Neutron-induced hydrogen and helium production in iron

Energy Technology Data Exchange (ETDEWEB)

Haight, Robert C.

2004-01-01

In support of the Advanced Fuel Cycle Initiative, cross sections for hydrogen and helium production by neutrons are being investigated on structural materials from threshold to 100 MeV with the continuous-in-energy spallation neutron source at the Los Alamos Neutron Science Center (LANSCE). The present measurements are for elemental iron. The results are compared with values from the ENDF/B-VI library and its extension with LA150 evaluations. For designs in the Advanced Fuel Cycle Initiative, structural materials will be subjected to very large fluences of neutrons, and the selection of these materials will be guided by their resistance to radiation damage. The macroscopic effects of radiation damage result both from displacement of atoms in the materials as well as nuclear transmutation. We are studying the production of hydrogen and helium by neutrons, because these gases can lead to significant changes in materials properties such as embrittlement and swelling. Our experiments span the full range from threshold to 100 MeV. The lower neutron energies are those characteristic of fission neutrons, whereas the higher energies are relevant for accelerator-based irradiation test facilities. Results for the nickel isotopes, {sup 58,60}Ni, have been reported previously. The present studies are on natural iron.

Flash-induced fading: Dependence on colour and shape similarity

NARCIS (Netherlands)

Vergeer, M.L.T.; Lier, R.J. van

2005-01-01

We investigated the effects of perceptual grouping by colour and shape similarity on flash-induced perceptual fading. This flash-induced fading effect (Kanai et al, 2003 Journal of Cognitive Neuroscience 15 664 - 672) is considered as a time-locked variant of the Troxler effect. In the original

Helium production in reactor materials

International Nuclear Information System (INIS)

Lippincott, E.P.; McElroy, W.N.; Farrar, H. IV.

1975-02-01

Comparisons of integral helium production measurements with predictions based on ENDF/B Version IV cross sections have been made. It is concluded that an ENDF/B helium production cross section file should be established in order to ensure a complete and consistent cross section evaluation to meet accuracies required for LMFBR, CTR, and LWR applications. (U.S.)

Low-mass stars with mass loss and low-luminosity carbon star formation

International Nuclear Information System (INIS)

Boothroyd, A.I.

1987-01-01

The effects of large carbon enrichments in static stellar envelopes were investigated, using new Los Alamos opacities (including low-temperature carbon and molecular opacities) and including carbon ionizations. To search for the production of low-mass,low-luminosity carbon stars, detailed stellar evolutionary computations were carried out for a grid of low-mass stars of two different metallicities. The stars were evolved from the main sequence through all intermediate stages and through helium-shell flashes on the asymptotic giant branch. The effects of the latest nuclear reaction rates, the new Los Alamos opacities, Reimers-type wind mass loss, and detailed treatment of convection and semi-convection were investigated. Two low-luminosity carbon stars were achieved, in excellent agreement with observations. Conditions favoring dredge-up (and thus carbon-star production) include a reasonably large convective mixing length, low metallicity, relatively large envelope mass, and high flash strength. Mass loss was of major importance, tending to oppose dredge-up; the total mass-loss amounts inferred from observations suffice to prevent formation of high-mass, high-luminosity carbon stars

THE CIRCUMSTELLAR ENVIRONMENT OF R CORONAE BOREALIS: WHITE DWARF MERGER OR FINAL-HELIUM-SHELL FLASH?

International Nuclear Information System (INIS)

Clayton, Geoffrey C.; Andrews, J. E.; Sugerman, Ben E. K.; Adam Stanford, S.; Whitney, B. A.; Honor, J.; Babler, B.; Barlow, M. J.; Gordon, K. D.; Bond, Howard E.; Matsuura, M.; Geballe, T. R.; De Marco, O.; Lawson, W. A.; Sibthorpe, B.; Olofsson, G.; Polehampton, E.; Gomez, H. L.; Hargrave, P. C.; Ivison, R. J.

2011-01-01

In 2007, R Coronae Borealis (R CrB) went into a historically deep and long decline. In this state, the dust acts like a natural coronagraph at visible wavelengths, allowing faint nebulosity around the star to be seen. Imaging has been obtained from 0.5 to 500 μm with Gemini/GMOS, Hubble Space Telescope/WFPC2, Spitzer/MIPS, and Herschel/SPIRE. Several of the structures around R CrB are cometary globules caused by wind from the star streaming past dense blobs. The estimated dust mass of the knots is consistent with their being responsible for the R CrB declines if they form along the line of sight to the star. In addition, there is a large diffuse shell extending up to 4 pc away from the star containing cool 25 K dust that is detected all the way out to 500 μm. The spectral energy distribution of R CrB can be well fitted by a 150 AU disk surrounded by a very large diffuse envelope which corresponds to the size of the observed nebulosity. The total masses of the disk and envelope are 10 –4 and 2 M ☉ , respectively, assuming a gas-to-dust ratio of 100. The evidence pointing toward a white dwarf merger or a final-helium-shell flash origin for R CrB is contradictory. The shell and the cometary knots are consistent with a fossil planetary nebula. Along with the fact that R CrB shows significant lithium in its atmosphere, this supports the final-helium-shell flash. However, the relatively high inferred mass of R CrB and its high fluorine abundance support a white dwarf merger.

SNS Central Helium Liquefier spare Carbon Bed installation and commissioning

Energy Technology Data Exchange (ETDEWEB)

Degraff, Brian D. [ORNL; Howell, Matthew P. [ORNL; Kim, Sang-Ho [ORNL; Neustadt, Thomas S. [ORNL

2017-07-01

The Spallation Neutron Source (SNS) Central Helium Liquefier (CHL) at Oak Ridge National Laboratory (ORNL) has been without major operations downtime since operations were started back in 2006. This system utilizes a vessel filled with activated carbon as the final major component to remove oil vapor from the compressed helium circuit prior to insertion into the system's cryogenic cold box. The need for a spare carbon bed at SNS due to the variability of carbon media lifetime calculation to adsorption efficiency will be discussed. The fabrication, installation and commissioning of this spare carbon vessel will be presented. The novel plan for connecting the spare carbon vessel piping to the existing infrastructure will be presented.

Friction and wear studies of graphite and a carbon-carbon composite in air and in helium

International Nuclear Information System (INIS)

Li, C.C.; Sheehan, J.E.

1980-10-01

Sliding friction and wear tests were conducted on a commercial isotropic graphite and a carbon-carbon composite in air, purified helium, and a helium environment containing controlled amounts of impurities simulating the primary coolant chemistry of a high-temperature gas-cooled reactor (HTGR). The friction and wear characteristics of the materials investigated were stable and were found to be very sensitive to the testing temperature. In general, friction and wear decreased with increasing temperature in the range from ambient to 950 0 C. This temperature dependence is concluded to be due to chemisorption of impurities to form lubricating films and oxidation at higher temperatures, which reduce friction and wear. Graphite and carbon-carbon composites are concluded to be favorable candidate materials for high-temperature sliding service in helium-cooled reactors

Neutron-induced helium implantation in GCFR cladding

International Nuclear Information System (INIS)

Yamada, H.; Poeppel, R.B.; Sevy, R.H.

1980-10-01

The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10 10 He/cm 2 .s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 μm, more than 99% of helium particles are implanted in the first 2-μm-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding

Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

International Nuclear Information System (INIS)

Pentlehner, D.; Slenczka, A.

2015-01-01

Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

THE CIRCUMSTELLAR ENVIRONMENT OF R CORONAE BOREALIS: WHITE DWARF MERGER OR FINAL-HELIUM-SHELL FLASH?

Energy Technology Data Exchange (ETDEWEB)

Clayton, Geoffrey C.; Andrews, J. E. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Sugerman, Ben E. K. [Department of Physics and Astronomy, Goucher College, 1021 Dulaney Valley Rd., Baltimore, MD 21204 (United States); Adam Stanford, S. [IGPP, Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Whitney, B. A. [Space Science Institute, 4750 Walnut St. Suite 205, Boulder, CO 80301 (United States); Honor, J.; Babler, B. [Department of Astronomy, 475 North Charter St., University of Wisconsin, Madison, WI 53706 (United States); Barlow, M. J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Gordon, K. D.; Bond, Howard E.; Matsuura, M. [STScI, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Geballe, T. R. [Gemini Observatory, 670 N. A' ohoku Place, Hilo, HI 96720 (United States); De Marco, O. [Department of Physics, Macquarie University, Sydney, NSW 2109 (Australia); Lawson, W. A. [School of PEMS, University of New South Wales, ADFA, P.O. Box 7916, Canberra, ACT 2610 (Australia); Sibthorpe, B. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Olofsson, G. [Department of Astronomy, Stockholm University, AlbaNova University Center, Roslagstullsbacken 21, SE-10691 Stockholm (Sweden); Polehampton, E. [Space Science and Technology Department, Rutherford Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Gomez, H. L.; Hargrave, P. C. [School of Physics and Astronomy, Cardiff University, 5 The Parade, Cardiff, Wales CF24 3YB (United Kingdom); Ivison, R. J., E-mail: gclayton@phys.lsu.edu, E-mail: jandrews@phys.lsu.edu, E-mail: ben.sugerman@goucher.edu, E-mail: stanford@physics.ucdavis.edu, E-mail: bwhitney@spacescience.org, E-mail: jhonor@astro.wisc.edu, E-mail: brian@astro.wisc.edu, E-mail: mjb@star.ucl.ac.uk [UK Astronomy Technology Centre, ROE, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); and others

2011-12-10

In 2007, R Coronae Borealis (R CrB) went into a historically deep and long decline. In this state, the dust acts like a natural coronagraph at visible wavelengths, allowing faint nebulosity around the star to be seen. Imaging has been obtained from 0.5 to 500 {mu}m with Gemini/GMOS, Hubble Space Telescope/WFPC2, Spitzer/MIPS, and Herschel/SPIRE. Several of the structures around R CrB are cometary globules caused by wind from the star streaming past dense blobs. The estimated dust mass of the knots is consistent with their being responsible for the R CrB declines if they form along the line of sight to the star. In addition, there is a large diffuse shell extending up to 4 pc away from the star containing cool 25 K dust that is detected all the way out to 500 {mu}m. The spectral energy distribution of R CrB can be well fitted by a 150 AU disk surrounded by a very large diffuse envelope which corresponds to the size of the observed nebulosity. The total masses of the disk and envelope are 10{sup -4} and 2 M{sub Sun }, respectively, assuming a gas-to-dust ratio of 100. The evidence pointing toward a white dwarf merger or a final-helium-shell flash origin for R CrB is contradictory. The shell and the cometary knots are consistent with a fossil planetary nebula. Along with the fact that R CrB shows significant lithium in its atmosphere, this supports the final-helium-shell flash. However, the relatively high inferred mass of R CrB and its high fluorine abundance support a white dwarf merger.

The Mechanism of Helium-Induced Preconditioning: A Direct Role for Nitric Oxide in Rabbits

Science.gov (United States)

Pagel, Paul S.; Krolikowski, John G.; Pratt, Phillip F.; Shim, Yon Hee; Amour, Julien; Warltier, David C.; Weihrauch, Dorothee

2008-01-01

BACKGROUND Helium produces preconditioning against myocardial infarction by activating prosurvival signaling, but whether nitric oxide (NO) generated by endothelial NO synthase plays a role in this phenomenon is unknown. We tested the hypothesis that NO mediates helium-induced cardioprotection in vivo. METHODS Rabbits (n = 62) instrumented for hemodynamic measurement were subjected to a 30-min left anterior descending coronary artery occlusion and 3 h reperfusion, and received 0.9% saline (control) or three cycles of 70% helium–30% oxygen administered for 5 min interspersed with 5 min of an air–oxygen mixture before left anterior descending coronary artery occlusion in the absence or presence of pretreatment with the nonselective NOS inhibitor N-nitro-l-arginine methyl ester (L-NAME; 10 mg/kg), the selective inducible NOS inhibitor aminoguanidine hydrochloride (AG; 300 mg/kg), or selective neuronal NOS inhibitor 7-nitroindazole (7-NI; 50 mg/kg). In additional rabbits, the fluorescent probe 4,5-diaminofluroscein diacetate (DAF-2DA) and confocal laser microscopy were used to detect NO production in the absence or presence of helium with or without L-NAME pretreatment. RESULTS Helium reduced (P < 0.05) infarct size (24% ± 4% of the left ventricular area at risk; mean ± sd) compared with control (46% ± 3%). L-NAME, AG, and 7-NI did not alter myocardial infarct size when administered alone. L-NAME, but not 7-NI or AG, abolished helium-induced cardioprotection. Helium enhanced DAF-2DA fluorescence compared with control (26 ± 8 vs 15 ± 5 U, respectively). Pretreatment with L-NAME abolished these helium-induced increases in DAF-2DA fluorescence. CONCLUSIONS The results indicate that cardioprotection by helium is mediated by NO that is probably generated by endothelial NOS in vivo. PMID:18713880

Characteristics of an activated carbon monolith for a helium adsorption compressor

NARCIS (Netherlands)

Lozano-Castello, D.; Jorda-Beneyto, M.; Cazorla-Amoros, D.; Linares-Solano, A.; Burger, Johannes Faas; ter Brake, Hermanus J.M.; Holland, Herman J.

2010-01-01

An activated carbon monolith (ACM) with a high helium adsorption/desorption capacity, high density, low pressure drop, low thermal expansion and good mechanical properties was prepared and applied successfully in a helium adsorption compressor as a part of a 4.5 K sorption cooler. The activated

Helium induces preconditioning in human endothelium in vivo

NARCIS (Netherlands)

Smit, Kirsten F.; Oei, Gezina T. M. L.; Brevoord, Daniel; Stroes, Erik S.; Nieuwland, Rienk; Schlack, Wolfgang S.; Hollmann, Markus W.; Weber, Nina C.; Preckel, Benedikt

2013-01-01

Helium protects myocardium by inducing preconditioning in animals. We investigated whether human endothelium is preconditioned by helium inhalation in vivo. Forearm ischemia-reperfusion (I/R) in healthy volunteers (each group n = 10) was performed by inflating a blood pressure cuff for 20 min.

Stars with shell energy sources. Part 1. Special evolutionary code

International Nuclear Information System (INIS)

Rozyczka, M.

1977-01-01

A new version of the Henyey-type stellar evolution code is described and tested. It is shown, as a by-product of the tests, that the thermal time scale of the core of a red giant approaching the helium flash is of the order of the evolutionary time scale. The code itself appears to be a very efficient tool for investigations of the helium flash, carbon flash and the evolution of a white dwarf accreting mass. (author)

Parietal disruption alters audiovisual binding in the sound-induced flash illusion.

Science.gov (United States)

Kamke, Marc R; Vieth, Harrison E; Cottrell, David; Mattingley, Jason B

2012-09-01

Selective attention and multisensory integration are fundamental to perception, but little is known about whether, or under what circumstances, these processes interact to shape conscious awareness. Here, we used transcranial magnetic stimulation (TMS) to investigate the causal role of attention-related brain networks in multisensory integration between visual and auditory stimuli in the sound-induced flash illusion. The flash illusion is a widely studied multisensory phenomenon in which a single flash of light is falsely perceived as multiple flashes in the presence of irrelevant sounds. We investigated the hypothesis that extrastriate regions involved in selective attention, specifically within the right parietal cortex, exert an influence on the multisensory integrative processes that cause the flash illusion. We found that disruption of the right angular gyrus, but not of the adjacent supramarginal gyrus or of a sensory control site, enhanced participants' veridical perception of the multisensory events, thereby reducing their susceptibility to the illusion. Our findings suggest that the same parietal networks that normally act to enhance perception of attended events also play a role in the binding of auditory and visual stimuli in the sound-induced flash illusion. Copyright © 2012 Elsevier Inc. All rights reserved.

THE GREEN BANK TELESCOPE H II REGION DISCOVERY SURVEY. IV. HELIUM AND CARBON RECOMBINATION LINES

Energy Technology Data Exchange (ETDEWEB)

Wenger, Trey V.; Bania, T. M. [Astronomy Department, 725 Commonwealth Avenue, Boston University, Boston, MA 02215 (United States); Balser, Dana S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475 (United States); Anderson, L. D. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States)

2013-02-10

The Green Bank Telescope H II Region Discovery Survey (GBT HRDS) found hundreds of previously unknown Galactic regions of massive star formation by detecting hydrogen radio recombination line (RRL) emission from candidate H II region targets. Since the HRDS nebulae lie at large distances from the Sun, they are located in previously unprobed zones of the Galactic disk. Here, we derive the properties of helium and carbon RRL emission from HRDS nebulae. Our target sample is the subset of the HRDS that has visible helium or carbon RRLs. This criterion gives a total of 84 velocity components (14% of the HRDS) with helium emission and 52 (9%) with carbon emission. For our highest quality sources, the average {sup 4}He{sup +}/H{sup +} abundance ratio by number, (y {sup +}), is 0.068 {+-} 0.023(1{sigma}). This is the same ratio as that measured for the sample of previously known Galactic H II regions. Nebulae without detected helium emission give robust y {sup +} upper limits. There are 5 RRL emission components with y {sup +} less than 0.04 and another 12 with upper limits below this value. These H II regions must have either a very low {sup 4}He abundance or contain a significant amount of neutral helium. The HRDS has 20 nebulae with carbon RRL emission but no helium emission at its sensitivity level. There is no correlation between the carbon RRL parameters and the 8 {mu}m mid-infrared morphology of these nebulae.

Helium production in mixed spectrum reactor-irradiated pure elements

International Nuclear Information System (INIS)

Kneff, D.W.; Oliver, B.M.; Skowronski, R.P.

1986-01-01

The objectives of this work are to apply helium accumulation neutron dosimetry to the measurement of neutron fluences and energy spectra in mixed-spectrum fission reactors utilized for fusion materials testing, and to measure helium generation rates of materials in these irradiation environments. Helium generation measurements have been made for several Fe, Cu Ti, Nb, Cr, and Pt samples irradiated in the mixed-spectrum High Flux Isotope Reactor (HFIR) and Oak Ridge Research Reactor (ORR) at the Oak Ridge National Laboratory. The results have been used to integrally test the ENDF/B-V Gas Production File, by comparing the measurements with helium generation predictions made by Argonne National Laboratory using ENDF/B-V cross sections and adjusted reactor spectra. The comparisons indicate consistency between the helium measurements and ENDF/B-V for iron, but cross section discrepancies exist for helium production by fast neutrons in Cu, Ti, Nb, and Cr (the latter for ORR). The Fe, Cu, and Ti work updates and extends previous measurements

Experimental and numerical investigations on flashing-induced instabilities in a single channel

Energy Technology Data Exchange (ETDEWEB)

Marcel, Christian P.; Rohde, M.; Van Der Hagen, T.H.J.J. [Department of Physics of Nuclear Reactors, Delft University of Technology (TUDelft), Delft, 2629 JB (Netherlands)

2009-11-15

During the start-up phase, natural circulation BWRs (NC-BWRs) need to be operated at low pressure conditions. Such conditions favor flashing-induced instabilities due to the large hydrostatic pressure drop induced by the tall chimney. Moreover, in novel NC-BWR designs the steam separation is performed in the steam separators which create large pressure drops at the chimney outlet, which effect on stability has not been investigated yet. In this work, flashing-induced oscillations occurring in a tall, bottom heated channel are numerically investigated by using a simple linear model with three regions and an accurate implementation for estimating the water properties. The model is used to investigate flashing-induced instabilities in a channel for different values of the core inlet friction value. The results are compared with experiments obtained by using the CIRCUS facility at the same conditions, showing a good agreement. In addition, the experiments on flashing-induced instabilities are presented in a novel manner allowing visualizing new details of the phenomenon numerical stability investigations on the effect of the friction distribution are also done. It is found that by increasing the total restriction in the channel the system is destabilized. In addition, the chimney outlet restriction has a stronger destabilizing effect than the core inlet restriction. A stable two-phase region is observed prior to the instabilities in the experiments and the numerical simulations which may help to pressurize the vessel of NC-BWRs and thus reducing the effects of flashing instabilities during start-up. (author)

A comparison of hydrogen vs. helium glow discharge effects on fusion device first-wall conditioning

International Nuclear Information System (INIS)

Dylla, H.F.

1989-09-01

Hydrogen- and deuterium-fueled glow discharges are used for the initial conditioning of magnetic fusion device vacuum vessels following evacuation from atmospheric pressure. Hydrogenic glow discharge conditioning (GDC) significantly reduces the near-surface concentration of simple adsorbates, such as H 2 O, CO, and CH 4 , and lowers ion-induced desorption coefficients by typically three orders of magnitude. The time evolution of the residual gas production observed during hydrogen-glow discharge conditioning of the carbon first-wall structure of the TFTR device is similar to the time evolution observed during hydrogen GDC of the initial first-wall configuration in TFTR, which was primarily stainless steel. Recently, helium GDC has been investigated for several wall-conditioning tasks on a number of tokamaks including TFTR. Helium GDC shows negligible impurity removal with stainless steel walls. For impurity conditioning with carbon walls, helium GDC shows significant desorption of H 2 O, CO, and CO 2 ; however, the total desorption yield is limited to the monolayer range. In addition, helium GDC can be used to displace hydrogen isotopes from the near-surface region of carbon first-walls in order to lower hydrogenic retention and recycling. 38 refs., 6 figs

Performance of carbon-based hot frit substrates: I, Low pressure helium and hydrogen testing

International Nuclear Information System (INIS)

Barletta, R.; Adams, J.; Svandrlik, J.; Powell, J.R.

1993-07-01

The performance of various carbon-based materials in flowing, high-temperature helium and hydrogen is described. These materials which are candidate hot frit substrates for possible application in a PBR include various grades of graphite, carbon-carbon and vitreous carbon. Vitreous carbon showed extremely good performance in helium, while that of the various graphite grades was quite variable and, in some cases, poor. Purified grades performed better than unpurified grades, but in all cases large sample-to-sample variations in weight loss were observed. For carbon-carbon samples, the performance was intermediate. Since the weight loss in these samples was in large measure due to the loss of the densification media, improvements in the performance of carbon-carbon may be possible. With respect to the performance in hydrogen, high weight losses were observed, re-enforcing the need for coating carbon-based materials for service in a flowing hydrogen environment

New technique for enhancing helium production in ferritic materials

International Nuclear Information System (INIS)

Greenwood, L.R.; Graczyk, D.G.; Kneff, D.W.

1987-10-01

Analyses of iron samples irradiated up to 10 27 n/m 2 in HFIR found more helium than was expected from fast neutron reactions at high neutron fluences. The helium excess increases systematically with neutron exposure, suggesting a transmutation-driven process. The extra helium may be produced in two different ways, either by fast neutron reactions on the transmuted isotopes of iron or by a thermal neutron reaction with the radioactive isotope 55 Fe. Radiometric and mass spectrometric measurements of the iron isotopes composing the irradiated samples have been used to determine limits on the cross sections for each process. Either of these processes can be used to enhance helium production in ferritic materials during irradiations in mixed-spectrum reactors by isotopically enriching the samples. Further work is needed to clarify the reaction mechanisms and helium production cross sections. Our measurements determined the thermal neutron total absorption cross section of 55 Fe to be 13.2 +- 2.1 barns. 16 refs., 3 figs., 3 tabs

Characterization of carbon nanolayers flash evaporated on PET and PTFE

Czech Academy of Sciences Publication Activity Database

Švorčík, V.; Hubička, T.; Slepička, P.; Siegel, J.; Kolská, Z.; Bláhová, O.; Macková, Anna; Hnatowicz, Vladimír

2009-01-01

Roč. 47, č. 7 (2009), s. 1770-1778 ISSN 0008-6223 R&D Projects: GA MŠk(CZ) LC06041; GA ČR GA106/09/0125 Institutional research plan: CEZ:AV0Z10480505 Keywords : carbon nano-layers * flash evaporation * PET Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 4.504, year: 2009

Out-of-phase flashing induced instabilities in CIRCUS facility

Energy Technology Data Exchange (ETDEWEB)

Christian Pablo Marcel; Van der Hagen, T.H.J.J. [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

2005-07-01

Full text of publication follows: Flashing-induced instabilities are very important during the startup phase of natural-circulation boiling water reactors. To study this type of instability an axial fully scaled facility named CIRCUS was constructed. Experiments at low power and low pressure (typical startup conditions) are carried out on this steam/water natural circulation loop with two parallel risers. A detailed measurement of the void-fraction profile is possible by using needle-probes and the use of glass tubes for the riser and core sections allow to use optical techniques for velocity measurements. The flashing and the mechanism of flashing-induced instabilities are analyzed paying special attention on the strong coupling effect between the two riser channels. It is clear from the experiments that the out-of-phase instability is much more susceptible to occur than the in-phase instability in a system with two parallel risers. The instability region is found as soon as the operational boundary between single-phase and two-phase operation is crossed. The relation between the period of the oscillations and the fluid transient time is also investigated. The stability map constructed using this experimental data is also discussed. (authors)

Development of helium porosity near-by grain boundaries in nickel-carbon alloys

International Nuclear Information System (INIS)

Reutov, I.V.; Reutov, V.F.

1995-01-01

The peculiarities of development of helium porosity near grain boundaries in nickel with 0.002-0.065 at.% carbon uniformly doped with helium up to 2·10 -2 at.% in the process of post-irradiation isothermal annealing at 800 deg C for 1-50 hours are studied. It is stated that at this annealing temperature intensive nucleation and growth of bubbles are observed in near-boundary region whose width grows both with increase of annealing time and carbon content. The TEM studies have shown that in near-boundary zone itself the process of bubble growth is non-uniform: bubble size increases and their density decreases as the distance from grain boundary is increased. The effect observed is discussed from the point of view of formation of two zones with different level of swelling in a grain (near-by boundary and matrix) and consequently, hydrostatic stress as well conditioning the flux of vacancies and helium-vacancy complexes from matrix to grain boundary. 8 refs., 5 figs

Investigation of flashing-induced instabilities at Circus test facility with the code ATHLET

Energy Technology Data Exchange (ETDEWEB)

Schafer, F.; Manera, A. [Forschungzentrum Rossendorf e.V., Institute of Safety Research, P.O. Box 510119, D-01314 Dresden (Germany)]. E-mail: F.Schaefer@fz-rossendorf.de; A.Manera@fz-rossendorf.de

2006-07-01

The test facility CIRCUS (CIRculation Under Start-up) was built to study the start-up phase of a natural-circulation BWR. During the start-up,so-called flashing-induced instabilities can arise. These instabilities are induced by flashing (i.e., steam production in adiabatic conditions) of the coolant in the long riser section, which is placed above the core to enhance the flow rate. The flashing that occurs in the riser causes an imbalance between driving force and pressure losses in the natural-circulation loop, giving rise to flow oscillations. Within the European-Union 5th Framework Programme, a project, NACUSP (Natural circulation and stability performance of BWRs), has been started in December 2000, having as one of its main aims the understanding of the physics of the phenomena involved during the start-up phase of natural-circulation-cooled BWRs, providing a large experimental database and validating state-of-the-art thermo-hydraulic codes in the low-pressure, low-power operational region of these reactors. One part of this project deals with the modelling of selected CIRCUS tests using the thermo-hydraulic code ATHLET (Analysis of THermal-hydraulics of LEaks and Transients). This paper gives an overview about experiments and simulations. The code ATHLET is used to investigate the dynamic behaviour of the CIRCUS test facility and the results of the calculations are compared with the experimental data. (author)

Production of bio-oils from wood by flash pyrolysis; Herstellung von Bio-Oelen aus Holz in einer Flash-Pyrolyseanlage

Energy Technology Data Exchange (ETDEWEB)

Meier, D; Ollesch, T [Bundesforschungsanstalt fuer Forst- und Holzwirtschaft, Hamburg (Germany). Inst. fuer Holzchemie und Chemische Technologie des Holzes; Gerdes, C; Kaminsky, W [Hamburg Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMCh)

1998-09-01

Flash pyrolysis is a medium-temperature process (around 475 C) in which biomass is heated up rapidly in the absence of oxygen. The pyrolysis products are cooled down rapidly, condensing into a reddish-brown liquid with around half the calorific value of a conventional heating oil. In contrast to conventional charcoal production, flash pyrolysis is a modern process whose process parameters enure high liquid yields. Modern fluidized-bed reactors for flash pyrolysis of biomass tend to have high heating rates and short times of residue. In the `Hamburg process`, fluidized-bed reactors are used successfully for pyrolysis of plastics. A flash pyrolysis plant for biomass treatment was constructed in cooperation with Hamburg University with funds provided by the `Bundesstiftung Umwelt`. This contribution describes the first series of experiments, mass balances and oil analyses using beech wood as material to be pyrolyzed. (orig./SR) [Deutsch] Flash-Pyrolyse ist ein Mitteltemperatur-Prozess (ca. 475 C), in dem Biomasse unter Sauerstoffausschluss sehr schnell erhitzt wird. Die entstehenden Pyrolyseprodukte werden schnell abgekuehlt und kondensieren zu einer roetlich-braunen Fluessigkeit, die etwa die Haelfte des Heizwertes eines konventionellen Heizoeles besitzt. Flash-Pyrolyse ist, im Gegensatz zur konventionellen Holzverkohlung, ein modernes Verfahren, dessen spezielle Verfahrensparameter hohe Fluessigausbeuten ermoeglichen. Hohe Aufheizraten, verbunden mit kurzen Verweilzeiten, werden mit stationaeren Wirbelbettreaktoren erzielt die gegenwaertig vorwiegend fuer die Flash-Pyrolyse von Biomasse eingesetzt werden. Im `Hamburger Verfahren` haben sich Wirbelbettreaktoren im Bereich der Kunststoffpyrolyse bewaehrt. Daher wurde in Zusammenarbeit mit der Universitaet Hamburg und finanzieller Foerderung der Bundesstiftung Umwelt eine Flash-Pyrolyseanlage fuer Biomasse gebaut: In dieser Arbeit werden erste Versuchsreihen, Massenbilanzen und Oelanalysen aus der Pyrolyse von

Helium production by 10 MeV neutrons in iron, nickel and copper

International Nuclear Information System (INIS)

Haight, R.C.; Kneff, D.W.; Oliver, B.M.; Greenwood, L.R.; Vonach, H.

1994-01-01

Helium production cross sections for the elements Fe, Ni, and Cu and for the isotopes 56 Fe, 58 Ni and 60 Ni have been measured for 10-MeV neutrons. Samples were irradiated with an intense neutron source from the 1 H(t,n) reaction using a rotating gas cell. The generated helium was determined by isotope dilution gas mass spectrometry. Induced radioactivities and known cross sections were used together with calculations based on the source reaction to deduce the neutron fluence at each sample position. The results are in fair agreement with literature values for (n,α) cross sections measured by α-particle detection and integrated over the α-particle energies and angular distributions

Helium Adsorption on Carbon Nanotube Bundles with Different Diameters:. Molecular Dynamics Simulation

Science.gov (United States)

Majidi, R.; Karami, A. R.

2013-05-01

We have used molecular dynamics simulation to study helium adsorption capacity of carbon nanotube bundles with different diameters. Homogeneous carbon nanotube bundles of (8,8), (9,9), (10,10), (11,11), and (12,12) single walled carbon nanotubes have been considered. The results indicate that the exohedral adsorption coverage does not depend on the diameter of carbon nanotubes, while the endohedral adsorption coverage is increased by increasing the diameter.

The multiple ionization of helium induced by partially stripped carbon ions

International Nuclear Information System (INIS)

Cai Xiaohong; Chen Ximeng; Shen Ziyong

1996-01-01

The ratios of the double to single ionization cross sections of helium impacted by partially stripped C q+ ions (q = 1,2,3,4) in energy range of 1.5-7.5 MeV were measured by using the time of flight procedure. The n-body classical trajectory Monte Carlo calculation was carried out to get the Olson-Schlachter scaling. The single and double ionization cross sections of helium were obtained by comparing the cross section ratios of the present work with the Olson-Schlachter scaling

Preliminary Overview of a Helium Cooling System for the Secondary Helium Loop in VHTR-based SI Hydrogen Production Facilities

Energy Technology Data Exchange (ETDEWEB)

Shin, Youngjoon; Cho, Mintaek; Kim, Dahee; Lee, Taehoon; Lee, Kiyoung; Kim, Yongwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Nuclear hydrogen production facilities consist of a very high temperature gas-cooled nuclear reactor (VHTR) system, intermediate heat exchanger (IHX) system, and a sulfur-iodine (SI) thermochemical process. This study focuses on the coupling system between the IHX system and SI thermochemical process. To prevent the propagation of the thermal disturbance owing to the abnormal operation of the SI process components from the IHX system to the VHTR system, a helium cooling system for the secondary helium of the IHX is required. In this paper, the helium cooling system has been studied. The temperature fluctuation of the secondary helium owing to the abnormal operation of the SI process was then calculated based on the proposed coupling system model. Finally, the preliminary conceptual design of the helium cooling system with a steam generator and forced-draft air-cooled heat exchanger to mitigate the thermal disturbance has been carried out. A conceptual flow diagram of a helium cooling system between the IHX and SI thermochemical processes in VHTR-based SI hydrogen production facilities has been proposed. A helium cooling system for the secondary helium of the IHX in this flow diagram prevents the propagation of the thermal disturbance from the IHX system to the VHTR system, owing to the abnormal operation of the SI process components. As a result of a dynamic simulation to anticipate the fluctuations of the secondary helium temperature owing to the abnormal operation of the SI process components with a hydrogen production rate of 60 mol·H{sub 2}/s, it is recommended that the maximum helium cooling capacity to recover the normal operation temperature of 450 .deg. C is 31,933.4 kJ/s. To satisfy this helium cooling capacity, a U-type steam generator, which has a heat transfer area of 12 m{sup 2}, and a forced-draft air-cooled condenser, which has a heat transfer area of 12,388.67 m{sup 2}, are required for the secondary helium cooling system.

Interference of laser-induced resonances in the continuous structures of a helium atom

International Nuclear Information System (INIS)

Magunov, A I; Strakhova, S I

2003-01-01

Coherent effects in the interference of overlapping laser-induced resonances in helium atoms are considered. The simultaneous action of single-mode radiation of the 294-nm second harmonic of a cw dye laser and a 1064-nm Nd:YAG laser on helium atoms provides the overlap of two resonances induced by transitions from the 1s2s 1 S and 1s4s 1 S helium levels. The shape of the overlapping laser-induced resonances in the rotating-wave approximation is described by analytic expressions, which depend on the laser radiation intensities and the ratio of laser frequencies. (nonlinear optical phenomena)

Backward and forward electron emission induced by helium projectiles incident on thin carbon foils: Influence of charge changing processes

Energy Technology Data Exchange (ETDEWEB)

Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: nipauly@ulb.ac.be; Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

2007-03-15

The backward and forward electron emission yields {gamma} {sub B} and {gamma} {sub F} have been calculated by Monte Carlo simulations for helium (He{sup ++}, He{sup +} or He{sup 0}) ions incident on thin amorphous carbon foils with energies around the electronic stopping power maximum (0.2-2 MeV). Besides the direct excitation of target electrons by the incident projectile, we have taken into account the different charge changing processes (He{sup ++} {r_reversible} He{sup +} {r_reversible} He{sup 0}) undergone by the helium ion in the target. We discuss in particular the connection between the electron emission yield {gamma} and the electronic stopping power (dE/dx){sub e}. We compare our results with previously published experimental results.

Manufacturing cycle for pure neon-helium mixture production

International Nuclear Information System (INIS)

Batrakov, B.P.; Kravchenko, V.A.

1980-01-01

The manufacturing cycle for pure neon-helium mixture production with JA-300 nitrogen air distributing device has been developed. Gas mixture containing 2-3% of neon-helium mixture (the rest is mainly nitrogen 96-97%) is selected out of the cover of the JA-300 column condensator and enters the deflegmator under the 2.3-2.5 atm. pressure. The diflegmator presents a heat exchange apparatus in which at 78 K liquid nitrogen the condensation of nitrogen from the mixture of gases entering from the JA-300 column takes place. The enriched gas mixture containing 65-70% of neon-helium mixture and 30-35% of nitrogen goes out from the deflegmator. This enriched neon-helium mixture enters the gasgoeder for impure (65-70%) neon-helium mixture. Full cleaning of-neon helium mixture of nitrogen is performed by means of an adsorber. As adsorbent an activated coal has been used. Adsorption occurs at the 78 K temperature of liquid nitrogen and pressure P=0.1 atm. As activated coal cooled down to nitrogen temperature adsorbs nitrogen better than neon and helium, the nitrogen from the mixture is completely adsorbed. Pure neon-helium mixture from the adsorber comes into a separate gasgolder. In one campaign the cycle allows obtaining 2 m 3 of the mixture. The mixture contains 0.14% of nitrogen, 0.01% of oxygen and 0.06% of hydrogen

Measurement of helium production cross sections of iron for d-T neutrons by helium accumulation method

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Kanda, Yukinori; Nagae, Koji; Fujimoto, Toshihiro [Kyushu Univ., Fukuoka (Japan); Ikeda, Yujiro

1997-03-01

Helium production cross sections of Iron were measured by helium accumulation method for neutron energies from 13.5 to 14.9 MeV. Iron samples were irradiated with FNS, an intense d-T neutron source of JAERI. As the neutron energy varies according to the emission angle at the neutron source, the samples were set around the neutron source and were irradiated by neutrons of different energy depending on each sample position. The amount of helium produced in a sample was measured by Helium Atoms Measurement System at Kyushu University. The results of this work are in good agreement with other experimental data in the literature and also compared with the evaluated values in JENDL-3. (author)

Normal temporal binding window but no sound-induced flash illusion in people with one eye.

Science.gov (United States)

Moro, Stefania S; Steeves, Jennifer K E

2018-04-19

Integrating vision and hearing is an important way in which we process our rich sensory environment. Partial deprivation of the visual system from the loss of one eye early in life results in adaptive changes in the remaining senses (e.g., Hoover et al. in Exp Brain Res 216:565-74, 2012). The current study investigates whether losing one eye early in life impacts the temporal window in which audiovisual events are integrated and whether there is vulnerability to the sound-induced flash illusion. In Experiment 1, we measured the temporal binding window with a simultaneity judgement task where low-level auditory and visual stimuli were presented at different stimulus onset asynchronies. People with one eye did not differ in the width of their temporal binding window, but they took longer to make judgements compared to binocular viewing controls. In Experiment 2, we measured how many light flashes were perceived when a single flash was paired with multiple auditory beeps in close succession (sound induced flash illusion). Unlike controls, who perceived multiple light flashes with two, three or four beeps, people with one eye were not susceptible to the sound-induced flash illusion. In addition, they took no longer to respond compared to both binocular and monocular (eye-patched) viewing controls. Taken together, these results suggest that the lack of susceptibility to the sound-induced flash illusion in people with one eye cannot be accounted for by the width of the temporal binding window. These results provide evidence for adaptations in audiovisual integration due to the reduction of visual input from the loss of one eye early in life.

Defects induced by helium implantation in SiC

International Nuclear Information System (INIS)

Oliviero, E.; Barbot, J.F.; Declemy, A.; Beaufort, M.F.; Oliviero, E.

2008-01-01

SiC is one of the considered materials for nuclear fuel conditioning and for the fabrication of some core structures in future nuclear generation reactors. For the development of this advance technology, a fundamental research on this material is of prime importance. In particular, the implantation/irradiation effects have to be understood and controlled. It is with this aim that the structural alterations induced by implantation/irradiation in SiC are studied by different experimental techniques as transmission electron microscopy, helium desorption, X-ray diffraction and Rutherford backscattering spectrometry. In this work, the different types of defects induced by helium implantation in SiC, point or primary defects (obtained at low energy (∼100 eV) until spread defects (obtained at higher energy (until ∼2 MeV)) are exposed. The amorphization/recrystallization and swelling phenomena are presented too. (O.M.)

Linear series of stellar models. Pt. 4. Helium-carbon stars of 3.5Msub(o) and 1Msub(o)

International Nuclear Information System (INIS)

Kozlowski, M.; Paczynski, B.; Popova, K.

1973-01-01

One linear series of models for a star of 3.5Msub(o) and two linear series of models for a star of 1Msub(o) are constructed. Models consist of helium rich envelopes (Y = 0.97, Z = 0.03) and pure carbon cores, and they have a rectangular helium profile, Y(Msub(r)). The linear series for a star of 3.5Msub(o) begins on the normal branch of the helium main sequence and terminates on the normal branch of the carbon main sequence. This series has eight turning points at which the core mass attains a local extremum. One of the two linear series for a star of 1Msub(o) begins on the normal branch of the helium main sequence, terminates on the high density branch of the helium main sequence, and has one turning point. The second linear series for a star of 1Msub(o) begins on the normal branch of the carbon main sequence, terminates on the high density branch of the carbon main sequence, and has three turning points. Two such linear series may have a common bifurcation point for a star of about 1.26Msub(o). (author)

Physics Flash December 2016

Energy Technology Data Exchange (ETDEWEB)

Kippen, Karen Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). ADEPS Communications

2016-12-01

This is the December 2016 issue of Physics Flash, the newsletter of the Physics Division of Los Alamos National Laboratory (LANL). In this issue, the following topics are covered: Novel liquid helium technique to aid highly sensitive search for a neutron electrical dipole moment; Silverleaf: Prototype Red Sage experiments performed at Q-site; John L. Kline named 2016 APS Fellow; Physics students in the news; First Entropy Engine quantum random number generator hits the market; and celebrating service.

HEINBE; the calculation program for helium production in beryllium under neutron irradiation

International Nuclear Information System (INIS)

Shimakawa, Satoshi; Ishitsuka, Etsuo; Sato, Minoru

1992-11-01

HEINBE is a program on personal computer for calculating helium production in beryllium under neutron irradiation. The program can also calculate the tritium production in beryllium. Considering many nuclear reactions and their multi-step reactions, helium and tritium productions in beryllium materials irradiated at fusion reactor or fission reactor may be calculated with high accuracy. The calculation method, user's manual, calculated examples and comparison with experimental data were described. This report also describes a neutronics simulation method to generate additional data on swelling of beryllium, 3,000-15,000 appm helium range, for end-of-life of the proposed design for fusion blanket of the ITER. The calculation results indicate that helium production for beryllium sample doped lithium by 50 days irradiation in the fission reactor, such as the JMTR, could be achieved to 2,000-8,000 appm. (author)

Photochemically induced carbon dioxide production as a mechanism for carbon loss from plant litter in arid ecosystems

Science.gov (United States)

Brandt, L. A.; Bohnet, C.; King, J. Y.

2009-06-01

We investigated the potential for abiotic mineralization to carbon dioxide (CO2) via photodegradation to account for carbon (C) loss from plant litter under conditions typical of arid ecosystems. We exposed five species of grass and oak litter collected from arid and mesic sites to a factorial design of ultraviolet (UV) radiation (UV pass, UV block), and sterilization under dry conditions in the laboratory. UV pass treatments produced 10 times the amount of CO2 produced in UV block treatments. CO2 production rates were unaffected by litter chemistry or sterilization. We also exposed litter to natural solar radiation outdoors on clear, sunny days close to the summer solstice at midlatitudes and found that UV radiation (280-400 nm) accounted for 55% of photochemically induced CO2 production, while shortwave visible radiation (400-500 nm) accounted for 45% of CO2 production. Rates of photochemically induced CO2 production on a per-unit-mass basis decreased with litter density, indicating that rates depend on litter surface area. We found no evidence for leaching, methane production, or facilitation of microbial decomposition as alternative mechanisms for significant photochemically induced C loss from litter. We conclude that abiotic mineralization to CO2 is the primary mechanism by which C is lost from litter during photodegradation. We estimate that CO2 production via photodegradation could be between 1 and 4 g C m-2 a-1 in arid ecosystems in the southwestern United States. Taken together with low levels of litter production in arid systems, photochemical mineralization to CO2 could account for a significant proportion of annual carbon loss from litter in arid ecosystems.

Technique to eliminate helium induced weld cracking in stainless steels

International Nuclear Information System (INIS)

Chin-An Wang; Chin, B.A.

1992-01-01

Experiments have shown that Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 Mpa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials

RBE of heavy ions (carbon, neon, helium, proton) for acute cell death of pancreatic islet cells

International Nuclear Information System (INIS)

Tsubouchi, Susumu; Fukutsu, Kumiko; Itsukaichi, Hiromi

2003-01-01

At this fiscal year, only two times irradiation experiments with neon and helium beams were performed to obtain relative biological effectiveness (RBE) of heavy ions (carbon, neon, helium, proton) for acute cell death of pancreatic islet cells in vivo. First of all this project was designed to obtain RBE of 290 MeV carbon and 400 MeV neon beams in the high linear energy transfer (LET) region for acute cell death of pancreatic islets of golden hamster (Mesocricetus auratus) in the condition of in both in vivo and in vitro systems. As mentioned in previous report, in vitro system, however, resulted in ill success. This in vitro experiment was tentatively shelved for the time being. In return in vivo experiments for low LET region of neon beams (32.5 KeV/u), carbon beams (15.0 KeV/u) and helium beams (2 KeV/u) were performed in these two years. Last year these results together with those previously obtained for 200 KeV X-ray, 70 MeV proton, 290 MeV carbon (60 KeV/u), and neon (100 KeV/u) beams were reconsidered. At this year dose response relations (25, 50, 100, 150, and 200 Gy respectively) in acute cell death of pancreatic islets studied histologically after whole body irradiation of 3 weeks young male golden hamster with lower LET helium beams (2 KeV/u) and neon beams (32.5 KeV/u). Results indicated that mean cell lethal dose (Do) of helium beams (2 KeV/u) and neon beams (32.5 KeV/u) were 38 Gy and 49 Gy, respectively. Previously obtained Do data for 200 KeV x-ray, 70 MeV proton, 290 MeV carbon (15 KeV/u), 400 MeV neon (32.5 KeV/u), 290 MeV carbon (60 KeV/u), and 400 MeV neon (100 KeV/u) beams were 37 Gy, 38 Gy, 38 Gy, 49 Gy, 75 Gy, and 200 Gy, respectively. From these data estimated RBE of neon (100 KeV/u and 32.5 KeV/u), carbon (60 KeV/u and 15.0 KeV/u), 70 MeV proton and 150 MeV helium (2 KeV/u) beams were 0.19, 0.76, 0.49, 0.97, 0.97, 0.97, respectively. Therefore the order of RBE (or radiosensitivities) of islets cells with these various heavy ion beams was

Helium in inert matrix dispersion fuels

International Nuclear Information System (INIS)

Veen, A. van; Konings, R.J.M.; Fedorov, A.V.

2003-01-01

The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO 2 , MgAl 2 O 4 , MgO and Al 2 O 3 ) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 deg. C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur

Retention of gaseous fission products by pure and modified activated carbon

International Nuclear Information System (INIS)

Wilhelmova, L.; Cejnar, F.

1975-01-01

The results are reported of research into Czechoslovak-made activated carbon Desorex DB-2 and Supersorbon HS-1 and their retention properties. Krypton, xenon and helium of spectral purity were used in the investigation. The effect of surface impregnation was also studied on the retention efficiency of the activated carbon. It was found that the impregnation with alkali metal fluorides, such as RbF and CsF favourably affected the retention properties of the activated carbon as concerns gaseous fission products. (L.O.)

Helium production technology based on natural gas combustion and beneficial use of thermal energy

Directory of Open Access Journals (Sweden)

Nakoryakov Vladimir E.

2016-01-01

Full Text Available Helium is widely used in all industries, including power plant engineering. In recent years, helium is used in plants operating by the Brayton cycle, for example, in the nuclear industry. Using helium-xenon mixture in nuclear reactors has a number of advantages, and this area is rapidly developing. The hydrodynamics and mass transfer processes in single tubes with various cross-sections as well as in inter-channel space of heating tube bundle were studied at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. Currently, there is a strongest shortage in helium production. The main helium production method consists in the liquefaction of the natural gas and subsequent separation of helium from remaining gas with its further purification using membranes.

Terrestrial gamma ray flash production by lightning current pulses

OpenAIRE

İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

2017-01-01

Terrestrial gamma ray flashes (TGFs) are brief bursts of gamma rays observed by satellites, typically in coincidence with detectable lightning. We incorporate TGF observations and the key physics behind current TGF production theories with lightning physics to produce constraints on TGF production mechanisms. The combined constraints naturally suggest a mechanism for TGF production by current pulses in lightning leader channels. The mechanism involves local field enhancements due to charge re...

Increased Expression of CCN2 in the Red Flashing Light-Induced Myopia in Guinea Pigs

Directory of Open Access Journals (Sweden)

Hong Wang

2013-01-01

Full Text Available Visual environment plays an important role in the occurrence of myopia. We previously showed that the different flashing lights could result in distinct effects on the ocular growth and development of myopia. CCN2 has been reported to regulate various cellular functions and biological processes. However, whether CCN2 signaling was involved in the red flashing light-induced myopia still remains unknown. In the present study, we investigated the effects of the red flashing lights exposure on the refraction and axial length of the eyes in vivo and then evaluated their effects on the expression of CCN2 and TGF-β in sclera tissues. Our data showed that the eyes exposed to the red flashing light became more myopic with a significant increase of the axial length and decrease of the refraction. Both CCN2 and TGF-β, as well as p38 MAPK and PI3K, were highly expressed in the sclera tissues exposed to the red flashing light. Both CCN2 and TGF-β were found to have the same gene expression profile in vivo. In conclusion, our findings found that CCN2 signaling pathway plays an important role in the red flashing light-induced myopia in vivo. Moreover, our study establishes a useful animal model for experimental myopia research.

Flash Platform Examination

Science.gov (United States)

2011-03-01

than would be performed in software”[108]. Uro Tinic, one of the Flash player’s engineers, further clarifies exactly what Flash player 10 hardware...www.adobe.com/products/flashplayer/features/ (Access date: 28 Sep 2009). [109] Uro , T. What Does GPU Acceleration Mean? (online), http...133] Shorten, A. (2009), Design to Development: Flash Catalyst to Flash Builder, In Proceedings of Adobe Max 2009, Los Angeles, CA. 142 DRDC

Coupling a Supercritical Carbon Dioxide Brayton Cycle to a Helium-Cooled Reactor.

