Extended Self Similarity

The solar wind is a highly turbulent and intermittent medium at frequencies between 10 -4 and 10 -1 Hz. Power spectra are used to look at fluctuations in the components of the magnetic field at high frequencies over a wide range of latitudes. Results show steady turbulence in the polar regions of the Sun and a more varied environment in the equatorial region. The magnetic field fluctuations exhibit anomalous scaling at high frequencies. Various models have been proposed in an attempt to better understand the scaling nature of such fluctuations in neutral fluid turbulence. We have used the Ulysses fast latitude scan data to perform a wide ranging comparison of three such models on the solar wind magnetic field data: the well-known P model, in both its Kolmogorov and Kraichnan forms, the lognormal cascade model and a model adapted from atmospheric physics, the G infinity model. They were tested by using fits to graphs of the structure function exponents g(q), by making a comparison with a non-linear measure of the deviation of g(q) from the non-intermittent straight line, and by using extended self similarity technique, over a large range of heliolatitudes. Tests of all three models indicated a high level of intermittency in the fast solar wind, and showed a varied structure in the slow wind, with regions of apparently little intermittency next to regions of high intermittency, implying that the slow wind has no uniform origin. All but one of the models performed well, with the lognormal and Kolmogorov P model performing the best over all the tests, indicating that inhomogeneous energy transfer in the cascade is a good description. The Kraichnan model performed relatively poorly, and the overall results show that the Kraichnan model of turbulence is not well supported over the frequency and distance ranges of our data set. The G infinity model fitted the results surprisingly well and showed that there may very well be important universal geometrical aspects of intermittency over many physical systems.

We propose a novel method for analysing back-ground seismic noise data before an earthquake by using Markov Time Scale algorithm to predict large earthquakes.Alert time obtained based on the data from broad-band stations by analyzing 200 earthquakes with magnitude grater than 4.5, that occurred in Iran , between January 1 and December 30, 2009. The numerical coefficients for each area will be estimated from the data collected for the area. The Markov Time Scale algorithm analysis can be extended to all the stations around the world.

We propose a novel method for analysing back-ground seismic noise data before an earthquake by using Markov Time Scale algorithm to predict large earthquakes.Alert time obtained based on the data from broad-band stations by analyzing 200 earthquakes with magnitude grater than 4.5, that occurred in Iran , between January 1 and December 30, 2009. The numerical coefficients for each area will be estimated from the data collected for the area. The Markov Time Scale algorithm analysis can be extended to all the stations around the world.

The high-order statistics of fluctuations in velocity gradients in the crossover range from the inertial to the Kolmogorov and sub-Kolmogorov scales are studied by direct numerical simulations (DNS) of homogeneous isotropic turbulence with vastly improved resolution. The derivative moments for orders 0 n 8 are represented well as powers of the Reynolds number, Re, in the range 380 Re 5275, where Re is based on the periodic box length L x . These low-Reynolds-number flows give no hint of scaling in the inertial range even when extended self-similarity is applied. Yet, the DNS scaling exponents of velocity gradients agree well with those deduced, using a recent theory of anomalous scaling, from the scaling exponents of the longitudinal structure functions at infinitely high Reynolds numbers. This suggests that the asymptotic state of turbulence is attained for the velocity gradients at far lower Reynolds numbers than those required for the inertial range to appear. We discuss these findings in the light of multifractal formalism. Our numerical studies also resolve the crossover of the velocity gradient statistics from Gaussian to non-Gaussian behaviour that occurs as the Reynolds number is increased.

Using data of a direct numerical simulation (DNS) of 3D turbulence it is shown that the moments of order between 1 and 6 of both longitudinal and transverse components of velocity increment for forced as well as decay turbulence can be described by stretched lognormal distribution for all scales from the dissipation to the inertial ranges and for all values of Reynolds number investigated in this DNS (50 < R < 459). A new (local) version of extended self-similarity has been used for this purpose. Effects of vortex structure on increment of velocity field in forced and in decay turbulence are briefly discussed.

