Plug Region Research Articles

High-Performance Split-Gate Enhanced UMOSFET With p-Pillar Structure

In this paper, a split-gate resurf stepped oxide (RSO) vertical UMOSFET with p-pillar under the p+ plug region structure is proposed. The p-pillar could modulate the electric field of the drift region with the split-gate in 3-D and simultaneously brings electric field peaks at the sidewall junction between p-pillar and n-drift region. Thus the split-gate enhanced with p-pillar (SGEP) UMOS could increase the drift region doping concentration, reduce the on-state-specific resistance, and maintains the breakdown voltage as compared with the super junction and split-gate RSO UMOSs. Numerical simulation results show that the charge imbalance endurance of SGEP is also largely increased.

Electron Density and Fluctuation Measurements by Using a Frequency Multiplied Microwave Interferometer in the GAMMA 10 Anchor Cell

In GAMMA 10 two types of low frequency plasma fluctuations have been observed in the central cell by several diagnostics. One of which is the electron drift mode rotating azimuthally in the direction of electron diamagnetic drift rotation observed during ion cyclotron range of frequency heating (ICH). Recently a new interferometer has been installed in the mid-plane of the west anchor cell in order to investigate plasma density and density fluctuations in the anchor cell. By using the new interferometer, line-integrated density fluctuations are measured in the anchor cell and are compared to fluctuations in the central cell obtained by conventional interferometer systems. Density fluctuations around 10 kHz are observed in both cells during the ICH period and they are suppressed during the formation of axial confining potentials by electron cyclotron heating (ECH) in the plug regions.

Results of ECH Power Modulation Experimenting High and ELM-Like Heat Flux in GAMMA 10 Tandem Mirror

Electron cyclotron heating (ECH) power modulation experiments in the GAMMA 10 tandem mirror have been started in order to generate and control the high heat flux and to make the ELM (edge localized mode) like intermittent heat load pattern for divertor simulation studies. ECH for potential formation at the plug region (P-ECH) produces the electron flow with high energy along the magnetic filed line. The peak heat-flux of more than 10 MW/m2 was obtained during the ECH injection within the available power of ECH. It is found that arbitrary intermittent heat flux is possible by modulating the ECH power. 0.05 MJ/m2 heat pulse has been obtained with 380 kW 5ms ECH pulse, which indicates possibility of 0.5 MJ/m2 level with multi-MW ECH power.

Abstract 41: Integrin Outside-in Signaling Regulates Local Microenvironments Within Hemostatic Plugs

Prior studies have demonstrated that platelet activation within a hemostatic plug is heterogeneous. In particular, we recently determined that following vascular injury in vivo, a platelet mass is composed of distinct regions defined by the extent of platelet activation and other properties. At least two regions are apparent: a core of fully activated and degranulated platelets immediately adjacent to the site of injury, which is overlaid by a shell of less activated platelets that have not undergone a-granule secretion. Here, we tested the hypothesis that platelet accumulation and activation are regulated by the interaction of platelet signaling pathways with local microenvironments present within the different regions of a hemostatic plug using novel confocal intravital imaging approaches. We also hypothesized that integrin outside-in signaling plays a role in shaping the core region microenvironment. The results reveal that plasma volume (i.e. porosity) and solute transport velocity are significantly reduced in the interplatelet space of a hemostatic plug as compared to the bulk blood flow following laser-induced injury in mouse cremaster arterioles. Further, porosity and solute transport are significantly reduced in the core region of the hemostatic plug as a result of tight platelet packing, as compared to the outer shell region composed of loosely adherent platelets. To examine the impact of integrin outside-in signaling we utilized mice lacking beta 3 integrin cytoplasmic tail tyrosine phosphorylation (diYF). Prior studies have shown unstable platelet aggregation and defective fibrin clot retraction in diYF mice. We found diYF mice formed smaller hemostatic plugs following vascular injury in vivo. This decrease in total platelet accumulation was associated with reduced formation of the hemostatic plug core region and decreased fibrin generation, indicating decreased thrombin activity within the hemostatic plug. Taken together, these results support the hypothesis that tight platelet packing provides a protected microenvironment within a hemostatic plug in which bioactive molecules may accumulate to support platelet activation. They also identify a novel role for aIIbb3 outside-in signaling in hemostatic plug formation.