Energy Technology Data Exchange (ETDEWEB)

Middleton, Bobby [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pasch, James Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kruizenga, Alan Michael [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Walker, Matthew [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2016-01-01

This report outlines the thermodynamics of a supercritical carbon dioxide (sCO₂) recompression closed Brayton cycle (RCBC) coupled to a Helium-cooled nuclear reactor. The baseline reactor design for the study is the AREVA High Temperature Gas-Cooled Reactor (HTGR). Using the AREVA HTGR nominal operating parameters, an initial thermodynamic study was performed using Sandia's deterministic RCBC analysis program. Utilizing the output of the RCBC thermodynamic analysis, preliminary values of reactor power and of Helium flow rate through the reactor were calculated in Sandia's HelCO₂ code. Some research regarding materials requirements was then conducted to determine aspects of corrosion related to both Helium and to sCO₂ , as well as some mechanical considerations for pressures and temperatures that will be seen by the piping and other components. This analysis resulted in a list of materials-related research items that need to be conducted in the future. A short assessment of dry heat rejection advantages of sCO₂> Brayton cycles was also included. This assessment lists some items that should be investigated in the future to better understand how sCO₂ Brayton cycles and nuclear can maximally contribute to optimizing the water efficiency of carbon free power generation

Activated carbon from flash pyrolysis of eucalyptus residue

Directory of Open Access Journals (Sweden)

Grima-Olmedo C

2016-09-01

Full Text Available Forestry waste (eucalyptus sp was converted into activated carbon by initial flash pyrolysis followed carbonization and CO2 activation. These residues were obtained from a pilot plant in Spain that produces biofuel, the biochar represented 10–15% in weight. It was observed that the highest activation was achieved at a temperature of 800 °C, the specific surface increased with time but, on the contrary, high loss of matter was observed. At 600 °C, although there was an important increase of the specific surface and the volume of micropores, at this temperature it was observed that the activation time was not an influential parameter. Finally, at 400 °C it was observed that the activation process was not very significant. Assessing the average pore diameter it was found that the lowest value corresponded to the activation temperature of 600 °C, which indicated the development of microporosity. When the activation temperature increases up to 800 °C the pore diameter increased developing mesoporosity.

A novel approach to process carbonate samples for radiocarbon measurements with helium carrier gas

Energy Technology Data Exchange (ETDEWEB)

Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Fueloep, R.-H. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany); Hajdas, I. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Molnar, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Rethemeyer, J. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany)

2013-01-15

Most laboratories prepare carbonates samples for radiocarbon analysis by acid decomposition in evacuated glass tubes and subsequent reduction of the evolved CO{sub 2} to graphite in self-made reduction manifolds. This process is time consuming and labor intensive. In this work, we have tested a new approach for the preparation of carbonate samples, where any high-vacuum system is avoided and helium is used as a carrier gas. The liberation of CO{sub 2} from carbonates with phosphoric acid is performed in a similar way as it is often done in stable isotope ratio mass spectrometry where CO{sub 2} is released with acid in septum sealed tube under helium atmosphere. The formed CO{sub 2} is later flushed in a helium flow by means of a double-walled needle mounted from the tubes to the zeolite trap of the automated graphitization equipment (AGE). It essentially replaces the elemental analyzer normally used for the combustion of organic samples. The process can be fully automated from sampling the released CO{sub 2} in the septum-sealed tubes with a commercially available auto-sampler to the graphitization with the automated graphitization. The new method yields in low sample blanks of about 50000 years. Results of processed reference materials (IAEA-C2, FIRI-C) are in agreement with their consensus values.

Photosynthetic efficiency of Chlamydomonas reinhardtii in flashing light

NARCIS (Netherlands)

Vejrazka, C.; Janssen, M.G.J.; Streefland, M.; Wijffels, R.H.

2011-01-01

Efficient light to biomass conversion in photobioreactors is crucial for economically feasible microalgae production processes. It has been suggested that photosynthesis is enhanced in short light path photobioreactors by mixing-induced flashing light regimes. In this study, photosynthetic

Neutron induced alpha production from carbon between 18 and 22 MeV

International Nuclear Information System (INIS)

Stevens, A.P.

1976-10-01

Cross sections for neutron induced alpha production in carbon were measured at seventeen energies between 18 and 22 MeV, using a deuterated anthracene crystal as both target and detector. Pulse shape discrimination was employed to separate the alphas and elastically scattered deuterons from the other reaction products. Published (n,d) elastic scattering data were used as a standard to obtain the alpha production cross sections. Comparison with available measurements shows good agreement

Proposed ripplon induced weak localization of electrons over liquid helium

International Nuclear Information System (INIS)

Dahm, A.J.

1997-01-01

Ripplon induced weak localization is proposed for electrons on a liquid helium surface. Ripplon scattering is quasi-elastic, the ripplon are quasi-static relative to the electron velocity, and the relative change in occupation number of the ripplon state in a scattering event is small. Conditions for the observation of ripplon induced weak localization are calculated

Helium production cross section Measurement of Pb and Sn for 14.9 MeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Fujimoto, Toshihiro; Ozaki, Shuji; Muramasu, Masatomo; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori; Ikeda, Yujiro

1998-03-01

Helium production cross sections of lead and tin for 14.9 MeV neutrons were measured by helium accumulation method. Lead and tin samples were irradiated with FNS, an intense d-T neutron source of JAERI. The amount of helium produced in the samples by the neutron irradiation was measured with the Helium Atoms Measurement System (HAMS) at Kyushu University. As the samples contained a small amount of helium because of their small helium production cross sections at 14.9 MeV, the samples were evaporated by radiation from a tungsten filament to decrease background gases at helium measurement. Uncertainties of the present results were less than {+-}4.4%. The results were compared with other experimental data in the literature and also compared with the evaluated values in JENDL-3.2. (author)

Experimental study on cryogenic adsorption of methane by activated carbon for helium coolant purification of High-Temperature Gas-cooled Reactor

International Nuclear Information System (INIS)

Chang, Hua; Wu, Zong-Xin; Jia, Hai-Jun

2017-01-01

Highlights: • The cryogenic CH 4 adsorption on activated carbon was studied for design of HTGR. • The breakthrough curves at different conditions were analyzed by the MTZ model. • The CH 4 adsorption isotherm was fitted well by the Toth model and the D-R model. • The work provides valuable reference data for helium coolant purification of HTGR. - Abstract: The cryogenic adsorption behavior of methane on activated carbon was investigated for helium coolant purification of high-temperature gas-cooled reactor by using dynamic column breakthrough method. With helium as carrier gas, experiments were performed at −196 °C and low methane partial pressure range of 0–120 Pa. The breakthrough curves at different superficial velocities and different feed concentrations were measured and analyzed by the mass-transfer zone model. The methane single-component adsorption isotherm was obtained and fitted well by the Toth model and the Dubinin-Radushkevich model. The adsorption heat of methane on activated carbon was estimated. The cryogenic adsorption process of methane on activated carbon has been verified to be effective for helium coolant purification of high-temperature gas-cooled reactor.

A climate-change policy induced shift from innovations in carbon-energy production to carbon-energy savings

International Nuclear Information System (INIS)

Gerlagh, Reyer

2008-01-01

We develop an endogenous growth model with capital, labor and carbon-energy as production factors and three technology variables that measure accumulated innovations for carbon-energy production, carbon-energy savings, and neutral growth. All markets are complete and perfect, except for research, for which we assume that the marginal social benefits exceed the marginal private benefits by factor four. The model constants are calibrated so that the model reproduces the relevant global trends over the 1970-2000 period. The model contains a simple climate module, and is used to assess the impact of Induced Technological Change (ITC) for a policy that aims at a maximum level of atmospheric CO 2 concentration (450 ppmv). ITC is shown to reduce the required carbon tax by more than a factor 2, and to reduce costs of such a policy by half. When we do not constrain aggregate R and D expenditures to benchmark levels, costs are further reduced. Numerical simulations show that knowledge accumulation shifts from energy production to energy saving technology. We discuss reasons for differences between our results and earlier results reported in the literature. (author)

Simulation study of radiation damage induced by energetic helium nuclei

CERN Document Server

Hoang Dac Luc; Hoang Dac Dat

2003-01-01

High energy alpha particles produced by neutron-induced nuclear reactions can damage severely reactor materials. Simulation of this process is described using theoretical calculation and ion irradiation experiments at different displacement doses and Helium doses.

Helium-induced weld cracking in austenitic and martensitic steels

International Nuclear Information System (INIS)

Lin, H.T.; Chin, B.A.

1991-01-01

Helium was uniformly implanted into type 316 stainless steel and Sandvik HT-9 (12Cr-1MoVW) to levels of 0.18 to 256 and 0.3 to 1 a.p.p.m., respectively, using the ''tritium trick'' technique. Autogenous bead-on-plate, full penetration, welds were then produced under fully constrained conditions using the gas tungsten arc welding (GTAW) process. The control and hydrogen-charged plates of both alloys were sound and free of any weld defects. For the 316 stainless steel, catastrophic intergranular fracture occurred in the heat-affected zone (HAZ) of welds with helium levels ≥ 2.5 a.p.p.m. In addition to the HAZ cracking, brittle fracture along the centreline of the fusion zone was also observed for the welds containing greater than 100 a.p.p.m. He. For HT-9, intergranular cracking occurred in the HAZ along prior-austenite grain boundaries of welds containing 1 a.p.p.m. He. Electron microscopy observations showed that the cracking in the HAZ originated from the growth and coalescence of grain-boundary helium bubbles and that the fusion-zone cracking resulted from the growth of helium bubbles at dendrite boundaries. The bubble growth kinetics in the HAZ is dominated by stress-induced diffusion of vacancies into bubbles. Results of this study indicate that the use of conventional GTAW techniques to repair irradiation-degraded materials containing even small amounts of helium may be difficult. (author)

Organic flash cycles for efficient power production

Science.gov (United States)

Ho, Tony; Mao, Samuel S.; Greif, Ralph

2016-03-15

This disclosure provides systems, methods, and apparatus related to an Organic Flash Cycle (OFC). In one aspect, a modified OFC system includes a pump, a heat exchanger, a flash evaporator, a high pressure turbine, a throttling valve, a mixer, a low pressure turbine, and a condenser. The heat exchanger is coupled to an outlet of the pump. The flash evaporator is coupled to an outlet of the heat exchanger. The high pressure turbine is coupled to a vapor outlet of the flash evaporator. The throttling valve is coupled to a liquid outlet of the flash evaporator. The mixer is coupled to an outlet of the throttling valve and to an outlet of the high pressure turbine. The low pressure turbine is coupled to an outlet of the mixer. The condenser is coupled to an outlet of the low pressure turbine and to an inlet of the pump.

High quality bio-oil from catalytic flash pyrolysis of lignocellulosic biomass over alumina-supported sodium carbonate

KAUST Repository

Imran, Ali; Bramer, Eddy A.; Seshan, Kulathuiyer; Brem, Gerrit

2014-01-01

Performance of a novel alumina-supported sodium carbonate catalyst was studied to produce a valuable bio-oil from catalytic flash pyrolysis of lignocellulosic biomass. Post treatment of biomass pyrolysis vapor was investigated in a catalyst fixed

Simulation study of radiation damage induced by energetic helium nuclei

International Nuclear Information System (INIS)

Hoang Dac Luc; Vo Tuong Hanh; Hoang Dac Dat

2003-01-01

High energy alpha particles produced by neutron-induced nuclear reactions can damage severely reactor materials. Simulation of this process is described using theoretical calculation and ion irradiation experiments at different displacement doses and Helium doses. (author)

Microstructure of wood charcoal prepared by flash heating

NARCIS (Netherlands)

Kurosaki, F; Ishimaru, K; Hata, T; Bronsveld, P; Kobayashi, E; Imamura, Y

2003-01-01

Carbonized wood prepared by flash heating at 800 degreesC for I h shows a different microstructure and surface chemical structure than char formed after slow heating at 4 degreesC/min to 800 degreesC for I h. Flash heating produces pores that are surrounded by aggregates of carbon structures 25 to

Monte Carlo analysis of helium production in the ITER shielding blanket module

International Nuclear Information System (INIS)

Sato, S.

1999-01-01

In order to examine the shielding performances of the inboard blanket module in the international thermonuclear experimental reactor (ITER), shielding calculations have been carried out using a three-dimensional Monte Carlo method. The impact of radiation streaming through the front access holes and gaps between adjacent blanket modules on the helium gas production in the branch pipe weld locations and back plate have been estimated. The three-dimensional model represents an 18 sector of the overall torus region and includes the vacuum vessel, inboard blanket and back plate, plasma region, and outboard reflecting medium. And it includes the 1 m high inboard mid-plane module and the 20 mm wide gaps between adjacent modules. From the calculated results for the reference design, it has been found that the helium production at the plug of the branch pipe is four to five times higher than the design goal of 1 appm for a neutron fluence of 0.9 MW a m -2 at the inboard mid-plane first wall. Also, it has been found that the helium production at the back plate behind the horizontal gap is about three times higher than the design goal. In the reference design, the stainless steel (SS):H 2 O composition in the blanket module is 80:20%. Shielding calculations also have been carried out for the SS:H 2 O composition of 70:30, 60:40, 50:50 and 40:60%. From the evaluated results for their design, it has been found that the dependence of helium production on the SS:H 2 170 mm will reduce helium production to satisfy the design goal and not have a significant impact on weight limitations imposed by remote maintenance handling limitations. Also based on the calculated results, about 200 mm thick shields such as a key structure in the vertical gap are suggested to be installed in the horizontal gap as well to reduce the helium production at the back plate and to satisfy the design goal. (orig.)

Kinetics of the flash-induced P515 response in relation to the H+-permeability of the membrane bound ATPase in spinach chloroplasts

Energy Technology Data Exchange (ETDEWEB)

Peters, R.L.; van Kooten, O.; Vredenberg, W.J.

1985-08-01

The effect of dicyclohexylcarbodiimide (DCCD) on the kinetics of the flash-induced P515 response and on the activity of the ATPase was investigated in isolated spinach chloroplasts. It was found that after the addition of 5 X 10(-8)mol DCCD the rate of ATP hydrolysis induced by a period of 60 sec illumination was decreased to less than 5% of its original value. At this concentration, hardly any effect, if at all, could be detected on the kinetics of the flash-induced P515 response, neither in dark-adapted nor in light-activated chloroplasts. It was concluded that the presence of concentrations of DCCD, sufficiently high to affect the ATPase activity, does not affect the kinetics of the flash-induced P515 response. Since DCCD decreases the H+ permeability of the membrane-bound ATPase, it was concluded that this permeability coefficient for protons is not an important factor in the regulation of the flash-induced membrane potential and, therefore, does not affect the kinetics of the flash-induced P515 response.

Effects of displacement damage and helium production rates on the nucleation and growth of helium bubbles - Positron annihilation spectroscopy aspects

Science.gov (United States)

Krsjak, Vladimir; Degmova, Jarmila; Sojak, Stanislav; Slugen, Vladimir

2018-02-01

Fe-12 wt% Cr model alloy samples were implanted by 250 keV He2+ ions to three different fluencies (3 × 1017, 9 × 1017 and 1.5 × 1018 cm-2) at T steel samples [1] irradiated in the frame of a two-years irradiation program of the Swiss Spallation Neutron Source. Bi-modal defect distribution represented by two defect components in positron lifetime spectrum reveals two distinct helium bubbles growth mechanisms. While at the lower helium production rate of the spallation environment, the bubbles grow primarily by migration and coalescence, at the high production rates of helium in the implanted samples, the results indicate this growth is driven by Ostwald ripening mechanism. A competitive growth process via emission of interstitial atoms (clusters) is discussed in terms of low-temperature He implantations.

Cosmological helium production simplified

International Nuclear Information System (INIS)

Bernstein, J.; Brown, L.S.; Feinberg, G.

1988-01-01

We present a simplified model of helium synthesis in the early universe. The purpose of the model is to explain clearly the physical ideas relevant to the cosmological helium synthesis, in a manner that does not overlay these ideas with complex computer calculations. The model closely follows the standard calculation, except that it neglects the small effect of Fermi-Dirac statistics for the leptons. We also neglect the temperature difference between photons and neutrinos during the period in which neutrons and protons interconvert. These approximations allow us to express the neutron-proton conversion rates in a closed form, which agrees to 10% accuracy or better with the exact rates. Using these analytic expressions for the rates, we reduce the calculation of the neutron-proton ratio as a function of temperature to a simple numerical integral. We also estimate the effect of neutron decay on the helium abundance. Our result for this quantity agrees well with precise computer calculations. We use our semi-analytic formulas to determine how the predicted helium abundance varies with such parameters as the neutron life-time, the baryon to photon ratio, the number of neutrino species, and a possible electron-neutrino chemical potential. 19 refs., 1 fig., 1 tab

Oxidation of Cu(II) aminopolycarboxylates by carbonate radical. A flash photolysis study

International Nuclear Information System (INIS)

Mandal, P.C.; Bardhan, D.K.

1999-01-01

Reactions of carbonate radical (CO 3 -. ) generated by photolysis or by radiolysis of a carbonate solution, with Cu(II) complexes of aminopolycarboxylic acids viz., Cu(II)ethylenediamine tetraacetate [Cu II EDTA] 2- and Cu(II)-iminodiacetate [Cu II IDA] were studied at pH 10.5 and ionic strength 0.2 mol x dm -3 . Time-resolved spectroscopy and kinetics for the transients were studied using flash photolysis and stable products arising from the ligand degradation of the complex were ascertained by steady-state radiolysis experiments. From the kinetic data it is observed that CO 3 -. radical reacts initially with Cu II -complex to form a transient intermediate having maximum absorption at 335 nm and 430 nm. From the subsequent reactions of this intermediate it was assigned to be Cu III .species. This Cu(III) species undergoes intermolecular electron transfer with the Cu II -complex to give a radical intermediate which again slowly reacts with Cu II -complex to give a long lived species containing Cu-C bond. This long lived species, however, slowly decomposed to give glyoxalic reaction between Cu III -complex and a suitable donor, the one electron reduction potential for [Cu III EDTA] 1- /[Cu II EDTA] 2- and [Cu III IDA] +1 /Cu II IDA was determined. (author)

Radiation damage in gallium-stabilized δ-plutonium with helium bubbles

Energy Technology Data Exchange (ETDEWEB)

Wu, FengChao [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wang, Pei [Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Liu, XiaoYi [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wu, HengAn, E-mail: wuha@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China)

2017-02-15

To understand the role of helium on self-irradiation effects in δ-plutonium, microstructure evolutions due to α-decay events near pre-existing helium bubbles in gallium-stabilized δ-plutonium are investigated using molecular dynamics simulations. Bubble promoting effect plays a dominating role in point defects production, resulting in increasing number of point defects. When lightweight helium atoms act as media, energy transfer discrepancy and altered spatial morphology of point defects induced by mass effect are revealed. The evolution of stacking faults surrounding the disordered core is studied and their binding effect on the propagation of point defects are presented. The cascade-induced bubble coalescence, resolution and re-nucleation driven by internal pressure are obtained in the investigation on helium behaviors. The intrinsic tendency in our simulated self-irradiation with helium bubbles is significant for understanding the underlying mechanism of aging in plutonium and its alloys.

Improvement of measurements, theoretical computations and evaluations of neutron induced helium production cross sections. Summary report on the third and final research co-ordination meeting

International Nuclear Information System (INIS)

Pashchenko, A.B.

1996-09-01

The present report contains the Summary of the Third and Final IAEA Research Co-ordination Meeting (RCM) on ''Improvement of Measurements, Theoretical Computations and Evaluations of Neutron Induced Helium Production Cross Sections'' which was hosted by the Tohoku University and held in Sendai, Japan, from 25 to 29 September 1995. This RCM was organized by the IAEA Nuclear Data Section (NDS), with the co-operation and assistance of local organizers from Tohoku University. Summarized are the proceedings and results of the meeting. The List of Participants and meeting Agenda are included. (author)

Biodiesel Production by Reactive Flash: A Numerical Simulation

Directory of Open Access Journals (Sweden)

Alejandro Regalado-Méndez

2016-01-01

Full Text Available Reactive flash (RF in biodiesel production has been studied in order to investigate steady-state multiplicities, singularities, and effect of biodiesel quality when the RF system approaches to bubble point. The RF was modeled by an index-2 system of differential algebraic equations, the vapor split (ϕ was computed by modified Rachford-Rice equation and modified Raoult’s law computed bubble point, and the continuation analysis was tracked on MATCONT. Results of this study show the existence of turning points, leading to a unique bubble point manifold, (xBiodiesel,T=(0.46,478.41 K, which is a globally stable flashing operation. Also, the results of the simulation in MATLAB® of the dynamic behavior of the RF show that conversion of triglycerides reaches 97% for a residence time of 5.8 minutes and a methanol to triglyceride molar flow ratio of 5 : 1.

Impact of helium implantation and ion-induced damage on reflectivity of molybdenum mirrors

Energy Technology Data Exchange (ETDEWEB)

Garcia-Carrasco, A., E-mail: alvarogc@kth.se [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden); Petersson, P.; Hallén, A. [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden); Grzonka, J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw (Poland); Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw (Poland); Gilbert, M.R. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Fortuna-Zalesna, E. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw (Poland); Rubel, M. [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden)

2016-09-01

Molybdenum mirrors were irradiated with Mo and He ions to simulate the effect of neutron irradiation on diagnostic first mirrors in next-generation fusion devices. Up to 30 dpa were produced under molybdenum irradiation leading to a slight decrease of reflectivity in the near infrared range. After 3 × 10{sup 17} cm{sup −2} of helium irradiation, reflectivity decreased by up to 20%. Combined irradiation by helium and molybdenum led to similar effects on reflectivity as irradiation with helium alone. Ion beam analysis showed that only 7% of the implanted helium was retained in the first 40 nm layer of the mirror. The structure of the near-surface layer after irradiation was studied with scanning transmission electron microscopy and the extent and size distribution of helium bubbles was documented. The consequences of ion-induced damage on the performance of diagnostic components are discussed.

Helium production measurements for neutron dosimetry and damage correlations

International Nuclear Information System (INIS)

Farrar, H. IV; Lippincott, E.P.

1978-01-01

Helium accumulation fluence monitors (HAFM's), consisting of miniature vanadium capsules containing small, accurately-known amounts of 10 B or 6 Li, are being used routinely for neutron dosimetry measurements in breeder reactor environments. Additionally, solid wires of Al, Fe and Cu have been irradiated by 14.8-MeV neutrons from the d-T reaction, and measurements of the helium production along these wires have given detailed neutron fluence profiles. Additional materials with relatively high (n,α) cross sections are being tested in a wide variety of neutron environments to select HAFM sets that will provide spectral information by unfolding techniques. The mass spectrometric helium measurement technique has been demonstrated to produce results with better than 2% (1 sigma) absolute accuracy. Intercomparisons with other laboratories have demonstrated good correlations with radiometric and fission chamber dosimetry results

Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

DEFF Research Database (Denmark)

Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

2013-01-01

We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

Effect of helium gas pressure on dc conduction mechanism and EMI shielding properties of nanocrystalline carbon thin films

Energy Technology Data Exchange (ETDEWEB)

Rawal, Ishpal, E-mail: rawalishpal@gmail.com [Department of Physics, Kirori Mal College, University of Delhi, Delhi 110007 (India); Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Singh, Avanish Pratap; Dhawan, S.K. [Polymeric and Soft Materials Group, Physics Engineering of Carbon, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

2015-05-05

This paper reports the effect of helium partial pressures ∼1.2 × 10{sup −5} (base pressure), 1.4 × 10{sup −4}, 8.6 × 10{sup −3} and 0.1 mbar on the variable range hopping conduction in nanocrystalline carbon thin films deposited by filtered cathodic jet carbon arc technique. High resolution transmission electron microscopy studies suggest the random distribution of nanocrystallites (∼3–7 nm) in the amorphous matrix. The DC conduction behavior of the deposited nanocrystalline films has been studied in the light of Mott's variable range hopping (VRH) model and found to obey three dimensional VRH conduction. The randomly distributed nanocrystallites in amorphous matrix may lead to change in the distribution of density of states near Fermi level and hence, the conduction behavior. The enhanced electrical conductivity of the deposited films due to the helium environment makes them suitable for electromagnetic interference shielding applications. The sample deposited at a helium partial pressure of 0.1 mbar has a value of shielding effectiveness ∼7.84 dB at 18 GHz frequency. - Highlights: • Nanocrystalline carbon thin films (NCTF) has been deposited by FCJCA technique. • Effect of helium gas pressure has been studied on the properties of NCTF. • Investigation of EMI shielding properties of NCTF has been carried out.

High quality bio-oil from catalytic flash pyrolysis of lignocellulosic biomass over alumina-supported sodium carbonate

NARCIS (Netherlands)

Ali Imran, A.; Bramer, Eduard A.; Seshan, Kulathuiyer; Brem, Gerrit

2014-01-01

Performance of a novel alumina-supported sodium carbonate catalyst was studied to produce a valuable bio-oil from catalytic flash pyrolysis of lignocellulosic biomass. Post treatment of biomass pyrolysis vapor was investigated in a catalyst fixed bed reactor at the downstream of the pyrolysis

Helium bubbles aggravated defects production in self-irradiated copper

Science.gov (United States)

Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

2017-12-01

Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

Calculation of displacement and helium production at the LAMPF irradiation facility

International Nuclear Information System (INIS)

Davidson, D.R.; Greenwood, L.R.; Sommer, W.F.; Wechsler, M.S.

1984-01-01

Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at LAMPF. The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 40 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

Laser Induced Fluorescence of Helium Ions in a Helicon Plasma

Science.gov (United States)

Compton, C. S.; Biloui, C.; Hardin, R. A.; Keesee, A. M.; Scime, E. E.; Boivin, R.

2003-10-01

The lack of a suitable Laser Induced Fluorescence (LIF) scheme for helium ions at visible wavelengths has prevented LIF from being employed in helium plasmas for measurements of ion temperature and bulk ion flow speeds. In this work, we will discuss our attempts to perform LIF of helium ions in a helicon source plasma using an infrared, tunable diode laser operating at 1012.36 nm. The infrared transition corresponds to excitation from the n = 4 level (4f ^2F) to the n = 5 (5g ^2G) level of singly ionized helium and therefore requires substantial electron temperatures (> 10 eV) to maintain an adequate ion population in the n = 4 state. Calculations using a steady state coronal model predict that the n = 4 state population will be 25% larger than the n = 5 population for our experimental conditions. The fluorescence decay from the n = 5 (5f ^2F) level of singly ionized helium level to the n = 3 (3d ^2D) level at 320.31 nm is monitored as the diode laser is swept through 10 GHz around the 1012.36 nm line. Note that the fluorescence emission requires a collisionally coupled transition between two different n = 5 quantum states. We will also present measurements of the emission intensities of both the 1012.36 nm and the 320.31 nm lines as a function of source neutral pressure, rf power, and plasma density. This work supported by the U.S. DoE EPSCoR Lab Partnership Program.

First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

International Nuclear Information System (INIS)

Morita, N.; Kumakura, M.; Yamazaki, T.

1993-11-01

We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, and show that the anomalous longevity of antiprotons previously observed in helium media results from the formation of high-n high-l atomic states of p-barHe + . The observed transition with vacuum wavelength 597.259 ± 0.002 nm and lower-state lifetime 15 ± 1 ns is tentatively assigned to (n,l) = (39,35) → (38,34). (author)

Production of bio-oil with flash pyrolysis; Biooeljyn tuotanto flash-pyrolyysillae ja sen poltto

Energy Technology Data Exchange (ETDEWEB)

Nyroenen, T [Vapo Oy, Jyvaeskylae (Finland)

1997-12-01

The target of the R and D work is to study the production of bio-oils using Flash-pyrolysis technology and utilisation of the bio-oil in oil-fuelled boilers. The PDU-unit was installed at VTT Energy in Otaniemi in April 1996. The first test were carried out in June. In the whole project Vapo Oy is responsible for: acquiring the 20 kg/h PDU-device for development; follow up of the engine tests; the investment of 5 MW demonstration plant; to carry on the boiler and engine tests with Finnish bio-oils. (orig.)

Isotopic alloying to tailor helium production rates in mixed spectrum reactors

International Nuclear Information System (INIS)

Mansur, L.K.; Rowcliffe, A.F.; Grossbeck, M.L.; Stoller, R.E.

1985-01-01

The purposes of this work are to increase the understanding of mechanisms by which helium affects microstructure and properties, to aid in the development of materials for fusion reactors, and to obtain data from fission reactors in regimes of direct interest for fusion reactor applications. Isotopic alloying is examined as a means of manipulating the ratio of helium transmutations to atom displacements in mixed spectrum reactors. The application explored is based on artificially altering the relative abundances of the stable isotopes of nickel to systematically vary the fraction of 58 Ni in nickel bearing alloys. The method of calculating helium production rates is described. Results of example calculations for proposed experiments in the High Flux Isotope Reactor are discussed

Effect of Carbon Concentration on the Sputtering of Carbon-Rich SiC Bombarded by Helium Ions

Directory of Open Access Journals (Sweden)

Xinghao Liang

2018-02-01

Full Text Available Silicon carbide (SiC is considered as an important material for nuclear engineering due to its excellent properties. Changing the carbon content in SiC can regulate and control its elastic and thermodynamic properties, but a simulation study of the effect of carbon content on the sputtering (caused by the helium ions of SiC is still lacking. In this work, we used the Monte-Carlo and molecular dynamics simulation methods to study the effects of carbon concentration, incidence energy, incident angle, and target temperature on the sputtering yield of SiC. The results show that the incident ions’ energy and angle have a significant effect on sputtering yield of SiC when the carbon concentration in SiC is around 62 at %, while the target temperature has a little effect on the sputtering yield of SiC. Our work might provide theoretical support for the experimental research and engineering application of carbon fiber-reinforced SiC that be used as the plasma-facing material in tokamak fusion reactors.

Helium-induced blistering and volume swelling in nickel

International Nuclear Information System (INIS)

Fenske, G.R.

1980-01-01

The results of an experimental investigation of helium-induced blistering are presented. The goal of the research was to examine the mechanisms involved in blistering by observing the microstructure of the implanted region using transmission electron microscopy (TEM). In particular, the volume swelling was measured as a function of the implant depth, and compared to experimental skin thicknesses in order to determine if the skin separated at the maximum volume swelling, or at the end of the swelling profile

Calculation of displacement and helium production at the LAMPF irradiation facility

International Nuclear Information System (INIS)

Wechsler, M.S.; Davidson, D.R.; Sommer, W.F.; Greenwood, L.R.

1985-01-01

Differential and total displacement and helium-production rates are calculated for copper irradiated by spallation neutrons and 760-MeV protons at LAMPF. The calculations are performed using the SPECTOR and VNMTC computer codes, the latter being specially designed for spallation radiation-damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in the experimental breeder reactor (EBR-II) at the Argonne National Laboratory-West in Idaho, and in the rotating target neutron source (RTNS-II) at Lawrence Livermore Laboratory. The neutron energy spectra for LAMPF, EBR-II, and RTNS-II and the displacement and helium-production cross sections are shown

Single electron detachment of carbon group and oxygen group elements incident on helium

International Nuclear Information System (INIS)

Huang Yongyi; Li Guangwu; Gao Yinghui; Yang Enbo; Gao Mei; Lu Fuquan; Zhang Xuemei

2006-01-01

The absolute single electron detachment (SED) cross sections of carbon group elements C - , Si - , Ge - in the energy range of 0.05-0.29 a.u. (5 keV-30 keV) and oxygen group elements O - and S - 0.08-0.27 a.u. (5 keV-30 keV), incident on helium are measured with growth rate method. In our energy region, the SED cross sections of C - , Si - , S - and Ge - increase with the projectiles velocity, at the same time, O - cross sections reach a conspicuous maximum at 0.18 a.u. Some abnormal behavior occurs in measurement of SED cross sections for the oxygen group collision with helium. Our results have been compared with a previous work

Terrestrial gamma ray flash production by active lightning leader channels

OpenAIRE

İnan, Umran Savaş; Carlson, B. E.; Lehtinen, N. G.

2017-01-01

The production of terrestrial gamma ray flashes (TGFs) requires a seed energetic electron source and a strong electric field. Lightning leaders naturally provide seed electrons by cold runaway and strong electric fields by charge accumulation on the channel. We model possible TGF production in such fields by simulating the charges and currents on the channel. The resulting electric fields then drive simulations of runaway relativistic electron avalanche and photon emission. Photon spectra and...

A New Formation Mechanism for the Hottest Horizontal-Branch Stars

Science.gov (United States)

Sweigart, Allen V.; Oegerle, William R. (Technical Monitor)

2002-01-01

Hot subluminous stars lying up to 0.7 mag below the extreme horizontal branch (EHB) are found in the ultraviolet color-magnitude diagrams (CMDs) of both omega Cen and NGC 2808. In order to investigate the origin of these subluminous stars, we have constructed a detailed set of evolutionary sequences that follow the evolution of low-mass stars continuously from the zero-age main sequence through the helium-core flash to the HB for a wide range in the mass loss along the red-giant branch (RGB). Stars with the largest mass loss evolve off the RGB to high effective temperatures before igniting helium in their cores. Our results indicate that the subluminous EHB stars, as well as the high temperature gap along the EHB of NGC 2808, can be explained if these stars undergo a late helium-core flash while descending the white-dwarf cooling curve. Under these conditions the convection zone produced by the main helium flash will penetrate into the stellar envelope, thereby mixing most, if not all, of the envelope hydrogen into the hot helium-burning interior, where it is rapidly consumed. This phenomenon is analogous to the 'born-again' scenario for producing hydrogen-deficient stars following a very late helium-shell flash. This 'flash mixing' of the envelope during a late helium-core flash greatly enhances the envelope helium and carbon abundances and, as a result, leads to a discontinuous increase in the HB effective temperature. We argue that the hot HB gap observed in NGC 2808 is associated with this theoretically predicted dichotomy in the RB properties. Using new helium- and carbon-rich stellar atmospheres, we show that the changes in the envelope abundances due to flash mixing will suppress the ultraviolet flux in the spectra of hot EHB stars. We suggest that such changes in the emergent spectral energy distribution are primarily responsible for explaining the hot subluminous EHB stars in omega Cen and NGC 2808. Moreover, we demonstrate that models without flash mixing

Thermal characterization of a flashing jet by planar laser-induced fluorescence

Science.gov (United States)

Vetrano, M. R.; Simonini, A.; Steelant, J.; Rambaud, P.

2013-07-01

Flash atomization can be observed when a pressurized fluid is released in an environment at lower pressure. This phenomenon plays an important role in the security management of chemical industries where liquefied gases can be accidentally released at atmosphere. In other applications, for example in propulsion systems, it can have some potential benefits as it is known to produce a fine spray with enhanced atomization. The experimental characterization of these kinds of atomization should be performed by means of non-intrusive measurement techniques since they are very sensitive to external perturbation. In this work, the planar laser-induced fluorescence technique is used to measure the liquid phase temperature of an ethanol superheated flashing jet. The feasibility of the technique is proved, measurements are taken for different superheat conditions, and an analysis of the measurement uncertainties is presented.

The thermodynamic properties of normal liquid helium 3

Science.gov (United States)

Modarres, M.; Moshfegh, H. R.

2009-09-01

The thermodynamic properties of normal liquid helium 3 are calculated by using the lowest order constrained variational (LOCV) method. The Landau Fermi liquid model and Fermi-Dirac distribution function are considered as our statistical model for the uncorrelated quantum fluid picture and the Lennard-Jones and Aziz potentials are used in our truncated cluster expansion (LOCV) to calculate the correlated energy. The single particle energy is treated variationally through an effective mass. The free energy, pressure, entropy, chemical potential and liquid phase diagram as well as the helium 3 specific heat are evaluated, discussed and compared with the corresponding available experimental data. It is found that the critical temperature for the existence of the pure gas phase is about 4.90 K (4.45 K), which is higher than the experimental prediction of 3.3 K, and the helium 3 flashing temperature is around 0.61 K (0.50 K) for the Lennard-Jones (Aziz) potential.

Helium-induced weld degradation of HT-9 steel

International Nuclear Information System (INIS)

Wang, Chin-An; Chin, B.A.; Lin, Hua T.; Grossbeck, M.L.

1992-01-01

Helium-bearing Sandvik HT-9 ferritic steel was tested for weldability to simulate the welding of structural components of a fusion reactor after irradiation. Helium was introduced into HT-9 steel to 0.3 and 1 atomic parts per million (appm) by tritium doping and decay. Autogenous single pass full penetration welds were produced using the gas tungsten arc (GTA) welding process under laterally constrained conditions. Macroscopic examination showed no sign of any weld defect in HT-9 steel containing 0.3 appm helium. However, intergranular micro cracks were observed in the HAZ of HT-9 steel containing 1 appm helium. The microcracking was attributed to helium bubble growth at grain boundaries under the influence of high stresses and temperatures that were present during welding. Mechanical test results showed that both yield strength (YS) and ultimate tensile strength (UTS) decreased with increasing temperature, while the total elongation increased with increasing temperature for all control and helium-bearing HT-9 steels

Prolonged Helium Postconditioning Protocols during Early Reperfusion Do Not Induce Cardioprotection in the Rat Heart In Vivo: Role of Inflammatory Cytokines

Directory of Open Access Journals (Sweden)

Gezina Tanya Mei Ling Oei

2015-01-01

Full Text Available Postconditioning of myocardial tissue employs short cycles of ischemia or pharmacologic agents during early reperfusion. Effects of helium postconditioning protocols on infarct size and the ischemia/reperfusion-induced immune response were investigated by measurement of protein and mRNA levels of proinflammatory cytokines. Rats were anesthetized with S-ketamine (150 mg/kg and diazepam (1.5 mg/kg. Regional myocardial ischemia/reperfusion was induced; additional groups inhaled 15, 30, or 60 min of 70% helium during reperfusion. Fifteen minutes of helium reduced infarct size from 43% in control to 21%, whereas 30 and 60 minutes of helium inhalation led to an infarct size of 47% and 39%, respectively. Increased protein levels of cytokine-induced neutrophil chemoattractant (CINC-3 and interleukin-1 beta (IL-1β were found after 30 or 60 min of helium inhalation, in comparison to control. 30 min of helium increased mRNA levels of CINC-3, IL-1β, interleukin 6 (IL-6, and tumor necrosis factor alpha (TNF-α in myocardial tissue not directly subjected to ischemia/reperfusion. These results suggest that the effectiveness of the helium postconditioning protocol is very sensitive to duration of noble gas application. Additionally, helium was associated with higher levels of inflammatory cytokines; however, it is not clear whether this is causative of nature or part of an epiphenomenon.

Laser-induced carbon plasma emission spectroscopic measurements on solid targets and in gas-phase optical breakdown

International Nuclear Information System (INIS)

Nemes, Laszlo; Keszler, Anna M.; Hornkohl, James O.; Parigger, Christian

2005-01-01

We report measurements of time- and spatially averaged spontaneous-emission spectra following laser-induced breakdown on a solid graphite/ambient gas interface and on solid graphite in vacuum, and also emission spectra from gas-phase optical breakdown in allene C3H4 and helium, and in CO2 and helium mixtures. These emission spectra were dominated by CII (singly ionized carbon), CIII (doubly ionized carbon), hydrogen Balmer beta (H b eta), and Swan C2 band features. Using the local thermodynamic equilibrium and thin plasma assumptions, we derived electron number density and electron temperature estimates. The former was in the 1016 cm -3 range, while the latter was found to be near 20000 K. In addition, the vibration-rotation temperature of the Swan bands of the C2 radical was determined to be between 4500 and 7000 K, using an exact theoretical model for simulating diatomic emission spectra. This temperature range is probably caused by the spatial inhomogeneity of the laser-induced plasma plume. Differences are pointed out in the role of ambient CO2 in a solid graphite target and in gas-phase breakdown plasma

Exotic helium molecules; Molecules exotiques d'helium

Energy Technology Data Exchange (ETDEWEB)

Portier, M

2007-12-15

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

Science.gov (United States)

Hendricks, R. C.; Baron, A. K.; Peller, I. C.

1975-01-01

A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

Dynamics of C2 formation in laser-produced carbon plasma in helium environment

International Nuclear Information System (INIS)

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.; Polek, M.

2011-01-01

We investigated the role of helium ambient gas on the dynamics of C 2 species formation in laser-produced carbon plasma. The plasma was produced by focusing 1064 nm pulses from an Nd:YAG laser onto a carbon target. The emission from the C 2 species was studied using optical emission spectroscopy, and spectrally resolved and integrated fast imaging. Our results indicate that the formation of C 2 in the plasma plume is strongly affected by the pressure of the He gas. In vacuum, the C 2 emission zone was located near the target and C 2 intensity oscillations were observed both in axial and radial directions with increasing the He pressure. The oscillations in C 2 intensity at higher pressures in the expanding plume could be caused by various formation zones of carbon dimers.

Evolution of helium stars: a self-consistent determination of the boundary of a helium burning convective core

International Nuclear Information System (INIS)

Savonije, G.J.; Takens, R.J.

1976-01-01

A generalization of the Henyey-scheme is given that introduces the mass of the convective core and the density at the outer edge of the convective core boundary as unknowns which have to be solved simultaneously with the other unknowns. As a result, this boundary is determined in a physically self-consistent way for expanding as well as contracting cores, i.e. during the Henyey iterative cycle; its position becomes consistent with the overall physical structure of the star, including the run of the chemical abundances throughout the star. Using this scheme, the evolution of helium stars was followed up to carbon ignition for a number of stellar masses. As compared with some earlier investigations, the calculations show a rather large increase in mass of the convective cores during core helium burning. Evolutionary calculations for a 2M(sun) helium star show that the critical mass for which a helium star ignites carbon non-degenerately lies near 2M(sun). (orig.) [de

Foundation Flash Cartoon Animation

CERN Document Server

Jones, Tim; Rosson, Allan S

2008-01-01

One of Flash s most common uses is still animation for cartoons, games, advertising etc, and this book takes a fresh look at the topic, breaking it down pre-production, production, and post production, and looking at each section in detail, and covering topics such as storyboarding, character libraries and camera mechanics like no Flash book has before. The book is written by members of the Emmy award winning ANIMAX team, who have created work for clients such as Disney, AOL, Fox, WWE, ESPN, and Sesame workshop. This book is an opportunity for them to share their secrets, and is written to sui

The Modular Helium Reactor for Hydrogen Production

International Nuclear Information System (INIS)

E. Harvego; M. Richards; A. Shenoy; K. Schultz; L. Brown; M. Fukuie

2006-01-01

For electricity and hydrogen production, an advanced reactor technology receiving considerable international interest is a modular, passively-safe version of the high-temperature, gas-cooled reactor (HTGR), known in the U.S. as the Modular Helium Reactor (MHR), which operates at a power level of 600 MW(t). For hydrogen production, the concept is referred to as the H2-MHR. Two concepts that make direct use of the MHR high-temperature process heat are being investigated in order to improve the efficiency and economics of hydrogen production. The first concept involves coupling the MHR to the Sulfur-Iodine (SI) thermochemical water splitting process and is referred to as the SI-Based H2-MHR. The second concept involves coupling the MHR to high-temperature electrolysis (HTE) and is referred to as the HTE-Based H2-MHR

Helium release rates and ODH calculations from RHIC magnet cooling line failure

Energy Technology Data Exchange (ETDEWEB)

Liaw, C.J.; Than, Y.; Tuozzolo, J.

2011-03-28

A catastrophic failure of the magnet cooling lines, similar to the LHC superconducting bus failure incident, could discharge cold helium into the RHIC tunnel and cause an Oxygen Deficiency Hazard (ODH) problem. A SINDA/FLUINT{reg_sign} model, which simulated the 4.5K/4 atm helium flowing through the magnet cooling system distribution lines, then through a line break into the insulating vacuum volumes and discharging via the reliefs into the RHIC tunnel, had been developed. Arc flash energy deposition and heat load from the ambient temperature cryostat surfaces are included in the simulations. Three typical areas: the sextant arc, the Triplet/DX/D0 magnets, and the injection area, had been analyzed. Results, including helium discharge rates, helium inventory loss, and the resulting oxygen concentration in the RHIC tunnel area, are reported. Good agreement had been achieved when comparing the simulation results, a RHIC sector depressurization test measurement, and some simple analytical calculations.

Exotic helium molecules; Molecules exotiques d'helium

Energy Technology Data Exchange (ETDEWEB)

Portier, M

2007-12-15

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

Mixing core material into the envelopes of red grants

International Nuclear Information System (INIS)

Deupree, R.G.

1986-01-01

A discussion is presented of calculations of four core helium flashes in red giant stars. The starting point for these calculations is a point source explosion on the polar axis of a two-dimensional finite difference grid. The amount of residue of the core helium flash mixed into and above the hydrogen shell is calculated at four temperatures for the elements carbon, oxygen, neon, magnesium, silicon, and sulfur. 7 refs., 1 tab

Effects of initial microstructure and helium production on radiation hardening in F82H Steels

Energy Technology Data Exchange (ETDEWEB)

Okubo, N.; Wakai, E.; Takada, F.; Jitsukawa, S. [Japan Atomic Energy Agency, Naga-gun, Ibaraki-ken (Japan); Katoh, Y. [Oak Ridge Noational Laboratory, TN (United States)

2007-07-01

Full text of publication follows: Fission neutron irradiation to steels doped with isotope boron-10 is frequently conducted to study effects of the helium production on mechanical properties. The intrinsic mechanical properties of F82H steels could have been changed due to the boron doping. Recently, we reported that co-doping with boron and nitrogen to F82H (F82H+B+N) improved the mechanical properties of F82H doped only with boron. The mechanical properties of F82H+B+N are successfully comparable with the non-doped F82H before irradiation. In order to evaluate the effects of initial microstructure and helium production on radiation hardening, F82H and F82H+B+N were irradiate d Specimens used in this study were standard F82H martensitic steels, F82H steels doped with 60 mass ppm {sup 10}B and 200 ppm N (F82H+10B+N) and F82H steels doped with 60 mass ppm {sup 11}B and 200 ppm N (F82H+11B+N). Initial microstructures were changed by tempering conditions, and the tempering temperatures were at 700, 750 and 780 deg. C. Irradiation was performed at nominally 250 deg. C to 2 dpa in JMTR. Tensile properties were measured for the specimens before and after irradiation. Change of yield stress due to the irradiation in the F82H+11B+N steels depended strongly on the initial microstructure and hardness before irradiation. The radiation hardening due to helium production in the F82H+10B+N steels was less than 60 MPa in these experiments. Size of dimple in the fracture surface of specimen with helium production was larger than that with non-helium production. (authors)

The consequences of helium production on microstructural development in isotopically tailored ferritic alloys

International Nuclear Information System (INIS)

Gelles, D.S.

1996-01-01

A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of 60 Ni which produces no helium, 59 Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel ( Nat Ni) which provides an intermediate level of helium due to delayed development of 59 Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to ∼7 dpa at 300 and 400 degrees C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400 degrees C than at 300 degrees C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from 59 Ni and Nat Ni. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400 degrees C. At 300 degrees C, it appeared that high densities of bubbles formed whereas at 400 degrees C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces

The consequences of helium production on microstructural development in isotopically tailored ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Gelles, D.S. [Pacific Northwest Lab., Richland, WA (United States)

1996-10-01

A series of alloys have been made adding various isotopes of nickel in order to vary the production of helium during irradiation by a two step nuclear reaction in a mixed spectrum reactor. The alloys use a base composition of Fe-12Cr with an addition of 1.5% nickel, either in the form of {sup 60}Ni which produces no helium, {sup 59}Ni which produces helium at a rate of about 10 appm He/dpa, or natural nickel ({sup Nat}Ni) which provides an intermediate level of helium due to delayed development of {sup 59}Ni. Specimens were irradiated in the HFIR at Oak Ridge, TN to {approx}7 dpa at 300 and 400{degrees}C. Microstructural examinations indicated that nickel additions promote precipitation in all alloys, but the effect appears to be much stronger at 400{degrees}C than at 300{degrees}C. There is sufficient dose by 7 dpa (and with 2 appm He) to initiate void swelling in ferritic/martensitic alloys. Little difference was found between response from {sup 59}Ni and {sup Nat}Ni. Also, helium bubble development for high helium generation conditions appeared to be very different at 300 and 400{degrees}C. At 300{degrees}C, it appeared that high densities of bubbles formed whereas at 400{degrees}C, bubbles could not be identified, possibly because of the complexity of the microstructure, but more likely because helium accumulated at precipitate interfaces.

Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

Directory of Open Access Journals (Sweden)

S. S. Bulanov

2015-06-01

Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

HEATHER - HElium Ion Accelerator for RadioTHERapy

Energy Technology Data Exchange (ETDEWEB)

Taylor, Jordan [Huddersfield U.; Edgecock, Thomas [Huddersfield U.; Green, Stuart [Birmingham U.; Johnstone, Carol [Fermilab

2017-05-01

A non-scaling fixed field alternating gradient (nsFFAG) accelerator is being designed for helium ion therapy. This facility will consist of 2 superconducting rings, treating with helium ions (He²⁺ ) and image with hydrogen ions (H + 2 ). Currently only carbon ions are used to treat cancer, yet there is an increasing interest in the use of lighter ions for therapy. Lighter ions have reduced dose tail beyond the tumour compared to carbon, caused by low Z secondary particles produced via inelastic nuclear reactions. An FFAG approach for helium therapy has never been previously considered. Having demonstrated isochronous acceleration from 0.5 MeV to 900 MeV, we now demonstrate the survival of a realistic beam across both stages.

Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions.

Science.gov (United States)

Zhang, Rui; Taddei, Phillip J; Fitzek, Markus M; Newhauser, Wayne D

2010-05-07

Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient's body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several simple analytical formulas previously developed for proton beams for their ability to calculate WET values for materials exposed to beams of protons, helium, carbon and iron ions. Experimentally measured heavy charged particle beam ranges and WET values from an iterative numerical method were compared with the WET values calculated by the analytical formulas. In most cases, the deviations were within 1 mm. We conclude that the analytical formulas originally developed for proton beams can also be used to calculate WET values for helium, carbon and iron ion beams with good accuracy.

Biomass flash pyrolysis for energy and chemical inputs production; Pirolise ultra-rapida de biomassas para obtencao de insumos quimicos e energeticos

Energy Technology Data Exchange (ETDEWEB)

Luengo, Carlos A; Cencig, Mario O [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica

1988-12-31

In this work, flash pyrolysis, a modern processing technique applied to biomass and municipal wastes, is critically reviewed. Similarities and differences with the process of carbonization are indicated in relation to main processing parameters. At the University of Campinas, Brazil (UNICAMP), flash pyrolysis development and applications to high ash coals usually founds in the southern Brazil. Presently, research is being extended to include types of biomass relevant to local conditions. (author) 28 refs., 3 figs., 1 tab.