In this paper we report numerical and experimental results on the scaling properties of the velocity turbulent fields in several flows. The limits of a new form of scaling, named Extended Self Similarity(ESS), are discussed. We show that, when a mean shear is absent, the self scaling exponents are universal and they do not depend on the specific flow (3D homogeneous turbulence, thermal convection , MHD). In contrast, ESS is not observed when a strong shear is present. We propose a generalized version of self scaling which extends down to the smallest resolvable scales even in cases where ESS is not present. This new scaling is checked in several laboratory and numerical experiment. A possible theoretical interpretation is also proposed. A synthetic turbulent signal having most of the properties of a real one has been generated.

Measurements have been made using Laser Doppler Anemometry (LDA) in a fully developed turbulent channel flow with the aim of determining second-order and third-order temporal and spatial structure functions of the longitudinal velocity fluctuation. A reliable determination of these moments requires the data to be corrected for the effect of noise. Correction procedures are outlined, based on the behaviour of temporal or spatial correlation functions in the limit of small time intervals or small separations. No a priori assumptions about the nature of the noise are made so that the procedure should be quite general. The corrected LDA data indicate that, especially for spatial separations, the effect of noise can be felt even within the inertial range. The corrected structure functions should allow an unambiguous assessment to be made of Taylor's hypothesis and of the extended self-similarity (ESS) method; examples are given in each case. Temporal structure functions obtained by hot wire anemometry (HWA) are much less affected by noise than the LDA data.

Using a generalization of extended self-similarity we have studied local scaling properties of incompressible homogeneous isotropic 3D turbulence in a direct numerical simulation. We have found that these properties are consistent with lognormal-like behavior of the velocity increments with moderate amplitudes for space scales r beginning from Kolmogorov length η up to the largest scales, and in the whole range of the Reynolds numbers: 50 ≤ R λ ≤ 459. The locally determined intermittency exponent µ(r) varies with r; it has a maximum at scale r = 14η, independent of R λ .

The scaling properties of the temperature structure functions are experimentally investigated in turbulent Rayleigh-BBnard convection at low Prandtl number. It is found that the temperature has the same scaling exponents of a passive scalar in 3D homogeneous isotropic turbulence. These exponents are obtained from the property of extended self-similarity, extending the scaling laws to the case of moderate Reynolds numbers.

The scaling properties of the temperature structure functions are experimentally investigated in turbulent Rayleigh-BBnard convection at low Prandtl number. It is found that the temperature has the same scaling exponents of a passive scalar in 3D homogeneous isotropic turbulence. These exponents are obtained from the property of extended self-similarity, extending the scaling laws to the case of moderate Reynolds numbers.

We measure temperature fluctuations in the Rayleigh-Bénard apparatus, which is a closed cylindrical container with the bottom wall heated and the top wall cooled. The aspect ratio, which is the diameter-to-height ratio of the apparatus, is unity. The Rayleigh number is 1.5ϫ10 11. The working fluid is cryogenic helium gas. We compute temperature structure functions up to order 16, and use extended self-similarity to obtain scaling exponents in the Bolgiano regime. In contrast to passive scalars, the scaling exponents tend not to saturate with the order of the structure function, suggesting the absence of ramplike structures in temperature traces of convective motion.

In this work we studied the effect of grain size on retention and transport of deuterium in tungsten. Tungsten consists of grains with distinct crystal structure that are separated by grain boundaries. These grain boundaries can act as weak trapping sites for hydrogen isotopes and also act as a faster way for deuterium diffusion into the bulk of the material [1]. From the results of this study we can extrapolate the influence of grain size on tritium retention and transport in the walls of future fusion reactors made of tungsten. We carried out the experiment on three polycrystalline samples of tungsten that have different average grain sizes and a monocrystalline sample with surface orientation (100). In tungsten, native defects in the crystal mesh are present which act as strong trapping sites for hydrogen isotopes. Additional defects are created when the material is bombarded by particles from the hydrogen plasma and by neutron bombardment. In experiments samples were bombarded b...