Na+ conductivity of the Na+-driven flagellar motor complex composed of unplugged wild-type or mutant PomB with PomA

PomA and PomB form the stator complex, which functions as a Na(+) channel, in the Na(+)-driven flagellar motor of Vibrio alginolyticus. The plug region of PomB is thought to regulate the Na(+) flow and to suppress massive ion influx through the stator channel. In this study, in order to measure the Na(+) conductivity of the unplugged stator, we over-produced a plug-deleted stator of the Na(+)-driven flagellar motor in Escherichia coli. The over-production of the plug-deleted stator in E. coli cells caused more severe growth inhibition than in Vibrio cells and that growth inhibition depended on the Na(+) concentration in the growth medium. Measurement of intracellular Na(+) concentration by flame photometry and fluorescent analysis with a Na(+) indicator, Sodium Green, revealed that over-production of the plug-deleted stator increased the Na(+) concentration in cell. Some mutations in the channel region of PomB or in the cytoplasmic region of PomA suppressed both the growth inhibition and the increase in intracellular Na(+) concentration. These results suggest that the level of growth inhibition correlates with the intracellular Na(+) concentration, probably due to the Na(+) conductivity through the stator due to the mutations.

Laser surface cleaning of carbonaceous deposits on diesel engine piston

Carbonaceous deposits of diesel engine piston are known to reduce engine durability and performance. Little research has been conducted on the deposits removal by laser technique. In this paper, the deposits on the surface of piston crown part before and after laser cleaning were examined by FTIR, XPS and SEM/EDX. The deposits were found to be distributed non-uniformly on the surface and they could be distinguished as a thicker layer of contaminants, located mainly in the plug region, while a thinner layer can be found in the remaining area. The main constituents of the deposits were analyzed as Fe3C, Fe3O4, possibly FeOOH, oxygenated hydrocarbons as well as carboxylates. Laser cleaning can remove Fe3C completely, and reduce the concentration of oxygenated hydrocarbons and carboxylates significantly. Fe2O3, instead of Fe3O4, was formed on the cleaned region.

Development of High Power ECH Systems for High and ELM-like Heat Flux in GAMMA 10 Tandem Mirror

Development of high power gyrotrons and electron cyclotron heating (ECH) systems for the power modulation experiments in GAMMA 10 have been started in order to generate and control the high heat flux and to make the ELM (edge localized mode) like intermittent heat load pattern for divertor simulation studies. ECH for potential formation at the plug region (P-ECH) produces the electron flow with high energy along the magnetic filed line. From the power scaling of confining potential and electron flux in GAMMA 10, the higher ECH power generates the higher confinement potential and the higher electron flux. The peak heat-flux of more than 10 MW/m 2 has been obtained during the ECH injection within the available power of ECH. This value almost corresponds to the steady-state heat load of the divertor plate of ITER. However, we need substantial upgrade of the heating power to approach the ITER level ELM energy density. For this purpose, MW power gyrotrons at 28 GHz have been started and the development is undergoing efficiently in the ECH system upgrade program with the collaboration of Japan Atomic Energy Agency (JAEA). c

A novel analytical method predicts plug boundaries of bingham plastic fluids for laminar flow through annulus

AbstractIn Bingham plastic fluids, a central pre‐yield or plug region exists in the middle of the concentric annular flow. In this region, the local shear stress is less than the dynamic yield stress, so the plug behaves like a rigid solid. This is the main feature that distinguishes the flow of a Bingham plastic fluid from that of a power law fluid. In this work, a simple‐to‐use correlation is developed to predict the boundaries of the plug of Bingham plastic fluids for laminar flow through annulus as a function of dimensionless yield stress and aspect ratio parameters for given values of the rheological constants, pressure gradient and the dimensions of the annulus. The results are found to be in excellent agreement with reported data in the literature with an average absolute deviation of less than 1.7%.The predictive tool is simple and straightforward and can be readily implemented in a standard spreadsheet program. The prime application of the method is as a quick‐and‐easy evaluation tool in engineering studies where plug boundaries of Bingham plastic fluids for laminar flow through annulus are being considered. The method may also serve as a benchmark in numerical and rigorous simulation studies.

Solidification dynamics in channeled viscoplastic lava flows

The influence of a viscoplastic lava rheology on the dynamics of channeled lava flows is analyzed using analogue experiments. The experiments used slurries of polyethylene glycol and kaolin, which flowed with a constant flux down an inclined channel under water. Three sets of complementary experiments are presented: isothermal, cooling, and solidifying flows which quantified the effects of the viscoplastic rheology on shear, internal convection and surface crust formation. The isothermal and cooling experiments showed the formation of unyielded central plug regions which were not broken up by the convective overturning. In the solidifying experiments flows fell into one of three regimes: a tube regime, in which crust covered the entire flow surface; a shear‐controlled regime, with a mobile raft of crust in the channel center and open shear zones near the walls; and a plug‐controlled regime where the width of the central crust was determined by the width of the central plug region. The crust coverage is parameterized in terms of two dimensionless parameters: the ratio wp of central plug region width to channel width and a parameter ϑ which characterizes the relative importance of the strain and solidification rates. Finally the dynamics of typical lava flows on Mt Etna and the 1984 Mauna Loa lava flow are examined. We show that our parameterization agrees with lava flow crust widths observed in the field and find that even small yield strengths have a major effect on crust coverage.