High flash point electrolyte for use in lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Isken, P.; Dippel, C.; Schmitz, R.; Schmitz, R.W.; Kunze, M.; Passerini, S.; Winter, M. [Institute of Physical Chemistry, Westfaelische Wilhelms-University Muenster, Corrensstrasse 28/30, 48149 Muenster (Germany); Lex-Balducci, A., E-mail: a.lex-balducci@uni-muenster.de [Institute of Physical Chemistry, Westfaelische Wilhelms-University Muenster, Corrensstrasse 28/30, 48149 Muenster (Germany)

2011-09-01

Highlights: > Substitution of linear carbonates in conventional electrolytes with adiponitrile allows the realization of high flash point electrolytes. > EC:ADN based electrolytes display a higher anodic stability than a conventional electrolyte based on EC:DEC. > Graphite and NCM electrodes used in combination with the EC:ADN based electrolyte display a performance comparable with that of conventional electrolytes. - Abstract: The high flash point solvent adiponitrile (ADN) was investigated as co-solvent with ethylene carbonate (EC) for use as lithium-ion battery electrolyte. The flash point of this solvent mixture was more than 110 deg. C higher than that of conventional electrolyte solutions involving volatile linear carbonate components, such as diethyl carbonate (DEC) or dimethyl carbonate (DMC). The electrolyte based on EC:ADN (1:1 wt) with lithium tetrafluoroborate (LiBF{sub 4}) displayed a conductivity of 2.6 mS cm{sup -1} and no aluminum corrosion. In addition, it showed higher anodic stability on a Pt electrode than the standard electrolyte 1 M lithium hexafluorophosphate (LiPF{sub 6}) in EC:DEC (3:7 wt). Graphite/Li half cells using this electrolyte showed excellent rate capability up to 5C and good cycling stability (more than 98% capacity retention after 50 cycles at 1C). Additionally, the electrolyte was investigated in NCM/Li half cells. The cells were able to reach a capacity of 104 mAh g{sup -1} at 5C and capacity retention of more than 97% after 50 cycles. These results show that an electrolyte with a considerably increased flash point with respect to common electrolyte systems comprising linear carbonates, could be realized without any negative effects on the electrochemical performance in Li-half cells.

Comparison of piascledine (avocado and soybean oil) and hormone replacement therapy in menopausal-induced hot flashing.

Science.gov (United States)

Panahi, Yunes; Beiraghdar, Fatemeh; Kashani, Nafise; Baharie Javan, Nika; Dadjo, Yahya

2011-01-01

Different symptoms in Climacteric period, includes hot flash. Hormone replacement therapy (HRT) is common therapy for relief of menopausal symptoms but has possible contraindications and side effects. Recently Piascledine (combination of Avocado oil with Soybean oil) showed effects in reducing hot flash severity. Present study designed to compare the effects of HRT with Piascledine in treatment of hot flash. The cases of this study were sixty-six women at the age range of 40 to 70 years and complaints of menopause-induced hot flashing, whose last menstruation dated at least 6 months prior to the beginning of the study. The patients in this open label clinical trial, randomized to receive Piascledine capsule 1 mg or HRT (0.625 mg oral daily Conjugated Estrogen tablets, plus 2.5 mg continuous oral daily Medroxyprogesterone Acetate tablets) for 2 month. Hot flash property and severity was assessed via a daily check list and Visual analog scale. Climacteric symptom was measured before and after intervention using Greene Climacteric Scale (GCS) and Blatt-kupperman Menopausal Index (BKMI). Thirty-three eligible patients were allocated in each group. From the Piascledine group, one patient and from the HRT group, 16 patients weren›t willing to attend the study; therefore, 32 and 17 woman received treatment in Piascledine and HRT groups. 4 patients were withdrawn for vaginal bleeding and one for breast tenderness from HTR group. Hot flash severity in both groups decreased during the time similarly. With regard to GCS (p = 0.571) and BMKI (p = 0.891), the outcome was similar among the two groups. Due to low HRT compliance and its possible risks in long period of time and considering the same activity of soybean supplement and HRT in relieving the hot flash as menopausal symptoms in women, it seems that soybean supplements can be an alternative therapy to hormone.

Simplified production of multimedia based radiological learning objects using the flash format

International Nuclear Information System (INIS)

Jedrusik, P.; Preisack, M.; Dammann, F.

2005-01-01

Purpose: evaluation of the applicability of the flash format for the production of radiological learning objects used in an e-learning environment. Material and methods: five exemplary learning objects with different didactic purposes referring to radiological diagnostics are presented. They have been intended for the use within the multimedia, internet-based e-learning environment LaMedica. Interactive learning objects were composed using the Flash 5.0 software (Macromedia, San Francisco, USA) on the basis of digital CT and MR images, digitized conventional radiographs and different graphical elements prepared as TIFF files or in a vector graphics format. Results: after a short phase of initial skill adaptation training, a radiologist author was soon able to create independently all learning objects. The import of different types of images and graphical elements was carried out without complications. Despite manifold design options, handling of the program is easy due to clear arrangement and structure, thus enabling the creation of simple as well as complex learning objects that provided a high degree of attractiveness and interaction. Data volume and bandwidth demand for online use was significantly reduced by the flash format compression without a substantial loss of visual quality. (orig.)

Convoluted dislocation loops induced by helium irradiation in reduced-activation martensitic steel and their impact on mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Luo, Fengfeng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yao, Z. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada K7L 3N6 (Canada); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Suo, Jinping [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wen, Yongming [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

2014-06-01

Helium irradiation induced dislocation loops in reduced-activation martensitic steels were investigated using transmission electron microscopy. The specimens were irradiated with 100 keV helium ions to 0.8 dpa at 350 °C. Unexpectedly, very large dislocation loops were found, significantly larger than that induced by other types of irradiations under the same dose. Moreover, the large loops were convoluted and formed interesting flower-like shape. The large loops were determined as interstitial type. Loops with the Burgers vectors of b=〈100〉 were only observed. Furthermore, irradiation induced hardening caused by these large loops was observed using the nano-indentation technique.

Reactive Oxygen Species and Mitochondrial KATP Channels Mediate Helium-Induced Preconditioning Against Myocardial Infarction In Vivo

Science.gov (United States)

Pagel, Paul S.; Krolikowski, John G.; Pratt, Phillip F.; Shim, Yon Hee; Amour, Julien; Warltier, David C.; Weihrauch, Dorothee

2008-01-01

Objectives Helium produces preconditioning by activating prosurvival kinases, but the roles of reactive oxygen species (ROS) or mitochondrial KATP channels in this process are unknown. We tested the hypothesis that ROS and mitochondrial KATP channels mediate helium-induced preconditioning in vivo. Design Randomized, prospective study. Setting University research laboratory. Participants Male New Zealand white rabbits. Interventions Rabbits (n=64) were instrumented for measurement of systemic hemodynamics and subjected to a 30 min left anterior descending coronary artery (LAD) occlusion and 3 h reperfusion. In separate experimental groups, rabbits (n=7 or 8 per group) were randomly assigned to receive 0.9% saline (control) or three cycles of 70% helium-30% oxygen administered for 5 min interspersed with 5 min of an air-oxygen mixture before LAD occlusion with or without the ROS scavengers N-acetylcysteine (NAC; 150 mg/kg) or N-2-mercaptoproprionyl glycine (2-MPG; 75 mg/kg), or the mitochondrial KATP antagonist 5-hydroxydecanoate (5-HD; 5 mg/kg). Statistical analysis of data was performed with analysis of variance for repeated measures followed by Bonferroni's modification of Student's t test. Measurements and Main Results Myocardial infarct size was determined using triphenyltetrazolium chloride staining and presented as a percentage of the left ventricular area at risk. Helium significantly (P<0.05) reduced infarct size (23±4% of the area at risk; mean±SD) compared with control (46±3%). NAC, 2-MPG, and 5-HD did not affect irreversible ischemic injury when administered alone (49±5, 45±6, and 45±3%), but these drugs blocked reductions in infarct size produced by helium (45±4, 45±2, and 44±3%). Conclusions The results suggest that ROS and mitochondrial KATP channels mediate helium-induced preconditioning in vivo. PMID:18662630

Diamond-like-carbon nanoparticle production and agglomeration following UV multi-photon excitation of static naphthalene/helium gas mixtures

Energy Technology Data Exchange (ETDEWEB)

Walsh, A. J.; Ruth, A. A., E-mail: a.ruth@ucc.ie [Physics Department and Environmental Research Institute, University College Cork, Cork (Ireland); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333-CA Leiden (Netherlands)

2016-07-14

We report the formation of nanoparticles with significant diamond character after UV multi-photon laser excitation of gaseous naphthalene, buffered in static helium gas, at room temperature. The nanoparticles are identified in situ by their absorption and scattering spectra between 400 and 850 nm, which are modeled using Mie theory. Comparisons of the particles’ spectroscopic and optical properties with those of carbonaceous materials indicate a sp{sup 3}/sp{sup 2} hybridization ratio of 8:1 of the particles formed. The particle extinction in the closed static (unstirred) gas-phase system exhibits a complex and quasi-oscillatory time dependence for the duration of up to several hours with periods ranging from seconds to many minutes. The extinction dynamics of the system is based on a combination of transport features and particle interaction, predominantly agglomeration. The relatively long period of agglomeration allows for a unique analysis of the agglomeration process of diamond-like carbon nanoparticles in situ.

Plasmid DNA damage induced by helium atmospheric pressure plasma jet

Science.gov (United States)

Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

2014-03-01

A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

An evaluation of reactor cooling and coupled hydrogen production processes using the modular helium reactor

International Nuclear Information System (INIS)

Harvego, E.A.; Reza, S.M.M.; Richards, M.; Shenoy, A.

2006-01-01

The high-temperature characteristics of the modular helium reactor (MHR) make it a strong candidate for producing hydrogen using either thermochemical or high-temperature electrolysis (HTE) processes. Using heat from the MHR to drive a sulfur-iodine (SI) thermochemical hydrogen production process has been the subject of a U.S. Department of Energy sponsored Nuclear Engineering Research Initiative (NERI) project led by General Atomics, with participation from the Idaho National Laboratory (INL) and Texas A and M University. While the focus of much of the initial work was on the SI thermochemical production of hydrogen, recent activities included development of a preconceptual design for an integral HTE hydrogen production plant driven by the process heat and electricity produced by a 600 MW MHR. This paper describes ATHENA analyses performed to evaluate alternative primary system cooling configurations for the MHR to minimize peak reactor vessel and core temperatures while achieving core helium outlet temperatures in the range of 900-1000 deg. C that are needed for the efficient production of hydrogen using either the SI or HTE process. The cooling schemes investigated are intended to ensure peak fuel temperatures do not exceed specified limits under normal or transient upset conditions, and that reactor vessel temperatures do not exceed American Society of Mechanical Engineers (ASME) code limits for steady-state or transient conditions using standard light water reactor vessel materials. Preconceptual designs for SI and HTE hydrogen production plants driven by one or more 600 MW MHRs at helium outlet temperatures in the range of 900-1000 deg. C are described and compared. An initial SAPHIRE model to evaluate the reliability, maintainability, and availability of the SI hydrogen production plant is also described. Finally, a preliminary flowsheet for a conceptual design of an HTE hydrogen production plant coupled to a 600 MW modular helium reactor is presented and

Low helium flux from the mantle inferred from simulations of oceanic helium isotope data

Science.gov (United States)

Bianchi, Daniele; Sarmiento, Jorge L.; Gnanadesikan, Anand; Key, Robert M.; Schlosser, Peter; Newton, Robert

2010-09-01

The high 3He/ 4He isotopic ratio of oceanic helium relative to the atmosphere has long been recognized as the signature of mantle 3He outgassing from the Earth's interior. The outgassing flux of helium is frequently used to normalize estimates of chemical fluxes of elements from the solid Earth, and provides a strong constraint to models of mantle degassing. Here we use a suite of ocean general circulation models and helium isotope data obtained by the World Ocean Circulation Experiment to constrain the flux of helium from the mantle to the oceans. Our results suggest that the currently accepted flux is overestimated by a factor of 2. We show that a flux of 527 ± 102 mol year - 1 is required for ocean general circulation models that produce distributions of ocean ventilation tracers such as radiocarbon and chlorofluorocarbons that match observations. This new estimate calls for a reevaluation of the degassing fluxes of elements that are currently tied to the helium fluxes, including noble gases and carbon dioxide.

Exotic helium molecules

International Nuclear Information System (INIS)

Portier, M.

2007-12-01

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4 He 2 (2 3 S 1 -2 3 P 0 ) molecule, or a 4 He 2 (2 3 S 1 -2 3 S 1 ) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4 He 2 (2 3 S 1 -2 3 S 1 ) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

Mathematical modeling of unicellular microalgae and cyanobacteria metabolism for biofuel production.

Science.gov (United States)

Baroukh, Caroline; Muñoz-Tamayo, Rafael; Bernard, Olivier; Steyer, Jean-Philippe

2015-06-01

The conversion of microalgae lipids and cyanobacteria carbohydrates into biofuels appears to be a promising source of renewable energy. This requires a thorough understanding of their carbon metabolism, supported by mathematical models, in order to optimize biofuel production. However, unlike heterotrophic microorganisms that utilize the same substrate as sources of energy and carbon, photoautotrophic microorganisms require light for energy and CO2 as carbon source. Furthermore, they are submitted to permanent fluctuating light environments due to outdoor cultivation or mixing inducing a flashing effect. Although, modeling these nonstandard organisms is a major challenge for which classical tools are often inadequate, this step remains a prerequisite towards efficient optimization of outdoor biofuel production at an industrial scale. Copyright © 2015 Elsevier Ltd. All rights reserved.

Helium the disappearing element

CERN Document Server

Sears, Wheeler M

2015-01-01

The subject of the book is helium, the element, and its use in myriad applications including MRI machines, particle accelerators, space telescopes, and of course balloons and blimps. It was at the birth of our Universe, or the Big Bang, where the majority of cosmic helium was created; and stellar helium production continues. Although helium is the second most abundant element in the Universe, it is actually quite rare here on Earth and only exists because of radioactive elements deep within the Earth. This book includes a detailed history of the discovery of helium, of the commercial industry built around it, how the helium we actually encounter is produced within the Earth, and the state of the helium industry today. The gas that most people associate with birthday party balloons is running out. “Who cares?” you might ask. Well, without helium, MRI machines could not function, rockets could not go into space, particle accelerators such as those used by CERN could not operate, fiber optic cables would not...

Hyperpolarized 3-helium MR imaging of the lungs: testing the concept of a central production facility

International Nuclear Information System (INIS)

Beek, E.J.R. van; Schmiedeskamp, J.; Filbir, F.; Heil, W.; Wolf, M.; Otten, E.; Wild, J.M.; Paley, M.N.J.; Fichele, S.; Woodhouse, N.; Swift, A.; Knitz, F.; Mills, G.H.

2003-01-01

The aim of this study was to test the feasibility of a central production facility with distribution network for implementation of hyperpolarized 3-helium MRI. The 3-helium was hyperpolarized to 50-65% using a large-scale production facility based at a university in Germany. Using a specially designed transport box, containing a permanent low-field shielded magnet and dedicated iron-free glass cells, the hyperpolarized 3-helium gas was transported via airfreight to a university in the UK. At this location, the gas was used to perform in vivo MR experiments in normal volunteers and patients with chronic obstructive lung diseases. Following initial tests, the transport (road-air-road cargo) was successfully arranged on six occasions (approximately once per month). The duration of transport to imaging averaged 18 h (range 16-20 h), which was due mainly to organizational issues such as working times and flight connections. During the course of the project, polarization at imaging increased from 20% to more than 30%. A total of 4 healthy volunteers and 8 patients with chronic obstructive pulmonary disease were imaged. The feasibility of a central production facility for hyperpolarized 3-helium was demonstrated. This should enable a wider distribution of gas for this novel technology without the need for local start-up costs. (orig.)

Construction and performance of large flash chambers

International Nuclear Information System (INIS)

Taylor, F.E.; Bogert, D.; Fisk, R.; Stutte, L.; Walker, J.K.; Wolfson, J.; Abolins, M.; Ernwein, J.; Owen, D.; Lyons, T.

1979-01-01

The construction and performance of 12' x 12' flash chambers used in a 340 ton neutrino detector under construction at Fermilab is described. The flash chambers supply digital information with a spatial resolution of 0.2'', and are used to finely sample the shower development of the reaction products of neutrino interactions. The flash chambers are easy and inexpensive to build and are electronically read out

Canada's helium output rising fast

Energy Technology Data Exchange (ETDEWEB)

1966-12-01

About 12 months from now, International Helium Limited will be almost ready to start up Canada's second helium extraction plant at Mankota, in Saskatchewan's Wood Mountain area about 100 miles southwest of Moose Jaw. Another 80 miles north is Saskatchewan's (and Canada's) first helium plant, operated by Canadian Helium and sitting on a gas deposit at Wilhelm, 9 miles north of Swift Current. It contains almost 2% helium, some COD2U, and the rest nitrogen. One year in production was apparently enough to convince Canadian Helium that the export market (it sells most of its helium in W. Europe) can take a lot more than it's getting. Construction began this summer on an addition to the Swift Current plant that will raise its capacity from 12 to 36MMcf per yr when it goes on stream next spring. Six months later, International Helium's 40 MMcf per yr plant to be located about 4 miles from its 2 Wood Mountain wells will double Canada's helium output again.

Low energy helium ion irradiation induced nanostructure formation on tungsten surface

International Nuclear Information System (INIS)

Al-Ajlony, A.; Tripathi, J.K.; Hassanein, A.

2017-01-01

We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10 24 –1.6 × 10 25 ions m −2 ), and flux (2.0 × 10 20 –5.5 × 10 20 ion m −2 s −1 ). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

A comparison of colour, shape, and flash induced illusory line motion.

Science.gov (United States)

Hamm, Jeff P

2017-04-01

When a bar suddenly appears between two boxes, the bar will appear to shoot away from the box that matches it in colour or in shape-a phenomenon referred to as attribute priming of illusory line motion (ILM; colour ILM and shape ILM, respectively). If the two boxes are identical, ILM will still occur away from a box if it changes luminance shortly before the presentation of the bar ( flash ILM). This flash condition has been suggested to produce the illusory motion due to the formation of an attentional gradient surrounding the flashed location. However, colour ILM and shape ILM cannot be explained by an attentional gradient as there is no way for attention to select the matching box prior to the presentation of the bar. These findings challenge the attentional gradient explanation for ILM, but only if it is assumed that ILM arises for the same underlying reason. Two experiments are presented that address the question of whether or not flash ILM is the same as colour ILM or shape ILM. The results suggest that while colour ILM and shape ILM reflect a common illusion, flash ILM arises for a different reason. Therefore, the attentional gradient explanation for flash ILM is not refuted by the occurrence of colour ILM or shape ILM, which may reflect transformational apparent motion (TAM).

Thermal energy distribution analysis for hydrogen production in RGTT200K conceptual design

International Nuclear Information System (INIS)

Tumpal Pandiangan; Ign Djoko Irianto

2011-01-01

RGTT200K is a high temperature gas-cooled reactor (HTGR) which conceptually designed for power generation, hydrogen production and desalination. Hydrogen production process in this design uses thermochemical method of Iodine-Sulphur. To increase the thermal conversion efficiency in hydrogen production installations, it needs to design a thermal energy distribution and temperature associated with the process of thermo-chemical processes in the method of Iodine-Sulphur. In this method there are 7 kinds of processes: (i) H 2 SO4 decomposition reaction (ii) treatment of vaporization (iii) treatment of pre vaporizer (iv) treatment of flash 4 (v) treatment of decomposition of HI (vi) treatment of the flash 1-3 and (vii) Bunsen reaction. To regulate the distribution of energy and temperature appropriate to the needs of each process used 3 pieces of heat exchanger (HE). Calculation of energy distribution through the distribution of helium gas flow has been done with Scilab application programs, so that can know the distribution of thermal energy for production of 1 mole of hydrogen. From this model, it can calculate the thermal energy requirement for production of hydrogen at the desired capacity. In the conceptual design of RGTT200K, helium discharge has been designed by 20 kg/s, so that an efficient hydrogen production capacity needed to produce 15347.8 for 21.74 mole of H 2 . (author)

Flashing light in microalgae biotechnology.

Science.gov (United States)

Abu-Ghosh, Said; Fixler, Dror; Dubinsky, Zvy; Iluz, David

2016-03-01

Flashing light can enhance photosynthesis and improve the quality and quantity of microalgal biomass, as it can increase the products of interest by magnitudes. Therefore, the integration of flashing light effect into microalgal cultivation systems should be considered. However, microalgae require a balanced mix of the light/dark cycle for higher growth rates, and respond to light intensity differently according to the pigments acquired or lost during the growth. This review highlights recently published results on flashing light effect on microalgae and its applications in biotechnology, as well as the recently developed bioreactors designed to fulfill this effect. It also discusses how this knowledge can be applied in selecting the optimal light frequencies and intensities with specific technical properties for increasing biomass production and/or the yield of the chemicals of interest by microalgae belonging to different genera. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of low levels of krypton in helium by gas chromatography

International Nuclear Information System (INIS)

Evans, D.L.; Mukherji, A.K.

1980-01-01

Krypton-helium mixture was used as an adsorbate for surface area measurement--. The surface area measurements depend on the accuracy with which the krypton concentration is known. Generally gas tanks supplied by Union Carbide provide a nominal value of 0.1% krypton in helium. The surface area measurements require, however, that the krypton concentraion be known to +- 0.001% or better. A standard plot of krypton volume in microliters vs the area under the curve as measured by a planimeter using the helium detector and Molecular Sieve 5A column was obtained. Results with a thermal conductivity detector using Molecular Sieve 5A and Carbon Molecular Sieve are also given. Low levels of krypton in helium can be measured with precision using either a helium or a thermal conductivity detector with Molecular Sieve 5A or Carbon Molecular Sieve columns. 2 figures, 1 table

Helium hammer in superfluid transfer

Science.gov (United States)

Tward, E.; Mason, P. V.

1984-01-01

Large transient pressure pulses, referred to as a helium hammer, which occurred in the transfer line of the main cryogenic tank during the development tests of the Infrared Astronomical Satellite, launched on January 25, 1983, are analyzed, and the measures taken to prevent a failure described. The modifications include an installation of a 2.3-liter surge tank upstream, and a back-up relief valve downstream, of a burst disk. The surge tank is designed to attenuate a 0.33-MPa pressure pulse at the inlet down to 0.092 MPa at the outlet. A mechanism of the pulse generation is suggested, which involves flashing and rapid recondensation of the small amount of liquid entering the warm section of a transition to room temperature.

Study on cryogenic adsorption capability of trace nitrogen and methane by activated carbon for cooIant helium purification

International Nuclear Information System (INIS)

Chang Hua; Wu Zongxin

2014-01-01

A fixed-bed apparatus with dynamic two-route proportional gas mixing system was designed to investigate the cryogenic adsorption behavior of nitrogen and methane on activated carbon for designing the helium purification system of high-temperature gas-cooled reactors (HTGR). With helium as carrier gas and at the impurity partial pressure of tens Pa, experiments were performed at near atmospheric pressure and by dynamic column breakthrough method at -196°C. The breakthrough curves and desorption curves were measured. By analyzing the breakthrough curve, both the equilibrium adsorption capacity and the kinetic adsorption capacity at breakthrough point were determined. Based on mass-transfer zone model, the experimental breakthrough curves were analyzed. (author)

Influence of carbon source on alpha-amylase production by Aspergillus oryzae

DEFF Research Database (Denmark)

Carlsen, Morten; Nielsen, Jens

2001-01-01

on sucrose, fructose, glycerol, mannitol and acetate. During growth on acetate there was no production of alpha -amylase, whereas addition of small amounts of glucose resulted in alpha -amylase production. A possible induction by alpha -methyl-D-glucoside during growth on glucose was also investigated......, but this compound was not found to be a better inducer of alpha -amylase production than glucose. The results strongly indicate that besides acting as a repressor via the CreA protein, glucose acts as an inducer.......The influence of the carbon source on a-amylase production by Aspergillus oryzae was quantified in carbon-limited chemostat cultures. The following carbon sources were investigated: maltose, maltodextrin (different chain lengths), glucose, fructose, galactose, sucrose, glycerol, mannitol...

Validation of the RELAP5 code for the modeling of flashing-induced instabilities under natural-circulation conditions using experimental data from the CIRCUS test facility

Energy Technology Data Exchange (ETDEWEB)

Kozmenkov, Y. [Helmholtz-Zentrum Dresden-Rossendorf e.V. (FZD), Institute of Safety Research, P.O.B. 510119, D-01324 Dresden (Germany); Institute of Physics and Power Engineering, Obninsk (Russian Federation); Rohde, U., E-mail: U.Rohde@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf e.V. (FZD), Institute of Safety Research, P.O.B. 510119, D-01324 Dresden (Germany); Manera, A. [Paul Scherrer Institute (Switzerland)

2012-02-15

Highlights: Black-Right-Pointing-Pointer We report about the simulation of flashing-induced instabilities in natural circulation systems. Black-Right-Pointing-Pointer Flashing-induced instabilities are of relevance for operation of pool-type reactors of small power at low pressure. Black-Right-Pointing-Pointer The RELAP5 code is validated against measurement data from natural circulation experiments. Black-Right-Pointing-Pointer The magnitude and frequency of the oscillations were reproduced in good agreement with the measurement data. - Abstract: This paper reports on the use of the RELAP5 code for the simulation of flashing-induced instabilities in natural circulation systems. The RELAP 5 code is intended to be used for the simulation of transient processes in the Russian RUTA reactor concept operating at atmospheric pressure with forced convection of coolant. However, during transient processes, natural circulation with flashing-induced instabilities might occur. The RELAP5 code is validated against measurement data from natural circulation experiments performed within the framework of a European project (NACUSP) on the CIRCUS facility. The facility, built at the Delft University of Technology in The Netherlands, is a water/steam 1:1 height-scaled loop of a typical natural-circulation-cooled BWR. It was shown that the RELAP5 code is able to model all relevant phenomena related to flashing induced instabilities. The magnitude and frequency of the oscillations were reproduced in a good agreement with the measurement data. The close correspondence to the experiments was reached by detailed modeling of all components of the CIRCUS facility including the heat exchanger, the buffer vessel and the steam dome at the top of the facility.

Production of negative helium ions

International Nuclear Information System (INIS)

Toledo, A.S. de; Sala, O.

1977-01-01

A negative helium ion source using potassium charge exchange vapor has been developed to be used as an injector for the Pelletron accelerator. 3 He and α beam currents of up to 2μA have been extracted with 75% particle transmission through the machine [pt

Low energy helium ion irradiation induced nanostructure formation on tungsten surface

Energy Technology Data Exchange (ETDEWEB)

Al-Ajlony, A., E-mail: montaserajlony@yahoo.com; Tripathi, J.K.; Hassanein, A.

2017-05-15

We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10{sup 24}–1.6 × 10{sup 25} ions m{sup −2}), and flux (2.0 × 10{sup 20}–5.5 × 10{sup 20} ion m{sup −2} s{sup −1}). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

International Nuclear Information System (INIS)

Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton

2017-01-01

We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.

Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

International Nuclear Information System (INIS)

Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

2012-01-01

The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

Thermal-hydraulics stability of natural circulation BWR under startup. Flashing effects

International Nuclear Information System (INIS)

Hu, Rui; Kazimi, Mujid S.

2009-01-01

To help achieve the necessary natural circulation flow, a fairly long chimney is installed in a boiling natural circulation reactor like the ESBWR. In such systems, thermal-hydraulic stability during low pressure start-up should be examined while considering the flashing induced by the pressure drop in the channel and the chimney due to gravity head. In this work, a BWR stability analysis code in the frequency domain, named FISTAB (Flashing-Induced STability Analysis for BWR), was developed to address the issue of flashing-induced instability. A thermal-hydraulics non-homogeneous equilibrium model (NHEM) based on a drift flux formulation along with a lumped fuel dynamics model is incorporated in the work. The vapor generation rate is derived from the mixture energy conservation equation while considering the effect of flashing. The functionality of the FISTAB code was confirmed by comparison to experimental results from SIRIUS-N facility at CRIEPI, Japan. Both stationary and perturbation results agree well with the experimental results. (author)

Rotary magnetic refrigerator for superfluid helium production

International Nuclear Information System (INIS)

Hakuraku, Y.; Ogata, H.

1986-01-01

A new rotary-magnetic refrigerator designed to obtain superfluid helium temperatures by executing a magnetic Carnot cycle is developed. A rotor containing 12 magnetic refrigerants (gadolinium-gallium-garnet) is immersed in liquid helium at 4.2 K and rotated at constant speed in a steady magnetic field distribution. Performance tests demonstrate that the new rotary refrigerator is capable of obtaining a temperature of 1.48 K. The maximum useful cooling power obtained at 1.8 K is 1.81 W which corresponds to a refrigeration efficiency of 34%

Fatigue behavior of Type 316 stainless steel following neutron irradiation inducing helium

International Nuclear Information System (INIS)

Grossbeck, M.L.; Liu, K.C.

1980-01-01

Since a tokamak reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially in the first wall and blanket. There has been limited work on fatigue in irradiated alloys but none on irradiated materials containing significant amounts of irradiation-induced helium. To provide scoping data and to study the effects of irradiation on fatigue behavior, 20%-cold-worked type 316 stainless steel from the MFE reference heat was studied

Terrestrial gamma-ray flash production by lightning

Science.gov (United States)

Carlson, Brant E.

Terrestrial gamma-ray flashes (TGFs) are brief flashes of gamma-rays originating in the Earth's atmosphere and observed by satellites. First observed in 1994 by the Burst And Transient Source Experiment on board the Compton Gamma-Ray Observatory, TGFs consist of one or more ˜1 ms pulses of gamma-rays with a total fluence of ˜1/cm2, typically observed when the satellite is near active thunderstorms. TGFs have subsequently been observed by other satellites to have a very hard spectrum (harder than dN/d E ∝ 1/ E ) that extends from below 25 keV to above 20 MeV. When good lightning data exists, TGFs are closely associated with measurable lightning discharge. Such discharges are typically observed to occur within 300 km of the sub-satellite point and within several milliseconds of the TGF observation. The production of these intense energetic bursts of photons is the puzzle addressed herein. The presence of high-energy photons implies a source of bremsstrahlung, while bremsstrahlung implies a source of energetic electrons. As TGFs are associated with lightning, fields produced by lightning are naturally suggested to accelerate these electrons. Initial ideas about TGF production involved electric fields high above thunderstorms as suggested by upper atmospheric lightning research and the extreme energies required for lower-altitude sources. These fields, produced either quasi-statically by charges in the cloud and ionosphere or dynamically by radiation from lightning strokes, can indeed drive TGF production, but the requirements on the source lightning are too extreme and therefore not common enough to account for all existing observations. In this work, studies of satellite data, the physics of energetic electron and photon production, and consideration of lightning physics motivate a new mechanism for TGF production by lightning current pulses. This mechanism is then developed and used to make testable predictions. TGF data from satellite observations are compared

Charged condensate and helium dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Gabadadze, Gregory; Rosen, Rachel A, E-mail: gg32@nyu.edu, E-mail: rar339@nyu.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

2008-10-15

White dwarf stars composed of carbon, oxygen and heavier elements are expected to crystallize as they cool down below certain temperatures. Yet, simple arguments suggest that the helium white dwarf cores may not solidify, mostly because of zero-point oscillations of the helium ions that would dissolve the crystalline structure. We argue that the interior of the helium dwarfs may instead form a macroscopic quantum state in which the charged helium-4 nuclei are in a Bose-Einstein condensate, while the relativistic electrons form a neutralizing degenerate Fermi liquid. We discuss the electric charge screening, and the spectrum of this substance, showing that the bosonic long-wavelength fluctuations exhibit a mass gap. Hence, there is a suppression at low temperatures of the boson contribution to the specific heat-the latter being dominated by the specific heat of the electrons near the Fermi surface. This state of matter may have observational signatures.

Further study of helium production at large impact parameters in 6.4 TeV 32S emulsion reactions

International Nuclear Information System (INIS)

Kamel, S.

1999-01-01

Further study of helium production in electromagnetic and inelastic peripheral interactions of 32 S nuclei at 200 AGeV in nuclear emulsion is presented. The multiplicities, transverse momentum distributions of relativistic He fragments, and their parameters in both interactions are measured. The effect of the multiple helium production on the present obtained evidence of two different temperatures is investigated. The main characteristics of transverse momentum distributions show a certain dependence on the peripherality degree of the interactions

Flow-induced and acoustically induced vibration experience in operating gas-cooled reactors

International Nuclear Information System (INIS)

Halvers, L.J.

1977-03-01

An overview has been presented of flow-induced and acoustically induced vibration failures that occurred in the past in gas-cooled graphite-moderated reactors, and the importance of this experience for the Gas-Cooled Fast-Breeder Reactor (GCFR) project has been assessed. Until now only failures in CO 2 -cooled reactors have been found. No problems with helium-cooled reactors have been encountered so far. It is shown that most of the failures occurred because flow-induced and acoustically induced dynamic loads were underestimated, while at the same time not enough was known about the influence of environmental parameters on material behavior. All problems encountered were solved. The comparison of the influence of the gas properties on acoustically induced and flow-induced vibration phenomena shows that the interaction between reactor design and the thermodynamic properties of the primary coolant precludes a general preference for either carbon dioxide or helium. The acoustic characteristics of CO 2 and He systems are different, but the difference in dynamic loadings due to the use of one rather than the other remains difficult to predict. A slight preference for helium seems, however, to be justified

Helium 3 precipitation in AISI 316L stainless steel induced by radioactive decay of tritium: Microstructural study of helium bubble precipitation

International Nuclear Information System (INIS)

Brass, A.M.; Chene, J.

1994-01-01

The development of the thermonuclear technology has given rise to a renewed interest in the study of the behavior of helium in metals. A great amount of work is still required for the understanding of the role of helium on the mechanical properties of structural materials for fusion technology, especially austenitic stainless steels. This article deals with the study of the influence of thermomechanical heat treatments, aging conditions (temperature and time), and helium concentration of helium bubble precipitation in a 316L austenitic steel. Helium was generated by the radioactive decay of tritium (tritium trick). Helium bubbles impede the grain growth in 316L steel aged at 1,373 K and also the recrystallization reaction at this temperature if cold working is performed prior to aging. Transmission electron microscopy (TEM) observations indicated a weak helium precipitation at 1,073 and 1,223 K, presumably due to the presence of trapping sites for tritium, and no bubble growth after aging up to 100 hours. Precipitation sites are mainly dislocations in the matrix at 1,073 K and grain boundaries and individual dislocations in the matrix at 1,223 K. The large bubble size (50 nm) observed at 1,373 K, even for short aging times (0.083), can partly be attributed to bubble dragging by dislocations toward the grain boundaries. Cold deformation prior to aging leads to a larger bubble size due to growth enhancement during recrystallization. Decreasing the helium content leads to a smaller helium bubble size and density. Tritium trapping at helium bubbles may favor helium 3 accumulation on defects such as grain boundaries, as observed by tritium autoradiography

The IAEA co-ordinated research programme on improvement of measurements, theoretical computations and evaluations of neutron induced helium production cross sections. Status report. Prepared at the final CRP meeting in Sendai, Japan 25-29 September 1995

International Nuclear Information System (INIS)

Pashchenko, A.B.

1996-12-01

The present report describes the results of the IAEA Co-ordinated Research Programme (CRP) on ''Improvements of Measurements, Theoretical Computation and Evaluations of Neutron Induced Helium Production Cross Sections''. Summarized is the progress achieved under the CRP in the following areas: measurements of α-production cross sections for structural materials, theoretical computations at (nα) cross sections; measurements of activation cross sections; and improvement of experimental methods for (n,α) investigations. The status report gives also short summaries on the work of each laboratory which contributed to the results of the CRP. Attached is the list of program members and participants of CRP meetings. (author). Refs, 2 figs, 1 tab

Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

International Nuclear Information System (INIS)

Beeler, J.R. Jr.; Beeler, M.F.

1979-06-01

This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions

Computer experiment studies on mechanisms for irradiation induced defect production and annealing processes. Final report

Energy Technology Data Exchange (ETDEWEB)

Beeler, J.R. Jr.; Beeler, M.F.

1979-06-01

This research is based on pair potentials used in the Brookhaven work. It extends their use in defect production simulations to the 5 MeV range and characterizes the short term annealing of the primary defect states. Defect properties and interactions are studied. Defect interactions include carbon, helium, and misfit metallic substitutional impurity interactions with vacancy and interstitial defects as well as vacancy-vacancy, interstitial-interstitial and vacancy-interstitial interactions. (FS)

Organ protection by the noble gas helium

NARCIS (Netherlands)

Smit, K.F.

2017-01-01

The aims of this thesis were to investigate whether helium induces preconditioning in humans, and to elucidate the mechanisms behind this possible protection. First, we collected data regarding organ protective effects of noble gases in general, and of helium in particular (chapters 1-3). In chapter

Flash mob as a tool of marketing. The use of a crowd psychology in promotion of institutions and products of culture

Directory of Open Access Journals (Sweden)

Magdelena Józefa Cyrklaff

2014-12-01

Full Text Available Flash mobinits original formmeantspontaneous event, initiated in a public space byan unknown groupof people. Ithadentertainingand absurdcharacter and about the time of its commencement completely random people were reported usually through e-mails or text messages. Over time, this particular form of happening evolved and can now be used as an educational tool for sensitizing activation of some important social issues, as well as a marketing tool used in advertising and branding. This article is devoted to the characteristic of flash mobs as a tools of promotion of the institutions, services and cultural products. At the beginning in the article were described the evolution and structure of flash mobs and then were given examples of flash mobs in marketing activities in the field of art and culture. At the end of the article were presented guidelines related to the use of flash mobsin a business field.

Use of Activated Carbon in Packaging to Attenuate Formaldehyde-Induced and Formic Acid-Induced Degradation and Reduce Gelatin Cross-Linking in Solid Dosage Forms.

Science.gov (United States)

Colgan, Stephen T; Zelesky, Todd C; Chen, Raymond; Likar, Michael D; MacDonald, Bruce C; Hawkins, Joel M; Carroll, Sophia C; Johnson, Gail M; Space, J Sean; Jensen, James F; DeMatteo, Vincent A

2016-07-01

Formaldehyde and formic acid are reactive impurities found in commonly used excipients and can be responsible for limiting drug product shelf-life. Described here is the use of activated carbon in drug product packaging to attenuate formaldehyde-induced and formic acid-induced drug degradation in tablets and cross-linking in hard gelatin capsules. Several pharmaceutical products with known or potential vulnerabilities to formaldehyde-induced or formic acid-induced degradation or gelatin cross-linking were subjected to accelerated stability challenges in the presence and absence of activated carbon. The effects of time and storage conditions were determined. For all of the products studied, activated carbon attenuated drug degradation or gelatin cross-linking. This novel use of activated carbon in pharmaceutical packaging may be useful for enhancing the chemical stability of drug products or the dissolution stability of gelatin-containing dosage forms and may allow for the 1) extension of a drug product's shelf-life when the limiting attribute is a degradation product induced by a reactive impurity, 2) marketing of a drug product in hotter and more humid climatic zones than currently supported without the use of activated carbon, and 3) enhanced dissolution stability of products that are vulnerable to gelatin cross-linking. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

First-Principles Molecular Dynamics Study on Helium- filled Carbon Nanotube

International Nuclear Information System (INIS)

Agusta, M K; Prasetiyo, I; Saputro, A G; Dipojono, H K; Maezono, R

2016-01-01

Investigation on carbon nanotube (CNT) filled by Helium (He) atoms is conducted using Density Functional Theory and Molecular Dynamics Simulation. It reveals that He atom is repelled by CNT's wall and find its stable position at the tube center. Vibrational analysis on modes corespond to radial inward and outward breathing movement of CNT shows that He filling tends to pull the CNT wall in inward direction. Furthermore, examination on C-C stretch mode reveals that the existence of He improve the stiffness of CNT's wall. Molecular dynamics calculations which are done on (3,3) and (5,5) nanotube with 0.25 gr/cm 3 and 0.5 gr/cm 3 He density at 300 K and 1500 K confirms the increase of stiffness of CNT wall by interaction with He atoms. Effects of variation of chirality, temperature and He density on CNT wall stiffness is also reported. (paper)

Observers can reliably identify illusory flashes in the illusory flash paradigm

NARCIS (Netherlands)

Erp, J.B.F. van; Philippi, T.G.; Werkhoven, P.

2013-01-01

In the illusory flash paradigm, a single flash may be experienced as two flashes when accompanied by two beeps or taps, and two flashes may be experienced as a single flash when accompanied by one beep or tap. The classic paradigm restricts responses to '1' and '2' (2-AFC), ignoring possible

Helium implanted AlHf as studied by 181 Ta TDPAC

Indian Academy of Sciences (India)

Measurements on helium implanted sample indicate the binding of helium associated defects by Hf solute clusters. Isochronal annealing measurements indicate the dissociation of the helium implantation induced defects from Hf solute clusters for annealing treatments beyond 650 K. On comparison of the present results ...

Damage, trapping and desorption at the implantation of helium and deuterium in graphite, diamond and silicon carbide

International Nuclear Information System (INIS)

Lopez, G.A.R.

1995-07-01

The production, thermal stability and structure of ion induced defects have been studied by Rutherford backscattering in channeling geometry for the implantation of helium and deuterium in graphite, diamond and silicon carbide with energies of 8 and 20 keV. At the implantation of deuterium and helium ions more defects were measured in graphite than in diamond or silicon carbide at equal experimental conditions. This is due to increased backscattering in graphite, which is caused by the splitting and tilting of crystallites and a local reordering of lattice atoms around defects. At 300 K, Helium produces more defects in all three materials than deuterium with equal depth distribution of defects. The ratio of the defects produced by helium and deuterium agrees very well with the corresponding ratio of the energy deposited in nuclear collisions. In graphite, only small concentrations of deuterium induced defects anneal below 800 K, while in diamond small concentrations of deuterium as well as of helium induced defects anneal mostly below 800 K. This annealing behavior is considered to be due to recombination of point defects. The buildup of helium and deuterium in graphite is different. The trapping of deuterium proceeds until saturation is reached, while in the case of helium trapping is interrupted by flaking. In diamond, deuterium as well as helium are trapped almost completely until at higher fluences reemission starts and saturation is reached. Two desorption mechanisms were identified for the thermal desorption of helium from base-oriented graphite. Helium implanted at low fluences desorbs diffusing to the surface, while for the implantation of high fluences the release of helium due to blistering dominates. The desorption of deuterium from graphite and diamond shows differences. While in graphite the desorption starts already at 800 K, in diamond up to 1140 K only little desorption can be observed. These differences can be explained by the different transport

Hot Flashes

Science.gov (United States)

Hot flashes Overview Hot flashes are sudden feelings of warmth, which are usually most intense over the face, neck and chest. Your skin might redden, as if you're blushing. Hot flashes can also cause sweating, and if you ...

Electron attachment and electron ionization of acetic acid clusters embedded in helium nanodroplets

NARCIS (Netherlands)

da Silva, F. Ferreira; Jaksch, S.; Martins, G.; Dang, H. M.; Dampc, M.; Denifl, S.; Maerk, T. D.; Limao-Vieira, P.; Liu, J.; Yang, S.; Ellis, A. M.; Scheier, P.

2009-01-01

The effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic products ejected into the gas phase are detected by mass spectrometry. The cation chemistry (induced by

Dipole moments of molecules solvated in helium nanodroplets

International Nuclear Information System (INIS)

Stiles, Paul L.; Nauta, Klaas; Miller, Roger E.

2003-01-01

Stark spectra are reported for hydrogen cyanide and cyanoacetylene solvated in helium nanodroplets. The goal of this study is to understand the influence of the helium solvent on measurements of the permanent electric dipole moment of a molecule. We find that the dipole moments of the helium solvated molecules, calculated assuming the electric field is the same as in vacuum, are slightly smaller than the well-known gas-phase dipole moments of HCN and HCCCN. A simple elliptical cavity model quantitatively accounts for this difference, which arises from the dipole-induced polarization of the helium

Interdiffusion of krypton and xenon in high-pressure helium

International Nuclear Information System (INIS)

Campana, R.J.; Jensen, D.D.; Epstein, B.D.; Hudson, R.G.; Baldwin, N.L.

1980-01-01

The interdiffusion of gaseous fission products in high-pressure helium is an important factor in the control of radioactivity in gas-cooled fast breeder reactors (GCFRs). As presently conceived, GCFRs use pressure-equalized and vented fuel in which fission gases released from the solid matrix oxide fuel are transported through the fuel rod interstices and internal fission product traps to the fuel assembly vents, where they are swept away to external traps and storage. Since the predominant transport process under steady-state operating conditions is interdiffusion of gaseous fission products in helium, the diffusion properties of krypton-helium and xenon-helium couples have been measured over the range of GCFR temperature and pressure conditions ( -1 ) and expected temperature dependence to the 1.66 power (Tsup(1.66)) at lower pressures and temperatures. Additional work is in progress to measure the behaviour of the krypton-helium and xenon-helium couples in GCFR fuel rod charcoal delay traps. (author)

Temperature dependence of helium-implantation-induced lattice swelling in polycrystalline tungsten: X-ray micro-diffraction and Eigenstrain modelling

International Nuclear Information System (INIS)

Broglie, I. de; Beck, C.E.; Liu, W.; Hofmann, F.

2015-01-01

Using synchrotron X-ray micro-diffraction and Eigenstrain analysis the distribution of lattice swelling near grain boundaries in helium-implanted polycrystalline tungsten is quantified. Samples heat-treated at up to 1473 K after implantation show less uniform lattice swelling that varies significantly from grain to grain compared to as-implanted samples. An increase in lattice swelling is found in the vicinity of some grain boundaries, even at depths beyond the implanted layer. These findings are discussed in terms of the evolution of helium-ion-implantation-induced defects

Production and measurement of dispersion aerosols; application to the transport of deuteron-induced and 84Kr-induced reaction recoils

International Nuclear Information System (INIS)

Schmidt-Ott, W.-D.; Dincklage, R.-D. von

1977-01-01

Dispersion aerosols were produced from various fluids and mixed with helium, nitrogen, and air. The diameter of the aerosols was estimated from their deflection in a low density micro-jet. These two-phase flows were tested for their transport performance for recoils of deuteron-induced reactions at the Goettingen cyclotron. Transport yields of 70%, 90% and 86% were measured when using n-decane with helium, nitrogen, and air, respectively. In comparison to the earlier use of ethylene the amount of disturbing activity induced on the gases was much smaller. The effect of aerosol formation by condensation is discussed. The system was applied in electron- and γ-ray spectroscopy of deuteron-induced reaction recoils. The mixture of n-decane and helium was used for the transport of 84 Kr-induced reaction recoils at the Darmstadt UNILAC. (Auth.)

Sintering uranium oxide in the reaction product of hydrogen-carbon dioxide mixtures

International Nuclear Information System (INIS)

De Hollander, W.R.; Nivas, Y.

1975-01-01

Compacted pellets of uranium oxide alone or containing one or more additives such as plutonium dioxide, gadolinium oxide, titanium dioxide, silica, and alumina are heated to 900 to 1599 0 C in the presence of a mixture of hydrogen and carbon dioxide, either alone or with an inert carrier gas and held at the desired temperature in this atmosphere to sinter the pellets. The sintered pellets are then cooled in an atmosphere having an oxygen partial pressure of 10 -4 to 10 -18 atm of oxygen such as dry hydrogen, wet hydrogen, dry carbon monoxide, wet carbon monoxide, inert gases such as nitrogen, argon, helium, and neon and mixtures of ayny of the foregoing including a mixture of hydrogen and carbon dioxide. The ratio of hydrogen to carbon dioxide in the gas mixture fed to the furnace is controlled to give a ratio of oxygen to uranium atoms in the sintered particles within the range of 1.98:1 to about 2.10:1. The water vapor present in the reaction products in the furnace atmosphere acts as a hydrolysis agent to aid removal of fluoride should such impurity be present in the uranium oxide. (U.S.)

Microstructural evolution adjacent to grain boundaries under cascade damage conditions and helium production

DEFF Research Database (Denmark)

Trinkaus, H.; Singh, B.N.; Victoria, M.

1996-01-01

the cascade damage is accompanied by a high helium production rate. It is shown that, in this case, the width of the peak zone is controlled by the (mostly invisible) bubble structure rather than by the (visible) void structure. The reduced swelling relative to that under neutron irradiation is attributed...

The indication of geothermal events by helium and carbon isotopes of hydrothermal fluids in south China

International Nuclear Information System (INIS)

Mao, Xumei; Wang, Yanxin; Yuan, Jianfei

2013-01-01

Helium and carbon isotopes are important indicators for identifying the origin of volatiles dissolved in groundwater. Four thermal springs and another twelve normal springs are hosted by local deep faults in south China, which are considered to have significant connection to deep geothermal activity. Between 4% and 6% mantle He in thermal springs reveals that significant mantle He migration in deep faults can bring a certain amount of energy, along with thermal volatiles, and contribute to thermal spring formation according to 3 He/ 4 He. While δ 13 C reveals that dissolved inorganic carbon in thermal springs is from rock metamorphism that occurred in certain deep crust as geothermal activity, which is potentially the main energy source of the thermal springs. (authors)

The indication of geothermal events by helium and carbon isotopes of hydrothermal fluids in south China

Energy Technology Data Exchange (ETDEWEB)

Mao, Xumei; Wang, Yanxin; Yuan, Jianfei [National Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

2013-07-01

Helium and carbon isotopes are important indicators for identifying the origin of volatiles dissolved in groundwater. Four thermal springs and another twelve normal springs are hosted by local deep faults in south China, which are considered to have significant connection to deep geothermal activity. Between 4% and 6% mantle He in thermal springs reveals that significant mantle He migration in deep faults can bring a certain amount of energy, along with thermal volatiles, and contribute to thermal spring formation according to {sup 3}He/{sup 4}He. While δ{sup 13}C reveals that dissolved inorganic carbon in thermal springs is from rock metamorphism that occurred in certain deep crust as geothermal activity, which is potentially the main energy source of the thermal springs. (authors)

Toward seamless high-resolution flash flood forecasting over Europe based on radar nowcasting and NWP: An evaluation with case studies

Science.gov (United States)

Park, Shinju; Berenguer, Marc; Sempere-Torres, Daniel; Baugh, Calum; Smith, Paul

2017-04-01

Flash floods induced by heavy rain are one of the hazardous natural events that significantly affect human lives. Because flash floods are characterized by their rapid onset, forecasting flash flood to lead an effective response requires accurate rainfall predictions with high spatial and temporal resolution and adequate representation of the hydrologic and hydraulic processes within a catchment that determine rainfall-runoff accumulations. We present extreme flash flood cases which occurred throughout Europe in 2015-2016 that were identified and forecasted by two real-time approaches: 1) the European Rainfall-Induced Hazard Assessment System (ERICHA) and 2) the European Runoff Index based on Climatology (ERIC). ERICHA is based on the nowcasts of accumulated precipitation generated from the pan-European radar composites produced by the EUMETNET project OPERA. It has the advantage of high-resolution precipitation inputs and rapidly updated forecasts (every 15 minutes), but limited forecast lead time (up to 8 hours). ERIC, on the other hand, provides 5-day forecasts based on the COSMO-LEPS NWP simulations updated 2 times a day but is only produced at a 7 km resolution. We compare the products from both systems and focus on showing the advantages, limitations and complementarities of ERICHA and ERIC for seamless high-resolution flash flood forecasting.