The ceramic material Li 2 ZrO 3 has superior thermo-physical and thermo-chemical properties and is highly compatible with other blanket materials used in nuclear reactors. Like LiAlO 2 , it could be used in the form of an annular pellet in tritium-producing burnable absorber rods (TPBARs) to produce tritium( 3 H) upon thermal neutron irradiation of lithium isotope ( 6 Li). The radiation damaged pellet crystal contains vacancies, defects of its constituent elements, and several other trapping sites which hinder the 3 H diffusion process and releasing behavior. In this study, we investigate the diffusion mechanisms of 3 H and O 3 H species in Li 2 ZrO 3 ceramic pellet in order to understand the effects on diffusion barriers and diffusion coefficients due to the presence of interstitial and substitutional Li defects, hydroxide (O-3 H) vacancy defect, and of the interactions of 3 H with O-vacancies in the radiation damaged Li 2 ZrO 3 crystal. We consider several possible diffusion pathways of interstitial and substitutional 3 H and its species in a defective supercell and calculate the activation energy barrier profiles. We find that the smallest activation energy barrier is 0.3 eV and corresponding diffusion coefficient at 600 K is 1.93x10 -9 m 2 /s for 3 H substitutional diffusion. The 3 H smallest interstitial diffusion barrier and diffusion coefficient are found to be 0.34 eV and m 2 /s. By examining several channels for diffusion, 3.25 × 10 -9 our results show the most likely diffusion mechanism of 3 H migration is occurring along the c-direction by exchange of 3 H within and between different Li sites. Our calculated results reveal that the smallest energy barrier for O 3 H diffusion is 0.75 eV which is when O 3 H is diffusing to the Li vacancy pair and O-Li vacancy pair and the corresponding diffusion coefficient is 6.31x10 -13 m 2 /s. In terms of 3 H diffusion, the obtained results indicate that the performance of Li 2 ZrO 3 could be better than γ-LiAlO 2 , a widely used ceramic material in TPBAR for producing 3 H.

In a solid tritium breeding blanket, Li 4 SiO 4 is in contact with reduced activation ferritic/martensitic (RAFM) steel at high temperatures for years and forms a corrosion layer. The effects of the corrosion layer on the hydrogen isotope permeability of a RAFM steel CLF-1 were thus investigated. X-ray diffraction, secondary ion mass spectroscopy and spherical aberration corrected transmission electron microscopy demonstrated the formation of a three-layered corrosion product, comprising a middle layer of LiFeO 2 and an inner layer of LiCrO 2. Li 4 SiO 4 powder with the (104) crystal plane orientation was adsorbed on the outermost surface of the CLF-1, forming a nanoscale layer with a thickness of ∼150 nm. Deuterium permeation tests show that the deuterium permeability of the corroded samples was two orders of magnitude higher than that of the blank substrate that was pre-heated for 30 days, but one order of magnitude lower than that of the blank substrate that was not preheated. The CLF-1 corroded for 10 days exhibited the highest deuterium permeation flux. There was a decrease in the deuterium permeability of the steel that corroded for 15 and 30 days; thus, there was a decrease in the permeability with an increase in the corrosion period. By the weighting method and TEM analysis, a cracking and reoxidation process was proposed to explain the decreasing deuterium permeability of CLF-1 during corrosion by Li 4 SiO 4. Our study provides a promising approach for preventing tritium permeation.

We present a pseudospectral study of the randomly forced Navier-Stokes equation (RFNSE) stirred by a stochastic force with zero mean and a variance ϳk 42d2y , with k the wave vector and the dimension d 3. We provide the first evidence for multiscaling of velocity structure functions for y $ 4. We extract the multiscaling exponent ratios z p ͞z 2 by using extended self-similarity, examine their dependence on y, and show that, if y 4, they are in agreement with those obtained for the Navier-Stokes equation forced at large spatial scales (3DNSE). Also well-defined vortex filaments, which appear clearly in studies of the 3DNSE, are absent in the RFNSE.

We present a study of the multiscaling of time-dependent velocity and magnetic-field structure functions in homogeneous, isotropic magnetohydrodynamic (MHD) turbulence in three dimensions. We generalize the formalism that has been developed for analogous studies of time-dependent structure functions in fluid turbulence to MHD. By carrying out detailed numerical studies of such time-dependent structure functions in a shell model for three-dimensional MHD turbulence, we obtain both equal-time and dynamic scaling exponents.

