in a peer-to-peer cloud robotic system is based on relationships and contracts amongst several agent subsets. Electronic Institutions are associations of heterogeneous intelligent agents which interact with each other following predefined norms. In Dynamic Electronic Institutions, the process of formation, reformation and dissolution of institutions is automated leading to run time adaptations in groups of agents. DEIs in agent oriented cloud robotic ecosystems bring order and group intellect. This article presents DEI implementations through HTM5 methodology.

Changing in tool steels wear resistance under electron irradiation

International Nuclear Information System (INIS)

Braginskaya, A.E.; Manin, V.N.; Makedonskij, A.V.; Mel'nikova, N.A.; Pakchanin, L.M.; Petrenko, P.V.

1983-01-01

The tool steels and alloys wear resistance under dry friction after electron irradiation has been studied. Electron irradiation of a wide variety of steels is shown to increase wear resistance. In this case phase composition and lattice parameters changes are observed both in matrix and carbides. The conclusion is drawn that an appreciable increase of steel wear resistance under electron irradiation can be explained both by carbide phase volume gain and changes in it's composition and the formation of carbide phase submicroscopic heterogeneities and, possibly, complexes of defects

Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

International Nuclear Information System (INIS)

Holtzapple, R.L.; Campbell, R.C.; McArdle, K.E.; Miller, M.I.; Totten, M.M.; Tucker, S.L.; Billing, M.G.; Dugan, G.F.; Ramirez, G.A.; Sonnad, K.G.; Williams, H.A.; Flanagan, J.; Palmer, M.A.

2016-01-01

Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions

Trapping of Electron Cloud LLC/Cesrta Quadrupole and Sextupole Magnets

International Nuclear Information System (INIS)

Wang, L.

2011-01-01

The Cornell Electron Storage Ring (CESR) has been reconfigured as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R and D (1). One of the primary goals of the CesrTA program is to investigate the interaction of the electron cloud with low emittance positron beam to explore methods to suppress the electron cloud, develop suitable advanced instrumentation required for these experimental studies and benchmark predictions by simulation codes. This paper reports the simulation of the electron-cloud formation in CESRTA and ILC quadrupole and sextupole magnets using the 3D code CLOUDLAND. We found that electrons can be trapped with a long lifetime in a quadrupole and sextupole magnet due to the mirror field trapping mechanism. We study the effects of magnet strength, bunch current, ante-chamber effect, bunch spacing effect and secondary emission yield (SEY) in great detail. The development of an electron cloud in magnets is the main concern where a weak solenoid field is not effective. Quadrupole and sextupole magnets have mirror field configurations which may trap electrons by the mirror field trapping mechanism (2). Fig.1 shows the orbit of a trapped electron in a quadrupole magnet. The electron makes gyration motion (called transverse motion) and also moves along the field line (called longitudinal motion). At the mirror point (middle of the field line), there is a maximum longitudinal energy and minimum transverse energy. When the electron moves away from the mirror point, its longitudinal energy reduces and the transverse energy increases as the magnetic field increases. If the magnetic field is strong enough, the longitudinal energy becomes zero at one point and then the electron is turned back by the strong field. Note that the electrons are trapped in the region near the middle of the field lines. Although all quadrupole and sextupole magnets can trap electrons in principle, the

Measurement of Electron Clouds in Large Accelerators by Microwave Dispersion

Energy Technology Data Exchange (ETDEWEB)

De Santis, S.; Byrd, J.M.; /LBL, Berkeley; Caspers, F.; /CERN; Krasnykh, A.; /SLAC; Kroyer, T.; /CERN; Pivi, M.T.F.; /SLAC; Sonnad, K.G.; /LBL, Berkeley

2008-03-19

Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a 50 m section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center.

Electron temperatures within magnetic clouds between 2 and 4 AU: Voyager 2 observations

Science.gov (United States)

Sittler, E. C.; Burlaga, L. F.

1998-08-01

We have performed an analysis of Voyager 2 plasma electron observations within magnetic clouds between 2 and 4 AU identified by Burlaga and Behannon [1982]. The analysis has been confined to three of the magnetic clouds identified by Burlaga and Behannon that had high-quality data. The general properties of the plasma electrons within a magnetic cloud are that (1) the moment electron temperature anticorrelates with the electron density within the cloud, (2) the ratio Te/Tp tends to be >1, and (3) on average, Te/Tp~7.0. All three results are consistent with previous electron observations within magnetic clouds. Detailed analyses of the core and halo populations within the magnetic clouds show no evidence of either an anticorrelation between the core temperature TC and the electron density Ne or an anticorrelation between the halo temperature TH and the electron density. Within the magnetic clouds the halo component can contribute more than 50% of the electron pressure. The anticorrelation of Te relative to Ne can be traced to the density of the halo component relative to the density of the core component. The core electrons dominate the electron density. When the density goes up, the halo electrons contribute less to the electron pressure, so we get a lower Te. When the electron density goes down, the halo electrons contribute more to the electron pressure, and Te goes up. We find a relation between the electron pressure and density of the form Pe=αNeγ with γ~0.5.

Electron-cloud build-up in hadron machines

International Nuclear Information System (INIS)

Furman, M.A.

2004-01-01

The first observations of electron-proton coupling effect for coasting beams and for long-bunch beams were made at the earliest proton storage rings at the Budker Institute of Nuclear Physics (BINP) in the mid-60's [1]. The effect was mainly a form of the two-stream instability. This phenomenon reappeared at the CERN ISR in the early 70's, where it was accompanied by an intense vacuum pressure rise. When the ISR was operated in bunched-beam mode while testing aluminum vacuum chambers, a resonant effect was observed in which the electron traversal time across the chamber was comparable to the bunch spacing [2]. This effect (''beam-induced multipacting''), being resonant in nature, is a dramatic manifestation of an electron cloud sharing the vacuum chamber with a positively-charged beam. An electron-cloud-induced instability has been observed since the mid-80's at the PSR (LANL) [3]; in this case, there is a strong transverse instability accompanied by fast beam losses when the beam current exceeds a certain threshold. The effect was observed for the first time for a positron beam in the early 90's at the Photon Factory (PF) at KEK, where the most prominent manifestation was a coupled-bunch instability that was absent when the machine was operated with an electron beam under otherwise identical conditions [4]. Since then, with the advent of ever more intense positron and hadron beams, and the development and deployment of specialized electron detectors [5-9], the effect has been observed directly or indirectly, and sometimes studied systematically, at most lepton and hadron machines when operated with sufficiently intense beams. The effect is expected in various forms and to various degrees in accelerators under design or construction. The electron-cloud effect (ECE) has been the subject of various meetings [10-15]. Two excellent reviews, covering the phenomenology, measurements, simulations and historical development, have been recently given by Frank Zimmermann [16

Shielded button electrodes for time-resolved measurements of electron cloud buildup

International Nuclear Information System (INIS)

Crittenden, J.A.; Billing, M.G.; Li, Y.; Palmer, M.A.; Sikora, J.P.

2014-01-01

We report on the design, deployment and signal analysis for shielded button electrodes sensitive to electron cloud buildup at the Cornell Electron Storage Ring. These simple detectors, derived from a beam-position monitor electrode design, have provided detailed information on the physical processes underlying the local production and the lifetime of electron densities in the storage ring. Digitizing oscilloscopes are used to record electron fluxes incident on the vacuum chamber wall in 1024 time steps of 100 ps or more. The fine time steps provide a detailed characterization of the cloud, allowing the independent estimation of processes contributing on differing time scales and providing sensitivity to the characteristic kinetic energies of the electrons making up the cloud. By varying the spacing and population of electron and positron beam bunches, we map the time development of the various cloud production and re-absorption processes. The excellent reproducibility of the measurements also permits the measurement of long-term conditioning of vacuum chamber surfaces

Simulation of the electron cloud density in BEPC II

International Nuclear Information System (INIS)

Liu Yudong; Guo Zhiyuan; Wang Jiuqing

2004-01-01

Electron Cloud Instability (ECI) may take place in positron storage ring when the machine is operated with multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPC II, a program has been developed. With the code, authors can calculate the electron density in the chamber with different length of antechamber and the different secondary electron yield respectively. By the simulation, the possibility to put clearing electrodes in the chamber to reduce the electron density in the central region of the chamber is investigated. The simulation provides meaningful and important results for the BEPC II project and electron cloud instability research

Low Secondary Electron Yield Carbon Coatings for Electron Cloud Mitigation in Modern Particle Accelerators

CERN Document Server

Yin Vallgren, Christina; Taborelli, Mauro

2011-01-01

In order to upgrade the Large Hadron Collider (LHC) performance to be oriented towards higher energies and higher intensities in the future, a series of improvements of the existing LHC injectors is planned to take place over the next few years. Electron cloud effects are expected to be enhanced and play a central role in limiting the performance of the machines of the CERN complex. Electron cloud phenomena in beam pipes are based on electron multiplication and can be sufficiently suppressed if the Secondary Electron Yield (SEY) of the surface of the beam pipes is lower than unity. The goal of this work is to find and study a thin film coating with reliably low initial Secondary Electron Yield (SEY), which does not require bake-out or conditioning in situ with photons, is robust again air exposure and can easily be applied in the beam pipes of accelerators. In this work, amorphous carbon (a-C) thin films have been prepared by DC magnetron sputtering for electron cloud mitigation and antimultipactor applicatio...

Experimental studies of stable confined electron clouds using Gabor lenses

CERN Document Server

Meusel, O.; Glaeser, B.; Schulte, K.

2013-04-22

Based on the idea of D. Gabor [1] space charge lenses are under investigation to be a powerful focussing device for intense ion beams. A stable confined electron column is used to provide strong radially symmetric electrostatic focussing, e.g. for positively charged ion beams. The advantages of Gabor lenses are a mass independent focussing strength, space charge compensation of the ion beam and reduced magnetic or electric fields compared to conventional focussing devices. Collective phenomena of the electron cloud result in aberrations and emittance growth of the ion beam. The knowledge of the behaviour of the electron cloud prevents a decrease of the beam brilliance. Numerical models developed to describe the electron confinement and dynamics within a Gabor lens help to understand the interaction of the ion beam with the electron column and show the causes of non-neutral plasma instabilities. The diagnosis of the electron cloud properties helps to evaluate the numerical models and to investigate the influen...

Electron-Cloud Simulation and Theory for High-Current Heavy-Ion Beams

International Nuclear Information System (INIS)

Cohen, R; Friedman, A; Lund, S; Molvik, A; Lee, E; Azevedo, T; Vay, J; Stoltz, P; Veitzer, S

2004-01-01

Stray electrons can arise in positive-ion accelerators for heavy ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary- electron emission. We summarize the distinguishing features of electron cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds. We also present results from several ingredients in this capability: (1) We calculate the electron cloud produced by electron desorption from computed beam-ion loss, which illustrates the importance of retaining ion reflection at the walls. (2) We simulate of the effect of specified electron cloud distributions on ion beam dynamics. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing mode frequencies, the centroid and shape perturbations can also have significant impact. We identify an instability associated with a resonance between the beam-envelope ''breathing'' mode and the electron perturbation. We estimate its growth rate, which is moderate (compared to the reciprocal of a typical pulse duration). One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations. (3) We report first results from a long-timestep algorithm for electron dynamics, which holds promise for efficient simultaneous solution of electron and ion dynamics

Electron-cloud simulation and theory for high-current heavy-ion beams

Directory of Open Access Journals (Sweden)

R. H. Cohen

2004-12-01

Full Text Available Stray electrons can arise in positive-ion accelerators for heavy-ion fusion or other applications as a result of ionization of ambient gas or gas released from walls due to halo-ion impact, or as a result of secondary-electron emission. We summarize the distinguishing features of electron-cloud issues in heavy-ion-fusion accelerators and a plan for developing a self-consistent simulation capability for heavy-ion beams and electron clouds (also applicable to other accelerators. We also present results from several ingredients in this capability. (1 We calculate the electron cloud produced by electron desorption from computed beam-ion loss, which illustrates the importance of retaining ion reflection at the walls. (2 We simulate the effect of specified electron-cloud distributions on ion beam dynamics. We consider here electron distributions with axially varying density, centroid location, or radial shape, and examine both random and sinusoidally varying perturbations. We find that amplitude variations are most effective in spoiling ion beam quality, though for sinusoidal variations which match the natural ion beam centroid oscillation or breathing-mode frequencies, the centroid and shape perturbations can also have significant impact. We identify an instability associated with a resonance between the beam-envelope “breathing” mode and the electron perturbation. We estimate its growth rate, which is moderate (compared to the reciprocal of a typical pulse duration. One conclusion from this study is that heavy-ion beams are surprisingly robust to electron clouds, compared to a priori expectations. (3 We report first results from a long-time-step algorithm for electron dynamics, which holds promise for efficient simultaneous solution of electron and ion dynamics.

Simulations of the electron cloud buildup and its influence on the microwave transmission measurement

Energy Technology Data Exchange (ETDEWEB)

Haas, Oliver Sebastian, E-mail: o.haas@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Boine-Frankenheim, Oliver [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, 64291 Darmstadt (Germany); Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany); Petrov, Fedor [Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Schlossgartenstraße 8, 64289 Darmstadt (Germany)

2013-11-21

An electron cloud density in an accelerator can be measured using the Microwave Transmission (MWT) method. The aim of our study is to evaluate the influence of a realistic, nonuniform electron cloud on the MWT. We conduct electron cloud buildup simulations for beam pipe geometries and bunch parameters resembling roughly the conditions in the CERN SPS. For different microwave waveguide modes the phase shift induced by a known electron cloud density is obtained from three different approaches: 3D Particle-In-Cell (PIC) simulation of the electron response, a 2D eigenvalue solver for waveguide modes assuming a dielectric response function for cold electrons, a perturbative method assuming a sufficiently smooth density profile. While several electron cloud parameters, such as temperature, result in minor errors in the determined density, the transversely inhomogeneous density can introduce a large error in the measured electron density. We show that the perturbative approach is sufficient to describe the phase shift under realistic electron cloud conditions. Depending on the geometry of the beam pipe, the external magnetic field configuration and the used waveguide mode, the electron cloud density can be concentrated at the beam pipe or near the beam pipe center, leading to a severe over- or underestimation of the electron density. -- Author-Highlights: •Electron cloud distributions are very inhomogeneous, especially in dipoles. •These inhomogeneities affect the microwave transmission measurement results. •Electron density might be over- or underestimated, depending on setup. •This can be quantified with several models, e.g. a perturbative approach.

Model of the electron acceleration in the clouds of radio galaxies

International Nuclear Information System (INIS)

Fedorenko, V.N.

1980-01-01

The mechanism of electron turbulent acceleration in the clouds of radio galaxies is studied. It is suggested that clouds of radio galaxies are continuously filled by relativistic matter. A self-consistent turbulent acceleration regime in the clouds of radio galaxies is shown to be realized. The synchrotron energetic losses of the ultra-relativistic electrons are compensated by the turbulent acceleration due to Langmuir and Alfven waves. The source of Langmuir waves turbulence is the relativistic matter emanating from the galaxy nuclei and relaxating within the ''hot spots'' of the clouds

Electron cloud diagnostics in use at the Los Alamos PSR

International Nuclear Information System (INIS)

Macek, R. J.; Browman, A.; Borden, M.; Fitzgerald, D.; Wang, T. S.; Zaugg, T.; Harkay, K.; Rosenberg, R.

2003-01-01

A variety of electron cloud diagnostics have been deployed at the Los Alamos Proton Storage Ring (PSR) to detect, measure, and characterize the electron cloud generated in this high intensity, long bunch accumulator ring. These include a version of the ANL-developed retarding field analyzers (RFA) augmented with LANL-developed electronics, a variant of the RFA denoted as the electron sweeping diagnostic (ESD), biased collection plates, and gas pulse measuring devices. The designs and experience with the performance and applicability to PSR are discussed

Electron cloud in the CERN accelerators (PS, SPS, LHC)

International Nuclear Information System (INIS)

Iadarola, G; Rumolo, G

2013-01-01

Several indicators have pointed to the presence of an Electron Cloud (EC) in some of the CERN accelerators, when operating with closely spaced bunched beams. In particular, spurious signals on the pick ups used for beam detection, pressure rise and beam instabilities were observed at the Proton Synchrotron (PS) during the last stage of preparation of the beams for the Large Hadron Collider (LHC), as well as at the Super Proton Synchrotron (SPS). Since the LHC has started operation in 2009, typical electron cloud phenomena have appeared also in this machine, when running with trains of closely packed bunches (i.e. with spacings below 150ns). Beside the above mentioned indicators, other typical signatures were seen in this machine (due to its operation mode and/or more refined detection possibilities), like heat load in the cold dipoles, bunch dependent emittance growth and degraded lifetime in store and bunch-by-bunch stable phase shift to compensate for the energy loss due to the electron cloud. An overview of the electron cloud status in the different CERN machines (PS, SPS, LHC) will be presented in this paper, with a special emphasis on the dangers for future operation with more intense beams and the necessary countermeasures to mitigate or suppress the effect. (author)

Electron-Cloud Build-up in the FNAL Main Injector

International Nuclear Information System (INIS)

Furman, M.A.

2007-01-01

We present a summary on ongoing simulation results for the electron-cloud buildup in the context of the proposed FNAL Main Injector (MI) intensity upgrade [1] in a fieldfree region at the location of the RFA electron detector [2]. By combining our simulated results for the electron flux at the vacuum chamber wall with the corresponding measurements obtained with the RFA we infer that the peak secondary electron yield (SEY) (delta) max is ∼> 1.4, and the average electron density is n e ∼> 10 10 m -3 at transition energy for the specific fill pattern and beam intensities defined below. The sensitivity of our results to several variables remains to be explored in order to reach more definitive results. Effects from the electron cloud on the beam are being investigated separately [3

Measurements of the electron cloud in the APS storage ring

International Nuclear Information System (INIS)

Harkey, K. C.

1999-01-01

Synchrotron radiation interacting with the vacuum chamber walls in a storage ring produce photoelectrons that can be accelerated by the beam, acquiring sufficient energy to produce secondary electrons in collisions with the walls. If the secondary-electron yield (SEY) coefficient of the wall material is greater than one, as is the case with the aluminum chambers in the Advanced Photon Source (APS) storage ring, a runaway condition can develop. As the electron cloud builds up along a train of stored positron or electron bunches, the possibility exists that a transverse perturbation of the head bunch will be communicated to trailing bunches due to interaction with the cloud. In order to characterize the electron cloud, a special vacuum chamber was built and inserted into the ring. The chamber contains 10 rudimentary electron-energy analyzers, as well as three targets coated with different materials. Measurements show that the intensity and electron energy distribution are highly dependent on the temporal spacing between adjacent bunches and the amount of current contained in each bunch. Furthermore, measurements using the different targets are consistent with what would be expected based on the SEY of the coatings. Data for both positron and electron beams are presented

Fast Transverse Beam Instability Caused by Electron Cloud Trapped in Combined Function Magnets

Energy Technology Data Exchange (ETDEWEB)

Antipov, Sergey [Univ. of Chicago, IL (United States)

2017-03-01

Electron cloud instabilities affect the performance of many circular high-intensity particle accelerators. They usually have a fast growth rate and might lead to an increase of the transverse emittance and beam loss. A peculiar example of such an instability is observed in the Fermilab Recycler proton storage ring. Although this instability might pose a challenge for future intensity upgrades, its nature had not been completely understood. The phenomena has been studied experimentally by comparing the dynamics of stable and unstable beam, numerically by simulating the build-up of the electron cloud and its interaction with the beam, and analytically by constructing a model of an electron cloud driven instability with the electrons trapped in combined function dipoles. Stabilization of the beam by a clearing bunch reveals that the instability is caused by the electron cloud, trapped in beam optics magnets. Measurements of microwave propagation confirm the presence of the cloud in the combined function dipoles. Numerical simulations show that up to 10$^{-2}$ of the particles can be trapped by their magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a combined function dipole this multi-turn accumulation allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The estimated fast instability growth rate of about 30 revolutions and low mode frequency of 0.4 MHz are consistent with experimental observations and agree with the simulations. The created instability model allows investigating the beam stability for the future intensity upgrades.

New Electron Cloud Detectors for the PS Main Magnets

CERN Document Server

Yin Vallgren, Ch; Gilardoni, S; Taborelli, M; Neupert, H; Ferreira Somoza, J

2014-01-01

Electron cloud (EC) has already been observed during normal operation of the PS, therefore it is necessary to study its in fluence on any beam instability for the future LHC Injector Upgrade (LIU). Two new electron cloud detectors have been discussed, developed and installed during the Long Shutdown (LS1) in one of the PS main magnets. The first measurement method is based on current measurement by using a shielded button-type pick-up. Due to the geometry and space limitation in the PS magnet, the button-type pick-up made of a 96%Al2O3 block coated with a thin layer of solvent-based Ag painting, placed 30 degrees to the bottom part of the vacuum chamber was installed in the horizontal direction where the only opening of the magnet coil is. The other newly developed measurement method is based on detection of photons emitted by the electrons from the electron cloud impinging on the vacuum chamber walls. The emitted photons are reected to a quartz window. A MCP-PMT (Micro-Channel Plate Photomultiplier Tube) wit...

Observation of magnetic resonances in electron clouds in a positron storage ring

International Nuclear Information System (INIS)

Pivi, M.T.F.; Ng, J.S.T.; Cooper, F.; Kharakh, D.; King, F.; Kirby, R.E.; Kuekan, B.; Spencer, C.M.; Raubenheimer, T.O.; Wang, L.F.

2010-01-01

The first experimental observation of magnetic resonances in electron clouds is reported. The resonance was observed as a modulation in cloud intensity for uncoated as well as TiN-coated aluminum surfaces in the positron storage ring of the PEP-II collider at SLAC. Electron clouds frequently arise in accelerators of positively charged particles, and severely impact the machines' performance. The TiN coating was found to be an effective remedy, reducing the cloud intensity by three orders of magnitude.

Comparison of electron cloud mitigating coatings using retarding field analyzers

Energy Technology Data Exchange (ETDEWEB)

Calvey, J.R., E-mail: jrc97@cornell.edu; Hartung, W.; Li, Y.; Livezey, J.A.; Makita, J.; Palmer, M.A.; Rubin, D.

2014-10-01

In 2008, the Cornell Electron Storage Ring (CESR) was reconfigured to serve as a test accelerator (CESRTA) for next generation lepton colliders, in particular for the ILC damping ring. A significant part of this program has been the installation of diagnostic devices to measure and quantify the electron cloud effect, a potential limiting factor in these machines. One such device is the Retarding Field Analyzer (RFA), which provides information on the local electron cloud density and energy distribution. Several different styles of RFAs have been designed, tested, and deployed throughout the CESR ring. They have been used to study the growth of the cloud in different beam conditions, and to evaluate the efficacy of different mitigation techniques. This paper will provide an overview of RFA results obtained in a magnetic field free environment.

Electron cloud density measurements in accelerator beam-pipe using resonant microwave excitation

Energy Technology Data Exchange (ETDEWEB)

Sikora, John P., E-mail: jps13@cornell.edu [CLASSE, Cornell University, Ithaca, NY 14853 (United States); Carlson, Benjamin T. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Duggins, Danielle O. [Gordon College, Wenham, MA 01984 (United States); Hammond, Kenneth C. [Columbia University, New York, NY 10027 (United States); De Santis, Stefano [LBNL, Berkeley, CA 94720 (United States); Tencate, Alister J. [Idaho State University, Pocatello, ID 83209 (United States)

2014-08-01

An accelerator beam can generate low energy electrons in the beam-pipe, generally called electron cloud, that can produce instabilities in a positively charged beam. One method of measuring the electron cloud density is by coupling microwaves into and out of the beam-pipe and observing the response of the microwaves to the presence of the electron cloud. In the original technique, microwaves are transmitted through a section of beam-pipe and a change in EC density produces a change in the phase of the transmitted signal. This paper describes a variation on this technique in which the beam-pipe is resonantly excited with microwaves and the electron cloud density calculated from the change that it produces in the resonant frequency of the beam-pipe. The resonant technique has the advantage that measurements can be localized to sections of beam-pipe that are a meter or less in length with a greatly improved signal to noise ratio.

Electron-Cloud Build-Up: Theory and Data

International Nuclear Information System (INIS)

Furman, M.A.

2010-01-01

We present a broad-brush survey of the phenomenology, history and importance of the electron-cloud effect (ECE). We briefly discuss the simulation techniques used to quantify the electron-cloud (EC) dynamics. Finally, we present in more detail an effective theory to describe the EC density build-up in terms of a few effective parameters. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC.

Electron cloud studies for SIS-18 and for the FAIR synchrotrons

Energy Technology Data Exchange (ETDEWEB)

Petrov, Fedor; Weiland, Thomas [Technische Universitaet Darmstadt, Institut fuer Theorie Elektromagnetischer Felder (TEMF), Darmstadt (Germany); Boine-Frankenheim, Oliver [Gesellschaft fuer Schwerionenforschung (GSI) GmbH, Darmstadt (Germany)

2010-07-01

Electron clouds generated by residual gas ionization pose a potential threat to the stability of the circulating heavy ion beams in the existing SIS-18 synchrotron and in the projected SIS-100. The electrons can potentially accumulate in the space charge potential of the long bunches. As an extreme case we study the accumulation of electrons in a coasting beam under conditions relevant in the SIS-18. Previous studies of electron clouds in coasting beams used particle-in-cell (PIC) codes to describe the generation of the cloud and the interaction with the ion beam. PIC beams exhibit much larger fluctuation amplitudes than real beams. The fluctuations heat the electrons. Therefore the obtained neutralization degree is strongly reduced, relative to a real beam. In our simulation model we add a Langevin term to the electron equation of motion in order to account for the heating process. The effect of natural beam fluctuations on the neutralization degree is studied. The modification of the beam response function as well as the stability limits in the presence of the electrons is discussed.

Transverse blowup along bunch train caused by electron cloud in BEPC

International Nuclear Information System (INIS)

Liu Yudong; Guo Zhiyuan; Qin Qing; Wang Jiuqing; Zhao Zheng

2006-01-01

Electron cloud instability (ECI) may take place in a storage ring when the machine is operated with a multi-bunch positively charged beam. Transverse blowup due to electron cloud has been observed in some machines and is considered to be a major limit factor in the development of high current and high luminosity electron positron colliders. With a streak camera, the transverse blowup along the bunch train was first observed in an experiment at the Beijing Electron-Positron Collider (BEPC) and the simulation results were used to compared with the observation. (authors)

Electron Cloud Simulations of a Proton Storage Ring Using Cold Proton Bunches

International Nuclear Information System (INIS)

Sato, Y.; Holmes, Jeffrey A.; Lee, S.Y.; Macek, R.

2008-01-01

Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory. Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.

Progress in studies of Electron-Cloud-Induced Optics Distortions at CESRTA

International Nuclear Information System (INIS)

Crittenden, J.A.; Calvey, J.R.; Dugan, G.F.; Kreinick, D.L.; Leong, Z.; Livezey, J.A.; Palmer, M.A.; Rubin, D.L.; Sagan, D.C.; Holtzapple, R.L.; Furman, M.A.; Penn, G.; Venturini, M.; Pivi, M.; Wang, L.; Harkay, K.

2010-01-01

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation program packages has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photoelectrons on the vacuum chamberwall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

Application of low energy electron beam to precoated steel plates

International Nuclear Information System (INIS)

Koshiishi, Kenji

1989-01-01

Recently in the fields of home electric appliances, machinery and equipment and interior building materials, the needs for the precoated steel plates having the design and function of high class increase rapidly. In order to cope with such needs, the authors have advanced the examination on the application of electron beam hardening technology to precoated steel plates, and developed the precoated steel plates of high grade and high design 'Super Tecstar EB Series' by utilizing low energy electron beam. The features of this process are (1) hardening can be done at room temperature in a short time-thermally weak films can be adhered, (2) high energy irradiation-the hardening of thick enamel coating and the adhesion of colored films are feasible, (3) the use of monomers of low molecular weight-by high crosslinking, the performance of high sharpness, high hardness, anti-contamination property and so on can be given. The application to precoated steel plate production process is the coating and curing of electron beam hardening type paints, the coating of films with electron beam hardening type adhesives, and the reforming of surface polymer layers by impregnating monomers and causing graft polymerization with electron beam irradiation. The outline of the Super Tecstar EB Series is described. (K.I.)

Experiments on the injection, confinement, and ejection of electron clouds in a magnetic mirror

International Nuclear Information System (INIS)

Eckhouse, S.; Fisher, A.; Rostoker, N.

1978-01-01

A cloud of (5 to 10 keV) electrons is injected into a magnetic mirror field. The magnetic field rises in 40--120 μsec to a maximum of 10 kG. Two methods of injection were tried: In the first, the injector is located at the mirror midplane and electrons are injected perpendicular to the magnetic field lines. In the second scheme, the injector is located near the mirror maximum. Up to about 10 11 electrons were trapped in both schemes with a mean kinetic energy of 0.3 MeV. Measured confinement time is limited only by the magnetic field decay time. The compressed electron cloud executes electrostatic oscillations. The frequency of the oscillation is proportional to the number of electrons trapped, and it is independent of the value of the magnetic field and the initial electron energy. The electron cloud was ejected along the mirror axis and properties of the ejected electron cloud were measured by x-ray pulses from bremstrahlung of electrons on the vacuum system wall and by collecting electrons on a Faraday cup

CLEARING OF ELECTRON CLOUD IN SNS

International Nuclear Information System (INIS)

WANG, L.; LEE, Y.Y.; RAPRIA, D.

2004-01-01

In this paper we describe a mechanism using the clearing electrodes to remove the electron cloud in the Spallation Neutron Source (SNS) accumulator ring, where strong multipacting could happen at median clearing fields. A similar phenomenon was reported in an experimental study at Los Alamos laboratory's Proton Synchrotron Ring (PSR). We also investigated the effectiveness of the solenoid's clearing mechanism in the SNS, which differs from the short bunch case, such as in B-factories. The titanium nitride (TiN) coating of the chamber walls was applied to reduce the secondary electron yield (SEY)

Progress in Studies of Electron-Cloud-Induced Optics Distortions at CesrTA

International Nuclear Information System (INIS)

Crittenden, James; Penn, Gregory; Venturini, Marco; Harkay, Katherine; Holtzapple, Robert; Pivi, Mauro; Wang, Lanfa

2012-01-01

The Cornell Electron Storage Ring Test Accelerator (CesrTA) program has included extensive measurements of coherent betatron tune shifts for a variety of electron and positron beam energies, bunch population levels, and bunch train configurations. The tune shifts have been shown to result primarily from the interaction of the beam with the space-charge field of the beam-induced low-energy electron cloud in the vacuum chamber. Comparison to several advanced electron cloud simulation codes has allowed determination of the sensitivity of these measurements to physical parameters characterizing the synchrotron radiation flux, the production of photo-electrons on the vacuum chamber wall, the beam emittance, lattice optics, and the secondary-electron yield model. We report on progress in understanding the cloud buildup and decay mechanisms in magnetic fields and in field-free regions, addressing quantitatively the precise determination of the physical parameters of the modeling. Validation of these models will serve as essential input in the design of damping rings for future high-energy linear colliders.

Measurements of the Electron Cloud Density in the PEP-II Low Energy Ring

Energy Technology Data Exchange (ETDEWEB)

Byrd, John; De Santis, Stefano; Sonnad, Kiran; Caspers, Fritz; Kroyer, Tom; Krasnykh, Anatoly; Pivi, Mauro

2008-06-01

Clouds of low energy electronsin the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation of these machines at high currents. Because of the size of these accelerators, it is difficult to probe the low energyelectron clouds over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave that is independently excited and transmitted over a section of the accelerator. We infer the absolute phase shift with relatively high accuracy from the phase modulation of the transmission due to the modulation of the electron cloud density from a gap in the positively charged beam. We have used this technique for the first time to measure the average electron cloud density over a 50 m straight section in the positron ring of the PEP-II collider at the Stanford Linear Accelerator Center. We have also measured the variation of the density by using low field solenoid magnets to control the electrons.

Modeling Incoherent Electron Cloud Effects

International Nuclear Information System (INIS)

Vay, Jean-Luc; Benedetto, E.; Fischer, W.; Franchetti, G.; Ohmi, K.; Schulte, D.; Sonnad, K.; Tomas, R.; Vay, J.-L.; Zimmermann, F.; Rumolo, G.; Pivi, M.; Raubenheimer, T.

2007-01-01

Incoherent electron effects could seriously limit the beam lifetime in proton or ion storage rings, such as LHC, SPS, or RHIC, or blow up the vertical emittance of positron beams, e.g., at the B factories or in linear-collider damping rings. Different approaches to modeling these effects each have their own merits and drawbacks. We describe several simulation codes which simplify the descriptions of the beam-electron interaction and of the accelerator structure in various different ways, and present results for a toy model of the SPS. In addition, we present evidence that for positron beams the interplay of incoherent electron-cloud effects and synchrotron radiation can lead to a significant increase in vertical equilibrium emittance. The magnitude of a few incoherent e+e- scattering processes is also estimated. Options for future code development are reviewed

Experimental Investigation of Electron Cloud Containment in a Nonuniform Magnetic Field

Science.gov (United States)

Eninger, J. E.

1974-01-01

Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 Torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V sub a/phi sub a where V sub a is the anode voltage and phi suba is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this conditions are integrated with respect to total ionizing power and are found consistent with measured discharge currents.

Experimental investigation of electron cloud containment in a nonuniform magnetic field

International Nuclear Information System (INIS)

Eninger, J.E.

1974-05-01

Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V/sub a/phi/sub a/ where V/sub a/ is the anode voltage and phi/sub a/ is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this condition are integrated with respect to total ionizing power and are found consistent with measured discharge currents. (U.S.)

A simulation study of electron-cloud instability and beam-induced multipacting in the LHC

International Nuclear Information System (INIS)

Zimmermann, F.

1997-02-01

In the LHC beam pipe, photoemission and secondary emission give rise to a quasi-stationary electron cloud, which is established after a few bunch passages. The response of this electron cloud to a transversely displaced bunch resembles a short-range wakefield and can cause a fast instability. In addition, beam-induced multipacting of the electrons may lead to an enhanced gas desorption and an associated pressure increase. In this paper the authors report preliminary simulation results of the electron-cloud build-up both in a dipole magnet and in a straight section of the LHC at top energy. The effective wakefield created by the electron cloud translates into an instability rise time of about 25 ms horizontally and 130 ms vertically. This rise time is not much larger than that of the resistive-wall instability at injection energy

Electron Cloud Mitigation in the Spallation Neutron Source Ring

International Nuclear Information System (INIS)

Wei, J.; Blaskiewicz, Michael; Brodowski, J.; Cameron, P.; Davino, Daniele; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Ludewig, H.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Catalan-Lasheras, N.; Macek, R.J.; Furman, Miguel A.; Aleksandrov, A.; Cousineau, S.; Danilov, V.; Henderson, S.

2008-01-01

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H - injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron-cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation

Electron-cloud mitigation in the spallation neutron source ring

International Nuclear Information System (INIS)

Wei, J.; Blaskiewicz, M.; Brodowski, J.; Cameron, P.; Davino, D.; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Danilov, V.; Henderson, S.; Furman, M.; Pivi, M.; Macek, R.

2003-01-01

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H- injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation

Electron cloud development in the Proton Storage Ring and in the Spallation Neutron Source

International Nuclear Information System (INIS)

Pivi, M.T.F.; Furman, M.A.

2002-01-01

We have applied our simulation code ''POSINST'' to evaluate the contribution to the growth rate of the electron-cloud instability in proton storage rings. Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A key ingredient in our model is a detailed description of the secondary emitted-electron energy spectrum. A refined model for the secondary emission process including the so-called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code

HINS R and D Collaboration on Electron Cloud Effects: Midyear Report

International Nuclear Information System (INIS)

Furman, M.A.; Sonnad, K.; Vay, J.-L.

2006-01-01

We present a report on ongoing activities on electron-cloud R and D for the MI upgrade. These results update and extend those presented in Refs. 1, 2. In this report we have significantly expanded the parameter range explored in bunch intensity Nb, RMS bunch length σ z and peak secondary emission yield (SEY) (delta) max , but we have constrained our simulations to a field-free region. We describe the threshold behaviors in all of the above three parameters. For (delta) max (ge) 1.5 we find that, even for N b = 1 x 10 11 , the electron cloud density, when averaged over the entire chamber, exceeds the beam neutralization level, but remains significantly below the local neutralization level (ie., when the electron density is computed in the neighborhood of the beam). This 'excess' of electrons is accounted for by narrow regions of high concentration of electrons very close to the chamber surface, especially at the top and bottom of the chamber, akin to virtual cathodes. These virtual cathodes are kept in equilibrium, on average, by a competition between space-charge forces (including their images) and secondary emission, a mechanism that shares some features with the space-charge saturation of the current in a diode at high fields. For N b = 3 x 10 11 the electron cloud build-up growth rate and saturation density have a strong dependence on σ z as σ z decreases below ∼ 0.4 m, when the average electron-wall impact energy roughly reaches the energy E max where (delta) peaks. We also present improved results on emittance growth simulations of the beam obtained with the code WARP/POSINST in quasi-static mode, in which the beam-(electron cloud) interaction is lumped into N s 'stations' around the ring, where N s = 1, 2,..., 9. The emittance shows a rapid growth of ∼ 20% during the first ∼ 100 turns, followed by a much slower growth rate of ∼ 0.03%/turn. Concerning the electron cloud detection technique using microwave transmission, we present an improved

THE INFLUENCE OF POSTHEAT TREATMENT ON FERRITE REDISTRIBUTION IN DUPLEX STEELS ELECTRON BEAM WELDS

OpenAIRE

Zita Iždinská; František Kolenič

2009-01-01

The duplex stainless steel is two-phase steel with the structure composed of austenite and ferrite with optimum austenite/ferrite proportion 50%. At present, classical arc processes for welding duplex steels are generally regarded as acceptable. On the other hand electron and laser beam welding is up to now considered less suitable for welding duplex steels. The submitted work presents the results of testing various thermal conditions at welding duplex stainless steel with electron beam. It w...

CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

International Nuclear Information System (INIS)

Rubin, David L.; Palmer, Mark A.

2011-01-01

In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

Energy Technology Data Exchange (ETDEWEB)

Rubin, David L.; Palmer, Mark A.

2011-08-02

In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

Electron Beam Welding of Duplex Steels with using Heat Treatment

Science.gov (United States)

Schwarz, Ladislav; Vrtochová, Tatiana; Ulrich, Koloman

2010-01-01

This contribution presents characteristics, metallurgy and weldability of duplex steels with using concentrated energy source. The first part of the article describes metallurgy of duplex steels and the influence of nitrogen on their solidification. The second part focuses on weldability of duplex steels with using electron beam aimed on acceptable structure and corrosion resistance performed by multiple runs of defocused beam over the penetration weld.

Status of experimental studies of electron cloud effects at the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

2004-01-01

Various electron cloud effects (ECE) including the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR) have been studied extensively for the past five years with the goal of understanding the phenomena, mitigating the instability and ultimately increasing beam intensity. The specialized diagnostics used in the studies are two types of electron detectors, the retarding field analyzer and the electron sweepmg detector - which have been employed to measure characteristics of the electron cloud as functions of time, location in the ring and various influential beam parameters - plus a short stripline beam position monitor used to measure high frequency motion of the beam centroid. Highlights of this research program are summarized along with more detail on recent results obtained since the ECLOUD'02 workshop. Recent work mcludes a number of parametric studies of the various factors that affect the electron cloud signals, studies of the sources of initial or 'seed' electrons, additional observations of electron cloud dissipation after the beam pulse is extracted, studies of the 'first pulse instability' issue, more data on electron suppression as a cure for the instability, and observations of the effect of a one-turn weak kick on intense beams in the presence of a significant electron cloud.

Electron cloud studies for the LHC and future proton colliders

CERN Document Server

Domínguez Sánchez de la Blanca, César Octavio; Zimmermann, Frank

2014-01-01

The Large Hadron Collider (LHC) is the world’s largest and most powerful particle collider. Its main objectives are to explore the validity of the standard model of particle physics and to look for new physics beyond it, at unprecedented collision energies and rates. A good luminosity performance is imperative to attain these goals. In the last stage of the LHC commissioning (2011-2012), the limiting factor to achieving the design bunch spacing of 25 ns has been the electron cloud effects. The electron cloud is also expected to be the most important luminosity limitation after the first Long Shut-Down of the LHC (LS1), when the machine should be operated at higher energy and with 25-ns spacing, as well as for the planned luminosity upgrade (HL-LHC) and future high energy proton colliders (HE-LHC and VHE-LHC). This thesis contributes to the understanding of the electron cloud observations during the first run of the LHC (2010-2012), presents the first beam dynamics analysis for the next generation of high en...

Combined phenomena of beam-beam and beam-electron cloud interactionsin circular e^{+}e^{-} colliders

Directory of Open Access Journals (Sweden)

Kazuhito Ohmi

2002-10-01

Full Text Available An electron cloud causes various effects in high intensity positron storage rings. The positron beam and the electron cloud can be considered a typical two-stream system with a certain plasma frequency. Beam-beam interaction is another important effect for high luminosity circular colliders. Colliding two beams can be considered as a two-stream system with another plasma frequency. We study the combined phenomena of the beam-electron cloud and beam-beam interactions from a viewpoint of two complex two-stream effects with two plasma frequencies.