Investigation of impurity-helium solid phase decomposition

International Nuclear Information System (INIS)

Boltnev, R.E.; Gordon, E.B.; Krushinskaya, I.N.; Martynenko, M.V.; Pel'menev, A.A.; Popov, E.A.; Khmelenko, V.V.; Shestakov, A.F.

1997-01-01

The element composition of the impurity-helium solid phase (IHSP), grown by injecting helium gas jet, involving Ne, Ar, Kr, and Xe atoms and N 2 molecules, into superfluid helium, has been studied. The measured stoichiometric ratios, S = N H e / N I m, are well over the values expected from the model of frozen together monolayer helium clusters. The theoretical possibility for the freezing of two layers helium clusters is justified in the context of the model of IHSP helium subsystem, filled the space between rigid impurity centers. The process of decomposition of impurity-helium (IH)-samples taken out of liquid helium in the temperature range 1,5 - 12 K and the pressure range 10-500 Torr has been studied. It is found that there are two stages of samples decomposition: a slow stage characterized by sample self cooling and a fast one accompanied by heat release. These results suggest, that the IHSP consists of two types of helium - weakly bound and strongly bound helium - that can be assigned to the second and the first coordination helium spheres, respectively, formed around heavy impurity particles. A tendency for enhancement of IHSP thermo stability with increasing the impurity mass is observed. Increase of helium vapor pressure above the sample causes the improvement of IH sample stability. Upon destruction of IH samples, containing nitrogen atoms, a thermoluminescence induced by atom recombination has been detected in the temperature region 3-4,5 K. This suggests that numerous chemical reactions may be realized in solidified helium

Electron induced formation and stability of molecular and cluster ions in gas phase and superfluid helium nanodroplets

International Nuclear Information System (INIS)

Aleem, M. A.

2010-01-01

The present PhD thesis represents a broad range study of electron induced formation and stability of positive and negative ions in gas phase and superfluid helium nanodroplets. The molecules studied are of industrial, environmental, plasma and biological relevance. The knowledge obtained from the study provides new insight for the proper understanding and control on energetics and dynamics of the reactions involved in the formation and fragmentation processes of the studied molecules and clusters. The experiments are accomplished and investigated using mass spectrometric techniques for the formation of molecular and cluster ions using different mass spectrometers available in our laboratory. One part of the work is focused on electron-induced reactions of the molecules in gas phase. Especially focus is laid to electron attachment to the isomers of mononitrotolouene used as an additive to explosives. The fragile nature and high internal energy of these molecules has lead to extensive fragmentation following the ionisation process. Dissociative electron attachment to the three different isomers has shown different resonances and therefore this process can be utilized to explicitly distinguish these isomers. Anion efficiency curves of the isomers have been studied using effusive molecular beam source in combination with a hemispherical electron monochromator as well as a Nier-type ion source attached to a sector field mass spectrometer. The outcome of the experiment is a reliable and effective detection method highly desirable for environmental and security reasons. Secondly, dissociative electron ionization of acetylene and propene is studied and their data is directly related to the plasma modelling for plasma fusion and processing reactors. Temperature effects for dissociative electron attachment to halo-hydrocarbons are also measured using a trochoidal electron monochromator. The second part of the work is concerned with the investigation of electron-induced

Assignment and analysis of the A3Πi-X3Σ- transition of the CCO molecule. Formation and disappearance of the CCO's X3Σ- state during flash photolysis of the carbon suboxide

International Nuclear Information System (INIS)

Devillers, Claude

1971-01-01

As the C 2 O radical appeared to be the necessary intermediate compound which could lead from atomic carbon to carbon suboxide by a chain of elementary reactions for the study of the effect of radiations on CO, this research thesis, after a recall on the nature of primary compounds of carbon suboxide photolysis, presents experimental techniques aimed at the investigation of C 2 O: flash photolysis to observe it with low resolution, experimental set-up to record its spectrum with a high resolution, experimental set-up to observe it by pulse radiolysis of carbon oxide. The author reports the identification and analysis of the C 2 O spectrum, and discusses the formation and disappearance of the CCO's X 3 Σ - state with or without the presence of sensors during flash photolysis of the carbon suboxide [fr

75 FR 82071 - In the Matter of Certain Flash Memory Chips and Products Containing Same; Notice of Commission...

Science.gov (United States)

2010-12-29

... Memory Chips and Products Containing Same; Notice of Commission Decision Not To Review the ALJ's Final... flash memory chips and products containing the same by reason of infringement of various claims of... practices or exploits the '877 patent does not exist, nor is such an industry in the process of being...

Using hydrocarbon as a carbon source for synthesis of carbon nanotube by electric field induced needle-pulsed plasma

International Nuclear Information System (INIS)

Kazemi Kia, Kaveh; Bonabi, Fahimeh

2013-01-01

In this work different hydrocarbons are used as the carbon source, in the production of carbon nanotubes (CNTs) and nano onions. An electric field induced needle pulse arc-discharge reactor is used. The influence of starting carbon on the synthesis of CNTs is investigated. The production efficiency is compared for Acetone, Isopropanol and Naphthalene as simple hydrocarbons. The hydrocarbons are preheated and then pretreated by electric field before being exposed to plasma. The hydrocarbon vapor is injected into plasma through a graphite spout in the cathode assembly. The pulsed plasma takes place between two graphite rods while a strong electric field has been already established alongside the electrodes. The pulse width is 0.3 μs. Mechanism of precursor decomposition is discussed by describing three forms of energy that are utilized to disintegrate the precursor molecules: thermal energy, electric field and kinetic energy of plasma. Molecular polarity of a hydrocarbon is one of the reasons for choosing carbon raw material as a precursor in an electric field induced low power pulsed-plasma. The results show that in order to obtain high quality carbon nanotubes, Acetone is preferred to Isopropanol and Naphthalene. Scanning probe microscopy techniques are used to investigate the products. - Highlights: • We synthesized CNTs (carbon nano tubes) by needle pulsed plasma. • We use different hydrocarbons as carbon source in the production of CNTs. • We investigated the influence of starting carbon on the synthesis of CNTs. • Thermal energy, electric field and kinetic energy are used to break carbon bonds. • Polar hydrocarbon molecules are more efficient than nonpolar ones in production

Asymptotic strength of thermal pulses in the helium shell burning

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, M Y [Niigata Univ. (Japan); Sugimoto, D

1979-03-01

Secular growth in the strength of the recurrent thermal pulses of helium shell burning is discussed for the purpose of determining its asymptotic strength. It is shown that the pulse grows stronger if the helium zone has been cooled more before the initiation of the pulse. The secular growth of the pulse is related with the increasing degree of cooling. Thermal pulses are computed for an initial model corresponding to the maximum possible cooling, i.e., for a model in which the steady-state entropy distribution was realized in the helium zone. Such thermal pulses are shown to give an upper bound to the asymptotic strength, which is close enough to the asymptotic strength itself for relatively large core masses. Numerical results are given for the core mass of 1.07 M sub(sun), for which the asymptotic strength is found to be 9 x 10/sup 6/ L sub(sun). Thermal pulses are also computed for an initial model which has been cooled artificially more than the steady-state model. The first pulse results in a much greater strength than in the normal model, but a later pulse approaches the normal asymptotic value. Such models are also discussed in relation to the shell flashes on accreting white dwarfs.

Experimental study on methanol recovery through flashing vaporation in continuous production of biodiesel via supercritical methanol

International Nuclear Information System (INIS)

Wang Cunwen; Chen Wen; Wang Weiguo; Wu Yuanxin; Chi Ruan; Tang Zhengjiao

2011-01-01

To improve the oil conversion, high methanol/oil molar ratio is required in the continuous production of biodiesel via supercritical methanol transesterification in tubular reactor. And thus the subsequent excess methanol recovery needs high energy consumption. Based on the feature of high temperature and high pressure in supercritical methanol transesterification, excess methanol recovery in reaction system by flashing vaporation is conducted and the effect of reaction temperature, reaction pressure and flashing pressure on methanol recovery and methanol concentration in gas phase is discussed in detail in this article. Results show that at the reaction pressure of 9-15 MPa and the reaction temperature of 240-300 o C, flashing pressure has significant influence on methanol recovery and methanol content in gas phase, which can be effectively improved by reducing flashing pressure. At the same time, reaction temperature and reaction pressure also have an important effect on methanol recovery and methanol content in gas phase. At volume flow of biodiesel and methanol 1:2, tubular reactor pressure 15 MPa, tubular reactor temperature 300 o C and the flashing pressure 0.4 MPa, methanol recovery is more than 85% and methanol concentration of gas phase (mass fraction) is close to 99% after adiabatic braising; therefore, the condensate liquid of gas phase can be injected directly into methanol feedstock tank to be recycled. Research abstracts: Biodiesel is an important alternative energy, and supercritical methanol transesterification is a new and green technology to prepare biodiesel with some obvious advantages. But it also exists some problems: high reaction temperature, high reaction pressure and large molar ratio of methanol/oil will cause large energy consumption which restricts supercritical methanol for the industrial application of biodiesel. So a set of tubular reactor-coupled flashing apparatus is established for continuous preparing biodiesel in supercritical

Tritium and helium-3 in metals

International Nuclear Information System (INIS)

Lasser, R.

1989-01-01

The book surveys recent results on the behaviour of tritium and its decay product helium-3 metals. In contrast to many earlier books which discuss the properties of the stable hydrogen isotopes without mentioning tritium, this book reviews mainly the results on tritium in metals. Due to the difficulties in preparing metal tritide samples, very important quantities such as diffusivity, superconductivity, solubility, etc. have only been determined very recently. The book not only presents the measured tritium data, but also the isotopic dependency of the different physical properties by comparing H, D and T results. A chapter is devoted to helium-3 in metals. Aspects such as helium release, generation of helium bubbles, swelling, and change of the lattice parameter upon aging are discussed. The book provides the reader with up-to-date information and deep insight into the behaviour of H, D, T and He-3 in metals. Further important topics such a tritium production, its risks, handling and discharge to the environment are also addressed

Literature survey of heat transfer and hydraulic resistance of water, carbon dioxide, helium and other fluids at supercritical and near-critical pressures

Energy Technology Data Exchange (ETDEWEB)

Pioro, I.L.; Duffey, R.B

2003-04-01

This survey consists of 430 references, including 269 Russian publications and 161 Western publications devoted to the problems of heat transfer and hydraulic resistance of a fluid at near-critical and supercritical pressures. The objective of the literature survey is to compile and summarize findings in the area of heat transfer and hydraulic resistance at supercritical pressures for various fluids for the last fifty years published in the open Russian and Western literature. The analysis of the publications showed that the majority of the papers were devoted to the heat transfer of fluids at near-critical and supercritical pressures flowing inside a circular tube. Three major working fluids are involved: water, carbon dioxide, and helium. The main objective of these studies was the development and design of supercritical steam generators for power stations (utilizing water as a working fluid) in the 1950s, 1960s, and 1970s. Carbon dioxide was usually used as the modeling fluid due to lower values of the critical parameters. Helium, and sometimes carbon dioxide, were considered as possible working fluids in some special designs of nuclear reactors. (author)

Flash characteristics of plasma induced by hypervelocity impact

Energy Technology Data Exchange (ETDEWEB)

Zhang, Kai [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Beijing Automotive Technology Center, Beijing 100021 (China); Long, Renrong, E-mail: longrenrong@bit.edu.cn, E-mail: qmzhang@bit.edu.cn; Zhang, Qingming, E-mail: longrenrong@bit.edu.cn, E-mail: qmzhang@bit.edu.cn; Xue, Yijiang; Ju, Yuanyuan [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

2016-08-15

Using a two-stage light gas gun, a series of hypervelocity impact experiments was conducted in which 6.4-mm-diameter spherical 2024-aluminum projectiles impact 23-mm-thick targets made of the same material at velocities of 5.0, 5.6, and 6.3 km/s. Both an optical pyrometer composed of six photomultiplier tubes and a spectrograph were used to measure the flash of the plasma during hypervelocity impact. Experimental results show that, at a projectile velocity of 6.3 km/s, the strong flash lasted about 10 μs and reached a temperature of 4300 K. Based on the known emission lines of AL I, spectral methods can provide the plasma electron temperature. An electron-temperature comparison between experiment and theoretical calculation indicates that single ionization and secondary ionization are the two main ionizing modes at velocities 5.0–6.3 km/s.

Cluster dynamics modeling of the effect of high dose irradiation and helium on the microstructure of austenitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Brimbal, Daniel, E-mail: Daniel.brimbal@areva.com [AREVA NP, Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense (France); Fournier, Lionel [AREVA NP, Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense (France); Barbu, Alain [Alain Barbu Consultant, 6 Avenue Pasteur Martin Luther King, 78230 Le Pecq (France)

2016-01-15

A mean field cluster dynamics model has been developed in order to study the effect of high dose irradiation and helium on the microstructural evolution of metals. In this model, self-interstitial clusters, stacking-fault tetrahedra and helium-vacancy clusters are taken into account, in a configuration well adapted to austenitic stainless steels. For small helium-vacancy cluster sizes, the densities of each small cluster are calculated. However, for large sizes, only the mean number of helium atoms per cluster size is calculated. This aspect allows us to calculate the evolution of the microstructural features up to high irradiation doses in a few minutes. It is shown that the presence of stacking-fault tetrahedra notably reduces cavity sizes below 400 °C, but they have little influence on the microstructure above this temperature. The binding energies of vacancies to cavities are calculated using a new method essentially based on ab initio data. It is shown that helium has little effect on the cavity microstructure at 300 °C. However, at higher temperatures, even small helium production rates such as those typical of sodium-fast-reactors induce a notable increase in cavity density compared to an irradiation without helium. - Highlights: • Irradiation of steels with helium is studied through a new cluster dynamics model. • There is only a small effect of helium on cavity distributions in PWR conditions. • An increase in helium production causes an increase in cavity density over 500 °C. • The role of helium is to stabilize cavities via reduced emission of vacancies.

Condensation of helium in interstitial sites of carbon nanotubes bundles

International Nuclear Information System (INIS)

Marcone, B.; Orlandini, E.; Toigo, F.; Ancilotto, F.

2006-01-01

Helium atoms are believed to be strongly bound within the interstitial channels in bundles of carbon nanotubes. In a recent paper [F. Ancilotto et al., Phys. Rev. B 70, 165422 (2004)] inhomogeneity in the size distribution of nanotube radii was shown to make a system of 4 He atoms in such an environment effectively a four-dimensional Bose gas, thus permitting a Bose-Einstein condensation (BEC) of the adsorbed atoms into the minimum energy state. This surprising result was obtained for a model of noninteracting atoms in a continuum distribution of (virtually) infinite interstitial channels. Here we investigate how the singular thermal properties of the ideal system and the occurrence of BEC are affected by a more realistic modeling of a bundle of nanotubes where (i) the number of nanotubes is finite and where (ii) 4 He atoms adsorbed within the same interstitial channel interact among themselves. Also in this case we observe an anomalous heat capacity close to the ideal condensation temperature, suggesting the persistence of the condensation transition for interacting 4 He atoms, which might be experimentally observed

Helium induced degradation in the weldability of an austenitic stainless steel

International Nuclear Information System (INIS)

Lin, H.T.; Goods, S.H.; Grossbeck, M.L.; Chinl, B.A.

1988-01-01

Autogenous gas tungsten arc welding was performed on He-doped type 316 stainless steel. Helium was uniformly implanted in the material using the ''tritium trick'' to levels of 27 and 105 appm. Severe intergranular cracking occurred in both fusion and heat-affected zones. Microstructural observations of fusion zone indicated that the pore size, degree of porosity, and tendency to form cracks increased with increasing helium concentration. Scanning electron microscopy showed that cracking in He-doped materials was due to the precipitation of helium bubbles on grain boundaries and dentrite interfaces. Results of the present study demonstrate that the use of conventional welding techniques to repair materials degraded by exposure to radiation may be difficult if the irradiation results in the generation of even rather small amounts of helium. 23 refs., 9 figs., 2 tabs

FLASH Interface; a GUI for managing runtime parameters in FLASH simulations

Science.gov (United States)

Walker, Christopher; Tzeferacos, Petros; Weide, Klaus; Lamb, Donald; Flocke, Norbert; Feister, Scott

2017-10-01

We present FLASH Interface, a novel graphical user interface (GUI) for managing runtime parameters in simulations performed with the FLASH code. FLASH Interface supports full text search of available parameters; provides descriptions of each parameter's role and function; allows for the filtering of parameters based on categories; performs input validation; and maintains all comments and non-parameter information already present in existing parameter files. The GUI can be used to edit existing parameter files or generate new ones. FLASH Interface is open source and was implemented with the Electron framework, making it available on Mac OSX, Windows, and Linux operating systems. The new interface lowers the entry barrier for new FLASH users and provides an easy-to-use tool for experienced FLASH simulators. U.S. Department of Energy (DOE), NNSA ASC/Alliances Center for Astrophysical Thermonuclear Flashes, U.S. DOE NNSA ASC through the Argonne Institute for Computing in Science, U.S. National Science Foundation.

Flash photolysis of rhodopsin in the cat retina

International Nuclear Information System (INIS)

Ripps, H.; Mehaffey, L.; Siegel, I.M.; Ernst, W.; Kemp, C.M.

1981-01-01

The bleaching of rhodopsin by short-duration flashes of a xenon discharge lamp was studied in vivo in the cat retina with the aid of a rapid, spectral-scan fundus reflectometer. Difference spectra recorded over a broad range of intensities showed that the bleaching efficacy of high-intensity flashes was less than that of longer duration, steady lights delivering the same amount of energy. Both the empirical results and those derived from a theoretical analysis of flash photolysis indicate that, under the conditions of these experiments, the upper limit of the flash bleaching of rhodopsin in cat is approximately 90%. Although the fact that a full bleach could not be attained is attributable to photoreversal, i.e., the photic regeneration of rhodopsin from its light-sensitive intermediates, the 90% limit is considerably higher than the 50% (or lower) value obtained under other experimental circumstances. Thus, it appears that the duration (approximately 1 ms) and spectral composition of the flash, coupled with the kinetic parameters of the thermal and photic reactions in the cat retina, reduce the light-induced regeneration of rhodopsin to approximately 10%

Automated Studies of Continuing Current in Lightning Flashes

Science.gov (United States)

Martinez-Claros, Jose

Continuing current (CC) is a continuous luminosity in the lightning channel that lasts longer than 10 ms following a lightning return stroke to ground. Lightning flashes following CC are associated with direct damage to power lines and are thought to be responsible for causing lightning-induced forest fires. The development of an algorithm that automates continuing current detection by combining NLDN (National Lightning Detection Network) and LEFA (Langmuir Electric Field Array) datasets for CG flashes will be discussed. The algorithm was applied to thousands of cloud-to-ground (CG) flashes within 40 km of Langmuir Lab, New Mexico measured during the 2013 monsoon season. It counts the number of flashes in a single minute of data and the number of return strokes of an individual lightning flash; records the time and location of each return stroke; performs peak analysis on E-field data, and uses the slope of interstroke interval (ISI) E-field data fits to recognize whether continuing current (CC) exists within the interval. Following CC detection, duration and magnitude are measured. The longest observed C in 5588 flashes was 631 ms. The performance of the algorithm (vs. human judgement) was checked on 100 flashes. At best, the reported algorithm is "correct" 80% of the time, where correct means that multiple stations agree with each other and with a human on both the presence and duration of CC. Of the 100 flashes that were validated against human judgement, 62% were hybrid. Automated analysis detects the first but misses the second return stroke in many cases where the second return stroke is followed by long CC. This problem is also present in human interpretation of field change records.

Mutation induced with ion beam irradiation in rose

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, H. E-mail: yhiroya@nias.affrc.go.jp; Nagatomi, S.; Morishita, T.; Degi, K.; Tanaka, A.; Shikazono, N.; Hase, Y

2003-05-01

The effects of mutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in 'Orange Rosamini' and in plants derived from 10 buds among 61 irradiated buds in 'Red Minimo'. In carbon ion, mutations were observed in plants derived from 12 buds among 88 irradiated buds in 'Orange Rosamini'. Mutations were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly observed. Irradiation with both ion beams induced mutants in the number of petals, in flower size, in flower shape and in flower color in each cultivar.

Helium behaviour in nuclear glasses

International Nuclear Information System (INIS)

Fares, T.

2011-01-01

The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

A new approach to constrain basal helium flux into aquifers for better estimation of groundwater ages by Helium 4

Science.gov (United States)

Matsumoto, Takuya; Sturchio, Neil C.; Chang, Hung K.; Gastmans, Didier; Araguas-Araguas, Luis J.; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yokochi, Reika; Purtschert, Roland; Zongyu, Chen; Shuiming, Hu; Aggarwal, Pradeep K.

2016-04-01

Estimation of groundwater age through the combined use of isotope methods and groundwater flow modelling is the common approach used for developing the required level of knowledge in the case of groundwater pumped from deep aquifers. For more than 50 years radiocarbon and tritium have been the common tools used in isotope hydrology studies to provide first estimates of groundwater age and dynamics. The half-life of carbon-14 (5730 years) and the complex geochemistry of carbon species in most environments have limited the proper characterization of groundwater flow patterns in large sedimentary basins and deep aquifers to ages more recent than about 40 000 years. Over the last years, a number of long-live radionuclides and other isotopes have been tested as more reliable age indicators by specialised laboratories. Among these methods, chlorine-36 (half-life of 300 000 yr) has been used with mixed results, mainly due to problems derived from in-situ production of this radionuclide. Uranium isotopes have also been used in a few instances, but never became a routine tool. Accumulation of helium-4 in deep groundwaters has also been proposed and used in a few instance, but one major obstacle in the 4He dating method is a difficulty in assessing a rate constant of 4He input into aquifers (namely, the entering basal 4He flux). In this context, recent breakthrough developments in analytical methods allow the precise determination of dissolved noble gases in groundwater as well as trace-level noble gas radionuclides present in very old groundwaters. Atom trap trace analysis, or ATTA, has dramatically improved over the last years the processing of very small amount of noble gases, providing now real possibilities for routine measurements of extremely low concentration of exotic radionuclides dissolved in groundwater, such as krypton-81 (half-life 229 000 years). Atom trap trace analysis involves the selective capture of individual atoms of a given isotope using six laser

Dopant-induced ignition of helium nanoplasmas—a mechanistic study

Science.gov (United States)

Heidenreich, Andreas; Schomas, Dominik; Mudrich, Marcel

2017-12-01

Helium (He) nanodroplets irradiated by intense near-infrared laser pulses form a nanoplasma by avalanche-like electron impact ionizations (EIIs) even at lower laser intensities where He is not directly field ionized, provided that the droplets contain a few dopant atoms which provide seed electrons for the EII avalanche. In this theoretical paper on calcium and xenon doped He droplets we elucidate the mechanism which induces ionization avalanches, termed ignition. We find that the partial loss of seed electrons from the activated droplets starkly assists ignition, as the Coulomb barrier for ionization of helium is lowered by the electric field of the dopant cations, and this deshielding of the cation charges enhances their electric field. In addition, the dopant ions assist the acceleration of the seed electrons (slingshot effect) by the laser field, supporting EIIs of He and also causing electron loss by catapulting electrons away. The dopants’ ability to lower the Coulomb barriers at He as well as the slingshot effect decrease with the spatial expansion of the dopant, causing a dependence of the dopants’ ignition capability on the dopant mass. Here, we develop criteria (impact count functions) to assess the ignition capability of dopants, based on (i) the spatial overlap of the seed electron cloud with the He atoms and (ii) the overlap of their kinetic energy distribution with the distribution of Coulomb barrier heights at He. The relatively long time delays between the instants of dopant ionization and ignition (incubation times) for calcium doped droplets are determined to a large extent by the time it takes to deshield the dopant ions.

International Emissions Trading and Induced Carbon-Saving Technical Change : Effects of Restricting the Trade in Carbon Rights

OpenAIRE

Matschoss, Patrick; Welsch, Heinz

2004-01-01

This paper examines the implications of restricting the tradability of carbon rights in the presence of induced technical change. Unlike earlier approaches aiming at exploring the tradability-technology linkage we focus on climate-relevant 'carbon-saving' technical change. This is achieved by incorporating endogenous investment in carbon productivity into the RICE-99 integrated assessment model of Nordhaus and Boyer (2000). Simulation analysis of various emission reduction scenarios with seve...

Helium behaviour in implanted boron carbide

Directory of Open Access Journals (Sweden)

Motte Vianney

2015-01-01

Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

Fission neutron irradiation of copper containing implanted and transmutation produced helium

DEFF Research Database (Denmark)

Singh, B.N.; Horsewell, A.; Eldrup, Morten Mostgaard

1992-01-01

High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K. The distribut......High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K...... as well as the effect of the presence of other transmutation produced impurity atoms in the 800 MeV proton irradiated copper will be discussed....

Helium mobility in advanced nuclear ceramics

International Nuclear Information System (INIS)

Agarwal, Shradha

2014-01-01

The main goal of this work is to improve our knowledge on the mechanisms able to drive the helium behaviour in transition metal carbides and nitrides submitted to thermal annealing or ion irradiation. TiC, TiN and ZrC polycrystals were implanted with 3 MeV 3 He ions at room temperature in the fluence range 2 * 10 15 et 6 * 10 16 cm -2 . Some of them have been pre-irradiated with self-ions (14 MeV Ti or Zr). Fully controlled thermal annealing tests were subsequently carried out in the temperature range 1000 - 1600 C for two hours. The evolution of the helium depth distribution in function of implantation dose, temperature and pre-irradiation dose was measured thanks to the deuteron-induced nuclear reaction 3 He(d, p 0 ) 4 He between 900 keV and 1.8 MeV. The microstructure of implanted and annealed samples was investigated by transmission electron microscopy on thin foils prepared using the FIB technique. Additional characterization tools, as X-ray diffraction and Raman microspectrometry, have been also applied in order to obtain complementary information. Among the most relevant results obtained, the following have to be outlined: - double-peak helium depth profile was measured on as implanted sample for the three compounds. The first peak is located near the end of range and includes the major part of helium, a second peak located close to the surface corresponds to the helium atoms trapped by the native vacancies; - the helium retention capacity in transition metal carbides and nitrides submitted to fully controlled thermal treatments varies according to ZrC 0.92 ≤ TiC 0.96 ≤ TiN 0.96 ; - whatever the investigated material, a self-ion-induced pre-damaging does not modify the initial helium profile extent. The influence of the post-implantation thermal treatment remains preponderant in any case; - the apparent diffusion coefficient of helium is in the range 4 * 10 -18 - 2 * 10 -17 m 2 s -1 in TiC0.96 and 3.5 * 10 -19 - 5.3 * 10 -18 m 2 s -1 in TiN 0.96 between

PENGEMBANGAN MEDIA FLASH BERBASIS PEMBELAJARAN INKUIRI UNTUK MENINGKATKAN HASIL BELAJAR SISWA

Directory of Open Access Journals (Sweden)

Indah Triana Aprillia

2016-01-01

Full Text Available Penelitian ini merupakan penelitian Research and Development (R&D. Tahapan rancangan pengembangan media flash ini menggunakan langkah prosedural oleh Borg and Gall. Tujuan penelitian ini adalah untuk mengetahui keefektifan pada ranah kognitif, afektif dan psikomotorik dalam penggunaan media flash berbasis pembelajaran inkuiri. Pengumpulan data pada penelitian ini menggunakan metode observasi, tes, angket dan dokumentasi. Data hasil penelitian dianalisis menggunakan metode analisis deskriptif kuantitatif. Produk pengembangan dinyatakan valid dan layak apabila telah memenuhi kriteria baik atau sangat baik dari validator. Produk pengembangan teruji untuk meningkatkan hasil belajar siswa yaitu diuji berdasarkan penggunaan media flash pada proses pembelajaran. Hasil pengembangan produk media flash berbasis pembelajaran inkuiri dinyatakan valid dengan kategori baik dan layak diterapkan berdasarkan uji kelayakan oleh ahli media dan ahli materi dengan skor rata-rata ahli media 73.5 dan ahli materi 37. Media flash dinyatakan efektif karena 36 siswa mencapai nilai KKM pada hasil tes, dengan nilai n-gain 0,71 dan pada aspek afektif dan psikomotorik termasuk dalam kategori baik, serta mendapat respon positif dari penggunanya dilihat dari angket tanggapan siswa, sehingga media flash efektif meningkatkan hasil belajar siswa. The research include in Research and Development (R&D. This step of flash media development uses procedural step by Borg and Gall. The purpose of this research is to know the effectiveness in the cognitive, afective, and psychomotoric domain in using flash media based on inquiry learning. Data accumulation in this research uses observation, test, questionaire and documentation methods. The result data of this research is analyzed by using quantitative descriptive analysis method. Development product is called valid and proper if it has fullfilled good or very good criteria from the validator. The development product proved to improve the

The haptic and the visual flash-lag effect and the role of flash characteristics.

Directory of Open Access Journals (Sweden)

Knut Drewing

Full Text Available When a short flash occurs in spatial alignment with a moving object, the moving object is seen ahead the stationary one. Similar to this visual "flash-lag effect" (FLE it has been recently observed for the haptic sense that participants judge a moving hand to be ahead a stationary hand when judged at the moment of a short vibration ("haptic flash" that is applied when the two hands are spatially aligned. We further investigated the haptic FLE. First, we compared participants' performance in two isosensory visual or haptic conditions, in which moving object and flash were presented only in a single modality (visual: sphere and short color change, haptic: hand and vibration, and two bisensory conditions, in which the moving object was presented in both modalities (hand aligned with visible sphere, but the flash was presented only visually or only haptically. The experiment aimed to disentangle contributions of the flash's and the objects' modalities to the FLEs in haptics versus vision. We observed a FLE when the flash was visually displayed, both when the moving object was visual and visuo-haptic. Because the position of a visual flash, but not of an analogue haptic flash, is misjudged relative to a same visuo-haptic moving object, the difference between visual and haptic conditions can be fully attributed to characteristics of the flash. The second experiment confirmed that a haptic FLE can be observed depending on flash characteristics: the FLE increases with decreasing intensity of the flash (slightly modulated by flash duration, which had been previously observed for vision. These findings underline the high relevance of flash characteristics in different senses, and thus fit well with the temporal-sampling framework, where the flash triggers a high-level, supra-modal process of position judgement, the time point of which further depends on the processing time of the flash.

HELIUM ATMOSPHERES ON WARM NEPTUNE- AND SUB-NEPTUNE-SIZED EXOPLANETS AND APPLICATIONS TO GJ 436b

Energy Technology Data Exchange (ETDEWEB)

Hu, Renyu; Yung, Yuk L. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Seager, Sara, E-mail: renyu.hu@jpl.nasa.gov [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2015-07-01

Warm Neptune- and sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptune- and sub-Neptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydrogen, and therefore the escape is heavily affected by diffusive separation between hydrogen and helium. A helium atmosphere can thus be formed—from a primordial hydrogen–helium atmosphere—via atmospheric hydrodynamic escape from the planet. The helium atmosphere has very different abundances of major carbon and oxygen species from those of a hydrogen atmosphere, leading to distinctive transmission and thermal emission spectral features. In particular, the hypothesis of a helium-dominated atmosphere can explain the thermal emission spectrum of GJ 436b, a warm Neptune-sized exoplanet, while also being consistent with the transmission spectrum. This model atmosphere contains trace amounts of hydrogen, carbon, and oxygen, with the predominance of CO over CH{sub 4} as the main form of carbon. With our atmospheric evolution model, we find that if the mass of the initial atmosphere envelope is 10{sup −3} planetary mass, hydrodynamic escape can reduce the hydrogen abundance in the atmosphere by several orders of magnitude in ∼10 billion years. Observations of exoplanet transits may thus detect signatures of helium atmospheres and probe the evolutionary history of small exoplanets.

HELIUM ATMOSPHERES ON WARM NEPTUNE- AND SUB-NEPTUNE-SIZED EXOPLANETS AND APPLICATIONS TO GJ 436b

International Nuclear Information System (INIS)

Hu, Renyu; Yung, Yuk L.; Seager, Sara

2015-01-01

Warm Neptune- and sub-Neptune-sized exoplanets in orbits smaller than Mercury’s are thought to have experienced extensive atmospheric evolution. Here we propose that a potential outcome of this atmospheric evolution is the formation of helium-dominated atmospheres. The hydrodynamic escape rates of Neptune- and sub-Neptune-sized exoplanets are comparable to the diffusion-limited escape rate of hydrogen, and therefore the escape is heavily affected by diffusive separation between hydrogen and helium. A helium atmosphere can thus be formed—from a primordial hydrogen–helium atmosphere—via atmospheric hydrodynamic escape from the planet. The helium atmosphere has very different abundances of major carbon and oxygen species from those of a hydrogen atmosphere, leading to distinctive transmission and thermal emission spectral features. In particular, the hypothesis of a helium-dominated atmosphere can explain the thermal emission spectrum of GJ 436b, a warm Neptune-sized exoplanet, while also being consistent with the transmission spectrum. This model atmosphere contains trace amounts of hydrogen, carbon, and oxygen, with the predominance of CO over CH 4 as the main form of carbon. With our atmospheric evolution model, we find that if the mass of the initial atmosphere envelope is 10 −3 planetary mass, hydrodynamic escape can reduce the hydrogen abundance in the atmosphere by several orders of magnitude in ∼10 billion years. Observations of exoplanet transits may thus detect signatures of helium atmospheres and probe the evolutionary history of small exoplanets

Behaviour of helium after implantation in molybdenum

International Nuclear Information System (INIS)

Viaud, C.; Maillard, S.; Carlot, G.; Valot, C.; Gilabert, E.; Sauvage, T.; Peaucelle, C.; Moncoffre, N.

2009-01-01

This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature

Use of Helium Production to Screen Glow Discharges for Low Energy Nuclear Reactions (LENR)

Science.gov (United States)

Passell, Thomas O.

2011-03-01

My working hypothesis of the conditions required to observe low energy nuclear reactions (LENR) follows: 1) High fluxes of deuterium atoms through interfaces of grains of metals that readily accommodate movement of hydrogen atoms interstitially is the driving variable that produces the widely observed episodes of excess heat above the total of all input energy. 2) This deuterium atom flux has been most often achieved at high electrochemical current densities on highly deuterium-loaded palladium cathodes but is clearly possible in other experimental arrangements in which the metal is interfacing gaseous deuterium, as in an electrical glow discharge. 3) Since the excess heat episodes must be producing the product(s) of some nuclear fusion reaction(s) screening of options may be easier with measurement of those ``ashes'' than the observance of the excess heat. 4) All but a few of the exothermic fusion reactions known among the first 5 elements produce He-4. Hence helium-4 appearance in an experiment may be the most efficient indicator of some fusion reaction without commitment on which reaction is occurring. This set of hypotheses led me to produce a series of sealed tubes of wire electrodes of metals known to absorb hydrogen and operate them for 100 days at the 1 watt power level using deuterium gas pressures of ~ 100 torr powered by 40 Khz AC power supplies. Observation of helium will be by measurement of helium optical emission lines through the glass envelope surrounding the discharge. The results of the first 18 months of this effort will be described.

Fast production of Bose-Einstein condensates of metastable helium

Science.gov (United States)

Bouton, Q.; Chang, R.; Hoendervanger, A. L.; Nogrette, F.; Aspect, A.; Westbrook, C. I.; Clément, D.

2015-06-01

We report on the Bose-Einstein condensation of metastable 4He atoms using a hybrid approach, consisting of a magnetic quadrupole and an optical dipole trap. In our setup we cross the phase transition with 2 ×106 atoms, and we obtain pure condensates of 5 ×105 atoms in the optical trap. This approach to cooling 4He provides enhanced cycle stability, large optical access to the atoms and results in the production of a condensate every 6 s—a factor 2 faster than the state of the art. This speed-up will significantly reduce the data acquisition time needed for the measurement of many particle correlations, made possible by the ability of metastable helium atoms to be detected individually.

Coupling the modular helium reactor to hydrogen production processes

International Nuclear Information System (INIS)

Richards, M.B.; Shenoy, A.S.; Schultz, K.R.

2004-01-01

Steam reforming of natural gas (methane) currently produces the bulk of hydrogen gas used in the world today. Because this process depletes natural gas resources and generates the greenhouse gas carbon dioxide as a by-product, there is a growing interest in using process heat and/or electricity generated by nuclear reactors to generate hydrogen by splitting water. Process heat from a high temperature nuclear reactor can be used directly to drive a set of chemical reactions, with the net result of splitting water into hydrogen and oxygen. For example, process heat at temperatures in the range 850 deg C to 950 deg C can drive the sulphur-iodine (S-I) thermochemical process to produce hydrogen with high efficiency. The S-I process produces highly pure hydrogen and oxygen, with formation, decomposition, regeneration, and recycle of the intermediate chemical reagents. Electricity can also 1)e used directly to split water, using conventional, low-temperature electrolysis (LTE). Hydrogen can also be produced with hybrid processes that use both process heat and electricity to generate hydrogen. An example of a hybrid process is high-temperature electrolysis (HTE), in which process heat is used to generate steam, which is then supplied to an electrolyzer to generate hydrogen. This process is of interest because the efficiency of electrolysis increases with temperature. Because of its high temperature capability, advanced stage of development relative to other high-temperature reactor concepts, and passive-safety features, the modular helium reactor (MHR) is well suited for producing hydrogen using nuclear energy. In this paper we investigate the coupling of the MHR to the S-I process, LTE, and HTE. These concepts are referred to as the H2-MHR. (author)

Comment on theories for helium-assisted void nucleation

International Nuclear Information System (INIS)

Russell, K.C.

1976-01-01

Voids form by agglomeration of irradiation-induced vacancies which remain after preferential absorption of self interstitials at dislocation lines. Helium which is formed by (n,α) transmutations and, in simulation studies, may be ion-implanted, often plays an important, but puzzling role. In some materials, very few voids form in the absence of helium, even after intense irradiation. In many other materials , voids form readily under a variety of irradiation conditions, even in the absence of helium. Why some materials require helium - typically in the 10 -6 apa (atom per atom) range - and others do not, and the reason for that particular level are by no means clear. The physics of void nucleation, particularly the role of helium, have been the subject of several theoretical papers. This note presents a critique of these theories, and then briefly outlines a new analysis which is not subject to their limitations. (Auth.)

Tritium Decay Helium-3 Effects in Tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Merrill, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-06-01

A critical challenge for long-term operation of ITER and beyond to a Demonstration reactor (DEMO) and future fusion reactor will be the development of plasma-facing components (PFCs) that demonstrate erosion resistance to steady-state/transient heat fluxes and intense neutral/ion particle fluxes under the extreme fusion nuclear environment, while at the same time minimizing in-vessel tritium inventories and permeation fluxes into the PFC’s coolant. Tritium will diffuse in bulk tungsten at elevated temperatures, and can be trapped in radiation-induced trap site (up to 1 at. % T/W) in tungsten [1,2]. Tritium decay into helium-3 may also play a major role in microstructural evolution (e.g. helium embrittlement) in tungsten due to relatively low helium-4 production (e.g. He/dpa ratio of 0.4-0.7 appm [3]) in tungsten. Tritium-decay helium-3 effect on tungsten is hardly understood, and its database is very limited. Two tungsten samples (99.99 at. % purity from A.L.M.T. Co., Japan) were exposed to high flux (ion flux of 1.0x1022 m-2s-1 and ion fluence of 1.0x1026 m-2) 0.5%T2/D2 plasma at two different temperatures (200, and 500°C) in Tritium Plasma Experiment (TPE) at Idaho National Laboratory. Tritium implanted samples were stored at ambient temperature in air for more than 3 years to investigate tritium decay helium-3 effect in tungsten. The tritium distributions on plasma-exposed was monitored by a tritium imaging plate technique during storage period [4]. Thermal desorption spectroscopy was performed with a ramp rate of 10°C/min up to 900°C to outgas residual deuterium and tritium but keep helium-3 in tungsten. These helium-3 implanted samples were exposed to deuterium plasma in TPE to investigate helium-3 effect on deuterium behavior in tungsten. The results show that tritium surface concentration in 200°C sample decreased to 30 %, but tritium surface concentration in 500°C sample did not alter over the 3 years storage period, indicating possible tritium

Review of Membranes for Helium Separation and Purification

Directory of Open Access Journals (Sweden)

Colin A. Scholes

2017-02-01

Full Text Available Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

Effect of helium on swelling and microstructural evolution in ion-irradiated V-15Cr-5Ti alloy

International Nuclear Information System (INIS)

Loomis, B.A.; Kestel, B.J.; Gerber, S.B.; Ayrault, G.

1986-03-01

An investigation was made on the effects of implanted helium on the swelling and microstructural evolution that results from energetic single- and dual-ion irradiation of the V-15Cr-5Ti alloy. Single-ion irradiations were utilized for a simulated production of the irradiation damage that might be expected from neutron irradiation of the alloy in a reactor with a fast neutron energy spectrum (E > 0.1 MeV). Dual-ion irradiations were utilized for a simulated production of the simultaneous creation of helium atoms and irradiation damage in the alloy in the MFR environment. Experimental results are also presented on the radiation-induced segregation of the constituent atoms in the single- and dual-ion irradiated alloy

Fast helium production in interactions of 3.7 A GeV 24Mg with emulsion nuclei

International Nuclear Information System (INIS)

Jilany, M.A.

2004-01-01

We have studied the properties of the relativistic helium fragments emitted from the projectile in the interactions of 24 Mg ions accelerated at an energy of 3.7 A GeV with emulsion nuclei. The total, partial nuclear cross-sections and production rates of helium fragmentation channels in relativistic nucleus-nucleus collisions and their dependence on the mass and energy of the incident projectile nucleus are investigated. The yields of multiple helium projectile fragments disrupted from the interactions of 24 Mg projectile nuclei with hydrogen H, light CNO and heavy AgBr groups of target emulsion nuclei are discussed and they indicate that the breakup mechanism of the projectile seems to be independent of the target mass. Limiting fragmentation behavior of fast-moving helium fragments is observed in both the projectile and target nuclei. The multiplicity distributions of helium projectile fragments emitted in the interactions of 24 Mg projectile nuclei with the different target nuclei of the emulsion are well described by the KNO scaling presentation. The mean multiplicities of the different charged secondary particles, normally defined shower, grey and black (left angle n s right angle, left angle n g right angle and left angle n b right angle) emitted in the interactions of 3.7 A GeV 24 Mg with the different groups of emulsion nuclei at different ranges of projectile fragments are decreasing when the number of He fragments stripped from projectile increases. These values of left angle n i right angle (i=s, g, band h particles) in the events where the emission of fast helium fragments were accompanied by heavy fragments having Z≥3 seem to be constant as the He multiplicity increases, and exhibit a behavior independent of the He multiplicity. (orig.)

Evolution of helium rich stars with hydrogen burning

International Nuclear Information System (INIS)

Roeser, M.

1975-08-01

Evolutionary tracks of stars with an initial chemical composition X = 0.100, Y = 0.8790, Z = 0.021 are calculated for masses of 0.35 M(sun), 0.66 M(sun), 1.00 M(sun), 2.00 M(sun), and 5.00 M(sun) and with X = 0.302, Y = 0.677, Z = 0.021 for masses of 1.00 M(sun), 3.00 M(sun), and 5.00 M(sun). The evolution is followed from hydrogen burning to helium burning and to carbon burning when the occasion arises. The data of evolution are presented and compared with normal Population I-stars. The helium rich stars show higher effective temperatures, much higher luminosities and therefore shorter time scales. They are situated in regions of the HR-diagram where observed helium stars are found. (orig.) [de

Metabolic activity in the insular cortex and hypothalamus predicts hot flashes: an FDG-PET study.

Science.gov (United States)

Joffe, Hadine; Deckersbach, Thilo; Lin, Nancy U; Makris, Nikos; Skaar, Todd C; Rauch, Scott L; Dougherty, Darin D; Hall, Janet E

2012-09-01

Hot flashes are a common side effect of adjuvant endocrine therapies (AET; leuprolide, tamoxifen, aromatase inhibitors) that reduce quality of life and treatment adherence in breast cancer patients. Because hot flashes affect only some women, preexisting neurobiological traits might predispose to their development. Previous studies have implicated the insula during the perception of hot flashes and the hypothalamus in thermoregulatory dysfunction. The aim of the study was to understand whether neurobiological factors predict hot flashes. [18F]-Fluorodeoxyglucose (FDG) positron emission tomography (PET) brain scans coregistered with structural magnetic resonance imaging were used to determine whether metabolic activity in the insula and hypothalamic thermoregulatory and estrogen-feedback regions measured before and in response to AET predict hot flashes. Findings were correlated with CYP2D6 genotype because of CYP2D6 polymorphism associations with tamoxifen-induced hot flashes. We measured regional cerebral metabolic rate of glucose uptake (rCMRglu) in the insula and hypothalamus on FDG-PET. Of 18 women without hot flashes who began AET, new-onset hot flashes were reported by 10 (55.6%) and were detected objectively in nine (50%) participants. Prior to the use of all AET, rCMRglu in the insula (P ≤ 0.01) and hypothalamic thermoregulatory (P = 0.045) and estrogen-feedback (P = 0.007) regions was lower in women who reported developing hot flashes. In response to AET, rCMRglu was further reduced in the insula in women developing hot flashes (P ≤ 0.02). Insular and hypothalamic rCMRglu levels were lower in intermediate than extensive CYP2D6 metabolizers. Trait neurobiological characteristics predict hot flashes. Genetic variability in CYP2D6 may underlie the neurobiological predisposition to hot flashes induced by AET.

Gone in a Flash: Manipulation of Audiovisual Temporal Integration Using Transcranial Magnetic Stimulation

Directory of Open Access Journals (Sweden)

Roy eHamilton

2013-09-01

Full Text Available While converging evidence implicates the right inferior parietal lobule in audiovisual integration, its role has not been fully elucidated by direct manipulation of cortical activity. Replicating and extending an experiment initially reported by Kamke, Vieth, Cottrell, and Mattingley (2012, we employed the sound-induced flash illusion, in which a single visual flash, when accompanied by two auditory tones, is misperceived as multiple flashes (Wilson, 1987; Shams, et al., 2000. Slow repetitive (1Hz TMS administered to the right angular gyrus, but not the right supramarginal gyrus, induced a transient decrease in the Peak Perceived Flashes (PPF, reflecting reduced susceptibility to the illusion. This finding independently confirms that perturbation of networks involved in multisensory integration can result in a more veridical representation of asynchronous auditory and visual events and that cross-modal integration is an active process in which the objective is the identification of a meaningful constellation of inputs, at times at the expense of accuracy.

Phototoxic effects of commercial photographic flash lamp on rat eyes.

Science.gov (United States)

Inoue, Makoto; Shinoda, Kei; Ohde, Hisao; Tezuka, Keiji; Hida, Tetsuo

2006-11-01

To determine whether exposure of the cornea and retina of rats to flashes from a commercial photographic flash lamp is phototoxic. Sprague-Dawley rats were exposed to 10, 100, or 1,000 flashes of the OPTICAM 16M photographic flash lamp (Fujikoeki, Japan) placed 0.1, 1, or 3 m from the eyes. Corneal damage was assessed by a fluorescein staining score, and the retinal damage by eletroretinography (ERG) and histology before and 24 h after exposure. Exposure of the eyes to 1,000 flashes at 0.1 m increased the fluorescein staining score significantly (P = 0.009, the Mann-Whitney test). Scanning electron microscopy (SEM) of the cornea showed a detachment of the epithelial cells from the surface after this exposure. The amplitude of the a-wave was decreased significantly by 23.0% (P = 0.026) of the amplitude before the exposure, and the b-wave by 19.7% (P = 0.0478) following 1,000 flashes at 0.1 m but not by the other exposures. TUNEL-positive cells were present in the outer nuclear layer only after the extreme exposure, but no significant decrease in retinal thickness was seen under any condition. The fluorescein staining score and ERGs recovered to control levels within 1 week. Light exposure to a photographic flash lamp does not induce damage to the cornea and retina except when they are exposed to 1,000 flashes at 0.1 m.

Laser-induced production of large carbon-based toroids

International Nuclear Information System (INIS)

Lyn, M. Elizabeth; He Jibao; Koplitz, Brent

2005-01-01

We report on the production of large carbon-based toroids (CBTs) from fullerenes. The process involves two-step laser irradiation of a mixed fullerene target (76% C 60 , 22% C 70 ). Transmission electron microscopy (TEM) clearly identifies toroidal-shaped structures as well as Q-shaped constructs. The typical diameters of the CBTs are ∼0.2-0.3 μm with tubular diameters of ∼50-100 nm, but toroids as wide as 0.5 μm are observed making them nanostructures on the verge of being microstructures

Pro Android Flash

CERN Document Server

Chin, Stephen; Campesato, Oswald

2011-01-01

Did you know you can take your Flash skills beyond the browser, allowing you to make apps for Android, iOS and the BlackBerry Tablet OS? Build dynamic apps today starting with the easy-to-use Android smartphones and tablets. Then, take your app to other platforms without writing native code. Pro Android Flash is the definitive guide to building Flash and other rich Internet applications (RIAs) on the Android platform. It covers the most popular RIA frameworks for Android developers - Flash and Flex - and shows how to build rich, immersive user experiences on both Android smartphones and tablet

Calculation of displacement and helium production at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF) irradiation facility

International Nuclear Information System (INIS)

Wechsler, M.S.; Davidson, D.R.; Greenwood, L.R.; Sommer, W.F.