Recently, Tritium Plasma Experiment (TPE), a unique high-flux linear plasma device that can handle beryllium, tritium and neutron-irradiated plasma facing materials, has undergone major upgrades in its electrical and control systems. The upgrade has improved worker occupational safety, and enhanced TPE plasma performance to better simulate extreme plasma-material-interaction (PMI) conditions expected in ITER, Fusion Nuclear Science Facility (FNSF) and demonstration fusion power plant (DEMO). The PMI determines a boundary condition for diffusing tritium into bulk plasma-facing components (PFCs) and plays critical role in in-vessel and ex-vessel safety assessments. Enhancing surface capabilities for tritiumcontaminated and radioactive samples is crucial for the PMI sciences in burning plasma long pulse operation. The TPE Upgrade and improvement of surface diagnostic capabilities for tritium-contaminated and radioactive samples at STAR facility help enhance tritium and nuclear PMI sciences for the development of reliable PFCs and tritium fuel cycle in ITER, FNSF and DEMO.

The SORGENTINA-RF project aims to develop a 14 MeV fusion neutron source to produce medical radioisotopes with special focus on $$^{99}$$ 99 Mo. The facility is based on a positive ion source with an acceleration stage to produce a deuterium (D$$^{+})$$ + ) and tritium (T$$^{+})$$ + ) ion beam that, impacting on a titanium-coated rotating target, allows fusion reactions to take place. Maximizing the neutron production rate is one of the main issues to be addressed in the project and the optimization of some key parameters of the ion beam is of paramount importance in this regard. In this study, a methodology is discussed to reach a definition of the beam characteristics for an effective and sustainable operation of the plant. The most convenient layout that has been found out is based on a single ion source fed by a deuterium and tritium gas mixture. Eventually, a series of considerations about the operation of the ion source and fuel cycle have been drawn.

In this work the relation between integral scale and fractal dimension and the type of stratification in fully developed turbulence is analyzed. The integral scale corresponds to that in which energy from larger scales is incoming into a turbulent regime. One of the aims of this study is the understanding of the relation between the integral scale and the bulk Richardson number, which is one of the most widely used indicators of stability close to the ground in atmospheric studies. This parameter will allow us to verify the influence of the degree of stratification over the integral scale of the turbulent flows in the atmospheric boundary layer (ABL). The influence of the diurnal and night cycles on the relationship between the fractal dimension and integral scale is also analyzed. The fractal dimension of wind components is a turbulent flow characteristic, as has been shown in previous works, where its relation to stability was highlighted. Fractal dimension and integral scale of the horizontal (u) and vertical (w) velocity fluctuations have been calculated using the mean wind direction as a framework. The scales are obtained using sonic anemometer data from three elevations 5.8, 13 and 32 m above the ground measured during the SABLES 98 field campaign (Cuxart et al., 2000). In order to estimate the integral scales, a method that combines the normalized autocorrelation function and the best Gaussian fit (R 2 ≥ 0.70) has been developed. Finally, by comparing, at the same height, the scales of u and w velocity components, it is found that the turbulent flows are almost always anisotropic.

We present an introductory overview of several challenging problems in the statistical characterisation of turbulence. We provide examples from fluid turbulence in three and two dimensions, from the turbulent advection of passive scalars, turbulence in the one-dimensional Burgers equation, and fluid turbulence in the presence of polymer additives.

The Kolmogorov relation for the third order structure function is used to derive the energy spectrum in the far dissipation range (k~oo). With no unspecified constants and methods from matched asymptotic expansions, a uniformly valid form for the inertial through the dissipative ranges is obtained. An analogous energy spectrum is presented. This is compared with the results of physical and numerical experiments on the energy spectra E(k) The. theoretical predictions are found to deviate by not more than a few percent from data in the entire range of wave numbers where the energy spectrum E(k) varies by more than 30 orders of magnitude.