Measurements of electron cloud growth and mitigation in dipole, quadrupole, and wiggler magnets

Energy Technology Data Exchange (ETDEWEB)

Calvey, J.R., E-mail: jrc97@cornell.edu; Hartung, W.; Li, Y.; Livezey, J.A.; Makita, J.; Palmer, M.A.; Rubin, D.

2015-01-11

Retarding field analyzers (RFAs), which provide a localized measurement of the electron cloud, have been installed throughout the Cornell Electron Storage Ring (CESR), in different magnetic field environments. This paper describes the RFA designs developed for dipole, quadrupole, and wiggler field regions, and provides an overview of measurements made in each environment. The effectiveness of electron cloud mitigations, including coatings, grooves, and clearing electrodes, are assessed with the RFA measurements.

Electron beam cladding of titanium on stainless steel plate

International Nuclear Information System (INIS)

Tomie, Michio; Abe, Nobuyuki; Yamada, Masanori; Noguchi, Shuichi.

1990-01-01

Fundamental characteristics of electron beam cladding was investigated. Titanium foil of 0.2mm thickness was cladded on stainless steel plate of 3mm thickness by scanning electron beam. Surface roughness and cladded layer were analyzed by surface roughness tester, microscope, scanning electron microscope and electron probe micro analyzer. Electron beam conditions were discussed for these fundamental characteristics. It is found that the energy density of the electron beam is one of the most important factor for cladding. (author)

Manufacturing prepainted steel sheet by electron beam curing

International Nuclear Information System (INIS)

Oka, Joji

1987-01-01

Several advantages are offered by electron beam curing. A formidably hard and stain resistant paint film which is difficult to obtain by heat curing paint is developed. As a result, a unique new prepainted steel is produced. Four technologies are involved: development high-quality paint, selection of optimum electron beam processor, technology to control electron beam processing atmosphere and secondary X-ray shield technology. These technologies are described in detail. (A.J.)

Simulation and Analysis of Microwave Transmission through an Electron Cloud, a Comparison of Results

International Nuclear Information System (INIS)

Sonnad, Kiran; Sonnad, Kiran; Furman, Miguel; Veitzer, Seth; Stoltz, Peter; Cary, John

2007-01-01

Simulation studies for transmission of microwaves through electron clouds show good agreement with analytic results. The electron cloud produces a shift in phase of the microwave. Experimental observation of this phenomena would lead to a useful diagnostic tool for accessing the local density of electron clouds in an accelerator. These experiments are being carried out at the CERN SPS and the PEP-II LER at SLAC and is proposed to be done at the Fermilab main injector. In this study, a brief analysis of the phase shift is provided and the results are compared with that obtained from simulations

Electron Cloud Effects in Accelerators

International Nuclear Information System (INIS)

Furman, M A

2013-01-01

We present a brief summary of various aspects of the electron-cloud effect (ECE) in accelerators. For further details, the reader is encouraged to refer to the proceedings of many prior workshops, either dedicated to EC or with significant EC contents, including the entire 'ECLOUD' series. In addition, the proceedings of the various flavors of Particle Accelerator Conferences contain a large number of EC-related publications. The ICFA Beam Dynamics Newsletter series contains one dedicated issue, and several occasional articles, on EC. An extensive reference database is the LHC website on EC. (author)

Application of Coherent Tune Shift Measurements to the Characterization of Electron Cloud Growth

International Nuclear Information System (INIS)

Kreinick, D.L.; Crittenden, J.A.; Dugan, G.; Holtzapple, R.L.; Randazzo, M.; Furman, M.A.; Venturini, M.; Palmer, M.A.; Ramirez, G.

2011-01-01

Measurements of coherent tune shifts at the Cornell Electron Storage Ring Test Accelerator (CesrTA) have been made for electron and positron beams under a wide variety of beam energies, bunch charge, and bunch train configurations. Comparing the observed tunes with the predictions of several electron cloud simulation programs allows the evaluation of important parameters in these models. These simulations will be used to predict the behavior of the electron cloud in damping rings for future linear colliders. We outline recent improvements to the analysis techniques that should improve the fidelity of the modeling.

Simulation of the interaction of positively charged beams and electron clouds

International Nuclear Information System (INIS)

Markovik, Aleksandar

2013-01-01

The incoherent (head-tail) effect on the bunch due to the interaction with electron clouds (e-clouds) leads to a blow up of the transverse beam size in storage rings operating with positively charged beams. Even more the e-cloud effects are considered to be the main limiting factor for high current, high-brightness or high-luminosity operation of future machines. Therefore the simulation of e-cloud phenomena is a highly active field of research. The main focus in this work was set to a development of a tool for simulation of the interaction of relativistic bunches with non-relativistic parasitic charged particles. The result is the Particle-In-Cell Program MOEVE PIC Tracking which can track a 3D bunch under the influence of its own and external electromagnetic fields but first and foremost it simulates the interaction of relativistic positively charged bunches and initially static electrons. In MOEVE PIC Tracking the conducting beam pipe can be modeled with an arbitrary elliptical cross-section to achieve more accurate space charge field computations for both the bunch and the e-cloud. The simulation of the interaction between positron bunches and electron clouds in this work gave a detailed insight of the behavior of both particle species during and after the interaction. Further and ultimate goal of this work was a fast estimation of the beam stability under the influence of e-clouds in the storage ring. The standard approach to simulate the stability of a single bunch is to track the bunch particles through the linear optics of the machine by multiplying the 6D vector of each particle with the transformation matrices describing the lattice. Thereby the action of the e-cloud on the bunch is approximated by a pre-computed wake kick which is applied on one or more points in the lattice. Following the idea of K.Ohmi the wake kick was pre-computed as a two variable function of the bunch part exiting the e-cloud and the subsequent parts of a bunch which receive a

Electron beam freeforming of stainless steel using solid wire feed

International Nuclear Information System (INIS)

Wanjara, P.; Brochu, M.; Jahazi, M.

2007-01-01

The use of electron beam technology for freeforming build-ups on 321 stainless steel substrates was investigated in this work by using 347 stainless steel as a filler metal. The electron beam freeforming studies indicated that line build-ups could be deposited on the substrate material for optimized processing conditions and a slight linear thickening of the re-build occurred as a function of the deposited layer. The evolution in the formation of the Ti (C, N) (Nb, Ti) carbonitrides and Nb (C, N) precipitates was demonstrated to counteract the formation of detrimental Cr-carbides usually observed during welding stainless steels. The mechanical properties of the re-build were similar to the properties of the base metal, showing that homogeneous properties can be expected in the repaired components

THE INFLUENCE OF POSTHEAT TREATMENT ON FERRITE REDISTRIBUTION IN DUPLEX STEELS ELECTRON BEAM WELDS

Directory of Open Access Journals (Sweden)

Zita Iždinská

2009-04-01

Full Text Available The duplex stainless steel is two-phase steel with the structure composed of austenite and ferrite with optimum austenite/ferrite proportion 50%. At present, classical arc processes for welding duplex steels are generally regarded as acceptable. On the other hand electron and laser beam welding is up to now considered less suitable for welding duplex steels. The submitted work presents the results of testing various thermal conditions at welding duplex stainless steel with electron beam. It was shown, that application of suitable postheat made possible to reduce the ferrite content in weld metal.

Electron Cloud Buildup Characterization Using Shielded Pickup Measurements and Custom Modeling Code at CESRTA

CERN Document Server

Crittenden, James A

2013-01-01

The Cornell Electron Storage Ring Test Accelerator experimental program includes investigations into electron cloud buildup, applying various mitigation techniques in custom vacuum chambers. Among these are two 1.1-m-long sections located symmetrically in the east and west arc regions. These chambers are equipped with pickup detectors shielded against the direct beam-induced signal. They detect cloud electrons migrating through an 18-mm-diameter pattern of small holes in the top of the chamber. A digitizing oscilloscope is used to record the signals, providing time-resolved information on cloud development. Carbon-coated, TiN-coated and uncoated aluminum chambers have been tested. Electron and positron beams of 2.1, 4.0 and 5.3 GeV with a variety of bunch populations and spacings in steps of 4 and 14 ns have been used. Here we report on results from the ECLOUD modeling code which highlight the sensitivity of these measurements to the physical phenomena determining cloud buildup such as the photoelectron produ...

Benchmarking headtail with electron cloud instabilities observed in the LHC

CERN Document Server

Bartosik, H.; Iadarola, G.; Papaphilippou, Y.; Rumolo, G.

2013-01-01

After a successful scrubbing run in the beginning of 2011, the LHC can be presently operated with high intensity proton beams with 50 ns bunch spacing. However, strong electron cloud effects were observed during machine studies with the nominal beam with 25 ns bunch spacing. In particular, fast transverse instabilities were observed when attempting to inject trains of 48 bunches into the LHC for the first time. An analysis of the turn-by-turn bunch-bybunch data from the transverse damper pick-ups during these injection studies is presented, showing a clear signature of the electron cloud effect. These experimental observations are reproduced using numerical simulations: the electron distribution before each bunch passage is generated with PyECLOUD and used as input for a set of HEADTAIL simulations. This paper describes the simulation method as well as the sensitivity of the results to the initial conditions for the electron build-up. The potential of this type of simulations and their clear limitations on th...

Joint CARE-ELAN, CARE-HHH-APD, and EUROTEV-WP3 Workshop on Electron Cloud Clearing

CERN Document Server

Scandale, Walter; Schulte, D; Zimmermann, F; Electron Cloud Effects and Technological Consequences; ECL2

2007-01-01

This report contains the Proceedings of the joint CARE-HHH-APD, CARE-ELAN, and EUROTEV-WP3 Mini-Workshop on 'Electron Cloud Clearing - Electron Cloud and Technical Consequences', "ECL2", held at CERN in Geneva, Switzerland, 1-2 March 2007). The ECL2 workshop explored novel technological remedies against electron-cloud formation in an accelerator beam pipe. A primary motivation for the workshop was the expected harmful electron-cloud effects in the upgraded LHC injectors and in future linear colliders, as well as recent beam observations in operating facilities like ANKA, CESR, KEKB, RHIC, and SPS. The solutions discussed at ECL2 included enamel-based clearing electrodes, slotted vacuum chambers, NEG coating, and grooves. Several of the proposed cures were assessed in terms of their clearing efficiency and the associated beam impedance. The workshop also reviewed new simulation tools like the 3D electron-ion build-up 'Faktor', modeling assumptions, analytical calculations, beam experiments, and laboratory meas...

Summary: Electron-cloud effects and fast-ion instability

International Nuclear Information System (INIS)

Furman, Miguel A.

2000-01-01

This is my summary of the talks on the electron-cloud effect and the fast-ion instability that were presented at the 8th ICFA Beam Dynamics Mini-Work shop on Two-Stream Instabilities in Particle Accelerators and Storage Rings,Santa Fe, NM, February 16--18, 2000

Electron-cloud updated simulation results for the PSR, and recent results for the SNS

International Nuclear Information System (INIS)

Pivi, M.; Furman, M.A.

2002-01-01

Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code

Electron-cloud instabilities and beam-induced multipacting in the LHC and in the VLHC

International Nuclear Information System (INIS)

Zimmermann, F.

1997-10-01

In the beam pipe of the Large Hadron Collider (LHC), photoemission and secondary emission give rise to a quasi-stationary electron cloud, which is established after a few buncn passages. The response of this electron cloud to a transversely displaced bunch resembles a short-range wakefield and can cause a fast instability. In additoin, beam-induced multipacting of the electrons may lead to an enhanced gas desorption and an associated pressure increase. In this paper the authors report preliminary simulation results of the electron-cloud build-up both in a dipole magnet and in a straight section of the LHC at top energy. The effective wakefield created by the electron cloud translates into an instability rise time of about 40 ms horizontally and 500 ms vertically. This rise time is not much larger than that of the resistive-wall instability at injection energy. Similar simulation studies show that the instability rise time for the proposed Very Large Hadron Collider (VLHC) is about 3--4 s in both trasnverse planes. The smaller growth rate in the VLHC, as compared with the LHC, is primarily due to the much lower bunch population

Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

International Nuclear Information System (INIS)

De Santis, S.; Byrd, J.M.; Billing, M.; Palmer, M.; Sikora, J.; Carlson, B.

2010-01-01

A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated (S. De Santis, J.M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M.T.F. Pivi, and K.G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008).). We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

Progress on electron cloud effects calculations for the FNAL main injector

International Nuclear Information System (INIS)

Furman, Miguel A; Sonnad, Kiran G.; Furman, Miguel A.; Vay, Jean-Luc

2008-01-01

We have studied the response of the beam to an electron cloud for the Fermilab Main Injector using the Quasistatic Model [1] implemented into the particle-in-cell code Warp [2]. Specifically, we have addressed the effects due to varying the beam intensity, electron cloud density and chromaticity. In addition, we have estimated the contribution to emittance evolution due to beam space-charge effects. We have carried out a comparison between how the beam responds at injection energy and at top energy. We also present some results on the validation of the computational model, and report on progress towards improving the computational model

Electron-cloud simulation results for the PSR and SNS

International Nuclear Information System (INIS)

Pivi, M.; Furman, M.A.

2002-01-01

We present recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos. In particular, a complete refined model for the secondary emission process including the so called true secondary, rediffused and backscattered electrons has been included in the simulation code

Preliminary Analysis and Simulation Results of Microwave Transmission Through an Electron Cloud

International Nuclear Information System (INIS)

Sonnad, Kiran; Sonnad, Kiran; Furman, Miguel; Veitzer, Seth; Stoltz, Peter; Cary, John

2007-01-01

The electromagnetic particle-in-cell (PIC) code VORPAL is being used to simulate the interaction of microwave radiation through an electron cloud. The results so far show good agreement with theory for simple cases. The study has been motivated by previous experimental work on this problem at the CERN SPS [1], experiments at the PEP-II Low Energy Ring (LER) at SLAC [4], and proposed experiments at the Fermilab Main Injector (MI). With experimental observation of quantities such as amplitude, phase and spectrum of the output microwave radiation and with support from simulations for different cloud densities and applied magnetic fields, this technique can prove to be a useful probe for assessing the presence as well as the density of electron clouds

Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects

CERN Document Server

Rumolo, Giovanni; Zimmermann, Frank; ECLOUD'12

2013-01-01

This report contains the Proceedings of the Joint INFN-Frascati, INFN-Pisa, CERN-LER and EuCARD-AccNet Mini-Workshop on Electron-Cloud Effects, “ECLOUD12”, held at La Biodola, Isola d’Elba, from 5 to 9 June 2012. The ECLOUD12 workshop reviewed many recent electron-cloud (EC) observations at existing storage rings, EC predictions for future accelerators, electron-cloud studies at DAFNE, EC mitigation by clearing electrodes and graphite/carbon coatings, modeling of incoherent EC effects, self-consistent simulations, synergies with other communities like the Valencia Space Consortium and the European Space Agency. ECLOUD12 discussed new EC observations at existing machines including LHC, CesrTA, PETRA-3, J-PARC, and FNAL MI; latest experimental efforts to characterize the EC – including EC diagnostics, experimental techniques, mitigation techniques such as coating and conditioning, advanced chemical and physical analyses of various vacuum-chamber surfaces, beam instabilities and emittance growth –; the...

Simulations of Electron Cloud Effects on the Beam Dynamics for the FNAL Main Injector Upgrade

International Nuclear Information System (INIS)

Sonnad Kiran G.; Furman, Miguel; Vay, Jean-Luc; Venturini, Marco; Celata, Christine M.; Grote, David

2006-01-01

The Fermilab main injector (MI) is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort. This upgrade will involve a significant increasing of the bunch intensity relative to its present value. Such an increase will place the MI in a regime in which electron-cloud effects are expected to become important. We have used the electrostatic particle-in-cell code WARP, recently augmented with new modeling capabilities and simulation techniques, to study the dynamics of beam-electron cloud interaction. This work in progress involves a systematic assessment of beam instabilities due to the presence of electron clouds

The size and spatial distribution of microchannel plate output electron clouds

International Nuclear Information System (INIS)

Lapington, J.S.; Edgar, M.L.

1989-01-01

An experimental technique for measuring the spatial distribution of the output charge cloud from a microchannel plate (MCP), using a planar, charge-division-type anode is discussed. The anode simultaneously measures, for each charge cloud, both the position of the charge centroid and the fractional charge falling to one side of the split in the pattern. The measurements from several thousand events have been combined to calculate the average spatial distribution of the electron cloud and the dominant factors influencing the charge cloud distribution have been found to be the MCP gain and the MCP-anode accelerating field and geometry. Experimental research on the two dominant factors with respect to ranges of distribution is presented. 10 refs

Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

Directory of Open Access Journals (Sweden)

S. De Santis

2010-07-01

Full Text Available A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated [S. De Santis, J. M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M. T. F. Pivi, and K. G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008.PRLTAO0031-900710.1103/PhysRevLett.100.094801]. We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

RFID-based Electronic Identity Security Cloud Platform in Cyberspace

OpenAIRE

Bing Chen; Chengxiang Tan; Bo Jin; Xiang Zou; Yuebo Dai

2012-01-01

With the moving development of networks, especially Internet of Things, electronic identity administration in cyberspace is becoming more and more important. And personal identity management in cyberspace associated with individuals in reality has been one significant and urgent task for the further development of information construction in China. So this paper presents a RFID-based electronic identity security cloud platform in cyberspace to implement an efficient security management of cyb...

Electron-microscope study of cloud and fog nuclei

Energy Technology Data Exchange (ETDEWEB)

Ogiwara, S; Okita, T

1952-01-01

Droplets of clouds on a mountain and of fog in an urban area were captured and the form, nature and size of their nuclei were studied by means of an electron-microscope and by a chamber of constant humidity. These nuclei have similar form and nature to the hygroscopic particles in haze and to the artificially produced combustion particles. No sea-salt nuclei were found in our observations, therefore, sea-spray appears to be an insignificant source of condensation nuclei. It was found that both the cloud and the fog nuclei originated in combustion products which were the mixture of hygroscopic and non-hygroscopic substances, and that the greater part of the nuclei did not contain pure sulfuric acid.

New simulation capabilities of electron clouds in ion beams with large tune depression

International Nuclear Information System (INIS)

Vay, J.L.; Furman, M.A.; Seidl, P.A.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Kireeff-Covo, M.; Molvik, A.W.; Stoltz, P.H.; Veitzer, S.; Verboncoeur, J.P.

2006-01-01

The authors have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D ''slice'' e-cloud code POSINST, as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new ''drift-Lorentz'' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX). They describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC)

Single-Bunch Instability Driven by the Electron Cloud Effect in the Positron Damping Ring of the International Linear Collider

International Nuclear Information System (INIS)

Pivi, Mauro; Raubenheimer, Tor O.; Ghalam, Ali; Harkay, Katherine; Ohmi, Kazuhito; Wanzenberg, Rainer; Wolski, Andrzej; Zimmermann, Frank

2005-01-01

Collective instabilities caused by the formation of an electron cloud (EC) are a potential limitation to the performances of the damping rings for a future linear collider. In this paper, we present recent simulation results for the electron cloud build-up in damping rings of different circumferences and discuss the single-bunch instabilities driven by the electron cloud

First electron-cloud studies at the Large Hadron Collider

CERN Document Server

Dominguez, O; Arduini, G; Metral, E; Rumolo, G; Zimmermann, F; Maury Cuna, H

2013-01-01

During the beam commissioning of the Large Hadron Collider (LHC) with 150, 75, 50, and 25-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities, or emittance growth, were observed. Methods have been developed to infer different key beam-pipe surface parameters by benchmarking simulations and pressure rise as well as heat-load observations. These methods allow us to monitor the scrubbing process, i.e., the reduction of the secondary emission yield as a function of time, in order to decide on the most appropriate strategies for machine operation. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to examine both the coherent and the incoherent effects on the beam. In this paper we present the methodology and first results for the scrubbing monitoring process at the LHC. We also review simulated instability thresholds and tune footprints for beams of different emittance, interacting with an electr...

New simulation capabilities of electron clouds in ion beams with large tune depression

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Seidl, P.A.

2007-01-01

We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D 'slice' e-cloud code POSINST [M. Furman, this workshop, paper TUAX05], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new 'drift-Lorentz' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop, paper THAW02]. We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC). (author)

New simulation capabilities of electron clouds in ion beams with large tune depression

International Nuclear Information System (INIS)

Lawrence Livermore National Laboratory

2006-01-01

We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D ''slice'' e-cloud code POSINST [M. Furman, this workshop, paper TUAX05], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new ''drift-Lorentz'' particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop, paper THAW02]. We describe the capabilities and present recent simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC)

Simulations of the Electron Cloud Build Up and Instabilities for Various ILC Damping Ring Configurations

International Nuclear Information System (INIS)

Pivi, Mauro; Raubenheimer, Tor O.; Wang, Lanfa; Ohmi, Kazuhito; Wanzenberg, Rainer; Wolski, Andrzej

2007-01-01

In the beam pipe of the positron damping ring of the International Linear Collider (ILC), an electron cloud may be first produced by photoelectrons and ionization of residual gases and then increased by the secondary emission process. This paper reports the assessment of electron cloud effects in a number of configuration options for the ILC baseline configuration. Careful estimates were made of the secondary electron yield (sometimes in the literature also referred as secondary emission yield SEY or (delta), with a peak value (delta) max ) threshold for electron cloud build-up, and the related single- and coupled-bunch instabilities, as a function of beam current and surface properties for a variety of optics designs. When the configuration for the ILC damping rings was chosen at the end of 2005, the results from these studies were important considerations. On the basis of the joint theoretical and experimental work, the baseline configuration currently specifies a pair of 6 km damping rings for the positron beam, to mitigate the effects of the electron cloud that could present difficulties in a single 6 km ring. However, since mitigation techniques are now estimated to be sufficiently mature, a reduced single 6-km circumference is presently under consideration so as to reduce costs

Accurate simulation of the electron cloud in the Fermilab Main Injector with VORPAL

Energy Technology Data Exchange (ETDEWEB)

Lebrun, Paul L.G.; Spentzouris, Panagiotis; /Fermilab; Cary, John R.; Stoltz, Peter; Veitzer, Seth A.; /Tech-X, Boulder

2010-05-01

Precision simulations of the electron cloud at the Fermilab Main Injector have been studied using the plasma simulation code VORPAL. Fully 3D and self consistent solutions that includes E.M. field maps generated by the cloud and the proton bunches have been obtained, as well detailed distributions of the electron's 6D phase space. We plan to include such maps in the ongoing simulation of the space charge effects in the Main Injector. Simulations of the response of beam position monitors, retarding field analyzers and microwave transmission experiments are ongoing.

Capabilities and Advantages of Cloud Computing in the Implementation of Electronic Health Record.

Science.gov (United States)

Ahmadi, Maryam; Aslani, Nasim

2018-01-01

With regard to the high cost of the Electronic Health Record (EHR), in recent years the use of new technologies, in particular cloud computing, has increased. The purpose of this study was to review systematically the studies conducted in the field of cloud computing. The present study was a systematic review conducted in 2017. Search was performed in the Scopus, Web of Sciences, IEEE, Pub Med and Google Scholar databases by combination keywords. From the 431 article that selected at the first, after applying the inclusion and exclusion criteria, 27 articles were selected for surveyed. Data gathering was done by a self-made check list and was analyzed by content analysis method. The finding of this study showed that cloud computing is a very widespread technology. It includes domains such as cost, security and privacy, scalability, mutual performance and interoperability, implementation platform and independence of Cloud Computing, ability to search and exploration, reducing errors and improving the quality, structure, flexibility and sharing ability. It will be effective for electronic health record. According to the findings of the present study, higher capabilities of cloud computing are useful in implementing EHR in a variety of contexts. It also provides wide opportunities for managers, analysts and providers of health information systems. Considering the advantages and domains of cloud computing in the establishment of HER, it is recommended to use this technology.

Concerning the maximum energy of ions accelerated at the front of a relativistic electron cloud expanding into vacuum

International Nuclear Information System (INIS)

Bulanov, S.V.; Esirkepov, T.Zh.; Koga, J.; Tajima, T.; Farina, D.

2004-01-01

Results of particle-in-cell simulations are presented that demonstrate characteristic interaction regimes of high-power laser radiation with plasma. It is shown that the maximum energy of fast ions can substantially exceed the electron energy. A theoretical model is proposed of ion acceleration at the front of a relativistic electron cloud expanding into vacuum in the regime of strong charge separation. The model describes the electric field structure and the dynamics of fast ions inside the electron cloud. The maximum energy the ions can gain at the front of the expanding electron cloud is found

Observation of transverse and longitudinal modes in non-neutral electron clouds confined in a magnetic mirror

International Nuclear Information System (INIS)

Eckhouse, S.; Fisher, A.; Rostoker, N.

1979-01-01

Electrostatic modes on non-neutral electron clouds confined in a magnetic mirror field have been investigated. The cloud contains 2 x 10 11 electrons at an average kinetic energy of 0.3 MeV for a magnetic field with a peak intensity of 9 kG at the midplane. It was found that the cloud is moving azimuthally as well as longitudinally. The azimuthal motion has an m=1 spatial nature. The longitudinal modes have a more complicated nature, but their frequency equals that of the azimuthal mode

Simulation of electron cloud effects to heavy ion beams

Energy Technology Data Exchange (ETDEWEB)

Yaman, Fatih; Gjonaj, Erion; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder

2011-07-01

Electron cloud (EC) driven instability can cause beam loss, emittance growth, trajectory change and wake fields. Mentioned crucial effects of EC motivated researchers to understand the EC build up mechanism and the effects of EC to the beam. This motivation also induced the progress of developing new simulation codes. EC simulations can roughly be divided into two classes such as, softwares whose goals are to simulate the build up of the EC during the passage of a bunch train and the codes which model the interaction of a bunch with an EC. The aim of this study is to simulate the effects of electron cloud (EC) on the dynamics of heavy ion beams which are used in heavy ion synchrotron (SIS-18) at GSI. To do this, a 3-D and self-consistent simulation program based on particle in cell (PIC) method is used. In the PIC cycle, accurate solution of the Maxwell equations is obtained by employing discontinuous Galerkin finite element method. As a model, we assumed a perfectly conducting beam pipe which was uniformly (or randomly) loaded with the electrons. Then as parallel with the realistic cases in SIS-18, a single bunch consisting of U{sup +73} ions was extracted which could propagate in this pipe. Due to EC-ion bunch interaction, electrons gained energy and their displacements were observed. Electric and magnetic field components and EC charge density were calculated, numerically.

Elves and associated electron density changes due to cloud-to-ground and in-cloud lightning discharges

Science.gov (United States)

Marshall, R. A.; Inan, U. S.; Glukhov, V. S.

2010-04-01

A 3-D finite difference time domain model is used to simulate the lightning electromagnetic pulse (EMP) and its interaction with the lower ionosphere. Results agree with the frequently observed, doughnut-shaped optical signature of elves but show that the structure exhibits asymmetry due to the presence of Earth's ambient magnetic field. Furthermore, in-cloud (horizontal) lightning channels produce observable optical emissions without the doughnut shape and, in fact, produce a much stronger optical output for the same channel current. Electron density perturbations associated with elves are also calculated, with contributions from attachment and ionization. Results presented as a function of parameters such as magnetic field direction, dipole current orientation, altitude and amplitude, and ambient ionospheric density profile demonstrate the highly nonlinear nature of the EMP-ionosphere interaction. Ionospheric effects of a sequence of in-cloud discharges are calculated, simulating a burst of in-cloud lightning activity and resulting in large density changes in the overlying ionosphere.

An analytic model for the electrostatic contribution of the electron cloud to the vertical tune-shift

International Nuclear Information System (INIS)

Schaechter, Levi

2008-01-01

An analytic quasi-static model is developed for the analysis of the tune-shift associated with the presence of an electron cloud in a damping ring. The essential assumption is that in its direction of motion, a bunch experiences a uniform cloud density but the latter varies from one bunch to another. A second important component of the model is the life-time since it controls the build-up, the equilibrium as well as the decay of the cloud. It is demonstrated analytically that in case of a train of positron bunches, electrons may be trapped in the vertical direction for the entire train duration. Assuming that the ring is dominated by vertical magnetic fields due to either bends or wigglers, we found excellent agreement between the theoretical predictions and the experimental results reported at Cornell Electron/Positron Storage Ring. The ratio between the vertical and horizontal tune-shifts is shown to be indicative of the distribution of the cloud in the beam-chamber

Enhanced quasi-static particle-in-cell simulation of electron cloud instabilities in circular accelerators

Science.gov (United States)

Feng, Bing

Electron cloud instabilities have been observed in many circular accelerators around the world and raised concerns of future accelerators and possible upgrades. In this thesis, the electron cloud instabilities are studied with the quasi-static particle-in-cell (PIC) code QuickPIC. Modeling in three-dimensions the long timescale propagation of beam in electron clouds in circular accelerators requires faster and more efficient simulation codes. Thousands of processors are easily available for parallel computations. However, it is not straightforward to increase the effective speed of the simulation by running the same problem size on an increasingly number of processors because there is a limit to domain size in the decomposition of the two-dimensional part of the code. A pipelining algorithm applied on the fully parallelized particle-in-cell code QuickPIC is implemented to overcome this limit. The pipelining algorithm uses multiple groups of processors and optimizes the job allocation on the processors in parallel computing. With this novel algorithm, it is possible to use on the order of 102 processors, and to expand the scale and the speed of the simulation with QuickPIC by a similar factor. In addition to the efficiency improvement with the pipelining algorithm, the fidelity of QuickPIC is enhanced by adding two physics models, the beam space charge effect and the dispersion effect. Simulation of two specific circular machines is performed with the enhanced QuickPIC. First, the proposed upgrade to the Fermilab Main Injector is studied with an eye upon guiding the design of the upgrade and code validation. Moderate emittance growth is observed for the upgrade of increasing the bunch population by 5 times. But the simulation also shows that increasing the beam energy from 8GeV to 20GeV or above can effectively limit the emittance growth. Then the enhanced QuickPIC is used to simulate the electron cloud effect on electron beam in the Cornell Energy Recovery Linac

Mass attenuation coefficients, effective atomic and electron numbers of stainless steel and carbon steels with different energies

International Nuclear Information System (INIS)

Mohd Fakarudin Abdul Rahman; Mohd Iqbal Saripan; Nor Paiza Mohamad Hasan; Ismail Mustapha

2011-01-01

The total mass attenuation coefficients (μ/ ρ) of stainless steel (SS316L) and carbon steel (A516) that are widely used as petrochemical plant components, such as distillation column, heat exchanger, boiler and storage tank were measured at 662, 1073 and 1332 keV of photon energies. Measurements of radiation intensity for various thicknesses of steel were made by using transmission method. The γ-ray intensity were counted by using a Gamma spectrometer that contains a Hyper-pure Germanium (HPGe) detector connected with Multi Channel Analyzer (MCA). The effective numbers of atomic (Z eff ) and electron (N eff ) obtained experimentally were compared by those obtained through theoretical calculation. Both experimental and calculated values of Z eff and N eff were in good agreement. (author)

Study of Electron Cloud E ects in the DAFNE PHI-Factory for the KLOE-2 Run

CERN Document Server

Demma, T

2011-01-01

A strong horizontal instability has been observed in the the DAFNE positron ring since 2003. Experimental observations suggest an electron cloud induced coupled bunbh instability as a possible explanation. Here is reported a simulation study of the electron cloud effects in the positron ring of the DAFNE PHI factory with particular reference to the machine configuration designed for the KLOE-2 experiment.

Effect of additional minor elements on accumulation behavior of point defects under electron irradiation in austenitic stainless steels

International Nuclear Information System (INIS)

Sekio, Yoshihiro; Yamashita, Shinichiro; Takahashi, Heishichiro; Sakaguchi, Norihito

2014-01-01

Addition of minor elements to a base alloy is often applied with the aim of mitigating void swelling by decreasing the vacancy diffusivity and flux which influence vacancy accumulation behavior. However, the comparative evaluations of parameters, such as the diffusivity and flux, between a base alloy and modified alloys with specific additives have not been studied in detail. In this study, type 316 austenitic stainless steel as a base alloy and type 316 austenitic stainless steels modified with vanadium (V) or zirconium (Zr) additions were used to perform evaluations from the changes of widths of the void denuded zone (VDZ) formed near a random grain boundary during electron irradiation because these widths depend on vacancy diffusivity and flux. The formations of VDZs were observed in in-situ observations during electron irradiation at 723 K and the formed VDZ widths were measured from the transmission electron microscopic images after electron irradiation. As a result, the VDZs were formed in both steels without and with V, and respective widths were ∼119 and ∼100 nm. On the other hand, the VDZ formation was not observed clearly in the steel with Zr. From the measured VDZ widths in the steels without and with V addition, the estimated ratio of the vacancy diffusivity in the steel with V to that in the steel without V was about 0.50 and the estimated ratio of the vacancy flux in the steel with V to that in the steel without V was about 0.71. This result suggests that the effect of additional minor elements on vacancy accumulation behaviors under electron irradiation could be estimated from evaluations of the VDZ width changes among steels with and without minor elements. Especially, because void swelling is closely related with the vacancy diffusion process, the VDZ width changes would also be reflected on void swelling behavior. (author)

Electron cloud instabilities in the Proton Storage Ring and Spallation Neutron Source

Directory of Open Access Journals (Sweden)

M. Blaskiewicz

2003-01-01

Full Text Available Electron cloud instabilities in the Los Alamos Proton Storage Ring and those foreseen for the Oak Ridge Spallation Neutron Source are examined theoretically, numerically, and experimentally.

Particle-in-Cell Calculations of the Electron Cloud in the ILC Positron Damping Ring Wigglers

International Nuclear Information System (INIS)

Celata, C.M.; Furman, M.A.; Vay, J.-L.; Grote, D.P.

2007-01-01

The self-consistent code suite WARP-POSINST is being used to study electron cloud effects in the ILC positron damping ring wiggler. WARP is a parallelized, 3D particle-in-cell code which is fully self-consistent for all species. The POSINST models for the production of photoelectrons and secondary electrons are used to calculate electron creation. Mesh refinement and a moving reference frame for the calculation will be used to reduce the computer time needed by several orders of magnitude. We present preliminary results for cloud buildup showing 3D electron effects at the nulls of the vertical wiggler field. First results from a benchmark of WARP-POSINST vs. POSINST are also discussed

Initial Self-Consistent 3D Electron-Cloud Simulations of the LHC Beam with the Code WARP+POSINST

International Nuclear Information System (INIS)

Vay, J; Furman, M A; Cohen, R H; Friedman, A; Grote, D P

2005-01-01

We present initial results for the self-consistent beam-cloud dynamics simulations for a sample LHC beam, using a newly developed set of modeling capability based on a merge [1] of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP [2] and the electron-cloud code POSINST [3]. Although the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms for generation and absorption of the electrons at the walls are based on previously validated models available in POSINST [3, 4

Secondary electron yields of carbon-coated and polished stainless steel

International Nuclear Information System (INIS)

Ruzic, D.; Moore, R.; Manos, D.; Cohen, S.

1982-01-01

To increase the power throughput to a plasma of an existing lower hybrid waveguide, secondary electron production on the walls and subsequent electron multiplication must be reduced. Since carbon has a low secondary electron coefficient (delta), measurements were performed for several UHV compatible carbon coatings (Aquadag/sup X/, vacuum pyrolyzed Glyptal/sup X/, and lamp black deposited by electrophoresis) as a function of primary beam voltage (35 eV to 10 keV), surface roughness (60 through 600 grit mechanical polishing and electropolishing), coating thickness, and angle of incidence (theta). Also measured were uncoated stainless steel, Mo, Cu, Ti, TiC, and ATJ graphite. The yields were obtained by varying the sample bias and measuring the collected current while the samples were in the electron beam of a scanning Auger microprobe. This technique allows delta measurements of Auger characterized surfaces with < or =0.3 mm spatial resolution. Results show delta to have a typical energy dependence, with a peak occurring at 200 to 300 eV for normal incidence, and at higher energy for larger theta. In general, delta increases with theta more for smooth surfaces than for rough ones. Ninety percent of the secondary electrons have energies less than 25 eV. Some carbonized coating and surface treatment combinations give delta/sub max/ = 0.88 +- 0.01 for normal electron beam incidence: a reduction of almost 40% compared to untreated stainless steel

Numerical Simulations for the Beam-Induced Electron Cloud in the LHC Beam Screen

CERN Document Server

Brüning, Oliver Sim

1998-01-01

The following work summarises simulation results obtained at CERN for the beam-induced electron cloud and looks at possible cures for the heat load in the LHC beam screen. The synchrotron radiation in the LHC creates a continuous flow of photoelectrons. These electrons are accelerated by the electric field of the bunch and hit the vacuum chamber on the opposite side of the beam pipe where they crea te secondary electrons which are again accelerated by the next bunch. For a large secondary emission yield the above mechanism leads to an exponential growth of the electron cloud which is limited by space charge forces. The simulations use a two-dimensional mesh for the space charge calculations and include the effect of image charges on the vacuum chamber wall. Depending on the quantum yield for the production of photoelectrons, the secondary emission yield and the reflectivity, the heat load can vary from 0.1 W/m to more than 15 W/m.

Reconciliation of the cloud computing model with US federal electronic health record regulations.

Science.gov (United States)

Schweitzer, Eugene J

2012-01-01

Cloud computing refers to subscription-based, fee-for-service utilization of computer hardware and software over the Internet. The model is gaining acceptance for business information technology (IT) applications because it allows capacity and functionality to increase on the fly without major investment in infrastructure, personnel or licensing fees. Large IT investments can be converted to a series of smaller operating expenses. Cloud architectures could potentially be superior to traditional electronic health record (EHR) designs in terms of economy, efficiency and utility. A central issue for EHR developers in the US is that these systems are constrained by federal regulatory legislation and oversight. These laws focus on security and privacy, which are well-recognized challenges for cloud computing systems in general. EHRs built with the cloud computing model can achieve acceptable privacy and security through business associate contracts with cloud providers that specify compliance requirements, performance metrics and liability sharing.

Surface modification of steels and magnesium alloy by high current pulsed electron beam

Science.gov (United States)

Hao, Shengzhi; Gao, Bo; Wu, Aimin; Zou, Jianxin; Qin, Ying; Dong, Chuang; An, Jian; Guan, Qingfeng

2005-11-01

High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance.

Surface modification of steels and magnesium alloy by high current pulsed electron beam

International Nuclear Information System (INIS)

Hao, Shengzhi; Gao, Bo; Wu, Aimin; Zou, Jianxin; Qin, Ying; Dong, Chuang; An, Jian; Guan, Qingfeng

2005-01-01

High current pulsed electron beam (HCPEB) is now developing as a useful tool for surface modification of materials. When concentrated electron flux transferring its energy into a very thin surface layer within a short pulse time, superfast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved physico-chemical and mechanical properties. This paper presents our research work on surface modification of steels and magnesium alloy with HCPEB of working parameters as electron energy 27 keV, pulse duration ∼1 μs and energy density ∼2.2 J/cm 2 per pulse. Investigations performed on carbon steel T8, mold steel D2 and magnesium alloy AZ91HP have shown that the most pronounced changes of phase-structure state and properties occurring in the near-surface layers, while the thickness of the modified layer with improved microhardness (several hundreds of micrometers) is significantly greater than that of the heat-affected zone. The formation mechanisms of surface cratering and non-stationary hardening effect in depth are discussed based on the elucidation of non-equilibrium temperature filed and different kinds of stresses formed during pulsed electron beam melting treatment. After the pulsed electron beam treatments, samples show significant improvements in measurements of wear and corrosion resistance

Electron-Cloud Pinch Dynamics in Presence of Lattice Magnet Fields

CERN Document Server

Franchetti, G

2011-01-01

The pinch of the electron cloud due to a passing proton bunch was extensively studied in a field free region and in a dipolar magnetic field. For the latter study, a strong field approximation helped to formulate the equations of motion and to understand the complex electron pinch dynamics, which exhibited some similarities with the field-free situation. Here we extend the analysis to the case of electron pinch in quadrupoles and in sextupoles. We discuss the limits of validity for the strong field approximation and we evaluate the relative magnitude of the peak tune shift along the bunch expected for the different fields.

TRIP steel microstructure visualized by slow and very slow electrons

Czech Academy of Sciences Publication Activity Database

Mikmeková, Šárka; Yamada, K.; Noro, H.

2013-01-01

Roč. 62, č. 6 (2013), s. 589-596 ISSN 2050-5698 R&D Projects: GA TA ČR TE01020118 Institutional support: RVO:68081731 Keywords : SLEEM * SEM * crystallographic contrast * surface sensitivity * multi-phase steels * cathode lens mode Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Research on electron beam welding technology of steel HR-4

International Nuclear Information System (INIS)

Guo Peng; Guan Kai

2001-01-01

The electron beam weldability of HR- 4 steels (J75 and J90) is studied and the welding parameters needed for design and usage are presented. The assessment on the effect of mechanical properties by different processing order of welding and heat-treatment is made

Reconciliation of the cloud computing model with US federal electronic health record regulations

Science.gov (United States)

2011-01-01

Cloud computing refers to subscription-based, fee-for-service utilization of computer hardware and software over the Internet. The model is gaining acceptance for business information technology (IT) applications because it allows capacity and functionality to increase on the fly without major investment in infrastructure, personnel or licensing fees. Large IT investments can be converted to a series of smaller operating expenses. Cloud architectures could potentially be superior to traditional electronic health record (EHR) designs in terms of economy, efficiency and utility. A central issue for EHR developers in the US is that these systems are constrained by federal regulatory legislation and oversight. These laws focus on security and privacy, which are well-recognized challenges for cloud computing systems in general. EHRs built with the cloud computing model can achieve acceptable privacy and security through business associate contracts with cloud providers that specify compliance requirements, performance metrics and liability sharing. PMID:21727204

High-accuracy diagnostic tool for electron cloud observation in the LHC based on synchronous phase measurements

CERN Document Server

Esteban Müller, J F; Shaposhnikova, E; Valuch, D; Mastoridis, T

2014-01-01

Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results clearly show the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all...