A study of mixture preparation and PM emissions using a direct injection engine fuelled with stoichiometric gasoline/ethanol blends

The effect of gasoline/ethanol blends in different blending proportions (E0, E10, E20, E50, E70, E85 as #% by volume) on the characteristics of size-resolved particulate number and mass concentrations was investigated in a single-cylinder optical access engine using a differential mobility spectrometer (DMS500) under cold and warm conditions (20°C, 80°C) at a stoichiometric condition (1500rpm, 0.5bar manifold absolute pressure). The effects on the fuel spray characteristics were also investigated by capturing the injection images and by post-processing to compare the temporal development of the spray with the different fuels. In-cylinder fFID (fast Flame Ionisation Detector) measurements were undertaken to assess the mixture in-homogeneity in the region of the spark plug. As the ethanol volumetric percentage increases, both the total Pn (Particulate number) and Pm (Particulate mass) increase by a maximum of 16 and 11 for cold conditions and 7 and 8 for warm conditions. This is in agreement with the natural flame chemiluminescence images which showed that fuels with high ethanol proportions generated more soot than fuels with small blending percentages of ethanol. Spray images and combustion analysis showed that ethanol addition results in protracted injection and combustion periods. The effect on spray characteristics is more profound under cold conditions than under warm conditions. The mixture in-homogeneity increases as the ethanol content increases for E50, E70, and E85 and this would explain the increased level of particulate emissions, although the trend is less clear for the lower ethanol content fuels.

FDTD Simulation Analysis for Improving Two-Dimensional Electron Density Distribution Measurement using Phase Imaging in GAMMA 10

A phase-imaging interferometer is used to measure the electron density distribution in the plug region in GAMMA 10. The electron density is derived by the Abel transform technique. We attempt to determine the plasma density distribution for an asymmetric Abel transform by using finite-difference time-domain simulations. Moreover, we try to construct the asymmetric Abel transform for an asymmetric plasma distribution.

GE2-2 Laser-Induced Fluorescence to Visualize Gas Mixture Formation in an Optically Accessible Hydrogen Engine(GE: Gas Engine,General Session Papers)

The established tracer laser-induced fluorescence (LIF) technique was newly adapted for the quantitative visualization of hydrogen inside an optically accessible hydrogen engine to investigate the processes of hydrogen-injection, mixture formation, ignition and combustion at motor-relevant operating points. Trimethylamine (TMA) has been seeded to the hydrogen and was thus used as a tracer for hydrogen when applying the LIF technique. End of injection (EOI) was varied at a constant speed of 2000 rpm and a load of 2 bar (IMEP) which represents typical part load condition. The results visualize the influence of EOI on the mixture formation, ignition and the beginning of combustion. The comparison of the visual results of four operating points shows how long it takes even in the case of hydrogen to get a homogeneous mixture at spark timing. Additionally, conventional engine data such as cylinder pressure, temperature, consumption, emissions etc. have been measured. Rough running engine due to uneven distribution in the region of the spark plug could be explained by single-shot images.

Isothermal dynamics of channeled viscoplastic lava flows and new methods for estimating lava rheology

This study analyses the influence of a viscoplastic lava rheology on the dynamics of lava flows. Using a multigrid‐based augmented Lagrangian scheme, we find a numerical solution for the flow of a Bingham fluid in a rectangular channel. The numerical results show that an internal viscoplastic rheology significantly modifies the velocity distribution within a lava flow through the development of plug regions whose size is determined by the magnitude of the yield strength. The flow rate, maximum surface velocity and central plug dimensions are determined as functions of the channel geometry and fluid rheology, and comparisons between these and several limiting analytical solutions confirm the accuracy of the numerical method used. The results are also compared to incorrect models which have been proposed previously in the literature. Several algorithms that extend the results to different sets of measured initial parameters are outlined; these calculate: (1) the flow depth when the fluid rheology (viscosity and yield strength) and downstream flow rate are given, (2) the flow depth when the fluid rheology and maximum downstream surface velocity are given, (3) the flow rate and fluid rheology when the flow depth, maximum surface velocity and surface plug width are given, and (4) the flow depth and rheology when the flow rate, maximum surface velocity and surface plug width are given. The use of these algorithms is demonstrated by considering the dynamics of a typical lava flow on Mount Etna, using measured rheological parameters and field observations.