The existence of the "21" spectral law in wall turbulence is explained by the effect of superposition of Kolmogorov's eddy cascades generated at all possible distances from the wall, within an equilibrium layer. This concept is justified using only the well-known properties of wall-bounded flows. The presence of coherent structures appears to be not essential for the inverse-power law. The model predicts the 21 scaling for the range ͑1͞H͒ # k # ͑1͞z͒, which agrees very well with the measurements (k is the wave number, H is the external scale of the flow, and z is the distance from the wall).

The SORGENTINA-RF project aims to develop a 14 MeV fusion neutron source to produce medical radioisotopes with special focus on $$^{99}$$ 99 Mo. The facility is based on a positive ion source with an acceleration stage to produce a deuterium (D$$^{+})$$ + ) and tritium (T$$^{+})$$ + ) ion beam that, impacting on a titanium-coated rotating target, allows fusion reactions to take place. Maximizing the neutron production rate is one of the main issues to be addressed in the project and the optimization of some key parameters of the ion beam is of paramount importance in this regard. In this study, a methodology is discussed to reach a definition of the beam characteristics for an effective and sustainable operation of the plant. The most convenient layout that has been found out is based on a single ion source fed by a deuterium and tritium gas mixture. Eventually, a series of considerations about the operation of the ion source and fuel cycle have been drawn.

A description of the work performed to set up an apparatus to measure permeation rates of hydrogen and tritium in 304L stainless steel is presented. This is in preparation for future work to find and qualify candidate materials resistant to tritium permeation in various advanced nuclear systems.

The Laser Inertial Fusion Energy (LIFE) power plant is being designed to deliver a transformative source of safe, secure, sustainable electricity, in a time scale that is consistent with the global energy market needs. The LIFE market entry plant will demonstrate the feasibility of a closed fusion fuel cycle, including tritium breeding, extraction, processing, refueling , accountability and safety, in a steady-state power-producing device. While many fusion plant designs require large quantities of tritium for startup and operations, a range of design choices made for the LIFE fuel cycle act to reduce the inprocess tritium inventory. The high fractional burn-up (~30%) in an Inertial Fusion Energy (IFE) capsule relaxes the tritium breeding requirements, while the use of only milligram quantities of fuel per shot and choice of a pure lithium heat transfer fluid substantially reduce the amount of material entrained in the facility. Additionally, the high solubility of tritium in the lithium breeder is expected to mitigate the need for development of permeation barriers in the engine systems, normally required to control routine releases within the allowable regulatory limits. The present paper offers an overview of the design of the LIFE fuel cycle, including a summary of the technology development plan consistent with the delivery schedule of the LIFE market entry plant.

Unique design of the cryogenic target with a gold conical guide and a fuel feeding capillary has been developed for the Fast Ignition Realization Experiment (FIREX) project at the Institute of Laser Engineering (ILE), Osaka University. In the scheme, the deuterium gas is to be fed in a foam layer of the shell and solidified. In the case of a foam shell filled with solid fuel, it is worried that bubble-like void may remain in the cell after the liquid-solid transition. Filling fraction of solid fuel in the Resolcinol-Formalehyde foam of a surrogate target was investigated by using an interference imaging technique. It was shown that the optimization of cooling speed and temperature gradient was quite promising to make a uniform solid layer with a low void fraction.