Secondary Electron Yield Measurements and Groove Chambers Tests in the PEP-II Beam Line Straights Sections

International Nuclear Information System (INIS)

Pivi, M

2008-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings and it is expected to be a limiting factor in the performance of the positron Damping Ring (DR) of future Linear Colliders such as ILC and CLIC [1, 2]. In the Positron Low Energy Ring (LER) of the PEP-II accelerator, we have installed vacuum chambers with rectangular grooves in a straight magnetic-free section to test this promising possible electron cloud mitigation technique. We have also installed a special chamber to monitor the secondary electron yield of TiN and TiZrV (NEG) coating, Copper, Stainless Steel and Aluminum under the effect of electron and photon conditioning in situ in the beam line. In this paper, we describe the ongoing R and D effort to mitigate the electron cloud effect for the ILC damping ring, the latest results on in situ secondary electron yield conditioning and recent update on the groove tests in PEP-II

Study of Deformation Phenomena in TRIP/TWIP Steels by Acoustic Emission and Scanning Electron Microscopy

Science.gov (United States)

Linderov, M. L.; Segel, C.; Weidner, A.; Biermann, H.; Vinogradov, A. Yu.

2018-04-01

Modern metastable steels with TRIP/TWIP effects have a unique set of physical-mechanical properties. They combine both high-strength and high-plasticity characteristics, which is governed by processes activated during deformation, namely, twinning, the formation of stacking faults, and martensitic transformations. To study the behavior of these phenomena in CrMnNi TRIP/TWIP steels and stainless CrNiMo steel, which does not have these effects in the temperature range under study, we used the method of acoustic emission and modern methods of signal processing, including the cluster analysis of spectral-density functions. The results of this study have been compared with a detailed microstructural analysis performed with a scanning electron microscope using electron backscatter diffraction (EBSD).

Surface Alloying of SUS 321 Chromium-Nickel Steel by an Electron-Plasma Process

Science.gov (United States)

Ivanov, Yu. F.; Teresov, A. D.; Petrikova, E. A.; Krysina, O. V.; Ivanova, O. V.; Shugurov, V. V.; Moskvin, P. V.

2017-07-01

The mechanisms of forming nanostructured, nanophase layers are revealed and analyzed in austenitic steel subjected to surface alloying using an electron-plasma process. Nanostructured, nanophase layers up to 30 μm in thickness were formed by melting of the film/substrate system with an electron beam generated by a SOLO facility (Institute of High Current Electronics, SB RAS), Tomsk), which ensured crystallization and subsequent quenching at the cooling rates within the range 105-108 K/s. The surface was modified with structural stainless steel specimens (SUS 321 steel). The film/substrate system (film thickness 0.5 μm) was formed by a plasma-assisted vacuum-arc process by evaporating a cathode made from a sintered pseudoalloy of the following composition: Zr - 6 at.% Ti - 6 at.% Cu. The film deposition was performed in a QUINTA facility equipped with a PINK hot-cathode plasma source and DI-100 arc evaporators with accelerated cooling of the process cathode, which allowed reducing the size and fraction of the droplet phase in the deposited film. It is found that melting of the film/substrate system (Zr-Ti-Cu)/(SUS 321 steel) using a high-intensity pulsed electron beam followed by the high-rate crystallization is accompanied by the formation of α-iron cellular crystallization structure and precipitation of Cr2Zr, Cr3C2 and TiC particles on the cell boundaries, which as a whole allowed increasing microhardness by a factor of 1.3, Young's modulus - by a factor of 1.2, wear resistance - by a factor of 2.7, while achieving a three-fold reduction in the friction coefficient.

Structure and properties of the tool steel after electron beam treatment and following tempering

International Nuclear Information System (INIS)

Kozyr', I.G.; Borodin, R.V.; Voropaev, A.V.; Potapov, V.G.

1998-01-01

The possibility of changing the surface structure of chromium tool steel has been considered. The given properties were reached through the surface remelting by electron beam with following tempering of strengthened layer. The found distinguished zones with different structure and properties are formed as the result of this treatment. It is shown that for hipereutectoid steel the thermal furnace annealing at 300 deg C is necessary for strengthened surface layer forming after electron beam remelting. The same result can be had by means of short-term heating with electronic beam up to higher temperatures, but is not higher A 1 . The evaluation of temperature fields was carried out by numerical solution of nonstationary heat conductivity equation

Electron-cloud simulation results for the SPS and recent results for the LHC

International Nuclear Information System (INIS)

Furman, M.A.; Pivi, M.T.F.

2002-01-01

We present an update of computer simulation results for some features of the electron cloud at the Large Hadron Collider (LHC) and recent simulation results for the Super Proton Synchrotron (SPS). We focus on the sensitivity of the power deposition on the LHC beam screen to the emitted electron spectrum, which we study by means of a refined secondary electron (SE) emission model recently included in our simulation code

Time-resolved Shielded-Pickup Measurements and Modeling of Beam Conditioning Effects on Electron Cloud Buildup at CesrTA

CERN Document Server

Crittenden, J A; Liu, X; Palmer, M A; Santos, S; Sikora, J P; Kato, S; Calatroni, S; Rumolo, G

2012-01-01

The Cornell Electron Storage Ring Test Accelerator program includes investigations into electron cloud buildup in vacuum chambers with various coatings. Two 1.1-mlong sections located symmetrically in the east and west arc regions are equipped with BPM-like pickup detectors shielded against the direct beam-induced signal. They detect cloud electrons migrating through an 18-mm-diameter pattern of 0.76 mm-diameter holes in the top of the chamber. A digitizing oscilloscope is used to record the signals, providing time-resolved information on cloud development. We present new measurements of the effect of beam conditioning on a newly-installed amorphous carbon coated chamber, as well as on an extensively conditioned chamber with a diamond-like carbon coating. The ECLOUD modeling code is used to quantify the sensitivity of these measurements to model parameters, differentiating between photoelectron and secondary-electron production processes.

Molecular clouds near supernova remnants

International Nuclear Information System (INIS)

Wootten, H.A.

1978-01-01

The physical properties of molecular clouds near supernova remnants were investigated. Various properties of the structure and kinematics of these clouds are used to establish their physical association with well-known remmnants. An infrared survey of the most massive clouds revealed embedded objects, probably stars whose formation was induced by the supernova blast wave. In order to understand the relationship between these and other molecular clouds, a control group of clouds was also observed. Excitation models for dense regions of all the clouds are constructed to evaluate molecular abundances in these regions. Those clouds that have embedded stars have lower molecular abundances than the clouds that do not. A cloud near the W28 supernova remnant also has low abundances. Molecular abundances are used to measure an important parameter, the electron density, which is not directly observable. In some clouds extensive deuterium fractionation is observed which confirms electron density measurements in those clouds. Where large deuterium fractionation is observed, the ionization rate in the cloud interior can also be measured. The electron density and ionization rate in the cloud near W28 are higher than in most clouds. The molecular abundances and electron densities are functions of the chemical and dynamical state of evolution of the cloud. Those clouds with lowest abundances are probably the youngest clouds. As low-abundance clouds, some clouds near supernova remnants may have been recently swept from the local interstellar material. Supernova remnants provide sites for star formation in ambient clouds by compressing them, and they sweep new clouds from more diffuse local matter

Nano structure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

International Nuclear Information System (INIS)

Zhang, K.M.; Zou, J.X.; Zou, J.X.; Grosdidier, T.; Zou, J.X.; Grosdidier, T.; Grosdidier, T.

2013-01-01

The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nano structure formations of steels by using a low energy high pulsed electron beam (LEHCPEB) treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels

Simulation study of electron cloud induced instabilities and emittance growth for the CERN Large Hadron Collider proton beam

CERN Document Server

Benedetto, Elena; Schulte, Daniel; Rumolo, Giovanni

2005-01-01

The electron cloud may cause transverse single-bunch instabilities of proton beams such as those in the Large Hadron Collider (LHC) and the CERN Super Proton Synchrotron (SPS). We simulate these instabilities and the consequent emittance growth with the code HEADTAIL, which models the turn-by-turn interaction between the cloud and the beam. Recently some new features were added to the code, in particular, electric conducting boundary conditions at the chamber wall, transverse feedback, and variable beta functions. The sensitivity to several numerical parameters has been studied by varying the number of interaction points between the bunch and the cloud, the phase advance between them, and the number of macroparticles used to represent the protons and the electrons. We present simulation results for both LHC at injection and SPS with LHC-type beam, for different electron-cloud density levels, chromaticities, and bunch intensities. Two regimes with qualitatively different emittance growth are observed: above th...

Simulation and analysis of TE wave propagation for measurement of electron cloud densities in particle accelerators

Energy Technology Data Exchange (ETDEWEB)

Sonnad, Kiran G., E-mail: kgs52@cornell.edu [CLASSE, Cornell University, Ithaca, NY (United States); Hammond, Kenneth C. [Department of Physics, Harvard University, Cambridge, MA (United States); Schwartz, Robert M. [CLASSE, Cornell University, Ithaca, NY (United States); Veitzer, Seth A. [Tech-X Corporation, Boulder, CO (United States)

2014-08-01

The use of transverse electric (TE) waves has proved to be a powerful, noninvasive method for estimating the densities of electron clouds formed in particle accelerators. Results from the plasma simulation program VSim have served as a useful guide for experimental studies related to this method, which have been performed at various accelerator facilities. This paper provides results of the simulation and modeling work done in conjunction with experimental efforts carried out at the Cornell electron storage ring “Test Accelerator” (CESRTA). This paper begins with a discussion of the phase shift induced by electron clouds in the transmission of RF waves, followed by the effect of reflections along the beam pipe, simulation of the resonant standing wave frequency shifts and finally the effects of external magnetic fields, namely dipoles and wigglers. A derivation of the dispersion relationship of wave propagation for arbitrary geometries in field free regions with a cold, uniform cloud density is also provided.

An integrated electron and optical metallographic procedure for the identification of precipitate phases in type 316 stainless steel

International Nuclear Information System (INIS)

Slattery, G.F.; O'Riordan, P.; Lambert, M.E.; Green, S.M.

1981-01-01

A sequential and integrated metallographic procedure has been developed and successfully employed to differentiate between carbide, sigma, chi, Laves and ferrite phases which are commonly encountered in type 316 austenitic steel. The experimental techniques of optical and electron microscopy to identify these phases have been outlined and provide a rapid and convenient method of characterizing the microstructure of the steel. The techniques sequence involves selective metallographic etching, Nomarski interference microscopy, scanning electron microscopy, energy dispersive microanalysis, transmission electron microscopy and electron diffraction. (author)

Multipactor for e-cloud diagnostics

CERN Document Server

Costa Pinto, P; Edwards, P; Holz, M; Taborelli, M

2012-01-01

Electron cloud in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY). SEY of small samples can be measured in the laboratory. Verifying the performance of long pipes is more complex, since it requires their insertion in the accelerator and the subsequent measurement of the beam induced pressure rise. RF induced multipacting in a coaxial waveguide configuration is proposed as a test before insertion in the machine. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed through a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to cyclotron resonances for given magnetic fields. Preliminary results show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power...

Surface hardening of 30CrMnSiA steel using continuous electron beam

Science.gov (United States)

Fu, Yulei; Hu, Jing; Shen, Xianfeng; Wang, Yingying; Zhao, Wansheng

2017-11-01

30CrMnSiA high strength low alloy (HSLA) carbon structural steel is typically applied in equipment manufacturing and aerospace industries. In this work, the effects of continuous electron beam treatment on the surface hardening and microstructure modifications of 30CrMnSiA are investigated experimentally via a multi-purpose electron beam machine Pro-beam system. Micro hardness value in the electron beam treated area shows a double to triple increase, from 208 HV0.2 on the base metal to 520 HV0.2 on the irradiated area, while the surface roughness is relatively unchanged. Surface hardening parameters and mechanisms are clarified by investigation of the microstructural modification and the phase transformation both pre and post irradiation. The base metal is composed of ferrite and troostite. After continuous electron beam irradiation, the micro structure of the electron beam hardened area is composed of acicular lower bainite, feathered upper bainite and part of lath martensite. The optimal input energy density for 30CrMnSiA steel in this study is of 2.5 kJ/cm2 to attain the proper hardened depth and peak hardness without the surface quality deterioration. When the input irradiation energy exceeds 2.5 kJ/cm2 the convective mixing of the melted zone will become dominant. In the area with convective mixing, the cooling rate is relatively lower, thus the micro hardness is lower. The surface quality will deteriorate. Chemical composition and surface roughness pre and post electron beam treatment are also compared. The technology discussed give a picture of the potential of electron beam surface treatment for improving service life and reliability of the 30CrMnSiA steel.

Simulation study of electron cloud build up in the SPS MKD kickers

CERN Document Server

Rumolo, G

2009-01-01

During the 2008 run, an unusual behavior characterizing pressure and temperature increase in some of the dump kickers of the SPS was noticed. In particular, it was observed that 1) the MKDV2 kicker would exhibit maximum heating with 75 ns spaced LHC beams and 2) the pressure rise was specially critical in MKDV1 in presence of 50 ns spaced LHC beams [1]. While the anomalous heating of MKDV2 with 75 ns beams could be tentatively explained by the denser beam current spectrum that would more likely hit one of the kicker impedance peaks, the fast pressure rise in MKDV1 with 50 ns spaced beams was ascribed to a surface effect, namely beam induced multipacting leading to electron cloud formation. This report summarizes a simulation study that was done in order to check whether the electron cloud behavior in the dump kickers could explain the experimental observations.

Electron cloud in various kinds of magnetic field of BEPCII

International Nuclear Information System (INIS)

Liu Yudong; Guo Zhiyuan; Qin Qing; Wang Jiuqing

2006-01-01

Electron cloud instability (ECI) may take place in a positron storage ring when the machine is operated with a multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPCII, a programme which is different from the other simulation codes has been developed. Because of the distance between dipole magnet and sextupole, the quadrupole magnet of BEPCII is very short, much of the photoelectrons can be produced and can move in magnetic fields. The motion of electrons in various kinds of magnetic fields is studied in detail, especially for the solenoid field which will be wound in the vacuum pipe of BEPCII. Simulation shows that the solenoid field is very effective to confine the electrons to the vicinity of the vacuum chamber wall and to make an electron free region at the vacuum pipe centre. (authors)

Microstructure of steel X 20 Cr 13 in the electron microscopical picture

International Nuclear Information System (INIS)

Gesatzke, W.

1982-01-01

The tempered microstructure of the steel X 20 Cr 13 is described by an electron microscopical overall picture and additional information is gained which would not be possible with the optical microscope. The large transmission area permits one to quantitatively evaluate a microstructure component which due to its small size can only be measured with electron microscope pictures. (orig.) [de

Electron Cloud Observations during LHC Operation with 25 ns Beams

CERN Document Server

Li, Kevin; Iadarola, Giovanni; Mether, Lotta; Romano, Annalisa; Rumolo, Giovanni; Schenk, Michael

2016-01-01

While during the Run 1 (2010-2012) of the Large Hadron Collider (LHC) most of the integrated luminosity was produced with 50 ns bunch spacing, for the Run 2 start-up (2015) it was decided to move to the nominal bunch spacing of 25 ns. As expected, with this beam configuration strong electron cloud effects were observed in the machine, which had to be mitigated with dedicated 'scrubbing' periods at injection energy. This enabled to start the operation with 25 ns beams at 6.5 TeV, but e-cloud effects continued to pose challenges while gradually increasing the number of circulating bunch trains. This contribution will review the encountered limitations and the mitigation measures that where put in place and will discuss possible strategies for further performance gain.

Hydrogen assisted stress-cracking behaviour of electron beam welded supermartensitic stainless steel weldments

International Nuclear Information System (INIS)

Bala Srinivasan, P.; Sharkawy, S.W.; Dietzel, W.

2004-01-01

Supermartensitic stainless steel (SMSS) grades are gaining popularity as an alternate material to duplex and super duplex stainless steels for applications in oil and gas industries. The weldability of these steels, though reported to be better when compared to conventional martensitic stainless steels, so far has been addressed with duplex stainless steel electrodes/fillers. This work addresses the stress-cracking behaviour of weldments of a high-grade supermartensitic stainless steel (11% Cr, 6.5% Ni and 2% Mo) in the presence of hydrogen. Welds were produced with matching consumables, using electron beam welding (EBW) process. Weldments were subjected to slow strain rate tests in 0.1 M NaOH solution, with introduction of hydrogen into the specimens by means of potentiostatic cathodic polarisation at a potential of -1200 mV versus Ag/AgCl electrode. Reference tests were performed in air for comparison, and the results suggest that both the SMSS base material and the EB weld metal are susceptible to embrittlement under the conditions of hydrogen charging

Nanostructure Formations and Improvement in Corrosion Resistance of Steels by Means of Pulsed Electron Beam Surface Treatment

Directory of Open Access Journals (Sweden)

K. M. Zhang

2013-01-01

Full Text Available The corrosion of steels has long been the topic for materials scientists. It is established that surface treatment is an efficient way to improve the corrosion resistance of steels without changing the bulk properties and with low costs. In the present paper, different kinds of surface treatment techniques for steels are briefly reviewed. In particular, the surface modification involving nanostructure formations of steels by using a low energy high pulsed electron beam (LEHCPEB treatment is lightened in the case of an AISI 316L stainless steel and D2 steel. The overall results demonstrate the high potential of the LEHCPEB technique for improving the corrosion performance of steels.

Investigation into electron cloud effects in the International Linear Collider positron damping ring

Energy Technology Data Exchange (ETDEWEB)

Crittenden, J. A.; Conway, J.; Dugan, G. F.; Palmer, M. A.; Rubin, D. L.; Shanks, J.; Sonnad, K. G.; Boon, L.; Harkay, K.; Ishibashi, T.; Furman, M. A.; Guiducci, S.; Pivi, M. T. F.; Wang, L.

2014-03-01

We report modeling results for electron cloud buildup and instability in the International Linear Collider positron damping ring. Updated optics, wiggler magnets, and vacuum chamber designs have recently been developed for the 5 GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effects of diffuse and specular photon scattering on the interior surfaces of the vacuum chamber. The results provide input to the cloud buildup simulations for the various magnetic field regions of the ring. The modeled cloud densities thus obtained are used in the instability threshold calculations. We conclude that the mitigation techniques employed in this model will suffice to allow operation of the damping ring at the design operational specifications

On a possibility of creation of positive space charge cloud in a system with magnetic insulation of electrons

International Nuclear Information System (INIS)

Goncharov, A.A.; Dobrovol'skii, A.M.; Dunets, S.P.; Evsyukov, A.N.; Protsenko, I.M.

2009-01-01

We describe a new approach for creation an effective, low-cost, low-maintenance axially symmetric plasma optical tools for focusing and manipulating high-current beams of negatively charged particles, electrons and negative ions. This approach is based on fundamental plasma optical concept of magnetic insulation of electrons and non-magnetized positive ions providing creation of controlled uncompensated cloud of the space charge. The axially symmetric electrostatic plasma optical lens is well-known and well developed tool where this concept is used successfully. This provides control and focusing high-current positive ion beams in wide range of parameters. Here for the first time we present optimistic experimental results describing the application of an idea of magnetic insulation of electrons for generation of the stable cloud of positive space charge by focusing onto axis the converging stream of heavy ions produced by circular accelerator with closed electron drift. The estimations of a maximal concentration of uncompensated cloud of positive ions are also made

Qualitative analysis of the e-cloud formation

International Nuclear Information System (INIS)

Heifets, Samuel A

2002-01-01

The qualitative analysis of the electron cloud formation is presented. Two mechanisms of the cloud formation, generation of jets of primary photo-electrons and thermalization of electrons in the electron cloud, are analyzed and compared with simulations for the NLC damping ring [1

Wake Field of the e-Cloud

International Nuclear Information System (INIS)

Heifets, Samuel A

2001-01-01

The wake field of the cloud is derived analytically taking into account the finite size of the cloud and nonlinearity of the electron motion. The analytic expression for the effective transverse wake field caused by the electron cloud in a positron storage ring is derived. The derivation includes the frequency spread in the cloud, which is the main effect of the nonlinearity of electron motion in the cloud. This approach allows calculation of the Q-factor and study the tune spread in a bunch

Proceedings of Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects

International Nuclear Information System (INIS)

Cimino, R; Rumolo, Giovanni; Zimmermann, Frank

2013-01-01

This report contains the Proceedings of the Joint INFN-Frascati, INFN-Pisa, CERN-LER and EuCARD-AccNet Mini-Workshop on Electron-Cloud Effects, “ECLOUD12”, held at La Biodola, Isola d’Elba, from 5 to 9 June 2012. The ECLOUD12 workshop reviewed many recent electron-cloud (EC) observations at existing storage rings, EC predictions for future accelerators, electron-cloud studies at DAFNE, EC mitigation by clearing electrodes and graphite/carbon coatings, modeling of incoherent EC effects, self-consistent simulations, synergies with other communities like the Valencia Space Consortium and the European Space Agency. ECLOUD12 discussed new EC observations at existing machines including LHC, CesrTA, PETRA-3, J-PARC, and FNAL MI; latest experimental efforts to characterize the EC – including EC diagnostics, experimental techniques, mitigation techniques such as coating and conditioning, advanced chemical and physical analyses of various vacuum-chamber surfaces, beam instabilities and emittance growth –; the status of EC physics models and (new, more versatile and additional) simulation codes and their comparison with recently acquired experimental data; and the mitigation requirements and potential performance limitations imposed by the EC on upgraded and future machines, including HL-LHC, FAIR, ILC, Project-X, SuperB and SuperKEKB. A dedicated session addressed problems related to RF breakdown and multipacting for space applications. A number of open questions and future R&D needs were identified

Simulation of Electron-Cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data

CERN Document Server

Maury Cuna, H; Rumolo, G; Tavian, L; Zimmermann, F

2011-01-01

The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters. In particular, we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011.

Analysis of the security and privacy requirements of cloud-based electronic health records systems.

Science.gov (United States)

Rodrigues, Joel J P C; de la Torre, Isabel; Fernández, Gonzalo; López-Coronado, Miguel

2013-08-21

The Cloud Computing paradigm offers eHealth systems the opportunity to enhance the features and functionality that they offer. However, moving patients' medical information to the Cloud implies several risks in terms of the security and privacy of sensitive health records. In this paper, the risks of hosting Electronic Health Records (EHRs) on the servers of third-party Cloud service providers are reviewed. To protect the confidentiality of patient information and facilitate the process, some suggestions for health care providers are made. Moreover, security issues that Cloud service providers should address in their platforms are considered. To show that, before moving patient health records to the Cloud, security and privacy concerns must be considered by both health care providers and Cloud service providers. Security requirements of a generic Cloud service provider are analyzed. To study the latest in Cloud-based computing solutions, bibliographic material was obtained mainly from Medline sources. Furthermore, direct contact was made with several Cloud service providers. Some of the security issues that should be considered by both Cloud service providers and their health care customers are role-based access, network security mechanisms, data encryption, digital signatures, and access monitoring. Furthermore, to guarantee the safety of the information and comply with privacy policies, the Cloud service provider must be compliant with various certifications and third-party requirements, such as SAS70 Type II, PCI DSS Level 1, ISO 27001, and the US Federal Information Security Management Act (FISMA). Storing sensitive information such as EHRs in the Cloud means that precautions must be taken to ensure the safety and confidentiality of the data. A relationship built on trust with the Cloud service provider is essential to ensure a transparent process. Cloud service providers must make certain that all security mechanisms are in place to avoid unauthorized access

Microstructural Characterization and Mechanical Properties of Electron Beam Welded Joint of High Strength Steel Grade S690QL

Directory of Open Access Journals (Sweden)

Błacha S.

2016-06-01

Full Text Available In the paper the results of metallographic examination and mechanical properties of electron beam welded joint of quenched and tempered steel grade S690QL are presented. Metallographic examination revealed that the concentrated electron beam significantly affect the changes of microstructure in the steel. Parent material as a delivered condition (quenched and tempered had a bainitic-martensitic microstructure at hardness about 290 HV0.5. After welding, the microstructure of heat affected zone is composed mainly of martensite (in the vicinity of the fusion line of hardness 420 HV0.5. It should be noted, however, that the microstructure of steel in the heat affected zone varies with the distance from the fusion line. The observed microstructural changes were in accordance with the CCT-S transformation diagram for the examined steel.

Improving the properties of stainless steel electron-beam welds by laser treatment

International Nuclear Information System (INIS)

Wu Xueyi; Zhou Changchi

1991-10-01

For improving the properties of corrosion resistance of stainless steel, which is widely used in nuclear engineering, the technological test on rapid fusing and setting formed by using laser treatment in electron-beam welds on stainless steel was investigated and the analytical results of welding structure and properties were reported. The experimental results show that after laser treatment more finegrained structure in the surface of the welding centreline and welding heat-affected zone was observed. Segregation of chemical composition was reduced. Plasticity and corrosion resistance in the welding zone was increased. Intergranular corrosion of heat-affected zone was improved

A preliminary comparative study of the electron-cloud effect for the PSR, ISIS, and the ESS

International Nuclear Information System (INIS)

Furman, M.A.; Pivi, M.T.F.

2003-01-01

We present preliminary electron-cloud simulation results for the Proton Storage Ring (PSR) at LANL, ISIS at RAL, and the European Spallation Source (ESS). For each storage ring, we simulate the build-up and dissipation of the electron cloud (EC) in a representative field-free section of the vacuum chamber. For all three cases, we choose the same residual gas temperature, secondary emission yield (SEY), and secondary emission spectrum. Other variables such as proton loss rate, bunch profile, intensity and energy, residual gas pressure and chamber geometry, are set at the corresponding values for each machine. Under these assumptions, we conclude that, of the three machines, the PSR is the most severely affected by the electron cloud effect (ECE), followed by the ESS, with ISIS a distant third. We illustrate a strong sensitivity of the ECE to the longitudinal bunch profile by choosing two different shapes for the case of the PSR, and a weak sensitivity to residual gas pressure. This preliminary study does not address the ECE in other regions of the machine, nor the beam instability that might arise from the EC

IMPURITY SEGREGATION OF STAINLESS STEEL STUDIED BY ATOM-PROBE AND AUGER ELECTRON SPECTROSCOPY

OpenAIRE

Koguchi , Y.; Takahashi , K.; Ishikawa , Y.

1987-01-01

The surface compositions of type 304 stainless steel heated in vacuum at 600-900°C were determined by an atom-probe and Auger electron spectroscopic analysis. In addition to enrichment and depletion of alloying elements in the surface of the stainless steel, segregation of impurity elements such as carbon, nitrogen, phosphorus and sulfur is known to occur. In this paper the atom-probe was used to measure the impurity segregation in the grains as well as in the grain boundary while the AES was...

NAFFS: network attached flash file system for cloud storage on portable consumer electronics

Science.gov (United States)

Han, Lin; Huang, Hao; Xie, Changsheng

Cloud storage technology has become a research hotspot in recent years, while the existing cloud storage services are mainly designed for data storage needs with stable high speed Internet connection. Mobile Internet connections are often unstable and the speed is relatively low. These native features of mobile Internet limit the use of cloud storage in portable consumer electronics. The Network Attached Flash File System (NAFFS) presented the idea of taking the portable device built-in NAND flash memory as the front-end cache of virtualized cloud storage device. Modern portable devices with Internet connection have built-in more than 1GB NAND Flash, which is quite enough for daily data storage. The data transfer rate of NAND flash device is much higher than mobile Internet connections[1], and its non-volatile feature makes it very suitable as the cache device of Internet cloud storage on portable device, which often have unstable power supply and intermittent Internet connection. In the present work, NAFFS is evaluated with several benchmarks, and its performance is compared with traditional network attached file systems, such as NFS. Our evaluation results indicate that the NAFFS achieves an average accessing speed of 3.38MB/s, which is about 3 times faster than directly accessing cloud storage by mobile Internet connection， and offers a more stable interface than that of directly using cloud storage API. Unstable Internet connection and sudden power off condition are tolerable, and no data in cache will be lost in such situation.

Microstructural characterization of atom clusters in irradiated pressure vessel steels and model alloys

International Nuclear Information System (INIS)

Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

1993-01-01

In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs

Microstructural characterization of atom clusters in irradiated pressure vessel steels and model alloys

Energy Technology Data Exchange (ETDEWEB)

Auger, P; Pareige, P [Rouen Univ., 76 - Mont-Saint-Aignan (France); Akamatsu, M; Van Duysen, J C [Electricite de France (EDF), 77 - Ecuelles (France)

1994-12-31

In order to characterize the microstructural evolution of iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions, and, for comparison, low copper model alloys irradiated with neutrons and electrons, have been studied through small angle neutron scattering and atom probe experiments. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex; solute atoms such as Ni, Mn and Si, sometimes associated with Cu, segregate as ``clouds`` more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs.

Electronic Health Records in the Cloud: Improving Primary Health Care Delivery in South Africa.

Science.gov (United States)

Cilliers, Liezel; Wright, Graham

2017-01-01

In South Africa, the recording of health data is done manually in a paper-based file, while attempts to digitize healthcare records have had limited success. In many countries, Electronic Health Records (EHRs) has developed in silos, with little or no integration between different operational systems. Literature has provided evidence that the cloud can be used to 'leapfrog' some of these implementation issues, but the adoption of this technology in the public health care sector has been very limited. This paper aims to identify the major reasons why the cloud has not been used to implement EHRs for the South African public health care system, and to provide recommendations of how to overcome these challenges. From the literature, it is clear that there are technology, environmental and organisational challenges affecting the implementation of EHRs in the cloud. Four recommendations are provided that can be used by the National Department of Health to implement EHRs making use of the cloud.

Electron Cloud induced instabilities in the Fermilab Main Injector(MI) for the High Intensity Neutrino Source (HINS) project

International Nuclear Information System (INIS)

Sonnad, Kiran G.; Furman, Miguel A.; Vay, Jean-Luc; Venturini, Marco; Celata, Christine; Grote, David

2006-01-01

The electrostatic particle-in-cell codeWARP is currently being expanded in order to study electron cloud effects on the dynamics of the beam in storage rings. Results for the Fermilab main injector (MI) show the existence of a threshold in the electron density beyond which there is rapid emittance growth. The Fermilab MI is being considered for an upgrade as part of the high intensity neutrino source (HINS) effort, which will result in a significant increasing of the bunch intensity relative to its present value, placing it in a regime where electron-cloud effects are expected to become important. Various results from the simulations using WARP are discussed here

Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

2008-01-01

Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

Directory of Open Access Journals (Sweden)

Robert J. Macek

2008-01-01

Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

ELECTRON CLOUD AT COLLIMATOR AND INJECTION REGION OF THE SPALLATION NEUTRON SOURCE ACCUMULATOR RING

International Nuclear Information System (INIS)

WANG, L.; HSEUH, H.-C.; LEE, Y.Y.; RAPARIA, D.; WEI, J.; COUSINEAU, S.

2005-01-01

The beam loss along the Spallation Neutron Source's accumulator ring is mainly located at the collimator region and injection region. This paper studied the electron cloud build-up at these two regions with the three-dimension program CLOUDLAND

Beam-Beam Interaction, Electron Cloud and Intrabeam Scattering for Proton Super-bunches

CERN Document Server

Ruggiero, F; Rumolo, Giovanni; Papaphilippou, Y

2003-01-01

Super-bunches are long bunches with a flat longitudinal profile, which could potentially increase the LHC luminosity in a future upgrade. We present example parameters and discuss a variety of issues related to such superbunches, including beam-beam tune shift, tune footprints, crossing schemes, luminosity, intrabeam scattering, and electron cloud. We highlight the benefits, disadvantages and open questions.

Mitigation of the electron-cloud effect in the PSR and SNS protonstorage rings by tailoring the bunch profile

CERN Document Server

Pivi, M T

2003-01-01

For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure.

MITIGATION OF THE ELECTRON-CLOUD EFFECT IN THE PSR AND SNS PROTONSTORAGE RINGS BY TAILORING THE BUNCH PROFILE

International Nuclear Information System (INIS)

Pivi, Mauro T F

2003-01-01

For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

Electron transfer mediators accelerated the microbiologically influence corrosion against carbon steel by nitrate reducing Pseudomonas aeruginosa biofilm.

Science.gov (United States)

Jia, Ru; Yang, Dongqing; Xu, Dake; Gu, Tingyue

2017-12-01

Electron transfer is a rate-limiting step in microbiologically influenced corrosion (MIC) caused by microbes that utilize extracellular electrons. Cross-cell wall electron transfer is necessary to transport the electrons released from extracellular iron oxidation into the cytoplasm of cells. Electron transfer mediators were found to accelerate the MIC caused by sulfate reducing bacteria. However, there is no publication in the literature showing the effect of electron transfer mediators on MIC caused by nitrate reducing bacteria (NRB). This work demonstrated that the corrosion of anaerobic Pseudomonas aeruginosa (PAO1) grown as a nitrate reducing bacterium biofilm on C1018 carbon steel was enhanced by two electron transfer mediators, riboflavin and flavin adenine dinucleotide (FAD) separately during a 7-day incubation period. The addition of either 10ppm (w/w) (26.6μM) riboflavin or 10ppm (12.7μM) FAD did not increase planktonic cell counts, but they increased the maximum pit depth on carbon steel coupons considerably from 17.5μm to 24.4μm and 25.0μm, respectively. Riboflavin and FAD also increased the specific weight loss of carbon steel from 2.06mg/cm 2 to 2.34mg/cm 2 and 2.61mg/cm 2 , respectively. Linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization curves all corroborated the pitting and weight loss data. Copyright © 2017 Elsevier B.V. All rights reserved.

The development of PVC-laminated steel sheet by an electron beam curing method

International Nuclear Information System (INIS)

Masuhara, Ken-ichi; Koshiishi, Kenji; Tomosue, Takao; Mori, Koji; Honma, Nobuyuki

1988-01-01

Polyvinyl chloride (PVC) film-laminated steel sheets are used for household electric appliances and building materials. Those are produced usually by pressing a PVC film onto a steel sheet imediately after a themosetting adhesive has been applied to the sheet and curing. However, a major problem of this method is that the appearance of the PVC films such as gloss and embossment changes during pressing due to the heat that is required for causing bonding, therefore, the development of an adhesive which can be cured at lower temperature is necessary. Nisshin Steel Co., Ltd. has developed PVC film-laminated steel sheets for which electron beam (EB) curable adhesives are used to overcome this problem. The advantage of these adhesives is that they can be quickly cured at room temperature. The production procedure of PVC-laminated steel sheets by EB curing is outlined. But this method has encountered two problems: poor adhesion between substrates and adhesive due to the residual stress, and the deterioration of the PVC films due to EB irradiation. EB curable adhesives are mainly composed of acrylic ester oligomers and monomers, and thier adhesion was improved by organic pretreatment. On the other hand, EB-proof PVC films were developed. The general properties of PVC-laminated steel sheets produced by EB curing are reported. (K.I.)

A spherical electron cloud hopping model for studying product branching ratios of dissociative recombination.

Science.gov (United States)

Yu, Hua-Gen

2008-05-21

A spherical electron cloud hopping (SECH) model is proposed to study the product branching ratios of dissociative recombination (DR) of polyatomic systems. In this model, the fast electron-captured process is treated as an instantaneous hopping of a cloud of uniform spherical fractional point charges onto a target M+q ion (or molecule). The sum of point charges (-1) simulates the incident electron. The sphere radius is determined by a critical distance (Rc eM) between the incoming electron (e-) and the target, at which the potential energy of the e(-)-M+q system is equal to that of the electron-captured molecule M+q(-1) in a symmetry-allowed electronic state with the same structure as M(+q). During the hopping procedure, the excess energies of electron association reaction are dispersed in the kinetic energies of M+q(-1) atoms to conserve total energy. The kinetic energies are adjusted by linearly adding atomic momenta in the direction of driving forces induced by the scattering electron. The nuclear dynamics of the resultant M+q(-1) molecule are studied by using a direct ab initio dynamics method on the adiabatic potential energy surface of M+q(-1), or together with extra adiabatic surface(s) of M+q(-1). For the latter case, the "fewest switches" surface hopping algorithm of Tully was adapted to deal with the nonadiabaticity in trajectory propagations. The SECH model has been applied to study the DR of both CH+ and H3O+(H2O)2. The theoretical results are consistent with the experiment. It was found that water molecules play an important role in determining the product branching ratios of the molecular cluster ion.

LHC Report: Out of the clouds

CERN Multimedia

Giovanni Rumolo, Giovanni Iadarola and Hannes Bartosik for the LHC team

2015-01-01

In order for the LHC to deliver intense proton beams to the experiments, operators have to perform “scrubbing” of the beam pipes. This operation is necessary to reduce the formation of electron clouds, which would generate instabilities in the colliding beams.   Electron clouds are generated in accelerators running with positively charged particles when electrons - produced by the ionisation of residual molecules in the vacuum or by the photoelectric effect from synchrotron radiation - are accelerated by the beam field and hit the surface of the vacuum chamber producing other electrons. This avalanche-like process can result in the formation of clouds of electrons. Electron clouds are detrimental to the beam for a few reasons. First, the electrons impacting the walls desorb molecules and degrade the ultra-high vacuum in the beam chamber. Furthermore, they interact electromagnetically with the beam, leading to the oscillation and expansion of the particle bunches. This increases...

Self-Consistent 3D Modeling of Electron Cloud Dynamics and Beam Response

International Nuclear Information System (INIS)

Furman, Miguel; Furman, M.A.; Celata, C.M.; Kireeff-Covo, M.; Sonnad, K.G.; Vay, J.-L.; Venturini, M.; Cohen, R.; Friedman, A.; Grote, D.; Molvik, A.; Stoltz, P.

2007-01-01

We present recent advances in the modeling of beam electron-cloud dynamics, including surface effects such as secondary electron emission, gas desorption, etc, and volumetric effects such as ionization of residual gas and charge-exchange reactions. Simulations for the HCX facility with the code WARP/POSINST will be described and their validity demonstrated by benchmarks against measurements. The code models a wide range of physical processes and uses a number of novel techniques, including a large-timestep electron mover that smoothly interpolates between direct orbit calculation and guiding-center drift equations, and a new computational technique, based on a Lorentz transformation to a moving frame, that allows the cost of a fully 3D simulation to be reduced to that of a quasi-static approximation

Applications of electron beam to precoated steel

International Nuclear Information System (INIS)

Koshiishi, K.; Masuhara, K.

1992-01-01

Applications of EB to precoated steel started with paint cure and have expanded to film lamination and surface modification. These applications can offer precoated steel some advantages which are difficult or impossible to gain by thermal methods. But there are also such problems as adhesion, formability and paintability in EB processing. In practice, using EB technologies along with thermal technologies cannot be avoided for precoated steel at the present. Future development of EB applications to precoated steel will depend on how we can seek superiority and distinction of EB technology against conventional and competitive technologies. (author)

Gas Condensates onto a LHC Type Cryogenic Vacuum System Subjected to Electron Cloud

CERN Multimedia

Baglin, V

2004-01-01

In the Large Hadron Collider (LHC), the gas desorbed via photon stimulated molecular desorption or electron stimulated molecular desorption will be physisorbed onto the beam screen held between 5 and 20 K. Studies of the effects of the electron cloud onto a LHC type cryogenic vacuum chamber have been done with the cold bore experiment (COLDEX) installed in the CERN Super Proton Synchrotron (SPS). Experiments performed with gas condensates such as H2, H2O, CO and CO2 are described. Implications for the LHC design and operation are discussed.

Influence of Plastic Deformation of Steel Samples on the Fast electron Backscattering

International Nuclear Information System (INIS)

Sierra Trujillo, J. X.; Herrera Palma, V.; Desdin Garcia, L. F.; Codorniu Pujals, D.

2013-01-01

A considerable fraction of a fast electron beam incident on a target is scattered in backward direction. It is a very complex process involving electron - nucleus and electron - electron collisions. The fraction of backscattered electrons is described by a parameterization as a function of the atomic number and energy of the incident electrons. In such approaches the possible influence of the material structure is not taken into account. In this paper, the behavior of the 90 Sr/ 90 Y backscattered electrons from 08JuA and 15GJuT steel strained samples is investigated. A clear dependence between the degree of plastic deformation and the fraction of backscattered electrons was observed. This relationship is explained by the interaction of electrons with the dislocations in the material, whose density depends on the magnitude of the strain in the plastic region. On the basis of a simple model for describing this interaction, a mathematical expression is obtained for the relationship between the fraction of backscattered electrons and the degree of deformation. (Author)

Recent electron-cloud simulation results for the main damping rings of the NLC and TESLA linear colliders

International Nuclear Information System (INIS)

Pivi, M.; Raubenheimer, T.O.; Furman, M.A.