1984-01-01

CT: Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF). The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 20 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

Flash X-ray

International Nuclear Information System (INIS)

Sato, Eiichi

2003-01-01

Generation of quasi-monochromatic X-ray by production of weakly ionized line plasma (flash X-ray), high-speed imaging by the X-ray and high-contrast imaging by the characteristic X-ray absorption are described. The equipment for the X-ray is consisted from the high-voltage power supply and condenser, turbo molecular pump, and plasma X-ray tube. The tube has a long linear anticathode to produce the line plasma and flash X-ray at 20 kA current at maximum. X-ray spectrum is measured by the imaging plate equipped in the computed radiography system after diffracted by a LiF single crystal bender. Cu anticathode generates sharp peaks of K X-ray series. The tissue images are presented for vertebra, rabbit ear and heart, and dog heart by X-ray fluoroscopy with Ce anticathode. Generation of K-orbit characteristic X-ray with extremely low bremsstrahung is to be attempted for medical use. (N.I.)

High-temperature helium embrittlement (T>=0,45Tsub(M)) of metals

International Nuclear Information System (INIS)

Batfalsky, P.

1984-06-01

High temperature helium embrittlement, swelling and irradiation creep are the main technical problem of fusion reactor materials. The expected helium production will be very high. The helium produced by (n,α)-processes precipitates into helium bubbles because its solubility in solid metals is very low. Under continuous helium production at high temperature and stress the helium bubbles grow and lead to intergranular early failure. Solution annealed foil specimens of austenitic stainless steel AISI 316 were implanted with α-particles: 1. during creep tests at 1023 K (''in-beam'' test) 2. before the creep tests at high temperature (1023 K). The creep tests have been performed within large ranges of test parameter, e.g. applied stress, temperature, helium implantation rate and helium concentration. After the creep tests the microstructure was investigated using scanning (SEM) and transmission (TEM) electron microscopy. All the helium implanted specimens showed high temperature helium embrittlement, i.e. reduction of rupture time tsub(R) and ductility epsilonsub(R) and evidence of intergranular brittle fracture. The ''in-beam'' creep tests showed greater reduction of rupture time tsub(R) and ductility than the preimplanted creep tests. The comparison of this experimentally obtained data with various theoretical models of high temperature helium embrittlement showed that within the investigated parameter ranges the mechanism controlling the life time of the samples is probably the gas driven stable growth of the helium bubbles within the grain boundaries. (orig.)

Flash!

Science.gov (United States)

Schilling, Govert

2002-04-01

About three times a day our sky flashes with a powerful pulse of gamma ray bursts (GRB), invisible to human eyes but not to astronomers' instruments. The sources of this intense radiation are likely to be emitting, within the span of seconds or minutes, more energy than the sun will in its entire 10 billion years of life. Where these bursts originate, and how they come to have such incredible energies, is a mystery scientists have been trying to solve for three decades. The phenomenon has resisted study -- the flashes come from random directions in space and vanish without trace -- until very recently. In what could be called a cinematic conflation of Flash Gordon and The Hunt for Red October, Govert Schilling's Flash!: The Hunt for the Biggest Explosions in the Universe describes the exciting and ever-changing field of GRB research. Based on interviews with leading scientists, Flash! provides an insider's account of the scientific challenges involved in unravelling the enigmatic nature of GRBs. A science writer who has followed the drama from the very start, Schilling describes the ambition and jealousy, collegiality and competition, triumph and tragedy, that exists among those who have embarked on this recherche. Govert Schilling is a Dutch science writer and astronomy publicist. He is a contributing editor of Sky and Telescope magazine, and regularly writes for the news sections of Science and New Scientist. Schilling is the astronomy writer for de Volkskrant, one of the largest national daily newspapers in The Netherlands, and frequently talks about the Universe on Dutch radio broadcasts. He is the author of more than twenty popular astronomy books, and hundreds of newspaper and magazine articles on astronomy.

Limitations of superfluid helium droplets as host system revealed by electronic spectroscopy of embedded molecules

Energy Technology Data Exchange (ETDEWEB)

Premke, Tobias

2016-02-19

Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the

A standing posture is associated with increased susceptibility to the sound-induced flash illusion in fall-prone older adults.

Science.gov (United States)

Stapleton, John; Setti, Annalisa; Doheny, Emer P; Kenny, Rose Anne; Newell, Fiona N

2014-02-01

Recent research has provided evidence suggesting a link between inefficient processing of multisensory information and incidence of falling in older adults. Specifically, Setti et al. (Exp Brain Res 209:375-384, 2011) reported that older adults with a history of falling were more susceptible than their healthy, age-matched counterparts to the sound-induced flash illusion. Here, we investigated whether balance control in fall-prone older adults was directly associated with multisensory integration by testing susceptibility to the illusion under two postural conditions: sitting and standing. Whilst standing, fall-prone older adults had a greater body sway than the age-matched healthy older adults and their body sway increased when presented with the audio-visual illusory but not the audio-visual congruent conditions. We also found an increase in susceptibility to the sound-induced flash illusion during standing relative to sitting for fall-prone older adults only. Importantly, no performance differences were found across groups in either the unisensory or non-illusory multisensory conditions across the two postures. These results suggest an important link between multisensory integration and balance control in older adults and have important implications for understanding why some older adults are prone to falling.

Modeling Secondary Neutral Helium in the Heliosphere

International Nuclear Information System (INIS)

Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

2016-01-01

An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

Strange matter and Big Bang helium synthesis

International Nuclear Information System (INIS)

Madsen, J.; Riisager, K.

1985-01-01

Stable strange quark matter produced in the QCD phase transition in the early universe will trap neutrons and repel protons, thus reducing primordial helium production, Ysub(p). For reasonable values of Ysub(p), the radius of strange droplets must exceed 10 -6 cm if strange matter shall solve the dark-matter problem without spoiling Big Bang helium synthesis. (orig.)

Professional Flash Lite Mobile Development

CERN Document Server

Anderson, J G

2010-01-01

Discover how to create Flash Lite mobile apps from the ground up. Adobe Flash is an ideal choice for developing rich interactive content for "Flash-enabled" mobile devices; and with this book, you'll learn how to create unique applications with Flash Lite. Through a series of code samples and extensive example applications, you'll explore the core concepts, key features, and best practices of the Flash Lite player. Coverage reveals various ways to develop Flash mobile content, create applications with a cross-platform programming framework based on the Model, View and Controller conc

Search Engine Optimization for Flash Best Practices for Using Flash on the Web

CERN Document Server

Perkins, Todd

2009-01-01

Search Engine Optimization for Flash dispels the myth that Flash-based websites won't show up in a web search by demonstrating exactly what you can do to make your site fully searchable -- no matter how much Flash it contains. You'll learn best practices for using HTML, CSS and JavaScript, as well as SWFObject, for building sites with Flash that will stand tall in search rankings.

Irradiation damage in boron carbide: point defects, clusters and helium bubbles

International Nuclear Information System (INIS)

Stoto, T.; Zuppiroli, L.

1986-06-01

Boron carbide is a refractory hard and light material of interest in nuclear technology (fission and also fusion). Transmission electron microscopy was used to examine the properties of radiation induced damage. Firstly, the production of point defects and their clustering was studied in samples irradiated by 1 MeV electron in a high voltage electron microscope at selected temperatures from 12 K to 1000 K. Secondly, conventional transmission electron microscopy was used to understand the production of helium bubbles in neutron irradiated boron carbide and their role in the generation of microcracks. Finally, the interaction between point defects and bubbles was also examined

Some properties of solid helium and helium nanoclusters using the effective HFD-like interaction potential: Adsorption and desorption inside carbon nanotube

Science.gov (United States)

Abbaspour, M.; Akbarzadeh, H.; Banihashemi, S. Z.; Sotoudeh, A.

2018-02-01

We have calculated the zero equation of state of solid helium using a two-body Hartree-Fock dispersion (HFD)-like potential from molecular dynamics (MD) simulation. To take many-body forces into account, our simple and accurate empirical expression is used with the HFD-like potential without requiring an expensive three-body calculation. This potential model also includes the quantum effects for helium at low temperatures. The results indicate that our effective HFD-like potential improves the prediction of the classical two-body results to get better agreement with experiment than many other two-body and three-body potentials of helium reported in the literature. We have also simulated the adsorption and desorption processes of the (He)55, (He)147, (He)309, (He)561, and (He)923 icosahedral nanoclusters confined into the different armchair and zigzag CNTs from 0 to 50 K using our effective model. We have observed an interesting phenomenon at 0 K for helium. The nanoclusters adsorb to the inner CNT wall as a melting process. But, the heavier noble gas clusters (such as Ne and Xe) show the different behavior than the He clusters. They form a multilayered solid structure into the CNT at zero temperature and adsorb into the inner wall of the CNT at higher temperatures. Our results for He clusters show that the absolute value of the adsorption energy increases as the size of the nanocluster increases. The desorption process begins at a certain temperature and represents itself by a jump in the configurational energy values. We have also investigated the structural and dynamical properties of the confined helium nanoclusters during the adsorption and desorption processes at different temperatures.

Programmable System-on-Chip (PSoC) Embedded Readout Designs for Liquid Helium Level Sensors.

Science.gov (United States)

Parasakthi, C; Gireesan, K; Usha Rani, R; Sheela, O K; Janawadkar, M P

2014-08-01

This article reports the development of programmable system-on-chip (PSoC)-based embedded readout designs for liquid helium level sensors using resistive liquid vapor discriminators. The system has been built for the measurement of liquid helium level in a concave-bottomed, helmet-shaped, fiber-reinforced plastic cryostat for magnetoencephalography. This design incorporates three carbon resistors as cost-effective sensors, which are mounted at desired heights inside the cryostat and were used to infer the liquid helium level by measuring their temperature-dependent resistance. Localized electrical heating of the carbon resistors was used to discriminate whether the resistor is immersed in liquid helium or its vapor by exploiting the difference in the heat transfer rates in the two environments. This report describes a single PSoC chip for the design and development of a constant current source to drive the three carbon resistors, a multiplexer to route the sensor outputs to the analog-to-digital converter (ADC), a buffer to avoid loading of the sensors, an ADC for digitizing the data, and a display using liquid crystal display cum light-emitting diode modules. The level sensor readout designed with a single PSoC chip enables cost-effective and reliable measurement system design. © 2014 Society for Laboratory Automation and Screening.

Raman Spectroscopy of Carbon Dust Samples from NSTX

International Nuclear Information System (INIS)

Raitses, Y.; Skinner, C.H.; Jiang, F.; Duffy, T.S.

2008-01-01

The Raman spectrum of dust particles exposed to the NSTX plasma is different from the spectrum of unexposed particles scraped from an unused graphite tile. For the unexposed particles, the high energy G-mode peak (Raman shift ∼1580 cm -1 ) is much stronger than the defect-induced D-mode peak (Raman shift ∼1350 cm -1 ), a pattern that is consistent with Raman spectrum for commercial graphite materials. For dust particles exposed to the plasma, the ratio of G-mode to D-mode peaks is lower and becomes even less than 1. The Raman measurements indicate that the production of carbon dust particles in NSTX involves modifications of the physical and chemical structure of the original graphite material. These modifications are shown to be similar to those measured for carbon deposits from atmospheric pressure helium arc discharge with an ablating anode electrode made from a graphite tile material. We also demonstrate experimentally that heating to 2000-2700 K alone can not explain the observed structural modifications indicating that they must be due to higher temperatures needed for graphite vaporization, which is followed either by condensation or some plasma-induced processes leading to the formation of more disordered forms of carbon material than the original graphite.

Flashing subdiffusive ratchets in viscoelastic media

International Nuclear Information System (INIS)

Kharchenko, Vasyl; Goychuk, Igor

2012-01-01

We study subdiffusive ratchet transport in periodically and randomly flashing potentials. A central Brownian particle is elastically coupled to the surrounding auxiliary Brownian quasi-particles, which account for the influence of the viscoelastic environment. Similar to standard dynamical modeling of Brownian motion, the external force influences only the motion of the central particle, not affecting directly the environmental degrees of freedom. Just a handful of auxiliary Brownian particles suffices to model subdiffusion over many temporal decades. Time modulation of the potential violates the symmetry of thermal detailed balance and induces an anomalous subdiffusive current which exhibits a remarkably small dispersion at low temperatures, as well as a number of other surprising features such as saturation at low temperatures, and multiple inversions of the transport direction upon a change of the driving frequency in the non-adiabatic regime. It is shown that the subdiffusive current is finite at zero temperature for random flashing and can be finite for periodic flashing for a certain frequency window. Our study generalizes classical Brownian motors towards operating in sticky viscoelastic environments such as the cytosol of biological cells or dense polymer solutions. (paper)

Standard Guide for Simulation of Helium Effects in Irradiated Metals

CERN Document Server

American Society for Testing and Materials. Philadelphia

1996-01-01

1.1 This guide provides advice for conducting experiments to investigate the effects of helium on the properties of metals where the technique for introducing the helium differs in some way from the actual mechanism of introduction of helium in service. Simulation techniques considered for introducing helium shall include charged particle implantation, exposure to α-emitting radioisotopes, and tritium decay techniques. Procedures for the analysis of helium content and helium distribution within the specimen are also recommended. 1.2 Two other methods for introducing helium into irradiated materials are not covered in this guide. They are the enhancement of helium production in nickel-bearing alloys by spectral tailoring in mixed-spectrum fission reactors, and isotopic tailoring in both fast and mixed-spectrum fission reactors. These techniques are described in Refs (1-5). Dual ion beam techniques (6) for simultaneously implanting helium and generating displacement damage are also not included here. This lat...

Influence of chemisorption products of carbon dioxide and water vapour on radiolysis of tritium breeder

Energy Technology Data Exchange (ETDEWEB)

Zarins, Arturs, E-mail: arturs.zarins@lu.lv [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia); Kizane, Gunta; Supe, Arnis [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia); Knitter, Regina; Kolb, Matthias H.H. [Karlsruhe Institute of Technology, Institute for Applied Materials (IAM-WPT), 76021 Karlsruhe (Germany); Tiliks, Juris; Baumane, Larisa [University of Latvia, Institute of Chemical Physics, Kronvalda Boulevard 4, LV-1010 Riga (Latvia)

2014-10-15

Highlights: • Chemisorption products affect formation proceses of radiation-induced defects. • Radiolysis of chemisorption products increase amount of radiation-induced defects. • Irradiation atmosphere influence radiolysis of lithium orthosilicate pebbles. - Abstract: Lithium orthosilicate pebbles with 2.5 wt% excess of silica are the reference tritium breeding material for the European solid breeder test blanket modules. On the surface of the pebbles chemisorption products of carbon dioxide and water vapour (lithium carbonate and hydroxide) may accumulate during the fabrication process. In this study the influence of the chemisorption products on radiolysis of the pebbles was investigated. Using nanosized lithium orthosilicate powders, factors, which can influence the formation and radiolysis of the chemisorption products, were determined and described as well. The formation of radiation-induced defects and radiolysis products was studied with electron spin resonance and the method of chemical scavengers. It was found that the radiolysis of the chemisorption products on the surface of the pebbles can increase the concentration of radiation-induced defects and so could affect the tritium diffusion, retention and the released species.

The role of helium ion microscopy in the characterisation of complex three-dimensional nanostructures

International Nuclear Information System (INIS)

Rodenburg, C.; Liu, X.; Jepson, M.A.E.; Zhou, Z.; Rainforth, W.M.; Rodenburg, J.M.

2010-01-01

This work addresses two major issues relating to Helium Ion Microscopy (HeIM). First we show that HeIM is capable of solving the interpretation difficulties that arise when complex three-dimensional structures are imaged using traditional high lateral resolution techniques which are transmission based, such as scanning transmission electron microscopy (STEM). Secondly we use a nano-composite coating consisting of amorphous carbon embedded in chromium rich matrix to estimate the mean escape depth for amorphous carbon for secondary electrons generated by helium ion impact as a measure of HeIM depth resolution.

NAND flash memory technologies

CERN Document Server

Aritome, Seiichi

2016-01-01

This book discusses basic and advanced NAND flash memory technologies, including the principle of NAND flash, memory cell technologies, multi-bits cell technologies, scaling challenges of memory cell, reliability, and 3-dimensional cell as the future technology. Chapter 1 describes the background and early history of NAND flash. The basic device structures and operations are described in Chapter 2. Next, the author discusses the memory cell technologies focused on scaling in Chapter 3, and introduces the advanced operations for multi-level cells in Chapter 4. The physical limitations for scaling are examined in Chapter 5, and Chapter 6 describes the reliability of NAND flash memory. Chapter 7 examines 3-dimensional (3D) NAND flash memory cells and discusses the pros and cons in structure, process, operations, scalability, and performance. In Chapter 8, challenges of 3D NAND flash memory are dis ussed. Finally, in Chapter 9, the author summarizes and describes the prospect of technologies and market for the fu...

Mechanical compression tests of beryllium pebbles after neutron irradiation up to 3000 appm helium production

Energy Technology Data Exchange (ETDEWEB)

Chakin, V., E-mail: vladimir.chakin@kit.edu [Karlsruhe Institute of Technology, Institite for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rolli, R.; Moeslang, A. [Karlsruhe Institute of Technology, Institite for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Zmitko, M. [The European Joint Undertaking for ITER and the Development of Fusion Energy, c/Josep Pla, no. 2, Torres Diagonal Litoral, Edificio B3, 08019 Barcelona (Spain)

2015-04-15

Highlights: • Compression tests of highly neutron irradiated beryllium pebbles have been performed. • Irradiation hardening of beryllium pebbles decreases the steady-state strain-rates. • The steady-state strain-rates of irradiated beryllium pebbles exceed their swelling rates. - Abstract: Results: of mechanical compression tests of irradiated and non-irradiated beryllium pebbles with diameters of 1 and 2 mm are presented. The neutron irradiation was performed in the HFR in Petten, The Netherlands at 686–968 K up to 1890–2950 appm helium production. The irradiation at 686 and 753 K cause irradiation hardening due to the gas bubble formation in beryllium. The irradiation-induced hardening leads to decrease of steady-state strain-rates of irradiated beryllium pebbles compared to non-irradiated ones. In contrary, after irradiation at higher temperatures of 861 and 968 K, the steady-state strain-rates of the pebbles increase because annealing of irradiation defects and softening of the material take place. It was shown that the steady-state strain-rates of irradiated beryllium pebbles always exceed their swelling rates.

26Al production in explosive burning of hydrogen-helium layers

International Nuclear Information System (INIS)

Arnould, M.; Hillebrand, W.; Thielemann, F.K.

1978-08-01

There is now strong evidence for the presence of live 26 Al (t 1 / 2 approximately 7.2 x 10 5 y) in the early solar system just before the beginning of its condensation phase. It is shown that the passage of a supernova shock wave through the outer part of the helium zone of a massive star can lead to significant 26 Al production if some protons are present in such external layers. In fact, a ratio 26 Al/ 27 Al approximately is derived for a proton mass fraction of the order of 5x10 -3 to 5x10 -2 . The required protons may survive from a preshock incomplete hydrogen burning or may result from some mixing with outer hydrogen-rich layers. (orig.) [de

Obtention of thermoluminescent efficiencies by means of irradiation of TLD-100 dosemeters with proton beams helium and carbon

International Nuclear Information System (INIS)

Avila, O.; Rodriguez V, M.; Aviles, P.; Gamboa de Buen, I.; Buenfil, A.E.; Ruiz T, C.; Brandan, M.E.

2002-01-01

In this work, the advances of a serial of measurements of relative efficiency thermoluminescent of heavy charged particles (PCP) with respect to gamma radiation for TLD-100, dosemeters of LiF: Mg,Ti manufactured by the Harshaw-Bicron company are reported. The PCP are essentials in the implementation of dosimetry associated with medical applications. The measurements before gamma radiation were carrying out using the Vickrad irradiator of the National Institute of Nuclear Research at dose of 1.663 Gy. The measures which are reported about protons, helium and carbon were realized using the Pelletron accelerator of the Physics Institute of the UNAM. (Author)

Valorization of waste Date pits biomass for biodiesel production in presence of green carbon catalyst

International Nuclear Information System (INIS)

Abu-Jrai, Ahmad M.; Jamil, Farrukh; Al-Muhtaseb, Ala'a H.; Baawain, Mahad; Al-Haj, Lamya; Al-Hinai, Mohab; Al-Abri, Mohammed; Rafiq, Sikander

2017-01-01

Highlights: • Waste Date pits were utilized to produce green catalyst for biodiesel production. • The optimized yield of biodiesel was 91.6% at 65 °C and 9:1 methanol to oil ratio. • Catalyst activity decreases very less upon reusing it up to three runs. • Produced biodiesel possess competent fuel properties as per ASTM and EN standards. - Abstract: In this study, an efficient utilization of waste Date pits biomass for synthesizing green carbon catalyst as well as production of biodiesel were investigated. The green carbon catalyst was modified by KOH and characterized by XRD, SEM, EDX, TEM and BET. Taguchi method in Response Surface Methodology (RSM) was applied to study the effect of several process parameters such as reaction temperature, time, catalysts type and methanol to oil ratio, on the yield of the produced biodiesel. The optimized yield obtained was 91.6% when the process temperature was 65 °C, with catalyst type C3 (6 wt% KOH on carbon) within 1 h and with 9:1 methanol to oil ratio. The produced biodiesel was completely characterized in order to verify its quality, compared with the international standards. Fuel properties of the produced biodiesel were found to be a cetane number 60.31, density 881 kg/m"3, viscosity 4.24 mm"2/s, cloud point 3.9 °C, cold filter plugging point −0.62 °C, pour point −1.4 °C and flash point 141 °C, which lies within the limits specified by the international standards of ASTM and EN. Waste Date pits biomass can be a promising platform for the production of green carbon catalysts as well as biodiesel production.

Helium ion beam induced growth of hammerhead AFM probes

NARCIS (Netherlands)

Nanda, G.; Veldhoven, E. van; Maas, D.J.; Sadeghian Marnani, H.; Alkemade, P.F.A.

2015-01-01

The authors report the direct-write growth of hammerhead atomic force microscope (AFM) probes by He+ beam induced deposition of platinum-carbon. In order to grow a thin nanoneedle on top of a conventional AFM probe, the authors move a focused He+ beam during exposure to a PtC precursor gas. In the

Accreting white dwarf models for type I supernovae. I. Presupernova evolution and triggering mechanisms

International Nuclear Information System (INIS)

Nomoto, K.

1982-01-01

The evolution of carbon-oxygen white dwarfs accreting helium in binary systems has been investigated from the onset of accretion up to the point at which a thermonuclear explosion occurs as a plausible explosion model for a Type I supernova. Although the accreted material has been assumed to be helium, our results should also be applicable to the more general case of accretion of hydrogen-rich material, since hydrogen shell burning leads to the development of a helium zone. Several cases with different accretion rates of helium and different initial masses of the white dwarf have been studied. The relationship between the conditions in the binary system and the triggering mechanism for the supernova explosion is discussed, especially for the cases with relatively slow accretion rate. It is found that the growth of a helium zone on the carbon-oxygen core leads to a supernova explosion which is triggered either by the off-center helium detonation for slow and intermediate accretion rates, or by the carbon deflagration for slow and rapid accretion rates. Both helium detonation and carbon deflagration are possible for the case for the slow accretion since, in this case, the initial mass of the white dwarf is an important parameter for determining the mode of ignition. Finally, various modes of building up the helium zone on the white dwarf, namely, direct transfer of helium from the companion star and the various types and strength of the hydrogen shell flashes are discussed in some detail

Flash grundkursus

DEFF Research Database (Denmark)

Jensen, Henrik

2008-01-01

Flash er et programmeringssprog  og kan som sådant ikke noget i sig selv. Kursets mål er, at give den studerende et grundlæggende kendskab til Flash, så det kan bruges til præsentationer på skærm og til produktion af hjemmesider. På kurset arbejdes der med billede, grafik, lyd, video og interakti...

Realization of mechanical rotation in superfluid helium

Science.gov (United States)

Gordon, E. B.; Kulish, M. I.; Karabulin, A. V.; Matyushenko, V. I.; Dyatlova, E. V.; Gordienko, A. S.; Stepanov, M. E.

2017-09-01

The possibility of using miniaturized low-power electric motors submerged in superfluid helium for organization of rotation inside a cryostat has been investigated. It has been revealed that many of commercial micromotors can operate in liquid helium consuming low power. Turret with 5 sample holders, assembled on the base of stepper motor, has been successfully tested in experiments on the nanowire production in quantized vortices of superfluid helium. Application of the stepper motor made it possible in a single experiment to study the effect of various experimental parameters on the yield and quality of the nanowires. The promises for continuous fast rotation of the bath filled by superfluid helium by using high-speed brushless micromotor were outlined and tested. Being realized, this approach will open new possibility to study the guest particles interaction with the array of parallel linear vortices in He II.

Mutational analysis of FLASH and PTPN13 genes in colorectal carcinomas.

Science.gov (United States)

Jeong, Eun Goo; Lee, Sung Hak; Yoo, Nam Jin; Lee, Sug Hyung

2008-01-01

The Fas-Fas ligand system is considered a major pathway for induction of apoptosis in cells and tissues. FLASH was identified as a pro-apoptotic protein that transmits apoptosis signal during Fas-mediated apoptosis. PTPN13 interacts with Fas and functions as both suppressor and inducer of Fas-mediated apoptosis. There are polyadenine tracts in both FLASH (A8 and A9 in exon 8) and PTPN13 (A8 in exon 7) genes that could be frameshift mutation targets in colorectal carcinomas. Because genes encoding proteins in Fas-mediated apoptosis frequently harbor somatic mutations in cancers, we explored the possibility as to whether mutations of FLASH and PTPN13 are a feature of colorectal carcinomas. We analysed human FLASH in exon 8 and PTPN13 in exon 7 for the detection of somatic mutations in 103 colorectal carcinomas by a polymerase chain reaction (PCR)- based single-strand conformation polymorphism (SSCP). We detected two mutations in FLASH gene, but none in PTPN13 gene. However, the two mutations were not frameshift (deletion or insertion) mutations in the polyadenine tracts of FLASH. The two mutations consisted of a deletion mutation (c.3734-3737delAGAA) and a missense mutation (c.3703A>C). These data indicate that frameshift mutation in the polyadenine tracts in both FLASH and PTPN13 genes is rare in colorectal carcinomas. Also, the data suggest that both FLASH and PTPN13 mutations in the polyadenine tracts may not have a crucial role in the pathogenesis of colorectal carcinomas.

The Blue Hook Populations of Massive Globular Clusters

Science.gov (United States)

Brown, Thomas

2006-07-01

Blue hook stars are a class of hot { 35,000 K} subluminous horizontal branch stars that have been recently discovered using HST ultraviolet images of the globular clusters omega Cen and NGC 2808. These stars occupy a region of the HR diagram that is unexplained by canonical stellar evolution theory. Using new theoretical evolutionary and atmospheric models, we have shown that the blue hook stars are very likely the progeny of stars that undergo extensive internal mixing during a late helium core flash on the white dwarf cooling curve. This "flash mixing" produces an enormous enhancement of the surface helium and carbon abundances, which suppresses the flux in the far ultraviolet. Although flash mixing is more likely to occur in stars that are born with high helium abundances, a high helium abundance, by itself, does not explain the presence of a blue hook population - flash mixing of the envelope is required. We propose ACS ultraviolet {SBC/F150LP and HRC/F250W} observations of the five additional globular clusters for which the presence of blue hook stars is suspected from longer wavelength observations. Like omega Cen and NGC 2808, these five targets are also among the most massive globular clusters, because less massive clusters show no evidence for blue hook stars. Because our targets span 1.5 dex in metallicity, we will be able to test our prediction that flash-mixing should be less drastic in metal-rich blue hook stars. In addition, our observations will test the hypothesis that blue hook stars only form in globular clusters massive enough to retain the helium-enriched ejecta from the first stellar generation. If this hypothesis is correct, then our observations will yield important constraints on the chemical evolution and early formation history in globular clusters, as well as the role of helium self-enrichment in producing blue horizontal branch morphologies and multiple main sequence turnoffs. Finally, our observations will provide new insight into the

USE OF THE MODULAR HELIUM REACTOR FOR HYDROGEN PRODUCTION

International Nuclear Information System (INIS)

SCHULTZ, K.R.

2003-01-01

OAK-B135 A significant ''Hydrogen Economy'' is predicted that will reduce our dependence on petroleum imports and reduce pollution and greenhouse gas emissions. Hydrogen is an environmentally attractive fuel that has the potential to displace fossil fuels, but contemporary hydrogen production is primarily based on fossil fuels. The author has recently completed a three-year project for the US Department of Energy (DOE) whose objective was to ''define an economically feasible concept for production of hydrogen, using an advanced high-temperature nuclear reactor as the energy source''. Thermochemical water-slitting, a chemical process that accomplishes the decomposition of water into hydrogen and oxygen, met this objective. The goal of the first phase of this study was to evaluate thermochemical processes which offer the potential for efficient, cost-effective, large-scale production of hydrogen, and to select one for further detailed consideration. They selected the Sulfur-Iodine cycle. In the second phase, they reviewed all the basic reactor types for suitability to provide the high temperature heat needed by the selected thermochemical water splitting cycle and chose the helium gas-cooled reactor. In the third phase they designed the chemical flowsheet for the thermochemical process and estimated the efficiency and cost of the process and the projected cost of producing hydrogen. These results are summarized in this report

Intense heavy ion beam-induced effects in carbon-based stripper foils

Energy Technology Data Exchange (ETDEWEB)

Kupka, Katharina

2016-08-15

-ray scattering (SAXS) were used. The changes of physical properties, in particular the electrical resistivity, thermal conductivity and stiffness of the foils were studied by in-situ 4-point probe, laser flash analysis and atomic force microscopy, respectively. A technique for measuring temperature of very thin, semitransparent and free-standing stripper foils during irradiation by means of an infrared (IR) camera was developed and applied. The experimental investigations were complemented by molecular dynamics simulations of amorphous carbon exposed to different swift heavy ions. The simulations provide information on the structural changes in the tracks at atomic scale. Virtual amorphous carbon cells were created by simulating liquid quenching and plasma deposition, yielding cells with different degrees of clustering of sp{sup 2} and sp{sup 3} bonding. The impacts of swift heavy ions were modeled by an instantaneous energy deposition deduced from inelastic thermal spike model calculations. Results of experiments and simulations provide evidence for the beam-induced transformation of amorphous carbon to a defected graphitic structure and for clustering of sp{sup 2} and sp{sup 3} bonds. These structural changes result in severe property changes. The electrical and thermal properties of amorphous carbon seem to improve during beam exposure, but the mechanical properties degrade severely. The beam conditions have a strong influence on the evolution of induced structure and property changes. A better understanding of the response of (amorphous) carbon stripper foils to swift heavy ion beams as revealed by dedicated irradiation and characterization experiments performed within this thesis, provides criteria for material requirements for future stripper foils used in high-power heavy ion accelerators such as FAIR.

Intense heavy ion beam-induced effects in carbon-based stripper foils

International Nuclear Information System (INIS)

Kupka, Katharina

2016-08-01

-ray scattering (SAXS) were used. The changes of physical properties, in particular the electrical resistivity, thermal conductivity and stiffness of the foils were studied by in-situ 4-point probe, laser flash analysis and atomic force microscopy, respectively. A technique for measuring temperature of very thin, semitransparent and free-standing stripper foils during irradiation by means of an infrared (IR) camera was developed and applied. The experimental investigations were complemented by molecular dynamics simulations of amorphous carbon exposed to different swift heavy ions. The simulations provide information on the structural changes in the tracks at atomic scale. Virtual amorphous carbon cells were created by simulating liquid quenching and plasma deposition, yielding cells with different degrees of clustering of sp 2 and sp 3 bonding. The impacts of swift heavy ions were modeled by an instantaneous energy deposition deduced from inelastic thermal spike model calculations. Results of experiments and simulations provide evidence for the beam-induced transformation of amorphous carbon to a defected graphitic structure and for clustering of sp 2 and sp 3 bonds. These structural changes result in severe property changes. The electrical and thermal properties of amorphous carbon seem to improve during beam exposure, but the mechanical properties degrade severely. The beam conditions have a strong influence on the evolution of induced structure and property changes. A better understanding of the response of (amorphous) carbon stripper foils to swift heavy ion beams as revealed by dedicated irradiation and characterization experiments performed within this thesis, provides criteria for material requirements for future stripper foils used in high-power heavy ion accelerators such as FAIR.

Damage to UV-sensitive cells by short UV in photographic flashes

International Nuclear Information System (INIS)

Menezes, S.; Monteiro, C.

1996-01-01

Light emitted by electronic photographic flash units is shown to damage bacteria and human skin fibroblasts deficient in repair systems, with survival curves very similar to those produced by 254 nm short UV. The lesions induced by these flashes are as photorepairable by the photolyase enzyme as those induced by 254 nm UV and result in equivalent survival rates. Biological dosimetry performed with microorganisms highly sensitive to UV (Escherichia coli K12 AB2480, deficient in excision and recombinational-dependent repair systems and Bacillus subtilis UVSSP spores, deficient in excision and in a specific spore repair process) revealed that each 1 ms flash of light from the photographic unit used in this work contained the equivalent of 0.25 J m -2 of 254 nm UV, when measured at a distance of 7.0 cm. This dose of UV was found to be lethal to both repair-deficient E. coli bacteria and repair-deficient human skin fibroblasts obtained from xeroderma pigmentosum donors, as well as mutagenic in B/r wild-type and HCR-mutant bacteria. (Author)

Flash Infrared Thermography Contrast Data Analysis Technique

Science.gov (United States)

Koshti, Ajay

2014-01-01

This paper provides information on an IR Contrast technique that involves extracting normalized contrast versus time evolutions from the flash thermography inspection infrared video data. The analysis calculates thermal measurement features from the contrast evolution. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat-bottom holes in the subject material. The measurement features and the contrast simulation are used to evaluate flash thermography data in order to characterize delamination-like anomalies. The thermal measurement features relate to the anomaly characteristics. The contrast evolution simulation is matched to the measured contrast evolution over an anomaly to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat-bottom hole (EFBH) similar to that used as input to the simulation. A similar analysis, in terms of diameter and depth of an equivalent uniform gap (EUG) providing a best match with the measured contrast evolution, is also provided. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH/EUG diameter are compared to evaluate the anomaly. The information provided here is geared towards explaining the IR Contrast technique. Results from a limited amount of validation data on reinforced carbon-carbon (RCC) hardware are included in this paper.

Density wave oscillations of a boiling natural circulation loop induced by flashing

Energy Technology Data Exchange (ETDEWEB)

Furuya, Masahiro; Inada, Fumio; Yasuo, Akira [Central Research Institute of Electric Power Industry, Tokyo (Japan)

1995-09-01

Experiments are conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney due to flashing in the chimney at lower pressure. The test facility used in this experiment is designed to have non-dimensional values which are nearly equal to those of natural circulation BWR. Stability maps in reference to the heat flux, the inlet subcooling, the system pressure are presented. This instability is suggested to be density wave oscillations due to flashing in the chimney, and the differences from other phenomena such as flow pattern oscillations and geysering phenomena are discussed by investigating the dynamic characteristics, the oscillation period, and the transient flow pattern.

IBA studies of helium mobility in nuclear materials revisited

Energy Technology Data Exchange (ETDEWEB)

Trocellier, P., E-mail: patrick.trocellier@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Agarwal, S.; Miro, S. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Vaubaillon, S. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); CEA, INSTN, UEPTN, F-91191 Gif-sur-Yvette (France); Leprêtre, F.; Serruys, Y. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

2015-12-15

The aim of this paper is to point out and to discuss some features extracted from the study of helium migration in nuclear materials performed during the last fifteen years using ion beam analysis (IBA) measurements. The first part of this paper is devoted to a brief description of the two main IBA methods used, i.e. deuteron induced nuclear reaction for {sup 3}He depth profiling and high-energy heavy-ion induced elastic recoil detection analysis for {sup 4}He measurement. In the second part, we provide an overview of the different studies carried out on model nuclear waste matrices and model nuclear reactor structure materials in order to illustrate and discuss specific results in terms of key influence parameters in relation with thermal or radiation activated migration of helium. Finally, we show that among the key parameters we have investigated as able to influence the height of the helium migration barrier, the following can be considered as pertinent: the experimental conditions used to introduce helium (implanted ion energy and implantation fluence), the grain size of the matrix, the lattice cell volume, the Young's modulus, the ionicity degree of the chemical bond between the transition metal atom M and the non-metal atom X, and the width of the band gap.

Comparison of multilayered nanowire imaging by SEM and Helium Ion Microscopy

International Nuclear Information System (INIS)

Inkson, B J; Peng, Y; Jepson, M A E; Rodenburg, C; Liu, X

2010-01-01

The helium ion microscope (HeIM) is capable of probe sizes smaller than SEM and, with intrinsically small ion/sample interaction volumes, may therefore potentially offer higher spatial resolution secondary electron (SE) imaging of nanostructures. Here 55 nm diameter CoPt/Pt multilayered nanowires have been imaged by HeIM, SEM and TEM. It is found that there is an increased resolution of nanowire surface topography in HeIM SE images compared to SEM, however there is a reduction of materials contrast of the alternating Pt and CoPt layers. This can be attributed to the increased contribution of surface contamination layers to the ion-induced SE signal, and carbon is also observed to grow on the nanowires under prolonged HeIM scanning.

Learning Flash CS4 Professional

CERN Document Server

Shupe, Rich

2009-01-01

Learning Flash CS4 Professional offers beginners and intermediate Flash developers a unique introduction to the latest version of Adobe's powerful multimedia application. This easy-to-read book is loaded with full-color examples and hands-on tasks to help you master Flash CS4's new motion editor, integrated 3D system, and character control using the new inverse kinematics bones animation system. No previous Flash experience is necessary.

On the Induced Gravitational Collapse

Directory of Open Access Journals (Sweden)

M. Becerra Laura

2018-01-01

Full Text Available The induced gravitational collapse (IGC paradigm has been applied to explain the long gamma ray burst (GRB associated with type Ic supernova, and recently the Xray flashes (XRFs. The progenitor is a binary systems of a carbon-oxygen core (CO and a neutron star (NS. The CO core collapses and undergoes a supernova explosion which triggers the hypercritical accretion onto the NS companion (up to 10-2 M⊙s-1. For the binary driven hypernova (BdHNe, the binary system is enough bound, the NS reach its critical mass, and collapse to a black hole (BH with a GRB emission characterized by an isotropic energy Eiso > 1052 erg. Otherwise, for binary systems with larger binary separations, the hypercritical accretion onto the NS is not sufficient to induced its gravitational collapse, a X-ray flash is produced with Eiso < 1052 erg. We’re going to focus in identify the binary parameters that limits the BdHNe systems with the XRFs systems.

Cryogenic filter method produces super-pure helium and helium isotopes

Science.gov (United States)

Hildebrandt, A. F.

1964-01-01

Helium is purified when cooled in a low pressure environment until it becomes superfluid. The liquid helium is then filtered through iron oxide particles. Heating, cooling and filtering processes continue until the purified liquid helium is heated to a gas.

Impact of Glycerol as Carbon Source onto Specific Sugar and Inducer Uptake Rates and Inclusion Body Productivity in E. coli BL21(DE3

Directory of Open Access Journals (Sweden)

Julian Kopp

2017-12-01

Full Text Available The Gram-negative bacterium E. coli is the host of choice for a multitude of used recombinant proteins. Generally, cultivation is easy, media are cheap, and a high product titer can be obtained. However, harsh induction procedures using isopropyl β-d-1 thiogalactopyranoside as inducer are often referred to cause stress reactions, leading to a phenomenon known as “metabolic” or “product burden”. These high expressions of recombinant proteins mainly result in decreased growth rates and cell lysis at elevated induction times. Therefore, approaches tend to use “soft” or “tunable” induction with lactose and reduce the stress level of the production host. The usage of glucose as energy source in combination with lactose as induction reagent causes catabolite repression effects on lactose uptake kinetics and as a consequence reduced product titer. Glycerol—as an alternative carbon source—is already known to have positive impact on product formation when coupled with glucose and lactose in auto-induction systems, and has been referred to show no signs of repression when cultivated with lactose concomitantly. In recent research activities, the impact of different products on the lactose uptake using glucose as carbon source was highlighted, and a mechanistic model for glucose-lactose induction systems showed correlations between specific substrate uptake rate for glucose or glycerol (qs,C and the maximum specific lactose uptake rate (qs,lac,max. In this study, we investigated the mechanistic of glycerol uptake when using the inducer lactose. We were able to show that a product-producing strain has significantly higher inducer uptake rates when being compared to a non-producer strain. Additionally, it was shown that glycerol has beneficial effects on viability of cells and on productivity of the recombinant protein compared to glucose.

Flash photolysis of carbon dioxide in the far ultra-violet

International Nuclear Information System (INIS)

Barat, F.

1970-01-01

The flash photolysis of CO 2 (3 torr) in the far ultra-violet, down to the transparency limit of lithium fluoride, produces vibrationally excited CO in its Χ 1 Σ electronic ground state and an electronically excited oxygen atom O( 1 D). After photolysis, the changes in the concentration of vibrationally de-excited CO in the 0 to 200 μsec, time range are followed using absorption spectroscopy. These changes can be explained on the basis of three main competing reactions: CO(Χ 1 Σ, ν'' = 0) + O( 1 D) → CO 2 ( 1 Σ g + ), O( 1 D) + CO 2 → O( 3 P) + CO 2 and CO 3 , CO(X 1 Σ, ν'' = 1,2) + CO 2 → CO(Χ 1 Σ, ν'' = 0) + CO 2 . The values of the rate constants for these three reactions are determined by analog calculations. The effect of O( 1 D) scavenging or quenching gases on the oxidation reaction of CO by O( 1 D) is examined. A study of the flash photolysis of O 2 in the presence of CO in the far ultra-violet makes it possible to eliminate the hypothesis that CO 3 is involved in the reaction leading to the disappearance of CO after photolysis. (author) [fr

Flashing oscillation in pool water

International Nuclear Information System (INIS)

Takamasa, Tomoji; Kondo, Koichi; Hazuku, Tatsuya

1996-01-01

This paper presents an experimental study of high-pressure saturated water discharging into the pool water. The purpose of the experiment is to clarify the phenomena that occur in blow-down of high-pressure saturated water from the pressure vessel into the water-filled containment in the case of a wall-crack accident or a LOCA in an advanced reactor. The results revealed that a flashing oscillation (FO) occurs when high-pressure saturated water discharges into the pool water, under specified experimental settings. The range of the flashing oscillates between a point very close to and some distance from the vent hole. The pressures in the vent tube and pool water vary according to the flashing oscillation. The pressure oscillation and frequency of flashing position might be caused by the balancing action between the supply of saturated water, flashing at the control volume and its condensation on the steam-water interface. A linear analysis was conducted using a spherical flashing bubble model. The period of the flashing oscillation in the experiments can be explained by theoretical analysis

Calculated differential secondary-particle production cross sections after nonelastic neutron interactions with carbon and oxygen between 15 and 60 MeV

International Nuclear Information System (INIS)

Brenner, D.J.; Prael, R.E.

1989-01-01

Calculated values are given for double-differential (energy/angle) cross sections for the nonelastic production of hydrogen and helium isotopes and heavier-mass recoils, after the interaction of 15- to 60-MeV neutrons with carbon and oxygen. The data are calculated with an intranuclear cascade code, including alpha clustering and particle pickup, followed by a Fermi-breakup mechanism, incorporating decay via intermediate particle-unstable states. The predictions have been extensively tested against available experimental data in this energy/mass range. copyright 1989 Academic Press, Inc

Tritium decay helium-3 effects in tungsten

Directory of Open Access Journals (Sweden)

M. Shimada

2017-08-01

Full Text Available Tritium (T implanted by plasmas diffuses into bulk material, especially rapidly at elevated temperatures, and becomes trapped in neutron radiation-induced defects in materials that act as trapping sites for the tritium. The trapped tritium atoms will decay to produce helium-3 (3He atoms at a half-life of 12.3 years. 3He has a large cross section for absorbing thermal neutrons, which after absorbing a neutron produces hydrogen (H and tritium ions with a combined kinetic energy of 0.76 MeV through the 3He(n,HT nuclear reaction. The purpose of this paper is to quantify the 3He produced in tungsten by tritium decay compared to the neutron-induced helium-4 (4He produced in tungsten. This is important given the fact that helium in materials not only creates microstructural damage in the bulk of the material but alters surface morphology of the material effecting plasma-surface interaction process (e.g. material evolution, erosion and tritium behavior of plasma-facing component materials. Effects of tritium decay 3He in tungsten are investigated here with a simple model that predicts quantity of 3He produced in a fusion DEMO FW based on a neutron energy spectrum found in literature. This study reveals that: (1 helium-3 concentration was equilibrated to ∼6% of initial/trapped tritium concentration, (2 tritium concentration remained approximately constant (94% of initial tritium concentration, and (3 displacement damage from 3He(n,HT nuclear reaction became >1 dpa/year in DEMO FW.

Optimization of mass flow rate in RGTT200K coolant purification for Carbon Monoxide conversion process

International Nuclear Information System (INIS)

Sumijanto; Sriyono

2016-01-01

Carbon monoxide is a species that is difficult to be separated from the reactor coolant helium because it has a relatively small molecular size. So it needs a process of conversion from carbon monoxide to carbondioxide. The rate of conversion of carbon monoxide in the purification system is influenced by several parameters including concentration, temperature and mass flow rate. In this research, optimization of the mass flow rate in coolant purification of RGTT200K for carbon monoxide conversion process was done. Optimization is carried out by using software Super Pro Designer. The rate of reduction of reactant species, the growth rate between the species and the species products in the conversion reactions equilibrium were analyzed to derive the mass flow rate optimization of purification for carbon monoxide conversion process. The purpose of this study is to find the mass flow rate of purification for the preparation of the basic design of the RGTT200K coolant helium purification system. The analysis showed that the helium mass flow rate of 0.6 kg/second resulted in an un optimal conversion process. The optimal conversion process was reached at a mass flow rate of 1.2 kg/second. A flow rate of 3.6 kg/second – 12 kg/second resulted in an ineffective process. For supporting the basic design of the RGTT200K helium purification system, the mass flow rate for carbon monoxide conversion process is suggested to be 1.2 kg/second. (author)

Net energy benefits of carbon nanotube applications

International Nuclear Information System (INIS)

Zhai, Pei; Isaacs, Jacqueline A.; Eckelman, Matthew J.

2016-01-01

Highlights: • Life cycle net energy benefits are examined. • CNT-enabled and the conventional technologies are compared. • Flash memory with CNT switches show significant positive net energy benefit. • Lithium-ion batteries with MWCNT cathodes show positive net energy benefit. • Lithium-ion batteries with SWCNT anodes tend to exhibit negative net energy benefit. - Abstract: Implementation of carbon nanotubes (CNTs) in various applications can reduce material and energy requirements of products, resulting in energy savings. However, processes for the production of carbon nanotubes (CNTs) are energy-intensive and can require extensive purification. In this study, we investigate the net energy benefits of three CNT-enabled technologies: multi-walled CNT (MWCNT) reinforced cement used as highway construction material, single-walled CNT (SWCNT) flash memory switches used in cell phones and CNT anodes and cathodes used in lithium-ion batteries used in electric vehicles. We explore the avoided or additional energy requirement in the manufacturing and use phases and estimate the life cycle net energy benefits for each application. Additional scenario analysis and Monte Carlo simulation of parameter uncertainties resulted in probability distributions of net energy benefits, indicating that net energy benefits are dependent on the application with confidence intervals straddling the breakeven line in some cases. Analysis of simulation results reveals that SWCNT switch flash memory and MWCNT Li-ion battery cathodes have statistically significant positive net energy benefits (α = 0.05) and SWCNT Li-ion battery anodes tend to have negative net energy benefits, while positive results for MWCNT-reinforced cement were significant only under an efficient CNT production scenario and a lower confidence level (α = 0.1).

Modeling midwave infrared muzzle flash spectra from unsuppressed and flash-suppressed large caliber munitions

Science.gov (United States)

Steward, Bryan J.; Perram, Glen P.; Gross, Kevin C.

2012-07-01

Time-resolved infrared spectra of firings from a 152 mm howitzer were acquired over an 1800-6000 cm-1 spectral range using a Fourier-transform spectrometer. The instrument collected primarily at 32 cm-1 spectral and 100 Hz temporal resolutions. Munitions included unsuppressed and chemically flash suppressed propellants. Secondary combustion occurred with unsuppressed propellants resulting in flash emissions lasting ˜100 ms and dominated by H2O and CO2 spectral structure. Non-combusting plume emissions were one-tenth as intense and approached background levels within 20-40 ms. A low-dimensional phenomenological model was used to reduce the data to temperatures, soot absorbances, and column densities of H2O, CO2, CH4, and CO. The combusting plumes exhibit peak temperatures of ˜1400 K, areas of greater than 32 m2, low soot emissivity of ˜0.04, with nearly all the CO converted to CO2. The non-combusting plumes exhibit lower temperatures of ˜1000 K, areas of ˜5 m2, soot emissivity of greater than 0.38 and CO as the primary product. Maximum fit residual relative to peak intensity are 14% and 8.9% for combusting and non-combusting plumes, respectively. The model was generalized to account for turbulence-induced variations in the muzzle plumes. Distributions of temperature and concentration in 1-2 spatial regions demonstrate a reduction in maximum residuals by 40%. A two-region model of combusting plumes provides a plausible interpretation as a ˜1550 K, optically thick plume core and ˜2550 K, thin, surface-layer flame-front. Temperature rate of change was used to characterize timescales and energy release for plume emissions. Heat of combustion was estimated to be ˜5 MJ/kg.

Hot flashes and sleep in women.

Science.gov (United States)

Moe, Karen E

2004-12-01

Sleep disturbances during menopause are often attributed to nocturnal hot flashes and 'sweats' associated with changing hormone patterns. This paper is a comprehensive critical review of the research on the relationship between sleep disturbance and hot flashes in women. Numerous studies have found a relationship between self-reported hot flashes and sleep complaints. However, hot flash studies using objective sleep assessment techniques such as polysomnography, actigraphy, or quantitative analysis of the sleep EEG are surprisingly scarce and have yielded somewhat mixed results. Much of this limited evidence suggests that hot flashes are associated with objectively identified sleep disruption in at least some women. At least some of the negative data may be due to methodological issues such as reliance upon problematic self-reports of nocturnal hot flashes and a lack of concurrent measures of hot flashes and sleep. The recent development of a reliable and non-intrusive method for objectively identifying hot flashes during the night should help address the need for substantial additional research in this area. Several areas of clinical relevance are described, including the effects of discontinuing combined hormone therapy (estrogen plus progesterone) or estrogen-only therapy, the possibility of hot flashes continuing for many years after menopause, and the link between hot flashes and depression.