An assumption common to many approaches to understanding and modeling turbulent mixing is that the statistics of a passive scalar at small length scales will approach the analogous statistics of the velocity field as the scale separation increases between the flow-specific outer scales and the small scales of interest. This assumption follows from the hypotheses of Kolmogorov, Oboukhov, Corrsin, and Batchelor, although it is well recognized that differences in the scalar and velocity dynamics prevent the overall statistics of the two being the same. Considerable research on the effect of Reynolds number and Schmidt number on the scalar statistics has shown that the assumption is not very good at either high Reynolds number or high Schmidt number individually. Because of limitations in laboratory measurements, direct numerical simulations (DNSs), and in situ measurements of the ocean and atmosphere, it is difficult to obtain data in which the Reynolds number is high enough for an unequivocal inertial-convective subrange, and the Schmidt number is simultaneously high enough for a clear viscous-convective subrange. Our hypothesis is that, when both subranges exist, then there is sufficient scale separation in the velocity field for its statistics to be approximately universal, and also sufficient additional scale separation for the scalar to relax so that its small-scale statistics approach those of the velocity. We explore this hypothesis with DNS resolved on up to 14 256 × 14 256 × 14 256 grid points, Taylor Reynolds number Re λ = 633, and Schmidt number Sc = [0.1, 0.7, 1.0, 7.0], with the aim of studying the validity of this hypothesis for mixing in air and water. When the Schmidt number is not greater than unity at high Reynolds number, a viscous-convective subrange does not exist and we find that small-scale isotropy, the intermittency exponent, and the probability density function of the scalar dissipation rate are all much different from the analogous velocity statistics, as reported widely in literature. However, when the Schmidt number is greater than unity at high Reynolds number, inertial-convective and viscous-convective subranges both exist, and the velocity and scalar statistics are similar. Since this similarity is a consequence of the presence of both inertial convective and viscous convective subranges, it is achieved only at both high Reynolds and Schmidt numbers, and the statistics show a sharp change when the Schmidt number is changed from from 1 to 7. This suggests that at high Reynolds numbers, the modeling assumption of similarity between velocity and scalar statistics is valid for mixing in water, but not in air.

wake behind a sphere, rotating about an axis aligned with the streamwise direction, has been experimentally investigated in a water tunnel using LIF visualizations and PIV measurements. The measurements focused on the evolution of the flow regimes that appears depending of two control parameters, namely the Reynolds number Re and the dimensionless rotation or swirl rate Ω which is the ratio of the maximum azimuthal velocity of the body to the free stream velocity. In the present investigation, we covers the range of Re smaller than 400 and Ω from 0 and 1.5. Different wakes regimes such as an axisymmetric base flow, a low frequency frozen state, and an single and double helicoidal mode are represented in the (Re, Ω) parameter plane.

Data from SABLES98 experimental campaign have been used in order to study the influence of stability (from weak to strong stratification) on the flux-profile relationships for momentum and heat: φ m and φ h. Standard instrumentatio n, 14 thermocouples and 3 sonic anemometers at three levels (5.8, 13.5 and 32 m) were available from 10 to 28 September 1998 and calculations are done in order to extract structure functions and intermittency. The results show increasing values of φ m and φ h with increasing stability parameter and then values remain constant. As a consequence of these constant, but different values of φ m and φ h for strong stability, when linear similarity functions (Businger et al., 1971) are used to calculate surface fluxes of momentum and heat an important underestimation of the turbulent mixing is produced. The differences in structure and higher order moments between stable and neutral turbulence is studied in terms of turbulent intermittent mixing and velocity PDF's.

The High Temperature Isotopic Exchange (HITEX) process has been proposed as a simple and reliable option for detritiating impurities in the ITER plasma exhaust. 1 The process relies on the well known principle of catalytic equilibration, does not involve complicated decomposition reactions, and avoids the formation of tritiated water. The original HITEX process was conceived as a simple batch system which could yield extremely high detritiation factors (~ 10 9). However, batch operation (for an ITER scale/impurity feed compositions) necessitates the holdup of tritium inventory (101 gT) equivalent to one batch in the HITEX feed tank. This paper compares batch and once-through HITEX options in light of calculated and experimental results. Tritium inventories, hydrogen swamping rates and Decontamination Factors (DF's) are compared with the objective of optimizing the process configuration for ITER.

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • An inertial electrostatic confinement fusion (IECF) device is simulated. • In the IECF device, the neutron production rate (NPR) is increased with the broadening of the distribution function of ions. • The IECF device is used with D-D and D-T fuel to generate neutron and proton beams. • To increase the NPR, instead of the net D-D fuel, it is highly beneficial to use a D-T fuel mixture. • The NPR of the D-T fuel mixture with a 50%-50% ratio is approximately 250 times that of pure fuel.

Alumina coating, with a thickness of 1 m, has been manufactured by Pulsed Laser Deposition on EURO-FER. A whole characterization of the interface, bare and coated, with stagnant Pb-17Li eutectic for 1000 h at 550 • C was performed using scanning electron microscopy, energy dispersive x-ray spectroscopy and secondary ion mass spectrometry. The results show that uncoated samples are damaged and suffer loss of material due to a solution process of the steel into the liquid metal, while corrosion process is insignificant for coated samples. Therefore, these results suggest a good performance of the alumina coatings under the test conditions.