ITER Equatorial Port plug engineering: Design and remote handling activities supported by Virtual Reality tools

In the context of ITER, CEA/IRFM has participated to the design and integration of several components in the Equatorial Port plug region. Particularly, in the framework of the grant F4E-2008-GRT-09-PNS-TBM, CEA/IRFM has contributed to the test blanket module system (TBS) design and robot access feasibility study in the Port Cell. Simulations of the maintenance procedure were studied and fully integrated to the design process, enabling to provide space reservation for human and robotic access. For this mean, CEA/IRFM has used a CEA LIST Virtual Reality simulation software directly integrated to the Solidworks CAD software. The feasibility to connect/dis-connect the pipes in front of the Bioshield by a set of potential standard industrial arms was demonstrated. Aiming to give more realism to maintenance scenario and CAD models, CEA IRFM has decided to build a Virtual Reality platform in the institute, integrated to the design office. With the expertise of CEA LIST, this platform aims to provide the nearest possible links between design and remote handling needs. This paper presents the outcome of the robot access study and discusses about the Virtual Reality tools that are being developed for these applications.

Numerical simulations of concentrated suspensions of monodisperse particles in a Poiseuille flow

The dynamics of concentrated suspensions of non-colloidal, monodisperse particles in plane Poiseuille flows are investigated by fully three-dimensional numerical simulations for bulk volume fractions of 0.20–0.40 of neutrally-buoyant particles. The ensemble averages of the volume fraction and particle velocity profiles are consistent with previous experiments. A statistical analysis indicates that there is an intermediate region between particle layers near the wall and a plug region in the core, in which the behaviour of ensemble-averaged suspension field can be approximated by a continuum theory. In the intermediate region, the wall-normal and spanwise velocity fluctuations, angular velocity in the vorticity direction and particle shear stress are found to be linear functions of the distance from the wall. The particle normal stresses in the intermediate region are almost uniform, consistent with the concept of normal-stress-driven particle migration. The intermediate region decreases in extent and the width of the core region increases for larger bulk volume fractions. There is a remarkable similarity between the particle–phase pressure profiles scaled by the local shear rate for different bulk volume fractions. The particle pressure profiles in the intermediate region are compared with the rheological model proposed by Morris & Boulay (1999). The effective viscosity, evaluated from the ratio of the total shear stress to the fluid-phase shear stress, shows a good agreement with empirical viscosity relations in Couette-flow suspensions. In the present study, both non-local dynamics and finite-size effects of the particles are evident in the core of the channel. These effects are more pronounced at larger volume fractions.

Entry, start up and stability effects in visco-plastically lubricated pipe flows

Interfacial instabilities of multi-layer shear flows may be eliminated by astute positioning of yield stress fluid layers that remain unyielded at the interface(s). We study the initiation, development lengths and temporal stability of such flows in the setting of a Newtonian core fluid surrounded by a Bingham lubricated fluid, within a pipe. Flow initiation is effected by starting the flow with a pipe full of stationary Bingham fluid and injecting both inner and outer fluids simultaneously. Initial instability and dispersive mixing at the front remains localised and is advected from the pipe leaving behind a stable multi-layer configuration, found for moderate Reynolds numbers (Re), for a broad range of interface radii (ri) and for different inlet diameters (Ri), whenever the base flow parameters admit a multi-layer flow with unyielded interface. The established flows have three distinct entry lengths. These relate to: (i) establishment of the first unyielded plug close to the interface (shortest); (ii) establishment of the interface radius; (iii) establishment of the velocity profile (longest). The three entry lengths increase with Re and decrease with both the Bingham number (B) and the viscosity ratio (m). Nonlinear temporal stability to axisymmetric perturbations is studied numerically, considering initial perturbations that are either localised in yielded parts of the flow or that initially break the unyielded plug regions. The aim is to understand structural aspects of the flow stability, not easily extracted from the energy stability results of Moyers-Gonzalez, Frigaard & Nouar (J. Fluid Mech., vol. 506, 2004, p. 117). The initial stages of a stable perturbed flow are characterised by a very rapid decay of the perturbation kinetic energy during which time the unyielded plug reforms (or breaks and reforms). This is followed by slower exponential decay on a viscous timescale (t ~ Re). For smaller Re and moderate initial amplitudes A, the perturbations decay to the numerical tolerance. As either Re or A is increased sufficiently, a number of interesting phenomena arise. The amount of dispersion increases, making the interfacial region increasingly diffuse and limiting the final decay. At larger Re or A, we find secondary flow structures that persist. A first example of these is when the shear stress decays below the yield stress before the velocity perturbation has decayed, leading to freezing in of the interface shape. This can lead to flows with a rigid wavy interface. Secondly, depending on the core fluid radius and thickness of the surrounding plug region, we may observe a range of dispersive structures akin to the pearls and mushrooms of d'Olce et al. (Phys. Fluids, vol. 20, 2008, art. 024104).