MR colonography with fecal tagging: comparison between 2D turbo FLASH and 3D FLASH sequences

International Nuclear Information System (INIS)

Papanikolaou, Nickolas; Grammatikakis, John; Maris, Thomas; Prassopoulos, Panos; Gourtsoyiannis, Nicholas; Lauenstein, Thomas

2003-01-01

The objective of this study was to compare inversion recovery turbo 2D fast low-angle shot (FLASH) and 3D FLASH sequences for fecal-tagged MR colonography studies. Fifteen consecutive patients with indications for colonoscopy underwent MR colonography with fecal tagging. An inversion recovery turbo-FLASH sequence was applied and compared in terms of artifacts presence, efficiency for masking residual stool, and colonic wall conspicuity with a fat-saturated 3D FLASH sequence. Both sequences were acquired following administration of paramagnetic contrast agent. Contrast-to-noise ratio and relative contrast between colonic wall and lumen were calculated and compared for both sequences. Turbo 2D FLASH provided fewer artifacts, higher efficiency for masking the residual stool, and colonic wall conspicuity equivalent to 3D FLASH. An inversion time of 10 ms provided homogeneously low signal intensity of the colonic lumen. Contrast to noise between colonic wall and lumen was significantly higher in the 3D FLASH images, whereas differences in relative contrast were not statistically significant. An optimized inversion-recovery 2D turbo-FLASH sequence provides better fecal tagging results and should be added to the 3D FLASH sequence when designing dark-lumen MR colonography examination protocols. (orig.)

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI

Energy Technology Data Exchange (ETDEWEB)

Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-08-20

A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

Flash pyrolysis of linseed (Linum usitatissimum L.) for production of liquid fuels

Energy Technology Data Exchange (ETDEWEB)

Acikgoz, C. [Department of Chemical Technology, Bilecik Higher Vocational School, GueluembeCampus, Anadolu University, 11030 Bilecik (Turkey); Kockar, O.M. [Department of Chemical Engineering, Faculty of Engineering and Architecture, iki Eyluel Campus, Anadolu University, 26470 Eskisehir (Turkey)

2007-03-15

Flash pyrolysis experiments of linseed (Linum usitatissimum L.) were performed in a tubular transport reactor at atmospheric pressure under nitrogen atmosphere. The effects of pyrolysis temperature and particle size on the yields of products were investigated with the sweep gas flow rate of 100 cm{sup 3} min{sup -1}. The temperature of pyrolysis and particle size were varied in the ranges 400-700 C and 0.6 mm < D{sub p} < 1.25 mm, 1.25 mm < D{sub p} < 1.8 mm, D{sub p} > 1.8 mm, respectively. The maximum oil yield of 68.8% was obtained at a pyrolysis temperature of 550 C, and the particle size of D{sub p} > 1.8 mm. The char and liquid product were analyzed to determine their elemental composition and calorific value. In particular, the chemical composition of the oil was investigated using chromatographic and spectroscopic techniques ({sup 1}H NMR, IR, column chromatography and GC). The chemical characterization has shown that the oil obtained from linseed can be used as a renewable fuel and chemical feedstock. (author)

Helium cryogenics

CERN Document Server

Van Sciver, Steven W

2012-01-01

Twenty five years have elapsed since the original publication of Helium Cryogenics. During this time, a considerable amount of research and development involving helium fluids has been carried out culminating in several large-scale projects. Furthermore, the field has matured through these efforts so that there is now a broad engineering base to assist the development of future projects. Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspe...

Flash-Type Discrimination

Science.gov (United States)

Koshak, William J.

2010-01-01

This viewgraph presentation describes the significant progress made in the flash-type discrimination algorithm development. The contents include: 1) Highlights of Progress for GLM-R3 Flash-Type discrimination Algorithm Development; 2) Maximum Group Area (MGA) Data; 3) Retrieval Errors from Simulations; and 4) Preliminary Global-scale Retrieval.

Light charged particle production in fast neutron-induced reactions on carbon (En=40 to 75 MeV) (II). Tritons and alpha particles

International Nuclear Information System (INIS)

Dufauquez, C.; Slypen, I.; Benck, S.; Meulders, J.P.; Corcalciuc, V.

2000-01-01

Double-differential cross sections for fast neutron-induced triton and alpha-particle production on carbon are reported at six incident neutron energies between 40 and 75 MeV. Angular distributions were measured at laboratory angles between 20 deg. and 160 deg. . Energy-differential, angle-differential and total cross sections are also reported. Experimental cross sections are compared to existing experimental data and to theoretical model calculations

Helium ion beam induced electron emission from insulating silicon nitride films under charging conditions

Science.gov (United States)

Petrov, Yu. V.; Anikeva, A. E.; Vyvenko, O. F.

2018-06-01

Secondary electron emission from thin silicon nitride films of different thicknesses on silicon excited by helium ions with energies from 15 to 35 keV was investigated in the helium ion microscope. Secondary electron yield measured with Everhart-Thornley detector decreased with the irradiation time because of the charging of insulating films tending to zero or reaching a non-zero value for relatively thick or thin films, respectively. The finiteness of secondary electron yield value, which was found to be proportional to electronic energy losses of the helium ion in silicon substrate, can be explained by the electron emission excited from the substrate by the helium ions. The method of measurement of secondary electron energy distribution from insulators was suggested, and secondary electron energy distribution from silicon nitride was obtained.

Recent progress in the modelling of helium and tritium behaviour in irradiated beryllium pebbles

International Nuclear Information System (INIS)

Rabaglino, E.; Ronchi, C.; Cardella, A.

2003-01-01

One of the key issues of the European Helium Cooled Pebble Bed blanket is the behaviour under irradiation of beryllium pebbles, which have the function of neutron multiplier. An intense production of helium occurs in-pile, as well as a non negligible generation of tritium. Helium bubbles induce swelling and a high tritium inventory is a safety issue. Extensive studies for a better understanding, characterisation and modelling of the behaviour of helium and tritium in irradiated beryllium pebbles are being carried out, with the final aim to enable a reliable prediction of gas release and swelling in the full range of operating and accidental conditions of a Fusion Power Reactor. The general strategy consists in integrating studies on macroscopic phenomena (gas release) with the characterisation of corresponding microscopic diffusion phenomena (bubble kinetics) and the assessment of some fundamental diffusion parameter for the models (gas atomic diffusion coefficients). The present work gives a summary of the latest achievements in this context. By an inverse analysis of experimental out-of-pile gas release from weakly irradiated pebbles, coupled to the study of the characteristics of bubble population, it has been possible to assess the thermal diffusion coefficients of helium and tritium in and to improve and validate the classical model of gas precipitation into bubbles inside the grain. The improvement of the description of gas atomic diffusion and precipitation is the first step to enable a more reliable prediction of gas release

Carbon monoxide and carbon dioxide interaction with tantalum

International Nuclear Information System (INIS)

Belov, V.D.; Ustinov, Yu.K.; Komar, A.P.

1978-01-01

The adsorption of carbon monoxide and carbon dioxide on tantalum and the dissolution of these gases in the adsorbent at T >= 300 K have been studied. The flash-filament method (FFM) in a monopole mass-spectrometer and a field emission microscopy was used in the same apparatus. Carbon monoxide and carbon dioxide dissociate on the tantalum surface, carbon monoxide being desorbed in both cases during the flash. The desorption curves of CO reveal three different binding states: two of them (α and β' 1 ) for the adsorbed particles whereas the high temperature desorption state relates to the adsorbate dissolved in the metal. For the β' 1 state of CO the activation energy, the pre-exponential factor and the kinetic order in the kinetic equation of desorption have been estimated. They turned out to be E = 110 kcal/mol, C = 3 X 10 12 sec -1 , and γ = 1. The activation energy of diffusion for CO in tantalum and the energy of outgassing for the metal were found to be 9.4 and 49 kcal/mole, respectively. (Auth.)

Carbon monoxide and carbon dioxide interaction with tantalum

Energy Technology Data Exchange (ETDEWEB)

Belov, V D; USTINOV, YU K; KOMAR, A P [AN SSSR, LENINGRAD. FIZIKO-TEKHNICHESKIJ INST.

1978-03-01

The adsorption of carbon monoxide and carbon dioxide on tantalum and the dissolution of these gases in the adsorbent at T >= 300 K have been studied. The flash-filament method (FFM) in a monopole mass-spectrometer and a field emission microscopy was used in the same apparatus. Carbon monoxide and carbon dioxide dissociate on the tantalum surface, carbon monoxide being desorbed in both cases during the flash. The desorption curves of CO reveal three different binding states: two of them (..cap alpha.. and ..beta..'/sub 1/) for the adsorbed particles whereas the high temperature desorption state relates to the adsorbate dissolved in the metal. For the ..beta..'/sub 1/ state of CO the activation energy, the pre-exponential factor and the kinetic order in the kinetic equation of desorption have been estimated. They turned out to be E = 110 kcal/mol, C = 3 X 10/sup 12/ sec/sup -1/, and ..gamma.. = 1. The activation energy of diffusion for CO in tantalum and the energy of outgassing for the metal were found to be 9.4 and 49 kcal/mole, respectively.

Structural evolution of Eucalyptus tar pitch-based carbons during carbonization

International Nuclear Information System (INIS)

Prauchner, Marcos J.; Pasa, Vanya M.D.; Molhallem, Nelcy D.S.; Otani, Choyu; Otani, Satika; Pardini, Luiz C.

2005-01-01

Wood tar pitches are generated as by-products by the charcoal manufacturing industry. They have a macromolecular structure constituted mainly by phenolic, guaiacylic, and siringylic units common to lignin. Due to their characteristics, biopitches are been investigated as precursors of carbon materials such as carbon fibers, bioelectrodes and activated carbons. In the present work the structural evolution of Eucalyptus tar pitches under carbonization is investigated, which is important for the improvement of planning and control of pitch processing and end-product properties during carbon material production. The studies involve X-ray diffraction and infrared analyses, besides helium density, BET surface area and BJH pore volume measurements. The results showed that the conversion of pitch into carbon basically involves three steps: (1) Up to around 600 deg C the material has an highly disordered structure, being the release of aliphatic side chains and volatiles the main events taking place. (2) Between 600 deg C and 800 deg C, condensation of aromatic rings occurs to form bi-dimensional hexagonal networks so that micro- and mesoporosity are developed. The 800 deg C-coke is constituted by two phases: one highly disordered and another more crystalline. (3) Over 800 deg C, both phases are gradually ordered. As defects are gradually removed, surface area and porosity decrease, approaching zero for the 2100 deg C-coke

Electron cyclotron resonance hydrogen/helium plasma characterization and simulation of pumping in tokamaks

International Nuclear Information System (INIS)

Outten, C.A.

1992-01-01

Electron Cyclotron Resonance (ECR) plasmas have been employed to simulate the plasma conditions at the edge of a tokamak in order to investigate hydrogen/helium uptake in thin metal films. The process of microwave power absorption, important to characterizing the ECR plasma source, was investigated by measuring the electron density and temperature with a Langmuir probe and optical spectroscopy as a function of the magnetic field gradient and incident microwave power. A novel diagnostic, carbon resistance probe, provided a direct measure of the ion energy and fluence while measurements from a Langmuir probe were used for comparison. The Langmuir probe gave a plasma potential minus floating potential of 30 ± 5 eV, in good agreement with the carbon resistance probe result of ion energy ≤ 40 eV. The measured ion energy was consistent with the ion energy predicted from a model based upon divergent magnetic field extraction. Also, based upon physical sputtering of the carbon, the hydrogen fluence rate was determined to be 1 x 10 16 /cm 2 -sec for 50 Watts of incident microwave power. ECR hydrogen/helium plasmas were used to study preferential pumping of helium in candidate materials for tokamak pump-limiters: nickel, vanadium, aluminum, and nickel/aluminum multi-layers. Nickel and vanadium exhibited similar pumping capacities whereas aluminum showed a reduced capacity due to increased sputtering. A helium retention model based upon ion implantation ranges and sputtering rates agreed with the experimental data. A new multilayer/bilayer pumping concept showed improved pumping above that for single element films

PULSATIONS IN HYDROGEN BURNING LOW-MASS HELIUM WHITE DWARFS

International Nuclear Information System (INIS)

Steinfadt, Justin D. R.; Bildsten, Lars; Arras, Phil

2010-01-01

Helium core white dwarfs (WDs) with mass M ∼ sun undergo several Gyr of stable hydrogen burning as they evolve. We show that in a certain range of WD and hydrogen envelope masses, these WDs may exhibit g-mode pulsations similar to their passively cooling, more massive carbon/oxygen core counterparts, the ZZ Cetis. Our models with stably burning hydrogen envelopes on helium cores yield g-mode periods and period spacings longer than the canonical ZZ Cetis by nearly a factor of 2. We show that core composition and structure can be probed using seismology since the g-mode eigenfunctions predominantly reside in the helium core. Though we have not carried out a fully nonadiabatic stability analysis, the scaling of the thermal time in the convective zone with surface gravity highlights several low-mass helium WDs that should be observed in search of pulsations: NLTT 11748, SDSS J0822+2753, and the companion to PSR J1012+5307. Seismological studies of these He core WDs may prove especially fruitful, as their luminosity is related (via stable hydrogen burning) to the hydrogen envelope mass, which eliminates one model parameter.

Light particle production in spallation reactions induced by protons of 0.8-2.5 GeV incident kinetic energy

International Nuclear Information System (INIS)

Herbach, Claus-Michael; Enke, Michael; Boehm, Andreas

2002-01-01

Absolute production cross sections have been measured simultaneously for neutrons and light charged particles in 0.8-2.5 GeV proton induced spallation reactions for a series of target nuclei from aluminum up to uranium. The high detection efficiency both for neutral and charged evaporative particles provides an event-wise access to the amount of projectile energy dissipated into nuclear excitation. Various intra nuclear cascade plus evaporation models have been confronted with the experimental data showing large discrepancies for hydrogen and helium production. (author)

The October 2014 United States Treasury bond flash crash and the contributory effect of mini flash crashes.

Directory of Open Access Journals (Sweden)

Zachary S Levine

Full Text Available We investigate the causal uncertainty surrounding the flash crash in the U.S. Treasury bond market on October 15, 2014, and the unresolved concern that no clear link has been identified between the start of the flash crash at 9:33 and the opening of the U.S. equity market at 9:30. We consider the contributory effect of mini flash crashes in equity markets, and find that the number of equity mini flash crashes in the three-minute window between market open and the Treasury Flash Crash was 2.6 times larger than the number experienced in any other three-minute window in the prior ten weekdays. We argue that (a this statistically significant finding suggests that mini flash crashes in equity markets both predicted and contributed to the October 2014 U.S. Treasury Bond Flash Crash, and (b mini-flash crashes are important phenomena with negative externalities that deserve much greater scholarly attention.

The October 2014 United States Treasury bond flash crash and the contributory effect of mini flash crashes.

Science.gov (United States)

Levine, Zachary S; Hale, Scott A; Floridi, Luciano

2017-01-01

We investigate the causal uncertainty surrounding the flash crash in the U.S. Treasury bond market on October 15, 2014, and the unresolved concern that no clear link has been identified between the start of the flash crash at 9:33 and the opening of the U.S. equity market at 9:30. We consider the contributory effect of mini flash crashes in equity markets, and find that the number of equity mini flash crashes in the three-minute window between market open and the Treasury Flash Crash was 2.6 times larger than the number experienced in any other three-minute window in the prior ten weekdays. We argue that (a) this statistically significant finding suggests that mini flash crashes in equity markets both predicted and contributed to the October 2014 U.S. Treasury Bond Flash Crash, and (b) mini-flash crashes are important phenomena with negative externalities that deserve much greater scholarly attention.

Damage studies on tungsten due to helium ion irradiation

International Nuclear Information System (INIS)

Dutta, N.J.; Buzarbaruah, N.; Mohanty, S.R.

2014-01-01

Highlights: • Used plasma focus helium ion source to study radiation induced damage on tungsten. • Surface analyses confirm formation of micro-crack, bubbles, blisters, pinholes, etc. • XRD patterns confirm development of compressive stress due to thermal load. • Reduction in hardness value is observed in the case of exposed sample. - Abstract: Energetic and high fluence helium ions emitted in a plasma focus device have been used successfully to study the radiation induced damage on tungsten. The reference and irradiated samples were characterized by optical microscopy, field emission scanning electron microscopy, X-ray diffraction and by hardness testers. The micrographs of the irradiated samples at lower magnification show uniform mesh of cracks of micrometer width. However at higher magnification, various types of crystalline defects such as voids, pinholes, bubbles, blisters and microcracks are distinctly noticed. The prominent peaks in X-ray diffraction spectrum of irradiated samples are seen shifted toward higher Bragg angles, thus indicating accumulation of compressive stress due to the heat load delivered by helium ions. A marginal reduction in hardness of the irradiated sample is also noticed

Reducing carbon dioxide to products

Science.gov (United States)

Cole, Emily Barton; Sivasankar, Narayanappa; Parajuli, Rishi; Keets, Kate A

2014-09-30

A method reducing carbon dioxide to one or more products may include steps (A) to (C). Step (A) may bubble said carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode may reduce said carbon dioxide into said products. Step (B) may adjust one or more of (a) a cathode material, (b) a surface morphology of said cathode, (c) said electrolyte, (d) a manner in which said carbon dioxide is bubbled, (e), a pH level of said solution, and (f) an electrical potential of said divided electrochemical cell, to vary at least one of (i) which of said products is produced and (ii) a faradaic yield of said products. Step (C) may separate said products from said solution.

Liquid helium

CERN Document Server

Atkins, K R

1959-01-01

Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

Changes in visual sensitivity of the rabbit after a bleaching flash

International Nuclear Information System (INIS)

Courant, Daniel

1981-01-01

Electrical responses were simultaneously recorded at the photoreceptor level (a-wave of the ERG), at the pre-ganglionic retinal level (b-wave of the ERG) and at the post-retinal level (P1-wave of the superior colliculus and cortical VER). The relations of the different parameters of evoked responses with flash intensity were established. The changes and the recovery of this transfer function after the bleaching flash point out to the following conclusions: - Fast adaptation due to the ionic permeability change of the cellular membrane, resulting from the action of an internal transmitter, is different both with rods and cones. - In photopic adaptation, the a-wave slope temporarily exceeds the control value whereas the other parameters display a monotonous recovery. This suggests that, at the cone level, one product of degradation of the internal transmitter is a precursor of its formation. - The changes in amplitude-intensity relation are different between a- and b-waves, inducing a second mechanism of fast adaptation at a distal level of the retina. - There exists no supplementary adaptation at the ganglionic cells level since no difference is seen between the sensitivity curves obtained at the cortical and the ganglionic levels. (author) [fr

Energy efficient solvent regeneration process for carbon dioxide capture

Science.gov (United States)

Zhou, Shaojun; Meyer, Howard S.; Li, Shiguang

2018-02-27

A process for removing carbon dioxide from a carbon dioxide-loaded solvent uses two stages of flash apparatus. Carbon dioxide is flashed from the solvent at a higher temperature and pressure in the first stage, and a lower temperature and pressure in the second stage, and is fed to a multi-stage compression train for high pressure liquefaction. Because some of the carbon dioxide fed to the compression train is already under pressure, less energy is required to further compress the carbon dioxide to a liquid state, compared to conventional processes.

Hybrid simulation research on formation mechanism of tungsten nanostructure induced by helium plasma irradiation

Energy Technology Data Exchange (ETDEWEB)

Ito, Atsushi M., E-mail: ito.atsushi@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Takayama, Arimichi; Oda, Yasuhiro [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Tamura, Tomoyuki; Kobayashi, Ryo; Hattori, Tatsunori; Ogata, Shuji [Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Ohno, Noriyasu; Kajita, Shin [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yajima, Miyuki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Noiri, Yasuyuki [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yoshimoto, Yoshihide [University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Saito, Seiki [Kushiro National College of Technology, Kushiro, Hokkaido 084-0916 (Japan); Takamura, Shuichi [Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392 (Japan); Murashima, Takahiro [Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ward, Sendai 980-8578 (Japan); Miyamoto, Mitsutaka [Shimane University, Matsue, Shimane 690-8504 (Japan); Nakamura, Hiroaki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2015-08-15

The generation of tungsten fuzzy nanostructure by exposure to helium plasma is one of the important problems for the use of tungsten material as divertor plates in nuclear fusion reactors. In the present paper, the formation mechanisms of the helium bubble and the tungsten fuzzy nanostructure were investigated by using several simulation methods. We proposed the four-step process which is composed of penetration step, diffusion and agglomeration step, helium bubble growth step, and fuzzy nanostructure formation step. As the fourth step, the formation of the tungsten fuzzy nanostructure was successfully reproduced by newly developed hybrid simulation combining between molecular dynamics and Monte-Carlo method. The formation mechanism of tungsten fuzzy nanostructure observed by the hybrid simulation is that concavity and convexity of the surface are enhanced by the bursting of helium bubbles in the region around the concavity.

Use of helium in uranium exploration, Grants district

International Nuclear Information System (INIS)

DeVoto, R.H.; Mead, R.H.; Martin, J.P.; Bergquist, L.E.

1980-01-01

The continuous generation of inert helium gas from uranium and its daughter products provides a potentially useful means for remote detection of uranium deposits. The practicality of conducting helium surveys in the atmosphere, soil gas, and ground water to explore for buried uranium deposits has been tested in the Grants district and in the Powder River Basin of Wyoming. No detectable helium anomalies related to buried or surface uranium deposits were found in the atmosphere. However, reproducible helium-in-soil-gas anomalies were detected spatially related to uranium deposits buried from 50 to 800 ft deep. Diurnal and atmospheric effects can cause helium content variations (noise) in soil gas that are as great as the anomalies observed from instantaneous soil-gas samples. Cumulative soil-gas helium analyses, such as those obtained from collecting undisturbed soil samples and degassing them in the laboratory, may reveal anomalies from 5 to 100 percent above background. Ground water samples from the Grants district, New Mexico, and the Powder River Basin, Wyoming, have distinctly anomalous helium values spatially related to buried uranium deposits. In the southern Powder River Basin, helium values 20 to 200 percent above background occur 2 to 18 mile down the ground-water flow path from known uranium roll-front deposits. In the Grants district, helium contents 40 to 700 percent above background levels are present in ground waters from the host sandstone in the vicinity of uranium deposits and from aquifers up to 3,000 ft stratigraphically above the deep uranium deposits. The use of helium in soil and ground-water surveys, along with uranium and radon analyses of the same materials, is strongly recommended is expensive, deep, uranium-exploration programs such as those being conducted in the Grants district

Buried melting in germanium implanted silicon by millisecond flash lamp annealing

International Nuclear Information System (INIS)

Voelskow, Matthias; Yankov, Rossen; Skorupa, Wolfgang; Pezoldt, Joerg; Kups, Thomas

2008-01-01

Flash lamp annealing in the millisecond range has been used to induce buried melting in silicon. For this purpose high dose high-energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp treatment at high energy densities leads to local melting of the germanium rich layer. The thickness of the molten layer has been found to depend on the irradiation energy density. During the cool-down period, epitaxial crystallization takes place resulting in a largely defect-free layer

CALCULATED REGENERATOR PERFORMANCE AT 4 K WITH HELIUM-4 AND HELIUM-3

International Nuclear Information System (INIS)

Radebaugh, Ray; Huang Yonghua; O'Gallagher, Agnes; Gary, John

2008-01-01

The helium-4 working fluid in regenerative cryocoolers operating with the cold end near 4 K deviates considerably from an ideal gas. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature. Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators. An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power. The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN3.3, which was used to model regenerator performance with either helium-4 or helium-3. With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers. The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared. The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies

Membrane potential and microsecond to millisecond delayed light emission after a single excitation flash in isolated chloroplasts

International Nuclear Information System (INIS)

Jursinic, P.; Govindjee; Wraight, C.A.

1978-01-01

The effect of light-induced and salt-jump induced membrane potential on microsecond and millisecond delayed light emission from chloroplasts, following a single 10 ns flash, have been studied. Microsecond delayed light emission is shown to be independent of the membrane potential contrary to proposals that the activation energy for delayed light emission can be modulated by transmembrane electric fields. This result is discussed in terms of the possible origin of this short-lived emission. Millisecond delayed light after a single excitation flash is enhanced by membrane potential only if a proton gradient is present. By measuring changes in ms delayed light caused by simultaneous injection of KCl and Na-benzoate (which creates a proton gradient) in the presence of valinomycin, the light-induced potential generated across the thylakoid membrane by a single excitation flash was calibrated and found to be 128 +- 10 mV in agreement with the recent measurements of Zickler and Witt, (FEBS Lett. 66, 142-148 (1976)), based on voltage-dependent ionophores. It is concluded that the secondary charges that give rise to ms delayed light, after a single flash, do not fully span the membrane. (author)

DIRCM FLASH Flight Tests

National Research Council Canada - National Science Library

Molocher, Bernhard; Kaltenecker, Anton; Thum-Jaeger, Andrea; Regensburger, Martin; Formery, Martin

2005-01-01

.... FLASH operation is as follows: After handover following an alarm from the missile warning system FLASH enters autonomous passive tracking mode for tracking a missiles and sending a laser beam onto the missile...

Prodigious degassing of a billion years of accumulated radiogenic helium at Yellowstone

Science.gov (United States)

Lowenstern, Jacob B.; Evans, William C.; Bergfeld, D.; Hunt, Andrew G.

2014-01-01

Helium is used as a critical tracer throughout the Earth sciences, where its relatively simple isotopic systematics is used to trace degassing from the mantle, to date groundwater and to time the rise of continents1. The hydrothermal system at Yellowstone National Park is famous for its high helium-3/helium-4 isotope ratio, commonly cited as evidence for a deep mantle source for the Yellowstone hotspot2. However, much of the helium emitted from this region is actually radiogenic helium-4 produced within the crust by α-decay of uranium and thorium. Here we show, by combining gas emission rates with chemistry and isotopic analyses, that crustal helium-4 emission rates from Yellowstone exceed (by orders of magnitude) any conceivable rate of generation within the crust. It seems that helium has accumulated for (at least) many hundreds of millions of years in Archaean (more than 2.5 billion years old) cratonic rocks beneath Yellowstone, only to be liberated over the past two million years by intense crustal metamorphism induced by the Yellowstone hotspot. Our results demonstrate the extremes in variability of crustal helium efflux on geologic timescales and imply crustal-scale open-system behaviour of helium in tectonically and magmatically active regions.

Flash pyrolysis, a process for utilizing contaminated wood; Flash-Pyrolyse - eine Moeglichkeit der stofflichen Verwertung von kontaminiertem Holz

Energy Technology Data Exchange (ETDEWEB)

Meier, D; Wehlte, S; Faix, O [Bundesforschungsanstalt fuer Forst- und Holzwirtschaft, Hamburg (Germany). Inst. fuer Holzchemie und Chemische Technologie des Holzes

1997-12-31

Flash pyrolysis of wood treated with common pesticides poses no technical probelms. Product yields, with a maximum oil yield at 475 C, are similar to those of untreated wood. Most of the heavy metals are retained by the coal while a small part aheres to the coal layer of the sand bed. The resulting pyrolysis oil contains neither chromium nor copper. (orig) [Deutsch] Die Flash-Pyrolyse der mit den gaengigsten Schutzmitteln behandelten Hoelzer bereitet verfahrenstechnisch keine Probleme. Auch die Produktausbeuten, mit einem oelmaximum bei 475 C, aehneln denen von naturbelassenem Holz. Der groesste Teil der Schwermetalle wurde an die Kohle gebunden, ein geringer Teil blieb auf der Kohleschicht des Sandes haften. Im Hauptprodukt Pyrolyseoel konnten weder Chrom noch Kupfer nachgewiesen werden. (orig)

Flash pyrolysis, a process for utilizing contaminated wood; Flash-Pyrolyse - eine Moeglichkeit der stofflichen Verwertung von kontaminiertem Holz

Energy Technology Data Exchange (ETDEWEB)

Meier, D.; Wehlte, S.; Faix, O. [Bundesforschungsanstalt fuer Forst- und Holzwirtschaft, Hamburg (Germany). Inst. fuer Holzchemie und Chemische Technologie des Holzes

1996-12-31

Flash pyrolysis of wood treated with common pesticides poses no technical probelms. Product yields, with a maximum oil yield at 475 C, are similar to those of untreated wood. Most of the heavy metals are retained by the coal while a small part aheres to the coal layer of the sand bed. The resulting pyrolysis oil contains neither chromium nor copper. (orig) [Deutsch] Die Flash-Pyrolyse der mit den gaengigsten Schutzmitteln behandelten Hoelzer bereitet verfahrenstechnisch keine Probleme. Auch die Produktausbeuten, mit einem oelmaximum bei 475 C, aehneln denen von naturbelassenem Holz. Der groesste Teil der Schwermetalle wurde an die Kohle gebunden, ein geringer Teil blieb auf der Kohleschicht des Sandes haften. Im Hauptprodukt Pyrolyseoel konnten weder Chrom noch Kupfer nachgewiesen werden. (orig)

Mechanical property changes induced in structural alloys by neutron irradiations with different helium to displacement ratios*1

Science.gov (United States)

Mansur, L. K.; Grossbeck, M. L.

1988-07-01

Effects of helium on mechanical properties of irradiated structural materials are reviewed. In particular, variations in response to the ratio of helium to displacement damage serve as the focus. Ductility in creep and tensile tests is emphasized. A variety of early work has led to the current concentration on helium effects for fusion reactor materials applications. A battery of techniques has been developed by which the helium to displacement ratio can be varied. Our main discussion is devoted to the techniques of spectral tailoring and isotopic alloying currently of interest for mixed-spectrum reactors. Theoretical models of physical mechanisms by which helium interacts with displacement damage have been developed in terms of hardening to dislocation motion and grain boundary cavitation. Austenitic stainless steels, ferritic/martensitic steels and vanadium alloys are considered. In each case, work at low strain rates, where the main problems may lie, at the helium to displacement ratios appropriate to fusion reactor materials is lacking. Recent experimental evidence suggests that both in-reactor and high helium results may differ substantially from post-irradiation or low helium results. It is suggested that work in these areas is especially needed.

Medium range forecasting of Hurricane Harvey flash flooding using ECMWF and social vulnerability data

Science.gov (United States)

Pillosu, F. M.; Jurlina, T.; Baugh, C.; Tsonevsky, I.; Hewson, T.; Prates, F.; Pappenberger, F.; Prudhomme, C.

2017-12-01

During hurricane Harvey the greater east Texas area was affected by extensive flash flooding. Their localised nature meant they were too small for conventional large scale flood forecasting systems to capture. We are testing the use of two real time forecast products from the European Centre for Medium-range Weather Forecasts (ECMWF) in combination with local vulnerability information to provide flash flood forecasting tools at the medium range (up to 7 days ahead). Meteorological forecasts are the total precipitation extreme forecast index (EFI), a measure of how the ensemble forecast probability distribution differs from the model-climate distribution for the chosen location, time of year and forecast lead time; and the shift of tails (SOT) which complements the EFI by quantifying how extreme an event could potentially be. Both products give the likelihood of flash flood generating precipitation. For hurricane Harvey, 3-day EFI and SOT products for the period 26th - 29th August 2017 were used, generated from the twice daily, 18 km, 51 ensemble member ECMWF Integrated Forecast System. After regridding to 1 km resolution the forecasts were combined with vulnerable area data to produce a flash flood hazard risk area. The vulnerability data were floodplains (EU Joint Research Centre), road networks (Texas Department of Transport) and urban areas (Census Bureau geographic database), together reflecting the susceptibility to flash floods from the landscape. The flash flood hazard risk area forecasts were verified using a traditional approach against observed National Weather Service flash flood reports, a total of 153 reported flash floods have been detected in that period. Forecasts performed best for SOT = 5 (hit ratio = 65%, false alarm ratio = 44%) and EFI = 0.7 (hit ratio = 74%, false alarm ratio = 45%) at 72 h lead time. By including the vulnerable areas data, our verification results improved by 5-15%, demonstrating the value of vulnerability information within

Crystal orientation effects on helium ion depth distributions and adatom formation processes in plasma-facing tungsten

International Nuclear Information System (INIS)

Hammond, Karl D.; Wirth, Brian D.

2014-01-01

We present atomistic simulations that show the effect of surface orientation on helium depth distributions and surface feature formation as a result of low-energy helium plasma exposure. We find a pronounced effect of surface orientation on the initial depth of implanted helium ions, as well as a difference in reflection and helium retention across different surface orientations. Our results indicate that single helium interstitials are sufficient to induce the formation of adatom/substitutional helium pairs under certain highly corrugated tungsten surfaces, such as (1 1 1)-orientations, leading to the formation of a relatively concentrated layer of immobile helium immediately below the surface. The energies involved for helium-induced adatom formation on (1 1 1) and (2 1 1) surfaces are exoergic for even a single adatom very close to the surface, while (0 0 1) and (0 1 1) surfaces require two or even three helium atoms in a cluster before a substitutional helium cluster and adatom will form with reasonable probability. This phenomenon results in much higher initial helium retention during helium plasma exposure to (1 1 1) and (2 1 1) tungsten surfaces than is observed for (0 0 1) or (0 1 1) surfaces and is much higher than can be attributed to differences in the initial depth distributions alone. The layer thus formed may serve as nucleation sites for further bubble formation and growth or as a source of material embrittlement or fatigue, which may have implications for the formation of tungsten “fuzz” in plasma-facing divertors for magnetic-confinement nuclear fusion reactors and/or the lifetime of such divertors.

New helium spectrum variable and a new helium-rich star

International Nuclear Information System (INIS)

Walborn, N.R.

1974-01-01

HD 184927, known previously as a helium-rich star, has been found to have a variable helium spectrum; the equivalent widths of five He I lines are larger by an average of 46 percent on a 1974 spectrogram than on one obtained with the same equipment in 1970. HD 186205 has been found to be a new, pronounced helium-rich star. (auth)

Ion source based on Penning discharge for production of doubly charged helium ions

Directory of Open Access Journals (Sweden)

V. I. Voznyi

2017-11-01

Full Text Available The article presents the results of operation of ion source with Penning discharge developed in the IAP of NAS of Ukraine to produce doubly charged helium ions He2+ beam and to increase the energy of accelerated ions up to 3.2 MeV. This energy is necessary for ERDA channel when measuring hydrogen concentration in the structural materials used in nuclear engineering. The ion source parameters are the following: discharge voltage is 6 kV, discharge current is 0.8 - 1.2 mA, the current of singly charged helium ions He+ 24 μA, the current of doubly charged helium ions He2+ 0.5 μA.

Flash Extraction and Physicochemical Characterization of Oil from Elaeagnus mollis Diels Seeds.

Science.gov (United States)

Kan, Lina; Wang, Lin; Ding, Qingzhen; Wu, Yanwen; Ouyang, Jie

2017-04-03

A flash extraction method was used to isolate Elaeagnus mollis oil (EMO). The optimal extraction parameters, sample/solvent ratio and extraction temperature, were determined to be 1:10 (g/mL) and 40°C, respectively. Especially, the extraction yield reached 49.30% when the extraction time was as short as 2 min. No obvious difference was observed in fatty acid composition, iodine value, saponification number, total phenolic content and tocopherol content between flash-extracted EMO and Soxhlet-extracted EMO, but their physicochemical values were lower than those of cold-pressed EMO. Cold-pressed EMO had higher oxidation stability, DPPH (1-diphenyl-2-picrylhydrazyl) and hydroxyl radical-scavenging activities than flash-extracted EMO and Soxlet extracted EMO. The flash extraction is demonstrated to be an alternative, efficient method for the vegetable oil production.

Flashing inception in flowing liquids

International Nuclear Information System (INIS)

Jones, O.C. Jr.

1979-01-01

The inception of net vaporization in flashing flows is examined. It is suggested that the flashing inception can be expressed as two additive effects. One is due to the static decompression which is a function of the spinodal limit and also of the expansion rate. The other effect which is a function of Reynolds number and flashing index, is due to the turbulent fluctuations of the flowing liquid. It is shown that by taking a three standard deviation band on the turbulent velocity fluctuations, an adequate representation of the inverse mass flux effect on flashing inception for existing data is obtained

Napping-Ultra Flash Profile as a Tool for Category Identification and Subsequent Model System Formulation of Caramel Corn Products.

Science.gov (United States)

Mayhew, Emily; Schmidt, Shelly; Lee, Soo-Yeun

2016-07-01

In a novel approach to formulation, the flash descriptive profiling technique Napping-Ultra Flash Profile (Napping-UFP) was used to characterize a wide range of commercial caramel corn products. The objectives were to identify product categories, develop model systems based on product categories, and correlate analytical parameters with sensory terms generated through the Napping-UFP exercise. In one 2 h session, 12 panelists participated in 4 Napping-UFP exercises, describing and grouping, on a 43×56 cm paper sheet, 12 commercial caramel corn samples by degree of similarity, globally and in terms of aroma-by-mouth, texture, and taste. The coordinates of each sample's placement on the paper sheet and descriptive terms generated by the panelists were used to conduct Multiple Factor Analysis (MFA) and hierarchical clustering of the samples. Strong trends in the clustering of samples across the 4 Napping-UFP exercises resulted in the determination of 3 overarching types of commercial caramel corn: "small-scale dark" (typified by burnt, rich caramel corn), "large-scale light" (typified by light and buttery caramel corn), and "large-scale dark" (typified by sweet and molasses-like caramel corn). Representative samples that best exemplified the properties of each category were used as guides in the formulation of 3 model systems that represent the spread of commercial caramel corn products. Analytical testing of the commercial products, including aw measurement, moisture content determination, and thermal characterization via differential scanning calorimetry, were conducted and results related to sensory descriptors using Spearman's correlation. © 2016 Institute of Food Technologists®

Statistical Evolution of the Lightning Flash

Science.gov (United States)

Zoghzoghy, F. G.; Cohen, M.; Said, R.; Inan, U. S.

2012-12-01

Natural lightning is one of the most fascinating and powerful electrical processes on Earth. To date, the physics behind this natural phenomenon are not fully understood, due primarily to the difficulty of obtaining measurements inside thunderstorms and to the wide range of timescales involved (from nanoseconds to seconds). Our aim is to use accurate lightning geo-location data from the National Lightning Detection Network (NLDN) to study statistical patterns in lightning, taking advantage of the fact that millions of lightning flashes occur around the globe every day. We present two sets of results, one involving the patterns of flashes in a storm, and a second involving the patterns of strokes in a flash. These patterns can provide a surrogate measure of the timescales and the spatial extents of the underlying physical processes. First, we study the timescales of charge buildup inside thunderstorms. We find that, following a lightning flash, the probability of another neighboring flash decreases and takes tens of seconds to recover. We find that this suppression effect is a function of flash type, stroke peak current, cloud-to-ground (CG) stroke multiplicity, and other lightning and geographical parameters. We find that the probabilities of subsequent flashes are more suppressed following oceanic lightning, or following flashes with higher peak currents and/or higher multiplicities (for CG flashes). Second, we use NLDN data to study the evolution of the strokes within a CG flash. A CG flash typically includes multiple return strokes, which can occur in the same channel or in multiple channels within a few kilometers. We cluster NLDN stroke data into flashes and produce the probability density function of subsequent strokes as a function of distance and time-delays relative to the previous stroke. Using this technique, we investigate processes which occur during the CG lightning flash with nanosecond to millisecond timescales. For instance, our results suggest

Advanced CSiC composites for high-temperature nuclear heat transport with helium, molten salts, and sulphur-iodine thermochemical hydrogen process fluids

International Nuclear Information System (INIS)

Peterson, P.F.; Forsberg, Ch.W.; Pickard, P.S.

2004-01-01

This paper discusses the use of liquid-silicon-impregnated (LSI) carbon-carbon composites for the development of compact and inexpensive heat exchangers, piping, vessels and pumps capable of operating in the temperature range of 800 to 1 100 deg C with high-pressure helium, molten fluoride salts, and process fluids for sulfur-iodine thermochemical hydrogen production. LSI composites have several potentially attractive features, including ability to maintain nearly full mechanical strength to temperatures approaching 1 400 deg C, inexpensive and commercially available fabrication materials, and the capability for simple forming, machining and joining of carbon-carbon performs, which permits the fabrication of highly complex component geometries. In the near term, these materials may prove to be attractive for use with a molten-salt intermediate loop for the demonstration of hydrogen production with a gas-cooled high temperature reactor. In the longer term, these materials could be attractive for use with the molten-salt cooled advanced high temperature reactor, molten salt reactors, and fusion power plants. (author)

Carbon dioxide production in animal houses

DEFF Research Database (Denmark)

Pedersen, Søren; Blanes-Vidal, Victoria; Joergensen, H.

2008-01-01

cellars are emptied regularly in a four weeks interval. Due to a high and variable carbon dioxide production in deep straw litter houses and houses with indoor storage of manure longer than four weeks, we do not recommend to calculate the ventilation flow based on the carbon dioxide concentration......This article deals with carbon dioxide production from farm animals; more specifically, it addresses the possibilities of using the measured carbon dioxide concentration in animal houses as basis for estimation of ventilation flow (as the ventilation flow is a key parameter of aerial emissions from...... animal houses). The investigations include measurements in respiration chambers and in animal houses, mainly for growing pigs and broilers. Over the last decade a fixed carbon dioxide production of 185 litres per hour per heat production unit, hpu (i.e. 1000 W of the total animal heat production at 20o...

Positron annihilation investigation and nuclear reaction analysis of helium and oxygen-implanted zirconia

International Nuclear Information System (INIS)

Grynszpan, R.I.; Saude, S.; Anwand, W.; Brauer, G.

2005-01-01

Since irradiation affects in-service properties of zirconia, we investigated the fluence dependence on production and thermal stability of defects induced by helium and oxygen-ion implantation in single crystals of yttria-fully-stabilized zirconia. In either case, depth profiling by slow positron implantation spectroscopy (SPIS) detects a distribution of vacancy-type defects peaking at 60% of the projected ion range R p . Owing to the saturation of positron-trapping occurring for low fluences, which depends on the ion mass, we could estimate a critical size of clusters ranging from 0.4 to 1.6 nm. The lack of SPIS-evidence of an open-volume excess at R p is explained by the presence of over-pressurized gas bubbles. This assumption is confirmed by Nuclear Reaction Analysis of 3 He concentration profiles, which shows that helium remains partly trapped at R p , even after annealing above 400 o C

Minimizing activated carbons production cost

International Nuclear Information System (INIS)

Stavropoulos, G.G.; Zabaniotou, A.A.

2009-01-01

A detailed economic evaluation of activated carbons production process from various raw materials is undertaken using the conventional economic indices (ROI, POT, and NPV). The fundamental factors that affect production cost were taken into account. It is concluded that for an attractive investment in activated carbons production one should select the raw material with the highest product yield, adopt a chemical activation production scheme and should base product price on product-surface area (or more generally on product adsorption capacity for the adsorbate in consideration). A raw material that well meets the above-mentioned criteria is petroleum coke but others are also promising (charcoals, and carbon black). Production cost then can be optimized by determining its minimum value of cost that results from the intercept between the curves of plant capacity and raw material cost - if any. Taking into account the complexity of such a techno-economic analysis, a useful suggestion could be to start the evaluations from a plant capacity corresponding to the break-even point, i. e. the capacity at which income equals production cost. (author)

Spatial Distributions of Metal Atoms During Carbon SWNTs Formation: Measurements and Modelling

Science.gov (United States)

Cau, M.; Dorval, N.; Attal-Tretout, B.; Cochon, J. L.; Loiseau, A.; Farhat, S.; Hinkov, I.; Scott, C. D.

2004-01-01

Experiments and modelling have been undertaken to clarify the role of metal catalysts during single-wall carbon nanotube formation. For instance, we wonder whether the metal catalyst is active as an atom, a cluster, a liquid or solid nanoparticle [1]. A reactor has been developed for synthesis by continuous CO2-laser vaporisation of a carbon-nickel-cobalt target in laminar helium flow. The laser induced fluorescence technique [2] is applied for local probing of gaseous Ni, Co and CZ species throughout the hot carbon flow of the target heated up to 3500 K. A rapid depletion of C2 in contrast to the spatial extent of metal atoms is observed in the plume (Fig. 1). This asserts that C2 condenses earlier than Ni and Co atoms.[3, 4]. The depletion is even faster when catalysts are present. It may indicate that an interaction between metal atoms and carbon dimers takes place in the gas as soon as they are expelled from the target surface. Two methods of modelling are used: a spatially I-D calculation developed originally for the arc process [5], and a zero-D time dependent calculation, solving the chemical kinetics along the streamlines [6]. The latter includes Ni cluster formation. The peak of C2 density is calculated close to the target surface where the temperature is the highest. In the hot region, C; is dominant. As the carbon products move away from the target and mix with the ambient helium, they recombine into larger clusters, as demonstrated by the peak of C5 density around 1 mm. The profile of Ni-atom density compares fairly well with the measured one (Fig. 2). The early increase is due to the drop of temperature, and the final decrease beyond 6 mm results from Ni cluster formation at the eutectic temperature (approx.1600 K).

Adsorption removal of carbon dioxide from the helium coolant of high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

Varezhin, A.V.; Fedoseenkov, A.N.; Khrulev, A.A.; Metlik, I.V.; Zel venskii, Y.D.

1986-01-01

This paper conducts experiments on the removal of CO 2 from helium by means of a Soviet-made adsorbent under the conditions characteristic of high-temperature gas-cooled reactor cleaning systems. The adsorption of CO 2 from helium was studied under dynamic conditions with a fixed layer of adsorbent in a flow-through apparatus with an adsorber 16 mm in diameter. The analysis of the helium was carried out by means of a TVT chromatograph. In order to compare the adsorption of CO 2 on CaA zeolite under dynamic conditions from the helium stream under pressure with the equilibrium adsorption on the basis of pure CO 2 , the authors determined the adsorption isotherm at 293 K by the volumetric method over a range of CO 2 equilibrium pressures from 260 to 11,970 Pa. Reducing the adsorption temperature to 273 K leads to a considerable reduction in the energy costs for regeneration, owing to the increase in adsorption and the decrease in the number of regeneration cycles; the amount of the heating gas used is reduced to less than half

Supercritical Helium Cooling of the LHC Beam Screens

CERN Document Server

Hatchadourian, E; Tavian, L

1998-01-01

The cold mass of the LHC superconducting magnets, operating in pressurised superfluid helium at 1.9 K, must be shielded from the dynamic heat loads induced by the circulating particle beams, by means of beam screens maintained at higher temperature. The beam screens are cooled between 5 and 20 K by forced flow of weakly supercritical helium, a solution which avoids two-phase flow in the long, narr ow cooling channels, but still presents a potential risk of thermohydraulic instabilities. This problem has been studied by theoretical modelling and experiments performed on a full-scale dedicated te st loop.

Helium generation and diffusion in graphite and some carbides

International Nuclear Information System (INIS)

Holt, J.B.; Guinan, M.W.; Hosmer, D.W.; Condit, R.H.; Borg, R.J.

1976-01-01

The cross section for the generation of helium in neutron irradiated carbon was found to be 654 mb at 14.4 MeV and 744 mb at 14.9 MeV. Extrapolating to 14.1 MeV (the fusion reactor spectrum) gives 615 mb. The diffusion of helium in dense polycrystalline graphite and in pyrographite was measured and found to be D = 7.2 x 10 -7 m 2 s -1 exp (-80 kJ/RT). It is assumed that diffusion is primarily in the basal plane direction in crystals of the graphite. In polycrystalline graphite the path length is a factor of √2 longer than the measured distance due to the random orientation mismatch between successive grains. Isochronal anneals (measured helium release as the specimen is steadily heated) were run and maximum release rates were found at 200 0 C in polycrystalline graphite, 1000 0 C in pyrographite, 1350 0 C in boron carbide, and 1350 0 and 2400 0 C (two peaks) in silicon carbide. It is concluded that in these candidates for curtain materials in fusion reactors the helium releases can probably occur without bubble formation in graphites, may occur in boron carbide, but will probably cause bubble formation in silicon carbide. 7 figures

Use of Helium-3 and Tritium tracers in oceanography

International Nuclear Information System (INIS)

Andrie, Chantal

1987-01-01

As tritium considered as a transient tracer has become one of the most promising tool for the study of oceanic circulation and of the ocean capacity to absorb anthropogenic carbon, and as the simultaneous use of its radioactive descendant, Helium-3, brings an additional information (together, these tracers build up a clock in the study of water masses), and as all helium-3 and tritium measurements are made by mass spectroscopy, this research thesis addresses the analytical process, the detection limit, and the method reproducibility associated with this use of both tracers. The author reports and discusses helium-3 data obtained during a measurement campaign which allowed the localisation of an active source and the evidence of an intermediate back current, and tritium data obtained during another measurement campaign which allowed the description of the high time variability of convection processes, and an assessment of water renewal delays and of some deep water circulations. He also reports and discusses the simultaneous use of helium-3 data and tritium data to localize areas where convection processes occur. A theoretical approach to this simultaneous use is proposed which uses a mixing model which distinguishes the venting transit time. Measurement campaigns were performed in Red Sea, western Mediterranean Sea, and north-eastern Atlantic Ocean [fr

Helium production for 0.8-2.5 GeV proton induced spallation reactions, damage induced in metallic window materials

International Nuclear Information System (INIS)

Hilscher, D.; Herbach, C.-M.; Jahnke, U.; Tishchenko, V.; Enke, M.; Filges, D.; Goldenbaum, F.; Neef, R.-D.; Nuenighoff, K.; Paul, N.; Schaal, H.; Sterzenbach, G.; Letourneau, A.; Boehm, A.; Galin, J.; Lott, B.; Peghaire, A.; Pienkowski, L.

2001-01-01

Production cross-sections for neutrons and charged particles as well as excitation energy distributions in spallation reactions were measured recently by the NESSI-collaboration and have been employed to test different intra nuclear cascade models and the subsequent evaporation. The INCL/GEMINI code, which describes best the experimental data has been employed to calculate the damage cross-sections in Fe and Ta as well as the He/dpa ratio as a function of proton energy. For the same amount of neutron production in a typical target of a spallation neutron source the proton beam induced radiation damage in an Fe window is shown to decrease almost linearly with proton energy. For heavier materials such as Ta a similar decrease of the radiation damage is found only for energies above about 3 GeV

Experimental method to determine the role of helium in neutron-induced microstructural evolution

International Nuclear Information System (INIS)

Gelles, D.S.; Garner, F.A.