2003-01-01

In the beam pipe of the Main Damping Ring (MDR) of the Next Linear Collider (NLC), ionization of residual gases and secondary emission give rise to an electron-cloud which stabilizes to equilibrium after few bunch trains. In this paper, we present recent computer simulation results for the main features of the electron cloud at the NLC and preliminary simulation results for the TESLA main damping rings, obtained with the code POSINST that has been developed at LBNL, and lately in collaboration with SLAC, over the past 7 years. Possible remedies to mitigate the effect are also discussed. We have recently included the possibility to simulate different magnetic field configurations in our code including solenoid, quadrupole, sextupole and wiggler

Effect of beam oscillation on borated stainless steel electron beam welds

Energy Technology Data Exchange (ETDEWEB)

RajaKumar, Guttikonda [Tagore Engineering College, Chennai (India). Dept. of Mechanical Engineering; Ram, G.D. Janaki [Indian Institute of Technology (IIT), Chennai (India). Dept. of Metallurgical and Materials Engineering; Rao, S.R. Koteswara [SSN College of Engineering, Chennai (India). Mechanical Engineering

2015-07-01

Borated stainless steels are used in nuclear power plants to control neutron criticality in reactors as control rods, shielding material, spent fuel storage racks and transportation casks. In this study, bead on plate welds were made using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Electron beam welds made using beam oscillation technique exhibited higher tensile strength values compared to that of GTA welds. Electron beam welds were found to show fine dendritic microstructure while GTA welds exhibited larger dendrites. While both processes produced defect free welds, GTA welds are marked by partially melted zone (PMZ) where the hardness is low. EBW obviate the PMZ failure due to low heat input and in case of high heat input GTA welding process failure occurs in the PMZ.

Effect of beam oscillation on borated stainless steel electron beam welds

International Nuclear Information System (INIS)

RajaKumar, Guttikonda; Ram, G.D. Janaki; Rao, S.R. Koteswara

2015-01-01

Borated stainless steels are used in nuclear power plants to control neutron criticality in reactors as control rods, shielding material, spent fuel storage racks and transportation casks. In this study, bead on plate welds were made using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Electron beam welds made using beam oscillation technique exhibited higher tensile strength values compared to that of GTA welds. Electron beam welds were found to show fine dendritic microstructure while GTA welds exhibited larger dendrites. While both processes produced defect free welds, GTA welds are marked by partially melted zone (PMZ) where the hardness is low. EBW obviate the PMZ failure due to low heat input and in case of high heat input GTA welding process failure occurs in the PMZ.

Study of radiation-thermal effect of electron beam on steel and cast iron

International Nuclear Information System (INIS)

Machurin, E.S.; Lonchin, G.M.

1980-01-01

Studied is the influence of radiation-heat treatment by high energy (3-4.5 MeV) electron beam on the structure and properties of carbon steels (65G, 90KhF) and cast iron. Metallography and electron microscopy methods are used to study microstructure. It is shown that after the treatment by the electron beam there is observed noticeable structure grinding, sample fracture viscosity (even in a quenched state), increase of hardness and impact strength. The mechanism of metal heating process by electron beam is calculated and temperature field is defined in a heating region accounting for electron beam characteristics, medium and geometric factor. Theoretical data are close to experimental ones obtained in a course of determining the microhardness of irradiated samples for the cases of electron treatment duration up to 10 s

Study of the transport parameters of cloud lightning plasmas

International Nuclear Information System (INIS)

Chang, Z. S.; Yuan, P.; Zhao, N.

2010-01-01

Three spectra of cloud lightning have been acquired in Tibet (China) using a slitless grating spectrograph. The electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity of the cloud lightning, for the first time, are calculated by applying the transport theory of air plasma. In addition, we investigate the change behaviors of parameters (the temperature, the electron density, the electrical conductivity, the electron thermal conductivity, and the electron thermal diffusivity) in one of the cloud lightning channels. The result shows that these parameters decrease slightly along developing direction of the cloud lightning channel. Moreover, they represent similar sudden change behavior in tortuous positions and the branch of the cloud lightning channel.

Experimental project - Cloud chamber

International Nuclear Information System (INIS)

Nour, Elena; Quinchard, Gregory; Soudon, Paul

2015-01-01

This document reports an academic experimental project dealing with the general concepts of radioactivity and their application to the cloud room experiment. The author first recalls the history of the design and development of a cloud room, and some definitions and characteristics of cosmic radiation, and proposes a description of the principle and physics of a cloud room. The second part is a theoretical one, and addresses the involved particles, the origins of electrons, and issues related to the transfer of energy (Bremsstrahlung effect, Bragg peak). The third part reports the experimental work with the assessment of a cloud droplet radius, the identification of a trace for each particle (alphas and electrons), and the study of the magnetic field deviation

Protection of electronic health records (EHRs) in cloud.

Science.gov (United States)

Alabdulatif, Abdulatif; Khalil, Ibrahim; Mai, Vu

2013-01-01

EHR technology has come into widespread use and has attracted attention in healthcare institutions as well as in research. Cloud services are used to build efficient EHR systems and obtain the greatest benefits of EHR implementation. Many issues relating to building an ideal EHR system in the cloud, especially the tradeoff between flexibility and security, have recently surfaced. The privacy of patient records in cloud platforms is still a point of contention. In this research, we are going to improve the management of access control by restricting participants' access through the use of distinct encrypted parameters for each participant in the cloud-based database. Also, we implement and improve an existing secure index search algorithm to enhance the efficiency of information control and flow through a cloud-based EHR system. At the final stage, we contribute to the design of reliable, flexible and secure access control, enabling quick access to EHR information.

Void shrinkage in stainless steel during high energy electron irradiation

International Nuclear Information System (INIS)

Singh, B.N.; Foreman, A.J.E.

1976-03-01

During irradiation of thin foils of an austenitic stainless steel in a high voltage electron microscope, steadily growing voids have been observed to suddenly shrink and disappear at the irradiation temperature of 650 0 Cthe phenomenon has been observed in specimens both with and withoutimplanted helium. Possible mechanisms for void shrinkage during irradiation are considered. It is suggested that the dislocation-pipe-diffusion of vacancies from or of self-interstitial atoms to the voids can explain the shrinkage behaviour of voids observed during our experiments. (author)

The electron-cloud instability in PEP-II: An update

International Nuclear Information System (INIS)

Furman, M.A.; Lambertson, G.R.

1997-05-01

The authors present an update on the estimate of the growth time of the multi-bunch transverse instability in the PEP-II collider arising from the interaction of the positron beam with the accumulated electron cloud. They estimate the contributions to the growth rate arising from the dipole magnets and from the pumping straight sections. They emphasize those quantities upon which the instability is most sensitive. The simulation includes measured data on the secondary emission yield for TiN-coated samples of the actual vacuum chamber. Although the analysis is still in progress, they conclude that the instability risetime is of order 1 ms, which is well within the range controllable by the feedback system

Understanding the Effect of Ni on Mechanical and Wear Properties of Low-Carbon Steel from a View-Point of Electron Work Function

Science.gov (United States)

Lu, Hao; Huang, Xiaochen; Hou, Runfang; Li, D. Y.

2018-04-01

Electron work function (EWF) is correlated to intrinsic properties of metallic materials and can be an alternative parameter to obtain supplementary clues for guiding material design and modification. A higher EWF corresponds to a more stable electronic state, leading to higher resistance to any attempt to change the material structure and properties. In this study, effects of Ni as a solute with a higher EWF on mechanical, electrochemical, and tribological properties of low-carbon steel were investigated. Added Ni, which has more valence electrons, enhanced the electrons-nuclei interaction in the steel, corresponding to higher EWF. As a result, the Ni-added steel showed increased mechanical strength and corrosion resistance, resulting in higher resistances to wear and corrosive wear. Mechanism for the improvements is elucidated through analyzing EWF-related variations in Young's modulus, hardness, corrosion potential, and tribological behavior.

Characterization of atom clusters in irradiated pressure vessel steels and model alloys

International Nuclear Information System (INIS)

Auger, P.; Pareige, P.; Akamatsu, M.; Van Duysen, J.C.

1993-12-01

In order to characterize the microstructural evolution of the iron solid solution under irradiation, two pressure vessel steels irradiated in service conditions and, for comparison, low copper model alloys irradiated with neutrons and electrons have been studied. The characterization has been carried out mainly thanks to small angle neutron scattering and atom probe experiments. Both techniques lead to the conclusion that clusters develop with irradiations. In Fe-Cu model alloys, copper clusters are formed containing uncertain proportions of iron. In the low copper industrial steels, the feature is more complex. Solute atoms like Ni, Mn and Si, sometimes associated with Cu, segregate as ''clouds'' more or less condensed in the iron solid solution. These silicides, or at least Si, Ni, Mn association, may facilitate the copper segregation although the initial iron matrix contains a low copper concentration. (authors). 24 refs., 3 figs., 2 tabs

Effect of the Electron Cloud and CSR on the Upgrade of the PEP-II

International Nuclear Information System (INIS)

Heifets, Samuel A

2001-01-01

Effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the possible upgrade of the PEP-II B-factory are studied. PEP-II B factory operates with parameters shown in Table 1 and already exceeds the design luminosity. Nevertheless, a possibility of upgrading the machine to even higher luminosities is under consideration [1]. Several scenarios are summarized in Table 2. This paper describes effects of the electron cloud and of the coherent synchrotron radiation (CSR) on the proposed upgrades of the PEP-II B-factory. The first effect was observed [3] and caused [4] the degradation of the emittance at KEK B-factory. The analytic expression for the e-wake [2] is used in calculations of the head-tail instability. Other obvious effects of higher beam currents such as additional heat load are not considered. The short wave length CSR has been recently observed at Brookhaven [6]. Consideration of the effect of such CSR on the beam dynamics is based on our previous paper [7

Electron cloud density analysis using microwave cavity resonance

International Nuclear Information System (INIS)

Shin, Y-M; Thangaraj, J C; Tan, C-Y; Zwaska, R

2013-01-01

We report on a method to detect an electron cloud in proton accelerators through the measurement of the phase shift of microwaves undergoing controlled reflections with an accelerator vacuum vessel. Previous phase shift measurement suffered from interference signals due to uncontrolled reflections from beamline components, leading to an unlocalized region of measurement and indeterminate normalization. The method in this paper introduces controlled reflectors about the area of interest to localize the measurement and allow normalization. This paper describes analyses of the method via theoretical calculations, electromagnetic modeling, and experimental measurements with a bench-top prototype. Dielectric thickness, location and spatial profile were varied and the effect on phase shift is described. The effect of end cap aperture length on phase shift measurement is also reported. A factor of ten enhancement in phase shift is observed at certain frequencies.

Automatic atlas based electron density and structure contouring for MRI-based prostate radiation therapy on the cloud

International Nuclear Information System (INIS)

Dowling, J A; Burdett, N; Chandra, S; Rivest-Hénault, D; Ghose, S; Salvado, O; Fripp, J; Greer, P B; Sun, J; Parker, J; Pichler, P; Stanwell, P

2014-01-01

Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans.

Automatic Atlas Based Electron Density and Structure Contouring for MRI-based Prostate Radiation Therapy on the Cloud

Science.gov (United States)

Dowling, J. A.; Burdett, N.; Greer, P. B.; Sun, J.; Parker, J.; Pichler, P.; Stanwell, P.; Chandra, S.; Rivest-Hénault, D.; Ghose, S.; Salvado, O.; Fripp, J.

2014-03-01

Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans.

Theoretical Studies of TE-Wave Propagation as a Diagnostic for Electron Cloud

International Nuclear Information System (INIS)

Penn, Gregory E.; Vay, Jean-Luc

2010-01-01

The propagation of TE waves is sensitive to the presence of an electron cloud primarily through phase shifts generated by the altered dielectric function, but can also lead to polarization changes and other effects, especially in the presence of magnetic fields. These effects are studied theoretically and also through simulations using WARP. Examples are shown related to CesrTA parameters, and used to observe different regimes of operation as well as to validate estimates of the phase shift.

Identify and rank key factors influencing the adoption of cloud computing for a healthy Electronics

Directory of Open Access Journals (Sweden)

Javad Shukuhy

2015-02-01

Full Text Available Cloud computing as a new technology with Internet infrastructure and new approaches can be significant benefits in providing medical services electronically. Aplying this technology in E-Health requires consideration of various factors. The main objective of this study is to identify and rank the factors influencing the adoption of e-health cloud. Based on the Technology-Organization-Environment (TOE framework and Human-Organization-Technology fit (HOT-fit model, 16 sub-factors were identified in four major factors. With survey of 60 experts, academics and experts in health information technology and with the help of fuzzy analytic hierarchy process had ranked these sub-factors and factors. In the literature, considering newness this study, no internal or external study, have not alluded these number of criteria. The results show that when deciding to adopt cloud computing in E-Health, respectively, must be considered technological, human, organizational and environmental factors.

Comparison of electron cloud simulation and experiments in the high-current experiment

International Nuclear Information System (INIS)

Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Verboncoeur, J.; Stoltz, P.; Veitzer, S.

2004-01-01

A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability

A cloud-based production system for information and service integration: an internet of things case study on waste electronics

Science.gov (United States)

Wang, Xi Vincent; Wang, Lihui

2017-08-01

Cloud computing is the new enabling technology that offers centralised computing, flexible data storage and scalable services. In the manufacturing context, it is possible to utilise the Cloud technology to integrate and provide industrial resources and capabilities in terms of Cloud services. In this paper, a function block-based integration mechanism is developed to connect various types of production resources. A Cloud-based architecture is also deployed to offer a service pool which maintains these resources as production services. The proposed system provides a flexible and integrated information environment for the Cloud-based production system. As a specific type of manufacturing, Waste Electrical and Electronic Equipment (WEEE) remanufacturing experiences difficulties in system integration, information exchange and resource management. In this research, WEEE is selected as the example of Internet of Things to demonstrate how the obstacles and bottlenecks are overcome with the help of Cloud-based informatics approach. In the case studies, the WEEE recycle/recovery capabilities are also integrated and deployed as flexible Cloud services. Supporting mechanisms and technologies are presented and evaluated towards the end of the paper.

Cloud services in organization

OpenAIRE

FUXA, Jan

2013-01-01

The work deals with the definition of the word cloud computing, cloud computing models, types, advantages, disadvantages, and comparing SaaS solutions such as: Google Apps and Office 365 in the area of electronic communications. The work deals with the use of cloud computing in the corporate practice, both good and bad practice. The following section describes the methodology for choosing the appropriate cloud service organization. Another part deals with analyzing the possibilities of SaaS i...

Low Secondary Electron Yield Carbon Coatings for Electron-cloud Mitigation in Modern Particle Accelerators

CERN Document Server

Yin Vallgren, Christina; Calatroni, Sergio; Chiggiato, Paolo; Costa Pinto, Pedro; Marques, Hugo; Neupert, Holger; Taborelli, Mauro; Vollenberg, Wilhelmus; Wevers, Ivo; Yaqub, Kashif

2010-01-01

Electron-cloud is one of the main limitations for particle accelerators with positively charged beams of high intensity and short bunch spacing, as the SPS at CERN. The Secondary Electron Yield (SEY) of the inner surface of the vacuum chamber is the main parameter governing the phenomenon. The effect could be eliminated by coating the vacuum chambers with a material of low SEY, which does not require bake-out and is robust against air exposure. For such a purpose amorphous carbon (a-C) coatings were produced by magnetron sputtering of graphite targets. They exhibit maximum SEY between 0.95 and 1.05 after air transfer to the measuring instrument. After 1 month of air exposure the SEY rises by 10 - 20 % of the initial values. Storage in desiccator or by packaging in Al foil makes this increase negligible. The coatings have a similar X-ray photoelectron spectroscopy (XPS) C1s spectrum for a large set of deposition parameters and exhibit an enlarged linewidth compared to HOPG graphite. The static outgassing witho...

The Electron-Cloud Effect in the Arcs of the LHC

CERN Document Server

Furman, M A

1998-01-01

We present an update of our estimates for the power deposition arising from the electron-cloud effect in the dipole bending magnets in the arcs of the LHC. In addition, we present the estimate of the power deposition in the field-free regions in the arcs. We hold the number of particles per bunch and the bunch spacing fixed at their nominal values, and we assume throughout a high photon reflectivi ty. We explore the dependence of the power deposition on the photoelectric efficiency and on secondary emission yield parameters. We find a marked sensitivity to parameters that characterize secondary emission on the scale of 5 - 10 eV.

Electron cloud measurements in heavy-ion driver for HEDP and inertial fusion energy

International Nuclear Information System (INIS)

Kireeff Covo, Michel; Molvik, Arthur W.; Friedman, Alex; Cohen, Ronald; Vay, Jean-Luc; Bieniosek, Frank; Baca, David; Seidl, Peter A.; Logan, Grant; Vujic, Jasmina L.

2007-01-01

The high-current experiment (HCX) at LBNL is a driver scale single beam injector that provides a 1 MeV K + ion beam current of 0.18 A for 5 μs. It transports high-current beams with large fill factor (ratio of the maximum beam envelope radius to the beam pipe radius) and low emittance growth that are required to keep the cost of the power plant competitive and to satisfy the target requirements of focusing ion beams to high-power density. Beam interaction with the background gas and walls desorbs electrons that can multiply and accumulate, creating an electron cloud. This ubiquitous effect grows at higher fill factors and degrades the quality of the beam. We review simulations and diagnostics tools used to measure electron production, accumulation and its properties

Microbial-Influenced Corrosion of Corten Steel Compared with Carbon Steel and Stainless Steel in Oily Wastewater by Pseudomonas aeruginosa

Science.gov (United States)

Mansouri, Hamidreza; Alavi, Seyed Abolhasan; Fotovat, Meysam

2015-07-01

The microbial corrosion behavior of three important steels (carbon steel, stainless steel, and Corten steel) was investigated in semi petroleum medium. This work was done in modified nutrient broth (2 g nutrient broth in 1 L oily wastewater) in the presence of Pseudomonas aeruginosa and mixed culture (as a biotic media) and an abiotic medium for 2 weeks. The behavior of corrosion was analyzed by spectrophotometric and electrochemical methods and at the end was confirmed by scanning electron microscopy. The results show that the degree of corrosion of Corten steel in mixed culture, unlike carbon steel and stainless steel, is less than P. aeruginosa inoculated medium because some bacteria affect Corten steel less than other steels. According to the experiments, carbon steel had less resistance than Corten steel and stainless steel. Furthermore, biofilm inhibits separated particles of those steels to spread to the medium; in other words, particles get trapped between biofilm and steel.

Study of glow discharge positive column with cloud of disperse particles

International Nuclear Information System (INIS)

Polyakov, D.N.; Shumova, V.V.; Vasilyak, L.M.; Fortov, V.E.

2011-01-01

The study aims to describe plasma parameters changes induced by clouds of disperse micron size particles. Dust clouds were formed in the positive column of glow discharge in air at pressure 0.1-0.6 torr and current 0.1-3 mA. The simultaneous registration of discharge voltage and dust cloud parameters was carried out. Experimental results were simulated using diffusion model. The dust cloud is shown to smooth the radial electron concentration profile, increase electric field strength and electron temperature and stabilize the discharge. The cloud is demonstrated to be a trap for positive ions without increase of discharge current. -- Highlights: → 25% increase of longitudinal electric field strength in discharge with dust cloud. → The smoothing effect of dust cloud on radial electron and ion concentration profiles. → Dust cloud as a trap for positive ions without increase of discharge current. → Increase of electron temperature in discharge with dust cloud. → Increase of discharge stability in presence of dust cloud.

A New Chicane Experiment In PEP-II to Test Mitigations of the Electron Cloud Effect for Linear Colliders

International Nuclear Information System (INIS)

Pivi, M

2008-01-01

Beam instability caused by the electron cloud has been observed in positron and proton storage rings, and it is expected to be a limiting factor in the performance of future colliders [1-3]. The effect is expected to be particularly severe in magnetic field regions. To test possible mitigation methods in magnetic fields, we have installed a new 4-dipole chicane experiment in the PEP-II Low Energy Ring (LER) at SLAC with both bare and TiN-coated aluminum chambers. In particular, we have observed a large variation of the electron flux at the chamber wall as a function of the chicane dipole field. We infer this is a new high order resonance effect where the energy gained by the electrons in the positron beam depends on the phase of the electron cyclotron motion with respect to the bunch crossing, leading to a modulation of the secondary electron production. Presumably the cloud density is modulated as well and this resonance effect could be used to reduce its magnitude in future colliders. We present the experimental results obtained during January 2008 until the April final shut-down of the PEP-II machine

Electron cloud in the CERN accelerator complex

CERN Document Server

AUTHOR|(CDS)2069325; Bartosik, Hannes; Belli, Eleonora; Iadarola, Giovanni; Li, Kevin Shing Bruce; Mether, Lotta Maria; Romano, Annalisa; Schenk, Michael

2016-01-01

Operation with closely spaced bunched beams causes the build-up of an Electron Cloud (EC) in both the LHC and the two last synchrotrons of its injector chain (PS and SPS). Pressure rise and beam instabilities are observed at the PS during the last stage of preparation of the LHC beams. The SPS was affected by coherent and incoherent emittance growth along the LHC bunch train over many years, before scrubbing has finally suppressed the EC in a large fraction of the machine. When the LHC started regular operation with 50 ns beams in 2011, EC phenomena appeared in the arcs during the early phases, and in the interaction regions with two beams all along the run. Operation with 25 ns beams (late 2012 and 2015), which is nominal for LHC, has been hampered by EC induced high heat load in the cold arcs, bunch dependent emittance growth and degraded beam lifetime. Dedicated and parasitic machine scrubbing is presently the weapon used at the LHC to combat EC in this mode of operation. This talk summarises the EC experi...

Electron cloud simulation of the ECR plasma

International Nuclear Information System (INIS)

Racz, R.; Biri, S.; Palinkas, J.

2011-01-01

Complete text of publication follows. The plasma of the Electron Cyclotron Resonance Ion Source (ECRIS) of ATOMKI is being continuously investigated by different diagnostic methods: using small-sized probes or taking X-ray and visible light photographs. In 2011 three articles were published by our team in a special edition of the IEEE Transactions on Plasma Science (Special Issue on Images in Plasma Science) describing our X-ray and visible light measurements and plasma modeling and simulating studies. Simulation is in many cases the base for the analysis of the photographs. The outcomes of the X-ray and visible light experiments were presented already in earlier issues of the Atomki Annual Report, therefore in this year we concentrate on the results of the simulating studies. The spatial distribution of the three main electron components (cold, warm and hot electron clouds) of the ECR plasmas was simulated by TrapCAD code. TrapCAD is a 'limited' plasma simulation code. The spatial and energy evolution of a large number of electrons can be realistically followed; however, these particles are independent, and no particle interactions are included. In ECRISs, the magnetic trap confines the electrons which keep together the ion component by their space charge. The electrons gain high energies while the ions remain very cold throughout the whole process. Thus, the spatial and energy simulation of the electron component gives much important and numerical information even for the ions. The electron components of ECRISs can artificially be grouped into three populations: cold, warm, and hot electrons. Cold electrons (1-200 eV) have not been heated by the microwave; they are mainly responsible for the visible light emission of the plasma. The energized warm electrons (several kiloelectronvolts) are able to ionize atoms and ions and they are mainly responsible for the characteristic Xray photons emitted by the plasma. Electrons having much higher energy than necessary for

Experimental study of collective acceleration of light and heavy ions from a localized gas cloud

International Nuclear Information System (INIS)

Floyd, L.E. IV.

1984-01-01

An experimental investigation into the collective acceleration of various gaseous atoms (H, D, He, N, Ne, Ar, Kr, Xe) is presented. A localized gas cloud is formed using a fast rise puff valve immediately downstream of an intense relativistic electron beam diode. The diode consists of a tungsten needle cathode and a stainless steel anode with a hole on axis. The diode is driven by an electron beam generator system consisting of a Marx generator, Blumlein line, and transmission line transformer. It produces a 1.5 MV, 35 kA, 30 ns FWHM electrical pulse measured at the diode. The resulting electron beam has nu/γ approx. 1 and is about six times the vacuum space charge limiting current in the downstream drift chamber. Ions are produced during the impact of the electron beam with the gas cloud and are accelerated to high energy by collective effects associated with the electron beam space charge. Ion energy diagnostics include fast neutron counting, nuclear activation of stacked foils, measurement of time of flight using direct intercept current collector probes, and range/energy analysis of nuclear track plates. The principal result of the experiments was that all ion species were accelerated to a maximum velocity of 0.1c, corresponding to an energy of 4.7 MeV/nucleon. Energy spectra obtained from stacked foil activation for accelerated hydrogen and deuterium were found to be approximately exponential in character

Corrosion of mild steel and stainless steel by marine Vibrio sp.

Digital Repository Service at National Institute of Oceanography (India)

PrabhaDevi; Wagh, A.B.

Microbially induced corrosion (MIC) of stainless steel and mild steel coupons exposed to media with and without a bacterial culture Vibrio sp. was studied using Scanning Electron Microscope (SEM). Pitting type of corrosion was noticed which was more...

Hardening and microstructural evolution of A533b steels irradiated with Fe ions and electrons

Energy Technology Data Exchange (ETDEWEB)

Watanabe, H., E-mail: watanabe@riam.kyushu-u.ac.jp [Research Institute for Applied Mechanics, Kyushu University, 6-1, Kasuga-kouenn, Kasugashi, Fukuoka, 816-8580 (Japan); Arase, S. [Interdisciplinary Graduate School of Kyushu University, 6-1, Kasuga-kouenn, Kasugashi, Fukuoka, 816-8580 (Japan); Yamamoto, T.; Wells, P. [Dept. Chemical Engineering, UCSB Engineering II, RM3357, Santa Barbara, CA, 93106-5080 (United States); Onishi, T. [Interdisciplinary Graduate School of Kyushu University, 6-1, Kasuga-kouenn, Kasugashi, Fukuoka, 816-8580 (Japan); Odette, G.R. [Dept. Chemical Engineering, UCSB Engineering II, RM3357, Santa Barbara, CA, 93106-5080 (United States)

2016-04-01

Radiation hardening and embrittlement of A533B steels is heavily dependent on the Cu content. In this study, to investigate the effect of copper on the microstructural evolution of these materials, A533B steels with different Cu levels were irradiated with 2.4 MeV Fe ions and 1.0 MeV electrons. Ion irradiation was performed from room temperature (RT) to 350 °C with doses up to 1 dpa. At RT and 290 °C, low dose (<0.1 dpa) hardening trend corresponded with ΔH ∝ (dpa){sup n}, with n initially approximately 0.5 and consistent with a barrier hardening mechanism, but saturating at ≈0.1 dpa. At higher dose levels, the radiation-induced hardening exhibited a strong Cu content dependence at 290 °C, but not at 350 °C. Electron irradiation using high-voltage electron microscopy revealed the growth of interstitial-type dislocation loops and enrichment of Ni, Mn, and Si in the vicinities of pre-existing dislocations at doses for which the radiation-induced hardness due to ion irradiation was prominent.

Conversion electron Moessbauer and XPS study on the effect of polishing of a stainless steel sample

International Nuclear Information System (INIS)

Vertes, Cs.; Kuzmann, E.; Lakatos-Varsanyi, M.; Vertes, A.; Vass, G.; Romhanyi, K.

1994-01-01

Conversion electron Moessbauer spectroscopy (CEMS) and XPS has been used for the surface analysis of an 'X10CrNiTi 18/9 (DIN 1.7440)'-type stainless steel in order to determine the supposed structural and/or chemical changes in the surface layer caused by polishing. Both, CEMS and XPS results can be associated with the appearance of Fe nitride in the outer layer of steel samples after polishing, while no sing of nitrogen was detected in the bulk material. (author) 9 refs.; 3 figs.; 1 tab

Ductile fracture of two-phase welds under 77K. [Steel-EhP810, steel-EhP666, steel-08Kh18N10T, steel-EhP659-VI, steel-chP810

Energy Technology Data Exchange (ETDEWEB)

Yushchenko, K.A.; Voronin, S.A.; Pustovit, A.I.; Shavel' , A.V.

The effect of the type of welding and fillers on crack resistance of welded joints high-strength steel EhP810 and its various compounds with steels EhP666, 08Kh18N10T has been studied. For the welding of steel EhP810 with steels EhP810, EhP666, 08Kh18N10T electron-beam, automatic, argon tungsten arc with non-consumable electrode with various fillers, as well as argon metal-arc welding with consumable electrode, were used. It is shown, that for a joint, made by electron-beam welding, parameters sigmasub(u), Ksub(IcJ), KCV are higher than for a joint of a similar phase structure made using filler wire EhP659-VI. It is explained by the fact, that during electron-beam welding joint metal refining takes place, which removes gases. In welded joints of chP810 steel, having joints with austenitic structure, characteristic of crack resistance Ssub(c) increases by more than 0.2 mm in contrast to two-phase joints, which conventional yield strength at 77 K exceeds 1000 MPa. It is worth mentioning, that for other classes of steels formation of two-phase structure of joint increases welded joint resistance to brittle fracture. It is possible to obtain the required structure of joint with assigned level of resistance to brittle fracture by means of the use of different fillers, optimum and welding procedure, regulating the part of the basic metal in joint content.

Chemical state analysis of oxidation products on steel surface by conversion electron Moessbauer spectrometry

International Nuclear Information System (INIS)

Ujihira, Yusuke; Nomura, Kiyoshi

1978-01-01

The polished NT-70H steel (Fe: 95.97%, C: 0.56%, diameter: 5 cm, thickness: 0.5 cm) was immersed in deionized water or in solutions containing (0.25 -- 0.5) M of chloride, sulfate and nitrate ions. The chemical states of oxidation products of iron on the surface were identified through the analysis of conversion electron Moessbauer spectra (CEMS). CEMS of the steel surface, which had been dipped in deionized water, revealed that γ-FeOOH was formed on the surface. The thickness of γ-FeOOH layer increased with the increase of the duration of dipping. Dissolved oxygen in the solution played an essential role in the oxidation of iron to γ-FeOOH. Oxidation product of iron dipped in the 0.5 M sodium chloride solution was identified as γ-FeOOH. Amorphous paramagnetic iron (III) compound tended to form in the presence of hydrogen peroxide or ammonium ions in the solutions. The increase of alkalinity of the solution up to pH 12 suppressed the oxidation rate and assisted the formation of green rust, which was confirmed by the appearance of the quadrupole splitting peaks of the green rust. In the 0.25 M sodium sulfate solution, oxidation of the steel surface proceeded slowly and the quadrupole splitting peaks of Fe(OH) 2 were seen in the CEMS. The peak intensity of Fe(OH) 2 gradually decreased and that of γ-FeOOH increased by the extension of immersion of steel in the solution. Magnetite (Fe 3 O 4 ) layer was developed beneath the γ-FeOOH layer, when steel was dipped in 0.5 M sodium nitrate solution. However, the peaks of Fe 3 O 4 were not seen on CEMS of steel surface immersed in 0.5 M ammonium nitrate solution. Thus, applying the feasibility of CEMS for the characterization of oxidated compounds of iron on the steel surface formed by the immersion in solutions, the oxidation mechanism of the steel surface was discussed based upon the results of chemical state analyses. (author)

Improving electron beam weldability of heavy steel plates for PWR-steam generator

International Nuclear Information System (INIS)

Tomita, Yukio; Mabuchi, Hidesato; Koyama, Kunio

1996-01-01

Installation and replacement of many PWR-steam generators are planned inside and outside Japan. The steel plates for steam generators are heavy in thickness, and increase the number of welding passes and prolong the welding time. Electron beam welding (EBW) can greatly reduce the welding period compared with conventional welding methods (narrow-gap gas metal arc welding (GMAW) and submerged arc welding (SAW)). The problems in applying EBW are to prevent weld defects and to improve the toughness of the weld metal. Defect-free welding procedures were successfully established even in thick steel plates. The factors that deteriorate weld-metal (WM) toughness of EBW were investigated. The manufacturing process, which utilizes a new secondary refining process at steelmaking and a high-torque mill at plate mill in actual mass-production, were established. EBW base metal and WM have better properties including fracture toughness than those of conventional welding processes. As a result, an application of EBW to the fabrication of PWR-steam generators has become possible. Large amounts of ASTM A533 Gr B Cl 2 (JIS SQV2B) steel plates in actual PWR-steam generators have come to be produced (more than 1,500 ton) by applying EBW. (author)

LHC Report: out of the clouds (part II)

CERN Multimedia

Giovanni Rumolo for the LHC team

2015-01-01

A large fraction of the LHC beam-time over the last two weeks has been devoted to the second phase of the scrubbing of the vacuum chambers. This was aimed at reducing the formation of electron clouds in the beam pipes, this time performed with 25-nanosecond spaced bunches. This operation is designed to prepare the machine for a smooth intensity ramp-up for physics with this type of beam.   The scrubbing of the accelerator beam pipes is done by running the machine under an intense electron cloud regime while respecting beam stability constraints. When electron cloud production becomes sufficiently intense, the probability of creating secondary electrons at the chamber walls decreases and this inhibits the whole process. In this way, the scrubbing operation eventually reduces the formation of electron clouds, which would otherwise generate instabilities in the colliding beams. The second phase of LHC scrubbing started on Saturday, 25 July, when 25 ns beams were circulated again in the LHC...

Recent Experimental Results on Amorphous Carbon Coatings for Electron Cloud Mitigation

CERN Document Server

Yin Vallgren, C; Chiggiato, P; Costa Pinto, P; Neupert, H; Taborelli, M; Rumolo, G; Shaposhnikova, E; Vollenberg, W

2011-01-01

Amorphous carbon (a-C) thin films, produced in different coating configurations by using DC magnetron sputtering, have been investigated in laboratory for low secondary electron yield (SEY) applications. After the coatings had shown a reliable low initial SEY, the a-C thin films have been applied in the CERN Super Proton Synchrotron (SPS) and tested with Large Hadron Collider (LHC) type beams.Currently, we have used a-C thin film coated in so-called liner configuration for the electron cloud monitors. In addition the vacuum chambers of three dipole magnets have been coated and inserted into the machine. After describing the different configurations used for the coatings, results of the tests in the machine and a summary of the analyses after extraction will be presented. Based on comparison between different coating configurations, a new series of coatings has been applied on three further dipole magnet vacuum chambers. They have been installed and will be tested in coming machine development runs.

TU-F-CAMPUS-T-05: A Cloud-Based Monte Carlo Dose Calculation for Electron Cutout Factors

Energy Technology Data Exchange (ETDEWEB)

Mitchell, T; Bush, K [Stanford School of Medicine, Stanford, CA (United States)

2015-06-15

Purpose: For electron cutouts of smaller sizes, it is necessary to verify electron cutout factors due to perturbations in electron scattering. Often, this requires a physical measurement using a small ion chamber, diode, or film. The purpose of this study is to develop a fast Monte Carlo based dose calculation framework that requires only a smart phone photograph of the cutout and specification of the SSD and energy to determine the electron cutout factor, with the ultimate goal of making this cloud-based calculation widely available to the medical physics community. Methods: The algorithm uses a pattern recognition technique to identify the corners of the cutout in the photograph as shown in Figure 1. It then corrects for variations in perspective, scaling, and translation of the photograph introduced by the user’s positioning of the camera. Blob detection is used to identify the portions of the cutout which comprise the aperture and the portions which are cutout material. This information is then used define physical densities of the voxels used in the Monte Carlo dose calculation algorithm as shown in Figure 2, and select a particle source from a pre-computed library of phase-spaces scored above the cutout. The electron cutout factor is obtained by taking a ratio of the maximum dose delivered with the cutout in place to the dose delivered under calibration/reference conditions. Results: The algorithm has been shown to successfully identify all necessary features of the electron cutout to perform the calculation. Subsequent testing will be performed to compare the Monte Carlo results with a physical measurement. Conclusion: A simple, cloud-based method of calculating electron cutout factors could eliminate the need for physical measurements and substantially reduce the time required to properly assure accurate dose delivery.

Improvement in the cloud mask for Terra MODIS mitigated by electronic crosstalk correction in the 6.7 μm and 8.5 μm channels

Science.gov (United States)

Sun, Junqiang; Madhavan, S.; Wang, M.

2016-09-01

MODerate resolution Imaging Spectroradiometer (MODIS), a remarkable heritage sensor in the fleet of Earth Observing System for the National Aeronautics and Space Administration (NASA) is in space orbit on two spacecrafts. They are the Terra (T) and Aqua (A) platforms which tracks the Earth in the morning and afternoon orbits. T-MODIS has continued to operate over 15 years easily surpassing the 6 year design life time on orbit. Of the several science products derived from MODIS, one of the primary derivatives is the MODIS Cloud Mask (MOD035). The cloud mask algorithm incorporates several of the MODIS channels in both reflective and thermal infrared wavelengths to identify cloud pixels from clear sky. Two of the thermal infrared channels used in detecting clouds are the 6.7 μm and 8.5 μm. Based on a difference threshold with the 11 μm channel, the 6.7 μm channel helps in identifying thick high clouds while the 8.5 μm channel being useful for identifying thin clouds. Starting 2010, it had been observed in the cloud mask products that several pixels have been misclassified due to the change in the thermal band radiometry. The long-term radiometric changes in these thermal channels have been attributed to the electronic crosstalk contamination. In this paper, the improvement in cloud detection using the 6.7 μm and 8.5 μm channels are demonstrated using the electronic crosstalk correction. The electronic crosstalk phenomena analysis and characterization were developed using the regular moon observation of MODIS and reported in several works. The results presented in this paper should significantly help in improving the MOD035 product, maintaining the long term dataset from T-MODIS which is important for global change monitoring.

Electron-cloud simulation studies for the CERN-PS in the framework of the LHC Injectors Upgrade project

CERN Document Server

Rioja Fuentelsaz, Sergio

The present study aims to provide a consistent picture of the electron cloud effect in the CERN Proton Synchrotron (PS) and to investigate possible future limitations due to the requirements foreseen by the LHC Injectors Upgrade (LIU) project. It consists of a complete simulation survey of the electron cloud build-up in the different beam pipe sections of the ring depending on several controllable beam parameters and vacuum chamber surface properties, covering present and future operation parameters. As the combined function magnets of the accelerator constitute almost the $80\\%$ in length of the ring, the implementation of a new feature for the simulation of any external magnetic field on the PyECLOUD code, made it possible to perform this study. All the results of the simulations are given as a function of the vacuum chamber surface properties in order to deduce them, both locally and globally, when compared with experimental data. In a first step, we characterize locally the maximum possible number of ...

Application of ab initio electronic structure calculations for prediction of phase equilibria in superaustenitic steels

Czech Academy of Sciences Publication Activity Database

Vřešťál, J.; Kroupa, Aleš; Šob, Mojmír

2006-01-01

Roč. 38, č. 11 (2006), s. 298-302 ISSN 0927-0256 R&D Projects: GA ČR(CZ) GA106/03/1354; GA AV ČR(CZ) IBS2041105 Institutional research plan: CEZ:AV0Z20410507 Keywords : electronic structure * Phase diagrams * Steel Subject RIV: BJ - Thermodynamics Impact factor: 1.104, year: 2006

Cloud chamber photographs of the cosmic radiation

CERN Document Server

Rochester, George Dixon

1952-01-01

Cloud Chamber Photographs of the Cosmic Radiation focuses on cloud chamber and photographic emulsion wherein the tracks of individual subatomic particles of high energy are studied. The publication first offers information on the technical features of operation and electrons and cascade showers. Discussions focus on the relationship in time and space of counter-controlled tracks; techniques of internal control of the cloud chamber; cascade processes with artificially-produced electrons and photons; and nuclear interaction associated with an extensive shower. The manuscript then elaborates on

A stability analysis of electron-positron pair equilibria of a two-temperature plasma cloud

Energy Technology Data Exchange (ETDEWEB)

Sikora, M [Colorado Univ., Boulder, CO (USA); Zbyszewska, M [Polska Akademia Nauk, Warsaw (Poland). Centrum Astronomiczne

1986-01-01

The stability of a two-temperature homogeneous static plasma cloud against pair density perturbations is examined. We assumed that the electrons and positrons, cooled via radiation process, are reheated via Coulomb interactions with much hotter protons. Pair equilibrium plasma states are shown to be unstable if deltan{sub e}/deltan{sub p}<0 and deltan{sub e}/deltaT{sub p}<0 on the equilibrium surface n{sub e}{sup eq}(n{sub p},T{sub p}), where n{sub e}=n{sub +}+n{sub -}, n{sub p} and T{sub p} denote electron plus positron density, proton density and proton temperature, respectively. The minimum proton temperature and maximum proton density for which unstable states can appear are: (kT{sub p}){sub min} approx few x m{sub e}c{sup 2} and (n{sub p}){sub max} approx few/Rsigma{sub T}, where R is the plasma cloud radius. We discuss our results in the context of an accreting black hole model assuming that the proton temperature is close to its virial value, kT{sub p}{sup vir} approx GMm{sub p}/R and that subsonic accretion flow is realized at R < tens Schwarzschild radii. The unstable states then correspond to the luminosity range 0.01 L{sub Edd}electron temperature range 2 x 10{sup 9}K

Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

International Nuclear Information System (INIS)

Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Wu, Jennifer W.