Tritium management is one of the main challenges that future nuclear fusion energy has to achieve. Accurate tritium monitoring is a basic task in order to have relying fusion reactors. High temperature sensors have to be developed to make this monitoring a reality. Hydrogen sensors based on solid-state electrolytes can be a reliable option to perform this monitoring. These types of sensors offer resistance to harsh chemical environments, temperature depending conductivity and quick and easy to measure signals. Potentiometric and amperometric hydrogen sensors based on solid-state electrolytes were previously studied in our research group. These previous sensors contained a pellet-shaped solid-state electrolyte. Using a one-end closed tube geometry the active area of the sensor increases. This new shape was obtained by a slip casting process. The satisfactory results obtained with both amperometric and potentiometric sensors present a promising path to the development of high temperature tritium sensors that could be used in the breeding blankets of the future nuclear fusion reactors. In the present work, amperometric sensors performance has been improved by increasing the electrolyte's active area. Enlarging the electrolyte's area gives the sensor more sensitivity and reduces its limit of detection and quantification. Analytical parameters of the sensor were compared to other electrochemical hydrogen sensors.

The rice grain detachment strength under a straight pull is much greater than the detachment strength due to a perpendicular pull1). The field loss during rice harvesting could be minimized by avoiding the impact on the rice grain, especially the impact in the perpendicular direction to the rice pedicel. Rice grain threshing, on the other hand,

The rice grain detachment strength under a straight pull is much greater than the detachment strength due to a perpendicular pull1). The field loss during rice harvesting could be minimized by avoiding the impact on the rice grain, especially the impact in the perpendicular direction to the rice pedicel. Rice grain threshing, on the other hand,

Submitted for the DFD16 Meeting of The American Physical Society A Numerical Simulation of the Density Oscilator 1 SERGIO HER-NANDEZ ZAPATA, ERICK JAVIER LOPEZ SANCHEZ, GERARDO RUIZ CHAVARRIA, Facultad de Ciencias, UNAM-In this work we carry out a numerical simulation for the dynamics that originates when a fluid (salty water) is located on top of another less dense fluid (pure water) in the presence of gravity. This is an unstable situation that leads to the development of intercalating lines of descending salty water and ascending pure water. Another situation is studied where the fluids are in two containers joined by a small hole. In this case a time pattern of alternating flows develops leading to an oscillator. The study of the velocity field around the hole shows than in a certain interval of time it develops intercalating lines like in the former situation. An interesting result is the fact that when a given fluid is flowing in one direction a vorticity pattern develops in the other fluid. The Navier-Stokes, continuity and salt diffusion equations, are solved numerically in cylindrical coordinates, using a finite difference scheme in the axial and radial directions and a Fourier spectral method for the angular coordinate. On the other hand, the second order Adams-Bashfort method is used for the time evolution. The results are compared to a numerical simulation of a pedestrian oscillator we developed based on the Hebling and Molnar social force model.

h i g h l i g h t s • Radiation enhanced deuterium absorption occurs for RB-SiC. • This type of radiation enhanced absorption is related to Si rather than to C. • Most of the radiation induced absorbed deuterium is released at about the foreseen blanket operation temperature.

Conditioning of plasma facing components (PFCs) using lithium (Li) evaporation has shown to improve plasma performance in fusion devices by imposing low recycling boundary conditions. It is important to understand the retention and sputtering dynamics of deuterium (D) in Li and Li compound (LieO and LieCeO) films to most efficiently make predictions on plasma performance. Energetic D 2 + incident on thin Li films is shown to readily form LiD leading to a lower Li sputtering yield than the sputtering yield of pure Li. Measured sputtering yields for thin LiD films agree with previous simulations and bulk erosion measurements. The He + sputtering yield of pure Li was 2-3 times higher than the sputtering yield of D 2 + on LiD. Incident 1000-1200 eV/D 2 + sputtered LieO films at a slower rate than D 2 + on LiD and LieCeO films.