1978-12-01

A method is presented which allows the determination of the role of helium on microstructural evolution in complex alloys and which avoids many of the problems associated with other simulation experiments. It involves a direct comparison of the materials' response to a primary difference in fission and fusion environments, namely the rate of helium generation. This is accomplished by irradiating specimens in a fission reactor and conducting microstructural analyses which concentrate on alloy matrix regions adjacent to precipitates rich in boron or nitrogen. Procedures are outlined for calculation of background and injected helium levels as well as displacement doses generated by neutrons and alpha particles. An example of the analysis method is shown for an experimental austenitic stainless steel containing boride particles and irradiated to 3 and 7 x 10 22 n/cm 2

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS

Energy Technology Data Exchange (ETDEWEB)

Dady Dadyburjor; Philip R. Biedler; Chong Chen; L. Mitchell Clendenin; Manoj Katakdaunde; Elliot B. Kennel; Nathan D. King; Liviu Magean; Peter G. Stansberry; Alfred H. Stiller; John W. Zondlo

2004-08-31

This Department of Energy National Energy Technology Laboratory sponsored project developed carbon products, using mildly hydrogenated solvents to extract the organic portion of coal to create synthetic pitches, cokes, carbon foam and carbon fibers. The focus of this effort was on development of lower cost solvents, milder hydrogenation conditions and improved yield in order to enable practical production of these products. This technology is needed because of the long-term decline in production of domestic feedstocks such as petroleum pitch and coal tar pitch. Currently, carbon products represents a market of roughly 5 million tons domestically, and 19 million tons worldwide. Carbon products are mainly derived from feedstocks such as petroleum pitch and coal tar pitch. The domestic supply of petroleum pitch is declining because of the rising price of liquid fuels, which has caused US refineries to maximize liquid fuel production. As a consequence, the long term trend has a decline in production of petroleum pitch over the past 20 years. The production of coal tar pitch, as in the case of petroleum pitch, has likewise declined significantly over the past two decades. Coal tar pitch is a byproduct of metallurgical grade coke (metcoke) production. In this industry, modern metcoke facilities are recycling coal tar as fuel in order to enhance energy efficiency and minimize environmental emissions. Metcoke production itself is dependent upon the production requirements for domestic steel. Hence, several metcoke ovens have been decommissioned over the past two decades and have not been replaced. As a consequence sources of coal tar are being taken off line and are not being replaced. The long-term trend is a reduction in coal tar pitch production. Thus import of feedstocks, mainly from Eastern Europe and China, is on the rise despite the relatively large transportation cost. To reverse this trend, a new process for producing carbon products is needed. The process must be

Menopausal Hot Flashes and White Matter Hyperintensities

Science.gov (United States)

Thurston, Rebecca C.; Aizenstein, Howard J.; Derby, Carol A.; Sejdić, Ervin; Maki, Pauline M.

2015-01-01

Objective Hot flashes are the classic menopausal symptom. Emerging data links hot flashes to cardiovascular disease (CVD) risk, yet how hot flashes are related to brain health is poorly understood. We examined the relationship between hot flashes - measured via physiologic monitor and self-report - and white matter hyperintensities (WMH) among midlife women. Methods Twenty midlife women ages 40-60 without clinical CVD, with their uterus and both ovaries, and not taking hormone therapy were recruited. Women underwent 24 hours of ambulatory physiologic and diary hot flash monitoring to quantify hot flashes; magnetic resonance imaging to assess WMH burden; 72 hours of actigraphy and questionnaires to quantify sleep; and a blood draw, questionnaires, and physical measures to quantify demographics and CVD risk factors. Test of a priori hypotheses regarding relations between physiologically-monitored and self-reported wake and sleep hot flashes and WMH were conducted in linear regression models. Results More physiologically-monitored hot flashes during sleep were associated with greater WMH, controlling for age, race, and body mass index [beta(standard error)=.0002 (.0001), p=.03]. Findings persisted controlling for sleep characteristics and additional CVD risk factors. No relations were observed for self-reported hot flashes. Conclusions More physiologically-monitored hot flashes during sleep were associated with greater WMH burden among midlife women free of clinical CVD. Results suggest that relations between hot flashes and CVD risk observed in the periphery may extend to the brain. Future work should consider the unique role of sleep hot flashes in brain health. PMID:26057822

Liquid helium target

International Nuclear Information System (INIS)

Fujii, Y.; Kitami, T.; Torikoshi, M.

1984-12-01

A liquid helium target system has been built and used for the experiment on the reaction 4 He(γ, p). The target system has worked satisfactorily; the consumption rate of liquid helium is 360 ml/h and the cryogenic system retains liquid helium for about ten hours. The structure, operation and performance of the target system are reported. (author)

Foundation Flash CS4 for Designers

CERN Document Server

Green, Tom

2008-01-01

In this book, you'll learn:* How to create effective animations using the new Motion Editor and animation tools * How to use the new 3D features to animate objects in 3D space * Best-practice tips and techniques from some of the top Flash practitioners on the planet * How to create captioned video and full-screen video, and deploy HD video using Flash * Techniques for using the Flash UI components as well as XML documents to create stunning,interactive presentations If you're a Flash designer looking for a solid overview of Flash CS4, this book is for you. Through the use of solid and practica

Effect of carbon sources on the aggregation of photo fermentative bacteria induced by L-cysteine for enhancing hydrogen production.

Science.gov (United States)

Xie, Guo-Jun; Liu, Bing-Feng; Ding, Jie; Wang, Qilin; Ma, Chao; Zhou, Xu; Ren, Nan-Qi

2016-12-01

Poor flocculation of photo fermentative bacteria resulting in continuous biomass washout from photobioreactor is a critical challenge to achieve rapid and stable hydrogen production. In this work, the aggregation of Rhodopseudomonas faecalis RLD-53 was successfully developed in a photobioreactor and the effects of different carbon sources on hydrogen production and aggregation ability were investigated. Extracellular polymeric substances (EPS) production by R. faecalis RLD-53 cultivated using different carbon sources were stimulated by addition of L-cysteine. The absolute ζ potentials of R. faecalis RLD-53 were considerably decreased with addition of L-cysteine, and aggregation barriers based on DLVO dropped to 15-43 % of that in control groups. Thus, R. faecalis RLD-53 flocculated effectively, and aggregation abilities of strain RLD-53 cultivated with acetate, propionate, lactate and malate reached 29.35, 32.34, 26.07 and 24.86 %, respectively. In the continuous test, hydrogen-producing activity was also promoted and reached 2.45 mol H 2 /mol lactate, 3.87 mol H 2 /mol propionate and 5.10 mol H 2 /mol malate, respectively. Therefore, the aggregation of R. faecalis RLD-53 induced by L-cysteine is independent on the substrate types, which ensures the wide application of this technology to enhance hydrogen recovery from wastewater dominated by different organic substrates.

Synergistic effect of displacement damage, helium and hydrogen on microstructural change of SiC/SiC composites fabricated by reaction bonding process

Energy Technology Data Exchange (ETDEWEB)

Taguchi, T.; Igawa, N.; Wakai, E.; Jitsukawa, S. [Japan Atomic Energy Agency, Naga-gun, Ibaraki-ken (Japan); Hasegawa, A. [Tohoku Univ., Dept. of Quantum Science and Energy Engr., Sendai (Japan)

2007-07-01

Full text of publication follows: Continuous silicon carbide (SiC) fiber reinforced SiC matrix (SiC/SiC) composites are known to be attractive candidate materials for first wall and blanket components in fusion reactors. In the fusion environment, helium and hydrogen are produced and helium bubbles can be formed in the SiC by irradiation of 14-MeV neutrons. Authors reported the synergistic effect of helium and hydrogen as transmutation products on swelling behavior and microstructural change of the SiC/SiC composites fabricated by chemical vapor infiltration (CVI) process. Authors also reported about the fabrication of high thermal conductive SiC/SiC composites by reaction bonding (RB) process. The matrix fabricated by RB process has different microstructures such as bigger grain size of SiC and including Si phase as second phase from that by CVI process. It is, therefore, investigated the synergistic effect of displacement damage, helium and hydrogen as transmutation products on the microstructure of SiC/SiC composite by RB process in this study. The SiC/SiC composites by RB process were irradiated by the simultaneous triple ion irradiation (Si{sup 2+}, He{sup +} and H{sup +}) at 800 and 1000 deg. C. The displacement damage was induced by 6.0 MeV Si{sup 2+} ion irradiation up to 10 dpa. The microstructures of irradiated SiC/SiC composites by RB process were observed by TEM. The double layer of carbon and SiC as interphase between fiber and matrix by a chemical vapor deposition (CVD) was coated on SiC fibers in the SiC/SiC composites by RB process. The TEM observation revealed that He bubbles were formed both in the matrix by RB and SiC interphase by CVD process. Almost all He bubbles were formed at the grain boundary in SiC interphase by CVD process. On the other hand, He bubbles were formed both at the grain boundary and in Si grain of the matrix by RB process. The average size of He bubbles in the matrix by RB was smaller than that in SiC interphase by CVD

{sup 4}He on the outside of a bundle of (10,10) carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Gordillo, M C [Departamento de Sistemas Fisicos, Quimicos y Naturales. Facultad de Ciencias Experimentales, Universidad Pablo de Olavide, Sevilla (Spain)], E-mail: cgorbar@upo.es

2009-02-01

Diffusion Monte Carlo calculations were performed on the subject of {sup 4}He adsorbed on the external surface of (10,10) carbon nanotube bundles. The carbon nanotubes were considered to be defectless and perfectly parallel cylinders in which all individual carbon-helium interactions were considered. This corrugation makes this substrate a very inhomogeneous one, with a range of {sup 4}He binding energies in the infinity dilution limit between {approx} 227 and 202 K. On increasing the helium density, we go from a quasi one-dimensional phase on the grooves between two tubes, to a liquid monolayer, with a three-line arrangement in between. No stable solid helium monolayer at high density was found. Instead, helium atoms are promoted to a second quasi-one dimensional phase on top of the liquid first layer. On increasing the helium intake, a two layer structure is formed in which the helium directly in contact with the carbon surface solidifies.

Devolatilization characteristics of biomass at flash heating rate

Energy Technology Data Exchange (ETDEWEB)

Xiu Shuangning; Li Zhihe; Li Baoming; Yi Weiming; Bai Xueyuan [China Agricultural University, Beijing (China). College of Water Conservancy and Civil Engineering

2006-03-15

The devolatilization characteristics of biomass (wheat straw, coconut shell, rice husk and cotton stalk) during flash pyrolysis has been investigated on a plasma heated laminar entrained flow reactor (PHLEFR) with average heating rates of 10{sup 4} K/s. These experiments were conducted with steady temperatures between 750 and 900 K, and the particle residence time varied from about 0.115 to 0.240 s. The ash tracer method was introduced to calculate the yield of volatile products at a set temperature and the residence time. This experimental study showed that the yield of volatile products depends both on the final pyrolysis temperature and the residence time. From the results, a comparative analysis was done for the biomasses, and a one-step global model was used to simulate the flash pyrolytic process and predict the yield of volatile products during pyrolysis. The corresponding kinetic parameters of the biomasses were also analyzed and determined. These results were essential for designing a suitable pyrolysis reactor. 24 refs., 5 figs., 5 tabs.

r-process nucleosynthesis in dynamic helium-burning environments

International Nuclear Information System (INIS)

Cowan, J.J.; Cameron, A.G.W.; Truran, J.W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning environments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the 13 C neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be: 10 20 --10 21 neutrons cm -3 for times of 0.01--0.1 s and neutron number densities in excess of 10 19 cm -3 for times of approx.1 s. The amount of 13 C required is found to be exceedingly high: larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system

A liquid helium saver

International Nuclear Information System (INIS)

Avenel, O.; Der Nigohossian, G.; Roubeau, P.

1976-01-01

A cryostat equipped with a 'liquid helium saver' is described. A mass flow rate M of helium gas at high pressure is injected in a counter-flow heat exchanger extending from room to liquid helium temperature. After isenthalpic expansion through a calibrated flow impedance this helium gas returns via the low pressure side of the heat exchanger. The helium boil-off of the cryostat represents a mass flow rate m, which provides additional precooling of the incoming helium gas. Two operating regimes appear possible giving nearly the same efficiency: (1) high pressure (20 to 25 atm) and minimum flow (M . L/W approximately = 1.5) which would be used in an open circuit with helium taken from a high pressure cylinder; and (2) low pressure (approximately = 3 atm), high flow (M . L/W > 10) which would be used in a closed circuit with a rubber diaphragm pumping-compressing unit; both provide a minimum theoretical boil-off factor of about 8%. Experimental results are reported. (U.K.)

Economic assessment of flash co-pyrolysis of short rotation coppice and biopolymer waste streams.

Science.gov (United States)

Kuppens, T; Cornelissen, T; Carleer, R; Yperman, J; Schreurs, S; Jans, M; Thewys, T

2010-12-01

The disposal problem associated with phytoextraction of farmland polluted with heavy metals by means of willow requires a biomass conversion technique which meets both ecological and economical needs. Combustion and gasification of willow require special and costly flue gas treatment to avoid re-emission of the metals in the atmosphere, whereas flash pyrolysis mainly results in the production of (almost) metal free bio-oil with a relatively high water content. Flash co-pyrolysis of biomass and waste of biopolymers synergistically improves the characteristics of the pyrolysis process: e.g. reduction of the water content of the bio-oil, more bio-oil and less char production and an increase of the HHV of the oil. This research paper investigates the economic consequences of the synergistic effects of flash co-pyrolysis of 1:1 w/w ratio blends of willow and different biopolymer waste streams via cost-benefit analysis and Monte Carlo simulations taking into account uncertainties. In all cases economic opportunities of flash co-pyrolysis of biomass with biopolymer waste are improved compared to flash pyrolysis of pure willow. Of all the biopolymers under investigation, polyhydroxybutyrate (PHB) is the most promising, followed by Eastar, Biopearls, potato starch, polylactic acid (PLA), corn starch and Solanyl in order of decreasing profits. Taking into account uncertainties, flash co-pyrolysis is expected to be cheaper than composting biopolymer waste streams, except for corn starch. If uncertainty increases, composting also becomes more interesting than flash co-pyrolysis for waste of Solanyl. If the investment expenditure is 15% higher in practice than estimated, the preference for flash co-pyrolysis compared to composting biopolymer waste becomes less clear. Only when the system of green current certificates is dismissed, composting clearly is a much cheaper processing technique for disposing of biopolymer waste. Copyright © 2010 Elsevier Ltd. All rights reserved.

Genetic changes in Mammalian cells transformed by helium cells

Energy Technology Data Exchange (ETDEWEB)

Durante, M.; Grossi, G. (Naples Univ. (Italy). Dipt. di Scienze Fisiche); Yang, T.C.; Roots, R. (Lawrence Berkeley Lab., CA (USA))

1990-11-01

Midterm Syrian Hamster embryo (SHE) cells were employed to study high LET-radiation induced tumorigenesis. Normal SHE cells (secondary passage) were irradiated with accelerated helium ions at an incident energy of 22 MeV/u (9--10 keV/{mu}m). Transformed clones were isolated after growth in soft agar of cells obtained from the foci of the initial monolayer plated postirradiation. To study the progression process of malignant transformation, the transformed clones were followed by monolayer subculturing for prolonged periods of time. Subsequently, neoplasia tests in nude mice were done. In this work, however, we have focused on karyotypic changes in the banding patterns of the chromosomes during the early part of the progressive process of cell transformation for helium ion-induced transformed cells. 26 refs., 5 figs., 2 tabs.

Detection of Malicious Flash Banner Advertisements

Directory of Open Access Journals (Sweden)

Kirill Alekseevich Samosadnyy

2014-09-01

Full Text Available The paper addresses the problem of detecting malicious flash advertisements. As a result, detection method based on dynamic analysis that modify flash application and execute it in Adobe Flash player is proposed and evaluated on synthetic and real world examples.

Depression, quality of life, work productivity, resource use, and costs among women experiencing menopause and hot flashes: a cross-sectional study.

Science.gov (United States)

Dibonaventura, Marco Dacosta; Wagner, Jan-Samuel; Alvir, Jose; Whiteley, Jennifer

2012-01-01

To examine the effect of depression on health-related quality of life, work productivity, resource use, and costs among women experiencing menopausal symptoms, including hot flashes. The study included data from the 2005 US National Health and Wellness Survey (N = 41,184), a cross-sectional, Internet-based survey representative of the adult US population. Among women who reported experiencing menopausal symptoms, including hot flashes, women who reported experiencing depression in the last year (n = 1,165) were compared with women who did not report experiencing depression in the last year (n = 2,467), controlling for demographic and health characteristics. Outcome measures included health-related quality of life (Medical Outcomes Study 8-item Short-Form Health Survey [SF-8]), work productivity within the past 7 days, self-reported health care resource use within the past 6 months, and indirect and direct costs. Women experiencing depression were significantly more likely to be white, to be unemployed, to be uninsured, to currently smoke, to not exercise, and to be obese (all P women experiencing depression reported significantly lower mental (39.66 vs 50.85, P work (5.31% vs 2.80%, P work (25.00% vs 14.32%, P women experiencing depression. The numbers of physician visits (2.47 vs 1.77, P women experiencing depression. Per woman per year indirect and direct costs were $3,066 and $1,075 higher, respectively, for women experiencing depression compared with those not experiencing depression. Approximately one-third of women experiencing menopausal symptoms, including hot flashes, also reported experiencing depression. These women reported significantly worse quality of life and significantly greater work productivity loss, health care resource use, and costs. Given the prevalence and burden, these findings suggest that proper assessment and management of depressive symptoms among women with menopause may have an important humanistic and economic benefit.

Four-body conversion of atomic helium ions

International Nuclear Information System (INIS)

de Vries, C.P.; Oskam, H.J.

1980-01-01

The conversion of atomic helium ions into molecular ions was studied in pure helium and in helium-neon mixtures containing between 0.1 at. % and 50 at. % neon. The experiments showed that the termolecular conversion reaction, He + +2He → He 2 + +He, is augmented by the four-body conversion reaction He + +3He → products, where the products could include either He 2 + or He 3 + ions. Conversion rate coefficients of (5.7 +- 0.8) x 10 -32 cm 6 sec -1 and (2.6 +- 0.4) x 10 -49 cm 9 sec -1 were found for the termolecular and four-body conversion reactions, respectively. In addition, rate coefficients for the following Ne + conversion reactions were measured: Ne + +He+He → (HeNe) + +He, (2.3 +- 0.1) x 10 -32 cm 6 sec -1 ; Ne + +He+Ne → (HeNe) + +Ne or Ne 2 + +He, (8.0 +- 0.8) x 10 -32 cm 6 sec -1 ; and Ne + +Ne+Ne → Ne 2 + +Ne, (5.1 +- 0.3) x 10 -32 cm 6 sec -1 . All rate coefficients are at a gas temperature of 295 K

Overview of the carbon products consortium (CPC)

Energy Technology Data Exchange (ETDEWEB)

Irwin, C.L. [West Virginia Univ., Morgantown, WV (United States)

1996-08-01

The Carbon Products Consortium (CPC) is an industry, university, government cooperative research team which has evolved over the past seven years to produce and evaluate coal-derived feedstocks for carbon products. The members of the Carbon Products Consortium are UCAR Carbon Company, Koppers Industries, CONOCO, Aluminum Company of America, AMOCO Polymers, and West Virginia University. The Carbon and Insulation Materials Technology Group at Oak Ridge National Laboratory, Fiber Materials Inc., and BASF Corporation are affiliates of the CPC. The initial work on coal-derived nuclear graphites was supported by a grant to WVU, UCAR Carbon, and ORNL from the U.S. DOE New Production Reactor program. More recently, the CPC program has been supported through the Fossil Energy Materials program and through PETC`s Liquefaction program. The coal processing technologies involve hydrogenation, extraction by solvents such as N-methyl pyrolidone and toluene, material blending, and calcination. The breadth of carbon science expertise and manufacturing capability available in the CPC enables it to address virtually all research and development issues of importance to the carbon products industry.

Formation of excited states in high-Z helium-like systems

International Nuclear Information System (INIS)

Fritzsche, S.; Fricke, B.; Brinzanescu, O.

1999-12-01

High-Z helium-like ions represent the simplest multi-electron systems for studying the interplay between electron-electron correlations, relativistic as well as quantum electrodynamical effects in strong fields. In contrast to the adjacent lithium-like ions, however, almost no experimental information is available about the excited states in the high-Z domain of the helium sequence. Here, we present a theoretical analysis of the X-ray production and decay dynamics of the excited states in helium-like uranium. Emphasize has been paid particularly to the formation of the 3 P 0 and 3 P 2 levels by using electron capture into hydrogen-like U 91+ . Both states are of interest for precise measurements on high-Z helium-like ions in the future. (orig.)

Bio-oil from Flash Pyrolysis of Agricultural Residues

DEFF Research Database (Denmark)

Ibrahim, Norazana

This thesis describes the production of bio-oils from flash pyrolysis of agricultural residues, using a pyrolysis centrifugal reactor (PCR). By thermal degradation of agricultural residues in the PCR, a liquid oil, char and non-condensable gases are produced. The yield of each fraction...

Helium-cooled nuclear reactor

International Nuclear Information System (INIS)

Longton, P.B.; Cowen, H.C.

1975-01-01

In helium cooled HTR's there is a by-pass circuit for cleaning purposes in addition to the main cooling circuit. This is to remove such impurities as hydrogen, methane, carbon monoxide and water from the coolant. In this system, part of the coolant successively flows first through an oxidation bed of copper oxide and an absorption bed of silica gel, then through activated charcoal or a molecular sieve. The hydrogen and carbon monoxide impurities are absorbed and the dry gas is returned to the main cooling circuit. To lower the hydrogen/water ratio without increasing the hydrogen fraction in the main cooling circuit, some of the hydrogen fraction converted into water is added to the cooling circuit. This is done, inter alia, by bypassing the water produced in the oxidation bed before it enters the absorption bed. The rest of the by-pass circuit, however, also includes an absorption bed with a molecular sieve. This absorbs the oxidized carbon monoxide fraction. In this way, such side effects as the formation of additional methane, carburization of the materials of the by-pass circuit or loss of graphite are avoided. (DG/RF) [de

Modélisation de Fautes et Test des Mémoires Flash

OpenAIRE

Ginez , Olivier

2007-01-01

Flash memories more and more occurs in complex integrated circuits designed for portable electronic devices and dominate the area of such circuits. The lack of defects within these memories is therefore one the key elements of the production yield for manufacturers of these types of applications. However, the high integration density and the complexity of the fabrication process make these Flash memories more and more prone to manufacturing defects. To exhibit the failures that affect the fun...

Diffusion of helium and nucleation-growth of helium-bubbles in metallic materials

International Nuclear Information System (INIS)

Zhang Chonghong; Chen Keqin; Wang Yinshu

2001-01-01

Studies of diffusion and aggregation behaviour of helium in metallic materials are very important to solve the problem of helium embrittlement in structural materials used in the environment of nuclear power. Experimental studies on helium diffusion and aggregation in austenitic stainless steels in a wide temperature range have been performed in authors' research group and the main results obtained are briefly summarized. The mechanism of nucleation-growth of helium-bubbles has been discussed and some problems to be solved are also given

On multiphase negative flash for ideal solutions

DEFF Research Database (Denmark)

Yan, Wei; Stenby, Erling Halfdan

2012-01-01

simpler than the corresponding normal flash algorithm. Unlike normal flash, multiphase negative flash for ideal solutions can diverge if the feasible domain for phase amounts is not closed. This can be judged readily during the iteration process. The algorithm can also be extended to the partial negative......There is a recent interest to solve multiphase negative flash problems where the phase amounts can be negative for normal positive feed composition. Solving such a negative flash problem using successive substitution needs an inner loop for phase distribution calculation at constant fugacity...... coefficients. It is shown that this inner loop, named here as multiphase negative flash for ideal solutions, can be solved either by Michelsen's algorithm for multiphase normal flash, or by its variation which uses F−1 phase amounts as independent variables. In either case, the resulting algorithm is actually...

Measuring hot flash phenomenonology using ambulatory prospective digital diaries

Science.gov (United States)

Fisher, William I.; Thurston, Rebecca C.

2016-01-01

Objective This study provides the description, protocol, and results from a novel prospective ambulatory digital hot flash phenomenon diary. Methods This study included 152 midlife women with daily hot flashes who completed an ambulatory electronic hot flash diary continuously for the waking hours of 3 consecutive days. In this diary, women recorded their hot flashes and accompanying characteristics and associations as the hot flashes occurred. Results Self-reported hot flash severity on the digital diaries indicated that the majority of hot flashes were rated as mild (41.3%) or moderate (43.7%). Severe (13.1%) and very severe (1.8%) hot flashes were less common. Hot flash bother ratings were rated as mild (43%), or moderate (33.5%), with fewer hot flashes reported bothersome (17.5%) or very bothersome (6%). The majority of hot flashes were reported as occurring on the on the face (78.9%), neck (74.7%), and chest (61.3%). Prickly skin was reported concurrently with 32% of hot flashes, 7% with anxiety and 5% with nausea. A novel finding, 38% of hot flashes were accompanied by a premonitory aura. Conclusion A prospective electronic digital hot flash diary allows for a more precise quantitation of hot flashes while overcoming many of the limitations of commonly employed retrospective questionnaires and paper diaries. Unique insights into the phenomenology, loci and associated characteristics of hot flashes were obtained using this device. The digital hot flash phenomenology diary is recommended for future ambulatory studies of hot flashes as a prospective measure of the hot flash experience. PMID:27404030

Laser-induced ion emission during polymer deposition from a flash-frozen water ice matrix

DEFF Research Database (Denmark)

Rodrigo, K.; Toftmann, Bo; Schou, Jørgen

2004-01-01

Flash-frozen water solutions of 1% weight PEG (polyethylene glycol) at -50 degreesC were used as targets at a laser wavelength of 355 nm for polymer deposition with Matrix-Assisted Pulsed Laser Evaporation (MAPLE). For medium laser fluences the transfer of PEG material to the substrate was accomp......Flash-frozen water solutions of 1% weight PEG (polyethylene glycol) at -50 degreesC were used as targets at a laser wavelength of 355 nm for polymer deposition with Matrix-Assisted Pulsed Laser Evaporation (MAPLE). For medium laser fluences the transfer of PEG material to the substrate...

Three-dimensional decomposition models for carbon productivity

International Nuclear Information System (INIS)

Meng, Ming; Niu, Dongxiao

2012-01-01

This paper presents decomposition models for the change in carbon productivity, which is considered a key indicator that reflects the contributions to the control of greenhouse gases. Carbon productivity differential was used to indicate the beginning of decomposition. After integrating the differential equation and designing the Log Mean Divisia Index equations, a three-dimensional absolute decomposition model for carbon productivity was derived. Using this model, the absolute change of carbon productivity was decomposed into a summation of the absolute quantitative influences of each industrial sector, for each influence factor (technological innovation and industrial structure adjustment) in each year. Furthermore, the relative decomposition model was built using a similar process. Finally, these models were applied to demonstrate the decomposition process in China. The decomposition results reveal several important conclusions: (a) technological innovation plays a far more important role than industrial structure adjustment; (b) industry and export trade exhibit great influence; (c) assigning the responsibility for CO 2 emission control to local governments, optimizing the structure of exports, and eliminating backward industrial capacity are highly essential to further increase China's carbon productivity. -- Highlights: ► Using the change of carbon productivity to measure a country's contribution. ► Absolute and relative decomposition models for carbon productivity are built. ► The change is decomposed to the quantitative influence of three-dimension. ► Decomposition results can be used for improving a country's carbon productivity.

Proton and deuteron production in neutron-induced reactions on carbon at En=42.5, 62.7, and 72.8 MeV

International Nuclear Information System (INIS)

Slypen, I.; Corcalciuc, V.; Meulders, J.P.

1995-01-01

Double-differential cross sections for proton and deuteron production in fast neutron induced reactions on carbon are reported for three incident neutron energies: 42.5, 62.7, and 72.8 MeV. Angular distributions were measured at laboratory angles between 20 degree and 160 degree. Procedures for data taking and data reduction are presented. Energy-differential cross sections and total cross sections are also reported. Experimental cross sections are compared with existing data and with theoretical calculations in the frame of the intranuclear cascade model

Adsorption purification of helium coolant of high-temperature gas-cooled reactors of carbon dioxide

International Nuclear Information System (INIS)

Varezhkin, A.V.; Zel'venskij, Ya.D.; Metlik, I.V.; Khrulev, A.A.; Fedoseenkin, A.N.

1986-01-01

A series experiments on adsorption purification of helium of CO 2 using national adsorbent under the conditions characteristic of HTGR type reactors cleanup system is performed. The experimnts have been conducted under the dynamic mode with immobile adsorbent layer (CaA zeolite) at gas flow rates from 0,02 to 0,055 m/s in the pressure range from 0,8 to 5 MPa at the temperature of 273 and 293 K. It is shown that the adsorption grows with the decrease of gas rate, i.e. with increase of contact time with adsorbent. The helium pressure, growth noticeably whereas the temperature decrease from 293 to 273 K results in adsorption 2,6 times increase. The conclusion is drawn that it is advisable drying and purification of helium of CO 2 to perform separately using different zeolites: NaA - for water. CaA - for CO 2 . Estimations of purification unit parameters are realized

Lunar Impact Flash Locations from NASA's Lunar Impact Monitoring Program

Science.gov (United States)

Moser, D. E.; Suggs, R. M.; Kupferschmidt, L.; Feldman, J.

2015-01-01

Meteoroids are small, natural bodies traveling through space, fragments from comets, asteroids, and impact debris from planets. Unlike the Earth, which has an atmosphere that slows, ablates, and disintegrates most meteoroids before they reach the ground, the Moon has little-to-no atmosphere to prevent meteoroids from impacting the lunar surface. Upon impact, the meteoroid's kinetic energy is partitioned into crater excavation, seismic wave production, and the generation of a debris plume. A flash of light associated with the plume is detectable by instruments on Earth. Following the initial observation of a probable Taurid impact flash on the Moon in November 2005,1 the NASA Meteoroid Environment Office (MEO) began a routine monitoring program to observe the Moon for meteoroid impact flashes in early 2006, resulting in the observation of over 330 impacts to date. The main objective of the MEO is to characterize the meteoroid environment for application to spacecraft engineering and operations. The Lunar Impact Monitoring Program provides information about the meteoroid flux in near-Earth space in a size range-tens of grams to a few kilograms-difficult to measure with statistical significance by other means. A bright impact flash detected by the program in March 2013 brought into focus the importance of determining the impact flash location. Prior to this time, the location was estimated to the nearest half-degree by visually comparing the impact imagery to maps of the Moon. Better accuracy was not needed because meteoroid flux calculations did not require high-accuracy impact locations. But such a bright event was thought to have produced a fresh crater detectable from lunar orbit by the NASA spacecraft Lunar Reconnaissance Orbiter (LRO). The idea of linking the observation of an impact flash with its crater was an appealing one, as it would validate NASA photometric calculations and crater scaling laws developed from hypervelocity gun testing. This idea was

Flash pyrolysis fuel oil: BIO-POK

Energy Technology Data Exchange (ETDEWEB)

Gust, S. [Neste Oy, Porvoo (Finland)

1995-12-31

Flash pyrolysis oil from Ensyn Tech., Canada and Union Fenosa, Spain was combusted with simple pressure atomisation equipment commonly used with light fuel oils in intermediate size (0.1-1 MW) boilers. With a number of modifications to the combustion system, carbon monoxide (CO) and nitrous oxide (NO{sub x}) could be reduced to acceptable levels: CO < 30 ppm and NO{sub x} < 140 ppm. Particulate emissions which were initially very high (Bacharach 4-5) were reduced (Bach. 2-3) by system changes but are still higher than from light fuel oil (Bach. <1). The modifications to the combustion system were: acid resistant progressive cavity pump, higher oil preheat temperature and higher oil pressure than for light fuel oils, refractory section between burner and boiler warmed up to at least 800 deg C. In addition, it was necessary to store pyrolysis oil samples under inert conditions to prevent oxidation and to rinse nozzles with alcohol after shutdown to prevent coking. The complexity and cost of these system modifications are considered to be too great for current grades of flash pyrolysis oil to be sold as a light fuel oil replacement. Improvements to fuel quality will be necessary. The main improvements are lowering of viscosity and improving of stability

Flash pyrolysis fuel oil: BIO-POK

Energy Technology Data Exchange (ETDEWEB)

Gust, S [Neste Oy, Porvoo (Finland)

1996-12-31

Flash pyrolysis oil from Ensyn Tech., Canada and Union Fenosa, Spain was combusted with simple pressure atomisation equipment commonly used with light fuel oils in intermediate size (0.1-1 MW) boilers. With a number of modifications to the combustion system, carbon monoxide (CO) and nitrous oxide (NO{sub x}) could be reduced to acceptable levels: CO < 30 ppm and NO{sub x} < 140 ppm. Particulate emissions which were initially very high (Bacharach 4-5) were reduced (Bach. 2-3) by system changes but are still higher than from light fuel oil (Bach. <1). The modifications to the combustion system were: acid resistant progressive cavity pump, higher oil preheat temperature and higher oil pressure than for light fuel oils, refractory section between burner and boiler warmed up to at least 800 deg C. In addition, it was necessary to store pyrolysis oil samples under inert conditions to prevent oxidation and to rinse nozzles with alcohol after shutdown to prevent coking. The complexity and cost of these system modifications are considered to be too great for current grades of flash pyrolysis oil to be sold as a light fuel oil replacement. Improvements to fuel quality will be necessary. The main improvements are lowering of viscosity and improving of stability

Current-induced dynamics in carbon atomic contacts

DEFF Research Database (Denmark)

Lu, Jing Tao; Gunst, Tue; Brandbyge, Mads

2011-01-01

voltage, which can be used to explore current-induced vibrational instabilities due the NC/BP forces. Furthermore, using tight-binding and the Brenner potential we illustrate how Langevin-type molecular-dynamics calculations including the Joule heating effect for the carbon-chain systems can be performed...... be used to explore current-induced dynamics and instabilities. We find instabilities at experimentally relevant bias and gate voltages for the carbon-chain system. © 2011 Lü et al....... carbon chain connecting electrically gated graphene electrodes. This illustrates how the device stability can be predicted solely from the modes obtained from the Langevin equation, including the current-induced forces. We point out that the gate offers control of the current, independent of the bias...

Short and long-term carbon balance of bioenergy electricity production fueled by forest treatments.

Science.gov (United States)

Kelsey, Katharine C; Barnes, Kallie L; Ryan, Michael G; Neff, Jason C

2014-01-01

Forests store large amounts of carbon in forest biomass, and this carbon can be released to the atmosphere following forest disturbance or management. In the western US, forest fuel reduction treatments designed to reduce the risk of high severity wildfire can change forest carbon balance by removing carbon in the form of biomass, and by altering future potential wildfire behavior in the treated stand. Forest treatment carbon balance is further affected by the fate of this biomass removed from the forest, and the occurrence and intensity of a future wildfire in this stand. In this study we investigate the carbon balance of a forest treatment with varying fates of harvested biomass, including use for bioenergy electricity production, and under varying scenarios of future disturbance and regeneration. Bioenergy is a carbon intensive energy source; in our study we find that carbon emissions from bioenergy electricity production are nearly twice that of coal for the same amount of electricity. However, some emissions from bioenergy electricity production are offset by avoided fossil fuel electricity emissions. The carbon benefit achieved by using harvested biomass for bioenergy electricity production may be increased through avoided pyrogenic emissions if the forest treatment can effectively reduce severity. Forest treatments with the use of harvested biomass for electricity generation can reduce carbon emissions to the atmosphere by offsetting fossil fuel electricity generation emissions, and potentially by avoided pyrogenic emissions due to reduced intensity and severity of a future wildfire in the treated stand. However, changes in future wildfire and regeneration regimes may affect forest carbon balance and these climate-induced changes may influence forest carbon balance as much, or more, than bioenergy production.

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

International Nuclear Information System (INIS)

Dethloff, Christian; Gaganidze, Ermile; Svetukhin, Vyacheslav V.; Aktaa, Jarir

2012-01-01

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different 10 B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

Energy Technology Data Exchange (ETDEWEB)

Dethloff, Christian, E-mail: christian.dethloff@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Gaganidze, Ermile [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Svetukhin, Vyacheslav V. [Ulyanovsk State University, Leo Tolstoy Str. 42, 432970 Ulyanovsk (Russian Federation); Aktaa, Jarir [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2012-07-15

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different {sup 10}B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

The mutagenic potential of high flash aromatic naphtha.

Science.gov (United States)

Schreiner, C A; Edwards, D A; McKee, R H; Swanson, M; Wong, Z A; Schmitt, S; Beatty, P

1989-06-01

Catalytic reforming is a refining process that converts naphthenes to aromatics by dehydrogenation to make higher octane gasoline blending components. A portion of this wide boiling range hydrocarbon stream can be separated by distillation and used for other purposes. One such application is a mixture of predominantly 9-carbon aromatic molecules (C9 aromatics, primarily isomers of ethyltoluene and trimethylbenzene), which is removed and used as a solvent--high-flash aromatic naphtha. A program was initiated to assess the toxicological properties of high-flash aromatic naphtha since there may be human exposure through inhalation or external body contact. The current study was conducted partly to assess the potential for mutagenic activity and also to assist in an assessment of carcinogenic potential. The specific tests utilized included the Salmonella/mammalian microsome mutagenicity assay, the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) forward mutation assay in CHO cells, in vitro chromosome aberration and sister chromatid exchange (SCE) assays in CHO cells, and an in vivo chromosome aberration assay in rat bone marrow.

76 FR 40931 - In the Matter of Certain Flash Memory and Products Containing Same; Notice of Commission...

Science.gov (United States)

2011-07-12

... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-685] In the Matter of Certain Flash Memory and... for importation, and the sale within the United States after importation of certain flash memory and... other agreements, written or oral, express or implied, between the parties concerning the subject matter...

Potential applications of high temperature helium

International Nuclear Information System (INIS)

Schleicher, R.W. Jr.; Kennedy, A.J.

1992-09-01

This paper discusses the DOE MHTGR-SC program's recent activity to improve the economics of the MHTGR without sacrificing safety performance and two potential applications of high temperature helium, the MHTGR gas turbine plant and a process heat application for methanol production from coal

Characterization of carbon ion-induced mutations in Arabidopsis thaliana

International Nuclear Information System (INIS)

Shikazono, N.; Suzuki, C.; Kitamura, S.; Watanabe, H.; Tano, S.; Tanaka, A.

2003-01-01

Full text: Irradiation of Arabidopsis thaliana by carbon ions was carried out to investigate the mutational effect of ion particles in higher plants. The averaged mutation rate of carbon ions was 2.0 X 10 -6 / Gy, which was 18-fold higher than that of electrons. PCR analysis of the carbon ion-induced mutants showed that, out of 28 mutant alleles, 14 had point-like mutations within the gene, while 14 contained large structural alterations. In the case of 12 electron-induced mutants, 9 had point-like mutations within the gene, while 3 contained large structural alterations. These results suggest that carbon ions are more likely to induce large structural alterations compared with electrons. Further sequence analysis revealed that most of the point-like mutations induced by carbon ions were short deletions. In the case of rearrangements, DNA strand breaks were found to be rejoined using, if present, short homologous sequences for both types of radiation. After carbon ion-irradiation, small deletions were frequently observed around the breakpoints, whereas duplications of terminal sequence were found after electron-irradiation. These results suggest that non-homologous end joining (NHEJ) pathway operates after plant cells are exposed to both ion particles and electrons but that different mode of rejoining deals with the broken ends produced by each radiation. From the present results, it seems reasonable to assume that carbon ions could predominantly induce null mutations in Arabidopsis. The fact that the molecular nature of carbon ion-induced mutation was different from that of electrons and that the molecular mechanisms of cells to induce mutations appeared to be also different implicates that ion particle is not only valuable as a new mutagen but also useful as a new tool to study repair mechanisms of certain types of DNA damage

Fragmentation of high-energy ionic hydrogen clusters by single collision with helium

International Nuclear Information System (INIS)

Ouaskit, S.; Farizon, B.; Farizon, M.; Gaillard, M.J.; Chevarier, A.; Chevarier, N.; Gerlic, E.; Stern, M.

1994-09-01

Fragmentation of mass-selected 60-keV/amu-H n + induced by single collision with helium has been studied for various cluster sizes n (9, 13,21, 25, and 31). The absolute cross sections of the charged fragments H p + are measured from p equal to n-2. The deduced mass distributions are strongly different from those obtained at lower collision energy (where molecular evaporation is mainly involved) due to a strong production of ionic fragments with a size of p/n -τ , where A is the normalized fragment mass (p/n) and τ an exponent close to 2.6. (authors)

System of ispFlash configuration

International Nuclear Information System (INIS)

Bourrion, Olivier

2003-01-01

The aim of this module is to allow the use of FPGA components instead of EPLD components which for an equivalent or even inferior capacity are more expensive. For instance, the idea is to replace CPLD components having 512 macro-cells by one FPGA spartan II of Xilinx. However, due to the configuration's volatility, one configuration means is needed to put under voltage. A solution appears to be the using of a high capacity Flash memory coupled to a CPLD of small size to comply with the FPGA configuration protocol; also, one has to provide an in situ configuration means for this memory. Obviously, a product having an equivalent functionality already exists, since Xilinx and ALTERA supply PROMs of serial configuration. Unfortunately, they are expensive and a dealer is implied while the FLASH, the small CPLD and the FPGA spartan II are currently available. In conclusion, by using this assembly, which requires a small supplementary surface and a delay of upmost 240 ms (for the largest FPGA 1 Mbit), one obtains a solution cheaper and more performing than an EPLD of high capacity

Carbon monoxide-releasing molecule-3 suppresses Prevotella intermedia lipopolysaccharide-induced production of nitric oxide and interleukin-1β in murine macrophages.

Science.gov (United States)

Choi, Eun-Young; Choe, So-Hui; Hyeon, Jin-Yi; Choi, Jeom-Il; Choi, In Soon; Kim, Sung-Jo

2015-10-05

This study was performed to analyze the effect of carbon monoxide (CO)-releasing molecule-3 (CORM-3) in alleviating the production of proinflammatory mediators in macrophages treated with lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen associated with periodontal disease, and its possible mechanisms of action. LPS was isolated using the hot phenol-water method. Culture supernatants were assayed for nitric oxide (NO) and interleukin-1β (IL-1β). Gene expression was quantified by real-time PCR, and protein expression by immunoblotting. DNA-binding activities of NF-κB subunits were determined using an ELISA-based kit. CORM-3 suppressed the production of inducible NO synthase (iNOS)-derived NO and IL-1β at both gene transcription and translation levels in P. intermedia LPS-activated RAW264.7 cells. CORM-3 enhanced heme oxygenase-1 (HO-1) expression in cells stimulated with P. intermedia LPS, and inhibition of HO-1 activity by SnPP notably reversed the suppressive effect of CORM-3 on LPS-induced production of NO. LPS-induced phosphorylation of p38 and JNK was not affected by CORM-3. CORM-3 did not influence P. intermedia LPS-induced degradation of IκB-α. Instead, nuclear translocation of NF-κB p65 and p50 subunits was blocked by CORM-3 in LPS-treated cells. In addition, CORM-3 reduced LPS-induced p65 and p50 binding to DNA. Besides, CORM-3 significantly suppressed P. intermedia LPS-induced phosphorylation of STAT1. Overall, this study indicates that CORM-3 suppresses the production of NO and IL-1β in P. intermedia LPS-activated murine macrophages via HO-1 induction and inhibition of NF-κB and STAT1 pathways. The modulation of host inflammatory response by CORM-3 would be an attractive therapeutic approach to attenuate the progression of periodontal disease. Copyright © 2015 Elsevier B.V. All rights reserved.

Flashing inception in flowing liquids

International Nuclear Information System (INIS)

Jones, O.C. Jr.

1980-01-01

The inception of net vaporization in flashing flows is examined. It is suggested that the flashing inception can be expressed as two additive effects. One is due to the static decompression which is a function of the initial temperature and also the expansion rate. The other effect which is a function of Reynolds number and flashing index, is due to the turbulent fluctuations of the flowing liquid. It is shown that by taking a three standard deviation band on the turbulent velocity fluctuations, an adequate representation of the inverse mass flux effect on flashing inception for existing data is obtained. The turbulence effects are combined with the correlation of Alamgir and Lienhard to provide predictive methods recommended for the case where both static and convective decompression effects exist

Screw compressor system for industrial-scale helium refrigerators or industrial ammonia screw compressors for helium refrigeration systems; Schraubenkompressor-System fuer Helium-Grosskaelteanlage oder Ammoniak-Schraubenverdichter aus Industrieanwendungen fuer Helium-Kaelteanlagen

Energy Technology Data Exchange (ETDEWEB)

Fredrich, O.; Mosemann, D.; Zaytsev, D. [GEA Grasso GmbH Refrigeration Technology, Berlin (Germany)

2007-07-01

Material characteristics, requirements and measured data of ammonia and helium compression are compared. The compressor lines for industrial ammonia and helium refrigerators are presented, and important characteristics of the compressors are explained. The test stand for performance measurements with helium and ammonia is described, and results are presented. In spite of the different characteristics of the fluids, the compressor-specific efficiencies (supply characteristic, quality characteristic) were found to be largely identical. The values calculated for helium on the basis of NH3 test runs were found to be realistic, which means that the decades of experience with ammonia in industrial applications can be applied to helium compression as well. The design of screw compressor aggregates (skids) in industrial refrigeration is discussed and illustrated by examples. (orig.)

r-process nucleosynthesis in dynamic helium-burning environments

Science.gov (United States)

Cowan, J. J.; Cameron, A. G. W.; Truran, J. W.

1985-01-01

The results of an extended examination of r-process nucleosynthesis in helium-burning enviroments are presented. Using newly calculated nuclear rates, dynamical r-process calculations have been made of thermal runaways in helium cores typical of low-mass stars and in the helium zones of stars undergoing supernova explosions. These calculations show that, for a sufficient flux of neutrons produced by the C-13 neutron source, r-process nuclei in solar proportions can be produced. The conditions required for r-process production are found to be 10 to the 20th-10 to the 21st neutrons per cubic centimeter for times of 0.01-0.1 s and neutron number densities in excess of 10 to the 19th per cubic centimeter for times of about 1 s. The amount of C-13 required is found to be exceedingly high - larger than is found to occur in any current stellar evolutionary model. It is thus unlikely that these helium-burning environments are responsible for producing the bulk of the r-process elements seen in the solar system.

The Chalk River helium jet and skimmer system

International Nuclear Information System (INIS)

Schmeing, H.; Koslowsky, V.; Wightman, M.; Hardy, J.C.; MacDonald, J.A.; Faestermann, T.; Andrews, H.R.; Geiger, J.S.; Graham, R.L.

1976-01-01

A helium jet and skimmer system intended as an interface between a target location at the Chalk River tandem accelerator and the ion source of an on-line separator presently under construction has been developed. The system consists of a target chamber, a 125 cm long capillary, and a one stage skimmer chamber. The designs of the target and skimmer chambers allow one to vary a large number of independent flow and geometrical parameters with accurate reproducibility. Experiments with the β-delayed proton emitter 25 Si (tsub(1/2)=218 ms) produced in the reaction 24 Mg( 3 He,2n) 25 Si show that under optimized conditions about 75% of the reaction products leaving the target are transported to the skimmer. Of those, more than 90% pass through the skimmer orifice, which separates off 97.5% of the transport gas, helium. By introducing an additional helium flow across the skimming orifice the amount of helium separated off the transport jet can be increased to beyond 99.85%, leaving the high throughput of recoils unaffected. (Auth.)

Investigations concerning the applicability of X-ray flash interference and laser technology to shock-induced solidification of organic liquids

International Nuclear Information System (INIS)

Krehl, Peter; Schaaffs, Werner

By a dielectric discharge through a thin layer of liquid a hot plasma is created, which expands very fast and builds up around a compression ring of very highly compressed matter. X-ray flash interferences and laser light are applied to investigate the structure of the compression rings. To perform investigation of the fine structure, an X-ray flash machine was developed which permits to obtain with a single flash in less than 1μs Laue patterns of monocrystals, and Debye-Scherrer patterns of polycrystalline substances. The investigation of the compression rings in diverse substances by laser light resulted that the optical transparency and solidification is different in different regions of the compression ring. Therefore important hints for experiments with X-ray flash interferences were obtained

System analysis for HTTR-GT/H2 plant. Safety analysis of HTTR for coupling helium gas turbine and H2 plant

International Nuclear Information System (INIS)

Sato, Hiroyuki; Yan, Xing L.; Ohashi, Hirofumi

2017-08-01

High Temperature Gas-cooled Reactor (HTGR) is expected to extend the use of nuclear heat to a wider spectrum of industrial applications because of the high temperature heat supply capability and inherently safe characteristics. Japan Atomic Energy Agency initiated a nuclear cogeneration demonstration project with helium gas turbine power generation and thermochemical hydrogen production utilizing the High Temperature engineering Test Reactor (HTTR), the first HTGR in Japan. This study carries out safety evaluation for the HTTR gas turbine hydrogen cogeneration test plant (HTTR-GT/H 2 plant). The evaluation was conducted for the events newly identified corresponding to the coupling of helium gas turbine and hydrogen production plant to the HTTR. The results showed that loss of load event does not have impact on temperature of fuel and reactor coolant pressure boundary. In addition, reactor coolant pressure does not exceed the evaluation criteria. Furthermore, it was shown that reactor operation can be maintained against temperature transients induced by abnormal events in hydrogen production plant. (author)

GeckoFTL: Scalable Flash Translation Techniques For Very Large Flash Devices

DEFF Research Database (Denmark)

Dayan, Niv; Bonnet, Philippe; Idreos, Stratos

2016-01-01

The volume of metadata needed by a flash translation layer (FTL) is proportional to the storage capacity of a flash device. Ideally, this metadata should reside in the device's integrated RAM to enable fast access. However, as flash devices scale to terabytes, the necessary volume of metadata...... thereby harming performance and device lifetime. In this paper, we identify a key component of the metadata called the Page Validity Bitmap (PVB) as the bottleneck. PVB is used by the garbage-collectors of state-of-the-art FTLs to keep track of which physical pages in the device are invalid. PVB...... constitutes 95% of the FTL's RAM-resident metadata, and recovering PVB after power fails takes a significant proportion of the overall recovery time. To solve this problem, we propose a page-associative FTL called GeckoFTL, whose central innovation is replacing PVB with a new data structure called Logarithmic...

An Analysis of Total Lightning Flash Rates Over Florida

Science.gov (United States)

Mazzetti, Thomas O.; Fuelberg, Henry E.