2008-01-01

Computer simulations using the 2D code 'POSINST' were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was less than approximately 0.6 T, equilibrium average electron densities were up to three times the density found at other neighboring field values. Effects of this resonance between the bunch and cyclotron frequency are expected to be non-negligible when the beam bunch length is much less than the product of the electron cyclotron period and the beam

Void swelling behaviour of austenitic stainless steel during electron irradiation

International Nuclear Information System (INIS)

Sheng Zhongqi; Xiao Hong; Peng Feng; Ti Zhongxin

1994-04-01

The irradiation swelling behaviour of 00Cr17Ni14Mo2 austenitic stainless steel (AISI 316L) was investigated by means of high voltage electron microscope. Results showed that in solution annealed condition almost no swelling incubation period existed, and the swelling shifted from the transition period to the steady-state one when the displacement damage was around 40 dpa. In cold rolled condition there was evidently incubation period, and when the displacement damage was up to 84 dpa the swelling still remained in the transition period. The average size and density of voids in both conditions were measured, and the factors, which influenced the void swelling, were discussed. (3 figs.)

Electron microscopy and plastic deformation of industrial austenitic stainless steels

International Nuclear Information System (INIS)

Thomas, Barry

1976-01-01

The different mechanisms of plastic deformation observed in austenitic stainless steels are described and the role of transmission electron microscopy in the elucidation of the mechanisms is presented. At temperatures below 0,5Tm, different variants of dislocation glide are competitive: slip of perfect and partial dislocations, mechanical twinning and strain-induced phase transformations. The predominance of one or other of these mechanisms can be rationalized in terms of the temperature and composition dependence of the stacking fault energy and the thermodynamic stability of the austenite. At temperatures above 0,5Tm dislocation climb and diffusion of point defects become increasingly important and at these temperatures recovery, recrystallization and precipitation can also occur during deformation [fr

BUSINESS MODELLING AND DATABASE DESIGN IN CLOUD COMPUTING

Directory of Open Access Journals (Sweden)

Mihai-Constantin AVORNICULUI

2015-04-01

Full Text Available Electronic commerce is growing constantly from one year to another in the last decade, few are the areas that also register such a growth. It covers the exchanges of computerized data, but also electronic messaging, linear data banks and electronic transfer payment. Cloud computing, a relatively new concept and term, is a model of access services via the internet to distributed systems of configurable calculus resources at request which can be made available quickly with minimum management effort and intervention from the client and the provider. Behind an electronic commerce system in cloud there is a data base which contains the necessary information for the transactions in the system. Using business modelling, we get many benefits, which makes the design of the database used by electronic commerce systems in cloud considerably easier.

Carbon pellet cloud striations

International Nuclear Information System (INIS)

Parks, P.B.

1989-01-01

Fine scale striations, with alternating rows of bright and dark zones, have been observed in the ablation clouds of carbon pellets injected into the TEXT tokamak. The striations extend along the magnetic field for about 1 cm with quite regular cross-field variations characterized by a wavelength of a few mm. Their potential as a diagnostic tool for measuring q-profiles in tokamaks provides motivation for investigating the origin of the striations. The authors propose that the striations are not due to a sequence of high and low ablation rates because of the finite thermal magnetic islands localized at rational surfaces, q = m/n, would be responsible for reducing the electron flux to the pellet region; the length of the closed field line which forms the local magnetic axis of the island is too long to prevent a depletion of plasma electrons in a flux tube intercepting the pellet for the duration 2 rp / vp . Instead, they propose that striations are the manifestation of the saturated state of growing fluctuations inside the cloud. The instability is generated by E x B rotation of the ablation cloud. The outward centrifugal force points down the ablation density gradient inducing the Rayleigh-Taylor instability. The instability is not present for wave numbers along the field lines, which may explain why the striations are long and uniform in that direction. The E field develops inside the ablation cloud as a result of cold electron return currents which are induced to cancel the incoming hot plasma electron current streaming along the field lines

Comparison of Corrosion Behavior of Low-Alloy Steel Containing Copper and Antimony with 409L Stainless Steel for a Flue Gas Desulfurization System

Energy Technology Data Exchange (ETDEWEB)

Park, Sun-Ah; Shin, Su-Bin; Kim, Jung-Gu [Sungkyunkwan University, Suwon (Korea, Republic of)

2016-07-15

The corrosion behavior of low alloy steel containing Cu, Sb and 409L stainless steel was investigated for application in the low-temperature section of a flue gas desulfurization (FGD) system. The electrochemical properties were evaluated by potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS) in 16.9 vol% H{sub 2}SO{sub 4} + 0.35 vol% HCl at 60 ℃. The inclusions in these steels ere identified by electron probe microanalyzer (EPMA). The corrosion products of the steels were analyzed using scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The corrosion rate of the low alloy steel containing Cu, Sb was about 100 times lower than that of 409L stainless steel. For stainless steel without passivation, active corrosion behavior was shown. In contrast, in the low alloy steel, the Cu, Sb compounds accumulated on the surface improved the corrosion resistance by suppressing the anodic dissolution reaction.

Status of the experimental studies of the electron cloud at the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

2003-01-01

The electron cloud (EC) at the Los Alamos Proton Storage Ring (PSR) has been studied extensively for the past several years with an overall aim to identify and measure its important characteristics, the factors that influence these characteristics, and to relate these to the two-stream (e-p) transverse instability long observed at PSR. Some new results since PAC2001 are presented.

Environmental scanning electron microscopy analysis of Proteus mirabilis biofilms grown on chitin and stainless steel.

Science.gov (United States)

Fernández-Delgado, Milagro; Duque, Zoilabet; Rojas, Héctor; Suárez, Paula; Contreras, Monica; García-Amado, María A; Alciaturi, Carlos

Proteus mirabilis is a human pathogen able to form biofilms on the surface of urinary catheters. Little is known about P. mirabilis biofilms on natural or industrial surfaces and the potential consequences for these settings. The main aim of this work was to assess and compare the adhesion and biofilm formation of P. mirabilis strains from different origins on chitin and stainless steel surfaces within 4 to 96 h. Using environmental scanning electron microscopy, the biofilms of a clinical strain grown on chitin at 4 h showed greater adhesion, aggregation, thickness, and extracellular matrix production than those grown on stainless steel, whereas biofilms of an environmental strain had less aggregation on both surfaces. Biofilms of both P. mirabilis strains developed different structures on chitin, such as pillars, mushrooms, channels, and crystalline-like precipitates between 24 and 96 h, in contrast with flat-layer biofilms produced on stainless steel. Significant differences ( p  biofilm formation. This represents the first study of P. mirabilis showing adhesion, biofilm formation, and development of different structures on surfaces found outside the human host.

Compression of Antiproton Clouds for Antihydrogen Trapping

CERN Document Server

Andresen, G B; Bowe, P D; Bray, C C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Funakoshi, R; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Hydomako, R; Jenkins, M J; Jørgensen, L V; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; Van der Werf, D P; Wurtele, J S; Yamazaki, Y

2008-01-01

Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.

Characterization and understanding of ion irradiation effect on the microstructure of austenitic stainless steels

International Nuclear Information System (INIS)

Volgin, Alexandre

2012-01-01

Austenitic stainless steels are widely used in nuclear industry for internal structures. These structures are located close to the fuel assemblies, inside the pressure vessel. The exposure of these elements to high irradiation doses (the accumulated dose, after 40 years of operation, can reach 80 dpa), at temperature close to 350 C, modifies the macroscopic behavior of the steel: hardening, swelling, creep and corrosion are observed. Moreover, in-service inspections of some of the reactor internal structures have revealed the cracking of some baffle bolts. This cracking has been attributed to Irradiation Assisted Stress Corrosion Cracking (IASCC). In order to understand this complex phenomenon, a first step is to identify the microstructural changes occurring during irradiation, and to understand the mechanisms at the origin of this evolution. In this framework, a large part of the European project 'PERFORM 60' is dedicated to the study of the irradiation damage in austenitic stainless steels. The objective of this PhD work is to bring comprehensive data on the irradiation effects on microstructure. To reach this goal, two model alloys (FeNiCr and FeNiCrSi) and an industrial austenitic stainless steel (316 steel) are studied using Atom Probe Tomography (APT), Transmission Electron Microscope (TEM) and Positron Annihilation Spectroscopy (PAS). They are irradiated by Ni ions in CSNSM (Orsay) at two temperatures (200 and 450 C) and three doses (0.5, 1 and 5 dpa). TEM observations have shown the appearance of dislocation loops, cavities and staking fault tetrahedra. The dislocation loops in 316 steel were preferentially situated in the vicinity of dislocations, while they were randomly distributed in the FeNiCr alloy. APT study has shown the redistribution of Ni and Si under irradiation in FeNiCrSi model alloy and 316 steel, leading to the appearance of (a) Cottrell clouds along dislocation lines, dislocation loops and other non-identified crystalline defects and (b

Microstructural and Mechanical Characterization of Electron Beam Welded Joints of High Strength S960QL and Weldox 1300 Steel Grades

Directory of Open Access Journals (Sweden)

Błacha S.

2017-06-01

Full Text Available The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material.

Structure and properties of steel case-hardened by non-vacuum electron-beam cladding of carbon fibers

Science.gov (United States)

Losinskaya, A. A.; Lozhkina, E. A.; Bardin, A. I.

2017-12-01

At the present time, the actual problem of materials science is the increase in the steels performance characteristics. In the paper some mechanical properties of the case-hardened materials received by non-vacuum electron-beam cladding of carbon fibers are determined. The depth of the hardened layers varies from 1.5 to 3 mm. The impact strength of the samples exceeds 50 J/cm2. The wear resistance of the coatings obtained exceeds the properties of steel 20 after cementation and quenching with low tempering. The results of a study of the microhardness of the resulting layers and the microstructure are also given. The hardness of the surface layers exceeds 5700 MPa.

Rigid-body rotation of an electron cloud in divergent magnetic fields

International Nuclear Information System (INIS)

Fruchtman, A.; Gueroult, R.; Fisch, N. J.

2013-01-01

For a given voltage across a divergent poloidal magnetic field, two electric potential distributions, each supported by a rigid-rotor electron cloud rotating with a different frequency, are found analytically. The two rotation frequencies correspond to the slow and fast rotation frequencies known in uniform plasma. Due to the centrifugal force, the equipotential surfaces, that correspond to the two electric potential distributions, diverge more than the magnetic surfaces do, the equipotential surfaces in the fast mode diverge largely in particular. The departure of the equipotential surfaces from the magnetic field surfaces may have a significant focusing effect on the ions accelerated by the electric field. The focusing effect could be important for laboratory plasma accelerators as well as for collimation of astrophysical jets

Characterization by transmission electron microscopy of a JRQ steel subjected to different heat treatments

International Nuclear Information System (INIS)

Moreno G, N.

2014-01-01

In this work a study was conducted on the steel Astm A-533, Grade B, Class 1 of reference JRQ, for the purpose of carrying out a study by transmission electron microscopy on the size and distribution of precipitates in steel samples JRQ previously subjected to heat treatments. This because the reactor vessels of the nuclear power plant of Laguna Verde, are made of a steel Astm A-533 Grade B, Class 1. It is known that the neutron radiation causes damage primarily embrittlement in materials that are exposed to it. However, observable damage through mechanical tests result from microstructural defects and atomic, induced by the neutron radiation. In previous studies hardening by precipitation of a JRQ steel (provided by the IAEA) was induced by heat treatments, finding that the conditions of heat treatment that reproduce the hardness and stress mechanical properties of a steel Astm A-533, Grade B, Class 1 irradiated for 8 years to a fluence of 3.5 x 10 17 neutrons/cm 2 and to a temperature of 290 grades C are achieved with annealing treatments at 550 grades C. In the studied samples it was found that the more hardening phase both the heat treatments as the neutron radiation, is the bainite, being the ferrite practically unchanged. Which it gave the tone to believe that the ferrite is the phase that provides at level macro the mechanical properties in stress, since in the irradiated samples such properties remained unchanged with respect to the non-irradiated material, however changes were observed in material ductility, which may be attributable to the change of hardness in the bainite, which opens a possibility for modeling the micromechanical behavior of this material. (Author)

Effect of ausforming on nanobainite steel

International Nuclear Information System (INIS)

Gong, W.; Tomota, Y.; Koo, M.S.; Adachi, Y.

2010-01-01

The effect of ausforming on kinetics, morphology and crystallography of nanobainite steel was examined by electron backscattered diffraction and transmission electron microscopy. Ausforming has been found to accelerate bainite transformation at 573 K. A characteristic microstructure consisting of blocky bainitic laths and retained austenite is observed in the ausformed bainite steel, where strong variant selection takes place due to the operated slip systems.

Preparation and characterization of 304 stainless steel/Q235 carbon steel composite material

Directory of Open Access Journals (Sweden)

Wenning Shen

Full Text Available The composite material of 304 stainless steel reinforced Q235 carbon steel has been prepared by modified hot-rolling process. The resulted material was characterized by scanning electron microscope, three-electrode method, fault current impact method, electrochemical potentiodynamic polarization curve measurement and electrochemical impedance spectroscopy. The results showed that metallurgical bond between the stainless steel layer and carbon steel substrate has been formed. The composite material exhibited good electrical conductivity and thermal stability. The average grounding resistance of the composite material was about 13/20 of dip galvanized steel. There has no surface crack and bubbling formed after fault current impact. The composite material led to a significant decrease in the corrosion current density in soil solution, compared with that of hot dip galvanized steel and bare carbon steel. On the basis polarization curve and EIS analyses, it can be concluded that the composite material showed improved anti-corrosion property than hot-dip galvanized steel. Keywords: Stainless steel, Carbon steel, Anti-corrosion, Conductivity, Electrochemical, EIS

Physical conditions in CaFe interstellar clouds

OpenAIRE

Gnacinski, P.; Krogulec, M.

2007-01-01

Interstellar clouds that exhibit strong Ca I and Fe I lines were called CaFe clouds. The ionisation equilibrium equations were used to model the column densities of Ca II, Ca I, K I, Na I, Fe I and Ti II in CaFe clouds. The chemical composition of CaFe clouds is that of the Solar System and no depletion of elements onto dust grains is seen. The CaFe clouds have high electron densities n=1 cm^-3 that leads to high column densities of neutral Ca and Fe.

Preparation and characterization of 304 stainless steel/Q235 carbon steel composite material

Science.gov (United States)

Shen, Wenning; Feng, Lajun; Feng, Hui; Cao, Ying; Liu, Lei; Cao, Mo; Ge, Yanfeng

The composite material of 304 stainless steel reinforced Q235 carbon steel has been prepared by modified hot-rolling process. The resulted material was characterized by scanning electron microscope, three-electrode method, fault current impact method, electrochemical potentiodynamic polarization curve measurement and electrochemical impedance spectroscopy. The results showed that metallurgical bond between the stainless steel layer and carbon steel substrate has been formed. The composite material exhibited good electrical conductivity and thermal stability. The average grounding resistance of the composite material was about 13/20 of dip galvanized steel. There has no surface crack and bubbling formed after fault current impact. The composite material led to a significant decrease in the corrosion current density in soil solution, compared with that of hot dip galvanized steel and bare carbon steel. On the basis polarization curve and EIS analyses, it can be concluded that the composite material showed improved anti-corrosion property than hot-dip galvanized steel.

Characterization of an Additive Manufactured TiAl Alloy-Steel Joint Produced by Electron Beam Welding.

Science.gov (United States)

Basile, Gloria; Baudana, Giorgio; Marchese, Giulio; Lorusso, Massimo; Lombardi, Mariangela; Ugues, Daniele; Fino, Paolo; Biamino, Sara

2018-01-17

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti₃Al followed by Al₃NiTi₂ and AlNi₂Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached.

Enhanced corrosion resistance of strontium hydroxyapatite coating on electron beam treated surgical grade stainless steel

Energy Technology Data Exchange (ETDEWEB)

Gopi, D., E-mail: dhanaraj_gopi@yahoo.com [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Centre for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamilnadu (India); Rajeswari, D. [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); Ramya, S. [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Sekar, M. [Department of Chemistry, Periyar University, Salem 636 011, Tamilnadu (India); Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); R, Pramod; Dwivedi, Jishnu [Industrial and Medical Accelerator Section, Raja Ramanna Centre for Advanced Technology, Indore 452 013, Madhya Pradesh (India); Kavitha, L., E-mail: louiskavitha@yahoo.co.in [Centre for Nanoscience and Nanotechnology, Periyar University, Salem 636 011, Tamilnadu (India); Department of Physics, Periyar University, Salem 636 011, Tamilnadu (India); Ramaseshan, R. [Thin film and Coatings Section, Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India)

2013-12-01

The surface of 316L stainless steel (316L SS) is irradiated by high energy low current DC electron beam (HELCDEB) with energy of 500 keV and beam current of 1.5 mA followed by the electrodeposition of strontium hydroxyapatite (Sr-HAp) to enhance its corrosion resistance in physiological fluid. The coatings were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and High resolution scanning electron microscopy (HRSEM). The Sr-HAp coating on HELCDEB treated 316L SS exhibits micro-flower structure. Electrochemical results show that the Sr-HAp coating on HELCDEB treated 316L SS possesses maximum corrosion resistance in Ringer's solution.

Enhanced corrosion resistance of strontium hydroxyapatite coating on electron beam treated surgical grade stainless steel

Science.gov (United States)

Gopi, D.; Rajeswari, D.; Ramya, S.; Sekar, M.; R, Pramod; Dwivedi, Jishnu; Kavitha, L.; Ramaseshan, R.

2013-12-01

The surface of 316L stainless steel (316L SS) is irradiated by high energy low current DC electron beam (HELCDEB) with energy of 500 keV and beam current of 1.5 mA followed by the electrodeposition of strontium hydroxyapatite (Sr-HAp) to enhance its corrosion resistance in physiological fluid. The coatings were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and High resolution scanning electron microscopy (HRSEM). The Sr-HAp coating on HELCDEB treated 316L SS exhibits micro-flower structure. Electrochemical results show that the Sr-HAp coating on HELCDEB treated 316L SS possesses maximum corrosion resistance in Ringer's solution.

Charging dynamics and strong localization of a two-dimensional electron cloud

International Nuclear Information System (INIS)

Dianoux, R; Smilde, H J H; Marchi, F; Buffet, N; Mur, P; Comin, F; Chevrier, J

2007-01-01

The dynamics of charge injection in silicon nanocrystals embedded in a silicon dioxide matrix is studied using electrostatic force microscopy. We show that the presence of silicon nanocrystals with a density of 10 11 cm -2 is essential for strong localization of charges, and results in exceptional charge retention properties compared to nanocrystal-free SiO 2 samples. In both systems, a logarithmic dependence of the diameter of the charged area on the injection time is experimentally observed on a timescale between 0.1 and 10 s (voltage≤10 V). A field-emission injection, limited by Coulomb blockade and a lateral charge spreading due to a repulsive radial electric field are used to model the sample charging. Once the tip is retracted, the electron cloud is strongly confined in the nanocrystals and remains static

How to build a cloud chamber?

International Nuclear Information System (INIS)

Mariaud, C.

2012-01-01

The cloud chamber had its heyday in the first half of last century and allowed the discovery of new particles such as the anti-electron, the muon and the neutral and the charged kaon. The bubble chamber replaced it in the mid fifties. This article recalls the principle of the cloud chamber and shows, in a detailed way, how to proceed to build one with on-the-shelf materials. This design is based on the use of isopropanol whose liquefaction through the form of droplets materializes the track of the particle and on the use of combined Peltier cells (instead of CO 2 snow) to cool the chamber. This cloud chamber has been successfully used in schools to observe particles mainly electrons, alphas and muons generated by cosmic rays. (A.C.)

Characterization of an Additive Manufactured TiAl Alloy—Steel Joint Produced by Electron Beam Welding

Directory of Open Access Journals (Sweden)

Gloria Basile

2018-01-01

Full Text Available In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at % alloy part was produced by Electron Beam Melting (EBM. This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti3Al followed by Al3NiTi2 and AlNi2Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached.

Transmission electron microscopy characterization of the interfacial structure of a galvanized dual-phase steel

Energy Technology Data Exchange (ETDEWEB)

Aslam, I., E-mail: ia31@msstate.edu [Center for Advanced Vehicular Systems, Mississippi State University, MS 39759 (United States); Department of Mechanical Engineering, Mississippi State University, MS 39762 (United States); Li, B. [Center for Advanced Vehicular Systems, Mississippi State University, MS 39759 (United States); Department of Chemical and Materials Engineering, University of Nevada, Reno, NV 89557 (United States); Martens, R.L.; Goodwin, J.R. [Central Analytical Facility, the University of Alabama, Tuscaloosa, AL 35487 (United States); Rhee, H.J. [Center for Advanced Vehicular Systems, Mississippi State University, MS 39759 (United States); Department of Mechanical Engineering, Mississippi State University, MS 39762 (United States); Goodwin, F. [International Zinc Association, Durham, NC 27713 (United States)

2016-10-15

Site-specific studies were carried out to characterize the interface of a galvanized dual-phase (DP) steel. Focused ion beam (FIB) was used to prepare specimens in the interface region (~ 100 nm thick) between the coating and the substrate. Transmission electron microscopy (TEM), scanning TEM (STEM), and high resolution TEM (HRTEM) were performed to resolve the phases and the structures at the interface between the zinc (Zn) coating and the steel substrate. The STEM and TEM results showed that a continuous manganese oxide (MnO) film with a thickness of ~ 20 nm was present on the surface of the substrate while no silicon (Si) oxides were resolved. Internal oxide particles were observed as well in the sub-surface region. Despite the presence of the continuous oxide film, a well-developed inhibition layer was observed right on top of the oxide film. The inhibition layer has a thickness of ~ 100 nm. Possible mechanisms for the growth of the inhibition layer were discussed. - Highlights: •Site-specific examinations were performed on the Zn/steel interface. •Continuous external MnO oxides (20 nm) were observed at the interface. •No Si oxides were observed at the interface. •Internal oxide particles were distributed in the subsurface. •A continuous inhibition layer grew on top of the external oxides.

Correlating electronic structure with corrosion inhibition potentiality of some bis-benzimidazole derivatives for mild steel in hydrochloric acid: Combined experimental and theoretical studies

International Nuclear Information System (INIS)

Dutta, Alokdut; Saha, Sourav Kr.; Banerjee, Priyabrata; Sukul, Dipankar

2015-01-01

Highlights: • Bis-benzimidazole derivatives as good corrosion inhibitors for mild steel in acid. • Simultaneous both way electron-transfer is expected to occur during adsorption. • Role of molecular conformation on inhibition efficiency is demonstrated. • Good correlation between inhibition efficiency and molecular parameters established. • MD simulation results support experimental observations. - Abstract: Four different bis-benzimidazole (BBI) derivatives, tested as potential corrosion inhibitors for mild steel in 1 M HCl, have revealed good inhibition efficiency for long period of exposure. Inhibitors impart high resistance towards charge transfer across metal–electrolyte interface and behave broadly as mixed type. DFT calculations are used to correlate inhibition potentiality with intrinsic molecular parameters. From the optimized geometry of BBI derivatives, electron distribution in HOMO and LUMO and Fukui indices of each atom, possible modes of interaction of BBI derivatives with mild steel surface have been predicted. Energy corresponding to inhibitor-metal surface interaction is evaluated following molecular dynamics simulation

Conversion electron Moessbauer spectroscopy of plasma immersion ion implanted H13 tool steel

International Nuclear Information System (INIS)

Terwagne, G.; Hutchings, R.

1994-01-01

Conversion electron Moessbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI 3 ) at 350 C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ε-Fe 2 N through ε-Fe 3 N to γ'-Fe 4 N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone. (orig.)

Electron pulsed beam induced processing of thin film surface by Nb3Ge deposited into a stainless steel tape

International Nuclear Information System (INIS)

Vavra, I.; Korenev, S.A.

1988-01-01

A surface of superconductive thin film of Nb 3 Ge deposited onto a stainless steel tape was processed using the electron beam technique. The electron beam used had the following parameters: beam current density from 400 to 1000 A/cm 2 ; beam energy 100 keV; beam impulse length 300 ns. By theoretical analysis it is shown that the heating of film surface is an adiabatic process. It corresponds to our experimental data and pictures showing a surface remelting due to electron beam influence. After beam processing the superconductive parameters of the film remain unchanged. Roentgenograms have been analysed of Nb 3 Ge film surface recrystallized due to electron beam influence

Simulation studies on the electron cloud build-up in the elements of the LHC Arcs at 6.5 TeV

CERN Document Server

Dijkstal, Philipp; Mether, Lotta; Rumolo, Giovanni; CERN. Geneva. ATS Department

2017-01-01

The formation of electron clouds in the arcs of the Large Hadron Collider (LHC) has been identified as one of the main limitations for the performance of the machine. In particular, the impacting electrons can deposit a significant power on the cold beam screens of the LHC superconducting magnets, which translates into a significant heat load for the cryogenic system. A detailed model of the e-cloud formation in the different elements of the LHC arc half-cell has been developed using the PyECLOUD simulation code. The model includes the main dipole and quadrupole magnets, shorter corrector magnets and drift spaces. Particular care was taken to correctly model the impact of the hotoelectrons produced by the beam synchrotron radiation. For this purpose, we reviewed the available literature on the characterization of the LHC beam screen surface in terms of reflectivity and photoelectron yield and we defined the necessary steps to obtain the photoemission model in the format required in input by t...

Corrosion characteristics of DMR-1700 steel and comparison with different steels in marine environment

International Nuclear Information System (INIS)

Gurrappa, I.; Malakondaiah, G.

2005-01-01

In the present paper, a systematic corrosion study has been carried out on DMR-1700 steel to understand the protective nature of oxide scale that forms on its surface under marine environmental conditions. Further, the studies related to oxide scales as well as pitting and crevice corrosion resistance of both stainless steels and widely used low alloy steel EN24 in marine environment have been studied for comparison purpose. The surface morphologies of corroded steels have been observed under scanning electron microscope (SEM) in order to understand the nature of corrosion. A high performance protective coating that has been developed for protection of low alloy steels DMR-1700 and EN24 against corrosion is presented after stressing the importance of surface engineering in enhancing the life of steels. Based on the studies with different techniques, DMR-1700 steel has been recommended for manufacture of components used in aerospace systems in association with appropriate protective coating for improving their efficiency

The Electronic Forensics Process under Cloud Environment%云环境下电子取证方式与流程

Institute of Scientific and Technical Information of China (English)

骆智森

2015-01-01

in recent years, with the continuous development of cloud computing technology, our life also because cloud computing function has been a lot of convenience, convenient our daily some important information preservation. But the network also ap⁃peared a lot of for cloud computing or cloud computing to steal the target of cyber crime, both at the technical level or in law, cloud computing is gaining achievements is still not big enough, it also gives the cloud computing network security left a loophole. Rising trend of cyber crime, for a criminal record has been unable to use traditional methods of electronic evidence for forensic evidence, which for the evidence is a difficult challenge. Therefore, this paper will be electronic evidence of cloud computing research and analysis. At first, this paper analyzes the difficulty of obtaining evidence under the environment of cloud computing, then pointed out that the cloud computing environment of the primary collection objects, in the end, this article presents a new kind of cloud fo⁃rensics forensic methods. The final result of this article will evidence to bring a lot of convenience, can also provide some reference for the cloud forensics forensic investigators.%近年来，随着云计算技术的不断发展，我们的生活也因为云计算功能得到了很多的便利，方便我们日常的一些重要信息保存。可是网络上也出现了大量的针对云计算或以云计算为窃取目标的网络犯罪，无论是在技术层面还是在法律方面，云计算取得的成就还是不够大，这也给云计算的网络安全留下了一个漏洞。网络犯罪的趋势不断上涨，对犯罪记录进行取证的人员已经无法用传统的电子取证方法为案件取证，这对取证人员来说，是一个困难的挑战。因此，该文将会对云计算的电子取证进行探究和分析。该文首先分析了云计算环境下取证的困难，之后便点明了云计算环境下的首要取证对象，在最后，文章会提出一种新的有关云取证的取证方法。本篇文章的最终研究成果会给取证人员带来很多的便利，也可以为进行云取证的取证人员提供一些参考。

Carbon footprint of electronic devices

Science.gov (United States)

Sloma, Marcin

2013-07-01

Paper assesses the greenhouse gas emissions related to the electronic sectors including information and communication technology and media sectors. While media often presents the carbon emission problem of other industries like petroleum industry, the airlines and automobile sectors, plastics and steel manufacturers, the electronics industry must include the increasing carbon footprints caused from their applications like media and entertainment, computers and cooling devices, complex telecommunications networks, cloud computing and powerful mobile phones. In that sense greenhouse gas emission of electronics should be studied in a life cycle perspective, including regular operational electricity use. Paper presents which product groups or processes are major contributors in emission. From available data and extrapolation of existing information we know that the information and communication technology sector produced 1.3% and media sector 1.7% of global gas emissions within production cycle, using the data from 2007.In the same time global electricity use of that sectors was 3.9% and 3.2% respectively. The results indicate that for both sectors operation leads to more gas emissions than manufacture, although impacts from the manufacture is significant, especially in the supply chain. Media electronics led to more emissions than PCs (manufacture and operation). Examining the role of electronics in climate change, including disposal of its waste, will enable the industry to take internal actions, leading to lowering the impact on the climate change within the sector itself.

Crystallographic orientation study of silicon steels using X-ray diffraction, electrons diffraction and the Etch Pit method

International Nuclear Information System (INIS)

Santos, Hamilta de Oliveira

1999-01-01

The aim of the present study is the microstructural and crystallographic orientation of Fe-3%Si steel. The silicon steel shows good electrical properties and it is used in the nuclear and electrical power fields. The studied steel was supplied by Cia. Acos Especiais Itabira S/A - ACESITA. The material was received in the hot compressed condition, in one or two passes. The hot compressing temperatures used were 900, 1000 and 1100 deg C with soaking times ranging from 32 to 470 s. The material preferential crystallographic orientation was evaluated in every grain of the samples. The characterization techniques used were: scanning electron microscopy (SEM) using the etch pit method; X ray diffraction using the Laue back-reflection method; orientation imaging microscopy (OIM). Microstructural characterization in terms of grain size measurement and mean number of grains in the sample were also undertaken. The Laue method was found an easy technique to access crystallographic orientation of this work polycrystalline samples 2.5 mm average grain size. This was due to the inability to focus the X-rays on a single grain of the material. The scanning electron microscopy showed microcavities left by the etch pit method, which allowed the observation of the crystallographic orientation of each grain from the samples. No conclusive grain crystallographic orientation was possible to obtain by the OIM technique due to the non-existing rolling direction. A more extensive work with the OIM technique must be undertaken on the Fe-3%Si with oriented grains and non oriented grains. (author)

Vacancy defects in electron irradiated RPV steels studied by positron lifetime

Energy Technology Data Exchange (ETDEWEB)

Moser, P; Li, X H [CEA Centre d` Etudes de Grenoble, 38 (France). Dept. de Recherche Fondamentale sur la Matiere Condensee; Akamatsu, M; Van Duysen, J C [Electricite de France (EDF), 77 - Ecuelles (France)

1994-12-31

Specimens of French RPV (reactor pressure vessels) steels at different rates of segregation have been irradiated at 150 and 288 deg C with 3 MeV electrons (irradiation dose: 4*10{sup 19} e-/cm{sup 2}). Vacancy defects are studied by positron lifetime measurements before and after irradiation and at each step of isochronal annealing. After 150 deg C irradiation, a recovery step is observed in both specimens, for annealing treatments in the range 220-370 deg C and is attributed to the dissociation of vacancy-impurity complexes. The size of vacancy clusters never overcome 10 empty atomic volumes. If ``fresh`` dislocations are created just before irradiation, big vacancy clusters could be formed. After 288 deg C irradiation, small vacancy cluster of 4-10 empty atomic volumes are observed. (authors). 3 figs., 7 refs.

A comparison and benchmark of two electron cloud packages

Energy Technology Data Exchange (ETDEWEB)

Lebrun, Paul L.G.; Amundson, James F; Spentzouris, Panagiotis G; Veitzer, Seth A

2012-01-01

We present results from precision simulations of the electron cloud (EC) problem in the Fermilab Main Injector using two distinct codes. These two codes are (i)POSINST, a F90 2D+ code, and (ii)VORPAL, a 2D/3D electrostatic and electromagnetic code used for self-consistent simulations of plasma and particle beam problems. A specific benchmark has been designed to demonstrate the strengths of both codes that are relevant to the EC problem in the Main Injector. As differences between results obtained from these two codes were bigger than the anticipated model uncertainties, a set of changes to the POSINST code were implemented. These changes are documented in this note. This new version of POSINST now gives EC densities that agree with those predicted by VORPAL, within {approx}20%, in the beam region. The root cause of remaining differences are most likely due to differences in the electrostatic Poisson solvers. From a software engineering perspective, these two codes are very different. We comment on the pros and cons of both approaches. The design(s) for a new EC package are briefly discussed.

Investigation of instability of M23C6 particles in F82H steel under electron and ion irradiation conditions

Science.gov (United States)

Kano, Sho; Yang, Huilong; Shen, Jingjie; Zhao, Zishou; McGrady, John; Hamaguchi, Dai; Ando, Mamami; Tanigawa, Hiroyasu; Abe, Hiroaki

2018-04-01

In order to clarify the instability of M23C6 in F82H steel under irradiation, both electron irradiation using a high voltage electron microscope (HVEM) and ion irradiation using an ion accelerator were performed. For the electron irradiation, in-situ observation under 2 MV electron irradiation and ex-situ high resolution electron microscopic (HREM) analysis were utilized to evaluate the response of M23C6 against irradiation. The temperature dependence of the irradiation induced instability of the carbide was first confirmed: 293 K indicating severe loss of crystallinity due to dissolution of the constituent atoms though irradiation-enhanced diffusion under the vacancy diffusion by the focused electron beam irradiation. For the ion irradiation, 10.5 MeV-Fe3+ ion was applied to bombard the F82H steel at 673 K to achieve the displacement damage of ≈20 dpa at the depth of 1.0 μm from surface. Cross-section TEM specimens were prepared by a focused ion beam technique. The shrinkage of carbide particles was observed especially near the irradiation surface. Besides, the lattice fringes at the periphery of carbide were observed in the irradiated M23C6 by the HREM analysis, which is different from that observed in the electron irradiation. It was clarified that the instability of M23C6 is dependent on the irradiation conditions, indicating that the flow rate of vacancy type defects might be the key factor to cause the dissolution of constituent atoms of carbide particles into matrix under irradiation.

Effect of the LHC Beam Screen Baffle on the Electron Cloud Buildup

CERN Document Server

Romano, Annalisa; Li, Kevin; Rumolo, Giovanni

2016-01-01

Electron Cloud (EC) has been identified as one of the major intensity-limiting factors in the CERN Large Hadron Collider (LHC). Due to the EC, an additional heat load is deposited on the perforated LHC beam screen, for which only a small cooling capacity is available. In order to preserve the superconducting state of the magnets, pumping slots shields were added on the outer side of the beam screens. In the framework of the design of the beam screens of the new HL-LHC triplets, the impact of these shields on the multipacting process was studied with macroparticle simulations. For this purpose multiple new features had to be introduced in the PyECLOUD code. This contribution will describe the implemented simulation model and summarize the outcome of this study.

Formation Energies and Electronic Properties of Vanadium Carbides Found in High Strength Steel Alloys

Science.gov (United States)

Limmer, Krista; Medvedeva, Julia

2013-03-01

Carbide formation and stabilization in steels is of great interest owing to its effect on the microstructure and properties of the Fe-based alloys. The appearance of carbides with different metal/C ratios strongly depends on the carbon concentration, alloy composition as well as the heat treatment. Strong carbide-forming elements such as Ti, V, and Nb have been used in microalloyed steels; with VC showing an increased solubility in the iron matrix as compared with TiC and NbC. This allows for dissolution of the VC into the steel during heating and fine precipitation during cooling. In addition to VC, the primary vanadium carbide with cubic structure, a wide range of non-stoichiometric compositions VCy with y varying from 0.72 to 0.88, has been observed. This range includes two ordered compounds, V8C7 and V6C5. In this study, first-principles density functional theory (DFT) is employed to examine the stability of the binary carbides by calculating their formation energies. We compare the local structures (atomic coordination, bond distances and angles) and the density of states in optimized geometries of the carbides. Further, the effect of alloying additions, such as niobium and titanium, on the carbide stabilization is investigated. We determine the energetically preferable substitutional atom location in each carbide and study the impurity distribution as well as its role in the carbide formation energy and electronic structure.

Weldability of Stainless Steels

International Nuclear Information System (INIS)

Saida, Kazuyoshi

2010-01-01

It gives an outline of metallographic properties of welding zone of stainless steels, generation and mechanisms of welding crack and decreasing of corrosion resistance of welding zone. It consists of seven chapters such as introduction, some kinds of stainless steels and properties, metallographic properties of welding zone, weld crack, toughness of welding zone, corrosion resistance and summary. The solidification modes of stainless steels, each solidification mode on the cross section of Fe-Cr-Ni alloy phase diagram, each solidification mode of weld stainless steels metal by electron beam welding, segregation state of alloy elements at each solidification mode, Schaeffler diagram, Delong diagram, effects of (P + S) mass content in % and Cr/Ni equivalent on solidification cracking of weld stainless steels metal, solidification crack susceptibility of weld high purity stainless steels metal, effects of trace impurity elements on solidification crack susceptibility of weld high purity stainless steels metal, ductile fracture susceptibility of weld austenitic stainless steels metal, effects of H2 and ferrite content on generation of crack of weld 25Cr-5N duplex stainless steels, effects of O and N content on toughness of weld SUS 447J1 metals, effect of ferrite content on aging toughness of weld austenitic stainless steel metal, corrosion morphology of welding zone of stainless steels, generation mechanism of knife line attack phenomenon, and corrosion potential of some kinds of metals in seawater at room temperature are illustrated. (S.Y.)

Change of structure, microstructure and mechanical properties of steels after electron-beam quenching using new technology

International Nuclear Information System (INIS)

Tsenker, R.; Yun, V.; Rat'en, D.; Fritshe, G.

1988-01-01

Main principles and technological possibilities of a new method for electron-beam treatment are presented. The method lies in local-time high-frequency scanning of electron beam (surface-isothermal energy transfer). The method can be used for quenching of the band with up to 30(50) mm width and up to 1.5(2.0) mm depth of quenched layer. Changes of structure, microstructure and properties were investigated with the use of the following methods: surface sounding, light microscopy, scanning electron microscopy, X-ray phase analysis, X-ray radiographic analysis of internal stresses, macrohardness, microhardness and recording hardness measuring. A study was made on the effect of parameters of electron-beam quenching of steel (S45, 55St1, S100.1, 90MnV8, 100ST6) basic state on quenched layer depth, surface relief, martensite morphology, residual austenite amount, austenite grain system, internal stresses, hardness profiles and determined hardness

Model of E-Cloud Instability in the Fermilab Recycler

Energy Technology Data Exchange (ETDEWEB)

Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2015-06-24

Simple model of electron cloud is developed in the paper to explain e-cloud instability of bunched proton beam in the Fermilab Recycler. The cloud is presented as an immobile snake in strong vertical magnetic field. The instability is treated as an amplification of the bunch injection errors from the batch head to its tail. Nonlinearity of the e-cloud field is taken into account. Results of calculations are compared with experimental data demonstrating good correlation.

Transmission electron microscopy study of the heavy-ion-irradiation-induced changes in the nanostructure of oxide dispersion strengthened steels

Science.gov (United States)

Rogozhkin, S. V.; Bogachev, A. A.; Orlov, N. N.; Korchuganova, O. A.; Nikitin, A. A.; Zaluzhnyi, A. G.; Kozodaev, M. A.; Kulevoy, T. V.; Kuibeda, R. P.; Fedin, P. A.; Chalykh, B. B.; Lindau, R.; Hoffman, Ya.; Möslang, A.; Vladimirov, P.; Klimenkov, M.

2017-07-01

Transmission electron microscopy was used to study the effect of heavy-ion irradiation on the structure and the phase state of three oxide dispersion strengthened (ODS) steels: ODS Eurofer, ODS 13.5Cr, and ODS 13.5Cr-0.3Ti (wt %). Samples were irradiated with iron and titanium ions to fluences of 1015 and 3 × 1015 cm-2 at 300, 573, and 773 K. The study of the region of maximum radiation damage shows that irradiation increases the number density of oxide particles in all samples. The fraction of fine inclusions increases in the particle size distribution. This effect is most pronounced in the ODS 13.5Cr steel irradiated with titanium ions at 300 K to a fluence of 3 × 1015 cm-2. It is demonstrated that oxide inclusions in ODS 13.5Cr-0.3Ti and ODS 13.5Cr steels are more stable upon irradiation at 573 and 773 K than upon irradiation at 300 K.