Over the last 7-8 years, two quantitative analyzing methods-accelerator mass spectrometry (AMS) and full combustion (FC) followed by scintillation detection have been applied for determining the tritium activity concentrations in JET divertor tiles. These methods have two main differences-the range of detection and the spatial resolution-and are thus complementary. However, these differences can also complicate the comparison of the two techniques for typical JET divertor samples. Therefore a cross comparison exercise for tritium measurements was performed between the two methods using specially produced identical standard samples. The cross comparison measurements were performed firstly on the identical standard samples and were extended then to selected samples from the JET divertor tile (laser treated and non-treated samples from tile 14ING3B exposed in 2001-2004). The results obtained by AMS and FC agreed within an error limit of 10% for the standard samples and of 18% for the JET divertor samples. The results of this comparison study provided also useful information concerning the efficiency of tritium removal from the plasma facing surface of the divertor tiles by means of laser ablation.

The Fusion reactors will use deuterium and tritium as fuel since this reaction takes place at relative ly low temperature. Tritium is not available in nature, it must be produced in the fusion reactor blanket whi ch surrounds the plasma zone. The lithium bearing compound is av ailable in plenty in earth’s crust and by absorbing eutron, lithium produces tritium two reactions. So by desig nin the lithium blanket, more than one tritium ato m per fusion reaction can be produced. In the absence of thermon uclear reactions, the (D,T) neutrons which are ener getic 14MeV neutrons, are produced in the accelerator based n utron generators. In order to ensure that suffic ient amount of tritium would be produced in the future fusion r eactor blankets, experiments are carried out to irr adiate the lithium assembly using the available neutron source and measurements are done to estimate the tritium breeding. Also, it is required to extract the tritium produce d in the lithium blanket. This work c...

A self-developing gas chromatography (SDGC) process using a column packed with Pd-4 at.% Pt alloy powder was studied for hydrogen isotope separation at room temperature. Separation experiments of a deuterium-tritium (50% D 2-50% T 2) mixture were carried out using the same SDGC column. The concentrations of tritium in the recovered hydrogen isotope gas were 80 and 75% at 50 and 70% recovery of tritium, respectively. The result of the deuterium-tritium separation experiments suggested considerable potential for the applicability of the SDGC column to the D-T separation process at room temperature.

A b s t r a c t :The state of the Earth&#39;s fluid core is usually investigated on the basis of the observed features of geomagnetic variations at t he Earth&#39;s s urface. This task also involves difficulties associated with shorter time scale variations of internal origin which appear to b e undistinguishable from the external fields, at least

Data from SABLES98 experimental campaign have been used in order to study the influence of stability (from weak to strong stratification) on the flux-profile relationships for momentum and heat: φ m and φ h. Standard instrumentatio n, 14 thermocouples and 3 sonic anemometers at three levels (5.8, 13.5 and 32 m) were available from 10 to 28 September 1998 and calculations are done in order to extract structure functions and intermittency. The results show increasing values of φ m and φ h with increasing stability parameter and then values remain constant. As a consequence of these constant, but different values of φ m and φ h for strong stability, when linear similarity functions (Businger et al., 1971) are used to calculate surface fluxes of momentum and heat an important underestimation of the turbulent mixing is produced. The differences in structure and higher order moments between stable and neutral turbulence is studied in terms of turbulent intermittent mixing and velocity PDF's.

Controlled fusion based on the magnetic confinement of the plasma is one of the main aims of the Euro-fusion programme. In the fusion device, the hydrogen isotopes, in nuclear reactions, will produce helium nuclei. The products, as the ash, will be removed from the plasma in the region of the so-called divertor. Controlling the helium to hydrogen ratio in this ‘exhaust gas’ will provide information about the efficiency of the fusion process as well as of the efficiency of the helium removal system. One of the methods to perform this task is to study the properties of the discharge conducted in such exhaust gas. In this paper, the applicability of the dielectric barrier discharge (DBD) is studied. This preliminary experiment shows a great potential in applicability of this kind of discharge. The optical as well as pulse-height spectra were studied, both revealing very promising properties. In the optical spectrum, one can observe well separated hydrogen and helium spectral lines, wit...