2017-12-01

Although Florida is known as the "Sunshine State", it also contains the greatest lightning flash densities in the United States. Flash density has received considerable attention in the literature, but lightning flash rate has received much less attention. We use data from the Earth Networks Total Lightning Network (ENTLN) to produce a 5 year (2010-2014) set of statistics regarding total flash rates over Florida and adjacent regions. Instead of tracking individual storms, we superimpose a 0.2° × 0.2° grid over the study region and count both cloud-to-ground (CG) and in-cloud (IC) flashes over 5 min intervals. Results show that the distribution of total flash rates is highly skewed toward small values, whereas the greatest rate is 185 flashes min-1. Greatest average annual flash rates ( 3 flashes min-1) are located near Orlando. The southernmost peninsula, North Florida, and the Florida Panhandle exhibit smaller average annual flash rates ( 1.5 flashes min-1). Large flash rates > 100 flashes min-1 can occur during any season, at any time during the 24 h period, and at any location within the domain. However, they are most likely during the afternoon and early evening in East Central Florida during the spring and summer months.

A global flash flood forecasting system

Science.gov (United States)

Baugh, Calum; Pappenberger, Florian; Wetterhall, Fredrik; Hewson, Tim; Zsoter, Ervin

2016-04-01

The sudden and devastating nature of flash flood events means it is imperative to provide early warnings such as those derived from Numerical Weather Prediction (NWP) forecasts. Currently such systems exist on basin, national and continental scales in Europe, North America and Australia but rely on high resolution NWP forecasts or rainfall-radar nowcasting, neither of which have global coverage. To produce global flash flood forecasts this work investigates the possibility of using forecasts from a global NWP system. In particular we: (i) discuss how global NWP can be used for flash flood forecasting and discuss strengths and weaknesses; (ii) demonstrate how a robust evaluation can be performed given the rarity of the event; (iii) highlight the challenges and opportunities in communicating flash flood uncertainty to decision makers; and (iv) explore future developments which would significantly improve global flash flood forecasting. The proposed forecast system uses ensemble surface runoff forecasts from the ECMWF H-TESSEL land surface scheme. A flash flood index is generated using the ERIC (Enhanced Runoff Index based on Climatology) methodology [Raynaud et al., 2014]. This global methodology is applied to a series of flash floods across southern Europe. Results from the system are compared against warnings produced using the higher resolution COSMO-LEPS limited area model. The global system is evaluated by comparing forecasted warning locations against a flash flood database of media reports created in partnership with floodlist.com. To deal with the lack of objectivity in media reports we carefully assess the suitability of different skill scores and apply spatial uncertainty thresholds to the observations. To communicate the uncertainties of the flash flood system output we experiment with a dynamic region-growing algorithm. This automatically clusters regions of similar return period exceedence probabilities, thus presenting the at-risk areas at a spatial

Flash hydropyrolysis of coal using a small scale of free fall reactor

Energy Technology Data Exchange (ETDEWEB)

Miura, K.; Morozumi, F. [Kyoto University, Kyoto (Japan). Department of Chemical Engineering

1998-07-01

A small scale of high-pressure free fall reactor was developed for the flash hydropyrolysis of coal. Taiheiyo coal (a Japanese subbituminous coal) was pyrolysed under a high hydrogen pressure without difficulty by use of this reactor. The effect of gas atmosphere, residence time, pressure, and temperature on the product yield was examined in detail. A flash hydropyrolysis reaction model was developed based on the experimental data, and its validity was examined. 8 refs., 5 figs., 1 tab.

Flash CS4: The Missing Manual

CERN Document Server

Grover, Chris

2008-01-01

Unlock the power of Flash and bring gorgeous animations to life onscreen. Flash CS4: The Missing Manual includes a complete primer on animation, a guided tour of the program's tools and capabilities, lots of new illustrations, and more details on working with video. Beginners will learn to use the software in no time, and experienced Flash designers will improve their skills.

Chromosome aberrations induced by 135 MeV of carbon and neon beams by PRC

International Nuclear Information System (INIS)

Ohara, Hiroshi; Minamihisamatu, Masako; Kanai, Tatsuaki; Eguchi-Kasai, Kiyomi; Itsukaichi, Hiromi; Fukutsu, Kumiko; Yatagai, Fumio; Sato, Kohki.

1993-01-01

Radiation-induced chromosome aberration can be an indicator of the radiation lesions in irradiated cells. Many studies on chromosome aberration induced by X-ray and γ - ray have indicated that the dose response of the aberration can be fitted to a quadratic equation, Y = αD + βD 2 , and it becomes linear as the LET of beams increases. The main subject of this study was some quantification of chromosomal aberration induced by 135 MeV/n carbon and neon beams produced by the RRC, the operation of which increasingly became useful for the studies on heavy ion biology. The results will meet with some of the radiobiological features connected to the specific action of charged particles. The materials used, the experimental method and the results are reported. Four curves of the dose response for the production of dicentric and ring types of aberration induced by carbon and neon beams and four different dose average LETs are given. Aberration production rate became higher as LET increased. Chromosome aberration can be quantified as an indicator of radiation lesions in the case of high LET particle radiation. (K.I.)

Self-trapping of helium in metals

International Nuclear Information System (INIS)

Wilson, W.D.; Bisson, C.L.; Baskes, M.I.

1981-01-01

Atomistic calculations are presented which demonstrate that helium atoms in a metal lattice are able to cluster with each other, producing vacancies and nearby self-interstitial defects. Even a small number of helium atoms is found to be sufficient to create these large distortions. As few as five interstitial helium can spontaneously produce a lattice vacancy and nearby self-interstitial. An eight-helium-atom cluster gives rise to two such defects, and 16 helium atoms to more than five self-interstitial vacancy pairs. It was noted that the self-interstitials prefer to agglomerate on the same ''side'' of the helium cluster rather than to spread themselves out uniformly. The binding energy of each additional helium atom to these clusters increases with helium concentration and the trap is apparently unsaturable. A rate theory using these atomistic binding energies has been used to calculate the kinetics of helium-bubble nucleation and growth. The results are consistent with measurements of the properties of helium resulting from tritium decay

Honeywell optical investigations on FLASH program

Science.gov (United States)

O'Rourke, Ken; Peterson, Eric; Yount, Larry

1995-05-01

The increasing performance and reduction of life cycle cost requirements placed on commercial and military transport aircraft are resulting in more complex, highly integrated aircraft control and management systems. The use of fiber optic data transmission media can make significant contributions in achieving these performance and cost goals. The Honeywell portion of Task 2A on the Fly-by-Light Advanced System Hardware (FLASH) program is evaluating a Primary Flight Control System (PFCS) using pilot and copilot inputs from Active Hand Controllers (AHC) which are optically linked to the primary flight Control Computers (PFCC). Customer involvement is an important element of the Task 2A activity. Establishing customer requirements and perspectives on productization of systems developed under FLASH are key to future product success. The Honeywell elements of the PFCS demonstrator provide a command path that is optically interfaced from crew inputs to commands of distributed, smart actuation subsystems commands. Optical communication architectures are implemented using several protocols including the new AS-1773A 20 Mbps data bus standard. The interconnecting fiber optic cable plant is provided by our Task 1A teammate McDonnell Douglas Aerospace (West). Fiber optic cable plant fabrication uses processed, tools and materials reflecting necessary advances in manufacturing required to make fly-by-light avionics systems marketable.

The assessment of helium purification system of small power HTGR

International Nuclear Information System (INIS)

Siti Alimah; Sriyono

2016-01-01

The helium purification system (HPS) is one of safety system of High Temperature Gas-cooled Reactor. HPS removes impurities in the primary coolant, so that the impact on structure, system and component (SSC) is minimized. The two impurity types are particulates (carbon dust, fission products (Kr, Xe, Cs etc.) and the gases (O_2, N_2, H_2O, CH_4, CO, CO_2 and H_2). Every reactor has a different impurity limit during normal operation, depends on the reactor power, energy conversion system and fuel type. This paper discusses the HPS on HTR-10, HTTR and Indonesian RDE conceptual design. The purpose of this assessment is to determine the optimum HPS design as a role model for Indonesian RDE. The utilized methodology is a literature study based on the operating experiences of both HTR-10 and HTTR as well as the evaluation of RDE conceptual design. This study focuses on the impurities limit during normal operation, the main components of HPS, mass flow-rate and regeneration process. The main component that used in HPS for HTR-10, HTTR and RDE are similar i.e. filter, CuO column, water cooler, molecular sieve bed and cryogenic activated carbon bed. Refer to the HTR-10 and HTTR operational experiences, both of those reactors have a purification systems that capable to maintain the helium purity, even though the impurities limit are different. The HPS of HTTR Japan has a stricter impurities limit that N_2, CH_4, and O_2 should not be contained at all during normal operation and the pre-charcoal trap is used to adsorb the fine dust below 0.1 micron. Both of these parameters can be adopted to the RDE's HPS design to minimize the effect of impurities to SSC. (author)

Image-based Modeling of Biofilm-induced Calcium Carbonate Precipitation

Science.gov (United States)

Connolly, J. M.; Rothman, A.; Jackson, B.; Klapper, I.; Cunningham, A. B.; Gerlach, R.

2013-12-01

Pore scale biological processes in the subsurface environment are important to understand in relation to many engineering applications including environmental contaminant remediation, geologic carbon sequestration, and petroleum production. Specifically, biofilm induced calcium carbonate precipitation has been identified as an attractive option to reduce permeability in a lasting way in the subsurface. This technology may be able to replace typical cement-based grouting in some circumstances; however, pore-scale processes must be better understood for it to be applied in a controlled manor. The work presented will focus on efforts to observe biofilm growth and ureolysis-induced mineral precipitation in micro-fabricated flow cells combined with finite element modelling as a tool to predict local chemical gradients of interest (see figure). We have been able to observe this phenomenon over time using a novel model organism that is able to hydrolyse urea and express a fluorescent protein allowing for non-invasive observation over time with confocal microscopy. The results of this study show the likely existence of a wide range of local saturation indices even in a small (1 cm length scale) experimental system. Interestingly, the locations of high predicted index do not correspond to the locations of higher precipitation density, highlighting the need for further understanding. Figure 1 - A micro-fabricated flow cell containing biofilm-induced calcium carbonate precipitation. (A) Experimental results: Active biofilm is in green and dark circles are calcium carbonate crystals. Note the channeling behavior in the top of the image, leaving a large hydraulically inactive area in the biofilm mass. (B) Finite element model: The prediction of relative saturation of calcium carbonate (as calcite). Fluid enters the system at a low saturation state (blue) but areas of high supersaturation (red) are predicted within the hydraulically inactive area in the biofilm. If only effluent

The EUV Helium Spectrum in the Quiet Sun: A By-Product of Coronal Emission?

Science.gov (United States)

Andretta, Vincenzo; DelZanna, Giulio; Jordan, Stuart D.; Oegerle, William (Technical Monitor)

2002-01-01

In this paper we test one of the mechanisms proposed to explain the intensities and other observed properties of the solar helium spectrum, and in particular of its Extreme-Ultraviolet (EUV) resonance lines. The so-called Photoionisation-Recombination (P-R) mechanism involves photoionisation of helium atoms and ions by EUV coronal radiation, followed by recombination cascades. We present calibrated measurements of EUV flux obtained with the two CDS spectrometers on board SOHO, in quiescent solar regions. We were able to obtain an essentially complete estimate of the total photoionizing flux in the wavelength range below 504 A (the photoionisation threshold for He(I)), as well as simultaneous measurements with the same instruments of the intensities of the strongest EUV helium lines: He(II) lambda304, He(I) lambda584, and He(I) lambda537. We find that there are not enough EUV photons to account for the observed helium line intensities. More specifically, we conclude that He(II) intensities cannot be explained by the P-R mechanism. Our results, however, leave open the possibility that the He(I) spectrum could be formed by the P-R mechanism, with the He(II) lambda304 line as a significant photoionizating source.

Flashing coupled density wave oscillation

International Nuclear Information System (INIS)

Jiang Shengyao; Wu Xinxin; Zhang Youjie

1997-07-01

The experiment was performed on the test loop (HRTL-5), which simulates the geometry and system design of the 5 MW reactor. The phenomenon and mechanism of different kinds of two-phase flow instabilities, namely geyser instability, flashing instability and flashing coupled density wave instability are described. The especially interpreted flashing coupled density wave instability has never been studied well, it is analyzed by using a one-dimensional non-thermo equilibrium two-phase flow drift model computer code. Calculations are in good agreement with the experiment results. (5 refs.,5 figs., 1 tab.)

Accumulation and detoxication responses of the gastropod Lymnaea stagnalis to single and combined exposures to natural (cyanobacteria) and anthropogenic (the herbicide RoundUp(®) Flash) stressors.

Science.gov (United States)

Lance, Emilie; Desprat, Julia; Holbech, Bente Frost; Gérard, Claudia; Bormans, Myriam; Lawton, Linda A; Edwards, Christine; Wiegand, Claudia

2016-08-01

Freshwater gastropods are increasingly exposed to multiple stressors in the field such as the herbicide glyphosate in Roundup formulations and cyanobacterial blooms either producing or not producing microcystins (MCs), potentially leading to interacting effects. Here, the responses of Lymnaea stagnalis to a 21-day exposure to non-MC or MC-producing (33μgL(-1)) Planktothrix agardhii alone or in combination with the commercial formulation RoundUp(®) Flash at a concentration of 1μgL(-1) glyphosate, followed by 14days of depuration, were studied via i) accumulation of free and bound MCs in tissues, and ii) activities of anti-oxidant (catalase CAT) and biotransformation (glutathione-S-transferase GST) enzymes. During the intoxication, the cyanobacterial exposure induced an early increase of CAT activity, independently of the MC content, probably related to the production of secondary cyanobacterial metabolites. The GST activity was induced by RoundUp(®) Flash alone or in combination with non MC-producing cyanobacteria, but was inhibited by MC-producing cyanobacteria with or without RoundUp(®) Flash. Moreover, MC accumulation in L. stagnalis was 3.2 times increased when snails were concomitantly exposed to MC-producing cyanobacteria with RoundUp(®), suggesting interacting effects of MCs on biotransformation processes. The potent inhibition of detoxication systems by MCs and RoundUp(®) Flash was reversible during the depuration, during which CAT and GST activities were significantly higher in snails previously exposed to MC-producing cyanobacteria with or without RoundUp(®) Flash than in other conditions, probably related to the oxidative stress caused by accumulated MCs remaining in tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Modular helium reactor for non-electric applications

International Nuclear Information System (INIS)

Shenoy, A.

1997-01-01

The high temperature gas-cooled Modular Helium Reactor (MHR) is an advanced, high efficiency reactor system which can play a vital role in meeting the future energy needs of the world by contributing not only to the generation of electric power, but also the non-electric energy traditionally served by fossil fuels. This paper summarizes work done over 20 years, by several people at General Atomics, how the Modular Helium Reactor can be integrated to provide different non-electric applications during Process Steam/Cogeneration for industrial application, Process Heat for transportation fuel development and Hydrogen Production for various energy applications. The MHR integrates favorably into present petrochemical and primary metal process industries, heavy oil recovery, and future shale oil recovery and synfuel processes. The technical fit of the Process Steam/Cogeneration Modular Helium Reactor (PS/C-MHR) into these processes is excellent, since it can supply the required quantity and high quality of steam without fossil superheating. 12 refs, 25 figs, 2 tabs

Flash CS5 The Missing Manual

CERN Document Server

Grover, Chris

2010-01-01

Once you know how to use Flash, you can create everything from simple animations to high-end desktop applications, but it's a complex tool that can be difficult to master on your own-unless you have this Missing Manual. This book will help you learn all you need to know about Flash CS5 to create animations that bring your ideas to life. Learn animation basics. Find everything you need to know to get started with FlashMaster the Flash tools. Learn the animation and effects toolset, with clear explanations and hands-on examplesUse 3D effects. Rotate and put objects in motion in three dimensions

Accounting for forest carbon pool dynamics in product carbon footprints: Challenges and opportunities

International Nuclear Information System (INIS)

Newell, Joshua P.; Vos, Robert O.

2012-01-01

Modification and loss of forests due to natural and anthropogenic disturbance contribute an estimated 20% of annual greenhouse gas (GHG) emissions worldwide. Although forest carbon pool modeling rarely suggests a ‘carbon neutral’ flux profile, the life cycle assessment community and associated product carbon footprint protocols have struggled to account for the GHG emissions associated with forestry, specifically, and land use generally. Principally, this is due to underdeveloped linkages between life cycle inventory (LCI) modeling for wood and forest carbon modeling for a full range of forest types and harvest practices, as well as a lack of transparency in globalized forest supply chains. In this paper, through a comparative study of U.S. and Chinese coated freesheet paper, we develop the initial foundations for a methodology that rescales IPCC methods from the national to the product level, with reference to the approaches in three international product carbon footprint protocols. Due to differences in geographic origin of the wood fiber, the results for two scenarios are highly divergent. This suggests that both wood LCI models and the protocols need further development to capture the range of spatial and temporal dimensions for supply chains (and the associated land use change and modification) for specific product systems. The paper concludes by outlining opportunities to measure and reduce uncertainty in accounting for net emissions of biogenic carbon from forestland, where timber is harvested for consumer products. - Highlights: ► Typical life cycle assessment practice for consumer products often excludes significant land use change emissions when estimating carbon footprints. ► The article provides a methodology to rescale IPCC guidelines for product-level carbon footprints. ► Life cycle inventories and product carbon footprint protocols need more comprehensive land use-related accounting. ► Interdisciplinary collaboration linking the LCA and

PRESTO: online calculation of carbon in harvested wood products

Science.gov (United States)

Coeli M. Hoover; Sarah J. Beukema; Donald C.E. Robinson; Katherine M. Kellock; Diana A. Abraham

2014-01-01

Carbon stored in harvested wood products is recognized under international carbon accounting protocols, and some crediting systems may permit the inclusion of harvested wood products when calculating carbon sequestration. For managers and landowners, however, estimating carbon stored in harvested wood products may be difficult. PRESTO (PRoduct EStimation Tool Online)...

Particle control in DIII-D with helium glow discharge conditioning

International Nuclear Information System (INIS)

Jackson, G.L.; Taylor, T.S.; Taylor, P.L.

1990-01-01

Helium glow discharge conditioning of DIII-D is routinely used before every tokamak discharge to desorb hydrogen from the graphite tiles, which are the plasma facing surfaces for the floor, inner wall and top of the vessel. In addition to reducing hydrogen fuelling of the plasma by the graphite surfaces, helium glow discharges are also effective in removing low-Z impurities, primarily in the form of carbon monoxide and hydrocarbons, and this has permitted higher current divertor operation and more rapid recovery from tokamak disruptions. Since the implementation of repetitive helium glow wall conditioning, the parameter space in which tokamak discharges in DIII-D can be obtained has been expanded to include the first observations of limiter H-mode confinement, the Ohmic H-mode with periods of up to 150 ms that are free of edge localized modes, more reliable low q operation with volume averaged beta of up to 9.3%, improved control over locked modes and plasma discharges at lower electron density. (author). 37 refs, 12 figs, 1 tab

A Durable Flash Memory Search Tree

OpenAIRE

Clay III, James; Wortman, Kevin

2012-01-01

We consider the task of optimizing the B-tree data structure, used extensively in operating systems and databases, for sustainable usage on multi-level flash memory. Empirical evidence shows that this new flash memory tree, or FM Tree, extends the operational lifespan of each block of flash memory by a factor of roughly 27 to 70 times, while still supporting logarithmic-time search tree operations.

Influence of MHD effects and edge conditions on ITER helium ash accumulation and sustained ignition

International Nuclear Information System (INIS)

Redi, M.H.; Cohen, S.A.

1990-06-01

Dilution of reacting species by build-up of helium ash and its effect on ignition in the ITER tokamak have been studies in a series of simulations with the one-dimensional BALDUR transport code. Thermal diffusivities, obtained from ITER scaling laws and with radial variations observed in JET, gave τ E ∼ 2--4 sec. Refueling of deuterium and tritium maintained constant electron density, while carbon recycling was 100% and the helium ash recycling was varied from 1.0 to 0.5. Including MHD effects, specifically sawteeth and beta limits, we find that ignition can be sustained for 200 seconds with R helium = 0.95. These simulations, the only non-zero-dimensional, time-dependent simulations thus far made for ITER plasmas, emphasize that edge plasma conditions, MHD behavior, and helium particle transport are critical synergistic issues for sustained ignition. 27 refs., 2 figs., 1 tab

Lung injury induced by secondhand smoke exposure detected with hyperpolarized helium-3 diffusion MR.

Science.gov (United States)

Wang, Chengbo; Mugler, John P; de Lange, Eduard E; Patrie, James T; Mata, Jaime F; Altes, Talissa A

2014-01-01

To determine whether helium-3 diffusion MR can detect the changes in the lungs of healthy nonsmoking individuals who were regularly exposed to secondhand smoke. Three groups were studied (age: 59 ± 9 years): 23 smokers, 37 exposure-to-secondhand-smoke subjects, and 29 control subjects. We measured helium-3 diffusion values at diffusion times from 0.23 to 1.97 s. One-way analysis of variance revealed that the mean area under the helium-3 diffusion curves (ADC AUC) of the smokers was significantly elevated compared with the controls and to the exposure-to-secondhand-smoke subjects (P exposure-to-secondhand-smoke subjects and that of the controls was found (P = 0.115). However, application of a receiver operator characteristic-derived rule to classify subjects as either a "control" or a "smoker," based on ADC AUC, revealed that 30% (11/37) of the exposure-to-secondhand subjects were classified as "smokers" indicating an elevation of the ADC AUC. Using helium-3 diffusion MR, elevated ADC values were detected in 30% of nonsmoking healthy subjects who had been regularly exposed to secondhand smoke, supporting the concept that, in susceptible individuals, secondhand smoke causes mild lung damage. Copyright © 2013 Wiley Periodicals, Inc.

Mechanisms of oxidation of alloy 617 in helium-carbon monoxide-carbon dioxide environment with varying carbon and oxygen potentials

Science.gov (United States)

Kumar, Deepak

The objective of this research was to determine the mechanism of decarburization and carburization of the alloy 617 by determining the gas-metal reactions. Binary gas mixtures containing only CO and CO2 as impurities were chosen to circumvent the complications caused by impurities H2, H2O, and CH4, normally, present in helium in addition to CO and CO2; and oxidation tests were conducted between 850°C-1000°C in six environments with CO/CO2 ratio varying between 9 and 1272. A critical temperature corresponding to the equilibrium of the reaction 2Cr+3CO↔Cr2O3+3Csolut ion was identified. Below the critical temperature the alloy reacted with CO resulting in formation of a stable chromia film and carburization, whereas, above the critical temperature the decarburization of the alloy occurred via reaction between the chromia film and carbon in the alloy producing CO and Cr. In environment with CO/CO2 of 9 the critical temperature was between 900°C and 950°C, whereas, in environment with CO/CO 2 ratio higher than 150, it was greater than 1000°C. The decarburization of the alloy occurred via two reactions occurring simultaneously on the surface: 2Cr+3/2O2→Cr2 O3, Cr2O3+3Csolution→ 2Cr+3CO. At 1000°C, the rate liming step was the formation of chromia which prevented the growth of chromia film until the carbon in the sample was depleted. The time taken for this to occur was 300h. The carburization of the alloy resulted in the formation of mixed Cr 2O3 and Cr7C3 surface scale. The Cr 7C3 was a metastable phase which nucleated due to preferential adsorption of carbon on the chromia surface. The Cr7C3 precipitates coarsened at the gas/scale interface via outward diffusion of Cr cations through the chromia scale until the activity of Cr at the reaction site fell below a critical value. Decrease in activity of Cr at the carbide/chromia interface triggered a reaction between chromia and carbide: Cr2O3+Cr7C3 →9Cr+3CO. The CO so produced was transported through the

Multiphysics model of thermomechanical and helium-induced damage of tungsten during plasma heat transients

Energy Technology Data Exchange (ETDEWEB)

Crosby, Tamer, E-mail: tcrosby@ucla.edu; Ghoniem, Nasr M., E-mail: ghoniem@ucla.edu

2013-11-15

A combination of transient heating and bombardment by helium and hydrogen atoms has been experimentally proven to lead to severe surface and sub-surface damage. We developed a computational model to determine the relationship between the thermomechanical loading conditions and the onset of damage and failure of tungsten surfaces. The model is based on a thermoelasticity fracture damage approach that was developed using the phase field method. The model simulates the distribution of helium bubbles inside the grains and on grain boundaries using space-dependent rate theory. In addition, the model is coupled with a transient heat conduction analysis for temperature distributions inside the material. The results show the effects of helium bubbles on reducing tungsten surface energy. Further, a temperature gradient in the material equals to 10 K/μm, resulted in deep cracks propagating from the tungsten surface.

Friendly fermions of helium-three

International Nuclear Information System (INIS)

Leggatt, T.

1976-01-01

The importance of helium in showing up the effects of atomic indistinguishability and as a material by which to test some of the most fundamental principles of quantum mechanics is discussed. Helium not only remains liquid down to zero temperature but of the two isotopes helium-three has intrinsic spin 1/2 and should therefore obey the Pauli principle, while helium-four has spin zero and is expected to undergo Bose condensation. Helium-three becomes superfluid at temperatures of a few thousandths of a degree above absolute zero by the bulk liquid collecting its atoms into spinning pairs. There are three different superfluid phases, now conveniently called A, B and A 1 and each is characterised by a different behaviour of the spin and/or relative angular motion of the atoms composing the Cooper pairs. Problems surrounding the complicated physical system of helium-three are discussed. It is suggested that the combined coherence and directionality of superfluid helium-three should create some fascinating physics. (U.K.)

Research of coal flash hydropyrolysis

Energy Technology Data Exchange (ETDEWEB)

Zhu, Z.; Zhu, H.; Wu, Y.; Tang, L.; Cheng, L.; Xu, Z. [East China University of Science and Technology, Shanghai (China)

2001-02-01

Using x-ray photoelectron spectroscopy (XPS) analyses the organic sufur of seven different Chinese coals and their semi-cokes from flash hydropyrolysis were studied. The results showed that the organic sulfur in coal was alkyal sulfur and thiophene with the peak of XPS located in 163.1-163.5 eV and 164.1-164.5 eV. The relative thiophene content in coal increased with the coal rank. The type of organic sulfur in semi-coke in flash hydropyrolysis was generally thiophene species; its XPS peak also located in 164.1-164.5 eV, and was in accord with its corresponding coal. Total alkyl sulfur and some thiophene sulfur were removed during the flash hydropyrolysis process. The alkyl sulfur had very high activity in hydrogenation reaction. Flash hydropyrolysis was an important new clean-coal technique and had notable desulfurization effect. 13 refs., 2 figs., 4 tabs.

LOFA analyses for the water and helium cooled SEAFP reactors

International Nuclear Information System (INIS)

Sponton, L.; Sjoeberg, A.; Nordlinder, S.

2001-01-01

This study was performed in the frame of the European long-term fusion safety programme 1999 (SEAFP99). Loss of flow accidents (LOFA) have been studied for two cases, first for a helium cooled reactor with advanced dual-coolant (DUAL) blanket at 100% nominal power. The second case applies to a water-cooled reactor at 20% nominal power. Both transients were simulated with the code MELCOR 1.8.4. The results for the helium cooled reactor show that with a natural circulation flow of helium after the pump stops, the first wall temperature will stay below the temperature for excepted failure of the construction material. For the water cooled reactor, the results show that the pressurizer set point for its liquid volumetric inventory is reached before the plasma facing components attain a critical temperature. The pressurizer set point will induce a plasma shutdown

Low-cycle fatigue of heat-resistant alloys in high-temperature gas-cooled reactor helium

International Nuclear Information System (INIS)

Tsuji, H.; Kondo, T.

1984-01-01

Strain controlled low-cycle fatigue tests were conducted on four nickel-base heat-resistant alloys at 900 0 C in simulated high-temperature gas-cooled reactor (HTGR) environments and high vacuums of about 10 -6 Pa. The observed behaviors of the materials were different and divided into two groups when tests were made in simulated HTGR helium, while all materials behaved similarly in vacuums. The materials that have relatively high ductility and compatibility with impure helium at test temperature showed considerable resistance to the fatigue damage in impure helium. On the other hand, the alloys qualified with their high creep strength were seen to suffer from the adverse effects of impure helium and the trend of intergranular cracking as well. The results were analyzed in terms of their susceptibility to the environmentenhanced fatigue damage by examining the ratios of the performance in impure helium to in vacuum. The materials that showed rather unsatisfactory resistance were considered to be characterized by their limited ductility partly due to their coarse grain structure and susceptibility to intergranular oxidation. Moderate carburization was commonly noted in all materials, particularly at the cracked portions, indicating that carbon intrusion had occurred during the crack growth stage

State of the Art Report for a Bearing for VHTR Helium Circulator

International Nuclear Information System (INIS)

Lee, Jae Seon; Song, Kee Nam; Kim, Yong Wan; Lee, Won Jae

2008-10-01

A helium circulator in a VHTR(Very High Temperature gas-cooled Reactor) plays a core role which translates thermal energy at high temperature from a nuclear core to a steam generator. Helium as a operating coolant circulates a primary circuit in high temperature and high pressure state, and controls thermal output of a nuclear core by controlling flow rate. A helium circulator is the only rotating machinery in a VHTR, and its reliability should be guaranteed for reliable operation of a reactor and stable production of hydrogen. Generally a main helium circulator is installed on the top of a steam generator vessel, and helium is circulated only by a main helium circulator in a normal operation state. An auxiliary or shutdown circulator is installed at the bottom of a reactor vessel, and it is an auxiliary circulator for shutting down a reactor in case of refueling or accelerating cooling down in case of fast cooling. Since a rotating shaft of a helium circulator is supported by bearings, bearings are the important machine elements which determines reliability of a helium circulator and a nuclear reactor. Various types of support bearings have been developed and applied for circulator bearings since 1960s, and it is still developing for developing VHTRs. So it is necessary to review and analyze the current technical state of helium circulator support bearings to develop bearings for Koran developing VHTR helium circulator

Helium effects on tungsten surface morphology and deuterium retention

NARCIS (Netherlands)

Ueda, Y.; H. Y. Peng,; H. T. Lee,; N. Ohno,; S. Kajita,; Yoshida, N.; Doerner, R.; De Temmerman, G.; V. Alimov,; G. Wright,

2013-01-01

Recent experimental results on tungsten surface morphology, especially nano-structure (fuzz), induced by helium plasma exposure at temperatures between 1000 K and 2000 K are reviewed. This structure was firstly reported in 2006. In this review, most of experimental results reported

Dislocation Motion and the Microphysics of Flash Heating and Weakening of Faults during Earthquakes

Directory of Open Access Journals (Sweden)

Elena Spagnuolo

2016-07-01

Full Text Available Earthquakes are the result of slip along faults and are due to the decrease of rock frictional strength (dynamic weakening with increasing slip and slip rate. Friction experiments simulating the abrupt accelerations (>>10 m/s2, slip rates (~1 m/s, and normal stresses (>>10 MPa expected at the passage of the earthquake rupture along the front of fault patches, measured large fault dynamic weakening for slip rates larger than a critical velocity of 0.01–0.1 m/s. The dynamic weakening corresponds to a decrease of the friction coefficient (defined as the ratio of shear stress vs. normal stress up to 40%–50% after few millimetres of slip (flash weakening, almost independently of rock type. The microstructural evolution of the sliding interfaces with slip may yield hints on the microphysical processes responsible for flash weakening. At the microscopic scale, the frictional strength results from the interaction of micro- to nano-scale surface irregularities (asperities which deform during fault sliding. During flash weakening, the visco-plastic and brittle work on the asperities results in abrupt frictional heating (flash heating and grain size reduction associated with mechano-chemical reactions (e.g., decarbonation in CO2-bearing minerals such as calcite and dolomite; dehydration in water-bearing minerals such as clays, serpentine, etc. and phase transitions (e.g., flash melting in silicate-bearing rocks. However, flash weakening is also associated with grain size reduction down to the nanoscale. Using focused ion beam scanning and transmission electron microscopy, we studied the micro-physical mechanisms associated with flash heating and nanograin formation in carbonate-bearing fault rocks. Experiments were conducted on pre-cut Carrara marble (99.9% calcite cylinders using a rotary shear apparatus at conditions relevant to seismic rupture propagation. Flash heating and weakening in calcite-bearing rocks is associated with a shock-like stress

Cathode deposits in fullerene formation — microstructural evidence for independent pathways of pyrolytic carbon and nanobody formation

Science.gov (United States)

Taylor, G. H.; Gerald, J. D. Fitz; Pang, L.; Wilson, M. A.

1994-01-01

Microstructures in cathode deposits formed during fullerene production by electrical arcing in helium have been examined in detail. This has provided new information about the mechanisms by which nanobodies (nanotubes and nanoparticles) and pyrolytic carbon are deposited. Nanobodies and pyrolytic carbon form independently; the former probably grow in the plasma then deposit on the electrode but much of the latter deposits directly on the electrode surface.

Safety in handling helium and nitrogen

International Nuclear Information System (INIS)

Schmauch, G.; Lansing, L.; Santay, T.; Nahmias, D.

1991-01-01

Based upon the authors' industrial experience and practices, they have provided an overview of safety in storage, handling, and transfer of both laboratory and bulk quantities of gaseous and liquid forms of nitrogen and helium. They have addressed the properties and characteristics of both the gaseous and liquid fluids, typical storage and transport containers, transfer techniques, and the associated hazards which include low temperatures, high pressures, and asphyxiation. Methods and procedures to control and eliminate these hazards are described, as well as risk remediation through safety awareness training, personal protective equipment, area ventilation, and atmosphere monitoring. They have included as an example a recent process hazards analysis performed by Air Products on the asphyxiation hazard associated with the use of liquid helium in MRI magnet systems

Helium turbo-expander with an alternator

International Nuclear Information System (INIS)

Akiyama, Yoshitane

1980-01-01

Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

Simulating Terrestrial Gamma Ray Flashes due to cosmic ray shower electrons and positrons

Science.gov (United States)

Connell, Paul

2017-04-01

The University of Valencia has developed a software simulator LEPTRACK to simulate the relativistic runaway electron avalanches, RREA, that are presumed to be the cause of Terrestrial Gamma Ray Flashes and their powerful accompanying Ionization/Excitation Flashes. We show here results of LEPTRACK simulations of RREA by the interaction of MeV energy electrons/positrons and photons in cosmic ray showers traversing plausible electric field geometries expected in storm clouds. The input beams of MeV shower products were created using the CORSIKA software package from the Karlsruhe Institute of Technology. We present images, videos and plots showing the different Ionization, Excitation and gamma-ray photon density fields produced, along with their time and spatial profile evolution, which depend critically on where the line of shower particles intercept the electric field geometry. We also show a new effect of incoming positrons in the shower, which make up a significant fraction of shower products, in particular their apparent "orbiting" within a high altitude negative induced shielding charge layer, which has been conjectured to produce a signature microwave emission, as well as a short range 511 keV annihilation line. The interesting question posed is if this conjectured positron emission can be observed and correlated with TGF orbital observations to show if a TGF originates in the macro E-fields of storm clouds or the micro E-fields of lightning leaders where this positron "orbiting" is not likely to occur.

Martensitic transformations in 304 stainless steel after implantation with helium, hydrogen and deuterium

International Nuclear Information System (INIS)

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

1988-01-01

Using conversion electron Moessbauer spectroscopy (CEMS) and glancing angle X-ray diffraction, martensitic transformations have been studied in type 304 austenitic stainless steels implanted with 8 keV helium, hydrogen and deuterium. Furthermore, using CEMS in the energy selective mode (DCEMS), the distribution of martensite in the implantation zone has been analysed as a function of depth. Transformation of the implanted layer occurs after implantation with 10 21 m -2 He + ions while 100 times higher fluence is required for the implanted layer to transform after hydrogen or deuterium implantations. This difference is due to the ability of helium to form high pressure gas bubbles, while implanted hydrogen is continuously lost by back diffusion to the surface. The helium bubbles, which are confined under pressures as high as 60 GPa, will induce extremely high stress levels in the implanted layer, by which the martensitic transformation is directly induced. The fact that a much higher fluence of hydrogen or deuterium is required to induce the transformation, shows that radiation damage plays only a minor role. In this case, the martensitic transformation first occurs when the implanted layer resembles the state of a cathodically charged surface. (orig.)

Suicidal asphyxiation by using helium – two case reports

Directory of Open Access Journals (Sweden)

Anna Smędra

2015-05-01

Full Text Available Helium is one of inert gases causing physical asphyxiation, whose excess content in the breathing atmosphere reduces the partial pressure of oxygen and may be fatal after short-term exposure. When breathing a mixture of an inert gas (helium, nitrogen, argon with a small amount of oxygen, with the possibility of exhaling carbon dioxide, no warning signs characteristic of suffocation are perceived by the subject. Freedom from discomfort and pain, effectiveness, rapid effect and relatively easy availability of required accessories have resulted in the use of inert gases for suicidal purposes. The paper reports two cases of suicide committed by using a special kit consisting of the so-called “suicide bag” (or “exit bag” filled with helium supplied through a plastic tube. In both cases, examination of the sites where the corpses were found and analysis of collected material allowed to establish that before their death the subjects had searched the Internet for instructions on how to commit suicide using helium. Due to the advanced putrefaction process, the autopsies failed to determine the causes of their death unequivocally. However, the circumstances surrounding the deaths suggested rapid asphyxiation as a result of oxygen deficiency in the breathing mixture. Since in cases of the type discussed here the cause of death cannot generally be established by autopsy, knowledge of the circumstances of disclosure of the corpse, as well as examination of the cadaver and the death scene is of utmost importance.

Bipolar cloud-to-ground lightning flash observations

Science.gov (United States)

Saba, Marcelo M. F.; Schumann, Carina; Warner, Tom A.; Helsdon, John H.; Schulz, Wolfgang; Orville, Richard E.

2013-10-01

lightning is usually defined as a lightning flash where the current waveform exhibits a polarity reversal. There are very few reported cases of cloud-to-ground (CG) bipolar flashes using only one channel in the literature. Reports on this type of bipolar flashes are not common due to the fact that in order to confirm that currents of both polarities follow the same channel to the ground, one necessarily needs video records. This study presents five clear observations of single-channel bipolar CG flashes. High-speed video and electric field measurement observations are used and analyzed. Based on the video images obtained and based on previous observations of positive CG flashes with high-speed cameras, we suggest that positive leader branches which do not participate in the initial return stroke of a positive cloud-to-ground flash later generate recoil leaders whose negative ends, upon reaching the branch point, traverse the return stroke channel path to the ground resulting in a subsequent return stroke of opposite polarity.

Weld repair of helium degraded reactor vessel material

International Nuclear Information System (INIS)

Kanne, W.R. Jr.; Lohmeier, D.A.; Louthan, M.R. Jr.; Rankin, D.T.; Franco-Ferreira, E.A.; Bruck, G.J.; Madeyski, A.; Shogan, R.P.; Lessmann, G.G.

1990-01-01

Welding methods for modification or repair of irradiated nuclear reactor vessels are being evaluated at the Savannah River Site. A low-penetration weld overlay technique has been developed to minimize the adverse effects of irradiation induced helium on the weldability of metals and alloys. This technique was successfully applied to Type 304 stainless steel test plates that contained 3 to 220 appm helium from tritium decay. Conventional welding practices caused significant cracking and degradation in the test plates. Optical microscopy of weld surfaces and cross sections showed that large surface toe cracks formed around conventional welds in the test plates but did not form around overlay welds. Scattered incipient underbead cracks (grain boundary separations) were associated with both conventional and overlay test welds. Tensile and bend tests were used to assess the effect of base metal helium content on the mechanical integrity of the low-penetration overlay welds. The axis of tensile specimens was perpendicular to the weld-base metal interface. Tensile specimens were machined after studs were resistance welded to overlay surfaces

Suzaku Reveals Helium-burning Products in the X-Ray-emitting Planetary Nebula BD +30 3639

Science.gov (United States)

Murashima, M.; Kokubun, M.; Makishima, K.; Kotoku, J.; Murakami, H.; Matsushita, K.; Hayashida, K.; Arnaud, K.; Hamaguchi, K.; Matsumoto, H.

2006-08-01

BD +30 3639, the brightest planetary nebula at X-ray energies, was observed with Suzaku, an X-ray observatory launched on 2005 July 10. Using the X-ray Imaging Spectrometer, the K lines from C VI, O VII, and O VIII were resolved for the first time, and the C/O, N/O, and Ne/O abundance ratios were determined. The C/O and Ne/O abundance ratios exceed the solar value by factors of at least 30 and 5, respectively. These results indicate that the X-rays are emitted mainly by helium-shell-burning products.

Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

Energy Technology Data Exchange (ETDEWEB)

Kia, Kaveh Kazemi [Department of Electrical and Computer Engineering, Islamic Azad University of Bonab, Bonab (Iran, Islamic Republic of); Bonabi, Fahimeh [Department of Engineering, Islamic Azad University of Bonab, Bonab (Iran, Islamic Republic of)

2012-12-15

A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 {mu}s. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: circuitry and mechanical design.

Science.gov (United States)

Kia, Kaveh Kazemi; Bonabi, Fahimeh

2012-12-01

A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

Assessment of Embrittlement of VHTR Structural Alloys in Impure Helium Environments

Energy Technology Data Exchange (ETDEWEB)

Crone, Wendy; Cao, Guoping; Sridhara, Kumar

2013-05-31

The helium coolant in high-temperature reactors inevitably contains low levels of impurities during steady-state operation, primarily consisting of small amounts of H{sub 2}, H{sub 2}O, CH{sub 4}, CO, CO{sub 2}, and N{sub 2} from a variety of sources in the reactor circuit. These impurities are problematic because they can cause significant long-term corrosion in the structural alloys used in the heat exchangers at elevated temperatures. Currently, the primary candidate materials for intermediate heat exchangers are Alloy 617, Haynes 230, Alloy 800H, and Hastelloy X. This project will evaluate the role of impurities in helium coolant on the stress-assisted grain boundary oxidation and creep crack growth in candidate alloys at elevated temperatures. The project team will: • Evaluate stress-assisted grain boundary oxidation and creep crack initiation and crack growth in the temperature range of 500-850°C in a prototypical helium environment. • Evaluate the effects of oxygen partial pressure on stress-assisted grain boundary oxidation and creep crack growth in impure helium at 500°C, 700°C, and 850°C respectively. • Characterize the microstructure of candidate alloys after long-term exposure to an impure helium environment in order to understand the correlation between stress-assisted grain boundary oxidation, creep crack growth, material composition, and impurities in the helium coolant. • Evaluate grain boundary engineering as a method to mitigate stress-assisted grain boundary oxidation and creep crack growth of candidate alloys in impure helium. The maximum primary helium coolant temperature in the high-temperature reactor is expected to be 850-1,000°C.Corrosion may involve oxidation, carburization, or decarburization mechanisms depending on the temperature, oxygen partial pressure, carbon activity, and alloy composition. These corrosion reactions can substantially affect long-term mechanical properties such as crack- growth rate and fracture

Flash chemistry: flow chemistry that cannot be done in batch.

Science.gov (United States)

Yoshida, Jun-ichi; Takahashi, Yusuke; Nagaki, Aiichiro

2013-11-04

Flash chemistry based on high-resolution reaction time control using flow microreactors enables chemical reactions that cannot be done in batch and serves as a powerful tool for laboratory synthesis of organic compounds and for production in chemical and pharmaceutical industries.

Molecular dynamics and density functional simulations of tungsten nanostructure formation by helium plasma irradiation

International Nuclear Information System (INIS)

Ito, A.M.; Takayama, A.; Oda, Y.

2014-10-01

For the purposes of long-term use of tungsten diverter walls, it is necessary to suppress the surface deterioration due to the helium ash which induces the formations of helium bubbles and tungsten fuzzy nanostructures. In the present paper, the formation mechanisms of helium bubbles and tungsten fuzzy nanostructures were explained by the four-step process which is composed of the penetration process, the diffusion and agglomeration process, the helium bubble growth process and the tungsten fuzzy nanostructure formation process. The first to third step processes of the four-step process were investigated by using binary collision approximation, density functional theory and molecular dynamics, respectively. Furthermore, newly developed molecular dynamics and Monte-Carlo hybrid simulation has successfully reproduced the early formation process of tungsten fuzzy nanostructure. From these simulations, we here suggest the following key mechanisms of the formations of helium bubbles and tungsten fuzzy nanostructures: (1) By comparison between helium, neon, argon and hydrogen, the noble gas atoms can agglomerate limitlessly not only at a vacancy but also at an interstitial site. In particular, at the low incident energy, only helium atoms bring about the nucleation for helium bubble. (2) In the helium bubble growth process, the strain of the tungsten material around a helium atom is released as a dislocation loop, which is regarded as the loop punching phenomenon. (3) In the tungsten nanostructure formation process, the bursting of a helium bubble forms cavity and convexity in the surface. The helium bubbles tend to be grown and to burst at the cavity region, and then the difference of height between the cavity and convexity on the surface are enhanced. Consequently, the tungsten fuzzy nanostructure is formed. (author)

Operating Manual of Helium Refrigerator (Rev. 2)

Energy Technology Data Exchange (ETDEWEB)

Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

2002-07-01

A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

Modelling and mitigation of Flash Crashes

OpenAIRE

Fry, John; Serbera, Jean-Philippe

2017-01-01

The algorithmic trading revolution has had a dramatic effect upon markets. Trading has become faster, and in some ways more efficient, though potentially at the cost higher volatility and increased uncertainty. Stories of predatory trading and flash crashes constitute a new financial reality. Worryingly, highly capitalised stocks may be particularly vulnerable to flash crashes. Amid fears of high-risk technology failures in the global financial system we develop a model for flash crashes....

Electro-optical muzzle flash detection

Science.gov (United States)

Krieg, Jürgen; Eisele, Christian; Seiffer, Dirk

2016-10-01

Localizing a shooter in a complex scenario is a difficult task. Acoustic sensors can be used to detect blast waves. Radar technology permits detection of the projectile. A third method is to detect the muzzle flash using electro-optical devices. Detection of muzzle flash events is possible with focal plane arrays, line and single element detectors. In this paper, we will show that the detection of a muzzle flash works well in the shortwave infrared spectral range. Important for the acceptance of an operational warning system in daily use is a very low false alarm rate. Using data from a detector with a high sampling rate the temporal signature of a potential muzzle flash event can be analyzed and the false alarm rate can be reduced. Another important issue is the realization of an omnidirectional view required on an operational level. It will be shown that a combination of single element detectors and simple optics in an appropriate configuration is a capable solution.

The relativistic feedback discharge model of terrestrial gamma ray flashes

Science.gov (United States)

Dwyer, Joseph R.

2012-02-01

As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two- and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.

Henry's law and accumulation of weak source for crust-derived helium: A case study of Weihe Basin, China

Directory of Open Access Journals (Sweden)

Yuhong Li

2017-12-01

Full Text Available Crust-derived helium is generated from the radioactive decay of uranium, thorium and other radioactive elements in geological bodies. Compared with conventional natural gas, helium is a typical weak source gas as a result of extremely slow generation rate and absence of helium-generating peak. It is associated with methane or carbon dioxide reservoirs frequently and related to groundwater closely. Helium can meet the industry standard with 0.1% in volume fraction. In order to study the accumulation mechanism of helium, the previous research on Henry's coefficient and solubility of helium, nitrogen and methane are summarized and the key roles of Henry's Law in the helium migration, accumulation and preservation are discussed by simulating calculation taking Weihe Basin as an example. According to the Law, the gas solubility in dilute solution is controlled by the gas partial pressure and the Henry's coefficient. Compared with the carrier gases, the Henry's constant of helium is high, with striking difference at low and high temperature. In addition, the helium partial pressure is greatly different in helium source rocks and gas reservoirs, resulting in the great differences of helium solubility in the two places. The accumulation progresses are as follows. Firstly, helium can dissolve into water and migrate out of helium source rocks due to the high helium solubility, which is caused by high helium partial pressure and high temperature in source rock. Secondly, when dissolved helium is transported to the shallow gas reservoir, it is prone to be out of solution and into reservoir due to the extremely low partial pressure and low temperature. Meanwhile part of carrier gases dissolves into water, as if helium is “replaced” out. Furthermore, the low concentration funnel of dissolved helium is formed near the gas reservoir, then other dissolved helium continues to migrate towards the gas reservoir, which greatly improves the helium accumulation

RELATIONSHIP BETWEEN FLASH POINTS OF SOME BINARY ...

African Journals Online (AJOL)

B. S. Chandravanshi

Miscellaneous binary blends containing solvent neutral-150 (SN-150), ... viscosity, the flash point test has always been a standard part of a lubricant's specification. ... between structure and flash points of organic compounds [5-12] and fuels [13, 14]. ... in binary mixtures, the gaps between flash points would be high enough.

NO signatures from lightning flashes

Science.gov (United States)

Stith, J.; Dye, J.; Ridley, B.; Laroche, P.; Defer, E.; Baumann, K.; Hübler, G.; Zerr, R.; Venticinque, M.

1999-07-01

In situ measurements of cloud properties, NO, and other trace gases were made in active thunderstorms by two research aircraft. Concurrent measurements from a three-dimensional (3-D) VHF interferometer and the 2-D National Lightning Detection Network were used to determine lightning frequency and location. The CHILL Doppler radar and the NOAA-WP-3D Orion X band Doppler radar were also used to measure storm characteristics. Two case studies from the (STERAO) Stratosphere-Troposphere Experiments: Radiation, Aerosols, and Ozone project in northeastern Colorado during the summer of 1996 are presented. Narrow spikes (0.11-0.96 km across), containing up to 19 ppbv of NO, were observed in the storms. Most were located in or downwind of electrically active regions where the NO produced by lightning would be expected. However, it was difficult to correlate individual flashes with NO spikes. A simple model of the plume of NO from lightning is used to estimate NO production from the mean mixing ratio measured in these spikes. The estimates range from 2.0×1020 to 1.0×1022 molecules of NO per meter of flash length.

PG-100 helium loop in the MR reactor

International Nuclear Information System (INIS)

Ponomarev-Stepnoj, N.N.; Yakovlev, V.V.; Tikhonov, N.I.

1983-01-01

Main systems and production equipment units of PG-100 helium loop in the MR reactor are described. Possible long-term synchronizing operation of loop and reactor as well as possibility of carrying out life-time tests of spherical fuel elements and materials are shown. Serviceability of spherical fuel elements under conditions similar to the ones of HTGR-50 operation as well as high serviceability of cleanup system accepted for HTGR are verified. Due to low radiation dose the loop is operated without limits, helium losses in the loop don't exceed 0.5%/24 h, taking account of experimental gas sampling

Imprints from the solar cycle on the helium atom and helium pickup ion distributions

Directory of Open Access Journals (Sweden)

D. Rucinski