Hot rolling and annealing effects on the microstructure and mechanical properties of ODS austenitic steel fabricated by electron beam selective melting

Science.gov (United States)

Gao, Rui; Ge, Wen-jun; Miao, Shu; Zhang, Tao; Wang, Xian-ping; Fang, Qian-feng

2016-03-01

The grain morphology, nano-oxide particles and mechanical properties of oxide dispersion strengthened (ODS)-316L austenitic steel synthesized by electron beam selective melting (EBSM) technique with different post-working processes, were explored in this study. The ODS-316L austenitic steel with superfine nano-sized oxide particles of 30-40 nm exhibits good tensile strength (412 MPa) and large total elongation (about 51%) due to the pinning effect of uniform distributed oxide particles on dislocations. After hot rolling, the specimen exhibits a higher tensile strength of 482 MPa, but the elongation decreases to 31.8% owing to the introduction of high-density dislocations. The subsequent heat treatment eliminates the grain defects induced by hot rolling and increases the randomly orientated grains, which further improves the strength and ductility of EBSM ODS-316L steel.

Ku/Ka/W-band Antenna for Electronically-Scanned Cloud and Precipitation Radar

Data.gov (United States)

National Aeronautics and Space Administration — Previously, cloud radars such as CloudSat have been separated from precipitation radars such as TRMM (Tropical Rainfall Measurement Mission) and GPM (Global...

Electron microscopy study of microstructure of the oxide-dispersion-strengthed steel

International Nuclear Information System (INIS)

Xing, H.; Sun, J.; Zhou, Z.J.

2010-01-01

The microstructure of the ODS ferritic-martensitic steel with chemical composition of Fe-12Cr-2W-0.5Ti-0.2V-0.2Si-0.13C-0.35Y 2 O 3 wt% fabricated by MA and HIP has been investigated by TEM. The emphasis is focused on the structure and chemical composition of the fine ODS particles and inclusions. The results showed that two types of complex ODS particles such as Y-Ti-O and Y-Si-O with nanometer size distribute homogeneously and incoherently in the matrix of the steel. Additionally, large (Ti,V)N inclusions were observed in the steel. The results of microstructural characterization are discussed to correlate with the processing and mechanical properties of the ODS steel. (author)

Deleterious phases precipitation on superduplex stainless steel UNS S32750: characterization by light optical and scanning electron microscopy

Directory of Open Access Journals (Sweden)

Juan Manuel Pardal

2010-09-01

Full Text Available Deleterious phases precipitation in superduplex stainless steels is the main concern in fabrication by welding and hot forming of this class of material. Sigma, chi and secondary austenite phases are considered deleterious phases because they produce negative effects on corrosion resistance. Besides, sigma and chi phases also promote strong decrease of toughness. In the present work, the precipitations of sigma, chi and secondary austenite under aging in the 800-950 °C interval were studied in two UNS S32750 steels with different grain sizes. The deleterious phases could be quantified by light optical microscopy, with no distinction between them. Scanning electron microscopy was used to distinguish the individual phases in various aging conditions. The results elucidate the influence of the aging temperature and grain size on the kinetics precipitation and morphology of deleterious phases. The kinetics of deleterious phases is higher in the fine grained material in the initial stage of aging, but the maximum amount of deleterious phases is higher in the coarse grained steel.

Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Venturini, M.

2011-01-01

The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons.

Simulation and experimental studies on electron cloud effects in particle accelerators

CERN Document Server

Romano, Annalisa; Cimino, Roberto; Iadarola, Giovanni; Rumolo, Giovanni

Electron Cloud (EC) effects represent a serious limitation for particle accelerators operating with intense beams of positively charged particles. This Master thesis work presents simulation and experimental studies on EC effects carried out in collaboration with the European Organization for Nuclear Research (CERN) in Geneva and with the INFN-LNF laboratories in Frascati. During the Long Shut- down 1 (LS1, 2013-2014), a new detector for EC measurements has been installed in one of the main magnets of the CERN Proton Synchrotron (PS) to study the EC formation in presence of a strong magnetic field. The aim is to develop a reli- able EC model of the PS vacuum chamber in order to identify possible limitation for the future high intensity and high brightness beams foreseen by Large Hadron Collider (LHC) Injectors Upgrade (LIU) project. Numerical simulations with the new PyECLOUD code were performed in order to quantify the expected signal at the detector under different beam conditions. The experimental activity...

Conversion electron Mössbauer spectroscopy of plasma immersion ion implanted H13 tool steel

Science.gov (United States)

Terwagne, G.; Collins, G. A.; Hutchings, R.

1994-12-01

Conversion electron Mössbauer spectroscopy (CEMS) has been used to investigate nitride formation in AISI-H13 tool steel after treatment by plasma immersion ion implantation (PI3) at 350 °C. With only slight variation in the plasma conditions, it is possible to influence the kinetics of nitride precipitation so as to obtain nitrogen concentrations that range from those associated with ɛ-Fe2N through ɛ-Fe3N to γ'-Fe4N. The CEMS results enable a more definite identification of the nitrides than that obtained by glancing-angle X-ray diffraction and nuclear reaction analysis alone.

Status report on the 'Merging' of the Electron-Cloud Code POSINST with the 3-D Accelerator PIC CODE WARP

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Azevedo, A.W.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Stoltz, P.H.

2004-01-01

We have integrated the electron-cloud code POSINST [1] with WARP [2]--a 3-D parallel Particle-In-Cell accelerator code developed for Heavy Ion Inertial Fusion--so that the two can interoperate. Both codes are run in the same process, communicate through a Python interpreter (already used in WARP), and share certain key arrays (so far, particle positions and velocities). Currently, POSINST provides primary and secondary sources of electrons, beam bunch kicks, a particle mover, and diagnostics. WARP provides the field solvers and diagnostics. Secondary emission routines are provided by the Tech-X package CMEE

Investigation on AISI 304 austenitic stainless steel to AISI 4140 low alloy steel dissimilar joints by gas tungsten arc, electron beam and friction welding

International Nuclear Information System (INIS)

Arivazhagan, N.; Singh, Surendra; Prakash, Satya; Reddy, G.M.

2011-01-01

Research highlights: → Beneficial effects of FRW, GTAW and EBW joints of dissimilar AISI 304 and AISI 4140 materials. → Comparative study of FRW, GTAW and EBW joints on mechanical properties. → SEM/EDAX, XRD analysis on dissimilar AISI 304 and AISI 4140 materials. -- Abstract: This paper presents the investigations carried out to study the microstructure and mechanical properties of AISI 304 stainless steel and AISI 4140 low alloy steel joints by Gas Tungsten Arc Welding (GTAW), Electron Beam Welding (EBW) and Friction Welding (FRW). For each of the weldments, detailed analysis was conducted on the phase composition, microstructure characteristics and mechanical properties. The results of the analysis shows that the joint made by EBW has the highest tensile strength (681 MPa) than the joint made by GTAW (635 Mpa) and FRW (494 Mpa). From the fractographs, it could be observed that the ductility of the EBW and GTA weldment were higher with an elongation of 32% and 25% respectively when compared with friction weldment (19%). Moreover, the impact strength of weldment made by GTAW is higher compared to EBW and FRW.

Effects of accelerated electron beam irradiation on surface hardening and fatigue properties in an AISI 4140 steel used for automotive crankshaft

Energy Technology Data Exchange (ETDEWEB)

Choo, S.-H.; Lee, S. [Pohang Univ. of Sci. and Technol. (Korea). Center for Adv. Aerospace Mater.; Golkovski, M.G. [Rossijskaya Akademiya Nauk, Novosibirsk (Russian Federation). Inst. Yadernoj Fiziki

2000-11-30

This study is concerned with the effects of high-energy accelerated electron beam irradiation on surface hardening and improvement of fatigue properties in an AISI 4140 steel currently used for automotive crankshaft. The 4140 steel specimens were irradiated in air by using a high-energy electron beam accelerator, and then microstructure, hardness, and fatigue properties were examined. Beam power was varied in the range of 5.2{proportional_to}7.7 kW by changing beam current. Upon irradiation, the unirradiated microstructure containing band structure was changed to martensite and bainite in the carbon-rich zone or ferrite, bainite, and martensite in the carbon-depleted zone. This microstructural modification improved greatly surface hardness and fatigue properties due to transformation of martensite whose amount and type were determined by heat input during irradiation. Thus, high-energy electron beam irradiation can be effectively applied to the surface hardening process of automotive parts. In order to investigate the thermal cycle during electron beam irradiation of quickly rotating specimens, the thermal analysis was also carried out using an analytical computer simulation. Analytical solutions gave information about the peak temperature, heating and cooling rate, and hardened depth to correlate with the overall microstructural modification. (orig.)

Confidentiality Protection of Digital Health Records in Cloud Computing.

Science.gov (United States)

Chen, Shyh-Wei; Chiang, Dai Lun; Liu, Chia-Hui; Chen, Tzer-Shyong; Lai, Feipei; Wang, Huihui; Wei, Wei

2016-05-01

Electronic medical records containing confidential information were uploaded to the cloud. The cloud allows medical crews to access and manage the data and integration of medical records easily. This data system provides relevant information to medical personnel and facilitates and improve electronic medical record management and data transmission. A structure of cloud-based and patient-centered personal health record (PHR) is proposed in this study. This technique helps patients to manage their health information, such as appointment date with doctor, health reports, and a completed understanding of their own health conditions. It will create patients a positive attitudes to maintain the health. The patients make decision on their own for those whom has access to their records over a specific span of time specified by the patients. Storing data in the cloud environment can reduce costs and enhance the share of information, but the potential threat of information security should be taken into consideration. This study is proposing the cloud-based secure transmission mechanism is suitable for multiple users (like nurse aides, patients, and family members).

Workshop on Electron-Cloud Simulations for Proton and Positron Beams (ECLOUD'02) organized by the SL Accelerator Physics Group at CERN.

CERN Multimedia

Patrice Loïez

2002-01-01

This workshop was organized by the SL Accelerator Physics group at CERN from 15 to 18 April 2002. More than 60 participants from 17 institutes reflect the great worldwide interest in the electron-cloud phenomenon, which presently limits the performance of several storage rings and has become a concern for the LHC.

Age-hardening susceptibility of high-Cr ODS ferritic steels and SUS430 ferritic steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Dongsheng, E-mail: chen.dongsheng85@gmail.com [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko; Han, Wentuo; Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2015-10-15

Highlights: • The role of oxide particles in α/α′ phase decomposition behavior; microstructure of phase decomposition observed by TEM. • The characteristics of ductility loss caused by age-hardening. • Correlation of phase decomposition and age-hardening explained by dispersion strengthened models. • Age-hardening susceptibility of ODS steels and SUS430 steel. - Abstract: The effect of aging on high-Cr ferritic steels was investigated with focusing on the role of oxide particles in α/α′ phase decomposition behavior. 12Cr-oxide dispersion strengthened (ODS) steel, 15Cr-ODS steel and commercial SUS430 steel were isothermally aged at 475 °C for up to 10,000 h. Thermal aging caused a larger hardening in SUS430 than 15Cr-ODS, while 12Cr-ODS showed almost no hardening. A characteristic of the ODS steels is that the hardening was not accompanied by the significant loss of ductility that was observed in SUS430 steel. After aging for 2000 h, SUS430 steel shows a larger ductile–brittle transition temperature (DBTT) shift than 15Cr-ODS steel, which suggests that the age-hardening susceptibility is lower in 15Cr-ODS steel than in conventional SUS430 steel. Thermal aging leaded to a large number of Cr-rich α′ precipitates, which were confirmed by transmission electron microscopy (TEM). Correlation of age-hardening and phase decomposition was interpreted by Orowan type strengthening model. Results indicate that oxide particles cannot only suppress ductility loss, but also may influence α/α′ phase decomposition kinetics.

Preliminary microstructural characterization by transmission electron microscopy of 14 MeV neutron irradiated type 316 stainless steel

International Nuclear Information System (INIS)

Echer, C.J.

1977-01-01

Substantial changes in the mechanical properties of 316 stainless steel were observed after neutron irradiation (phi/sub t/ = 2.3 x 10 21 n/m 2 and E = 14 MeV) at 25 0 C. Comparison of microstructures of the unirradiated and neutron irradiated materials were evaluated using transmission electron microscopy. Evidence of small defect clusters in the irradiated material was found. These findings are consistent with other investigators also evaluating low dose irradiations

Characterization of D2 tool steel friction surfaced coatings over low carbon steel

International Nuclear Information System (INIS)

Sekharbabu, R.; Rafi, H. Khalid; Rao, K. Prasad

2013-01-01

Highlights: • Solid state coating by friction surfacing method. • D2 tool steel is coated over relatively softer low carbon steel. • Defect free interface between tool steel coating and low carbon steel substrate. • D2 coatings exhibited higher hardness and good wear resistance. • Highly refined martensitic microstructure in the coating. - Abstract: In this work D2 tool steel coating is produced over a low carbon steel substrate using friction surfacing process. The process parameters are optimized to get a defect free coating. Microstructural characterization is carried out using optical microscopy, scanning electron microscopy and X-ray diffraction. Infrared thermography is used to measure the thermal profile during friction surfacing of D2 steel. Wear performance of the coating is studied using Pin-on-Disk wear tests. A lower rotational speed of the consumable rod and higher translational speed of the substrate is found to result in thinner coatings. Friction surfaced D2 steel coating showed fine-grained martensitic microstructure compared to the as-received consumable rod which showed predominantly ferrite microstructure. Refinement of carbides in the coating is observed due to the stirring action of the process. The infrared thermography studies showed the peak temperature attained by the D2 coating to be about 1200 °C. The combined effect of martensitic microstructure and refined carbides resulted in higher hardness and wear resistance of the coating

Self-Consistant Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Secondo, R.; Venturini, M.; Fox, J.D.; Rivetta, C.H.

2010-01-01

The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Comparisons to selected experimental data are also given. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons. Comparisons to experimental data are also given.

Deformation mechanisms in austenitic TRIP/TWIP steels at room and elevated temperature investigated by acoustic emission and scanning electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Linderov, M. [Laboratory of Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation); Segel, C.; Weidner, A.; Biermann, H. [Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, 09599 Freiberg (Germany); Vinogradov, A., E-mail: vinogradov@tltsu.ru [Laboratory of Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation)

2014-03-01

The modern austenitic stainless TRIP/TWIP steels have an outstanding combination of strength and ductility, depending on their chemical composition and loading conditions. A critical factor, which strongly affects all deformation-induced processes in metastable austenitic steels, is the temperature. To get a better insight into the effect of temperature on the deformation kinetics and transformation processes in high-alloy CrMnNi TRIP/TWIP steels with different austenite stability due to a varied content of Ni (3, 6 and 9 wt%), an acoustic emission (AE) technique was used during uniaxial tension at two different temperatures – ambient and 373 K. The in-situ AE results were paired with detailed SEM investigations using the electron backscattered diffraction (EBSD) technique to identify the deformation-induced phase transformations and mechnical twinning. The cluster analysis of the AE signals has revealed an excellent correlation of AE features with synergistic complexity of deformation mechanisms involved in various combinations: dislocation glide, stacking faults, martensitic phase transformation and twinning.

Plasma cloud expansion in the ionosphere: Three-dimensional simulation

International Nuclear Information System (INIS)

Ma, T.Z.; Schunk, R.W.

1991-01-01

A three-dimensional time-dependent model was developed to study the characteristics of a plasma cloud expansion in the ionosphere. The electrostatic potential is solved in three dimensions taking into account the large parallel-to-perpendicular conductivity ratio. Three sample simulations are presented: a plasma expansion of a nearly spherical 1 km Ba + cloud, both with and without a background neutral wind, and a long thin Ba + cloudlet. With or without the neutral wind the effective potential, which is different from the electrostatic potential if the electron temperature is included, is constant along the magnetic field for typical cloud sizes. The expanding plasma clouds become elongated in the magnetic field direction. The released Ba + ions push the background O + ions away along the magnetic field as they expand. Consequently, a hole develops in the background O + distribution at the cloud location and on the two sides of the cloud O + bumps form. The entire three-dimensional structure, composed of the plasma cloud and the background plasma embedded in the cloud, slowly rotates about the magnetic field, with the ions and electrons rotating in opposite directions. The cloud configuration takes the shape of a rotating ellipsoid with a major axis that expands with time. Perpendicular to the magnetic field, in the absence of the neutral wind the motion is insignificant compared to the parallel motion. With a neutral wind the motion along the magnetic field and the rotational motion are qualitatively unchanged, but the cloud and the perturbed background structure move in the direction of the wind, with a speed less than the wind speed. Perpendicular to the magnetic field the deformation of the cloud indiced by the wind is characterized by steepening of the backside

Surface modification of hydroturbine steel using friction stir processing

Science.gov (United States)

Grewal, H. S.; Arora, H. S.; Singh, H.; Agrawal, A.

2013-03-01

Friction stir processing (FSP) has proved to be a viable tool for enhancing the mechanical properties of materials, however, the major focus has been upon improving the bulk properties of light metals and their alloys. Hydroturbines are susceptible to damage owing to slurry and cavitation erosion. In this study, FSP of a commonly employed hydroturbine steel, 13Cr4Ni was undertaken. Microstructural characterization of the processed steel was conducted using optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and electron back scatter diffraction (EBSD) techniques. Mechanical characterization of the steel was undertaken in terms of microhardness and resistance to cavitation erosion (CE). FSP resulted in the refinement of the microstructure with reduction in grain size by a factor of 10. EBSD results confirmed the existence of submicron and ultrafine grained microstructure. The microhardness of the steel was found to enhance by 2.6 times after processing. The processed steel also showed 2.4 times higher resistance against cavitation erosion in comparison to unprocessed steel. The primary erosion mechanism for both the steels was identical in nature, with plastic deformation responsible for the loss of material.

Morphological and microstructural studies on aluminizing coating of carbon steel

Energy Technology Data Exchange (ETDEWEB)

Samsu, Zaifol; Othman, Norinsan Kamil; Daud, Abd Razak; Hussein, Hishammuddin [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

2013-11-27

Hot dip aluminizing is one of the most effective methods of surface protection for steels and is gradually gaining popularity. The morphology and microstructure of an inter-metallic layer form on the surface of low carbon steel by hot dip aluminization treatment had been studied in detail. This effect has been investigated using optical and scanning electron microscopy, and X-ray diffraction. The result shows that the reaction between the steel and the molten aluminium leads to the formation of Fe–Al inter-metallic compounds on the steel surface. X-ray diffraction and electron microscopic studies showed that a two layer coating was formed consisting of an external Al layer and a (Fe{sub 2}Al{sub 5}) inter metallic on top of the substrate after hot dip aluminizing process. The inter-metallic layer is ‘thick’ and exhibits a finger-like growth into the steel. Microhardness testing shown that the intermetallic layer has high hardness followed by steel substrate and the lowest hardness was Al layer.

Structural, electronic and photovoltaic characterization of multiwalled carbon nanotubes grown directly on stainless steel

Directory of Open Access Journals (Sweden)

Luca Camilli

2012-05-01

Full Text Available We have taken advantage of the native surface roughness and the iron content of AISI-316 stainless steel to grow multiwalled carbon nanotubes (MWCNTs by chemical vapour deposition without the addition of an external catalyst. The structural and electronic properties of the synthesized carbon nanostructures have been investigated by a range of electron microscopy and spectroscopy techniques. The results show the good quality and the high graphitization degree of the synthesized MWCNTs. Through energy-loss spectroscopy we found that the electronic properties of these nanostructures are markedly different from those of highly oriented pyrolytic graphite (HOPG. Notably, a broadening of the π-plasmon peak in the case of MWCNTs is evident. In addition, a photocurrent was measured when MWCNTs were airbrushed onto a silicon substrate. External quantum efficiency (EQE and photocurrent values were reported both in planar and in top-down geometry of the device. Marked differences in the line shapes and intensities were found for the two configurations, suggesting that two different mechanisms of photocurrent generation and charge collection are in operation. From this comparison, we are able to conclude that the silicon substrate plays an important role in the production of electron–hole pairs.

Cloud Infrastructure & Applications - CloudIA

Science.gov (United States)

Sulistio, Anthony; Reich, Christoph; Doelitzscher, Frank

The idea behind Cloud Computing is to deliver Infrastructure-as-a-Services and Software-as-a-Service over the Internet on an easy pay-per-use business model. To harness the potentials of Cloud Computing for e-Learning and research purposes, and to small- and medium-sized enterprises, the Hochschule Furtwangen University establishes a new project, called Cloud Infrastructure & Applications (CloudIA). The CloudIA project is a market-oriented cloud infrastructure that leverages different virtualization technologies, by supporting Service-Level Agreements for various service offerings. This paper describes the CloudIA project in details and mentions our early experiences in building a private cloud using an existing infrastructure.

An investigation of fusion zone microstructures in electron beam welding of copper-stainless steel

International Nuclear Information System (INIS)

Magnabosco, I.; Ferro, P.; Bonollo, F.; Arnberg, L.

2006-01-01

The article presents a study of three different welded joints produced by electron beam welding dissimilar materials. The junctions were obtained between copper plates and three different austenitic stainless steel plates. Different welding parameters were used according to the different thicknesses of the samples. Morphological, microstructural and mechanical (micro-hardness test) analyses of the weld bead were carried out. The results showed complex heterogeneous fusion zone microstructures characterized both by rapid cooling and poor mixing of the materials which contain main elements which are mutually insoluble. Some defects such as porosity and microfissures were also found. They are mainly due to the process and geometry parameters

Manifestations of electric currents in interstellar molecular clouds

International Nuclear Information System (INIS)

Carlqvist, P.; Gahm, G.F.

1991-12-01

We draw the attention to filamentary structures in molecular clouds and point out the existence of subfilaments of sinusoidal shape and also of helix-like structures. For two dark clouds, the Lynds 204 complex and the Sandqvist 187-188 complex (The Norma 'sword') we make a detailed study of such shapes and in addition we find the possible existence of helices wound around the main filaments. All these features are highly reminiscent of morphologies encountered in solar ascending prominences and in experiments in plasma physics and suggest the existence of electric currents and magnetic fields in these clouds. On the basis of a generalization of the Bennett pinch model, we derive the magnitudes of the currents expected to flow in the filaments. Values of column densities, magnetic field strengths, and direction of the fields are derived from observations. Magnetic fields with both toroidal and axial components are considered. This study shows that axial currents of the order of a few times 10 13 A are necessary for the clouds to be in equilibrium. The corresponding mean current densities are very small and even at the very low values of the fractional abundance of electrons encountered in these clouds, the mean electron velocities are of the order of 10 -2 -10 -5 m s -1 , much lower than the thermal velocities in the clouds. We suggest that helical structures may evolve as a result of various instabilities in the pinched clouds. We also call the attention to the kink intability in connection with the sinusoidal shapes. The existence of electromagnetically controlled features in the interstellar clouds can be tested by further observations. (au)

Comparison between magnetic force microscopy and electron back-scatter diffraction for ferrite quantification in type 321 stainless steel

Energy Technology Data Exchange (ETDEWEB)

Warren, A.D., E-mail: Xander.Warren@bristol.ac.uk [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Harniman, R.L. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Collins, A.M. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Bristol Centre for Functional Nanomaterials, Nanoscience and Quantum Information Centre, University of Bristol, Bristol BS8 1FD (United Kingdom); Davis, S.A. [School of Chemistry, University of Bristol, Bristol BS8 1 TS (United Kingdom); Younes, C.M. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Flewitt, P.E.J. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); School of Physics, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom); Scott, T.B. [Interface Analysis Centre, HH Wills Laboratory, University of Bristol, Bristol BS8 1FD (United Kingdom)

2015-01-15

Several analytical techniques that are currently available can be used to determine the spatial distribution and amount of austenite, ferrite and precipitate phases in steels. The application of magnetic force microscopy, in particular, to study the local microstructure of stainless steels is beneficial due to the selectivity of this technique for detection of ferromagnetic phases. In the comparison of Magnetic Force Microscopy and Electron Back-Scatter Diffraction for the morphological mapping and quantification of ferrite, the degree of sub-surface measurement has been found to be critical. Through the use of surface shielding, it has been possible to show that Magnetic Force Microscopy has a measurement depth of 105–140 nm. A comparison of the two techniques together with the depth of measurement capabilities are discussed. - Highlights: • MFM used to map distribution and quantify ferrite in type 321 stainless steels. • MFM results compared with EBSD for same region, showing good spatial correlation. • MFM gives higher area fraction of ferrite than EBSD due to sub-surface measurement. • From controlled experiments MFM depth sensitivity measured from 105 to 140 nm. • A correction factor to calculate area fraction from MFM data is estimated.

Reduction of secondary electron yield for E-cloud mitigation by laser ablation surface engineering

Energy Technology Data Exchange (ETDEWEB)

Valizadeh, R., E-mail: reza.valizadeh@stfc.ac.uk [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Malyshev, O.B. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Wang, S. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sian, T. [ASTeC, STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); The Photon Science Institute, The University of Manchester, Manchester M13 9PL (United Kingdom); Cropper, M.D. [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Sykes, N. [Micronanics Ltd., Didcot, Oxon OX11 0QX (United Kingdom)

2017-05-15

Highlights: • SEY below 1 can be achieved with Laser ablation surface engineering. • SEY <1 surface can be produced with different types of nanosecond lasers. • Both microstructure (groves) and nano-structures are playing a role in reducing SEY. - Abstract: Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators. In our previous publications, a low SEY < 0.9 for as-received metal surfaces modified by a nanosecond pulsed laser was reported. In this paper, the SEY of laser-treated blackened copper has been investigated as a function of different laser irradiation parameters. We explore and study the influence of micro- and nano-structures induced by laser surface treatment in air of copper samples as a function of various laser irradiation parameters such as peak power, laser wavelength (λ = 355 nm and 1064 nm), number of pulses per point (scan speed and repetition rate) and fluence, on the SEY. The surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) which revealed that heating resulted in diffusion of oxygen into the bulk and induced the transformation of CuO to sub-stoichiometric oxide. The surface topography was examined with high resolution scanning electron microscopy (HRSEM) which showed that the laser-treated surfaces are dominated by microstructure grooves and nanostructure features.

Simulation of a Feedback System for the Attenuation of e-Cloud Driven Instability

International Nuclear Information System (INIS)

Vay, J.-L.; Furman, M.A.; Fox, J.; Rivetta, C.; de Maria, R.; Rumolo, G.

2009-01-01

Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. Recently, it has been proposed to use feedback systems operating at high frequency (in the GHz range) to damp single-bunch transverse coherent oscillations that may otherwise be amplified during the interaction of the beam with ambient electron clouds. We have used the simulation package WARP-POSINST and the code Headtail to study the growth rate and frequency patterns in space-time of the electron cloud driven beam breakup instability in the CERN SPS accelerator with, or without, an idealized feedback model for damping the instability.

Cosmic rays, clouds and climate

Energy Technology Data Exchange (ETDEWEB)

Svensmark, Henrik [Danish Space Research Institute, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2007-07-01

Changes in the intensity of galactic cosmic rays seems alter the Earth's cloudiness. A recent experiment has shown how electrons liberated by cosmic rays assist in making aerosols, the building blocks of cloud condensation nuclei, while anomalous climatic trends in Antarctica confirm the role of clouds in helping to drive climate change. Variations in the cosmic-ray influx due to solar magnetic activity account well for climatic fluctuations on decadal, centennial and millennial timescales. Over longer intervals, the changing galactic environment of the Solar System has had dramatic consequences, including Snowball Earth episodes.

Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision

OpenAIRE

Inoue, Tsuyoshi; Fukui, Yasuo

2013-01-01

Recent observations of molecular clouds around rich massive star clusters including NGC3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by the cloud-cloud collision. We find that the massive mol...

LS1 Report: the clouds are lifting

CERN Multimedia

Anaïs Schaeffer

2014-01-01

To combat the problem of electron clouds, which perturbate the environment of the particle beams in our accelerators, the Vacuum team have turned to amorphous carbon. This material is being applied to the interior of 16 magnets in the SPS during LS1 and will help prevent the formation of the secondary particles which are responsible for these clouds.   This photo shows the familiar coils of an SPS dipole magnet in brown. The vacuum chamber is the metallic rectangular part in the centre. The small wheeled device you can see in the vacuum chamber carries the hollow cathodes  along the length of the chamber. When a particle beam circulates at high energy in a vacuum chamber, it unavoidably generates secondary particles. These include electrons produced by the ionisation of residual molecules in the vacuum or indirectly generated by synchrotron radiation. When these electrons hit the surface of the vacuum chamber, they produce other electrons which, through an avalanche-like process, re...

High-performance scientific computing in the cloud

Science.gov (United States)

Jorissen, Kevin; Vila, Fernando; Rehr, John

2011-03-01

Cloud computing has the potential to open up high-performance computational science to a much broader class of researchers, owing to its ability to provide on-demand, virtualized computational resources. However, before such approaches can become commonplace, user-friendly tools must be developed that hide the unfamiliar cloud environment and streamline the management of cloud resources for many scientific applications. We have recently shown that high-performance cloud computing is feasible for parallelized x-ray spectroscopy calculations. We now present benchmark results for a wider selection of scientific applications focusing on electronic structure and spectroscopic simulation software in condensed matter physics. These applications are driven by an improved portable interface that can manage virtual clusters and run various applications in the cloud. We also describe a next generation of cluster tools, aimed at improved performance and a more robust cluster deployment. Supported by NSF grant OCI-1048052.

Helium and its effects on the creep-fatigue behaviour of electron beam welds in the steel AISI-316-L

International Nuclear Information System (INIS)

Paulus, M.

1992-12-01

Within the scope of R and D work for materials development for the NET fusion experiment (Next European Torus) and the International Thermonuclear Experimental Reactor (ITER), the task reported was to examine electron beam welds in the austenitic stainless steel AISI 316 L (NET reference material) for their fatigue behaviour under creep load, and the effects of helium implantation on there mechanical properties. (orig.) [de

Negative chlorine ion chemistry in the upper stratosphere and its application to an artificially created dense electron cloud

Directory of Open Access Journals (Sweden)

S. S. Prasad

1995-03-01

Full Text Available This paper discusses new potential reactions of chlorine-bearing anions (negative ions in the upper stratosphere. These reactions are then applied to the negative-ion chemistry following the injection of an electron cloud of very high density, of the order of 106-107 e- cm-3, in the 40-45-km region. The idea is to evaluate the recently proposed scheme to mitigate ozone depletion by converting the reactive chlorine atoms at these altitudes into Cl- ions which are unreactive towards ozone, i.e., electron scavenging of Cl. We find that the previously neglected photodetachment from Cl- is fast. For an overhead sun, this process may have a rate coefficient of 0.08 s-1 when multiple scattering is included. The rate could be even higher, depending on the ground albedo. Switching reaction between Cl-·H2O and HCl might lead to the formation of Cl-·HCl anion. Possible reactions of Cl-·H2O and Cl-·HCl with O atoms could produce ClO- and Cl-2. The production of ClO- in this manner is significant because Cl- having a high photodetachment rate constant would be regenerated in the very likely reactions of ClO- with O. When these possibilities are considered, then it is found that the chlorine anions may not be the major ions inside the electron cloud due to the rapid photodetachment from Cl-. Furthermore, in such a cloud, there may be the hazard that the Cl--Cl-·H2O-ClO--Cl- cycle amounts to catalytic destruction of two O atoms. Thus, the scheme could be risky if practised in the altitude region where atomic oxygen is an important constituent. Similar conclusions apply even if the ClO- species forms ClO-3 by three-body association with O2, instead of reacting with O. It must be emphasized that the present study is speculative at this time, because none of the relevant reactions have been investigated in the laboratory as yet. Nevertheless, it is very safe to say that the scheme of ozone preservation by electron scavenging of the upper stratospheric Cl is

Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

OpenAIRE

Y. Liu; W. Wu; M. P. Jensen; T. Toto

2011-01-01

This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

Influence of temperature, chloride ions and chromium element on the electronic property of passive film formed on carbon steel in bicarbonate/carbonate buffer solution

Energy Technology Data Exchange (ETDEWEB)

Li, D.G. [School of Materials Science and Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Tubular Goods Research Center of CNPC, Xi' an 710065 (China)], E-mail: dangguoli78@yahoo.com.cn; Feng, Y.R.; Bai, Z.Q. [Tubular Goods Research Center of CNPC, Xi' an 710065 (China); Zhu, J.W.; Zheng, M.S. [School of Materials Science and Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

2007-11-01

The influences of temperature, chloride ions and chromium element on the electronic property of passive film formed on carbon steel in NaHCO{sub 3}/Na{sub 2}CO{sub 3} buffer solution are investigated by capacitance measurement and electrochemical impedance spectroscopy (EIS). The results show that the passive film appears n-type semiconductive character; with increasing the solution temperature, the addition of chromium into carbon steel and increasing the concentration of chloride ions, the slopes of Mott-Schottky plots decrease, which indicates the increment of the defect density in the passive film. EIS results show that the transfer impedance R{sub 1} and the diffusion impedance W decrease with increasing the solution temperature, with the addition of chromium into carbon steel and with increasing the chloride ions concentration. It can be concluded that the corrosion protection effect of passive film on the substrate decreases with increasing the solution temperature, adding chromium into carbon steel and increasing chloride ions concentration.

Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

OpenAIRE

Dumas, Claire; Basséguy, Régine; Bergel, Alain

2008-01-01

Stainless steel and graphite electrodes were individually addressed and polarized at−0.60V vs. Ag/AgCl in reactors filled with a growth medium that contained 25mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75Am−2 for graphite and 20.5Am−2 for stainless steel. Cyclic voltamm...

Optimum conditions for aging of stainless maraging steels

International Nuclear Information System (INIS)

Mironenko, P.A.; Krasnikova, S.I.; Drobot, A.V.

1980-01-01

Aging kinetics of two 0Kh11N10M2T type steels in which 3 % Mo (steel 1), and 3 % Mo and 11 % Co (steel 2) had been additionally introduced instead of titanium were investigated. Electron microscopy and X-ray methods were used. It was ascertained that the process of steel aging proceeded in 3 stages. Steel 2 was hardened more intensively during the aging, had a higher degree of hardness and strength after the aging, weakened more slowly if overaged than steel 1. The intermetallide hcp-phase Fe 2 Mo was the hardening phase on steels extended aging. Optimum combination of impact strength and strength was was achieved using two-stage aging: the first stage - maximum strength aging was achieved, the second stage - aging at minimum temperatures of two-phase α+γ region

Simultaneous observations of solar MeV particles in a magnetic cloud and in the earth's northern tail lobe - Implications for the global field line topology of magnetic clouds and for the entry of solar particles into the magnetosphere during cloud passage

Science.gov (United States)

Farrugia, C. J.; Richardson, I. G.; Burlaga, L. F.; Lepping, R. P.; Osherovich, V. A.

1993-01-01

Simultaneous ISEE 3 and IMP 8 spacecraft observations of magnetic fields and flow anisotropies of solar energetic protons and electrons during the passage of an interplanetary magnetic cloud show various particle signature differences at the two spacecraft. These differences are interpretable in terms of the magnetic line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of the magnetic clouds and of the earth. These observations are consistent with a magnetic cloud model in which these mesoscale configurations are curved magnetic flux ropes attached at both ends to the sun's surface, extending out to 1 AU.

The dynamics of low-β plasma clouds as simulated by a three-dimensional, electromagnetic particle code

International Nuclear Information System (INIS)

Neubert, T.; Miller, R.H.; Buneman, O.; Nishikawa, K.I.

1992-01-01

The dynamics of low-β plasma clouds moving perpendicular to an ambient magnetic field in vacuum and in a background plasma is simulated by means of a three-dimensional, electromagnetic, and relativistic particle simulation code. The simulations show the formation of the space charge sheaths at the sides of the cloud with the associated polarization electric field which facilitate the cross-field propagation, as well as the sheaths at the front and rear end of the cloud caused by the larger ion Larmor radius, which allows ions to move ahead and lag behind the electrons as they gyrate. Results on the cloud dynamics and electromagnetic radiation include the following: (1) In a background plasma, electron and ion sheaths expand along the magnetic field at the same rate, whereas in vacuum the electron sheath expands much faster than the ion sheath. (2) Sheath electrons are accelerated up to relativistic energies. This result indicates that artificial plasma clouds released in the ionosphere or magnetosphere may generate optical emissions (aurora) as energetic sheath electrons scatter in the upper atmosphere. (3) The expansion of the electron sheaths is analogous to the ejection of high-intensity electron beams from spacecraft. (4) Second-order and higher-order sheaths are formed which extend out into the ambient plasma. (5) Formation of the sheaths and the polarization field reduces the forward momentum of the cloud. (6) The coherent component of the particle gyromotion is damped in time as the particles establish a forward directed drift velocity. (7) The coherent particle gyrations generate electromagnetic radiation

Status report on the 'Merging' of the Electron-Cloud Code POSINST with the 3-D Accelerator PIC CODE WARP

Energy Technology Data Exchange (ETDEWEB)

Vay, J.-L.; Furman, M.A.; Azevedo, A.W.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Stoltz, P.H.

2004-04-19

We have integrated the electron-cloud code POSINST [1] with WARP [2]--a 3-D parallel Particle-In-Cell accelerator code developed for Heavy Ion Inertial Fusion--so that the two can interoperate. Both codes are run in the same process, communicate through a Python interpreter (already used in WARP), and share certain key arrays (so far, particle positions and velocities). Currently, POSINST provides primary and secondary sources of electrons, beam bunch kicks, a particle mover, and diagnostics. WARP provides the field solvers and diagnostics. Secondary emission routines are provided by the Tech-X package CMEE.

Interaction of plasma cloud with external electric field in lower ionosphere

Directory of Open Access Journals (Sweden)

Y. S. Dimant

2010-03-01

Full Text Available In the auroral lower-E and upper-D region of the ionosphere, plasma clouds, such as sporadic-E layers and meteor plasma trails, occur daily. Large-scale electric fields, created by the magnetospheric dynamo, will polarize these highly conducting clouds, redistributing the electrostatic potential and generating anisotropic currents both within and around the cloud. Using a simplified model of the cloud and the background ionosphere, we develop the first self-consistent three-dimensional analytical theory of these phenomena. For dense clouds, this theory predicts highly amplified electric fields around the cloud, along with strong currents collected from the ionosphere and circulated through the cloud. This has implications for the generation of plasma instabilities, electron heating, and global MHD modeling of magnetosphere-ionosphere coupling via modifications of conductances induced by sporadic-E clouds.

Cloud screening Coastal Zone Color Scanner images using channel 5

Science.gov (United States)

Eckstein, B. A.; Simpson, J. J.

1991-01-01

Clouds are removed from Coastal Zone Color Scanner (CZCS) data using channel 5. Instrumentation problems require pre-processing of channel 5 before an intelligent cloud-screening algorithm can be used. For example, at intervals of about 16 lines, the sensor records anomalously low radiances. Moreover, the calibration equation yields negative radiances when the sensor records zero counts, and pixels corrupted by electronic overshoot must also be excluded. The remaining pixels may then be used in conjunction with the procedure of Simpson and Humphrey to determine the CZCS cloud mask. These results plus in situ observations of phytoplankton pigment concentration show that pre-processing and proper cloud-screening of CZCS data are necessary for accurate satellite-derived pigment concentrations. This is especially true in the coastal margins, where pigment content is high and image distortion associated with electronic overshoot is also present. The pre-processing algorithm is critical to obtaining accurate global estimates of pigment from spacecraft data.

A study of intergranular corrosion of austenitic stainless steel by electrochemical potentiodynamic reactivation, electron back-scattering diffraction and cellular automaton

Energy Technology Data Exchange (ETDEWEB)

Yu Xiaofei [Department of Chemistry, Shandong University, Jinan 250100 (China); Chen Shenhao [Department of Chemistry, Shandong University, Jinan 250100 (China); State Key Laboratory for Corrosion and Protection, Shenyang 110016 (China)], E-mail: shchen@sdu.edu.cn; Liu Ying; Ren Fengfeng [Department of Chemistry, Shandong University, Jinan 250100 (China)

2010-06-15

The impact of solution and sensitization treatments on the intergranular corrosion (IGC) of austenitic stainless steel (316) was studied by electrochemical potentiodynamic reactivation (EPR) test, and the results showed the degree of sensitization (DOS) decreased as solution treatment temperature and time went up, but it increased as sensitization temperature prolonged. Factors that affected IGC were investigated by field emission scanning electron microscope (FE-SEM) and electron back-scattering diffraction (EBSD). Furthermore, the precipitation evolution of Cr-rich carbides and the distribution of chromium concentration were simulated by cellular automaton (CA), clearly showing the effects of solution and sensitization treatments on IGC.

Surface electrical properties of stainless steel fibres: An AFM-based study

International Nuclear Information System (INIS)

Yin, Jun; D’Haese, Cécile; Nysten, Bernard

2015-01-01

Highlights: • Surface electrical conductivity of stainless steel fibre is measured and mapped by CS-AFM. • Surface potential of stainless steel fibre is measured and mapped by KPFM. • Surface electronic properties are governed by the chromium oxide passivation layer. • Electron tunnelling through the passivation layer is the dominant mechanisms for conduction. - Abstract: Atomic force microscopy (AFM) electrical modes were used to study the surface electrical properties of stainless steel fibres. The surface electrical conductivity was studied by current sensing AFM and I–V spectroscopy. Kelvin probe force microscopy was used to measure the surface contact potential. The oxide film, known as passivation layer, covering the fibre surface gives rise to the observation of an apparently semiconducting behaviour. The passivation layer generally exhibits a p-type semiconducting behaviour, which is attributed to the predominant formation of chromium oxide on the surface of the stainless steel fibres. At the nanoscale, different behaviours are observed from points to points, which may be attributed to local variations of the chemical composition and/or thickness of the passivation layer. I–V curves are well fitted with an electron tunnelling model, indicating that electron tunnelling may be the predominant mechanism for electron transport

Application of electron beam welding to large size pressure vessels made of thick low alloy steel

International Nuclear Information System (INIS)

Kuri, S.; Yamamoto, M.; Aoki, S.; Kimura, M.; Nayama, M.; Takano, G.