Plug flow formation and growth in Da Vinci fluids

A model is discussed for flow of dense granular matter—a da Vinci fluid. The local properties of the fluid are generically different from ordinary fluids in that energy is dissipated by solid friction. We discuss the equation of flow of such a fluid and show that it gives rise to formation and growth of plug regions—a phenomenon observed frequently in flow of granular matter. Simple explicit examples are presented to illustrate the evolution of plug flow regions.

Neutronic analysis of the ITER poloidal polarimeter

The nuclear heating rates of the optical mirrors of the poloidal polarimeter installed in the equatorial port plug of ITER are calculated. Since the system cannot have a sufficiently labyrinthine structure and the second mirrors are located closer to the plasma than the first mirrors due to limited space, the nuclear heating rate of the second mirrors is as high as that of the first mirrors. However, it is possible to reduce the nuclear heating rates more than 1 order if the blanket shield module provides a sufficient degree of neutron shielding. The effect of the neutron shield on the peripheral region of the upper port plug, in which the optical system of the poloidal polarimeter is installed, is also evaluated. The gamma-ray dose rate 10 6 s after shutdown of operations in the back flange region has been estimated to be ∼60 μSv/h when the neutron shield is filled in the port plug, which is below the design threshold for the ITER maintenance phase. Further, the nuclear heating rate of the Poloidal field coil near the same upper port has been evaluated to be more than 2 orders lower than the allowable value of 1 mW/cc.

ICONE19-43720 ENGINEERING SCALE TESTS OF MECHANICAL DISASSEMBLY AND SHORT STROKE SHEARING SYSTEMS FOR FBR FUEL ASSEMBLY

Japan Atomic Energy Agency (JAEA) and The Japan Atomic Power Company (JAPC) have been developing an advanced head-end process based on mechanical disassembly and short stroke shearing systems as a part of Fast Reactor Cycle Technology Development (FaCT). Fuel pins for a fast reactor are installed within a hexagonal shaped wrapper tube made of stainless steel. In order to reprocess the fast reactor fuel pins, they must be removed from the wrapper tube and transported to the shearing system without failure. In addition, the advanced aqueous reprocessing process, called "NEXT" (New Extraction System for TRU Recovery) process requires a solution of the spent fuel with relatively high concentration (500g/L). JAEA and JAPC have developed the mechanical disassembly and the short stroke shearing technology which is expected to make fragmented fuel to satisfy these requirements. This paper reports the results of engineering scale tests on the mechanical disassembly and short stroke shearing systems. These tests were carried out with simulated FBR fuel assembly and removed pins. The mechanical cutting method has been developed to avoid fuel pin failure during disassembly operation. The cutting process is divided into two modes, so called "slit-cut" for cutting the wrapper tube and "crop-cut" for the end plug region of the fuel pin bundle. In the slit-cut mode, the depth of cutting was automatically controlled based on the calculated wastage of the cutting tool and deformation of the wrapper tube which had been measured before the cutting. This procedure was confirmed to minimize the fuel pin failure which was hard to prevent in the case of laser cutting. The cutting speed was also controlled automatically by the electric current of the cutting motor to lower the load of the cutting tool. The removed fuel pins were transported to the shearing machine, whose fuel shearing magazine width was set to be narrow to realize the suitable configuration for the short stroke shearing. In the short stroke shearing test, the simulated fuel pins of a commercial reactor and the prototype reactor "MONJU" were sheared at the length of 10±5mm with enough opening at both ends.

1K1348 Effect of the plug region deletion of PomB on function of the Na^+-driven flagellar stator in Vibrio alginolyticus(Cell biology 1,The 49th Annual Meeting of the Biophysical Society of Japan)

1K1348 Effect of the plug region deletion of PomB on function of the Na^+-driven flagellar stator in Vibrio alginolyticus(Cell biology 1,The 49th Annual Meeting of the Biophysical Society of Japan)