1993-01-01

The authors describe the results of studies for application of the electron beam welding to the large size pressure vessels made of thick low alloy steel (ASME A533 Gr.B cl.2 and A533 Gr.A cl.1). Two major problems for applying the EBW, the poor toughness of weld metal and the equipment to weld huge pressure vessels are focused on. For the first problem, the effects of Ni content of weld metal, welding conditions and post weld heat treatment are investigated. For the second problem, an applicability of the local vacuum EBW to a large size pressure vessel made of thick plate is qualified by the construction of a 120 mm thick, 2350 mm outside diameter cylindrical model. The model was electron beam welded using local vacuum chamber and the performance of the weld joint is investigated. Based on these results, the electron beam welding has been applied to the production of a steam generator for a PWR. (author). 3 refs., 10 figs., 4 tabs

Microstructural characterisation and corrosion performance of old railway girder bridge steel and modern weathering structural steel

International Nuclear Information System (INIS)

Tewary, N.K.; Kundu, A.; Nandi, R.; Saha, J.K.; Ghosh, S.K.

2016-01-01

Highlights: • Microstructure and corrosion performance are compared for two structural steels. • Microstructure evolution shows primarily ferrite-pearlite in both the steels. • Steels show higher corrosion rate in 1% HCl solution than in 3.5% NaCl solution. • The corrosion products show the presence of oxide, hydroxide and oxy-hydroxides. • The corroded surface reveals morphologies like flowery, cotton balls and rosette. - Abstract: A comparison on microstructure and corrosion performance has been made between the two structural steels used in old railway girder bridge (Sample A) and modern grades of weathering structural steel (Sample B). The microstructures, viewed under optical microscope and scanning electron microscope (SEM), show mainly ferrite-pearlite phase constituents in both the steels, A and B. The phase fraction analysis shows higher amount of pearlite in steel A compared to that of steel B. The grain size of steel A is larger than that of steel B under identical processing condition. The immersion corrosion test in 3.5% NaCl shows that the corrosion rate of steel A increases with time, while the same for steel B decreases with time. On the other hand, corrosion test in 1% HCl shows that the corrosion rate of both steel A and B is higher as compared to that of NaCl which always decreases with time. The XRD analysis of corrosion products show the presence of many oxides, hydroxide and oxy-hydroxide like Lepidocrocite (γ-FeOOH), Goethite (α-FeOOH), Akaganeite (β-FeOOH), Magnetite (Fe_3O_4) and Maghemite (γ-Fe_2O_3) in both the steels. The SEM images of corroded surfaces reveal different morphologies like flowery, cotton balls and rosette etc. which indicate that the corrosion products primarily contain Lepidocrocite (γ-FeOOH), Goethite (α-FeOOH) and Akaganeite (β-FeOOH).

Achieving Payoffs from an Industry Cloud Ecosystem at BankID

DEFF Research Database (Denmark)

Eaton, Ben; Hallingby, Hanne Kristine; Nesse, Per-Jonny

2014-01-01

BankID is an industry cloud owned by Norwegian banks. It provides electronic identity, authentication and electronic signing capabilities for banking, merchant and government services. More than 60% of the population uses BankID services. As the broader ecosystem around BankID evolved, challenges......—arising from tensions between different parts of the ecosystem—had to be resolved. The four lessons learned from the BankID case will help others to build an industry cloud and establish a healthy ecosystem to service a broad user base....

Low-cycle fatigue behaviors of pre-hardening Hadfield steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Chen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Lv, Bo [College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Wang, Fei [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, Fucheng, E-mail: zfc@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004 (China)

2017-05-17

Low-cycle fatigue behaviors of the pre-hardening (PH) and the water-quenching (WQ) Hadfield steel were studied using optical microscopy, transmission electron microscopy, and electron backscatter diffraction technique. The effect of the PH treatment on low-cycle fatigue behavior of the Hadfield steel was analyzed through comparing the cyclic hardening/softening behaviors and the changing regulations of stress amplitude, internal stress, and effective stress at different total strain amplitudes. Results showed obvious differences in fatigue behaviors between the PH (with a cold rolling deformation degree of 40%) and the WQ Hadfield steels. Transient hardening followed by cyclic stability behavior occurred in the PH Hadfield steel under cyclic loading, whereas cyclic softening behavior was barely observed. The fatigue life of the PH Hadfield steel was higher than that of the WQ Hadfield steel at relatively low strain amplitudes, while a contrary result was obtained at relatively high strain amplitudes. At low strain amplitudes, the deformation twins induced in the PH Hadfield steel could enhance the multiplication and slip process of dislocations, which actually improved the deformation uniformity. The long-range motion of dislocations was intensified at high strain amplitudes. However, the dislocation motion was also blocked by twin boundaries. As a result, the interactions between dislocations and deformation twins enhanced, finally causing severe dislocation accumulation. These two effects of deformation twins on dislocation motion eventually resulted in different low-cycle fatigue behaviors of the PH Hadfield steel.

Volatility Spillover in Chinese Steel Markets

Science.gov (United States)

Fang, Wen

2018-03-01

This paper examines volatility spillover in Chinese steel markets by comparing spillover effects before and after steel futures market established and finds some interesting change. Volatility spillover method based on multi-GARCH model are proposed. The results show that there is significant proof for spillover effects from B2B electronic market to spot market, and two-way effects between futures and spot market. Market policy planners and practitioners could make decisions according to the master of spillovers. We also find that B2B e-market and futures market can both provide efficient protection against steel price volatility risk, B2B e-market offer a broad-based platform for trading steel commodities over time and space since e-market role in information flow process is dominant.

Secure system for personal finances on the cloud

OpenAIRE

Quintana i Vidal, Xavier

2015-01-01

Este documento contiene la memoria de la realización del Trabajo Final de Máster que tiene como objetivo la creación de un Cloud para el almacenamiento de forma segura de las facturas electrónicas. This document contains the memory of the accomplishment of the final Project, which aims to create a Cloud for secure storage of the electronic invoices. Aquest document conté la memòria de la realització del Treball Final de Màster que té com a objectiu la creació d'un Cloud per a l'emmagatz...

Cloud-Top Entrainment in Stratocumulus Clouds

Science.gov (United States)

Mellado, Juan Pedro

2017-01-01

Cloud entrainment, the mixing between cloudy and clear air at the boundary of clouds, constitutes one paradigm for the relevance of small scales in the Earth system: By regulating cloud lifetimes, meter- and submeter-scale processes at cloud boundaries can influence planetary-scale properties. Understanding cloud entrainment is difficult given the complexity and diversity of the associated phenomena, which include turbulence entrainment within a stratified medium, convective instabilities driven by radiative and evaporative cooling, shear instabilities, and cloud microphysics. Obtaining accurate data at the required small scales is also challenging, for both simulations and measurements. During the past few decades, however, high-resolution simulations and measurements have greatly advanced our understanding of the main mechanisms controlling cloud entrainment. This article reviews some of these advances, focusing on stratocumulus clouds, and indicates remaining challenges.

Cloud type comparisons of AIRS, CloudSat, and CALIPSO cloud height and amount

Directory of Open Access Journals (Sweden)

B. H. Kahn

2008-03-01

Full Text Available The precision of the two-layer cloud height fields derived from the Atmospheric Infrared Sounder (AIRS is explored and quantified for a five-day set of observations. Coincident profiles of vertical cloud structure by CloudSat, a 94 GHz profiling radar, and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO, are compared to AIRS for a wide range of cloud types. Bias and variability in cloud height differences are shown to have dependence on cloud type, height, and amount, as well as whether CloudSat or CALIPSO is used as the comparison standard. The CloudSat-AIRS biases and variability range from −4.3 to 0.5±1.2–3.6 km for all cloud types. Likewise, the CALIPSO-AIRS biases range from 0.6–3.0±1.2–3.6 km (−5.8 to −0.2±0.5–2.7 km for clouds ≥7 km (<7 km. The upper layer of AIRS has the greatest sensitivity to Altocumulus, Altostratus, Cirrus, Cumulonimbus, and Nimbostratus, whereas the lower layer has the greatest sensitivity to Cumulus and Stratocumulus. Although the bias and variability generally decrease with increasing cloud amount, the ability of AIRS to constrain cloud occurrence, height, and amount is demonstrated across all cloud types for many geophysical conditions. In particular, skill is demonstrated for thin Cirrus, as well as some Cumulus and Stratocumulus, cloud types infrared sounders typically struggle to quantify. Furthermore, some improvements in the AIRS Version 5 operational retrieval algorithm are demonstrated. However, limitations in AIRS cloud retrievals are also revealed, including the existence of spurious Cirrus near the tropopause and low cloud layers within Cumulonimbus and Nimbostratus clouds. Likely causes of spurious clouds are identified and the potential for further improvement is discussed.

Business diversification in blast furnace steel makers. Koro kakusha no takakuka no jokyo

Energy Technology Data Exchange (ETDEWEB)

1991-11-01

Scenarios are presented for the current business diversification and future business developments by the three Japanese blast furnace steel makers (Kawasaki Steel, Kobe Steel and Shin Nippon Steel). The conceptions for their advancement into the 2lst century are more or less similar. The business diversification commenced for Kawasaki Steel in 1985, Kobe Steel in 1989 and Shin Nippon Steel in 1987, all taking a pattern of tree-like development into related businesses starting from the basic industry. Their new businesses may be summarized generically as: electronics industry (LSI, silicon, electronic devices, information and communication); new material related business (ferrite, ceramics, metal powder, metal foils); chemical business (plastics, etc.); engineerings (architecture, urban andregional developments, etc.); and service business (system network development, lease business, real estate, leisure business, etc.). Endeavors are made also on full-scale entity into tertiary industries, and amenity field. M A and joint venture businesses are attempted in wide scale and positive manners also in overseas countries. 6 fige., 4 tads.

A comparison of shock-cloud and wind-cloud interactions: effect of increased cloud density contrast on cloud evolution

Science.gov (United States)

Goldsmith, K. J. A.; Pittard, J. M.

2018-05-01

The similarities, or otherwise, of a shock or wind interacting with a cloud of density contrast χ = 10 were explored in a previous paper. Here, we investigate such interactions with clouds of higher density contrast. We compare the adiabatic hydrodynamic interaction of a Mach 10 shock with a spherical cloud of χ = 103 with that of a cloud embedded in a wind with identical parameters to the post-shock flow. We find that initially there are only minor morphological differences between the shock-cloud and wind-cloud interactions, compared to when χ = 10. However, once the transmitted shock exits the cloud, the development of a turbulent wake and fragmentation of the cloud differs between the two simulations. On increasing the wind Mach number, we note the development of a thin, smooth tail of cloud material, which is then disrupted by the fragmentation of the cloud core and subsequent `mass-loading' of the flow. We find that the normalized cloud mixing time (tmix) is shorter at higher χ. However, a strong Mach number dependence on tmix and the normalized cloud drag time, t_{drag}^' }, is not observed. Mach-number-dependent values of tmix and t_{drag}^' } from comparable shock-cloud interactions converge towards the Mach-number-independent time-scales of the wind-cloud simulations. We find that high χ clouds can be accelerated up to 80-90 per cent of the wind velocity and travel large distances before being significantly mixed. However, complete mixing is not achieved in our simulations and at late times the flow remains perturbed.

Cloud Computing, Tieto Cloud Server Model

OpenAIRE

Suikkanen, Saara

2013-01-01

The purpose of this study is to find out what is cloud computing. To be able to make wise decisions when moving to cloud or considering it, companies need to understand what cloud is consists of. Which model suits best to they company, what should be taken into account before moving to cloud, what is the cloud broker role and also SWOT analysis of cloud? To be able to answer customer requirements and business demands, IT companies should develop and produce new service models. IT house T...

Depth distribution of martensite in xenon implanted stainless steels

International Nuclear Information System (INIS)

Johansen, A.; Johnson, E.; Sarholt-Kristensen, L.; Steenstrup, S.; Hayashi, N.; Sakamoto, I.

1989-01-01

The amount of stress-induced martensite and its distribution in depth in xenon implanted austenitic stainless steel poly- and single crystals have been measured by Rutherford backscattering and channeling analysis, depth selective conversion electron Moessbauer spectroscopy, cross-sectional transmission electron microscopy and x-ray diffraction analysis. In low nickel 17/7, 304 and 316 commercial stainless steels and in 17:13 single crystals the martensitic transformation starts at the surface and develops towards greater depth with increasing xenon fluence. The implanted layer is nearly completely transformed, and the interface between martensite and austenite is rather sharp and well defined. In high nickel 310 commercial stainless steel and 15:19 and 20:19 single crystals, on the other hand, only insignificant amounts of martensite are observed. (orig.)

Study on cementitious properties of steel slag

Directory of Open Access Journals (Sweden)

Zhu G.

2013-01-01

Full Text Available The converter steel slag chemical and mineral components in China’s main steel plants have been analysed in the present paper. The electronic microscope, energy spectrum analysis, X-ray diffraction analysis confirmed the main mineral compositions in the converter slag. Converter slag of different components were grounded to obtain a powder with specific surface area over 400m2/kg, making them to take place some part of the cement in the concrete as the admixture and carry out the standard tests. The results indicate that the converter slag can be used as cementitious materials for construction. Furthermore, physical mechanic and durability tests on the concrete that certain amount of cement be substituted by converter steel slag powder from different steel plants are carried out, the results show that the concrete with partial substitution of steel slag powder has the advantages of higher later period strength, better frost resistance, good wear resistance and lower hydration heat, etc. This study can be used as the technical basis for “Steel Slag Powder Used For Cement And Concrete”, “Steel Slag Portland Cement”, “Low Heat Portland Steel Slag Cement”, “Steel Slag Road Cement” in China, as well as a driving force to the works of steel slag utilization with high-value addition, circular economy, energy conservation and discharge reduction in the iron and steel industry.

Temperature uniformity in the CERN CLOUD chamber

Directory of Open Access Journals (Sweden)

A. Dias

2017-12-01

Full Text Available The CLOUD (Cosmics Leaving OUtdoor Droplets experiment at CERN (European Council for Nuclear Research investigates the nucleation and growth of aerosol particles under atmospheric conditions and their activation into cloud droplets. A key feature of the CLOUD experiment is precise control of the experimental parameters. Temperature uniformity and stability in the chamber are important since many of the processes under study are sensitive to temperature and also to contaminants that can be released from the stainless steel walls by upward temperature fluctuations. The air enclosed within the 26 m3 CLOUD chamber is equipped with several arrays (strings of high precision, fast-response thermometers to measure its temperature. Here we present a study of the air temperature uniformity inside the CLOUD chamber under various experimental conditions. Measurements were performed under calibration conditions and run conditions, which are distinguished by the flow rate of fresh air and trace gases entering the chamber at 20 and up to 210 L min−1, respectively. During steady-state calibration runs between −70 and +20 °C, the air temperature uniformity is better than ±0.06 °C in the radial direction and ±0.1 °C in the vertical direction. Larger non-uniformities are present during experimental runs, depending on the temperature control of the make-up air and trace gases (since some trace gases require elevated temperatures until injection into the chamber. The temperature stability is ±0.04 °C over periods of several hours during either calibration or steady-state run conditions. During rapid adiabatic expansions to activate cloud droplets and ice particles, the chamber walls are up to 10 °C warmer than the enclosed air. This results in temperature differences of ±1.5 °C in the vertical direction and ±1 °C in the horizontal direction, while the air returns to its equilibrium temperature with a time constant of about 200 s.

Nanoscale characterization of the evolution of the twin–matrix orientation in Fe–Mn–C twinning-induced plasticity steel by means of transmission electron microscopy orientation mapping

International Nuclear Information System (INIS)

Albou, A.; Galceran, M.; Renard, K.; Godet, S.; Jacques, P.J.

2013-01-01

The evolution of the orientation relationship between mechanical twins and the surrounding matrix with the degree of plastic deformation has been characterized at the nanoscale in twinning-induced plasticity steel. The recently developed automated crystal orientation mapping in transmission electron microscopy revealed that the ideal twin relationship is retained up to large levels of strain, while large orientation gradients are built up within the matrix. This particular evolution undoubtedly plays a role in the large work hardening rate of these steels.

Steel Protective Coating Based on Plasticized Epoxy Acrylate Formulation Cured by Electron Beam Irradiation

International Nuclear Information System (INIS)

Ibrahim, M.S.; Said, H.M.; Mohamed, I.M.; Mohamed, H.A.; Kandile, N.G.

2011-01-01

Electron beam (EB) was used to cure coatings based on epoxy acrylate oligomer (EA) and different plasticizers such as epoxidized soybean oil, glycerol and castor oil. The effect of irradiation doses (10, 25, 50 kGy) on the curing epoxy acrylate formulations containing plasticizers was studied. In the addition, the effect of the different plasticizers on the end use performance properties of epoxy acrylate coatings such as hardness, bending, adhesion, acid and alkali resistance tests were investigated. It was observed that the incorporation of castor oil in epoxy acrylate, diluted by 1,6 hexandiol diacrylate monomer (HD) with a ratio (EA 70%, HD 20%, castor oil 10%) under the dose 10 kGy improved the physical, chemical and mechanical properties of cured films than the other plasticizers. On the other hand, sunflower free fatty acids were epoxidized in-situ under well established conditions and then was subjected to react with aniline in sealed ampoules under inert atmosphere at 140 degree C. The produced adduct was added at different concentrations to epoxy acrylate coatings under certain EB irradiation dose and then evaluated as corrosion inhibitors for carbon steel surfaces in terms of weight loss measurements and corrosion resistance tests. It was observed that the formula containing 0.4 gm of aniline adduct / 100 gm epoxy acrylate resin gave the best corrosion protection for carbon steel

Negative chlorine ion chemistry in the upper stratosphere and its application to an artificially created dense electron cloud

Directory of Open Access Journals (Sweden)

S. S. Prasad

Full Text Available This paper discusses new potential reactions of chlorine-bearing anions (negative ions in the upper stratosphere. These reactions are then applied to the negative-ion chemistry following the injection of an electron cloud of very high density, of the order of 10^6-10⁷ e^- cm^-3, in the 40-45-km region. The idea is to evaluate the recently proposed scheme to mitigate ozone depletion by converting the reactive chlorine atoms at these altitudes into Cl^- ions which are unreactive towards ozone, i.e., electron scavenging of Cl. We find that the previously neglected photodetachment from Cl^- is fast. For an overhead sun, this process may have a rate coefficient of 0.08 s^-1 when multiple scattering is included. The rate could be even higher, depending on the ground albedo. Switching reaction between Cl^-·H₂O and HCl might lead to the formation of Cl^-·HCl anion. Possible reactions of Cl^-·H₂O and Cl^-·HCl with O atoms could produce ClO^- and Cl^-₂. The production of ClO^- in this manner is significant because Cl^- having a high photodetachment rate constant would be regenerated in the very likely reactions of ClO^- with O. When these possibilities are considered, then it is found that the chlorine anions may not be the major ions inside the electron cloud due to the rapid photodetachment from Cl^-. Furthermore, in such a cloud, there may be the hazard that the Cl^--Cl^-·H₂O-ClO^--Cl^- cycle amounts to catalytic destruction of two O atoms. Thus, the scheme could be risky if practised in the altitude region where atomic oxygen is an important constituent. Similar conclusions apply even if the ClO^- species forms ClO^-₃ by three-body association with O₂

Accelerated corrosion of stainless steel in thiocyanate-containing solutions

Energy Technology Data Exchange (ETDEWEB)

Pistorius, P Chris; Li, Wen

2012-09-19

It is known that reduced sulfur compounds (such as thiocyanate and thiosulfate) can accelerate active corrosion of austenitic stainless steel in acid solutions, but before we started this project the mechanism of acceleration was largely unclear. This work combined electrochemical measurements and analysis using scanning electron microscopy (SEM) and X-ray photo-electron spectroscopy (XPS), which provided a comprehensive understanding of the catalytic effect of reduced sulfur species on the active corrosion of stainless steel. Both the behavior of the pure elements and the steel were studied and the work focused on the interaction between the pure elements of the steel, which is the least understood area. Upon completion of this work, several aspects are now much clearer. The main results from this work can be summarized as follows: The presence of low concentrations (around 0.1 mM) of thiocyanate or tetrathionate in dilute sulfuric acid greatly accelerates the anodic dissolution of chromium and nickel, but has an even stronger effect on stainless steels (iron-chromium-nickel alloys). Electrochemical measurements and surface analyses are in agreement with the suggestion that accelerated dissolution really results from suppressed passivation. Even well below the passivation potential, the electrochemical signature of passivation is evident in the electrode impedance; the electrode impedance shows clearly that this pre-passivation is suppressed in the presence of thiocyanate. For the stainless steels, remarkable changes in the morphology of the corroded metal surface and in the surface concentration of chromium support the suggestion that pre-passivation of stainless steels is suppressed because dissolution of chromium is accelerated. Surface analysis confirmed that adsorbed sulfur / sulfide forms on the metal surfaces upon exposure to solutions containing thiocyanate or thiosulfate. For pure nickel, and steels containing nickel (and residual copper), bulk sulfide

Influence of titanium on the tempering structure of austenitic steels

International Nuclear Information System (INIS)

Ghuezaiel, M.J.

1985-10-01

The microstructure of titanium-stabilized and initially deformed (approximately 20%) austenitic stainless steels used in structures of fast neutrons reactors has been studied after one hour duration annealings (500 0 C) by X-ray diffraction, optical microscopy, microhardness and transmission electron microscopy. The studied alloys were either of industrial type CND 17-13 (0.23 to 0.45 wt% Ti) or pure steels (18% Cr, 14% Ni, 0 or 0.3 wt% Ti). During tempering, the pure steels presented some restauration before recristallization. In the industrial steels, only recristallization occurred, and this only in the most deformed steel. Precipitation does not occur in the titanium-free pure steel. In industrial steels, many intermetallic phases are formed when recristallization starts [fr

Cloud residues and interstitial aerosols from non-precipitating clouds over an industrial and urban area in northern China

Science.gov (United States)

Li, Weijun; Li, Peiren; Sun, Guode; Zhou, Shengzhen; Yuan, Qi; Wang, Wenxing

2011-05-01

Most studies of aerosol-cloud interactions have been conducted in remote locations; few have investigated the characterization of cloud condensation nuclei (CCN) over highly polluted urban and industrial areas. The present work, based on samples collected at Mt. Tai, a site in northern China affected by nearby urban and industrial air pollutant emissions, illuminates CCN properties in a polluted atmosphere. High-resolution transmission electron microscopy (TEM) was used to obtain the size, composition, and mixing state of individual cloud residues and interstitial aerosols. Most of the cloud residues displayed distinct rims which were found to consist of soluble organic matter (OM). Nearly all (91.7%) cloud residues were attributed to sulfate-related salts (the remainder was mostly coarse crustal dust particles with nitrate coatings). Half the salt particles were internally mixed with two or more refractory particles (e.g., soot, fly ash, crustal dust, CaSO 4, and OM). A comparison between cloud residues and interstitial particles shows that the former contained more salts and were of larger particle size than the latter. In addition, a somewhat high number scavenging ratio of 0.54 was observed during cloud formation. Therefore, the mixtures of salts with OMs account for most of the cloud-nucleating ability of the entire aerosol population in the polluted air of northern China. We advocate that both size and composition - the two influential, controlling factors for aerosol activation - should be built into all regional climate models of China.

Microstructure and mechanical properties of electron beam welded dissimilar steel to Fe–Al alloy joints

Energy Technology Data Exchange (ETDEWEB)

Dinda, Soumitra Kumar; Basiruddin Sk, Md.; Roy, Gour Gopal [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Srirangam, Prakash, E-mail: p.srirangam@warwick.ac.uk [Warwick Manufacturing Group (WMG), University of Warwick, Coventry CV4 7AL (United Kingdom)

2016-11-20

Electron beam welding (EBW) technique was used to perform dissimilar joining of plain carbon steel to Fe–7%Al alloy under three different weld conditions such as with beam oscillation, without beam oscillation and at higher welding speed. The effect of weld parameters on the microstructure and mechanical properties of dissimilar joints was studied using optical microscopy, SEM, EBSD, hardness, tensile and erichsen cup tests. Microstructure results show that the application of beam oscillation resulted in uniform and homogeneous microstructure compared to without beam oscillations and higher welding speed. Further, it was observed that weld microstructure changes from equiaxed to columnar grains depending on the weld speed. High weld speed results in columnar grain structure in the weld joint. Erichsen cup test results show that the application of beam oscillation results in excellent formability as compared to high weld speed. Tensile test results show no significant difference in strength properties in all three weld conditions, but the ductility was found to be highest for joints obtained with the application of weld beam oscillation as compared to without beam oscillation and high weld speed. This study shows that the application of beam oscillations plays an important role in improving the weld quality and performance of EBW dissimilar steel to Fe–Al joints.

A comparison between different oxide dispersion strengthened ferritic steel ongoing in situ oxide dissolution in High Voltage Electron Microscope

International Nuclear Information System (INIS)

Monnet, I.; Van den Berghe, T.; Dubuisson, Ph.

2012-01-01

ODS materials are considered for nuclear applications but previous experimental studies have shown a partial dissolution of some oxides under neutron irradiation. In this work, electron irradiations were used to evaluate the stability of the oxides depending on the chemical composition of the oxide dispersion. Four ferritic steels based on EM10 (Fe–9Cr–1Mo) and reinforced respectively by Al 2 O 3 , MgO, MgAl 2 O 4 and Y 2 O 3 , were studied. These materials were irradiated with 1 MeV or 1.2 MeV electrons in a High Voltage Electron Microscope. This technique allows to follow one single oxide and to determine the evolution of its size during the irradiation. In situ HVEM observations indicate that the dissolution rate depends on the chemical composition of the oxide, on the temperature and on the irradiation dose.

Void nucleation in spheroidized steels during tensile deformation

International Nuclear Information System (INIS)

Fisher, J.R. Jr.

1980-04-01

An investigation was conducted to determine the effects of various mechanical and material parameters on void formation at cementite particles in axisymmetric tensile specimens of spheroidized plain carbon steels. Desired microstructures for each of three steel types were obtained. Observations of void morphology with respect to various microstructural features were made using optical and scanning electron microscopy

X-ray analysis in the steel industry

International Nuclear Information System (INIS)

Bourke, T.; Turner, K.

1999-01-01

Full text: The steel industry makes extensive use of X-ray analysis at all stages of the steelmaking process. XRF and XRD techniques, together with the associated techniques of electron probe microanalysis and electron microscopy are key tools for exploration and mine site and process development where detailed grade and mineralogical data is required. In production X-ray analysis is used to monitor and control: mine product grade (eg iron ore, coal and other raw materials), steel making production processes (eg iron ore sinter, incoming raw materials), waste products (eg coal watery refuse, slags) and final products (eg paint coatings, customer complaints). The demands put on X-ray analysis by the Steel Industry are severe. Iron ore mining and steelmaking is a continuous process, hence instrumentation has to be robust and reliable. In addition, with ever tightening environmental controls there is an increasing demand for trace heavy element analysis in both raw and waste materials. Copyright (1999) Australian X-ray Analytical Association Inc

Segregation effects in welded stainless steels

International Nuclear Information System (INIS)

Akhter, J.I.; Shoaid, K.A.; Ahmed, M.; Malik, A.Q.

1987-01-01

Welding of steels causes changes in the microstructure and chemical composition which could adversely affect the mechanical and corrosion properties. The report describes the experimental results of an investigation of segregation effects in welded austenitic stainless steels of AISI type 304, 304L, 316 and 316L using the techniques of scanning electron microscopy and electron probe microanalysis. Considerable enhancement of chromium and carbon has been observed in certain well-defined zones on the parent metal and on composition, particularly in the parent metal, in attributed to the formation of (M 23 C 6 ) precipitates. The formation of geometrically well-defined segregation zones is explained on the basis of the time-temperature-precipitation curve of (M 23 C 6 ). (author)

Optimally analyzing and implementing of bolt fittings in steel structure based on ANSYS

Science.gov (United States)

Han, Na; Song, Shuangyang; Cui, Yan; Wu, Yongchun

2018-03-01

ANSYS simulation software for its excellent performance become outstanding one in Computer-aided Engineering (CAE) family, it is committed to the innovation of engineering simulation to help users to shorten the design process. First, a typical procedure to implement CAE was design. The framework of structural numerical analysis on ANSYS Technology was proposed. Then, A optimally analyzing and implementing of bolt fittings in beam-column join of steel structure was implemented by ANSYS, which was display the cloud chart of XY-shear stress, the cloud chart of YZ-shear stress and the cloud chart of Y component of stress. Finally, ANSYS software simulating results was compared with the measured results by the experiment. The result of ANSYS simulating and analyzing is reliable, efficient and optical. In above process, a structural performance's numerical simulating and analyzing model were explored for engineering enterprises' practice.

+Cloud: An Agent-Based Cloud Computing Platform

OpenAIRE

González, Roberto; Hernández de la Iglesia, Daniel; de la Prieta Pintado, Fernando; Gil González, Ana Belén

2017-01-01

Cloud computing is revolutionizing the services provided through the Internet, and is continually adapting itself in order to maintain the quality of its services. This study presents the platform +Cloud, which proposes a cloud environment for storing information and files by following the cloud paradigm. This study also presents Warehouse 3.0, a cloud-based application that has been developed to validate the services provided by +Cloud.

Manufacture of Damascus steel: Metallographic study

International Nuclear Information System (INIS)

Criado, A.J.; Martinez, J.A.; Calabres, R.; Arias, D.

1997-01-01

Damascus Steel is the denomination that the Europeans gave to the material with which the musulman swords were manufactured during the Era of the Crusades. This hypereutectoid steel presents a high content in carbon more than 0.8%, and in some cases up to 2% in weight. The secret of its good mechanical characteristics is based in the hot forging process in the temperatures interval between 650 and 850 degree centigree. The final quenching in water brine or other aqueous solutions, confers to the swords manufactured with this steel a good resistance to its cutting edge and a high toughness. In the present investigation, the manufacture processes of this type of steel are studied. Electronic scanning microscopy has been applied to the study of materials manufactured by the authors following the ancient craftsmen methods of forging and quenching. (Author) 16 refs

Nanostructuring steel for injection molding tools

DEFF Research Database (Denmark)

Al-Azawi, A.; Smistrup, Kristian; Kristensen, Anders

2014-01-01

The production of nanostructured plastic items by injection molding with ridges down to 400 nm in width, which is the smallest line width replicated from nanostructured steel shims, is presented. Here we detail a micro-fabrication method where electron beam lithography, nano-imprint lithography...... and ion beam etching are combined to nanostructure the planar surface of a steel wafer. Injection molded plastic parts with enhanced surface properties, like anti-reflective, superhydrophobic and structural colors can be achieved by micro-and nanostructuring the surface of the steel molds. We investigate...... the minimum line width that can be realized by our fabrication method and the influence of etching angle on the structure profile during the ion beam etching process. Trenches down to 400 nm in width have been successfully fabricated into a 316 type electro-polished steel wafer. Afterward a plastic replica...

Thermal stability study for candidate stainless steels of GEN IV reactors

International Nuclear Information System (INIS)

Simeg Veternikova, J.; Degmova, J.; Pekarcikova, M.; Simko, F.; Petriska, M.; Skarba, M.; Mikula, P.; Pupala, M.

2016-01-01

Highlights: • Thermal resistance of advanced stainless steels were observed at 1000 °C. • GEN IV candidate steels were confronted to classic AISI steels. • ODS AISI 316 has weaker thermal resistance than classic AISI steel. • Ferritic ODS steels and NF 709 has better thermal resistance than AISI steels. - Abstract: Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

Thermal stability study for candidate stainless steels of GEN IV reactors

Energy Technology Data Exchange (ETDEWEB)

Simeg Veternikova, J., E-mail: jana.veternikova@stuba.sk [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Degmova, J. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pekarcikova, M. [Institute of Materials Science, Faculty of Materials Science and Technology, Slovak University of Technology, Paulinska 16, 917 24 Trnava (Slovakia); Simko, F. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia); Petriska, M. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Skarba, M. [Slovak University of Technology, Vazovova 5, 812 43 Bratislava (Slovakia); Mikula, P. [Institute of Nuclear and Physical Engineering, Faculty of Electrical and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Pupala, M. [Department of Molten Salts, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, 845 36 Bratislava (Slovakia)

2016-11-30

Highlights: • Thermal resistance of advanced stainless steels were observed at 1000 °C. • GEN IV candidate steels were confronted to classic AISI steels. • ODS AISI 316 has weaker thermal resistance than classic AISI steel. • Ferritic ODS steels and NF 709 has better thermal resistance than AISI steels. - Abstract: Candidate stainless steels for GEN IV reactors were investigated in term of thermal and corrosion stability at high temperatures. New austenitic steel (NF 709), austenitic ODS steel (ODS 316) and two ferritic ODS steels (MA 956 and MA 957) were exposed to around 1000 °C in inert argon atmosphere at pressure of ∼8 MPa. The steels were further studied in a light of vacancy defects presence by positron annihilation spectroscopy and their thermal resistance was confronted to classic AISI steels. The thermal strain supported a creation of oxide layers observed by scanning electron microscopy (SEM).

Experimental investigations on fiber laser color marking of steels

Energy Technology Data Exchange (ETDEWEB)

Amara, E.H., E-mail: amara@cdta.dz; Haïd, F.; Noukaz, A.

2015-10-01

Highlights: • We develop an experimental approach with the aim to bring a contribution to the comprehension of the occurring phenomena during laser color marking of steels. • We have used a home-made marking device composed of a pulsed fiber laser and galvanometric mirrors. • Both commercial and elaborated in laboratory steels have been used as samples. • The experiments have been performed for different laser beam operating parameters, under normal atmospheric conditions. • The treated samples were analyzed either by optical and scanning electronic microscopy, as well as by energy dispersion spectroscopy. - Abstract: We develop an experimental approach with the aim to bring a contribution to the comprehension of the occurring phenomena during laser color marking of steels. A home-made marking device using a pulsed fiber laser has been used to treat steel samples under different laser beam operating parameters, for different compositions of the processed steel, and at normal atmospheric conditions. The treated samples were analyzed either by optical and scanning electronic microscopy, as well as by energy dispersion spectroscopy. The results show the influence of the operating parameters on the obtained colors.

Experimental investigations on fiber laser color marking of steels

International Nuclear Information System (INIS)

Amara, E.H.; Haïd, F.; Noukaz, A.

2015-01-01

Highlights: • We develop an experimental approach with the aim to bring a contribution to the comprehension of the occurring phenomena during laser color marking of steels. • We have used a home-made marking device composed of a pulsed fiber laser and galvanometric mirrors. • Both commercial and elaborated in laboratory steels have been used as samples. • The experiments have been performed for different laser beam operating parameters, under normal atmospheric conditions. • The treated samples were analyzed either by optical and scanning electronic microscopy, as well as by energy dispersion spectroscopy. - Abstract: We develop an experimental approach with the aim to bring a contribution to the comprehension of the occurring phenomena during laser color marking of steels. A home-made marking device using a pulsed fiber laser has been used to treat steel samples under different laser beam operating parameters, for different compositions of the processed steel, and at normal atmospheric conditions. The treated samples were analyzed either by optical and scanning electronic microscopy, as well as by energy dispersion spectroscopy. The results show the influence of the operating parameters on the obtained colors

Precipitation behavior of carbides in high-carbon martensitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Zhu, Qin-tian; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao; Shi, Chang-min [University of Science and Technology, Beijing (China). State Key Laboratory of Advanced Metallurgy; Li, Ji-hui [Yang Jiang Shi Ba Zi Group Co., Ltd, Guangdong (China)

2017-01-15

A fundamental study on the precipitation behavior of carbides was carried out. Thermo-calc software, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, X-ray diffractometry and high-temperature confocal laser scanning microscopy were used to study the precipitation and transformation behaviors of carbides. Carbide precipitation was of a specific order. Primary carbides (M7C3) tended to be generated from liquid steel when the solid fraction reached 84 mol.%. Secondary carbides (M7C3) precipitated from austenite and can hardly transformed into M23C6 carbides with decreasing temperature in air. Primary carbides hardly changed once they were generated, whereas secondary carbides were sensitive to heat treatment and thermal deformation. Carbide precipitation had a certain effect on steel-matrix phase transitions. The segregation ability of carbon in liquid steel was 4.6 times greater that of chromium. A new method for controlling primary carbides is proposed.

Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

Energy Technology Data Exchange (ETDEWEB)

Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil [School of Applied Physic, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2014-09-03

Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

Electron backscatter diffraction study of deformation and recrystallization textures of individual phases in a cross-rolled duplex steel

Energy Technology Data Exchange (ETDEWEB)

Zaid, Md; Bhattacharjee, P.P., E-mail: pinakib@iith.ac.in

2014-10-15

The evolution of microstructure and texture during cross-rolling and annealing was investigated by electron backscatter diffraction in a ferritic–austenitic duplex stainless steel. For this purpose an alloy with nearly equal volume fraction of the two phases was deformed by multi-pass cross-rolling process up to 90% reduction in thickness. The rolling and transverse directions were mutually interchanged in each pass by rotating the sample by 90° around the normal direction. In order to avoid deformation induced phase transformation and dynamic strain aging, the rolling was carried out at an optimized temperature of 898 K (625 °C) at the warm-deformation range. The microstructure after cross warm-rolling revealed a lamellar structure with alternate arrangement of the bands of two phases. Strong brass and rotated brass components were observed in austenite in the steel after processing by cross warm-rolling. The ferrite in the cross warm-rolling processed steel showed remarkably strong RD-fiber (RD//< 011 >) component (001)< 011 >. The development of texture in the two phases after processing by cross warm-rolling could be explained by the stability of the texture components. During isothermal annealing of the 90% cross warm-rolling processed material the lamellar morphology was retained before collapse of the lamellar structure to the mutual interpenetration of the phase bands. Ferrite showed recovery resulting in annealing texture similar to the deformation texture. In contrast, the austenite showed primary recrystallization without preferential orientation selection leading to the retention of deformation texture. The evolution of deformation and annealing texture in the two phases of the steel was independent of one another. - Highlights: • Effect of cross warm-rolling on texture formation is studied in duplex steel. • Brass texture in austenite and (001)<110 > in ferrite are developed. • Ferrite shows recovery during annealing retaining the (001

Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

International Nuclear Information System (INIS)

Dumas, Claire; Basseguy, Regine; Bergel, Alain

2008-01-01

Stainless steel and graphite electrodes were individually addressed and polarized at -0.60 V vs. Ag/AgCl in reactors filled with a growth medium that contained 25 mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75 A m -2 for graphite and 20.5 A m -2 for stainless steel. Cyclic voltammetry performed at the end of the experiment indicated that the reduction started at around -0.30 V vs. Ag/AgCl on stainless steel. Removing the biofilm formed on the electrode surface made the current totally disappear, confirming that the G.sulfurreducens biofilm was fully responsible for the electrocatalysis of fumarate reduction. Similar current densities were recorded when the electrodes were polarized after being kept in open circuit for several days. The reasons for the bacteria presence and survival on non-connected stainless steel coupons were discussed. Chronoamperometry experiments performed at different potential values suggested that the biofilm-driven catalysis was controlled by electrochemical kinetics. The high current density obtained, quite close to the redox potential of the fumarate/succinate couple, presents stainless steel as a remarkable material to support biocathodes

The interaction of fast alpha particles with pellet ablation clouds

International Nuclear Information System (INIS)

McChesney, J.M.; Parks, P.B.; Fisher, R.K.; Olson, R.E.

1997-01-01

The energy spectra of energetic confined alpha particles are being measured using the pellet charge exchange method [R. K. Fisher, J. S. Leffler, A. M. Howald, and P. B. Parks, Fusion Technol. 13, 536 (1988)]. The technique uses the dense ablation cloud surrounding an injected impurity pellet to neutralize a fraction of the incident alpha particles, allowing them to escape from the plasma where their energy spectrum can be measured using a neutral particle analyzer. The signal calculations given in the above-mentioned reference disregarded the effects of the alpha particles' helical Larmor orbits, which causes the alphas to make multiple passes through the cloud. Other effects such as electron ionization by plasma and ablation cloud electrons and the effect of the charge state composition of the cloud, were also neglected. This report considers these issues, reformulates the signal level calculation, and uses a Monte-Carlo approach to calculate the neutralization fractions. The possible effects of energy loss and pitch angle scattering of the alphas are also considered. copyright 1997 American Institute of Physics

Surface Nano crystallization of 3Cr13 Stainless Steel Induced by High-Current Pulsed Electron Beam Irradiation

International Nuclear Information System (INIS)

Han, Z.; Zou, H.; Wang, Z.; Ji, I.; Cai, J.; Guan, Q.

2013-01-01

The nanocrystalline surface was produced on 3Cr13 martensite stainless steel surface using high-current pulsed electron beam (HCPEB) technique. The structures of the nano crystallized surface were characterized by X-ray diffraction and electron microscopy. Two nano structures consisting of fine austenite grains (50-150 nm) and very fine carbides precipitates are formed in melted surface layer after multiple bombardments via dissolution of carbides and crater eruption. It is demonstrated that the dissolution of the carbides and the formation of the supersaturated Fe (C) solid solution play a determining role on the microstructure evolution. Additionally, the formation of fine austenite structure is closely related to the thermal stresses induced by the HCPEB irradiation. The effects of both high carbon content and high value of stresses increase the stability of the austenite, which leads to the complete suppression of martensitic transformation.

Splitting in Dual-Phase 590 high strength steel plates

International Nuclear Information System (INIS)

Yang Min; Chao, Yuh J.; Li Xiaodong; Tan Jinzhu

2008-01-01

Charpy V-notch impact tests on 5.5 mm thick, hot-rolled Dual-Phase 590 (DP590) steel plate were evaluated at temperatures ranging from 90 deg. C to -120 deg. C. Similar tests on 2.0 mm thick DP590 HDGI steel plate were also conducted at room temperature. Splitting or secondary cracks was observed on the fractured surfaces. The mechanisms of the splitting were then investigated. Fracture surfaces were analyzed by optical microscope (OM) and scanning electron microscope (SEM). Composition of the steel plates was determined by electron probe microanalysis (EPMA). Micro Vickers hardness of the steel plates was also surveyed. Results show that splitting occurred on the main fractured surfaces of hot-rolled steel specimens at various testing temperatures. At temperatures above the ductile-brittle-transition-temperature (DBTT), -95 deg. C, where the fracture is predominantly ductile, the length and amount of splitting decreased with increasing temperature. At temperatures lower than the DBTT, where the fracture is predominantly brittle, both the length and width of the splitting are insignificant. Splitting in HDGI steel plates only appeared in specimens of T-L direction. The analysis revealed that splitting in hot-rolled plate is caused by silicate and carbide inclusions while splitting in HDGI plate results from strip microstructure due to its high content of manganese and low content of silicon. The micro Vickers hardness of either the inclusions or the strip microstructures is higher than that of the respective base steel

Damage Assessment of Heat Resistant Steels through Electron BackScatter Diffraction Strain Analysis under Creep and Creep-Fatigue Conditions

Science.gov (United States)

Fujiyama, Kazunari; Kimachi, Hirohisa; Tsuboi, Toshiki; Hagiwara, Hiroyuki; Ogino, Shotaro; Mizutani, Yoshiki

EBSD(Electron BackScatter Diffraction) analyses were conducted for studying the quantitative microstructural metrics of creep and creep-fatigue damage for austenitic SUS304HTB boiler tube steel and ferritic Mod.9Cr piping steel. KAM(Kernel Average Misorientation) maps and GOS(Grain Orientation Spread) maps were obtained for these samples and the area averaged values KAMave and GOSave were obtained. While the increasing trends of these misorientation metrics were observed for SUS304HTB steel, the decreasing trends were observed for damaged Mod.9Cr steel with extensive recovery of subgrain structure. To establish more universal parameter representing the accumulation of damage to compensate these opposite trends, the EBSD strain parameters were introduced for converting the misorientation changes into the quantities representing accumulated permanent strains during creep and creep-fatigue damage process. As KAM values were dependent on the pixel size (inversely proportional to the observation magnification) and the permanent strain could be expressed as the shear strain which was the product of dislocation density, Burgers vector and dislocation movement distance, two KAM strain parameters MεKAMnet and MεδKAMave were introduced as the sum of product of the noise subtracted KAMnet and the absolute change from initial value δKAMave with dislocation movement distance divided by pixel size. MεδKAMave parameter showed better relationship both with creep strain in creep tests and accumulated creep strain range in creep-fatigue tests. This parameter can be used as the strain-based damage evaluation and detector of final failure.

Effect of laser and/or electron beam irradiation on void swelling in SUS316L austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Yang, Subing [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Zhanbing, E-mail: yangzhanbing@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Hui [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Watanabe, Seiichi; Shibayama, Tamaki [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan)

2017-05-15

Large amounts of void swelling still limit the application of austenitic stainless steels in nuclear reactors due to radiation-induced lattice point defects. In this study, laser and/or beam irradiation was conducted in a temperature range of 573–773 K to explore the suppression of void swelling. The results show that during sequential laser-electron beam irradiation, the void nucleation is enhanced because of the vacancy clusters and void nuclei formed under pre-laser irradiation, causing greater void swelling than single electron beam irradiation. However, simultaneous laser-electron dual-beam irradiation exhibits an obvious suppression effect on void swelling due to the enhanced recombination between interstitials and vacancies in the temperature range of 573–773 K; especially at 723 K, the swelling under simultaneous dual-beam irradiation is 0.031% which is only 22% of the swelling under electron beam irradiation (0.137%). These results provide new insight into the suppression of void swelling during irradiation. - Highlights: •The temperature dependence of void swelling under simultaneous laser-electron dual-beam irradiation has been investigated. •Pre-laser irradiation enhances void nucleation at temperatures from 573 K to 773 K. •Simultaneous laser-electron dual-beam irradiation suppresses void swelling in the temperature range of 573–773 K.

Silicon Photonics Cloud (SiCloud)

DEFF Research Database (Denmark)

DeVore, P. T. S.; Jiang, Y.; Lynch, M.

2015-01-01

Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

Anodized Steel Electrodes for Supercapacitors.

Science.gov (United States)

Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

2016-03-09

Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.

Kinetics of laser irradiated nanoparticles cloud

Science.gov (United States)

Mishra, S. K.; Upadhyay Kahaly, M.; Misra, Shikha

2018-02-01

A comprehensive kinetic model describing the complex kinetics of a laser irradiated nanoparticle ensemble has been developed. The absorbed laser radiation here serves dual purpose, viz., photoenhanced thermionic emission via rise in its temperature and direct photoemission of electrons. On the basis of mean charge theory along with the equations for particle (electron) and energy flux balance over the nanoparticles, the transient processes of charge/temperature evolution over its surface and mass diminution on account of the sublimation (phase change) process have been elucidated. Using this formulation phenomenon of nanoparticle charging, its temperature rise to the sublimation point, mass ablation, and cloud disintegration have been investigated; afterwards, typical timescales of disintegration, sublimation and complete evaporation in reference to a graphite nanoparticle cloud (as an illustrative case) have been parametrically investigated. Based on a numerical analysis, an adequate parameter space describing the nanoparticle operation below the sublimation temperature, in terms of laser intensity, wavelength and nanoparticle material work function, has been identified. The cloud disintegration is found to be sensitive to the nanoparticle charging through photoemission; as a consequence, it illustrates that radiation operating below the photoemission threshold causes disintegration in the phase change state, while above the threshold, it occurs with the onset of surface heating.

Cloud computing in pharmaceutical R&D: business risks and mitigations.

Science.gov (United States)

Geiger, Karl

2010-05-01

Cloud computing provides information processing power and business services, delivering these services over the Internet from centrally hosted locations. Major technology corporations aim to supply these services to every sector of the economy. Deploying business processes 'in the cloud' requires special attention to the regulatory and business risks assumed when running on both hardware and software that are outside the direct control of a company. The identification of risks at the correct service level allows a good mitigation strategy to be selected. The pharmaceutical industry can take advantage of existing risk management strategies that have already been tested in the finance and electronic commerce sectors. In this review, the business risks associated with the use of cloud computing are discussed, and mitigations achieved through knowledge from securing services for electronic commerce and from good IT practice are highlighted.

An Efficient Searchable Encryption Against Keyword Guessing Attacks for Sharable Electronic Medical Records in Cloud-based System.

Science.gov (United States)

Wu, Yilun; Lu, Xicheng; Su, Jinshu; Chen, Peixin

2016-12-01

Preserving the privacy of electronic medical records (EMRs) is extremely important especially when medical systems adopt cloud services to store patients' electronic medical records. Considering both the privacy and the utilization of EMRs, some medical systems apply searchable encryption to encrypt EMRs and enable authorized users to search over these encrypted records. Since individuals would like to share their EMRs with multiple persons, how to design an efficient searchable encryption for sharable EMRs is still a very challenge work. In this paper, we propose a cost-efficient secure channel free searchable encryption (SCF-PEKS) scheme for sharable EMRs. Comparing with existing SCF-PEKS solutions, our scheme reduces the storage overhead and achieves better computation performance. Moreover, our scheme can guard against keyword guessing attack, which is neglected by most of the existing schemes. Finally, we implement both our scheme and a latest medical-based scheme to evaluate the performance. The evaluation results show that our scheme performs much better performance than the latest one for sharable EMRs.

Cloud Processed CCN Suppress Stratus Cloud Drizzle

Science.gov (United States)

Hudson, J. G.; Noble, S. R., Jr.

2017-12-01

Conversion of sulfur dioxide to sulfate within cloud droplets increases the sizes and decreases the critical supersaturation, Sc, of cloud residual particles that had nucleated the droplets. Since other particles remain at the same sizes and Sc a size and Sc gap is often observed. Hudson et al. (2015) showed higher cloud droplet concentrations (Nc) in stratus clouds associated with bimodal high-resolution CCN spectra from the DRI CCN spectrometer compared to clouds associated with unimodal CCN spectra (not cloud processed). Here we show that CCN spectral shape (bimodal or unimodal) affects all aspects of stratus cloud microphysics and drizzle. Panel A shows mean differential cloud droplet spectra that have been divided according to traditional slopes, k, of the 131 measured CCN spectra in the Marine Stratus/Stratocumulus Experiment (MASE) off the Central California coast. K is generally high within the supersaturation, S, range of stratus clouds (< 0.5%). Because cloud processing decreases Sc of some particles, it reduces k. Panel A shows higher concentrations of small cloud droplets apparently grown on lower k CCN than clouds grown on higher k CCN. At small droplet sizes the concentrations follow the k order of the legend, black, red, green, blue (lowest to highest k). Above 13 µm diameter the lines cross and the hierarchy reverses so that blue (highest k) has the highest concentrations followed by green, red and black (lowest k). This reversed hierarchy continues into the drizzle size range (panel B) where the most drizzle drops, Nd, are in clouds grown on the least cloud-processed CCN (blue), while clouds grown on the most processed CCN (black) have the lowest Nd. Suppression of stratus cloud drizzle by cloud processing is an additional 2nd indirect aerosol effect (IAE) that along with the enhancement of 1st IAE by higher Nc (panel A) are above and beyond original IAE. However, further similar analysis is needed in other cloud regimes to determine if MASE was

Effect of substrates on microstructure and mechanical properties of nano-eutectic 1080 steel produced by aluminothermic reaction

International Nuclear Information System (INIS)

La, Peiqing; Li, Zhengning; Li, Cuiling; Hu, Sulei; Lu, Xuefeng; Wei, Yupeng; Wei, Fuan

2014-01-01

Nano-eutectic bulk 1080 carbon steel was prepared on glass and copper substrates by an aluminothermic reaction casting. The microstructure of the steel was analyzed by an optical microscope, transmission electron microscopy, an electron probe micro-analyzer, a scanning electron microscope and X-ray diffraction. Results show that the microstructure of the steel consisted of a little cementite and lamellar eutectic pearlite. Average lamellar spacing of the pearlite prepared on copper and glass substrates was about 230 nm and 219 nm, respectively. Volume fraction of the pearlite of the two steels was about 95%. Hardness of the steel was about 229 and 270 HV. Tensile strength was about 610 and 641 MPa and tensile elongation was about 15% and 8%. Compressive strength was about 1043 and 1144 MPa. Compared with the steel prepared on copper substrate, the steel prepared on glass substrate had smaller lamellar spacing of the pearlite phase and higher strength, and low ductility due to the smaller spacing. - Highlights: • 1080-carbon steels were successfully prepared by an aluminothermic reaction casting. • Lamellar spacing of the nanoeutetic pearlite is less than 250 nm. • The compressive strength of the steel is about 1144 MPa. • The tensile ductility of the steel is about 15%

Simple structure diffusion cloud chamber for educational purpose

International Nuclear Information System (INIS)

Hrehuss, Gy.; Molnar, B.

1982-01-01

A simple structure diffusion cloud chamber was designed and built with educational aim. The source of alpha particles is Am-241 radioisotope smeared on steel foil, the source of vapor is a felt disc saturated with methanol. Five minutes after covering the chamber the system achieves the thermodynamic equilibrium and alpha particle tracks of 5 cm length become visible in the centre of the chamber. Life-time of a track is about 0.5-1 second, the frequency is 2-3 tracks/s. The presented diffusion chamber can be built simply and easily, using cheap common materials and components. (D.Gy.)

Considerations about Cloud Services: Learning

Directory of Open Access Journals (Sweden)

Riccardo Cognini

2013-05-01

Full Text Available Cloud services are ubiquitous: for small to large companies the phenomenon of cloud service is nowadays a standard business practice. This paper would compile an analysis over a possible implementation of a cloud system, treating especially the legal aspect of this theme. In the Italian market has a large number of issues arise form cloud computing. First of all, this paper investigates the legal issues associated to cloud computing, specific contractual scheme that is able to define rights a duties both of user (private and/or public body and cloud provider. On one side there is all the EU legislative production related to privacy over electronic communication and, furthermore, the Privacy Directive is under a revision process to be more adaptable to new challenges of decentralized data treatment, but concretely there are no any structured and well defined legal instruments. Objectives: we present a possible solution to address the uncertainty of this area, starting from the EU legislative production with the help of the specific Italian scenario that could offer an operative solution. Indeed the Italian legal system is particularly adaptable to changing technologies and it could use as better as possible to adapt the already existing legal tools to this new technological era. Prior work: after an introduction to the state of the art, we show the main issues and their critical points that must be solved. Approach: observation of the state of the art to propose a new approach to find the suitable disciple

EBSD spatial resolution for detecting sigma phase in steels

Energy Technology Data Exchange (ETDEWEB)

Bordín, S. Fernandez; Limandri, S. [Instituto de Física Enrique Gaviola, CONICET. M. Allende s/n, Ciudad Universitaria, 5000 Córdoba (Argentina); Ranalli, J.M. [Comisión Nacional de Energía Atómica, Av. Gral. Paz 1499, San Martín, 1650 Buenos Aires (Argentina); Castellano, G. [Instituto de Física Enrique Gaviola, CONICET. M. Allende s/n, Ciudad Universitaria, 5000 Córdoba (Argentina)

2016-12-15

The spatial resolution of the electron backscatter diffraction signal is explored by Monte Carlo simulation for the sigma phase in steel at a typical instrumental set-up. In order to estimate the active volume corresponding to the diffracted electrons, the fraction of the backscattered electrons contributing to the diffraction signal was inferred by extrapolating the Kikuchi pattern contrast measured by other authors, as a function of the diffracted electron energy. In the resulting estimation, the contribution of the intrinsic incident beam size and the software capability to deconvolve patterns were included. A strong influence of the beam size on the lateral resolution was observed, resulting in 20 nm for the aperture considered. For longitudinal and depth directions the resolutions obtained were 75 nm and 16 nm, respectively. The reliability of this last result is discussed in terms of the survey of the last large-angle deflection undergone by the backscattered electrons involved in the diffraction process. Bearing in mind the mean transversal resolution found, it was possible to detect small area grains of sigma phase by EBSD measurements, for a stabilized austenitic AISI 347 stainless steel under heat treatments, simulating post welding (40 h at 600 °C) and aging (284 h at 484 °C) effects—as usually occurring in nuclear reactor pressure vessels. - Highlights: • EBSD spatial resolution is studied by Monte Carlo simulation for σ-phase in steel. • The contribution of the intrinsic incident beam size was included. • A stabilized austenitic stainless steel under heat treatments was measured by EBSD. • With the transversal resolution found, small area σ-phase grains could be identified.

Characterisation of Pristine and Recoated electron beam evaporation plasma-assisted physical vapour deposition Cr-N coatings on AISI M2 steel and WC-Co substrates

International Nuclear Information System (INIS)

Avelar-Batista, J.C.; Spain, E.; Housden, J.; Fuentes, G.G.; Rebole, R.; Rodriguez, R.; Montala, F.; Carreras, L.J.; Tate, T.J.

2005-01-01

This paper is focussed on the characterisation of electron beam evaporation plasma-assisted physical vapour deposition Cr-N coatings deposited on AISI M2 steel and hardmetal (K10) substrates in two different conditions: Pristine (i.e., coated) and Recoated (i.e., stripped and recoated). Analytical methods, including X-ray diffraction (XRD), scanning electron microscopy, scratch adhesion and pin-on-disc tests were used to evaluate several coating properties. XRD analyses indicated that both Pristine and Recoated coatings consisted of a mixture of hexagonal Cr 2 N and cubic CrN, regardless of substrate type. For the M2 steel substrate, only small differences were found in terms of coating phases, microstructure, adhesion, friction and wear coefficients between Pristine and Recoated. Recoated on WC-Co (K10) exhibited a less dense microstructure and significant inferior adhesion compared to Pristine on WC-Co (K10). The wear coefficient of Recoated on WC-Co was 100 times higher than those exhibited by all other specimens. The results obtained confirm that the stripping process did not adversely affect the Cr-N properties when this coating was deposited onto M2 steel substrates, but it is clear from the unsatisfactory tribological performance of Recoated on WC-Co that the stripping process is unsuitable for hardmetal substrates

Mitigation of the electron-cloud effect in the PSR and SNS proton storage rings by tailoring the bunch profile

International Nuclear Information System (INIS)

Pivi, M.; Furman, M.A.

2003-01-01

For the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electroncloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

Cloud vertical profiles derived from CALIPSO and CloudSat and a comparison with MODIS derived clouds

Science.gov (United States)

Kato, S.; Sun-Mack, S.; Miller, W. F.; Rose, F. G.; Minnis, P.; Wielicki, B. A.; Winker, D. M.; Stephens, G. L.; Charlock, T. P.; Collins, W. D.; Loeb, N. G.; Stackhouse, P. W.; Xu, K.

2008-05-01

CALIPSO and CloudSat from the a-train provide detailed information of vertical distribution of clouds and aerosols. The vertical distribution of cloud occurrence is derived from one month of CALIPSO and CloudSat data as a part of the effort of merging CALIPSO, CloudSat and MODIS with CERES data. This newly derived cloud profile is compared with the distribution of cloud top height derived from MODIS on Aqua from cloud algorithms used in the CERES project. The cloud base from MODIS is also estimated using an empirical formula based on the cloud top height and optical thickness, which is used in CERES processes. While MODIS detects mid and low level clouds over the Arctic in April fairly well when they are the topmost cloud layer, it underestimates high- level clouds. In addition, because the CERES-MODIS cloud algorithm is not able to detect multi-layer clouds and the empirical formula significantly underestimates the depth of high clouds, the occurrence of mid and low-level clouds is underestimated. This comparison does not consider sensitivity difference to thin clouds but we will impose an optical thickness threshold to CALIPSO derived clouds for a further comparison. The effect of such differences in the cloud profile to flux computations will also be discussed. In addition, the effect of cloud cover to the top-of-atmosphere flux over the Arctic using CERES SSF and FLASHFLUX products will be discussed.

From EDI to Internet Commerce: The BHP Steel Experience.

Science.gov (United States)

Chan, Caroline; Swatman, Paula M. C.

2000-01-01

Discusses the issue of business-to-business electronic commerce implementation and the factors affecting it. Discusses electronic data interchange technology, describes the results of a case study of BHP Steel (Australia), and considers paradigm shifts in implementation issues related to electronic commerce that occur over time. (Author/LRW)

CLOUD EDUCATIONAL RESOURCES FOR PHYSICS LEARNING RESEARCHES SUPPORT

Directory of Open Access Journals (Sweden)

Oleksandr V. Merzlykin

2015-10-01

Full Text Available The definition of cloud educational resource is given in paper. Its program and information components are characterized. The virtualization as the technological ground of transforming from traditional electronic educational resources to cloud ones is reviewed. Such levels of virtualization are described: data storage device virtualization (Data as Service, hardware virtualization (Hardware as Service, computer virtualization (Infrastructure as Service, software system virtualization (Platform as Service, «desktop» virtualization (Desktop as Service, software user interface virtualization (Software as Service. Possibilities of designing the cloud educational resources system for physics learning researches support taking into account standards of learning objects metadata (accessing via OAI-PMH protocol and standards of learning tools interoperability (LTI are shown. The example of integration cloud educational resources into Moodle learning management system with use of OAI-PMH and LTI is given.

Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

CERN Document Server

Kuzucan, Asena; Taborelli, Mauro

2011-01-01

In LHC the electron cloud induced by photoelectrons, gas ionization and secondary electrons emitted from the beam pipe walls could be a limitation of the performance. The electron cloud induce heat load on the cryogenic system, cause pressure rise, emittance growth and beam instabilities, which in the end will limit the beam’s lifetime. Beam- induced multipacting, which can arise through oscillatory motion of photoelectrons and low-energy secondary electrons bouncing back and forth between opposite walls of the vacuum chamber during successive passage of proton bunches, represent therefore a potential problem for the machine. The secondary electron yield (SEY) is one of the key parameters for the electron cloud build up and multipacting phenomenon. An electron cloud occurs if the metal surface secondary electron yield is high enough for electron multiplication. This parameter has been extensively studied on room temperature samples but uncertainties remain for samples at cryogenic temperature. Indeed, at l...

Damage and fatigue crack growth of Eurofer steel first wall mock-up under cyclic heat flux loads. Part 1: Electron beam irradiation tests

Energy Technology Data Exchange (ETDEWEB)

You, J.H., E-mail: you@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Euratom Association, Boltzmannstr. 2, 85748 Garching (Germany); Höschen, T. [Max-Planck-Institut für Plasmaphysik, Euratom Association, Boltzmannstr. 2, 85748 Garching (Germany); Pintsuk, G. [Forschungszentrum Jülich GmbH, IEK2, Euratom Association, 52425 Jülich (Germany)

2014-04-15

Highlights: • Clear evidence of microscopic damage and crack formation at the notch root in the early stage of the fatigue loading (50–100 load cycles). • Propagation of fatigue crack at the notch root in the course of subsequent cyclic heat-flux loading followed by saturation after roughly 600 load cycles. • No sign of damage on the notch-free surface up to 800 load cycles. • No obvious effect of the pulse time duration on the crack extension. • Slight change in the grain microstructure due to the formation of sub-grain boundaries by plastic deformation. - Abstract: Recently, the idea of bare steel first wall (FW) is drawing attention, where the surface of the steel is to be directly exposed to high heat flux loads. Hence, the thermo-mechanical impacts on the bare steel FW will be different from those of the tungsten-coated one. There are several previous works on the thermal fatigue tests of bare steel FW made of austenitic steel with regard to the ITER application. In the case of reduced-activation steel Eurofer97, a candidate structural material for the DEMO FW, there is no report on high heat flux tests yet. The aim of the present study is to investigate the thermal fatigue behavior of the Eurofer-based bare steel FW under cyclic heat flux loads relevant to DEMO operation. To this end, we conducted a series of electron beam irradiation tests with heat flux load of 3.5 MW/m{sup 2} on water-cooled mock-ups with an engraved thin notch on the surface. It was found that the notch root region exhibited a marked development of damage and fatigue cracks whereas the notch-free surface manifested no sign of crack formation up to 800 load cycles. Results of extensive microscopic investigation are reported.

Study on tempering behaviour of AISI 410 stainless steel

International Nuclear Information System (INIS)

Chakraborty, Gopa; Das, C.R.; Albert, S.K.; Bhaduri, A.K.; Thomas Paul, V.; Panneerselvam, G.; Dasgupta, Arup

2015-01-01

Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-ray diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M 23 C 6 ) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe 2 C and M 23 C 6 types of carbides coexisting in the material. The nucleation of Fe 2 C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M 23 C 6 carbides, instead of Fe 2 C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of carbide precipitation varies with

Electron work function-a promising guiding parameter for material design.

Science.gov (United States)

Lu, Hao; Liu, Ziran; Yan, Xianguo; Li, Dongyang; Parent, Leo; Tian, Harry

2016-04-14

Using nickel added X70 steel as a sample material, we demonstrate that electron work function (EWF), which largely reflects the electron behavior of materials, could be used as a guide parameter for material modification or design. Adding Ni having a higher electron work function to X70 steel brings more "free" electrons to the steel, leading to increased overall work function, accompanied with enhanced e(-)-nuclei interactions or higher atomic bond strength. Young's modulus and hardness increase correspondingly. However, the free electron density and work function decrease as the Ni content is continuously increased, accompanied with the formation of a second phase, FeNi3, which is softer with a lower work function. The decrease in the overall work function corresponds to deterioration of the mechanical strength of the steel. It is expected that EWF, a simple but fundamental parameter, may lead to new methodologies or supplementary approaches for metallic materials design or tailoring on a feasible electronic base.

Effect of N+Cr alloying on the microstructures and tensile properties of Hadfield steel

International Nuclear Information System (INIS)

Chen, C.; Zhang, F.C.; Wang, F.; Liu, H.; Yu, B.D.

2017-01-01

The microstructures and tensile behaviors of traditional Hadfield steel, named Mn12 steel, and Hadfield steel alloyed with N+Cr, named Mn12CrN steel were studied through optical microscopy, transmission electron microscopy, and scanning electron microscopy, among others. Three different tensile strain rates of 5×10 −4 , 5×10 −3 , and 5×10 −2 s −1 were selected in the tensile test. The deformation microstructures and fracture morphologies of the two steels after fracture in the tensile test were observed to analyze the tensile deformation response to different tensile strain rates. Results showed that the grain size of Mn12CrN steel was evidently refined after alloying with N+Cr. The grain would not become abnormally coarse even with increasing austenitizing temperature. During tensile deformation, the strength and plasticity of Mn12CrN steel were superior to those of Mn12 steel at the same strain rate. With increasing the strain rate, the changes in strength and plasticity of Mn12CrN steel were less sensitive to tensile strain rate compared with Mn12 steel. The effects of grain refinement and N+Cr alloying on dynamic strain aging and deformation twining behaviors were responsible for this lack of sensitivity to strain rate.

Effect of Pulse Detonation-Plasma Technology Treatment on T8 Steel Microstructures

Science.gov (United States)

Yu, Jiuming; Zhang, Linwei; Liu, Keming; Lu, Lei; Lu, Deping; Zhou, Haitao

2017-12-01

T8 steel surfaces were treated by pulse detonation-plasma technology (PDT) at capacitance values of 600, 800, and 1000 μF, and the effects of PDT were analyzed using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron back-scattered diffraction, and micro-hardness tester and friction wear tester. The surface of T8 steel is first smoothed out, and then, craters are formed due to the inhomogeneity of the PDT energy and targeting during PDT treatment. The initial martensite in the T8 steel surface layer changes to austenite, and Fe3N is formed due to nitriding. The thickness of the modified layer, which is composed of columnar and fine grain structures, increases with the increasing capacity. Preferential orientation occurred in the {110} 〈 001 〉 direction in the modified layer, and the number of low-angle grain boundaries increased significantly after PDT treatment. The micro-hardness and wear resistance of the T8 steel was improved by PDT treatment, even doubled after the treatment with the capacitance of 1000 μF.

Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

Science.gov (United States)

Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

2017-10-01

Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

Recent characterization of steel by surface analysis methods

International Nuclear Information System (INIS)

Suzuki, Shigeru

1996-01-01

Surface analysis methods, such as Auger electron spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, glow discharge optical emission spectrometry and so on, have become indispensable to characterize surface and interface of many kinds of steel. Although a number of studies on characterization of steel by these methods have been carried out, several problems still remain in quantification and depth profiling. Nevertheless, the methods have provided essential information on the concentration and chemical state of elements at the surface and interface. Recent results on characterization of oxide layers, coated films, etc. on the surface of steel are reviewed here. (author). 99 refs

iMAGE cloud: medical image processing as a service for regional healthcare in a hybrid cloud environment.

Science.gov (United States)

Liu, Li; Chen, Weiping; Nie, Min; Zhang, Fengjuan; Wang, Yu; He, Ailing; Wang, Xiaonan; Yan, Gen

2016-11-01

To handle the emergence of the regional healthcare ecosystem, physicians and surgeons in various departments and healthcare institutions must process medical images securely, conveniently, and efficiently, and must integrate them with electronic medical records (EMRs). In this manuscript, we propose a software as a service (SaaS) cloud called the iMAGE cloud. A three-layer hybrid cloud was created to provide medical image processing services in the smart city of Wuxi, China, in April 2015. In the first step, medical images and EMR data were received and integrated via the hybrid regional healthcare network. Then, traditional and advanced image processing functions were proposed and computed in a unified manner in the high-performance cloud units. Finally, the image processing results were delivered to regional users using the virtual desktop infrastructure (VDI) technology. Security infrastructure was also taken into consideration. Integrated information query and many advanced medical image processing functions-such as coronary extraction, pulmonary reconstruction, vascular extraction, intelligent detection of pulmonary nodules, image fusion, and 3D printing-were available to local physicians and surgeons in various departments and healthcare institutions. Implementation results indicate that the iMAGE cloud can provide convenient, efficient, compatible, and secure medical image processing services in regional healthcare networks. The iMAGE cloud has been proven to be valuable in applications in the regional healthcare system, and it could have a promising future in the healthcare system worldwide.

Development of high nickel austenitic steels for the application to fast reactor cores, (I). Alloy design with the aid of the d-electrons concept

International Nuclear Information System (INIS)

Murata, Yoshinori; Morinaga, Masahiko; Yukawa, Natsuo; Ukai, Shigeharu; Nomura, Shigeo; Okuda, Takanari; Harada, Makoto

1999-01-01

The design of high nickel austenitic steels for the core materials of the fast reactors was performed following the d-electrons concept devised on the basis of molecular orbital calculations of transition-metal based alloys. In this design two calculated parameters are mainly utilized. The one is the d-orbital energy level (Md) of alloying transition elements, and the other is the bond order (Bo) that is a measure of the covalent bond strength between atoms. Using the Md-bar - Bo-bar phase stability diagram accurate prediction become possible for the phase stability of the austenite phase and 5% swelling at 140 dpa for nickel ions. Here, Md-bar and Bo-bar are the compositional average of Md and Bo parameters, respectively. On the basis of the phase stability diagram and preliminary experiments, guidelines for the alloy design of carbo-nitrides precipitated high nickel austenitic steels were constructed. Following the guidelines several new austenitic steels were designed for the fast reactors core material. (author)

Microstructure and properties of high chrome steel roller after laser surface melting

International Nuclear Information System (INIS)

Li Meiyan; Wang Yong; Han Bin; Zhao Weimin; Han Tao

2009-01-01

Laser surface melting of high chrome steels was achieved by a 5 kW continuous wave CO 2 laser. The microstructure of the laser surface-melted steels was investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffractometry, and the hardness profiles were determined by a Vickers hardness tester. The corrosion behavior in 3.5% NaCl solution was studied by electrochemical corrosion equipment. The large carbides of high chrome steels are completely dissolved and ultrafine dendrites of austenite with submicroscopic M 23 C 6 carbides precipitation are formed in the melted zone. The austenite in the melted zone has a high tempering stability. The corrosion resistance of the laser surface-melted steels is significantly improved due to the dissolution of carbides and the increase of the alloying elements in the solid solution as well as the large amount of austenite.

Sustainable Steel Carburization by Using Snack Packaging Plastic Waste as Carbon Resources

Directory of Open Access Journals (Sweden)

Songyan Yin

2018-01-01

Full Text Available In recent years, the research regarding waste conversion to resources technology has attracted growing attention with the continued increase of waste accumulation issues and rapid depletion of natural resources. However, the study, with respect to utilizing plastics waste as carbon resources in the metals industry, is still limited. In this work, an environmentally friendly approach to utilize snack packaging plastic waste as a valuable carbon resources for steel carburization is investigated. At high temperature, plastic waste could be subject to pyrolytic gasification and decompose into small molecular hydrocarbon gaseous products which have the potential to be used as carburization agents for steel. When heating some snack packaging plastic waste and a steel sample together at the carburization temperature, a considerable amount of carbon-rich reducing gases, like methane, could be liberated from the plastic waste and absorbed by the steel sample as a carbon precursor for carburization. The resulting carburization effect on steel was investigated by optical microscopy, scanning electron microscopy, electron probe microanalyzer, and X-ray photoelectron spectrometer techniques. These investigation results all showed that snack packaging plastic waste could work effectively as a valuable carbon resource for steel carburization leading to a significant increase of surface carbon content and the corresponding microstructure evolution in steel.

Electron beam welding of flanges with tubular shafts of steel 40KhNMA

International Nuclear Information System (INIS)

Leskov, G.I.; Zhivaga, L.I.; Shipitsyn, B.N.; Savichev, R.V.

1975-01-01

The results are presented of elaborating the technological process for the electron beam welding of flanges with a tube of the 40KhNMA steel and of investigation into the quality of the welded joints. A welded piece has been fabricated conforming to the technology suggested observing the parameters worked-out in the following sequence: assembling the piece; pre-welding of the edges in some points; welding; high tempering; welds quality control; removal of the seam reinforcement inside of the tube and the weld root to the depth of 2 mm; quenching; tempering; welds quality control; finishing. The welds quality control consists in visual inspection, ultrasonic testing, magnetic flaw detection, as well as X-ray and metallographic analyses. The mechanical properties are studied on notched samples cut out of the welded joints. The test results have shown that the mechanical properties of the welded joints meet the requirements on the same level with the base metal

Measuring agreement between decision support reminders: the cloud vs. the local expert

OpenAIRE

Dixon, Brian Edward; Simonaitis, Linas; Perkins, Susan M; Wright, Adam; Middleton, Blackford

2014-01-01

Background: A cloud-based clinical decision support system (CDSS) was implemented to remotely provide evidence-based guideline reminders in support of preventative health. Following implementation, we measured the agreement between preventive care reminders generated by an existing, local CDSS and the new, cloud-based CDSS operating on the same patient visit data. Methods: Electronic health record data for the same set of patients seen in primary care were sent to both the cloud-based web ser...

Stratocumulus Cloud Top Radiative Cooling and Cloud Base Updraft Speeds

Science.gov (United States)

Kazil, J.; Feingold, G.; Balsells, J.; Klinger, C.

2017-12-01

Cloud top radiative cooling is a primary driver of turbulence in the stratocumulus-topped marine boundary. A functional relationship between cloud top cooling and cloud base updraft speeds may therefore exist. A correlation of cloud top radiative cooling and cloud base updraft speeds has been recently identified empirically, providing a basis for satellite retrieval of cloud base updraft speeds. Such retrievals may enable analysis of aerosol-cloud interactions using satellite observations: Updraft speeds at cloud base co-determine supersaturation and therefore the activation of cloud condensation nuclei, which in turn co-determine cloud properties and precipitation formation. We use large eddy simulation and an off-line radiative transfer model to explore the relationship between cloud-top radiative cooling and cloud base updraft speeds in a marine stratocumulus cloud over the course of the diurnal cycle. We find that during daytime, at low cloud water path (CWP correlated, in agreement with the reported empirical relationship. During the night, in the absence of short-wave heating, CWP builds up (CWP > 50 g m-2) and long-wave emissions from cloud top saturate, while cloud base heating increases. In combination, cloud top cooling and cloud base updrafts become weakly anti-correlated. A functional relationship between cloud top cooling and cloud base updraft speed can hence be expected for stratocumulus clouds with a sufficiently low CWP and sub-saturated long-wave emissions, in particular during daytime. At higher CWPs, in particular at night, the relationship breaks down due to saturation of long-wave emissions from cloud top.

Cloud networking understanding cloud-based data center networks

CERN Document Server

Lee, Gary

2014-01-01

Cloud Networking: Understanding Cloud-Based Data Center Networks explains the evolution of established networking technologies into distributed, cloud-based networks. Starting with an overview of cloud technologies, the book explains how cloud data center networks leverage distributed systems for network virtualization, storage networking, and software-defined networking. The author offers insider perspective to key components that make a cloud network possible such as switch fabric technology and data center networking standards. The final chapters look ahead to developments in architectures

Heat treatments in a conventional steel to reproduce the microstructure of a nuclear grade steel

International Nuclear Information System (INIS)

Rosalio G, M.

2014-01-01

The ferritic steels used in the manufacture of pressurized vessels of Boiling Water Reactors (BWR) suffer degradation in their mechanical properties due to damage caused by the neutron fluxes of high energy bigger to a Mega electron volt (E> 1 MeV) generated in the reactor core. The materials with which the pressurized vessels of nuclear reactors cooled by light water are built correspond to low alloy ferritic steels. The effect of neutron irradiation on these steels is manifested as an increase in hardness, mechanical strength, with the consequent decrease in ductility, fracture toughness and an increase in temperature of ductile-brittle transition. The life of a BWR is 40 years, its design must be considered sufficient margin of safety because pressure forces experienced during operation, maintenance and testing of postulated accident conditions. It is necessary that under these conditions the vessel to behave ductile and likely to propagate a fracture is minimized. The vessels of light water nuclear reactors have a bainite microstructure. Specifically, the reactor vessels of the nuclear power plant of Laguna Verde (Veracruz, Mexico) are made of a steel Astm A-533, Grade B Class 1. At present they are carrying out some welding tests for the construction of a model of a BWR, however, to use nuclear grade steel such as Astm A-533 to carry out some of the welding tests, is very expensive; perform these in a conventional material provides basic information. Although the microstructure present in the conventional material does not correspond exactly to the degree of nuclear material, it can take of reference. Therefore, it is proposed to conduct a pilot study to establish the thermal treatment that reproduces the microstructure of nuclear grade steel, in conventional steel. The resulting properties of the conventional steel samples will be compared to a JRQ steel, that is a steel Astm A-533, Grade B Class 1, provided by IAEA. (Author)

How to build a cloud chamber?; Comment realiser une chambre a bouillard?

Energy Technology Data Exchange (ETDEWEB)

Mariaud, C. [Lycee Rene Descartes, 37000 Tours (France)

2012-01-15

The cloud chamber had its heyday in the first half of last century and allowed the discovery of new particles such as the anti-electron, the muon and the neutral and the charged kaon. The bubble chamber replaced it in the mid fifties. This article recalls the principle of the cloud chamber and shows, in a detailed way, how to proceed to build one with on-the-shelf materials. This design is based on the use of isopropanol whose liquefaction through the form of droplets materializes the track of the particle and on the use of combined Peltier cells (instead of CO{sub 2} snow) to cool the chamber. This cloud chamber has been successfully used in schools to observe particles mainly electrons, alphas and muons generated by cosmic rays. (A.C.)

X-ray impact induced desorption of gases from stainless steel surfaces

International Nuclear Information System (INIS)

Brumbach, S.; Kaminsky, M.

1975-01-01

During the operation of plasma devices the interaction of energetic photons with surfaces can cause gas release by photodesorption, and thereby contribute to plasma contamination. Measurements of gases released from stainless steel surfaces were made in an ultrahigh vacuum environment using x-rays characteristic for a tungsten target bremsstrahlung spectrum for electron energies varying from 15 to 50 keV. The predominant gas species observed mass spectrometically are CO 2 (m/e = 44), CO (m/e = 28), and O 2 (m/e = 32). Mean quantum yields for the release of these species from stainless steel were determined. For example, for fresh stainless steel surfaces irradiated by x-rays produced by 50 keV electrons, a mean quantum yield for molecular CO 2 release of 3 x 10 -4 molecules per photons in a bremsstrahlung spectrum at 50 keV electron energy was observed. Based on such a quantum yield an outgassing rate was determined

Proposal to negotiate a collaboration agreement for the design and prototyping of a machine for laser treatment of metallic vacuum chamber walls for electron cloud mitigation at the High Luminosity LHC

CERN Document Server

2016-01-01

Proposal to negotiate a collaboration agreement for the design and prototyping of a machine for laser treatment of metallic vacuum chamber walls for electron cloud mitigation at the High Luminosity LHC

Nanostructuring steel for injection molding tools

International Nuclear Information System (INIS)

Al-Azawi, A; Smistrup, K; Kristensen, A

2014-01-01

The production of nanostructured plastic items by injection molding with ridges down to 400 nm in width, which is the smallest line width replicated from nanostructured steel shims, is presented. Here we detail a micro-fabrication method where electron beam lithography, nano-imprint lithography and ion beam etching are combined to nanostructure the planar surface of a steel wafer. Injection molded plastic parts with enhanced surface properties, like anti-reflective, superhydrophobic and structural colors can be achieved by micro- and nanostructuring the surface of the steel molds. We investigate the minimum line width that can be realized by our fabrication method and the influence of etching angle on the structure profile during the ion beam etching process. Trenches down to 400 nm in width have been successfully fabricated into a 316 type electro-polished steel wafer. Afterward a plastic replica has been produced by injection molding with good structure transfer fidelity. Thus we have demonstrated that by utilizing well-established fabrication techniques, nanostructured steel shims that are used in injection molding, a technique that allows low cost mass fabrication of plastic items, are produced. (paper)

Mobile healthcare information management utilizing Cloud Computing and Android OS.

Science.gov (United States)

Doukas, Charalampos; Pliakas, Thomas; Maglogiannis, Ilias

2010-01-01

Cloud Computing provides functionality for managing information data in a distributed, ubiquitous and pervasive manner supporting several platforms, systems and applications. This work presents the implementation of a mobile system that enables electronic healthcare data storage, update and retrieval using Cloud Computing. The mobile application is developed using Google's Android operating system and provides management of patient health records and medical images (supporting DICOM format and JPEG2000 coding). The developed system has been evaluated using the Amazon's S3 cloud service. This article summarizes the implementation details and presents initial results of the system in practice.